Storage Performance and Structure Degradation Mechanism of Single-Crystal Ni-Rich Material

Single-crystal nickel-based ternary cathode materials with many specific failure modes demonstrate a short air storage lifetime, which suppresses their large-scale production. In this work, the evolution and deterioration processes of the electrochemical performance of a single-crystal high nickel cathode material (SCNCM) during storage at room temperature are investigated. The results show that Ni3+ is unstable after contact with air. It is easy to transform from a layered phase to a NiO rock-salt phase on the surface of the SCNCM. The structural transformation causes the precipitation of oxygen and further gives rise to many oxygen vacancies. With increasing storage time, the electrochemical performance of SCNCM decreases precipitously due to the R3̅m structural decay and the occurrence of side reactions. Consequently, the storage procedure of the SCNCM follows a crucial cycle performance and capacity drop pattern. This research is beneficial to optimizing the schedule of SCNCM samples in large-scale production lines and improving the quality of products.