NdBaCu2O5+delta and NdBa0.5Sr0.5Cu2O5+delta layered perovskite oxides as cathode materials for IT-SOFCs

摘要

Cobalt-free perovsldte oxides NdBaCu2O5+delta (NBCO) and NdB(a)0(.5)Sr(0.5)Cu(2)O(5+delta) (NBSCO) has been investigated as cathode materials in intermediate-temperature solid fuel cells (IT-SOFCs). The crystal structure, thermal expansion, electrical conductivity and electrochemical properties have been characterized by X-ray diffraction (XRD), dilatometer, four-probe dc method, electrochemical impedance spectroscopy (EIS) and cathodic polarization examinations. The average thermal expansion coefficients (TEC) values of NBCO and NBSCO are 13.0 x 10(-6)/degrees C and 14.5 x 10(-6)/degrees C, which are more desirable on combining with the electrolytes than cobalt-based cathodes. The partly substitution of Sr on B-site increases the electron hole concentration and improves the conductivity. The polarization resistances values of NBSCO are 0.205 Omega cm(2), 0.200 Omega cm(2) and 0.135 Omega cm(2), whereas the polarization resistances values of NBCO are 8.61 Omega cm(2), 3.18 Omega cm(2) and 0.83 Omega cm(2) at 600 degrees C, 700 degrees C and 800 degrees C, respectively. The improved electrochemical performance of NBSCO should be ascribed to the higher conductivity as well as the improved oxygen adsorption/desorption and oxygen ions diffusion processes. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.