Deciphering\nthe Interfacial Li-Ion Migration Kinetics\nof Ni-Rich Cathodes in Sulfide-Based All-Solid-State Batteries

Nickel-rich\nlayered oxide with high reversible capacity and high\nworking potentials is a prevailing cathode for high-energy-density\nall-solid-state lithium batteries (ASSLBs). However, compared to the\nliquid battery system, ASSLBs suffer from poor Li-ion migration kinetics,\nsevere side reactions, and undesired formation of space charge layers,\nwhich result in restricted capacity release and limited rate capability.\nIn this work, we reveal that the capacity loss lies in the H2–H3\nphase transition period, and we propose that the inconsistent interfacial\nLi-ion migration is the arch-criminal. We introduce Si doping to stabilize\nthe bulk structure and Li<sub>4</sub>SiO<sub>4</sub> fast ionic conductor\ncoating to regulate the interfacial behaviors between the Ni-rich\ncathode and sulfide-based solid electrolyte Li<sub>6</sub>PS<sub>5</sub>Cl. The modified NCM@LSO-2||LPSCl||Li–In ASSLBs deliver a\nhigh reversible capacity of 183.5 mA h g<sup>–1</sup> at 0.1C,\n30.3% higher than the bare NCM811 electrode. Besides, the interfacial\nregulation strategy enables the operation at a high rate of 5.0C and\nachieves a high capacity retention ratio of ∼85.8% after 500\ncycles at 1.0C. Furthermore, the underlying mechanisms are well investigated\nthrough kinetic analyses and theoretical simulations. This work provides\nan in-depth understanding on the interfacial degradations between\nNi-rich cathodes and sulfide-based all-solid-state electrolytes from\nthe view of kinetic limitations and offers potential solutions.