Manganese-doped lanthanum calcium titanate as an interconnect for flat-tubular solid oxide fuel cells

Abstract

A cost-effective screen-printing process is developed to fabricate a dense layer of solid oxide fuel cell (SOFC) interconnect material. A series of lanthanum-manganese-doped CaTiO3 perovskite oxides (La0.4Ca0.6Ti1-xMnxO3-delta; (x = 0.0, 0.2, 0.4, 0.6)) powders is successfully synthesized using an EDTA-citrate method and co-sintered as an interconnect material on an extruded porous anode substrate in a flat-tubular solid oxide fuel cell. All samples adopt a single perovskite phase after calcination at 950 degrees C for 5 h. High-temperature XRD confirms that the perovskite structure is thermally stable in both oxidizing and reducing conditions. The highest electrical conductivity occurs when x = 0.6; at 12.20 S cm(-1) and 2.70 S cm(-1) under oxidizing and reducing conditions. The thermal expansion coefficient of La0.4Ca0.6Ti1-xMnxO3-delta is 10.76 x 10(-6) K-1, which closely matches that of 8 mol% yttria-stabilized zirconia. Chemical compatibility of samples and their reduction stability are verified at the operating temperature. The power density and area-specific resistance value at x = 0.6 is 208 mW cm(-1) and 1.23 Omega cm(2) at 800 degrees C under open circuit voltage, and 200 mV signal amplitude under 3% humidified hydrogen and air respectively. This performance indicates that La0.4Ca0.6Ti1-xMnxO3-delta has potential for use as interconnect in a flat tubular SOFC. (C) 2013 Elsevier B.V. All rights reserved.