Pressure-Related Challenges and Strategic Approaches in Lithium Metal Sulfide all-Solid-State Batteries

Sulfide solid electrolytes, owing to their high ionic conductivity and excellent plasticity, are considered among the most promising candidates for lithium metal all-solid-state batteries. Nevertheless, practical cell assembly and cycling typically rely on externally applied pressure to secure intimate electrode-electrolyte contact and continuous ion-transport pathways. Pressure governs not only densification and interfacial wetting of the sulfide phase but also the distribution of mechanical stress, local current density, and Li-deposition morphology. While high pressure can suppress interfacial resistance and pore formation, it may simultaneously induce electrolyte fracture, particle pulverization, and accelerated dendrite penetration, posing a critical obstacle to practical implementation. This review analyzes the influence of pressure on structural evolution of sulfide electrolytes, interfacial chemistry, ion-transport behavior, and Li-plating kinetics. Recent advances in mitigating pressure dependence-through interface modification, electrode structural engineering, and flexible or quasi-isostatic loading designs-are systematically summarized. Finally, we highlight that constructing interfaces capable of stable operation under low or even zero applied pressure is essential for the technological transition of sulfide-based solid-state batteries.