Stacked body, membrane electrode assembly, water electrolysis device, and method for manufacturing stacked body

Abstract

The laminate of the present invention comprises a metal porous body on an electrolyte membrane. Metal particles are present on at least the surface and / or within the pores of the metal porous body on the electrolyte membrane side. The average pore size of the metal porous body is preferably 0.5 μm to 100 μm. The average particle size of the metal particles is preferably 5 nm to 200 nm. The thickness of the metal porous body is preferably 1 μm to 500 μm. Preferably, a layer of metal particles is also present between the electrolyte membrane and the metal porous body. The metal porous body is preferably a metal foam or a metal fiber felt.

Description

Technical Field

[0001] This disclosure relates to laminates, membrane electrode assemblies, water electrolysis devices, and methods for manufacturing laminates. Background Technology

[0002] Technologies for storing / transporting renewable energy are gaining attention. As an example, the use of renewable energy to split water to produce hydrogen and oxygen, and the subsequent storage / transportation of this hydrogen, are being considered. Water splitting methods, such as anion exchange membrane electrolysis, can adapt to power fluctuations and utilize materials other than precious metals like stainless steel in the bipolar plates, thus promising a balance between high performance and low cost, and are attracting attention as next-generation technologies.

[0003] Currently, catalysts used for water electrolysis include those with catalyst layers supported on porous supports containing precious metals such as platinum and ruthenium. On the other hand, from the viewpoint of cost reduction, there is a demand for catalysts that do not use precious metals; for example, catalysts using nickel have been investigated. The inventors of this invention have disclosed base metal catalysts suitable for anode electrodes and methods for manufacturing them in Patent Documents 1 and 2.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: US2024 / 0254639 A1

[0007] Patent Document 2: International Publication No. 2022 / 250122 Summary of the Invention

[0008] Catalysts are typically used in combination with electrolyte membranes as membrane electrode junctions. The inventors have obtained insights into how the state of the catalyst-electrolyte membrane interface and its surrounding environment affects catalytic performance.

[0009] The subject of this disclosure is to provide a membrane electrode assembly with higher activity, a laminate suitable for the membrane electrode assembly, and a method for manufacturing the same.

[0010] This disclosure includes the following methods. [1]

[0012] A laminate containing metallic porous structures on an electrolyte membrane.

[0013] Metal particles are present on at least the surface and / or within the pores of the aforementioned metal porous body on the electrolyte membrane side. [2]

[0015] According to the laminated body described in [1], the average pore size of the above-mentioned metal porous body is 0.5 μm to 100 μm. [3]

[0017] According to the laminate described in [1] or [2], the average particle size of the metal particles is 5 nm to 200 nm. [4]

[0019] The laminate according to any one of [1] to [3], wherein the thickness of the above-mentioned porous metal body is 1 μm to 500 μm. [5]

[0021] The laminate according to any one of [1] to [4], wherein a layer of metal microparticles is further provided between the electrolyte membrane and the metal porous body. [6]

[0023] The laminate according to any one of [1] to [5], wherein the above-mentioned metal porous body is metal foam or metal fiber felt. [7]

[0025] The laminate according to any one of [1] to [6], wherein the above-mentioned metal porous body contains NiOOH. [8]

[0027] The laminate according to any one of [1] to [7], wherein the metal particles are fixed to the metal porous body. [9]

[0029] The laminate according to any one of [1] to [8], wherein the metal particles comprise NiOOH.

[10]

[0031] The laminate according to any one of [1] to [9], wherein the above-mentioned metal porous body is a catalyst.

[11]

[0033] The laminate according to any one of [1] to

[10] , wherein the electrolyte membrane is an anion-conducting membrane.

[12]

[0035] A membrane electrode assembly comprising a laminate as described in any one of [1] to

[11] and a cathode disposed on the electrolyte membrane side of the laminate.

[13]

[0037] A water electrolysis device comprising the membrane electrode assembly described in

[12] .

[14]

[0039] A method for manufacturing a laminate, which is the method for manufacturing a laminate according to any one of claims [1] to

[11] , the method comprising:

[0040] The process (I) of attaching metal particles to at least one surface and / or pore of the aforementioned porous metal body; and

[0041] Step (II) involves placing the surface of the aforementioned porous metal body with attached metal particles onto an electrolyte membrane and stacking them.

[15]

[0043] According to the method for manufacturing the laminate described in

[14] , there is a step (III) between the above-mentioned step (I) and the above-mentioned step (II) to catalyze the above-mentioned metal porous body and the above-mentioned metal particles.

[0044] The subject of this disclosure is to provide a membrane electrode assembly with higher activity, a laminate suitable for the membrane electrode assembly, and a method for manufacturing the same. Attached Figure Description

[0045] Figure 1 This is a schematic cross-sectional view representing an example of a laminated body.

[0046] Figure 2 It means Figure 1 An enlarged view of an example from section A.

[0047] Figure 3 It means Figure 1 An enlarged view of an example from section A.

[0048] Figure 4 This is a schematic cross-sectional view showing an example of a membrane electrode assembly.

[0049] Figure 5 This is a schematic cross-sectional view showing an example of a water electrolysis device.

[0050] Figure 6 This is a SEM image of the porous metal body in Example 2.

[0051] Figure 7 This is a graph showing the current and voltage curves of the water electrolysis apparatus of Comparative Example 1 and Examples 1-3.

[0052] Figure 8 This is a graph showing the current-voltage curves of the water electrolysis apparatus in Comparative Example 2 and Examples 4-6. Detailed Implementation

[0053] The laminated body and its manufacturing method, as well as the membrane electrode assembly, of the present invention will be described below based on embodiments. For clarity, the following description and drawings have been appropriately simplified. Furthermore, for illustrative purposes, the scales of the components in the drawings may sometimes differ significantly.

[0054] In addition, unless otherwise specified, the numerical range represented by “~” in this specification refers to the minimum and maximum values ​​before and after “~”, respectively.

[0055] [Layered Body]

[0056] Reference Figure 1 and Figure 2 The laminate of the first embodiment will be described. Figure 1 This is a schematic cross-sectional view illustrating an example of a laminated structure. Figure 2 yes Figure 1 An enlarged view of part A. Figure 1 and Figure 2 The example shown has a laminate 30 with a metal porous body 10 on the electrolyte membrane 5. The electrolyte membrane 5 is in direct contact with the metal porous body 10. Figure 1 In this design, the electrolyte membrane 5 and the metal porous body 10 are shown with the same length and width, but their size relationship is not limited to this; for example, the electrolyte membrane 5 and the metal porous body 10 can also be of different sizes. Furthermore, the laminate 30 has metal particles 16 on the surface and / or within the pores 15 of the metal porous body 10.

[0057] The metal particles 16 need only be disposed at least on the surface of the electrolyte membrane 5 side and / or within the pores 15. From the viewpoint of obtaining a laminate suitable for high-efficiency membrane electrode assembly by preventing accidental blockage of the pores of the metal porous body, the metal particles 16 are preferably disposed within the pores 15. When the metal particles 16 are disposed within the pores 15, the metal particles 16 need only be disposed at least within the pores 15 on the electrolyte membrane side of the metal porous body 10. Alternatively, the metal particles 16 may also be disposed entirely within the pores 15 of the metal porous body 10. Here, "pores on the electrolyte membrane side" refers to pores formed within a depth of 100 nm from the electrolyte membrane side interface of the metal porous body.

[0058] The metal particles 16 can be loaded onto the surface of the porous metal body 10 or fixed thereon. Alternatively, they can exist in both loaded and fixed states. Here, "loaded" refers to a state where the surface of the porous metal body 10 and the metal particles 16 are only in contact, without any bonding force between them. On the other hand, "fixed" refers to a state in which mechanical bonding force (such as anchoring effects like interlocking and embedding) or chemical bonding force is generated between the surface of the porous metal body 10 and the metal particles 16. Whether the surface of the porous metal body 10 and the metal particles 16 are fixed can be confirmed by observation, for example, by transmission electron microscopy.

[0059] In addition, such as Figure 2As shown in section B, other metal particles 16 can also be further stacked on the metal particles 16 loaded on the surface of the metal porous body 10. In this case, stacking can be performed by loading or by fixation.

[0060] The metal porous body 10 can be made of a single metallic element, an alloy, or a metal oxide. Specific examples of materials for the metal porous body include platinum, cobalt, nickel, palladium, iron, silver, gold, copper, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, and alloys containing these metals, metal compounds containing the aforementioned metals, metal oxides, and combinations thereof. From a manufacturing cost perspective, the metal porous body preferably contains nickel. Furthermore, from the viewpoint of obtaining a laminate suitable for a high-efficiency membrane electrode assembly, the metal porous body 10 preferably possesses catalytic capability. From the viewpoint of improving catalytic capability, the metal porous body preferably contains NiOOH. For example, a layer containing NiOOH can be formed on the surface of the metal porous body by a method described later.

[0061] The shape of the metal porous body 10 only needs to have pores capable of supporting metal particles 16. Examples include metal particle bonds formed by fusing metal particles, foams of the aforementioned metals, felt-like (non-woven fabric, fiber felt) bodies formed from linear or fibrous metals, and mesh-like porous bodies. When the metal porous body is a metal non-woven fabric or metal fiber felt, there are gaps between the linear or fibrous metals.

[0062] In any case of metal particle binders and porous bodies, the pores may or may not be interconnected pore structures. When using the laminate of the present invention for a membrane electrode assembly, from the viewpoint of further improving the efficiency of the membrane electrode assembly, the pores are preferably interconnected pore structures. That is, the pores preferably open on the surface of the metal porous body, extend toward the interior of the metal porous body, and open at the other end on the surface of the metal porous body. The pores may branch inside the metal porous body. In addition, the pores may intersect with other pores inside the metal porous body. By having interconnected pore structures, for example, when obtaining a membrane electrode assembly by loading or fixing metal particles within the pores of a metal porous body, more reactants can be supplied to the metal particles located within the pores from multiple openings. As a result, the efficiency of the membrane electrode assembly can be further improved. The interconnected pore structure can be confirmed, for example, by observing the metal porous body using a transmission electron microscope.

[0063] From the perspectives of water and gas diffusivity and durability, the metal porous body 10 is preferably a metal foam or a metal fiber felt.

[0064] Regarding the pore size of the pores in the porous metal body 10, from the perspective of water and gas diffusivity and ease of entry of metal particles 16 into the pores, the average pore size is preferably 0.5 μm or more, more preferably 0.8 μm or more, further preferably 1 μm or more, even more preferably 10 μm or more, and even more preferably 13 μm or more. On the other hand, from the perspective of the strength of the porous metal body, the upper limit of the average pore size is preferably 100 μm or less, more preferably 85 μm or less, even more preferably 75 μm or less, even more preferably 20 μm or less, even more preferably 18 μm or less, and particularly preferably 15 μm or less. Here, pore size refers to the pore size of the surface of the porous metal body 10. In addition, regarding the average pore size, the surface of the porous metal body 10 is observed using a scanning electron microscope, at least 30 pores are randomly selected, the longest diameter of each pore is measured, and this is taken as the pore size, and the average value is expressed.

[0065] From the perspective of the strength of the porous metal body and the improvement of the performance of the water electrolysis device using the laminate, the thickness of the porous metal body 10 is preferably 1 μm or more, more preferably 1.5 μm or more, even more preferably 2 μm or more, further preferably 20 μm or more, and even more preferably 30 μm or more. On the other hand, there is no particular upper limit to the thickness of the porous metal body 10, and 500 μm or less is sufficient, preferably 400 μm or less, more preferably 250 μm or less, even more preferably 50 μm or less, even more preferably 45 μm or less, and even more preferably 40 μm or less.

[0066] The thickness of a porous metal is represented by the average of values ​​measured at any five points on the porous metal. Thickness can be measured, for example, using a micrometer.

[0067] The metal particles 16 can be made of elemental metals, alloys, or metal oxides. Specific examples of the materials used for the metal particles include platinum, cobalt, nickel, palladium, iron, silver, gold, copper, titanium, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, and alloys containing them, metal compounds containing the aforementioned metals, metal oxides, and combinations thereof. From a manufacturing cost perspective, the metal particles preferably contain nickel. Furthermore, from the viewpoint of obtaining a laminate suitable for a high-efficiency membrane electrode assembly, the metal particles 16 preferably possess catalytic activity. From the viewpoint of improving catalytic activity, the metal particles preferably contain NiOOH. For example, a layer containing NiOOH can be formed on the surface of the metal particles by a method described later.

[0068] From the viewpoint of effectively distributing metal particles within the pores of the metal porous body 10, the particle size of the metal particles 16, in terms of average pore size, is preferably 200 nm or less, more preferably 150 nm or less, and even more preferably 120 nm or less. On the other hand, the lower limit of the particle size of the metal particles 16 is not particularly limited. From the viewpoint of ease of manufacturing of metal particles, the average particle size is preferably 5 nm or more, more preferably 8 nm or more, and even more preferably 10 nm or more. Here, regarding the average particle size, the metal particles 16 are observed using a scanning electron microscope, at least 30 metal particles 16 are randomly selected, the longest diameter of each particle is measured, and this is taken as the particle size, representing its average value.

[0069] The electrolyte membrane 5 can be selected appropriately according to the composition of the water electrolysis device, and can be either an anion-conducting membrane or a proton-conducting membrane. When the above-mentioned metal porous body 10 is used on the anode side, the electrolyte membrane 5 is preferably an anion-conducting membrane.

[0070] Polymers constituting anion-conducting membranes include those having quaternary ammonium groups and imidazolium groups. From the viewpoint of chemical durability, such as alkali resistance, the polymer is preferably one that does not have ether bonds (-O-), sulfonyl groups (-S(=O)2-), and carbonyl groups (-C(=O)-) on its main chain backbone. Polymers described in Japanese Patent Application Publication Nos. 2021-161472 and 2021-042351 are examples of such polymers. From the viewpoint of further improving the efficiency of the membrane electrode assembly, polymers comprising the structure shown in formula (1) below are preferred.

[0071]

[0072] In equation (1), R is independently -N+(R) 1 The quaternary ammonium group shown in 3A,

[0073] R 1 Each is independently an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and multiple R groups exist. 1 They can connect to form nitrogen-containing ring structures.

[0074] A is a monovalent cation.

[0075] m is an integer from 1 to 18.

[0076] n is an integer greater than or equal to 1.

[0077] The thickness of the electrolyte membrane 5 is preferably within a specified range. Specifically, when the laminate is used in a membrane electrode assembly, from the viewpoint of further improving the efficiency of the membrane electrode assembly, the thickness of the electrolyte membrane 5 can be appropriately adjusted in the range of 1 μm to 100 μm, preferably 2 μm to 80 μm.

[0078] The thickness of an electrolyte membrane is represented by the average of values ​​measured at any five points on the membrane. Thickness can be measured, for example, using a micrometer.

[0079] In the laminate of this embodiment, the amount of metal particles disposed within the metal porous body is preferably within a predetermined range. Specifically, from the viewpoint of obtaining a laminate suitable for a highly active membrane electrode assembly, the amount of metal particles disposed per 1 cm³ is preferably [missing information]. 2 The porous metal mass is 0.5 mg / cm³. 2 The above, more preferably 1.0 mg / cm³ 2 The above is further preferred to be 1.5 mg / cm³. 2 That's all. Furthermore, from the viewpoint of reducing manufacturing costs, the preferred amount of metal particles is per 1 cm³. 2 The porous metal mass has a density of 10.0 mg / cm³. 2 The following is more preferably 8.5 mg / cm³ 2 The following is a further preferred value: 6.5 mg / cm³ 2 the following.

[0080] The amount of metal particles can be determined, for example, by dividing the value obtained by subtracting the mass of the metal porous body before the metal particles were added from the mass of the metal porous body after the metal particles were added by the surface area of ​​the metal porous body.

[0081] The laminate 30 of the first embodiment, by having the above-described configuration, increases the total surface area of ​​the metal porous body and the metal particles. Therefore, for example, when using a membrane electrode assembly using the laminate for water electrolysis, the increased contact area with water promotes the reaction. Furthermore, the metal particles within the pores subdivide the flow path, thereby suppressing the retention of generated gas, thus preventing a decrease in reaction efficiency even during continuous use of the water electrolysis apparatus. Additionally, the metal particles disposed on the surface of the metal porous body suppress direct contact between the metal porous body and the electrolyte membrane; for example, even when force is applied in the planar direction of the laminate, mechanical damage to the electrolyte membrane can be suppressed.

[0082] Next, refer to Figure 3 The laminate of the second embodiment will be described. Figure 1 Same as in the first embodiment, Figure 3 It means Figure 1 An enlarged view of an example from section A. Figure 3The example shown has a metal particle layer 50 between the electrolyte membrane 5 and the metal porous body 10. That is, the electrolyte membrane 5 and the metal porous body 10 are respectively disposed on different sides of the metal particle layer 50. In this embodiment, the laminate is sequentially disposed with an electrolyte membrane 5, a metal particle layer 50, and a metal porous body 10. The electrolyte membrane 5 is in direct contact with the metal particle layer 50, and the metal particle layer 50 is in direct contact with the metal porous body 10. Figure 3 In this diagram, the electrolyte membrane 5, the metal microparticle layer 50, and the metal porous body 10 are represented by the same length, but their size relationship is not limited to this. For example, the electrolyte membrane 5, the metal microparticle layer 50, and the metal porous body 10 can also be of different sizes.

[0083] In this embodiment, the metal particle layer 50 refers to a layer in which a plurality of metal particles 16 are aggregated to form a layer. The metal particles constituting the metal particle layer 50 may be the same metal particles as the metal particles 16 disposed on the surface and / or in the pores 15 of the metal porous body 10.

[0084] The thickness of the metal particle layer 50 is preferably within a specified range. Specifically, from the viewpoint of mass movement and catalyst surface area, the thickness of the metal particle layer is preferably 5 nm to 40 μm, more preferably 10 nm to 20 μm, even more preferably 15 nm to 10 μm, further preferably 15 nm to 500 nm, even more preferably 15 nm to 450 nm, and particularly preferably 15 nm to 400 nm.

[0085] The thickness of the metal microparticle layer is represented by the average of values ​​measured at any five points on the metal microparticle layer. The thickness can be measured, for example, using a micrometer.

[0086] The other components in the second embodiment are the same as those in the first embodiment described above, so the description here is omitted.

[0087] The laminated body of the second embodiment, by having the above-described configuration, increases the total surface area of ​​the metal porous body and the metal particles. Therefore, for example, when using a membrane electrode assembly using the laminated body for water electrolysis, the increased contact area with water promotes the reaction. Furthermore, the flow path is subdivided by the metal particles within the pores, thereby suppressing the retention of generated gas, thus preventing a decrease in reaction efficiency even during continuous use of the water electrolysis device. Additionally, the metal particles and metal particle layers disposed on the surface of the metal porous body can suppress direct contact between the metal porous body and the electrolyte membrane; for example, mechanical damage to the electrolyte membrane can be suppressed even when force is applied in the planar direction of the laminated body.

[0088] In both the first and second embodiments, it is preferred that at least one of the metal porous body and the metal particles be catalyzed. This is because by catalyzing the metal porous body and / or the metal particles (hereinafter also referred to as "metal porous bodies, etc."), a more active membrane electrode assembly can be produced.

[0089] As a catalytically activated metal porous body, a metal porous body having a nickel oxide layer containing NiOOH is preferred, and a metal porous body having a NiFe layer on the nickel oxide layer is even more preferred. It should be noted that the specific method of catalytic activation is described below. Alternatively, a known electrolyte polymer (ionomer) can be used to coat the catalyst surface. On the other hand, in this embodiment, water (solution) moves within the membrane electrode junction body described later and exhibits ionic conductivity; therefore, even without using an electrolyte polymer, the ionic conductivity is excellent.

[0090] [Membrane electrode assembly]

[0091] Reference Figure 4 The membrane electrode assembly is described. Figure 4 This is a schematic cross-sectional view showing an example of a membrane electrode assembly. Figure 4 The membrane electrode assembly 8 shown in the example includes at least a cathode 20, an electrolyte membrane 5, and a porous metal body 10. In this embodiment, the stack of the electrolyte membrane 5 and the porous metal body 10 is the stack 30 described in Embodiment 1 or 2 above. In the membrane electrode assembly 8 of this embodiment, the cathode 20 is disposed on the electrolyte membrane 5 side of the stack 30. The electrolyte membrane 5 is in direct contact with the cathode 20.

[0092] In addition, this membrane electrode assembly 8 may also have other layers such as a gas diffusion layer for use in water electrolysis devices. In this membrane electrode assembly 8, the porous metal body 10 functions as the anode.

[0093] The cathode 20 can be appropriately selected from known cathodes. As an example of the cathode 20, a catalyst layer containing metal particles supported on carbon can be cited.

[0094] The metal particles can be elemental metals, alloys, or metal oxides. Specific examples of the materials used for the metal particles include platinum, cobalt, nickel, palladium, iron, silver, gold, copper, titanium, iridium, molybdenum, rhodium, chromium, tungsten, manganese, ruthenium, and alloys containing them, metal compounds containing the aforementioned metals, metal oxides, and combinations thereof. From the viewpoint of further improving the efficiency of the membrane electrode assembly, the metal particles preferably contain at least one selected from the group consisting of platinum and ruthenium, nickel, cobalt, and manganese.

[0095] The cathode 20 may further have a diffusion layer. Examples of diffusion layers include foamed metal layers such as nickel foam and porous carbon layers such as carbon paper. From the viewpoint of further improving the efficiency of the membrane electrode assembly, a porous carbon layer is preferred. When using a porous carbon layer as the diffusion layer, its thickness can be set to 50 μm or more and 300 μm or less.

[0096] [Water Electrolysis Device]

[0097] Reference Figure 5 Explain the water electrolysis device. Figure 5 This is a schematic cross-sectional view showing an example of a water electrolysis device. Figure 5 The water electrolysis apparatus 1 shown in the example includes: an electrolyte membrane 5, an anode 10 disposed on one side of the electrolyte membrane 5, a cathode 20 disposed on the other side, a power supply 7 connected to the anode 10 and the cathode 20, and a water supply unit (not shown) that supplies water or an alkaline solution to the anode 10. In this embodiment, the anode 10 is the aforementioned porous metal body 10, which functions as an anode catalyst 11 and a first diffusion layer 12. Furthermore, the cathode 20 may have at least a cathode catalyst 21, and may further have a second diffusion layer 22. The membrane electrode assembly 8 includes at least an anode 10 disposed on one side of the electrolyte membrane 5 and a cathode 20 disposed on the other side. Figure 5 In this example, the battery cell 6 is further configured with separators 13 and 23 on the outer sides of the anode 10 and cathode 20, respectively. This water electrolysis apparatus 1 can be a single battery cell 6 or a device composed of multiple stacked battery cells 6. It should be noted that the water supply unit can supply water to at least one of the cathode and anode.

[0098] In the case of an anion exchange membrane type water electrolysis device, for example, when water or an alkaline solution is supplied to the anode 10 side while a voltage is applied to both electrodes, water is also supplied to the cathode electrode side, and the following reaction occurs on the cathode 20 side to produce hydrogen gas.

[0099] 2H2O+2e - →2OH - +H2

[0100] hydroxide ions (OH-) - It moves through the electrolyte membrane 5 to the anode 10. The following reaction occurs in the anode 10 to produce oxygen.

[0101] 2OH - →H₂O + 1 / 2O₂ + 2e -

[0102] The generated hydrogen and oxygen are discharged from the battery cell 6 through gas flow paths 14 and 24 provided in the separators 13 and 23, respectively. The gas flow paths are connected to a storage tank or the like via a gas-liquid separator (not shown), and the hydrogen and oxygen are contained in the storage tank or the like after water is separated by the gas-liquid separator.

[0103] The water supplied in this water electrolysis device can be either pure water or an alkaline solution. By using an alkaline solution, water electrolysis can be performed with higher efficiency compared to using pure water. The solute in the alkaline solution is not particularly limited; for example, it can be potassium hydroxide at concentrations below 1M.

[0104] This water electrolysis device may have separators 13 and 23 on the outside of the anode 10 and cathode 20, respectively. The separators do not need to be made of platinum-coated materials; carbon or stainless steel materials can be appropriately selected. When separators 13 and 23 are conductive, separator 13 can be used as the first main electrode, and separator 23 as the second main electrode. A power supply 7 is connected to these first and second main electrodes to apply voltage to the cathode and anode.

[0105] Separators 13 and 23 may also have gas flow paths 14 and 24. Oxygen generated in anode 10 and hydrogen generated in cathode 20 are discharged through gas flow paths 14 and 24 respectively and contained in storage tanks or the like.

[0106] There are no particular limitations on power source 7; any known DC power source can be appropriately selected. This water electrolysis device has excellent response to input power, so it can be used appropriately even with renewable energy sources such as solar and wind power, which have large fluctuations.

[0107] [Manufacturing method of laminated bodies]

[0108] An embodiment of the method for manufacturing the above-described laminate will be described. It should be noted that the above-described laminate is not limited to being manufactured by the manufacturing method described below; the above-described laminate can be easily manufactured according to the manufacturing method described below.

[0109] The method for manufacturing the laminate according to this embodiment includes at least the following steps: (I) attaching metal particles to at least one surface and / or pores of the aforementioned porous metal body; and (II) depositing the surface of the porous metal body with the attached metal particles onto an electrolyte membrane and laminating it. Other steps may also be included as needed. It should be noted that the distinction between each step is for convenience, and may not be explicitly defined when multiple steps are performed simultaneously or continuously.

[0110] Methods for attaching metal particles to porous metal bodies include, for example, the following methods.

[0111] (Ia) A method of immersing a metal porous body in a dispersion of metal particles and removing the dispersion medium, thereby causing the metal particles to adhere to the pores of the metal porous body.

[0112] (Ib) A method of purifying metal particles on the surface of a metal porous body by immersing it in a solution containing metal ions that become metal particles, and by means of chemical reduction.

[0113] (Ic) A method of coating a dispersion of metal particles onto the surface of a metal porous body by a known coating or printing method and drying it, thereby causing the metal particles to adhere to the pores of the metal porous body.

[0114] (Id) A method in which a metal microparticle layer is formed on the surface of an electrolyte membrane by a known coating or printing method, a metal porous body is disposed on the metal microparticle layer, and pressure is applied to cause the metal microparticles to adhere to the pores of the metal porous body. It should be noted that, according to the method described above (Id), steps (I) and (II) are performed simultaneously.

[0115] Metal particles can be loaded or fixed onto the surface of a porous metal body using any of the methods described above (Ia), (Ib), (Ic), and (Id).

[0116] Next, the surface of the aforementioned porous metal body with attached metal particles is placed on the electrolyte membrane and stacked. The electrolyte membrane and the porous metal body may simply overlap, or they may be bonded, pressed together, or fixed using a fixture. Furthermore, the aforementioned anode can be stacked simultaneously to manufacture a membrane electrode assembly, and the aforementioned separators, etc., may also be stacked simultaneously.

[0117] In manufacturing the laminated body according to the second embodiment described above, a layer of metal microparticles is formed on the surface of the electrolyte membrane and / or the metal porous body beforehand, and the electrolyte membrane and the metal porous body are then laminated together. The metal microparticle layer can be formed by coating the surface of the electrolyte membrane and / or the metal porous body with an ink mixture containing metal microparticles and polymers, etc. There are no particular limitations on the method of coating the ink; for example, spraying can be used.

[0118] The metal porous body and / or metal particles are preferably catalyzed. Catalysis can be performed on the metal porous body and the metal particles separately, or it can be performed simultaneously between the above steps (I) and (II).

[0119] The catalytic conversion method is appropriately selected based on the type of metal constituting the metal porous body and / or metal particles. Hereinafter, as an example, a preferred catalytic conversion method is described for cases where the metal porous body and / or metal particles contain nickel.

[0120] As a method for forming a nickel oxide layer containing NiOOH on a nickel-containing porous metal body and / or metal particles, from the viewpoint of maintaining the state of the metal particles adhering to the pores of the porous metal body, a method of oxidizing the surface of the porous metal body and / or metal particles is preferred. As a method of surface oxidation, electrochemical oxidation is preferred.

[0121] Electrochemical oxidation can be exemplified by methods such as preparing a porous metal body with attached metal particles, immersing the porous metal body in an alkaline electrolyte, and applying a voltage to oxidize it. The thickness of the nickel oxide layer can be adjusted by changing the application time of the voltage.

[0122] Next, as needed, a layer containing NiFe is formed on the nickel oxide layer.

[0123] Methods for forming a NiFe-containing layer on a nickel oxide layer include, for example, methods such as aerosol deposition by spraying NiFe particles, and electrodeposition of Fe. From the viewpoint that it is easy to form a NiFe-containing layer within the pores of a porous metal, the electrodeposition of Fe method is preferred.

[0124] Electrodeposition of Fe can be exemplified by impregnating a porous metal body and / or metal particles having the aforementioned nickel oxide layer with Fe. 2+ Methods such as electrodeposition by applying voltage to an electrolyte can be used. By adjusting the application time of the voltage, the thickness of the NiFe-containing layer and the proportion of Fe in the layer can be adjusted.

[0125] Example

[0126] The present invention will be described in more detail below with examples. It should be noted that the present invention is not limited to these descriptions, and appropriate modifications can be made without departing from the spirit of the invention.

[0127] [Examples 1-6 and Comparative Examples 1 and 2]

[0128] A membrane electrode assembly (MEA) having the layer structure shown in Table 1 is manufactured. Figure 6 Images (a) to (d) show SEM images of nickel foam 2 with metallic microparticles on the surface and within the pores, used in Example 2. Figure 6 In (a) to (d), stacked layers of metal microparticles were observed on the surface of a porous metal body with a framework of approximately tens to hundreds of μm.

[0129] [Table 1]

[0130]

[0131] It should be noted that the details of each component in Table 1 are as follows.

[0132] • Ni Foam 1: The surface of the nickel foam (average pore size 35 μm, thickness 200 μm) has a nickel oxide layer containing NiOOH and a layer containing NiFe. The unmodified nickel foam uses material after cleaning / compressing Celmet (registered trademark) Ni-#8 manufactured by Sumitomo Electric Industries, Ltd.

[0133] • Ni Foam 2: This type of nickel foam (average pore size 35 μm, thickness 200 μm) contains nickel microparticles with an average particle size of 50 nm on its surface and within its pores. The nickel foam and nickel microparticles have a nickel oxide layer containing NiOOH and a NiFe layer on their surface. The unmodified nickel foam uses a material obtained by cleaning / compressing Celmet (registered trademark) Ni-#8 manufactured by Sumitomo Electric Industries, Ltd. Ni Foam 2 is formed by spraying an ink mixture containing nickel microparticles and anion exchange polymer onto the unmodified nickel foam.

[0134] • Metal microparticle layer: Nickel microparticles with an average diameter of 50 nm at a concentration of 1 mg / cm³ 2 A layer of metal microparticles (approximately 3 μm thick) is deposited on the anion exchange membrane. The nickel microparticle layer is formed by spraying an ink mixture of nickel microparticles and anion exchange polymer onto the surface of the anion exchange membrane.

[0135] • Ni fiber felt 1: The surface of the nickel fiber felt (nickel fiber sintered body, average pore size 69 μm, thickness 200 μm) has a nickel oxide layer containing NiOOH and a layer containing NiFe. The unmodified nickel fiber felt uses material cleaned from 2NiO6-0.20 manufactured by Bekaert Toko MetalFiber Co., Ltd.

[0136] • Ni fiber felt 2: The nickel fiber felt (sintered nickel fiber body, average pore size 69 μm, thickness 200 μm) has nickel microparticles with an average particle size of 50 nm on its surface and within its pores. The nickel fiber felt and nickel microparticles have a nickel oxide layer containing NiOOH and a layer containing NiFe on their surface. As shown in Table 1, Examples 4-6 have different amounts of nickel microparticles. The unmodified nickel fiber felt used was made from 2NiO6-0.20 manufactured by Bekaert Toko Metal Fiber Co., Ltd., after cleaning.

[0137] • Polymer 1: In the above formula (1), m is 10 and R is a trimethylammonium group polymer. It is the same as polymer IV-C10-TMA obtained in Example 4 of Japanese Patent No. 7432918.

[0138] ·Pt 32.6 Ru 16.9 / C: A catalyst in which PtRu particles are supported on a carbon support in a Pt:Ru ratio of 32.6:16.9 (by weight). TEC66E50 from Tanaka Precious Metals Industry Co., Ltd. was used.

[0139] • Carbon paper: SGL Carbon, SIGRACET GDL 29AA (approximately 190μm thick)

[0140] <Water Electrolysis Experiment>

[0141] The battery cell temperature is 80℃, and a 1M KOH aqueous solution is supplied to the anode side (flow rate 5mL / min). -1 The performance of anion exchange membrane water electrolysis cell units comprising MEAs of Examples 1-6 and Comparative Examples 1 and 2 was evaluated. A charge-discharge apparatus (HJ1010SD8, manufactured by Beidou Electric) was used for cell evaluation. The ionomers contained in the electrolyte membrane and catalyst layer were PFOTFPh-C10. The anion exchange membrane water electrolysis performance of the MEA is shown below. Figure 7 and 8 (Current-voltage curve). The current density is set to 1 A / cm². 2 2A / cm 2 and 4A / cm 2 The required voltage is shown in Table 2. Figure 7 The results of Comparative Example 1 and Examples 1-3 using nickel foam are shown. Figure 8 The results of Comparative Example 2 and Examples 4-6 using nickel fiber felt are shown.

[0142] [Table 2]

[0143]

[0144] In Comparative Example 1 and Examples 1-3 using nickel foam, the MEA of Examples 1-3, which contained nickel microparticles, exhibited lower voltage at the specified current density compared to the MEA of Comparative Example 1, demonstrating higher water electrolysis performance. Figure 7 (and Table 2). Among them, Examples 2 and 3, in which nickel microparticles were introduced into nickel foam and Fe electrodeposition was carried out, showed that higher water electrolysis performance could be obtained.

[0145] The same tendency was also observed in Comparative Example 2 and Examples 4-6, which used nickel fiber felt; the MEAs of Examples 4-6, which contained nickel microparticles, exhibited higher water electrolysis performance than the MEA of Comparative Example 2. Figure 8 (See Table 2). In Example 6, where more nickel microparticles were introduced, higher water electrolysis performance was achieved.

[0146] Industrial availability

[0147] According to this disclosure, a membrane electrode assembly with higher activity, a laminate suitable for the membrane electrode assembly, and a method for manufacturing the same are provided.

Claims

1. A laminate having a metallic porous structure on an electrolyte membrane, Metal particles are present on at least the surface and / or within the pores of the metal porous body on the electrolyte membrane side.

2. The laminated body according to claim 1, wherein, The average pore size of the metal porous body is 0.5μm~100μm.

3. The laminated body according to claim 1, wherein, The average particle size of the metal particles is 5 nm to 200 nm.

4. The laminated body according to claim 1, wherein, The thickness of the porous metal body is 1μm to 500μm.

5. The laminated body according to claim 1, wherein, A layer of metal microparticles is also present between the electrolyte membrane and the metal porous body.

6. The laminate according to claim 1, wherein, The porous metal body is a metal foam or a metal fiber felt.

7. The laminated body according to claim 1, wherein, The porous metal contains NiOOH.

8. The laminated body according to claim 1, wherein, The metal particles are fixed to the metal porous body.

9. The laminate according to claim 1, wherein, The metal particles contain NiOOH.

10. The laminate according to claim 1, wherein, The porous metal is a catalyst.

11. The laminate according to claim 1, wherein, The electrolyte membrane is an anion-conducting membrane.

12. A membrane electrode assembly comprising a laminate according to any one of claims 1 to 11 and a cathode disposed on the electrolyte membrane side of the laminate.

13. A water electrolysis apparatus comprising the membrane electrode assembly as described in claim 12.

14. A method for manufacturing a laminate, which is the method for manufacturing a laminate according to any one of claims 1 to 11, the method comprising: The process (I) of attaching metal particles to at least one surface and / or pore of the porous metal body; and Step (II) involves placing the surface of the metal porous body with attached metal particles onto an electrolyte membrane and stacking them.

15. The method for manufacturing a laminate according to claim 14, wherein, Between step (I) and step (II), there is a step (III) in which the metal porous body and the metal microparticles are catalyzed.

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