The project investigated the influence of laser structuring and nanoparticle‑based surface treatments on the wettability and electrical contact resistance of bipolar plates (BPP) intended for use in polymer electrolyte membrane fuel cells. Contact‑angle measurements on laser‑structured samples revealed only minor changes after coating. Uncoated specimens exhibited angles between 85.5° and 90°, while coated samples ranged from 90° to 102°. The RAU sample showed a slight hydrophilic tendency after structuring, which disappeared once the coating was applied, indicating that the laser pattern alone does not significantly alter wettability. To achieve a pronounced hydrophilic or hydrophobic surface, the team applied aqueous nanoparticle solutions. Reference plates treated with a hydrophilic formulation reached contact angles of 30°, whereas the hydrophobic formulation produced angles of 87°, and these effects remained stable after 24 h immersion at 80 °C.

Electrical performance was evaluated by measuring the inter‑contact resistance (ICR). Untreated plates had an ICR of 0.1 mΩ cm², whereas coated plates without nanoparticle additives showed values of 4.2 mΩ cm² and 6.85 mΩ cm², a substantial increase. When nanoparticle suspensions were mixed with the coating solution, only the hydrophilic mixtures (ratios C and D) yielded acceptable coatings. Sample C achieved an ICR of 0.42 mΩ cm², and sample D reached 0.14 mΩ cm², close to the standard coating performance. Hydrophobic mixtures, however, produced ICRs of 6.8 mΩ cm², attributed to island formation and disrupted cross‑linking within the coating matrix. After 24 h soaking, the ICR of the hydrophilic samples rose to 3.7 mΩ cm² and 2.2 mΩ cm², while the hydrophobic samples increased dramatically to 28.6 mΩ cm², confirming that the coating integrity deteriorates under aqueous exposure.

Long‑term immersion tests were conducted at 0.9 V and 0.6 V in both a standard electrolyte and a DOE‑designed electrolyte. In the standard electrolyte, the ICR increased from 3.7 mΩ cm² after 500 h to 35.2 mΩ cm² after 1500 h, following an exponential trend. In contrast, the DOE electrolyte showed a much slower rise, reaching only 6.1 mΩ cm² after 1500 h, indicating a saturation effect and reduced corrosion. At 0.6 V, the ICR remained below 3.5 mΩ cm² for all durations, demonstrating that lower potentials mitigate degradation. These results highlight the critical role of electrolyte composition in preserving electrical performance over time.

Laser cutting experiments established the relationship between laser power, focus position, and achievable cutting speed. With a 500 W laser at a 0.1 mm material thickness, a safe speed of 75 m/min was attainable; increasing power to 1 kW and 1.5 kW raised speeds to 150 m/min and 200 m/min, respectively. Shifting the focus by 0.5 mm reduced the maximum safe speed by 5 m/min, underscoring the sensitivity of the process to optical alignment. These findings inform the design of roll‑to‑roll manufacturing lines for BPP.

Quality assurance involved surface‑energy measurements using calibrated test inks to detect contamination introduced during laser processing. The study identified optimal laser parameters that minimize melt‑droplet adhesion and preserve surface cleanliness, thereby ensuring reliable coating adhesion.

The project ran from January 2020 to June 2023 and was coordinated by the Institute for Process Technology (IPT). Precors GmbH supplied coated sheet materials and provided expertise in nanoparticle formulations. The Forschungszentrum Jülich (FZJ) conducted the wettability, electrical, and corrosion tests, as well as the laser‑cutting trials. The consortium also included other partners responsible for process integration and data management. While the final demonstration of a fully functional fuel‑cell stack using the roll‑to‑roll produced plates was not achieved within the project timeframe, the results identify clear pathways for redesigning the plate geometry, refining sealing concepts, and developing new manifold designs that combine cutting, welding, and sealing technologies. The project’s findings are made available to all partners through an online platform, facilitating knowledge transfer and supporting future technology deployment.