Tailoring the Solvation Structure through Water Soluble Tartaric Acid Additive for Stable Zn Anode

Abstract Aqueous zinc‐ion batteries (AZIBs) with inherent safety, cost‐effectiveness and environmental compatibility have garnered significant attention for large‐scale energy storage. However, AZIBs still suffer from the hydrogen evolution reaction, Zn dendrite and Zn corrosion, which are closely correlated with Zn²⁺ solvation structure. Therefore, designing an optimized Zn²⁺ solvation structure with reduced water molecules in the solvation shell is expected to achieve stable and reversible Zn²⁺ plating/stripping. In this study, water‐soluble Tartaric Acid containing abundant ─COOH groups as electrolyte additive for AZIBs is employed. The dissociated ─COOH can replace water molecules around Zn²⁺, leading to a restructured solvation shell, which not only inhibits side reactions, but also enhances the kinetics of de‐solvation process, promoting the formation of a flat and dense zinc deposition layer. The as‐prepared Zn electrode exhibits an impressive areal capacity of 28.21 mAh cm⁻² after resting 6 h and excellent long‐term stability (800 cycles with capacity retention of 81.76%). In addition, in situ microscope and in situ electrochemical impedance spectroscopy (EIS) synergistically identify the outstanding structural stability and enhanced kinetics, respectively. This work sheds light on constructing a highly reversible Zn anode in the seawater‐based electrolyte for AZIBs.