Nano-ceria pre-infiltration improves La0.6Sr0.4Co0.8Fe0.2O3−x infiltrated Solid Oxide Fuel Cell cathode performance

Abstract

Here, scanning electron microscopy, X-ray diffraction, and thermo-gravimetric analysis experiments show that the pre-infiltration of Ce0.9Gd0.1O1.95 (GDC) nano-particles reduces the average size of La0.6Sr0.4Co0.8Fe0.2O3−x (LSCF) produced from the subsequent infiltration of precursor nitrate solutions containing the surfactant Triton X-100 or the chelating agent citric acid. In contrast, GDC pre-infiltration has no effect on the average size of LSCF particles produced from precursor solutions containing only lanthanum, strontium, cobalt, and iron nitrate. Consistent with the observed particle size trends, electrochemical impedance spectroscopy measurements show that GDC pre-infiltration improves the performance of Triton X-100 Derived (TXD) LSCF–GDC cathodes and Citric Acid Derived (CAD) LSCF–GDC cathodes, but has no effect on the performance of Pure Nitrate Derived (PND) LSCF–GDC cathodes. In particular, TXD LSCF–GDC cathodes with more than ∼5 vol% of GDC pre-infiltration display average LSCF particle sizes of 21 nm and open-circuit polarization resistance values of 0.10 Ωcm2 at 540 °C, compared to 48 nm and 640 °C without GDC pre-infiltration. Results suggest that this 100 °C reduction in cathode operating temperature is caused solely by LSCF particle size reductions. 7.4 vol% GDC pre-infiltrated TXD LSCF–GDC cathodes also display lower 540 °C degradation rates than conventionally infiltrated PND LSCF–GDC cathodes.