Fabrication and Characterization of a Tubular Solid Oxide Fuel Cell with Impregnated Perovskite Electrodes

Abstract

Thanks to large efficiency and ability to work in both fuel cell and electrolysis mode Solid Oxide Cells (SOCs) could become a vital technology in the transition to the carbon-neutral energy sector based on hydrogen. However, large cost and low durability constrain their full-scale commercialization. These challenges are tackled in the present work. Tubular cells are produced by a simple and inexpensive method, suitable for mass production. The cells showed excellent activity, stability and redox resistance due to tubular design and fully ceramic electrodes. Thermal shock resistance testing showed that the cell is resistant to rapid temperature changes.A thick supporting layer of the porous backbone was cast first, and a thin layer of electrolyte over it. After rolling into a tubular shape, the assembly was co-sintered and impregnated with functional perovskite materials. Co-casting allowed to achieve a strong interface and reduce the thickness of electrolyte. The impregnation gave the possibility to deposit a perovskite in temperature much lower than in state-of-art methods, preventing the undesirable reaction with zirconia electrolyte and reducing their densification, producing more active spatial microstructures with large surface area. Moreover, such electrodes are more thermally compatible with electrolyte as their bulk TEC is mainly controlled by the porous backbone made of the same material as the electrolyte.Yttria-stabilized zirconia (Zr0.92Y0.16O2.08, 8YSZ) is used as the electrolyte, for the fuel electrode nickel doped lanthanum calcium titanate (La0.43Ca0.37Ni0.06Ti0.94O3- γ, LCNT) was impregnated onto a porous 8YSZ backbone, while on the air electrode a lanthanum strontium ferrite (La0.8Sr0.2FeO3, LSF) was applied. These materials offer high activity and stability for a relatively low price. Electrochemical impedance spectroscopy (EIS), current-voltage (I-V) and potentiostatic measurements were carried out to characterize cell performance and cell’s stability during the test. The electrochemical testing showed improvement in the cell performances after electrochemical poling at high potential, due to facilitated LCNT reduction and exsolution of nickel nanoparticles.The cheap fabrication method, competitive performance, attracting redox stability and thermal shock resistance, braking the major limitation for SOFC applicability, making it even suitable to be used in portable applications.