Coupled Regulation of Oxygen-Vacancy-Modified Near-Surface Structure and Interfacial Stability for High-Performance Li-Rich Mn-Based Cathodes

Li-rich Mn-based layered oxides (LRMOs) are prospective next-generation cathodes, delivering high specific capacities via coupled cationic and anionic redox. However, sluggish reaction kinetics, irreversible oxygen loss, and progressive interfacial structural degradation limit the practical application of LRMOs. Herein, a coupled strategy for regulating the near-surface structure and interfacial stability is developed using ammonium titanyl oxalate (ATO) as a multifunctional precursor. During thermal treatment, an approximately 10 nm Li2TiO3 coating layer forms to stabilize the cathode interface. Meanwhile, reducing gases released from precursor decomposition induce oxygen vacancy formation, whereas Ti incorporation suppresses excessive transition-metal (TM) reduction in the near-surface region, thereby alleviating the associated increase in Mn3+ content and Jahn–Teller distortion. Moreover, the coupled Ti and oxygen vacancy configuration enhances anionic redox reversibility, stabilizes the near-surface oxygen framework, and lowers the Li+ migration barrier, thereby improving Li+ transport and structural stability. The optimized ATO-2% cathode achieves an average initial Coulombic efficiency (ICE) of 90.07% at 0.1 C and a capacity retention of 88.1% after 300 cycles at 1 C. This work establishes a coupled regulation strategy for the oxygen vacancy-modified near-surface structure and interfacial stability, providing a route for optimizing oxygen vacancy engineering in LRMO cathodes.