Spatially Resolved Analysis of the Influence of Three-Dimensional Flow Field Structures on Loss Processes in PEMFCs

This study introduces a novel measurement device and technique to spatially resolve the influence of 3D flow field structures consisting of extended metal meshes on the performance distribution in PEMFCs. The newly designed segmented cell enables not only the measurement of the current distribution but also local electrochemical impedance spectra, subsequently analyzed by the distribution of relaxation times. The 3D flow field structures provide, despite of an increased HFR, an advantage at high current densities. The spatially resolved DRT analysis enabled the identification of polarization processes revealing that the gas diffusion process is greatly reduced compared to a conventional channel-rib design. In particular, the 3D coarse mesh shows promising advantages for application under high current densities. The findings from this study provide valuable insights into the local power and resistance distribution, enabling optimization of the flow field design and improvement of the performance of fuel cells with large active areas.