April 7 - 11, 2025
Seattle, Washington
Symposium Supporters
2025 MRS Spring Meeting & Exhibit
EN01.15.01

Tailoring Linear Organic Carbonates for Safer Li-Ion Batteries

When and Where

Apr 11, 2025
9:45am - 10:00am
Summit, Level 3, Room 327

Presenter(s)

Co-Author(s)

Jina Lee1,A-Re Jeon1,Hye Jin Lee2,Ukseon Shin3,Yiseul Yoo4,5,Hee-Dae Lim6,Cheolhee Han7,Hochun Lee7,Yong Jin Kim2,Jayeon Baek2,Dong-Hwa Seo3,Minah Lee1

Pohang University of Science and Technology1,Korea Institute of Industrial Technology2,Korea Advanced Institute of Science and Technology3,Korea Institute of Science and Technology4,Korea University5,Hanyang University6,Daegu Gyeongbuk Institute of Science and Technology7

Abstract

Jina Lee1,A-Re Jeon1,Hye Jin Lee2,Ukseon Shin3,Yiseul Yoo4,5,Hee-Dae Lim6,Cheolhee Han7,Hochun Lee7,Yong Jin Kim2,Jayeon Baek2,Dong-Hwa Seo3,Minah Lee1

Pohang University of Science and Technology1,Korea Institute of Industrial Technology2,Korea Advanced Institute of Science and Technology3,Korea Institute of Science and Technology4,Korea University5,Hanyang University6,Daegu Gyeongbuk Institute of Science and Technology7
Lithium-ion batteries (LIBs) are essential in numerous applications, from portable electronics to electric vehicles and grid storage. Despite their widespread use, safety concerns, particularly the risk of fires, pose significant challenges due to the flammability of current commercial electrolytes. The electrolytes typically contain lithium hexafluorophosphate (LiPF6) dissolved in a blend of ethylene carbonate (EC) and linear carbonates, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), and ethyl methyl carbonate (EMC). While EC stabilizes the solid electrolyte interphase (SEI) on the graphite anode and solubilizes Li ions, the addition of linear carbonates to adjust the viscosity of the solution also leads to low flash points, inevitably making the electrolytes highly flammable. This can lead to thermal runaway and catastrophic fires under abuse conditions.
To date, various strategies have been explored to reduce the flammability of electrolyte, including the use of flame-retardant additives like organic phosphates. These compounds inhibit combustion by trapping reactive radicals; however, they also exfoliate the graphite anode surface, thus reducing battery life and practicality. Fluorination of phosphate solvents has shown promise in improving compatibility with graphite. However, the fluorinated compounds pose concerns, such as toxicity and the formation of hazardous byproducts such as hydrofluoric acid (HF) at high temperatures. Additionally, high-concentration electrolytes (HCEs) and their fluorinated, diluted equivalents, such as 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropyl ether (HFE), demonstrate enhanced thermal stability and low volatility. However, high costs, increased viscosity, and low conductivity limit their widespread application.
In response to the safety challenges in LIBs, our study introduces bis(2-methoxyethyl) carbonate (BMEC) as a rationally designed, low-flammability electrolyte solvent. BMEC is engineered through structural modifications of diethyl carbonate (DEC), specifically alkyl chain extension and alkoxy substitution. This extended chain length suppresses vaporization by strengthening intermolecular interactions, resulting in a substantial increase in flash point from 31°C to 121°C due to reduced vapor pressure. At the same time, comprehensive characterization via spectroscopy and computational simulations reveals that the additional ethereal oxygen atoms in BMEC significantly enhance Li-ion solvation, promoting improved ion dissociation and transport. This enhanced ionic mobility enables efficient cycling with commercial electrode materials, making BMEC a promising electrolyte for safer, high-performance LIBs.
The performance test demonstrates that the BMEC-based electrolyte sustains stable charge-discharge cycles for over 500 cycles with graphite and nickel-rich oxide electrodes in a 1 A h pouch cell configuration. Notably, BMEC enhances safety by delaying and suppressing exothermic reactions with cathodes that could generate oxygen under abuse conditions. As a result, in a nail-penetration test simulating severe mechanical abuse, a 4 A h pouch cell containing BMEC remains intact, whereas an equivalent cell with a commercial electrolyte experiences immediate thermal runaway. These findings indicate that BMEC meets essential safety and performance standards for LIB electrolytes, offering a readily applicable solution to mitigate LIB fire hazards without sacrificing efficiency. Furthermore, this study highlights the feasibility of incorporating BMEC into existing commercial battery systems by controlling the molecular structure of linear carbonates. It also underscores how tailored molecular modifications possibly provide critical insights into addressing broader safety challenges in battery design.

Keywords

organic | surface chemistry

Symposium Organizers

Junjie Niu, University of Wisconsin--Milwaukee
Ethan Self, Oak Ridge National Laboratory
Shuya Wei, University of New Mexico
Ling Fei, The University of Louisiana at Lafayette

Symposium Support

Bronze
BioLogic
Neware Technology LLC

Session Chairs

Junjie Niu
Shuya Wei

In this Session