Influence of the slurry composition on thin-film components for the wet coating process of sulfide-based all-solid-state batteries

Sulfide-based all-solid-state batteries are one of the most promising next-generation energy storage systems. Especially the chlorine-rich argyrodite Li₆PS₅Cl (LPSCl) and the ceramic sulfide Li₇P₃S₁₁ (LPS) are attractive solid electrolyte materials due to their high ionic conductivity. To date, research has focused primarily on material chemistry and cell design on a laboratory scale. From a production science point of view, process parameter studies and process engineering are rarely addressed. To fabricate a thin-film separator or composite cathode sheet, wet coating techniques from conventional lithium-ion battery production can be adapted. Therefore, this process study presents interdependencies for the upscaling of thin-film and large-scale sheets. LPSCl and LPS separators with thicknesses down to 40 μm as well as composite cathodes containing the sulfidic solid electrolyte are coated and analyzed. In addition, relevant parameters such as viscosities and coating velocities are varied to quantify interdependencies. The results show, that depending on the solid electrolyte, slurry properties can be adapted and qualified for the wet coating process via doctor blade approaching the way for the industrial roll-to-roll coating process.