Oxygen Release in Ni‐rich Layered Cathode for Lithium‐ion Batteries: Mechanisms and Mitigating Strategies

Abstract LiNi x Co y Al z O 2 (NCA) and LiNi x Co y Mn z O 2 (NCM) have become extensively utilized as cathodes in lithium‐ion batteries for consumer electronics, electric vehicles, and energy storage applications that necessitate consistent power output over prolonged periods and under varying environmental conditions. A crucial structural degradation issue leading to cycling‐induced deterioration, rapid loss of cell capacity/voltage, and the onset of undesirable thermal runaway events involves the decay of cathode materials enriched in nickel. This contribution offers a comprehensive evaluation of cutting‐edge strategies in engineering and material design to enhance the structural stability of cathode materials and reduce detrimental oxygen evolution reactions. It also provides the most recent discoveries regarding oxygen release phenomena and associated mechanisms contributing to structural breakdown in high‐nickel cathodes. The primary source of oxygen depletion and the ensuing structural deterioration caused are thoroughly examined. Additionally, the kinetic mechanisms responsible for oxygen loss are scrutinized, and measures to mitigate resulting electrochemical degradation are elaborated. This overview can guide researchers in the development of oxygen‐containing cathode materials in the future, where oxygen leakage is of lesser concern compared to other forms of deterioration.