Regulating Zn²⁺ Solvation Shell Through Charge‐Concentrated Anions for High Zn Plating/Stripping Coulombic Efficiency

Abstract

The plating/stripping efficiency of zinc (Zn) is directly related to the efficiency of zinc utilization and cycle stability of the battery, which is affected by factors such as the solvated water‐related hydrogen evolution reaction (HER), Zn corrosion, and dendrite formation. Therefore, creating a weak solvate shell for Zn2+ with reduced solvated water molecules can promote stable deposition and stripping of the zinc anode. In this work, a novel approach using the concentrated charge effect of anions is proposed to remove the solvated water and improve the efficiency of Zn plating/stripping. 3 mol kg−1 (3 m) ZnCl2, Zn(ClO4)2, and Zn(BF4)2 electrolytes are used as the representatives to investigate how anions regulate the solvent shell of zinc ion to achieve high Zn plating/stripping Coulombic efficiency (CE). Computational results show that Cl− has a more concentrated charge compared to ClO4− and BF4−, indicating a stronger interaction with Zn2+. This concentrated charge effect reduces the number of water molecules in Zn2+ solvation structures. Benefiting from weak solvent structure, the average coulomb efficiency, and cycling stability of the Zn─Cu asymmetric cell using ZnCl2 electrolyte is better. Additionally, the Zn‐NaV3O8 full cell of the ZnCl2 electrolyte exhibits good electrochemical performance.