Electrochemical Properties of an All-Organic Redox Flow Battery Using 2,2,6,6-Tetramethyl-1-Piperidinyloxy and N-Methylphthalimide

A novel all-organic redox flow battery employing 2,2,6,6-tetramethyl-1-piperidinyloxy/NaClO 4 /acetonitrile and N-Methyl- phthalimide/NaClO 4 /acetonitrile as catholyte and anolyte, respectively, is investigated by electrochemical measurements. The quasi-reversible and stable redox reactions are tested by cycle voltammetry. The diffusion coefficient of 0.02 M 2,2,6,6-tetramethyl-1-piperidinyloxy and 0.02 M N-Methylphthalimide in the supporting electrolyte are all in the range of 0.7–1.1 × 10 −5 cm 2 ·s −1 at room temperature. Stable charge-discharge curves and high coulombic efficiency (90%) for the first 20 cycles are obtained through charge-discharge test.