Enhancement of proton conductivity through Yb and Zn doping in BaCe0.5Zr0.35Y0.15O3-δ electrolyte for IT-SOFCs

Abstract

The new compositions of BaCe0.5Zr0.3Y0.15-xYbxZn0.05O3-δ perovskite electrolytes (x = 0.1 and 0.15) were prepared by solid state synthesis and final sintering at 1500 °C. The obtained ceramics were investigated using X-ray diffraction, scanning electron microscopy, thermo-gravimetric analysis and impedance spectroscopy. The refinement of XRD data confirmed cubic crystal structure with Pm-3m space group for both samples. SEM morphology showed larger and compacted grains which enables obtaining of high density and high protonic conductivity. The relative densities of the samples were about 99% of the theoretical density after sintering at 1500 °C. The protonic conductivities at 650 °C were 2.8×10-4 S/cm and 4.2×10-3 S/cm for x = 0.1 and 0.15, respectively. The obtained results showed that higher Yb-content increases the ionic conductivity and both of these perovskites are promising electrolyte for intermediate temperature solid oxide fuel cells to get high efficiency, long-term stability and relatively low cost energy system.