High-performance symmetric supercapacitor based on flower-like zinc molybdate

Highlights: • Flower-like zinc molybdate has been prepared by using a facile hydrothermal method. • A symmetric supercapacitor was fabricated based on flower-like zinc molybdate and activated carbon. • ZnMoO₄ nanoflowers displayed a specific capacitance of 704.8 F g⁻¹ at 1.0 A g⁻¹ and kept 93.6% 10000 cycles at 8.0 A g⁻¹. • The symmetric supercapacitor showed an energy density of 22.45 Wh/kg at power density of 800.06 kW/kg. Flower-like zinc molybdate (ZnMoO₄) has been prepared by using a facile hydrothermal method. The ZnMoO₄ nanoflowers are characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning electron microscope techniques. The as-prepared material is evaluated as electrode materials for high-performance supercapacitors by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. In 2.0 M KOH electrolyte, the ZnMoO₄ nanoflowers display a high specific capacitance of 704.8 F g⁻¹ (three-electrode system). Moreover, the ZnMoO₄ nanoflowers can reach up to 568.3 F g⁻¹ at 5.0 A g⁻¹, and approximately 93.6% of the capacitance is retained after 10000 cycles at 8.0 A g⁻¹. A symmetric supercapacitor is fabricated based on ZnMoO₄ nanoflowers and activated carbon, and a specific capacitance of 63.13 F g⁻¹ is obtained at 1.0 A g⁻¹ with a high energy density of 22.45 Wh kg⁻¹ at power density of 800.06 kW kg⁻¹. The good electrochemical performance of ZnMoO₄ nanoflower not only is due to its unique nanostructures with large specific surface area, but also its excellent conductivity, which facilitates efficient charge transport and promotes electrolyte diffusion. These results indicate that the ZnMoO₄ nanoflower may be a promising electrode material for energy storage applications.