Renewable energies are clean, abundant alternatives to traditional fossil fuels but are also limited by their intermittency causing grid instability. Electrical energy storage is a promising solution to address the challenges. Our primary research focus is on the development of energy-dense, efficient, stable redox flow batteries to achieve cost-effective grid storage. Current interests include design, preparation and evaluation of critical flow battery component materials, such as redox-active materials, membranes and electra-catalysts, in single cells and multi-cell stacks. The research themes lie in three aspects: materials development, fundamental structure-property understandings, and system integration and prototyping. A natural extension is to utilize the redox flow battery set-up for other applications such as water purification.
Organic redox-active materials are promising materials because of their structural diversity and tailorability promising to offer facile property tuning for both aqueous and non-aqueous flow batteries. We have identified a variety of promising organic candidates including phenazine, carbonyls, ferrocene, nitroxyl radicals, metal-coordination complexes, etc. The research tasks include structural modification to achieve high solubility and stability and meanwhile combined characterizations to understand property-controlling factors.
Ion-Conductive, Perm-Selective Membranes
Ion-conductive, perm-selective membranes are the key to achieving high efficiency and long stability in redox flow batteries. We have evaluated commercial and self-made ion exchange membranes, porous separators and ceramic separators in both aqueous and non-aqueous flow batteries. But these membrane materials still suffer from respective issues. The research goal is rational membrane structure design to create fast, selective ion transport channels.
The lack of drinkable water has become a life-threatening crisis for many people in the world. The current method for mass production of clean water is reverse osmosis but is quite energy-intensive. We are investigating using redox flow batteries as an approach for desalination of seawater. The main focus is on the development of stable, cost-effective redox-active materials for this purpose.