Influence of local carbon fibre orientation on the water transport in the gas diffusion layer of polymer electrolyte membrane fuel cells

We used synchrotron X-ray imaging to investigate the influence of local fibre structures of gas diffusion layers (GDLs) in polymer electrolyte membrane fuel cells on the transport of water. Two different measurement techniques, namely in-situ radiography and ex-situ tomography, were combined to reveal the structure-properties relationships between the three-dimensional fibre arrangement and the water flow. We found that the orientation of the local carbon fibres strongly affects the direction of liquid water transport. The carbon fibres act as guiding rails for the water droplets. These findings provide completely new ideas on how gas diffusion media in various types of fuel cells could be designed, in order to optimise transport pathways for liquid water and therefore increase cell performance.