New large-size bipolar plates for redox-flow batteries produced with the extrusion process
The aim of this project was the development of materials as well as the manufacturing process of novel large area bipolar plates for vanadium redox flow batteries (VFB). A plate size of at least 1 m² was the goal, with the preferred area ranging from 2 m² to 3 m². The technical target was to develop a bipolar plate, which has a sufficient mechanical stability and tightness as well as a high electrical conductivity.
During the project, material investigations employing various in-situ and ex-situ methods were conducted at ICVT. For this purpose, the new bipolar plate materials were examined concerning their uniformity by means of conductivity mapping. Furthermore, the corrosion resistance in the electrolyte was ensured. The direct use of the bipolar plates in VFB was also investigated in parallel full cell tests.
In addition to the experimental work, the properties of the large cells respectively large electrodes/plates were investigated on a model basis. Since the scale-up of VFB by means of an enlargement of the active cell area leads to increased pressure losses, the use of flow fields was investigated, which preferably had to be extrudable.
After the successful completion of the described project, the succeding project Re³dOx started on 01.09.2019.