JP2017188346A - Fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deformation generated in a gas diffusion layer.SOLUTION: A fuel battery includes: a membrane electrode assembly 202; an adhesive layer 400 formed like a frame on an outer peripheral edge of one face of the membrane electrode assembly 202; a resin frame member 300 having a frame shape and laminated so that an inner peripheral edge of the resin frame member is superposed in a state of contact with the outer peripheral edge of the adhesive layer 400; and a gas diffusion layer 206 arranged on the side inner than the inner peripheral edge of the resin frame member 300 and laminated so that the outer peripheral edge of the gas diffusion layer is superposed in a state of contact with the inner peripheral edge of the adhesive layer 400. The gas diffusion layer 206 has a microporous layer 210 formed on the outer peripheral edge of the gas diffusion layer 206, made of resin and formed like a frame, the microporous layer 210 is brought into contact with the inner peripheral edge of the adhesive layer 400 and an inner peripheral end of the microporous layer 210 is extended so as to be projected to the inner side inner than the inner peripheral end of the adhesive layer 400.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a fuel cell.

  In Patent Document 1, MEGA with a resin frame member having a frame-shaped resin frame member at the periphery of a membrane electrode gas diffusion layer assembly (MEGA) (hereinafter also referred to as “MEGA sheet”). ) Is disclosed. The resin frame member is formed by attaching the inner peripheral edge of the resin frame member to the outer peripheral edge of the adhesive applied in a frame shape to the peripheral edge of one surface of a membrane electrode assembly (MEA). Is formed integrally with the MEA at the peripheral edge of one surface of the MEA. The gas diffusion layer on the side on which the resin frame member is disposed is pressure-bonded by being disposed and pressed so that the peripheral edge of the gas diffusion layer overlaps the inner peripheral edge of the adhesive layer formed by curing, and the MEA And is integrally formed.

JP-A-2015-215958

  However, in the conventional MEGA sheet, when the gas diffusion layer is pressed and pressed against the cured adhesive layer, the gas diffusion layer may be deformed such as bending or bending.

  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 includes a membrane electrode assembly in which electrode catalyst layers are formed on both surfaces of an electrolyte membrane; an adhesive layer formed in a frame shape on the outer peripheral edge of one surface of the membrane electrode assembly; A resin frame member laminated so that an inner peripheral edge of the resin frame member is in contact with an outer peripheral edge of the adhesive layer; and the inner peripheral edge of the resin frame member A gas diffusion layer disposed on the inner side of the gas diffusion layer, wherein the gas diffusion layer is laminated so that an outer peripheral edge portion of the gas diffusion layer is in contact with an inner peripheral edge portion of the adhesive layer. . The gas diffusion layer has a resin-made frame-like microporous layer provided on the outer peripheral edge of the gas diffusion layer; the microporous layer is in contact with the inner peripheral edge of the adhesive layer And the inner peripheral end of the microporous layer protrudes inward from the inner peripheral end of the adhesive layer.
According to the fuel cell of this aspect, since the microporous layer is formed so as to protrude inward from the inner peripheral end of the adhesive layer inward from the outer peripheral end of the gas diffusion layer, the adhesive layer In addition, the strength of the gas diffusion layer against the stress of the pressure that presses the gas diffusion layer can be improved. For this reason, generation | occurrence | production of deformation | transformation of a gas diffusion layer laminated | stacked on the adhesive bond layer can be suppressed.

  In addition, this invention can be implement | achieved in various aspects, for example, can implement | achieve in aspects, such as a MEGA sheet | seat which has a fuel cell and a resin frame member, a manufacturing method of a fuel cell, a manufacturing method of a MEGA sheet | seat. it can.

It is explanatory drawing which shows the structure of the fuel cell using the MEGA sheet | seat which has a resin frame member as one Embodiment of this invention. It is explanatory drawing which expands and shows a part of MEGA sheet | seat. It is explanatory drawing which shows an example of the manufacturing process of a MEGA sheet. It is explanatory drawing which shows the structure characteristic of a MEGA sheet | seat. It is explanatory drawing which shows the effect by MPL. It is explanatory drawing which shows the other effect by MPL.

  FIG. 1 is an explanatory diagram showing a configuration of a fuel cell 700 using a MEGA sheet 100 having a resin frame member 300 as an embodiment of the present invention. In FIG. 1, a part of a cross-sectional configuration of the fuel cell stack 800 is illustrated. The fuel cell stack 800 has an integrated stack structure in which a plurality of stacked fuel cells 700 are fastened by a fastening member (not shown) in a state where a certain load is applied in the stacking direction. Each fuel cell 700 is a so-called polymer electrolyte fuel cell. Hereinafter, one fuel cell 700 is referred to as “single cell 700”.

  The single cell 700 includes a MEGA sheet 100 and an anode-side separator 500 and a cathode-side separator 600 that sandwich the MEGA sheet 100. The MEGA sheet 100 includes a rectangular membrane electrode gas diffusion layer assembly (MEGA) 200 and a rectangular frame-shaped resin frame member 300 disposed on the outer peripheral side of the MEGA 200. The MEGA 200 includes a rectangular membrane electrode assembly (MEA) 202 and a rectangular anode-side gas diffusion layer 204 and cathode-side gas diffusion layer 206 that sandwich the MEA 202. Hereinafter, the gas diffusion layer is also referred to as “GDL”.

  As will be described later, the resin frame member 300 is integrated with the MEGA 200 at the outer peripheral edge of the surface of the MEA 202 on the cathode side GDL 206 side. In the following description, the side where the cathode side GDL 206 of the MEA 202 is disposed may be simply referred to as “cathode side”, and the side where the anode side GDL 204 of the MEA 202 is disposed may be simply referred to as “anode side”.

  The anode separator 500 is formed with a flow path 502 for supplying hydrogen gas as a fuel gas to the anode of the MEGA 200. The cathode separator 600 has a flow path 602 for supplying air as an oxidizing gas to the cathode of the MEGA 200. Between the anode-side separator 500 of the single cell 700 and the cathode-side separator 600 of the adjacent single cell 700, water flow paths 504 and 604 as cooling media are formed.

  FIG. 2 is an explanatory view showing a part of the MEGA sheet 100 (the broken line frame part in FIG. 1) in an enlarged manner. The MEGA sheet 100 has a structure in which an inner peripheral edge of a frame-shaped resin frame member 300 is bonded to an outer peripheral edge of one surface of the MEGA 200 via an adhesive layer 400.

  The MEGA 200 has a structure in which a rectangular anode side GDL 204 is stacked on the anode side surface (lower surface in FIG. 2) of the MEA 202, and a rectangular cathode side GDL 206 is stacked on the cathode side surface (upper surface in FIG. 2) of the MEA 202. have. The MEA 202 has a rectangular anode-side electrode catalyst layer 24 formed on the anode-side surface of the rectangular electrolyte membrane 22, and a rectangular-shaped cathode-side electrode catalyst layer 26 formed on the cathode-side surface of the electrolyte membrane 22. It has a structure. The electrolyte membrane 22 is a proton conductive ion exchange membrane formed of a solid polymer material, for example, a fluororesin containing perfluorocarbon sulfonic acid, and exhibits good electrical conductivity in a wet state. Each of the anode-side electrode catalyst layer 24 and the cathode-side electrode catalyst layer 26 contains catalyst-carrying carbon carrying a catalyst such as platinum or a platinum alloy.

  Both the anode side GDL 204 and the cathode side GDL 206 are formed of a porous diffusion layer substrate. As the base material for the diffusion layer, for example, a carbon porous body (for example, carbon paper, carbon cloth, etc.) can be used. The anode GDL 204 is formed in a rectangular shape having the same size as the MEA 202 in plan view. On the other hand, the cathode side GDL 206 is formed in a rectangular shape that is slightly smaller than the MEA 202. For this reason, the MEA 202 has a protruding portion 201 that protrudes outside the cathode side GDL 206 in a state where the MEA 202 is combined with the anode side GDL 204 and the cathode side GDL 206. In other words, in the cross section of the MEGA sheet 100 shown in FIG. 2, the shape of the outer peripheral edge portion of the MEGA 200 is a step shape in which the MEA 202 protrudes outward from the cathode side GDL 206.

  For the resin frame member 300, for example, a resin member such as thermoplastic PP (polypropylene) is used. The resin frame member 300 is formed in a frame shape such that its inner peripheral edge overlaps the outer peripheral edge of the MEGA 200. In the resin frame member 300, instead of PP, for example, phenol resin, epoxy resin, PE (polyethylene, polyethylene), PET (polyethylene terephthalate), or a resin member in which a plurality of resins are laminated, for example, A three-layer resin member in which PP is laminated on both sides of PEN (Polyethylene naphthalate) may be used. Further, a thermosetting resin may be used for the resin frame member 300.

  The adhesive layer 400 is formed from the protruding portion 201 of the MEGA 200 to the outer peripheral edge portion of the cathode side GDL 206 inside the protruding portion 201. The adhesive layer 400 includes a side surface adhesion portion 401, a frame member adhesion portion 402, and a diffusion layer adhesion portion 403. The side adhesive portion 401 is a portion that bonds the inner peripheral side surface of the resin frame member 300 and the outer peripheral side surface of the cathode side GDL 206. The frame member bonding portion 402 is a portion that bonds the inner peripheral edge of the resin frame member 300. The diffusion layer bonding portion 403 is a portion that bonds the outer peripheral edge of the cathode side GDL 206. In addition, the resin frame member 300 is laminated so that the inner peripheral edge thereof is in contact with the frame member adhesive part 402 that is the outer peripheral edge part of the adhesive layer 400, so that the frame member adhesive part 402 and the side surface adhesive part 401 are overlapped. Is bonded to the outer peripheral edge of the cathode side surface of the MEA 202.

  The cathode side GDL 206 is laminated so that the outer peripheral edge thereof is in contact with the diffusion layer bonding portion 403 that is the inner peripheral edge of the adhesive layer 400, and the cathode side GDL 206 is interposed via the diffusion layer bonding portion 403 and the side surface bonding portion 401. The MEA 202 is bonded to the outer peripheral edge of the cathode side surface. The cathode side GDL 206 has a resinous microporous layer (hereinafter also referred to as “MPL”) 210 at a position in contact with the diffusion layer bonding portion 403 and the side surface bonding portion 401. The MPL 210 has a fine porous structure composed of fine holes having a diameter smaller than that of the cathode side GDL 206. The MPL 210 has an MPL flat surface portion 211 and an MPL side surface portion 212. The MPL flat surface portion 211 is a portion formed in a frame shape on the inner side from the outer peripheral end 209 of the flat surface 207 facing the MEA 202 side of the cathode side GDL 206. The MPL side surface portion 212 is a portion formed in a frame shape on the side surface 208 continuously to the MPL flat surface portion 211. The inner peripheral end of the MPL flat surface portion 211 protrudes inward from the inner peripheral end of the diffusion layer bonding portion 403 of the adhesive layer 400.

  As shown in FIG. 2, a gap corresponding to the thickness of the diffusion layer adhesion portion 403 of the adhesive layer 400 and the MPL plane portion 211 of the MPL 210 exists between the MEA 202 and the cathode side GDL 206. However, this gap is a load applied when the single cell 700 is assembled by sandwiching the MEGA sheet 100 between the separators 500 and 600, or a load applied when the fuel cell stack 800 is assembled by stacking a plurality of single cells 700. Is almost eliminated.

  FIG. 3 is an explanatory diagram illustrating an example of a manufacturing process of the MEGA sheet 100. FIG. 3 shows a cross section in the stacking direction of the MEA 202 and the GDLs 204 and 206.

  In step 1, the cathode GDL 206 on which the MPL 210 is formed is prepared. For example, the MPL 210 is formed by applying an MPL coating member to a region in the vicinity of the outer peripheral end 209 of the cathode side GDL 206 and drying it. As a coating method, for example, a screen printing method can be used. However, it is not limited to this, It can carry out using various coating methods. As the MPL coating member, for example, a paste member in which a conductive material, a binder, a dispersant, and a solvent are mixed and dispersed is used. Carbon, for example, carbon black is used as the conductive material. As the binder, a fluorine-based polymer material such as polytetrafluoroethylene (PTFE), or a resin member such as polypropylene or polyethylene is used. Of these materials, fluorine-based polymer materials, particularly PTFE, are preferably used. The solvent is not particularly limited, and various liquid agents such as water, methanol, ethanol and the like are used. The surfactant as the dispersant is not particularly limited, and various surfactants such as various nonionic surfactants such as ester type, ether type, ester / ether type and the like are used.

  In step 2, an MEA 202 having an anode side GDL 204 formed on the anode side surface is prepared. For example, the MEA 202 in which the anode side GDL 204 is formed can be prepared by placing the anode side GDL 204 on the anode side surface of the MEA 202 and performing hot pressing.

  In step 3, the adhesive layer 400 is formed by applying an adhesive in a frame shape to the outer peripheral edge on the cathode side of the MEA 202 on which the anode side GDL 204 is formed using any of various coating methods such as screen printing. Form. The adhesive constituting the adhesive layer 400 is, for example, a UV (ultraviolet) curable adhesive, and is an adhesive having a property of being cured by irradiating the application site with UV having a predetermined wavelength. The adhesive is preferably an adhesive containing polyisobutylene (PIB) having tackiness (tackiness) even after curing. For the adhesive, various adhesives such as adhesives of UV-curable elastomeric materials such as butyl rubber and thermosetting adhesives are used instead of the adhesive containing PIB. May be. In step 3, the adhesive layer 400 is still uncured.

  In step 4, the resin frame member 300 is pressed against the adhesive layer 400 so that the inner peripheral edge of the frame-shaped resin frame member 300 is in contact with the outer peripheral edge of the frame-shaped adhesive layer 400. The UV rays are irradiated toward the adhesive layer 400. As a result, the UV-irradiated adhesive layer 400 is cured, and the resin frame member 300 is fixed and integrated with the MEA 202 via the frame member adhesive portion 402 and the side surface adhesive portion 401 of the adhesive layer 400. The cured adhesive layer 400 preferably has tackiness (adhesiveness) as described above.

  In step 5, the cathode side GDL 206 is overlapped in a state where the cathode side GDL 206 is turned upside down with respect to step 1 and the outer peripheral edge of the cathode side GDL 206 on which the MPL 210 is formed is in contact with the inner peripheral edge of the adhesive layer 400. And press at room temperature. As a result, the inner peripheral edge of the adhesive layer 400 is crushed by the MPL 210 of the cathode side GDL 206 to form the diffusion layer adhesion portion 403 and the side surface adhesion portion 401. The diffusion layer adhesion portion 403 and the side surface adhesion portion 401 thus formed are Then, the cathode side GDL 206 is bonded and integrated with the MEA 202, and the MEGA sheet 100 is manufactured.

  FIG. 4 is an explanatory view showing the structural features of the MEGA sheet 100. 4A is an enlarged view of the outer peripheral edge of the cathode side GDL 206, and is a cross-sectional view similar to FIG. The inner peripheral edge of the MPL flat surface portion 211 of the MPL 210 is in a state of extending so as to protrude inward from the inner peripheral edge of the diffusion layer bonding portion 403 of the adhesive layer 400 (both clearances Cw are larger than 0). Yes. The state of Cw> 0 can be adjusted by adjusting the width of the MPL plane portion 211 or adjusting the application range of the adhesive layer 400.

  FIG. 4B shows a first comparative example. As illustrated in FIG. 4B, when the adhesive layer 400 is formed only on the side surface of the cathode side GDL 206, there is a high possibility that the inner peripheral end of the MPL flat surface portion 211 bites into the cathode side GDL 206. Moreover, since the area | region which contacts the adhesive bond layer 400 becomes only the side surface of the cathode side GDL206, adhesive strength reduces.

  FIG. 4C shows a second comparative example. As shown in FIG. 4C, even when the inner peripheral end of the diffusion layer bonding portion 403 protrudes inward from the inner peripheral end of the MPL plane portion 211, the inner peripheral end of the MPL plane portion 211 is There is a high risk of biting into the cathode side GDL 206.

  On the other hand, in this embodiment, as shown in FIG. 4A, the inner peripheral end of the MPL plane portion 211 protrudes inward from the inner peripheral end of the diffusion layer bonding portion 403 of the adhesive layer 400. State (Cw> 0). For this reason, the stress with respect to the pressure added to the cathode side GDL206 is disperse | distributed to the part corresponding to the MPL plane part 211, and there is little possibility that the inner peripheral end of the MPL plane part 211 will bite into the cathode side GDL206. Thereby, the intensity | strength with respect to the pressure added to the cathode side GDL206 can be raised.

  As shown in FIG. 4A, the height from the MEA 202 of the side surface adhesion portion 401 of the adhesive layer 400 is lower than the height from the MEA 202 of the cathode side GDL 206 (the clearance Ch between the two is 0). Larger). The state of Ch> 0 can be adjusted by adjusting the coating amount (thickness) of the adhesive layer 400. This is to prevent the adhesive layer 400 from adhering to the cathode-side separator 600 (FIG. 1) and closing the gas flow path 602 when the adhesive layer 400 is higher than the cathode-side GDL 206. It is.

  FIG. 5 is an explanatory diagram showing the effect of the MPL 210. FIG. 5A shows a case where a cathode side GDL 206 in which the MPL 210 is not formed is used as a third comparative example. When the cathode side GDL 206 is arranged and pressed at room temperature so that the outer peripheral edge portion of the cathode side GDL 206 overlaps the inner peripheral edge portion of the adhesive layer 400, the cathode side GDL 206 is deformed such as bending or bending due to stress against pressure. there is a possibility.

  On the other hand, when the cathode side GDL 206 in which the MPL 210 is formed is used, the stress is dispersed by the MPL 210 as described with reference to FIG. 4, so that the strength of the cathode side GDL 206 can be improved. is there. As a result, as shown in FIG. 5B, the diffusion layer adhesion portion 403 and the frame member adhesion portion 402 formed by crushing the inner peripheral edge of the adhesive layer 400 while suppressing deformation of the cathode side GDL 206. The cathode side GDL 206 can be attached to the MEA 202 via

  FIG. 6 is an explanatory diagram showing another effect of the MPL 210. In FIG. FIG. 6A shows a case where a cathode side GDL 206 in which the MPL 210 is not formed is used as a fourth comparative example. When the cathode side GDL 206 is arranged and pressed at room temperature so that the outer peripheral edge portion of the cathode side GDL 206 overlaps the inner peripheral edge portion of the adhesive layer 400, the adhesive layer 400 may be embedded in the cathode side GDL 206. In this case, the adhesive strength against the stress generated by the gas flowing through the gas flow path in the single cell 700 in which the MEGA sheet 100 is incorporated may be insufficient, and the cathode side GDL 206 may be peeled off.

  On the other hand, when the cathode side GDL 206 in which the MPL 210 is formed is used, as shown in FIG. 6B, the MPL 210 becomes a wall, and the adhesive layer 400 sinks into the cathode side GDL 206. Can be suppressed. Moreover, by crushing the adhesive layer 400 to form the diffusion layer adhesion portion 403, it is possible to suppress a decrease in the adhesion area between the cathode side GDL 206 and the adhesive layer 400, and to reduce the adhesion strength. Can be suppressed. And it can suppress that cathode side GDL206 peels by the stress which generate | occur | produces with the flow of gas.

  As described above, in the single cell 700 using the MEGA sheet 100 of the present embodiment, it is possible to suppress the problem of deformation and peeling of the cathode side GDL 206.

  Note that the MPL side surface 212 (FIG. 2) of the MPL 210 may be omitted. Even if the MPL side surface portion 212 is omitted, the effect of suppressing the deformation of the cathode side GDL 206 is the same. However, it is preferable that the MPL side surface portion 212 is formed in that the effect of suppressing the adhesive layer 400 from sinking into the side surface of the cathode side GDL 206 is enhanced.

  Further, in the above-described embodiment, the MEGA sheet 100 has the protrusion 201 on the cathode side of the MEA 202, and the resin frame member 300 is provided on the outer peripheral edge of the MEA 202 on the cathode side (FIG. 2). However, the MEGA sheet may have a configuration in which a protrusion is provided on the anode side of the MEA and a resin frame member is provided on the outer peripheral edge of the MEA on the anode side. In this case, the MPL 210 may be provided on the anode side GDL 204 in the same manner as the cathode side GDL 206 shown in FIG. In addition, the MEGA sheet may have a configuration in which protrusions are provided on both sides of the MEA, and a resin frame member is provided on the outer peripheral edge of each MEA. In this case, the MPL 210 may be provided on both the anode side GDL 204 and the cathode side GDL 206.

  In the above-described embodiment, the MEGA sheet 100 has the cathode-side electrode catalyst layer 26 formed on the cathode-side protrusion 201 of the MEA 202, and the resin frame member 300 is formed on the outer peripheral edge of the cathode-side electrode catalyst layer 26. The configuration was provided. However, the MEGA sheet may be configured such that the cathode-side electrode catalyst layer 26 is not formed on the outer peripheral edge of the protrusion 201 and the resin frame member 300 is provided on the outer peripheral edge of the electrolyte membrane 22.

  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-described 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 22 ... Electrolyte membrane 24 ... Anode side electrode catalyst layer 26 ... Cathode side electrode catalyst layer 100 ... MEGA sheet 200 ... Membrane electrode gas diffusion layer assembly (MEGA)
201 ... protrusion 202 ... membrane electrode assembly (MEA)
204 ... Anode side gas diffusion layer (anode side GDL)
206 ... Cathode side gas diffusion layer (cathode side GDL)
207 ... Planar 208 ... Side 209 ... Outer peripheral edge 210 ... Microporous layer (MPL)
211 ... MPL flat surface portion 212 ... MPL side surface portion 300 ... resin frame member 400 ... adhesive layer 401 ... side surface adhesive portion 402 ... frame member adhesive portion 403 ... diffusion layer adhesive portion 500 ... anode side separator 502 ... flow path 600 ... cathode side Separator 602 ... flow path 504, 604 ... flow path 700 ... single cell (fuel cell)
800 ... Fuel cell stack

Claims (1)

A fuel cell,
A membrane electrode assembly in which electrode catalyst layers are formed on both surfaces of the electrolyte membrane;
An adhesive layer formed in a frame shape on the outer peripheral edge of one surface of the membrane electrode assembly;
A resin frame member having a frame shape, wherein the resin frame member is laminated so that the inner peripheral edge of the resin frame member is in contact with the outer peripheral edge of the adhesive layer;
A gas diffusion layer disposed inside the inner peripheral edge of the resin frame member, wherein the outer peripheral edge of the gas diffusion layer is stacked so as to overlap with the inner peripheral edge of the adhesive layer. Gas diffusion layer,
With
The gas diffusion layer has a resin-made frame-like microporous layer provided on the outer peripheral edge of the gas diffusion layer;
The fuel cell, wherein the microporous layer is in contact with the inner peripheral edge of the adhesive layer, and an inner peripheral end of the microporous layer protrudes inward from an inner peripheral end of the adhesive layer.

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