Presented will be our recent efforts in developing water soluble organic anolyte materials for aqueous flow battery systems. For a family of structurally related molecules, substituent effects on solubilities, electrochemical properties, and chemical stability for a select promising candidate will be discussed. Rational optimization of flow cell conditions including the membrane and electrodes has been achieved for performance improvement. The final anolyte candidate exhibits high solubility in the supporting electrolyte, undergoes two electron redox chemistry, and demonstrates good stability. When coupled with the well-established ferricyanide/ferrocyanide catholyte, the flow battery possesses a high OCV of 1.35 V at 50% SOC and yields stable long-term cyclability.
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