Dynamic Reconstruction of the Surface Lattice to Stabilize Lithium Nickel Oxide Cathodes via Molybdenum Modification

Abstract

Cobalt-free, nickel-rich oxides are promising cathode materials with high energy density but suffer from poor reversibility due to unstable surface and anisotropic phase transitions. We report the performance improvement of LiNiO₂ by Mo doping within the bulk and epitaxial growth of Li₄MoO₅ on the surface. Mo-modification exerts multiple effects, including construction of a three-dimensional Li⁺ diffusion channel, reduction in surface reaction activity, and alleviation of structural strain, which collectively enhance Coulombic efficiency and stabilize lattice oxygen up to a charging voltage of 4.8 V. The interdiffusion of Li, Ni, and Mo between the surface Li₄MoO₅ and bulk LiNiO₂ facilitates in situ reconstruction of the surface lattice to form a Mo-rich Li⁺/Ni²⁺ superlattice structure that anchors surface oxygen and promotes liberation of additional Li⁺ from Li₄MoO₅ for charge compensation. This study reveals the dynamic structural changes of Mo-modified LiNiO₂ and proposes strategies to address lithium-loss and structure-instability issues in cycling nickel-rich cathode materials.