Conductive member and solid oxide fuel cell including same

Abstract

This conductive member includes a porous body having a skeleton with a three-dimensional network structure. The porous body has a plate shape comprising a first main surface and a second main surface opposite from the first main surface; the first main surface contains carbon atoms; the porous body is an NiCrAl metal porous body or an NiCrAlFe metal porous body.

Description

Conductive member and solid oxide fuel cell including same

[0001] The present disclosure relates to a conductive member and a solid oxide fuel cell including the same. This application claims priority to Japanese Patent Application No. 2022-155329 filed on September 28, 2022, and incorporates by reference all of the contents of said Japanese application.

[0002] Conventionally, conductive members including porous bodies containing nickel, chromium, and aluminum, or porous bodies containing nickel, chromium, iron, and aluminum, have been used in solid oxide fuel cells (Patent Document 1, Patent Document 2).

[0003] International Publication No. 2016 / 021988 JP 6-29024 Publication

[0004] An electrically conductive member according to one aspect of the present disclosure includes a porous body having a skeleton with a three-dimensional mesh structure, the porous body having a plate-like shape with a first main surface and a second main surface opposite to the first main surface, the first main surface containing carbon atoms, and the porous body being a NiCrAl porous metal body or a NiCrAlFe porous metal body.

[0005] A solid oxide fuel cell according to one aspect of the present disclosure includes the conductive member.

[0006] Fig. 1 is a schematic cross-sectional view showing an example of a conductive member according to one aspect of the present disclosure. Fig. 2 is a schematic enlarged view of region II in Fig. 1. Fig. 3 is a schematic enlarged view of region III in Fig. 2. Fig. 4 is a schematic enlarged view of region IV in Fig. 1. Fig. 5 is a schematic cross-sectional view showing an example of a solid oxide fuel cell of an embodiment. Fig. 6 is a schematic view showing a method for measuring the value of contact resistance.

[0007] [Problem to be Solved by the Present Disclosure] In a solid oxide fuel cell, the surface of a conductive member is in contact with a connecting member (interconnector). The conductive member is a porous body containing nickel, chromium, and aluminum, or a porous body containing nickel, chromium, iron, and aluminum. Metal oxidation progresses with use, forming oxides on the surface region of the conductive member. The generation of oxides increases the contact resistance between the conductive member and the connecting member (interconnector), sometimes resulting in a decrease in output.

[0008] The present disclosure aims to provide a conductive member that, when used in a solid oxide fuel cell, suppresses an increase in contact resistance that accompanies use of the solid oxide fuel cell, and a solid oxide fuel cell that suppresses a decrease in output performance and has excellent output performance.

[0009] [Advantages of the Present Disclosure] According to the present disclosure, it is possible to provide a conductive member that, when used in a solid oxide fuel cell, suppresses an increase in contact resistance that accompanies use of the solid oxide fuel cell, and a solid oxide fuel cell that suppresses a decrease in output performance and has excellent output performance.

[0010] [Description of Embodiments of the Present Disclosure] First, embodiments of the present disclosure will be listed and described. [1] A conductive member according to one aspect of the present disclosure includes a porous body having a skeleton with a three-dimensional network structure, the porous body having a plate-like shape with a first main surface and a second main surface opposite to the first main surface, the first main surface containing carbon atoms, and the porous body being a NiCrAl porous metal body or a NiCrAlFe porous metal body.

[0011] When used in a solid oxide fuel cell, the conductive member according to one aspect of the present disclosure suppresses an increase in contact resistance that accompanies use of the solid oxide fuel cell, and therefore the solid oxide fuel cell including the conductive member can suppress a decrease in output performance and have excellent output performance.

[0012] [2] In the above [1], the carbon atoms may be present in the form of conductive carbon. When used in a solid oxide fuel cell, the conductive member according to one aspect of the present disclosure suppresses an increase in contact resistance that accompanies use of the solid oxide fuel cell. Therefore, a solid oxide fuel cell including the conductive member can suppress a decrease in output performance and have excellent output performance.

[0013] [3] In the above [1] or [2], the skeleton may have a first region, the first region being a region from the first main surface to a plane parallel to the first main surface, the distance from the first main surface to the plane being 10 nm, and the carbon atom content in the first region may be 10 atm% or more and 90 atm% or less. This allows the conductive member according to one aspect of the present disclosure to further reduce contact resistance when used in a solid oxide fuel cell. Therefore, a solid oxide fuel cell including the conductive member can further suppress a decrease in output performance and have better output performance.

[0014] [4] In the above [3], the content may be 20 atm % or more and 80 atm % or less. When used in a solid oxide fuel cell, the conductive member according to one aspect of the present disclosure suppresses an increase in contact resistance that accompanies use of the solid oxide fuel cell. Therefore, a solid oxide fuel cell including the conductive member can suppress a decrease in output performance and have excellent output performance.

[0015] [5] In the above [3], the content may be 30 atm% or more and 70 atm% or less. When used in a solid oxide fuel cell, the conductive member according to one aspect of the present disclosure suppresses an increase in contact resistance that accompanies use of the solid oxide fuel cell. Therefore, a solid oxide fuel cell including the conductive member can suppress a decrease in output performance and have excellent output performance.

[0016] [6] In any one of the above [1] to [5], the thickness of the porous body may be 0.2 mm or more and 2 mm or less. The conductive member according to one aspect of the present disclosure has both strength and good conductivity. Therefore, a solid oxide fuel cell including the conductive member can have excellent output performance.

[0017] [7] In any one of [1] to [6] above, the porous body may have an average pore diameter of 60 μm or more and 3500 μm or less. The conductive member according to one aspect of the present disclosure has both good conductivity and air permeability. Therefore, a solid oxide fuel cell including the conductive member can have excellent output performance.

[0018] [8] In the above [7], the porous body may have an average pore diameter of 100 μm or more and 850 μm or less. The conductive member according to one aspect of the present disclosure has both good conductivity and air permeability. Therefore, a solid oxide fuel cell including the conductive member can have excellent output performance.

[0019] [9] In any one of the above [1] to [8], the porous body may have an average porosity of 50% or more and 98% or less. The conductive member according to one aspect of the present disclosure has both good strength and light weight. Therefore, a solid oxide fuel cell including the conductive member can have excellent strength and light weight.

[0020]

[10] In any one of [1] to [9] above, in the NiCrAl porous metal body, the skeletal body may contain Ni, Cr, and Al in a total amount of 55 mass% or more. The conductive member according to one aspect of the present disclosure has excellent corrosion resistance and heat resistance. When used in a solid oxide fuel cell, an increase in resistance is suppressed. Therefore, a solid oxide fuel cell including the conductive member can suppress a decrease in output performance and have excellent output performance.

[0021]

[11] In any one of [1] to [9] above, in the NiCrAlFe metal porous body, the skeletal body may contain a total of 55 mass% or more of Ni, Cr, Al, and Fe. The conductive member according to one aspect of the present disclosure has excellent corrosion resistance and heat resistance. When used in a solid oxide fuel cell, an increase in resistance is suppressed. Therefore, a solid oxide fuel cell including the conductive member can suppress a decrease in output performance and have excellent output performance.

[0022]

[12] A solid oxide fuel cell according to an embodiment of the present disclosure includes the conductive member according to any one of the above [1] to

[11] . This allows the solid oxide fuel cell according to an embodiment of the present disclosure to have excellent output performance.

[0023]

[13] In the above

[12] , the first main surface may be in contact with at least one of a first interconnector and a second interconnector, which will be described later. This allows the solid oxide fuel cell according to one aspect of the present disclosure to have excellent output performance.

[0024] [Details of the embodiment of the present disclosure] A specific example of a conductive member according to one embodiment of the present disclosure (hereinafter also referred to as "the present embodiment") and a solid oxide fuel cell including the same will be described below with reference to the drawings. In the drawings of the present disclosure, the same reference numerals represent the same or corresponding parts. Furthermore, dimensional relationships such as length, width, thickness, and depth have been changed as appropriate for clarity and simplification of the drawings, and do not necessarily represent actual dimensional relationships.

[0025] In this specification, when a compound (alloy) is expressed by a chemical formula that does not limit the composition ratio of the constituent elements, such as "NiCrAl," the chemical formula is considered to include all known composition ratios (element ratios). Furthermore, the above chemical formula includes not only stoichiometric compositions but also non-stoichiometric compositions. For example, the chemical formula of "NiCrAl" does not include the stoichiometric composition "Ni １ Cr １ Al １ " as well as, for example, "Ni １ Cr １ Al ０．８ This also applies to compounds other than "NiCrAl."

[0026] [Embodiment 1: Conductive Member] A conductive member according to one embodiment of the present disclosure will be described with reference to Figures 1 to 4. A conductive member 3 according to one embodiment of the present disclosure (hereinafter also referred to as "this embodiment") is a conductive member 3 including a porous body 10 having a skeleton 11 with a three-dimensional network structure, wherein the porous body 10 has a plate-like shape having a first main surface 1 and a second main surface 2 opposite to the first main surface 1, the first main surface 1 contains carbon atoms, and the porous body 10 is a NiCrAl porous metal body or a NiCrAlFe porous metal body.

[0027] <Porous Body> <Shape of Porous Body> The conductive member 3 of the present disclosure includes a porous body 10 having a skeleton 11 with a three-dimensional network structure. In the present disclosure, the three-dimensional network structure may be the same as the structure described in paragraphs 0047 to 0054 of the specification of WO 2019 / 244480. In the present disclosure, the skeleton may be the same as the structure described in paragraphs 0034 to 0036 of the specification of WO 2019 / 244480. For example, as shown in FIGS. 2 and 4 , the porous body 10 has a three-dimensional network structure including a skeleton 11 and pores 14. The skeleton 11 includes a skeleton main body 15 and a hollow interior 13 surrounded by the skeleton main body 15. The conductive member 3 of the present disclosure includes a porous body 10 having a skeleton 11 with a three-dimensional network structure.

[0028] The skeleton 11 has a hollow cylindrical portion 13 surrounded by the skeleton body 15. The cross section perpendicular to the extension direction of the cylindrical shape may be triangular or other polygonal, or may be circular. Because the skeleton 11 is cylindrical, it has an inner surface 22 and an outer surface 21 (FIG. 4). Because the skeleton 11 has a hollow interior 13 surrounded by the skeleton body 15, the porous body 10 can be made very lightweight (i.e., the conductive member 3 can be made very lightweight). However, the skeleton 11 is not limited to being hollow and may be solid. In this case, the strength of the conductive member 3 can be improved.

[0029] The porous body 10 has a plate-like shape having a first main surface 1 and a second main surface 2 opposite to the first main surface 1. The thickness of the porous body 10 may be 0.2 mm or more and 2 mm or less. When the thickness of the porous body 10 is 2 mm or less, it is possible to form a porous body 10 that is thinner than conventional porous bodies, thereby reducing the amount of metal required. When the thickness of the porous body 10 is 0.2 mm or more, it is possible to provide the necessary strength. The thickness of the porous body 10 may be 0.5 mm or more and 1 mm or less. The thickness of the porous body 10 can be measured, for example, using a commercially available digital thickness gauge (Teclock Corporation).

[0030] <Composition of Porous Body> The inclusion of carbon atoms in the first main surface 1 imparts electrical conductivity to the first main surface 1. During operation of the solid oxide fuel cell 150, oxides (nickel oxide, chromium oxide, aluminum oxide, iron oxide, NiCrAl oxide, NiCrAlFe oxide, etc.) generated on the first main surface 1 increase the contact resistance between the first main surface 1 side of the conductive member 3 and the connecting member (interconnector), but the electrical conductivity of the carbon atoms contained in the first main surface 1 suppresses the increase in contact resistance. Here, "the first main surface 1 contains carbon atoms" can also be interpreted as "at least a portion of the carbon atoms of all the carbon atoms contained in the porous body 10 are exposed to the first main surface 1."

[0031] The carbon atoms may be present in the form of conductive carbon, which improves the conductivity of the first main surface 1 and further suppresses an increase in contact resistance between the conductive member 3 and the connecting member in the solid oxide fuel cell 150. Examples of conductive carbon include carbon black (thermal black, furnace black, lamp black, channel black, acetylene black, etc.).

[0032] "The first main surface 1 contains carbon atoms" can be specified by the following method. First, in a rectangular measurement area of ​​1 μm×1 μm at any one location on the first main surface 1, area analysis is performed on the outer surface of the skeleton 11 using an Auger electron spectroscopy device (trade name "PHI 650" manufactured by Perkin-Elmer). The area analysis is performed under the following conditions in accordance with JIS K 0146:2002 (ISO 14606:2000). <Measurement conditions> Electron energy: 10 kV Electron beam current: 3 mA Incident angle to the first main surface 1: 90° (Detector: 55°) Beam diameter: 1 nm Mode: Area analysis Measurement target elements: Metal components such as nickel, chromium, aluminum, and iron, oxygen, and carbon

[0033] A similar analysis is performed on any other nine locations on the first main surface 1. If carbon atoms are detected in at least one of the total ten locations, it is determined that "the first main surface 1 contains carbon atoms." Note that it has been confirmed that, as long as measurements are performed on the same conductive member 3 using the above method, there is no variation in the measurement results even if the measurement location is changed arbitrarily.

[0034] As long as "the first main surface 1 contains a carbon atom," the second main surface 2 may or may not contain a carbon atom. "The second main surface 2 contains a carbon atom" can be determined by a method similar to the method for determining "the first main surface 1 contains a carbon atom," except that the "second main surface 2" is the object of measurement.

[0035] Furthermore, the surface (outer side surface 21) of the skeleton 11 is located in a region sandwiched between the first main surface 1 and the second main surface 2. As long as the first main surface 1 contains carbon atoms, the surface (outer side surface 21) of the skeleton 11 that does not constitute the first main surface 1 may or may not contain carbon atoms.

[0036] <First Region> The skeleton 11 has a first region 12, which is a region extending from the first main surface 1 to a plane parallel to the first main surface 1, the distance from the first main surface 1 to the plane being 10 nm ( FIG. 3 ).

[0037] (Composition of First Region) The carbon atom content C1 in the first region 12 may be 10 atm% or more and 90 atm% or less. This further reduces the contact resistance between the conductive member 3 and the contact member when the first main surface 1 and the connecting member are in contact with each other. Setting the upper limit of C1 to 90 atm% or less can prevent carbon from being desorbed from the skeleton surface and blocking the flow paths for various gases in the solid oxide fuel cell. The lower limit of C1 may be 20 atm% or more, or 25 atm% or more. It may also be 30 atm% or more. The upper limit of C1 may be 80 atm% or less, 70 atm% or less, or 60 atm% or less. C1 may be 20 atm% or more and 80 atm% or less, 25 atm% or more and 70 atm% or less, or 30 atm% or more and 60 atm% or less. The contact resistance between the conductive member 3 and the contact member can be further reduced.

[0038] The carbon atom content in the first region 12 is measured using an Auger electron spectrometer. Starting from the surface of the skeleton 11, measurements are made at points at 1 nm intervals in the depth direction of the skeleton 11. The depth direction refers to the direction perpendicular to the first main surface 1. That is, measurements are made at a total of 11 points at 1 nm intervals from a distance of 0 nm to 10 nm from the surface of the skeleton 11. The measurements are made in accordance with JIS K 0146:2002 (ISO 14606:2000) under the following conditions. <Measurement conditions> Electron energy: 10 kV Electron beam current: 3 mA Incident angle to the first main surface 1: 90° (Detector: 55°) Beam diameter: 1 nm Sputter ions: Ar Mode: Depth profile analysis Elements to be measured: Metal components such as nickel, chromium, aluminum, and iron, oxygen, and carbon

[0039] The average content of carbon atoms relative to the total of carbon atoms, metal atoms (nickel atoms, chromium atoms, aluminum atoms, iron atoms, etc.), and oxygen atoms at each point is calculated to determine the average content of carbon atoms located in the depth direction at any one point on first main surface 1. Furthermore, a similar analysis is performed on any other four points on first main surface 1. C1 is determined by calculating the average content of carbon atoms at a total of five points.

[0040] It has been confirmed that as long as the same conductive member 3 is measured by the above method, there is no variation in the measurement results even if the measurement area is changed arbitrarily.

[0041] <Types of Porous Body> (Porous Metal Body) The porous body 10 is a NiCrAl porous metal body or a NiCrAlFe porous metal body. This improves the conductivity of the conductive member 3. Therefore, a solid oxide fuel cell 150 including the conductive member 3 can have excellent output performance. Here, the NiCrAl porous metal body refers to a porous body 10 in which the main body of the skeleton 11 contains Ni, Cr, and Al as main components, but does not contain Fe. The NiCrAlFe porous metal body refers to a porous body 10 in which the main body of the skeleton 11 contains Ni, Cr, Al, and Fe as main components. Here, "the main body of the skeleton 11 contains Ni, Cr, and Al as main components" means that the total content of Ni, Cr, and Al in the main body of the skeleton 11 exceeds 50 mass%. Furthermore, "the main body of skeleton 11 contains Ni, Cr, Al, and Fe as main components" means that the total content of Ni, Cr, Al, and Fe in the main body of skeleton 11 exceeds 50 mass%. Note that "the main body of skeleton 11 contains Ni, Cr, and Al as main components" and "the main body of skeleton 11 contains Ni, Cr, Al, and Fe as main components" are specified by adding up the "contents of each metal element in the main body of skeleton 11" determined by the method described below. Hereinafter, NiCrAl porous metal bodies and NiCrAlFe porous metal bodies are collectively referred to as "metal porous bodies" or "porous bodies."

[0042] In the NiCrAl porous metal body, the main body of the skeleton 11 may contain Ni, Cr, and Al in a total amount of 55% by mass or more, 60% by mass or more, or 65% by mass or more. This improves the corrosion resistance and heat resistance of the porous body 10 and further suppresses a decrease in electrical conductivity during use. In the NiCrAl porous metal body, the main body of the skeleton 11 may contain Ni, Cr, and Al in a total amount of 100% by mass or less, 99% by mass or less, or 98% by mass or less. In the NiCrAl porous metal body, the main body of the skeleton 11 may contain Ni, Cr, and Al in a total amount of 55% by mass or more and 100% by mass or less, 60% by mass or more and 99% by mass or less, or 65% by mass or more and 98% by mass or less.

[0043] In the NiCrAlFe porous metal body, the main body of the skeleton 11 may contain a total of 55% by mass or more, 60% by mass or more, or 65% by mass or more of Ni, Cr, Al, and Fe elements. This improves the corrosion resistance and heat resistance of the porous body 10 and further suppresses a decrease in electrical conductivity during use. In the NiCrAlFe porous metal body, the main body of the skeleton 11 may contain a total of 100% by mass or less, 99% by mass or less, or 98% by mass or less of Ni, Cr, Al, and Fe elements. In the NiCrAlFe porous metal body, the main body of the skeleton 11 may contain a total of 55% by mass or more and 100% by mass or less, 60% by mass or more and 99% by mass or less, or 65% by mass or more and 98% by mass or less of Ni, Cr, Al, and Fe elements.

[0044] As the NiCrAl metal porous body, for example, the porous body described in Patent Document 2 (JP-A-6-29024) and the porous body described in the specification of WO 2019 / 244480 can be used, in which the skeletal composition is changed to NiCrAl.

[0045] As the NiCrAlFe metal porous body, for example, a porous body described in Patent Document 2 and a porous body described in the specification of International Publication No. 2019 / 244480 in which the skeletal composition is changed to NiCrAlFe can be used.

[0046] The content of each metal element and oxygen in the main body of the skeleton 11 can be determined by the following procedure. First, the portion where the skeleton 11 extends is identified, and an observation image of a cross section perpendicular to the extension direction of the skeleton 11 is obtained using an electron microscope (SEM). Next, analysis is performed using an EDX device attached to the SEM. For example, a "SUPRA35VP" product name manufactured by Carl Zeiss Microscopy K.K. is used as the SEM. For example, an "Octane Super" product name manufactured by Ametec Co., Ltd. is used as the EDX device. Based on the atomic concentration of each element detected by the EDX device, the mass percentage and mass ratio of oxygen and each metal element in the main body 15 can be determined.

[0047] It has been confirmed that as long as measurements are made on the same skeleton 11 using the above method, there is no variation in the measurement results even if the measurement area is changed arbitrarily.

[0048] The main body of the skeleton 11 may contain other elements as constituent elements as long as they do not affect the effects of the conductive member 3 of the present disclosure. The main body of the skeleton 11 may contain other elements such as silicon, magnesium, carbon, sodium, tungsten, titanium, phosphorus, boron, silver, gold, molybdenum, nitrogen, sulfur, fluorine, or chlorine. These components may be contained as inevitable impurities that are inevitably mixed in during the manufacturing method described below. The content of each of the other elements in the main body of the skeleton 11 is preferably 5% by mass or less, and may be 1% by mass or less in total. The content of the other elements in the main body of the skeleton 11 can be measured using the same method as the "content of each metal element in the main body of the skeleton 11."

[0049] It has been confirmed that as long as measurements are made on the same skeleton 11 using the above method, there is no variation in the measurement results even if the measurement area is changed arbitrarily.

[0050] <Weight of Skeleton> The skeleton 11 of the NiCrAl porous metal body has a total weight of nickel, chromium, and aluminum of 200 g / m ２ More than 1000g / m ２ This allows the porous body 10 to have both strength and weight reduction. The total basis weight of nickel, chromium, and aluminum may be 250 g / m or less. ２ 900g / m or more ２ This can further improve both the strength and the weight of the porous body 10. The total basis weight of nickel, chromium, and aluminum can be adjusted appropriately by changing the amount of slurry applied in the method for producing the NiCrAl porous metal body.

[0051] The total basis weight of nickel, chromium, and aluminum can be converted into the mass per unit volume of the skeleton (apparent density of the skeleton) as follows: That is, the "apparent density of the skeleton" is 0.14 g / cm ３ 0.75g / cm or more ３ or less, and may be 0.18 g / cm ３ 0.65g / cm or more ３ Here, the "skeleton apparent density" is defined by the following formula: Skeleton apparent density [g / cm ３ ]=M[g] / V[cm ３ ] M: Mass of skeleton [g] V: Volume of the external shape of the skeleton [cm ３ ].

[0052] The skeleton 11 of the NiCrAlFe porous metal body has a total basis weight of nickel, chromium, aluminum, and iron of 200 g / m ２ More than 1000g / m ２ This allows the porous body 10 to have both strength and weight reduction. The total basis weight of nickel, chromium, aluminum, and iron may be 250 g / m or less. ２ 900g / m or more ２This can further improve both the strength and the weight of the porous body 10. The total basis weight of nickel, chromium, aluminum, and iron can be adjusted appropriately by changing the amount of slurry applied in the method for producing a NiCrAlFe metal porous body.

[0053] The total basis weight of nickel, chromium, aluminum, and iron can be converted into the mass per unit volume of the skeleton (apparent density of the skeleton) as follows. That is, the "apparent density of the skeleton" is 0.14 g / cm ３ 0.75g / cm or more ３ or less, and may be 0.18 g / cm ３ 0.65g / cm or more ３ It may be the following:

[0054] <Porosity of Porous Body> The porosity of the NiCrAl porous metal body and the NiCrAlFe porous metal body may be 40% or more and 98% or less, 45% or more and 98% or less, or 50% or more and 98% or less. When the porosity of the porous body 10 is 40% or more, the porous body 10 can be made very lightweight and the surface area of ​​the porous body 10 can be increased. When the porosity of the porous body 10 is 98% or less, the porous body 10 can be provided with sufficient strength. The porosity of the porous body 10 can be appropriately adjusted by adjusting the porosity of the foamed resin used.

[0055] The porosity of the porous body 10 is defined by the following formula: Porosity [%] = [1 - {M / (V x d)}] x 100, where M is the mass of the porous body [g] and V is the volume of the external shape of the porous body [cm ３ d: density of the metal constituting the porous body [g / cm ３ ]

[0056] <Pore diameter of porous body> The average pore diameter of the NiCrAl porous metal body and the NiCrAlFe porous metal body may be 60 μm or more and 3500 μm or less. When the average pore diameter of the porous body 10 is 60 μm or more, the strength of the porous body 10 can be increased. When the average pore diameter of the porous body 10 is 3500 μm or less, the bendability (bending processability) of the porous body 10 can be improved. From these viewpoints, the average pore diameter of the porous body 10 may be 80 μm or more and 1000 μm or less, or 100 μm or more and 850 μm or less. This can further increase the strength and bendability of the porous body 10. The average pore diameter of the porous body 10 can be appropriately adjusted by adjusting the pore diameter of the foamed resin used.

[0057] The average pore diameter of the porous body 10 can be determined by the following method. First, the portion of the porous body 10 where the skeleton 11 extends is identified. The porous body 10 is cut perpendicularly to the extension direction of the skeleton 11 to expose a cross section of the porous body 10. One of the cut cross sections is selected and observed under an electron microscope at a magnification of 3000 times to obtain an observation image. At least 10 observation images are prepared, and the number of pores per inch (25.4 mm = 25,400 μm) is determined in each of the 10 fields of view. Furthermore, the number of pores in these 10 fields of view is taken as the average value (nc), and the value calculated by substituting this value into the following formula is taken as the average pore diameter of the porous body 10. Average pore diameter [μm] = 25,400 [μm] / nc

[0058] Here, the porosity of the skeleton 11 and the porosity of the porous body 10 refer to the same thing. Also, the average pore diameter of the skeleton 11 and the average pore diameter of the porous body 10 refer to the same thing.

[0059] <Thickness of Skeleton Main Body> In the skeleton 11 of the NiCrAl porous metal body and the NiCrAlFe porous metal body, the thickness of the skeleton main body 15 may be 10 μm or more and 50 μm or less. Here, the "thickness of the skeleton main body 15" refers to the average value of the shortest distance from the inner surface 22 of the skeleton main body 15 to the outer surface 21 of the skeleton main body 15. The thickness of the skeleton main body 15 can be determined by observing a cross section of the skeleton 11 with an electron microscope. The thickness of the skeleton main body 15 can be adjusted appropriately by adjusting the thickness of the foamed resin used.

[0060] Specifically, the thickness of the skeletal body 15 can be determined by the following method. First, the portion of the porous body 10 where the skeleton 11 extends is identified. The porous body 10 is cut perpendicularly to the extension direction of the skeleton 11 to expose a cross section of the skeletal body 15. One of the cut cross sections is selected and observed under an electron microscope at a magnification of 3000 times to obtain an observation image. Next, the thickness of the skeletal body 15 is measured at 10 points in the observation image. Next, the average of the measurements at the 10 points is calculated. The average corresponds to the thickness of the skeletal body 15 of the present disclosure.

[0061] <<Method for manufacturing conductive member>> The conductive member 3 according to this embodiment can be manufactured, for example, by the following method. That is, the conductive member 3 can be manufactured by a method for manufacturing the conductive member 3, including, in this order: a first step of preparing a plate-shaped porous body and a conductive paste in which conductive carbon particles are dispersed in a solvent; a second step of obtaining a conductive member precursor by bringing the conductive paste into contact with the porous body; and a third step of performing a heat treatment on the conductive member precursor to obtain the conductive member 3. The first step includes a 1A step of preparing a plate-shaped porous body and a 1B step of preparing a conductive paste in which conductive carbon particles are dispersed in a solvent.

[0062] <Step 1> (Step 1A) In step 1A, a first porous body made of NiCrAl or NiCrAlFe is prepared as a plate-shaped porous body. The first porous body can be a commercially available one, a porous body described in Patent Document 2 (JP-A-6-29024), or a porous body described in the specification of International Publication No. 2019 / 244480, in which the skeleton composition is changed to NiCrAl or NiCrAlFe. The first porous body made of NiCrAl and the first porous body made of NiCrAlFe can also be manufactured, for example, by the following method.

[0063] Regarding the method for producing a first porous body made of NiCrAl, first, Ni powder, Cr powder, and Al powder (each having a particle size of less than 100 μm), a solvent, and a binder are uniformly mixed in a predetermined mixing ratio to prepare a slurry. Examples of solvents include, but are not limited to, water, ethanol, methanol, and N-methyl-2-pyrrolidone (NMP). Examples of binders include, but are not limited to, polyvinylidene fluoride (PVdF), polytetrafluoroethylene (PTFE), polyvinyl alcohol (PVA), and carboxymethyl cellulose (CMC). Examples of mixing methods include, but are not limited to, mixing at 400 rpm for 1 hour using a small ball mill rotating stand manufactured by Asahi Rika Seisakusho. Next, a foamed resin is immersed in the resulting slurry, and the slurry is applied to the foamed resin to obtain a first porous body precursor. Next, the first porous body precursor is heat-treated in air at 650° C. for about 15 minutes, and then heat-treated in a hydrogen atmosphere at 1000° C. for 3 hours to produce a first porous body. Note that by adjusting the ratios of Ni powder, Cr powder, and Al powder, the ratios of Ni element, Cr element, and Al element contained in the first porous body can be appropriately adjusted.

[0064] A first porous body made of NiCrAlFe can be manufactured by a similar method to that of the "Method for manufacturing a first porous body made of NiCrAl," except that, for example, "Ni powder, Cr powder, and Al powder (all with particle size less than 100 μm)" in the "Method for manufacturing a first porous body made of NiCrAl" is changed to "Ni powder, Cr powder, Al powder, and Fe powder (all with particle size less than 100 μm)." Note that by adjusting the ratios of Ni powder, Cr powder, Al powder, and Fe powder, the ratios of Ni element, Cr element, Al element, and Fe element contained in the first porous body can be appropriately adjusted.

[0065] (Step 1B) In Step 1B, a conductive paste is prepared by dispersing conductive carbon particles in a solvent. The conductive carbon particles are a source of carbon atoms contained in the first main surface 1 of the conductive member 3. Examples of conductive carbon particles include carbon black (thermal black, furnace black, lamp black, channel black, acetylene black, etc.). Examples of solvents include water, ethanol, and methanol. In the conductive paste, the conductive carbon particles may be present in an amount of 5 to 40 parts by mass per 100 parts by mass of solvent. The parts by mass of the conductive carbon particles in the conductive paste can be appropriately adjusted so that the carbon atom content C1 in the first region 12 falls within a desired numerical range. In particular, when Step 2B is performed in Step 2, it is difficult to adjust the coating thickness of the conductive paste. Therefore, the carbon atom content C1 in the first region 12 can be adjusted by appropriately adjusting the parts by mass of the conductive carbon particles in the conductive paste.

[0066] <Step 2> Next, in Step 2, a conductive paste is brought into contact with the first porous body to obtain a conductive member precursor. Specifically, the conductive member precursor can be obtained by performing, for example, either Step 2A or Step 2B below.

[0067] (Step 2A) A conductive paste is applied to at least one surface of the first porous body. Next, the solvent is evaporated from the conductive paste. This results in a conductive member precursor in which conductive carbon particles are supported on at least one surface of the porous body. Furthermore, the conductive paste may be applied to both surfaces of the first porous body. The thickness of the applied conductive paste can be appropriately adjusted so that the carbon atom content C1 in the first region 12 falls within a desired numerical range. When the conductive paste is applied to only one surface of the first porous body, the surface of the first porous body on which the conductive carbon particles are supported corresponds to the first main surface 1 of the porous body.

[0068] (Step 2B) The entire first porous body is immersed in a conductive paste, and the conductive paste is impregnated into the pores of the first porous body. Next, the solvent is evaporated from the conductive paste. This produces a conductive member precursor in which conductive carbon particles are supported on the outer surface of the skeleton of the porous body.

[0069] <Third Step> Next, the conductive member precursor is subjected to a heat treatment to obtain the conductive member 3. In the heat treatment, the temperature may be, for example, 600°C or higher and 800°C or lower. This allows the conductive carbon particles in the conductive paste to adhere to the porous body. In the heat treatment, the atmosphere may be, for example, a nitrogen atmosphere. The heat treatment time may be, for example, 10 minutes or higher and 2 hours or lower. The heat treatment atmosphere and heat treatment time affect the amount of conductive carbon particles that adhere to the porous body.

[0070] By carrying out the above steps, the conductive member 3 according to the first embodiment can be manufactured. That is, the conductive member 3 includes a porous body 10 having a skeleton 11 with a three-dimensional network structure, the porous body 10 has a plate-like shape having a first main surface 1 and a second main surface 2 opposite to the first main surface 1, the first main surface 1 contains carbon atoms, and the porous body 10 is a NiCrAl porous metal body or a NiCrAlFe porous metal body.

[0071] [Embodiment 2: Solid Oxide Fuel Cell Including Conductive Member] A solid oxide fuel cell 150 according to one embodiment of the present disclosure will be described with reference to FIG. 5 . FIG. 5 is a schematic cross-sectional view showing a solid oxide fuel cell 150 according to one aspect of the present disclosure. In FIG. 5 , the solid oxide fuel cell 150 includes a hydrogen electrode conductive member 110, a cathode conductive member 120, and a fuel cell 100. The fuel cell 100 is disposed between the hydrogen electrode conductive member 110 and the cathode conductive member 120. Here, the "hydrogen electrode conductive member 110" refers to a conductive member that supplies hydrogen to the fuel cell. The "cathode conductive member 120" refers to a conductive member that supplies an oxygen-containing gas (e.g., air) to the fuel cell. In the solid oxide fuel cell 150 of this embodiment, the cathode conductive member 120 is made of the conductive member 3 of this embodiment. That is, the solid oxide fuel cell 150 of this embodiment includes the conductive member 3 of this embodiment. This makes it possible to suppress an increase in contact resistance between the conductive member 3 and the contact member that occurs with use, and therefore makes it possible to provide a solid oxide fuel cell 150 with excellent output performance.

[0072] The fuel cell 100 may include an air electrode, a hydrogen electrode, an electrolyte layer disposed between the air electrode and the hydrogen electrode, and an intermediate layer disposed between them to prevent a reaction between the electrolyte layer and the air electrode (not shown). For example, an oxide of LaSrCo (LSC) is used as the air electrode. For example, an oxide of Zr doped with Y (YSZ) is used as the electrolyte layer. For example, an oxide of Ce doped with Gd (GDC) is used as the intermediate layer. For example, an oxide of YSZ and NiO is used as the hydrogen electrode. ２ A mixture of these is used.

[0073] 5 , the solid oxide fuel cell 150 further includes a first interconnector 112 having a fuel flow path 114 and a second interconnector 122 having an oxidant flow path 124. The fuel flow path 114 is a flow path for supplying fuel (e.g., hydrogen) to the hydrogen electrode. The fuel flow path 114 is provided on a main surface of the first interconnector 112 that faces the hydrogen electrode conductive member 110. The oxidant flow path 124 is a flow path for supplying an oxidant (e.g., oxygen) to the cathode. The oxidant flow path 124 is provided on a main surface of the second interconnector 122 that faces the cathode conductive member 120. The first interconnector 112 and the second interconnector 122 are also electrical connecting members, and in the solid oxide fuel cell 150, the surfaces of the conductive members are in contact with connecting members (interconnectors). Oxide generation increases contact resistance between the conductive members and connecting members (interconnectors), which can result in a decrease in output of the solid oxide fuel cell. In the solid oxide fuel cell of the present disclosure, contact between the first main surface of the conductive member and the interconnector suppresses an increase in contact resistance between the conductive member and the connecting member (interconnector), and thus suppresses a decrease in output of the solid oxide fuel cell.

[0074] <<Method for manufacturing a solid oxide fuel cell including a conductive member>> The solid oxide fuel cell 150 including the conductive member 3 according to this embodiment can be manufactured by appropriately using a known method, except that the conductive member 3 according to this embodiment 1 is used for the air electrode conductive member 120. Therefore, the method for manufacturing the solid oxide fuel cell 150 including the conductive member 3 should not be particularly limited, except that the conductive member 3 according to this embodiment 1 is used.

[0075] Hereinafter, the present disclosure will be specifically described based on examples, but the present invention is not limited to the following examples.

[0076] Example 1 Production of Porous Body In Example 1, porous bodies of Samples 1-1 to 1-11 were produced as follows.

[0077] <Step 1> To prepare a first porous body made of plate-shaped NiCrAl, first, 50 parts by mass of Ni powder (particle size less than 100 μm), 14 parts by mass of Cr powder (particle size less than 100 μm), 6 parts by mass of Al powder (particle size less than 100 μm), 27 parts by mass of water (solvent), and 3 parts by mass of PVdF (binder) were mixed at 400 rpm for 1 hour using a small ball mill rotating stand manufactured by Asahi Rika Seisakusho to prepare a slurry. Next, a polyurethane resin (foamed resin) was immersed in the obtained slurry, and the slurry was applied to the foamed resin to obtain a first porous body precursor. Next, the first porous body precursor was heat-treated in air at 650 ° C. for about 15 minutes, and then heat-treated in a hydrogen atmosphere at 1000 ° C. for 3 hours to prepare a first porous body made of NiCrAl (Step 1A).

[0078] Also, a conductive paste was prepared by dispersing acetylene black (conductive carbon particles) as a raw material containing carbon atoms in 100 parts by mass of distilled water (solvent) in the amount of parts by mass shown in Table 1 (Step 1B). Note that in Sample No. 1-1, the description that the distilled water (solvent) is "100 parts by mass" and the carbon black is "0 parts by mass" means that distilled water (solvent) containing no carbon black was used.

[0079] <Second Step> A conductive paste was applied to the first main surface of the first porous body, with the coating thickness adjusted so that the carbon atom content C1 in the first region was the value shown in Table 1. Next, the conductive paste applied to the first main surface was vacuum dried at 110°C to volatilize the distilled water (solvent) from the conductive paste. In this way, a conductive member precursor was obtained in which acetylene black (conductive carbon particles) was supported on the first main surface of the first porous body.

[0080] <Third Step> Next, the conductive member precursor was subjected to a heat treatment under the conditions shown in Table 1 to obtain a conductive member.

[0081]

[0082] In this manner, conductive members of Sample No. 1-1 to Sample No. 1-11 were manufactured.

[0083] <<Characteristic Evaluation of Conductive Member>> <Presence or Absence of Carbon Atoms in the First Main Surface> For the conductive members of Sample No. 1-1 to Sample No. 1-11, the presence or absence of carbon atoms in the first main surface was determined by the method described in Embodiment 1. The results obtained are shown in the "Presence or Absence of Carbon Atoms" column in Table 1. Note that "Presence" in "Presence or Absence of Carbon Atoms" means that "the first main surface contains carbon atoms," and "Absence" in "Presence or Absence of Carbon Atoms in the First Main Surface" means that "the first main surface does not contain carbon atoms."

[0084] <Composition of First Region> For the conductive members of Sample No. 1-1 to Sample No. 1-11, the carbon atom content C1 in the first region was determined by the method described in Embodiment 1. The obtained results are shown in the column "C1 [atm %]" in Table 1.

[0085] <Contact Resistance> The contact resistance of the conductive members of Sample No. 1-1 to Sample No. 1-11 was evaluated by the following method.

[0086] Two interconnector simulation plates 202 were connected to a resistance measuring device 200 (Tsuruga Electric Co., Ltd., trademark: Low Resistance Meter 356E) via platinum wires 201 for current flow. A conductive member 3 was sandwiched between the two interconnector simulation plates 202 ( FIG. 6 ). The interconnector simulation plates 202 and the conductive member 3 were then heated to 800°C in a thermostatic chamber, and the contact resistance was measured using a four-terminal method. Based on the obtained contact resistance values, the contact resistance was evaluated using a four-level scale (B to E) below. A contact resistance evaluation result of B, C, or D indicates that the contact resistance of the conductive member 3 is exceptionally low and that the conductive member 3 enables the solid oxide fuel cell to have exceptionally excellent output performance. The results are shown in the “Contact Resistance” column of Table 1. B: The contact resistance of the sample was greater than 85% and less than 90% of the contact resistance of the conductive member of Sample No. 1-1. C: The contact resistance of the sample is greater than 90% and less than 95% of the contact resistance of the conductive member of sample No. 1-1. D: The contact resistance of the sample is greater than 95% and less than 99% of the contact resistance of the conductive member of sample No. 1-1. E: Standard.

[0087] The conductive members of Sample No. 1-2 to Sample No. 1-11 correspond to Examples. On the other hand, the conductive member of Sample No. 1-1 corresponds to a Comparative Example. The conductive members of Sample No. 1-2 to Sample No. 1-11 have significantly lower contact resistance than the conductive member of Sample No. 1-1. In other words, solid oxide fuel cells including the conductive members of Sample No. 1-2 to Sample No. 1-11 can have significantly superior output performance compared to solid oxide fuel cells including the conductive member of Sample No. 1-1.

[0088] From the above, it was found that the solid oxide fuel cells provided with the conductive members of Samples No. 1-2 to 1-11 were excellent in output performance.

[0089] Example 2 <<Production of Conductive Members>> In Example 2, conductive members of Samples No. 2-1 to 2-11 were produced as follows.

[0090] <First Step> To prepare a plate-shaped first porous body made of NiCrAlFe, first, 30 parts by mass of Ni powder (particle size less than 100 μm), 13 parts by mass of Cr powder (particle size less than 100 μm), 6 parts by mass of Al powder (particle size less than 100 μm), 15 parts by mass of Fe powder (particle size less than 100 μm), 33 parts by mass of water (solvent), and 3 parts by mass of PVdF (binder) were mixed at 400 rpm for 1 hour using a small ball mill rotating stand manufactured by Asahi Rika Seisakusho Co., Ltd. to prepare a slurry. Next, a polyurethane resin (foamed resin) was immersed in the obtained slurry, and the slurry was applied to the foamed resin to obtain a first porous body precursor. Next, the first porous body precursor was heat-treated in air at 650°C for about 15 minutes, and then heat-treated in a hydrogen atmosphere at 1000°C for 3 hours to produce a first porous body made of NiCrAlFe (Step 1A).

[0091] Further, a conductive paste was prepared by dispersing acetylene black (conductive carbon particles) as a raw material containing carbon atoms in distilled water (solvent) (step 1B).

[0092] <Second Step> A conductive paste was applied to the first main surface of the first porous body, with the coating thickness adjusted so that C1 was the value shown in Table 2. Next, the conductive paste applied to the first main surface was vacuum dried at 110°C to volatilize the distilled water (solvent) from the conductive paste. In this way, a conductive member precursor was obtained in which acetylene black (conductive carbon particles) was supported on the first main surface of the first porous body.

[0093] <Third Step> The conductive member precursor was subjected to a heat treatment under the conditions shown in Table 2 to obtain a conductive member.

[0094]

[0095] In this manner, conductive members of Sample No. 2-1 to Sample No. 2-11 were manufactured.

[0096] <<Characteristic Evaluation of Conductive Member>> <Presence or Absence of Carbon Atoms in First Main Surface> For the conductive members of Sample No. 2-1 to Sample No. 2-11, the presence or absence of carbon atoms in the first main surface was evaluated in the same manner as in Example 1. The obtained results are shown in the column of "Presence or Absence of Carbon Atoms" in Table 2.

[0097] <Composition of First Region> For the conductive members of Sample No. 2-1 to Sample No. 2-11, the composition of the first region was determined by the same method as in Example 1. The obtained results are shown in the column "C1 [atm %]" in Table 2.

[0098] <Contact Resistance> The contact resistance of the conductive members of Samples No. 2-1 to 2-11 was evaluated in the same manner as in Example 1, except that the contact resistance was evaluated using a four-point scale from B' to E' as follows. The results are shown in the "Contact Resistance" column of Table 2. A contact resistance evaluation result of B', C', or D' indicates that the contact resistance of the conductive member is exceptionally low and that the conductive member can provide the solid oxide fuel cell with exceptionally excellent output performance. B': The contact resistance of the sample is greater than 85% but not greater than 90% of the contact resistance of the conductive member of Sample No. 2-1. C': The contact resistance of the sample is greater than 90% but not greater than 95% of the contact resistance of the conductive member of Sample No. 2-1. D': The contact resistance of the sample is greater than 95% but not greater than 99% of the contact resistance of the conductive member of Sample No. 2-1. E': Standard.

[0099] The conductive members of Sample No. 2-2 to Sample No. 2-11 correspond to Examples. On the other hand, the conductive member of Sample No. 2-1 corresponds to a Comparative Example. The conductive members of Sample No. 2-2 to Sample No. 2-11 have significantly lower contact resistance than the conductive member of Sample No. 2-1. In other words, solid oxide fuel cells including the conductive members of Sample No. 2-2 to Sample No. 2-11 can have significantly superior output performance compared to solid oxide fuel cells including the conductive member of Sample No. 2-1.

[0100] From the above, it was found that the solid oxide fuel cells provided with the conductive members of Samples No. 2-2 to 2-11 were excellent in output performance.

[0101] Although the embodiments and examples of the present disclosure have been described above, it is also planned from the beginning that the configurations of the above-described embodiments and examples may be appropriately combined.

[0102] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0103] REFERENCE SIGNS LIST 1 First main surface 2 Second main surface 3 Conductive member 10 Porous body 11 Skeleton 12 First region 13 Interior 14 Pore portion 15 Skeleton main body 21 Outer surface 22 Inner surface 100 Fuel cell 110 Hydrogen electrode conductive member 112 First interconnector 114 Fuel flow path 120 Air electrode conductive member 122 Second interconnector 124 Oxidant flow path 150 Solid oxide fuel cell 200 Resistance measuring device 201 Platinum wire 202 Interconnector simulation plate

Claims

1. The porous body has a three-dimensional network structure, The porous body has a plate-like shape having a first main surface and a second main surface opposite to the first main surface, the first major surface includes carbon atoms; The conductive member, wherein the porous body is a NiCrAl porous metal body or a NiCrAlFe porous metal body.

2. The conductive member according to claim 1 , wherein the carbon atoms are present in the form of conductive carbon.

3. the backbone having a first region; the first region is a region from the first main surface to a plane parallel to the first main surface, the distance from the first main surface to the plane being 10 nm; 3. The conductive member according to claim 1, wherein the content of carbon atoms in the first region is 10 atm % or more and 90 atm % or less.

4. The conductive member according to claim 3 , wherein the content is 20 atomic % or more and 80 atomic % or less.

5. The conductive member according to claim 3 , wherein the content is 30 atomic % or more and 70 atomic % or less.

6. The conductive member according to claim 1 or 2, wherein the porous body has a thickness of 0.2 mm or more and 2 mm or less.

7. The conductive member according to claim 1 or 2, wherein the average pore diameter of the porous body is 60 μm or more and 3500 μm or less.

8. The conductive member according to claim 7 , wherein the average pore diameter of the porous body is 100 μm or more and 850 μm or less.

9. 3. The conductive member according to claim 1, wherein the porous body has a porosity of 50% or more and 98% or less.

10. 3. The conductive member according to claim 1, wherein in the NiCrAl porous metal body, the skeletal body contains Ni elements, Cr elements, and Al elements in a total amount of 55 mass % or more.

11. 3. The conductive member according to claim 1, wherein in the NiCrAlFe porous metal body, the skeletal body contains Ni, Cr, Al, and Fe elements in a total amount of 55 mass % or more.

12. A solid oxide fuel cell comprising the conductive member according to claim 1 or 2.

13. 13. The solid oxide fuel cell of claim 12, wherein the first major surface is in contact with at least one of the first interconnect and the second interconnect.