Reassessing anionic redox in conventional layered oxide cathodes for Li-ion batteries: ionic and covalent mechanisms

, which leads to the aggregation of vacancies in the transition metal layer, thereby accelerating structural destabilization. This variation in oxygen dimerization behavior among NCMs is closely correlated with differences in elemental composition, spin states, and stacking faults. Our findings comprehensively reveal the redox behaviors of transition metals and oxygen, particularly highlighting oxygen behavior at each delithiation state, helping to optimize the utilization of oxygen redox reactions in commercial NCM compounds for high-capacity and high-energy-density lithium-ion batteries.