Utilization of Carbon Nanotube Based Catalyst for the Performance Enhancement of Aqueous Organic Redox Flow Battery

Abstract

Alloxazine and ferrocyanide were introduced as redox couple for aqueous organic redox flow battery (AORFB). Alloxazine was further modified by carboxylic acid (COOH) (COOH-alloxazine) to increase the aqueous solubility. For improving the performance of AORFB, the redox reactivity of the rate determining reaction (RDR) should be enhanced. Carboxylic acid group doped carbon nanotube (CA-CNT) catalyst was used for increasing the redox reactivity of RDR. The CA-CNT induced a better redox reactivity of COOH-alloxazine that was RDR because of the function of COOH as a proton donor. The strengthened hydrophilic property of COOH-alloxazine and the increased number of active sites were another reasons for causing the better redox reactivity. Regarding AORFB full cell testing, when the CA-CNT was adopted as the catalyst for the negative electrode, the performance of AORFB increased. According to the detailed results, charge/discharge overpotential and IR drop potential were enhanced, coulombic and energy efficiencies also increased, and discharging capacity reached to the similar level to that of vanadium redox flow battery. Reference [1] "Effect of carboxylic acid doped carbon nanotube catalyst on the performance of aqueous organic redox flow battery using the modified alloxazine and ferrocyanide redox couple", W. Lee, B.W. Kwon and Y. Kwon, ACS Applied Materials & Interfaces, 10, 36882-36891, 2018