The inhabitants of Graz are developing vanillin-based electricity storage devices

Reliable energy storage systems that have been sustainably produced themselves are a basic requirement for the use of renewable energy sources. Liquid battery technology – also known as redox flow batteries – has received renewed attention in recent years. Their efficiency of more than 75 percent, high life expectancy, cycle stability and at the same time low tendency to self-discharge are major advantages. However, they have the disadvantages that escaping electrolyte can have serious ecological consequences, metals are expensive and usually have a poor environmental balance.

Stefan Spirk and his team at the Institute for Biobased Products and Paper Technology have already succeeded in recent years in making redox flow batteries more environmentally friendly: they found a way to do this, producing their core element – the liquid electrolytes – from vanillin produce waste from lignin. According to TU Graz, vanillin can be produced using mild and green chemistry without the use of toxic and expensive metal catalysts. The process works at room temperature and has already been patented.

In his start-up Ecolyte, Spirk is now working with institutes of the Graz University of Technology and other project partners to make the vanillin electricity storage system as sustainable as possible in all components and processes: in addition to vanillin as a storage medium, the focus is also on the membrane, the electrode and the controller. “In ‘VanillaFlow’ we are developing radically new approaches to integrated energy storage that combine artificial intelligence and machine learning with flow battery technology to replace the currently deployed, unsustainable and critical raw materials in flow batteries with readily available renewable starch-based materials and lignocellulose,” say the project managers at the Graz University of Technology.

AI searches for the ideal composition
“VanillaFlow” also uses the possibilities of machine learning. According to a statement from the Technical University of Graz, this means predictions for models of promising vanillin compounds can be made more quickly. They must be developed and tested in the laboratory with the Institute of Molecular Biotechnology in order to ultimately find the ideal composition of the storage liquid. Ulrich Hirn (Institute for Biobased Products and Paper Technology) is in charge of project management at the Graz University of Technology. Together with TU Darmstadt, he also supports the Ecolyte team in further developing the membranes.

Durable components
Here too, the aim is to replace earlier materials with more sustainable ones. A paper version has already been made for this, which is now being further developed with researchers from TU Darmstadt. For the electrode, one would like to use a carbon fleece, which should offer less resistance through compression and form fewer deposits. New coatings and treatments strive for even better performance.

The components are tested in interaction using a digital twin. At the same time, the control of the memory is being further developed. According to the Technical University of Graz, the entire research is accompanied by toxicological studies and techno-economic assessments. The first memory prototype, co-designed by AI, will be integrated into the Graz University of Technology network. Initially, a storage capacity of ten kilowatts must be possible for this, but the capacity can be scaled up as desired for future applications.