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Engineering A Boron-Rich Interphase with Nonflammable Electrolyte toward Stable Li||NCM811 Cells Under Elevated
Chao Yang1, Mengting Zheng2, Rui Qu3
1State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei, 430070, P. R. China.
Advanced Materials (Deerfield Beach, Fla.)
|September 24, 2023
Summary
Researchers developed a novel electrolyte strategy to enhance the stability and safety of lithium nickel cobalt manganese oxide (NCM811) batteries, especially at high temperatures. This approach improves cycling performance and reduces solvent decomposition for safer, long-lasting energy storage.
Area of Science:
- Materials Science
- Electrochemistry
- Energy Storage
Background:
- Lithium nickel cobalt manganese oxide (NCM811) cathodes offer high energy density but suffer from rapid degradation at elevated temperatures due to solvent decomposition and unstable cathode electrolyte interphase (CEI) layers.
- The reaction between delithiated NCM811 and flammable electrolytes poses significant safety risks, particularly under high-temperature conditions.
Purpose of the Study:
- To address the critical issues of solvent decomposition and battery safety in NCM811 cathodes operating at high temperatures.
- To develop a universal electrolyte design strategy for stable and safe high-temperature operation of NCM811 cathodes.
Main Methods:
- Engineered electrolytes by utilizing salts with higher highest occupied molecular orbital (HOMO) levels and nonflammable solvents with lower HOMO levels.
- Investigated the formation of a thin, boron-rich CEI layer and its impact on inhibiting side reactions.
- Compared the performance of the novel dilute electrolyte formulation against highly concentrated electrolytes.
Main Results:
- The engineered electrolyte significantly reduced solvent decomposition and improved battery safety under elevated temperatures.
- A robust, inorganic-rich, boron-rich CEI layer was formed, effectively suppressing side reactions and enhancing cycling stability.
- NCM811 cathodes demonstrated high capacity retention: 81.2% after 950 cycles at 25°C and 75% after 300 cycles at 55°C.
Conclusions:
- The proposed electrolyte design strategy offers an effective and practical alternative for developing stable and safe high-temperature electrolytes for NCM811 cathodes.
- This approach enables the formation of a protective inorganic-rich CEI using significantly less salt compared to highly concentrated electrolytes.
