Electrochemical Investigation of LSGMC-Composite Cathodes on LSGM-Substrate

Abstract

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).