Achieving a balance of rapid Zn2+ desolvation and hydrogen evolution reaction inertia at the interface of the Zn anode

Abstract

It is difficult to achieve fast kinetics of Zn²⁺(H₂O)₆ desolvation as well as HER inertia at the same electrolyte/Zn interface during long-term cycling of Zn plating/stripping in aqueous Zn-ion batteries. Herein, an effective interface construction strategy with hydrophilic transition metal oxides was proposed to achieve that balance using a CeO₂ layer coating. The hydrophilic CeO₂ layer can bring a balance between improving the access to the anode surface for Zn²⁺(H₂O)₆ electrolyte ions, providing uniform Zn²⁺ nucleation sites and HER inertia. What's more, Zn corrosion can be significantly inhibited benefiting from this coating layer. The efficiency of aqueous Zn-ion batteries showed a great enhancement. Ultra-long plating/stripping stability up to 1600 h and excellent recovery (returning to 0.5 from 20 mA cm⁻²) for the symmetric CeO₂@Zn system were observed. A full cell with the MnO₂ cathode (CeO₂@Zn//MnO₂) with good reversibility and stability (∼600 cycles) was fabricated for practical application. Our work provides a fundamental understanding and an essential solution to deal with the balance between rapid desolvation and inhibition of the hydrogen evolution reaction, which is important for promoting the practical application of rechargeable Zn batteries.