A novel fluorenone compound, 4-oxo-4,8,9,10-tetrahydro-7a,10a-diazacyclohepta[def]fluorene-7a,10a-diium chloride (OTDFL)Cl₂ is constructed as the organic electroactive material for aqueous organic redox flow batteries (AORFB). With the merits of high aqueous solubility and highly reversible electrochemical behaviour, (OTDFL)Cl₂ exhibits excellent volumetric capacity and cycling performance, making it one of the promising candidate electrolytes for AORFB.

https://doi.org/10.1039/D3TA03525E