Enhancing the capacitances of electric double layer capacitors based on carbon nanotube electrodes by carbon dioxide activation and acid oxidization

Abstract

Polarizable electrodes of electric double layer capacitors (EDLCs) were made from carbon nanotubes (CNTs). Effect of carbon dioxide activation together with acid oxidation for the electrodes on the characteristics and performances of electrodes and EDLCs was studied. Carbon dioxide activation changed the microstructure of the electrodes, increased the effective surface area of CNTs and optimized the distribution of apertures of the electrodes. Acid oxidization modified the surface characteristics of CNTs. Based on the polarizable electrodes treated by carbon dioxide activation and acid oxidization, the performances of EDLCs were greatly enhanced. The specific capacitance of the electrodes with organic electrolyte was increased from 21.8 F/g to 60.4 F/g.