Constructing High‐Performance Zn‐Iodine Batteries with CuI‐PVP Composite Layer Coated Zn Anodes

Aqueous zinc‐iodine (Zn‐I2) batteries are promising for large‐scale energy storage due to abundant raw materials, safety, and environmental benefits. However, dendrite growth and side reactions on Zn anodes hinder their practical application. Herein, a copper iodide‐polyvinylpyrrolidone (CuI‐PVP) composite layer is coated onto Zn anodes (i.e., CuI‐PVP@Zn) to protect the interfaces from dendrite growth and hydrogen evolution corrosion. In this coating, the CuI spontaneously reacts with Zn and generates metallic Cu with high zincophilictiy. The resulting Cu, as heterogeneous seeds, can further enhance the Zn deposition uniformity. Moreover, the released iodine from the layer can be oxidized on cathode and contribute additional capacity. Consequently, the symmetric cell with CuI‐PVP@Zn anodes demonstrates a long cycling life of over 1400 hours at 1 mA cm‐2 and 1 mAh cm‐2. Even under a high current density of 5 mA cm‐2 (DOD = 8.56%), the CuI‐PVP@Zn cell still exhibits a long cycling stability of over 660 hours. In Zn‐I2 batteries, adoption of the CuI‐PVP@Zn anode enables a high specific capacity of 251.4 mAh g‐1 at 1 A g‐1 after 2800 cycles.