New Battery Design Could Help Solar and Wind Power the Grid

April 30, 2013 by Jeff Shepard

Researchers from the U.S. Department of Energy's (DOE) SLAC National Accelerator Laboratory and Stanford University have designed a low-cost, long-life "flow" battery that could enable solar and wind energy to become major suppliers to the electrical grid. The research, led by Yi Cui, a Stanford associate professor and member of the Stanford Institute for Materials and Energy Sciences, is a product of the new Joint Center for Energy Storage Research (JCESR), a DOE Energy Innovation Hub. Led by Argonne National Laboratory, with SLAC as major partner, JCESR is one of five such Hubs created by the Department to accelerate energy research and was established last November.

“This important early result from JCESR points to the value of mobilizing top researchers in a concerted effort to tackle major energy challenges,” said Patricia M. Dehmer, Acting Director of DOE’s Office of Science, which supports JCESR. “It also shows the potential for significant progress in batteries and energy storage through transformative scientific research.”

While solar and wind make a substantial contribution to the nation’s energy supply, they also create significant power fluctuations, which can sometimes exceed the tolerances of the electrical grid. “Flow” batteries, such as developed by Cui’s group, can smooth those fluctuations. Their new flow battery uses a simplified, less-expensive design than other batteries, which may improve its scalability and cost-effectiveness. In laboratory tests, it also demonstrated excellent energy-storage performance through the equivalent of more than 5 ½ years of daily charge and discharge cycles.

The new battery design consists of a single liquid made of abundant and inexpensive chemicals like sulfur and lithium, and doesn't require a membrane at all. Traditional flow-batteries are much more complex and require two tanks of liquids separated by a membrane. In tests, the new battery withstood more than 2000 complete charge-discharge cycles with no degradation in quality. The new battery's energy density is about 100 Wh/kg, which is less than that of lithium-ion batteries but more than today's flow batteries.

Going forward, Cui's group plans to make a laboratory-scale system to optimize its energy storage process and identify potential engineering issues. It also plans to start discussions with potential hosts for a full-scale field-demonstration unit.