Simultaneous regulation of the solvation shell and electrode interface via a multifunctional and low-cost additive enabling long-life aqueous Zn metal batteries

Abstract

Zinc metal batteries have great potential for energy storage applications in smart grids. However, the Zn metal anode presents significant challenges, such as the irrepressible growth of zinc dendrites on the anode’s surface, the accumulation of inert products, and the hydrogen evolution reaction. These issues can lead to the decreased cycling stability of the anode. To solve these problems, we developed a method of adding sodium p-toluenesulfonate to the electrolyte to protect the zinc metal anode. Density functional theory calculations show that the −SO3 functional group in sodium p-toluenesulfonate can alter the solvation structure of Zn2+ and adsorb onto the surface of the Zn metal anode. Thus, the Zn||Zn symmetric cell could be cycled stably for over 2000 h, whereas the Zn||Cu half-cell could be cycled stably for over 5000 cycles, with an average Coulombic efficiency of 99.87 %. The Zn||I2 full cell could be cycled stably for 10,000 cycles under test conditions of 1A/g, and the capacity retention rate was 95.49 %. This study provides insights into the use of additives in the electrolytes of zinc metal batteries.