Synthesis and characterization of terbium doped barium cerates as a proton conducting SOFC electrolyte

A novel proton conductor, BaCe0.95Tb0.05O3-a (BCTb) perovskite was synthesized via the EDTA-citrate acid complexing method, followed by high temperature calcination. The properties of the powders were characterized by thermo gravimetric-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), Scanning electron microscopy (SEM) and the conductivity measurement using the 4-probe method. In order to obtain the pure perovskite structure, the calcination temperature was elevated at 1000 degrees C or greater. The electrical conductivities of the BCTb perovskite mainly result from protons and are 6.51 x 10(-3) -2.0 x 10(-2) S cm(-1) in the temperature range of 600-850 degrees C with the activation energy of 41.95 kJ mol(-1). A Ni-BCTb vertical bar BCTb vertical bar LSCF(La0.6Sr0.4Co0.2Fe0.8O3-alpha)-BCTb fuel cell was subsequently fabricated via a co-pressing/co-sintering method, followed by slurry-coating of the cathode. With 50 mL min(-1) pure hydrogen as fuel and the ambient air as oxidant, the maximum output of the fuel cell has reached to 753 mW cm(-2) at 700 degrees C. The results demonstrate that BCTb perovskite may be a promising electrolyte for the proton-conducting solid oxide fuel cells (PC-SOFCs) after its chemical stability is improved significantly. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.