Rapid charging of graphite negative electrode by acetonitrile localized high-concentration electrolyte

Abstract Lithium ion batteries using traditional carbonate electrolytes do not show excellent fast charging performance, while acetonitrile (AN) exhibits excellent reduction stability and fast charging ability in high concentration electrolytes (HCEs) system. In this paper, a localized high-concentration eletrolyte (LHCE) was formed by using AN as solvent, lithium bis(fluorosulfonyl) imide (LiFSI) as lithium salt and fluorine-containing solvent (1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropyl ether (TTE)) as diluent, and applied to graphite anode to explore its fast charging ability. The solvation structure of electrolyte was analyzed by Raman spectroscopy, and the appearance of graphite anode was observed by scanning electron microscope(SEM). At the same time, linear sweep voltammetry (LSV) and cyclic voltammetry (CV) were used to investigate the electrochemical characteristics of the electrolyte. Based on the excellent electrochemical stability and multiplication of the localized high-concentration eletrolyte (LHCE) , the graphite/Li half battery can reach a high capacity of 388 mAh g-1 at 0.2 C and still reach 205 mAh g-1 at a high magnification of 5 C , what’s more the capacity retention rate is about 90% after 100 cycles at 5C. This study provides a high reference value for the design of localized high-concentration eletrolyte（LHCE） system with high concentration effect of acetonitrile group on graphite electrode.