Fluorinated Interphase Enabled by Lithium Salt-Driven Electrical Double-Layer Modulation for Advanced Zinc Metal Batteries

High-concentration electrolytes show promise in zinc metal batteries, but low zinc salt solubility limits options. This study introduces a highly soluble, reduction-active lithium salt into conventional electrolytes. By modifying the solvation structure and electric double layer, the reversibility of the zinc anode is enhanced. At the cathode, ion absorption on the surface leads to a restructured electric double layer, thereby reducing the dissolution of active materials. With this electrolyte, Zn//Cu half-cells exhibit over 1300 cycle lifespan with an average columbic efficiency of 99.60%. Furthermore, the full-cell with high mass loading (5 mg cm⁻²) NaV₃O₈·1.5 H₂O (NVO) cathode and a low negative-to-positive (N/P) ratio of 3 retains 95% capacity after 250 cycles. Even at −45 °C, the capacity retention of the battery is almost 100% after 500 cycles. This work highlights the potential of high-concentration lithium salts to improve the stability of aqueous zinc batteries by modulating solvation structures and interfacial chemistry.