JP2019167619A - Laminated electrolyte film, film electrode composite, water electrolysis cell, stack, water electrolysis apparatus, and hydrogen utilization system - Google Patents

Abstract

To provide a laminated electrolyte film exhibiting low gas-crossover and low film resistance in water electrolysis.SOLUTION: Provided is a laminated electrolyte film comprising: a first electrolyte film 1; a second electrolyte film 2; and a nano sheet laminated catalyst layer 3 provided between the first electrolyte film 1 and the second electrolyte film 2, and including a laminated structure in which a plurality of nano sheet-like catalysts are laminated with intervals.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a laminated electrolyte membrane, a membrane electrode assembly, a water electrolysis cell, a stack, a water electrolysis apparatus, and a hydrogen utilization system.

At present, a fuel cell is attracting attention and developed as a clean power generation system capable of reducing the environmental load. In particular, they are starting to be used in various fields such as home power supply and in-vehicle use. On the other hand, in order to prevent global warming, reduction of CO ₂ emission labor is indispensable, and the use of regenerative energy such as solar cells and wind power generators is actively used as clean energy that does not emit CO _2. It is done. Since these renewable energies are greatly affected by the energy that can be produced by the weather or the like, they are being studied as a stable power supply system by storing electricity by a secondary battery or converting it to chemical energy by compound synthesis.

  In recent years, a “hydrogen society” has been proposed in a clean energy supply system that produces hydrogen from renewable energy and generates power with a fuel cell. For these reasons, hydrogen is attracting attention in the conversion from electrical energy to compounds (chemical energy). Alkaline water electrolysis and polymer electrolyte membrane (PEM) type water electrolysis are available as hydrogen production methods. There is a solid oxide electrolysis cell (SOEC), and recently, PEM type water electrolysis has been actively studied as a highly efficient water electrolysis.

  For example, in a PEM type water electrolysis apparatus, a platinum group metal is bonded to both sides of a solid polymer electrolyte membrane (fluororesin-based cation exchange membrane) so as to be integrated with the membrane, one of which is an anode and the other is a cathode. To do. When a DC voltage is applied between the two electrodes while supplying water to the anode side, oxygen gas is generated from the anode and hydrogen gas is generated from the cathode, and the polymer electrolyte membrane functions as a diaphragm. The generated hydrogen gas and oxygen gas Can be taken out separately.

  In order to improve the performance of PEM type water electrolysis, it is only necessary to improve the proton conductivity of the electrolyte membrane, and it is necessary to reduce the membrane resistance. However, if the electrolyte membrane is thinned to improve proton conductivity, the membrane resistance is reduced. However, the oxygen crossover from the anode to the cathode and the hydrogen crossover from the cathode to the anode are greatly increased. When the crossover increases, the electromotive force decreases due to reaction with the electrode. Therefore, an electrolyte membrane with low crossover and low membrane resistance is required.

JP-A-6-103992 Japanese Patent Laid-Open No. 7-90111 JP 2005-530330 A Special table 2016-505193 gazette

M. Watanabe et al. J. Electrochem. Soc., 143, No. 12, 3847-3852 (1996)

  Embodiments of the present invention provide a laminated electrolyte membrane with low gas crossover in water electrolysis.

  In order to achieve the above object, a multilayer electrolyte membrane according to an embodiment is provided between a first electrolyte membrane, a second electrolyte membrane, a first electrolyte membrane, and a second electrolyte membrane, and a plurality of nanosheet catalysts are provided. A nanosheet laminated catalyst layer including a laminated structure laminated with a gap.

1 is a cross-sectional view of a multilayer electrolyte membrane according to Embodiment 1. FIG. The photograph which shows the structure of a nanosheet laminated catalyst layer. The figure which shows the manufacturing method of a nanosheet laminated catalyst layer. Sectional drawing of the membrane electrode assembly (Membrane Electrode Assembly: MEA) of Embodiment 2. FIG. Sectional drawing of the cell for water electrolysis of Embodiment 3. FIG. FIG. 5 is a diagram illustrating a stack according to a fourth embodiment. FIG. 6 is a diagram illustrating a water electrolysis device according to a fifth embodiment. The figure which shows the hydrogen utilization system of Embodiment 6. FIG. The figure which shows the hydrogen utilization system of Embodiment 7. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the same members and the like are denoted by the same reference numerals, and the description of the members and the like once described is omitted as appropriate.

(Embodiment 1)
FIG. 1 shows a cross-sectional view of the multilayer electrolyte membrane 100 of the first embodiment.
The laminated electrolyte membrane 100 of the first embodiment includes an electrolyte membrane 1 (also referred to as a first electrolyte membrane), a nanosheet laminated catalyst layer 3, a transfer layer 4, and an electrolyte membrane 2 (also referred to as a second electrolyte membrane) sequentially. Laminated. As the electrolyte membranes 1 and 2 used in the multilayer electrolyte membrane 100, a pearl fluorosulfonic acid electrolyte membrane or a hydrocarbon sulfonic acid electrolyte membrane can be used. When the multilayer electrolyte membrane 100 of the embodiment is used as an electrolyte membrane for water electrolysis, it is preferable in that the membrane resistance of the multilayer electrolyte membrane is low and the crossover is low.

  A laminated electrolyte membrane 100 in FIG. 1 is provided between the electrolyte membranes 1 and 2, the electrolyte membrane 1 and the electrolyte membrane 2, and includes a nanosheet laminated catalyst layer 3 including a catalyst and voids, and an electrolyte membrane 2 and a nanosheet laminated catalyst layer 3. And a transfer layer 4 for bonding the electrolyte membrane 2 and the nanosheet laminated catalyst layer 3 to each other. The electrolyte membrane 1 and the electrolyte membrane 2 of this laminated electrolyte membrane may be the same electrolyte or different.

  The thickness of the multilayer electrolyte membrane 100 is preferably 20 μm or more and 400 μm or less. Here, the “thickness” indicates an average thickness in the stacking direction. The average thickness indicates an average thickness calculated using a cross-sectional view observed with a scanning electron microscope (SEM). The “stacking direction” indicates the direction from the electrolyte membrane 1 to the electrolyte membrane 2 with the shortest distance. If the thickness of the multilayer electrolyte membrane 100 is less than 20 μm, the membrane is thin, which is not preferable because the mechanical strength and durability are lowered. If the thickness of the multilayer electrolyte membrane 100 exceeds 400 μm, the membrane resistance Is not preferable because the efficiency of water electrolysis decreases. For the above reason, the thickness of the multilayer electrolyte membrane 100 is more preferably 25 μm or more and 250 μm or less.

  The electrolyte membranes 1 and 2 are layers that conduct ions (protons) and are electrically insulated. The thicknesses of the electrolyte membranes 1 and 2 are each preferably 1 μm or more and 390 μm or less, and more preferably 2 μm or more and 150 μm or less. As the electrolyte, a pearl fluorosulfonic acid-based electrolyte is preferably used, and the thicknesses of the electrolyte membranes 1 and 2 may be the same or different.

  The pearl fluorosulfonic acid electrolyte is preferably a polymer having an acidic group such as a sulfonic acid group or a sulfonimide group in the fluorine-containing main chain skeleton. Examples of the pearl fluorosulfonic acid electrolyte include Nafion (trademark, manufactured by DuPont), Aquivion (trademark, manufactured by Solvay), Flemion (trademark, manufactured by Asahi Kasei), and Aciplex (trademark, manufactured by Asahi Glass). It is done.

  Furthermore, in order to increase the mechanical strength of these electrolyte membranes, electrolyte membranes reinforced with a porous membrane may be used. Specific examples of the porous membrane include, but are not limited to, PTFE (polytetrafluoroethylene), PEEK (polyetheretherketone), PP (polypropylene), glass fiber nonwoven fabric, and glass paper.

The nanosheet laminated catalyst layer 3 is provided to suppress hydrogen and oxygen crossover. The nanosheet laminated catalyst layer 3 includes a laminated structure composed of a catalyst. The nanosheet laminated catalyst layer 3 is preferably a porous laminated structure spreading in a planar shape. That is, hydrogen and oxygen that have entered the nanosheet laminated catalyst layer 3 are converted to water by a chemical reaction of H ₂ + 1 / 2O ₂ → H ₂ O. The thickness of the nanosheet laminated catalyst layer 3 is preferably 10 nm or more and 2000 nm or less in order to sufficiently suppress the crossover. If the thickness of the nanosheet laminated catalyst layer 3 is less than 10 nm, it is difficult to maintain a laminated structure, and if it exceeds 2000 nm, proton conductivity is lowered, which is not preferable.

  FIG. 2 is a photograph showing the structure of the nanosheet laminated catalyst layer 3. As shown in FIGS. 2A and 2B, the nanosheet laminated catalyst layer 3 is a laminated structure including a carrier-less catalyst having a porous structure and voids. Support-less means that no support is used for the catalyst. FIG. 2A shows a porous structure catalyst, and FIG. 2B shows a laminated structure including the catalyst and voids. As shown in FIG. 2A, when the catalyst has a porous structure, the catalyst itself is sponge-like. As shown in FIG. 2B, in the laminated structure including the catalyst and the voids, the catalyst is formed in a nanosheet shape. Moreover, the nanosheet-like catalyst and voids are alternately laminated in the lamination direction. That is, it can be said that it has a laminated structure in which a plurality of nanosheet-like catalysts are laminated with gaps. In the case of a laminated structure including a catalyst and voids, it is preferable that adjacent nanosheets are partially integrated. This is because proton conduction or hydrogen atom conduction can be made smoother. Moreover, it is because proton conduction or hydrogen atom conduction can be further improved by making the nanosheet of the laminated structure porous as shown in FIG. Further, if porous nanocarbon containing fibrous carbon (FIG. 2 (d)) or nanoceramics is disposed in the void portion, durability is improved.

Here, since the conduction of protons and water becomes smoother, the laminated structure preferably has a structure with a high porosity. The laminated structure has a large number of voids inside. In order to reduce the crossover when the catalyst is a particle, for example, it is necessary to arrange the catalyst particles in a layered form at a high density. However, since the particles arranged in the electrolyte membrane are very small particles of nano size, they are aggregated when arranged at a high density, and the particles exist locally, and H ₂ passes between the particles. It is easy and it is difficult to lower the crossover. Even if the particles can be dispersed at a high density, the proportion of the catalyst particles in the layered region in which the catalyst is disposed becomes very high, and the proton conductivity decreases. Therefore, particulate and non-porous catalyst cannot be arranged in layers in the electrolyte membrane. In other words, the particulate catalyst can arrange the particles in an island shape, but cannot arrange the particles in a layered manner. On the other hand, in the embodiment, the laminated structure becomes like a wall, and the crossover can be lowered. And since a laminated structure contains many space | gap, conduction of proton, water, etc. is smooth, and membrane resistance does not become high.

  From this viewpoint, the pore area ratio of the laminated structure is preferably 50% or more and 90% or less. Furthermore, the pore area ratio of the laminated structure is more preferably 60% or more and 80% or less. The porosity of the laminated structure is the area ratio of the region not in contact with the electrolyte membranes 1 and 2 inside the laminated structure of the nanosheet laminated catalyst layer 3 ([the electrolyte membrane 1 inside the laminated structure of the nanosheet laminated catalyst layer 3 2 is the area of the region not in contact with 2] / [the area of the nanosheet laminated catalyst layer 3]). In addition, when the porous nanocarbon or nanoceramics containing fibrous carbon are arrange | positioned in the space | gap of a laminated structure, the porous nanocarbon or nanoceramics containing fibrous carbon are considered as the space | gap of a laminated structure. Further, if the porosity of the catalyst is within this range, the substance can be sufficiently conducted without reducing the utilization efficiency of the noble metal.

  The area ratio of the region not contacting the electrolyte membranes 1 and 2 in the laminated structure of the nanosheet laminated catalyst layer 3 is the nanosheet laminated in the vertical direction of the cross section of the figure from the imaginary line (dashed line) AA ′ in FIG. A cross section of the catalyst layer 3 is observed with a scanning electron microscope (SEM). Since the nanosheet laminated catalyst layer 3 is thin, when a part of the cross section is the nanosheet laminated catalyst layer 3, only the portion that is the nanosheet laminated catalyst layer 3 is observed. The hole area ratio can be obtained from the contrast of the observation image. Moreover, it can also confirm from the observation image that the nanosheet laminated catalyst layer 3 is not an island-shaped catalyst but has a structure spreading in a planar shape. When water is included in the laminated structure, water is regarded as a void and the area ratio is obtained.

The catalyst used for the nanosheet laminated catalyst layer 3 is not particularly limited as long as it becomes a reaction catalyst for hydrogen and oxygen. For example, Pt or an alloy containing at least Pt and having a composition represented by Pt _u M _1-u is used. desirable. Here, u is 0 <u ≦ 1, and the element M is from Co, Ni, Fe, Mn, Ta, W, Hf, Si, Mo, Ti, Zr, Nb, V, Cr, Al, and Sn. Is at least one selected from the group consisting of This alloy catalyst contains more than 0 atomic% and 90 atomic% or less of Pt, and 10 atomic% or more and less than 100 atomic% of element M. Moreover, 0.01-0.50 mg / cm < ² > is good for the amount of Pt in a catalyst. The 0.02 mg / cm ² or less, the effect of reducing the cross-over is low, the 0.50 mg / cm ² or more, the film resistance increases. When the above metal catalyst is used, high durability can be maintained even with a small amount of use.

  The content of the catalyst is analyzed by using an inductively coupled plasma mass spectrometer (ICP-MS) to analyze the content of elements and the content, and scanning electron microscope / energy dispersive X-ray spectroscopy (Scanning Electron Microscope / By mapping with Energy Dispersive X-ray Spectroscopy (SEM-EDX), the element distribution is observed and analyzed. In addition, it is preferable to use an X-ray diffractometer to identify the oxide.

  A method for producing the nanosheet laminated catalyst layer 3 will be described with reference to FIG. As shown in FIG. 3, a transfer layer 4 is formed on a substrate 5, and Pt or a Pt alloy and a metal that dissolves in acid or alkali are alternately stacked thereon by sputtering, and then dissolved in acid or alkali. The metal to be dissolved is dissolved. After producing the nanosheet laminated catalyst layer 3, the substrate 5 is peeled off and removed.

  The transfer layer 4 is provided for bonding the electrolyte membrane 2 and the nanosheet laminated catalyst layer 3. The transfer layer 4 may be prepared by any method on the substrate 5, and specifically, inorganic nanoparticle-containing dispersion solution, polymer solution, and inorganic nanoparticle containing a binder (polymer). A particle dispersion or the like is applied to a substrate and dried. The thickness of the transfer layer 4 is preferably 0.1 μm or more and 15 μm or less. If the thickness exceeds 15 μm, it is difficult to transmit protons, and the resistance of the multilayer electrolyte membrane 100 is increased. On the other hand, when the thickness is less than 0.1 μm, the catalyst of the nanosheet laminated catalyst layer 3 is also peeled off together with the base material 5 when the base material 5 is peeled off. On the other hand, the polymer and binder to be used may be those that can withstand the subsequent process conditions. Specifically, the pearl fluorosulfonic acid electrolyte (which may be the same as or different from the electrolyte used for the electrolyte membranes 1 and 2), polybenzothiazole (PBT), polybenzoxazole (PBO), polybenzo Examples include, but are not limited to, imidazole (PBI). The transfer layer 4 may be applied by any method as long as it can be applied, and examples thereof include a spin coating method, a blade coating method, an ink jet method, a gravure method, and a spray coating method, but are not limited thereto. The applied film is dried by heating and the temperature is preferably 60 ° C. or higher and lower than 250 ° C. About drying time, it can adjust with the solvent to be used and the film thickness of electrolyte. If the temperature is lower than 60 ° C., the solvent is not sufficiently volatilized, and if it is higher than 250 ° C., the polymer film (binder) may be decomposed.

  The laminated electrolyte membrane 100 is formed by transferring the nanosheet laminated catalyst layer 3 (the transfer layer 4 is simultaneously transferred) onto the electrolyte membrane 1 and then bonding the electrolyte membrane 2 onto the transfer layer 4 or applying an electrolyte solution. The electrolyte membrane 2 is formed and produced.

  The method for applying the electrolyte membrane 2 may be any method that can be applied, and examples thereof include, but are not limited to, spin coating, blade coating, ink jet, gravure, and spray coating. The applied film is dried by heating and the temperature is preferably 60 ° C. or higher and lower than 250 ° C. The drying time can be adjusted by the solvent used and the thickness of the electrolyte membrane. If the temperature is lower than 60 ° C., the solvent is not sufficiently volatilized.

When the transfer layer 4 and the electrolyte membrane 2 are bonded together, temperature and pressure are applied. The electrolyte membrane 2 to be bonded may be sufficiently swollen with water or may be dried. The transfer temperature and the lamination temperature are 80 to 200 ° C, and 120 to 180 ° C is particularly preferable. The pressurization is preferably less than 50 kg / cm ² if performed by a hot press, for example. If it is 50 kg / cm ² or more, the mechanical strength may be lowered. In addition, it can carry out also by the method by a roll as a pressurization heating drying method.

  The substrate 5 can be anything as long as it can withstand the transfer temperature at the time of transfer and is stable to some extent with respect to an aqueous solution of acid and alkali. Specific examples include carbon, polyimide film, polyamide film, PTFE film, and PEN film. It is not done.

  In the multilayer electrolyte membrane 100 of the first embodiment, the nanosheet multilayer catalyst layer 3 is provided between the electrolyte membrane 1 and the electrolyte membrane 2. When the laminated electrolyte membrane 100 is used as an electrolyte membrane for water electrolysis, the nanosheet laminated catalyst layer 3 shields a gas such as hydrogen or oxygen to suppress crossover. Further, since the thickness of the nanosheet laminated catalyst layer 3 is smaller than the thickness of the laminated electrolyte membrane 100, a laminated electrolyte membrane with low membrane resistance that does not inhibit proton conductivity can be obtained. The thickness of the nanosheet laminated catalyst layer 3 relative to the thickness of the laminated electrolyte membrane 100 ([thickness of laminated electrolyte membrane 100] / [thickness of nanosheet laminated catalyst layer 3]) is 0.01 / 1000 or more and 0.5 / It is preferable that it is 1000 or less.

The laminated electrolyte membrane 100 may have a membrane to which an additive for increasing chemical durability is added. Examples of the additive include a radical scavenger and a radical decomposer. For example, an organic phosphorus compound, an aromatic amine compound, a phenol compound, a thioether compound, CeO ₂ , MnO _{2 and the} like can be given as an additive. The radical scavenger or the hydrogen peroxide decomposer may be contained in a proportion of 0% by mass to 10% by mass.

  Instead of the example of FIG. 1, the substrate 5 may be provided instead of the transfer layer 4. For example, in this case, by using glass paper (which may be a porous inorganic material) as the base material 5, it becomes a reinforcing agent for the electrolyte membrane 2 and the transfer layer 4 becomes unnecessary.

  Further, not the electrolyte membrane 2 but the electrolyte membrane 1 may be in contact with the transfer layer 4 regardless of the example of FIG.

(Embodiment 2)
FIG. 4 shows a cross-sectional view of a membrane electrode assembly (MEA) 200 of the second embodiment.

  The membrane electrode assembly 200 of Embodiment 2 includes a first electrode 6, a second electrode 7, and a multilayer electrolyte membrane 100. Use of the membrane electrode assembly 200 for water electrolysis is preferable in that the laminated electrolyte membrane has low membrane resistance and low crossover.

  The first electrode 6 is a cathode. The first electrode 6 includes a first catalyst layer (not shown) containing a catalyst that contacts the electrolyte membrane 1 and electrolyzes water, and a support (not shown) that supports the first catalyst layer. The second electrode 7 is an anode. The second electrode 7 includes a second catalyst layer (not shown) containing a catalyst that contacts the electrolyte membrane 2 and electrolyzes water, and a support (not shown) that supports the second catalyst layer (not shown). Have. In addition, it is desirable that the electrolyte membrane of the electrolyte membrane in contact with the second electrode (anode) 7 is a pearl fluorosulfonic acid electrolyte membrane because chemical durability such as radicals is increased. The first and second catalyst layers may use the same catalyst or different catalysts, and at least one of them is preferably a laminated structure such as the nanosheet laminated catalyst layer 3. When a laminated structure is used, the gas shielding rate of hydrogen or oxygen is further improved, and crossover is reduced. The first and second catalyst layers are composed of a supported catalyst in which a material such as carbon or a conductive oxide is used as a support and a catalyst is supported on the surface thereof. Although the support hardly contributes to the main electrocatalytic reaction, it can control the catalyst material such as an increase in the reaction area of the catalyst material, and can improve the pore structure, electrical conductivity, ion conductivity and the like.

  The catalyst material of the first and second catalyst layers includes at least one selected from the group consisting of noble metal elements such as Pt, Ru, Rh, Os, Ir, Pd and Au. Such a catalyst material is excellent in catalytic activity, conductivity and stability. The noble metal may be used as an oxide, and may be a complex oxide or a mixed oxide containing two or more metals.

  The optimum noble metal element can be appropriately selected according to the reaction in which the membrane electrode assembly 200 is used.

For example, when a hydrogen generation reaction is required as a cathode for water electrolysis, a catalyst having a composition represented by Pt _u M _1-u is desirable. Here, u is 0 <u ≦ 1, and the element M is from Co, Ni, Fe, Mn, Ta, W, Hf, Si, Mo, Ti, Zr, Nb, V, Cr, Al, and Sn. Is at least one selected from the group consisting of This catalyst contains more than 0 atomic% and 90 atomic% or less of Pt, and 10 atomic% or more and less than 100 atomic% of element M.

On the other hand, when a water oxidation reaction (oxygen generation reaction) is required as an anode for water electrolysis, an oxide catalyst containing at least one of Ir, an oxide catalyst containing at least one of Ru and Ir, Pt A metal catalyst containing any one of Ru and Ir and an alloy catalyst containing any one of Pt, Ru and Ir are desirable. Examples of the oxide catalyst include a catalyst having a composition represented by Ir _z M _1-z O. Here, z is 0.5 <z, and the element M is Co, Ni, Fe, Mn, Ta, W, Hf, Si, Mo, Ti, Zr, Nb, V, Cr, Sr, and Sn. It is at least one selected from the group consisting of: The oxide catalyst contains an element M that is 50 atomic% or more and of which 0 atomic% or more and less than 50% atom. Specific examples of the oxide catalyst include at least one selected from the group consisting of IrO ₂ , RuO ₂ , IrRu _x O _y , IrNi _x O _y , IrSr _x O _y and IrRu _x Ni _y O _z , Examples of the anode catalyst of the membrane electrode assembly 200 of the embodiment include, but are not limited to, an oxide catalyst that includes one or more metals of Ru and Ir, and optionally one or more elements M. Not.

  The membrane electrode assembly 200 is produced by bonding the first electrode 6 and the second electrode 7 to the multilayer electrolyte membrane 100. Generally, the first catalyst layer and the laminated electrolyte membrane 100 are bonded by heating and pressurizing. In this case, when the support for forming the first and second catalyst layers is a gas diffusion layer, stacking is performed as shown in FIG. 4 with the multilayer electrolyte membrane 100 sandwiched between the support including the first and second catalyst layers, The membrane electrode assembly 200 is obtained by bonding.

  When the support for forming the first and second catalyst layers is a transfer substrate, first, the first and second catalyst layers are transferred from the transfer substrate to the laminated electrolyte membrane 100, and the first and second catalyst layers are then transferred. Is transferred to the electrolyte membrane 100 to produce a membrane-coated membrane assembly (Catalyst Coated Membrane; CCM). The CCM is laminated as shown in FIG. 4 with two gas diffusion supports sandwiched, and heated and pressurized. The membrane electrode assembly 200 is obtained by bonding together. Alternatively, after transferring at least one of the first and second catalyst layers to the electrolyte membrane 100, a gas diffusion layer may be disposed thereon. These are laminated as shown in FIG. 4 and bonded by heating and pressing to obtain a membrane electrode assembly 200.

  In the membrane electrode assembly 200 according to the embodiment, the electrolyte membrane 1 and the first electrode 6, the electrolyte membrane 2 and the second electrode 7 are combined, and the nanosheet laminated catalyst layer 3 and the electrodes 6 and 7 are separated from each other. This is because the electrolyte membranes 1 and 2 have higher connectivity with the electrodes 6 and 7 than the nanosheet laminated catalyst layer 3. When membrane electrode assembly 200 is used for water electrolysis, it is difficult to peel off in water.

(Embodiment 3)
FIG. 5 shows a cross-sectional view of the water electrolysis cell 300 of the third embodiment.
As shown in FIG. 5, the water electrolysis cell 300 of Embodiment 3 includes a membrane electrode assembly 200, a first electrode (cathode) 6, a second electrode (anode) 7, a laminated electrolyte membrane 100, and a cathode power supply. It has a body 10, a separator 11, an anode power supply body 12, a separator 13, a gasket (seal) 8, and a gasket (seal) 9. The cathode power supply body 10 and the anode power supply body 12 may be anything that allows gas or water to pass through. The power feeders 10 and 12 may be integrated with the separators 11 and 13. Specifically, the separator has a flow path through which water or gas flows, or has a porous body, but is not limited thereto. In the cell 300 for water electrolysis using the multilayer electrolyte membrane 100 of the embodiment, when the membrane electrode assembly 200 is used for water electrolysis, the membrane resistance of the multilayer electrolyte membrane is low and the crossover is low. This is preferable because it can be performed.

  In the water electrolysis cell 300 of FIG. 5, an electrode (not shown) is connected to the cathode power supply 6 and the anode power supply 12, and a reaction occurs between the cathode and the anode. Water is supplied to the anode, and water is decomposed into protons, oxygen, and electrons at the anode electrode. The electrode support and the power feeding body are porous bodies, and the porous body functions as a flow path plate. The generated water and unreacted water are discharged, and protons and electrons are used for the cathode reaction. In the cathode reaction, protons and electrons react to generate hydrogen. Either or both of the generated hydrogen and oxygen are used as a fuel for a fuel cell, for example. The membrane electrode assembly 200 is held by the separators 11 and 13, and the airtightness is maintained by the gaskets (seal) 8 and 9.

(Embodiment 4)
FIG. 6 is a diagram illustrating a stack according to the fourth embodiment.
A stack 400 of Embodiment 4 shown in FIG. 6 is obtained by connecting a plurality of membrane electrode assemblies 200 or water electrolysis cells 300 in series. Fastening plates 14 and 15 are attached to both ends of the water electrolysis cell.

  Since the voltage from one MEA 200 or water electrolysis cell 300 is low, a high voltage can be obtained by forming a stack 400 in which a plurality of MEAs 200 or water electrolysis cells 300 are connected in series. Since the amount of hydrogen produced in the water electrolysis cell 300 composed of one MEA 200 is small, a large amount of hydrogen can be obtained by configuring a stack 400 in which a plurality of water electrolysis cells 300 are connected in series.

(Embodiment 5)
FIG. 7 is a diagram illustrating a water electrolysis device according to a fifth embodiment.
In the fifth embodiment, a stack 400 is used for the water electrolysis apparatus 500. As shown in FIG. 7, a water electrolysis stack 400 is formed by stacking water electrolysis single cells in series. A power source 21 is attached to the water electrolysis stack 400, and a voltage is applied between the anode and the cathode. The anode side of the water electrolysis stack 400 is connected to a gas-liquid separation device 18 and a mixing tank 17 for separating the generated gas and unreacted water. Liquid is fed from the device 16 by the pump 22, mixed from the gas-liquid separator 18 through the check valve 23, mixed in the mixing tank 17 and circulated to the anode. Oxygen generated at the anode passes through the gas-liquid separator 18 to obtain oxygen gas. On the other hand, on the cathode side, a hydrogen purifier 19 is connected continuously to the gas-liquid separator 20 to obtain high purity hydrogen. Impurities are discharged through a path having a valve 24 connected to the hydrogen purifier 19. In order to stably control the operating temperature, it is possible to control the heating of the stack and the mixing tank, the current density during pyrolysis, and the like.

(Embodiment 6)
FIG. 10 is a diagram illustrating a hydrogen utilization system 600 according to the sixth embodiment.
In the sixth embodiment, a water electrolysis device 500 is used. As shown in FIG. 10, power from a power source 61 such as solar power generation or wind power generation is converted into hydrogen gas by a water electrolysis device 500. Further, the hydrogen gas is directly supplied to the hydrogen power generation device 62 via the hydrogen power generation device 62 or the hydrogen gas tank 63. The hydrogen power generation device 62 is converted into electricity by reacting with air and can be used as electric power for the driving device 64. Examples of the hydrogen power generation device 62 include a hydrogen gas turbine and a fuel cell, and examples of the drive device 64 include a car, a household appliance, and an industrial device. By using the electrode of the present invention, it is possible to construct the hydrogen utilization system of Embodiment 6 with low power consumption and high durability.

(Embodiment 7)
FIG. 11 is a diagram illustrating a hydrogen utilization system 700 according to the seventh embodiment.
In Embodiment 7, a reversible fuel cell (Unitized Regenerative Fuel Cell: URFC) in which hydrogen production by water electrolysis and power generation are switched is installed. A water electrolysis stack 400 is used for the reversible fuel cell. As shown in FIG. 8, a water electrolysis stack 400 is formed by stacking water electrolysis cells 300 in series. A power source 71 such as solar power generation or wind power generation is attached to the water electrolysis stack 400, and a voltage is applied between the anode and cathode in the hydrogen production mode. The anode side of the water electrolysis stack 400 is connected to a gas-liquid separator 72 and a mixing tank 73a for separating generated gas and unreacted water. Liquid is fed from the device 74 by the pump 75a, mixed from the gas-liquid separation device 72 through the check valve 75b, mixed by the mixing tank 73a, and circulated to the anode. Oxygen generated at the anode is passed through a gas-liquid separator 72 to obtain oxygen gas. On the other hand, on the cathode side, a hydrogen purifier 77 is connected continuously to the gas-liquid separator 76 to obtain high purity hydrogen. High purity hydrogen gas is stored in the hydrogen gas tank 73b. Impurities are discharged through a path having a valve 78 connected to the gas-liquid separator 76.

  On the other hand, in the power generation mode, high-purity hydrogen stored in the hydrogen tank 73b is supplied to the water electrolysis stack 400 and reacts with external air, so that it is converted into electricity by the fuel cell reaction and used as power for the drive device 79. be able to. Examples of the driving device 79 include cars, home appliances, and industrial devices. By using the electrode of the present invention, it is possible to construct the hydrogen utilization system of Embodiment 7 that is small and compact, consumes less power, and has high durability.

Examples will be described in detail below.
(Examples 1-16 and Comparative Examples 1-4)
(Adjustment of coating solution for transfer)
Ethanol is added to a predetermined amount of fluorine-based electrolyte dispersion (20% nafion dispersion, manufactured by Du Pont) in a polypot, a predetermined amount of binder and nano inorganic particles are added, and 40 zirconia balls (diameter 5 mm) are added, The coating solution for transfer layer 4 was prepared by dispersing for 90 minutes with a paint shaker. Table 1 shows S1-7 as the composition of the prepared coating solution.

(Preparation of 5% WO ₃ / TiO ₂ super strong oxide)
An aqueous solution in which tungsten oxide (manufactured by Wako Pure Chemical Industries) WO ₃ was dissolved in a hot concentrated aqueous ammonia solution (manufactured by Wako Pure Chemical Industries, 15% aqueous solution) was prepared. This aqueous solution was mixed with a dispersion in which titanium oxide TiO ₂ (manufactured by Showa Denko, Super Titania F-6) was dispersed in water. This was evaporated to dryness at 80 ° C., and ammonium tungstate was supported on TiO ₂ . The obtained precursor was dried at 100 ° C. for 6 hours and then calcined at 700 ° C. for 4 hours to thermally decompose ammonium tungstate to obtain WO ₃ / TiO ₂ . The composition of WO ₃ / TiO ₂ was 5/95 by weight.

  Apply 15.0 g of the transfer layer 4 solution prepared above onto a Kapton film (50 μm) by spraying the composite membrane dispersion (set a drum Kapton film with a diameter of 15 cm and a width of 10 cm, rotate the drum at about 550 rpm, The spray portion was reciprocated at an interval of 10 cm, and dried at 60 ° C. for 10 minutes, and then dried at 160 ° C. for 10 minutes to produce a transfer layer 4.

(Preparation of transfer layer 4 catalyst)
On the transfer layer 4, various metal catalysts of Pt, PtCo, PtNi, PtCoNi and a gap agent were alternately sputtered, etched with an acid, washed with water, and dried by heating. Table 2 shows the amounts of platinum loading in the Pt and Pt alloy catalysts.

(Preparation of laminated electrolyte membrane 100 Preparation M1-15)
The electrolyte membrane 1 is placed on the transfer layer 4 produced as described above, transferred with a hot press (160 ° C., 5 minutes, 12.5 kg / cm ² ), peeled off Kapton, transferred the nanosheet laminated catalyst layer 3, and then the electrolyte. The membrane 2 was placed on the transfer layer 4 and hot-pressed under the same conditions to produce multilayer electrolyte membranes M1 to M14.

However, the laminated electrolyte membrane M15 was prepared by applying the liquid in 1% nafion after transferring the nanosheet laminated catalyst layer 3 and drying at 60 ° C. for 10 minutes, followed by hot pressing (160 ° C., 5 minutes, 12.5 kg / cm ² ). The electrolyte membrane 2 was 5 μm. The detailed configuration is shown in Table 2.

(Preparation of Multilayer Electrolyte Membrane 100 Preparation of M16) PtCo metal catalyst and interstitial agent were alternately sputtered onto glass fiber filter paper (GC-50, 190 μm, manufactured by ADVANTEC), then etched with acid, washed with water and dried by heating. did. Table 2 shows the amount of platinum loading in the PtCo catalyst.

The glass fiber filter paper with the above catalyst layer (with the catalyst layer facing up) was fixed on a PTFE film, and a solution obtained by diluting 25% by weight Aquivion (d72-25BS) aqueous solution to 5% with ethanol was sufficiently applied at 60 ° C. For 10 minutes. Then, it pressed for 5 minutes at 160 degreeC and the pressure of 10 kg / cm < ² > with the hot press. After cooling, the film was removed from the PTFE film to obtain a film having a thickness of 200 μm. On the PTFE film side at the time of forming this membrane, a solution of 5 wt% Aquivion (d72-25BS) aqueous solution diluted to 5% with ethanol was applied to prepare a membrane of about 1 μm, and an electrolyte membrane M16 was produced.

(Production of composite electrolyte membranes C1 to C3)
(Comparative Example 1 composite electrolyte membrane C-1)
First, platinum black (manufactured by TKK) 0.625 g and water 10.0 g were added to a 50 ml polypot and stirred well, then ethanol 7.50 g and IPA 7.50 g were added, and nafion solution 9.06 g was added. Thereto, 40 zirconia balls (diameter 5 mm) were added and dispersed for 90 minutes with a paint shaker to prepare a catalyst coating solution. The catalyst dispersion is dried on a PTFE film (100 μm) set on a drum (diameter 15 cm, width 10 cm) with a dryer, and the drum is rotated at about 550 rpm, and the spray portion is reciprocated at intervals of 10 cm. Then, after drying at 60 ° C. for 10 minutes on a hot plate, it was further dried at 130 ° C. for 10 minutes to prepare a catalyst transfer layer. The catalyst layer had a thickness of about 10 μm and a Pt-loading amount of 2.0 mg / cm ² . On this catalyst transfer layer, it was placed on nafion 115, transferred with a hot press (160 ° C., 5 minutes, 12.5 kg / cm ² ), PTFE was peeled off, and a composite electrolyte membrane C-1 was produced.

(Comparative Example 2 composite electrolyte membrane C-2)
After Nafion 115 was sufficiently swollen with water, one side was masked with a PTFE film, immersed in a 0.03M Pt (NH ₃ ) ₄ Cl ₂ aqueous solution for 2 minutes, subjected to cation exchange, washed with water, 1 Reduction was performed by immersing in a 3% NaBH aqueous solution for 3 hours. After washing with water, it is immersed in 10% nitric acid at 60 to 70 ° C. for about 1 hour, washed with ion exchange water, further immersed in 10% nitric acid at 60 to 70 ° C. for about 1 hour, washed with ion exchange water and washed with Pt. An electrolyte membrane C-2 was prepared. The amount of Pt-loading in the membrane was 0.24 mg / cm ² .

(Comparative Example 3 Composite Electrolyte Membrane C-3)
An electrolyte membrane composited with Pt was produced using the electrolyte membrane nafion 212 in the same manner as in Comparative Example 2. In a state where this membrane is sufficiently swollen with water, nafion 212 is hot-pressed with a hot press (160 ° C., 5 minutes, 12.5 kg / cm ² ) on the surface that is not combined with Pt, and composite electrolyte membrane C-3 is obtained. Produced. The amount of Pt-loading was 0.24 mg / cm ² .

(Preparation of anode electrode)
For the anode electrode, IrNi _x O _y and a gap agent were alternately sputtered on a 200 μm porous titanium body by reactive sputtering to produce a laminated structure, etched by acid treatment, dried by heating, and heated at 435 ° C. It was made by heat treatment for a period of time. The IrNi _x O _y catalyst layer has an Ir content of 0.12 mg / cm ² (22 layers).

(Preparation of cathode electrode)
PtCo and a gap agent were alternately sputtered onto a carpon pepper with a cathode electrode MPL (microporous layer), etched with acid, washed with water, dried by heating, and heat-treated at 350 ° C. for 1 hour. The platinum amount is 0.14 mg / cm ² (28 layers) with a PtCo alloy catalyst.

(Production of membrane electrode assembly)
(Examples 1 to 16)
The anode electrode and the cathode electrode are each cut into 20 mm squares. The anode electrode, the laminated electrolyte membranes M1 to M15, and the cathode electrode were sequentially stacked and pressed with a hot press (12.5 kg / cm ² , 165 ° C., 4 minutes), and then cooled to room temperature to prepare an MEA. The results are shown in Table 2. However, the electrolyte membrane 11 side was arranged on the cathode side and produced.

(Comparative Examples 1-4)
The MEA (Comparative Examples 1 to 4) was manufactured using the nafion 115 and the composite electrolyte membranes C1 to C3 under the same conditions as the above MEA. The results are shown in Table 2.

(Evaluation of water electrolysis)
The titanium water electrolysis cell used a single cell (anode and cathode; straight flow path) with an electrode area of 4 cm ² as the anode and cathode power supply (integrated with the separator) using a titanium flow path plate. . At normal pressure, the cell temperature was 80 ° C., heated by a heater so as to maintain the temperature, and ion-exchanged water was circulated at the anode several times the amount necessary for water splitting. In water electrolysis, water decomposition was performed at an electric current density of 2 A / cm ² using an electronic load device manufactured by Kikusui Co., Ltd. at a cell temperature of 80 ° C. Table 2 shows the results of measurement of the water decomposition voltage and AC impedance resistance of 1 KHz.

(Measurement of hydrogen crossover)
Water decomposition was performed at a constant current under the above water electrolysis conditions, water was separated from the gas coming out from the anode side, collected for 30 minutes, and then the hydrogen concentration was measured by GC-MS. The measurement was performed after 50 hours and after 500 hours, and the measurement results are shown in Table 2.

  Compared to Comparative Example 4 using nafion 115, which is standard for PEM-type water electrolysis, MEA using a laminated electrolyte membrane in both cases has a significantly lower crossover and lower resistance. The voltage is low and the efficiency is high. In Comparative Examples 5 to 7 (composite electrolyte membrane in which Pt 3 is dispersed in the membrane), it is possible to reduce the initial crossover, but after 500 hours, it is doubled or more and a significant increase is observed. However, the MEA using the multilayer electrolyte membrane 100 increases only about 20% at the maximum in 500 hours. Therefore, an MEA having a small crossover and a low film resistance was obtained.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope of the description and the gist, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane; 2 ... Electrolyte membrane; 3 ... Nanosheet lamination | stacking catalyst layer; 4 ... Transfer layer; 5 ... Cathode feeder; 6 ... 1st electrode; 7 ... 2nd electrode; 8 ... Gasket (seal); (Seal); 10 ... Cathode feeder; 11 ... Separator; 13 ... Separator; 14 ... Clamping plate; 15 ... Clamping plate; 12 ... Anode feeder; 13 ... Separator; 18 ... Gas-liquid separator; 19 ... Hydrogen purifier; 20 ... Gas-liquid separator; 21 ... Power source; 22 ... Pump; 23 ... Check valve; 24 ... Valve; 100 ... Multilayer electrolyte membrane; 300 ... Water electrolysis cell; 400 ... Stack; 500 ... Water electrolysis device, 600 ... Hydrogen utilization system, 61 ... Power source, 62 ... Hydrogen power generation device, 63 ... Hydrogen gas tank, 64 ... Drive device,
DESCRIPTION OF SYMBOLS 700 ... Hydrogen utilization system, 71 ... Electric power source, 72 ... Gas-liquid separator, 73a ... Mixing tank, 73b ... Hydrogen gas tank, 74 ... Ion exchange water manufacturing apparatus, 75a ... Pump, 75b ... Check valve, 76 ... Gas-liquid Separation device, 77 ... hydrogen purification device, 78 ... valve, 79 ... drive device

Claims (16)

A first electrolyte membrane;
A second electrolyte membrane;
A nanosheet laminated catalyst layer comprising a laminated structure provided between the first electrolyte membrane and the second electrolyte membrane, wherein a plurality of nanosheet catalysts are laminated with a gap;
A multilayer electrolyte membrane comprising: The multilayer electrolyte membrane according to claim 1, wherein the nanosheet-shaped catalyst contains Pt or a Pt alloy. The multilayer electrolyte membrane according to claim 1 or 2, wherein the nanosheet laminated catalyst layer has a thickness of 10 nm or more and 2000 nm or less. 4. The multilayer electrolyte membrane according to claim 1, wherein a thickness of the multilayer electrolyte membrane is 25 μm or more and 250 μm or less. 5. The multilayer electrolyte membrane according to any one of claims 1 to 4, wherein a radical scavenger or a hydrogen peroxide decomposing agent is added to the multilayer electrolyte membrane. The multilayer electrolyte membrane according to any one of claims 1 to 5, wherein the gap contains porous carbon or ceramics containing fibrous carbon. The multilayer electrolyte membrane according to any one of claims 1 to 6, wherein a pore area ratio of the multilayer structure is 50% or more and 90% or less. The membrane electrode assembly in which the multilayer electrolyte membrane according to any one of claims 1 to 6 is provided between the first electrode, the second electrode, and the first electrode and the second electrode. The membrane electrode assembly according to claim 8, wherein the first electrode is a cathode and the second electrode is an anode. The membrane electrode assembly according to claim 9, wherein the electrolyte membrane in contact with the second electrode is a pearl fluorosulfonic acid electrolyte membrane. The membrane electrode assembly according to any one of claims 8 to 10, wherein the nanosheet laminated catalyst layer and the first electrode or the second electrode are separated from each other. The membrane electrode assembly according to any one of claims 8 to 11, wherein the first electrode includes a laminated structure in which a plurality of nanosheet-shaped catalysts are laminated with a gap.   A cell for water electrolysis using the membrane electrode assembly according to any one of claims 8 to 12.   A stack using the membrane electrode assembly according to any one of claims 8 to 12 or the water electrolysis cell according to claim 13.   A water electrolysis apparatus using the membrane electrode assembly according to any one of claims 8 to 12, the water electrolysis cell according to claim 13, or the stack according to claim 14.   A hydrogen utilization system using the water electrolysis apparatus according to claim 15.