Optimization and design for additive manufacturing of a fuel cell end plate

Proton exchange membrane fuel cells (PEMFCs) represent today one of the most common types of fuel cells for mobility applications due to their comparatively high-power density, low operating temperature, and low costs. A PEMFC regularly consists of a stack of individual cells in which each consists of polar plates and a membrane electrode assembly. To achieve the best possible electric conductivity over the series connection of cells, the contact pressure in between the cells must be uniformly distributed over the cell area. This pressure is usually applied to the stack by end plates, which frame the stack and are clamped together by bolts, which are tightened by a defined torque. Typically, these end plates are made from bulk material with no or limited optimization. Looking at mobility applications, e.g., in aerospace, a fuel cell should ideally provide high efficiency at the lowest weight. Based on this assumption, this paper uses topology optimization varying the material as well as the design space to derive new design concepts for the end plates of a PEMFC. The designs are compared with respect to an even stress distribution to the fuel cell stack, the weight of the plates, and the manufacturability in the laser powder bed fusion process. The most promising design is manufactured and results in a weight decrease of 48% compared to previously used aluminum bulk plates. Finally, the optimized base plates are applied to a test cell and the performance is compared to their conventional counterparts, showing a 1% increase in electric stack power despite the lower mass.