Evaluation of a Single Cell and Candidate Materials with High Water Content Hydrogen in a Generic Solid Oxide Fuel Cell Stack Test Fixture, Part II: Materials and Interface Characterization

摘要

A generic solid oxide fuel cell (SOFC) test fixture was developed to evaluate candidate materials under realistic operating conditions. A commercial 50 mm x 50 mm NiO-YSZ anode-supported thin YSZ electrolyte cell with lanthanum strontium manganite (LSM)/YSZ cathode was tested to evaluate the stability of candidate materials. The cell was tested in two stages at 800℃: stage I with low (～3% H_2O) humidity and stage II with high (～30% H_2O) humidity hydrogen fuel in constant voltage or constant current mode. Part I of the work, published previously, provided information regarding the generic test fixture design, materials, cell performance, and optical post-mortem analysis. In part II, detailed microstructure and interfacial characterizations are reported regarding the SOFC candidate materials: (Mn,Co)-spinel conductive coating, alumina coating for sealing area, ferritic stainless steel interconnect, refractory sealing glass, and their interactions with each other. Overall, the (Mn,Co)-spinel coating was very effective in minimizing Cr migration. No Cr was identified in the cathode after 1720 h at 800℃. Aluminization of metallic interconnects also proved to be chemically compatible with alkaline-earth silicate sealing glass. The details of interfacial reaction and microstructure development are discussed.