Synthesis and Application of a Conjugated Polydianion‐Based Single‐Ion Conducting Polymer for High‐Performance Solid Lithium‐Ion Batteries

Abstract Fluorosulfonimide lithium salts have been widely used as conductors in solid polymer electrolytes for solid Li‐ion batteries (LIBs). However, low conductivity and poor compatibility with the polymer host (usually polyethylene oxide, PEO) remain challenges in the design of these salts. In this paper, we synthesized a highly Li + ‐conductive salt containing the poly(perfluoroalkylsulfonyl)diimide (PFSDI − ) dianion for the first time. LiPFSDI represents the first example of a single Li‐ion‐conducting polymer (SLICP) with a conjugated sulfonimide moiety (−SO 2 −N (−) −SO 2 −N (−) −SO 2 −). The PEO−LiPFSDI blend electrolyte exhibits significant enhancements in ionic conductivity (2.24×10 −4 S cm −1 at 80 °C)and electrochemical stability (up to 6 V vs. Li + /Li). A prototype LiFePO 4 /Li battery with the PEO−LiPFSDI composite electrolyte shows excellent cycling performance with a high reversible capacity of 148 mAh g −1 at a rate of 0.1 C and 135 mAh g −1 at 0.2 C (70 °C), and maintains 100 stable cycles for over 1500 hours.