On-Line In-Situ Diagnostics of Processes Within PEM Fuel Cells by Raman Spectroscopy

This contribution intends to show how Raman spectroscopy can be used to pursue processes inside PEM fuel cells. For this, two experimental setups have been worked out. At first a microscope objective was inserted into one bipolar plate. This enabled the detection of hydrogen, oxygen, nitrogen, vaporous and liquid water as well as changes in gas compositions and water distribution induced by an artificial pinhole within the MEA. A multiple-fiber Raman spectrometer with seven twin fibers was then developed to refine the look inside fuel cells. This setup permits the simultaneous record of gas compositions, liquid water and water vapor and how those species do change locally during operation. Beside the collection of data for modelling fuel cell processes, the multiple-fiber setup is primarily considered to monitor degradation processes and pre-stages of membrane damages.