The development of materials with precisely tuned electrochemical and physical properties is critical in enabling nextgeneration energy technologies. One example appears in redox flow batteries (RFBs), which offer the potential to deliver a low-cost and reliable energy storage solution at the grid-scale. While vanadium-based RFB chemistries are currently the most well-studied, battery formulations using organic molecules as the active species are a promising alternative as they are domestically manufacturable, decoupled from markets for transition metals, and have a lesser ecological footprint. The stability window of the solvent determines the desired electrochemical potential for both anode and cathode half-reactions: for water-based batteries, this dictates a maximum thermodynamically stable voltage of 1.23 V at 25°C, although in practice voltages of approximately 2.0 V are possible due to the slow kinetics of hydrogen evolution on carbon electrodes. A wide range of organic redox couples exist and have been explored as charge carriers in flow battery applications. Among these, persistent organic radicals are a promising class of active species with highly reversible redox processes. These molecules have an unpaired valence electron that can either be donated or paired with an accepted electron to form a closed-shell species. However, due partly to their unique and complex chemistry, relatively few stable radical-containing materials have been explored. As a result, most studies have focused on chemical modifications of a handful of well-known stable radical scaffolds, primarily via mechanism-based approaches that identify optimal side-chains to improve performance such as increasing solubility or limiting possible decomposition reactions. The scarcity of radical scaffolds complicates the tuning of their physical and electrochemical properties to meet the strict demands of high-performance, low-cost RFBs. For example, TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl) is currently one of the best organic catholyte candidates due to its persistence and ability to undergo reversible one-election oxidation (Fig. ). However, water-soluble TEMPO derivatives remain uneconomical, with a low oxidation potential of +0.8 V vs. Standard Hydrogen Electrode (SHE) compared to the thermodynamic limit of +1.23 V in water imposed by the oxygen evolution half-reaction. Viologen derivatives have similarly been explored as anolyte materials due to their highly reversible +1/+2 redox couple with a standard reduction potential of -0.45 V vs. SHE. However, with a molecular weight of 257 g/mol (vs. 156 g/mol for TEMPO), batteries based on methyl viologen are unlikely to satisfy capital cost requirements for commercial viability. Additionally, the use of separate electrolytes for the anode and cathode results in capacity fade with chemical cross-over driven by concentration gradients. The discovery of new stable organic radical scaffolds may therefore unlock performance and cost targets unachievable with current materials.