The synthesis of hierarchical ZnCo2O4@MnO2 core-shell nanosheet arrays on Ni foam for high-performance all-solid-state asymmetric supercapacitors

Hierarchical ZnCo2O4@ MnO2 core-shell nanosheet arrays were successfully synthesized on Ni foam via a facile hydrothermal method followed by a calcination process. The fabricated ZnCo2O4@ MnO2 electrode exhibited a specific capacitance as high as 2170.00 F g-1 (2.60 F cm-2) at a current density of 3 mA cm-2 in a 1 M KOH solution. Furthermore, an all-solid-state asymmetric supercapacitor (ASC) device fabricated with the as-prepared ZnCo2O4@ MnO2 as the positive electrode and activated carbon (AC) as the negative electrode in the PVA/KOH gel electrolyte achieved a high energy density of 29.41 W h kg-1 at a power density of 628.42 W kg-1 and retained 95.3% of its initial capacitance after 3000 cycles at a high current density of 10 mA cm-2. With the smart design and remarkable electrochemical properties, the hierarchical ZnCo2O4@ MnO2 core-shell nanosheet arrays on Ni foam demonstrated great potential for further applications in the energy storage field.