PVDC-Based Carbon Material by Chemical Activation and Its Application to Nonaqueous EDLC

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Abstract
An organic solvent-type electrolytic solution was employed for application on an electric double-layer capacitor (EDLC) made of a polyvinylidene chloride (PVDC) based carbon material. Although the PVDC-based carbon material showed an excellent capacitance over a 100 F/g in an aqueous solvent-type electrolytic solution, it showed that a very small capacitance value was obtained in an organic solvent-type electrolyte solution, which did not even exceed the value of 5 F/g. It also confirmed the most effective temperature to get a capacitance shifted was from 700 to 900°C. At this time, chemical activation with KOH was tried for improving of the performance of the capacitance on PVDC-based carbon. The double-layer capacitance affected by variations of the pore size distribution was explained on the basis of the conventional pore analysis by means of gas adsorption. It was confirmed that the chemical activation with KOH was quite effective for improving capacitance. After the activation with KOH, especially by the 400 wt % addition, the capacitance obtained a value as high as 55 F/g, which is equivalent to 220 F/g for a conventional three-compartment system with a reference electrode. It was confirmed that the impregnation of KOH is effective for widening the pore diameter and affect the improvement of the capacitance. The effect of the functional groups on the surface of PVDC-carbons is also mentioned. © 2004 The Electrochemical Society. All rights reserved.