Researchers Develop a Stable Catholyte for Aqueous Organic Redox Flow Batteries

Researchers at the University of Akron, United States, have asserted that they have developed the most stable catholyte (positive electrolyte) for aqueous organic redox flow batteries (AORFB) and demonstrated cells that could keep 90% of stored energy capacity over 6,000 cycles and 16 years of uninterrupted service.

The researchers collaborated with scientists at Pacific Northwestern National Laboratory to develop the stable catholyte.

The researchers said low-cost, scalable redox flow batteries are among the most suitable storage technology. However, existing redox flow batteries use high-cost and environmentally hazardous electrolytes.

Recently, water-soluble organic materials have been proposed as future electrolytes in redox flow batteries obtained from renewable sources and manufactured at a low cost. However, the lack of stable water-soluble electrolyte materials, particularly catholyte, is a major barrier for AORFBs.


To develop a water-soluble catholyte and enhance its energy density in water, the researchers changed the symmetry of molecules instead of attaching a hydrophilic functional group to improve molecules’ energy density. The researchers plan to design new materials that could further mature redox flow batteries with this new design strategy.

Yu Zhu, a professor at the University of Akron’s School of Polymer Science and Polymer Engineering, said, “Development of high-performance redox flow batteries will enrich the category of energy storage systems, therefore largely improving the usability of electricity powered facilities, such as vehicles.”

“To significantly improve the performance of aqueous organic redox flow batteries, the urgency of developing a new catholyte is crucial,” Zhu said.

The researchers have submitted a patent application for this new technology. The scalability of the materials would be further studied at Akron PolyEnergy, a spin-off company of the University of Akron that focuses on developing materials in energy storage devices, including lithium-ion batteries and flow batteries.

Last year, researchers at Friedrich Schiller University developed a new polymer electrolyte for redox flow batteries that enhances its efficiency and heat-resistance capacity. According to the research report, the new polymer electrolyte is soluble in water and can be used in aqueous electrolytes. The new polymer can also store electricity as it contains ions.

Mercom had earlier reported that researchers at TU Graz University developed a redox flow battery that utilizes conventional vanillin instead of liquid electrolyte, making the battery more environmentally friendly. The researchers refined the common flavoring substance vanillin into a redox-active material with the help of mild and green chemistry without using harmful and costly metal catalysts.