Uncoupling Solvent Cointercalation on Graphite Anode in Lithium‐ion Batteries

ABSTRACT Graphite anodes have severe compatibility issues with most non‐aqueous electrolytes, which is known as a critical bottleneck hindering the advancement of lithium‐ion batteries (LIBs). The reduction of non‐aqueous solvents on graphite anodes involves complex processes, mainly including solvent co‐intercalation and decomposition. While much research focuses on solvent decomposition and the related solid electrolyte interphase (SEI) formation, investigations into solvent co‐intercalation are limited to solvents with high reductive stability (i.e., ethers). Herein, we demonstrate that reversible solvent co‐intercalation is an universal side reaction threatening the stability of the graphite anode. Besides ether‐based solvents, the reversible co‐intercalation into graphite can be achieved by three commonly used functional solvents, Trimethyl phosphate (TMP), Triethyl phosphate (TEP), and Tetramethylene sulfone (TMS). By systematically analyzing these reversible solvent co‐intercalation reactions, the solvating power of the solvent and Li + solvation structure were found to be the two critical factors determining the onset voltage of solvent cointercalation. The approaches to effectively protecting graphite from solvent cointercalation were also discussed. This work provides new insights into the understanding of electrolyte||graphite anode interface and shed lights into the development of high‐performance electrolytes for LIBs.