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Miscellaneous/Ultracapacitors 070330
 (March 2007) EEStor looks to “replace the electrochemical battery” with its  battery-ultracapacitor hybrid. Although traditional ultra caps can release a charge at high end rates, their weakness has been in energy storage.   EEStor’s system,  an Electrical Energy Storage Unit (EESU),  seems to overcome that problem with a specific architecture that appears to escape the traditional limitations of such  devices.  EEStor’s new power unit is a ceramic ultracapacitor with a barium-titanate dielectric , or insulator, that can achieve an exceptional high specific energy.  The company states that  its “system” has specific energy of approximately 280 Watt/hours per kilogram. (Lithium-ion has about 32 Watt-hours per kilogram.)  

One of the key challenges is to ensure that barium-titanate powders can be made on a production line with purity and stability.  “Purification gives you better production stability, gives you better permittivity, and gives you the high voltages you’re looking for,” says CEO and cofounder Richard Weir.  “We’ve now got the chemicals certified and purified to the point we’re looking for.”   (“Battery Breakthrough?” by Tyler Hamilton, Technology Review, 01/22/07)     

EEStor  states that is it using an automated production line and existing power electronics  to initially build a 15 kiloWatt energy storage system for a small electric car.  ZENN Motor of Toronto is receiving the new product.
 (July 2006) SuperCharged

Although the market for ultracapictors has grown from $38 million in 2002 to a projected $355 million in 2007, these energy storage alternatives to batteries have problems in limited energy storage and high cost. The present cost is about $9,500 kW/h. (Ed. note: This costly figure is much greater than the under $100 kWh for a Lead-acid battery.) Ultracaps store about 3-4 Wh/kg compared to 70 for Nickel-metal hydride and 130+ Wh/kg for Lithium-ion batteries. Researcher Michio Okamura claims to have developed an ultracap with 50 Wh/kg. (Ed. Note: the problem of commercialization is not yet apparent.)

Another drawback is the popular electrolyte for ultracaps, acetonitrile which burns and can release cyanide. The magic replacement electrolyte has not yet been found.

Despite limitations, Honda has been able to replace batteries with ultracaps in its FCX fuel cell/hybrid autos, and Toyota uses a Panasonic ultracap to power an electric-hydraulic pump in the mechanical braking system of the Prius. Honda uses a propylene carbonate electrolyte in the FCX assumedly to remove the safety problem of the  acetonitrile.
 (June 2006) Carbon Nanotubes boost ultracapacitor storage density

Researchers at MIT are pursuing  carbon nanotubes as replacements for activated carbon used in ultracapacitors to boost storage density efficiency and reduce internal resistance.

Performance data was not available. At the present time, the technology is only at the laboratory stage awaiting nanotube supply commercialization.

Electronic Products, April 2006, p.23