High-performance solid polymer electrolytes for lithium ion batteries based on sulfobetaine zwitterion and poly (ethylene oxide) modified polysiloxane

Abstract

Herein we report a new high ionic conductivity and wide electrochemical window solid polymer electrolyte (SPE), which is developed via grafting sulfobetaine zwitterion (ZI) and poly (ethylene oxide) (PEO) chains on highly flexible polysiloxane backbone followed by crosslinking of tri(ethylene glycol) divinyl ether. The synergistic effect of zwitterion and PEO endows the SPE with an excellent ionic conductivity of 3.39 × 10−4 S cm−1 and the wide electrochemical stable window of 5.0 V (vs. Li/Li+) at room temperature. LiFePO4/Li half-cells with as-prepared solid polymer electrolyte present a high initial discharge capacity of 155 mAh g−1 and superior cycle stability with a capacity retention of 93% at 0.1 C after 100 cycles at 30 °C. In addition, LiNi0.5Mn1.5O4/Li half-cells employing such polymer electrolyte also deliver excellent cycle performance and stability. The above results indicate that the designed zwitterionic SPE appears to be a potential candidate for application in all-solid-state lithium-ion batteries.