Regulating the interfacial chemistry of graphite in ethyl acetate‐based electrolyte for low‐temperature Li‐ion batteries

Abstract

AbstractLithium‐ion batteries suffer from severe capacity loss and even fail to work under subzero temperatures, which is mainly due to the sluggish Li+ transportation in the solid electrolyte interphase (SEI) and desolvation process. Ethyl acetate (EA) is a highly promising solvent for low‐temperature electrolytes, yet it has poor compatibility with graphite (Gr) anode. Here, we tuned the interfacial chemistry of EA‐based electrolytes via synergies of anions. ODFB− with low solvation numbers, participates in the solvation sheath, significantly reducing the desolvation energy. Meanwhile, combined with the high dissociation of FSI−, the reduction of both anions constructs an inorganic‐rich SEI to improve interfacial stability. The electrolyte enables Gr anode to deliver a capacity of 293 mA h g−1 and 2.5 Ah LiFePO4||Gr pouch cell to exhibit 96.85% capacity retention at −20°C. Remarkably, LiFePO4||Gr pouch cell with the designed electrolyte can still retain 66.28% of its room‐temperature capacity even at −40°C.