JP2015065014A - Anode for fuel cell and single fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anode for a fuel cell and a single fuel cell using the anode that can uniformize power generation distribution on a cell surface caused by a fuel gas flow when the anode is used in the single fuel cell.SOLUTION: An anode 10 for a fuel cell has an anode 1, a solid electrolyte layer 2, and a cathode 3, and is used in a single fuel cell 5 where fuel gas is supplied along the surface direction of the anode 1. The anode 10 for the fuel cell consists of a plurality of layers including a blow hole 101 and having at least an outermost layer 11 arranged the farthest from the solid electrolyte layer 2 and an inner layer 12 in contact with the surface of the outermost layer 11 on the side of the solid electrolyte layer 2. An average pore diameter or porosity of the outermost layer 11 is smaller than an average pore diameter or porosity of the inner layer 12.

Description

  The present invention relates to a fuel cell anode and a fuel cell single cell, and more particularly to a fuel cell anode used in a fuel cell single cell using a solid electrolyte as an electrolyte, and a fuel cell single cell using the same.

  Conventionally, a solid electrolyte type fuel cell unit cell having an anode, a solid electrolyte layer, and a cathode is known. In general, in the fuel cell unit cell, the fuel gas supplied from the fuel gas inlet often flows along the surface of the anode and is discharged from the fuel gas outlet.

  Prior Patent Document 1 discloses a fuel cell single cell in which a support having a fuel gas passage for circulating fuel gas therein, an anode layer, a solid electrolyte layer, and a cathode layer are laminated in this order. Has been. This document describes that the porosity in the anode layer portion located downstream in the fuel gas flow direction is larger than the porosity in the anode layer portion located upstream in the fuel gas flow direction. ing.

JP 2012-94427 A

  However, the prior art has problems in the following points. That is, in the fuel cell single cell to which fuel gas is supplied along the surface direction of the anode, a large amount of fuel gas is consumed on the fuel gas inlet side, and the amount of fuel gas reaching the fuel gas outlet side tends to decrease. In some cases, the fuel gas may be exhausted on the fuel gas outlet side. Therefore, there is a problem that the power generation distribution in the cell plane becomes large, and as a result, the temperature distribution in the cell plane becomes large. When the temperature distribution in the cell plane increases, local stress is generated in the cell, which may lead to cell cracking during power generation.

  The present invention has been made in view of the above background, and when used in a single fuel cell, an anode for a fuel cell capable of making the power generation distribution in the cell plane uniform due to the flow of fuel gas. The fuel cell single cell using this was obtained.

One aspect of the present invention is an anode for a fuel cell that has an anode, a solid electrolyte layer, and a cathode, and that is used in a fuel cell single cell that is supplied with fuel gas along the surface direction of the anode. And
The outermost layer disposed farthest from the solid electrolyte layer and a plurality of layers including pores having at least an inner layer in contact with the surface of the outermost layer on the solid electrolyte layer side;
In the anode for a fuel cell, the average pore diameter or porosity of the outermost layer is smaller than the average pore diameter or porosity of the inner layer.

  Another aspect of the present invention includes the anode for a fuel cell, a solid electrolyte layer, and a cathode, and fuel gas is supplied along a surface direction of the anode for the fuel cell. It is in a single fuel cell.

  The fuel cell anode has the above-described configuration. In particular, the average pore diameter or porosity of the outermost layer is configured to be smaller than the average pore diameter or porosity of the inner layer. Therefore, when the fuel cell anode is used in a single fuel cell, it can suppress excessive inflow of the fuel gas into the anode on the upstream side of the gas flow of the supplied fuel gas. The fuel gas can be sufficiently sent to the side. Therefore, the fuel cell anode can achieve uniform power generation distribution in the cell plane due to the flow of fuel gas. As a result, when the fuel cell anode is used in a single fuel cell, the temperature distribution in the cell surface becomes small, local stress is less likely to occur in the cell, and cell cracking during power generation is less likely to occur. . Therefore, the fuel cell anode is effective in improving the reliability of a single fuel cell.

  In addition, the anode for a fuel cell is configured to reduce the amount of fuel gas flowing into the anode by intentionally reducing the average pore diameter or porosity of the outermost layer relative to the inner layer, to the downstream side of the fuel gas flow. Fuel gas can be evenly distributed. Therefore, there are advantages such as good manufacturability as compared with the anode for a fuel cell in which the gas diffusivity is controlled by changing the porosity of the anode in the flow direction of the fuel gas.

  The fuel cell single cell includes the fuel cell anode, a solid electrolyte layer, and a cathode. Therefore, in the fuel cell unit cell, the temperature distribution in the cell surface becomes small, local stress is hardly generated in the cell, and cell cracking during power generation is difficult to occur. Therefore, the fuel cell single cell can exhibit high reliability.

1 is a schematic cross-sectional view of a fuel cell anode and a fuel cell single cell of Example 1. FIG. 2 is an explanatory view schematically showing a structure of a fuel cell anode of Example 1. FIG. 6 is an explanatory view schematically showing the structure of an anode for a fuel cell in Example 2. FIG. FIG. 4 is an explanatory diagram for explaining sheet molding of an outermost layer / diffusion layer forming material containing a pore forming agent in the manufacture of a fuel cell anode of Sample 3. It is explanatory drawing for demonstrating the behavior of the pore making material in the slurry at the time of sheet forming of the outermost layer / diffusion layer forming material. It is explanatory drawing which shows typically the surface which was made into the (a) free surface and (b) the surface which was in contact with the base material at the time of baking outermost layer / diffusion layer forming material. It is explanatory drawing for demonstrating the case where a sheet-like outermost layer / diffusion layer forming material is laminated | stacked and comprised. It is explanatory drawing for demonstrating typically the state of the contact interface by superposition in the case of laminating | stacking and comprising two or more sheet-like outermost layer / diffusion layer forming materials. (A) is before lamination, (b) is immediately after lamination, and (c) is after pressure bonding (heating + compression).

  The anode for a fuel cell is applied to an anode in a solid electrolyte type fuel cell unit cell using a solid electrolyte as an electrolyte. As the solid electrolyte constituting the solid electrolyte layer, a solid oxide ceramic exhibiting oxygen ion conductivity can be used.

  A fuel cell using solid oxide ceramics as a solid electrolyte is called a solid oxide fuel cell (SOFC). The battery structure of the single fuel cell can be a flat plate having a layered anode as a support from the viewpoint of excellent manufacturability and high power generation efficiency.

  Specifically, the fuel cell unit cell is laminated with a solid electrolyte layer, an anode laminated on one surface of the solid electrolyte layer, and an intermediate layer on the other surface of the solid electrolyte layer with or without an intermediate layer. And a cathode as a support. The intermediate layer is mainly a layer for preventing a reaction between the material constituting the cathode and the material constituting the solid electrolyte layer. The cathode and the intermediate layer can be composed of one layer or two or more layers. The fuel gas and oxidant gas supply method is such that the fuel gas supplied to the anode along the surface direction of the anode and the oxidant gas supplied to the cathode along the surface direction of the cathode are orthogonal to each other. A so-called cross flow method or the like supplied to a single fuel cell can be employed.

  In the fuel cell anode, the outermost layer is a layer disposed farthest from the solid electrolyte layer. Fuel gas flows from the outermost layer surface. The outermost layer has a role of adjusting the inflow of the fuel gas to the anode by satisfying the relationship between the average pore diameter or the porosity. On the other hand, the inner layer is disposed closer to the solid electrolyte layer than the outermost layer, and is a layer in contact with the surface of the outermost layer on the solid electrolyte layer side. The fuel gas whose inflow is adjusted flows into the inner layer from the outermost layer. The anode for a fuel cell is not particularly limited with respect to the other layers as long as the above effects can be obtained. The anode for a fuel cell can have a layer configuration of, for example, two layers or three layers. The form of the pores of the plurality of layers such as the outermost layer and the inner layer can be mainly spherical, but is not particularly limited. Moreover, the said pore can contain suitably the pore derived from a pore making material from viewpoints, such as controllability of an average pore diameter and a porosity. However, it is also possible to include pores that are not derived from the pore-forming agent caused by volume reduction accompanying reduction of the catalyst particles.

  Specifically, the anode for a fuel cell is disposed between the outermost layer disposed on the fuel gas supply channel side, the active layer disposed on the solid electrolyte layer side, and the outermost layer and the active layer, A configuration having a solid electrolyte layer side surface in the outermost layer and a diffusion layer as an inner layer in contact with the surface on the side opposite to the solid electrolyte layer side in the active layer can be employed. The active layer is a layer mainly serving as a reaction field for electrochemical reaction on the anode side. The diffusion layer is a layer that can mainly diffuse the supplied fuel gas. In this case, the average pore diameter or porosity of the outermost layer is smaller than the average pore diameter or porosity of the diffusion layer.

  In this case, the fuel gas inflow amount can be controlled in the gas flow direction by the outermost layer, and the fuel gas can flow into the anode relatively uniformly from the gas flow upstream side to the gas flow downstream side. Further, the fuel gas that has flowed in can be appropriately diffused by the diffusion layer. Also, the active layer can cause an electrochemical reaction uniformly in the gas flow direction as compared with the case where the outermost layer is not provided. Therefore, in this case, there is an advantage that the distribution of power generation in the cell plane due to the flow of the fuel gas can be easily uniformed by sufficiently exerting each function by each layer to which the functions are shared.

  The size of the outer shape of other layers including the outermost layer, the inner layer, and the active layer is not particularly limited. The outer dimensions of the outermost layer, inner layer, and other layers can all be the same. In addition, for example, when a diffusion layer and an active layer are provided, the diffusion layer may cover the remaining surface of the active layer other than the surface in contact with the solid electrolyte layer. In this case, the fuel gas can be diffused also from the side surface of the active layer, which is advantageous in improving gas diffusibility.

  In the fuel cell anode, specifically, the average pore diameter of the outermost layer is preferably about 80% to 95%, more preferably about 85% to 90% with respect to the average pore diameter of the inner layer. Can do. In this case, the adjustment of the average pore diameter makes it easy to ensure the inflow restriction of the fuel gas to the outermost layer, and the above-described effects can be easily obtained. In addition, the said average pore diameter is an average value of the pore diameter computed from distribution of the pore diameter measured with a palm porometer etc.-generation frequency. However, when a plurality of peaks appear in the measured pore diameter-occurrence frequency distribution, the average value of the pore diameters for the portion with the highest occurrence frequency is used (the same applies hereinafter).

  In the fuel cell anode, specifically, the average pore diameter of the diffusion layer can be in the range of 0.3 to 5 μm.

  When the average pore diameter of the diffusion layer is 0.3 μm or more, it is easy to quickly diffuse the fuel gas into the active layer by the diffusion layer, which is advantageous for suppressing a decrease in output density. From the viewpoint of ensuring the above effect, the average pore diameter of the diffusion layer is preferably 0.4 μm or more, more preferably 0.6 μm or more, and further preferably 0.8 μm or more. On the other hand, when the average pore diameter of the diffusion layer is 5 μm or less, when the pores are formed by the pore-forming agent, it becomes easy to ensure the continuity of the formed pores, and the diffusion layer can easily diffuse the fuel gas quickly. This is advantageous for suppressing a decrease in output density. From the viewpoint of ensuring the above effect, the average pore size of the diffusion layer is preferably 4 μm or less, more preferably 3 μm or less, and even more preferably 1.5 μm or less.

  In the fuel cell anode, specifically, the average pore size of the active layer may be in the range of 0.1 to 5 μm.

  When the average pore size of the active layer is 0.1 μm or more, the water generated by the electrode reaction is smoothly discharged, so that the power generation output is prevented from dropping instantaneously due to the water remaining without being discharged. It becomes easy. The average pore diameter of the active layer is preferably 0.2 μm or more, more preferably 0.3 μm or more, and further preferably 0.4 μm or more from the viewpoint of ensuring the above effect. On the other hand, when the average pore diameter of the active layer is 5 μm or less, it is easy to secure the number of reaction points, and it is easy to suppress a decrease in output density. From the viewpoint of ensuring the above effect, the average pore diameter of the active layer is preferably 3 μm or less, more preferably 2 μm or less, and even more preferably 1 μm or less.

  In the fuel cell anode, specifically, the porosity of the outermost layer is preferably about 80% to 95%, more preferably about 85% to 90% with respect to the porosity of the inner layer. . In this case, by adjusting the porosity, it becomes easy to ensure the inflow restriction of the fuel gas to the outermost layer, and the above-mentioned effects can be easily obtained. The porosity is a numerical value calculated by {1− (bulk density / apparent density)} × 100 by calculating the apparent density and the bulk density by the Archimedes method.

  In the fuel cell anode, specifically, the porosity of the diffusion layer can be in the range of 30 to 60%.

  When the porosity of the diffusion layer is 30% or more, it is easy to quickly diffuse the fuel gas into the active layer by the diffusion layer, which is advantageous for suppressing a decrease in output density. The porosity of the diffusion layer is preferably 36% or more, more preferably 42% or more, and further preferably 45% or more from the viewpoint of ensuring the above effect. On the other hand, when the porosity of the diffusion layer is 60% or less, when the anode is used as a support, it is easy to ensure the strength as the support, and it is advantageous that it is difficult to break when stacking fuel cell single cells. The porosity of the diffusion layer is preferably 57% or less, more preferably 54% or less, and even more preferably 51% or less, from the viewpoint of ensuring the above effect.

  In the fuel cell anode, specifically, the porosity of the active layer can be in the range of 30 to 50%.

  When the porosity of the active layer is 30% or more, water generated by the electrode reaction is smoothly discharged, so that it is easy to suppress the power generation output from being instantaneously dropped by the water remaining without being discharged. . The porosity of the active layer is preferably 33% or more, more preferably 36% or more, and further preferably 39% or more from the viewpoint of ensuring the above effect. On the other hand, when the porosity of the active layer is 50% or less, it is easy to secure the number of reaction points, and it is easy to suppress a decrease in output density. From the viewpoint of ensuring the above effect, the porosity of the active layer is preferably 48% or less, more preferably 46% or less, and even more preferably 44% or less.

  In the fuel cell anode, each layer can be composed of, for example, a mixture containing a catalyst and a solid electrolyte. Specific examples of the material of the catalyst include nickel (Ni), nickel oxide (NiO, etc.), cobalt (Co), noble metals (Au, Ag, platinum group elements Ru, Rh, Pd, Os, Ir. , Pt, preferably Pt, Pd, Ru) and the like. These can be used alone or in combination of two or more. The catalyst in each layer may be in the form of particles, and all may be the same material or different materials. As the material of the catalyst, nickel and / or nickel oxide can be suitably used. Nickel (nickel oxide becomes nickel in the reducing atmosphere of the anode) has a sufficiently large affinity with hydrogen, which is suitably used for fuel gas, and is less expensive than other metals. Is appropriate.

As the material of the solid electrolyte, specifically, for example, one or more oxides selected from Y ₂ O ₃ , Sc ₂ O ₃ , Yb ₂ O ₃ , and CaO are solid. zirconium oxide-based oxides such as ZrO _2, which is soluble; lanthanum gallate-based _oxide; CeO 2, CeO ₂ to Gd, Sm, Y, La, Nd, Yb, Ca, Dr, and one selected from Ho Alternatively, a cerium oxide-based oxide such as a ceria-based solid solution doped with two or more elements can be exemplified. These can be used alone or in combination of two or more. The solid electrolyte in each layer may be in the form of particles, and may be the same material or different materials. As the material of the solid electrolyte, a zirconia solid electrolyte can be preferably used from the viewpoints of oxygen ion conductivity, mechanical strength, and the like.

  Moreover, the said mixture which can comprise an outermost layer contains a catalyst and solid electrolyte in the range of 30 / 70-70 / 30 by mass ratio, for example, Preferably it is 40 / 60-60 / 40. it can. Moreover, the said mixture which can comprise a diffused layer contains a catalyst and solid electrolyte in the range of 30 / 70-70 / 30 by mass ratio, for example, Preferably it is 40 / 60-60 / 40. it can. The mixture that can constitute the active layer contains the catalyst and the solid electrolyte in a mass ratio of, for example, 30/70 to 70/30, preferably 40/60 to 60/40. it can.

  In the fuel cell anode, the thickness of the outermost layer is preferably 1.5 μm or more, more preferably 2.5 μm or more, from the viewpoint of facilitating uniform distribution of the fuel gas downstream in the gas flow direction. . The thickness of the outermost layer is preferably 15 μm or less, more preferably 10 μm or less, from the viewpoint of making it possible to reduce pressure loss on the upstream side in the gas flow direction as much as possible. In addition, the thickness of the diffusion layer, when used as a support, ensures that it can withstand the mechanical stress applied to a single cell during stacking and that it can withstand the thermal stress applied during power generation. From the viewpoint of facilitating, it is preferably 100 μm or more, more preferably 200 μm or more. The thickness of the diffusion layer is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 500 μm or less, from the viewpoint of facilitating the reduction of fuel gas pressure loss as much as possible. The thickness of the active layer is preferably 10 μm or more, more preferably 15 μm or more from the viewpoint of increasing the diffusion distance of oxygen ions from the solid electrolyte side to the anode in order to ensure an electrochemical reaction field. Can do. On the other hand, the porosity of the active layer is usually intentionally lower than that of the diffusion layer in order to give priority to securing an electrochemical reaction field over gas diffusion. Therefore, it is sufficient that the thickness is sufficient for securing an electrochemical reaction field, and an unnecessarily thick thickness is not desirable from the viewpoint of promptly diffusing gas to the vicinity of the reaction field. Therefore, the thickness of the active layer can be preferably 30 μm or less, more preferably 20 μm or less.

  In the fuel cell single cell, examples of the material constituting each layer include the following, but are not particularly limited.

Examples of the solid electrolyte constituting the solid electrolyte layer include zirconium oxide-based oxides such as yttria-stabilized zirconia (YSZ) and scandia-stabilized zirconia (ScSZ); lanthanum gallate-based oxides; CeO ₂ , CeO ₂ with Gd, Examples include cerium oxide-based oxides such as ceria-based solid solutions doped with one or more elements selected from Sm, Y, La, Nd, Yb, Ca, Dr, and Ho. it can. The solid electrolyte layer has an advantage that the ohmic resistance is reduced by reducing its thickness and the output density is improved, but if the thickness is excessively thin, the probability of occurrence of holes penetrating the solid electrolyte layer increases. The fuel gas or oxidant gas may cross leak through the solid electrolyte layer, resulting in a decrease in power density. From the above viewpoint, the thickness of the solid electrolyte layer is preferably 1 to 20 μm, more preferably 3 to 10 μm.

  Examples of the cathode material include conductive perovskite oxides such as lanthanum-manganese oxides, lanthanum-cobalt oxides, and lanthanum-iron oxides, the perovskite oxides, the solid electrolytes, and the like. The mixture of these can be illustrated. The thickness of the cathode is preferably 10 to 100 μm, more preferably 30 to 50 μm, from the viewpoint of increasing the number of reaction active fields in which oxygen contained in an oxidant gas such as air receives and ionizes electrons on the cathode material surface. It can be.

  Examples of the material for the intermediate layer include the cerium oxide-based oxide. The thickness of the intermediate layer is preferably 1 to 10 μm, more preferably 3 to 7 μm, from the viewpoint of preventing diffusion of the cathode constituent element into the solid electrolyte.

  The fuel cell anode and the fuel cell single cell having the fuel cell anode can be suitably manufactured through the following first to third steps, but are not particularly limited.

  The first step includes an unfired anode forming material that becomes a fuel cell anode by firing, an unfired solid electrolyte layer forming material that becomes a solid electrolyte layer by firing, and an intermediate layer by firing, if necessary. In this step, the unfired intermediate layer forming material is layered in this order and pressed to obtain a laminate. The laminated body can be degreased as necessary.

  Specifically, the anode forming material can include at least an unfired outermost layer forming material that becomes an outermost layer by firing and an unfired inner layer forming material that becomes an inner layer by firing. . In this case, the anode forming material more specifically includes the outermost layer forming material, an unfired diffusion layer forming material that becomes a diffusion layer by firing, and an unfired active layer that becomes an active layer by firing. And a forming material.

  More specifically, each of the above-mentioned forming materials includes catalyst particles, solid electrolyte particles, a pore-forming agent composed of resin particles such as spheres, carbon such as acetylene black, an organic binder, and, if necessary. And can be formed into a sheet containing a plasticizer and the like. In addition, each of the above forming materials has a pore forming agent particle size and addition ratio, catalyst particles and solid electrolyte so that the average pore size or porosity of the outermost layer is smaller than the average pore size or porosity of the inner layer. The particle diameter and content of the particles can be adjusted as appropriate.

  In addition, specifically, the anode forming material can include at least an unfired outermost layer / inner layer forming material that becomes an outermost layer and an inner layer by firing. That is, in this case, the outermost layer is formed on the surface layer portion of the inner layer opposite to the solid electrolyte layer simultaneously with the formation of the inner layer. In this case, more specifically, the anode forming material is an unfired outermost layer / diffusion layer forming material that becomes an outermost layer and a diffusion layer by firing, and an unfired active layer forming material that becomes an active layer by firing. Material.

  More specifically, the outermost layer / inner layer forming material is formed into a sheet shape including catalyst particles, solid electrolyte particles, a pore-forming agent, an organic binder, and a plasticizer as necessary. In addition, the exposed area of the pore former on one surface can be smaller than the exposed area of the pore former on the other surface. However, the outermost layer / inner layer forming material is laminated so that the other surface side is the surface of the solid electrolyte layer forming material side. As a result, the pore-forming agent is burned away by firing, which will be described later, so that the outermost layer is formed on the surface layer portion of the inner layer opposite to the solid electrolyte layer simultaneously with the formation of the inner layer. And it is possible to restrict the inflow of fuel gas into the anode by utilizing the pores of the outermost layer derived from the pore former (the average pore diameter is smaller than the pores of the inner layer derived from the pore former). Become.

  The outermost layer / inner layer forming material is a slurry containing at least catalyst particles, solid electrolyte particles, a pore-forming agent having a spherical shape, and an organic binder. It can be prepared by applying a layer on the substrate and drying it. In this case, in the slurry coated on the substrate, the pores protrude from the free surface of the slurry on the opposite side of the substrate due to the decrease in the slurry weight, the evaporation of the solvent, and the reduction of the slurry surface height accompanying drying. The drug increases. On the other hand, on the surface of the slurry on the substrate side, the pore-forming agent comes into contact with the surface of the substrate in a state close to point contact, and the height from the surface of the substrate is almost naturally aligned. Therefore, in the outermost layer / inner layer forming material, the area of the pore forming agent protruding from the surface on the substrate side is smaller than the area of the pore forming agent protruding from the free surface. In addition, many pore forming agents in the slurry are floating in the slurry. Therefore, according to the above method, it is possible to prepare an outermost layer / inner layer forming material in which the exposed area of the pore former on one surface is smaller than the exposed area of the pore former on the other surface. In addition, the ratio of the average pore diameter of the outermost layer formed after firing and the average pore diameter of the inner layer can be increased as the particle diameter of the pore former is increased.

  In the first step, in obtaining the laminate, the sheet-shaped inner layer forming material (diffusion layer forming material) and the outermost layer / inner layer forming material (outermost layer / diffusion layer forming material) are used as a support. Multiple sheets can be stacked to ensure strength. When a plurality of sheet-shaped outermost layer / inner layer forming materials are stacked, the other surface of the outermost layer / inner layer forming material can be overlapped with the one surface of the outermost layer / inner layer forming material to be overlapped therewith. That's fine. At this time, a gap is generated around the pore-forming agent that protrudes from the free surface at the beginning of the overlapping at the contact interface by the overlapping. However, the binder constituting the outermost layer / diffusion layer forming material is softened and deformed by heating during the subsequent pressure bonding, and the gap is filled. Therefore, the microstructure of the contact interface due to the superposition can be homogenized to such an extent that there is almost no difference from the internal average microstructure (pore forming agent distribution) in the outermost layer / inner layer forming material. Therefore, the above stacking does not adversely affect the pore distribution inside the formed inner layer.

  In the first step, either the outermost layer forming material or the outermost layer / inner layer forming material (outermost layer / diffusion layer forming material) may be used. In the former case, since the outermost layer and the inner layer (diffusion layer) are prepared with different materials, there is an advantage that the average pore diameter and porosity of the outermost layer and inner layer in the obtained fuel cell anode can be easily controlled to the above-described relationship. is there. On the other hand, in the latter case, it is only necessary to prepare the outermost layer / inner layer forming material, which is advantageous in that it can contribute to a reduction in manufacturing cost.

  A 2nd process is a process of baking the said laminated body simultaneously at 1300-1500 degreeC, for example. Thereby, a fired body in which the anode for the fuel cell (in the above example, the outermost layer, the diffusion layer, the active layer), the solid electrolyte layer, and, if necessary, the intermediate layer are laminated in this order is obtained.

  The third step is a step of laminating a cathode forming material that becomes a cathode by firing on the surface of the intermediate layer or the surface of the solid electrolyte layer in the fired body, and firing at 900 to 1200 ° C., for example. is there.

  A paste-like material can be used as the cathode forming material. The cathode forming material can be applied in a layer form on the surface of the intermediate layer or the surface of the solid electrolyte layer by a printing method or the like.

  Thereby, the fuel cell single cell which has the said anode for fuel cells and the said anode for fuel cells can be obtained.

  In addition, each structure mentioned above can be arbitrarily combined as needed, in order to acquire each effect etc. which were mentioned above.

  Hereinafter, an anode for a fuel cell and a single cell for a fuel cell according to examples will be described with reference to the drawings. In addition, about the same member, it demonstrates using the same code | symbol.

Example 1
A fuel cell anode and a fuel cell single cell of Example 1 will be described with reference to FIGS. As shown in FIGS. 1 and 2, the fuel cell anode 10 of this example includes an anode 1, a solid electrolyte layer 2, and a cathode 3, and a fuel gas F along the surface direction of the anode 1. Is used for the single fuel cell 5 to which is supplied.

  The anode 10 for a fuel cell includes a plurality of layers including pores 101 having at least an outermost layer 11 disposed farthest from the solid electrolyte layer 2 and an inner layer 12 in contact with the surface of the outermost layer 11 on the solid electrolyte layer 2 side. It is configured. The average pore diameter of the outermost layer 11 is smaller than the average pore diameter of the inner layer 12.

  Further, as shown in FIG. 1, the fuel cell single cell 5 of the present example includes the fuel cell anode 10, the solid electrolyte layer 2, and the cathode 3 of the present example. Fuel gas F is supplied along the surface direction. Specifically, the fuel cell single cell 5 includes a solid electrolyte layer 2, a fuel cell anode 10 laminated on one surface of the solid electrolyte layer 2, and an intermediate layer 4 on the other surface of the solid electrolyte layer 2. It is a flat single cell having a stacked cathode 3 and a fuel cell anode 10 as a support. Further, the supply system of the fuel gas F and the oxidant gas (not shown) specifically includes the fuel gas F supplied to the anode 1 along the surface direction of the anode 1 and the cathode along the surface direction of the cathode 3. 3 is a so-called cross flow system in which the oxidant gas supplied to the fuel cell 3 is supplied to the single fuel cell 5 so as to be orthogonal to each other. These are described in detail below.

  Specifically, the anode 10 for the fuel cell of the present example includes an outermost layer 11 disposed on the fuel gas F supply channel side, an active layer 13 disposed on the solid electrolyte layer 2 side, an outermost layer 11 and an active layer. A diffusion layer 121 is provided between the outermost layer 11 and the surface of the outermost layer 11 on the side of the solid electrolyte layer 2 and in contact with the surface of the active layer 13 opposite to the side of the solid electrolyte layer 2. In this example, the diffusion layer 121 is the inner layer 12.

  In the fuel cell anode 10 of this example, the average pore diameter of the outermost layer 11 is specifically in the range of 80% to 95% with respect to the average pore diameter of the diffusion layer 121 as the inner layer 12. More specifically, the average pore diameter of the diffusion layer 12 is in the range of 0.3 to 5 μm, and the average pore diameter of the active layer 13 is in the range of 0.1 to 5 μm. Note that the outermost layer 11, the diffusion layer 121 as the inner layer 12, and the pores 101 included in the active layer 13 are mainly derived from the pore-forming agent.

In the fuel cell anode 10 of this example, the outermost layer 11, the diffusion layer 121 as the inner layer 12, and the active layer 13 are each composed of a mixture containing a catalyst and a solid electrolyte. The catalyst is specifically NiO, and the solid electrolyte is specifically yttria-stabilized zirconia (hereinafter, 8YSZ) containing 8 mol% Y ₂ O ₃ as a zirconia-based solid electrolyte. . In this example, the solid electrolyte contained in the outermost layer 11, the diffusion layer 121 as the inner layer 12, and the active layer 13 is such that the particle diameter of the solid electrolyte particles contained in the active layer 13 <the solid electrolyte contained in the outermost layer 11. The relationship of the particle diameter of the particles <the particle diameter of the solid electrolyte particles contained in the diffusion layer 121 as the inner layer 12 is satisfied. The outermost layer 11 has a thickness of 10 μm, the diffusion layer 121 as the inner layer 12 has a thickness of 400 μm, and the active layer 13 has a thickness of 20 μm.

  In this example, the solid electrolyte layer 2 is specifically formed from a zirconia solid electrolyte. More specifically, the zirconia-based solid electrolyte is 8YSZ, which is a zirconium oxide-based oxide, and the thickness thereof is 10 μm.

  In this example, specifically, the intermediate layer 4 is formed of ceria (hereinafter, 10 GDC) doped with 10 mol% of Gd, which is a cerium oxide-based oxide, and has a thickness of 10 μm.

In this example, specifically, the cathode 3 is formed in a layer form from a mixture containing a perovskite oxide and a solid electrolyte. More specifically, the perovskite type oxide is La _1-x Sr _x Co _1-y F _y O ₃ (x = 0.4, y = 0.8, hereinafter, LSCF), and the solid electrolyte is 10GDC, which is a cerium oxide-based oxide. The thickness of the cathode 3 is 40 μm.

  In this example, the fuel cell anode 10, the solid electrolyte layer 2, the intermediate layer 4, and the cathode 3 all have a rectangular shape in plan view. Further, the fuel cell anode 10, the solid electrolyte layer 2, and the intermediate layer 4 have the same outer shape. On the other hand, the outer shape of the cathode 3 is formed smaller than the outer shape of the solid electrolyte layer 2. That is, in this example, the fuel cell single cell 5 is configured such that the outer dimensions of the cathode 3 and the solid electrolyte layer 2 satisfy the relationship of the outer shape of the cathode 3 <the outer shape of the solid electrolyte layer 2.

  The effect of the fuel cell anode of this example will be described.

  The fuel cell anode 10 has the above-described configuration. In particular, the average pore diameter of the outermost layer 11 is configured to be smaller than the average pore diameter of the inner layer 12. Therefore, when the fuel cell anode 10 is used in the single fuel cell 5, it can suppress excessive inflow of the fuel gas F into the anode on the upstream side of the gas flow of the supplied fuel gas F, The fuel gas F can be sufficiently sent to the downstream side of the gas flow. Therefore, the fuel cell anode 10 can achieve a uniform power generation distribution in the cell plane due to the flow of the fuel gas F. As a result, when the fuel cell anode 10 is used for the single fuel cell 5, the temperature distribution in the cell surface becomes small, local stress is hardly generated in the cell, and cell cracking during power generation is difficult to occur. Become. Therefore, the fuel cell anode 10 is effective in improving the reliability of the single fuel cell 5.

  Further, in the fuel cell anode 10 of this example, the inflow amount of the fuel gas F into the anode is reduced by intentionally reducing the average pore diameter of the outermost layer 11 rather than the inner layer 12, so that the gas of the fuel gas F is reduced. The fuel gas can be evenly distributed to the downstream side of the flow. Therefore, there are advantages such as good manufacturability as compared with the anode for a fuel cell in which the gas diffusivity is controlled by changing the porosity of the anode in the flow direction of the fuel gas.

  The anode 10 for the fuel cell of the present example includes an outermost layer 11 disposed on the fuel gas F supply channel side, an active layer 13 disposed on the solid electrolyte layer 2 side, an outermost layer 11 and an active layer 13. And a diffusion layer 121 as an inner layer 12 in contact with the surface on the solid electrolyte layer 2 side of the outermost layer 11 and the surface of the active layer 13 opposite to the solid electrolyte layer 2 side. Therefore, in the fuel cell anode 10 of this example, the outermost layer 11 can control the fuel gas inflow amount in the gas flow direction, and the fuel gas F is relatively uniformly distributed from the gas flow upstream side to the gas flow downstream side. It can flow into the anode. Moreover, the fuel gas F that has flowed in can be appropriately diffused by the diffusion layer 121. In addition, the active layer 13 can cause an electrochemical reaction uniformly in the gas flow direction as compared with the case where the outermost layer 11 is not provided. Therefore, in the anode 10 for the fuel cell of this example, the respective layers 11, 121, 13 to which the functions are shared sufficiently perform the respective functions, thereby making the power generation distribution in the cell plane uniform due to the flow of the fuel gas F. There is an advantage that is easy to plan.

  In the fuel cell anode 10 of this example, the average pore diameter of the diffusion layer 121 is in the range of 0.3 to 5 μm. Therefore, the fuel cell anode 10 of this example is easy to quickly diffuse the fuel gas F into the active layer 13 by the diffusion layer 121, and is advantageous for suppressing a decrease in output density. Further, when the pores 101 are formed by the pore-forming agent, it becomes easy to ensure the continuity of the formed pores 101, and the fuel gas F is easily diffused quickly by the diffusion layer 121, which is advantageous for suppressing the decrease in output density. .

  The effect of the fuel cell single cell of this example is demonstrated.

  The fuel cell single cell 5 includes a fuel cell anode 10, a solid electrolyte layer 2, and a cathode 3. Therefore, in the fuel cell single cell 5, the temperature distribution in the cell surface becomes small, local stress is hardly generated in the cell, and cell cracking during power generation is difficult to occur. Therefore, the fuel cell single cell 5 can exhibit high reliability.

(Example 2)
A fuel cell anode and a fuel cell single cell of Example 2 will be described with reference to FIG. As shown in FIG. 3, in the fuel cell anode 10 of this example, the porosity of the outermost layer 11 is smaller than the porosity of the inner layer 12. Moreover, the fuel cell single cell 5 of this example uses the fuel cell anode 10 of Example 2.

  In the fuel cell anode 10 of this example, the porosity of the outermost layer 11 is specifically in the range of 80 to 95% with respect to the porosity of the diffusion layer 121 as the inner layer 12. More specifically, the porosity of the diffusion layer 121 is in the range of 30 to 60%, and more specifically, the porosity of the active layer 13 is in the range of 30 to 50%. Other configurations are the same as those of the anode 10 for a fuel cell and the single fuel cell 5 of Example 1 except for the configuration of the average porosity.

  The fuel cell anode 10 of this example has the above-described configuration. In particular, the porosity of the outermost layer 11 is configured to be smaller than the porosity of the inner layer 12. In the fuel cell anode 10 of this example, the inflow amount of the fuel gas F into the anode is reduced by intentionally reducing the porosity of the outermost layer 11 rather than the inner layer 12, and the gas flow downstream side of the fuel gas F Fuel gas can be evenly distributed. Therefore, the same effect as the fuel cell anode 10 of Example 1 can be obtained. The fuel cell single cell 5 of this example uses the fuel cell anode 10 of this example. Therefore, the fuel cell single cell 5 of the present example can achieve the same effects as the fuel cell single cell 5 of Example 1.

Hereinafter, it demonstrates more concretely using an experiment example.
<Experimental example 1>
(Material preparation)
NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.3 μm), spherical resin particles (average particle size: 1 μm) as a pore-forming agent, polyvinyl butyral (organic material), A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 65:35. Content of a pore making material is 7 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped outermost layer forming material. The average particle diameter is the particle diameter (diameter) d50 when the volume-based cumulative frequency distribution measured by the laser diffraction / scattering method shows 50% (hereinafter the same).

  NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.5 μm), spherical resin particles (average particle size: 1.5 μm) as a pore-forming agent, and polyvinyl butyral (organic material) A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 65:35. Content of a pore making material is 7 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped diffusion layer forming material.

  NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.3 μm), spherical resin particles (average particle size: 0.8 μm) as a pore-forming agent, and polyvinyl butyral (organic material) A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 60:40. Content of a pore making material is 3 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-form active layer forming material.

  A slurry was prepared by mixing 8YSZ powder (average particle diameter: 0.3 μm), polyvinyl butyral (organic material), isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped solid electrolyte layer forming material.

  A slurry was prepared by mixing 10 GDC powder (average particle size: 0.2 μm), polyvinyl butyral (organic material), isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped intermediate layer forming material.

LSCF (La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ ) powder (average particle size: 0.45 μm), 10 GDC powder (average particle size: 0.2 μm), ethyl cellulose (organic material) ) And terpineol (solvent) were mixed in a ball mill to prepare a paste-like cathode forming material. The mass ratio of the LSCF powder to the 10GDC powder is 90:10.

(First step)
The sheet-shaped outermost layer forming material, the sheet-shaped diffusion layer forming material, the sheet-shaped active layer forming material, the sheet-shaped solid electrolyte layer forming material, and the sheet-shaped intermediate layer forming material in this order. It laminated | stacked and crimped | bonded and the laminated body was obtained. At this time, the sheet-like material for forming a diffusion layer was formed by superposing five sheets. Note that the CIP molding method was used for pressure bonding. The CIP molding conditions were a temperature of 80 ° C., a pressing force of 50 MPa, and a pressing time of 10 minutes. Moreover, the laminated body was degreased after the pressure bonding.

(Second step)
Next, the laminate was fired at 1350 ° C. for 2 hours. Thus, a sintered body in which the outermost layer, the diffusion layer, the active layer, the solid electrolyte layer, and the intermediate layer were laminated in this order was obtained.

(Third step)
Next, a cathode forming material was applied to the surface of the intermediate layer in the sintered body by a screen printing method, and baked (baked) at 900 ° C. for 2 hours to form a layered cathode. The cathode forming material is not printed up to the outer edge of the intermediate layer, and the outer shape of the cathode layer is smaller than the outer shape of the solid electrolyte layer. As a result, a fuel cell single cell having a fuel cell anode as a support was obtained. The obtained fuel cell anode and fuel cell single cell are designated as Sample 1 fuel cell anode and fuel cell single cell. The thickness of the outermost layer is 5 μm, and the average pore diameter of the outermost layer is 0.8 μm. The thickness of the diffusion layer is 400 μm, and the average pore diameter of the diffusion layer is 1 μm. The thickness of the active layer is 20 μm, and the average pore size of the active layer is 0.5 μm. The solid electrolyte layer has a thickness of 10 μm, the intermediate layer has a thickness of 10 μm, and the cathode has a thickness of 40 μm.

<Experimental example 2>
NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.3 μm), spherical resin particles (average particle size: 1 μm) as a pore-forming agent, polyvinyl butyral (organic material), A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 65:35. Content of a pore making material is 5 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped outermost layer forming material.

  NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.5 μm), spherical resin particles (average particle size: 1.5 μm) as a pore-forming agent, and polyvinyl butyral (organic material) A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 65:35. Content of a pore making material is 7 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped diffusion layer forming material.

  NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.3 μm), spherical resin particles (average particle size: 0.8 μm) as a pore-forming agent, and polyvinyl butyral (organic material) A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 60:40. Content of a pore making material is 3 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-form active layer forming material.

  Then, a fuel cell single cell having a fuel cell anode as a support was prepared in the same manner as in Experimental Example 1 except that the prepared outermost layer forming material, diffusion layer forming material, and active layer forming material were used. Obtained. The obtained fuel cell anode and fuel cell single cell are designated as Sample 2 fuel cell anode and fuel cell single cell. The outermost layer has a porosity of 45%, the diffusion layer has a porosity of 48%, and the active layer has a porosity of 42%. Other configurations are the same as those in Experimental Example 1.

<Experimental example 3>
(Material preparation)
NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.3 μm), spherical resin particles (average particle size: 1.5 μm) as a pore-forming agent, and polyvinyl butyral (organic material) A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 65:35. Content of a pore making material is 7 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-shaped outermost layer / diffusion layer forming material.

  As shown in FIG. 4, the outermost layer / diffusion layer forming material 60 has a configuration in which the exposed area of the pore former 61 on one surface is smaller than the exposed area of the pore former 61 on the other surface. As shown in FIG. 5, the catalyst particles (not shown), the solid electrolyte particles (not shown), the pore former 61 composed of spherical resin particles, and the organic binder (not shown) are at least When the slurry 62 containing the slurry is applied in a layered manner on the substrate 65 using the doctor blade method and dried, the pore-forming agent 61 in the slurry 62 is formed with the following behavior. is there. That is, as shown in FIG. 5, when the slurry 62 containing the pore former 61 is formed into a sheet, the pore former 61 can flow in the slurry 62. In particular, when the pore-forming agent 61 has a spherical shape close to a spherical shape, it easily flows in the slurry 62. Here, in the slurry 62 coated on the substrate 65, the pore former 61 present on the surface layer side of the slurry 62 is initially aligned at the tip of the edge 66 of the doctor blade. As the time elapses, the pore-forming agent 61 that protrudes from the free surface 63 of the slurry 62 increases due to the weight of the slurry 62, the evaporation of the solvent (leveling), and the decrease in the surface height of the slurry 62 that accompanies drying. . On the other hand, on the surface of the slurry 62 on the base material 65 side, the pore former 61 comes into contact with the surface of the base material 65 in a state close to point contact, and the height from the surface of the base material 65 is almost naturally aligned. Therefore, as shown in FIG. 4, in the outermost layer / diffusion layer forming material 60, the area of the pore former 61 that protrudes from the base-side surface 64 is the area of the pore former 61 that protrudes from the free surface 63. Smaller than that. When the outermost layer / diffusion layer forming material 60 was fired at 1350 ° C. for 2 hours, as shown in FIG. 6, the pore diameter of the pores 101 on the surface 601 in contact with the base material 65 (FIG. 6B). Is smaller than the pore diameter (see FIG. 6A) of the pores 101 on the surface 602 that is the free surface 63. From this, the pore forming agent 61 is burned out by firing the outermost layer / diffusion layer forming material 60, and the outermost layer is formed on the surface layer portion of the diffusion layer 121 opposite to the solid electrolyte layer 2 simultaneously with the formation of the diffusion layer 121. 11 can be said to be formed.

  NiO powder (average particle size: 1 μm), 8YSZ powder (average particle size: 0.3 μm), spherical resin particles (average particle size: 0.8 μm) as a pore-forming agent, and polyvinyl butyral (organic material) A slurry was prepared by mixing isoamyl acetate, 2-butanol and ethanol (mixed solvent) with a ball mill. The mass ratio of NiO powder and 8YSZ powder is 60:40. Content of a pore making material is 3 mass parts with respect to a total of 100 mass parts of NiO-8YSZ. The slurry was applied in a layer form on a plastic substrate using a doctor blade method and dried to prepare a sheet-form active layer forming material.

  The same sheet-like solid electrolyte layer forming material, sheet-like intermediate layer forming material, and paste-like cathode forming material as in Experimental Example 1 were prepared.

(First step)
A sheet-shaped outermost layer / diffusion layer forming material, a sheet-shaped active layer forming material, a sheet-shaped solid electrolyte layer forming material, and a sheet-shaped intermediate layer forming material are laminated in this order, and then pressed. A laminate was obtained. Note that the CIP molding method was used for pressure bonding. The CIP molding conditions were a temperature of 80 ° C., a pressing force of 50 MPa, and a pressing time of 10 minutes. Moreover, the laminated body was degreased after the pressure bonding.

  At this time, the sheet-like material for forming a diffusion layer was formed by superposing five sheets. However, the superposition was performed so that the free surface 63 and the base-side surface 64 of the outermost layer / diffusion layer forming material 60 were in contact with each other, as shown in FIG. As shown in FIG. 8, a gap 603 is generated around the pore-forming agent 61 that protrudes from the free surface 63 at the beginning of the superposition at the contact interface by superposition (see FIG. 8B). However, the binder constituting the outermost layer / diffusion layer forming material 60 is softened and deformed by heating at the time of subsequent pressure bonding, and the gap 603 is filled. Therefore, the microstructure of the contact interface due to the superposition is homogenized to an extent that there is almost no difference from the average microstructure (pore forming agent distribution) inside the outermost layer / diffusion layer forming material 60.

(Second step)
Next, the laminate was fired at 1350 ° C. for 2 hours. Thus, a sintered body in which the outermost layer, the diffusion layer, the active layer, the solid electrolyte layer, and the intermediate layer were laminated in this order was obtained.

(Third step)
Next, a cathode forming material was applied to the surface of the intermediate layer in the sintered body by a screen printing method, and baked (baked) at 900 ° C. for 2 hours to form a layered cathode. The cathode forming material is not printed up to the outer edge of the intermediate layer, and the outer shape of the cathode layer is smaller than the outer shape of the solid electrolyte layer. As a result, a fuel cell single cell having a fuel cell anode as a support was obtained. The obtained fuel cell anode and fuel cell single cell are referred to as Sample 3 fuel cell anode and fuel cell single cell. The thickness of the outermost layer is 3 μm, and the average pore diameter of the outermost layer is 0.5 μm. The thickness of the diffusion layer is 400 μm, and the average pore diameter of the diffusion layer is 1 μm. The thickness of the active layer is 20 μm, and the average pore size of the active layer is 0.5 μm. The solid electrolyte layer has a thickness of 10 μm, the intermediate layer has a thickness of 10 μm, and the cathode has a thickness of 40 μm.

  As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the said Example, A various change is possible within the range which does not impair the meaning of this invention.

DESCRIPTION OF SYMBOLS 1 Anode 2 Solid electrolyte layer 3 Cathode 5 Fuel cell single cell 10 Anode for fuel cells 101 Pore 11 Outermost layer 12 Inner layer F Fuel gas

Claims (7)

A fuel cell single cell having an anode (1), a solid electrolyte layer (2), and a cathode (3), to which fuel gas (F) is supplied along the surface direction of the anode (1) ( A fuel cell anode (10) used in 5),
A pore having at least an outermost layer (11) arranged farthest from the solid electrolyte layer (2) and an inner layer (12) in contact with the surface on the solid electrolyte layer (2) side of the outermost layer (11) ( 101) including a plurality of layers,
The anode (10) for a fuel cell, wherein the outermost layer (11) has an average pore diameter or porosity smaller than the average pore diameter or porosity of the inner layer (12).   The outermost layer (11) disposed on the fuel gas (F) supply flow path side, the active layer (13) disposed on the solid electrolyte layer (2) side, the outermost layer (11), and the activity Between the surface of the outermost layer (11) on the side of the solid electrolyte layer (2) and the surface of the active layer (13) opposite to the side of the solid electrolyte layer (2). The anode (10) for a fuel cell according to claim 1, further comprising a diffusion layer (121) as the inner layer (12) in contact therewith.   The anode (10) for a fuel cell according to claim 2, wherein the average pore diameter of the diffusion layer (121) is in the range of 0.3 to 5 µm.   The anode (10) for a fuel cell according to claim 2 or 3, wherein the average pore diameter of the active layer (13) is 0.1 to 5 µm.   The anode (10) for a fuel cell according to claim 2, wherein the porosity of the diffusion layer (121) is in the range of 30 to 60%.   The anode (10) for a fuel cell according to claim 2 or 5, wherein the porosity of the active layer (13) is in the range of 30 to 50%.   A fuel cell anode (10) according to any one of claims 1 to 6, a solid electrolyte layer (2), and a cathode (3), wherein the fuel cell anode (10) A fuel cell (5), wherein fuel gas (F) is supplied along the surface direction.

Images