Solvation Sheath Regulation to Induce Sulfide Solid-Electrolyte Interphase on Zn Metal Anode

Zn metal anode experiences dendritic growth and side reactions in aqueous Zn batteries. ZnS with relatively high ionic conductivity is a suitable solid-electrolyte interphase (SEI) component, and an organic coverage would provide further protection for the underlying Zn. Herein, we reveal that SO42- anions solvating with Zn2+ are more prone to reduction than the nonsolvating ones and thus capable of ZnS generation. Nevertheless, in the conventional ZnSO4 electrolyte, their solvation with Zn2+ is limited by the shielding effect and steric hindrance from solvating water. Accordingly, erythritol (ET) additive with strong H-bonding and chelation abilities is introduced, which weakens water coordination and regulates solvation geometry. The enhanced solvating SO42- together with chelating ET generates the target SEI. As a result, the Zn//Zn symmetric cell reaches a 960 h cycle life at 8.9 mA cm(-2) and 8.9 mAh cm(-2). The ET additive further enables the stable cycling of full cells by suppressing cathode dissolution.