Highly dispersive nickel vanadium oxide nanoparticles anchored on nickel cobalt phosphate micron-sheets as cathodes for high-energy hybrid supercapacitor devices

Abstract

The effective strategies of customizing suitable orientation and rationalizing structures are significant for developing high-performance energy storage materials applied in supercapacitors, which are regarded as promising clean energy storage devices. To obtain highly efficient MOF (metal-organic framework)-derived phosphate electrode, it is necessary to combine it with highly conductive materials for a synergistical effect. So, in this work, the Ni-Co DH (double hydroxide) is used as sacrificial template to prepare MOF through a reverse strategy, which makes a foundation for shaping anisotropic orientation to impede structural stack. The Ni3V2O8 nanoparticles are dispersedly anchored on NiCo-P micron-sheet through a conversion from nanostructured MOF/Ni3V2O8. The evolution in structural size avoids agglomeration of Ni3V2O8 nanoparticles, which also leads to shaggy and intact NiCo-P micron-sheets, thereby improving fully contact with electrolyte. As a result, the obtained NiCo-P/Ni3V2O8 with abundant electroactive sites and valences displays extraordinary specific capacitance of 2520 F g−1 (1134 mA h g−1) at 1 A g−1 with capacitance retention of 89.05 % even when the current density increases to 10 A g−1. The NiCo-P/Ni3V2O8 and AC as cathode and anode, respectively, are assembled into a hybrid supercapacitor (HSC) device to fulfil requirement for high-performance supercapacitor devices. As-made NiCo-P/Ni3V2O8//AC HSC delivers preeminent specific energy density (SE) of 65 Wh Kg−1 at specific power density (SP) of 750 W Kg−1.