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) ZnSO 4 /0.2 M ES electrolyte exhibits synergistic regulation effects: (1) ES participates in reconstructing the Zn 2+ 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||NH 4 V 4 O 10 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.