Single-chamber Solid Oxide Fuel Cell Research Articles

140 燃料にメタノールを用いた一室型固体酸化物燃料電池におけるカソード材の評価(環境工学,一般講演)

140 燃料にメタノールを用いた一室型固体酸化物燃料電池におけるカソード材の評価(環境工学,一般講演)

La2Mo2O9-Based Electrolyte: Ion Conductivity and Anode-Supported Cell under Single Chamber Conditions

We demonstrate the applicability of LAMOX as an electrolyte for solid oxide fuel cells (SOFC) by preparing two anode-supported cells based on La0.9Dy0.1Mo2O9 and La0.9Dy0.1Mo1W1O9, and operating at 625°–700°C under single chamber conditions. The two cells, supported by a composite of NiO and Gd-doped ceria (GDC), are initialized with a porous Ni+GDC disk to catalyze the partial oxidation reaction of methane. The partially oxidized methane reduces NiO to Ni catalyst and activates the cell at 650°C. A typical membrane electrode assembly of the single chamber SOFC cell consists of a 60-μm-thick La0.9Dy0.1Mo2O9 electrolyte, an anode of Ni+GDC, and a cathode of lanthanum strontium cobalt ferrite. Its peak power measures 220 mW/cm2 at 700°C in a tubular chamber of 15 mm in diameter, with the total methane/air flow rate of 350 mL/min and CH4:O2=2:1.

Development of Single Chamber Solid Oxide Fuel Cells (SCFC)

AbstractSingle Chamber Solid Oxide Fuel Cells (SCFC) have been prepared using an electrolyte as support (Ce0.9Gd0.1O1.95 named GDC). Anode (Ni‐GDC) and different cathodes (Sm0.5Sr0.5CoO3 (SSC), Ba0.5Sr0.5Co0.2Fe0.8O3 (BSCF) and La0.8Sr0.2MnO3 (LSM)) were placed on the same side of the electrolyte. All the electrodes were deposited using screen‐printing technology. A gold collector was also deposited on the cathode to decrease the over‐potential. The different materials and fuel cell devices were tested under propane/air mixture, after a preliminary treatment under hydrogen to reduce the as‐deposited nickel oxide anode. The results show that SSC and BSCF cathodes are not stable in these conditions, leading to a very low open circuit voltage (OCV) of 150 mV. Although LSM material is not the more adequate cathode regarding its high catalytic activity towards hydrocarbon conversion, it has a better chemical stability than SSC and BSCF. Ni‐GDC‐LSM SCFC devices were elaborated and tested; an OCV of nearly 750 mV could be obtained with maximum power densities around 20 mW cm–2 at 620 °C, under air–propane mixture with C3H8/O2 ratio equal to 0.53.

Impact of reforming catalyst on the anodic polarisation resistance in single-chamber SOFC fed by methane

This paper emphasises the electrochemical and catalytic properties of a Ni–10% GDC (10% gadolinium-doped ceria) cermet anode of a single-chamber solid oxide fuel cell (SC-SOFC). Innovative coupling of electrochemical impedance spectroscopy with gas chromatography measurements was carried out to characterise the anode material using an operando approach. The experiments were conducted in a symmetric anode/electrolyte/anode cell prepared by slurry coating resulting in 100 μm-thick anode layers. The electrochemical performance was assessed using a two-electrode arrangement between 400 °C and 650 °C, in a methane-rich atmosphere containing CH 4, O 2 and H 2O in a 14:2:6 volumetric ratio. The insertion of a Pt–CeO 2 based catalyst with high specific surface area inside the cermet layer was found to promote hydrogen production from the Water Gas Shift reaction and consequently to improve the electrochemical performances. Indeed, a promising polarisation resistance value of 12 Ω cm 2 was achieved at 600 °C with a catalytic loading of only 15 wt.%.

Effects of the single chamber SOFC stack configuration on the performance of the single cells

A single chamber solid oxide fuel cell (SC-SOFC) micro-stack with three series-wound cells has been prepared and operated in methane–oxygen–nitrogen mixture. A maximum power output of 282 mW was generated at the furnace temperature of 800 °C. A mutual effect was found among the three cells. Cell 2 between Cell 1 and Cell 3 produced a maximum power density of 215 mWcm − 2 which was higher than other cells. The heat effect and flow geometry were the main factors in inducing the difference among the three single cells.

Nickel-Based Anodes for Single-Chamber Solid Oxide Fuel Cells: A Catalytic Study

Single-chamber solid oxide fuel cells (SOFCs) are an alternative concept to traditional SOFCs. Conventional anodes, which consist of a cermet of metallic Ni and an ionic conductor, have to work under a mixture of hydrocarbon and oxygen. This paper presents a catalytic study of oxidation by and nickel. The influences of temperature and oxygen to propane ratio on the nickel oxidation state are clarified, thanks to catalytic tests and electrical conductivity measurements. The results show that the temperature must be higher than a critical value to maintain the nickel particles in the metallic state. Furthermore, at high temperatures, the conversion of the initial mixture leads to the water-gas-shift equilibrium.

Tests for the Use of La2Mo2O9‐based Oxides as Multipurpose SOFC Core Materials

AbstractThe mixed ionic–electronic conductivity under dilute hydrogen, the stability and the catalytic activity under propane:air type mixtures of a series of LAMOX oxide‐ion conductors have been studied. The effect of exposure to dilute hydrogen on the conductivity of the β‐La2(Mo2 – yWy)O9 series at 600 °C depends on tungsten content: almost negligible for the highest (y = 1.4), it is important for La2Mo2O9 (y = 0). In propane:air, all tested LAMOX electrolytes are stable at 600–700 °C, but get reduced when water vapour is present. La2Mo2O9 is the best oxidation catalyst of the series, with an activity comparable to that of nickel.The catalytic activity of other tested LAMOX compounds is much lower, (La1.9Y0.1)Mo2O9 showing a deactivation phenomenon. These results suggest that depending on composition, La2(Mo2 – yWy)O9 compounds could be either electrolytes in single‐chamber SOFC and dual‐chamber micro‐SOFC (y = 1.4) or anode materials in dual‐chamber SOFC (low y) or oxidation catalysts in SOFCs operating with propane (y = 0).

Influence of water vapor on performance of co-planar single chamber solid oxide fuel cells

Influences of feeding gas compositions on the performance of co-planar, single chamber solid oxide fuel cells (SC-SOFCs) are investigated with emphasis on the role of water vapor. The maximum open circuit voltage (OCV) and peak power density are obtained at a methane-to-oxygen ratio of 3.5 under the wet gas condition, and a stoichiometric ratio of 2.0 for methane partial oxidation under the dry gas condition. In addition to the partial oxidation of methane on the anode and electrocatalytic reactions, both steam reforming and methane combustion occur on the anode and cathode, respectively, in the presence of water vapor. Local volume expansion and a rise in temperature associated with these parasitic reactions intensify inter-mixing of the reactant and product gases by which the OCV and power density drastically deteriorate with decreasing anode-to-cathode gap distance, as confirmed by impedance analysis for the LSM-YSZ|YSZ|LSM-YSZ symmetrical cell.

Performance of the Single-Chamber Solid Oxide Fuel Cell with a La0.75Sr0.25Cr0.5Mn0.5O3 − δ-Based Perovskite Anode

In this paper, perovskite oxide (LSCM) mixed with a small fraction Ni has been used as the anode of single-chamber solid oxide fuel cell(s) operating in a methane–oxygen mixture. The anode is prepared by an ion impregnation method, whereby a proper mixed solution with metal nitrates and urea is incorporated into the porous presintered yttria-stabilized zirconia (YSZ) anode matrix. After sintering at , the impregnated materials change to unique microparticles adhered to the YSZ matrix. These microparticles themselves become porous after reducing in single-chamber conditions, and this porous character is expected to facilitate the anode reaction because it would improve the gas transport. The influence of the environmental temperature and gas composition on the cell performance is also investigated. A maximum power density of is achieved at a gas composition of and a furnace temperature of . The redox cycling test demonstrates that the stability of the LSCM-based anode is better compared to the conventional Ni-YSZ anode.

Microfabrication of single chamber SOFC with co-planar electrodes via multi-step photoresist molding with thermosetting polymer

In this paper, we report a simple and novel microfabrication method, named photoresist molding with thermosetting polymer (PRM-TP) which is very efficient for fabricating multiple ceramic structures with sub-micron to several millimeter scaled dimension. PRM-TP is a novel hybrid process combining lithographic tools and customized ceramic slurry process which can utilize the advantages of micro-scale ceramic fabrication with well controlled microstructure. In order to demonstrate general usefulness of PRM-TP, we applied this process for the construction of single chamber solid oxide fuel cell (SC-SOFC) with co-planar electrodes. According to the cell test at 500 °C under single chamber operation condition with pre-mixed gas of methane and air, the open circuit voltage and power output of SC-SOFC reached 205 mV and 67 mW/cm 2, respectively.

Numerical modelling of methane-powered micro-tubular, single-chamber solid oxide fuel cell

An experimentally validated, two-dimensional, axisymmetric, numerical model of micro-tubular, single-chamber solid oxide fuel cell (MT-SC-SOFC) has been developed. The model incorporates methane full combustion, steam reforming, dry reforming and water-gas shift reaction followed by electrochemical oxidation of produced hydrogen within the anode. On the cathode side, parasitic combustion of methane along with the electrochemical oxygen reduction is implemented. The results show that the poor performance of single-chamber SOFC as compared to the conventional (dual-chamber) SOFC (in case of micro-tubes) is due to the mass transport limitation on the anode side. The gas velocity inside the micro-tube is far too low when compared to the gas-chamber inlet velocity. The electronic current density is also non-uniform over the cell length, mainly due to the short length of the anode current collector located at the cell outlet. Furthermore, the higher temperature near the cell edges is due to the methane combustion (very close to the cell inlet) and current collection point (at the cell outlet). Both of these locations could be sensitive to the silver current collecting wire as silver may rupture due to cell overheating.

Single Chamber SOFC Based on LDMW Electrolyte and Its In Situ Anode Initialization

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Evaluation of Anode Architectures for Single-Chamber SOFC by Impedance Spectroscopy Coupled with Gas Chromatography

not Available.

Alternative Perosvkite Materials as Cathode Materials for Single-Chamber SOFC

not Available.

Screening of Ceria-Based Catalysts for Methane Reforming in Intermediate Temperature Single-Chamber SOFC

not Available.

Single-Chamber Solid Oxide Fuel Cell Technology—From Its Origins to Today’s State of the Art

In single-chamber solid oxide fuel cells (SC-SOFCs), both anode and cathode are situated in a common gas chamber and are exposed to a mixture of fuel and oxidant. The working principle is based on the difference in catalytic activity of the electrodes for the respective anodic and cathodic reactions. The resulting difference in oxygen partial pressure between the electrodes leads to the generation of an open circuit voltage. Progress in SC-SOFC technology has enabled the generation of power outputs comparable to those of conventional SOFCs. This paper provides a detailed review of the development of SC-SOFC technology.

Preparation of Single-Chamber Solid Oxide Fuel Cell by Co-Pressing and Direct Forming Process

Co-pressing and direct forming process has been developed for the preparation of a single-chamber solid oxide fuel cell (SC-SOFC),which consists of 8%(x) Y2O3-stabilized ZrO2 (YSZ) electrolyte,Ni-YSZ cermet anode and La0.7Sr0.3MnO3 (LSM) cathode.Scanning electron microscopy (SEM) showed tight integration between the cathode and electrolyte and good loading performance of LSM on the YSZ three-dimensional framework.The thickness of the YSZ electrolyte film,the anode and the cathode was about 50,600 and 100 μm,respectively.The effects of temperature (T),number of catalyst loading layers (n) and the volume ratio of CH4 and O2 (Rmix=V(CH4)/V(O2)) on the SC-SOFC performance was studied.At T =800 C,n=2 and Rmix=2,the single cell performed the best,the open voltage was 0.95 V,the maximum current density was 130 mA·cm-2 and the maximum power density was 30 mW·cm-2.

A Configuration for Improving the Performance of Coplanar Single-Chamber Solid Oxide Fuel Cell

A configuration for the coplanar, single-chamber solid oxide fuel cell has been proposed and operated successfully in a methane-oxygen mixture (CH 4 :0 2 = 2:1) with a total flow of 300 mL min -1 . It was fabricated by attaching the Ni/yttria-stabilized zirconia (YSZ) anode and the Sm 0.2 Ce 0.8 O 1.9 -impregnated La 0.7 Sr 0.3 MnO 3 cathode in two parallel grooves of the YSZ substrate. With the electrolyte wall fabricated between the anode and the cathode, the configuration obviously extends the conductive channel of oxygen ion transport and forms a gas separator between the electrodes, leading to a remarkable reduction in ohmic resistance, an elevation of open-circuit voltage, and, ultimately, an improved performance.

Low Temperature Operation of Single Chamber Fuel Cell Using BaCeO3 Electrolyte Film as Proton Conductor Grown by Helicon Plasma Sputtering

Thin film single chamber solid oxide fuel cell (SC-SOFC) with Barium Cerium Oxide (BaCeO3) electrolyte film as proton conductor, grown by the helicon plasma sputtering, was studied to determine the power generation property at lower operating temperatures between 200 and 400°C in the gas mixtures of hydrogen and oxygen. An SC-SOFC with a BaCeO3 electrolyte film thickness of 5 μm could be operated at 400°C in the gas mixtures of hydrogen and oxygen and had a maximum open circuit voltage of 455 mV. However, a V-I property at 400°C of SC-SOFC was considerably poor as a development index of SOFC, because the cell resistance with a several kΩ was due mainly to the interface reaction resistance of between the Pt catalytic electrodes and an amorphous electrolyte film.

Nickel Based Anodes of Single Chamber Solid Oxide Fuel Cells: A Catalytic Study

Single chamber solid oxide fuel cells (SCFC) are an alternative concept to traditional SOFC's. Conventional anodes, which consist of a cermet of metallic Ni and ionic conductor, have to work under a mixture of hydrocarbon and oxygen. This paper presents a catalytic study of C3H8 oxidation by Ce0.9Gd0.1O1.95 and nickel. The influence of temperature and oxygen to propane ratio on the nickel oxidation state are clarified thanks to catalytic tests and electrical conductivity measurements. The results show that the temperature must be higher than a critical value in order to maintain the nickel particles in the metallic state. Furthermore, at high temperature, the conversion of the initial mixture leads to the water-gas-shift equilibrium.