Processing and characterization of proton conducting yttrium doped BaCeO3-BaZrO3 electrolyte for protonic ceramic fuel cells

Abstract

To address the refractory nature of proton conducting yttrium–doped BaCeO3–BaZrO3 as a membrane in electrochemical devices, the influence of sintering additive on the sintering behaviors were investigated, attaining the densification of electrode membrane assembly (MEA) without detrimental effect on the electrical conductivity. In order to suppress the elements consumption by the reaction sintering of the membrane and sintering additive, the resultant transient phase (BaNiOx) was directly introduced as a sintering additive. Also, the proper amount of sintering additive (BaNiOx) was uniformly infiltrated during the sintering process through the thermal decomposition phenomenon of the yttrium stabilized transient phase (BaY2NiO5). To match the sintering shrinkage behavior of the electrode membrane assembly via commercial ceramic process, sintering behavior of electrode substrate was adjusted to that of membrane by controlling particle size distribution of electrode powder. Here we present the fabrication of a physically thin, structurally dense, and chemically homogeneous electrolyte, BaCe0.55Zr0.3Y0.15O3-δ (BCZY3), through facile anode–assisted densification of the electrolyte on a structurally and compositionally uniform anode support, resulting in breakthroughs in performance and scalability. By this procedure, a 5x5 cm2 large-area thin-film membrane electrode assembly was fabricated without compromise of material properties, a maximum power density of 1.3 Wcm-2 and the ohmic resistance of 0.09 Ωcm2 were achieved at 600 ℃ in fuel cell application.