Ohio State University (OSU) researchers have built a more reliable and longer lasting potassium-oxygen battery.
The highlight of the new battery is its cathode, which stores the energy produced by a chemical reaction in a metal-oxygen or metal-air battery.
According to the researchers, this new development could make renewable energy sources like solar and wind a lot more viable for the power grid through cheaper and more efficient energy storage.
“If you want to go to an all-renewable option for the power grid, you need economical energy storage devices that can store excess power and give that power back out when you don’t have the source ready or working,” explains professor Vishnu-Baba Sundaresan.
Potassium-oxygen batteries have been on the horizon since 2013, yet very little has been done to bring them on par with lithium batteries.
Chemistry professor Yiying Wu and his team have now shown that the batteries can be made more efficient than lithium-oxygen batteries, while storing about twice the energy as existing lithium-ion batteries.
The OSU study wasn’t without its challenges: Potassium-oxygen batteries tend to degrade with each charge, never lasting longer than five or 10 charging cycles.
This degradation happens on account of oxygen creeping into the battery’s anode. The oxygen causes the anode to break down, making the battery incapable of supplying a charge.
To remedy this, Paul Gilmore – a doctoral candidate in Sundaresan’s lab – started incorporating polymers into the cathode to swell it.
The key here, says Gilmore, is finding a way to bring oxygen into the battery without allowing it to seep into the anode.
The newly designed battery works more or less like a human lung: Air comes in to the battery through a fibrous carbon layer, then meets a second layer that is slightly less porous and finally ends at a third layer, which is barely porous at all.
The third layer, made of the conducting polymer, allows potassium ions to travel throughout the cathode, but restricts molecular oxygen from getting to the anode.
This means that the battery can be charged at least 125 times – giving potassium-oxygen batteries more than 12 times the longevity they previously had with low-cost electrolytes.
Image and content: ShutterStock/Ohio State