Aqueous zinc sulfate/choline chloride hybrid electrolyte toward guided zinc-deposition/stripping for Zn-metal batteries

초록

Zinc metal batteries, with inherent safety, environmental sustainability and high theoretical specific capacity, are promising for next-generation energy storage. However, their application is hindered by severe Zn-anode challenges, including uncontrolled dendrite growth, corrosion and detrimental parasitic reactions. Here, guided by the principles of ‘water-in-salt’ electrolytes and deep eutectic solvents, a novel hybrid electrolyte was designed. It contains low-concentration ZnSO4 dissolved in a high-concentration mixture of choline chloride (ChCl, hydrogen-bond acceptor) and water (hydrogen-bond donor). In this electrolyte, Ch+ cations and Cl- anions cooperatively disrupt the water hydrogen-bond network, effectively suppressing free H2O activity, while the nucleophilic Cl- preferentially enters the primary solvation shell of Zn2+ to facilitate [Zn(H2O)6]2+ desolvation. Together with the electrostatic shielding provided by Ch⁺, these effects establish a stable interfacial environment for reversible Zn deposition/stripping. Moreover, unlike conventional deep-eutectic electrolytes, this hybrid system balances moderate viscosity with high ionic conductivity, thereby collectively enhancing interfacial ion-transport kinetics and enabling highly uniform Zn deposition. As a result, the Zn||Zn symmetric cells employing the electrolyte exhibits excellent cycling stability exceeding 2400 h at 0.5 mA cm-2 and 0.5 mAh cm-2. When integrated into Zn||I2 full cells, it further delivers outstanding cycling performance, validating its practical potential for high-performance batteries. © 2026 Elsevier Ltd.

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