Long-life cycling aqueous zinc-ion batteries based on g-C3N4@Zn electrodes

Stable Zn anodes with high coulombic efficiency is important for the development of safe, low-cost and environmentally friendly aqueous zinc-ion batteries (AZIBs). However, the performance of Zn anode in AZIBs is deteriorated by its dendrite growth, the corrosion caused by irreversible hydrogen precipitation, and the side reactions occurring during the charge-discharge process. The coating of protective layers on Zn anodes is one of the feasible strategies to overcome these drawbacks. Herein, we coated the chemically stable graphite-phase carbon nitride (g-C3N4) nanosheets on Zn anodes and well overcome its aggregation to create a homogeneous g-C3N4 layer. This g-C3N4 layer possesses a porous structure and abundant active sites favoring the homogeneous deposition of Zn. At the current density of 5 mA cm- 2, the g-C3N4@Zn electrodes provide an ultra-long cycle life over 1300 h. The full-cells assembled with MnO2 also exhibit excellent discharge capability and capacity retention. This study advances the application of carbon-related nanomaterials as protective coating layers for Zn anodes, which may further facilitate the exploitation on aqueous energy storage systems.