Clemson University scientist Apparao Rao is working with a team of researchers to create a new generation of batteries that can provide critical security for the country’s energy security, such as electricity.
Emerging potassium-ion battery technology could be cheaper and safer than conventional lithium-ion batteries and could support lithium-ion batteries, despite their lower energy density, Rao, co-founder of Clemson Nanomaterials Institute said. Power density is not the most important thing for a network. Savings in labor, money and low maintenance costs are also important.
Many applications use lithium-ion batteries, from electric cars to cell phones to battery-powered devices. They have the highest energy density, but their flammable nature makes them potentially dangerous for large energy storage applications.
“The main problem with lithium-ion batteries is that they can ignite. The reason they ignite is because the liquid they contain – the electrolyte – is organic and flammable, so every time the battery [Li-ion] explode… it can ignite,” said Rao, R. A. Bowen Professor of Physics in the Department of Physics and Astronomy, College of Science.
During their research, Rao and his colleagues in China developed a complete “pocket” type of potassium-ion battery. When they cut the bag, not only did the potassium-ion cell not burn out, but it continued to work despite the damage, he said.
Cheaper than more
Another advantage of liquid potassium-ion batteries over their lithium-ion counterparts is that potassium is cheaper and more abundant than lithium. Potassium is the seventh most abundant element in the world, while lithium is only the 33rd most abundant element, Rao said. Not only is lithium rarer than potassium, but it does not perform well in its elemental form due to its high reactivity with other elements.
Although potassium is more desirable than lithium, it presents its own challenges for battery technology. Potassium has a lower energy density than lithium, and there is also a shortage of suitable materials to serve as cathodes in potassium-ion batteries. Cathodes are important for the development of potassium-ion batteries. Potassium ions are very large compared to lithium ions and cannot enter the cathode chamber easily. Prussian blue, a pigment invented in the early 1700s was once used to dye Prussian clothing, now for cathodes in many storage solutions. Rao and the Chinese scientists developed Prussian blue (PBA) analogues for their potassium-ion battery research, but found that the PBA molecules would break down when used.
“PBA has a similar structure with manganese atoms around it,” Rao said. “Potassium ions move in and out of the cell during the battery discharge and charging cycle. When PBA comes in contact with electrolytes, it dissolves [manganese atoms] and creates holes during battery operation. These differences cause the room to collapse and cause it to collapse when potassium enters the house.
The team overcame the problem by adding metal ions to the electrolyte and “nano-engineering” the PBA surface.
Improved stability
“We use a special electrolyte that stabilizes the PBA hole,” he explained. “At our destination, iron ions fill the voids left by the dissolved manganese and make the room stronger.” As a result, a potassium-ion battery with a nano-engineered surface that has been cycled 130,000 times (more than 500 days) has an incredible performance loss.
“The surprising thing is that the metal ions fill the space during the first 10 cycles and stabilize the cell so that the battery can last for thousands of cycles. In other words, the holes repair themselves within the first 10 minutes of battery life by filling the holes with iron [melted manganese at left]. Rao said.
Despite its improved durability, Rao said he doesn’t see potassium-ion batteries replacing their lithium-ion cousins, mainly due to lithium-ion batteries’ higher energy density. But potassium-ion batteries can outperform Li-ion batteries in some applications, Rao said, including power grid support. It is also interesting that graphite can be used as a negative electrode in potassium-ion batteries, and they can be produced using existing lithium-ion battery production lines, which reduces operating costs. production, he said.
Rao said the recent storms that swept through many states, leaving a trail of destruction in their wake, and similar negative effects could have on non-mobile Li-ion storage systems. “If you have lithium-based network security, it can burn. Therefore, potassium-ion batteries, such as those discussed in our study, are a good substitute,” he said.
The journal Nature Sustainability published the results in a paper titled “Surface-Substituted Prussian Blue Analogue Cathode for Sustainable Potassium-ion Battery.” In addition to Rao, researchers include Junmin Ge, Ling Fan, and Bingan Lu from the School of Physics and Electronics at Hunan University in Changsha, China; and Jiang Zhou of the School of Materials Science and Engineering, Central South University, also in Changsha.
