Advanced In Situ Electrochemical Induced Dual‐Mechanism Heterointerface toward High‐Energy Aqueous Zinc‐Ion Batteries

Abstract In situ electrochemical activation brings unexpected electrochemical performance improvements to electrode materials, while the mechanism behind is still needed to study deeply. Herein, an in situ electrochemically approach is developed for the activation of heterointerface MnO x /Co 3 O 4 by inducing Mn‐defect, wherein the Mn defects are formed through a charge process that converts the MnO x with poor electrochemical activities toward Zn 2+ into high electrochemically active cathode for aqueous zinc‐ion batteries (ZIBs). Guided by the coupling engineering strategy, the heterointerface cathode exhibits an intercalation/conversion dual‐mechanism without structural collapse during storage/release of Zn 2+ . The heterointerfaces between different phases can generate built‐in electric fields, reducing the energy barrier for ion migration and facilitating electron/ion diffusion. As a consequence, the dual‐mechanism MnO x /Co 3 O 4 shows an outstanding fast charging performance and maintains a capacity of 401.03 mAh g −1 at 0.1 A g −1 . More importantly, a ZIB based on MnO x /Co 3 O 4 delivered an energy density of 166.09 Wh kg −1 at an ultrahigh power density of 694.64 W kg −1 , which outperforms those of fast charging supercapacitors. This work provides insights for using defect chemistry to introduce novel properties in active materials for highly for high‐performance aqueous ZIBs.