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 mAh 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.