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refillable single flow battery


Another Way To Power Electric Cars: “Refillable Technology”

Researchers at Purdue are working on a new kind of flow battery with a single liquid electrolyte and a replaceable anode. They say it could be cheaper, safer, and more environmentally friendly than conventional lithium-ion batteries.

refillable single flow battery

Credit: Lyna Landis, Purdue Research Foundation

Range and recharging times remain the primary concerns for people who don’t know the difference between an electric car and a toaster. The debate continues to rage between advocates of battery electric cars and those who favor hydrogen fuel cell vehicles, with “fool cell” proponents pointing out it only takes a few minutes to pump hydrogen into a storage tank while it can take several hours to recharge the battery of an electric car. There is some truth to that claim, although it totally overlooks the reality that most electric cars recharge in the garage overnight and never need to visit a charger during a normal day of driving.

Now, researchers at Purdue University say they have a new way of powering electric cars, which they call “refillable technology.” It’s a little like a redox flow battery with one important difference. Instead of using two liquid electrolytes, one negative and one positive, it uses one liquid and a sacrificial anode that is replaced at 3,000 mile intervals. They claim it takes about 5 minutes to fill the onboard storage tank and about 15 minutes to replace the anode.

“The jump that this technology has made in the past two years is a testament to its value in changing the way we power our vehicles,” says John Cushman, a professor at Purdue. “It’s a game changer for the next generation of electric cars because it does not require a very costly rebuild of the electric grid throughout the US. Instead, one could convert gas stations to pump fresh electrolyte and discard depleted electrolyte and convert oil changing facilities to anode replacing stations. It is easier and safer to use and is more environmentally friendly than existing battery system.” The technology has been undergoing testing and development in golf carts and fork lifts since 2017, according to

Cushman and his colleague Eric Nauman have co-founded IFBattery Inc. to commercialize the technology. “The battery does two things: it produces electricity and it produces hydrogen. That is important because most hydrogen powered cars run on a 5,000 or 10,000 PSI tank, which can be dangerous,” said Michael Dziekan, senior engineer for IFBattery. “This system generates hydrogen as you need it, so you can store safe hydrogen at pressures of 20 or 30 PSI instead of 10,000.” Unlike most flow batteries, the new technology requires no membrane to keep different liquids separate.

“Historically, flow batteries have not been competitive because of the low energy density,” Cushman says. “For example, conventional flow batteries have an energy density of about 20 watt hours per kilogram. A lithium-ion battery runs on 130 or 140 watts per kilogram. Our flow battery has the potential to run between five and 10 times that amount.” Whether that is 5 to 10 times more than a traditional flow battery or a lithium-ion battery is not clear in the report. Let’s assume it is the former and not the latter.

“Conventional electric cars like Tesla have lithium-ion batteries that are usually plugged in overnight. Our flow battery uses a water-based single fluid that can run the car like it is a gas engine except it is not burning anything — it’s like a hybrid of a battery and a gas,” Nauman says.

The single fluid technology oxidizes the anode to produce electrons, and through a reduction at the cathode, it generates the current of energy to power vehicles. The oxidant is a macro-molecule that lives in the electrolyte, but is reduced only at the cathode. “We are at the point now where we can generate a lot of power. More power than you would ever guess could come out of a battery like this,” Cushman said.

The spent battery fluids or electrolytes can be collected and taken to a solar farm, wind turbine installation, or hydroelectric plant for recharging. “It is the full circle of energy with very little waste,” Cushman said. “IFBattery’s components are safe enough to be stored in a family home, are stable enough to meet major production and distribution requirements and are cost-effective.”

Battery swapping schemes, new synergies between supercapacitors and batteries, and solid state batteries — all are ideas that could have a major impact on the zero emissions transportation sector. The bottom line, as always, will be cost. Replacing an anode is projected to be a $65 proposition. Rapid oil change facilities could easily repurpose themselves to fill tanks with electrolyte and installing fresh anodes. Conventional gas stations could also transition to the new technology. They already have 100 years of experience with tanks and pumps.

No high pressures are involved, no batteries to store and swap out, no risks of fire after a collision, no multi-million dollar hydrogen refueling stations to build. The single flow concept makes a lot of sense and deserves a closer look. It if can lead to lower emissions from the transportation sector and is affordable, it could make an important contribution to zero emissions travel.


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Steve writes about the interface between technology and sustainability from his homes in Florida and Connecticut or anywhere else the Singularity may lead him. You can follow him on Twitter but not on any social media platforms run by evil overlords like Facebook.


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