Computational screening of organic molecules as redox active species in redox flow batteries

In general, redox active species with a wide redox window and high solubility are necessary to increase the energy density of redox flow batteries. We employed the following three screening factors aimed at identifying such new redox active materials: oxidation potential, reduction potential, and solvation energy. Of the 106 organic molecule candidates, we managed to obtain five molecules that satisfy the screening criteria, namely, trifluoromethoxy-trifluoromethoxybenzylbenzene, bromo-methoxybenzonitrile, dimethoxy-octafluorobiphenyl, chloro-methoxypyridine, and dimethoxyphenyl-ethanone. The characteristics of each molecule are then examined, which enable us to suggest two promising redox active materials for redox flow batteries: fluoro-methoxybenzonitrile and dimethoxy-octafluorobiphenyl.