Conductivity, catalytic property and electrochemical performance of a new perovskite-type SOFC anode material

A perovskite related material, La0.75Sr0.25Cr0.5Fe0.5O3-delta (LSCF), has been synthesised and examined as a potential anode material for solid oxide fuel cells (SOFC). The material exhibits an overall orthorombic structure with a = 5.4926 +/- 0.0005 Angstrom, b = 5.5339 +/- 0.0004 Angstrom, c = 7.7646 +/- 0.0008 Angstrom. V = 236.01 +/- 0.05 Angstrom(3) according to the X-ray data. It is chemically stable under SOFC anode conditions. The conductivity of LSCF at 900degreesC is 14.3 and 0.21 S/cm respectively in air and 5% H-2. An 11% methane conversion was observed at 900degreesC when the steam to methane ratio is 1:1. A methane conversion of 68% with CO2-selectivity of 99% is achieved at 900degreesC when equal molar of CH4 and O-2 were introduced into the reactor. The anode polarisation resistance in wet 5% H-2/Ar and wet H-2 are about 1.79 Omegacm(2) and 1.15 Omegacm(2) respectively at 850degreesC. A fuel cell with a maximum current density of 640 mA/cm(2) was achieved in wet H-2 at 900degreesC. LSCF itself is not an ideal SOFC anode material although it is redox stable in reducing atmosphere at high temperatures and exhibits good catalytic effects for methane-reforming.