Characteristics of SrCo1-xSnxO3-δ cathode materials for use in solid oxide fuel cells

In this study, introduction of tin ions in the SrCoO3-delta oxide is attempted to modify its electrochemical behavior for serving as a cathode of intermediate-temperature solid oxide fuel cells (IT-SOFCs). Doping of tin ions appears to stabilize the cubic Pm-3m phase of the SrCo1-ySnyO3-delta ceramics but generates SrSnO3 precipitates and inhibits the grain growth as y value rises to a level greater than 10%. Obtained at 550 degrees C, the maximum electrical conductivity of SrCo0.95Sn0.05O3-delta reads 545 S cm(-1). Single cells with a structure of NiO-Sm0.2Ce0.8O2-delta (SDC)/SDC/SrCo0.95Sn0.05O3-delta-SDC are built and characterized. Though SrCo0.95Sn0.05O3-delta is regarded as an MIEC (mixed ionic/electronic conductivity material), adding SDC to SrCo0.95Sn0.05O3-delta guarantees good adhesion to and fine electrical contact with the electrolyte layer, thereby contributing to the reduction in R-0 and R-p values. The single cell with the SrCo0.95Sn0.05O3-delta-SDC composite cathode at 700 degrees C registers respectively an R-0 value of 0.044 Omega cm(2) and an R-P value of 0.109 Omega cm(2). In the absence of microstructure optimization and hermetic sealing of cells, a high power density of 0.847 W cm(-2) is reached. SrCo1-ySnyO3-delta thus emerges to be a promising cathode material for IT-SOFCs applications. (C) 2012 Elsevier B.V. All rights reserved.