Drying Process of Sulfide‐Based All‐Solid‐State Battery Components—Investigation on Adhesion Strength and Microstructural Changes

Sulfide‐based all‐solid‐state batteries are a promising future cell concept to enhance energy densities and create an advantage in safety aspects in comparison to conventional lithium–ion batteries. To guarantee a high performance of the cells, a pronounced interfacial contact between the single components and a homogeneous microstructure is essential to reduce ionic resistances and enhance mechanical stability. To produce sheets on a large scale, established processes such as mixing, coating, drying, and calendering can be applied. The drying process is the most energy consuming and cost‐intensive process with major influence on the component's microstructure and mechanical properties. As the latter is of particular importance for industry‐relevant manufacturing, this research study focuses on the influence of process and product parameters on prevailing microstructural phenomena and adhesion strength of sulfidic composite cathodes and separators. Results show that the microstructure is changed at temperatures above 50 °C, leading to a significant loss of adhesion strength. Sulfide‐based composite cathodes and solid electrolytes which are fabricated by wet coating, are investigated regarding their microstructural behavior and adhesion strength after applying high‐temperature drying. Both cohesion and adhesion failure are observed for temperatures between 25 and 100 °C.