Electrochemical Methods to Enhance the Capacitance in Activated Carbon/Polyaniline Composites

Abstract

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/AgCl͒. The prepared composite samples were characterized by cyclic voltammetry, galvanostatic charge-discharge tests, electrochemical impedance spectroscopy, and Fourier transform infrared ͑FTIR͒ 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.

Polyaniline-coated freestanding porous carbon nanofibers as efficient hybrid electrodes for supercapacitors

“…Assuming a contribution of 10 F g À1 from the NP-CNF substrate, the specific capacitance of PANI can be estimated as 570 F g À1 PANI . This value is comparable to several earlier studies [7,19]. However, the SEM image ( Fig.…”

“…Overall, these authors concluded that the potentiodynamic technique produces a more uniform PANI film due to periodic interruptions during polymerization between consecutive sweeps. This conclusion was also confirmed by Bleda-Matinez and co-workers [19] when electrodepositing PANI on high surface areaeactivated carbon. However, they preferred the potentiostatic method as it allowed the formation of a more porous PANI film that resulted in higher capacitance.…”

“…Based on the results from the potentiodynamic study, all subsequent depositions were carried out in solutions containing 0.5 M aniline and 1 M H 2 SO 4 to minimize degradation by-product formation. Previous reports [7,17,19] on the potentiostatic technique have utilized a constant potential in the range of 0.8e1.0 V. For the present study, potentiostatic electropolymerization was carried out at a potential of 0.8 V held constant for 20 s, accumulating a total charge of 2.6 C, which corresponds to 1.03 mg of PANI assuming a consumption of 2.4 electrons per aniline unit. The actual weight of deposited PANI was measured to be 1.0 mg, in good agreement with the calculated value.…”

Composite electrode composed of bimodal porous carbon and polypyrrole for electrochemical capacitors

“…The incorporation of active materials such as transition metal oxides [8][9][10] and conducting polymers [11][12][13][14][15] will increase the volumetric charge and discharge capacities of porous carbon. In this work, a composite electrode consisting of bimodal porous carbon and polypyrrole (PPy) was prepared by the electropolymerization of pyrrole within the macropores of bimodal porous carbon.…”

Relevance of porosity and surface chemistry of superactivated carbons in capacitors

“…An example for this possibility are carbon/conducting polymer composites, which can take the advantage from both, the double layer mechanism provided by porous carbon materials and the pseudo-capacitance contribution from conducting polymers. Our research group has prepared polyaniline (PANI)/ porous carbon composites by both chemical 16) and electrochemical polymerization methods 17) and those composites were characterized in terms of porosity and performance as electrochemical capacitors.…”