If you didn’t buy one of the 96,000 electric vehicles (EVs) sold in the United States last year – out of 16.5 million new vehicle sales – it might be because you’re waiting for a lower price, longer driving range or quicker, more convenient recharging times. Consumer surveys suggest that more people would consider buying an EV if those three roadblocks weren’t standing in the way. A new type of “flow battery” under development by various technology companies holds the promise of removing all three. If the claims prove true, you might also be able to recharge an EV equipped with such a battery simply by “filling up” with a special electrically charged liquid, much as you would refill a gasoline or diesel vehicle.
That liquid is water. Or, at least water is its main ingredient.
Most EVs on the market today provide a range of about 100 miles on a charge and can take four to eight hours to recharge with a home outlet. Drivers of the Tesla Model S can brag about enjoying more than double that range and recharging quickly at the company’s Supercharger stations positioned around the country. But the company's $70,000-$93,000 base price is beyond what most people can afford for a new car.
The largest single-component cost in an EV is the battery. A flow battery could cost just one-fourth as much as a lithium-ion battery pack typically used in EVs while providing three times the range. That enticing projection comes from Grigorii Soloveichik, project leader on the water-based flow battery project at GE Global Research in Schenectady, N.Y.
Applying Soloviechik’s math to a Nissan leaf, a popular EV, you could see the car’s $29,000 price reduced by several thousand dollars and its range extended to about 250 miles on a full charge. (Nissan recently announced the replacement cost of the Leaf’s lithium-ion battery pack at $5,500.)
Flow batteries are already in use today in large, stationary installations used to store power generated from solar and wind sources. The challenge, according to Soloveichik, has been to develop a water-based flow battery that could be sized for use in an EV, which requires increasing its energy density dramatically. In partnership with the Lawrence Berkeley National Laboratory, Soloveichik and his team at GE believe they will be able to do that.
Described simply, a flow battery contains a two-sided cell or chamber. Inside, a positively charged liquid and a negatively charged liquid are pumped past opposite sides of a dividing membrane. The fluids release their charge through the membrane to power the vehicle’s electric motors. An EV would have separate tanks to hold each liquid.
This liquid electrolyte has been likened by some to saltwater, although not the kind from the ocean. It is water mixed with certain metal salts. The GE researchers, and others working on similar projects, don’t reveal their experimental chemistries. However, unlike gasoline and diesel fuels, the “saltwater” is non-flammable. It’s also described as environmentally benign and safer than other types of batteries.
An EV with a flow battery could be recharged in one of two ways. You could plug the car into an electrical outlet or high-speed charger, as you would any other EV. That would reverse the fluid back past the battery’s membrane, where it would pick up the incoming charge.
Both GE and others working on the technology say that a refilling station could be designed to replace the depleted fluid with a freshly charged batch. The old fluid could then be recharged for use by other customers. Such a filling station could even generate its own electricity on site, using wind turbines or solar panels, for example, and store it in a large-scale flow battery.
Close to Production?
A year after GE first announced its flow battery research project, Soloveichik offered a cautiously optimistic update. “We have built a prototype and performed some benchmark experiments,” he said in an e-mail. “The next step is further development the chemical catalyst that is key to the battery’s operation, so we can optimize composition and performance.”
Soloveichik projected that the research would bear fruit.
“We’re still at the early stages of development,” he said. “We think it will have future impact, but are still some years away before it will be commercially ready. The DOE (Department of Energy) wants a battery that can power a car for 240 miles. We think we can exceed that.”
Soloveichik was referring to the U.S. Department of Energy’s Advanced Research Projects Agency – Energy (ARPA-E), which is funding grants at national laboratories, including GE, to help develop longer-range, lower-cost batteries for EVs.
The auto industry is paying attention to Grigorii’s research. He confirmed that he’s had discussions with several major automakers about the technology but could not name them yet.
A 920-Horsepower Dreamcar
Could another lab be closer to the breakthrough needed to put a flow battery into a car? At the Geneva Motor Show this past spring, a Lichtenstein-based company, nanoFlowcell, displayed a tantalizing concept EV called the QUANT. The company says the strikingly styled car would have four electric motors, producing a collective 920 horsepower, to give blazing acceleration. Two onboard storage tanks for the flow battery would give the QUANT a 360-mile driving range, nanoFlowcell claimed.
So far, the company has released few technical details on its battery but does cite flow battery research being conducted by Germany’s Fraunhofer Institute for Chemical Technology (ICT). The ICT has successfully miniaturized such a battery and has, like GE, offered optimistic claims for use in future EVs.
Meanwhile, nanoFlowcell said it planned to build four drivable prototypes this year.
Should flow battery development achieve its goals of low cost and long range, the results would energize the market for EVs.