Solid‐state single‐ion conducting comb‐like siloxane copolymer electrolyte with improved conductivity and electrochemical window for lithium batteries

Achievement of high conductivity and electrochemical window at ambient temperature for an all‐solid polymer electrolyte used in lithium ion batteries is a challenge. Here, we report the synthesis and characterization of a novel solid‐state single‐ion electrolytes based on comb‐like siloxane copolymer with pendant lithium 4‐styrenesulfonyl (perfluorobutylsulfonyl) imide and poly(ethylene glycol). The highly delocalized anionic charges of SO 2 N (–) C 4 F 9 have a weak association with lithium ions, resulting in the increase of mobile lithium ions number. The designed polymer electrolytes possess ultra‐low glass transition temperature in the range from −73 to −54 °C due to the special flexible polysiloxane. Promising electrochemical properties have been obtained, including a remarkably high conductivity of 3.7 × 10 −5 S/cm and electrochemical window of 5.2 V (vs. Li + /Li) at room temperature. A high lithium ion transference number of 0.80, and good compatibility with anode were also observed. These prominent characteristics endow the polymer electrolyte a potential for the application in high safety lithium ion batteries.