Electric double layer charging of activated carbon nanotube supercapacitors

A new supercapacitor developed in this research operates by storing charge in the electric double layer that forms on the inside and outside walls of activated carbon nanotubes. A large specific capacitance with average values of 103.4 Farads/gram was obtained by coupling the nanotubes electric double capacitance with the large surface area of activated nanotubes. The nanotube with its high conductivity provides a good electrical return path which is essential in charging and discharging the electric double layer in the nanotube. Experimental measurements have been conducted to determine the charge and discharge capacitance of the non-activated and activated nanotube carbon electrodes. A specific capacitance reference base was developed from capacitance measurements of activated carbon materials used in commercial supercapacitors. The frequency response of non-activated and activated supercapacitors has provided data on the impedance and power factor of the nanotube supercapacitor. An electrical model of both the nanotube and the nanotube supercapacitor electrode has been developed. The potential benefit of the new nanotube carbons in supercapacitors may be to reduce the physical size and increase energy density of present supercapacitors.