Crossover-free hydroxy-substituted quinone anolyte and potassium ferrocyanide catholyte for aqueous alkaline organic redox flow battery

Abstract

Among the aqueous organic redox flow batteries, quinone derivatives based redox molecules are commonly explored, due to their facile electron transfer ability. In this work, we have screened three redox active quinones (anthrarufin (AN), naphthazarin (NN), and juglone (JN)) for anolyte and cells were fabricated against K4Fe(CN)6 catholyte. The anolyte with more number of aromatic rings, i.e., AN is capable of better delocalizing the electrons and show more negative redox potential, thereby enhancing the operating voltage of the battery. AN exhibited a single step two-electron reduction process and delivered a capacity of 1.32 Ah L−1 at 20 mA cm-2 current density.