Identification of new redox compounds is essential for the design of new improved redox-flow batteries (RFBs). Phenazines are an emerging family of organic compounds in electrochemical energy storage applications. They are a promising candidate for high-density energy applications, because of their multi-redox activity, their low-toxicity and their structural diversity. By applying high-throughput density functional theory calculations, we investigate the redox-potentials of ~200 phenazine derivatives in aqueous and non-aqueous media containing various electron-donating (EDG) or -withdrawing (EWG) groups at different positions. We explore the redox behavior of phenazine-derivatives in aqueous and non-aqueous media, where two redox pathways exist: i) the coupled 2-electron and 2-proton reduction in aqueous media, and ii) the 2-electron reduction in two steps in aprotic media. By using EDGs/EWGs, we are able to shift the potential towards more negative/positive values compared to the parent phenazine. We identify promising candidates for both the negative and positive sides of the RFBs. The results reveal the importance of both the functional group and the position on the redox potential.

New insights into phenazine-based redox flow batteries by using high-throughput density functional theory modeling

ACS Spring Meeting 2021

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