Chemical Vapor-Deposited Carbon Nanotubes as Electrode Material for Supercapacitor Applications

Abstract

ABSTRACTWe report the capacitance of entangled carbon nanotubes (CNTs) synthesized on flexible carbon fabric via water-assisted chemical vapor deposition. The CNTs were grown at atmospheric pressure with iron (Fe) as the catalyst, ethylene (C2H4) and 5%/95% H2/Ar as precursor gasses, and aluminum oxide as a buffer/barrier layer. The effect of the catalyst thickness (5 and 10 nm) on the specific capacitance was studied. The capacitance behavior of CNTs was evaluated by cyclic voltammetry measurements via a three-electrode system. The highest specific capacitance, approximately 56 F/g, was obtained for electrodes with 5nm Fe thickness. A nearly rectangular shaped cyclic voltammogram was exhibited for the CNTs grown on the carbon fabric. A specific power density of 0.012 KW/Kg and specific energy density 0.15 Wh/Kg were calculated from the galvanic charge/discharge (CD) curves. In addition, electrochemical impedance spectroscopy (EIS) revealed a characteristic supercapacitive behavior with a low equivalent series resistance of 7 Ωcm2.