Date of Original Version
The use of methyl acetate (MA) and methyl propionate (MP) as co-solvents in carbonate/LiPF6 electrolytes have been investigated in LiNi0.5Co0.2Mn0.3O2 (NCM523)/graphite cells to improve electrochemical performance at low temperature (-20 °C). Consistent with previous investigations, improved low temperature performance was observed with all electrolyte formulations containing esters. Detailed ex situ surface analysis of the surface films generated with the ester-based electrolytes containing electrolyte additives reveal significant changes to the SEI on graphite upon cycling at moderately elevated temperature (45 °C). In the presence of vinylene carbonate (VC) lithium plating is observed upon cycling at low temperature (-20 °C) which leads to a thicker solid electrolyte interface (SEI) upon cycling at 45 °C. Incorporation of fluoroethylene carbonate (FEC) as an electrolyte additive results in the generation of a thin SEI and alters the structure of the surface film on the NCM523 cathode resulting in stable cycling over a wide temperature range.
Publication Title, e.g., Journal
Journal of the Electrochemical Society
Rodrigo, Nuwanthi D., Chamithri Jayawardana, and Brett L. Lucht. "Investigation of the Electrode-Electrolyte Interphase in Ester-Based Electrolytes in NCM523/Graphite Cells." Journal of the Electrochemical Society 169, 3 (2022). doi: 10.1149/1945-7111/ac5a19.
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