JP2010027605A - Ion conductive structure, ion conducting polymer composite membrane, membrane electrode assembly, fuel cell, method of producing ion conductive structure, and method of producing ion conducting polymer composite membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ion conductive polymer composite membrane having both high gas barrier properties and high proton conductivity, a membrane electrode assembly using the ion conductive polymer composite membrane, a fuel cell, and a method for producing an ion conductive structure And a method for producing an ion conductive polymer composite membrane.
An ion conductive structure comprising an inorganic layered structure having a plurality of layers made of an inorganic compound and an ion exchange group bonded to the inorganic layered structure.
The ion-conductive structure, wherein the ion exchange group is bonded to any of a plurality of surfaces of the layer made of the inorganic compound.
[Selection] Figure 2

Description

  The present invention relates to an ion conductive structure, an ion conductive polymer composite membrane, a membrane electrode assembly, a fuel cell, a method for producing an ion conductive structure, and a method for producing an ion conductive polymer composite membrane.

  As a method for improving the gas barrier performance of ion conductive polymer membranes such as a Nafion membrane (registered trademark, manufactured by DuPont), Patent Document 1 discloses an inorganic layered structure using a silanol group possessed by an inorganic layered structure. A technique is described in which an ion conductive structure obtained by bonding a sulfonic acid group to a body is dispersed in an ion conductive polymer membrane.

JP 2006-327932 A

  However, in Patent Document 1, since montmorillonite having a silanol group only on the end face is used as the inorganic layered compound, as shown in FIG. 1, the sulfonic acid group can be bonded only to the end face of the inorganic layered compound. The proton conductivity of the obtained ion conductive polymer composite membrane was not sufficient.

  Therefore, in the present invention, an ion conductive polymer composite membrane having both high gas barrier properties and high proton conductivity, a membrane electrode assembly and a fuel cell using the ion conductive polymer composite membrane, the ion conductive high It is an object of the present invention to provide an ion conductive structure for forming a molecular composite film, a method for producing an ion conductive structure, and a method for producing an ion conductive polymer composite film.

The first of the present invention is an ion conductive structure comprising an inorganic layered structure having a plurality of layers made of an inorganic compound, and an ion exchange group bonded to the inorganic layered structure.
The ion-conductive structure is characterized in that the ion-exchange group is bonded to any of a plurality of surfaces of the layer made of the inorganic compound.

  The second of the present invention is an ion conductive polymer composite film comprising the ion conductive structure and an ion conductive polymer film.

  A third aspect of the present invention is a membrane electrode assembly comprising an ion conductive polymer composite membrane and two catalyst layers in contact with the ion conductive polymer composite membrane.

  A fourth aspect of the present invention includes the membrane electrode assembly, two gas diffusion layers in contact with the membrane electrode assembly, and two current collectors in contact with the two gas diffusion layers, respectively. This is a featured fuel cell.

  The fifth aspect of the present invention includes a step of bonding an ion exchange group by substituting a proton of the silanol group to an inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side. This is a method for producing an ion conductive structure.

The sixth of the present invention is
(I) An ion-conductive structure is formed by binding an ion exchange group to an inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side, by substituting protons of the silanol group. And a process of
(Ii) dispersing the ion conductive structure in an ion conductive polymer film;
It is a manufacturing method of the ion conductive polymer composite film characterized by having.

  According to the present invention, an ion conductive polymer composite membrane having both high gas barrier properties and high proton conductivity, a membrane electrode assembly and a fuel cell using the ion conductive polymer composite membrane, the ion conductive high An ion conductive structure for forming a molecular composite film, a method for producing an ion conductive structure, and a method for producing an ion conductive polymer composite film can be provided.

It is a schematic diagram which shows the ion conductive structure described in patent document 1. It is a schematic diagram which shows an example of the ion conductive structure of this invention. It is a schematic diagram which shows an example of the layer which consists of an inorganic compound in this invention. It is a schematic diagram which shows an example of the membrane electrode assembly of this invention. It is a schematic diagram which shows an example of the fuel cell of this invention. It is a schematic diagram which shows an example of the manufacturing method of the ion conductive structure of this invention.

  Hereinafter, the present invention will be described in detail with reference to the drawings.

The first of the present invention is
In an ion conductive structure comprising an inorganic layered structure having a plurality of layers made of an inorganic compound, and an ion exchange group bonded to the inorganic layered structure,
The ion-conductive structure is characterized in that the ion-exchange group is bonded to any of a plurality of surfaces of the layer made of the inorganic compound.

  FIG. 2 is a diagram showing an example of an ion conductive structure which is the first of the present invention. In the figure, 2 is a layer made of an inorganic compound, and an ion exchange group A is bonded to the surface of the layer 2 made of an inorganic compound. The inorganic layered structure 3 is an aggregate of the layers 2 made of an inorganic compound, and 1 is an ion conductive structure. In FIG. 2, the ion conductive structure 1 is described as being composed of a layer composed of two inorganic compounds to which the ion exchange group A is bonded. What is necessary is just to be comprised by the layer which consists of a some inorganic compound which group A couple | bonded.

  The ion exchange group A is bonded to any surface of the layer 2 made of an inorganic compound. In other words, at least one ion exchange group A is bonded to each of the plurality of surfaces of the layer 2 made of an inorganic compound. Specifically, when the layer made of an inorganic compound has a rectangular parallelepiped shape as shown in FIG. 3, ion exchange is performed on each of all surfaces (six surfaces) including the main surfaces 4 and 5 and the end surfaces 6 and 7. One or more groups A are bonded. Here, the main surface is the two surfaces having the largest area among the surfaces of the rectangular parallelepiped, and the end surface is the two surfaces having the smallest area. When the layer made of an inorganic compound is not a perfect rectangular parallelepiped shape, a rectangular parallelepiped circumscribing the layer is assumed, and light is projected onto the layer when light is irradiated from the outside perpendicularly to each surface of the rectangular parallelepiped. Is defined as the surface of the layer.

  The inorganic layered structure is an aggregate of layers made of an inorganic compound and has a plurality of layers made of an inorganic compound. Here, in the present invention, the inorganic compound is a compound containing no carbon, an allotrope of carbon such as graphite or diamond, a metal carbonate such as carbon monoxide, carbon dioxide or calcium carbonate, hydrocyanic acid and metal cyanate, and metal cyanate. Salt and metal thiocyanate are shown.

  In the present invention, a “layer” has an aspect ratio of 20 or more. The aspect ratio of the structure a is [the length of the line segment (a) having the maximum length among the line segments that can exist in the structure a] / [perpendicular to the line segment (a)]. The length of the line segment (A) having the maximum length among the line segments that can exist in the structure a]. The length of the line segment (a) and the length of the line segment (a) were measured using a transmission electron microscope (TEM) and an atomic force microscope (AFM) for the layer made of the peeled inorganic layered compound. The length of the line segment (A) can be inferred from the chemical structure of the inorganic layered compound.

  Examples of such an inorganic layered structure include magadiite, kenyanite, and kanemite. Among these, it is preferable to use magadiite because of its high structural stability.

  An inorganic layered structure generally has a structure in which layers made of negatively charged inorganic compounds are stacked with a gap between the layers because the shortage of charges is compensated by cations existing between the layers. ing. The ion exchange group A is bonded to the surface of the layer 2 made of an inorganic compound by a covalent bond. In the present invention, the ion exchange group is an ion dissociable functional group, and examples thereof include sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid, and phosphonous acid. In addition, as long as one or more ion exchange groups are bonded to any surface of the layer made of an inorganic compound, the ion exchange groups A may not all be the same ion exchange group. May exist.

  Next, the second aspect of the present invention will be described.

  A second aspect of the present invention is an ion conductive polymer composite film comprising the ion conductive structure according to the first aspect of the present invention and an ion conductive polymer film.

  The ion conductive polymer membrane is made of a polymer compound having an ion exchange group, and can hold the ion conductive structure which is the first of the present invention. The ion conductive structure is preferably dispersed in an ion conductive polymer film.

  Examples of such ion conductive polymer membranes include perfluorosulfonic acid polymers such as Nafion (registered trademark), polyamides, polyamideimides, polyimides, polyether ketones, polyether ether ketones having ion exchange groups. , Polyphenylene, polyphenylene ether, polyester, polycarbonate, polyethylene, polypropylene, polyester, porstyrene, polyacetal, polysulfone, poly (meth) acrylic acid derivatives, block copolymers composed of ion conductive blocks and non-ion conductive blocks May be used.

  Since the ion conductive structure used in the present invention swells by absorbing water molecules between layers, if it is contained in a large amount, the output may be lowered when used as an electrolyte membrane of a fuel cell. Therefore, the content of the ion conductive structure is 50% by weight or less, preferably 30% by weight or less, more preferably 10% by weight or less, based on the weight of the ion conductive polymer film.

  In addition, as an ion conductive structure contained in an ion conductive polymer composite film, one type of ion conductive structure may be used, or a plurality of types of ion conductive structures may be used.

  A third aspect of the present invention is a membrane electrode joint comprising the ion conductive polymer composite membrane according to the second aspect of the present invention and two catalyst layers in contact with the ion conductive polymer composite membrane. Is the body.

  A third example of the present invention is shown in FIG.

The third membrane electrode assembly 11 according to the present invention includes an ion conductive polymer composite membrane 8 and two catalyst layers 9 and 10 that are in contact with the ion conductive polymer composite membrane.
The two catalyst layers 9 and 10 (the anode-side catalyst layer 9 and the cathode-side catalyst layer 10) are composed of a structure made of a catalyst such as a metal catalyst such as platinum or an alloy catalyst of platinum and a metal other than platinum such as ruthenium. It is possible to use a layer formed by dispersing and supporting the above structure on a carrier such as carbon. Here, the structure that can be used for the catalyst layer may have a particle shape or a shape other than particles, such as a dendritic shape.

  When forming the membrane electrode assembly according to the third aspect of the present invention, the ion conductive polymer composite membrane 8 is sandwiched between the catalyst layer 9 and the catalyst layer 10, the temperature is 130 to 150 ° C., and the pressurization time is 1 to 30 minutes. It is preferable to perform hot pressing in a pressure range of 1 to 40 MPa.

  Next, the fourth aspect of the present invention will be described.

  A fourth aspect of the present invention is the membrane electrode assembly according to the third aspect of the present invention, two gas diffusion layers in contact with the membrane electrode assembly, two current collectors in contact with the gas diffusion layers, It is a fuel cell characterized by having.

FIG. 5 is a cross-sectional view showing an example of a fuel cell according to the fourth aspect of the present invention, 11 is a membrane electrode assembly according to the third aspect of the present invention, 14 is an anode side gas diffusion layer, and 15 is a cathode side gas diffusion. The layer, 16 is an anode side current collector, and 17 is a cathode side current collector.
The anode side gas diffusion layer 14 and the cathode side gas diffusion layer 15 have a role of supplying oxygen or fuel to the membrane electrode assembly 11. The anode side gas diffusion layer 14 and the cathode side gas diffusion layer 15 are preferably composed of a plurality of sublayers. In the case of being composed of a plurality of sublayers, the sublayers that are in contact with the membrane electrode assembly 11 among the sublayers of the anode side gas diffusion layer 14 and the cathode side gas diffusion layer 15 are more porous than the other sublayers. It is preferable that the average diameter is small. Specifically, when the gas diffusion layer is composed of two sublayers, as shown in FIG. 5, the gas diffusion layer contacts the membrane electrode assembly 11 of the anode side gas diffusion layer 14 and the cathode side gas diffusion layer 15. The average diameter of the holes in the sublayer 12 is preferably smaller than the average diameter of the other sublayers 13 constituting the anode side gas diffusion layer 14 and the cathode side gas diffusion layer 15.

  In the following, the sublayers of the anode-side gas diffusion layer 14 and the cathode-side gas diffusion layer 15 that are in contact with the membrane electrode assembly 11 have a smaller average hole diameter than the other sublayers. The sublayer in contact with the membrane electrode assembly 8 may be referred to as a microporous layer (MPL).

  The MPL can be composed of, for example, carbon fine particles using PTFE as a binder. Examples of the carbon fine particles include acetylene black, ketjen black, fibrous carbon formed by vapor phase growth, and carbon nanotube.

  Among the sublayers constituting the anode side gas diffusion layer 14 and the cathode side gas diffusion layer 15, carbon cloth, carbon paper, porous metal, or the like can be used for portions other than the MPL. Further, MPL and a plurality of these can be stacked, or MPL and one of these can be stacked to be used as a gas diffusion layer having a structure composed of three sublayers. In addition, when using a metal material for a sublayer, it is preferable to use the material excellent in oxidation resistance. Specifically, SUS316L, nickel chromium alloy, titanium, or the like can be used. As an example of the nickel-chromium alloy porous metal, for example, Celmet (registered trademark) manufactured by Toyama Sumitomo Electric Co., Ltd. can be used.

  As the material for the anode-side current collector 16 and the cathode-side current collector 17, a material having excellent conductivity and oxidation resistance is used. Examples of such a material include platinum, titanium, carbon, stainless steel (SUS), SUS coated with gold, SUS coated with carbon, aluminum coated with gold, and aluminum coated with carbon.

  Next, a fifth aspect of the present invention will be described.

  A fifth aspect of the present invention includes a step of bonding an ion exchange group A by substituting a proton of the silanol group to an inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side. This is a method for producing an ion conductive structure.

  Hereinafter, a description will be given with reference to FIG.

  The inorganic layered structure shown in (a) has a plurality of layers made of an inorganic compound having a silanol group on either side. An inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side is the same as the first inorganic layered structure of the present invention except that it has a silanol group instead of an ion exchange group It is.

  Examples of the method for binding the ion exchange group A by substituting the proton of the silanol group include the following methods. The silanol group of the inorganic layered structure is silylated by a silane compound having an ion exchange group A or a silane compound having a group that becomes an ion exchange group A by an oxidation reaction, and ion exchange groups are bonded or ion exchange is performed by an oxidation reaction. For example, a method may be used in which a base group is bonded and oxidized. Thereby, as shown to (b), the ion conductive structure which is an inorganic layered structure to which the ion exchange group A couple | bonded can be obtained.

  More specifically, for example, a silanol group of the inorganic layered structure is reacted with a silane compound having a mercapto group such as 3-mercaptopropyltrimethoxysilane in an organic solvent to bond the mercapto group. An inorganic layered structure is obtained. And an inorganic layered structure to which a sulfonic acid group which is an ion exchange group is bonded can be obtained by sulfonating a mercapto group with an oxidizing agent such as hydrogen peroxide.

  FIG. 6 is a schematic diagram, where (a) shows only the OH group of the silanol group, and (b) shows only the ion exchange group A when the silanol group is silylated as an end group.

  In such a case, in order to perform silanol group silylation reaction in an organic solvent, it is necessary to hydrophobize the inorganic layered material. However, when metal ions exist between the layers of the inorganic layered structure, The inorganic layered structure can be easily hydrophobized by substituting with a surfactant.

  Examples of surfactants that can be used for hydrophobization include amine surfactants such as propylamine, octylamine, and dodecylamine, and quaternary compounds such as dodecyltrimethylammonium bromide, cetyltrimethylammonium bromide, and stearyltrimethylammonium bromide. Examples thereof include ammonium salt surfactants.

Next, the sixth of the present invention is
(I) An ion-conductive structure is formed by binding an ion exchange group to an inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side, by substituting protons of the silanol group. And a process of
(Ii) dispersing the ion conductive structure in an ion conductive polymer film;
It is a manufacturing method of the ion conductive polymer composite film characterized by having.

Since the step (i) is the same as the step in the fifth aspect of the present invention, the step (ii) will be described here.
As a method for dispersing the ion conductive structure obtained in the step (i) in the ion conductive polymer film, for example, the following method can be used.

  As a first method, a solution (a) in which the ion conductive structure obtained in (i) is dispersed in a solution made of a monomer that becomes an ion conductive polymer film is prepared, and the solution (a) A method of polymerizing a monomer, applying it to the substrate surface, and forming a film can be mentioned.

  The polymerization reaction is not particularly limited as long as the polymerization reaction is not stopped by the ion exchange group of the inorganic layered structure. For example, radical polymerization in which the polymerization reaction proceeds without being affected by the ion exchange group is preferable. As the radical polymerization initiator, a peroxide polymerization initiator such as benzoyl peroxide or an azo polymerization initiator such as azobisisobutyronitrile can be used. The solvent of the solution (a) may be any solvent that can disperse the inorganic layered structure and the monomer. For example, N-dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), γ-butyrolactone, tetrahydrofuran, 1,4-dioxane, dichloromethane, chloroform, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol mono It is possible to use ethyl ether, methanol, ethanol, propanol or the like, or a mixed solvent in which two or more of the above-mentioned solvents are mixed.

  The solution (a) after the termination of the polymerization reaction may be applied directly to the substrate surface, or a solution re-dispersed in a solvent after purification and recovery of the solution (a) may be applied to the substrate surface. As a method for applying to the substrate surface, a bar coating method, a gravure coating method, a spin coating method, a dip coating method, a roll coating method, a spray method, a casting method, or the like can be used.

  As a second method, the ion conductive polymer and the ion conductive structure constituting the ion conductive polymer film are mechanically kneaded at a temperature equal to or higher than the glass transition temperature of the ion conductive polymer. The method of apply | coating to a substrate surface and forming into a film is mentioned.

  As a third method, a solution (b) in which an ion conductive structure is dispersed in a solution made of an ion conductive polymer is prepared, and the solution (b) is applied to the substrate surface to form a film. Can be mentioned.

  As a method for applying the solution (b) to the substrate surface, a bar coating method, a gravure coating method, a spin coating method, a dip coating method, a roll coating method, a spray method, a casting method, or the like can be used.

  Further, as the solvent of the solution (b), the same solvent as the solvent of the solution made of the monomer that becomes the ion conductive polymer membrane can be used in the first method.

  In addition, when disperse | distributing an ion conductive structure to the solution which consists of an ion conductive polymer, you may use an ultrasonic cleaner and a homogenizer. By using any of these, the dispersibility of the ion conductive structure in the solution (b) can be improved. Further, the dispersion state of the ion conductive structure in the ion conductive polymer composite film can be easily confirmed by observation of an ultrathin section with a transmission electron microscope (TEM).

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to these Examples.

(Synthesis Example 1) Production of H-montmorillonite As a clay mineral mainly composed of aluminum hydrated silicate, 5 g of montmorillonite from Tsukibu, Yamagata Prefecture was stirred in 500 ml of 1N hydrochloric acid for 24 hours. After the reaction, the mixture was centrifuged at 10,000 rpm for 15 minutes, the supernatant was removed, and then dispersed again in water. H-montmorillonite in which sodium ions existing between montmorillonite layers were replaced with protons was prepared by repeating reprecipitation by centrifugation and washing with water twice.

(Synthesis Example 2) Production of magadiite 20 g of silica gel (Wakogel Q63, manufactured by Wako Pure Chemical Industries, Ltd.), 3.07 g of sodium hydroxide and 111 g of pure water were sealed in a PTFE sealed container and hydrothermally heated at 150 ° C. for 48 hours. The reaction was carried out under conditions to synthesize magadiite.

(Synthesis Example 3) Preparation of Kenyaite 20 g of silica gel (Wakogel Q63, manufactured by Wako Pure Chemical Industries), 3.07 g of sodium hydroxide and 111 g of pure water were sealed in a PTFE sealed container, and hydrothermal conditions at 200 ° C. for 6 hours. Kenyaite was synthesized by reacting under the following conditions.

(Synthesis Example 4) Preparation of sulfonated magadiite 2 ml of mercaptopropyltrimethoxysilane was gradually added dropwise to a mixed solution of 1.8 ml of water, 100 μl of 35% hydrochloric acid and 10 ml of ethanol, and stirred at 50 ° C. for 1 hour. The obtained solution was mixed with a solution in which 10 g of magadiite synthesized in Synthesis Example 2 was dispersed in 60 ml of ethanol and stirred at 70 degrees for 13 hours.
By stirring 10 g of the synthesized magadiite having a mercapto group in a mixed solution of 40 ml of ethanol and 10 ml of hydrogen peroxide at 70 ° C. for 2 hours, the mercapto group was substituted with a sulfonic acid group to obtain a sulfonated magadiite.

(Synthesis Example 5) Production of sulfonated kayatite 2 ml of mercaptopropyltrimethoxysilane was gradually added dropwise to a mixed solution of 1.8 ml of water, 100 μl of 35% hydrochloric acid and 10 ml of ethanol, and stirred at 50 ° C. for 1 hour. The obtained solution was mixed with a solution in which 10 g of Kenyaite synthesized in Synthesis Example 3 was dispersed in 60 ml of ethanol and stirred at 70 degrees for 13 hours.
By stirring 10 g of the synthesized magadiite having a mercapto group in a mixed solution of 40 ml of ethanol and 10 ml of hydrogen peroxide at 70 ° C. for 2 hours, the mercapto group was substituted with a sulfonic acid group to obtain a sulfonated magadiite.

Synthesis Example 6 Production of Sulfonated Montmorillonite Mercaptopropyltrimethoxysilane (2 ml) was gradually added dropwise to a mixed solution of water (1.8 ml), 35% hydrochloric acid (100 μl), and ethanol (10 ml), followed by stirring at 50 ° C. for 1 hour. The obtained solution was mixed with a solution in which 10 g of montmorillonite from Tsuki cloth was dispersed in 60 ml of ethanol and stirred at 70 degrees for 13 hours.
By stirring 10 g of the synthesized montmorillonite having a mercapto group in a mixed solution of 40 ml of ethanol and 10 ml of hydrogen peroxide at 70 ° C. for 2 hours, the mercapto group was substituted with a sulfonic acid group to obtain a sulfonated montmorillonite.

Example 1 Nafion / sulfonated magadiite composite membrane A Nafion 5 wt% solution was prepared. Subsequently, the sulfonated magadiite obtained in Synthesis Example 4 was dispersed in a Nafion solution to obtain a mixed solution in which the weight ratio of Nafion and sulfonated magadiite was 90:10. Subsequently, the sulfonated magadiite was further sufficiently dispersed in the mixed solution using an ultrasonic cleaner. Subsequently, the mixed solution was formed into a film by a solvent casting method in a nitrogen atmosphere. The film thickness after film formation was 40 μm.

Subsequently, AC impedance measurement (voltage amplitude 5 mV, frequency 1 Hz to 1 MHz) was performed by the four probe method, and the conductivity in the film surface direction of the ion conductive polymer composite film was calculated from the obtained resistance value. As a result, the ionic conductivity at a temperature of 50 ° C. and a relative humidity of 50% was 3.12 × 10 ⁻² S · cm ⁻¹ .

(Example 2) Nafion / sulfonated Kenyaite composite membrane A Nafion 5 wt% solution was prepared. Subsequently, the sulfonated Kenyaite obtained in Synthesis Example 5 was dispersed in a Nafion solution to obtain a mixed solution in which the weight ratio of Nafion and sulfonated magadiite was 90:10. Subsequently, the sulfonated Kenyaite was further sufficiently dispersed in the mixture using an ultrasonic cleaner. Subsequently, the mixed solution was formed into a film by a solvent casting method in a nitrogen atmosphere. The film thickness after film formation was 40 μm.

Subsequently, AC impedance measurement (voltage amplitude 5 mV, frequency 1 Hz to 1 MHz) was performed by the four probe method, and the conductivity in the film surface direction of the ion conductive polymer composite film was calculated from the obtained resistance value. As a result, the ionic conductivity at a temperature of 50 ° C. and a relative humidity of 50% was 2.77 × 10 ⁻² S · cm ⁻¹ .

Comparative Example 1 Nafion / H-montmorillonite composite film A Nafion 5 wt% solution was prepared. Subsequently, the H-montmorillonite obtained in Synthesis Example 1 was dispersed in a Nafion solution to obtain a mixed solution in which the weight ratio of Nafion to sulfonated magadiite was 90:10. Subsequently, H-montmorillonite was further sufficiently dispersed in the mixed solution using an ultrasonic cleaner. Subsequently, the mixed solution was formed into a film by a solvent casting method in a nitrogen atmosphere. The film thickness after film formation was 40 μm.

AC impedance measurement (voltage amplitude 5 mV, frequency 1 Hz to 1 MHz) was performed by the four-terminal method, and the conductivity in the film surface direction of the ion conductive polymer composite film was calculated from the obtained resistance value. As a result, the ionic conductivity at a temperature of 50 ° C. and a relative humidity of 50% was 2.55 × 10 ⁻³ S · cm ⁻¹ .

Comparative Example 2 Nafion / sulfonated montmorillonite composite membrane A Nafion 5 wt% solution was prepared. Subsequently, the sulfonated montmorillonite obtained in Synthesis Example 6 was dispersed in a Nafion solution to obtain a mixed solution in which the weight ratio of Nafion and sulfonated montmorillonite was 90:10. Subsequently, the sulfonated montmorillonite was further sufficiently dispersed in the mixed solution using an ultrasonic cleaner. Subsequently, the mixed solution was formed into a film by a solvent casting method in a nitrogen atmosphere. The film thickness after film formation was 40 μm.

AC impedance measurement (voltage amplitude 5 mV, frequency 1 Hz to 1 MHz) was performed by the four probe method, and the conductivity in the film surface direction of the ion conductive polymer composite film was calculated from the obtained resistance value. As a result, the ionic conductivity at a temperature of 50 ° C. and a relative humidity of 50% was 5.69 × 10 ⁻³ S · cm ⁻¹ .

  The results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1.

(Example 3)
An example of a method for producing a membrane-electrode assembly and a fuel battery cell is shown below.

HiSPEC1000 (registered trademark, manufactured by Johnson & Massey) was used as the catalyst powder, and a Nafion solution was used as the solution of the ion conductive electrolyte used for the catalyst layer. First, a mixed dispersion of catalyst powder and Nafion solution was prepared, and formed on a PTFE sheet using a doctor blade method to prepare a catalyst sheet. Next, the produced catalyst sheet was hot-press-transferred onto the electrolyte membrane obtained in Example 1 at 120 ° C. and 100 kgf / cm ² by a decal method to produce a membrane-electrode assembly. Further, the membrane-electrode assembly was sandwiched between carbon cross electrodes (manufactured by E-TEK) and then clamped with a current collector to produce a fuel cell.

Using the prepared fuel cell, hydrogen gas was injected into the anode side at an injection rate of 300 ml / min, air was supplied to the cathode side, the cell outlet pressure was atmospheric pressure, the relative humidity was 50% for both the anode and cathode, and the cell temperature was The temperature was 50 ° C. When constant current measurement was performed at a current density of 400 mA / cm ² , the cell potential was 810 mV, and stable characteristics were maintained even after 100 hours.

DESCRIPTION OF SYMBOLS 1 Ion conductive structure 2 Layer which consists of inorganic compounds 3 Inorganic layered structure 4, 5 Main surface 6, 7 End surface 8 Ion conductive polymer composite film 9 Anode side catalyst layer 10 Cathode side catalyst layer 11 Membrane electrode assembly 12 Sublayer 13 Sublayer 14 Anode side gas diffusion layer 15 Cathode side gas diffusion layer 16 Anode side current collector 17 Cathode side current collector 18 Inorganic layered compound 19 Ion conductive inorganic layered material

Claims (9)

In an ion conductive structure comprising an inorganic layered structure having a plurality of layers made of an inorganic compound, and an ion exchange group bonded to the inorganic layered structure,
The ion-conductive structure, wherein the ion exchange group is bonded to any of a plurality of surfaces of the layer made of the inorganic compound.   The ion conductive structure according to claim 1, wherein the inorganic layered structure is made of any one of magadiite, kenyanite, and kanemite.   3. The ion conductive structure according to claim 1, wherein the ion exchange group is any one of sulfonic acid, carboxylic acid, phosphoric acid, phosphonic acid, and phosphonous acid.   An ion conductive polymer composite film comprising the ion conductive structure according to claim 1 and an ion conductive polymer film.   A membrane electrode assembly comprising the ion conductive polymer composite membrane according to claim 4 and two catalyst layers in contact with the ion conductive polymer composite membrane.   The membrane electrode assembly according to claim 5, two gas diffusion layers in contact with the membrane electrode assembly, and two current collectors in contact with the two gas diffusion layers, respectively. Fuel cell.   Ion conductivity characterized by having a step of bonding an ion exchange group by substituting a proton of the silanol group to an inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side Manufacturing method of structure. The step of binding an ion exchange group by substituting a proton of the silanol group,
The method for producing an ion conductive structure according to claim 7, wherein the silanol group is silylated and the silylated silanol group is oxidized. (I) a step of forming an ion conductive structure by bonding an ion exchange group to the inorganic layered structure having a plurality of layers made of an inorganic compound having a silanol group on either side through the silanol group;
(Ii) dispersing the ion conductive structure in an ion conductive polymer film;
A process for producing an ion-conductive polymer composite membrane, comprising:

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