Nd_(0.5)Sr_(0.5)Fe_(0.8)Cu_(0.2)O_(3-δ)-xSm_(0.2)Ce_(0.8)O_(1.9) cobalt-free composite cathodes for intermediate temperature solid oxide fuel cells

摘要

Cobalt-free composites Nd_(0.5)Sr_(0.5)Fe_(0.8)Cu_(0.2)O_(3-δ) (NSFCu)-xSm_(0.2)Ce_(0.8)O_(1.5) (SDC) (x = 0-60 wt %) are investigated as IT-SOFC cathodes. The characteristic properties of cobalt-free composite cathodes comparing to cobalt-based composites are revealed. The DC conductivity and thermal expansion coefficient of the composite cathodes decrease with the content of SDC x, while the polarization resistance R_p shows the least value with addition of 40 wt% of SDC. The power density of the single cell with NSFCu-40% SDC composite cathode improved significantly compared with that of undoped NSFCu cathode, with peak values of 488, 623, 849 and 1052 mW cm~(-2) at 600, 650, 700, and 750 ℃, respectively. Moreover, the performance of the composite cathode is stable within testing period of 370 h at 700 ℃, indicating that the NSFCu-40% SDC is an excellent cobalt-free composite cathode applied in IT-SOFC.