Ni-Fe alloy-supported intermediate temperature SOFCs using LaGaO₃ electrolyte film for quick startup

Intermediate temperature solid oxide fuel cells (SOFCs), which are highly tolerant against a thermal cycle, are studied by using the Ni-Fe porous alloy substrate prepared by an in situ reduction. It was found that Ni-Fe alloy exhibits high activity against anodic reaction and suitable compatibility with LaGaO₃ electrolyte. The electrolyte film of La_0.9 Sr_0.1 Ga_0.8 Mg_0.2O₃ (LSGM) and Sm_0.2 Ce_0.8O₂ (SDC) bilayer with 5 μm thickness was successfully prepared on the dense NiO-Fe₂O₃ composite anode. After a in situ reduction, the dense plate of NiO-Fe₂O₃ was changed to the porous Ni-Fe alloy substrate; however, the LSGM film can keep the dense state. The prepared Ni-Fe alloy that supported LSGM cell demonstrated the maximum power densities of 0.9 W/cm² and 0.4 W/cm² at 873 K and 573 K. After heating up to 873 K within 540 s, there is no crack formed on the film and almost the theoretical open circuit voltage was exhibited. In addition, the maximum power density of 400 mW/ cm² was achieved at 773 K. After the thermal cycling, the decrease in the maximum power density was not large, and this suggests that the film is still gas tight and highly tolerant against the thermal cycle. Quick start characteristics of the metal support SOFC could expand the SOFC application to the electric source of a mobile-field-like automobile.