Research progress of O2-type lithium-rich manganese-based cathode materials

The anionic-cationic redox mechanism of Li-rich manganese-based cathode materials is capable of providing a high specific capacity of more than 250 mAh g−1, which thus indicates the great application prospects in the field of high-energy-density lithium-ion batteries. Discriminate from traditional O3-type Li-rich Mn-based cathode materials, the unique oxygen-arranged configurations of O2-type Li-rich Mn-based cathode materials exhibit the relatively higher redox reversibility and structural stability. Limits of the influence of irreversible oxygen loss occurring on the material surface, electrolyte oxidation and structural integrity during the cycling process on the initial coulombic efficiency, rate performance and cycling stability, the commercial applications of O2-type Li-rich Mn-based cathode materials have been slacken. This paper mainly summarizes the preparation method, understanding of crystal structure and lithium storage mechanism towards O2-type Li-rich Mn-based cathode materials in recent years, as well as the mechanism and efficacy of modification strategies including structure modulation, inhibition of electrolyte oxidation and mitigation of strain effects upon enhancing the capacity and cycle stability of the materials. In addition, the future research direction of O2-type Li-rich Mn-based cathode materials is prospected to promote the industrial development and application.