Reversible ketone hydrogenation and dehydrogenation for aqueous organic redox flow batteries

TLDR

Flow batteries store catholyte and anolyte in separate tanks and circulate them through electrodes separated by a membrane, but suitable redox molecules for large‑scale grid storage remain limited. The authors engineered 9‑fluorenone derivatives and evaluated them in an aqueous redox flow battery that relies on reversible ketone hydrogenation and dehydrogenation. These reactions provide a two‑electron redox process that operates in air at 50 °C, offering advantages for practical applications. Science, abd9795, this issue p.

Abstract

Engineering suitable redox molecules In a flow battery, catholyte and anolyte are stored in separate tanks, and pumps are used to circulate the fluids into a stack with electrodes separated by a thin membrane. Such batteries are ideal for large-scale grid storage applications; however, suitable redox molecules are currently limited. Feng et al. used “molecular engineering” to modify an inexpensive precursor (9-fluorenone) as the basis for an organic-based redox flow battery (see the Perspective by Hu and Liu). The authors tested a series of variant molecules in a redox flow battery in which the reactions involve reversible ketone hydrogenation and dehydrogenation in an aqueous electrolyte. These reactions have advantageous features, including two-electron redox and operation in air and at elevated temperatures (50°C), that are more suitable for real-world applications. Science , abd9795, this issue p. 836 ; see also abi5911, p. 788