La_0.8Sr_1.2CoO_4+δ-CGO composite as cathode on La_0.9Sr_0.1Ga_0.8Mg _0.2O_3-δ electrolyte for intermediate temperature solid oxide fuel cells

La_0.8Sr_1.2CoO_4+δ (LSCO4) material with K₂NiF₄-type structure has been synthesized via a citric-nitrate process and characterized. Composite materials La _0.8Sr_1.2CoO_4+δ-Ce_0.9Gd _0.1O_2-δ (CGO) (LSCO4-CGO) have been prepared and evaluated as cathode for intermediate temperature SOFC (IT-SOFC) based on La_0.9Sr_0.1Ga_0.8Mg_0.2O _3-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.