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.