Pour to Recharge Your Electric Vehicle

Purdue University scientists have created a liquid-based battery that could one day be recharged at a gas station pump in just minutes

Dr. John Cushman with the flow battery (Purdue University)

Imagine pulling up to a gas station, popping open your tank, and pulling out the nozzle of the fuel dispenser. But instead of gas, out comes a mixture of water and alcohol. Instead of filling your fuel tank, the mixture recharges the battery of your electric car – instantly.

This is the dream of John Cushman, a Purdue University scientist who has developed an “instantly rechargeable” battery for electric cars. Cushman’s method uses water, ethanol (the same type of alcohol you’d find in alcoholic beverages), salt and dissolved metals. It would allow electric car owners to recharge their cars quickly and easily, using existing gas stations converted into battery recharging stations.

“We were trying to find an environmentally sound and economical way to power mobile vehicles like cars and trucks and golf cars, and do it in a way that you wouldn’t have to sit there and plug in your car for X number of hours,” Cushman says.

The battery is an example of a "flow battery," which uses two chemical compounds dissolved in liquids to form positively and negatively charged sides. The liquids are pumped into a battery cell that converts the chemical energy to electrical energy. Typically, flow batteries use membranes to separate the two liquids. But Cushman’s battery uses water and ethanol, and salt to force the water and ethanol to separate into two layers, with no membrane needed. This gives the battery an advantage over traditional flow batteries, Cushman says, since membranes are often the weak link.

“Membranes tend to break down, and when they break down the battery shorts out,” he says.

This method makes it possible to build a system with enough energy by volume to power a car.

“I don’t know if we can match what they have in lithium batteries, but we don’t have to,” Cushman says. "We actually believe we have enough power available to accelerate a light car quite quickly—but maybe not as fast as 0 to 60 in four seconds. Who really needs that type of acceleration? Most gas-powered cars don't come close."

While electric cars are growing in popularity, charging is a perennial issue. Tesla, whose Model S is the best-selling electric car in America, relies on a network of destination charging stations where drivers can plan to be for several hours or overnight, or supercharger stations, which charge cars in about 30 minutes. But, depending on where you’re driving, these stations can be few and far between. Enormous Midwestern states like Kansas and Missouri only have a handful, for example. This means a long-distance road trip in a Tesla takes careful planning. The fear of running out of charge far from a charging station is so common among electric car drivers it’s even got a name: ‘range anxiety.’

Cushman envisions gas stations converting to be battery fueling stations, perhaps one pump at a time as demand ramps up. Stations could use their existing infrastructure and transportation chain for the electrolyte fluid.

“The petroleum companies don’t want to see all their gas stations left by the wayside,” Cushman says. “We can pump our electrolytes through the existing pipelines. There’s nothing hazardous; it’s all biodegradable.”

The spent electrolytes could be dumped in storage tanks at gas stations and shipped to a refinery, ideally one powered by clean solar or wind enenergy. There, it could be reconstituted and shipped right back to gas stations.

“It’s a closed loop system,” Cushman says.

Cushman and his team, who have cofounded a company called Ifbattery LLC to commercialize the technology, are currently in talks with the military about using the battery technology to power quiet, stealthy vehicles with little heat signature to attract enemy attention. They’re also looking to build larger prototypes and to work with manufacturing partners to eventually bring the batteries to the civilian market. Cushman thinks there’s a “significant possibility” that the technology will be widespread on American roads in a decade, but hesitates to make predictions.

Though there are a variety of flow battery technologies out there, they’ve struggled to come to market and, when they do, they've had a hard time competing with the much more established lithium ion batteries. “[P]art of the problem with flow batteries is that most of the advances to date have been in the laboratory,” writes Peter Maloney in Utility Dive, a newsletter covering the utilities industry. “Li-ion batteries, on the other hand, have a long track record of in-field installations in everything from computers and smart phones to electric vehicles and megawatt scale grid-connected storage facilities.”

But advances such as Cushman’s may change the equation. Price will be a factor as well—previous flow batteries have tended to use relatively pricey metals such as vanadium. Cushman’s battery uses water, ethanol, salt and cheap aluminum or zinc.

“My responsibility was doing the chemistry,” Cushman says. “It's now just a small step to make a commercially viable product."

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