Impact of Extrusion and Direct Calendering on Dry-Coated Cathodes for Sulfidic All-Solid-State Batteries

This study presents a novel dry-coating process for the scalable production of sulfidic ASSB cathodes within a dry room environment. Composite powders, consisting of 82.0 wt% NCM85 and 0.5 wt% PTFE, are mixed and fibrillated using a twin-screw extruder. Dry-coated cathode films are manufactured using a two-roll calender through a single high-shear calendering step. The study explores the impact of processing parameters on the morphology of electrodes and cell performance. Furthermore, the findings are compared to a slurry reference. Increasing the process temperature and reducing the line load enhances PTFE fibrillation and mitigates CAM particle cracking. These adjustments improve electrode homogeneity, density, and CAM-SE interface contact. The improvements are attributed to the deformation of LPSCl particles under shear stress, especially at higher temperatures. XPS analysis reveals temperature-driven degradation of LPSCl, forming Li2S. Despite lower electronic conductivity, dry-coated cathodes exhibit superior ionic conductivity compared to the slurry reference. Single-layer pouch cells with dry-coated cathodes demonstrate enhanced initial capacity, ICE, and discharge rate capability. Optimal performance is achieved with electrodes produced with high extrusion temperature (100°C), medium calender temperature (60°C), and low line load (50 N mm-1).