Impedance investigation of BaCe0.85Y0.15O3-delta properties for hydrogen conductor in fuel cells

International audienceThe influence of the sintering conditions on the electrochemical properties of the proton conducting electrolyte BaCe0.85Y0.15O3-delta (BCY15) and Ni - based BCY15 cermet anode for application in high temperature proton conducting fuel cell are investigated by electrochemical impedance spectroscopy. The results show that at lower sintering temperatures due to the formation of parasitic Y2O3 phase an increase of both the electrolyte and electrode resistances is observed. This effect is strongly reduced by enhancement of the sintering temperature. The obtained BCY15 conductivity (sigma = 2.5x10(-2) S/cm at 700 degrees C) is comparable with that of the best proton conducting materials, while the BCY15-Ni cermet (with ASR = 2.5 Omega cm(2) at 700 degrees C) needs further optimization. The results of impedance investigations of BCY15 as proton conducting electrolyte and cermet anode have been applied in development of innovative high temperature dual membrane fuel cell

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National audienceno abstrac

Elaboration et réactivité interfaciale d'oxydes pérovskites à base de Lanthane Strontium Chrome Ruthénium (LSCrRu) comme composés d'anode de piles à combustible à température intermédiaire (ITSOFC)

Cette étude apporte des données sur l'intérêt des chromites de lanthane strontium dopés au ruthénium La1-xSrxCr1-yRuyO3 (LSCrRu) comme anode de pile à combustible ITSOFC. La synthèse sous champ micro-onde d'oxydes mixtes a permis la mise en forme de demi-cellules et cellules complètes modèles par pulvérisation cathodique magnétron et par sérigraphie. Les propriétés de reformage de CH4 ont pu être étudiées dans un dispositif mono-chambre couplé à un spectromètre de masse en collaboration avec l'Institut de REcherche Hydro-Québec. La réactivité à l'interface anode/électrolyte a été analysée par SIMS et XRD sur demi-cellules modèles vieillies sous H2 à 800C. Elle a permis de préciser la chimie du film après traitement. Les cellules complètes, testées en condition de fonctionnement, ont mis en évidence, après dissolution sélective de LSCrRu, une modification de la microstructure à l'interface anode/électrolyte. Des analyses XPS et SEM-EDX n'ont pas montré de réactivité chimique.New data on the interest of ruthenium doped lanthanum strontium chromite La1-xSrxCr1-yRuyO3 (LSCrRu) as anode in ITSOFC are presented. Microwave synthesis of mixed oxides allowed shaping of half-cells and complete cells using sputtering and screen printing methods. LSCrRu methane reforming property had been studied in a mono-chamber system coupled with a mass spectrometer in collaboration with Institut de REcherche Hydro-Québec. Anode/electrolyte interfacial reactivity had been analysed using SIMS and XRD on half cells models after ageing under H2 at 800C. This experiment gave the chemical composition of the film after treatment. Complete cells, tested under working conditions, highlighted, after selective dissolution of LSCrRu film, a microstructure modification at anode/electrolyte interface. XPS and SEM-EDX techniques did not show chemical reactivity.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

Ce0.9Gd0.1O2−x for Intermediate Temperature Solid Oxide Fuel Cells: Influence of Cathode Thickness and Anode Functional Layer on Performance

International audienceThe performances of Intermediate Temperature Solid Oxide Fuel Cell (IT-SOFC) anode-supported planar cells with a 10 cm2 active surface were studied versus the combination of cathode thickness and the presence of an Anode Functional Layer (AFL). The temperature range was 500 to 650 °C, and Gd0.1Ce0.9O2−x (GDC) was used as the electrolyte material, Ni-GDC as the anode material, and La0.6Sr0.4Co0.2Fe0.8O3−d (LSCF48) as the cathode material. The power density, conductivity, and activation energy of different samples were determined in order to investigate the influence of the cathode thickness and AFL on the performance. These results showed an improvement in the performances when the AFL was not present. The maximum power density reached 370 mW·cm−2 at 650 °C for a sample with a cathode thickness of 50 µm and an electrolyte layer that was 20 µm thick. Moreover, it was highlighted that a thinner cathode layer reduced the power density of the cell

Development of anode supported Single Chamber Solid Oxide Fuel Cells running in air/methane mixture

International audienceSingle Chamber Solid Oxide Fuel Cells (SCFC) show a growing interest and are the concern of more and more papers. In such device, anode and cathode are ex-posed to a gas mixture of fuel (hydrocarbon) and oxidant (air) so that no more sealing with electrolyte is necessary. Their operating principle is based on the different catalytic activities of anode and cathode: Ideally, the anode has to be active for the oxidation of fuel while the cathode should present only a strong electro-activity for oxygen reduction. In this paper, we present the development of an anode supported SCFC device running in air/methane mixture characterized by their volume ratio, Rmix = CH4/O2

<i>In situ</i> reduction and evaluation of anode supported single chamber solid oxide fuel cells

International audienceSingle chamber anode-supported fuel cells are investigated under several methane-oxygen-nitrogen atmospheres at intermediate temperatures (500°C-700°C). Ce0.9Gd0.1O1.95 (CGO) is chosen as electrolyte and deposited by screen-printing onto NiO-CGO anode pellets. A cathode composed of 70 wt% La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and 30 wt% of CGO is screen-printed onto the electrolyte. Thermogravimetric analyses of anode reduction are performed at 700 °C. Carbon deposition is observed under diluted methane but a successful reduction is obtained after an initialization under diluted methane followed by a final treatment under methane-to-oxygen ratio (Rmix) of 2. Anode-supported fuel cells are investigated regarding the working temperature and Rmix. Two types of cells are prepared with modifications of the electrolyte microstructure. For both cells tested, the Open Circuit Voltage (OCV), the power density and the fuel utilization increase when Rmix and temperature decrease. The electrolytes of both cells have a porous microstructure and the electrolyte of the second cell, with the highest thickness, brings better performances. At 600 °C for Rmix = 0.6, the maximum power density is improved from 60 for the first cell to 160 mW cm−2 for the second cell. Comparing the fuel utilization, it increases from 3% for the first cell to 6% for the second one for the same testing conditions

Synthesis of Y-doped BaZrO3 proton conducting electrolyte material by a continuous hydrothermal process in supercritical conditions: Investigation of the formation mechanism and electrochemical performance

International audienc

Chemical Degradation of the La0.6Sr0.4Co0.2Fe0.8O3−δ/Ce0.8Sm0.2O2−δ Interface during Sintering and Cell Operation

International audienceA complete cell consisting of NiO-Ce0.8Sm0.2O3−δ//Ce0.8Sm0.2O3−δ//(La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ elaborated by a co-tape casting and co-sintering process and tested in operating fuel cell conditions exhibited a strong degradation in performance over time. Study of the cathode–electrolyte interface after cell testing showed, on one hand, the diffusion of lanthanum from (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ into Sm-doped ceria leading to a La- and Sm-doped ceria phase. On the other hand, Ce and Sm diffused into the perovskite phase of the cathode. The grain boundaries appear to be the preferred pathways of the cation diffusion. Furthermore, a strontium enrichment was clearly observed both in the (La0.6Sr0.4)0.95Co0.2Fe0.8O3−δ layer and at the interface with electrolyte. X-ray photoelectron spectroscopy (XPS) indicates that this Sr-rich phase corresponded to SrCO3. These different phenomena led to a chemical degradation of materials and interfaces, explaining the decrease in electrochemical performance