High-capacity O3-type lithium-rich manganese-based (LRM) materials exhibit significant structural instability and severe voltage decay, which limit their practical applications. In contrast, the O2-type LRM materials demonstrate remarkable structural stability despite offering lower capacity. In this study, a composite material, O3@O2-LRM is designed, by coating the main structure of O3-type LRM with a minor amount of O2-type LRM to combine the high capacity of the O3 phase with the superior stability of the O2 phase. Electrochemical tests demonstrate that O3@O2-LRM exhibits both high specific capacity and reduced voltage decay. Furthermore, a series of characterizations after different cycles confirm its enhanced structure stability compared to O3-LRM. This novel structure holds great promise for developing advanced cathode materials capable of meeting the demanding requirements of next-generation Li-ion batteries.