Properties and electrochemical performance of Sr0.8La0.2TiO3-δ-Ce0.8Gd0.2O2-δ composite anodes for intermediate temperature solid oxide fuel cells

A series of Sr0.8La0.2TiO3-delta (SLT)-Ce0.8Gd0.2O2-delta (GDC) composite anodes with various volume ratios of SLT and GDC has been synthesized using a sucrose modified combustion technique. The percolation thresholds of Sr0.8La0.2TiO3-delta and Ce0.8Gd0.2O2-delta in the composite calculated based on the Kusy's percolation theory were 75.6 vol.% and 36.1 vol.%, respectively. While the rate of carbon deposition increased with an increase in the Ce0.8Gd0.2O2-delta content, the total electrical conductivity decreased in humidified H-2 as well as in CH4. Based on the electrochemical performance measured using AC-impedance spectroscopy, the optimal anode composition was 65 vol.% Sr0.8La0.2TiO3-delta-35 vol.% Ce0.8Gd0.2O2-delta. This composite has polarization resistances of 2.80 Omega cm(2) and 4.60 Omega cm(2) in H-2 and CH4, respectively, measured at 800 degrees C. Diffusion or concentration polarization was the rate determining steps for the fuel oxidation process in the Sr0.8La0.2TiO3-delta-Ce0.8Gd0.2O2-delta composite anode. (C) 2015 Elsevier B.V. All rights reserved.