JP7641449B2 - Electrochemical Cell - Google Patents

Description

The present invention relates to an electrochemical cell.

In electrochemical cells such as electrolysis cells or fuel cells, a structure in which a cell body is supported by a metal plate is known. For example, the electrochemical cell disclosed in Patent Document 1 has an electrode layer, an electrolyte layer, and a counter electrode layer stacked in that order on a metal plate. The metal plate has communication holes for supplying and exhausting air to and from the electrode layer.

International Publication No. 2018/181926

However, because the thermal expansion coefficient of the laminate composed of the electrode layer and electrolyte layer is smaller than that of the metal plate, when the laminate is cooled after the electrolyte layer is formed on the electrode layer, the laminate deforms together with the metal plate. As a result, the laminate may be damaged, such as cracked or chipped.

The objective of the present invention is to suppress damage to the laminate of the electrode layer and the electrolyte layer.

The electrochemical cell according to a first aspect of the present invention comprises a metal plate, a cell main body, and a deformation suppression layer. The metal plate has a first main surface, a second main surface, and a through hole communicating with the first main surface and the second main surface. The cell main body includes a laminate constituted by an electrode layer formed on the first main surface and an electrolyte layer formed on the electrode layer. The deformation suppression layer is formed on the second main surface. The thermal expansion coefficient of the laminate is smaller than the thermal expansion coefficient of the metal plate. The thermal expansion coefficient of the deformation suppression layer is smaller than the thermal expansion coefficient of the metal plate.

The electrochemical cell according to the second aspect of the present invention relates to the first aspect described above, wherein the deformation suppression layer covers only a portion of the second main surface.

The electrochemical cell according to the third aspect of the present invention relates to the first or second aspect described above, and the cell main body has a counter electrode layer arranged on the opposite side of the electrode layer with respect to the electrolyte layer, and the thickness of the deformation suppression layer is less than or equal to the thickness of the cell main body.

The electrochemical cell according to a fourth aspect of the present invention is related to any one of the first to third aspects and further comprises a flow path member for forming a gas flow path between the metal plate and the flow path member, and a joint portion for joining the metal plate and the flow path member. In a cross section perpendicular to the outer edge of the second main surface, the ratio of the width of the joint portion to the sum of the thicknesses of the metal plate, the cell main body portion, and the deformation suppression layer is 0.05 or more and 1.0 or less.

The electrochemical cell according to a fourth aspect of the present invention is related to any one of the first to fourth aspects and further includes a flow path member for forming a gas flow path between the metal plate. The deformation suppression layer is made of an insulating material.

The electrochemical cell according to the fifth aspect of the present invention relates to any one of the first to fourth aspects, in which the deformation suppression layer is made of a conductive material, and a conductive portion is disposed within the communicating hole to electrically connect the deformation suppression layer and the electrode layer.

According to the present invention, damage to the laminate of the electrode layer and the electrolyte layer can be suppressed.

FIG. 1 is a cross-sectional view of an electrolysis cell according to an embodiment. FIG. 2 is a partially enlarged view of FIG. FIG. 4 is a cross-sectional view of an electrolysis cell according to a first modified example.

An electrolytic cell (an example of an electrochemical cell) according to an embodiment will be described with reference to the drawings. In this embodiment, a ceramic solid oxide electrolytic cell (SOEC) will be described as an example of an electrolytic cell. In the following description, the solid oxide electrolytic cell will be abbreviated as "electrolytic cell."

Figure 1 is a cross-sectional view of an electrolytic cell 1 according to an embodiment. As shown in Figure 1, the electrolytic cell 1 comprises a metal plate 10, a cell main body 20, a deformation suppression layer 30 and a flow path member 40.

(Metal plate 10)
The metal plate 10 supports the cell main body 20. In this embodiment, the metal plate 10 is formed in a plate shape. The metal plate 10 may be flat or curved. The metal plate 10 only needs to be able to support the cell main body 20, and the thickness of the metal plate 10 is not particularly limited, but may be, for example, 0.1 mm or more and 2.0 mm or less.

The metal plate 10 is made of a metal material. For example, the metal plate 10 is made of an alloy material containing Cr (chromium). Examples of such metal materials that can be used include Fe-Cr alloy steel (stainless steel, etc.) and Ni-Cr alloy steel. The Cr content in the metal plate 10 is not particularly limited, but can be 4% by mass or more and 30% by mass or less.

The metal plate 10 may contain Ti (titanium) or Zr (zirconium). The content of Ti in the metal plate 10 is not particularly limited, but may be 0.01 mol% or more and 1.0 mol% or less. The content of Zr in the metal plate 10 is not particularly limited, but may be 0.01 mol% or more and 0.4 mol% or less. The metal plate 10 may contain Ti as _TiO2 (titania) or Zr as Zr (zirconium).

The metal plate 10 may have a chromium oxide film on its surface. The chromium oxide film covers at least a portion of the surface of the metal plate 10. The chromium oxide film may cover at least a portion of the surface of the metal plate 10, but may cover substantially the entire surface.

In this embodiment, the thermal expansion coefficient of the metal plate 10 is larger than that of the laminate 20a described below and is also larger than that of the deformation suppression layer 30. The value of the thermal expansion coefficient of the metal plate 10 is not particularly limited, but can be, for example, 10×10 ⁻⁶ /°C or more and 18×10 ⁻⁶ /°C or less.

As shown in FIG. 1, the metal plate 10 has a first main surface 11, a second main surface 12, and a plurality of communicating holes 13. A cell main body 20 is disposed on the first main surface 11 of the metal plate 10. The second main surface 12 of the metal plate 10 is provided on the opposite side to the first main surface 11. A deformation suppression layer 30 is formed on the second main surface 12 of the metal plate 10. In addition, a flow path member 40 is joined to the second main surface 12 of the metal plate 10.

The multiple communication holes 13 are formed in a region corresponding to the hydrogen electrode layer 21 described below. Each communication hole 13 communicates with the first main surface 11 and the second main surface 12. Each communication hole 13 opens to the first main surface 11 and the second main surface 12. The opening of each communication hole 13 on the first main surface 11 side is covered by the hydrogen electrode layer 21. In this embodiment, the inside of each communication hole 13 is hollow. However, a portion of the hydrogen electrode layer 21 may penetrate into each communication hole 13.

The area of the communication hole 13 in plan view can be, for example, 0.00005 ^mm2 or more and 1 ^mm2 or less. When the shape of the communication hole 13 in plan view is substantially circular, the diameter of the communication hole 13 can be, for example, 10 μm or more and 1000 μm or less. The shape of the communication hole 13 in plan view may be rectangular.

The through holes 13 can be formed by mechanical processing (e.g., punching), laser processing, or chemical processing (e.g., etching). In addition, since the through holes 13 do not need to be formed along the thickness direction of the metal plate 10, the metal plate 10 may be made of a porous metal having a mesh-like pore.

The metal plate 10 may have a chromium oxide film covering the surface. The chromium oxide film may cover at least a portion of the surface of the metal plate 10, but may also cover the entire surface. The chromium oxide film may also cover the inner wall surface of the communication hole 13.

The chromium oxide film contains chromium oxide as a main component. "Containing chromium oxide as a main component" means that chromium oxide accounts for 70% by weight or more of the entire chromium oxide film. The thickness of the chromium oxide film is not particularly limited, but can be, for example, 0.1 μm or more and 20 μm or less.

(Cell body 20)
1, the cell body 20 is disposed on the first main surface 11 of the metal plate 10. The cell body 20 has a hydrogen electrode layer 21 (cathode), an electrolyte layer 22, a reaction prevention layer 23, and an oxygen electrode layer 24 (anode). The cell body 20 includes a laminate 20a constituted by the hydrogen electrode layer 21 and the electrolyte layer 22. The hydrogen electrode layer 21 is an example of an "electrode layer" according to the present invention, and the oxygen electrode layer 24 is an example of a "counter electrode layer" according to the present invention.

The hydrogen electrode layer 21, electrolyte layer 22, reaction prevention layer 23 and oxygen electrode layer 24 are laminated in this order from the metal plate 10 side. However, the cell main body 20 does not have to have the reaction prevention layer 23.

In this embodiment, the thermal expansion coefficient of the laminate 20a is smaller than the thermal expansion coefficient of the metal plate 10. The value of the thermal expansion coefficient of the laminate 20a is not particularly limited, but can be, for example, 9×10 ⁻⁶ /° C. or more and 13×10 ⁻⁶ /° C. or less.

The thermal expansion coefficient of the laminate 20a is calculated based on the following formula (A).

Thermal expansion coefficient of laminate 20a = (thermal expansion coefficient of hydrogen electrode layer 21 x thickness of hydrogen electrode layer 21 x Young's modulus of hydrogen electrode layer 21 + thermal expansion coefficient of electrolyte layer 22 x thickness of electrolyte layer 22 x Young's modulus of electrolyte layer 22) ÷ (thickness of hydrogen electrode layer 21 x Young's modulus of hydrogen electrode layer 21 + thickness of electrolyte layer 22 x Young's modulus of electrolyte layer 22) ... (A)

[Hydrogen electrode layer 21]
The hydrogen electrode layer 21 is formed on the first main surface 11 of the metal plate 10. The hydrogen electrode layer 21 is provided so as to cover an area of the metal plate 10 in which the plurality of communication holes 13 are provided. A portion of the hydrogen electrode layer 21 may extend into each communication hole 13 of the metal support 10.

A source gas is supplied to the hydrogen electrode layer 21 through each communication hole 13 of the metal plate 10. The source gas contains at least H ₂ O. When the source gas contains only H ₂ O, the hydrogen electrode layer 21 generates H ₂ from the source gas in accordance with the electrochemical reaction of water electrolysis shown in the following formula (1).

Hydrogen electrode layer 6: H ₂ O+2e ⁻ →H ₂ +O ²⁻ (1)

When the source gas contains CO ₂ in addition to H ₂ O, the hydrogen electrode layer 21 produces H ₂ , CO, and O ²⁻ from the source gas in accordance with the co-electrolytic electrochemical reaction shown in formula (2) below.

・Hydrogen electrode layer 21: CO ₂ +H ₂ O+4e ^- →CO+H ₂ +2O ² -...(2)

The hydrogen electrode layer 21 is made of a conductive porous material. The hydrogen electrode layer 21 may have oxide ion conductivity. The hydrogen electrode layer 21 may be made of, for example, 8 mol % yttria-stabilized zirconia (8YSZ), calcia-stabilized zirconia (CSZ), scandia-stabilized zirconia (ScSZ), gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), (La, Sr) (Cr, Mn) O ₃ , (La, Sr) TiO ₃ , Sr ₂ (Fe, Mo) ₂ O ₆ , (La, Sr) VO ₃ , (La, Sr) FeO ₃ , a mixed material of two or more of these, or a composite material of one or more of these and NiO.

The porosity of the hydrogen electrode layer 21 is not particularly limited, but may be, for example, 5% to 70%. The thickness of the hydrogen electrode layer 21 is not particularly limited, but may be, for example, 1 μm to 100 μm. The thermal expansion coefficient of the hydrogen electrode layer 21 is not particularly limited, but may be, for example, 10×10 ⁻⁶ /° C. to 13×10 ⁻⁶ /° C. The Young's modulus of the hydrogen electrode layer 21 is not particularly limited, but may be, for example, 50 GPa to 200 GPa.

The thickness of the hydrogen electrode layer 21 is obtained by arithmetically averaging the thicknesses of the hydrogen electrode layer 21 measured at three locations that divide the hydrogen electrode layer 21 into four equal parts in the surface direction on a cross section along the thickness direction of the hydrogen electrode layer 21. The thermal expansion coefficient of the hydrogen electrode layer 21 is obtained by separating the electrolyte layer 22 from the hydrogen electrode layer 21 by micromachining using a focused ion beam (FIB) device, and then measuring the lattice expansion of the hydrogen electrode layer 21 using a high-temperature X-ray diffraction (XRD) device.

The method for forming the hydrogen electrode layer 21 is not particularly limited, and may be a firing method, a spray coating method (thermal spraying method, aerosol deposition method, aerosol gas deposition method, powder jet deposition method, particle jet deposition method, cold spray method, etc.), a PVD method (sputtering method, pulsed laser deposition method, etc.), a CVD method, etc.

[Electrolyte layer 22]
1 , the electrolyte layer 22 is disposed between the hydrogen electrode layer 21 and the oxygen electrode layer 24. In this embodiment, since the cell body 20 has the reaction prevention layer 23, the electrolyte layer 22 is interposed between the hydrogen electrode layer 21 and the reaction prevention layer 23.

The electrolyte layer 22 is disposed so as to cover the entire hydrogen electrode layer 21. The outer periphery of the electrolyte layer 22 is bonded to the first main surface 11 of the metal plate 10. This ensures airtightness between the hydrogen electrode layer 21 side and the oxygen electrode layer 24 side, eliminating the need for a separate seal between the metal plate 10 and the electrolyte layer 22.

The electrolyte layer 22 transfers O ^2- generated in the hydrogen electrode layer 21 to the oxygen electrode layer 24. The electrolyte layer 22 is a dense body having oxide ion conductivity. Examples of oxide ion conductive materials include YSZ (yttria stabilized zirconia, for example, 8YSZ), GDC (gadolinium doped ceria), ScSZ (scandia stabilized zirconia), SDC (samarium doped ceria), LSGM (lanthanum gallate), and composite materials thereof.

The porosity of the electrolyte layer 22 is not particularly limited, but may be, for example, 0.1% or more and 7% or less. The thickness of the electrolyte layer 22 is not particularly limited, but may be, for example, 1 μm or more and 100 μm or less. The value of the thermal expansion coefficient of the electrolyte layer 22 is not particularly limited, but may be, for example, 9×10 ⁻⁶ /° C. or more and 12×10 ⁻⁶ /° C. or less. The value of the Young's modulus of the electrolyte layer 22 is not particularly limited, but may be, for example, 150 GPa or more and 250 GPa or less.

The thickness of the electrolyte layer 22 is obtained by arithmetically averaging the thicknesses of the electrolyte layer 22 measured at three points that divide the electrolyte layer 22 into four equal parts in the surface direction in a cross section along the thickness direction of the electrolyte layer 22. The thermal expansion coefficient of the electrolyte layer 22 is obtained by sequentially separating the oxygen electrode layer 24 and the reaction prevention layer 23 from the electrolyte layer 22 by micromachining using an FIB device, and then measuring the lattice expansion of the electrolyte layer 22 using an XRD device.

The electrolyte layer 22 is formed by a method including a high-temperature process. The high-temperature process is a process in which all or part of at least one of the metal plate 10, the hydrogen electrode layer 21, and the electrolyte layer 22 is heated to 100°C or higher. Examples of methods including a high-temperature process include a baking method, a spray coating method, a PVD method, and a CVD method.

[Reaction prevention layer 23]
The reaction prevention layer 23 is disposed on the electrolyte layer 22. The reaction prevention layer 23 is interposed between the electrolyte layer 22 and the oxygen electrode layer 24. The reaction prevention layer 23 prevents a reaction between the constituent material of the oxygen electrode layer 24 and the constituent material of the electrolyte layer 22, resulting in the formation of a reaction layer with high electrical resistance.

The reaction prevention layer 23 is made of a material having oxide ion conductivity. The reaction prevention layer 23 can be made of a ceria-based material such as GDC or SDC.

The porosity of the reaction prevention layer 23 is not particularly limited, but may be, for example, 0% to 50%. The thickness of the reaction prevention layer 23 is not particularly limited, but may be, for example, 3 μm to 50 μm. The thermal expansion coefficient of the reaction prevention layer 23 is not particularly limited, but may be, for example, 9×10 ⁻⁶ /° C. to 13×10 ⁻⁶ /° C.

The reaction prevention layer 23 is formed by a method including a high-temperature process. Examples of the method including a high-temperature process include a baking method, a spray coating method, a PVD method, and a CVD method.

[Oxygen electrode layer 24]
The oxygen electrode layer 24 is disposed on the opposite side of the hydrogen electrode layer 21 with respect to the electrolyte layer 22. In this embodiment, since the reaction prevention layer 23 is disposed between the electrolyte layer 22 and the oxygen electrode layer 24, the oxygen electrode layer 24 is connected to the reaction prevention layer 23. If the reaction prevention layer 23 is not disposed between the electrolyte layer 22 and the oxygen electrode layer 24, the oxygen electrode layer 24 is connected to the electrolyte layer 22.

The oxygen electrode layer 24 produces O ₂ from O ²⁻ transferred from the hydrogen electrode layer 21 via the electrolyte layer 22 in accordance with the chemical reaction of the following formula (3).

Oxygen electrode layer 24: 2O ²⁻ →O ₂ +4e ⁻ (3)

The oxygen electrode layer 24 is made of a porous material having oxide ion conductivity and electrical conductivity, and may be made of a composite material of _one or more of (La,Sr)(Co,Fe)O3, (La,Sr) _FeO3 , La(Ni,Fe) _O3 , (La,Sr) _CoO3 , and (Sm,Sr) _CoO3 and an oxide ion conductive material (such as GDC).

The porosity of the oxygen electrode layer 24 is not particularly limited, but may be, for example, 20% to 60%. The thickness of the oxygen electrode layer 24 is not particularly limited, but may be, for example, 1 μm to 100 μm. The thermal expansion coefficient of the oxygen electrode layer 24 is not particularly limited, but may be, for example, 10×10 ⁻⁶ /° C. to 16×10 ⁻⁶ /° C.

The method for forming the oxygen electrode layer 24 is not particularly limited, and a firing method, a spray coating method, a PVD method, a CVD method, etc. can be used.

[Deformation suppression layer 30]
1, the deformation suppression layer 30 is formed on the second main surface 12 of the metal plate 10. The deformation suppression layer 30 has a plurality of communication paths 31. The communication paths 31 penetrate the deformation suppression layer 30 in the thickness direction. The communication paths 31 communicate with a gas flow path 41 (described later) and the communication holes 13 of the metal plate 10. In this embodiment, the inside of each communication path 31 is hollow.

The raw material gas supplied to the hydrogen electrode layer 21 passes through the communication passage 31 of the deformation suppression layer 30 and the communication hole 13 of the metal plate 10 in sequence and is supplied to the hydrogen electrode layer 21. The product gas generated in the hydrogen electrode layer 21 passes through the communication hole 13 of the metal plate 10 and the communication passage 31 of the deformation suppression layer 30 in sequence and is discharged to the gas flow path 41 described later.

In this embodiment, the thermal expansion coefficient of the deformation suppression layer 30 is smaller than the thermal expansion coefficient of the metal plate 10. This makes it possible to suppress deformation of the laminate 20a together with the metal plate 10. Specifically, this is as follows.

When the hydrogen electrode layer 21 is formed on the first main surface 11 of the metal plate 10, and the electrolyte layer 22 is formed by a high-temperature process and then cooled to room temperature, the thermal expansion coefficient of the laminate 20a is smaller than that of the metal plate 10, so the metal plate 10 tends to shrink more than the laminate 20a. However, since the metal plate 10 is restrained by the laminate 20a, it cannot shrink, and the center of the first main surface 11 tends to deform so as to protrude toward the laminate 20a. Therefore, in this embodiment, a deformation suppression layer 30 is formed on the second main surface 12 of the metal plate 10. Since the thermal expansion coefficient of the deformation suppression layer 30 is smaller than that of the metal plate 10, the metal plate 10, which tends to deform toward the laminate 20a, can be held by the deformation suppression layer 30. That is, at least a part of the stress generated between the metal plate 10 and the laminate 20a can be offset by the stress generated between the metal plate 10 and the deformation suppression layer 30. In this manner, by reducing the stress difference occurring on both main surfaces of the metal plate 10, it is possible to suppress deformation of the laminate 20a together with the metal plate 10.

The thermal expansion coefficient of the deformation suppression layer 30 may be equal to the thermal expansion coefficient of the cell main body 20, or may be larger or smaller than the thermal expansion coefficient of the cell main body 20. The value of the thermal expansion coefficient of the deformation suppression layer 30 is not particularly limited, but may be, for example, 5×10 ⁻⁶ /° C. or more and 13×10 ⁻⁶ /° C. or less.

The deformation suppression layer 30 may be made of an insulating material or a conductive material. When the deformation suppression layer 30 is made of an insulating material, even if the interconnector 43 described later and the deformation suppression layer 30 accidentally come into contact with each other, it is possible to prevent an unintended conductive path from being formed between the deformation suppression layer 30 and the interconnector 43. Therefore, in the configuration shown in FIG. 1, it is preferable that the deformation suppression layer 30 is made of an insulating material.

Examples of the insulating material constituting the deformation suppression layer 30 include Al ₂ O ₃ , ZrO ₂ , SiO ₂ , and TiO ₂ . Examples of the conductive material constituting the deformation suppression layer 30 include a ceramic material having electronic conductivity in a reducing atmosphere, or a composite of the ceramic material and a metal material. Examples of the ceramic material having electronic conductivity in a reducing atmosphere include TiO ₂ , ZnO ₂ , and CeO ₂ . Examples of the metal material include metals such as Ni, Cu, and Co, or oxides thereof. The deformation suppression layer 30 may be made of the same material as the hydrogen electrode layer 21 or the electrolyte layer 22.

It is preferable that the deformation suppression layer 30 covers only a portion of the second main surface 12 of the metal plate 10. By appropriately designing the planar shape of the deformation suppression layer 30, it is possible to prevent stress from concentrating on the deformation suppression layer 30 and causing damage. For example, the deformation suppression layer 30 does not have to be formed in the area of the second main surface 12 where the communication holes 13 open. Alternatively, the deformation suppression layer 30 does not have to be formed in the area where the flow path member 40 is joined.

The thickness of the deformation suppression layer 30 is not particularly limited, but is preferably equal to or less than the thickness of the cell body 20. This reduces the proportion of ceramics in the electrolytic cell 1, thereby suppressing a decrease in the toughness of the electrolytic cell 1 as a whole, which is a laminated structure. As a result, damage to the electrolytic cell 1 can be suppressed.

The porosity of the deformation suppression layer 30 is not particularly limited, and the deformation suppression layer 30 may be a porous layer or a dense layer.

It is preferable that the deformation suppression layer 30 is formed before the deposition of the electrolyte layer 22. For example, the deformation suppression layer 30 may be formed simultaneously with the deposition of the hydrogen electrode layer 21, or may be formed simultaneously with the deposition of the electrolyte layer 22. Alternatively, the deformation suppression layer 30 may be formed before the deposition of the hydrogen electrode layer 21, or may be formed after the deposition of the hydrogen electrode layer 21 and before the deposition of the electrolyte layer 22.

[Flow path member 40]
The flow path member 40 is joined to the metal plate 10. The space between the metal plate 10 and the flow path member 40 becomes a gas flow path 41. The gas flow path 41 opens on the metal plate 10 side and is covered by the metal plate 10. The gas flow path 41 communicates with each communication path 31 of the deformation suppression layer 30. In this embodiment, a raw material gas is supplied to the gas flow path 41.

The flow path member 40 can be made of a metal material that can be used for the metal plate 10.

As shown in FIG. 1, the flow path member 40 has a frame body 42 and an interconnector 43. The frame body 42 is joined to the second main surface 12 of the metal plate 10. The frame body 42 is an annular member that surrounds the side periphery of the gas flow path 41. The frame body 42 surrounds the side periphery of the deformation suppression layer 30. The interconnector 43 is a plate-shaped member that electrically connects the electrolytic cell 1 in series with an external power source or another electrolytic cell. The interconnector 43 is joined to the frame body 42. The interconnector 43 faces the deformation suppression layer 30.

In this embodiment, the frame body 42 and the interconnector 43 are separate components, but the frame body 42 and the interconnector 43 may also be an integrated component.

Here, Fig. 2 is a partially enlarged view of Fig. 1. Fig. 2 shows a cross section perpendicular to the outer edge 10a of the second main surface 12 of the metal plate 10.

As shown in FIG. 2, the metal plate 10 is joined to the flow path member 40 via a joint 45. The joint 45 seals the gap between the metal plate 10 and the flow path member 40. The joint 45 is formed in a ring shape along the gap between the metal plate 10 and the flow path member 40. The joint 45 is arranged to surround the gas flow path 41.

The joint 45 is made of a conductive material. For example, the joint 45 can be formed by applying a metal paste containing SUS430 or the like to the second main surface 12 of the metal plate 10, and firing (e.g., 850°C, 1 hour) the flow path member 40 in a state of being in close contact with the metal paste. Alternatively, the joint 45 can be formed by welding the metal plate 10 and the flow path member 40 in a state of being in close contact with each other.

It is preferable that the ratio (W1/T1) of the width W1 of the joint 45 to the sum T1 of the thicknesses of the metal plate 10, the cell body 20, and the deformation suppression layer 30 is 0.05 or more and 1.0 or less. This makes it possible to suppress deformation and damage of the electrolytic cell 1 as follows. First, the deformation suppression layer 30 with a small thermal expansion coefficient is formed on the second main surface 12 of the metal plate 10. Therefore, if the flow path member 40 is firmly joined to the second main surface 12 of the metal plate 10, the electrolytic cell 1 will be deformed due to the difference in thermal expansion coefficient with the flow path member 40. Therefore, by setting the ratio (W1/T1) to 0.05 or more and 1.0 or less, the joint 45 becomes easily deformed, and the thermal stress generated between the metal plate 10 and the flow path member 40 can be absorbed by the deformation of the joint 45. As a result, it is possible to suppress the electrolytic cell 1 from warping and the flow path member 40 from peeling off.

The results of confirming the effect in the electrolytic cell 1 shown in Figure 1 are shown in Table 1. In Samples No. 1 to 8, a square (100 mm x 100 mm) metal plate 10 was used, the thickness of the metal plate 10 was 0.3 mm, the thickness of the cell main body 20 was 0.1 mm, and the thickness of the deformation suppression layer 30 was 0.03 mm.

As shown in Table 1, in samples No. 1 to 6, in which the ratio (W1/T1) was 0.05 or more and 1.0 or less, warping of the electrolytic cell 1 and peeling of the flow path member 40 were suppressed. On the other hand, in sample No. 7, in which the ratio (W1/T1) was less than 0.05, peeling of the flow path member 40 occurred. Also, in sample No. 8, in which the ratio (W1/T1) was greater than 1.0, significant warping of the electrolytic cell 1 occurred.

(Modification)
Although the embodiments of the present invention have been described above, the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention.

[Modification 1]
In the above embodiment, the inside of the communication hole 13 of the metal plate 10 is hollow, but as shown in FIG. 3, a conductive part 50 may be disposed inside the communication hole 13. The conductive part 50 is connected to the hydrogen electrode layer 21. The conductive part 50 is made of a porous material and has gas permeability. The porosity of the conductive part 50 may be, for example, 5% to 70%. The conductive part 50 is made of a conductive material and assists in electrical connection between the metal plate 10 and the hydrogen electrode layer 21. Note that, although the conductive part 50 is filled inside the communication hole 13 in FIG. 3, the conductive part 50 may be formed in a film shape so as to cover the inner wall surface of the communication hole 13.

Here, when the deformation suppression layer 30 is made of a conductive material, it is preferable that the conductive portion 50 electrically connects the deformation suppression layer 30 and the hydrogen electrode layer 21, as shown in Figure 3. Specifically, it is preferable that the conductive portion 50 is arranged not only inside the communication hole 13 formed in the metal plate 10, but also inside the communication path 31 formed in the deformation suppression layer 30, and is connected to both the hydrogen electrode layer 21 and the deformation suppression layer 30. This can significantly improve the electrical connection between the metal plate 10 and the hydrogen electrode layer 21.

The material of the conductive portion 50 is not particularly limited, and may be, for example, a conductive porous material that can be used in the hydrogen electrode layer 21. The conductive portion 50 may be formed integrally with the hydrogen electrode layer 21. Alternatively, the material of the conductive portion 50 may be a conductive material that can be used in the deformation suppression layer 30. The conductive portion 50 may be formed integrally with the deformation suppression layer 30.

[Modification 2]
In the above embodiment, the hydrogen electrode layer 21 functions as a cathode and the oxygen electrode layer 24 functions as an anode, but the hydrogen electrode layer 21 may function as an anode and the oxygen electrode layer 24 may function as a cathode. Specifically, the positions of the hydrogen electrode layer 21, the reaction prevention layer 23, and the oxygen electrode layer 24 are interchanged, and a source gas is caused to flow over the outer surface of the hydrogen electrode layer 21. In this case, the oxygen electrode layer 24 serves as the electrode layer according to the present invention, and the hydrogen electrode layer 21 serves as the counter electrode layer according to the present invention.

[Modification 3]
In the above embodiment, the electrolysis cell 1 has been described as an example of an electrochemical cell, but the electrochemical cell is not limited to the electrolysis cell. The electrochemical cell is a general term for an element in which a pair of electrodes are arranged so that an electromotive force is generated from an overall oxidation-reduction reaction to convert electrical energy into chemical energy, and an element for converting chemical energy into electrical energy. Therefore, the electrochemical cell may be a solid oxide fuel cell (SOFC) using oxide ions or protons as carriers. In this case, the fuel electrode (anode) is an example of an "electrode layer", and the air electrode (cathode) is an example of a "counter electrode layer".

Reference Signs List 1 Electrolysis cell 10 Metal plate 11 First main surface 12 Second main surface 13 Communication hole 20 Cell body 21 Hydrogen electrode layer 22 Electrolyte layer 23 Reaction prevention layer 24 Oxygen electrode layer 30 Deformation suppression layer 31 Communication path 40 Flow path member 41 Gas flow path 42 Frame 43 Interconnector 50 Conductive portion

Claims (6)

A metal plate having a first main surface, a second main surface, and a through hole communicating with the first main surface and the second main surface;
a cell body having a laminate including an electrode layer formed on the first main surface and an electrolyte layer formed on the electrode layer;
a deformation suppression layer formed on the second main surface;
Equipped with
The thermal expansion coefficient of the laminate is smaller than the thermal expansion coefficient of the metal plate,
The thermal expansion coefficient of the deformation suppression layer is smaller than the thermal expansion coefficient of the metal plate.
Electrochemical cell.
The deformation suppression layer covers only a portion of the second main surface.
10. The electrochemical cell of claim 1.
the cell body portion has a counter electrode layer disposed on the opposite side of the electrode layer with respect to the electrolyte layer;
The thickness of the deformation suppression layer is equal to or less than the thickness of the cell main body portion.
3. An electrochemical cell according to claim 1 or 2.
a flow path member for forming a gas flow path between the metal plate and the flow path member;
a joining portion that joins the metal plate and the flow path member;
Further equipped with
In a cross section perpendicular to the outer edge of the second main surface, the ratio of the width of the joint portion to the sum of the thicknesses of the metal plate, the cell main body portion, and the deformation suppression layer is 0.05 or more and 1.0 or less.
10. The electrochemical cell of claim 1.
A flow path member for forming a gas flow path between the metal plate and the flow path member is further provided.
The deformation suppression layer is made of an insulating material.
10. The electrochemical cell of claim 1.
The deformation suppression layer is made of a conductive material,
A conductive portion electrically connecting the deformation suppression layer and the electrode layer is disposed in the communication hole.
10. The electrochemical cell of claim 1.

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