Mitigating Swelling of the Solid Electrolyte Interphase using an Inorganic Anion Switch for Low‐temperature Lithium‐ion Batteries

Abstract In overcoming the Li + desolvation barrier for low‐temperature battery operation, a weakly‐solvated electrolyte based on carboxylate solvent has shown promises. In case of an organic‐anion‐enriched primary solvation sheath (PSS), we found that the electrolyte tends to form a highly swollen, unstable solid electrolyte interphase (SEI) that shows a high permeability to the electrolyte components, accounting for quickly declined electrochemical performance of graphite‐based anode. Here we proposed a facile strategy to tune the swelling property of SEI by introducing an inorganic anion switch into the PSS, via LiDFP co‐solute method. By forming a low‐swelling, Li 3 PO 4 ‐rich SEI, the electrolyte‐consuming parasitic reactions and solvent co‐intercalation at graphite‐electrolyte interface are suppressed, which contributes to efficient Li + transport, reversible Li + (de)intercalation and stable structural evolution of graphite anode in high‐energy Li‐ion batteries at a low temperature of −20 °C.