21:T4a6,Sodium metal is a promising anode for high-energy-density sodium rechargeable batteries (RSBs). However, the low Coulombic efficiency (CE) of the Na plating/stripping process and the problem of safety hinder their practical application. Herein, we report a facile strategy for employing the fluorinated phosphate solvents to realize highly reversible Na plating/stripping and improve the safety performance. The fluorinated phosphate molecules reduce the polarity of the solvent and lower the coordination number to Na⁺, which makes it possible to form the anion-induced ion-solvent-coordinated (AI-ISC) structures with high reduction tolerance. Moreover, the fluorination treatment enhances the oxidation resistance of the phosphate solvent, enabling compatibility with the high-voltage Na₃V₂(PO₄)₂F₃ (NVPF) cathode. As expected, the Na@Al//NVPF full cell with the as-prepared 0.9 M NaFSI/tris(2,2,2-trifluoroethyl) phosphate (TFEP) demonstrates a capacity retention of 83.4% after 200 cycles with an average CE of 99.6%. This work opens a new avenue for designing high-energy-density RSBs with improved safety performance.22:T4f4,Abstract High‐voltage LiCoO 2 (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li‐ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high‐voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li‐PVDF) coating under air atmosphere. Benefitting from the good film‐forming and strong adhesion ability of Li‐PVDF, the thus‐obtained LiF layer is uniform, dense, and conformal; therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high‐voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF‐modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g −1 at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high‐voltage LCO cathodes reported so far.

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