New (Flow) Battery Design Could Help Solar and Wind Energy Power the Grid [View all]

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http://www6.slac.stanford.edu/news/2013-04-24-polysulfide-flowbattery.aspx

[font face=Serif][font size=5]New Battery Design Could Help Solar and Wind Energy Power the Grid[/font]

April 24, 2013

[font size=3]Menlo Park, Calif. — Researchers from the U.S. Department of Energy’s (DOE) SLAC National Accelerator Laboratory and Stanford University have designed a low-cost, long-life battery that could enable solar and wind energy to become major suppliers to the electrical grid.

"For solar and wind power to be used in a significant way, we need a battery made of economical materials that are easy to scale and still efficient," said Yi Cui, a Stanford associate professor of materials science and engineering and a member of the Stanford Institute for Materials and Energy Sciences, a SLAC/Stanford joint institute. "We believe our new battery may be the best yet designed to regulate the natural fluctuations of these alternative energies."

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In this video, Stanford graduate student Wesley Zhang demonstrates the new low-cost, long-lived flow battery he helped create. (Credit: SLAC National Accelerator Laboratory)

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Today's flow batteries pump two different liquids through an interaction chamber where dissolved molecules undergo chemical reactions that store or give up energy. The chamber contains a membrane that only allows ions not involved in reactions to pass between the liquids while keeping the active ions physically separated. This battery design has two major drawbacks: the high cost of liquids containing rare materials such as vanadium – especially in the huge quantities needed for grid storage – and the membrane, which is also very expensive and requires frequent maintenance.

The new Stanford/SLAC battery design uses only one stream of molecules and does not need a membrane at all. Its molecules mostly consist of the relatively inexpensive elements lithium and sulfur, which interact with a piece of lithium metal coated with a barrier that permits electrons to pass without degrading the metal. When discharging, the molecules, called lithium polysulfides, absorb lithium ions; when charging, they lose them back into the liquid. The entire molecular stream is dissolved in an organic solvent, which doesn't have the corrosion issues of water-based flow batteries.

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http://dx.doi.org/10.1039/C3EE00072A