Electrical properties and sulfur tolerance of La0.75Sr0.25Cr1−xMnxO3 under anodic conditions

Complex metal oxides with composition of La0.75Sr0.25Cr1−xMnxO3(x=0.4,0.5,0.6)(x=0.4,0.5,0.6) (LSCM) have been synthesized and examined as anode materials for solid oxide fuel cells (SOFCs). LSCM compositions show excellent tolerance to both reduction and oxidation but the crystal structure transforms from hexagonal in air to orthorhombic in H2. The volume change associated with this phase transformation is only about 1%, thus having little effect on other properties. The total electrical conductivity increases with the content of Mn, whereas the resistance to sulfur poisoning increases with the content of Cr. Fuel cells using LSCM as the anode show very good performance when pure hydrogen is used as the fuel. However, they do not appear to be stable in fuels containing 10% of H2S.

Fuel cell performance with La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM55) as anode at different temperatures. The fuel gas was humidified hydrogen (3% H2O vapor) at a flow rate of 20 ml/min and the cathode was exposed to stationary air.Figure optionsDownload as PowerPoint slide