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Journal of power sources 578, 233242 (2023). doi:10.1016/j.jpowsour.2023.233242, Published by Elsevier, New York, NY [u.a.]

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022; Aachen : RWTH Aachen University 1 Online-Ressource : Illustrationen, Diagramme (2023). = Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2022, During the assembly of polymer electrolyte membrane electrolysis cells and polymer electrolyte membrane electrolysis stacks, thin layer components are pressed together by endplates and clamping elements such as screws. The mechanical assembly is crucial for the functionality of the installed components. For example, the electrical contact, which is crucial for the electrochemical production of hydrogen, and the sealing of an electrolyzer depend to on the contact pressure between the individual components.In this work, the mechanical behaviour of electrolysis cells and electrolysis stacks was investigated via experimental methods and simulated using a new type of static-mechanical model. Using these methods, it was possible to investigate the influence of the contact pressure, the sealing materials, sealing geometries, and the endplate design on the mechanical behaviour of the layer structures of an electrolyzer. Increasing the contact pressure on the active cell area increases the electrical performance on the one hand but increases the hydrogen crossover on the other hand. This work found an optimum average contact pressure of 1.23 MPa for a meander flowfield structure at a theoretical compression of the carbon paper of 30%. Furthermore, a uniform contact pressure distribution was found to be advantageous. The contact pressure distribution can be additionally homogenized by design measures such as stiff, porous materials or alternative flowfield structures such as an expanded metal. For the selection of a suitable sealing material as well as the suitable sealing geometry, it could be derived that the tightness can be increased by an increase of the assembly forces, the reduction of the sealing surface as well as a compressible and also mechanically stable sealing material. A mechanically sufficient endplate concept can achieve a uniform pressure distribution since endplates are the central element for the force introduction into the cell. A new concept of an adjustable end plate was developed to dynamically compensate for endplate bending and the associated uneven contact pressure distribution throughout the electrolysis stack. Based on this endplate concept and the findings from the investigations on the mechanical behaviour of electrolysis cells and electrolysis stacks, a mechanically optimized PEM electrolysis stack was derived and realized as a prototype. Finally, this novel stack design with an active cell area of 100 cm² was successfully tested experimentally regarding its mechanical functionality., Published by RWTH Aachen University, Aachen