Let other people try to reinvent the wheel, the mousetrap – or even themselves – in the current economy. A group of students and academics at Massachusetts Institute of Technology has radically redesigned the batteries for electric vehicles (EVs)—and their out-of-the-box ideas could, before long, make them as rich as oil barons.
The new, liquid batteries can be refueled in minutes, or swapped out like tires at a pit stop. And if that’s not enough, they are also lightweight and inexpensive. Although they are now in prototype stage, the introduction of smaller, lighter, easily rechargeable batteries could be a game-changer in the auto industry, making EVs fully competitive with conventional gas- or diesel-powered vehicles.
According to an article by David L. Chandler in the MITNews, the batteries rely on an innovative architecture called a semi-solid flow cell, in which the battery’s active components — the positive and negative electrodes, or cathodes and anodes — are particles suspended in a liquid electrolyte. These two different suspensions are pumped through systems separated by a filter, such as a thin porous membrane.
The work was carried out by Mihai Duduta ’10 and graduate student Bryan Ho, under the leadership of Professors of Materials Science W. Craig Carter and Yet-Ming Chiang. It is described in a paper published May 20 in the journal Advanced Energy Materials. The paper was co-authored by visiting research scientist Pimpa Limthongkul ’02, postdoctoral candidate Vanessa Wood ’10 and graduate student Victor Brunini ’08.
One important characteristic of the new design is that it separates the two functions of the battery — storing energy until it is needed, and discharging that energy when it needs to be used — into separate physical structures. (In conventional batteries, the storage and discharge both take place in the same structure.) Separating these functions means that batteries can be designed more efficiently, Chiang says.
In EVs, the new batteries would be refueled by pumping out the liquid slurry and pumping in a fresh, fully charged replacement; or by swapping out the tanks, while still preserving the option of simply recharging the existing material when time permits.
Flow batteries have existed for some time, but have used liquids with very low energy density (the amount of energy that can be stored in a given volume). Because of this, existing flow batteries take up much more space than fuel cells and they must be rapidly pumped. The new semi-solid flow batteries overcome this limitation, providing a tenfold improvement in energy density over present liquid flow-batteries, and lower-cost manufacturing than conventional lithium-ion batteries.
Because the material has such a high-energy density, it does not need to be pumped rapidly to deliver its power. “It kind of oozes,” Chiang remarked. In fact, he and his colleagues have found an appropriate name for the black goo: “We call it ‘Cambridge crude,’” Professor Carter said.
In addition to potential applications in vehicles, the new battery system could be scaled up to very large sizes at low cost. This would make it particularly well-suited for large-scale electricity storage for utilities, potentially making intermittent, unpredictable sources such as wind and solar energy practical for powering the electric grid.
Yury Gogotsi, a distinguished university professor at Drexel University in Philadelphia and director of Drexel’s Nanotechnology Institute, stated, “The demonstration of a semi-solid lithium-ion battery is a major breakthrough that shows that slurry-type active materials can be used for storing electrical energy.” This advance, he says, “has tremendous importance for the future of energy production and storage.”
Gogotsi cautioned that making a commercial version of such a battery will require research to find better cathode and anode materials and electrolytes, but said, “I don’t see fundamental problems that cannot be addressed.”
The new technology is being licensed to a company called 24M Technologies, headquartered in Watertown, Massachusetts, and founded in 2010 by Chiang and Carter along with entrepreneur Throop Wilder, who is the company’s president. The company already has raised more than $16 million in venture capital and federal research financing. The development of the technology was partly funded by grants from the U.S. Department of Defense’s Defense Advanced Research Projects Agency (DARPA) and Advanced Research Projects Agency – Energy (ARPA-E).
Continuing research on the technology is taking place partly at 24M, where some recent MIT (News - Alert) graduates who worked on the project are part of the team; at MIT in Cambridge, Mass., where professors Angela Belcher and Paula Hammond are co-investigators; and at Rutgers University in Newark, New Jersey, with Professor Glenn Amatucci. For more information, visit the MIT website.
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Cheryl Kaften is an accomplished communicator who has written for consumer and corporate audiences. She has worked extensively for MasterCard (News - Alert) Worldwide, Philip Morris USA (Altria), and KPMG, and has consulted for Estee Lauder and the Philadelphia Inquirer Newspapers. To read more of her articles, please visit her columnist page.Edited by
Carrie Schmelkin
