Membrane electrode assemblies, electrochemical cells, stacks, and electrolytic devices

Abstract

To provide a membrane electrode assembly with high reliability.SOLUTION: A membrane electrode assembly of an embodiment includes: a first electrode including a first diffusion layer and a first catalyst layer; a second electrode for generating hydrogen, the second electrode including a second diffusion layer, a second catalyst layer including a porous catalyst layer including a porous precious metal or sheet-like precious metal, and a hydrophobic moisture management layer provided between the second catalyst layer and the second diffusion layer, the hydrophobic moisture management layer including carbon particles and carbon fibers, the carbon fibers constituting 1 wt.% or more and 20 wt.% or less of the weight of the second diffusion layer; and an electrolyte membrane provided between the first electrode and the second electrode, the first catalyst layer being provided between the first diffusion layer and the electrolyte membrane, and the second catalyst layer being provided between the second diffusion layer and the electrolyte membrane.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to membrane electrode assemblies, electrochemical cells, stacks, and electrolysis devices. Background Art

[0002] In recent years, electrochemical cells have been extensively researched. Among electrochemical cells, for example, polymer electrolyte membrane electrolysis cells (PEMEC) are expected to be used for hydrogen production in large-scale energy storage systems. To ensure sufficient durability and electrolytic performance, platinum (Pt) nanoparticle catalysts are generally used for the cathode of PEMEC, and noble metal catalysts such as iridium (Ir) nanoparticle catalysts are generally used for the anode. Methods for obtaining hydrogen from ammonia have also been studied. Prior Art Literature Non-Patent Literature

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

[0004] The problem to be solved by the present invention is to provide a highly reliable membrane electrode assembly, electrochemical cell, stack, and electrolysis device. Means for Solving the Problems

[0005] The film electrode assembly of the embodiment includes a first electrode having a first diffusion layer and a first catalyst layer including a porous catalyst layer containing a noble metal porous material or a sheet-like noble metal; a second catalyst layer including a second diffusion layer and a porous catalyst layer containing a noble metal porous material or a sheet-like noble metal; and a layer provided between the second catalyst layer and the second diffusion layer, containing carbon particles, carbon fibers in an amount of 1 wt% to 20 wt% of the weight of the second diffusion layer, and a water-repellent material, with a film thickness of 10 μm to 50 μm. below The device comprises a hydrophobic moisture management layer, a second electrode that generates hydrogen, and an electrolyte membrane provided between the first electrode and the second electrode, wherein the first catalyst layer is provided between the first diffusion layer and the electrolyte membrane, and the second catalyst layer is provided between the second diffusion layer and the electrolyte membrane. [Brief explanation of the drawing]

[0006] [Figure 1] This is a schematic cross-sectional view of the membrane electrode assembly of the first embodiment. [Figure 2] This is a micrograph of the catalyst unit of the first embodiment. [Figure 3] This is a schematic diagram of the electrochemical cell of the second embodiment. [Figure 4] This is a schematic diagram of the stack according to the third embodiment. [Figure 5] This is a schematic diagram of the electrolytic apparatus according to the fourth embodiment. [Modes for carrying out the invention]

[0007] The embodiments will be described below with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals.

[0008] The physical properties described herein are those obtained at a temperature of 25°C and a pressure of 1 atom. The thickness of each component is the average value over the distance in the lamination direction.

[0009] (First Embodiment) The membrane electrode assembly of this embodiment comprises a first electrode having a first diffusion layer and a first catalyst layer; a second catalyst layer having a second diffusion layer and a porous catalyst layer containing a noble metal porous body or a sheet-like noble metal; a second electrode that generates hydrogen and is provided between the second catalyst layer and the second diffusion layer, and having a hydrophobic moisture management layer containing carbon particles and carbon fibers in an amount of 1 wt% to 20 wt% of the weight of the second diffusion layer; and an electrolyte membrane provided between the first electrode and the second electrode, wherein the first catalyst layer is provided between the first diffusion layer and the electrolyte membrane, and the second catalyst layer is provided between the second diffusion layer and the electrolyte membrane.

[0010] In the following embodiments, water electrolysis will be used as an example.

[0011] Furthermore, the operating method of the electrolytic apparatus in this embodiment can be used as an operating method for an ammonia electrolytic apparatus. The membrane electrode assembly 100 in this embodiment can be used as a membrane electrode assembly for an electrolytic apparatus for ammonia synthesis. The operating method of the electrolytic apparatus in this embodiment can be used as an operating method for an electrolytic apparatus used in electrolysis for ammonia synthesis, in which ultrapure water is supplied to the anode, the water is decomposed at the anode to produce protons and oxygen, the generated protons pass through the electrolyte membrane, and nitrogen supplied to the cathode combines with the protons and electrons to produce ammonia.

[0012] Furthermore, the operating method of the electrolytic apparatus in this embodiment can be used for operating an electrolytic apparatus that generates hydrogen by electrolyzing ammonia. The membrane electrode assembly 100 in this embodiment can be used for an apparatus that generates hydrogen by electrolyzing ammonia. The operating method of the electrolytic apparatus in this embodiment can be used for operating an electrolytic apparatus used for ammonia decomposition electrolysis, in which ammonia is supplied to the cathode, the ammonia is decomposed at the cathode to generate protons and nitrogen, the generated protons pass through the electrolyte membrane, and hydrogen is generated when the protons and electrons combine at the anode.

[0013] Figure 1 is a schematic cross-sectional view of the film electrode assembly 100 of this embodiment. Figure 2 is a micrograph of the catalyst unit of this embodiment.

[0014] The membrane electrode assembly 100 of the present embodiment will be described with reference to FIG. 1 and FIG. 2.

[0015] The membrane electrode assembly 100 includes a first electrode 2, a second electrode 12, and an electrolyte membrane 20.

[0016] The first electrode 2 is, for example, an anode electrode. The first electrode 2 includes a first diffusion layer 4 and a first catalyst layer 6.

[0017] The second electrode 12 is, for example, a cathode electrode. The second electrode 12 includes a second diffusion layer 14, a second catalyst layer 16, and a hydrophobic water management layer 18.

[0018] The electrolyte membrane 20 is provided between the first electrode 2 and the second electrode 12. The first catalyst layer 6 is provided between the first diffusion layer 4 and the electrolyte membrane 20. The second catalyst layer 16 is provided between the second diffusion layer 14 and the electrolyte membrane 20. The hydrophobic water management layer 18 is provided between the second catalyst layer 16 and the second diffusion layer 14.

[0019] Here, an X direction (X axis), a Y direction (Y axis) perpendicularly intersecting the X direction (X axis), and a Z direction (Z axis) perpendicularly intersecting both the X direction (X axis) and the Y direction (Y axis) are defined. The first diffusion layer 4 of the first electrode 2, the first catalyst layer 6, the electrolyte membrane 20, the second diffusion layer 14 of the second electrode 12, the second catalyst layer 16, and the hydrophobic water management layer 18 extend, for example, in the X direction and the Y direction. The first diffusion layer 4 of the first electrode 2, the first catalyst layer 6, the electrolyte membrane 20, the second diffusion layer 14 of the second electrode 12, the second catalyst layer 16, and the hydrophobic water management layer 18 extend in the X direction and the Y direction, for example. Further, the first electrode 2, the electrolyte membrane 20, and the second electrode 12 are laminated in the Z direction, for example.

[0020] As the first diffusion layer 4, it is preferable to use a porous and highly conductive material. The first diffusion layer 4 is a porous member through which gases and liquids can pass. The first diffusion layer 4 is, for example, carbon paper or a metal mesh. As the metal mesh, a porous substrate of valve metal is preferred. As the porous substrate of valve metal, 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 is preferred, or a porous substrate containing one metal selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony is preferred.

[0021] In this embodiment, the first diffusion layer 4 is particularly preferably a porous substrate of valve metal containing titanium.

[0022] The thickness of the first diffusion layer 4 is, for example, 50 μm or more and 200 μm or less.

[0023] The first catalyst layer 6 is provided between the first diffusion layer 4 and the electrolyte membrane 20. The first catalyst layer 6 contains a catalyst metal. Preferably, the first catalyst layer 6 consists of catalyst metal particles, and the catalyst metal is not supported on a carrier. Preferably, the first catalyst layer 6 has a porous catalyst layer, or a laminated structure including a porous structure or void layer. The catalyst metal is not particularly limited, but preferably includes one or more selected from the group consisting of Ir, Ru, and Pt. Preferably, the catalyst metal is a metal, alloy, or metal oxide.

[0024] The amount of metal per unit area of ​​the first catalyst layer 6 is 0.02 [mg / cm²] 2 ] or more 1.0[mg / cm 2 Preferably less than or equal to 0.05 [mg / cm³]. 2 ] or more 0.5[mg / cm 2 The sum of these masses can be measured, for example, using an ICP mass spectrometer (Inductively Coupled Plasma-Mass Spectrometer: ICP-MS).

[0025] The thickness of the first catalyst layer 6 is, for example, 0.1 μm or more and 20 μm or less.

[0026] The porosity of the first catalyst layer 6 is preferably 10% to 90%, and more preferably 30% to 70%.

[0027] Furthermore, an intermediate layer (not shown) may be provided between the first diffusion layer 4 and the first catalyst layer 6.

[0028] It is preferable to use a porous and highly conductive material for the second diffusion layer 14. The second diffusion layer 14 is a porous member that allows gases and liquids to pass through. The second diffusion layer 14 is, for example, carbon paper or a metal mesh. As the metal mesh, a porous substrate of valve metal is preferred. As the porous substrate of valve metal, 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 of one metal selected from the group consisting of titanium, aluminum, tantalum, niobium, hafnium, zirconium, zinc, tungsten, bismuth, and antimony is preferred.

[0029] The second catalyst layer 16 contains a catalyst metal. Preferably, the second catalyst layer 16 consists of catalyst metal particles, and the catalyst metal is not supported on a carrier. Preferably, the second catalyst layer 16 is a porous catalyst layer. The catalyst metal is not particularly limited, but for example, it includes 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.

[0030] The amount of metal per unit area of ​​the second catalyst layer 16 is preferably 0.02 [mg / cm²] or more and 1.0 [mg / cm²] or less, and more preferably 0.05 [mg / cm²] or more and 0.5 [mg / cm²] or less. This sum of masses can be measured, for example, with an ICP mass spectrometer (Inductively Coupled Plasma-Mass Spectrometer: ICP-MS).

[0031] The porosity of the second catalyst layer 16 is preferably 10% to 90%, and more preferably 30% to 70%.

[0032] The thickness of the second catalyst layer 16 is, for example, 0.1 μm or more and 2 μm or less.

[0033] Figure 2(A) shows a scanning electron microscope (SEM) image of a porous catalyst layer containing a porous noble metal or a sheet-like noble metal. Figures 2(B) and 2(C) show SEM images of the porous structure of the porous catalyst layer containing a porous noble metal or a sheet-like noble metal. In the case of a laminated structure including void layers, it is desirable for adjacent nanosheets to be partially integrated. Durability and robustness can be further improved by introducing a nanoceramic material layer into the laminated structure, or by placing a porous nanocarbon layer containing fibrous carbon between adjacent nanosheets or material layers. Such a porous catalyst layer containing a porous noble metal or a sheet-like noble metal can be used for the first catalyst layer 6 and the second catalyst layer 16.

[0034] The hydrophobic moisture management layer 18 is a porous, hydrophobic layer. The hydrophobic moisture management layer 18 contains carbon particles, carbon fibers in an amount of 1 wt% to 20 wt% of the weight of the second diffusion layer 14, and a water-repellent material. If the amount of carbon fibers in the hydrophobic moisture management layer 18 is less than 1 wt% of the weight of the second diffusion layer 14, insufficient diffusion prevents the generated hydrogen gas from being properly discharged to the flow channel side, causing gas to accumulate between the electrolyte membrane and the catalyst layer, leading to delamination of the electrolyte membrane and the catalyst layer. Furthermore, if the amount of carbon fibers in the hydrophobic moisture management layer 18 exceeds 20 wt% of the weight of the second diffusion layer 14, the porosity of the hydrophobic moisture management layer increases, reducing its conductivity.

[0035] The thickness of the hydrophobic moisture management layer 18 is preferably 10 μm or more and 50 μm or less. If it is less than 10 μm, the water-repellent function of the hydrophobic moisture management layer 18 is weak, and moisture that has moved from the anode through the electrolyte membrane is not sufficiently discharged, causing the diffusion overpotential to increase and the cell voltage to rise. If it is greater than 50 μm, the gas will not diffuse easily, causing the diffusion overpotential to increase and the cell voltage to rise.

[0036] Carbon particles are, for example, carbon black. Examples of carbon particles that can be used include Ketjenblack (trademark), acetylene black, Vulcan (trademark), activated carbon, etc.

[0037] Examples of carbon fibers that can be used include single-walled carbon nanotubes, multi-walled carbon nanotubes, and carbon nanofibers.

[0038] As water-repellent materials, fluororesins such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) can be used.

[0039] The average primary particle size of carbon particles and carbon fibers is preferably 10 nm to 300 nm. More preferably, the average primary particle size of carbon particles and carbon fibers is 25 nm to 200 nm, 30 nm to 150 nm, or 30 nm to 100 nm. Carbon fibers have a ratio of long side to short side (long side / short side) of 10 or more. Carbon particles have a ratio of long side to short side of less than 10.

[0040] The average primary particle size of carbon particles is determined from the average of the inscribed and circumscribed diameters of each particle or fiber. The average primary particle size of carbon fibers is determined from the diameter of the carbon fibers. It is preferable to observe the cross-section at half the thickness of the hydrophobic moisture control layer 18 using SEM.

[0041] An intermediate layer (not shown) may be provided between the second diffusion layer 14 and the hydrophobic moisture management layer 18, or between the hydrophobic moisture management layer 18 and the second catalyst layer 16.

[0042] The electrolyte membrane 20 is a proton-conducting membrane. The electrolyte membrane 20 is preferably a fluorinated polymer or an aromatic hydrocarbon polymer having one or more groups selected from the group consisting of sulfonic acid groups, sulfonimide groups, and sulfate groups. A fluorinated polymer having sulfonic acid groups is preferred for the electrolyte membrane 20. Examples of fluorinated polymers having sulfonic acid groups include Nafion (trademark, manufactured by DuPont), Flemion (trademark, manufactured by Asahi Kasei Corporation), Celemion (trademark, manufactured by Asahi Kasei Corporation), Aquivion (trademark, manufactured by Solvay Specialty Polymers), or Aciplex (trademark, manufactured by Asahi Glass Co., Ltd.).

[0043] The thickness of the electrolyte membrane 20 can be appropriately determined considering the characteristics of the membrane, such as its permeability and durability. From the viewpoint of strength, solubility, and output characteristics of the membrane electrode assembly, the thickness of the electrolyte membrane 20 is preferably 20 [μm] to 500 [μm], more preferably 50 [μm] to 300 [μm], and even more preferably 80 [μm] to 200 [μm].

[0044] The electrolyte membrane 20 preferably includes a noble metal region on the side of the first electrode 2. The noble metal region contains noble metal particles. The noble metal region is preferably located on the surface of the electrolyte membrane 20. The noble metal region is preferably composed of a single region, but may be composed of multiple separate regions.

[0045] The precious metal particles are preferably one or more precious metal particles selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru. The precious metal particles may also include alloy particles 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 one precious metal particle selected from the group consisting of Pt, Re, Rh, Ir, Pd, and Ru. Pt particles are preferred for the precious metal particles. Re particles are preferred for the precious metal particles. Rh particles are preferred for the precious metal particles. Ir particles are preferred for the precious metal particles. Pd particles are preferred for the precious metal particles. Ru particles are preferred for the precious metal particles.

[0046] The precious metal particles are generated on the side of the second electrode 12 and oxidize the hydrogen passing through the electrolyte membrane 20. The precious metal particles can suppress hydrogen leakage. Because the precious metal particles are present on the side of the first electrode 2, they are less likely to oxidize the hydrogen discharged from the cathode side. Note that the region where the precious metal particles are present may also be provided in the electrolyte membrane 20 on the side of the second electrode 12.

[0047] Next, the effects and advantages of this embodiment will be described.

[0048] Let's consider the case where the second electrode 12 is used for hydrogen generation. This is, for example, when the membrane electrode assembly 100 is used in a water electrolysis device. Specifically, protons, oxygen, and electrons are generated from water at the first electrode 2. At the second electrode 12, the protons and electrons generated at the first electrode 2 react to produce hydrogen. Here, the second catalyst layer 16 of the second electrode 12 includes a porous catalyst layer containing a porous noble metal or a sheet-like noble metal.

[0049] In this case, when hydrogen gas is generated from the second electrode 12, the interface between the electrolyte membrane 20 and the second catalyst layer 16 may delaminate. When the interface between the electrolyte membrane 20 and the second catalyst layer 16 delaminates, there is a problem in that the electrical resistance of the membrane electrode assembly 100 increases significantly. This is thought to be due to the weak strength of the catalyst layer when the second catalyst layer 16 is a porous catalyst layer containing a noble metal porous material or a sheet-like noble metal, because the catalyst is not supported on a carrier.

[0050] Therefore, in the membrane electrode assembly 100 of this embodiment, the second electrode 12 is provided between the second catalyst layer 16 and the second diffusion layer 14, and has a hydrophobic moisture management layer 18 containing carbon particles and carbon fibers in an amount of 1 wt% to 20 wt% of the weight of the second diffusion layer 14.

[0051] According to this, the introduction of carbon fibers with an appropriate weight improves hydrogen gas permeability. This suppresses the delamination of the electrolyte membrane 20 and the second catalyst layer 16.

[0052] The film electrode assembly of this embodiment makes it possible to provide a highly reliable film electrode assembly.

[0053] (Second Embodiment) The electrochemical cell of this embodiment is an electrochemical cell comprising the membrane electrode assembly of the first embodiment. Here, descriptions that overlap with those of the first embodiment are omitted.

[0054] Figure 3 shows a schematic cross-sectional view of the electrochemical cell 200 of this 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 other substances besides water.

[0055] The electrochemical cell 200 of this embodiment comprises a membrane electrode assembly 100, a separator 23, a separator 24, a seal 80, and a seal 82.

[0056] For example, water is supplied to the first electrode 2. Protons, oxygen, and electrons are generated from the water at the first electrode 2. At the second electrode 12, the protons and electrons generated at the first electrode 2 react to produce hydrogen. Either or both of the generated hydrogen and oxygen can be used as fuel for a fuel cell, for example. The membrane electrode assembly 100 is tightened in the Z and -Z directions using separators 23 and 24.

[0057] According to the electrochemical cell 200 of this embodiment, it becomes possible to obtain a highly reliable electrochemical cell 200.

[0058] (Third embodiment) The stack of this embodiment is a stack comprising the film electrode assembly 100 of the first embodiment. Here, descriptions that overlap with the first and second embodiments are omitted.

[0059] Figure 4 is a schematic cross-sectional view showing the stack 300 of this embodiment. The stack 300 consists of multiple membrane electrode assemblies 100 or electrochemical cells 200 connected in series. Clamping plates 31 and 32 are attached to both ends of the membrane electrode assemblies 100 or electrochemical cells 200.

[0060] According to the stack 300 of this embodiment, it is possible to obtain a stack 300 with a long lifespan.

[0061] (Fourth embodiment) The fourth embodiment relates to an electrolytic apparatus. Here, descriptions that overlap with the first to third embodiments are omitted.

[0062] Figure 5 shows a schematic diagram of the electrolytic apparatus 400 of this embodiment. The electrolytic apparatus 400 is, for example, a hydrogen generator. The electrolytic apparatus 400 comprises an electrochemical cell 200 or a stack 300. The electrolytic apparatus 400 is, for example, an electrolytic apparatus for water electrolysis. In the case of an electrolytic apparatus that generates hydrogen from ammonia, for example, it is preferable to use an apparatus with a different configuration using a membrane electrode assembly 100.

[0063] A power supply 41 is attached to the stack 300. Voltage is applied to the stack 300 by the power supply 41. A gas-liquid separator 42 and a mixing tank 43 are connected to the anode side of the stack 300 to separate the generated gas from unreacted water. Water is supplied to the mixing tank 43 by a pump 46 from an ion-exchange water production device 44. The water is then mixed in the mixing tank 43 through a check valve 47 from the gas-liquid separator 42 and circulated back to the anode.

[0064] The oxygen generated at the anode becomes oxygen gas after passing through the gas-liquid separator 42. Meanwhile, high-purity hydrogen is produced from the cathode using a hydrogen purification device 49 connected to the gas-liquid separator 48. Impurities are discharged through a path with a valve 50 connected to the hydrogen purification device 49. To stably control the operating temperature, heating of the stack and mixing tank, as well as control of the current density during thermal decomposition, can be performed.

[0065] According to the electrolytic device 400 of this embodiment, it is possible to obtain an electrolytic device 400 with a long lifespan. (Examples)

[0066] The following describes some examples.

[0067] Fabrication of the anode (first electrode 2) A Ti nonwoven fabric substrate measuring 25 cm x 25 cm and 200 μm thick was prepared as a diffusion layer plate material 90. Nickel and iridium were sputtered onto this diffusion layer plate material 90 to form a sheet layer. Subsequently, only nickel was sputtered to form a gap layer. This process of forming the sheet layer and gap layer was repeated 40 times until the Ir per unit area was 0.2 mg / cm². 2 A layered structure was obtained so that [the structure was as shown]. Subsequently, a catalyst structure (first catalyst layer 6) was obtained by washing with sulfuric acid to remove nickel. This resulted in the first electrode 2.

[0068] Cathode (second electrode 12) fabrication A carbon paper Toray060 (manufactured by Toray Industries, Inc.) with a carbon layer measuring 25 cm x 25 cm and a thickness of 190 μm was prepared as the second diffusion layer 14. On the second diffusion layer 14, a slurry was applied to the carbon paper, mixed with Cabot Vulcan XC 72 (average primary particle size 40 nm) as carbon particles, GSI Creos' Calber as carbon fiber, and Teflon® PTFE dispersion as a water repellent. This slurry was then fired at 350°C for one hour to form a hydrophobic moisture control layer 18. Next, nickel and platinum were sputtered onto the hydrophobic moisture control layer 18 to form a sheet layer. Subsequently, only nickel was sputtered to form a gap layer. This process of forming the sheet layer and gap layer was repeated 10 times to obtain a laminated structure with a Pt content of 0.1 mg / cm² per unit area. Subsequently, a catalyst structure (second catalyst layer 16) was obtained by washing with sulfuric acid to remove nickel. This resulted in obtaining the second electrode 12.

[0069] Preparation of electrolyte membrane 20 A 30cm x 30cm Chemours Nafion 115 film was used as the electrolyte membrane 20. A solution of tetraammineplatinum diluted to 11 wt% with water was sprayed onto the membrane. The Nafion 115 film was masked with tape before spraying. After 10 minutes from spraying, the membrane was rinsed with pure water, and finally, the membrane was boiled in 10 wt% nitric acid at 80°C for 1 hour to obtain an electrolyte membrane 20 impregnated with Pt particles.

[0070] Next, the first electrode 2, the second electrode 12, and the electrolyte membrane 20 were placed in a hot press apparatus at 160°C and 20 kg / cm³. 2 A 3-minute press was performed at 25°C, 20 kg / cm³. Afterwards, the material was heated to 25°C and 20 kg / cm³. 2 Press cooling was performed for 3 minutes. This resulted in obtaining the film electrode assembly 100.

[0071] Next, the measurement temperature was 80°C and the current density was 2 A / cm². 2The membrane electrode assembly 100 was subjected to steady-state operation of water electrolysis. Ultrapure water was supplied to the anode at a flow rate of 0.05 [L / min]. The cell voltage (V1) was measured after 24 hours of operation. The voltage rise rate (V1) / (VC) was calculated by comparing it with the cell voltage (VC) before evaluation.

[0072] [Table 1]

[0073] As shown in Table 1, the voltage rise rates for the film electrode assemblies of Examples 1 to 10 were all good, at less than 1.5.

[0074] In contrast, the voltage rise rate in the membrane electrode assembly of Comparative Example 1 was too high at 6.23. In the membrane electrode assembly of Comparative Example 1, the amount of carbon fibers in the hydrophobic moisture control layer was too low at 0.5 wt%, resulting in insufficient gas permeability. Consequently, delamination occurred between the second catalyst layer 16 and the electrolyte membrane 20.

[0075] Furthermore, the voltage rise rate in the film electrode assembly of Comparative Example 2 was too high at 7.14. It is presumed that the performance degradation occurred because the amount of carbon fibers in the hydrophobic moisture management layer of the film electrode assembly of Comparative Example 2 was too high at 23 wt%, which increased the porosity of the hydrophobic moisture management layer and reduced conductivity.

[0076] In particular, in Examples 1, 2, 3, 4, 5, 7, and 8, in which a porous catalyst layer was used for the first catalyst layer 6 and the film thickness of the hydrophobic moisture control layer 18 was 10 μm or more and 50 μm or less, a low voltage rise rate of less than 1.3 was obtained.

[0077] While several embodiments and examples of the present invention have been described, these embodiments and examples are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

[0078] Furthermore, the above embodiments can be summarized in the following technical proposal. Technical proposal 1 The first diffusion layer and The first catalyst layer, A first electrode having, The second diffusion layer, A second catalyst layer comprising a porous catalyst layer containing a porous noble metal or a sheet-like noble metal, A hydrophobic moisture control layer is provided between the second catalyst layer and the second diffusion layer, and includes carbon particles and carbon fibers in an amount of 1 wt% to 20 wt% of the weight of the second diffusion layer. It has a second electrode that generates hydrogen, An electrolyte membrane provided between the first electrode and the second electrode, wherein the first catalyst layer is provided between the first diffusion layer and the electrolyte membrane, and the second catalyst layer is provided between the second diffusion layer and the electrolyte membrane, A membrane electrode assembly comprising the above components. Technical proposal 2 The first catalyst layer is a film electrode assembly according to Technical Proposal 1, comprising a porous catalyst layer containing a noble metal porous body or a sheet-like noble metal. Technical proposal 3 The membrane electrode assembly according to Technical Proposal 1, wherein the film thickness of the hydrophobic moisture control layer is 10 μm or more and 50 μm or more. Technical proposal 4 An electrochemical cell using a membrane electrode assembly described in any one of Technical Proposals 1 to 3. Technical proposal 5 A stack using a membrane electrode assembly described in any one of Technical Proposals 1 to 3. Technical proposal 6 An electrolytic apparatus using a membrane electrode assembly described in any one of Technical Proposals 1 to 3. [Explanation of symbols]

[0079] 1: Membrane electrode assembly 2 :1st electrode 4: First diffusion layer 6: 1st catalyst layer 12:Second electrode 14: Second diffusion layer 16:Second catalyst layer 18: Hydrophobic moisture management layer 20: Electrolyte membrane 21: Conductive materials 23: Separator 24: Separator 31: Clamping plate 32: Tightening version 41:Power supply 42: Gas-liquid separation device 43: Mixing tank 44: Ion-exchanged water production device 46: Pump 47: Check valve 48: Gas-liquid separation device 49: Hydrogen purification equipment 50: Valve 80: Seal 82: Seal 90: Diffusion layer plate material 100: Membrane electrode assembly 200: Electrochemical cell 300: Stack 400: Electrolyzer

Claims

1. The first diffusion layer, A first catalyst layer comprising a porous catalyst layer containing a porous noble metal or a sheet-like noble metal, A first electrode having, The second diffusion layer, A second catalyst layer comprising a porous catalyst layer containing a porous noble metal or a sheet-like noble metal, A hydrophobic moisture control layer is provided between the second catalyst layer and the second diffusion layer, comprising carbon particles, carbon fibers in an amount of 1 wt% to 20 wt% of the weight of the second diffusion layer, and a water-repellent material, with a film thickness of 10 μm to 50 μm. It has a second electrode that generates hydrogen, An electrolyte membrane provided between the first electrode and the second electrode, wherein the first catalyst layer is provided between the first diffusion layer and the electrolyte membrane, and the second catalyst layer is provided between the second diffusion layer and the electrolyte membrane, A membrane electrode assembly comprising the above components.

2. An electrochemical cell using the membrane electrode assembly described in claim 1.

3. A stack using the membrane electrode assembly described in claim 1.

4. An electrolytic apparatus using the membrane electrode assembly described in claim 1.

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