Dry‐Crafted Charge‐Conductive ZrO _{2 − x} Cathode Shell Coating for High‐Performance Sulfide‐Based Solid‐State Batteries

ABSTRACT Although all‐solid‐state batteries (ASSBs) offer both high energy density and improved safety, the interfacial instability between sulfide‐based solid electrolytes and Ni‐rich layered oxide cathodes results in poor cycling stability. In this study, a charge‐conductive, black ZrO _2−x (BZO _x ) shell coating layer was uniformly applied to single‐crystalline LiNi _0.8 Mn _0.1 Co _0.1 O ₂ (NMC) cathodes using a solvent‐free and dry‐processed mechanofusion method to mitigate the interfacial side reactions of sulfide‐based ASSBs. The BZO _x shell coating layer effectively suppressed unwanted electrolyte decomposition and interfacial degradation while minimizing charge‐transfer resistance. Moreover, BZO _x enhanced both Li ion and electron transport while contributing to interfacial stabilization with the solid electrolyte. Compared to pristine NMC and NMC coated with stoichiometric white ZrO ₂ , BZO _x ‐coated NMC exhibited improved cycling stability with higher coulombic efficiency and reduced voltage hysteresis. Our dry‐crafted cathode coating strategy using charge‐conductive and durable ZrO _2−x materials provides an effective pathway for enhancing the long‐term operation stability of ASSBs.