Synergistic bulk and surface engineering via rapid quenching for high-performance Li-rich layered manganese oxide cathodes

Lithium-rich manganese-based cathodes (LRMs) have garnered significant attention as promising candidates for high-energy-density batteries due to their exceptional specific capacity exceeding 300 mAh/g, achieved through synergistic anionic and cationic redox reactions. However, these materials face challenges including oxygen release-induced structural degradation and consequent capacity fading. To address these issues, strategies such as surface modification and bulk phase engineering have been explored. In this study, we developed a facile and cost-effective quenching approach that simultaneously modifies both surface and bulk characteristics. Multi-scale characterization and computational analysis reveal that rapid cooling partially preserves the high-temperature disordered phase in the bulk structure, thereby enhancing the structural stability. Concurrently, Li⁺/H⁺ exchange at the surface forms a robust rock-salt/spinel passivation layer, effectively suppressing oxygen evolution and mitigating interfacial side reactions. This dual modification strategy demonstrates a synergistic stabilization effect. The enhanced oxygen redox activity coexists with the improved structural integrity, leading to superior electrochemical performance. The optimized cathode delivers an initial discharge capacity approaching 307.14 mAh/g at 0.1 C and remarkable cycling stability with 94.12% capacity retention after 200 cycles at 1 C. This study presents a straightforward and economical strategy for concurrent surface–bulk modification, offering valuable insights for designing high-capacity LRM cathodes with extended cycle life.