Three-dimensional hierarchical porous flower-like nickel-cobalt oxide/multi-walled carbon nanotubes nanocomposite for high-capacity supercapacitors

Three-dimensional (3D) hierarchical porous flower-like nickel-cobalt oxide/multi-walled carbon nanotubes (Ni-Co oxide/MWCNTs) nanocomposites were fabricated by a facile and template-free hydrothermal method as electrodes for high-capacity supercapacitors. The samples were characterized by energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption-desorption and thermal gravimetric analysis (TGA). The electrochemical performance was investigated by cyclic voltammetry (CV), galvanostatic charge-discharge, and cycle life. It was found that Ni-Co oxide/MWCNTs nanocomposites displayed a high specific capacitance (1703 F g (1) at a discharge current density of 1 A g (1)) and, additionally, an excellent cycling performance, retaining 97% of the maximum capacitance after 2000 cycles at 10 A g (1). Even at a high current density (20 A g (1)), the specific capacitance was still up to 1309 F g (1). This outstanding capacitive performance may be attributed to the ideal composition of the material and to its unique 3D hierarchical porous flower-like architecture. (C) 2014 Elsevier B.V. All rights reserved.