Vertically-aligned graphene-carbon fiber hybrid electrodes and methods for making same

Abstract

Graphene electrodes-based supercapacitors are in demand due to superior electrochemical characteristics. However, commercial applications have been limited by inferior electrode cycle life. A method to fabricate highly efficient supercapacitor electrodes using pristine graphene sheets vertically-stacked and electrically connected to the carbon fibers which results in vertically-aligned graphene-carbon fiber nanostructure is disclosed. The vertically-aligned graphene-carbon fiber electrode prepared by electrophoretic deposition possesses a mesoporous three-dimensional architecture which enabled faster and efficient electrolyte-ion diffusion with a specific capacitance of 333.3 F g. The electrodes have electrochemical cycling stability of more than 100,000 cycles with 100% capacitance retention. Apart from the electrochemical double layer charge storage, the oxygen-containing surface moieties and α-Ni(OH)present on the graphene sheets enhance the charge storage by faradaic reactions. This enables the assembled device to provide a gravimetric energy density of 76 W h kgwith a 100% capacitance retention even after 1,000 bending cycles.