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Electrochemical capacitances of carbon powder treated with dielectric barrier discharge

Powdery activated carbons were treated using dielectric barrier discharge. In comparison with low pressure plasma, dielectric barrier discharge operated at atmospheric pressure can dramatically reduce the processing time and does not need vacuum equipment. In this study, electrochemical properties of Electric Double Layer Capacitors (EDLCs) made of oxygen plasma-treated powdery activated carbons were examined through Cyclic Voltammetry (CV), cole-cole plots and X-ray Photoelectron Spectroscopy (XPS). It was found that the specific capacitance of EDLCs could be improved by using oxygen plasma-treated activated carbon powder. A comparison of EDLCs using carbon powder treated for 15 S versus untreated EDLCs shows a 20% increase in specific capacitance, which indicates that the plasma treatment for EDLC's carbon powder are suitable for high-energy applications. The enhancement of capacitance was mainly attributed to an increase in the BET surface area of the carbon powder and the creation of phenolic hydroxyl groups on the surface of the carbon. The phenolic hydroxyl groups caused oxidation-reduction reactions, because oxygen was included in the operation gas. In addition, the phenolic hydroxyl groups improved the penetration of the electrolyte solution.