A facile preparation and electrochemical properties of nickel based compound-graphene sheet composites for supercapacitors

Composites of a nickel based compound incorporated with graphene sheets (NiBC-GS) are prepared by a simple flocculation, using hydrazine hydrate as flocculant and reductant, from a homogeneous intermixture of nickel dichloride and graphene oxide dispersed in N,N-dimethylformamide. Morphology, microstructure and thermal stability of the obtained products were characterized by field-emission scanning electron microscopy, X-ray diffraction and thermal gravimetric analysis. Furthermore, the electrochemical properties of NiBC-GS, as electrodematerials for supercapacitors, were studied by cyclic voltammetry and galvanostatic charge/discharge in 2 mol L-1 KOH solution. It was determined that for NiBC-GS annealed at 250 8C, a high specific capacitance of 2394 F g-1 was achieved at a current density of 1 A g-1, with 78% of the value (i.e., 1864 F g-1) retained after 5000 times of repeated galvanostatic charge/discharge cycling. The high specific capacitance and available charge/discharge stability indicate the synthesized NiBC-GS250 composite is a good candidate as a novel electrode material for supercapacitors.