JP2013062049A - Manufacturing method of electrode-membrane-frame assembly and manufacturing method of fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of an electrode-membrane-frame assembly which allows further enhancement of power generation performance and durability of a fuel cell.SOLUTION: In the manufacturing method of an electrode-membrane-frame assembly for injection molding a frame by pouring a molten resin material into a die in a state where protrusions, provided on an inner surface of the die, are pierced into the peripheral edge of a gas diffusion layer and movement of which in the plane direction is regulated, the protrusions are formed to have non-uniform heights from the inner surface of the die, or a plurality of protrusions are provided intermittently when viewed from the thickness direction of the die. The membrane-electrode assembly has a movement regulation region overlapping the protrusions when it is viewed from the thickness direction of the die in a state where the movement is regulated. The movement regulation region is located in the vicinity of a gate for pouring the resin material provided in the die.

Description

  The present invention relates to a fuel cell used as a driving source for a mobile body such as an automobile, a distributed power generation system, a household cogeneration system, and the like, and in particular, a method for manufacturing an electrode-membrane-frame assembly provided in the fuel cell. About.

  BACKGROUND ART A fuel cell (for example, a polymer electrolyte fuel cell) is an apparatus that generates electric power and heat simultaneously by electrochemically reacting a fuel gas containing hydrogen and an oxidant gas containing oxygen such as air. It is.

  A fuel cell (unit cell) is configured by sandwiching a membrane electrode assembly (hereinafter referred to as MEA: Membrane-Electrode-Assembly) between a pair of plate-like conductive separators. The MEA is held at its peripheral edge (also referred to as an outer edge) by a resin frame formed into a frame shape in order to improve handling properties. Here, the MEA including the frame is referred to as an electrode-membrane-frame assembly.

  The MEA is composed of a polymer electrolyte membrane whose peripheral portion is supported by the frame, and a pair of electrode layers formed on both sides of the electrolyte membrane and disposed on the inner side of the frame. The pair of electrode layers includes a catalyst layer made of platinum or the like formed on both surfaces of the polymer electrolyte membrane and a porous and conductive gas diffusion layer formed on the catalyst layer. When fuel gas or oxidant gas is supplied to the pair of electrode layers, respectively, an electrochemical reaction occurs, and electric power and heat are generated.

  As a conventional method for producing an electrode-membrane-frame assembly, for example, there is one disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2011-40290). Patent Document 1 discloses that the gas diffusion layer is compressed by a protrusion provided on the mold for the purpose of controlling the penetration of the molding resin material into the gas diffusion layer and the catalyst layer.

JP 2011-40290 A

  The present inventors have used a gas diffusion layer composed of a porous member mainly composed of conductive particles and a polymer resin in order to realize both improvement in power generation performance and cost reduction of a fuel cell. The fuel cell that had been studied.

  However, in the production of a fuel cell using such a gas diffusion layer, the power generation performance and durability of the produced fuel cell are sufficiently ensured even if the conventional method for producing an electrode-membrane-frame assembly is applied. I couldn't.

  Accordingly, an object of the present invention is to solve the above-described problems, and to provide a method for manufacturing an electrode-membrane-frame assembly and a method for manufacturing a fuel cell that can further improve the power generation performance and durability of the fuel cell. It is to provide.

In order to achieve the above object, the present invention is configured as follows.
According to the present invention, there is provided a method for producing an electrode-membrane-frame assembly in which a frame body is formed on the periphery of a membrane electrode assembly in which a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of a polymer electrolyte membrane. ,
The protrusion provided on the inner surface of the mold is stabbed into the peripheral edge of the gas diffusion layer, and the molten resin material is poured into the mold in a state where movement in the surface direction of the gas diffusion layer is regulated. Injection molding the frame,
Including
The protrusions are formed with non-uniform height from the inner surface of the mold, or provided with a plurality of intermittently as viewed from the thickness direction of the mold,
When the membrane electrode assembly is viewed from the thickness direction of the mold when the movement of the gas diffusion layer is regulated,
A movement restricting region that is a region overlapping with the protruding portion;
A weak movement restricting region that is a region that overlaps a protruding portion that is lower in height or smaller in width than an adjacent protruding portion, or a region in which the protruding portion does not exist in a peripheral portion of the gas diffusion layer, Have
The movement restricting region is located in the vicinity of a gate for pouring the resin material provided in the mold;
A method for producing an electrode-membrane-frame assembly is provided.

  According to the method for manufacturing an electrode-membrane-frame assembly according to the present invention, the power generation performance and durability of the fuel cell can be further improved.

It is sectional drawing which shows typically the basic composition of the electrode-membrane-frame assembly manufactured by the manufacturing method of the electrode-membrane-frame assembly according to the first embodiment of the present invention. FIG. 2 is a plan view schematically showing the basic configuration of the electrode-membrane-frame assembly of FIG. 1. It is sectional drawing which shows typically the manufacturing method of the electrode-membrane-frame assembly concerning 1st Embodiment of this invention. It is sectional drawing which shows the process of following FIG. 3A. FIG. 3C is a cross-sectional view showing a step following FIG. 3B. It is a top view which shows typically the 1st metal mold | die used for the manufacturing method of the electrode-membrane-frame assembly concerning 1st Embodiment of this invention. It is A1-A1 sectional drawing of FIG. It is sectional drawing which shows typically the basic composition of a fuel cell provided with the electrode-membrane-frame assembly concerning 1st Embodiment of this invention, and is a figure which shows the example by which the gas flow path was provided in the separator. FIG. 7 is an exploded perspective view showing a basic configuration of a fuel cell stack in which a plurality of the fuel cells of FIG. 6 are connected. It is sectional drawing which shows typically the basic composition of a fuel cell provided with the electrode-membrane-frame assembly concerning 1st Embodiment of this invention, and is a figure which shows the example by which the gas flow path was provided in the gas diffusion layer. . It is a top view which shows typically the 3rd metal mold | die used for the manufacturing method of the electrode-membrane-frame assembly concerning 2nd Embodiment of this invention. It is a top view which shows typically the 4th metal mold | die used for the manufacturing method of the electrode-membrane-frame assembly concerning 3rd Embodiment of this invention. It is a top view which shows typically the 5th metal mold | die used for the manufacturing method of the electrode-membrane-frame assembly concerning 4th Embodiment of this invention. It is A2-A2 sectional drawing of FIG. It is an enlarged plan view which shows the example by which the projection part with high height from the inner surface of a 5th metal mold | die is arrange | positioned in the vicinity of the gate of a 5th metal mold | die. It is a top view which shows typically the 6th metal mold | die used for the manufacturing method of the electrode-membrane-frame assembly concerning 5th Embodiment of this invention. It is a top view which shows typically the electrode-membrane-frame assembly in which the rectangular annular protrusion trace was formed in the peripheral part of the gas diffusion layer. It is a top view which shows typically the electrode-membrane-frame assembly in which the some protrusion trace was intermittently formed in the peripheral part of the gas diffusion layer.

(Knowledge that became the basis of the present invention)
A gas diffusion layer composed of a porous member mainly composed of conductive particles and a polymer resin has lower porosity and lower rigidity than a gas diffusion layer having a base material such as carbon paper. It has the nature of As a result of diligent research, the present inventors have produced an electrode-membrane-frame assembly using a gas diffusion layer composed of a porous member mainly composed of conductive particles and a polymer resin. It has been found that the following problems due to properties occur.

  The injection molding is performed by placing the membrane electrode assembly in a mold, closing the mold, and pouring a molten resin material into the peripheral edge thereof. At this time, when the force with which the peripheral edge of the gas diffusion layer is pressed by the mold is weak, a phenomenon occurs in which the gas diffusion layer moves while sliding toward the center. Hereinafter, this phenomenon is referred to as a skid phenomenon. This skid phenomenon occurs for the following reason.

  That is, since the gas diffusion layer composed of a porous member mainly composed of conductive particles and a polymer resin has low porosity, the injected resin material is less likely to be impregnated into the gas diffusion layer. Therefore, when the resin material is injected from the side surface of the gas diffusion layer toward the gas diffusion layer, the gas diffusion layer is pushed toward the center by the injection pressure. In addition, since the gas diffusion layer composed of a porous member mainly composed of conductive particles and a polymer resin has low rigidity, the shape is likely to change. Accordingly, the gas diffusion layer slides toward the center while changing its shape.

  As a method for suppressing the side slip phenomenon, for example, a method in which a rectangular annular protrusion is provided on the inner surface of the mold and injection molding is performed in a state where the protrusion is pierced into the peripheral edge of the gas diffusion layer can be considered.

  However, in this method, as shown in FIG. 15, a rectangular annular protrusion mark 101 a to which the shape of the protrusion is transferred is formed at the peripheral edge of the gas diffusion layer 101. When a fuel cell is manufactured using the electrode-membrane-frame assembly in which the protrusion mark 101a is formed and a reaction gas is supplied into the fuel cell, the reaction gas flows into the protrusion mark 101a, and the gas flow It may happen that the fuel cell is discharged outside the fuel cell without flowing into the road. Hereinafter, this phenomenon is referred to as a gas wraparound phenomenon. When this gas sneak phenomenon occurs, the utilization efficiency of the reaction gas decreases, and the power generation performance of the fuel cell decreases.

  As a method for suppressing the gas wraparound phenomenon, for example, a method using a mold in which a plurality of protrusions are intermittently arranged in a rectangular ring shape can be considered. According to this method, as shown in FIG. 16, a plurality of protrusion traces 101a are intermittently formed on the peripheral portion of the gas diffusion layer 101, and the flow of the reaction gas flowing through the protrusion trace 101a is inhibited. , Gas wraparound phenomenon can be suppressed. Moreover, since the movement of the gas diffusion layer in the surface direction can be restricted by the plurality of protrusions, the side slip phenomenon can also be suppressed.

  However, in this method, the skid phenomenon can be suppressed, but the deformation of the gas diffusion layer cannot be sufficiently suppressed, and as a result, the inventors have found that the desired durability cannot be obtained. Therefore, the present inventors diligently studied and found that the cause of the deformation of the gas diffusion layer is the strength of the injection pressure near the gate for pouring the resin material into the mold. That is, the gas diffusion layer composed of a porous member mainly composed of conductive particles and a polymer resin has low porosity and is difficult to impregnate the injected resin material. The present inventors have found that the deformation occurs under the influence of the injection pressure stronger than the region in the other mold. Based on these findings, the present inventors have found that the desired durability can be obtained by sufficiently suppressing the deformation of the gas diffusion layer by devising the shape or arrangement of the protrusion near the gate. Invented.

According to the first aspect of the present invention, an electrode-membrane-frame assembly in which a frame body is formed on the peripheral edge of a membrane electrode assembly in which a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of a polymer electrolyte membrane. A method,
The protrusion provided on the inner surface of the mold is stabbed into the peripheral edge of the gas diffusion layer, and the molten resin material is poured into the mold in a state where movement in the surface direction of the gas diffusion layer is regulated. Injection molding the frame,
Including
The protrusions are formed with non-uniform height from the inner surface of the mold, or provided with a plurality of intermittently as viewed from the thickness direction of the mold,
When the membrane electrode assembly is viewed from the thickness direction of the mold when the movement of the gas diffusion layer is regulated,
A movement restricting region that is a region overlapping with the protruding portion;
A weak movement restricting region that is a region that overlaps a protruding portion that is lower in height or smaller in width than an adjacent protruding portion, or a region in which the protruding portion does not exist in a peripheral portion of the gas diffusion layer, Have
The movement restricting region is located in the vicinity of a gate for pouring the resin material provided in the mold;
A method for producing an electrode-membrane-frame assembly is provided.

  According to the second aspect of the present invention, the gas diffusion layer is composed of a porous member mainly composed of conductive particles and a polymer resin, and the electrode-membrane-frame joint according to the first aspect. A method for manufacturing a body is provided.

According to the third aspect of the present invention, an electrode-membrane-frame assembly in which a frame is formed on the peripheral edge of a membrane electrode assembly in which a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of a polymer electrolyte membrane; A method of manufacturing a fuel cell having a pair of separators sandwiching the electrode-membrane-frame assembly,
The protrusion provided on the inner surface of the mold is stabbed into the peripheral edge of the gas diffusion layer, and the molten resin material is poured into the mold in a state where movement in the surface direction of the gas diffusion layer is regulated. Injection molding the frame,
Including
The protrusions are formed with non-uniform height from the inner surface of the mold, or provided with a plurality of intermittently as viewed from the thickness direction of the mold,
When the membrane electrode assembly is viewed from the thickness direction of the mold when the movement of the gas diffusion layer is regulated,
A movement restricting region that is a region overlapping with the protruding portion;
A weak movement restricting region that is a region that overlaps a protruding portion that is lower in height or smaller in width than an adjacent protruding portion, or a region in which the protruding portion does not exist in a peripheral portion of the gas diffusion layer, Have
The movement restricting region is located in the vicinity of a gate for pouring the resin material provided in the mold;
A method for manufacturing a fuel cell is provided.

According to the fourth aspect of the present invention, a gas flow path is provided in at least one of the separator and the gas diffusion layer,
4. The fuel cell manufacturing method according to the third aspect, wherein a cross-sectional area of a protrusion trace formed by the protrusion projecting into the gas diffusion layer is smaller than a cross-sectional area of a gas flow channel located in the vicinity of the protrusion trace. Provide a method.

According to the fifth aspect of the present invention, a gas flow path is provided in at least one of the separator and the gas diffusion layer,
The weak movement restricting region overlaps with a gas supply region which is a portion to which a reaction gas is supplied to the gas flow path when the state in which the movement of the gas diffusion layer is restricted is viewed from the thickness direction of the mold. Located in at least one of the region overlapping with the gas discharge region, which is a region to discharge the reaction gas from the gas flow path,
A method for producing a fuel cell according to the third or fourth aspect is provided.

According to the sixth aspect of the present invention, at least one of the separator and the gas diffusion layer is provided with a gas flow path having a plurality of turn regions for reversing the flow direction of the reaction gas,
The weak movement restriction region is located in a turn adjacent region in the vicinity between the turn regions adjacent to each other when the state in which the movement of the gas diffusion layer is restricted is viewed from the thickness direction of the mold.
The manufacturing method of the fuel cell as described in any one of 3rd-5th aspect is provided.

  According to a seventh aspect of the present invention, the gas diffusion layer is composed of a porous member mainly composed of conductive particles and a polymer resin, according to any one of the third to sixth aspects. A fuel cell manufacturing method is provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all of the following drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted.

<< First Embodiment >>
Before describing the manufacturing method of the electrode-membrane-frame assembly according to the first embodiment of the present invention, the configuration of the electrode-membrane-frame assembly manufactured by the manufacturing method will be described. FIG. 1 is a cross-sectional view schematically showing a basic configuration of an electrode-membrane-frame assembly manufactured by the method for manufacturing an electrode-membrane-frame assembly according to the first embodiment, and FIG. It is a top view.

  An electrode-membrane-frame assembly 1 manufactured by the method for manufacturing an electrode-membrane-frame assembly according to the first embodiment includes a MEA (membrane electrode assembly) 10 and a frame formed on the peripheral portion of the MEA 10. And a body 20.

  The MEA 10 includes a polymer electrolyte membrane 11 and a pair of electrode layers 12 and 12 formed on both surfaces of the polymer electrolyte membrane 11. One of the pair of electrode layers 12 is an anode electrode, and the other is a cathode electrode. The electrode layer 12 includes a catalyst layer 13 and a gas diffusion layer 14. The catalyst layer 13 is formed on the surface of the polymer electrolyte membrane 11, and the gas diffusion layer 14 is formed on the catalyst layer 13. That is, the catalyst layer 13 and the gas diffusion layer 14 are sequentially laminated on both surfaces of the polymer electrolyte membrane 11. As will be described in detail later, protrusion marks (mold marks) 14 a formed by protrusions provided on the mold are intermittently formed on the peripheral edge of the gas diffusion layer 14.

  The polymer electrolyte membrane 11 is larger in size than the catalyst layer 13 and the gas diffusion layer 14 and is provided so that the peripheral edge protrudes from them. The catalyst layer 13 may be the same size as the gas diffusion layer 14 or a larger size. A frame body 20 is provided so as to cover the protruding portion of the polymer electrolyte membrane 11. The shape of the frame 20 is not particularly limited, but in the first embodiment, it is a substantially rectangular ring.

  The polymer electrolyte membrane 11 is preferably a polymer membrane having hydrogen ion conductivity. The polymer electrolyte membrane 11 is not particularly limited. For example, a fluorine-based polymer electrolyte membrane made of perfluorocarbon sulfonic acid (for example, Nafion (registered trademark) manufactured by DuPont, USA, manufactured by Asahi Kasei Corporation) Aciplex (registered trademark), Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd.) and various hydrocarbon electrolyte membranes can be used. The material of the polymer electrolyte membrane 11 may be any material that selectively moves hydrogen ions. The shape of the polymer electrolyte membrane 11 is not particularly limited, but is substantially rectangular in the first embodiment.

  The catalyst layer 13 is preferably a layer containing a catalyst for a redox reaction of hydrogen or oxygen. The catalyst layer 13 is not particularly limited. For example, the catalyst layer 13 can be composed of a porous member mainly composed of carbon powder carrying a platinum-based metal catalyst and a polymer material having proton conductivity. . The catalyst layer 13 only needs to have conductivity and have a catalytic ability for a redox reaction of hydrogen and oxygen. The shape of the catalyst layer 13 is not particularly limited, but is substantially rectangular in the first embodiment. The catalyst layer 13 can be formed by coating or spraying a catalyst layer forming ink on the surface of the polymer electrolyte membrane 11.

  The gas diffusion layer 14 is configured by a so-called base material-less gas diffusion layer configured without using carbon fiber as a base material. Specifically, the gas diffusion layer 14 is composed of a porous member mainly composed of conductive particles and a polymer resin. Here, the “porous member mainly composed of conductive particles and polymer resin” means a structure (so-called self-supporting structure) that is supported only by conductive particles and polymer resin without using carbon fiber as a base material. It means a porous member having a support structure. When producing a porous member with conductive particles and a polymer resin, for example, a surfactant and a dispersion solvent are used. In this case, during the production process, the surfactant and the dispersion solvent are removed by firing, but they may not be sufficiently removed and may remain in the porous member. Therefore, as long as the “porous member mainly composed of conductive particles and polymer resin” has a self-supporting structure in which carbon fiber is not used as a base material, the surfactant and the dispersion remaining in this manner are dispersed. It means that a solvent may be included in the porous member. In addition, if the self-supporting structure does not use carbon fibers as a base material, it means that other materials (for example, carbon fibers of short fibers) may be included in the porous member.

  The gas diffusion layer 14 can be manufactured by kneading, extruding, rolling, and firing a mixture containing a polymer resin and conductive particles. Specifically, carbon, which is conductive particles, a dispersion solvent, and a surfactant are introduced into a stirrer / kneader, and then kneaded, pulverized, and granulated to disperse the carbon in the dispersed solvent. Next, the fluororesin, which is a polymer resin, is further dropped into a stirrer / kneader and stirred and kneaded to disperse the carbon and the fluororesin. The obtained kneaded material is rolled to form a sheet and fired to remove the dispersion solvent and the surfactant. Thereby, the sheet-like gas diffusion layer 14 can be manufactured.

  Examples of the material of the conductive particles constituting the gas diffusion layer 14 include carbon materials such as graphite, carbon black, and activated carbon. Examples of the carbon black include acetylene black (AB), furnace black, ketjen black, vulcan, and the like. These materials may be used alone, or a plurality of materials may be used in combination. . In addition, the raw material form of the carbon material may be any shape such as powder, fiber, and granule.

  Materials for the polymer resin constituting the gas diffusion layer 14 include PTFE (polytetrafluoroethylene), FEP (tetrafluoroethylene / hexafluoropropylene copolymer), PVDF (polyvinylidene fluoride), ETFE (tetrafluoroethylene). -Ethylene copolymer), PCTFE (polychlorotrifluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer) and the like. Among these, PTFE is preferably used as the polymer resin material from the viewpoints of heat resistance, water repellency, and chemical resistance. Examples of the raw material form of PTFE include dispersion and powder. Among these, it is preferable from the viewpoint of workability that a dispersion is adopted as a raw material form of PTFE. The polymer resin constituting the gas diffusion layer 14 has a function as a binder for binding the conductive particles. Further, since the polymer resin has water repellency, it also has a function (water retention) for confining water in the system inside the fuel cell.

  Further, as described above, the gas diffusion layer 14 may contain a trace amount of a surfactant and a dispersion solvent used in the production of the cathode gas diffusion layer in addition to the conductive particles and the polymer resin. Examples of the dispersion solvent include water, alcohols such as methanol and ethanol, and glycols such as ethylene glycol. Examples of the surfactant include nonionic compounds such as polyoxyethylene alkyl ethers and zwitterionic compounds such as alkylamine oxides. What is necessary is just to set suitably the quantity of the dispersion solvent used at the time of manufacture, and the quantity of surfactant according to the kind of electroconductive particle, the kind of polymer resin, those compounding ratios, etc. In general, as the amount of the dispersion solvent and the amount of the surfactant increases, the polymer resin and the conductive particles tend to be uniformly dispersed, but the fluidity increases and the sheet of the gas diffusion layer is increased. It tends to be difficult. The surfactant can be appropriately selected depending on the material of the conductive particles and the type of the dispersion solvent. Moreover, it is not necessary to use a surfactant.

  In addition, the gas diffusion layer 14 may use a gas diffusion layer having the same structure or a gas diffusion layer having a different structure on the cathode electrode side and the anode electrode side. For example, a gas diffusion layer using carbon fiber as a base material may be used on either the cathode electrode side or the anode electrode side, and the base material-less gas diffusion layer may be used on either side.

  As a material of the frame body 20, a general thermoplastic resin, a thermosetting resin, or the like can be used. For example, as a material of the frame 20, silicon resin, epoxy resin, melamine resin, polyurethane resin, polyimide resin, acrylic resin, ABS resin, polypropylene, liquid crystalline polymer, polyphenylene sulfide resin, polysulfone, glass fiber reinforced resin, etc. Can be used.

  Next, a method for manufacturing the electrode-membrane-frame assembly according to the first embodiment will be described. 3A to 3C are explanatory views schematically showing a method for manufacturing the electrode-membrane-frame assembly according to the first embodiment. FIG. 4 is a plan view schematically showing a first mold used in the method for producing a membrane-catalyst layer assembly according to the first embodiment of the present invention. 5 is a cross-sectional view taken along line A1-A1 of FIG.

  In the manufacturing method according to the first embodiment, the first mold T1 and the second mold T2 are used as the molds. As shown in FIG. 4, the first mold T1 is provided with a plurality of gates T1b for pouring molten resin material into the mold. Further, as shown in FIGS. 4 and 5, a plurality of protrusions T1a for pressing the peripheral edge are provided on the inner surface of the first mold T1. The plurality of protrusions T1a are intermittently disposed in a rectangular ring shape and are disposed in the vicinity of each gate T1b. Similarly, a plurality of protrusions T2a for pressing the peripheral edge are provided on the inner surface of the second mold T1. The plurality of projecting portions T2a are intermittently disposed in a rectangular ring shape, similarly to the projecting portion T1a, and are disposed in the vicinity of the gate T1b.

  First, as shown in FIG. 3A, the MEA 10 is disposed in the second mold T2 such that the protrusion T2a of the second mold T2 pierces the peripheral edge of one gas diffusion layer 14. Thereby, the movement of the gas diffusion layer 14 of the MEA 10 in the surface direction (lateral direction in FIG. 3A) is restricted. The “peripheral portion” mainly refers to a gas diffusion layer when the electrode-membrane-frame assembly 1 is mounted on a fuel cell and viewed from the thickness direction of the electrode-membrane-frame assembly 1. 14 means an area located in the vicinity of the end of 14.

  Next, as shown in FIG. 3B, the first mold T1 and the second mold T2 are closed so that the protrusion T1a of the first mold T1 pierces the peripheral edge of the other gas diffusion layer 14.

  Next, as shown in FIG. 3C, the molten resin material is introduced into the space between the first mold T1 and the second mold T2 (that is, in the mold) through the gate T1b provided in the first mold T1. The frame 20 is injected and molded. At this time, even if the gas diffusion layer 14 receives injection pressure from its side surface, it is canceled by the projections T1a and T2a that are buried in the gas diffusion layer 14, so that the gas diffusion layer 14 slides toward the center. Can be prevented. Further, since the projecting portions T1a and T2a are disposed in the vicinity of the gate T1b, it is possible to suppress deformation of the gas diffusion layer 14 due to the strong injection pressure in the vicinity of the gate T1b.

  In the above description, the protrusions are provided on both the first mold T1 and the second mold T2. However, the protrusions may be provided on only one of them. Even in this case, the side slip and deformation of the gas diffusion layer 14 can be sufficiently suppressed.

  In the above description, the gate is provided in the first mold T1, but the gate may be provided in the second mold T2. In the above description, a plurality of gates are provided, but one gate may be provided. In this case, the plurality of protrusions T1a and T2a need not be intermittently provided, and may be provided only in the vicinity of the gate.

  Next, a fuel cell (unit cell) 2 including the electrode-membrane-frame assembly 1 according to the first embodiment will be described. FIG. 6 is a cross-sectional view schematically showing a basic configuration of a fuel cell 2 including the electrode-membrane-frame assembly 1 according to the first embodiment.

  As shown in FIG. 6, the fuel cell 2 is configured such that the electrode-membrane-frame assembly 1 is sandwiched between a pair of separators 30 and 40. The pair of separators 30 and 40 is preferably made of a material containing carbon or a material containing metal. A gas flow path 31 for fuel gas is provided on a main surface (hereinafter also referred to as an electrode surface) of one separator (anode separator) 30 that contacts the gas diffusion layer 14. A gas channel 41 for oxidizing gas is provided on the main surface (hereinafter also referred to as electrode surface) of the other separator (cathode separator) 40 that contacts the gas diffusion layer 14. By supplying the fuel gas to the gas flow path 31 of one separator 30 and supplying the oxidant gas to the gas flow path 41 of the other separator 40, an electrochemical reaction occurs, and electric power and heat are generated.

  When the fuel cell 2 is used as a power source, the required number of fuel cells (unit cells) 2 shown in FIG. 6 can be connected in series and used as a so-called fuel cell stack. In this case, in order to supply the reaction gas (fuel gas or oxidant gas) to the gas flow paths 31 and 41, the reaction gas is branched into a number corresponding to the number of separators 30 and 40 to be used, and the branch destinations thereof. Is required to connect the gas flow paths 31 and 41 to each other.

  FIG. 7 is an exploded perspective view showing a basic configuration of a fuel cell stack 3 in which a plurality of fuel cells 2 are connected. As shown in FIG. 7, the frame 20 and the pair of separators 30 and 40 are provided with fuel gas manifold holes 22, 32 and 42, which are a pair of through holes to which fuel gas is supplied, respectively. The frame 20 and the pair of separators 30 and 40 are provided with oxidant gas manifold holes 23, 33, and 43, which are a pair of through holes through which the oxidant gas flows. In a state where the frame 20 and the pair of separators 30 and 40 are connected as the fuel cell (unit cell) 2, the fuel gas manifold holes 22, 32, and 42 are connected to form a fuel gas manifold. Similarly, in a state where the frame 20 and the pair of separators 30 and 40 are connected as the fuel cell (unit cell) 2, the oxidant gas manifold holes 23, 33 and 43 are connected to form an oxidant gas manifold. The

  The frame body 20 and the pair of separators 30 and 40 are provided with cooling medium manifold holes 24, 34, and 44, which are two pairs of through holes, respectively, through which a cooling medium (for example, pure water or ethylene glycol) flows. Yes. In a state where the frame 20 and the pair of separators 30 and 40 are connected as the fuel cell (unit cell) 2, the cooling medium manifold holes 24, 34 and 44 are connected to form two pairs of cooling medium manifolds.

  The frame body 20 and the pair of separators 30 and 40 are provided with four bolt holes 50 in the vicinity of each corner. A fastening bolt is inserted into each bolt hole 50, and a plurality of fuel cells 2 are fastened by coupling a nut to the fastening bolt.

  The gas flow path 31 is provided so as to connect the pair of fuel gas manifolds 32, 32. The gas flow path 41 is provided so as to connect the pair of oxidant gas manifolds 43, 43. In addition, in FIG. 7, although the gas flow paths 31 and 41 were shown as a serpentine type flow path, the flow path of another form (for example, linear type) may be sufficient.

  Moreover, although not shown in figure, the cooling medium flow path is formed in the main surface on the opposite side to the electrode surface of the separator 30, and the main surface on the opposite side to the electrode surface of the separator 40, respectively. The cooling medium flow path is formed so as to connect the two pairs of cooling medium manifold holes 34 and 44. That is, the cooling medium is configured to branch from the cooling medium manifold on the supply side to the cooling medium flow path and to flow to the cooling medium manifold on the discharge side. Thus, the fuel cell 2 is maintained at a predetermined temperature suitable for the electrochemical reaction by utilizing the heat transfer capability of the cooling medium.

  In the above description, the manifolds for the fuel gas, the oxidant gas, and the cooling water are provided in the separators 30 and 40, and the supply manifolds for the fuel gas, the oxidant gas, and the cooling water are formed when they are stacked. The so-called internal manifold type fuel cell configured as described above has been described as an example, but the present invention is not limited to this. For example, a so-called external manifold type fuel cell in which supply manifolds of fuel gas, oxidant gas, and cooling water are provided on the side surface of the fuel cell stack 3 may be used. Even in this case, the same effect can be obtained. Further, the separators 30 and 40 are formed of a porous conductive material, and cooling is performed so that the pressure of the cooling water flowing through the cooling medium flow path is higher than the pressure of the reaction gas flowing through the gas flow paths 31 and 41. A so-called internal humidification type fuel cell in which a part of water is allowed to pass through the separators 30 and 40 to the electrode surface side to wet the polymer electrolyte membrane 11 may be used.

  In the above description, the gas flow paths 31 and 41 are provided in the separators 30 and 40. However, the present invention is not limited to this. For example, as shown in FIG. 8, the gas flow path 31 may be provided in one gas diffusion layer 14 and the gas flow path 41 may be provided in the other gas diffusion layer 14. Further, the gas flow path 31 may be formed in both the separator 30 and the one gas diffusion layer 14. Further, the gas flow path 41 may be formed in both the separator 40 and the other gas diffusion layer 14.

  As described above, according to the method for manufacturing the electrode-membrane-frame assembly according to the first embodiment, the protrusions T1a and T2a are pierced into the peripheral portion of the gas diffusion layer 14 and moved in the surface direction of the gas diffusion layer 14. Since the frame body 20 is injection-molded in a restricted state, it is possible to prevent the gas diffusion layer 14 from slipping. Further, by using a mold in which a plurality of protrusions T1a and T2a are intermittently arranged, the protrusion marks 14a are intermittently formed on the peripheral edge portion of the gas diffusion layer 14. It is possible to inhibit the flow of the reactive gas and suppress the phenomenon of gas wraparound. Furthermore, since the protrusions T1a and T2a are disposed in the vicinity of the gate T1b, it is possible to suppress deformation of the gas diffusion layer 14 due to the strong injection pressure in the vicinity of the gate T1b. Therefore, according to the manufacturing method of the electrode-membrane-frame assembly according to the first embodiment, the power generation performance and durability of the fuel cell can be further improved.

  In addition, the cross-sectional area of the protrusion trace 14a formed by the protrusion T1a of the first mold T1 or the protrusion T2a of the second mold T2 is the cross-sectional area of the gas flow paths 31 and 41 located in the vicinity of the protrusion trace 14a. It is preferable to make it smaller. Thereby, it becomes difficult for the reactive gas to flow into the protrusion mark 14a, and the phenomenon of gas wraparound can be further suppressed. The cross-sectional area of the protrusion mark 14a is preferably 75% or less, more preferably 50% or less, and further preferably 25% or less of the cross-sectional area of the gas flow path 31 located in the vicinity of the protrusion mark 14a. The gas flow path 31 located in the vicinity of the projection mark 14a is a gas flow located closest to the projection mark 14a when the fuel cell 2 is viewed from the thickness direction (vertical direction in FIG. 6 or FIG. 8). The roads 31 and 41 are meant.

<< Second Embodiment >>
A method for producing the electrode-membrane-frame assembly according to the second embodiment of the present invention will be described. The manufacturing method of the second embodiment is different from the manufacturing method of the first embodiment in that a third mold T3 is used instead of the first mold T1. FIG. 9 is a plan view schematically showing a third mold T3 used in the method for manufacturing the electrode-membrane-frame assembly according to the second embodiment. A one-dot chain line in FIG. 9 indicates a position where the gas flow path 31 corresponds (overlaps) when the third mold T3 is disposed on the electrode-membrane-frame assembly 1 in the thickness direction. . The gate T3b is provided at the same position as the gate T1b.

  In the vicinity of a gas supply region E1 (see FIG. 7) that is a portion where the reaction gas is supplied to the gas flow path 31 and / or a gas discharge region E2 (see FIG. 7) that is a portion that discharges the reaction gas from the gas flow path 31 If there are projection marks on the surface, the above-described gas wraparound phenomenon is likely to occur.

  Therefore, in the third mold T3, as shown in FIG. 9, in the area E1a overlapping with the gas supply area E1 and in the area E2a overlapping with the gas discharge area E2 when viewed from the thickness direction of the third mold T3. Is not provided with the protrusion T3a. By using the third mold T3 having such a projection T3a, it is possible to prevent projection traces from being formed in the vicinity of the gas supply region E1 and the gas discharge region E2. As a result, the gas wraparound phenomenon can be suppressed, and the power generation performance of the fuel cell can be improved.

  In the above description, the protrusion T3a is not provided in both the area E1 and the area E2. However, the protrusion T3a is not provided only in either the area E1 or the area E2. Also good. Even in this case, the gas wraparound phenomenon can be suppressed as compared with the manufacturing method of the first embodiment.

  In the above description, the third mold T3 is used instead of the first mold T1, but the third mold T3 may be used instead of the second mold T2. Further, the third mold T3 may be used in place of both the first mold T1 and the second mold T2.

<< Third Embodiment >>
A method for manufacturing the electrode-membrane-frame assembly according to the third embodiment of the present invention will be described. The manufacturing method of the third embodiment is different from the manufacturing method of the second embodiment in that a fourth mold T4 is used instead of the third mold T3. FIG. 10 is a plan view schematically showing a fourth mold T4 used in the method for manufacturing an electrode-membrane-frame assembly according to the third embodiment. The one-dot chain line in FIG. 10 indicates the position where the gas flow path 31 corresponds (overlaps) when the state in which the fourth mold T4 is disposed on the electrode-membrane-frame assembly 1 is viewed from the thickness direction. . The gate T4b is provided at the same position as the gate T1b.

  As shown in FIG. 10, when the gas flow path 31 is a serpentine type flow path, there are a plurality of turn regions E31 for reversing the flow direction of the reaction gas flowing through the gas flow path 31. If there is a protrusion trace in a region E31a (hereinafter referred to as a turn adjacent region) in the vicinity between the turn regions E31 and E31 adjacent to each other, it is possible that the reactive gas may shortcut the turn regions E31 and E31 adjacent to each other. That is, the reactive gas may flow linearly between the adjacent turn regions E31 and E31 without flowing in a meandering manner along the gas flow path 31. In this case, the utilization efficiency of the reaction gas is lowered, and the power generation performance of the fuel cell is lowered.

  Therefore, the fourth mold T4 is not provided with the protrusion T4a not only in the region E1a and the region E2a but also in the turn adjacent region E31a. By using the fourth mold T4 having such a protrusion T4a, it is possible to prevent a protrusion mark from being formed in the vicinity of the gas supply region E1, the gas discharge region E2, and the turn adjacent region E31a. Thereby, it is possible to suppress the phenomenon of gas wraparound and to suppress the occurrence of shortcuts. Therefore, the power generation performance of the fuel cell can be further improved.

  In the above description, the protrusion T4a is not provided in the region E1 and the region E2. However, the protrusion T3a may not be provided only in the turn adjacent region E31a. In this case, the occurrence of shortcuts can be suppressed, and the power generation performance of the fuel cell can be further improved compared to the manufacturing method of the first embodiment.

<< 4th Embodiment >>
A method for manufacturing the electrode-membrane-frame assembly according to the fourth embodiment of the present invention will be described. The manufacturing method of the fourth embodiment is different from the manufacturing method of the first embodiment in that a fifth mold T5 is used instead of the first mold T1. FIG. 11 is a plan view schematically showing a fifth mold T5 used in the method for manufacturing an electrode-membrane-frame assembly according to the fourth embodiment. 12 is a cross-sectional view taken along line A2-A2 of FIG. The gate T5c is provided at the same position as the gate T1b.

  From the viewpoint of preventing the gas diffusion layer 14 from slipping, it is preferable that the protrusions of the mold are formed continuously. For this reason, the fifth mold T5 has a protrusion T5a having a high height from the inner surface of the fifth mold T5 (shown by a dotted line in FIG. 12) and a height from the inner surface of the fifth mold T5. Protrusions T5b are alternately and continuously provided. In other words, the protruding portion of the fifth mold T5 is provided in an annular shape, and the height from the inner surface of the fifth mold T5 is uneven. Further, as shown in FIG. 13, the protrusion T5a having a high height from the inner surface of the fifth mold T5 is disposed in the vicinity of the gate T5c. By using the fifth mold T5 having such protrusions T5a and T5b, it is possible to further prevent the gas diffusion layer 14 from slipping compared to the manufacturing method of the first embodiment. Further, it is possible to further suppress the deformation of the gas diffusion layer 14 due to the influence of the strong injection pressure near the gate T5c.

  In addition, in FIG. 12, although the top part of the projection part of the 5th metal mold | die T5 was shown as a rectangular wave shape, this invention is not limited to this. For example, the top of the protrusion of the fifth mold T5 may be sinusoidal, triangular, or sawtooth.

<< 5th Embodiment >>
A method for producing an electrode-membrane-frame assembly according to a fifth embodiment of the present invention will be described. The manufacturing method of the fifth embodiment is different from the manufacturing method of the fourth embodiment in that a sixth mold T6 is used instead of the fifth mold T5. FIG. 14 is a plan view schematically showing a sixth mold T6 used in the method for manufacturing the electrode-membrane-frame assembly according to the fifth embodiment. The gate T6c is provided at the same position as the gate T5c.

  The sixth mold T6 is provided with protrusions T5a having a large width and protrusions T5b having a small width alternately and continuously. In other words, the protrusion of the sixth mold T6 is provided in an annular shape and is formed with an uneven width. In addition, the protruding portion T6a having a large width is disposed so as to be positioned in the vicinity of the gate T6c. By using the sixth mold T6 having such protrusions T6a and T6b, it is possible to further prevent the gas diffusion layer 14 from slipping compared to the manufacturing method of the first embodiment. Further, it is possible to further suppress the deformation of the gas diffusion layer 14 due to the influence of the strong injection pressure near the gate T6c.

  Note that the heights of the protrusions T6a and T6b from the inner surface of the sixth mold T6 may be the same or different.

  The present invention is not limited to the above-described embodiments, and can be implemented in various other modes. For example, although the cross section of each protrusion is illustrated as a rectangle, other shapes such as a triangle, a trapezoid, and a pentagon may be used.

  In addition, by appropriately combining any of the various embodiments, the effects possessed by them can be produced. For example, in the third mold T3 described in the second embodiment, the protrusion having a low height described in the fourth embodiment is provided in a region where the protrusion T3a is not provided (including the region E1 and the region E2). T5b may be provided. Thereby, it is possible to suppress the gas sneaking phenomenon and to further prevent the side diffusion of the gas diffusion layer 14.

  In this specification, when the state in which the MEA 10 is restricted from moving in the surface direction of the gas diffusion layer 14 by the protrusions is seen from the thickness direction of the mold, the MEA 10 overlaps with the high protrusions. The region is referred to as a “movement restriction region”, and a region that overlaps a protrusion having a low height or a region where no protrusion exists on the peripheral edge of the gas diffusion layer 14 is referred to as a “weak movement restriction region”.

  The method for manufacturing a membrane-electrode-frame assembly according to the present invention can further improve the power generation performance and durability of a fuel cell. For example, a mobile body such as an automobile, a distributed power generation system, and a household cogeneration system This is useful as a method for producing a membrane-catalyst layer assembly provided in a fuel cell used as a drive source for a system or the like.

DESCRIPTION OF SYMBOLS 1 Electrode-membrane-frame assembly 2 Fuel cell 3 Fuel cell stack 10 MEA (membrane electrode assembly)
DESCRIPTION OF SYMBOLS 11 Polymer electrolyte membrane 12 Electrode layer 13 Catalyst layer 14 Gas diffusion layer 14a Protrusion trace 20 Frame body 30, 40 Separator 31, 41 Gas flow path T1-T6 1st-6th metal mold T1a-T5a, T5b, T6a, T6b Projection T1b, T3b, T4b, T5c, T6c Gate

Claims (7)

A method for producing an electrode-membrane-frame assembly in which a frame body is formed on the peripheral edge of a membrane electrode assembly in which a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of a polymer electrolyte membrane,
The protrusion provided on the inner surface of the mold is stabbed into the peripheral edge of the gas diffusion layer, and the molten resin material is poured into the mold in a state where movement in the surface direction of the gas diffusion layer is regulated. Injection molding the frame,
Including
The protrusions are formed with non-uniform height from the inner surface of the mold, or provided with a plurality of intermittently as viewed from the thickness direction of the mold,
When the membrane electrode assembly is viewed from the thickness direction of the mold when the movement of the gas diffusion layer is regulated,
A movement restricting region that is a region overlapping with the protruding portion;
A weak movement restricting region that is a region that overlaps a protruding portion that is lower in height or smaller in width than an adjacent protruding portion, or a region in which the protruding portion does not exist in a peripheral portion of the gas diffusion layer, Have
The movement restricting region is located in the vicinity of a gate for pouring the resin material provided in the mold;
A method for producing an electrode-membrane-frame assembly.   The method for producing an electrode-membrane-frame assembly according to claim 1, wherein the gas diffusion layer is composed of a porous member mainly composed of conductive particles and a polymer resin. An electrode-membrane-frame assembly in which a frame body is formed on the periphery of a membrane electrode assembly in which a catalyst layer and a gas diffusion layer are sequentially laminated on both surfaces of the polymer electrolyte membrane, and the electrode-membrane-frame assembly is sandwiched A method of manufacturing a fuel cell having a pair of separators,
The protrusion provided on the inner surface of the mold is stabbed into the peripheral edge of the gas diffusion layer, and the molten resin material is poured into the mold in a state where movement in the surface direction of the gas diffusion layer is regulated. Injection molding the frame,
Including
The protrusions are formed with non-uniform height from the inner surface of the mold, or provided with a plurality of intermittently as viewed from the thickness direction of the mold,
When the membrane electrode assembly is viewed from the thickness direction of the mold when the movement of the gas diffusion layer is regulated,
A movement restricting region that is a region overlapping with the protruding portion;
A weak movement restricting region that is a region that overlaps a protruding portion that is lower in height or smaller in width than an adjacent protruding portion, or a region in which the protruding portion does not exist in a peripheral portion of the gas diffusion layer, Have
The movement restricting region is located in the vicinity of a gate for pouring the resin material provided in the mold;
Manufacturing method of fuel cell. At least one of the separator and the gas diffusion layer is provided with a gas flow path,
4. The fuel cell production according to claim 3, wherein a cross-sectional area of a protrusion trace formed by the protrusion projecting into the gas diffusion layer is smaller than a cross-sectional area of a gas flow channel located in the vicinity of the protrusion trace. Method. At least one of the separator and the gas diffusion layer is provided with a gas flow path,
The weak movement restricting region overlaps with a gas supply region which is a portion to which a reaction gas is supplied to the gas flow path when the state in which the movement of the gas diffusion layer is restricted is viewed from the thickness direction of the mold. Located in at least one of the region overlapping with the gas discharge region, which is a region to discharge the reaction gas from the gas flow path,
The manufacturing method of the fuel cell of Claim 3 or 4. At least one of the separator and the gas diffusion layer is provided with a gas flow path having a plurality of turn regions for reversing the flow direction of the reaction gas,
The weak movement restriction region is located in a turn adjacent region in the vicinity between the turn regions adjacent to each other when the state in which the movement of the gas diffusion layer is restricted is viewed from the thickness direction of the mold.
The manufacturing method of the fuel cell as described in any one of Claims 3-5.   The method of manufacturing a fuel cell according to any one of claims 3 to 6, wherein the gas diffusion layer is composed of a porous member mainly composed of conductive particles and a polymer resin.

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