Electric Double-layer Capacitor

An electric double-layer capacitor (EDLC), also known as supercapacitor, supercondenser, electrochemical double layer capacitor, or ultracapacitor, is an electrochemical capacitor with relatively high energy density. Their energy density is typically hundreds of times greater than conventional electrolytic capacitors.

A typical D-cell-sized conventional electrolytic capacitor may have capacitance of up to tens of millifarads. The same size EDLC might reach several farads, an improvement of two orders of magnitude. As of 2011 EDLCs had a maximum working voltage of a few volts (standard electrolytics can work at hundreds of volts) and capacities of up to 5 kF. The amount of energy stored per unit of mass is called specific energy, which is often measured in watt-hours per kilogram (W⋅h/kg) or megajoules per kilogram (MJ/kg). In 2010 the highest available EDLC specific energy was 30 W⋅h/kg (approximately 0.01 MJ/kg). Up to 85 W⋅h/kg has been achieved at room temperature in the lab, which is still lower than rapid-charging lithium-titanate batteries. As of 2012 commercially available EDLCs typically have mass-to-volume ratio between 0.33 and 3.89 kg/l.

Research is ongoing to improve performance. For example, an order of magnitude energy density improvement was achieved in the laboratory in mid-2011. Prices are dropping: a 3 kF capacitor that cost US$ 5,000 in 2000 cost US$ 50 in 2011.

EDLCs are used for energy storage rather than as general-purpose circuit components. They have a variety of commercial applications, notably in "energy smoothing" and momentary-load devices. They have applications as energy-storage and KERS devices used in vehicles, and for smaller applications like home solar energy systems where extremely fast charging is a valuable feature.

Read more about Electric Double-layer CapacitorConcept, History, Comparisons, Materials, Market

Famous quotes containing the word electric:

    The widest prairies have electric fences....
    Philip Larkin (1922–1986)