JP2011065890A - Fuel cell and assembling method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell that is assembled with less time and efforts and is manufactured thinner, and to provide an assembling method therefor. <P>SOLUTION: A projected piece 72 is provided to an air pole sealing member. The air pole sealing member is assembled to an air pole side of a membrane electrode junction 22, in which an electrolyte membrane 26 has the air pole 32 and a fuel pole 30. A conductor 24 having a conductive layer is folded, and the membrane electrode junction 22 is sandwiched between the folded electric conductor 24. When the membrane electrode junction 22 is sandwiched by the conductor 24, the projected piece 72 that is provided to the air pole sealing member is inserted into a notch provided to the conductor 24, thus the air pole sealing member and the conductor 24 being positioned. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a direct methanol fuel cell that can be easily assembled and a method for assembling the same.

  In recent years, attempts have been made to use fuel cells as power sources for various electronic devices such as personal computers and mobile phones. Since the fuel cell has an advantage that power can be generated continuously by replenishing and replacing only the fuel, it can be said that it is extremely advantageous as a power source for portable electronic devices if it can be downsized.

  Direct methanol fuel cells (DMFCs), in particular, are expected to be put to practical use as power sources for small devices because of the high energy density of methanol, the fuel, and the ease of handling compared to hydrogen gas. .

  For example, Japanese Patent Laid-Open No. 2008-192506 (Patent Document 1) states that “in the conductive layer, one seal frame is bonded or formed in advance to the cathode conductive layer and the other seal frame is bonded to the anode conductive layer. Since the periphery of the membrane electrode assembly is defined by the frame, positioning of the membrane electrode assembly with respect to the conductive layer is easy ”(see paragraph [0040]), and a sealing material is bonded or formed in advance on the conductive layer. Describes a method for improving the assembly of the fuel cell.

  Japanese Patent Laid-Open No. 2001-319666 (Patent Document 2) states that “a liquid seal is applied in a groove formed in the outer peripheral portion in the separator surface, and the liquid seal before curing is placed around the solid polymer electrolyte membrane. The electrode film structure is sandwiched between a pair of separators in a state of being provided in close contact with the protruding portion provided around the anode side diffusion electrode and the cathode side diffusion electrode, and then heated to cure the liquid seal "(paragraph [0009] And a method in which a liquid seal is applied to the outer peripheral portion of the separator and then heat-cured in a state where the electrolyte membrane is adhered.

  Furthermore, Japanese Patent Application Laid-Open No. 2004-47397 (Patent Document 3) states that “in order to improve the airtightness of the unit cell, a groove is provided in a frame connecting body or a solid plate, and an O-ring is provided in the groove. (See paragraph [0007]) describes a method in which the frame connecting body is subjected to groove processing and an O-ring is sandwiched in the groove.

JP 2008-192506 A JP 2001-319666 A JP 2004-47397 A

  However, in the method described in Patent Document 1, it is difficult to form a frame-like adhesive layer with a uniform thickness on a thin film, and even when bonded, peeling from the conductive layer after bonding is difficult. There was a risk that the oxidant leaked from the adhesive layer. Therefore, further improvement has been desired in terms of ease of manufacture and reliable sealing performance.

  In the method described in Patent Document 2, since the separator and the electrolyte membrane cannot be separated after heat-curing, parts cannot be replaced, and the number of steps such as liquid seal coating and heat-curing increases. In addition, since separator parts are required, there is a problem that the product cannot be thinned.

  The method described in Patent Document 3 requires a frame connector part for grooving. Further, in order to perform grooving, it is necessary to give the frame connector a certain amount of thickness. There was a problem that we couldn't.

  The present invention makes it possible to reduce the labor of assembling work and further reduce the thickness of the product by configuring the sealing material with one independent part and facilitating positioning of the sealing material. It is an object of the present invention to provide a fuel cell and an assembly method thereof.

  In order to solve the above problems, a fuel cell assembling method is configured as follows.

  A fuel electrode and an air electrode are respectively provided on the front and back of the electrolyte membrane to form a membrane electrode assembly. A conductor is formed by providing a conductive layer on a bendable substrate. An air electrode sealing material having a frame-like shape fitted to the outer peripheral portion of the air electrode and having a positioning mechanism positioned with respect to the conductor is formed.

  An air electrode sealing material is attached to the membrane electrode assembly. The conductor is bent substantially at the center, and the membrane electrode assembly is positioned between the conductors by positioning with a positioning member. A membrane electrode assembly including an air electrode sealing material is sandwiched between conductors to form an electromotive body.

  The positioning mechanism is, for example, a protrusion provided on the air electrode sealing material and a notch provided in the bent portion of the conductor, and is formed so that both are positioned when the protrusion is incorporated in the notch. To do.

  In addition, a groove for fitting a protruding piece protruding from the electromotive body is provided in the base for storing the electromotive body, and the electromotive body is stored in the base by aligning the protruding piece with the groove.

  The fuel cell and the assembly method thereof according to the present invention have the following effects.

  A projecting piece as a positioning mechanism is disposed at a predetermined position of the membrane electrode assembly by an air electrode sealing material provided on an outer peripheral portion of the air electrode. By aligning the protruding piece with the notch, the membrane electrode assembly can be reliably disposed at a predetermined position of the bent conductor. By positioning using the positioning mechanism in this manner, the labor involved in the work can be simplified, and the membrane electrode assembly and the conductor can be reliably assembled in a short time.

  Since the membrane electrode assembly and the conductor are engaged with each other by the positioning mechanism, they can be prevented from being displaced and the occurrence of defective products can be reduced.

  By aligning the protruding piece of the electromotive body with the groove portion of the base, the electromotive body can be reliably assembled and stored at a desired position of the base. Further, since the projecting piece is assembled in the groove portion, it is possible to prevent displacement and reduce the occurrence of failure.

It is sectional drawing which shows one Embodiment of the fuel cell concerning this invention. It is a perspective view which shows an example of a conductor. It is a disassembled perspective view which shows an electromotive body. It is a disassembled perspective view which shows the fuel cell of FIG.

  An embodiment of a fuel cell according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 4, the fuel cell 10 includes a base 12, a lid (cover plate) 14, an electromotive body 16, and the like.

  The base 12 is substantially a rectangular parallelepiped, and a storage portion 20 (see FIG. 4) for storing the electromotive body 16 is formed on the upper surface. The base 12 is provided with a fuel supply pipe 18, one of the fuel supply pipes 18 communicates with the storage portion 20, and the other is connected to a fuel tank (not shown) storing fuel. The base 12 is formed with a groove 74 described later.

  The lid 14 is made of a metal plate such as SUS304, and the air holes 15 are formed on almost the entire surface. The lid body 14 is fixed to the upper surface of the base 12 with screws (not shown) or the like. When the lid body 14 is fixed to the base 12, each member stored in the storage portion 20 such as the electromotive body 16. Are brought into close contact with each other.

  The electromotive body 16 is shown in FIG. The electromotive body 16 includes a membrane electrode assembly 22 and a conductor 24 attached to the front and back surfaces of the membrane electrode assembly 22. The membrane electrode assembly 22 includes an electrolyte membrane 26, a fuel electrode (anode catalyst layer) 30, and an air electrode (cathode catalyst layer) 32.

  The electrolyte membrane 26 is, for example, a polyperfluorosulfonic acid-based resin membrane, specifically, a Nafion membrane manufactured by DuPont, a Flemion membrane manufactured by Asahi Glass, or an aciplex membrane manufactured by Asahi Kasei Kogyo Co., Ltd. And is made of a material capable of transporting protons.

  The fuel electrode 30 is provided on the back side of the electrolyte membrane 26 in FIG. 3, and has a laminated structure in which an anode catalyst layer 40 and an anode gas diffusion layer 42 (gas permeable layer) are stacked from the electrolyte membrane 26 side. Yes.

  The anode catalyst layer 40 is made of carbon powder containing a catalyst, for example, and oxidizes the fuel to take out electrons and protons from the fuel. As the anode catalyst, for example, platinum (Pt) fine particles, iron (Fe), nickel (Ni), cobalt (Co), transition metal such as ruthenium (Ru) or molybdenum (Mo), oxides thereof, or the like Fine particles such as alloys of the above are used.

  The anode catalyst is not limited to the above example. Further, a supported catalyst using a conductive support such as a carbon material may be used, or an unsupported catalyst may be used. The anode catalyst layer 40 preferably contains fine particles equivalent to the fine particles of the resin used for the electrolyte membrane 26 from the viewpoint of facilitating proton movement.

  The anode gas diffusion layer 42 is formed of a thin film made of a porous carbon material such as carbon paper or carbon fiber. The anode gas diffusion layer 42 has a diffusion function of uniformly supplying the fuel gas to the anode catalyst layer 40, and also has a current collection function of the anode catalyst layer 40.

  The air electrode 32 is provided on the upper surface side of the electrolyte membrane 26 in FIG. 3, and has a laminated structure in which a cathode catalyst layer 36 and a cathode gas diffusion layer 38 (gas permeable layer) are stacked from the electrolyte membrane 26 side. Yes. The cathode catalyst layer 36 is made of carbon powder containing a catalyst, reduces oxygen, and reacts electrons with protons generated in the anode catalyst layer 40 to generate water.

  The cathode gas diffusion layer 38 is formed of a porous carbon material, and has a diffusion function of uniformly supplying the oxidant to the cathode catalyst layer 36 and also a current collection function of the cathode catalyst layer 36.

  The cathode catalyst layer 36 and the cathode gas diffusion layer 38 have the same configuration as the anode catalyst layer 40 and the anode gas diffusion layer 42 described above, for example. The catalyst used for the cathode catalyst layer 36 and the catalyst for the anode catalyst layer 40 are made of the same material. Protons generated at the fuel electrode 30 are transported to the air electrode 32 via the electrolyte membrane 26.

  The conductor 24 is shown in FIG. As shown in the figure, the conductor 24 includes a substrate 50, a cathode conductive layer 52, an anode conductive layer 54, and the like. The substrate 50 is made of resin, for example, and has appropriate flexibility and electrical insulation. The conductor 24 has a bent portion 25 (indicated by a dotted line) extending in the width direction at the center in the longitudinal direction, and can be bent at the bent portion 25.

  The cathode conductive layer 52 and the anode conductive layer 54 are, for example, porous layers (for example, meshes) made of a metal material such as stainless steel (SUS304, SUS316, etc.), aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, and gold. ) Or a foil body. If a material that does not provide sufficient corrosion resistance is used, it is plated with gold or the like.

  The cathode conductive layer 52 and the anode conductive layer 54 are provided on one surface of the substrate 50 as shown in FIG. The cathode conductive layer 52 and the anode conductive layer 54 are each formed of four strip-shaped electrode portions 53, and the electrode portions 53 are parallel to each other, and when the conductor 24 is bent at the bending portion 25, the anode conductive layer 54 is formed. The electrode part 53 and the electrode part 53 of the cathode conductive layer 52 are arranged so as to face each other vertically.

  Further, an electrode portion 53a positioned at the end portion in the width direction of the cathode conductive layer 52 and an end portion in the width direction of the anode conductive layer 54, and the electrode portion 53b positioned at the end portion opposite to the electrode portion 53a are respectively A terminal 55 is provided. In addition, the electrode portion 53 on which the terminal 55 is not provided is connected by a conductive member 57 to the electrode portion 53 disposed adjacent to one row of the electrode portion 53 facing when the conductor 24 is bent. The conductive member 57 can be bent, and the four series fuel cells 10 are formed between the conductors 24 by arranging the four electrode portions 53 in each conductive layer in this manner. Similarly, the fuel electrode 30 and the air electrode 32 are also divided into four. In addition, the fuel cell 10 is not limited to four rows in series.

  Further, a plurality of fuel supply holes 56 are formed in the anode conductive layer 54, and a plurality of gas flow holes 58 are formed in the cathode conductive layer 52. The fuel supply hole 56 allows fuel gas supplied from a fuel supply mechanism 80 described later to pass therethrough. The fuel gas that has passed through the fuel supply hole 56 is sent into the anode catalyst layer 40 through the anode gas diffusion layer 42.

  The air introduced from the air hole 15 provided in the lid 14 passes through the gas flow hole 58. The air that has passed through the gas flow holes 58 is sent from the cathode gas diffusion layer 38 to the cathode catalyst layer 36 via a moisture retention plate 66 described later. The gas flow hole 58 is formed at a position substantially coincident with the air hole 15 when the lid 14 is fixed to the base 12. Further, a cutout 70 is formed in the conductor 24. The notches 70 are formed by cutting out a part of the conductor 24, and are provided symmetrically on both the left and right sides of the bent portion 25 of the conductor 24 as shown in FIGS.

  As shown in FIG. 3, the air electrode 32 is provided with a sealing material 64 as an air electrode sealing member. The sealing material 64 is made of a rubber-based material having a small amount of fuel permeation and high electrical resistance, such as EPDM (ethylene propylene rubber), fluorine-based rubber, and silicon-based rubber, and has a frame shape suitable for the outer peripheral portion of the air electrode 32. Is formed. Further, the sealing material 64 is provided with a protruding piece 72. The projecting pieces 72 protrude outward from one side of the sealing material 64 and are formed on the left and right sides of one side of the sealing material 64 so as to correspond to the notches 70.

  The membrane electrode assembly 22 to which the sealing material 64 is attached is sandwiched between the conductors 24 folded in two at the bent portion 25 so that the protruding pieces 72 are combined with the notches 70. By sandwiching the membrane electrode assembly 22 with the conductor 24 folded in half, the cathode gas diffusion layer 38 contacts the cathode conductive layer 52 and the anode gas diffusion layer 42 contacts the anode conductive layer 54. The electromotive body 16 is configured by sandwiching a membrane electrode assembly 22 between conductors 24.

  As described above, the storage portion 20 is formed on the base 12 as shown in FIG. The storage unit 20 is formed in substantially the same shape as the outer shape of the electromotive body 16, and the storage unit 20 is provided with the groove portion 74 described above. The groove portion 74 is formed in accordance with the projecting piece 72 protruding from the electromotive body 16, and when the electromotive body 16 is housed in the housing portion 20, the projecting piece 72 is fitted into the groove portion 74.

  A fuel supply mechanism 80 is provided below the base 12. The fuel supply mechanism 80 has a fuel supply pipe 18 connected to an external fuel tank (not shown) and the like, and the upper surface of the fuel supply mechanism 80, that is, the bottom surface of the storage unit 20 is interposed via a bottom plate 86. A gas-liquid separation membrane 84 is provided. The bottom plate 86 is provided with a plurality of vent holes 88 (see FIG. 4). The gas-liquid separation membrane 84 is made of, for example, a polytetrafluoroethylene (PTFE) sheet having a large number of pores, blocks a liquid fuel (methanol liquid or an aqueous solution thereof), and allows only a vaporized component of the fuel to pass through.

  The lid 14 is attached to the base 12 with a moisturizing plate 66 disposed on the upper surface of the electromotive body 16. The moisturizing plate 66 is composed of a porous film having a porosity of 20 to 60%, for example, and prevents dust and foreign matter from entering from the outside and transpiration of water generated in the cathode catalyst layer 36, and cathode gas diffusion. The layer 38 serves as an auxiliary diffusion layer for uniformly introducing an oxidizing agent into the layer 38.

  In each figure, for the sake of illustration, the thickness width of each part is shown enlarged, and the actual thickness width is not shown.

  Next, a method for assembling the fuel cell 10 will be described.

  A sealing material 64 is assembled to the membrane electrode assembly 22. The sealing material 64 is assembled on the electrolyte membrane 26 so as to surround the air electrode 32 in accordance with the outer periphery of the air electrode 32. Thereby, the protruding piece 72 of the sealing material 64 protrudes at one end edge of the membrane electrode assembly 22.

  The conductor 24 is bent in two at the bent portion 25. The membrane electrode assembly 22 is assembled to the conductor 24 while slightly opening the conductor 24 and inserting the protruding piece 72 into the notch 70.

  The conductors 24 are closed and the membrane electrode assembly 22 is sandwiched between the conductors 24. Thereby, the membrane electrode assembly 22 is disposed at a predetermined position of the conductor 24 via the projecting piece 72 of the sealing material 64, the cathode gas diffusion layer 38 comes into contact with the cathode conductive layer 52, and the anode gas diffusion layer 42 is The electromotive body 16 is configured in contact with the anode conductive layer 54.

  When the electromotive body 16 is configured, the electromotive body 16 is housed in the housing portion 20 by aligning the protruding piece 72 protruding from the electromotive body 16 with the groove portion 74. The electromotive body 16 is accommodated in a predetermined position of the base 12 by the groove 74.

  Therefore, according to the fuel cell 10 and its assembly method, the membrane electrode assembly 22 and the conductor 24 are connected to each other by aligning the protrusion 72 with the notch 70 and assembling the membrane electrode assembly 22 to the conductor 24. It is possible to arrange them in a positional relationship, and they can be assembled easily.

  Furthermore, the electromotive member 16 can be stored in a predetermined position of the base 12 easily and surely by aligning the protruding piece 72 with the groove 74 and storing the electromotive member 16 in the base 12. Therefore, it is possible to configure the electromotive body 16 and easily store the electromotive body 16 in the base 12 with little effort. The fuel cell 10 can be reduced in cost by simple assembly, and is less likely to be displaced between members, so that the incidence of defective products can be reduced.

  In the fuel cell 10 of the present invention, the positioning mechanism is not limited to the configuration of the projecting piece 72 and the notch 70. Moreover, you may arrange | position the protrusion 72 etc. asymmetrically. Arranging asymmetrically may be performed by changing not only the mounting position but also the shape and size of the projecting piece. If these are formed in an asymmetrical shape, the front and back surfaces of the membrane electrode assembly 22 can be discriminated from the position of the projecting piece 72. For example, even if the composition is different between the fuel electrode 30 and the air electrode 32, incorrect attachment of the polarity, etc. Can be prevented.

  The present invention can be used for a fuel cell in which a conductor is folded in half.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Base 14 ... Cover body 16 ... Electromotive body 20 ... Storage part 22 ... Membrane electrode assembly 24 ... Conductor 26 ... Electrolyte membrane 30 ... Fuel electrode 32 ... Air electrode 50 ... Substrate 52 ... Cathode conduction Layer 53 ... Electrode portion 54 ... Anode conductive layer 55 ... Terminal 56 ... Fuel supply hole 57 ... Conductive member 58 ... Gas flow hole 64 ... Sealing material 72 ... Projection piece 74 ... Groove portion 80 ... Fuel supply mechanism

Claims (10)

A membrane electrode assembly having a fuel electrode on one surface of the electrolyte membrane and an air electrode on the other surface;
A conductor having a fuel electrode conductor connected to the fuel electrode and an air electrode conductor connected to the air electrode on a foldable substrate;
In the fuel cell in which the membrane electrode assembly is assembled to the conductor bent at the bent portion to constitute an electromotive body, and fuel and oxidant are supplied to the electromotive body to generate electric power.
On the outer periphery of the air electrode, an air electrode sealing material that seals between the electrolyte membrane and the air electrode conductor is placed,
Assembling the electromotive body by assembling the first positioning portion formed on the conductor and the second positioning portion provided on the air electrode sealing material, and combining the membrane electrode assembly with the conductor. A fuel cell assembling method characterized by the above.   The first positioning part is a notch formed in a bent part of the conductor, and the second positioning part is a projecting piece formed in the air electrode sealing material. Item 4. A fuel cell assembling method according to Item 1.   The fuel according to claim 1 or 2, wherein the first positioning portion protruding from the electromotive member is combined with a groove portion formed in advance on the base, and the electromotive member is accommodated in the base. Battery assembly method.   4. The fuel according to claim 2, wherein the first positioning portion is formed at both ends of the bent portion, and the second positioning portion is formed according to the first positioning portion. Battery assembly method.   4. The fuel cell according to claim 1, wherein at least one of the first positioning portion and the second positioning portion is formed asymmetrically with respect to the electromotive body. 5. Assembly method. A membrane electrode assembly having a fuel electrode on one surface of the electrolyte membrane and an air electrode on the other surface;
A conductor having a fuel electrode conductor connected to the fuel electrode and an air electrode conductor connected to the air electrode on a foldable substrate;
An air electrode sealing material that is attached to the outer periphery of the air electrode and seals between the electrolyte membrane and the air electrode conductor;
In the fuel cell in which the membrane electrode assembly is assembled to the conductor bent at the bent portion to constitute an electromotive body, and fuel and oxidant are supplied to the electromotive body to generate electric power.
A fuel cell characterized in that a positioning portion is provided on at least one of the air sealing material and the conductor, and the air sealing material and the conductor can be assembled in a predetermined positional relationship by the positioning portion. .   The positioning portion includes a notch formed in the bent portion of the conductor, and a projecting piece provided in the air electrode sealing material and configured to be assembled to the notch. The fuel cell according to claim 6. A groove is formed in the base for housing the electromotive member so as to match the positioning portion protruding from the electromotive member,
8. The fuel cell according to claim 6, wherein the electromotive body is housed in a base by combining the positioning portion with the groove portion.   9. The fuel cell according to claim 7, wherein the positioning portion is provided symmetrically with respect to the conductor.   The fuel cell according to claim 7 or 8, wherein the positioning portion is provided asymmetrically with respect to the conductor.

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