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−δ (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 (pO2) region (0.01–0.21 atm), the conductivity increases with increasing pO2 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 (R1 and R2) are investigated in different pO2. The obtained fitting results reveal that R1 is nearly independent on the pO2, while R2 presents a (pO2)−0.5 dependence. At 800 °C, SYCR cathode exhibits an Rp value of 0.14 Ω cm2, moreover, when using the wet hydrogen (∼ 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.