UW-Madison Researchers Develop New Flow Battery Tech for Safe, Secure Energy

 University of Wisconsin-Madison researchers have developed a new “flow battery” technology that stores energy in organic salts dissolved in benign water.

The research team has founded a startup company, Flux XII LLC, in Madison to commercialize their long-duration grid energy storage solution with the help of the University’s technology transfer office, the Wisconsin Alumni Research Foundation (WARF). The team hopes to scale and demo their solution with regional partners, which they believe will enable safer and more adaptable clean energy than current grid energy storage products. 

This team’s story began in 2015 when Dr. Wenjie Li started researching aqueous (water-based) redox flow batteries as a chemistry Ph.D. student at UW-Madison.

“I wish my research can really contribute to creating a better world. Having been trained as an electrochemist, redox flow battery is a pathway where I can apply my knowledge and skills to deliver affordable and renewable energy to everyone," Dr. Li said when asked what motivated him to begin research on this topic.

Grid batteries act as an energy insurance plan while increasing savings by optimizing solar (or wind) usage with your utility’s policies. The current market relies on Lithium-ion technologies for emerging grid-scale battery applications, the same technology used in rechargeable computers and phones.

Professor Dawei Feng, who worked on Lithium-ion battery materials as a Stanford postdoc from 2017-2018 and began research at UW-Madison as an assistant professor in Materials Science and Engineering in 2019, says Lithium-ion batteries for the grid “just don’t make sense,” referencing their fire risk and short-duration (6-hour) limitation for end-users. 

Patrick Sullivan, who also performed summer undergraduate research on Lithium-ion batteries in 2018 and has been a UW-Madison Chemistry Ph.D. student in Dawei’s lab since 2019, is passionate about the sustainability of new technologies after having learned to comprehensively evaluate solutions through a UW-Madison Energy Analysis and Policy graduate certificate.

Sullivan notes the supply chain constraints and international mining concerns of Lithium-ion materials.

“There’s really just not enough Lithium for both the grid and electric vehicle markets, and we may just make the global sustainability crisis worse if we aren’t careful," Sullivan said.

With these passions and experiences, the team formed a natural collaboration in 2019 to develop a better grid energy storage solution. Instead of relying on rare foreign metals, the team researches sustainable “organic redox molecules” that can be produced domestically from inexpensive, readily available materials. These organic salts are then dissolved in water and pumped through the battery to store energy while eliminating concerns over fire risk. These materials have been researched in academic labs for the past decade. Still, commercial progress has been slow due to scientific tradeoffs in material properties that are ultimately detrimental to either energy efficiency, energy density, or cost. 

Since 2019, with the help of postdoc synthetic expert Dr. Xiuliang Lyu and funding from WARF, Development to Product (D2P), and UW System grants, Dawei’s University research lab has screened over 500 different flow battery chemistries. The lab has published some of these results in peer-reviewed academic journals and patented related materials that overcome the decade-long performance hurdles. Dawei contributes impactful research progress to their expertise in designing, synthesizing, and evaluating organic materials. At the same time, Sullivan believes their passionate and collaborative team allows them to be more creative. 

Both agree that this is just the beginning, as they are now forming partnerships to move the technology beyond a “lab research project.” In September 2022, the team set up a 1 kW flow battery prototype at UW-Madison, roughly 1,000 times larger than what they typically use to test their materials. With the support of UW-Madison and regional industry partners, the Flux XII team aims to demo a 20 kW flow battery device with a regional customer sometime in late 2023 at a discounted price. This demo – a  “lego block” to building larger systems – will validate this exciting technology to help spur safe and secure clean energy adoption in the region.

Sullivan, striving to take a user-inspired approach as Flux XII CEO, shared his experience engaging Wisconsin communities about their clean energy goals.

“Lots of local governments and businesses are investing in their solar energy to save money long-term and gain independence from fluctuating utility prices,” Sullivan said.

However, Sullivan heard many hindrances to projects with solar intermittency, fears over blackouts, and complex utility policies, which he believes their solution can help address.

“There’s no single ‘silver bullet’ technology that will solve all of your energy challenges. What we have here with our flow battery is just a piece of the puzzle, but it’s one that we believe will make fitting the rest together possible and much easier," Sullivan said.