Electrochemical evaluation of La0.6Sr0.4Co0.8Fe0.2O3−δ–La0.9Sr0.1Ga0.8Mg0.2O3−δ composite cathodes for La0.9Sr0.1Ga0.8Mg0.2O3−δ electrolyte SOFCs

The composite cathodes consisting of perosvkite material La0.6Sr0.4Co0.8Fe0.2O3−δ (LSCF) and La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM) were prepared, and then studied for potential applications in intermediate temperature solid oxide fuel cells (SOFCs) with LSGM electrolyte. Both ac impedance spectroscopy and dc polarization measurements were performed in air within the temperature range of 600–800 °C under open circuit potential. The results showed that the addition of 40 wt% LSGM to LSCF (LSCF–LSGM40) resulted in lower interfacial resistance (0.24 Ω cm2 at 800 °C) than other composite cathodes and was slightly lower than the single-phase LSCF cathode (0.28 Ω cm2 at 800 °C). Although adding LSGM electrolyte material to the LSCF electrode did not improve the electrode performance much, it could buffer the thermal expansion coefficient (TEC) of LSCF, which is larger than that of LSGM electrolyte.