Ag-Perovskite Composite Materials for SOFC Cathode-Interconnect Contact

Silver-perovskite composites with the perovskite being either (La(0.6)Sr(0.4))(Co(0.8)Fe(0.2))O(3) (LSCF) or La(0.8)Sr(0.2)MnO(3) (LSM) were evaluated as the contact material between the ferritic interconnect alloy Crofer 22 APU and the LSM cathode. The area-specific resistances (ASRs) of the test specimens were highly dependent on the volume percentage and the type of the perovskite present in the composite contact material as well as the amount of thermal cycling that the specimens were subjected to during testing. The chromium content present in both the contact layer and the adjacent cathode material was measured after testing, and the Ag-LSCF composite contact materials proved more effective in trapping Cr within the contact material and preventing Cr migration into the cathode than the Ag-LSM composites. Silver-perovskite composite contact materials are promising candidates for use in intermediate-temperature solid oxide fuel cell (SOFC) stacks with ferritic stainless steel interconnects due to their ability to maintain acceptably low ASRs while reducing Cr migration into the cathode material.