Electro-Chemo-Mechanical Coupling in All-Solid-State Lithium Metal Batteries: From Stress Generation to Failure Mitigation

All-solid-state lithium metal batteries (ASSLMBs) promise enhanced safety and high energy density, yet their solid–solid interfaces create mechanical constraints absent from conventional liquid-electrolyte cells. Electrochemical reactions, ion transport, and interfacial reactions generate lattice strain, volume change, and heterogeneous stress; in turn, stress redistributes ionic and electronic transport, reaction kinetics, and local current density. This bidirectional electro-chemo-mechanical coupling drives particle cracking, interfacial debonding, contact loss, void formation, lithium-filament penetration, and ultimately capacity decay or short circuiting. In this review, we establish a multiscale framework connecting the origins of stress to electrochemical consequences and failure across the crystal, particle, electrode, interface, and cell levels. We critically examine cathode deformation, lithium plating and stripping, stack-pressure evolution, thermal mismatch, and defect-assisted fracture, together with operando imaging, stress sensing, and multiphysics modeling approaches used to resolve these processes. We further assess mitigation strategies based on low-strain electrodes, mechanically compatible composite cathodes, defect-tolerant solid electrolytes, adaptive interphases, regulated stack pressure, and cell architecture. Finally, we identify the need for quantitative failure criteria, multimodal operando characterization, and standardized testing under practical conditions to accelerate durable, high-energy ASSLMBs.