Effect of NiO addition on oxygen reduction reaction at lanthanum strontium cobalt ferrite cathode for solid oxide fuel cell

Lanthanum strontium cobalt ferrite (LSCF), a perovskite's family member, has gained much attention as the electrocatalyst for the oxygen reduction reaction (ORR) in intermediate temperature solid oxide fuel cells. However, it still needs a strategy to improve its catalytic activity. In this work, NiO is primarily investigated as a possible synergistic catalyst for ORR on the LSCF surface. The effect of NiO particles on the effective oxygen chemical surface exchange coefficient is revealed with the electrical conductivity relaxation (ECR) technique. At 800 °C, the coefficient is increased from 3.48 × 10−5 to 6.65 × 10−5 cm s−1 and 6.9 × 10−4 cm s−1 when NiO particles are deposited using the sputter and drop coating methods, respectively. Adding 5 wt % NiO to LSCF reduces the area specific interfacial polarization resistance, for example from 0.108 to 0.082 Ω cm2 at 700 °C, as demonstrated by impedance spectroscopy on symmetric cells using samaria-doped ceria as the electrolyte. Adding NiO can also improve the performance of anode supported button cells, increasing the peak power density from 0.731 to 1.031 W cm−2 at 800 °C. On the whole, the increased oxygen surface exchange rate together with the reduced electrode resistance and improved power density, exhibit that NiO is a potential additive to enhance the LSCF catalytic activity.