The quest to develop better batteries continues in research facilities around the world. The goal is to develop batteries that store more energy and cost less money. But that’s not all. To be commercially successful, they must have a long service life and be environmentally safe. Scientists at Stanford University believe they are close to a battery breakthrough which could meet all of those objectives and give a big boost to the goal of powering the grid with renewable energy.
Flow batteries are considered prime candidates for grid scale energy storage. In a flow battery, two liquids — one having a positive electrical charge and another having a negative electrical charge — are separated by a membrane that allows electrons to pass between both fluids while keeping them physically separate. Flow batteries tend to be larger in size than comparable lithium ion batteries, which makes them problematic for use in vehicles, but space considerations are less important for batteries designed to store electricity for the grid.
Until now, flow batteries have had several limitations that kept them from commercial viability. They had low energy density, required temperatures as high as 400º F to operate, and/or used toxic substances that were dangerous to the environment and cost a lot of money. But a team at Stanford led by William Chueh, an assistant professor of materials science and engineering, says they have solved one third of the flow battery puzzle.
The team has developed a liquid metal solution made from sodium and potassium — both of which are non-toxic, abundant and inexpensive — that acts at the anode for a flow battery. The best part is, the liquid metal solution is effective at room temperature. Theoretically, this liquid metal has at least 10 times the available energy per gram as other candidates for the negatively charged fluid in a flow battery, according to Science Daily. In the lab, the new anode material is capable of storing twice as much energy as any other flow battery currently available. So far, the new battery has a useful life of several thousand hours.
“We still have a lot of work to do,” says Antonia Baclig, a Ph.D. candidate who is part of the research team, “but this is a new type of flow battery that could affordably enable much higher use of solar and wind power using Earth-abundant materials.” The research report was published on July 18 by the journal Joule.
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