Durability Testing of a Short SOFC Stack under Direct Internal Steam Reforming of Methane

One 5-cell SOFC stack has been tested under both hydrogen and direct internal steam reforming of methane for a total duration of 3200 hours. Electrochemical impedance spectroscopy has been used to monitor the evolution of internal resistances of all repeating units in the stack. It has been found that repeating units in the stack degraded two times faster under direct internal steam reforming of methane (6.7 - 14.4%/kh voltage degradation) than under H-2 (2.3 - 4.0%/kh). In combination with impedance results, this indicates deterioration of the anode as the main cause of degradation for operation under CH4/H2O. The degradation process is at least partially reversible when changing the gas from CH4 to H-2.