JP2007134163A - Polymer electrolyte fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer electrolyte fuel cell capable of reducing mechanical damage to a polymer electrolyte membrane by keeping pressure applied on gas diffusion electrode surfaces uniform by keeping a regular distance between parts outside the gas diffusion electrodes and separators and a regular distance between a part of the polymer electrolyte membrane where the gas diffusion electrodes are formed and the separators. <P>SOLUTION: The polymer electrolyte fuel cell includes: an MEA 9 having the polymer electrolyte membrane 3 and the pair of gas diffusion electrodes 8 sandwiching the polymer electrolyte membrane 3; a pair of gaskets arranged on the MEA 9; and a pair of conductive separators 4 which are arranged to sandwich the MEA 9 and the gaskets 7 and in each of which a groove-like gas passage 5 or a gas passage 6 for running a reaction gas is formed on the inside surface thereof. In this polymer electrolyte fuel cell, one or more pairs of spacers 100a and 100b are arranged in each gas diffusion electrode 8 and each gasket 7 to contact the separator 4 and to sandwich the polymer electrolyte membrane 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a structure of a fuel cell, particularly a polymer electrolyte fuel cell, used in a power source for portable devices, a power source for electric vehicles, a domestic cogeneration system, and the like.

  A polymer electrolyte fuel cell generates electricity and heat simultaneously by reforming a source gas such as city gas and electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. It is something to be made. A unit cell (cell) of this fuel cell has an electrolyte membrane electrode assembly (MEA) composed of a polymer electrolyte membrane and a pair of gas diffusion electrodes, a gasket, and a conductive separator. The MEA having a gasket disposed at the peripheral edge is sandwiched between a pair of separators to form a cell.

  In such a polymer electrolyte fuel cell, it is common to increase the cell electrode area so that the output current is proportional to the size of the electrode area and to reduce the manufacturing cost. Since the voltage obtained from the above is low, the cells are stacked and fastened, and the adjacent MEAs are electrically connected in series to obtain the required output voltage. Since the fuel cell generates heat during operation, it is necessary to cool it with cooling water or the like in order to maintain the battery in a good temperature state. Usually, a cooling channel for flowing cooling water is provided for every 1 to 3 cells. It has been.

  For this reason, in a fuel cell in which the entire battery (more precisely, a cell stack) is fastened, the polymer electrolyte membrane, gas diffusion electrode, etc. constituting the MEA are subjected to pressure over time when operated for a long period of time. As a result, creep occurs, causing mechanical damage to the polymer electrolyte membrane. As a result, there has been a problem that the life of the fuel cell is remarkably shortened by the occurrence of cross leaks of the fuel gas and the oxidant gas.

As a means for reducing damage to the polymer electrolyte membrane due to creep of the members constituting the fuel cell, a fuel cell is known in which an interval holding means is provided on the outer periphery of the gas diffusion electrode at the peripheral portion of the MEA. (See, for example, Patent Document 1). In addition, it is known that creep is prevented by making a region sandwiched in the cell stacking direction of the gasket into a fixed size structure (see, for example, Patent Document 2). In these, the pressure between the polymer electrolyte membrane and the separator is made constant around the gas diffusion electrode, thereby making the pressure applied in the cell constant and preventing excessive creep.
JP-A-6-333582 JP 2004-165125 A

However, the above-described interval holding means of Patent Document 1 and the fixed-size structure of Patent Document 2 are provided on the peripheral edge of the MEA so as to be located outside the gas diffusion electrode. For this reason, especially when a metal separator having low rigidity is used or when the area of the gas diffusion electrode is increased, the distance between the portion of the polymer electrolyte membrane where the gas diffusion electrode is formed and the separator (gas There was a problem that the thickness of the diffusion electrode) could not be kept constant and excessive creep occurred.
The present invention has been made to solve such a problem, and the gap between the outer portion of the gas diffusion electrode of the polymer electrolyte membrane and the separator and the gas diffusion electrode of the polymer electrolyte membrane are formed. To provide a polymer electrolyte fuel cell capable of maintaining a uniform pressure in the cell and reducing mechanical damage to the polymer electrolyte membrane by making the distance between the portion and the separator constant. Objective.

  In order to solve such a problem, a polymer electrolyte fuel cell of the present invention includes a polymer electrolyte membrane and an MEA having a pair of gas diffusion electrodes that sandwich an inner portion from the peripheral edge of the polymer electrolyte membrane, A pair of gaskets disposed at the peripheral edge portions of both surfaces of the MEA so as to surround the gas diffusion electrode, and a groove-shaped gas flow path disposed so as to sandwich the MEA and the gasket and in which a reaction gas flows on the inner surface And a cell stack in which the cells are stacked, and one or more pairs of spacers are provided inside the gas diffusion electrode and the gasket, respectively. It is disposed so as to be in contact with the pair of separators in the stacking direction and sandwich the polymer electrolyte membrane.

  With this configuration, not only the periphery of the gas diffusion electrode but also the distance in the electrode is kept constant, so that the pressure applied in the cell can be kept uniform and mechanical damage to the polymer electrolyte membrane can be reduced. .

  The groove-like gas flow path is formed so as to have a plurality of parallel running portions, and the spacer disposed inside the gas diffusion electrode is arranged so as to be in contact with the parallel running portions of the gas flow paths. It is preferable to be provided.

  Each of the pair of gas diffusion electrodes and the pair of gaskets is provided with a through hole in the cell stacking direction, the spacer is disposed in the through hole, and the pair of separators are portions corresponding to the through holes. Preferably, the spacer has a protrusion, and the spacer is in contact with the protrusion.

  The spacer preferably has electrical insulation.

  The Young's modulus of the spacer is preferably higher than the Young's modulus of the gasket.

  According to the polymer electrolyte fuel cell of the present invention, by preventing mechanical damage to the polymer electrolyte membrane due to creep generated in the cell during operation of the fuel cell, it is possible to generate power stably with a longer life compared to the conventional case. It becomes possible to do.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram showing an outline of a polymer electrolyte fuel cell according to Embodiment 1 of the present invention. FIG. 2 is a cross-sectional view schematically showing the structure of the polymer electrolyte fuel cell according to Embodiment 1 of the present invention. In FIG. 2, for convenience of explanation, a part of the laminated structure of the polymer electrolyte battery (unit cell) is shown.

  First, the configuration of a polymer electrolyte fuel cell according to the present embodiment (hereinafter simply referred to as a fuel cell) will be described with reference to FIG.

  As shown in FIG. 1, the polymer electrolyte fuel cell according to the present embodiment has a cell stack 31. The cell stack 31 includes a cell stack 41 in which cells 24 having a plate-like overall shape are stacked in the thickness direction, and first and second end plates 21 a and 21 b disposed at both ends of the cell stack 41. And a fastener (not shown) that fastens the cell stack 41 and the first and second end plates 21 a and 21 b in the stacking direction of the cells 24. The first and second end plates 21a and 21b are provided with current collecting terminals, but are not shown.

  A fuel gas supply manifold 11 is formed in the upper part of one side portion of the cell stack 41 so as to penetrate in the stacking direction of the cell stack 41. One end of the fuel gas supply manifold 11 communicates with a through hole formed in the first end plate 21a, and a fuel gas supply pipe 22 is connected to the through hole. The other end of the fuel gas supply manifold 11 is closed by a second end plate 21b. A fuel gas discharge manifold 12 is formed in the lower part of the other side portion of the cell stack 41 so as to penetrate in the stacking direction of the cell stack 41. One end of the fuel gas discharge manifold 12 communicates with a through hole formed in the second end plate 21b, and a fuel gas discharge pipe 23 is connected to the through hole. The other end of the fuel gas supply manifold 12 is closed by a first end plate 21a.

  Similarly, an oxidant gas supply manifold and a cooling water supply manifold (not shown) are formed on the upper portion of one side of the cell stack 41 so as to penetrate in the stacking direction of the cell stack 41. One end of each of the oxidant gas supply manifold and the cooling water supply manifold communicates with a through hole (not shown) formed in the first end plate 21a. The oxidant gas supply pipe and the cooling water (not shown) are connected to the through hole. Each supply pipe is connected. The other ends of the oxidant gas supply manifold and the cooling water supply manifold are closed by a second end plate 21b. In addition, an oxidant gas discharge manifold and a cooling water discharge manifold (not shown) are formed in the lower part of the other side portion of the cell stack 41 so as to penetrate in the stacking direction of the cell stack 41. One end of each of the oxidant gas discharge manifold and the coolant discharge manifold communicates with a through hole (not shown) formed in the second end plate 21b, and the oxidant gas discharge pipe and cooling water (not shown) are connected to the through hole. Each discharge pipe is connected. The other ends of the oxidant gas discharge manifold and the cooling water discharge manifold are closed by a first end plate 21a.

  As shown in FIG. 2, the cell 24 includes an MEA (electrolyte membrane electrode assembly) 9, a gasket 7, and a separator 4.

  The MEA 9 includes a polymer electrolyte membrane 3 that selectively transports hydrogen ions and a gas diffusion electrode 8. A pair of gas diffusion electrodes 8 are provided on both surfaces of the polymer electrolyte membrane so as to be located inward from the peripheral edge thereof. The gas diffusion electrode 8 is provided on the main surface of the polymer electrolyte membrane 3, and has a catalytic reaction layer (anode catalyst layer 2a and cathode catalyst layer 2b) 2 mainly composed of carbon powder carrying a platinum-based metal catalyst. The gas diffusion layer 1 is provided on the catalytic reaction layer 2 and has both gas permeability and conductivity. A pair of gaskets 7 is disposed around the gas diffusion electrode 8 with the polymer electrolyte membrane 3 interposed therebetween. This prevents fuel gas and oxidant gas from leaking out of the battery, and prevents these gases from being mixed with each other.

  A pair of conductive separators 4 (anode separator 4a and cathode separator 4b) are disposed so as to sandwich the MEA 9 and the gasket 7. The material of the separator 4 may be made of carbon or metal. The separator 4 mechanically fixes the MEA 9 and adjacent MEAs are electrically connected to each other in series.

  A gas flow path 5 for flowing fuel gas is provided on the inner surface of the anode separator 4a (the surface in contact with the MEA 9). Further, a fuel gas supply manifold hole 11a and a fuel gas discharge manifold hole 12a each including a through hole in the thickness direction are provided at the peripheral edge of the separator 4a (see FIG. 3). The gas flow path 5 is formed in a groove shape, and is disposed so as to connect between the fuel gas supply manifold hole 11a and the fuel gas discharge manifold 12a hole.

  On the other hand, on the inner surface of the cathode separator 4b, a gas flow path 6 for flowing an oxidant gas is provided, and a manifold hole (not shown) for supplying and discharging the oxidant gas is provided. The gas flow path 6 is formed in a groove shape, and is disposed so as to connect these manifold holes.

  Further, on the outer surface of the separator 4, a cooling flow path 13 for flowing cooling water is formed in a groove shape, and a manifold hole (not shown) for supplying and discharging cooling water is provided. The cooling flow path 13 is provided in a groove shape so as to connect these manifold holes.

  The gasket 7 is provided with a fuel gas supply manifold hole 11 b and a fuel gas discharge manifold hole 12 b so as to correspond to the fuel gas supply manifold hole 11 a and the fuel gas discharge manifold hole 12 a provided in the separator 4. (See FIG. 4). An oxidant gas supply manifold hole, an oxidant gas discharge manifold hole, a cooling water supply manifold hole, and a cooling water discharge manifold hole are respectively provided (not shown).

  The polymer electrolyte membrane 3 has a fuel gas supply manifold hole 11c and a fuel gas discharge manifold hole so as to correspond to the fuel gas supply manifold hole 11a and the fuel gas discharge manifold hole 12a provided in the separator 4. 12c is provided (see FIG. 5). An oxidant gas supply manifold hole, an oxidant gas discharge manifold hole, a cooling water supply manifold hole, and a cooling water discharge manifold hole are respectively provided (not shown).

  The cell stack 41 is formed by stacking the cells 24 thus formed in the thickness direction. The fuel gas supply manifold holes 11a, 11b, 11c and the fuel gas discharge manifold holes 12a, 12b, 12c provided in the separator 4, the gasket 7 and the polymer electrolyte membrane 3 are arranged in the thickness direction when the cells 24 are stacked. In this way, a fuel gas supply manifold 11 and a fuel gas discharge manifold 12 are formed. Similarly, an oxidant gas supply manifold, an oxidant gas discharge manifold, a coolant supply manifold, and a coolant discharge manifold (not shown) are formed.

  As a result, fuel gas is distributed and supplied from the fuel gas supply manifold 11 to the gas flow path 5, and unused fuel gas is discharged from the fuel gas discharge manifold 12. Similarly, oxidant gas is supplied from the oxidant gas supply manifold to the gas flow path 6 and discharged from the oxidant gas discharge manifold. Further, the cooling water is supplied from the cooling water supply manifold to the cooling flow path and is discharged from the cooling water discharge manifold.

Next, a characteristic configuration of the present invention will be described with reference to FIGS.
FIG. 3 is a schematic diagram showing the configuration of the separator and spacer of the cell shown in FIG. FIG. 4 is a schematic diagram showing the configuration of the gasket of the cell shown in FIG. FIG. 5 is a schematic diagram showing the configuration of the MEA of the cell shown in FIG.

  As shown in FIG. 3, a gas flow path 5 formed in a groove shape is formed in a serpentine shape on the inner surface of the anode separator 4a. Similarly, a gas flow path 6 formed in a groove shape is formed in a serpentine shape on the inner surface of the cathode separator 4b. Accordingly, the horizontally formed portions run in parallel with each other. The gas flow path 5 and the gas flow path 6 are not limited to the serpentine shape, and may be configured to form a plurality of branch flow paths between one main flow path and the other main flow path of the gas flow path. It is good also as a structure which a some flow path runs mutually in parallel.

  On the inner surface of the separator 4, a portion between the groove-like gas channel formed in a serpentine shape and the gas channel, that is, a convex portion called a rib portion 10 (a parallel running portion of the gas channel), One spacer 100a is provided at a plurality of locations (here, 4 locations). With such a configuration, the flow of the reaction gas or the unused reaction gas flowing in the gas flow path 5 or the gas flow path 6 is not hindered, so that the fuel cell can be stably operated for a long time. .

From the viewpoint of sufficiently obtaining the effects of the present invention, it is preferable that 1 to 10 first spacers 100a are provided for the gas diffusion electrode 8 of 100 to 400 cm ² , and the pressure applied to the cells is reliably uniform. It is more preferable to provide 4 or more from the viewpoint of making it more preferable, and it is more preferable to provide 6 or less from the viewpoint of facilitating the manufacturing process.

  Further, the first spacers 100a are provided so as to have an appropriate interval (here, equal intervals).

  Although the shape of the first spacer 100a is formed in a columnar shape (here, a quadrangular columnar shape), the cross-sectional shape is not particularly limited.

  On the other hand, the gas diffusion electrode 8 of the MEA 9 is provided with a first spacer accommodating hole 101a (through hole) at a position corresponding to the first spacer 100a (see FIG. 5). The first spacer accommodating hole 101a is formed so as to penetrate the gas diffusion electrode 8 in the thickness direction. Further, the first spacer receiving hole 101a is formed so as to be fitted just with the first spacer 100a. The first spacer receiving hole 101a is preferably sized so that there is no gap between the first spacer receiving hole 101a and the first spacer 100a when the fuel cell is fastened.

  Moreover, the 2nd spacer 100b is provided in multiple places (here 8 places) so that the peripheral part of the anode separator 4a may surround the serpentine-like gas flow path 5 whole (refer FIG. 3). Similarly, the second spacer 100b is provided at a plurality of locations (here, 8 locations) so as to surround the entire serpentine gas flow path 6 at the peripheral portion of the cathode separator 4b. Here, the installation location of the second spacer 100b is provided so as to surround the entire serpentine gas flow path 5 or the gas flow path 6. However, the present invention is not limited to this, and the polymer electrolyte membrane 3 is not limited to this. As long as the gap between the pair of separators 4 facing each other is constant, the installation location may be arranged at any position. Further, the number of the second spacers 100b to be installed is not particularly limited as long as the distance between the pair of separators 4 facing each other with the polymer electrolyte membrane 3 interposed therebetween is constant. The shape of the second spacer 100b is formed in a columnar shape (here, a quadrangular columnar shape) similarly to the shape of the first spacer 100a, but the cross-sectional shape is not particularly limited.

  On the other hand, the gasket 7 is provided with a second spacer accommodating hole 101b (through hole) at a position corresponding to the second spacer 100b (see FIG. 4). The second spacer accommodating hole 101b is formed so as to penetrate the gasket 7 in the thickness direction. The second spacer receiving hole 101b is formed so as to be fitted to the second spacer 100b. The second spacer receiving hole 101b may have a gap between the second spacer 100b and the second spacer 100b when the fuel cell is fastened.

  Moreover, it is preferable that the heights of the first spacer 100a and the second spacer 100b are equal.

  In the fuel cell assembled to the cell stack 31 and fastened with a fastener, as shown in FIG. 2, a first spacer 100a and a second spacer 100b are provided so as to sandwich the polymer electrolyte membrane 3, respectively. The thickness of the gas diffusion electrode 8 is compressed to the height h1 of the first spacer 100a and the second spacer 100b. The height h1 of the spacer is preferably set in consideration of the degree to which the gas diffusion electrode 8 and the gasket 7 are compressed.

  As shown in FIG. 2, the portions of the first spacer 100a and the second spacer 100b that are in contact with the polymer electrolyte membrane 3 are cut off at the corners of the contact surfaces when the shape of the spacer is a rectangular parallelepiped, for example. Is preferred. This makes it possible to fasten the polymer electrolyte membrane without damaging it.

  The material of the first spacer 100a and the second spacer 100b ensures the risk of a short circuit due to the proximity of the first spacer (or the second spacer) facing each other across the polymer electrolyte membrane 3. From the standpoint of preventing this, it is preferable to have electrical insulation. Examples of those having electrical insulation include polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyether ketone, and polyethylene naphthalene.

  The Young's modulus of the material of the first spacer 100a and the second spacer 100b is preferably higher than that of the gasket 7 in order to sufficiently function as a spacer. For example, since the Young's modulus of a rubber material such as fluororubber used for the gasket 7 is about 10 MPa, if the Young's modulus of the material of the first spacer 100a and the second spacer 100b is more than that, Good.

  When the materials of the first spacer 100a and the second spacer 100b are in the relationship of the Young's modulus as described above, the first spacer 100a and the second spacer are further used from the viewpoint of sufficiently performing the function of the spacer of the present invention. The material 100b preferably has a coefficient of thermal expansion greater than that of the gasket material.

  Note that the MEA 9 in the fuel cell of the present invention has a portion (the first spacer accommodating hole 101a) made only of the polymer electrolyte membrane 3 in a portion where the first spacer 100a in the gas diffusion electrode 8 is installed. The electrode is not electrically divided but functions as one electrode.

By adopting such a configuration, the distance between the separator and the polymer electrolyte membrane can be kept constant not only in the periphery of the gas diffusion electrode but also in the electrode, so that the fastening pressure in the cell is made uniform and high. Mechanical damage to the molecular electrolyte membrane can be reduced.
(Embodiment 2)
FIG. 6 is a cross-sectional view schematically showing the structure of the polymer electrolyte fuel cell according to Embodiment 2 of the present invention. In FIG. 6, as in FIG. 2 (Embodiment 1), for convenience of explanation, a part (unit cell) of the laminated structure of the polymer electrolyte battery is shown. In FIG. 6, the same reference numerals are given to the same components as those of the fuel cell according to the first embodiment described above, and the basic configuration is the same as that of the first embodiment. .

  As shown in FIG. 6, the separator 14 is formed with a first spacer installation portion 201a (protruding portion) at a portion where the first spacer 100a shown in the first embodiment is disposed. A first spacer 200a is disposed at the tip of the first spacer installation portion 201a. The first spacer installation portion 201a has the same cross-sectional shape as the first spacer 200a and has a predetermined height h4, and is formed in a column shape integrally with the first spacer 200a.

  The height h2 of the gas diffusion electrode 8 is compressed to the height h4 of the first spacer installation portion 201a and the height h3 of the first spacer 200a after the cell stack is fastened.

  Further, a second spacer installation portion 201b (protruding portion) is formed on the peripheral portion of the separator 14 at a portion where the second spacer 100b shown in the first embodiment is disposed. A second spacer 200b is disposed at the tip of the second spacer installation portion 201b. The installation location of the second spacer installation portion 201b is provided so as to surround the gas flow path 5 or the gas flow path 6 here, but is not limited to this, and sandwiches the polymer electrolyte membrane 3 therebetween. As long as the distance between the pair of separators facing each other is constant, the installation location may be arranged at any position, and the number of installation is not particularly limited. The second spacer installation portion 201b has the same cross-sectional shape as the second spacer 200b, is provided to have a predetermined height h6, and is formed in a columnar shape integrally with the second spacer 200b.

  The height h2 of the gas diffusion electrode 8 is compressed to the height h6 of the second spacer installation portion 201b and the height h5 of the second spacer 200b after the cell stack is fastened.

  It is preferable that the height h4 of the first spacer installation portion 201a is equal to the height h6 of the second spacer installation portion 201b.

  The height h4 of the first spacer installation portion 201a and the height h6 of the second spacer installation portion 201b may be smaller than the height h2 of the gas diffusion electrode 8 after the cell stack is fastened. In view of the above, it is preferably larger than 0%, and is preferably 80% or less of the height h2 of the gas diffusion electrode 8 in order to sufficiently maintain the strength of the spacer and to reliably exert its function.

  Since the spacer material and the like are the same as those in the first embodiment, detailed description thereof is omitted.

  Further, when producing such a fuel cell, the assembly is simplified if the first spacer 200a is bonded to the MEA 9 in advance.

  By configuring as described above, the gap between the separator and the polymer electrolyte membrane can be kept constant not only in the periphery of the gas diffusion electrode but also in the electrode, so that the fastening pressure in the cell is made uniform, It is possible to reduce mechanical damage to the polymer electrolyte membrane.

  Hereinafter, examples of the present invention will be described together with an example of a method for manufacturing a fuel cell according to an embodiment.

Example 1
In this example, the polymer electrolyte fuel cell described in Embodiment 1 was produced by the following process.

  First, formation of the MEA 9 will be described.

  The polymer electrolyte membrane 3 (NAFION 112 manufactured by DuPont, USA) was provided with manifold holes such as a fuel gas supply manifold hole 11c and a fuel gas discharge manifold hole 12c.

An appropriate amount of platinum particles as a catalyst was supported on carbon particles and made into a paste by a well-known method. Using this carbon particle paste containing platinum particles, printing was performed on both surfaces of the polymer electrolyte membrane 3 so as to have an area of 400 cm ² and a thickness of 20 μm by screen printing, thereby forming the catalyst reaction layer 2. At this time, as shown in FIG. 5, four square holes each having a side of 2 mm are provided at positions corresponding to the parallel running portions (rib portions 10) between the groove-like gas flow paths. Provided. The holes were formed by printing with patterning so as not to paint the paste.

  The position corresponding to the hole of the carbon nonwoven fabric to be the gas diffusion layer 1 was removed by a known method (for example, press working). The carbon nonwoven fabric from which the pores were removed was joined by hot pressing so as to be in contact with the catalytic reaction layer 2 printed on the polymer electrolyte membrane 3, thereby producing MEA9. At this time, the thickness of the formed gas diffusion electrode 8 was 250 μm. The first spacer accommodating hole 101 a was formed from the hole provided in the catalyst reaction layer 2 and the hole provided in the gas diffusion layer 1.

  The paste is printed on the carbon nonwoven fabric to be the gas diffusion layer 1 by a screen printing method to produce the gas diffusion electrode 8, and the portion where the first spacer accommodating hole 101a is disposed is formed by a known method. After the removal, the gas diffusion electrode 8 may be joined to the polymer electrolyte membrane 3 by hot pressing to produce the MEA 9.

  The fluororubber sheet is punched out through the second spacer housing portion 101b into which the second spacer 100b is fitted with manifold holes such as the fuel gas supply manifold hole 11b and the fuel gas discharge manifold hole 12b shown in FIG. A gasket 7 was produced. The second spacer accommodating portions 101 b are arranged at equal intervals so as to surround the gas flow path 5 or the gas flow path 6 at the peripheral edge of the gasket 7.

  The gasket 7 was disposed on the peripheral edge of the polymer electrolyte membrane 3 exposed on the outer periphery of the gas diffusion electrode 5 or the gas flow path 6 and joined and integrated by hot pressing.

  Separator 4 forms manifold holes, such as gas flow path 5 or gas flow path 6, fuel gas supply manifold hole 11a, and fuel gas discharge manifold hole 12a, by machining on an isotropic graphite plate having a thickness of 3 mm. (See FIGS. 2 and 3). The gas channel has a groove width of 2 mm, a depth of 1 mm, and a width between the channels of 2 mm. The cooling channel 13 is the same as the gas channel except for the groove width of 1 mm.

  The first spacer 100a and the second spacer 100b are made of polyethylene naphthalene having a Young's modulus of about 18 GPa so as to have a square shape of 2 mm square and a height of 200 μm. The polymer electrolyte membrane 3 The corner of the surface that comes into contact with the surface has been rounded off. The first spacer 100a and the second spacer 100b thus produced were bonded to the inner surface of the separator 4 at positions corresponding to the first spacer accommodating portion and the second spacer accommodating portion, respectively.

  The cell 24 was formed by sandwiching the MEA 9 and the gasket 7 between the pair of separators 4. The cell 24 was laminated | stacked, the cell laminated body 41 was formed, the load was applied using the fastener, and it fastened, and the cell stack 31 was formed. The thickness of the gas diffusion electrode 8 of the cell 24 after fastening was compressed to the height h1 (200 μm) of the spacer.

Since the fuel cell of this example produced in this way can keep the distance between the separator and the polymer electrolyte membrane constant not only in the vicinity of the gas diffusion electrode but also in the electrode, the fastening pressure in the cell is It becomes uniform, and it becomes possible to reduce mechanical damage to the polymer electrolyte membrane.
(Example 2)
In this example, the polymer electrolyte fuel cell described in the second embodiment was manufactured.
This embodiment has the same basic aspect as that of the first embodiment, but the spacer and the separator are different in the following points.

  The first spacer 200a and the second spacer 200b were made of the same material as in Example 1. The shape of these spacers was a 2 mm square shape with a thickness of 50 μm, and was prepared so as to round off the corners of the surface in contact with the polymer electrolyte membrane.

  As in the first embodiment, the separator 14 is formed with the gas flow path 5 or the gas flow path 6, the manifold hole, and the like on the isotropic graphite plate by machining, but the first spacer installation portion 201 a and the second spacer are formed. The separator 14 was formed so that the installation part 201b was 150 μm thicker in the thickness direction than the other part where the spacer was not provided. That is, the first separator installation portion 201 a was formed in a column shape so as to protrude from the inner surface of the separator 14 by 150 μm. Similarly, the second separator installation portion 201b was formed in a column shape so as to protrude from the inner surface of the separator 14 by 150 μm.

  In the fuel cell of this embodiment, the gas diffusion electrode is the sum of the thicknesses of the first spacer installation part 201a and the first spacer 200a (or the second spacer installation part 201b and the second spacer 200b) at the time of fastening. Compressed to 200 μm.

  In this embodiment, if the first spacer 200a is bonded in advance to the MEA 9, the cell can be easily manufactured.

  The fuel cell of this example produced in this way maintains a constant distance between the separator and the polymer electrolyte membrane not only in the vicinity of the gas diffusion electrode but also in the electrode, as in the fuel cell of Example 1. Therefore, the fastening pressure in the cell is made uniform, and mechanical damage to the polymer electrolyte membrane can be reduced.

  The polymer electrolyte fuel cell according to the present invention is useful as a fuel cell used for a power source for portable devices, a power source for electric vehicles, a domestic cogeneration system, and the like.

1 is a schematic diagram showing an outline of a polymer electrolyte fuel cell according to Embodiment 1 of the present invention. 1 is a cross-sectional view schematically showing a configuration of a polymer electrolyte fuel cell according to Embodiment 1 of the present invention. It is a schematic diagram which shows the structure of the separator and spacer of the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the structure of the gasket of the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the structure of MEA of the polymer electrolyte fuel cell which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the outline of a structure of the polymer electrolyte fuel cell which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas diffusion layer 2 Catalytic reaction layer 2a Anode catalyst layer 2b Cathode catalyst layer 3 Polymer electrolyte membrane 4 Separator 4a Anode separator 4b Cathode separator 5 Gas flow path 6 Gas flow path 7 Gasket 8 Gas diffusion electrode 9 MEA
DESCRIPTION OF SYMBOLS 10 Rib part 11 Fuel gas supply manifold 11a Fuel gas supply manifold hole 11b Fuel gas supply manifold hole 11c Fuel gas supply manifold hole 12 Fuel gas discharge manifold 12a Fuel gas discharge manifold hole 12b Fuel gas discharge manifold hole 12c Fuel gas discharge manifold hole 13 Cooling flow path 21a End plate 21b End plate 22 Fuel gas supply pipe 23 Fuel gas discharge pipe 24 Cell 31 Cell stack 41 Cell stack 100a First spacer 100b Second spacer 101a Second spacer 101a 1 spacer accommodation hole 101b 2nd spacer accommodation hole 200a 1st spacer 200b 2nd spacer 201a 1st spacer installation part 201b 2nd spacer installation part

Claims (5)

An MEA having a polymer electrolyte membrane and a pair of gas diffusion electrodes sandwiching the inner part from the periphery of the polymer electrolyte membrane, and disposed on the periphery of both sides of the MEA so as to surround the gas diffusion electrode A cell having a pair of gaskets and a pair of conductive separators disposed so as to sandwich the MEA and the gasket and having a groove-like gas flow path on the inner surface through which a reaction gas flows, and the cells stacked Cell stack,
One or more pairs of spacers are disposed inside the gas diffusion electrode and the gasket, respectively, so as to contact the pair of separators in the cell stacking direction and sandwich the polymer electrolyte membrane. Electrolytic fuel cell.   The groove-like gas flow path is formed so as to have a plurality of parallel running portions, and the spacer disposed inside the gas diffusion electrode is arranged so as to be in contact with the parallel running portions of the gas flow paths. The polymer electrolyte mold battery according to claim 1, which is provided.   Each of the pair of gas diffusion electrodes and the pair of gaskets is provided with a through hole in the cell stacking direction, the spacer is disposed in the through hole, and the pair of separators are portions corresponding to the through holes. The polymer electrolyte fuel cell according to claim 1, wherein the spacer has a protrusion, and the spacer is in contact with the protrusion. The polymer electrolyte fuel cell according to claim 1, wherein the spacer has electrical insulation.   The polymer electrolyte fuel cell according to claim 1, wherein a Young's modulus of the spacer is higher than a Young's modulus of the gasket.

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