H2 Giga_PEP.IN: Designing the PEM electrolysis of tomorrow

"PEP.IN" is part of the hydrogen lead project H₂ Giga of the Federal Ministry of Education and Research (BMBF). The abbreviation stands for industrialization of PEM electrolysis production. In other words, the project partners are optimizing processes and devices in order to mass-produce electrolysers and electrolysis stacks. This work includes research into a production facility for electrolysis stacks and electrolysers as well as the consistent further development of electrolysis stacks to make them as simple and cost-effective as possible to produce.

Against this background, Fraunhofer UMSICHT is developing a new type of stack design for PEM electrolysis based on composite bipolar foils from its own calendering process in the "PEP.IN" sub-project "Design of Tomorrow". The stack design is to be manufactured exclusively from thermoplastic cell components (bipolar foils, frame elements, membrane electrode unit) and using conventional joining processes (laser or ultrasonic welding). This means that hundreds of sealing surfaces in the electrolysis stack can be replaced by robust weld seams. Sub-goals are the qualification of the thermoplastic bipolar foil for use in PEM electrolysis, the development of thermoplastic-joinable membrane electrode units and a stack design, which is to be demonstrated as a short stack.

The market ramp-up for electrolysers for the production of green hydrogen is anchored in the German government's National Hydrogen Strategy and stipulates an expansion of hydrogen capacity of 10 gigawatts by 2030. To achieve these goals, H₂ Giga aims to identify and test innovative processes for the competitive and series production of electrolysers in Germany in order to make green hydrogen affordable and competitive.

In contrast to the state of the art, the stack concept developed by Fraunhofer UMSICHT in "Design of Tomorrow" promises high material efficiency through the use of alternative, polymeric materials for bipolar foils as well as fundamentally rethought cell and stack concepts based on materially bonded components. In contrast to bipolar foils made of titanium, for example, the bipolar foils offer electrical conductivity through the use of a highly filled composite made of carbon and thermoplastic, while at the same time being manufactured cost-effectively and continuously using the powder-to-roll calendering process. Additionally, the bonding of the bipolar foil, frame elements, and membrane electrode units can replace any seals in the electrolysis cell. This drastically reduces the number of components in the cell, which in turn reduces the number of stacking processes and thus the assembly effort. In addition, the joining process eliminates vulnerable sealing surfaces and replaces them with robust weld seams, which contributes significantly to a reduction in production waste.

• A membrane laminate that can be joined with thermoplastics has been developed.
• The cell concept was successfully demonstrated on a laboratory scale in a short stack with a total cell area of approx. 100 cm²
• The long-term operation of the carbon-based bipolar foil was demonstrated in accelerated stress tests over 500 hours without any carbon corrosion being observed.

• MAN Energy Solutions SE (Coordination)
• H-TEC Systems GmbH
• AUDI AG
• VAF GmbH
• Fraunhofer ISE
• Fraunhofer IPA
• Zentrum für Brennstoffzellentechnik GmbH
• Forschungszentrum Jülich GmbH