JP2010262829A - Method of manufacturing fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a fuel cell, capable of effectively preventing forming of a region having no surface pressure in a power generation region and forming of a region having excessive surface pressure in a non-power generation region, as a result of defining spaces among a lamination site where a reinforcement film is laminated on a catalyst layer, a catalyst layer and a gas transmission layer. <P>SOLUTION: The manufacturing method consists of a first step of forming first catalyst layers 21, 31 on either side of an electrolyte membrane 1, arranging reinforcement films 8A, 8B at an exposed region 1' of a peripheral edge of the electrolyte membrane 1 and laminating its part on the first catalyst layers 21, 31 to form a lamination site, a second step of forming second catalyst layers 22, 32 at a space defined by ends of the lamination site of the reinforcement films 8A, 8B, and the first catalyst layers 21, 31, and forming a membrane electrode assembly 4 in which total thicknesses of the first catalyst layers and the second catalyst layers, respectively, are made not less than total thicknesses of the first catalyst layers and the reinforcement film of the lamination site, respectively, and the third step of forming a fuel cell 10 by arranging gas permeation layers 5A, 6A, 5B, 6B on either side of the membrane electrode assembly 4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a fuel cell having a reinforcing membrane between a gas permeable layer and an electrolyte membrane, which is the periphery of a catalyst layer.

  A fuel cell of a polymer electrolyte fuel cell has a membrane electrode assembly (MEA) formed from an ion-permeable electrolyte membrane and an anode-side and cathode-side catalyst layer sandwiching the electrolyte membrane. An electrode body (MEGA: Membrane Electrode & Gas Diffusion Layer Assembly) is formed from the membrane electrode assembly and the anode-side and cathode-side gas diffusion layers (GDL) sandwiching the membrane-electrode assembly, and a fuel gas or an oxidant is formed on the electrode body. A gas flow path layer made of a porous metal body for collecting gas and collecting electricity generated by an electrochemical reaction and a separator are arranged on both sides of the electrode body. In addition, the fuel cell in which the gas flow channel groove is formed in the separator is also a conventional one, and in this case, the metal porous body that becomes the gas flow channel layer is unnecessary. An actual fuel cell stack is formed by stacking and stacking a number of fuel cell cells according to required power.

  In the fuel cell described above, hydrogen gas or the like is provided as a fuel gas to the anode electrode, oxygen or air is provided as the oxidant gas to the cathode electrode, and each electrode has a unique gas flow path layer (or formed in a separator). The gas flows in the in-plane direction in the gas channel groove), and then the gas diffused in the gas diffusion layer is guided to the electrode catalyst layer to cause an electrochemical reaction.

  As a form of the gas diffusion layer described above, a gas diffusion layer composed of a diffusion layer base material and a current collecting layer (MPL: Micro Porous Layer) is generally known. In general, the catalyst layer has a smaller planar area (smaller planar area) than the electrolyte membrane, and a polymer material is reinforced in the exposed area around the catalyst layer where the electrolyte membrane is not covered with the catalyst layer. A membrane (or protective film) is provided, and a structure in which this reinforcing membrane is interposed between a diffusion layer substrate and an electrolyte membrane is common. By interposing the reinforcing membrane between the diffusion layer base material and the electrolyte membrane in the peripheral region of the catalyst layer, the electrolyte membrane (membrane electrode assembly) having the catalyst layer and the gas diffusion layer are in a high temperature atmosphere of about 100 to 130 ° C., for example. Below, when thermocompression bonding is performed with a compressive force of about 1 to 3 MPa (thermocompression conditions that do not affect the electrolyte membrane), fuzz protruding from the surface of the fibrous diffusion layer base material is prevented from piercing the electrolyte membrane. be able to.

  Further, in the fuel cell described above, a gasket for sealing a fluid such as a fuel gas and an oxidant gas supplied to the membrane electrode assembly, and a cooling water for suppressing the temperature rise of the cell, It is formed by injection molding or compression molding at the periphery of the body or porous metal body. For example, in a fuel cell having a metal porous body serving as a gas flow path, one metal porous body on the anode side or cathode side is accommodated in the cavity of the mold, and then the electrode body is accommodated, and then the anode side or Gasket molding is performed by injecting a resin into the gasket forming cavity at the periphery of the electrode body and the metal porous body in a posture in which the other metal porous body on the cathode side is accommodated. There is also a method in which either the anode side or the cathode side separator is first accommodated in the cavity, and then the above-described constituent members are accommodated for injection molding.

  Examples of the separator include a three-layer structure in which an intermediate plate in which a flow path is formed between two plates made of titanium or stainless steel, for example, or an intermediate layer made of a resin frame. There are a plurality of dimples and ribs that define a flow path project from one of the plates to form a cooling water flow path. The separator having the three-layer structure is either the anode side or the cathode side separator of the cell itself, and at the same time, is the other separator on the anode side or the cathode side of the adjacent cell in the stacked posture. That is, the cell constituent member of the fuel cell having this three-layer structure separator is composed of one three-layer structure separator and a gas permeable layer on the anode side and the cathode side (from a porous metal body such as expanded metal or metal foam sintered body). Gas passage layer) and an electrode body (membrane electrode assembly and gas diffusion layer), and in a posture in which a plurality of fuel cells are stacked, an arbitrary fuel cell has an anode side at both ends and It has a cathode side separator.

  FIG. 4 shows the structure of a conventional fuel cell having the above-described reinforcing membrane and gasket. Further, the surface pressure acting on the electrode body due to the compressive force at the time of stacking is further shown in FIG. Shown for each. In FIG. 4, a membrane electrode assembly c is formed from an electrolyte membrane a and cathode and anode catalyst layers b1 and b2, and the membrane electrode assembly c is formed into a cathode-side and anode-side gas diffusion layer d ( A diffusion layer base material d1 and a current collecting layer d2) are sandwiched and formed. The catalyst layers b1 and b2 are narrower than the electrolyte membrane a, and the cathode-side and anode-side reinforcing membranes e1 and e2 are disposed in the exposed regions where the electrolyte membrane a is not covered with the catalyst layers b1 and b2. These are interposed between the electrolyte membrane a and the diffusion layer base material d1. In the illustrated example, a metal porous body f serving as a gas flow path is provided on the cathode side and the anode side, and the periphery of the electrode body and the metal porous body f is injection-molded, and fluid circulation is provided in the inside thereof. A gasket g having a manifold M is formed.

  As in the illustrated example, the reinforcing membranes e1 and e2 generally have their catalyst layer side ends wrapped (laminated) on the catalyst layers b1 and b2. When the fluff of the diffusion layer base material pierces the electrolyte membrane a during thermocompression bonding, the reinforcing membranes e1 and e2 promote gas cross-leakage, and the cross-leak durability of the fuel cell decreases. It is provided in order to solve the problem of being directly linked to a decrease in power generation performance. In other words, the region where the electrolyte membrane a is in contact with the catalyst layers b1 and b2 is the region where the electrolyte membrane a is protected from fluff sticking by the catalyst layers b1 and b2, while the exposed region of the electrolyte membrane a described above. Are protected from fluff sticking by the reinforcing films e1 and e2. Here, in order to avoid the fluff from passing through the end portions of the catalyst layers b1 and b2 to the electrolyte membrane a, the end portions of the reinforcing membranes e1 and e2 are laminated on the catalyst layers b1 and b2, as shown in the figure. Yes. As a prior art exhibiting the laminated structure of the reinforcing membrane, a fuel cell disclosed in Patent Document 1 can be cited.

  In general, since the reinforcing membrane is higher in rigidity than the electrolyte membrane and the catalyst layer and has a relatively high hardness, the number of fluff penetrating through the reinforcing membrane is extremely small even when the above-mentioned fluff is pierced. As a result, it is effectively prevented that the fluff penetrates the anode side and the cathode side through the reinforcing membrane and the electrolyte membrane.

  By the way, the fuel cell stack is formed by stacking and stacking a plurality of fuel cells, and the compressive force at the time of stacking is transmitted to each fuel cell, and as shown in the drawing, it is applied to the membrane electrode assembly c. On the other hand, it acts as a compressive force P from above and below. Here, when the reinforcing membranes e1 and e2 are laminated with the catalyst layers b1 and b2, as shown in the figure, the electrode body portion A (the laminated portion of the reinforcing membrane) where the relatively rigid reinforcing membrane is laminated is relatively As a result, a large amount of compressive force is borne, resulting in a problem that the desired compressive force does not act on other electrode body locations.

  Alternatively, as shown in the surface pressure graph of FIG. 4, in the electrode body portion A in which the reinforcing film is laminated on the catalyst layer, the surface pressure is excessively high, and the region where the outer reinforcing film is present is the reinforcing film. However, since it is more rigid than an electrolyte membrane or the like, it becomes an overpressure region. On the other hand, the inside of the electrode body portion A has a portion G where the gas diffusion layer and the catalyst layer are not in contact with each other, so that no surface pressure acts on the electrode body portion corresponding to this portion G, and there is no surface pressure. A region is formed.

  In general, the inner side (including no surface pressure region) of this surface pressure non-region is the power generation region, and the outer surface pressure region outside the non-power generation region is a non-power generation region. Excessive surface pressure acts, which causes a problem that sufficient compression force does not act on the power generation region, and that no surface pressure region occurs as shown in the figure, which significantly reduces the power generation performance of the fuel cell. Being a factor is easy to understand.

JP 2008-71542 A

  The present invention has been made in view of the above-described problems, and is provided at the periphery of the catalyst layer, including a reinforcing film (for example, a protective film) between the gas permeable layer and the electrolyte film, and an end of the reinforcing film is provided. In a method of manufacturing a fuel cell comprising: a membrane electrode assembly laminated (wrapped) on a catalyst layer; and a gas permeable layer disposed on both sides of the membrane electrode assembly, the reinforcing membrane is formed on the catalyst layer. The stacking location where the layers are stacked excessively bears a relatively large proportion of the compressive force during stacking, and therefore, a problem that sufficient compressive force does not act on the power generation region, or A fuel cell that can effectively solve the problem that the surface pressure does not act on a part of the electrode body that should essentially be in the power generation region, and therefore the amount of power generation must be reduced. An object is to provide a manufacturing method.

  In order to achieve the above object, a method of manufacturing a fuel cell according to the present invention includes a membrane electrode assembly formed of an electrolyte membrane and a catalyst layer that has a smaller planar area than the catalyst layer and contacts both sides of the electrolyte membrane. A fuel cell manufacturing method in which gas permeable layers are disposed on both sides of the membrane electrode assembly, wherein a first catalyst layer is formed on both sides of the electrolyte membrane, and the first of the electrolyte membranes A first step, a reinforcing membrane, in which a reinforcing film is disposed in an exposed area on the periphery not covered with the catalyst layer, and a part of the reinforcing film is laminated on the first catalyst layer to form a laminated portion A second catalyst layer is formed in a space defined by the end portion of the stacked portion and the first catalyst layer, and the sum of the thicknesses of the first catalyst layer and the second catalyst layer is determined. A second step of forming a membrane / electrode assembly as a sum of the thicknesses of the first catalyst layer and the reinforcing membranes at the laminated portion, a gas A third step of forming a fuel cell by arranging an over layer on both sides of the membrane electrode assembly, is made of.

  In another embodiment of the method for producing a fuel cell according to the present invention, the first catalyst layer is formed on both sides of the electrolyte membrane, and the electrolyte membrane is not covered with the first catalyst layer. A reinforcing film is disposed in the exposed area of the periphery, and a part of the reinforcing film is laminated on the first catalyst layer to form a laminated portion. A second catalyst layer is formed at a position corresponding to the space defined by the end portion of the laminated portion of the membrane and the first catalyst layer, and the first catalyst layer and the second catalyst layer are applied to each other. The electrolyte membrane and the gas permeable layer are laminated through the catalyst layer so as to be in contact with each other, and the sum of the thicknesses of the first catalyst layer and the second catalyst layer is determined for each of the first catalyst layer and the reinforcing membrane of the laminated portion. The second step is to form the fuel cell as the sum of the thickness or more.

  The fuel cell manufactured by the manufacturing method of the present invention described above has a part of the reinforcing film stacked on the catalyst layer to form a stacked portion, and the catalyst layer is formed of a plurality of layers of two or more layers. A space formed by forming a laminated portion of the reinforcing film on the first catalyst layer in contact with the electrolyte membrane, and defining an end portion of the laminated portion of the reinforcing membrane and the first catalyst layer The second catalyst layer is formed and the space is closed by the catalyst layer, so that the problem of the fuel cell of the conventional structure, that is, the region where the reinforcing membrane exists is an overpressure region, The formation of a surface pressure-free region does not act on the power generation region where the gas permeable layer (gas diffusion layer) and the catalyst layer do not contact with each other, and the problem that the power generation performance may be reduced due to the formation of the surface pressure-free region is effective. It will be solved. A predetermined number of fuel cells manufactured by this manufacturing method are stacked and stacked to form a fuel cell (stack).

  Here, as an embodiment of the method for forming the second catalyst layer, the second catalyst layer may be directly formed on the surface (the space) of the first catalyst layer in contact with the electrolyte membrane. . That is, the first catalyst layer is formed on the surface of the electrolyte membrane, and then the reinforcing membrane is formed so as to be partially wrapped around the periphery of the first catalyst layer (formation of the laminated portion). The catalyst ink (catalyst solution) for the second catalyst layer is applied to the space defined by the end portion of the portion and the first catalyst layer, and dried, so that 2 catalyst layers are formed.

  Further, as another embodiment of the method of forming the second catalyst layer, for example, when a gas permeable layer such as a gas diffusion layer is hot pressed with an electrolyte membrane having the first catalyst layer on the surface thereof, The second catalyst layer was formed by forming the second catalyst layer at the surface position of the gas permeable layer corresponding to the space defined by the end of the laminated portion of the reinforcing membrane and the first catalyst layer. Even in a method of forming a catalyst layer in which the first catalyst layer and the second catalyst layer are laminated by hot pressing the gas permeable layer and the electrolyte membrane on which the first catalyst layer is formed. Good.

  Here, the reason why the catalyst layer is divided into the first catalyst layer and the second catalyst layer is because the manufacturing process and the base material formed are different. When the components of the catalyst (the catalyst material, the amount of catalyst supported, etc.) are the same, the first catalyst layer and the second catalyst layer can be an integral catalyst layer in the final contacted posture. Needless to say. In addition, the first catalyst layer and the second catalyst layer may have the same catalyst component (catalyst material, supported amount, etc.), or may be formed of different catalyst components. Furthermore, since the conventional structure has only one catalyst layer (corresponding to only the first catalyst layer here), the total amount of catalyst in the first and second catalyst layers is set to that of the conventional structure. By making it the same as the catalyst amount of one catalyst layer, it is possible to suppress an increase in the catalyst amount when two or more layers are formed.

  Each of the first and second catalyst layers may be composed of a plurality of catalyst layers, which means that three or more catalyst layers (third catalyst layer, fourth catalyst layer) In this way, even in a laminated structure of three or more layers, the sum of the thicknesses of the first catalyst layer to the nth catalyst layer (n ≧ 3) is the first. What is necessary is just to be more than the sum of the thickness of the reinforcing film of a catalyst layer and a lamination | stacking location.

  Furthermore, in the manufacturing method described above, the membrane electrode assembly is formed by setting the sum of the thicknesses of the first catalyst layer and the second catalyst layer to be equal to or greater than the sum of the thicknesses of the first catalyst layer and the reinforcing membranes at the laminated positions. Thus, for example, in a posture in which the compressive force at the time of stacking acts on the catalyst layer and the reinforcing film via the gas diffusion layer, it is possible to ensure that the compressive force acts on the entire surface of the catalyst layer, and the above-described surface pressure The formation of no area can be suppressed. This also means that it is possible to effectively prevent the compressive force during stacking from acting excessively (bearing excessive compressive force) on the laminated portion of the reinforcing membrane, and thus it is desirable for the power generation region. This leads to the application of the compression force.

  However, in view of the fact that the catalyst layer has low rigidity and a large amount of deformation with respect to the same compressive force as compared with the reinforcing membrane, the sum of the thicknesses of the first catalyst layer and the second catalyst layer can be calculated. It is preferable that the thickness is larger than the sum of the thicknesses of the first catalyst layer and the reinforcing film at the laminated portion.

  As described above, in the fuel cell manufacturing method of the present invention, a separate catalyst is formed in the space defined by the end portion of the laminated portion where the reinforcing membrane is laminated on the first catalyst layer and the first catalyst layer. A layer (second catalyst layer) is formed, and the thickness of all the catalyst layers in the region where the second catalyst layer is formed is extremely simple simply by forming it to a thickness greater than the thickness of the laminated portion of the reinforcing membrane. By the manufacturing method, a desired and uniform in-plane compressive force can be applied to the power generation region of the catalyst layer.

  Here, the structure of the fuel cell manufactured by the manufacturing method of the present invention is a mode in which a gas diffusion layer comprising a diffusion layer base material and a current collecting layer is provided on both the anode side and the cathode side of the membrane electrode assembly, Either one of the anode side and the cathode side includes both of the forms including only the current collecting layer (the diffusion layer base material is discarded). In the present specification, any of these forms is referred to as an electrode body. In addition to a configuration in which separators having gas flow channel grooves formed on both sides of the electrode body are directly arranged, a gas flow channel layer (a porous metal such as an expanded metal) is formed between a so-called flat type separator and the electrode body. Body) is included. Furthermore, the “gas permeable layer” is meant to include both a gas diffusion layer and a gas flow path layer. Therefore, in a cell configuration that does not include a gas flow path layer, a “gas permeable layer” means a “gas diffusion layer”, and in a cell configuration that includes both a gas diffusion layer and a gas flow path layer, The “permeation layer” means either or both of “gas diffusion layer” and “gas flow path layer”.

  The separator has a three-layer structure as described above, that is, a first plate (for example, cathode side plate), an intermediate layer (or intermediate plate), and a second plate (for example, anode side plate) are laminated. It may have a separator having a three-layer structure, or may have a conventional general separator in which a gas groove channel is formed on one side surface and a cooling medium groove channel is formed on the other side surface. Good.

  Note that the second catalyst layer described above may be formed only on either the anode side or the cathode side, in addition to the form provided on both the anode side and the cathode side. Well, even in this configuration, it is possible to effectively relieve the excessive surface pressure that may occur in the non-power generation region, as compared with the conventional structure in which a space is formed between the gas permeable layer and the catalyst layer at both poles. It is possible to suppress formation of a pressureless region and an overpressure region.

  As can be understood from the above description, according to the method of manufacturing a fuel cell of the present invention, at least a reinforcing membrane is interposed between the exposed region of the peripheral edge of the electrolyte membrane not covered with the catalyst layer and the gas permeable layer. And a part of the reinforcing membrane is laminated on the (first) catalyst layer to form a laminated portion, the end of the laminated portion of the reinforcing membrane, the (first) catalyst layer, By closing the space defined by a separate (second) catalyst layer, it is possible to effectively suppress an excessive surface pressure from acting on the peripheral region that becomes the non-power generation region, and the central power generation region Thus, a desired surface pressure can be reliably applied. This leads to an improvement in the power generation performance of the fuel cell and an increase in the amount of power generation.

It is the longitudinal cross-sectional view which showed a part of one Embodiment of the fuel cell manufactured by the manufacturing method of this invention, Comprising: It is the figure which showed the state which the compression force acted on the stacking. It is the longitudinal cross-sectional view which showed a part of other embodiment of the fuel cell manufactured by the manufacturing method of this invention, Comprising: It is the figure which showed the state which the compression force at the time of stacking acted. It is the longitudinal cross-sectional view which showed a part of further another embodiment of the fuel cell manufactured by the manufacturing method of this invention, Comprising: It is the figure which showed the state which the compression force at the time of stacking acted. It is the longitudinal cross-sectional view which showed a part of fuel cell of the conventional structure, Comprising: It is the figure which showed together the surface pressure which acts on an electrode body by the compressive force at the time of stacking.

  Embodiments of the present invention will be described below with reference to the drawings. Although the illustrated example shows a cell structure in which a reinforcing film is disposed on both the cathode side and the anode side, a through-hole penetrating the electrolyte membrane due to fluff sticking out from the gas diffusion layer is not formed. As a premise, a cell structure in which a reinforcing film is disposed only on one of the anode side and the cathode side may be used.

  1 to 3 are longitudinal sectional views showing a part of a fuel battery cell manufactured by the manufacturing method of the present invention. In the fuel cell 10 shown in FIG. 1, a membrane electrode assembly 4 is formed from the electrolyte membrane 1 and the catalyst layers 2 and 3 on the cathode side and the anode side, and this is formed into a gas diffusion layer 5A on the cathode side and the anode side. , 5B (gas permeable layer) sandwiched to form an electrode body, cathode side and anode side gas flow path layers 6A, 6B (gas permeable layer) are arranged on both sides of the electrode body, and gas flow path layer 6A, A separator 7 having a three-layer structure is disposed on one side of 6B, and a gasket 9 made of a resin material is formed on the periphery of the electrode body and the gas flow path layers 6A and 6B. In the posture in which a plurality of illustrated fuel cells 10 are stacked and stacked, the electrode body and the gas flow path layers 6A and 6B are composed of their own separators 7 and the separators 7 of adjacent fuel cells in the stacked posture. It becomes a sandwiched structure.

  Here, the catalyst layers 2 and 3 have a smaller area than the electrolyte membrane 1, and therefore the catalyst layers 2 and 3 do not exist at the periphery of the catalyst layers 2 and 3 on both sides of the electrolyte membrane 1. An exposed region 1 ′ is formed.

  In the exposed region 1 ′, reinforcing films 8A and 8B on the cathode side and the anode side are arranged. More specifically, a part of the reinforcing films 8A and 8B is wrapped on the catalyst layers 2 and 3. Thus, the reinforcing films 8A and 8B are arranged from the catalyst layers 2 and 3 to the exposed region 1 ′ in a posture in which stacked portions are formed. By arranging the reinforcing films 8A and 8B in a posture in which the laminated portion is formed, it is possible to completely prevent the fluff protruding from the gas diffusion layers 5A and 5B from being stuck into the electrolyte membrane 1.

  Here, the electrolyte membrane 1 constituting the membrane electrode assembly 4 is, for example, a fluorine ion exchange membrane having a sulfonic acid group or a carbonyl group, a substituted phenylene oxide, a sulfonated polyaryletherketone, a sulfonated polyarylethersulfone, It is formed from a non-fluorine polymer such as sulfonated phenylene sulfide.

  Here, the catalyst layers 2 and 3 are formed directly on the surface of the electrolyte membrane 1, and the first catalyst layers 21 and 31 in which a part of the reinforcing membranes 8A and 8B are laminated, and the reinforcing membranes 8A and 8B. And the second catalyst layers 22 and 32 for closing the space defined by the first catalyst layers 21 and 31.

Here, the manufacturing method of the illustrated fuel cell 10 will be outlined.
First, in a container (not shown), a conductive carrier (such as a particulate carbon carrier) on which a catalyst such as platinum or a platinum alloy is supported, and an electrolyte made of Nafion (registered trademark, manufactured by DuPont), A catalyst solution is produced by mixing a dispersion solvent (organic solvent) such as ethanol or propylene glycol. Here, the dispersion of the electrolyte is performed using various mills, ultrasonic dispersers, or the like. The catalyst solution produced by this method is used to form both the cathode side and the anode side catalyst layers (that is, the bipolar catalyst layers are produced with the catalyst solution of the same material).

  The produced catalyst solution is poured onto the electrolyte membrane 1, and the catalyst solution is stretched in layers by a coating blade (not shown) to form an anode-side coating film. A first catalyst layer 31 is formed.

  Here, the electrolyte membrane 1 is a fluorine-based ion exchange membrane having a sulfonic acid group or a carbonyl group, a non-fluorine-based material such as a substituted phenylene oxide, a sulfonated polyaryletherketone, a sulfonated polyarylethersulfone, or a sulfonated phenylene sulfide. It is formed from such a polymer. In addition, the formation method of a coating film is not limited to this method, Conventionally well-known formation methods, such as spray coating, the inkjet method, and the screen printing method, are applicable.

  When the anode-side first catalyst layer 31 is formed on one surface of the electrolyte membrane 1, a catalyst solution of the same material as the anode side is flowed to the other surface of the electrolyte membrane 1, and the cathode-side first catalyst layer 31 is subjected to the same manufacturing method. The catalyst layer 21 is formed. The formation order of the first catalyst layers 31 and 21 may be reversed.

Next, reinforcing membranes 8A and 8B made of polyethylene naphthalate (PEN) are partially wrapped with the first catalyst layers 31 and 21, and an adhesive or the like is interposed on the surface of the exposed region 1 ′ of the electrolyte membrane. By arranging these, a space defined by the first catalyst layers 31 and 21 and the end portions of the laminated portions of the reinforcing membranes 8A and 8B is formed. FIG. 1 is a longitudinal sectional view showing only the right side of the fuel cell 10, and it goes without saying that a similar structure is formed on the left side.
A catalyst solution made of the same material as that of the first catalyst layers 31 and 21 is poured into a space defined by the first catalyst layers 31 and 21 and end portions of the laminated portions of the reinforcing films 8A and 8B. By forming the second catalyst layers 32 and 22 in the same manner as the first catalyst layers 31 and 21, the catalyst layer 2 on the cathode side on which the two catalyst layers are laminated as shown in the drawing, the anode side The catalyst layer 3 can be formed.

  In forming the catalyst layer, the thickness of the central power generation region (the region where the second catalyst layers 22 and 32 are formed) and the peripheral edge in the posture shown in FIG. The first catalyst layer 21 and the second catalyst are previously set so that the thickness of the non-power generation region (region in which the second catalyst layers 22 and 32 are not formed) is approximately the same thickness: t. The sum of the thicknesses of the layers 22 (the sum of the thicknesses of the first catalyst layer 31 and the second catalyst layer 32) is formed to be thicker than the sum of the thicknesses of the first catalyst layer 21 and the reinforcing membrane 8A. Good.

  In general, the catalyst layers 2 and 3 have a lower rigidity than the reinforcing membranes 8A and 8B, and a large amount of deformation with respect to the compressive force takes into account the central power generation region in a state before stacking. By adjusting the thickness of the catalyst layer to be a predetermined amount larger than the thickness of the non-power generation region, the compressive force at the time of stacking acts, and the catalyst layers 2 and 3 and the reinforcing membranes 8A and 8B have their own deformations. In the final posture deformed by the amount, the thickness of the catalyst layer in the central power generation region and the thickness obtained by adding the reinforcing films 8A and 8B to the thickness of the catalyst layer in the peripheral non-power generation region can be made comparable.

  When the membrane / electrode assembly 4 is formed, the gas diffusion layers 5A and 5B are sequentially pressed on both sides of the membrane / electrode assembly 4 at a predetermined pressure in a predetermined high-temperature atmosphere to thereby connect the membrane / electrode assembly 4 and the gas diffusion layers 5A and 5B. Thermocompression bonding.

Finally, the separator 7 having the three-layer structure, the anode-side gas flow path layer 6B, the electrode body, and the cathode-side gas flow path layer 6A are accommodated in the mold, and the mold is closed. The gasket 9 is formed by a method such as injection of resin into the other gasket cavity (injection molding).
In addition to the above method, the second catalyst layers 22 and 32 are formed on the surfaces of the gas diffusion layers 5A and 5B at positions corresponding to the spaces described above, and the first catalyst layers 21 and 31 are formed. The first catalyst layers 21 and 31 and the second catalyst layers 22 and 32 are brought into contact with the electrolyte membrane 1 formed with the gas diffusion layers 5A and 5B formed with the second catalyst layers 22 and 32. A method of thermocompression bonding in a different posture may be used.

  Here, it demonstrates in detail about the raw material of each component of the fuel cell 10 mentioned above. First, as an electrolyte for forming a catalyst solution, an ion exchange resin having an organic fluorine-containing polymer as a skeleton, which is a proton conductive polymer, for example, a perfluorocarbon sulfonic acid resin, a sulfonated polyether ketone, a sulfonated polyether. Sulfonated plastic electrolytes such as sulfone, sulfonated polyetherethersulfone, sulfonated polysulfone, sulfonated polysulfide, sulfonated polyphenylene, sulfoalkylated polyetheretherketone, sulfoalkylated polyethersulfone, sulfoalkylated polyetherethersulfone And sulfoalkylated plastic electrolytes such as sulfoalkylated polysulfone, sulfoalkylated polysulfide, and sulfoalkylated polyphenylene. Examples of commercially available materials include Nafion (registered trademark, manufactured by DuPont) and Flemion (registered trademark, manufactured by Asahi Glass Co., Ltd.).

  Examples of the dispersion solvent include alcohols such as methanol, ethanol, 1-propanol, 2-propanol, ethylene glycol, and diethylene glycol, acetone, methyl ethyl ketone, dimethylformamide, dimethylimidazolidinone, dimethyl sulfoxide, dimethylacetamide, and N-methylpyrrolidone. , Propylene carbonate, esters such as ethyl acetate and butyl acetate, and various aromatic or halogen solvents, and these can be used alone or as a mixed solution. Furthermore, regarding a conductive carrier carrying a catalyst, examples of the conductive carrier include carbon materials such as carbon black, carbon nanotubes, and carbon nanofibers, and carbon compounds typified by silicon carbide. As this catalyst (metal catalyst), for example, any one of platinum, platinum alloy, palladium, rhodium, gold, silver, osmium, iridium, etc. can be used, preferably platinum or platinum alloy is used. It is good to do. Furthermore, as this platinum alloy, for example, platinum, aluminum, chromium, manganese, iron, cobalt, nickel, gallium, zirconium, molybdenum, ruthenium, rhodium, palladium, vanadium, tungsten, rhenium, osmium, iridium, titanium and lead An alloy with at least one of them can be mentioned.

  The gas diffusion layers 5A and 5B are composed of diffusion layer base materials 51a and 51b and current collection layers 52a and 52b. The diffusion layer base materials 51a and 51b have low electrical resistance and can collect current. If it is, it will not specifically limit, For example, what mainly has an electroconductive inorganic substance can be mentioned, As this electroconductive inorganic substance, the baking body from a polyacrylonitrile, the baking body from a pitch, Examples thereof include carbon materials such as graphite and expanded graphite, nanocarbon materials thereof, stainless steel, molybdenum, titanium, and the like. Further, the form of the conductive inorganic substance of the diffusion layer base materials 51a and 51b is not particularly limited, and for example, it is used in the form of fibers or particles, but is an inorganic conductive fiber from the viewpoint of gas permeability, Carbon fiber is particularly preferable. As the diffusion layer substrate using inorganic conductive fibers, a woven fabric or non-woven fabric structure can be used, and examples thereof include carbon paper and carbon cloth. The woven fabric is not particularly limited, such as plain weaving, crest weaving, and binding weaving, and examples of the nonwoven fabric include those made by a papermaking method, a needle punching method, and a water jet punching method. Further, examples of the carbon fiber include phenol-based carbon fiber, pitch-based carbon fiber, polyacrylonitrile (PAN) -based carbon fiber, and rayon-based carbon fiber. Further, the current collecting layers 52a and 52b serve as electrodes for collecting electrons from the catalyst layers 3 and 2 on the anode side and the cathode side, and have a water repellent action for draining generated water and the like. It can be formed from platinum, palladium, ruthenium, rhodium, iridium, gold, silver, copper and their compounds or alloys, a conductive carbon material, and a fluororesin (PTFE).

  Further, the gas flow path layers 6A and 6B are formed of a porous metal body such as expanded metal or a metal fired sintered body, and the fired sintered body is excellent in corrosion resistance such as titanium, stainless steel, copper, and nickel. Further, a metal material may be used, and a foam in which chromium carbide or iron-chromium carbide is dispersed in stainless steel may be used.

  Further, the reinforcing films 8A and 8B are made of polytetrafluoroethylene, PVDF (polyvinyl difluoride), polyethylene, polyethylene naphthalate (PEN), polycarbonate, polyphenylene ether (PPE), polypropylene, polyester, polyamide, copolyamide, polyamide elastomer. , Polyimide, polyurethane, polyurethane elastomer, silicone, silicone rubber, silicon-based elastomer, and the like.

  The gasket 9 has an endless rib (not shown) surrounding the manifold M on the periphery of the manifold M at the end thereof. As a material of this gasket, an epoxy resin having methanol resistance and an epoxy-modified silicone are used. Resin, silicone resin, fluorine resin, urethane RTV rubber, butyl rubber resin, silicone RTV rubber, EPDM resin, and the like can be used.

  The separator 7 having a three-layer structure includes a cathode side plate 71 and an anode side plate 72 made of stainless steel or titanium, and an intermediate layer in which a flow path for a cooling medium such as cooling water is formed between a metal material or a resin material. 73 (intermediate plate) is interposed. The separator 7 includes a gas flow path (not shown) for supplying fuel gas to the gas flow path layer 6B on the anode side of the fuel cell, which is a constituent element, and a cathode of an adjacent cell in the cell stacking posture. A gas flow path (not shown) for supplying an oxidant gas to the gas flow path layer 6A on the side is formed, and further, the above-described cooling medium flow path (not shown) is formed.

  As shown in FIG. 1, according to the fuel cell 10 manufactured by the above-described manufacturing method, the thickness of the power generation region in the center of the catalyst layers 2 and 3 in the posture in which the compression force P during stacking is applied, The thickness of the non-power generation region at the periphery of the catalyst layers 2 and 3 (the sum of the thicknesses of the laminated portions of the catalyst layer and the reinforcing film on the periphery) is approximately the same, and a space in the central power generation region as in the conventional structure is formed. There is nothing. For this reason, there is a risk that a surface pressureless region is formed in the power generation region, and that a surface pressure region is not formed in the non-power generation region, so that a sufficient surface pressure does not act on the power generation region. Both are effectively eliminated, and a given compressive force can be uniformly applied to the power generation region in the plane.

  The fuel cell 10A shown in FIG. 2 has a power generation region thickness: t1 thicker than a non-power generation region thickness: t in a posture in which compression force P during stacking is applied. The second catalyst layers 22 </ b> A and 32 </ b> A are formed by making them thicker than the second catalyst layers 22 and 32 of the fuel cell 10. In the illustrated example, the catalyst layers 2A and 3A are formed from the second catalyst layers 22A and 32A and the first catalyst layers 21 and 31, and the membrane electrode assembly 4A is formed from the catalyst layers 2A and 3A and the electrolyte membrane 1. Is formed.

  The fuel cell 10B shown in FIG. 3 has a structure in which the second catalyst layer is eliminated from the anode-side catalyst layer from the configuration of the fuel cell 10 shown in FIG. 1, that is, in this membrane electrode assembly 4B. The anode-side catalyst layer 3 ′ is formed only from the first catalyst layer.

  Also in this embodiment, at least in the cathode side electrode, the thickness of both the central power generation region and the peripheral non-power generation region of the catalyst layer 2 is approximately the same, and there is no space in the power generation region as in the conventional structure shown in FIG. Thus, an excessive surface pressure that can occur in the non-power generation region is suppressed as compared with the fuel cell of the conventional structure.

  Of course, the structure of the catalyst layer shown in FIG. 3 may be reversed between the anode side and the cathode side. Further, in the structure of FIG. 3, the anode side reinforcing film 8B may be further eliminated. However, in that case, it is necessary to ensure that only the reinforcing film 8A on the cathode side does not form a through-hole penetrating the electrolyte membrane 1 due to fluff sticking from the gas diffusion layers 5A and 5B.

  In an actual fuel cell, the fuel cell shown in FIGS. 1 to 3 is stacked in a predetermined stage to form a fuel cell stack. Further, in the fuel cell stack, a terminal plate, an insulating plate, and an end plate are arranged on the outermost side, and a compressive force is applied through a tension plate to form a fuel cell. A fuel cell system mounted on an electric vehicle or the like includes this fuel cell, various tanks for storing hydrogen gas and air, a blower for supplying these gases to the fuel cell, a radiator for cooling the fuel cell, a fuel The battery is generally composed of a battery that stores electric power generated by the battery, a drive motor that is driven by the electric power, and the like.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like without departing from the gist of the present invention. They are also included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane, 1 '... Exposed area | region of electrolyte membrane, 2, 2A ... Cathode side catalyst layer, 21 ... 1st catalyst layer, 22, 22A ... 2nd catalyst layer, 3, 3A, 3' ... Anode Catalyst layer on the side, 31 ... first catalyst layer, 32, 32A ... second catalyst layer, 4,4A, 4B ... membrane electrode assembly, 5A ... gas diffusion layer (gas permeable layer) on the cathode side, 5B ... Gas diffusion layer (gas permeable layer) on the anode side, 6A ... Gas channel layer on the cathode side (gas permeable layer), 6B ... Gas channel layer on the anode side (gas permeable layer), 7 ... Separator, 71 ... Cathode side Plate, 72 ... Anode side plate, 73 ... Intermediate layer (intermediate plate), 8A ... Reinforcing membrane on the cathode side, 8B ... Reinforcing membrane on the anode side, 9 ... Gasket, 10, 10A, 10B ... Fuel cell

Claims (4)

A fuel in which a membrane electrode assembly is formed from an electrolyte membrane and a catalyst layer abutting on both sides of the electrolyte membrane with a smaller plane area than this, and gas permeable layers are arranged on both sides of the membrane electrode assembly A battery cell manufacturing method comprising:
Forming a first catalyst layer on both sides of the electrolyte membrane, disposing a reinforcing membrane in an exposed region of the peripheral edge of the electrolyte membrane not covered with the first catalyst layer, and a part of the reinforcing membrane; A first step of laminating on the first catalyst layer to form a laminated portion;
A second catalyst layer is formed in a space defined by the end of the laminated portion of the reinforcing membrane and the first catalyst layer, and the thickness of each of the first catalyst layer and the second catalyst layer is A second step of forming a membrane electrode assembly by setting the sum to be equal to or greater than the sum of the thicknesses of the first catalyst layer and the reinforcing membrane at the stacking portion,
A fuel cell manufacturing method comprising a third step of forming a fuel cell by disposing a gas permeable layer on both sides of the membrane electrode assembly. A membrane electrode assembly is formed from an electrolyte membrane and a catalyst layer that is in contact with both sides of the electrolyte membrane with a smaller plane area than this, and a gas permeable layer is disposed on both sides of the membrane electrode assembly to provide a fuel cell A method of manufacturing a fuel cell comprising a cell and the fuel cell being stacked,
Forming a first catalyst layer on both sides of the electrolyte membrane, disposing a reinforcing membrane in an exposed region of the peripheral edge of the electrolyte membrane not covered with the first catalyst layer, and a part of the reinforcing membrane; A first step of laminating on the first catalyst layer to form a laminated portion;
A second catalyst layer is formed on the surface of the gas permeable layer at a position corresponding to a space defined by an end of the laminated portion of the reinforcing film and the first catalyst layer, The electrolyte membrane and the gas permeable layer are laminated via the catalyst layer so that the catalyst layer and the second catalyst layer are in contact with each other, and the sum of the thicknesses of the first catalyst layer and the second catalyst layer is set to the first thickness. A fuel cell manufacturing method comprising a second step of forming a fuel cell with a thickness equal to or greater than the sum of the thicknesses of the catalyst layer and the reinforcing film at the laminated portion.   The method for producing a fuel cell according to claim 1 or 2, wherein the second catalyst layer is formed only on one of the anode side and the cathode side. The gas permeable layer is in any form of a gas diffusion layer, a gas flow path layer made of a metal porous body, a combination of the gas diffusion layer and the gas flow path layer,
The method for manufacturing a fuel cell according to any one of claims 1 to 3, wherein the gas permeable layers on both the anode side and the cathode side are formed of either the same form among the plurality of forms or different forms.

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