Dimensional Strategies for Bridging the Research Gap between Lab‐Scale and Potentially Practical All‐Solid‐State Batteries: The Role of Sulfide Solid Electrolyte Films

The absence of liquid components in all‐solid‐state batteries (ASSBs) based on sulfide solid electrolytes (SSEs) significantly impacts manufacturing processes and performance, particularly concerning mechanical properties and evolution. SSE films play vital roles in this context. This review provides a comprehensive analysis of SSE film design strategies, emphasizing their significance in the cell assembly and operation of practical ASSBs. Essential SSE film components are examined, including SSEs, binders, and scaffold or substrate materials, and key characteristics related to ASSB assembly and operation are addressed, such as conduction properties, electrochemical stability, and mechanical properties. Various SSE films fabricated using different binders and scaffold or substrate materials are explored through slurry‐casting or solvent‐free methods, and ASSBs employing SSE films with diverse form factors and components are presented, emphasizing their ability to operate under low‐pressure conditions. Additionally, the importance of establishing test protocols for assessing SSE film performance metrics is highlighted and strategies for enabling Li metal anodes are introduced. By deepening the understanding of the electrochemo‐mechanical phenomena and engineering processes in ASSBs, it is anticipated that the gap between lab‐scale research and practical goals can be bridged through design strategies that leverage the hybridization of various compositions and the immiscible nature of solid‐state materials.