Impact of high-temperature storage on capacity fading of Ni-rich cathodes in sulfide-based all-solid-state batteries

Despite the extensive research efforts focused on enhancing the lifespan and energy density of all-solid-state batteries, the calendar aging behavior of cathodes within the all-solid-state batteries system continues to be underexplored. In this study, we elucidate the capacity fading of Ni-rich cathodes in sulfide-based all-solid-state batteries after high-temperature storage using electrochemical techniques, synchrotron X-ray-based characterization tools, and electron microscopy. High-temperature storage negatively affects the electrochemical performance of Ni-rich cathodes, limiting their charge and discharge capacities, notably charge fading. The underlying cause of capacity fading lies in interfacial side reactions between Ni-rich cathode materials and solid electrolytes. The LiNbO₃ coating layer is found to be effective in preventing interfacial degradation, which virtually eliminates charge and discharge fading. These findings offer a deeper understanding of the capacity fading of Ni-rich cathodes in sulfide-based all-solid-state battery systems during high-temperature storage. Furthermore, they provide insights for achieving all-solid-state batteries with high thermal durability and energy density.