Solid oxide fuel cell and method for manufacturing the same

Abstract

To provide a solid oxide fuel cell capable of reducing gas diffusion resistance and a method for manufacturing the same.SOLUTION: A solid oxide fuel cell has a metal substrate having a plurality of through holes in the thickness direction, a porous metal layer provided on the metal substrate and mainly composed of metal, and an anode provided on the porous metal layer, and grooves connecting the plurality of through holes are formed on the main surface on the porous metal layer side of the metal substrate.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a solid oxide fuel cell and a method for producing the same. [Background technology]

[0002] Solid oxide fuel cells are attracting attention as a CO2 reduction technology due to their high power generation efficiency. In recent years, metal-supported solid oxide fuel cells, which are supported by a metal substrate, have been developed for use in automobiles and other applications (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-158026 [Patent Document 2] Special Publication No. 2004-512651 [Overview of the project] [Problems that the invention aims to solve]

[0004] Patent documents 1 and 2 disclose a method of printing electrodes by drilling holes in a metal substrate support in order to ensure the gas permeability of the cell. However, in the cell, a difference in gas diffusion may occur between the parts located on the substrate holes and the parts not located on the substrate holes, which may lead to increased gas diffusion resistance.

[0005] This invention has been made in view of the above problems, and aims to provide a solid oxide fuel cell and a method for manufacturing the same that can reduce gas diffusion resistance. [Means for solving the problem]

[0006] The solid oxide fuel cell according to the present invention comprises a metal substrate having a plurality of through holes in the thickness direction, a porous metal layer provided on the metal substrate and mainly composed of metal, and an anode provided on the porous metal layer, wherein grooves connecting the plurality of through holes are formed on the main surface of the metal substrate on the porous metal layer side.

[0007] In the solid oxide fuel cell described above, the thickness of the metal substrate may be 0.2 mm or more and 1 mm or less.

[0008] In the above-described solid oxide fuel cell, the metal substrate may be ferritic stainless steel.

[0009] In the solid oxide fuel cell described above, the diameter of the through-hole may be 0.1 mm or more and 6 mm or less.

[0010] In the solid oxide fuel cell described above, the pitch of the multiple through-holes may be 1.2 times or more and 5 times or less the diameter of the through-holes.

[0011] In the solid oxide fuel cell described above, the width of the groove may be 1 / 10 or more and 1 / 2 or less of the diameter of the through hole.

[0012] In the solid oxide fuel cell described above, the depth of the groove may be 1 / 10 or more and 1 / 2 or less of the thickness of the metal substrate.

[0013] In the solid oxide fuel cell described above, the multiple through holes in the metal substrate may be arranged at each of the multiple grid points.

[0014] In the solid oxide fuel cell described above, the through-hole may be connected to the four nearest through-holes by the groove.

[0015] In the solid oxide fuel cell described above, the through-holes may be connected by grooves to the four nearest through-holes and to the four nearest through-holes after the four aforementioned through-holes.

[0016] The manufacturing method of the solid oxide fuel cell according to the present invention includes a metal substrate having a plurality of through holes in the thickness direction and grooves formed on one main surface to connect the plurality of through holes, and a half cell provided with an anode on a porous metal layer mainly composed of metal. The method further includes a step of pressure sintering the anode side of the half cell against the one main surface of the metal substrate.

Effect of the Invention

[0017] According to the present invention, it is possible to provide a solid oxide fuel cell capable of reducing gas diffusion resistance and a method for manufacturing the same.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic cross-sectional view illustrating the stacked structure of the fuel cell. [Figure 2] It is an enlarged cross-sectional view illustrating details of the porous metal layer, the mixed layer, and the anode. [Figure 3] It is a perspective view of the metal substrate. [Figure 4] (a) and (b) are diagrams illustrating the diameter and pitch of the through holes. [Figure 5] It is a diagram illustrating the main surface on the anode side of the metal substrate. [Figure 6] It is a cross-sectional view taken along the line A-A of FIG. 5. [Figure 7] It is a diagram illustrating the main surface on the anode side of the metal substrate. [Figure 8] It is a diagram illustrating the main surface on the anode side of the metal substrate. [[ID= thirty-nine]] [Figure 9] It is a diagram illustrating the main surface on the anode side of the metal substrate. <舍 [Figure 10] (a) and (b) are cross-sectional views of a plane perpendicular to the direction in which the groove extends. [Figure 11] It is a diagram illustrating the flow of the manufacturing method of the fuel cell.

Embodiments for Carrying Out the Invention

[0019] The embodiments will be described below with reference to the drawings.

[0020] Figure 1 is a schematic cross-sectional view illustrating a stacked structure of a solid oxide fuel cell 100. As illustrated in Figure 1, the fuel cell 100 has, for example, a structure in which a porous metal layer 10, a mixed layer 20, an anode 30, an electrolyte layer 40, an intermediate layer 50, and a cathode 60 are stacked in this order on a metal substrate 5. Multiple fuel cells 100 may be stacked to form a fuel cell stack. The metal substrate 5 has one or more through holes 51 that penetrate in the thickness direction.

[0021] The electrolyte layer 40 is a solid oxide electrolyte layer mainly composed of a solid oxide having oxide ion conductivity, and is a dense layer with gas impermeability. Preferably, the electrolyte layer 40 is mainly composed of scandia-yttria stabilized zirconium oxide (ScYSZ), YSZ (yttria stabilized zirconium oxide), or GDC (Gd-doped ceria) in which gadolinium (Gd) is doped into CeO2. When using ScYSZ, the oxide ion conductivity is highest when the concentration of Y2O3 + Sc2O3 is between 6 mol% and 15 mol%, and it is desirable to use a material with this composition. Furthermore, the thickness of the electrolyte layer 40 is preferably 20 μm or less, and more preferably 10 μm or less. While a thinner electrolyte is preferable, a thickness of 1 μm or more is desirable to prevent gas leakage from both sides during manufacturing.

[0022] Cathode 60 is an electrode that has electrode activity as a cathode and possesses electronic conductivity and oxide ion conductivity. For example, cathode 60 mainly consists of a ceramic material that has electronic conductivity and oxide ion conductivity. As the ceramic material, for example, LaCoO3-based materials, LaMnO3-based materials, LaFeO3-based materials, etc., can be used. For example, as a LaCoO3-based material, LSC (lanthanum strontium cobaltite) can be used. LSC is LaCoO3 doped with Sr (strontium).

[0023] The intermediate layer 50 is a reaction prevention layer mainly composed of components that prevent the reaction between the electrolyte layer 40 and the cathode 60. The constituent materials of the intermediate layer 50 are different from those of the electrolyte layer 40. The intermediate layer 50 has oxide ion conductivity but does not have electrode activity as a cathode. For example, the intermediate layer 50 has a structure in which additives are added to ceria (CeO2). The additives are not particularly limited. For example, the intermediate layer 50 may be GDC (e.g., Ce 0.8 Gd 0.2 O 2-x ) are the main components. For example, if the electrolyte layer 40 contains ScYSZ and the cathode 60 contains LSC, the intermediate layer 50 prevents the following reactions. Sr + ZrO2 → SrZrO3 La+ZrO3→La2Zr2O7

[0024] Figure 2 is an enlarged cross-sectional view illustrating details of the porous metal layer 10, the mixed layer 20, and the anode 30.

[0025] The porous metal layer 10 is a gas-permeable member capable of supporting the mixed layer 20, the anode 30, and the electrolyte layer 40. Therefore, the porous metal layer 10 also functions as a support for the mixed layer 20, the anode 30, and the electrolyte layer 40. The porous metal layer 10 is a porous metal having multiple voids, such as a porous Fe-Cr alloy. Details of the material of the porous metal layer 10 will be described later.

[0026] The anode 30 is an electrode that has electrode activity as an anode and has a porous body (electrode skeleton) made of ceramic material. The porous body does not contain any metal components. In this configuration, the decrease in the porosity of the anode due to the coarsening of the metal components is suppressed during firing in a high-temperature reducing atmosphere. In addition, alloying of the porous metal layer 10 with the metal components is suppressed, and the deterioration of catalytic function is suppressed.

[0027] The porous material of the anode 30 has both electronic conductivity and oxide ion conductivity. The porous material of the anode 30 contains an electronically conductive ceramic 31. As the electronically conductive ceramic 31, for example, a perovskite-type oxide represented by the compositional formula ABO3 can be used, in which the A site is at least one selected from the group Ca, Sr, Ba, and La, and the B site is at least one selected from Ti and Cr. The molar ratio of the A site to the B site may be B≧A. Specifically, as the electronically conductive ceramic 31, materials such as LaCrO3-based materials and SrTiO3-based materials can be used.

[0028] Furthermore, the porous body of the anode 30 contains oxide ion conductive ceramics 32. The oxide ion conductive ceramics 32 are such as ScYSZ. For example, it is preferable to use ScYSZ having a composition range of 5 mol% to 16 mol% of scandia (Sc2O3) and 1 mol% to 3 mol% of yttria (Y2O3). ScYSZ with a combined amount of scandia and yttria of 6 mol% to 15 mol% is even more preferable, because the oxide ion conductivity is highest in this composition range. The oxide ion conductive ceramics 32 are, for example, materials with an oxide ion transport fraction of 99% or more. GDC may also be used as the oxide ion conductive ceramics 32. In the example in Figure 2, the same solid oxide contained in the electrolyte layer 40 is used as the oxide ion conductive ceramics 32.

[0029] As illustrated in Figure 2, in the anode 30, for example, an electron-conducting ceramic 31 and an oxide ion-conducting ceramic 32 form a porous body. Multiple voids are formed by this porous body. The anode catalyst is supported on the surface of the porous body in the void portions. Therefore, in the spatially continuous porous body, multiple anode catalysts are spatially dispersed. It is preferable to use a composite catalyst as the anode catalyst. For example, it is preferable that an oxide ion-conducting ceramic 33 and a catalyst metal 34 are supported on the surface of the porous body as a composite catalyst. As the oxide ion-conducting ceramic 33, for example, Y-doped BaCe 1-x Zr x O3(BCZY, x=0~1), Y-doped SrCe 1-x Zr x O3 (SCZY, x=0~1), Sr-doped LaScO3 (LSS), GDC, etc. can be used. Ni, etc., can be used as the catalyst metal 34. The oxide ion conductive ceramic 33 may have the same composition as the oxide ion conductive ceramic 32, or it may have a different composition. The metal that functions as the catalyst metal 34 may be in the form of a compound when no power is being generated. For example, Ni may be in the form of NiO (nickel oxide). During power generation, these compounds are reduced by the reducing fuel gas supplied to the anode 30 and take the form of a metal that functions as an anode catalyst. For example, the D50% particle size of the anode catalyst is 10 nm or more and 1 μm or less.

[0030] Furthermore, since the fuel cell 100 generates electricity at high temperatures, for example, 600°C to 900°C, if the ceramic particles constituting the porous body of the anode 30 are too small, the ceramic particles may sinter at the power generation temperature, potentially resulting in insufficient void space for gas flow. Therefore, it is preferable to set a lower limit on the D50% diameter of the ceramic particles constituting the porous body of the anode 30 in cross-section. For example, the D50% diameter of the ceramic particles constituting the porous body of the anode 30 is preferably 0.5 μm or larger, more preferably 0.8 μm or larger, and even more preferably 1 μm or larger. The ceramic particles constituting the porous body of the anode 30 refer to the electron-conducting ceramics 31 and the oxide ion-conducting ceramics 32.

[0031] On the other hand, if the ceramic particles constituting the porous body of the anode 30 are too large, the specific surface area decreases, reducing the three-phase interface that contributes to the electrode reaction, which may lead to a decrease in power generation characteristics. Therefore, it is preferable to set an upper limit on the D50% diameter of the ceramic particles constituting the porous body of the anode 30 in cross-section. For example, the D50% diameter of the ceramic particles constituting the porous body of the anode 30 is preferably 3 μm or less, more preferably 2.5 μm or less, and even more preferably 2 μm or less.

[0032] If the anode 30 is too thin, the three-phase interface that contributes to the electrode reaction will decrease, which may reduce the power generation characteristics. Therefore, it is preferable to set a lower limit on the thickness of the anode 30. For example, the thickness of the anode 30 is preferably 1 μm or more, more preferably 2 μm or more, and even more preferably 3 μm or more.

[0033] On the other hand, if the anode 30 is too thick, the gas used in the power generation reaction must diffuse over a longer distance. To suppress this gas diffusion resistance, it is preferable to set an upper limit on the thickness of the anode 30. For example, the thickness of the anode 30 is preferably 15 μm or less, more preferably 12 μm or less, and even more preferably 10 μm or less.

[0034] The thickness of anode 30 can be obtained, for example, by calculating the average of the thicknesses of 10 different points.

[0035] If the porosity of the anode 30 as a whole is too low, the fuel gas may not react sufficiently, which could lead to a decrease in power generation performance. Therefore, it is preferable to set a lower limit on the porosity of the anode 30 as a whole. For example, the porosity of the anode 30 as a whole is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more.

[0036] On the other hand, if the porosity of the anode 30 as a whole is too high, the adhesion between layers will decrease, and there is a risk of delamination. Therefore, it is preferable to set an upper limit on the porosity of the anode 30 as a whole. For example, the porosity of the anode 30 as a whole is preferably 80% or less, more preferably 75% or less, and even more preferably 70% or less.

[0037] The void ratio of the anode 30 as a whole can be obtained by calculating the ratio of the total area of ​​each void to the total area of ​​the anode 30 in a cross-sectional photograph.

[0038] In the anode 30, ion-electron mixed conductive ceramics may be used instead of the electron-conducting ceramics 31 and the oxide ion-conducting ceramics 32.

[0039] The mixed layer 20 contains a metal material 21 and a ceramic material 22. In the mixed layer 20, the metal material 21 and the ceramic material 22 are randomly mixed. Therefore, a structure is not formed in which layers of metal material 21 and layers of ceramic material 22 are stacked. Multiple voids are also formed in the mixed layer 20. The metal material 21 is not particularly limited as long as it is a metal. In the example in Figure 2, the same metal material as in the porous metal layer 10 is used as the metal material 21. As the ceramic material 22, electron-conducting ceramics 31, oxide ion-conducting ceramics 32, etc. can be used. For example, as the ceramic material 22, ScYSZ, GDC, SrTiO3-based materials, LaCrO3-based materials, etc. can be used. SrTiO3-based materials and LaCrO3-based materials have high electron conductivity, so the ohmic resistance in the mixed layer 20 can be reduced. In addition, ion-electron mixed conductive ceramics may be used instead of electron-conducting ceramics 31 and oxide ion-conducting ceramics 32.

[0040] As illustrated in Figure 2, in the mixed layer 20, for example, a metal material 21 and a ceramic material 22 form a porous body. Multiple voids are formed by this porous body. Multiple reforming catalysts are supported on the surface of the porous body in the void portions. It is preferable to use a composite catalyst as the reforming catalyst. For example, as a composite catalyst, oxide ion conductive ceramics 23 and a catalyst metal 24 are supported on the surface of the porous body. Therefore, in the porous body formed spatially continuous by the metal material 21 and the ceramic material 22, multiple oxide ion conductive ceramics 23 and catalyst metals 24 are spatially dispersed. The reforming catalyst is not particularly limited as long as it can reform hydrocarbon gas into hydrogen gas. As combinations of catalyst metal 24 and oxide ion conductive ceramics 23, for example, a combination of Ni and GDC, a combination of Ni and YSZ, or a combination of Ni and SDC (Samaria-doped ceria) can be used. Ni may take the form of NiO (nickel oxide). During power generation, these compounds are reduced by the reducing fuel gas supplied to the anode 30 and take the form of a metal that functions as a reforming catalyst. It is preferable that the oxide ion conductive ceramic 23 is made of the same material as the oxide ion conductive ceramic 33. It is preferable that the catalyst metal 24 is made of the same material as the catalyst metal 34.

[0041] The fuel cell 100 generates electricity through the following process: An oxidizing gas containing oxygen, such as air, is supplied to the cathode 60. In the cathode 60, oxygen reacts with electrons supplied from an external electrical circuit to form oxide ions. The oxide ions conduct through the electrolyte layer 40 and move towards the anode 30.

[0042] Meanwhile, fuel gas containing hydrocarbon gas, water vapor, etc., is introduced into the metal substrate 5. The fuel gas reaches the mixing layer 20 through the through holes 51 and the voids in the porous metal layer 10. The fuel gas is reformed into a reformed gas containing hydrogen gas by the catalytic action of the catalyst metal 24 in the mixing layer 20. The reforming reaction can be represented, for example, by the following formula. 2CH4 + 2H2O → CO + 6H2 + CO2

[0043] The reformed gas reaches the anode 30 through the voids in the mixing layer 20. The hydrogen that reaches the anode 30 releases electrons and reacts with oxide ions that conduct through the electrolyte layer 40 from the cathode 60 side to form water (H2O). The released electrons are extracted to the outside by an external electrical circuit. The extracted electrons perform electrical work before being supplied to the cathode 60. Through these actions, electricity is generated.

[0044] In the above power generation reaction, catalyst metal 24 functions as a catalyst for the reforming reaction. Catalyst metal 34 functions as a catalyst in the reaction between hydrogen and oxide ions. Electron-conductive ceramics 31 are responsible for the conduction of electrons obtained by the reaction between hydrogen and oxide ions. Oxide ion-conductive ceramics 32 are responsible for the conduction of oxide ions that have reached the anode 30 from the electrolyte layer 40.

[0045] Thus, in the fuel cell 100 according to this embodiment, fuel gas reforming and power generation are performed inside the fuel cell 100.

[0046] Figure 3 is a perspective view of the metal substrate 5. The material of the metal substrate 5 is not particularly limited, but examples include austenitic stainless steel, ferritic stainless steel, etc., such as SUS430, SUS304, and Crofer22. In this embodiment, ferritic stainless steel is used as an example. The thickness of the metal substrate 5 is, for example, 0.2 mm or more and 1 mm or less. It is preferable that the through holes 51 are voids and do not contain any substances other than gas, but other components may partially extend into them. The presence of through holes 51 improves the permeability of the fuel gas. However, if the through holes 51 are too small, the metal substrate 5 may not achieve sufficient permeability. Therefore, in this embodiment, it is preferable to set a lower limit on the size of the through holes 51. Specifically, it is preferable that the diameter of the through holes 51 in the in-plane direction of the metal substrate 5 be 0.1 mm or more. On the other hand, if the through holes 51 are too large, the paste for forming the support 10 may enter the through holes 51, and sufficient permeability may not be obtained. Therefore, in this embodiment, it is preferable to set an upper limit on the size of the through hole 51. Specifically, it is preferable to set the diameter of the through hole 51 to 6 mm or less.

[0047] For example, as illustrated in Figure 4(a), the through-hole 51 has a circular shape when viewed from above with respect to the metal substrate 5. In a plan view with respect to the metal substrate 5, the circular shape has a maximum length L of a diameter of 0.1 mm or more and 6 mm or less. As illustrated in Figure 4(b), the through-hole 51 may have other shapes, such as a rectangle, when viewed from above with respect to the metal substrate 5. In this case, the through-hole 51 has a maximum length L of a diagonal of 0.1 mm or more and 6 mm or less. Thus, the diameter of the through-hole 51 refers to the maximum length when viewed from above with respect to the metal substrate 5.

[0048] From the viewpoint of obtaining good breathability, the diameter of the through-hole 51 is preferably 0.1 mm or more, and more preferably 1 mm or more. Furthermore, from the viewpoint of preventing the paste for forming the porous metal layer 10 from entering the through-hole 51, the diameter of the through-hole 51 is preferably 6 mm or less, and more preferably 4 mm or less.

[0049] If a plurality of through holes 51 are provided in the metal substrate 5, the average value of the diameter of each through hole 51 is preferably 0.1 mm or more, preferably 1 mm or more, more preferably 1.5 mm or more, preferably 6 mm or less, preferably 4 mm or less, and more preferably 3 mm or less.

[0050] In this embodiment, as illustrated in Figures 4(a) and 4(b), the distance between through holes 51 (pitch P) refers to the distance between the center O of a predetermined through hole 51 and the center O of an adjacent through hole 51, when focusing on a predetermined through hole 51.

[0051] In this embodiment, since a porous support 10 is provided on the metal substrate 5, gas permeability is achieved while improving the adhesion between the metal substrate 5 and the mixed layer 20. Furthermore, since a mixed layer 20 comprising both metal and ceramic components is provided between the support 10 and the anode 30, the adhesion between the support 10 and the anode 30 is improved. Therefore, the adhesion between the metal substrate 5 and the anode 30 is improved.

[0052] As described above, the fuel cell 100 according to this embodiment can achieve both good adhesion between the metal substrate 5 and the anode 30 and good air permeability of the metal substrate 5.

[0053] However, in the fuel cell 100, a difference in gas diffusivity may occur between the portion located on the through-hole 51 and the portion not located on the through-hole 51, potentially leading to increased gas diffusion resistance. Therefore, the fuel cell 100 according to this embodiment has a configuration that can reduce gas diffusion resistance.

[0054] Figure 5 is a diagram illustrating the main surface of the metal substrate 5 on the anode 30 side. Figure 6 is a cross-sectional view taken along line AA of Figure 5. As illustrated in Figures 5 and 6, grooves 52 connecting multiple through holes 51 are formed on the main surface of the metal substrate 5 on the anode 30 side. With this configuration, gas diffuses through the grooves 52, improving gas diffusivity in areas not located on the through holes 51. This suppresses gas diffusion resistance.

[0055] The number of grooves 52 connected to each through-hole 51 is not particularly limited, but a larger number is preferable. For example, as illustrated in Figure 5, when each through-hole 51 is located at each grid point, each through-hole 51 may be connected to the four nearest through-holes 51 by four grooves 52.

[0056] Alternatively, as illustrated in Figure 7, when each through-hole 51 is located at each grid point, each through-hole 51 may be connected to the two nearest through-holes 51 by two grooves 52.

[0057] Alternatively, as illustrated in Figure 8, when each through-hole 51 is located at each grid point, each through-hole 51 may be connected to the next four nearest through-holes 51b and four grooves 52, following the four nearest through-holes 51a.

[0058] Alternatively, as illustrated in Figure 9, when each through-hole 51 is located at each grid point, each through-hole 51 may be connected to the four nearest through-holes 51a and the next four nearest through-holes 51b by eight grooves 52.

[0059] Figures 10(a) and 10(b) are cross-sectional views taken in a plane perpendicular to the direction in which the groove 52 extends. As illustrated in Figure 10(a), the groove 52 may have a semicircular or arc-shaped cross-section. Alternatively, as illustrated in Figure 10(b), the groove 52 may have a rectangular cross-section.

[0060] The width W of the groove 52 is the distance from the point where the recess begins on the main surface of the metal substrate 5 where the groove 52 is formed, to the point where the recess ends, in a cross-section of a plane perpendicular to the direction in which the groove 52 extends. The depth D of the groove 52 is the distance from the deepest point in the thickness direction of the metal substrate 5 to the main surface of the metal substrate 5 where the groove 52 is formed.

[0061] If the pitch P between through holes 51 in the plane of the metal substrate 5 is long, sufficient gas diffusion may not be obtained. Therefore, it is preferable to set an upper limit on the pitch P. For example, the pitch P is preferably 5 times or less the diameter of the predetermined through hole 51, more preferably 4 times or less, and even more preferably 3 times or less.

[0062] When three or more through holes 51 are provided in the metal substrate 5, the average value of the distance between the centers of adjacent through holes 51 (pitch P) is preferably five times or less the diameter of each through hole 51, more preferably four times or less, and even more preferably three times or less.

[0063] On the other hand, if the pitch P is too short, the strength of the metal substrate 5 decreases, and there is a risk of it cracking when assembling the fuel cell stack. Therefore, it is preferable to set a lower limit on the pitch P between the through holes 51. The pitch P is preferably 1.2 times or more the diameter of each through hole 51, more preferably 1.5 times or more, and even more preferably 2 times or more.

[0064] When three or more through holes 51 are provided in the metal substrate 5, the average value of the pitch P is preferably 1.2 times or more the diameter of each through hole 51, more preferably 1.5 times or more, and even more preferably 2 times or more.

[0065] If the width W of the groove 52 is small, sufficient gas diffusion may not be obtained. Therefore, it is preferable to set a lower limit on the width W. For example, the width W is preferably 1 / 10 or more of the diameter of the through hole 51, more preferably 1 / 7 or more, and even more preferably 1 / 5 or more.

[0066] If the width W of the groove 52 is large, there is a risk of a decrease in the strength of the metal substrate 5. Therefore, it is preferable to set an upper limit on the width W. For example, the width W is preferably 1 / 2 or less of the diameter of the through hole 51, more preferably 1 / 3 or less, and even more preferably 1 / 4 or less.

[0067] If the depth D of the groove 52 is small, sufficient gas diffusion may not be obtained. Therefore, it is preferable to set a lower limit on the depth D. For example, the depth D is preferably 1 / 10 or more of the thickness of the metal substrate 5, more preferably 1 / 7 or more, and even more preferably 1 / 5 or more.

[0068] If the depth D of the groove 52 is large, there is a risk of a decrease in the strength of the metal substrate 5. Therefore, it is preferable to set an upper limit on the depth D. For example, the depth D is preferably 1 / 2 or less of the thickness of the metal substrate 5, more preferably 1 / 3 or less, and even more preferably 1 / 4 or less.

[0069] The thickness of the metal substrate 5 is, for example, 0.1 mm to 1 mm, 0.2 mm to 0.8 mm, or 0.3 mm to 0.6 mm. Furthermore, from the viewpoint of maintaining sufficient support strength, it is preferable that the thickness of the metal substrate 5 is greater than that of the porous metal layer 10.

[0070] The manufacturing method of the fuel cell 100 will be described below. Figure 11 is a diagram illustrating the flow of the manufacturing method of the fuel cell 100.

[0071] (Metal substrate manufacturing process) A metal substrate 5 is prepared, and through holes are formed at regular intervals by machining. Either ferritic stainless steel or austenitic stainless steel may be used, but for example, ferritic stainless steel is used. Through holes 51 are machined into the metal substrate 5 at regular intervals, and through holes 51 are also formed at each grid point. Furthermore, grooves 52 connecting the through holes 51 are formed by machining.

[0072] (Process for manufacturing porous metal layer materials) As a material for porous metal layers, metal powder (for example, with a particle size of 10 μm to 100 μm), plasticizer (for example, adjusted from 1 wt% to 6 wt% to adjust the adhesion of the sheet), solvent (toluene, 2-propanol (IPA), 1-butanol, terpineol, butyl acetate, ethanol, etc., 20 wt% to 30 wt% depending on viscosity), loss agent (organic matter), and binder (PVB, acrylic resin, ethylcellulose, etc.) are mixed to form a slurry. The material for porous metal layers is used as a material for forming the porous metal layer 10. The volume ratio of organic components (loss agent, binder solids, plasticizer) to metal powder is, for example, in the range of 1:1 to 20:1, and the amount of organic components is adjusted according to the porosity.

[0073] (Process for preparing materials for mixed layers) As a material for the mixed layer, ceramic material powder (e.g., particle size 100 nm to 10 μm), which is the raw material for ceramic material 22, small particle size metal material powder (e.g., particle size 1 μm to 10 μm), which is the raw material for metal material 21, solvent (toluene, 2-propanol (IPA), 1-butanol, terpineol, butyl acetate, ethanol, etc., 20 wt% to 30 wt% depending on viscosity), plasticizer (e.g., adjusted from 1 wt% to 6 wt% to adjust the adhesion of the sheet), waste material (organic matter), and binder (PVB, acrylic resin, ethyl cellulose, etc.) are mixed to form a slurry. The volume ratio of organic components (waste material, binder solids, plasticizer) to ceramic material powder and metal material powder is, for example, in the range of 1:1 to 5:1, and the amount of organic components is adjusted according to the porosity. The pore size of the voids is controlled by adjusting the particle size of the waste material. The ceramic material powder may contain both an electronically conductive material powder and an oxide ion conductive material powder. In this case, the volume ratio of the electronically conductive material powder to the oxide ion conductive material powder is preferably in the range of 1:9 to 9:1. Furthermore, even if an electrolyte material such as ScYSZ or GDC is used instead of the electronically conductive material, there is no delamination at the interface, and cells can be fabricated. However, from the viewpoint of reducing ohmic resistance, it is preferable to mix the electronically conductive material with metal powder.

[0074] (Process for preparing materials for anodes) As the anode material, a slurry is prepared by mixing ceramic material powder constituting the electrode framework, a solvent (toluene, 2-propanol (IPA), 1-butanol, terpineol, butyl acetate, ethanol, etc., 20 wt% to 30 wt% depending on viscosity), a plasticizer (for example, adjusted from 1 wt% to 6 wt% to adjust the adhesion of the sheet), a waste material (organic substance), and a binder (PVB, acrylic resin, ethylcellulose, etc.). As the ceramic material powder constituting the electrode framework, electron conductive material powder (for example, particle size 100 nm to 10 μm), which is the raw material for electron conductive ceramics 31, or oxide ion conductive material powder (for example, particle size 100 nm to 10 μm), which is the raw material for oxide ion conductive ceramics 32, may be used. The volume ratio of organic components (waste material, binder solids, plasticizer) to electron conductive material powder is, for example, in the range of 1:1 to 5:1, and the amount of organic components is adjusted according to the porosity. Furthermore, the pore size of the voids is controlled by adjusting the particle size of the lost material. The volume ratio of the electronically conductive material powder to the oxide ion conductive material powder is, for example, in the range of 1:9 to 9:1.

[0075] (Process for preparing the electrolyte layer material) As a material for the electrolyte layer, an oxide ion conductive material powder (e.g., ScYSZ, YSZ, GDC, etc., with a particle size of 10 nm to 1000 nm), a solvent (toluene, 2-propanol (IPA), 1-butanol, terpineol, butyl acetate, ethanol, etc., 20 wt% to 30 wt% depending on viscosity), a plasticizer (e.g., adjusted from 1 wt% to 6 wt% to adjust the adhesion of the sheet), and a binder (PVB, acrylic resin, ethyl cellulose, etc.) are mixed to form a slurry. The volume ratio of organic components (binder solids, plasticizer) to oxide ion conductive material powder is, for example, in the range of 6:4 to 3:4.

[0076] (Firing process) First, a porous metal green sheet is prepared by coating a porous metal layer material onto a PET (polyethylene terephthalate) film. A mixed layer green sheet is prepared by coating a mixed layer material onto another PET film. An anode green sheet is prepared by coating an anode material onto another PET film. An electrolyte layer green sheet is prepared by coating an electrolyte layer material onto another PET film. For example, multiple porous metal green sheets, one mixed layer green sheet, one anode green sheet, and one electrolyte layer green sheet are stacked in order and cut to a predetermined size. After that, the oxygen partial pressure is 10 -20 The half-cell is fired in a reducing atmosphere below atm at a temperature range of approximately 1100°C to 1300°C. This yields a half-cell comprising a porous metal layer 10, a mixed layer 20, an electrode framework of an anode 30, and an electrolyte layer 40. These porous metal layer 10, mixed layer 20, electrode framework of an anode 30, and electrolyte layer 40 are sintered bodies. The reducing gas flowing into the furnace may be a gas in which H2 (hydrogen) is diluted with a non-combustible gas (such as Ar (argon), He (helium), N2 (nitrogen)), or it may be a gas of 100% H2. For safety reasons, it is preferable to set an upper limit up to the explosion limit. For example, in the case of a mixed gas of H2 and Ar, the concentration of H2 is preferably 4% by volume or less.

[0077] (Adhesion process to metal substrate) The half-cell is placed on the machined metal substrate 5, and pressure firing is performed using a hot press in an inert gas atmosphere or a reducing atmosphere. Through firing, the materials of the porous metal layer 10 and the metal substrate 5 diffuse and adhere to each other. The firing temperature during pressure firing is preferably 1100°C or higher, more preferably 1200°C or higher, and even more preferably 1300°C or higher.

[0078] (Anode impregnation process) Next, the raw materials for the oxide ion conductive ceramics 33 and the catalyst metal 34 are impregnated into the electrode framework of the anode 30. For example, nitrates or chlorides of Zr, Y, Sc, Ce, Gd, and Ni are dissolved in water or alcohols (ethanol, 2-propanol, methanol, etc.) so that Gd-doped ceria or Sc,Y-doped zirconia and Ni are produced when fired at a predetermined temperature in a reducing atmosphere. The half-cells are then impregnated, dried, and the heat treatment is repeated the required number of times.

[0079] (Intermediate layer formation process) The intermediate layer 50 is formed by depositing oxide ion conductive ceramics (such as GDC or SDC) contained in the intermediate layer 50 onto the electrolyte layer 40, for example, by PVD (physical vapor deposition) or PLD (pulsed laser ablation deposition).

[0080] (Process for preparing cathode materials) For the cathode material, conductive ceramic powder such as lanthanum strontium cobaltite (LSC: LaSrCoO3) is mixed with a solvent (toluene, 2-propanol (IPA), 1-butanol, terpineol, butyl acetate, ethanol, etc., 20 wt% to 30 wt% depending on viscosity), a plasticizer (for example, adjusted from 1 wt% to 6 wt% to adjust the adhesion of the sheet), and a binder (PVB, acrylic resin, ethyl cellulose, etc.) to form a slurry. The volume ratio of organic components (binder solids, plasticizer) to LSC powder is, for example, in the range of 6:4 to 1:4.

[0081] (Cathode formation process) The cathode material, prepared by screen printing, is printed onto the intermediate layer. Then, it is fired at 1000°C in a neutral atmosphere such as nitrogen. Through these steps, the oxide fuel cell is completed.

[0082] According to the manufacturing method according to this embodiment, instead of printing and firing the electrode paste on the metal substrate, the half cell is fired and then adhered to the metal substrate 5. In this case, clogging of the through holes 51 by the electrode paste can be suppressed, so that the gas diffusion resistance can be reduced.

[0083] Further, after the adhesion step, since the oxide ion conductive ceramic 33 and the catalyst metal 34 are impregnated, it is possible to prevent the catalyst from reacting with other members during the adhesion step.

Example

[0084] A fuel cell 100 was fabricated according to the manufacturing method according to the above embodiment.

[0085] (Example 1) Through holes with a diameter of Φ3 mm were fabricated on the metal substrate by machining at a pitch (center-to-center distance) of 10 mm. Each through hole was arranged at a lattice point. As illustrated in FIG. 9, each through hole was processed so as to be connected by eight grooves to the four nearest through holes and the four next-nearest through holes. The width W of each groove was 1 mm and the depth D was 0.2 mm.

[0086] A half cell having a porous metal layer, a mixed layer, and an anode was placed on the processed metal substrate and pressure-fired to adhere the metal substrate and the half cell. The anode catalyst was generated by impregnating, drying, and heat-treating the anode porous body of the half cell with a metal substrate with a nitrate solution of Zr, Y, Sc, Ce, Gd, and Ni. An intermediate layer was formed on the electrolyte layer by PVD. Using the paste of the cathode LSC, after screen printing on the intermediate layer, it was fired at 1000° C. in a N2 atmosphere to complete the full cell. Power generation evaluation was performed using the completed full cell, and the gas diffusion resistance on the low-frequency side separated by impedance measurement was 0.11 Ω·cm 2 and became low. This is presumably because the gas diffusibility was improved by forming grooves in addition to the through holes in the metal substrate.

[0087] (Example 2) Through holes with a diameter of Φ3 mm were fabricated on a metal substrate at a pitch of 10 mm (center-to-center distance) using machining. Each through hole was positioned at a grid point. As illustrated in Figure 7, two grooves were machined for each through hole, connecting to two adjacent through holes. The width W of each groove was 1 mm, and the depth D was 0.2 mm.

[0088] Half-cells having a porous metal layer, a mixed layer, and an anode were placed on a processed metal substrate and pressed and fired to create a tight bond between the metal substrate and the half-cells. An anode catalyst was generated by impregnating the porous anode of the metal substrate-attached half-cell with a nitrate solution of Zr, Y, Sc, Ce, Gd, and Ni, and then heat-treating it. An intermediate layer was fabricated on top of the electrolyte layer by PVD. After screen printing on the intermediate layer using a cathode LSC paste, the cell was fired at 1000°C in an N2 atmosphere to complete the full cell. Power generation evaluation was performed using the completed full cell, and the gas diffusion resistance on the low-frequency side, separated by impedance measurement, was 0.2 Ω·cm. 2 Although the values ​​were low, the values ​​were even lower in Example 1. This is likely because Example 1 had a greater number of grooves.

[0089] (Example 3) Through holes with a diameter of Φ3 mm were fabricated on a metal substrate at a pitch of 10 mm (center-to-center distance) using machining. Each through hole was positioned at a grid point. As illustrated in Figure 9, each through hole was machined to be connected to the four nearest through holes, and then to the next four nearest through holes, by eight grooves. The width W of each groove was 0.5 mm, and the depth D was 0.2 mm.

[0090] Half-cells having a porous metal layer, a mixed layer, and an anode were placed on a processed metal substrate and pressed and fired to create a tight bond between the metal substrate and the half-cells. An anode catalyst was generated by impregnating the porous anode of the metal substrate-attached half-cell with a nitrate solution of Zr, Y, Sc, Ce, Gd, and Ni, followed by heat treatment. An intermediate layer was fabricated on the electrolyte layer by PVD. After screen printing on the intermediate layer using a cathode LSC paste, the cell was fired at 1000°C in an N2 atmosphere to complete the full cell. Power generation was evaluated using the completed full cell, and the gas diffusion resistance on the low-frequency side, separated by impedance measurement, was 0.13 Ω·cm. 2 Although both were low, the value was lower in Example 1. This is thought to be because the groove width W was larger in Example 1.

[0091] (Example 4) Through holes with a diameter of Φ3 mm were fabricated on a metal substrate at a pitch of 10 mm (center-to-center distance) using machining. Each through hole was positioned at a grid point. As illustrated in Figure 9, each through hole was machined to be connected to the four nearest through holes, and then to the next four nearest through holes, by eight grooves. The width W of each groove was 1 mm, and the depth D was 0.1 mm.

[0092] Half-cells having a porous metal layer, a mixed layer, and an anode were placed on a processed metal substrate and pressed and fired to create a tight bond between the metal substrate and the half-cell. An anode catalyst was generated by impregnating the porous anode of the metal substrate-attached half-cell with a nitrate solution of Zr, Y, Sc, Ce, Gd, and Ni, followed by heat treatment. An intermediate layer was fabricated on the electrolyte layer by PVD. After screen printing on the intermediate layer using a cathode LSC paste, the cell was fired at 1000°C in an N2 atmosphere to complete the full cell. Power generation was evaluated using the completed full cell, and the gas diffusion resistance on the low-frequency side, separated by impedance measurement, was 0.16 Ω·cm. 2 Although the values ​​were low, the values ​​were even lower in Example 1. This is likely because the grooves were deeper in Example 1.

[0093] (Comparative Example 1) Through holes with a diameter of Φ3 mm were fabricated on a metal substrate at a pitch of 10 mm (center-to-center distance) using machining. No grooves were made in the metal substrate.

[0094] Half-cells having a porous metal layer, a mixed layer, and an anode were placed on a processed metal substrate and pressed and fired to create a tight bond between the metal substrate and the half-cells. An anode catalyst was generated by impregnating the porous anode of the metal substrate-attached half-cell with a nitrate solution of Zr, Y, Sc, Ce, Gd, and Ni, and then heat-treating it. An intermediate layer was fabricated on the electrolyte layer by PVD. After screen printing on the intermediate layer using a cathode LSC paste, the cell was fired at 1000°C in an N2 atmosphere to complete the full cell. Power generation evaluation was performed using the completed full cell, and the gas diffusion resistance on the low-frequency side, separated by impedance measurement, was 1.28 Ω·cm. 2 The resistance increased. This is thought to be because the lack of grooves in the metal substrate suppressed gas diffusion, leading to an increase in diffusion resistance. [Table 1]

[0095] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]

[0096] 5 Metal substrate 10 Porous metal layer 20 mixed layer 21 Metal materials 22. Ceramic Materials 30 anodes 31 Electronically Conductive Ceramics 32 Oxide ion conductive ceramics 33 Oxide ion conductive ceramics 34 Catalyst metals 40 Electrolyte layer 50 Middle Class 51 Through hole 52 Groove 60 Cathode 100 fuel cell

Claims

1. A metal substrate having multiple through holes in the thickness direction, A porous metal layer, mainly composed of metal, is provided on the aforementioned metal substrate. The porous metal layer comprises an anode provided on the porous metal layer, A solid oxide fuel cell, wherein grooves connecting a plurality of through holes are formed on the main surface of the metal substrate on the porous metal layer side.

2. The solid oxide fuel cell according to claim 1, wherein the thickness of the metal substrate is 0.2 mm or more and 1 mm or less.

3. The solid oxide fuel cell according to claim 1 or claim 2, wherein the metal substrate is ferritic stainless steel.

4. The solid oxide fuel cell according to claim 1 or claim 2, wherein the diameter of the through hole is 0.1 mm or more and 6 mm or less.

5. The solid oxide fuel cell according to claim 1 or claim 2, wherein the pitch of the plurality of through holes is 1.2 times or more and 5 times or less the diameter of the through hole.

6. The solid oxide fuel cell according to claim 1 or claim 2, wherein the width of the groove is 1 / 10 or more and 1 / 2 or less of the diameter of the through hole.

7. The solid oxide fuel cell according to claim 1 or claim 2, wherein the depth of the groove is 1 / 10 or more and 1 / 2 or less of the thickness of the metal substrate.

8. The solid oxide fuel cell according to claim 1 or claim 2, wherein the metal substrate has a plurality of through holes arranged at each of the plurality of grid points.

9. The solid oxide fuel cell according to claim 8, wherein the through-hole is connected to the four nearest through-holes by the groove.

10. The solid oxide fuel cell according to claim 8, wherein the through-holes are connected by grooves to four nearest through-holes and four more nearest through-holes after the four aforementioned through-holes.

11. A step of preparing a metal substrate having multiple through holes in the thickness direction and grooves connecting the multiple through holes formed on one main surface, and a half cell having an anode provided on a porous metal layer mainly composed of metal, A method for manufacturing a solid oxide fuel cell, comprising the step of pressurizing and firing the anode side of the half cell against one of the main surfaces of the metal substrate.

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