Electrical performance of nano-structured La_0.6Sr_0.4Co_0.2Fe_0.8O_3-δ impregnated onto yttria-stabilized zirconia backbone

Perovskite structure La_0.6Sr_0.4Co_0.2Fe_0.8O₃−δ (LSCF) nano-particles are deposited onto porous yttria-stabilized zirconia frameworks via an ion impregnation/infiltration process. The apparent conductivity of the impregnated LSCF nano-structure is investigated regarding the fabricating parameters including LSCF loading, heat-treatment temperature, heating rate, and annealing at 750^◦C for 400 hr. The conductivity and the intrinsic conductivity of the impregnated LSCF is estimated from the apparent conductivity using the conductive model for the impregnated network. The conductivity increases with LSCF loading while the interfacial polarization resistance exhibits the lowest value at an optimal loading of about 5 vol.%, which corresponds to the largest three-phase boundary as predicted using the numerical infiltration methodology. At the optimal loading, the area specific ohmic resistance of the impregnated LSCF is about 0.027 cm² at 700^◦C for a typical impregnated cathode of 30 μm thick. It is about 20% of the cathode interfacial polarization resistance and 3.5% of the total resistance for a single cell consisting of a Ni-YSZ support, a 10 μm thick electrolyte and a 30 μm thick cathode.