An Organic Electroactive Material for Flow Batteries

An inexpensive, abundant electroactive organic molecule, 3,4-Dihydroxy-9,10-anthraquinone-2-sulfonic acid (ARS) is proposed to serve as the redox active material in the negative side of flow batteries . The electrochemical characteristics and mass transport properties are discussed in this work. The diffusion coefficient of ARS is calculated as 2.14   ×   10 −6   cm 2   s −1 , and the kinetic rate constant of ARS is further measured as 3.6   ×   10 −3   cm   s −1 , which is faster than other metal redox active species used in flow batteries , such as Fe 3+ /Fe 2+ , Cr 3+ /Cr 2+ , VO 2 + /VO 2+ , and Ce 4+ /Ce 3+ . Unlike metal redox materials, ARS will not suffer from the resource constraints. Combining 1,2-benzoquinone-3,5-disulfonic acid (BQDS) as the positive electroactive species and H 2 SO 4 solution as the supporting electrolyte , the different charging-discharging behavior and the polarization curves exhibited a good performance with our laboratory design flow cell. It can be concluded that the ARS presents a unique opportunity for developing a promising and cost-effective alternative for metal-free flow batteries.