Suppressed Water Reactivity by Zincophilic-Hydrophobic Electrolyte Additive for Superior Aqueous Zn Metal Batteries

As one of the most promising anodes of aqueous batteries, Zn metal faces uncontrollable side reactions and deleterious dendrite growth, which drastically compromise its cycle life and Coulombic efficiency (CE). To tackle these issues, a versatile electrolyte additive is reported that can regulate the solvation structure, adsorb on the Zn surface, and in situ generate a novel zincophilic-microhydrophobic interphase to isolate the anode from the reactive water molecules. Benefiting from its triple effects on the water reactivity modulation, the Zn metal anode exhibits excellent reversibility with an ultra-high average CE value of 99.92% at 5 mA cm⁻² in the ZnSO₄ electrolyte system, and the Zn||Zn symmetric cell with ethanesulfonamide additive achieves a long lifespan over 6000 h. The merits of ESA additives are further displayed in the Zn//MnO₂ full cells and Zn ion hybrid capacitors, exhibiting excellent capacity retention of 81.60% at 5 C over 1000 cycles, and a 92.25% capacity retention over 50 000 cycles at 5 A g⁻¹, respectively. What's more, the full cells exhibit outstanding stability of 100% capacity retention after 120 cycles at 0.1 C. This strategy shows a promising alternative for the further development of aqueous Zn metal batteries with low-cost ZnSO₄-based electrolytes.