JP5450962B2 - Method for manufacturing membrane electrode assembly - Google Patents

Description

  The present invention relates to a method for manufacturing a membrane electrode assembly for a polymer electrolyte fuel cell.

  In recent years, fuel cells have attracted attention as highly efficient energy conversion devices. Fuel cells are roughly classified into low-temperature operating fuel cells such as alkaline, solid polymer and phosphoric acid types, and high-temperature operating fuel cells such as molten carbonate and solid oxide types, depending on the type of electrolyte used. . Among these, a polymer electrolyte fuel cell (PEFC) using a polymer electrolyte membrane having ion conductivity as an electrolyte can obtain a high output density with a compact structure, and does not use a liquid as an electrolyte. Since it can be realized with a simple system because it can be operated, it has been attracting attention as a power source for stationary use, vehicle use, portable use and the like.

  In a polymer electrolyte fuel cell, one side of a polymer electrolyte membrane is exposed to fuel gas (hydrogen, etc.) and the opposite side is exposed to an oxidant gas (air, etc.), and water is removed by a chemical reaction through the polymer electrolyte membrane. The basic principle is to synthesize and to electrically extract the reaction energy generated thereby. A porous catalyst electrode disposed on both surfaces of a polymer electrolyte membrane and integrally formed by hot pressing or the like is generally called a membrane electrode assembly (MEA). The MEA can be handled independently, and a packing is disposed between the MEA and the separator to prevent reaction gas from leaking outside. The polymer electrolyte membrane has ionic conductivity, but has a function of physically and electronically separating the fuel electrode and the oxygen electrode due to lack of air permeability and electronic conductivity. When the size of the polymer electrolyte membrane is smaller than the porous catalyst electrode, the porous catalyst electrodes are electrically short-circuited inside the MEA, and the oxidant gas and the fuel gas are mixed (cross leak). Therefore, the function as a battery is lost. Further, in the case of a fuel cell of a type that directly supplies liquid fuel such as methanol, the function as a cell is impaired by the liquid fuel leaking from the fuel electrode side to the oxygen electrode side. For this reason, the area of the polymer electrolyte membrane needs to be equal to or larger than the area of the porous catalyst electrode. Therefore, the gas seal and the support structure are usually configured by extending the polymer electrolyte membrane beyond the peripheral edge of the porous catalyst electrode and sandwiching it between the packing and the separator.

  By the way, the polymer electrolyte membrane is an extremely thin film material, so it is difficult to handle it, and it is difficult to handle the reaction gas when joining with electrodes or when assembling a plurality of single cells in a stack. Frequently, wrinkles occur at the peripheral edge, which is important to the user. In a unit cell or stack assembled using such a polymer electrolyte membrane in which wrinkles are generated, there is a high possibility that the reaction gas leaks from the site where the wrinkles are generated. Even in the absence of wrinkles or the like, the polymer electrolyte membrane is a member having the lowest mechanical strength among all the constituent members constituting the stack, and thus is easily damaged. Therefore, in order to improve the reliability and maintainability of the solid polymer fuel cell, it is desired to reinforce the polymer electrolyte membrane part. Further, as described above, in order to prevent an electrical short circuit at the periphery of the polymer electrolyte membrane, conventionally, the area of the polymer electrolyte membrane is larger than that of the electrode layer so that the polymer electrolyte membrane extends laterally beyond the end of the electrode layer. MEAs incorporating large electrolyte membranes are being manufactured. However, when manufacturing MEAs having different sizes of the electrolyte membrane and the electrode layer, it is necessary to cut them out and align them separately, resulting in a decrease in productivity due to an increase in the number of steps.

  By applying a thermoplastic polymer to the peripheral portion of the MEA having the same size as the gas diffusion electrode or larger than the gas diffusion electrode and having a polymer electrolyte membrane by means of injection molding or compression molding, the thermoplastic polymer becomes Integrated into the interior of the sealing end of the gas diffusion support and encapsulating both surrounding regions of the gas diffusion support and the polymer electrolyte membrane, thus having a fluid impermeable seal of thermoplastic polymer A method of forming a membrane electrode assembly is known (Patent Document 1).

  In order to effectively reinforce the polymer electrolyte membrane and greatly improve the handling workability of the fuel cell structure, a frame member is press-fitted into the outer peripheral edge of the porous body fixed on both sides of the polymer electrolyte membrane. A method for firmly and reliably integrating a porous body and a frame member is known (Patent Document 2).

JP 2005-516350 A JP 10-199551 A

  In the method described in Patent Document 1, when a thermoplastic polymer is applied by injection molding to the peripheral portion of an MEA having a polymer electrolyte membrane larger than the gas diffusion electrode, an electrolyte membrane extending beyond the peripheral portion of the gas diffusion electrode is obtained. The gas may leak due to movement due to the resin flow at the time of injection molding and exposure to the surface, or due to a load applied to the electrolyte membrane portion at the edge portion of the gas diffusion electrode to cause damage. Further, depending on the molding pressure and osmotic pressure of the molding resin, the resin excessively enters the gas diffusion electrode. The resin that has excessively penetrated into the gas diffusion electrode may damage the MEA as a result of compressing the electrolyte membrane of MEA or dispersing the fastening pressure of the cell when the MEA is incorporated into a fuel cell. May be reduced. On the other hand, since the space in the mold is very narrow in the peripheral portion of the gas diffusion electrode, the molding resin does not reach a part of the gas diffusion electrode, and the shape of the seal portion may not be precisely molded.

  Further, in the method described in Patent Document 1, when a thermoplastic polymer is applied by injection molding to the peripheral portion of the MEA having a polymer electrolyte membrane of the same size as the gas diffusion electrode, the anode side and the cathode side When the sizes of the gas diffusion electrodes are different, the polymer electrolyte membrane bonded to the large-side gas diffusion electrode may be peeled off from the gas diffusion electrode by the flow of the molding resin. Furthermore, since the mold space above the polymer electrolyte membrane joined to the large gas diffusion electrode is narrow, defective filling of the resin is likely to occur.

  In the method described in Patent Document 2, it is difficult to sufficiently press-fit the frame member into the outer peripheral edge of the porous body and firmly integrate it, and it is extremely difficult to reliably seal the boundary surface between the frame member and the MEA. Since it is difficult, problems such as gas leakage from the joint and cell destruction may occur.

  Therefore, the first object of the present invention is to control the penetration of the molding resin into the gas diffusion layer and / or the electrode layer when the reinforcing resin frame is provided on the MEA. The second object of the present invention is to provide a gas diffusion layer and / or an electrode of a polymer electrolyte membrane by a resin flow when a reinforcing resin frame is provided on an MEA having different gas diffusion layer sizes on the anode side and the cathode side. It is to prevent peeling from the layer and to improve resin filling properties. Overall, an object of the present invention is to improve the reliability, mechanical strength, and handleability of a seal in a polymer electrolyte fuel cell.

According to the present invention,
(1) A polymer electrolyte membrane, a first electrode layer provided on one side of the electrolyte membrane, and a first porous layer provided on the opposite side of the first electrode layer from the electrolyte membrane A gas diffusion layer, a second electrode layer provided on the other side of the electrolyte membrane, and a second porous gas diffusion provided on the opposite side of the second electrode layer from the electrolyte membrane A membrane electrode assembly including a layer, and by molding the membrane electrode assembly, the entire outer peripheral edge of the electrolyte membrane and the outer peripheral edges of the first and second gas diffusion layers are molded. When providing a resin frame so as to surround at least the vicinity of the first and second electrode layers, the resin frame material is suppressed or prevented from entering the gas diffusion layer and / or the electrode layer. A method of manufacturing a reinforced membrane electrode assembly for a polymer electrolyte fuel cell is provided.

Also according to the present invention,
(2) The method according to (1) is provided, wherein a protrusion is provided on a mold used for molding, thereby suppressing or preventing intrusion of the resin frame material into the gas diffusion layer and / or the electrode layer. Is done.

Also according to the present invention,
(3) The method according to (2), wherein the protrusion acts as a baffle against the flow of the resin frame material.

Also according to the present invention,
(4) The method according to (2) or (3), wherein the protrusions at least partially compress the gas diffusion layer.

Also according to the present invention,
(5) A gas introduction part is provided in the mold used for the mold forming, and the gas diffusion layer of the resin frame material and / or the gas frame is blown or pressurized with a gas so as to resist the flow of the resin frame material. Or the method as described in (1) which suppresses or prevents the penetration | invasion to this electrode layer is provided.

Also according to the present invention,
(6) The shielding material is disposed between the gas diffusion layer and / or the electrode layer and the resin frame, thereby suppressing or preventing the resin frame material from entering the gas diffusion layer and / or the electrode layer. The method according to (1) is provided.

Also according to the present invention,
(7) The method according to (6), wherein the shield is configured by bending a peripheral edge of the polymer electrolyte membrane.

Also according to the present invention,
(8) Suppressing or preventing the resin frame material from entering the gas diffusion layer and / or the electrode layer by partially closing at least a part of the porous portion of the gas diffusion layer and / or the electrode layer. The method according to (1) is provided.

Also according to the present invention,
(9) Inhibiting or preventing the resin frame material from entering the gas diffusion layer and / or the electrode layer by tapering the peripheral edge of the gas diffusion layer and / or the electrode layer. Is provided.

Also according to the present invention,
(10) Inhibiting or preventing the resin frame material from entering the gas diffusion layer and / or the electrode layer by making the peripheral portion of the gas diffusion layer and / or the electrode layer have a reverse taper shape. ) Is provided.

Also according to the present invention,
(11) A polymer electrolyte membrane, a first electrode layer provided on one surface side of the electrolyte membrane, and a first gas provided on the opposite side of the first electrode layer from the electrolyte membrane A diffusion layer; a second electrode layer provided on the other surface side of the electrolyte membrane; and a second gas diffusion layer provided on the opposite side of the second electrode layer from the electrolyte membrane. A membrane electrode assembly, wherein the first gas diffusion layer and the first electrode layer are configured such that the entire outer peripheral edge of the first gas diffusion layer is within the range of the outer peripheral edge of the electrolyte membrane. Arranged on the surface of the electrolyte membrane such that the surface region of the electrolyte membrane remains between the outer periphery of the first electrode layer and the outer periphery of the electrolyte membrane over the entire outer periphery of the electrode layer. And the second gas diffusion layer extends to at least a part on the opposite side of the surface region over the entire outer peripheral edge of the electrolyte membrane. An electrode assembly is prepared, and at least the first and second outer peripheries of the electrolyte membrane and the first and second gas diffusion layers are formed on the membrane electrode assembly by molding. When a resin frame is provided so as to surround the vicinity of the second electrode layer and to be fixed to at least a part of the surface region, the flow front portion of the resin frame material has the electrolyte membrane and the second electrode layer. A method of manufacturing a membrane electrode assembly for a polymer electrolyte fuel cell is provided, which is characterized in that it does not hit the interface with the fuel cell.

Also according to the present invention,
(12) By providing a recess in the mold used for molding, the flow tip of the resin frame material is prevented from hitting the interface between the electrolyte membrane and the second electrode layer. A described method is provided.

Also according to the present invention,
(13) The method according to (12), wherein after the filling of the resin frame material, the resin frame is flattened by further compressing the concave portion.

Also according to the present invention,
(14) By configuring the mold so that the resin frame is offset toward the first gas diffusion layer, the flow front end of the resin frame material is an interface between the electrolyte membrane and the second electrode layer. The method according to (11) is provided so as not to hit.

Also according to the present invention,
(15) The molding is performed in two steps, and at least the vicinity of the second electrode layer on the outer periphery of the second gas diffusion layer is surrounded by the first molding, and the second molding is performed. The resin frame is provided so as to surround at least the vicinity of the first electrode layer on the outer peripheral edge of the first gas diffusion layer and to be fixed to at least a part of the surface region. A method is provided.

Also according to the present invention,
(16) The resin frame is provided so as to surround at least the vicinity of the first electrode layer on the outer peripheral edge of the first gas diffusion layer by the molding and to be fixed to at least a part of the surface region. , (11) is provided.

Also according to the present invention,
(17) The method according to (11), wherein a discharge port is provided in the vicinity of a portion in contact with the first gas diffusion layer of a mold used for the mold forming.

Also according to the present invention,
(18) The method according to (17), wherein the discharge port is made of a porous material.

Also according to the present invention,
(19) The method according to (11), wherein the thickness of the second gas diffusion layer is made thinner than that of the first gas diffusion layer.

Also according to the present invention,
(20) The method according to (11), wherein the second gas diffusion layer is made thinner at the periphery.

Also according to the present invention,
(21) The method according to (11), wherein an outsert is installed in the mold and the resin frame material is injected toward the surface region.

Also according to the present invention,
(22) The method according to (11), wherein an outsert with a step is installed in the mold and the resin frame material is injected toward the step part of the outsert.

Also according to the present invention,
(23) A reinforced membrane electrode assembly for a polymer electrolyte fuel cell manufactured by the method according to any one of (1) to (22) is provided.

  According to the present invention, when the reinforcing resin frame is provided on the MEA, excessive penetration of the molding resin into the gas diffusion layer and / or the electrode layer is prevented. Further, according to the present invention, when the reinforcing resin frame is provided on the MEA in which the size of the gas diffusion layer is different between the anode side and the cathode side, the polymer electrolyte membrane by the resin flow is removed from the gas diffusion layer and / or the electrode layer. Peeling is prevented and the resin filling property is improved. Therefore, according to the present invention, the reliability, mechanical strength and handleability of the seal in the polymer electrolyte fuel cell are improved.

  Hereinafter, the present invention will be described in detail with reference to the drawings. Each drawing is schematically drawn so that the invention can be easily understood, and the relative relationship between the sizes of the illustrated members accurately represents the actual size relationship in the embodiment. Please note that it was not done.

  A manufacturing method of a membrane electrode assembly that achieves the first object of the present invention includes a polymer electrolyte membrane, a first electrode layer provided on one surface side of the electrolyte membrane, and the first electrode layer A first porous gas diffusion layer provided on the opposite side of the electrolyte membrane, a second electrode layer provided on the other surface side of the electrolyte membrane, and the electrolyte of the second electrode layer A membrane electrode assembly including a second porous gas diffusion layer provided on the opposite side of the membrane is prepared, and the outer peripheral edge of the electrolyte membrane is formed by molding the membrane electrode assembly. When the resin frame is provided so as to surround all and at least the vicinity of the first and second electrode layers on the outer periphery of the first and second gas diffusion layers, the gas diffusion layer of the resin frame material and / or Alternatively, intrusion into the electrode layer is suppressed or prevented.

  One means for suppressing or preventing the penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention is shown in FIG. FIG. 1 is a partial cross-sectional view showing a state in which a membrane electrode assembly is set in a mold. FIG. 1A shows a polymer electrolyte membrane 13, which is a part of a membrane electrode assembly, a first electrode layer 12, and a first gas diffusion layer 11, and further for molding. An upper mold 10 is shown. The upper mold 10 is provided with a protrusion 20, and this protrusion 20 acts as a baffle and inhibits the flow of the resin frame material indicated by the dashed arrow, so that the gas diffusion layer 11 and / or the electrode layer 12 is formed. Intrusion of the resin frame material can be suppressed or prevented. FIG. 1B is a partial cross-sectional view similar to FIG. 1A except that the shape of the protrusion provided on the mold is different. The protrusion 21 shown in FIG. 1B has a tapered shape. For this reason, the flow of the resin frame material indicated by the broken line arrow is braked, and the penetration of the resin frame material into the gas diffusion layer 11 and / or the electrode layer 12 can be suppressed or prevented. FIG. 1C is a partial cross-sectional view similar to FIG. 1A except that the shape of the protrusion provided on the mold is different. The protrusion 22 shown in FIG. 1C has a semicircular shape. For this reason, the flow of the resin frame material indicated by the broken line arrow is braked, and the penetration of the resin frame material into the gas diffusion layer 11 and / or the electrode layer 12 can be suppressed or prevented.

  Another means for suppressing or preventing the penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention is shown in FIG. FIG. 2 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 2A shows a polymer electrolyte membrane 13, which is a part of a membrane electrode assembly, a first electrode layer 12, and a first gas diffusion layer 11, and further for molding. An upper mold 10 is shown. The upper mold 10 is provided with a protrusion 30. The protrusion 30 inhibits the flow of the resin frame material indicated by the dashed arrow, and at the same time, the gas diffusion layer 11 is at least partially compressed, so that the gas Intrusion of the resin frame material into the diffusion layer 11 and / or the electrode layer 12 can be suppressed or prevented. FIG. 2B is a partial cross-sectional view similar to FIG. 2A except that the positions of the protrusions provided on the mold are different. The protrusion 31 shown in FIG. 2 (B) is not at a position that hinders the flow of the resin frame material indicated by the dashed arrow. However, the protrusion 31 can at least partially compress the gas diffusion layer 11 to suppress or prevent the resin frame material from entering the gas diffusion layer 11 and / or the electrode layer 12.

  FIG. 3 shows still another means for suppressing or preventing the resin frame material from entering the gas diffusion layer and / or the electrode layer according to the present invention. FIG. 3 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 3 shows a polymer electrolyte membrane 13, a first electrode layer 12, and a first gas diffusion layer 11 that are a part of the membrane electrode assembly, and an upper die 10 for molding. It is shown. The upper mold 10 is provided with a gas introduction part 40. Gas is diffused from the gas introduction part 40 by blowing or pressurizing the gas against the flow of the resin frame material indicated by the broken arrow. Intrusion of the resin frame material into the layer 11 and / or the electrode layer 12 can be suppressed or prevented.

  FIG. 4 shows still another means for suppressing or preventing penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention. FIG. 4 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. 4 shows a polymer electrolyte membrane 13, which is a part of a membrane electrode assembly, a first electrode layer 12, and a first gas diffusion layer 11, and an upper die 10 for molding. It is shown. In this embodiment, the shielding object 50 is disposed between the gas diffusion layer 11 and / or the electrode layer 12 and the resin frame to be formed. The shield 50 may be an object arranged so as to be close to the gas diffusion layer 11 and / or the electrode layer 12 when the membrane electrode assembly is set in a mold. Further, as shown in FIG. 4, prior to resin frame molding, the shielding object 50 is arranged by molding a high viscosity resin or the like in the vicinity of the gas diffusion layer 11 and / or the electrode layer 12 from the direction indicated by the solid line arrow. May be. Such a shield 50 can suppress or prevent the resin frame material from entering the gas diffusion layer 11 and / or the electrode layer 12.

  FIG. 5 shows still another means for suppressing or preventing penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention. FIG. 5 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 5 shows a polymer electrolyte membrane 13, a first electrode layer 12, and a first gas diffusion layer 11 that are a part of the membrane electrode assembly, and an upper die 10 for molding. It is shown. In this embodiment, the peripheral part of the polymer electrolyte membrane 13 is bent to form a shielding object between the gas diffusion layer 11 and / or the electrode layer 12 and the resin frame to be formed. The polymer electrolyte membrane 13 bent in this way serves as a shield, and the penetration of the resin frame material into the gas diffusion layer 11 and / or the electrode layer 12 can be suppressed or prevented.

  FIG. 6 shows still another means for suppressing or preventing penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention. FIG. 6 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 6 shows a polymer electrolyte membrane 13, a first electrode layer 12, and a first gas diffusion layer 11, which are part of a membrane electrode assembly, and an upper die 10 for molding. It is shown. In this embodiment, at least a portion 60 of the porous portion of the portion in contact with the resin frame of the gas diffusion layer 11 and / or the electrode layer 12 is partially blocked in advance. Rubber, resin, or the like can be used to close the porous portion. Thus, by previously closing the gas diffusion layer 11 and / or the electrode layer 12, it is possible to suppress or prevent the resin frame material from entering the gas diffusion layer 11 and / or the electrode layer 12.

  FIG. 7 shows still another means for suppressing or preventing penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention. FIG. 7 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 7 shows a polymer electrolyte membrane 13, a first electrode layer 12, and a first gas diffusion layer 11 that are a part of the membrane electrode assembly, and an upper die 10 for molding. It is shown. In this embodiment, the portion of the gas diffusion layer 11 and / or electrode layer 12 that contacts the resin frame is tapered. By forming the gas diffusion layer 11 and / or the electrode layer 12 in this manner, the molding pressure of the resin frame material on the gas diffusion layer 11 and / or the electrode layer 12 is relieved, and the gas diffusion layer 11 and / or the electrode are reduced. Intrusion of the resin frame material into the layer 12 can be suppressed or prevented.

  FIG. 8 shows still another means for suppressing or preventing penetration of the resin frame material into the gas diffusion layer and / or electrode layer according to the present invention. FIG. 8 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 8 shows a polymer electrolyte membrane 13, a first electrode layer 12, and a first gas diffusion layer 11 that are a part of a membrane electrode assembly, and an upper die 10 for molding. It is shown. In this embodiment, the portion of the gas diffusion layer 11 and / or the electrode layer 12 that is in contact with the resin frame is formed in a reverse taper shape. Thus, by making the gas diffusion layer 11 and / or the electrode layer 12 have a reverse taper shape, the air 70 pushed by the resin frame material during molding is accumulated in the taper. The air 70 accumulated in the back of the taper resists the flow of the resin frame material, thereby suppressing or preventing the resin frame material from entering the gas diffusion layer 11 and / or the electrode layer 12.

  A method of manufacturing a membrane electrode assembly that achieves the second object of the present invention includes a polymer electrolyte membrane, a first electrode layer provided on one surface side of the electrolyte membrane, and the first electrode layer. A first gas diffusion layer provided on the opposite side of the electrolyte membrane, a second electrode layer provided on the other surface side of the electrolyte membrane, and the electrolyte membrane of the second electrode layer Is a membrane electrode assembly including a second gas diffusion layer provided on the opposite side, wherein the first gas diffusion layer and the first electrode layer are outer peripheral edges of the first gas diffusion layer The electrolyte is entirely within the range of the outer peripheral edge of the electrolyte membrane, and the electrolyte is disposed between the outer peripheral edge of the first electrode layer and the outer peripheral edge of the electrolyte membrane over the entire outer peripheral edge of the first electrode layer. The second gas diffusion layer is disposed on the surface of the electrolyte membrane so as to leave a surface region of the membrane, and the second gas diffusion layer extends over the entire outer periphery of the electrolyte membrane. A membrane electrode assembly extending to at least a part on the opposite side of the membrane electrode assembly, and forming all of the outer peripheral edge of the electrolyte membrane as well as the first by molding the membrane electrode assembly. When the resin frame is provided so as to surround at least the vicinity of the first and second electrode layers on the outer peripheral edge of the second gas diffusion layer and to be fixed to at least a part of the surface region. It is characterized in that the flow front portion of the material does not hit the interface between the electrolyte membrane and the second electrode layer.

  FIG. 9 shows one means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 9 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 9, the polymer electrolyte membrane 130, which is a part of the membrane electrode assembly, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In the embodiment shown in FIG. 9, the lower mold 160 in which a portion corresponding to the second gas diffusion layer 150 is dug is used. By digging the lower mold 160 in this way, it is possible to prevent the flow front end portion (broken arrow) of the resin frame material from hitting the interface between the polymer electrolyte membrane 130 and the second electrode layer 140. This prevents the polymer electrolyte membrane 130 from being peeled off from the gas diffusion layer 150 and / or the electrode layer 140 due to the resin flow during mold forming.

  FIG. 10 shows another means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 10 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 10 shows a polymer electrolyte membrane 130, a first electrode layer 120, and a first gas diffusion layer 110, which are part of a membrane electrode assembly, and an upper mold 100 for molding. It is shown. The upper mold 100 is provided with a recess 200. As a result of the flow of the flow front portion (broken arrow) of the resin frame material toward the concave portion 200 due to the recess 200, the flow front portion (broken arrow) of the resin frame material becomes the polymer electrolyte membrane 130 and the second electrode layer 140. It can be made not to hit the interface.

  FIG. 11 shows still another means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 11 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 11 shows a polymer electrolyte membrane 130, a first electrode layer 120, and a first gas diffusion layer 110, which are part of a membrane electrode assembly, and further an upper mold 100 for molding. It is shown. The upper mold 100 is provided with a compression means 300 that forms a recess during resin filling and that can flatten the resin frame after resin filling. The compression means 300 causes the flow of the flow front portion (dashed arrow) of the resin frame material to approach the compression means 300 during resin filling, so that the flow front portion (dashed arrow) of the resin frame material and the polymer electrolyte membrane 130 The contact with the second electrode layer 140 can be prevented. After the resin filling, the convex part of the resin frame formed corresponding to the concave part can be flattened by compressing the compressing means 300.

  FIG. 12 shows still another means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 12 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 12, the polymer electrolyte membrane 130, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane, which are part of the membrane electrode assembly, are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In the embodiment shown in FIG. 12, a mold configured so that the formed resin frame is offset toward the first gas diffusion layer 110 is used. In the embodiment shown in FIG. 12, the lower mold 160 is dug as shown in FIG. 9, and the upper mold 100 dug so that the resin frame portion corresponding to the first gas diffusion layer 110 is relatively thick. use. By using the mold configured such that the resin frame is offset toward the first gas diffusion layer 110 in this way, the flow front end (broken arrow) of the resin frame material is formed between the polymer electrolyte membrane 130 and the second. It is possible not to hit the interface with the electrode layer 140.

  In order to prevent the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer, the molding is performed in two steps, and the second gas is formed by the first molding. Surrounding at least the vicinity of the second electrode layer on the outer peripheral edge of the diffusion layer, surrounding at least the vicinity of the first electrode layer on the outer peripheral edge of the first gas diffusion layer by the second molding, and surface area A resin frame may be provided so as to be fixed to at least a part of the resin frame. This embodiment is shown in FIG. FIG. 13 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 13, the polymer electrolyte membrane 130 which is a part of the membrane electrode assembly, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In the embodiment shown in FIG. 13, as shown in FIG. 13A, at least the vicinity of the second electrode layer on the outer peripheral edge of the second gas diffusion layer is surrounded by the first molding. In the first molding, since there is no mold space on the first gas diffusion layer side, the flow front portion (broken arrow) of the resin frame material is at the interface between the polymer electrolyte membrane 130 and the second electrode layer 140. Don't hit. Next, as shown in FIG. 13B, at least the vicinity of the first electrode layer on the outer peripheral edge of the first gas diffusion layer is surrounded by the second molding. Also in the second molding, since the second gas diffusion layer side is already surrounded by the resin frame 400, the flow front portion (broken arrow) of the resin frame material is the polymer electrolyte membrane 130 and the second electrode layer 140. Does not hit the interface.

  FIG. 14 shows still another means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 14 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. FIG. 14A shows a polymer electrolyte membrane 130, a first electrode layer 120, and a first gas diffusion layer 110, which are part of a membrane electrode assembly, and further for molding. An upper mold 100 is shown. The upper mold 100 is provided with a discharge port 500 in the vicinity of a portion in contact with the first gas diffusion layer. By extracting the resin frame material and the gas in the mold space in the direction of the solid line arrow from the discharge port 500, the flow of the flow front portion (broken line arrow) of the resin frame material approaches the discharge port 500 side. As a result, the flow of the resin frame material It is possible to prevent the tip portion (broken arrow) from hitting the interface between the polymer electrolyte membrane 130 and the second electrode layer 140. Alternatively, instead of the discharge port 500, a discharge port 510 made of a porous material may be provided as shown in FIG.

  In order to prevent the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer, the thickness of the second gas diffusion layer is set to the first thickness as shown in FIG. It can be made thinner than the gas diffusion layer. FIG. 15 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 15, the polymer electrolyte membrane 130, which is a part of the membrane electrode assembly, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In this embodiment, the thickness of the second gas diffusion layer 150 is made thinner than that of the first gas diffusion layer 110. By doing so, the space on the first gas diffusion layer side of the membrane electrode assembly is widened, and the flow front portion (broken arrow) of the resin frame material is the interface between the polymer electrolyte membrane 130 and the second electrode layer 140. Can be avoided. Moreover, as a result of the space on the first gas diffusion layer side of the membrane electrode assembly being widened, the filling property of the resin frame material on the first gas diffusion layer side, which is a relatively narrow portion, is improved.

  In order to prevent the flow front end portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer, the second gas diffusion layer is made thinner at the periphery as shown in FIG. May be. FIG. 16 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 16, the polymer electrolyte membrane 130 which is a part of the membrane electrode assembly, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In this aspect, the second gas diffusion layer 150 is made thinner at the periphery. FIG. 16 shows the peripheral portion of the second gas diffusion layer 150 having a C-plane shape. The second gas diffusion layer 150 may have the peripheral edge thereof together with the second electrode layer 140 in some cases. An R shape, a staircase shape, or other shapes may be adopted as long as the thickness is thinner at the portion. By making the second gas diffusion layer thinner at the periphery thereof, the space on the first gas diffusion layer side of the membrane electrode assembly is expanded, and the flow front portion (broken arrow) of the resin frame material is a polymer electrolyte. It is possible not to hit the interface between the film 130 and the second electrode layer 140. Moreover, as a result of the space on the first gas diffusion layer side of the membrane electrode assembly being widened, the filling property of the resin frame material on the first gas diffusion layer side, which is a relatively narrow portion, is improved.

  FIG. 17 shows still another means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 17 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 17, the polymer electrolyte membrane 130 which is a part of the membrane electrode assembly, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In this embodiment, the outsert 700 is installed outside the membrane electrode assembly, and the resin frame material is injected from the injection port 600 provided in the upper mold 100 toward the surface region of the polymer electrolyte membrane 130. The flow front portion (broken arrow) of the injected resin frame material does not hit the interface between the polymer electrolyte membrane 130 and the second electrode layer 140. In addition, since the resin is directly injected to the first gas diffusion layer, which is a relatively narrow portion, the filling property of the resin frame material is improved.

  FIG. 18 shows still another means for preventing the flow front portion of the resin frame material from hitting the interface between the polymer electrolyte membrane and the second electrode layer according to the present invention. FIG. 18 is a partial cross-sectional view showing a state in which the membrane electrode assembly is set in a mold. In FIG. 18, the polymer electrolyte membrane 130 which is a part of the membrane electrode assembly, the first electrode layer 120, the first gas diffusion layer 110, and the other surface side of the electrolyte membrane are provided. A second electrode layer 140 and a second gas diffusion layer 150 are shown, and an upper die 100 and a lower die 160 for molding are shown. In this embodiment, a stepped outsert 700 is installed outside the membrane electrode assembly, and a resin frame material is injected from the injection port 600 provided in the upper mold 100 toward the stepped portion of the outsert 700. The flow front portion (broken arrow) of the injected resin frame material does not hit the interface between the polymer electrolyte membrane 130 and the second electrode layer 140.

The polymer electrolyte membrane used in the membrane electrode assembly according to the present invention is not particularly limited as long as it has high ion conductivity, electronic insulation, and gas impermeability. Any molecular electrolyte membrane may be used. As a typical example, a proton (H ⁺ ) conductive resin having a fluorinated polymer as a skeleton and a group such as a sulfonic acid group, a carboxyl group, a phosphoric acid group, or a phosphonic group can be given. Since the thickness of the polymer electrolyte membrane has a great influence on the resistance, a thinner one is required as long as the electronic insulation and gas impermeability are not impaired. Specifically, the thickness is 5 to 50 μm, preferably 10 to 10 μm. It is set within the range of 30 μm. Representative examples of the polymer electrolyte membrane include Nafion (registered trademark) membrane (manufactured by DuPont) and Flemion (registered trademark) membrane (manufactured by Asahi Glass Co., Ltd.), which are perfluoropolymers having a sulfonic acid group in the side chain. Also, GORE-SELECT (registered trademark) (manufactured by Japan Gore-Tex), which is a reinforced polymer electrolyte membrane in which an expanded porous polytetrafluoroethylene membrane is impregnated with an ion exchange resin, can be suitably used.

The electrode layer used in the membrane electrode assembly according to the present invention is not particularly limited as long as it contains catalyst particles and an ion exchange resin, and conventionally known ones can be used. The catalyst is usually made of a conductive material carrying catalyst particles. The catalyst particles may be any catalyst particles that have a catalytic action in the oxidation reaction of hydrogen or the reduction reaction of oxygen. In addition to platinum (Pt) and other noble metals, iron, chromium, nickel, and alloys thereof may be used. it can. As the conductive material, carbon-based particles such as carbon black, activated carbon, graphite and the like are suitable, and fine powder particles are particularly preferably used. Typically, carbon black particles having a surface area of 20 m ² / g or more carry noble metal particles such as Pt particles or alloy particles of Pt and other metals. In particular, for anode catalysts, Pt is vulnerable to carbon monoxide (CO) poisoning. Therefore, when a fuel containing CO such as methanol is used, alloy particles of Pt and ruthenium (Ru) are used. It is preferable. The ion exchange resin in the electrode layer is a material that supports the catalyst and serves as a binder for forming the electrode layer, and has a role of forming a passage for ions and the like generated by the catalyst to move. As such an ion exchange resin, the thing similar to what was previously demonstrated in relation to the polymer electrolyte membrane can be used. The electrode layer is preferably porous so that a fuel gas such as hydrogen or methanol can be in contact with the catalyst as much as possible on the anode side and an oxidant gas such as oxygen or air on the cathode side. Further, the amount of catalyst contained in the electrode layer is, 0.01 to 1 mg / cm ^2, preferably suitably be in the range of 0.1-0.5 mg / cm ^2. The thickness of the electrode layer is generally in the range of 1 to 20 μm, preferably 5 to 15 μm.

  The gas diffusion layer used in the membrane electrode assembly according to the present invention is a sheet material having conductivity and air permeability. Representative examples include those obtained by subjecting a breathable conductive base material such as carbon paper, carbon woven fabric, carbon nonwoven fabric, carbon felt or the like to a water repellent treatment. A porous sheet obtained from carbon-based particles and fluorine-based resin can also be used. For example, a porous sheet obtained by forming carbon black into a sheet using polytetrafluoroethylene as a binder can be used. The thickness of the gas diffusion layer is generally 50 to 500 μm, preferably 100 to 200 μm.

  A membrane electrode assembly or a membrane electrode junction precursor sheet is produced by joining the electrode layer, the gas diffusion layer, and the polymer electrolyte membrane. As a joining method, any conventionally known method can be adopted as long as a precise joining with a low contact resistance can be achieved without damaging the polymer electrolyte membrane. In joining, first, an electrode layer and a gas diffusion layer are combined to form an anode electrode or a cathode electrode, and then these can be joined to the polymer electrolyte membrane. For example, an anode layer or a cathode electrode is formed by preparing an electrode layer forming coating solution containing catalyst particles and an ion exchange resin using an appropriate solvent and applying the coating solution to a gas diffusion layer sheet material. It can be joined to the molecular electrolyte membrane by hot pressing. Further, after the electrode layer is combined with the polymer electrolyte membrane, a gas diffusion layer may be combined on the electrode layer side. When combining the electrode layer and the polymer electrolyte membrane, a conventionally known method such as a screen printing method, a spray coating method, or a decal method may be employed.

  The resin material for the resin frame used in the membrane electrode assembly according to the present invention has sufficient stability in the use environment of the fuel cell, specifically heat resistance, acid resistance, hydrolysis resistance, creep resistance, etc. Is a prerequisite. Further, it is preferable that the resin material has characteristics suitable for molding, and particularly has high fluidity during molding. Further, when the resin material is a thermoplastic resin, its molding shrinkage is preferably small, and when it is a thermosetting resin, its curing shrinkage is preferably small. Specific examples of the thermoplastic resin include liquid crystal polymer (LCP), polyphenylene sulfide (PPS), polyethersulfone (PES), polysulfone (PSF), polyetheretherketone (PEEK), polyimide (PI), polybutylene terephthalate ( Examples thereof include plastics or elastomers such as PBT), polyamide (PA), polypropylene (PP), polyurethane, and polyolefin. Specific examples of the thermosetting resin include plastics or elastomers such as epoxy resin, phenol resin, dicyclopentadiene resin, silicon rubber, fluorine rubber, and ethylene propylene diene rubber (EPDM).

  The resin frame used in the membrane electrode assembly according to the present invention is provided by molding. Molding includes injection molding, reaction injection molding, transfer molding, direct pressure molding, cast molding, and the like, and those skilled in the art can appropriately select a molding method according to the properties of the resin used. Since the MEA on which the resin frame is provided has a thickness of several hundreds of μm, it is necessary to manufacture a mold for defining the resin frame so as to be adapted thereto. Further, in order to prevent the MEA having a low strength from being crushed when the mold is clamped, it is preferable to provide a nested structure in the mold to adjust the thickness of the MEA portion. Furthermore, it is preferable to provide a suction mechanism for fixing the MEA to the mold so that the MEA does not shift during mold clamping. In particular, injection molding, reaction injection molding, and transfer molding are useful in that a series of operations such as insert placement, molding, and removal of a molded product can be performed fully automatically.

  A membrane electrode assembly obtained as described above is fueled by laminating 10 to 100 cells alternately with a separator plate and a cooling unit according to a conventionally known method so that the anode side and the cathode side are on a predetermined side. Battery stack can be assembled.

It is a partial cross section figure which shows the state which set the membrane electrode assembly to the type | mold in the method by this invention which achieves the 1st objective. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a partial cross section figure which shows the state which set the membrane electrode assembly to the type | mold in the method by this invention which achieves a 2nd objective. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention. It is a fragmentary cross-sectional view which shows the state which set the membrane electrode assembly to the type | mold in the method by another aspect of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Upper mold | type 11 1st gas diffusion layer 12 1st electrode layer 13 Polymer electrolyte membrane 20 Projection part 21 Projection part 22 Projection part 30 Projection part 31 Projection part 40 Gas introduction part 50 Shielding object 60 Occlusion part 70 Air 100 Upper part Mold 110 First gas diffusion layer 120 First electrode layer 130 Polymer electrolyte membrane 140 Second electrode layer 150 Second gas diffusion layer 160 Lower mold 200 Recess 300 Compression means 400 Resin frame 410 Seal member 500 Discharge port 510 Porous outlet 600 Outlet

Claims (6)

A polymer electrolyte membrane; a first electrode layer provided on one side of the electrolyte membrane; and a first porous gas diffusion provided on the opposite side of the first electrode layer from the electrolyte membrane A second electrode layer provided on the other surface side of the electrolyte membrane, and a second porous gas diffusion layer provided on the opposite side of the second electrode layer from the electrolyte membrane. And a membrane electrode assembly including the entire outer peripheral edge of the electrolyte membrane and at least the outer peripheral edges of the first and second gas diffusion layers by molding the membrane electrode assembly. When the resin frame is provided so as to surround the vicinity of the first and second electrode layers, the resin frame material of the resin frame material can be formed without providing a protrusion that compresses the gas diffusion layer in the mold used for the mold forming. wherein the suppression Wins Rukoto entry into the gas diffusion layer and the electrode layer, complement for a polymer electrolyte fuel cell Membrane electrode assembly manufacturing method. Projections on the mold used to mold the molding (the gas diffusion layer is not intended to compress) that suppress Wins entry into the gas diffusion layer and the electrode layer of the resin frame material by providing the claim The method according to 1.   The method according to claim 2, wherein the protrusion acts as a baffle against the flow of the resin frame material. The gas inlet portion provided in the mold used for mold shaping, the gas diffusion layer and the electrode of said resin frame material by pressure blowing gas, or a gas pressurized to resist the flow of the resin frame material that suppress Wins penetration into the layer, the method of claim 1. That suppress Wins entry into the gas diffusion layer and the electrode layer of the resin frame material by a peripheral edge of the gas diffusion layer and the electrode layer in a tapered shape, the method according to claim 1 . That suppress Wins entry into the gas diffusion layer and the electrode layer of the resin frame material by a peripheral edge of the gas diffusion layer and the electrode layer in opposite tapered according to claim 1 Method.

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