Potassium can make electric vehicle batteries more efficient

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Potassium compounds are mainly used to produce fertilisers. Many potassium salts are of great importance in industrial applications, including nitrate, carbonate, chloride, bromide, cyanide and sulphate. Potassium carbonate is used, for example, in the manufacture of glass, and potassium hydroxide is used to make detergents and liquid soap. Potassium chloride is used in medicines and in brine. The impressive list has just been extended to include electric vehicle batteries. Researchers have figured out how to overcome the challenge known as “dendrites” to create a metal battery that performs almost as well as a lithium-ion battery, but relies instead on potassium, a cheaper battery that is more abundant and available in much larger quantities.

“By adding a small amount of potassium salt, lithium-metal batteries can become safer and even increase charging efficiency. Lithium-metal batteries are lighter and can store more energy than the most commonly used lithium-ion batteries, but their widespread use has been limited by safety concerns,” said Lauren Marbella, a researcher at Columbia University in New York.

“Unlike lithium-ion batteries, which typically have an electrode made of graphite, lithium metal batteries have an electrode made of lithium. Due to the nature of charging in lithium-metal batteries, this can lead to tiny deposits of lithium on the electrode surface called dendrites, which can cause short circuits, and short circuits can lead to explosions.”

“Basically, they cause the whole system to collapse, it’s a recipe for disaster,” Marbella said.

Marbella and his team have discovered that for lithium metal batteries, adding a small amount of potassium salt prevents dangerous deposits from forming on the electrode. “Whenever potassium was added to the battery, fewer of these microstructures were formed and we got a higher efficiency battery, although the team is still investigating exactly why,” said the researcher.

“The researchers found that adding potassium increased the charging efficiency of the batteries from 84 to 88 percent. Even a small increase in charging efficiency can have big consequences, especially in applications such as electric vehicles. Limited range is a major obstacle to the transition to electric vehicles in air and land. There are limits to how far a vehicle can travel before it needs to recharge its battery.

“The development of lithium-metal batteries will help eliminate some of the problems of limited range because they last longer,” Marbella said.

The next step could be to investigate exactly how the addition of potassium salt prevents the formation of deposits on the lithium electrode, so that this process can be further optimised.

“This research could lead to the discovery of next-generation battery chemistries that will improve energy density and safety. These could be lithium-sulphur or lithium-air batteries. This is critical for the electrification of the transport and aerospace sectors,” added Shahid Rasul of Northumbria University in the UK.

This is not the first time that the use of potassium in batteries has been discussed, with researchers at the Rensselaer Polytechnic Institute publishing a paper on the subject in the spring.

Source: ScienceDirect

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