In the "TheBiPo" project, the Duisburg Center for Fuel Cell Technology (ZBT) is working with the Institute of Plastics Technology at the University of Stuttgart to develop the production of a thermoformed bipolar plate (BPP) from thermally and electrically conductive films for use in fuel cells with proton exchange membranes (PEM). In this process, a foil made of graphite-polymer compound is to be produced in a continuous process directly from the extruder melt via a slot die and a rolling mill and then transferred to the final component geometry in a subsequent thermoforming process. In addition, the researchers also want to adapt a fuel cell system to the novel, particularly thin graphitic bipolar plates. Finally, the new BPPs are to be characterized in a fuel cell stack test.

And why all this? According to ZBT, the thermoforming of electrically and thermally conductive plastic films offers the potential to significantly reduce the manufacturing costs of PEM fuel cells. Thermoforming allows particularly large and thin-walled components to be produced economically, which corresponds to the requirements profile for BPP. Film extrusion and thermoforming have already been mastered in practice with other materials. However, transferring the two technologies to the extrusion and forming of thermally conductive and electrically conductive plastics still involves many unresolved development tasks - especially due to the fine structures required. The main challenge is the high viscosity of the highly filled materials used, which leads to altered flow properties compared to the base plastics when subjected to shear and tensile stress. The complementary expertise of the ZBT and IKT Stuttgart should complement each other perfectly when carrying out the project.

"Above all, the definition of processing guidelines for the production of BPP using extrusion and thermoforming will benefit all relevant companies within the value chain," Paul Stannek from ZBT is certain. A large potential user group of small and medium-sized companies should be able to benefit from the results of this project.

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