Electric double-layer capacitors based on charge storage at the interface between a high surface area activated carbon electrode and a propylene carbonate solution are widely used as maintenance-free power sources for IC memories and microcomputers. New applications for electric double-layer capacitors have been proposed in recent years. The popularity of these devices is derived from their high energy density compared with conventional capacitors and their long cycle life and high power density relative to batteries.
The performance of the capacitor depends not only on the materials used in the cells but also on the construction of the cells. The performance of power capacitors for large power sources as well as materials and construction of these capacitors are described.