Dual Thermal Stabilization Toward Highly Safe and Durable All‐Solid‐State Lithium Metal Batteries Based on Sulfide Electrolytes

The practical deployment of all‐solid‐state lithium (Li) metal batteries (ASSLMBs) based on sulfide electrolytes is constrained by the thermal–electrochemical coupled failure and safety issues under abusive conditions. Here, a dual thermal‐stabilization strategy is identified and rationalized as the optimal choice to tailor above issues. A fluorinated graphene (FG)‐interlayer is introduced to effectively enhance heat dissipation and deflect Li dendrite propagation inside the ASSLMBs, while an oxygen‐vacancy‐rich copper oxide (CuO 1−x ) additive is applied to efficiently capture reactive oxygen species released from charged cathodes and thus mitigate the electrolyte oxidation. As a demonstration model, the as‐modified Li 6 PS 5 Cl (LPSC)‐based full cells achieve stable cycling over 2000 cycles at 1 C with 96% capacity retention, and well retain the room‐temperature capacity even at 90°C. Accelerated rate calorimetry (ARC) tests on pouch cells further demonstrate enhanced thermal stability. This dual‐thermal‐stabilization paradigm can be extended to sulfide/chlorinated oxide bilayer electrolyte systems.