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Salt power: Watt's next in rechargeable batteries?

19 October 2012

As far as batteries are concerned, the gold standard is lithium ion, but lithium is expensive. Researchers believe sodium might be the next big thing.

Professor Reza Shahbazian-Yassar (standing) with students in his laboratory

At present, the gold standard in the industry is the lithium ion battery, which can be recharged hundreds of times and works really well. Its only problem is that it is made with lithium, which is not cheap. It could get even more expensive if more electric vehicles powered with lithium ion batteries hit the road and drive up demand.

“Some people think lithium will be the next oil,” says Reza Shahbazian-Yassar, an associate professor of mechanical engineering–engineering mechanics at Michigan Technological University.

Sodium may be a good alternative. “After lithium, it’s the most attractive element to be used in batteries,” Shahbazian-Yassar said. It’s also cheap and abundant.

It has just one drawback: sodium atoms are big, about 70 percent larger in size than lithium atoms, which can cause a battery’s electrodes to wear out faster. 

With a $417,000 US National Science Foundation grant, Shahbazian-Yassar is leading an effort to address these problems at Michigan Tech. “We have an opportunity to tackle some of the fundamental issues relating to charging and discharging of batteries right here,” he said. “We have a unique tool that lets us observe the inside of a battery.”

Using a transmission electron microscope, Shahbazian-Yassar and his team can peer inside and see how a battery is charging and discharging at the atomic level. “We will study these fundamental reactions and find out what materials and electrodes will do a better job hosting the sodium.”

Sodium ion batteries would not have to be as good as lithium ion batteries to be competitive, Shahbazian-Yassar notes. They would just need to be good enough to satisfy the consumer. And they could make electric cars more affordable, and thus more attractive. Moreover, they could reduce our dependence on fossil fuels, particularly if the batteries were charged using renewable energy sources.


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