Chemo‐Mechanical Failure and Reinforcement of Solid Electrolyte Films for Practical All‐Solid‐State Li Metal Pouch Cells

ABSTRACT All‐solid‐state Li metal batteries (ASLMBs) are the key to achieving high energy densities; however, studies on practically relevant pouch‐type cells remain scarce. A critical challenge lies in integrating thin solid electrolyte films, particularly under the high pressures required for cell assembly, which has been largely overlooked. Here, we reveal the inherent incompatibility of conventional sulfide solid electrolyte films with Li metal during pouch cell assembly. To address this challenge, we introduce a simple yet effective post‐engineering strategy that modifies the chemical interactions between Li 6 PS 5 Cl and nitrile butadiene rubber binders, significantly enhancing the mechanical robustness and Li metal compatibility, even under 450 MPa isostatic pressing. Complementary experimental analyses and finite element method simulations identify the underlying enhancement mech…