Evaluation of Nd SrCa CoO ( = 0, 0.05, 0.1, 0.15, 0.2) as a cathode material for intermediate-temperature solid oxide fuel cells.

A series of Nd SrCa CoO ( = 0, 0.05, 0.1, 0.15, 0.2) cathode materials was synthesized by sol-gel method. The effect of Ca doping amount on the structure was examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal expansion, and X-ray photoelectron spectroscopy (XPS). Electrochemical properties were evaluated for possible application in solid oxide fuel cell (SOFC) cathodes. Results showed that second phase NdCaCoO is generated when the Ca doping amount is higher than 0.1. The increase in Ca limits the electronic compensation capacity of the material, resulting in a decrease in thermal expansion coefficient (TEC). With the increase of Ca content, the conductivity increases at first and then decreases, and the highest value of 443 S cm is at = 0.1 and = 800 °C. NdSrCaCoO exhibits the lowest area specific resistance of 0.0976 Ω cm at 800 °C. The maximum power density of NdSrCaCoO at 800 °C is 409.31 mW cm. The Ca-doped material maintains good electrochemical properties under the coefficient of thermal expansion (CTE) reduction and thus can be used as an intermediate-temperature SOFC (IT-SOFC) cathode.