Harvard Researchers Report Long-Life Breakthrough For Flow Batteries

June 13th, 2017 by Steve Hanley

Researchers at Harvard’s School of Engineering and Applied Sciences claim they have made a breakthrough in flow battery technology in the laboratory that could lead to lower-cost flow batteries that are nontoxic and last much longer than conventional lithium-ion batteries.

The research may not do much to lower the price of electric cars. Only NanoFlowcell has thought about flow batteries for automotive use. But it could be hugely important when it comes to creating the grid-scale battery solutions needed to drive the renewable energy revolution forward.

First, a disclaimer. “There’s many a slip ‘twixt the cup and the lip,” my old Irish grandmother was fond of saying. We know that what works in the lab doesn’t always translate well into the commercial world. Aquion Energy, a company heavily invested in flow battery technology, went bankrupt earlier this year.

Sometimes it’s more a matter of timing than technology. But if ever the time was right for innovative grid storage solutions, it is now. The implications for a more distributed energy grid are enormous.

Long Battery Life Is Key

The research, published in the prestigious ACS Energy Letters journal, promises a non-corrosive, non-toxic battery with exceptionally long life and low costs of production. The most exciting news is that the new flow battery loses only 1% of its capacity for every 1000 charge/discharge cycles. “Lithium ion batteries don’t even survive 1000 complete charge/discharge cycles,” says professor Michael Aziz, one of the lead authors of the report.

Professor Roy Gordon, another author of the report, adds, “Because we were able to dissolve the electrolytes in neutral water, this is a long-lasting battery that you could put in your basement. If it spilled on the floor, it wouldn’t eat the concrete and since the medium is noncorrosive, you can use cheaper materials to build the components of the batteries, like the tanks and pumps.”

What the researchers don’t say, but which is vitally important, is that the new battery would not carry the risk of fire and/or explosion associated with lithium ion batteries and would probably not need expensive cooling and shielding systems either, further reducing costs.

Goal Is Less Than $100 Per kWh

The US Department of Energy has made the development of batteries that cost less than $100 per kilowatt-hour one of its most important goals. That’s the price at which stored energy from renewable sources such as wind and solar becomes competitive with traditional sources of energy like fossil fuels and nuclear plants. “If you can get anywhere near this cost target then you change the world,” Aziz says. “It becomes cost effective to put batteries in so many places. This research puts us one step closer to reaching that target.”

In an effort to minimize how quickly organic compounds in conventional flow batteries break down and lose their effectiveness, the researchers turned to ferrocene, a molecule well known for its electrochemical properties, as the primary component of the positive electrolyte.

“Ferrocene is great for storing charge but is completely insoluble in water,” says Eugene Beh, one of the researchers and report author. “It has been used in other batteries with organic solvents, which are flammable and expensive.” The team was able to devise a way to make ferrocene soluable in water. “Aqueous soluble ferrocenes represent a whole new class of molecules for flow batteries,” said Aziz.

Making the two electrolytes that comprise the battery less corrosive means the membrane that separates them can be made from far less costly materials, further lowering the price of the completed battery. Harvard has filed for a number of patents stemming from the research and is already seeking commercial partners to bring the technology to market.

Source: Electric Cars Report











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