JP2012064342A - Proton conductive electrolyte membrane, and catalyst layer-electrolyte membrane stack, membrane-electrode junction body and fuel cell using the membrane, and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a proton conductive electrolyte membrane that has excellent reproducibility, good formability, excellent mechanical strength and high proton conductivity under a non-humidified state, and a catalyst layer-electrolyte membrane stack, a membrane-electrode junction body and a fuel cell using the membrane, and a manufacturing method of the electrolyte membrane.SOLUTION: A proton conductive electrolyte membrane 1 includes solid acid 3 and a porous support body 2, the solid acid 3 is melted to form a melt, and the porous support body 2 is arranged in a melt of the solid acid 3. Further, a manufacturing method of the proton conductive electrolyte membrane 1 includes a process of arranging the solid acid 3 on the porous support body 2, a process of melting the solid acid 3 by applying heat treatment at a temperature lower than a temperature where the porous support body 2 melts and equal to or higher than a temperature where the solid acid 3 melts, and allowing the solid acid to infiltrate into the porous support body 2, and a process of cooling down the porous support body 2 into which the solid acid 3 is infiltrated and solidifying the solid acid 3.

Description

  The present invention relates to a proton conductive 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. Of these, efforts are being made to develop 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.

As a polymer electrolyte that conducts protons, perfluorosulfonic acid or the like that is generally known as Nafion (registered trademark) is used, but it conducts protons when the proton conduction mechanism is H ₃ O ^+. Since it is a transportation mechanism, it is necessary to provide a humidifying mechanism, which causes a problem that the system becomes complicated.

  Therefore, metal phosphates have been proposed as proton conductive electrolytes having proton conductivity in a non-humidified state (see, for example, Patent Document 1). Moreover, what doped another kind of metal to some metal phosphates is proposed (for example, refer patent document 2, 3).

  However, since the metal phosphates proposed in Patent Documents 1 to 3 are powders, the moldability is difficult, and there is a problem that the film is not formed unless a binder is added. And, when the binder is added, the proton conductivity inherent in the electrolyte is inhibited, so the proton conductivity and mechanical performance of the electrolyte membrane are in a trade-off relationship, and it is difficult to achieve both proton conductivity and membrane strength of the electrolyte membrane. There's a problem. Further, there is a problem that the mechanical performance cannot be satisfied, for example, a sufficient film strength cannot be obtained only with a binder, and the possibility of breakage or the like becomes high when forming a membrane-electrode assembly.

  On the other hand, a composite membrane in which a porous material is impregnated with an electrolyte has been proposed as an electrolyte membrane with improved membrane strength and improved mechanical performance (see, for example, Patent Documents 4 to 6).

JP 2005-294245 A JP 2008-53224 A JP 2008-53225 A JP 2002-8680 A Japanese National Patent Publication No. 11-501964 JP-A-10-92444

  However, since the metal phosphate proposed in Patent Documents 1 to 3 is a powder, it is difficult to impregnate the porous material as proposed in Patent Documents 4 to 6. There is.

  In order to solve the above-mentioned conventional problems, the present invention provides a proton conductive electrolyte membrane having excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a non-humidified state, and Provided are a catalyst layer-electrolyte membrane laminate, a membrane-electrode assembly and a fuel cell, and a production method thereof.

  The proton conductive electrolyte membrane of the present invention comprises a solid acid and a porous support, and the solid acid is melted to form a melt, and the porous support is disposed in the solid acid melt. It is characterized by.

  The catalyst layer-electrolyte membrane laminate of the present invention comprises the proton conductive electrolyte membrane of the present invention and a pair of catalyst layers, and the catalyst layers are respectively disposed on both sides of the proton conductive electrolyte membrane. It is characterized by that.

  The membrane-electrode assembly of the present invention comprises the proton conductive electrolyte membrane of the present invention and a pair of catalyst electrodes, and the catalyst electrodes are respectively disposed on both sides of the proton conductive electrolyte membrane. Features.

  The fuel cell of the present invention includes the proton conductive electrolyte membrane of the present invention, a pair of catalyst electrodes, and a pair of separators, and the catalyst electrode and the separator are respectively provided on both sides of the proton conductive electrolyte membrane. It is characterized by being sequentially laminated.

  The method for producing a proton conductive electrolyte membrane of the present invention includes a step of disposing a solid acid on a porous support, a temperature at which the solid acid is below the melting temperature of the porous support, and the solid acid is melted. Heat treatment at a temperature equal to or higher than the temperature to be melted and infiltrated into the porous support, and cooling the porous support infiltrated with the solid acid to solidify the solid acid. And

  In the present invention, the solid acid is melted to form a melt, and the porous support is disposed in the solid acid melt, thereby having excellent reproducibility and good moldability. A proton conductive electrolyte membrane having excellent mechanical strength and high proton conductivity in a non-humidified state, and a catalyst layer-electrolyte membrane laminate, a membrane-electrode assembly and a fuel cell using the same can be provided. Further, according to the production method of the present invention, a proton conductive electrolyte membrane having excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a non-humidified state can be easily obtained.

FIG. 1 is a schematic cross-sectional view showing an example of a proton conductive 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. FIG. 5 is a surface SEM photograph (a magnification of 1500 times) of the proton conductive electrolyte membrane when the solid acid is not melted. FIG. 6 is a surface SEM photograph (a magnification of 1500 times) of the proton conductive electrolyte membrane when the solid acid is melted. FIG. 7 is a cross-sectional SEM photograph (a magnification of 1500 times) of the proton conductive electrolyte membrane when the solid acid is not melted. FIG. 8 is a cross-sectional SEM photograph (1500 times magnification) of the proton conducting electrolyte membrane when the solid acid is melted. FIG. 9 is a scanning electron microscope (SEM) photograph (10,000 times) of a cross section of a porous support alone in one example of the present invention. FIG. 10 is a SEM photograph (10,000 times) of a cross section of the proton conducting electrolyte membrane in one example of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail based on the drawings. The following embodiments 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 to do. The technical idea of the present invention can be variously modified within the scope of the claims.

  In the present invention, the “solid acid” means a solid that exhibits acid characteristics.

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

(Proton conducting electrolyte membrane)
FIG. 1 is a schematic cross-sectional view showing an example of a proton conductive electrolyte membrane according to Embodiment 1 of the present invention. As shown in FIG. 1, the proton conductive electrolyte membrane 1 includes a solid acid 3 and a porous support 2, and the solid acid 3 is melted to form a melt, and the porous support 2 is the above-described solid acid. 3 in the melt. That is, in the present invention, the proton-conducting electrolyte membrane uses a property that a solid acid melts, and is composed of a molten solid acid and a porous support, and is a solid acid that is an electrolyte. The porous support as a reinforcing material is arranged in the melt formed by melting the melt, and the exposed solid surface including the inner surface of the pores of the porous support is coated with the molten solid acid. It constitutes a proton conducting electrolyte membrane. In the present invention, from the viewpoint of the mechanical strength and the denseness of the membrane, the exposed surface including the inner surfaces of all the pores of the porous support is coated with a molten solid acid, and the proton conductive electrolyte is coated. It is preferable to constitute a film.

  The thickness of the proton conductive electrolyte membrane 1 is not particularly limited, and is usually about 20 to 1000 μm, and preferably about 30 to 300 μm from the viewpoint of strength.

  In the proton conductive electrolyte membrane 1, the solid acid 3 is melted to form a melt. The melt formed by melting the solid acid 3 can be determined by, for example, an SEM photograph. For example, the surface SEM photograph of the proton conductive electrolyte membrane 1 when the solid acid of FIG. 5 is not melted and the surface SEM photograph of the proton conductive electrolyte membrane 1 of FIG. 6 when the solid acid is melted. As can be seen from FIG. 5, the solid acid 3 maintains the particle shape in FIG. 5, whereas in FIG. 6, the solid acid 3 does not maintain the particle shape. ing. 7 is compared with the cross-sectional SEM photograph of the proton conductive electrolyte membrane 1 when the solid acid is not melted and the cross-sectional SEM photograph of the proton conductive electrolyte membrane 1 when the solid acid is melted in FIG. As can be seen from FIG. 7, the solid acid 3 is agglomerated and voids are conspicuous, but in FIG. 8, the solid acids are connected to each other to form a rod-like crystal.

<Solid acid>
The solid acid 3 is not particularly limited as long as the melting point is lower than the melting temperature of the porous support 2. Although it depends on the porous support 2 used in combination, the solid acid 3 preferably has a melting point of 300 ° C. or less from the viewpoint of simplicity of operation. From the viewpoint of proton conductivity, it is preferable to use a solid acid having proton conductivity even at a temperature not higher than the melting temperature of the solid acid in a temperature range from room temperature to 200 ° C. and in a non-humidified atmosphere. In this specification, the non-humidified atmosphere means that intentional humidification is not performed in the atmosphere where the solid acid 3 is placed.

  The solid acid 3 is preferably an inorganic solid acid from the viewpoint of heat resistance and durability of the membrane, and more preferably an inorganic salt having proton conductivity.

  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. Specifically, tin phosphate, zirconium phosphate, cesium phosphate, silicon phosphate, titanium phosphate, germanium phosphate, lead phosphate, calcium phosphate, magnesium phosphate, sodium phosphate, aluminum phosphate, tungsten phosphate A salt etc. can be mentioned. Preferably, a pyrophosphate in which a part of a metal such as tin or cesium is substituted with a doping metal element such as indium, aluminum, boron, gallium, scandium, yttrium, cerium, lanthanum, or antimony. You may use these individually or in mixture of 1 or more types.

Among these, cesium phosphate is preferable from the viewpoint of the melting temperature range and proton conductivity. Examples of the cesium phosphate include cesium dihydrogen phosphate (CsH ₂ PO ₄ ), cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ), and these, and silicon phosphate (SiP ₂ O ₇ ). For example, a complex of cesium dihydrogen phosphate and silicon phosphate (CsH ₂ PO ₄ —SiP ₂ O ₇ ), a complex of cesium dihydrogen phosphate and silicon phosphate (CsH ₅ (PO ₄ ) ₂ -SiP ₂ O ₇ ) or the like may be used. Among them, it is preferable to use cesium pentahydrogen diphosphate (CsH ₅ (PO ₄ ) ₂ ) having a melting point near 150 to 160 ° C. because it can be melted in a relatively low temperature region.

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. Examples of the heteropolyacid include phosphotungstic acid (H ₃ PW ₁₂ O ₄₀ : WPA). 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.

  As the solid acid 3, an organic solid acid may be used. The organic solid acid is not particularly limited as long as it is an organic acid having a sulfonic acid group. For example, benzenesulfonic acid, dodecylbenzenesulfonic acid, 2-naphthalenesulfonic acid, 1,5-naphthalenedisulfonic acid, 2,6-naphthalenedisulfonic acid, 1,3,6-naphthalenetrisulfonic acid, 1,3,5, Examples include 7-naphthalene tetrasulfonic acid. You may use the organic acid which has the said sulfonic acid group individually or in mixture of 1 or more types.

  The proton conductive electrolyte membrane 1 may contain, besides the molten solid acid 3, an unmelted solid acid as long as the effects of the present invention are not impaired. In this case, the solid acid that has not been melted is preferably solid acid particles, more preferably an average particle size of about 0.1 to 200 μm, and more preferably about 0.1 to 150 μm. preferable. In the present invention, the average particle size of the solid acid particles can be measured using a scanning electron microscope (SEM) or the like. In the proton conductive electrolyte membrane 1, the content of the unmelted solid acid is preferably 0 to 40% by weight with respect to the melted solid acid 3. In addition, what is necessary is just to use the above-mentioned solid acid also as a solid acid which is not fuse | melted.

<Porous support>
The porous support 2 is not particularly limited as long as it is porous having pores. For example, a porous support composed of organic fibers, inorganic fibers and the like can be used. Moreover, the form of the porous support body 2 is not specifically limited, For example, sheet | seat shape, such as a nonwoven fabric and a woven fabric, and thin film shapes, such as a membrane filter, are mentioned. Moreover, as the porous support body 2, what has acid resistance in pH 1-3 and heat resistance in about 50-300 degreeC temperature is preferable, for example. Moreover, you may have proton conductivity.

  The porous support 2 preferably has a thickness of 10 to 500 μm, more preferably 20 to 300 μm. If the thickness is less than 10 μm, the strength of the porous support 2 may be significantly reduced, and the strength as a reinforcing material for the electrolyte membrane may not be obtained. On the other hand, if it exceeds 500 μm, it becomes too thick as a reinforcing material for the electrolyte membrane, and the proton conductivity may be lowered.

  The porous support 2 preferably has a porosity of 40 to 98% by volume. More preferably, it is 60-96 volume%. When the porosity exceeds 98% by volume, the strength is remarkably lowered, and there is a possibility that it does not easily serve as a reinforcing material. On the other hand, if it is less than 40% by volume, proton conductivity may be lowered.

  In the present invention, the “porosity” is measured, for example, as follows. The porosity calculated by measuring the thickness of the porous support of a given area with a micrometer, calculating the apparent volume, then calculating the actual volume by weight and specific gravity, and subtracting the actual volume from the apparent volume Is the porosity of the porous support.

  The porous support 2 preferably has a pore diameter of 500 μm or less, more preferably 0.1 to 400 μm, and particularly preferably 0.1 to 370 μm. When the pore diameter is less than 0.1 μm, the pore diameter is small, and the electrolyte (solid acid) does not easily penetrate into the porous support, and a uniform film may not be obtained. On the other hand, if the pore diameter exceeds 500 μm, the strength of the porous support may be remarkably lowered, and the strength as a reinforcing material for the electrolyte membrane may not be obtained.

  In the present invention, the “pore diameter” is measured, for example, as follows. Five SEM photographs of the surface of the porous support are taken at a magnification of 100, the pore diameter of the porous support is measured at each N5, and the average pore diameter of the total N20 is taken as the pore diameter of the porous support.

  The porous support 2 preferably has a fiber diameter (average diameter) of 30 μm or less, more preferably 0.2 to 30 μm. If the fiber diameter is less than 0.2 μm, the strength of the porous support 2 may be significantly reduced, and the strength as a reinforcing material for the electrolyte membrane may not be obtained. On the other hand, if the thickness exceeds 30 μm, the reinforcing material for the electrolyte membrane becomes too thick, and the proton conductivity may decrease.

  The organic fiber is not particularly limited, and one that can withstand the melting temperature (melting point) of the solid acid to be melted may be appropriately selected. For example, fibrous polypropylene, polyester, polyethylene, polyamide, polyacrylonitrile, polyether sulfone, polyvinyl alcohol, polyvinyl chloride, polyphenylene sulfone, polyurethane, polytetrafluoroethylene, polytetrafluoroethylene, polyphenylene sulfide, aramid, cellulose, Examples thereof include cellulose triacetate, acrylic, polyolefin, polyurethane, polyoxymethylene and the like. The organic fiber has an advantage that a finer pore diameter can be obtained at a low cost.

  Examples of the inorganic fiber include glass fiber, carbon fiber, graphite fiber, silicon carbide fiber, alumina fiber, tungsten carbide fiber, alumina whisker, silica whisker, ceramic fiber, and metal fiber. Among these, in terms of acid resistance and heat resistance, it is preferable to use glass fibers for inorganic fibers and polyacrylonitrile fibers for organic fibers, and more preferably glass fibers.

  In the case of a porous support composed of glass fibers (hereinafter referred to as a glass fiber support), the fiber diameter (average diameter) of the glass fibers is preferably 20 μm or less, and is 0.3 to 20 μm. It is more preferable. If the fiber warp is less than 0.3 μm, the strength of the glass fiber support may be significantly reduced, and the strength as a reinforcing material for the electrolyte membrane may not be obtained. On the other hand, if it exceeds 20 μm, the reinforcing material for the electrolyte membrane becomes too thick, and there is a risk that proton conductivity may be lowered. The glass fiber support may be composed of two or more glass fibers having different fiber diameters. From the viewpoint of easy availability, it is preferable to use glass cloth or glass fiber nonwoven fabric as the glass fiber support.

  Moreover, in the said glass fiber support, when a resin component is included as a binding component which binds glass fibers, it is preferable that the content rate of the glass fiber in a glass fiber support is 50 to 98 weight%. When the glass fiber content in the glass fiber support is 50 to 98% by weight, a glass fiber support having a strength capable of serving as a reinforcing material for the electrolyte membrane is obtained.

  The binding component is not particularly limited as long as it binds glass fibers to each other, but is preferably excellent in heat resistance and acid resistance. For example, beaten cellulose, acrylic fiber, acrylic resin emulsion, fluororesin dispersion, colloidal silica, epoxy resin and the like can be used. By including a binder component in the glass fiber support to bind the glass fibers together, the mechanical properties of the porous support are improved.

  The glass fiber support preferably has a thickness of 10 to 200 μm, more preferably 20 to 150 μm. If the thickness is less than 10 μm, the strength of the glass fiber support may be significantly reduced, and the strength as a reinforcing material for the electrolyte membrane may not be obtained. On the other hand, if it exceeds 200 μm, it becomes too thick as a reinforcing material for the electrolyte membrane, and there is a possibility that proton conductivity may be lowered.

  The glass fiber support preferably has a porosity of 40 to 98% by volume. More preferably, it is 60-96 volume%. When the porosity exceeds 98% by volume, the strength is remarkably lowered, and there is a possibility that it does not easily serve as a reinforcing material. On the other hand, if it is less than 40% by volume, proton conductivity may be lowered.

  The glass fiber support preferably has a pore diameter of 500 μm or less, more preferably 0.1 to 400 μm, and particularly preferably 0.1 to 370 μm. When the pore diameter is less than 0.1 μm, the pore diameter is small, and the electrolyte (solid acid) hardly penetrates into the porous support, and there is a possibility that a uniform film cannot be obtained. On the other hand, if the pore diameter exceeds 500 μm, the strength of the porous support may be remarkably lowered, and the strength as a reinforcing material for the electrolyte membrane may not be obtained.

  The proton conductive electrolyte membrane 1 may further contain a reinforcing material, an additive, and the like as necessary within a range not impairing the effects of the present invention.

  The reinforcing material is preferably added in the form of spherical, needle-like, or chip-like particles. For example, an aramid nonwoven fabric, liquid crystal polymer, glass cloth, glass nonwoven fabric, polytetrafluoroethylene nonwoven fabric, polytetrafluoroethylene porous material , Polyphenylene sulfide resin, glass flakes, glass particles, flake glass and the like. These may be used alone or in combination of two or more. By including the reinforcing material, the mechanical properties are improved.

  As the additive, for example, a fluorine polymer, a hydrocarbon polymer, a fluorine ionomer, a hydrocarbon ionomer, an ionic liquid, a cellulose polymer, or the like can be used.

  Examples of the fluoropolymer include tetrafluoroethylene (PTFE), polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA). A fluorine-based resin or the like 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 Examples thereof include benzooxazole, polyoxadiazol, polyxylone, polyquinoxaline, polythiadiazol, polytetrazabilene, polyoxazole, polythiazole, polyvinyl pyridine and polyvinyl imidazole.

  Examples of the fluorine ionomer include perfluorosulfonic acid-based Aquivio (registered trademark) such as Nafion (registered trademark) of DuPont, Flemion (registered trademark) of Asahi Glass Co., and Aciplex (registered trademark) of Asahi Kasei Corporation. Sulfonyl fluoride vinyl ether (SFVE) -tetrafluoroethylene copolymer and the like.

  Examples of the hydrocarbon ionomer include 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, and Examples include polyphenylene sulfide sulfonic acid.

  The ionic liquid is not particularly limited as long as it does not interfere with proton conductivity, and examples thereof include fluorohydrogenate ionic liquid and diethylmethylammonium trifluoromethanesulfonic acid ionic liquid.

  Examples of the cellulose polymer include methyl cellulose, carboxymethyl cellulose, and cellulose acetate.

  The proton conductive electrolyte membrane 1 is excellent in reproducibility because the solid acid 3 is melted to form a melt, and the porous support 2 is disposed in the melt of the solid acid 3. Has moldability, excellent mechanical strength, and high proton conductivity in a non-humidified state.

(Proton conductive electrolyte membrane production method)
The proton conductive electrolyte membrane 1 is not particularly limited, but is preferably manufactured as follows, for example. Specifically, the method for producing the proton conductive electrolyte membrane 1 of the present invention includes a step of disposing a solid acid on the porous support, a temperature below the temperature at which the porous support is melted, and the above A step of heat-treating and melting at a temperature equal to or higher than a temperature at which the solid acid melts, and infiltrating (impregnating) the porous support; and cooling the porous support infiltrated with the solid acid to solidify the solid acid Process. In the present invention, “penetration (impregnation)” means that the exposed surface including the pore inner surface of the porous support is impregnated with the molten solid acid, that is, the exposure including the pore inner surface of the porous support. The surface is covered with a molten solid acid. In the present invention, from the viewpoint of the mechanical strength and denseness of the membrane, the exposed surface including the inner surface of all the pores of the porous support is impregnated with the molten solid, that is, the porous support. It is preferred that the exposed surface, including the inner pore surface of all pores of the body, is coated with a molten solid acid.

  As the solid acid and the porous support, those described above can be used.

  Moreover, it is preferable that the said solid acid is a solid acid particle from a viewpoint that it is fuse | melted and it is easy to osmose | permeate a porous support body. The solid acid particles preferably have an average particle size of about 0.1 to 350 μm, and more preferably about 0.1 to 150 μm. In the present invention, since the solid acid is melted and permeated into the porous support, a porous support having a pore diameter smaller than the particle diameter of the solid acid particles not melted can also be used.

  In addition to the solid acid that melts at a temperature lower than the melting temperature of the porous support to be used (hereinafter, also simply referred to as the melting solid acid), the melting temperature of the porous support to be used In the case of containing a solid acid that does not melt at a temperature below (hereinafter also referred to as a solid acid that does not melt), the content of the solid acid that does not melt is 0 to 40% by weight with respect to the solid acid to be melted. preferable. The solid acid particles that do not melt preferably have an average particle size of about 0.1 to 200 μm, more preferably about 0.1 to 150 μm. An average particle size of 0.1 μm is not preferred because it tends to condense and thereby tends to increase the secondary particle size. On the other hand, when the average particle size exceeds 200 μm, the voids are likely to be large during the production of the electrolyte membrane, which is not preferable.

  In the above, the heat treatment temperature is appropriately determined based on the solid acid to be melted and the melting temperature of the porous support, within a range that is lower than the melting temperature of the porous support and equal to or higher than the melting temperature of the solid acid. That's fine. For example, when cesium phosphate is used as the solid acid to be melted, the heat treatment temperature is about 140 to 300 ° C, preferably about 150 to 180 ° C. If the heat treatment temperature is lower than about 140 ° C., cesium phosphate may not melt, and if it exceeds about 300 ° C., the porous support may be thermally deteriorated. The heat treatment time is about 5 minutes to 5 hours, preferably about 10 minutes to 3 hours. In addition, the cooling temperature of the porous support infiltrated with the solid acid may be appropriately determined within a range below the temperature at which the solid acid melts. For example, when cesium phosphate is used as the solid acid to be melted, the cooling temperature is less than about 140 ° C., preferably about room temperature to about 100 ° C. The cooling time is about 5 minutes to 5 hours, preferably about 10 minutes to 3 hours.

  Moreover, after arrange | positioning a solid acid on a porous support body and providing pressing plates, such as a glass plate, on it, you may heat-process. By providing the pressing plate, there is an advantage that the molten solid acid is more easily penetrated into the porous support.

Hereinafter, the case where cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ), which is a kind of cesium phosphate, is used as the solid acid will be specifically described.

For example, when cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) is used as the solid acid particle, it is not particularly limited. The Electrochemical Society 153 (2) A339-A342 (2006) ”or“ Toshiaki Matsui, Tomokazu Kukino, Ryuji Kikuchi, and koichi Eguchi, Electrochemical Acta 51 (2006) 3719-3723 ”etc.) Thus, cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) can be produced.

Specifically, cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) can be produced, for example, as follows. Cesium carbonate (Cs ₂ CO ₃ ) and water are mixed at a predetermined ratio, and while stirring with a stirrer using a stirrer or the like, liquid phosphoric acid having a predetermined number of moles is dropped little by little, and about 100 to 150 ° C. The water is evaporated by stirring at a temperature of about 1 to 3 hours. Then, it puts into oven and is dried at the temperature of about 100-150 degreeC, for example. The drying time is, for example, about 1 day to several days. After drying, the obtained product is pulverized in an agate bowl to form a powder, and the desired cesium pentahydrogen diphosphate (CsH ₅ (PO ₄ ) ₂ ) can be obtained. The average particle diameter of the cesium pentahydrogen diphosphate is more preferably about 0.1 to 200 μm, and more preferably about 0.1 to 150 μm.

  Next, after disposing the cesium pentahydrogen diphosphate particles on the porous support, heat treatment is performed from the side provided with pressing plates such as glass plates on both sides, the cesium pentahydrogen diphosphate particles are melted, After impregnating (impregnating) the porous support, the porous support infiltrated with cesium pentahydrogen diphosphate is cooled to solidify the cesium dihydrogen phosphate, whereby a proton conductive electrolyte membrane is obtained. 1 can be obtained. The heat treatment temperature is about 140 ° C to 300 ° C, preferably about 150 to 180 ° C. The heat treatment time is about 5 minutes to 5 hours, preferably about 10 minutes to 3 hours. In addition, the cooling temperature of the porous support infiltrated with cesium dihydrogen phosphate may be appropriately determined within a range lower than the temperature at which cesium dihydrogen phosphate is melted. For example, the cooling temperature is less than about 140 ° C., preferably about room temperature to about 100 ° C. The cooling time is about 5 minutes to 5 hours, preferably about 10 minutes to 3 hours.

Hereinafter, the case where a complex of cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ) is used as the solid acid will be specifically described.

The complex of cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ) is not particularly limited, but the same published documents as described above (for example, “Toshiaki Matsui, Tomokazu Kukino, Ryuji Kikuchi, and koichi Eguchi, The Electrochemical Society 153 (2) A339-A342 (2006) ”or“ Toshiaki Matsui, Tomokazu Kukino, Ryuji Kikuchi, and koichi Eguchi, Electrochemical Acta 51 (2006) 3719-3723 ” Etc.) and the like. Cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) can be produced in the same manner as the above production method.

Silicon phosphate (SiP ₂ O ₇ ) can be produced, for example, as follows. A mixture obtained by blending silicon dioxide (SiO ₂ ) and liquid phosphoric acid in a predetermined number of moles is put in an agate bowl and mixed until it becomes a candy-like shape. Then, it puts into an alumina crucible and fires at a temperature of about 100 to 700 ° C. The firing time is, for example, about 30 to 80 hours. After firing, the resulting product can be pulverized in an agate bowl to obtain the desired silicon phosphate (SiP ₂ O ₇ ). The average particle size of the silicon phosphate (SiP ₂ O ₇ ) is more preferably about 0.1 to 200 μm, and further preferably about 0.1 to 150 μm.

Next, a complex of cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ) can be produced as follows. Cesium pentahydrogen diphosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ) obtained as described above are blended in a predetermined number of moles. The obtained mixture is dispersed with a pod mill or the like. The dispersion time is, for example, about 1 hour to 30 hours. The amount of the diphosphate five cesium hydrogen _{(CsH 5 (PO 4) 2} ) and silicon phosphate (SiP ₂ O ₇₎ is a molar ratio of 1: 4 to 2: 1.

In the above, a planetary ball mill, a ball mill, or the like may be used as a disperser for dispersing a mixture of cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and silicon phosphate (SiP ₂ O ₇ ).

Next, after a composite of cesium dihydrogen phosphate and silicon phosphate (CsH ₅ (PO ₄ ) ₂ —SiP ₂ O ₇ ) is placed on the porous support, a pressing plate such as a glass plate is provided on both sides. Then, the porous support in which the cesium dihydrogen phosphate is melted and infiltrated (impregnated) into the porous support and then infiltrated with the cesium dihydrogen phosphate is subjected to heat treatment from above. The proton conductive electrolyte membrane 1 can be obtained by solidifying cesium dihydrogen phosphate by cooling The heat treatment temperature is about 140 ° C to 300 ° C, preferably about 150 to 180 ° C. The heat treatment time is about 5 minutes to 5 hours, preferably about 10 minutes to 3 hours. In the above heat treatment, silicon phosphate (SiP ₂ O ₇ ) does not melt. In addition, the cooling temperature of the porous support infiltrated with cesium dihydrogen phosphate may be appropriately determined within a range lower than the temperature at which cesium dihydrogen phosphate is melted. For example, the cooling temperature is less than about 140 ° C., preferably about room temperature to about 100 ° C. The cooling time is about 5 minutes to 5 hours, preferably about 10 minutes to 3 hours.

  In the above, when the solid acid contains a solid acid that melts and a solid acid that does not melt, a porous support having a different pore diameter can be appropriately used depending on the type of solid acid particles that do not melt.

  According to the above method for producing a proton-conducting electrolyte membrane, the solid acid is melted by heat treatment at a temperature lower than the melting temperature of the porous support, and then permeated into the porous support. And a porous support, easily provide a proton conductive electrolyte membrane having excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a non-humidified state. be able to.

[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 10 according to Embodiment 2 of the present invention includes the proton conductive electrolyte membrane 1 shown in Embodiment 1 and a pair of catalyst layers 6, 7. Catalyst layers 6 and 7 are respectively disposed on both surfaces of the proton conductive electrolyte membrane 1. In FIG. 2, the same parts as those in FIG. 2 and 1 have the same function.

<Catalyst layer>
The catalyst layers 6 and 7 in the present embodiment are not particularly limited as long as the layers contain a catalyst. Further, one of the catalyst layer 6 and the catalyst layer 7 becomes a cathode side catalyst layer, and the other one becomes an anode side catalyst layer.

  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, metal-supported carbon such as iron-cobalt-nickel-supported carbon, platinum black, platinum-ruthenium black, platinum- Examples thereof include fine metal particles such as cobalt black, gold black and silver black, and 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 preferably contain a solid acid in addition to the catalyst. As the solid acid, those described above can be used. Moreover, the catalyst layers 6 and 7 may contain a binder. The catalyst layers 6 and 7 can be molded only with a solid acid such as a metal phosphate and a catalyst, but by applying and molding a paste obtained by adding a binder to these, a catalyst having excellent mechanical strength. A layer can be obtained. The binder is not particularly limited as long as it has binding properties. For example, the additive shown in Embodiment 1, for example, a fluorine-based polymer, a hydrocarbon-based polymer, a fluorine-based ionomer, a hydrocarbon-based ionomer, an ionic liquid, a cellulose-based polymer, or the like can be used.

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

  The catalyst layer-electrolyte membrane laminate 10 according to the present embodiment is manufactured by applying a paste-like catalyst on both surfaces of the proton conductive electrolyte membrane 1 and performing heat treatment to form the catalyst layers 6 and 7. Can do.

The coating amount of the catalyst paste, for example, when using a platinum-supported carbon, about 0.1 to 1.0 mg / cm ² of about the amount of supported platinum, preferably on the order of about 0.3~0.6mg / cm ² is there.

  The method for applying the catalyst paste onto the proton conductive electrolyte membrane 1 is not particularly limited, and for example, screen printing, blade coating, die coating, spray coating, dispenser coating, ink jet coating, or the like may be used. it can. Of these, it is preferable to use screen printing or blade coating because of the ease of production of the catalyst paste.

  The heat treatment temperature is, for example, about 50 to 300 ° C, preferably about 100 to 250 ° C. When the heat treatment temperature is lower than about 50 ° C., the solvent contained in the catalyst paste cannot be removed, and when phosphoric acid is contained, the water contained in phosphoric acid cannot be removed. On the other hand, when the heat treatment temperature exceeds about 300 ° C., the binder may be thermally decomposed, and when phosphoric acid is contained, phosphoric acid volatilizes, which is not preferable. The heat treatment time is, for example, about 10 minutes to 5 hours, preferably about 10 minutes to 3 hours.

  According to this embodiment, it is possible to provide a catalyst layer-electrolyte membrane laminate having excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a 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 20 according to Embodiment 3 of the present invention includes the proton conductive electrolyte membrane 1 shown in Embodiment 1 and a pair of catalyst electrodes 16 and 17. Catalyst electrodes 16 and 17 are disposed on both sides of the proton conductive electrolyte membrane 1, respectively. In FIG. 3, the same parts as those in FIG. 3 and FIG. 1 have the same functions.

  The catalyst electrodes 16 and 17 are made of a catalyst and a conductive material having gas diffusibility, such as a porous body, so that fuel gas or oxidant gas can flow therethrough. The anode electrode side catalyst electrode 17 is a fuel electrode, and the cathode electrode side catalyst electrode 16 is an oxidant electrode. A catalytic metal that promotes an oxidation reaction of hydrogen is attached to the fuel electrode, and a catalytic metal that promotes a reduction reaction of oxygen is attached to the oxidant electrode.

  The thickness of the catalyst electrodes 16 and 17 may be appropriately determined in consideration of the type of electrode base material, the thickness of the electrolyte membrane, and the like. The thickness is, for example, about 20 to 3000 μm, preferably about 30 to 2000 μm.

  The catalyst electrodes 16 and 17 may be composed of two layers, a gas diffusion layer and a catalyst layer. As the gas diffusion layer, a known material such as carbon paper, carbon cloth, or carbon felt may be used. Moreover, you may use what performed the water-repellent process to said well-known material. Further, a gas diffusion layer provided with a flattening layer may be used in order to prevent penetration when a catalyst paste is applied to the gas diffusion layer.

  The membrane-electrode assembly 20 according to the present embodiment can be manufactured by using the proton conductive electrolyte membrane 1 shown in the first embodiment and forming the catalyst electrodes 16 and 17 on both surfaces thereof by pressure bonding or the like. .

  According to this embodiment, it is possible to provide a membrane-electrode assembly having excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a 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 30 according to Embodiment 4 of the present invention includes a proton conductive electrolyte membrane 1 shown in Embodiment 1, a pair of catalyst electrodes 16 and 17 shown in Embodiment 3, and a pair of Separators 28 and 29, and the catalyst electrodes 16 and 17 and the separators 28 and 29 are sequentially laminated on both surfaces of the proton conductive electrolyte membrane 1. In FIG. 4, the same parts as those in FIGS. 1 and 3 are denoted by the same reference numerals, and redundant description is omitted. 4 and FIG. 1 and FIG. 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 separators 28 and 29 may be made of any material that has stable conductivity even in the environment inside the fuel cell 30. In general, a carbon plate having a flow path is used. The separators 28 and 29 are made of a metal such as stainless steel, and a coating made of a conductive material such as chromium, a platinum group metal or oxide thereof, or a conductive polymer is formed on the surface of the metal. Also good.

  The separators 28 and 29 can have a function as a current collector when used in a fuel cell in which a plurality of fuel cells 30 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 transported to the cathode side catalyst electrode 16 by the proton conductive electrolyte membrane 1. 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 proton conductive electrolyte membrane 1 and electrons coming from the external circuit 23 and Reaction with the oxidant gas produces water. In this way, it functions as a fuel cell.

  The fuel cell 30 according to the present embodiment is formed by sequentially stacking the catalyst electrodes 16 and 17 and the separators 28 and 29 on both surfaces of the proton conductive electrolyte membrane 1 using a known technique used for manufacturing a fuel cell. Can be manufactured.

  According to the present embodiment, excellent stability is achieved by using the proton conductive electrolyte membrane 1 having excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a non-humidified state. A high-performance fuel cell 30 can be provided.

  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]
<Preparation of solid acid>
As a solid acid, cesium phosphoric acid (CsH ₅ (PO ₄ ) ₂ ) was prepared as follows. First, 15.6 g (0.048 mol) of cesium carbonate (Cs ₂ CO ₃ : manufactured by Aldrich) and 10 g of water were placed in a beaker with a stirrer and stirred with a stirrer. Subsequently, 22.1 g (0.192 mol) of 85% 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. Thereafter, the obtained product was put into a crucible, dried at about 120 ° C. for about 3 days, and the product obtained after drying was pulverized in an agate bowl, and cesium phosphate (CsH) having an average particle size of 125 μm. ₅ (PO ₄ ) ₂ ) was obtained.

<Formation of proton conductive electrolyte membrane>
0.5 g of the cesium phosphate (CsH ₅ (PO ₄ ) ₂ ) obtained above was uniformly placed on a glass fiber support having a thickness of 110 μm, a porosity of 95%, a fiber diameter of 10 μm, and a pore diameter of 100 μm, and about It was melted at 170 ° C. for about 90 minutes, and a proton conductive electrolyte membrane composed of molten cesium phosphoric acid and a glass fiber support and having a thickness of 180 μm was obtained.

[Example 2]
0.5 g of cesium phosphoric acid (CsH ₅ (PO ₄ ) ₂ ) obtained in the same manner as in Example 1 was uniformly applied to a glass fiber support having a thickness of 60 μm, a porosity of 96%, a fiber diameter of 10 μm, and a pore diameter of 200 μm. And heated at about 170 ° C. for about 90 minutes to obtain a proton conductive electrolyte membrane composed of molten cesium phosphate and a glass fiber support and having a thickness of 230 μm.

[Example 3]
0.5 g of cesium phosphoric acid (CsH ₅ (PO ₄ ) ₂ ) obtained in the same manner as in Example 1 was uniformly applied to a glass fiber support having a thickness of 42 μm, a porosity of 85%, a fiber diameter of 2 μm, and a pore diameter of 15 μm. And heated at about 170 ° C. for about 90 minutes to obtain a proton conductive electrolyte membrane composed of molten cesium phosphate and a glass fiber support and having a thickness of 120 μm.

[Example 4]
0.5 g of cesium phosphoric acid (CsH ₅ (PO ₄ ) ₂ ) obtained in the same manner as in Example 1 was added to a polyacrylonitrile having a thickness of 28 μm, a porosity of 82%, a fiber diameter of 0.3 μm, and a pore diameter of 2.0 μm. A proton conductive electrolyte that is uniformly disposed on a fiber (PAN) support, melted at about 170 ° C. for about 90 minutes, and composed of a melted cesium phosphate and a polyacrylonitrile fiber support, with a thickness of 127 μm. A membrane was obtained.

[Example 5]
<Preparation of solid acid>
As a solid acid, a composite of cesium dihydrogenphosphate and silicon phosphate (CsH ₅ (PO ₄ ) ₂ —SiP ₂ O ₇ )) was prepared as follows.

First, in the same manner as in Example 1, cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) having an average particle diameter of 125 μm was obtained.

Next, silicon phosphate (SiP ₂ O ₇ ) was produced as follows. Silicon dioxide (SiO ₂ : manufactured by Tosoh Silica) 8.0 g (0.13 mol) and 85% phosphoric acid aqueous solution 38.4 g (0.33 mol) were placed in an agate bowl and mixed until it became a starchy candy. Thereafter, the mixture is put into an alumina crucible, calcined at about 100 to 200 ° C. for about 60 hours, then calcined at about 700 ° C. for about 4 hours, and the product obtained after firing is pulverized in an agate bowl, Silicon phosphate (SiP ₂ O ₇ ) having an average particle diameter of 39 μm was obtained.

Finally, 4.0 g (0.01 mol) of cesium dihydrogen phosphate (CsH ₅ (PO ₄ ) ₂ ) and 1.2 g (0.006 mol) of silicon phosphate (SiP ₂ O ₇ ) are dispersed in a pot mill. As a result, a complex of cesium dihydrogen phosphate and silicon phosphate (CsH ₅ (PO ₄ ) ₂ —SiP ₂ O ₇ ) was obtained.

<Formation of proton conductive electrolyte membrane>
0.5 g of the composite of cesium dihydrogen pentaphosphate and silicon phosphate (CsH ₅ (PO ₄ ) ₂ —SiP ₂ O ₇ ) obtained above is 110 μm thick, 95% porosity, 10 μm fiber diameter, fine Uniformly placed on a glass fiber support with a pore size of 100 μm, melted at about 170 ° C. for about 90 minutes, and composed of molten cesium dihydrogen phosphate, unmelted silicon phosphate and glass fiber support As a result, a proton conductive electrolyte membrane having a thickness of 190 μm was obtained.

[Example 6]
0.5 g of a complex of cesium dihydrogenphosphate and silicon phosphate (CsH ₅ (PO ₄ ) ₂ —SiP ₂ O ₇ ) obtained in the same manner as in Example 5 was obtained, and the thickness was 60 μm and the porosity was 96%. Disposed uniformly on a glass fiber support having a fiber diameter of 10 μm and a pore diameter of 200 μm, melted at about 170 ° C. for about 90 minutes, and melted cesium dihydrogen pentaphosphate and unmelted silicon phosphate and glass A proton conductive electrolyte membrane composed of a fiber support and having a thickness of 140 μm was obtained.

[Comparative Example 1]
First, in the same manner as in Example 1, cesium phosphate (CsH ₅ (PO ₄ ) ₂ ) was obtained. Next, 5 g of a 10 wt% cellulose acetate solution (“LT-35” manufactured by Daicel Chemical Industries, Ltd., solvent: acetone) as a binder was added to 5 g of the obtained cesium phosphate (CsH ₅ (PO ₄ ) ₂ ), An electrolyte paste was prepared by dispersing with a disperser. This electrolyte paste was applied onto a base film (polyethylene terephthalate (PET), thickness 50 μm) with a blade coater and dried at about 170 ° C. for about 30 minutes to obtain an electrolyte membrane having a thickness of 120 μm.

  The pore diameter and porosity of the porous support used in the examples were measured as follows.

(Measurement of pore diameter of porous support)
Five SEM photographs of the surface of the porous support were taken at a magnification of 100, the pore diameter of the porous support was measured at each N5, and the average pore diameter of the total N20 was taken as the pore diameter of the porous support.

(Porosity measurement of porous support)
The thickness of the porous support alone having a predetermined area was measured with a micrometer, and the apparent volume was calculated. Thereafter, the actual volume was calculated from the weight and specific gravity, and the porosity calculated by subtracting the actual volume from the apparent volume was defined as the porosity of the porous support.

  The electrolyte (solid acid) permeability in the electrolyte membrane of the example, the tensile rupture strength of the electrolyte membrane of the example and the comparative example, and the proton conductivity were measured and evaluated as follows, and the results are shown in Table 1 below. It was.

(Electrolyte permeability in electrolyte membrane)
SEM photographs of the porous support alone and the cross section of the electrolyte membrane were taken at a magnification of 10,000 times to confirm the permeability of the electrolyte in the electrolyte membrane.

(Measurement of tensile strength at break)
As a measurement sample, a test piece having a width of 10 mm and a length of 30 mm was prepared in the longitudinal direction (MD direction) of the electrolyte membrane. Using the small desktop tester EZ Test (manufactured by Shimadzu Corporation), the obtained measurement sample was pulled at a rate of about 1 mm / min with a grip interval of 10 mm, and the load at break (MPa) was measured twice. The average value was taken as the tensile strength at break.

(Evaluation of tensile strength at break)
Based on the result of the tensile breaking strength obtained above, the tensile breaking strength was evaluated in the following three stages.
A: The tensile strength at break is 3.0 MPa or more, and has a performance that can be used as an electrolyte membrane.
B: The tensile strength at break is 0.5 MPa or more and less than 3.0 MPa, and has a performance usable as an electrolyte membrane.
C: The tensile strength at break is less than 0.5 MPa, or is not self-supporting and is insufficient for use as an electrolyte membrane.

(Proton conductivity measurement)
The electrolyte membrane is cut out to a width of 10 mm and a length of 30 mm, and an AC impedance load is applied by an electrochemical measurement device (Solartron 12528WB type), the temperature is in the range of room temperature to 160 ° C., and proton conduction in a non-humidified atmosphere The degree was measured. Table 1 below shows the results when the temperature was 150 ° C.

(Evaluation of proton conductivity)
Based on the proton conductivity results obtained above, proton conductivity was evaluated in the following two stages.
A: Proton conductivity in a non-humidified atmosphere at 150 ° C. is 1.00 × 10 ⁻³ S / cm or more, and has a performance usable as an electrolyte membrane.
B: Proton conductivity at 150 ° C. and in a non-humidified atmosphere is less than 1.00 × 10 ⁻³ S / cm, or is not self-supporting and cannot measure the performance as an electrolyte membrane.

  FIG. 9 is a cross-sectional SEM photograph of the porous support used alone in Example 4 at a magnification of 10000 times, and FIG. 10 is a cross-sectional SEM photograph of the proton electrolyte membrane obtained in Example 4 at a magnification of 10000 times. . 9 and 10, it can be seen that in the proton electrolyte membrane of Example 4, the molten solid acid (electrolyte) 3 uniformly penetrates into the porous support 2. Although not shown, it was confirmed that the electrolyte (solid acid) 3 was melted and uniformly permeated into the porous support 2 in the proton electrolyte membranes of other examples.

  As can be seen from Table 1, in Examples 1 to 6, the tensile break strength of the proton electrolyte membrane was 0.6 MPa or more, indicating good mechanical strength characteristics. However, in Comparative Example 1, it was shown that the electrolyte membrane was not self-supporting from the base material and was insufficient in strength to be used as the electrolyte membrane.

In Examples 1 to 6, the proton electrolyte membrane has a proton conductivity of 1.0 × 10 ⁻³ S / cm or more in a non-humidified atmosphere at 150 ° C. and has a performance that can be used as an electrolyte membrane. I understood. On the other hand, the electrolyte membrane of Comparative Example 1 was shown to be insufficient in strength for measuring proton conductivity due to lack of self-supporting property.

  From the above, it was found that the conductive electrolyte membrane of the present invention has excellent reproducibility, good moldability, excellent mechanical strength, and high proton conductivity in a non-humidified state.

  The present invention can be suitably applied to a technical field related to a proton conductive electrolyte membrane using a solid acid and a fuel cell using the same.

DESCRIPTION OF SYMBOLS 1 Proton conductive electrolyte membrane 2 Porous support 3 Solid acid (molten solid acid)
6, 7 Catalyst layer 10 Catalyst layer-electrolyte membrane laminate 16 Cathode side catalyst electrode 17 Anode side catalyst electrode 20 Membrane-electrode assembly 21 Fuel flow path 22 Oxidant gas flow path 23 External circuit 28, 29 Separator 30 Fuel cell

Claims (11)

Comprising a solid acid and a porous support;
The solid acid is melted to form a melt,
A proton conductive electrolyte membrane, wherein the porous support is disposed in the solid acid melt.   The proton conductive electrolyte membrane according to claim 1, wherein the solid acid is an inorganic solid acid.   The proton conductive electrolyte membrane according to claim 1, wherein the solid acid is an inorganic salt having proton conductivity.   The proton conductive electrolyte membrane according to claim 1, wherein the solid acid has a melting point of 300 ° C. or less.   The proton conductive electrolyte membrane according to claim 1, wherein the solid acid is cesium phosphate.   The proton conductive electrolyte membrane according to claim 1, wherein the solid acid is cesium dihydrogen phosphate.   The proton conductive electrolyte membrane according to claim 1, wherein the porous support is made of glass fiber. A proton conductive electrolyte membrane according to any one of claims 1 to 7 and a pair of catalyst layers,
The catalyst layer-electrolyte membrane laminate, wherein the catalyst layers are respectively disposed on both sides of the proton conductive electrolyte membrane. A proton conductive electrolyte membrane according to any one of claims 1 to 7 and a pair of catalyst electrodes,
The membrane-electrode assembly, wherein the catalyst electrodes are respectively disposed on both sides of the proton conductive electrolyte membrane.   A proton conductive electrolyte membrane according to any one of claims 1 to 7, a pair of catalyst electrodes, and a pair of separators, wherein the catalyst electrodes and the separators are provided on both sides of the proton conductive electrolyte membrane. A fuel cell characterized by being sequentially laminated. It is a manufacturing method of the proton-conductive electrolyte membrane of any one of Claims 1-7,
Placing a solid acid on the porous support;
The solid acid is melted by heat treatment at a temperature lower than the temperature at which the porous support melts and at a temperature equal to or higher than the temperature at which the solid acid melts, and infiltrated into the porous support; And a step of solidifying the solid acid by cooling the porous support.

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