In-situ Electrochemical Characterization of SOFC cell Degradation: The Cases of Mechanical Damage and Carbon Deposition

Abstract

A methodology has been proposed to analyze the electrochemical degradation of the ASC configuration. This methodology, based on the measurement of the cell response by impedance spectroscopy, has been applied to study the cell performances degradation, (i) when the anode is re-oxidized under an ionic current, and (ii) upon direct methane reforming. In the first case, a thin cermet layer growing from the anode/electrolyte interface has been oxidized and then reduced. This 'redox' cycle has been repeated until the complete degradation of the cell. It has been found that the impedance diagram's evolution is consistent with a delamination between the ACC/AFL interface. In the second case, the cell has been operated under methane conditions known to favour the coking. The analysis of the impedance diagrams has shown a degradation of the current collection. This result has been found to be consistent with the location of carbon deposit inside the cell.

SOFC Running on Biogas: Identification and Experimental Validation of "Safe" Operating Conditions

“…This study, detailed in (36) and presented in (39), has allowed separating cathode contribution from the rest of the EIS diagram. A "reference" cathode fit has been defined on the basis of all the cathode contribution recorded and fitted on every samples tested in this study under hydrogen and air (it had been assumed that cathode answer would be similar when the anode was fed with hydrogen or with CH 4 /CO 2 gas mixture).…”