A Fluorine-Free Organic/Inorganic Interphase for Highly Reversible Aqueous Zinc Batteries

Construction of robust solid electrolyte interphases (SEIs) has proved effective in mitigating dendrite growth and side reactions of zinc (Zn) anodes in aqueous electrolytes. Fluorinated SEIs, in particular, have garnered significant attention due to their exceptional electrochemical stability and high Zn²⁺ conductivity. However, the formation of such SEIs typically relies on the use of fluorine (F)-containing precursors, which inadvertently raise environmental and biological concerns because they show high resistance to degradation in natural environments. Herein, we develop an F-free organic/inorganic hybrid SEI for aqueous Zn batteries using a low-cost N-acetyl-D-glucosamine (NAG) electrolyte additive. The NAG additive not only modulates the solvation structure of Zn²⁺ but also preferentially adsorbs on the Zn anode to promote the in situ formation of a robust organic (Zn chelates)/inorganic (ZnS and ZnCO₃) hybrid SEI layer, thereby enhancing Zn²⁺ de-solvation kinetics and Zn plating/stripping reversibility. Consequently, the Zn anode exhibits a long-term cycling over 6500 h at 0.5 mA cm^‒2, a high average Coulombic efficiency of 99.6% at 1 mA cm^‒2, and greatly extended cycling stability in full cells (up to 2000 cycles). Our electrolyte design paves a promising avenue toward practical Zn batteries that combine performance, cost-effectiveness, and eco-friendliness.