BiFoilStack—Novel Cell and Stack Design with Compound-Foil-Based Bipolar Plates for Heavy-Duty Fuel Cell Systems

Within this publication the project »BiFoilStack« is presented, aiming to develop novel stack concepts for heavy duty applications using graphite-polymer composite bipolar foil-based plates. The stack requirements are derived from current long-haul applications, considering the latest efforts in standardization of fuel cell systems, and considering the targets set by the European Clean Hydrogen Partnership as well as the US Department of Energy. Overall target is the increase of durability and power density of the stack. This will be realized through the careful formulation of the graphite-polymer compound foil, used as material for the BPP, and the design of the cells. A design approach is shown to define and pre-optimize the high-level specifications of the fuel cell—cell aspect ratio, port areas, flow field concept, and channel design. Furthermore, the design is targeted to enable high current density operation, facilitating water removal and cooling. Additionally, the production process of the bipolar foil is shown including a characterization of the fundamental mechanical properties. First reshaping investigations, with a within the project developed reference flow field, proved excellent formability of the used material for the target size of the involved structures. Next steps are the wholistic characterization of the material properties and continuous optimization of the material formulation. Furthermore, the design of the flow field will be computationally optimized, and the MEA specified. The project will be concluded with the electrochemical characterization of short stacks on dedicated test benches to confirm the achievement of the set targets.