Influence of Working Parameters on Anode-Supported Cells studied by Electrochemical Impedance Spectroscopy

Electrochemical Impedance Spectroscopy (EIS) is one of the most common techniques to characterize Solid Oxide Fuel Cells (SOFCs) during operation and to evaluate the influence on their performances of several working conditions and degradation effects. However the processes overlap in the frequency domain makes difficult to clearly distinguish each cell contribution and to understand the impedance spectra. This becomes even more challenging when complete SOFCs are under investigation. In this work a state of the art anode-supported cell has been characterized by means of current-voltage curves and EIS under several working conditions. A preliminary investigation consisting in varying the electrodes gases compositions and flows allowed to identify the corresponding processes on the impedance spectra. Afterward, the evolution of such contributions has been studied at the Open Circuit Voltage (OCV) varying the cell working temperature in the range 700-800°C and applying electrical loads up to 1 Acm-2. Post- experiment analyses have been carried out to support the electrochemical observations.