Preparation and Performance of Cathode Materials Ba_(1-x)Sr_xCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ) for Intermediate-temperature Solid Oxide Fuel Cells

The Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ(x=0, 0.1, 0.2, 0.3, 0.4) oxides were synthesized by the conventional solid state reaction process and investigated as a cathode for intermediate temperature solid oxide fuel cells(IT-SOFCs). All prepared Ba1-x Srx Co0.7Fe0.2Nb0.1O3-δ(x=0-0.4) powders were sintered at 1000 ℃. X-ray diffraction patterns indicate that all samples have a single phase of cubic perovskite structure. The morphologies of the symmetric cell were characterized by a scanning electron microscope(SEM). The cathode exhibits fine uniform microstructure with appropriate porosity, and shows good bonding and continuous contact with the dense Ce0.85Sm0.15O1.925(SDC) electrolyte pellet. AC impedance spectra based on SDC electrolyte measured at intermediate temperatures show that a cathode Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δexhibits the best electrochemical performance. The maximum power density of single cell with Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δcathode, Ni0.9Cu0.1-SDC anode and SDC electrolyte is 155 mW/cm2at 600 ℃.The encouraging results suggest that Ba0.8Sr0.2Co0.7Fe0.2Nb0.1O3-δis a very promising cathode material for IT-SOFCs.