Since the discovery of its electrochemical activity, Li-excess disordered rock-salt (DRX) cathode material has received worldwide attention as it sets up a new way to exploit oxygen redox beyond the conventional layered structure with late-3d transition metals. However, the intricate structure-function relationship in the disordered lattice of the DRX material fogs the researcher's lens on the underlying redox mechanisms. In this study, we employ a synergistic approach combining neutron total scattering with reverse Monte Carlo modeling and density functional theory calculations to unravel the landscape of oxygen redox reactions in DRX. Redox activities are evaluated in diverse oxygen clusters (OLi_xTM_6−x) and the spatial distribution of these clusters in the model DRX structure (Li_1.16Ti_0.37Ni_0.37Nb_0.1O₂ and Li_1.2Ti_0.35Ni_0.35Nb_0.1O_1.8F_0.2) is explicitly determined. The results unveil that by regulating the short-range ordering between cations, fluorine atoms can effectively decouple the location of Li extraction and electron depletion. Such disentanglement between the Li reservoir and electron reservoir in the DRX lattice could play a pivotal role in protecting the oxidized oxygen and preserving the lattice framework during cycling. Through a tentatively designed non-fluorinated DRX oxide realizing similar Li-electron decoupling, an obvious enhancement of the cycling capability can be achieved without compromising the capacity release.

中文翻译：

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结构调节诱导的锂电子解缠结稳定过量锂无序岩盐正极材料的氧氧化还原


自从发现其电化学活性以来，过量锂无序岩盐（DRX）正极材料受到了全世界的关注，因为它建立了一种超越传统的后3d过渡金属层状结构来利用氧氧化还原的新方法。然而，DRX 材料的无序晶格中复杂的结构-功能关系使研究人员对潜在的氧化还原机制的认识变得模糊。在这项研究中，我们采用中子总散射与反向蒙特卡罗建模和密度泛函理论计算相结合的协同方法来揭示 DRX 中氧氧化还原反应的情况。在不同的氧簇 (OLi _x TM _6−x ) 中评估氧化还原活性以及这些簇在模型 DRX 结构中的空间分布 (Li _1.16 Ti _0.37 Ni _0.37 Nb _0.1 O ₂ 和 Li _1.2 Ti _0.35 Ni _0.35 Nb _0.1 O _1.8 F _0.2 ) 是明确确定的。结果表明，通过调节阳离子之间的短程有序，氟原子可以有效地解耦锂脱嵌和电子耗尽的位置。 DRX晶格中锂库和电子库之间的这种解开可以在循环过程中保护氧化氧和保持晶格框架方面发挥关键作用。通过初步设计的非氟化DRX氧化物实现类似的锂电子解耦，可以在不影响容量释放的情况下实现循环能力的明显增强。