Zwitterionic poly(ionic liquids)-based polymer electrolytes for Lithium-ion batteries applications

In this study, zwitterionic poly(ionic liquid)-based polymer electrolytes with a network structure are prepared by ultraviolet-irradiation radical polymerization of poly(ethylene glycol) methyl ether acrylate (PEGMEA) and zwitterionic liquids, and poly(ethylene glycol) diacrylate is used as cross-linker. The cross-linked structure endows the electrolytes with high thermal stability and excellent dimensional stability. The abundant ether-oxygen group of PEGMEA provides sufficient sites for the transport of Li + and a high ionic conductivity of 0.20 × 10 −3 S cm −1 . The electrolyte shows a high lithium-ion transference number of 0.78, owing to the excellent dissociation ability of zwitterionic liquids towards lithium salts. The lithium symmetric battery can maintain a voltage polarization of 150 mV at 0.1 mA cm −2 over 600 h. The Li/LiFePO 4 battery shows a discharge capacity of 122 mAh g −1 , a capacity retention of 90.0% after 100 cycles, and an average Coulombic efficiency exceeding 99% at 0.1 C, demonstrating strong application potential in lithium-ion batteries.