Effect of Carbon Pososity on the Electrochemical Properties of Carbon/Polyaniline Supercapacitor Electrodes

Supercapacitors have attracted great attention in power source applications, due to their high power density, elevated charge/discharge rate, good reversibility and long life. Activated carbons are the most frequently used electrode material, due to their high accessibility, non-toxicity, high chemical stability, good electrical conductivity, high surface area and low cost, but in practice the capacitance values are limited by the material microstructure. In this work we report on the synthesis and electrochemical characterization of carbon/polyaniline composites, synthesized by in-situ polymerization in acid media of aniline monomer on the surface of two activated carbons having different textural properties, and on the effect of the carbon porosity on the electrochemical properties of the electrodes. Results obtained indicate that the BET specific surface of the composites decreases sharply due to the collapse of the porous structure (mainly the micropores) of the carbon by the polyaniline chains. Regarding capacitance values, C-sp increases on increasing polyaniline loading in the composite, however high polymer concentration lead to a decrease on capacitance when high current were applied, probably due to diffusion restrictions of the electrolyte anions and cations to the carbon surface.