Water‐Deficient Interface Induced via Hydrated Eutectic Electrolyte with Restrictive Water to Achieve High‐Performance Aqueous Zinc Metal Batteries

Abstract The development of aqueous zinc metal batteries (AZMBs) is hampered by dendrites and side reactions induced by reactive H ₂ O. In this study, a hydrated eutectic electrolyte with restrictive water consisting of zinc trifluoromethanesulfonate (Zn(OTf) ₂ ), 1,3‐propanediol (PDO), and water is developed to improve the stability of the anode/electrolyte interface in AZMBs via the formation of a water‐deficient interface. Additionally, PDO participates in the Zn ²⁺ solvation structure and inhibits the movement of water molecules. PDO also preferentially adsorbs along the Zn (100) plane, thereby inducing the formation of the organic/inorganic SEI layer that enables the cycle life of a Zn//Zn symmetric cell to reach 3000 h at 1 mA cm ⁻² and 1 mAh cm ⁻² . Further, interfacial modulation by the eutectic electrolyte improves the cycling stability of Zn//V ₂ O ₅ and Zn//VO ₂ cells. Particularly, the specific capacity of a Zn//V ₂ O ₅ cell with the eutectic electrolyte is 1.7 times that of a cell with the 2M Zn(OTf) ₂ electrolyte, with a capacity retention of 93% after 100 cycles at 0.5 A g ⁻¹ . This study provides a new perspective on the electrolyte modification strategies for AZMBs, highlighting the potential of PDO‐8 electrolyte in developing aqueous energy storage devices with excellent cycling stability.