Electrochemical capacitors fabricated with carbon nanotubes grown within the pores of anodized aluminum oxide templates

We have fabricated electrochemical capacitors using carbon nanotube (CNT) electrodes grown within the pores of anodized aluminum oxide (AAO) templates using a thermal–chemical vapor deposition. Anodization conditions were controlled to produce two different pore sizes; One with 33 nm in diameter and the other 200 nm, and their pore densities were determined to be 1.6 × 1010 and 4.0 × 108 cm−2, respectively. It is shown that the capacitance of the CNT electrodes grown within the AAO with pore sizes of 33 and 200 nm gives 3.81 and 0.53 F cm−3 at 100 mV s−1, respectively. It is further shown that superior high-rate capacitance is obtained from the CNT electrodes with the smaller pore sizes at high voltage scan rate. These improved electrochemical properties of the CNT electrodes in the smaller pore sizes may be attributed to a larger surface area of the CNTs.