A Zn(ClO4)2 Electrolyte Enabling Long-Life Zinc Metal Electrodes for Rechargeable Aqueous Zinc Batteries

The degradation or dendrite formation of zinc metal electrodes has shown to limit the cycle life of rechargeable aqueous zinc batteries, and a few anode protection methods are proposed. We herein demonstrate that, except for external protections, a simple design of an electrolyte can effectively promote stable and facile Zn stripping/plating from/on zinc electrodes. By using Zn(ClO4)2 in the aqueous electrolyte, reversible Zn stripping/plating is achieved for over 3000 h at 1 mA cm–2 current density and 1 mA h cm–2 capacity, superior to the conventional ZnSO4 electrolyte. The overpotential is constant within each cycle and only increases slightly with the increase of current densities. The excellent performance is guaranteed by the controlled formation of a Cl– containing layer, which limits continuous side reactions. The Zn(ClO4)2 electrolyte shows anodic stability up to 2.4 V, and excellent electrochemical performance is achieved for an example cell with the VO2 cathode, confirming the applicability of the electrolyte for Zn batteries.