Stable zinc anode by regulating the solvated shell and electrode–electrolyte interface with a sodium tartrate additive†

Aqueous zinc-ion batteries (ZIBs) have attracted great research interest for use in large-scale energy storage devices due to their inherent safety, environmental friendliness, and low cost. Unfortunately, dendrite growth and interfacial side reactions during the plating/stripping process triggered by uneven electric field distribution on the surface of the Zn anode seriously hinder the further development of aqueous ZIBs. Here, practical and inexpensive sodium tartrate (STA) is used as an electrolyte additive to construct a stable electrode–electrolyte interface, in which STA adsorbs preferentially on the Zn metal surface, contributing to promoting homogeneous Zn deposition. Moreover, STA interacts more strongly with Zn²⁺, which takes the place of the water molecules in the solvated shell and prevents the development of side reactions. In symmetrical cells and full cells, flat Zn anodes can therefore demonstrate remarkable cycle stability, opening the door for the development of cost-effective and effective electrolyte engineering techniques.

Keywords: Zinc ion battery; Electrolyte additive; Zinc dendrites; Hydrogen evolution reaction; Anode protection.