Porous nickel-iron alloys as anode support for intermediate temperature solid oxide fuel cells: II. Cell performance and stability

Abstract

Porous nickel–iron alloy supported solid oxide fuel cells (SOFCs) are fabricated through cost-effective ceramic process including tape casting, screen printing and co-sintering. The cell performance is characterized with humidified hydrogen as the fuel and flowing air as the oxidant. Effects of iron content on the cell performance and stability under redox and thermal cycle are investigated from the point of view of structural stability. Single cells supported by nickel and nickel–iron alloy (50 wt % iron) present relatively high discharge performance, and the maximum power density measured at 800 °C is 1.52 and 1.30 W cm−2 respectively. Nickel supported SOFC shows better thermal stability between 200 and 750 °C due to its dimensional stable substrate under thermal cycles. Posttest analysis shows that a dense iron oxide layer formed on the surface of the nickel-iron alloy during the early stage of oxidation, which prevents the further oxidation of the substrate as well as the functional anode layer, and thus, making nickel-iron supported SOFC exhibits better redox stability at 750 °C. Adding 0.5 wt % magnesium oxide into the nickel-iron alloy (50 wt% iron) can inhibit the metal sintering and reduce the linear shrinkage, making the single cell exhibit promising thermal stability.