JPWO2009119310A1 - Electrochemical equipment - Google Patents

Abstract

The electrochemical cell 1 includes a first electrode 9 that is in contact with a first gas, a solid electrolyte layer 6, and second electrodes 2A, 2B, and 2C that are in contact with a second gas. A gas flow path 8 through which the first gas flows is formed inside the first electrode 9. A through hole 4 (5) communicating with the gas flow path 8 is provided in the cell 1. The gas flow member 12 includes tubular portions 12b and 12c inserted through the through holes 4 (5) and a flange portion 12a having a seal surface facing one main surface 1a of the cell 1. The adjacent gas flow members 12 are not connected to each other, and a gas flow path 20 is formed by the plurality of gas flow members 12 and the through holes of the cell 1. The plurality of cells 1 are separated from each other by the gas flow member 12.

Description

TECHNICAL FIELD The present invention relates to an electrochemical device such as a solid oxide fuel cell.

In WO 2007/029860 A1, a fuel flow path is formed inside, for example, a fuel electrode of a ceramic electrochemical cell, and a solid electrolyte membrane and an air electrode membrane are formed on the fuel electrode. A gas supply hole and a gas discharge hole are provided in the cell itself, and a plurality of cells are directly stacked to form a stack. In forming the stack, the gas supply passages are formed by connecting the gas supply holes of adjacent cells, and the gas discharge passages are formed by connecting the gas discharge holes of the cells.
Also, in WO2008 / 123570 and 15th SOFC Research Presentation Abstract (December 5, 2006: SOFC Research Meeting), pages 212 to 215 “Power Generation Characteristics of Cell Stack with Built-in Channels” A gas supply pipe is inserted into the through hole of each cell. The gas supply pipes inserted into adjacent cells are connected to produce a connected gas supply structure. With this gas supply structure, a plurality of cells are fixed to form a stack. As a result, the individual cells are not in contact with each other and are supported by the connected gas supply structures, and the cells themselves do not act as structure holding members. Therefore, even if an external force is applied to the cell stack, an excessive stress is not easily applied to each cell.

However, as the inventor continued further research, WO 2008/123570 and the 15th SOFC Research Presentation Meeting Summary (issued on December 5, 2006: SOFC Research Meeting), Nos. 212-215 Page In the stack described in “Power generation characteristics of flow path built-in cell stack”, the cell has a flat plate shape, and a gas supply pipe is inserted into the through hole of the cell. Here, when an external force is applied to the connection structure including the gas supply pipe, a bending moment may be applied to the seal portion between the cell and the gas supply pipe depending on the state of the external force. If a minute crack is introduced into the seal portion between the cell and the gas supply pipe, the gas flowing inside the gas supply pipe may leak.
An object of the present invention is to prevent cracks from progressing in the sealing portion even when a bending moment or the like is locally applied to the sealing portion between the electrochemical cell and the gas flow structure.
The present invention relates to an electrochemical device including a plurality of ceramic electrochemical cells and a plurality of gas flow members.
The electrochemical cell includes a first electrode that is in contact with the first gas, a solid electrolyte layer, and a second electrode that is in contact with the second gas, and the gas flow path for flowing the first gas is the first. The cell is provided with a through-hole that communicates with the gas flow path. The gas flow member includes a tubular portion inserted through the through hole and a flange portion having a sealing surface sealed to one main surface of the cell. The adjacent gas flow members are not connected to each other, a gas flow path is formed by the plurality of gas flow members and the through holes of the cells, and the plurality of cells are separated from each other by the gas flow members. And
According to the present invention, the gas flow member includes a tubular portion inserted through the through hole, and a flange portion having a seal surface sealed to one main surface of the cell, and the seal surface is the cell. One main surface is sealed. The adjacent gas flow members are not connected to each other, and a gas flow path is formed by the plurality of gas flow members and the cell through holes.
In this structure, since each gas distribution member is not connected, it does not form an integral connection structure but is separated from each other. At the same time, the sealing surface of the gas flow member is sealed to the main surface of the cell. As a result, when compressive stress is applied in the cell arrangement direction when creating a stack, compressive stress acts to compress the sealing surface of the gas flow member and the main surface of the cell (the gas flow member is connected). Such compression stress does not work). As a result, even when an external force such as bending stress is concentrated on the seal portion between the gas flow member and the cell, the periphery of the seal surface is in a compressed state, so that the crack is caused between the flange portion and the tubular portion. It is difficult to progress beyond the branching portion, and gas leakage is unlikely to occur.

FIG. 1 is an exploded perspective view showing an electrochemical cell 1 according to an embodiment of the present invention.
2A is a cross-sectional view of the cell 1 of FIG. 1 taken along the line IIa-IIa, and FIG. 2B is a view of the cell 1 of FIG. 1 taken along the line IIb-IIb. FIG.
FIG. 3 is a cross-sectional view of the cell 1 of FIG. 1 taken along the line III-III.
4A is a cross-sectional view showing a state where the gas flow member 12 is fixed to the through hole 4 (or 5) of the cell 1 and sealed, and FIG. 4B is a cross-sectional view of FIG. It is the elements on larger scale of a).
FIG. 5 is a cross-sectional view showing a stack 21 formed by alternately arranging a plurality of gas flow members and a plurality of cells.
Fig.6 (a) is sectional drawing which shows the cell 1 and gas distribution member 12 which concern on other embodiment, FIG.6 (b) is the elements on larger scale of Fig.6 (a).
FIG. 7A is a schematic diagram for explaining a method of measuring the peel strength of the cell 1 from the gas flow member 12, and FIG. 7B is a state where the cell 1 is peeled from the gas flow member 12. It is a schematic diagram which shows.

In the present invention, the electrochemical cell is preferably plate-shaped. However, it is not limited to a flat plate shape, and may be a curved plate or a circular arc plate. The electrochemical cell includes a first electrode that contacts the first gas, a solid electrolyte membrane, and a second electrode that contacts the second gas.
Here, the first electrode and the second electrode are selected from an anode or a cathode. When one of these is an anode, the other is a cathode. Similarly, the first gas and the second gas are selected from oxidizing gas and reducing gas.
The oxidizing gas is not particularly limited as long as it is a gas that can supply oxygen ions to the solid electrolyte membrane, and examples thereof include air, diluted air, oxygen, and diluted oxygen. Examples of the reducing gas include H ₂ , CO, CH ₄ and a mixed gas thereof.
The electrochemical cell targeted by the present invention means a general cell for causing an electrochemical reaction. For example, the electrochemical cell can be used as an oxygen pump or a high temperature steam electrolysis cell. The high-temperature steam electrolysis cell can be used for a hydrogen production apparatus and a steam removal apparatus. Moreover, an electrochemical cell can be used as a decomposition cell for NOx and SOx. This decomposition cell can be used as a purification device for exhaust gas from automobiles and power generation devices. In this case, oxygen in the exhaust gas is removed through the solid electrolyte membrane, and NOx is electrolyzed and decomposed into N ₂ and O _2, and oxygen generated by this decomposition can also be removed. Moreover, with this process, water vapor in the exhaust gas is electrolysis produced hydrogen and oxygen, the hydrogen reduces NOx into N _2. In a preferred embodiment, the electrochemical cell is a solid oxide fuel cell.
The material of the solid electrolyte is not particularly limited, and any oxygen ion conductor can be used. For example, it may be yttria stabilized zirconia or yttria partially stabilized zirconia, and in the case of a NOx decomposition cell, cerium oxide is also preferable.
The material of the cathode is preferably a perovskite complex oxide containing lanthanum, more preferably lanthanum manganite or lanthanum cobaltite, and even more preferably lanthanum manganite. Lanthanum cobaltite and lanthanum manganite may be doped with strontium, calcium, chromium, cobalt (in the case of lanthanum manganite), iron, nickel, aluminum or the like.
As a material for the anode, nickel-magnesia alumina spinel, nickel-nickel alumina spinel, nickel-zirconia, platinum-cerium oxide, ruthenium-zirconia and the like are preferable.
The form of each electrochemical cell is not particularly limited. The electrochemical cell may consist of three layers: an anode, a cathode and a solid electrolyte layer. Alternatively, the electrochemical cell may have, for example, a porous body layer in addition to the anode, the cathode, and the solid electrolyte layer.
In the present invention, the electrochemical cell is provided with a gas flow path for flowing the first gas and a through hole. The form of the gas flow path, the number and location of the through holes are not particularly limited. Further, it is preferable to provide a plurality of through holes and separate the gas supply through hole and the gas discharge through hole.
The specific form of the tubular portion of the gas distribution member is not limited. The cross-sectional shape of the tubular portion may be, for example, a polygon such as a perfect circle, an ellipse, a triangle, a quadrangle, or a hexagon.
Hereinafter, the present invention will be described in more detail with reference to the drawings as appropriate.
FIG. 1 is an exploded perspective view showing an electrochemical cell 1 according to an embodiment of the present invention. 2A is a cross-sectional view of the cell of FIG. 1 taken along the line IIa-IIa, and FIG. 2B is a view of the cell of FIG. 1 taken along the line IIb-IIb. It is sectional drawing. FIG. 3 is a cross-sectional view of the cell of FIG. 1 taken along line III-III.
A gas flow path 8 for flowing a first gas is formed inside the first electrode 9 of the electrochemical cell 1. The first electrode 9 has a flat plate shape, and a solid electrolyte layer 6 is provided on each of both the main surface and side surfaces of the first electrode 9. A second electrode 2A, 2B or 2C is formed on each solid electrolyte layer 6 on both main surfaces. The second electrodes 2A, 2B, and 2C are exposed on both main surfaces of the cell 1, and the connection pad 3 that is electrically connected to the first electrode 9 is exposed at the center of the cell 1. Yes.
In the electrochemical cell 1, a first through hole 5 and a second through hole 4 are formed at predetermined positions. The through holes 5 and 4 communicate with the gas flow path 8. During operation of the cell, the first gas is supplied from the through hole 5. The gas enters the flow path as indicated by arrow A, is distributed in the flow path as indicated by arrow B, enters the through-hole 4 as indicated by arrow C, and exits from the cell.
4A is a cross-sectional view showing a state where the gas flow member 12 is fixed to the through hole 4 (or 5) of the cell 1 and sealed, and FIG. 4B is a cross-sectional view of FIG. It is the elements on larger scale of a). FIG. 5 is a cross-sectional view showing a stack 21 formed by alternately arranging a plurality of gas flow members and a plurality of cells.
As shown in FIG. 4, the gas flow member 12 is fixed to the cell. The gas flow member 12 is a gas supply member or a gas discharge member. Specifically, the gas flow member 12 includes a first tubular portion 12b, a second tubular portion 12c, and a flange portion 12a between them. A gas flow path 14 is formed in the gas flow member 12, and the gas flow path 14 communicates with the gas flow path 8 of the cell 1.
As shown in FIG. 4 (b), the tubular portion 12b is inserted into the through-hole 4 (or 5), the tubular portion 12b is opposed to the wall surface 15 of the cell, and the sealing surface 19 of the flange portion 12a is placed on the cell. It is made to oppose the main surface 1a. In this example, the sealing material 13 is sandwiched between the tubular portion 12b and the cell wall surface 15, and the sealing material 13 is sandwiched between the sealing surface 19 of the flange portion and the main surface 1a.
As shown in FIG. 5, a plurality of cells 1 and a plurality of gas flow members 12 are alternately installed and connected. Here, two adjacent cells 1 are connected by each gas flow member 12. That is, the first tubular portion 12b of the gas flow member 12 is inserted into the through hole 4 (5) of one cell 1 and sealed, and the second tubular portion 12c is inserted into the through hole 4 (5) of the adjacent cell 1. Insert and seal. As a result, the gas flow paths 8 of the adjacent cells are hermetically connected and mechanically fixed.
As a result, the gas flow paths 14 of the plurality of gas flow members 12 and the flow paths 8 of the cells communicate with each other to form the gas flow paths 20. The gas flow path 20 is used as a gas supply path or a gas discharge path. For example, when the gas flow path 20 is used as a gas supply path, the first gas is supplied as shown by an arrow E and is distributed into the flow paths 8. This gas flows as indicated by arrows A, B, and C shown in FIG. 1, and is discharged from the gas discharge path. In FIG. 5, the gas that has not been distributed from the flow path 20 into the flow path 8 is discharged out of the stack as indicated by an arrow F.
According to such an apparatus, adjacent cells are separated by the gas flow member and do not contact each other. Adjacent gas flow members 12 are also separated and do not contact each other. In this state, both the cell and the gas flow member function as a structure for holding the stack.
Here, when a holding structure in which the gas flow members are connected to each other is formed, a bending moment applied to the cell from the gas flow member may cause a crack along the seal interface between the gas flow member and the cell. . However, in the present invention, when stress is applied at the time of stacking as indicated by arrow G, the flow members 12 are separated from each other, so that compressive stress is applied in the direction of arrow G as shown in FIG. In this state, if a crack is generated in the direction of arrow D parallel to the sealing surface of the gas flow member, the crack is likely to stop around the branch portion of the flange portion 12a and the tubular portion 12b, and the crack to the gas flow path 14 occurs. Propagation is prevented. This cannot be achieved by only one of them due to a synergistic effect between the compressive stress applied in the direction of arrow G perpendicular to the seal surface and the branching of the flange portion 12a and the tubular portion 12b.
When connecting the cell and the gas flow member, thermal stress is applied to the weaker cell due to the difference in thermal expansion between the two materials, and this may cause the cell to break. In order to prevent this, the difference in thermal expansion coefficient between the gas flow member and the electrochemical cell is preferably 2 × 10 ⁻⁶ (/ K) or less, and the difference in thermal expansion coefficient between the gas discharge member and the electrochemical cell. Is preferably 2 × 10 ⁻⁶ (/ K) or less. These differences in thermal expansion coefficient were measured between 25 ° C and 800 ° C.
From this viewpoint, examples of the material of the gas flow member include zirconia, magnesia, spinel ceramics, and a composite material of these. Further, it may be a metal as long as it has oxidation resistance and reduction resistance at the operating temperature of the electrochemical cell, and may be a pure metal or an alloy, such as nickel, inconel, nichrome, etc. Nickel-based alloys, iron-based alloys such as stainless steel, and cobalt-based alloys such as stellite are preferred.
The material of the sealing material is not particularly limited, but it needs to have oxidation resistance and reduction resistance at the operating temperature of the electrochemical cell. Specifically, glass mainly composed of silica, crystallized glass, metal brazing and the like can be exemplified. Also, compression seals such as O-rings, C-rings, E-rings, metal jacket gaskets, and mica gaskets can be exemplified.
The difference between the thermal expansion coefficient of the sealing material and the thermal expansion coefficient of the cell is preferably 3.5 × 10 ⁻⁶ (/ K) or less. From this point of view, examples of the material of the sealing material include glass containing silica as a main component, crystallized glass, and metal brazing. Also, compression seals such as O-rings, C-rings, E-rings, metal jacket gaskets, and mica gaskets can be exemplified.
In a preferred embodiment, the gas flow member is made of ceramics, and the gas flow member and the electrochemical cell are co-sintered.
FIG. 6A is a cross-sectional view showing the cell 1 and the gas flow member 12 according to this embodiment, and FIG. 6B is a partially enlarged view of FIG. In this example, the cell 1 and the gas flow member 12 are co-sintered. Therefore, the ceramic structures of the two are continuously observed microscopically between the seal surface 19 of the gas flow member 12 and the cell main surface 1a, and between the outer wall surface of the tubular portion 12b and the wall surface 15 of the cell. is doing. Also in this case, as shown by an arrow G, a compressive stress is applied perpendicular to the seal surface. Even if the crack D is generated, the crack D is stopped in the vicinity of the branch portion between the flange portion 12a and the tubular portion 12b (or 12c) before reaching the gas flow path 14.

このように、本発明ではセルの剥離強度が高い。これは接合時の圧縮応力とガス流通部材の形状（フランジ部および挿通部）によって、クラックの進展が抑制されるからである。
なお、連結部品の表面形状、特にフランジ部のシール面の表面形状は特に限定されない。例えば、フランジ部に凹部を形成し、シール材を凹部中にも充填させ、フランジ部とシール材との熱膨張差によってシール材を凹部に係合することができる。
また、フランジ部のシール材に対する接触面を粗面化処理することもできる。このような粗面化処理を行うことによって、ガス供給菅（排出菅）とセルとの接着強度を増大させることができる。
この粗面化処理は特に限定されないが、耐水研磨紙，サンドブラストを例示できる。また、フランジ部のシール材への接触面の算術平均表面粗さＲａは、７０μｍ以上であることが好ましく、９０μｍ以上であることが更に好ましい。
本発明の特定の実施形態を説明してきたけれども、本発明はこれら特定の実施形態に限定されるものではなく、請求の範囲の範囲から離れることなく、種々の変更や改変を行いながら実施できる。Hereinafter, a connection structure of the cell 1, the gas supply pipe and the gas discharge pipe as shown in FIGS.
Specifically, the solid electrolyte 6 of the cell 1 was made of yttria-stabilized zirconia, the air electrode was made of lanthanum manganite, and the fuel electrode was made of Ni / YSZ cermet. The gas supply pipe and discharge pipe were made of magnesium oxide. The length of the flange portion 12a was 1 mm, the outer diameters of the tubular portions 12b and 12c were 24 mm, and the diameters of the through holes 4 and 5 were 9.2 mm. However, in the comparative example, the tubular portions 12b and 12c were not provided. In the embodiment, the tubular portions 12b and 12c and the flange portion 12a are provided.
The sealing material 13 was made of LiO ₂ —Al ₂ O ₃ —SiO ₂ glass. The thermal expansion coefficient of the cell is 12.9 × 10 ⁻⁶ (/ K), and the thermal expansion coefficients of the gas supply pipe and the discharge pipe are 13.2 × 10 ⁻⁶ (/ K). The thermal expansion coefficient is 10.0 × 10 ⁻⁶ (/ K). For bonding, the assembly of the cell, gas supply pipe, gas discharge pipe, and sealing material was heated at 1000 ° C. The bonding strength of each obtained bonded body was measured, and the results are shown in Table 1.
7A and 7B are schematic views showing a method for measuring the bonding strength. That is, as shown in FIG. 7A, the cell 1 was firmly fixed to the pedestal 30. Then, stress H was applied to the gas flow member 12. As shown in FIG. 7B, the stress H when the gas flow member 12 peels from the cell 1 was taken as the measured strength.

Thus, in the present invention, the peel strength of the cell is high. This is because the development of cracks is suppressed by the compressive stress at the time of joining and the shape of the gas flow member (flange portion and insertion portion).
In addition, the surface shape of a connection component, especially the surface shape of the sealing surface of a flange part is not specifically limited. For example, a concave portion can be formed in the flange portion, the sealing material can be filled into the concave portion, and the sealing material can be engaged with the concave portion due to a difference in thermal expansion between the flange portion and the sealing material.
Moreover, the contact surface with respect to the sealing material of a flange part can also be roughened. By performing such a surface roughening treatment, the adhesive strength between the gas supply rod (discharge rod) and the cell can be increased.
The surface roughening treatment is not particularly limited, and water-resistant abrasive paper and sand blasting can be exemplified. Further, the arithmetic average surface roughness Ra of the contact surface of the flange portion with the sealing material is preferably 70 μm or more, and more preferably 90 μm or more.
Although specific embodiments of the present invention have been described, the present invention is not limited to these specific embodiments and can be implemented with various changes and modifications without departing from the scope of the claims.

Claims (5)

An electrochemical device comprising a plurality of ceramic electrochemical cells and a plurality of gas flow members,
The electrochemical cell includes a first electrode in contact with the first gas, a solid electrolyte layer, and a second electrode in contact with the second gas, and a gas flow path for flowing the first gas Formed in the first electrode, a through hole communicating with the gas flow path is provided in the electrochemical cell;
The gas flow member includes a tubular portion inserted through the through-hole, and a flange portion having a seal surface sealed against one main surface of the electrochemical cell;
The adjacent gas flow members are not connected to each other, a gas flow path is formed by the plurality of gas flow members and the through holes of the plurality of electrochemical cells, and the plurality of electrochemical cells are Electrochemical device, characterized in that they are separated from each other by gas flow members.   2. The electrochemical device according to claim 1, wherein the gas flow member is made of ceramics, and the gas flow member and the electrochemical cell are co-sintered.   The electrochemical device according to claim 1, further comprising a sealing material provided between the sealing surface of the gas flow member and the one main surface of the electrochemical cell.   The apparatus according to claim 1, wherein the gas flow member is a gas supply member.   The apparatus according to claim 1, wherein the gas flow member is a gas discharge member.

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