Regulation of the solvation structure and electrode interface using a succinic acid additive for highly stable aqueous Zn batteries

Abstract

Metallic zinc shows great promise as an anode material in aqueous rechargeable batteries owing to its high theoretical capacity, excellent safety, and low cost. However, the practical utilization of zinc metal anodes faces challenges due to significant side reactions with the aqueous electrolyte and the prevalent growth of dendrites at the interface between the electrode and electrolyte. In this study, succinic acid (SA) has been investigated as a functional additive to tackle these issues. The SA additive can effectively mitigate side reactions and promote the uniform deposition of Zn by reducing the electrostatic potential of the Zn-ion solvation structure and preferentially adsorb on the surface of the Zn anode. Consequently, symmetric Zn//Zn cells with the SA additive exhibit remarkable cycling stability over 650 hours with a depth of discharge of 51%. The asymmetric Zn//Cu cells display a cycling efficiency as high as 99.7% over 1300 cycles at 1 mA cm⁻² and 1 mA h cm⁻². Additionally, compared to the electrolytes without additives, the developed electrolyte with SA shows a significant enhancement in the cycling performance of a Zn–KMnO full cell.