Solvation Chemistry Modulation by Dual-Aprotic Polar Additives in Aqueous Zinc-Ion Batteries

The commercialization of aqueous zinc-ion batteries (AZIBs) is hindered by Zn dendrite growth and parasitic hydrogen evolution reaction (HER), which can be effectively mitigated by regulating the Zn²⁺ solvation structure. Here, we demonstrate a dual-electrolyte modification strategy by employing two aprotic polar solvents at an optimized ratio to regulate Zn²⁺ desolvation behavior and interfacial deposition kinetics. The incorporation of dual-aprotic polar additives (DHZS) to the electrolyte simultaneously tailored the Zn²⁺ solvation structure, controlled crystallographic deposition orientation, and modulated the Zn-electrolyte interphase chemistry, thereby enabling a highly reversible and stable Zn anode. Electrochemical analyses confirm that the synergistic modulation in the electrical double layer by DHZS leads to uniform Zn deposition and significantly extends the operational lifespan of AZIBs. Consequently, Zn||Zn symmetric cells exhibit an ultralong cycling life exceeding 690 h at 5 mA cm^-2. Additionally, asymmetrical Zn||Cu cells also showed excellent reversibility with the average Coulombic efficiency >99% over 250 cycles, while Zn||V₂O₅ full cell delivers a capacity retention of ∼70% over 1000 cycles at 1 A g^-1. Overall, the cooperative effect of dual electrolyte additives enables a uniform Zn deposition, suppresses corrosion, and enhances Zn²⁺ transport, providing an effective electrolyte engineering strategy for high-durability AZIBs.