TECHNOLOgy REViEW


What are “supercapacitors” and what design benefits do they bring to key applications?


bernd heim at avnet abacus introduces a technology that is continuing to find new applications in energy storage and power backup


inTroducTion


Supercapacitors are devices, which on the energy storage spectrum, bridge the gap between rechargeable batteries and more traditional capacitor technology, such as electrolytic capacitors. The most common form of supercapacitor is the electric double-layer capacitor (EDLC), which stores electrical energy electrostatically through the separation of charge in a double layer interface between a conducting electrode and an electrolyte solution. Activated carbon is typically used as the electrode material because its large surface area aids volumetric efficiency thus increasing capacitance and enabling more compact devices. Supercapacitors also exhibit low ESR (equivalent series resistance), providing the rapid charge/discharge performance that distinguishes them from rechargeable batteries.


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EDLC devices also offer extremely long life, showing little deterioration after hundreds of thousands of charge cycles, compared to batteries that degrade in just a few years or after only a few hundred charge cycles. Supercapacitors were first marketed in the late 1970s, and the EDLC effect was observed some while before that, but it is only in the past decade or so, with the increasing importance of providing backup power for more and more electronic equipment and a greater consciousness about energy management, that supercapacitors have become widely available and used in a broad range of key applications, including: Intelligent metering, energy harvesting, renewable energy and a wide spectrum of industrial sectors.


continues p 6 > focus magazine - issue 16


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