Synthesis and characterization of Sr0.75Y0.25Co0.9Ru0.1O3-δ perovskite as a solid oxide fuel cell cathode material

The oxygen-deficient Sr0.75Y0.25Co0.9Ru0.1O3-delta (SYCR) cathode is systematically evaluated for the application of solid oxide fuel cells. X-ray diffraction analysis indicates that SYCR presents a tetragonal structure with space group of I4/mmm (139). In the measured high oxygen partial pressure (pO(2)) region (0.01-0.21 atm), the conductivity increases with increasing pO(2) because of the oxygen vacancy annihilation and hole creation, relating to a general p-type semiconducting mechanism. To get an insight into the rate-limiting step of SYCR cathode, behaviors of individual polarization resistance (R-1 and R-2) are investigated in different pO(2). The obtained fitting results reveal that R-1 is nearly independent on the pO(2), while R-2 presents a (pO(2))(-0.5) dependence. At 800 degrees C, SYCR cathode exhibits an R-p value of 0.14 Omega cm(2), moreover, when using the wet hydrogen (similar to 3% H2O) as fuel and ambient air as oxidant, the maximum power density of single cell Ni-YSZ (yttria-stabilized zirconia)|YSZ|SYCR reaches 452.9 W cm(-2).