Free-standing NiCoSe2 nanostructure on Ni foam via electrodeposition as high-performance asymmetric supercapacitor electrode.

ABSTRACT

Designing a high-energy-density and power-density electrode for supercapacitors has become an increasingly important concept in the energy storage community. In this article, NiCoSe2 nanostructures were electrodeposited on nickel (Ni) foam and directly used as electrodes for supercapacitors. The effect on the morphology and electrochemical performance of NiCoSe2 prepared under different scan rates was measured through scanning electron microscopy and various electrochemical measurements. The resultant NiCoSe2 prepared with 5 mV s-1 exhibits a cross-linked porous nanostructure and a high specific capacitance of 2185 F g-1 at a current density of 1 A g-1. Taking advantage of these features, an ASC is constructed by using NiCoSe2 on Ni foam as the positive electrode and an active carbon electrode as the negative electrode with 3 M KOH as the electrolyte. The ASC displays a high-energy density of 41.8 Wh kg-1, an ultrahigh power output of 8 kW kg-1, as well as a long cycling life (91.4% capacity retention after 10 000 cycles). The excellent electrochemical performance makes the porous NiCoSe2 nanostructures a promising alternative in energy storage devices.