Self‐Standing Highly Conductive Solid Electrolytes Based on Block Copolymers for Rechargeable All‐Solid‐State Lithium‐Metal Batteries

Abstract Solid polymer electrolytes (SPEs) have been emerging as attractive candidates for meeting the demand in safe and high energy density batteries, attributed to their low flammability and ease in process. The architectural design of polymer matrices can improve the physicochemical and electrochemical properties of SPEs, thus leading to an enhanced performance of rechargeable all‐solid‐state lithium metal (Li⁰) batteries (ASSLMBs). However, for the majority of the reported SPEs, high ionic conductivities are achieved at the expense of their mechanical stiffness that is crucial for the processing of ASSLMBs. Herein, we report a new type of self‐standing and highly conductive SPE based on tailor‐made block copolymers, containing highly flexible Jeffamine‐based blocks and mechanically stable polystyrene moieties. The synthesis is facile and “one‐pot”. The electrolytes exhibit good mechanical properties and high ionic conductivities (5.6×10⁻⁴ S cm⁻¹ at 70 °C and 7.9×10⁻⁵ S cm⁻¹ at 40 °C). The superior compatibility with Li⁰ electrode allows the electrolyte to be cycled in a Li⁰||LiFePO₄ cell with good coulombic efficiency and low capacity fading. The tailor‐made block copolymers offer a potential entry to safe and high‐performance ASSLMBs.