Aqueous soluble organic (ASO) redox-active materials have recently shown great promise as alternatives to transition metal ions employed as energy-bearing active materials in redox flow batteries for large-scale energy storage because of their structural tunability, cost-effectiveness, availability, and safety features. However, development so far has been limited to a small palette of organics that are aqueous soluble. This presentation will use fluorenone as an example to showcase how a natively redox-inactive molecule can be tuned to possess two-electron redox reversibility through hydrogenation and dehydrogenation. The modified fluorenone molecules demonstrated high energy density and recorded stable cycling. Furthermore, research has shown the kinetics of the redox reactions; thus, the system rate capabilities can be improved by incorporating suitable hydrogen acceptors that regulate the proton pathway for a faster redox reaction.Reference: Feng et al., Science 372, 836–840 (2021), Feng et al., submitted, 2022