Electrochemical performance evaluation of FeCo₂O₄ spinel composite cathode for solid oxide fuel cells

In this work, we report FeCo₂O₄-xCe_0.8Sm_0.2O_1.9 (x = 0, 30, 40, 50, 60, 70 wt%), catalyst/electrolyte composite oxides, as cathode materials for application in solid oxide fuel cells. Herein a systematic investigation represents the effect of Ce_0.8Sm_0.2O_1.9 incorporation on physical and electrochemical properties. The obtained results indicate that the addition of Ce_0.8Sm_0.2O_1.9 to form FeCo₂O₄–Ce_0.8Sm_0.2O_1.9 composite material plays a key role in physical and electrochemical properties. Among all the components, the FeCo₂O₄–60Ce_0.8Sm_0.2O_1.9 composite cathode has the lowest polarization resistance of ∼0.094 Ω cm² at 800 °C in air, which is much smaller than that of the FeCo₂O₄ cathode (4.18 Ω cm²). In comparison with the FeCo₂O₄ cathode, the FeCo₂O₄–60Ce_0.8Sm_0.2O_1.9 composite cathode has a better electrocatalytic activity and a larger power density of 397 mWcm⁻² based an electrolyte-supported single-cell configuration at 800 °C. The oxygen partial pressure dependence studies indicate that rate limiting steps of the FeCo₂O₄–60Ce_0.8Sm_0.2O_1.9 composite cathode are the adsorption process of the molecular oxygen on the electrode surface and the charge-transfer process. In consequence of these superior properties, it is reasonable to believe that the FeCo₂O₄–60Ce_0.8Sm_0.2O_1.9 oxide has great potential to become a cathode material for solid oxide fuel cells.