Date of Original Version
An investigation of alternative lithium salts, lithium tetrafluoroborate (LiBF4), lithium difluoro(oxalato)borate (LiDFOB) and lithium hexafluorophosphate (LiPF6), in novel ester-based (methyl acetate/fluoroethylene carbonate- MA/FEC or methyl propionate/fluoroethylene carbonate- MP/FEC) electrolyte formulations has been conducted in LiNi0.6Co0.2Mn0.2O2 (NCM622)/graphite cells to improve low temperature cycling performance of lithium ion batteries at −20 °C. Improved low temperature performance was observed with all the lithium salts in MA/FEC electrolyte while comparable room temperature (25 °C) capacities were observed with LiPF6 salt only. Detailed ex-situ analysis of surface films generated with LiBF4, LiDFOB and LiPF6 in ester-based electrolytes reveals that the solid electrolyte interphase (SEI) is predominately composed of lithium salt decompaction products and addition of 10% FEC (by volume%) may not be sufficient at forming a protective SEI.
Publication Title, e.g., Journal
Journal of The Electrochemical Society
Rodrigo, N. D., Jayawardana, C., Rynearson, L., Hu, E., Yang, X.-Q., & Lucht, B. L. (2022). Use of Ethylene Carbonate Free Ester Solvent Systems with Alternative Lithium Salts for Improved Low-Temperature Performance in NCM622∣∣ Graphite Li-ion Batteries. Journal of The Electrochemical Society, 169(11), 110504. https://doi.org/10.1149/1945-7111/ac9d0a
Available at: https://doi.org/10.1149/1945-7111/ac9d0a
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