Surface Functionalization of LiNi7.0Co0.15Mn0.15O2 with Fumed Li2ZrO3 via a Cost-Effective Dry‐Coating Process for Enhanced Performance in Solid‐State Batteries

Applying a thin film coating is a vital strategy to enhance long term and interface stability of Ni-rich layered oxide cathode materials (NRLOs), especially when they are matched with sulfidic solid electrolytes (SSEs) in solid-state batteries (SSBs). The coating prevents direct contact between the cathode active material (CAM) and the SSE, shielding against parasitic side reactions at the cathode electrolyte interface (CEI). Conventional coatings are based on wet-chemical methods and therefore harmful to the environment and require long-lasting processing and high costs. In this study, we present a versatile, facile and highly-scalable dry-coating method (with suitable equipment up to 500 kg per batch) successfully employed for both multi- and single-crystalline LiNi0.70Mn0.15Co0.15O2 (NCM70) particles by fumed Li2ZrO3 nanostructured particles (LZONPs) via high intensity mixing process. The resulting porous coating layer stays firmly attached at the CAM particle surface without a need of post-calcination step at elevated temperatures. The electrochemical testing results signify enhanced rate capability up to 1.5 mA cm(-2) for both particle types and cyclic stability up to 650 cycles with a capacity retention of 86.1 % for single-crystalline NCM70. We attribute the enhanced performance to the reduced CEI reactions as cathodic charge transfer resistance depressed significantly after dry-coating by LZONPs, being an important step towards sulfidic solid-state batteries.