To achieve this goal, the project was divided into the areas of foil production, adhesive development, investigation of the contacting and application processes, and the design and development of a functional bipolar plate including tool-free manufacturing.

Within the project duration, a total of 13 polymer types, ten graphites and three conductive carbon blacks were investigated for their suitability for substrate production as part of the foil development at the ZBT. In total, foils were produced and characterized from more than 120 compound formulations. At the end of the project, the volume resistivity of a single foil was 19 mΩcm², almost on a par with the injection molding reference.

The adhesive development at ifs has shown, that increasing the filler content does not automatically reduce the volume resistivity. Rather, a high filler content in conjunction with sufficiently high compression during curing leads to a reduction in resistances.

For functional testing, a single-cell fuel cell stack with two 4-layer foil bipolar plates was set up and successfully tested in a 400-hour endurance test.

In conclusion, a functional setup was achieved and operated in which flexibility can be exploited to the full extent - flexible foils are combined with flexible manufacturing processes.  Due to the laser system technology used, the results for foil cutting can be used by SMEs without high costs for individual forming tools. The roller application of the adhesive has great potential for automation with low cycle times and also addresses corresponding SMEs in manufacturing technology.

For detailed information, please refer to the joint final report to be published soon.

Research association: Schweißen und verwandte Verfahren e.V. des DVS

Project partners

• TU Braunschweig, Institute for Joining and Welding
• Zentrum für BrennstoffzellenTechnik GmbH, Department of Fuel Cells and Stacks