Salt solution etching to construct micro-gullies on the surface of Zn anodes enhances anodes performance in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) have caused significant research attention due to their low redox potential of 0.76 V, high theoretical capacity of 820 mAh g^-1. However, the dendrite growth of zinc anode and the side reactions caused by water seriously affect the cycle life of AZIBs. To solve the above problems, a new method of etching zinc anodes with CuCl₂ salt solution was designed, which the zinc anode was named CZn. The process resulted to a uniformly distributed micro gully morphology on the zinc surface, and providing an increased number of nucleation sites for zinc deposition and reducing local current density. The calculation results of exchange current density and activation energy show that CZn has stronger Zn/Zn²⁺ kinetic effect. At a current density of 5 mA cm^-2 and an area capacity of 5 mAh cm^-2, cycle life of the CZn symmetrical cell can reach 500 h, which is more than seven times that of the raw Zn symmetrical cell. This work proposes a simple method of zinc anode protection, which provides a new idea for zinc metal anode protection.