High-performance chrysanthemum flower-like structure of Ni doped ZnO nanoflowers for pseudo-supercapacitors

In this study, the chrysanthemum-flower-like structure of Ni-doped ZnO nanoflowers pseudo-capacitance behaviour was synthesized by a conventional hydrothermal method. The X-ray diffraction (XRD) results showed that the prepared materials had formed ZnO and Ni-doped ZnO nanopowder in their hexagonal wurtzite structure. The morphologies of the Ni-doped ZnO have a chrysanthemum-flower-like structure, which was confirmed by SEM and HR-TEM. Galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electro-chemical impedance spectroscopy (EIS) techniques were used to investigate the pseudo-capacitance behaviour of Ni-doped ZnO. The Ni-doped ZnO nanoflower-modified electrode achieved a maximum specific capacitance value of 1090 F/g at 0.25 A/g, and 3 M KOH was used as the electrolyte. Eight thousand cycles of testing revealed that the Ni-doped ZnO nanoflowers electrode was very stable, far outperforming the stability of undoped ZnO nanoflowers modified electrodes. The fabricated Ni-doped ZnO nanoflower electrode has high capacitance retention and high columbic efficiencies of 101 % and 89 %, respectively. The prepared Ni-doped ZnO nano-flowers are a very effective electrode material and are considerably better suited for supercapacitor applications.