Electrode, membrane electrode assembly, electrochemical cell, battery pack, and electrolysis device

Abstract

An electrode according to an embodiment includes a substrate including metal fibers or metal particles and having a first surface and a second surface located on the opposite side of the first surface, and a catalyst layer provided on the first surface side of the substrate of the fibers or metal particles of the substrate. When the average fiber diameter of the metal fibers and the average primary diameter of the metal particles are defined as D and the direction from the first surface of the base material toward the second surface of the base material is defined as the thickness direction of the base material, the catalyst layer is provided at a depth of 3 * D or more and 10 * D or less from the first surface.

Description

[0001] [Citation of relevant applications]

[0002] This application is based on Japanese Patent Application 2024-162629 (filed on September 19, 2024), and enjoys priority benefits from this application. This application incorporates the entire contents of that application by reference. Technical Field

[0003] This invention relates to electrodes, membrane electrode assemblies, electrochemical cells, battery packs, and electrolysis devices. Background Technology

[0004] In recent years, electrochemical batteries have been actively researched. Among electrochemical batteries, solid polymeric membrane electrolysis cells (PEMECs) are expected to be used for hydrogen generation in large-scale energy storage systems. To ensure sufficient durability and electrolysis performance, platinum (Pt) nanoparticle catalysts are typically used at the cathode of PEMECs, while iridium (Ir) nanoparticle catalysts are used at the anode. Additionally, methods for obtaining hydrogen from ammonia have been investigated. Furthermore, it can also be used as the anode in electrolytic devices that electrolyze carbon dioxide to produce methanol, ethylene, and other organic compounds, as well as carbon monoxide. Summary of the Invention

[0005] The implementation methods involve electrodes, membrane electrode assemblies, electrochemical cells, battery packs, and electrolysis devices.

[0006] The electrode in this embodiment includes a substrate and a catalyst layer. The substrate comprises metal fibers or metal particles and has a first surface and a second surface located on the side opposite to the first surface. The catalyst layer is disposed on the first surface side of the substrate containing the fibers or metal particles. The average fiber diameter of the metal fibers and the average primary diameter of the metal particles are defined as D. The direction from the first surface of the substrate to the second surface is defined as the thickness direction of the substrate. The catalyst layer is disposed at a depth of 3×D or more from the first surface and a depth of 10×D or less.

[0007] Based on the above configuration, an electrode with excellent durability can be obtained. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the electrodes in the embodiment.

[0009] Figure 2 This is a schematic cross-sectional view of the catalyst layer in the embodiment.

[0010] Figure 3 This is a partial schematic diagram of the electrodes in the embodiment.

[0011] Figure 4 This is a partial schematic diagram of the electrodes in the embodiment.

[0012] Figure 5 This is a partial schematic diagram of the electrodes in the embodiment.

[0013] Figure 6 This is a partial schematic diagram of the electrodes in the embodiment.

[0014] Figure 7 This is a partial schematic diagram of the electrodes in the embodiment.

[0015] Figure 8 This is a partial schematic diagram of the electrodes in the embodiment.

[0016] Figure 9 This is a partial schematic diagram of the electrodes in the embodiment.

[0017] Figure 10 This is a partial schematic diagram of the electrodes in the embodiment.

[0018] Figure 11 This is the analysis point for the implementation method.

[0019] Figure 12 This is a schematic diagram of the membrane electrode assembly according to the embodiment.

[0020] Figure 13 This is a partial schematic diagram of the membrane electrode assembly according to the embodiment.

[0021] Figure 14 This is a schematic diagram of an electrochemical cell according to an embodiment.

[0022] Figure 15 This is a schematic diagram of the battery pack in the implementation method.

[0023] Figure 16 This is a conceptual diagram of the electrolysis apparatus for an implementation method.

[0024] Figure 17 This is a table of an example.

[0025] Figure 18 This is a table of an example.

[0026] [Explanation of reference numerals in the attached figures]

[0027] 1: Substrate

[0028] 1A: Metal Fiber

[0029] 1B: Metal particles

[0030] 2: Catalyst layer

[0031] 2A: Layer

[0032] 2B: Interstitial layer

[0033] 2C: Columnar body

[0034] 9: Intersection

[0035] 11: First electrode

[0036] 11A: First catalyst layer

[0037] 11B: First substrate

[0038] 12: Second electrode

[0039] 12A: Second catalyst layer

[0040] 12B: Second substrate

[0041] 13: Electrolyte membrane

[0042] 21: Washer

[0043] 22: Washer

[0044] 23: Diaphragm

[0045] 24: Diaphragm

[0046] 31: Fastening plate

[0047] 32: Fastening plate

[0048] 41: Power supply

[0049] 42: Gas-liquid separation device

[0050] 43: Mixing tank

[0051] 44: Ion exchange water production equipment

[0052] 46: Pump

[0053] 47: Check valve

[0054] 48: Gas-liquid separation device

[0055] 49: Hydrogen refining unit

[0056] 50: Valve

[0057] 100: Electrode

[0058] 200: Membrane electrode assembly

[0059] 300: Electrochemical Battery

[0060] 400: Battery pack

[0061] 500: Water Electrolysis System Detailed Implementation

[0062] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0063] In addition, in the following description, the same reference numerals will be used to mark the same parts, and the description of parts that have been described once will be omitted appropriately.

[0064] The physical property values ​​in the instruction manual are those at a temperature of 25°C and a pressure of 1 atom. The thickness of each component is the average of the distances in the stacking direction.

[0065] The thickness and structure of the components described in the instruction manual can be determined by examining cross-sections obtained using images obtained from scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM), etc. Furthermore, the boundaries of the components described in the instruction manual can be determined using images obtained from scanning electron microscopy, transmission electron microscopy, measurements from scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), measurements from transmission electron microscopy with energy dispersive X-ray spectroscopy (TEM-EDX), secondary ion mass spectrometry, etc. Furthermore, the composition of the components described in the specification can be determined using secondary ion mass spectrometry, inductively coupled plasma mass spectrometry (ICP-MS), scanning electron microscopy with energy-dispersive X-ray spectrometry, and transmission electron microscopy with energy-dispersive X-ray spectrometry. Additionally, the crystallinity of the components described in the specification can be evaluated using images obtained from X-ray diffraction (XRD), electron backscatter diffraction (EBSD), or high-angle annular dark-field scanning transmission electron microscopy, scanning electron microscopy, and transmission electron microscopy. The materials contained in the components described in the specification (crystal defects, bonding states, etc.) can be evaluated using high-angle annular dark-field scanning transmission electron microscopy, photoluminescence (PL), and X-ray photoelectron spectroscopy (XPS). These analytical methods are examples and do not negate the specific analytical methods described in the specification.

[0066] (First Implementation)

[0067] The first embodiment relates to electrodes. Figure 1 A schematic cross-sectional view of the electrode 100 according to the embodiment. The electrode 100 has a substrate 1 and a catalyst layer 2. The catalyst layer 2 is disposed on the substrate 1.

[0068] In this embodiment, catalyst layer 2 serves as a catalyst for electrolysis. Electrolysis reactions include, for example, the production of hydrogen from water or ammonia, or the production of ammonia from nitrogen. Electrolysis reactions also include, for example, the production of carbon monoxide from carbon dioxide. Catalyst layer 2 serves as a catalyst for these reactions.

[0069] The electrode 100 of the first embodiment is used, for example, as the anode of water electrolysis. If the catalyst layer 2 also includes a catalyst for a fuel cell, the electrode 100 of the embodiment is also used as the oxygen electrode of a fuel cell. The electrode 100 of the embodiment can also be used as the anode for electrolysis to generate ammonia. The electrode of the embodiment can be used as the anode of an electrolysis apparatus for ammonia synthesis. Hereinafter, water electrolysis will be described as an example in the first embodiment and other embodiments, but in addition to water electrolysis, the electrode 100 of the embodiment can also be used as the anode of a membrane electrode assembly used in the electrolysis for ammonia synthesis. In this electrolysis for ammonia synthesis, for example, ultrapure water and electrolyte are supplied to the anode, where water is decomposed to generate protons and oxygen. Protons that generate the electrolyte membrane pass through, and nitrogen supplied to the cathode combines with protons and electrons to generate ammonia. The electrode 100 of the embodiment can also be used as the cathode for electrolysis of ammonia to generate hydrogen. The electrode of the embodiment can also be used as the cathode of a hydrogen generation apparatus. Hereinafter, in the first embodiment and other embodiments, water electrolysis will be used as an example for description. However, in addition to water electrolysis, the electrode 100 of the embodiment can also be used as the cathode of the membrane electrode assembly used in the electrolysis for ammonia decomposition. The electrolysis for ammonia decomposition involves supplying ammonia to the cathode, decomposing the ammonia at the cathode to generate protons and nitrogen, generating protons of the electrolyte membrane, and combining the protons with electrons at the anode to generate hydrogen.

[0070] The substrate 1 is preferably made of a porous material with high electrical conductivity. The substrate 1 is a porous component that allows gas and liquid to pass through.

[0071] The substrate 1 comprises metal fibers 1A or metal particles 1B. The substrate 1 preferably comprises metal fibers 1A or metal particles 1B of valve metal.

[0072] The substrate 1 containing metal fibers 1A is preferably a fabric containing metal fibers 1A. The metal fibers 1A are preferably laminated (wound) in the thickness direction C of the substrate 1. The fabric containing metal fibers 1A is preferably a web of metal fibers 1A or a nonwoven fabric of metal fibers 1A.

[0073] The substrate 1 containing metal particles 1B is preferably a sintered body formed by the agglomeration of metal particles 1B. The metal particles 1B are preferably stacked in the thickness direction C of the substrate 1.

[0074] The metal fiber 1A preferably contains one or more metals selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, nickel, platinum, tungsten, bismuth and antimony, more preferably titanium that is stable under electrolytic conditions, and even more preferably titanium.

[0075] The fiber diameter of the metal fiber 1A is preferably 1 μm or more and 500 μm or less, and more preferably 1 μm or more and 100 μm or less, considering reactivity and power supply. The average fiber diameter of the metal fiber 1A is preferably 1 μm or more and 500 μm or less, and more preferably 1 μm or more and 100 μm or less, considering reactivity and power supply. A coarser fiber diameter results in a larger surface roughness of the catalyst, reducing the area of ​​the contact interface with the membrane and the catalyst, which is undesirable. Furthermore, a thinner membrane results in lower battery resistance, which is desirable, but it also contributes to the possibility of membrane short circuits, which is also undesirable. On the other hand, a thinner membrane results in water and electrolyte filling the pores, reducing gas diffusion, which is also undesirable.

[0076] Metal particles 1B preferably comprise one or more metals selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, nickel, platinum, tungsten, bismuth and antimony, more preferably titanium, and even more preferably titanium.

[0077] The primary particle size (diameter) of the metal particles 1B is preferably 1 μm or more and 500 μm or less, and more preferably 1 μm or more and 100 μm or less, considering reactivity and power supply. The average primary particle size (average diameter) of the metal particles 1B is preferably 1 μm or more and 500 μm or less, and more preferably 1 μm or more and 100 μm or less, considering reactivity and power supply. In the case of larger diameters, the unevenness of the catalyst surface is large, and the contact interface with the film and the contact interface with the catalyst are reduced, which is not preferred. In addition, the thinner the film, the lower the battery resistance, which is preferred, but this also becomes a cause of isoelectric short circuits in the membrane, which is not preferred. On the other hand, if the film is too thin, water and electrolyte fill the pores, reducing gas diffusion, which is not preferred.

[0078] Considering the movement of matter, the porosity of the substrate 1 should be 30 vol% or more and 70 vol% or less, more preferably 40 vol% or more and 60 vol% or less. If the porosity of the substrate 1 is high, the catalyst layer 2 is likely to form deep enough to not contribute to the electrolytic reaction. Furthermore, water and electrolyte fill the voids, reducing gas diffusion, which is undesirable. Conversely, if the porosity of the substrate 1 is low, the catalyst layer 2 is likely to form in a thin area on the surface of the substrate 1. Additionally, conductivity deteriorates, reducing reaction efficiency, which is also undesirable. Furthermore, it is difficult to maintain the physical structure of the substrate 1, easily leading to cracking, etc., resulting in a lack of structural stability in the product during movement or manufacturing, which is also undesirable.

[0079] The substrate 1 has a first surface A and a second surface B located on the opposite side of the first surface A. The first surface A and the second surface B are the main surfaces of the substrate 1. The first surface A and the second surface B of the substrate 1 are flat surfaces or substantially flat surfaces.

[0080] The direction from the first surface A of the substrate 1 toward the second surface B of the substrate 1 is defined as the thickness direction C of the substrate 1. When the first surface A and / or the second surface B are not flat surfaces, the length of the line segment connecting the average surface of the first surface A to the average surface of the second surface B is defined as the thickness of the substrate 1. Furthermore, when the first surface A and / or the second surface B are not flat surfaces, the direction in which the line segment connecting the average surface of the first surface A to the average surface of the second surface B extends is defined as the thickness direction C.

[0081] A catalyst layer 2 is provided on the first surface A of the substrate 1. The catalyst layer 2 is disposed on the surface of the metal fiber 1A or metal particle 1B of the substrate 1. Preferably, the catalyst layer 2 is disposed directly on the surface of the metal fiber 1A or metal particle 1B of the substrate 1.

[0082] Catalyst layer 2 preferably comprises one or more elements selected from the group consisting of Ir, Ru, Pt, Pd, Ni, Co, Mn, Fe, Cu, V, Au, Cr, Sr, Y, Ag, Sn, W, Zn, Nb, Ta, Zr, Ti, Mo, and Hf. Catalyst layer 2 preferably comprises oxides containing one or more elements selected from the group consisting of Ir, Ru, Pt, Pd, Ni, Co, Mn, Fe, Cu, V, Au, Cr, Sr, Y, Ag, Sn, W, Zn, Nb, Ta, Zr, Ti, Mo, and Hf.

[0083] Catalyst layer 2 preferably contains one or more noble metals selected from the group consisting of Ir, Ru, Pt, and Pd. Catalyst layer 2 preferably contains one or more noble metals selected from the group consisting of Ni, Co, Mn, and Fe, and more preferably contains Ni.

[0084] The catalyst layer 2 is preferably a porous material. The porosity of the catalyst layer 2 is preferably 10% or more and 90% or less, more preferably 30% or more and 70% or less. Below this value, water and electrolyte fill the pores, reducing gas diffusion, which is undesirable. Above this value, conductivity deteriorates, reducing reaction efficiency, which is also undesirable. Furthermore, it is difficult to maintain the physical structure of the substrate 1, easily leading to cracking, peeling, etc., resulting in a lack of structural stability in the product during transport or manufacturing, and is therefore undesirable.

[0085] The amount of noble metal in catalyst layer 2 is preferably 0.01 mg / cm³. 2 ] and above 1.0 [mg / cm 2 ] or less, more preferably 0.05 [mg / cm³] 2 ] and above and 0.5 [mg / cm 2 The following is a summary of the mass. This total mass can be determined by ICP-MS. To minimize the amount of expensive precious metals, it is preferable to use even less within a range that does not significantly impede the reaction.

[0086] The thickness of the catalyst layer 2 is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less.

[0087] The thickness of the catalyst layer 2 is preferably 0.00002% to 10% of the thickness of the substrate 1, more preferably 0.0005% to 0.5%.

[0088] The catalyst layer 2 preferably has a structure in which sheet layers 2A and interstitial layers 2B are alternately stacked. The stacked structure of the catalyst layer 2 is shown in... Figure 2 A schematic cross-sectional view of catalyst layer 2. Lamellar layers 2A and interstitial layers 2B are stacked in approximately parallel. Most of interstitial layer 2B is void, but a portion is formed by laminations 2A extending out and connecting to laminations 2A. Lamellar layers 2A are connected by columnar structures 2C present in interstitial layer 2B, maintaining the stacked structure.

[0089] Layer 2A is a layer composed of unsupported catalysts, such as metal oxides, arranged in a sheet-like form. Some voids also exist within layer 2A. Layer 2A is a dense layer containing a large amount of catalyst.

[0090] Interstitial layer 2B is the region sandwiched between sheets 2A, containing catalyst particles that are unsupported metal oxides. Unlike sheets 2A, interstitial layer 2B does not have a regular structure of the catalyst. Interstitial layer 2B is a region of low catalyst density.

[0091] The average thickness of one layer of sheet 2A is preferably 6 nm or more and 50 nm or less. The average thickness of one layer of interstitial layer 2B is preferably 6 nm or more and 50 nm or less. Preferably, the average thickness of one layer of sheet 2A is thicker than the average thickness of one layer of interstitial layer 2B.

[0092] Reference Figures 3 to 10 A partial schematic diagram of electrode 100 is provided, illustrating the location where the catalyst layer 2 is disposed on the substrate 1. By providing the catalyst layer 2 as in the embodiment, the durability and electrolysis characteristics of electrode 100 are improved.

[0093] When the average fiber diameter of metal fiber 1A and the average primary diameter of metal particle 1B are set as D, the catalyst layer 2 of the electrode 100 in the embodiment is disposed at a depth of 3×D above the first surface A (first starting point) and at a depth of 10×D below the second ending point F.

[0094] exist Figure 3The schematic diagram shows the depths H at position 1XD, G at position 2XD, E at position 3XD, and F at position 10XD of an electrode 100 using a substrate 1 containing metal fibers 1A. The metal fibers 1A partially overlap. Figure 3 The schematic diagram shows the range from the first surface A (first starting point) of the substrate 1 containing metal fiber 1A to a depth of 3×D, position E (first ending point), and the range from the first surface A (first starting point) to a depth of 10×D, position F (second ending point).

[0095] exist Figure 4 The schematic diagram shows the depths H at position 1XD, G at position 2XD, E at position 3XD, and F at position 10XD of an electrode 100 using a substrate 1 containing metal particles 1B. A portion of the metal particles 1B is in direct contact. Figure 4 The schematic diagram shows the range from the first surface A (first starting point) of the substrate 1 containing metal particles 1B to a depth of 3×D, position E (first ending point), and the range from the first surface A (first starting point) to a depth of 10×D, position F (second ending point).

[0096] Preferably, a catalyst layer 2 is also provided on the surface of the substrate 1 that is oriented in a direction other than the thickness direction C.

[0097] The region extending from the first surface A (first starting point) of substrate 1 to a position H (third endpoint) at a depth of 1×D in the thickness direction C of substrate 1 is designated as the first region a. The region extending from the first surface A of substrate 1 to a position H (second starting point) at a depth of 1×D in the thickness direction C of substrate 1 to a position G (fourth endpoint) at a depth of 2×D in the thickness direction C of substrate 1 is designated as the second region b. Preferably, the average thickness of the catalyst layer 2 in the first region a is thicker than the average thickness of the catalyst layer 2 in the second region b. This is because the reaction mainly occurs near the film side of the catalyst layer, so more catalyst is preferred on the side closer to the first surface. This is because, in the depth direction, the reaction is almost complete up to approximately the fourth endpoint, so the catalyst at depths deeper than that contributes less to the reaction.

[0098] The average thickness of the catalyst layer 2 in the second region b is preferably 0.01 times or more and 0.5 times or less than the average thickness of the catalyst layer 2 in the first region a, more preferably 0.05 times or more and 0.4 times or less, and even more preferably 0.1 times or more and 0.3 times or less than the average thickness of the catalyst layer 2 in the first region a.

[0099] The region extending from the first surface A (first starting point) of the substrate 1 to position E (fifth ending point) at a depth of 3×D in the thickness direction C of the substrate 1 is designated as the third region c. When the region extending from the first surface A of the substrate 1 to position E (third starting point) at a depth of 3×D in the thickness direction C of the substrate 1 to position F at a depth of 10×D in the thickness direction C of the substrate 1 is designated as the fourth region d, the average thickness of the catalyst layer 2 in the third region c is preferably thicker than the average thickness of the catalyst layer 2 in the fourth region d.

[0100] The average thickness of the catalyst layer 2 in the fourth region d is preferably 0.001 times or more and 0.2 times or less than the average thickness of the catalyst layer 2 in the third region c, more preferably 0.001 times or more and 0.1 times or less, and even more preferably 0.001 times or more and 0.08 times or less than the average thickness of the catalyst layer 2 in the third region c.

[0101] The area of ​​the metal fiber 1A in the portion where the catalyst layer 2 is provided is preferably the same as or larger than the area of ​​the first surface A (=[longitudinal length of the first surface A]×[transverse length of the first surface A]), more preferably 100% or more and 150% or less of the area of ​​the first surface A, and even more preferably 100% or more and 110% or less.

[0102] The area of ​​the metal particles 1B in the portion where the catalyst layer 2 is provided is preferably the same as or larger than the area of ​​the first surface A (=[longitudinal length of the first surface A]×[lateral length of the first surface A]), more preferably 100% or more and 150% or less of the area of ​​the first surface A, and even more preferably 100% or more and 110% or less.

[0103] like Figure 5 As shown in the partial schematic diagram of electrode 100, catalyst layer 2 is preferably also disposed on the surface of metal fiber 1A along one side of thickness direction C. Catalyst layer 2 faces the side opposite to thickness direction C. According to metal fiber 1A, catalyst layer 2 is also disposed on the surface of the portion of metal fiber 1A not covered in thickness direction C of substrate 1. Since catalyst layer 2 faces the side opposite to thickness direction C, and according to metal fiber 1A, it is disposed not only on the surface of the portion of metal fiber 1A not covered in thickness direction C of substrate 1, but also on the surface of metal fiber 1A along one side of thickness direction C, thereby increasing the area of ​​catalyst layer 2 disposed on it, which helps to improve catalyst utilization efficiency, etc.

[0104] The surface of the metal fiber 1A along the thickness direction C is located within a range of 45° to 135° and 225° to 315° from the center of the circumcircle of the cross-section approximately along the length direction of the metal fiber 1A, at a distance of 45° to 135° and 225° to 315° from the thickness direction C of the substrate 1. The catalyst layer 2 is also preferably provided on the surface of the metal fiber 1A within a range of 45° to 135° and 225° to 315° from the center of the circumcircle of the cross-section approximately along the length direction of the metal fiber 1A, at a distance of 45° to 135° and 225° to 315° from the thickness direction C of the substrate 1. The catalyst layer 2 is also provided on the surface (first surface A side) of the metal particles 1B within a range of greater than 135° and less than 225° from the center of the circumcircle of the cross-section of the metal fiber 1A, at a distance of greater than 135° and less than 225° from the thickness direction C of the substrate 1.

[0105] The catalyst layer 2 disposed on the surface of the metal fiber 1A along the thickness direction C is preferably 30% or more and 90% or less of the total catalyst layer 2, more preferably 40% or more and 85% or less, and even more preferably 50% or more and 80% or less.

[0106] The catalyst layer 2 disposed on the surface of the metal fiber 1A along the thickness direction C also preferably has a structure in which the sheet layer 2A and the interstitial layer 2B are alternately stacked.

[0107] like Figure 6 As shown in the partial schematic diagram of electrode 100, catalyst layer 2 is preferably also provided on the surface of metal particles 1B along one side of the thickness direction C. The catalyst layer 2 faces the side opposite to the thickness direction C, and according to the metal particles 1B, catalyst layer 2 is also provided on the surface of the portion of metal particles 1B not covered in the thickness direction C of the substrate 1. The catalyst layer 2 faces the side opposite to the thickness direction C, and according to the metal particles 1B, it is provided not only on the surface of the portion of metal particles 1B not covered in the thickness direction C of the substrate 1, but also on the surface of metal particles 1B along one side of the thickness direction C, thereby increasing the area of ​​catalyst layer 2 and contributing to improved catalyst utilization efficiency. Furthermore, the cross-section of metal particles 1B can be equivalent to a cross-section perpendicular to the direction along the length of metal fiber 1A.

[0108] The surface of the metal particle 1B along the thickness direction C is within a range of 45° to 135° and 225° to 315° from the center of the circumcircle (dashed line) of the cross-section of the metal particle 1B, extending from the thickness direction C of the substrate 1. Preferably, a catalyst layer 2 is also provided on the surface of the metal particle 1B within a range of 45° to 135° and 225° to 315° from the thickness direction C of the substrate 1, centered on the center of the circumcircle of the cross-section of the metal particle 1B. The catalyst layer 2 is also provided on the surface of the metal particle 1B (first surface A side) within a range of more than 135° and less than 225° from the thickness direction C of the substrate 1, centered on the center of the circumcircle of the cross-section of the metal particle 1B.

[0109] The catalyst layer 2 disposed on the surface of the metal particles 1B along the thickness direction C is preferably 30% or more and 90% or less of the entire catalyst layer 2, more preferably 40% or more and 85% or less, and even more preferably 50% or more and 80% or less.

[0110] The catalyst layer 2 disposed on the surface of the metal particle 1B along the thickness direction C preferably has a structure in which the sheet layer 2A and the interstitial layer 2B are alternately stacked.

[0111] like Figure 7 As shown in the partial schematic diagram of electrode 100, catalyst layer 2 is preferably also disposed on the surface of metal fiber 1A in a direction toward the second surface B side of substrate 1, which is perpendicular to the thickness direction C of substrate 1.

[0112] The surface of the metal fiber 1A facing the second surface B of the substrate 1 in a direction perpendicular to the thickness direction C of the substrate 1 is the back surface of the metal fiber 1A (the surface of the metal fiber 1A in the portion where the polarized light PL irradiated along the thickness direction C is shadowed by the electrode 100 (substrate 1)). Preferably, a catalyst layer 2 is also provided on the surface of the metal fiber 1A in the portion where the polarized light PL irradiated along the thickness direction C is shadowed by the electrode 100 (substrate 1) (the area surrounded by the dashed line).

[0113] The catalyst layer 2, which is also provided on the surface of the metal fiber 1A in the direction that is toward the second surface B side of the substrate 1 compared with the direction perpendicular to the thickness direction C of the substrate 1, is preferably 1 [wt%] or more and 50 [wt%] or less of the entire catalyst layer 2, more preferably 2 [wt%] or more and 40 [wt%] or less, and even more preferably 5 [wt%] or more and 30 [wt%] or less.

[0114] like Figure 8As shown in the partial schematic diagram of electrode 100, catalyst layer 2 is preferably also disposed on the surface of metal particles 1B in a direction toward the second surface B of substrate 1, which is perpendicular to the thickness direction C of substrate 1. Furthermore, the cross-section of metal particles 1B can be equivalent to a cross-section perpendicular to the direction along the length of metal fiber 1A.

[0115] The catalyst layer 2, which is also disposed on the surface of the metal fiber 1A in a direction that is toward the second surface B side of the substrate 1 compared to the direction perpendicular to the thickness direction C of the substrate 1, preferably has a structure in which the sheet layer 2A and the interstitial layer 2B are alternately stacked.

[0116] The surface of the metal particles 1B facing the second surface B of the substrate 1 in a direction perpendicular to the thickness direction C of the substrate 1 is the back surface of the metal particles 1B (the surface of the metal particles 1B in the portion where the polarized light PL irradiated along the thickness direction C is shadowed by the electrode 100 (substrate 1)). Preferably, a catalyst layer 2 is also provided on the surface of the metal particles 1B in the portion where the polarized light PL irradiated along the thickness direction C is shadowed by the electrode 100 (substrate 1) (the area surrounded by the dashed line).

[0117] The catalyst layer 2, which is also disposed on the surface of the metal particles 1B in a direction that is toward the second surface B of the substrate 1 compared to the direction perpendicular to the thickness direction C of the substrate 1, is preferably 1 wt% or more and 50 wt% or less of the entire catalyst layer 2, more preferably 2 wt% or more and 45 wt% or less, and even more preferably 5 wt% or more and 40 wt% or less.

[0118] The catalyst layer 2, which is also disposed on the surface of the metal particles 1B in a direction that is toward the second surface B side of the substrate 1 compared to the direction perpendicular to the thickness direction C of the substrate 1, preferably has a structure in which the sheets 2A and the interstitial layers 2B are alternately stacked.

[0119] like Figure 9 As shown in the partial schematic diagram of the electrode 100, the electrode 100 preferably includes a catalyst layer 2 (the area generally surrounded by double-dotted lines) disposed on the surface of a metal fiber 1A in a direction that faces the second surface B of the substrate 1 in a direction that is perpendicular to the thickness direction C of the substrate 1, and a catalyst layer 2 (the area surrounded by dashed lines) opposite to it in the thickness direction C of the substrate 1.

[0120] The total amount of the catalyst layer 2 disposed on the surface of the metal fiber 1A in the direction perpendicular to the thickness direction C of the substrate 1 toward the second surface B of the substrate 1 and the catalyst layer 2 facing each other in the thickness direction C of the substrate 1 is preferably 3 [wt%] or more and 30 [wt%] or less of the entire catalyst layer 2, more preferably 4 [wt%] or more and 25 [wt%] or less, and even more preferably 5 [wt%] or more and 20 [wt%] or less.

[0121] The catalyst layer 2 disposed on the surface of the metal fiber 1A in a direction toward the second surface B of the substrate 1 compared to the direction perpendicular to the thickness direction C of the substrate 1, and the catalyst layer 2 opposite to it in the thickness direction C of the substrate 1, are preferably arranged in a structure in which sheet layer 2A and interstitial layer 2B are alternately stacked.

[0122] like Figure 10 As shown in the partial schematic diagram of the electrode 100, the electrode 100 preferably includes a catalyst layer 2 (the area generally surrounded by double-dotted lines) disposed on the surface of metal particles 1B in a direction that faces the second surface B of the substrate 1 in a direction perpendicular to the thickness direction C of the substrate 1, and an opposing catalyst layer 2 (the area surrounded by dashed lines) in the thickness direction C of the substrate 1. Furthermore, the cross-section of the metal particles 1B can be equivalent to a cross-section perpendicular to the direction along the length of the metal fiber 1A.

[0123] The total amount of the catalyst layer 2 disposed on the surface of the metal particles 1B in the direction perpendicular to the thickness direction C of the substrate 1 toward the second surface B of the substrate 1 and the catalyst layer 2 facing each other in the thickness direction C of the substrate 1 is preferably 3 [wt%] or more and 40 [wt%] or less of the entire catalyst layer 2, more preferably 4 [wt%] or more and 35 [wt%] or less, and even more preferably 5 [wt%] or more and 30 [wt%] or less.

[0124] The catalyst layer 2 disposed on the surface of the metal particles 1B in a direction toward the second surface B of the substrate 1 compared to the direction perpendicular to the thickness direction C of the substrate 1, and the catalyst layer 2 opposite to the substrate 1 in the thickness direction C, are preferably arranged in a structure of alternating layers of sheet 2A and interstitial layer 2B.

[0125] The location where catalyst layer 2 is located and the ratio of that location can be determined by observing cross-sections at multiple analytical points. For example... Figure 11As shown, with the length D1 and width D2 (D1≥D2) of electrode 100, imaginary lines are drawn from the two opposite sides of electrode 100 in the width direction at a distance D3 (=D1 / 10) inwards, and imaginary lines are drawn from the two opposite sides of electrode 100 in the length direction at a distance D4 (=D2 / 10) inwards. Furthermore, imaginary lines passing through the center of electrode 100 and parallel to the width direction are drawn, and imaginary lines passing through the center of electrode 100 and parallel to the length direction are also drawn. The region centered on the nine points where the imaginary lines intersect is designated as analysis points A1~A9. Each point is square and at least 1 mm in size. 2 The region. Furthermore, the SEM-based observation section relative to... Figure 11 The surface is perpendicular to the direction of width. The thickness of the interstitial layer 2B at analysis points A1 to A9 is determined at 50 nm intervals along the width of the SEM image. The ratio of catalyst layer 2 at specific locations is taken as the average value for each point. The ratio of catalyst layer 2 at specific locations is determined from the volume and ratio of catalyst layer 2. Furthermore, the composition of the substrate 1 and catalyst layer 2 is determined using SEM-EDX analysis.

[0126] Next, an example of a method for fabricating electrode 100 is shown. A sheet precursor, which is essentially a precursor of sheet 2A, and an interstitial layer precursor, which is essentially a precursor of interstitial layer 2B, are alternately sputtered onto a substrate 1. During the formation of the sheet precursor and the interstitial layer precursor, by sputtering at an angle inclined relative to the thickness direction C of the substrate 1 (including both sputtering in the thickness direction C and sputtering at an angle inclined relative to the thickness direction C), a catalyst layer 2 can be formed beyond the portion exposed on the side of the substrate 1 opposite to the thickness direction C. At this time, the sheet precursor and the interstitial layer precursor are formed in an oxidizing atmosphere. The laminate formed by alternating layers of the sheet precursor and the interstitial layer precursor is treated using a solution that selectively dissolves the precursor of interstitial layer 2B. The dissolving solution is, for example, sulfuric acid. After solution treatment, the electrode 100 is obtained by arbitrary heating treatment in an oxidizing atmosphere.

[0127] When forming the sheet precursor and the interstitial layer precursor, the angle of inclination relative to the thickness direction C of the substrate 1 preferably includes an angle of 1° or more and 179° or less in the surface direction relative to the surface of the substrate 1, more preferably an angle of 5° or more and 120° or less, and even more preferably an angle of 10° or more and 90° or less and / or an angle of 90° or more and 170° or less. Furthermore, an angle of 10° or more and less than 90° or / and an angle of greater than 90° and less than 170° is more preferred. If sputtering is performed from a very shallow angle (e.g., 1°), the sputtering efficiency of the catalyst is poor; therefore, a deeper angle is preferred. If sputtering is performed uniformly at all the above angles, it becomes a film formation that moves the target and substrate, making it difficult to apply voltage to the target at a specific angle; therefore, sputtering from an angle containing a shallower angle is preferred. On the other hand, if sputtering is performed only at an angle (90°) that is nearly perpendicular to the surface of the substrate 1, catalysts will not be formed on the side or back of the fibers and metal particles. Therefore, the sputtering angle includes at least 90° in the surface direction relative to the surface of the substrate 1, and preferably includes an angle tilted to a value other than 90°.

[0128] In the embodiment, the electrode 100 has a catalyst layer 2 disposed over a large area on the surface of the substrate 1. As an electrode for electrolysis, the electrode 100 of the embodiment has high durability and high electrolysis performance.

[0129] (Second Implementation)

[0130] The second embodiment relates to a membrane electrode assembly (MEA). Figure 12 This is a schematic diagram illustrating the membrane electrode assembly 200 according to an embodiment. The membrane electrode assembly 200 includes a first electrode 11, a second electrode 12, and an electrolyte membrane 13. Preferably, the first electrode 11 is an anode electrode, and the second electrode 12 is a cathode electrode. The first electrode 11 or the second electrode 12 preferably uses the electrode 100 of the first embodiment. The membrane electrode assembly 200 of this embodiment is preferably used for an electrochemical cell or battery pack that generates hydrogen or oxygen.

[0131] The first electrode 11 has a first substrate 11B and a first catalyst layer 11A. The first catalyst layer 11A is disposed on the first substrate 11B. The first catalyst layer 11A is preferably in direct contact with the electrolyte membrane 13. When the electrode 100 is used as the first electrode 11, the first catalyst layer 11A is catalyst layer 2 and the first substrate 11B is substrate 1.

[0132] The second electrode 12 has a second substrate 12B and a second catalyst layer 12A. The second catalyst layer 12A is disposed on the second substrate 12B. The second catalyst layer 12A is disposed on the electrolyte membrane 13 side. Preferably, the second catalyst layer 12A is in direct contact with the electrolyte membrane 13.

[0133] The second substrate 12B is preferably made of a porous material with high electrical conductivity. The second substrate 12B is a porous component that allows gas and liquid to pass through. The second substrate 12B is, for example, carbon paper or a metal mesh. As a metal mesh, a porous substrate of valve metal is preferred. As a porous substrate of valve metal, a porous substrate comprising one or more metals selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony, or a porous substrate comprising one metal selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony, is preferred. The second substrate 12B has a carbon layer (MPL layer) comprising carbon particles and a hydrophobic resin (PTFE, Nafion, or other fluoropolymers). The carbon layer is, for example, disposed between the carbon paper and the second catalyst layer 12A.

[0134] The second catalyst layer 12A has a catalyst metal. The second catalyst layer 12A consists of catalyst metal particles, preferably without the catalyst metal supported on a carrier. The second catalyst layer 12A is preferably a porous catalyst layer. The catalyst metal is not particularly limited, but may include one or more selected from the group consisting of Pt, Rh, Os, Ir, Pd, and Au. Preferably, it includes one or more selected from the group consisting of such catalyst materials. The catalyst metal is preferably a metal, alloy, or metal oxide. The second catalyst layer 12A is preferably, for example, a catalyst unit consisting of multiple alternating layers of sheet-like catalyst layers and interstitial layers.

[0135] The metal content per unit area of ​​the second catalyst layer 12A is preferably 0.02 mg / cm². 2 ] and above 1.0 [mg / cm 2 ] or less, more preferably 0.05 [mg / cm³] 2 ] and above and 0.5 [mg / cm 2 The following is a summary of the mass. The sum of these masses can be determined by ICP-MS.

[0136] The porosity of the second catalyst layer 12A is preferably 10% or more and 90% or less, more preferably 30% or more and 70% or less.

[0137] The electrolyte membrane 13 is preferably a proton-conducting membrane. The electrolyte membrane 13 is preferably a fluorinated polymer or an aromatic hydrocarbon polymer selected from the group consisting of sulfonic acid groups, sulfonylimide groups, and sulfate groups. The electrolyte membrane 13 is preferably a fluorinated polymer having sulfonic acid groups. Examples of fluorinated polymers having sulfonic acid groups include Nafion (manufactured by DuPont), Flemion (manufactured by Asahi Kasei Corporation), Selemion (manufactured by Asahi Kasei Corporation), Aquivion (manufactured by Solvay Specialty Polymers), or Aciplex (manufactured by Asahi Glass Co., Ltd.). Alternatively, various conductive membranes such as anion exchange membranes and porous membranes may be used instead of the proton-conducting membrane.

[0138] The thickness of the electrolyte membrane 13 can be appropriately determined by taking into account the membrane's permeation characteristics, durability, and other properties. From the viewpoint of strength, solvent resistance, and MEA output characteristics, the thickness of the electrolyte membrane 13 is preferably 20 μm or more and 500 μm or less, more preferably 50 μm or more and 300 μm or less, and even more preferably 80 μm or more and 200 μm or less.

[0139] The membrane electrode assembly 200 preferably does not contain ionomers. The membrane electrode assembly 200 preferably does not contain, for example, ionomers coated on the surface of the electrode side.

[0140] The electrolyte membrane 13 preferably includes a noble metal region on the side of the first electrode 11. The noble metal region contains noble metal particles. The noble metal region is preferably present on the surface of the electrolyte membrane 13. The noble metal region is preferably composed of a single region, but it may also be composed of multiple separate regions.

[0141] The precious metal particles are preferably particles of one or more precious metals selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru. The precious metal particles may contain particles of alloys containing one or more alloys selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru. The precious metal particles are preferably particles of one precious metal selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru. Pt particles are preferred. Re particles are preferred. Rh particles are preferred. Ir particles are preferred. Pd particles are preferred. Ru particles are preferred.

[0142] The noble metal particles facilitate the oxidation of hydrogen produced on the cathode side and passing through the electrolyte membrane 13. The noble metal particles suppress hydrogen leakage. Because the noble metal particles are present on the anode side, it is difficult for hydrogen discharged from the cathode side to be oxidized. The area where the noble metal particles are present can also exist on the electrolyte membrane 13 on the second electrode 12 (cathode) side.

[0143] The average circumscribed circle diameter of the noble metal particles is preferably 0.5 nm or more and 50 nm or less, more preferably 1 nm or more and 10 nm or less, and even more preferably 1 nm or more and 5 nm or less.

[0144] Figure 13 A partial cross-sectional view of the membrane electrode assembly 200 is shown in the figure. Figure 13 The diagram shows a configuration using electrode 100 as the first electrode 11. A portion of the catalyst layer 2 may not be in direct contact with the electrolyte membrane 13. This catalyst layer 2, not in direct contact with the electrolyte membrane 13, exists in a region relatively shallow from the first surface A of the substrate 1. Therefore, due to the presence of water diffused into the substrate 1, this catalyst layer 2, not in direct contact with the electrolyte membrane 13, also contributes to the electrolysis reaction.

[0145] The catalyst layer 2 that does not directly contact the electrolyte membrane 13 is preferably 3% or more and 50% or less of the entire catalyst layer 2, more preferably 5% or more and 40% or less, and even more preferably 5% or more and 30% or less.

[0146] By using the durable and high-performance electrode 100 as the anode of the membrane electrode assembly 200, it is possible to operate with high activity for a long time.

[0147] (Third Implementation)

[0148] The third embodiment relates to an electrochemical battery. Figure 14 This is a cross-sectional view showing the electrochemical cell 300 according to the second embodiment. The electrochemical cell 300 will be described below using water electrolysis as an example, but hydrogen can be produced even by decomposing ammonia or other substances besides water.

[0149] like Figure 14 As shown, the electrochemical cell 300 of Embodiment 2 includes a first electrode (anode) 11, a second electrode (cathode) 12, an electrolyte membrane 13, gaskets 21 and 22, a separator 23, and a separator 24. The sealing material of the first electrode 11 can also be used as gasket 21. The sealing material of the second electrode 12 can also be used as gasket 22.

[0150] Preferably, a membrane electrode assembly 200 is used, which is formed by bonding a first electrode (anode) 11, a second electrode (cathode) 12, and an electrolyte membrane 13. Alternatively, the anode power supply and the diaphragm 23 can be provided separately. Alternatively, the cathode power supply and the diaphragm 24 can be provided separately.

[0151] Figure 14In the electrochemical cell 300, a power source (not shown) is connected to membranes 23 and 24, where a reaction occurs at the first electrode 11 and the second electrode 12. Water, for example, is supplied to the first electrode 11, where it is decomposed into protons, oxygen, and electrons. The electrode support and power source are porous materials that function as flow path plates. The generated and unreacted water is discharged, and the protons and electrons are used in the cathode reaction. The cathode reaction is the reaction of protons with electrons to produce hydrogen. Either or both of the generated hydrogen and oxygen are used, for example, as fuel for a fuel cell.

[0152] (Fourth Implementation)

[0153] The fourth embodiment involves a battery pack. Figure 15 This is a schematic cross-sectional view showing the battery pack 400 according to the fourth embodiment. Figure 15 The battery pack 400 shown in the fourth embodiment is formed by connecting multiple MEAs 200 or electrochemical cells 300 in series. Fastening plates 31 and 32 are installed at both ends of the MEAs and electrochemical cells.

[0154] Since the amount of hydrogen generated in an electrochemical cell 300 consisting of a single MEA200 is small, a large amount of hydrogen can be obtained by constructing a battery pack 400 that connects multiple MEA200s or multiple electrochemical cells 300 in series.

[0155] (Fifth Implementation)

[0156] The fifth embodiment relates to an electrolysis apparatus. Figure 16 This is a conceptual diagram showing the electrolysis apparatus according to the fifth embodiment. The electrolysis apparatus 500 uses an electrochemical cell 300 or a battery pack 400. Figure 16 The electrolysis apparatus is used for water electrolysis. An electrolysis apparatus for water electrolysis will be described. For example, in the case of producing hydrogen from ammonia, an apparatus with a structure using electrode 100 is preferred. Furthermore, the electrode described in the embodiment can also be used in an electrolysis apparatus that electrolyzes carbon dioxide to produce organic compounds such as methanol and ethylene, and carbon monoxide.

[0157] like Figure 16As shown, a battery pack 400 is constructed by stacking single cells in series for water electrolysis. A power supply 41 is installed in the battery pack 400 to apply voltage between the anode and cathode. A gas-liquid separator 42, which separates the generated gas from unreacted water, and a mixing tank 43 are connected to the anode side of the battery pack 400. Liquid is pumped from an ion-exchange water production unit 44 to the mixing tank 43 via a pump 46. The liquid is mixed in the mixing tank 43 and circulated to the anode from the gas-liquid separator 42 through a check valve 47. Oxygen generated at the anode is obtained by passing it through the gas-liquid separator 42. On the cathode side, a hydrogen refining unit 49 is continuously connected to the gas-liquid separator 48 to obtain high-purity hydrogen. Impurities are discharged through a path with a valve 50 connected to the hydrogen refining unit 49. To stably control the operating temperature, the heating of the battery pack and mixing tank, the current density during thermal decomposition, and other parameters can be controlled.

[0158] The present invention will now be described in more detail based on embodiments, but the present invention is not limited to the following embodiments.

[0159] (Example A)

[0160] (Example A-1)

[0161] A catalyst layer was formed on a nonwoven fabric of titanium metal fibers with a porosity of 60% and a thickness of 200 μm. The catalyst layer had a structure of 40 layers of alternating lamellar and interstitial layers. A lamellar precursor containing Ir oxide and an interstitial layer precursor containing Ni oxide were alternately formed by sputtering in an oxidizing atmosphere, with the angle relative to the surface of the substrate ranging from 1° to 179°. The loading density of the noble metal was 0.1 mg / cm³. 2 Then, sulfuric acid is used to selectively dissolve most of the interstitial layer precursor to obtain the electrode of the embodiment. The obtained electrode is used as the anode.

[0162] An electrode was obtained by forming a porous catalyst layer containing Pt on carbon paper as a substrate. The resulting electrode was used as the cathode. The loading density of the noble metal was set to 1 mg / cm³. 2 ].

[0163] A Nafion membrane, serving as an electrolyte membrane, was sandwiched between the obtained anode and cathode and pressed together to obtain a membrane electrode assembly. This membrane electrode assembly was then placed between two membranes with flow paths and sealed with gaskets to obtain an electrochemical cell. For the obtained electrochemical cell, the measurement temperature was 80 °C and the current density was 2 A / cm². 2 The battery underwent 5,000 hours of water electrolysis operation to evaluate its durability and battery voltage.

[0164] (Examples A-2 to A-7, Comparative Examples A-1 to A-7)

[0165] use Figure 17 The substrate with the porosity shown in the table was used to fabricate the anode in the same manner as in Example A-1. Figure 17 In the comparative examples marked with an "X" in the sputtering tilt section of the table, the precursors for the lamellar and interstitial layers were formed by fixing them in a direction of 90° relative to the surface direction of substrate 1. Electrochemical cells were fabricated in the same manner as in Example A-1, and the cell voltages were evaluated 30 hours and 5000 hours after the start of water electrolysis operation. The porosity, sputtering tilt, cell voltages 30 hours and 5000 hours after the start of water electrolysis operation, and comparative examples of the examples are summarized in the table below. Figure 17 In the table.

[0166] like Figure 17 As shown in the table, the single cells using the electrodes of the embodiments exhibit good battery voltages and high performance after 30 hours of operation. For the comparative examples where the catalyst layer was not formed by oblique sputtering, the battery voltage was low after 30 hours when the porosity was between 30% and 70%. After 5000 hours of operation, the rate of voltage rise was suppressed to a lower level when using the electrodes of the embodiments. However, when using the electrodes of the comparative examples, even though the battery voltage was sufficiently low after 1 hour of operation, the rate of voltage rise or the battery voltage after 5000 hours of operation was higher than that of the embodiments. It is evident that the electrodes of the embodiments exhibit high durability and high electrolysis performance.

[0167] And, although in Figure 17 The anodes of the embodiments are not shown in the table, but the anodes of the embodiments are different from those of the comparative examples, and are as follows. Figure 5 , Figure 7 and Figure 9 The schematic diagram shows that a catalyst layer is formed not only on the surface side of the titanium fiber, but also on the side surface of a portion of the titanium fiber or the bottom surface of a portion of the titanium fiber in the region on the first side of the substrate.

[0168] (Example B)

[0169] (Example B-1)

[0170] A catalyst layer was formed on a sintered body of titanium metal particles with a porosity of 40% and a thickness of 200 μm. The catalyst layer had a structure of 40 layers of alternating lamellar and interstitial layers. A lamellar precursor containing Ir oxide and an interstitial precursor containing Ni oxide were alternately formed by sputtering in an oxidizing atmosphere, with the angle varying from 0° to 178° relative to the thickness direction of the substrate. The loading density of the noble metal was 0.05 mg / cm³. 2 Then, sulfuric acid is used to selectively dissolve most of the interstitial layer precursor to obtain the electrode of the embodiment. The obtained electrode is used as the anode.

[0171] Using the obtained electrodes, an electrochemical cell was fabricated in the same manner as in Example A, and water electrolysis was performed to evaluate its characteristics.

[0172] (Examples B-2 to B-5, Comparative Examples B-1 to B-5)

[0173] use Figure 18 The substrate with the porosity shown in the table was used to fabricate the anode in the same manner as in Example B-1. Figure 18 In the comparative examples marked with an "X" in the sputtering tilt section of the table, the precursors for the lamellar and interstitial layers were formed by fixing them in a direction of 90° relative to the thickness direction of the substrate 1. Electrochemical cells were fabricated in the same manner as in Example B-1, and the cell voltages were evaluated 1 hour and 5000 hours after the start of water electrolysis operation. The porosity, sputtering tilt, cell voltages 1 hour and 5000 hours after the start of water electrolysis operation, and comparative examples of the examples are summarized in the table below. Figure 18 In the table.

[0174] like Figure 18 As shown in the table, the electrochemical cells using the electrodes of the examples exhibit good battery voltages and high performance from the start of operation for one hour. For the comparative examples, where the catalyst layer was not formed by oblique sputtering, the battery voltage was low after one hour when the porosity was between 30% and 70%. After 5000 hours of operation, the rate of voltage rise was suppressed to a low level when using the electrodes of the examples. However, when using the electrodes of the comparative examples, even though the battery voltage was sufficiently low after one hour of operation, the rate of voltage rise or the battery voltage after 5000 hours of operation was higher than that of the examples. It is evident that the electrodes used in the examples all possess high durability and high electrolysis performance.

[0175] In addition, although Figure 18 The anodes of the embodiments are not shown in the table, but the anodes of the embodiments are different from those of the comparative examples, and are as follows. Figure 6 , Figure 8 and Figure 10 As shown in the schematic diagram, a catalyst layer is formed not only on the surface of the titanium particles, but also on the first side of the substrate, on the side surface of some titanium particles, and on the bottom surface of some titanium particles.

[0176] The electrode 100 of the embodiment exhibits improved durability and performance compared to the electrode of the comparative example, even with the same amount of catalyst layer 2 formed. Therefore, high performance can be maintained without increasing the amount of catalyst, thus reducing the amount of target used during sputtering, which is also preferable from an economic point of view. Since a large amount of catalyst layer 2 exists on the electrolyte membrane 13 side, and a small amount of catalyst layer 2 exists slightly away from the electrolyte membrane 13, it is considered possible to balance durability and high electrolysis performance.

[0177] As an example, water electrolysis has been described, but when electrolysis other than water electrolysis is performed using the electrode 100 of the embodiment, the durability and activity of the electrode 100 are also improved.

[0178] In the specification, some elements are represented only by element symbols.

[0179] The technical solutions for the implementation methods are described below.

[0180] Technical Solution 1

[0181] An electrode having:

[0182] A substrate comprising metal fibers or metal particles, and having a first side and a second side located on the side opposite to the first side; and

[0183] A catalyst layer is disposed on the first surface side of the substrate, which is composed of fibers or metal particles.

[0184] Let D be the average fiber diameter of the metal fiber and the average primary diameter of the metal particle.

[0185] The direction from the first surface of the substrate toward the second surface of the substrate is defined as the thickness direction of the substrate.

[0186] The catalyst layer is disposed at a depth of 3×D or more and a depth of 10×D or less from the first surface.

[0187] Technical Solution 2

[0188] According to the electrode described in technical solution 1, wherein,

[0189] The average fiber diameter of the metal fiber is greater than 1 μm and less than 500 μm.

[0190] The average primary diameter of the metal particles is greater than 1 μm and less than 500 μm.

[0191] Technical Solution 3

[0192] The electrode according to technical solution 1 or 2, wherein,

[0193] The substrate is a cloth containing the metal fibers or a sintered body containing the metal particles.

[0194] Technical Solution 4

[0195] The electrode according to any one of technical solutions 1 to 3, wherein,

[0196] The metal fibers contain titanium.

[0197] The metal particles contain titanium.

[0198] Technical Solution 5

[0199] The electrode according to any one of technical solutions 1 to 4, wherein,

[0200] The region extending from the first surface of the substrate to a depth of 1×D in the thickness direction of the substrate is defined as the first region.

[0201] The region extending from a depth of 1×D from the first surface of the substrate in the thickness direction to a depth of 2×D in the direction towards the second surface is defined as the second region.

[0202] The average thickness of the catalyst layer in the first region is greater than the average thickness of the catalyst layer in the second region.

[0203] Technical Solution 6

[0204] The electrode according to any one of technical solutions 1 to 5, wherein,

[0205] The region extending from the first surface of the substrate to a depth of 1×D in the thickness direction of the substrate is defined as the first region.

[0206] The region extending from a depth of 1×D on the thickness direction of the substrate to a depth of 2×D on the thickness direction of the substrate is defined as the second region.

[0207] The average thickness of the catalyst layer in the second region is more than 0.01 times and less than 0.5 times the average thickness of the catalyst layer in the first region.

[0208] Technical Solution 7

[0209] The electrode according to any one of technical solutions 1 to 6, wherein,

[0210] The region extending from the first surface of the substrate to a depth of 3×D in the thickness direction of the substrate is designated as the third region.

[0211] The region extending from a depth of 3×D from the first surface of the substrate in the thickness direction to 10×D in the thickness direction of the substrate is designated as the fourth region.

[0212] The average thickness of the catalyst layer in the fourth region is more than 0.001 times and less than 0.2 times the average thickness of the catalyst layer in the third region.

[0213] Technical Solution 8

[0214] The electrode according to any one of technical solutions 1 to 7, wherein,

[0215] In a substrate containing the metal fibers, the metal fibers are intertwined and stacked in the thickness direction of the substrate.

[0216] In a substrate containing the metal particles, the metal particles are aggregated and stacked in the thickness direction of the substrate.

[0217] Technical Solution 9

[0218] The electrode according to any one of technical solutions 1 to 8, wherein,

[0219] The catalyst layer is also disposed on the surface of the metal fiber on one side along the thickness direction.

[0220] The catalyst layer is also disposed on the surface of the metal particles on one side along the thickness direction.

[0221] Technical Solution 10

[0222] The electrode according to any one of technical solutions 1 to 9, wherein,

[0223] The catalyst layer is disposed on the surface of the metal fiber, and the surface of the metal fiber faces the second surface of the substrate, compared to the direction perpendicular to the thickness direction of the substrate.

[0224] The catalyst layer is disposed on the surface of the metal particles, and the surface of the metal particles faces the second surface of the substrate, compared to the direction perpendicular to the thickness direction of the substrate.

[0225] Technical Solution 11

[0226] The electrode according to any one of technical solutions 1 to 10, wherein,

[0227] The catalyst layer is disposed on the surface of the metal fibers in a direction that faces the second surface of the substrate relative to the direction perpendicular to the thickness direction of the substrate.

[0228] The catalyst layer disposed on the surface of the metal fiber in a direction toward the second surface side of the substrate, compared to the direction perpendicular to the thickness direction of the substrate, is 3 [wt%] or more and 30 [wt%] or less of the total catalyst layer.

[0229] The catalyst layer is disposed on the surface of the metal particles in a direction that faces the second surface of the substrate relative to the direction perpendicular to the thickness direction of the substrate.

[0230] The catalyst layer disposed on the surface of the metal particles in a direction toward the second surface side of the substrate, compared to the direction perpendicular to the thickness direction of the substrate, is 3 [wt%] or more and 40 [wt%] or less of the total catalyst layer.

[0231] Technical Solution 12

[0232] The electrode according to any one of technical solutions 1 to 11, wherein,

[0233] The porosity of the substrate is above 30% and below 70%.

[0234] Technical Solution 13

[0235] The electrode according to any one of technical solutions 1 to 12, wherein,

[0236] The porosity of the substrate is above 40% and below 60%.

[0237] Technical Solution 14

[0238] The electrode according to any one of technical solutions 1 to 13, wherein,

[0239] The catalyst layer has a structure in which lamellar and interstitial layers are stacked alternately.

[0240] Technical Solution 15

[0241] A membrane electrode assembly comprising:

[0242] The electrode as described in any one of technical solutions 1 to 14; and

[0243] An electrolyte membrane that is in direct contact with the electrode.

[0244] Technical Solution 16

[0245] According to the membrane electrode assembly described in technical solution 15, wherein...

[0246] This includes the catalyst layer that is not in contact with the membrane electrode assembly.

[0247] Technical Solution 17

[0248] An electrochemical battery comprising the membrane electrode assembly described in technical solution 15.

[0249] Technical Solution 18

[0250] A battery pack comprising multiple electrochemical cells as described in technical solution 17.

[0251] Technical Solution 19

[0252] An electrolysis system comprising the battery pack described in technical solution 18.

[0253] The embodiments of the present invention have been described above, but the present invention is not directly interpreted as the above embodiments. During implementation, the constituent elements can be modified and embodied by variation without departing from its spirit. Furthermore, various inventions can be formed by appropriate combinations of the multiple constituent elements disclosed in the above embodiments. For example, constituent elements of different embodiments can be appropriately combined as in the variations.

Claims

1. An electrode comprising: A substrate comprising metal fibers or metal particles, and having a first side and a second side located on the side opposite to the first side; and A catalyst layer is disposed on the first surface side of the substrate, which is composed of fibers or metal particles. Let D be the average fiber diameter of the metal fiber and the average primary diameter of the metal particle. The direction from the first surface of the substrate toward the second surface of the substrate is defined as the thickness direction of the substrate. The catalyst layer is disposed at a depth of 3×D or more and a depth of 10×D or less from the first surface.

2. The electrode according to claim 1, wherein, The average fiber diameter of the metal fiber is greater than 1 μm and less than 500 μm. The average primary diameter of the metal particles is greater than 1 μm and less than 500 μm.

3. The electrode according to claim 1, wherein, The substrate is a cloth containing the metal fibers or a sintered body containing the metal particles.

4. The electrode according to claim 1, wherein, The metal fibers contain titanium. The metal particles contain titanium.

5. The electrode according to claim 1, wherein, The region extending from the first surface of the substrate to a depth of 1×D in the thickness direction of the substrate is defined as the first region. The region extending from a depth of 1×D from the first surface of the substrate in the thickness direction to a depth of 2×D in the direction towards the second surface is defined as the second region. The average thickness of the catalyst layer in the first region is greater than the average thickness of the catalyst layer in the second region.

6. The electrode according to claim 1, wherein, The region extending from the first surface of the substrate to a depth of 1×D in the thickness direction of the substrate is defined as the first region. The region extending from a depth of 1×D on the thickness direction of the substrate to a depth of 2×D on the thickness direction of the substrate is defined as the second region. The average thickness of the catalyst layer in the second region is more than 0.01 times and less than 0.5 times the average thickness of the catalyst layer in the first region.

7. The electrode according to claim 1, wherein, The region extending from the first surface of the substrate to a depth of 3×D in the thickness direction of the substrate is designated as the third region. The region extending from a depth of 3×D from the first surface of the substrate in the thickness direction to 10×D in the thickness direction of the substrate is designated as the fourth region. The average thickness of the catalyst layer in the fourth region is more than 0.001 times and less than 0.2 times the average thickness of the catalyst layer in the third region.

8. The electrode according to claim 1, wherein, In a substrate containing the metal fibers, the metal fibers are intertwined and stacked in the thickness direction of the substrate. In a substrate containing the metal particles, the metal particles are aggregated and stacked in the thickness direction of the substrate.

9. The electrode according to claim 1, wherein, The catalyst layer is also disposed on the surface of the metal fiber on one side along the thickness direction. The catalyst layer is also disposed on the surface of the metal particles on one side along the thickness direction.

10. The electrode according to claim 1, wherein, The catalyst layer is disposed on the surface of the metal fiber, and the surface of the metal fiber faces the second surface of the substrate, compared to the direction perpendicular to the thickness direction of the substrate. The catalyst layer is disposed on the surface of the metal particles, and the surface of the metal particles faces the second surface of the substrate, compared to the direction perpendicular to the thickness direction of the substrate.

11. The electrode according to claim 1, wherein, The catalyst layer is disposed on the surface of the metal fibers in a direction that faces the second surface of the substrate relative to the direction perpendicular to the thickness direction of the substrate. The catalyst layer disposed on the surface of the metal fiber in a direction toward the second surface side of the substrate, compared to the direction perpendicular to the thickness direction of the substrate, is 3 [wt%] or more and 30 [wt%] or less of the total catalyst layer. The catalyst layer is disposed on the surface of the metal particles in a direction that faces the second surface of the substrate relative to the direction perpendicular to the thickness direction of the substrate. The catalyst layer disposed on the surface of the metal particles in a direction toward the second surface side of the substrate, compared to the direction perpendicular to the thickness direction of the substrate, is 3 [wt%] or more and 40 [wt%] or less of the total catalyst layer.

12. The electrode according to claim 1, wherein, The porosity of the substrate is 30 vol% or more and 70 vol% or less.

13. The electrode according to claim 1, wherein, The porosity of the substrate is 40 vol% or more and 60 vol% or less.

14. The electrode according to claim 1, wherein, The catalyst layer has a structure in which lamellar and interstitial layers are stacked alternately.

15. A membrane electrode assembly comprising: The electrode according to any one of claims 1 to 14; and The electrolyte membrane that is in direct contact with the electrode. The membrane electrode assembly includes the catalyst layer that is not in contact with the membrane electrode assembly.

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