Crosslinked Polymer‐Brush Electrolytes: An Approach to Safe All‐Solid‐State Lithium Metal Batteries at Room Temperature

Abstract Electric vehicles, intelligent machines, and portable electronics in our daily lives are placing insatiable demand on safe and powerful battery materials that can function at room temperature. Herein, we report an ultrathin and robust solid‐state electrolyte with crosslinked polymer‐brush architecture. On one hand, the highly mobile polymer brushes with a moderate side chain length enable efficient cation solvation and fast ion transport, offering room‐temperature ionic conductivity as high as 0.23 mS cm −1 . On the other hand, incorporation of the inorganic core crosslinker endows the material with enhanced mechanical strength, thermal stability, and fire resistance. As a result, the crosslinked polymer‐brush electrolyte films demonstrate stable lithium electrodeposition and great electrochemical performance in Li/LiFePO 4 cells at 30 °C, providing a promising pathway to next‐generation safe and high‐energy lithium metal batteries.