Energy

MIT's improved all-liquid battery could make renewable energy more competitive

MIT's improved all-liquid batt...
By playing around with materials, researchers have reduced the operating temperature of an all-liquid battery to 450-500° C (842-932° F) (Image: Felice Frankel)
By playing around with materials, researchers have reduced the operating temperature of an all-liquid battery to 450-500° C (842-932° F) (Image: Felice Frankel)
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Led by Professor Donal Sadoway, the team at MIT has produced a new all-liquid battery with improved life and a lower cost than previous versions (Photo: M. Scott Brauer)
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Led by Professor Donal Sadoway, the team at MIT has produced a new all-liquid battery with improved life and a lower cost than previous versions (Photo: M. Scott Brauer)
By playing around with materials, researchers have reduced the operating temperature of an all-liquid battery to 450-500° C (842-932° F) (Image: Felice Frankel)
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By playing around with materials, researchers have reduced the operating temperature of an all-liquid battery to 450-500° C (842-932° F) (Image: Felice Frankel)
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Our ability to store energy has proven a big hurdle in the adoption of renewable energies. But now a team of researchers from MIT has developed a new all-liquid battery system that extends the life of such devices while also costing less to make, a development they say could make wind and solar energy more competitive with traditional sources of power.

Donald Sadoway, a professor of Materials Chemistry at MIT, has been exploring the potential of electrical-grid-scale liquid batteries for some time. These batteries comprise layers of molten material, the varying densities of which cause the layers to separate naturally, much like oil and water.

With magnesium used for one electrode, antimony for another and molten salt serving as the electrolyte, these systems needs to be heated to 700° C (1,292° F) to operate. But the researchers found that exchanging some of the materials, using one electrode made from lithium and another from a combination of lead and antimony, reduces the operating temperature to 450-500° C (842-932° F).

What truly surprised the researchers was the benefits of both the antimony and lead when mixed together to create the electrode. They had anticipated that the higher voltage of the antimony would be compromised by the lead, and the lead's lower melting point would be compromised by the addition of the antimony. Rather, they found that, while the combined melting point lay in between that of the individual materials, the hybrid metal retained the higher voltage of the antimony.

"We hoped (the characteristics of the two metals) would be nonlinear,” Sadoway says. “They proved to be (nonlinear), but beyond our imagination. There was no decline in the voltage. That was a stunner for us.”

Because the new version of the battery can operate at a lower temperature, the researchers say it will be easier to design and have a longer life, in addition to a lower overall cost. In testing, they found that after 10 years of daily charging and discharging, the battery should maintain about 85 percent of its initial efficiency. They claim this initial efficiency to be around 70 percent, a similar level to pumped-hydro systems which require both large water masses and hillsides to function.

"The fact that we don’t need a mountain, and we don’t need lots of water, could give us a decisive advantage,” says Sadoway.

He and his team will explore the effects of other metals on the battery system and are hopeful of further reducing its cost and operating temperature and improving overall performance.

The team's research was published in the journal Nature.

Source: MIT

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14 comments
David Clarke
Could Mercury be used, as it is liquid at room temperature? The question then is, which metal has the lowest melting point in the set-up?
The efficiency might be similar to pumped storage systems, but to have the same energy capacity, surely the liquid metal batteries would cost a huge amount more than hillsides and water.
Catweazle
Large quantities of liquid magnesium and liquid antimony eh?
What could possibly go wrong?
Kuberkoos
Interesting, what percentage of the stored energy will be used to keep the temp. at 500ºCover - say - 24 hours?
Paulinator
Please let there be a god...so that he can help us when molten salts, lead and antimony makes more environmental sense than water+gravity as an energy storage medium.
Jim Fiske
The round-trip AC-to-AC efficiency of large new pumped hydro plants is close to 85%, not 70% (and is that 70% DC-to-DC?). In other words, they have half the losses, or less, of the liquid battery approach. They don't run at high temperature or degrade over time. They last for 60+ years. They also can be built without hillsides (see gravitypower.net). Prof. Sadoway seems to produce a lot of hot air along with his hot battery.
Slowburn
Funny thing about digging a big hole you get a big pile of dirt. There are very few places where you cant find enough height difference to set up a pump storage hydroelectric system.
Synchro
I don't get all the hate going on here - the thing being presented is that they've been able to reduce the operating temperature of these batteries. So you're all complaining that 500 is too hot - where were you when they were operating at 700? Industrial processes manage temperatures like these all the time, but reducing it makes for lower energy consumption and safer operation, which all sounds good to me. Representing this as a bad thing seems backwards.
Practical changes like these can make a huge difference - when 'high temperature' (not room temperature) superconductors were discovered it meant that superconductors could be made using liquid nitrogen instead of liquid helium, that alone representing a 100-fold decrease in cost.
Stephen N Russell
& lower costs since competitive?
Kim Holder
The reaction itself produces some heat, so if you make the batteries large enough, you don't need to add heat any more once the reaction is going. Batteries have no moving parts. All you have to do is put the components in a good casing and it is pretty hard for anything to go wrong. They can be placed anywhere, put in quickly, and require much less up front investment than a water pumping system. I saw Sadoway's talk on TED and thought it was great. These batteries could make a big difference.