The mechanical properties of solid sulfur electrolytes: a local approach for a multiscale design

Optimizing solid-state cathodes and electrolytes requires meeting stringent mechanical constraints, which demands precise knowledge of individual component properties. We show that fast, low-load nanoindentation effectively characterizes single particles in air-sensitive solid electrolytes, overcoming atmospheric control challenges. As a case study, argyrodite (Li 6 PS 5 Cl) pellets were fabricated under varying compaction pressures and particle sizes. Local-scale measurements reveal that smaller or softer particles achieve higher density and smoother surfaces at lower pressures, linking particle-scale mechanics to bulk behavior. These results rationalize macroscopic pellet density and surface quality, providing practical guidance for compaction optimization. Overall, this accessible methodology offers a multiscale framework for designing high-density, high-performance solid electrolytes, enabling informed choices of particle size, compaction pressure, and material properties to enhance the mechanical and electrochemical performance of solid-state batteries.