A self-regulated interface toward highly reversible aqueous zinc batteries

Abstract

Aqueous zinc batteries, that demonstrate high safety and low cost, are considered promising candidates for large-scale energy storage. However, Zn anodes suffer from rapid performance deterioration due to the severe Zn dendrite growth and side reactions. Herein, with a low-cost ammonium acetate (NH₄OAc) additive, a self-regulated Zn/electrolyte interface is built to address these problems. The NH₄⁺ induces a dynamic electrostatic shielding layer around the abrupt Zn protuberance to make the Zn deposition uniform, and the OAc⁻ acts as an interfacial pH buffer to suppress the proton-induced side reactions and the precipitation of insoluble by-products. As a result, in the electrolyte with the NH₄OAc additive, Zn anodes exhibit a long cycling stability of 3500 h at 1 mA cm⁻², an impressive cumulative areal capacity of 5000 mAh cm⁻² at 10 mA cm⁻², and a high Coulombic efficiency of ≈99.7%. A prototype full cell coupled with a NH₄V₄O₁₀ cathode performs much better in terms of capacity retention than the additive-free case. The findings pave the way for developing practical Zn batteries.