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 Li 6 PS 5 Cl, 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) LiNiO 2, consisting of surface modification and electrode microstructure engineering. After optimization, the SSB cells were found to deliver high capacities ( q dis ≈ 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 LiNiO 2, 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.