Science Scope

At PolyPlus, batteries made of lithium and seawater

Posting in Energy

Is a lithium-water battery a glimmer of hope for the clean tech applications?

Batteries made of lithium metal are preferred over lithium ion technology, but because lithium metal reacts with water.

But it hasn't really made any sense to try to use it until now.

One California-based company called PolyPlus created a lithium-water battery that is making quite a splash. The underlying technology is a bit counter-intuitive, considering lithium reacts violently with water. To get around this though, PolyPlus found a way to protect the lithium metal with a membrane, so the ions could slip through and maintain a charge.

ARPA-E director Arun Mjumdar describes the new water battery technology as.. a fish in a glass tank.

For demonstration purposes at the ARPA-E conference, PolyPlus put the membrane-covered lithium pack into a glass of water and showed that it could produce enough energy to make an LED light glow.

The technology works like this: The battery reacts with the oxygen that is dissolved in water. And you know what? The water battery can produce 1,300 watt-hours per kilogram of electricity, according to Scientific American.

According to PolyPlus:

With the invention of the protected lithium electrode (PLE), PolyPlus has introduced a unique technology that makes lithium metal electrodes compatible with aqueous and aggressive non-aqueous electrodes, and enables the development of a new class of high energy density batteries.

Battery technology is dragging behind other clean technology developments. Better lithium batteries will give us energy security. Not mention, developing better lithium battery chemistry could help make electric vehicles more price competitive with oil guzzling cars.

For now, PolyPlus's batteries will be used to help underwater robots run. The lithium-seawater batteries will use the saltwater as the positive electrode. The technology is comparable to hydrocarbon fuel cells and in some respects, is much better than existing lithium ion battery technology.

Katie Fehrenbacher at Earth2Tech explains:

The water battery also doesn’t have to carry the positive electrode, or the water, inside it. PolyPlus’ water battery has an open system where the water of the surroundings connects with the lithium. That means the battery could be more simple and lower cost to produce.

The company is also producing a non-rechargeable and a rechargeable lithium-air battery. The more energy density you can cram into a battery, the more energy it can store... and the longer it will last. Energy density is key to a better lithium battery. And if such a battery could be used to power electric vehicles, the battery packs would last for longer distances.

It might be a long time before lithium-water batteries make their way into electric vehicles as lithium ion batteries have become the go-to technology. In a related note, we recently went to Tesla to find out about how lithium batteries are being used. What was surprising to me was how big the battery pack is. In case you missed it, you should watch our video on Inside Tesla's 1,000-pound battery pack.

via PolyPlus: Water Batteries Could Be Comin' Soon [Earth2Tech on Reuters]

Share this

Boonsri Dickinson

Contributing Editor

Contributing Editor Boonsri Dickinson is a freelance journalist based in San Francisco. She has written for Discover, The Huffington Post, Forbes, Nature Biotech, Technewsdaily.com, Techstartups.com and AOL. She's currently a reporter for Business Insider. She holds degrees from the University of Florida and the University of Colorado at Boulder. Follow her on Twitter. Disclosure