Stepwise Screening Process for Further Dopant of NCM811 Cathode Material to Enhance the Reliability of Lithium–Ion Batteries

High-nickel layered oxide materials have become some of the most important cathode materials for lithium–ion batteries (LIBs). Despite their high capacity, they also intensify safety concerns, resulting in reduced reliability of LIBs. Hence, NCM811 was developed to stabilize the structure, enhance reliability, and ensure a high energy density. Herein, we proposed a new criterion for assessing the reliability of LIBs, focusing on lattice distortion, oxygen evolution, and cation mixing of NCM811 under high voltage and elevated temperature conditions. To validate the evaluation criteria, NCM811 was further doped, with the optimal dopant determined through a stepwise pruning process by using density functional theory calculations. Specifically, a consecutive stepwise screening process is implemented for 39 candidate dopants to inspect their validity in reducing lattice distortion and inhibiting oxygen evolution and cation mixing. Furthermore, the role of dopants is examined through electronic structure analysis, highlighting their influence on the materials. Our work not only puts forward a paradigm for the highly effective screening of dopants in NCM811 materials but also clarifies the role of dopants and provides valuable insights for improving the reliability of LIBs.