Lithium-excess cation-disordered rock-salt oxides (DRXs) are investigated intensively as cathode materials for future lithium-ion batteries combining cationic and anionic redox reactions. However, the lattice oxygen redox can cause severe oxygen release resulting in rapid capacity fading. Here, we investigate a series of xLi₂TiO₃-(1 - x)LiMnO₂ (0 ≤ x ≤1) materials and find that only Li_1.2Mn_0.4Ti_0.4O₂ (x = 0.4) and Li_1.1Mn_0.7Ti_0.2O₂ (x= 0.2) can form phase-pure DRXs, which both deliver high capacity (> 250 mAh g⁻¹). The newly discovered Li_1.1Mn_0.7Ti_0.2O₂ DRX exhibits remarkably high capacity retention of 84.4% after 20 cycles compared to only 60.8% for Li_1.2Mn_0.4Ti_0.4O₂. Our result indicates that the irreversible oxygen loss is reduced by raising the Mn content. Theoretical calculations further reveal that increasing the redox-active Mn content from Li_1.2Mn_0.4Ti_0.4O₂ to Li_1.1Mn_0.7Ti_0.2O₂ causes the orbitals near the Fermi level to change from O 2p non-bonding (LiOLi unhybridized orbitals) to (MnO)* antibonding bands, exhibiting a high OO aggregation barrier, preventing O₂ release and resulting in sustained capacity retention. Hence, these new findings demonstrate that regulating oxygen redox by tailoring the redox-active transition metal content is an effective strategy to enhance the cycling stability of DRXs.

锂过量的阳离子无序岩盐氧化物（DRX）作为未来结合阳离子和阴离子氧化还原反应的锂离子电池的正极材料得到了深入研究。然而，晶格氧氧化还原会导致严重的氧释放，导致容量快速衰减。在这里，我们研究了一系列 xLi ₂ TiO ₃ -(1 - x)LiMnO ₂ (0 ≤ x ≤1) 材料，发现只有 Li _1.2 Mn _0.4 Ti _0.4 O ₂ (x = 0.4) 和 Li _1.1 Mn _0.7 Ti _0.2 O ₂ (x= 0.2) 可以形成纯相 DRX，它们都提供高容量（> 250 mAh g ^-1）。新发现的 Li _1.1 Mn _0.7 Ti _0.2 O ₂ DRX 在 20 次循环后表现出非常高的容量保持率为 84.4%，而 Li _1.2 Mn _0.4 Ti _0.4 O _{2 的}容量保持率仅为 60.8% 。我们的结果表明，通过提高 Mn 含量可以减少不可逆的氧损失。理论计算进一步表明，氧化还原活性 Mn 含量从 Li _1.2 Mn _0.4 Ti _0.4 O ₂增加到 Li _1.1 Mn _0.7 Ti _0.2 O ₂导致费米能级附近的轨道从 O 2p 非键合（Li O Li 未杂化轨道）变为 (Mn O)* 反键带，表现出高 O O 聚集势垒，阻止 O ₂释放并导致持续的容量保持。因此，这些新发现表明，通过调整氧化还原活性过渡金属含量来调节氧氧化还原是提高 DRX 循环稳定性的有效策略。