Boosting Li-ion transport for graphite electrodes with lithium bis(fluorosulfonyl)imide salt and methyl acetate additive for fast-charging Li-ion batteries

Lithium-ion battery (LIB) is now widely used in the world. However, its unsatisfactory fast-charging performance is limiting its applications. The fast-charging capability of LIB is highly affected by the surface composition of graphite electrode, which can be modified through electrolyte design. Herein we demonstrate that the combination of lithium bis(fluorosulfonyl) imide (LiFSI) salt with methyl acetate (MA) additive in carbonate electrolyte enables fast-charging Li-ion battery. Results from X-ray photoelectron spectroscopy and transmission electron microscopy indicate that the LiFSI-based electrolyte with MA forms a stable and less-resistive solid electrolyte interphase on graphite anode compared to electrolyte with LiPF6, facilitating the transport of Li-ion and achieving a superior fast-charging performance with a capacity of 230 mAh g−1 at 2 C. An electrolyte swapping experiment also indicates that the LiFSI salt forms a more stable SEI on graphite than LiPF6. This work provides a conducive electrolyte design for fast charging Li-ion battery with graphite anode.