Three Dimentional Graphene-CNTs Foam Architectures for Electrochemical Capacitors

Abstract

Electrochemical capacitors are promising alternative energy storage systems dueto their relatively fast rate of energy storage and delivery. We describe a simple andscalable method to grow three-dimensional (3D) graphene/multi-wall carbon nanotubes(MWNTs) hybrid nanostructure on industrially used foamed metal foils (nickel foam) viaa one-step ambient pressure chemical vapor deposition (APCVD). The as-growngraphene/MWNTs carbon nanostructure foam demonstrates a homogeneous and denselypacked hierarchical nanostructure and possesses a high surface area which can bepotentially used for the electrodes of energy storage devices such as supercapacitors andbattery. Symmetrical electrochemical double-layer capacitors (EDLCs) ofgraphene/MWNTs nanostructures shows a high specific capacitance of 286 F g-1 whichleads to an energy density of 39.72 Wh kg-1 and a superior power density of up to 154.67kW kg-1. Moreover, the capacitance retention of ~100% after 11000 charge-dischargecycles demonstrates the high stability of the material for electrodes of supercapacitor.These merits enable the innovative 3D hierarchical graphene/MWNTs foam to serve asEDLC electrodes, resulting in energy storage devices with high stability and powerdensity.