Sizing Up Liquid Metal Battery Tech

Recently I got a glimpse at energy-related research in the works at MIT during an afternoon at the MIT Energy Initiative, an interdisciplinary program pursuing sustainable energy solutions. Among the mind-blowing projects is a liquid metal battery for grid-scale energy storage.

Energy storage will increase in importance as more renewable power sources like wind and solar come online and utilities work to set up smarter systems to handle them.

The problem with existing battery storage systems is the high pricetag, plus they tend to rely on rare earth elements--not great for the planet. The Sadoway Group, headed by materials chemistry professor Donald Sadoway, took a radical approach to battery development and came up with what might be a promising solution.

"Reactive metals such as lithium and the exotic metal oxides in lithium-ion batteries are harder to contain and to work with," Luis Ortiz, who is director of research for the group, told me. "We tried to switch that around and start earth-abundant first and see which systems would work to store electrical energy."

The scientists looked at aluminum smelters, which are giant current sinks, and came up with a small battery made from antimony and magnesium sandwiching an electrolyte. In case you're wondering why we don't use this kind of battery for small devices, it's because the layers need to be oriented a certain way. However, that makes it ideally suited for being stationed at the base of a wind turbine. Such a battery also has the advantage of enduring for a long time, Ortiz says, lowering the cost per kilowatt hour.

Scientific American's David Biello has a video of battery co-inventor David Bradwell, a PhD candidate at MIT, describing the technology in a blog post about it. Over the next year or so the group will be scaling up their battery from its small size to one that's a foot in diameter. It will have to be much larger than that to achieve grid-scale storage, but the team is optimistic.

"It's a design that's very robust, very forgiving," Ortiz says.

Photo: The inside of a liquid metal battery during testing. Credit: Patrick Gillooly/MIT News.