Cation-ordered perovskite-type anode and cathode materials for solid oxide fuel cells

In this work selected cation-ordered perovskite-type anode and cathode materials were investigated in terms of their possible application in intermediate temperature solid oxide fuel cells (IT-SOFC). Their phase composition, oxygen content, chemical diffusion coefficient of oxygen D and surface exchange coefficient K, chemical stability in relation to ceria electrolyte, and stability of the anode material in reducing atmosphere were studied. It was found that Sr0.5Ba1.5CoMoO6 − δ anode material exhibits Fm-3m symmetry with B-site rock salt-type cation ordering, while YBaCo2O5 + δ cathode material possesses P4/mmm space group with A-site layered-type cation ordering. In the case of SmBa0.5Sr0.5Co1.5Fe0.5O5 + δ compound, partial (> 70 wt.%) A-site layer-type ordering was observed. Electrical conductivity σ of Sr0.5Ba1.5CoMoO6 − δ anode material is much lower (< 0.1 S·cm− 1), as compared to the studied cathode materials, for which σ > 100 S·cm− 1 in 600-800 °C temperature range was measured. However, in reducing conditions, conductivity of Sr0.5Ba1.5CoMoO6 − δ is significantly enhanced (~ 0.5 S·cm− 1). Chemical stability studies at 1000 °C revealed that YBaCo2O5 + δ reacts with Ce0.8Gd0.2O1.9, while SmBa0.5Sr0.5Co1.5Fe0.5O5 + δ remains stable. In the case of Sr0.5Ba1.5CoMoO6 − δ compound, long time annealing in reducing atmosphere of 5 vol.% H2 in Ar at 800 °C caused decomposition of the material. Despite poor stability of the anode material in reducing conditions, relatively good performance of constructed H2 | Sr0.5Ba1.5CoMoO6 − δ | Ce0.8Gd0.2O1.9 | SmBa0.5Sr0.5Co1.5Fe0.5O5 + δ IT-SOFCs was recorded.