Dendrite-free and stable Zn metal anodes with ZnO protective layer

Metallic Zn can be used as an anode for aqueous zinc-ion batteries due to its low redox potential, rich resources, and high theoretical capacity. However, its practical application is limited by dendrite growth and side reactions. Herein, a simple in-situ growth strategy was applied to fabricate a Zn anode with a ZnO protective layer (Zn/ZnO) to lengthen the cycle life and inhibit the dendrite growth and side reactions. At 1 mA h cm−2 capacity, Zn/ZnO exhibits long-time stability (2500 h) at 1 mA cm−2 and outstanding rate capability (1000 h at 10 mA cm−2) in symmetrical cells. Furthermore, the average coulombic efficiency of the Zn/ZnO//Ti cell is 99.4%, which is desirable at 5 mA cm−2. In addition, the Zn/ZnO//MnO2 cell can maintain a specific capacity of 167.2 mA h g−1 after 800 stable cycles. This work presents a simple fabrication method for Zn anode with excellent performance and suggests the huge possibilities of implementing practically rechargeable aqueous zinc-ion batteries.