Cycling Performance and Limitations of LiNiO₂ in Solid-State Batteries

Solid-state batteries (SSBs) have been touted as the next major milestone for electrochemical energy storage, improving safety and enabling higher energy densities. LiNiO2 (LNO) has long been considered a promising cathode material; however, its commercial implementation is complicated by stability issues, including reactivity toward the electrolyte components. To address this, a detailed study probing the electrochemical behavior of LNO in pellet-stack SSB cells, in combination with argyrodite Li6PS5Cl solid electrolyte (SE) and Li4Ti5O12 anode, is for the first time presented herein. In this configuration, LNO delivers a specific capacity of 105 mAh/gLNO after 60 cycles (0.2C, 45 °C), which was improved considerably to 153 mAh/gLNO by applying a LiNbO3 coating to the material. Using complementary operando and ex situ characterization techniques, contributions to the initial capacity loss and capacity fading could be resolved and attributed to decomposition of the argyrodite SE and to volume changes and gas evolution in LNO.