Hierarchical Cation Order Enhances Intrinsic Phase Stability in High-Nickel Cathodes with Ultrahigh Initial Coulombic Efficiency

Nickel-rich layered cathodes (e.g., LiNi₀.₇Co₀.₁Mn₀.₂O₂) suffer from interfacial degradation and bulk phase transitions, resulting in capacity fading and structural instability. Conventional doping (e.g., Al, Mg) stabilizes the lattice but often exacerbates cation disorder, while surface coatings (e.g., Al₂O₃, TiO₂) inhibit side reactions without suppressing bulk phase changes. Single-crystal cathodes improve mechanical stability yet remain susceptible to surface degradation. Although integrated doping-coating approaches (e.g., La₂O₃/La) show promise, they often rely on physical mixtures with limited atomic-level control. Here, a multi-tiered cation ordering strategy is reported through precisely designed interlayer (Ga³⁺/Ni²⁺/Li⁺/Ni²⁺) and intralayer (Li⁺/Ga³⁺) arrangements. This ordering suppresses Jahn–Teller distortion, spinel formation, and Li⁺/Ni²⁺ antisite defects, while facilitating Li⁺ transport. The modified cathode exhibits an initial Coulombic efficiency of 94.5% and retains 80% capacity after 430 cycles, with high stability at 4.5 V and 50 °C. This work provides an atomic-level ordering strategy for developing high-energy-density, long-life batteries.