December 2020

In recent years, organic redox flow batteries (RFB) have increasingly become the focus of attention as large-scale energy storage systems, since they do not contain toxic and rare metal ions compared to the established vanadium RFB. Due to this, the demand for new organic active materials, which are used as catholyte or anolyte in organic RFB, is increasing. The long-term stability of the organic active materials is crucial for a possible commercial success of RFB. Our research group is focusing on the characterization of the performance and stability of organic active materials for RFB in operation. The picture shows an example of the results obtained with a diazanaphthoquinone (synthesized by AG Wegner at the JLU; cooperation within a project funded by the BMEL). The diazanaphthoquinone (top) was measured using an operando UV/Vis cell (left), while electrochemical measurements (right) were performed simultaneously. The UV/Vis measurements are used to identify products and degradation products, whereas long-term electrochemical measurements allow to determine the kinetics of the occurring degradation reactions. Overall, our group always relies on a powerful combination of analytics (operando, in-situ and ex-situ) and theoretical considerations to advance the understanding of organic active materials for RFB. (Image by: Dominik Emmel and Simon Kunz)