JPWO2019106879A1 - Method for manufacturing metal porous body, fuel cell and metal porous body - Google Patents

Abstract

The present disclosure is a metal porous body having a porous body base material and a heat-resistant coating film, and the porous body base material has a skeleton having a nickel alloy on the surface and continuous pores formed by the skeleton. The heat-resistant coating film covers the surface of the skeleton, and the metal porous body provides a metal porous body having a flat plate-like appearance.

Description

The present disclosure relates to a metal porous body, a fuel cell, and a method for producing the metal porous body. This application claims priority based on Japanese Patent Application No. 2017-228595, which was filed on November 29, 2017. All the contents of the Japanese patent application are incorporated herein by reference.

Among various fuel cells, the solid oxide fuel cell (SOFC, hereinafter also referred to as “SOFC”) is a solid oxide fuel cell (PEFC) or a phosphoric acid type fuel cell. It needs to be operated at a higher temperature than a fuel cell (Phosphoric Acid Fuel Cell; PAFC). However, SOFCs are being actively developed because they have advantages such as high power generation efficiency, no need for expensive catalysts such as platinum, and utilization of waste heat.
The SOFC includes a solid electrolyte layer formed of a solid oxide and an electrode layer laminated on both sides of the solid electrolyte layer. In addition, a porous current collector is provided to collect and extract the electrons generated by the electrodes. This current collector often has a function as a gas diffusion layer in order to diffuse the gas supplied to the electrodes to generate electricity efficiently.

A carbon structure or a stainless steel (SUS) structure is generally used for the gas diffusion layer of the fuel cell. A groove serving as a gas flow path is formed in the carbon structure and the SUS structure. The width of the groove is about 500 μm, and it is a continuous linear shape. Since the grooves are provided in about 1/2 of the area of the surface where the carbon structure and the SUS structure come into contact with the electrolyte, the porosity of the gas diffusion layer is about 50%.
Since the gas diffusion layer as described above does not have a very high porosity and has a large pressure loss, there is a problem in increasing the output while reducing the size of the fuel cell.

As a method for producing a metal porous body having a high porosity and a large surface area, a method of forming a metal layer on the surface of a resin molded body such as a foamed resin is known. For example, in Japanese Patent Application Laid-Open No. 11-154517 (Patent Document 1), the surface of the skeleton of a resin molded product is subjected to a conductive treatment, an electroplating layer made of metal is formed on the surface, and the resin molded product is provided as necessary. A method for producing a metal porous body by incineration and removal is described.

Japanese Unexamined Patent Publication No. 11-154517

The metal porous body according to one aspect of the present disclosure is
A flat metal porous body having continuous pores,
The skeleton of the metal porous body has a heat-resistant coating film formed on the surface of a nickel alloy.
It is a metal porous body.
The method for producing a metal porous body according to one aspect of the present disclosure is as follows.
A method for producing a metal porous body according to one aspect of the present disclosure described above.
A preparation process for preparing a flat plate-shaped porous base material having continuous pores, and
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous base material, and
Have,
At least the surface of the skeleton of the porous substrate is formed of a nickel alloy.
A method for producing a porous metal body.

In other words, the metal porous body according to another aspect of the present disclosure is
A metal porous body having a porous body base material and a heat-resistant coating film.
The porous base material is
A skeleton with a nickel alloy on the surface and
It has continuous pores formed by the skeleton and
The heat-resistant coating film covers the surface of the upper skeleton and
The metal porous body has a flat plate-like appearance.
It is a metal porous body.
In addition, the method for producing a metal porous body according to another aspect of the present disclosure is described.
The above method for producing a metal porous body.
A preparation step of preparing a porous base material having the skeleton and the continuous pores formed by the skeleton, and
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous substrate,
Have,
The porous base material has a flat plate-like appearance, and has a flat plate shape.
The skeleton of the porous substrate has a nickel alloy on its surface.
This is a method for producing a metal porous body.

FIG. 1 is an enlarged photograph showing the structure of a skeleton of an example of a metal porous body having a skeleton having a three-dimensional network structure. FIG. 2 is an enlarged view showing an outline of a partial cross section of an example of a metal porous body according to the embodiment of the present disclosure. FIG. 3 is a schematic view showing an example of a state in which areas A to E are defined on the metal porous body in a method of measuring the average film thickness of the heat-resistant coating film in the metal porous body. FIG. 4 is a diagram showing an outline of an image when a cross section of the skeleton (cross section taken along the line AA of FIG. 2) in the area A of the metal porous body shown in FIG. FIG. 5 is a schematic view showing an example of the field of view (i) when the heat-resistant coating film 11 shown in FIG. 4 is magnified and observed with a scanning electron microscope. FIG. 6 is a schematic view showing an example of a field of view (ii) when the heat-resistant coating film 11 shown in FIG. 4 is magnified and observed with a scanning electron microscope. FIG. 7 is a schematic view showing an example of a field of view (iii) when the heat-resistant coating film 11 shown in FIG. 4 is magnified and observed with a scanning electron microscope. FIG. 8 is a diagram showing an outline of a partial cross section of an example of a porous base material having a skeleton having a three-dimensional network structure. FIG. 9 is a diagram showing an outline of a partial cross section of another example of a porous base material having a skeleton having a three-dimensional network structure. FIG. 10 is a photograph of a urethane foam resin as an example of a resin molded body having a skeleton having a three-dimensional network structure.

[Issues to be solved by this disclosure]
The present inventors have studied the use of a metal porous body having a high porosity instead of the carbon structure and the SUS structure as the current collector and gas diffusion layer of the fuel cell.
SOFC is a fuel cell that operates at a high temperature of about 800 ° C. In SOFC, hydrogen and carbon monoxide are supplied to the negative electrode (fuel electrode), and air (oxygen) is supplied to the positive electrode (air electrode). Therefore, when a metal porous body is used as the gas diffusion layer of the air electrode of the SOFC, the metal porous body has stability for a long period of time even under extremely severe conditions such as a high temperature of about 800 ° C. and an oxidizing atmosphere. You need to use your body.
Therefore, the present inventors have made extensive efforts to produce a metal porous body that can be used even under high-temperature oxidation conditions of about 800 ° C. First, focusing on nickel tungsten (NiW) and nickel molybdenum (NiMo) as alloys having excellent oxidation resistance, a metal porous body having a skeleton made of nickel tungsten or nickel molybdenum was prepared. Then, the heat treatment was performed in the air at 800 ° C. for 500 hours.
As a result, even if the skeleton is a metal porous body made of nickel tungsten or nickel molybdenum, cracks or cracks may occur in a part of the skeleton after long-term heat treatment in a high-temperature oxidizing atmosphere of about 800 ° C. Found.

Therefore, in view of the above problems, the present disclosure has long-term stability even under high-temperature oxidation conditions, and is a metal porous body that can be suitably used as a current collector and a gas diffusion layer for an air electrode of SOFC. The purpose is to provide the body.

[Effect of this disclosure]
According to the present disclosure, there is provided a metal porous body which has stability for a long period of time even under high temperature oxidation conditions and can be suitably used as a current collector and a gas diffusion layer for SOFC air electrodes. be able to.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.
(1) The metal porous body according to one aspect of the present disclosure is
A metal porous body having a porous body base material and a heat-resistant coating film.
The porous base material is
A skeleton with a nickel alloy on the surface and
It has continuous pores formed by the skeleton and
The heat-resistant coating film covers the surface of the upper skeleton and
The metal porous body has a flat plate-like appearance.
It is a metal porous body.
According to the aspect of the disclosure described in (1) above, it has stability for a long period of time even under high temperature oxidation conditions, and can be suitably used as a current collector and gas diffusion layer for an air electrode of SOFC. A possible metal porous body can be provided.

(2) The metal porous body described in (1) above is
The heat-resistant coating film preferably contains silver or cobalt.
According to the disclosed aspect described in (2) above, it is possible to provide a metal porous body having excellent conductivity even under high temperature oxidation conditions.

(3) The metal porous body according to the above (1) or (2) is
The heat-resistant coating film preferably has an average film thickness of 1 μm or more.
According to the disclosed aspect described in (3) above, it is possible to provide a metal porous body having better high temperature oxidation resistance.

(4) The metal porous body according to any one of the above (1) to (3) is
It is preferable that the nickel alloy contains an alloy of nickel and any one or more metals selected from the group consisting of tungsten, molybdenum, aluminum and titanium as a main component.
According to the disclosed aspect described in (4) above, it is possible to provide a metal porous body having high corrosion resistance and high strength.
The main component is the component having the largest proportion in the nickel alloy.

(5) The metal porous body according to any one of the above (1) to (4) is
The shape of the skeleton is preferably a three-dimensional network structure.
(6) The metal porous body according to any one of the above (1) to (5) is
The porosity is preferably 60% or more and 98% or less.
(7) The metal porous body according to any one of the above (1) to (6) is
The average pore diameter is preferably 50 μm or more and 5000 μm or less.
According to the disclosed aspect according to any one of the above (5) to (7), it is possible to provide a lightweight metal porous body having a large surface area.

(8) The metal porous body according to any one of the above (1) to (7) is
The thickness is preferably 500 μm or more and 5000 μm or less.
According to the disclosed aspect described in (8) above, it is possible to provide a lightweight and high-strength metal porous body.
The thickness of the above-mentioned metal porous body means the distance between the main surfaces of the flat metal porous body.

(9) The fuel cell according to one aspect of the present disclosure is
A fuel cell comprising the metal porous body according to any one of (1) to (8) above as a gas diffusion layer.
According to the aspect of the disclosure described in (9) above, it is possible to provide a small and lightweight fuel cell having high power generation efficiency.

(10) The method for producing a porous metal body according to one aspect of the present disclosure is as follows.
The method for producing a porous metal body according to any one of (1) to (8) above.
A preparation step of preparing a porous base material having the skeleton and the continuous pores formed by the skeleton, and
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous substrate,
Have,
The porous base material has a flat plate-like appearance, and has a flat plate shape.
The skeleton of the porous substrate has a nickel alloy on its surface.
A method for producing a porous metal body.
(11) The method for producing a metal porous body according to (10) above is
The preparation step is performed by plating a nickel alloy on the surface of the skeleton and the resin molded body having continuous pores formed by the skeleton.
The resin molded product preferably has a flat plate-like appearance.
According to the aspect of the disclosure described in the above (10) or the above (11), it is possible to provide a method for producing a metal porous body capable of producing the metal porous body according to the above (1).

(12) The method for producing a metal porous body according to the above (10) or (11) is described.
The shape of the skeleton of the porous base material is preferably a three-dimensional network structure.
According to the aspect of the disclosure described in the above (12), it is possible to provide a method for producing a metal porous body capable of producing the metal porous body according to the above (5).

[Details of Embodiments of the present disclosure]
Specific examples of the metal porous body, the fuel cell, and the method for producing the metal porous body according to the embodiment of the present disclosure will be described in more detail below. It should be noted that the present invention is not limited to these examples, and is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

<Metal porous body>
The metal porous body according to the embodiment of the present disclosure has continuous pores and has a flat plate shape as a whole. In one aspect of the present embodiment, the metal porous body has a porous body base material and a heat-resistant coating film. The porous substrate has a skeleton and continuous pores formed by the skeleton. Further, the metal porous body has a flat plate-like appearance. In the metal porous body, the continuous pores may be formed so as to penetrate at least the opposing main surfaces. In other words, the continuous pores may be formed so as to penetrate the opposing main surfaces of the metal porous body in the above shape. From the viewpoint of increasing the surface area of the metal porous body, it is preferable that as many continuous pores as possible are formed. Examples of the shape of the skeleton of the porous metal body (the shape of the skeleton of the porous metal base material) include a mesh-like shape such as punching metal and expanded metal, and a shape such as a three-dimensional network structure. Here, the "three-dimensional network structure" means a structure in which the constituent solid components (for example, metal, resin, etc.) are three-dimensionally spread in a network shape. It is not necessary that the skeleton of the porous metal body itself (or the skeleton of the porous body base material described later) has continuous pores. In other words, the skeleton itself does not have to be porous.

The skeleton of the metal porous body has a heat-resistant coating film formed on the surface of the nickel alloy. That is, a nickel alloy is used as a base material, and a heat-resistant coating film is formed so as to cover the entire surface thereof. In one aspect of the present embodiment, it can be understood that the porous substrate has a skeleton having a nickel alloy on the surface and a heat-resistant coating film covering the surface of the skeleton. When the heat-resistant coating film is not formed on the surface of the skeleton of the porous metal body (the surface of the skeleton of the porous metal substrate) and the skeleton is formed by nickel tungsten or nickel molybdenum, the metal porous body is 800. When exposed to an oxidizing atmosphere at a high temperature of about ° C. for a long time, a part of the skeleton may be cracked or cracked, which may make it unsuitable for use depending on the application of the metal porous body. On the other hand, in the metal porous body according to the embodiment of the present disclosure, a heat-resistant coating film is formed on the surface of a nickel alloy (skeleton of the porous body base material). Therefore, even if the metal porous body is exposed to an oxidizing atmosphere at a high temperature of about 800 ° C., the skeleton can be used stably for a long time without cracking or cracking. Therefore, the metal porous body according to the embodiment of the present disclosure can be preferably used without lowering the strength of the skeleton even if it is used as a gas diffusion layer of the air electrode of SOFC, for example. Further, since the metal porous body has a large surface area, more fuel gas can be diffused. Therefore, the metal porous body can increase the contact opportunity between the fuel gas and the electrolyte to provide SOFC having high power generation efficiency.

The heat-resistant coating film may be a metal or alloy that is stable in a high-temperature oxidizing atmosphere, such as silver (Ag), cobalt (Co), gold (Au), and platinum (Pt). From the viewpoint of suppressing the production cost of the metal porous body, the heat-resistant coating film is preferably silver or cobalt. In one aspect of the present embodiment, the heat-resistant coating film contains, for example, a metal or alloy that is stable in a high-temperature oxidizing atmosphere, such as silver (Ag), cobalt (Co), gold (Au), and platinum (Pt). It may contain silver or cobalt.
Since silver and gold have very high conductivity, the conductivity of the metal porous body can be increased. In addition, the surface of cobalt becomes cobalt oxide due to the influence of oxygen. Cobalt oxide becomes conductive in a high temperature environment of about 800 ° C. Therefore, when the heat-resistant coating film is silver, gold, or cobalt, the metal porous body according to the embodiment of the present disclosure has a good function not only as a gas diffusion layer but also as a current collector in the fuel cell.

The heat-resistant coating film preferably has an average film thickness of 1 μm or more. When the average film thickness of the heat-resistant coating film is 1 μm or more, the metal porous body can be kept stable for a long period of time even in an oxidizing atmosphere at a high temperature of about 800 ° C. Heat resistant coatings are generally expensive. Therefore, from the viewpoint of suppressing the production cost of the metal porous body, the average film thickness of the heat-resistant coating film is preferably about 50 μm or less. From these viewpoints, the average film thickness of the heat-resistant coating film is more preferably 3 μm or more and 30 μm or less, and further preferably 5 μm or more and 20 μm or less.

The nickel alloy may contain an alloy of nickel and a metal other than nickel as a main component, and may intentionally or inevitably contain a component other than the alloy of nickel and a metal other than nickel. The main component means the component having the largest proportion in the nickel alloy. For example, the main component may be a component that accounts for 50% or more of the nickel alloy.
The nickel alloy is preferably one or more metals selected from the group consisting of nickel and tungsten, molybdenum, aluminum and titanium from the viewpoint that it is preferable that the nickel alloy has relatively excellent oxidation resistance and high strength. It is preferable to use the alloy with and as the main component. That is, it is preferable that the nickel alloy contains nickel tungsten (NiW), nickel molybdenum (NiMo), nickel aluminum (NiAl) or nickel titanium (NiTi) as main components.

As described above, the shape of the skeleton of the metal porous body (the shape of the skeleton of the porous body base material) may be a mesh shape, but a three-dimensional network structure is more preferable. When the shape of the skeleton is a three-dimensional network structure, the surface area can be further increased as compared with the skeleton having a shape such as punching metal or expanded metal. Further, since the shape of the skeleton is more complicated, more gas can be diffused when used as a gas diffusion layer of a fuel cell.

In the following, the metal porous body according to the embodiment of the present disclosure will be described in more detail by taking the case where the skeleton of the metal porous body has a three-dimensional network structure as an example.
FIG. 1 shows an enlarged photograph showing a skeleton of a three-dimensional network structure of an example of a metal porous body according to the embodiment of the present disclosure. Further, FIG. 2 shows an enlarged schematic view of the cross section of the metal porous body shown in FIG. 1 in an enlarged view. Note that FIG. 1 is an example of a metal porous body in which a silver plating film is formed on the surface of the skeleton (the surface of the skeleton of the porous body base material) as a heat-resistant coating film.
When the shape of the skeleton has a three-dimensional network structure, the inside 14 of the skeleton 13 of the metal porous body 10 is typically hollow as shown in FIG. The surface of the skeleton 13 has a structure in which the heat-resistant coating film 11 is formed so as to cover the surface of the nickel alloy 12 which is the base material (porous base material). Further, the metal porous body 10 has continuous pores, and the pore portion 15 is formed by the skeleton 13.

Although the thickness of the heat-resistant coating film 11 is shown in FIG. 2 to be about the same as the thickness of the nickel alloy 12, the average film thickness of the heat-resistant coating film 11 is preferably 1 μm or more and 50 μm or less as described above. Further, the thickness of the heat-resistant coating film 11 is usually thinner than that of the nickel alloy 12. The average film thickness of the heat-resistant coating film 11 is measured by observing the cross section of the skeleton 13 of the metal porous body 10 with an electron microscope as follows. The outline of the method of measuring the average film thickness of the heat-resistant coating film 11 is shown in FIGS. 3 to 7.

First, for example, as shown in FIG. 3, the metal porous body 10 having a flat plate appearance is arbitrarily divided into areas, and five measurement points (areas A to E) are selected. Then, one skeleton 13 of the metal porous body 10 is arbitrarily selected in each area, and the cross section of the skeleton shown in FIG. 2 is observed with a scanning electron microscope (SEM). As shown in FIG. 4, the cross section of the skeleton 13 of the metal porous body 10 along the line AA has a substantially triangular shape. On the other side, the A-A line cross section of the skeleton of the metal porous body may be circular or square. In the example shown in FIG. 4, the inside 14 of the skeleton of the metal porous body 10 is hollow, and a film of nickel alloy 12 is provided facing the hollow portion. The heat-resistant coating film 11 is formed so as to cover the outer surface of the nickel alloy 12.

If the entire A-A line cross section of the skeleton can be observed by SEM, the magnification is further increased so that the entire thickness direction of the heat-resistant coating film 11 can be confirmed, and the thickness direction can be seen as large as possible within one field of view. Set to. Then, the maximum thickness and the minimum thickness of the heat-resistant coating film 11 are measured in three fields of view with respect to the AA line cross section of the same skeleton by changing the field of view. In all areas, the maximum and minimum thicknesses of the heat-resistant coating film 11 were measured from three viewpoints for the A-A line cross section of an arbitrary skeleton at one location, and the average of them was the average film thickness of the heat-resistant coating film 11. That is.

As an example, FIG. 5 shows a conceptual diagram of a visual field (i) when an AA line cross section of an arbitrary one skeleton in area A of the metal porous body 10 shown in FIG. 3 is observed by SEM. Similarly, FIG. 6 shows a conceptual diagram of a visual field (iii) of the AA line cross section of the same skeleton, and FIG. 7 shows a conceptual diagram of a visual field (iii).

The thickness of the heat-resistant coating film 11 is maximized in each of the visual fields (i) to (iii) when the heat-resistant coating film 11 in the A-A line cross section of an arbitrary one skeleton in the area A is observed by SEM. The thickness (maximum thickness A (i), maximum thickness A (ii), maximum thickness A (iii)) and the thickness at which the thickness of the heat-resistant coating film 11 is minimized (minimum thickness a (i), minimum thickness a (ii)). , Minimum thickness a (iii)) is measured. The thickness of the heat-resistant coating film 11 means the thickness of the heat-resistant coating film 11 extending in the vertical direction from the surface of the nickel alloy 12.
When an alloy layer is formed between the heat-resistant coating film 11 and the nickel alloy 12, the thickness of the heat-resistant coating film 11 is the alloy layer extending vertically from the surface of the nickel alloy 12 and the heat-resistant coating. It shall mean the total thickness of the film 11.
As a result, the maximum thickness A (i) to the maximum thickness A (iii) of the three fields of view and the minimum thickness a (i) to the minimum thickness a ( iii) is decided. For Areas B, C, D, and E, the maximum thickness and the minimum thickness of the heat-resistant coating film 11 in three visual fields are measured for the AA line cross section of an arbitrary skeleton in the same manner as in Area A.
The average of the maximum thickness A (i) to the maximum thickness E (iii) and the minimum thickness a (i) to the minimum thickness e (iii) of the heat-resistant coating film 11 measured as described above is the average of the heat-resistant coating film 11. It is called the average film thickness.

The metal porous body according to the embodiment of the present disclosure preferably has a porosity of 60% or more and 98% or less. When the porosity of the metal porous body is 60% or more, the metal porous body can be made very lightweight, and further, when the metal porous body is used as a gas diffusion layer of a fuel cell, gas diffusion You can improve your sex. Further, when the porosity of the metal porous body is 98% or less, the metal porous body can be made to have sufficient strength. From these viewpoints, the porosity of the metal porous body is more preferably 70% or more and 98% or less, and further preferably 80% or more and 98% or less.
The porosity of a metal porous body is defined by the following equation.
Porosity = (1- (mass of porous material [g] / (apparent volume of porous material [cm ³ ] x material density [g / cm ³ ])) x 100 [%]

The average pore diameter of the metal porous body is preferably 50 μm or more and 1000 μm or less. When the average pore diameter is 50 μm or more, the strength of the metal porous body can be increased, and further, when the metal porous body is used as the gas diffusion layer of the fuel cell, the gas diffusibility can be increased. When the average pore diameter is 1000 μm or less, the bendability of the metal porous body can be improved. From these viewpoints, the average pore diameter of the metal porous body is more preferably 100 μm or more and 500 μm or less, and further preferably 150 μm or more and 400 μm or less.
The average pore size of the metal porous body is obtained by observing the surface of the metal porous body with a microscope or the like and counting the number of pores per inch (25.4 mm) as the number of cells, and the average pore size = 25.4 mm / number of cells. It shall mean what is calculated as.

The thickness of the metal porous body having a flat plate shape is preferably 500 μm or more and 5000 μm or less. When the thickness of the metal porous body is 500 μm or more, it is possible to obtain a metal porous body having sufficient strength and having high gas diffusion performance when used as a gas diffusion layer of a fuel cell. When the thickness of the metal porous body is 5000 μm or less, a lightweight metal porous body can be obtained. From these viewpoints, the thickness of the metal porous body is more preferably 600 μm or more and 2000 μm or less, and further preferably 700 μm or more and 1500 μm or less.

<Fuel cell>
The fuel cell according to the embodiment of the present disclosure may be provided with the metal porous body according to the above-described embodiment of the present disclosure as a gas diffusion layer, and other configurations shall be the same as those of the conventional fuel cell. Can be done. Other configurations include, for example, a solid electrolyte layer, electrode layers laminated on both sides of the solid electrolyte layer, and an interconnector with a simple gas flow path processing for more uniform gas diffusion. And so on. The metal porous body according to the embodiment of the present disclosure can act not only as a gas diffusion layer but also as a current collector.
The type of fuel cell is not limited, and may be a solid oxide fuel cell (SOFC), a polymer electrolyte fuel cell (PEFC), or a phosphoric acid fuel cell (PAFC).
Generally, a solid oxide fuel cell operates at a high temperature of about 800 ° C., and air containing oxygen is supplied to the air electrode. Therefore, the metal porous body arranged as the gas diffusion layer on the air electrode side needs to be able to exist stably even in a high temperature oxidizing atmosphere under extremely severe conditions.
Since the heat-resistant coating film is formed on the surface of the skeleton (the surface of the skeleton of the porous base material), the metal porous body according to the embodiment of the present disclosure described above is stable for a long period of time even in a high-temperature oxidizing atmosphere of about 800 ° C. Can exist in. Further, since the metal porous body according to the embodiment of the present disclosure has a high porosity, gas can be efficiently diffused when used as a gas diffusion layer. Further, since the metal porous body according to the embodiment of the present disclosure has high conductivity, it can exhibit a high function as a current collector. Therefore, the fuel cell using the metal porous body according to the embodiment of the present disclosure as the gas diffusion layer and the current collector has high power generation efficiency.

<Manufacturing method of porous metal>
The method for producing a metal porous body according to the embodiment of the present disclosure is the above-mentioned method for producing a metal porous body, which includes a preparation step of preparing a flat plate-shaped porous body base material having continuous pores and the porous body group. It has a heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the material. In another aspect, the method for producing the metal porous body includes a preparation step of preparing a porous body base material having the skeleton and the continuous pores formed by the skeleton, and the skeleton in the porous body base material. The porous body base material has a flat plate-like appearance, and the skeleton of the porous body base material has a heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the porous body. It has a nickel alloy on the surface.
Each step will be described in detail below.

(Preparation process)
The preparation step is a step of preparing a porous base material having continuous pores and having a flat plate shape as a whole. On another aspect, it can also be seen that the porous substrate has the skeleton and the continuous pores formed by the skeleton. The porous body base material is a base material (porous body base material) in the metal porous body according to the embodiment of the present disclosure, that is, a nickel alloy 12. Therefore, the porous base material prepared in this step may have a mesh-like skeleton shape such as punching metal or expanded metal, but is more preferably a three-dimensional network-like shape.
The porous base material may have at least the surface of the skeleton formed of a nickel alloy. The skeleton of the porous base material may have a hollow structure inside, or may have a structure in which a nickel alloy is formed on the surface of the resin molded body.

The nickel alloy may be the same as the nickel alloy in the metal porous body according to the embodiment of the present disclosure described above. That is, the nickel alloy may contain an alloy of nickel and a metal other than nickel as a main component, and may intentionally or inevitably contain a component other than the alloy of nickel and a metal other than nickel. The nickel alloy is preferably an alloy of nickel and any one or more metals selected from the group consisting of tungsten, molybdenum, aluminum and titanium.

FIG. 8 shows an enlarged schematic view of an example of a porous base material having a skeleton having a three-dimensional network structure in an enlarged view. As shown in FIG. 8, the skeleton 83 of the porous base material 80 is formed of a nickel alloy 82. The porous base material 80 has a skeleton having a three-dimensional network structure, and the inside 84 of the skeleton 83 is hollow. Further, the porous base material 80 has continuous pores, and the pore portion 85 is formed by the skeleton 83.
FIG. 9 shows an enlarged schematic view of another example of a porous base material having a skeleton having a three-dimensional network structure, which is an enlarged view of a cross section. As shown in FIG. 9, the skeleton 93 of the porous base material 90 has a structure in which the nickel alloy 92 is formed so as to cover the surface of the skeleton of the resin molded body 96 having the skeleton of the three-dimensional network structure. Further, the porous base material 90 has continuous pores, and the pore portion 95 is formed by the skeleton 93.

Since the metal porous body according to the embodiment of the present disclosure is formed by forming a heat-resistant coating film on the surface of the skeleton of the porous body base material, the porosity and the average pore diameter of the metal porous body are each set to the porous body base material. Porosity and average porosity are approximately equal to. Therefore, the porosity and the average pore diameter of the porous base material may be appropriately selected according to the porosity and the average pore diameter of the metal porous body to be manufactured. The porosity and average pore size of the porous body substrate are defined in the same manner as the porosity and average pore size of the metal porous body according to the embodiment of the present disclosure described above.

If the desired porous substrate is not available on the market, it may be produced by the following method.
First, a sheet-shaped (flat plate-shaped) resin molded body having a skeleton having a three-dimensional network structure (hereinafter, also simply referred to as “resin molded body”) is prepared. As the resin molded body, a polyurethane resin, a melamine resin, or the like can be used. FIG. 10 shows a photograph of a urethane foam resin having a skeleton having a three-dimensional network structure.
Subsequently, a conductive treatment step of forming a conductive layer on the surface of the skeleton of the resin molded body is performed. The conductive treatment includes, for example, applying a conductive coating material containing conductive particles such as carbon and conductive ceramic, forming a layer made of a conductive metal such as nickel and copper by a electroless plating method, or a vapor deposition method. Alternatively, it can be carried out by forming a layer made of a conductive metal such as aluminum by a sputtering method.

Subsequently, a nickel alloy is plated using a resin molded product having a conductive layer formed on the surface of the skeleton as a base material. Plating of the nickel alloy may be performed by a known method.
Nickel tungsten is, for example, using a plating bath having nickel sulfate of 0.15 mol / L, sodium tungstate of 0.15 mol / L, and triammonium citrate of 0.3 mol / L, pH 7, bath temperature 40 ° C., current. Plating can be performed under the condition of a density of 5 A / dm ² . The current density is based on the apparent area of the base material.
Further, for nickel molybdenum, for example, using a plating bath in which nickel sulfate is 0.15 mol / L, sodium molybdate is 0.15 mol / L, and triammonium citrate is 0.3 mol / L, pH 7 and bath temperature 40 ° C. , Plating can be performed under the condition of current density of 5 A / dm ² . The current density is based on the apparent area of the base material. Here, the "apparent area of the base material" means, for example, the area of the main surface of the base material having a flat plate shape.

By forming a nickel alloy plating film on the surface of the skeleton of the resin molded product as described above, the porous body base material 90 shown in FIG. 9 can be obtained. Further, the porous base material 80 shown in FIG. 8 can be obtained by forming a nickel alloy plating film on the surface of the skeleton of the resin molded body and then removing the resin molded body by heat treatment or the like.
The porosity and the average pore diameter of the porous base material are substantially equal to the porosity and the average pore diameter of the resin molded product used as the base material. Therefore, the porosity and the average pore diameter of the resin molded product may be appropriately selected according to the porosity and the average porosity of the porous base material, which is the purpose of production. The porosity and average pore diameter of the resin molded product are defined in the same manner as the porosity and average pore diameter of the metal porous body described above.

Another method of forming a nickel alloy plating film on the surface of a resin molded body having a conductive layer formed on the surface of the skeleton is to first form a nickel plating film and then to form a plating film made of a metal other than nickel. There is also a method of alloying.
For example, in the case of forming a nickel aluminum or nickel titanium plating film as a nickel alloy, a nickel plating film is first formed on the surface of the skeleton of the resin molded body, and then an aluminum plating film or a titanium plating film is formed. Good. When a high-temperature molten salt bath is used when plating aluminum or titanium, alloying with nickel proceeds at the same time as plating aluminum or titanium, and the resin molded body disappears. When a low-temperature molten salt bath is used for plating aluminum, heat treatment may be performed after forming the aluminum plating film to alloy nickel and aluminum and remove the resin molded body.

Either electroless nickel plating or electrolytic nickel plating may be used for forming the nickel plating film, but electrolytic plating is preferable because it is more efficient. When performing electrolytic nickel plating, it may be carried out according to a conventional method. As the plating bath used for the electrolytic nickel plating treatment, known or commercially available plating baths can be used, and examples thereof include a watt bath, a chloride bath, and a sulfamic acid bath.
A conductive layer is formed by immersing a resin molded body having a conductive layer formed on the surface of the skeleton in the plating bath, connecting the resin molded body to a cathode and a nickel counter electrode plate to an anode, and energizing a direct current or a pulse intermittent current. A nickel-plated film can be formed on the surface of the.

Aluminum plating can be performed by electrolysis (molten salt electrolysis) in a molten salt bath so that the resin molded body after forming the nickel plating film acts as a cathode.
As the molten salt, for example, an electrolytic solution obtained by adding an aluminum halide to a halide-based molten salt can be used. As the halide-based molten salt, for example, a chloride-based molten salt or a fluoride-based molten salt can be used. As the chloride-based molten salt, for example, KCl, NaCl, CaCl ₂ , LiCl, RbCl, CsCl, SrCl ₂ , BaCl ₂ , MgCl _2, or a eutectic salt thereof can be used. As the fluoride-based molten salt, for example, LiF, NaF, KF, RbF, CsF, MgF ₂ , CaF ₂ , SrF ₂ , BaF _2, or a eutectic salt thereof can be used. Among the above halides, it is preferable to use a chloride-based molten salt from the viewpoint of efficiency, and among them, KCl, NaCl, and CaCl ₂ are preferably used from the viewpoint of low cost and easy availability.
Further, by using an organic molten salt which is a eutectic salt of an organic halide and an aluminum halide, an aluminum plating film can be formed at a low temperature. Examples of the organic halide include 1-ethyl-3-methylimidazolium chloride (EMIC) and butylpyridinium chloride (BPC). Examples of the aluminum halide include aluminum chloride (AlCl ₃ ).
When aluminum is plated with an organic molten salt, for example, by heating to about 600 ° C. or higher in an oxidizing atmosphere such as the atmosphere, the resin molded product is formed while alloying nickel and aluminum. Can be incinerated and removed.

Plating of titanium contains metal ions of Group 1 metals, fluoride ions, and titanium ions. For example, titanium is further dissolved in a molten salt bath containing at least one of lithium fluoride (LiF) and sodium fluoride (NaF) and at least one of lithium chloride (LiCl) and sodium chloride (NaCl). It can be carried out by molten salt electrolysis using a metal porous body containing nickel as a main component in a molten salt bath in which sodium chloride is dissolved.
The titanium ion may be Ti ⁴⁺ or Ti ³⁺ .

It is necessary to add titanium to the molten salt bath to cause a disproportionation reaction of 3Ti ⁴⁺ + Ti metal → 4Ti ³⁺ in the molten salt bath. The amount of titanium added to the molten salt bath may be an amount exceeding the minimum amount necessary for Ti ⁴⁺ in the molten salt bath to become Ti ³⁺ . By sufficiently dissolving titanium in the molten salt bath in advance, it is possible to prevent the titanium electrodeposited during the subsequent molten salt electrolysis from being dissolved in the molten salt bath.

(Heat-resistant coating film forming process)
The heat-resistant coating film forming step is a step of forming a heat-resistant coating film on the surface of the skeleton of the porous base material prepared in the above preparation step. On another aspect, the heat-resistant coating film forming step can also be understood as a step of forming the heat-resistant coating film on the surface of the porous base material prepared in the above preparation step. The method for forming the heat-resistant coating film is not limited, but it is preferably formed by plating from the viewpoint of efficient formation.
The heat-resistant coating film may be a metal or alloy that is stable in a high-temperature oxidizing atmosphere, such as silver (Ag), cobalt (Co), gold (Au), and platinum (Pt). From the viewpoint of the production cost of the metal porous body, the heat-resistant coating film is preferably silver or cobalt. On the other side, the heat resistant coating film preferably contains silver or cobalt.

-Silver plating-
The silver plating method is not particularly limited, and a known method can be used. For example, it is preferable to carry out by electroplating in a silver-based methanesulfonate plating bath. Further, it is preferable to perform silver strike plating before silver plating.

-Cobalt plating-
The method for plating cobalt is not particularly limited, but it is preferable to use the following method, for example. That is, as a cobalt plating solution, an aqueous solution having a composition of cobalt sulfate 350 g / L, cobalt chloride 45 g / L, sodium chloride 25 g / L, and boric acid 35 g / L was prepared, and the current density was 2A at room temperature (about 20 ° C.). By setting / dm ² , cobalt can be plated on the surface of the skeleton of the porous base material.

<Hydrogen production method and hydrogen production equipment>
The metal porous body according to the embodiment of the present disclosure can be suitably used for, for example, a gas diffusion layer for a fuel cell or an electrode for hydrogen production by water electrolysis. Hydrogen production methods are broadly divided into [1] alkaline water electrolysis method, [2] PEM (Polymer Electrolyte Membrance) method, and [3] SOEC (Solid Oxide Electrolyte Cell) method, all of which are metals. A porous body can be used.

The alkaline water electrolysis method of the above [1] is a method in which an anode and a cathode are immersed in a strong alkaline aqueous solution and water is electrolyzed by applying a voltage. By using a metal porous body as an electrode, the contact area between water and the electrode is increased, and the efficiency of electrolysis of water can be improved.
In the method for producing hydrogen by the alkaline water electrolysis method, the average pore diameter of the metal porous body when viewed from above (for example, when viewed from the main surface side when the appearance of the metal porous body is flat) is 100 μm. It is preferably 5000 μm or less. When the average pore diameter of the metal porous body is 100 μm or more when viewed from above, the generated hydrogen or oxygen bubbles are clogged in the pores of the metal porous body, and the contact area between water and the electrode is reduced. It can be suppressed. Further, when the average pore diameter when the metal porous body is viewed from above is 5000 μm or less, the surface area of the electrode becomes sufficiently large, and the efficiency of electrolysis of water can be improved. From the same viewpoint, it is more preferable that the average pore diameter when the metal porous body is viewed from above is 400 μm or more and 4000 μm or less.
The thickness of the metal porous body and the basis weight of the metal may cause deflection when the electrode area becomes large, and therefore may be appropriately selected depending on the scale of the equipment. The basis weight of the metal is preferably 200 g / m ² or more and 2000 g / m ² or less, more preferably 300 g / m ² or more and 1200 g / m ² or less, and 400 g / m ² or more and 1000 g. It is more preferably about / m ² or less. A plurality of metal porous bodies having different average pore diameters can be used in combination in order to achieve both the removal of air bubbles and the securing of the surface area.

The PEM method of the above [2] is a method of electrolyzing water using a solid polymer electrolyte membrane. By arranging an anode and a cathode on both sides of the solid polymer electrolyte membrane and applying a voltage while flowing water on the anode side, hydrogen ions generated by electrolysis of water are transferred to the cathode side through the solid polymer electrolyte membrane. It is a method of moving and extracting as hydrogen on the cathode side. The operating temperature is about 100 ° C. It has the same configuration as a polymer electrolyte fuel cell that generates electricity with hydrogen and oxygen and discharges water, and operates in the exact opposite direction. Since the anode side and the cathode side are completely separated, there is an advantage that high-purity hydrogen can be extracted. Since both the anode and the cathode need to allow water and hydrogen gas to pass through the electrode, the electrode needs to be a conductive porous body.

Since the metal porous body according to the embodiment of the present disclosure has a high porosity and good electrical conductivity, it can be suitably used for a polymer electrolyte fuel cell, and thus can be used for PEM-type water electrolysis. Can be suitably used. In the method for producing hydrogen by the PEM method, it is preferable that the metal porous body has an average pore diameter of 150 μm or more and 1000 μm or less when viewed from above. When the metal porous body is viewed from above, the average pore diameter is 150 μm or more, so that the generated hydrogen and oxygen bubbles are clogged in the pores of the metal porous body, and the contact area between water and the solid polymer electrolyte membrane is increased. It is possible to prevent it from becoming smaller. In addition, when the metal porous body is viewed from above, the average pore diameter is 1000 μm or less, so that sufficient water retention can be ensured, and water can be prevented from passing through before the reaction, which is efficient. Water can be electrolyzed. From the same viewpoint, the average pore diameter when the metal porous body is viewed from above is more preferably 200 μm or more and 700 μm or less, and further preferably 300 μm or more and 600 μm or less.

The thickness of the metal porous body and the basis weight of the metal may be appropriately selected depending on the scale of the equipment, but if the porosity becomes too small, the pressure loss for passing water increases, so the porosity is 30% or more. It is preferable to adjust the thickness and the basis weight of the metal so as to be. Further, in the PEM method, since the conduction between the solid polymer electrolyte membrane and the electrode is pressure-bonded, the amount of metal attached to the eye is adjusted so that the increase in electrical resistance due to deformation and creep during pressurization is within a practically acceptable range. There is a need. The basis weight of the metal is preferably 200 g / m ² or more and 2000 g / m ² or less, more preferably 300 g / m ² or more and 1200 g / m ² or less, and 400 g / m ² or more and 1000 g. It is more preferably about / m ² or less. In addition, in order to secure the porosity and achieve both electrical connection, a plurality of metal porous bodies having different average pore diameters can be used in combination.

The SOEC method of the above [3] is a method of electrolyzing water using a solid oxide electrolyte membrane, and the composition differs depending on whether the electrolyte membrane is a proton conductive membrane or an oxygen ion conductive membrane. In the oxygen ion conductive membrane, hydrogen is generated on the cathode side where water vapor is supplied, so that the hydrogen purity is lowered. Therefore, from the viewpoint of hydrogen production, it is preferable to use a proton conductive film.
By arranging anodes and cathodes on both sides of the proton conduction film and applying a voltage while introducing water vapor to the anode side, hydrogen ions generated by electrolysis of water are moved to the cathode side through the solid oxide electrolyte membrane. This is a method in which only hydrogen is taken out on the cathode side. The operating temperature is about 600 ° C. or higher and 800 ° C. or lower. It has the same configuration as a solid oxide fuel cell that generates electricity with hydrogen and oxygen and discharges water, and operates in the exact opposite direction.

Since it is necessary for both the anode and the cathode to allow water vapor and hydrogen gas to pass through the electrodes, the electrodes need to be conductive and have a porous body that can withstand a high-temperature oxidizing atmosphere, especially on the anode side. Since the metal porous body according to the embodiment of the present disclosure has a high porosity, good electrical conductivity, high oxidation resistance and heat resistance, it can be suitably used for a solid oxide fuel cell. In addition, it can be suitably used for SOEC type water electrolysis.

In the method for producing hydrogen by the SOC method, it is preferable that the metal porous body has an average pore diameter of 150 μm or more and 1000 μm or less when viewed from above. When the metal porous body is viewed from above, the average pore diameter is 150 μm or more, so that water vapor and generated hydrogen are clogged in the pores of the metal porous body, and the contact area between the water vapor and the solid oxide electrolyte membrane becomes small. It can be suppressed that it ends up. Further, when the metal porous body is viewed from above, the average pore diameter is 1000 μm or less, so that it is possible to prevent the pressure loss from becoming too low and the water vapor from passing through before sufficiently reacting. From the same viewpoint, the average pore diameter when the metal porous body is viewed from above is more preferably 200 μm or more and 700 μm or less, and further preferably 300 μm or more and 600 μm or less.

The thickness of the metal porous body and the basis weight of the metal may be appropriately selected depending on the scale of the equipment, but if the porosity becomes too small, the pressure loss for introducing water vapor increases, so the porosity is 30% or more. It is preferable to adjust the thickness and the basis weight of the metal so as to be. Further, in the SOEC method, the conduction between the solid oxide electrolyte membrane and the electrode is pressure-bonded, so it is necessary to adjust the amount of metal texture so that the increase in electrical resistance due to deformation and creep during pressurization is within a practically acceptable range. There is. The basis weight of the metal is preferably 200 g / m ² or more and 2000 g / m ² or less, more preferably 300 g / m ² or more and 1200 g / m ² or less, and 400 g / m ² or more and 1000 g. It is more preferably about / m ² or less. In addition, in order to secure the porosity and achieve both electrical connection, a plurality of metal porous bodies having different average pore diameters can be used in combination.

<Additional notes>
The above description includes the features described below.
(Appendix 1)
A method of generating hydrogen by electrolyzing water using a metal porous body as an electrode.
The metal porous body is a flat metal porous body having continuous pores, and is
The skeleton of the metal porous body has a heat-resistant coating film formed on the surface of a nickel alloy.
Method for producing hydrogen.
(Appendix 2)
The method for producing hydrogen according to Appendix 1, wherein the heat-resistant coating film is silver or cobalt.
(Appendix 3)
The method for producing hydrogen according to Appendix 1 or Appendix 2, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
(Appendix 4)
The hydrogen according to any one of Appendix 1 to Appendix 3, wherein the nickel alloy is mainly composed of an alloy of nickel and any one or more selected from the group consisting of tungsten, molybdenum, aluminum and titanium. Manufacturing method.
(Appendix 5)
The method for producing hydrogen according to any one of Appendix 1 to Appendix 4, wherein the skeleton has a three-dimensional network structure.
(Appendix 6)
The method for producing hydrogen according to any one of Supplementary note 1 to Supplementary note 5, wherein the metal porous body has a porosity of 60% or more and 98% or less.
(Appendix 7)
The method for producing hydrogen according to any one of Supplementary note 1 to Supplementary note 6, wherein the metal porous body has an average pore diameter of 50 μm or more and 5000 μm or less.
(Appendix 8)
The method for producing hydrogen according to any one of Supplementary note 1 to Supplementary note 7, wherein the metal porous body has a thickness of 500 μm or more and 5000 μm or less.
(Appendix 9)
The method for producing hydrogen according to any one of Supplementary note 1 to Supplementary note 8, wherein the water is a strong alkaline aqueous solution.
(Appendix 10)
The metal porous bodies are arranged on both sides of the solid polymer electrolyte membrane, and the solid polymer electrolyte membrane and the metal porous body are brought into contact with each other, and each metal porous body acts as an anode and a cathode, and water is placed on the anode side. The method for producing hydrogen according to any one of Supplementary note 1 to Supplementary note 8, wherein hydrogen is generated on the cathode side by supplying and electrolyzing the mixture.
(Appendix 11)
The metal porous bodies are arranged on both sides of the solid oxide electrolyte membrane, and the solid oxide electrolyte membrane and the metal porous body are brought into contact with each other, and each metal porous body acts as an anode and a cathode, and water vapor is generated on the anode side. The method for producing hydrogen according to any one of Supplementary note 1 to Supplementary note 8, wherein hydrogen is generated on the cathode side by supplying water to electrolyze water.

(Appendix 12)
A hydrogen production device that can generate hydrogen by electrolyzing water.
A flat metal porous body having continuous pores as an electrode is provided.
The skeleton of the metal porous body has a heat-resistant coating film formed on the surface of a nickel alloy.
Hydrogen production equipment.
(Appendix 13)
The hydrogen production apparatus according to Appendix 12, wherein the heat-resistant coating film is silver or cobalt.
(Appendix 14)
The hydrogen production apparatus according to Appendix 12 or Appendix 13, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
(Appendix 15)
The hydrogen according to any one of Appendix 12 to Appendix 14, wherein the nickel alloy is mainly composed of an alloy of nickel and any one or more selected from the group consisting of tungsten, molybdenum, aluminum and titanium. Manufacturing equipment.
(Appendix 16)
The hydrogen production apparatus according to any one of Supplementary note 12 to Supplementary note 15, wherein the skeleton has a three-dimensional network structure.
(Appendix 17)
The hydrogen production apparatus according to any one of Supplementary note 12 to Supplementary note 16, wherein the metal porous body has a porosity of 60% or more and 98% or less.
(Appendix 18)
The hydrogen production apparatus according to any one of Supplementary note 12 to Supplementary note 17, wherein the metal porous body has an average pore diameter of 50 μm or more and 5000 μm or less.
(Appendix 19)
The hydrogen production apparatus according to any one of Supplementary note 12 to Supplementary note 18, wherein the metal porous body has a thickness of 500 μm or more and 5000 μm or less.
(Appendix 20)
The hydrogen production apparatus according to any one of Supplementary note 12 to Supplementary note 19, wherein the water is a strong alkaline aqueous solution.
(Appendix 21)
It has anodes and cathodes on both sides of the solid polymer electrolyte membrane.
The anode and the cathode are in contact with the solid polymer electrolyte membrane, and are in contact with each other.
A hydrogen production apparatus capable of generating hydrogen on the cathode side by electrolyzing the water supplied to the anode side.
The hydrogen production apparatus according to any one of Appendix 12 to Appendix 19, wherein the metal porous body is used for at least one of the anode and the cathode.
(Appendix 22)
It has anodes and cathodes on both sides of the solid oxide electrolyte membrane.
The anode and the cathode are in contact with the solid oxide electrolyte membrane, and are in contact with each other.
A hydrogen production apparatus capable of generating hydrogen on the cathode side by electrolyzing the water vapor supplied to the anode side.
The hydrogen production apparatus according to any one of Appendix 12 to Appendix 19, wherein the metal porous body is used for at least one of the anode and the cathode.

(Appendix 101)
A flat metal porous body having continuous pores,
The skeleton of the metal porous body has a heat-resistant coating film formed on the surface of a nickel alloy.
Porous metal.
(Appendix 102)
The metal porous body according to Appendix 101, wherein the heat-resistant coating film is silver or cobalt.
(Appendix 103)
The metal porous body according to Appendix 101 or Appendix 102, wherein the heat-resistant coating film has an average film thickness of 1 μm or more.
(Appendix 104)
The metal according to any one of Appendix 101 to Appendix 103, wherein the nickel alloy is mainly composed of an alloy of nickel and any one or more selected from the group consisting of tungsten, molybdenum, aluminum and titanium. Porous body.
(Appendix 105)
The metal porous body according to any one of the items 101 to 104, wherein the skeleton has a three-dimensional network structure.
(Appendix 106)
The metal porous body according to any one of Appendix 101 to Appendix 105, wherein the metal porous body has a porosity of 60% or more and 98% or less.
(Appendix 107)
The metal porous body according to any one of Supplementary notes 101 to 106, wherein the metal porous body has an average pore diameter of 50 μm or more and 5000 μm or less.
(Appendix 108)
The metal porous body according to any one of Supplementary note 101 to Supplementary note 107, wherein the metal porous body has a thickness of 500 μm or more and 5000 μm or less.
(Appendix 109)
A fuel cell comprising the metal porous body according to any one of Supplementary notes 101 to 108 as a gas diffusion layer.
(Appendix 110)
The method for producing a metal porous body according to Appendix 101.
A preparation process for preparing a flat plate-shaped porous base material having continuous pores, and
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous base material, and
Have,
At least the surface of the skeleton of the porous substrate is formed of a nickel alloy.
A method for producing a porous metal body.
(Appendix 111)
The preparation step is performed by plating a nickel alloy on the surface of the skeleton of a flat plate-shaped resin molded product having continuous pores.
The method for producing a porous metal body according to Appendix 110.
(Appendix 112)
The method for producing a metal porous body according to Appendix 110 or Appendix 111, wherein the shape of the skeleton of the porous body base material is a three-dimensional network structure.

Hereinafter, the present invention will be described in more detail based on Examples, but these Examples are examples, and the metal porous body and the like of the present invention are not limited thereto. The scope of the present invention is indicated by the description of the claims, and includes all modifications within the meaning and scope equivalent to the description of the claims.

(Example 1)
-Preparation process-
First, as a resin molded body having a skeleton having a three-dimensional network structure, urethane foam having a thickness of 1.2 mm and a main surface size of 15 cm × 15 cm was prepared. The porosity of urethane foam was 95%, and the average pore diameter was 440 μm.
A conductive layer was formed on the surface of the skeleton by subjecting the urethane foam to a conductive treatment. The conductive treatment was carried out by applying a solvent in which carbon was dispersed and drying.
A nickel-tungsten plating film was formed on the surface of the urethane foam skeleton using urethane foam after the conductivity treatment as a base material. Nickel-tungsten plating is performed using a plating bath containing 0.15 mol / L nickel sulfate, 0.15 mol / L sodium tungstate, and 0.3 mol / L triammonium citrate, pH 7, bath temperature 40 ° C., and current. The procedure was performed under the condition of a density of 5 A / dm ² . The current density is based on the apparent area of the base material.
As a result, the porous base material No. 1 whose skeleton surface is made of nickel-tungsten. 1 was obtained.
-Heat-resistant coating film forming process-
The porous base material No. A silver plating film was formed as a heat-resistant coating film on the surface of the skeleton of No. 1, and the resin molded body (urethane foam) was further removed by heat treatment.
For silver plating, a silver plating solution having a composition of silver potassium cyanide 2 g / L and sodium cyanide 100 g / L was used, the temperature of the plating solution was 25 ° C., the current density was 2 A / dm ² , and the anode was a stainless steel plate. It was carried out by energizing for 20 minutes using. The current density is based on the apparent area of the porous base material.
As a result, the metal porous body No. 1 in which a silver plating film was formed on the surface of nickel-tungsten. 1 was obtained.

(Example 2)
-Preparation process-
The porous base material No. 1 was prepared in the same manner as in Example 1.
-Heat-resistant coating film forming process-
The porous base material No. A cobalt plating film was formed as a heat-resistant coating film on the surface of the skeleton of No. 1, and the resin molded body (urethane foam) was further removed by heat treatment.
For cobalt plating, a cobalt plating solution having a composition of cobalt sulfate 350 g / L, cobalt chloride 45 g / L, sodium chloride 25 g / L, and boric acid 35 g / L was prepared, and the current density was 2 A at room temperature (about 20 ° C.). This was done by setting / dm ² . The current density is based on the apparent area of the porous base material.
As a result, the metal porous body No. 1 in which a cobalt plating film was formed on the surface of nickel-tungsten. 2 was obtained.

(Example 3)
-Preparation process-
First, as a resin molded body having a skeleton having a three-dimensional network structure, urethane foam having a thickness of 1.2 mm and a main surface size of 15 cm × 15 cm was prepared. The porosity of urethane foam was 95%, and the average pore diameter was 440 μm.
A conductive layer was formed on the surface of the skeleton by subjecting the urethane foam to a conductive treatment. The conductive treatment was carried out by applying a solvent in which carbon was dispersed and drying.
A nickel molybdenum plating film was formed on the surface of the urethane foam skeleton using urethane foam after the conductivity treatment as a base material. Nickel molybdate plating is performed using a plating bath containing 0.15 mol / L nickel sulfate, 0.15 mol / L sodium molybdate, and 0.3 mol / L triammonium citrate, pH 7, bath temperature 40 ° C., and current. The procedure was performed under the condition of a density of 5 A / dm ² . The current density is based on the apparent area of the base material.
As a result, the porous base material No. 1 whose skeleton surface is composed of nickel molybdenum. 2 was obtained.
-Heat-resistant coating film forming process-
The porous base material No. A silver plating film was formed as a heat-resistant coating film on the surface of the skeleton of No. 2, and the resin molded body (urethane foam) was further removed by heat treatment.
The formation of the silver plating film and the heat treatment were carried out in the same manner as in Example 1.
As a result, the metal porous body No. 1 in which a silver plating film was formed on the surface of nickel molybdenum. 3 was obtained.

(Example 4)
-Preparation process-
A porous base material No. 2 was prepared in the same manner as in Example 3.
-Heat-resistant coating film forming process-
The porous base material No. A cobalt plating film was formed as a heat-resistant coating film on the surface of the skeleton of No. 2, and the resin molded body (urethane foam) was further removed by heat treatment.
The formation of the cobalt plating film and the heat treatment were carried out in the same manner as in Example 3.
As a result, the metal porous body No. 1 in which a cobalt plating film was formed on the surface of nickel molybdenum. 4 was obtained.

-Evaluation-
The metal porous body No. produced in the examples. 1-No. For No. 4, the high temperature oxidation resistance and resistance were evaluated as follows. For reference, the porous base material No. 1 and No. Similarly, the high temperature oxidation resistance and resistance of No. 2 were evaluated.

(appearance)
Metal porous body No. 1-No. The porosity of No. 4 was 94%, and the average porosity was 430 μm.
In addition, the metal porous body No. 1-No. The cross section of the skeleton of No. 4 was observed by SEM, and the average film thickness of the heat-resistant coating film was measured as described above. As a result, the metal porous body No. The average film thickness of the heat-resistant coating film No. 1 was 20 μm, and the metal porous body No. 2 is 10 μm, and the metal porous body No. 3 is 20 μm, and the metal porous body No. 4 was 10 μm.

(High temperature oxidation resistance)
Metal porous body No. 1-No. 4 and the porous base material No. 1, No. 2 was heat-treated in the air at 800 ° C. for 500 hours.
Metal porous body No. after heat treatment. 1-No. 4 and the porous base material No. 1, No. The skeleton of No. 2 was visually observed.
As a result, the porous base material No. in which the heat-resistant coating film was not formed on the surface of the skeleton. 1 and No. No. 2 had cracks and cracks in a part of the skeleton and was fragile. On the other hand, the metal porous body No. 1-No. No. 4 had no abnormality in the skeleton even after the heat treatment and maintained sufficient strength.

(Resistance measurement)
As in the case of measuring the strength, the metal porous body No. 1-No. 4 and the porous base material No. 1, No. 2 was heat-treated.
Metal porous body No. after heat treatment. 1-No. 4 and the porous base material No. 1, No. For No. 2, the electrical resistance was measured.
For the measurement of the electric resistance, the size of the test piece was 4 cm × 4 cm, and the electric resistance in the thickness direction was measured at 800 ° C. by the four-terminal method. The results are shown in Table 1.

From Table 1, the metal porous body No. 1-No. No. 4 is a porous base material No. 1 and No. Compared with 2, it showed an extremely low resistance value even at a high temperature of 800 ° C., indicating that it can be suitably used as a current collector for SOFCs.

10 metal porous body, 11 heat resistant coating film, 12 nickel alloy, 13 skeleton, 14 skeleton inside, 15 pores, 80 porous base material, 82 nickel alloy, 83 skeleton, 84 skeleton inside, 85 pores, 90 porous Body base material, 92 nickel alloy, 93 skeleton, 95 pores, 96 resin molded body.

Claims (12)

A metal porous body having a porous body base material and a heat-resistant coating film.
The porous base material is
A skeleton with a nickel alloy on the surface and
It has continuous pores formed by the skeleton and
The heat-resistant coating film covers the surface of the skeleton and
The metal porous body has a flat plate-like appearance.
Porous metal. The metal porous body according to claim 1, wherein the heat-resistant coating film contains silver or cobalt. The metal porous body according to claim 1 or 2, wherein the heat-resistant coating film has an average film thickness of 1 μm or more. The nickel alloy according to any one of claims 1 to 3, wherein the nickel alloy contains an alloy of nickel and any one or more metals selected from the group consisting of tungsten, molybdenum, aluminum and titanium as a main component. The described metal porous body. The metal porous body according to any one of claims 1 to 4, wherein the shape of the skeleton is a three-dimensional network structure. The metal porous body according to any one of claims 1 to 5, wherein the metal porous body has a porosity of 60% or more and 98% or less. The metal porous body according to any one of claims 1 to 6, wherein the metal porous body has an average pore diameter of 50 μm or more and 1000 μm or less. The metal porous body according to any one of claims 1 to 7, wherein the metal porous body has a thickness of 500 μm or more and 5000 μm or less. A fuel cell comprising the metal porous body according to any one of claims 1 to 8 as a gas diffusion layer. The method for producing a porous metal body according to any one of claims 1 to 8.
A preparation step of preparing a porous base material having the skeleton and the continuous pores formed by the skeleton, and
A heat-resistant coating film forming step of forming a heat-resistant coating film on the surface of the skeleton of the porous substrate,
Have,
The porous substrate has a flat plate-like appearance.
The skeleton of the porous substrate has a nickel alloy on its surface.
A method for producing a porous metal body. The preparation step is performed by plating a nickel alloy on the surface of a skeleton and a resin molded body having continuous pores formed by the skeleton.
The resin molded body has a flat plate-like appearance.
The method for producing a porous metal body according to claim 10. The method for producing a metal porous body according to claim 10 or 11, wherein the shape of the skeleton of the porous body base material is a three-dimensional network structure.