Two processes for the production of bipolar plates

Bipolar plates are central components of fuel cell and electrolyzer stacks. In the "H2Go" research project, researchers at Fraunhofer IPT are developing two production methods for manufacturing bipolar plates: discrete and continuous stamping. The discrete forming process is still state-of-the-art in industrial production today. The design of the bipolar plate is transferred into a thin stainless steel sheet on both sides. The result is a kind of half plate that is joined to a bipolar plate in several process steps, depending on the intended use of the subsequent stack.
Continuous embossing using the roll-to-roll process (R2R) is a production technology of the future that scientists at Fraunhofer IPT are testing. In roll-to-roll embossing, a metal foil is guided over a roller system and processed in a continuous process. The design of the biopolar plate is transferred to a metal foil by structured rollers. In the next step, a laser cuts out the half plate and welds two pieces together to form a bipolar plate. The second, optimized R2R system is currently being set up and tested in the "H2Go" research project.

Flexible system technology for continuous production

The future system technology should be flexibly expandable. The scientists at Fraunhofer IPT have, therefore, developed the modular machine concept "Scalab": A basic architecture serves as the starting point for the machine design, which can be supplemented with various modules and expanded into a production line. Different manufacturing processes for metal or plastic foils can be linked together in this way.

In the "CoBiP" research project, the research team has integrated the continuous manufacturing process in a system prototype for the production of bipolar plates. The special feature of this production system is its modular design: It allows the production line to be individually designed and expanded by replacing or adding functional units. As the development cycles of most products are becoming ever shorter, the flexible system architecture offers a number of advantages, as production can be converted to new variants and product designs particularly quickly. The processing technologies that can be used in an R2R system are diverse and range from coating technologies and pick-and-place assembly processes to laser cutting and welding processes.

The MEA: central component of the electrolyzer and fuel cell

For hydrogen production, not only can bipolar plates be manufactured continuously using the R2R process, but MEAs can as well. The classic production of MEAs consists of four steps: coating, drying, assembling and cutting. These steps can also be mapped in the Scalab system. In the "H2GIGA - FRHY" project, a Fraunhofer research team is continuing to develop the flexible system design in order to apply the catalyst layer directly to the membrane on both sides. Inkjet and near-infrared technologies are being tested for this.

With the "Reference Factory.H2," Fraunhofer IPT, together with the Fraunhofer Institute for Machine Tools and Forming Technology IWU and the Fraunhofer Institute for Electronic Nano Systems ENAS, is forming a value-creation community that is driving forward the rapid ramp-up of efficient, unit-scalable production technologies. Together with industrial companies, the three research institutes are developing solutions for cost-effective hydrogen systems in mass production.

Storing hydrogen safely in pressurized tanks

After the production of hydrogen, the storage of the gaseous energy carrier also plays an important role: Pressure tanks produced for this purpose must be highly resilient and durable. For years, scientists have been researching suitable concepts for pressure tank production that meet the high safety standards required. To produce the high-strength hydrogen tanks, Fraunhofer IPT uses a winding process in which thermoplastic fiber-reinforced tape is wrapped around a plastic base body and welded by laser heating. Stress tests have shown that tanks manufactured using this process can withstand an operating pressure of up to 700 bar. Laser-assisted winding has proven to be advantageous because thermoplastic fiber composites can be processed well, no post-consolidation is necessary and the material can be recycled.

The Fraunhofer Institute for Production Technology IPT combines many years of knowledge and experience in all areas of production technology. In the fields of process technology, production machinery, production quality and metrology as well as technology management, Fraunhofer IPT offers its customers and project partners applied research and development for networked, adaptive production. The institute's range of services is geared towards the individual tasks and challenges within specific industries, technologies and product areas, including     automotive engineering and suppliers, energy, life sciences, aviation, mechanical and plant engineering, optics, precision and microtechnology as well as tool and mold making.

Together with other Fraunhofer Institutes, Fraunhofer IPT will be exhibiting the technologies for hydrogen production and storage at the Hannover Messe in Hall 13, Stand C47.