Preparation and characterization of Nd2-xSrxCoO4+δ cathodes for intermediate-temperature solid oxide fuel cell

K2NiF4-type structural Nd2-xSrxCoO4+delta (x = 0.8, 1.0, 1.2) was synthesized and evaluated as cathodes for intermediate-temperature solid oxide fuel cell (IT-SOFC). The crystal structure, thermal expansion, electrical conductivity and electrochemical properties were investigated by X-ray diffraction, dilatometry, DC four-probe method, AC impedance and polarization techniques. It is found that the electrochemical properties were remarkably improved with the increasing of Sr in the experiment range. Nd0.8Sr1.2CoO4+delta showed the highest electrical conductivity of 212 S cm(-1) at 800 degrees C, the lowest polarization resistance and cathodic overpotential, 0.40 Omega cm(2) at 700 degrees C and 35.6 mV at a current density of 0.1 A cm(-2) at 700 degrees C, respectively. The chemical compatibility experiment revealed that Nd0.8Sr1.2CoO4+delta cathode was chemically stable with the SDC electrolyte. The thermal expansion coefficient also increased with the Sr content. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.