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

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 Zn 2+ 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 ) ZnCl 2 , Zn(ClO 4 ) 2 , and Zn(BF 4 ) 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 ClO 4 − and BF 4 − , indicating a stronger interaction with Zn 2+ . This concentrated charge effect reduces the number of water molecules in Zn 2+ solvation structures. Benefiting from weak solvent structure, the average coulomb efficiency, and cycling stability of the Zn─Cu asymmetric cell using ZnCl 2 electrolyte is better. Additionally, the Zn-NaV 3 O 8 full cell of the ZnCl 2 electrolyte exhibits good electrochemical performance.