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 La 0.8Sr 0.2Ga 0.8Mg 0.2O 3-δ (LSGM) electrolyte. Various cathode materials La 0.6Sr 0.4Co 0.2Fe 0.8O 3-δ (LSCF), Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3-δ (BSCF), and Pr 0.3Sr 0.7Co 0.8Fe 0.2O 3-δ (PSCF) were compounded with La 0.8Sr 0.2Ga 0.8Mg 0.1Co 0.1O 3-δ (LSGMC) as a mixed conducting composite element. All powders were synthesized by the glycine-nitrate process (GNP). XRD analysis found resistive phases of LaSrGaO 4 and LaSrGa 3O 7 present in the calcined layer of composite cathodes on LSGM. A bulk ohmie resistance of 3.81 Ω·cm and an interfacial resistance value of 0.16 Ω were measured for LSCF/LSGMC composite cathode on LSGM substrate at 800°C in air. Low-frequency secondary ares 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 800°C (0.11 A/cm at 0.045 V overpotential) while the BSCF/LSGMC performed best at the lowest temperature investigated (0.1 A/cm at 700°C and 0.04 V overpotential). ©The Electrochemical Society.