JP2008034156A - Fuel cell - Google Patents

Abstract

An object of the present invention is to provide a technique for preventing separation of an electrolyte membrane of a seal gasket-integrated MEA and a seal member in a fuel cell stack.
A seal gasket-integrated MEA 45A includes a joining member 458. The plurality of joining members 458 </ b> A each have a cylindrical shape, and are arranged at equal intervals on the peripheral edge of the MEA portion 451. Further, the joining member 458A penetrates the MEA portion 451. And the seal gasket 450 is integrally formed in the outer periphery of the MEA part 451 in the state which covers the peripheral part of the MEA part 451, and the some joining member 458A arrange | positioned at the peripheral part.
[Selection] Figure 3

Description

  The present invention relates to a fuel cell, and in particular, a MEA (membrane electrode assembly) in which catalyst electrodes are formed on both surfaces of a polymer electrolyte membrane and a seal member are integrally formed, and a separator is formed. The present invention relates to a fuel cell having a stack structure in which they are stacked.

A conventional polymer electrolyte membrane fuel cell employs an MEA system in which catalyst electrodes are formed on both sides of a polymer electrolyte membrane. There is a fuel cell having a laminated structure in which separators provided with gas flow paths for fuel gas and oxidant gas are provided on each surface and MEAs are alternately laminated.
In such a fuel cell, in order to prevent leakage of fuel gas and oxidant gas, a technique for integrally forming an MEA and a seal member has been proposed (for example, Patent Document 1).

JP 2001-102072 A

During operation of the fuel cell, hydrogen gas is divided into hydrogen ions (H ⁺ ) and electrons (e ⁻ ) at the hydrogen electrode, and the hydrogen ions move from the hydrogen electrode side to the oxygen electrode side in the polymer electrolyte membrane. Here, water is necessary for hydrogen ions to move within the polymer electrolyte membrane. Therefore, in order for the polymer electrolyte membrane to ensure sufficient hydrogen ion conductivity, the polymer electrolyte membrane is managed so that a sufficient amount of moisture is contained in the membrane. Therefore, when the fuel cell is in operation, the polymer electrolyte membrane contains sufficient moisture. However, if the polymer electrolyte membrane contains a large amount of moisture until the fuel cell is stopped, for example, when starting at a low temperature, the electrolyte membrane may freeze and the fuel cell may not be operated. Therefore, when the fuel cell is stopped, the electrolyte membrane is purged and dried. Thus, the polymer electrolyte membrane contracts because the wet state of the polymer electrolyte membrane changes with the operation and stop of the fuel cell.
Further, during operation of the fuel cell, the temperature of the polymer electrolyte membrane rises as compared with when the fuel cell is stopped due to self-heating of the fuel cell. Thus, the polymer electrolyte membrane contracts also due to the temperature change of the polymer electrolyte membrane accompanying the operation and stop of the fuel cell.

  On the other hand, the seal member is mainly formed using an elastic material such as rubber, but contracts due to the difference between the molding temperature at the time of formation and the normal temperature. Further, rubber or the like forms a cross-linked structure by chemical bond formation (cross-linking) between polymer chains in the curing process, but the seal member contracts also by the cross-linking reaction.

Thus, both the polymer electrolyte membrane and the seal member can contract. Here, since the shrinkage rate of the electrolyte membrane is larger than the shrinkage rate of the seal member, even if the MEA and the seal member are integrally formed, the adhesion portion between the seal member and the polymer electrolyte membrane may be peeled off. . As a result, the fuel gas and the oxidant gas may cross leak.
When fuel gas and oxidant gas cross-leak, hydrogen used as fuel gas does not react with the catalyst, but reacts directly with oxygen, resulting in poor electrochemical reaction efficiency of hydrogen and poor power generation efficiency. There was a problem.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art and to provide a technique for preventing peeling of the electrolyte membrane and the seal member.

  In order to solve at least a part of the above-described problems, a fuel cell according to the present invention includes a membrane electrolyte assembly (MEA) having at least a polymer electrolyte membrane and electrodes formed on both sides of the polymer electrolyte membrane, and a separator. A fuel cell having a stack structure in which a plurality of layers are interposed and a joining member having a plurality of electrolyte membrane penetrating portions penetrating at least a part of a peripheral portion of the polymer electrolyte membrane, and at least one of the joining members And a sealing member formed integrally with the MEA so as to cover the portion and the peripheral edge of the polymer electrolyte membrane.

  In this specification, MEA (Membrance Electrode Assembly) is a membrane electrode assembly having at least a polymer electrolyte membrane (hereinafter simply referred to as “electrolyte membrane”) and electrodes formed on both surfaces of the electrolyte membrane. Say. Furthermore, in order to ensure gas diffusibility or current collecting property, a diffusion layer made of a porous conductive member may be provided on the electrode.

  Moreover, the peripheral part of a polymer electrolyte membrane means the range with the width | variety containing not only an edge but an edge. That is, the joining member may be disposed at the end of the electrolyte membrane along the periphery of the polymer electrolyte membrane. Further, for example, in the case where a plurality of through holes forming a manifold through which a fuel gas, an oxidant gas, or a cooling medium can flow are provided in the peripheral portion of the polymer electrolyte membrane, the through holes are provided in the polymer electrolyte. You may make it arrange | position at an edge along the periphery of a film | membrane, and also arrange | position a joining member inside it.

  Moreover, the electrolyte membrane penetration part of a joining member may penetrate only an electrolyte membrane, and may penetrate an electrolyte membrane and an electrode. For example, in the MEA, the electrode may be formed smaller than the electrolyte membrane, the electrode may be disposed so that the peripheral edge of the electrolyte membrane protrudes from the electrode, and the electrolyte membrane penetrating portion may penetrate the exposed peripheral edge portion of the electrolyte membrane. . In this case, if the seal member is formed integrally with the MEA so as to cover only the joining member and the electrolyte membrane, the electrode may be deformed or damaged due to a temperature change at the time of forming the seal member. Can be prevented, which is preferable.

  Moreover, since the sealing member is formed so as to cover at least a part of the joining member, the whole joining member may be included in the sealing member, for example, the electrolyte membrane penetrating portion also penetrates the sealing member. It may be formed as follows.

  As described above, according to the fuel cell of the present invention, the sealing member is integrally formed with the electrolyte membrane in a state where the joining member penetrates the electrolyte membrane. Therefore, the sealing member and the electrolyte membrane are bonded, and further, the sealing member and the electrolyte membrane are bonded by the bonding member. Therefore, even if the seal member and the electrolyte membrane are each contracted, since the seal member and the electrolyte membrane are joined by the joining member, the shrinkage of the seal member and the electrolyte membrane is limited, and the bonded seal member and the electrolyte membrane are bonded. And peeling can be prevented. Therefore, since it is possible to prevent the fuel gas and the oxidant gas from cross leaking, it is possible to prevent the abnormal combustion from being caused by the direct reaction between the fuel gas and the oxidant gas. Further, the direct reaction between the fuel gas and the oxidant gas can reduce the reaction efficiency of the fuel gas in the catalyst and prevent the power generation efficiency from decreasing.

  In the fuel cell of the present invention, the joining member may further include a frame portion formed so as to go around in a frame shape, and the electrolyte membrane penetration portion may protrude from the frame portion. .

  As described above, according to the fuel cell of the present invention, by the joining member having the frame portion formed so as to go around the periphery of the electrolyte membrane in a frame shape and the electrolyte membrane penetrating portion protruding from the frame portion. The electrolyte membrane and the sealing member are joined. Therefore, peeling of the electrolyte membrane and the seal member can be prevented over the entire circumference of the electrolyte membrane.

  In the fuel cell of the present invention, at least the frame portion of the joining member may be made of a highly rigid material having higher rigidity than the seal member.

  In order to obtain sealing performance, the sealing member often uses a material having a low Young's modulus (that is, low rigidity and softness) such as rubber. When forming the seal member, for example, according to injection molding, the seal member may be deformed so as to wave due to a temperature change or a crosslinking reaction during molding. In such a case, according to the fuel cell of the present invention, the sealing member is formed so as to cover the joining member, and the frame portion of the joining member has higher rigidity than the sealing member, so that the shrinkage of the sealing member is limited, The deformation of the sealing member as described above can be suppressed.

  In the fuel cell, the seal member has a plurality of through holes that form a manifold through which a fuel gas, an oxidant gas, or a cooling medium can circulate when a plurality of the MEAs are stacked via the separator. The frame portion may be formed such that the through hole is located on an outer periphery of the frame portion.

  As described above, according to the fuel cell of the present invention, the plurality of through holes formed in the seal member and forming the manifold through which the fuel gas, the oxidant gas, or the cooling medium can flow are formed in the frame portion. It is located on the outer periphery. When the frame portion is disposed at the end of the peripheral edge of the MEA, a seal member can be formed on the outer periphery of the MEA, and the outer shape of the MEA can be formed smaller than the seal member. Therefore, the expensive MEA can be reduced, and the cost of the fuel cell can be reduced.

  In the fuel cell of the present invention, at least the frame part may be included in the seal member.

  As described above, according to the fuel cell of the present invention, at least the frame portion is included in the seal member. When the seal member is formed integrally with the MEA in which the joining member is disposed, the frame portion of the joining member is bonded to the seal member. Therefore, compared with the case where the frame part is not included in the seal member and the bonding member is provided in a state of protruding from the seal member, for example, the frame part is not bonded to the seal member, so that the bonding member is sealed. It is prevented from falling off from the member and the electrolyte membrane, and the joining between the electrolyte membrane and the seal member can be further strengthened.

  According to the fuel cell of the present invention, the electrolyte membrane penetrating portion may be made of an insulating material that penetrates at least the polymer electrolyte membrane and the electrode.

  As described above, according to the fuel cell of the present invention, the electrolyte membrane penetration part of the joining member may penetrate at least the electrolyte membrane and the electrode, and may also penetrate the diffusion layer. In MEA, it is suitable when the electrolyte membrane, the electrode, and the diffusion layer are formed in the same size and stacked. In this case, since the electrode and the diffusion layer are conductive members, it is possible to prevent a short circuit of electricity generated at the electrodes by making the electrolyte membrane penetrating portion of the joining member insulative.

  According to the fuel cell of the present invention, the joining member further includes a fitting portion that fits at least a part of a peripheral edge of the separator when the MEA is stacked with the separator interposed therebetween. The electrolyte membrane penetration part and the fitting part may be insulated.

As described above, according to the fuel cell of the present invention, when the MEA is stacked with the separator interposed, the fitting portion of the joining member can be fitted to a part of the peripheral edge of the separator. By fitting the fitting part of the joining member to a part of the peripheral part of the separator, the position in the surface direction of the MEA and the separator is fixed, so that the MEA and the separator can be easily and accurately stacked. A fuel cell having a stack structure can be easily produced. That is, as described above, the joining member has an effect of preventing the sealing member and the electrolyte membrane from being peeled and facilitating the positioning of the MEA and the separator in the surface direction.
In addition, since the separator uses a conductive material, when the fitting part of the joining member is fitted with the peripheral part of the separator, it is generated if the electrolyte membrane penetration part and the fitting part are not insulated. May cause a short circuit. In such a case, the generated electricity can be prevented from being short-circuited by the insulation between the electrolyte membrane penetrating portion and the fitting portion of the joining member.

Hereinafter, the best mode for carrying out the present invention will be described in the following order based on examples.
A. First embodiment:
A1. Fuel cell stack configuration:
A2. Fuel cell module:
A2.1. Separator:
A2.2. Seal gasket integrated MEA:
B. Second embodiment:
C. Third embodiment:
D. Fourth embodiment:
E. Variation:

A. First embodiment:
A1. Fuel cell stack configuration:
FIG. 1 is a perspective view showing a schematic configuration of a fuel cell stack 100 as a first embodiment of the present invention. The fuel cell stack 100 has a stack structure in which a plurality of cells that generate electricity by an electrochemical reaction between hydrogen and oxygen are stacked with a separator interposed therebetween. As will be described later, each cell has a configuration in which an anode and a cathode are arranged with an electrolyte membrane having proton conductivity interposed therebetween. In this example, a solid polymer membrane was used as the electrolyte membrane. Another electrolyte such as a solid oxide may be used as the electrolyte. Note that the number of stacked cells can be arbitrarily set according to the output required for the fuel cell stack 100.

  The fuel cell stack 100 is configured by stacking an end plate 10, an insulating plate 20, a current collecting plate 30, a plurality of fuel cell modules 40, a current collecting plate 50, an insulating plate 60, and an end plate 70 in this order from one end. Yes. These are provided with a supply port, a discharge port, and a flow path (not shown) for flowing hydrogen as a fuel gas, air as an oxidant gas, and cooling water in the fuel cell stack 100. Hydrogen is supplied from a hydrogen tank (not shown). Air and cooling water are pressurized and supplied by a pump (not shown). The fuel cell module 40 is composed of a membrane electrode assembly (hereinafter referred to as “MEA”) and a seal gasket-integrated MEA 45A integrally provided with a seal gasket, and a separator 41, which will be described later. The fuel cell module 40 and the seal gasket-integrated MEA 45A will be described later.

  The fuel cell stack 100 is also provided with a tension plate 80 as shown. In the fuel cell stack 100, in order to suppress a decrease in battery performance due to an increase in contact resistance or the like in any part of the stack structure, and to obtain sufficient sealing performance of the seal gasket-integrated MEA 45A, A pressing force is applied in the direction, and the tension plate 80 is fixed to the end plates 10 and 70 at both ends of the fuel cell stack 100 by bolts 82, whereby each fuel cell module 40 is fastened with a predetermined fastening force in the stacking direction. ing.

  Note that the end plates 10 and 70 and the tension plate 80 are made of metal such as steel in order to ensure rigidity. The insulating plates 20 and 60 are formed of an insulating member such as rubber or resin. The current collecting plates 30 and 50 are formed of dense carbon or a gas impermeable conductive member such as a copper plate. The current collector plates 30 and 50 are each provided with an output terminal (not shown) so that the power generated by the fuel cell stack 100 can be output.

A2. Fuel cell module:
As described above, the fuel cell module 40 includes the separator 41 and the seal gasket-integrated MEA 45A. Hereinafter, the separator 41 and the seal gasket-integrated MEA 45A will be described.

A2.1. Separator:
FIG. 2 is a plan view of the component parts of the separator 41 and the separator 41. The separator 41 in this embodiment is composed of three metal flat plates each having a plurality of through holes, that is, a cathode facing plate 42, an intermediate plate 43, and an anode facing plate 44. The separator 41 is manufactured by superimposing the cathode facing plate 42, the intermediate plate 43, and the anode facing plate 44 in this order and performing hot press bonding. In this embodiment, the cathode facing plate 42, the intermediate plate 43, and the anode facing plate 44 are made of stainless steel flat plates having the same rectangular shape. As the cathode facing plate 42, the intermediate plate 43, and the anode facing plate 44, flat plates made of other metal such as titanium or aluminum may be used instead of stainless steel. Further, as the intermediate plate 43, a resin plate may be used.

  FIG. 2A is a plan view of the cathode facing plate 42 that contacts the surface on the cathode side of the seal gasket-integrated MEA 45A. As illustrated, the cathode facing plate 42 includes an air supply through hole 422a, a plurality of air supply ports 422i, a plurality of air discharge ports 422o, an air discharge through hole 422b, and a hydrogen supply through hole 424a. , A hydrogen discharge through hole 424b, a cooling water supply through hole 426a, and a cooling water discharge through hole 426b are provided. In this embodiment, the air supply through hole 422a, the air discharge through hole 422b, the hydrogen supply through hole 424a, the hydrogen discharge through hole 424b, the cooling water supply through hole 426a, and the cooling water discharge The through hole 426b has a substantially rectangular shape, and the plurality of air supply ports 422i and the plurality of air discharge ports 422o have a circular shape with the same diameter.

  FIG. 2B is a plan view of the anode facing plate 44 that comes into contact with the surface on the anode side of the seal gasket-integrated MEA 45A. As illustrated, the anode facing plate 44 includes an air supply through hole 442a, an air discharge through hole 442b, a hydrogen supply through hole 444a, a plurality of hydrogen supply ports 444i, and a plurality of hydrogen discharge ports 444o. , A hydrogen discharge through hole 444b, a cooling water supply through hole 446a, and a cooling water discharge through hole 446b are provided. In this embodiment, the air supply through hole 442a, the air discharge through hole 442b, the hydrogen supply through hole 444a, the hydrogen discharge through hole 444b, the cooling water supply through hole 446a, and the cooling water discharge The through hole 446b is substantially rectangular, and the plurality of hydrogen supply ports 444i and the plurality of hydrogen discharge ports 444o are circular with the same diameter.

  FIG. 2C is a plan view of the intermediate plate 43. As shown in the figure, the intermediate plate 43 includes an air supply through hole 432a, an air discharge through hole 432b, a hydrogen supply through hole 434a, a hydrogen discharge through hole 434b, and a plurality of cooling water flow path forming through holes. Hole 436. The air supply through hole 432a is provided with a plurality of air supply flow path forming portions 432c for flowing air from the air supply through hole 432a to the plurality of air supply ports 422i of the cathode facing plate 42, respectively. ing. The air discharge through hole 432b is provided with a plurality of air discharge flow path forming portions 432d for flowing air from the plurality of air discharge ports 422o of the cathode facing plate 42 to the air discharge through hole 432b. . The hydrogen supply through hole 434a is provided with a plurality of hydrogen supply flow path forming portions 432e for flowing hydrogen from the hydrogen supply through hole 434a to the plurality of hydrogen supply ports 444i of the anode facing plate 44, respectively. ing. The hydrogen discharge through hole 434b is provided with a plurality of hydrogen discharge flow path forming portions 432f for flowing hydrogen from the plurality of hydrogen discharge ports 444o of the anode facing plate 44 to the hydrogen discharge through hole 434b. .

  FIG. 2D is a plan view of the separator 41. Here, the top view seen from the anode opposing plate 44 side was shown.

  As can be seen from the figure, in the anode facing plate 44, the intermediate plate 43, and the cathode facing plate 42, the air supply through hole 442a, the air supply through hole 432a, and the air supply through hole 422a are the same. Formed in position. The air discharge through hole 442b, the air discharge through hole 432b, and the air discharge through hole 422b are also formed at the same position. Further, the hydrogen supply through-hole 444a, the hydrogen supply through-hole 434a, and the hydrogen supply through-hole 424a are also formed at the same position. Further, the hydrogen discharge through hole 444b, the hydrogen discharge through hole 434b, and the hydrogen discharge through hole 424b are also formed at the same position.

  Further, in the anode facing plate 44 and the cathode facing plate 42, the cooling water supply through-hole 446a and the cooling water supply through-hole 426a are formed at the same position. The cooling water discharge through-hole 446b and the cooling water discharge through-hole 426b are also formed at the same position.

  In addition, in the intermediate plate 43, one end of each of the plurality of cooling water flow path forming through holes 436 has a cooling water supply through hole 446 a in the anode facing plate 44 and a cooling water supply through hole in the cathode facing plate 42. While overlapping with the hole 426 a, the other end is formed so as to overlap with the cooling water discharge through hole 446 b of the anode facing plate 44 and the cooling water discharge through hole 426 b of the cathode facing plate 42.

  The widths of the air supply flow path forming part 432c, the air discharge flow path forming part 432d, the hydrogen supply flow path forming part 432e, and the hydrogen discharge flow path forming part 432f in the intermediate plate 43 are respectively the cathode facing plate. The diameters of the air supply port 422i, the air discharge port 422o, and the hydrogen supply port 444i and the hydrogen discharge port 444o of the anode facing plate 44 are set larger. By doing so, when the cathode facing plate 42, the intermediate plate 43, and the anode facing plate 44 are joined together by being overlapped, even if they are slightly displaced, air and hydrogen can be flowed in a desired path. .

  In this separator 41, the flow of hydrogen, air, and cooling water is as follows. That is, the hydrogen flowing through the hydrogen supply through hole 424 a of the cathode facing plate 42, the hydrogen supply through hole 434 a of the intermediate plate 43, and the hydrogen supply through hole 444 a of the anode facing plate 44 Branches from 434a, passes through a plurality of hydrogen supply flow path forming portions 432e, and is perpendicular to the anode of the MEA portion 451 of the seal gasket-integrated MEA 45A described later from the plurality of hydrogen supply ports 444i of the anode facing plate 44. Supplied in the direction. Then, the anode off gas discharged from the anode is discharged through the plurality of 444o of the anode facing plate 44 and the hydrogen discharge flow path forming portion 432f of the intermediate plate 43.

  The air flowing through the air supply through-hole 442a of the anode facing plate 44, the air supply through-hole 432a of the intermediate plate 43, and the air supply through-hole 422a of the cathode facing plate 42 are passed through the air supply through-hole of the intermediate plate 43. Branches from 432a, passes through an air supply flow path forming portion 432c, and passes through a plurality of air supply ports 422i of the cathode facing plate 42 in a direction perpendicular to the cathode of the MEA portion 451 of the seal gasket-integrated MEA 45A described later. Supplied. The cathode off-gas discharged from the cathode is discharged through a plurality of air discharge ports 422o of the cathode facing plate 42 and 432d of the intermediate plate 43.

  Further, the cooling water flowing through the cooling water supply through hole 446a of the anode facing plate 44, one end of the plurality of cooling water flow path forming through holes 436 of the intermediate plate 43, and the cooling water supply through hole 426a of the cathode facing plate 42 are: It branches from the cooling water flow path forming through hole 436 of the intermediate plate 43, passes through the intermediate plate 43, and is discharged from the other end of the cooling water flow path forming through hole 436.

A2.2. Seal gasket integrated MEA:
FIG. 3 is an explanatory view showing a seal gasket-integrated MEA 45A. FIG. 3A shows a plan view of the seal gasket-integrated MEA 45A as viewed from the cathode side. FIG. 3B shows a cross-sectional view taken along the line AA in FIG. FIG. 3C is a cross-sectional view taken along line BB in FIG. The outer shape of the seal gasket-integrated MEA 45A is formed by cutting out the four corners of the outer shape of the separator 41.

  The MEA portion 451 has a substantially square shape as shown in FIG. 3C, and, as shown in FIG. 3B, on one surface of the electrolyte membrane 46, the cathode side catalyst electrode 47c and The cathode diffusion layer 48c is laminated in this order, and the anode side catalyst electrode 47a and the anode diffusion layer 48a are laminated in this order on the other surface. In this embodiment, porous carbon is used as the anode diffusion layer 48a and the cathode diffusion layer 48c.

  As shown in FIG. 3A, the seal gasket 450 includes an air supply through hole 452a, a hydrogen supply through hole 454a, an air exhaust through hole 452b, and a hydrogen exhaust as in the separator 41. A through hole 454b, a cooling water supply through hole 456a, and a cooling water discharge through hole 456b are formed. As shown in FIG. 3B, a convex seal portion 459 is integrally provided around each of the through holes and the MEA portion 451. In FIG. A seal line SL indicated by a thin line is formed. In this embodiment, silicone rubber is used as the seal gasket 450.

  As shown in FIGS. 3B and 3C, the joining member 458A has a cylindrical shape. And as shown in FIG.3 (c), several joining member 458A is arranged in the peripheral part of MEA part 451 at equal intervals. Further, as illustrated in FIG. 3B, the joining member 458 </ b> A penetrates the MEA portion 451. And the seal gasket 450 is integrally formed in the outer periphery of the MEA part 451 in the state which covers the peripheral part of the MEA part 451, and the some joining member 458A arrange | positioned at the peripheral part. Here, as illustrated in FIG. 3B, the joining member 458 </ b> A is disposed at a position corresponding to the seal line SL formed by the seal portion 459 of the seal gasket 450. In this embodiment, the joining member 458A is a highly rigid material having a Young's modulus higher than the Young's modulus of the seal gasket 450, and uses an insulating material. For example, thermosetting resins such as epoxy resin, phenol, polystyrene, urea resin, and thermoplastic resins such as PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PEEK (polyether ether ketone), PES (polyether sulfone) Can be used. By using such an insulating material, even if the joining member 458a penetrates the catalyst electrodes 47a and 47c and the diffusion layers 48a and 48c, it is possible to prevent an electrical short circuit from occurring between them. it can.

  In this embodiment, silicone rubber is used, and the seal gasket 450 is integrally formed with the MEA portion 451 and the joining member 458A by injection molding. Specifically, the MEA part 451 through which the plurality of joining members 458A are penetrated is set in a mold and clamped. Subsequently, silicone rubber is injected into the cavity of the mold. Here, the cavity is formed in such a shape that silicone rubber covers the peripheral edge of the MEA portion 451 when silicone rubber is injected. Then, after the silicone rubber is cured, the mold is opened to obtain a seal gasket-integrated MEA 45A shown in FIG. When the seal gasket 450 is integrally formed with the MEA part 451 and the joining member 458A through such a process, the joining member 458A and the MEA part 451 are separated by a vulcanization (crosslinking) reaction when the silicone rubber is cured. Are bonded to the seal gasket 450, respectively.

As described above, according to the fuel cell stack 100 of the present embodiment, the bonding member 458A penetrates the MEA portion 451, and the portion protruding from the MEA portion 451 of the bonding member 458A is stuck in the seal gasket 450. Has been. That is, the MEA portion 451 and the seal gasket 450 are fixed with pins.
Therefore, even if the seal gasket 450 and the electrolyte membrane 46 of the MEA portion 451 are each contracted, the seal gasket 450 and the MEA portion 451 are joined by the joining member 458A. Limited. Therefore, it is possible to prevent the seal gasket 450 and the electrolyte membrane 46 that are bonded together by being integrally formed from peeling off.
Conventionally, in a seal gasket-integrated MEA, when the adhesion portion between the seal gasket and the electrolyte membrane is peeled off, hydrogen and air cross-leak, and hydrogen and oxygen in the air directly cause a chemical reaction. In some cases, the reaction efficiency at the electrode deteriorates and the power generation efficiency decreases. However, according to the fuel cell stack 100 of this embodiment, it is possible to prevent the seal gasket 450 and the electrolyte membrane 46 from being peeled off, and thus it is possible to prevent such a decrease in power generation efficiency. Moreover, it is possible to prevent abnormal combustion from occurring due to cross leak of hydrogen and air.

  Further, the joining member 458A is disposed inside the seal portion 459 so as to be along a seal line SL formed by the seal portion 459 protruding from the seal gasket 450. Here, since the joining member 458A is formed using a high-rigidity material having rigidity higher than that of the seal gasket 450, the pressing force with which the seal portion 459 presses the separator 41 is increased, and the sealing performance of the seal gasket 450 is improved. can do.

In the present embodiment, the joining member 458A is disposed at a position corresponding to the seal line SL, but is not limited to this position, and the MEA portion 451 and the seal gasket 450 may overlap each other. Good. Further, the number and shape of the joining members 458A are not limited to the present embodiment.
In this embodiment, silicone rubber is used as the seal gasket 450. However, the present invention is not limited to this, and other members having gas impermeability, elasticity, and heat resistance may be used.

B. Second embodiment:
The configuration of the fuel cell stack of the second embodiment is the same as that of the fuel cell stack 100 of the first embodiment except for the seal gasket-integrated MEA 45B. Further, the seal gasket-integrated MEA 45B in this embodiment is the same as the seal gasket-integrated MEA 45A in the first embodiment except for the joining member. Hereinafter, the configuration of the seal gasket-integrated MEA 45B in the present embodiment will be described.

  FIG. 4 is an explanatory view showing a seal gasket-integrated MEA 45B in the second embodiment. FIG. 4A shows a plan view of the seal gasket-integrated MEA 45B. FIG. 4B shows a cross-sectional view taken along the line AA in FIG. FIG. 4C shows a plan view of the joining member 458B.

  As shown in FIG. 4A, the seal gasket 450 of the seal gasket-integrated MEA 45B in this embodiment is cut off at the four corners of the separator 41 in the same manner as the seal gasket-integrated MEA 45A of the first embodiment. Has a missing shape. Further, the MEA portion 451, the air supply through hole 452a, the air discharge through hole 452b, the hydrogen supply through hole 454a, the hydrogen discharge through hole 454b, and the cooling water supply through hole in the seal gasket integrated MEA 45B. The hole 456a and the cooling water discharge through hole 456b are the same as the seal gasket-integrated MEA 45A in the first embodiment.

  As shown in FIGS. 4B and 4C, the joining member 458B includes a frame portion 458B1 having a substantially square frame shape having substantially the same dimensions as the MEA portion 451, and a columnar shape projecting from the frame portion 458B1. A plurality of electrolyte membrane penetrating portions 458B2. And each electrolyte-membrane penetration part 458B2 of the joining member 458B has penetrated the MEA part 451 similarly to the 1st Example. And the seal gasket 450 is integrally formed in the outer periphery of the MEA part 451 in the state which covers the peripheral part of the MEA part 451, and the joining member 458B arrange | positioned in the peripheral part. Further, the joining member 458 </ b> B is disposed at a position corresponding to the seal line SL formed by the seal portion 459 of the seal gasket 450.

  Note that the seal gasket-integrated MEA 45B of this embodiment is formed in the same process using the same material as the seal gasket-integrated MEA 45A of the first embodiment.

As described above, according to the fuel cell stack of this example, the electrolyte membrane penetration part 458B2 of the joining member 458B penetrates the MEA part 451. Then, similarly to the first embodiment, the seal gasket 450 is formed integrally with the MEA portion 451 in which the joining member 458B is disposed, thereby protruding from the electrolyte membrane 46 of the electrolyte membrane penetration portion 458B2 of the joining member 458B. The portion and the frame portion 458B1 are bonded to the seal gasket 450, respectively. Thereby, the seal gasket 450 and the MEA part 451 are joined by the joining member 458B.
Therefore, even if the seal gasket 450 and the electrolyte membrane 46 of the MEA portion 451 are each contracted, the seal gasket 450 and the MEA portion 451 are joined by the joining member 458A, so that the seal gasket is the same as in the first embodiment. The shrinkage of 450 and electrolyte membrane 46 is limited. Further, it is possible to prevent the seal gasket 450 and the electrolyte membrane 46 that are bonded together by being formed integrally. Therefore, as in the first embodiment, it is possible to prevent a decrease in power generation efficiency.
Similarly to the first embodiment, the joining member 458 </ b> B is disposed at a position corresponding to the seal line SL formed by the seal portion 459 protruding from the seal gasket 450. Therefore, the sealing performance of the seal gasket 450 can be improved as in the first embodiment.

  In the seal gasket-integrated MEA 45B of this embodiment, the seal gasket 450 is formed integrally with the MEA portion 451 by injection molding. Thus, when the seal gasket is formed integrally with the MEA part, the seal gasket and the MEA part have different shrinkage rates, and the seal gasket is made of soft silicone rubber having a low Young's modulus. Due to the shrinkage, the seal gasket may be deformed to wave. However, in the seal gasket-integrated MEA 45B of the present embodiment, the joining member 458B made of a highly rigid material having a bending elastic modulus (Young's modulus) larger than that of the seal gasket 450 has the frame portion 458B1 having a frame shape. Deformation of the seal gasket 450 can be suppressed.

C. Third embodiment:
The configuration of the fuel cell stack of the third embodiment is the same as that of the fuel cell stack 100 of the first embodiment except for the seal gasket-integrated MEA. Hereinafter, the seal gasket-integrated MEA 45C in this embodiment will be described.

  FIG. 5 is an explanatory view showing a seal gasket-integrated MEA 45C in the third embodiment. FIG. 5A shows a plan view of the seal gasket-integrated MEA 45C. FIG. 5B is a cross-sectional view taken along line AA in FIG. FIG. 5C is a cross-sectional view taken along line BB in FIG. 5A when the separators 41 and the seal gasket-integrated MEA 45C are alternately stacked.

  As shown in FIG. 5 (a), the seal gasket 450 of the seal gasket-integrated MEA 45C in this embodiment is similar to the seal gasket-integrated MEA in the first and second embodiments. The four corners of 41 are cut out. Further, in the seal gasket integrated MEA 45C, the air supply through hole 452a, the air discharge through hole 452b, the hydrogen supply through hole 454a, the hydrogen discharge through hole 454b, the cooling water supply through hole 456a, The water discharge through hole 456b is the same as the seal gasket-integrated MEA 45A in the embodiment of the first embodiment.

  On the other hand, as shown in FIG. 5 (b), the MEA portion 451C includes a cathode side catalyst electrode 47c and a cathode electrode on one surface of the electrolyte membrane 46, as in the first and second embodiments. This is a membrane electrode assembly in which the diffusion layer 48c is laminated in this order, and the anode side catalyst electrode 47a and the anode diffusion layer 48a are laminated in this order on the other surface. However, unlike the first and second embodiments, the MEA portion 451C extends to the end of the seal gasket 450. Further, the outer shape of the MEA portion 451C has a shape in which the four corners of the separator 41 are cut out, similarly to the seal gasket 450. Further, in the peripheral portion of the MEA portion 451C, an air supply through hole 452a, an air discharge through hole 452b, a hydrogen supply through hole 454a, a hydrogen discharge through hole 454b, and a cooling water supply are provided in the seal gasket 450. Through holes corresponding to the through hole 456a for cooling and the through hole 456b for discharging cooling water are formed.

  As shown in FIG. 5A, in the seal gasket-integrated MEA 45C, joining members 458C are disposed on four sides corresponding to the peripheral edge of the seal gasket 450, respectively. Then, as shown in FIGS. 5B and 5C, the joining member 458C includes a plurality of electrolyte membrane through portions 458C2 and a fitting portion having a recess 458C5 formed to be fitted to the outer peripheral portion of the separator 41. 458C3 and a connecting portion 458C4 that connects the electrolyte membrane penetrating portion 458C2 and the fitting portion 458C3. Here, each electrolyte membrane penetrating portion 458C2 has a columnar shape and penetrates the MEA portion 451C as in the second embodiment. Further, the fitting portion 458C3 is disposed so as to contact the end face of the seal gasket 450. As shown in FIG. 5A, the seal gasket 450 is formed integrally with the MEA portion 451C so as to surround the periphery of the through hole formed in the MEA portion 451C. That is, in the joining member 458 </ b> C, the plurality of electrolyte membrane penetrating portions 458 </ b> C <b> 2 and the connecting portion 458 </ b> C <b> 4 are included in the seal gasket 450, and the fitting portion 458 </ b> C <b> 3 is disposed outside the seal gasket 450.

  The seal gasket-integrated MEA 45C of this embodiment is formed in the same process using the same material as the seal gasket-integrated MEA 45A in the first embodiment.

As described above, according to the fuel cell stack of the third embodiment, the electrolyte membrane penetration part 458C2 of the joining member 458C penetrates the MEA part 451C. As in the first embodiment, the seal gasket 450 is formed integrally with the MEA portion 451C in which the joining member 458C is disposed, thereby protruding from the electrolyte membrane 46 of the electrolyte membrane penetration portion 458C2 of the joining member 458C. The portion and the connecting portion 458C4 are bonded to the seal gasket 450, respectively. Thereby, the seal gasket 450 and the MEA portion 451C are joined by the joining member 458C.
Therefore, as in the first and second embodiments, even when the seal gasket 450 and the electrolyte membrane 46 of the MEA portion 451C are about to contract, the seal gasket 450 and the MEA portion 451C are joined by the joining member 458C. Therefore, the shrinkage between the seal gasket 450 and the electrolyte membrane 46 is limited, and peeling between the seal gasket 450 and the electrolyte membrane 46 can be prevented. Therefore, similarly to the first embodiment and the second embodiment, it is possible to prevent a decrease in power generation efficiency.

  Furthermore, the joining member 458C of the present embodiment has a fitting portion 458C3 in which a concave portion 458C5 is formed so as to be fitted to the separator 41. And the fitting part 458C3 is arrange | positioned on the outer side of the seal gasket 450 so that the end surface of the seal gasket 450 may be contact | connected. Therefore, as shown in FIG. 5C, when the separator 41 and the seal gasket-integrated MEA 45C are alternately stacked, the concave portions 458C5 of the joining member 458C can be fitted into the four sides of the separator 41, respectively. Thus, the positioning of the separator 41 in the surface direction can be performed easily and accurately.

  Further, in the fuel cell having the conventional stack structure, when the seal gasket integrated MEA and the separator are alternately laminated, the seal portion of the seal gasket presses the separator from both sides of the separator. Here, for example, when a lateral shift occurs between the separator 41 and the seal gasket-integrated MEA due to the reaction gas pressure during operation of the fuel cell stack, the seal line of the seal portion that presses one separator from both sides is displaced. End up. Thereby, the separator may be inclined or the separator may be cracked or deformed. However, according to the fuel cell stack of this embodiment, when the seal gasket-integrated MEA 45C and the separator 41 are alternately stacked, the recesses 458C5 of the joining member 458C are connected to the separator 41 as shown in FIG. By fitting each of the two sides, the positions in the surface direction of the separator 41 and the seal gasket-integrated MEA 45C are fixed, and the occurrence of lateral displacement can be suppressed. Accordingly, the shift of the seal line SL of the seal portion 459 that presses the single separator 41 from both sides is suppressed, and the separator 41 can be prevented from being tilted or cracked or deformed.

D. Fourth embodiment:
The configuration of the fuel cell stack of the fourth embodiment is the same as that of the fuel cell stack of the first embodiment except for the seal gasket-integrated MEA 45D. Hereinafter, the configuration of the seal gasket-integrated MEA 45D in the present embodiment will be described.

  FIG. 6 is an explanatory view showing a seal gasket-integrated MEA 45D in the fourth embodiment. FIG. 6A shows a plan view of the seal gasket-integrated MEA 45D. FIG. 6B is a cross-sectional view taken along the line AA in FIG. FIG. 6C shows a plan view of the joining member 458D.

  As shown in FIG. 6A, the seal gasket 450 of the seal gasket-integrated MEA 45D in this embodiment is cut off at the four corners of the separator 41 in the same manner as the seal gasket-integrated MEA 45A of the first embodiment. Has a missing shape. Further, the MEA portion 451, the air supply through hole 452a, the air discharge through hole 452b, the hydrogen supply through hole 454a, the hydrogen discharge through hole 454b, and the cooling water supply through in the seal gasket integrated MEA 45D. The hole 456a and the cooling water discharge through hole 456b are the same as the seal gasket-integrated MEA 45A in the first embodiment.

  As shown in FIGS. 6B and 6C, the joining member 458D has a frame portion 458D1 having a substantially square frame shape having substantially the same dimensions as the MEA portion 451, and a columnar shape protruding from the frame portion 458D1. A plurality of electrolyte membrane penetrating portions 458D2, a fitting portion 458D3 having a recess 458D5 formed to be fitted to the separator 41, and a connecting portion 458D4 for connecting the frame portion 458D1 and the fitting portion 458D3. ing. And each electrolyte membrane penetration part 458D2 has each penetrated the MEA part 451 similarly to the 3rd Example. The seal gasket 450 is integrally formed on the outer periphery of the MEA portion 451 so as to cover the peripheral portion of the MEA portion 451 and a part of the joining member 458D disposed on the peripheral portion. Further, the fitting portion 458D3 is disposed so as to be in contact with the end face of the seal gasket 450.

  Note that the seal gasket-integrated MEA 45D of this embodiment is formed in the same process using the same material as the seal gasket-integrated MEA 45A of the first embodiment.

As described above, according to the fuel cell stack of the fourth embodiment, the electrolyte membrane penetration part 458D2 of the joining member 458D penetrates the MEA part 451. Similarly to the first embodiment, the seal gasket 450 is formed integrally with the MEA portion 451 in which the joining member 458D is disposed, thereby protruding from the electrolyte membrane 46 of the electrolyte membrane penetration portion 458D2 of the joining member 458D. The portion, the frame portion 458D1, and the connecting portion 458D4 are bonded to the seal gasket 450, respectively. Thereby, the seal gasket 450 and the MEA part 451 are joined by the joining member 458D.
Therefore, even if the seal gasket 450 and the electrolyte membrane 46 of the MEA portion 451 are each contracted, the seal gasket 450 and the MEA portion 451 are joined by the joining member 458D, and thus the first to third embodiments. Similarly to the example, the shrinkage between the seal gasket 450 and the electrolyte membrane 46 is limited, and the peeling between the seal gasket 450 and the electrolyte membrane 46 can be prevented.

  Further, the bonding member 458D of the present embodiment has a recess 458D5 that can be fitted to the separator 41. Therefore, as in the third embodiment, when the separator 41 and the seal gasket-integrated MEA 45A are stacked, the separator 41 can be easily and accurately positioned in the surface direction. Similarly to the third embodiment, when the fuel cell stack is operated, it is possible to suppress the occurrence of a lateral shift between the separator 41 and the seal gasket-integrated MEA 45D. Can be prevented from cracking or deforming.

  Further, when the joining member 458D is used, in the seal gasket-integrated MEA, even if the MEA has a shape that does not reach the end of the seal gasket (the same shape as in the present embodiment), the same as in the third embodiment. In addition, separation of the seal gasket 450 and the electrolyte membrane 46 can be prevented, and cracking and deformation of the separator 41 can be prevented. Therefore, since an expensive electrolyte membrane can be formed small, cost can be reduced.

E. Variation:
As mentioned above, although several embodiment of this invention was described, this invention is not limited to such embodiment at all, and implementation in various aspects is possible within the range which does not deviate from the summary. It is.

  In the embodiment described above, the MEA is configured by laminating the electrolyte membrane 46 having the same outer shape, the anode side catalyst electrode 47a, the cathode side catalyst electrode 47c, the anode diffusion layer 48a, and the cathode diffusion layer 48c. However, it is not limited to this. For example, when only the electrolyte membrane 46 is formed large and another membrane is laminated on the electrolyte membrane 46, the periphery of the electrolyte membrane 46 is exposed outside the outer circumference of the other membrane. Good. In this case, the seal gasket-integrated MEA can be formed such that only the exposed peripheral edge of the electrolyte membrane 46 is sandwiched between the seal gaskets 450. In this case, for example, when the seal gasket is formed integrally with the MEA by injection molding, the catalyst electrodes 47a and 47c are not covered with silicone rubber for forming the seal gasket 450. It is possible to prevent the catalyst electrodes 47a and 47c from being deformed or damaged by heat.

  In the first and second embodiments described above, an insulating material is used as the joining member. However, by using the following configuration, a conductive material is used. Also good. That is, as in the first and second embodiments, in the configuration where the joining member and the separator do not contact (that is, does not have a fitting portion), as described above, only the electrolyte membrane 46 is used as the MEA. The MEA is used such that the periphery of the electrolyte membrane 46 is exposed outside the outer periphery of the other membrane, and only the periphery of the electrolyte membrane 46 is penetrated by the bonding member. In such a configuration, since the joining member and the separator do not come into contact with each other, even when a conductive material is used as the joining member, the electrolyte membrane 46 and the separator are not electrically short-circuited. Since the member does not penetrate the catalyst electrodes 47a and 47c, there is no short circuit between the electrodes.

  In the third and fourth embodiments described above, an insulating material is used as the joining member, but the following configuration may be used. For example, among the joining members, the electrolyte membrane penetrating portion is formed of an insulating material, and the fitting portion, the connecting portion, the frame portion, and the like are formed of a conductive material. If the joining member has such a configuration, even if the electrolyte membrane penetrating portion penetrates the catalyst electrodes 47a and 47c, there is no electrical short-circuit between the electrodes, and from the separator to the fitting portion. Even if current flows, there is no electrical short between the electrodes.

  Further, in the above-described embodiment, the separator is configured by three plates of the cathode facing plate, the intermediate plate, and the anode facing plate, but is not limited thereto. For example, a separator formed by processing one block-like member such as carbon may be used.

1 is a perspective view showing a schematic configuration of a fuel cell stack 100 as a first embodiment of the present invention. FIG. 4 is a plan view of components of the separator 41 and the separator 41. It is explanatory drawing which shows seal gasket integrated MEA45A. It is explanatory drawing which shows the seal gasket integrated MEA45B in a 2nd Example. It is explanatory drawing which shows the seal gasket integrated type MEA45C in a 3rd Example. It is explanatory drawing which shows seal gasket integrated type MEA45D in a 4th Example.

Explanation of symbols

10 ... End plate 20 ... Insulating plate 30 ... Current collector plate 40 ... Fuel cell module 41 ... Separator 42 ... Cathode facing plate 43 ... Intermediate plate 44 ... Anode facing Plate 46 ... Electrolyte membrane 47a ... Anode side catalyst electrode 47c ... Cathode side catalyst electrode 48a ... Anode diffusion layer 48c ... Cathode diffusion layer 50 ... Current collector plate 60 ... Insulating plate 70 ... End plate 80 ... Tension plate 82 ... Bolt 100 ... Fuel cell stack 422a, 432a, 442a, 452a ... Air supply through hole 422b, 432b, 442b, 452b ... . Air exhaust through hole 422i ... Air supply port 422o ... Air exhaust port 424a, 434a, 444a, 454a ... Hydrogen supply through hole 424b, 434b, 444b, 454b ... Hydrogen exhaust through hole 426a, 44 6a, 456a ... Cooling water supply through hole 426b, 446b, 456b ... Cooling water discharge through hole 432c ... Air supply flow path forming part 432d ... Air discharge flow path forming part 432e. .. Hydrogen supply flow path forming part 432f ... Hydrogen discharge flow path forming part 436 ... Cooling water flow path forming through hole 444i ... Hydrogen supply port 444o ... Hydrogen discharge port 45A, 45B, 45C , 45D ... MEA with seal gasket
450 ... Seal gasket 458A, 458B, 458C, 458D ... Joining member 458B1, 458D1 ... Frame part 458B2, 458C2, 458D2 ... Electrolyte membrane penetration part 458C3, 458D3 ... Fitting part 458C4, 458D4 ... Connecting part 458C5,458D5 ... Recess

Claims (7)

A fuel cell having a stack structure in which at least a polymer electrolyte membrane and MEA (Membrance Electrode Assembly) having electrodes formed on both sides of the polymer electrolyte membrane are stacked with a separator interposed therebetween.
A joining member having a plurality of electrolyte membrane penetrating portions penetrating at least a part of the peripheral portion of the polymer electrolyte membrane;
A seal member formed integrally with the MEA so as to cover at least a part of the joining member and the peripheral edge of the polymer electrolyte membrane;
A fuel cell comprising: The fuel cell according to claim 1, wherein
The joining member is
It further comprises a frame part formed so as to go around in a frame shape,
The electrolyte membrane penetration part is
A fuel cell, wherein the fuel cell protrudes from the frame portion. The fuel cell according to claim 2, wherein
The joining member is
The fuel cell according to claim 1, wherein at least the frame portion is made of a highly rigid material having higher rigidity than the seal member. The fuel cell according to claim 2 or claim 3, wherein
The sealing member is
A plurality of through holes forming a manifold through which fuel gas, oxidant gas, or cooling medium can circulate when a plurality of the MEAs are stacked via the separator;
The frame part is
The fuel cell, wherein the through hole is formed so as to be positioned on an outer periphery of the frame portion. The fuel cell according to any one of claims 2 to 4, wherein
At least the frame part
A fuel cell, which is enclosed in the seal member. The fuel cell according to any one of claims 1 to 5, wherein
The electrolyte membrane penetration part is
A fuel cell comprising at least the polymer electrolyte membrane and the electrode, and made of an insulating material. The fuel cell according to any one of claims 1 to 6, wherein
The joining member is
When the MEA is laminated with the separator interposed, the MEA further includes a fitting portion that fits at least a part of the peripheral edge of the separator,
The fuel cell, wherein the electrolyte membrane penetrating part and the fitting part are insulated.

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