Preparation of Petal-like structure NiO@ZIF-67 nanocomposites for application to high-performance supercapacitors

Supercapacitors as green energy storage devices are widely utilized in vehicle manufacturing, rail transportation, power systems, and other fields. In this study, petal-like NiO was synthesized via a one-step hydrothermal method, followed by the preparation of NiO@ZIF-67 composite electrode material at room temperature. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) tests demonstrated that the NiO in NiO@ZIF-67 possesses a porous petal-like structure, with ZIF-67 particles uniformly growing on NiO sheets. The effect of ZIF-67 content on the electrochemical performance of NiO was investigated, and results showed that NiO@ZIF-67/1, prepared with a mass ratio of NiO to Co(NO₃)₂·6 H₂O of 1:1, exhibits the optimal electrochemical performance. The specific capacitance of NiO@ZIF-67/1 electrode material reached 188.44 F·g⁻¹ at 1 A/g. Furthermore, the symmetric supercapacitor assembled with NiO@ZIF-67 exhibited a maximum energy density of 41.76 Wh/kg at 1.4 kW/h, with a capacitance retention rate of 87.2% after 5000 cycles.