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

Abstract

Abstract 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 Sr 0.5 Ba 1.5 CoMoO 6 − δ anode material exhibits Fm -3 m symmetry with B-site rock salt-type cation ordering, while YBaCo 2 O 5 + δ cathode material possesses P 4/ mmm space group with A-site layered-type cation ordering. In the case of SmBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5 + δ compound, partial (> 70 wt.%) A-site layer-type ordering was observed. Electrical conductivity σ of Sr 0.5 Ba 1.5 CoMoO 6 − δ anode material is much lower ( − 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 Sr 0.5 Ba 1.5 CoMoO 6 − δ is significantly enhanced (~ 0.5 S·cm − 1 ). Chemical stability studies at 1000 °C revealed that YBaCo 2 O 5 + δ reacts with Ce 0.8 Gd 0.2 O 1.9 , while SmBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5 + δ remains stable. In the case of Sr 0.5 Ba 1.5 CoMoO 6 − δ compound, long time annealing in reducing atmosphere of 5 vol.% H 2 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 H 2 | Sr 0.5 Ba 1.5 CoMoO 6 − δ | Ce 0.8 Gd 0.2 O 1.9 | SmBa 0.5 Sr 0.5 Co 1.5 Fe 0.5 O 5 + δ IT-SOFCs was recorded.