JP2012204274A - Electrolyte membrane and catalyst layer-electrolyte membrane laminate, membrane electrode assembly and fuel cell using the same, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrolyte membrane which can maintain excellent power generation performance stably for a long period in a hot and non-humidified state, and a catalyst layer-electrolyte membrane laminate, a membrane electrode assembly and a fuel cell using the electrolyte membrane, and a manufacturing method thereof.SOLUTION: An electrolyte membrane 10 of the present invention is an electrolyte membrane containing a solid polymer compound having an imidazole group, in which a first layer 1 contains a solid acid and a binder and a second layer 2 contains a solid polymer compound having an imidazole group and a liquid electrolyte, the first layer 1 being disposed on both principal surfaces of the second layer 2. The electrolyte membrane 10 is obtained by forming resin film using a second layer formation resin composition containing a solid polymer compound having an imidazole group, and then forming a second layer 2 by impregnating the resultant resin film with a liquid electrolyte, and, thereafter, forming a first layer on both principal surfaces of the second layer which was obtained by using a first layer formation electrolyte composition containing a solid acid and a binder.

Description

  The present invention relates to an electrolyte membrane, a catalyst layer-electrolyte membrane laminate using the same, a membrane electrode assembly and a fuel cell, and a method for producing the same.

In recent years, with increasing environmental awareness, fuel cells have attracted attention as clean energy that does not emit CO ₂ or pollutants. Among them, the development of a polymer electrolyte fuel cell (PEFC) using a solid polymer electrolyte that has high energy efficiency and a temperature range of around 100 ° C. and is easy to handle for general use is expected.

A polymer electrolyte fuel cell is basically composed of a membrane electrode assembly in which electrodes are bonded to both surfaces of an electrolyte membrane usually made of a solid polymer electrolyte. As the solid polymer electrolyte, perfluorosulfonic acid or the like that is generally known as Nafion (registered trademark) manufactured by DuPont is used, but protons are conducted in a state where the proton conduction mechanism is H ₃ O ^+. Therefore, there is a problem that proton conductivity is remarkably lowered at a temperature of 80 ° C. or higher, and a system is complicated because it is necessary to provide a humidifying mechanism.

  Therefore, PBI (polybenzimidazole) membrane impregnated with phosphoric acid has been proposed as an electrolyte membrane that can be used under non-humidified conditions (see, for example, Patent Documents 1 to 5). However, polybenzimidazole itself does not have ionic conductivity, so it is necessary to increase the amount of phosphoric acid to be impregnated. Thus, there is a problem that the ionic conductivity of the electrolyte membrane decreases with time.

Special table 2001-510931 gazette Japanese National Patent Publication No. 11-503262 JP 2003-327826 A JP 2008-218299 A JP 2007-115426 A

  In order to solve the above-described conventional problems, the present invention provides an electrolyte membrane that can stably maintain good power generation performance for a long period of time in a high temperature and non-humidified state, and a catalyst layer-electrolyte membrane laminate and membrane electrode joint using the electrolyte membrane Body, fuel cell, and manufacturing method thereof.

  The electrolyte membrane of the present invention is an electrolyte membrane including a solid polymer compound having an imidazole group, wherein the first layer includes a solid acid and a binder, and the second layer includes a solid polymer having an imidazole group. It includes a molecular compound and a liquid electrolyte, and the first layer is disposed on both main surfaces of the second layer.

  The catalyst layer-electrolyte membrane laminate of the present invention comprises the electrolyte membrane of the present invention and a pair of catalyst layers, wherein the catalyst layers are respectively disposed on both main surfaces of the electrolyte membrane. To do.

  The membrane electrode assembly of the present invention comprises the electrolyte membrane of the present invention, a pair of catalyst layers, and a pair of gas diffusion layers, and the catalyst layer and the gas diffusion layer on both main surfaces of the electrolyte membrane. Are stacked in this order.

  The fuel cell of the present invention includes the electrolyte membrane of the present invention, a pair of catalyst layers, a pair of gas diffusion layers, and a pair of separators, and the catalyst layer and the gas on both main surfaces of the electrolyte membrane. The diffusion layer and the separator are laminated in this order.

  The method for producing an electrolyte membrane of the present invention is a method for producing an electrolyte membrane containing a solid polymer compound having an imidazole group, and uses the second layer-forming resin composition containing a solid polymer compound having an imidazole group. And forming a second layer by impregnating the obtained resin film with a liquid electrolyte, and using the first layer-forming electrolyte composition containing a solid acid and a binder. A step of forming the first layer on each of the main surfaces of the second layer.

  The present invention provides a liquid from an electrolyte membrane by disposing a first layer containing a solid acid and a binder on both main surfaces of a solid polymer compound having an imidazole group and a second layer containing a liquid electrolyte. Provided are an electrolyte membrane capable of preventing electrolyte from flowing out and stably maintaining good power generation performance for a long period of time in a high temperature and non-humidified state, and a catalyst layer-electrolyte membrane laminate, a membrane electrode assembly and a fuel cell using the electrolyte membrane . Further, according to the production method of the present invention, the electrolyte membrane of the present invention can be easily obtained.

FIG. 1 is a schematic cross-sectional view showing an example of an electrolyte membrane according to Embodiment 1 of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of a catalyst layer-electrolyte membrane laminate according to Embodiment 2 of the present invention. FIG. 3 is a schematic cross-sectional view showing an example of a membrane electrode assembly according to Embodiment 3 of the present invention. FIG. 4 is a schematic cross-sectional view showing an example of a fuel cell according to Embodiment 4 of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. Note that the embodiments described below exemplify materials and manufacturing methods for embodying the technical idea of the present invention, and the technical idea of the present invention is limited to the following materials and manufacturing methods. Not what you want. The technical idea of the present invention can be variously modified within the scope of the claims.

[Embodiment 1]
First, an electrolyte membrane will be described as Embodiment 1 of the present invention.

(Electrolyte membrane)
FIG. 1 is a schematic cross-sectional view showing an example of an electrolyte membrane according to Embodiment 1 of the present invention. As shown in FIG. 1, the electrolyte membrane 10 includes a first layer 1 (1a, 1b) and a second layer 2, and the first layer 1a, 1b is arranged. The first layer 1 includes a solid acid and a binder, and the second layer 2 includes a solid polymer compound having an imidazole group and a liquid electrolyte. Further, from the viewpoint of enhancing ion conductivity, the second layer 2 may further contain a solid acid. The types of solid acids contained in the first layer 1 and the second layer 2 may be the same or different. Further, from the viewpoint of good moldability and excellent mechanical strength, the second layer 2 may further contain a binder.

  The thickness of the electrolyte membrane 10 is not particularly limited, but is usually 20 to 1000 μm, and preferably 20 to 300 μm from the viewpoint of mechanical strength. Moreover, although the thickness of the 1st layer 1 is not limited, Usually, it is 5-1000 micrometers, and it is preferable that it is about 10-300 micrometers from a viewpoint of mechanical strength. The thickness of the second layer 2 is not limited, but is usually 5 to 1000 μm, and preferably 10 to 300 μm from the viewpoint of mechanical strength.

<Solid polymer compound having imidazole group>
In the present invention, the solid polymer compound having an imidazole group forms the basic structure of the second layer.

  The solid polymer compound having an imidazole group is not particularly limited, but it is preferable to use one or more polymer compounds selected from the group consisting of polybenzimidazole, polyimidazole, and polyvinylimidazole from the viewpoint of excellent heat resistance. More preferably, polybenzimidazole is used.

  Polybenzimidazole is not particularly limited, but can be produced by a known technique. For example, U.S. Pat. No. 3,313,783, U.S. Pat. No. 3,509,108, U.S. Pat. No. 3,555,389 and U.S. Pat. It is preferable to manufacture based on the manufacturing method described in the above.

<Liquid electrolyte>
The liquid electrolyte provides ionic conductivity to the second layer. The liquid electrolyte is not particularly limited as long as it has ion conductivity.

  As the liquid electrolyte, for example, a strong acid, an ionic liquid, or the like can be used.

  As the strong acid, for example, liquid phosphoric acid, sulfuric acid, nitric acid, hydrofluoric acid, hydrochloric acid, hydrobromic acid and the like are preferably used. In the present invention, liquid phosphoric acid refers to liquid phosphoric acid such as phosphoric acid aqueous solution and phosphoric acid solution. In the present invention, phosphoric acid includes orthophosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, metaphosphoric acid, paraphosphoric acid, and the like.

  In the present invention, the ionic liquid is also referred to as a room temperature molten salt, and means a liquid that is in a liquid state at room temperature (20 ± 15 ° C.) among melts composed only of ions. The ionic liquid is composed of a cation component and an anion component.

  The cation component of the ionic liquid is not particularly limited, and examples thereof include imidazolium derivatives, pyridinium derivatives, pyrrolidinium derivatives, ammonium derivatives, those having a nitrogen-containing heterocyclic ring, guanidinium derivatives, and isouronium derivatives. Among these, from the viewpoint of heat resistance, conductivity, etc., it is preferably at least one selected from the group consisting of imidazolium derivatives and ammonium derivatives, such as 1-methyl-3-methylimidazolium cation, 1-ethyl-3-methyl. More preferably, it is at least one selected from the group consisting of an imidazolium cation and a diethylmethylammonium cation.

The anion component of the ionic liquid is not particularly limited. For example, sulfates, sulfonic acids, amides, imides, methanes, halogens, boron-containing anions, phosphates, antimony, hydrofluoride anion, fluorine System anions, thiocyanates and the like. Among these, from the viewpoint of heat resistance, conductivity, etc., it is preferably at least one selected from the group consisting of sulfates, imides and thiocyanates, [CF ₃ SO ₃ ] ⁻ , [(FSO ₂ ) ₂ N] ^- and [SCN] ^- it is more preferably one or more selected from the group consisting of. From the viewpoint of excellent ion conductivity, the anion components are [CF ₃ SO ₃ ] ⁻ , [(FSO ₂ ) ₂ N] ⁻ , [SCN] ⁻ , [HSO ₄ ] ⁻ and bis (trifluoromethanesulfonyl) amide (bis). (Trifluoromethanesulfonyl) amide, also referred to as HTFSI in the following) is preferably at least one selected from the group consisting of [CF ₃ SO ₃ ] ⁻ , [HSO ₄ ] ⁻ and HTFSI. More preferably.

  In the present invention, the ionic liquid preferably contains protic ions. In the present invention, “protic ion” means an ion having proton accepting property and / or proton donating property.

The protic ion is not particularly limited, and examples thereof include proton monohydrogen sulfate ion (HSO ₄ ⁻ ), monohydrogen phosphate ion (HPO ₄ ²⁻ ), dihydrogen phosphate ion (H ₂ PO ₄ ⁻ ), and selenium. Acid monohydrogen ion (HSeO ₄ ⁻ ), pyrohydrogen monohydrogen ion (HP ₂ O ₇ ³⁻ ), dihydrogen pyrophosphate ion (H ₂ P ₂ O ₇ ²⁻ ), trihydrogen pyrophosphate ion (H ₃ P ₂₎ O ₇ ⁻ ), phosphonate monohydrogen ion (H ₂ PO ₃ ⁻ ) and the like.

  The ionic liquid may contain one or more of the above-described cation components. Further, the ionic liquid may contain one or more of the above-mentioned anion components.

  The ionic liquid can be obtained by a known method (for example, see J. AM. CHEM. SOC. 2010, 132, pages 964-9773, etc.). In the present invention, an ionic liquid produced by a known method may be used, or a commercially available product may be used. Examples of commercially available products include 1-ethyl-3-methylimidazolium bis (fluorosulfonyl) imide (1-Ethyl-3-methylimidazolium bis (fluorosulfonyl) imide) manufactured by Mitsubishi Materials Corporation, and 1- 1 manufactured by Merck & Co., Inc. 1-Ethyl-3-methylimidazolium triflate, 1-ethyl-3-methylimidazolium hydrogen sulfate, 1-ethyl-3-methyl imidazole, 1-ethyl-3-methylimidazolium triflate (1-Ethyl-3-methylimidazolium triflate), 1-Ethyl-3-methylimidazolium hydrogen sulfate (1-Ethyl-3-methylimidazolium hydrogensulfate) Lithium thiocyanate (1-Ethyl-3-methylimidazolium thiocynate) or the like can be used. . Alternatively, an ionic liquid obtained by mixing a commercially available cation component and an anion component, for example, imidazolium bis obtained by mixing imidazole manufactured by Tokyo Chemical Industry Co., Ltd. and HTFSI manufactured by Wako Pure Chemical Industries, Ltd. (Trifluoromethanesulfonyl) amide, 2-ethylimidazole manufactured by Tokyo Chemical Industry Co., Ltd., and imidazolium bis (trifluoromethanesulfonyl) amide obtained by mixing HTFSI manufactured by Wako Pure Chemical Industries, Ltd. It may be used.

  As the liquid electrolyte, it is preferable to use one or more selected from the group consisting of liquid phosphoric acid, sulfuric acid and ionic liquid from the viewpoint of excellent ionic conductivity, more preferably liquid phosphoric acid, and aqueous phosphoric acid solution. More preferably, it is used. Moreover, it is preferable to use polybenzimidazole as the solid polymer compound having an imidazole group and use an aqueous phosphoric acid solution as the liquid electrolyte because it has excellent ion conductivity at a high temperature of 100 to 300 ° C. and in a non-humidified state.

<Solid acid>
In the present invention, the “solid acid” means a solid that exhibits acid characteristics. The solid acid is not particularly limited. For example, an inorganic solid acid or an organic solid acid can be used. From the viewpoint of proton conductivity, proton conductivity can be obtained in a temperature range from room temperature to 200 ° C. and in a non-humidified atmosphere. It is preferable to use a solid acid. In the present invention, the non-humidified atmosphere means that intentional humidification is not performed in an atmosphere in which an object (solid acid) is placed. In addition, room temperature means that, for the purpose of the present invention, intentional temperature adjustment is not performed in an atmosphere in which an object (solid acid) is placed.

  The organic solid acid is not particularly limited as long as it is an organic acid. From the viewpoint of ion conductivity, it is preferable to use an organic solid acid having a sulfonic acid group, a naphthalene compound, or the like. Examples of the compound having a sulfonic acid group include benzenesulfonic acid, dodecylbenzenesulfonic acid, 2-naphthalenesulfonic acid, 1,5-naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid, 1,3,6-naphthalenetri Sulfonic acid, 1,3,5,7-naphthalene tetrasulfonic acid and the like can be used. Examples of the naphthalene-based compound include naphthalene, 2-methylnaphthalene, 1-naphthol, 2-naphthol, naphthoic acid, naphthonitrile, naphthylamine, and acenaphthene. The organic acid solid acids may be used singly or in combination of one or more.

  As the inorganic solid acid, for example, an inorganic solid acid having proton conductivity can be used, and an inorganic salt having proton conductivity is preferable.

  Examples of the inorganic salt having proton conductivity include metal phosphates and metal sulfates.

  Examples of the metal phosphate include compounds such as orthophosphate and pyrophosphate. Specific examples of the metal phosphate include orthophosphates and pyrophosphates such as tin, zirconium, cesium, and tungsten.

  As the pyrophosphate, a metal phosphate represented by the following general formula (1) is preferably used from the viewpoint of excellent proton conductivity.

[Chemical 1]
M _1-x D _x P ₂ O ₇ (1)

  However, in the general formula (1), x is 0 ≦ x <0.5, and M (main metal) is Zr, Cs, Sn, Ti, Si, Ge, Pb, Hf, Ca, Mg, W, Na And D (doped metal) is a kind selected from the group consisting of Al, In, B, Ga, Sc, Yb, Ce, La, Sb, Y, Nb and Mg. .

  The metal phosphate represented by the general formula (1) includes Zr, Cs, Sn, Ti, Si, Ge, Pb, Hf, Ca, Mg, W, Na, or Al as the main metal, Pyrophosphates doped with different metals are preferred. When a doped metal is used, it is preferable to use Sn, Cs, Ti, or Zr as the main metal from the viewpoint of stability as a phosphate. More preferably, it is a pyrophosphate in which a part of a metal such as tin or cesium is substituted with a doped metal element such as indium, aluminum or antimony.

  As the doped metal, for example, when Sn is used as the main metal, In, Al, and the like are preferable because they can be dissolved in the main metal. The mixing ratio of the main metal and the dope metal varies depending on the solid solubility limit. However, when Sn is used as the main metal and In is used as the dope metal, for example, the molar ratio is Sn: In = 7: 3-9.8: 0.2 A range of is desirable.

  The metal phosphate represented by the general formula (1) can be synthesized, for example, by heating one or more metal oxides and phosphoric acid and performing heat treatment.

  The metal oxide is not particularly limited as long as it can generate phosphoric acid and a crystalline salt. Examples thereof include oxides of Zr, Cs, Sn, Ti, Si, Ge, Pb, Hf, Ca, Mg, W, Na, and Al. As the phosphoric acid, either liquid phosphoric acid or solid phosphoric acid may be used. From the viewpoint of avoiding the problem of loss of phosphoric acid during heat treatment, it is preferable to use solid phosphoric acid. As solid phosphoric acid, for example, ammonium monohydrogen phosphate, ammonium dihydrogen phosphate and the like can be used.

  Specifically, the metal phosphate represented by the general formula (1) can be produced as follows. First, a compound containing a main metal such as tin (hereinafter simply referred to as a main metal compound) and a compound containing a doped metal such as indium (hereinafter also simply referred to as a doped metal compound) and liquid phosphoric acid are mixed. A mixture is obtained. Next, water is added to the obtained mixture, and the mixture is stirred and dispersed with a stirrer or the like at a temperature of 100 to 300 ° C. for 1 to 3 hours to obtain a dispersion. The obtained dispersion is put in a crucible and baked at a temperature of 300 to 700 ° C. for 1 to 3 hours, for example. Since phosphoric acid may be lost in the high temperature state, it is desirable to add the liquid phosphoric acid in excess, for example, 1.1 to 1.5 times the molar equivalent. In addition, as a main metal compound and dope metal compound, a metal oxide, a metal hydroxide, a metal chloride, a metal nitrate etc. can be used, for example.

  In the above, in order to avoid the problem of disappearance of phosphoric acid during firing, solid phosphoric acid may be used instead of liquid phosphoric acid. As the solid phosphoric acid, for example, using ammonium monohydrogen phosphate, ammonium dihydrogen phosphate, etc., a metal oxide containing a main metal such as tin and a metal oxide containing a doped metal such as indium and a predetermined number of moles. Mix with. The metal oxide containing the main metal and the metal oxide containing the doped metal are preferably mixed at a molar ratio of the main metal to the doped metal of, for example, 9: 1 to 1: 1. The obtained mixture is put into a crucible and baked at a temperature of 300 to 650 ° C. for 1 to 3 hours, for example. The resulting product can then be ground in an agate bowl to give the desired metal phosphate. By using solid phosphoric acid, a molar equivalent of phosphoric acid reacts with the metal oxide, and the excess is volatilized at a high temperature, so that excess phosphoric acid does not adhere and a reproducible metal phosphate can be obtained. it can.

Moreover, the said metal phosphate can also be produced by a coprecipitation method. For example, tin chloride pentahydrate (SnCl ₄ .5H ₂ O) and indium chloride tetrahydrate (InCl ₃ .4H ₂ O) are added at a predetermined concentration so that a molar ratio of tin to indium is about 9: 1. After adjusting to an aqueous solution, while stirring with a stirrer, an aqueous ammonia solution is added dropwise until the pH becomes 7, whereby a small amount of indium hydroxide (In (OH) ₃ ) is uniformly contained in tin hydroxide (Sn (OH) ₄ ). A precipitate in the state present in is obtained. Thereafter, the precipitate is sucked and filtered to dry, the dried precipitate and phosphoric acid are mixed, and heat treatment is performed at about 200 ° C. for about 2 hours in a reducing atmosphere to obtain a metal phosphate. . Finally, wash with deionized water. According to the coprecipitation method, a metal phosphate in which a doped metal is uniformly doped into a main metal phosphate is prepared by simultaneously precipitating a plurality of types of hardly soluble salts from a solution containing a plurality of desired metal ions. be able to.

  The solid acid may be an electrolyte composed of a metal phosphate represented by the general formula (1) and phosphoric acid.

  In the electrolyte composed of the metal phosphate represented by the general formula (1) and phosphoric acid, the number of atoms of the metal element of the metal phosphate and the metal element to be doped is [m] and [n], respectively. When the sum of the number of phosphorus atoms in the metal phosphate and the number of phosphorus atoms in phosphoric acid is [p], it is preferable to satisfy the following formula (1).

[Equation 1]
2 <[p] / ([m] + [n]) ≦ 4 (1)

  More preferably, the following mathematical formula (2) is satisfied.

[Equation 2]
2.4 ≦ [p] / ([m] + [n]) ≦ 3.2 (2)

  By satisfy | filling the said Numerical formula (1), while high proton conductivity is obtained, a moldability will become favorable. When the value of the mathematical formula [p] / ([m] + [n]) is 2 or less, the amount of phosphoric acid on the metal phosphate is decreased, and proton conductivity may not be improved. On the other hand, when the value of the above formula [p] / ([m] + [n]) exceeds 4, the amount of phosphoric acid is too large, moisture absorption in the atmosphere is high, and the molded body becomes brittle, so that the shape is maintained. There is a fear that it cannot be done.

Further, as the inorganic salt having proton conductivity, a complex of a heteropolyacid and an inorganic salt may be used. Examples of the inorganic salt include hydrogen sulfate and hydrogen phosphate. Examples of the hydrogen sulfate include cesium hydrogen sulfate and potassium hydrogen sulfate. Examples of the hydrogen phosphate include cesium hydrogen phosphate. Further, cesium carbonate (Cs ₂ CO ₃ ), cesium sulfate (Cs ₂ SO ₄ ), or the like may be used instead of hydrogen sulfate or hydrogen phosphate. Examples of the heteropolyacid include tungsten phosphoric acid (H ₃ PW ₁₂ O ₄₀ : WPA). From the viewpoint of proton conductivity, the complex of heteropolyacid and inorganic salt is preferably a complex of hydrogensulfate and heteropolyacid, more preferably a complex of potassium hydrogensulfate and tungsten phosphate obtained by a mechanochemical method. Is the body.

A complex of tungsten phosphoric acid and potassium hydrogen sulfate (KHSO ₄ ), which is a kind of a complex of a heteropolyacid and an inorganic salt, can be produced by, for example, the following mechanochemical method. WPA (H ₃ PW ₁₂ O ₄₀ : 12 Tungsto (VI) phosphoric acid n hydrate) is preliminarily dried at a temperature of 60 ° C. for 5 to 24 hours to form hexahydrate (WPA · 6H ₂ O). Next, the obtained WPA · 6H ₂ O, potassium hydrogen sulfate (KHSO ₄ ) and the ball are put in an agate pot. Then, the complex of tungsten phosphoric acid and potassium hydrogen sulfate (KHSO ₄ ) is obtained by mixing at 720 rpm for 10 minutes with a planetary ball mill (manufactured by Frichce Japan KK, P-7). It is preferable that the compounding quantity of tungsten phosphoric acid and potassium hydrogensulfate is 1: 99-40: 60 by molar ratio, for example.

  In the mechanochemical method, a composite of tungsten phosphate and potassium hydrogen sulfate is synthesized by utilizing a large mechanical energy such as impact and friction obtained by milling using a ball mill or the like. Therefore, when a complex of tungsten phosphoric acid and potassium hydrogen sulfate is produced by the above mechanochemical method, it is relatively easy to produce because a high-temperature process is not required as in the production of metal phosphate. There is an advantage.

It is thought that the above-mentioned milling treatment is related to the improvement of conductivity by the formation of hydrogen bonds in the form of Bronsted acid-base pairs between the KPA Keggin anion PW ₁₂ O ₄₀ ³⁻ and the HSO ₄ ⁻ anion of KHSO _4. It is done. Combining hydrogen sulfate and heteropoly acid by mechanochemical method, introducing defect structures and random structures at high density on the surface of inorganic solids, and designing a hydrogen bond network is a composite with high proton conductivity in a wide temperature range It is an important guide for synthesizing the body.

  Moreover, as said solid acid, it is preferable to use the metal phosphate or metal sulfate represented by following General formula (2) from a viewpoint that it is excellent in proton conductivity.

[Chemical formula 2]
L _a H _b (XO _t ) _c (2)

  However, in General formula (2), L is 1 type chosen from the group which consists of K, Rb, and Cs, X is 1 type chosen from the group which consists of P and S, and a, b, c, and t are rational numbers. It is.

  Among the metal phosphates represented by the general formula (2), it is more preferable to use a metal phosphate or a metal sulfate represented by the following general formula (3).

[Chemical formula 3]
Cs _a H _b (XO _t ) _c (3)

Examples of the metal phosphate or metal sulfate represented by the general formula (3) include cesium phosphate (cesium phosphate) and cesium sulfate. Examples of the cesium phosphate include cesium dihydrogen phosphate (CsH ₂ PO ₄ ), cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ), and the like.

Further, as the solid acid, a complex of cesium phosphoric acid and silicon phosphate (SiP ₂ O ₇ ) may be used. Examples of the cesium phosphoric acid include cesium dihydrogen phosphate (CsH ₂ PO ₄ ), cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ), and the like. In addition, cesium phosphate, silicon phosphate, and those composites are, for example, “Toshiaki Matsui, Tomokazu Kukino, Ryuji Kikuchi, and Koichi Eguchi, The 3 A3, A3. "Toshiaki Matsui, Tomokazu Kukino, Ryuji Kikuchi, and koichi Eguchi, Electrochemical Acta 51 (2006) 3719-3723" and the like.

Complex of cesium dihydrogen phosphate (CsH ₂ PO ₄ ) and silicon phosphate (SiP ₂ O ₇ ) or cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ) For example, the composite is prepared as follows.

First, cesium dihydrogen phosphate (CsH ₂ PO ₄ ) or cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) is prepared as follows. Cesium carbonate (Cs ₂ CO ₃ ) and water are mixed and stirred with a stir bar using a stirrer or the like. Subsequently, liquid phosphoric acid is dripped little by little, and water is evaporated, stirring at the temperature of 100-150 degreeC for 1-3 hours. Then, it puts into oven and is dried at the temperature of 100-150 degreeC, for example. The drying time is, for example, 1 day to several days. Next, the obtained product is pulverized in an agate bowl into a powder form to obtain the desired cesium dihydrogen phosphate (CsH ₂ PO ₄ ) or cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ). Can do.

Next, silicon phosphate (SiP ₂ O ₇ ) is produced as follows. A mixture of silicon dioxide (SiO ₂ ) and liquid phosphoric acid is placed in an agate noodle and mixed until it becomes a starchy candy. Then, it puts into an alumina crucible and fires at a temperature of 100 to 700 ° C. The firing time is, for example, 30 to 80 hours. Then, the obtained product can be pulverized in an agate bowl to obtain the desired silicon phosphate (SiP ₂ O ₇ ).

Next, cesium dihydrogen phosphate (CsH ₂ PO ₄ ) or cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ) are blended in a predetermined number of moles. The obtained mixture is dispersed by a pod mill, a ball mill or the like, and a composite of cesium dihydrogen phosphate (CsH ₂ PO ₄ ) and silicon phosphate (SiP ₂ O ₇ ) or cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) A composite of ₂ ) and silicon phosphate (SiP ₂ O ₇ ) is obtained. The dispersion time is, for example, 1 to 30 hours. The blending amount of cesium dihydrogen phosphate or cesium dihydrogen phosphate and silicon phosphate is preferably 1: 4 to 2: 1 in molar ratio.

As the solid acid, potassium phosphate, silicon phosphate (SiP ₂ O ₇ ), or a complex of potassium phosphate and silicon phosphate (SiP ₂ O ₇ ) may be used. Examples of the potassium phosphoric acid include potassium dihydrogen phosphate (KH ₂ PO ₄ ) and potassium pentahydrogen diphosphate (KH ₅ (PO ₄ ) ₂ ). Complex of potassium dihydrogen phosphate (KH ₂ PO ₄ ) and silicon phosphate (SiP ₂ O ₇ ) or complex of potassium dihydrogen phosphate (KH ₅ (PO ₄ ) and silicon phosphate (SiP ₂ O ₇ ) The bodies are cesium dihydrogen phosphate (CsH ₂ PO ₄ ) and silicon phosphate (SiP ₂ O ₇ ), respectively, except that potassium carbonate (K ₂ CO ₃ ) is used instead of cesium carbonate (Cs ₂ CO ₃ ). ) Or a complex of cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ).

  Since the organic solid acid dissolves in the solvent, the compatibility with the binder component is good, and the dispersibility becomes good at the time of preparing the electrolyte composition, so that the effect of improving the quality of the electrolyte membrane is easily obtained. On the other hand, since an inorganic solid acid is excellent in heat resistance and durability, it is easy to obtain an effect that the mechanical strength after forming an electrolyte into a film becomes good.

  Although the said solid acid is not specifically limited, A particle size is 0.1-200 micrometers in an electrolyte membrane, Preferably it is 0.1-150 micrometers. The solid acid as a raw material before forming the electrolyte membrane also has a particle size of 0.1 to 200 μm, preferably 0.1 to 150 μm. When the particle size of the solid acid is 0.1 to 200 μm, the dispersibility at the time of preparing the electrolyte composition is improved, and an electrolyte membrane having a good film quality is easily obtained. In the present invention, the particle size of the solid acid can be measured using a scanning electron microscope (SEM) or the like.

<Binder>
The binder is not particularly limited as long as it has binding properties. For example, a fluorine polymer, a hydrocarbon polymer, a fluorine ionomer, a hydrocarbon ionomer, an epoxy resin, an acrylic resin, or the like is used. Can do. Especially, what has the acid resistance in the range of pH 1-3 and the heat resistance in the temperature range of 50-300 degreeC is preferable. Moreover, you may have ion conductivity.

  The fluorine-based polymer is not particularly limited. For example, tetrafluoroethylene (PTFE), polyvinylidene fluoride, fluorinated ethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene perfluoroalkyl vinyl ether copolymer. A fluororesin such as (PFA) can be used.

  The hydrocarbon polymer is a polymer having a hydrocarbon compound as a main skeleton, such as polyimide, polyamideimide, polystyrene sulfide, polybenzimidazole, polypyridine, polypyrimidine, polyimidazole, polybenzothiazole, poly Benzooxazole, polyoxadiazol, polyxylone, polyquinoxaline, polythiadiazol, polytetrazavilen, polyoxazole, polythiazole, polyvinyl pyridine, polyvinyl imidazole, and the like can be used.

  The fluorine ionomer is not particularly limited. For example, perfluorosulfonic acid such as Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., and Aciplex (registered trademark) manufactured by Asahi Kasei. For example, a sulfonyl fluoride vinyl ether (SFVE) -tetrafluoroethylene copolymer such as Aquivion (registered trademark) manufactured by Asahi Kasei Corporation can be used.

  The hydrocarbon ionomer is not particularly limited. For example, polyarylene ether sulfonic acid, polystyrene sulfonic acid, syndiotactic polystyrene sulfonic acid, polyphenylene ether sulfonic acid, modified polyphenylene ether sulfonic acid, polyether sulfone sulfonic acid, polyether. Ether ketone sulfonic acid (sulfonated polyether ether ketone) and polyphenylene sulfide sulfonic acid can be used.

  As the epoxy resin, bisphenol A type epoxy resin, novolac type phenol resin, or the like can be used. Also, a hybrid resin of the above resin and silica can be used.

  As the acrylic resin, polymethyl methacrylate, polystyrene, or the like can be used. Also, a hybrid resin of the above resin and silica can be used.

  The binder may be a cellulosic polymer. Examples of the cellulose polymer include methyl cellulose, carboxymethyl cellulose, and cellulose acetate.

  Among the binders mentioned above, PTFE, polyvinylidene fluoride, perfluorosulfonic acid, cellulose acetate, sulfonyl fluoride vinyl ether (SFVE) -tetrafluoroethylene copolymer, polyether ether ketone sulfone from the viewpoint of durability and binding properties. Acid, polybenzimidazole, polyimidazole, polypyridine, and polypyrimidine are preferably used. The polyether ether ketone sulfonic acid is not particularly limited. L. Those synthesized based on the method described in Di Vona et al, Polymer 46 (2005) pp. 1754-1758 can be used.

  Only one type of binder described above may be used, or two or more types may be used in appropriate combination.

  Hereinafter, a method for manufacturing the electrolyte membrane will be described.

(Method for manufacturing electrolyte membrane)
The electrolyte membrane 10 of the present invention is not particularly limited. For example, after the second layer 2 is formed, the first layer 1 (1a, 1b) is formed on both main surfaces of the second layer 2, respectively. Can be produced.

<Formation of second layer>
First, a second layer-forming resin composition containing a solid polymer compound having an imidazole group is applied onto a substrate and dried to form a resin film. In addition, what was mentioned above should just be used as a solid polymer compound which has an imidazole group.

  As the second layer-forming resin composition, a resin composition obtained by mixing and dispersing a mixture containing a solid polymer compound having an imidazole group and a solvent with a disperser can be used. As the disperser, an ultrasonic disperser, a homogenizer, a ball mill, or the like can be used.

  The solvent is not particularly limited as long as it can disperse a solid polymer compound having an imidazole group. For example, ethanol, methanol, 1-butanol, t-butanol, propanol, N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, dimethylformamide, methanesulfonic acid and the like can be used.

  The second layer forming resin composition may further contain a solid acid and / or a binder. From the viewpoint of achieving both ion conductivity and moldability or mechanical strength, the blending amount of the solid polymer having a solid acid and an imidazole group in the second layer-forming resin composition is 10: 1. It is preferably ˜1: 10, more preferably 2: 1 to 1: 5, and still more preferably 1: 1 to 1: 5. From the viewpoint of achieving both ion conductivity and moldability or mechanical strength, the blending amount of the solid polymer compound having a binder and an imidazole group in the second layer-forming resin composition is 1: It is preferably 1 to 1:10, and more preferably 1: 1 to 1: 5. In the present invention, the mass of the binder refers to the mass of the solid content of the binder.

  As the substrate, for example, a polymer film or the like can be used. Examples of the polymer film include polyimide, polyethylene terephthalate, polyparvanic acid aramid, polyamide (nylon), polysulfone, polyethersulfone, polyphenylene sulfide, polyetheretherketone, polyetherimide, polyarylate, polyethylene naphthalate (PET). A polymer film composed of, for example, can be used. Further, heat resistance of ethylene tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroperfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), etc. A polymer film made of a conductive fluororesin may be used. Among these, a polymer film that is inexpensive and easily available is preferable, and a PET film is more preferable.

  The method for applying the second layer-forming resin composition to the substrate is not particularly limited. For example, knife coater, bar coater, spray coating, dip coater, spin coater, roll coater, die coater, curtain coater. Application methods such as screen printing and rolling can be used.

  Moreover, in the above, drying temperature is 50-300 degreeC, for example, Preferably it is 100-250 degreeC. If the drying temperature is lower than 50 ° C, the solvent contained in the resin composition may not be removed. On the other hand, when the drying temperature exceeds 300 ° C., the binder may be thermally decomposed. The drying time is, for example, 10 minutes to 5 hours, preferably 10 minutes to 3 hours. Examples of the drying method include natural drying, far-red drying, hot air drying, reduced pressure drying, and heating.

  Next, the obtained resin film is impregnated with a liquid electrolyte to form the second layer 2. What is necessary is just to use the above-mentioned as a liquid electrolyte. The substrate may be peeled off by 180 degree peeling before or after impregnating the resin film with the liquid electrolyte. However, it is preferable to peel the resin film before impregnating the resin film with the liquid electrolyte.

  The impregnation is not particularly limited, but can be performed, for example, by immersing a resin film in a liquid electrolyte. The temperature of the liquid electrolyte at the time of immersion is, for example, room temperature to 200 ° C., and is preferably room temperature to 100 ° C. from the viewpoint of safety and ease of handling. Further, the immersion time is appropriately adjusted according to the target impregnation rate when the resin film is impregnated with the liquid electrolyte. In addition, after immersing a resin film in a liquid electrolyte as needed, you may dry for 1 to 60 minutes at the temperature of room temperature-100 degreeC. Examples of the drying method include natural drying, far-red drying, hot air drying, reduced pressure drying, and heating. From the viewpoint of safety and operability, it is preferable to use a phosphoric acid aqueous solution as the liquid electrolyte, and it is more preferable to use a 75 to 122 mass% phosphoric acid aqueous solution.

  The impregnation rate (doping amount) of the liquid electrolyte into the resin film is preferably 150 to 400% by mass, and more preferably 150 to 300% by mass with respect to the mass of the resin film.

The impregnation rate (doping amount) of the liquid electrolyte is expressed by the following formula (W ₁₎ where W ₁ is the mass of the resin film before impregnating the liquid electrolyte, and W ₂ is the mass of the resin film after impregnating the liquid electrolyte. 3).

[Equation 3]
Impregnation rate (%) = (W ₂ −W ₁ ) / W ₁ × 100 (3)

  Further, when the resin film is a polybenzimidazole film and the liquid electrolyte is a phosphoric acid aqueous solution, the impregnation ratio of the phosphoric acid aqueous solution to the polybenzimidazole film is 150 to 400 mass from the viewpoint of excellent ion conductivity. %, And more preferably 150 to 300% by mass.

<Formation of the first layer>
The first layer-forming electrolyte composition containing a solid acid and a binder is applied on both main surfaces of the second layer 2 and dried to form the first layers 1a and 1b, respectively. Alternatively, first, a first layer-forming electrolyte composition containing a solid acid and a binder is applied onto a substrate and dried to form first layers 1a and 1b, respectively. Next, the first layers 1a and 1b formed on the substrate are both main layers of the second layer 2 so that the main surfaces of the first layers 1a and 1b and the main surface of the second layer 2 are in contact with each other. Arrange each on the surface to obtain a laminate. Thereafter, a hot pressing process such as hot pressing is performed from both sides of the obtained laminate, and then the base material is peeled off from the first layers 1a and 1b. 1 layers 1a and 1b are formed. In addition, what is necessary is just to use the above-mentioned thing as a solid acid, a binder, and a base material.

  As the first layer-forming electrolyte composition, an electrolyte composition obtained by mixing and dispersing a mixture containing a solid acid and a binder with a disperser can be used. As the disperser, an ultrasonic disperser, a homogenizer, a ball mill, or the like can be used.

  The first layer forming electrolyte composition may further contain a solvent. The solvent is not particularly limited as long as it does not aggregate the binder. For example, water, ethanol, methanol, 1-butanol, t-butanol, propanol, N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, dimethylformamide, methanesulfonic acid and the like can be used. When the first layer-forming electrolyte composition contains a solvent, the solid acid may be added to the binder solution or dispersion, and then the solvent may be added to produce the first layer-forming electrolyte composition.

  In the first layer-forming electrolyte composition, from the viewpoint of enhancing battery performance, the blending amount of the solid acid and the binder is preferably 10: 0.5 to 10:10 in terms of mass ratio. It is more preferably 0.5 to 10: 5, and further preferably 10: 0.5 to 10: 3.

  When an electrolyte composed of metal phosphate and phosphoric acid is used as the solid acid, the metal phosphate is powdered, mixed and dispersed by adding phosphoric acid and a binder, and the first layer forming electrolyte composition Can be made. Alternatively, after adding a predetermined amount of phosphoric acid to the metal phosphate, a binder is added to the product fired at 100 to 200 ° C. for 30 minutes to 2 hours to prepare the first layer-forming electrolyte composition. Good. In the above, the compounding quantity of metal phosphate and phosphoric acid is 5: 0.2-5: 2, preferably 5: 0.3-5: 1.2, more preferably 5: 0. Adjust to 8-5: 1, most preferably 5: 0.9. In the above case, the water contained in the phosphoric acid is volatilized by the baking treatment, and the orthophosphoric acid on the metal phosphate is condensed to produce a phosphoric acid condensate such as pyrophosphoric acid or metaphosphoric acid. By cross-linking the acid condensate and the metal phosphate, a network with phosphoric acid is formed around the metal phosphate, and the charged phosphoric acid accumulates at high density, and good proton conductivity is expressed. At the same time, the strength of the electrolyte is estimated to increase.

  Application | coating of the electrolyte composition for 1st layer formation on the main surface of 2nd layer 2 or a base material is not specifically limited, For example, the time of application | coating to the base material of 2nd layer formation resin composition It can carry out with the application | coating method similar to the apply | coating method of this. The drying can be performed under the same conditions as the drying at the time of forming the resin film.

  In the above, the heat press process with respect to the laminated body at the time of 1st layer formation is not specifically limited, It can carry out by various press processes. Moreover, the pressure at the time of hot pressing is not particularly limited, but is usually 0.5 to 10 MPa, preferably 1 to 10 MPa, for example. Moreover, the temperature at the time of hot pressing is not particularly limited, but is usually 30 to 200 ° C., preferably 50 to 250 ° C., for example. Moreover, what is necessary is just to determine suitably the press time at the time of hot-pressing according to temperature, for example, normally 10 to 240 second, Preferably it is 30 to 180 second.

  Moreover, peeling of the base material from the 1st layer formed on the base material is not specifically limited, It can carry out by 180 degree peeling.

  According to this embodiment, an electrolyte membrane is provided by disposing a first layer containing a solid acid and a binder on both main surfaces of a solid polymer compound having an imidazole group and a second layer containing a liquid electrolyte. Thus, it is possible to provide an electrolyte membrane that can prevent liquid electrolyte from flowing out and can stably maintain good power generation performance for a long period of time in a high temperature and non-humidified state.

[Embodiment 2]
Hereinafter, a catalyst layer-electrolyte membrane laminate will be described as Embodiment 2 of the present invention.

(Catalyst layer-electrolyte membrane laminate)
FIG. 2 is a schematic cross-sectional view showing an example of a catalyst layer-electrolyte membrane laminate according to Embodiment 2 of the present invention. As shown in FIG. 2, the catalyst layer-electrolyte membrane laminate 20 includes an electrolyte membrane 10 and a pair of catalyst layers 6 and 7, and the catalyst layers 6 and 7 are respectively formed on both main surfaces of the electrolyte membrane 10. Is arranged. In FIG. 2, the same parts as those in FIG. 2 and 1 have the same function.

  The catalyst is not particularly limited as long as it is a substance that promotes the anode and / or cathode reaction in the fuel cell. For example, platinum-supported carbon, platinum-ruthenium-supported carbon, platinum-cobalt-supported carbon, gold-supported carbon, silver-supported carbon, iron-cobalt-nickel-supported carbon, etc .; platinum black, platinum-ruthenium black, platinum-cobalt Examples thereof include metal fine particles such as black, gold black and silver black; inorganic substances such as molybdenum carbide. Of these, platinum-supporting carbon with high catalytic activity, molybdenum carbide with low phosphoric acid poisoning, and the like are suitable.

  The catalyst layers 6 and 7 may contain the solid acid shown in Embodiment 1 from the viewpoint of increasing the reaction field. The solid acid preferably contains the same solid acid as the electrolyte membrane from the viewpoint of adhesion.

  Moreover, the catalyst layers 6 and 7 may contain the liquid electrolyte shown in Embodiment 1 from a viewpoint of increasing a reaction field. The liquid electrolyte can be included in the catalyst layer by preparing the catalyst layer using a catalyst paste containing the liquid electrolyte. Or you may make a catalyst layer contain a liquid electrolyte by apply | coating and impregnating a liquid electrolyte to the catalyst layer which does not contain a liquid electrolyte. As the liquid electrolyte, it is preferable to use an aqueous phosphoric acid solution having a concentration of about 75 to 122% by mass from the viewpoints of ion conductivity, handleability, and the like. The liquid electrolyte is preferably contained in such an amount that does not block the pores of the catalyst layer.

  Moreover, the catalyst layers 6 and 7 may contain a binder. The catalyst layers 6 and 7 can be formed by using only a catalyst, but a catalyst layer having excellent mechanical strength can be obtained by coating and molding a paste obtained by adding a binder. . As the binder, for example, the binder shown in Embodiment 1 can be used.

  The thicknesses of the catalyst layers 6 and 7 may be appropriately determined in consideration of the type of electrode base material, the thickness of the electrolyte membrane, and the like. The thickness of the catalyst layers 6 and 7 is, for example, 20 to 3000 μm, and preferably 30 to 2000 μm.

  The catalyst layer-electrolyte membrane laminate 20 can be manufactured, for example, by applying a catalyst paste containing a catalyst on both main surfaces of the electrolyte membrane 10 and drying to form the catalyst layers 6, 7. Alternatively, in the catalyst layer-electrolyte membrane laminate 20, for example, a catalyst paste containing a catalyst is applied on a substrate and dried to form a catalyst layer, and then the catalyst layer formed on the substrate is converted to the catalyst layer 6. , 7 and the main surface of the electrolyte membrane 10 are arranged on both main surfaces of the electrolyte membrane 10 to obtain a laminate, and hot press treatment such as hot pressing is performed from both sides of the obtained laminate. And then the substrate can be peeled off.

  The catalyst paste is obtained, for example, by mixing and dispersing a mixture containing a catalyst and a solvent with a disperser. As the disperser, an ultrasonic disperser, a homogenizer, a ball mill, or the like can be used. The catalyst paste may contain a solid acid, a binder, a liquid electrolyte, and the like.

  The solvent is not particularly limited as long as it can disperse the catalyst. For example, water, ethanol, methanol, 1-butanol, t-butanol, propanol, N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, dimethylformamide and the like can be used.

  When the catalyst paste contains a solid acid, the concentration of the solid content composed of the catalyst and the solid acid is preferably 50% by mass or less, more preferably 40% by mass with respect to the catalyst paste, from the viewpoint of coatability. It is as follows. Moreover, it is preferable that the compounding quantity of a catalyst and a solid acid is 10: 1-0.1: 1 by mass ratio, More preferably, it is 5: 1-0.25: 1.

  When the said catalyst paste contains a binder, it is preferable that the addition amount of the said binder (solid content) is 50 mass% or less with respect to solid content in a catalyst paste, and it is more preferable that it is 40 mass% or less. In this case, after adding the catalyst and the solid acid to the binder solution or dispersion, a solvent may be added to produce a catalyst paste.

  When the catalyst paste contains a solid acid and a liquid electrolyte, the blending amount of the solid acid and the liquid electrolyte is preferably 1:50 to 10: 1 by mass ratio, more preferably 1:50 to 1: 5. It is.

  As the substrate, the same substrate as described in Embodiment 1 can be used. Especially, the polymer film comprised from PTFE and polyester is more preferable from the point of the dimensional stability in the manufacturing process of a catalyst layer, and peelability. Moreover, in order to improve the peelability from the catalyst layer, a substrate such as a polymer film provided with a release layer, a release layer or the like may be used.

As the coating amount of the catalyst paste, for example, when platinum-supported carbon is used, the platinum-supported amount is preferably 0.1 to 3.0 mg / cm ² , more preferably 0.1 to 1.5 mg / cm ² . is there.

  The method of applying the catalyst paste to the electrolyte membrane or the substrate is not particularly limited, and for example, screen printing, blade coating, die coating, spray coating, dispenser coating, ink jet coating, or the like is used. Can do. Of these, it is preferable to use screen printing or blade coating because of the ease of preparation of the catalyst paste.

  Moreover, in the above, drying temperature is 50-300 degreeC, for example, Preferably it is 100-250 degreeC. If the drying temperature is lower than 50 ° C, the solvent contained in the catalyst paste may not be removed. On the other hand, when the drying temperature exceeds 300 ° C., the binder may be thermally decomposed. The drying time is, for example, 10 minutes to 5 hours, preferably 10 minutes to 3 hours. Examples of the drying method include natural drying, far-red drying, hot air drying, reduced pressure drying, and heating.

  In the above, the heat press process is not particularly limited, and can be performed by various press processes. Moreover, the pressure at the time of hot pressing is not particularly limited, but is usually 0.5 to 10 MPa, preferably 1 to 10 MPa, for example. Moreover, the temperature at the time of hot pressing is not particularly limited, but is usually 30 to 200 ° C., preferably 50 to 250 ° C., for example. Moreover, what is necessary is just to determine suitably the press time at the time of hot-pressing according to temperature, for example, normally 10 to 240 second, Preferably it is 30 to 180 second.

  According to this embodiment, it is possible to provide a catalyst layer-electrolyte membrane laminate that can stably maintain good power generation performance for a long period of time in a high temperature and non-humidified state.

[Embodiment 3]
Hereinafter, a membrane electrode assembly will be described as Embodiment 3 of the present invention.

(Membrane electrode assembly)
FIG. 3 is a schematic cross-sectional view showing an example of a membrane electrode assembly according to Embodiment 3 of the present invention. As shown in FIG. 3, the membrane / electrode assembly 30 according to Embodiment 3 of the present invention includes the electrolyte membrane 10, the pair of catalyst layers 6 and 7, and the pair of gas diffusion layers 8 and 9 shown in Embodiment 1. The catalyst layers 6 and 7 and the gas diffusion layers 8 and 9 are respectively laminated in this order on both main surfaces of the electrolyte membrane 10. In FIG. 3, the same parts as those in FIGS. 3 and FIGS. 1 to 2 have the same functions.

  The gas diffusion layers 8 and 9 are made of a conductive material having gas diffusibility, such as a porous body, so that fuel gas or oxidant gas can flow therethrough.

  The thicknesses of the gas diffusion layers 8 and 9 may be appropriately determined in consideration of the thickness of the catalyst layer and the electrolyte membrane. The thickness is normally 100 to 400 μm, for example, and preferably 150 to 350 μm.

  As the gas diffusion layer, for example, carbon paper, carbon cloth, carbon felt or the like is used. Moreover, you may use what performed the water-repellent process to these. Further, it is desirable to use a gas diffusion layer provided with a planarization layer in order to prevent the catalyst paste from penetrating into the gas diffusion layer when the catalyst paste is applied to the gas diffusion layer.

  The membrane electrode assembly 30 can be manufactured as follows, for example. First, a catalyst paste similar to that described in the second embodiment is applied on the main surfaces of the gas diffusion layers 8 and 9, and dried to form a catalyst layer, whereby gas diffusion electrodes 16 and 17 are obtained. Next, the gas diffusion electrodes 16 and 17 are arranged on both main surfaces of the electrolyte membrane 10 so that the main surfaces of the catalyst layers 6 and 7 and the main surface of the electrolyte membrane 10 are in contact with each other, and from both sides of the obtained laminate. A hot pressing process such as hot pressing is performed to obtain the membrane electrode assembly 30. The gas diffusion electrode arranged on the cathode side becomes the cathode side catalyst electrode 16, and the gas diffusion electrode arranged on the anode side becomes the anode side catalyst electrode 17.

  In the above, when the catalyst layer contains a liquid electrolyte, the catalyst layer may be formed using a catalyst paste containing a liquid electrolyte. Alternatively, after forming a catalyst layer on the main surface of the gas diffusion layer using a catalyst paste that does not contain a liquid electrolyte to obtain a gas diffusion electrode, on the main surface of the gas diffusion electrode (on the main surface of the catalyst layer) A liquid electrolyte may be included in the catalyst layer by applying a liquid electrolyte to the catalyst layer.

  The application of the catalyst paste to the gas diffusion layer can be performed by the same method as the method of applying the catalyst paste to the base material when forming the catalyst layer in the second embodiment. Further, the drying and hot pressing treatments can be performed under the same conditions as the drying and hot pressing at the time of forming the catalyst layer in the second embodiment, respectively.

The amount of catalyst paste applied to the gas diffusion layer is, for example, when platinum-supported carbon is used, the platinum-supported amount is preferably 0.1 to 3.0 mg / cm ² , more preferably 0.1 to 0.1 mg / cm ² . 1.5 mg / cm ² .

  According to this embodiment, it is possible to provide a membrane electrode assembly that can stably maintain good power generation performance for a long period of time in a high temperature and non-humidified state.

[Embodiment 4]
Hereinafter, a fuel cell will be described as Embodiment 4 of the present invention.

(Fuel cell)
FIG. 4 is a schematic cross-sectional view showing an example of a fuel cell according to Embodiment 4 of the present invention. As shown in FIG. 4, the fuel cell 40 according to Embodiment 4 of the present invention includes an electrolyte membrane 10, a pair of catalyst layers 6, 7, a pair of gas diffusion layers 8, 9, and a pair of separators 28, 29. The catalyst layers 6, 7, the gas diffusion layers 8, 9, and the separators 28, 29 are laminated in this order on both main surfaces of the electrolyte membrane 10. In FIG. 4, the same parts as those in FIGS. 1 to 3 are denoted by the same reference numerals, and redundant description is omitted. 4 and FIGS. 1 to 3 have the same functions.

  The separator 29 is for supplying fuel to the anode side catalyst electrode 17, and has a fuel flow path 21 for circulating the fuel. On the other hand, the separator 28 is for supplying an oxidant gas to the cathode side catalyst electrode 16 and has an oxidant gas flow path 22 for circulating the oxidant gas.

  The material of the separators 28 and 29 may be any material having stable conductivity even in the environment inside the fuel cell 40. In general, a carbon plate having a flow path is used. Further, the separators 28 and 29 are made of a metal such as stainless steel, and a film made of a conductive material such as chromium, a platinum group metal, an oxide of a platinum group metal, or a conductive polymer is formed on the surface of the metal. It may be.

  The separators 28 and 29 can function as a current collector when used in a fuel cell in which a plurality of fuel cells 40 are stacked.

<Operating principle of fuel cell>
A fuel capable of supplying hydrogen, such as hydrogen gas or methanol, is supplied to the anode-side catalyst electrode 17 through the fuel flow path 21, and protons (H ⁺ ) and electrons (e ⁻ ) are generated from the fuel. The generated protons are conveyed to the cathode side catalyst electrode 16 by the electrolyte membrane 10. On the other hand, an oxidant gas such as air or oxygen gas is supplied to the cathode side catalyst electrode 16 through the oxidant gas flow path 22, and protons carried by the electrolyte membrane 10 and electrons and oxidant gas coming from the external circuit 23. Reacts to produce water. In this way, it functions as a fuel cell.

  The fuel cell 40 according to the present embodiment is formed by sequentially stacking the catalyst electrodes 16 and 17 and the separators 28 and 29 on both main surfaces of the electrolyte membrane 10 by using a known technique used for manufacturing a fuel cell. Can be manufactured.

  According to the present embodiment, by using an electrolyte membrane that can stably maintain good power generation performance for a long period of time in a high temperature and non-humidified state, it is possible to provide a fuel cell with excellent stability and high performance.

  Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited to these examples, and various modifications can be made without departing from the scope of the present invention.

Example 1
<Polybenzimidazole>
Polybenzimidazole is produced as described below with reference to the production methods described in US Pat. No. 3,313,783, US Pat. No. 3,509,108, US Pat. No. 3,555,389, US Pat. No. 4,483,997, and the like. did. To 56.35 g (0.263 mol) of 3,3 ′, 4,4′-tetraaminobiphenyl (3,3 ′, 4,4′-tetraaminobiphenyl, Aldrich), isophthalic acid (isophthalic acid, Wako) ) 43.69 g (0.263 mol) and 0.6 g of triphenyl phosphate (manufactured by Wako) were added to the flask and mixed. The flask was purged with nitrogen, and the mixture was rapidly heated to 415 ° C. while stirring with a stirrer for about 1 hour, and further stirred at 415 ° C. for 1 hour. The obtained composite was cooled to room temperature to obtain polybenzimidazole.

<Solid acid>
A metal phosphate prepared as follows was used as the solid acid. First, tin oxide (SnO ₂ , manufactured by Nano Tec) 13.56 g (0.09 mol), indium oxide (In ₂ O ₃ , manufactured by Nacalai Tesque) 1.40 g (0.0050 mol), and phosphoric acid 27.9 g (0.212 mol) of diammonium hydrogen (manufactured by Nacalai Tesque) was added and mixed. The obtained mixture was put into a crucible, fired at about 650 ° C. for about 2 hours, and the resulting product was pulverized with an agate nail to obtain tin phosphate. The obtained tin phosphate was a pyrophosphate salt partially doped with indium (Sn _0.9 In _0.1 P ₂ O ₇ ).

<Binder>
As a binder, M.I. L. A sulfonated polyetheretherketone (hereinafter also referred to as SPEEK) synthesized as described below based on the method described in Di Vona et al, Polymer 46 (2005), pages 1754-1758 was used. First, 5 g of polyetheretherketone (manufactured by VICTREX) and 250 ml of 96% concentrated sulfuric acid were placed in a 500 ml round bottom flask equipped with a reflux condenser and kept at 50 ° C. in an oil bath and refluxed for 18 hours while stirring. I let you. Then, it filtered with the glass filter and wash | cleaned the reaction solid substance with the pure water. Washing was repeated until the filtrate became nearly neutral, then dried at 50 ° C. for 24 hours, and then vacuum dried at 60 ° C. for 6 hours to obtain SPEEK.

  1 g of the obtained SPEEK and 9 g of DMA (N′N-dimethylacetamide) were mixed and stirred at room temperature for about 3 hours to prepare a 10 mass% SPEEK solution.

<First Layer-Forming Electrolyte Composition>
5 g of a 10 mass% SPEEK solution was added to 5 g of the tin phosphate obtained above, and dispersed with a disperser to prepare a first layer-forming electrolyte composition.

<Second layer forming resin composition>
1 g of PBI obtained above was added to 33 g of N, N-dimethylacetamide, and the mixture was stirred and dissolved in an oil bath to obtain a second layer-forming resin composition.

<Preparation of electrolyte membrane>
The second layer-forming resin composition obtained above was applied onto a PET film (thickness 50 μm) with a blade coater and dried at about 120 ° C. for about 30 minutes to obtain a PBI film having a thickness of 50 μm. Next, the PET film is peeled from the PBI film, and immersed in an 85% by mass phosphoric acid (H ₃ PO ₄ ) aqueous solution at room temperature for 10 minutes, so that the PBI film has a phosphoric acid doping rate of 200% by mass, A second layer 2 was formed. Next, on both main surfaces of the second layer 2, the first layer-forming electrolyte composition obtained above is applied and dried, and the first layers 1a and 1b each having a thickness of 20 μm are formed. An ion conductive electrolyte membrane was obtained.

<Preparation of membrane electrode assembly>
Platinum-supported carbon (“TEC10E50E”, manufactured by Tanaka Kikinzoku Co., Ltd.) 1 g, binder (“Nafion2020CS”, manufactured by DuPont) 2.5 g, solvent (mixed n-butanol and t-butanol at a mass ratio of 1: 1) 6.0 g was mixed and mixed with a disperser for about 3 hours to prepare a catalyst paste. The obtained catalyst paste was applied on a gas diffusion layer (“SGL34BC”, manufactured by SGL Carbon Co., Ltd.) with a blade coater so that the amount of platinum supported was about 0.5 mg / cm ^2. The catalyst layer was formed by drying for a minute to obtain a gas diffusion electrode. Next, the obtained gas diffusion electrode is arranged on both main surfaces of the electrolyte membrane obtained above so that the main surface of the catalyst layer is in contact with the main surface of the electrolyte membrane, and the obtained laminate is disposed from both sides. A membrane electrode assembly was obtained by hot pressing under conditions of 160 ° C. and 3 MPa.

(Example 2)
Electrolyte membrane and membrane electrode assembly in the same manner as in Example 1, except that the PBI film was immersed in an 85 mass% phosphoric acid aqueous solution for 5 minutes at room temperature, and the doping rate of phosphoric acid into the PBI film was changed to 150 mass%. Got.

(Example 3)
<Solid acid>
As the solid acid, a composite of cesium dihydrogen phosphate (CsH ₂ PO ₄ ) and silicon phosphate (SiP ₂ O ₇ ) prepared as follows was used.

First, cesium dihydrogen phosphate (CsH ₂ PO ₄ ) was produced as follows. 28.4 g (0.09 mol) of cesium carbonate (Cs ₂ CO ₃ , manufactured by Aldrich) and 10 g of water were placed in a beaker and stirred with a stirrer. Subsequently, 20.1 g (0.17 mol) of 85 mass% phosphoric acid aqueous solution was added dropwise little by little while stirring with a stirrer. Then, it dried at about 120 degreeC on the hotplate for about 2 hours, and water was evaporated. The obtained product was put into a crucible, dried at about 120 ° C. for about 3 days, and the obtained product was pulverized with an agate nail to obtain cesium dihydrogen phosphate (CsH ₂ PO ₄ ).

Next, silicon phosphate (SiP ₂ O ₇ ) was produced as follows. 8.0 g (0.13 mol) of silicon dioxide (SiO ₂ , manufactured by Tosoh Silica) and 38.4 g (0.33 mol) of 85% by weight aqueous phosphoric acid solution were placed in an agate noodle and mixed until it became a candy-like shape. . After that, the obtained mixture was put into an alumina crucible, and calcined at 100 to 200 ° C. for about 60 hours, and then calcined at about 700 ° C. for about 4 hours. By grinding, silicon phosphate (SiP ₂ O ₇ ) was obtained.

Finally, 2.0 g (0.0087 mol) of cesium dihydrogen phosphate (CsH ₂ PO ₄ ) obtained above and 3.5 g of silicon phosphate (SiP ₂ O ₇ ) obtained above (0. 017 mol) was dispersed with a pot mill to obtain a composite of cesium dihydrogen phosphate and silicon phosphate (CsH ₂ PO ₄ —SiP ₂ O ₇ ).

<Preparation of electrolyte membrane and membrane electrode assembly>
An electrolyte membrane in the same manner as in Example 1 except that the first layer-forming electrolyte composition was prepared using the composite of cesium dihydrogen phosphate and silicon phosphate obtained above instead of tin phosphate. And the membrane electrode assembly was obtained.

Example 4
Example 2 except that a first layer-forming electrolyte composition was prepared using a composite of cesium dihydrogen phosphate and silicon phosphate obtained in the same manner as Example 3 instead of tin phosphate. Similarly, an electrolyte membrane and a membrane electrode assembly were obtained.

(Example 5)
<Solid acid>
A composite of tungsten phosphate and potassium hydrogen sulfate (WPA-KHSO ₄ ) was produced as follows. WPA (12 Tungsto (VI) phosphate n-hydrate, manufactured by Nacalai Tesque) was previously dried at a temperature of 60 ° C. to obtain hexahydrate (WPA · 6H ₂ O). Next, 4.5 g of the obtained tungsten phosphate hexahydrate (WPA · 6H ₂ O), 4 g of potassium hydrogen sulfate (KHSO ₄ , manufactured by Nacalai Tesque) and a ball are put in an agate pot, and a planetary ball mill (Fritche Japan) P-7) was used and mixed at 720 rpm for 10 minutes to obtain a complex of tungsten phosphoric acid and potassium hydrogen sulfate (WPA-KHSO ₄ ).

<Preparation of electrolyte membrane and membrane electrode assembly>
An electrolyte membrane and membrane in the same manner as in Example 1 except that the first layer-forming electrolyte composition was prepared using the composite of tungsten phosphoric acid and potassium hydrogen sulfate obtained in place of tin phosphate. An electrode assembly was obtained.

(Example 6)
The same procedure as in Example 2 was conducted except that a first layer-forming electrolyte composition was prepared using a composite of tungsten phosphoric acid and potassium hydrogen sulfate obtained in the same manner as in Example 5 instead of tin phosphate. Thus, an electrolyte membrane and a membrane electrode assembly were obtained.

(Example 7)
<Second layer forming resin composition>
1 g of PBI produced in the same manner as in Example 1 was added to 33 g of N, N-dimethylacetamide and dissolved by stirring in an oil bath, and then produced in the same manner as in Example 1 in the resulting solution. A second layer-forming resin composition was obtained by dispersing 0.5 g of tin phosphate.

<Preparation of electrolyte membrane and membrane electrode assembly>
An electrolyte membrane and a membrane / electrode assembly were obtained in the same manner as in Example 2 except that the second layer-forming resin composition obtained above was used.

(Example 8)
An electrolyte membrane and a membrane / electrode assembly were obtained in the same manner as in Example 7 except that the amount of tin phosphate added during the production of the second layer forming resin composition was changed to 0.25 g.

Example 9
An electrolyte membrane and a membrane / electrode assembly were obtained in the same manner as in Example 7 except that the amount of the SPEEK solution added during production of the first layer forming electrolyte composition was 2.5 g.

(Example 10)
An electrolyte membrane and a membrane / electrode assembly were obtained in the same manner as in Example 7 except that the amount of the SPEEK solution added at the time of preparing the first layer-forming electrolyte composition was 10 g.

(Example 11)
A first layer-forming electrolyte composition and a second layer-forming resin composition using a composite of cesium dihydrogen phosphate and silicon phosphate obtained in the same manner as in Example 3 instead of tin phosphate An electrolyte membrane and a membrane / electrode assembly were obtained in the same manner as in Example 7 except that was prepared.

(Example 12)
A first layer-forming electrolyte composition and a second layer-forming resin composition using a composite of cesium dihydrogen phosphate and silicon phosphate obtained in the same manner as in Example 3 instead of tin phosphate An electrolyte membrane and a membrane / electrode assembly were obtained in the same manner as in Example 8 except that was prepared.

(Example 13)
A first layer-forming electrolyte composition and a second layer-forming resin composition were prepared using a composite of tungsten phosphoric acid and potassium hydrogen sulfate obtained in the same manner as in Example 5 instead of tin phosphate. Except that, an electrolyte membrane and a membrane electrode assembly were obtained in the same manner as in Example 7.

(Example 14)
A first layer-forming electrolyte composition and a second layer-forming resin composition were prepared using a composite of tungsten phosphoric acid and potassium hydrogen sulfate obtained in the same manner as in Example 5 instead of tin phosphate. Except that, an electrolyte membrane and a membrane electrode assembly were obtained in the same manner as in Example 8.

(Example 15)
Except that 0.5 g of 85 mass% phosphoric acid aqueous solution was applied on both main surfaces (on the main surface of the catalyst layer) of the gas diffusion electrode obtained in the same manner as in Example 1, the same as in Example 1. Thus, a membrane electrode assembly was produced.

(Example 16)
A membrane / electrode assembly was produced in the same manner as in Example 1 except that 0.5 g of 85 mass% phosphoric acid aqueous solution was further added to the catalyst paste.

(Comparative Example 1)
<Preparation of electrolyte membrane>
A second layer-forming resin composition produced in the same manner as in Example 1 was coated on a PET film (thickness 50 μm) with a blade coater, dried at about 120 ° C. for about 30 minutes, and a PBI film having a thickness of 50 μm. Got. Next, the PET film is peeled from the PBI film, and immersed in an 85% by mass phosphoric acid aqueous solution at room temperature for 10 minutes to obtain a PBI film having a phosphoric acid doping rate of 200% by mass. did.

<Preparation of membrane electrode assembly>
A membrane / electrode assembly was obtained in the same manner as in Example 1 except that the electrolyte membrane obtained above was used.

(Measurement of electromotive force)
The membrane electrode assemblies obtained in the examples and comparative examples are assembled into a JARI standard cell, and power generation is performed under the condition of obtaining a constant current corresponding to a current density of 300 mA / cm ² at 160 ° C. and in a non-humidified atmosphere. Then, the current was operated for a long time, the change with time of voltage was measured, and the obtained voltage drop amount (V) after 500 hours was shown in Tables 1 to 3 below. Here, the JARI standard cell is used for basic research of PEFC and evaluation tests of PEFC materials (membranes, electrode catalysts, components, etc.) at the Japan Automobile Research Institute (JARI). It means the developed cell. Tables 1 to 3 also show each composition of the electrolyte membrane.

  From Table 1 to Table 3, Examples 1 to 1 using an electrolyte membrane in which a first layer containing a solid acid and a binder is disposed on both sides of a second layer composed of a PBI membrane impregnated with phosphoric acid. It can be seen that the membrane electrode assembly No. 16 has an excellent battery performance durability with a voltage drop amount of almost zero after 500 hours. On the other hand, in the membrane / electrode assembly of Comparative Example 1 using the electrolyte membrane composed only of the PBI membrane impregnated with phosphoric acid, the battery performance was confirmed to decrease with time. This is presumably because the outflow of phosphoric acid from the PBI film is prevented by arranging the first layer containing the solid acid and the binder on both sides of the PBI film impregnated with phosphoric acid. The

  The present invention can be suitably applied to technical fields related to an ion conductive electrolyte membrane and a fuel cell using the same.

6, 7 Catalyst layer 8, 9 Gas diffusion layer 10 Electrolyte membrane 16 Cathode side catalyst electrode 17 Anode side catalyst electrode 20 Catalyst layer-electrolyte membrane laminate 21 Fuel channel 22 Oxidant gas channel 23 External circuit 28, 29 Separator 30 Membrane electrode assembly 40 Fuel cell

Claims (9)

An electrolyte membrane comprising a solid polymer compound having an imidazole group,
The first layer includes a solid acid and a binder,
The second layer includes a solid polymer compound having an imidazole group and a liquid electrolyte,
The electrolyte membrane according to claim 1, wherein the first layer is disposed on both main surfaces of the second layer.   The electrolyte membrane according to claim 1, wherein the solid polymer compound having an imidazole group is one or more polymer compounds selected from the group consisting of polybenzimidazole, polyimidazole, and polyvinylimidazole.   The electrolyte membrane according to claim 1 or 2, wherein the liquid electrolyte is at least one selected from the group consisting of liquid phosphoric acid, sulfuric acid, and an ionic liquid. The electrolyte membrane according to any one of claims 1 to 3, wherein the solid acid is a metal phosphate represented by the following general formula (1).
M _1-x N _x P ₂ O ₇ (1)
However, in said general formula (1), x is 0 <= x <0.5, M is from Zr, Cs, Sn, Ti, Si, Ge, Pb, Hf, Ca, Mg, W, Na, and Al. N is a kind selected from the group consisting of Al, In, B, Ga, Sc, Yb, Ce, La, Sb, Y, Nb and Mg.   The electrolyte membrane according to any one of claims 1 to 4, wherein the binder is at least one selected from the group consisting of a fluorine-based polymer, a hydrocarbon-based polymer, a fluorine-based ionomer, and a hydrocarbon-based ionomer. The electrolyte membrane according to any one of claims 1 to 5 and a pair of catalyst layers,
The catalyst layer-electrolyte membrane laminate, wherein the catalyst layers are respectively disposed on both main surfaces of the electrolyte membrane. The electrolyte membrane according to any one of claims 1 to 5, a pair of catalyst layers, and a pair of gas diffusion layers,
The membrane electrode assembly, wherein the catalyst layer and the gas diffusion layer are respectively laminated in this order on both main surfaces of the electrolyte membrane. The electrolyte membrane according to any one of claims 1 to 5, a pair of catalyst layers, a pair of gas diffusion layers, and a pair of separators,
The fuel cell, wherein the catalyst layer, the gas diffusion layer, and the separator are respectively laminated in this order on both main surfaces of the electrolyte membrane. A method for producing an electrolyte membrane comprising a solid polymer compound having an imidazole group,
Forming a resin film using the second layer-forming resin composition containing a solid polymer compound having an imidazole group, and then impregnating the obtained resin film with a liquid electrolyte to form a second layer; ,
An electrolyte membrane comprising a step of respectively forming a first layer on both major surfaces of a second layer obtained by using a first layer-forming electrolyte composition containing a solid acid and a binder Manufacturing method.

Images