Riboflavin Derivatives for Sustainable Redox Flow Batteries

Demand for renewable energy, electric vehicles, and sustainability is rapidly increasing, and this demand for more sustainable solutions is driven by the progressively increasing climate issues worldwide. Redox flow batteries (RFBs) are found within renewable energy sources such as wind farms, hydroelectric, and solar power plants where they aid in storing power produced from these sources and distributing it out to the grid when required. Of these, the most commonly used is the vanadium redox flow battery (VRFB) which have been demonstrated to work on an industrial scale since the mid 1980s. However, these systems are now majorly outdated and use harmful and toxic active compounds employed as their electrolytes. These cells can be replaced by newer, more sustainable systems using organic compounds as their redox active electrolytes. With organic redox flow batteries (ORFBs) the scalability and tuneability can go a long way, as the organic active material can easily be adapted to required specifications and parameters a cell requires. This project targeted the synthesis of novel, redox active organic molecules from a biological source (riboflavin) tailored to work in acidic aqueous conditions, with the goal of them being used as a stable and robust electrolyte within a flow cell. The target molecules were synthesized and studied using electrochemical testing methods including cyclic voltammetry (CV) and flow cell testing to evaluate them as potential electrolytes in an RFB environment, with a sulphonated derivative of riboflavin identified as a promising lead candidate. The research reported here suffered from multiple issues regarding synthesis complication and equipment failure; 5 these were overcome by adopting alternative methods and principles, as well as a collaboration with an external research group working on similar flow cell studies.