Flow path structure and electrochemical cell

Abstract

A flow path structure according to the present invention comprises a first substrate, a second substrate, and a spacer. The first substrate has a gas permeation section. The gas permeation section is a section that allows the permeation of a gas. The second substrate has a protrusion. The protrusion protrudes towards the first substrate. The spacer is positioned between the protrusion and the first substrate. The spacer is configured so as to form a space between the protrusion and the first substrate.

Description

Flow path structure and electrochemical cell

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

[0002] In electrochemical cells such as electrolysis cells or fuel cells, a structure in which a cell body is supported by a metal substrate is known. For example, an electrochemical cell disclosed in Patent Document 1 has an electrode layer, an electrolyte layer, and a counter electrode layer stacked 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] The electrochemical cell also has an interconnector that forms a flow path for the source gas. The interconnector has a plurality of protrusions that protrude toward the metal substrate. Each protrusion is configured to come into contact with the metal substrate.

[0004] International Publication No. 2018 / 181926

[0005] In an electrochemical cell having an interconnector as described above, the protrusions of the interconnector block some of the through holes of the metal substrate, which can cause a problem of reduced performance of the electrochemical cell.

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

[0007] The flow path structure according to a first aspect includes a first substrate, a second substrate, and a spacer. The first substrate has a gas permeable portion. The gas permeable portion is a portion that allows gas to pass through. 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, the spacer forms a gap between the protrusion and the first substrate, preventing the protrusion from blocking the through-hole, thereby suppressing a decrease in performance of the electrochemical cell.

[0009] The flow path structure according to the second aspect is the flow path structure according to the first aspect, and is configured as follows: The first substrate has through holes as gas permeable portions.

[0010] The flow path structure according to the third aspect is the flow path structure according to the second aspect, and is configured as follows: The spacer is arranged along the through hole.

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

[0012] A flow path structure according to a fifth aspect is the flow path structure according to the third or fourth aspect, and is configured as follows: The spacer extends discontinuously in an annular shape.

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

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

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

[0016] A duct structure according to a ninth aspect is the duct structure according to any one of the first to eighth aspects, configured as follows: The spacer is made of a material containing metal.

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

[0018] According to the present invention, it is possible to suppress the deterioration of the performance of the electrochemical cell.

[0019] 1. A plan view of an electrolysis cell. A cross-sectional view taken along line II-II in FIG. 1. A plan view of an interconnector. An enlarged cross-sectional view of an electrolysis cell. A plan view of a spacer. A plan view of a spacer according to a modified example. A plan view of a spacer according to a modified example. A plan view of an interconnector according to a modified example.

[0020] An electrolytic cell 100 (an example of an electrochemical cell) according to this embodiment will be described below 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. FIG. 1 is a plan view of the electrolytic cell 100. FIG. 2 is a cross-sectional view taken along line II-II in FIG. 1.

[0021] 1 and 2 , the electrolytic cell 100 (an example of an electrochemical cell) is formed in the shape of a plate extending in the X-axis and Y-axis directions. In this embodiment, the electrolytic cell 100 is formed in a rectangular shape extending in the Y-axis direction when viewed in a plan view along the Z-axis direction, which is perpendicular to the X-axis and Y-axis directions. However, the planar shape of the electrolytic cell 100 is not particularly limited, and may be a polygon other than a rectangle, an ellipse, a circle, or the like. The Z-axis direction refers to 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 electrolysis 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 (described later) of the flow path structure 3. The cell main body 2 is disposed on the support substrate 31 so as to cover a plurality of through-holes 313 (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 stacked in this order in the Z-axis direction from the flow path structure 3 side. The hydrogen electrode 21, the electrolyte 22, and the oxygen electrode 24 are essential components, while 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. A source gas is supplied to the hydrogen electrode 21 through each through-hole 313 of the support substrate 31. The source gas contains at least water vapor (H ２ The hydrogen electrode 21 contains H ２ Generate.

[0026] The raw material gas is H２ When the raw material gas contains only O, the hydrogen electrode 21 converts H into H according to the electrochemical reaction of water electrolysis shown in the following formula (1): ２ Generate.

[0027] Hydrogen electrode 21: H ２ O + 2e － →H ２ +O ２－ ... (1) The raw material gas is H ２ O plus CO ２ In this case, the hydrogen electrode 21 converts the raw material gas into H according to the electrochemical reactions of co-electrolysis shown in the following formulas (2), (3), and (4). ２ , CO and O ２－ Generate.

[0028] Hydrogen electrode 21: CO ２ +H ２ O+4e － →CO+H ２ +20 ２－ ... (2) H ２ Electrochemical reaction of O: H ２ O + 2e － →H ２ +O ２－ ... (3) CO ２ Electrochemical reaction of: CO ２ +2e － →CO+O ２－ ...(4)

[0029] H generated at the hydrogen electrode 21 ２ The flow of the heat from the support substrate 31 flows out from each through-hole 313 into the internal space 30 described later.

[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 conductor and also functions as a conductor for the generated H ２ and CO contained in the raw material gas ２ It also functions as a thermal catalyst that promotes the thermal reaction with HCl and maintains an appropriate gas composition for methanation, Fischer-Tropsch (FT) synthesis, etc. The Ni contained in the hydrogen electrode 21 is basically present in the form of metallic Ni during operation of the electrolysis cell 100, but a portion of it may also be present in the form of nickel oxide (NiO).

[0031] The hydrogen electrode 21 may contain an ion-conductive material, such as yttria-stabilized zirconia (YSZ), calcia-stabilized zirconia (CSZ), scandia-stabilized zirconia (ScSZ), gadolinium-doped ceria (GDC), samarium-doped ceria (SDC), (La, Sr)(Cr, Mn)O, or the like. ３ , (La,Sr)TiO ３ , Sr ２ (Fe, Mo) ２ O ６ , (La, Sr)VO ３ , (La,Sr)FeO ３ and mixed materials of two or more of these.

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

[0033] The method for forming the hydrogen electrode 21 is not particularly limited, and may be 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, or a cold spray method), a PVD method (such as a sputtering method or a pulsed laser deposition method), or a CVD method.

[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 this embodiment, the electrolyte 22 is sandwiched between the hydrogen electrode 21 and the reaction prevention layer 23 and connected to both of them.

[0035] The electrolyte 22 covers the hydrogen electrode 21 and also 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. ２－The electrolyte 22 is made of an oxide ion conductive material, such as YSZ, GDC, ScSZ, SDC, or LSGM (lanthanum gallate), with YSZ being particularly suitable.

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

[0038] The method for forming the electrolyte 22 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like 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 electrolyte 22 from the hydrogen electrode 21. The reaction prevention layer 23 prevents the constituent elements of the electrolyte 22 from reacting with the constituent elements of the oxygen electrode 24 to form a layer with high electrical resistance.

[0040] The reaction prevention layer 23 is made of an oxide ion conductive material, such as GDC or SDC.

[0041] The porosity of the reaction prevention layer 23 is not particularly limited, but may be, for example, 0.1% to 50%. The thickness of the reaction prevention layer 23 is not particularly limited, but may be, for example, 1 μm to 50 μm.

[0042] The method for forming the reaction prevention layer 23 is not particularly limited, and may be a baking method, a spray coating method, a PVD method, a CVD method, or the like.

[0043] <Oxygen electrode> The oxygen electrode 24 is disposed on the opposite side of the electrolyte 22 from the hydrogen electrode 21. In this embodiment, the reaction prevention layer 23 is disposed between the electrolyte 22 and the oxygen electrode 24, and therefore the oxygen electrode 24 is connected to the reaction prevention layer 23. If 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 converts O 2 transferred from the hydrogen electrode 21 through the electrolyte 22 in accordance with the chemical reaction of the following formula (5): ２－ From O ２ Generate.

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

[0046] The oxygen electrode 24 is a porous body having oxide ion conductivity and electron conductivity. The oxygen electrode 24 is made of, for example, (La, Sr)(Co, Fe)O ３ , (La,Sr)FeO ３ , La(Ni,Fe)O ３ , (La,Sr)CoO ３ , and (Sm,Sr)CoO ３ and an oxide ion conductive material (such as GDC).

[0047] The porosity of the oxygen electrode 24 is not particularly limited, but may be, for example, 20% to 60%. The thickness of the oxygen electrode 24 is not particularly limited, but may be, for example, 1 μm to 100 μm.

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

[0049] <Flow Channel Structure> The flow channel structure 3 is a gas supplying structure for supplying a raw material gas to the cell main body 2 and a reducing gas (H ２ ) flows through the flow channel structure 3. Specifically, the flow channel structure 3 has an internal space 30. The raw material gas and the reducing gas flow through the internal space 30 of the flow channel structure 3. The flow channel structure 3 has 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] 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 permeable 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 pass through. 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 the first main surface 311 and the second main surface 312, respectively. Therefore, gas passes 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 of each through-hole 313 on the first main surface 311 side is covered by the hydrogen electrode 21. The opening of each through-hole 313 on the second main surface 312 side is connected to the internal space 30.

[0054] Each through-hole 313 can be formed by mechanical processing (for example, punching), laser processing, chemical processing (for example, etching), or the like.

[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. Furthermore, 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 steel (stainless steel, etc.) and Ni—Cr alloy steel. The Cr content in the support substrate 31 is not particularly limited, but can be set to 4% by mass or more and 30% by 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 set to 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 set to 0.01 mol % or more and 0.4 mol % or less. The support substrate 31 may contain Ti in the form of TiO ２ (titania), or Zr may be contained as ZrO ２ It may be contained as (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, and the outer periphery of the interconnector 32 is fixed to the support substrate 31. The interconnector 32 is fixed to the support substrate 31 by, for example, welding or adhesive.

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

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

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

[0063] FIG. 3 is a plan view of the interconnector 32. Note that, for ease of illustration, FIG. 3 only shows the first convex portions 321, and does not show the concave portions that appear as the back surfaces of the second convex portions 322. As shown in FIG. 3, the first convex portions 321 are arranged at intervals from one another. Specifically, the first convex portions 321 are arranged in a staggered pattern. The first convex portions 321 can be formed by subjecting the interconnector 32 to press processing, cutting processing, etching processing, or the like. Note that the second convex portions 322 are also configured in the same manner.

[0064] In plan view, the first convex portions 321 are larger than the through holes 313. Therefore, in plan view, the plurality of through holes 313 overlap with the first convex portions 321.

[0065] The interconnector 32 has a supply hole 323 and a discharge hole 324. The supply hole 323 and the discharge hole 324 are in communication with the internal space 30. The supply hole 323 penetrates the interconnector 32 in the Z-axis direction. A raw material gas supplied to the electrolysis cell 100 from an external gas supply source flows through 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. ２ is discharged to the outside through the discharge hole 324 and collected.

[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 set to 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, approximately 1 µm or more and 300 µm or less.

[0069] The spacer 33 is arranged along the through hole 313. More specifically, the spacer 33 is arranged along the opening edge of the through hole 313 on the second main surface 312 side. The spacer 33 extends in an annular shape. When viewed 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. More specifically, the spacer 33 is formed on the support substrate 31. In other words, 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 that is lower in height than other portions. The height of the spacer 33 is the dimension in the Z-axis direction. The lower portion of the spacer 33 is not in contact with the first convex portion 321. The through hole 313 and the gap G are in communication with each other via the portion of the spacer 33 that is not in contact with the first convex portion 321. In other words, the spacer 33 has communication means 331 that communicates the through hole 313 and the gap G. The communication means 331 is configured by not making a portion of the spacer 33 in contact with the first convex portion 321.

[0072] A part of the spacer 33 is in contact with the first convex portion 321. The part of the spacer 33 that is in contact with the first convex portion 321 may or may not be fixed to 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. More specifically, the spacer 33 is made of a material consisting of only an oxide. For example, the spacer 33 is made of an oxide ceramic. More specifically, the spacer 33 is made of a material containing Cr ２ O ３ , (Mn, Cr) ３ O ４ , (Mn, Cr, Fe) ３ O ４ , (Cr, Fe) ２ O ３ , Fe ２ O ３ , Fe ３ O ４ , Al ２ O ３ , ZrO ２ , or CeO ２ It can be configured by the following.

[0074] The spacer 33 may be made of a material containing a 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, and Cu. Examples of the oxide contained in the spacer 33 include Cr. ２ O ３ , (Mn, Cr) ３ O ４ , (Mn, Cr, Fe) ３ O ４ , (Cr, Fe) ２ O ３ , Fe ３ O ４ , Al ２ O ３ , ZrO ２ , and CeO ２ Examples include:

[0075] All of the spacers 33 may be made of a material containing an oxide, or all of the spacers 33 may be made of a material containing a metal. Also, spacers 33 made of a material containing an oxide and spacers 33 made of a material containing a metal may be mixed.

[0076] The spacers 33 can be formed by applying a paste containing the above material along the opening edges of the through holes 313 on the second main surface 312 of the support substrate 31 using a precision nozzle dispenser, and then firing the paste.

[0077] [Modifications] 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.

[0078] (a) In the above embodiment, the spacer 33 extends in an annular shape, but the shape of the spacer is not limited to this. For example, the spacer 33 may be block-shaped or have another shape as long as it is disposed between the first protrusion 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 protrusion 321 over the entire circumferential direction. In this case, the communication means of the spacer 33 may be configured by forming the spacer 33 from a gas-permeable material, or by forming through-holes in the spacer 33 through which gas can pass.

[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 discontinuously in an annular shape. In this case, the interrupted portions of the spacer 33 serve as the communication means.

[0081] (d) In the above embodiment, the spacer 33 is disposed so as 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 disposed so as to be spaced apart from the opening edge of the through-hole 313.

[0082] (e) In the above embodiment, the first convex portion 321 has a circular shape in a 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 have a rectangular shape in a plan view. The first convex portion 321 may extend in the Y-axis direction or the X-axis direction.

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

[0084] (f) In the above embodiment, an electrolytic cell has been described as an example of an electrochemical cell, but the electrochemical cell is not limited to an electrolytic cell. An electrochemical cell is a general term that refers to 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, electrochemical cells also include, for example, fuel cells that use oxide ions or protons as carriers.

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

Claims

1. A first substrate having a gas permeation part for permeating a gas, a second substrate having a convex part protruding toward the first substrate, and a spacer disposed between the convex part and the first substrate and configured to form a gap between the convex part and the first substrate. A flow path structure comprising:

2. The flow path structure according to claim 1, wherein the first substrate has a through hole as the gas permeation part.

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

4. The flow path structure according to claim 3, wherein the spacer extends annularly and has a non-uniform height.

5. The flow path structure according to claim 3, wherein the spacer extends intermittently annularly.

6. The flow path structure according to claim 1, wherein the spacer is fixed to the first substrate.

7. The flow path structure according to claim 6, wherein the spacer is fixed to the convex part.

8. The flow path structure according to claim 1, wherein the spacer is made of a material containing an oxide.

9. The flow path structure according to claim 1, wherein the spacer is made of a material containing a metal.

10. An electrochemical cell comprising the flow path structure according to claim 1 and a cell body part disposed on the first substrate.

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