Membrane electrode assemblies, electrochemical cells, stacks, electrolyzers

Abstract

To provide a membrane electrode assembly with enhanced durability.SOLUTION: A membrane electrode assembly according to an embodiment has: a first electrode; a second electrode; an electrolyte membrane provided between the first electrode and the second electrode; and a first seal provided in an outer periphery of the first electrode, having a first opening, housing the first electrode in the first opening, and being contact with the electrolyte membrane, or the first seal and a second seal having a second opening, housing the second electrode in the second opening, and being contact with the electrolyte membrane.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a membrane electrode assembly, a bonding method, an electrochemical cell, a stack, and an electrolysis device. [Background technology]

[0002] In recent years, electrochemical cells have been the subject of intensive research. For example, polymer electrolyte membrane electrolysis cells (PEMEC) are expected to be used to generate hydrogen in large-scale energy storage systems. To ensure sufficient durability and electrolytic properties, platinum (Pt) nanoparticle catalysts are generally used in the cathode of PEMEC, and precious metal catalysts such as iridium (Ir) nanoparticle catalysts are generally used in the anode. Methods for obtaining hydrogen from ammonia are also being investigated. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] M. Watanabe et al. J. Electrochem. Soc, 143, No. 12, 3847-3852 (1996) Summary of the Invention [Problem to be solved by the invention]

[0004] The embodiments provide a membrane electrode assembly with low hydrogen leakage. [Means for solving the problem]

[0005] The membrane electrode assembly of the embodiment includes a first electrode, a second electrode, an electrolyte membrane provided between the first electrode and the second electrode, and a first seal provided on the outer periphery of the first electrode, having a first opening, housing the first electrode within the first opening, and in contact with the electrolyte membrane, or a second seal and the first seal, having a second opening, housing the second electrode within the second opening, and in contact with the electrolyte membrane. The first seal includes a first rubber sheet, a first resin sheet, and a second rubber sheet, the first rubber sheet, the first resin sheet, and the second rubber sheet being stacked, and the first resin sheet being positioned between the first rubber sheet and the second rubber sheet. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 2 is a schematic cross-sectional view of a membrane electrode assembly according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram of an electrolyte membrane according to an embodiment. [Figure 3] FIG. 3 is a schematic diagram of a first seal according to the embodiment. [Figure 4] 3A and 3B are schematic diagrams of a first electrode and a second electrode according to the embodiment. [Figure 5] FIG. 4 is a schematic diagram of a second seal according to the embodiment. [Figure 6] FIG. 2 is a schematic cross-sectional view of a membrane electrode assembly according to an embodiment. [Figure 7] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 8] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 9] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 10] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 11] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 12] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 13] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 14] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 15] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 16] 3A to 3C are process diagrams illustrating the membrane electrode assembly according to the embodiment. [Figure 17] 1 is a schematic diagram of an electrochemical cell according to an embodiment. [Figure 18]FIG. 2 is a schematic diagram of a stack according to an embodiment. [Figure 19] 1 is a conceptual diagram of an electrolysis device according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same components will be denoted by the same reference numerals, and the description of components that have already been described will be omitted as appropriate.

[0008] The physical properties in this specification are values ​​at a temperature of 25°C and a pressure of 1 atom. The thickness of each component is the average value of the distance in the stacking direction.

[0009] (First embodiment) The first embodiment relates to a membrane electrode assembly and a method for manufacturing the membrane electrode assembly. FIG. 1 shows a schematic cross-sectional view of a membrane electrode assembly 100 of the embodiment. The membrane electrode assembly 100 has a first electrode 1, a second electrode 2, an electrolyte membrane 3, a first seal 4, and a second seal 5. The first electrode 1 is preferably an anode electrode, and the second electrode 2 is preferably a cathode electrode. The membrane electrode assembly 100 of the embodiment is preferably used in an electrochemical cell or stack that generates hydrogen or oxygen. The members constituting the membrane electrode assembly 100 are stacked, for example, in the Z direction perpendicular to the XY plane. The width direction of the membrane electrode assembly 100 is defined as the X direction. The length direction of the membrane electrode assembly 100 is defined as the Y direction.

[0010] The membrane electrode assembly 100 of the embodiment can also be used for electrolytic generation of ammonia. The membrane electrode assembly 100 of the embodiment can be used as a membrane electrode assembly in an electrolysis device for ammonia synthesis. In the first embodiment and other embodiments below, water electrolysis will be described as an example, but the membrane electrode assembly can also be used as a membrane electrode assembly used in electrolysis for ammonia synthesis, in which ultrapure water is supplied to the anode, the water is decomposed at the anode to generate protons and oxygen, the generated protons pass through the electrolyte membrane, and nitrogen supplied to the cathode is combined with the protons and electrons to generate ammonia. The membrane electrode assembly 100 of the embodiment can also be used as a membrane electrode assembly that electrolyzes ammonia to generate hydrogen. The membrane electrode assembly of the embodiment can be used in a hydrogen generation device. In the following, the first embodiment and other embodiments will be described taking water electrolysis as an example. However, the membrane electrode assembly 100 of the embodiment can also be used as a membrane electrode assembly used for electrolysis for ammonia decomposition, in which ammonia is supplied to a cathode, the ammonia is decomposed at the cathode to generate protons and nitrogen, the generated protons pass through an electrolyte membrane, and the protons and electrons combine at the anode to generate hydrogen.

[0011] The first electrode 1 has a first substrate 1A and a first catalyst layer 1B. The first catalyst layer 1B is provided on the first substrate 1A. The first catalyst layer 1B is provided on the electrolyte membrane 3 side. It is preferable that the first catalyst layer 1B be in direct contact with the electrolyte membrane 3.

[0012] The first substrate 1A is preferably made of a porous, highly conductive material. The first substrate 1A is a porous member that allows gases and liquids to pass through. The first substrate 1A is, for example, carbon paper or a metal mesh. The metal mesh is preferably a porous substrate made of a valve metal. The porous substrate made of a valve metal is preferably a porous substrate containing 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 made of one metal selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony.

[0013] The first catalyst layer 1B contains a catalytic metal. The first catalyst 1B is preferably a catalytic metal particle, and the catalytic metal is not supported on a carrier. The first catalyst 1B is preferably a porous catalytic layer. The catalytic metal is not particularly limited, but preferably contains, for example, one or more selected from the group consisting of Ir, Ru, and Pt. The catalytic metal is preferably a metal, alloy, or metal oxide.

[0014] The amount of metal per area of ​​the first catalyst layer 1B is 0.02 mg / cm 2 ] or more 1.0[mg / cm 2 ] or less, and more preferably 0.05 [mg / cm 2 ] or more 0.5[mg / cm 2 This sum of masses can be measured by ICP-MS.

[0015] The porosity of the first catalyst layer 1B is preferably 10% to 90%, and more preferably 30% to 70%. If the metal content per area of ​​the first catalyst layer 1B is within the above range and the porosity is high, when hydrogen generated at the cathode (second electrode 2) leaks through the electrolyte membrane 3 to the anode (first electrode 1), the first catalyst layer 1B is dense and the hydrogen easily passes through the first catalyst layer 1B and the first substrate 1A. When the leakage prevention measures of the embodiment are implemented, hydrogen leakage can be efficiently suppressed even when a first catalyst layer 1B that is prone to hydrogen leakage due to its high porosity is used. Even when a catalyst layer that is resistant to hydrogen leakage is used for the first catalyst layer 1B, the membrane electrode assembly 100 of the embodiment can effectively suppress hydrogen leakage.

[0016] The second electrode 2 has a second substrate 2A and a second catalyst layer 2B. The second catalyst layer 2B is provided on the second substrate 2A. The second catalyst layer 2B is provided on the electrolyte membrane 3 side. The second catalyst layer 2B is preferably in direct contact with the electrolyte membrane 3.

[0017] The second substrate 2A is preferably made of a porous, highly conductive material. The second substrate 2A is a porous member that allows gases and liquids to pass through. The second substrate 2A is, for example, carbon paper or a metal mesh. The metal mesh is preferably a porous substrate made of a valve metal. The valve metal porous substrate is preferably a porous substrate containing 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 made of one metal selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony.

[0018] The second catalyst layer 2B contains a catalyst metal. The second catalyst layer 2B is preferably made of catalyst metal particles, and the catalyst metal is preferably not supported on a carrier. The first catalyst 1B is preferably a porous catalyst layer. The catalyst metal is not particularly limited, but includes, for example, one or more selected from the group consisting of Pt, Rh, Os, Ir, Pd, and Au. It is preferable that the first catalyst 1B includes one or more selected from the group consisting of such catalyst materials. The catalyst metal is preferably a metal, alloy, or metal oxide.

[0019] The amount of metal per area of ​​the second catalyst layer 2B is 0.02 mg / cm 2 ] or more 1.0[mg / cm 2 ] or less, and more preferably 0.05 [mg / cm 2 ] or more 0.5[mg / cm 2 This sum of masses can be measured by ICP-MS.

[0020] The porosity of the second catalyst layer 2B is preferably 10% or more and 90% or less, and more preferably 30% or more and 70% or less.

[0021] The electrolyte membrane 3 is a proton-conductive membrane. The electrolyte membrane 3 is preferably a fluorine-based polymer or an aromatic hydrocarbon-based polymer having one or more groups selected from the group consisting of a sulfonic acid group, a sulfonimide group, and a sulfate group. The electrolyte membrane 3 is preferably a fluorine-based polymer having a sulfonic acid group. Examples of fluorine-based polymers having a sulfonic acid group that can be used include Nafion (trademark, manufactured by DuPont), Flemion (trademark, manufactured by Asahi Kasei Corporation), Selemion (trademark, manufactured by Asahi Kasei Corporation), Aquivion (trademark; Solvay Specialty Polymers), and Aciplex (trademark, manufactured by Asahi Glass Co., Ltd.).

[0022] The thickness of the electrolyte membrane 3 can be appropriately determined taking into consideration the membrane's properties such as permeability and durability. From the viewpoints of strength, dissolution resistance, and MEA output properties, the thickness of the electrolyte membrane 3 is preferably 20 μm to 500 μm, more preferably 50 μm to 300 μm, and even more preferably 80 μm to 200 μm.

[0023] The electrolyte membrane 3 preferably includes a precious metal region 3A on the first electrode 1 side. The precious metal region 3A includes precious metal particles. The precious metal region 3A is preferably present on the surface of the electrolyte membrane 3. The precious metal region 3A is preferably composed of a single region, but may also be composed of multiple separate regions.

[0024] 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 include particles of an alloy containing one or more precious metals 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. The precious metal particles are preferably Pt particles. The precious metal particles are preferably Re particles. The precious metal particles are preferably Rh particles. The precious metal particles are preferably Ir particles. The precious metal particles are preferably Pd particles. The precious metal particles are preferably Ru particles.

[0025] The precious metal particles oxidize hydrogen generated on the cathode side and passing through the electrolyte membrane 3. The precious metal particles can suppress hydrogen leakage. Because the precious metal particles are present on the anode side, they do not easily oxidize hydrogen discharged from the cathode side. The region where the precious metal particles exist may also be present on the electrolyte membrane 3 on the second electrode 2 (cathode) side.

[0026] The average circumscribing circle diameter of the precious metal particles is preferably 0.5 nm to 50 nm, more preferably 1 nm to 10 nm, and even more preferably 1 nm to 5 nm. The average circumscribing circle diameter of the precious metal particles can be determined by observing a cross section such as that shown in Figure 1 with a SEM (scanning electron microscope) or TEM (transmission electron microscope).

[0027] The first seal 4 is an insulating member provided on the outer periphery of the first electrode 1. The first seal 4 has a first opening 4A. The first electrode 1 is housed within the first opening 4A. The surface of the first seal 4 facing the electrolyte membrane 3 is in contact with the electrolyte membrane 3, preferably in direct contact therewith. The inner surface of the first seal 4 is in contact with the first electrode 1, preferably in direct contact therewith.

[0028] The second seal 5 is an insulating member provided on the outer periphery of the second electrode 2. The second seal 5 has an opening 5A. The second electrode 2 is housed within the opening 5A. The surface of the second seal 5 facing the electrolyte membrane 3 is in contact with the electrolyte membrane 3, preferably in direct contact therewith. The inner surface of the second seal 5 is in contact with the second electrode 2, preferably in direct contact therewith.

[0029] The relationship between the positions of the first electrode 1, second electrode 2, electrolyte membrane 3, first seal 4, and second seal 5 will be described with reference to the schematic diagrams of Figures 2, 3, 4, and 5. Figure 2 shows a schematic top view of the electrolyte membrane 3. Figure 3 shows a schematic top view (a) and a schematic cross-sectional view (b) of the first seal 4. Figure 4 shows a schematic top view (a) and a schematic cross-sectional view (b) of the first electrode 1 and second electrode 2. Figure 5 shows a schematic top view (a) and a schematic cross-sectional view (b) of the second seal 5.

[0030] The following description is based on the assumption that the shape of the components, including the electrolyte membrane 3, is rectangular. In cases where the shapes of the components are different, the relationships between the positions of the first electrode 1, second electrode 2, electrolyte membrane 3, first seal 4, and second seal 5 described in the embodiment can be applied. The width and length can be calculated, for example, from a rectangle circumscribing the components. Taking into account the positions and overlapping relationships of the components shown in Figures 3 to 5, the following relationships of magnitude and difference between the widths and lengths can be applied.

[0031] The width of the electrolyte membrane 3 is W1 and the length is L1. The width of the precious metal region 3A of the electrolyte membrane 3 is W2 and the length of the precious metal region 3A is L2. L1≧W1 is satisfied. L2≧W2 is satisfied.

[0032] The width of the first seal 4 is W0 and the length is L0, where L0≧W0.

[0033] The size and shape of the first seal 4 and the second seal 5 may be the same or different.

[0034] The width of the first electrode 1 is W3 and the length is L3. The sizes and shapes of the first electrode 1 and the second electrode 2 may be the same or different, and L3≧W3 is satisfied.

[0035] When W1-W2 and L1-L2 are 0 (the noble metal region 3A is present over the entire surface of the electrolyte membrane 3 on the first electrode 1 side), the effect of reducing hydrogen leakage is small. W1-W2 is the difference between the width of the electrolyte membrane 3 and the width of the noble metal region 3A. L1-L2 is the difference between the length of the electrolyte membrane 3 and the length of the noble metal region 3A. It is preferable to satisfy W1-W2>0 and L1-L2>0.

[0036] W1-W2 is preferably 0.01 to 0.98 times W1, and more preferably 0.02 to 0.2 times W1. L1-L2 is preferably 0.01 to 0.98 times L1, and more preferably 0.02 to 0.2 times L1. The effect of reducing hydrogen crossover and leakage on the region on the first electrode 1 side where the noble metal region 3A is not present may vary depending on whether the electrolyte membrane 3 is large or small. When W1-W2=1 mm and L1-L2=1 mm, 1 mm is relatively small when the electrolyte membrane 3 is large, but 1 mm may be relatively large when the electrolyte membrane 3 is small.

[0037] It is preferable that W1>W2>W3 and L1>L2>L3 are satisfied. The size of the precious metal region 3A is between the sizes of the electrolyte membrane 3 and the first electrode 1. When this size relationship is satisfied, it is preferable that the first seal 4 is in direct contact with the surface of the electrolyte membrane 3 where the precious metal region 3A is present and the surface of the electrolyte membrane 3 where the precious metal region 3A is not present. By making the precious metal region 3A larger than the first electrode 1, hydrogen leaking through the first electrode 1 can be efficiently oxidized by the precious metal region 3A. If the precious metal region 3A is smaller than the first electrode 1, hydrogen is likely to leak from the first electrode 1 through the electrolyte membrane 3 where the precious metal region 3A is not present.

[0038] The first seal 4 is slippery on the surface of the electrolyte membrane 3 where the precious metal region 3A is present, but is not slippery on the surface of the electrolyte membrane 3 where the precious metal region 3A is not present. When W1>W2>W3 and L1>L2>L3 are satisfied, the first seal 4 is in contact with the surface of the electrolyte membrane 3 where the precious metal region 3A is not present and is not slippery, thereby suppressing expansion and contraction of the electrolyte membrane 3.

[0039] From the viewpoint of preventing both hydrogen leakage and slippage between the first seal 4 and the electrolyte membrane 3, the width W2 of the precious metal region 3A is preferably set between the center of the surface of the electrolyte membrane 3 facing the first electrode 1 and a position that is 0.8 to 1 times W1 in the width direction (W2 / W1 is 0.8 to 1), and the precious metal region 3A is preferably set between the center of the surface of the electrolyte membrane 3 facing the first electrode 1 and a position that is 0.8 to 1 times L1 in the width direction.

[0040] The distance from the center of the surface of the electrolyte membrane 3 facing the first electrode 1 to one end of the precious metal region 3A in the width direction is defined as W5, and the distance to the other end is defined as W6. W5 and W6 are preferably 0.4 to less than 0.5 times W1, and more preferably 0.45 to 0.48 times W1. If W5 and W6 are small, the size of the first opening 4A is small relative to the size of the electrolyte membrane 3, and only a small first electrode 1 can be accommodated in the first seal 4. If W5 and W6 are large, the contact area between the first seal 4 and the electrolyte membrane 3 becomes small.

[0041] The distance from the center of the surface of the electrolyte membrane 3 facing the first electrode 1 in the longitudinal direction to one end of the precious metal region 3A is defined as L5, and the distance to the other end is defined as L6. L5 and L6 are preferably 0.4 to less than 0.5 times L1, and more preferably 0.45 to 0.48 times L1. If L5 and L6 are small, the size of the first opening 4A is small compared to the size of the electrolyte membrane 3, and only a small first electrode 1 can be accommodated in the first seal 4. If L5 and L6 are large, the contact area between the first seal 4 and the electrolyte membrane 3 becomes small.

[0042] It is preferable that W1-W3 is 0.01 to 0.2 times W1, and that L1-L3 is 0.01 to less than 0.2 times L1. W1-W3 and L1-L3 are essentially the width of the first seal 4. If the electrolyte membrane 3 is large, it is preferable that the width of the first seal 4 is somewhat large, but if the electrolyte membrane 3 is small, a narrow width is sufficient. From the above perspective, it is more preferable that W1-W3 is 0.04 to 0.1 times W1, and that L1-L3 is 0.04 to 0.1 times L1.

[0043] If the difference between W5 and W6 and / or the difference between L5 and L6 is large, the surface where the first seal 4 and the electrolyte membrane 3 contact is likely to become uneven. If the surface where the first seal 4 and the electrolyte membrane 3 contact is uneven, the ease of sliding between the first seal 4 and the electrolyte membrane 3 will vary greatly depending on the location. From the above viewpoint, the difference between W5 and W6 (|W5-W6|) is preferably 0.5 to 1.5 times W1, and more preferably 0.8 to 1.2 times W1. From the above viewpoint, the difference between L5 and L6 (|L5-L6|) is preferably 0.5 to 1.5 times L1, and more preferably 0.8 to 1.2 times L1.

[0044] From the viewpoint of preventing expansion and contraction of the electrolyte membrane 3, it is preferable that the width (W7 or W8) where the first seal 4 contacts the precious metal region 3A of the electrolyte membrane 3 is narrower than the width (W9 or W10) where the first seal 4 contacts the region of the electrolyte membrane 3 that is not the precious metal region 3A.

[0045] From the viewpoint of preventing expansion and contraction of the electrolyte membrane 3, it is preferable that the length (L7 or L8) over which the first seal 4 is in contact with the precious metal region 3A of the electrolyte membrane 3 is narrower than the length (L9 or L10) over which the first seal 4 is in contact with the region of the electrolyte membrane 3 that is not the precious metal region 3A.

[0046] The width W1 of the electrolyte membrane 3 and the width W0 of the first seal 4 preferably satisfy W0≧W1. The length L1 of the electrolyte membrane 3 and the length L0 of the first seal 4 preferably satisfy L0≧L1.

[0047] The electrolyte membrane 3 may also have a precious metal region 3B on the second electrode 2 side. In cases such as when the electrolyte membrane 3 has a precious metal region 3B, it is preferable that a second seal 5 is also present on the second electrode 2 side. The membrane electrode assembly 100 in FIG. 1 includes a second seal 5, but the membrane electrode assembly 110 shown in the schematic cross-sectional view of FIG. 6 does not include a second seal 5. The membrane electrode assembly 100 of the embodiment may omit the precious metal region 3B and / or the second seal 5.

[0048] When the electrolyte membrane 3 has a noble metal region 3B, the width of the noble metal region 3B is defined as W12, and the length of the noble metal region 3B is defined as L12, where L12≧W12 is satisfied.

[0049] The width of the second seal 5 is W11, and the length is L11, where L11≧W11.

[0050] The width of the second electrode 2 is W4 and the length is L4, where L4≧W4.

[0051] W1-W12 is preferably 0.01 to 0.98 times W1, and more preferably 0.02 to 0.2 times W1. L1-L12 is preferably 0.01 to 0.98 times L1, and more preferably 0.02 to 0.2 times L1. The effect of reducing hydrogen crossover and leakage on the region on the second electrode 2 side where the noble metal region 3B is not present may vary depending on whether the electrolyte membrane 3 is large or small. When W1-W12=1 mm and L1-L12=1 mm, 1 mm is relatively small when the electrolyte membrane 3 is large, but 1 mm may be relatively large when the electrolyte membrane 3 is small.

[0052] It is preferable that W1 > W12 > W4 and L1 > L12 > L4 are satisfied. The size of the precious metal region 3B is between the sizes of the electrolyte membrane 3 and the second electrode 2. When this size relationship is satisfied, the second seal 5 preferably contacts, and is in direct contact with, the surface of the electrolyte membrane 3 where the precious metal region 3B is present and the surface of the electrolyte membrane 3 where the precious metal region 3B is not present. By making the precious metal region 3B larger than the second electrode 2, hydrogen leaking through the first electrode 1 can be efficiently oxidized by the precious metal region 3B. If the precious metal region 3B is smaller than the second electrode 2, hydrogen may easily leak from the first electrode 1 through the electrolyte membrane 3 where the precious metal region 3B is not present.

[0053] The second seal 5 is slippery on the surface of the electrolyte membrane 3 where the precious metal region 3B is present, but is not slippery on the surface of the electrolyte membrane 3 where the precious metal region 3B is not present. When W1>W12>W4 and L1>L12>L4 are satisfied, the second seal 5 is in contact with the non-slip surface of the electrolyte membrane 3 where the precious metal region 3B is not present, and therefore expansion and contraction of the electrolyte membrane 3 can be suppressed.

[0054] From the viewpoint of preventing both hydrogen leakage and slippage between the second seal 5 and the electrolyte membrane 3, the precious metal region 3B is provided between the center of the surface of the electrolyte membrane 3 facing the second electrode 2 and a position that is 0.8 to 0.99 times W1 in the width direction, and it is preferable that the precious metal region 3B is provided between the center of the surface of the electrolyte membrane 3 facing the second electrode 2 and a position that is 0.8 to 0.99 times L1 in the width direction.

[0055] The distance from the center of the surface of the electrolyte membrane 3 facing the second electrode 2 to one end of the precious metal region 3B in the width direction is defined as W13, and the distance to the other end is defined as W14. W13 and W14 are preferably 0.4 to 0.495 times W1, and more preferably 0.45 to 0.48 times W1. If W13 and W14 are small, the size of the second opening 4B is small relative to the size of the electrolyte membrane 3, and only a small second electrode 2 can be accommodated in the second seal 5. If W13 and W14 are large, the contact area between the second seal 5 and the electrolyte membrane 3 becomes small.

[0056] The distance from the center of the surface of the electrolyte membrane 3 facing the second electrode 2 in the longitudinal direction to one end of the precious metal region 3B is defined as L13, and the distance to the other end is defined as L14. L13 and L14 are preferably 0.4 to 0.495 times L1, and more preferably 0.45 to 0.48 times L1. If L13 and L14 are small, the size of the second opening 4B is small relative to the size of the electrolyte membrane 3, and only a small second electrode 2 can be accommodated in the second seal 5. If L13 and L14 are large, the contact area between the second seal 5 and the electrolyte membrane 3 becomes small.

[0057] It is preferable that W1-W4 is 0.01 to 0.2 times W1, and that L1-L4 is 0.01 to 0.2 times L1. W1-W4 and L1-L4 are essentially the width of the second seal 5. If the electrolyte membrane 3 is large, it is preferable that the width of the second seal 5 is somewhat large, but if the electrolyte membrane 3 is small, a narrow width is sufficient. From the above perspective, it is more preferable that W1-W4 is 0.02 to 0.12 times W1, and that L1-L4 is 0.02 to 0.12 times L1.

[0058] If the difference between W13 and W14 and / or the difference between L13 and L14 is large, the surface where the second seal 5 and the electrolyte membrane 3 contact is likely to become uneven. If the surface where the second seal 5 and the electrolyte membrane 3 contact is uneven, the ease of sliding between the second seal 5 and the electrolyte membrane 3 will vary greatly depending on the location. From the above viewpoint, the difference between W13 and W14 (|W13-W14|) is preferably 0.5 to 1.5 times W1, and more preferably 0.8 to 1.2 times W1. From the above viewpoint, the difference between L13 and L14 (|L13-L14|) is preferably 0.5 to 1.5 times L1, and more preferably 0.8 to 1.2 times L1.

[0059] From the viewpoint of preventing expansion and contraction of the electrolyte membrane 3, it is preferable that the width (W15 or W16) where the second seal 5 contacts the precious metal region 3B of the electrolyte membrane 3 is narrower than the width (W17 or W18) where the second seal 5 contacts the region of the electrolyte membrane 3 that is not the precious metal region 3B.

[0060] From the viewpoint of preventing expansion and contraction of the electrolyte membrane 3, it is preferable that the length (L15 or L16) over which the second seal 5 is in contact with the precious metal region 3B of the electrolyte membrane 3 is narrower than the length (L17 or L18) over which the second seal 5 is in contact with the region of the electrolyte membrane 3 that is not the precious metal region 3B.

[0061] The width W1 of the electrolyte membrane 3 and the width W11 of the second seal 5 preferably satisfy W11≧W1. The length L1 of the electrolyte membrane 3 and the length L11 of the second seal 5 preferably satisfy L11≧L1.

[0062] The first seal 4 includes a first rubber sheet 4B and a first resin sheet 4C. The first seal 4 preferably includes the first rubber sheet 4B, the first resin sheet 4C, and the second rubber sheet 4D. The first resin sheet 4C is located between the first rubber sheet 4B and the second rubber sheet 4D. The first rubber sheet 4B is preferably laminated with the first resin sheet 4C. The first rubber sheet 4B, the first resin sheet 4C, and the second rubber sheet 4D are preferably laminated.

[0063] The thickness of the first seal 4 is, for example, 20 μm or more and 2000 μm or less. The thickness of the first seal 4 is preferably 0.6 times or more and 1.0 times or less the thickness of the first electrode 1.

[0064] An adhesive layer (not shown) may be provided between the first seal 4 and the electrolyte membrane 3 and / or between the first electrode 1 .

[0065] The Young's modulus of the first seal 4 is preferably 0.001 GPa to 5 GPa, and more preferably 0.01 GPa to 3 GPa, within the range of 5°C to 100°C. A high Young's modulus of the first seal 4 can suppress expansion and contraction of the electrolyte membrane 3.

[0066] The first rubber sheet 4B is preferably a sheet of natural rubber or synthetic rubber containing one or more selected from the group consisting of ethylene propylene diene rubber, silicone rubber, nitrile rubber, fluororubber, urethane rubber, acrylic rubber, isopropylene rubber, styrene rubber, butyl rubber, and ethylene propylene rubber. In order to adjust the Young's modulus and linear expansion coefficient of the first rubber sheet 4B, the first rubber sheet 4B may contain one or more selected from the group consisting of carbon fiber, metal mesh, and filler.

[0067] The first resin sheet 4C is an insulating sheet containing one or more materials selected from the group consisting of thermoplastic plastics such as polyethylene terephthalate (PET), polyimide, polypropylene, polyvinyl chloride, etc., and thermosetting plastics such as melamine resin, epoxy resin, etc. In order to adjust the Young's modulus and linear expansion coefficient of the first resin sheet 4C, the first resin sheet 4C may contain one or more materials selected from the group consisting of carbon fiber, metal mesh, and filler.

[0068] The second rubber sheet 4D is preferably a sheet of natural rubber or synthetic rubber containing one or more selected from the group consisting of ethylene propylene diene rubber, silicone rubber, nitrile rubber, fluororubber, urethane rubber, acrylic rubber, isopropylene rubber, styrene rubber, butyl rubber, and ethylene propylene rubber. In order to adjust the Young's modulus and linear expansion coefficient of the second rubber sheet 4D, the second rubber sheet 4D may contain one or more selected from the group consisting of carbon fiber, metal mesh, and filler.

[0069] The second seal 5 includes a third rubber sheet 5B and a second resin sheet 5C. The second seal 5 preferably includes the third rubber sheet 5B, the second resin sheet 5C, and a fourth rubber sheet 5D. The second resin sheet 5C is located between the third rubber sheet 5B and the fourth rubber sheet 5D. The third rubber sheet 5B is preferably laminated with the second resin sheet 5C. The third rubber sheet 5B, the second resin sheet 5C, and the fourth rubber sheet 5D are preferably laminated.

[0070] The thickness of the second seal 5 is, for example, 20 μm or more and 2000 μm or less. The thickness of the second seal 5 is preferably 0.7 times or more and 1 time or less the thickness of the first electrode 1.

[0071] An adhesive layer (not shown) may be provided between the second seal 5 and the electrolyte membrane 3 and / or between the first electrode 1 .

[0072] The Young's modulus of the second seal 5 is preferably 0.01 GPa to 5 GPa, and more preferably 0.01 GPa to 3 GPa, within the range of 5°C to 100°C. A high Young's modulus of the second seal 5 can suppress expansion and contraction of the electrolyte membrane 3.

[0073] The third rubber sheet 5B is preferably a sheet of natural rubber or synthetic rubber containing one or more selected from the group consisting of ethylene propylene diene rubber, silicone rubber, nitrile rubber, fluororubber, urethane rubber, acrylic rubber, isopropylene rubber, styrene rubber, butyl rubber, and ethylene propylene rubber. In order to adjust the Young's modulus and linear expansion coefficient of the third rubber sheet 5B, the third rubber sheet 5B may contain one or more selected from the group consisting of carbon fiber, metal mesh, and filler.

[0074] The second resin sheet 5C is an insulating sheet containing one or more materials selected from the group consisting of thermoplastic plastics such as polyethylene terephthalate (PET), polyimide, polypropylene, polyvinyl chloride, etc., and thermosetting plastics such as melamine resin, epoxy resin, etc. In order to adjust the Young's modulus and linear expansion coefficient of the second resin sheet 5C, the second resin sheet 5C may contain one or more materials selected from the group consisting of carbon fiber, metal mesh, and filler.

[0075] The fourth rubber sheet 5D is preferably a sheet of natural rubber or synthetic rubber containing one or more selected from the group consisting of ethylene propylene diene rubber, silicone rubber, nitrile rubber, fluororubber, urethane rubber, acrylic rubber, isopropylene rubber, styrene rubber, butyl rubber, and ethylene propylene rubber. In order to adjust the Young's modulus and linear expansion coefficient of the fourth rubber sheet 5D, the fourth rubber sheet 5D may contain one or more selected from the group consisting of carbon fiber, metal mesh, and filler.

[0076] A method for manufacturing a membrane electrode assembly 100 will be described with reference to the process schematics of FIGS. 7 to 11. The method for manufacturing a membrane electrode assembly 100 described with reference to the process schematics of FIGS. 7 to 11 relates to a portion of the manufacturing process of the membrane electrode assembly 100. The method for bonding an electrolyte membrane 3 and a first electrode 1 using a first seal 4 includes the following steps: placing an electrolyte membrane 3 (the electrolyte membrane 3 bonded to a second electrode 2 is also referred to simply as the electrolyte membrane 3 in the process of bonding the electrolyte membrane 3 and the second electrode 2) on a first press plate 6, and placing the electrolyte membrane 3 on a second press plate 7, the first seal 4 having a first opening 4A, and the first electrode 1 provided in the first opening 4A face to face; heating the faced components to bond them together; cooling the heated and bonded components; removing the first press plate 6 and the second press plate 7; and optionally peeling off the first seal 4. The steps related to bonding the first seal 4 can be applied to bonding the second seal 5.

[0077] The component 101 shown in the process schematic diagram of FIG. 7 relates to a process of placing an electrolyte membrane 3 provided on a first press plate 6, a first seal 4 provided on a second press plate 7, and a first electrode 1 provided in the first opening 4A facing the first seal 4. The component 101 includes an electrolyte membrane 3 provided on the first press plate 6, and a first electrode 1 provided on the second press plate 7. The first electrode 1 is housed in the first opening 4A of the first seal 4. The electrolyte membrane 3 is placed facing the first seal 4 having the first opening 4A and the first electrode 1 provided in the first opening 4A.

[0078] The member 102 shown in the process schematic diagram of Fig. 8 relates to a process of heating and bonding facing members 101. The member 101 of Fig. 7 is bonded to the electrolyte membrane 3 with the first electrode 1 and the first seal 4 as the member 102 shown in the process schematic diagram of Fig. 8. In bonding, for example, heating is performed at 120°C to 180°C, and a pressure of 10 kg / cm is applied. 2 ] or more 30[kg / cm 2] or less for 1 minute to 10 minutes. Pressurization is preferably performed in air or an inert atmosphere. Because the electrolyte membrane 3 is heated and pressurized, it tends to expand in the direction of the arrow in Figure 8, but the expansion is suppressed by using the first seal 4 when bonding the first electrode 1 and the electrolyte membrane 3 together.

[0079] The member 103 shown in the process schematic diagram of FIG. 9 relates to a process for cooling the member 102 that has been heated and bonded. Thereafter, the member 102 is cooled. When the member 102 is cooled while maintaining a pressurized state, the electrolyte membrane 3 tends to shrink in the direction of the arrow shown for the member 103 in the process schematic diagram of FIG. 9. Because the first seal 4 is used both during heating and cooling, the electrolyte membrane 3 expands little when heated, resulting in little shrinkage during cooling. Furthermore, the first seal 4 suppresses deformation of the electrolyte membrane 3 during shrinkage, so that volumetric change of the electrolyte membrane 3 is suppressed during the process from heating and pressurizing to cooling and pressurizing.

[0080] The component 104 shown in the process schematic diagram of Figure 10 relates to the process of removing the first press plate 6 and the second press plate 7. After cooling, the press plate 6 and the press plate 7 are removed, and the component 104 shown in the process schematic diagram of Figure 10 is obtained.

[0081] The member 105 shown in the process schematic diagram of FIG. 11 relates to the step of peeling off the first seal 4. The first seal 4 is peeled off from the member 104 from which the press plates 6 and 7 have been removed. The first seal 4 is peeled off, for example, in the air or in a liquid. The liquid used to peel off the first seal 4 is preferably water, for example. Alternatively, the first seal 4 may be subjected to a treatment to make it easier to peel off.

[0082] The membrane electrode assembly 100 having the first seal 4 can be used in an electrochemical cell 300 or a stack 400, or the MEA 200 from which the first seal 4 has been removed can be used in the electrochemical cell 300 or the stack 400. A gasket may be provided when the first seal 4 of the member 105 is removed to form an MEA. The member 104 in FIG. 10 can be peeled off in air or water to obtain the member 105 shown in the process schematic diagram in FIG. 11.

[0083] The volume change of the electrolyte membrane 3 is suppressed during the process from heating and pressurizing to cooling and pressurizing, which prevents wrinkles from forming in the electrolyte membrane 3. If wrinkles form in the electrolyte membrane 3, hydrogen is more likely to cross over to the anode electrode side through gaps created by the wrinkles. This can increase the hydrogen concentration on the anode electrode side. The first seal 4 is firmly bonded to the outer periphery of the electrolyte membrane 3, which prevents both hydrogen leakage and hydrogen crossover.

[0084] A method for manufacturing the membrane electrode assembly 100 will be described with reference to the process schematics of Figures 12 to 16. The method for manufacturing the membrane electrode assembly 100 described with reference to the process schematics of Figures 12 to 16 relates to part of the manufacturing process of the membrane electrode assembly 100. The method for bonding the electrolyte membrane 3 and the second electrode 2 using the second seal 5 includes the steps of: placing the electrolyte membrane 3 provided on the press plate 6 (the electrolyte membrane 3 to which the first electrode 1 is bonded is also simply referred to as the electrolyte membrane 3 in the step of bonding the electrolyte membrane 3 and the first electrode 1) on the press plate 7; placing the second seal 5 having the second opening 5A opposite the second electrode 2 provided in the second opening 5A; heating the opposed members to bond them together; cooling the heated and bonded members; removing the press plates 6 and 7; and optionally peeling off the first seal 5.

[0085] The component 106 shown in the process schematic diagram of FIG. 12 relates to a process of placing an electrolyte membrane 3 provided on a first press plate 6, a second seal 5 provided on a second press plate 7, and a second electrode 2 provided in the second opening 5A opposite the second seal 5 having a second opening 5A. The component 106 includes an electrolyte membrane 3 provided on the first press plate 6, and a second electrode 2 provided on the second press plate 7. The second electrode 2 is housed in the second opening 5A of the second seal 5. The electrolyte membrane 3 is placed opposite the second seal 5 having the second opening 5A and the second electrode 2 provided in the second opening 5A.

[0086] The member 107 shown in the process schematic diagram of Fig. 13 relates to a process of heating and bonding facing members 106. The member 106 of Fig. 13 is bonded to the electrolyte membrane 3 with the second electrode 2 and the second seal 5 as the member 107 shown in the process schematic diagram of Fig. 13. In bonding, for example, heating is performed at 120°C to 180°C, and a pressure of 10 kg / cm is applied. 2 ] or more 30[kg / cm 2 ] or less for 1 minute to 10 minutes. Pressurization is preferably performed in air or an inert atmosphere. Because the electrolyte membrane 3 is heated and pressurized, it tends to expand in the direction of the arrow in Figure 13, but the expansion is suppressed by using the second seal 5 when bonding the second electrode 2 and the electrolyte membrane 3 together.

[0087] The member 108 shown in the process schematic diagram of FIG. 14 relates to a process for cooling the member 107 that has been heated and bonded together. Thereafter, the member 108 is cooled. When the member 108 is cooled while maintaining a pressurized state, the electrolyte membrane 3 tends to shrink in the direction of the arrow shown for the member 108 in the process schematic diagram of FIG. 14. Because the second seal 5 is used both during heating and cooling, the electrolyte membrane 3 expands less when heated, resulting in less shrinkage during cooling. Furthermore, the second seal 5 suppresses deformation of the electrolyte membrane 3 during shrinkage, so that volumetric change of the electrolyte membrane 3 is suppressed during the process from heating and pressurizing to cooling and pressurizing.

[0088] The component 109 shown in the process schematic diagram of Figure 15 relates to the process of removing the first press plate 6 and the second press plate 7. After cooling, the press plate 6 and the press plate 7 are removed, and the component 109 shown in the process schematic diagram of Figure 15 is obtained.

[0089] The member 111 shown in the process schematic diagram of FIG. 16 relates to the step of peeling off the second seal 5. The second seal 5 is peeled off from the member 109 from which the first press plate 6 and the second press plate 7 have been removed. The second seal 5 is peeled off, for example, in the air or in a liquid. The liquid used to peel off the second seal 5 is preferably water, for example. Alternatively, the second seal 5 may be subjected to a treatment to make it easier to peel off.

[0090] The form in which the membrane electrode assembly 100 having the first seal 4 is used in the electrochemical cell 300 or the stack 400, and the MEA 200 from which the first seal 4 is removed can be used in the electrochemical cell 300 or the stack 400. A gasket may be provided when the first seal 4 of the member 105 is removed to form an MEA. The member 104 in FIG. 10 can be peeled off in the atmosphere or in water to obtain the member 105 shown in the process schematic diagram of FIG. 11.

[0091] By suppressing the volume change of the electrolyte membrane 3 during the process from heating and pressurizing to cooling and pressurizing, the generation of wrinkles in the electrolyte membrane 3 can be suppressed. When wrinkles occur in the electrolyte membrane 3, hydrogen is likely to cross over to the anode electrode side from the voids caused by the wrinkles. Then, the hydrogen concentration on the anode electrode side may increase. Since the first seal 4 is firmly joined to the outer peripheral side of the electrolyte membrane 3, both the aforementioned hydrogen leak and hydrogen crossover can be suppressed.

[0092] When the second sheet 5 is used on the second electrode 2 side, after bonding the first electrode 1 to the electrolyte membrane 3, the second electrode 2 may be bonded to the electrolyte membrane 3, or after bonding the second electrode 2 to the electrolyte membrane 3, the first electrode 1 may be bonded to the electrolyte membrane 3, or the first electrode 1 and the second electrode 2 may be simultaneously bonded to the electrolyte membrane 3. When the second sheet 5 is not used on the second electrode 2 side, from the viewpoint of suppressing the generation of wrinkles, it is preferable to bond the second electrode 2 to the electrolyte membrane 3 after bonding the first electrode 1 to the electrolyte membrane 3. The second seal 5 may also be peeled off after bonding, and a gasket may be provided when forming the MEA.

[0093] Since the generation of wrinkles is suppressed during bonding, it is difficult for wrinkles to occur in the electrolyte membrane 3 even when the seal is peeled off. When peeling off the first seal 4 and the second seal 5, it is preferable to satisfy W1 < W = 0 < W2, L1 < L = 0 < L2, W1 < W11 < W2, and L1 < L11 < L2 from the viewpoint of facilitating peeling of the seal.

[0094] The electrolyte membrane 3 used in industrial hydrogen generation devices is large, for example, with one side measuring 10 cm or more, and is therefore susceptible to the effects of expansion and contraction of the electrolyte membrane 3. However, by employing the membrane electrode assembly 100 of the embodiment, the expansion and contraction of the electrolyte membrane 3 is suppressed, and the occurrence of wrinkles is suppressed even in a large membrane electrode assembly 100, contributing to improved reliability.

[0095] (Second embodiment) The second embodiment relates to an electrochemical cell. Fig. 12 shows a cross-sectional view of an electrochemical cell 200 according to the second embodiment. The electrochemical cell 200 will be described below using water electrolysis as an example, but hydrogen can also be generated by decomposing ammonia or the like in addition to water.

[0096] As shown in Fig. 17, an electrochemical cell 200 of the second embodiment includes a first electrode (anode) 1, a second electrode (card) 2, an electrolyte membrane 3, an anode power supply 21, a cathode power supply 22, a separator 23, and a separator 24. In the electrochemical cell 200, when the first seal 4 and the second seal 5 of the membrane electrode assembly 100 are attached to the electrolyte membrane 3, the electrochemical cell 200 shown in the schematic diagram of Fig. 17 is used. In the electrochemical cell 200, when the first seal 4 and the second seal 5 of the membrane electrode assembly 100 are peeled off from the electrolyte membrane 3, the first seal 4 and the second seal 5 of the electrochemical cell 200 shown in the schematic diagram of Fig. 17 can be replaced with gaskets or the like.

[0097] It is preferable to use a membrane electrode assembly 100 in which a first electrode (anode) 1, a second electrode (card) 2, and an electrolyte membrane 3 are joined together. The anode power supply 21 and the cathode power supply 23 may be any material that allows gas and water to pass through. The anode power supply 21 and the cathode power supply 22 may be integrated with separators 24, 24, respectively. Specifically, the separator may have a flow path through which a hydrogen source such as water or gas flows, or may have a porous body, but is not limited to these. An electrochemical cell 200 using the membrane electrode assembly 100 of the embodiment suppresses hydrogen leakage and is highly reliable.

[0098] In the electrochemical cell 200 of Figure 17, electrodes (not shown) are connected to an anode power supply 21 and a cathode power supply 23, and a reaction occurs at the anode 1 and cathode 2. For example, water is supplied to the anode 1, where the water is decomposed into protons, oxygen, and electrons. The electrode support and power supply are porous, and this porous body functions as a flow path plate. The produced water and unreacted water are discharged, and the protons and electrons are used in the cathode reaction. In the cathode reaction, protons and electrons react to produce hydrogen. Either or both of the produced hydrogen and oxygen are used, for example, as fuel for the fuel cell.

[0099] (Third embodiment) The third embodiment relates to a stack. Fig. 18 is a schematic cross-sectional view showing a stack 300 of the third embodiment. The stack 300 of the third embodiment shown in Fig. 18 has a plurality of MEAs 100 or electrochemical cells 200 connected in series. Clamping plates 31 and 32 are attached to both ends of the MEA or electrochemical cell.

[0100] Since the amount of hydrogen produced by an electrochemical cell 200 consisting of one MEA 100 is small, a large amount of hydrogen can be obtained by connecting a plurality of electrochemical cells 200 in series to form a stack 300.

[0101] (Fourth embodiment) The fourth embodiment relates to an electrolysis device. Fig. 19 shows a conceptual diagram of an electrolysis device according to a fifth embodiment. An electrochemical cell 200 or a stack 300 is used in a hydrogen generation device 400. The electrolysis device in Fig. 19 is for water electrolysis. An electrolysis device for water electrolysis will be described. For example, when generating hydrogen from ammonia, it is preferable to employ a device with a different configuration that uses a membrane electrode assembly 100.

[0102] As shown in FIG. 19 , a water electrolysis stack 300 is constructed by stacking water electrolysis unit cells in series. A power supply 41 is attached to the water electrolysis stack 300, and a voltage is applied 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 water electrolysis stack 300. Water is delivered to the mixing tank 43 by a pump 46 from an ion-exchange water production unit 44, and the water passes through a check valve 47 from the gas-liquid separator 42, mixes with the gas, liquid, and circulates to the anode. Oxygen generated at the anode passes through the gas-liquid separator 42 to produce oxygen gas. Meanwhile, a hydrogen purifier 49 is connected continuously to the gas-liquid separator 48 on the cathode side to produce high-purity hydrogen. Impurities are discharged via a pathway with a valve 50 connected to the hydrogen purifier 49. To stably control the operating temperature, the stack and mixing tank can be heated, and the current density during pyrolysis can be controlled.

[0103] Examples of the embodiment will be described below.

[0104] Example A Preparation of the anode (first electrode 1) The substrate is a Ti nonwoven fabric substrate measuring 25 cm x 25 cm and 200 μm thick. Nickel and iridium are sputtered onto the titanium substrate to form a sheet layer. Then, nickel alone is sputtered to form a gap layer. This process of forming the sheet layer and gap layer is repeated 40 times until the Ir concentration per area reaches 0.2 mg / cm. 2 Then, by washing with sulfuric acid, the nickel-free catalyst structure is obtained.

[0105] Fabrication of cathode (second electrode 2) A carbon paper Toray 060 (manufactured by Toray Industries, Inc.) with a size of 25 cm × 25 cm and a carbon layer of 190 μm in thickness was prepared as a substrate. A Pt catalyst was loaded onto this substrate with a loading density of 0.1 mg / cm. 2A catalyst layer having a laminated structure including a void layer is formed by sputtering so that the thickness of the porous catalyst layer is 1 / 3 of the thickness of the electrode. This electrode is used as a standard cathode in the examples and comparative examples.

[0106] The electrolyte membrane 3 is a 30 cm x 30 cm Nafion 115 manufactured by Chemours, which is sprayed with a solution of tetraammine platinum diluted to 11 wt% with water. Before spraying, the Nafion 115 is masked with tape to match the Pt impregnation size conditions in Table 1. 10 minutes after spraying, the membrane is rinsed with pure water and finally boiled for 1 hour in 10 wt% nitric acid at 80°C to obtain an electrolyte membrane 3 impregnated with Pt particles.

[0107] [Table 1]

[0108] The first seal 4 and the second seal 5 are made of a 30 cm x 30 cm sealing material with an EPDM rubber (ethylene propylene diene rubber) sheet on the top, a PET film in the middle, and an EPDM rubber sheet on the bottom. The thickness of the first seal 4 and the second seal 5 is thinner than that of the cathode 2 and the anode 1. In this example, a sealing material with a thickness of 160 μm is used. Since the first seal 4 and the second seal 5 are placed on the outer periphery of the anode 1 and the cathode 2, the center is cut to fit the electrode size, and the first opening 4A and the second opening 5A are formed, leaving the outer periphery.

[0109] The press plates used, from the side closest to the electrode, were a 32 cm x 32 cm, 0.1 mm thick Kapton sheet, on top of which was a 32 cm x 32 cm, 2 mm thick silicone rubber sheet, and finally a 32 cm x 32 cm, 1 mm thick stainless steel plate.Two sets of this combination were prepared and sandwiched between the anode and cathode sides.

[0110] The MEA is integrated using a hot press. First, a cathode is placed on the Kapton sheet side of the press plate, and a sealant is placed around its periphery. A Pt-impregnated electrolyte membrane 3 is placed on top of this, and then a sealant is placed around the anode and periphery. Finally, a press plate is placed with the Kapton sheet side facing out.

[0111] Next, it is placed in a hot press and heated at 160°C and 20 kg / cm 2 ] for 3 minutes, and then 25 [℃], 20 [kg / cm 2 ] and press-cool for 3 minutes to obtain an MEA.

[0112] The level of wrinkles on the film was judged based on the appearance at this time using the following criteria, which are shown in Table 2. A: No wrinkles at all B: Wavy wrinkles are visible C: Wrinkles with 1 to 3 membranes folded over are visible D: Four or more overlapping wrinkles are visible

[0113] [Table 2]

[0114] <Production of a single cell> The resulting MEA and gasket were placed between two separators with flow channels to create a PEEC single cell (electrochemical cell). 180 μm EPDM sheets were placed on the anode and cathode as gaskets. A back pressure valve was also installed at the hydrogen side outlet of the separator with flow channels, allowing the internal hydrogen pressure to be increased.

[0115] Next, the MEAs of Example A and Comparative Example A are evaluated. The measurement temperature is 80°C, and the current density is 2 A / cm 2] and steady-state operation is carried out. Performance is evaluated using a gas chromatograph to measure the amount of hydrogen cross-leakage [ppm] from the cathode to the anode when the pressure on the hydrogen side is increased using the back pressure valve, as the hydrogen concentration in oxygen. The amount of hydrogen leakage [ppm] is also calculated by taking the difference between the amount of hydrogen produced converted from the applied current and the amount of hydrogen obtained, and then compared. The amount of hydrogen leakage is the sum of the amount of hydrogen that moved from the cathode to the anode due to hydrogen cross-leakage, the amount of hydrogen that reacted with oxygen on the anode and recombined to convert to water, and the amount of hydrogen that leaked to the outside through the gaps in the gasket. Note that the device cannot measure values ​​above 20%. The amount of hydrogen leakage at this time was determined based on the following criteria A to C, and is shown in Table 2. A: 10,000 ppm or less at 5 MPa B: 400,000 ppm or less at 5 MPa C: When it exceeds 400,000 ppm at 5 MPa

[0116] Table 2 shows that the presence of a sealing material and a slightly smaller Pt impregnation size than electrolyte membrane 3 reduces wrinkles, crossover, and hydrogen leakage. It also shows that Pt impregnation is most effective against hydrogen crossover when applied to both sides or the anode surface. However, no particular correlation was found between the formation of wrinkles and hydrogen leakage to the outside and the Pt impregnation surface.

[0117] There was a tendency for the amount of hydrogen leakage to increase slightly as the Pt impregnation size increased, but this indicates that the presence of Pt reduces the friction coefficient at the edge, making it more likely to become insufficient in sealing.However, the increase in leakage amount was slight, and not at a level that would be a problem within the scope of this study.

[0118] In Comparative Examples A1 to A3, although there is a sealing material, the Pt impregnation size is the same as that of the electrolyte membrane 3. In this case, it can be seen that wrinkles are easily formed, and although the amount of hydrogen crossover is small, hydrogen leakage increases rapidly when pressurized. It can be said that the wrinkles in the electrolyte membrane 3 cause the gasket to become loose, allowing hydrogen to leak out.

[0119] In Comparative Example A4, Pt impregnation was not performed. In this case, wrinkles did not appear in the electrolyte membrane 3, but it was found that hydrogen crossover increased.

[0120] In Comparative Examples A4 to A7, no sealing material was used, and it was found that folding and wrinkles occurred in the electrolyte membrane 3, causing hydrogen to leak to the outside.

[0121] In Comparative Examples A8 to A13, the size of the Pt impregnation was set smaller than the membrane, but since there was no sealing material, wrinkles occurred, and it was found that hydrogen leaked out.

[0122] Example B In Example B-1, an MEA was produced under the same conditions as in Example A-1, except for changing the amount of Pt impregnated into the electrolyte membrane 3. Table 3 shows the Pt impregnation amounts and evaluation results for Examples B-1 to B-3.

[0123] [Table 3]

[0124] Example B shows that increasing the amount of Pt slightly reduces the amount of hydrogen crossover, but conversely increases the amount of hydrogen leakage. This shows that the presence of Pt reduces the friction coefficient at the end, making it more susceptible to insufficient sealing. However, the increase in leakage is slight, and is not at a level that would be a problem within the scope of this study.

[0125] (Comparative example C) As Comparative Example C, evaluation was performed using a sealing material made of only EPDM rubber, a sealing material made of only PET film, and a sealing material with a two-layer structure of EPDM rubber and PET film. An MEA was produced under the same conditions as in Example A-1, except for the different sealing materials. When the sealing material of Comparative Example C was used, wrinkles and hydrogen leakage were evaluated in the same manner as in Example A, and the results are shown in Table 4.

[0126] [Table 4]

[0127] When the sealing material has a laminated structure of two or less layers or a single-phase structure, it is difficult to prevent wrinkles in the electrolyte membrane 3 and hydrogen leakage.

[0128] In the specification, some elements are represented only by element symbols.

[0129] The technical solutions of the embodiments are described below. [Technical proposal 1] A first electrode; A second electrode; an electrolyte membrane provided between the first electrode and the second electrode; a first seal provided on an outer periphery of the first electrode, having a first opening, accommodating the first electrode within the first opening, and in contact with the electrolyte membrane; or a second seal having a second opening, accommodating the second electrode within the second opening, and in contact with the electrolyte membrane; and the first seal; A membrane electrode assembly having: [Technical proposal 2] A membrane electrode assembly according to Technical Scheme 1, wherein a precious metal region containing precious metal particles containing one or more precious metals selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru is present on the first electrode side of the electrolyte membrane. [Technical proposal 3] When the width of the electrolyte membrane is W1 and the width of the precious metal region is W2, W1-W2 satisfies 0.01 times or more and 0.98 times or less of W1, A membrane electrode assembly according to Technical Scheme 2, wherein, when the length of the electrolyte membrane is L1 and the length of the precious metal region is L2, L1-L2 is 0.01 times or more and 0.98 times or less of L1. [Technical proposal 4] When the width of the electrolyte membrane is W1, the width of the noble metal region is W2, and the width of the first electrode is W3, W1>W2>W3 is satisfied; A membrane electrode assembly according to Technical Scheme 2 or 3, wherein L1>L2>L3 is satisfied, where L1 is the length of the electrolyte membrane, L2 is the length of the precious metal region, and L3 is the length of the first electrode. [Technical proposal 5] When the width of the electrolyte membrane is W1, the width of the first electrode is W2, the width of the precious metal region is W3, the length of the electrolyte membrane is L1, the length of the first electrode is L2, and the length of the precious metal region is length 3, the noble metal region is provided between 0.8 and 0.99 times W1 in a width direction from the center of the surface of the electrolyte membrane on the first electrode side, A membrane electrode assembly described in any one of technical proposals 2 to 4, wherein the precious metal region is located between the center of the first electrode side surface of the electrolyte membrane and a distance of 0.8 to 0.99 times L1 in the width direction. [Technical proposal 6] the first seal includes a first rubber sheet, a first resin sheet, and a second rubber sheet; the first rubber sheet, the first resin sheet, and the second rubber sheet are laminated together; the first resin sheet is located between the first rubber sheet and the second rubber sheet, the second seal includes a third rubber sheet, a second resin sheet, and a fourth rubber sheet; the third rubber sheet, the second resin sheet, and the fourth rubber sheet are laminated together, A membrane electrode assembly according to any one of technical proposals 1 to 5, wherein the second resin sheet is positioned between the third rubber sheet and the fourth rubber sheet. [Technical proposal 7] The Young's modulus of the first seal is 0.001 [GPa] or more and 5 [GPa] or less within a range of 5 [°C] or more and 100 [°C] or less, A membrane electrode assembly described in any one of technical proposals 1 to 6, wherein the Young's modulus of the second seal is 0.001 [GPa] or more and 5 [GPa] or less within the range of 5 [°C] or more and 100 [°C] or less. [Technical proposal 8] the first seal includes a first rubber sheet, a first resin sheet, and a second rubber sheet; the first rubber sheet, the first resin sheet, and the second rubber sheet are laminated together; the first resin sheet is located between the first rubber sheet and the second rubber sheet, an inner surface of the first rubber sheet contacts a side surface of the first electrode; a surface of the first rubber sheet facing the electrolyte contacts the electrolyte membrane; an inner surface of the first resin sheet contacts a side surface of the first electrode; the second seal includes a third rubber sheet, a second resin sheet, and a fourth rubber sheet; the third rubber sheet, the second resin sheet, and the fourth rubber sheet are laminated together, the second resin sheet is located between the third rubber sheet and the fourth rubber sheet, an inner surface of the third rubber sheet contacts a side surface of the second electrode; a surface of the third rubber sheet facing the electrolyte contacts the electrolyte membrane; 8. The membrane electrode assembly according to any one of Technical Schemes 1 to 7, wherein the inner surface of the second resin sheet is in contact with the side surface of the second electrode. [Technical proposal 9] 6. The membrane electrode assembly according to any one of Technical Schemes 2 to 5, wherein the first seal is in contact with the electrolyte membrane in a region where the noble metal region is not present. [Technical proposal 10] the first seal contacts the electrolyte membrane in a region where the noble metal region is not present; 10. The membrane electrode assembly according to any one of Technical Schemes 2 to 5 and 9, wherein the first seal is in contact with the electrolyte membrane in a region where the noble metal region is present. [Technical proposal 11] the first electrode has a substrate and a catalyst layer; The amount of metal contained per area of ​​the catalyst layer is 0.02 [g / cm 2 ] or more 1.0[g / cm 2 ] or less, The membrane / electrode assembly according to any one of Technical Schemes 1 to 10, wherein the porosity of the catalyst layer is 10% or more and 90% or less. [Technical proposal 12] When the width of the electrolyte membrane is W1 and the width of the first electrode is W3, W1-W3 satisfies 0.01 times or more and 0.2 times or less of W1, A membrane electrode assembly according to any one of technical proposals 1 to 11, wherein, when the length of the electrolyte membrane is L1 and the length of the first electrode is L3, L1-L3 is 0.01 to 0.2 times L1. [Technical proposal 13] When the width of the electrolyte membrane is W1 and the width of the second electrode is W4, W1-W4 satisfies 0.01 times or more and 0.2 times or less of W1, A membrane electrode assembly according to any one of technical proposals 1 to 12, wherein, when the length of the electrolyte membrane is L1 and the length of the second electrode is L4, L1-L4 is 0.01 to 0.2 times L1. [Technical proposal 14] a step of placing the electrolyte membrane provided on the first press plate, a first seal provided on a second press plate, and a first electrode provided in the first opening facing each other; a step of heating and bonding the facing members together; a step of cooling the heated and bonded members; removing the first press plate and the second press plate; optionally peeling the first seal; A method for bonding an electrolyte membrane and a first electrode using a first seal having the above structure. [Technical proposal 15] a step of placing the electrolyte membrane provided on the first press plate opposite a second seal provided on a second press plate and having a second opening, and a second electrode provided in the second opening; a step of heating and bonding the facing members together; a step of cooling the heated and bonded members; removing the first press plate and the second press plate; Optionally peeling the second seal; A method for bonding an electrolyte membrane and a second electrode using a second seal having the above structure. [Technical proposal 16] the first seal includes a first rubber sheet, a first resin sheet, and a second rubber sheet; the first rubber sheet, the first resin sheet, and the second rubber sheet are laminated together; the first resin sheet is located between the first rubber sheet and the second rubber sheet, an inner surface of the first rubber sheet contacts a side surface of the first electrode; a surface of the first rubber sheet facing the electrolyte contacts the electrolyte membrane; an inner surface of the first resin sheet contacts a side surface of the first electrode; the second seal includes a third rubber sheet, a second resin sheet, and a fourth rubber sheet; the third rubber sheet, the second resin sheet, and the fourth rubber sheet are laminated together, the second resin sheet is located between the third rubber sheet and the fourth rubber sheet, an inner surface of the third rubber sheet contacts a side surface of the second electrode; a surface of the third rubber sheet facing the electrolyte contacts the electrolyte membrane; The bonding method described in Technical Scheme 14 or 15, wherein the inner surface of the second resin sheet contacts the side surface of the second electrode. [Technical proposal 17] Using the membrane electrode assembly according to any one of technical proposals 1 to 13, The electrochemical cell wherein the first electrode is an anode electrode. [Technical proposal 18] Using the membrane electrode assembly according to any one of technical proposals 1 to 13, The first electrode of the stack is an anode electrode. [Technical proposal 19] Using the stack described in Technical Proposal 18, The electrolysis device, wherein the first electrode is an anode electrode or a cathode electrode.

[0130] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. Although a PEMEC has been described as a water electrolysis cell, the present invention can be similarly applied to other electrolysis cells. These novel embodiments described above can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit and scope of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the invention and its equivalents as defined in the accompanying claims. [Explanation of symbols]

[0131] 1 1st electrode 2 2nd electrode 3 Electrolyte membrane 4. First Seal 4A 1st opening 5 Second Seal 6. First press plate 7 Second press plate 21 Anode power supply 22 cathode current feeder 23 Separator 24 Separator 31 Clamping plate 32 Clamping plate 41 Power supply 42 Gas-liquid separation equipment 43 Mixing Tank 44 Ion exchange water production equipment 46 Pump 47 Check valve 48 Gas-liquid separation equipment 49 Hydrogen Purification Equipment 50 valves 100 Membrane electrode assembly 200 electrochemical cells 300 stacks 400 Electrolyzer

Claims

1. A first electrode; A second electrode; an electrolyte membrane provided between the first electrode and the second electrode; a first seal provided on an outer periphery of the first electrode, having a first opening, accommodating the first electrode within the first opening, and in contact with the electrolyte membrane; or a second seal having a second opening, accommodating the second electrode within the second opening, and in contact with the electrolyte membrane; and the first seal; and the first seal includes a first rubber sheet, a first resin sheet, and a second rubber sheet; the first rubber sheet, the first resin sheet, and the second rubber sheet are laminated together; the first resin sheet is located between the first rubber sheet and the second rubber sheet, a precious metal region including precious metal particles containing one or more precious metals selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru is present on the first electrode side of the electrolyte membrane, When the width of the electrolyte membrane is W1 and the width of the precious metal region is W2, W1-W2>0 is satisfied; A membrane electrode assembly in which L1-L2>0 is satisfied, where L1 is the length of the electrolyte membrane and L2 is the length of the noble metal region.

2. When the width of the electrolyte membrane is W1 and the width of the precious metal region is W2, W1-W2 satisfies 0.01 times or more and 0.98 times or less of W1, 2. The membrane electrode assembly according to claim 1, wherein L1 is the length of the electrolyte membrane and L2 is the length of the noble metal region, and L1-L2 is 0.01 to 0.98 times L1.

3. W1-W2 satisfies the condition of 0.02 times or more and 0.2 times or less of W1, 2. The membrane electrode assembly according to claim 1, wherein L1-L2 is 0.02 to 0.2 times L1.

4. When the width of the electrolyte membrane is W1, the width of the noble metal region is W2, and the width of the first electrode is W3, W1>W2>W3 is satisfied; 2. The membrane electrode assembly according to claim 1, wherein L1 > L2 > L3 is satisfied, where L1 is the length of the electrolyte membrane, L2 is the length of the noble metal region, and L3 is the length of the first electrode.

5. W2 / W1 is equal to or greater than 0.8 and less than 1, 2. The membrane electrode assembly according to claim 1, wherein L2 / L1 is 0.8 or more and less than 1.

6. The membrane electrode assembly has the first seal and the second seal, the second seal includes a third rubber sheet, a second resin sheet, and a fourth rubber sheet; the third rubber sheet, the second resin sheet, and the fourth rubber sheet are laminated together; 2. The membrane electrode assembly according to claim 1, wherein the second resin sheet is located between the third rubber sheet and the fourth rubber sheet.

7. The membrane electrode assembly has the first seal and the second seal, The Young's modulus of the first seal is 0.001 GPa or more and 5 GPa or less within a range of 5°C or more and 100°C or less, 2. The membrane electrode assembly according to claim 1, wherein the second seal has a Young's modulus of 0.001 GPa or more and 5 GPa or less within a temperature range of 5° C. or more and 100° C. or less.

8. The membrane electrode assembly has the first seal and the second seal, an inner surface of the first rubber sheet contacts a side surface of the first electrode; a surface of the first rubber sheet facing the electrolyte contacts the electrolyte membrane; an inner surface of the first resin sheet contacts a side surface of the first electrode; the second seal includes a third rubber sheet, a second resin sheet, and a fourth rubber sheet; the third rubber sheet, the second resin sheet, and the fourth rubber sheet are laminated together; the second resin sheet is located between the third rubber sheet and the fourth rubber sheet, an inner surface of the third rubber sheet contacts a side surface of the second electrode; a surface of the third rubber sheet facing the electrolyte contacts the electrolyte membrane; The membrane electrode assembly according to claim 1 , wherein an inner surface of the second resin sheet contacts a side surface of the second electrode.

9. The membrane electrode assembly according to claim 2 , wherein the first seal contacts the electrolyte membrane in a region where the noble metal region is not present.

10. the first seal contacts the electrolyte membrane in a region where the noble metal region is not present; The membrane electrode assembly according to claim 2 , wherein the first seal contacts the electrolyte membrane in a region where the noble metal region is present.

11. the first electrode has a substrate and a catalyst layer; The amount of metal contained per area of ​​the catalyst layer is 0.02 [g / cm ２ ] or more 1.0 [g / cm ２ ] or less, 2. The membrane electrode assembly according to claim 1, wherein the porosity of the catalyst layer is 10% or more and 90% or less.

12. When the width of the electrolyte membrane is W1 and the width of the first electrode is W3, W1-W3 satisfies 0.01 times or more and 0.2 times or less of W1, 2. The membrane electrode assembly according to claim 1, wherein, when the length of the electrolyte membrane is L1 and the length of the first electrode is L3, L1-L3 is 0.01 to 0.2 times L1.

13. When the width of the electrolyte membrane is W1 and the width of the second electrode is W4, W1-W4 satisfies 0.01 times or more and 0.2 times or less of W1, 2. The membrane electrode assembly according to claim 1, wherein, when the length of the electrolyte membrane is L1 and the length of the second electrode is L4, L1-L4 is 0.01 to 0.2 times L1.

14. Using the membrane electrode assembly according to any one of claims 1 to 13, The electrochemical cell wherein the first electrode is an anode electrode.

15. Using the membrane electrode assembly according to any one of claims 1 to 13, The stack wherein the first electrode is an anode electrode.

16. Using the stack according to claim 15, The electrolysis device, wherein the first electrode is an anode electrode or a cathode electrode.

Images