1‐Ethyl‐3‐Methyl‐Imidazolium Bis (Trifluoromethane‐ sulfonyl) Imide as an Electrolyte Additive in LiFePO4‐ Based Batteries for Suppressing Aluminum Corrosion

Abstract Lithium bis (trifluoromethanesulfonyl) imide (LiTFSI) is a potentially useful electrolyte salt for use in Li‐ion batteries. LiTFSI, however, is associated with severe corrosion of Al current collectors. This study investigates the ionic liquid 1‐ethyl‐3‐methyl‐imidazolium bis (trifluoromethanesulfonyl) imide (EMITFSI) as an Al corrosion inhibitor in LiTFSI electrolytes. Different concentrations of EMITFSI are used as additives in 1 m LiTFSI‐based electrolytes to systematically assess the performance of lithium iron phosphate (LiFePO 4 ) cathodes. The results from electron microscopy (SEM), X‐ray photoelectron spectroscopy (XPS), Cyclic voltammetry (CV) indicate that adding EMITFSI into LiTFSI‐based electrolytes can effectively prevent severe corrosion of Al caused by LiTFSI‐based electrolytes. The LiFePO 4 cells that use 1 m LiTFSI+11 % EMITFSI‐based electrolytes demonstrate a superior rate capability and cycling stability when compared to cells that use the LiTFSI‐based electrolyte.