Reducing External Pressure Demands in Solid‐State Lithium Metal Batteries: Multi‐Scale Strategies and Future Pathways

Abstract Solid‐state lithium metal batteries (SSLMBs) are poised to revolutionize energy storage technologies by combining exceptional energy density with inherent safety. Yet, their commercialization faces fundamental challenges: poor solid–solid interfacial contacts, lithium dendrite proliferation, and electro‐chemo‐mechanical failure. This perspective presents a comprehensive analysis of external pressure as a multi‐scale engineering lever for SSLMBs, bridging atomic‐level ion transport, interfacial stabilization, and industrial‐scale device integration with particular emphasis on its dynamic interplay with internal stress. At the atomic scale, applied pressure densifies electrode/electrolyte architectures, optimizes ion‐transport pathways, and mitigates lattice distortion‐induced stresses. Microscopically, it enables intimate interfacial contacts, homogenizes Li deposition stresses to suppress dendrites, and stabilizes interphases. Macro‐scale strategies demonstrate how dynamic pressure coupling through in(ex) situ monitoring and roll‐to‐roll compaction can sustain interfacial integrity in large‐area cells by counterbalancing internal stress evolution. External pressure is positioned as a tunable design parameter that synergizes materials innovation with process engineering to simultaneously enhance electrochemical performance and mechanical resilience. Looking ahead, intelligent pressure‐management systems integrating machine learning‐driven adaptive control, stress‐responsive materials, and operando characterization tools is proposed. These advancements will be pivotal for realizing pressure‐optimized SSLMBs that meet the energy density (>500 Wh kg ⁻¹ ) and cycling stability demands of electric aviation and grid storage, which will accelerate the global transition to sustainable energy.