Redox-cycling studies of anode-supported microtubular solid oxide fuel cells

Abstract

Accidental reoxidation is one of the most critical issues of SOFC anodes, leading to performance degradation or even producing catastrophic failure of the cell. In this work several redox cycling experiments over microtubular SOFC cells are reported. Oxidation kinetic parameters have been determined for this geometry by Thermogravimetric Analysis (TGA). Oxidation kinetics is known to be diffusion limited at typical operation conditions and, for this reason, strictly dependant on geometry. A linear relationship was found between expansion kinetics and damage on SOFC anodes in a series of dilatometric experiments for the same temperature. A microtubular Ni-YSZ/YSZ/LSM-YSZ cell was also redox cycled several times at partial oxidation conditions (22% oxidation) and performance degradation was measured by j-V characterization and the loss was found to be approximately 2% in performance per cycle.