An electrolyte additive for interface regulations of both anode and cathode for aqueous zinc-vanadium oxide batteries

Abstract

Aqueous Zn batteries provide high safety and low cost. However, the Zn metal anode experiences various side reactions and dendritic growth in aqueous electrolytes. Herein, we regulate the interfaces at both Zn anode and vanadium oxide cathode in aqueous batteries with a high donor number electrolyte additive. The N-methylpyrrolidone (NMP) molecule with the donor number of 27.3 is introduced to the ZnSO4 electrolyte at the low concentration of 5 %. It preferentially adsorbs on both electrode surface and induces electrode–electrolyte interfaces composed of mixed organic and inorganic species. Thanks to the effective protection of solid-electrolyte interface (SEI) on Zn anode, the corrosions from electrolytes are inhibited, and 99.5 % coulombic efficiency of plating-stripping is realized. The Zn deposition behavior is also modified, which ensures uniform Zn growth and stable Zn plating-stripping for 1100 h. Meanwhile, the cathode-electrolyte interface (CEI) at the V6O13·H2O cathode effectively suppresses vanadium dissolution, and the capacity retention over cycling is enhanced. Our work presents an effective strategy to simultaneously promote the electrochemical performance of both electrodes in aqueous Zn batteries.