Omron Corp. and Mitsui & Co. Ltd. will form a joint venture together with Okamura Laboratory Inc., which developed a electric capacitor system named ECaSS (Energy Capacitor System), and Power Systems Co. Ltd., the producer of the capacitor. Under the agreement, Omron and Mitsui will invest about ¥2 billion (about $18 million) in Power Systems to form a joint venture company that will continue to use the same name.

Michio Okamura, president of Okamura Laboratory will be the chairman of the new company. An Omron executive will serve as president.

Double-layer capacitors are an electric storage system that does not employ chemical reactions like conventional rechargeable batteries. Instead, they use a double-layer structure at each capacitor electrode. When a voltage is applied, one layer of electrolyte molecules combine at the surface of the electrode. Molecules in the the second layer move in an electrolyte solution, appearing around each electrode.

The electrical double layer at each electrode works as an insulator only when the voltage is below the decomposing voltage at which electrolysis starts. The capacitor uses the insulator in place of dielectrics used in conventional capacitors. Since the capacitor depends on the electric phenomenon, it theoretically offers an unlimited charge/discharge cycle, no electrical loss, high-speed charge/discharge along with a simple, inexpensive structure of carbon and aluminum electrodes.

Capacitor technology is available in backup batteries, but the charge capacity, or energy density, is relatively small and applications have been limited, the companies claimed.

Okamura said his company developed improved capacitor materials and electric circuits for it ECaSS systems introduced in 1992. The capacitor's developer claims it could break the limit of conventional, electric double- layer capacitors to provide energy densities comparable to that of nickel-metal-hydride and lithium-ion batteries.

Power Systems has been producing ECaSS products with current energy densities of 6Wh/kg to 12 Wh/kg (watt hour per kilogram). Once the joint venture is formed over the next month, Power System said it would offer new products with an improved energy capacity of 40Wh/kg, roughly the same level as nickel-metal-hydride batteries. the partners expect to deliver their first product by March 2005; 60 Wh/kg products equivalent to lithium-ion batteries are planned the following year.

Power Systems plans to expand production capacity to 300,000 cells a month in three years by investing about ¥2.5 billion (about $23 million) in a production facility.

The partners will promote the capacitor for a wide range of applications requiring large capacity and quick charge and discharge, such as storage systems for conventional and new energy generation, hybrid electric vehicles and power sources for home appliances.

By: DocMemory
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