Shoji Otoshi

High power density solid oxide electrolyte fuel cells using Ru/Y2O3 stabilized zirconia cermet anodes

Ru/YSZ cermet SOFC anodes were fabricated using the EVD method. Ru has high sintering resistivity compared with Ni. During the power generation tests at 1273 K the Ru/YSZ cermet anode showed high activity for hydrogen oxidation compared with conventional Ni/YSZ cermet anodes. Especially in the high current density of a maximum of 3200 mA/cm2 the ac polarization value was reduced to approximately 200 mV. Tubular type SOFCs were made by depositing 10 micro m thick 10 mol% yttriastabilized zirconia (YSZ) electrolyte films on porous La(Sr)MnOx cathode tubes using the EVD process and then making a Ru/YSZ cermet anode on YSZ. The cells had the highest power generation density with a maximum density of 1550 mW/cm2. After the power generation test of approximately one week including several thermal cycles, the anode polarization was unchanged and there was no change in the Ru metal grain size.

Fabrication of high power density tabular type solid oxide fuel cells

Abstract Tubular-type solid oxide fuel cell (SOFC) with interconnector has been successfully fabricated, with a maximum single cell power density of 0.9 W/cm2, the highest value reported so far. A self supporting La(Sr)MnOx tube was used for the cathode. The La(Sr)CrOx interconnector was made using the laser oblation method. The yttria-stabilized zirconia (YSZ) electrolyte and Ru/YSZ cermet anode were fabricated by the electrochemical vapor deposition (EVD) process.

High Performance Solid Oxide Fuel Cell Cathode Fabricated by Electrochemical Vapor Deposition

La(Sr)MnO[sub 3] cathodes have been investigated as high temperature oxygen reduction electrodes in the solid oxide fuel cells (SOFCs). The cathodes consist of 10 mole percent of yttria stabilized zirconia (YSZ) thin film electrolyte layer deposited on a porous La[sub 0.81]Sr[sub 0.09]MnO[sub 3] tube using the electrochemical vapor deposition method. The La(Sr)MnO[sub 3]/YSZ cathodes have different electrochemical properties from those fabricated with the sintering method. The cathode polarization was about 1 mV at a current density of 1.5 A/cm[sup 2] in oxygen at 1,000 C. This type of cathode has an extremely large phase boundary and large interfacial capacitance (more than 1 F/cm[sup 2]) which is approximately proportional to the oxygen partial pressure.

High-power-density-solid-oxide-electrolyte fuel cells

This paper reports that, the authors succeeded in fabricating a solid-oxide-electrolyte fuel cell, with the highest power-generation density, with a maximum single-cell-level density of 1550 mW/cm{sup 2}. This cell was made by depositing a 10{mu}m thick 10 mol% (m/o) yttria stabilized zirconia (YSZ) electrolyte layer on a porous La(Sr)MnO{sub x} cathode tube using the electrochemical vapor deposition method and then making a Ru/YSZ cermet anode on top of it.

Reaction mechanism of electrochemical‐vapor deposition of yttria‐stabilized zirconia film

The reaction mechanism for electrochemical‐vapor deposition of yttria‐stabilized zirconia was studied. Yttria‐stabilized zirconia films were deposited on porous La(Sr)MnOx using the electrochemical‐vapor‐deposition process. The distribution of yttria concentration through the film was investigated by means of secondary‐ion‐mass spectroscopy and x‐ray microanalysis and found to be nearly constant. The deposition rate was approximately proportional to the minus two‐thirds power of the film thickness, the one‐third power of the partial pressure of ZrCl4/YCl3 mixed gas, and the two‐thirds power of the product of the reaction temperature and the electronic conductivity of yttria‐stabilized zirconia film. These experimental results were explained by a model for electron transport through the YSZ film and reaction between the surface oxygen and the metal chloride on the chloride side of the film, both of which affect the deposition rate. If the film thickness is very small, the deposition rate is thought to be c...

Preparation of La1−xSrxCrO3−δ film by laser ablation method

Abstract La−xSrxCrO3−δ films were fabricated on yttria stabilized zirconia (YSZ) and La(Sr)MnO3 polycrystal substrates using the laser ablation method. At a substrate temperature of 973 K and an oxygen pressure of 10−4 Torr, the resultant films were porefree and contained no detectable oxygen vacancy. The chemical composition of the films almost agreed with the target. Film crystallinity depended on the crystal structure of the substrates. The film formed on YSZ substrate showed remarkable primary particle growth resulting from heat-treatment at 1473 K for 5 h in air. When a film was formed on the LaMnO3 substrate, which has a crystal structure similar to that of LaCrO3, under the same conditions as above, neither crystal structure change nor particle growth was observed from heat-treatment at 1473 K.

Preparation of La(Sr)CrO3 − δ thin film interconnector by high deposition rate laser ablation method

Abstract A-site deficient La(Sr)CrO 3 − δ thin film interconnectors were successfully fabricated on porous La(Sr)MnO x tubes using high deposition rate laser ablation. The La(Sr)CrO 3 − δ films obtained by this method are dense and void-free. The film deposition rate was about 10 μm/min. The substrate could easily be masked in order to deposit the films in the desired shape. The substrate tube was heated at 873–1073 K. As the substrate temperature was much lower than the sintering temperature of the substrate tube, the porous micro-structures of the substrate tube were maintained. The difference in chemical composition between the film and the target was negligible.