Improve the Kinetics of the Ketone-based Aqueous Organic Redox Flow Batteries

Redox flow batteries have a unique architecture that potentially enables cost-effective long-duration energy storage to address the intermittency introduced by increased renewable integration for the decarbonization of the electric power sector. Targeted molecular engineering has demonstrated electrochemical reversibility in natively redox-inactive ketone molecules in aqueous electrolytes. Yet, the kinetics of fluorenone-based flow batteries continue to be limited by slow alcohol oxidation. We show how strategically designed principles can accelerate alcohol oxidation and thus enhance battery kinetics. Rationally designed fluorenone-based flow battery electrolytes demonstrate enhanced rate capability, high battery capacity, and record-breaking long cycling. This study opens a new avenue to improve the kinetics of aqueous organic flow batteries.