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

The development of aqueous zinc metal batteries (AZMBs) is hampered by dendrites and side reactions induced by reactive H2O. 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 Zn2+ 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//V2O5 and Zn//VO2 cells. Particularly, the specific capacity of a Zn//V2O5 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.