11:00 AM - *EE5.7.01
Challenges in Mg Battery
John Muldoon 1,Claudiu Bucur 1
1 Toyota Research Institute of N. America Ann Arbor United States,
Show AbstractWithout a doubt the Holy Grail of battery research is the development of a post lithium ion technology. This may require a shift towards batteries containing a pure metal anode. Li metal is an attractive metal anode in part due to its high volumetric capacity (2062 mAh cm-3), a high reductive potential of -3.0 V vs. NHE and the wide availability of lithium electrolytes. However, its deposition occurs unevenly with formation of dendrites which leads to safety concerns during cycling. In contrast to lithium metal, magnesium metal deposition is not plagued by dendritic formation. Additionally, magnesium is more stable than lithium when exposed to air, more abundant in the earth crust and provides a higher volumetric capacity (3832 mAh cm-3). However, magnesium has a reductive potential of -2.36 V vs. NHE and has a unique electrochemistry which prohibited the use of magnesium analogues of lithium electrolytes. Since the oxidative stability of electrolytes governs the choice of cathodes it is of paramount importance to develop non-corrosive magnesium electrolyte with wide electrochemical windows which will permit discovery of high voltage cathodes. In this talk we will present the latest developments and future challenges which must be overcome.1,2,3,4,5,6
1. Aurbach, D., Lu, Z., Schechter, A., Gofer, Y., Gizbar, H., Turgeman, R., Cohen, Y., Moshkovich, M. and Levi, E., Nature, 2000, 407, 724-727.
2. Kim, H.S., Arthur, T.S., Allred, G.D., Zajicek, J., Newman, J.G., Rodnyansky, A.E., Oliver, A.G., Boggess, W.C. and Muldoon, J., Nat. Commun., 2011, 2, 427.
3. Muldoon, J., Bucur, C.B., Oliver, A.G., Sugimoto, T., Matsui, M., Kim, H.S., Allred, G.D., Zajicek, J. and Kotani, Y., Energy Environ. Sci., 2012, 5, 5941-5950.
4. Muldoon, J., Bucur, C.B., Oliver, A.G., Zajicek, J., Allred, G.D and Boggess, W.C. Energy Environ. Sci, 2013, 6, 482-487.
5. Muldoon, J., Bucur, C.B. and Gregory. T. Chem. Rev., 2014, 114, 11683-11720
6. Muldoon, J., Bucur, C.B. and Gregory. T. Phys. Chem. Lett., 2015, 6, 3578–3591
2:30 PM - EE5.8.01
Anode Architectures, Anode/Electrolyte Interfaces, and High Energy-Density Anodes for Rechargeable Magnesium Battery Systems
Nikhilendra Singh 1,Timothy Arthur 1,Fuminori Mizuno 1
1 Materials Research Department Toyota Research Institute of North America Ann Arbor United States,
Show AbstractMultivalent battery systems like rechargeable magnesium (Mg) batteries have recently gained more interest as candidate post-lithium (Li) battery systems, for possible applications in electric vehicles (EVs) and plug-in hybrid vehicles (PHVs). This is primarily due to concerns over the range performance of current Li battery systems, and the space requirements for future EVs and PHVs. Mg, being divalent and denser, is theoretically capable of delivering a higher volumetric energy-density (3833 mAh cm-3) than Li (2061 mAh cm-3), making it a viable battery system for addressing current range and space concerns.1-4 To date, various organohaloaluminate electrolytes and electrolytes containing the B-H family have been utilized in Mg batteries, due to the incompatibility of conventional battery electrolytes (TFSI-, ClO4-, PF6-) with Mg metal anodes.3,5 However, as recently reported, it is also possible to use conventional battery electrolytes for Mg-ion batteries, by changing the type of anode, from a Mg metal anode to a Mg-ion insertion-type anode. This change enables Mg-ion transport through the anode/electrolyte interface during the use of conventional battery electrolytes.2-4,6
Here, we report recent advancements in alternate architectures, as well as new materials for insertion-type anodes for rechargeable Mg-ion batteries. Further, we address specific studies related to the observation of the anode/electrolyte interface for Mg batteries, which have recently been studied in some detail.7,8 Results from the utilization of alternate architectures and recent fundamental analytical analyses, focused on studying and understanding the nature of the anode/electrolyte interface, will be presented and discussed.
References:
1 Mizuno F, Singh N, Arthur TS, Fanson PT, Ramanathan M, Benmayza A, Prakash J, Liu Y-S, Glans P-A, Guo J, Frontiers in Energy Research, 2014, 2, 1.
2 N. Singh, T. S. Arthur, C. Ling, M. Matsui and F. Mizuno, Chem. Commun., 2013, 49, 149.
3 Muldoon J, Bucur CB, Gregory T, Chemical Reviews 2014, 114, 11683.
4 T. S. Arthur, N. Singh and M. Matsui, Electrochem. Commun., 2012, 16, 103.
5 Mohtadi R, Matsui M, Arthur TS, Hwang S-J, Angewandte Chemie International Edition 2012, 51, 1.
6 Shao Y, Gu M, Li X, Nie Z, Zuo P, Li G, Liu T, Xiao J, Cheng Y, Wang C, Zhang J-G, Liu J, Nano Letters, 2014, 14, 255.
7 T. S. Arthur, P-A. Glans, M. Matsui, R. Zhang, B. Ma and J. Guo, Electrochem. Commun., 2012, 24, 43.
8 Benmayza A, Ramanathan M, Arthur T, Matsui M, Mizuno F, Guo J, Glans P-A, Prakash J, Journal of Physical Chemistry C, 2013, 117, 26881.
4:30 PM - EE5.8.07
Investigation of the NaxMoO2 Phase Diagram from Sodium Electrochemical (de)Intercalation
Laura Vitoux 1,Marie Guignard 1,Francois Weill 1,Matthew Suchomel 2,Jacques Darriet 1,Claude Delmas 1
1 CNRS, Univ. Bordeaux, ICMCB, UPR 9048 Pessac France,2 Argonne National Laboratory, Advanced Photon Source Lemont United States
Show AbstractResearch on sodium layered oxides NaxMO2 (M: 3d or 4d transition metal, x: sodium content) as positive electrode in sodium ion batteries have regained interest for stationary energy storage applications. Furthermore, due to their structure, in which sodium occupy interstitial sites (octahedral or prismatic) between [MO2] slabs constituted of MoO6 edge-sharing octahedra, sodium layered oxides can exhibit original physical properties depending on their chemical composition (nature of the transition metal and sodium content).
This work focus on NaxMoO2 layered oxides, which have been the subject of only a few publications in the 1980’s concerning Na2/3MoO2 [1-4], and Na0.5MoO2 [5]. The only electrochemical investigation [4], shows a reversible sodium intercalation in NaxMoO2 for 0.28
4:45 PM - EE5.8.08
Sodium Intercalation Mechanisms into Corrugated Titanate Structures for Na-Ion Batteries
Isaac Markus 2,Mona Shirpour 2,Simon Engelke 2,Siafung Dang 3,Marco Prill 3,Robert Spatschek 3,Mark Asta 1,Marca Doeff 2
1 Material Science and Engineering UC Berkeley Berkeley United States,2 Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley United States,2 Environmental Energy Technologies Division Lawrence Berkeley National Laboratory Berkeley United States3 IEK2 Forschungzentrum Jülich Julich Germany1 Material Science and Engineering UC Berkeley Berkeley United States
Show AbstractSodium ion batteries (SIBs) are one of the most promising technologies for grid storage due to the large abundance of sodium in the earth’s crust. Grid scale storage must not only be available at a low cost but must also be based on materials that are abundant enough to cover the scale of future energy consumption. SIBs have the additional advantage that they can utilize many of the manufacturing and processing techniques used by current lithium ion batteries. However, SIBs still face challenges related to energy density given that graphite is not able to intercalate high amounts of sodium. As an alternative, sodium titanates are attractive anode materials for SIBs due to their rich range of crystal structures that can reversibly intercalate sodium ions.
In this work we investigated two types of titanates that have been recently synthesized and tested. The first is based on Na1+xTi3O6(OH)×2H2O, known as sodium nonatitanate1, and the second is based on the lepidocrocite structures, Na0.8Ti1.73Li0.27O4 and Na0.8Ti1.4Mg0.6O42. Using density functional theory (DFT) we computed the structural changes during sodiation, and calculated voltage profiles for the different materials. We also calculated changes to the sodium diffusion energy barriers at different sodium concentrations. Structural results indicate that sodium intercalation is a site-limited process in both sets of titanates, with energy barriers increasing during sodiation.
Experiments on the phase stability of these compounds are underway employing coulometric titration and differential scanning calorimetry. Because Na2Ti3O7 has been shown to undergo phase relaxation with increasing sodium content3, we seek to understand if other titanates are also susceptible to phase changes during sodiation. Thermal stability results indicate that for both sets of materials the pristine and sodiated structures are stable up to at least 500o C. Current efforts are focused on detecting if the materials undergo phase relaxations at discharge conditions.
References:
1. Shirpour M., Cabana J., Doeff M. “New materials based on a layered sodium titanate for dual electrochemical Na and Li intercalation systems”, Energy Environ. Sci., 6, 2538 (2013).
2. Shirpour M., Cabana J., Doeff M. “Lepidocrocite-type Layered Titanate Structures: New Lithium and Sodium Ion Intercalation Anode Materials.” Chemistry of Materials 2014 26 (8), 2502-2512.
3. Xu J., Ma C., Balasubramanian M., Meng Y.S. “ Understanding Na2Ti3O7 as an ultra-low voltage anode material for a Na-ion battery.” Chem. Commun. 2014, 50, 12564-12567.
EE5.9: Poster Session II: Next-Generation Supercapacitor Materials and Devices
Session Chairs
Francois Beguin
Bruce Dunn
Friday AM, April 01, 2016
Sheraton, Third Level, Phoenix Ballroom
9:00 PM - EE5.9.01
Light-Weight Nitrogen-Doped Hierarchically Porous Carbon Foam for Energy Storage Devices
Jizhang Chen 1,Ni Zhao 1,Ching-Ping Wong 2
1 Department of Electronic Engineering The Chinese University of Hong Kong Shatin, New Territories Hong Kong,1 Department of Electronic Engineering The Chinese University of Hong Kong Shatin, New Territories Hong Kong,2 School of Materials Science and Engineering Georgia Institute of Technology Atlanta United States
Show AbstractFree-standing three dimensional (3D) carbonaceous materials have emerged as a promising type of materials, owing to their advantages such as self-support, great flexibility and compressibility, high electronic and thermal conductivities, high chemical stability, and large amount of interconnected macropores. These materials have shown attracting performances for a variety of applications, such as electrochemical electrodes (e.g. for supercapacitors, batteries, fuel cells, and solar cells), absorbers, and matrixes for sensors and thermal energy storage. Current synthesis methods for free-standing 3-D carbon are either time-consuming and complicated or uncontrollable. In this study, we address this problem through developing a facile, scalable, and cost-effective strategy to fabricate hierarchically porous carbon foam (HP-CF) by directly annealing home-made melamine foam. The HP-CF serves as an excellent material for supercapacitors owning to its multiscale, interconnected porous morphology as well as the proper density that ensures not only a high gravimetric capacitance but also a high volumetric capacitance. Moreover, the HP-CF can be used as the current collector and mechanical matrix to support pseudocapacitive materials, so that asymmetric supercapacitors (ASC) can be assembled. In the ASCs, the 3-D interconnected hierarchically porous architecture allows for rapid and efficient ionic transport, while the continuous carbon matrix provides sufficient transport routes for electrons. As a result, the obtained ASC devices exhibit both high energy and high power. Importantly, the HP-CF is much lighter and more flexible than conventional Ni foams. All these characteristics make the HP-CF an ideal material for constructing next-generation lightweight and flexible energy storage devices.
9:00 PM - EE5.9.02
Novel Carbon Nanoscale Architectures for Supercapcitors
Guanhua Zhang 2,Huigao Duan 2,Jingyue Liu 1,Wen Zhang 1
1 Departments of Physics Arizona State University Tempe United States,2 School of Physics and Electronics Hunan University Changsha China,2 School of Physics and Electronics Hunan University Changsha China1 Departments of Physics Arizona State University Tempe United States
Show AbstractThe fast-growing market for portable electronic devices and the development of hybrid electric vehicles leads to urgent demand for high performance energy storage systems. Supercapacitors have received considerable attention because of their high power density, fast recharge capability and long cycle life [1-2] Hierarchical carbon nanoarchitectures are strongly desirable for constructing advanced supercapacitors due to their high capacitance and good rate capability. The processes of fabricating such structures, however, are complicated, expensive, and time-consuming. We recently developed a novel synthesis approach to produce three-dimensionally patterned growth of hollow carbon nanotube arrays (CNTAs) on flexible cloth consisting of carbon fibers (CFs). The facile synthesis protocol is repeatable, scalable and easy to process. The CNTAs@CFs were directly used as integrated electrodes for supercapacitors and exhibited a high specific capacitance of 200 F/g at 20 A/g in 6 M KOH aqueous solution in three-electrode mode, and an excellent cycling ability with a 98% of the initial capacitance remained after 4000 cycles. Moreover, the capacitance still maintained a value of 182 F/g even when the current density increased to 40 A/g. These excellent electrochemical performances were ascribed to the novel structure of the porous vertical CNTAs which provide enhanced electronic and ionic transport. The CNTAs@CFs electrodes without the use of any auxiliary materials are expected to open up new opportunities for carbon-based materials to power flexible electronic devices. The design strategy, the synthesis processes and the electrochemical properties of the CNTAs@CFs will be discussed [3].
References
[1] Simon, Patrice, and Yury Gogotsi. Materials for electrochemical capacitors. Nature materials 7 (2008): 845-854.
[2] Pech, David, et al. Ultrahigh-power micrometre-sized supercapacitors based on onion-like carbon. Nature nanotechnology 5 (2010): 651-654.
[3] This research was funded by the College of Liberal Arts and Sciences of Arizona State University. G. Zhang acknowledges the financial support from the China Scholarship Council (CSC). The authors gratefully acknowledge the use of facilities within the LeRoy Eyring Center for Solid State Science at Arizona State University.
9:00 PM - EE5.9.03
From Lignin to a Nanoporous Carbon: How the Synthesis Steps Affect the Final Texture/Structure and the Electrochemical Properties
Adriana Navarro-Suarez 1,Damien Saurel 1,Javier Carretero-Gonzalez 2,Teofilo Rojo 3
1 CIC energiGUNE Minano Menor Spain,2 Faculty of Chemistry Warsaw University of Technology Warsaw Poland1 CIC energiGUNE Minano Menor Spain,3 Inorganic Chemistry Department University of the Basque Country Bilbao Spain
Show AbstractBatteries and supercapacitors, are of crucial importance for advanced and highly efficient energy storage and management, their complementary qualities might be used in hybrid systems which made the optimization of both materials of utmost importance. [1] In electrical double-layer capacitors (EDLCs), porous carbon is the most used electrode material because of its relatively low cost, high surface area and availability. Control of the textural (average pore size and surface area) and structural (graphitization, defects, etc.) properties of the carbon, has proven to be of great importance. The former, because only solvated or partially solvated ionic species that are smaller than the pores can be absorbed, even though a large porosity would imply low volumetric density and therefore low volumetric power and energy. While the latter, on the grounds that an increase in the crystal size of ordered regions in amorphous carbons has proven to be detrimental to the capacitance. [2, 3]
Nanoporous carbons with narrow and tunable pore size (~ 1 nm) and surface area (800-1600 m2/g) have been produced by chemical activation of lignin, an industrial by-product. The influence of carbonization/activation temperatures and activating agent ratio on the final textural and structural properties were evaluated. On one hand, Small Angle X-ray Scattering revealed the presence of an internal porosity in the carbonized samples that affected the final porosity on the activated ones as shown also by adsorption/desorption of N2 gas at 77 K. On the other hand, Raman Spectroscopy and Electronic Microscopy showed the effect of the KOH/Carbon on the formation of ordered regions embedded in the amorphous carbon.
Cyclic voltammetry studies, charge/discharge galvanostatic measurements and impedance experiments allowed determining the carbon with the most adapted pore size to each electrolyte as well as their effect on its capacitive properties in symmetric double-layer capacitors. Capacitances up to 200 F/g and 100 F/g in aqueous and organic electrolytes respectively were achieved. Ageing experiments were developed by using floating tests in aqueous electrolytes exhibiting an increase in the capacitance of 17% after 140 hours.
References
[1] F. Béguin, V. Presser, A. Balducci and E. Frackowiak, Adv. Mater., 2014, 26, 2219-2251.
[2] M. Noked, A. Soffer and D. Aurbach, J. Solid State Electrochem., 2011, 15(7), 1563-1578.
[3] A.M. Navarro-Suárez, J. Carretero-González, V. Roddatis, E. Goikolea, J. Ségalini, E. Redondo, T. Rojo and R. Mysyk, RSC Adv., 2014, 4, 48336-48343.
9:00 PM - EE5.9.04
Zeolite-Templated Carbons in Alkaline Electrolyte as Electric Double Layer Capacitors
Chenchen Hu 2,Alexandre Magasinski 1,Gleb Yushin 1
1 School of Materials Science and Engineering Georgia Institute of Technology Atlanta United States,2 School of Materials Science and Engineering Huazhong University of Science and Technology Wuhan China,1 School of Materials Science and Engineering Georgia Institute of Technology Atlanta United States
Show AbstractElectrochemical double layer capacitors (EDLCs) have emerged as attractive energy storage devices due to their high power density and long cycle life.1 The energy is stored at the interface of electrode/electrolyte through reversible ion adsorption/desorption on high surface area carbons. Zeolite template carbons (ZTCs) first invented by Kyotani et al. 2 are promising material for both fundamental studies and practical applications of EDLCs due to their highly-ordered and well-defined micropores and large specific surface areas (SSA).3, 4 In this study, ZTCs were synthesized through a low pressure chemical vapor deposition (LPCVD) of carbon on the internal surface of a sacrificial NaY zeolite template. Optimized parameters of preparing ZTCs were systematically studied, and symmetric capacitors were assembled and tested in the series alkaline electrolyte.
Electrochemical performance of ZTCs was studied by cyclic voltammetry (CV), charge-discharge (C-D) and electrochemical impedance spectroscopy (EIS) tests in LiOH, NaOH, KOH and CsOH electrolyte solutions. The impacts of the size of the cation and solvation shell as well as its solvation energy have been systematically investigated. This presentation will discuss the substantial impacts of both the cation properties and molarity of electrolytes on their electrochemical performance in microporous carbons and will reveal the complex relationships between the size of micropores, carbon surface chemistry and electrolyte composition.
References:
1 C. Merlet, B. Rotenberg, P. A. Madden, P.-L. Taberna, P. Simon, Y. Gogotsi and M. Salanne, On the molecular origin of supercapacitance in nanoporous carbon electrodes. Nat Mater, 11, 306-310, (2012).
2 T. Kyotani, Z. Ma and A. Tomita, Template synthesis of novel porous carbons using various types of zeolites. Carbon, 41, 1451-1459, (2003).
3 Y. Korenblit, A. Kajdos, W. C. West, M. C. Smart, E. J. Brandon, A. Kvit, J. Jagiello and G. Yushin, In Situ Studies of Ion Transport in Microporous Supercapacitor Electrodes at Ultralow Temperatures. Advanced Functional Materials, 22, 1655-1662, (2012).
4 A. Kajdos, A. Kvit, F. Jones, J. Jagiello and G. Yushin, Tailoring the Pore Alignment for Rapid Ion Transport in Microporous Carbons. Journal of the American Chemical Society, 132, 3252-3253, (2010).
9:00 PM - EE5.9.05
Polyaniline-Carbon Nanotube Composite for High Performance Pseudocapacitive Desalination
Jim Benson 1,Aaron Ranallo 1,Mark Schauer 2,Gleb Yushin 1
1 Georgia Inst of Technology Atlanta United States,2 Nanocomp Technologies Inc. Concord United States
Show AbstractCapacitive deionization (CDI) is a research field which has been gaining more interest as water scarcity and drought continue to worsen in areas throughout the world. Pseudocapacitive deionization is a subset of CDI which has shown a great promise due to high salt absorption capacities which exceed the capabilities of high surface area carbons alone and in conjunction with ion exchange membranes. Conductive polymers like polyaniline have been of interest in CDI for years due to its high conductivity, good environmental stability, tailorable nanostructure, and mechanical properties. Compared to other supercapacitor active materials PANI is unique in that the ion exchange process by which the polymer equilibrates with acid solutions also imposes the anion into the polymer. This has been the basis for the use of PANI as an anion exchange polymer for mixtures of halide ions such as those found in salt water and can be used for desalination applications using CDI.
Most synthesis using in situ polymerization result in poor adhesion and poor cyclability. Electrodeposition provides a better coverage and higher material utilization and doesn’t need a binder but requires a high quality substrate with good mechanical support. We were able to achieve uniform nanometer scale coatings through the bulk of these fabrics while maintaining high polymer mass loading by using a pulsed current electrodeposition method.
A CNT-based fabric was produced using a commercial-scale continuous chemical vapor deposition process that allows rapid manufacturing of high-strength CNT sheets with tunable mechanical properties. In addition to providing a platform for achieving multifunctionality, these CNT substrates also allow the elimination of non-electroactive materials such as binders and heavy foil current collectors which further increase the desalting efficiency.
When tested for CDI applications in synthetic NaCl solution and brackish groundwater samples, the composites showed rapid ion adsorption and high specific and volumetric capacitances up to 240 F●g-1 (~310 F●cm-3) in salt solutions exceeding that of state of the art activated carbon electrodes. In contrast to other PANI-containing composites, the conformal coating and CNT structural characteristics and electrical conductivity allow for a stable performance during more than 20,000 galvanostatic cycles at high current densities and in real ground water samples. The effects of varying the mass loading were also studied. Additionally, constant voltage salt adsorption experiments were performed at different adsorption times (5-30min) and voltage steps (0.6-1.2V) in beaker cell experiments. Finally salt adsorption studies will be discussed using continuous flow cell experiments in conjunction with real time solution conductivity measurements.
9:00 PM - EE5.9.06
Mesoporous Hollow Carbon Nanofibers for Supercapacitors
Yian Song 1,Guanhua Zhang 1,Jingyue Liu 1
1 Arizona State University Tempe United States,
Show AbstractSupercapacitors, due to their high power density and the ability to bridge the gap between conventional capacitors and batteries, have recently attracted much attention [1]. The goal of developing supercapacitors is to increase their energy density, reduce their charge time, and extend their lifetime. It is desirable to design and synthesize porous hollow carbon nanostructures with large specific surface area and appropriate pore sizes for transport of ions or ion complexes while maintaining excellent electrical conductivity. The use of hollow nanostructures is presumed to provide “ion buffering” reservoirs which can expedite the charge and discharge processes [2]. Excellent electrical conductivity requires highly graphitized carbon and conducting channels for electron transport. High-surface area and large pores, however, may decrease the electrical conductivity of the system. Therefore, there may exist delicate structural balances to optimize both the electrical and ionic conductivity for better supercapacitor systems. We have used ZnO nanowires as sacrificial templates to synthesize porous hollow carbon nanofibers. Since the diameter/length of the ZnO nanowires can be tuned, the effects of the inner diameter/length of the carbon nanofibers on the performances of the supercapacitors can be evaluated. Furthermore, because of the catalytic properties of the ZnO nanowires both ethanol decomposition and steam reforming reaction occur on the ZnO surface, leaving a layer of carbonaceous species uniformly coated on the ZnO nanowires. Thermal treatment to remove the ZnO nanowires results in porous hollow carbon nanofibers and by controlling the thickness of the coating layer porous carbon nanofibers with controllable wall thicknesses can be synthesized. Initial results demonstrated that high surface area (>1100 m2/g) and large specific capacitance (>220 F/g at 1A/g current density) could be obtained [3].
References
[1] Simon, P.; Gogotsi, Y. Nat Mater 2008, 7, 845-854.
[2] You, B.; Yang, J.; Sun, Y. Q.; Su, Q. D. Chemical Communications 2011, 47, 12364-12366.
[3] The authors acknowledge funding by the College of the Liberal Arts and Science of Arizona State University and the use of facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University. We appreciate the assistance of Mr. Daniel Mieritz and Dr. Don Seo for surface area measurement.
9:00 PM - EE5.9.07
Large-Scale Fabrication of Three-Dimensional Carbon Based Materials for Supercapacitors
Minghao Yu 1,Yinxiang Zeng 1,Yexiang Tong 1,Xihong Lu 1
1 Sun Yat-Sen Univ Guangzhou China,
Show AbstractThree-dimensional graphene based materials (3DGs) are emerging as a new class of electrode materials for Supercapacitors because of its unique structure and fascinating properties.However, most of the developed approaches for preparing 3DGs require high production cost, high temperature, and/or complicated manipulation and instrumentations, which are still not satisfactory for large-scale production of 3DGs in low cost. Recently, we demonstrated for the first time that the use of commercial graphite paper (GP) to massively prepare macroscopically porous 3DGs by combining the modified Hummer's method with a freezing technique. Compared with recently reported strategies for producing 3D graphene, the present method has significant advantages of simpleness, time- and energy-saving, low cost and suitable for massive production. The as-prepared 3DGs that consisted of well exfoliated, high-quality reduced graphene oxide (RGO) exhibited meso-porous structure and superior conductivity. When used as scaffold for PANI, the PANI/3DGs composite electrode yielded a highest specific capacitance of 596.1 F g−1 at a current of 2 mA, which is considerably higher than the values in recent reports for PANI electrodes. In addition, we also developed a new one-step electrochemical activation strategy to distinctly boost the capacitive properties of the commercial carbon cloth (CC) under mild conditions and their implementation as high-performance anodes for asymmetric supercapacitors (ASCs). The electrochemically activated CC (EACC) electrode reached an impressive areal capacitance of 756 mF cm−2 at a high current density of 6 mA cm−2 with predominant cycling stability. Moreover, a flexible ASC device with a remarkable energy density of 1.5 mWh cm−3 and stable working voltage of 2 V was achieved by using the EACC electrode as anode and a MnO2@TiN electrode as cathode. Additionally, this fabricated MnO2@TiN//EACC ASC device also has excellent long-term durability without any decay of capacitive performance after 70 000 cycles.
9:00 PM - EE5.9.08
Graphene and Poly (3,4-ethylenedioxythiophene) (PEDOT) Based Hybrid Supercapacitors with Ionic Liquid Gel Electrolyte in Solid-State Design and their Electrochemical Performance in Storage of Solar Photovoltaic Generated Electricity
Amr Obeidat 2,Alok Rastogi 2
1 Electrical and Computer Engineering Binghamton University, SUNY, Binghamton Binghamton United States,2 Center for Autonomous Solar Power (CASP) Binghamton University, SUNY, Binghamton Binghamton United States,
Show AbstractSupercapacitors with high specific power, fast charging rates and long cycle life are now well recognized as potent energy/power storage devices. Energy storage in one category of supercapacitors is via ion accumulation in electrified double layers and in the other via redox processes. Graphene and carbon nanotubes boost capacitive energy by large surface area and open pore structure in double layer capacitors. Redox pseudocapacitors are based on PEDOT, polyaniline or polypyrrole, conducting polymers and transition metal oxides. Extensive research is required to bridge the technology gap in attaining high energy density capability comparable to that of rechargeable batteries. In this context, hybrid supercapacitors which utilize one double layer and the other pesudocapacitive electrode function over high potentials to boost energy density based in the relation 0.5CV2. Due to instability of aqueous electrolyte at high voltages and toxicity of organic electrolytes, potential of hybrid supercapacitor has not been fully exploited.
In this work, we used ionic liquid gel polymer electrolyte having stable potential of ~3.2V to fabricate hybrid supercapacitors with nanofibrous PEDOT and graphene asymmetric electrodes. PEDOT electrode was prepared by ultra-short pulsed current electro-polymerization using LiClO4 in acetonitrile over flexible graphite sheets. Highly mesoporous graphene electrode of 600 m2g-1 surface area was formed by slurry coating using graphene platelets of thickness 8 nm and size <2 μm. Ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4) mixed with P(VdF-co-HFP) forms gel electrolyte. Sandwiched between PEDOT and graphene electrodes, it serves as both charge transfer medium and separator in a highly compact and simplified supercapacitor assembly. Electrochemical cyclic voltammetry (CV) plots over 0-2.5V are rectangular about zero current axis and by remaining undistorted at high scan 100 mV.s-1 rates asserts to highly capacitive behavior and fast redox processes comparable to that of graphene double layer electrode. High areal capacitance of 198.3 mF cm-2 (110.2 Fg-1) which scales with potential was realized. CV studies with varied PEDOT thickness led to balancing of stored charge between PEDOT and graphene and in optimized capacitance of hybrid devices. Energy and power density evaluated by systematic charge-discharge plots at different 0.1-0.5 mA.cm-2 current densities show cyclic stability and specific energy 3.7 Wh kg-1 and power 2.53 KW kg-1. With flat stackable solid-state platform, such hybrid supercapacitors were integrated at backside of solar cell module and investigation of charging of supercapacitors by solar cells provided new perspective on direct storage of solar electricity. This paper describes electrode synthesis, design and electrochemical properties of hybrid supercapacitors and energy storage performance in backing up solar cell generated electricity under various power and light levels.
9:00 PM - EE5.9.09
Reduced Graphene Oxide Hydrogel Deposited in Nickel Foam for Supercapacitor Applications: Toward High Volumetric Capacitance
Viet Hung Pham 1,James Dickerson 1
1 Brookhaven National Laboratory Upton United States,
Show AbstractSupercapacitors, a class of electrochemical energy storage devices with superior power densities and long cycling lifetimes, have attracted great attention for the last decade due to their widespread application in backup power supply systems, portable devices, power tools, and hybrid electric vehicles. Graphene is considered as an ideal supercapacitor electrode material due to its large surface area, superior electrical conductivity, good chemical stability, and high mechanical strength. The theoretical specific capacitance of graphene is as high as ~ 550 F/g. The assembly of graphene sheets into three-dimensional interconnected porous microstructures, namely graphene hydrogels, has been considered the most effective approach to utilize these materials in supercapacitors that can achieve high specific capacitances. However, graphene hydrogels typically consist of large amount of water, up to 99 wt. %, resulting in very low graphene packing density. Therefore, the usual volumetric capacitance of graphene hydrogels is very poor, limiting their practical application.
In this study, we report a scalable method to prepare graphene hydrogels with high packing densities through the electrophoretic deposition of graphene oxide onto nickel foam, followed by an electrochemical reduction. The obtained, electrochemically reduced graphene oxide hydrogels (ERGO) on nickel foam were hydraulic compressed (up to 156 MPa) to increase the packing density of ERGO from 0.0098 to 1.32 g/cm3. In a two-electrode symmetric supercapacitor test using 6M KOH electrolyte, the compressed ERGO showed excellent performance with a volumetric specific capacitance up to 176.5 F/cm3 at a current density of 1 A g−1. Further, ERGO exhibited favorable cycling stability with retentions in range of 79 - 90 % after 10,000 cycles, depending on packing density of ERGO.
9:00 PM - EE5.9.10
Cellulose Nanofibril (CNF)–Reduced Graphene Oxide (RGO)–Carbon Nanotube (CNT) Hybrid Aerogels for Highly Flexible and All-Solid-State Supercapacitors
Qifeng Zheng 1,Zhiyong Cai 2,Zhenqiang Ma 3,Shaoqin Gong 4
1 Materials Science Program Univ of Wisconsin-Madison Madison United States,2 Forest Product Lab U.S. Department of Agriculture Madison United States3 Eelectrical and Computer Engineering University of Wisconsin-Madison Madison United States1 Materials Science Program Univ of Wisconsin-Madison Madison United States,4 Biomedical Engineering University of Wisconsin-Madison Madison United States
Show AbstractThere is an ever-increasing demand for high-performance energy storage systems due to the rapidly growing market in wearable and portable electronics such as roll-up displays and electric paper. Lightweight, high power and energy density, high flexibility, and low cost, as well as environmental friendliness, are someprincipal requirements of these energy storage devices.A novel type of highly flexible and all-solid-state supercapacitor using cellulose nanofibril (CNF)–reduced graphene oxide (RGO)–carbon nanotube (CNT) hybrid aerogels as electrodes and H2SO4–poly(vinyl alcohol) gel as the electrolytewas developed andis reported here. These solid-state flexible supercapacitors were fabricated without any binders, current collectors, or electroactive additives. Due to the porous structure of the CNF/RGO/CNT aerogel electrodes, and the excellent electrolyte absorption properties of the CNFs present in the aerogel electrodes, the resulting flexible supercapacitors exhibited a specific capacitance of 252 F g-1 at a discharge current density of 0.5 A g-1, and remarkable cycle stability with more than 99.5% capacitance retained after 1000 charge–discharge cycles at a current density of 1 A g-1. Furthermore, the supercapacitors also showed extremely high areal capacitance, areal power density, and energy density, which were 216 mF cm-2, 9.5 mW cm-2, and 28.4 μWh cm-2, respectively.The study reported here provides a simple and environmentally friendly method for fabricating porous electrode materials based on an abundant and sustainable natural polymer (i.e., CNF) and carbon materials, which possess desirable electrical and mechanical properties for flexible all-solid-state supercapacitors for energy storage.
9:00 PM - EE5.9.11
Freestanding 3D Macroporous Graphene and Polyaniline Nanowire Arrays Hybrid Frameworks for High-Performance Supercapacitors
Pingping Yu 1
1 Fudan Univ Shanghai China,
Show AbstractFlexible, lightweight and wearable supercapacitors have attracted great interests in energy storage because of their potential applications in portable electronic devices, flexible displays, electronic paper and mobile phone.[1-3] The development of supercapacitors has focused on the use of graphene, due to its excellent electric and mechanical properties, chemical stability, high specific surface area up to 2675 m2 g -1, and feasibility for large-scale production.[4-5] Graphene-based nanocomposites have been achieved by incorporating guest nanoparticles onto 2D graphene sheets.[6] However, most of these structures suffer from graphene aggregation, which causes inferior ionic accessibility and thus obtains low electrochemical performance. Therefore, macroscopic graphene framework with three-dimensional interpenetrating structures can solve the issue of poor ionic and electronic transport. In our paper, freestanding three-dimensional hierarchical porous reduced graphene oxide foam (RGO-F) was first fabricated by “dipping and dry” method using nickel foam as the template. Three-dimensional (3D) RGO-F with high conductivity provides a large porosity than that of conventional graphene films. Polyaniline (PANI) nanowire arrays aligned on the foam (RGO-F/PANI) were synthesized by in situ polymerization. A symmetric supercapacitor with high energy and power densities was fabricated using RGO-F/PANI electrode. The highly flexible and mechanically foam can directly serve as an electrode with no binders and conductive additives. Owing to its well-ordered porous structure and high electrochemical performance of RGO-F/PANI composite, the symmetric device exhibits high specific capacitance (790 F g -1) and volumetric capacitance (205.4 F cm -3), showing maximum energy density and power density of 17.6 Wh kg -1 and 98 kW kg -1. Moreover, the device possesses excellent cycle life with 80% capacitance retention after 5000 cycles. Therefore, the 3D lightweight and freestanding symmetric supercapacitor is a promising candidate in the application of high-performance energy storage systems.
[1] H. Nishide, K. Oyaizu, Science 319 (2008) 737.
[2] L. Nyholm, G. Nyström, A. Mihranyan, M. Strømme, Adv. Mater. 23 (2011) 3751.
[3] X. Lu, Y. Xia, Nat. Nanotechnol. (2006) 163.
[4] A. K. Geim, Science 324 (2009) 1530.
[5] Y. Zhu, S. Murali, M. D. Stoller, K. J. Ganesh, W. Cai, P. J. Ferreira, A. Pirkle, R. M. Wallace, K. A. Cychosz, M. Thommes, D. Su, E. A. Stach, R. S. Ruoff, Science 332 (2011) 1537.
[6] G. Wang, X. Sun, F. Lu, H. Sun, M. Yu, W. Jiang, C. Liu, J. Lian, Small 8 (2012) 452.
9:00 PM - EE5.9.12
Fabricating Covalent Hybrids of Nanoscaled Cobalt and Cobalt Oxide Polymorphs on Graphene: Towards High-Performance Electrochemical Energy Storage Supercapacitors and Enzymeless Glucose Detection
Sanju Gupta 1,Sara Carrizosa 1
1 Western Kentucky University Bowling Green United States,
Show AbstractIn this work, effective strategies for the fabrication of cobalt oxide/graphene hybrid nanostructures are highlighted by focusing on the effects of their structure and morphology producing tailored interfaces on their electrochemical performance. Nanostructure engineering has been demonstrated as an effective approach to improve the electrochemical performance of electrochemical electrode materials. Employing a simple hydrothermal procedure and electrodeposition techniques followed by thermal treatment, cobalt nanoparticles (CoNP) and cobalt oxide polymorphs such as CoO and Co3O4 nanostructures were in-situ synthesized on two- and three-dimensional graphene nanosheets. The structure and morphology of the resulting various covalent graphene/cobalt hybrid composites were characterized by scanning and transmission electron microscopy, X-ray diffraction, and Raman spectroscopy. The graphene/ cobalt hybrid composites were investigated as electrochemical electrodes for asymmetric supercapacitor application and as electroanalytical platforms for enzymeless detection of glucose. We demonstrated that Co3O4/ErGO and Co3O4/multilayer graphene hybrids are capable of delivering high specific capacitance of > 600 F g-1 at a current density of 10 A g-1 is achieved when the mass ratio of Co3O4 to ErGO is equal to 80:20 as compared with other hybrids with excellent cycling stability in a voltage of 0–1.2 V. It can also detect glucose with a ultrahigh sensitivity of 3.57 mA mM-1 cm-2 and a remarkable lower detection limit of < 50 nM. We gratefully acknowledge the financial support in parts by NSF KY EPSCoR and WKU Research Foundation.
9:00 PM - EE5.9.13
Recycling Waste Si Wafer for Supercapacitor Electrodes by Conversion to Micro/Mesoporous SiC Flakes
Myeongjin Kim 1,Kiho Kim 1,Hyun Ju 1,Jooheon Kim 1
1 Chung-Ang Univ Seoul Korea (the Republic of),
Show AbstractMicro- and meso-porous SiC flakes with a high surface area of about 1376 m2g-1 were obtained by one-step carbonization of waste Si wafer without any chemical or physical activation. The micro-pores are formed by the partial evaporation of Si atoms during the carbonization process and meso-pores are derived from the combination of neighboring micro-pores. These dual pore systems can supply enhanced electric double layer capacitance by micro-pores and reduced resistant path with excellent charge propagation by meso-pores. Two-electrode supercapacitor cells constructed with this SiC yielded high electrochemical performance with aqueous and organic electrolytes. The outstanding electrochemical performance opens up new possible applications as supercapacitor electrodes based on this form of SiC.
9:00 PM - EE5.9.14
High Performance Energy Storage Material from Bio-Waste
Charith Ranaweera 1,Pawan Kahol 1,Petar Dvornic 1,Ram Gupta 1
1 Pittsburg State Univ Pittsburg United States,
Show AbstractTo meet increasing demands for energy from sources other than fossil fuels, it is a perfect time to develop sustainable and reproducible energy storage devices. Recent efforts have focused on more efficient energy storage devices including supercapacitors which have high power densities, fast charge–discharge capabilities and long life cycles. Such supercapacitors are aimed at emergency power systems, electric vehicles, and devices where high-power delivery is required, and several types of materials, such as metal oxides and conducting polymers have been used for their electrodes. However, most of these materials often suffer from low capacitance and high cost, so in this work, we attempted to use orange peel, a bio-waste, for electrochemical charge storage applications. The electrochemical properties of the carbonized orange peel were investigated by cyclic voltammetry (CV) and galvanostatic charge–discharge measurements in alkaline media. The CV curves showed a near ideal behavior with a specific capacitance of 267 F/g in 3 M KOH at a scan rate of 2 mV/s. The effect of the electrolyte (LiOH, NaOH and KOH) on electrochemical properties of the carbonized orange peel was also investigated. The results showed an excellent cyclic stability over 5000 cycles of charge-discharge, and no degradation in material's capacitive properties upon bending, suggesting that it can be used for flexible energy storage devices. We believe that this study provides a facile method to convert bio-waste into a high performance material for applications in the next generation of flexible and cost-effective energy storage devices.
9:00 PM - EE5.9.15
Highly Stretchable Coiled Yarn Supercapacitor
Changsoon Choi 1,Seon Jeong Kim 1
1 Hanyang Univ Seoul Korea (the Republic of),
Show AbstractReversibly deformable fiber based energy storage system are sought for such applications as power sources for wearable electronics and miniaturized devices. However, most previously reported fiber supercapacitors are nonstretchable with low energy storage performance, limiting possible use. We present here stretchable and highly performing fiber supercapacitors by inventing coil structured fiber electrodes. The elastomeric coiled electrode of the present solid-state supercapacitor is made by using a giant inserted twist to coiled carbon nanotube (CNT) fiber that is drawn from a CNT forest, and then electrochemically depositing pseudocapacitive MnO2 film onto the coil electode. Accordingly the energy storage capacity was effectively enhanced (512% increase in area of cyclic voltammogram (CV) after deposition). Therefore, we could achieve highly performing and stretchable electrodes by taking structural advantage of coiled yarns without the use of any elastomeric substrates, which enables high gravimetric and volumetric energy densities. The maximum linear, areal, and volumetric capacitances (based on total electrodes) of the coiled supercapacitor are higher than previous reported literature, despite the engineered elasticity. Moreover, these solid-state supercapacitors decrease capacitance by less than 16% when reversibly stretched by 37.5% in the length direction and largely retain capacitance while being cyclically stretched during charge and discharge.
9:00 PM - EE5.9.16
High Performance Flexible Double-Sided Micro-Supercapacitors with Redox Additive Organic Gel Electrolyte
Doyeon Kim 1,Daeil Kim 2,Geumbee Lee 1,Jeong Sook Ha 2
1 KU-KIST Graduate school of converging Science and Technology Korea university Seoul Korea (the Republic of),2 Department of Chemical and Biological Engineering Korea university Seoul Korea (the Republic of)1 KU-KIST Graduate school of converging Science and Technology Korea university Seoul Korea (the Republic of),2 Department of Chemical and Biological Engineering Korea university Seoul Korea (the Republic of)
Show AbstractAccording to the increasing demands for portable and functionalized electronic devices, much attention has been focused on developing wearable energy storage devices with high energy and power density. Among various energy storage devices, electrical double layer capacitor known as supercapacitor has advantages of fast charge-discharge, high power density, simple structure and cyclic stability while it has relatively low energy density.
Over the past few decades, studies on the effective electrode materials such as transition metal oxides and conducting polymer have been actively conducted to enhance the energy density of supercapacitors. In addition, it was recently reported that the performance of supercapacitor could be improved by introducing redox additive in electrolyte, via redox reactions at the interface between the electrodes and electrolyte.
In this work, we report on the fabrication of flexible planar micro-supercapacitor (MSC) with redox additive organic gel-electrolyte of poly(methyl methacrylate)-propylene carbonate-lithium perchlorate-hydroquinone (PMMA-PC-LiClO4-HQ). Hexagonal shaped MSC fabricated on a thin polyethylene terephthalate (PET) film has interdigitated electrodes of spray-coated multi-walled carbon nanotubes on Au with an interspace of 150 μm and a width of 500 μm. Use of organic gel electrolyte, PMMA-PC-LiClO4, increased the operational potential window up to 1.2 V. Addition of HQ in PMMA-PC-LiClO4 electrolyte increased the capacitance dramatically via combined charge storage mechanism of electrical double layer formation and faradic pseudocapacitance. Our MSC with PMMA-PC-LiClO4-HQ exhibits the areal capacitance of 6.14 mF/cm2 at a current density of 0.2 mA/cm2 which is ~20 times higher than that of MSC without HQ redox additive. Since the energy density (E) can be increased by increasing the capacitance (C) and the operation voltage (V) following the relationship of E=0.5CV2, use of PMMA-PC-LiClO4-HQ resulted in a dramatic increase in energy density to have 1.23×10-3 mWh/cm2 at a power density of 0.12 mW/cm2, which is also ~20 times higher than that of MSC without HQ redox additive. Furthermore, both areal capacitance and areal energy density could be doubled by fabricating double-sided MSCs where two MSCs are parallel connected. By encapsulation of the double-sided MSCs on PET with thin Ecoflex film, we could obtain stable electrochemical performance under repeated bending deformation over long time in air ambient conditions.
This work demonstrates the high potential of our flexible encapsulated double-sided MSCs with redox additive organic gel electrolyte as high performance wearable energy storage devices.
9:00 PM - EE5.9.19
Template-Free Synthesis of Hierarchical Mixed-Metal Oxides: Magnetic and Electrocapacitive Study
Dipesh Neupane 1,Hitesh Adhikari 1,J Candler 2,Ram Gupta 2,Bedanga Sapkota 3,Sanjay R Mishra 1
1 Univ of Memphis Memphis United States,2 Pittsburg State University Pittsburg United States3 Department of Physics North eastern University Cambridge United States
Show AbstractRecent years, increasing demand of energy looks for alternative energy sources and energy storage mechanism. Supercapacitors stand out best devices for energy storage because of its high specific power (>10 kW kg-1), long life time (>105 times), and fast charge–discharge process (within seconds) which make them attractive as power resources in high power electric devices and electric vehicles. In the present work, the synthesis of pure Co3O4, NiCo2O4, ZnCo2O4 and MnCo2O4 nanoparticles using template free hydrothermal method and annealed at 450OC for 5 hrs. Powder was examine from X-ray Diffracction(XRD) for crystalline structure and particle size. A pure spinel structure of Co3O4, NiCo2O4, ZnCo2O4 and MnCo2O4 nanoparticles were found with crystalline size range from 50nm to 90nm respectivity. Magnetic properties of these sample were measured by using Vibrating sample measurement (VSM). Saturation magnetization(Ms) of Co3O4 is 2.5 emu/g, NiCo2O4 is 8 emu/g, ZnCo2O4 is 2.9 emu/g and MnCo2O4 is 3 emu/g. Ms value for NiCo2O4 is higher comparatively than others is due to odd number of electron containing magnetic transition metal Ni. Morphologies of materials were examined by using SEM. Different concentration of urea and annealing temperature was responsible for the construction of hierarchical urchin-like microsphere. The electrochemical measurements were performed using standard three electrode system. The working electrode was prepared by mixing sample, acetylene black and PVDF in 80:10:10 Wt.% ratio in N-methyl pyrrolidinone. The mixed slurry was pasted onto nickel foam. Cyclic voltammograms (with 3M KOH electrolyte) were recorded in the potential window of 0 to 0.6 V. The anodic/cathodic peaks were observed and may be related to the formation of redox couple Fe+2/Fe+3 during charge transfer reaction. The specific capacitance at 1 A/g for NiCo2O4 was highest (150 F/g) while MnCo2O4 was 80 F/g and ZnCo2O4 was 75 F/g while lowest (60 F/g) for Co3O4. Furthermore, the specific capacitance for NiCo2O4 for 1 cycle is 265 F/g while 375 F/g for 2000 number of cycle. Similarly, sp. Capacitance for Co3O4, NiCo2O4, ZnCo2O4 and MnCo2O4 was 125, 350 150 and 175 F/g for 10 mV/s scan rate and decrease slowly for increasing of sacn rate and it is due to the chemical reaction occurs for higher scan rate. These values are superior to that of oxide (NiO, WO3 etc.) electrodes. It is thus shown that the samples prepared with different morphology gives higher energy. High pore volume is important to provide rich sites that can absorb ions and accelerate electron transfer or decrease electric resistance loss. Additionally, larger free-expanding volume and higher specific surface area in hierarchical urchin-like structures samples effectively improve capacitance behavior.
9:00 PM - EE5.9.20
2D Vanadium Doped Manganese Dioxides Nanosheets for Pseudocapacitive Energy Storage
Liang Huang 1,Zhimi Hu 1,Jun Zhou 1
1 Huazhong Univ of Samp;T Wuhan China,
Show AbstractManganese Dioxide (MnO2) generates high theoretical capacitance in pseudocapacitor. However, the poor conductivity and instability of MnO2 hinders their real application in high power, long lifetime need case. Therefore, promoting the conductivity of MnO2 becomes great necessary and urgent. In this work, V doped MnO2 ultrathin nanosheets have been successfully synthesized through facile hydrothermal method for the first time. Modification with V doping not only efficiently tailors the morphology tune to ultrathin nanosheets, but also improves the electronic conductivity. The V doped MnO2 nanosheets exhibit a significantly improved electrochemical performance due to the shortened ion transport distance in the nanoscaled dimension and enhanced electronic conductivity, with a high specific capacitance of 439 F/g (195 F/cm3, 141 mF/cm2) and capacitance retention of 50.4% from 0.5 A/g to 50 A/g. (Figure 1) After 10,000 galvanostatic charge-discharge (GCD) cycles in the 0.5 M Na2SO4 solution, V doped MnO2 nanosheets still kept 92% of initial capacitance. Besides, the V doped MnO2-based symmetric supercapacitors could deliver an energy density of 4.98 mWh/cm3 at the power density of 1.6 W/cm3. All the results demonstrated vanadium modification being an effective and convenient technique to tailor the morphology and improve the electrochemical performance of manganese dioxides-based supercapacitors, and should be applicable to a wide range of energy storage electrode materials such as MoO3, Nb2O5, WO3 and other metal oxides.
9:00 PM - EE5.9.21
Flexible Asymmetric Microsupercapacitor with MnO2 Nano-ball@MWNTs/ V2O5 Wrapped MWNTs Electrodes and Gel Electrolyte
Junyeong Yun 1,Yein Lim 2,Hanchan Lee 1,Geumbee Lee 2,Gwon Neung Jang 2,Heun Park 1,Soo Yeong Hong 1,Jeong Sook Ha 2
1 Department of Chemical and Biological Engineering Korea Univ Seoul Korea (the Republic of),2 KU-KIST Graduate School of Converging Science and Technology Korea University Seoul Korea (the Republic of)1 Department of Chemical and Biological Engineering Korea Univ Seoul Korea (the Republic of),2 KU-KIST Graduate School of Converging Science and Technology Korea University Seoul Korea (the Republic of)
Show AbstractAccording to the increased demand for miniaturized wearable and portable devices, research on embedded energy storage devices as well as flexible/stretchable electronics has been accelerated. Among various candidates as embedded energy storage devices, electrochemical capacitor known as supercapacitor has advantages of long cycling life, high safety, excellent charge/discharge performance, and high power density over batteries while it has drawbacks of low energy density, which can be improved by increasing specific capacitance and operation voltage. Fabrication of asymmetric supercapacitor (ASC) with two different electrodes of different potential ranges has been suggested in order to increase both specific capacitance and energy density. In particular, metal oxide electrodes exhibited excellent specific capacitance and stable charge/discharge characteristics compared to carbon based materials and conductive polymers.
In this work, we report on the fabrication of flexible planar asymmetric microsupercapacitor (AMSC) with high specific capacitance and energy density. As a positive electrode, potentiodynamically grown MnO2 nano-ball with a diameter of 80 nm onto carboxylic acid functionalized multi-walled carbon nanotubes (MnO2 nano-ball@MWNT) was used. Likewise, potentiodynamically deposited V2O5 on functionalized MWNTs in a form of wrapping MWNTs (V2O5 wrapped MWNTs) was used as a negative electrode. Owing to the large difference in work function between MnO2 and V2O5, the operation voltage of the AMSC could be extended to 1.6 V even in aqueous electrolyte of 0.5 M K2SO4. As a result, high energy density of 103.8 Wh/kg at a power density of 7.8 kW/kg and specific capacitance of 307.4 F/g at a current density of 5 A/g were obtained. Use of highly conductive MWNTs and highly pseudocapacitive metal oxides is partly attributed to such a high performance. Furthermore, in non-aqueous gel-type electrolyte of poly(methyl methacrylate)-propylene carbonate-lithium perchlorate (PMMA-PC-LiClO4), the specific capacitance was increased up to 540 F/g at 5 A/g, and higher energy density of 187.5 Wh/kg at a power density of 4 kW/kg was obtained. After 5000 cycles of charge/discharge, 80 % of initial capacitance was retained. The encapsulated AMSC exhibited mechanical stability upon repeated bending cycles with no noticeable degradation in electrochemical performance. Furthermore, the fabricated AMSCs can be connected in parallel and series to operate higher voltage μ-LEDs and the resultant energy density and output voltage can be controlled via changing the circuit design.
This work clearly shows the high potential of flexible AMSCs as embedded energy storage devices in future miniaturized wearable and portable electronics.
9:00 PM - EE5.9.22
Aqueous Manganese Dioxide Ink for High Performance Capacitive Energy Storage Devices
Jiasheng Qian 1,Shu Ping Lau 1,Jikang Yuan 1
1 Applied Physics the Hong Kong Polytechnic University Hong Kong Hong Kong,
Show AbstractPrintable electronics are of great interests in the areas ranging from thin film transistors (TFTs), energy storage devices, solar cells to micro electro-mechanical system (MEMS). Preparations of various inks composed of semiconductors, biological materials, single-walled carbon nanotubes (SCNTs), and graphene have been reported. Manganese dioxide is usually regarded as an ideal candidate for the electrode materials of portable devices, water treatment, up-conversion as well as photocatalysis. The conventional MnO2 electrodes are mainly prepared by two approaches: (1) nanostructured MnO2 or MnO2-containing composite precipitates via wet chemical process; (2) direct electrodeposition or chemical deposition on various substrates (e.g. glass, quartz, copper or aluminum foil). These existing preparation methods suffer from higher cost, complicated processes and superfluous contaminations. By now, it still remains a great challenge to synthesize MnO2 inks with high reliability and versatility. Nevertheless, few research works on aqueous MnO2 inks have been reported to date.
We report a simple approach based on a chemical reduction method to synthesize aqueous inorganic ink comprised of hexagonal MnO2 nanosheets. The MnO2 ink exhibits long term stability. Continuous thin films can be formed on various substrates without using any binder. To obtain a flexible electrode for capacitive energy storage, we printed the MnO2 ink on commercially available A4 paper pre-treated by multi-walled carbon nanotubes. The electrode exhibited a maximum specific capacitance of 1035 F/g (91.7 mF/cm2). Both paper-based symmetric and asymmetric capacitors were assembled. A maximum specific energy density of 25.3 Wh/kg and power density of 81 kW/kg were achieved. The device could maintain a 98.9% capacitance retention for 10,000 cycles at 4 A/g. The MnO2 ink could be a versatile candidate for large-scale production of flexible and printable electronic devices for energy storage and conversion.
9:00 PM - EE5.9.23
Au-Ag Core Shell Nanowire Network for Highly Stretchable and Transparent Supercapacitor Applications
Habeom Lee 1,Young Suh 1,Jinhyeong Kwon 1,Sukjoon Hong 2,Seung Hwan Ko 1,Hyunmin Cho 1
1 Seoul National University Seoul Korea (the Republic of),2 Mechanical Engineering University of California, Berkeley Berkeley United States
Show AbstractDue to the latest research trend toward wearable energy devices, transparent and stretchable supercapacitors which can sustain their performance even under physical deformation have steadily attracted huge attention. Despite the Ag NW is the most promising candidate for fabrication of transparent and stretchable electronics, the electrochemical instability interrupts its application to development of the energy device. Here, we introduce a transparent and highly stretchable supercapacitor made by Au-Ag core shell NW network percolation electrode. The Au-Ag core shell NW synthesized by a simple solution process not only shows excellent electrical conductivity but also greatly enhanced chemical and electrochemical stability compare to pristine Ag NW. These outstanding properties of the Au-Ag core shell NW are attributed both to the core Ag NW and the Au protecting sheath layer. The proposed Au-Ag core shell NW based supercapacitor exhibits optical transmittance with outstanding mechanical stability withstanding 60% strain without any decrease of the performance. The supercapacitors connected in series are charged and discharged stable in 30% strain turning on a red LED. These notable results demonstrate the potential of the Au-Ag core shell NW as a strong candidate for development of wearable energy devices.
9:00 PM - EE5.9.24
Holey Tungsten Oxynitride Nanowire Anode with High Rate Capability and Ultralong Cyclic Stability for Flexible Asymmetric Supercapacitors
Minghao Yu 1,Xihong Lu 1,Yexiang Tong 1
1 Sun Yat-Sen Univ Guangzhou China,
Show AbstractTo push the energy density limitation of supercapacitors, an efficient strategy is designing asymmetric supercapacitors (ASCs), which take advantage of different potential windows of cathode and anode to widen operating voltage. In recent years, considerable advances progress have been realized in fabrication of pseudo capacitive cathodes with high energy, yet the progress on anode materials is relatively slow that makes them hard to satisfy the demand of high energy matching with that of cathode. In this regard, designing novel and high-performance anode alternatives becomes a key outstanding issue in applications of ASCs.
Metal nitrides and oxynitrides are emerging as a new class of electrode materials for high-performance ASCs because they commonly possess excellent electrical conductivity (4000–55 500 S cm), high capacitance and suitable working windows in negative potential. However, most of them suffer from poor cycling stability that caused by their electrochemically instable nature (especially in aqueous solution), severely hindering their applications as high-performance anodes in ASCs. The development of novel metal nitride or oxynitride based anode with natural high-rate capability, large energy density and long-term stability has been highly pursued.
As a typical refractory transition metal oxynitride, tungsten oxynitride (WON) possesses a number of attractive properties such as high hardness, excellent conductivity, good thermal stability and high melting point. In this work, we constituted the first demonstration of WON as anode material for SCs. Holey WON nanowires on carbon cloth were constructed by directly calcination of tungsten trioxide (WO3) nanowires precursor under ammonia atmosphere. Quantities of micro and meso-pores with diameters of 1-20 nm are scattered on the nanowires. The novelly structured WON with superior conductive and hydrophilic properties enables it to achieve high electrochemical performance. An outstanding areal capacitance of 198.1 mF cm-2 was reached at a discharge current density of 0.5 mA cm-2 for WON electrode. When the discharge current density was increased to 40-fold, a high rate capability was demonstrated with 67.6 % capacitance retention. Moreover, the WON electrode showed an outstanding cycling stability with 93% capacitance retention after 100000 cycles, which was the best cycling performance ever reported for metal nitride or oxynitride. Such good performance further open up the opportunity to fabricating flexible ASCs with high energy density and power density. As expected, the ASCs based on WON anodes and MnO2 cathodes exhibited a maximum energy density of 1.27 mWh cm-3 and a maximum power density of 1.35 W cm-3.
9:00 PM - EE5.9.25
Preparation and Characterization of Carbon Nanotube Papers as Supercapacitors and Cathode Materials for Seawater Battery
Hsiao-Ling Chen 1,Kai-Hsuan Chen 1,Wen-Kuang Hsu 1
1 Materials Science and Engineering NTHU Hsinchu Taiwan,
Show AbstractElectrodes play an important role in determining the performance of electrochemistry properties, such as specific capacitance of supercapacitors and discharging capability of batteries. Recent studies focus on cathode materials and found that carbon nanotubes papers are one of potential cathode materials because of their light weight and low cost. Papers are flexible and may replace metal based cathodes for flexible mobile devices as well as table PC in the future. Here acid treated multi-walled carbon nanotubes are mixed with normal paper to form conductive papers. By upgrading specific area, we obtain a greater specific capacitance and scan current. For seawater batteries, carbon nanotube papers are used as cathode materials and magnesium alloy (AZ61) as anode. Electrons are released from alloy through oxidations and are then collected by carbon nanotube papers, resulting in H2 generation at cathode. Batteries discharge stably for a small current which is sufficient to power LEDs over 24 h. The physical properties and morphologies of carbon nanotube papers are characterized by field emission scanning electron microscopy and Raman measurement. The electrochemistry impedance spectrum analysis and linear sweep voltammetry are also studied. Finally, electrochemical properties of carbon nanotube paper are measured by index and particle diameter analysis.
9:00 PM - EE5.9.26
Engineered Pyrolysis Process towards the Synthesis of High Surface Area Supercapacitor Grade Carbon from Easily Available Biomass Precursors
Malik Wahid 2,Golu Parte 1,Ajay Kumar 1,Satishchandra Ogale 3
2 Physical amp; Materials Chemistry Division National Chemical Laboratory Pune India,1 Chemistry Indian Institute of Science Education and Research Pune India3 Physics Indian Institute of Science Education Research Pune India
Show AbstractAs biomass and bio-wastes contain rich compositions of carbohydrates, proteins, nucleic acids, fatty acids and many other carbon containing chemical backbones, a controlled pyrolysis of these precursors can be instrumental in the synthesis of functional carbon materials for a variety of applications. In our work we show that suitably controlled pyrolysis of unexplored biomass and bio-wastes such as Yogurt and Biogels like pectin prove to be novel and easily scalable precursors for supercapacitor grade carbon. Yogurt contains casein as the major protein besides some whey proteins. The yogurt forming process is mediated by bacteria, and hence this precursor has high nitrogen content which can get doped into carbon lattice upon controlled pyrolysis. It is thus shown to yield high quality heavily nitrogen doped porous carbon for the supercapacitor application. Indeed our material retains a high (12 wt.%) nitrogen percentage even after high temperature pyrolysis in the presence of an activating agent. A surface area of 1300 m2/g is attained with a good density of mesopores, apart from abundant micropores. The material offers a high capacitance of 225 F/g at 2 A/g which falls only to 200 F/g even at a high current density of 20 A/g in aqueous electrolyte. An energy density of 7 Wh/kg is delivered at a power density of 5000 W/kg. We have also examined the cathode performance of our material Vs Nickel cobalt sulfide (NCS) in an asymmetric configuration. Our energy density in asymmetric assembly goes as high as 27 Wh/kg at a power density of 364 W/kg and 17.8 Wh/kg at a power density of 6400 W/kg. In the case of biogels we have realized ex situ nitrogen doping by gelating them in aqueous solution of urea and hard templating inside SBA. The carbon obtained from our best performing biogel. By this procedure Pectin gives a capacitance of 285F/g at a current density of 1A/g and retains the value of 210F/g at 10A/g. The carbon obtained from two other biogels Sodium Alginate and Agarose by following this protocol gives a capacitance of 210F/g and 160F/g, respectively, which is 73% and 56% of the Pectin value. The higher performance of carbon derived from pectin gel as compared with structurally similar biogels (agarose and alginate) has been ascribed to minute dissimilarity in the spatial orientation of hydrogen bonding functional groups like OH, and -COOH.
9:00 PM - EE5.9.27
Thin-Film Carbide-Derived Carbon for Energy and Biomedical Applications
Greg Taylor 1,Zach Norris 1,Jesse Kosior 1,Anh Tran 2,Daniel Mason 2,Michael Graf 3,Lei Yu 2,Jeffrey Hettinger 1
1 Department of Physics and Astronomy Rowan University Glassboro United States,2 Department of Chemistry and Biochemistry Rowan University Glassboro United States3 Department of Physics Boston College Chestnut Hill United States
Show AbstractWe report on the synthesis and performance of carbide-derived carbon (CDC) films for micro-supercapacitor applications. The use of CDC materials as capacitor electrodes significantly increases the effective surface area of the electrodes due to the complex pore-structure these materials possess. Notable differences in performance of the CDC as an electrode are found for varying initial crystal structures and, to a certain extent, dependent upon the transition metal used to for m the binary carbide precursor. Synthesis parameters for reactively sputtered binary carbides films will be presented. The phase of binary carbide, cubic or hexagonal, can be adjusted by changing the acetylene/methane partial pressure during sputtering from a transition metal (V, Nb, Ta) target. The carbides grow as textured films on sapphire, thermal oxide, or glassy carbon. These substrates are selected since they do not react rapidly with chlorine gas used in the conversion from binary carbide to CDC though we present a technique for conversion that does not depend on the use of chlorine. The CDC conversion time depends on crystal structure, substrate, and conversion temperature. Methods for defining the micro-supercapacitor pattern are presented as well as details of the capacitance measurements.
9:00 PM - EE5.9.28
Three Shape Engineerable Composited Fibers Based on Carbon Nanomaterials
Kang Min Kim 1,Hyeon Jun Sim 1,Geoffrey Spinks 2,Seon Jeong Kim 1
1 Hanyang Univ Seoul Korea (the Republic of),2 Wollongong Univ Wollongong Australia
Show AbstractDue to excellent electrical and mechanical properties of carbon nano materials, it is of great interest to fabricate flexible, high conductive, and shape engineered carbon based fibers. As part of these approaches, hollow, twist, ribbon, and other various shapes of carbon based fibers have been researched for various functionality and application. In this paper, we suggest simple and effective method to control the fiber shape. We fabricate the three different shapes of hollow, twisted, and ribbon shaped fibers from wet spun giant graphene oxide (GGO)/single walled-nanotubes (SWNTs)/poly(vinyl alcohol) (PVA) gels. Each shapes have different properties and high strain characteristic. This mechanical performance is attributed by the wrinkled structures and sliding effect of lamellae along the layer of large size graphene and synergistic effect among GGO/SWNTs/PVA. Also, we demonstrate supercapacitor application which have high electrical capacitance from polymer removed ribbon shape fiber.
9:00 PM - EE5.9.30
Superconductive Polymer Supercapacitors: Conformal, Portable and Tactical Energy Solution
Young-Gi Kim 1,June-Ho Jung 5,Sabina Besic 5,Michael Birschbach 5,Von Ebron 5,Ramil Mercado 2,Patrick Kinlen 3,Hai-Long Nguyen 4
1 Delaware State Univ Dover United States,5 Crosslink St. Louis United States2 GAF Ennis United States3 Boeing Berkeley United States4 U.S. Army - Armament Research Development Engineering Center Picatinny United States
Show AbstractOrganic energy storage materials and the devices have been attracted a massive interest due to optimistic forecast for accomplishing reliable, light weight and flexible characteristics with pertinent performances in mobile electronics. Conventional battery and supercapacitor have been considered as for the primary energy and power storage sources for electronic devices in mobile era, respectively. However, the limitation in the energy and power of the energy storage devices was found to be a critical issue for addressing universal solutions for relevant mobile electronic devices. In accordance with the needs, one of the world’s best and niche electrochemical energy storage devices has been developed using state-of-the art advanced materials of superconductive polymer and nanostructured materials, for which the power density of superconductive polymer supercapacitor was observed to reach sub-Mega-Watts/Kg.
The discovery of superb electrochemical characteristics from advanced energy materials including organometallic materials, nano-crystals, carbon materials and electroactive polymers (EAPs) triggered off massive attraction, bringing out a remarkable accomplishments over the last decades. Facile modulation of electronic and electrical characteristics for the advanced EAPs by varying the molecular structure offered outstanding merits for developing innovative energy storage systems. Elucidation of structure and property relationship of the EAPs that included fluorescent polymers, conjugated polymers, variable band gap polymers and electrical conductive polymers was observed to be a solid platform to promise foreseeable and desirable innovations in the development of energy devices along with chemical, electrochemical, electrical, mechanical, optical analytical tools. Advancement in electrochemical and electrical characteristics of the EAPs was a key for acquiring the superb performance of superconductive polymer supercapacitors.
Nanotechnology was employed for processing the advanced materials and corresponding innovative prototypes of energy storage devices. Innovation in the superconductive EAPs and nanostructured carbon-initiative supercapacitors will be mainly addressed and followed by the perspectives of the innovation along with a broad scientific findings to engineering aspects.
9:00 PM - EE5.9.31
Organic Mesostructured Hybrid Electrodes for High-Performance Pseudocapacitors
Sung-Kon Kim 1,Jiung Cho 1,Jeffrey Moore 2,Ho Seok Park 3,Paul Braun 1
1 Department of Materials Science and Engineering and Beckman Institute for Advanced Science and Technology Urbana United States,2 Department of Chemistry and Beckman Institute for Advanced Science and Technology Urbana United States3 School of Chemical Engineering Suwon Korea (the Republic of)
Show AbstractOrganic hybrid mesostructured electrodes (termed pCy) that utilize the quinone (Q)-hydroquinone (QH2) couple, a prototypical organic redox system, are constructed by a colloidal crystal template-assisted electrosynthesis of pyrrole and catechol for high-performance pseudocapacitors. The Q/QH2 reaction provides fast and reversible proton-coupled electron-transfer reactions (i.e. two protons and two electrons per quinone) and the mesostructure offers good ion and electron transport pathways, enabling a high rate performance. During the electrosynthesis, the catechol becomes a polycyclic aromatic catechol derivative, and is adsorbed on the polypyrrole through non-covalent interactions (e.g., π-π and hydrophobic interactions). The catechol derivative electrochemically formed provides a highly reversible Q/QH2 redox process and plays an important role in enhancing the overall performance and lifetime of the electrodes. Specifically, the pCy electrode shows an exceptional volumetric capacitance as high as 130 F cm-3, excellent rate performance (75% of the low rate capacity), and a good cycle retention of 82% over at least 4000 charging/discharging cycles. Compared with a randomly structured electrode, the deterministically structured electrode exhibits an enhanced rate performance due to the facilitated electron and ion transports.
Symposium Organizers
Gleb Yushin, Georgia Institute of Technology
Bruce Dunn, University of California, Los Angeles
Arumugam Manthiram, University of Texas at Austin
Linda Nazar, University of Waterloo
Symposium Support
Arbin Instruments
BASF
BMW Group
OCSiAl
SABIC Americas, Inc
Toyota Research Institute of North America
EE5.10: Advanced Aqueous Batteries and Novel Cell Characterization
Session Chairs
Friday AM, April 01, 2016
PCC North, 200 Level, Room 231 A
9:00 AM - *EE5.10.01
Electrochemical Acoustic Time of Flight Analysis
Daniel Steingart 1,Andrew Hsieh 1,Greg Davies 1
1 Princeton Univ Princeton United States,
Show AbstractAll closed electrochemical energy systems are, by design, reactors which redistribute density (mass within a given volume) as a function of charged passed in the ideal case. Within a battery this is also a function of the cycle number as the cell degrades, allowing the consideration of a state of health (SOH) in reality. Regardless of the reaction mechanism, the density and elastic modulus of an electrode changes as a function of the charged passed, and this distribution as well as the rate of change of this distribution can act as a fingerprint of the SOH of the battery. For what we believe is the first time in literature, we have used acoustic ultrasonic transducers to probe gradual and gross changes in density distribution in real-time within a number of different battery chemistries, and have also provided a basic model which predicts how ultrasonic echoes within an arbitrary cell will change as a function of the SOC: we create time of flight maps of the acoustic signal, and the response matches the expected trend. An overview of the method wil be provided as well as demonstration of measurements for a variety of cell chemistries and geometries.
9:30 AM - EE5.10.02
Impact of Aqueous Electrolyte Concentration on Cycle Stability of Lithium Iron Phosphate
Daniel Gordon 1,Michelle Yu Wu 1,Anirudh Ramanujapuram 1,Jim Benson 1,Jung Tae Lee 2,Alexandre Magasinski 1,Naoki Nitta 1,Cindy Huang 1,Gleb Yushin 1
1 Materials Science and Engineering Georgia Institute of Technology Atlanta United States,1 Materials Science and Engineering Georgia Institute of Technology Atlanta United States,2 Massachusetts Institute of Technology Cambridge United States
Show AbstractThe development of an aqueous lithium ion battery (ALIB) has the potential to greatly improve the safety and lower the cost of lithium ion battery storage systems, while safeguarding the environment. The problem of thermal runaway and ignition of a flammable electrolyte is absent. Aqueous electrolytes exhibit higher ionic conductivities than their organic counterparts [1], allowing for the use thicker electrodes without suffering mass transport limitations. Combined, this promises to allow for a significant reduction in the amount of inactive components required to assemble a battery cell compared to a typical lithium ion battery cell with an organic electrolyte, helping to improve the final weight, volume and cost of an ALIB storage system [2]. Furthermore, the use of dry rooms and expensive and toxic organic electrolytes is avoided.
However, prior to commercialization of ALIBs, several challenges need to be overcome. There have been limited studies into the unique side reactions that occur between active materials and aqueous electrolyte, along with methods for reducing the impact of these side reactions on the battery performance [3]. In addition, creative solutions must be found to improve the voltage of the battery in view of the more limited potential window over which aqueous electrolytes are stable [4].
Here, we share the results of our systematic studies on the interactions of lithium iron phosphate (LFP) with aqueous electrolytes of varying composition. Increasing the lithium salt concentration of the electrolyte was found to significantly increase the cycle stability. Post-mortem analyses using microscopy (SEM, TEM), spectroscopy (XRD, EDS, FTIR, XPS), and depth profiling (TOF-SIMS), as well as electrochemical characterization using EIS and charge-discharge, help to elucidate the origins of the capacity fade and reasons for improved cycling stability with higher salt concentrations [2]. We propose that side reactions between water molecules and LFP lead to electrochemical separation of individual particles in the electrode, and that increasing the electrolyte molarity effectively reduces the concentration of water molecules available for these side reactions. We believe that lessons learned while studying the behavior of LFP in aqueous solutions will likely guide a path toward better understanding and optimizing the behavior of other intercalation materials in ALIBs, as we have already observed similar impacts of the aqueous electrolyte composition on the stability of lithium cobalt oxide (LCO) and lithium nickel manganese cobalt oxide (NMC).
References
[1] J.-Y. Luo, W.-J. Cui, P. He, Y.-Y. Xia, Nat. Chem. 2010, 2, 760
[2] D. Gordon, Y. Wu, A. Ramanujapuram, J. Benson, J.T. Lee, A. Magasinski, N. Nitta, C. Huang and G. Yushin, Adv. Energy Mater. 2015 [in press]
[3] Y. Wang, J. Yi, and Y. Xia, Adv. Energy Mater. 2012, 2, 830
[4] C. Wessells, R. Ruffo, R. A. Huggins, Y. Cui, Electrochem. Solid-State Lett. 2010, 13, A59
9:45 AM - EE5.10.03
Electrochemical Stability of Lithium Cobalt Oxide in Aqueous Electrolytes
Anirudh Ramanujapuram 1,Daniel Gordon 1,Alexandre Magasinski 1,Naoki Nitta 1,Jiaxin Huang 1,Brian Ward 1,Gleb Yushin 1
1 Georgia Institute of Technology Atlanta United States,
Show AbstractLithium cobalt oxide (LCO) has long been proven to be an excellent material for cathodes in organic electrolytes [1]. It has shown high volumetric capacity and good stability in non-aqueous environments of commercial lithium-ion (Li-ion) batteries. Unfortunately, the flammability of organic electrolytes in combination with a special propensity for batteries constructed with LCO to experience thermal runaway creates safety concerns [2].
Here we discuss electrochemical performance characteristics and stability of LCO in aqueous electrolytes. Aqueous electrolytes offer greatly improved safety and lower cost. In addition, they exhibit higher ionic motilities for the Li+ ions and thus can be potentially used for faster charging batteries [3] or batteries with thicker electrodes. While LCO has been demonstrated to cycle for 20-100 cycles in aqueous environments [4, 5], the causes of its degradation have not been investigated in detail.
In our previous work we have demonstrated promising characteristics of lithium iron phosphate (LFP) cathodes in aqueous electrolytes [6]. Here we further expanded our studies and demonstrated LCO cathodes with remarkably stable performance showing only 13 % fading after over 1500 cycles.
Post mortem analysis of the electrodes was conducted to understand the effect of cycling and the causes of degradation. A powerful combination of Fourier Transform Infrared spectroscopy (FTIR), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray Diffraction (XRD) have been utilized. Electrolyte composition was found to have a dramatic impact on the electrochemical performance and stability of LCO in aqueous environments. This talk will provide an overview of our findings and provide guidance for the future designs of aqueous electrochemical cells with stable cathodes.
References:
1.J. Zhang, Y.J. Xiang, Y. Yu, S. Xie, G.S. Jiang, C.H. Chen*, Journal of Power Sources 132 (2004) 187–194
2.J.R. Dahn, E.W. Fuller, M. Obrovac, U. von Sacken, Solid State Ionics 69 (1994,) 265-270
3.Yonggang Wang , Jin Yi , and Yongyao Xia*, Adv. Energy Mater. 2012, 2, 830–840
Gaojun Wang, Lijun Fu, Nahong Zhao, Lichun Yang, Yuping Wu,* and Haoqing Wu, Angew. Chem. Int. Ed. 2007, 46, 295–297
5.Riccardo Ruffo, Colin Wessells, Robert A. Huggins, Yi Cui*, Electrochemistry Communications 11 (2009) 247–249
6.D. Gordon, Y. Wu, A. Ramanujapuram, J. Benson, J.T. Lee, A. Magasinski, N. Nitta, J. Huang and Gleb Yushin, Advanced Energy Materials (2015) [in press]
10:00 AM - EE5.10.04
Atomic Layer Deposition of Vanadium Oxide on Carbon Substrates for Hybrid Energy Storage Devices
Simon Fleischmann 2,Nicolas Jaeckel 2,Marco Zeiger 2,Daniel Weingarth 1,Volker Presser 2
1 INM - Leibniz Institute for New Materials Saarbrücken Germany,2 Department of Materials Science and Engineering Saarland University Saarbrücken Germany,1 INM - Leibniz Institute for New Materials Saarbrücken Germany
Show AbstractSupercapacitors store electrical energy via fast and reversible electrosorption of ions on the surface of high surface area carbon electrodes. They provide a significantly higher power density than batteries, but suffer from a low intrinsic energy density [1]. A strategy to improve the energy density is to use hybrid electrodes which combine highly conductive carbons with redox-active materials, usually metal oxides [2, 3].
In this study, hybrid electrodes of carbon and vanadium oxide are fabricated by atomic layer deposition (ALD). Two different carbon substrates, namely carbon onions (OLC) and activated carbon (AC), were used and their suitability as substrate materials was investigated. OLCs are spherical nanoparticles of highly graphitized carbon with exclusively external surface area, whereas ACs consist mostly of amorphous carbon and are characterized by a wide pore size distribution, including inner-particle micropores in the sub-nanometer range. The coating thickness was varied and controlled on a sub-nanometer level by adjusting the number of ALD-cycles. The electrochemical performance was measured by cyclic voltammetry and galvanostatic charge/discharge in a half-cell setup with 1 M LiClO4 in acetonitrile as electrolyte. While the capacity of both hybrid electrodes is 120 mAhg-1 (equivalent to 360 Fg-1) at a low current density of 0.05 Ag-1 between 0 V and -1.2 V, the rate handling performance of OLC/VOx is superior to AC/VOx electrodes, retaining 83 % of capacity at 1 Ag-1 compared to 35 %. It is further shown that, for both substrates, thinner coatings show higher capacity retention at high current densities, while thicker coatings have higher values of capacity at low current densities.
10:15 AM - EE5.10.05
Utilization of Current Collector Geometry to Design Compliant Batteries: A Demonstration on Silver-Zinc Chemistry
Alla Zamarayeva 1,Igal Deckman 1,Michael Wang 2,Greg Davies 2,Daniel Steingart 2,Ana Claudia Arias 1
1 UC Berkeley Berkeley United States,2 Princeton University Princeton United States
Show AbstractRapid advancement of flexible wearable electronics generated a need for development of advanced compliant energy storage systems that are energy dense; maintain safe and stable operation under deformation. Here we report on combining silver- zinc battery chemistry with mechanic-guided device manufacturing approaches to enable high energy density compliant batteries with stable electrochemical performance along with improved resilience to mechanical stresses.
The batteries were fabricated utilizing current collector-electrode composites with enhanced structural design, like helical springs, serpentine and spirals. These architectures can effectively accommodate stress imposed by mechanical deformation, thus minimizing strain experienced by the electrodes and improving mechanical compliance of the battery. Depending on the choice of electrode design batteries can be fabricated with either flexible or stretchable form factors.
Batteries with helical band spring shape of the current collector-electrode composites comprise wire-shaped batteries. These batteries have high linear capacity of 1.2 mAh cm-1 and are resilient to repetitive dynamic mechanical load. They can withstand >17 000 bending cycles to the bending radius of 0.5 cm under continuous operation mode without decrease in electrochemical performance. Batteries with serpentine and spiral form factor are able to stretch up to 200% by utilizing stretchable properties facilitated by the out plane rotation of these structures.
EE5.11: Advanced Supercapacitors I
Session Chairs
Friday PM, April 01, 2016
PCC North, 200 Level, Room 231 A
11:15 AM - *EE5.11.01
Multidimensional Material and Device Architectures for Hybrid (Faradaic+Capacitive) Energy Storage of the Future
Maria Lukatskaya 1,Bruce Dunn 2,Yury Gogotsi 1
1 Drexel Univ Philadelphia United States,2 University of California, Los Angeles Los Angeles United States
Show AbstractAchieving a secure, sustainable energy future is one of the greatest scientific and societal challenges of our time. Electricity generated from renewable sources, such as solar and wind, is critical to meeting future energy demands. However, these intermittent renewable sources require efficient electrical energy storage (EES) devices. Thus the development of new EES systems is needed for large-scale solar- and wind-based electrical generation to be practical. Substantial improvements in the energy and power density of EES systems are also needed to realize the electrification of transportation and further the miniaturization of electronics and its integration into a variety of objects creating the Internet of Things.
The limitations of current EES devices expose fundamental gaps in our understanding of atomic- and molecular-level processes that govern their operation, performance, and failure. Herein, an overview will be presented of the development of a new generation of sustainable, affordable and safe EES technologies that will approach the theoretical limit for electrochemical storage and deliver electrical energy rapidly and efficiently.
Hybrids of batteries and electrochemical capacitors represent an important future direction for EES, where there is the promise of achieving high energy and power densities, well beyond what is anticipated from improvements in lithium-ion batteries or carbon-based electrical double-layer capacitors (EDLC). To achieve this goal, there is a need for novel materials and system architectures that enable electron transfer and ionic transport with multi-electron redox chemistries. In reviewing the status of research in this field, we indicate that an important future opportunity lies in the computationally driven design of new materials and hybrid energy storage devices. Finally, pathways to the integration of faradaic and capacitive storage mechanisms will be discussed.
11:45 AM - EE5.11.02
Fabrication and Characterization of Nb2O5/Carbide-Derived Carbon Pseudocapacitors
Chun-Han Lai 1,Melissa Moz 1,Yury Gogotsi 2,Bruce Dunn 1
1 Materials Science and Engineering University of California, Los Angeles Los Angeles United States,2 Materials Science and Engineering Drexel University Philadelphia United States
Show AbstractNiobium oxide (Nb2O5) is a promising pseudocapacitor material that stores charge through fast redox reactions. However, fabricating thick electrodes of Nb2O5 that retain its high energy density represents a significant challenge because of the large ohmic drop caused by the poor electronic conductivity of Nb2O5. Here, we focus on establishing pathways for fabricating electrodes of high thickness/material loading. The first part of the research is directed at overcoming the conductivity hurdles associated with thick electrodes. To solve this problem, we prepare highly conductive Nb2O5/reduced grpahene oxide (RGO) composites by hydrothermal synthesis using a homogeneous aqueous suspension of NbCl5 and graphene oxide. The solution is heated at 180°C for 12hr followed by washing and centrifuging. To obtain the orthorhombic phase of Nb2O5, the sample is annealed in argon at 500°C for 12hr. The as-prepared composites consist of 40-70 nm particles of Nb2O5 anchored on RGO sheets. The composite contains only 12%wt carbon from the RGO.
The second part of the research involves the addition of carbide-derived carbon (CDC) to Nb2O5/RGO composites to form thick electrodes. In this approach CDC is mixed with a Nb2O5/RGO suspension and dried. The Nb2O5/RGO exhibits conformal coverage over the CDC nanostructures due to its having an opposite surface charge during the mixing process. The electrochemical properties were determined for different ratios between CDC and Nb2O5/RGO. The optimum electrochemical properties were obtained with electrode compositions containing 40 wt% Nb2O5/RGO and 60 wt% CDC. The energy density of this material is 100 mAh/g at a rate of 2C. At 100C, the material still exhibits a reasonable capacity of 50 mAh/g. Gas adsorption measurements indicate that the CDC continued to have 70% porosity at that composition. This morphology suggests that charge is stored by both intercalation pseudocapacitance of Nb2O5 as well as the electrical double-layer formed on the CDC nanostructures. The composite electrodes were assembled into a full cell using activated carbon as the positive electrode. The resulting device operates up to 2V for the full cell, which can store 15.2 Wh/kg at a power density of 4750 W/kg.
12:00 PM - EE5.11.03
Microcapacitors Based on Silicon Nanostructures Operating in Ionic Liquid
Justyna Piwek 1,Anetta Platek 1,Krzysztof Fic 1,Dominika Gastol 1,Pascal Gentile 2,Gerard Bidan 2,Thomas Schubert 3,Elzbieta Frackowiak 1
1 Poznan University of Technology Poznan Poland,2 INAC/Dir, CEA/INAC Grenoble France3 IoLiTec Ionic Liquids Technologies GmbH Heilbronn Germany
Show AbstractIn the recent few decades multitude of studies have demonstrated that electrochemical capacitors are ideal short-term power devices which exhibit long cycle life. Many various materials have found an application in the construction of those devices. In fact, employing a solvent-free electrolytes like ionic liquids allows extending electrochemical voltage window, which significantly affects power and energy values. Additionally, temperature studies need to be taken into account due to possible specific implementations of electrochemical double layer capacitors (EDLCs) for such applications as airplanes or cranes which operate at high and low temperatures.
The main goal of this research was to examine performance of symmetric microcapacitors based on silicon nanostructured electrodes. In tested microcapacitor, the carbon electrodes from the conventional EDLC, have been replaced by SiNWires, SiNTrees, and SiNTrunks networks.
The experimental part consisted of the basic electrochemical methods but also life time tests, which are the most important from the application point of view. Moreover, three electrode measurements were performed in order to observe behaviour of each electrode separately. It was found that SiNTs, which are branches of ordered SiNWs, represent the most suitable electrode materials with three-fold higher capacitance values. Moreover, cycleability test proved that MPPyrr TFSI ionic liquid, employed as the electrolyte, exhibits a remarkable stability with only 15% loss of initial capacitance after 40 000 cycles at 0.1 mA cm-2 in operation voltage 3.5 V. In addition to this, data from temperature measurement, down to -40oC, show that electrochemical behaviour is retained, although a slight capacitance decrease is observed when the system is cooled down.
The successful results of electrochemical and physico-chemical tests of the microcapacitors in Swagelok® system confirmed the feasibility of scaling-up into coin- and pouch-cells.
It can be concluded that both systems reveal satisfactory characteristics, although coin cell assembly seems to be more appropriate due to very good electric contact (low values of internal resistance). By contrast pouch cell assembly allows constructing flexible design of device.
12:15 PM - EE5.11.04
Novel Chemistries for Aqueous Supercapacitors
Elzbieta Frackowiak 1,Jakub Menzel 1,Adam Kolodziej 1,Krzysztof Fic 1
1 Poznan Univ of Technology Poznan Poland,
Show AbstractElectrochemical capacitor performance has been improved by two approaches: application of a fluorine-free binder for electrode manufacturing and various combination of aqueous electrolytes. Considering the fact that chitin - a naturally occurring, abundant biopolymer - is insoluble in most common solvents including water, it appeared to be an interesting approach to introduce it as a binder for carbon electrodes operating in environmentally-friendly aqueous solutions. Chitin-based electrodes (with 10 wt % of chitin) have shown a perfect wettability supported by contact angle measurements. Excellent charge/discharge performance at high current load was proved in neutral aqueous electrolytes (1M lithium sulfate and 1M potassium iodide) with capacitance retention of ca. 80% of initial value for long-term cycling (over 10000 cycles). The high capacitance values close to 300 F/g have been reached in 1M KI solution merging electrical double-layer capacitance and faradaic contribution of the iodide/iodine redox couple. Perfect charge propagation was connected with good wettability of electrodes. Additionally, chitin played a beneficial role in the iodine trapping through the formation of a chitin complex with electrochemically generated iodine. It has been proved that chitin can easily replace commonly used fluorine based polymers such as polytetrafluoroethylene and/or polyvinylidenedifluorde which have rather negative impact on the environment.
As a second approach, high energy supercapacitor was built by using hybrid electrolyte system where both electrodes were operating in the different electrolytic media. Such hybrid system allowed us to extend safely a working voltage of capacitor in aqueous medium from 1.5 V to 2.0 V. Energy and power of capacitor with aqueous electrolytes of various elemental composition and pH reached the values comparable to organic medium.
12:30 PM - EE5.11.05
Nanoporous Carbon with Embedded Li4Ti5O12 Nanoparticles for High Energy Asymmetric Supercapacitors
Enbo Zhao 1,Chuanli Qin 2,Hong-Ryun Jung 1,Gene Berdichevsky 3,Alper Nese 3,Seth Marder 1,Gleb Yushin 1
1 Georgia Institute of Technology Atlanta United States,2 Heilongjiang University Harbin China3 Sila Nanotechnologies, Inc. Alameda United States
Show AbstractAs one of the superior anode materials for high power Li-ion batteries and asymmetric supercapacitors, spinel Li4Ti5O12 (LTO), has attracted significant attention in recent years owing to its unique characteristics.[1] Li4Ti5O12 exhibits a flat lithiation potential plateau at the voltage of ~1.55 V vs. Li/Li+, which largely prevents both excessive solid electrolyte interphase (SEI) formation and lithium dendrite growth. In addition, LTO is known for its “near-zero” volume change during repeatable lithiation and delithiation, which contributes to its excellent cyclic stability.
One major drawback of LTO to be qualified for high-rate performance is its poor electrical conductivity. One approach to improving electrical conductivity is doping of metal or nonmetal ions in Li, Ti or O sites, though the cyclic stability may be impaired and the resulting rate performance may still be insufficient for practical applications. Another drawback is that the Li-ion transport in LTO is slow compared with that of supercapacitor electrode materials.[2] Therefore, recent endeavors have been devoted to the design of LTO nanostructures and those with porous LTO morphologies, which demonstrated improved kinetics.[3] The synthesis of LTO nanoparticles has been extensively studied, however, it is still rather difficult to prepare uniform Li4Ti5O12 nanoparticles of small dimensions (e.g.,
12:45 PM - EE5.11.06
High Rate Pseudocapacitive Behavior in Two-Dimensional Ti3C2 and Mo2C MXenes
Sankalp Kota 2,Maria Lukatskaya 2,Mengqiang Zhao 2,Joseph Halim 2,Michel Barsoum 1,Yury Gogotsi 2
1 Department of Materials Science and Engineering Drexel University Philadelphia United States,2 A.J. Drexel Nanotechnology Institute Philadelphia United States,1 Department of Materials Science and Engineering Drexel University Philadelphia United States
Show AbstractMXenes - a recently discovered large family of two-dimensional (2D) early transition metal carbides and carbonitrides - have shown great promise for electrochemical energy storage applications, such as electrode materials for supercapacitors. We recently reported on large (as high as 900 F/cm3) volumetric capacitances of the most studied MXene to date, Ti3C2Tx, where T represents surface terminations. Spontaneous intercalation of a variety of monovalent and multi-valent cations, together with highly reversible electrochemical insertion of the same cations, has been well documented for Ti3C2Tx in aqueous electrolytes. It has also been demonstrated that the mechanism of charge storage in Ti3C2Tx in 1 M H2SO4 is pseudocapacitive, i.e., changes in the Ti oxidation state are detected during cycling.
Herein, we investigate the limit to the rate of charge storage in Ti3C2Tx and Mo2CTx – the most recently discovered MXene. Cyclic voltammetry studies in 1 M H2SO4 showed that perfect pseudocapacitive behavior is maintained at rates of at least 3 V/s with volumetric capacitances of 600 F/cm3 for both MXenes. According to electrochemical impedance spectroscopy, relaxation time constants as low as 15 ms were measured. Furthermore, electrochemical testing on thin MXene films (<1 µm thick) was used to probe the intrinsic limits of the rate performances of Ti3C2Tx and Mo2CTx and the effect of electrode architecture.
EE5.12: Advanced Supercapacitors II
Session Chairs
Elzbieta Frackowiak
Gleb Yushin
Friday PM, April 01, 2016
PCC North, 200 Level, Room 231 A
2:30 PM - *EE5.12.01
First-Principles Studies of Oxides as Electrochemical Pseudocapacitor Materials
Vidvuds Ozolins 1
1 Univ of California-Los Angeles Los Angeles United States,
Show AbstractElectrochemical supercapacitors (ECs) have important applications in areas where the need for fast charging rates and high energy density intersect, including in hybrid and electric vehicles, consumer electronics, solar cell based devices, and other technologies. In contrast to carbon-based supercapacitors where energy is stored in the electrochemical double-layer at the electrode/electrolyte interface, ECs involve fast and highly reversible faradaic ion intercalation into the electrode material. In contrast to batteries, ion intercalation does not lead to discontinuous phase transformations. Two key classes of EC electrode materials are (i) aqueous systems where energy storage is achieved by insertion and extraction of protons and (ii) lithium ion based systems. We discuss progress in first-principles density-functional theory (DFT) based studies of the electronic structure, thermodynamics, and kinetics of both types of supercapacitor materials, including hydrous ruthenium and tungsten oxides, orthorhombic T-phase niobium oxide, and reduced molybdenum oxide.
3:00 PM - EE5.12.02
Supercapacitors Based on CuSbS2 Nanoplates
Karthik Ramasamy 1,Ram Gupta 3,Hunter Sims 4,Sergei Ivanov 1,Arunava Gupta 2
1 Los Alamos National Laboratory Albuquerque United States,3 Department of Chemistry, Pittsburg State University Pittsburg United States4 German School of Simulation Sciences Julich Germany2 Center for Materials for Information Technology The University of Alabama Tuscaloosa United States
Show AbstractSupercapacitors store and release energy instantaneously, possess long-term stability and are much safer to handle as compared to batteries. Traditional supercapacitors based on carbonaceous materials work through the electrical double-layer capacitance mechanism that limits their energy density. A significant improvement in energy density can be achieved by use of metal oxide pseudocapacitors. However, their long-term stability is limited due to the volume change that occurs during charging and discharging processes and also unexpected secondary reactions that lead to degradation of the electrode materials. Layer-structured materials are advantageous for supercapacitor applications owing to their ability to host a variety of atoms or ions, large ionic conductivity and high surface area. In particular, ternary or higher-order layered materials provide a unique opportunity to develop stable supercapacitor devices with high specific capacitance values by offering additional redox sites combined with the flexibility of tuning the interlayer distance by substitution. CuSbE2 (E = S or Se) are ternary layered semiconductor materials that are composed of sustainable and less-toxic elements. We report solution-based approaches for the synthesis of mono-, few- and multiple layers of CuSbE2 (E = S or Se) and their systematic study for their use as supercapacitors along with the effect of ionic size of electrolyte ions on the specific capacitance and long-term cycling performance behavior. Electronic structure calculations based on density functional theory predict that with complete surface coverage by electrolyte ions a specific capacitance of over 1160 F/g is achievable using CuSbS2, making it a very attractive layer-structured material for supercapacitor applications. Additionally, the calculations indicate that lithium ions can be intercalated between the van der Waals layers without significantly distorting the CuSbS2 structure, thereby further enhancing the specific capacitance by 85 F/g. Quasi-solid-state flexible supercapacitor devices fabricated using CuSbS2 nanoplates exhibit an aerial capacitance value of 40 mF/cm2 with excellent cyclic stability and no loss of specific capacitance at various bending angles.
3:15 PM - EE5.12.03
Advanced Ti-Doped Fe2O3@PEDOT Core-Shell Anode for High-Energy Asymmetric Supercapacitors
Yinxiang Zeng 1,Xihong Lu 1,Minghao Yu 1
1 Sun Yat-Sen Univ Guangzhou China,
Show AbstractAs an efficient energy storage device, supercapacitor has attracted the extensive attention due to its fast charge-discharge rate, excellent cycling performance and environmentally friendly[1-2]. Over the past few years, great achievements have been made to cathode materials, whereas the progresses on the anode materials are relatively slow, which becomes the main barrier for the practical applications of ASCs[3]. Therefore, the exploration of low-cost anode materials with high capacitance is highly valuable and significant. Herein, we developed a new kind of Fe2O3 based anode by using Ti doped Fe2O3 nanorods as core and highly stable, conductive PEDOT layer as shell[4]. Such the unique core-shell architectures can offer high electrical conductivity of the overall electrode for charge transport, large interface area for reaction and numerous channels for rapid diffusion of electrolyte ions within the electrode, which enable the designed Ti-Fe2O3@PEDOT electrode to have excellent capacitive performances. The as-prepared Ti-Fe2O3@PEDOT core/shell electrode showed a remarkably large areal capacitance of 1.15 F cm-2 with outstanding rate capability. The Ti-Fe2O3@PEDOT electrode also exhibited ultrahigh cycling durability with more than 96% capacitance retention after 30000 cycles. To our knowledge, these are the best areal capacitance and capacitance retention values ever achieved for α-Fe2O3 electrodes. Based on this advancement, a flexible high-performance ASC device with a maximum energy density of 0.89 mWh cm-3 and a maximum power density of 0.44 W cm-3 was achieved. This work constitutes a promising strategy to rationally design and fabricate novel Fe2O3-based nanostructured anodes with largely enhanced capacitive behavior, which hold great promise in energy storage/conversion devices.
Reference:
[1] Xiao, X.; Ding, T.; Yuan, Y.; Shen, Y.; Zhong, Q.; Zhang, X.; Cao, Y.; Hu, B.; Zhai, T.; Gong, L.; Chen, J.; Tong, Y.; Zhou, J.; Wang, Z. Adv. Energy Mater., 2012, 2: 1328.
[2] Wang, X.; Lu, X.; Liu, B.; Chen, D.; Tong, Y.; Shen, G. Adv. Mater., 2014, 26: 4763.
[3] Lu, X.; Yu, M.; Zhai, T.; Wang, G.; Xie, S.; Liu, T.; Liang, C.; Tong, Y.; Li, Y. Nano Lett., 2013, 13, 2628.
[4] Zeng, Y.; Han, Y.; Zhao, Y.; Zeng, Y.; Yu, M.; Liu, Y.; Tang, H.; Tong, Y.; Lu, X. Adv. Energy Mater. 2015, DOI:10.1002/aenm.201402176.
3:30 PM - *EE5.12.04
High Energy Density Hybrid Type Supercapacitors
Mei Cai 1,Fang Dai 1,Bing Li 2
1 General Motors Warren United States,2 Tongji University Shanghai China
Show AbstractRapid growing commercial electrical device market evokes high demand of novel energy storage systems that can provide higher energy and power than traditional systems. Besides lithium-ion batteries (LIBs), supercapacitor has been recognized as promising system for power-based applications. Comparing with traditional dielectric capacitors, supercapacitors can provide higher energy density while maintaining the high power output. However, the energy-to-power ratio of current supercapacitors is still low comparing with other systems. Recently, a hybrid design which utilized traditional capacitor electrode as one electrode and LIB electrode as counter electrode has been demonstrated providing much higher energy density than traditional cell design. Here we report our studies on a hybrid type asymmetrical supercapacitor including electrode material screening, anode/cathode paring and corresponding cell design. Different carbon based materials including commercial and lab-made samples were evaluated for their electrochemical performance. Si-based materials which were also after screening work were utilized as the counter electrode for the asymmetrical cell configuration. The supercapacitor fabricated using the selected electrode materials were evaluated by varies of electrochemical methods to help determine the overall performance. The optimized supercapacitor device can deliver a high material level energy density of 230 Whkg-1 at 1747 Wkg-1, which remains of 141 Whkg-1 even when power density elevated to 30127 Wkg-1.
4:15 PM - *EE5.12.05
Microporous Carbons for Electrical Double Layer Capacitor: Charge Storage Mechanism and Electrochemical Performance
Patrice Simon 2,Wan Yu Tsai 2,Pierre Louis Taberna 2,Peihua Huang 2,Kevin Brouse 2
1 University Paul Sabatier, Toulouse III Toulouse France,2 Electrochemical Energy Storage French Network RS2E, FR CNRS 3459 Toulouse France,
Show AbstractIn the past decade, lot of attention has been put on electrochemical double layer capacitors (EDLCs), also known as supercapacitors, since they are one of the most promising electrochemical energy storage devices for high power delivery or energy harvesting applications. The charge storage mechanism in supercapacitor electrodes relies on electrostatic attraction between the electrolyte ions and the charges at the electrode surface, leading to a charge separation at the electrolyte/electrode interface.
During this presentation, we will show how the careful design of the carbon/electrolyte interface can help in designing high energy density carbons for supercapacitor applications. The combination of several experimental techniques like in-situ NMR spectroscopy and Electrochemical Quartz Crystal Microbalance together with Molecular Dynamics simulations has been used for studying the ion confinement effect in carbon nanopores and helped in developing our basic understanding of the electrolyte/carbon interactions in confined pores. Then, we will show results about the preparation of bulk, nanoporous carbon films with improved mechanical and electrochemical performance that be used to develop a new generation of high energy micro-supercapacitors directly integrated on Si wafers or flexible substrates. A last part of the presentation will present some perspectives for developing high-voltage systems based on the use of eutectic ionic liquid mixtures that can operate in a large temperature range.
4:45 PM - EE5.12.06
New Composite Cathodes for In Situ Pre-Lithiation of Graphite in Lithium Ion Capacitor
Francois Beguin 1,Pawel Jezowski 1,Olivier Crosnier 2,Thierry Brousse 2
1 Poznan University of Technology Poznan Poland,2 IMN University of Nantes Nantes France
Show AbstractThe lithium ion capacitor (LIC) is a high energy hybrid system which combines an electrical double-layer (EDL) positive electrode made from nanoporous carbon with a negative lithium intercalation electrode based on graphite [1]. The electrolyte is a lithium salt which is generally dissolved in ethylene carbonate : dimethyl carbonate (EC:DMC) mixture. In the first concept of LIC, an auxiliary metallic lithium electrode has been used for graphite pre-lithiation. Later, pre-lithiation has been proposed directly from the electrolyte [2] to circumvent the possible safety issues related with metallic lithium implementation, and also to simplify the device design. This leads to a decrease of electrolyte concentration and conductivity, which might have a negative impact on LIC power. Therefore, the most recent idea consists in irreversibly de-intercalating lithium from lithium metal oxide (lithium molybdenum oxide - Li2MoO3 or lithium iron oxide - Li5FeO6) incorporated in the positive activated carbon electrode [3]. However, in case of these oxides, the extraction potential of lithium ions exceeds 4.5 V vs. ref. Li/Li+, which causes detrimental electrochemical oxidation of the electrolyte.
In this presentation, we investigated new materials (lithiated oxides and lithiated organic molecules) from which high amount of lithium (can be irreversibly de-intercalated (up to 600 mAh/g) at potential lower than 4.5 V vs. ref. Li/Li+. The LIC cells realized from these materials demonstrate an excellent cycle life at current loads from 250 mAg-1 to 650 mA g-1 in the potential range from 2.2 ~ 4.0 V. The specific energy and power values are close to 50 Wh kg-1 and 500 W kg-1, respectively (for comparison, the energy density of EDLC is 3-10 Wh kg-1 [4]). The presentation will describe the synthesis and structural properties of the lithiated materials, the lithiation of graphite, and the electrochemical characteristics of these new LIC cells.
[1] T. Aida, K. Yamada and M. Morita, Electrochem. Solid-State Lett. 9 (2006) A534.
[2] V. Khomenko, E. Raymundo-Piñero, F. Béguin, J. Power Sources 177 (2008) 643.
[3] M.-S. Park, Y.-G. Lim, J.-H. Kim, Y.-J. Kim, J. Cho and J.-S. Kim, Adv. Energy Mater. 1 (2011) 1002.
[4] F. Béguin, E. Frackowiak, Supercapacitors: Materials, Systems and Applications, Wiley-VCH, Weinheim, 2013
5:00 PM - EE5.12.07
Heavily n-Dopable π-Conjugated Redox Polymers with Ultrafast Energy Storage Capability
Yanliang Liang 1,Yan Yao 1
1 Electrical amp; Computer Engineering University of Houston Houston United States,
Show AbstractOrganic polymers are a class of potentially environmentally friendly, energy-efficient, and cost-effective materials for energy storage applications. Hole-transporting (semi)conducting polymers with substantial redox activity and electronic conductivity have been long recognized as electrode materials for batteries and supercapacitors. However, all-polymer devices of this type have been difficult to realize due to the limitations of electron-transporting polymers. Pioneering attempts to construct an electron-transporting polymer with high n-dopability and electronic conductivity have been met with insufficient doping reversibility, unknown doping level, and uninvestigated/poor conductivity in the n-doped state. It has been a long-existing challenge to develop heavily n-dopable π-conjugated polymers with high electronic conductivity. In this presentation we will report our recent development of “π-conjugated redox polymers” which can be stably and reversibly n-doped to a high doping level (up to 2.0) and exhibit significant electronic conductivity, enabling ultra-fast energy storage. The success of our approach lies in the seamless combination of the high redox activity of non-conjugated redox polymers and the high electronic conductivity of π-conjugated polymers. Through comparison with a backbone-insulated control polymer, we have unambiguously demonstrated that it is the high electronic conductivity of π-conjugated redox polymers that has led to the best fast charge–discharge capability ever reported for an organic electrode material for batteries. The results strongly suggest our realization of a heavily n-dopable π-conjugated redox polymer is a new paradigm for the development of electron-transporting conducting polymer. We expect broad impact of our design strategy in polymer chemistry and wide application of the resulted polymers in various fields especially energy-related ones.
5:15 PM - EE5.12.08
Tailoring Metal Organic Framework Gels to Derive Highly Active Electrode Materials for Electrochemical Supercapacitors
Asif Mahmood 1,Qingfei Wang 1,Hassina Tabassum 1,Ruqiang Zou 1
1 Peking University Beijing China,
Show AbstractMetal organic frameworks (MOFs) represent one of the best examples of materials fabricated from molecular engineering with high surface areas, tunable porosity, inherent presence of coordinated metal and heteroatoms. Fabricating MOF-based nanostructures for electrochemical applications is a newly developed but fast growing field, which has shown huge impact on the development of state-of-the-art Li-ion batteries (LIB), supercapacitors (SC) and fuel cells (FC). MOFs have proved to be particularly suitable for electrochemical applications because of their tunable chemical composition that can be adjusted at molecular level and highly porous framework which allow faster mass transportation through the pores and provide highway for electrons via pore walls. However, it is quite difficult to tailor mesoporous MOFs. Here we have tailored new 3-dimensional materials which take benefit from MOF backbone and result in highly porous MOF gels. Recently, there is an increasing tendency to use MOFs as precursors to synthesize ideal composite structures. Traditionally MOFs could be calcined to several products including high surface area nanoporous carbon (NPC), metal oxides (MO) and metal decorated carbonaceous materials (M/MO@C). Apart from MOs, deriving NPC and MO@C have been very challenging, since calcination leads to reduction of metal into inactive metal/metal carbide particles. Considering the limitations of pure MO’s as electrode materials, it is very important to develop hybrid (MO@C) materials. Recently, we have used iron (Fe) based MOF gels to develop highly active electrode materials for supercapacitor electrode. The reduced Fe is converted to Fe3O4 upon exposure to KOH solution (which is also used as electrolyte), alleviating the use of post activation step. The Fe3O4/Fe/C hybrid shows high specific capacitance of 600 F/g at a current density of 1 A/g and excellent capacitance retention up to 500 F/g at 8 A/g. Furthermore, we also developed a new environment friendly method to obtain NPC from calcined product by a simple post treatment step with NaOH which display excellent capacitive performance of 272 F/g at 2 mV/s. We further elaborate the suitability of MOF based materials for SC application by assembling asymmetric supercapacitor (ASC). The ASC assembled entirely from MOF based electrode materials provide high energy density of 69.98 Wh/Kg at the power density of 1555.2 W/Kg. These strategies can help to expedite the development of MOF based materials for electrochemical applications.
A. Mahmood, W. Xia, N. Mahmood, Q. Wang, R. Zou, Scientific Reports 2015, 5, 10556., W. Xia, A. Mahmood, R. Zou, Q. Xu, Energy. Environ. Sci. 2015., N. Mahmood, M. Tahir, A. Mahmood, J. Zhu, C. Cao, Y. Hou, Nano Energy 2015, 11, 267-276., W. Xia, A. Mahmood, Z. Liang. R. Zou, S. Guo, 2015, 10.1002/ange.201504830, A. Mahmood, R. Zou et al., Under Review, J. Mater. Chem. A, Q. Wang, W. Xia, W. Guo, L. An, D. Xia, R. Zou, Chem. Asian. J. 2013, 8, 1879-1885.
5:30 PM - EE5.12.09
Chemistry of Aging Phenomena in High-Voltage Carbon-Based Supercapacitors Investigated by in situ Gas Analysis
Minglong He 2,Krzysztof Fic 1,Elzbieta Frackowiak 1,Petr Novak 2,Erik Berg 2
2 Electrochemistry Laboratory Paul Scherrer Institut Villigen Switzerland,1 Poznan University of Technology Poznan Poland
Show AbstractHigh-voltage carbon-based supercapacitors operating in aqueous electrolytes (U > 1.23 V) attract significant attention for next-generation high power, low cost and environmentally friendly energy storage applications. Cell ageing is however markedly pronounced at elevated voltages and results in accelerated overall performance fade and increased safety concerns. On-line electrochemical mass spectrometry, combined with cell pressure analysis, is for the first time shown to provide a powerful means for in situ investigation of degradation mechanisms in aqueous electrolyte/carbon based supercapacitors.
The activated carbon electrodes possess high specific surface area and oxygen-based surface functionalities (mainly phenol, lactone and anhydride groups), which are oxidized already at cell voltage of 0.6 V to provoke the evolution of minor amounts of CO and CO2. Noticeable water decomposition starts at high voltage of 1.6 V with the evolution of H2 on the negative electrode and carbon corrosion on the positive electrode with the generation of CO and CO2. In this paper we also report that short-term cycling leads to partly reversible gas evolution/consumption side-reactions giving negligible capacitance. On the other hand, long-term cycling causes irreversible side-reactions, deteriorates the electrochemical performance, and increases the internal pressure of the cell. Repeated galvanostatic cycling (U < 2 V) is confirmed as a more harmful technique for the electrode integrity compared to the voltage holding in a floating test. In situ gas analysis is shown to provide valuable insights into electrochemical cell ageing aspects, such as the nature and potential onsets of side reactions, hence paving the way for fundamental understanding and mitigating the performance and safety loss of high energy aqueous supercapacitors.