JP2007066764A - Membrane electrode assembly and fuel cell using the same - Google Patents

Abstract

（Ｘは１７族元素のいずれかであり、ｙは正の実数を示し、１．０≦ｙ≦２．３）前記多孔質体はポリテトラフルオロエチレン等のポリマー、またはＡｌ_２Ｏ_３等の無機多孔質体から選択される少なくとも一種である。
【選択図】 なしPROBLEM TO BE SOLVED: To provide a membrane electrode assembly having an electrolyte membrane made of a porous support impregnated with a room temperature molten salt, and a fuel cell using the membrane electrode assembly, and a membrane electrode assembly excellent in power generation performance. .
A membrane electrode assembly in which electrodes are arranged on both sides of an electrolyte membrane, wherein the electrolyte membrane includes an electrolyte material composed of a cation and an anion, and a porous support. It is. The electrolyte material is a room temperature molten salt represented by the following chemical formula (I):

(X is one of group 17 elements, y represents a positive real number, 1.0 ≦ y ≦ 2.3) The porous body is a polymer such as polytetrafluoroethylene, Al ₂ O ₃ or the like. It is at least one selected from inorganic porous bodies.
[Selection figure] None

Description

  The present invention relates to a membrane electrode assembly having an electrolyte membrane made of a porous support impregnated with a room temperature molten salt, and a fuel cell using the membrane electrode assembly.

  In recent years, fuel cells have attracted attention as power sources for electric vehicles and stationary power sources in response to social demands and trends against the background of energy and environmental problems. Fuel cells are classified into various types depending on the type of electrolyte, the type of electrode, and the like, and representative types include alkaline type, phosphoric acid type, molten carbonate type, solid electrolyte type, and solid polymer type. Among them, a polymer electrolyte fuel cell that can operate at a low temperature (usually 100 ° C. or less) attracts attention, and in recent years, development and practical application as a low-pollution power source for automobiles is progressing.

  The polymer electrolyte fuel cell generally has a structure in which a membrane electrode assembly (MEA) is sandwiched between separators. In MEA, an electrolyte membrane is sandwiched between a pair of electrodes, that is, a fuel electrode and an oxygen electrode. The electrode includes an electrode catalyst and a solid polymer electrolyte, and has at least an electrode catalyst layer having a porous structure in order to diffuse a reaction gas supplied from the outside.

  In general, a perfluorocarbon sulfonic acid (PFSA) membrane or the like is used as an electrolyte membrane of a conventional polymer electrolyte fuel cell, but water contained in the PFSA membrane serves as a proton conduction path. Cannot be used under dry conditions or operating conditions above 100 ° C or below freezing. In order to improve proton conductivity in such a dry state, an attempt is made to achieve high temperature operation by adding a proton conductivity imparting agent to an organic polymer (Patent Document 1), and a silica-dispersed perfluorosulfonic acid membrane is used. A method (Patent Document 2), a method using an inorganic-organic composite film (Patent Document 3), a method using a phosphate-doped graft film (Patent Document 4), and the like are performed.

  On the other hand, various devices have also been tried using room temperature molten salts as electrolytes. A room temperature molten salt has (i) no or very low vapor pressure, (ii) non-flammability or flame retardant, (iii) ionic conductivity, (iv) higher decomposition voltage than water, (V) It has excellent characteristics as an electrolyte such as a liquid temperature range wider than that of water. These characteristics are suitable for fuel cell applications where high temperature of 100 ° C. or higher and non-humidified operation is desired, and proton conductors with specific compositions have been developed as those that can be used in electrochemical devices such as batteries and electrolysis. ing. For example, there is a proton conductor comprising an ionic liquid and a proton donor, the ionic liquid comprising a quaternary ammonium and an anion, and the proton donor being a Bronsted acid, which is used as an electrolyte for a fuel cell ( Patent Document 5).

  A preferred ionic liquid in Patent Document 5 is EMITFSI, and its structure is shown in the following formula.

  Moreover, the proton donor used suitably by this patent document 5 is HTfO, The structure is shown in a following formula.

In the system using the ionic liquid and Bronsted acid shown in Patent Document 5, HTfO acts as a proton donor and conducts protons, and the proton conductivity at this time is about 10 ⁻² Scm ⁻¹ at room temperature. It is said that.

  On the other hand, even in a room temperature molten salt to which a proton donor such as Bronsted acid is not added, proton conductivity has been confirmed for those having a certain structural formula. For example, proton conductivity has been confirmed for N, N-HImTFSI shown below (Non-Patent Document 1).

Furthermore, proton conductivity has also been confirmed in N, N-HImBF ₄ shown below (Non-Patent Document 1).

The room temperature molten salt does not contain a proton donor such as HTfO as in Patent Document 5 and does not contain a proton in the system, but is caused to conduct proton conduction. The mechanism of proton conductivity is considered to be that H bonded to N of the imidazolium cation has self-dissociation ability and exhibits proton conductivity. The neutral room temperature molten salt also has a proton conductivity of about room temperature. 10 ⁻² Scm ⁻¹ .
JP 2001-35509 A JP-A-6-1111827 JP 2000-90946 A JP 2001-213987 A JP 2003-123791 A New Energy and Industrial Technology Development Organization 2002 Industrial Technology Research Grants Research Results Report-Development of Composite Electrolytes for Medium Temperature Fuel Cells Operating under No Humidity Conditions

However, the proton conductivity in the system in which HTfO is added to EMITFSI shown in Patent Document 5 and the N, N-HIm-based room temperature molten salt shown in Non-Patent Document 1 is 10 ⁻² Scm ⁻¹ (room temperature) as described above. Therefore, the obtained fuel cell may not have sufficiently high power generation performance.

  Furthermore, when the room temperature molten salt is used in a liquid state as an electrolyte for a fuel cell, there is a problem that the output density of the obtained fuel cell is small.

  Accordingly, an object of the present invention is to provide a membrane electrode assembly having excellent power generation performance.

  As a result of examining the membrane electrode assembly using a room temperature molten salt as an electrolyte, the present inventors have improved the power generation performance of the membrane electrode assembly obtained by impregnating the porous support with the room temperature molten salt. I found out.

That is, the present invention is a membrane electrode assembly in which electrodes are arranged on both sides of an electrolyte membrane,
The above-mentioned problem is solved by a membrane / electrode assembly in which the electrolyte membrane includes an electrolyte material composed of a cation and an anion and a porous support.

  In the present invention, it is possible to provide a membrane / electrode assembly with greatly improved power generation performance by using a room temperature molten salt as an electrolyte membrane.

The first of the present invention is a membrane electrode assembly in which electrodes are arranged on both sides of an electrolyte membrane,
The electrolyte membrane is a membrane / electrode assembly including an electrolyte material composed of a cation and an anion and a porous support.

  The electrolyte membrane used for the membrane electrode assembly of the present invention has a porous support in addition to the room temperature molten salt. As a result, it becomes possible to use room temperature molten salt as a self-supporting immobilization membrane, and it is possible to prevent the pores in the electrode from being blocked by the movement of the electrolyte in the liquid state within the membrane electrode assembly, and It is possible to suppress leakage of the contents of the joined body. Thereby, it becomes possible to provide a membrane electrode assembly excellent in power generation performance and reliability.

  Furthermore, since the room temperature molten salt is used as the electrolyte in the membrane electrode assembly, high power generation performance can be maintained even when the temperature of the membrane electrode assembly is 120 ° C. or higher. The increase in the temperature of the membrane electrode assembly can be expected to reduce the activation overvoltage of the electrode catalyst. That is, the amount of electrode catalyst used can be reduced by improving the catalytic activity by increasing the temperature. Therefore, compared to a conventional perfluorocarbon sulfonic acid film such as Nafion (registered trademark), it is possible to reduce the amount of noble metal such as expensive platinum used, and to suppress the cost of the membrane electrode assembly. .

  Hereinafter, the membrane electrode assembly of the present invention will be described in more detail.

<Electrolyte membrane>
As described above, the electrolyte membrane used in the membrane electrode assembly of the present invention includes an electrolyte material composed of a cation and an anion, and a porous support.

  Examples of the electrolyte material include room temperature molten salts and hydrocarbon electrolytes. Especially, since it has the characteristic outstanding as electrolyte, it is preferable to use normal temperature molten salt.

  The room temperature molten salt preferably has a melting point of 200 ° C. or higher and contains a cation and an anion.

  In the present invention, as the room temperature molten salt, one not containing an anion represented by the following chemical formula (I) is used.

(X is any of group 17 elements, y represents a positive real number, 1.0 ≦ y ≦ 2.3)
Below, the cation and the anion which comprise the normal temperature molten salt used for the ionic conductor of this invention are demonstrated in detail, giving a specific example. In the present invention, the following cations and anions can be used in appropriate combinations.

  Examples of the molecular cation that is a kind of the cation include, for example, an imidazolium derivative cation, and more specifically, a monosubstituted imidazolium derivative cation represented by the following formula (1):

(Wherein R ₁₁ represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group).

  Specific examples of the hydrocarbon group include a methyl group and a butyl group.

  In addition, a disubstituted imidazolium derivative cation represented by the following formula (2) (Distributed Imidazol Derivatives Cation);

(In the formula, R ₂₁ and R ₂₂ may be the same or different and each represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group. .).

Examples of R ₂₁ and R ₂₂ include any combination of the same groups as those described above for R _11, and in addition, ethyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group , Tetradecyl group, hexadecyl group, octadecyl group, benzyl group, γ-phenylpropyl group, and the like.

As specific examples of typical combinations of these groups, R ₂₁ is a methyl group, and R ₂₂ is a methyl group, ethyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group. , Tetradecyl group, hexadecyl group, octadecyl group, benzyl group, and γ-phenylpropyl group, and those in which R ₂₁ is an ethyl group and R ₂₂ is a butyl group.

  Furthermore, a trisubstituted imidazolium derivative cation represented by the following formula (3) (Tristubulated Imidazol Derivatives Cation);

(In the formula, R _{31 to} R ₃₃ may be the same or different and each represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group. .).

Then, as the R ₃₁ to R _33, there may be mentioned those obtained by arbitrarily combining the same as R ₁₁ mentioned above, other ethyl group, a propyl group, a hexyl group, and the like hexadecyl .

Specific examples of typical combinations of these groups include those in which R ₃₁ is an ethyl group, R ₃₂ and R ₃₃ are methyl groups, R ₃₁ is a propyl group, and R ₃₂ and R ₃₃ are A methyl group, R ₃₁ is a butyl group, R ₃₂ and R ₃₃ are methyl groups, R ₃₁ is a hexyl group, R ₃₂ and R ₃₃ are methyl groups, R ₃₁ is hexadecyl And a group in which R ₃₂ and R ₃₃ are methyl groups.

  Moreover, the pyridinium derivative cation (Pyridinium Derivatives Cation) represented by following formula (4);

(In the formula, R _{41 to} R ₄₄ may be the same or different, and are a hydrogen atom or a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably a C 1-20 alkyl group or arylalkyl. Group).

Then, as the R ₄₁ to R _44, there may be mentioned those obtained by arbitrarily combining the same as R ₁₁ mentioned above, other a hydrogen atom, an ethyl group, a hexyl group, and octyl group .

Specific examples of typical combinations of these groups include those in which R ₄₁ is an ethyl group, R _{42 to} R ₄₄ are hydrogen atoms, R ₄₁ is a butyl group, and R _{42 to} R ₄₄ are A hydrogen atom, R ₄₂ and R ₄₃ are hydrogen atoms and R ₄₄ is a methyl group, R ₄₂ and R ₄₄ are hydrogen atoms and R ₄₃ is a methyl group, R ₄₂ and R ₄₃ are A methyl group and R ₄₄ is a hydrogen atom, R ₄₂ and R ₄₄ are methyl groups and R ₄₃ is a hydrogen atom, R ₄₂ and R ₄₃ are hydrogen atoms and R ₄₄ is an ethyl group , R ₄₁ is a hexyl group, R _{42 to} R ₄₄ are hydrogen atoms, R ₄₂ and R ₄₃ are hydrogen atoms and R ₄₄ is a methyl group, R ₄₂ and R ₄₄ are hydrogen atoms R ₄₃ is der methyl _{Things, R 41} is an octyl _group, objects or _{R 42} and _{R 43} as R 42 _{to R 44} is a hydrogen atom is a hydrogen atom _{R 44} is a methyl _{group, R 42} and _{R 44} are hydrogen atoms And _R43 is a methyl group.

  Further, a pyrrolidinium derivative cation represented by the following formula (5) (Pyrrolidinium Derivatives Cation);

(In the formula, R ₅₁ and R ₅₂ may be the same or different and each represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group. .).

Examples of R ₅₁ and R ₅₂ include those obtained by arbitrarily combining the same as R ₁₁ described above, and other examples include an ethyl group, a propyl group, a hexyl group, and an octyl group. .

Specific examples of typical combinations of these groups include those in which R ₅₁ is a methyl group, R ₅₂ is a methyl group, an ethyl group, a butyl group, or a hexyl group. , An octyl group, R ₅₁ is an ethyl group, R ₅₂ is a butyl group, and R ₅₁ and R ₅₂ are a propyl group, a butyl group, and a hexyl group.

  Moreover, the ammonium derivative cation (Ammonium Derivatives Cation) represented by following formula (6);

(In the formula, R _{61 to} R ₆₄ may be the same or different and each represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group. .).

Then, as the R ₆₁ to R _64, there may be mentioned those obtained by arbitrarily combining the same as R ₁₁ mentioned above, other ethyl group, and octyl group.

Specific examples of typical combinations of these groups include those in which R _{61 to} R ₆₄ are a methyl group, an ethyl group, a butyl group, R ₆₁ is a methyl group, and R ₆₂ to R ₆₄ can be exemplified such as an octyl group.

Furthermore, a phosphonium derivative cation (Phosphonium) represented by the following formula (7):
Derivatives Cation);

(In the formula, R _{71 to} R ₇₄ may be the same or different and each represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group. .).

Then, as the R ₇₁ to R _74, there may be mentioned those obtained by combining arbitrarily the same as R ₁₁ mentioned above, other ethyl group, an isobutyl group, a hexyl group, an octyl group, a tetradecyl group, a hexadecyl group , Phenyl group, benzyl group and the like.

As specific examples of typical combinations of these groups, R ₇₁ is a methyl group, R _{72 to} R ₇₄ are butyl groups or isobutyl groups, R ₇₁ is an ethyl group, R _{72 to} R ₇₄ are butyl groups, R _{71 to} R ₇₄ are butyl groups or octyl groups, R ₇₁ is a tetradecyl group, and R _{72 to} R ₇₄ are butyl groups, Examples thereof include a hexyl group, R ₇₁ is a hexadecyl group, R _{72 to} R ₇₄ are butyl groups, R ₇₁ is a benzyl group, and R _{72 to} R ₇₄ are phenyl groups. it can.

  Further, a guanidinium derivative cation represented by the following formula (8) (Guanidinium Derivatives Cation);

(In the formula, R _{81 to} R ₈₆ may be the same or different and are each a hydrogen atom or a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably a C 1-20 alkyl group or arylalkyl. Group).

Then, as the R ₈₁ to R _86, there may be mentioned those obtained by arbitrarily combining the same as R ₁₁ mentioned above, other a hydrogen atom, an ethyl group, a propyl group, and the like isopropyl .

Specific examples of typical combinations of these groups include those in which all of R _{81 to} R ₈₆ are hydrogen atoms or methyl groups, R ₈₁ is an ethyl group, and R _{82 to} R ₈₅ are methyl groups. , R ₈₆ is a hydrogen atom, R ₈₁ is an isopropyl group, R _{82 to} R ₈₅ are methyl groups, R ₈₆ is a hydrogen atom, R ₈₁ is a propyl group, and R _{82 to} R ₈₆ are methyl groups The thing etc. can be mentioned.

  Furthermore, an isouronium derivative cation (Isouronium Derivatives Cation) represented by the following formula (9);

(In the formula, R _{91 to} R ₉₅ may be the same or different, and are a hydrogen atom or a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably a C 1-20 alkyl group or arylalkyl. And A ₉ represents an oxygen atom or a sulfur atom.).

Then, as the R ₉₁ to R _95, there may be mentioned any combination of the the same as R ₁₁ mentioned above, other a hydrogen atom, and the like ethyl.

Specific examples of typical combinations of these groups include those in which A ₉ is an oxygen atom (O) and all of R _{91 to} R ₉₅ are methyl groups, R ₉₁ is an ethyl group, R ₉₂ those to R ₉₅ is a methyl group, _{a 9} is a sulfur atom _(S), and the like as _{R 91} is an ethyl _group, R 92 _{to R 95} is a methyl group.

  On the other hand, as a molecular anion which is a kind of anion, for example, sulfate anion represented by the following formula (10) (Sulfates anion);

(Wherein R ₁₀₁ represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group having 1 to 20 carbon atoms or an arylalkyl group).

Then, as R ₁₀₁ may include the same as R ₁₁ mentioned above, other ethyl group, a hexyl group, and octyl group.

Further, typical examples include those in which R ₁₀₁ is a methyl group, an ethyl group, a butyl group, a hexyl group, or an octyl group.

  Moreover, the sulfonate ester anion (Sulfonates anion) represented by following formula (11);

(Wherein R ₁₁₁ represents a monovalent organic group, preferably a monovalent hydrocarbon group, more preferably an alkyl group or arylalkyl group having 1 to 20 carbon atoms, and further a fluorine-substituted product thereof). be able to.

As typical examples, R ₁₁₁ is a fluorine-substituted methyl group (corresponding to a trifluoromethanesulfonate anion), and further a p-tolyl group (corresponding to a p-toluenesulfonic acid anion). Some can be mentioned.

  Further, an amide anion or an imide anion represented by the following formulas (12) to (14);

Can be mentioned.

  The amide anion and imide anion are not necessarily limited to these.

  In addition, a methane anion represented by the following formula (15) or (16);

Can be mentioned.

  The methane anion is not necessarily limited to these.

  Moreover, the boron-containing compound anion represented by the following formulas (17) to (22);

Can be mentioned.

  Note that the boron-containing compound anion is not necessarily limited thereto.

  Furthermore, phosphorus-containing compound anions represented by the following formulas (23) to (29);

Can be mentioned.

  The phosphorus-containing compound anion is not necessarily limited to these.

  And a carboxylate anion represented by the following formula (30) or (31):

Can be mentioned.

  The carboxylate anion is not necessarily limited to these.

  And a metal element-containing anion represented by the following formula (32) or (33):

Can be mentioned.

  The metal element-containing anion is not necessarily limited to these.

On the other hand, is not a molecular anion, fluorine anion is a halide anion (Halogenides Anion) as another anionic component [F ^-] and chloride anion [Cl ^-], bromide [Br ^-], iodine anion [I ^-] Can also be mentioned.

  The room temperature molten salt of the present invention preferably contains a combination or mixture of the above-described cation and anion.

  In the electrolyte membrane used for the membrane electrode assembly of the present invention, it is preferable to impregnate the porous support with the above-mentioned room temperature molten salt. Thereby, the strength of the electrolyte membrane can be improved, and the reliability of the obtained membrane electrode assembly can be further improved.

  The porosity of the porous support is preferably 5 to 95%, more preferably 30 to 80%. If the porosity is less than 5%, the amount of electrolyte filling the porous support may not be sufficiently obtained, and the power generation performance of the membrane electrode assembly may be deteriorated. There is a possibility that the strength of the electrolyte membrane cannot be sufficiently improved by the body.

  The thickness of the porous support is preferably 10 μm to 200 μm, more preferably 20 to 90 μm. If the thickness is less than 10 μm, the strength of the electrolyte membrane may not be sufficiently improved by the porous support. If the thickness exceeds 200 μm, the proton conductivity decreases, and the membrane electrode assembly has a power generation performance. There is a risk of lowering.

  Specifically, the porous support preferably includes at least one selected from the group consisting of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene, polypropylene, polyamide, and polyimide. It is done. According to these, a porous support having sufficient strength can be obtained.

  Specifically, an inorganic porous body is preferably used in addition to the above-mentioned porous support. If it contains an inorganic porous body or a part of the inorganic porous body, a self-supporting electrolyte membrane containing a room temperature molten salt can be obtained, and the power generation performance of the membrane electrode assembly can be improved.

Specifically as the inorganic porous _{material, Al 2 O 3, SiO 2} , TiO 2, and consist of at least one selected from the group consisting of ZrO ₂ are preferably exemplified.

  The electrolyte membrane preferably further contains a polymer. That is, in addition to the above-mentioned room temperature molten salt, it is preferable to impregnate a porous support with a polymer and use it as an electrolyte membrane. According to the polymer, the room temperature molten salt can be reliably fixed in the porous support, and the reliability and power generation performance of the membrane electrode assembly can be improved.

  Such an electrolyte membrane is preferably as described in the method for producing a membrane electrode assembly of the present invention to be described later, but includes a solution containing a room temperature molten salt, a monomer that can constitute the polymer, and a polymerization initiator. It is obtained by polymerizing after impregnating the porous support.

  As the polymer, specifically, at least one polymer selected from the group consisting of polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethyl methacrylate, and polyvinylidene fluoride, and / or an acrylic acid monomer, methacrylic monomer, Preferred is a polymer of at least one monomer selected from the group consisting of acid monomers, acrylamide monomers, allyl monomers, styrene monomers, and epoxy monomers. These polymers and polymers may be composed of only one kind of the polymer or the monomer, or may be a mixture of two or more kinds of the polymer and the monomer. According to these polymers and polymers, the effect that the room temperature molten salt can be polymerized and immobilized as a film can be obtained.

  Examples of the (meth) acrylic acid monomer include 2-hydroxylethyl methacrylate, (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, 2- (meth) acryloylethanesulfonic acid, 2- ( (Meth) acryloylpropanesulfonic acid, 2- (meth) acrylamide-2-methylpropanesulfonic acid, vinylsulfonic acid, styrenesulfonic acid, (meth) acrylamide, N-substituted (meth) acrylamide, 2-hydroxypropyl (meth) acrylate Monomers such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, I like the salt And the like properly. Preferred examples of the acrylamide monomer include acrylamide and N, N-dimethylacrylamide (DMAA). Preferable examples of the allylic monomer include allyl, allylamine, triallyl isocyanurate and the like. Preferred examples of the styrenic monomer include styrene, methyl styrene, and trifluorostyrene. Preferred examples of the epoxy monomer include bisphenol fluorenediglycidyl ether and bisphenoxyethanol fluorenediglycidyl ether. Furthermore, as a hydrophilic monomer, methacrylic acid (MCAA), acrylic acid (AAC), N-vinyl-2-pyrrolidone (NVP), etc. are preferably mentioned in addition to 2-hydroxyethyl methacrylate.

  When an acrylate is used as the monomer, a monovalent salt of acrylic acid selected from alkali metal salts, ammonium salts, and amine salts of acrylic acid is preferable from the viewpoint of stably fixing a room temperature molten salt. More preferred are alkali metal acrylates, and particularly preferred are acrylates selected from sodium salts, lithium salts, and potassium salts.

  As said polymer, the polymer of the monomer component which has 2-hydroxyl ethyl methacrylate (HEMA) as a main component is mentioned preferably. According to the polymer using HEMA as a monomer, not only can the room temperature molten salt be fixed in the membrane electrode assembly, but also the power generation performance of the obtained membrane electrode assembly can be further improved. Although the reason for improving the power generation performance is not clear, it is conceivable to reduce the activation overvoltage by improving the oxygen permeability.

  In the polymer of monomer components mainly composed of HEMA, the content of HEMA is 10% by weight or more, preferably 30 to 60% by weight, based on all polymer components. By setting the content of HEMA within the above range, an excellent effect of HEMA can be exhibited.

  In the electrolyte used for the membrane electrode assembly of the present invention, the ratio of the mole of the room temperature molten salt to the total mole ratio of the monomers constituting the polymer (N = room temperature molten salt / monomer) is preferably 0.00. 3 ≦ N ≦ 0.7, more preferably 0.45 ≦ N ≦ 0.6. If the molar ratio is less than 0.3, the hydrogen mobility may be extremely lowered, and if it is 0.7 or more, the polymerization may not proceed sufficiently.

The thickness of the electrolyte membrane may be appropriately determined in consideration of the characteristics of the obtained membrane electrode assembly, but is preferably 10 to 200 μm, more preferably 20 to 90 μm. It is preferably 10 μm or more from the viewpoint of strength during film formation and durability during operation of the membrane electrode assembly, and is preferably 200 μm or less from the viewpoint of output characteristics during MEA operation.

<Electrode>
The electrode used for the membrane electrode assembly of the present invention has at least an electrode catalyst layer containing the above-described electrolyte material containing a cation and an anion and an electrode catalyst.

  Since the same electrolyte material as that described above in the electrolyte membrane is used as the electrolyte material, detailed description thereof is omitted here.

  The electrode catalyst can be used without particular limitation as long as it is an electrode catalyst used in conventional general fuel cells such as a polymer electrolyte fuel cell. The electrode catalyst includes at least a catalyst component that can promote an electrode reaction.

  The catalyst component used in the cathode catalyst layer is not particularly limited as long as it has a catalytic action for the oxygen reduction reaction, and a known catalyst can be used in the same manner. Further, the catalyst component used in the anode catalyst layer is not particularly limited as long as it has a catalytic action for the oxidation reaction of hydrogen, and a known catalyst can be used in the same manner. Specifically, it is selected from platinum, ruthenium, iridium, rhodium, palladium, osmium, tungsten, lead, iron, chromium, cobalt, nickel, manganese, vanadium, molybdenum, gallium, aluminum and the like, and alloys thereof. Is done.

  The shape and size of the catalyst component are not particularly limited, and the same shape and size as known catalyst components can be used, but the catalyst component is preferably granular. At this time, the smaller the average particle diameter of the catalyst particles, the higher the catalytic activity because the effective electrode area where the electrochemical reaction proceeds increases, which is preferable. However, in practice, if the average particle diameter is too small, the catalytic activity decreases. The phenomenon is seen. Accordingly, the average particle size of the catalyst particles is preferably 1 to 30 nm, more preferably 1.5 to 20 nm, even more preferably 2 to 10 nm, and particularly preferably 2 to 5 nm. The “average particle diameter of the catalyst particles” in the present invention is the average value of the particle diameter of the catalyst component determined from the crystallite diameter or transmission electron microscope image obtained from the half-value width of the diffraction peak of the catalyst component in X-ray diffraction. Can be measured.

  The electrode catalyst may further contain a conductive carrier. By supporting the above-described catalyst component on the conductive carrier, it becomes possible to improve the dispersibility of the catalyst component and improve the catalytic activity of the electrode catalyst.

  The conductive carrier may have any specific surface area for supporting the catalyst component in a desired dispersed state and has sufficient electronic conductivity as a current collector. The main component is carbon. Preferably there is. Specifically, carbon particles such as carbon black such as ketjen black, channel black, furnace black and thermal black, activated carbon, coke and the like can be mentioned. Further, since the carbon particles are excellent in corrosion resistance and water repellency, graphitized particles are preferably used.

  In the present invention, “the main component is carbon” refers to containing a carbon atom as a main component, and is a concept including both a carbon atom only and a substantially carbon atom. In some cases, elements other than carbon atoms may be included in order to improve the characteristics of the fuel cell. In addition, being substantially composed of carbon atoms means that mixing of impurities of about 2 to 3% by mass or less is allowed.

The specific surface area of the conductive carrier is preferably 20 to 1600 m ² / g, more preferably 80 to 1200 m ² / g. If the specific surface area is less than 20 m ² / g, the dispersibility of the catalyst component and the electrolyte on the conductive support may be reduced, and sufficient power generation performance may not be obtained. If the specific surface area exceeds 1600 m ² / g, the catalyst The effective utilization rate of components and electrolytes may decrease.

  Further, the size of the conductive carrier is not particularly limited, but from the viewpoint of controlling the ease of loading, the catalyst utilization, and the thickness of the electrode catalyst layer within an appropriate range, the average particle size is 5 to 200 nm. The thickness is preferably about 10 to 100 nm.

  In the electrode catalyst in which the catalyst component is supported on the conductive support, the supported amount of the catalyst component is preferably 10 to 80% by mass, more preferably 30 to 70% by mass with respect to the total amount of the electrode catalyst. Good. If the loading amount exceeds 80% by mass, the degree of dispersion of the catalyst component on the conductive support is lowered, and although the loading amount is increased, the improvement in power generation performance is small and the economic advantage may be lowered. On the other hand, if the loading amount is less than 10% by mass, the catalytic activity per unit mass is lowered, and a large amount of electrode catalyst is required to obtain the desired power generation performance, which is not preferable. The amount of the catalyst component supported can be examined by inductively coupled plasma emission spectroscopy (ICP).

  In each catalyst layer used for the anode and the cathode, the mixing mass ratio of the electrolyte material and the electrode catalyst is preferably 1: 0.01 to 1:10, more preferably 1: 0.1 to 1: 5. Thereby, a membrane electrode assembly having sufficient power generation performance can be obtained.

  More preferably, the electrode catalyst layer is formed by fixing the electrode catalyst and the electrolyte material with the polymer. As a result, an electrode having a desired shape such as a film, a cast product, and the like that can exist independently can be obtained, and the pores in the electrode catalyst layer are blocked by a liquid room temperature molten salt. Accordingly, it is possible to prevent a decrease in the diffusibility of the reaction gas in the electrode catalyst layer, thereby improving the reliability and power generation performance of the membrane electrode assembly.

  The electrode catalyst layer in which the electrolyte material and the electrode catalyst are fixed by a polymer is as described in the method for producing a membrane electrode assembly of the present invention described later, and can constitute the electrode catalyst, the electrolyte material, and the polymer. It is obtained by polymerizing a solution containing a monomer and a polymerization initiator.

  As the polymer, since the same polymer as described above that can be filled together with the electrolyte material in the pores of the porous support in the electrolyte membrane is used, detailed description thereof is omitted here.

  The polymer content in the electrode catalyst layer is preferably 5 to 80% by mass, more preferably 10 to 40% by mass, based on all components. If the content of the polymer is less than 5% by mass, the effect of adding the polymer may not be sufficiently obtained. If the content exceeds 80% by mass, the content of the electrode catalyst and the electrolyte decreases, and the membrane electrode There is a possibility that the power generation performance of the joined body is lowered.

  The thickness of each catalyst layer in the anode and the cathode is preferably 5 to 100 μm, more preferably 10 to 50 μm. If the thickness of the catalyst layer exceeds 5 μm, the diffusibility of the reaction gas may decrease and power generation performance may decrease, and if it is less than 100 μm, sufficient power generation performance may not be obtained.

<Gas diffusion layer>
Next, each electrode in the anode and the cathode may have a gas diffusion layer in addition to the above-described electrode catalyst layer. The gas diffusion layer is disposed on a surface opposite to the surface of the electrode catalyst layer that contacts the electrolyte membrane.

  In the electrode having the electrode catalyst layer and the gas diffusion layer, the electrode catalyst layer may be formed on the gas diffusion layer, or the electrode catalyst layer may be formed in a part of the gas diffusion layer. In the case of the latter, the thing which the electrode catalyst and the electrolyte material were impregnated in the site | part which the gas diffusion base material mentioned later mentions is mentioned.

  The gas diffusion layer is not particularly limited, and known ones can be used in the same manner, for example, a sheet-like gas diffusion group having conductivity and porosity such as carbon woven fabric, paper-like paper body, felt, and non-woven fabric. The thing which consists of materials is mentioned.

  The thickness of the gas diffusion base material may be appropriately determined in consideration of the characteristics of the obtained gas diffusion layer, but may be about 30 to 500 μm. If the thickness is less than 30 μm, sufficient mechanical strength or the like may not be obtained, and if it exceeds 500 μm, the distance through which gas or water permeates is undesirably increased.

  The gas diffusion base material preferably contains a water repellent for the purpose of further improving water repellency and preventing flooding. Although it does not specifically limit as said water repellent, Fluorine-type, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyhexafluoropropylene, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), etc. Examples thereof include polymer materials, polypropylene, and polyethylene.

  In order to further improve water repellency, the gas diffusion layer may have a carbon particle layer made of an aggregate of carbon particles containing a water repellent on the gas diffusion base material.

  The carbon particles are not particularly limited, and may be conventional ones such as carbon black, graphite, and expanded graphite. Of these, carbon blacks such as oil furnace black, channel black, lamp black, thermal black, and acetylene black are preferred because of their excellent electron conductivity and large specific surface area.

  Examples of the water repellent used for the carbon particle layer include the same water repellents as those described above used for the gas diffusion base material. Of these, fluorine-based polymer materials are preferably used because of their excellent water repellency and corrosion resistance during electrode reaction.

  The mixing ratio between the carbon particles and the water repellent in the carbon particle layer may be insufficient to obtain water repellency as expected when there are too many carbon particles. If there are too many water repellents, sufficient electron conductivity may be obtained. There is a risk that it will not be obtained. Considering these, the mixing ratio of the carbon particles and the water repellent in the carbon layer is preferably about 90:10 to 40:60 in terms of mass ratio.

  The thickness of the carbon particle layer may be appropriately determined in consideration of the water repellency of the obtained gas diffusion layer, but is preferably 10 to 1000 μm, more preferably 50 to 500 μm.

  The second of the present invention is a fuel cell using the above-mentioned first membrane electrode assembly of the present invention. In the present invention, since an electrolyte membrane having a room temperature molten salt impregnated in a porous support is used, the power generation performance can be greatly improved as a fuel cell to which the room temperature molten salt is applied, and safety and reliability are high. In addition, it is possible to provide a fuel cell capable of reducing costs by reducing the amount of catalyst used.

The type of fuel of the fuel cell is not particularly limited, and in the above description, hydrogen has been described as an example, but in addition to this, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol Secondary butanol, tertiary butanol, dimethyl ether, diethyl ether, ethylene glycol, diethylene glycol can be used.
Of these, hydrogen and methanol are preferred because they can increase the output.

  The fuel cell is useful as a power source for a moving body such as an automobile having a limited mounting space in addition to a stationary power source. Especially, since it is excellent in electric power generation performance and reliability, it is especially preferable to be used as a power source for mobile bodies such as automobiles.

  The configuration of the fuel cell is not particularly limited, and a conventionally known technique may be appropriately used. Generally, the fuel cell has a structure in which a membrane electrode assembly is sandwiched between separators. A fuel cell having such a structure is shown in FIG.

  FIG. 1 is a schematic cross-sectional view of a fuel cell of the present invention. The fuel cell 100 in FIG. 1 includes a fuel electrode having a pair of electrodes, that is, a fuel electrode catalyst layer 120a and a fuel electrode gas diffusion layer 130a on both sides of the electrolyte membrane 110, and an oxygen electrode catalyst layer 120c and oxygen electrode gas diffusion. A membrane electrode assembly 140 in which an oxygen electrode having a layer 130 c is disposed is further sandwiched between two separators 150. Further, the separator 150 has a gas flow path 151 for supplying a reaction gas supplied from the outside such as a fuel gas containing hydrogen or an oxidant gas containing oxygen to the fuel electrode catalyst layer 120a or the oxygen electrode catalyst layer 120c. .

  The separator can be used without limitation as long as it is conventionally known, such as those made of carbon such as dense carbon graphite and a carbon plate, and those made of metal such as stainless steel. The separator has a function of separating air and fuel gas, and a channel groove for securing the channel may be formed. The thickness and size of the separator, the shape of the flow channel, and the like are not particularly limited, and may be appropriately determined in consideration of the output characteristics of the obtained fuel cell.

  Furthermore, a stack in which a plurality of membrane electrode assemblies are stacked via a separator and connected in series may be formed so that the fuel cell can obtain a desired voltage or the like. The shape of the fuel cell is not particularly limited, and may be determined as appropriate so that desired battery characteristics such as voltage can be obtained.

  A third aspect of the present invention is a fuel cell system using the second fuel cell of the present invention.

  In a fuel cell using conventional Nafion (registered trademark) as an electrolyte, especially when a stack is formed by stacking membrane electrode assemblies, the power generation efficiency decreases due to the high current density, and the heat dissipation increases. It is necessary to cool the fuel cell to 80 ° C. or lower. Therefore, it is necessary to increase the radiator area as compared with the conventional internal combustion engine vehicle. However, as in the present invention, a fuel cell using room temperature molten salt as an electrolyte can be operated at a high temperature of 120 ° C. or higher. Therefore, it is possible to reduce the size of the radiator to the same extent as that of a conventional internal combustion engine vehicle. Furthermore, since it is not necessary to humidify the fuel gas or oxidant gas supplied into the fuel cell, the fuel cell system of the present invention does not require a humidifier. Therefore, according to the present invention, it is possible to provide a fuel cell system that is simplified, reduced in cost, and reduced in capacity.

The configuration of the fuel cell system can be the same as that of a conventional general fuel cell system except that the second fuel cell of the present invention is used. For example, JP 2005-50639 A, The fuel cell systems described in JP-A-2005-71748, JP-A-2004-234862, JP-A-2002-246054, and the like are preferably used. At this time, as described above, the humidifier can be omitted.

  4th of this invention is a manufacturing method of the 1st membrane electrode assembly of this invention.

The first production method of the membrane electrode assembly is a method in which a porous support is impregnated with a monomer solution (A) containing a polymerization initiator, a monomer, and an electrolyte material composed of a cation and an anion. And obtaining an electrolyte membrane,
A step in which a monomer solution (B) containing a polymerization initiator, a monomer, and an electrode catalyst is applied on a support and then polymerized to obtain an electrode;
Joining the electrolyte membrane and the electrode.

  The polymerization initiator needs to be appropriately selected according to a polymerization method such as a thermal polymerization method, an ultraviolet polymerization method, a radiation polymerization method, and an electron beam polymerization method and a monomer to be polymerized. For example, persulfates such as ammonium persulfate group, sodium persulfate and potassium persulfate; hydrogen peroxide; 2,2′-azobis (2-amidinopropane) dihydrochloride, azobis-2-methylpropionamidine hydrochloride, azo Azo compounds such as isobutyronitrile; peroxides such as benzoyl peroxide and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide and the like. These polymerization initiators can be used alone or in the form of a mixture of two or more. At this time, as a promoter, reducing agents such as sodium bisulfite, sodium sulfite, molle salt, sodium pyrobisulfite, formaldehyde sodium sulfoxylate, ascorbic acid; amine compounds such as ethylenediamine, sodium ethylenediaminetetraacetate, glycine; Species or two or more can be used in combination.

  The content of the polymerization initiator in the monomer solution (A) is not particularly limited, but is 0.05 to 2.0% by mass, preferably 0.2 to 0.8% by mass with respect to the monomer solution (A). It is good to do.

  Further, the monomer, the electrolyte material, and the porous support are as described in the first aspect of the present invention, and thus detailed description thereof is omitted here.

  The content of the monomer in the monomer solution (A) is not particularly limited, but is 10% by weight or more, preferably 30 to 60% by weight, based on the total polymer components.

  Although content in particular of the said electrolyte material in the said monomer solution (A) is not restrict | limited, It is 10-90 mass% with respect to a monomer solution (A), Preferably it is good to set it as 40-70 mass%.

  Solvents used for the monomer solution (A) include water; lower alcohols such as methyl alcohol, ethyl alcohol and 2-propanol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane and n-hexane; acetic acid Ester compounds such as ethyl; ketone compounds such as acetone and methyl ethyl ketone; and the like. These may be used individually by 1 type, and 2 or more types may be mixed and used for them.

  The viscosity of the monomer solution (A) is 5 to 100 cP, preferably 10 to 40 cP at 25 to 50 ° C. from the viewpoint of easily forming a film or impregnating a porous support as described later. It is good to do.

  In order to impregnate the porous support with the monomer solution (A), a method of applying and impregnating the monomer solution (A) to the porous support, a method of immersing the porous support in the monomer solution (A) Etc. are used.

  The monomer solution (A) may be applied to the porous support by a known method, for example, curtain coating method, extrusion coating method, roll coating method, spin coating method, dip coating method, bar coating method, spraying method. A coating method, a slide coating method, a printing coating method, or the like can be used.

  Next, the polymerization method of the monomer solution (A) impregnated in the porous support is appropriately determined depending on the type of the polymerization initiator used, and the monomer is polymerized (crosslinked) with heat, ultraviolet rays, radiation, electron beam, or the like. You can do it.

  In the method of the present invention, the monomer solution (A) is preferably polymerized by thermal polymerization in order to fix the room temperature molten salt as an electrolyte membrane. For the thermal polymerization, a conventionally known apparatus such as a vacuum dryer can be used. The conditions for thermal polymerization are determined according to the monomer solution (A), and the monomer solution (A) is preferably heated to 60 to 150 ° C., particularly 80 to 100 ° C. If the heating temperature of the monomer solution (A) is less than 60 ° C., the polymerization may not proceed, and if it exceeds 150 ° C., the polymerization may occur rapidly and a good quality electrolyte membrane may not be obtained. The polymerization time may be about 30 to 1800 minutes, particularly about 300 to 900 minutes.

  Next, in the method of the present invention, a monomer solution (B) containing a polymerization initiator, a monomer, an electrode catalyst, and an electrolyte material composed of a cation and an anion is applied onto a support and then polymerized to form an electrode. The process of obtaining is performed.

  The polymerization initiator, the monomer, the electrolyte material, and the solvent used in the monomer solution (B) are the same as those described in the monomer solution (A). The electrode catalyst is as described in the first aspect of the present invention.

  The content of the polymerization initiator in the monomer solution (B) is not particularly limited, but is 0.05 to 2% by mass, preferably 0.2 to 0.8% by mass with respect to the monomer solution (B). It is good to do.

  The content of the monomer in the monomer solution (B) is not particularly limited, but is 10% by weight or more, preferably 30 to 60% by weight with respect to the total polymer components.

  Although content in particular of the said electrolyte material in the said monomer solution (B) is not restrict | limited, It is 10-90 mass% with respect to a monomer solution (B), Preferably it is good to set it as 40-70 mass%.

  The content of the electrode catalyst in the monomer solution (B) is not particularly limited, but is 5 to 50% by mass, preferably 10 to 40% by mass with respect to the monomer solution (B).

  The viscosity of the monomer solution (B) is 5 to 100 cP, preferably 10 to 40 cP at 25 to 50 ° C. from the viewpoint of easy application.

  While the monomer solution (B) has fluidity, it is preferably formed into a film by using a known method such as coating on a flat support or putting it in a petri dish or the like.

  The flat substrate on which the monomer solution (B) is applied is not particularly limited as long as it can be formed into a film, and examples thereof include a glass substrate, a metal substrate, a polymer film, and a reflector. Examples of the polymer film include cellulose polymer films such as TAC (triacetyl cellulose), ester polymer films such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), PTFE (polytrifluoroethylene), and the like. And fluorinated polymer films, polyimide films and the like.

  About the coating method of a monomer solution (B) to a flat support body, the thing similar to what was described in the monomer solution (A) is used.

  Moreover, as a support body which apply | coats the said monomer solution (B), the said sheet | seat-like gas diffusion base material which comprises a gas diffusion layer, the said gas diffusion base material in which the carbon particle layer was formed, etc. can also be used.

  Moreover, the polymerization method of the monomer solution (B) is appropriately determined depending on the kind of the polymerization initiator used, and the monomer may be polymerized (crosslinked) with heat, ultraviolet rays, radiation, electron beam or the like.

  In the method of the present invention, the monomer solution (B) is preferably polymerized by thermal polymerization in order to fix the room temperature molten salt as an electrolyte membrane. For the thermal polymerization, a conventionally known apparatus such as a vacuum dryer can be used. The conditions for the thermal polymerization are determined according to the monomer solution (B), and the monomer solution (B) is preferably heated to 60 to 150 ° C, particularly 80 to 100 ° C. When the heating temperature of the monomer solution (B) is less than 60 ° C., the polymerization may not proceed, and when it exceeds 150 ° C., the polymerization proceeds rapidly and a good quality electrolyte membrane may not be obtained. The polymerization time may be about 30 to 1800 minutes, particularly about 300 to 900 minutes.

  In the method of the present invention, the step of joining the electrolyte membrane produced as described above and the electrode is not particularly limited. However, after the electrode catalyst layers are disposed on both sides of the electrolyte membrane, hot press is performed. A method or the like is preferably used.

  The hot pressing is not particularly limited, but is preferably performed at 110 to 170 ° C. and a pressing pressure of 1 to 5 MPa for 3 to 10 minutes.

  When the support used for preparing the electrode catalyst layer is other than the gas diffusion base material constituting the gas diffusion layer, after performing the hot pressing, the support such as the flat plate support is peeled off. Further, a gas diffusion layer may be disposed outside the electrode catalyst layer.

  As a method for producing the membrane / electrode assembly of the present invention, the following method may be used in addition to the method described above.

The second production method of the membrane electrode assembly includes a step of impregnating a porous support with a monomer solution (A) containing a polymerization initiator, a monomer, and an electrolyte material composed of a cation and an anion;
Applying a monomer solution (B) containing a polymerization initiator, a monomer, an electrode catalyst, and an electrolyte material composed of a cation and an anion onto a support to obtain an electrode precursor;
A step of polymerizing the monomer (A) and the monomer solution (B) after disposing the electrode precursor on both sides of the porous support impregnated with the monomer solution (A). It is a manufacturing method.

  In the method, the monomer solution (A), the porous support, and the method of impregnating the monomer solution (A) into the porous support may be performed in the same manner as in the first method of the present invention.

  In the step of obtaining the electrode catalyst layer precursor, the monomer solution (B) and the method of applying the monomer solution (B) on the support may be performed in the same manner as the first method of the present invention described above. Therefore, detailed description is omitted.

  In the second method of the present invention, after the electrode catalyst layer precursor is disposed on both sides of the porous support impregnated with the monomer solution (A), the monomer solution (A) and the monomer solution (B) are arranged. Is polymerized. According to such a method, the monomer polymerization step and the step of joining the electrode and the electrolyte membrane can be performed at a time, and the manufacturing process can be simplified.

  The polymerization is appropriately determined depending on the type of polymerization initiator used, and the monomers contained in the monomer solution (A) and the monomer solution (B) can be polymerized (crosslinked) by heat, ultraviolet rays, radiation, electron beams, or the like. That's fine.

  In the method of the present invention, in order to fix the room temperature molten salt as an electrolyte membrane, the monomer is preferably polymerized by thermal polymerization. For the thermal polymerization, a conventionally known apparatus such as a vacuum dryer can be used. The thermal polymerization conditions are determined according to the monomer, and the electrode catalyst layer precursor and the laminate of the electrolyte membrane are preferably heated to 60 to 150 ° C., particularly 80 to 150 ° C. If the heating temperature is less than 60 ° C., the polymerization may not proceed, and if it exceeds 150 ° C., the polymerization proceeds rapidly, and a good quality electrolyte membrane may not be obtained. The polymerization time may be about 30 to 1800 minutes, particularly about 300 to 900 minutes.

  At this time, while heating, the said laminated body may be pressurized with the pressure of about 1-5 Mpa.

  After the polymerization is completed, the support used for preparing the electrode catalyst layer precursor is peeled off to obtain a membrane electrode assembly. Further, when the support used for preparing the electrode catalyst layer precursor is other than the gas diffusion base material constituting the gas diffusion layer, the plate-like support is peeled off after the polymerization is completed. Further, it is preferable to dispose a gas diffusion layer outside the electrode catalyst layer.

  Moreover, as a manufacturing method of the membrane electrode assembly of this invention, the following method may be sufficient.

The third production method of the membrane electrode assembly includes impregnating a porous support with a monomer solution (A) containing a polymerization initiator, a monomer, and an electrolyte material composed of a cation and an anion;
Impregnating the monomer solution (A) into a gas diffusion substrate on which an electrode catalyst is supported to obtain an electrode precursor;
And a step of polymerizing the monomer (A) after disposing the electrode precursor on both sides of the porous support impregnated with the monomer solution (A).

  In the method, the step of impregnating the porous support with the monomer solution (A) containing the polymerization initiator, the monomer, and the electrolyte material composed of the cation and the anion is the first method of the present invention described above. Therefore, detailed description is omitted.

  In the third method of the present invention, the electrode precursor is obtained by impregnating the monomer solution (A) in a predetermined portion of the gas diffusion substrate on which the electrode catalyst is supported. Thereby, an electrode having an electrode catalyst layer formed on a part of the gas diffusion layer is obtained. The electrode catalyst and the gas diffusion base material are as described in the first aspect of the present invention.

  In the gas diffusion base material on which the electrode catalyst is supported, the portion where the electrode catalyst is supported may be appropriately determined in consideration of the power generation performance of the obtained electrode. For example, the electrode catalyst may be supported in a range of preferably about 5 to 100 μm, more preferably about 10 to 50 μm from the surface of the gas diffusion substrate that can come into contact with the electrolyte membrane.

  Commercially available products such as LT 140E-W and HT 140E-W manufactured by E-TEK may be used as the gas diffusion base material on which the electrode catalyst is supported. In addition, the electrode catalyst is supported by a known method such as an impregnation method, a liquid phase reduction loading method, an evaporation to dryness method, a colloid adsorption method, a spray pyrolysis method, or a reverse micelle (microemulsion method). Alternatively, the gas diffusion base material may be produced by itself.

In the gas diffusion substrate on which the electrode catalyst is supported, the amount of the electrode catalyst supported is not particularly limited, but the mass of the catalyst component per 1 cm ² of the gas diffusion substrate is preferably 0.1 to 10 mg, More preferably, it may be 0.2 to 5 mg.

The “unit area of the gas diffusion base material” means the area of the surface that can contact the electrolyte membrane of the gas diffusion base material. Therefore, in the present invention, the “mass of catalyst component per unit area” is a value obtained by dividing the amount of catalyst component (mg) contained in the catalyst layer by the area (cm ² ) of the gas diffusion substrate on the electrolyte membrane. To do.

  Next, an electrode precursor is obtained by impregnating the monomer solution (A) into a gas diffusion substrate on which the electrode catalyst is supported. As said monomer solution (A), the thing similar to what was described in the 1st method mentioned above is used.

  In the electrode precursor, the part impregnated with the monomer solution (A) is not particularly limited, but the monomer solution (A) is at least part of the gas diffusion substrate on which the electrode catalyst is supported. ) May be impregnated. In addition, as a method for impregnating the monomer solution (A) into the gas diffusion substrate on which the electrode catalyst is supported, the monomer solution (A) is applied to and impregnated into the gas diffusion substrate using a known coating method. In addition to the method used, a method of immersing a predetermined portion of the gas diffusion base material in the monomer solution (A) is used.

  After obtaining the porous support and electrode precursor impregnated with the monomer solution (A) as described above, the electrode precursor is disposed on both sides of the porous support impregnated with the monomer solution (A). After obtaining a laminate, the monomer solution (A) contained in the laminate is polymerized. According to such a method, the monomer polymerization step and the step of joining the electrode and the electrolyte membrane can be performed at a time, and the manufacturing process can be simplified.

  The polymerization is appropriately determined depending on the type of the polymerization initiator used, and the monomer contained in the monomer solution (A) may be polymerized (crosslinked) with heat, ultraviolet rays, radiation, electron beam or the like.

  In the method of the present invention, in order to fix the room temperature molten salt as an electrolyte membrane, the monomer is preferably polymerized by thermal polymerization. For the thermal polymerization, a conventionally known apparatus such as a vacuum dryer can be used. The conditions for thermal polymerization are determined according to the monomer, and the electrode precursor and the laminate of the electrolyte membrane are preferably heated to 60 to 150 ° C., particularly 80 to 150 ° C. If the heating temperature is less than 60 ° C., the polymerization may not proceed, and if it exceeds 150 ° C., the polymerization proceeds rapidly, and a good quality electrolyte membrane may not be obtained. The polymerization time may be about 30 to 1800 minutes, particularly about 300 to 900 minutes.

  At this time, while heating, the said laminated body may be pressurized with the pressure of about 0.01-5 Mpa.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Example 1
After mixing 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF ₄ ) and 2-hydroxylethyl methacrylate (HEMA) at a mass ratio of 5: 5 as a room temperature molten salt, benzoyl is used as a polymerization initiator. Peroxide was mixed at 0.5% by mass with respect to the mixed solution. The obtained mixed liquid (A) was impregnated by applying it to a PTFE porous support (thickness 30 μm, porosity 63%, size 30 mm × 30 mm).

Next, a gas diffusion base material (LT140E-W manufactured by E-TEK, thickness 400 μm, Pt support amount 5 g / m ² ) in which platinum is supported as an electrode catalyst on a base material made of carbon cloth is mixed with the mixed solution (A ) Was applied up to a depth of about 20 μm to obtain an electrode precursor.

  The electrode precursor was placed on both sides of the PTFE porous support impregnated with the mixed solution (A) with the surface coated with the mixed solution (A) on the inside, and the resulting laminate was A membrane electrode assembly was produced by polymerization and bonding by heating at 80 ° C. for 24 hours while applying pressure at 0.05 MPa.

(Comparative Example 1)
1. Production of Membrane Electrode Assembly Platinum-supported carbon (TEC10E50E, Tanaka Kikinzoku Kogyo Co., Ltd., TEC10E50E, platinum content 46.5 wt%) 10 g, solid polymer electrolyte solution (DuPont Nafion solution DE520, electrolyte content 5 wt%) 90 g, pure water 25 g Then, 10 g of 2-propanol (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) was mixed and dispersed for 3 hours using a homogenizer in a glass container in a water bath set to be kept at 20 ° C. to prepare a catalyst ink. did.

  Using carbon paper (TGP-H-060 manufactured by Toray Industries, Inc., thickness 200 μm), this is punched into a 100 mm × 100 mm square, used as a base material constituting a gas diffusion layer, and the catalyst ink is applied to the base material And dried in an oven at 100 ° C. for 30 minutes. As a result, an electrode catalyst layer having a thickness of 40 μm was obtained on the substrate.

  Next, the electrode catalyst layer forming side of the two electrode catalyst layer forming substrates prepared above faces each other with a polymer electrolyte membrane (Nafion NR-112 manufactured by DuPont) having a square of 100 mm on a side and a thickness of 30 μm. Thus, the membrane electrode assembly was obtained by hot pressing at 130 ° C. for 10 minutes at a pressure of 3 MPa per base material.

(Reference Example 1)
A power generation test was performed on an electrolyte in a solution state containing only EMIBF ₄ . As shown in FIG. 2, a gas diffusion substrate (E--) in which a spacer having a square hole of 5 cm ² is placed in the center, and both sides of the spacer are coated with a PTFE gasket and platinum similar to that used in Example 1. TE140, LT140E-W, thickness 400 μm, Pt carrying amount 5 g / m ² ), and EMIBF ₄ was injected into the square hole of the spacer to form a membrane electrode assembly.

(Evaluation)
The power generation performance of the membrane electrode assembly produced above was evaluated according to the following procedure.

  Each membrane / electrode assembly was sandwiched between graphite separators, and further sandwiched between gold-plated stainless steel current collector plates to form single cells for evaluation.

  In the evaluation unit cell, hydrogen was supplied as a fuel to the anode side, and oxygen was supplied as an oxidant to the cathode side. For both gases, the cell outlet pressure was atmospheric pressure and no humidification, hydrogen was set to 25 ° C., air was set to 25 ° C., cell temperature was set to 25 ° C., the hydrogen flow rate was 200 ml / min, and the oxygen flow rate was 200 ml / min. A power generation test was conducted under these conditions. The results are shown in FIG.

  From the results shown in FIG. 3, it can be seen that according to the membrane electrode assembly of the present invention, high IV characteristics can be obtained even in a non-humidified state.

The cross-sectional schematic diagram of the fuel cell using the membrane electrode assembly of this invention is shown. The perspective view of the fuel cell in a reference example is shown. It is a graph which shows the evaluation result of the membrane electrode assembly in an Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Fuel cell, 110 ... Electrolyte membrane, 120a ... Fuel electrode catalyst layer, 120c ... Oxygen electrode catalyst layer, 130a ... Fuel electrode side gas diffusion layer, 130c ... Oxygen electrode side gas diffusion layer, 140 ... Membrane electrode assembly, 150 ... Separator, 151 ... Gas supply path.

Claims (16)

A membrane electrode assembly in which electrodes are arranged on both sides of an electrolyte membrane,
A membrane electrode assembly, wherein the electrolyte membrane includes an electrolyte material composed of a cation and an anion, and a porous support.   The membrane electrode assembly according to claim 1, wherein the electrolyte material is a room temperature molten salt. The membrane electrode assembly according to claim 1 or 2, wherein the room temperature molten salt does not contain an anion represented by the following chemical formula (I).

(X is any of group 17 elements, y represents a positive real number, 1.0 ≦ y ≦ 2.3)   The membrane electrode assembly according to any one of claims 1 to 3, wherein the porosity of the porous support is 5 to 95%.   The membrane electrode assembly according to claim 1, wherein the porous support has a thickness of 10 μm to 200 μm.   The membrane electrode joint according to any one of claims 1 to 5, wherein the porous support is made of at least one selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide, and polyimide. body.   The membrane electrode assembly according to any one of claims 1 to 5, wherein the porous support is an inorganic porous body. The membrane electrode assembly according to claim 7, wherein the inorganic porous body is made of at least one selected from the group consisting of Al ₂ O ₃ , SiO ₂ , TiO ₂ , and ZrO ₂ .   The membrane electrode assembly according to claim 1, wherein the electrolyte membrane further contains a polymer.   The polymer is at least one polymer selected from the group consisting of polyethylene oxide, polypropylene oxide, polyacrylonitrile, polymethyl methacrylate, and polyvinylidene fluoride, and / or acrylic acid monomer, methacrylic acid monomer, acrylamide type The membrane electrode assembly according to claim 9, which is a polymer of at least one monomer selected from the group consisting of a monomer, an allyl monomer, a styrene monomer, and an epoxy monomer.   The membrane electrode assembly according to claim 9, wherein the polymer is a polymer of a monomer component having 2-hydroxylethyl methacrylate as a main component.   A fuel cell using the membrane electrode assembly according to claim 1.   A fuel cell system using the fuel cell according to claim 12. It is a manufacturing method of the membrane electrode assembly according to any one of claims 1 to 11,
A step of impregnating a porous support with a monomer solution (A) containing a polymerization initiator, a monomer, and an electrolyte material composed of a cation and an anion, followed by polymerization to obtain an electrolyte membrane;
Applying a monomer solution (B) containing a polymerization initiator, a monomer, an electrode catalyst, and an electrolyte material composed of a cation and an anion onto a support and then polymerizing the solution to obtain an electrode catalyst layer;
The manufacturing method of the membrane electrode assembly which has the process of joining the said electrolyte membrane and the said electrode catalyst layer. It is a manufacturing method of the membrane electrode assembly according to any one of claims 1 to 11,
Impregnating a porous support with a monomer solution (A) containing a polymerization initiator, a monomer, and an electrolyte material composed of a cation and an anion;
Applying a monomer solution (B) containing a polymerization initiator, a monomer, an electrode catalyst, and an electrolyte material composed of a cation and an anion onto a support to obtain an electrode catalyst layer precursor;
A step of polymerizing the monomer (A) and the monomer solution (B) after disposing the electrode catalyst layer precursor on both sides of the porous support impregnated with the monomer solution (A). Manufacturing method of joined body. It is a manufacturing method of the membrane electrode assembly according to any one of claims 1 to 11,
Impregnating a porous support with a monomer solution (A) containing a polymerization initiator, a monomer, and an electrolyte material composed of a cation and an anion;
Impregnating the monomer solution (A) into a gas diffusion substrate on which an electrode catalyst is supported to obtain an electrode precursor;
And a step of polymerizing the monomer (A) after disposing the electrode precursor on both sides of the porous support impregnated with the monomer solution (A).

Images