Fabrication and Characterization of BaCexZr1-x-yYyO3-δ powder and functional layers for proton conducting fuel cells

Abstract

t Proton Conducting Fuel Cells (PCFCs) are an emerging sub-class of Solid Oxide Fuel Cells (SOFCs) with great potential for lowering the operating temperature to 400- 600 °C and achieving higher fuel utilization due to the generation of water is on the opposite of fuel side, avoiding the dilution of fuel gas effectively. Unlike oxygen ion conducting SOFC, PCFC is characterized by proton conducting ceramic (PCC) as electrolyte material. Due to the high brittleness of ceramic materials, the traditional electrolyte- or anode-supported cell designs suffer from the poor mechanical stability and thereby the size of the cell is restricted. On account of these limitations of ceramic substrate, porous metal substrate was used here due to the advantage of mechanical stability. However, the high sintering temperature, which is characteristic for PCC materials to obtain a dense electrolyte, is incompatible with the nature of substrate used for Metal Supported Cells (MSCs). One solution to this problem is to apply Pulsed Laser Deposition (PLD) method to fabricate a dense thin-film electrolyte at reduced temperature. In order to make the deposition of dense thin-film electrolyte possible, comprehensive work has been done in this work. BaCexZr1-x-yYyO3-δ ceramic powder with appropriate composition was synthesized via wet-chemical method. To be more specific, colloidal sol was synthesized with zirconium n-propoxide (Zr(OC3H7)4) and 2-propanol under reflux condition at 90o C. Then the metal nitrate salts i.e. barium nitrate, yttrium nitrate and cerium nitrate were added respectively with corresponding stoichiometry. The obtained gel was dried and calcined to produce final BCZY powders. Different functional layers such as La0.8Sr0.2MnO3 (LSM) diffusion barrier layer, BCZY-NiO anode functional layer and BCZY nano-layer were developed to form a multi-layered cell architecture on ITM metal substrate, which can be used to support further deposition of dense BCZY electrolyte through Pulsed Laser Deposition. The obtained final BCZY powder along with different functional layers were characterized through X-ray diffractometer (XRD), thermogravimetric analysis (TGA) in specific atmosphere, Energy-dispersive X-ray spectroscopy (EDX) analyses and scanning electron microscopy (SEM). Keywords: proton conducting fuel cell, wet-chemical processing, BCZY, metal supported SOFC, diffusion barrier lay