Preparation of Nanoparticle Core−Shell Electrolyte Materials for Proton Ceramic Fuel Cells

Abstract

The sinterability of yttrium-doped barium zirconate (BZY) has been improved through an original synthesis approach giving a core-shell type arrangement in which nanoparticulate BZY is enrobed by a thin coating of yttrium-doped barium cerate (BCY). A flash combustion route was first used to prepare BZY10 (10% yttrium-doped) in a nanopowder form with average particle diameter of 12-17 nm. The nanoparticles were then dispersed in a hydrogel generated from 3,3 0 ,3 00 -nitrilotripropionic acid complexed metal (yttrium, barium, cerium) acrylates. After thermal elimination of the organic moieties, a material of novel macroscopic architecture is obtained, which can be densified (apparent density g 97%) by sintering compacted pellets at 1300 °C for 10 h, i.e. some 200 °C lower than is generally used to densify BZY. X-ray diffraction indicates that two phases corresponding to BCY10 and BZY10 are present and that no discernible migration of atoms occurs between the zirconate core and the cerate shell. Proton conductivities of densified pellets were determined in a moist nitrogen atmosphere in the range 300-600 °C using impedance spectroscopy. The total conductivity is in the range 4.1 Â 10 -4 S/cm (300 °C)-9.5 Â 10 -3 S/cm (600 °C), which is an order of magnitude higher than that of BZY10, prepared under equivalent conditions and the core-shell material displayed improved stability against carbonate formation in a CO 2 atmosphere. The densification, proton conductivity, and CO 2 uptake properties of the novel core-shell structured proton ceramic all differ from those of yttrium-doped barium zirconate cerate solid solution containing a similar ratio of yttrium, zirconium, and cerium, and of a physical mixture of BCY10 and BZY10, and show an improved set of properties compared with those of BCY10 or BZY10 alone.

Solution Combustion Synthesis of Nanoscale Materials

“…SCS was also employed to prepare novel proton-conducting SOFC electrolytes. , Khani et al developed a unique core–shell nanostructure of yttrium-doped barium zirconate (BZY)–yttrium-doped barium cerate (BCY) . They first prepared BZY core with average particle diameter 15 nm using combustion of solutions containing barium, zirconium, and yttrium nitrates as oxidizer and glycine as fuel.…”

“…308,309 Khani et al developed a unique core− shell nanostructure of yttrium-doped barium zirconate (BZY)− yttrium-doped barium cerate (BCY). 308 They first prepared BZY core with average particle diameter 15 nm using combustion of solutions containing barium, zirconium, and yttrium nitrates as oxidizer and glycine as fuel. In the second stage, a thin layer (∼10 nm) of BCY was deposited on BZY using a hydrogel containing acrylates of yttrium, barium, and cerium.…”

Progress in proton‐conducting oxides as electrolytes for low‐temperature solid oxide fuel cells: From materials to devices

“…On the other hand, since cerates and zirconates are mutually soluble, the cerate‐zirconate solid solutions have been intensively explored for the development of electrolytes with sufficient proton conductivity and decent chemical stability under fuel cell operating conditions 46−54 . For example, replacing a certain amount of Ce in the cerate by Zr is a well‐recognized strategy that was proposed in 1999 55 .…”

Effect of fluorine, chlorine and bromine doping on the properties of gadolinium doped barium cerate electrolytes

“…Among the samples, Br doped BCG exhibits the best chemical stability on the basis of weight gain. It should be noted that weight gain of BCGCl is the lowest during heating-up and then exceeds BCGBr during cooling down, which possibly is due to slow It is well known that it is due to the basicity of the material that BCG easily reacts with CO 2 to form barium carbonate and oxides [27,39]. Therefore, reducing basicity of BCG is an effective method to improve its chemical stability.…”

“…The proton conductors of core-shell structured BaZr 0.9 Y 0.1 O 2.95 (BZY10):-BaCe 0.9 Y 0.1 O 2.95 (BCY10) were prepared via solid state reaction in combination with sol-gel method. The core-shell structured materials display higher conductivity and better chemical stability than that of BZY10/BCY10 physical mixture or solid solution with same composition [38,39]. It was considered that the conductivity increase is achieved by the improvement of the sintering property of BZY10 through coating BZY10 grains by a thin layer of BCY10.…”