Supercapacitors represent one of the newest innovations in the field of electrical energy storage, and will find their place in many applications where energy storage is needed, or can help to the smoothing of strong and short-time power solicitations of a distribution network. Other system developments are going on, opening new fields in engineering sciences, based on new possibilities in the field of electrical energy storage. In comparison with classical capacitors, these new components allow a much more higher energy density, together with a high power density. Even if the energy density is not comparable with that one of electrochemical accumulators, the possible energy amount and storage time is compatible with many industrial requirements.