N. Rodrigo, Chamithri Jayawardana, Leah Rynearson
Oct 24, 2022
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0
Influential Citations
2
Citations
Journal
Journal of The Electrochemical Society
Abstract
An investigation of using 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 NCM622║graphite cells to improve low-temperature cycling performance of lithium ion batteries at -20˚C. Improved low-temperature performance was observed for all of these lithium salts in MA/FEC electrolyte compared to LiPF6/carbonate electrolytes, while comparable room-temperature (25˚C) capacities were only obtained for electrolyte using LiPF6 salt. Detailed ex-situ analysis of surface films generated in ester-based electrolytes using LiBF4, LiDFOB, and LiPF6 reveals that the solid electrolyte interphase (SEI) is predominately composed of lithium salt decomposition products and the addition of 10% FEC (by volume%) may not be sufficient at forming a stable protective SEI.