Ion flux regulating with Au-modified separator to realize a homogenize Zn metal deposition

Aqueous Zn-ion batteries (AZIBs) have attracted widespread attention owing to the feature of low cost, inherent safety and eco-friendliness. However, the poor reversibility of Zn anode severely hinders the practical applicability of AZIBs. Separator modification is an effective way to functionalize the electrode/electrolyte interface and improve the cycling performance. Here, we propose a modified glass fiber separator with Au coating (Au@GF), which could realize uniform Zn²⁺ distribution at the electrode/electrolyte interface and regulate the plating/stripping behaviors, achieving a dense and homogenous deposition. Zn||Zn symmetric cells assembled with Au@GF separator demonstrate evidently prolonged cycle life over 1600 h at the current density of 5 mA cm^-2 and the capacity of 1 mAh cm^-2, while symmetric cells with GF fail in less than 40 h. Even at the condition of 15 mA cm^-2/3 mAh cm^-2, lifespan of Zn||Zn cells with Au@GF is extended to 750 h, which is more than 3 times compared with that of GF. The modified separator with highly conductive coating is capable of a longtime stable Zn plating/stripping. Moreover, an enhanced cycling performance is also detected in a series of full cells with different cathode materials. This work provides an easy and efficient approach to homogenize Zn²⁺ deposition.