Ceria (La3+, Sr2+)/Carbonates Nanocomposite Electrolytes with High Electrical Conductivity for Low-Temperature SOFCs

Abstract

A series of ceria-based nanocomposites consisting of lanthanum and strontium codoped ceria with composition Ce0.89La0.07Sr0.04O1.925 (CL7S4) and eutectic mixture of carbonates Li2CO3-Na2CO3 (LNCO) have been prepared by mixing nanosize powders of CL7S4 and LNCO. Samples have been characterized using differential thermal analysis, X-ray diffraction, scanning electron microscopy combined with energy-dispersive spectroscopy, thermal expansion, and impedance spectroscopy. A sharp increase in ionic conductivity is observed in all the composite specimens corresponding to superionic transition. Sample containing 35 wt% of carbonate shows the maximum conductivity (2.56 × 10-1 S/cm at 500°C) with activation energy of conduction, Ea 0.23 eV. © 2014 The American Ceramic Society.