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

Abstract

A novel proton conductor, BaCe 0.95Tb 0.05O 3 −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 °C or greater. The electrical conductivities of the BCTb perovskite mainly result from protons and are 6.51 × 10 −3−2.0 × 10 −2 S cm −1 in the temperature range of 600–850 °C with the activation energy of 41.95 kJ mol −1. A Ni-BCTb∣BCTb∣LSCF(La 0.6Sr 0.4Co 0.2Fe 0.8O 3-α)-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 °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.