In situ synthesis of Ni_xCo_yO_z-C composites with rod-like Ni@C as support for potential application in supercapacitors

A novel Ni_xCo_yO_z-C composite has been synthesized by a one pot in situ hydrothermal method with rod-like Ni@C (Ni nanoparticles wrapped by C) as support. The structure and morphology of the composites are characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. As supercapacitor electrodes, the as-prepared composites present good electrochemical performance with a high specific capacitance (975 F g^-1 at the current density of 1.0 A g^-1) and good cycling stability (79% of capacitance still maintained after 1000 cycles). The electrochemical performance is mainly due to the active redox reaction provided by the polytype metal oxide and the faster electron transfer supplied by the conductive carbon support. These results indicate that Ni_xCo_yO_z-C composites have promising applications as supercapacitor electrode materials.