MIT technology aims to supercharge batteries

Scientist calls discovery a 'behavior modifier'

By Carolyn Y. Johnson
Globe Staff / March 11, 2009
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MIT scientists have developed a new battery technology that might one day allow people to charge their cellphones in 10 seconds, or top off an empty plug-in car battery in mere minutes -- reshaping the way such gadgets are integrated into our lives.

Scientists tweaked a common type of lithium ion battery by, in essence, creating the equivalent of on-ramps so that ions can easily enter an energy highway within the material. The advance allows the batteries to charge and discharge about 100 times faster than today's lithium ion batteries, according to Gerbrand Ceder, a materials science professor at the Massachusetts Institute of Technology. Ceder led the work, which will be published in tomorrow's issue of the journal Nature.

"If we made a cellphone battery that could charge in 30 seconds, I think people would change their lifestyles...You might settle for a smaller battery and you could almost stand by and sip your coffee and it's done," Ceder said. "That becomes a behavior modifier, and that's why I'm excited about it."

Ceder began the research to solve a mystery: batteries store energy, but charge and discharge relatively slowly, as positively-charged ions slowly migrate across the battery material to create a current. In earlier research, Ceder's laboratory found that lithium ions can actually move quickly through the battery material, suggesting that something else was slowing lithium ions' commute across the battery to a crawl.

Working with lithium iron phosphate, he found that those ions were stalled because they needed to find an entry point on the surface of the material to migrate from one side of the battery to the other. Ceder compared it to the challenge of navigating a city: unless a car can get on the highway, it may be stuck on the back roads.

To speed the ions along, he and graduate student Byoungwoo Kang developed a coating that gives the ions the ability to move quickly to entry points.

"We knew once it was on the entry way, it should go in very, very fast," Ceder said. "We built a beltway -- if you have to get to Rt. 9 in Wellesley but you are in Arlington, you really want to take Rt. 128, as opposed to city streets."

The technology has been licensed to a Belgian company, Umicore, and Ceder thinks it could be integrated into batteries within a few years, although there is no way to know when it would be commercially available. It wouldn't cost significantly more than a lithium ion battery today, Ceder said.

Ric Fulop, co-founder of Watertown battery company A123 Systems, said his company had an option to license the technology.

"From here to product takes a couple years, but it's very promising," Fulop said.

The new research doesn't address one of the biggest problems in batteries -- how to fit more energy storage into a smaller, lighter battery. But it is still a significant advance, according to Yi Cui, a professor of materials science at Stanford University, who was not involved in the study.

"Since energy storage devices were invented, everyone is looking at" the charge and discharge rate of batteries, Cui said. "Everyone would like to improve it... what Professor Ceder is showing right here is a big improvement."

Ceder envisions such a battery as having many possible applications. Batteries that could discharge quickly, creating a burst of energy, could help cars powered by electric batteries accelerate on the highway. They could lead to a new generation of gadgets that charge ultrafast. Fast energy storage could be used to quickly stabilize the electricity grid, absorbing or releasing power to the system to smooth out fluctuations in power as demand goes up and down.

Fast-charging batteries could also theoretically help quickly charge electric batteries for cars, although he says charging such a large battery quickly wouldn't be possible today because it would be limited by the amount of power available to households given today's electricity grid. There may be more applications, including ones that no one has yet thought of, because of the constraints of energy storage today.

Ying Wu, a senior analyst at technology consulting firm Lux Research, said that because the technology was based on an existing type of battery, it might be able to enter the marketplace faster than one made of a novel material.

Fast-charging "is one of the performance attributes required for vehicle applications right now -- all the batteries people are developing for hybrid or electric vehicles would typically require an overnight charge," Wu said.

A faster method of charging, she said, "will dramatically improve the flexibility of these batteries."

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