Effect of porous interlayer on the long-term stability of (La0.8Sr0.2)0.97MnO3 cathode for solid oxide fuel cells

In this work, the effect of porous interlayer on the microstructural change of LSM cathodes and yttria-stabilized zirconia (YSZ) electrolyte was investigated under a current-accelerated condition at 1000 °C. The polarization resistance of LSM cathode on bare yttria-stabilized zirconia (YSZ) electrolyte decreased significantly after discharge at 1.2 A cm−2 for 5 h, and then started to increase gradually. However, when a porous YSZ interlayer was employed between LSM cathode and YSZ electrolyte, the polarization resistance did not increased even after discharge at the same condition for 40 h. The performance changes of the two kinds of cathodes were related with the microstructural change of the interface between LSM cathode and YSZ interlayer. Quantitative analysis for the microstructural change of LSM cathode on YSZ interlayer revealed that even after discharge at 1.2 A cm−2 for 40 h, 90% of the triple phase boundary of LSM, YSZ and gas phase remained active for oxygen reduction reaction. On the other hand, the LSM cathode on YSZ electrolyte with a porous Sm-doped ceria interlayer showed remarkable long-term stability even after discharge at 1.2 A cm−2 for 160 h.

► Long-term stability of LSM cathode was improved by using a porous interlayer.
► The microstructure of the cathode–interlayer interface was quantitatively evaluated.
► Active TPB length ratio of the LSM cathode was preserved by using porous interlayer.
► LSM cathode with an SDC interlayer showed remarkable long-term stability.
► Nanosized Ce-rich particles were observed on the grain boundary LSM cathode.