Highly Reversible Zinc Anode Achieved by Surface Polyimide Coating for High‐Performance Aqueous Zinc‐Ion Batteries

Zinc‐ion batteries (ZIBs) are developing rapidly, due to the merits of rich resources, superior security, high theoretical capacity, and attractively low price of zinc anodes. Nevertheless, the growth of zinc dendrite and hydrogen evolution leads to the unstable and poor cycling life in ZIB systems, thus impeding the development of ZIBs. Herein, a facile polymer coating approach is applied to establish an artificial solid–electrolyte interface to restrain the frenzied growth of zinc dendrites and hydrogen evolution. The –CO–N–CO– group in polyimide (PI) has strong interaction with Zn2+. Therefore, PI coating significantly improves the wettability between anode and electrolyte and realizes rapid Zn2+ transfer kinetics. As a result, the PI‐Zn symmetrical battery not only reaches a stable cycling performance more than 900 h at 1 mA cm−2, but also owns a smaller overpotential than bare Zn. When integrating the PI‐Zn anode with a CaV8O20 cathode, the PI‐Zn//CaV8O20 battery maintains a capacity of 306.5 mA h g−1 after 2000 cycles, which is much higher than that (198 mA h g−1) of a Zn//CaV8O20 battery. This work provides a simple, yet effective method to improve the electrochemical performance of ZIBs.