Stanford University researchers have developed a new combination of materials that could see rechargeable batteries able to store large amounts of renewable power created through wind or solar sources.
The scientists say that with further development, the new type of battery, known as a flow battery, could deliver energy to the electric grid quickly, cost-effectively and at normal ambient temperatures.
While the technology itself is not brand new, it is only now that the kinds of liquids capable of delivering the required electrical current has started to become available in volume.
Theoretically, this liquid metal has at least 10 times the available energy per gram as other candidates for the negative-side fluid of a flow battery
In the past, the chemicals used have limited the technology in terms of either the amount of energy they could deliver, or required high temperatures or needed very toxic and/or expensive chemicals to operate.
However, Stanford's assistant professor of materials science and engineering, William Chueh, along with PhD students Antonio Baclig and Jason Rugolo, decided to try the materials sodium and potassium. They found that when mixed they form a liquid metal at room temperature, as the fluid for the electron donor - or negative - side of the battery.
"Theoretically, this liquid metal has at least 10 times the available energy per gram as other candidates for the negative-side fluid of a flow battery," the scientists said.
However, Baclig said they "still have a lot of work to do". He added: "This is a new type of flow battery that could affordably enable a much higher use of solar and wind power using Earth-abundant materials."
A new battery technology has so many different performance metrics to meet: cost, efficiency, size, lifetime, safety, and so on
In order to use the liquid metal negative end of the battery, the group found a suitable ceramic membrane made of potassium and aluminum oxide to keep the negative and positive materials separate while allowing current to flow.
The two advances together more than doubled the maximum voltage of conventional flow batteries, and the prototype remained stable for thousands of hours of operation. This higher voltage means the battery can store more energy for its size, which also brings down the cost of producing the battery.
"A new battery technology has so many different performance metrics to meet: cost, efficiency, size, lifetime, safety, and so on," added Baclig. "We think this sort of technology has the possibility, with more work, to meet them all, which is why we are excited about it."
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