Abstract: Lithium-rich manganese-based cathodes (R-LNCM) are potential candidates for next-generation Li⁺ batteries. However, their practical applications have impeded by the substantial voltage attenuation on cycling. The irreversible evolution of oxygen triggers transition-metal (TM) migration and structural rearrangements, resulting in the voltage decay. Herein, a linkage-functionalized modification approach to tackle these challenges. The strategy involves the synchronous formation of an amorphous CuO coating, inner spinel structure, and oxygen vacancies on the surface of R-LNCM microspheres, effectively stabilizing the lattice oxygen evolution and suppressing structural distortion. Importantly, this three-in-one surface engineering approach is characterized by its environment-friendly attributes, cost-efficiency and seamless scalability. The corresponding cathode delivers a high specific capacity 298.2 mAh g^-1 with initial coulombic efficiency (ICE) 95.18% at 0.1 C. The voltage decay and the capacity retention rate are 1.70 mV cycle^-1 and 90.5% after 200 cycles at 1 C. The density functional theory shows that the diffusion energy barrier of Li⁺ in Li₂MnO₃ can be reduced by introducing vacancy. Moreover, the introduction of spinel structure in R-LNCM material improves the stability and diffusion ability of R-LNCM. Therefore, the novel insight and method have a potential to make a significantly contribution to the commercialization of R-LNCM for high energy density batteries.

Key words: Lithium-rich manganese-based cathodes, Surface modification, Spinel structure, Oxygen vacancies, Linkage-functionalized