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MRI Reveals Mysteries inside Batteries for Gadgets and Electric Cars

The views expressed are those of the author and are not necessarily those of Scientific American.

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The ability to make batteries lighter, cheaper and longer lasting is crucial to the development and adoption of next-generation electronics—from mobile phones and tablets to electric cars. Advances in lithium ion batteries have helped slim down smart phones and put cars like the Nissan Leaf and Chevy Volt on the road. Yet lithium can also be volatile and has been accused of causing electrical fires in gadgets and even Volt test vehicles. Investigating the failure of a lithium ion or any other battery is difficult because any post-mortem requires opening, and thus destroying, the battery to see inside. A new technique could sidestep that problem.

A team of researchers from Cambridge University in England, New York University (NYU) and Stony Brook University in New York say they have developed a way to use magnetic resonance imaging (MRI) to inspect batteries noninvasively. The researchers focused on better understanding how and why lithium deposits build up on electrodes and elsewhere after charging.

Normally it’s best to avoid having any metal near an MRI, for fear of turning that metal into a projectile. (The MRI’s powerful magnetic field will strongly attract any nearby metallic objects.*) In addition, a metal’s conducting surfaces block radio frequency fields, so an MRI would not reveal much information about what’s deep inside a metallic object.

Not a problem, the researchers reported Sunday in Nature Materials. (Scientific American is part of Nature Publishing Group.) An MRI’s radio waves may not penetrate the metals in a battery, but they can scan and measure features on the battery’s surface. These measurements can be used to recreate two- or three-dimensional digital images of the battery, including any lithium deposits that may have gathered on the battery’s electrodes. Such deposits can contribute to overheating, battery failure and possibly even a fire or explosion, according to the researchers.

Researchers at Argonne National Laboratory in Illinois used nuclear magnetic resonance (NMR) spectroscopy in 2001 to first study the movement of lithium ions within a battery from the outside (pdf), but this work “does not offer the level of detail provided by our technique,” says Alexej Jerschow, an NYU chemistry professor who contributed to the research. “For example, we were able to obtain 3-D images of a battery before and after charging.”

MRI also proved more accurate than NMR, which doesn’t provide detailed information about what’s happening inside the battery. Scanning electron microscopy, another tool that has been used to study batteries, requires cutting a battery open. “Not only does one destroy the battery in the process, but also exposure to air alters the surfaces, so this technique does not really study the electrodes in their working condition,” Jerschow says. “MRI is nondestructive, so you can take a functioning battery and take an image of it, much like one can take an MRI of the human body.”

Jerschow and his colleagues are continuing to refine their approach to improve image resolution and reduce the amount of time it takes to obtain an image.

*Clarification (2/15/12): Neither the battery used during testing nor lithium itself is magnetic.

Image: MRI in the pristine (uncharged) state and after passing current. Courtesy of S. Chandrashekar, Nicole M. Trease, Hee Jung Chang, Lin-Shu Du, Clare P. Grey, Alexej Jerschow, and Nature Materials

Larry Greenemeier About the Author: Larry Greenemeier is the associate editor of technology for Scientific American, covering a variety of tech-related topics, including biotech, computers, military tech, nanotech and robots. Follow on Twitter @lggreenemeier.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. YetAnotherBob 12:38 pm 02/15/2012

    The writer doesn’t seem to be aware that an MRI is NMR. The name was changed for political reasons but Nuclear Magnetic Resonance Imaging is still the same thing.

    What these researchers did was to use a slightly different approach to see something that isn’t directly visible. There was some interesting computer analysis there. Please tell us more about it. This could open up whole new worlds in materials sciences.

    There is too much bowing to the merely political in this magazine. The current editor seems to do less of it than Rennie did. Improvement. Maybe that’s why I still subscribe, as do my children.

    I often wish that Scientific American would go back to the old days of having scientists write the articles, and not journalists who have talked to some scientists at some time.

    If I wanted the watered down presentation, I would subscribe to Discover or Popular Science. But, I want things a little closer to accurate and more detailed.

    Still, at least some of the Articles are written by the researchers, and there is more depth and accuracy than the ‘popular press’, while still being accessible to the layman.

    Oh for the days of ‘The Amature Scientist’ and ‘Mathematical Recreations’! I still treasure a copy from the 1960′s when Murry Gell-Mann explained Neutron Stars. That was a great issue!

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  2. 2. fyngyrz 1:00 pm 02/15/2012

    Nice to see an article on that old standby, batteries. But the future belongs to ultracapacitors for an amazingly long list of reasons: from lifespan, to charge and discharge rates, to environmental flexibility — there is presently a difference in capacity, but look at the rising curve for ultracaps and you’ll learn everything you’ll need to know: batteries are a doomed technology. Give it a few years, you’ll see.

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  3. 3. luhng 5:13 pm 02/16/2012

    so due to the nature tat everything is in the economy today yes this is the greatest idea. yet so everyone could still continue to make money there needs to be a balance found that everyone can enjoy. thus following all with the re distribution of funds. this in turn would not only create many different types of jobs for those that are seeking employment yet this would also bring in the unity that needs to happen.☺

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  4. 4. gavin3050 8:11 pm 02/16/2012

    {Normally it’s best to avoid having any metal near an MRI, for fear of turning that metal into a projectile. (The MRI’s powerful magnetic field will strongly attract any nearby metallic objects.*} This is incorrect. “Metal” and “metallic objects” are not dangerous around MRI, unless it is ferromagnetic, not paramagnetic such as aluminum or titanium. (Such as the pegs installed in my late wife’s neck to support her cervices damaged by her tumor, causing bone cancer.This error fooled all her doctors, for over a year, who prevented using MRI to discover more damage, or treat her before she died.)

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