JP2015215957A - Fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of arranging an adhesive in a prescribed position of an outer periphery of a membrane electrode assembly in just proportion.SOLUTION: A fuel cell 100 comprises a membrane electrode assembly 20, a first gas diffusion layer 31 and a second gas diffusion layer 32, a frame-like member 40, an adhesion part 50, and a separator 60. The membrane electrode assembly 20 includes an extension region ER extending to the outside of the first gas diffusion layer 31. The frame-like member 40 is arranged on the extension region ER, and includes an inner peripheral part 42 which is an adhesion site in contact with the adhesion part 50. The adhesion part 50 covers the region between an outer peripheral end of the first gas diffusion layer 31 and the inner peripheral part 42 of the frame-like member 40, and includes an elevation 51 locally raised more than a surface of the first gas diffusion layer 31. The separator 60 includes a passage groove 61 formed so as to be able to accommodate the elevation 51.

Description

  The present invention relates to a fuel cell.

  A polymer electrolyte fuel cell (hereinafter also simply referred to as “fuel cell”) includes a membrane electrode assembly in which electrodes are arranged on both surfaces of an electrolyte membrane. The membrane electrode assembly is sandwiched between two plate-like members called separators to constitute a power generator (hereinafter also referred to as “single cell”). In general, in a single cell, a member for holding a membrane electrode assembly and sealing its power generation region and a member for constituting a gas flow path are arranged on the outer periphery of the membrane electrode assembly (Patent Document). 1-5 etc.). These members may be composed of an adhesive or may be adhered to the membrane electrode assembly through the adhesive (Patent Documents 2-5).

JP 2013-89517 A JP 2007-087763 A JP 2005-216802 A JP 2006-156176 A JP 11-31528 A

  A fuel cell usually has a stack structure in which a plurality of single cells are stacked and fastened. In each single cell of the fuel cell, the membrane electrode assembly is always subjected to a surface pressure and is held in a stressed state. Has been. When the adhesive is disposed on the outer periphery of the membrane electrode assembly as in Patent Document 2-5, an extra adhesive is fixed to a part other than a predetermined part due to a manufacturing error, and the adhesive is fixed. There is a possibility that the stress generated in the membrane electrode assembly is increased. In addition, if the adhesive to be disposed on the outer periphery of the membrane electrode assembly is insufficient, there is a possibility that problems such as a decrease in the protection of the end of the electrolyte membrane and the airtightness of the power generation region may occur. It was. As described above, in the fuel cell, there is still room for improvement with respect to arranging the adhesive at a predetermined position on the outer periphery of the membrane electrode assembly without excess or deficiency. In addition, in the fuel cell, it is desired to reduce the size, reduce the cost, save resources, facilitate the production, improve the production efficiency, and the like.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms.

[1] According to one aspect of the present invention, a fuel cell is provided. The fuel cell may include a membrane electrode assembly, a gas diffusion layer, an outer peripheral member, an adhesive portion, and a separator. The membrane electrode assembly may have a configuration in which electrodes are arranged on both surfaces of the electrolyte membrane. The gas diffusion layer may be disposed on at least one electrode of the membrane electrode assembly. The outer peripheral member may be disposed on an outer peripheral edge portion of the membrane electrode assembly. The adhesive member may be provided with an adhesive member that adheres the outer peripheral member and the outer peripheral edge of the membrane electrode assembly. The separator may be disposed so as to face the gas diffusion layer. The outer peripheral edge of the membrane electrode assembly is located on the outer side of the gas diffusion layer because the outer peripheral contour of the gas diffusion layer is located inside the outer peripheral contour of the electrolyte membrane of the membrane electrode assembly. It may have an extended region extending to the surface. The outer peripheral member may be disposed on the extension region and bonded to the extension region via the bonding portion. The adhesive portion covers a region between an outer peripheral end of the gas diffusion layer and the adhesion portion of the outer peripheral member, and the adhesive member is located on the outer peripheral edge of the gas diffusion layer rather than the surface of the gas diffusion layer. The membrane electrode assembly may be formed before being sandwiched between the separators so as to have locally raised bulges. The separator may have a recess formed on the surface facing the gas diffusion layer so as to accommodate the raised portion. According to the fuel cell of this aspect, the adhesive member is disposed in the exposed region without a shortage so that the raised portion is formed in the adhesive portion. Moreover, since the raised portion is accommodated in a recess formed in advance in the separator, it is possible to suppress the stress from being generated in the membrane electrode assembly due to the raised portion.

  A plurality of constituent elements of each aspect of the present invention described above are not indispensable, and some or all of the effects described in the present specification are to be solved to solve part or all of the above-described problems. In order to achieve the above, it is possible to appropriately change, delete, replace with another new component, and partially delete the limited contents of some of the plurality of components. In order to solve part or all of the above-described problems or to achieve part or all of the effects described in this specification, technical features included in one embodiment of the present invention described above. A part or all of the technical features included in the other aspects of the present invention described above may be combined to form an independent form of the present invention.

  The present invention can also be realized in various forms other than the fuel cell. For example, it can be realized in the form of a manufacturing method of a fuel cell or an instrument or device used in the steps of the manufacturing method.

Schematic which shows the structure of a fuel cell. Schematic which shows the manufacturing process (1st process-3rd process) of a single cell. Schematic which shows the manufacturing process (4th process) of a single cell. Schematic which shows the manufacturing process (5th process) of a single cell. Schematic which shows the manufacturing process (6th process) of a single cell.

A. Embodiment:
FIG. 1 is a schematic diagram showing the configuration of a fuel cell 100 as an embodiment of the present invention. The fuel cell 100 is a polymer electrolyte fuel cell. The fuel cell 100 has a stack structure in which a plurality of single cells 10 are stacked. The single cell 10 is a power generator having a configuration capable of generating power independently. In the fuel cell 100, each single cell 10 is fastened in the stacking direction by a fastening member (not shown).

  Each single cell 10 includes a membrane electrode assembly 20, first and second gas diffusion layers 31 and 32, a frame-shaped member 40, an adhesive portion 50, and two separators 60. The membrane electrode assembly 20 includes an electrolyte membrane 21 and first and second electrodes 22 and 23. The electrolyte membrane 21 is composed of a thin film of an ion exchange resin (for example, perfluorosulfonic acid polymer) that exhibits good proton conductivity in a wet state.

  The first and second electrodes 22 and 23 are respectively disposed on the corresponding surfaces of the electrolyte membrane 21. Each electrode 22 is configured as a thin film layer having gas diffusibility and conductivity by conductive particles carrying a catalyst. In the present embodiment, each of the electrodes 22 and 23 is formed as a dry coating film of catalyst ink that is a dispersion solution of platinum-supporting carbon. In the fuel cell 100 of the present embodiment, the first electrode 22 functions as a cathode, and the second electrode 23 functions as an anode.

  The first gas diffusion layer 31 is stacked on the first electrode 22 of the membrane electrode assembly 20, and the second gas diffusion layer 32 is stacked on the second electrode 23 of the membrane electrode assembly 20. Has been. The first and second gas diffusion layers 31 and 32 are each composed of a base material (for example, carbon fiber) having gas diffusibility and conductivity.

  In this embodiment, the 1st gas diffusion layer 31 is comprised by the size smaller than the electrolyte membrane 21, and the whole outer periphery outline is the outer periphery outline of the electrolyte membrane 21 (the outer periphery outline of the membrane electrode assembly 20). ) Is disposed on the membrane electrode assembly 20 so as to be located on the inner peripheral side. As a result, the surface of the membrane electrode assembly 20 on the first electrode 22 side extends from the outer peripheral end of the first gas diffusion layer 31 and is an extended region ER that is a frame-shaped region surrounding the gas diffusion layer 31. Is formed. The extension region ER secures a distance between the end portions of the first and second gas diffusion layers 31 and 32, and a so-called cross leak occurs in which unreacted reaction gas flows back and forth between the two. Is suppressed.

  The frame-shaped member 40 corresponds to an outer peripheral member, and is disposed so as to surround the outer peripheral edge of the membrane electrode assembly 20. The frame-shaped member 40 has a function as a support part that supports the membrane electrode assembly 20 in the single cell 10 and a function as a seal part that suppresses leakage of fluid from the single cell 10. In this embodiment, the frame-shaped member 40 is comprised by resin members, such as a polypropylene (PP) and polyethylene (PE), for example.

  The frame-shaped member 40 has an outer peripheral portion 41 and an inner peripheral portion 42 having different thicknesses. The outer peripheral portion 41 is a portion located outside the outer peripheral end of the membrane electrode assembly 20 and is equal to or greater than the sum of the thickness of the membrane electrode assembly 20 and the thickness of the first and second gas diffusion layers 31 and 32. It has a thickness. The inner peripheral portion 42 is a sheet-like portion located inside the outer peripheral end of the membrane electrode assembly 20 and has a thickness equal to or smaller than the thickness of the first gas diffusion layer 31. The inner peripheral portion 42 corresponds to an adhesion site, is disposed on the outer peripheral edge portion included in the extension region ER of the membrane electrode assembly 20, and is bonded by the bonding portion 50.

  The bonding part 50 is a part constituted by an bonding member, and bonds the membrane electrode assembly 20 and the frame-shaped member 40 together. The adhesion part 50 is formed so as to cover the entire extension region ER of the membrane electrode assembly 20. This suppresses the electrolyte membrane 21 from being bent or damaged in the extended region ER that is not covered with the first gas diffusion layer 31. The bonding portion 50 is formed to have a raised portion 51 that is locally raised above the surface of the first gas diffusion layer 31. The reason why the adhesive portion 50 has the raised portion 51 in the fuel cell 100 of the present embodiment will be described later.

  The two separators 60 are conductive plate-like members arranged so as to sandwich the membrane electrode assembly 20. The two separators 60 sandwich the frame-shaped member 40 in the thickness direction, and are in surface contact with the first gas diffusion layer 31 or the second gas diffusion layer 32. On the inner surface of each separator 60 (the surface facing the membrane electrode assembly 20), a flow channel 61 for supplying a reaction gas to the power generation region or discharging exhaust gas from the power generation region is formed. Has been. The channel groove 61 corresponds to a recess and accommodates the raised portion 51 of the bonding portion 50.

  As will be described later, the adhesive portion 50 of this embodiment has been cured before the separator 60 is disposed on the first gas diffusion layer 31. Therefore, when the bonded portion 50 is formed before the separator 60 is arranged in the completed fuel cell 100, the raised portion 51 is not bonded to the inner wall surface of the flow channel groove 61 of the separator 60. That is, it is possible to determine whether or not the formation of the adhesive portion 50 is before the separator 60 is arranged based on the adhesion state of the raised portion 51.

  A manifold hole 70 is formed in the outer peripheral edge of the single cell 10 as a through hole that penetrates the two separators 60 and the frame member 40. The manifold hole 70 constitutes a manifold for allowing the reaction gas to flow through each unit cell 10 when the unit cell 10 is assembled to the fuel cell 100. The single cell 10 is formed with a communication path for a reactive gas that communicates the manifold hole 70 and the flow channel 61 of the separator 60 (illustration and detailed description are omitted).

  Thus, in the fuel cell 100 of the present embodiment, the membrane electrode assembly 20 and the frame member 40 are bonded by the bonding portion 50. The bonding portion 50 has a function of sealing the power generation region and a function of protecting the extension region ER of the membrane electrode assembly 20. In the fuel cell 100 of the present embodiment, as will be described below, in the manufacturing process of the single cell 10, the bonding portion 50 is formed to have the raised portion 51, so that the extension region ER by the bonding portion 50 is formed. The protection of is improved.

  The manufacturing process of the single cell 10 will be described in the order of steps with reference to FIGS. 2, 4, and 5 are illustrated by a schematic cross-sectional view similar to FIG. 1, and FIG. 3 illustrates the surface of the membrane electrode assembly 20 on the side where the first gas diffusion layer 31 is disposed. It is illustrated by a front view when viewed from a vertical direction.

  In the first step, a membrane electrode assembly 20 in which the first and second gas diffusion layers 31 and 32 are disposed on the first and second electrodes 22 and 23 is prepared (upper part of FIG. 2). . In the second step, a sufficient amount of the adhesive member 52 having fluidity before curing is applied to the extension region ER of the membrane electrode assembly 20 in consideration of the surplus enough to form a raised portion 51 described later. (Middle of FIG. 2).

  In the third step, the frame-shaped member 40 is disposed on the outer periphery of the membrane electrode assembly 20 (lower stage in FIG. 2). Specifically, the inner peripheral portion 42 of the frame-like member 40 is disposed on the region where the adhesive member 52 of the membrane electrode assembly 20 is applied, and the outer peripheral portion 41 contacts the outer peripheral end of the membrane electrode assembly 20. As described above, the frame member 40 is attached to the membrane electrode assembly 20 from the first gas diffusion layer 31 side. At this stage, the frame-like member 40 is not pressed so as to be completely fitted into the membrane electrode assembly 20 in order to suppress the protrusion due to the flow of the adhesive member 52.

  In the fourth step (FIG. 3), the adhesive member control plate 200, which is a jig for controlling the flow of the adhesive member 52, is stacked on the frame-shaped member 40 and the application region of the adhesive member 52. The adhesive member control plate 200 is configured by a combination of a first control plate 201 and a second control plate 202. In the present embodiment, each of the first control plate 201 and the second control plate 202 is configured by a plate-like member having the same thickness and substantially the same plate surface shape.

  The plate surfaces of the first and second control plates 202 each have a substantially L shape, and the first rectangular portion 203 and the second rectangular portion 204 having different lengths are orthogonal to each other at the ends. So that they are connected. The length of the first rectangular portion 203 is shorter than the length of the second rectangular portion 204. The first and second control plates 202 are arranged in combination so as to surround the outer periphery of the first gas diffusion layer 31. Specifically, it is as follows.

  In the present embodiment, the membrane electrode assembly 20 and the first gas diffusion layer 31 have a substantially rectangular shape, and are combined so that the directions along the long side and the short side thereof coincide with each other. . Each of the first and second control plates 201 and 202 is disposed such that the first rectangular portion 203 is adjacent to each of the two opposing short sides of the first gas diffusion layer 31. Further, the second rectangular portion 204 is disposed adjacent to each of the two opposing long sides of the first gas diffusion layer 31. That is, the first and second control plates 201 and 202 are arranged at positions that are opposite to each other so that the inner angles of the respective L shapes are fitted to the opposite corners of the first gas diffusion layer 31. The

  Here, the length of the short side of the first gas diffusion layer 31 is La, and the length of the side of the first rectangular portion 203 facing the short side of the first gas diffusion layer 31 is Lb. In the present embodiment, La> Lb. Accordingly, when the first and second control plates 201 and 202 are arranged as described above, gaps GP are generated between the first control plate 201 and the second control plate 202, respectively. The gap GP functions as an escape portion for the adhesive member 52 (described later). Note that the position where the gap GP is formed is defined in advance so as to correspond to the position where the flow channel 61 of the separator 60 is disposed.

  Incidentally, there may be a dimensional error in the size of the long side or the short side of the first gas diffusion layer 31. In the case of the adhesive member control plate 200 of the present embodiment, the dimensional error of the first gas diffusion layer 31 is absorbed and adjusted by the gap GP. Therefore, even when such a dimensional error occurs, the inner corner sides of the first and second control plates 201 and 202 can be arranged adjacent to the outer periphery of the first gas diffusion layer 31. Is possible.

  In the fifth step (FIG. 4), the first and second control plates 201 and 202 of the adhesive member control plate 200 are pressed in the thickness direction, and the frame-shaped member 40 is fitted into the outer peripheral portion of the membrane electrode assembly 20. To complete. By this step, the adhesive member 52 applied on the extended region ER is pressed by the frame-like member 40 and the adhesive member control plate 200 and flows so as to reach the entire extended region ER.

  The lower part of FIG. 4 schematically shows the state of the gap GP between the first and second control plates 201 and 202 when viewed in the direction of the arrow P shown in FIG. The surplus part of the adhesive member 52 applied to the extension region ER is the first and second control plates 201 and 202 described with reference to FIG. 3 by pressing between the frame-shaped member 40 and the adhesive member control plate 200. Flows into the gap GP between. As a result, a part of the adhesive member 52 rises from the surface of the first gas diffusion layer 31, and the raised portion 51 of the adhesive portion 50 is formed.

  Here, as described with reference to FIG. 3, the adhesive member control plate 200 according to the present embodiment has the first gas diffusion layer 31 in a region other than the gap GP even when a dimensional error has occurred. The gas diffusion layers 31 can be arranged so that no gap is generated between them. Therefore, according to the adhesive member control plate 200 of the present embodiment, it is possible to prevent the adhesive member 52 from sticking out of the first gas diffusion layer 31 or the like other than the portion where the gap GP is formed.

  After the adhesive member 52 is cured, the adhesive member control plate 200 is removed. In order to facilitate peeling from the adhesive member 52, it is desirable that the adhesive member control plate 200 be made of a material whose surface has releasability from the adhesive member 52. Specifically, the adhesive member control plate 200 may be constituted by a release sheet, or may be constituted by a plate-like member whose surface is Teflon-processed (“Teflon” is a registered trademark).

  In the sixth step (FIG. 5), one separator 60 is disposed on each side of the membrane electrode assembly 20. Each separator 60 may be bonded to the frame member 40. A channel groove 61 is formed in advance on the surface of each separator 60 facing the first or second gas diffusion layer 31, 32. The raised portion 51 formed in the bonding portion 50 is accommodated in the flow channel 61 of the separator 60. After this step, the manifold hole 70 (FIG. 1) is formed by punching the outer peripheral edge where the frame-shaped member 40 is disposed, and the single cell 10 is completed.

  As described above, according to the fuel cell 100 of the present embodiment, a sufficient amount of the adhesive member 52 in consideration of the surplus that the raised portion 51 is formed when the adhesive portion 50 is formed in the manufacturing process. Is applied. In addition, the adhesive member control plate 200 distributes the adhesive member 52 over the entire extension region ER in a state in which the adhesion of the adhesive member 52 to an unnecessary portion is suppressed. Therefore, the protection of the membrane electrode assembly 20 by the adhesive portion 50 and the sealing performance of the power generation region are enhanced.

  In addition, the formation position of the raised portion 51 in the bonding portion 50 is defined in advance by the bonding member control plate 200 at the position where the flow channel 61 of the separator 60 is disposed. Therefore, extra stress is generated in the membrane electrode assembly 20 and the first gas diffusion layer 31 due to the formation of the raised portion 51 in the adhesive portion 50, or the separator 60 and the first gas It is suppressed that the adhesiveness between the gas diffusion layers 31 falls.

B. Variation:
B1. Modification 1:
In the above embodiment, the raised portion 51 of the bonding portion 50 is accommodated in the flow channel 61 for the reactive gas formed in the separator 60. On the other hand, the raised portion 51 of the adhesive portion 50 may be accommodated in a recess other than the flow channel 61 formed in the separator 60. For example, the raised portion 51 of the bonding portion 50 may be accommodated in a recess only for accommodating the raised portion 51 formed in advance on the separator 60.

B2. Modification 2:
In the above embodiment, the adhesive member control plate 200 has a similar shape with a substantially L-shaped plate surface, and is configured by a combination of the first and second control plates 201 and 202 that are separated from each other. . On the other hand, the adhesive member control plate 200 may be configured by a combination of plate-like members having a plurality of different plate surface shapes separated into three or more. The adhesive member control plate 200 may be configured by a plurality of members that can be arranged adjacent to the outer periphery of the first gas diffusion layer 31 while having the gap GP. In addition, the position and number of formation of the gap GP and the interval of the gap GP are not particularly limited, and may be set as appropriate according to the configuration of the recess such as the flow channel 61 of the separator 60.

B3. Modification 3:
In the above embodiment, the frame-shaped member 40 is disposed on the outer periphery of the membrane electrode assembly 20. On the other hand, an outer peripheral member other than the frame-shaped member 40 may be disposed on the outer periphery of the membrane electrode assembly 20. For example, a plate-like channel member for constituting a reaction gas channel may be bonded to the outer periphery of the membrane electrode assembly 20 by the bonding part 50.

  The present invention is not limited to the above-described embodiments, examples, and modifications, and can be realized with various configurations without departing from the spirit thereof. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in each embodiment described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the above effects, replacement or combination can be performed as appropriate. Further, if the technical feature is not described as essential in the present specification, it can be deleted as appropriate.

DESCRIPTION OF SYMBOLS 10 ... Single cell 20 ... Membrane electrode assembly 21 ... Electrolyte membrane 22, 23 ... 1st and 2nd electrode 31, 32 ... 1st and 2nd gas diffusion layer 40 ... Frame-shaped member 41 ... Outer peripheral part 42 ... Inside Peripheral part 50 ... Adhesive part 51 ... Raised part 52 ... Adhesive member 60 ... Separator 61 ... Channel groove 70 ... Manifold hole 200 ... Adhesive member control plates 201 and 202 ... First and second control plates 203 and 204 ... first And second rectangular part GP ... gap

Claims (1)

A fuel cell,
A membrane electrode assembly in which electrodes are arranged on both surfaces of the electrolyte membrane;
A gas diffusion layer disposed on at least one electrode of the membrane electrode assembly;
An outer peripheral member disposed on an outer peripheral edge of the membrane electrode assembly;
An adhesive portion in which an adhesive member for adhering the outer peripheral member and the outer peripheral edge of the membrane electrode assembly is disposed;
A separator disposed to face the gas diffusion layer;
With
The outer peripheral edge of the membrane electrode assembly is located on the outer side of the gas diffusion layer by the outer peripheral contour of the gas diffusion layer being located inside the outer peripheral contour of the electrolyte membrane of the membrane electrode assembly. Has an extension area extending to
The outer peripheral member is disposed on the extension region, and is bonded to the extension region via the bonding portion,
The adhesive portion covers a region between an outer peripheral end of the gas diffusion layer and the adhesion portion of the outer peripheral member, and the adhesive member is located on the outer peripheral edge of the gas diffusion layer rather than the surface of the gas diffusion layer. Before the membrane electrode assembly is sandwiched between the separators so as to have a locally raised bulge,
The separator has a recess formed in a surface facing the gas diffusion layer so as to accommodate the raised portion.

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