Preparation and comparison of two electrodes for supercapacitors: Pani/CNT/Ni and Pani/Alizarin-treated nickel

Polyaniline in emeraldine form was synthesized in the presence of multiwalled carbon nanotubes (CNTs), and the electrochemical capacitance performance of thus formed composite as electrode material has been studied. The polyaniline/carbon nanotubes (Pani/CNT) composite is found to result in a higher specific capacitance than that of either composite constituent, attributable to the double-layer capacitance behavior of the nanotubes in the Pani/CNT system. However, once assembled into a two-electrode cell, lower than expected specific capacitance values from 1 to 20 F/g were obtained, and such reduction is most likely caused by the contact resistance between the Pani/CNT electrodes and the nickel (Ni) current collectors. To improve the situation, a chemical treatment was applied to the nickel foil, and the Pani solution is then deposited on the surface of the foil to form a coated structure (Pani/Ni). The thickness and weight of the Pani films can be controlled by adjusting the concentration of the Pani solution. The specific capacitance of the cell with electrodes made of the new Pani/Ni composite was found to reach as high as 35.5 F/g.