Extensive analysis of large planar SOFC: Operation with humidified methane and carbon monoxide to examine carbon deposition based degradation

Feeding the cells with CH4/H2O/N2 mixtures results in better performance than when using CO/H2O/N2 mixtures, but also induces rapid cell degradation. Methane cracking effects a carbon coverage of the Ni catalyst and ion conducting YSZ surfaces, and increases the polarization resistance. Temperature measurements indicate preferred steam reforming activity at the gas inlet region. Stable cell voltage is achieved after slight initial degradation when fueling with CO/H2O/N2 mixtures. Carbon depositions are observed only on the surface of the anode, in the supply pipes, cell housing and the contact mesh.