Inhibiting Solvent Co-intercalation into Graphite Anode by Constructing an Anion-Rich Artificial Solid Electrolyte Interphase

Propylene carbonate (PC) is a promising electrolyte solvent with a wide liquid-phase temperature range, which can improve the wide-temperature performance of lithium-ion batteries (LIBs). Unfortunately, PC easily co-intercalates into graphite (Gr) interlayers with Li + and leads to the exfoliation of the Gr structure. Herein, we demonstrate that an anion-rich artificial solid electrolyte interphase (SEI) on the surface of Gr, constructed by the polymeric ionic liquid (PIL) solid polymer electrolyte (SPE), can significantly suppress co-intercalation of the PC solvent, so that the Gr electrode can adequately work in PC-based electrolytes. This is mainly owing to the PIL SPE layer, which provides a high local concentration of TFSI − anions and selectively excludes the solvent-separated ion pair (SSIP) configuration of Li + -PC from entering the graphite interface. Meanwhile, a robust anion-derived inner SEI layer can be formed on the Gr surface through the preferential decomposition of anions. Therefore, the PIL SPE layer can effectively achieve highly reversible lithiation/delithiation of the Gr electrode in a a PC-based electrolyte. Consequently, the Gr||LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523) pouch cell with a a PC-based electrolyte exhibits a high capacity of 3060 mAh, an extremely high CE of ≈100%, and good cycling stability with 97.1% capacity retention after 200 cycles. Acceptable rate capability and good low-temperature performance at –20 °C are also achieved in this pouch cell.