Zn@C Core–Shell Nanocomposite for Rechargeable Aqueous Zn//MnO2 Batteries with Long Lifetime

Rechargeable zinc-based aqueous batteries are a promising candidate for next-generation energy storage devices because of the high theoretical energy density of Zn as well as the availability, safety, and cheap price of Zn-based aqueous batteries. A Zn@C core–shell composite is designed to overcome two problems of Zn anodes, that is, the formation of Zn dendrites and the corrosion/loss of Zn anode during the charge–discharge process, influencing the lifetime of Zn-based aqueous batteries. The prepared Zn@C composite from ZnO@C with electrochemical reduction is robust as the anode for a Zn@C//MnO 2 battery, and a 98.8% retention after 400 cycles is obtained at a discharge rate of 5 C. The specific capacitance of Zn@C//MnO 2 battery can reach 135 mAh g Zn −1 at 3 C, and the energy density of this battery can reach 75.9 Wh Kg −1 . The coated carbon layer on Zn/ZnO plays a role in protecting Zn/ZnO from leaching or corrosion by KOH, so the structure of Zn@C is a key factor in improving the cycling lifetime of Zn-based aqueous batteries.