Understanding thermal and redox cycling behaviors of flat-tube solid oxide fuel cells

The performance stability of solid oxide fuel cells (SOFCs) under thermal and redox cycles is vital for large-scale applications. In this work, we investigated the effects of thermal and redox cycles on cell performances of flat-tube Ni/yttria-stabilized zirconia (Ni/YSZ) anode-supported SOFCs. Cell performance was considerably affected by the duration of oxidation during redox cycles and the heating rate during the thermal cycles. The cell tolerated 20 short-term redox cycles (5 min oxidation) without significant performance degradation. Besides, the cell exhibited superior stability during 8 thermal cycles with a slow heating rate (4 °C min⁻¹) to that with a fast heating rate (8 °C min⁻¹). These results reflected that the thick anode support (2.7 mm) offered strong resistance to the shocks caused by redox and thermal cycling. Moreover, the morphological changes of the Ni phase during the redox and thermal cycling were investigated using Ni-film anode cells. Agglomeration of Ni particles and dissociation between the Ni film and the YSZ substrate were confirmed after 5 redox cycles, whereas no significant changes in Ni film emerged after 8 thermal cycles.