Highly promising lithium difluorophosphate additive for excellent cycling performance of graphite anodes at high rates

Abstract

Recently, lithium-ion batteries (LIBs) have gained recognition as reliable power sources for transportation applications. However, LIBs suffer from inferior rate capability, high cost, and safety issues. To achieve good performance in terms of power, the electrodes should allow rapid charge transport at the electrode-electrolyte interface and good electronic conduction at the electrode-current collector interface. Solid electrolyte interphase (SEI) between bulk electrolyte and the graphite anode surface is a crucial parameter which determines the performance of LiBs at high rate. The formation of protective films on the anodes through the use of reducible additives such as vinylene carbonate (VC) can lead to a noticeable improvement in the electrochemical properties of the anodes. Here, we present, for the first time, the highly promising lithium difluorophosphate (LiDFP) additive for the formation of more ionic conductive surface film on the graphite anode. LiDFP additive is successfully employed to overcome the poor rate capability and cycling instability of graphite anodes, which have the VC-derived surface. The combination of a novel additive, LiDFP, and VC contributed to the formation of a more ionically conductive and stable SEI layer, allowing faster kinetics of the graphite anodes and profoundly reducing electrolyte decomposition at the anode during cycling.