Posted: June 1, 2007

Nanotechnology tapped to boost hybrid car efficiency

(Nanowerk News) Nissan opened a facility to explore cutting-edge science like nanotechnology in its quest for environmentally friendly vehicles. The research at the new facility, the Nissan Advanced Technology Center, will include making more efficient batteries for hybrid cars, including using nanotechnology in the production of lithium-ion batteries.
Although much of the focus on the president's proposals for fuel alternatives for cars has been on hydrogen fuel cells and biofuels such as ethanol, Mr. Bush recently signed a $3.7 billion federal initiative supporting nanotechnology research across all fields.
"Nanotechnology has this tremendous possibility for creativity like we have never known before," Jim Gimzewki, a researcher at UCLA, told the NewsHour in July 2004. "Imagine you could arrange atoms anyway you wanted, all the way up to a thing, okay? And this thing could be anything."
Hybrid vehicles, such as Toyota's Prius and Honda's Civic Hybrid, already achieve high gas mileage and relatively low emissions using a combination of nickel-metal hydride (NiMH) batteries and a gas engine. The 2007 model Prius drives an EPA-estimated average of 55 miles per gallon and exceeds California's stringent emissions standards. NiMH batteries are safe and low-cost, but they suffer from poor performance at lower temperatures and have a relatively short lifespan of six years.
Nissan, which introduced a hybrid car last year using technology from Toyota, hopes to begin selling a hybrid using lithium-ion batteries with nano-materials by 2010. Conventional lithium-ion (Li-ion) batteries are much lighter and have a better self-discharge rate (energy lost when not in use) than NiMH batteries, but they are unstable and pose a risk in cars since they tend to get hot.
Nano materials could make the batteries safer and more efficient by increasing the surface area in the battery where energy is stored and released, thereby boosting charge and capacity -- similar to a how a sponge can hold more liquid than a wood block of the same size -- while keeping temperatures stable. Other car manufacturers, including Toyota, Honda and General Motors, are testing similar batteries in their hybrids.
Such research could have significant impact beyond the automotive industry -- it could increase the efficiency of virtually every product that runs on batteries. Cell phones, laptop computers and power tools could see longer battery life, increased power and faster recharge.
A team of engineers at the Massachusetts Institute of Technology is using nanotubes to improve ultracapacitors, an energy storage device similar to a battery. Ultracapacitors are relatively large and hold energy in an electric field, as opposed to batteries, which can be smaller and rely on a chemical reaction to produce power.
Energy storage in batteries and capacitors is directly proportional to the surface area of the electrodes, which is where energy is stored and discharged. The MIT researchers are increasing the storage capacity of ultracapacitors by using nanotubes, tiny filaments 30,000 times thinner than human hair.
"This configuration has the potential to maintain and even improve the high performance characteristics of ultracapacitors while providing energy storage densities comparable to batteries," Joel Schindall, one of the lead researchers, said in a press statement. "Nanotube-enhanced ultracapacitors would combine the long life and high power characteristics of a commercial ultracapacitor with the higher energy storage density normally available only from a chemical battery."
In January, A123 Systems, a supplier of lithium-ion batteries using nanotechnology, signed an agreement with General Motors to supply batteries for the car company's hybrid vehicles program. A123 Systems' battery technology is based on the invention of the MIT research team.
In a statement announcing the partnership, A123 Systems said that its batteries would have "higher energy density than traditional lithium-ion HEV cells while having one of the highest power to weight ratio of commercially available batteries."
All this is good news for car buyers concerned with rising gas prices and the environment. Most researchers and engineers believe that these new nano-enhanced batteries will be available within the next five years.
At Nissan, Senior Vice President Minoru Shinohara told the Associated Press that his company was developing a car capable of traveling 60 miles on about three quarts of gasoline.
"We have been preparing now for several years, and we are ready with several key kinds of advanced technology," Shinohara said.
Source: PBS Online Newshour (Tom LeGro)
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