Water-based lithium-ion batteries without explosive risks now a reality

September 6, 2017
Water-in-salt electrolyte. Credit: Jhi Scott, ARL Photographer

Researchers at the University of Maryland and the U.S. Army Research Laboratory have developed for the first time a lithium-ion battery that uses a water-salt solution as its electrolyte and reaches the 4.0 volt mark desired for household electronics, such as laptop computers, without the fire and explosive risks associated with some commercially available non-aqueous lithium-ion batteries. Their work appears September 6 in Joule.

"In the past, if you wanted high energy, you would choose a non-aqueous lithium-ion , but you would have to compromise on safety. If you preferred safety, you could use an aqueous battery such as nickel/metal hydride, but you would have to settle for lower energy," says co-senior author Kang Xu, a lab fellow at the U.S. Army Research Laboratory specializing in electrochemistry and materials science. "Now, we are showing that you can simultaneously have access to both high energy and high safety."

The research follows a 2015 study in Science that produced a similar 3.0 volt battery with an but was stymied from achieving higher voltages by the so-called "cathodic challenge," in which one end of the battery, made from either graphite or lithium metal, is degraded by the aqueous electrolyte. To solve this problem and make the leap from three volts to four, the first author, University of Maryland assistant research scientist Chongyin Yang, designed a new gel polymer electrolyte coating that can be applied to the graphite or lithium anode.

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The video shows how an interphase precursor water in salt GPE demonstrates extremely low reactivity with lithium metal. Credit: Yang et al.

This hydrophobic coating expels water molecules from the vicinity of the electrode surface and then, upon charging for the first time, decomposes and forms a stable interphase—a thin mixture of breakdown products that separates the solid anode from the liquid electrolyte. This interphase, inspired by a layer generated within non-aqueous batteries, protects the anode from debilitating side reactions, allowing the battery to use desirable anode materials, such as graphite or lithium metal, and achieve better energy density and cycling ability.

"The key innovation here is making the right gel that can block water contact with the anode so that the water doesn't decompose and can also form the right interphase to support high battery performance," says co-senior author Chunsheng Wang, Professor of Chemical & Biomolecular Engineering at the University of Maryland's A. James Clark School of Engineering.

Water-in-salt gel electrolyte. Credit: Jhi Scott, ARL Photographer

The addition of the gel coating also boosts the safety advantages of the new battery when compared to standard non-aqueous lithium-ion batteries and boosts the energy density when compared to any other proposed aqueous lithium-ion batteries. All aqueous lithium-ion batteries benefit from the inflammability of water-based electrolytes as opposed to the highly flammable organic solvents used in their non-aqueous counterparts. Unique to this one, however, is that even when the interphase layer is damaged (if the battery casing were punctured, for instance), it reacts slowly with the lithium or lithiated graphite anode, preventing the smoking, fire, or explosion that could otherwise occur if a damaged battery brought the metal into direct contact with the electrolyte.

The video will load shortly.
This video shows how when punctured repeatedly with a nail, a four-volt aqueous lithium-ion battery initially maintains its voltage, and no fire, smoke, or explosion occurs. This contrasts with the instantaneous short-circuit and explosive risk of an analogous non-aqueous battery. Credit: Yang et al.

Though the power and energy density of the new battery are suitable for commercial applications currently served by more hazardous non-aqueous batteries, certain improvements would make it even more competitive. In particular, the researchers would like to increase the number of full-performance cycles that the battery can complete and to reduce material expenses where possible. "Right now, we are talking about 50-100 cycles, but to compare with organic batteries, we want to get to 500 or more," Wang says.

The researchers also note that the electrochemical manipulations behind the jump to four volts have importance within battery technology and beyond. "This is the first time that we are able to stabilize really reactive anodes like graphite and lithium in aqueous media," says Xu. "This opens a broad window into many different topics in electrochemistry, including sodium-ion batteries, lithium-sulfur batteries, multiple ion chemistries involving zinc and magnesium, or even electroplating and electrochemical synthesis; we just have not fully explored them yet."

Explore further: Scientists identify chemical causes of battery 'capacity fade'

More information: Joule, Yang et al.: "4.0 V Aqueous Li-ion Batteries" http://www.cell.com/joule/fulltext/S2542-4351(17)30034-X , DOI: 10.1016/j.joule.2017.08.009

L. Suo et al. "Water-in-salt" electrolyte enables high-voltage aqueous lithium-ion chemistries, Science (2015). DOI: 10.1126/science.aab1595

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16 comments

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24volts
4.2 / 5 (5) Sep 06, 2017
Remind us again ten years from now when it might actually be ready to sale on the open market so I can buy them. In the last couple of years I've seen probably 100 or more so called battery improvement articles on this site... I haven't seen one of them for sale yet. What I have seen is just more and more excuses for researchers to get more and more grants without actually producing anything of use.
Da Schneib
3.7 / 5 (3) Sep 06, 2017
Quite frankly I bought a plug-in beard trimmer a week ago and avoided all the battery powered ones. They're too fragile to use. I don't want to have to buy a new one every couple of years. It's wasteful and expensive. I'm throwing away the last ten years worth of trimmers with batteries-- all dead-- and won't look back for a long time if ever.

Now, my NiMH Makita drill, that's another story, and a much better one. But it takes a lot more batteries. Laptops, I'm on the fence. We'll see. I'll be avoiding Chinese laptop batteries, anyway. They really screwed that one up.
gregie2017
5 / 5 (1) Sep 07, 2017
Not putting a SALT battery in my electronics no thanks.
gregie2017
not rated yet Sep 07, 2017
Quite frankly I bought a plug-in beard trimmer a week ago and avoided all the battery powered ones. They're too fragile to use. I don't want to have to buy a new one every couple of years. It's wasteful and expensive. I'm throwing away the last ten years worth of trimmers with batteries-- all dead-- and won't look back for a long time if ever.

Now, my NiMH Makita drill, that's another story, and a much better one. But it takes a lot more batteries. Laptops, I'm on the fence. We'll see. I'll be avoiding Chinese laptop batteries, anyway. They really screwed that one up.


i once taken out the single cell in one of my trimmers and replaced it with a 1 cell old flat lipo, after a little mod, that trimmer sprung to life like it has never seen life before, trimmed my beard in a snap.
gregie2017
4 / 5 (2) Sep 07, 2017
Remind us again ten years from now when it might actually be ready to sale on the open market so I can buy them. In the last couple of years I've seen probably 100 or more so called battery improvement articles on this site... I haven't seen one of them for sale yet. What I have seen is just more and more excuses for researchers to get more and more grants without actually producing anything of use.

oil companies stalling the development?

100 ? more like several hundreds.
my question is how come NOT 1 not ONE makes it through, does big oil really dedicate their existance towards stopping all progress of all these breakthroughs ? ? ?
24volts
1 / 5 (1) Sep 07, 2017
I doubt it. Oil companies know what's coming down the road regardless of what they would like to have and most are getting into different types of alt energy and other stuff pretty quickly. They will always have oil business due to all the various chemicals made but will eventually lose most of the vehicle fuel business. They have to make up that money for the share holders somehow.
If I was to bet I would put my money on simple job security because it can take a ridiculous amount of time to get something though the patent office and you can be sure anything worthwhile will go through there. Then find some company willing to take on the design and pay royalties or some arrangement if the people that come up with it don't start a company themselves. It also takes a lot of money to set up a factory line big enough to make a business building batteries survive and be profitable whether it's a new business or an established one and that's just a beginning. I just wish it could go faster.
Eikka
3.7 / 5 (3) Sep 07, 2017
my question is how come NOT 1 not ONE makes it through


Because these inventions are overhyped and the press is overselling them for the sensationalism.

There's an universe of different chemical reactions that kinda sorta work, but ultimately don't work well enough to make a practical product. It's very rare that something just comes out of the left field and takes everyone by surprise, because the engineers have tried and discarded thousands and thousands of combinations over the years. These "new" batteries come out of ideas that have already been tried and failed, where someone picks it up and tries to make it work regardless - and that's a long uphill battle.

I mean, the first experiments with lithium batteries were in 1912. A working prototype was concieved in 1985, and the first commercial products in 1991. Then it took another 10 years before they became good enough for use in everyday items like cellphones.

Jitro
5 / 5 (2) Sep 07, 2017
I'd prefer the sodium cells over lithium ones, once this gel works so well. The sodium cells would be way cheaper.
antialias_physorg
3.7 / 5 (3) Sep 07, 2017
Remind us again ten years from now when it might actually be ready to sale on the open market so I can buy them..

Science reports on new findings - which essentially means "prototypes that barely hold together in the lab". And that's fine, because that's the whole point of science publications: Get the new knowledge out so that others can build on it.

There are many, many steps between the first scientific paper and a marketable product.
- Optimization
- Integration with available manufacturing techniques
- Reoptimization for lower tolerances in manufacturing than in the lab (which sometimes means you have to go back to the drawing board entirely)
- finding a market (a product doesn't just have to be better - it has to be *significantly* better to warrant the additional expenditure of a changeover)
- Market penetration

Each step takes at least several years.
Eikka
3.7 / 5 (3) Sep 07, 2017
Each step takes at least several years.


And by the time they're done, others will have evolved too, so the project is aiming at a moving target.

Ten years on, when the water battery is ready for market, conventional lithium batteries may have double the energy density and the buyers will compromize safety for lower price and higher capacity. That's exactly what happened with LiFePO4 based lithium batteries which promised to bring on a new era of safe lithium - and then they got stuck with lackluster energy density and fell behind the market, and the companies that produced them went bankcrupt and were sold off to the Chinese.

Eikka
4 / 5 (4) Sep 07, 2017
Science reports on new findings - which essentially means "prototypes that barely hold together in the lab". And that's fine, because that's the whole point of science publications


Although his comment wasn't about the report itself, but the article about the report which is a different thing. Articles on phys.org aren't scientific publications or reports, but plain popular journalism, which means they're clickbait and often deliberately misleading. People often confuse the two, like confusing tabloid journalism and yellow papers for news.

And science reporting itself is starting to game the system by turning towards clickbait, to attract more viewers and more circulation as people share the article, which correlates later with more citations because people remember your article and not the other guy's.

https://thewinnow...n-online
Eikka
3.4 / 5 (5) Sep 07, 2017
The problem with academic clickbait, compounded by journalistic clickbait - or sensationalism in general - is that it presents the state of science and the state of reality in a very distorted light.

For example, decades of smear campaigns from the conservative press paved the way for the Brexit vote in the UK; likewise decades of glowing non-critical reports of great advancements has lead to the popular belief and myth that the auto industry and "big oil" is in a conspiracy to suppress all alternative forms of propulsion all over the globe, which has lead to the public supporting tax policies and regulations that harm themselves economically and physically (see the diesel scandal).

Take documentaries like "who killed the electric car?" as an example of something the public takes for reality, concluding that it must be because of a conspiracy, just like the magic 100 MPG carburetor that popped up once per decade, that was supposedly suppressed by the oil industry.

Zzzzzzzz
not rated yet Sep 07, 2017
Quite frankly I bought a plug-in beard trimmer a week ago and avoided all the battery powered ones. They're too fragile to use. I don't want to have to buy a new one every couple of years. It's wasteful and expensive. I'm throwing away the last ten years worth of trimmers with batteries-- all dead-- and won't look back for a long time if ever.

Now, my NiMH Makita drill, that's another story, and a much better one. But it takes a lot more batteries. Laptops, I'm on the fence. We'll see. I'll be avoiding Chinese laptop batteries, anyway. They really screwed that one up.


I've got one of those rechargeable battery beard trimmers that has lasted for 20+ years......
Eikka
not rated yet Sep 12, 2017
I've got one of those rechargeable battery beard trimmers that has lasted for 20+ years......


I've got one that I left uncharged for some time, and it self-destructed. Turns out, even though the NiMH batteries inside were fine and are still fine as I manually recharged them, the circuit itself reset such that it would refuse to turn on anymore.

I solved the problem by soldering in an extra wire to the motor and a push button that connects it directly to the battery. The original circuitry works normally as long as the motor is started manually - which is curious. Probably planned obsolescence.

24volts
not rated yet Sep 12, 2017
"There are many, many steps between the first scientific paper and a marketable product.
- Optimization"

I call bs on this whole response.. You can optimize forever and never get a product on the market .. Nothing more than job security for lab techs

"- Integration with available manufacturing techniques
- Reoptimization for lower tolerances in manufacturing than in the lab (which sometimes means you have to go back to the drawing board entirely)"

If you can't build it in a factory then it's a waste of research time. The design should be worked out and capable before you even think about a factory for it. That doesn't take years

"- finding a market (a product doesn't just have to be better - it has to be *significantly* better to warrant the additional expenditure of a changeover)"

All it has to be is as good and be cheaper to buy!

"Each step takes at least several years".
Only for people that don't actually want to build a product but want research grants.
24volts
not rated yet Sep 12, 2017
They only thing that takes some time is actually getting a factory setup and if you actually have something worthwhile that people will want it doesn't take that long. Investors will supply money to build the factory if they think they will make a profit on it.

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