Supercapacitors: from the Leyden jar to electric busses

Supercapacitors are introduced and reviewed as devices with very high electric power capability suggested to support and supplement other devices for electrochemical energy storage and conversion with higher energy content but lower power. They are currently of significant importance on the device and local (end-user) level already providing resources to meet power surge demands. In larger mobile systems (vehicles) they help meeting this demand and also offer high power storage capabilities when braking. On an even higher level, they can provide support for maintaining power quality and help in peak shaving. A brief historic background and general information is followed by an overview of materials and their combination into already marketed devices and in possible systems under development.