Interface and Electrode Microstructure Engineering for Optimizing Performance of the LiNiO₂ Cathode in All-Solid-State Batteries

Solid-state batteries (SSBs) utilizing superionic thiophosphate solid electrolytes (SEs), such as argyrodite Li6PS5Cl, are attracting great interest as a potential solution for safe, high-energy-density electrochemical energy storage. However, the development of high-capacity cathodes remains a major challenge. Herein, we present an effective design strategy to improve the cyclability of the layered Co-free oxide cathode active material (CAM) LiNiO2, consisting of surface modification and electrode microstructure engineering. After optimization, the SSB cells were found to deliver high capacities (q(dis) approximate to 200 mAh/g(CAM)) and to cycle stably for hundreds of hours. A combination of operando and ex situ characterization techniques was employed to reveal the mechanism of optimization in overcoming several issues of LiNiO2, including poor SE compatibility, outgassing, and state-of-charge heterogeneity. Tailoring the microstructure of the composite cathode and increasing the CAM|SE interface stability enable superior electrochemical performance.