Electrochemical cell

Abstract

To provide an electrochemical cell capable of preventing a first electrode layer from being peeled from an electrolyte layer, while maintaining a gas diffusion property in the first electrode layer.SOLUTION: An electrolysis cell 1 comprises a metal support 10 and a cell body part 20. The cell body part 20, arranged on a first main face 12 of the metal support 10, comprises a hydrogen electrode layer 6 that covers a plurality of communication holes 11, an oxygen electrode layer 9, and an electrolyte layer 7. The hydrogen electrode layer 6 comprises a plurality of island-like parts 61 connected to the electrolyte layer 7, and a layer-like part 62 that covers the plurality of island-like parts 61 and is connected to the electrolyte layer 7. A porosity of each of the plurality of island-like parts 61 is lower than a porosity of the layer-like part 62.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to electrochemical cells. [Background technology]

[0002] Conventionally, metal-supported electrochemical cells (electrolysis cells, fuel cells, etc.) have been known that include a cell body disposed on a metal support (see, for example, Patent Document 1). The metal support has a plurality of communication holes formed in its main surface. The cell body has a first electrode layer and a second electrode layer disposed on the main surface of the metal support, and an electrolyte layer disposed between the first and second electrode layers. Gas supplied through each communication hole is diffused into the first electrode layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7333439 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrochemical cell described in Patent Document 1, the first electrode layer must be fired at a low temperature because firing the first electrode layer at a high temperature would deteriorate the metal support. However, firing the first electrode layer at a low temperature results in low sinterability, which reduces the overall porosity of the first electrode layer. As a result, the adhesion of the first electrode layer to the electrolyte layer is reduced, making the first electrode layer prone to peeling off from the electrolyte layer.

[0005] An object of the present invention is to provide an electrochemical cell that can prevent the first electrode layer from peeling off from the electrolyte layer while maintaining the gas diffusibility in the first electrode layer. [Means for solving the problem]

[0006] An electrochemical cell according to a first aspect of the present invention includes a metal support having a plurality of communication holes formed in a principal surface thereof and a cell main body disposed on the principal surface. The cell main body includes a hydrogen electrode layer disposed on the principal surface and covering the plurality of communication holes, an oxygen electrode layer, and an electrolyte layer disposed between the hydrogen electrode layer and the oxygen electrode layer. The hydrogen electrode layer includes a plurality of island portions connected to the electrolyte layer and a layer portion covering the plurality of island portions and connected to the electrolyte layer. The porosity of each of the plurality of island portions is lower than the porosity of the layer portion.

[0007] An electrochemical cell according to a second aspect of the present invention is related to the first aspect, wherein the plurality of island-shaped portions include island-shaped portions that are tapered toward the metal support in a cross section along the thickness direction.

[0008] An electrochemical cell according to a third aspect of the present invention is related to the first or second aspect, wherein the plurality of island-shaped portions include island-shaped portions that are tapered toward the electrolyte layer side in a cross section along the thickness direction.

[0009] An electrochemical cell according to a fourth aspect of the present invention is related to any one of the first to third aspects, wherein a central portion of the island portion in a surface direction does not overlap with the communication hole in a thickness direction of the hydrogen electrode layer.

[0010] An electrochemical cell according to a fifth aspect of the present invention is the electrochemical cell according to any one of the first to fourth aspects, wherein, when the thickness of the electrolyte layer is 30 μm or less and the spacing between the plurality of island-shaped portions is 0.5 mm or less, the coverage of the surface of the electrolyte layer facing the hydrogen electrode layer by the plurality of island-shaped portions is 27% or more, and the average equivalent circle diameter of the plurality of island-shaped portions in a plan view of the surface of the electrolyte layer facing the hydrogen electrode layer is 0.16 mm or more.

[0011] An electrochemical cell according to a sixth aspect of the present invention is the electrochemical cell according to any one of the first to fourth aspects, wherein when the average thickness of the plurality of island-shaped portions is 30 μm or less and the spacing between the plurality of island-shaped portions is 0.5 mm or less, the coverage of the hydrogen electrode layer side surface of the electrolyte layer by the plurality of island-shaped portions is 37% or more, and the average circle-equivalent diameter of the hydrogen electrode layer side surface of the electrolyte layer in a plan view is 0.55 mm or more. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an electrochemical cell that can prevent the first electrode layer from peeling off from the electrolyte layer while maintaining the gas diffusibility in the first electrode layer. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a cross-sectional view of an electrolysis cell according to an embodiment. [Figure 2] FIG. 2 is a partially enlarged view of FIG. [Figure 3] FIG. 3 is a plan view showing the configuration of the island portions of the hydrogen electrode layer. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Electrolysis cell 1) Fig. 1 is a cross-sectional view of an electrolytic cell 1 according to an embodiment. Fig. 2 is a partially enlarged view of Fig. 1. The electrolytic cell 1 is an example of an "electrochemical cell" according to the present invention. The electrolytic cell 1 is a so-called metal-supported electrolytic cell.

[0015] As shown in FIG. 1, the electrolysis cell 1 includes a metal support 10, a cell main body 20, and a flow path member 30.

[0016] [Metal support 10] The metal support 10 supports the cell main body 20. The metal support 10 is formed in a plate shape. The metal support 10 may be in the shape of a flat plate or a curved plate. The metal support 10 only needs to be able to support the cell main body 20, and its thickness is not particularly limited, but can be, for example, 0.1 mm or more and 2.0 mm or less.

[0017] As shown in FIG. 1, the metal support 10 has a plurality of communicating holes 11, a first main surface 12, and a second main surface 13.

[0018] Each communication hole 11 penetrates the metal support 10 from the first main surface 12 to the second main surface 13. Each communication hole 11 opens to the first main surface 12 and the second main surface 13. The opening of each communication hole 11 on the first main surface 12 side is covered by the hydrogen electrode layer 6, which will be described later. The opening of each communication hole 11 on the second main surface 13 side is connected to a flow path 30a, which will be described later.

[0019] Each of the communication holes 11 can be formed by mechanical processing (for example, punching), laser processing, or chemical processing (for example, etching). When the metal support 10 is made of porous metal, each of the communication holes 11 may be a communication hole formed by interconnecting open pores of the porous metal. Each of the communication holes 11 may be perpendicular to the first main surface 12, or may not be perpendicular to the first main surface 12, and may not be linear.

[0020] The cell main body 20 is bonded to the first main surface 12. The flow path member 30 is bonded to the second main surface 13. The first main surface 12 is provided on the opposite side of the second main surface 13.

[0021] The metal support 10 is made of a metal material. For example, the metal support 10 is made of an alloy material containing Cr (chromium). Examples of such metal materials include Fe-Cr alloy steel (stainless steel, etc.) and Ni-Cr alloy steel. The Cr content of the metal support 10 is not particularly limited, but can be set to 4% by mass or more and 30% by mass or less.

[0022] At least a portion of the surface of the metal support 10 may be covered with an oxide film formed by oxidation of the constituent elements of the metal support 10. A typical example of the oxide film is a chromium oxide film. The oxide film may cover at least a portion of the inner wall surface of each communicating hole 11.

[0023] [Cell body 20] The cell body 20 is disposed on the metal support 10. The cell body 20 has a hydrogen electrode layer 6 (cathode), an electrolyte layer 7, a reaction prevention layer 8, and an oxygen electrode layer 9 (anode).

[0024] The hydrogen electrode layer 6, electrolyte layer 7, reaction prevention layer 8, and oxygen electrode layer 9 are laminated in this order from the metal support 10 side. The hydrogen electrode layer 6, electrolyte layer 7, and oxygen electrode layer 9 are essential components, while the reaction prevention layer 8 is optional.

[0025] [Hydrogen electrode layer 6] The hydrogen electrode layer 6 is disposed on the first main surface 12 of the metal support 10. The hydrogen electrode layer 6 is disposed between the metal support 10 and the electrolyte layer 7. The hydrogen electrode layer 6 is supported by the metal support 10.

[0026] A source gas is supplied to the hydrogen electrode layer 6 through each of the communication holes 11. The source gas contains at least H2O.

[0027] When the raw material gas contains only H2O, the hydrogen electrode layer 6 generates H2 from the raw material gas in accordance with the electrochemical reaction of water electrolysis shown in the following formula (1).

[0028] Hydrogen electrode layer 6: H2O+2e - →H2+O 2- ···(1)

[0029] When the raw material gas contains CO in addition to H O, the hydrogen electrode layer 6 converts H, CO, and O from the raw material gas in accordance with the electrochemical reactions of co-electrolysis shown in the following formulas (2), (3), and (4): 2- Generate.

[0030] Hydrogen electrode layer 6: 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)

[0031] 2, the hydrogen electrode layer 6 includes a plurality of island portions 61, a layer portion 62, and a plurality of extension portions 63. The plurality of island portions 61 and the layer portion 62 are essential components, while the plurality of extension portions 63 are optional components. In FIG. 2, two island portions 61 (a right-side island portion 61a and a left-side island portion 61b) are shown.

[0032] <Island 61> Each island portion 61 is connected to the electrolyte layer 7. Each island portion 61 is disposed on the hydrogen electrode layer side surface 7S of the electrolyte layer 7. Each island portion 61 is embedded in the layer portion 62, and only the surface connected to the electrolyte layer 7 is exposed from the layer portion 62. The island portions 61 are spaced apart from each other in the planar direction. In this specification, the planar direction refers to a direction parallel to an approximation line of the hydrogen electrode layer side surface 7S obtained by the least squares method. In the following description, the direction perpendicular to the planar direction is referred to as the thickness direction.

[0033] The porosity of each island portion 61 is lower than the porosity of the layer portion 62. This improves the connectivity between each island portion 61 and the electrolyte layer 7 compared to the connectivity between the layer portion 62 and the electrolyte layer 7. Therefore, the connectivity between the hydrogen electrode layer 6 and the electrolyte layer 7 is improved compared to when each island portion 61 is not present. Furthermore, gas diffusibility in the layer portion 62 can be ensured, and gas can be smoothly supplied from the layer portion 62 to each island portion 61, so gas diffusibility in the hydrogen electrode layer 6 can be maintained.

[0034] The porosity of each island portion 61 can be 10% or more and 30% or less. The porosity of the island portion 61 is calculated using the following method. First, a cross section of the hydrogen electrode layer 6 along the thickness direction after reduction treatment is exposed. The reduction treatment involves supplying a reducing gas at 750°C (e.g., 78% H2 gas humidified at 90°C) to the hydrogen electrode layer 6 for 4 hours. Next, a backscattered electron image of the cross section of the hydrogen electrode layer 6 is acquired at 10,000x magnification using an SEM device. Next, using image analysis software Image-Pro manufactured by MEDIACYBERNETICS, the black areas (corresponding to pores) in the backscattered electron image are identified. Then, the island portion 61 and the layer portion 62 are separated along the line where the porosity changes significantly in the backscattered electron image. Next, the porosity of the island portion 61 is calculated by dividing the total area of ​​the pores in the island portion 61 by the total area of ​​the island portion 61 in the backscattered electron image.

[0035] The average pore size in the island portions 61 is preferably smaller than the average pore size in the layer portions 62. This makes it possible to improve the connectivity between each island portion 61 and the electrolyte layer 7 compared to the connectivity between the layer portions 62 and the electrolyte layer 7, and also improve the gas diffusivity in the hydrogen electrode layer 6.

[0036] The average pore diameter in the island-shaped portion 61 can be 0.01 μm or more and 2.0 μm or less. The average pore diameter in the island-shaped portion 61 is calculated by arithmetically averaging the circle-equivalent diameters of 50 pores randomly selected from within the island-shaped portion 61 on the backscattered electron image described above. The circle-equivalent diameter of a pore is the diameter of a circle having the same area as the cross-sectional area of ​​the pore.

[0037] 2, the cross-sectional shape of the island-shaped portion 61a on the left side is tapered toward the metal support 10. By tapering the cross-sectional shape of the island-shaped portion 61 toward the metal support 10 in this way, the flow rate of the source gas diffusing from each communication hole 11 of the metal support 10 toward the electrolyte layer 7 can be increased. Therefore, the gas diffusibility in the layer-shaped portion 62 can be improved.

[0038] 2, the cross-sectional shape of the island-shaped portion 61b on the left side is tapered toward the electrolyte layer 7. By tapering the cross-sectional shape of the island-shaped portion 61 toward the electrolyte layer 7 in this way, the anchor effect of the layer-shaped portion 62, which will be described later, can be strengthened.

[0039] The plurality of island-shaped portions 61 preferably include both island-shaped portions 61a and island-shaped portions 61b. This makes it possible to improve both the gas diffusibility and the anchoring effect of the layer-shaped portion 62. The ratio of the number of island-shaped portions 61a and the number of island-shaped portions 61b in the plurality of island-shaped portions 61 can be appropriately set depending on whether emphasis is placed on improving gas diffusibility or improving the anchoring effect. The plurality of island-shaped portions 61 may include island-shaped portions 61 having a cross-sectional shape different from the island-shaped portions 61a and the island-shaped portions 61b.

[0040] 2, it is preferable that the central portion of the island-shaped portion 61 in the planar direction does not overlap with the through-holes 11 of the metal support 10 in the thickness direction. This can prevent peeling from occurring between the island-shaped portion 61 and the layer-shaped portion 62. The central portion of the island-shaped portion 61 in the planar direction refers to the central portion when the island-shaped portion 61 is divided into three equal parts in the planar direction.

[0041] Each island-shaped portion 61 is made of Ni and a ceramic material. Each island-shaped portion 61 may contain Ni as NiO. Examples of the ceramic material that can be used include Y2O3 (yttria), YSZ, GDC, ScSZ, SDC, CSZ (calcia-stabilized zirconia), MSZ (magnesia-stabilized zirconia), YbSZ, and a mixed material of two or more of these.

[0042] The average thickness of the island portions 61 can be 5 μm or more and 50 μm or less. The average thickness of the island portions 61 is the arithmetic mean value of the thicknesses of 50 randomly selected island portions 61. The thickness of one island portion 61 is the maximum thickness of the island portion 61 in a cross section along the thickness direction. From the viewpoint of workability in the manufacturing process, the average thickness of the island portions 61 is preferably 10 μm or more.

[0043] 3 is a schematic diagram showing the arrangement of a plurality of island portions 61 in a plan view of the hydrogen electrode layer side surface 7S. In FIG. 3, the layer portions 62 are not shown.

[0044] The island-shaped portions 61 are arranged continuously and regularly in the surface direction. In Fig. 3, the shape of each island-shaped portion 61 in a plan view is approximately hexagonal, but the shape of each island-shaped portion 61 in a plan view can be changed as appropriate. For example, the shape of each island-shaped portion 61 in a plan view can be circular, elliptical, triangular or higher polygonal.

[0045] The spacing between the island-shaped portions 61 can be 0.05 mm or more and 5 mm or less. The spacing is the arithmetic mean value of the spacing between 50 randomly selected gaps 64. The spacing between the gaps 64 is the shortest distance between two adjacent island-shaped portions 61. From the viewpoint of improving electrode function, it is preferable that the spacing between the island-shaped portions 61 is narrow.

[0046] The coverage of the island-shaped portions 61 on the hydrogen electrode layer side surface 7S can be 20% or more and 80% or less. The coverage of the island-shaped portions 61 is calculated by dividing the total area of ​​the island-shaped portions 61 by the total area of ​​the hydrogen electrode layer side surface 7S.

[0047] The average equivalent circle diameter of the island-shaped portions 61 can be 0.1 mm or more and 5 mm or less. The average equivalent circle diameter is the arithmetic mean value of the equivalent circle diameters of 50 randomly selected island-shaped portions 61. The equivalent circle diameter of the island-shaped portions 61 is the diameter of a circle having the same area as the island-shaped portion 61 in a plan view of the hydrogen electrode layer side surface 7S of the electrolyte layer 7. Note that, from the viewpoint of suppressing warping of the electrolyte layer 7, it is preferable that the average equivalent circle diameter of the island-shaped portions 61 is small.

[0048] When the thickness of the electrolyte layer 7 is 30 μm or less and the spacing between the island-shaped portions 61 is 0.5 mm or less, it is preferable that the coverage rate of the island-shaped portions 61 is 27% or more and the average equivalent circle diameter of the island-shaped portions 61 is 0.16 mm or more. This makes it possible to suppress warping of the electrolyte layer 7.

[0049] Furthermore, when the average thickness of the island-shaped portions 61 is 30 μm or less and the spacing between the island-shaped portions 61 is 0.5 mm or less, it is preferable that the coverage rate of the island-shaped portions 61 is 37% or more and the average equivalent circle diameter of the island-shaped portions 61 is 0.55 mm or more. This makes it possible to suppress warping of the electrolyte layer 7.

[0050] <Layer portion 62> The layer portion 62 covers each island portion 61 and is connected to the electrolyte layer 7. The layer portion 62 is connected to the first main surface 12 of the metal support 10. The layer portion 62 is connected to the electrolyte layer 7 at the gaps 64 between the island portions 61. The layer portion 62 enters the gaps 64 between the island portions 61, creating an anchor effect, which improves the connectivity between each island portion 61 and the layer portion 62.

[0051] The porosity of the layer portion 62 is lower than the porosity of each island portion 61. The porosity of the layer portion 62 can be 40% or more and 55% or less. The porosity of the layer portion 62 is calculated by dividing the total area of ​​the pores in the layer portion 62 by the total area of ​​the layer portion 62 on the backscattered electron image described above. Note that, like the porosity of the island portion 61 described above, the porosity of the layer portion 62 is a value after reduction treatment.

[0052] The average pore diameter in the layer-shaped portion 62 is preferably larger than the average pore diameter in each of the island-shaped portions 61. The average pore diameter in the layer-shaped portion 62 can be 0.01 μm or more and 1.0 μm or less. The average pore diameter in the layer-shaped portion 62 is calculated by arithmetically averaging the circle-equivalent diameters of 50 pores randomly selected from within the layer-shaped portion 62 on the backscattered electron image described above.

[0053] The layer portion 62 is composed of Ni and a ceramic material. The layer portion 62 may contain Ni as NiO. The ceramic material may be Y2O3, YSZ, GDC, ScSZ, SDC, CSZ, MSZ, YbSZ, or a mixed material of two or more of these.

[0054] The thickness of the layer portion 62 can be 5 μm or more and 100 μm or less. The thickness of the layer portion 62 is calculated by measuring the shortest distance in the thickness direction between each island portion 61 and the metal support 10 for each island portion 61 and arithmetically averaging the measured values. From the viewpoint of workability in the manufacturing process, the average thickness of the layer portion 62 is preferably 10 μm or more.

[0055] <Extension part 63> Each extension portion 63 is disposed in a corresponding communication hole 11 of the metal support 10. Each extension portion 63 is connected to a layer portion 62.

[0056] The porosity of each extension portion 63 can be set to be equal to the porosity of the layer-shaped portion 62. The porosity of each extension portion 63 can be set to be 40% or more and 55% or less. The porosity of each extension portion 63 is calculated by dividing the total area of ​​the pores in each extension portion 63 by the total area of ​​each extension portion 63 on the backscattered electron image described above. Note that, like the porosity of the island-shaped portion 61 described above, the porosity of the extension portion 63 is a value after reduction treatment.

[0057] The average pore diameter in each extension portion 63 can be set to be equal to the average pore diameter in the layer-shaped portion 62. The average pore diameter in each extension portion 63 can be set to be 0.01 μm or more and 1.0 μm or less. The average pore diameter in each extension portion 63 is calculated by arithmetically averaging the circle-equivalent diameters of 50 pores randomly selected from within each extension portion 63 on the backscattered electron image described above.

[0058] Each extension 63 is made of Ni and a ceramic material. Each extension 63 may contain Ni as NiO. The ceramic material may be Y2O3, YSZ, GDC, ScSZ, SDC, CSZ, MSZ, YbSZ, or a mixed material of two or more of these.

[0059] The thickness of each extension portion 63 can be 1 μm or more and 50 μm or less. The thickness of each extension portion 63 is calculated by measuring the maximum distance between the first main surface 12 of the metal support 10 and the tip of the extension portion 63 in the communication hole 11 for each extension portion 63 and arithmetically averaging the measured values.

[0060] <Method for forming hydrogen electrode layer 6> The method for forming the hydrogen electrode layer 6 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.

[0061] For example, when a firing method is used, the porosity and average pore diameter of each of the island portions 61, layer portions 62, and extension portions 63 of the hydrogen electrode layer 6 can be adjusted appropriately by changing the amount and particle size of the pore-forming material added to the paste containing the constituent materials.

[0062] [Electrolyte layer 7] The electrolyte layer 7 is disposed between the hydrogen electrode layer 6 and the oxygen electrode layer 9. In this embodiment, the reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9, and therefore the electrolyte layer 7 is disposed between the hydrogen electrode layer 6 and the reaction prevention layer 8 and is connected to both the hydrogen electrode layer 6 and the reaction prevention layer 8. If the reaction prevention layer 8 is not disposed between the electrolyte layer 7 and the oxygen electrode layer 9, the electrolyte layer 7 is connected to the hydrogen electrode layer 6 and the oxygen electrode layer 9.

[0063] The electrolyte layer 7 covers the hydrogen electrode layer 6 and is connected to the first main surface 12 of the metal support 10. The electrolyte layer 7 has a hydrogen electrode layer side surface 7S that is connected to the hydrogen electrode layer 6.

[0064] The electrolyte layer 7 absorbs the O generated in the hydrogen electrode layer 6. 2-The electrolyte layer 7 is formed of a dense material having oxide ion conductivity. The electrolyte layer 7 can be formed of, for example, YSZ (yttria-stabilized zirconia such as 8YSZ), GDC (gadolinium-doped ceria), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), or LSGM (lanthanum gallate).

[0065] The porosity of the electrolyte layer 7 is not particularly limited, but may be, for example, 0.1% to 7%. The thickness of the electrolyte layer 7 is not particularly limited, but may be, for example, 1 μm to 100 μm. From the viewpoint of workability in the manufacturing process, the thickness of the electrolyte layer 7 is preferably 10 μm or more.

[0066] The method for forming the electrolyte layer 7 is not particularly limited, and a baking method, a spray coating method, a PVD method, a CVD method, or the like can be used.

[0067] [Reaction prevention layer 8] The reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9. The reaction prevention layer 8 is disposed on the opposite side of the electrolyte layer 7 from the hydrogen electrode layer 6. The reaction prevention layer 8 prevents the constituent elements of the electrolyte layer 7 from reacting with the constituent elements of the oxygen electrode layer 9 to form a layer with high electrical resistance.

[0068] The reaction prevention layer 8 is made of an oxide ion conductive material, such as GDC or SDC.

[0069] The porosity of the reaction prevention layer 8 is not particularly limited, but may be, for example, 0.1% to 50%. The thickness of the reaction prevention layer 8 is not particularly limited, but may be, for example, 1 μm to 50 μm. From the viewpoint of workability in the manufacturing process, the thickness of the reaction prevention layer 8 is preferably 10 μm or more.

[0070] The method for forming the reaction prevention layer 8 is not particularly limited, and may be a baking method, a spray coating method, a PVD method, a CVD method, or the like.

[0071] [Oxygen electrode layer 9] The oxygen electrode layer 9 is disposed on the opposite side of the hydrogen electrode layer 6 with respect to the electrolyte layer 7. In this embodiment, the reaction prevention layer 8 is disposed between the electrolyte layer 7 and the oxygen electrode layer 9, and therefore the oxygen electrode layer 9 is connected to the reaction prevention layer 8. If the reaction prevention layer 8 is not disposed between the electrolyte layer 7 and the oxygen electrode layer 9, the oxygen electrode layer 9 would be connected to the electrolyte layer 7.

[0072] The oxygen electrode layer 9 reacts with O 2 transferred from the hydrogen electrode layer 6 through the electrolyte layer 7 in accordance with the chemical reaction of the following formula (5): 2- produces O2 from

[0073] Oxygen electrode layer 9:2O 2- →O2+4e - ···(5)

[0074] The oxygen electrode layer 9 is made of a porous material with oxide ion conductivity and electron conductivity. For example, the oxygen electrode layer 9 can be made of a composite material of one or more of (La,Sr)(Co,Fe)O3, (La,Sr)FeO3, La(Ni,Fe)O3, (La,Sr)CoO3, and (Sm,Sr)CoO3 with an oxide ion conductive material (such as GDC).

[0075] The porosity of the oxygen electrode layer 9 is not particularly limited, but may be, for example, 20% to 60%. The thickness of the oxygen electrode layer 9 is not particularly limited, but may be, for example, 1 μm to 100 μm. From the viewpoint of workability in the manufacturing process, the thickness of the oxygen electrode layer 9 is preferably 10 μm or more.

[0076] The method for forming the oxygen electrode layer 9 is not particularly limited, and may be a firing method, a spray coating method, a PVD method, a CVD method, or the like.

[0077] [Flow path member 30] The flow path member 30 is bonded to the second main surface 13 of the metal support 10. A flow path 30a is formed between the flow path member 30 and the metal support 10. A source gas is supplied to the flow path 30a. The source gas supplied to the flow path 30a is supplied to the hydrogen electrode layer 6 of the cell main body 20 via each communication hole 11 of the metal support 10.

[0078] The flow path member 30 can be made of, for example, an alloy material. The flow path member 30 may be made of the same material as the metal support 10. In this case, the flow path member 30 may be substantially integrated with the metal support 10.

[0079] The flow path member 30 has a frame 31 and an interconnector 32. The frame 31 is an annular member that surrounds the side of the flow path 30a. The frame 31 is joined to the second main surface 13 of the metal support 10. The interconnector 32 is a plate-like member for electrically connecting an external power source or another electrolytic cell to the electrolytic cell 1 in series. The interconnector 32 is joined to the frame 31.

[0080] In this embodiment, the frame body 31 and the interconnector 32 are separate members, but the frame body 31 and the interconnector 32 may be an integrated member.

[0081] (Modification of the embodiment) 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.

[0082] [Variation 1] In the above embodiment, the extending portions 63 of the hydrogen electrode layer 6 are arranged in the communicating holes 11 of the metal support 10, but there may be communicating holes 11 without extending portions 63. Furthermore, the hydrogen electrode layer 6 does not have to have any extending portions 63.

[0083] [Variation 2] In the above embodiment, it has been described with reference to Fig. 2 that the cross-sectional shape of the island-shaped portion 61 may be tapered toward the metal support 10 side or toward the electrolyte layer 7 side. However, the cross-sectional shape of the island-shaped portion 61 can be changed as appropriate in consideration of the ease of the formation method, etc. For example, the cross-sectional shape of the island-shaped portion 61 may be rectangular, or may be drum-shaped with the central portion in the thickness direction projecting in the planar direction.

[0084] [Variation 3] While the above embodiment describes the application of the present invention to an electrolysis cell, the present invention is applicable to electrochemical cells in general, and is particularly effective for fuel cells that use oxide ions or protons as carriers. Note that 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. [Example]

[0085] Examples of the electrochemical cell according to the present invention will be described below, but the present invention is not limited to the examples described below.

[0086] (Examples 1 to 18) The electrolytic cells according to Examples 1 to 18 were prepared as follows: The configuration of the electrolytic cells was as explained in the above embodiment with reference to Figs.

[0087] First, a slurry for the island portions was prepared by mixing YSZ powder, NiO powder, butyral resin, polymethyl methacrylate beads (pore-forming material), plasticizer, dispersant, and solvent. The slurry for the island portions was then printed onto a transfer sheet using a screen printing method to form a molded body for the multiple island portions of the hydrogen electrode layer.

[0088] Next, a layer portion slurry was prepared by mixing GDC powder, NiO powder, butyral resin, polymethyl methacrylate beads (pore-forming material), plasticizer, dispersant, and solvent. The layer portion slurry was then printed onto a transfer sheet using a screen printing method so as to cover the island portion compacts, thereby forming the layer portion compacts of the hydrogen electrode layer. The layer portion slurry contained a smaller amount of pore-forming material and had a smaller particle size than the island portion slurry.

[0089] Next, a metal support made of Fe-Cr-Mn alloy steel with a plurality of through holes formed therein was prepared, and the green bodies for the hydrogen electrode layer (the green bodies for the island portion and the green bodies for the layer portion) were transferred to a first main surface of the metal support.

[0090] Next, 4YSZ powder, butyral resin, plasticizer, dispersant, and solvent were mixed to prepare a slurry for the electrolyte layer, which was then screen-printed onto the green body for the hydrogen electrode layer so as to cover the green body for the island-shaped portion.

[0091] Next, a slurry for the reaction prevention layer was prepared by mixing GDC powder, polyvinyl alcohol, and a solvent, and then the slurry for the reaction prevention layer was printed on the green body of the electrolyte layer by screen printing to form a green body of the reaction prevention layer.

[0092] Next, the molded bodies of the hydrogen electrode layer, electrolyte layer, and reaction prevention layer arranged in that order on the metal support were fired in air (1050°C, 1 hour) to form the hydrogen electrode layer, electrolyte layer, and reaction prevention layer.

[0093] Next, a slurry for the oxygen electrode layer was prepared by mixing (La,Sr)(Co,Fe)O powder, polyvinyl alcohol, and a solvent, and then the slurry for the oxygen electrode layer was printed on the reaction prevention layer using a screen printing method to form a compact for the oxygen electrode layer.

[0094] Next, the compact for the oxygen electrode layer was fired in the air (1000°C, 1 hour) to form the oxygen electrode layer. In this way, the electrolytic cells according to Examples 1 to 18 were completed.

[0095] The thickness of the electrolyte layer, the average thickness of the island portions, and the spacing between the island portions were measured in the cross section along the thickness direction of the electrolytic cells according to Examples 1 to 18. The measurement results are shown in Tables 1 and 2.

[0096] Furthermore, in the electrolytic cells of Examples 1 to 18, the coverage of the island-shaped portions on the hydrogen electrode layer side surface of the electrolyte layer and the average circle-equivalent diameter of the island-shaped portions were measured by observing the hydrogen electrode layer peeled off from the electrolyte layer. The measurement results are shown in Tables 1 and 2. The size of the hydrogen electrode layer side surface of the electrolyte layer in a plan view was 10 mm × 10 mm.

[0097] (Measurement of warpage) The thickness and height of each electrolytic cell were measured, and the value obtained by subtracting the thickness from the height was determined as the amount of warpage. The electrolytic cells according to Examples 1 to 18 all had a uniform amount of warpage of 0.5 mm. In other words, in this example, electrolytic cells with an amount of warpage of 0.5 mm were selected as Examples 1 to 18.

[0098] [Table 1]

[0099] From Table 1, it can be seen that when the thickness of the electrolyte layer is 30 μm or less and the spacing between the island-shaped portions is 0.5 mm or less, the amount of warping of the electrolytic cell can be kept to 0.5 mm or less by setting the coverage rate of the island-shaped portions to 27% or more and the average circular equivalent diameter of the island-shaped portions to 0.16 mm or more.

[0100] Furthermore, Table 1 also shows that the thicker the electrolyte layer is, the larger the coverage rate of the island-shaped portions and the average equivalent circle diameter of the island-shaped portions can be, and therefore the power generation performance can be improved. Furthermore, Table 1 shows that the coverage rate of the islands can be increased as the spacing between the islands decreases.

[0101] [Table 2]

[0102] From Table 2, it can be seen that when the average thickness of the island-shaped portions is 30 μm or less and the spacing between the island-shaped portions is 0.5 mm or less, the amount of warping of the electrolytic cell can be kept to 0.5 mm or less by setting the coverage rate of the island-shaped portions to 37% or more and the average circular equivalent diameter of the island-shaped portions to 0.55 mm or more.

[0103] Furthermore, it is clear from Table 2 that even if the thickness of the hydrogen electrode layer increases, the effect on the coverage rate by the island-shaped portions and the average equivalent circle diameter of the island-shaped portions is small. [Explanation of symbols]

[0104] 1 electrolysis cell 10 Metal support 11 Communication hole 12 First main surface 13 Second main surface 20 Cell body 6 Hydrogen electrode layer 61 Island 61a Island 61b Island 62 Layer 63 Extension 7 Electrolyte layer 8. Reaction prevention layer 9 Oxygen polar layer 30 Flow path member

Claims

1. a metal support having a plurality of communicating holes formed on a main surface; a cell main body portion disposed on the main surface; Equipped with The cell main body is a hydrogen electrode layer disposed on the main surface and covering the plurality of communicating holes; an oxygen electrode layer; an electrolyte layer disposed between the hydrogen electrode layer and the oxygen electrode layer; and The hydrogen electrode layer is a plurality of island-shaped portions connected to the electrolyte layer; a layer portion covering the plurality of island portions and connected to the electrolyte layer; Including, the porosity of each of the plurality of island portions is lower than the porosity of the layer portion; Electrochemical cell.

2. the plurality of island-shaped portions include island-shaped portions that are tapered toward the metal support in a cross section along the thickness direction; 10. The electrochemical cell of claim 1.

3. the plurality of island-shaped portions include island-shaped portions that are tapered toward the electrolyte layer side in a cross section along the thickness direction; 3. The electrochemical cell of claim 1 or 2.

4. a central portion of the island-shaped portion in a surface direction does not overlap with the communication hole in a thickness direction; 10. The electrochemical cell of claim 1.

5. when the thickness of the electrolyte layer is 30 μm or less and the spacing between the plurality of island-shaped portions is 0.5 mm or less, the coverage of the hydrogen electrode layer side surface of the electrolyte layer by the plurality of island-shaped portions is 27% or more, and the average circle-equivalent diameter of the plurality of island-shaped portions in a plan view of the hydrogen electrode layer side surface of the electrolyte layer is 0.16 mm or more; 10. The electrochemical cell of claim 1.

6. When the average thickness of the plurality of island-shaped portions is 30 μm or less and the interval between the plurality of island-shaped portions is 0.5 mm or less, the coverage of the hydrogen electrode layer side surface of the electrolyte layer by the plurality of island-shaped portions is 37% or more, and the average circle-equivalent diameter of the plurality of island-shaped portions in a plan view of the hydrogen electrode layer side surface of the electrolyte layer is 0.55 mm or more.

10. The electrochemical cell of claim 1.

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