Electrochemical methods to enhance the capacitance in activated carbon/polyaniline composites

Activated carbon/polyaniline composites have been prepared using different electrochemical methods: single-step potentiostatic polymerization, multiple-step potentiostatic polymerization, and potentiodynamic polymerization with the anodic potential limits being fixed at either 0.75 or 1 V (vs Ag/AgCl). The prepared composite samples were characterized by cyclic voltammetry, galvanostatic charge-discharge tests, electrochemical impedance spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The synthesis conditions were found to strongly affect the electrochemical behavior of the samples. High capacitance was achieved by the potentiostatic polymerization methods. As a general trend, higher capacitance and lower resistance were observed in the composites than the sum of these parameters of the individual components. This benefit is attributed to the enhanced electron delocalization along the polymer chains in the composites resulting from the influence of the activated carbon, as evidenced by the FTIR. However, an influence of the polyaniline morphology induced by the porous carbon cannot be discarded. (C) 2008 The Electrochemical Society.