• Dahl, Vedrana Andersen
• Simonsen, Søren Bredmose
• Alfaro, Silvia M.
• Steenberg, Thomas
• Bentzen, Janet Jonna
• Hjuler, Hans Aage
• Bodner, Merit

Abstract

In high temperature polymer electrolyte fuel cells, polybenzimidazolemembranes doped in phosphoric acid are used as electrolytematerial. The membrane thickness directly relate tothe amount of absorbed acid which relate to performance. In this study,we compare scanning electron microscopy and X-raymicro-computed tomography (CT) regarding suitability for determining thestructure of electrolyte membranes. Semi-automatedlayer identification and thickness estimation was used to reduce humanerrors and data processing time. Scanning electronmicroscopy was found reliable for membrane thickness characterizationdespitenecessary destructive sample preparation. WithX-ray CT it was possible to study the cells non-destructively before andaftercell test. This made it possible to identify,so-called hot pressing, as the step in which the membrane lost most ofits thickness.After cell operation, the use of X-ray CT at largefield of view and a recently developed layer detection algorithm made itpossible to visualize compression of the membranein a pattern identical to that of the flow plate channels. Thiscompressionpattern would have been difficult to determine withconventional electron microscopy or X-ray CT without semi-automatedlayerdetection.

Topics

• polymer
• scanning electron microscopy
• tomography
• hot pressing