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

A method 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.