Carbon nanotube/RuO₂ nanocomposite electrodes for supercapacitors

Electrochemical characteristics of electrodes for supercapacitors built from RuO₂/multiwalled carbon nanotube (CNT) nanocomposites have been investigated. Capacitances have been estimated by cyclic voltammetry at different scan rates from 5-50 mV/s. Electrostatic charge storage as well as pseudofaradaic reactions of RuO₂ nanoparticles have been affected by the surface functionality of CNTs due to the increased hydrophilicity. Such hydrophilicity enables easy access of the solvated ions to the electrode/electrolyte interface, which increases faradaic reaction site number of RuO₂ nanoparticles. The specific capacitance of RuO₂/pristine CNT nanocomposites based on the combined mass was about 70 F/g (RuO₂: 13 wt % loading), and the specific capacitance based on the mass of RuO₂ was 500 F/g. However, the specific capacitance of RuO₂/hydrophilic CNT nanocomposites based on the combined mass was about 120 F/g (RuO₂: 13 wt % loading), and the specific capacitance based on the mass of RuO₂ was about 900 F/g.