High Performance Infiltrated Backbones for Cathode-Supported SOFC's

The concept of using highly ionic conducting backbones with subsequent infiltration of electronically conducting particles has widely been used to develop alternative anode-supported SOFC´s. In this work, the idea was to develop infiltrated backbones as an alternative design based on cathode-supported SOFC. The cathodes are obtained by infiltrating LSM into a sintered either thick (300 μm) yttria stabilized zirconia (YSZ) backbone or a thin YSZ backbone (10-15 μm) integrated onto a thick (300 μm) porous strontium substituted lanthanum manganite (LSM) and YSZ composite.

Fabrication challenges, microstructural characterization and electrochemical testing are discussed. Data on polarization resistance, R_p, are obtained from impedance spectra recorded on quasi-symmetrical cells (YSZ backbones/YSZ/LSM-YSZ (screen printed)). The backbones are infiltrated with LSM and compared to a standard LSM-YSZ screen printed symmetrical cells. Samples with LSM/YSZ composite  and YSZ backbones made with graphite+PMMA as pore formers exhibited comparable R_p values to the  screen printed LSM/YSZ cathode. This route was chosen as the best to fabricate the cathode supported cells.

SEM micrograph of a cathode supported cell with infiltrated LSM nanoparticles is shown in Fig. 1.

Figure 1. Cross section of LSM infiltrated cathode supported cell.