Exfoliated graphite nanosheets/carbon nanotubes hybrid materials for superior performance supercapacitors

Nanostructured hybrid material of exfoliated graphite nanosheets and carbon nanotubes (GNSNT) served as supercapacitor electrode materials was presented. The nanostructured hybrid was prepared by a facile chemical reduction method. The hybrid material was characterized by X-ray diffraction technique, transmission electron microscopy, scanning electron microscopy, cyclic voltammetry, galvanostatic charge/discharge cycling, and four-point probe conductivity measurement to represent a well-defined nanostructure possessing a vast number of active sites and delivering the ingredients for a fast effective charge separation network. Our results clearly demonstrated that the hybrid possess a superior performance. A specific capacitance value 266 F/g was obtained for GNSNT hybrid electrode at a current density of 0.1 A/g, while it was only 185 F/g for exfoliated graphite nanosheets (GNS). At a higher current density of 2 A/g, the GNSNT electrode still keeps a specific capacitance of 220 F/g, which is more than double that of GNS. This synergistic effect of the nanostructured hybrid material offers an effective network for charge separation and therefore renders a significantly enhanced specific capacitance and rate capability.