Electrochemical Characterisation of Vacuum Plasma Sprayed SOFCs on Different Porous Metallic Substrates

Metallic substrate supported thin-film SOFCs have been in development at DLR Stuttgart for nearly ten years. In the DLR SOFC concept, the entire cell is fabricated using an integrated multi-step vacuum plasma spray (VPS) process. The material and structure of the porous metallic substrates play an important role for the electrochemical performance of the sprayed cells. Therefore the paper concentrates on the investigation of different porous substrates, e.g. felts, foams and knitted wire structures, and on the electrochemical behaviour of the cells. The plasma sprayed cells with a size of 10 cm x 10 cm were characterised electrochemically by current-voltage measurements, impedance spectroscopy and by investigating their long term stability. In order to analyse possible degradation mechanisms, the cells were examined metallographically after operation. The different phases and elements were detected with the energy dispersive X-ray microanalysis (EDX) associated with the scanning electron microscope and the X-ray diffraction (XRD).