Disordered Structure and Reversible Phase Transformation from <scp>K‐Birnessite</scp> to <scp>Zn‐Buserite</scp> Enable High‐Performance Aqueous Zinc‐Ion Batteries

The layered δ-MnO2 (dMO) is an excellent cathode material for rechargeable aqueous zinc-ion batteries owing to its large interlayer distance (~0.7 nm), high capacity, and low cost; however, such cathodes suffer from structural degradation during the long-term cycling process, leading capacity fading. In this study, a Co-doped dMO composite with reduced graphene oxide (GC-dMO) developed using simple cost-effective hydrothermal method. degree of disorderness increases hetero-atom doping composites. It demonstrated that GC-dMO undergo transition K-birnessite Zn-buserite phase upon first discharge, which enhances intercalation Zn2+ ions, H2O molecules in structure. exhibits 302 mAh g−1 at current density 100 mA after cycles as compared (159 g−1). electrochemical performance Co-doping sheets gap disorderness, maintains stability, facilitates easy reverse de-intercalation ions molecules. Therefore, promising large-scale ZIBs.