High Performance All-Solid-State Batteries with a Ni-Rich NCM Cathode Coated by Atomic Layer Deposition and Lithium Thiophosphate Solid Electrolyte

Achieving compatibility between cell components is one of the major challenges for the widespread adoption of bulk-type solid-state batteries. In particular, superionic lithium thiophosphate solid electrolytes suffer from oxidation at high voltages when interfaced with state-of-the-art cathode materials. Here, we report on atomic layer deposition (ALD) of conformal HfO2 nanocoatings onto LiNi0.85Co0.10Mn0.05O2 (NCM-851005) cathode material. Based on electrochemical testing in high-loading (pellet-stack) solid-state battery cells, we demonstrate the positive effect of ALD HfO2 coating on the cyclability and stability of NCM-851005. Modification of the coating morphology by postannealing further improved the cycling performance considerably, especially the Coulombic efficiency in the initial cycles and the rate capability. The results demonstrate the ability of ALD to produce high-quality surface films on industrially relevant electrode materials, thus providing a suitable platform for systematic investigations into the functionality of protective coatings in solid-state and other batteries.