Layered Perovskite GdBaCuCoO5+δ Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cells

Layered perovskite oxide GdBaCuCoO5+delta (GBCC) was investigated as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The GBCC cathode was chemically compatible with the electrolytes La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) and Sm0.2Ce0.8O1.9 (SDC) at temperatures below 950 degrees C. Compared with LaBaCuCoO5+delta (LBCC) cathode, the electrical conductivity behaviors of GBCC and LBCC were quite distinct from each other in the studied temperature range due to the different electronic configurations of the rare-earth cations. The GBCC sample exhibited a semiconductor-like behavior. For the LBCC sample, however, there was a transition of the electrical conductivity behavior from semiconductor-like to metal-like for temperatures higher than 475 degrees C. The thermal expansion coefficient of samples significantly decreased from 18.3x10(-6) K-1 for LBCC to 15.1x10(-6) K-1 for GBCC in the temperature range of 30-850 degrees C, although the area specific resistance (ASR) increased. The ASRs of the GBCC cathode on the LSGM and SDC electrolytes were 0.091 and 0.129 cm(2) at 750 degrees C, respectively. At 800 degrees C, the power densities of a single cell were 545 and 528 mW cm(-2) for the LSGM and SDC electrolytes, respectively, making it a promising candidate as a cathode material for IT-SOFCs.