Self-Healing Solid Polymer Electrolyte for Room-Temperature Solid-State Lithium Metal Batteries

Poor room-temperature ionic conductivities and narrow electrochemical stable windows severely hinder the application of conventional poly(ethylene oxide)-based (PEO-based) solid polymer electrolytes (SPEs) for high-energy-density lithium metal batteries (LMBs). Herein, we designed and synthesized a PEO-based self-healing solid polymer electrolyte (SHSPE) via dynamically cross-linked imine bonds for safe, flexible solid LMBs. The constructed dynamic networks endow this SPE with fascinating intrinsic self-healing ability and excellent mechanical properties (extensibility > 500% and stress >130 kPa). More importantly, this SHSPE exhibits ultrahigh ionic conductivity (7.48 × 10^-4 S cm^-1 at 25 °C) and wide ESW (5.0 V vs Li/Li⁺). As a result, Li||Li symmetrical cells with the SHSPE showed reliable stability in a >1200 h cycling test under room temperature. The assembled Li|SHSPE|LiFePO₄ cell maintained a discharge capacity of 126.4 mAh g^-1 after 300 cycles (0.1C, 27 °C). This work highlights a promising strategy for next-generation room-temperature solid-state LMBs.