Ultrahigh energy density asymmetric electrochemical capacitors based on flower-like ZnO/Co3O4nanobundle arrays and stereotaxically constricted graphene

Unique hierarchical flower-like ZnO/Co₃O₄nanobundle arrays were synthesizedviaa facile hydrothermal method and the electrode shows remarkable specific capacitance up to 1983 F g⁻¹at a current density of 2 A g⁻¹.