Supercapacitors have attracted extensive attention in various storage devices due to their high power density, long life and friendly environment. Hence, improving the energy storage performance of electrode materials is of great significance to supercapacitor. Functional materials with specific nanostructures could display excellent electrochemical performance as energy storage materials, for they would provide rich electrochemically active sites, high specific surface area and enhanced electrolyte contact area. Consequently, hollow cage-like nickel cobalt layered hydroxides (NiCo-LDH) were prepared via nitrate etching of ZIF-67 nanocrystals, and investigated as electrode materials of supercapacitor. The morphology, structure and electrochemical properties of the obtained materials were investigated by means of X-ray diffraction, scanning electron microscope, transmission electron microscope, N2 adsorption/desorption and a series of electrochemical tests (including cyclic voltammetry, galvanostatic charge and discharge and AC impedance). The results showed that the NiCo-LDH samples assembled by nanosheets presented a porous structure with hollow cages and high specific area surfaces, which helped to increase the electroactive sites, enhance the contact between the electrolyte and the electrode material, and thus significantly improve the electrochemical performance of the materials. With the mass ratio of nickel and cobalt salts being 1:1, the specific capacitance of Ni1Co1-LDH was 801 F?g-1 at the current density of 0.5 A?g-1, and the specific capacitance of 582 F?g-1 could still be maintained at high current density of 10 A?g-1. Moreover, the specific capacitance retention of Ni1Co1-LDH was 100.2% after 2000 cycles at the current density of 15 A?g-1, displaying good electrochemical performance and great potential in supercapacitor applications.
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