Improving Oxygen Electrodes by Infiltration and Surface Decoration

For improving competitiveness of SOEC/SOFC-technology it is desirable to reduce the temperature of operation down towards 500 °C - 600 °C. This requires improvement of the oxygen electrode such that this does not limit performance. Here, we report results on modifying various back-bone type oxygen electrodes via infiltration of materials targeting a surface decoration with Pr-oxide or Pr,Ni,Cu-oxides. Different composite back-bone electrodes (based on micron-sized particles) were investigated; La0.6Sr0.4Co0.2Fe0.8O3/Ce0.9Gd0.1O2, (LSCF/CGO), La0.6Sr0.4FeO3 (LSF), and LaNi0.6Fe0.4O3/Ce0.9Gd0.1O2 (LNF/CGO). Marked performance improvements could be achieved with the infiltration, including a reduction by a factor of 3 of the polarization resistance at 600 °C for both LSF and the LSCF/CGO based state of the art electrodes. In a LNF/CGO composite backbone, infiltration with Pr-nitrate led to marked electrode performance improvement; reaching 0.14 Ωcm2 at 550 °C and 0.4 Ωcm2 at 500 °C, sufficiently fast not to limit overall cell performance (at 550 °C).