Newly launched: “TheBiPo” – thermoforming of bipolar plates for fuel cells

In order to make fuel cells fit for cost-effective mass production, ZBT is investigating new, creative methods. The idea behind the recently launched project “TheBiPo” is to extrude a film from a graphite-polymer compound and then thermoform it into finished bipolar plates.

In the project “TheBiPo”, ZBT, together with the IKT at the University of Stuttgart, is developing the production of a thermoformed bipolar plate (BPP) from thermally and electrically conductive films for use in PEM fuel cells. In the process, a foil made of graphite-polymer compound is to be produced directly from the extruder melt via a wide-slot die and a rolling mill in a continuous process 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 new, particularly thin graphite bipolar plates. Finally, the new BPPs will be characterised in a fuel cell stack test.

The thermoforming of electrically and thermally conductive polymer films offers the potential to significantly reduce the manufacturing costs of PEM fuel cells. Thermoforming can be used to economically produce particularly large-area and thin-walled components, which corresponds to the requirement profile for BPP.

Film extrusion and thermoforming are already mastered in practice with other materials. However, transferring the two technologies to the extrusion and forming of thermally conductive and electrically conductive polymers still involves many open development tasks – especially because of the necessary fine structures. The central challenge: the high viscosity of the highly filled materials used, which leads to altered flow properties compared to the basic polymers when subjected to shear and elongation stress. The complementary competences of ZBT – The Hydrogen and Fuel Cell Center and the IKT Stuttgart complement each other optimally in the implementation of the project.

“Above all, the definition of processing guidelines for the production of BPP by means of extrusion and thermoforming will benefit all relevant companies within the value chain” Paul Stannek from ZBT is certain. Thus, a large potential user group of SMEs can benefit from the results of this project.

Project partner: Institut für Kunststofftechnik (IKT) der Universität Stuttgart

IGF-No.: 22905 N

Grant period: 1 July 2023 to 31 December 2025

Image Collection

Thermoforming plant at IKT Stuttgart (click to enlarge)

Foil production line at ZBT (click to enlarge)

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