A novel method for carbon modification with minute polyaniline deposition to enhance the capacitance of porous carbon electrodes

A novel method was developed for minute deposition of polyaniline onto microporous activated carbon fabric to enhance the capacitance of the carbon serving as electrodes for electrochemical capacitors. The deposition consisted of pre-adsorption of monomer into carbon micropores followed by electrochemical polymerization of the adsorbed monomer in a monomer-free H₂SO ₄ solution at 0.85 V vs. Ag/AgCl. In comparison with the conventional polymerization in a monomer solution, the developed deposition resulted in a polymer framework distributed over the vast surface in carbon micropores, thus leading to a lower resistance for ion binding with the polymer in H₂SO₄ during charge-discharge. The lower resistance gave rise to a higher specific capacitance for the deposited polymer. In the assembled two-electrode capacitors, the usage of polyaniline redox reactions to store charges was more prominent for polymer-carbon composite electrodes from the developed method because of the higher electrode open circuit potentials. The present work has demonstrated that a capacitance enhancement of >50% in comparison with bare carbon can be achieved with minute polyaniline deposition (<5 wt.%) using the developed method, while only 22% was reached using the conventional method.