Oxygen vacancy engineering for high-performance Li-rich manganese cathodes: Advances and prospects

Lithium-rich manganese-based cathodes (LRMOs) are the key materials for promoting the commercialization of secondary batteries due to their high specific capacity and energy density. Oxygen vacancies (OVs) in LRMOs, as inherent structural defects in both the surface and bulk phases, provide additional pathways for efficient ion diffusion, significantly enhancing ion conduction efficiency. OVs also provide abundant reactive sites, thereby actively promoting cycle stability and rate performance. Although some adverse effects, such as lattice distortion, structural degradation, and performance degradation, are induced by OVs, these effects can be effectively alleviated or overcome through well-designed strategies. This review discusses the dynamic evolution mechanism and introduction methods of OVs in LRMOs, emphatically analyzing the complex coupling relationship between OVs and other defects in the materials. It is worth mentioning that this paper also systematically introduces the influence of OVs on the properties of the materials and the means of characterizing OVs. These findings not only lay a solid foundation for exploring the internal relationship between their microstructure and macroscopic properties but also provide a valuable theoretical basis for fully exploiting the high specific capacity potential of LRMOs.