Bifunctional Ion Rectification Layer Separators Toward Superior Reversible Dendrite‐Free Zinc Metal Anodes

Abstract The slow transport dynamics and poor dendritic growth significantly hinder the performance of zinc metal batteries. Here, a unique difunctional ion rectification strategy is developed using vacuum evaporation technology to design a coated separator for efficient ion transport. The highly conductive Cu‐coated separator acts as an ion redistributor, ensuring homogenized electric field distribution. The excellent znophilicity of the copper coating acts as an ion accelerator, promoting ion transport and facilitating face‐to‐face zinc deposition on the separator. Consequently, this synergy enables stable battery operation at high current densities (cumulative capacity up to 10 800 mAh cm −2 at 8 mA cm −2 ) and high depth of discharge (over 200 h at 94% DOD). The Cu‐coated separator exhibits a reversible plating/stripping life of over 2400 h with an average coulombic efficiency of 99.88%. Notably, the Cu‐coated separator significantly enhances the rate performance and cycle capacity of Zn||V 6 O 13 and Zn||MnO 2 full cells. This functional separator with a difunctional ion rectification strategy presents a promising solution to the challenge of zinc metal anodes.