Meidensha Corporation and Sumitomo Electric Industries are developing a new electric double-layer capacitor (EDLC) which they plan to commercialise for pure electric and hybrid vehicles in 2015.
Meidensha's EDLC is a long life, compact bipolar structure with high number of charge-discharge cycles. The company has developed infrastructural devices such as momentary voltage drop compensators for stable electric supply and regenerative energy storage systems for electric railways.
The capacitor uses Sumitomo Electric's Aluminum-Celmet for the electrodes which offers lightness (the specific gravity of aluminum is about one-third that of nickel), greater electrical conductivity (or low electrical resistivity, less than half that of nickel) and corrosion resistance. These features make it suitable for use in lithium-ion and other rechargeable batteries operating at high charge/discharge voltages. Aluminum-Celmet can also be used for current collectors in capacitors.
In the development of the EDLC, Aluminum-Celmet is used for the current collector; carbon nanotubes for the active material, and non-combustible ionic liquid for the electrolyte. This has led to the recent achievement of a 3.4 times higher volumetric energy density, wider operating temperature range, and higher output density than the conventional EDLC that uses aluminum foil, activated carbon, and organic electrolytes.
Meidensha and Sumitomo Electric aim to increase the volumetric energy density by five times from the conventional level. The companies are planning to deliver sample products in 2013.
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