Chemical Stability and Electrochemical Properties of Perovskite Based Composite Electrolytes with High Ionic Conductivity

Abstract

Composite electrolytes consisting of protonic conducting perovskite oxide Sr(Y0.08Zr0.92)O3-d and Sr(Gd0.1Ce0.9)O3-d (SYZS and SGDC)  and alkaline carbonate (Li2CO3:Na2CO3, 1:1 molar ratio) were prepared through high energy milling followed by sintering techniques. The chemical and microstructural stability of these perovskite oxides with the mixed carbonates were studied by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) after reacting them at 690 °C for 1 h in air. The electrochemical performance of selected composites was evaluated using impedance spectroscopy in air. Among the two compositions, SrGdCeO3 shows degradation in contact with molten carbonates whereas SrYZrO3 is more stable. The corresponding composites have ionic conductivities (3.3x10-1 Scm-1 at 580 °C, in air) close to those reported for state-of-the-art ceria-based composite electrolytes. SrYZrO3+Li2CO3:Na2CO3 composites show chemical stability at operating temperatures in the order of 600 °C, standing as a potential candidate for intermediate temperature applications