Mechanically, Thermally, and Interfacially Robust Solid Polymer Electrolytes Enabled by an Organic–Inorganic Interwoven Architecture

Abstract

ABSTRACT Solid polymer electrolytes (SPEs) are promising for use in high‐energy‐density solid‐state Li metal batteries. However, their practical application is hindered by challenges including poor mechanical strength, inadequate thermal stability, electrode‐interface instability, and sluggish ionic transport, which collectively fall short of the required safety and performance standards. Here, we develop an organic–inorganic interwoven architecture using PBO nanofiber and MXene nanosheets as a multifunctional host for SPE. This interwoven framework enhances the mechanical strength and toughness of the solid electrolyte by 12.5‐ and 7‐fold, respectively, and reduces thermal shrinkage below 10% at 200°C. More importantly, we demonstrate that the interwoven structure promotes Li salt dissociation through strong local electric‐field polarization, accelerates Li‐ion transport (0.75 mS cm −1 ), and enhances the stability (8000 h without short‐circuiting) of the Li metal interface during battery operation while suppressing exothermic side reactions under extreme thermal runaway conditions. Using this strategy, solid‐state Li metal pouch cells operate stably under mechanical and thermal abuse conditions, delivering 91.7% capacity retention after 300 cycles at 10C and 90°C. This work effectively addresses the interrelated challenges of mechanical strength, ion transport, and interface/thermal stability of SPE, offering a promising strategy for safe and high‐performance solid‐state Li metal batteries.