TOKYO Four companies have agreed to form a joint venture company to promote an electric double-layer capacitor system. Also know as super, or ultra, capacitors, the next-generation electric charge capacitor could eventually replace nickel-metal-hydride and lithium-ion batteries in certain areas.
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.
EDL capacitors stores electricity without using chemical reactions like conventional rechargeable batteries. Instead, it uses a phenomenon called electric double layer back 1879 by German inventor Hermann Ludwig Ferdinand von Helmhotz. The electric double layer functions like dielectrics in conventional capacitors. Depending only on the electric phenomenon, it offers the advantages of theoretically unlimited charge/discharge cycle life, no electrical loss, high-speed charge/discharge and a simple, inexpensive structure of carbon and aluminum electrodes. EDL capacitors are widely used in bac-up power applications where small capacity up to about 100 farads are needed.
Okamura optimized the materials for the capacitor to improve performance, adding electric circuitry to each capacitor to precisely control the maximum charge voltage. The ECaSS technology therefore combines a capacitor and a peripheral circuit.
Capacitors are connected serially to provide a larger energy supply. Each capacitor has the electric circuit, or parallel monitor, which controls the maximum charged voltage of each capacitor at the same level. The structure allows many capacitors to be connected serially.
Okamura developed an ELD capacitor in 1992 using improved capacitor materials and adding an electric circuit to each capacitor. The capacitor was later named ECaSS. 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.