Degradation of a High Performance SOFC Cathode by Cr-Poisoning at OCV-Conditions

作者：Kornely M^*; Menzler N H; Weber A; Ivers Tiffee E

来源：Fuel Cells, 2013, 13(4): 506-510.

DOI：10.1002/fuce.201200182

• Anode-Supported Cell
• Cathode
• Cr-Poisoning
• Degradation
• DRT
• EIS
• Metallic Interconnector (MIC)
• SOFC

In this work we investigate the effect of Cr-poisoning at OCV-condition by means of electrochemical impedance spectroscopy (EIS). The anode-supported cell (ASC) is operated in Cr-free environment for the first 70h of the cell test at 800 degrees C supplying air to the cathode and a varying mixture of H2O/H-2 to the anode. The performance of the cell is determined by current-voltage (CV) measurement after the start up. After an operating time of 70h in the absence of chromium species a Cr-source was switched on by passing the oxidant (air) through a Crofer22APU powder bed. In order to determine the degradation caused by Cr-poisoning electrical impedance spectra are collected at every 29h of operating time. After further 275h at OCV-condition in the presence of Cr-source another CV-curve is measured. A detailed analysis of the measured impedance spectra by the distribution of relaxation times (DRT) enables a separation of the cathode polarization resistance. During the Cr-free operation the cathode polarization shows a constant value. After the Cr-source is switched on a strong increase of the cathode polarization resistance is observed. This unique result shows clearly that Cr-poisoning of an LSM/8YSZ-cathode already takes place at OCV-condition.

• 出版日期2013-8