Mechanofusion-derived cathode composite microstructures with scalable mixed conducting matrix coatings for solid state batteries

Abstract

The successful implementation of solid state batteries not only requires the use of high-capacity anodes, but also high-performance composite cathodes. However, the production of solid state battery cathode composites with optimized microstructures remains a significant challenge, especially for large-scale fabrication. Here, we present a scalable high-intensity dry mixing process to create tailored functional coatings on single-crystalline LiNi0.82Mn0.07Co0.11O2 via mechanofusion. We investigate the coating of LiNi0.82Mn0.07Co0.11O2 with the malleable halide solid electrolyte Li3InCl6 under various process conditions, linking process parameters obtained from discrete element method simulations with experimentally accessible morphological properties to offer guidelines for further optimization. In this way nanometer-thin covering coatings as well as thick matrix coatings are successfully produced. Incorporating carbon black into the thick matrix coating results in well-performing mixed conducting matrices that can be used directly as composite cathodes without further treatment. The compositions investigated enable stable cycling with a specific capacity of up to qcomp = 100 mAh g−1 (based on the total mass of the composite cathode) at a C-rate of 1 C (60 min). While higher carbon black content is observed to improve CAM utilization, excessive amounts are detrimental for cell kinetics and chemo-mechanics, emphasizing the importance of the cathode mixing process and composition on overall cell performance.