Symposium Organizers
Mariappan Parans Paranthaman, Oak Ridge National Laboratory
Ayyakkannu Manivannan, USDOE/NETL
Yang-Kook Sun, Hanyang University
Donghai Wang, The Pennsylvania State University
Symposium Support
Aldrich Materials Science
EE4.2: Cathodes and Alternate Electrodes
Session Chairs
Tuesday PM, March 29, 2016
PCC North, 100 Level, Room 124 A
2:30 PM - *EE4.2.01
Advanced Surface Characterization and Surface-Controlled Compositional Design of Nickel-Rich Layered Oxide Cathodes for Lithium-Ion Batteries
Arumugam Manthiram 1,Wangda Li 1,Jin-yun Liao 1,Jianming Zheng 1
1 Univ of Texas-Austin Austin United States,
Show AbstractLithium-ion batteries have aided the revolution in portable electronic devices, and they are now being intensively pursued for electric vehicles and grid storage. Cost, safety, cycle life, and energy and power densities are the major factors that need to be considered for the various applications. With an aim to increase the charge-storage capacity and energy density, nickel-rich layered oxide cathodes LiNi1-x-yMnxCoyO2 with Ni content > 0.5 are emerging as potential candidates. However, realizing a charge-storage capacity > 200 mAh/g involves charging above 4.3 V. At the higher operating voltages, nickel reacts aggressively with the organic electrolyte used, and the resulting solid electrolyte interphase (SEI) layer formed leads to capacity fade and a drop in the working voltage during cycling due to impedance growth. A firm fundamental understanding of the origin of the fast capacity fade with advanced characterization methodologies and design and development of nickel-rich cathode compositions with robust surface structure are critically needed to realize their full potential in practical cells. Accordingly, this presentation will focus on the characterization of nickel-rich layered oxides with advanced surface techniques and development of less reactive surface structures.
To develop a fundamental understanding of the SEI layer formation, the nickel-rich layered oxide cathodes (e.g., LiNi0.7Mn0.15Co0.15O2) with different secondary particle sizes of 10 – 20 microns are investigated before and after cycling with X-ray photoelectron spectroscopy (XPS), time-of-flight – secondary ion mass spectroscopy (TOF-SIMS), and high-resolution transmission electron microscopy. In-depth surface characterization as a function of sputtering time reveals that the surface active mass dissolution, exacerbated by the attack of the acidic species in the electrolyte, as well as the surface phase transformation are effectively suppressed by an increase in the secondary particle size and decrease in the surface area of the cathode material, resulting in enhanced cycling stability. In addition, as the Mn content in LiNi0.8-xCo0.1Mn0.1+xO2 increases, the irreversible side reactions between the electrode surface and the electrolyte decrease, leading to significantly improved surface structural stability and cycle life. Based on the understanding gained with the in-depth surface characterization methodologies and compositional control, concentration-gradient samples with a continuously decreasing Ni content from the interior to the surface and an increasing Mn content from the interior to the surface are designed and developed employing a continuously stirred tank reactor. The concentration-gradient nickel-rich layered oxides with a high concentration of electrochemically inert Mn4+ ions on the surface and a secondary particle size of around 14 micron exhibit remarkable cycling stability both at ambient temperature and 55 oC in full cells fabricated with graphite anode.
3:00 PM - EE4.2.02
Polymorphism in KFeSO4F: Structural, Electrochemical and Magnetic Properties
Laura Lander 2,Gwenaelle Rousse 3,Artem M. Abakumov 4,Moulay-Tahar Sougrati 5,Gustaaf Van Tendeloo 4,Jean-Marie Tarascon 2
1 Chimie du Solide et Energie College de France Paris France,2 RS2E Paris France,1 Chimie du Solide et Energie College de France Paris France,2 RS2E Paris France,3 UPMC Paris 6 Paris France4 EMAT University of Atnwerp Antwerp Belgium5 ICGM, Université Montpellier Montpellier France
Show AbstractSince the discovery of the promising electrode material LiFePO4, recent research has been focusing on the development of new iron-based polyanionic materials for next generations Li- and Na-ion batteries displaying better performances while still preserving cost and sustainability benefits.1,2 On this quest, our group explored the wide family of sulfate-based compounds, where the most prominent members are monoclinic Li2Fe(SO4)2 showing a potential of 3.83 V vs Li+/Li0 and LiFeSO4F crystallizing either in a tavorite or triplite crystal structure with the latter presenting a potential of 3.9 V vs Li+/Li0 .3,4
In order to further investigate the rich crystal chemistry offered by 3d-metal-based fluorosulfates, we studied the effect of the replacement of Li by other alkali metals such as Na and K. One of the so discovered phases was KFeSO4F, which crystallizes in the orthorhombic Pna21 space group and from which K+ ions can be extracted in a complex electrochemical process.5
Knowing that sulfate-based compounds are prone to polymorphism, we recently unveiled a new low-temperature KFeSO4F polymorph.6 Using combined synchrotron and neutron powder diffraction as well as electron diffraction, it was shown that the compound adopts a complex layered-like structure that crystallizes in a large monoclinic unit cell. Impedance measurements together with the Bond Valence Energy Landscape approach show that the K+ ions, which are located between the layers, are mobile within the structure and can be electrochemically removed at an average potential of 3.7 V vs. Li+/Li0. Lastly, neutron diffraction experiments coupled with SQUID measurements reveal a long range antiferromagnetic ordering of the Fe2+ magnetic moments. These results confirm once more the richness of polymorphisms in sulfate-based materials and we hereby want to encourage the further exploration of their interesting electrochemical and physical properties.
(1) Padhi, A. K.; Nanjundaswamy, K. S.; Masquelier, C.; Goodenough, J. B. J. Electrochem. Soc. 1997, 144 (8), 2581–2586.
(2) Masquelier, C.; Croguennec, L. Chem. Rev. 2013, 113 (8), 6552–6591.
(3) Reynaud, M.; Ati, M.; Melot, B. C.; Sougrati, M. T.; Rousse, G.; Chotard, J.-N.; Tarascon, J.-M. Electrochem. Commun. 2012, 21, 77–80.
(4) Ati, M.; Melot, B. C.; Chotard, J.-N.; Rousse, G.; Reynaud, M.; Tarascon, J.-M. Electrochem. Commun. 2011, 13 (11), 1280–1283.
(5) Recham, N.; Rousse, G.; Sougrati, M. T.; Chotard, J.-N.; Frayret, C.; Sathiya, M.; Melot, B. C.; Jumas, J.-C.; Tarascon, J.-M. Chem. Mater. 2012, 24, 4363-4370.
(6) Lander, L.; Rousse, G.; Abakumov, A. M.; Sougrati, M.; van Tendeloo, G.; Tarascon, J.-M. J Mater Chem A 2015, Advanced Paper.
3:15 PM - EE4.2.03
High-Voltage High-Capacity Lithium-Nickel-Manganese Oxide Li1+xNi0.5Mn1.5O4.0 (0 < x < 1) with Spherical Particle Morphology Designed for Direct Application vs. Graphite in Lithium-Ion Batteries
Peter Axmann 1,Giulio Gabrielli 1,Marilena Mancini 1,Michael Kinyanjui 3,Ute Golla-Schindler 2,Ute Kaiser 2,Margret Wohlfahrt-Mehrens 1
1 ECM Zentrum für Sonnenenergie- und Wasserstoff-Forschung Baden-Württemberg (ZSW) Ulm Germany,2 Group of Electron Microscopy of Material Science University of Ulm Ulm Germany,3 Helmholtz Institute Ulm Germany2 Group of Electron Microscopy of Material Science University of Ulm Ulm Germany
Show AbstractKey issues in lithium ion battery development are cost reduction, increase of energy density and safety, availability of the raw materials and environmental benignity. Especially cobalt and nickel, used in most cathode active materials, are regarded critical with respect to accessibility and cost.
In our labs we developed a cobalt free low nickel content cathode material having both well pronounced high-voltage and high-capacity attributes. The material was tailored with respect to particle architecture and particle size and shape distribution in order to meet the specifications of commercially available cathode materials. The particles are of spherical morphology; they consist of densely packed nano-sized primary crystallites. The free-flowing powder shows a tap-density of 2.4 g/cm3.
The material operates on two distinct voltage plateaus at 4.7 and 2.9 V vs. Li/Li+, providing an overall capacity of > 210 mAh/g with good cycle stability between 4.9 and 2.4 V vs. Li/Li+. Higher specific capacities can be obtained by further extending the operating voltage window.
Compared to other high-capacity materials such as lithium-manganese-rich layered oxides, their spinel integrated variants and the cation disordered materials [1-3] this material does not need an activation cycle; it shows good rate capability and low voltage hysteresis.
For full-cell application no electrochemical pretreatment or structural activation has to be applied in order to achieve the full capacity; therefore, the material can be directly assembled vs. graphite as anode.
Material features will be described, results of half- and full-cell tests will be presented and the influence of the voltage operating window will be shown. The effects of particle shape and grain architecture and structural features on the electrochemical behavior will be discussed.
Acknowledgement:
The work was funded by the Federal Ministry of Education and Research as part of an Excellent Battery Initiative called the LiEcoSafe project. Its funding code is 03X4636A.
References:
[1] Thackeray, M.M.; Kang, S.-H.; Johnson, C.S.; Vaughey, J.T.; Benedek, R. and Hackney, S.A.; J. Mater. Chem., 2007, 17, 3112
[2] Park, S.-H.; Kang, S.-H., Johnson, C.S., Amine, K.; Thackeray, M.M.; Electrochemistry Communications 9 (2007) 262
[3] Yabuuchi, N.; Takeuchi, M.; Nakayama, M.; Shiiba, H.; Ogawa, M.; Nakayama, K.; Toshiaki Ohta, T.; Endo, D.; Ozaki, T.; Inamasu, T.; Sato, K.; and Komaba, S.; PNAS, 2015, 112, 7650
3:30 PM - EE4.2.04
New Insight of Voltage Fade of Lithium-Manganese-Rich Transitional Metal Oxides
Zonghai Chen 1,Yan Li 1,Guiliang Xu 1,Khalil Amine 1
1 Argonne National Laboratory Lemont United States,
Show AbstractIn the past decade, major effort has been devoted to understanding the structure and the electrochemical benefit of lithium-rich transition metal oxides for high-energy density lithium-ion batteries. However, a consensus has not been established yet on the local structure of this class of materials. It has been reported that the excess portion of lithium was homogeneously dissolved in the matrix of the transition metal layer (3b sites of space group 166 or R-3m), forming a solid solution. On the other hand, Thackeray and others believed that the excess lithium on 3b sites has a strong tendency to pair with manganese and segregate to form Li2MnO3 domains. Despite the discrepancy in these researchers’ findings on the local structure, both sides agreed that the excess lithium can be electrochemically activated at a potential above 4.5 V vs. Li+/Li to deliver more reversible specific capacity, offering great opportunity for use of these lithium-rich transition metal oxides as high-capacity cathode materials. However, the structural instability of the material after electrochemical activation causes a continuous decrease in its working potential, a phenomenon which we will call voltage fade, that hinders the commercial deployment of this class of high-capacity cathode materials. Chemical doping and surfacing coating have been attempted to suppress the voltage fade but with little success because of the lack of understanding of the local structure and the mechanism of the voltage fade. Our recent results showed that the votage fade of this class of materials was originated from the migration of Mn2+ inside the oxygen framework. The structural and electrochemical evidence to support the Mn2+ migration will be discussed in detail.
3:45 PM - EE4.2.05
Reaction Mechanism and Dynamics of Selenium as Cathode for High Energy Density Lithium-Ion Battery
Qianqian Li 1,Heguang Liu 2,Jinsong Wu 1,Vinayak Dravid 1
1 Department of Materials Science and Engineering, The NUANCE Center Northwestern University Evanston United States,2 Department of Materials Science and Engineering Northwestern Polytechnical University Xi'an China
Show AbstractSelenium, with similar chemical properties as sulfur, has recently attracted much research attention as potential electrodes for high energy density lithium-ion batteries.1, 2 Unlike sulfur cathode with poor cycling performance due to the instability of Li-S compounds formed in lithiation and delithiation, Se is promising in regards to improvement in the cycling stability. We have used in situ transmission electron microscopy (TEM) to investigate the reaction mechanism and dynamics in the lithiation and delithiation cycles. We observe that single crystalline structure of pristine selenium nanowire gradually transformed to a polycrystalline structure as lithium continue insertion without intermediate amorphous phase formed during the whole lithiation process. And Li2Se phase with a polycrystalline structure finally forms after full lithiation. Li-Se alloying reaction accompanies with dramatic volume expansion, including both elongation along axil direction and expansion in radial direction. High density of stress and strain occurs at reaction front region, and then these stresses and strains rapidly glide to unreacted region, and move out of the nanowire from the surface and edge eventually. This process efficiently drives large amount of lithium ions to move forward. For comparison, we studied also the structural evolutions in the sodiation and desodiation which may have great implications for the development of sodium-ion batteries. These observations and experiments not only can help to deeply understand the reaction mechanism and reaction process, but favor to design novel nanostructure of electrodes with excellent electrochemical performance.
This work was supported as part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DEAC02-06CH11357, and the Initiative for Sustainability and Energy at Northwestern (ISEN). This work was also supported by the NUANCE Center, and made use of the EPIC facility (NUANCE Center-Northwestern University), which has received support from the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); and the State of Illinois, through the IIN.
Reference
1. Abouimrane, A.; Dambournet, D.; Chapman, K. W.; Chupas, P. J.; Weng, W.; Amine, K. Journal of the American Chemical Society 2012, 134, (10), 4505-4508.
2. Cui, Y.; Abouimrane, A.; Lu, J.; Bolin, T.; Ren, Y.; Weng, W.; Sun, C.; Maroni, V. A.; Heald, S. M.; Amine, K. Journal of the American Chemical Society 2013, 135, (21), 8047-8056.
4:30 PM - *EE4.2.06
Engineered Fluids as Nonflammable Battery Electrolytes
Ganesan Nagasubramanian 1,Christopher Orendorff 1
1 Sandia National Laboratories Albuquerque United States,
Show AbstractAbstract
Although Li-ion battery chemistries were introduced into the commercial market nearly two decades ago, there is only limited adoption as power sources in the EV market. Limitations to the adoption of Li-ion technologies include safety concerns related to thermal runaway, self-ignition, and fire. . Additionally, the consequences scale with energy. The Achilles’ heel of thermal instability mainly comes from the propensity of solvent combustion resulting from a cell vent or rupture. Thus mitigating or eliminating the electrolyte solvent combustion properties is imperative for wide-spread Li-ion battery adoption in the EV and energy storage applications.
Over the years several different solvents or solvent blends have been studied with no or small improvement in thermal stability or ignition characteristics. Fire retardant materials have been studied as additives at low concentration to battery electrolytes with very limited success due to the shortcomings of the additives which will be described at the meeting.
However, our approach revolves around utilizing no flash point co-solvents at >30% concentration in the battery solvent. For this study, we evaluated the performance and abuse tolerance of two “engineered fluid” hydrofluoro ether (HFE) candidates as co-solvents in battery electrolytes. Characterization of the HFE-based electrolytes is performed in LiNixMnyCozO2/graphite 18650 cells. Results show that the solvents blends do not significantly impact the important electrolyte properties and battery performance but do provide nonflammable characteristics under cell failure test conditions.
In this presentation, we will describe electrochemical, thermal studies etc. in 18650 cells and highlight the strengths and weaknesses of these co-solvents.
Acknowledgment
Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000
5:00 PM - EE4.2.07
Exploration of New Borate Based Cathode Materials for Lithium- and Sodium-Ion Batteries
Florian Strauss 3,Gwenaelle Rousse 4,Mohamed Ben Hassine 5,Mingxue Tang 4,Herve Vezin 4,Daniel Dalla Corte 4,Robert Dominko 3,Jean-Marie Tarascon 4
1 College de France Paris France,2 National Institute of Chemistry Ljubljana Slovenia,3 ALISTORE-ERI Amiens France,1 College de France Paris France,3 ALISTORE-ERI Amiens France,4 Reseau sur le RS2E - Stockage Electrochimique de l’Energie Aminens France5 Ecole Centrale Paris Paris France6 Universite Orleans Orleans France,4 Reseau sur le RS2E - Stockage Electrochimique de l’Energie Aminens France7 Universite Lille Lille France,4 Reseau sur le RS2E - Stockage Electrochimique de l’Energie Aminens France1 College de France Paris France,4 Reseau sur le RS2E - Stockage Electrochimique de l’Energie Aminens France2 National Institute of Chemistry Ljubljana Slovenia,3 ALISTORE-ERI Amiens France
Show AbstractIn the search for new polyanionic cathode materials for Li- and Na-ion batteries, borate based materials could lead to increased capacities since the borate anion BO33- presents the lightest group among all polyanions. However, so far only materials consisting of an ortho borate BO33- polyanionic framework have been considered as potential positive electrode materials.1,2 Because the borate BO33- group has a weak inductive effect on the transition metal, the redox voltage is rather low compared to other common polyanionic cathode materials like LiFePO4 or LiFeSO4F.2
One strategy to increase the redox potential versus lithium or even sodium for a polyanionic material, containing the same transition metal, has been shown for LiFePO4 and its counterpart Li2FeP2O7. Replacing the ortho-phosphate PO43- by a di- or pyro- phosphate group P2O74- which is more electron withdrawing, leading to an elevated redox potential.3
So to combine the advantage of the light weight of borate groups and simultaneously increase the redox potential of the transition metal, our approach is to apply this strategy of using condensed polyanionic groups, for instance moving from borate BO33- to pyroborate B2O54- or pentaborate B5O105-.
In this context we prepared a lithium copper pyrobrate Li6CuB4O10 using ceramic synthesis and investigated its electrochemical and structural properties by a variety of in situ and ex situ XRD as well as galvanostatic electrochemical methods combined with TEM and EPR spectroscopy. This material shows a 4.0 V redox potential versus lithium and an a.c. conductivity around 10-2.5 S/cm at temperatures higher than 300°C, determined by temperature controlled impedance measurements.
To further probe the electrochemical activity of new polyborate based materials, we successfully prepared a new group of sodium transition metal pentaborates Na3MB5O10 (M = Mn, Fe, Co) by a ceramic process. We solved their crystal structure using synchrotron diffraction and characterized these materials in terms of magnetism, optical and electronic properties since their electrochemical activity versus sodium was rather small.
Finally we studied the reversible conversion reaction, of a bismuth oxyborate Bi4B2O9 versus Li/ Na potential application as a high energy density cathode material. This material show a moderate capacity even at elevated C-rates and a good capacity retention rates (150 mAh/g at 1C over 20 cycles) with a small polarization (0.4 V). We studied the conversion mechanism and influence of different parameters like electrolyte, carbon content and milling time on the electrochemical behavior.
[1] V. Legagneur, Y. An, A. Mosbah, R. Portal, A. Le Gal La Salle, A. Verbaere, D. Guyomard, Y. Piffard, Solid State Ionics 139 (2001) 37-46.
[2] A. Yamada, N. Iwane, Y. Harada, S. Nishimura. Y. Koyama, I. Tanaka, Adv. Mater. 22 (2010) 3583-3587.
[3] S. Nishimura, M. Nakamura, R. Natsui, A. Yamada, J. Am. Chem. Soc. 132 (2010) 13596-13597.
5:15 PM - EE4.2.08
A Study of the Advanced Layered NCM Cathode Material for High Energy Lithium-Ion Batteries
Zhenlian Chen 1,Xianhui Zhang 1,Zhifeng Zhang 1,Heng Ren 1,Jun Li 1
1 Ningbo Institute of Industrial Technology, Chinese Academy of Sciences Ningbo China,
Show AbstractLayered Li(NiCoMn)1/3O2 (NCM) has been a major cathode material for current 4.2V lithium-ion battery technology. Its potential as a high energy cathode material depends crucially on its electrochemical stability in the high voltage window. Here, we reported an advanced NCM material, which shows extraordinary electrochemical performances in both regular and high voltage windows. Typically, this NCM material can release discharge capacity above 200mAh/g at current density180mA/g (1C) between 2.8-4.8V window and above 140 mAh/g at 10C (1800mA/g) between 2.5-4.3V window. More interestingly, it presents high stability in high rate cycling; no crack has been noticed after 100 electrochemical cycles at high rates (up to 100C). To understand what controls the electrochemical properties of this material, we performed ex situ and in situ Synchrotron X-ray diffractions, combined with Neutron diffraction, high-resolution transmission electron microscopy to characterize the crystal structure evolution in electrochemical cycles. From cyclic voltammetry characterization, oxidation/reduction peaks of cobalt cation, which rarely reported in literature, are found stably for cycles with different scan rates. The oxidation potentials (Ni2+/Ni4+ as well as Co3+/Co4+) at the second cycle shift to a lower potential with respect to the first one for most scan rates, except for a mediate rate of 0.5mV/S. Extended first-principles calculations are also performed to provide deep insights on destabilizing factors such as Li/Ni mixing and transition metal ions trapped in tetrahedral sites.
5:30 PM - EE4.2.09
Identifying the Sequence of Lithiation of LiFePO4 Particles in a Porous Electrodes
Yiyang Li 1,Sophie Meyer 1,Jongwoo Lim 1,David Shapiro 2,Tolek Tyliszczak 2,A. L. David Kilcoyne 2,William C. Chueh 1
1 Stanford Univ Stanford United States,2 Berkeley National Laboratory Berkeley United States
Show AbstractThe sequence in which particles in a porous battery electrode charge or discharge is an important indicator of loss mechanisms in a battery electrode, and understanding which certain particles lithiate before others provide guidance on engineering batteries with higher power density. For the phase-separating electrode LiFePO4, the dependence of the sequence of lithiation on particle size is a controversial point. In this work, we use synchrotron-based scanning X-ray imaging on ~ 800 particles to determine which particles lithiate first in an electrode. We show that the smaller particles preferentially lithiate when the carbon black forms a fully percolated network; when the carbon black connectivity is heterogeneous, the particles adjacent to the carbon black preferentially lithiate, and there is negligible size dependence. Thus, we propose that local variations in the electronic connectivity between LiFePO4 and carbon black particles mask the particle size dependence of lithiation, and that the most resistive process in a LiFePO4 electrode is the electronic conduction between the particles' surface and the nearest branch of the percolated carbon network.
5:45 PM - EE4.2.10
In Situ Synthesis of High-Energy Cathodes for Li-Ion Battery
Jianming Bai 1,Liping Wang 1,Jianqing Zhao 1,Wei Zhang 1,Dawei Wang 1,Feng Wang 1
1 Brookhaven National Laboratory Upton United States,
Show AbstractDespite considerable interest in developing high-energy cathodes for Li-ion batteries, preparing new battery materials of desired phases and properties has proven difficult due to the complexity of the reactions involved in chemical synthesis. In-situ, real time probing of structural and chemical evolution under real conditions provides direct information of the synthesis reactions, elucidating intermediates, and detailing how temperature, time, and precursor concentration affect the kinetic reaction pathway. Such kind of in-situ studies (of a particular reaction) may also be coupled with combinatorial screening of a large number of synthesis parameters in the search for new cathode materials, eventually enabling strategies to synthetic control of the phases and material properties. Herein, we report on in-situ X-ray diffraction studies of synthesis reaction in preparing high-energy layered oxide cathodes (i.e. Li-Mn-Nn-Co-O) and polyanioic type cathodes (Li-M-PO4; M=Fe, Mn, V), demonstrating how insights gained from these studies can be applied to gain precise control of the phase, stoichiometry and morphology of the materials [1, 2]. This research was supported by DOE-EERE under the Advanced Battery Materials Research (BMR) program, under Contract No. DE-SC0012704.
[1] J. Bai, J. Hong, H. Chen, J. Graetz and F. Wang, J. Phys. Chem. C.119, 2266 (2015).
[2] L. Wang, J. Bai, P. Gao, X. Wang, and F. Wang, Chem. Mater., 27, 5712 (2015)
EE4.3: Poster Session I
Session Chairs
Wednesday AM, March 30, 2016
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - EE4.3.01
Manganese Sulfide ss Anode Material For Lithium-Ion Batteries
Yong Hao 1,Chunhui Chen 1,Bo Zou 2,Chunlei Wang 1,Richa Agrawal 1
1 Florida International University Miami United States,2 Jilin University Changchun China
Show AbstractAmong the various candidates of electrode materials, manganese sulfide (MnS) has attracted much attention especially due to its outstanding electrical properties and nanocrystalline structures. Generally, MnS exhibits polymorphism and the most common phase structures are: the stable rock salt (α-MnS), the metastable zinc blende (β-MnS) and wurtzite (γ-MnS) structures. Both tetrahedrally coordinated β-MnS and γ-MnS forms can only exist in the low-temperature range (below 100°C). In this work, we have successfully synthesized MnS with three different structural phases (α-, β- and γ-phase MnS). In order to examine the morphology and crystallinity, TEM and XRD are respectively carried out for examining the obtained materials. Furthermore, to investigate the electrochemical performance of MnS as electrode material, cyclic voltammetry (CV), galvanostatic charge-discharge, cycling performance and electrochemical impedance spectroscopy (EIS) experiments have been carried out in half cells. It has been observed the capacity gradually increased with the cycles reaching 600. XRD and TEM have been applied on the samples after cycling. The potential mechanism of capacity increasing and details of the electrochemical performance base on the conversion mechanism will be discussed during the meeting.
9:00 PM - EE4.3.02
Enhanced High Rate Capacity Nickel Oxide via Nano-Confinement
Chunhui Chen 1,Chunlei Wang 1,Richa Agrawal 1
1 Florida International University Miami United States,
Show AbstractLithium ion batteries (LIBs) with substantially higher power densities, faster charge/discharge capability and longer cycle lifetime have attracted considerable attentions. NiO has a high theoretical capacity of 718 mAh g-1 when it is used as anode material for LIBs, thus has been widely researched. However, it shows poor cycling performance due to the low electrical conductivity and large volume change during charge/discharge. The carbon nanotubes (CNTs) that have the well-defined nanochannels owns unique electronic properties which is expected be beneficial for the lithium ions storage for NiO. Furthermore, the CNTs can also provide an intriguing confinement, in which nanoparticles are likely to exist in a more reduced state. In the present work, the confinement of NiO inside CNTs and its effect on lithium ions storage property have been studied. The CNTs were first treated with acid to open the tips, then the NiO precursor were introduced into CNT channels through capillary force. The electrode were prepared using electrostatic spray deposition (ESD). Various NiO loading (0%, 10% and 50%, wt%) were exam and excellent electrochemical performance was observed. 10% NiO loading in cut-CNTs (CCNT) shows a reversible capacity of 650 mAh g-1 at 0.5 A g-1 rate and when the rate increased to 20 A g-1, a capacity of 78 mAh g-1 is still achievable. For higher NiO loading of 50%, the reversible capacity increased to 917 and 250 mAh g-1 under the rate of 0.5 and 20 A g-1, respectively. The underlying mechanisms of enhanced capacity were studied and will be reported in the meeting.
9:00 PM - EE4.3.03
Reduction of PVdF-HFP Penetration into PE Separator Using Low Molecular Weight Ionic Fillers for Lithium-Ion Batteries
Roya Naderi 1,Ashim Gurung 1,Qiquan Qiao 1
1 South Dakota State University Brookings United States,
Show AbstractHybrid polymer electrolyte (HPE) films, consisting of poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) as the membrane, mixture of positively charged TiO2 and nano-powder SiO2 or hydrolyzed tetraethyl orthosilicate (TEOS) as ionic fillers, and LiClO4/LiPF6 as lithium salts. Gel electrolyte films were characterized by X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). Likely, the pore distribution was measured by scanning electron microscope (SEM). Electrochemical cycling of batteries were also performed for 50 cycles. In the mixture of positively charged TiO2 and nano-powder SiO2 or hydrolyzed TEOS, TiO2+ nano-filler enhanced the ionic dissociation rate of Li salts, SiO2 or hydrolyzed TEOS particles provided a more amorphous structure of inorganic compounds due to maintaining anatase phase of TiO2 versus the more crystalline Rutile phase. However, ceramic fillers play an important role in temperature stability of the film and enhanced interfacial properties as well. TiO2 can also absorb UV light to produce crosslinking agents for a better adhesion to PE separator and achieve a more liquid electrolyte uptake. The PE separator was O2 plasma treated to improve the hydrophilicity properties. Later the O2 plasma treated separator was dipped initially in the mixture of “PVDF-HFP:LiClO4/LiPF6:TiO2+/SiO2:Organic solvents” with a ratio of “1.3:1:0.13:13” and then coated with the same mixture components but with a different ratio of “1.6:1:0.16:16” using solution casting technique. Silica nano-particles were provided using commercial SiO2 nano-powders and extracted SiO2 from hydrolyzed TEOS and their compatibility comparisons were reported separately. Half-cell batteries were then assembled and electrochemical measurements such as charging/discharging cycles and voltage versus capacity plots were conducted. The cells whose separators were pretreated demonstrated a significant enhancement of capacity from 1 mAh/g in non-treated separator to 34 mAh/g at the first cycle. The SEM images exhibited more pores in pretreated separator due to less penetration of high molecular weight PVDF-HFP components.
9:00 PM - EE4.3.04
Direct Growth of MnO Nanoplates on Stainless Steel and Their Electrochemical Properties
Corey Arnold 1,Milana Jones 2,Levon LeBan 1,LaMartine Meda 1
1 Chemistry Xavier University of Louisiana New Orleans United States,2 Materials Science and Engineering University of Texas at Dallas Richardson United States
Show AbstractTransition metal oxides are a class of anode materials for lithium ion batteries. They possess higher theoretical capacities than that of graphite and store charges through conversion reactions with lithium, within which electrochemical reduction leads to the transfer of at least two Li ions. Carbon coating is required for transition metal oxides in battery application. However, utilization of low cost and abundant metals such as Mn provides a variety of scalable electrode alternatives. Direct growth of nanomaterials on current collectors has several benefits such as sufficient empty space to accommodate the volume change, electrical contacts to the current collector, efficient charge transport, and no need of polymer binder and conductive carbon. We have deposited MnO nanoparticles directly on stainless steel by chemical vapor deposition (CVD) method using a volatile precursor material, Mn(acac)2 (acac=acetylacetonate). As prepared, the material was characterized by powder x-ray diffraction and scanning electron microscope techniques. It possesses cubic MnO structure with a film thickness of 1 μm. Electrochemical charge-discharge experiments were carried out versus Li metal. High experimental capacity of ~975 mAh/g was achieved during the first cycle with high cyclability and an increase in capacity for subsequent cycles.
9:00 PM - EE4.3.05
Electrochemical Behavior of Nanostructured Nickel Oxides as Pseudocapacitor and Battery
Corey Arnold 1,Joshua Adkins 1,LaMartine Meda 1
1 Chemistry Xavier University of Louisiana New Orleans United States,
Show AbstractNanosized NiO with various morphology was successfully deposited directly onto stainless steel 304 substrates using a low pressure chemical vapor deposition process. XRD and EDS patterns confirmed the presence of NiO. SEM images offered a detailed look at the morphologyof the as-deposited nanoplates and nanorod-like NiO materials before and after discharges. The annealed NiO was analyzed into a homemade Swagelok cell and ran through Galvanostatic charge-discharge in the voltage range of 0.1 – 4.0 V at a constant current of 0.1 mA vs Li/Li+ in 1:1:1: EC, DMC, and DC, respectively.Crystalline plate/rod-like NiO behaves in a manner reflective of both a capacitor and a battery, and thus is defined as a pseudocapacitor. The annealed NiO nanorods show a first-cycle capacity of about 782 mAh/g – not far from NiO’s theoretical capacity of 712 mAh/g. The capacity then drops to about 620 mAh/g during the second cycle, and continues to decrease to about 310 mAh/g by the tenth cycle. These results are surely indicative of a capacitor. However, the material’s columbic efficiency (charge capacity/discharge capacity) stabilizes to about 85-87% after the first few cycles. This combination of battery-like columbic efficiency and capacitor-like capacity retention classifies the material as a pseudocapacitor.
9:00 PM - EE4.3.06
Cyclic Voltammetry Study of Ruthenium Oxide Nanostructured Electrode
Corey Arnold 1,Lacey Douglas 1,LaMartine Meda 1
1 Chemistry Xavier University of Louisiana New Orleans United States,
Show AbstractMetal oxides have more available lithium ions storage capability, so they are a more ideal anode to use in lithium ion batteries compared to the state-of-the-art graphite anode materials. To understand the interactions of lithium with metal oxides nanomaterials, ruthenium oxide (RuO2) have been used as a model to elucidate the mechanistic reactions. RuO2 (806 mAh g-1) has approximately twice the capacity of graphite (372 mAh g-1), thus understanding the reactions of lithium with RuO2 could lead to an increase in battery capacity. In this work, we studied the reactions of lithium ions with RuO2 using cyclic voltammetry. RuO2 nanomaterials were synthesized by low pressure chemical vapor deposition directly on stainless steel substrates. The crystal structure and the morphology were analyzed by X-ray diffraction and field emission scanning electron microscopy, respectively. The cyclic voltammetry studies were conducted to determine the origin of the excess capacity usually observes in metal oxides nanomaterials when they undergo conversion reactions. In this study, we concluded that the excess capacity originated from the depletion of the solid electrolyte interphase (SEI) and or the polymeric materials which formed during the reaction. We notice that the SEI formed only after completely cycling the cell from 0.1 to 4 volts versus Li/Li+ in 1M LiPF6 in 1:1:1 of EC, DEC, and DMC. The SEI disappeared after the first cycle with the concomitant formation of an oxidation peak at 1.5 V. When the cut off voltage was limited to 1 V no additional capacity was observed. The mechanism responsible for the excess capacity below 1 V will be discussed.
9:00 PM - EE4.3.07
Holey Graphene for Energy Storage: Implications of Chemical Treatment of Graphene Oxide to Introduce Defects
Swagotom Sarker 1
1 New Mexico State Univ Las Cruces United States,
Show AbstractThis work highlights the implications of chemical treatment of graphene oxide nanosheet to introduce defects by different oxidizers using the reflux-condensation process. Defect enhances the specific surface area and improves the ion diffusion in the graphene nanostructure. However, degree of defect in graphene oxide layers depends on the oxidizers and it is yet to be fully understood. Herein, we report the nature and the applications of holey graphene by performing morphological and electrochemical characterizations. Graphene oxide and reduced graphene oxide nanosheets are characterized using XRD, FTIR, SEM, and TEM. While TEM analyses confirm the formation of holes as a result of chemical treatment and FTIR analyses indicate that the holey graphene nanosheets retain the functional groups, XRD patterns highlight a significant shift of the (002) peak in contrast to the plain graphene oxide nanosheet. Moreover, electrochemical performances are demonstrated for lithium-ion batteries to understand the ion transport in the holey structures.
9:00 PM - EE4.3.08
Spontaneous Evolution of Nanostructures in Dealloying of Li-Sn Anode Reservoir
Ke Geng 1,Karl Sieradzki 1
1 Arizona State University Tempe United States,
Show AbstractDealloying is an important corrosion mechanism and a technologically relevant process used to fabricate nanoporous metals for a variety of applications. In metallic alloy systems displaying high solid-state mobility at ambient temperature it is relatively unexplored despite its significance in energy storage systems such as lithium-ion batteries. Current research is targeting materials for anode reservoirs such as Si and Sn that have a higher capacity to store Li than the carbon-based materials in use today. We report on dealloying of Li from Li-Sn alloys and show that depending on alloy composition, Sn particle size and dealloying rate bi-continuous nanoporous structures can evolve. Electrochemical current-voltage behavior is used to elucidate the role of solid-state mass transport, which serves to compositionally homogenize evolving nanostructures. These bi-continuous nanostructures are architecturally well suited to serve as anode reservoirs as the free volume and solid ligament length-scale in these structures can easily accommodate the large volume changes associated with lithiation, thus mitigating cracking and fracture issues in these high energy density systems.
9:00 PM - EE4.3.09
Structures and Performances of Vanadium Substituted Lithium Iron Silicates
Ying Zhang 2,Xuan Cheng 2,Xuexia Wei 1,Jiaqi Huang 1
1 Xiamen Univ Xiamen China,2 Fujian Key Laboratory of Advanced Materials Xiamen China,1 Xiamen Univ Xiamen China
Show AbstractBeing capable of obtaining higher capacity by exchanging more than one lithium ion, lithium iron silicate (Li2FeSiO4) is a promising cathode material for lithium ion batteries. Metal substitution is an effective way to reduce the deintercalation voltage and to minimize the deformation resulted during the delithiation of second lithium ion. In this work, a series of orthogonal experiments were carried out to study the effects of sintering temperature, catalyst, sol-gel time and sol temperature on the structures and performances of Li2FeSiO4 and vanadium substituted lithium iron silicates (Li2Fe1-xVxSiO4). Accordingly, the Li2Fe1-xVxSiO4 cathode materials were prepared with x=0~0.5 at the optimized conditions. The structures, morphologies, chemical states and electrochemical properties of the Li2Fe1-xVxSiO4 were systematically investigated. Possible vanadium substitution for iron in Li2Fe1-xVxSiO4 is characterized, and its relation to structure and performance of Li2Fe1-xVxSiO4 is discussed.
9:00 PM - EE4.3.10
Multifunctional Binder Containing PEDOT:PSS for Lithium-Ion Batteries
Kiung Jeon 1,Jaebeom Jeon 1,Yoon Hyung Hur 1,Jung-Keun Yoo 1,Yeon Sik Jung 1
1 KAIST Daejeon Korea (the Republic of),
Show AbstractDespite the significantly higher capacity of silicon (Si) anode compared to graphite, the extreme volume change of Si during charge and discharge cycles hinders commercialization of Si anodes. To solve that issue, many researchers have studied functional binders acting as more than two functional parts, especially conductive and binding parts. Here, we suggest a new copolymer binder, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)-g-poly(acrylamide) (PEDOT:PSS-g-PAAm) with electronic conductivity as well as excellent mechanical binding capability. Although there have been many previous studies about the click chemistry based on PEDOT-N3, synthesis of PEDOT-N3:PSS and its derivatives have not been reported yet. It is due to the low conversion of 3,4-ethylenedioxythiophene-N3 (EDOT-N3), resulting from its considerably less reactivity compared to that of pristine EDOT monomers. We overcame the challenge using hydrochloride (HCl) to improve the oxidative potential of the oxidant and could obtain PEDOT-N3:PSS with a higher electronic conductivity and stability comparable to those of pristine PEDOT:PSS. We confirmed the results using Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). The grafted copolymer demonstrates a high electric conductivity (~2 S/cm) and chemical stability. Si anode half cells prepared with the multifunctional binder showed a capacity of >1,500mAh/g with excellent retention over 50 cycles.
9:00 PM - EE4.3.11
Functionalized Carbonaceous Materials as Cathode for Lithium-Ion Batteries
Hai Zhong 1,Fei Ding 1
1 Tianjin institute of power source Tianjin China,
Show AbstractOne approach to resolving the high power density of chemical power source challenge is to adopt fast surface electrode reactions in electrodes while maintaining high energy density. Such as use advanced carbonaceous materials as cathodes for lithium ion batteries, which presence of oxygen functional groups on the surface of carbon and can be acted as radical centers to store Li ions at acceptably high potential.[1],[2]
In order to increase the energy storage/release rate, we integrated carbonaceous material into FGp nano-sheet to decrease the graphene nano-sheet stacked. The composite electrode displays the long cyclic performance of FGp/AC composite electrode, it is still delivered 124.5 mAhg-1 after 4000 cycles, and approximately 92% of the maximum capacity was maintained, suggest a perfect stability cycle performance was obtained by combination with graphene and active carbon. These data have clearly demonstrated that the composite electrode combines the advantage of graphene and active carbon, and a perfect stability cycle performance and excellent rate performance were obtained.
The composite electrode exhibited an energy density of 426 Whkg-1 at 0.5 C (1 C=200 mA g-1). The power density of composite electrode is 1.6 kW kg-1 at 3 C with an energy density of 400 Wh kg-1. The power density increases to 15.2 kW kg-1 at 30 C with an energy density of 227 Wh kg-1. This power density is much higher than that of conventional lithium-ion batteries.
In conclusion, the carbonaceous material composite was prepared through ultra-sonic dispersed, which display a perfect electrochemical energy storage performance. The composite showed a capacity around 130 mAh g-1 at 5C and after 4000 cycles still have 92% of the maximum capacity was maintained, it is show a long stability cycle performance. Additionally, the composite exhibited an excellent rate capability, it is still give 15.2 kW kg-1 power density with 227 Wh kg-1 energy density even at 30 C.
Reference
[1] B. Z. Jang, C. G. Liu, D. Neff, Z. N. Yu, M. C. Wang, W. Xiong, A. Zhamu. Nano Lett. 2011, 11, 3785–3791.
[2] S. W. Lee, B. M. Gallant, Y. Lee, N. Yoshida, D. Y. Kim, Y. Yamada, S. Noda, A. Yamada, Y. S. Horn, Energy Environ. Sci. 2012, 5, 5437−5444.
9:00 PM - EE4.3.12
Facile and Green Synthesis of Hierarchically Porous Carbon Supported Well Defined Oxide Nanoparticles for Energy Storage
Xingmao Jiang 1,Jilong Qin 1
1 Changzhou University Changzhou China,
Show AbstractMonolithic hierarchical nano porous carbon materials with high loading of well distributed oxide nanoparticles are desirable energy storage materials. Conventional fabrication methods are pollutive, multiple-step and time consuming. Furthermore, there lacks good control of the crystallinity, composition, size and size monodispersity, and distribution of the nanoparticles in the porous carbon.
Herein, a novel preparation method is reported, starting from an anhydrous precursor composed of a mixture of urea, sugar and salts, which is melt at a low temperature. Monodisperse metal oxide nanoparticles with desired size, phase, and composition are generated and well distributed in situ in the carbon through slow sugar dehydration, controlled hydrolysis of the salt molecules, hydrogen bonding, and complexation of cations by urea molecules. The self-assembly is investigated thoroughly with the precursor composition and generation conditions. Various techniques including XRD, HRTEM, nitrogen adsorption/desorption, XPS are used for characterizations of the nanostructured materials. Nano porous carbon encapsulated with cobalt, molybdenum, or manganese oxide nanoparticles demonstrated superior electrochemical performance as potential supercapacitor.
Also nano porous carbon containing bi-metal oxides such as LiCoO2, LiMnO4 are prepared successfully and investigated as promising Li-ion battery cathode materials on the electrochemical performances.
9:00 PM - EE4.3.13
Production and Characterization of Layered Cathode Materials for Lithium-Ion Batteries
Berke Piskin 1,Mehmet Kadri Aydinol 1,Aysegul Afal Genis 1
1 Metallurgical and Materials Engineering Middle East Technical University Ankara Turkey,
Show AbstractRechargeable lithium ion batteries are key components especially used in mobile applications as a power source. LiCoO2 has been adopted as the cathode material in commercial Li-ion batteries. However, capacity of cathode is limited to perform 50% of its theoretical capacity (140 mAh/g). In this regard, novel layered Li(Ni1/3Mn1/3Co1/3)O2 cathode materials have been investigated as an alternative cathodes searching for higher capacity, cycle life, rate capability and safety. Li(Ni1/3Mn1/3Co1/3)O2 cathodes exhibit higher capacity that of close to 200 mAh/g with enhanced safety. This high capacity can be associated with the improved chemical stability. However, the rate capability is the most important deficiency which should be improved for new layered Li(Ni1/3Mn1/3Co1/3)O2 cathode materials. Moreover, the electrochemical performance of cathode is strongly affected by powder properties such as morphology, surface area and composition. Therefore, in this study spray pyrolysis was used to obtain spherical fine-sized morphology followed by heat treatment to obtain better electrochemical activity. The precursor powders were prepared using aqueous solution via spray pyrolysis. Li(NixMnyCo1-x-y)O2 cathode materials were produced by using solutions of lithium nitrate (LiNO3), nickel (II) nitrate hexahydrate (N2NiO6.6H2O), manganese (II) nitrate tetrahydrate (Mn(NO3).4H2O and cobalt (II) nitrate hexahydtare (Co(NO3)2.6H2O) with the mole ratio of related compositions. The total concentration of the solution is 0.5 M with additives of citric acid and ethylene glycol. Synthesized samples werethen heat treated at 850°C. X-Ray Diffraction (XRD) pattern of obtained layered Li(Ni1/3Mn1/3Co1/3)O2 cathode material showed good [006]/[102] and [108]/[110] doublets indicating layered structure and good hexagonal ordering. Precursor concentration, droplet size, gas flow rate and temperature were optimized to obtain particles with spherical fine-sized and narrow size distribution. Li(Ni1/3Mn1/3Co1/3)O2 ratio and different nickel manganese cobalt oxide structures, Li(Ni0.2Mn0.2Co0.6)O2 (226), Li(Ni0.6Mn0.2Co0.2)O2 (622) and Li(Ni0.2Mn0.6Co0.2)O2 (262) were produced. The morphology of produced cathode materials were observed by scanning electron microscopy (SEM) and average particle size was between 0.4 and 0.6 μm. For cathode preparation, powders were mixed with polyvinylidene difluoride (PVDF) and C black with ratio as 86:7:7. PVDF was used as a solution after dissolved in N-methyl pyrrolidinone (NMP). The electrolyte is 1 M LiPF6 in 50:50 EC/DEC solution. The electrochemical cells were cycled at 0.1C and 0.3C rate (1C=170 mAh/g). Fast charging and discharging behaviours were not sufficient. However, capacity retention were %85 and %88 for 111 and 262 at 2.75-4.25 V, respectively. The electrochemical properties need to be improved, therefore doping elements W, Cr and Sn were used to improve cycling performance at high voltage.
9:00 PM - EE4.3.14
Novel Synthesis of Holey Reduced Graphene (HRGO) Using Ag Nanoparticles by Microwave Irradiation Method for Anode in Lithium-Ion Batteries
Edreese Alsharaeh 1,Yazeed Aldawsari 1,Faheem Ahmed 1,Mohammed Aldosari 2
1 Alfaisal University Riyadh Saudi Arabia,2 National Nanotechnology Research Center (NNRC) King Abdulaziz City for Science amp; Technology Riyadh Saudi Arabia
Show AbstractIn this work, a three-dimensional holey graphene framework with a hierarchical porous structure prepared by a straightforward and highly scalable method was presented. Holey graphene (HRGO) were synthesized by the deposition of silver (Ag) nanoparticles onto the reduced graphene oxide (RGO) sheets by microwave irradiation followed by nitric acid treatment to form a porous structure. The holey graphene were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), ultra violet-visible spectroscopy (UV-Vis), Thermogravimetric analysis (TGA), and Raman spectroscopy. These holey graphene anodes exhibit high rate capability with excellent cycling stability as an anode material for lithium-ion cells. The results have shown an excellent electrochemical response in terms of charge/discharge capacity (423 mAh/g at 100 mA). Cyclic performance was also exceptional as a high reversible capacity (400 mAh/g at 100 mA) was retained for 100 charge/discharge cycles. This fascinating electrochemical performance can be ascribed to their specific porous structure, providing numerous active sites for Li+ insertion, reduced effective diffusion distance for the Li+ ions, high electrical conductivity, low charge-transfer resistance across the electrolyte–electrode interface, and improved structural stability against the local volume change during Li+ insertion–extraction. Such electrodes are envisioned to be mass scalable with relatively simple and low-cost fabrication procedures, thereby providing a clear pathway toward commercialization.
9:00 PM - EE4.3.15
Novel Synthesis of Defect Li4Ti5O12 Anode with Enhanced High-Rate Capability via Ethanol Thermal Reduction
Ralph Nicolai Nasara 1,Shih Lin 1,Ping-chun Tsai 1,Kuan-zong Fung 1
1 Department of Materials Science and Engineering National Cheng Kung University Tainan Taiwan,
Show AbstractLithium titanate defect spinel (Li4Ti5O12) is one of the most promising anode materials for lithium ion batteries (LIBs) because of its negligible volume change and stable operating voltage during charging/discharging. However, the intrinsic insulating property of Li4Ti5O12 hinders its high power applications. Compositing and nanonization are two well-understood approaches to overcome this drawback. The former enhances the external electrical conductivity of Li4Ti5O12, while the latter shortens the length of diffusion during charging/discharging. Nevertheless, the effects of presence of defects, e.g. vacancies, in electrode materials are not as straightforward as compared to the former approaches. Moreover, it is technically difficulty to control the concentration and distribution of intentionally introduced vacancies, namely to engineer the defects. In this work, Li4Ti5O12 defect spinel anode were synthesized via a novel ethanol thermal reduction. The ethanol thermal reduction was facilitated by the reaction under autogenic pressure at elevated temperature (RAPET) technique. Unlike the conventional white Li4Ti5O12 powders, blue Li4Ti5O12 powder were synthesized. The microstructures and electrochemical properties, i.e., cycle performance and high-rate capability of defect spinel Li4Ti5O12 spinel were examined. In addition, ab initio calculations based on density function theory (DFT) were performed to clarify the enhanced electrochemical properties of the Li4Ti5O12 defect spinel. The formation mechanism of the Li4Ti5O12 defect spinel as well as the origin of superior electrochemical properties is elaborated in this paper.
9:00 PM - EE4.3.16
Bestow Metal Foams with Nanostructured Surface via a Convenient Electrochemical Method for Improved Device Performance
Yawen Zhan 1,Yang Yang Li 1
1 City University of Hong Kong Hong Kong Hong Kong,
Show AbstractFeaturing high conductivities and attractive mechanical properties, metal foams are intensively studied as 3-D bulk mass-support for various applications. However, the relatively low surface area of conventional metal foams largely limits their performance (e.g., in charge storage devices). Here, taking Cu foams as an example, we present a convenient electrochemical method for addressing this problem. High surface area Cu foams are fabricated in a one-pot one-step manner by repetitive electrodeposition and dealloy treatments. The thus obtained Cu foams enable greatly improved performance for different applications, e.g., as Surface Enhanced Raman Spectroscopy (SERS) substrates and 3-D bulk supercapacitor electrodes.
9:00 PM - EE4.3.17
Initiated Chemical Vapor Deposition (iCVD) of Highly Cross-Linked and Electrolyte-Wettable Polymer Films for Advanced Lithium-Ion Battery Separators
Youngmin Yoo 1,Byung Gon Kim 2,Kwanyong Pak 1,Sung Jae Han 3,Heon-Sik Song 3,Jang Wook Choi 2,Sung Gap Im 1
1 Department of Chemical and Biomolecular Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon Korea (the Republic of),2 Graduate School of Energy, Environment, Water, and Sustainability (EEWS) Korea Advanced Institute of Science and Technology (KAIST) Daejeon Korea (the Republic of)3 LG chem Daejeon Korea (the Republic of)
Show AbstractWe introduce a highly cross-linked, mechanically strong polymer, namely, polyhexavinyldisiloxane (pHVDS) coating on PE separators using an initiated chemical vapor deposition (iCVD) process. The highly cross-linked but ultrathin pHVDS films can only be obtained by a vapor-phase process, because the pHVDS is insoluble in most solvents and thus infeasible with conventional solution-based methods. Moreover, even after the pHVDS coating, the initial porous structure of the separator is well preserved owing to the conformal vapor-phase deposition. The coating thickness is delicately controlled by deposition time to the level that the pore size decreases to below 7% compared to the original dimension. The pHVDS-coated PE shows substantially improved thermal stability and electrolyte wettability. After incubation at 140 °C for 30 min, the pHVDS-coated PE causes only a 12% areal shrinkage while the pristine separator shrinks as 90%. The superior wettability results in increased electrolyte uptake and ionic conductivity, leading to significantly improved rate performance. The current approach is independent of substrate materials and applicable to wide range of porous separators that suffer from thermal shrinkage and poor electrolyte wetting.
9:00 PM - EE4.3.18
MnO Nanoparticles with Low Degree of Crystallinity and Cation Vacancies as Anode for Li-Ion Capacitor
Chaofeng Liu 1,Guozhong Cao 1
1 Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences Beijing China,2 Department of Materials Science and Engineering University of Washington Seattle United States,1 Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences Beijing China
Show AbstractMnO nanoparticles with low degree of crystallinity and cation vacancies dispersed into porous carbon were designed and prepared through one step hydrothermal synthesis. The optimal synthesis conditions and the formation mechanism were explored in porous carbon encapsulated targeted MnO. Glucose as reducing agent and surfactant aided to introduce cation vacancies in MnO matrix, and provided carbon source to disperse MnO nanoparticles in a three dimensional spindle-like porous framework. Cationic vacancies benefit phase transition in conversion reaction, and together with a low degree of crystallinity may also provide more void space for ion diffusion (3.37×10-13cm2/s). Three dimensional porous carbon with a pore volume of 0.27 cm3/g, demonstrated a high electrical conductivity of 6.25 S/cm and offered fast pathways for charge transfer and penetration of electrolyte. Such synergistic structure endowed MnO with an excellent electrochemical properties including a much enhanced capacity of 650 mAh/g at a current density of 1000 mA/g. Li ion capacitors based on such MnO anode and activated carbon cathode achieved the maximum energy and power density of 220 Wh/Kg and 2608 W/kg, respectively, and capacitance retention was 95.3% after 3600 cycles at a rate of 5000 mA/g.
9:00 PM - EE4.3.19
A Single-Step Hydrothermal Synthesis of Vanadium Pentaoxides–Reduced Graphene Oxide Composite Electrodes for Enhanced Electrochemical Energy Storage
Sanju Gupta 1,Bryce Aberg 1
1 Western Kentucky University Bowling Green United States,
Show AbstractIntense research activity on alternative renewable energy is stimulated by continuously increasing global demand of electric energy. Electrochemical energy storage systems (EES) represent some of the most efficient and environmentally benign technologies and the need for next generation stable, high-performance electrode materials and architectures is the driving force. Graphene-decorated vanadium pentaoxide (V2O5) nanostructures namely, nanobelts (GVNBs) were synthesized via a low-temperature hydrothermal method in one-step approach. V2O5 nanobelts (VNBs) were formed in the presence of graphene oxide, a mild oxidant, which also enhanced the conductivity of GVNBs. From the surface x-ray photon spectroscopy analysis and several other structural characterization, the hydrothermally reduced graphene oxide (rGO) are inserted into the layered crystal structure of V2O5 nanobelts, which further confirmed the enhanced conductivity of the nanobelts. The electrochemical energy-storage capacity of GVNBs was investigated for supercapacitor applications. The specific capacitance Cs of GVNBs was evaluated using cyclic voltammetry (CV) and charge/discharge (CD) studies. The GVNBs having V2O5-rich composite, namely, V3G1 (VO/GO = 3:1), showed superior specific capacitance as compared with the other composites that is V1G1 (VO/GO = 1:1) and V1G3 (VO/GO = 1:3) and the pure component materials. Moreover, the V3G1 composite showed excellent cyclic stability and the capacitance retention of about > 80% was observed even after 2000 cycles. We gratefully acknowledge the financial support by WKU Research Foundation.
9:00 PM - EE4.3.20
Synthesis, Characterization and Electrochemical Properties of LiMPO4 (M = Fe, Mn, Co, Ni) Nanosheets for Enhanced Li+ Diffusion in Lithium-Ion Batteries
Gregory Neher 1,Samuel Baxter 1,Timothy Pope 1,Asma Sharafi 1,Andrew Hu 1,Tina Salguero 1
1 University of Georgia Athens United States,
Show AbstractLiMnPO4 (Li = Mn, Fe, Co, Ni) materials have received widespread interest as cathode materials for lithium-ion batteries due to their thermal and chemical stability, high coloumbic efficiencies, and environmentally friendly starting materials. However, these materials suffer from sluggish lithium diffusion and poor electron conductivity. Computational experiments show that Li+ ions travel out of the lattice through one-dimensional pathways in the [020] direction.
The goal of this research is to develop and understand synthetic routes that produce
< 10 nm thick LiMnPO4 nanosheets with the (020) plane, in order to improve the lithium diffusion into and out of the cathode. Two different strategies are used to develop nanosheets of LiMnPO4: reaction of LiMnPO4 microstructures with n-BuLi, and a nanosheet template method utilizing Mn3(PO4)2 ● 3H2O nanosheets. For the latter, Mn3(PO4)2 ● 3H2O nanosheets are synthesized by a facile room temperature reaction of Li3PO4 and a manganese salt. The Mn3(PO4)2 ● 3H2O nanosheets are hydrothermally reacted with different lithium salts under certain conditions, with the end goal of producing well defined, LiMnPO4 nanosheets. For the former, nanosheets with thickness < 3 nm and lateral dimensions in micrometers of LiMnPO4 were obtained by reaction with n-BuLi under an inert atmosphere. Ongoing research is focused on understanding the mechanism of the n-BuLi reaction during the formation of LiMnPO4 nanosheets, to eventually apply to other LiMPO4 systems.
9:00 PM - EE4.3.21
Core-Shelled SnO2/Polypyrrole Hollow Spheres Anodes with Enhanced Cyclic Performance for Lithium-Ion Batteries
Jujun Yuan 1,Chunhui Chen 1,Yong Hao 1,Chunlei Wang 1,Richa Agrawal 1
1 Florida International University Miami United States,
Show AbstractAmong currently studied anodes for Li-ion batteries (LIBs), SnO2-based materials have become one of the most promising materials, due to their high lithium-storage capacity (782 mAh g -1) and low potential of lithium alloying/de-alloying. In this research, SnO2/polypyrrole (PPy) core-shelled hollow spheres with good electrochemical performance were synthesized by liquid-phase deposition method using colloidal carbon spheres templates followed by an in situ chemical-polymerization route. As an anode in lithium ion batteries, the SnO2/PPy hollow sphere is capable of stable rate capability and long cycle life. The enhanced cycling stability SnO2/PPy nanocomposite is attributed to the unique core–shell structure and a possible synergistic effect between the PPy coating layer and the hollow SnO2 spheres. The PPy coating not only can improve the electron conductivity, but also prevents the possible pulverization of the hollow SnO2 sphere. Furthermore, the hollow space within the SnO2 nanostructures effectively mitigates the enormous volume change during charge–discharge cycling. Thus, the SnO2/PPy hollow spheres are able to provide a robust architecture for lithium-ion battery anodes.
9:00 PM - EE4.3.22
Reduced Graphene oxide-SnO2 Composite as an Effective Shield Against Electromagnetic Pollution and Anode Material for Li-Ion Battery
Monika Mishra 1,Avanish Pratap Singh 2,S Dhawan 3,Vinay Gupta 1
1 Department of Physics and Astrophysics Delhi University Delhi India,2 Department of Physics Atma Ram Sanatan Dharma College, University of Delhi New Delhi India3 Polymeric amp; Soft Materials Section CSIR-National Physical Laboratory New Delhi India
Show AbstractTin oxide nanoparticles architectured reduced graphene oxide composite (SnO2@RGO) have been synthesised by in-situ reduction of graphene oxide in the presence of stannous chloride. XRD and TEM studies show that tin oxide nanoparticles are anchored uniformly on the surface of reduced graphene oxide sheets. Microwave shielding performance of SnO2@RGO has been evaluated in X-band (8.2-12.4 GHz) range. A total electromagnetic interference shielding effectiveness of the order of 62 dB was achieved which is more than the required values (~30 dB) desired for techno-commercial applications. Along with this, the material shows promising performance as an anode material in Li-ion battery with a stable reversible specific capacity for more than 10 cycles of operation.
9:00 PM - EE4.3.23
Ultra-High Cycle Stability of ∂-MnO2 Nanowires in a PMMA Gel Electrolyte
Mya Le 1,Rajen Dutta 1,Reginald Penner 1
1 Chemistry University of California, Irvine Irvine United States,
Show AbstractMnO2 excels as hybrid electrical energy storage material, which intercalates lithium ion as a secondary battery electrode and instantaneously stores energy as electrical double layer capacitor. However, instability during the charge/discharge process has not been well studied. This work focuses on identifying a solid-state or gel electrolyte that mitigates the deleterious influences of air and water on cycling stability as well as studying degradation effects on MnO2 material after enduring this ultra long cycling. The main design used for this project is planar interdigitated array of delta phase MnO2. An electrolyte of 1.0M LiClO4 propylene carbonate (PC): PMMA mixture produces a gel electrolyte that can be drop-cast onto a planar interdigitated capacitor surface. These devices enable cycling to archive at least 100,000 cycles with 95% retention.
9:00 PM - EE4.3.24
Metal Oxide Nanowire-Microwave Exfoliated Graphene Oxide Hybrid for Lithium-Ion Battery
Mohammad Shuvo 1,Gerardo Rodriguez 1,Md Islam 1,Hasanul Karim 1,Navaneet Ramabadran 2,Juan Noveron 1,Yirong Lin 1,Hoejiun Kim 1
1 University of Texas at El Paso El Paso United States,2 University of California at Riverside Riverside United States
Show AbstractLithium ion battery (LIB) is a key solution to the demand of ever-improving, high energy density, clean-alternative energy systems. In LIB, graphite is the most commonly used anode material; however, lithium-ion intercalation in graphite is limited, hindering the battery charge rate and capacity. To date, one of the approaches in LIB performance improvement is by using porous carbon (PC) to replace graphite as anode material. PC’s pore structure facilitates ion transport and has been proven to be an excellent anode material candidate in high power density LIBs.In addition, to overcome the limited lithium-ion intercalation obstacle, nanostructured anode assembly has been extensively studied to increase the lithium-ion diffusion rate. Among these approaches, high specific surface area metal oxide nanowires connecting nanostructured carbon materials accumulation have shown promising results for enhanced lithium-ion intercalation. Herein, we demonstrate a hydrothermal approach of growing TiO2 nanowires (TON) on microwave exfoliated graphene oxide (MEGO) to further improve lithium-ion battery (LIB) performance over PC. This MEGO-TON hybrid not only uses the high surface area of MEGO but also increases the specific surface area for electrode−electrolyte interaction. Therefore, this new nanowire/MEGO hybrid anode material enhances both the specific capacity and charge−discharge rate. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used for materials characterization. Battery analyzer was used for measuring the electrical performance of the battery.The testing results have shown that MEGO-TON hybrid provides up to 80% increment of specific capacity compared to PC anode.
9:00 PM - EE4.3.25
Synthesis, Characterization and Electrochemical Analysis of Composite Cathode Material 0.5Li2MnO3-0.25LiMn2O4-0.25LiNi0.5Mn0.5O2 for LIB Applications
Monica Lopez de Victoria 1,Jifi Shojan 1,Lorraine Torres 1,Rajesh Katiyar 1,Ram Katiyar 1
1 Department of Physics and Institute for Functional Nanomaterials University of Puerto Rico San Juan United States,
Show AbstractStructural stability, environment friendliness, low cost as well as good electrochemical performances are the major requirements for cathode materials. Li2MnO3 based composite cathode materials are one of the widely investigated positive cathode materials due to their ability to provide high discharge capacity and good rate capability. We have synthesized cobalt-free layered- spinel composite cathode material 0.5Li2MnO3-0.25LiMn2O4-0.25LiNi0.5Mn0.5O2 (LLNMO) by sol-gel synthesis technique and surface characterized using XRD, Raman, SEM and EDX. Peaks corresponding to layered and spinel structures are identified by both XRD and Raman studies. SEM images depict the nano-sized particles and EDX data confirms the presence of constituent transition metals and oxygen. Active cathode material, carbon black and PVDF were mixed together in 8:1:1 ratio and spread on Al foil (current collector). Electrochemical studies were performed on coin cells, which were assembled in the Ar- filled glove box using Li as anode and spread material as cathode. LiPF6 with EC:DMC::1:2 ratio was used as the electrolyte. Cyclic voltammogram, electrochemical Impedance spectroscopy and charge discharge studies shows that the developed cathode material is a promising positive electrode for next generation Li ion batteries.
9:00 PM - EE4.3.26
Unravelling Structural Deformation and Electronic Properties of Intercalated Rechargeable Cathode from X-Ray Spectroscopy
Yufeng Liang 1,Luis De Jesues 2,Abhishek Parija 2,Sarbajit Banerjee 2,David Prendergast 1
1 The Molecular Foundry Lawrence Berkeley National Laboratory Berkeley United States,2 Department of Chemistry Texas Aamp;M University College Station United States
Show Abstract
Since the emergence of layered cobalt/nickel oxides in the Li-ion battery industry, transition metal oxides (TMOs) have thrived as promising candidates for cathode materials of rechargeable battery, not only because of their low cost but also due to their great flexibility in intercalation allowed by the transition metal d-shells. The next generation multivalent cathodes that are being intensively studied, such as V2O5 , MnO2, MoO3, can all exhibit a wide range of oxidation states when alien ions are inserted. Perhaps the only undesirable property introduced by the d-orbitas is its highly localized character that often hinders the electronic and ionic transport. Strongly correlated effects associated with d electrons can also lead to phase separation during the intercalation process. From the perspective, scanning transmission X-ray microscopy (STXM) is powerful characterization method for extracting local structural and electronic information. The spectral heat map created on thin nanostructured TMOs can provide valuable insight for intercalation mechanisms and possible phase segregations. However, the impact of intercalation on the X-ray spectroscopy of TMOs has scarcely been studied and reported in the literature, largely due to the difficulties in simulating X-ray spectroscopies for TMOs in the presence of strongly correlated effects. Previously, the spectral interpretation mainly rely on comparing TMOs with similar oxidation states. In this talk, I will present some recent advances in simulating X-ray spectroscopy made possible by rigorous many-body perturbation theory on first-principles level, which enables us to correlate structural and electronic properties with measured spectra on a reliable basis. Using these simulation technique, I will discuss the spectral fingerprint of change in coordination number, layer distortion, the emergence of magnetic order, and charge localization/ordering.
9:00 PM - EE4.3.27
Fabricating Si/Sn Nanoparticle Composite as High-Performance Lithium-Ion Battery Anodes
Lanlan Zhong 1,Chad Beaudette 1,Lorenzo Mangolini 1
1 Univ of California-Riverside Riverside United States,
Show AbstractDriven by the great need for improved energy storage solutions, several candidate materials for the development of high energy density anodes in lithium ion batteries (LIBs) have been intensively studied, especially silicon (theoretical capacity 3,579 mAh/g [1]) and tin (theoretical capacity 991 mAh/g [2]). Despite these efforts, a structure/material combination that satisfies the strict requirements of commercial utilization (high specific volume capacity, process scalability, low cost and abundant materials) has yet to be demonstrated.
In this contribution, we describe a novel and promising approach that may bring materials such as silicon and tin closer to commercial utilization. A critical review of the literature suggests that silicon nanostructures, while having high gravimetric capacity, are negatively affected by their low electrical conductivity. On the other hand, tin has good electrical conductivity but a theoretical capacity that is much lower than that of silicon. We have therefore designed and tested a silicon-tin composite structure which overcomes the limitations of each of these two materials. The anode was realized by mixing commercially available silicon nanoparticles, tin oxide nanoparticles and polyvynilpyrrolidone (PVP). An ethanol-based slurry was produced and coated onto copper foils via Mayer rod, followed by a single annealing step for reduction and carbonization. The thermal decomposition of PVP leads to the reduction of tin oxide to metallic tin. SEM, TEM and XRD analysis confirm that a uniform mixture of silicon and tin particles embedded into an amorphous carbon matrix is obtained. This electrode exhibits a stable storage capacity exceeding 1200mAh/g with nearly 80% first cycle coulombic efficiency. This performance is superior to that of the control samples produced using silicon nanoparticles alone and tin nanoparticles alone. Delithiation and lithiation peaks for both tin and silicon were observed, confirming that both components contribute to the device performance. Impedance spectroscopy suggests that tin nanoparticles not only contribute to the specific capacities but also act as conductive additive that guarantees the functionality of the nearby silicon nanoparticles. Weight loadings as high as 1 mg/cm2 have been tested with little variation in specific capacities.
[1] M. N. Obrovac and L. Christensen, Electrochemical and Solid State Letters 2004, 7, 93-96.
[2] Idota, Y., Kubota, T., Matsufuji, A., Maekawa, Y., Miyasaka, T. 1997, Science, 276 (5317), 1395-1397.
9:00 PM - EE4.3.28
Nanoparticles Jet Deposition of Silicon-Carbon Composite Anode for Energy Storage Applications
Giorgio Nava 2,Francesco Fumagalli 1,Fabio Di Fonzo 1
1 Center for Nano Science and Technology Milano Italy,2 Politecnico di Milano Milano Italy,1 Center for Nano Science and Technology Milano Italy
Show AbstractIn the field of energy storage lithium-ion batteries are widely considered the most mature technology (long cycle life, high gravimetric and volumetric density), though still insufficient to fulfil applications requirements. Public and private research heavily invested in the development of new high capacity anode materials in order to boost performances. Silicon with its low cost, earth abundancy and high theoretical capacity (4200 mAh/g) represents the most appealing alternative to the commercial graphite anodes (372 mAh/g). The use of silicon nanostructures, composed by aggregates below the critical size for crack propagation (300 nm) and with an optimized system of voids to withstand the volume change upon lithiation (up to 300%), combined with carbon coatings that increase the stability of the solid electrolyte interface (SEI) has been proven to be a suitable strategy to obtain superior cyclability and storage capacity. On the hand slurry based synthesis of composite anodes with superior volumetric capacity is studied as an industrial-compatible fabrication approach. The production of these optimized anode structures usually relies on complex multistep and low yield (45 mg/h) chemical synthesis methods, not suitable for large scale applications [1].
In the present work a novel large area (100 cm2), ultra-high yield (up to 200 mg/h) plasma-based deposition technique – Nanoparticles Jet Deposition (NANO JeD) – is presented for fabrication of composite silicon-carbon materials. The fabrication technique relies on a non-conventional ballistic approach that exploits two stages: a non-thermal dusty plasma synthesis environment (i) allowing for low temperature narrow size nanoclusters distribution control coupled with an impaction deposition stage (ii) where aerosol gas dynamic is controlled via nanoclusters-inseminated supersonic jet flow field. Gas phase control over the kinetic energy and directionality of nucleating nanoparticles allows tuning of material morphology ranging from compact films, to vertically aligned quasi 1D hierarchically organised structures with increased specific surface area, down to aerogel like structures.
Nano-composite lithium ion battery anodes are fabricated and characterized both in single step deposition, exploiting the described control over material porosity, and via slurry coating, employing aerogel-like deposition condition to collect silicon nanopowder at high rate (slurry: silicon nanoparticles/graphene nanoflakes/ binder).
Direct deposition approach proceeds via alternating an Ar-C2H2 plasma and Ar-H2-SiH4 plasma. The resulting architecture comprises of C-Si-C stacks, with a carbon bottom layer to improve electrical contact and adhesion to the copper collector, an intermediate layer of hydrogenated silicon with a tree-like nanostructured morphology for optimal volume adjustment upon swelling, and a top layer of carbon for the SEI stabilization.
1 C. K. Chan et al, ACS Nano 4, 1443-50 (2010)
9:00 PM - EE4.3.29
Graphene Nanosheets Supported FeP2 Hybrid as Lithium-Ion Anodes with Exciting High-Rate Performance
Zhaoxin Yu 1,Yue Gao 1,Adnan Mousharraf 1,Donghai Wang 1
1 The Pennsylvania State University State College United States,
Show AbstractFeP2 shares a similar electrical mechanism with FeP but shows a much higher theoretical capacity of 1366 mAh/g. However, comparing to FeP, FeP2 suffers from low electrical conductivity, which prevent its application as anode in lithium ion batteries. In order to improve its electrochemical performance, a highly-electronically-conductive matrix, building up by graphene nanosheets, is introduced into the system, where nano-sized FeP2 particles are uniformly distributed. Moreover, intimate contact between FeP2 and graphene nanosheets prevent loss of electrical contact during cycling. Benefiting from this structure, the FeP2-G hybrid anode exhibits high gravimetric specific capacity of ~960 mAh/g-FeP2 and excellent capacity retention even under extremely high current density of 6830 mA/g.
9:00 PM - EE4.3.30
Nano-Porous ZnCo2O4 Anode with High Capacity for Li-Ion Batteries
Wei-Ren Liu 1,Ji-Xuan Fu 1,Wei-Ting Wong 1
1 Chung Yuan Christian University Chung Li Taiwan,
Show AbstractIn this study, nano-porous ZnCo2O4 anode are synthesized via a hydrothermal method with subsequently different annealing temperature. X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are carried out to study the crystal structure, pore size distribution, surface morphology and characteristics, respectively. With increasing the sintering temperature, the morphology of ZnCo2O4 turns to sphere-like with porous structure. The as-prepared porous ZnCo2O4 nanospheres synthesized at optimal condition of 600 oC (600-ZCO) demonstrates high capacity of 1800 mAh/g and good retention performance of 1242 mAh/g after 30 cycles. The AC data shows that the 600-ZCO anode gives lower impedance compared to ZCO with other temperature. The porous nanosturcture and large surface area are responsible for superior performance. Moreover, nano-porous ZCO synthesized at 600 oC show larger capacity and better performance than other synthetic temperature of 500 oC and 700 oC, because of their superiority properties in structure.
9:00 PM - EE4.3.31
Synthesis and Characterization of Sulfur/Carbon/V2O5 Nanocomposite Cathode for Lithium-Ion Batteries
Long Kong 1,Izumi Taniguchi 1
1 Tokyo Inst of Tech Tokyo Japan,
Show AbstractThe demand for higher energy density LIBs for use in electric vehicles drives to develop new electrode active materials. Lithium–sulfur (Li-S) batteries are one of the most promising candidates to meet future market demands [1], as they possess a high theoretical capacity of 1,675 mAh g-1 and energy density of 2,500 kW kg-1. In addition, the low cost, natural abundance and environmentally benign nature of sulfur are also desirable properties that make it suitable for application in future energy materials [2]. Despite the above-mentioned advantages of sulfur, Li–S batteries have major drawbacks such as poor long-term performance and limited rate capability, which predominantly relate to the insulating nature of sulfur and lithium sulfides as well as the dissolution of polysulfides in electrolyte [3]. To overcome these issues, the most popular approaches are to encapsulate sulfur in the pores of carbon materials or a conductive polymer matrix. In this study, we present a quite different approach to prepare S/C/V2O5 composites and their physical and electrochemical properties were evaluated. The porous nanostructure V2O5 was firstly prepared by a novel spray pyrolysis method. The pore structure of obtained samples are analyzed based on N2 adsorption-desorption isotherm measurements, which indicated that the nanostructure V2O5 powders with pore size less than 200 nm could be prepared by the novel SP and the increase of NH4NO3 concentration in precursor solution could enlarge the porosity in V2O5 powders, especially the pore size between 20 to 80 nm. And then the as-prepared porous nanostructure V2O5 are mixed with acetylene black and S in a closed reactor at targeted ratio with argon gas before heat treatment. The effect of S content, heating temperature and heating time were investigated systematically. The electrode was prepared by mixing the active materials (S/C/V2O5 composites), conductive agent (acetylene black), and binder (polyvinylidene difluoride (PVdF)) in a weight ratio of 80:10:10. The effect of potential range on cycling performance were conducted by galvanostatic measurements. The results will be displayed on the conference in detail.
References
[1] Bruce et. al., Nat. Mater. 11 (2012), 19–29.
[2] Armand et. al., Nature, 451 (2008), 652–657.
[3] Manthiram et. al., Chem. Rev. 114 (2014), 11751–11787.
9:00 PM - EE4.3.32
Preparation of Nanoporous Magnesium by Physical Vapor Deposition
Han Wang 1,Xiping Song 1
1 University of Science amp; Technology Beijing Beijing China,
Show AbstractNanoporous metals have great potential applications in a number of fields due to the properties of the large surface area and rich surface chemistry, and compared with nanoparticles they also exhibit advantages of self-supported bi-continuous network structure and reusability. As one of the important respects, studies on the preparation methods of nanoporous metals have received more attentions in recent years. Several methods have been used to prepare nanoporous metals, such as template synthesis, surfactant mediated synthesis and dealloying. However, these methods have the shortage in the preparation of nanoporous materials of active metals, such as magnesium. In this paper a physical vapor deposition method was used to prepare the nanoporous magnesium, which has great potential applications in the field of hydrogen storage and magnesium-air battery. The results show that the nanoporous magnesium is successfully prepared in a vacuum of 10-1–10-4 Pa at 490 °C. The vacuum level, evaporation and deposition temperatures and substrate are found to be the key factors in the preparation of nanoporous magnesium. A mechanism of vacancy-assistant magnesium atoms segregation is proposed to explain the formation of nanoporous magnesium. This work should be meaningful in the study of the nanoporous metals.
Symposium Organizers
Mariappan Parans Paranthaman, Oak Ridge National Laboratory
Ayyakkannu Manivannan, USDOE/NETL
Yang-Kook Sun, Hanyang University
Donghai Wang, The Pennsylvania State University
Symposium Support
Aldrich Materials Science
EE4.4: Novel Electrolytes and Architectures
Session Chairs
Wednesday AM, March 30, 2016
PCC North, 100 Level, Room 124 A
10:00 AM - *EE4.4.01
A New Class of Single Ion Conducting Electrolyte (t+ = 1); Pure Alkali Cation Plastic Crystals
C. Austen Angell 1
1 Arizona State Univ Tempe United States,
Show AbstractThe importance of high power portable electrical energy needs no emphasis in a society as devoted to cell phones and laptop computers as ours. The current devices are almost all powered by lithium ion battery systems in which the ion charge flow that compensates the external electron flow, moves through a "salt in molecular liquid(s) solvent electrolyte - commonly immobilized in a gel matrix. The conductivity loss due to ion pairing in the current lithium ion battery technology, is quite severe but there has seemed to be little alternative. Here we offer an alternative by introducing a new class of ion-conducting medium in which the alkali cations are the only mobile species. These phases have structures intermediate between liquids and solids. Their conductivities are very high, relative to the available ionic liquids, indeed they conduct almost as well as the electrolyte solutions favored by current technology, while being free of their disadvantages. The new materials are salts of alkali cations in which the alkali cations take advantage of the rotation of their large partner anions to move freely through the waxy solid medium (glass-like transitions near -85 C). They maintain good conductivity at sub-zero temperatures. The anions of these new alkali salts contain the elements Si, S, and oxygen and in some cases Cl or other species. They are involatile, non-flammable, inoxidizable, and cheap, and there are many possible variations on the theme we outline.
10:30 AM - EE4.4.02
Hierarchical MoS2-Carbon Microspheres: A Robust Anode for High Performance Lithium Ion Battery
Gen Chen 1,Hongmei Luo 1
1 New Mexico State University Las Cruces United States,
Show AbstractWith higher theoretical lithium ion capacity of 670 mAh g–1 comparing with commercial graphite electrodes, molybdenum disulfide (MoS2) may be a promising alternative for lithium ion batteries (LIBs) because it offers unique layered crystal structure with Mo atoms sandwiched between two layers of closely packed S atoms and the MoS2 layers are linked by weak van der Waals interaction. The large and tunable distance between layers enables the anticipated excellent rate and cycling stability because they can promote the reversible lithium ion intercalation and de-intercalation without huge volume change and consequently prevents the pulverization of active materials during the repeated charge and discharge processes. However, either bulk or nanoscale MoS2 delivers poor conductivity for the electron/ion transfer, thus leading to obvious capacity loss after several cycles. Moreover, the MoS2 based electrodes provide high capacity through similar electrochemical redox reactions with lithium sulfide batteries in essence, which may also lead to their degradation by the polysulfide shuttling effect.
To overcome these barriers, numerous efforts have been devoted into the engineering of MoS2 nanostructures with optimized electrochemical performances. One effective strategy is to make the MoS2 into a few expanded layers, which provides a larger surface area, shorter lithium ions diffusion path and thus improved kinetics. On the other hand, combining conductive materials such as carbon or polymer with MoS2 will necessarily enhance the electron transport, cycling stability, structural integrity during the lithium-ion insertion/extraction processes. Herein, we prepared hierarchical MoS2-carbon microspheres via continuous and scalable ultrasonic nebulization route. The structure, composition, electrochemical properties are investigated in detail. The MoS2-carbon microspheres consist of MoS2 nanosheets with a few layers bridged by carbon (15 wt%), which separates the exfoliated MoS2 layers and prevents their aggregation and restacking. The novel architecture offers additional merits such as overall large size, high packing density, which promote their practical applications. The MoS2-C microspheres have been demonstrated to deliver excellent electrochemical performances in terms of low resistance, high capacity even at large current density, stable cycling performances, etc. The electrodes exhibited 800 mAh g–1 at 1000 mA g–1 over 170 cycles. At higher current density of 3200 mA g–1, a capacity of 730 mAh g–1 can be also maintained. The MoS2-C microspheres are practically applicable not only because of the continuous and large scale synthesis via current strategy, but also the robust and integrated architecture which ensures the excellent electrochemical properties.
10:45 AM - EE4.4.03
Understanding of the Electrochemical Mechanism of SnSb, a Promising Anode for LiB, by Operando Techniques#xD;
Philippe Antitomaso 1,Françoise Morato 1,Bernard Fraisse 1,Laure Monconduit 2,David Ayme-Perrot 3,Philippe Girard 4
1 Institut Charles Gerhardt de Montpellier UMR 5253 CNRS Montpellier France,1 Institut Charles Gerhardt de Montpellier UMR 5253 CNRS Montpellier France,2 Réseau sur le Stockage Electrochimique de l’Energie Paris France3 Hutchinson Chalette-sur-Loing France4 Total Paris France
Show AbstractIn order to respond to the development of new portable electronic devices or electric vehicles, specific energy of lithium ion batteries must be increased. In other words, carbon must be replaced by some new, more energetic negative electrode materials. Compared to the carbonaceous materials, tin and antimony metals possess very attractive theoretical capacities due to the high lithiated alloys that they form with Li (respectively Li7Sn2 and Li3Sb). Individually, tin and antimony show a poor cyclability versus Li due to their high volume changes during lithiation/delithiation process. In the alloys where all the active components can react with Li at different potentials in the charging/discharging process, such as SnSb (theoretical capacity of 825 mAh/g), the volume change occurs in a stepwise manner at various potentials, thus the unreacted component can accommodate the strain yielded by the reacted phase. Although the cycling stability of SnSb electrode was improved compared to Sb and Sn, it is still limited.1 Moreover the mechanism of lithiation/delithiation of SnSb was only briefly approached in the state of art2.
We decided to revisite this promising intermetallic electrode. A new flash synthesis was developed, which allows producing SnSb in 2 minutes, with a very simple preparation and a 100% yield. Moreover this synthesis is cheap that is making it a real asset for the industries.
We studied the electrochemical mechanism of the as-prepared SnSb by operando XRD and 119Sn Mössbauer experiments. The different potential plateaus of the SnSb/Li galvanostatic curve were related to the successive lithiation of antimony (Sb --> Li3Sb) at 0.8V, and at deeper depth of discharge to the lithiation of tin into successive LixSn phases. In charge, all steps are reversible to finally reform SnSb.
To improve the electrochemical performances in term of cyclability, both optimized electrode and electrolyte formulations were determined. The carboxymethyl cellulose, which recently showed to be the ideal binder for the electronic percolation in intermetallic electrodes leading to enhanced cyclability was used 3,4. Then an increased 400 mAh/g capacity was maintained after 300 cycles by using a 70/12/18 (SnSb/CMC/Cb) electrode formulation with a reasonable carbon content.5
1. Fan, L. al. Comparison between SnSb–C and Sn–C composites as anode materials for lithium-ion batteries. RSC Adv. 4, 62301–62307 (2014).
2. Fernandez-Madrigal, F. J. al. X-ray Diffraction , 7Li MAS NMR Spectroscopy and 119Sn Mössbauer Spectroscopy Study of SnSb-Based Electrode Materials. Chem. Mater. 14, 2962–2968 (2002).
3. Sougrati, M. T. al. J. Mater. Chem. 21, 10069 (2011).
4. Monconduit, L. Recent Advancements in the Conversion-Type Pnictide-Based Electrodes for Li-Ion Batteries. J. Phys. Chem. C 118, 10531–10544 (2014).
5. Park, C. M. al. A mechano- and electrochemically controlled SnSb/C nanocomposite for rechargeable Li-ion batteries. Electrochim. Acta 54, 6367–6373 (2009).
11:30 AM - *EE4.4.04
Epitaxial VO2(B) Thin-Films as Capacity-Fading-Free Electrodes
Shinbuhm Lee 1,Xiang Gao 1,Xiao-Guang Sun 1,Andrew Lubimtsev 1,Panchapakesan Ganesh 1,Tricia Meyer 1,Yunchao Li 1,Matthew Chisholm 1,Sung Seok Seo 2,John Freeland 3,Ho Nyung Lee 1
1 Oak Ridge National Laboratory Oak Ridge United States,2 University of Kentucky Lexington United States3 Argonne National Laboratory Argonne United States
Show AbstractB-phase VO2 [or VO2(B)] has an open framework and exhibits good electronic conduction at room temperature. Therefore, it been long regarded as a promising electrode material for Li-ion batteries owing to its high capacity, low cost, and abundant sources. However, fast capacity loss and poor high-rate performance of VO2(B) electrodes hamper the advancement of further developments, despite the fact that various VO2(B) nanostructures have been studied. It is, however, still unclear whether such poor performance is an intrinsic nature or associated with extrinsic causes. Therefore, it is importance to synthesize crystalline and phase pure VO2(B) thin films to explore the underlying mechanism responsible for the poor performance. By using pulsed laser epitaxy, we have successfully synthesized single crystalline B-phase VO2 films on conducting Nb-doped SrTiO3 substrates. Extraordinarily, even after 150 charge/discharge cycles by repeating lithiation/delithiation, almost no degradation of the initial capacity is observed. In this talk, we will present a systematic study, combining experimental and computational tools to reveal the synthesis, crystallographic structure, basic physical properties, and electrochemical performance. A combined study using x-ray diffraction, scanning transmission electron microscopy, x-ray photoelectron spectroscopy, and optical spectroscopy clearly shows good structural stability and a systematic variation of the electronic structure upon lithiation. Density functional theory (DFT) based calculations using DFT+U and hybrid-functionals identify the possible lithium absorption sites, the effect of lithiation on the electronic structure of VO2(B), and the theoretical limit for lithiation, in excellent agreement with experiments. In addition, ab initio molecular dynamics (AIMD) simulations provide further insights into ionic conductivity, indicating how Li ions take a preferential pathway for conduction, thereby providing a design strategy to more efficiently conduct Li ions through VO2(B). Similarly, we have also tested sodiation in VO2(B) for Na-ion batteries, which also reveals similar performance, and results will be presented.
*The work was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The theoretical work was performed as a user project at the Center for Nanophase Materials Sciences, which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, BES, U.S. DOE. Computations were performed at NERSC, a DOE Office of Science User Facility. Use of the Advanced Photon Source was supported by the U. S. Department of Energy, Office of Science, under Contract No.DE-AC02-06CH11357.
12:00 PM - EE4.4.05
In Situ Mapping of State-of-Charge Dynamics in Lithium-Ion Batteries
Ming Ke 1,Joon Sang Kang 1,Yongjie Hu 1
1 Mechanical and Aerospace Engineering University of California, Los Angeles Los Angeles United States,
Show AbstractDeveloping high energy density batteries has attracted intensive efforts during past decades. However, today’s batteries are prone to unexpected failure and performance degradations. Fundamental understanding of their in-situ dynamic properties during normal operation condition has become a critical demand and will lead to new solutions to improve battery performance and safety. So far, most traditional techniques are limited to external evaluation of the whole cell pack and are based on homogenous material modeling. As a result, a dynamic measurement on these key properties of each component material during the battery operation cycle remains challenging [1]. Here we develop an in-situ and non-invasive experimental apparatus by combining electrochemical control and high spatial and temporal resolution readouts, based on our recent progress on ultrafast optic and nanoscale electronic sensors [2, 3]. We demonstrated in-situ experimental measurement on battery electrodes to map multi-physical dynamic properties, including diffusion, heat dissipation, and mechanical evolution of lithium cobalt oxide electrodes in a battery charging/discharging cycle. These results show that in contrary to classical assumptions, a highly non-uniform dynamics are present for different battery charge states. Our results represent a key step toward establishing an in-situ property-structure relationship to predict and improve battery performance. Multi-scale modeling considering materials non-uniformity to improve battery safety will be discussed. This developed generic approach can be applied to various forms of batteries including lithium-ion, lithium-air, sodium-ion, lithium-sulfur systems.
Reference:
[1] Nature 488, 294-303 (2012).
[2] Nature Nanotechnology 10, 701-706 (2015).
[3] Nature Nanotechnology 7, 47–50 (2012).
12:15 PM - EE4.4.06
Synthesis and Characterization of Empty Silicon Clathrates for Anode Applications in Li-Ion Batteries
Kwai Chan 1,Michael Miller 1,Carol Ellis-Terrell 1,Candace Chan 2
1 Southwest Research Inst San Antonio United States,2 Arizona State University Tempe United States
Show AbstractSeveral processing methods have been developed and evaluated for synthesizing empty silicon clathrates. A solution synthesis method based on the Hofmann-elimination oxidation reaction was successfully utilized to produce about 10-20 mg of empty Si46.
First-principles computations were performed to identify the lithiation pathways, the structural and mechanical states of empty Si46 anode. These results were compared against those of Ba-stabilized and Na-stabilized metal-substituted silicon clathrate anodes. Empty Si46 anode was predicted to exhibit a higher capability compared to the Ba-stabilized and Na-stabilized silicon clathrate anodes as the Ba and Na guest atoms limit the number of Li ions that can be inserted into the host cavity.
Half-cells with a Si46 anode were successfully cycled for 1000 cycles at a C rate of 5.3. The capability of the Si46 anode in long-term test was 675 mAh/g at 4th cycle, but increased to 809 mAh/g at 50 cycles. The corresponding coulombic efficiency was better than 99%. The capacity dropped from 809 mAh/g to 553 mAh/g after 1000 cycles while maintaining a 99% coulombic efficiency. In comparison, a Ba8Al8Si38 anode could be cycled for about 200 cycles with a lower capacity and columbic efficiency.
A suite of ex situ techniques were employed to map the structural and mechanical state of the clathrate anodes as a function of lithiation/delithiation cycles for both Si46 and Ba8Al8Si38 anodes. Both the NMR and neutron diffraction data appeared to confirm the first-principles computations that Li-ions can be inserted and stored within the cage structure of silicon clathrates. Potential applications of silicon clathrates as anode materials in Li-ion batteries will be discussed.
12:30 PM - EE4.4.07
Cycling and Aging Studies of Li-Based Cathode Materials via Aberration-Corrected STEM
Patrick Phillips 1,Javier Bareno 2,Daniel Abraham 2,Robert Klie 1
1 Univ of Illinois-Chicago Chicago United States,2 Argonne National Lab Argonne United States
Show AbstractThe role of aberration-corrected scanning transmission electron microscopy (STEM) in materials characterization is examined with respect to layered-oxide cathode materials for battery applications. STEM-based methods are quickly becoming the most promising characterization tools for these materials, owed largely to the wide-range of techniques available on advanced STEM instruments, including the direct imaging of both heavy and light elements, and both energy-dispersive X-ray (EDX) and electron energy loss (EEL) spectroscopies. The current talk will focus on multiple Li-based, Mn-containing oxide cathode materials, for example, Li2MnO3 and Li(Ni0.5Co0.2Mn0.3)O2), characterized via STEM methods, in pristine, cycled, and in-situ irradiated states. The latter allows for single particle tracking of the dynamic processes occuring upon Li and O loss from the material, and is a form of accelerated ageing compared to the structural and electronic changes which occur upon electrochemical cycling. Various imaging modes, including high/low angle annular dark field (H/LAADF) and annular bright field (ABF), in conjunction with EELS/EDX, will be used extensively for this analysis, while parameters such as Mn valence, O presence, and light element occupation will be discussed.
12:45 PM - EE4.4.08
Development of Conjugated Organic Lithium Carboxylate with Improved Rate Capability for Li-Ion Battery
Lionel Fedele 3,Frederic Sauvage 3,Matthieu Becuwe 3
1 Laboratoire de Réactivité et Chimie des Solides Amiens France,2 Institut de Chimie de Picardie Amiens France,3 Réseau sur le Stockage Electrochimique de l'Energie Amiens France,
Show AbstractFor the past few years, conjugated organic lithium carboxylates have attracted particular attention owing to their low cycling potential between 0.7-1.4V vs Li+/Li[1], paving the way toward the substitution of copper-based current collectors by aluminum-based ones, inducing a reduction in cost and in the embodiment weight[2]. This family also presents several advantages: it is of low toxicity, it can be obtained from an eco-friendly process through CO2 sequestration, and the versatility of its structure allows to tune the potential. However, performances of this family still lag behind compared with graphite or LTO.
Different studies have been made over the last three years to optimize the conductivity and storage capacity of lithium carboxylate using formulation engineering[3] or crystallization[4] respectively. Aside from that, we focused our attention on the improvement of the rate capability which was achieved using a π–extended aromatic core instead of a simple benzene ring. As a result we obtained a drastic enhancement of the cycling rate until 2 Li+/h and 5 Li+/h using respectively a naphthalene[5] and a perylene[6] unit as stabilization center.
Here, we present a crystallized 2D-layered organic lithium carboxylate including a 4,4’-biphenyl core as network spacer used as negative electrode material for lithium ion battery. Deep and careful characterization was carried out to clearly identify atomic and material structures, using Solid-state 13C NMR and X-rays diffraction experiments jointly. This material exhibits improved rate capability displaying a gravimetric capacity of 190 mAh.g-1 after 25 cycles at 2 Li+ in one hour, and a reduction potential of 0.7V versus lithium.
Comparison with previous homologs (i.e. Dilithium terephthalate, Li2-BDC and Dilithium naphthalene dicarboxylate, Li2-NDC) possessing the same textural parameters reveals that such rate capability improvement is not only due to the extension of the conjugation inside the organic spacer and can be also ascribed to specific material properties such as crystallographic structure.
EE4.5: Solid Electrolytes and Novel Electrodes
Session Chairs
Wednesday PM, March 30, 2016
PCC North, 100 Level, Room 124 A
2:45 PM - *EE4.5.01
Self-Assembly Synthesis of Electrode Architectures for Energy Storage
Sheng Dai 2
1 Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge United States,2 Department of Chemistry University of Tennessee Knoxville United States,
Show AbstractCarbonaceous materials usually have a better electronic conductivity than metal oxides for meeting requirements in high-rate capability applications. However, both carbonaceous and metal-oxide materials suffer slow lithium diffusion rates within the corresponding electrode materials. This deficiency limits the high-rate capability for a number of electrode materials. Herein, we report a “brick-and-mortar” self-assembly synthesis of carbon and oxide composites as anode materials for lithium ion batteries. The objective of this work is to demonstrate that mesoporous carbons and oxides derived from soft-template synthesis not only entail a high storage capacity but also, most importantly, can be made through a “brick and mortar” self-assembly synthesis to have a significantly enhanced electronic conductivity. This enhanced electronic conductivity in 3D architectures is the key to providing high rate capability.
3:15 PM - EE4.5.02
Synthesis and Characterization of a New Fast Lithium-Ion Conductor Li7-x-yLa3Zr2-x-yNbxTayO12
Maria Maier 1,Thomas Mayerhoefer 2,Andreas Welzl 3,Maurizio Musso 1,Sonja Hoefer 2,Daniel Rettenwander 1,Juergen Popp 4,Juergen Fleig 3,Georg Amthauer 1
1 Department of Chemistry and Physics of Materials Paris Lodron University of Salzburg Salzburg Austria,2 Leibniz Institute of Photonic Technologies Jena Germany3 Institute for Chemical Technologies and Analytics Vienna University of Technology Vienna Austria2 Leibniz Institute of Photonic Technologies Jena Germany,4 Institute of Physical Chemistry and Abbe Center of Photonics Friedrich Schiller University Jena Jena Germany
Show AbstractTechnologies for renewably generated energy and its storage in delocalized stationary systems as well as portable devices belong to the important contemporary challenges. All-solid-state lithium-ion batteries have therefore been extensively studied in recent years. They offer high volumetric and gravimetric energy densities at high power densities, comply with safety requirements, and provide further desirable properties like thermal and mechanical stability.
Cubic, garnet-like ceramics Li7-x-yLa3Zr2-x-yNbxTayO12 (0 ≤ x, y ≤ 2) (LLZNTO) are promising solid-state electrolytes, not least because of their good chemical stability against various electrode materials, especially Li metal. A cubic structure is a necessary, although not a sufficient, condition for high ionic conductivity in these oxides. Not all LLZNTOs are cubic at ambient conditions. The endmember Li7La3Zr2O12 and very low substituted samples exhibit a tetragonal structure. The phase transition occurs around x+y = 0.25 in Li7-x-yLa3Zr2-x-yNbxTayO12, depending on the synthesis conditions.
Practical applications in all-solid-state batteries demand electrolytes with ionic conductivities σ ≥ 10-4 Scm-1. Generally speaking, the ion conductivity is a function of the amount of charge carriers and their mobility in a compound. In LLZNTOs low substitution concentrations (i.e. high lithium ion contents) and dense sintered materials (i.e. a highly disordered lithium-sublattice and a low grain-boundary resistance) promote the ion conductivity.
This study presents the preparation and characterization of fast Li-ion conductors LLZNTOs. The solid solutions are characterized by standard methods like powder XRD and SEM. Ionic conductivities are measured by conventional EIS. A special focus of the characterization lies on Raman-spectroscopy and FTIR-spectroscopy, because only very few articles concerning vibrational spectroscopy and LLZNTOs have been published so far.[1,2,3,4] Raman measurements with different laser wavelengths, at various (especially low) temperatures, and with an electrically gated (100 ps) Raman equipment for suppressing fluorescence will elucidate the LLZNTO-structure. FTIR data from the reststrahlen region between 85 – 900 cm-1 are gained by dispersion analysis, which gives further insight into the LLZNTO-structure.
Acknowledgements: The authors thank the team of TimeGate Instruments Ltd. (Oulu, Finland) for the Raman measurements with luminescence rejection. Andreas Reyer is kindly acknowledged for assistance in recording Raman spectra at the University of Salzburg. This work is financially supported by the Austrian Science Fund (FWF).
[1] Larraz G., Orera A., Sanjuán M.L., J. Mater. Chem. A, 2013, 1, 11419.
[2] Tietz F., Wegener T., Gerhards M. T., et al., Solid State Ionics, 2013, 230, 77.
[3] Thompson T., Wolfenstine J., Allen J. L., et al., J. Mater. Chem. A, 2014, 2, 13431.
[4] Mukhopadhyay S., Thompson T., Sakamoto J., et al., Chem. Mater., 2015, 27, 3658.
3:30 PM - EE4.5.03
Enhancing Ionic Transport through the Mesoscopic Scale: A Case Study of the Perovskite Solid Electrolyte for Li Batteries
Miaofang Chi 1,Cheng Ma 1,Karren More 1,Ce-wen Nan 2,Nancy Dudney 1
1 Oak Ridge National Laboratory Oak Ridge United States,2 Tsinghua University Beijing China
Show AbstractFacile ionic transport in solids is crucial in many energy storage/conversion technologies, such as batteries, fuel cells, and supercapacitors, etc.. Precisely determining ionic transport mechanism is the prerequisite for rational design of solid-state ionic conductors. For decades, the research on this subject has primarily been focused on understanding ion transport pathway based on unit cell structures. In this presentation, we show that the mesoscopic scale features could play an important role in facilitating ionic conduction in solids. In a prototype Li-ion-conducting solid electrolyte, (Li0.33La0.56)TiO3 (LLTO), a unique mesoscopic ionic ordering framework was discovered by the state-of-the-art scanning transmission electron microscopy, and proved to be key leading to an exceptional ion conduction in this material. Combined with theoretical calculations, this observation led to a fundamentally different ionic transport mechanism, which successfully reconciled the long-standing structure-property inconsistency in this material. The present work underlines the importance of studying ionic transport mechanism at a complete set of length scales, and provides broad insights into designing solid-state ionic transport mechanisms for different charge carriers.
3:45 PM - EE4.5.04
Structural and Ionic Transport Properties of LISICON and NASICON Solid Electrolyte Materials
Yue Deng 1,Chris Eames 2,Jean-Noel Chotard 1,Oliver Pecher 3,Clare Grey 3,Christian Masquelier 1,Saiful Islam 2
1 Laboratoire de Réactivité et Chimie des Solides Université de Picardie Jules Verne Amiens France,2 Department of Chemistry University of Bath Bath United Kingdom3 Department of Chemistry University of Cambridge Cambridge United Kingdom
Show AbstractSolid electrolytes that are chemically stable and have a high ionic conductivity would dramatically enhance the safety and operating lifespan of rechargeable lithium batteries [1,2]. Here, we apply a multi-technique approach to the LISICON ((1−z)Li4SiO4−(z)Li3PO4) and NASICON (Sc3+ doped Na3Zr2Si2PO12 and Na2Zr2SiP2O12) type materials with the aim of developing solid electrolytes with enhanced ionic conductivity for use in all solid state batteries. In the solid solutions between Li4SiO4 and Li3PO4, previously unidentified superstructure and immiscibility features in high-purity samples were characterized by X-ray and neutron diffraction across a range of compositions. Ionic conductivities from AC impedance and large-scale molecular dynamics (MD) simulations are in good agreement, showing low values in the parent phases but orders of magnitude higher conductivities (10−3S/cm at 573K) in the mixed compositions. The MD simulations reveal new mechanistic insights into the mixed Si/P compositions in which Li-ion conduction occurs through 3D pathways and a cooperative interstitial mechanism; such correlated motion is a key factor in promoting high ionic conductivity [3]. Solid-state NMR experiments reveal enhanced local Li-ion dynamics and atomic disorder in the solid solutions, which are correlated to the ionic diffusivity. The NASICON material Na3Zr2Si2PO12 (NZSP) has already shown application in all-solid-state batteries, with the conduction properties modified by doping on the transitional metal site [4,5]. Here, two systems: Na3ScxZr2-xSi2-xP1+xO12 and Na2ScxZr2-xSi1-xP2+xO12 have been studied. Neutron diffraction shows that besides NZSP, all samples can be indexed in a rhombohedral structure at 300K. High ionic conductivities (10-3 to 10-2S/cm at 573K) are exhibited from both MD simulations and AC Impedance. Continuous diffusion pathways are found with ion hopping and site exchange between Na(1) and Na(2) sites. These unique insights will be valuable in developing strategies for understanding transport mechanisms and optimizing ionic conductivity, as well as identifying novel solid electrolyte materials.
References
1. N. Kamaya et al., Nat. Mater. 2011, 10, 682
2. C. Masquelier, Nat. Mater. 2011, 10, 649
3. Y. Deng et al., J. Am. Chem. Soc., 2015, 137, 9136
4. F. Lalère et al., J. Power Sources, 2014, 247, 975
5. F. Lalère et al., J. Mater. Chem. A, 2015, 3, 16198
4:30 PM - *EE4.5.05
Development of High Area Loading and Stable Sulfur Electrode through Interface Functionality Design for Lithium Sulfur Battery
Gao Liu 1,Min Ling 1
1 Energy Storage and Distributed Resource Division, Energy Technologies Area Lawrence Berkeley National Laboratory Berkeley United States,
Show AbstractHigh area loading of sulfur is a critical parameter to achieve high energy-density Li-S battery. Interface properties between electrode and electrolyte play an important role in these batteries. Sulfur species dissolution, precipitation and phase transformation during the charge and discharge process strongly affect the performance of lithium sulfur (Li-S) batteries. In this work, we examine the chemical functionalities that are important to stabilize sulfur electrode. As an example, binders with different functionalities, which differs both in chemical and electrical properties, are employed to modify the interface between the conductive matrix and electrolyte. The phase transformation of sulfur species at this interface is studied in detail. Remarkable differences are observed among sulfur cathodes with different binders modified interface. More solid-phase sulfur species precipitation is observed with binders that have strong affiliate functional groups, like poly(9, 9-dioctylfluorene-co-fluorenone-co-methylbenzoic ester) (PFM) and poly(vinylpyrrolidone) (PVP), in both fully charged and discharged states. Also, the improved conductivity from introducing conductive binders greatly promotes sulfur species precipitation. These findings suggest that the contributions from functional groups affinity and binder conductivity lead to more sulfur transformation into the solid phase, so the shuttle effect can be greatly reduced, and higher sulfur area loading and better cycling stability can be obtained.
5:00 PM - EE4.5.06
A Low-Cost Carbon Composite Anode Material from Recycled Waste Tires for Lithium-Ion Batteries
Joseph Gnanaraj 1,Rich Lee 1,Alan Levine 1,Jonathan Wistrom 2,Skyler Wistrom 2,Yunchao Li 3,Jianlin Li 5,Amit Naskar 4,Mariappan Paranthaman 3
1 Energy Division RJ Lee Group Monroeville United States,2 Practical Sustainability Maryville United States3 Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge United States5 Energy amp; Transportation Science Division Oak Ridge National Laboratory Oak Ridge United States4 Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge United States
Show AbstractThe growing automotive industry creates large amount of waste tires which lead to increasing environmental and economic issues throughout the world. Recently, Oak Ridge National Laboratory, (ORNL) reported a significant breakthrough technology that is capable of converting used tires into high grade Lithium Ion (Li-Ion) battery carbon at the cost of less than half the commercial graphite. RJ Lee Group has licensed the technology from ORNL and carried out this work in collaboration and demonstrated the production of tire-derived microporous carbon composite (TCC) anode material in large quantities from recycled waste tire using sulfonation followed by pyrolysis. TCC is used as a potential anode material in Li-Ion batteries. Cryo-shred tire rubber with 18/12 mesh size feedstock was digested in a hot oleum bath to yield sulfonated rubber slurry which was then filtered, washed, and pyrolized at 1100 °C in a nitrogen atmosphere. The manufactured TCC is low cost, highly pure >99.9% with good electrochemical properties and can replace the existing graphite anode in Li-Ion batteries which in turn will reduce the battery cost by ~12%. Furthermore, The United States does not currently mine graphite and in that respect TCC will become a significant domestic source of anode material for battery application. Li-Ion cells having TCC anode in a half-cell configuration exhibited an initial first cycle capacity of 457 mAh/g at 0.38 mAh/cm2 with more than 60% coulombic efficiency. Further cycling showed higher reversible capacity of 300 mAh/g when the current rate reduced to 0.15 mA/cm2 and achieved 425 mAh/g capacity at 0.02 mA/cm2 with nearly 100% coulombic efficiency which is 91% of the first discharge capacity and that demonstrates the diffusion controlled particle size effect in the electrochemical process. Our recent studies on Li-Ion pouch full cells using TCC anode and NMC 532 cathode showed stable cycle life with 40 mAh capacity up to 2.3mA/cm2 current rates.
5:15 PM - EE4.5.07
Solid-Like Biomimetic Ion-Channel Electrolytes for Lithium Metal Batteries
Addis Fuhr 2,Li Shen 1,Hao Bin Wu 1,Xiao-Feng Wang 3,Anastassia Alexandrova 4,Yunfeng Lu 1
1 Chemical and Biomolecular Engineering University of California, Los Angeles Los Angeles United States,2 C-PCS Los Alamos National Laboratory Los Alamos United States,1 Chemical and Biomolecular Engineering University of California, Los Angeles Los Angeles United States3 School of Chemistry and Chemical Engineering University of South China Hengyang China4 Chemistry and Biochemistry University of California, Los Angeles Los Angeles United States
Show AbstractThe high theoretical capacity of lithium metal (3860 mAh g-1) provides great promise for increasing the driving range of electric vehicles (EVs). Development of solid electrolytes with conductivity surpassing 10-4 S/cm, high electrochemical stability, and ability to block dendrite growth are pivotal to the future of the Li anode. However, inability to improve solid electrolyte conductivity without affecting other desirable properties has remained a challenge. Improvement of ionic conductivity in ceramics (up to 10-3 S cm-1) typically results in alteration of the electronic structure and lowered electrochemical stability, increased reactivity towards Li metal, and/or increased sensitivity to both moisture and oxygen. Enhancement in polymer electrolyte conductivity, conversely, leads to increased chain-mobility, resulting in loss of mechanical strength, inhibiting the ability to block dendrite growth. In the case of gel electrolytes, the additional safety concerns of crush and nail penetration leading to leakage and fire are also present.
We report a novel biomimetic approach that allows lithium conductivity to be enhanced without significant alteration of electrochemical and flame stability. Molecularly ordered porous scaffolds are used for adsorption of liquid-electrolytes. Anions from the lithium salt bind to channel walls in order to mimic the negatively charged glutamate layers found in ligand-gated biological Na+ or K+ channels. The combined effects of crystalline polar side-chains and pore sizes being smaller than the Debye screening length of the liquid media allow for the efficient screening of the anion’s negative charge and elimination of contact ion-pairs. The solvation of Li ions and efficient charge separation allow Li ions to achieve high mobility through the negatively charged channels. We report the synthesis of several structures with experimental conductivities surpassing 10-3 S/cm, electrochemical stability nearing 5V vs. Li/Li+, high chemical stability against Li metal, low flammability, and conduction mechanism studies via quantum mechanical modeling. We further integrate the solid-like electrolyte membrane into a LiFePO4/Li battery cell under room temperature operation. The resulting high specific capacity and long cycling life indicate its promising electrochemical stability. Moreover, with the facile modification procedure and superior performance, the development of biomimetic ion-channels could allow for accelerated discovery of new fast-ion conductors for energy storage technology.
5:30 PM - EE4.5.08
Temperature Dependence of Electrolyte Oxidation at Charged NCM Cathode Surface
Adam Tornheim 1,Meinan He 2,Chi-Cheung Su 1,Chen Liao 1,Javier Bareno 1,Ira Bloom 1,Zhengcheng Zhang 1
1 Argonne National Laboratory Lemont United States,1 Argonne National Laboratory Lemont United States,2 Worcester Polytechnic Institute Worcester United States
Show AbstractThe pursuit of high energy density lithium-ion batteries is of great interest to electric vehicle manufacturers. One approach to improve the energy density is to use higher voltage cathodes (>4.5 V vs. Li/Li+). However, as the cathode voltage is increased, the oxidation rate of the electrolyte increases, leading to electrolyte depletion and interfacial impedance rise, both contributing to the cell performance degradation. While this performance degradation can be identified with high-voltage cycling tests, a comprehensive understanding of the relationship between voltage and temperature on electrolyte decomposition rates at the cathode surface remains unclear.
In this work, the degree of electrolyte (1.2 M LiPF6 EC/EMC (3/7 by weight)) oxidative decomposition as a function of temperature was measured through the use of high voltage potentiostatic holds. For these experiments, lithium-ion cells with a low-loading NCM523 cathode (4.08 mg/cm2) and a high-loading Li4Ti5O12 anode/reference with an N/P ratio of approximately 2.5 were fabricated and used for this study. A systematic protocol incorporating formation, aging (potentiostatic holds at room temperature, 35oC, 45 oC, and 55 oC), and post-aging electrochemical evaluation was implemented. The results indicate the accelerating effect of temperature on electrolyte oxidation at elevated voltage, and the subsequent effect of this electrolyte oxidation on cell performance, including capacity retention, rate performance, and electrochemical impedance. Cathode surfaces were evaluated with a variety of ex-situ characterization techniques to analyze the chemical nature of the decomposition products. With this new protocol to evaluate oxidation stability of the state-of-the-art electrolyte at the cathode surface, the ability of intrinsically stable electrolytes and novel electrolyte additives to passivate the surface can be more accurately evaluated.
Acknowledgements
Support from the Vehicle Technologies Program, Hybrid and Electric Systems, David Howell and Peter Faguy at the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, is gratefully acknowledged. This work was performed under the auspices of the DOE Office of Vehicle Technologies, under Contract No. DE-AC02-06CH11357.
5:45 PM - EE4.5.09
Hybridization of Transition Metal Carbides (MXene) and Oxides for High Performance Li-Ion Storage
Mengqiang Zhao 1,Michelle Torelli 1,Chang Ren 1,Michael Ghidiu 1,Michel Barsoum 1,Yury Gogotsi 1
1 Drexel Univ Philadelphia United States,
Show AbstractTwo-dimensional (2D) materials, such as graphene, are attractive candidates for energy storage devices due to their large areas of electrochemically-active surfaces. Recently, MXenes, a new family of 2D carbides discovered at Drexel University in 2011, have shown promise for electrodes in Lithium-ion batteries and supercapacitors. The goal of this study was to determine if a combination of MXenes, which have high metallic conductivity but moderate capacity, and transition metal oxides (TMOs) with high lithium storage capacity but poor conductivity may result in improved performance.
Three different methods, including alternating filtration, spray coating, and in-situ growth, were employed to achieve the hybridization of Ti3C2 MXenes and TMOs. Flexible and free-standing Ti3C2/TMO papers were obtained. In these composites, the 1-nm thin flakes of Ti3C2-MXene provide superior conductivity, ensure mechanical integrity and flexibility, as well as some Li-ion storage capacity; the TMOs (e.g. Co3O4, NiCo2O4) nanosheets/nanorods serve as spacers between MXene flakes to improve the accessibility of electrolyte ions and provide additional capacity. The synergetic effect of the two materials leads to much improved performance compared to pure Ti3C2 or TMOs. The Ti3C2/TMO paper electrodes containing alternation layers of carbide and oxide achieved high reversible capacities of 1200-1400 mAh/g at 0.1C (10-hrs discharge), 4 times higher than commercial graphite anodes. These paper electrodes also exhibited excellent rate performance and superior cycling stability. A highly stable capacity around 500 mAh/g was retained for >1000 cycles at 1C rate (1-hr charge/discharge), with no obvious decay. This work provides a simple, scalable, and effective strategy for the fabrication of advanced electrode materials that can be used in wearable or structural electrochemical energy storage and conversion systems.
EE4.6: Poster Session II
Session Chairs
Thursday AM, March 31, 2016
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - EE4.6.01
N-Doping Effect of di-Vacancy Graphene on Oxygen Reduction Reaction (ORR) of Lithium-Air Battery
Young Hoon Yoon 1,Ji Hye Lee 1,Seung Geol Lee 1
1 Pusan National University Busan Korea (the Republic of),
Show AbstractThe development of energy storage is necessary to improve operating time for electric devices. The electric vehicles, which draw their power from batteries, require huge energy storage for long driving range. Rechargeable Li-air batteries (LABs) have been reviewed as an energy source due to their high theoretical energy density, which is comparable with that of the gasoline engine. However, Li-air batteries (LABs) have intractable problems such as pore clogging and aggregation of lithium oxides (LixO2), which caused limitations about the lifetime and cycling efficiency. The functionalized carbon-based materials have been designed to overcome these issues. Among diverse functionalized carbon materials, graphene, a single layer of graphite, have drawn intensive attention as an electrode material in the battery system due to extraordinary properties such as high electrical, thermal conductivity. N dopants and defects in graphene may be formed during the growth process. These dopants and defects can modify the activity, which affect the adsorption behavior of lithium oxides (LixO2). Thus, understandings of the effect of N dopants and defects play a vital role on revealing the mechanism of oxygen reduction reaction (ORR). To investigate the effects of N dopants and defects on the oxygen reduction reaction (ORR) on graphene, we studied the adsorption behavior of lithium oxides (LixO2) on N-doped di-vacancy graphene by calculating the adsorption energy and electronic properties using density functional theory. For N-doped di-vacancy graphene, the adsorption energy improves with the increasing number of N atoms.
Acknowledgement
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2014R1A1A1004096).
9:00 PM - EE4.6.02
Conductive Interwoven Bamboo Carbon Fibers Membrane for Li–S Batteries
Xingxing Gu 2,Yanglong Hou 2,Shanqing Zhang 1
1 School of Environment Griffith Univ Gold Coat Australia,2 Department of Materials Science and Engineering, College of Engineering Peking University Beijing China,2 Department of Materials Science and Engineering, College of Engineering Peking University Beijing China1 School of Environment Griffith Univ Gold Coat Australia
Show AbstractBeing simple, inexpensive, scalable and environmentally friendly, biomass biochars have been attracting enthusiastic attention for lithium-sulphur (Li−S) batteries application. Natural bamboo, as a sustainable precursor, is used to prepare porous bamboo carbon fibers (BCFs) that are subsequently interwoven into a BCF membrane (BCFM) as a captor interlayer for the lithium polysulfide intermediates between the sulfur cathode and the separator in Li–S batteries. On one hand, the interwoven BCFs offer efficient conductive networks. On the other hand, the pores of the BCFM facilitate fast mass transport of electrolyte and Li ions and accommodate severe volume changes of the sulfur cathode during charge/discharge processes. Furthermore abundant macro/micro porous structures of BCFs provide substantial adsorption capability to remarkably suppress the formation of Li2S2/Li2S layer on the cathode and extend the lifetime of electrode by successfully confining sulfur within the carbon networks. Consequently, Li–S batteries with the BCFM deliver excellent electrochemical performances with a high coulombic efficiency (ca. 98%), low capacity fade at only 0.11% per cycle, and long-term cyclability over 300 cycles at a high charge/discharge rate of 1 C. This green, low cost BCFM can provide an attractive alternative for large-scale commercialization of Li–S batteries
9:00 PM - EE4.6.03
Enhanced Efficiency of Sulfur Cathode via Cryogenic Grinding of Glassy-Like Sulfur for Application in Li-s Batteries
Milos Krbal 1,Tomas Kazda 2,Miloslav Pouzar 3,Jan Macak 1,Andrea Strakova Fedorkova 4,Jiri Vondrak 2
1 Center of Materials and Nanotechnologies (CEMNAT) University of Pardubice Pardubice Czech Republic,2 Institute of Electrotechnology Brno University of Technology Brno Czech Republic3 Institute of Environmental and Chemical Engineering University of Pardubice Pardubice Czech Republic4 Department of Physical Chemistry P. J. Safarik University Kosice Slovakia
Show AbstractThe ever-increasing demand for better energy storage systems with high energy density utilized in electrical vehicles and devices for renewable energy storage from solar and wind drawn the interest in low-cost rechargeable Lithium Sulfide batteries. Sulfur, easily available element in nature, can reach theoretical capacity 1672 mAh/g which is far above that of conventional insertion compound cathodes such as LiFePO4 (LFP) – 170 mAh/g, LiCoO2 (LCO) – 274 mAh/g, Li-rich nickel-cobalt manganese oxide (NMC) - 277 mAh/g and thus it makes sulfur to be a suitable candidate for high capacity cathode for Lithium-based batteries [1]. In contrast to transient metal oxide cathodes, the sulfur-based cathode operates at lower voltage, typically ~ 2.1 V. On the other hand the final battery performance is compensated by the high energy density of 2600 Wh/kg.
However, a few challenges still remain to be solved in order to transfer this technology in mass production. One of the main difficulties is the self-discharging effect that occurs due to the polysulfide shuttle phenomenon resulting in capacity loss and low Columbic efficiency. Recently, it has been demonstrated some possibilities how to overcome these persistent problems by mixing of sulfur with a high amount of conductive additives such as a carbon or conductive polymers [2], formation of sulfur-based nanocomposites [3, 4] or core-shell [5] and yolk-shell nanoparticles [6].
Here we report that the capacity loss can be significantly suppressed when sulfur is prepared as amorphous (undercooled plastic) and subsequently is grinded under cryogenic conditions at temperature of liquid nitrogen. Even though the sulfur within the subsequently prepared cathode was already in the crystalline form, it retained a capacity ~ 600 mAh/g after 50 charge/discharge cycles at 0.2 C with the capacity loss ~ 3% [7]. That is ~ 20 times less than in the case of conventionally prepared sulfur cathode. The SEM analysis of the sulfur particles performed under cryogenic grinding showed particle size distribution peaking at ~ 3 µm. Difference in electrochemical behavior of differently prepared sulfur cathodes will be discussed.
References:
[1] B. L. Ellis, K. T. Lee, L. F. Nazar, Chem. Mat. 22, (2010) 691.
[2] Y. Fu and A. Manthiram, Chem. Mat. 24, (2012) 3081.
[3] X. Ji et al. Nature Mat. 8, (2009) 500.
[4] G. Zhou et al. Nano Energy 11, (2015) 356.
[5] Z. W. Seh et al. Nat. Commun. 4, (2013) 1331.
[6] Z. Lin et al. ASC Nano. 7, (2013), 2829.
[7] T. Kazda at al., Electrochem. Commun., in preparation.
9:00 PM - EE4.6.04
Synthesis and Characterization of Substituted Garnet and Perovskite Based Lithium-Ion Conducting Solid Electrolytes
Maria Abreu Sepulveda 2,Dominique Williams 2,Ashfia Huq 3,Chetan Dhital 3,Yunchao Li 3,Mariappan Parans Paranthaman 3,Karim Zaghib 4,A. Manivannan 5
1 University of Rochester Rochester United States,2 National Energy Technology Laboratory Morgantown United States,2 National Energy Technology Laboratory Morgantown United States3 Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge United States4 Hydro-Québec Quebec Canada5 West Virginia University Morgantown United States
Show AbstractThe effect of B-site substitution in the phase formation and ionic conductivity for a family of ceramic oxides with garnet and perovskite structures was studied by neutron diffraction and electrochemical impedance spectroscopy. Titanium, tantalum-substituted Li7La3Zr2-xAxO12 (LLZO, A= Ta, Ti), and chromium-substituted Li0.5La0.5Ti1-xCrxO3 (LLTO) both of which are lithium-ion (Li-ion) conducting solid electrolytes, were prepared by conventional solid state reaction and the Pechini method, respectively. The desired crystal phases were obtained by varying the calcination temperature and time, as well as the substitution concentration. Substitution-induced transitions in crystal phases are a significant solid electrolyte property since Li+ mobility and structure density are affected for certain phases. Neutron diffraction data shows the formation of a predominant cubic phase in the case of Ta-LLZO, and monoclinic phase with minor impurity peaks for Cr-LLTO. Ionic conductivity at room temperature of Ti-LLZO, Ta-LLZO, and Cr-LLTO were found to be 2.3 x10-5 S cm-1, 1.27 x10-4 S cm-1, and 10-4 to 10-3 S cm-1, respectively. Doping chromium in LLTO (Li0.5La0.5Ti0.9Cr0.1O3 and Li0.5La0.5Ti0.94Cr0.06O3) showed an improvement in the conductivity in the range as well as good mechanical strength. We will report in detail about the synthesis and characterization of B-site substituted garnet and perovskite based solid lithium ion conducting electrolytes.
9:00 PM - EE4.6.05
Synergistic Sodiation of Transition Metal Oxide and Carbon Nanotubes (CNTs) Nanostructured Composite Electrodes for Sodium-Ion Battery
Qianqian Li 1,Jinsong Wu 1,Vinayak Dravid 1
1 Department of Materials Science and Engineering, The NUANCE Center Northwestern University Evanston United States,
Show AbstractReplacing lithium with sodium in batteries for energy storage is of enormous interest, especially from practical and economic considerations.1, 2 However, it has proved difficult to achieve competitive figures of merit for sodium-ion batteries due to lack of detailed understanding of the reaction mechanism(s). Herein we report sodium electrochemical conversion reaction with Co3O4 nanoparticles decorated on carbon nanotubes (Co3O4/CNT) utilizing in-situ TEM, down to the atomic-scale. We observe synergetic effects of the two nanoscale components, which provide insights into a new sodiation mechanism, facilitated by Na-diffusion along CNT backbone and CNT-Co3O4 interfaces. A thin layer of amorphous low conductivity Na2O forms on the CNT surfaces at the beginning of sodiation. This results in an anisotropic sodiation, wherein the reaction front shifts to the interface between the nanoparticles and CNTs - yet sustaining high electrical/ionic transport. Conversion reaction results in the formation of ultrafine metallic Co nanoparticles and polycrystalline Na2O, and surprisingly fast diffusion of the reaction products. In the desodiation, the dissociation of Na2O and formation of Co3O4 due to the de-conversion reaction are observed.
This work was supported as part of the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DEAC02-06CH11357, and the Initiative for Sustainability and Energy at Northwestern (ISEN). This work was also supported by the NUANCE Center, and made use of the EPIC facility (NUANCE Center-Northwestern University), which has received support from the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); and the State of Illinois, through the IIN. The nanocomposite sample is prepared with great help of Prof. Junming Xu at Hangzhou Dianzi University.
1. Yabuuchi, N.; Kubota, K.; Dahbi, M.; Komaba, S. Chem. Rev. 2014, 114, (23), 11636-11682.
2. Palomares, V.; Casas-Cabanas, M.; Castillo-Martínez, E.; Han, M. H.; Rojo, T. Energy Environ. Sci. 2013.
9:00 PM - EE4.6.06
A Study of Tin Dioxide-Graphene Oxide Composite for Supercapacitor Applications
Frank Mendoza 2,Valerio Dorvilien 2,Laura Mendez 4,Samuel Escobar 2,Brad Weiner 2,Gerardo Morell 2
1 University of Puerto Rico - Rio Piedras San Juan United States,2 Institute for Functional Nanomaterials San Juan United States,3 University of Puerto Rico San Juan United States,4 Medica Sciences University of Puerto Rico San Juan United States
Show AbstractWe propose a method to fabricate supercapacitors using tin dioxide-graphene oxide (SnO2-GO) composite. The GO composite expand the surface-to-volume ratio interaction of SnO2 nanoparticles demonstrating a desirable capacitance performance conforming an ideal material for supercapacitors applications. We explored a non-conventional process to synthesize SnO2-GO composite powder which is conformal structure was characterized under different techniques. Comprehensive analysis of the structural and chemical properties reveals that the material consists of highly dispersed SnO2 nanoparticles in GO matrix.
The dispersed SnO2-GO suspension was dropped and dried onto the shallow surface of paper conforming a conductive paper like electrodes. We examine the electrical conductivity of the conductive paper by four probes, atomic force microscope (AFM), scanning electron microscope (SEM) and transmission electron microscope (TEM). We assembled the paper-electrodes as a supercapacitor inserting one solid-state electrolyte between two electrodes, assembled into a sandwich structure. The specific capacitance and cycle-life stability of the paper-based supercapacitor was investigated by cyclic voltammetry analysis.
9:00 PM - EE4.6.07
Effect of CeO2 Nanoparticles Modification on Porous Carbon for High-Capacity Super-Capacitor Application
Mohammad Shuvo 1,Hasanul Karim 1,Md Islam 1,Gerardo Rodriguez 1,Ricardo Martinez 1,Ivan Gastelum 1,Manjula Nandasiri 2,Ashleigh Schwarz 2,Arun Devaraj 2,Juan Noveron 1,Murugesan Vijayakumar 2,Yirong Lin 1,Hoejiun Kim 1
1 University of Texas at El Paso El Paso United States,2 Pacific Northwest National Lab Richland United States
Show AbstractThe increasing demand for energy storage devices has propelled research for developing efficient super-capacitors (SC) with long cycle life and ultrahigh energy density. Carbon-based materials are commonly used as electrode materials for SC. Herein, we report a new approach to improve the SC performance utilizing a Porous Carbon /Cerium Oxide nanoparticle (PC-CON) hybrid as electrode material synthesized via a low temperature hydrothermal method.1M Tetraethyl Ammonium Tetrafluroboratein Acetonitrile was used as organic electrolyte. Through this approach, charges can be stored not only via electrochemical double layer capacitance (EDLC) from PC but also through pseudo-capacitive effect from CeO2 nanoparticles (NPs). The electrode-electrolyte interaction due to the electrochemical properties of the electrolyte provides a better voltage window for the SC. Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD) measurements were used for the initial characterization of this PC/CeO2 NPs hybrid material system. Electrochemical measurements of SCs were performed using potentio-galvanostat and LCR meter. The testing results have shown that a maximum 500% higher specific capacitance could be obtained using PC/CeO2 instead of PC only.
9:00 PM - EE4.6.08
Neutron Scattering Studies of Lithium-Ion Diffusion in Ternary Phosphate Glasses
Gavin Hester 1,Tom Heitmann 2,Madhusudan Tyagi 3,Munesh Rathore 4,Anshuman Dalvi 4,Saibal Mitra 1,Souleymane Diallo 5,Eugene Mamontov 5
1 Physics, Astronomy, and Materials Science Missouri State University Springfield United States,2 Materials Science University of Missouri Research Reactor Columbia United States3 National Center for Neutron Research National Institute of Standards and Technology Gaithersburg United States4 Birla Institute of Science and Technology Pilani India5 Chemical and Engineering Materials Division Oak Ridge National Laboratory Oak Ridge United States
Show AbstractIn order to fully exploit the potential of clean energy technology, the development of efficient power production sources and safe energy storage methods are vital. Conventional energy storage systems like lithium ion (Li+) batteries utilize liquid electrolytes. These liquid electrolytes often fail under extreme conditions or when dendritic shorts develop under normal performance. Many of these issues can be mitigated with the use of a solid electrolyte, of which amorphous (glassy) materials are a good candidate as they offer good conduction of Li+ while minimizing electron conduction. The glasses studied utilize the base glass forming compound P2O5 modified with Li2O; Li2SO4 is then added in differing quantities to modify the structure and increase Li+ conduction. The conduction of Li+ was measured using quasielastic neutron scattering at both the High Flux Backscattering Spectrometer at the NIST-National Center for Neutron Research. Structural measurements were performed at the Triple-Axis Spectrometer at the University of Missouri Research Reactor. We find that an increase of Li2SO4 causes an increase in the full width-half max of the fit for the quasielastic data, which corresponds to an increase in Li+ conduction until an over-saturation point is reached (<60% Li2SO4). It is also found that the Li2SO4 edits the modified glass structure in such a way that it increases the ability of the ions to make more successive diffusion jumps without effecting the length of the jumps. Our analysis shows that this diffusion mechanism follows the vacancy mediated Chudley-Elliot model. A fundamental understanding of the diffusion mechanism for these glassy compounds can help lead to the discovery of a highly efficient solid electrolyte and improve the viability of clean energy technologies.
9:00 PM - EE4.6.09
Morphological Evolution of Multilayer Ni/NiO Thin-Film Anodes during Lithiation
Guennadi Evmenenko 1,Timothy Fister 2,D. Bruce Buchholz 1,Xiao Chen 1,Jennifer Esbenshade 3,Qianqian Li 4,Jinsong Wu 4,Vinayak Dravid 4,Paul Fenter 2,Michael Bedzyk 1
1 Department of Materials Science and Engineering Northwestern University Evanston United States,2 Chemical Science and Engineering Argonne National Laboratory Lemont United States3 Department of Chemistry University of Illinois at Urbana-Champaign Urbana United States4 EPIC, NUANCE Center Northwestern University Evanston United States
Show AbstractWe focus on in-operando structural evolution of model Li-ion battery anodes, which are comprised of multi-bilayer Ni/NiO films with active NiO layers sandwiched between buffer Ni layers. The films were deposited on sapphire via pulsed laser deposition (PLD). The morphological changes accompanying lithiation were tracked via in-situ and ex-situ X-ray reflectivity (XRR) and cross-sectional transmission electron microscopy in a series of films produced by systematically varying the thicknesses of active and buffer layers (2 nm to 20 nm) and the number of periodic bilayers (1 to 5). The key results of these combined studies are:
1. Complete lithiation of all the active NiO layers occurs only when the thickness of the buffer Ni layers is less than ~5 nm. The thicker Ni layers present a kinetic barrier for lithium ions diffusion inside the stack resulting in partial lithiation of the multilayer anodes - only the top NiO layer is lithiated.
2. For fully lithiated films, the active NiO layers expand to twice their size. The lithiation process of multilayer anodes start at the top layers and then progressing toward the bottom of the stack. The expansion is accompanied by lateral inhomogeneities at early time periods, which wear out over time leading to laterally uniform lithiated multilayer archtectures.
3. The lithiation process is accompanied by reduction of NiO to Ni. This reduced Ni is distributed uniformly inside the lithiated active layers and as 0.6-0.7 nm thin films on the pre-existing Ni layers.
In my presentation, I will discuss the mechanisms of the observed structural transformations. These are the first systematic studies of vertically digitized multilayer anodes that precisely determine the relationships between the morphological changes and the film architecture during lithiation.
This research was supported by the Center for Electrochemical Energy Science, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
9:00 PM - EE4.6.10
Fabrication of a Novel Nanostructured SnO2/LiCoO2 Lithium-Ion Cell
Mark Poyner 1,Indumini Jayasekara 1,Dale Teeters 1
1 University of Tulsa Tulsa United States,
Show AbstractIncorporating nanotechnology processes and techniques to Li ion batteries has helped to improve the cycling capabilities and overall performance of several lithium ion battery chemistries. Nanostructuring a lithium ion battery’s anode and cathode, allows for extremely high surface area electrodes to be produced and utilized in many of these battery systems. Using a nanoporous Anodized Aluminum Oxide (AAO) membrane with nanopores of 200nm in diameter as a template, high surface area nanostructured electrode materials can be synthesized and utilized in a lithium ion cell. Through the use of RF magnetron sputter coating, these nanoporous AAO templates can be sputter coated with a thin film of active anode or cathode materials. The anode and cathode material in this research are SnO2 and LiCoO2, respectively. Sputtering deposits a target material in a line of sight method. As a result, sputter coating will deposit the electrode materials on the surface of the nanoporous AAO substrate, effectively templating the AAO membrane while maintaining the nanoporous-like nature of the substrate. This deposition process coupled with a nanostructured template, can create extremely high surface area electrodes. The surface area generated from this fabrication process results in about six times more surface area than a traditional thin film with no nanostructuring. This increase in available surface area is attributed to the added lateral surface area of the cylindrical-like nature of the nanopores. This added surface area leads to more electrolyte-electrode contact, the ability to intercalate Li ions into and out of the material faster, store more capacity and ultimately make more capable batteries. Nanostructured SnO2 has been investigated as an alternative high capacity anode to replace the more commonly used carbon based anodes of current lithium ion batteries. Difficulty with drastic increase in particle size upon lithiation has limited SnO2 functionality in cell design. By nanostructuring the SnO2 anode, the vast increase in particle size can be managed unlike traditional thin-films. The pore space provides the volume needed for the SnO2 material to swell and contract, while limiting the chances of microstructural cracks and other complications. A novel nanostructured SnO2/LiCoO2 cell can be fabricated in a liquid electrolyte. The galvanostatic cell cycling performance will be discussed. Nanostructuring both electrode materials as well as the electrolyte can lead to a novel all-solid-state Li ion battery. Nanostructured SnO2 anode and LiCoO2 electrodes have been generated along with a polyethylene-oxide (PEO) based electrolyte nanoconfined in an AAO membrane, to generate a functioning nanostructured all-solid-state cell. The cell was investigated using AC impedance spectroscopy and galvanostatic cell cycling. The cycling results of both SnO2/LiCoO2 cell systems will be discussed.
9:00 PM - EE4.6.11
Pyrolyzed Cellulose Paper Based Sulfur Cathode for High-Performance and Cost-Effective Lithium-Sulfur Batteries
Shiqi Li 2,Guofeng Ren 1,Zhaoyang Fan 1
1 Department of Electrical and Computer Engineering Texas Tech University Lubbock United States,2 Department of Science and Technology Chongqing Public Security Bureau Chongqing China,1 Department of Electrical and Computer Engineering Texas Tech University Lubbock United States
Show AbstractTo develop high-performance lithium-sulfur (Li-S) batteries, a large number of delicate and complex nanostructures have been reported as a conductive skeleton for sulfur anchoring, to overcome the insulating issue of sulfur species and alleviate their dissolution tendency. Most of these nanostructures may perform well in a testing cell, but they are unfavorable for practical application considering their cost and challenge for scaling up. Accordingly, economical raw materials and facile processes for fabricating sulfur cathodes deserve to be further explored. Cellulose, widely existing in plants such as grasses, stalks, cottons and wood, is the most abundant polymer on earth. Cellulose fibers are expected to be an excellent precursor candidate for producing economical carbon structures for sulfur cathodes. Herein, we demonstrate that cellulose marcofiber paper is directly pyrolyzed into mesoporous carbon paper after proper activation in ammonia. Meanwhile, lithium polysulfides solution can be simply soaked into such a carbon paper to form uniformly loaded sulfur cathode, avoiding the commonly adopted thermal diffusion process. Such a cost-effective electrode, through a facile process, exhibits an impressive performance. Even with a high mass-loading, the assembled Li-S cell still exhibits high capacity (>1200 mAh/g), high cycling stability and high rate capability, indicating this simple cathode structure potentially can be developed for practical Li-S battery technology. We will report in detail the process to fabricate the sulfur cathode from cellulose paper, and its physical, chemical and electrochemical properties, particularly the Li-S cell performance.
9:00 PM - EE4.6.12
Synthesis and Li-Ion Transport Properties of Garnet-Type Li-Ion Conductor Li7-xLa3Zr2-xBixO12
Reinhard Wagner 1,Daniel Rettenwander 1,Gerold Tippelt 1,Guenther Redhammer 1,Walter Schmidt 2,Martin Wilkening 2,Georg Amthauer 1
1 Department of Materials Research and Physics University of Salzburg Salzburg Austria,2 Christian Doppler Laboratory for Lithium Batteries, Institute for Chemistry and Technology of Materials Graz University of Technology Graz Austria
Show AbstractLi-stuffed oxide garnets combine a high Li-ion conductivity with an excellent chemical and thermal stability and electrochemical inertness, in particular against Li metal. Thus, these materials are excellent candidates for solid electrolytes in Li-ion and Li-oxygen batteries.1,2 Within this group, Li7La3Zr2O12 (LLZO) garnet and its variants are among the most promising materials. Pure LLZO occurs in at least two structural modifications: (i) a low-temperature tetragonal phase (space group I41/acd) and (ii) a high-temperature cubic phase (space group Ia-3d). In terms of applications, the cubic phase is much more desirable as its ion conductivity is two orders of magnitude higher (10-4-10-3 S/cm) compared to the tetragonal polymorph (about 10-6 S/cm).3 The cubic phase is not stable at room temperature and has to be stabilized by doping of LLZO with aliovalent cations.2
The unit-cell parameter and the Li content influence Li-ion conductivity properties of Li-stuffed oxide garnets.4 To obtain a larger unit-cell parameter as well as a high Li content, we partially replaced Zr4+ with Bi5+; as the unit-cell parameter of Li5La3Bi2O12 is as large as 13.065 Å.5 Cubic LLZO was successfully stabilized by partial replacement of Zr4+ with Bi5+. A significant increase of the unit-cell parameter with increasing Bi5+ content was confirmed by X-ray powder diffraction. Bi5+ stabilized LLZO showed a unit-cell parameter of up to 13.07 Å, compared to a unit-cell parameter of 12.97 Å for LLZO doped with Ga3+, Fe3+ or Al3+.4,5 The reason for this different behavior might be related to the crystallographic position and crystal-chemical properties of the dopant cation. Long-range ion transport properties of Bi5+ stabilized LLZO as a function of the Bi5+ content and, therefore, the influence of the unit-cell parameter on ion dynamics will be investigated by electrochemical impedance spectroscopy as well as 7Li NMR measurements. Results about Li-ion dynamics and electrochemical properties of Bi5+ stabilized LLZO will be presented as well.
1 Cussen, E.J.; J. Mat. Chem. 2010, 20, 5167-5173.
2 Thangadurai, V.; et al.; Chem. Soc. Rev. 2014, 43(13), 4714-4727.
3 Buschmann, H.; et al.; Phys. Chem. Chem. Phys. 2011, 13, 19378-19392.
4 Zeier, W. G.; Dalton Trans., 2014, 43, 16133-16138
5 Murugan, R.; et al.; Mat. Sci. Eng. B 2007, 143, 14-20
9:00 PM - EE4.6.13
Crystal Structure of Garnet-Related Li-Ion Conductor Li7-3xGaxLa3Zr2O12: Fast Li-Ion Conduction Caused by a Different Cubic Modification
Reinhard Wagner 1,Guenther Redhammer 1,Daniel Rettenwander 1,Maria Maier 1,Walter Schmidt 2,Martin Wilkening 2,Anatoliy Senyshyn 3,Georg Amthauer 1
1 Department of Materials Research and Physics University of Salzburg Salzburg Austria,2 Christian Doppler Laboratory for Lithium Batteries, Institute for Chemistry and Technology of Materials Graz University of Technology Graz Austria3 Research Neutron Reactor ZWE FRM-II Munich University of Technology Garching Germany
Show AbstractSince the initial studies in 2007, Li7La3Zr2O12 (LLZO) garnet received much scientific attention as solid electrolyte for “Beyond Li-ion Battery” concepts such as Li-air or Li-S batteries. LLZO provides a high ionic conductivity σtotal ≈ 10-3-10-4 S cm–1 at room temperature (RT), cationic transference numbers approaching 1, superior chemical stability against high voltage cathodes, and electrochemical inertness in a wide potential window (up to 5V). In particular, its stability against Li-metal as well as its thermal and mechanical stability makes LLZO garnet exceptionally well suited to be used as an electrolyte for Li-metal based batteries.1, 2
Pure LLZO occurs in at least two different modifications, (i) a low-temperature tetragonal phase with space group (SG) I41/acd (no. 142) and (ii) a cubic high-temperature phase with SG Ia-3d (no. 230). In terms of ionic transport, the cubic phase is much more desirable as its Li-ion conductivity is two orders of magnitude higher (10-4 to 10-3 S cm-1) compared to the tetragonal form of LLZO.2
The cubic modification can be stabilized at RT by introducing aliovalent cations such as Al3+ and Ga3+ (Ga3+↔ 3 Li+).3, 4 Initial studies assumed a similar behavior of Ga3+ compared to Al3+.5 Despite numerous studies performed to unravel the influence and the differences of Al and Ga on long-range Li-ion transport properties of LLZO, no satisfying answers were found. The present study is aimed at shedding light on the underlying structure-property relationships.
Coarse-grained Ga-stabilized LLZO samples were investigated by single crystal X-ray diffraction (SC-XRD). Surprisingly, Rietveld refinement of SC-XRD data points to the acentric cubic SG I-43d (no. 220). Neutron powder diffraction measurements confirmed the results from SC-XRD. As SG I-43d shows a different Li-ion sublattice compared to SG Ia-3d, a different Li-ion diffusion mechanism might be assumed. Interestingly, compared to Al-stabilized LLZO (SG Ia-3d) 7Li NMR relaxometry experiments revealed an additional dynamic process for Ga-stabilized LLZO (SG I-43d).
1 Murugan, R.; et al.; Angew. Chem. 2007, 119, 7925–7928
2 Thangadurai, V.; et al.; Chem. Soc. Rev. 2014, 43(13), 4714-4727
3 Buschmann, H.; et al.; Phys. Chem. Chem. Phys. 2011, 13, 19378-19392
4 Rettenwander, D.; et al.; Inorg. Chem. 2014, 53, (12), 6264-6269
5 Rettenwander, D.; et al.; Chem. Mater. 2015, 27, 3135–3142
9:00 PM - EE4.6.14
Low-Cost Carbon Composite Anodes for Sodium-Ion Batteries
Yunchao Li 2,Kokouvi Akato 2,Alan Levine 3,Rich Lee 3,Amit Naskar 2,Sang Kim 5,Arumugam Manthiram 5,Jinshui Zhang 1,Sheng Dai 1,Mariappan Paranthaman 2
1 Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge United States,2 The Bredesen Center for Interdisciplinary Research and Graduate Education The University of Tennessee Knoxville United States,3 RJ Lee Group Monroeville United States4 Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge United States,2 The Bredesen Center for Interdisciplinary Research and Graduate Education The University of Tennessee Knoxville United States5 Texas Materials Institute The University of Texas at Austin Austin United States1 Chemical Sciences Division Oak Ridge National Laboratory Oak Ridge United States
Show AbstractWith the growth of sustainable energy generation, there is an increased demand for large-scale energy storage to secure the grid system. Sodium-ion battery (SIB) gradually attracts a lot of attentions because of its low production cost, relatively high energy density and storage efficiency compared with existing stationary energy storage systems. Hard carbon is regarded as a promising anode material for sodium-ion batteries. However, the high costs of the hard carbon hinders its application in the market. Here, we report a low-cost, scalable waste tire-derived carbon anode for sodium-ion batteries. Tire-derived carbons show good stability when electrochemically intercalated by sodium ions. The tire-derived carbons pyrolyzed at 1100°C, 1400°C and 1600°C show capacities of 179, 185 and 203 mAh g-1, respectively, after 100 cycles at a current density of 20 mA g-1. Samples show a trend that the portion of the low voltage plateau region increases as the temperature goes up. Such low voltage plateau will greatly enhance the energy density of the full cell. This study provides a new pathway for inexpensive, environmentally benign and value-added waste tire-derived products towards large-scale energy storage applications.
9:00 PM - EE4.6.15
Effect of Carbon Coating on NaMn0.33Ni0.33Co0.33O2 by Functionalized MWCNTs for Sodium-Ion Batteries
Vijay Shankar Rangasamy 1,Savitha Thayumanasundaram 1,Seo Jin Won 1,Jean-Pierre Locquet 1
1 KU Leuven Heverlee Belgium,
Show AbstractAmong the post-Li ion batteries, Na-ion batteries have been gaining more attention thanks to the natural abundance and relatively low cost of sodium resources. In these systems, the greatest technical hurdle to overcome is the lack of high-performance electrodes. In this work, cathode material based on layered structure NaMn0.33Ni0.33Co0.33O2, simply NMNC, is synthesized by sol-gel using metal nitrates (NMNC-N) and metal acetates (NMNC-A) as precursors. The effect of using two different precursors on the morphology of the particles and electrochemical performances of the cathode material are discussed. XRD patterns confirm the formation of a stable phase of the material at 900 °C and could be indexed with the general NaCoO2 structure. The sample prepared using metal acetates shows flaky platelet-like morphology while for nitrate based sample shows spherical morphology. Electrochemical performance of the cathode material is evaluated by fabricating CR2032 sodium half-cell with NMNC as cathode and 1 M NaClO4 in EC/DMC mixture as the electrolyte. The charge/discharge capacities of the NMNC-A sample in the first and tenth cycles are 116/97 mAhg-1 and 96/82 mAhg-1, respectively. The capacity of the NMNC-N sample is about 20% less than that of NMNC-A due to the difference in the morphology. The capacity of both the samples fades significantly on further cycling. The electrochemical performance of this material can be improved by carbon coating, especially with MWCNTs. The carbon coating with carbon nanotubes resulting in a nanoscale networking will provide the advantage of both good electronic conductivity and short sodium ion diffusion length. Thus composite cathode is prepared by mixing functionalized MWCNTs with NMNC–A sample in N-methyl pyrrolidone (NMP) solution to enhance homogeneous mixing. Electrochemical performance of the composite cathode in sodium half-cell will also be discussed.
9:00 PM - EE4.6.16
Highly Effective Water-Soluble Binder for Li-S Battery Inspired by Paper Wet-Strengthening Chemistry
Jaebeom Jeon 1,Yeon Sik Jung 1
1 Korea Advanced Institute of Science and Technology Daejeon Korea (the Republic of),
Show AbstractAs one of the most promising candidates for advanced energy storage systems beyond conventional lithium ion batteries, lithium-sulfur (Li-S) batteries have been actively studied because of their high theoretical energy density and inexpensive electrode materials. In particular, various active materials based on sulfur-carbon composites have been introduced to overcome the issues of Li-S batteries such as low conductivity and electrode degradation caused by generated polysulfide species during battery cycling. On the other hand, the binding properties of polymeric binders on the surface of electrode materials also significantly affect cell performances. Although many binders based on hydrogen bonding mechanism have been widely studied, they cannot be directly applied on Li-S batteries because of their totally different surface chemistry. In this respect, we herein introduce cross-linkable and water-soluble polymer glyoxalated polyacrylamide (GxPAAm) as an effective binder for Li-S batteries. Inspired from wet-strengthening agent used in paper industries, we show that cross-linked GxPAAm (c-GxPAAm) with superior mechanical properties can effectively suppress the change of electrode during electrochemical reaction of Li-S even under electrolyte-wetted condition. Using c-GxPAAm as a binder, the Li-S cell showed superior cyclability compare to bare polyacrylamide as well as other conventional binders such as polyvinylidene fluoride(PVdF), polyethylene oxide(PEO) and aqueous binders often used for Si anode. It is also notable that the discharge capacity above ~800 mAh/g was obtained even without using any complex treatments on active materials, which is highly advantageous for mass-scale production.
9:00 PM - EE4.6.17
A Microcontact Impedance Study on NASICON-Type Li1+xAlxTi2-x(PO4)3 (0 ≤ x ≤ 0.5) Single Crystals
Daniel Rettenwander 1,Andreas Welzl 2,Sylke Pristat 3,Frank Tietz 4,Stefanie Taibl 2,Guenther Redhammer 1,Juergen Fleig 2,Reinhard Wagner 1
1 Department of Material Science amp; Physics University of Salzburg Salzburg Austria,2 Institute for Chemical Technologies and Analytics Vienna University of Technology Vienna Austria3 Materials Synthesis and Processing (IEK-1) Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research Jülich Germany3 Materials Synthesis and Processing (IEK-1) Forschungszentrum Jülich GmbH, Institute of Energy and Climate Research Jülich Germany,4 Helmholtz-Institute Münster, c/o Forschungszentrum Jülich GmbH Jülich Germany
Show AbstractLi1+xAlxTi2-x(PO4)3 (LATP) with NASICON-type structure (Na Super-Ionic Conductor, with space group ) is a promising solid electrolyte with total Li+ ion conductivity of approximately 10-4 - 10-3 S cm–1.1 Due to the very high bulk Li+ conductivity in this class of materials the corresponding arc in the complex impedance plane response in the high MHz range and can be only resolved at very low temperatures.2,3 Determination of the Li+ bulk conductivity is strongly simplified when large sized single crystals are available; as for polycrystalline pellets macroscopic electrodes may be used in electrical measurements and electrical properties can be determined without being restricted by the need for a proper separation of partly large grain boundary resistances. For LATP, however, as for many other oxides, such large single crystals are not available. Here, a modification of conventional impedance spectroscopy comes into play: microelectrodes deposited on large grains of a polycrystalline sample still allow impedance measurements which are unaffected by the resistivity of grain boundaries.4-6 This is caused by the spatially very constricted current distribution between neighboring microelectrodes. However, so far this technique of local impedance measurements was rarely applied to determine Li+ bulk conductivities in small single crystals.
In this contribution, for the first time microcontact impedance spectroscopy was applied to small LATP single crystals to exactly determine the Li+ bulk conductivity at room temperature. The resulting Li+ conductivity is thus independent of microstructural effects (e.g., grain sizes, grain boundaries, and density/porosity). In addition, the single crystals were carefully characterized by single crystal X-ray diffraction (SCXRD) and this enables a precise analysis of the impact of Al3+ substitution (e.g., crystal structure, Li+ content) on transport properties and a better understanding of the structure–property relationship of Li+-based NASICON materials.
1. Aono, H., Sugimoto, E., Sadaoka, Y., Imanaka, N., Adachi, G. J. Electrochem. Soc., 1990, 137, 1023-1027.
2. S. Breuer, V. Epp, Q. Ma, F. Tietz and M. Wilkening, J. Mater. Chem. A, 2015, 3, 21343
3. Wang, S.; Ben, L.; Li, H.; Chen, L. Solid State Ionics, 2014, 268, 110-116.
4. J. Fleig, S. Rodewald and J. Maier, J. Appl. Phys., 2000, 87, 2372.
5. S. Rodewald, J. Fleig and J. Maier, J. Am. Ceram. Soc., 2001, 84, 521.
6. J. Fleig, S. Rodewald and J. Maier,, 2000,, 905.
9:00 PM - EE4.6.18
In Situ Transmission Electron Microscopy Observation of Conversion Reaction in SnO2 Nanoparticle Using Graphene Liquid Cell
Joon Ha Chang 2,Jun Young Cheong 2,Sung Joo Kim 2,Hyeon Kook Seo 2,Jong Min Yuk 2,Il-Doo Kim 2,Jeong Yong Lee 2
1 Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) Daejeon Korea (the Republic of),2 Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon Korea (the Republic of),2 Department of Materials Science and Engineering Korea Advanced Institute of Science and Technology (KAIST) Daejeon Korea (the Republic of)
Show AbstractIn recent years, as industry has developed, the consumption of energy has highly increased and the need of energy storage system has been in demand. Especially, lithium ion battery (LIB) is widely used for rechargeable battery for laptops, mobiles electronic vehicles. However, development in LIBs for larger capacity and faster charge-discharge rate, commercially used anode such as graphite (theoretical capacity: 372 mAh/g) is known to have much limitations. The possible solution for these are to replace the anode materials with larger capacity. Among those anode candidates, tin oxide (SnO2) has been studied by many researchers because of its large theoretical capacity (790 mAh/g), low cost, natural abundance, and safety.
When manufactured as anode in LIB, SnO2 undergoes irreversible reaction with large capacity loss in the very first cycle in following cycles (conversion reaction, 4Li+ + 4e- + SnO2 → 2Li2O + Sn) and reaction with volume expansion of 250% (alloying reaction, xLi+ + xe- + Sn → LixSn, 0≤x≤4.4) which causes pulverization. To design SnO2 anodes with less capacity fading, principle understanding of the reactions occurring in lithiation of SnO2 is necessary.
Although the existence in conversion reaction is widely known in lithiation of SnO2 and many other metal oxides, previous researches in real-time observation were focused only in phase transformation and volume expansion, which are results of alloying reaction. Herein, we report in-situ observation of conversion reaction in SnO2 nanoparticle in liquid electrolyte system. Unlike many previous works conducted with solid diffusion of Li ions, realistic system with liquid electrolyte fully immersing SnO2 nanoparticles were adopted using graphene liquid cell.
When SnO2 nanoparticles were irradiated by electron beam, conversion reaction between the nanoparticles and the electrolyte was observed. Following analysis with high resolution transmission electron microscopy (HRTEM) showed that part of SnO2 nanoparticles reacted with Li and formed amorphous Li2O matrix. Moreover, precipitated Sn nanoparticles with size of few nanometers coexisting with unreacted SnO2 nanoparticles within Li2O matrix was observed. This observation is able to suggest the very beginning mechanism of conversion reaction, which was overlooked by many previously reported reaction models. Such establishment of well-designed model constructed by mechanism explanation through real-time observation will contribute to fundamental comprehension of lithiation behavior of SnO2 anode and further application to advanced LIBs.
9:00 PM - EE4.6.19
Design and Synthesis of New Quinone-Based Organic Materials for Long-Life and High-Rate Lithium Batteries
Joungphil Lee 1,Moon Jeong Park 2
1 Chemistry POSTECH Pohang Korea (the Republic of),1 Chemistry POSTECH Pohang Korea (the Republic of),2 Advanced Materials Sciences POSTECH Pohang Korea (the Republic of)
Show AbstractThere are rising demands for developing high-energy lithium-ion batteries (LIBs) for more widespread uses in a diverse range of applications. This inevitably requires the development of new electrode materials with high capacity and good electrochemical stability. Especially, for cathode materials, lithium metal oxides (e.g. LiCoO2 or LiFePO4) are commonly used in commercial LIBs, however, they are facing with fundamental limitations because of their low capacity (<170 mAh g-1), high cost, and limited lithium diffusion kinetics. In light of this challenge, a variety of new cathode materials are being explored for past decades. This include organic compounds, which have shown unique features over conventional inorganic materials that characterized by high theoretical gravimetric capacities, low temperature synthetic procedures (therefore relatively low cost), and flexibility. Unfortunately, major drawbacks such as high solubility into liquid electrolytes, poor electrical conductivity, and slow redox kinetics have impeded the practical uses of organic compounds in LIBs. Herein, we report a facile synthesis of a new set of naphthoquinone (NQ)-based organic materials through simple organic substitution reactions. In particular, upon the substitution of 2- and 3- positions of NQ ring with amino groups, 2,3-diamino-1,4-naphthoquinone (DANQ), exceptionally low band gap of 2.74 eV and remarkably enhanced lithium diffusion rate were achieved, enabling the implementation of high rate performance (> 20 C) from lithium-organic batteries. Theoretical examination on electronic structures of DANQ using DFT calculations was in good agreement with our experimental results. The dissolution of active materials into electrolytes was resolved by the use of carboxylated cathode frameworks by inducing the formation of peptide bonds with amino groups. Our lithium-organic batteries demonstrate high discharge potential plateaus over 2.3 V with high initial capacity of 250 mAh g-1 and 99 % capacity retention after 500 cycles. Compared to the other quinone materials, our DANQ shows outstanding battery performance and it can be considered as a viable alternative to the more widely studied lithium metal oxides for future LIBs.
9:00 PM - EE4.6.20
Step Conformal Solid Electrolyte Deposited by ALD on Robust 3D Silicon Scaffold for on Chip Li-Ion Microbattery
Manon Letiche 4,Etienne Eustache 4,Jeremy Freixas 4,Laurence Morgenroth 2,Pascal Tilmant 2,Pascal Roussel 1,Thierry Brousse 4,Christophe Lethien 4
1 UCCS Lille France,2 IEMN Lille France,4 Réseau sur le Stockage Électrochimique de l'Énergie Amiens France,3 IMN Nantes France,2 IEMN Lille France,4 Réseau sur le Stockage Électrochimique de l'Énergie Amiens France2 IEMN Lille France1 UCCS Lille France3 IMN Nantes France,4 Réseau sur le Stockage Électrochimique de l'Énergie Amiens France2 IEMN Lille France,4 Réseau sur le Stockage Électrochimique de l'Énergie Amiens France
Show AbstractWithin the current technological context, the demand on miniaturized power sources is growing. Then, one trendy way to provide these power sources is the elaboration of 3D all solid state micro-systems at the wafer level such as microbatteries or microsupercapacitor. The main technological breakthrough is the conformal deposition of a solid-state and pinhole free electrolyte thin film on 3D structures and Atomic Layer Deposition (ALD) has been shown to be a powerful technique to reach that purpose. Highly conformal lithium phosphate thin films have been grown on 3D silicon substrates by ALD using lithium tert-butoxide and trimethylphosphate precursors at 300 °C. The influence of the ALD parameters on the growth rate per cycle, crystallinity and morphology is consistent with previous reports [1, 2]. The low temperature lithium phosphate form (β-Li
3PO
4) thin film (60 nm thick) exhibits the highest reported ionic conductivity (9.10
-7 S.cm
-1) for a film deposited by ALD and an electrochemical stability window from 0.5 V up to 4.5 V vs Li/Li
+ [2, 3]. The deposited Li
3PO
4 has been demonstrated as a perfectively pinhole free and step-conformal layer on very high aspect ratio and highly robust 3D silicon microstructure (etched depth > 60 µm) for the first time: an area enlargement factor (AEF) close to 60 has been obtained using micro-electronic facilities as described in our previous work [4]. To fulfill the requirement of solid electrolyte, planar and 3D titanium dioxide based thin film electrodes haves been coated with the Li
3PO
4 layer. In that way, the 3D stacking layers (TiO
2 / Li
3PO
4) act as a part of all solid state on chip 3D Li-ion microbattery fabricated on 3 inches silicon wafer. Dry etching and ALD technologies are currently used in the microelectronic industry and the fabrication process could be easily transferred to pilot line production. The areal capacity of a 3D electrode (AEF = 60 and TiO
2 thickness = 120 nm) is expected higher than 0.4 mAh.cm
-2 at C/20. This is, to the best of the author’s knowledge, the highest value reported for a TiO
2 negative electrode deposited on a 3D topology, two times higher than the performance reported in [4].
*Corresponding authors:
[email protected],
[email protected] and
[email protected][1] Hamalainen, J., et al. (2012),
Journal of The Electrochemical Society 159 (3): A259-A263.
[2] Biqiong Wang, J. L., et al (2014),
Nanotechnology 25: 504007.
[3] Xie, J., et al. (2014),
Journal of The Electrochemical Society 162 (3): A249-A254.
[4] Eustache, E., et al. (2014).
Advanced Energy Materials 4 (8): 1301612.
9:00 PM - EE4.6.21
Experimental Phase Studies in the La-X-Ni-O (X=Mg, Ca, Sr) System for Metal-Air Batteries
Gizem Soydan 1,Emin Kondakci 1,Nuri Solak 1
1 Metallurgical and Materials Engineering Istanbul Technical University Istanbul Turkey,
Show AbstractThe La2NiO4 ternary phase with a layered perovskite structure is known as highly active for the oxygen reduction reaction (OOR) and the oxygen evolution (OER) in metal-air batteries. Doped lanthanum nickelates have also been considered as a potential cathode material for intermediate temperature solid oxide fuel cell applications. In recent experimental works show that the performance of nickelate type cathode can be improved by alkaline earth metal oxide doping such as MgO, CaO and SrO. However, there is no detailed literature information on phase equilibria of the La2O3-XO-NiO (X=Mg, Ca, Sr) ternary oxide system. In order to build chemically stable battery and fuel cells, not only the thermodynamic stability of the electrolyte and electrodes themselves, but also the reactivity between component materials should be well established. The work aimed to investigate ternary phase equilibria in the La2O3-XO-NiO oxide system (X=Mg, Ca, Sr) in order to investigate thermodynamic stability of doped La2NiO4 ternary compound.
The experimental work has been designed based on the calculated phase diagrams (CALPHAD calculations). In the case SrO and CaO of extended solid solutions (La,X)2NiO4 was found and the homogeneity range was experimentally determined. Also chemical potential diagrams of the system simulating fabricating conditions of the electrodes were calculated.
9:00 PM - EE4.6.22
TiO2-Coated Mesoporous Carbon Cathode for Lithium-Sulfur Battery
Se Min Oh 1,Yun Seok Choi 1,Xing Jin 1,Ji Man Kim 1
1 Chemistry Sungkyunkwan University Suwon Korea (the Republic of),
Show AbstractLithium-sulfur battery has gained much interests as the next generation of energy storage device. Despite of its superiority like high energy density, it confronts insuperable obstacle, polysulfide dissolution. To overcome this problem, various kinds of materials such as polymer, graphene, metal oxide were suggested as a physical barrier to impede the dissolution of polysulfide. Herein, another efficacious physical barrier was built by coating TiO2 layer over ordered mesoporous carbon (OMC). TiO2 layer was successfully coated by sol-gel method on OMC, which is a host material for embedding sulfur. Thin layer for TiO2 was identified by scanning and transmission electron microscopy. Amorphous nature of TiO2 was verified by powder XRD and UV-reflectance. The material was investigated as cathode for lithium-sulfur battery. The electrode of TiO2 coated OMC showed higher discharge capacity and cycling stability compared to OMC electrode. This possibly arises from TiO2 layer which capture the polysulfide within barrier, facilitating the reduction of sulfur. Therefore, higher amount of sulfur was accessible in electrochemical reaction of lithium-sulfur battery.
9:00 PM - EE4.6.23
CNT Sponge-Based Sulfur Cathodes with GO-Enhanced Separator for Lithium-Sulfur Batteries
Keisuke Hori 1,Kei Hasegawa 1,Yuta Nishina 2,Suguru Noda 1
1 Department of Applied Chemistry Waseda University Tokyo Japan,2 Research Core for Interdisciplinary Sciences Okayama University Okayama Japan
Show AbstractLithium-sulfur battery is expected for the novel electrical storage due to its high theoretical capacity (1675 mAh/g) [1]. It shows capacity that is 10 times higher than those of commercialized batteries which use LiCoO
2. Sulfur possesses many benefits besides the high energy capacity, such as low-cost, low-toxicity and abundance on Earth. However, the battery has three problems: the low electric conductivity (5×10
−30 S/cm at 25°C), the volume changes (179%) during the cycles, and the diffusion of polysulfide (reaction intermediates) toward the anode. The travel of the polysulfide leads to low Coulombic efficiency and capacity fading induced by the aggregation of sulfur [2,3].
In this work, we propose a new strategy to overcome these issues using carbon nanotubes (CNTs) and graphene oxide (GO). CNTs have unique one-dimensional nanostructure, and simple dispersion-filtration transforms CNTs to self-supporting, flexible papers of networked CNTs with good electrical conductivity and large pore volume. Such CNT sponge will enable reversible volumetric change of and sufficient electric path to sulfur when used as three dimensional current collectors. GO is a monolayer to a few layers of oxidized graphene and easily pile up to form continuous films, which might prevent polysulfide diffusion when used as two dimensional separator.
Submillimeter-long few-wall CNTs produced by fluidized-bed chemical vapor deposition method [4] were dispersed with 0.5 wt% sodium dodecylbenzene sulphonate solution. Then,it was vacuum filtrated, and 30-μm-thick CNT paper with high surface area (0.3 m
2 surface for 1 cm
2 paper) was fabricated. CNT-S cathodes with 30−60 wt% sulfur content were prepared by the sublimation method. The electrochemical analysis was conducted with 1 M lithium bis(trifluoromethanesulfonyl)imide in 1,2-dimetethoxyethane and 1,3-dioxolane (v:v=1:1) as the electrolyte and the lithium metal foil as the anode. The cathodes showed a high initial discharge capacity of over 1100 mAh/g
sulfur (close to the theoretical value) at 0.3 C-rate, but were not effective in Coulombic efficiency. We, then, examined GO-enhanced separator to prevent polysulfide diffusion. GO synthesized by the modified Hummer’s method [5] was used in our research. By filtration, GO layers of 10−1000 nm in thickness were prepared on polypropylene separators. The separator with 100-nm-thick GO enhanced the Coulombic efficiency from 88.7% to 96.3% without any additives such as LiNO
3.
References:
[1] A. Manthiram, et al., ACS Acc. Chem. Res.
46, 1125 (2013).
[2] S.S. Zhang, J. Power Sources
231, 153 (2013).
[3] M.K. Song, et al., Nanoscale
5, 2186 (2013).
[4] Z. Chen, et al., Carbon
80, 339 (2014).
[5] S. Yamamoto, et al., Nanoscale
6, 6501 (2014).
Corresponding Author: S. Noda
Tel: +81-03-5286-2769, Fax: +81-03-5286-2769,
E-mail:
[email protected]Web: http://www.f.waseda.jp/noda/
9:00 PM - EE4.6.24
Preparation of Nanostructured Li7La3Zr2O12 Solid Electrolyte via Templating on Nanocellulose Fibrils and Size Dependency of Phase Transformation
Zachary Gordon 1,Ting Yang 1,Candace Chan 1
1 Arizona State University Tempe United States,
Show AbstractSolid electrolytes are a current research development aimed at reducing the flammability and reactivity of lithium-ion batteries. The garnet-type Li7La3Zr2O12 (LLZO) is of interest due to its satisfactory ionic conductivity in the cubic phase, which is several orders of magnitude higher than its conductivity in the tetragonal phase. However, LLZO normally requires the use of Al or other extrinsic dopants to stabilize the cubic phase. As an alternative to doping, it has recently been discovered that there is a direct relationship between phase stability and LLZO size, with nanostructured LLZO exhibiting cubic phase stability. Here nanostructured LLZO was formed via templating on various cellulosic fibers, including filter paper, lab tissue wipes, and nanocellulose fibrils. Templating was determined to be an effective method for controlling LLZO size and morphology, with most experiments resulting in fibrous LLZO of the same magnitude and morphology as the starting template. Furthermore, heating conditions that favored grain growth and larger LLZO fibers yielded tetragonal phase, while lower annealing temperature and slower heating rates produced thinner LLZO fibers stable in the cubic phase. Nanocellulose fibril templates, in particular, consistently generated cubic phase LLZO with calcination at 700-800 °C for 6-24 h without the use of dopants. The results indicate a strong correlation between cubic stabilization and fiber diameter, providing much information on a novel phenomenon not previously investigated in detail.
9:00 PM - EE4.6.25
Preparation of High Lithium Ion Conductive, Multi-Doped Li7La3Zr2O12 Solid Electrolyte
Dong Ok Shin 1,Kyungbae Oh 2,Kwang Man Kim 1,Kyu-Young Park 2,Byungju Lee 2,Young-Gi Lee 1,Kisuk Kang 2
1 Electronics and Telecommunications Research Institute (ETRI) Daejeon Korea (the Republic of),2 Seoul National University Seoul Korea (the Republic of)
Show AbstractWe investigate the doping effects on the lithium ionic transport behavior in cubic garnet Li7La3Zr2O12 (LLZO) experimentally and theoretically. The concentration of Li-ion vacancy generated by the inclusion of supervalent doping elements, plays a key role in stabilizing the cubic LLZO. Thus, more fast stabilization of cubic LLZO is observed for the Al and Ta double-doped LLZO compared to the single Al-doped LLZO. Moreover, in the single Al-doped LLZO, the site preference of Al substituting a 24d-positioned Li hinders the 3D-connected Li movement. Whereas, the additional Ta doping into the Al-doped LLZO moves the energetically favorable site occupancy of majority of Al from 24d to 96h, providing more open space for Li transport. Owing to these synergistic effects, the double-doped LLZO shows a total ionic conductivity of 6.14x10-4 S cm-1 and activation energy of 0.29 eV.
9:00 PM - EE4.6.27
Electrospinning of Nanostructured Li7La3Zr2O12 Solid Electrolytes and Its Particle Size-Dependent Phase Transformation
Ting Yang 1,Zachary Gordon 2,Ying Li 1,Candace Chan 1
1 Materials Science and Engineering Arizona State University Tempe United States,2 Chemical Engineering Arizona State University Tempe United States
Show AbstractLithium lanthanum zirconate (Li7La3Zr2O12, LLZO) is a promising ceramic solid electrolyte for all-solid-state lithium batteries with improved safety characteristics. However, the different phases of LLZO, namely tetragonal and cubic, differ in lithium ionic conductivity by several orders of magnitude, with extrinsic dopants often required to stabilize the high conductivity cubic phase. Here we show that cubic LLZO can be stabilized at room temperature in nanostructured particles without the use of extrinsic dopants. LLZO nanowires were synthesized using electrospinning and formed cubic phase materials after only 3 h calcination at 700 °C. Bulk LLZO with tetragonal structure was transformed to the cubic phase using particle size reduction via ball milling. Heating conditions that promoted particle coalescence and grain growth induced a transformation from the cubic to tetragonal phase in both types of nanostructured LLZO. Using nanostructured LLZO over bulk LLZO can be beneficial in terms of ionic conductivity, cycle life, and mechanical strength. Detailed structural characterizations with XRD and TEM were performed to understand the LLZO formation processes and phase transformations.
9:00 PM - EE4.6.28
Inexpensively Synthesized Tin and Antimony-Based Nanocrystals as Electrode Material for Lithium-Ion and Sodium-Ion Batteries
Marc Walter 2,Simon Doswald 2,Maksym Kovalenko 2
1 Laboratory of Inorganic Chemistry ETH Zurich Zurich Switzerland,2 Empa - Swiss Federal Laboratories for Materials Science and Technology Dübendorf Switzerland,
Show AbstractTo meet the demands for Lithium-ion batteries (LIBs) with higher energy and power density for applications such as electric cars or stationary energy storage the development of novel electrode materials is crucial. This is even more important for sodium-ion batteries (SIBs) – a potentially more economical alternative to LIBs – because graphite, the commercialized anode material for lithium, shows only a negligible capacity for sodium-ion storage. Both as potential anodes for LIBs and SIBs, alloying-type materials such as Sb or Sn are very promising due to their high specific and volumetric capacities (e.g. 992 mAhg-1 for Li4.4Sn corresponding to ~7300 mAhcm-3). However, upon alloying with lithium or sodium these materials undergo massive volume changes of 300–130%, which lead to continuous mechanical deterioration of the electrodes during cycling and therefore fast capacity fading. To alleviate the impact of these volume changes on the cycling stability and in addition enhance the reaction kinetics, nanostructuring of the electrode material has been demonstrated an effective method, which however is typically associated with expensive synthetic techniques. We report simple and inexpensive synthetic procedures to prepare nanocrystals of Sb and Sn as well as the nanoalloys SnSb and CoSnx and demonstrate their Li- and Na-ion storage properties both in half- and full-cells.1,2 In particular, SnSb nanocrystals as anode material for LIBs deliver capacities of ~890 mAh g-1 for 100 cycles at a current rate of 200 mAg-1 and show excellent rate capability retaining ≥80% of the theoretical capacity at a rate of 5000 mAg-1. In addition, amorphous CoSnx NPs show ultrahigh cycling stability retaining 92% (525 mAhg-1) of their capacity after 1500 cycles at a current of 1982 mAg-1.
[1] M. Walter, R. Erni and M. V. Kovalenko Scientific Reports, 2015, 5, 8418.
[2] M. Walter, S. Doswald and M. V. Kovalenko, submitted.
9:00 PM - EE4.6.29
High Capacity, Safe and Stable Anode/Electrolyte for Lithium-Ion Batteries
Yuzi Zhang 1,Yanjing Chen 1,Brett Lucht 1,Arijit Bose 1
1 Univ of Rhode Island Kingston United States,
Show AbstractWe use simple colloidal processing principles to organize silicon nanoparticles (SI NP) and graphene nanoplatelets (GNP) in a solid polymer (PEO) electrolyte. This anode/electrolyte combination is stable, safe, has high specific capacity and maintains a high Coulombic efficiency over 50 cycles. The rate performance is also excellent. We attribute this superior performance to the homogeneous distribution of SiNP and GNP in the polymer; the SiNP is not only the active material in the anode, but it also acts to prevent restacking of GNP, thus providing high electrical conductivity at carbon loadings that are far lower than that required conductive carbon black.
Symposium Organizers
Mariappan Parans Paranthaman, Oak Ridge National Laboratory
Ayyakkannu Manivannan, USDOE/NETL
Yang-Kook Sun, Hanyang University
Donghai Wang, The Pennsylvania State University
Symposium Support
Aldrich Materials Science
EE4.7: Sodium-Ion Batteries
Session Chairs
Thursday AM, March 31, 2016
PCC North, 100 Level, Room 124 A
9:30 AM - *EE4.7.01
In Situ Characterization of Advanced Electrode Materials for Na-Ion Batteries by Using Synchrotron Based Techniques
Xiao-Qing Yang 1,Xiqian Yu 1,Seogmin Bak 1,Enyuan Hu 1,Jue Liu 1,Hungsui Lee 1
1 Brookhaven National Lab Upton United States,
Show AbstractThe concerns of global climate change and environmental issues have promoted intensive research on energy storage technologies and their applications on electric vehicles and smart grid, aiming to the utilization of renewable energy sources such as wind and solar. The rechargeable battery is one of the most important fields for electric energy storage. Although lithium-ion batteries have been widely used in portable electronic devices and are considered to be the best choice for electric vehicles, the increasing cost and limited resources of lithium may restrict their applications, especially in large-scale energy storage systems. In this sense, sodium ion batteries demonstrate their advantages due to the abundance of sodium resources and potential low cost as well as the similarity of sodium-ion chemistry to that of lithium-ion, therefore sodium ion batteries have attracted a great deal of interests in both scientific and technological aspects. Plenty of new cathode and anode materials have been discovered recently. However, their sodium storage mechanisms are not quite clearly understood yet. A combination of the in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) can provide a powerful tool to study various aspects of the crystal structural and electronic structure changes associated with Na+ insertion and extraction during discharge and charge process. In this talk, several case studies on various electrode materials including transition metal oxide cathode and carbide anode for Na-ion battery application will be discussed. These results will provide valuable guidance for developing new electrode materials with improved battery performances, in terms of cycle stability, rate capability and safety characteristic.
ACKNOWLEDGMENT
The work done at Brookhaven National Lab. was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. DOE under Contract No. DE-SC-0012704.
10:00 AM - EE4.7.02
Structure Property Relationships of Na-Ions in an Amorphous Carbon Structure
Clement Bommier 1,P. Alex Greaney 2,Xiulei Ji 1
1 Department of Chemistry Oregon State University Corvallis United States,2 Department of Mechanical Engineering University of California Riverside Riverside United States
Show AbstractAmorphous carbon has played a key part in the development of Na-ion battery (NIB) anode materials—and its importance will only grow as NIB technology continues to mature. Though there are many other candidate anode materials, few can match the combination of performance, safety and low-cost which amorphous carbon can provide. For this reason, it is of the utmost importance that we develop a sound fundamental understanding of the nanoscale interactions between Na-ions and its amorphous carbon host structure--as such insights will be necessary to optimize material design and subsequently battery performance. Herein, we present the results of an in-depth study, which reveals some new mechanistic insights on the storage of Na-ions in an amorphous carbon structure. This task was achieved through advanced characterization using PDF measurements obtained via neutron scattering, insitu diffusivity measurements as well as more traditional methods. Additionally, we further explored these structure property relationships through both density functional theory (DFT) and molecular dynamics (MD) modeling. The use of these two techniques allowed us to simulate both the interaction between Na atoms representative carbon structures. The MD models made it possible to simulate a theoretical amorphous carbon structure with which we can compare experimental PDF results. Through our results, we are able to show that the storage mechanism can be divided into a three-tiered process involving storage at defect sites, intercalation and surface deposition. Furthermore, our theoretical simulations have enabled us to reveal a wealth of new information concerning the surface morphology of amorphous carbon as well as Na-carbon interactions at the nanoscale.
10:15 AM - EE4.7.03
High Rate Performance of Bamboo-Like LiFePO4 Nanotubes
M. Viji 1,Pravati Swain 1,Pavana S.V. Mocherla 1,Sudakar Chandran 1
1 Multifunctional Materials Laboratory Indian Institute of Technology Madras Chennai India,
Show AbstractLithium iron phosphate (LFP) bamboo-like nanotubes are fabricated directly on Al current collectors by template assisted sol-gel method. LiFePO4 nanotubes (LFP-NT) exhibit high specific capacity (~165 mAh/g at 1 C-rate) and superior high-rate capability with reversible capacity of ~100 mAh/g (~ 60 mAh/g) at a current rate of 10 C (25 C) with almost 100 % capacity retention after 1000 cycles. The electrochemical performance of LFP-NT are compared with LiFePO4 nanoparticles (LFP-NP) prepared by the same sol-gel method. LFP-NP samples showed significant drop in capacity, 65mAh/g and <10 mAh/g at 2C and 5C rate respectively, with largely sloping potential decrease. LFP-NW samples show large capacity (~125 mAh/g) at these C-rates. Interestingly a capacity of 25 mAh/g, even at 50 C-rate, was exhibited by LFP-NW cathode showing the high rate capability charging-discharging cycles. LFP-NP exhibit poor capacity retention even at low C-rates (< 10 mAh/g at 5C-rate). While both the microstructures have shortened pathways for Li ion transport, LFP-NT exhibit superior electrochemical performance due to its curved cylindrical structure which has large number of the entry points of 1D channels running along b-axis of olivine structure compared to agglomerates of LFP-NP. Fabricating LFP nanostructures with Li-ion accessability to 1D-channel entry points on the surface of LFP is crucial for achieving high-rate capability cathode.
10:30 AM - EE4.7.04
Exploring High-Performance Electrodes for Lithium-Ion and Lithium-O2 Batteries Based on Aligned Carbon Nanotube Frameworks
Yang Wu 2,Yang Wei 2,Jiaping Wang 2,Kaili Jiang 2,Shoushan Fan 2,Shunchao Ma 3,Zhangquan Peng 3
2 Department of Physics and Tsinghua-Foxconn Nanotechnology Research Center Tsinghua University Beijing China,3 State Key Laboratory of Electroanalytical Chemistry ChangChun Institute of Applied Chemistry, CAS Changchun China
Show AbstractThere has been a great challenge in developing new type electrodes for Li-ion and Li-O2 batteries to fulfill the urgent demand in high capacity and excellent reversibility of the next-generation energy storage devices. The attempts in seeking high capacity electrodes guided our first interest to the nano-sized oxides of transition metals, such as Fe, Co and Mn. Such metal oxides exhibited high theoretical capacities around 1000 mAh/g, but at the expense of problematic volume expansion and low electric conductivities. To address these issues, we synthesized nano-sized metal oxide particles on the surface of aligned carbon nanotube (CNT) yarns to form a sheath-core composite. The synthesis was carried out by integrating the CNT film drawing from CNT arrays and magnetron sputtering in a lab-designed apparatus. The electrochemical characterizations reveal that the CNT framework guarantees the high capacities by buffering the the volume expansion of metal oxides and effectively transferring the electrons. Furthermore, the sputtering process is versatile to realize other sheath-core nano structures such as the porous O2 cathodes for aprotic Li-O2 batteries. The noble catalyst, Ru and Pd, which were assumed to reduce the kinetic barriers of both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) was fabricated on the CNT framework. By quantitatively analyzing gaseous products with differential electrochemical mass spectroscopy (DEMS), we found that even though nano-sized Ru and Pd catalyzed Li-O2 electrochemistry, the by-product CO2 was released at a considerable amount during charing. The reversibility was actually impaired, as evidenced by the decreased O2 recovery efficiency coupled with increased CO2 evolution. Thus, the CNT framework can be regarded as a play stage to uncover the functionality of a variety of electrodes for both Li-ion and Li-O2 batteries. Finally, the utilization of flexible and mechanically robust CNT framework to fabricate thin film Li-ion batteries will be discussed.
[1] Wu, Y.; Wei, Y.; Wang, J.P. et al, Nano. Lett. 13 (2013) 818-823
[2] Ma, S. C.; Wu, Y.; Wang, J. W.; et al. Nano Lett. in revision
[3] Wu, Y.; Wang, J. P.; Jiang, K. L.; Fan, S.S. Front. Phys., (2014), 9, 351
[4] Wu, Y.; Wu, H. C.; Luo, S. et al. RSC Advances (2014), 4, 20010
10:45 AM - EE4.7.05
3D Morphological Evolution of Nanoporous Silicon Anode in Lithium Ion Battery by X-Ray Nano-Tomography
Chonghang Zhao 1,Takeshi Wada 2,Vincent De Andrade 3,Doga Gursoy 3,Juergen Thieme 4,Hidemi Kato 2,Yu-chen Karen Chen-Wiegart 4
1 Materials Science and Engineering Stony Brook University Stony Brook United States,2 Institute for Materials Research Tohoku University Katahira Japan3 Advanced Photon Source Argonne National Laboratory Argonne United States4 National Synchrotron Light Source II Brookhaven National Laboratory Upton United States
Show AbstractSilicon with its more than 10 times theoretical Li capacity than graphite, becomes one of the most proposing alternative anode materials in lithium-ion batteries. However, its application is challenging by more than 400% volume expansion during lithiation, and the subsequent volume reduction during de-lithiation. To solve this issue, Si nanowires, nanotubes and nano porous structure were fabricated, which can reduce mechanism stress during lithiation and also having large surface area for rapid charging. Despite of high reversible capacity, most of fabrication methods for Si nanostructure remain complex and expensive.
Here we investigate a novel form of nano-porous Si structure prepared by simple de-alloying method. The nanopores effectively prevent electrode cracking and therefore ensure long term durability and stable performance within batteries. However, morphology changes and degradation of the Si nanoporous electrode during charging and discharging are still not fully understood, which limit utilizing this novel electrode with its full capacity. We apply synchrotron based x-ray nano-tomography to directly observe the anode morphology changes under different cycling conditions, including cycling times, current rate and charge capacity. 3D morphological changes were observed and and correlated with operation conditions and performances of the batteries. The understanding between the morphological evolution and the degradation of the batteries will be discussed.
11:30 AM - *EE4.7.06
Roles of Solid Electrolyte Interphases in Lithium - Sulfur and Lithium - Metal Fluoride Batteries
Gleb Yushin 1
1 Georgia Inst of Tech Atlanta United States,
Show AbstractConversion-type high capacity cathode materials offer promisses for higher specific energy and reduced costs to rechargeable Li metal and Li-ion batteries. This talk will first discuss cost, volumetric and specific capacities, energy densities, volume changes and rate performance of group 6 and group 7 - based materials, such as sulphur (S) & lithium sulphide (Li2S), selenium (Se) & lithium selenide (Li2Se), tellurium (Te) & lithium telluride (Li2Te), metal fluorides, metal chlorides, metal bromides and metal iodides. Issues, such as volume changes, cathode dissolution, low electronic and ionic conductivities, voltage hysteresis, self-discharge and irreversible structural changes as well as possible routes to mitigate those issues will be discussed. Emphasis will be given to Li-S/Li2S as well as Li-metal fluoride chemistries. The impacts of the solid electrolyte interphase (SEI) layers (forming on the anode and the cathode) on the stability and rate performance of these cells will be elucidated. Challenges in the implementation of these chemistries will be compared with the potential of some of the chemistries to increase the energy density and specific energy of Li and Li-ion batteries.
Acknowledgements
Selected aspects of this work were supported by US Army Research Office (ARO), QNRF (project NPRP 7 - 567 - 2 – 216), US National Aeronautics and Space Administration (NASA) and US Air Force Office of Scientific Research (AFOSR)
12:00 PM - EE4.7.07
SiC-Free Graphene Growth and Inter-Layer Sliding for Silicon Anodes with High Volumetric Energy Densities
In Hyuk Son 1,Jong Hwan Park 1,Jang Wook Choi 2,Jae-man Choi 1,Seok Gwang Doo 1
1 Samsung Advanced Institute of Technology Suwon-si Korea (the Republic of),2 Korea Advanced Institute of Science and Technology (KAIST) Daejeon Korea (the Republic of)
Show AbstractThe unprecedented gravimetric capacity of Si near 4000 mAh g-1 has stimulated the battery community to intensively investigate Si anodes. As a result, inherently weak cycling performance originating from large volume change of Si during repeated charge-discharge cycles was improved significantly. Nonetheless, the Si anode technology has a substantial gap before its commercialization for the case where Si serves as a major active component, not a supplementary component to graphite. The main bottleneck in commercializing Si anodes is their uncompetitive volumetric energy density and insufficient cycle lives. The weakness in the volumetric energy density is related to the limited electrode design that the volume expansion of Si is accommodated via pre-defined void space. In this regard, the high gravimetric energy density, the common selling point prevailing in the academic community, needs to be reconsidered and reset with respect to the volumetric standards.
The present work overcomes this longstanding challenge in terms of the volumetric energy density and cycle life by developing a gas-phase graphene growth process on Si without SiC formation. SiC-free graphene growth on Si surface has been nontrivial at all because typical reductive environments essential for graphene growth strips the native oxide layer from Si surface and drives SiC formation. We, however, avoid this drawback for the first time by adding a mild oxidant, CO2, in the growth process [1]. Remarkably, SiC-free graphene coating can accommodate the volume expansion of Si via “sliding process” without the necessity of pre-defined void space. The sliding process allows us to increase the volumetric energy density significantly while exhibiting robust cycling performance. The volumetric energy density when constituted into a full-cell by pairing with a commercial cathode (LiCoO2) reaches 972 Wh L-1, which is ~1.8 times higher than those (~550 Wh L-1) of current commercial LIBs based on graphite anodes. This increased volumetric energy density was indeed validated when the cell electrodes were wound into a commercial 18650 cylindrical cell case. In addition, even 1 wt% addition of graphene increases the film conductivity to 12.8 cm S-1 through an efficient percolation network, which is ~108 times higher than that of bare Si without a graphene coating [2]. Moreover, from the processing viewpoint, graphene growth is very uniform around each particle as well as over multiple particles so we judge it highly scalable. We believe that the present work provides strong evidence of the feasibility of Si anodes for their commercialization and will serve as a landmark in the Si anode research.
References
[1] Son, I. H. et. Al. CO2 Enhanced Chemical Vapor Deposition Growth of Few-Layer Graphene over NiOx ACS Nano, 2014, 8, 9224.
[2] Son, I. H. et. Al. Silicon carbide-free graphene growth on silicon for lithium-ion battery with high volumetric energy density. Nat. Commun. 2015, 6, 7393.
12:15 PM - EE4.7.08
In Situ Monitoring of Elastic Properties of Common Binders via Electrochemical Quartz Microbalance with Dissipation and Dilatometry
Nicolas Jaeckel 2,Mikhael D. Levi 3,Doron Aurbach 3,Volker Presser 2
1 INM- Leibniz Institute for New Materials Saarbrücken Germany,2 Department of Materials Science and Engineering Saarland University Saarbrücken Germany,3 Department of Chemistry Bar-Ilan University Ramat-Gan Israel
Show AbstractThe cycling performance of composite lithium ion batteries and hybrid supercapacitor electrodes is strongly influenced by significant dimensional changes (deformation) of the active electrode material while the reversible lithium ion intercalation and deintercalation.[1] Typical composite cathodes are composed of an active material (i.e., lithium iron phosphate) with conductive additives and a polymeric binder.[2,3] Dimensional changes apply stress not only on the active material, but also on the binder. The viscoelastic properties of the different binders in a certain electrolyte influence the swelling and shrinkage.[4] We present a new complementary approach of a non-invasive in-situ monitoring of the dimensional changes via electrical quartz crystal microbalance with dissipation monitoring (EQCM-D) and electrochemical dilatometry.[5] This approach combines in situ probing of single-particle effects measured with EQCM-D and bulk in operando testing on composite electrodes via electrical dilatometry measurements over several orders of magnitude.
The monitoring of elastic properties of three different polymeric binders was carried out in an aqueous electrolyte (0.1 M LiSO4). While monitoring EQCM-D using a hydrodynamic admittance model, signals we can see change in frequency and dissipation by cycling voltammetry which are related to single particle effects. Measuring the same system in dilatometry cells we can see an average effect of the whole bulk electrode, which results in dimensional changes less for rigid binder types and much larger for soft ones. We find the combination of both, EQCM-D and dilatometry, as a unique tool to track the structural behavior of the binder in-situ and non-invasive during intercalation and deintercalation of Li ions into lithium iron phosphate composite electrode.
1. Shpigel, N., et al., Non-Invasive In Situ Dynamic Monitoring of Elastic Properties of Composite Battery Electrodes by EQCM-D. Angew. Chem. Int. Ed., 2015. 54(42): p. 12353-12356.
2. Miller, J.R., Valuing Reversible Energy Storage. Science, 2012. 335(6074): p. 1312-1313.
3. Aurbach, D., et al., Design of electrolyte solutions for Li and Li-ion batteries: a review. Electrochim. Acta, 2004. 50(2-3): p. 247-254.
4. Daikhin, L., et al., Quartz crystal impedance response of nonhomogenous composite electrodes in contact with liquids. Anal. Chem., 2011. 83(24): p. 9614-21.
5. Levi, M.D., et al., In Situ Tracking of Ion Insertion in Iron Phosphate Olivine Electrodes via Electrochemical Quartz Crystal Admittance. J. Phys. Chem. C, 2013. 117(3): p. 1247-1256.
12:30 PM - EE4.7.09
In Situ Characterization of Stress Evolution and Volume Expansion Associated with Cycling of Prismatic Lithium-Ion Batteries
Jianlin Li 1,Yanli Wang 2,Congrui Jin 3,Claus Daniel 1,David Wood 1
1 Oak Ridge National Laboratory Oak Ridge United States,2 Materials Science and Technology Division Oak Ridge National Laboratory Oak Ridge United States3 Department of Mechanical Engineering State University of New York at Binghamton Binghamton United States
Show AbstractGreat efforts have been made in characterizing lattice charge of active materials during cycling, which provides insight into the electrode expansion/contraction and overall volume change of batteries. However, it can’t take into account of other factors, such as solid electrolyte interface (SEI) formation, interaction between binder and active material, which also contributes to the overall volume change of batteries during cycling. This talk presents a straight forward technique to measure the volume and stress changes in prismatic lithium-ion batteries with LiNi0.5Mn0.3Co0.2O2 and graphite electrodes. The correlation between stress evolution/volume change and initial battery compression, cutoff voltage window and current density is systematically investigated. The results provide insight on the overall dimensional change of batteries, which is beneficial for battery pack design to compromise battery performance, energy density and safety.
Acknowledgement:
This research at Oak Ridge National Laboratory (ORNL), managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) under contract DE-AC05-00OR22725, was sponsored by the U.S.-China Clean Energy Research Center-Clean Vehicles Consortium. The prismatic cells were fabricated at the Battery Manufacturing Facility at ORNL, which was funded by Office of Energy Efficiency and Renewable Energy for the Vehicle Technologies Office's (VTO) Applied Battery Research Program (Program Managers: Peter Faguy and David Howell).
12:45 PM - EE4.7.10
Hierarchical Architecture of Ultrafine TiO2 Nanocrystals Integrated with the Binder-Free Macroporous Graphene for Energy Storage Enabling Ultrafast Rate Capability and Robust Cycle Life
Gyu Heon Lee 1,Jung Woo Lee 1,Jeung Ku Kang 1
1 Material Science and Engineering Korea Advanced Institute of Technology Daejeon Korea (the Republic of),
Show AbstractLithium ion battery systems are the indispensable technology in portable electronic devices and electrical vehicles. Titanium (IV) oxide is one of the promising material for electrochemical applications. It is earth abundant, low cost, eco-friendly, high safety and high chemical stability. TiO2 has also fast lithium ion insertion characteristic without its structural changes which is important in the performance of lithium ion batteries. Although it suffers from low electro-conductivity resulting in low capacitance at high current rates, it was demonstrated this weakness could be improved through nanostructuring TiO2 and additional conducting materials such as graphitic carbon.
In this research, we demonstrate a hierachical architecture fabricated by integrating ultrafine (~ 6 nm) TiO2 nanoparticles (NPs) with the binder-free macroporous (~ 50 µm) graphene network for the extremely high rate capability and stable cycling performances of Li-ion battery anode. It was found that the mesoporous open channels between TiO2 NPs and the macroporous graphene facilitate fast ionic transfer during lithiation/delithiation. Moreover, the binder-free conductive graphene network in direct contact with the current collector is found to provide ultra-low sheet resistance (~ 4.53 Ω sq-1) , thus giving ultra-fast electronic transfer as well. Consequently, this hierarchical structure results in unprecedented cycling performance such that a substantial portion of initial capacity is preserved with almost the 100% Coulombic efficiency over 10,000 cycles of Li-ion insertion/desertion and ultra-fast charge/discharge behaviors even at an extremely high current of 30,000 mA g-1, thus providing power performance entangled with high capacity for the lithium ion battery being fully chargeable in a very short time.
EE4.8: Nanostructured Electrodes, Theory and Simulations
Session Chairs
Thursday PM, March 31, 2016
PCC North, 100 Level, Room 124 A
2:30 PM - EE4.8.01
Mineral-Inspired, Nanostructured Polyanion Materials for Rechargeable Battery Electrode
Ran Zhao 1,Ting Yang 1,Candace Chan 1
1 Arizona State University Tempe United States,
Show AbstractPolyanion materials are promising candidates for new rechargeable battery electrodes due to their good capacity, operation voltage, safety characteristics, as well as low cost. A family of materials based on metal hydroxysulfate or hydroxyphosphate naturally occurring minerals offers the possibility for improved performance as cathode materials due to the following characteristics: (1) open framework or layered structures that can facilitate fast Li+ insertion, (2) flexibility in alkali and transition metal cation incorporation as observed in nature, which can allow for the design of solid-solutions to enhance structural stability, capacity, and reaction potentials, and (3) possibility for multi-electron redox reactions, which can result in capacities >200 mAh/g. This presentation will introduce our investigation into nanostructured brochantite and mircrotructured jarosite minerals for use as electrodes in Li-ion and Na-ion batteries.
The electrochemical properties of brochantite, Cu4(OH)6SO4, a natural mineral and patina constituent on the Statue of Liberty, were investigated. Nanostructured brochantite was synthesized using precipitation and microwave-assisted hydrothermal reactions and evaluated in half-cells with Li metal counter electrodes. Reversible capacities >400 mAh/g corresponding to the 2 electron reduction of Cu2+ and discharge potential of 1.8 V versus Li/Li+ were observed in brochantite with a nanoplate morphology.
The electrochemical properties of the jarosite and V3+ jarosite analogue compounds, MN3(SO4)2(OH)6, where M=K, Na and N=Fe, V, were also investigated. A common industrial mining waste byproduct and naturally occurring mineral on Earth and Mars, the jarosite structure can accommodate many different cations and may serve as a good starting point for developing cathodes for batteries beyond Li-ion. Microstructured jarosites were synthesized using microwave-assisted hydrothermal reaction and the electrochemical characteristic were evaluated in half-cells with Li and Na metal.
Detailed characterization using X-ray diffraction, scanning and transmission electron microscopy, and X-ray photoelectron spectroscopy was performed to better understand the structural changes and reaction mechanisms in both brochantite and jarosite systems.
2:45 PM - EE4.8.02
High Volumetric Capacity Three-Dimensional Nanocomposite Secondary Battery Electrodes
Jinyun Liu 1,Junjie Wang 1,Paul Braun 1
1 Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana United States,
Show AbstractLi-ion batteries have been of significant interest due to their high energy density relative to other secondary battery chemistries (but rather low relative to hydrocarbon fuels). Most commercial Li-ion batteries utilize a graphite-based anode, a lithium transition metal oxide cathode, and a liquid or gelled electrolyte. Given the motivation for increasing the energy density of Li-ion batteries, efforts are underway to replace the low volumetric capacity graphite-based anode and for example, the LiCoO2 cathode. As a potential high capacity anode material, Fe3O4 has a theoretical capacity of ca. 926 mAh g-1, is naturally abundant and non-toxic, making it a promising candidate. However, the large volume expansion (~180%) and the induced cracking and pulverization of the active materials during charge-discharge cycling commonly result in a rapid capacity fade. On the cathode side, we have been investigating V2O5. While the voltage of V2O5 is a bit low (2 to 3.5 V) the fact that it possess a high theoretical capacity (442/294 mA h g-1 for three/two Li ions insertion per V2O5 unit formula) provides potential for an overall good energy density. Forming a high volume fraction V2O5 electrode is challenging. Here, we present three-dimensional (3D) high volumetric capacity nanocomposite concepts for both anodes and cathodes. The anode consists of about 5 nm diameter Fe3O4 nanoparticles integrated with a carbon matrix which has a template-free inverse opal structure; while the cathode is an integrated 3D inverse opal of an electrochemically-active V2O5 and graphene in which the low and mass volume fraction of the graphene scaffold enables a high volume and mass fraction active materials within the electrode. The results show that on a full electrode basis, the Fe3O4/C anodes exhibit high electrochemical performance including a volumetric capacity of ~1000 mAh cm-3 over 100 cycles, which significantly exceeds both the practical (~300 mAh cm-3) and theoretical (837 mAh cm-3) capacity of a commercial graphite-based anode. The V2O5/graphene composite cathodes possess a volumetric capacity of ~223 mAh cm-3 (extrapolated to ~613 Wh L-1, which also exceeds that of a LiCoO2 cathode 483 Wh L-1). After 2000 cycles, the cathode capacity has only faded from 288 mAh g-1 (the 1st cycle) to ~203 mAh g-1, and the Coulombic efficiency is stable at around 99.7%. Our investigations indicate this new electrode design may provide performance advantages for both the anode and cathode in secondary batteries.
3:00 PM - EE4.8.03
Virus Templated Nickel Nanofoams for Transition Metal Oxide Battery Electrodes
Alan Ransil 2,Jacqueline Ohmura 2,Angela Belcher 2
1 Materials Science and Engineering Massachusetts Institute of Technology Cambridge United States,2 Koch Institute for Integrated Cancer Research Cambridge United States,3 Biological Engineering Massachusetts Institute of Technology Cambridge United States,2 Koch Institute for Integrated Cancer Research Cambridge United States1 Materials Science and Engineering Massachusetts Institute of Technology Cambridge United States,3 Biological Engineering Massachusetts Institute of Technology Cambridge United States,2 Koch Institute for Integrated Cancer Research Cambridge United States
Show AbstractThe filamentous M13 virus is a high aspect ratio nanoparticle with both surface chemistry and mechanical properties that can be controlled genetically. As such it has proved a powerful platform for ‘wiring’ electronic devices by allowing the assembly of nanostructures with tunable charge transport properties. In this work we use M13 to template metal nanofoams which are employed as current collectors in lithium ion batteries.
Formation of these nanofoams makes use of amino acid residues at three positions on the pVIII major capsid protein: a glutamic and aspartic acid fusion to the protein’s N terminus (E3), a tyrosine to methionine point mutation at site 21 (Y21M), and the lysine residue located at position 14 (L14). The virus particles are first crosslinked through exposure to glutaraldehyde that reacts with the L14 residue to form a hydrogel. These hydrogels can be formed on diverse substrates, such as metal foams and foils, or produced as freestanding gels. The hydrogel is then sensitized by exposure to a palladium-based catalyst that electrostatically binds to the negative surface charge on the virus capsid. Electroless deposition is then used to deposit nickel onto the hydrogel, resulting in a biotemplated foam. The virus offers control over the foam morphology by genetic alteration of its mechanical properties. The Y21M site mutation increases the persistence length of the virus, which lowers the porosity of the resulting nickel foams.
Transition metal oxides are then electrodeposited onto these nanofoams as active material precursors. Electrodeposition pulse number is used to precisely control the deposit thickness on the length scale of tens of nanometers. These electrodes consisting of biotemplated current collectors and electrodeposited active material precursors are then processed at low temperatures in order to produce high-performance batteries. Changes in oxidation with subsequent heat treatment and lithiation steps are studied using XPS, and control over both the transition metal oxidation state and degree of lithiation are demonstrated.
This process results in an internally ‘wired’ electrode in which the biotemplated nickel foam forms a percolating network. Furthermore, strut connectivity and morphology, active material chemistry, and lithium diffusion length through the active material are each independently tunable. By systematically varying the active material thickness, high rate capability electrodes are demonstrated. Lastly, extending this system to study ion diffusion in alternative working ion batteries such as sodium and potassium is considered
3:15 PM - EE4.8.04
Investigation of Li-Ion Solvation in Carbonate Based Electrolytes Using Near Ambient Pressure Photoemission
Matthew Brown 1,Mario El Kazzi 2
1 ETH Zurich Zurich Switzerland,2 Electrochemistry Department Paul Scherrer Institute Villigen Switzerland
Show AbstractWe introduce synchrotron-based near ambient pressure photoemission (NAPP) in conjunction with a liquid microjet as a quantitative analytical probe for the investigation of Li-ion solvation. We investigate the electronic structure of the most commonly employed carbonate based Li-ion battery electrolytes by monitoring the binding energy of the Li 1s orbital. These electrolytes all have high vapor pressures that prevent their study by traditional X-ray photoelectron spectroscopy (XPS) and therefore necessitate the use of NAPP. Experiments were performed with 1 M LiClO4 in aprotic solutions of DMC, a 1:1 mixture of EC:DMC and in DMSO. We also investigated the effect of the addition of 5% water on the 1:1 EC:DMC mixture and solvation in pure water. The observed shifts in Li 1s binding energy can be rationalized by analyzing the donor number of the solvent molecules. The largest donor number for the studied solvents is for DMSO (124.7 kJ/mol). This implies the largest electron cloud around Li+ and better screening of the core-hole—consistent with the lowest recorded binding energy. EC (68.6 kJ/mol) and DMC (63.5 kJ/mol) have much lower donor numbers than DMSO and we observe a higher binding energy—consistent with decreased screening of the core-hole. With the addition of 5% water (101.7 kJ/mol) to the 1:1 mixture of EC:DMC the Li+ binding energy shifts lower by 0.2 eV reflecting the higher donor number of water, and partial solvation by water. We note that the relatively small shift in Li 1s binding energy upon addition of 5% water guarantees that the solvation process is competitive between EC, DMC, and water. Pure solvation by water does not occur as evidenced by the additional shift brought about in pure water solution. Our results make clear that NAPP is sensitive to the local structure surrounding the ions of current state-of-the-art lithium-ion battery electrolytes and we conclude by presenting an outlook to future experiments.
3:30 PM - EE4.8.05
Silicon Alloy Encapsulated with Reduced Graphene Oxide as an Anode Material for High Energy Density Lithium-Ion Batteries
Sang-Hyung Kim 1,Aravindaraj Kannan 1,Hwi Soo Yang 1,Seung-Hyun Yook 1,Hansu Kim 2,Seon Kyung Kim 3,Cheolho Park 3,Dong-Won Kim 1
1 Chemical Engineering Hanyang University Seoul Korea (the Republic of),2 Energy Engineering Hanyang University Seoul Korea (the Republic of)3 Next-G Institute of Technology Iljin Electric Co.Ltd Ansan Korea (the Republic of)
Show AbstractThe growing demand for high-performance rechargeable batteries for applications such as electric vehicles and energy storage systems requires remarkable improvement in the energy density of lithium-ion batteries. It has led to the search for advanced materials with high theoretical specific capacities, which should be abundantly available for large-scale applications. Silicon-based anode materials with high theoretical capacity, low reduction potential and low cost satisfy these requirements. However, the silicon materials undergo large volume changes during the alloying/de-alloying reaction, resulting in pulverization of the electrode. In addition, the large volume change results in the continuous breakdown and formation of solid-electrolyte interphase (SEI) layer during the repeated cycling. These problems coupled with the low intrinsic electrical conductivity of silicon lead to significant capacity fading and low coulombic efficiency, thereby limiting the practical use of silicon materials. Various approaches such as controlling the particle size and morphology, alloying with inert metals, dispersing silicon in conductive matrix and utilizing self-healing binders have been adopted to mitigate these problems. In this work, we synthesized Si-based alloy materials with high specific capacity. To improve their cycling stability, the silicon alloy materials were encapsulated with reduced graphene oxide (rGO). The rGO layer formed on the Si alloy played as a flexible confinement for accommodating volume changes during cycling. And also, its high mechanical strength prevented the pulverization of the electrode. In addition, its 2-dimensional structure enabled to electronically connect the individual Si alloy particles to the current collector. Their interfacial studies and cycling performances are investigated by electrochemical impedance spectroscopy, XPS, FE-SEM, HR-TEM and cycling test. Detailed characterization of the rGO-coated silicon alloy materials along with their electrochemical performance will be presented.
3:45 PM - EE4.8.06
Conductive Polymer Binder for High-Tap-Density Nano-Silicon Material for Lithium-Ion Battery Negative Electrode Application
Hui Zhao 1,Yang Wei 2,Phillip Messersmith 2,Gao Liu 1
1 Lawrence Berkeley National Lab Berkeley United States,2 University of California Berkeley Berkeley United States
Show AbstractHigh-tap-density silicon nanomaterials are highly desirable as anodes for lithium ion batteries, due to their small surface area and minimum first-cycle loss. However, this material poses formidable challenges to polymeric binder design. Binders adhere on to the small surface area to sustain the drastic volume changes during cycling; also the low porosities and small pore size resulting from this material are detrimental to lithium ion transport. This study introduces a new binder, Poly(1-pyrenemethyl methacrylate-co-methacrylic acid) (PPyMAA), for a high-tap-density nano-silicon electrode cycled in a stable manner with a first cycle efficiency of 82% - a value that is further improved to 87% when combined with graphite material. Incorporating the MAA acid functionalities does not change the lowest unoccupied molecular orbital (LUMO) features or lower the adhesion performance of the PPy homopolymer. Our single-molecule force microscopy measurement of PPyMAA reveals similar adhesion strength between polymer binder and anode surface when compared with conventional polymer such as homo-polyacrylic acid (PAA), while being electronically conductive. The combined conductivity and adhesion afforded by the MAA and pyrene copolymer results in good cycling performance for the high-tap-density Si electrode.
4:30 PM - EE4.8.07
The Effect of Chemical Doping on the Lithiation Processes of the Crystalline Si Anode: A First-Principles Study
Chin-Lung Kuo 1,Han-Hsin Chiang 1
1 National Taiwan Univ Taipei Taiwan,
Show AbstractIn this study, we have performed density functional theory calculations and ab initio molecular dynamic simulations to investigate the kinetics and dynamics of the lithiation processes of the doped and undoped c-Si anodes for their application in Li-ion batteries. Our ab initio molecular dynamic simulations showed that the lithiation process of c-Si can be remarkably improved by phosphorus-doping while that for the boron-doped Si is simply comparable to the performance of the undoped Si electrode. To explore the physical origins of the enhanced rate capability of the phosphorus-doped Si anode, we calculated the insertion and migration energy barriers of Li ions in c-Si, and then simulated the mechanical response of the Li-inserted Si matrix under different hydrostatic stresses. Our calculated results showed that boron-doping can effectively lower down the insertion barrier of a Li atom into the Si-matrix but phosphorus-doping may lead to the increment of the Li insertion energy in c-Si. Furthermore, although the diffusion energy barriers of Li may slightly decrease (increase) by ~0.2 eV in the phosphorus (boron)-doped Si matrix, these changes were found to be highly localized within the range of the nearest-neighbor distance. Accordingly, the enhanced lithiation rate in the phosphorus-doped Si electrode cannot be attributed to the increased Li diffusion rate or the reduction of the insertion energy barriers of Li atom into the c-Si electrode. On the other hand, our calculated mechanical response of the Li-inserted Si matrix showed that the phosphorus-doped Si matrix can become more ductile and more easily undergo plastic deformation upon hydrostatic stresses, but on the contrary, the Si matrix may become more brittle and stiffer as it was doped with boron atoms. Our ab initio molecular dynamic simulations also showed that the phosphorus-doped Li-inserted Si matrix can easily undergo structure amorphorization within 10 ps, but the boron-doped and undoped Si matrices can still or mostly hold in the diamond structures within the same elapsed time of MD simulations. These results clearly indicate that mechanical softening of the Si bond network can be one of the major reasons that leads to the enhanced lithiation rate of the phosphorus-doped Si electrode.
4:45 PM - EE4.8.08
Lithium-Ion Solvation and Intercalation at Anode-Electrolyte Interface from First Principles
Mitchell Ong 1,Vincenzo Lordi 1,Erik Draeger 1,John Pask 1
1 Lawrence Livermore National Lab Livermore United States,
Show AbstractLithium-ion batteries are commonly used to power many consumer devices such as handheld phones, laptops, portable music players, and even electric vehicles. The interface between the anode and the electrolyte plays a key role in the operation and performance of lithium-ion batteries. In this work, we use first principles molecular dynamics (FPMD) to examine the solvation of the Li ion at different distances from the graphite anode. We find that as Li+ approaches the anode, the coordination number of solvent molecules decreases suggesting that the Li ion must shed its solvation shell entirely to enter the anode. In addition, we estimate the energy required for intercalation of the Li ion into the graphite anode in the presence of the electrolyte. We find that the energy required for intercalation is dependent on the edge termination of the graphite due to electrostatic interactions between Li+ and the terminating species. We further verify the intercalation energy from our FPMD simulations using the nudged elastic band (NEB) method to find the minimum energy paths for entry as a function of different edge terminations. Our results can be utilized to design improved battery systems that optimize Li-ion transport into the anode material.
5:00 PM - EE4.8.09
Assessing the Ionic Conductivity of Li and Na-Containing Borohydrides
Joel Varley 1,Tae Wook Heo 1,Keith Ray 1,Stanimir Bonev 1,Brandon Wood 1
1 Lawrence Livermore National Lab Livermore United States,
Show AbstractRecent experimental studies have identified a family of alkali borohydride materials that exhibit superionic transition temperatures approaching room temperature and ionic conductivities exceeding 0.1 S/cm–1, making them highly promising solid electrolytes for next-generation batteries. Despite the rapid advances in improving the superionic conductivity in these materials, an understanding of the exact mechanisms driving the transport remains unknown. Here we use ab initio molecular dynamics calculations to address this issue by characterizing the diffusivity of the Li and Na species in a representative set of closoborane ionic conductors. We investigate both the Na and Li-containing borohydrides with icosahedral (B12H12) and double-capped square antiprism (B10H10) anion species and discuss the trends in ionic conductivity as a function of stoichiometry and the incorporation of various dopants. Our results support the borohydrides as a subset of a larger family of very promising solid electrolytes and identify strategies to improving the conductivity in these materials.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
5:15 PM - EE4.8.10
Interface Engineered All Solid-State Li-Ion Batteries Based on Low Temperature Synthesized Garnets
Semih Afyon 1,Jan Broek 1,Jennifer Rupp 1
1 ETH Zurich Zurich Switzerland,
Show AbstractHigh energy densities, variable charge-discharge rates and long cycle lives of Li-ion batteries (LiBs) make them the ideal choice for portable electronics and electric vehicles over other battery technologies. However, conventional liquid electrolytes used in LiBs present safety issues in terms of poor chemical stability, flammability and leakage. Solid state ceramic electrolytes solve these issues with their chemical and thermal stability and at the same time could increase the practical energy densities of LiBs by reducing the amount of packaging needed. In particular the garnet-type cubic Li
7La
3Zr
2O
12 (LLZO) and doped variants are promising solid electrolytes with high Li-ion conductivities in the range of ~10
-4 S/cm at RT, chemical stability against elemental Li, and an enlarged thermal operation window
1. However, all solid state Li-ion batteries constructed with the high Li
+-conducting cubic phase show poor practical performances due to the high electrode – electrolyte interface resistance. Besides, the stability and the practical applications of the garnet-type cubic Li
7La
3Zr
2O
12 (LLZO) against various anode materials haven’t been demonstrated in literature yet. Here, we tackle these issues and report an interface engineered all solid state Li-ion battery based on nano- C/Li
4Ti
5O
12 and the low temperature synthesized-processed fast Li-ion conductor Li
6.25Al
0.25La
3Zr
2O
12.
The novel low temperature synthesis route for cubic Li
6.25Al
0.25La
3Zr
2O
12, results in smaller particle sizes and relatively lower sintering temperatures. Nano crystallites of cubic Li
6.25Al
0.25La
3Zr
2O
12 can be obtained at temperatures as low as 650 °C by a modified sol-gel synthesis – combustion method using mostly nitrate precursors. The sintered green bodies with high relative densities up to 95 % show high bulk Li-ion conductivities in the range of 0.5 x10
-3 S/cm; similar high density and conductivity values are normally reachable using much more elaborate techniques (e.g. hot-pressing, high-energy ball milling, special protective atmospheres, etc.)
2. As a first proof of concept, interface engineered batteries with rougher features reducing the interface resistance are assembled employing the nano-Li
4Ti
5O
12 as an electrode material. The intimate embedding of nano-Li
4Ti
5O
12 into the electrolyte layer is satisfied through the employment of a sacrificial composite organic interface and subsequent slurry coating. All solid state batteries show reversible charge - discharge behavior and stable cycling at slightly elevated temperatures of 75-95 °C. The new synthesis-processing and the interface engineering that will be discussed here enable new pathways and options for the construction and the practical applications of all solid state batteries based on garnet-type cubic Li
7La
3Zr
2O
12 (LLZO) structures.
1 S. Afyon, F. Krumeich, J. L. M. Rupp,
J. Mater. Chem. A,
2015, 3, 18636-18648.
2 V. Thangadurai, S. Narayanan, D. Pinzaru, Chem Soc Rev
2014, 43,
4714-4727.
5:30 PM - EE4.8.11
In Situ Investigation of 2D Electrode Materials by Planar Micro Battery
Jiayu Wan 1,Wenzhong Bao 2,Steven Lacey 1,Dennis Drew 1,Michael Fuhrer 3,Liangbing Hu 1
1 Univ of Maryland-College Park College Park United States,2 Department of Microelectronics Fudan University Shanghai China3 School of Physics Monash University Victoria Australia
Show Abstract2D layered materials such as graphene and MoS2 has long been utilized for battery electrode materials. However, understanding of their intrinsic nanostructure and associated property changes during charging/discharging process is lacking. We developed a planar microbattery for the first time for simultaneously real time and in situ measurement of the intrinsic electrical, optical, and structural properties of 2D electrode materials at single flake level. With this tool, we observed a 100 fold increase in the electrical conductivity on both few layer graphene and MoS2 upon lithiation. The planar microbattery has been also used to guide the design of macroscopic coin cell electrodes, where an enhanced specific capacity of MoS2 electrode was obtained. Moreover, we demonstrate this tool can be coupled with in situ AFM to study MoS2 upon Na-ion intercalation. The planar microbattery is an excellent tool to study a variety of intrinsic properties of electrode materials.
EE4.9: Poster Session III
Session Chairs
Friday AM, April 01, 2016
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - EE4.9.01
A First-Principles Study on the Property of Sn-Doped LiFePO4
Guohua Tao 1,LianXi Hou 1
1 School of Advanced Materials, Peking University Shenzhen China,
Show AbstractThe olivine-type LiFePO4 is widely considered as a promising candidate for Li-ion battery electrodes, yet the applicability in the pristine state is limited due to its poor ionic and electronic conduction. Doping can be employed to enhance the material’s electrical conductivity and its electrochemical performance, however, the role played by the dopant is not fully understood. In this work, we investigate the Sn-doped structures of LiFePO4 by using first-principle density functional theory (DFT) within the generalized gradient approximation (GGA) +U. The analysis show that the band gap decreases from 3.74 eV to 2.95 eV with Sn doping in bulk, which may contribute to the improvement of the conductivity of LiFePO4. The effect of surface doping and the multiple valence doping (+2/+4) have also been examined.
9:00 PM - EE4.9.02
Understanding Oxygen Reduction Reaction (ORR) Mechanism on a Pristine and N-Doped Graphene for Lithium-Air Batteries Using Density Functional Theory
Ji Hye Lee 1,Young Hoon Yoon 1,Seung Geol Lee 1
1 Pusan National University Busan Korea (the Republic of),
Show AbstractThe importance of electrical energy storage has immensely grown in addressing the issues with the exhaustion of fossil fuel and fulfilling the increasing demand of various applications such as portable electronics, electric vehicle and large-scale grid. Lithium-air batteries have been regarded as one of the most promising candidate due to high energy density. Unfortunately, their practical applications are still under an infancy stage owing to many challenges such as poor rate capability, short cycle life and poor round-trip efficiency. These problems are linked to the sluggish ORR kinetics on carbon-based electrode. Therefore, it is critical to develop carbon-based materials and electro-catalysts to enhance the ORR kinetics. Graphene has outstanding physical property and large surface area, but has little catalytic characteristic. Meanwhile, N-doped graphene has been reported as an effective electrode because N-doping into graphene can tailor the electronic property, offer more active sites and improve the electro-catalytic activity for ORR. During the synthesis process, various types of N-doped graphene were formed. N-doped graphene with defects and impurities exhibited electro-catalytic activity. Hence, in order to understand the effect of N impurities and defects and examine how ORR occur on pristine and N-doped graphene, we first considered a pure graphene, graphene with mono-vacancy and N-doped graphene with mono-vacancy as surface models. We proposed various adsorption models for ORR, including O2 and Li as ORR reactants and LiO2 and Li2O2 as ORR products, and calculated the binding energies and electronic properties using density functional theory.
Acknowledgement
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2014R1A1A1004096).
9:00 PM - EE4.9.03
First Principles Study on Enhanced Sodium Diffusion Behavior of N-Doped Graphene Nanoribbon (GNR)
Hong Woo Lee 1,Hye Sook Moon 1,Seung Geol Lee 1
1 Pusan National University Busan Korea (the Republic of),
Show AbstractGraphene nanoribbons (GNRs) can be obtained from carbon nanotubes (CNTs) by chemical oxidation with H2SO4/KMnO4 as oxidizing agent. In case of N-doped CNTs, the N atom is known for making tube walls more reactive. Thus, N-doped CNTs are opened along the longitudinal axis more easily than pristine CNTs, and then N-doped GNRs can be obtained. N-doped GNRs have two possible defects (pyridine-like, pyrrole-like) with N-impurities in unzipping process. Experimentally, N-doped GNRs are reported that improve the capacity and cycling stability of rechargeable batteries. Nowadays, sodium ion batteries (SIBs) are in the spotlight as rechargeable batteries due to sodium’s low cost and natural abundance. However, theoretical mechanism for N-doped GNRs as anodes of SIBs has not yet been fully investigated. In this study, we investigated the diffusion behavior of sodium on N-doped GNRs using density functional theory (DFT). We observed that the diffusion of sodium tends toward the N-doped site in GNRs. It implies that energy barriers of the diffusion of sodium on N-doped GNRs were affected by N-impurities on GNRs.
Acknowledgement
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2014R1A1A1004096).
9:00 PM - EE4.9.04
An Equivalent Circuit Model for Nanostructured Batteries
Hidenori Yamada 1,Prabhakar Bandaru 1
1 ECE Univ of California - San Diego La Jolla United States,2 MAE Univ of California - San Diego La Jolla United States,1 ECE Univ of California - San Diego La Jolla United States
Show AbstractIn order to enhance the capacity of a charge storage device, introducing nanostructures such as 2D graphene or 1D carbon nanotubes (CNTs) increases the surface area exposed to electrolyte. Previous work on nanostructured capacitors has demonstrated the need for new physics based on non-3D density of states (DoS) [1]. Here, for nanostructured batteries, we derive new current-voltage (I-V) formulas based on 2D and 1D DoS and analyze nanostructured battery I-V data. The activation energy for the redox reaction in the battery is dependent on the reorganization energy, which is described through diode elements in a new equivalent circuit model. This activation energy is then applied to an integral expression for current, which involves the DoS, the Fermi-Dirac function, and the partition function. The results are compared to measured chronopotentiometry I-V data on Li-ion batteries with nanostructured electrodes, and good agreement is obtained.
[1] H. Yamada and P. R. Bandaru, Appl. Phys. Lett. 102, 173113 (2013), ibid 104, 213901 (2014).
9:00 PM - EE4.9.05
Correlation of Charge Transfer and Electronic Structure in Lithium Battery Cathodes: How Can We Access and Assess It
Artur Braun 1,Janina Molenda 2
1 EMPA Duebendorf Switzerland,2 AGH Krakow Krakow Poland
Show AbstractBatteries are traditionally studied with respect to their electric properties - hence with electroanalytical methods. With increasing complexity of electrode chemistries and architectures, requirements for analytical studies have become more demanding. Fortunately, there has been analog progress in instrument development at synchrotron radiation centers. We will show how we can probe the relevant valence band of battery cathodes with x-ray absorption and photoemission spectroscopy and how we can assign the conductivity of the electrode for example to particular molecular orbital origin, including hole states which we can "zip out" by a spectroscopic trick called contrast variation. Therefore, the "cartoons" which typically sketch the density of states (DOS) become now real in the sense that we have direct experimental data on lithium and sodium cobalt oxide based battery cathodes, which we show along with their electronic condutivity. The parallelism between electronic structure and electronic charge transport properties is indeed striking. In the end we will show how we can extract related information even in situ or operando from batteries in operation, i.e. charging or discharging.
9:00 PM - EE4.9.06
Magnetic and Electronic Properties of Doped LiMn1.5Ni0.5O4: A First Principles Study
Yu-Hao Tsai 2,Gyeong Hwang 1
2 Materials Science and Engineering Program The University of Texas at Austin Austin United States,1 Department of Chemical Engineering The University of Texas at Austin Austin United States
Show AbstractLiMn1.5Ni0.5O4 has been proposed as a promising cathode material because of its high operating voltage and environmental advantages; however, the performance is sensitive to the synthesis conditions, having significant influences on the composition and stoichiometry. In the nonstoichiometric LiMn1.5Ni0.5O4, the total magnetic moment was experimentally reported to increase with increasing the Mn/Ni ratio, which is likely due to the antiparallel spin alignment between Mn4+ and Mn3+. In this work, we provided theoretical evidences for Mn3+-concentration dependence of spin alignments, through density functional theory/Hubbard model (DFT+U) calculations. For this study, U parameters for Mn, Ni and O were first optimized by fitting to the predicted electronic structures from hybrid-DFT, which turns out to be effective. With the newly optimized U values, we have successfully reproduced relevant experimental results. Our detailed study on the electronic structure of LiMn1.5Ni0.5O4 and LiMn2O4 explores the origin of different lithiation voltages and stabilities of two structures. We also investigated the behavior of dopants (Cr, Fe, Co) near the surface of LiMn1.5Ni0.5O4, together with underlying reasons; our calculations show that Cr and Fe undergo surface segregation while Co stays in the bulk. We then discussed how doping of certain 3d elements enhances the cycling performance and rate capability of LiMn1.5Ni0.5O4.
9:00 PM - EE4.9.07
Design of Nickel-Rich Layered Oxides Using d Electronic Donor for Redox Reactions: First-Principles Prediction and Experimental Validation
Duho Kim 1,Jin-Myoung Lim 1,Young-Geun Lim 2,Ji-Sang Yu 2,Min-Sik Park 2,Kyeongjae Cho 1,Maenghyo Cho 1
1 Seoul National Univ Seoul Korea (the Republic of),2 Advanced Batteries Research Center Korea Electronics Technology Institute Seongnam Korea (the Republic of)3 Department of Materials Science and Engineering and Department of Physics University of Texas at Dallas Dallas United States,1 Seoul National Univ Seoul Korea (the Republic of)
Show AbstractRecently, Ni-rich layered oxides as compared with commercialized LiCoO2 have been extensively studied as an alternative cathode material because of their relatively higher reversible capacity and lower cost. To date, many research groups have tried to resolve critical performance fading (e.g., cyclability and rate capability) by focusing on adjusting and substituting of transition metals (TMs) or non-TMs in the layered oxides. Although studies of developing electrochemical performance from a practical perspective have been variously conducted, a theoretically fundamental understanding of the multicomponent layered oxides has not yet been clearly researched. In our study, through first-principles calculations and experimental observations, we first explain the correlation between the Ni and Mn ratio, leading to the redox behaviors of the layered NCM cathodes. The equilibrium potentials based on redox reactions of Ni2+/Ni3+ are highly dependent on the Mn ratio (NCM523 and NCM721: ∼3.7 and 3.5 V) because of a donor electron, in the eg band, transferred from Mn to Ni owing to their crystal field splitting (CFS) with different electronegativities, leading to oxidation states of Ni2+-like and Mn4+. Considering the d electronic donor based on CFS with electronegativity of TMs, we finally expect V as a promising doping source to provide donor electrons for Ni redox reactions in Ni-rich layered oxides, resulting in higher delithiation potentials (NCV523: 3.8 V). From our theoretical calculations in the NCV oxide, the oxidation states of Ni and V are stable Ni2+-like and V5+, respectively, and the fractional d-band fillings of Ni are the highest value as compared with NCM523 and LiNiO2 because of two donor electrons in the t2g band. Based on the fundamental understanding on the CFS with electronegativity of TMs, it would be possible to design new Ni-rich layered cathodes with higher energy for use in Li-ion batteries.
9:00 PM - EE4.9.08
A Comparative First-Principles Study of Li, Na, and Mg Insertion in Alpha and Beta Sn Including the Effect of Phonons
Sergei Manzhos 1,Fleur Legrain 1,Oleksandr Malyi 2,Clas Persson 2
1 National Univ of Singapore Singapore Singapore,2 Physics University of Oslo Oslo Norway
Show AbstractLi-ion batteries have been the most efficient commercial storage technology. Non-Li-ion batteries (in particular Na- and Mg-ion batteries) are actively investigated for two main purposes (i) in order to propose alternatives to Li-ion batteries for large-scale applications especially for grid storage, (ii) to surpass the performance of Li-ion batteries (e.g. Mg-ion batteries provide potential larger specific capacities). We focus here on the negative electrode of Li-, Na-, and Mg-ion batteries since an efficient anode material – providing a good capacity, at a decent charge/discharge rate, and with a high cycle life – has still not emerged for Na and Mg. In particular, Sn has been shown to be very promising: it provides very good theoretical specific capacities (994 mAh/g for Li, 847 mAh/g for Na, and 903 mAh/g for Mg) which have been approached experimentally.
However, intercalation of Li/Na/Mg is still not fully understood, in particular the formation of the alpha phase with Li intercalation in beta-Sn anodes1 remains perplexing, and DFT results with opposite claims have been reported.1,2 With a transition temperature of 286 K, the alpha and beta phases of Sn have very similar energetics at room temperature, suggesting that any external perturbation (e.g. doping) can reverse the alpha-beta relative stability. We investigated the effect of Li/Na/Mg insertion on the alpha-beta relative stability, including the vibrational contributions, which were not considered in the previous DFT studies. We found that while Mg doping over-stabilizes the beta phase, Li and Na doping stabilize the alpha phase (so as to be more stable than beta-Sn at room temperature) – which could rationalize the formation of alpha-Sn upon Li intercalation. The changes in phase stability are directly related to the defect formation energies for the insertion of Li, Na, and Mg in one phase versus the other. At 300 K, insertion of Li/Na is more favorable in alpha-Sn (-0.37/-0.08 eV) than in beta-Sn (0.06/0.49 eV), while Mg defect formation energy, although positive, is lower in b-Sn (0.53 eV) than in alpha-Sn (0.66 eV). The vibrational contributions were found to affect significantly the defect formation energies, with energy effects of up to 0.13 eV at 300 K. Barrier calculations were also performed for diffusion of Li, Na, and Mg in alpha-Sn and beta-Sn, which were to date not (correctly) reported for Na and Mg. The diffusion of Li/Na/Mg was found to be anisotropic in beta-Sn, with barriers along the (001) direction (0.01/0.22/0.07 eV) significantly lower than that in alpha-Sn (0.20/0.52/0.40 eV).
[1] H. S. Im, Y. J. Cho, Y. R. Lim, C. S. Jung, D. M. Jang, J. Park, F. Shojaei and H. S. Kang, ACS Nano, 2013, 7, 11103.
[2] P. Kaghazchi, J. Phys.: Condens. Matter, 2013, 25, 382204.
9:00 PM - EE4.9.09
A Comprehensive Finite Element Model for Lithium-Oxygen Batteries
Martin Ayers 1,Shadow Huang 1
1 North Carolina State Univ Raleigh United States,
Show Abstract
The development of improved energy storage technologies with greater specific energies is critical to the success of future electric vehicles and renewable energy products. Among the different energy storage technologies under study, lithium-oxygen batteries are one of the most promising due to their greater gravimetric energies and capacities compared to other technologies such as conventional lithium-ion cells. The objective of this research is to develop a comprehensive understanding of how the anodic and cathodic parameters affect the discharge characteristics of lithium-oxygen cells through the use of the finite element method and computational fluid dynamics software ANSYS Fluent. Several major challenges remain in the development of a commercially available lithium-oxygen battery and many studies have been published that separately consider the effects of dendrite growth, species diffusivity, and electrode porosity on a cell’s performance. The growth of dendrite structures on the anode surface can lead to shorts within the cell while the build-up of precipitate within the cathode can lead to pore clogging and capacity loss. Our finite element models consider each of these issues to gain an understanding of their collective effect on the performance of a lithium-oxygen cell. The model will aid in our understanding of the operating behaviors of lithium-oxygen cells and how species diffusivity, electrode porosity, and anode surface homogeneity affect the discharge performance of a lithium-oxygen cell. This comprehensive understanding will aid in the design of a commercially viable lithium-oxygen battery that could be used for a wide range of energy storage applications.
9:00 PM - EE4.9.10
Hierarchical Ni/MnO/Carbon Composites via Cooperative Assembly during Electrospinning for High Capacity Battery Anodes
Sarang Bhaway 1,Yu-Ming Chen 1,Yuanhao Guo 1,Pattarasai Tangvijitsakul 1,Mark Soucek 1,Alamgir Karim 1,Miko Cakmak 1,Yu Zhu 1,Bryan Vogt 1
1 The University of Akron Akron United States,
Show AbstractA facile method to fabricate hierarchically structured composites is described based on electrospinning metal nitrate salts, phenolic resin and block copolymer dope. Carbonization of these fiber mats generates metal oxide nanodomains interconnected by carbon with well-defined mesopores within the fibers. The diameter of the fibers can be tuned by the dope concentrations and spinning conditions. These nanofibers contain arrays of elliptical nanopores (long axis: 32 8 nm) along their length. The electrical conductivity of the fibers can be tuned by the Ni content in the electrospun fiber mats, which intrinsically increases the conductivity as well as promotes graphitization. These materials exhibit excellent high rate performance and long-term cycle stability in both Li and Na ion battery half cells due to:
1. high surface area (150 m2/g) porous nanofibers for facile ion insertion
2. interconnected fiber morphology (both intra- and inter-fiber) inhibits inactive materials in the electrode to facilitate charge transport
3. porosity that accommodates volumetric changes during charge-discharge
Even without added electrically conductive filler (e.g., carbon black), these Ni/MnO/carbon composite nanofibers exhibit a reversible specific capacity of >750 mAh/g at a current density of 50 mA/g with almost 100% capacity retention over 500 cycles as lithium ion battery anodes. This electrospinning strategy utilizing micelle templating synthesis can be readily scalable for roll-to-roll fabrication of high specific capacity, binder-free battery electrodes.
9:00 PM - EE4.9.11
Effects of Crystal Field Stabilization on Phase Transformation in Li-Rich Oxides.
Jin-Myoung Lim 1,Duho Kim 1,Min-Sik Park 2,Kyeongjae Cho 3,Maenghyo Cho 1
1 Seoul National University Seoul Korea (the Republic of),2 Korea Electronics Technology Institute Seongnam Korea (the Republic of)3 the University of Texas at Dallas Dallas United States
Show AbstractFor increasing demand of large scale energy storages, Li-rich oxides have spotlighted due to large specific capacity and high operating voltage. However, Li-rich oxides has a critical challenge related to poor cyclic performances induced by a phase transformation. For this reason, suppressing the phase transformation in Li-rich oxides is an indispensable research direction. Here, we elucidate that crystal field stabilization of transition metal ions has a fundamental role of the phase transformation using both first-principles calculation and experiments. As a key component of Li-rich oxides, Li2MnO3, understanding of the behavior of Mn4+ in the inactive Li2MnO3 by ex-situ X-ray photoelectron spectroscopy and electronic structures is investigated in the point of the crystal field stabilization. Furthermore, the other components such as Ni and Co also are scrutinized by kinetic analysis with the crystal field splitting diagram of the electronic structure. On the basis of these findings, the critical effect of crystal field stabilization on phase transformation in Li-rich oxides is understood such that electron transfers among the consisting atoms to stabilize the crystal field determine whether the phase transformation are caused or impeded. From this mechanism, predictable solutions for impeding the phase transformation are suggested through screening transition metals in the periodic table by first-principles calculation. Based on this study, it is expected that a fundamental framework to resolve the major challenge of poor cyclic stability in Li-rich oxides could be provided.
9:00 PM - EE4.9.12
Carbon Nanotube Papers Capturing Si Nanoparticles for Binder-Free Anodes of Lithium-Ion Batteries
Takayuki Kowase 1,Kei Hasegawa 1,Suguru Noda 1
1 Department of Applied Chemistry Waseda University Tokyo Japan,
Show AbstractSi is a promising candidate material for lithium ion battery anodes due to its high theoretical capacity (4200 mAh/g
Si). However, it suffers from the rapid degradation due to its huge volume change (up to 400%) during charge/discharge cycles. Si anodes with various nanostructures have been developed and encouraging cycle performances have been demonstrated [1]. However, most of them were fabricated with small loads of Si (about 1 μm or less) on thick and heavy Cu current collectors (15 μm or thicker) through complicated processes. For practical application, it is essential to enhance the Si loads through easy and simple processes.
In this presentation, we propose Si-based anodes in which Si nanoparticles (Si-NPs) are captured at a high load within carbon nanotube (CNT) papers through simple processes. Si-NPs were synthesized by rapid vapor deposition method [2], in which Si source was heated to >2000 °C (well above the melting point) and evaporated in <1 min under low-pressure Ar. Sub-millimeter-long few-wall CNTs produced by fluidized bed [3] were used as a current collector and structure matrix. They were shown effective in capturing activated carbon particles for electrochemical capacitor electrodes [4]. Si-NPs and CNTs were co-dispersed and filtrated to yield self-supporting Si-CNT films. Finally, the connection between Si-NPs and CNTs was enhanced by depositing carbon layer on the films by CVD using C
2H
2.
Si-NPs were synthesized with a range of diameter, from a few tens nm at 5 Torr to a few hundred nm at 50 Torr at high yields of 20-60%. Co-dispersion and filtration yielded self-supporting paper, in which CNTs hold Si-NPs uniformly. By appropriate carbon coating, the Si-CNT anodes with Si (synthesized at 10 Torr) loads of 36 wt% and 0.458 mg/cm
2 showed initial discharge capacities of 1519 mh/g
Si (0.696 mAh/cm
2) and retained capacities of 1229 mAh/g
Si (0.563 mAh/cm
2) after 100 cycles at a charge-discharge rate of 0.3 C in 1M LiClO
4 EC/DEC(v/v=1/1) +1wt% VC electrolyte with Li counter electrode. And the Si-CNT anodes with Si (synthesized at 50 Torr) loads of 73 wt% and 0.815 mg/cm
2 showed initial discharge capacities of 1687 mh/g
Si (1.376 mAh/cm
2 ) and retained capacities of 924 mAh/g
Si (0.753 mAh/cm
2) after 100 cycles at 0.3 C.
References
[1] C.K. Chan, et al., Nat. Nanotechnol. 3, 31 (2008)
[2] J. Lee and S. Noda, RSC Adv. 5 (4), 2938 (2015).
[3] D.Y. Kim, et al., Carbon 49, 1972(2011).
[4] R. Quintero, et al., RSC Adv. 4 (16), 8230(2014).
Corresponding Author: S. Noda
Tel&Fax: +81-3-5286-2769
E-mail:
[email protected]Web:http:www.f.waseda.jp/noda/
9:00 PM - EE4.9.13
Porous Silicon–Carbon Anodes Materials Engineered by Simultaneous Chemical Etching for High-Performance Lithium-Ion Batteries
Myungbeom Sohn 1,Dae Sik Kim 1,Hyeong-Il Park 1,Hansu Kim 1
1 Department of Energy Engineering Hanyang University Seoul Korea (the Republic of),
Show AbstractLithium-ion batteries (LIBs) have played a critical role in the development of portable electronics and have gained a great deal of attention as power sources for electric vehicles and large-scale energy storage systems. However, current LIBs reached its technological limits for increasing their energy densities. In order to solve this, extensive research efforts have been devoted to finding high capacity electrode materials to replace currently used materials such as graphite anode in LIBs. Although silicon-based materials are regarded as one of the most promising candidates for anodes because of their high capacity, the huge volume expansion/contraction of Si during cycling lead to drastic capacity degradation. Recently, porous silicon-carbon (Si–C) composite materials have been revealed to accommodate the large volume change of Si, thus showing outstanding electrochemical performances. However, their use in LIBs has suffered from the complicated and limited routes for their synthesis. In this presentation, we represent porous Si–C composite prepared by scalable and nontoxic method using high energy ball milling and chemical etching process as a high capacity lithium storage material for LIBs. This material synthesis concept presented herein represent a means of improving the electrochemical properties of Si-based porous anode materials for use in commercial LIBs.
9:00 PM - EE4.9.14
TiO2 Coated Si/SiOx Nanocomposite Anode Material for Lithium-Ion Batteries
Juhye Bae 1,Dae Sik Kim 1,Hyun Dong Yoo 1,Eunjun Park 1,Ayoung Kim 1,Min-Sik Park 2,Young-Jun Kim 2,Hansu Kim 1
1 Hanyang University Seoul Korea (the Republic of),2 Korea Electronic Technology Institute Seongnam Korea (the Republic of)
Show AbstractSi based anode materials has received much attention because of high theoretical capacity of silicon (3,570 mAh g-1). However, Si based materials are still not widely used as for commercial lithium ion battery because of their poor cycle performance induced by huge volume change of Si during cycling. Among various studies to resolve this problem, SiOx materials are one of the promising materials to show the improved cycle performance compared to Si electrode. In this work, TiO2-coated Si/SiOx nanocomposites were investigated as anode materials for lithium ion batteries. Si/SiOx nanocomposites were synthesized by heat treatment of hydrogen silsesquioxane (HSiO1.5) obtained from sol-gel reaction of triethoxysilane. TiO2 coating layer on the surface were also easily introduced by sol-gel process. TiO2-coated Si/SiOx nanocomposites as anode materials showed stable cycle performance with high reversible capacity of about 1100 mAh g-1. More detailed electrochemical performances and the physicochemical properties of TiO2-coated Si/SiOx nanocomposites materials will be discussed in this presentation.
9:00 PM - EE4.9.16
Ultralong Carbon Nanofiber Grown on Porous Si Particles as an Anode Material for Lithium-Ion Battery
Hyeong-Il Park 1,Myungbeom Sohn 1,Cheolho Park 3,Jeong-Hee Choi 2,Hansu Kim 1
1 Hanyang Univ Seoul Korea (the Republic of),3 Next-Generation Institute of Technology Iljin Electric Co., Ltd. Ansan Korea (the Republic of)2 Korea Electro-technology Research Institute Changwon Korea (the Republic of)
Show AbstractAlthough silicon has higher reversible capacity than graphite, its large volume expansion during lithium insertion causes poor capacity retention. To address this technical issue, porous silicon anode materials have been intensively investigated as silicon based anode material for lithium ion batteries. Among the fabrication methods for porous silicon, dealloying method by selective etching the Si-transition metal alloy with acidic solution has been attracted attentions due to relatively low production cost. Si/Al-Cu-Fe alloy nanocomposite was used as precursor for porous silicon and etched material was coated with carbon by using a pitch as a carbon precursor. In this process, we observed the carbon nanofiber growth on the surface of porous silicon. This grown carbon might be formed probably due to residual Fe impurity after etching, which act as catalyst for the growth of carbon nanofiber. We found that the resulting materials showed high reversible capacity of around 1800mAh g-1 and more stable cycle performance up to 100 cycles than that of etched porous silicon. Electrochemical properties of these materials will be discussed in more detail in the presentation.
9:00 PM - EE4.9.17
Exfoliation Synthesis and Reassembly of Functional LiCoO2 Nanosheets
Qian Cheng 1,Candace Chan 1
1 Arizona State Univ Tempe United States,
Show AbstractThe synthesis and reassembly of Li metal oxide 2D nanosheets into materials with good electrochemical properties is challenging due to interference from strongly adsorbed protons introduced during exfoliation. Here LiCoO2 (LCO) nanosheets were prepared with electrochemical oxidation followed by intercalation of tetraethylammonium cations. The nanosheets were purified using dialysis and electrophoresis, and reassembled with microwave hydrothermal treatment. The O2-polytype of LCO was found existing in nanosheets reassembled particles, indicating that non-equilibrium structures can be obtained using this approach. After annealing, the materials exhibited electrochemical properties characteristic of O3-type LCO with good capacity retention when coated with atomic layer deposited Al2O3. This work shows that the proton exchange step usually required for the exfoliation of layered metal oxides with strong interlayer bonding can be circumvented. Moreover, the obtained nanosheets could be restacked into functional electrode materials without interference from adsorbed protons. This could pave the way for the synthesis of materials with novel structures and electrochemical properties, as well as the fabrication of hybrid and composite structures from different nanosheets as building blocks.
9:00 PM - EE4.9.18
Li-Ion Conversion Reaction Battery Anodes with Metal-Metal Oxide Multilayer Architecture
Fernando Castro 1,Qianqian Li 1,Guennadi Evmenenko 1,D. Bruce Buchholz 1,Jinsong Wu 1,Michael Bedzyk 1,Vinayak Dravid 1
1 Northwestern Univ Evanston United States,
Show Abstract
Although Li-Ion battery technology has advanced significantly, higher capacity electrode materials are desired for widespread utilization in electric vehicles and future grid-level renewable energy storage. Li-ion battery electrode materials that undergo Li conversion, rather than intercalation, are promising next-gen electrodes as they can have capacities 2-3 times higher than intercalation-based electrodes.1,2 One such class of materials consists of 3-d transition metal oxides, which are suitable anode materials given their lower operating potentials vs. Li+/Li. NiO in particular is of interest given its inexpensive cost and high capacity of >700 mAh/g. 3
In order to build a stronger mechanistic understanding of the conversion reaction at the atomic-level, Li-ion anodes based on NiO are studied with an array of Scanning Transmission and Transmission Electron Microscopy (S/TEM). Specifically, we investigate anodes with a Ni/NiO multilayer architecture, as multilayer structures have been shown to control volume expansion and improve cycling lifetimes in related Li-alloy materials. 4 High Resolution TEM imaging and electron diffraction reveal evidence of a top-down lithiation transport mechanism in this system. We also explore imposed structure-property relationships by relating differing layer thicknesses and degrees of crystallinity to the observed extent of lithiation and conversion within the multilayer architecture. X-Ray reflectivity measurements show formation of low electron density regions at interfaces in partially lithiated structures. Electron Energy Loss Spectroscopy measurements determine the composition in these regions, which may be Li-rich and indicate a heterogeneous nucleation mechanism of Li2O or other Li reaction products. Additionally, preliminary in-situ S/TEM lithiation experiments present further insight into the reaction dynamics of this fascinating system.
(1) Poizot, P.; Laruelle, S.; Grugeon, S.; Dupont, L.; Tarascon, J. M. Nature 2000, 407, 496.
(2) Luo, L.; Wu, J.; Luo, J.; Huang, J.; Dravid, V. P. Sci. Rep. 2014, 4.
(3) Cabana, J.; Monconduit, L.; Larcher, D.; Palacín, M. R. Advanced materials 2010, 22, E170.
(4) Fister, T. T.; Esbenshade, J.; Chen, X.; Long, B. R.; Shi, B.; Schlepütz, C. M.; Gewirth, A. A.; Bedzyk, M. J.; Fenter, P. Advanced Energy Materials 2014, 4
Acknowledgment: This work was supported as part of the Center for Electrochemical Energy Science (CEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. This work was also supported by the NUANCE Center new initiatives, and made use of the EPIC facility (NUANCE Center-Northwestern University), which has received support from the NSF MRSEC program (NSF DMR-1121262) at the Materials Research Center, The International Institute for Nanotechnology (IIN); the State of Illinois; and Northwestern University.
9:00 PM - EE4.9.19
Few-Layer Graphene Nanostructures as High-Capacity Lithium Storage Cells for Batteries
Arkady Ilyin 1,Gulzhan Baigarinova 1
1 Kazakh National Univ Almaty Kazakhstan,
Show AbstractThe paper presents computer simulation with density functional theory study of structural and energetic characteristics of few-layer graphene (FLG) nanostructures, as high-capacity storing cells for Li batteries. Results of modeling revealed some features of these systems, which can cause dimensional instabilities and shortening of the life time of Li-based power sources. Data obtained in the work allow of predicting that mechanical and dimensional stability of FLG and their Li-capacity can be in significant measure improved by formation of structural bridge-like radiation defects, securing fast bonding between graphene sheets [1,2]. Results of the work allow to suppose that such FLG materials, modified by bridge-like defects can be applied in production technologies of Li- based batteries with the high electrical capacity and long lifetime.
References
1. A.M. Ilyin, Computer Simulation of Radiation Defects in Graphene and Relative Structures. In : “Graphene Simulation”, Gong, J.R.;Ed.;InTech: Rijeka , CR 39 ( 2011).
2. A.M.Ilyin, N.R.Guseinov, R.R.Nemkaeva, I.A.Tsyganov, S.B.Asanova, V.V.Kudryashov, Nucl. Instrum. & Meth. Phys. Res., B, 315 192 (2013).
9:00 PM - EE4.9.20
Synthesis of LiMPO4 /C Nano-Composites (M=Mn, Co) from M(II) Phosphate Precipitated from a Micro-Mixer Approach
Hui Yang 1,Xiao-Min Liu 1
1 Nanjing Tech University Nanjing China,
Show AbstractOlivine metal phosphates LiMPO4 (M = Fe, Mn, Co, Ni) possess high safety, long cycle life and low cost, making them as one of the most promising candidates for large-scale applications, such as electric vehicles and energy storage systems. Among them, LiFePO4 has been extensively studied in the past two decades and is already commercialized for such applications. Encouraged by its success, recently more interests have been focused on LiMPO4 cathodes with M as Mn or Co, since they exhibit higher potential plateaus, resulting in higher theoretical energy density compared to LiFePO4.
It is well known that the main weakness of bulk Olivine metal phosphates, intrinsically sluggish mass and charge transport, can be circumvented by surface carbon coating on the tailored nanosized particles. Synthesizing nano-sized MxPO4 (x=1 or 1.5) precursors via co-precipitation has been widely employed in the production of nano LiMPO4 from laboratory scale to mass production. Traditionally, the co-precipitation of MxPO4 is carried out by adding Mn+ (n=2 or 3) solution slowly into acidic phosphate solution in a tank under violent stir. In order to obtain nanosized MxPO4 particles during a long batch time, the particle growth and agglomeration must be minimized by either using very dilute reactant solution [1], or introducing in-situ polymerization which covers the surface of each newly formed particle [2], thus hindering the further growth of nuclei. The pure MxPO4 fine particles (nM/nP=x) are only obtained in a very dilute solution with a narrow concentration region of Mn+ and phosphate.
Fundamentally, precipitation is the result of several mechanisms, namely, nucleation, growth and secondary processes (aggregation and breakage), and the driving force is supersaturation. Precipitation processes are generally very fast in which mixing plays a crucial role. Especially, MxPO4 precipitation is a mixing sensitive reaction. The hydrolysis of metal ions and phosphate complicates the reaction process and makes it hard to control. A locally excess of one reactant may induce other secondary reactions in the system. Therefore, the authors report a novel strategy using a micro-mixer to continuously produce nano-MxPO4 particles, which is mixed with LiOH and glucose to prepare LiMPO4/C nano-composites with exceptional high power performance and fast charge capability. More importantly, the strategy adopts an economic and scalable process which can be applied to mass-produce many other uniform nanoparticles with desired purity.
References:
[1] K. Kandori, T. Kuwae, T. Ishikawa, J. Colloid and Interface Sc., 2006, 300, 225.
[2] Y. Wang, Y. Wang, E. Hosono, K. Wang, H. Zhou, Angew. Chem. Int. Ed., 2008, 47, 7461.
9:00 PM - EE4.9.21
Free-Standing Oxide Nanotube Array Electrodes for High Energy Density and Power Density Li-Ion Batteries
Wei Wei 1,Fredrik Bjorefors 1,Kristina Edstroem 1,Leif Nyholm 1
1 Department of Chemistry – Ångström Laboratory Uppsala University Uppsala Sweden,
Show AbstractDuring the past few years, with the increasing power demand generated by applications from portable devices to electric vehicles, more and more emphasis is put on manufacturing high energy and power density Li-ion batteries, i.e., to maximize the capacities while retaining a high rate capability. So far, the studies have been mainly dedicated to the development of powder type electrode materials and relatively little attention has been paid to studies of other electrode architectures. While composite electrodes containing a mixture of the active material powders, binders and conductive additives still are commonly used, such electrodes often yield poor material utilization, undefined material/component arrangements and a lot of complex interfaces. In the present work, we demonstrate that various highly ordered, free-standing oxide nanotube array electrodes, fabricated by electrochemical anodization approaches, can be used either for high energy density and power density Li-ion microbattery applications or as model monolithic electrodes for electrode engineering studies. By using anatase TiO2 nanotube electrodes (as an example of intercalation type electrodes), an areal capacity of 0.37 mAh cm-2 (i.e., 40 mAh g-1) at a rate of 10C (using a (dis-)charge current density of 9 mA cm-2), and 1 mAh cm-2 (i.e., 91 mAh g-1) at a rate of C/5, can be achieved. [1] Well-defined monolithic anatase TiO2 nanotube electrodes with fine-tuned nanotube size gradients (including tube length, diameter and wall thickness) can also be manufactured using a bipolar electrochemistry approach. [2] The gradient nanotube electrodes can provide excellent rate performance, with capacities from of 0.16 mAh cm-2 or 169 mAh g-1 at C/5 rate to 0.04 mAh cm-2 or 42 mAh g-1 at 50C rate. In addition, free-standing Nb2O5 nanotube electrodes, which can be cycled for 10000 cycles with only a 20% loss of initial capacities, can provide unprecedented high-rate performances, i.e., capacities from of 0.1 mAh cm-2 or 110 mAh g-1 at C/5 rate to 0.04 mAh cm-2 or 44 mAh g-1at 100C rate.[3] Some recent work carried out to investigate highly ordered Fe3O4 nanotubular/nanoporous electrodes as a prototype free-standing conversion electrode and V2O5 nanoporous electrodes as free-standing cathodes will also be described. Refs: [1] W. Wei, et al. submitted, 2015 ; [2] W. Wei, et al. Electrochim. Acta 2015, 176, 1393; [3] W. Wei, et al., in preparation, 2015
9:00 PM - EE4.9.23
Facile One Step Synthesis of Nanostructured Ge/GeO2 Composite in Carbon Matrix as an Anode Material for Lithium-Ion Batteries
Sukeun Yoon 1,Jihoon Kim 1,Kuk Young Cho 2
1 Kongju National University Cheonan Korea (the Republic of),2 Department of Materials Science and Chemical Engineering Hanyang University Ansan Korea (the Republic of)
Show AbstractSince the introduction of Li-ion batteries in 1990s by the Sony Corporation, carbonaceous materials have been used as commercial anode materials. Graphite anodes exhibit excellent capacity retention, high Coulombic efficiency, good rate capability, low voltage hysteresis, and low volume expansion during the charge–discharge process but a low theoretical capacity of 372 mAh g-1. However, the usage of Li-ion batteries is being expanded for automotive and stationary storage applications; consequently, higher energy density and power density are desired. As a result, the high theoretical capacity of group IVA materials, such as Si (4200 mAh g-1), Ge (1623 mAh g-1), and Sn (993 mAh g-1), has led to their investigation as alternative materials for graphite anodes in Li-ion batteries. The oxides of these elements are another group of materials that can provide high Li-ion storage. Among these materials, Ge has recently gained attention as a promising anode material because of its high specific gravimetric and volumetric capacity, excellent Li-ion diffusivity (400 times faster than that in Si), and high electrical conductivity (100 times higher than Si) as well as the formation a minimal amount of native oxide in its outermost layer. Despite these highly appealing features, to commercialize these anode materials, critical problems such as their high cost and the mechanical stress caused by the volume change during Li insertion and extraction must be addressed.
We will present a one-step synthesis of a Ge/GeO2/C composite. The motivation for this study is to enhance the capability of Ge for reversible Li storage through the synergistic effect of GeO2 and carbon as well as to investigate the possibility of using Ge/GeO2/C as an anode material for Li-ion batteries and elucidate its reaction mechanism with Li.
9:00 PM - EE4.9.24
Precisely Engineered Colloidal Nanocrystals for Li-Ion and Na-Ion Batteries
Kostiantyn Kravchyk 2,Marek Oszajca 2,Maryna Bodnarchuk 2,Christoph Guntlin 2,Tanja Zuend 2,Shutao Wang 2,Meng He 2,Maksym Kovalenko 2
1 ETH Zurich Zurich Switzerland,2 Laboratory for Thin Films and Photovoltaics Empa Dübendorf Switzerland,
Show AbstractIn recent years, the search for new electrode materials for rechargeable Li-ion batteries (LIBs) has undergone a drastic shift toward nanomaterials [1]. A similar tendency is expected to occur for the conceptually similar Na-ion batteries (NIBs). Due to very short internal diffusion paths, nanoscale materials are far less limited by their ionic or electronic conductivities than their bulk counterparts. Nanomaterials can also withstand much greater mechanical deformation during charge/discharge cycling. Thus, size reduction dramatically reduces the path for mass and charge transport and mitigates the volumetric changes during electrode operation. The smaller the reaction zone, the lower is the kinetic constraint for conversion and alloying reactions [2]. Overall, these favorable effects significantly enlarge the variety of inorganic compounds that can be used as Li and Na ion storage media. With uniform nanomaterials, such as those produced by colloidal methods, one may get clearer insight into the effects of size of cathode or anode materials on their electrochemical cycling stability, capacity and rate capability. For instance, with respect to alloying anode materials (e.g., Sn, Si, and Ge), several reports have shown evidence for the existence of a critical size below which the fracture of a particle may not occur [3, 4].
Herein, we show a specific family of nanomaterials—monodisperse colloidal nanocrystals—for controlling and studying the effects of size, composition, and morphology on electrochemical properties of cathode and anode materials for LIBs and NIBs. In particular, BiF3 and NaFeF3 as example for cathode materials [5] and CoSn2, CoSb2 and FeSn2 as example for anode materials [6] were synthesized in form of colloidal uniform nanocrystals to study size- and structure-dependent effects. In this way, we show that the excellent size-, shape-, and compositional-tunability of colloidal nanomaterials may also open new “degrees of freedom” in battery research.
References
[1] M. Oszajca et al. Chem. Mater., 2014, 26, 5422.
[2] F. Wang et al. JACS, 2011, 133, 18828.
[3] X. Liu et al. ACS Nano, 2012, 6, 1522.
[4] K. Kravchyk et al., JACS, 2013, 135, 4199.
[5] M. Oszajca, et al. Nanoscale, 2015, 7, 16601.
[6] S. Wang et al. submitted.
9:00 PM - EE4.9.25
Silicon Based Nanostructures: From Production to Electrochemical Energy Storage Application
Lisong Xiao 1,Yee hwa Sehlleier 1,Christof Schulz 2,Hartmut Wiggers 2
1 Institute for Combustion and Gas Dynamics – Reactive Fluids (IVG), University of Duisburg-Essen Duisburg Germany,1 Institute for Combustion and Gas Dynamics – Reactive Fluids (IVG), University of Duisburg-Essen Duisburg Germany,2 Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen Duisburg Germany
Show AbstractSilicon has emerged as the most promising component in anode materials for next-generation lithium-ion batteries (LIBs) owning to its natural abundance, relatively low working potential and its high theoretical storage capacity of 3579 mAh/g. However, the practical application of Si based anodes is seriously hindered by its low intrinsic electrical conductivity and its large volume changes (>300%) during charging and discharging. The resulting mechanical stress causes rapid pulverization of the silicon, and isolation and disconnection of the active material from the current collector. These failure events can cause a rapid degeneration of the Si electrode.
In this study, specific Si nanoparticles (NPs) were synthesized in a well-designed hot-wall reactor using monosilane as precursor. This process enables producing high purity Si NPs at a large production rate of up to 0.5-1.0 kg/h. Crystal size, morphology and crystallinity of the Si NPs can be tuned towards optimized properties for battery applications by adjusting the synthesis parameters. In order to overcome the above stated problems and to improve the battery performance of Si NPs-based anodes, Si-carbon nanostructures such as Si-CNT, Si/graphene and Si-CNT/graphene composites have been developed to improve mechanical as well as electrical properties. As highly promising products, Si-CNT/graphene nano-heterostructures demonstrate a high reversible initial capacity of 1665 mAh/g and very stable cycling performance over 500 cycles with a capacity decay of only 0.02% per cycle. Besides, the materials exhibit also high-rate capabilities with 755 mAh/g (45.3% retention) at 10 C. These superior results imply that carbon-based nano-heterostructures can be used for the development of high-performance lithium-ion batteries for durable and high-rate uses.
9:00 PM - EE4.9.26
Highly Reversible Li Insertion into Nanostructured MoO2 Anode Material
Ayoung Kim 1,Eunjun Park 1,Juhye Bae 1,Hansu Kim 1
1 Hanyang Univ Seoul Korea (the Republic of),
Show AbstractMoO2 has gained much attention as a host material for a lithium storage anode material because of its higher gravimetric and volumetric capacity (209 mAh g-1 and 1130 mAh cm-3) than that of LTO (175 mAh g-1, 630 mAh cm-3). However, previous studies showed that MoO2 has poor cycle performance caused by phase transition from monoclinic to orthorhombic phase during lithium intercalation and de-intercalation. In this work, nanostructured MoO2 were prepared by simple solid state synthesis and investigated as an anode for lithium ion battery. Nanostructured MoO2 showed highly stable capacity retention as high as 84% of the initial capacity after 100 cycles, indicating highly stable lithium ion insertion and extraction into MoO2 lattice. More detailed electrochemical performances of MoO2 and ex-situ analysis of lithium intercalated MoO2 anode will be discussed in this presentation.
9:00 PM - EE4.9.27
Transition Metal Dichalcogenides-Based Composites: High Capacity Anode for Advanced Li-ion Battery
Chuanfang (John) Zhang 1,Andres Seral-Ascaso 1,Sang Hoon Park 1,Oskar Ronan 1,Valeria Nicolosi 1
1 Trinity College Dublin Dublin Ireland,
Show AbstractThe rapid development of portable electronics require powerful energy storage devices, especially Li-ion batteries (LiBs). Recently, the non-graphene two-dimensional (2D) materials were received huge research attention as promising LiBs electrodes.1 Transition metal dichalcogenide (TMD) is a family of materials consisting of 40 compounds with a generalized formula of MaXb, where M is a transition metal typically from groups 4–7, and X is a chalcogen such as S, Se or Te.2 Here we report on several MaXb compounds as promising LiB anode materials, where M is gallium or indium, X is sulfur or selenium. The MaXb with different dimensions/morphologies, for example, nanorods, nanotubes, nanoplatelets and nanosheets, were synthesized by different methods and then hybridized with carbon naontubes. The electrochemical performances of the composites were systematically studied. Comparing to the indium class, the gallium class exhibits higher specific capacity at lower current density but relatively poorer rate capability, for instance, the GaS nanosheets display 800 mAh g-1 at 100 mA g-1 and retains 34% at 1000 mA g-1, while InS nanoplatelets display 450 mAh g-1 at 100 mA g-1 and retains 60% at 1000 mA g-1, which could be explained as higher electric conductivity in the latter. Similarly, selenide class performs better than the sulfide class. For the effect of morphology, it shows that nanotubes and nanosheets out-perform the nanorods or nanoplatelets, probably due to higher surface area and more accessible active sites in the former case. Moreover, lower a/b ratio also results in superior electrochemical performances, especially the cycling stability. Finally, we found that through using the electrolyte additive, the formation of solid-electrolyte interphase (SEI) could be suppressed, resulted in much improved cycling performance and rate capability in the studied MaXb. We believe these results would be much helpful in strengthening the understanding of TMDs, especially in screening the proper TMDs as anode materials for advanced LiBs.
References
1 Y. Li, Y. Liang, F. C. Robles Hernandez, H. Deog Yoo, Q. An and Y. Yao, Nano Energy, 2015, 15, 453–461.
2 M. Chhowalla, Z. Liu and H. Zhang, Chem. Soc. Rev., 2015, 44, 2584–2586.
9:00 PM - EE4.9.29
Improving the Lithium-Storage Properties of Self-Grown Nickel Oxide by TiO2 Nanoparticles Interface
Muhammad Sadeeq Balogun 1,Minghao Yu 1,Xihong Lu 1,Yexiang Tong 1
1 Sun Yat-Sen University Guangzhou China,
Show AbstractThe low capacity of conventional graphite when used as an anode in lithium-ion batteries (LIBs) has made metal oxides become important lithium-ion battery anode materials. [1, 2] This is due to their high theoretical capacity the safe role they play during the electrochemical process because of their high potential around 1.0 V, which could avoid the problem of lithium plating at very low potential. [1] NiO is one of the most common metal oxides, considering its abundancy and low cost, it is also a promising anode material for LIBs. [3] Compared to its theoretical capacity, after long electrochemical cycles, the continuous loss in the capacity of nickel oxide (NiO) hinders its practical application as anode material for lithium-ion batteries. The need to improve the lithium-storage performance and retention capacity of NiO becomes essential for the accomplishment of high-performance lithium-ion batteries.
In this respect through a one-pot hydrothermal process, we have fabricated 3D NiO/TiO2 nanocomposites and demonstrated an improvement in the lithium-storage properties of NiO. [4] The excellent performance of the 3D NiO/TiO2 electrode is due to the excellent properties of the TiO2 nanoparticles (their good cyclic stability and low volume change) and the interface between the NiO and TiO2 nanoparticles. Obviously, the NiO/TiO2 nanocomposite recorded a higher areal capacity over the 3D NiO. The nanocomposites exhibit exceptional cyclic performance and rate capability with an areal capacity of 1.49 and 0.78 mAh cm-2 at current densities of 1.0 and 6.0 mA cm-2, respectively. A full cell lithium ion battery was assembled based on the 3D NiO/TiO2 anode and a commercial LiCoO2 cathode, in order to demonstrate its potential application. The NiO/TiO2//LiCoO2 cell shows a specific capacity of 0.13 mAh cm-2 at a current density of 0.2 mA cm-2 after 100 cycles. This work is expected to be of advantage in the development of nanostructured NiO, understanding of higher specific capacity NiO-based anodes and suitable for the low-cost large-scale production of NiO-based nanocomposites.
References
[1] P. Poizot, S. Laruelle, S. Grugeon, L. Dupont, J. Tarascon, Nature 2000, 407, 496.
[2] J.-M. Tarascon, M. Armand, Nature 2001, 414, 359.
[3] B. Varghese, M. Reddy, Z. Yanwu, C. S. Lit, T. C. Hoong, G. Subba Rao, B. Chowdari, A. T. S. Wee, C. T. Lim, C.-H. Sow, Chem. Mater. 2008, 20, 3360.
[4] M. S. Balogun, W. Qiu, Y. Luo, Y. Huang, H. Yang, M. Li, M. Yu, C. Liang, P. Fang, P. Liu, ChemElectroChem 2015, 2, 1243.
9:00 PM - EE4.9.30
Three-Dimensional, High-Porosity Conducting Hybrid Skeletal Structure from Vapor-Phase Polymerized Conformal Surface Layer
Kuk Young Cho 1,Jihoon Kim 2,Jin-Heong Yim 2
1 Hanyang University Ansan Korea (the Republic of),2 Advanced Materials Engineering Kongju National University Cheonan Korea (the Republic of)
Show AbstractThree-dimensional (3D), foam-like conducting open skeletal structures based on hybrid materials exhibiting not only high porosity with giga pores but also electric conducting property has been successfullly fabricated. Assembly of microparticles from degradable materials played as sacrificial template for nanoscale thickness of conducting surface conformal layer. Vapor phase polymerization allowed facile and non-invasive coating of hybrid materilas in a relatively short processing time (30 min). As the new structure supply electric conducting open porous structures with a porosity greater than 96%, the fabricated skeletal structure shows potential for use as conducting components in green electronics and energy applications.
9:00 PM - EE4.9.31
Realization of 5mAh/cm2-Level Cathode Electrode for High Density Li-Ion Battery
Haisol Nam 1,Jaephil Cho 1
1 UNIST Ulsan Korea (the Republic of),
Show AbstractRecently, the electrochemical energy storage system for the portable electronic devices such as Li-ion batteries (LIBs), are coming into the spotlight due to the high energy density and operating voltage. The cathode active material is a key component of the LIBs in determining the direct cell capacity because it contains lithium ions which directly participate in electrochemical reaction. Among a various kinds of the cathode materials used in LIBs, LiCoO2 is the most successfully commercialized cathode material due to its high energy density and easy synthesis method. Although it has a high theoretical capacity of 247 mAh g-1, the real capacity that LCO could deliver is only about 160 mAh g-1 with a cut-off voltage range between 4.3 and 3V (full cell). As the LIBs are used in various applications currently, and those devices require higher energy density to satisfy the customer’s needs, many researchers have been studied to use more lithium ions in the LCO to increase the reversible capacity, thus the energy density, by increasing the cut-off voltages to over 4.3V. But the problem is, when the cut-off voltage gets higher than 4.3V, the structural instability via irreversible phase transition from hexagonal to monoclinic appears during charging/discharging process and also severe side reactions between the electrolyte and the surface of the LCO cathode material occurs, which result in the cobalt dissolution.
One of the effective methods to solve the problems is the surface coating with materials such as metal oxides, metal phosphates, and metal fluorides. These coating materials can effectively reduce the side reactions and suppress the dissolution of the cobalt ion in the structure, but increases the charge transfer resistance, leading to the degradation of the rate capability.
In this study, we suggest N-coated LiCoO2 by using well-known wet treatment and followed by calcination process. The electrochemical properties were investigated in both voltage range 3 – 4.3V and 3 – 4.5V for half-cell configuration. As the cut-off voltage is increased, the reversible capacity increases from ~180 mAh g-1 to ~210 mAh g-1. Furthermore, to see the coating effect clearly, the electrochemical performance of full-cell with natural graphite as the anode material was evaluated with a cut-off voltage range 3 – 4.4V at both room temperature and high temperature.
9:00 PM - EE4.9.32
Electrochemical Evaluation of V2O5 Coatings Grown by Atomic Layer Deposition
D Vernardou 2,M Apostolopoulou 2,N Katsarakis 2,E Koudoumas 2,I Kazadojev 4,S O'Brien 4,Martyn Pemble 4,Ian Povey 4
2 Technological Educational Institute of Crete Heraklion Greece,3 Foundation for Research amp; Technology-Hellas Heraklion Greece,2 Technological Educational Institute of Crete Heraklion Greece4 Tyndall National Institute-UCC Cork Ireland1 Chemistry Univ College Cork Cork Ireland,4 Tyndall National Institute-UCC Cork Ireland
Show AbstractThe atomic layer deposition (ALD) of vanadium pentoxide on fluorine doped tin dioxide coated glass substrates has been examined. Growth was performed by employing Tetrakisdimethylaminovanadium with either water, oxygen or oxygen/argon plasma as the co-reagent. It was observed that only the plasma assisted ALD material was crystalline as grown, with all samples requiring a one hour 400°C to give material that demonstrated well orientated material that exhibited long term stoichiometric stability. The optical properties, morphology and crystallinity are discussed with respect to the materials' electrochemical performance. More specifically intercalation-deintercalation rates and the charge storage capacities.
9:00 PM - EE4.9.33
New Insights into Synthesis of Graphene Oxide Nanoflakes and Electrochemical Performance as Sodium-Ion Battery Electrodes
Harrison Gunn 1,Victoria Voigt 2,Muhamed Kolathodi 2,Gurpreet Singh 2
1 Department of Chemical Engineering Syracuse University Syracuse United States,2 Mechanical and Nuclear Engineering Kansas State University Manhattan United States
Show AbstractHummer’s process was modified to produce gram levels of 2-dimensional nanosheets of graphene oxide (GO) with varying degree of exfoliation and chemical functionalization. This was achieved by varying the weight ratios and reaction times of oxidizing agents used in the process. Based on Raman and Fourier transform infrared spectroscopy we show that potassium permanganate (KMnO4) is the key oxidizing agent while sodium nitrate (NaNO3) and sulfuric acid (H2SO4) play minor role during the exfoliation of graphite. Tested as working electrode in sodium-ion half-cell, the GO nanosheets produced using this optimized approach showed high rate capability and exceptionally high energy density of ~500 mAh/g for up to at least 100 cycles, which is among the highest reported for sodium/graphite electrodes. The average Coulombic efficiency was approximately 99 %.
Symposium Organizers
Mariappan Parans Paranthaman, Oak Ridge National Laboratory
Ayyakkannu Manivannan, USDOE/NETL
Yang-Kook Sun, Hanyang University
Donghai Wang, The Pennsylvania State University
Symposium Support
Aldrich Materials Science
EE4.10: Beyond Lithium
Session Chairs
Friday AM, April 01, 2016
PCC West, 100 Level, Room 103 AB
9:30 AM - EE4.10.01
Few Layer MoS2/graphene/Au-Cu Pentacle Composite Based Paper Anode for Sodium Battery and Supercapacitor Application
Manish Singh 1,Swagotom Sarker 2,Litao Yan 2,Hongmei Luo 2,Rajiv Mandal 1,Bratindranath Mukherjee 1
1 Dept of Metallurgical Engineering Indian Institute of Technology(BHU) Varanasi India,2 Chemical amp; Materials Engineering Department New Mexico State University Las Cruces United States
Show AbstractSodium batteries are cheaper alternative of well established high energy density lithium batteries. However, development of stable high energy density sodium batteries is pegged by challenges like selection of anode material, electrolyte, stability of electrode electrolyte interface face. These issues mainly arise from larger cationic size of sodium compared to lithium leading to gerater change in host structure which finally results in massive failure in cyclic stability. In this work these issues have been addressed by fabricating a few layer MoS2/graphene/Au pentacle composite paper based anode. Here graphene renders both mechanical stability and higher electrical conductivity. MoS2 also being a graphene like 2D material albeit with larger spacing between layers acts as a better host for sodium ions. Au-Cu pentacles with unique plasmonic band in NIR and possessing non crystallographic point group in its form, acts as an efficient stabilizing agent for 1 T MoS2 phase and inhibits it to restack to its bulk form. MoS2 has been prepared through a hydrothermal route and exfoliated with Na-napthalenide in tetrahydrofuran and finally stabilized in aqueous medium. Au-Cu pentacles was prepared in an aqueous medium and mixed with appropriate amount of graphene oxide and PEG and finally vacuum filtered through a PVDF membrane to form the paper. This paper is reduced in HI vapour to form the composite paper anode for sodium battery and capacitor. The composite has been characterized through SEM, HRTEM, XRD, UV-Visible-NIR absorption spectroscopy and raman spectroscopy. Electrochemical performance of the composite paper has been evaluated as a counter electrode against Na foil in half cell configuration. Electrde showed stable charge capacity above 300 mAh gm-1 and excellent sodium cycling ability.
9:45 AM - EE4.10.02
A Functional Electrolyte Promotes New Reaction Pathway for High-Performance Lithium-Sulfur Batteries
Shuru Chen 1,Fang Dai 1,Mikhail Gordin 1,Zhaoxin Yu 1,Yue Gao 1,Jiangxuan Song 1,Donghai Wang 1
1 Pennsylvania State Univ University Park United States,
Show AbstractLithium-sulfur (Li-S) batteries have recently received great attention, as they promise to provide energy density far beyond state-of-the-art lithium ion batteries (LIBs). However, dissolution of lithium polysulfide intermediates in conventional Li-S electrolytes results in very poor overall cell performance. Moreover, due to the increasing in electrolyte viscosity, it forces large amounts of electrolyte to be used, driving down practical cell energy density. To address these issues, we report a functional electrolyte system. Investigation of the functional electrolyte system using in operando proton nuclear magnetic resonance (1H NMR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscope (SEM), and other techniques showed that the functional electrolyte enables a new electrochemical reduction pathway for sulfur cathodes by formation and subsequent reduction of soluble functional polysulfide species. This pathway involves additional electron transfer to break the disulfide bond, enabling a much higher discharge capacity for cells using the same amount of electrolyte. Moreover, the intermediate functional lithium sulfides show better redox kinetics than conventional lithium polysulfides and Li2S, and seem to not increase viscosity of the electrolyte as lithium polysulfides do, thus allowing use of a much lower E/S ratio while maintaining good performance. When a low E/S ratio of 5 and high-sulfur-loading (4 mg cm-2) cathodes were used, cells with this electrolyte system still achieved stable capacities of around 1,000 mAh g-1 sulfur, the highest-reported capacity to date under such harsh conditions. These findings demonstrate the great promise of this functional electrolyte system for further study and future practical applications.
10:00 AM - EE4.10.03
Soybean-Derived 3-in-1 Carbon Structure for High-Performance Lithium-Sulfur Batteries
Guofeng Ren 1,Shiqi Li 2,Zhaoyang Fan 1
1 Department of Electrical and Computer Engineering Texas Tech University Lubbock United States,1 Department of Electrical and Computer Engineering Texas Tech University Lubbock United States,2 Department of Science and Technology Chongqing Public Security Bureau Chongqing China
Show AbstractThe highly insulating nature and easily dissolution tendency of sulfur and polysulfides are two formidable challenges that must be addressed in order to develop practical and cost-effective Li-S battery technology. A conductive bicontinuous framework is commonly used to alleviate the insulating issue, while physical confinement through mesoporous/microporous hierarchical structure or chemical immobilization by chemical bonding is under investigation to address the dissolution problem. However, most structures reported so far either are too complex to be economically practical, or require considerable amount of inactive materials, leading to low sulfur loading.
Here we demonstrate that soybean, with its high protein (nitrogen) concentration, is an excellent precursor to obtain carbon structure that integrates the above three functions together. Such a cost-effective soybean-derived 3-in-1 carbon structure, when loaded with sulfur at 2-6 mg/cm2, exhibits a high capacity of 1200- 900 mAh/g and high cycling stability (less than 0.1% capacity fading per cycle), indicating its great potential for practical Li-S technology development. We will report in detail the process to achieve such 3-in-1 carbon structure and its physical, chemical and electrochemical properties, particularly the Li-S cell performance when used such a structure for sulfur cathode.
10:15 AM - EE4.10.04
Advanced Sulfur Cathode Enabled by Highly Crumpled Nitrogen-Doped Graphene Sheets for High-Energy-Density Lithium-Sulfur Batteries
Jiangxuan Song 1,Zhaoxin Yu 1,Qingquan Huang 1,Yue Gao 1,Donghai Wang 1,Shuru Chen 1
1 Pennsylvania State Univ State College United States,
Show AbstractLithium-sulfur (Li-S) batteries are being pursued as the next generation rechargeable battery due to their high theoretical energy density (2600 Wh/kg) and low-cost.1 However, practical applications of Li-S batteries are highly hindered by the low electrical conductivity of sulfur and the diffusion of soluble lithium polysulfides intermediates generated during cycling, which lead to lower utilization of sulfur, loss of active material from the cathode, and polysulfide shuttle phenomenon. As a result, Li-S cells experience a fast capacity fading, low Coulombic efficiency, and poor rate capability. To address these issues, various type of cathode materials, including porous carbon-sulfur, low-dimensional conducting material (such as carbon nanotube and graphene)-sulfur, and conducting polymer-sulfur composites, have been exploited to improve the overall electrochemical performance of the Li-S cells. Despite the promising advances, the preparation of sulfur cathodes with long-cycle-life and high Coulombic efficiency still presents challenge, especially for the cathodes with high sulfur content in the cathode and high areal sulfur loading in the electrode, which is necessary toward high-energy-density Li-S battery.
Recently, nitrogen-doping of carbon has been demonstrated to be an effective approach for improving the overall electrochemical performance of sulfur cathodes in Li-S batteries.2, 3 Nitrogen-doping, first, can promote chemical bonding between carbon scaffold and sulfur chains upon heat treatment during the sulfur loading process. Secondly, it can also greatly enhance the adsorption of soluble lithium polysulfides intermediates, with 10 times greater adsorption than traditional oxides absorber. Herein, we report a synthesis of highly-crumpled nitrogen-doped graphene sheets with ultra-high pore volume (5.4 cm3/g) via a simple thermally-induced expansion strategy in absence of any templates. The wrinkled graphene sheets are interwoven rather than stacked, enabling rich nitrogen-containing active sites. Benefiting from the unique pore structure and nitrogen-doping induced strong polysulfide adsorption ability, lithium-sulfur battery cells using these wrinkled graphene sheets as both sulfur hosts and interlayer achieved a high capacity of ~1000 mAh/g and exceptional cycling stability even at high sulfur content (≥80 wt%) and sulfur loading (5 mg-sulfur/cm2). The high specific capacity together with the high sulfur loading push the areal capacity of sulfur cathodes to ~5 mAh/cm2, which is outstanding compared to other recently developed sulfur cathodes and ideal for practical applications.
1. Yang, Y.; Zheng, G.; Cui, Y. Chem. Soc. Rev. 2013, 42,3018.
2. Song, J.; Xu, T.; Gordin, M. L.; Zhu, P.; Lv, D.; Jiang, Y.-B.; Chen, Y.; Duan, Y.; Wang, D. Adv. Funct. Mater. 2014, 24,1243.
3. Song, J.; Gordin, M. L.; Xu, T.; Chen, S.; Yu, Z.; Sohn, H.; Lu, J.; Ren, Y.; Duan, Y.; Wang, D. Angew. Chem. Int. Ed. 2015, 54, 4325.
10:30 AM - EE4.10.05
Performance Optimization of Hybrid Electrochemical Capacitors
Richa Agrawal 1,Chunlei Wang 1
1 Florida International University Miami United States,
Show AbstractThe concept of a hybrid electrochemical capacitor which combines a faradaic type battery electrode and an electrochemical double layer type capacitive electrode has gained much attention in recent years. The idea behind using such a capacitor is that the synergy between the two electrode types can lead to realization of high specific power, high specific energy and high cycle life. Intuitively, such a “hybrid” would combine the benefits of both rechargeable batteries and electrochemical capacitors. However, combining two electrochemically very distinct electrodes in one system leads to several challenges that need to be addressed in order to achieve an optimized system. For instance, the energy of such a device is automatically limited by the capacitive electrode, whereas the power and cycle life are dictated by the faradaic electrode. Much work in recent years has focused on addressing the capacity mismatch between the two electrodes through adjusting the mass and thickness of individual electrodes. However, factors like optimal cell voltage, state of charge (SOC), effect of electrode porosity, operational temperature have not been thoroughly investigated. These factors as studied for faradaic and nonfaradaic individual electrodes can have a profound effect on balancing hybridized system as well. In this talk the effects of these factors will be addressed along with experimental verification.
10:45 AM - EE4.10.06
Nanoconfinement of Polymer, Ionic Liquid and Polymer Ionic Liquid Blends for the Fabrication of Battery Electrolytes
Indumini Jayasekara 1,Mark Poyner 1,Dale Teeters 1
1 The University of Tulsa Tulsa United States,
Show AbstractSolid state lithium ion batteries because of the ability of the solid electrolyte to enhance cycle life, promote stability and general make the battery system safer, will be increasing used in electronic devices . In this vein, solid polymer electrolytes and gel polymer electrolytes are very popular today because of their higher mechanical strength and safety compared to liquid system. Ionic liquids have excellent ionic conductivity and very low vapor pressure at room temperature. These properties allow ionic liquids to be incorporated in to polymer structures to enhance the conductivity of polymer electrolytes while still keeping the desired properties mentioned above. Therefore, ionic liquids are useful to enhance conductivity of room temperature batteries as well as for their safety.
In this work, polymer and ionic liquid electrolytes are confined in alumina nanopores in order to further increase ionic conduction. Nanoscale confinement helps to increase the thermal and mechanical stability as well. We have successfully confined the polymer electrolyte, poly(ethylene oxide) complexed with LiSO3CF3 salt and polymer electrolytes blended with ionic liquids in an alumina nanoporous supporting structure. These polymer in nanoporous alumina membranes form a composite system that can achieve stable room temperature batteries with high ionic conductivity. Nanoconfinement has the potential to increase ionic conductivity of polymers due to changes in crystallinity, alignment of polymer chains and interactions with alumina surfaces. Scanning electron microscopic images will be used to confirm the formation of solid/gel polymer nanostructures. DSC and XRD characterization techniques will be used to characterize the changes in crystallinity upon confinement in nanochannels. AC impedance spectroscopy will be used to compare specific conductivity values lending information about the effects of confinement. Further, TGA is used to find the thermal stability changes before and after the nanoconfinement. The mechanism of enhanced ionic conduction and enhanced thermal stability will be discussed.
11:30 AM - EE4.10.07
A Comparative Study on Cubic Li6.4Al0.2La3Zr2O12:Li6.4Ga0.2La3Zr2O12 Garnet Solid Solution
Daniel Rettenwander 1,Reinhard Wagner 1,Lei Cheng 4,Marca Doeff 2,Guenther Redhammer 1,Martin Wilkening 3,Georg Amthauer 1
1 Dept. Material Science amp; Physics University of Salzburg Salzburg Austria,2 Lawrence Berkeley National Laboratory, Environmental Energy Technologies Division University of California Berkeley United States,4 Department of Materials Science and Engineering University of California Berkeley United States2 Lawrence Berkeley National Laboratory, Environmental Energy Technologies Division University of California Berkeley United States3 Christian Doppler Laboratory for Lithium Batteries, and Institute for Chemistry and Technology of Materials Graz University of Technology Graz Austria
Show AbstractLi7La3Zr2O12 garnets and variants1 are one of the most promising Li-ion conducting solid electrolytes. They are exceptionally well suited to be used as protecting layers to enable next-generation Li-metal based battery concepts, e.g., Li/air, Li/sulfur, and Li-flow batteries.
LLZO garnets occurs in a low conducting tetragonal (space group (SG): I41/acd, No. 142)2 and a highly conducting cubic modification (SG: Ia-3d, No. 230)3, whereby the latter has to be stabilized at room temperature (RT) by supervalent substitution.4 The most promising and extensively studied supervalent cations are Al3+ and Ga3+. Much experimental as well as theoretical effort has been undertaken to collect information on the site preferences of Al3+ and Ga3+ as well as the influence on Li-ion dynamics and Li-ion conduction in LLZO garnets.5 It has been shown that the Li-ion dynamics and conductivity of LLZO stabilized with Ga3+ is twice as high compared to its counterpart that is stabilized with Al3+, whereby the reasons remain concealed.5 Quite recently, some of us showed that LLZO:Ga crystallizes, in contrast to LLZO:Al, in a different cubic space group SG: I-43d (no. 220) which probably explains the different electrochemical performance of these two compositions.6
In order to understand the influences of Al3+ and Ga3+ in the LLZO garnet system on crystal- and electrochemical properties in more detail, we performed a systematic study on mixed stabilized Li7-3xAl0.2-xGayLa3Zr2O12 garnets. We used single crystal X-ray diffraction, impedance spectroscopy (IS) over a wide temperature range (− 120 °C to RT) using blocking electrodes, as well as IS in a symmetrical Li-cell setup7 to correlate electrochemical properties with local structures.
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Murugan, R.; Thangadurai, V. Weppner, W.: Angew. Chem. Int. Ed. 2007, 46, 7778.
Awaka, J.; Kijima, N.; Hayakawa, H.; Akimoto, J. J. Solid State Chem. 2009, 182, 2046-2052.
Awaka, J.; Takashima, A.; Hayakawa, H.; Kijima, N.; Idemoto, Y.; Akimoto, J. Key Eng. Mater. 2011, 485, 99-102.
Buschmann, H.; Dölle, J.; Berendts, S.; Kuhn, A.; Bottke, P.; Wilkening, M.; Heitjans, P.; Senyshyn, A.; Ehrenberg, H.; Lotnyk, A.; Duppel, V.; Kienle, L.; Janek, J. Phys. Chem. Chem. Phys. 2011, 13, 19378-19392.
Rettenwander, D.; Langer, J.; Schmidt, W.; Arrer, C.; Harris, K.; Terskikh, V.; Goward, G.; Wilkening, M.; Amthauer, G. Chem. Mater. 2015, 27, 3135–3142.
Wagner. R., Redhammer, G., Rettenwander, D.; Maier, M. E.; Amthauer, G. 2015, submitted.
11:45 AM - EE4.10.08
Large Scale Differential Scanning Calorimetry of Partial or Complete Li-Ion Coins for Determination of Key Safety and Performance Characteristics
Peter Ralbovsky 1
1 NETZSCH Instruments NA LLC Burlington United States,
Show AbstractStandard Differential Scanning Calorimetry (DSC) is commonly used as a technique to look at chemical compatibility and thermal stability of battery components and SEI formation. This method typically requires the creation of a cell which is subjected to the necessary charge/discharge protocol. After the appropriate pre-treatment, the cells (often coin or button cells) are then disassembled in a glove box and the necessary pieces harvested and then sealed in a DSC pan. Then the pan can be removed from the glovebox and analyzed. This method can be laborious and error prone, especially when multi-phase samples are prepared. Non-reproducibility of such tests is a common issue.
A new DSC technique was developed which allows for the accurate measurement of standard coin cell-sized samples, removing the necessity of harvesting and repacking the sample into a DSC pan. Like a standard DSC, the instrument can be run in both scanning and isothermal mode so it is possible to also test cells during cycling and monitor the voltage in scanning tests during heating. In our lab we have used such tests to look at changes in thermal decomposition by changing chemistries, cycling histories and separators. We have also used the calorimeter to get accurate efficiency data independently for both charge and discharge as a function of time and temperature.
12:00 PM - EE4.10.09
In Situ Environmental Transmission Electron Microscopy (ETEM) Study of Thermal Degradation of Nickel-Based Cathode Materials
Khim Karki 2, Yiqing Huang 2,Stanley Whittingham 2,Eric Stach 1,Guangwen Zhou 2
1 Center for Functional Nanomaterials Brookhaven National Laboratory Upton United States,2 NECCES at Binghamton University Binghamton United States,2 NECCES at Binghamton University Binghamton United States1 Center for Functional Nanomaterials Brookhaven National Laboratory Upton United States
Show AbstractIntercalation-based LiNi0.8Co0.15Al0.05O2 (NCA) and LiNi0.3Co0.3Mn0.3 O2 (NCM) have been pursued as potential cathode materials for EV and HEV applications, because of their high energy density (~200 mAh/g) and lower cost. However, at elevated temperatures, the highly delithiated (overcharged) NCA/NCM electrodes release O2 gas, preceded by the reduction of the transition metal (TM) ions and structural phase transitions (R-3m --> Fd-3m --> Fm-3m), and cause catastrophic thermal runaway reactions with the electrolyte [1, 2]. Therefore, it is critical to understand the role that the release of O2 plays in the migration of TM (Ni, Co, and Mn) cations during the various phase transition processes. Environmental transmission electron microscopy (ETEM) provides a unique platform where individual nanoparticles can be investigated for any morphological, structural or chemical changes, under external stimuli, in real-time. Furthermore, the aberration-corrected ETEM with differential pumping apparatus allows high spatial resolution of
12:15 PM - EE4.10.10
The Importance of Solid Electrolyte Interphase (SEI) Formation for Long Cycle Stability Full-Cell Na-Ion Battery
Xiaolin Li 1,Pengfei Yan 1,Mark Engelhard 1,Chongmin Wang 1,Daiwon Choi 1,Jun Liu 1,Vincent Sprenkle 1
1 Pacific Northwest National Lab Richland United States,
Show AbstractNa-ion battery as alternative high-efficiency and low-cost energy storage device to Li-ion battery has attracted wide interest for electrical grids, vehicles and portable electronics applications. However, demonstration of a full-cell battery with high energy (>300 Wh/kg-cathode) and long cycle life (>1000 cycles) remains a significant challenge. Here, we investigated the role of solid electrolyte interphase (SEI) formation on both cathode and anode materials and provided a potential pathway to achieve long term stability for Na-ion battery full-cells. Pre-cycle of Na0.44MnO2 cathode and hard carbon anode will lead to pre-formation of SEI on electrodes surface and hence mitigated electrolyte consumption in full-cells. The Na0.44MnO2-hard carbon full-cell with matched cathode-to-anode capacity and pre-formed SEI can deliver specific capacity of ~116 and 108 mAh/g based on Na0.44MnO2 at 1C and 2C rate (1C=120 mA/g). The corresponding specific energy is ~313 and ~286 Wh/kg, respectively. Superb cycling stability with capacity retention of ~77% and energy retention of ~74% over 2000 cycles at 2C rate was demonstrated.
12:30 PM - EE4.10.11
Operando X-Ray Investigations of Self-Healing Silicon Anodes in Lithium-Ion Batteries
Sean Andrews 2,Zheng Chen 1,Jeffrey Lopez 1,Michael Toney 2,Zhenan Bao 1
1 Chemical Engineering Stanford University Stanford United States,2 SSRL SLAC National Accelerator Lab Menlo Park United States,1 Chemical Engineering Stanford University Stanford United States2 SSRL SLAC National Accelerator Lab Menlo Park United States
Show AbstractHigh capacity anode material candidates for lithium-ion batteries, such as silicon, germanium, and tin, experience extreme and unavoidable expansion and contraction during the lithiation and delithiation processes. These volumetric changes lead to rapid morphology deterioration of the electrode materials (cracks, electrical isolation of particles, pulverization, etc), which severely limits the battery lifetime to a few charge-discharge cycles. While the use of nanoparticles or complex structures can avoid this volumetric deterioration, these strategies tend to be expensive and do not easily handle larger mass loadings. Instead of avoiding deterioration, lessons from nature suggest that utilizing self-healing functionality may provide the answer to stable battery operation. The idea of self-healing has recently been demonstrated to improve anodic cycling performance of low cost micron-sized silicon particles (SiMPs) via utilization of a Self-Healing Polymer (SHP), in lieu of traditionally used binders. This novel concept has shown to greatly increase the cycle life, even for thick electrodes, as compared to traditional polymer binders.
While the first iteration of the SHP-binder is a great step towards next-generation LIB, the function of self-healing within the battery anode under operation is not well understood. To this end, transmission x-ray microscopy (TXM) and small angle x-ray scattering (SAXS) were used to monitor operando structural changes of the SiMPs within the SHP-SiMPs anodes. Tracking of contrast and structural changes of individual SiMPs in images at various points along the first two charge/discharge cycles give key insights into the effects of the SHP binder. Furthermore, particle size changes in thick SHP-SiMPs anodes layers indicate maintained particle electrical connectivity during cycling. The data gathered from this study aids our mechanistic understanding of the self-healing process that occurs within the operating battery and provides certain design rules for enhanced performance in next-generation Si-based anode composites.
12:45 PM - EE4.10.12
Li-Ion Transport in Transmission Electron Microscope
Nan Jiang 1
1 Arizona State Univ Tempe United States,
Show AbstractFor portable and mobile electronic devices, improvements in current lithium ion batteries (LIBs) are urgently needed. We believe that in-operando observation at near-atomic spatial resolution, combined with millivolt electron energy-resolution spectroscopy (EELS) at the same spatial resolution, will prove the most powerful tool for understanding the atomic processes involved, and so suggest the means to improve performance. Therefore, we introduce a novel technique to study atom transport driven by local electric field in TEM/STEM and thus to simulate in situ atomic transport in a battery operation with sub-nm spatial resolution. The driving force for Li ion transport is the local electric field, which is induced by accumulated positive charges during exposure to the electron beam in the insulating electrolyte or anode materials [1]. These positive charges are produced by the ejection of secondary electrons (SEs) and Auger electrons due to excitations and ionizations by the incident electrons. The main advantage of this method is its inexpensive and easy setup for experiment. It is different from the method used in the conventional in situ TEM/STEM studies of battery materials, in which the driving forces are externally applied electric fields by the power supply, and thus a specialized TEM holder is required to set up a LIB cell.
The method has been applied to investigate the Li transport and lithiation of amorphous C [2] and Li ion migration in Li4Ti5O12 anode under local electric field [3]. In the former, it was discovered that only a small portion of Li reacts with C forming Li-C compounds, while the majority of the Li is in form of “free” Li+ ion state. Spinel Li4Ti5O12 has also been attractive for its usage as the anode in LIB due to its excellent cycling stability and accommodation of Li. However, under strong local electric fields, the original tetrahedral-coordinated Li ions migrate to the octahedral sites, resulting phase transformation from spinel to a random rocksalt structure. This transition is irreversible. In both cases, it demonstrated that the Li transport and migration can be achieved under electron irradiation alone, without an external power supply. Therefore, this work also raises reasonable doubts about operating a full LIB cell under electron beam illumination in TEM/STEM.
[1] N. Jiang, Report on Progress in Physics (2015), in press.
[2] N. Jiang, J. Mater. Res. 30, 424 (2015).
[3] D. Su, F. Wang, C. Ma, and Jiang, N., Nano Energy 2, 343 (2013).
EE4.11: Solid-State Batteries
Session Chairs
Friday PM, April 01, 2016
PCC West, 100 Level, Room 103 AB
2:30 PM - EE4.11.01
Stable Barrier Coatings for All Solid-State Batteries
Lincoln Miara 1,William Richards 2,Yan Wang 2,Jae Kim 2,Gerbrand Ceder 4
1 Samsung Advanced Institute of Technology - USA Cambridge United States,2 Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge United States2 Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge United States,3 Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley United States,4 Department of Materials Science and Engineering University of California, Berkeley Berkeley United States
Show AbstractThe safety problems associated with conventional lithium ion batteries are largely related to electrolyte decomposition. One approach to address this problem is to replace the current liquid electrolyte with inorganic solids. A solid electrolyte must have high lithium ion conductivity, as well as chemical and electrochemical compatibility with the electrodes; however, decades of research have yet to discover a commercially viable replacement for organic liquid electrolytes. A promising technique is to use a combination of solid materials instead of a single material. Paired with a highly conductive separator, a bi- or tri-layer electrolyte offers a method to meet the intense demands on a solid electrolyte. Here we report our results on a new class of materials: doped Li9S3N as an anode protective layer. [1] We combine first principles calculations and experimental confirmation to support the use of this material in all solid state batteries. Further, we demonstrate a technique for identifying interphase layers when pairing the garnet electrolyte with several common cathode materials.[2]
[1] L. J. Miara, N. Suzuki, W. D. Richards, Y. Wang, J. C. Kim, and G. Ceder, “Li-ion conductivity in Li9S3N,” J. Mater. Chem. A, vol. 3, no. 40, pp. 20338–20344, Oct. 2015.
[2] L. J. Miara, W. D. Richards, Y. E. Wang, and G. Ceder, “First-Principles Studies on Cation Dopants and Electrolyte|Cathode Interphases for Lithium Garnets,” Chem. Mater., vol. 27, no. 11, pp. 4040–4047, Jun. 2015.
2:45 PM - EE4.11.02
All-Solid-State Lithium-Sulfur Batteries
Alice Cassel 3,Virginie Viallet 3,Mathieu Morcrette 3
1 Laboratoire de Réactivité et Chimie des Solides - CNRS UMR7314 - Université de Picardie Jules Verne Amiens France,2 Réseau sur le Stockage Electrochimique de l’Energie (RS2E), FR CNRS 3459 Amiens France,3 ALISTORE-ERI, FR CNRS 3104 Amiens France,
Show AbstractCurrently, lithium-ion batteries incorporated in electric vehicles do not allow to store enough energy to ensure sufficient autonomy. Therefore, it’s necessary to develop new generations of batteries with higher energy density. Among battery technologies, the lithium-sulfur system (Li-S) is considered to be one of the most promising solutions due to a theoretical energy density of 2500 Wh/kg. However, its lifetime remains limited due to the polysulfide shuttle effect, induced by the use of liquid electrolyte. Indeed, many polysulfides (noted Li2Sx 1 ≤ x ≤ 8), formed during the sulfur reduction to Li2S, dissolve in liquid electrolyte and diffuse between both electrodes, leading to a rapid decrease of electrochemical performances.
All-solid-state Li-S batteries were studied in order to bypass the limitations of liquid electrolyte. The electrode is a composite material with sulfur (S8) as active material, argyrodite (Li6PS5Cl) as solid electrolyte for ionic conduction and Ketjen Black (KB) as additive conductor for electronic percolation. The liquid electrolyte between both electrodes is replaced by the solid electrolyte used in the composite electrode and metallic lithium is used as negative electrode.
The positive electrode was prepared by mixing and ball-milling at 370 rpm for 5h using a high-energy planetary ball mill, S8, Li6PS5Cl and KB with a weight ratio of 25:50:25. The battery displays a reversible capacity of 1565 mAh/g after 10 cycles at a current density of 134 μA/cm2 (corresponding to a rate of C/10) with an initial discharge capacity of 1230 mAh/g and an extra capacity of around 335 mAh/g, observed for the first time and currently under studies.
At high current density, with lithium negative electrode, we observed strange potential decreases that can be related to short circuit phenomena. One explanation for short circuit phenomena can be the formation of lithium dendrites, although they are not supposed to grow in solid electrolyte. The presence of dendrites will be evidenced by solid state NMR. Using alternative Li-In electrode, this phenomenon was totally suppressed. In this presentation, we will then show our best optimized solid state batteries using a Li-Indium electrode with a good capacity (1660 mAh/g after 10 cycles at C/10), a good coulombic efficiency and a reasonable polarization for a solid-state battery and at room temperature. Perspectives in term of energy density and industrialization (upscale of the lithium ion conductors) will be presented.
3:00 PM - EE4.11.03
All-Solid-State Lithium-Ion Thin-Film Batteries Using a New Lithiated Titanium Oxysulfide Cathode: High Performance and Reversibility
Frederic Le Cras 1,Brigitte Pecquenard 2,Vincent Dubois 3
1 CEA LETI Grenoble France,2 ICMCB Pessac France2 ICMCB Pessac France,3 STMicroelectronics Tours France
Show AbstractThe significant growth of both the number and the kinds of portable electronic systems, generally battery-powered has triggered the race for the development of high-performance microprocessors and systems on chips using low power consumption integrated circuits. As a consequence, the energy supply of such optimized components can also be ensured today by miniaturized power sources such as Li microbatteries. The latter have the advantage of being manufactured by vacuum deposition process also widely used in the microelectronics industry [1]. Nevertheless to be considered as an electronic components, the microbattery need to sustain temperature higher than 230°C for the reflow soldering to attach the component to the PCB . As Li metal anode melts at 181°C, Li microbatteries are not tolerant to such high temperature. For this reason we have manufactured Li-ion all-solid-state thin films batteries based on Si at the negative electrode and a new lithiated titanium oxysulfide as a cathode [2]. This new thin film material was prepared by sputtering from a home-made LiTiS2 target. The resulting films are quite dense, amorphous with a composition close to Li1.2TiIVO0.5SII2.1. A full electrochemical delithiation of this electrode corresponding to a capacity of 64 µAh.cm-2.µm-1 was achieved in all-solid-state cells. As Ti4+ cannot be involved in the oxidation process, only sulfide species are oxidized during charge up to 2.9 V/Li+/Li forming S22- disulfide anions. The subsequent lithiation and delithiation curves showing no capacity loss, demonstrate the perfect reversibility of the electrochemical processes. Actually, when cycled in the 3.2-1.5 V voltage window versus a lithium anode, extra lithium can be inserted in the material below 2V and titanium is partly reduced. The increase of the current density from 2 to 130 µA.cm-2 (i.e from C/50 to 2C rates) induces only a slight capacity decrease, mainly due to an increase of the polarization near the end of charge. Besides, the capacity retention is found to be excellent during extended cycling with a capacity fading lower than -0.01 % per cycle and a mean coulombic efficiency close to 100%. Excellent electrochemical performances in terms of capacity value and cycling stability were also obtained in all-solid state Li-ion cells with Si as a negative electrode. After three successive solder-reflow processes (thermal treatment at 260°C), the capacity, the cycle life as well as the voltage profile remained unchanged. Finally, Li1.2TiO0.5S2.1 is confirmed as a new interesting lithiated positive material for thin film lithium and lithium-ion microbatteries. Moreover, as its synthesis does not require any thermal treatment (contrary to the well-known LiCoO2), is well-adapted to thermally sensitive substrates such as flexible polymers foils.
References:
[1] B. Pecquenard, F. Le Cras et al., J. Power Sources, 196 (2011) 10289
[2] F. Le Cras, B. Pecquenard et al., Adv. Energy Mater., 5 (2015) 1501061
3:15 PM - EE4.11.04
Fe2(MoO4)3 as an Alternative Positive Electrode for Li or Na Thin-Film Batteries
Vincent Pele 2,Brigitte Pecquenard 1,Frederic Le Cras 2,Stephane Cotte 1
1 ICMCB Pessac France,2 LETI CEA Grenoble France,1 ICMCB Pessac France2 LETI CEA Grenoble France
Show AbstractThe significant growth of portable electronics, generally battery-powered, has triggered the race for the development of high-performances microprocessors, Systems-on-a-Chip or DRAM, using low power consumption integrated circuits. As a consequence, the energy supply of such optimized components can be operated today also by miniaturized power sources such as microbatteries. Up to now, Li/LiPON/LiCoO2, is the most used system, supplying a 4.2 V voltage. Nevertheless, their 4V operating voltage is not convenient for all applications, which may require often significantly lower ones. The replacement of Li/gamma-MnO2 primary batteries by thin films batteries in selected devices has motivated the development of specific 3V rechargeable systems [1]. Among the possible positive electrode material able to reversibly insert/deinsert Li at 3V/Li+/Li or Na at 2.7 V/Na+/Na [2], iron molybdate Fe2(MoO4)3 thin films appear as a suitable candidate as they combine the following features: ability to reversibly insert/deinsert Li or Na in bulk form due to a bidimensional open framework, low cost and environmental friendliness.
In the present study, radio-frequency sputtering, which is a versatile technique and a process widely used in the microelectronic industry was used to prepare iron molybdate thin films. After an optimization of the sputtering conditions especially the power, oxygen partial pressure and the total pressure, we have focused our thorough physico-chemical and electrochemical characterizations on stoichiometric films annealed at various temperatures between 200 and 500°C. The corresponding film with a monoclinic structure was then thoroughly studied (XRD, XPS, RBS, SEM, EPMA, Raman and Auger spectroscopies). Thin films electrodes were set in coin cells with liquid electrolytes for electrochemical characterization with metallic Li or Na as a negative electrode. The voltage curves displayed a plateau with a low hysteresis and a good cycle life (with a capacity corresponding to 96 % of the theoretical capacity). When changing from Li to Na, a modification of the shape of the voltage curve highlights a modification of the intercalation mechanism, from a biphasic to a monophasic process. XPS and Mössbauer analyses were performed on the inserted phases to investigate further the reaction mechanisms. Finally, all-solid-state cells were tested with Li as a negative electrode.
References:
[1] S. Cotte, B. Pecquenard, F. Le Cras, R. Grissa, H. Martinez, L. Bourgeois, Electrochimica Acta 180 (2015) 528-534
[2] A. Nadiri, C. Delmas, R. Salmon, P. Hagenmuller, Rev. Chim. Min, 21 (1984) 537-544
3:30 PM - EE4.11.05
Materials Design Guidelines for All-Solid-State Batteries
Yan Wang 1,William Richards 1,Lincoln Miara 2,Jae Kim 3,Gerbrand Ceder 4
1 Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge United States,2 Samsung Advanced Institute of Technology-USA Cambridge United States3 Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley United States1 Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge United States,3 Materials Sciences Division Lawrence Berkeley National Laboratory Berkeley United States,4 Department of Materials Science and Engineering University of California, Berkeley Berkeley United States
Show AbstractAll-solid-state batteries with non-flammable solid-state electrolytes have significant advantages over Li-ion or Na-ion batteries with liquid electrolytes. In this talk we will present our recent advances in understanding the fundamental relationship between crystal structure and ionic transport in fast Li-ion conductors [1]. We find that the topology of the sites along the lithium hopping path, and the volume per anion, largely control the activation energy for Li motion. This topology is more favorable in compounds where the anions form a bcc lattice than in the typical close-packed fcc and hcp anion arrangements, explaining why most compounds are not fast-ion conductors. Furthermore, an accurate and efficient first-principles computational methodology has been developed to evaluate thermodynamic stability of the solid-state electrolyte against battery electrodes. These findings not only provide valuable insights towards the understanding of materials behaviors in discovered ionic conductors, but also serve as design principles for new Li and Na conducting materials and all-solid-state batteries. We will also report a few novel Li and Na ionic conductors that are predicted based on our design principles and experimentally confirmed by our collaborators.
[1] Y. Wang, et al., “Design principles for solid-state lithium superionic conductors,” Nat. Mater., 14, 1026-1031, (2015).
3:45 PM - EE4.11.06
X-Ray Nanodiffraction Study of the Delithiation Mechanism of LiFePO4 Single Particles
Brian May 1,Young-Sang Yu 2,Martin Holt 3,Fiona Strobridge 4,Clare Grey 4,Jordi Cabana-Jimenez 1
1 Chemistry University of Illinois at Chicago Chicago United States,1 Chemistry University of Illinois at Chicago Chicago United States,2 Advanced Light Source Lawrence-Berkeley National Laboratory Berkeley United States3 Center for Nanoscale Materials Argonne National Laboratory Argonne United States4 Chemistry University of Cambridge Cambridge United Kingdom
Show AbstractLithium iron phosphate (LiFePO4) has received much interest as a cathode material on account of its good reversibility, low toxicity, thermal stability, and high material abundance [1]. However, there are some key fundamental drawbacks in that it is a poor ionic and electronic conductor, which are apparent in the rate performance. Understanding the intercalation mechanism will provide insight on some of the core limitations of this material. Two-phase and solid solution mechanisms have been proposed, but details on the transformation at the single particle level remain elusive [2]. X-ray nanodiffraction measurements on single particles were carried out to produce direct observations of the electrochemical reaction at a fundamental level.
Argonne National Laboratory’s Advanced Photon Source boasts a hard x-ray nanoprobe beamline that has a very high spatial resolution of ~30nm [3]. Traditionally, this beamline has been used to study thin films. Here, its power was harnessed to observe single microcrystals in a powder sample. Two-dimensional area maps were taken of one particle each of LiFePO4, FePO4, and an intermediate average powder composition Li0.5FePO4, which contained both fluorescence and diffraction data. Combining the fluorescence and diffraction data, the phases involved in the LiFePO4-FePO4 transformation were identified within the particle from the distance between lattice planes, calculated with Bragg’s Law.
Identifying the grain boundaries between phases present in the particle highlights the effects the intercalation mechanism has on the stability of the material. In addition to phase identification, features such as strain and inhomogeneities were also identified with the utmost spatial resolution from the diffraction experiments. Visualizing these phenomena on the single particle level and how they correlate to each other sheds light upon the electrode operation and how battery failure ultimately occurs. This information may lead to advancements in this material as well as those with similar structures.
[1] Gibot P., Casas-Cabanas M., Laffont L., Levasseur S., Carlach P., Hamelet S., Tarascon J.-M., Masquelier C.,
Nat. Mater., 7 (9), 741-747, 2008.
[2] Meethong N., Shadow Huang H.-Y., Carter W. C., Chiang Y.-M., Electrochem. Solid- State Lett., 10,
A134-A138, 2007.
[3] Winarski, R.P., Holt, M.V., Rose, V., Fuesz, P., Carbaugh, D., Benson, C., Shu, D., Kline, D., Stephenson, G.B., McNulty, I., Maser, J., J. Syn. Rad., 19, 1056-1060, 2012.
4:30 PM - EE4.11.07
Tailoring Materials Chemistry for Improved Solid State Sodium-Ion Conductors
Erik Spoerke 1,Jill Wheeler 1,Leo Small 1,Jon Ihlefeld 1,Paul Clem 1,David Ingersoll 1
1 Sandia National Laboratories Albuquerque United States,
Show AbstractSolid state electrolytes are critical enabling elements of emerging electrical energy storage technologies, such as sodium-based batteries. Realizing the promise of these developing technologies, however, depends on the development of chemically and structurally robust solid state electrolytes, stable against a variety of molten, organic, and even aqueous media. Here we explore the materials chemistry of a family of NaSICON (Sodium Super Ion CONductor) ceramics with the composition Na1+xZr2P3-xSixO12 (0≤x≤2), which show excellent low temperature sodium ion conductivity. Despite the promising stability of these ceramics against materials such as molten sodium and a range of organic electrolytes, there remain potentially significant materials stability challenges to using these materials in next generation technologies that might employ, for example, aggressive aqueous media. Here we specifically discuss potential “weak links” in the NaSICON phase chemistry and ceramic composition that make it potentially susceptible to degradation both in bulk and in novel thin film morphologies. Moreover, we describe our efforts to tune these characteristics during synthesis to produce improved NaSICON stability in aggressive electrolyte environments. Advancing the development of highly conductive, chemically stable solid state ion conductors stands to open the door to a range of innovative new sodium-based energy storage technologies needed to meet the ever-growing demand for safe, reliable, and effective electrical energy storage and delivery.
Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the US Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.
4:45 PM - EE4.11.08
Science and Technology of Electrically Conductive/Corrosioin Resistant Ultrananocrystalline Diamond-Coated Natural Graphite-Copper Anode for New Long Life Lithium-Ion Battery
Yin-Wei Chen 3,Chi-Kai Lin 3,Yueh-Chieh Chu 4,Ali Abouimrane 3,Zonghai Chen 3,Yang Ren 5,Chuan-Pu Liu 6,Yonhua Tzeng 7,Orlando Auciello 2
3 Chemical Sciences and Engineering Division Argonne National Laboratory Lemont United States,4 Institute of Microelectronics, Department of Electrical Engineering National Cheng Kung University Tainan Taiwan5 4X-Ray Science Division Argonne National Laboratory Lemont United States6 Department Materials Science and Engineering National Cheng Kung University Tainan Taiwan7 Institute of Microelectronics, Department of Electrical Engineering National Cheng Kung University Tainan Taiwan1 Materials Science and Engineering University of Texas at Dallas Richardson United States,2 Bioengineering University of Texas at Dallas Richardson United States
Show AbstractAlthough Li-ion batteries (LIBs) are powering electric cars (GM’s Volt), problems still exist in terms of performance, mainly because current LIBs feature natural graphite (NG)-based anodes, which exhibit large irreversible capacity loss and short charging-discharging cycling life induced by chemical reactions between Li-ion inserted NG and organic electrolyte. This report shows that this problem is overcome by using a novel nitrogen-incorporated ultrananocrystalline diamond (N-UNCD) encapsulated NG/copper complex anodes. N-UNCD films (~5-10 nm grain size) exhibit electrically conductive grain boundaries induced by nitrogen incorporation into the boundaries, satisfying carbon sp2 dangling bonds and providing electrons for conduction. In addition, N-UNCD films provide excellent chemical inertness, electronic/lithium ionic conductivity, and excellent lithium ions permeation between the electrolyte and the N-UNCD encapsulated NG matrix of NG/Cu anodes. N-UNCD enables robust solid electrolyte interphase (SEI) formed by anode/electrolyte chemical reactions and suppresses stress induced cracks of the SEI and NG particles and the subsequent loss of anode conductivity. X-ray diffraction and chemical analysis proved the integrity of N-UNCD/NG/Cu anodes and provided understanding of the new robust anode performance to enable next generation LIBs with potentially 10x longer life and superior performance than current LIBs.
5:15 PM - EE4.11.10
A Core/Shell Structure of Amorphous/Crystalline Silicon Fabricated Using RF Sputtering as Anodes for High Performance Li-Ion Batteries
In-Kyoung Ahn 1,Ji-Hoon Lee 2,Dae-Hyun Nam 1,Ho-Young Kang 1,Young-Chang Joo 1
1 Department of Materials Science amp; Engineering Seoul National Univ Seoul Korea (the Republic of),2 Center for Energy Convergence Research Korea Institute of Science and Technology Seoul Korea (the Republic of)
Show AbstractWith growing demands for high performance rechargeable batteries, metal alloy-based anodes are receiving great attention due to their high theoretical capacity. Among them, the most promising material is referred to silicon whose theoretical capacity is 3579 mAh/g. However, poor cycling stability caused by catastrophic volume change of 400 % during de-/lithiation is the major obstacle for the practical application of Si. To overcome the issue, nanostructuring or surface modification has been suggested by previous researches. However, they reported reduction in the capacity due to the electrochemical-inactive coating material, while the capacity retention was improved. Herein, a novel surface modification method to design high performance Si-based anodes was suggested. Based on modified RF sputtering system with vibration motors held by the holder, amorphous Si (a-Si) was uniformly deposited on the nanocrystalline Si (nc-Si) powders. The newly-designed a-Si/nc-Si anodes show distinct strong points. First, a-Si has higher robustness and resistance to failure than crystalline. Furthermore, a-Si contributed to the energy storage process unlike widely used coating material, e.g., oxides.
Nc-Si powder was used as the starting material for the P doped n-type amorphous Si. The average powder size of nc-Si was approximately 50 nm. The sputtering time and power were varied from 5 min to 3 h and from 50 W to 200 W to optimize the thickness of coating layer with the fixed Ar pressure and each RF power. The particle size and surface morphology were investigated by SEM and TEM. The effect of a-Si coating was analyzed by XRD and XPS. The electrochemical performances was investigated with coin-type half cell using 1 M LiPF6 in an EC : DEC electrolyte.
We successfully controlled the thickness of a-Si layer with high uniformity according to the sputtering time and power. The existence of a-Si was verified by XRD peak compared to bare Si powder and the P atom was confirmed by XPS. Compared to bare Si, a-Si/nc-Si generally showed enhanced capacity and retention due to the modification effect. However, as the sputtering time and power exceed over the condition for critical thickness, the performance has been degraded. It can be explained by the crystallization of coated Si with increasing layer thickness. The best performance condition was obtained at 150 W, 5 min coated a-Si/nc-Si anode. It maintained superior capacity over 1500 mAh/g and C50th/C5th performance up to 75 %. A lower resistance in EIS and improved rate capability compared to bare Si have been obtained. The a-Si buffer layer dramatically managed crack formation and prevented capacity loss by adequate surface treatment. We introduced new coating method using modified RF sputter for making highly improved electrochemical performance by forming the doped layer in Si anode. It can open new synthetic route for mass production using slurry casting cell of stable Si anodes, which is simple and cost effective.
5:30 PM - EE4.11.11
Combined Physical and Chemical Immobilization of Sulfur Species Using Cellulous-Derived Nanofibers for Lithium-Sulfur Batteries
Shiqi Li 2,Guofeng Ren 1,Ying Gao 1,Zhaoyang Fan 1
1 Department of Electrical and Computer Engineering Texas Tech University Lubbock United States,2 Department of Science and Technology Chongqing Public Security Bureau Chongqing China,1 Department of Electrical and Computer Engineering Texas Tech University Lubbock United States
Show AbstractTo develop high-capacity and low-cost lithium-sulfur (Li-S) batteries, the challenging problem related to the soluble lithium polysulfides must be probably addressed, since these soluble intermediates (Li2S8-Li2S6) can easily diffuse to the negative electrode, where they are reduced to Li2S and deposit, resulting in low utilization of active materials and fast capacity fading. The strategies to solve this problem can be generally categorized as physical confinement in micropores or chemical immobilization through bonding of sulfur species in a carrier structure. Integrating physical and chemical immobilization together will be a better alternative approach without introducing extra inactive material. Herein, we report the design and characterization of a novel sulfur cathode with physical and chemical immobilization of sulfur species using microporous nitrogen-doped carbon fiber (MPNC). Cellulose aerogel was first activated to obtain mesoporous carbon nanofibers that are subsequently hydrothermally treated in aqueous ammonia for heavily nitrogen doping. The Li-S batteries based on MPNC-sulfur cathode showed high specific capacity (> 1000 mAh/g), excellent cycling and rate capability. The physical, chemical and electrochemical properties will be reported. It is concluded that the microporous architecture facilitates space confinement of sulfur species while the hetero-doped nitrogen species, with strong binding energy to polysufides, further assists their anchoring in the cathode.