Structure and operation of supercapacitors

The stracture of the supercapacitor cell, studied in this chapter, consists of two activated carbon electrodes and a separator rolled together and impregnated with an organic electrolyte. The electrodes are made up of an aluminum metalhc collector, coated on both sides with an active carbon powder material, which has a high surface area. The two electrodes are separated by a porous membrane (separator). 

In the case of a dielectric capacitor, the capacitance is given by equation [4.1], 

In order to increase the capacitance, we can increase the surface area and decrease the thickness. A snpereapacitor has an activated-caibon-based anode/cathode structure, which means its specific surface area is able to be considerably larger than conventional capacitors. This specific surface area may be as large as 2000 m /g. However, there is a part of this specific surface area which is not accessible, as we shall see later on Therefore, in practice, the specific surface area which plays a part in the component s capacitance is often far smaller, but nevertheless it is able to deliver very high capacitance valnes, ranging from 1 to 5000 F. At present, research is nnder way in order to achieve capacitances of 10000 F. 

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