New chemistries found for liquid batteries

March 22, 2016 by David L. Chandler
An artist’s rendering of a calcium liquid battery. Credit: Christine Daniloff/MIT

Liquid metal batteries, invented by MIT professor Donald Sadoway and his students a decade ago, are a promising candidate for making renewable energy more practical. The batteries, which can store large amounts of energy and thus even out the ups and downs of power production and power use, are in the process of being commercialized by a Cambridge-based startup company, Ambri.

Now, Sadoway and his team have found yet another set of chemical constituents that could make the technology even more practical and affordable, and open up a whole family of potential variations that could make use of local resources.

The latest findings are reported in the journal Nature Communications, in a paper by Sadoway, who is the John F. Elliott Professor of Materials Chemistry, and postdoc Takanari Ouchi, along with Hojong Kim (now a professor at Penn State University) and PhD student Brian Spatocco at MIT. They show that calcium, an abundant and inexpensive element, can form the basis for both the negative electrode layer and the molten salt that forms the middle layer of the three-layer battery.

That was a highly unexpected finding, Sadoway says. Calcium has some properties that made it seem like an especially unlikely candidate to work in this kind of battery. For one thing, calcium easily dissolves in salt, and yet a crucial feature of the is that each of its three constituents forms a separate layer, based on the materials' different densities, much as different liqueurs separate in some novelty cocktails. It's essential that these layers not mix at their boundaries and maintain their distinct identities.

It was the seeming impossibility of making calcium work in a liquid battery that attracted Ouchi to the problem, he says. "It was the most difficult chemistry" to make work but had potential benefits due to calcium's low cost as well as its inherent high voltage as a negative electrode. "For me, I'm happiest with whatever is most difficult," he says—which, Sadoway points out, is a very typical attitude at MIT.

Another problem with calcium is its high melting point, which would have forced the liquid battery to operate at almost 900 degrees Celsius, "which is ridiculous," Sadoway says. But both of these problems were solvable.

First, the researchers tackled the temperature problem by alloying the calcium with another inexpensive metal, magnesium, which has a much lower melting point. The resulting mix provides a lower operating temperature—about 300 degrees less than that of pure calcium—while still keeping the high-voltage advantage of the calcium.

The other key innovation was in the formulation of the salt used in the battery's middle layer, called the electrolyte, that charge carriers, or ions, must cross as the battery is used. The migration of those ions is accompanied by an electric current flowing through wires that are connected to the upper and lower molten metal layers, the battery's electrodes.

The new salt formulation consists of a mix of lithium chloride and , and it turns out that the calcium-magnesium alloy does not dissolve well in this kind of salt, solving the other challenge to the use of calcium.

But solving that problem also led to a big surprise: Normally there is a single "itinerant ion" that passes through the electrolyte in a , for example, lithium in lithium-ion batteries or sodium in sodium-sulfur. But in this case, the researchers found that multiple ions in the molten-salt electrolyte contribute to the flow, boosting the battery's overall energy output. That was a totally serendipitous finding that could open up new avenues in , Sadoway says.

And there's another potential big bonus in this new battery chemistry, Sadoway says. "There's an irony here. If you're trying to find high-purity ore bodies, magnesium and calcium are often found together," he says. It takes great effort and energy to purify one or the other, removing the "contaminant" from the magnesium or vice versa. But since the material that will be needed for the electrode in these batteries is a mixture of the two, it may be possible to save on the initial materials costs by using "lower" grades of the two metals that already contain some of the other.

"There's a whole level of supply-chain optimization that people haven't thought about," he says.

Sadoway and Ouchi stress that these particular chemical combinations are just the tip of the iceberg, which could represent a starting point for new approaches to devising battery formulations. And since all these liquid batteries, including the original liquid battery materials from his lab and those under development at Ambri, would use similar containers, insulating systems, and electronic control systems, the actual internal chemistry of the batteries could continue to evolve over time. They could also adapt to fit local conditions and materials availability while still using mostly the same components.

"The lesson here is to explore different chemistries and be ready for changing market conditions," Sadoway says. What they have developed "is not a battery; it's a whole battery field. As time passes, people can explore more parts of the periodic table" to find ever-better formulations, he says.

Explore further: Liquid Battery Offers Promising Solar Energy Storage Technique

More information: Takanari Ouchi et al. Calcium-based multi-element chemistry for grid-scale electrochemical energy storage, Nature Communications (2016). DOI: 10.1038/NCOMMS10999

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22 comments

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gkam
1.8 / 5 (10) Mar 22, 2016
And no high-level radioactive waste!
MR166
4.3 / 5 (6) Mar 22, 2016
Here's hoping that this battery lives up to all expectations. Energy storage is the key to reliable, when needed and cost effective renewable power. A lot of backup fossil power plants could be shut down if they were not needed to even out the power and load variations on the grid.
WillieWard
2.6 / 5 (5) Mar 22, 2016
And no high-level radioactive waste!
If nuclear waste were so dangerous, as prophesied by gskam's decrepit mind, then all these people would be already dead:
https://fbcdn-sph...87_o.jpg
pntaylor
4.3 / 5 (3) Mar 23, 2016
And no high-level radioactive waste!


Radioactive materials are used for power generation not storage.
There are no batteries, in existence or being developed, which use radioactive material.
WillieWard
5 / 5 (2) Mar 23, 2016
Atomic battery is energy dense and safe as it uses Pu-238 (alpha particles) instead of Pu-239(neutrons).
https://en.wikipe..._battery
https://en.wikipe...enerator
http://www.gizmag...y/13076/
gkam
1 / 5 (6) Mar 23, 2016
Not a good sign, . . .

http://www.reuter...5N16U3XE

"Belgium's Tihange nuclear power plant evacuated-VTM"
Whydening Gyre
4.8 / 5 (4) Mar 23, 2016
And no high-level radioactive waste!


Radioactive materials are used for power generation not storage.
There are no batteries, in existence or being developed, which use radioactive material.

PN,
Technically... The energy stored in the radio active elements make it a "battery" (an energy storage medium). We just induce release with a (surprisingly efficient) artificial process.
Now, back to topic, please?
ogg_ogg
3.3 / 5 (3) Mar 23, 2016
At 550°C, this isn't ready for prime time, and I'd guess never will be. You know how hot that is?! But the concept does seem to be worthy of more work, as this article says, its a new paradigm. There's a lot of metal alloys out there...
Zzzzzzzz
4.3 / 5 (6) Mar 23, 2016
The 550C temp is low compared to other molten salt battery configurations. At generating plant output, or gigawatt scales, that temperature should not be a prohibitive issue.
MR166
5 / 5 (3) Mar 24, 2016
It would not be suitable for automotive use but there is no reason why 550C presents a problem in a stationary commercial application. Silica aerogel would make a perfect insulator for the system due to it's high efficiency and melting point.
Eikka
5 / 5 (1) Mar 27, 2016
but there is no reason why 550C presents a problem in a stationary commercial application.


Common steel and aluminium are not structurally stable at those temperatures, which requires more expensive materials to contain it. You have to remember these are large cells that weigh tons - a layer of aerogel would be crushed.

The 550C temp is low compared to other molten salt battery configurations.


Other molten salt batteries operate in the 300-400 C range, although some go up to 800.

The higher the temperature, the higher the heat loss, and the more is required of the insulation, again making it more expensive to construct.
Da Schneib
5 / 5 (4) Mar 27, 2016
Eikka disses another renewable.

Next. >yawn.<
Eikka
5 / 5 (3) Mar 28, 2016
Eikka disses another renewable.


What value is discussion if you are only allowed to mention the pros and never the cons?

That's not a discussion, that's just advertisement or propaganda: telling only half the truth.
gkam
1 / 5 (5) Mar 28, 2016
"That's not a discussion, that's just advertisement or propaganda: telling only half the truth."
------------------------------------

Correct: Why do you do it, Eikka?

All we get from you is why ideas will not work, although many are already working.
Captain Stumpy
4 / 5 (4) Mar 28, 2016
All we get from you is why ideas will not work, although many are already working
now this is hypocrisy it it's worst: especially considering you are the number one poster of derogatory statements about the safest electric sources on the planet

Now, i aint saying i agree with Eikka's comments all the time, but at least playing "devil's advocate" with information is far better than playing "hypocritical poster of fearmongering" without any reliable or accurate information like you, because that, liar-kam, is promoting propaganda, lies and false claims

and it is *definitely not* a representation of factual accurate evidence based data
(as a supposed engineer "consultant" who worked in the power industry should be making)

wanna talk about those safety statistics again, g?
what about this: https://www.youtu...yv9arXqU

https://www.youtu...xY-wOrI8

https://www.youtu...rcdMiIGs

https://www.youtu...Zm8XO7Zc
Uncle Ira
3.7 / 5 (6) Mar 28, 2016
Now, i aint saying i agree with Eikka's comments all the time, but at least playing "devil's advocate" with information is far better than playing "hypocritical poster of fearmongering" without any reliable or accurate information like you, because that, liar-kam, is promoting propaganda, lies and false claims


Cher you nailed that one. I don't always agree with Eikka-Skippy all the time either, but that is mostal political stuffs, but he usually always brings good science into the discussion as opposed to slogans and blahs lifted from blogs.

He thinks like a "real" engineer, he thinks about practical stuffs in the "real" world instead of dreamer visions from "someone not in the business". Some peoples sound like "real" engineers. Some some peoples just sound like pretend "real" engineers. (Like a bad soap opera script, eh?)
gkam
1 / 5 (5) Mar 28, 2016
Call it what you want: Lots of folk paid me very well for decades to hear me speak, even as a "pretend" engineer.

I suspect your wife tells you to go play with your radio.
Captain Stumpy
4.2 / 5 (5) Mar 28, 2016
Lots of folk paid me very well for decades to hear me speak, even as a "pretend" engineer
@liar-kam
and as i stated before, this does not make you correct when facing factual evidence that proves you wrong about a topic (that argument is called "argument from authority" and when you're wrong, you are simply wrong, regardless of your credentials or supposed career)

Also, as noted before, this doesn't mean you're a "Senior engineer" nor anything else other than someone who gave speeches
PERIOD
(see CA state law about that too)

the point is not and never has been "that" you did anything (no once really cares, plus Rule 37)
it has always been that you can't actually prove most of your comments with evidence
Uncle Ira
4 / 5 (8) Mar 28, 2016
Call it what you want: Lots of folk paid me very well for decades to hear me speak, even as a "pretend" engineer.
Only in your mind Cher, only in your mind. Otherwise you would have left an interweb trail. But the only trail you left was,,,,

https://disqus.com/by/gkam/ ,,,, hooyeei, that sure sounds like some good engineer speaking there.

I suspect your wife tells you to go play with your radio.
Well how about that thing, Cher you finally guessed one right. Yeah, she tell that to me a lot when I am in her way around the house.

But she is like the typical wife-woman too,,,

When I'm in the way: "Why you don't play radio Ira? You know you want to do that and I can not get this done with you underfoot."

And so then when I am keeping to my self and not being in the way it's: "Ira what it is going to take for you put that thing down and ???? or !!!!! or #### like I ask you four or three times already?"
Uncle Ira
4 / 5 (8) Mar 28, 2016
Also, as noted before, this doesn't mean you're a "Senior engineer" nor anything else other than someone who gave speeches
It is sort of like those "IT Analyst Computer Engineer" you get on the phone when you buy the new computer and it won't do right. The "real" engineers that used to be called customer service reps.

You ever have to talk to one of those peoples? I am not kidding, every time I have talked to one of them it was some person in India or Mongolia or somewhere.

When you get their accent and phrases together with my accents and phrases, especially when they are doing a whole lot of "know what you are about to say so I'll just interrupt to speed things along". hooyeei, you got the good show there.

Choot, even the Amazon-Shipping/Order-Skippys is using them now. Some couyon in India trying to tell about my box in the Texas warehouse,,,
gkam
1 / 5 (4) Mar 28, 2016
Thank you for demonstrating your extensive knowledge of liquid batteries.
Da Schneib
4 / 5 (4) Mar 29, 2016
@Ira, they ain't no better in the US, quite frankly. They does the user script where it's all your fault and they don't have to fix it.

I wouldn't trust any of the "support" peoples to fix jack diddly squat these days. They're there to keep you from complaining and they get mad and make up an excuse to hang up on you when you questions their BS.

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