Chemical Compatibility and Electrical Contact of LaNi_(0.6)Co_(0.4)O_(3-δ) (LNC) between Crofer22APU Interconnect and La_(0.6)Sr_(0.4)FeO_3 (LSF) Cathode for IT-SOFC

摘要

In order to simulate the contact situation of interconnect/contact layer/cathode in SOFC stacks, contact resistance and chemical compatibility of LaNi_(0.6)Co_(0.4)O_(3-δ) (LNC) as contact layer between Crofer22APU interconnect and La_(0.6)Sr_(0.4)FeO_3 (LSF) cathode was investigated at 800℃ in air for more than 1300 h using X-ray diffraction (XRD), scanning electron microscopy (SEM) set-up equipped with an energy dispersive X-ray analyser (EDX) and area specific resistance (ASR) measurements. The XRD analysis reveals that multiple phases were formed during ASR test. The point microanalysis on cross-section of Fe-Cr/LNC/LSF system, after ASR measurements, shows chromium within the porous contact material mainly concentrated close to interconnect, but no Cr, Ni, or Co was detected in the cathode. It was found between LNC and LSF cathode, a thin and uniform layer which contains Sr, La, Cr, Co, Ni, and Fe. The contact between layers could act as a physical barrier for element migration and thus can suppress degradation of the cathode for these systems. The area specific resistance slope depends on the interactions between the contact material and/or cathode and the interconnect. Co-containing spinels formed during ASR test can be responsible of the resistance decrease of the system, related to the low degradation of the cell.