Bipolar Radicals as Active Material for Symmetrical Redox Flow Batteries

Redox-active organic molecules are increasingly investigated as charge-storage materials for redox-flow batteries (RFBs), but material crossover between posolyte/negolyte and chemical degradation are limiting factors in the performance of all-organic RFBs. Bipolar organic radicals can in principle be used to construct batteries with symmetrical electrolyte composition, which mitigates issues due to crossover. This presentation will describe studies to correlate molecular features with battery cycling stability using representative stable organic radicals (Blatter- and verdazyl-type compounds). We illustrate how an understanding of the reaction pathways that contribute to capacity fade can be used to improve battery longevity.