Physicochemical Dual‐Force‐Driven PVAC@LPSCl Composite Electrolyte Film for High‐Performance All‐Solid‐State Batteries

The commercialization of sulfide‐based all‐solid‐state lithium batteries is hindered by inherent trade‐offs between electrolyte thickness and mechanical performance in solid‐state electrolyte membranes. This study employs density functional theory to explore binder‐SSE interfaces systematically, identifying polyvinyl acetate (PVAC) with superior interfacial binding energy (ΔE ads = −0.90 eV) via carbonyl‐lithium coordination (Li─O). Based on this, a PVAC‐based composite SSE film (E‐LPSCl1.5) is developed, exhibiting an ultrathin 50 µm thickness, 1.2 MPa tensile strength, and enhanced ionic conductivity (2.80 mS cm −1 ). The film achieves a critical current density of 3.18 mA cm −2 and sustains 1000 h stable Li plating/stripping at 1.27 mA cm −2 . Whole cells deliver 87.30% capacity retention after 200 cycles at 0.5C . Notably, E‐LPSCl1.5‐based pouch cells pass stringent safety tests (180° bending, cutting, puncture) without thermal runaway while maintaining electrochemical functionality. By employing a multiscale research methodology, this work not only pioneers the elucidation of binder‐electrolyte chemical bonding mechanisms at the molecular structure level but also establishes a new paradigm for binder selection in the development of highly stable and safe all‐solid‐state lithium batteries.