JP2011150789A - Membrane electrode assembly, and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a membrane electrode assembly and a manufacturing method of the same, which prevent mixing of a fuel and air as well as leakage of the fuel outside a battery, and enable areas of a fuel electrode and an air electrode to be designed large under the condition of a restricted fuel cell installation area. <P>SOLUTION: The membrane electrode assembly includes an electrolyte film, the fuel electrode formed on one surface of the electrolyte film, and the air electrode formed on the other surface of the electrolyte film. The assembly has, at least on one side of the same, a side face composed of a continuous surface of at least a fuel electrode end face, an electrolyte film end face and an air electrode end face, and also includes an insulated sealing layer to cover the side face. Also, there is disclosed the manufacturing method of the same. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a membrane electrode assembly capable of increasing the area of a fuel electrode and an air electrode, and capable of preventing mixing of fuel and air and leakage of fuel to the outside of a battery, and a method for manufacturing the same.

  Fuel cells can be used for a long time, allowing users to use the electronic equipment longer than before by refilling the fuel once, and even if the user runs out of the battery on the go, the fuel cell does not have to wait for charging. From the point of convenience that an electronic device can be used immediately by purchasing and replenishing it, there is an increasing expectation for practical use as a new power source for portable electronic devices that support the information society.

  In general, a fuel cell oxidizes fuel such as hydrocarbon gas, hydrogen gas, and aqueous alcohol solution at a fuel electrode, and uses an oxidation-reduction reaction in which oxygen in the air is reduced at an air electrode. Supply.

  Fuel cells are classified into a phosphoric acid type, a molten carbonate type, a solid electrolyte type, a solid polymer type, a direct alcohol type, and the like according to the classification of the electrolyte material and fuel used. In particular, solid polymer fuel cells and direct alcohol fuel cells that use an ion exchange membrane that is a solid polymer as an electrolyte material are electrolyte films that are sub-millimeter thin films, and high power generation efficiency can be obtained at room temperature. Practical application as a small fuel cell for the purpose of application to portable electronic devices is being studied.

In the direct alcohol fuel cell, when an alcohol aqueous solution is supplied to the fuel electrode, the alcohol aqueous solution in contact with the fuel electrode is oxidized and separated into a gas such as carbon dioxide and protons. For example, when methanol is used as the alcohol,
CH ₃ OH + H ₂ O → CO ₂ ↑ + 6H ⁺ + 6e ⁻
Carbon dioxide is generated on the fuel electrode side by the oxidation reaction.

Protons are transmitted to the air electrode side through the electrolyte membrane. The proton and oxygen in the air are supplied to the air electrode,
3 / 2O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O
Water is produced by the reduction reaction. At this time, electrons pass through an external electronic device (load), move from the fuel electrode to the air electrode, and can be used as electric power.

  Such a fuel electrode, an electrolyte membrane, and an air electrode, which are central members for taking out electric power, are called a membrane electrode assembly.

Generally, the electrolyte membrane is configured to have an outer periphery that is about 1 to 2 cm larger than the fuel electrode and the air electrode. This is because the electrolyte membrane is used as a diaphragm to prevent mixing of fuel and air, leakage of fuel to the outside of the cell, and electrical shorting between the fuel electrode and the air electrode. Such an outer peripheral portion of the electrolyte membrane, that is, an electrolyte membrane portion where no fuel electrode or air electrode is formed cannot contribute to the oxidation-reduction reaction even if fuel or air is supplied. Such an area of the outer peripheral portion of the electrolyte membrane is hardly regarded as a problem in a membrane electrode assembly for high power applications such as an electric vehicle power source and a household power source. This is because the area of the outer periphery of the electrolyte membrane is very small relative to the total area of the membrane electrode assembly because the area of the fuel electrode and the air electrode reaches several tens to hundreds of centimeters cm ² .

However, in the case of membrane electrode composites for use in portable electronic devices that consume power of several watts, particularly for use in portable electronic devices, the area of the fuel electrode and air electrode is about several cm ² , The area of the outer peripheral portion is very large with respect to the total area of the membrane electrode assembly.

Patent Document 1 reports a method of obtaining an electrode constituent member by forming a seal portion on the side surface of the electrode constituent member and cutting at the center of the seal portion.
JP 2001-93548 A

  In a membrane electrode assembly in which the electrolyte membrane does not have an outer peripheral portion, it is easy to cause fuel leakage by simply applying a sealant to the side surface of the membrane electrode assembly as in the past, and in particular, a liquid such as methanol aqueous solution or formic acid. When fuel is used, the liquid fuel comes into contact with the seal part and the bonding strength is weakened at the interface between the membrane electrode assembly and the seal part, and the liquid fuel leaks to the outside of the fuel cell, especially the mixture of fuel and air. Have problems that cannot be prevented sufficiently.

  The present invention solves the above problems, and in a membrane electrode assembly in which the electrolyte membrane does not have an outer peripheral portion, it is applied to a portable electronic device having a power consumption of several watts, particularly to a fuel cell mounted on a portable electronic device. In the membrane electrode assembly for the purpose of application, the fuel and air mixing and the leakage of fuel to the outside of the cell are prevented, and the area of the fuel electrode and air electrode is reduced with respect to the limited installation area of the fuel cell. An object of the present invention is to provide a membrane electrode assembly that can be designed to be large and a method for producing the same.

  The present invention is a composite comprising an electrolyte membrane, a fuel electrode formed on one surface of the electrolyte membrane, and an air electrode formed on the other surface of the electrolyte membrane, the composite The present invention relates to a membrane electrode assembly having a side surface composed of a continuous surface composed of at least a fuel extreme surface, an electrolyte membrane end surface and an air extreme surface on at least one side thereof, and an insulating sealing layer covering the side surface.

  It is preferable that the side surface has a concavo-convex shape, and it is more preferable that the concavo-convex shape is formed so that the side surface has a surface area more than twice the projected area.

  The present invention further includes a flow path plate provided adjacent to the fuel electrode, and the insulating sealing layer covers the end surface of the flow path plate and / or a part of the fuel electrode side surface. About the body.

  The membrane electrode assembly of the present invention preferably further includes a permeable membrane disposed so as to cover the flow path of the flow path plate and adjacent to the fuel electrode.

  In addition, the present invention has a side surface composed of a continuous surface composed of at least a fuel extreme surface, an electrolyte membrane end surface, and an air extreme surface on at least two opposite sides of the composite, and an insulating seal that covers the side surface The present invention relates to a membrane electrode assembly having a layer, wherein the ratio L / H of the length L to the width H of the composite is 10 or more.

  In the present invention, it is preferable that a metal conductive layer provided adjacent to the air electrode is further provided, and at least a part of the metal conductive layer is in contact with the electrolyte membrane.

  The present invention also relates to a membrane electrode composite stack in which a plurality of membrane electrode composites are arranged in parallel or substantially in parallel with two opposing sides.

  Furthermore, the present invention includes a composite cutting step of cutting a first composite having a laminated structure of a fuel electrode, an electrolyte membrane, and an air electrode to produce a second composite having a smaller area than the first composite; An insulating sealing layer forming step of forming an insulating sealing layer on a cut surface of at least a second composite.

  In the method for producing a membrane electrode assembly of the present invention, the insulating sealing layer forming step preferably includes a step of applying a precursor solution of the insulating sealing layer, and in particular, the electrolyte solution is added to the precursor solution of the insulating sealing layer. It is more preferable that a solvent capable of dissolving the film is contained, and the insulating sealing layer is formed by dissolving a part of the electrolyte film with the solvent.

  The method for producing a membrane electrode assembly of the present invention may further include a step of joining the flow path plate to the fuel electrode of the second composite after the composite cutting step. In this case, it is preferable that the precursor solution of the insulating sealing layer contains a solvent capable of dissolving the flow path plate, and a part of the flow path plate is dissolved with the solvent to form the insulating sealing layer.

  In the complex cutting step, the first complex may be cut while pressing around the cut portion of the first complex.

  According to the present invention, it is possible to increase the adhesive strength of the interface between the side surface of the membrane electrode assembly composed of the end surface of the electrolyte membrane, the fuel extreme surface, and the air extreme surface and the insulating sealing layer, and to mix fuel and air, The leakage of fuel to the outside is prevented in a timely manner. As a result, the area of the outer peripheral portion of the electrolyte membrane can be reduced as much as possible, and the area of the fuel electrode and the air electrode can be designed as large as possible even when mounted on a portable electronic device that allows only a limited mounting area. Therefore, the power of several watts class required for power consumption can be supplied.

<Embodiment 1>
FIG. 1 is a surface view schematically showing an example of a preferred configuration of the membrane electrode assembly of the present invention, and FIG. 2 is a cross-sectional view taken along the plane AA ′ of FIG. A membrane electrode assembly 100 shown in FIGS. 1 and 2 includes an electrolyte membrane 101, a fuel electrode 102 formed on one surface of the electrolyte membrane 101, and an air electrode 103 formed on the other surface of the electrolyte membrane 101. And at least an insulating sealing layer 104 formed so as to be in contact with the side surfaces formed by the end face of the fuel electrode 102, the end face of the electrolyte membrane 101, and the end face of the air electrode 103 on two opposing sides of the membrane electrode assembly. The side surface is a continuous surface composed of the end surface of the fuel electrode 102, the end surface of the electrolyte membrane 101, and the end surface of the air electrode 103. The insulating sealing layer 104 is formed so as to cover the side surface.

  As described above, the insulating sealing layer is formed on the side surface of the membrane electrode assembly including the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface, so that the outer peripheral portion of the electrolyte membrane can be stably used without being used as a diaphragm. An electrical short circuit between the fuel electrode and the air electrode can be prevented. Further, by forming the side surface of the membrane electrode assembly as a continuous surface composed of the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface, the insulating sealing layer disposed so as to cover the side surface has a uniform thickness. Therefore, local stress concentration on the side surface due to swelling or shrinkage of the insulating sealing layer due to a change in the external environment does not occur, and the adhesive strength to the side surface can be improved.

  Moreover, when cations such as iron ions and calcium ions, and anions such as chloride ions and fluorine ions come into contact with the surface of the electrolyte membrane, protons (hydrogen ions) and oxonium ions contained in the electrolyte membrane, Ion exchange occurs, and the cations and the anions are taken into the electrolyte membrane. In general, metal ions and chloride ions are known to have low mobility compared to protons and oxonium ions, and the function of conducting protons in the electrolyte membrane (proton conductivity) decreases due to the inclusion of impurity ions. The internal resistance of the membrane electrode assembly increases and the output decreases. In the present invention, the outer peripheral portion of the electrolyte membrane is not necessarily required, and further, the exposed area of the side surface of the electrolyte membrane is reduced by the insulating sealing layer, so that impurity ions are prevented from being mixed into the electrolyte membrane, and the output of the membrane electrode assembly is reduced. Long-term reliability. Hereinafter, typical aspects of each member constituting the membrane electrode assembly will be described.

(Insulating sealing layer)
The insulating sealing layer in the membrane electrode assembly of the present invention has a function of preventing mixing of fuel and air, fuel leakage, maintaining electrical insulation between the fuel electrode and the air electrode, and preventing a short circuit. The insulating sealing layer is preferably formed by applying the precursor liquid of the insulating sealing layer to a side surface composed of a continuous surface composed of the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface. By forming the insulating sealing layer by applying the precursor liquid, the film thickness of the insulating sealing layer can be controlled on a submillimeter order. For this reason, the area of the outer peripheral portion of the membrane electrode assembly can be reduced as much as possible while controlling the insulating sealing layer with a film thickness of 1 mm or less and preventing fuel leakage. The precursor liquid of the insulating sealing layer is, for example, a solution containing a resin or the like constituting the insulating sealing layer, or a monomer resin that is cured by addition of photosensitivity or a polymerization initiator.

  The material of the insulating sealing layer is not particularly limited as long as the material has good bonding property with the electrolyte membrane, and an organic polymer or an inorganic polymer can be used. As the organic polymer, for example, an epoxy resin, an acrylic resin, a polyisobutylene resin, a fluorine resin, or the like can be used. As the inorganic polymer, a silicone resin can be used.

  The precursor liquid of the insulating sealing layer preferably contains an organic solvent that dissolves or softens the electrolyte membrane. When the perfluorosulfonic acid polymer described later is used as the electrolyte membrane, the electrolyte membrane can be softened by using an alcohol solvent such as methanol or ethanol as the organic solvent. Since the bonding area with the stop layer increases, it can be firmly bonded to the electrolyte membrane. On the other hand, when using a hydrocarbon polymer, which will be described later, as the electrolyte membrane, the electrolyte membrane is once dissolved by using an organic solvent such as dimethylacetamide or tetrahydrofuran, which has higher solubility than the alcohol solvent, and is insulated and sealed. By resolidifying with the formation of the layer, it can be firmly bonded to the electrolyte membrane.

(Electrolyte membrane)
The electrolyte membrane in the membrane electrode assembly of the present invention has a function of transmitting protons from the fuel electrode to the air electrode, a function of maintaining electrical insulation between the fuel electrode and the air electrode, and preventing a short circuit. The material of the electrolyte membrane is not particularly limited as long as it has proton conductivity and electrical insulation, and a polymer membrane, an inorganic membrane, or a composite membrane can be used. Examples of the polymer membrane include Nafion (registered trademark, manufactured by DuPont), Aciplex (registered trademark, manufactured by Asahi Kasei), Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.), which are perfluorosulfonic acid electrolyte membranes. It is done. Also, styrene-based graft polymer, trifluorostyrene derivative copolymer, sulfonated polyarylene ether, sulfonated polyetheretherketone, sulfonated polyimide, sulfonated polybenzimidazole, phosphonated polybenzimidazole, sulfonated polyphosphazene. And hydrocarbon-based electrolyte membranes.

  Examples of the inorganic film include phosphate glass, cesium hydrogen sulfate, polytungstophosphoric acid, and ammonium polyphosphate. Examples of the composite film include composites of inorganic materials such as tungstic acid, cesium hydrogen sulfate, and polytungstophosphoric acid, and organic materials such as polyimide, polyether ether ketone, and perfluorosulfonic acid.

(Fuel electrode, air electrode)
The fuel electrode and air electrode in the membrane electrode assembly of the present invention are provided with a catalyst layer comprising a porous layer having at least a catalyst and an electrolyte. The catalyst for the fuel electrode decomposes fuel such as hydrogen gas or aqueous methanol solution into protons and electrons, and the electrolyte has a function of conducting the generated protons to the electrolyte membrane. The catalyst for an air electrode has a function of generating water from protons conducted through an electrolyte and oxygen in the air.

  The catalyst for the fuel electrode and the air electrode may be supported on the surface of a conductor such as carbon or titanium. In this case, the catalyst or conductor is preferably in the submicron order, and the fuel The electrolyte for the electrode and the air electrode is preferably an organic polymer material. This is because, in the manufacturing process of obtaining a membrane electrode composite by cutting a composite comprising an electrolyte membrane, a fuel electrode, and an air electrode, which will be described later, the catalyst and conductor member constituting the catalyst layer are on the order of submicrons. This is because the catalyst layer can be handled as a substantially uniform layer with respect to the cutting teeth, and even when the fuel electrode and the air electrode are cut, a membrane electrode assembly can be obtained without causing an electrical short circuit between the two electrodes.

  FIG. 3 is a diagram schematically showing an example of a preferred method for producing the membrane electrode assembly of the present invention. As shown in FIG. 3, the membrane electrode assembly of the present invention as shown in FIG. 1 includes the fuel electrode and electrolyte membrane of the first composite 301 having a laminated structure of a fuel electrode, an electrolyte membrane, and an air electrode. The second composite body 302 having a smaller area than the first composite body 301 is manufactured by cutting the air electrode, and then an insulating sealing layer is formed on the cut surface of the second composite body 302. . That is, the side surface composed of a continuous surface composed of the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface is a cut surface formed by cutting the first composite.

  In the method for producing a membrane electrode assembly of the present invention, a sufficiently large membrane electrode complex (first complex) is produced, and then the membrane electrode complex (second complex) having a desired size is separated. Therefore, it is not necessary to provide a production line for membrane electrode composites having different sizes in order to be mounted on portable electronic devices having various power consumptions. For this reason, the manufacturing cost can be significantly reduced by consolidating the production lines of complex fuel electrodes and air electrodes and the production line of the composite into one.

<Embodiment 2>
FIG. 4 is a surface view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 400 shown in FIG. 4 includes an electrolyte membrane 401, a fuel electrode 402 (not shown) formed on one surface of the electrolyte membrane 401, and an air electrode formed on the other surface of the electrolyte membrane 401. 403 and at least an insulating sealing layer 404 formed so as to be in contact with the side surface formed by the end face of the fuel electrode 402, the end face of the electrolyte membrane 401, and the end face of the air electrode 403 on two opposing sides of the membrane electrode assembly. As in the first embodiment, the side surface is a continuous surface composed of the end surface of the fuel electrode 402, the end surface of the electrolyte membrane 401, and the end surface of the air electrode 403.

  Here, in the membrane electrode assembly of the present embodiment, the side surfaces on the two sides where the insulating sealing layer 404 is provided have a mountain-shaped uneven shape when viewed from the stacking direction of the fuel electrode / electrolyte membrane / air electrode. is doing. Thus, the side surface consisting of the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface has an uneven shape, thereby increasing the adhesion area of the side surface and the insulating sealing layer, mixing of fuel and air, It is possible to effectively prevent fuel leakage to the outside of the battery.

The concavo-convex shape may not necessarily be a mountain shape, but it is more preferable that the concavo-convex shape is formed so that the side surface has a surface area that is twice or more the projected area. Here, the projected area of the side surface is an area obtained from the length and thickness of one side of the side surface, and the surface area of the side surface means an area obtained from the side length and thickness of one side of the side surface. That is, taking a mountain shape as an example, if the length of one side of the side surface is A and the thickness is B, the projected area S1 of the side surface is S1 = A × B
It is represented by When the chevron shape is an aggregate of equilateral triangles, the side length of one side of the side surface is represented by 2A, so the surface area S2 of the side surface is S2 = 2A × B.
It is represented by That is, in the case of a mountain shape, when the vertex has an inner angle of 60 ° or less, the side surface has a surface area that is twice or more the projected area.

<Embodiment 3>
FIG. 5 is a surface view schematically showing an example of another preferred configuration of the membrane electrode assembly of the present invention. The membrane electrode assembly 500 shown in FIG. 5 includes an electrolyte membrane 501, a fuel electrode 502 (not shown) formed on one surface of the electrolyte membrane 501, and the other of the electrolyte membrane 501, as in the above embodiment. Insulation seal formed so as to be in contact with the side surface formed by the end face of the fuel electrode 502, the end face of the electrolyte membrane 501, and the end face of the air electrode 503 on the two opposite sides of the air electrode 503 formed on the surface. At least a stop layer 504 is provided. The side surface is a continuous surface composed of an end surface of the fuel electrode 502, an end surface of the electrolyte membrane 501, and an end surface of the air electrode 503. Here, the ratio L / H between the length L and the width H of the membrane electrode assembly is 10 or more. Thus, by setting the ratio L / H to 10 or more and providing an insulating sealing layer on at least the side surface of the long side, the area of the outer peripheral portion of the electrolyte membrane can be further reduced, and therefore the membrane electrode assembly It is possible to design a large area of the fuel electrode and the air electrode with respect to the area.

<Embodiment 4>
FIG. 6 is a surface view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 600 shown in FIG. 6 is similar to that of the above-described third embodiment. However, an end face of a fuel electrode 602 (not shown) and an electrolyte membrane are formed on two opposing sides of the membrane electrode assembly and further on one side that intersects the two sides. The side surface is a continuous surface composed of the end surface 601 and the end surface of the air electrode 603, and the insulating sealing layer 604 is formed on these side surfaces. Thus, by forming the insulating sealing layer on the three sides, it is possible to more effectively prevent the mixing of fuel and air and the leakage of the fuel to the outside of the battery, and the exposed area of the side surface of the electrolyte membrane is further reduced. Therefore, mixing of impurity ions into the electrolyte membrane is suppressed, and the long-term reliability of the output of the membrane electrode assembly can be further improved. An insulating sealing layer may be formed on the side surface composed of the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface on all four sides of the membrane electrode assembly.

  Here, in the present invention, the width H of the membrane electrode assembly is preferably 10 mm or less. By setting the width H to 10 mm or less, oxygen in the air is easily taken in, and even if another membrane electrode composite is laminated on the air electrode of the membrane electrode composite by providing a predetermined space, the width Since H is short, it is possible to suppress a decrease in output due to lack of oxygen.

<Embodiment 5>
FIG. 7 is a surface view schematically showing an example of a stack structure (membrane electrode composite stack) in which a plurality of membrane electrode composites of the present invention are arranged. The membrane electrode composite stack shown in FIG. 7 has a predetermined distance between, for example, a membrane electrode composite 700 having a structure as shown in FIG. 12 described later in parallel or substantially parallel to the side surface on which the insulating sealing layer is provided. A plurality of them are arranged. As described above, when other membrane electrode composites are arranged in a direction without the outer peripheral portion of the electrolyte membrane, the gap between the membrane electrode composites can be widened, so that the other membrane electrode composites are laminated. However, air is easily supplied to the air electrode.

  The material constituting the insulating sealing layer in the present embodiment generates water by reacting protons, electrons, and oxygen in the air at the air electrode by taking out the output, and contacts the insulating sealing layer. A water-resistant resin is preferred. Further, when the output is increased due to the stack structure, the amount of heat generated with respect to the heat radiation area increases, and the membrane electrode assembly operates at a high temperature. For this reason, it is preferable that the material which comprises an insulating sealing layer is a heat resistant resin which has the heat resistance of about 100 degreeC. Thereby, even in a long-term operation, the function of the insulating sealing layer can be stably maintained for a long time.

<Embodiment 6>
FIG. 8 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 800 shown in FIG. 8 includes a membrane electrode assembly similar to that in Embodiment 1, and a flow path plate 805 having the same width as the membrane electrode assembly, which is disposed adjacent to the fuel electrode 802. And an insulating sealing layer 804 is provided on a side surface including the end face of the flow path plate 805, the end face of the fuel electrode 802, the end face of the electrolyte membrane 801, and the end face of the air electrode 803. The side surface includes a continuous surface composed of an end surface of the flow path plate 805, an end surface of the fuel electrode 802, an end surface of the electrolyte membrane 801, and an end surface of the air electrode 803. As described above, the laminated structure including the fuel electrode 802, the electrolyte membrane 801, and the air electrode 803 is joined to the flow path plate 805 by the insulating sealing layer 804, so that the fuel is supplied to the flow path 806 of the flow path plate 805. When supplied to the fuel, it is possible to prevent fuel leakage.

  The flow path plate in the membrane electrode assembly of the present embodiment has a function of supplying fuel to the fuel electrode. For the material of the flow path plate, use polymer materials (plastic materials) such as acrylic, ABS, polyvinyl chloride, polyethylene, polyethylene terephthalate, polyetheretherketone, and Teflon, and metal materials such as copper, stainless steel, and titanium. Can do. In particular, it is preferable to use a metal material for the material of the flow path plate, and it is more preferable to use a corrosion-resistant metal material such as stainless steel or titanium. This is because when the material of the flow path plate is metal, the effect of collecting electrons from the fuel electrode is imparted, the internal resistance of the membrane electrode assembly is reduced, and the reduction in output can be suppressed. In addition, by using a corrosion-resistant metal material, elution of metal ions from the flow path plate is suppressed, and ion exchange to the membrane electrode assembly can be suppressed. Similarly, the internal resistance of the membrane electrode assembly is reduced. It is possible to suppress this, and it is possible to suppress a decrease in output. When plastic materials such as acrylic, ABS, polyvinyl chloride, polyethylene, and polyethylene terephthalate are used as the flow path plate, diethyl ether or ethyl acetate that dissolves or softens the flow path plate is used as the precursor liquid of the insulating sealing layer. An organic solvent such as an ether compound such as acetone, a ketone compound such as acetone or methyl ethyl ketone, or an aromatic compound such as toluene or benzene is preferably contained. By using such an organic solvent, the flow path plate is once dissolved and re-solidified together with the formation of the insulating sealing layer, whereby the flow path plate can be firmly bonded.

<Embodiment 7>
FIG. 9 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 900 shown in FIG. 9 includes a flow path plate 905 having a larger width than the laminated structure including the fuel electrode 902, the electrolyte membrane 901, and the air electrode 903 adjacent to the fuel electrode 902. An insulating sealing layer 904 is provided so as to cover a side surface including an end surface, an end surface of the electrolyte membrane 901, and an end surface of the air electrode 903, and a part of the surface of the flow path plate 905 (the surface on the fuel electrode 902 side). The side surface is a continuous surface composed of the end surface of the fuel electrode 902, the end surface of the electrolyte membrane 901, and the end surface of the air electrode 903. That is, the insulating sealing layer 904 is formed so as to cover the side surface, and is in contact with the surface of the flow path plate 905 on which the laminated structure including the fuel electrode 902, the electrolyte membrane 901, and the air electrode 903 is not laminated. It is formed and covers the flow path plate surface.

  The accuracy of the width of the membrane electrode assembly depends on the accuracy of the film thickness of the insulating sealing layer because the insulating sealing layer is formed by coating. In this embodiment, since the width of the electrolyte membrane, the fuel electrode, and the air electrode is smaller than the width of the flow path plate, the insulating sealing layer is not formed beyond the width of the flow path plate, The width of the membrane electrode assembly can be adjusted with high accuracy. Controlling the width of such a membrane electrode assembly improves the accuracy of the interval between the membrane electrode assemblies when a stack structure as shown in FIG. 7 in which a plurality of membrane electrode assemblies of the present invention are arranged is constructed. This prevents the supply of oxygen in the air from being obstructed unintentionally.

<Eighth embodiment>
FIG. 10 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. The membrane electrode assembly 1000 shown in FIG. 10 uses, as a flow path plate, a flow path plate 1005 in which a groove for allowing the insulating sealing layer 1004 to permeate the surface of the fuel electrode 1002 is used. This is the same as in the sixth embodiment. That is, the insulating sealing layer 1004 covers a side surface composed of a continuous surface composed of the end surface of the fuel electrode 1002, the end surface of the electrolyte membrane 1001, and the end surface of the air electrode 1003, and the end surface of the flow path plate 1005 and the surface on the fuel electrode 1002 side. A part of is covered. As a result, the side surface of the fuel electrode 1002 and a part of the surface on the flow path plate 1005 side are bonded to the insulating sealing layer 1004, so that fuel leakage can be more effectively prevented.

<Embodiment 9>
FIG. 11 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 1100 shown in FIG. 11 is the same as Embodiment 6 except that a flow path plate 1105 having a side surface (end surface) having a mountain-shaped uneven shape is used as the flow path plate. Thereby, since the side surface of the flow path plate 1105 and the insulating sealing layer 1104 are firmly bonded, the leakage of fuel can be more effectively prevented.

<Embodiment 10>
FIG. 12 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 1200 shown in FIG. 12 includes a permeable membrane 1207 disposed between the fuel electrode 1202 and the flow path plate 1205. The osmosis membrane 1207 is formed so as to cover the flow path 1206 of the flow path plate 1205 and to be adjacent to the fuel electrode 1202. Other configurations are the same as those in the seventh embodiment. The insulating sealing layer 1204 is formed so as to cover the side surface including the end surface of the osmotic membrane 1207, the end surface of the fuel electrode 1202, the end surface of the electrolyte membrane 1201, and the end surface of the air electrode 1203, and the osmotic membrane 1207, the fuel electrode 1202, and the electrolyte membrane 1201. And the air electrode 1203 are formed so as to be in contact with the surface of the non-laminated channel plate 1205 and cover the surface of the channel plate.

  As the osmotic membrane, a membrane that allows liquid fuel to permeate and diffuse can be used. As a specific example of the osmosis membrane, a membrane used in a membrane separation process such as dialysis, reverse osmosis, and pervaporation can be used. As in the present embodiment, the leakage of fuel can be suppressed by covering the flow path of the flow path plate with the permeable membrane.

  Since the osmosis membrane can also give the function of limiting the supply rate of liquid fuel to the fuel electrode, the liquid fuel supply rate to the fuel electrode can be easily controlled by selecting the type of osmosis membrane to be used. it can. Thus, for example, an electrolyte with very high proton conductivity exhibits high solubility in liquid fuel. Therefore, even when a fuel electrode catalyst layer containing such an electrolyte is formed, the fuel electrode is formed by the osmotic membrane. The supply speed of the liquid fuel to the fuel electrode can be adjusted, and the electrolyte can be prevented from dissolving and flowing out from the catalyst layer of the fuel electrode.

  The osmotic membrane is preferably a polymer membrane, particularly an organic polymer membrane, because it is flexible and hardly cracks or breaks. Furthermore, the organic polymer membrane is a solid polymer electrolyte membrane in that the utilization efficiency of the catalyst in the fuel electrode catalyst layer in which the continuity between the electrolyte membrane and the proton conduction path is not maintained can be improved. Particularly preferred. Examples of the solid polymer electrolyte membrane include a hydrocarbon solid polymer electrolyte membrane. Hydrocarbon solid polymer electrolyte membranes have a low swelling rate with respect to contact with liquid fuel, so that stress applied to the interface with the fuel electrode and the channel plate is unlikely to occur, and fuel leakage due to separation of the osmotic membrane is suppressed. Can do. In addition, since the permeability of the liquid fuel is low, it is easy to limit the supply speed of the liquid fuel reaching the fuel electrode to a desired level even when a high concentration liquid fuel is used. Thereby, the phenomenon (namely, crossover phenomenon) which a liquid fuel permeate | transmits the electrolyte membrane of a membrane electrode assembly can be suppressed.

  Specific examples of the solid polymer electrolyte membrane include perfluorosulfonic acid, styrene-based graft polymer, trifluorostyrene derivative copolymer, sulfonated polyarylene ether, sulfonated polyether ether ketone, sulfonated polyimide, sulfonated poly Examples thereof include solid polymer electrolyte membranes having high proton conductivity such as benzimidazole, phosphonated polybenzimidazole, and sulfonated polyphosphazene. In particular, a hydrocarbon solid polymer electrolyte membrane made of one or more polymer materials selected from the group consisting of styrene graft polymers, sulfonated polyarylene ethers, sulfonated polyether ether ketones, and sulfonated polyimides is preferred.

  Further, as the osmotic membrane, for example, a polymer membrane having a functional group such as hydroxyl group, amino group, carboxyl group, sulfone group, phosphoric acid group, ether group, and ketone group may be used. Specifically, it is preferable to use a film obtained by copolymerizing a combination of polymer materials such as hydroxyethyl methacrylate, polyvinylidone, dimethylacrylamide, and glycerol methacrylate.

<Embodiment 11>
FIG. 13 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. The membrane electrode assembly 1300 shown in FIG. 13 uses a flow path plate 1305 having a concavo-convex shape on the surface of the osmotic membrane 1307 as a flow path plate, and a permeation membrane that has penetrated into the concavo-convex shape is formed. Yes. Other configurations are the same as those in the tenth embodiment. Thereby, since the adhesive force of a flow-path board and a permeable membrane becomes strong, the leakage of the fuel which flows through a flow path can fully be prevented.

<Embodiment 12>
FIG. 14 is a cross-sectional view schematically showing another preferred configuration example of the membrane electrode assembly of the present invention. A membrane electrode assembly 1400 shown in FIG. 14 includes an electrolyte membrane 1401, a fuel electrode 1402 formed on one surface of the electrolyte membrane 1401, an air electrode 1403 formed on the other surface of the electrolyte membrane 1401, and a fuel electrode. An insulating sealing layer 1404 formed so as to be in contact with the side surface formed by the end surface 1402, the end surface of the electrolyte membrane 1401, and the end surface of the air electrode 1403; and a metal conductive layer 1408 formed adjacent to the air electrode 1403. Is provided. A part of the metal conductive layer 1408 is in contact with the electrolyte membrane 1401. Other configurations are the same as those in the fourth embodiment. Thus, when the metal conductive layer is provided, electrons taken out from the fuel electrode can be uniformly supplied to the air electrode, so that the internal resistance of the membrane electrode assembly is reduced and the output can be kept high. it can.

  The metal conductive layer in the membrane electrode assembly of the present embodiment has a function of supplying electrons to the air electrode and a function of performing electrical wiring. The material of the metal conductive layer is preferably a metal material that has a small specific resistance and suppresses a decrease in voltage even when current is taken in the plane direction, has electronic conductivity, and has corrosion resistance in an acidic atmosphere. More preferable. Specifically, noble metals such as Au, Pt, and Pd, metals such as C, Ti, Ta, W, Nb, Ni, Al, Cr, Ag, Cu, Zn, and Su, and nitrides of these metals, It is preferable to use carbide or the like, or an alloy such as stainless steel, Cu—Cr, Ni—Cr, or Ti—Pt, and at least one element selected from the group consisting of Pt, Ti, Au, Ag, Cu, Ni, and W It is more preferable to contain.

  In addition, when using a metal having poor corrosion resistance in an acidic atmosphere such as Cu, Ag, Zn, in addition to noble metals and metal materials having corrosion resistance such as Au, Pt, Pd, a conductive polymer, Conductive nitride, conductive carbide, conductive oxide, etc. can be used as the surface coating. In this case, the life of the fuel cell can be extended. Further, as shown in the description of the first embodiment, when the membrane electrode assembly of the present embodiment is obtained by cutting the first composite, the metal conductive layer is made of a soft material such as Au or Cu. , Ag, Zn, Su or the like is preferably used. Thereby, the metal conductive layer can be easily cut, and a membrane electrode assembly can be obtained without causing an electrical short circuit between the fuel electrode and the air electrode. When the shape of the metal conductive layer is a foil (plate), the thickness is preferably 100 μm or less, and when the metal conductive layer is formed from a nonwoven fabric, the average fiber diameter of the fibers is preferably 100 μm or less, When the metal conductive layer is formed from foamed metal, the porosity is preferably 70% or more. Thereby, a metal conductive layer can also be easily cut | disconnected with an electrolyte membrane, a fuel electrode, and an oxygen electrode.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<Example 1>
As the electrolyte membrane, Nafion (registered trademark) 117 (manufactured by DuPont) having a size of 40 × 40 mm and a thickness of about 175 μm was used.

  The catalyst paste was prepared by the following procedure. A catalyst-supported carbon particle (TEC66E50, manufactured by Tanaka Kikinzoku Co., Ltd.) having a Pt loading amount of 32.5 wt% and a Ru loading amount of 16.9 wt%, and 20 wt% of Nafion alcohol composed of Pt particles, Ru particles and carbon particles. A solution (manufactured by Aldrich), n-propanol, isopropanol, and zirconia balls are placed in a fluorine polymer container at a predetermined ratio and mixed for 50 minutes at 500 rpm using a stirrer. An electrode catalyst paste was prepared. On the other hand, using catalyst-supported carbon particles (TEC10E50E, manufactured by Tanaka Kikinzoku Co., Ltd.) having a Pt support amount of 46.8 wt% made of Pt particles and carbon particles, A catalyst paste was prepared.

Further, on each water-repellent layer of a set of carbon paper (25BC, manufactured by SGL) having a water-repellent layer formed on one side of 23 × 23 mm, the fuel electrode catalyst paste and the air electrode the catalyst paste, each of about 3 mg / cm ² is catalyst loading, 1 mg / cm ² so as to, using a screen printing plate having a window 23 × 23 mm, that is applied and dried, a thickness of about 300μm The fuel electrode and the air electrode were formed.

  Next, the surface of the fuel electrode and the air electrode coated with the catalyst paste is in contact with the electrolyte membrane so that the positions of the fuel electrode and the air electrode overlap with the centers of the front and back surfaces of the electrolyte membrane, respectively, By performing a hot press for a minute, the fuel electrode and the air electrode were bonded to the electrolyte membrane to produce a membrane electrode assembly.

  In parallel with the two opposing sides of the membrane electrode assembly, the membrane electrode assembly surface other than the cutting portion is pressed with an acrylic plate at intervals of 2 mm, and cut perpendicularly to the membrane electrode assembly with a stainless steel blade edge. Thus, a plurality of membrane electrode composites having a width of 2 mm and a length of 40 mm were obtained.

  The obtained membrane electrode composite having a width of 2 mm is sandwiched between two acrylic plates, aligned so that the side surfaces of the acrylic plate and the cut surface of the membrane electrode composite are aligned, and the cut surface and the side surfaces of the acrylic plate After applying an epoxy resin, an acrylic squeegee was slid to apply an epoxy resin to the entire cut surface to form an insulating sealing layer. The film thickness of the obtained epoxy resin was about 100 μm, and the width of the finally obtained membrane electrode assembly was about 2.2 mm and the length was 40 mm.

  As a result of cross-sectional observation of the obtained membrane electrode assembly, it was confirmed that the epoxy resin was sufficiently bonded to each end face of the electrolyte membrane, the air electrode, and the fuel electrode.

<Example 2>
A membrane electrode assembly was produced in the same manner as in Example 1 except that a regular triangular crest-shaped cutting edge with an amplitude of 0.5 mm was used as the cutting tooth. As a result of cross-sectional observation of the obtained membrane electrode assembly, the epoxy resin was sufficiently bonded to the respective end faces of the electrolyte membrane, the air electrode, and the fuel electrode.

<Example 3>
Before applying the epoxy resin of the membrane electrode composite of Example 1 to the cut surface, the membrane electrode was applied to the channel plate having a channel shape of 0.2 mm depth, 1.0 mm width, and 2.0 mm width. The fuel electrode of the composite was brought into contact and sandwiched between two acrylic plates, and then an epoxy resin was applied and formed on the side surface consisting of the end face of the flow path plate, the fuel extreme face, the electrolyte membrane end face, and the air extreme face. A Teflon tube was connected to one of the channels of the channel plate of the obtained membrane electrode composite, and a 3 mol / L aqueous methanol solution was supplied at a rate of 0.1 ml / min with a liquid feed pump. At this time, no leakage of fuel from the portion where the flow path plate and the membrane electrode assembly were bonded by the epoxy resin was observed.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The membrane electrode assembly of the present invention, which can design the area of the fuel electrode and the air electrode larger than the limited installation area of the fuel cell and prevent the mixture of fuel and air and the leakage of fuel to the outside of the battery, It can be suitably applied to.

It is a surface view which shows typically the example of the preferable structure of the membrane electrode assembly of this invention. It is sectional drawing in the A-A 'surface of FIG. It is a figure which shows typically the example of the preferable manufacturing method of the membrane electrode assembly of this invention. It is a surface view which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is a surface view which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is a surface view which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is a surface view which shows typically the example of the stack structure (membrane electrode composite stack) which has arrange | positioned two or more the membrane electrode composites of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention. It is sectional drawing which shows typically the example of another preferable structure of the membrane electrode assembly of this invention.

Explanation of symbols

  100,400,500,600,700,800,900,1000,1100,1200,1300,1400 Membrane electrode composite, 101,401,501,601,801,901,1001,1101,1201,1301,1401 Electrolyte Membrane, 102, 402, 502, 602, 802, 902, 1002, 1102, 1202, 1302, 1402 Fuel electrode, 103, 403, 503, 603, 803, 903, 1003, 1103, 1203, 1303, 1403 Air electrode, 104, 404, 504, 604, 804, 904, 1004, 1104, 1204, 1304, 1404 Insulation sealing layer, 301 first composite, 302 second composite, 805, 905, 1005, 1105, 1205, 1305 Road plate, 806, 906, 1 006, 1106, 1206, 1306 flow path, 1207, 1307 permeation membrane, 1408 metal conductive layer.

Claims (14)

A composite comprising an electrolyte membrane, a fuel electrode formed on one surface of the electrolyte membrane, and an air electrode formed on the other surface of the electrolyte membrane,
The composite has, on at least one side thereof, a side surface comprising a continuous surface composed of at least the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface,
A membrane electrode assembly comprising an insulating sealing layer covering the side surface.   The membrane electrode assembly according to claim 1, wherein the side surface has an uneven shape.   The membrane electrode assembly according to claim 2, wherein the concavo-convex shape is formed such that the side surface has a surface area that is twice or more the projected area. A flow path plate provided adjacent to the fuel electrode;
The membrane electrode assembly according to any one of claims 1 to 3, wherein the insulating sealing layer covers an end face of the flow path plate and / or a part of the fuel electrode side surface.   The membrane electrode assembly according to claim 4, further comprising a permeable membrane disposed so as to cover the flow path of the flow path plate and adjacent to the fuel electrode. In at least two opposite sides of the composite, the composite has at least a side surface composed of a continuous surface composed of the fuel extreme surface, the electrolyte membrane end surface, and the air extreme surface,
An insulating sealing layer covering the side surface;
The membrane electrode assembly according to any one of claims 1 to 5, wherein a ratio L / H between a length L and a width H of the composite is 10 or more. A metal conductive layer provided adjacent to the air electrode;
The membrane electrode assembly according to claim 1, wherein at least a part of the metal conductive layer is in contact with the electrolyte membrane.   A membrane electrode composite stack comprising a plurality of membrane electrode composites according to claim 6 or 7 arranged in parallel or substantially parallel to the two opposing sides. Cutting a first composite having a laminated structure of a fuel electrode, an electrolyte membrane, and an air electrode to produce a second composite having a smaller area than the first composite; and
An insulating sealing layer forming step of forming an insulating sealing layer on at least the cut surface of the second composite;
The manufacturing method of the membrane electrode assembly of Claim 1 which has these.   The method for producing a membrane electrode assembly according to claim 10, wherein the insulating sealing layer forming step includes a step of applying a precursor solution of the insulating sealing layer.   The method for producing a membrane electrode assembly according to claim 11, wherein the precursor solution of the insulating sealing layer includes a solvent capable of dissolving the electrolyte membrane.   The method for producing a membrane electrode assembly according to any one of claims 9 to 11, further comprising a step of joining a flow path plate to the fuel electrode of the second complex after the complex cutting step.   The method for producing a membrane electrode assembly according to claim 12, wherein the precursor solution of the insulating sealing layer includes a solvent capable of dissolving the flow path plate.   The method for producing a membrane electrode assembly according to any one of claims 9 to 13, wherein, in the complex cutting step, the first complex is cut while pressing around a cut portion of the first complex.

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