Development of solid oxide fuel cells based on a Ce(Gd)O2-x electrolyte film for intermediate temperature operation

Initial tests have been carried out with the fuel cell arrangement La0.6Sr0.4Co0.2Fe0.8O3 parallel to Ce(0.9)Gd(0.1)O(1.95)parallel to Ni/YSZ, incorporating dense film (5-10 mu m) Ce0.9Gd0.1O1.95 electrolyte tape cast onto the supporting anode, to investigate the feasibility of intermediate temperature operation (500-700 degrees C). A good open circuit voltage of approx. 0.8 V was obtained at 550 degrees C using moist hydrogen as the fuel. Slightly lower open circuit voltages were found at higher temperatures, which may have been caused by minor gas leakage and the electronic conductivity of the electrolyte. Power outputs in excess of 100 mW/cm(2) were obtained at 650 degrees C, and the cell resistance was 0.8 Omega cm(2) at this temperature. This resistance, and the greater resistance at lower temperature, was predominantly due to the cathode according to AC impedance measurements. Experiments were also carried out at 600 degrees C using direct methanol fuels at the anode; the maximum power output was approximately half of that obtained with hydrogen. (C) 1997 Elsevier Science B.V.