Fluorination from Surface to Bulk Stabilizing High Nickel Cathode Materials with Outstanding Electrochemical Performance

Abstract

High nickel layered oxides provide high energy densities as cathodes for next‐generation batteries. However, critical issues such as capacity fading and voltage decay, which derive from labile surface reactivity and phase transition, especially under high‐rate high‐voltage conditions, prevent their commercialization. Here we propose a fluorination strategy to simultaneously introduce F atoms into oxygen layer and create a F aggregated interface. Substitution F for O stabilizes the layered ionic framework as the F ions can anchor the internal transition metal ions through strong TM−F bonding interaction, alleviating anisotropic lattice strain accumulation and release during the cycle, and promoting the Li+ dynamics diffusion. Meanwhile, the fluorinated interface induces the formation of a thin and stable CEI, ameliorating the detrimental issues like oxygen vacancy formation, the HF attacks and metal dissolution. The resultant fluorinated cathode delivers a high reversible capacity of 192.9 mAh g−1 at 10 C within the voltage range of 2.7–4.5 V. This fluorination strategy approach provides design concepts for the advanced cathodes that can meet the demands of high‐rate and high‐voltage applications in next‐generation batteries.