Percolation effect on electrical, mechanical, and electrochemical properties of Sr_0.8La_0.2TiO₃–Ce_0.9Gd_0.1O_1.95 composite anodes for solid oxide fuel cells

Both the electrical conductivity and mechanical strength of a Sr_0.8La_0.2TiO₃–Ce_0.9Gd_0.1O_1.95 (SLT-GDC) composite decreased non-linearly as the GDC content increased. In the GDC percolation region, the electrical conductivity and the mechanical strength decreased significantly. Because the carbon deposition rate increased with increasing GDC content, the redox stability decreased. The area specific resistance (ASR) of the SLT-GDC composite anode at 800 °C in H₂ decreased up to 15 vol.% GDC (SLT-GDC15) and then increased at the SLT-GDC20 and the SLT-GDC33 compositions, due to the high electro–catalytic activity and low electrical conductivity of GDC. Consequently, the SLT-GDC15 composition within the mixed region below SLT and GDC percolation limit exhibited the best electrochemical performance due to the optimized electronic and ionic conduction network. - Highlights: • SLT-GDC composite anodes can be designed by percolation theory. • Incorporation of GDC improves catalytic activity. • Composite within SLT percolation threshold exhibits high mechanical strength. • Composite within the mixed percolation region exhibits the best catalytic activity. • Redox stability of the SLT-GDC composite is correlated with GDC volume.