Achieving a balance of rapid Zn2+ desolvation and hydrogen evolution reaction inertia on the interface of Zn anode by hydrophilic transition metal oxides

Abstract

It is difficult to achieve fast kinetics of Zn2+(H2O)6 desolvation as well as HER inertia on the same electrolyte/Zn interface during a 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 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, uniform the Zn2+ nucleation sits and HER inertia. What`s more, Zn corrosion can be significantly inhibited benefiting of this coating layer. The efficiency of aqueous Zn-ion batteries shown a great enhancement. It exhibited ultra-long plating/stripping stability up to 1600 h, and excellent recovery (returning to 0.5 from 20 mA/cm2) for symmetric CeO2@Zn system. A full cell with 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 inhibiting hydrogen evolution reaction, which is important for promoting the practical application of rechargeable Zn batteries.