Selasa, 20 September 2011

supercapacitor


supercapacitor has a limited range of applications, advances in design might eventually expand the product’s utility. For example, researchers continue to develop and experiment with newer forms of dielectric materials, such as carbon nanotubes, polypyrrole, and barium titanate, which may improve capacitance and energy density. The concept of combining supercapacitors with alternative energy sources to replace car batteries has gained appeal within the current "green" movement, and several public transportation systems have created pilot trials for capacitor-run buses and trains. If these and other developments yield successful results, the electric double-layer capacitor may achieve greater functionality and gain a larger role within the energy industry.

Manufacturers evaluating various electrical sourcing options should examine the strengths and weaknesses unique to the double-layer format. A supercapacitor’s energy density ratio typically ranges between 0.5 and 10 Wh/kg (nominal voltage over weight), which is considerably higher than that of a standard capacitor. While this energy density is still relatively low compared to mainline batteries, such as the lithium-ion model, the supercapacitor’s power density far exceeds the level offered by its counterparts. Power density is contingent on a device’s rate of electrical charging and discharging, meaning that supercapacitors can both generate and distribute energy more quickly than most batteries.

In addition, supercapacitors stop charging when their capacity limit is reached, eliminating the need for detection units to prevent overcharging. Aside from its excellent power density, a supercapacitor also has high cycle efficiency and can undergo millions of charging sequences in its lifespan.

However, low energy density and low voltage tolerance limit the effectiveness of an individual double-layer capacitor as a storage unit, unless it is serially linked to a group of capacitors. Furthermore, the supercapacitor’s linear discharge method often prevents the full charge from being delivered, resulting in small but detrimental energy waste. The high rate of self-discharge (energy loss due to internal chemical reactions) is a similar concern. Supercapacitor controls and electronic switching equipment can also be complex, and typically necessitate workers with specialized operational skills.

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