Adjusting the Coordination and Deposition Environment of Zinc Ions to Stabilize the Zn Anode

An economical and eco-friendly food sweetener erythritol with abundant hydroxyl groups and suitable site resistance has been added to ZnSO4 electrolytes in aqueous Zn ion batteries (AZIBs). Density functional theory (DFT) calculations demonstrate that the O atoms in erythritol molecules can supply electrons to Zn2+, thus mitigating an electron transfer from H2O to Zn2+, resulting in erythritol entering the solvation structure of Zn[(H2O)6]2+ and replacing some water molecules. Spectroscopic analysis confirms the altered solvation structure of Zn2+ and the reconstructed hydrogen-bonding network of the ZnSO4 and erythritol electrolytes. With an equilibrium between “network water” and “free water” induced by erythritol additives, the possibility of active water decomposition is degraded, which further inhibits water-splitting and corrosion side reactions. In addition, theoretical studies and experimental characterizations verify that erythritol additives preferentially adsorb on the surface of Zn anodes, thus effectively protecting Zn anodes and inhibiting the mad growth of dendrites. As a result, the cells with ZnSO4 + erythritol electrolytes demonstrated significantly higher Coulombic efficiency values and longer lifetimes than those of pure ZnSO4 electrolytes. This study could advance the research process of small-molecule polyol additives for AZIBs.