Investigation of 2R-Cell Degradation under Thermal Cycling and RedOx Cycling Conditions by Electrochemical Impedance Spectroscopy

A 2R-cell with a 10 cm2 active area LSCF cathode on a CGO buffer layer was tested at 780°C under thermal and RedOx cycling conditions; 20 thermal cycles were performed between 780°C and 100°C, using 200°C/h heating ramps and natural cooling, followed by 20 RedOx cycles, during which air was fed to the anode for 1 hour at 780°C, causing the cell potential to drop to zero. V-i polarisation curves and electrochemical impedance spectroscopy (EIS) measurements were performed before and after each consecutive cycle in order to monitor the performance losses. The OCV remained stable during the whole test whereas the area specific resistance (ASR) measured at 0.5 A/cm2 increased by +1.3 mΩcm2 per thermal cycle and by +1.8 mΩcm2 per RedOx cycle. The cell was examined after the test by scanning electron microscopy (SEM).