Advanced Polymer Electrolyte with Enhanced Electrochemical Performance for Lithium-Ion Batteries: Effect of Nitrile-Functionalized Ionic Liquid

High-voltage electrode materials are beneficial for developing high-power-density lithium-ion batteries. The anodic voltage stability of electrolytes is a major challenge for high-voltage lithium batteries. Herein, a polysiloxane-based solid polymer electrolyte is fabricated by grafting ionic liquid and poly(ethylene oxide) chains onto flexible polysiloxane backbone. An ionic liquid with a strong electron-withdrawing nitrile group and a positively charged imidazole possesses good resistance against anodic oxidation, which endows the solid polymer electrolyte with a wide electrochemical window. The electrolyte integrates advantages of ionic liquid and poly(ethylene oxide) exhibiting a high ionic conductivity (3.56 × 10–4 S cm–1 at room temperature) and excellent resistance to dendrite growth. In addition, both Li/LiFePO4 and high-voltage Li/LiNi0.5Mn1.5O4 cells with the as-prepared solid polymer electrolyte show excellent cycling performance and superior rate capability at 30 °C. Thus, the modified polysiloxane-based electrolyte is a promising electrolyte candidate for next-generation high-energy-density batteries.