Perfluoropolyether‐terminated Single‐ion Polymer for Enhancing Performance of PEO‐based Solid Polymer Electrolyte

Solid-state electrolytes are receiving increasing attention in lithium metal batteries due to the advantage of high energy density. Poly(ethylene oxide) (PEO) electrolyte possesses good compatibility with lithium salts. However, PEO suffers from a low lithium-ion transference number and poor high-voltage resistance, which significantly hinder its application in lithium metal batteries. Herein, a perfluoropolyether-terminated single-ion polymer (PFPE-polymer) is designed and synthesized in this contribution. By incorporating the PFPE-polymer and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) into PEO via casting, the polymer electrolyte (PFPE-SE) is successfully prepared. Compared to PEO-based electrolytes, PFPE-SE forms a solid electrolyte interface (SEI) layer and inhibits the growth of lithium dendrites on the anode. At 70 °C, the lithium-ion transference number