Flow path structure, and electrochemical cell

Abstract

The flow path structure includes a first substrate, a second substrate, and a spacer. The first substrate has a gas permeation portion. The gas permeation portion is a portion that allows gas to permeate. The second substrate has a convex portion. The convex portion protrudes toward the first substrate. The spacer is disposed between the convex portion and the first substrate. The spacer is configured to form a gap between the convex portion and the first substrate.

Description

Technical Field

[0001] The present invention relates to a flow path structure and an electrochemical cell.

Background Art

[0002] In an electrochemical cell such as an electrolytic cell or a fuel cell, a structure in which a cell main body is supported by a metal substrate is known. For example, in the electrochemical cell disclosed in Patent Document 1, an electrode layer, an electrolyte layer, and a counter electrode layer are laminated in this order on a metal substrate. The metal substrate has a plurality of through holes for supplying a raw material gas to the electrode layer.

[0003] Further, the electrochemical cell has an interconnector that forms a flow path for the raw material gas. The interconnector has a plurality of convex portions that protrude toward the metal substrate side. Each convex portion is configured to contact the metal substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the electrochemical cell having the interconnector as described above, there may be a problem that the performance of the electrochemical cell deteriorates because the convex portion of the interconnector blocks some of the plurality of through holes of the metal substrate.

[0006] Therefore, an object of the present invention is to suppress a decrease in the performance of an electrochemical cell.

Means for Solving the Problems

[0007] The flow path structure according to the first aspect includes a first substrate, a second substrate, and a spacer. The first substrate has a gas permeation portion. The gas permeation portion is a portion that allows gas to permeate. The second substrate has a convex portion. The convex portion protrudes toward the first substrate. The spacer is disposed between the convex portion and the first substrate. The spacer is configured to form a gap between the convex portion and the first substrate.

[0008] According to this configuration, since the spacer forms a gap between the convex portion and the first substrate, it is possible to prevent the convex portion from blocking the through hole. As a result, a decrease in the performance of the electrochemical cell can be suppressed.

[0009] The flow path structure according to the second aspect is configured as follows in the flow path structure according to the first aspect. The first substrate has a through hole as the gas permeation portion.

[0010] The flow path structure according to the third aspect is configured as follows in the flow path structure according to the second aspect. The spacer is disposed along the through hole.

[0011] The flow path structure according to the fourth aspect is configured as follows in the flow path structure according to the third aspect. The spacer extends in a ring shape and has a non-uniform height.

[0012] The flow path structure according to the fifth aspect is configured as follows in the flow path structure according to the third or fourth aspect. The spacer extends intermittently in a ring shape.

[0013] The flow path structure according to the sixth aspect is configured as follows in the flow path structure according to any one of the first to fifth aspects. The spacer is fixed to the first substrate.

[0014] The flow path structure according to the seventh aspect is configured as follows in the flow path structure according to any one of the first to sixth aspects. The spacer is fixed to the convex portion.

[0015] The flow channel structure according to the eighth aspect is configured as follows in the flow channel structure according to any one of the first to seventh aspects. The spacer is made of a material containing an oxide.

[0016] The flow channel structure according to the ninth aspect is configured as follows in the flow channel structure according to any one of the first to eighth aspects. The spacer is made of a material containing a metal.

[0017] The electrochemical cell according to the tenth aspect includes the flow channel structure according to any one of the first to ninth aspects and a cell main body. The cell main body is disposed on the first substrate. The cell main body has an anode, an electrolyte, and a cathode.

Advantages of the Invention

[0018] According to the present invention, a decrease in the performance of the electrochemical cell can be suppressed.

Brief Description of the Drawings

[0019]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0020] Hereinafter, the electrolytic cell 100 (an example of an electrochemical cell) according to this embodiment will be described with reference to the drawings. In this embodiment, a solid oxide electrolytic cell (SOEC) will be used as an example of the electrolytic cell 100 for description. FIG. 1 is a plan view of the electrolytic cell 100. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1.

[0021] <Electrolytic cell> As shown in FIGS. 1 and 2, the electrolytic cell 100 (an example of an electrochemical cell) is formed in a plate shape that spreads in the X-axis direction and the Y-axis direction. In this embodiment, when the electrolytic cell 100 is viewed in plan along the Z-axis direction perpendicular to the X-axis direction and the Y-axis direction, it is formed in a rectangle extending in the Y-axis direction. However, the planar shape of the electrolytic cell 100 is not particularly limited, and it may be a polygon other than a rectangle, an ellipse, a circle, or the like. Note that the Z-axis direction means the thickness direction of the electrolytic cell 100, the cell main body 2, and the flow path structure 3.

[0022] As shown in FIGS. 1 and 2, the electrolytic cell 100 includes a cell main body 2 and a flow path structure 3.

[0023] <Cell main body> The cell main body 2 is disposed on the flow path structure 3. The cell main body 2 is supported by a support substrate 31, which will be described later, among the flow path structures 3. The cell main body 2 is disposed on the support substrate 31 so as to cover a plurality of through holes 313, which will be described later. The cell main body 2 has a hydrogen electrode 21 (cathode), an electrolyte 22, a reaction prevention layer 23, and an oxygen electrode 24 (anode).

[0024] The hydrogen electrode 21, the electrolyte 22, the reaction prevention layer 23, and the oxygen electrode 24 are laminated in this order from the side of the flow path structure 3 in the Z-axis direction. The hydrogen electrode 21, the electrolyte 22, and the oxygen electrode 24 are essential components, and the reaction prevention layer 23 is an optional component.

[0025] <Hydrogen electrode> The hydrogen electrode 21 is disposed on the first main surface 311 of the support substrate 31. The raw material gas is supplied to the hydrogen electrode 21 from each through-hole 313 of the support substrate 31. The raw material gas contains at least water vapor (H2O). The hydrogen electrode 21 generates H2 accompanying the electrolysis reaction.

[0026] When the raw material gas contains only H2O, the hydrogen electrode 21 generates H2 from the raw material gas according to the electrochemical reaction of water electrolysis represented by the following formula (1).

[0027] · Hydrogen electrode 21: H2O + 2e - → H2 + O 2- ··· (1) When the raw material gas contains CO2 in addition to H2O, the hydrogen electrode 21 generates H2, CO and O from the raw material gas according to the electrochemical reactions of co-electrolysis represented by the following formulas (2), (3) and (4). 2- is generated.

[0028] · Hydrogen electrode 21: CO2 + H2O + 4e - → CO + H2 + 2O 2- ··· (2) · Electrochemical reaction of H2O: H2O + 2e - → H2 + O 2- ··· (3) · Electrochemical reaction of CO2: CO2 + 2e - → CO + O 2- ··· (4)

[0029] The H2 generated at the hydrogen electrode 21 flows out into the internal space 30 described later from each through-hole 313 of the support substrate 31.

[0030] The hydrogen electrode 21 is a porous body having electron conductivity. The hydrogen electrode 21 contains nickel (Ni). In the case of co-electrolysis, Ni functions as an electron conductive material and also functions as a thermal catalyst that promotes the thermal reaction between the generated H2 and CO2 contained in the raw material gas to maintain a gas composition suitable for methanation or Fischer-Tropsch (FT) synthesis. The Ni contained in the hydrogen electrode 21 basically exists in the state of metallic Ni during the operation of the electrolytic cell 100, but a part thereof may exist in the state of nickel oxide (NiO).

[0031] The hydrogen electrode 21 may contain an ion-conductive material. Examples of the ion-conductive material include yttria-stabilized zirconia (YSZ), calcia-stabilized zirconia (CSZ), scandia-stabilized zirconia (ScSZ), gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), (La,Sr)(Cr,Mn)O3, (La,Sr)TiO3, Sr2(Fe,Mo)2O6, (La,Sr)VO3, (La,Sr)FeO3, and a mixed material obtained by combining two or more of these.

[0032] The thickness of the hydrogen electrode 21 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less. The value of the coefficient of thermal expansion of the hydrogen electrode 21 is not particularly limited, but can be, for example, 12×10 ―6 / °C or more and 20×10 -6 / °C or less.

[0033] The method for forming the hydrogen electrode 21 is not particularly limited, and a firing method, a spray coating method (such as a thermal spraying method, an aerosol deposition method, an aerosol gas deposition method, a powder jet deposition method, a particle jet deposition method, a cold spray method, etc.), a PVD method (such as a sputtering method, a pulsed laser deposition method, etc.), a CVD method, etc. can be used.

[0034] <Electrolyte> The electrolyte 22 is formed on the hydrogen electrode 21. The electrolyte 22 is disposed between the hydrogen electrode 21 and the oxygen electrode 24. In the present embodiment, the electrolyte 22 is sandwiched between the hydrogen electrode 21 and the reaction prevention layer 23 and is connected to both of them.

[0035] The electrolyte 22 covers the hydrogen electrode 21 and covers the region of the first main surface 311 of the support substrate 31 that is exposed from the hydrogen electrode 21.

[0036] The electrolyte 22 is a dense body having oxide ion conductivity. The electrolyte 22 is O generated at the hydrogen electrode 21 2-It is transmitted to the oxygen electrode 24 side. The electrolyte 22 is composed of an oxide ion conductive material. The electrolyte 22 can be composed of, for example, YSZ, GDC, ScSZ, SDC, LSGM (lanthanum gallate), etc., and YSZ is particularly preferred.

[0037] The thickness of the electrolyte 22 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less. The value of the thermal expansion coefficient of the electrolyte 22 is not particularly limited, but can be, for example, 10×10 ―6 / °C or more and 12×10 ―6 / °C or less.

[0038] The method for forming the electrolyte 22 is not particularly limited, and firing methods, spray coating methods, PVD methods, CVD methods, etc. can be used.

[0039] <Reaction prevention layer> The reaction prevention layer 23 is disposed between the electrolyte 22 and the oxygen electrode 24. The reaction prevention layer 23 is disposed on the opposite side of the hydrogen electrode 21 with respect to the electrolyte 22. The reaction prevention layer 23 suppresses the formation of a layer with a large electrical resistance due to the reaction of the constituent elements of the electrolyte 22 with the constituent elements of the oxygen electrode 24.

[0040] The reaction prevention layer 23 is composed of an oxide ion conductive material. The reaction prevention layer 23 can be composed of GDC, SDC, etc.

[0041] The porosity of the reaction prevention layer 23 is not particularly limited, but can be, for example, 0.1% or more and 50% or less. The thickness of the reaction prevention layer 23 is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less.

[0042] The method for forming the reaction prevention layer 23 is not particularly limited, and firing methods, spray coating methods, PVD methods, CVD methods, etc. can be used.

[0043] <Oxygen electrode> The oxygen electrode 24 is disposed on the side opposite to the hydrogen electrode 21 with respect to the electrolyte 22. In the present embodiment, since the reaction prevention layer 23 is disposed between the electrolyte 22 and the oxygen electrode 24, the oxygen electrode 24 is connected to the reaction prevention layer 23. When the reaction prevention layer 23 is not disposed between the electrolyte 22 and the oxygen electrode 24, the oxygen electrode 24 is connected to the electrolyte 22.

[0044] The oxygen electrode 24 generates O2 from O transmitted from the hydrogen electrode 21 through the electrolyte 22 according to the chemical reaction of the following formula (5). 2- to generate O2.

[0045] · Oxygen electrode 24: 2O 2- → O2 + 4e - ··· (5)

[0046] The oxygen electrode 24 is a porous body having oxide ion conductivity and electron conductivity. The oxygen electrode 24 can be composed of a composite material of one or more of, for example, (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).

[0047] The porosity of the oxygen electrode 24 is not particularly limited, but can be, for example, 20% or more and 60% or less. The thickness of the oxygen electrode 24 is not particularly limited, but can be, for example, 1 μm or more and 100 μm or less.

[0048] The method for forming the oxygen electrode 24 is not particularly limited, and a firing method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0049] <Flow channel structure> The flow path structure 3 is configured such that the raw material gas supplied to the cell main body 2 and the reducing gas (H2 in this embodiment) generated at the hydrogen electrode 21 flow therethrough. Specifically, the flow path structure 3 has an internal space 30. The raw material gas and the reducing gas flow within the internal space 30 of the flow path structure 3. The flow path structure 3 includes a support substrate 31 (an example of a first substrate), an interconnector 32 (an example of a second substrate), and a plurality of spacers 33.

[0050] <Support substrate> As shown in FIG. 2, the support substrate 31 supports the cell main body 2. In this embodiment, the support substrate 31 is formed in a plate shape. The support substrate 31 only needs to be able to support the cell main body 2, and its thickness is not particularly limited, but can be, for example, 0.1 mm or more and 2.0 mm or less.

[0051] The support substrate 31 has a first main surface 311, a second main surface 312, and a plurality of through holes 313 (an example of a gas permeation portion). In this embodiment, the first main surface 311 is the upper surface of the support substrate 31, and the second main surface 312 is the lower surface of the support substrate 31. The first main surface 311 faces the cell main body 2. The second main surface 312 faces the interconnector 32.

[0052] Each through hole 313 is configured to allow gas to permeate. Each through hole 313 penetrates the support substrate 31 from the first main surface 311 to the second main surface 312. Each through hole 313 opens to each of the first main surface 311 and the second main surface 312. Therefore, gas permeates through the support substrate 31 via each through hole 313.

[0053] Each through hole 313 is covered by the cell main body 2. Specifically, the opening on the first main surface 311 side of each through hole 313 is covered by the hydrogen electrode 21. The opening on the second main surface 312 side of each through hole 313 is connected to the internal space 30.

[0054] Each through hole 313 can be formed by machining (e.g., punching), laser processing, or chemical processing (e.g., etching).

[0055] In this embodiment, each through hole 313 is formed linearly along the Z-axis direction. However, each through hole 313 may be inclined with respect to the Z-axis direction or may not be linear. Also, the through holes 313 may be connected to each other.

[0056] The support substrate 31 is made of an alloy containing Cr (chromium). Examples of such alloys include Fe-Cr alloy steels (such as stainless steel) and Ni-Cr alloy steels. The Cr content in the support substrate 31 is not particularly limited, but can be 4 mass% or more and 30 mass% or less.

[0057] The support substrate 31 may contain Ti (titanium) or Zr (zirconium). The Ti content in the support substrate 31 is not particularly limited, but can be 0.01 mol% or more and 1.0 mol% or less. The Zr content in the support substrate 31 is not particularly limited, but can be 0.01 mol% or more and 0.4 mol% or less. The support substrate 31 may contain Ti as TiO2 (titania) or may contain Zr as ZrO2 (zirconia).

[0058] <Interconnector> The interconnector 32 is disposed on the second main surface 312 side of the support substrate 31. The interconnector 32 is a member for electrically connecting the electrolytic cell 100 to an external power source or another electrolytic cell.

[0059] The interconnector 32 is formed in a plate shape. The interconnector 32 is fixed to the support substrate 31 at the outer peripheral portion. The interconnector 32 is fixed to the support substrate 31 by, for example, welding or adhesion.

[0060] The thickness of the interconnector 32 is not particularly limited, and for example, it can be 0.1 mm or more and 2.0 mm or less. The outer peripheral portion of the interconnector 32 protrudes toward the support substrate 31 side. The outer periphery of the internal space 30 is defined by the outer peripheral portion of the interconnector 32. Note that the outer peripheral portion of the interconnector 32 may be a separate member from the interconnector 32. The interconnector 32 has a plurality of first convex portions 321 (an example of a convex portion) and a plurality of second convex portions 322.

[0061] Each first convex portion 321 protrudes toward the support substrate 31. Each first convex portion 321 is disposed within the internal space 30. The height of each first convex portion 321 is not particularly limited, and for example, it can be 0.1 mm or more and 2.0 mm or less.

[0062] Each second convex portion 322 protrudes on the side opposite to the first convex portion 321. The height of each second convex portion 322 is not particularly limited, and for example, it can be 0.1 mm or more and 2.0 mm or less.

[0063] FIG. 3 is a plan view of the interconnector 32. In FIG. 3, for ease of illustration, only the first convex portions 321 are shown, and the recesses that appear as the back surfaces of the second convex portions 322 are not shown. As shown in FIG. 3, the first convex portions 321 are arranged at intervals from each other. Specifically, the first convex portions 321 are arranged in a staggered pattern. Each first convex portion 321 can be formed by pressing, cutting, or etching the interconnector 32. Note that each second convex portion 322 is configured in the same manner.

[0064] The first convex portion 321 is larger than the through hole 313 in a plan view. Therefore, in a plan view, a plurality of through holes 313 overlap with the first convex portion 321.

[0065] The interconnector 32 has a supply hole 323 and a discharge hole 324. The supply hole 323 and the discharge hole 324 communicate with the internal space 30. The supply hole 323 penetrates the interconnector 32 in the Z-axis direction. The raw material gas supplied from an external gas supply source to the electrolytic cell 100 flows in the supply hole 323 in the Z-axis direction. The raw material gas is supplied into the internal space 30 through the supply hole 323.

[0066] The discharge hole 324 penetrates the interconnector 32 in the Z-axis direction. H2 generated at the hydrogen electrode 21 and flowing in the internal space 30 is discharged to the outside through the discharge hole 324 and recovered.

[0067] The interconnector 32 is made of an alloy containing Cr. Examples of such alloys include Fe-Cr alloy steel and Ni-Cr alloy steel. The Cr content in the interconnector 32 is not particularly limited, but can be 4 mass% or more and 30 mass% or less. The composition of the interconnector 32 may be the same as or different from that of the support substrate 31.

[0068] <Spacer> FIG. 4 is an enlarged cross-sectional view, and FIG. 5 is a plan view of the support substrate 31 as viewed from the second main surface 312 side. As shown in FIGS. 4 and 5, the spacer 33 is disposed between the first convex portion 321 and the support substrate 31. The spacer 33 forms a gap G between the first convex portion 321 and the support substrate 31. The gap G between the first convex portion 321 and the support substrate 31 formed by the spacer 33 is not particularly limited, but is, for example, about 1 μm or more and 300 μm or less.

[0069] The spacer 33 is disposed along the through hole 313. Specifically, the spacer 33 is disposed along the opening edge of the through hole 313 on the second main surface 312 side. The spacer 33 extends annularly. In a view in the Z-axis direction, the spacer 33 is circular.

[0070] The spacer 33 is fixed to the second main surface 312 of the support substrate 31. Specifically, the spacer 33 is formed on the support substrate 31. That is, no gap is formed between the spacer 33 and the support substrate 31.

[0071] The spacer 33 has a non-uniform height. For example, the height of the spacer 33 varies along the circumferential direction. The spacer 33 has a portion with a lower height than other portions. Note that the height of the spacer 33 is the dimension in the Z-axis direction. The portion with the lower height of the spacer 33 is not in contact with the first convex portion 321. Through this portion where the spacer 33 is not in contact with the first convex portion 321, the through hole 313 and the gap G communicate with each other. That is, the spacer 33 has a communication means 331 that communicates the through hole 313 and the gap G. The communication means 331 is configured by not bringing a part of the spacer 33 into contact with the first convex portion 321.

[0072] A part of the spacer 33 is in contact with the first convex portion 321. The spacer 33 may or may not be fixed to the first convex portion 321 at the portion in contact with the first convex portion 321.

[0073] The spacer 33 is made of a material having a higher Young's modulus than the support substrate 31. The spacer 33 is made of a material containing an oxide. Specifically, the spacer 33 is made of a material consisting only of an oxide. For example, the spacer 33 is made of oxide ceramics. More specifically, the spacer 33 can be made of Cr2O3, (Mn,Cr)3O4, (Mn,Cr,Fe)3O4, (Cr,Fe)2O3, Fe2O3, Fe3O4, Al2O3, ZrO2, or CeO2, etc.

[0074] The spacer 33 may be composed of a material containing metal. The spacer 33 may contain an oxide in addition to the metal. Examples of the metal contained in the spacer 33 include Fe, Co, Ni, or Cu. Examples of the oxide contained in the spacer 33 include Cr2O3, (Mn,Cr)3O4, (Mn,Cr,Fe)3O4, (Cr,Fe)2O3, Fe3O4, Al2O3, ZrO2, and CeO2.

[0075] Among the plurality of spacers 33, all of the spacers 33 may be composed of a material containing an oxide, or all of the spacers 33 may be composed of a material containing metal. Further, the spacers 33 composed of a material containing an oxide and the spacers 33 composed of a material containing metal may be mixed.

[0076] The spacer 33 can be formed by applying a paste containing the above material onto the opening edge of the through hole 313 on the second main surface 312 of the support substrate 31 by a precision nozzle dispenser and firing the paste.

[0077] [Modification Example] As described above, the embodiments of the present invention have been described, but the present invention is not limited to these, and various modifications are possible without departing from the spirit of the present invention.

[0078] (a) In the above embodiment, the spacer 33 extends annularly, but the shape of the spacer is not limited to this. For example, the spacer 33 may have a block shape or other shape as long as it is disposed between the first convex portion 321 and the support substrate 31.

[0079] (b) The spacer 33 may have a uniform height. That is, the spacer 33 may be in contact with the first convex portion 321 as a whole in the circumferential direction. In this case, the communication means of the spacer 33 may be constituted by forming the spacer 33 of a material through which gas can permeate, or the communication means may be constituted by forming a through hole through which gas permeates in the spacer 33.

[0080] (c) In the above embodiment, the spacer 33 extends continuously in an annular shape, but the shape of the spacer 33 is not limited to this. For example, as shown in FIG. 6, the spacer 33 may extend intermittently in an annular shape. In this case, the interrupted portion of the spacer 33 serves as the communication means.

[0081] (d) In the above embodiment, the spacer 33 is arranged to contact the opening edge of the through hole 313, but the arrangement of the spacer 33 is not limited to this. As shown in FIG. 7, the spacer 33 may be arranged at a distance from the opening edge of the through hole 313.

[0082] (e) In the above embodiment, the first convex portion 321 is circular in plan view, but the shape of the first convex portion 321 is not limited to this. For example, as shown in FIG. 8, the first convex portion 321 may be rectangular in plan view. The first convex portion 321 may extend in the Y-axis direction or in the X-axis direction.

[0083] (f) In the above embodiment, the spacer 33 is constituted by a separate member from the support substrate 31, but the constitution of the spacer 33 is not limited to this. For example, the spacer 33 may be integrally constituted by the support substrate 31 and one member, or may be integrally formed by the first convex portion 321 and one member.

[0084] ( g ) In the above embodiment, an electrolytic cell was described as an example of the electrochemical cell, but the electrochemical cell is not limited to the electrolytic cell. An 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 in order to convert electrical energy into chemical energy, and an element for converting chemical energy into electrical energy. Therefore, the electrochemical cell includes, for example, a fuel cell using oxide ions or protons as carriers.

Explanation of Reference Numerals

[0085] 2: Cell main body 3: Flow path structure 31: Support substrate 313: Through hole 32: Interconnector 321: First convex portion 33: Spacer 100: Electrolytic cell

Claims

1. a first substrate having a gas permeable portion that allows gas to pass therethrough; a second substrate having a protrusion protruding toward the first substrate; a spacer disposed between the protrusion and the first substrate and configured to form a gap between the protrusion and the first substrate; Equipped with The gas permeable portion is a through hole formed linearly. Flow path structure.

2. The spacer is disposed along the through hole. The flow path structure according to claim 1 .

3. The spacer extends annularly and has a non-uniform height. The flow path structure according to claim 2 .

4. The spacer extends discontinuously in an annular shape. The flow path structure according to claim 2 .

5. the spacer is fixed to the first substrate; The flow path structure according to claim 1 .

6. The spacer is fixed to the protrusion. The flow path structure according to claim 5 .

7. the spacer is made of a material containing an oxide; The flow path structure according to claim 1 .

8. the spacer is made of a material including a metal; The flow path structure according to claim 1 .

9. The flow path structure according to claim 1 ; a cell main body disposed on the first substrate; Equipped with Electrochemical cell.

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