Research published by scientists in the US indicates an organic molecule used in dyes and antibiotics “may be the key to less expensive, more efficient redox flow batteries”.
The scientists at the Department of Energy’s (DOE) Pacific Northwest National Laboratory (PNNL) team have developed a “highly reversible, water soluble material based on phenazine”— that could serve as an alternative to vanadium used in grid-scale batteries.
“This is a major development for organic flow batteries,” said Imre Gyuk, director of energy storage at DOE’s Office of Electricity, which supported the PNNL team’s research.
“There is much interest around the potential for water soluble, organic redox materials as an alternative to vanadium-based batteries,” Gyuk said. “However, the problem is getting the materials to actually dissolve in water and maintain the desired electrochemical properties.”
The PNNL team, led by chief scientist Wei Wang, knew that phenazine, a naturally occurring compound, possessed “the needed redox reactions but was not water soluble”.
So the scientists developed a method of chemically modifying phenazine, producing a water-soluble derivative that also optimises its redox properties. When dissolved in the electrolyte solution, 90% of the dissolved phenazine was available to carry energy, according to the PNNL team.
Wang said the team needs to conduct a cost analysis, but “phenazine precursor chemicals are readily available and inexpensive”.
“The results are promising,” said Wang. “We have not only developed a viable alternative to vanadium, we have developed a structured, virtual screening approach that will help us identify new promising materials.”
PNNL will continue testing a phenazine-based anolyte (negative electrolyte) and plans to develop a corresponding catholyte (positive electrolyte). Combined, the solutions could lead to new type of redox flow battery, PNNL said.