Mechanically, Thermally, and Interfacially Robust Solid Polymer Electrolytes Enabled by an Organic-Inorganic...

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.