SmBa_(0.5)Sr_(0.5)Cu_2O_(5+δ) and SmBa_(0.5_Sr_(0.5_GuFeO_(5+δ) layered perovskite oxides as cathodes for IT-SOFCs

摘要

Novel Cobalt-free layered perovskite oxides SmBa_(0.5)Sr_(0.5)Cu_2O_(5+δ) (SBSCO) and SmBa_(0.5)Sr_(0.5)Cu_2O_(5+δ) (SBSCFO) were investigated as cathode materials for intermediate-temperature solid fuel cells (IT-SOFCs). The thermal expansion coefficients (TEC) of SBSCO and SBSCFO were 14.1 × 10~(-6)/℃ and 14.9 × 10~(-6)/℃ in 50 ℃-800 ℃, which were more compatible with electrolyte than cobalt-based cathodes. When A'-site is partially substituted by Sr, the conductivity of SBSCO and SBSCFO had been improved. The max electrical conductivity of SBSCO was 277.7 S cm~(-1), about one order of magnitude higher than SmBaCu_2O_(5+δ). Polarization resistance of SBSCO is 0.25 Ω cm~2 at 650 ℃, which is twice lower than that of SmBaCu_2O_(5+δ) (SBCO). This implies SBSCO has higher activity for oxygen reduction than SBCO. Preliminary results indicate that SBSCO are promising as cathodes for IT-SOFCs.