Electrical properties of electrical double layer capacitors with integrated carbon nanotube electrodes

Integrated carbon nanotube (CNT) electrodes for electric double layer capacitor (EDLC) were fabricated. CNTs were directly synthesized on the bulk Ni substrates by the plasma enhanced chemical vapor deposition of methane and hydrogen. No additional catalyst was necessary. The coin-type EDLC cells with directly grown CNT electrodes exhibited a rectangular cyclic voltammogram even at a scan rate of 1000 mV/s. Also, we could increase the capacitance of the CNT electrode from 38.7 to 207.3 F/g through surface treatment using ammonia plasma.