Potassium And Oxygen Make A Low-Cost Battery

Developing new battery chemistries that don’t rely on expensive and scarce raw materials may provide a new direction for battery development.

A new battery design using low cost potassium and oxygen from the air is showing promise, according to a recent news release from The Ohio State University. Although lithium ion batteries have become the standard for everything from cell phones, to electric vehicles (EVs), to power grid support for renewable energy, the high cost of the raw materials used to make the cells and the availability of those materials is becoming a concern. Researchers around the globe are looking for a way to make viable electrical energy storage devices out of cheaper and more plentiful materials.

Paul Gilmore and Vishnu-Baba Sundaresan are two researchers from The Ohio State University who are researching the possibilities of lower cost batteries using potassium and oxygen electrochemical reactions. (Image source: The Ohio State University)

First Developed in 2013

The OSU work centered on the construction of the battery’s cathode, which stores the energy produced by a chemical reaction in a metal-oxygen or metal-air battery. Potassium-oxygen batteries were invented in 2013 when a team of researchers from Ohio State, led by chemistry professor Yiying Wu, showed that, “the batteries could be more efficient than lithium-oxygen batteries while simultaneously storing about twice the energy as existing lithium-ion batteries.” But, as with so many new battery chemistries, potassium-oxygen batteries had problems with the number of times that they could be charged and discharged. The battery degraded with each charge, never lasting longer than five or 10 charging cycles—far away from the cycle-life needed to make the battery a cost-effective solution for storing electrical power.

It was determined that the degradation happened because oxygen “crept” into the battery’s anode—the negative electrode of the battery. The oxygen caused the anode to break down so that the battery could no longer supply a charge.

To counter the effect, Paul Gilmore, a doctoral candidate at OSU, began incorporating polymers into the cathode to see they could protect the anode from oxygen. The key, Gilmore said, was finding a way to bring oxygen into the battery—necessary for it to work—without allowing oxygen to seep into the anode.

Like Human Lungs

According to the OSU release, “This design works a bit like human lungs: 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. That third layer, made of the conducting polymer, allows potassium ions to travel throughout the cathode, but restricts molecular oxygen from getting to the anode. The design 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.”

Vishnu-Baba Sundaresan, professor of mechanical and aerospace engineering at OSU is quick to point out that this work, while promising, will still require more research before it is viable for practical battery development. Gilmore noted that, “Oxygen batteries have higher energy density, which means they can improve the range of electric vehicles and battery life of portable electronics, for example, though other challenges must be overcome before potassium-oxygen batteries are viable for these applications.”

Made From Economical Materials

Nonetheless, there is real interest in creating much lower cost batteries that use more readily available materials. Lithium-oxygen batteries—another possible energy storage solution can be expensive, and most designs use scarce resources, including cobalt. According to OSU, the lithium-ion batteries that power many electric cars cost around $100 per kilowatt hour at the materials level. The researchers estimated that this potassium-oxygen battery will cost about $44 per kilowatt hour.

 “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,” said Sundaresan. “Technology like this is key, because it is cheap, it doesn’t use any exotic materials, and it can be made anywhere and promote the local economy.”

Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.

 

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