Design and Synthesis of Sustainable Electrolytes for Redox Flow Batteries Based on Abundant Metals

Redox flow batteries (RFB) are a promising technology for stationary energy storage systems which will become a real necessity as we transition to a low-carbon energy landscape that relies more heavily on intermittent renewable energy. In such RFBs, the electrical energy is stored in liquids through redox reactions of dissolved redox couples at electrodes. The choice of electrolytes is a key factor in the costs, durability and sustainability of these batteries, and currently prohibits the wider implementation of this promising technology. Suitable, sustainable electrolytes must have a good balance between stability and solubility of the ions in the oxidation states involved, enable rapid and reversible electrode reactions and must consitst of compounds with high availability and affordability of raw materials. Chelation of metal complexes has demonstrated the ability to modulate redox potential and increase redox kinetics and solubility to generate high performance, low cost RFBs.

This PhD project will focus on the design and synthesis of chelating ligands, their complexation with earth abundant metals as redox couples as electrolytes for RFBs. Based on a proof-of-concept, and with the help of computational modelling (Density Functional Theory, DFT), a range of iron, cerium, manganese and vanadium redox couples with suitable potential difference and reversibility in charge/discharge experiments will be synthesised. According to the criteria for the electrolyte, these need to form stable solutions of abundant metals (Fe, Mn, Ce), using non-flammable, non-toxic solvents and complexing agents which result in high solubility and redox potentials in a suitable range.

By using new redox-couples containing redox-stable metal complexes consisting of earth-abundant metals such as iron, manganese or cerium, electrolytes with performances similar to vanadium but at lower costs can be synthesised. The intention is to explore new electrolyte chemistries and redox couples with non-vanadium chemistries. Thereby, a range of organic ligands will be designed assisted by computational methods (DFT calculations), and the redox potentials of the metal complexes will be determined, resulting in a ‘map’ of complex structures vs. redox potentials. In particular, iron, cerium and manganese and vanadium have redox potentials within the right margin which can form long-term stable complexes; however, the structure / property relationship regarding their electrochemical potential is currently not fully understood. Introducing ligands can alter the redox potentials, and therefore the cell voltage of the RFB. The new electrolyte solutions will be characterised using electrochemical characterisation methods, ranging from CVs and EIS to the characterisation of the ion mobility in the electrolyte.

The PhD student will work in close collaboration with the industrial partner (Shell) and will have the possibility to spend up to 6 months at the Shell Technology Centre Amsterdam (STCA), Netherlands (funded). The student will work there closely with a team of international redox flow battery experts and will have access to Shell’s high-end, state-of-the-art energy and lab facilities. The PhD student will present and discuss progress in monthly meetings with the academic supervisory team and a team of energy storage experts from Shell. These meetings will provide additional technical feedback and an industrial perspective to the research.

The ideal candidate should enjoy working in a multi-disciplinary field of energy storage that ranges from inorganic chemistry, materials chemistry to analytical techniques. Team-working qualities, clear communication skills and the ability to learn and develop new techniques are key for a successful candidate.

For more information please contact: Professor Peter Nockemann ([Email Address Removed]) or Dr Oana Istrate ([Email Address Removed])

Applications must be submitted online, by the deadline, using the QUB Direct Application Portal https://dap.qub.ac.uk/portal/user/u_login.php