With the recent increase in renewable energy production demand for high-performance energy storage devices has risen. As part of an effort to overcome these storage challenges, University of Wisconsin–Madison researchers have developed a novel additive that improves bromide aqueous flow battery performance.
“Bromide-based aqueous flow batteries are a promising solution, but there are many messy electrochemical problems with them. That’s why there’s no real successful bromide-based products today,” said Patrick Sullivan who graduated from UW–Madison with a PhD in chemistry. “Yet, our one additive can solve so many different problems.”
Successful implementation of aqueous flow batteries could make grid-scale energy storage safer and cheaper than the current lithium-ion battery packs currently in use. Since aqueous flow batteries circulate ions dissolved in water, they are considered safer, more scalable, and more sustainable than their lithium counterparts.
Current aqueous flow batteries rely on vanadium ions which are expensive and hard to source, hindering the widespread commercialization of aqueous flow batteries. A promising alternative, bromide, is widely available and cheap but can create problems including a lack of efficiency in aqueous flow batteries.
To remedy this, the researchers set out to develop a complexing agent. Using molecular design they engineered over 500 candidate molecules, ultimately synthesizing and testing 13 of them.
In their research, published in Nature, the researchers demonstrated that these water-soluble additives solve the flow battery's largest problems. More importantly, the additives greatly improve the battery's performance by boosting efficiency and increasing the longevity of the system.
“Our devices with the additive functioned without decay for almost two months compared to ones without it, which typically fail within a day,” said Dawei Feng, an assistant professor of materials science and engineering at UW–Madison. “This is important because for green energy storage, you want to use it for 10 or 20 years.”
The team intends to refine the additives for use in bromide and iodide flow batteries as well as assess their commercial viability.