Application of In-Situ Diagnostic Methods for the Study of SOFC Operational Behaviour

Kurzfassung

In order to optimise the operational behaviour of fuel cells and minimise cell degradation it is very helpful to use in-situ and ex-situ analytical methods. The application of advanced diagnostic methods by monitoring cell characteristics under real operating conditions provides valuable information to be used for the development of degradation mitigation strategies. The application of these methods in SOFC development is significantly limited mainly due to the experimental problems that are associated with the high operating temperature. However, an increasing effort in developing and implementing non-traditional analytical methods such as spatially resolved measurements and imaging techniques for SOFC development has been made in recent years. The presentation gives an overview of in-situ diagnostic methods that are applied at DLR Stuttgart for the study of SOFCs. It includes spatially resolved measurements with an experimental segmented cell configuration where different techniques such as IV characteristics, impedance spectroscopy, gas chromatography and temperature measurement are involved. The investigation by means of segmented cells aims at the determination of local effects and the identification of critical operating conditions during technically relevant SOFC operation. Recently, a new test setup with transparent optical access has been built up allowing for microscopic observation of processes within the cell as well as for application of in-situ laser Raman spectroscopy to determine highly resolved concentrations of gas species along a flow channel. Examples of analytical studies by applying these diagnostic methods are presented and potentials and limitations of the different techniques are discussed.