Energy

High-voltage saltwater battery fails to fire

High-voltage saltwater battery...
Study co-senior author Dr. Kang Xu with the saltwater battery
Study co-senior author Dr. Kang Xu with the saltwater battery
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Study co-senior author Dr. Kang Xu with the saltwater battery
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Study co-senior author Dr. Kang Xu with the saltwater battery
Key to the advance in battery technology is the right mix of salt and water
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Key to the advance in battery technology is the right mix of salt and water

Back in 2015, a team of scientists made a battery breakthrough by using salty water as an electrolyte to offer a potentially safer and greener alternative to commercial lithium-ion batteries, but its voltage left something to be desired. The same team has now powered up its design to a point where it could be used in household appliances, without the risk of fire and explosion that can accompany conventional alternatives.

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

Key to the team's design, and many of today's batteries for that matter, is a protective layer called a solid-electrolyte interphase. This forms around the battery's anode when the energy-carrying electrolytes are broken down during the first charge, guarding it from chemical reactions that can cause fire, smoke and explosions and allowing it to operate at higher voltages.

It had been thought that this interphase was unable to form in aqueous batteries with water-based electrolytes, but in 2015 scientists from the University of Maryland and the US Army Research Laboratory did just that hitting just the right mix of salt and water. A high concentration of salt compared to water, six-to-one to be exact, allowed the interphase to form and boost the battery's maximum voltage from 1.23 V to 3 V.

Now the same researchers have raised the bar even further, by developing a new gel polymer electrolyte that coats the anode and better repels water from its surface, allowing it to hit a maximum voltage of 4 V.

"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.

While the work so far is promising, the team says further research is needed to explore how well the technology can be scaled up. It notes several aspects of the design that could be improved upon, including reducing material expenses and increasing the number of full-performance cycles it can complete.

"Right now, we are talking about 50–100 cycles, but to compare with organic electrolyte batteries, we want to get to 500 or more," Wang says.

If all goes to plan, the team estimates the technology could be ready for commercialization in around five years. The research is published in the journal Joule.

Source: US Army Research Laboratory

11 comments
JoelTaylor
Higher voltage is nice, but what's it's energy density?
Kpar
I have been told that use of salt in water as an electrolyte (in plating operations) has a distinct risk of the release of chlorine gas. What is the answer to that in this application?
CoachFerg
For more than 25 years I have read about the next big battery breakthrough. It always ends with an estimation of the arrival of this new battery technology to the clamoring public. Yet, the result never holds up to the promise.
I realize that there are hurdles to trying to improve energy density. I also realize, that reality often steps in to foil the most enthusiastic developer of new technology. But I do grow tired of predictions based on the very thinnest empirical evidence. I would rather they said that they have many things to overcome before production can begin. If they can deliver in five years, then that's great. However, if not, then they look like overly optimistic fools who cannot deliver what they promise.
Fretting Freddy the Ferret pressing the Fret
Cheap, scalable technology that delivers high performance is the key here. Fail to deliver on any of the above mentioned and it will not make it to the mass consumer market. Of course, that is a simplified picture.
Battery technology has many aspects to it, some of which were already mentioned. Consider the number of charge/discharge cycles before it degrades, toxicity of materials used, chemical stability, energy density, power density, and the list goes on.
noteugene
And yet another battery breakthrough. Yeah right.
Jim Parker
I don't know if Nick wrote the headline, but "fails to fire" sounds like "fails" to me. This looks like promising research, with a headline that failed to be clever.
JimFox
inside 5 years I am optimistic that a different technology will render this obsolete; the Toshiba battery has been used in EV's since 2007. "We will continue to improve the battery's performance and aim to put the next-generation SCiBTM into practical application in fiscal year 2019."
http://newatlas.com/toshiba-scib-battery-triple-range/51667/
Towerman
i'll never put a salt battery into my device, this idea was doomed from the start.
Towerman
@CoachFerg There are many breakthroughs, most choked by big oil, not because it is not possible.
Towerman
@JimFox
Indeed.