A nonaqueous organic redox flow battery using multi-electron quinone molecules

Organic redox flow batteries are promising energy storage devices due to their moderately low-cost and scalability. This paper introduces a new multi-electron redox active material, tetra-aminoanthraquinone (DB-1) that is capable of forming cations with an oxidation state of 4+, yielding one of the highest electrode potentials (up to 4.4 V vs. Li) and the largest multi-electron transfer (ca. 4 e- ). Computational calculations using density functional theory reveal that the DB-1 molecule has narrower HOMO-LUMO band gaps ( 3 eV) than similar molecules ( 3.9 eV). Stable charge-discharge cycling performance of this organic molecule is observed with high energy efficiencies (ca. 71%) at a relatively high current density of 20 mA cm-2 over 50 cycles, demonstrating the marked potential of DB-1 for future redox flow battery applications.