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

Abstract

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).