The electric car’s inability to quickly and easily recharge is one reason why drivers have been slow to embrace electrified transport. But what if a battery could hold as much (or more) energy as gasoline and could recharge with the same amount of effort it takes to fill your tank?
A team of scientists at the Illinois Institute of Technology (IIT) is working to design exactly that. They say their novel variation on a liquid “flow” battery will store 1.5 times the energy of today’s lithium-ion batteries or three times the energy of lead-acid batteries. The battery’s fluid state means it can fit virtually any space, and it can be recharged like a traditional battery or “refueled” like a common gas tank.
What’s more, their battery relies on nanoparticles – very tiny electrochemically active materials – to carry the charge, which the scientists say allows them to pack more energy into smaller and smaller spaces.
In 2014, the team founded a company called Influit Energy to build on their research and to eventually commercialize their battery. Last December, the National Science Foundation awarded Influit a Small Business Innovation Research grant for $225,000 to develop a small prototype.
The search for a better battery is increasingly competitive, with industry heavyweights like Tesla and Chevy competing with nimble startups for energy-storage gold. As costs continue to decline for status-quo technologies like lithium ion, the climb to a true battery breakthrough grows steeper. Still, the Influit team is encouraged by early results and is optimistic there is room in the market for their “nanoelectrofuel flow battery.”
“The beauty of the technology we have is that it’s very flexible,” says Elena Timofeeva, Influit’s chief operating officer and research professor of chemistry at IIT. Influit first aims to develop a battery for small, fleet-based vehicles like forklifts, golf carts, and people movers, but Timofeeva says the same designs and formats can be scaled up for larger vehicles and to store power on a smarter, more dynamic electric grid. “There’s no reason the storage tank has to be a particular shape,” she says.
Best of both worlds?
Flow batteries, in which chemicals dissolved in liquids function as the positive and negative ends of a battery, are not new. Vanadium redox flow batteries have long shown promise as an alternative to the solid-state batteries that dominate the energy-storage world. Last year, Seattle-based UniEnergy Technologies (UET) installed what is believed to be the largest U.S.-based flow battery – a 2-megawatt system for Snohomish County Public Utility District, headquartered in Everett, Wash.
The challenge with flow batteries is that their low energy density means they need a lot of space to pack a significant punch. It’s why they are typically viewed as a solution for stationary storage on the power grid, where size and space is less of a concern.
The Influit team says their battery eliminates this energy-density issue by removing a traditional flow battery’s key limiting factor: solubility. John Katsoudas, Influit’s chief executive officer and senior research associate of physics at IIT, compares it to his morning coffee.
“If I keep pouring sugar into my coffee, at a certain point I’m not going to be able to dissolve more sugar into my coffee,” he explains.
That oversaturation is essentially what happens in a traditional flow battery. Salt is dissolved into an electrolyte to create an ionic solution. The amount of ions in the solution – as well as its energy-storage capability – is limited by the salt’s solubility.
“In our case, we’re not limited by solubility. We’re not dissolving anything. We’re taking the solid-state battery materials, converting them into nanoparticles, and then putting them in a liquid,” Katsoudas adds.
In other words, Influit combines the user-friendly flexibility of liquid batteries with the energy-dense performance of solid-state ones.
The team’s research suggests that the technology will also cost about half the cost per kilowatt-hour of the lithium-ion technology under the hood of today’s electric vehicles. Influit’s proprietary nanoparticles are earth-abundant and non-toxic elements, the company says, and the nanofluid’s cooling properties keep it from overheating.
Perhaps most attractive for drivers, the battery can be recharged either by plugging it into the grid or by swapping out the spent nanoelectrofuels for charged ones – not unlike filling up a gas tank.
The path to a smarter, cleaner energy system is paved with promises of battery breakthroughs that ultimately fall short. In many cases, designs that look good on paper fail to translate to real-world applications. Other times a coin-sized prototype performs marvelously but falls apart when scaled up to power a car.
For Influit, which is hoping to develop a 1.2-volt cell within a year, it’s too soon to tell what kind of impact their technology will have. Even if Influit’s battery proves susccessful at the car-size scale, it would still require the kind of charging-station/re-nanoelectrofuel-ing infrastructure buildout that contributes to some drivers’ “range anxiety.”
But Carlo Segre, Influit’s chief technology officer and Duchossois Leadership Professor of Physics at IIT, says that just building a dramatically faster-charging and more energy-dense battery would have a lot of value – both in transportation and in the growing area of small-grid-storage applications like home battery systems. Katsoudas agrees:
“The goal is to make a better battery, sell it on its own merits, and then start introducing these advanced features that no other battery can take advantage of.”