La0.8Sr1.2CoO4+δ–CGO composite as cathode on La0.9Sr0.1Ga0.8Mg0.2O3−δ electrolyte for intermediate temperature solid oxide fuel cells

Abstract

La0.8Sr1.2CoO4+δ (LSCO4) material with K2NiF4-type structure has been synthesized via a citric–nitrate process and characterized. Composite materials La0.8Sr1.2CoO4+δ-Ce0.9Gd0.1O2−δ (CGO) (LSCO4–CGO) have been prepared and evaluated as cathode for intermediate temperature SOFC (IT-SOFC) based on La0.9Sr0.1Ga0.8Mg0.2O3−δ (LSGM) electrolytes. LSCO4 oxide is chemically compatible with CGO and LSGM electrolyte at temperature up to 1000 °C. Compared with the pure LSCO4, the optimum composition of LSCO4–35 wt % CGO exhibits better electrochemical activity for oxygen reduction. Also, for LSCO4–35 wt % CGO electrode, SEM results suggest that better microstructure is obtained and the electrode forms good contact with the electrolyte after sintering at 1000 °C for 2 h. At 750 °C, the polarization resistance of the LSCO4–35 wt % CGO composite cathode is about 0.21 Ω cm2 in air. A cell with a 1.2 mm thick LSGM electrolyte, NiO as anode, and LSCO4-35 wt % CGO as cathode displays a maximum power density of 515 mW cm−2 at 750 °C. These results indicate that LSCO4–CGO composite materials are promising cathode candidates for intermediate-temperature solid oxide fuel cells with LSGM electrolyte.