As potential intermediate-temperature SOFC cathodes, perovskite
composite cathode materials were evaluated in combination with a
La0.8Sr0.2Ga0.8Mg0.2O3-δ (LSGM) electrolyte. Various cathode
materials La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), Ba0.5Sr0.5Co0.8Fe0.2O3-δ
(BSCF), and Pr0.3Sr0.7Co0.8Fe0.2O3-δ (PSCF) were compounded
with La0.8Sr0.2Ga0.8Mg0.1Co0.1O3-δ (LSGMC) as a mixed
conducting composite element. All powders were synthesized by
the glycine-nitrate process (GNP). XRD analysis found resistive
phases of LaSrGaO4 and LaSrGa3O7 present in the calcined layer
of composite cathodes on LSGM. A bulk ohmic resistance of 3.81
Ω·cm2 and an interfacial resistance value of 0.16 Ω were measured
for LSCF/LSGMC composite cathode on LSGM substrate at
800ºC in air. Low-frequency secondary arcs in the impedance
spectra of LSCF/LSGMC cathode coupled with low current
density and low cathode porosity suggested possible mass transfer
limitations. The LSCF/LSGMC composite electrode performed
best at 800ºC (0.11 A/cm2 at 0.045 V overpotential) while the
BSCF/LSGMC performed best at the lowest temperature
investigated (0.1 A/cm2 at 700ºC and 0.04 V overpotential).