Convergence to Efficiency: On The Prospects for HyperCapacitors


OK we'll admit it: "HyperCapacitor" is a term we just coined. But, if the innovations continue apace it will be appropriate. In recent months we covered ultra-capacitors for hybrid buses and trucks and for storing electricity produced by solar photovoltaic cells. Another post drew attention to a nanotech research breakthrough that might greatly increase the storage density of carbon-based ultracapacitors. That one generated hopeful comments about replacing Lithium or Nickel-based batteries with ultracapacitors in smaller vehicles. The capacitor breakthroughs are coming in waves, making it seem as if all we have to do is introduce one research team to another to make coping with climate change less daunting. Here's the latest. TOKYO (Nikkei)--"DuPont Teijin Advanced Papers (Japan) Ltd., a joint venture between DuPont of the U.S. and Teijin Ltd., has developed a capacitor that can be used as the auxiliary power source for large hybrid vehicles like trucks and buses"..."The new capacitor can store 50% more charge than devices developed to date and helps solve the problem of size, which is the biggest hurdle to the use of capacitors in large hybrid vehicles. With the new capacitor, a stack of only around 60 cells would be required for a hybrid bus, compared to the normal 90, in effect reducing the overall size by one-third". That's approximately a 50% improvement in ultracapacitance: an advantage hybrid truck designers could use to reduce size and weight of energy storage devices (leaves more room for passengers). Or, if utilized in tandem with the carbon nanotube breakthrough we wrote on earlier, the cumulative theoretical improvement would be an order of magnitude higher. We know that nanotube carbon forms are very expensive. But why not a mixture of regular granules and nanutubes to hit the right balance between cost of goods and storage density?

More on the DuPont-Teijin discovery: - "For the separator of the capacitor, the company used the high-function polymer aramid in place of cellulose paper. This boosted the heat resistance of the system by 120 degrees to 370 C. The higher temperature eliminates water, which can deteriorate the performance of the capacitor. Using the new separator, the company fabricated a typical cell capacitor measuring 20cm square. Tests showed that the device could hold around 50% more charge than conventional capacitors of this size...The company hopes to have a practical version ready in 2007".