Electroconductive member, fuel cell and electrolytic device

Abstract

To provide a fuel cell and an electrolytic device whose production cost can be reduced.SOLUTION: An electroconductive member 10 comprises a first layer 1 and a second layer 2. The first layer 1 is a porous body. The second layer 2 is laminated on the first layer 1. The first layer 1 is used as a current collector for a fuel cell 100 or an electrode for an electrolytic device 200. A porosity of the second layer 2 is lower than a porosity of the first layer 1. The porosity of the second layer 2 is 5% or less. The second layer 2 comprises a plurality of through holes.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a conductive member, a fuel cell, and an electrolysis device. This application claims priority to Japanese Patent Application No. 2021-120929, filed on July 21, 2021. The entire contents of the Japanese patent application are incorporated herein by reference. [Background technology]

[0002] Conventionally, devices that utilize electrochemical reactions, such as fuel cells or electrolysis devices, are known. For example, Japanese Patent Application Laid-Open No. 2021-68493 discloses a fuel cell in which a current collector made of a metal mesh is stacked and arranged so as to contact the cell electrode, and a separator having an oxidant or fuel flow path formed thereon is further stacked on the current collector. Furthermore, Japanese Patent Application Laid-Open No. 2009-149932 discloses an electrolysis device in which electrode bodies are arranged in an electrolytic cell so as to sandwich both sides of an ion-permeable diaphragm. The electrode body includes a mesh-shaped electrode member and a mesh-shaped conductor member brazed to the mesh-shaped electrode member and having an uneven surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-68493 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-149932 Summary of the Invention

[0004] The conductive member of the present disclosure includes a first layer and a second layer. The first layer has a plurality of pores dispersed therein. The second layer is laminated on the first layer. The first and second layers are used as a current collector for a fuel cell or an electrode for an electrolyzer. The porosity of the second layer is lower than that of the first layer. The porosity of the second layer is 5% or less. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a cross-sectional view of a fuel cell according to a first embodiment. [Figure 2] FIG. 2 is a partial cross-sectional schematic view of a conductive member that constitutes the fuel cell shown in FIG. [Figure 3] FIG. 3 is a partially enlarged schematic view of the first layer of the conductive member shown in FIG. [Figure 4] FIG. 4 is an enlarged schematic view of region IV in FIG. [Figure 5] FIG. 5 is an enlarged schematic view of region V in FIG. [Figure 6] FIG. 6 is a partial cross-sectional schematic view showing a first modified example of the conductive member shown in FIG. [Figure 7] FIG. 7 is a partial cross-sectional schematic view showing a second modified example of the conductive member shown in FIG. [Figure 8] FIG. 8 is a partial cross-sectional schematic view showing a third modified example of the conductive member shown in FIG. [Figure 9] FIG. 9 is a partial cross-sectional schematic view showing a fourth modified example of the conductive member shown in FIG. [Figure 10] FIG. 10 is a partial cross-sectional schematic view showing a fifth modified example of the conductive member shown in FIG. [Figure 11] FIG. 11 is a flowchart illustrating a method for manufacturing the conductive member shown in FIG. [Figure 12] FIG. 12 is a schematic diagram for explaining a method for manufacturing the conductive member shown in FIG. [Figure 13] FIG. 13 is a schematic diagram for explaining a method of manufacturing the conductive member shown in FIG. [Figure 14] FIG. 14 is a schematic diagram for explaining a method for manufacturing the conductive member shown in FIG. [Figure 15] FIG. 15 is a schematic view for explaining a method for manufacturing the conductive member shown in FIG. [Figure 16] FIG. 16 is a schematic view for explaining a method for manufacturing the conductive member shown in FIG. [Figure 17] FIG. 17 is a cross-sectional view of an electrolysis device according to the second embodiment. [Figure 18] FIG. 18 is a cross-sectional schematic view of a conductive member constituting a modified example of the electrolytic device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] In the above-mentioned conventional fuel cells and electrolysis devices, the structure around the electrodes is complex, combining multiple components, which has the disadvantage of increasing the number of parts and complicating the manufacturing process, resulting in increased manufacturing costs.

[0007] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a fuel cell and an electrolysis device that can reduce manufacturing costs. [Effects of this disclosure] According to the present disclosure, a fuel cell and an electrolysis device can be obtained that can reduce manufacturing costs.

[0008] [Description of the embodiments of the present disclosure] (1) A conductive member according to the present disclosure includes a first layer and a second layer. The first layer is porous. The second layer is laminated on the first layer. The first layer is used as a current collector for a fuel cell or an electrode for an electrolysis device. The porosity of the second layer is lower than that of the first layer. The porosity of the second layer is 5% or less.

[0009] In this way, the conductive member can be used as an assembly of a current collector connected to an electrode of a fuel cell and a partition wall layer including a gas flow path. For example, by connecting the first layer to the electrode of the cell, the second layer can function as a partition wall layer, and the first layer can function as a gas flow path and a current collector. As a result, the number of parts and manufacturing steps for the fuel cell can be reduced compared to when the current collector and partition wall layer are connected to the cell separately.

[0010] The conductive member can also be used as an electrode for an electrolysis device. For example, the first layer can function as a porous electrode for the electrolysis device, while the second layer can function as a support for the electrode. This reduces the number of parts and manufacturing steps required for the electrolysis device compared to when the electrode and support are separately installed in the electrolysis device. This reduces the manufacturing costs of the fuel cell or electrolysis device.

[0011] (2) The conductive member of (1) above may further include a third layer. The third layer may be a porous body located on the side of the second layer opposite to the side on which the first layer is located, and laminated on the second layer. The third layer may have a plurality of holes dispersed therein. The porosity of the third layer may be higher than the porosity of the second layer. The second layer may not have through-holes.

[0012] In this case, the conductive member can be alternately stacked with the fuel cell cells to easily form a fuel cell stack. For example, when the conductive member is stacked between a first cell and a second cell, the first layer acts as a gas (e.g., air) flow path and current collector for the electrode of the first cell. The third layer acts as a gas (e.g., hydrogen) flow path and current collector for the electrode of the second cell. The second layer acts as a partition layer (interconnector) that separates the first cell side from the second cell side. As a result, the manufacturing cost of the fuel cell can be reduced.

[0013] (3) In the conductive member of (2) above, the porosity of the first and third layers may be 50% or more. In this case, a sufficient gas flow rate can be ensured in the first and third layers. This can improve the performance of the fuel cell.

[0014] (4) In the conductive member of (2) or (3) above, the ratio of the total thickness of the first layer and the third layer to the total thickness of the first, second, and third layers may be 10% or more and 90% or less. The thickness of the first layer and the third layer may be substantially the same, or may be different. The configuration of the conductive member can be adjusted to suit the device configuration of the fuel cell.

[0015] (5) In the conductive members (2) to (4) above, the material constituting the first layer, the material constituting the second layer, and the material constituting the third layer may each contain at least one selected from the group consisting of nickel, cobalt, manganese, iron, copper, chromium, aluminum, zinc, titanium, tin, and alloys thereof.

[0016] In this case, when the conductive member is applied to a fuel cell or an electrolysis device, the performance of the fuel cell or the electrolysis device can be sufficiently ensured. Furthermore, the conductive member applied to the electrolysis device may be made of at least one material selected from the group consisting of nickel, nickel-aluminum (Ni-Al) alloy, nickel-zinc (Ni-Zn) alloy, and nickel-cobalt (Ni-Co) alloy, or a mixture of at least two materials selected from the above group.

[0017] (6) In the conductive members (2) to (5) above, at least one of the surface of the first layer opposite to the surface on which the second layer is located, the surface of the first layer on the surface on which the second layer is located, the surface of the third layer opposite to the surface on which the second layer is located, and the surface of the third layer on the surface on which the second layer is located may have a groove. In this case, the groove formed in the first layer or the third layer can be used as a flow path for circulating gas such as air or hydrogen.

[0018] (7) In the conductive members of (2) to (5) above, at least one of the first layer and the third layer may have through-holes. In this case, the through-holes formed in the first layer or the third layer can be used as a flow path for circulating gases such as air, hydrogen, or oxygen.

[0019] (8) In the conductive member of (1) above, the second layer may have a plurality of through-holes. In this case, for example, when the conductive member is used as an electrode of an electrolysis device, gases such as oxygen generated by electrolysis of water or the like are easily discharged to the outside of the conductive member serving as an electrode through the through-holes in the second layer.

[0020] (9) In the conductive member of (8) above, the first layer may have a plurality of recesses on its surface facing the through-holes of the second layer. In this case, when the conductive member is used as an electrode of an electrolysis device, for example, the formation of the recesses allows the surface area of ​​the portion of the first layer facing the through-holes of the second layer to be larger than when the recesses are not formed. This improves the discharge efficiency of oxygen gas, etc., generated by electrolysis of water, etc., when it is discharged to the outside of the conductive member through the through-holes of the second layer.

[0021] (10) In the conductive member of (8) or (9) above, the material constituting the first layer and the material constituting the second layer may each contain at least one selected from the group consisting of nickel, cobalt, manganese, iron, copper, chromium, aluminum, zinc, titanium, tin, and alloys thereof.

[0022] In this case, when the conductive member is applied to a fuel cell or an electrolysis device, the performance of the fuel cell or the electrolysis device can be sufficiently ensured. Furthermore, the conductive member applied to the electrolysis device may be made of at least one material selected from the group consisting of nickel, nickel-aluminum (Ni-Al) alloy, nickel-zinc (Ni-Zn) alloy, and nickel-cobalt (Ni-Co) alloy, or a mixture of at least two materials selected from the above group.

[0023] (11) In the conductive member of any one of (1) to (10) above, the first layer may have a plurality of first holes, a plurality of second holes, and a plurality of third holes. The diameter of the plurality of first holes may be 1 mm or more. The diameter of the plurality of second holes may be 100 μm or more and less than 1 mm. The diameter of the plurality of third holes may be less than 100 μm. In this case, by forming holes of various sizes as described above, the surface area of ​​the first layer can be increased.

[0024] (12) A fuel cell according to the present disclosure includes the conductive member according to any one of (2) to (7) and (11) above, which can prevent an increase in the manufacturing cost of the fuel cell.

[0025] (13) The electrolysis device according to the present disclosure includes any one of the conductive members (8) to (11) above, which can prevent an increase in the manufacturing cost of the electrolysis device.

[0026] [Details of the embodiments of the present disclosure] (Embodiment 1) <Configurations and Effects of Fuel Cells and Conductive Members> FIG. 1 is a cross-sectional view of a fuel cell 100 according to a first embodiment. FIG. 2 is a partial cross-sectional view of a conductive member 10 constituting the fuel cell 100 shown in FIG. 1. FIG. 3 is a partial enlarged view of a first layer 1 of the conductive member 10 shown in FIG. 2. FIG. 4 is an enlarged view of a region IV in FIG. 3. FIG. 5 is an enlarged view of a region V in FIG. 4. FIGS. 3 to 5 show a cross section of the conductive member 10.

[0027] As shown in FIG. 1, the fuel cell 100 has a structure (cell stack structure) in which cell structures 50 and conductive members 10 are alternately stacked. The cell structure 50 includes two electrodes (anode and cathode) and an electrolyte layer (e.g., a solid electrolyte layer) disposed between the two electrodes. The conductive member 10 includes a first layer 1 serving as a porous layer 61, a second layer 2 serving as a partition wall layer 62, and a third layer 3 serving as a porous layer 63. The second layer 2 is stacked on the first layer 1. The third layer 3 is located on the opposite side of the second layer 2 from the side on which the first layer 1 is located. The first layer 1 and the third layer 3 have a plurality of dispersed pores. The third layer 3, the second layer 2, and the first layer 1 are stacked and fixed to each other to form the conductive member 10. The first layer 1, the second layer 2, and the third layer are all made of conductors.

[0028] The first layer 1, which is a porous body, is connected to, for example, the anode of the cell structure 50. The first layer 1 serves both as a member that supplies fuel such as hydrogen to the anode and as a conductor (current collector) that has a current collecting function for the anode of the cell structure 50.

[0029] The second layer 2 stacked below the first layer 1 can function as a current collector for one cell structure 50, but here it functions as a partition wall layer 62 that separates the gas supplied to the adjacent first layer 1 from the gas supplied to the third layer. The porosity of the second layer 2 is lower than the porosity of the first layer 1 and the third layer 3. The second layer 2 does not have through holes that reach from the surface on the first layer 1 side to the surface on the third layer 3 side.

[0030] The third layer 3, which is a porous body laminated below the second layer 2, is connected to the cathode of a cell structure 50 that is different from the cell structure 50 to which the first layer 1 is connected. The third layer 3 serves both as a member that supplies air to the cathode and as a current collector for the cathode of the different cell structure 50.

[0031] As shown in FIG. 1 , by alternately stacking cell structures 50 and conductive members 10, a fuel cell 70 is formed, which includes the cell structure 50, a first layer 1 serving as a porous layer 61 connected to the anode of the cell structure 50, a second layer 2 serving as a partition wall layer 62 connected to the first layer 1, a third layer 3 serving as a porous layer 63 connected to the cathode of the cell structure 50, and the second layer 2 serving as a partition wall layer 62 connected to the third layer 3.

[0032] The porosity of the first layer 1 and the third layer 3 is 50% or more. In this case, a sufficient gas flow rate can be ensured in the first layer 1 and the third layer 3. This improves the performance of the fuel cell 100. The porosity of the first layer 1 and the third layer 3 may be 60% or more, or 70% or more. The porosity of the first layer 1 and the third layer 3 may be 40% or more, or 30% or more. The porosity of the second layer 2 is 5% or less. The porosity of the second layer 2 may be 4% or less, or 3% or less. In this case, the second layer 2 can function as a partition layer that separates the gas supplied to the first layer 1 from the gas supplied to the third layer 3.

[0033] The porosity of the first layer 1, the second layer 2 or the third layer 3 is defined by the following formula. Porosity (%) = [1-{M / (V×d)}] × 100 M: Mass [g] of the sample to be measured in the first layer 1, second layer 2, or third layer 3 V: Volume of the external shape of the sample to be measured [cm 3 ] d: density of the material constituting the measurement sample [g / cm 3 ] The "volume of the external shape" mentioned above means the apparent volume of the measurement sample, which is the total volume of the pores (air pores) in the measurement sample and the volume of the parts other than the pores. Note that the pore volume does not include the volume of grooves or through-holes formed afterwards by mechanical processing such as press working.

[0034] As described above, the conductive member 10 can be used as an assembly of current collectors connected to electrodes of the cell structure 50 of the fuel cell 100 and partition wall layers including gas flow paths. Specifically, the conductive member 10 can be alternately stacked with the cell structure 50 of the fuel cell 100 to easily form a cell stack of the fuel cell 100. As a result, the number of parts and manufacturing steps of the fuel cell 100 can be reduced compared to when the current collectors and partition wall layers are individually connected to the cell structure 50. Therefore, by using the conductive member 10, the manufacturing cost of the fuel cell 100 can be reduced.

[0035] As shown in FIG. 2 , in the conductive member 10, the ratio of the total thickness (T1 + T3) of the first layer 1 and the third layer 3 to the total thickness T4 of the thickness T1 of the first layer 1, the thickness T2 of the second layer 2, and the thickness T3 of the third layer 3 is 10% or more and 90% or less. This ratio may be 20% or more and 80% or less, or 30% or more and 70% or less. In this case, when the conductive member 10 is applied to the fuel cell 100, the first layer 1 and the third layer 3 can fully function as current collectors and as members supplying gas (fuel or air). The thickness T1 of the first layer 1 and the thickness T3 of the third layer 3 may be substantially the same, or the thickness T1 of the first layer 1 and the thickness T3 of the third layer 3 may be different. In this way, the configuration of the conductive member 10 can be adjusted to match the device configuration of the fuel cell 100.

[0036] 3 to 5, in conductive member 10 (see FIG. 1), the plurality of holes formed in first layer 1 include a plurality of first holes 1a, a plurality of second holes 1b, and a plurality of third holes 1c. The diameter of the plurality of first holes 1a, which are large holes, is, for example, 1 mm or more. The diameter of the plurality of second holes 1b, which are medium-diameter holes, is, for example, 100 μm or more and less than 1 mm.

[0037] As shown in FIG. 4, second holes 1b are formed in portions of the first layer 1 located between first holes 1a. The diameter of a plurality of small-diameter third holes 1c is, for example, less than 100 μm. As shown in FIG. 5, third holes 1c are formed in portions of the first layer 1 located between second holes 1b. Furthermore, as shown in FIG. 5, the first layer 1 may contain oxide 1d. The size of oxide 1d (e.g., the maximum width or area of ​​oxide 1d in FIG. 5) may be approximately the same as the size of third holes 1c (e.g., the maximum width or area of ​​third holes 1c in FIG. 5). Oxide 1d may be, for example, zirconia.

[0038] The plurality of holes formed in the third layer 3 may include first holes 1a, second holes 1b, and third holes 1c, similar to the first layer 1. The third layer 3 may also include an oxide 1d, similar to the first layer 1. In this case, by forming holes of various sizes (first holes 1a, second holes 1b, and third holes 1c) as described above, the surface area of ​​the first layer 1 or the third layer 3 can be increased. Furthermore, by forming first holes 1a, second holes 1b, and third holes 1c of different sizes as described above, the first layer 1 and the third layer 3 can have different functions: a function to supply gas (fuel or air) to the cell structure 50, and a function as a current collector.

[0039] The diameters of the first hole 1a, the second hole 1b, and the third hole 1c can be measured using a PORE!SCAN from Hiraizumi Yoko Co., Ltd., or by a combination of microscope observation and mercury intrusion porosimetry.

[0040] The material constituting the first layer 1, the material constituting the second layer 2, and the material constituting the third layer 3 each includes at least one selected from the group consisting of nickel (Ni), cobalt (Co), manganese (Mn), iron (Fe), copper (Cu), chromium (Cr), aluminum (Al), zinc (Zn), titanium (Ti), tin (Sn), and alloys thereof. More specifically, the material constituting the first layer 1 may include an element whose oxide crystal structure forms a spinel structure. For example, the first layer 1 may include at least one element selected from the group consisting of nickel, cobalt, manganese, iron, and copper. The material constituting the second layer 2 and the third layer 3 may be a highly heat-resistant alloy, such as an iron-chromium (Fe-Cr) alloy, typified by stainless steel. In this case, when the conductive member 10 is applied to the fuel cell 100, the performance of the fuel cell 100 can be sufficiently ensured. In other configurations, the material constituting the first layer 1, the second layer 2, and the third layer 3 may be a highly corrosion-resistant alloy, such as an Ni-Cr alloy.

[0041] <Modification> Fig. 6 is a partial cross-sectional schematic diagram showing a first modified example of the conductive member 10 shown in Fig. 2. The conductive member 10 shown in Fig. 6 basically has the same configuration as the conductive member 10 shown in Fig. 2, but differs from the conductive member 10 shown in Fig. 2 in that grooves 4 are formed in the first layer 1 and the third layer 3. In the conductive member 10 shown in Fig. 6, grooves 4 that are flow paths 41 for fuel such as hydrogen are formed on the surface 1e of the first layer 1 on the side where the second layer 2 is located. In addition, grooves 4 that are flow paths 43 for air are formed on the surface 3e of the third layer 3 on the side where the second layer 2 is located.

[0042] Fig. 7 is a partial cross-sectional schematic diagram showing a second modified example of the conductive member 10 shown in Fig. 2. The conductive member 10 shown in Fig. 7 has basically the same configuration as the conductive member 10 shown in Fig. 6, but differs from the conductive member 10 shown in Fig. 6 in the arrangement of grooves 4 formed in the first layer 1 and the third layer 3. In the conductive member 10 shown in Fig. 7, grooves 4 that serve as flow paths 41 for fuel such as hydrogen are formed on the surface 1f of the first layer 1 opposite the side on which the second layer 2 is located. In addition, grooves 4 that serve as flow paths 43 for air are formed on the surface 3f of the third layer 3 opposite the side on which the second layer 2 is located.

[0043] 8 is a partial cross-sectional schematic view showing a third modified example of the conductive member 10 shown in FIG. 2. The conductive member 10 shown in FIG. 8 basically has the same configuration as the conductive member 10 shown in FIG. 6, but the arrangement of the grooves 4 formed in the third layer 3 differs from that of the conductive member 10 shown in FIG. 6. In the conductive member 10 shown in FIG. 8, the grooves 4 serving as air flow paths 43 are formed on the surface 3f of the third layer 3 opposite the side on which the second layer 2 is located. Note that in the first layer 1, the grooves 4 serving as fuel flow paths 41 are formed on the surface 1e on the side on which the second layer 2 is located, similar to the conductive member 10 shown in FIG. 6.

[0044] 9 is a partial cross-sectional schematic diagram showing a fourth modified example of the conductive member 10 shown in FIG. 2. The conductive member 10 shown in FIG. 9 basically has the same configuration as the conductive member 10 shown in FIG. 6, but the arrangement of the grooves 4 formed in the first layer 1 differs from that of the conductive member 10 shown in FIG. 6. In the conductive member 10 shown in FIG. 9, grooves 4 serving as fuel flow paths 41 are formed on the surface 1f of the first layer 1 opposite the side on which the second layer 2 is located. Note that in the third layer 3, grooves 4 serving as air flow paths 43 are formed on the surface 3e on the side on which the second layer is located, similar to the conductive member 10 shown in FIG. 6.

[0045] In the conductive member 10 shown in FIGS. 6 to 9 , the depth of the grooves 4 need only be less than the thickness of the first layer 1 or the third layer 3, and may be 50% or less of the thickness of the first layer 1 or the third layer 3. The planar shape of the grooves 4 in a plan view perpendicular to the surface 1e of the first layer 1 can be any shape, such as a straight line, a lattice pattern, a meandering flow path shape with alternating straight and bent portions, an arc shape, or a shape combining multiple concentric circles with straight lines connecting the concentric circles. Although the grooves 4 formed in the first layer 1 and the grooves 4 formed in the third layer 3 are arranged to overlap in a plan view in FIGS. 6 to 9 , the grooves 4 formed in the first layer 1 and the grooves 4 formed in the third layer 3 may be arranged so that at least a portion of them do not overlap each other in a plan view.

[0046] Fig. 10 is a partial cross-sectional schematic view showing a fifth modified example of the conductive member shown in Fig. 2. The conductive member 10 shown in Fig. 10 basically has the same configuration as the conductive member 10 shown in Fig. 2, but differs from the conductive member 10 shown in Fig. 2 in that through holes 1g and 3g are formed in the first layer 1 and the third layer 3. In the conductive member 10 shown in Fig. 10, the through hole 1g is formed in the first layer 1, extending from the surface 1e on the second layer 2 side to the surface 1f on the opposite side from the side where the second layer 2 is located. In addition, the third layer 3 has a through hole 3g formed from the surface 3e on the second layer 2 side to the surface 3f on the opposite side from the side where the second layer 2 is located.

[0047] The planar shape of the through holes 1g, 3g may be any shape, such as a circle, a rectangle, a polygon, or an ellipse. Furthermore, in the first layer 1, grooves (not shown) connecting the plurality of through holes 1g may be formed on the surface 1e or the surface 1f. In the third layer 3, grooves (not shown) connecting the plurality of through holes 3g may be formed on the surface 3e or the surface 3f. In FIG. 10, the through holes 1g formed in the first layer 1 and the through holes 3g formed in the third layer 3 are arranged so as to overlap in a planar view, but the through holes 1g formed in the first layer 1 and the through holes 3g formed in the third layer 3 may be arranged so as not to overlap at least partially with each other in a planar view.

[0048] 6 to 10, the grooves 4 or through holes 1g, 3g formed in the first layer 1 or the third layer 3 can be used as flow paths for circulating gases such as air or hydrogen, thereby improving the performance of the fuel cell 100 to which the conductive member 10 is applied.

[0049] <Method of manufacturing conductive member> Fig. 11 is a flowchart illustrating a method for manufacturing the conductive member shown in Fig. 2. Figs. 12 to 16 are schematic views illustrating a method for manufacturing the conductive member 10 shown in Fig. 2.

[0050] 11, the method for manufacturing the conductive member 10 first performs a raw material preparation step (S10). In this step (S10), raw material powder and a binder are prepared as raw materials for the conductive member 10. As the raw material powder, a powder of the metal that constitutes the conductive member 10, a pore-forming material for forming a plurality of pores, etc. are prepared.

[0051] Next, a mixing step (S20) is carried out. In this step (S20), the raw material powder and binder prepared in the above step (S10) are mixed together to form a raw material paste.

[0052] Next, a sheet forming step (S30) is carried out. In this step (S30), the raw material paste described above is formed into a sheet to obtain a sheet member as an intermediate.

[0053] Next, a surface structure forming step (S40) is performed. In this step (S40), a surface structure such as grooves, recesses, or holes is formed on the surface of the sheet member in accordance with the application and required performance of the conductive member 10. In this step (S40), for example, as shown in FIG. 12, the sheet member 20 is processed using processing rolls 21a and 21b. As shown in FIG. 12, the processing rolls 21a and 21b are arranged opposite each other with the sheet member 20 sandwiched therebetween. A surface structure to be transferred to the surface of the sheet member 20 is formed on the surfaces of the rolls 21a and 21b. By this processing, structures such as holes, recesses, or grooves are formed in the sheet member 20. Furthermore, by using roll processing using the rolls 21a and 21b as shown in FIG. 12, the surface structure can be continuously formed on the sheet member 20. Furthermore, by rolling the sheet member 20 with the rolls 21a and 21b, the sheet member can be densified.

[0054] Next, a heat treatment step (S50) is performed. In this step (S50), the sheet member 20 with the surface structure formed thereon is heated to remove the binder from the sheet member 20 and reduce and sinter the raw material powder. If a pore-forming material is used, the pore-forming material volatilizes or thermally decomposes, forming minute pores in the sheet member. As a result, a conductive sheet having the surface structure formed in step (S40) and to constitute the conductive member 10 is obtained. Examples of conductive sheets obtained in this manner include conductive sheets 30, 31, and 32 of various shapes, as shown in FIGS. 13 to 15. For example, a conductive sheet 30 with a flat surface as shown in FIG. 13 may be obtained. Alternatively, as shown in FIG. 14, a conductive sheet 31 may be obtained in which multiple protrusions 31a are formed on the surface, resulting in groove structures 31b that will become grooves 4. Furthermore, by forming through holes in the sheet member 20 in step (S40), a conductive sheet 32 ​​may be obtained in which through holes 32g that will become through holes 1g (see FIG. 10) are formed, as shown in FIG. 15.

[0055] Next, a post-treatment step (S60) is performed. In this step (S60), the multiple conductive sheets 30, 31, and 32 obtained in the above step (S50) are combined to obtain the conductive member 10 shown in FIG. 2. For example, the conductive member 10 shown in FIG. 2 can be formed by stacking and fixing multiple conductive sheets. Alternatively, the conductive member 10 shown in FIG. 16 can be obtained by stacking and fixing the conductive sheet 31 having the groove structure 31b shown in FIG. 14, the conductive sheet 30a having a flat surface and relatively low porosity as shown in FIG. 13, and the conductive sheet 30b having a flat surface and relatively high porosity. The conductive sheets can be connected by any conventional method, such as bonding with a bonding material such as solder. The thickness, size, surface shape, and other characteristics of the combined conductive sheets 30, 31, and 32 can be selected appropriately depending on the characteristics desired for the conductive member 10. In this manner, the conductive member 10 shown in FIG. 2 can be obtained.

[0056] In addition, by stacking multiple sheet members with surface structures and then performing the heat treatment step (S50), the formation of the conductive sheet and the formation of the conductive member 10 (joining multiple conductive sheets) may be performed simultaneously.

[0057] (Embodiment 2) <Configurations and effects of electrolysis device and conductive member> Fig. 17 is a cross-sectional schematic diagram of an electrolysis device 200 according to Embodiment 2. Fig. 17 shows an electrolysis cell 210 of the electrolysis device 200. The electrolysis device 200 may include a plurality of electrolysis cells 210. The electrolysis cell 210 of the electrolysis device 200 mainly includes two bipolar plates 201, a diaphragm 202, an oxygen electrode 203, a hydrogen electrode 204, and a support 205. The oxygen electrode 203 and the hydrogen electrode 204 are arranged so as to sandwich the diaphragm 202. The two bipolar plates 201 are arranged so as to sandwich the oxygen electrode 203 and the hydrogen electrode 204.

[0058] The oxygen electrode 203 and the hydrogen electrode 204 are supported by supports 205. A pipe 207 is installed in a bottom 206 located below the oxygen electrode 203 and the hydrogen electrode 204. The pipe 207 supplies a solution (for example, alkaline water such as a KOH aqueous solution) as an electrolyte to the electrolysis device 200. When power is supplied to the oxygen electrode 203 and the hydrogen electrode 204, the solution is electrolyzed. As a result, oxygen is generated from the oxygen electrode 203 side as shown by arrow 208, and hydrogen is generated from the hydrogen electrode 204 side as shown by arrow 209. In the electrolysis device 200 shown in FIG. 17 , a conductive member 10 is used as the oxygen electrode 203.

[0059] The oxygen electrode 203 serving as the conductive member 10 is a laminate formed by laminating a porous layer 203a and a support layer 203b. A plurality of holes are formed dispersedly in the porous layer 203a serving as the first layer 1. The porous layer 203a has through-holes extending from the surface on the diaphragm 202 side to the surface on the support layer 203b side. The configuration of the porous layer 203a is similar to the configuration of the first layer 1 of the conductive member 10 in the first embodiment shown in FIGS. 3 to 5. That is, similar to the first layer 1 shown in FIGS. 3 to 5, the porous layer 203a also has a plurality of first holes 1a (see FIG. 3), a plurality of second holes 1b (see FIG. 4), and a plurality of third holes 1c (see FIG. 5) formed therein.

[0060] The support layer 203b serving as the second layer 2 is laminated and fixed to the porous layer 203a serving as the first layer 1. The porosity of the support layer 203b serving as the second layer 2 is lower than the porosity of the porous layer 203a serving as the first layer 1. The support layer 203b has a plurality of through-holes that reach from one surface to the other surface of the support layer 203b. The through-holes formed in the support layer 203b serve as exhaust paths for oxygen gas generated in the oxygen electrode 203. The porosity of the portion of the support layer 203b where the through-holes are not formed is, for example, 5% or less.

[0061] In this way, the conductive member 10 can be used as the oxygen electrode 203 for the electrolysis device 200. That is, the first layer 1 can be used as the porous layer 203a, which is a porous electrode of the electrolysis device 200, and the second layer 2 can be used as the support layer 203b that supports the porous layer 203a. As a result, the number of parts and the number of manufacturing steps for the electrolysis device 200 can be reduced compared to when a porous electrode and a support are separately provided in the electrolysis device 200 as the oxygen electrode 203. As a result, the manufacturing cost of the electrolysis device 200 can be reduced.

[0062] The hydrogen electrode 204 mainly includes a porous layer 204a and a cushion layer 204c. The porous layer 204a is disposed so as to face the diaphragm 202. The cushion layer 204c is connected to the back surface of the porous layer 204a opposite to the surface facing the diaphragm 202. The porous layer 204a is made of a conductor. The porous layer 204a has a plurality of through-holes formed therein, extending from the surface facing the diaphragm 202 to the surface facing the cushion layer 204c. The porous layer 204a can be made of, for example, a porous metal such as Celmet (registered trademark) or a mesh metal. The conductive member 10 can also be used as the hydrogen electrode 204 for the electrolysis device 200. In this case, the presence of the support layer allows the hydrogen electrode 204 to effectively receive the pressing force from the support column 205 and the cushion layer 204c, which are located on the opposite side of the diaphragm 202 from the diaphragm 202.

[0063] Any elastic material can be used for the cushion layer 204c. For example, a woven fabric mattress, a coil mattress, or a member including a leaf spring structure can be used for the cushion layer 204c. Any configuration can be used for the cushion layer 204c as long as it can apply a pressing force toward the hydrogen electrode 204 from the support 205 located on the opposite side of the diaphragm 202 from the hydrogen electrode 204.

[0064] The material constituting the porous layer 203a as the first layer 1 and the material constituting the support layer 203b as the second layer 2 each contain at least one selected from the group consisting of nickel, cobalt, manganese, iron, copper, chromium, aluminum, zinc, titanium, tin, and alloys thereof. More specifically, with regard to the oxygen electrode 203 as the conductive member 10 used in the electrolysis device 200, the constituent material may contain at least one selected from the group consisting of nickel, nickel-aluminum (Ni-Al) alloy, nickel-zinc (Ni-Zn) alloy, and nickel-cobalt (Ni-Co) alloy, or a mixture of at least two selected from the above group. In this case, when the conductive member 10 is used in the electrolysis device 200, the performance of the electrolysis device 200 can be sufficiently ensured.

[0065] <Modification> FIG. 18 is a cross-sectional schematic diagram of a conductive member 10 constituting a modified example of the electrolytic device 200 shown in FIG. 17. FIG. 18 corresponds to a cross-sectional schematic diagram of the conductive member 10 in the horizontal direction in the electrolytic device 200 of FIG. 17. The electrolytic device including the conductive member 10 shown in FIG. 18 basically has the same configuration as the electrolytic device 200 shown in FIG. 17, but the configuration of the oxygen electrode 203 serving as the conductive member 10 differs from that of the electrolytic device 200 shown in FIG. 17. The conductive member 10 of the electrolytic device shown in FIG. 18 is the oxygen electrode 203, and includes a porous layer 203a serving as the first layer 1 and a support layer 203b serving as the second layer 2. A plurality of through-holes 203ba are formed in the support layer 203b. A plurality of recesses 203aa are formed in the surface of the porous layer 203a serving as the first layer 1, which is exposed from the through-holes 203ba of the support layer 203b serving as the second layer 2. In this case, by forming the recesses 203aa, the surface area of ​​the portion of the porous layer 203a serving as the first layer 1 that faces the through-holes 203ba of the support layer 203b can be made larger than when the recesses 203aa are not formed. Therefore, in addition to the same effects as those of the electrolysis device 200 shown in Fig. 17, when oxygen gas generated by electrolyzing water or the like is discharged to the outside of the oxygen electrode 203 through the through-holes 203ba of the support layer 203b, the oxygen gas can be efficiently discharged to the outside.

[0066] 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 rather than the above-described embodiments, and it is intended to include any modifications within the scope of the claims and meanings equivalent to the claims. [Explanation of symbols]

[0067] 1 first layer, 1a first hole, 1b second hole, 1c third hole, 1d oxide, 1e, 1f, 3e, 3f surface, 1g, 3g, 32g, 203ba through hole, 2 second layer, 3 third layer, 4 groove, 10 conductive member, 20 sheet member, 21a, 21b roll, 30, 30a, 30b, 31, 32 conductive sheet, 31a convex portion, 31b groove structure, 41, 43 flow path, 50 cell structure, 61, 63, 203a, 204a porous layer, 62 partition wall layer, 70 cell, 100 fuel cell, 200 electrolysis device, 201 bipolar plate, 202 diaphragm, 203 oxygen electrode, 203aa recess, 203b support layer, 204 hydrogen electrode, 204c cushion layer, 205 Supports, 206 bottom, 207 piping, 208,209 arrows, 210 electrolytic cell.

Claims

1. a first layer that is a porous body; a second layer laminated on the first layer, the first layer is used in a current collector for a fuel cell or an electrode for an electrolyzer; the porosity of the second layer is lower than the porosity of the first layer; the porosity of the second layer is 5% or less; The second layer has a plurality of through holes.

2. The conductive member according to claim 1 , wherein the first layer has a plurality of recesses on a surface facing the through hole of the second layer.

3. 3. The conductive member according to claim 1, wherein the material constituting the first layer and the material constituting the second layer each include at least one selected from the group consisting of nickel, cobalt, manganese, iron, copper, chromium, aluminum, zinc, titanium, tin, and alloys thereof.

4. The first layer is a plurality of first holes each having a diameter of 1 mm or more; a plurality of second holes each having a diameter of 100 μm or more and less than 1 mm; The conductive member according to claim 1 or 2, further comprising a plurality of third holes each having a diameter of less than 100 μm.

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