Interconnector and electrochemical cell

Abstract

The interconnector has a main body and a plurality of oxide layers. The main body has a first main surface, a second main surface, and a plurality of protrusions. The second main surface faces the opposite side to the first main surface. Each protrusion is formed on the first main surface. Each oxide layer is disposed on a side surface of each protrusion. At least one oxide layer has a thickness distribution that induces warping such that the main body bulges toward the second main surface.

Description

[Technical field]

[0001] The present invention relates to an interconnector and an electrochemical cell. [Background technology]

[0002] An electrochemical cell such as an electrolysis cell or a fuel cell has a cell body, a support substrate, and an interconnector. For example, in the electrochemical cell disclosed in Patent Document 1, a gas flow path is formed by the interconnector and the support substrate, and the cell body is supported on the support substrate. A plurality of electrochemical cells configured in this manner are stacked to form an electrochemical cell stack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 181926 Summary of the Invention [Problem to be solved by the invention]

[0004] When stacking electrochemical cells, if unevenness is formed on the cell main body portion that is located below the interconnector, the interconnector may press against the unevenness, causing the load to be concentrated on the unevenness of the cell main body portion, which may result in damage to the cell main body portion.

[0005] An object of the present invention is to provide an interconnector capable of suppressing damage to a cell main body portion. [Means for solving the problem]

[0006] The interconnector according to the first aspect has a main body and a plurality of oxide layers. The main body has a first main surface, a second main surface, and a plurality of protrusions. The second main surface faces the opposite side to the first main surface. Each protrusion is formed on the first main surface. Each oxide layer is disposed on a side surface of each protrusion. At least one oxide layer has a thickness distribution that induces warping such that the main body bulges toward the second main surface.

[0007] According to this configuration, the interconnector warps so as to bulge toward the second main surface due to the thickness distribution of each oxide layer. Therefore, when stacking electrochemical cells, it is possible to absorb the unevenness on the cell main body portion disposed below the interconnector. As a result, it is possible to suppress the concentration of load on the protruding portion of the cell main body portion, and thus to suppress damage to the cell main body portion.

[0008] The interconnector according to the second aspect is the interconnector according to the first aspect, and is configured as follows. The multiple protrusions are arranged at intervals from one another in the gas flow direction. The multiple protrusions include a first protrusion and a second protrusion. The first protrusion is arranged at the most upstream position in the gas flow direction. The second protrusion is arranged at the most downstream position. Each oxide layer has an upstream portion facing the upstream side and a downstream portion facing the downstream side. The oxide layer arranged on the side surface of the first protrusion has a thickness distribution in which the upstream portion is thinner than the downstream portion.

[0009] The interconnector according to a third aspect is the interconnector according to the second aspect and is configured as follows: The oxide layer disposed on the side surface of the second protrusion has a thickness distribution in which the upstream portion is thicker than the downstream portion.

[0010] The interconnector according to a fourth aspect is the interconnector according to the second or third aspect, and is configured as follows: the multiple protrusions include a third protrusion. The third protrusion is disposed in a central portion between the first protrusion and the second protrusion in the gas flow direction. The difference in thickness between an upstream portion and a downstream portion of the oxide layer disposed on the side surface of the first protrusion is larger than the difference in thickness between the upstream portion and the downstream portion of the oxide layer disposed on the side surface of the third protrusion.

[0011] An interconnector according to a fifth aspect is the interconnector according to any one of the second to fourth aspects, and is configured as follows: the multiple protrusions include a third protrusion. The third protrusion is disposed in a central portion between the first protrusion and the second protrusion in the gas flow direction. The oxide layer disposed on the side surface of the third protrusion is thicker than the oxide layer disposed on the side surface of the first protrusion and is thicker than the oxide layer disposed on the side surface of the second protrusion.

[0012] An interconnector according to a sixth aspect is the interconnector according to the first aspect, and is configured as follows. The multiple protrusions extend in a gas flow direction. The multiple protrusions are arranged at intervals from one another in a first direction perpendicular to the gas flow direction. The multiple protrusions include a first protrusion and a second protrusion. The first protrusion and the second protrusion are arranged outermost in the first direction. Each oxide layer has an outer portion facing outward in the first direction and an inner portion facing inward in the first direction. The oxide layer arranged on the side surface of the first protrusion has a thickness distribution in which the outer portion is thinner than the inner portion.

[0013] The interconnector according to a seventh aspect is the interconnector according to the sixth aspect, and is configured as follows: The oxide layer disposed on the side surface of the second protrusion has a thickness distribution in which the outer portion is thinner than the inner portion.

[0014] An interconnector according to an eighth aspect is the interconnector according to the sixth or seventh aspect, and is configured as follows: the plurality of protrusions include a third protrusion. The third protrusion is disposed in a central portion between the first protrusion and the second protrusion in the first direction. The difference in thickness between an outer portion and an inner portion of the oxide layer disposed on a side surface of the first protrusion is larger than the difference in thickness between the outer portion and the inner portion of the oxide layer disposed on a side surface of the third protrusion.

[0015] An interconnector according to a ninth aspect is the interconnector according to any one of the sixth to eighth aspects, and is configured as follows: the multiple convex portions include a third convex portion. The third convex portion is disposed in a central portion between the first convex portion and the second convex portion in the first direction. The oxide layer disposed on the side surface of the third convex portion is thicker than the oxide layer disposed on the side surface of the first convex portion. The oxide layer disposed on the side surface of the third convex portion is thicker than the oxide layer disposed on the side surface of the second convex portion.

[0016] The interconnector according to a tenth aspect is the interconnector according to any one of the first to ninth aspects, and is configured as follows: the main body is configured of an alloy containing chromium, and each oxide layer contains chromium as a main component.

[0017] An interconnector according to an eleventh aspect is the interconnector according to any one of the first to tenth aspects, and is configured as follows: Each oxide layer has a smaller thermal expansion coefficient than the main body portion.

[0018] An electrochemical cell according to a twelfth aspect includes the interconnector according to any one of the first to eleventh aspects, a support substrate, and a cell body. The support substrate is attached to the interconnector. The cell body is disposed on the support substrate.

[0019] The electrochemical cell according to the thirteenth aspect is configured in the electrochemical cell according to the twelfth aspect as follows: each oxide layer is thinner than the cell main body portion. Effect of the Invention

[0020] According to the present invention, damage to the cell main body can be suppressed. [Brief description of the drawings]

[0021] [Figure 1] FIG. [Diagram 2] Cross-sectional view of line II-II in Figure 1. [Diagram 3] FIG. [Figure 4]FIG. [Diagram 5] Cross-sectional view of line VV in Figure 4. [Figure 6] FIG. [Figure 7] Cross-sectional view taken along line VII-VII in Figure 6. [Figure 8] FIG. [Figure 9] Cross-sectional view taken along line IX-IX in Figure 8. [Figure 10] FIG. 4 is an enlarged cross-sectional view showing the warping direction around a first protrusion of the interconnector. [Figure 11] FIG. 4 is an enlarged cross-sectional view showing the warping direction around a second protrusion of the interconnector. [Figure 12] FIG. 11 is a plan view of an interconnector according to a modified example. [Figure 13] Cross-sectional view taken along line XIII-XIII in Figure 12. [Figure 14] Cross-sectional view taken along line XIV-XIV in Figure 12. [Figure 15] Cross-sectional view taken along line XV-XV in Figure 12. [Figure 16] FIG. 4 is an enlarged cross-sectional view showing the warping direction around a first protrusion of the interconnector. [Figure 17] FIG. 4 is an enlarged cross-sectional view showing the warping direction around a second protrusion of the interconnector. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Hereinafter, an 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. 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.

[0023] <Electrolytic cell> 1 and 2, the electrolytic cell 100 is formed in a plate shape 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 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, the support substrate 3, and the interconnector 4.

[0024] As shown in FIGS. 1 and 2, the electrolysis cell 100 includes a cell main body 2, a support substrate 3, and an interconnector 4.

[0025] <Cell body> The cell body 2 is disposed on a support substrate 3. The cell body 2 is supported by the support substrate 3. The cell body 2 is disposed on the support substrate 3 so as to cover a plurality of through-holes 33 described below. The cell body 2 has a hydrogen electrode 21 (cathode), an electrolyte 22, a reaction prevention layer 23, and an oxygen electrode 24 (anode).

[0026] The hydrogen electrode 21, the electrolyte 22, the reaction prevention layer 23, and the oxygen electrode 24 are laminated in this order in the Z-axis direction from the side of the support substrate 3. 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.

[0027] <Hydrogen electrode> The hydrogen electrode 21 is disposed on the first main surface 31 of the support substrate 3. A source gas is supplied to the hydrogen electrode 21 through each through hole 33 of the support substrate 3. The source gas includes at least water vapor (H 2 O). The hydrogen electrode 21 contains H 2 Generate.

[0028] The raw gas is H 2 When the raw gas contains only O, the hydrogen electrode 21 converts the raw gas into H according to the electrochemical reaction of water electrolysis shown in the following formula (1). 2 Generate.

[0029] Hydrogen electrode 21:H2 O+2e - →H 2 +O 2- (1) The raw gas is H 2 O plus CO 2 In this case, the hydrogen electrode 21 converts the raw 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.

[0030] Hydrogen electrode 21: CO 2 +H 2 O+4e - →CO+H 2 +2O 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)

[0031] H produced at the hydrogen electrode 21 2 The liquid flows out from each through hole 33 of the support substrate 3 into an internal space 30 which will be described later.

[0032] The hydrogen electrode 21 is a porous body having electronic conductivity. The hydrogen electrode 21 contains nickel (Ni). In the case of co-electrolysis, Ni functions as an electronic conductor and also functions as a conductor of the generated H 2 and CO contained in the feed gas 2 It also functions as a thermal catalyst that promotes a thermal reaction with Ni to maintain a gas composition suitable for methanation, Fischer-Tropsch (FT) synthesis, etc. The Ni contained in the hydrogen electrode 21 is basically present in the form of metal Ni during operation of the electrolysis cell 100, but a portion of it may be present in the form of nickel oxide (NiO).

[0033] 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 3 , (La,Sr)TiO 3 , Sr 2 (Fe, Mo) 2 O 6 , (La,Sr)VO 3 , (La,Sr)FeO 3 and mixtures of two or more of these materials.

[0034] 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 20×10 -6 / °C or less.

[0035] The method for forming the hydrogen electrode 21 is not particularly limited, and may be a firing method, a spray coating method (such as thermal spraying, aerosol deposition, aerosol gas deposition, powder jet deposition, particle jet deposition, or cold spray), a PVD method (such as sputtering or pulsed laser deposition), or a CVD method.

[0036] <Electrolytes> 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.

[0037] The electrolyte 22 covers the hydrogen electrode 21 and also covers the area of ​​the first main surface 31 of the support substrate 3 that is exposed from the hydrogen electrode 21 .

[0038] The electrolyte 22 is a dense body having oxide ion conductivity. 2- is transferred to the oxygen electrode 24. The electrolyte 22 is made of an oxide ion conductive material. The electrolyte 22 can be made of, for example, YSZ, GDC, ScSZ, SDC, LSGM (lanthanum gallate), etc., with YSZ being particularly suitable.

[0039] 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 12×10 ―6 / °C or less.

[0040] 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.

[0041] <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 side of the electrolyte 22 opposite to the side on which the hydrogen electrode 21 is disposed. 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.

[0042] The reaction prevention layer 23 is made of an oxide ion conductive material, and may be made of GDC, SDC, or the like.

[0043] 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.

[0044] The method for forming the reaction prevention layer 23 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0045] <Oxygen electrode> The oxygen electrode 24 is disposed on the opposite side to the side on which the hydrogen electrode 21 is disposed with respect to the electrolyte 22. In this 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. 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.

[0046] The oxygen electrode 24 converts the oxygen 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.

[0047] Oxygen pole 24:2O 2- →O 2 +4e - (5)

[0048] The oxygen electrode 24 is a porous body having oxide ion conductivity and electron conductivity. The oxygen electrode 24 is, 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 It can be composed of a composite material of one or more of the above and an oxide ion conductive material (such as GDC).

[0049] 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.

[0050] The method for forming the oxygen electrode 24 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0051] <Support substrate> 2, the support substrate 3 supports the cell main body 2. In this embodiment, the support substrate 3 is formed in a plate shape. The support substrate 3 is only required to support the cell main body 2, and the thickness thereof is not particularly limited, but may be, for example, 0.1 mm or more and 2.0 mm or less.

[0052] In the internal space 30 defined by the support substrate 3 and the interconnector 4, the raw material gas to be supplied to the cell body 2 and the reducing gas (in this embodiment, H 2 ) will be played.

[0053] The support substrate 3 has a first main surface 31, a second main surface 32, and a plurality of through holes 33. In this embodiment, the first main surface 31 is the upper surface of the support substrate 3, and the second main surface 32 is the lower surface of the support substrate 3. The first main surface 31 faces the cell body 2. The second main surface 32 faces the interconnector 4.

[0054] Each through hole 33 is configured to allow gas to pass therethrough. Each through hole 33 penetrates the support substrate 3 from the first main surface 31 to the second main surface 32. Each through hole 33 opens to the first main surface 31 and the second main surface 32, respectively. Therefore, gas passes through the support substrate 3 via each through hole 33.

[0055] Each through hole 33 is covered by the cell main body 2. Specifically, the opening of each through hole 33 on the first main surface 31 side is covered by the hydrogen electrode 21. The opening of each through hole 33 on the second main surface 32 side is connected to the internal space 30.

[0056] Each through hole 33 can be formed by mechanical processing (for example, punching), laser processing, chemical processing (for example, etching), or the like.

[0057] In this embodiment, each through hole 33 is formed linearly along the Z-axis direction. However, each through hole 33 may be inclined with respect to the Z-axis direction, and may not be linear. Furthermore, the through holes 33 may be connected to each other.

[0058] The support substrate 3 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 3 is not particularly limited, but can be set to 4% by mass or more and 30% by mass or less.

[0059] The support substrate 3 may contain Ti (titanium) and / or Zr (zirconium). The Ti content in the support substrate 3 is not particularly limited, but may be set to 0.01 mol % or more and 1.0 mol % or less. The Zr content in the support substrate 3 is not particularly limited, but may be set to 0.01 mol % or more and 0.4 mol % or less. The support substrate 3 may contain Ti in the form of TiO 2 (titania), or ZrO 2 It may be contained as (zirconia).

[0060] <Interconnector> FIG. 3 is a plan view of the interconnector 4. As shown in FIGS. 2 and 3, the interconnector 4 is disposed on the second main surface 32 side of the support substrate 3. The interconnector 4 is a member for electrically connecting the electrolytic cell 100 to an external power source or another electrolytic cell. The interconnector 4 is configured so that the raw material gas and the gas generated at the hydrogen electrode flow into the internal space 30. In the following description, the gas flow direction means the direction from the supply hole 405 toward the exhaust hole 406 described below. Specifically, the Y-axis direction is the gas flow direction. The first direction is a direction perpendicular to the gas flow direction. Specifically, the X-axis direction is the first direction.

[0061] The interconnector 4 is formed in a plate shape. The interconnector 4 is attached to a support substrate 3. The interconnector 4 is fixed to the support substrate 3 at its outer periphery. The interconnector 4 is fixed to the support substrate 3 by, for example, welding or adhesion. The interconnector 4 has a main body 40 and a plurality of oxide layers 41.

[0062] The main body 40 is formed in a plate shape. The thickness of the main body 40 is not particularly limited, but may be, for example, 0.1 mm or more and 2.0 mm or less. The outer periphery of the main body 40 protrudes toward the support substrate 3. The outer periphery of the main body 40 defines the periphery of the internal space 30. The outer periphery of the main body 40 may be a separate member from the main body 40.

[0063] The main body 40 has a first main surface 401, a second main surface 402, a plurality of convex portions 403, a supply hole 405, and a discharge hole 406. The first main surface 401 is a surface facing the support substrate 3. The second main surface 402 is a surface opposite to the first main surface 401. In other words, the second main surface 402 faces in a direction opposite to the direction in which the first main surface 401 faces. In this embodiment, the first main surface 401 is an upper surface of the main body 40, and the second main surface 402 is a lower surface of the main body 40.

[0064] The supply hole 405 and the exhaust hole 406 are in communication with the internal space 30. The supply hole 405 penetrates the interconnector 4 in the Z-axis direction. The raw material gas supplied to the electrolytic cell 100 from an external gas supply source flows through the supply hole 405 in the Z-axis direction. The raw material gas is supplied into the internal space 30 through the supply hole 405.

[0065] The exhaust hole 406 penetrates the interconnector 4 in the Z-axis direction. H 2 is discharged to the outside through the discharge hole 406 and collected.

[0066] Each of the protrusions 403 is formed on the first main surface 401 of the main body 40. Each of the protrusions 403 protrudes toward the support substrate 3. Each of the protrusions 403 is disposed in the internal space 30. The height of each of the protrusions 403 is not particularly limited, but may be, for example, 0.1 mm or more and 2.0 mm or less. Each of the protrusions 403 is columnar or cylindrical.

[0067] 3, the protrusions 403 are arranged at intervals in the gas flow direction. The protrusions 403 are also arranged at intervals in a first direction perpendicular to the gas flow direction. Specifically, the protrusions 403 are arranged in a staggered pattern. The protrusions 403 can be formed by subjecting the interconnector 4 to pressing, cutting, etching, or the like.

[0068] The protruding portion 403 is larger than the through holes 33 in a plan view. Therefore, a plurality of the through holes 33 overlap with the protruding portion 403 in a plan view.

[0069] The plurality of convex portions 403 include a plurality of first convex portions 403a, a plurality of second convex portions 403b, and a plurality of third convex portions 403c. In this embodiment, the plurality of convex portions 403 include five first convex portions 403a, five second convex portions 403b, and four third convex portions 403c.

[0070] Each of the first convex portions 403a is disposed at the most upstream position in the gas flow direction. That is, each of the first convex portions 403a is a convex portion 403 disposed at the upper end of the multiple convex portions 403 in Fig. 3. Each of the first convex portions 403a is arranged in a first direction.

[0071] Each of the second convex portions 403b is disposed at the most downstream position in the gas flow direction. That is, each of the second convex portions 403b is a convex portion 403 disposed at the lower end in Fig. 3 among the multiple convex portions 403. Each of the second convex portions 403b is arranged in the first direction.

[0072] Each of the third convex portions 403c is disposed in the center between each of the first convex portions 403a and each of the second convex portions 403b in the gas flow direction. That is, each of the third convex portions 403c is a convex portion that is closest to the midpoint between the first convex portion 403a and the second convex portion 403b in the gas flow direction among the multiple convex portions 403. Each of the third convex portions 403c is arranged in the first direction.

[0073] As shown in Fig. 2, the main body 40 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 main body 40 is not particularly limited, but can be set to 4% by mass or more and 30% by mass or less. The composition of the main body 40 may be the same as or different from that of the support substrate 3.

[0074] Each oxide layer 41 is formed on the side surface of each protrusion 403. Each oxide layer 41 is formed on the entire side surface of each protrusion 403. That is, each oxide layer 41 is annular in plan view. An oxide layer may be formed on the first main surface 401. In this case, each oxide layer 41 is connected to each other. An oxide layer may be formed on the tip surface of each protrusion 403. An oxide layer is not formed on the outer periphery of the first main surface 401, but an oxide layer may be formed on the outer periphery of the first main surface 401.

[0075] Each oxide layer 41 has a different thermal expansion coefficient from that of the main body portion 40. In this embodiment, the oxide layer 41 has a smaller thermal expansion coefficient than that of the main body portion 40. The oxide layer 41 is made of an oxide containing Cr as a main component (hereinafter, abbreviated as "Cr oxide"). This makes it possible to suppress the diffusion of Cr from the support substrate 3 and the main body portion 40 to the oxide layer 41 during the manufacture or operation of the electrolysis cell 100. Even if Cr diffuses from the support substrate 3 and the main body portion 40 to the oxide layer 41, the effect on the composition of the oxide layer 41 is small, and therefore a decrease in the strength of the oxide layer 41 can also be suppressed.

[0076] In this embodiment, the term "mainly composed of Cr" means that the Cr content is the highest among the metal elements when the composition of the Cr oxide constituting the oxide layer 41 is analyzed by an energy dispersive spectroscopy (EDS) device. The Cr content in the Cr oxide is not particularly limited, but may be, for example, 20 mol % to 100 mol % among the metal elements.

[0077] The Cr content in the metal elements in the Cr oxide constituting the oxide layer 41 is preferably 50 mol % or more. This makes it possible to significantly suppress the diffusion of Cr contained in the support substrate 3 and the main body portion 40 into the oxide layer 41.

[0078] The Cr oxide constituting the oxide layer 41 is preferably composed of at least one of chromium oxide and chromium manganese oxide. These oxides have a property that Cr is particularly difficult to diffuse, and therefore the durability of the oxide layer 41 can be improved.

[0079] Chromium oxide is Cr 2 O 3 Examples of chromium manganese oxide include MnCr 2 O 4 (Spinel), Mn 1,5 Cr 1,5 O 4 (Spinel), etc.

[0080] The Cr oxide constituting the oxide layer 41 is preferably crystalline. This makes it possible to prevent the oxide layer 41 from being damaged due to a phase transition of the Cr oxide from amorphous to crystalline even when the electrolysis cell 100 is operated for a long period of time.

[0081] The Cr oxide constituting the oxide layer 41 preferably has a spinel or corundum crystal structure. These crystal structures have high symmetry, and therefore the thermal stress resistance of the oxide layer 41 can be improved.

[0082] The oxide layer 41 can be formed by applying a paste containing Cr oxide onto the side surface of each protrusion 403, followed by heat treatment. The conditions for the heat treatment can be appropriately set, for example, at 600° C. or higher and 1100° C. or lower, and for 0.5 hours or higher and 24 hours or lower.

[0083] The oxide layer 41 is thinner than the cell body 2. The thickness of the oxide layer 41 can be, for example, not less than 0.1 μm and not more than 20 μm.

[0084] FIG. 4 is an enlarged cross-sectional view of the first convex portion 403a as viewed in the thickness direction, and FIG. 5 is a cross-sectional view taken along line VV in FIG. 4. As shown in FIGS. 4 and 5, each oxide layer 41 has an upstream portion 411 and a downstream portion 412. The upstream portion 411 is a portion of the oxide layer 41 facing the upstream side. The downstream portion 412 is a portion of the oxide layer 41 facing the downstream side. For example, when the upper side of FIG. 4 is the upstream side and the lower side is the downstream side, a line extending directly upward from the center O of the convex portion 403 is set to 0 degrees, and a range of ±45 degrees from the line is the upstream portion 411. In addition, a line extending directly downward from the center O of the convex portion 403 is set to 0 degrees, and a range of ±45 degrees from the line is the downstream portion 412.

[0085] At least one of the oxide layers 41 has a thickness distribution that induces warping such that the main body portion 40 bulges toward the second main surface 402 side.

[0086] In detail, first, in the oxide layer 41 formed on the side surface of each first convex portion 403a, the thickness ta1 of the upstream portion 411 is thinner than the thickness ta2 of the downstream portion 412. For example, in the oxide layer 41 formed on the side surface of each first convex portion 403a, the average value of the thickness ta1 of the upstream portion 411 is smaller than the average value of the thickness ta2 of the downstream portion 412.

[0087] In the oxide layer 41 formed on the side surface of at least one first protrusion 403a, the ratio (ta1 / ta2) of the thickness ta1 to the thickness ta2 can be set to 0.83 or less. Also, this ratio (ta1 / ta2) can be set to 0.1 or more.

[0088] In the oxide layer 41 formed on the side surface of each first convex portion 403a, the thickness ta1 of the upstream portion 411 and the thickness ta2 of the downstream portion 412 can be measured as follows. First, each first convex portion 403a is cut along the gas flow direction (Y-axis direction) so as to pass through the center of each first convex portion 403a, and a cut surface as shown in FIG. 5 is created for each first convex portion 403a. Then, in each cut surface, the upstream portion 411 and the downstream portion 412 of each first convex portion 403a are photographed by an electron microscope (SEM) at a magnification (200 to 20,000 times) suitable for measuring the thickness. Note that the vicinity of the center in the height direction of each first convex portion 403a is photographed.

[0089] Then, in each SEM image, the thickness ta1 of the upstream portion 411 and the thickness ta2 of the downstream portion 412 are measured. Note that the thickness ta1 of the upstream portion 411 and the thickness ta2 of the downstream portion 412 are measured at the center in the height direction of the first convex portion 403a.

[0090] Fig. 6 is an enlarged cross-sectional view of the second convex portion 403b as viewed in the thickness direction, and Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 6. As shown in Figs. 6 and 7, in the oxide layer 41 formed on the side surface of each second convex portion 403b, the thickness tb1 of the upstream portion 411 is thicker than the thickness tb2 of the downstream portion 412. For example, in the oxide layer 41 formed on the side surface of each second convex portion 403b, the average value of the thickness tb1 of the upstream portion 411 is greater than the average value of the thickness tb2 of the downstream portion 412.

[0091] In the oxide layer 41 formed on the side surface of at least one second protrusion 403b, the ratio of the thickness tb1 to the thickness tb2 (tb1 / tb2) can be set to 1.2 or more. Also, this ratio (tb1 / tb2) can be set to 10 or less.

[0092] In the oxide layer 41 formed on the side surface of each second convex portion 403b, the thickness tb1 of the upstream portion 411 and the thickness tb2 of the downstream portion 412 can be measured as follows. First, each second convex portion 403b is cut along the gas flow direction (Y-axis direction) so as to pass through the center of each second convex portion 403b, and a cut surface as shown in FIG. 7 is created for each second convex portion 403b. Then, in each cut surface, the upstream portion 411 and the downstream portion 412 of the second convex portion 403b are photographed by an electron microscope (SEM) at a magnification (200 to 20,000 times) suitable for measuring the thickness. Note that the vicinity of the center in the height direction of each second convex portion 403b is photographed.

[0093] Then, in each SEM image, the thickness tb1 of the upstream portion 411 and the thickness tb2 of the downstream portion 412 are measured. Note that the thickness tb1 of the upstream portion 411 and the thickness tb2 of the downstream portion 412 are measured at the center in the height direction of the second convex portion 403b.

[0094] Fig. 8 is an enlarged cross-sectional view of the third convex portion 403c as viewed in the thickness direction, and Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 8. As shown in Figs. 8 and 9, in the oxide layer 41 formed on the side surface of each third convex portion 403c, the thickness tc1 of the upstream portion 411 and the thickness tc2 of the downstream portion 412 are substantially the same. For example, in the oxide layer 41 formed on the side surface of each third convex portion 403c, the average value of the thickness tc1 of the upstream portion 411 is substantially the same as the average value of the thickness tc2 of the downstream portion 412.

[0095] In the oxide layer 41 formed on the side surface of at least one third protrusion 403c, the ratio of the thickness tc1 to the thickness tc2 (tc1 / tc2) can be set to be not less than 0.83 and not more than 1.2.

[0096] The thickness difference (tc1-tc2) between the upstream portion 411 and the downstream portion 412 in the oxide layer 41 arranged on the side surface of the third convex portion 403c is smaller than the thickness difference (ta1-ta2) between the upstream portion 411 and the downstream portion 412 in the oxide layer 41 arranged on the side surface of the first convex portion 403a. The thickness difference (tc1-tc2) between the upstream portion 411 and the downstream portion 412 in the oxide layer 41 arranged on the side surface of the third convex portion 403c is smaller than the thickness difference (tb1-tb2) between the upstream portion 411 and the downstream portion 412 in the oxide layer 41 arranged on the side surface of the second convex portion 403b. Here, the thickness difference between the upstream portion 411 and the downstream portion 412 is an absolute value.

[0097] In the oxide layer 41 formed on the side surface of each third convex portion 403c, the thickness tc1 of the upstream portion 411 and the thickness tc2 of the downstream portion 412 can be measured as follows. First, each third convex portion 403c is cut along the gas flow direction (Y-axis direction) so as to pass through the center of each third convex portion 403c, and a cut surface as shown in FIG. 9 is created for each third convex portion 403c. Then, in each cut surface, the upstream portion 411 and the downstream portion 412 of the third convex portion 403c are photographed by an electron microscope (SEM) at a magnification (200 to 20,000 times) suitable for measuring the thickness. Note that the vicinity of the center in the height direction of each third convex portion 403c is photographed.

[0098] Then, in each SEM image, the thickness tc1 of the upstream portion 411 and the thickness tc2 of the downstream portion 412 are measured. Note that the thickness tc1 of the upstream portion 411 and the thickness tc2 of the downstream portion 412 are measured at the center in the height direction of the third convex portion 403c.

[0099] The oxide layer 41 disposed on the side surface of the third protrusion 403c is thicker than the oxide layer 41 disposed on the side surface of the first protrusion 403a. cThe average thickness of the oxide layer 41 disposed on the side surface of the third protrusion 403c is greater than the average thickness of the oxide layer 41 disposed on the side surface of each first protrusion 403a. Also, the oxide layer 41 disposed on the side surface of the third protrusion 403c is thicker than the oxide layer 41 disposed on the side surface of the second protrusion 403b. For example, c The average thickness of the oxide layer 41 disposed on the side surface of each second protrusion 403b is greater than the average thickness of the oxide layer 41 disposed on the side surface of each second protrusion 403b. Here, the thickness of the oxide layer 41 can be the average thickness of the upstream portion 411 and the downstream portion 412.

[0100] In the oxide layer 41 formed on the side surface of each convex portion 403 arranged between the first convex portion 403a and the third convex portion 403c, the upstream portion 411 is preferably thinner than the downstream portion 412. Also, in the oxide layer 41 formed on the side surface of each convex portion 403 arranged between the second convex portion 403b and the third convex portion 403c, the upstream portion 411 is preferably thicker than the downstream portion 412. The difference in thickness between the upstream portion 411 and the downstream portion 412 is preferably smaller toward the third convex portion 403c.

[0101] In the interconnector 4 configured as described above, in the oxide layer 41 formed on the side surface of each first convex portion 403a, the downstream portion 412 is thicker than the upstream portion 411. For this reason, when the temperature is lowered to room temperature after the oxide layer 41 is formed, a thermal stress is generated in the region where each first convex portion 403a of the interconnector 4 is formed, which induces a warp that bulges toward the second main surface 402 side, as shown by the arrow in FIG.

[0102] In addition, in the oxide layer 41 formed on the side surface of each second convex portion 403b, the upstream portion 411 is thicker than the downstream portion 412. For this reason, when the temperature is lowered to room temperature after the formation of the oxide layer 41, a thermal stress is generated in the region where each second convex portion 403b of the interconnector 4 is formed, which induces warping such that the interconnector 4 bulges toward the second main surface 402, as shown by the arrow in FIG.

[0103] As described above, since the interconnector 4 is warped so as to bulge toward the second main surface 402, when the electrolysis cells 100 are stacked, even if there are unevenness on the cell main body portion located below the interconnector 4, the unevenness can be absorbed.

[0104] [Variations] 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.

[0105] (a) In the above embodiment, the convex portion 403 has a circular shape in a plan view, but the shape of the convex portion 403 is not limited to this. For example, as shown in Fig. 12, each convex portion 403 may have a rectangular shape in a plan view. Also, each convex portion 403 may extend in the gas flow direction. Each convex portion 403 is disposed at intervals from each other in the first direction.

[0106] The multiple convex portions 403 include a first convex portion 403a, a second convex portion 403b, and a third convex portion 403c. The first convex portion 403a and the second convex portion 403b are convex portions arranged on the outermost sides in the first direction. The convex portions 403 other than the first convex portion 403a and the second convex portion 403b are arranged between the first convex portion 403a and the second convex portion 403b in the first direction.

[0107] The third convex portion 403c is disposed in the center between the first convex portion 403a and the second convex portion 403b in the first direction. That is, among the multiple convex portions 403, the third convex portion 403c is the convex portion that is closest to the midpoint between the first convex portion 403a and the second convex portion 403b in the first direction.

[0108] Fig. 13 is a cross-sectional view taken along line XIII-XIII in Fig. 12. As shown in Fig. 13, the oxide layer 41 has an outer portion 413 and an inner portion 414. The outer portion 413 is a portion facing outward in the first direction. The inner portion 414 is a portion facing inward in the first direction. In other words, the inner portion 414 faces toward the center of the interconnector 4 in the first direction.

[0109] In the oxide layer 41 disposed on the side surface of the first protrusion 403a, the thickness ta1 of the outer portion 413 is thinner than the thickness ta2 of the inner portion 414. For example, in the oxide layer 41 formed on the side surface of the first protrusion 403a, the ratio of the thickness ta1 to the thickness ta2 (ta1 / ta2) can be 0.83 or less. Moreover, this ratio (ta1 / ta2) can be 0.1 or more.

[0110] 14, in the oxide layer 41 disposed on the side surface of the second protrusion 403b, the thickness tb1 of the outer portion 413 is smaller than the thickness tb2 of the inner portion 414. For example, in the oxide layer 41 formed on the side surface of the second protrusion 403b, the ratio (tb1 / tb2) of the thickness tb1 to the thickness tb2 can be set to 0.83 or less. Moreover, this ratio (tb1 / tb2) can be set to 0.1 or more.

[0111] 15, in the oxide layer 41 disposed on the side surface of the third convex portion 403c, the thickness tc1 of the outer portion 413 is substantially the same as the thickness tc2 of the inner portion 414. For example, in the oxide layer 41 formed on the side surface of the third convex portion 403c, the ratio of the thickness tc1 to the thickness tc2 (tc1 / tc2) can be 0.83 or more and 1.2 or less. When the third convex portion 403c is disposed at the center of the interconnector 4 in the first direction, the portion of the oxide layer 41 disposed on the side surface of the third convex portion 403c facing the first convex portion 403a side is defined as the outer portion 413, and the portion facing the second convex portion 403b side is defined as the inner portion 414.

[0112] The thickness difference (tc1-tc2) between the outer portion 413 and the inner portion 414 of the oxide layer 41 arranged on the side surface of the third convex portion 403c is smaller than the thickness difference (ta1-ta2) between the outer portion 413 and the inner portion 414 of the oxide layer 41 arranged on the side surface of the first convex portion 403a. The thickness difference (tc1-tc2) between the outer portion 413 and the inner portion 414 of the oxide layer 41 arranged on the side surface of the third convex portion 403c is smaller than the thickness difference (tb1-tb2) between the outer portion 413 and the inner portion 414 of the oxide layer 41 arranged on the side surface of the second convex portion 403b. Here, the thickness difference between the outer portion 413 and the inner portion 414 is an absolute value.

[0113] The thickness of each of the outer parts 413 and the inner parts 414 can be measured as follows. First, the interconnector 4 is cut along the first direction so as to pass through the upstream end, downstream end, and center of each of the convex parts 403, respectively, to create three cut surfaces. Then, in each cut surface, the outer parts 413 and the inner parts 414 of the first convex part 403a, the second convex part 403b, and the third convex part 403c are photographed by an electron microscope (SEM) at a magnification (200 to 20,000 times) suitable for measuring the thickness. The first convex part 403a, the second convex part 403b, and the third convex part 403c are photographed near their centers in the height direction.

[0114] Then, in each SEM image, the thickness ta1 of the outer portion 413 and the thickness ta2 of the inner portion 414 are measured at the upstream end, downstream end, and center of the first convex portion 403a, and the average value of the thicknesses ta1 of the outer portions 413 is set as the thickness ta1 of the outer portion 413 of the first convex portion 403a, and the average value of the thicknesses ta2 of the inner portions 414 is set as the thickness ta2 of the inner portion 414 of the first convex portion 403a. Similarly, the thicknesses of the second convex portion 403b and the third convex portion 403c are calculated.

[0115] The oxide layer 41 disposed on the side surface of the third convex portion 403c is thicker than the oxide layer 41 disposed on the side surface of the first convex portion 403a. Also, the oxide layer 41 disposed on the side surface of the third convex portion 403c is thicker than the oxide layer 41 disposed on the side surface of the second convex portion 403b. Here, the thickness of the oxide layer 41 can be the average value of the thickness of the outer portion 413 and the thickness of the inner portion 414.

[0116] In the interconnector 4 configured as described above, in the oxide layer 41 formed on the side surface of the first convex portion 403a, the inner portion 414 is thicker than the outer portion 413. For this reason, when the temperature is lowered to room temperature after the formation of the oxide layer 41, a thermal stress is generated in the region where the first convex portion 403a of the interconnector 4 is formed, which induces a warp that bulges toward the second main surface 402, as shown by the arrow in FIG.

[0117] Moreover, in the oxide layer 41 formed on the side surface of the second convex portion 403b, the inner portion 414 is thicker than the outer portion 413. For this reason, when the temperature is lowered to room temperature after the formation of the oxide layer 41, a thermal stress is generated in the region where the second convex portion 403b of the interconnector 4 is formed, which induces a warp that bulges toward the second main surface 402 as shown by the arrow in FIG.

[0118] (b) In the above embodiment, the oxide layer 41 formed on the side surface of the second convex portion 403b has an upstream portion 411 that is thicker than the downstream portion 412, but the configuration of the oxide layer 41 is not limited to this. For example, the oxide layer 41 formed on the side surface of the second convex portion 403b may have an upstream portion 411 and a downstream portion 412 that are substantially the same in thickness.

[0119] (c) 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 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 also includes, for example, a fuel cell that uses oxide ions or protons as a carrier. [Explanation of symbols]

[0120] 100: Electrolytic cell 2: Cell body 3: Support substrate 4: Interconnector 40: Main body 401: First main surface 402: Second main surface 403: Convex 403a: First protrusion 403b: Second convex part 403c: Third convex part 41: Oxide layer 411:Upstream part 412: Downstream part 413 :Outer part 414 :Inner part

Claims

1. A main body portion having a first main surface facing a support substrate, a second main surface facing the opposite side to the first main surface, and a plurality of protrusions, supply holes, and discharge holes formed on the first main surface; A plurality of oxide layers disposed on the side surfaces of each of the protrusions; Equipped with The plurality of protrusions are arranged at intervals from one another in a gas flow direction, the plurality of protruding portions include a first protruding portion disposed at the most upstream position in the gas flow direction and a second protruding portion disposed at the most downstream position, Each of the oxide layers has an upstream portion facing the upstream side and a downstream portion facing the downstream side, the oxide layer disposed on the side surface of the first protrusion has a thickness distribution in which the upstream portion is thinner than the downstream portion. Interconnector.

2. the oxide layer disposed on the side surface of the second protrusion has a thickness distribution in which the upstream portion is thicker than the downstream portion. The interconnector according to claim 1 .

3. the plurality of protruding portions include a third protruding portion disposed in a central portion between the first protruding portion and the second protruding portion in the gas flow direction, a difference in thickness between an upstream portion and a downstream portion of the oxide layer disposed on the side surface of the first protrusion is larger than a difference in thickness between an upstream portion and a downstream portion of the oxide layer disposed on the side surface of the third protrusion; The interconnector according to claim 1 .

4. the plurality of protruding portions include a third protruding portion disposed in a central portion between the first protruding portion and the second protruding portion in the gas flow direction, the oxide layer disposed on the side surface of the third protrusion is thicker than the oxide layer disposed on the side surface of the first protrusion and is thicker than the oxide layer disposed on the side surface of the second protrusion; The interconnector according to claim 1 .

5. A main body portion having a first main surface facing a support substrate, a second main surface facing the opposite side to the first main surface, and a plurality of protrusions, supply holes, and discharge holes formed on the first main surface; A plurality of oxide layers disposed on the side surfaces of each of the protrusions; Equipped with The plurality of protrusions extend in a gas flow direction and are arranged at intervals from one another in a first direction perpendicular to the gas flow direction, the plurality of protruding portions include a first protruding portion disposed on the outermost side in the first direction, and a second protruding portion disposed on the outermost side on a side opposite to the first protruding portion in the first direction, each of the oxide layers has an outer portion facing outward in the first direction and an inner portion facing inward in the first direction; the oxide layer disposed on the side surface of the first protrusion has a thickness distribution in which the outer portion is thinner than the inner portion. Interconnector.

6. the oxide layer disposed on the side surface of the second protrusion has a thickness distribution in which the outer portion is thinner than the inner portion. The interconnector according to claim 5 .

7. the plurality of protruding portions include a third protruding portion disposed in a central portion between the first protruding portion and the second protruding portion in the first direction, a difference in thickness between an outer portion and an inner portion of the oxide layer disposed on the side surface of the first protrusion is greater than a difference in thickness between the outer portion and the inner portion of the oxide layer disposed on the side surface of the third protrusion; The interconnector according to claim 5 .

8. the plurality of protruding portions include a third protruding portion disposed in a central portion between the first protruding portion and the second protruding portion in the first direction, the oxide layer disposed on the side surface of the third protrusion is thicker than the oxide layer disposed on the side surface of the first protrusion and is thicker than the oxide layer disposed on the side surface of the second protrusion; The interconnector according to claim 5 .

9. The main body is made of an alloy including chromium, Each of the oxide layers is mainly composed of chromium. The interconnector according to claim 1 or 5.

10. Each of the oxide layers has a smaller thermal expansion coefficient than the main body portion. The interconnector according to claim 1 or 5.

11. An interconnector according to claim 1 or 5; A support substrate attached to the interconnector; A cell main body portion disposed on the support substrate; An electrochemical cell comprising:

12. Each of the oxide layers is thinner than the cell body.

12. The electrochemical cell of claim 11.

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