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U.S. engineers find way to build a better battery (Reuters)
* Posted on Wed Mar 11, 2009 7:15PM EDT
CHICAGO (Reuters) - U.S. engineers have found a way to make lithium
batteries that are smaller, lighter, longer lasting and capable of
recharging in seconds.
The researchers believe the quick-charging batteries could open up new
applications, including better batteries for electric cars.
And because they use older materials in a new way, the batteries could
be available for sale in two to three years, a team from Massachusetts
Institute of Technology reported on Wednesday in the journal Nature.
Current rechargeable lithium batteries can store large amounts of
energy, making them long-running. But they are stingy about releasing
their power, making them discharge energy slowly and require hours to
recharge.
Scientists traditionally have blamed slow-moving lithium ions -- which
carry charge across the battery -- for this sluggishness.
However, about five years ago, Gerbrand Ceder and a team at MIT
discovered that lithium ions in traditional lithium iron phosphate
battery material actually move quite quickly.
"It turned out there were other limitations," Ceder said in a telephone
interview.
Ceder and colleagues discovered that lithium ions travel through tunnels
accessed from the surface of the material. If a lithium ion at the
surface is directly in front of a tunnel entrance, it can quickly
deliver a charge. But if the ion is not at the entrance, it cannot
easily move there, making it less efficient at delivering a charge.
Ceder and colleagues remedied this by revamping the battery recipe. "We
changed the composition of the base material and we changed the way it
is made -- the heat treatment," Ceder said.
This created many smooth tunnels in the material that allow the ions to
slip in and out easily. "The trick was knowing what to change," he said.
Using their new processing technique, the team made a small battery that
could be fully charged in 10 to 20 seconds.
Ceder thinks the material could lead to smaller, lighter batteries
because less material is needed for the same result.
And because they simply tinkered with a material already commonly used
for batteries, it could be easily adapted for commercial use.
"If manufacturers decide they want to go down this road, they could do
this in a few years," Ceder said.
One glitch, Ceder said, would be handling the extra surge of power. "All
of the wiring has to get beefed up," he said.
(Editing by Maggie Fox and Cynthia Osterman)