A Novel Flow Battery Using Quinoxaline Derivatives As Redox Couple

New and renewable energy resources are being developed to reduce the use of fossil fuels and decrease the greenhouse gas emission. Energy storage is now seen as the opportunity for improve energy efficiency and utilize discontinuous clear energy like the wind and solar power. Redox flow battery is now leading the way in electrochemical energy storage system for its low cost, flexibility and high efficiency. Flow batteries are almost metal based of which the most widely used is all vanadium redox flow battery. A breakthrough by using metal-free organic-inorganic redox couples as active materials. 9,10-anthraquinone-2,7-disulphonic acid (AQDS) undergoes extremely rapid and reversible two-electron two proton reduction on a glassy carbon electrode in sulphuric acid had made[1]. And a quinoxaline-derivatives as initial low-potential materials had employed and showed good columbic and energy efficiency[2].

Quinoxaline is a promising active material for flow batteries due to its low molecular weight, high solubility and ability to transfer two electrons per pyrazine ring. In this study, quinoxaline-derivatives were studied, and the reduction potentials including hydroxyquinoxaline and methylquinoxaline are calculated with DFT, while solvation free energies calculated by COSMO model. A better reversibility as well as rapid kinetics have been observed. The most of the derivatives are highly soluble in aqueous or non-aqueous solutions and the reduction potentials are relatively low (~-0.3V) indicate that can be combined with the Br₂/Br^- couple, which would show high energy efficiency. Electrochemical properties of quinoxaline-derivatives with various concentration, different additions, in different solvents will be tested which would involving Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Rotating Disk Electrode and Rotating Ring-Disk Electrode (RDE and RRDE). The battery performance will be tested employing quinoxaline-derivatives and Br₂/Br^-as cathode and anode redox couples, respectively.

Key words:flow battery, redox couple, quinoxaline

Acknowledgment:This work was supported by the National High Technology R&D Program of China (2012AA053401)

References

[1] B. Huskinson, M.P. Marshak, et al. A metal-free organic––inorganic aqueous flow battery. [J] Nature. 2014, 505: 195-198.

[2] Fikile R. Brushett, John T. Vaughey, and Andrew N. Jansen. An All-Organic Non-aqueous Lithium-Ion Redox Flow Battery. [J] Adv. Energy Mater. 2012, 2, 1390–1396.