Artificial Bipolar Redox-Active Molecule for Symmetric Nonaqueous Redox Flow Batteries

We synthesize a covalently linked bipolar molecule 1-(2-(4-methoxy-2,5-dimethylphenoxy) ethyl)-1′-methyl-[4,4′-bipyridine]-1,1′-diium hexafluorophosphate (VIODAMB) and apply this new compound to a nonaqueous organic redox flow battery (NAORFB) as both the anolyte and catholyte. We demonstrate that this symmetrical electrolyte can mitigate the cross-contamination issue in the flow battery. The compound exhibits an enhanced solubility of 0.66 M in acetonitrile. The flow cell delivers a capacity retention rate of 80% and an energy efficiency of 85% over 35 cycles at a current density of 1.5 mA cm-2 in the cycling test. © 2021 American Chemical Society.