JP2004311147A - Manufacturing method of proton conductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a flexible proton conductive sheet using an inorganic system proton conductive material as a solid electrolyte. <P>SOLUTION: The manufacturing method of the proton conductive sheet includes preparing of a sol containing a polysiloxane system proton conductive material, forming of a proton conductive film 30 after deposition from the sol and putting it under heat treatment, coating the sol on the surface of a first and a second porous and conductive sheet materials 12, 22, and crimping the proton conductive film 30 while pinched by the first and the second sheet materials 12, 22 coated with the sol. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a flexible proton conductive sheet having excellent proton conductivity.
[0002]
[Prior art]
Substances in which ions move in a solid have been energetically studied as materials for electrochemical devices such as batteries.⁺, Ag⁺, H⁺, F⁻For example, ion conductive materials of various conductive ion species have been found. Among them, proton (H⁺) Is expected to be applied to various electrochemical devices such as fuel cells, capacitors, and electrochromic display devices. In a fuel cell using hydrogen as a fuel, a reaction represented by the following equation (i) occurs. Protons generated by this reaction move through the electrolyte and are consumed at the air electrode by the reaction of formula (ii). That is, a fuel cell using hydrogen as a fuel can be formed by using a proton conductive material as an electrolyte.
[0003]
H₂  → 2H⁺  + 2e⁻              (I)
1 / 2O₂  + 2H⁺  → H₂O (ii)
2. Description of the Related Art Fuel cells are expected to be used as power sources for generating relatively large currents, such as for stationary and electric vehicles. For such an application, it is necessary to form a large-area solid electrolyte layer. A proton conductive material can be used as an electrolyte of the fuel cell.
[0004]
Ideally, the proton conductive material exhibits high proton conductivity from a low temperature of 0 ° C. or lower to a high temperature of 100 ° C. or higher, and also in a low humidity to high humidity region. At present, as a proton conductive material, organic substances such as a polymer ion exchange membrane having a side chain containing a perfluorosulfonic acid group in a perfluoroalkane polymer, or uranyl phosphate hydrate or molybdo phosphate hydrate, etc. Inorganic substances are known. However, with these materials, it may be difficult to obtain sufficient proton conductivity under such a wide range of environmental conditions.
[0005]
For example, in the above-mentioned inorganic proton conductive material,
In addition, since protons in the crystallization water participate in conduction, there is a problem that the crystallization water is desorbed at high temperatures, particularly under low humidity conditions, and the proton conductivity is reduced.
[0006]
In addition, as a method of forming the inorganic substance into a thin film, a vapor deposition method, a casting method, and the like are given. However, in the thin film forming method by the vapor deposition method, the production cost is high and it is difficult to obtain a large area thin film. Further, a thin film made of an inorganic proton conductive material is generally brittle, so that it has been difficult to apply it to the above-mentioned applications.
[0007]
[Patent Document 1]
JP-A-10-69817
[Patent Document 2]
JP-A-2002-80214
[Patent Document 3]
JP-A-2002-97272
[0008]
[Problems to be solved by the invention]
The present invention provides a method for producing a flexible proton conductive sheet using an inorganic proton conductive material as a solid electrolyte.
[0009]
[Means for Solving the Problems]
The method for producing a proton conductive sheet according to the present invention includes:
Prepare a sol containing a polysiloxane-based proton conductive material,
By performing a heat treatment after forming the sol, a proton conductive membrane is formed,
Coating the sol on the surface of a porous and conductive first and second sheet material,
Pressing the sol coated with the proton conductive membrane sandwiched between the first and second sheet materials,
including.
[0010]
Here, in the above manufacturing method, at least one of the first and second sheet materials may be made of a carbon material containing platinum.
[0011]
Here, in the above production method, the proton conductive membrane may be a hydrolyzed condensate of a polyalkoxysilane, and may include a compound having at least one of a phosphate group and a sulfonic acid group.
[0012]
Here, in the above production method, the sol may further include an organic polymer.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
As shown in FIG. 1, a proton conductive sheet 100 according to the present embodiment has first and second sheet materials 12 and 22, and a proton conductive membrane sandwiched between the first and second sheet materials 12 and 22. 30.
[0014]
The first and second sheet materials 12 and 22 include a polysiloxane-based proton conductive material. Specifically, the polysiloxane-based proton conductive material contained in the first and second sheet materials 12 and 22 is a sol-shaped polysiloxane-based proton conductive material formed on the surface of the first and second sheet materials 12 and 22. And then gelled.
[0015]
The proton conductive membrane 30 is made of a polysiloxane-based proton conductive material. Specifically, the proton conductive film 30 is formed by gelling a sol-like polysiloxane-based proton conductive material after film formation.
[0016]
That is, the proton conductive material included in the first and second sheet materials 12 and 22 and the proton conductive material forming the proton conductive membrane 30 are both polysiloxane-based proton conductive materials. Here, the polysiloxane-based proton conductive material is a condensate of polyalkoxysilane. This polysiloxane-based proton conductive material is preferably made of a polysiloxane containing a compound having at least one of a phosphoric acid group and a sulfonic acid group.
[0017]
[Proton conductive material]
Specifically, the polysiloxane-based proton conductive material includes a silane compound (A) represented by the general formula (1), a silane compound (B) represented by the general formula, if necessary, phosphoric acid and sulfuric acid. Is obtained by subjecting a mixture with at least one kind of acid component (C) to hydrolysis condensation and heat treatment.
[0018]
R² _aSi (OR¹)_4-a・ ・ ・ ・ ・ (1)
[Wherein, R¹Is a monovalent organic group, R²Represents a hydrogen atom, a halogen atom, an alkyl group or an aryl group, and a represents an integer of 0 to 2. ]
R³ _bSi (OR¹)_4-b・ ・ ・ ・ ・ (2)
[Wherein, R¹Is a monovalent organic group, R³Represents a monovalent functional group, and b represents an integer of 1 to 2. ]
The polysiloxane-based proton conductive material includes a silane compound (A) having no organic functional group and having a plurality of alkoxysilyl groups, represented by the general formula (1), and an organic silane compound represented by the general formula (2). Obtained by hydrolyzing and condensing a mixture of a silane compound (B) having a functional group and a plurality of alkoxysilyl groups (if necessary) and an acid component (C) composed of phosphoric acid and / or sulfuric acid. Things. Here, it is considered that the acid component (C) is involved not only as a catalyst component in the hydrolysis-condensation reaction, but also as a condensation component, and is incorporated in the polysiloxane.
[0019]
When the acid component (C) is incorporated into the polysiloxane, the proton conductivity is improved, and the decrease in proton conductivity can be reduced even under high temperature and low humidity conditions. The incorporation of the acidic component (C) into the polysiloxane can be suitably performed by mainly using the silane compound (B). Further, by using the silane compounds (A) and (B) together, a crosslinked structure for obtaining a self-supporting film can be formed in polysiloxane.
[0020]
As described above, the polysiloxane-based proton conductive material is excellent in proton conductivity and has a small decrease in proton conductivity even under high temperature and low humidity conditions. Therefore, an excellent proton conductive membrane can be formed by using this polysiloxane-based proton conductive material. In addition, by using this polysiloxane-based proton conductive material, a self-supporting proton conductive membrane can be obtained. Therefore, a flexible proton conductive sheet can be easily manufactured by using a proton conductive membrane formed using a polysiloxane-based proton conductive material.
[0021]
When both the silane compound (A) and the silane compound (B) are used, the ratio of the amount of the silane compound (A) and the amount of the silane compound (B) used is usually 10 to 70 mol%. , Preferably 20 to 95 mol%, more preferably 25 to 90 mol% (however, (A) + (B) = 100 mol%), and the silane compound (B) is usually 30 to 90 mol%, preferably Is preferably 5 to 80 mol%, more preferably 10 to 75 mol%.
[0022]
The amount of sulfuric acid to be added is generally 0.001 to 3 equivalents, preferably 0.001 to 1.5 equivalents, per 1 equivalent of the alkoxysilyl group of the total of the silane compound (A) and the silane compound (B). The amount of phosphoric acid to be added is generally 0.001 to 3 equivalents, preferably 0.001 to 1.5 equivalents, relative to 1 equivalent of the alkoxysilyl group obtained by adding the silane compound (A) and the silane compound (B). .
[0023]
(Silane compound (A))
The silane compound (A) that can be used in the present invention is a compound represented by the following general formula (1).
[0024]
R² _aSi (OR¹)_4-a・ ・ ・ ・ ・ (1)
[Wherein, R¹Is a monovalent organic group, R²Represents a hydrogen atom, a halogen atom, an alkyl group or an aryl group, and a represents an integer of 0 to 2. ]
R¹Is preferably an organic group selected from an alkyl group, an aryl group, and an arylalkyl group. R²In particular, is preferably an alkyl group or an aryl group, or a group obtained by halogenating them.
[0025]
Specific examples of the silane compound (A) represented by the general formula (1) include methyltrimethoxysilane, methyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyl Triethoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, octyltrimethoxysilane, decyltrimethoxysilane, decyltriethoxysilane, hexadecyltrimethoxysilane, hexadecyltriethoxysilane, octadecyltrimethoxysilane, octadecyltriethoxysilane , Cyclopentyltrimethoxysilane, cyclopentyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, (3-cyclopentadienylpropyl Trimethoxysilane, (3-cyclopentadienylpropyl) triethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, tolyltrimethoxysilane, tolyltriethoxysilane, benzyltrimethoxylan, benzyltriethoxysilane, phenethyltrimethoxy Silane, phenethyltriethoxysilane, bromophenyltrimethoxysilane, bromophenyltriethoxysilane, 3-bromopropyltrimethoxysilane, 3-bromopropyltriethoxysilane, 11-bromoundecyltrimethoxysilane, 3-chloropropyltrimethoxy Silane, 3-chloropropyltriethoxysilane, chlorophenyltrimethoxysilane, chlorophenyltriethoxysilane, chloropropyltrimethoxysilane, Propyltriethoxysilane, chlorophenyltrimethoxysilane, ((chloromethyl) phenylethyl) trimethoxysilane, ((chloromethyl) phenylethyl) triethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) Trialkoxysilanes such as trimethoxysilane, (tridecafluoro-1,1,2,2-tetrahydrooctyl) triethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, 1,3-dimethyl Tetraalkoxysilanes such as tetramethoxydisiloxane, 1,3-dimethyltetraethoxydisiloxane, 1,3-dioctyltetramethoxydiloxane, 1,3-dioctyltetraethoxydiloxane, 1,3-divinyltet Laethoxydisiloxane, bis (trimethoxysilyl) methane, bis (triethoxysilyl) methane, bis (trimethoxysilyl) ethane, bis (triethoxysilyl) ethane, bis (trimethoxysilyl) hexane, bis (triethoxysilyl) ) Hexane, bis (trimethoxysilyl) octane, bis (triethoxysilyl) octane, bis (trimethoxysilyl) nonane, bis (triethoxysilyl) nonane, bis (trimethoxysilyl) ethylene, bis (triethoxysilyl) ethylene And hexaalkoxysilanes such as 1,4-bis (trimethoxysilylethyl) benzene and 1,4-bis (triethoxysilylethyl) benzene.
[0026]
Among these, trialkoxysilane and tetraalkoxysilane are suitable for forming a crosslinked structure for obtaining a self-supporting film as a hybrid material of polysiloxane. Particularly, tetraalkoxysilane is preferable.
[0027]
(Silane compound (B))
The silane compound (B) that can be used in the present invention is a compound represented by the following general formula (2).
[0028]
R³ _bSi (OR¹)_4-b・ ・ ・ ・ ・ (2)
[Wherein, R¹Is a monovalent organic group, R³Represents a monovalent functional group, and b represents an integer of 1 to 2. ]
R¹Is represented by R in the above general formula (1)¹Can be exemplified. R³Are especially vinyl functional groups, allyl functional groups, methacrylic functional groups, acrylic functional groups, epoxy functional groups, mercapto functional groups, ether functional groups, acetoxy functional groups, benzoyl functional groups, and ketone functional groups. Preferred are a functional group, a urea-based functional group, a cyano-based functional group, a thiocyanate-based functional group, a carbamate-based functional group, an acid anhydride-based functional group, and a phosphorus-based functional group.
[0029]
Specific examples of the silane compound (B) represented by the general formula (2) include vinyltrimethoxysilane, vinyltriethoxysilane, butenyltrimethoxysilane, butenyltriethoxysilane, and styrylethyltrimethoxy. Silane, vinyl of styrylethyltriethoxysilane, allyldimethoxysilane, allyldiethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, 2- (chloromethyl) allyltrimethoxysilane, 2- (chloromethyl) allyltriethoxy Allyls such as silane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, acryloxymethyltrimethoxysilane, acryloxymethyltriethoxysilane, 3-methacryloxypropyltrimethoxysilane, -Methacryloxypropyltriethoxysilane, (3-methacryloxypropyl) methyldimethoxysilane, (3-methacryloxypropyl) methyldiethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, ( 3-acryloxypropyl) methyldimethoxysilane, (3-acryloxypropyl) methyldiethoxysilane, O- (methacryloxyethyl) -N- (triethoxysilylpropyl) urethane, O- (methacryloxyethyl)- Methacryls such as N- (trimethoxysilylpropyl) urethane, O- (acryloyloxyethyl) -N- (triethoxysilylpropyl) urethane, O- (acryloyloxyethyl) -N- (trimethoxysilylpropyl) urethane ,Also Acrylic, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4 Epoxy such as -epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 5,6-epoxyhexyltriethoxysilane, and mercaptoethyl Mercapto series such as trimethoxysilane, mercaptoethyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methoxypropyltrimethoxysilane, 3-methoxypropyltrimethoxysilane Such as ethoxysilane, (furfuryloxymethyl) trimethoxysilane, (furfuryloxymethyl) triethoxysilane, 3- (heptafluoroisopropoxy) propyltrimethoxysilane, and 3- (heptafluoroisopropoxy) propyltriethoxysilane Ether type, acetoxy type such as acetoxymethyltrimethoxysilane, acetoxymethyltriethoxysilane, acetoxypropyltrimethoxysilane, acetoxypropyltriethoxysilane, benzoyl type such as benzoyloxypropyltrimethoxysilane, benzoyloxypropyltriethoxysilane, 2 Ketones such as -hydroxy-4- (3-trimethoxypropoxy) diphenylketone and 2-hydroxy-4- (3-triethoxypropoxy) diphenylketone; Urea such as bis (3- (trimethoxysilyl) propyl) urea, bis (3- (triethoxysilyl) propyl) urea, 2-cyanoethyltrimethoxysilane, 2-cyanoethyltriethoxysilane, 2-cyano Cyano-based compounds such as propyltrimethoxysilane, 2-cyanopropyltriethoxysilane, 11-cyanoundecyltrimethoxysilane, and 11-cyanoundecyltriethoxysilane; 3-thiocyanatepropyltrimethoxysilane; 3-thiocyanatepropyltriethoxysilane Carbamates such as (3-trimethoxysilylpropyl) -t-butyl carbamate, (3-trimethoxysilylpropyl) -t-butyl carbamate, 3- (trimethoxysilyl) propyl succinic anhydride; - acid anhydride such as (triethoxysilyl) propyl succinic anhydride, 2- (diphenylphosphino) ethyl trimethoxysilane, 2- and the like phosphorus-based, such as (diphenylphosphino) ethyl triethoxysilane.
[0030]
Among these alkoxysilanes having an organic functional group, vinyl-based, allyl-based, methacryl-based, acrylic-based, and epoxy-based ones that easily incorporate an acid component into the polysiloxane are preferable. Above all, methacrylic, acrylic and epoxy are particularly preferred.
[0031]
[First and second sheet materials]
The first and second sheet members 12, 22 are made of a porous and conductive material. Since the first and second sheet materials 12 and 22 are made of a porous material, the surfaces of the first and second sheet materials 12 and 22 are sufficiently impregnated with the sol-like polysiloxane proton conductive material. be able to. Furthermore, since the first and second sheet materials 12 and 22 are made of a conductive material, when the proton conductive sheet 100 is placed between electrodes of an electrochemical element such as a fuel cell, the conductivity is reduced. Can be enhanced.
[0032]
Specific examples of the material of the first and second sheet materials 12 and 22 include a fired body from polyacrylonitrile, a fired body from pitch, carbon materials such as graphite and expanded graphite, stainless steel, molybdenum, titanium, and the like. Can be exemplified. Although the form of these materials is not particularly limited, fibrous or particulate forms can be exemplified, and fibrous conductive inorganic substances (inorganic conductive fibers), particularly carbon fibers, are preferred.
[0033]
When the first and second sheet materials 12 and 22 are porous conductive sheets using inorganic conductive fibers, any structure of woven fabric or nonwoven fabric can be used. As the woven fabric, plain weave, oblique weave, satin weave, crest weave, stitch weave, and the like are used without particular limitation. In addition, as the nonwoven fabric, a papermaking method, a needle punch method, a spunbond method, a water jet punch method, a melt blow method, and the like are used without particular limitation. Also, a knitted fabric may be used instead of the woven or nonwoven fabric. In these fabrics, particularly when carbon fiber is used, a woven fabric obtained by carbonizing or graphitizing a plain woven fabric using oxidized spun yarn, and oxidized yarn is processed into a nonwoven fabric by a needle punch method, a water jet punch method, or the like. After that, a nonwoven fabric obtained by carbonization or graphitization, a mat nonwoven fabric formed by a papermaking method using a flame-resistant yarn or a graphitized yarn, and the like are preferably used. For example, carbon paper TGP series and SO series manufactured by Electrochem, and carbon cloth manufactured by E-TEK are preferably used.
[0034]
The first and second sheet materials 12 and 22 are not particularly limited, but may be conductive particles such as metal particles such as carbon black, fullerene, carbon nanotube, or platinum as auxiliary materials for improving conductivity. Alternatively, conductive fibers such as carbon fibers and metal fibers can be added.
[0035]
[Production method of proton conductive sheet]
Next, a method for manufacturing the proton conductive sheet 100 will be described below with reference to FIGS.
[0036]
(I) Preparation of sol
First, a sol containing a polysiloxane-based proton conductive material is formed. As described above, the sol is obtained by adding an acidic condensing solvent, if necessary, to a mixture of the silane compound (A) and, if necessary, the silane compound (B) and the acid component (C). Prepared by mixing.
[0037]
As the acidic condensation catalyst, hydrochloric acid, nitric acid, acetic acid, formic acid, phosphoric acid, sulfuric acid and the like can be used, and phosphoric acid and sulfuric acid, which are the acid components (C) incorporated into the polysiloxane, are preferred. The acidity of water is preferably about 0 to 4 in terms of pH. The amount of water added to the mixture of the silane compound (A) and the silane compound (B) is 0.1 to 10 equivalents to 1 equivalent of the total alkoxysilyl group of the silane compounds (A) and (B). Preferably it is 0.2 to 8 equivalents, more preferably 0.5 to 5 equivalents, most preferably 0.5 to 3 equivalents.
[0038]
After a predetermined amount of the acid component (C) is added to a solution containing the silane compound (A) (or the silane compounds (A) and (B)), the reaction system is stirred. It is 100 rpm, preferably 50 to 100 rpm.
[0039]
(II) Formation of proton conducting membrane
Next, a proton conductive membrane 30 is formed (see FIG. 1).
[0040]
After stirring the solution in the above (I), the resulting sol is applied to a substrate to form a film, and then the film is air-dried or vacuum-dried at room temperature to 50 ° C., and then heat-treated. can get. Next, the obtained proton conductive membrane is separated from the substrate. The obtained proton conductive membrane is a self-supporting membrane of a polysiloxane gel. In addition, the heat treatment temperature here varies depending on the material of the sol used, but is usually 50 to 500 ° C, preferably 100 to 300 ° C. The heat treatment time is usually 0.2 to 24 hours, preferably 0.5 to 10 hours.
[0041]
The obtained proton conductive membrane may be composited with an organic polymer. Examples of the organic polymer include an organic polymer-based proton conductive material and a polyimide resin.
[0042]
(III) Coating the surface of the first and second sheet materials with a proton conductive material
Next, the sol obtained in the above (I) is applied to the surfaces of the first and second sheet materials 12 and 22 (see FIG. 2). As described above, the first and second sheet materials 12, 22 are made of a porous material. For this reason, as shown in FIG. 2, the sol obtained in the above (I) is applied to the surfaces of the first and second sheet materials 12 and 22 so that the first and second sheet materials 12 and 22 are coated. , 22 enter the sol. Thereby, the sol can be reliably held on the first and second sheet materials 12 and 22.
[0043]
Here, the case where the sol as the raw material of the proton conductive membrane 30 and the gel applied to the surfaces of the first and second sheet materials 12 and 22 are the same material has been described. Different materials may be used as long as there is no problem in the properties.
[0044]
(IV) Compression bonding of first and second sheet materials and proton conductive membrane
Next, the sol is applied and pressed between the first and second sheet materials 12 and 22 with the proton conductive membrane 30 interposed therebetween (see FIG. 3). Specifically, the first and second sheet materials 12 and 22 and the first and second sheet materials 12 and 22 are bonded to the proton conductive membrane 30 while the sol-coated surfaces of the first and second sheet materials 12 and 22 are joined to the proton conductive membrane 30. The conductive film 30 is pressed.
[0045]
The method for the pressure bonding is not particularly limited, and examples thereof include a hot press method. The pressure at the time of pressing and the time required for pressing can be appropriately set depending on the materials and thickness of the proton conductive membrane 30 and the sol.
[0046]
Through the above steps, a proton conductive sheet 100 including the first and second sheet materials 12 and 22 and the proton conductive membrane 30 sandwiched between the first and second sheet materials 12 and 22 is obtained. (See FIG. 1).
[0047]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples, but the present invention is not limited to the following Examples.
[0048]
Starting materials include 3-methacryloxypropyltrimethoxysilane (CH₂= C (CH₃)-(CH₂)₃-Si (OCH₃)₃(Manufactured by Chisso Corporation, hereinafter abbreviated as TMSPM), tetramethoxysilane (Si (OCH₃)₄) (Tokyo Kasei Kogyo Co., Ltd .; hereinafter abbreviated as TMOS), tetraethoxysilane (Si (OCH₂CH₃) ₄) (Manufactured by Tokyo Chemical Industry Co., Ltd .; hereinafter abbreviated as TEOS), ethyl alcohol (manufactured by Wako Pure Chemical Industries, Ltd.), sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.), and phosphoric acid (manufactured by Wako Pure Chemical Industries, Ltd.) Using. The water used was distilled water of ion-exchanged water.
[0049]
[Example 1]
(I) Preparation of sol containing proton conducting material
1.5 mol (372.5 g) of TMSPM and 1 mol (152.2 g) of TMOS were mixed at room temperature for 10 minutes. An aqueous solution consisting of 0.0125 mol (1.23 g) of concentrated sulfuric acid and 7.5 mol (135 g) of water was added thereto, and the mixture was stirred at room temperature for 2 hours to prepare a sol containing a proton conductive material.
[0050]
(II) Formation of proton conducting membrane
The sol obtained in the above (I) is cast on a Teflon (registered trademark) petri dish, allowed to stand at room temperature for 1 hour, dried at 50 ° C. for one day, and further heat-treated at 150 ° C. for 5 hours. Was performed. As a result, a proton conductive membrane made of a transparent gel was obtained. This proton conductive membrane was a self-supporting membrane having a thickness of 100 μm, and no crack was detected with the naked eye.
[0051]
(III) Coating the surface of the first and second sheet materials with a proton conductive material
The sol obtained in the above (I) was applied to the surfaces of the first and second sheet materials. In this example, a carbon material containing platinum (carbon paper carrying platinum (Teflon (registered trademark) -treated by Electrochem)) was used as the first and second sheet materials. In this carbon paper, the supported amount of platinum is 1 mg / cm.²Met.
[0052]
(IV) Formation of proton conductive sheet
The proton conductive membrane obtained in (II) is sandwiched between the first and second sheet materials coated with the sol in (III). It was pressed by a hot press for a time. Thus, the proton conductive sheet of Example 1 was obtained.
[0053]
The obtained proton conductive sheet was set on a fuel cell for testing, and the relationship between output current and battery voltage was examined. FIG. 4 shows a schematic diagram of the test fuel cell 300. The fuel cell 300 shown in FIG. The fuel cell 200 includes the electrodes 20 and 21 and the proton conductive sheet 100. Here, the proton conductive sheet 100 functions as an electrolyte membrane of the fuel cell 200. Specifically, as shown in FIG. 4, the proton conductive sheet 100 is sandwiched between the electrodes 20 and 21. The temperature of the fuel cell 200 is adjusted by a heater (not shown).
[0054]
In the fuel cell 200, hydrogen is supplied to the electrode (anode) 20 and air is supplied to the electrode (cathode) 21. That is, the fuel cell 300 is a fuel cell using hydrogen as fuel.
[0055]
As the electrodes 20 and 21, a gas diffusion electrode manufactured by E-Tech (platinum loading 0.35 mg / cm) was used.²) Was used. The fuel cell 200 was formed by sandwiching the proton conductive sheet 100 obtained in the above step between the electrodes 20 and 21 and hot pressing at a temperature of 150 ° C.
[0056]
Specifically, as shown in FIG. 4, the fuel cell 300 includes a fuel cell 200, and stainless steel blocks 29 and 39 sandwiching the fuel cell 200. The stainless steel block 29 is H₂Gas inlet 23, fuel chamber 24, and H₂It includes a gas discharge hole 25. The stainless steel block 39 is₂Gas inlet 26, oxygen chamber 27, and O₂It includes a gas exhaust hole 28. The entire fuel cell 300 is fixed by fastening rods 31 and 32 made of electrically insulating fiber reinforced plastic. In FIG. 4, 33 is H₂The drain of O, 34 is an anode terminal, and 35 is a cathode terminal.
[0057]
In the test, under the condition of a temperature of 130 ° C. and a relative humidity (RH) of 10%, hydrogen (pressurized to 3 atm) was applied to the electrode (fuel electrode) 20 and 5 atm was applied to the electrode (air electrode) 21. The relationship between the output current and the battery voltage was examined through air. As a result, in this test fuel cell 300, 400 mA / cm²When the current was taken out, the battery voltage was maintained at 0.7 V or more, indicating that the battery exhibited excellent high-output characteristics. As described above, it was found that by using the proton conductive sheet of this example, a fuel cell having excellent characteristics was obtained.
[0058]
[Example 2]
1 mol (208.3 g) of TEOS and 8 mol (368.6 g) of ethanol were mixed, and 4 mol of water prepared under acidic conditions of pH 0.3 using 0.01 mol (0.09 g) of hydrochloric acid separately. (72 g) and stirred at room temperature for 10 minutes. To this, 0.5 mol (49 g) of phosphoric acid was added, and the mixture was stirred at room temperature for 3 hours to prepare a sol containing a proton conductive material.
[0059]
The obtained sol was cast on a Teflon (registered trademark) petri dish, allowed to stand at room temperature for 1 hour, dried at 50 ° C. for 24 hours, and further heat-treated at 300 ° C. for 5 hours. As a result, a proton conductive membrane made of a transparent gel was obtained. This proton conductive membrane was a self-supporting membrane having a thickness of 100 μm, and no crack was detected with the naked eye.
[0060]
Subsequent steps were performed in the same manner as in Example 1. As a result, a proton conductive sheet of this example was obtained. Further, a fuel cell using the proton conductive sheet obtained in this example was evaluated under the same method and conditions as in Example 1. As a result, in the fuel cell using the proton conductive sheet of this example, 400 mA / cm²When the current was taken out, the battery voltage was maintained at 0.7 V or more, indicating that the battery exhibited excellent high-output characteristics. As described above, it was found that by using the proton conductive sheet of this example, a fuel cell having excellent characteristics was obtained.
[0061]
In the examples, a fuel cell was described as an electrochemical element using a proton conductive sheet.However, the present invention also relates to an electrochemical element not described in the examples, such as a pH sensor and an electric double layer capacitor. It goes without saying that a proton conductive sheet can be applied.
[0062]
【The invention's effect】
According to the method for producing a proton conductive sheet of the present invention, a proton conductive sheet having high proton conductivity and excellent flexibility can be efficiently produced. In addition, a large-area proton conductive sheet can be manufactured at low cost.
[0063]
Further, after the sol is applied to the surfaces of the first and second sheet materials, the sol is pressed in a state where the proton conductive film is sandwiched between the sheet materials, so that the close contact between the sheet material and the proton conductive film is achieved. A proton conductive sheet having excellent properties can be obtained. Further, by using a porous conductive sheet as the first and second sheet materials, a sufficient amount of the sol can be impregnated on the surfaces of the first and second sheet materials, and the proton conductivity can be improved. The conductivity of the conductive sheet can be increased.
[0064]
Further, the proton conductive sheet obtained by the production method of the present invention is useful as an electrolyte membrane for various electrochemical devices such as a fuel cell, a capacitor, and an electrochromic display device.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically illustrating a proton conductive sheet obtained by a manufacturing method according to an embodiment.
FIG. 2 is a cross-sectional view schematically showing one manufacturing process of the proton conductive sheet shown in FIG.
FIG. 3 is a cross-sectional view schematically showing one manufacturing process of the proton conductive sheet shown in FIG.
FIG. 4 is a diagram schematically showing an example of a fuel cell using the proton conductive sheet shown in FIG.
[Explanation of symbols]
12 First sheet material
14,24 Proton conductive material
14a, 24a sol
20 electrodes (anode)
21 electrodes (cathode)
22 Second sheet material
23 H₂Gas inlet
25H₂Gas outlet
26 O₂Gas inlet
27 Oxygen chamber
28 O₂Gas outlet
30 Proton conductive membrane
31, 32 Tightening rod
33 H₂O drain
34 Anode terminal
35 Cathode terminal
37 Fuel Chamber
100 proton conductive sheet
200 fuel cell
300 fuel cell

Claims (4)

Prepare a sol containing a polysiloxane-based proton conductive material,
By performing a heat treatment after forming the sol, a proton conductive membrane is formed,
Coating the sol on the surface of a porous and conductive first and second sheet material,
Pressing the sol coated with the proton conductive membrane sandwiched between the first and second sheet materials,
A method for producing a proton conductive sheet, comprising: In claim 1,
A method for manufacturing a proton conductive sheet, wherein at least one of the first and second sheet members is made of a carbon material containing platinum. In claim 1 or 2,
The method for producing a proton conductive sheet, wherein the proton conductive membrane is a hydrolyzed condensate of a polyalkoxysilane and contains a compound having at least one of a phosphate group and a sulfonic acid group. In any one of claims 1 to 3,
The method for producing a proton conductive sheet, wherein the sol further contains an organic polymer.

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