JP6748849B2 - Fuel cell membrane electrode assembly and fuel cell - Google Patents

Description

The present invention relates to a fuel cell, particularly a membrane electrode assembly used in a polymer electrolyte fuel cell, and a fuel cell using the same.

A fuel cell has a structure in which a catalyst layer is joined to an electrolyte membrane that causes a power generation reaction, and a catalyst cell is sandwiched by separators to form a single cell module, and a required number of modules are stacked.

The electrolyte membrane is mainly fixed to a frame member made of resin. With this frame member, it is possible to improve the handleability when sandwiching and assembling with the separator and to reduce the amount of the electrolyte material used in the non-power generation portion.

In order to operate a fuel cell, it is necessary to supply fuel gas (hydrogen gas) to one of the electrodes formed on both sides of the electrolyte membrane and oxygen (air) to the other, and one gas to the other. When it flows in, a normal electrochemical reaction is not performed, and sufficient power generation characteristics cannot be obtained. Therefore, the portion where the electrolyte membrane is fixed to the frame body must have gas sealing properties.

As a conventional method for fixing an electrolyte membrane to a frame member, there is one in which an electrolyte membrane is welded to a resin frame member using ultrasonic waves (see, for example, Patent Document 1).

Hereinafter, the membrane electrode assembly of the conventional fuel cell disclosed in Patent Document 1 will be described.

FIG. 2 is a cross-sectional view of a single cell module in which a membrane electrode assembly of a conventional fuel cell disclosed in Patent Document 1 is sandwiched by separators. FIG. 3 is a plan view of a membrane electrode assembly of the conventional fuel cell.

As shown in FIG. 2, in a conventional membrane electrode assembly 11 of a fuel cell, an end portion of the electrolyte membrane 2 is provided with a resin-made frame-shaped first frame member 51 and a resin-made frame-shaped second frame. The first frame member 51 and the second frame member 52 are sandwiched between the member 52 and the electrolyte membrane 2, and the first frame member 51 and the second frame member 52 are joined to each other at the fusion-welded portion 8 to form the first frame member 51 and the second frame member 52. The boundary portion and the fusion-welded portion 8 are covered with the third frame member 53 from the outside of the second frame member 52.

By disposing the gas diffusion layers 4 for uniformly distributing the fuel gas and the oxidant gas to the catalyst on both surfaces of the membrane electrode assembly 11, and sandwiching them with the separator 6 with the seal member 7 having the gas flow path 61. , The single cell module 1 is configured. The gas diffusion layer 4 rides on the first frame member 51 and the second frame member 52 and fills the space with the separator 6.

When there is a space between the separator 6 and the first frame member 51 and the second frame member 52, the fuel gas and the oxidant gas do not pass through the gas flow path 61, and the first frame member 51 Also, the fuel gas and the oxidant gas do not spread to the power generation region 12 because they pass through the space between the second frame member 52 and the separator 6, and sufficient power generation performance cannot be obtained.

By filling the gas diffusion layer 4 between the first frame member 51 and the second frame member 52 and the separator 6, the fuel gas and the oxidant gas will pass through the gas flow path 61, It is possible to obtain a predetermined power generation performance.

In addition, the thickness of the region of the gas diffusion layer 4 located between the first frame member 51 and the second frame member 52 and the separator 6 is set to the thickness of the first frame member 51 and the second frame member 52 and the separator. When the membrane electrode assembly 11 is sandwiched by the separators 6, the gas diffusion layer 4 is compressed and the first frame member 51 and the second frame member 52 are made thicker than the interval of 6 so that the electrolyte membrane 2 is formed. Can be adhered to.

Further, by bringing the first frame member 51 and the second frame member 52 into close contact with the electrolyte membrane 2, between the electrolyte membrane 2 and the first frame member 51 and between the electrolyte membrane 2 and the second frame member 52, The possibility that the fuel gas and the oxidant gas may enter can be reduced, the gas barrier property can be improved, and the deterioration of the electrolyte membrane 2 due to the fuel gas and the oxidant gas can be suppressed, and the performance of the fuel cell can be ensured for a long time. Can be done.

The catalyst layer electrodes 3 are uniformly formed on both surfaces of the electrolyte membrane 2 except for the ends. A part of the first frame member 51 and the second frame member 52 covers the end portion of the catalyst layer electrode 3. By doing so, it is possible to reduce the exposure of the oxidant gas to the region of the electrolyte membrane 2 where the catalyst layer electrode 3 is not formed, and it is possible to suppress the deterioration of the electrolyte membrane due to the oxidant gas. Become.

When the single cell module 1 is formed, the seal member 7 provided on the separator 6 is arranged on the power generation region side with respect to the fusion welding portion 8 formed on the membrane electrode assembly 11, and the region of the catalyst layer electrode 3 is formed. It is placed outside.

In the case of the single cell module 1, the seal member 7 provided on the separator 6 comes into contact with the first frame member 51 and the second frame member 52 and is compressed. The reaction force of the seal member 7 is generated by the compression, and the seal member 7 and the first frame member 51 and the second frame member 52, the first frame member 51 and the second frame member 52, and the electrolyte membrane 2 are separated from each other. The adhesion is improved and the gas barrier property can be secured.

The catalyst layer electrode 3 has a porous structure because the fuel gas and the air gas diffuse to cause a power generation reaction. Therefore, when the catalyst layer electrode 3 and the seal member contact portion 71 overlap with each other, the porous portion of the catalyst layer electrode 3 cannot be shielded only by the reaction force of the seal member 7, which causes a gas leak.

The seal member 7 provided on the side of the first frame member 51 and the seal member 7 provided on the side of the second frame member 52 are disposed at opposite positions with the membrane electrode assembly 11 interposed therebetween, and are provided at both electrodes. Both of the sealing members 7 are arranged so as not to overlap with the catalyst layer electrode 3. However, if at least one of the sealing members 7 does not overlap the catalyst layer electrode 3, the side of the sealing member 7 that does not cover the catalyst layer electrode 3 is sufficient. A good gas barrier property can be secured.

When the seal members 7 are arranged at the positions facing each other, the reaction force of the seal member 7 applied to the membrane electrode assembly 11 faces each other, and the membrane electrode assembly 11 is not stressed. If the electrode 3 is not applied, the gas barrier property may be more secured.

By providing the seal member 7 closer to the power generation region 12 than the melt-welded portion 8, when the melt-welded portion 8 is formed, the deformed portion of the electrolyte membrane 2 due to heat and vibration during ultrasonic welding causes the fuel gas and the oxidant. Exposure to gas or moisture can be suppressed, gas leak can be reduced, and power generation performance of the fuel cell can be maintained. Further, it is possible to reduce swelling and contraction due to absorption of water, prevent concentration of mechanical stress, prevent destruction of the electrolyte membrane structure, and maintain fuel cell performance for a long period of time.

As shown in FIG. 3, the membrane electrode assembly 11 includes a first frame member 51, a second frame member 52, and a third frame member 53 so as to surround the four sides of the electrolyte membrane 2, In the vicinity of the electrolyte membrane end portion 21 of the membrane 2, the melt-welded portions 8 are provided at a predetermined melt-welded portion interval 82.

The first frame member 51 is provided with an opening serving as the power generation region 12 at the center. Since the openings provided in the first frame member 51 and the second frame member 52 have the same size, the area that can be used for the power generation area 12 becomes large and the utilization rate of the electrolyte membrane is good.

The electrolyte membrane 2 is larger than the power generation region 12 and has a size that does not protrude from the first frame member 51 and the second frame member 52 when sandwiched between the first frame member 51 and the second frame member 52. That's it.

The first frame member 51 to the third frame member 53 are provided with a manifold 9 that supplies the fuel gas or the oxidant gas necessary for the power generation reaction of the fuel cell.

The seal member 7 is arranged on the separator 6 so that the seal member contact portion 71 surrounds the entire region of the power generation region 12 and the gasket 9.

In the membrane electrode assembly 11, the fusion welding portion 8 of the first frame member 51 and the second frame member 52 is formed by ultrasonic welding via the electrolyte membrane 2. The second frame member 52 is also provided with an opening serving as the power generation region 12 in the central portion.

In forming the fusion-welded portion 8 of the first frame member 51 and the second frame member 52 through the electrolyte membrane 2 using ultrasonic welding, the first frame material, the second frame material, and the electrolyte It is possible to form the melt-welded portion 8 in which the films are mixed.

By forming the melt-welded portion 8 in which the frame material and the electrolyte membrane material are mixed, the fixability of the first frame member 51 and the second frame member 52 and the electrolyte membrane 2 can be further improved, and the wet and dry dimensions can be improved. The concentration of stress on the electrolyte membrane 2 due to the change can be avoided, and the long-term durability of the electrolyte membrane 2 can be improved.

The third frame member 53 covers the boundary surface between the first frame member 51 and the second frame member 52 and the processing mark of the fusion-welded portion 8.

FIG. 4 is an explanatory view showing a process of assembling a membrane electrode assembly of a conventional fuel cell. First, the first frame member 51 and the second frame member 52 are manufactured in advance by injection molding, and the electrolyte membrane 2 coated with the catalyst layer electrode 3 is arranged on the first frame member 51, and then the second frame member 51 is formed. The frame member 52 is arranged.

Next, the ultrasonic horn 81 is brought into contact with a predetermined position from the outside of the second frame member 52 to form the fusion-welded portion 8. Next, the electrolyte membrane 2 integrated with the first frame member 51 and the second frame member 52 is placed in the mold of the injection molding machine to form the third frame member 53.

The fusion welding portion 8 is formed in a spot shape by using ultrasonic bonding. When the spot-shaped melt-welded portion 8 is used, the assembly time of the membrane electrode assembly 11 is shortened and the productivity can be improved.

The ultrasonic processing tool to be brought into contact with the second frame member 52 had a tip of φ0.5 mm. When ultrasonically joining the first frame member 51 and the second frame member 52, the joining processing condition is an ultrasonic joining machine (ΣG620S) manufactured by Seidensha Kogyo Co., Ltd., at a frequency of 28.5 kHz. The amplitude is 40 μm, the pressing force is 30 N, and the processing time is 0.25 seconds.

The distance between the fusion-welded portion 8 and the seal member 7 was about 2 mm. Although the amount of the electrolyte membrane in the region that does not contribute to power generation can be reduced by further narrowing the distance between the fusion-welded portion 8 and the seal member 7, the electrolyte membrane 2 around the processed portion can be reduced due to heat and vibration during ultrasonic bonding. In order to deform the structure, the deformed region of the electrolyte membrane 2 is arranged so as not to come inward of the sealing member 7 with respect to the power generation surface.

A third frame member 53 is formed by integrally forming a frame member that covers the boundary surface between the first frame member 51 and the second frame member 52 and a frame member that covers the processing mark of the fusion-welded portion 8. When integrally formed in this way, the rigidity of the membrane electrode assembly 11 is further improved, and the handling property and the like are improved.

As shown in FIG. 4, since the third frame member 53 is injection-molded directly on the first frame member 51 and the second frame member 52, the first frame member 51 and the second frame member 52 are When the same resin material is used for the third frame member 53, the bonding force between the frame members is increased, the integrity of the membrane electrode assembly 11 is improved, and the handleability is improved.

In addition, a thermoplastic resin is used as the material of the frame portion of the first frame member 51 and the second frame member 52, and the first frame member 51 and the second frame member 52 are particularly suitable for the power generation environment of the fuel cell. It is more preferable to use a material such as modified PPE, modified PPE or PPS because it is exposed.

Since the electrolyte membrane 2 having the isotropic characteristics in the vertical direction and the horizontal direction is used as the electrolyte membrane 2, the melt-welded portion intervals 82 are set to be equal over the entire circumference of the power generation region. In the case of forming, the electrolyte membrane 2 can equalize the concentration of stress on the melt-welded portion 8 due to dry shrinkage or wet expansion.

Patent No. 5575345

However, in the conventional membrane electrode assembly 11 disclosed in Patent Document 1, when welding the first frame member 51 and the second frame member 52 with the ultrasonic horn 81, as shown in FIG. The molten resin of the second frame member 52 penetrates the electrolyte membrane 2 and is extruded between the first frame member 51 and the second frame member 52, and while the second frame member 52 is being lifted, around the ultrasonic horn 81. Accumulate.

As it is, the ultrasonic horn 81 penetrates through the second frame member 52, and while melting, the ultrasonic horn 81 compatibilizes with the resin accumulated around the ultrasonic horn 81 and solidifies, thereby holding the outer peripheral portion of the electrolyte membrane 2. The gap between the first frame member 51 and the second frame member 52 widens, and wrinkles occur in the electrolyte membrane 2 and cross leak occurs.

In order to solve the above-mentioned conventional problems, the membrane electrode assembly of the fuel cell of the present invention has a surface on at least one of the electrolyte membrane sides of a pair of resin frame members that sandwich the outer peripheral portion of the electrolyte membrane. The recessed portion is provided to accommodate the welded portion in which the resin material forming the frame member and the material of the electrolyte membrane are mixed.

As a result, the interval between the pair of resin frame members that sandwich the outer peripheral portion of the electrolyte membrane does not widen, and wrinkles do not occur in the portion that sandwiches the electrolyte membrane, preventing cross leak of fuel gas and oxidant gas. Moreover, since the utilization efficiency of the fuel gas and the oxidizing gas can be further enhanced, it becomes possible to produce a single cell module useful as a fuel cell.

According to the present invention, the distance between the pair of resin frame members that sandwich the outer peripheral portion of the electrolyte membrane does not widen, and wrinkles do not occur in the portion that sandwiches the electrolyte membrane. Since leakage can be prevented and the utilization efficiency of the fuel gas and the oxidizing gas can be increased, it becomes possible to produce a single cell module useful as a fuel cell.

An explanatory view showing a method of fixing an electrolyte membrane in a membrane electrode assembly of a fuel cell of an embodiment of the invention with a pair of resin frames. Sectional view of a single cell module in which a membrane electrode assembly of a conventional fuel cell disclosed in Patent Document 1 is sandwiched by separators. Plan view of a membrane electrode assembly of the conventional fuel cell Explanatory drawing which shows the assembly process of the membrane electrode assembly of the same conventional fuel cell Explanatory drawing showing a method for fixing an electrolyte membrane in a membrane electrode assembly of a conventional fuel cell with a pair of resin frames

A first invention is a membrane electrode assembly for a fuel cell in which an outer peripheral portion of an electrolyte membrane is sandwiched between a first frame member made of resin and a second frame member made of resin, and the membrane electrode assembly comprises: On at least one of the surfaces of the second frame member on the side of the electrolyte membrane, a concave portion capable of accommodating a welded portion in which the resin material forming the frame member and the material of the electrolyte membrane are mixed is provided.

Thus, for example, when the first frame member made of resin, the second frame member made of resin, and the outer peripheral portion of the electrolyte membrane are welded using the ultrasonic horn, the ultrasonic horn is pressed against the frame member. At this time, a mixture of the resin of the frame member and the material of the electrolyte membrane, which has been melted by heat or vibration, flows into the recess, and the gap between the first frame member and the second frame member does not widen.

Therefore, since wrinkles do not occur in the portion sandwiching the electrolyte membrane, cross leak of the fuel gas and the oxidant gas can be prevented, and the utilization efficiency of the fuel gas and the oxidant gas can be improved.

In a second aspect of the present invention, in particular, in the first aspect, a hole that penetrates the electrolyte membrane and reaches the other frame member is formed in one surface of the first frame member and the second frame member of the electrolyte membrane. Concavely provided so as to be scattered on the outer periphery, in the vicinity of the through hole penetrating the electrolyte membrane, the welded portion is present, and the recessed portion has an inner diameter larger than the inner diameter of the hole and more than the volume of the hole. It is recessed with a large volume.

Thereby, the welded portion in which the resin material forming the frame member and the material of the electrolyte membrane are mixed can be accommodated in the recess.

A third aspect of the invention is that the first frame member and the second frame member in the first or second aspect are made of the same resin material.

Thereby, the bonding force between the frame members is increased, the integrity of the membrane electrode assembly is improved, and the handleability is improved.

A fourth aspect of the invention is to block the hole with a third frame member in any of the first to third aspects.

A third frame member is formed by integrally forming a frame that covers the boundary surface between the first frame member and the second frame member and a frame that covers the processing mark of the fusion-welded portion.

In this state, the frame that covers the boundary surface between the first frame member and the second frame member and the frame that covers the processing mark of the fusion-welded portion may be formed as separate members. The rigidity of the electrode assembly is further improved, and the handling property is improved.

A fifth aspect of the invention is the frame according to the fourth aspect, wherein the third frame member is the one of the first frame member and the second frame member in which at least the hole is recessed in the surface. It is the same resin material as the member.

As a result, when the same resin material is used in injection molding the third frame member directly into the first frame member and the second frame member, the bonding force between the frame members is increased and the membrane electrode bonding is performed. Improves body integrity and handling.

The sixth invention is, in any one of the first to fifth inventions, in which the welding portion is formed by using an ultrasonic horn.

With this configuration, the electrolyte membrane is fixed to the frame at the fusion-bonded portion, and the gas-sealing property is ensured by the seal member provided on the power generation region side of the welded portion. By providing the sealing member closer to the power generation region than the fusion-bonded portion where gas leakage is likely to occur, the gas sealing property can be secured without the gas reaching the fusion-bonded portion.

A seventh invention is a fuel cell in which the membrane electrode assembly of the fuel cell according to any one of the first to sixth inventions is sandwiched between a pair of separators.

Thereby, the fuel gas and the oxidant gas can be evenly distributed over the catalyst.

The eighth invention is a fuel cell in which a plurality of the fuel cells of the seventh invention are stacked.

Thus, by stacking a plurality of fuel cells and fastening them with a predetermined load from both sides of the current collector plate and the end plate, current can be taken out during power generation.

Embodiments of the present invention will be described below with reference to the drawings, regarding parts different from the conventional example.

(Embodiment 1)
FIG. 1 is an explanatory diagram showing a method of fixing an electrolyte membrane in a membrane electrode assembly of a fuel cell according to Embodiment 1 of the present invention with a first frame and a second frame.

In the present embodiment, the seal member 7 provided on the first frame member 51 side and the seal member 7 provided on the second frame member 52 side are arranged at positions facing each other with the membrane electrode assembly 11 interposed therebetween. The seal members 7 provided on both electrodes are arranged so as not to overlap the catalyst layer electrode 3, but it is not necessary to dispose the seal members 7 at positions facing each other and a sufficient reaction force of the seal member 7 cannot be obtained. Good.

Further, if at least one of the seal members 7 does not cover the catalyst layer electrode 3, sufficient gas barrier properties may be secured on the side of the seal member 7 that does not cover the catalyst layer electrode 3.

In the present embodiment, when the sealing member 7 is provided on the power generation region 12 side of the fusion welding portion 8, when the fusion welding portion 8 is formed, a deformed portion of the electrolyte membrane 2 due to heat and vibration during ultrasonic welding is generated. Exposure to fuel gas, oxidant gas, and water can be suppressed, gas leak can be reduced, and power generation performance of the fuel cell can be maintained.

Further, it is possible to reduce swelling and shrinkage due to adsorption of water, prevent concentration of mechanical stress, prevent destruction of the electrolyte membrane structure, and maintain fuel cell performance for a long period of time.

In the present embodiment, the first frame member 51 is provided with an opening serving as the power generation region 12 at the center. The openings provided in the first frame member 51 and the second frame member 52 may have different sizes, and when the openings have the same size, the area that can be used for the power generation area 12 becomes large and the utilization rate of the electrolyte membrane 2 is increased. Good.

The electrolyte membrane 2 is larger than the power generation region 12 and has a size that does not protrude from the first frame member 51 and the second frame member 52 when sandwiched between the first frame member 51 and the second frame member 52. All right.

In the present embodiment, the fusion-welded portion 8 of the first frame member 51 and the second frame member 52 is formed by ultrasonic welding via the electrolyte membrane 2. The second frame member 52 is also provided with an opening serving as the power generation region 12 in the central portion. It is possible to form the melt-welded portion 8 in which the electrolyte membrane 2 using ultrasonic welding is mixed.

By forming the melt-welded portion 8 in which the material of the frame member and the material of the electrolyte membrane 2 are mixed, the fixability of the electrolyte membrane 2 with the first frame member 51 and the second frame member 52 can be further improved. It is possible to avoid concentration of stress on the electrolyte membrane 2 due to changes in dry and wet dimensions, and improve the long-term durability of the electrolyte membrane 2.

In the present embodiment, the third frame member 53 is formed so as to cover the boundary surface between the first frame member 51 and the second frame member 52 and the processing mark of the fusion-welded portion 8, and the membrane electrode assembly 11 is formed. Assemble.

The first frame member 51 and the second frame member 52 are manufactured in advance by injection molding, and the electrolyte membrane 2 coated with the catalyst layer electrode 3 is arranged on the first frame member 51, and then the second frame member is formed. 52 is arranged.

The ultrasonic horn 81 is brought into contact with a predetermined position from the outside of the second frame member 52 to form the melt-welded portion 8. The electrolyte membrane 2 integrated with the first frame member 51 and the second frame member 52 is placed in a mold of an injection molding machine to form a third frame member 53.

In the present embodiment, spot-shaped melt-welded portion 8 is formed. In this embodiment, ultrasonic welding is used to form the fusion-welded portion 8. For ultrasonic bonding, an ultrasonic bonding machine (ΣG620S) manufactured by Seidensha Kogyo Co., Ltd. was used.

The ultrasonic processing tool brought into contact with the frame member had a tip of φ0.5 mm. As the joining processing conditions for ultrasonically joining the frame members, good joining was obtained at a frequency of 28.5 kHz, an amplitude of 40 μm, a pressing force of 30 N, and a working time of 0.25 seconds.

In the present embodiment, the distance between the fusion-welded portion 8 and the seal member 7 is about 2 mm. Although the amount of the electrolyte membrane in the region that does not contribute to power generation can be reduced by further narrowing the distance between the fusion-welded portion 8 and the seal member 7, the electrolyte membrane 2 around the processed portion can be reduced due to heat and vibration during ultrasonic bonding. Therefore, it is preferable to dispose the deformed region of the electrolyte membrane 2 so as not to come inward of the sealing member 7 with respect to the power generation surface.

In the present embodiment, the third frame member 53 is formed by integrally forming the frame member that covers the boundary surface between the first frame member 51 and the second frame member 52 and the frame member that covers the processing mark of the fusion-welded portion 8. doing. In this state, the frame member that covers the boundary surface between the first frame member 51 and the second frame member 52 and the frame member that covers the processing mark of the fusion welded portion 8 may be formed as separate members, but they may be formed integrally. When formed, the rigidity of the membrane electrode assembly 11 is further improved, and the handling property and the like are improved.

In the present embodiment, a hole that penetrates the electrolyte membrane 2 and reaches the other first frame member 51 is formed on the surface of one of the first frame member 51 and the second frame member 52 of the second frame member 52. The electrolyte membrane 2 is recessed so as to be scattered on the outer periphery thereof, and the outer periphery of the electrolyte membrane 2 is sandwiched by a resin frame having a recess on the electrolyte membrane 2 side of the contact portion of the ultrasonic horn 81. Fix it.

Further, the concave portion provided in the portion of the first frame member 51 and the second frame member 52 on the electrolyte membrane 2 side of the first frame member 51 is larger than the inner diameter of the hole formed by the ultrasonic horn 81. The welded portion does not protrude to the outer peripheral side of the recess when viewed from a direction perpendicular to the main surface of the electrolyte membrane 2 having an inner diameter and a volume larger than the volume of the hole.

As a result, when the ultrasonic horn 81 is brought into contact with the resin, the resin melted by heat or vibration is contained in the concave portion of the first frame member 51, and the distance between the first frame member 51 and the second frame member 52 is prevented from widening. .. The size of the recess is appropriately determined depending on the ultrasonic horn 81 and the resin and is not particularly limited. For example, the short side is 1.5 mm, the long side is 2.3 mm, and the thickness is about 0.1 mm.

In the present embodiment, the first frame member 51, the second frame member 52, and the third frame member 53 are made of the same resin material. Since the third frame member 53 is directly injection-molded on the first frame member 51 and the second frame member 52, when the same resin material is used, the bonding force between the frames is increased, and the membrane electrode assembly is obtained. The unity of 11 is improved and the handling is improved.

Further, in the present embodiment, a thermoplastic resin is used as the frame material of the first frame member 51 and the second frame member 52, and in particular, the first frame member 51 and the second frame member 52 are made of fuel. It is more preferable to use a material such as modified PPE, modified PPE or PPS because it is exposed to the power generation environment of the battery.

In the present embodiment, the spot-shaped fusion-welded portion 8 is formed, but a fusion-bonded portion on the line may be formed or may not be intermittent.

When the spot-shaped melt-welded portion 8 is used, the assembly time of the membrane electrode assembly 11 is shortened, and the productivity can be improved. Further, when the continuous or intermittent melt-welded portion 8 is formed, the fixing strength of the electrolyte membrane 2 to the frame member can be improved.

The shape of the fusion welding portion 8 may be selected as an optimum shape depending on the assembly environment, the operating conditions of the fuel cell, and the like.

Further, in the present embodiment, since the electrolyte membrane 2 is not affected by the equipment operation at the time of film formation and has the isotropic characteristics in the vertical and horizontal directions, the electrolyte membrane 2 is melted in the entire circumference of the power generation region. The welded portion spacing 82 was set to be equal.

Some of the electrolyte membranes 2 have anisotropy in the vertical and horizontal directions. In the electrolyte membrane 2 having anisotropy, it is advisable to adjust the intervals according to the respective characteristics in the vertical and horizontal directions. When the melt-welded portions 8 are formed at intervals, the electrolyte membrane 2 may be able to equalize the concentration of stress on the melt-welded portions 8 due to dry shrinkage or wet expansion.

Further, in the present embodiment, the seal member 7 and the electrolyte membrane end portion 21 are brought as close as possible to reduce the amount of the electrolyte membrane that does not contribute to power generation. The distance between the seal member 7 and the electrolyte membrane end portion 21 may be such that the electrolyte membrane 2 contracted by drying does not reach the inside of the seal member 7. Since the displacement of the membrane 2 becomes large, the gap between the seal member 7 and the electrolyte membrane end portion 21 may be increased. When the distance between the seal member 7 and the electrolyte membrane end portion 21 is increased, the electrolyte membrane end portion 21 is bypassed and the leak path length when one gas leaks to the other electrode can be lengthened, so that the gas leak May be reduced.

INDUSTRIAL APPLICABILITY The membrane electrode assembly of the present invention can prevent gas leaks of fuel gas and oxidant gas, and can further improve the utilization efficiency of fuel gas and oxidant gas, so that it can be used as a fuel cell for household cogeneration and vehicle installation. It can be used preferably.

1 Single Cell Module 2 Electrolyte Membrane 3 Catalyst Layer Electrode 4 Gas Diffusion Layer 6 Separator 7 Seal Member 8 Melt Welding Part 11 Membrane Electrode Assembly 12 Power Generation Area 51 First Frame Member 52 Second Frame Member 53 Third Frame Member 61 Gas Channel 21 Electrolyte Membrane Edge 81 Ultrasonic Horn 82 Melt Welding Part Interval

Claims (8)

A membrane electrode assembly for a fuel cell in which an outer peripheral portion of an electrolyte membrane is sandwiched between a resin first frame member and a resin second frame member, wherein the first frame member and the second frame member are provided. of the surface of at least either of the electrolyte membrane side, have a volume more than volume of the molten weld portion and the material of the resin material and the electrolyte membrane constituting the frame member are mixed, and bottom in a plane Equipped with a columnar recess,
The electrolyte membrane has a hole penetrating the electrolyte membrane at a position facing the recess.
Fuel cell membrane electrode assembly. The hole is formed by penetrating one of the first frame member and the second frame member that does not have the recess and the electrolyte membrane,
The recess has an inner diameter greater than the inner diameter of the hole and a volume greater than the volume of the hole ,
The membrane electrode assembly of the fuel cell according to claim 1. The first frame member and the second frame member are made of the same resin material,
The membrane electrode assembly for a fuel cell according to claim 1 or 2. A third frame member that covers a boundary surface between the first frame member and the second frame member and a processing mark of the fusion-welded portion,
The membrane electrode assembly of the fuel cell according to any one of claims 1 to 3. The third frame member is made of the same resin material as at least one of the first frame member and the second frame member that does not include the recess .
The membrane electrode assembly of the fuel cell according to claim 4. A fuel cell in which the membrane electrode assembly of the fuel cell according to any one of claims 1 to 5 is sandwiched between a pair of separators. A fuel cell in which a plurality of the fuel cells according to claim 6 are stacked. A membrane electrode assembly for a fuel cell in which an outer peripheral portion of an electrolyte membrane is sandwiched between a resin first frame member and a resin second frame member, wherein the first frame member and the second frame member are provided. Of at least one of the surface of the electrolyte membrane side, the resin material constituting the frame member and the material of the electrolyte membrane has a volume equal to or more than the volume of the melt-bonded portion mixed, and the bottom surface is flat. A certain columnar recess is provided, and the electrolyte membrane is provided with a hole penetrating the electrolyte membrane at a position facing the recess.
A method for welding a membrane electrode assembly of a fuel cell, comprising:
A method for welding a membrane electrode assembly of a fuel cell, which comprises using an ultrasonic horn to cause the melted welded portion to flow into the recessed portion for welding.

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