Ethylene Sulfate Electrolyte Additive Enables Highly Reversible Zn Anodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries are emerging as one of the most promising energy storage systems. However, their practical applications are still hindered by uncontrollable zinc dendrite growth, water-induced zinc corrosion, and parasitic side reactions. Introducing organic additives into electrolytes to reduce water activity is considered a direct and highly promising strategy to address these issues. Herein, a nonflammable electrolyte system based on an ethylene sulfate (ES) additive was designed. The optimized 2.0 mol L^-1 (M) ZnSO₄/0.2 M ES electrolyte exhibits synergistic regulation effects: (1) ES participates in reconstructing the Zn²⁺ solvation structure, and (2) ES significantly influences interfacial reactions on the zinc anode side and effectively suppresses dendrite growth and water-induced side reactions, thereby markedly promoting uniform zinc deposition. Benefiting from the above mechanisms, the electrolyte system delivers excellent electrochemical performance. Zn||Zn symmetric cells achieve stable cycling for 500 h at 1 mA cm^-2/1 mAh cm^-2. Zn||Cu cells maintain a Coulombic efficiency of 98.5% for 200 cycles. More importantly, Zn||NH₄V₄O₁₀ full cells retain 87% of their capacity after 500 cycles at 3 A g^-1 and deliver a high specific capacity of 228 mAh g^-1. This work provides a new strategy for constructing safe and high-performance electrolytes for aqueous zinc-ion batteries.