JP2013037932A - Method for manufacturing electrode-membrane-frame assembly, and method for manufacturing fuel cell - Google Patents

Abstract

An electrode-membrane-frame assembly manufacturing method capable of further improving the power generation performance and durability of a fuel cell is provided.
A protrusion provided on the inner surface of a mold with a sharp tip is pierced into the peripheral portion of the gas diffusion layer, and the movement of the gas diffusion layer in the surface direction is regulated, and the mold is placed in the mold. The molten resin material is poured into the frame to be injection molded.
[Selection] Figure 3C

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. ,
A protrusion provided on the inner surface of the mold with a sharp tip is pierced into the peripheral edge of the gas diffusion layer and melted in the mold in a state where movement in the surface direction of the gas diffusion layer is restricted. Pour resin material and injection mold the frame,
A method for producing an electrode-membrane-frame assembly.

  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 with the manufacturing method of the membrane-catalyst layer assembly concerning embodiment of this 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 membrane-catalyst layer assembly concerning 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 membrane-catalyst layer assembly concerning embodiment of this invention. It is an expanded sectional view showing typically the state where the projection part provided in the 1st metallic mold of Drawing 4 was stuck in the gas diffusion layer. It is sectional drawing which shows typically the basic composition of a fuel cell provided with the electrode-membrane-frame assembly concerning 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 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 sectional drawing which shows the 1st modification of the projection part provided in a metal mold | die. It is sectional drawing which shows the 2nd modification of the projection part provided in a metal mold | die. It is sectional drawing which shows the state which has arrange | positioned the membrane electrode assembly to the metal mold | die which has a protrusion part of a rectangular cross section on the inner surface. It is the elements on larger scale of FIG.

(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, if the force that 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 referred to as “side slip”). 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.

  Next, a problem that occurs when the peripheral portion of the gas diffusion layer is strongly pressed by the mold during injection molding will be described with reference to FIGS. 10 and 11. FIG. 10 is a cross-sectional view showing a state in which the membrane electrode assembly is disposed in a mold having a rectangular cross-section protrusion on the inner surface. FIG. 11 is a partially enlarged view of FIG.

  As shown in FIG. 10, when the electrode-membrane assembly 102 is disposed on the mold 101 having the protrusion 101a having a rectangular cross section on the inner surface, the periphery of the gas diffusion layer 121 is strongly pressed by the protrusion 101a. Thereby, the above-mentioned side slip can be prevented. However, at this time, as shown in FIG. 11, the polymer electrolyte membrane 123 positioned below the protrusion 101a is also compressed and mechanically damaged. This is due to the following reason.

  That is, the gas diffusion layer 121 composed of a porous member mainly composed of conductive particles and polymer resin has low porosity and low rigidity. Therefore, the force applied to the gas diffusion layer 121 from the thickness direction (vertical direction in FIG. 10) is not easily dispersed as a force in the plane direction (lateral direction in FIG. 10), and is easily transmitted below the gas diffusion layer 121.

  When the gas diffusion layer 121 is pressed and compressed by the protrusion 101a, the force is transmitted to the gas diffusion layer 121, the catalyst layer 122, and the polymer electrolyte membrane 123 located below the protrusion 101a. For this reason, the polymer electrolyte membrane 123 positioned below the protrusion 101a is compressed and mechanically damaged. When the polymer electrolyte membrane 123 is mechanically damaged, deterioration of the portion is accelerated during power generation. As a result, the power generation performance and durability of the fuel cell are lowered.

  As described above, when the electrode-membrane-frame assembly is manufactured using the gas diffusion layer 121 composed of the porous member mainly composed of the conductive particles and the polymer resin, the gas diffusion layer 121 It has been difficult to achieve a balance between preventing side slip and not causing mechanical damage to the polymer electrolyte membrane 123.

  Based on this knowledge, the present inventors diligently studied, and thought that the above-mentioned problems could be solved by devising the shape of the protrusions of the mold, leading to the present invention.

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,
A protrusion provided on the inner surface of the mold with a sharp tip is pierced into the peripheral edge of the gas diffusion layer and melted in the mold in a state where movement in the surface direction of the gas diffusion layer is restricted. Pour resin material and injection mold the frame,
A method for producing an electrode-membrane-frame assembly.

  Note that Patent Document 1 described above discloses that the shape of the protrusion of the mold may be a semicircle, a triangle, a quadrangle, a trapezoid, or the like. However, the mold protrusion used in the manufacturing method of Patent Document 1 is provided for the purpose of compressing the gas diffusion layer in order to control the intrusion of the molded resin material into the gas diffusion layer and the catalyst layer. is there. For this reason, the shape of the protrusion part of the metal mold | die of patent document 1 needs to be a shape which can compress a gas diffusion layer. That is, even when the shape of the protrusion of the mold of Patent Document 1 is a triangle, the triangle needs to be an obtuse angle triangle whose apex angle is closer to 180 ° than 90 °, for example.

  On the other hand, the protrusion of the mold according to the first aspect of the present invention compresses the portion of the gas diffusion layer located below the protrusion as much as possible in order to avoid the polymer electrolyte membrane from being mechanically damaged. Without any problem, it is provided for the purpose of regulating the movement of the gas diffusion layer. For this reason, the protrusion part of the metal mold | die concerning the 1st aspect of this invention is made into the shape where the front-end | tip part was sharp, and is different from the protrusion part of patent document 1. FIG.

  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 a third aspect of the present invention, there is provided the method for producing an electrode-membrane-frame assembly according to the first aspect, wherein the height of the protrusion is less than the thickness of the gas diffusion layer.

  According to a fourth aspect of the present invention, in the electrode-membrane-frame assembly according to the third aspect, the height of the protrusion is not less than 50% and less than 95% of the thickness of the gas diffusion layer. A manufacturing method is provided.

  According to the 5th aspect of this invention, the manufacturing method of the electrode-membrane-frame assembly as described in any one of the 1st-4th aspect whose cross-sectional shape of the said protrusion part is a triangle is provided.

  According to a sixth aspect of the present invention, there is provided the method for producing an electrode-membrane-frame assembly according to any one of the first to fifth aspects, wherein an apex angle of the protrusion is 90 ° or less.

  According to a seventh aspect of the present invention, there is provided the method for producing an electrode-membrane-frame assembly according to any one of the first to fifth aspects, wherein an apex angle of the protrusion is 45 ° or less.

  According to an eighth aspect of the present invention, in the electrode-membrane-frame according to any one of the first to seventh aspects, the protrusion is provided in an annular shape when viewed from the thickness direction of the mold. A method for producing a joined body is provided.

According to the ninth aspect of the present invention, 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; A method of manufacturing a fuel cell having a pair of separators sandwiching the electrode-membrane-frame assembly,
A protrusion provided on the inner surface of the mold with a sharp tip is pierced into the peripheral edge of the gas diffusion layer and melted in the mold in a state where movement in the surface direction of the gas diffusion layer is restricted. Pour resin material and injection mold the frame,
The manufacturing method of a fuel cell including this is provided.

According to the tenth aspect of the present invention, a gas flow path is provided in at least one of the separator and the gas diffusion layer,
The fuel cell manufacturing according to the ninth 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.

  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.

<Embodiment>
Before describing the method for producing an electrode-membrane-frame assembly according to an embodiment of the present invention, the configuration of the electrode-membrane-frame assembly produced by the production 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 electrode-membrane-frame assembly manufacturing method according to the present embodiment, and FIG. 2 is a plan view thereof. It is.

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

  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, a protrusion mark (mold mark) 14 a formed by a protrusion provided on the mold is 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 present 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 this 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 approximately rectangular in this 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, the manufacturing method of the electrode-membrane-frame assembly according to the present embodiment will be described. 3A to 3C are explanatory views schematically showing a method for manufacturing the electrode-membrane-frame assembly according to the present embodiment.

  In the manufacturing method according to the present embodiment, the first mold T1 and the second mold T2 are used as molds. On the inner surface of the first mold T1, there is provided a protrusion T1a for pressing the peripheral edge with a sharp tip (wedge shape). The protrusion T1a is formed in an annular shape as shown in FIG. Similarly, the inner surface of the second mold T1 is provided with a peripheral edge pressing protrusion T2a having a sharp tip. The protrusion T2a is formed in an annular shape, like the protrusion T1a. The first mold T1 is provided with a gate T1b for pouring the molten resin material into the mold. The gate may be provided in the second mold T2.

  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. At this time, the protrusion T1a of the first mold T1 presses the gas diffusion layer 14 so as to be separated as indicated by the arrows in FIG. That is, the compressive force of the protrusion T1a against the gas diffusion layer 14 is mainly applied to the side of the protrusion T1a and hardly applied below the protrusion T1a. As a result, the polymer electrolyte membrane 11 can be prevented from being mechanically damaged. In the gas diffusion layer 14, the porosity of the portion located around the protrusion T1a is low, and the porosity of the portion located below the tip of the protrusion T1a is higher than that around the protrusion T1a. . Note that the plurality of black circles shown in FIG. 5 are given for convenience in order to show the difference in density, and the more black circles, the higher the density. Porosity is proportional to the inverse of density. “High porosity” corresponds to “low density” and “low porosity” corresponds to “high density”. In the above description, the pressing force applied by the projection T1a of the first mold T1 to the gas diffusion layer 14 has been described. The same applies to the pressing force applied by the projection T2a of the second mold T2 to the gas diffusion layer 14. The explanation is omitted because it exists.

  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 an injection pressure from its side surface, the injection pressure is canceled by the projections T1a and T2a existing in the gas diffusion layer 14, so that the gas diffusion layer 14 has its center It is possible to prevent a skidding toward the part.

  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 gas diffusion layer 14 can be prevented from sliding.

  Next, a fuel cell (unit cell) 2 including the electrode-membrane-frame assembly 1 according to the present 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 present 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 340. 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.

  Next, a preferable shape, height, and cross-sectional area of the protrusion T1a of the first mold T1 will be described. In addition, since the preferable shape, height, and cross-sectional area of the projection part T2a of the 2nd metal mold | die T2 are the same as that of the projection part T1a of the 1st metal mold | die T1, description is abbreviate | omitted.

  The protrusion T1a may have any shape that does not reduce the porosity of the portion of the gas diffusion layer 14 located below the tip of the protrusion T1a when stabbed into the gas diffusion layer 14. Examples of the shape of the projection T1a include a triangle as shown in FIG. 5, a pentagon as shown in FIG. 9A, and a shape obtained by slightly rounding the tip of the triangle as shown in FIG. 9B.

  Further, as the apex angle θ of the protrusion T1a is reduced, the porosity of the portion of the gas diffusion layer 14 located below the tip end of the protrusion T1a can be suppressed. For this reason, the apex angle θ of the protrusion T1a is preferably 90 ° or less, and more preferably 45 ° or less. Further, the apex angle θ of the protrusion T1a is more preferably 30 ° or less, and particularly preferably 15 ° or less.

  Further, the height of the protrusion T1a is preferably less than the thickness of the gas diffusion layer 14. Thereby, it can prevent that protrusion part T1a penetrates the gas diffusion layer 14, and is pierced by the polymer electrolyte membrane 11. FIG. Here, the thickness of the gas diffusion layer 14 refers to the thickness of the gas diffusion layer 14 in a state where the first mold T1 and the second mold T2 are closed. Further, the height of the protrusion T1a is preferably 95% or less of the thickness of the gas diffusion layer 14 in consideration of manufacturing variations of the gas diffusion layer 14.

  Further, the height of the protrusion T1a is preferably 50% or more of the thickness of the gas diffusion layer 14, and more preferably 75% or more. Thereby, the side slip of the gas diffusion layer 14 can be prevented more reliably. In addition, since the molten resin can be prevented from flowing into the inner region that contributes to the power generation of the gas diffusion layer 14 by the protrusion T1a, a decrease in the power generation performance of the fuel cell 2 can be suppressed.

  Moreover, it is preferable to make the cross-sectional area of the protrusion trace 14a formed by the protrusion T1a smaller than the cross-sectional area of the gas flow path 31 shown in FIG. The reason is as follows.

  As shown in FIGS. 1 and 2, a protrusion T <b> 1 a is formed at the peripheral portion of the gas diffusion layer 14 of the electrode-membrane-frame assembly 1 manufactured by the electrode-membrane-frame assembly manufacturing method of the present embodiment. A protrusion mark 14a having the shape transferred is formed. When the fuel cell 2 is manufactured using the electrode-membrane-frame assembly 1 in which the protrusion marks 14a are formed and the reaction gas is supplied into the fuel cell 2, the reaction gas flows into the protrusion marks 14a. It is possible that the fuel cell 2 is discharged to the outside without flowing into the gas flow path 31. Hereinafter, this phenomenon is referred to as a gas wraparound phenomenon. When this gas wraparound phenomenon occurs, the utilization efficiency of the reaction gas decreases, and the power generation performance of the fuel cell 2 decreases.

  In order to prevent this gas wraparound phenomenon, it is effective to make the cross-sectional area of the protrusion trace 14a smaller than the cross-sectional area of the gas flow path 31 located in the vicinity of the protrusion trace 14a. For this reason, 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). This means the road 31.

  As described above, according to the method for manufacturing the electrode-membrane-frame assembly according to the present embodiment, the protrusions T1a and T2a are pierced into the peripheral portion of the gas diffusion layer 14 to restrict movement in the surface direction of the gas diffusion layer 14. Since the frame body 20 is injection-molded in this state, it is possible to prevent the gas diffusion layer 14 from slipping and to prevent the polymer electrolyte membrane 11 from being mechanically damaged. Therefore, the power generation performance and durability of the fuel cell can be further improved.

  In addition, this invention is not limited to the said embodiment, It can implement in another various aspect.

  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, T2 1st, 2nd metal mold T1a, T2a Protrusion part T1b Gate

Claims (10)

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,
A protrusion provided on the inner surface of the mold with a sharp tip is pierced into the peripheral edge of the gas diffusion layer and melted in the mold in a state where movement in the surface direction of the gas diffusion layer is restricted. Pour resin material and injection mold the frame,
Manufacturing method of 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.   The method of manufacturing an electrode-membrane-frame assembly according to claim 1, wherein the height of the protrusion is less than the thickness of the gas diffusion layer.   The method of manufacturing an electrode-membrane-frame assembly according to claim 3, wherein the height of the protrusion is 50% or more and less than 95% of the thickness of the gas diffusion layer.   The method for producing an electrode-membrane-frame assembly according to any one of claims 1 to 4, wherein a cross-sectional shape of the protrusion is a triangle.   The method for producing an electrode-membrane-frame assembly according to any one of claims 1 to 5, wherein the protrusion has an apex angle of 90 ° or less.   The method for producing an electrode-membrane-frame assembly according to any one of claims 1 to 5, wherein the protrusion has an apex angle of 45 ° or less.   The method of manufacturing an electrode-membrane-frame assembly according to any one of claims 1 to 7, wherein the protrusion is provided in an annular shape when viewed from the thickness direction of the mold. 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,
A protrusion provided on the inner surface of the mold with a sharp tip is pierced into the peripheral edge of the gas diffusion layer and melted in the mold in a state where movement in the surface direction of the gas diffusion layer is restricted. Pour resin material and injection mold the frame,
The manufacturing method of a fuel cell including this. At least one of the separator and the gas diffusion layer is provided with a gas flow path,
10. The fuel cell manufacturing according to claim 9, wherein a cross-sectional area of a protrusion trace formed by the protrusion protruding 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.

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