Optimization of La0.2Sr0.7-xCaxTi0.95Fe0.05O3-delta Fuel Electrode Stoichiometry for Solid Oxide Fuel-Cell Application


Development of active ceramic hydrogen electrodes with high stability is an important challenge for developing solid oxide fuel cells (SOFC). Herein, a set of cubic perovskite-type La/Ca/Fe-doped strontium titanates, La0.2Sr0.7-xCaxTi0.95Fe0.05O3-delta (LSCTF), was synthesized. Their crystallographic and electrical properties, catalytic activity, and stability, as well as performance as fuel electrodes in the solid oxide fuel cell (SOFC) have been evaluated. It was confirmed by the results that the LSCTF behave like semiconductors, and the conductivity, catalytic activity, and stability of the electrodes significantly depend on the Ca concentration in the A-site. In the case of an optimal composition of the La0.2Sr0.35Ca0.35Ti0.95Fe0.05O3-delta fuel electrode, a polarization resistance value of 0.21 Omega cm(2) at 850 degrees C in a humidified (1.7% H2O) H-2 atmosphere was obtained. During the stability test, the fuel cell with the 50 wt % La0.2Sr0.35Ca0.35Ti0.95Fe0.05O3-delta + 50 wt % Ce0.9Gd0.1O2-delta anode showed a power density of 322 mW cm(-2) at 850 degrees C in a 98.3% H-2 + 1.7% H2O atmosphere.