Materials research Large hybrid compound bipolar plates make heavy-duty trucks roll greener

Half a dozen experts have come up with a way to make heavy-duty transport more environmentally friendly. The answer is: stable, affordable, and powerful fuel cells ...

Heavy transport, particularly truck traffic, contributes significantly to global CO₂ emissions. In Europe, about 30 percent of emissions in the mobility sector are attributed to road freight transport. So far, fossil fuel engines dominate because battery-electric alternatives imply an enormous additional weight due to the required accumulators. In the "HyCoFC" research project, industry and research partners are therefore deliberating on how to develop bipolar plates for durable, cost-effective, and high-performance fuel cells intended specifically for heavy-duty applications. Not to forget the long charging times and high currents required in this logistics sector. However, fuel cells offer a promising alternative as they combine high energy density with fast refueling, as it is further mentioned. To meet the high demands and challenging conditions in heavy transport, innovative material combinations and the latest laser technology are being used. Temperature fluctuations, mechanical stresses, and corrosive environments strain the relevant materials and the processing of the individual components. This requires skill.

Modular fuel cell stacks for transport logistics

The project builds on this approach. It favors a combination of a metallic carrier foil with a conductive compound foil to combine the advantages of both types. The large-format hybrid compound bipolar plates are good electrical conductors, mechanically stable, and have excellent corrosion resistance—all properties that are crucial for heavy transport. These plates are intended to extend the lifespan of fuel cells while simultaneously lowering production costs. In addition, the modular structure of the fuel cell stacks allows for scaling to different application areas, spanning commercial vehicles to ships and even stationary applications.

This is what's happening in this research project:

The metallic carrier foil is produced by the project coordinator Thyssenkrupp Steel with a chromium layer to improve corrosion resistance and bonding properties to the compound foil. Fraunhofer UMSICHT specifically controls the electrical and thermal conductivity of the compound foil, achieved through the selection of specific materials and fine-tuning their composition. Fraunhofer ILT is dedicated to further developing laser-based technology for the production and functionalization of the hybrid compound bipolar plates. Joining techniques are also being investigated there. Research focuses on selective stripping of the compound elements using laser radiation and the final electrochemical characterization of the hybrid stack. Experts use various laser techniques to introduce microstructures into the components to improve the connection between the metallic and polymer-based components. Everything also needs to be hydrogen-tight, of course. In addition, ILT is developing processes for the removal of material layers to maximize the electrical conductivity of the bipolar plates.