JP2008152943A - Membrane electrode assembly and manufacturing method thereof - Google Patents

Abstract

A membrane electrode assembly used in a fuel cell can be partially recycled.
A membrane electrode assembly 110 includes an anode side catalyst layer 114a and a cathode side catalyst layer 114c joined to both surfaces of an electrolyte membrane 112, respectively, and further, an anode side catalyst layer 114a and a cathode side catalyst layer 114c. An anode side gas diffusion layer 116a and a cathode side gas diffusion layer 116c are joined to the surface of the side catalyst layer 114c, respectively. The anode side 114a catalyst layer 114a and the anode side gas diffusion layer 116a include a loop member provided on the surface of the anode side catalyst layer 114a and a hook member provided on the surface of the anode side gas diffusion layer 116a. By being engaged with each other, they are detachably joined. The same applies to the joining of the cathode side catalyst layer 114c and the cathode side gas diffusion layer 116c.
[Selection] Figure 1

Description

  The present invention relates to a membrane electrode assembly used in a fuel cell, and more particularly to a membrane electrode assembly that can be partially recycled and a method for producing the same.

  A fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen has attracted attention as an energy source. This fuel cell is configured by sandwiching a membrane electrode assembly formed by joining gas diffusion electrodes (anode and cathode) on both sides of an electrolyte membrane having proton conductivity, with a separator. Each of the anode and the cathode includes a catalyst layer for promoting the electrochemical reaction. In some cases, the anode and the cathode each include a gas diffusion layer for supplying the catalyst layer while diffusing the reaction gas (fuel gas and oxidant gas) supplied from the outside of the fuel cell. .

  Conventionally, various techniques have been proposed for membrane electrode assemblies (see Patent Documents 1 to 3 below). For example, Patent Document 1 described below describes a membrane electrode assembly including a polymer electrolyte membrane in which first conductive fibers are oriented and a diffusion layer in which second conductive fibers are oriented. In this membrane electrode assembly, an electrode catalyst metal is supported on at least one of the first and second conductive fibers, and the first conductive fiber and the second conductive fiber are entangled with each other. Thus, at least one of the first conductive fiber and the second conductive fiber functions as a catalyst layer. Patent Document 2 listed below describes a fuel cell substrate having a catalyst layer including a spiral conductive member carrying a noble metal catalyst. This fuel cell substrate mainly functions as a catalyst layer when applied to a membrane electrode assembly. By the techniques described in the following Patent Documents 1 and 2, a catalyst (electrode catalyst metal, noble metal catalyst) can be effectively used for the electrochemical reaction. Patent Document 3 below describes a technique for efficiently recovering and reusing a noble metal (catalyst) and / or a fluorine-containing polymer from a membrane electrode assembly of a used polymer electrolyte fuel cell. .

JP 2005-302305 A JP-A-2005-294109 JP 2005-289001 A

  By the way, in a membrane electrode assembly in which a catalyst layer and a gas diffusion layer are joined in this order as gas diffusion electrodes on both surfaces of the electrolyte membrane, deterioration may occur only in a part of them. For example, only the electrolyte membrane or the catalyst layer may be deteriorated. In this case, for example, there may be a demand to replace only the electrolyte membrane and the catalyst layer, that is, to partially recycle the membrane electrode assembly. However, the techniques described in Patent Documents 1 to 3 do not consider partial recycling of the membrane electrode assembly.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a technique that enables partial recycling of a membrane electrode assembly used in a fuel cell.

  In order to solve at least a part of the above-described problems, the present invention employs the following configuration. The membrane / electrode assembly of the present invention is a membrane / electrode assembly used in a fuel cell, and is detachably joined to both surfaces of the electrolyte membrane and to the surface of the catalyst layer, respectively. And a gas diffusion layer. In this specification, the term “membrane electrode assembly” refers to a catalyst layer for promoting the electrochemical reaction and a reaction gas (fuel) supplied from the outside of the fuel cell on both surfaces of the electrolyte membrane, respectively. Gas diffusion layer for supplying gas and oxidant gas) to the catalyst layer while being diffused is meant to be joined in this order.

  According to the present invention, the joined body of the electrolyte membrane and the catalyst layer and the gas diffusion layer can be easily joined or separated. Therefore, when any one of the joined body of the electrolyte membrane and the catalyst layer and the gas diffusion layer deteriorates, only one of them can be replaced. That is, the membrane electrode assembly can be partially recycled.

  Specifically, for example, in the membrane electrode assembly, the catalyst layer and the gas diffusion layer are electrically conductive on one of two surfaces of the catalyst layer and the gas diffusion layer facing each other. A loop member made of a material having elasticity, and a hook member made of a material having conductivity and elasticity on the other side, and the catalyst layer and the gas diffusion layer include the loop member and the hook. You may make it join by engaging a member mutually. By doing so, the joined body of the electrolyte membrane and the catalyst layer and the gas diffusion layer can be easily joined or separated.

  In the membrane electrode assembly, the loop member and the hook member are formed such that a contact area between the loop member and the hook member is larger than a surface area of the catalyst layer or the gas diffusion layer. It is preferable to do so. By doing so, the contact resistance between the catalyst layer and the gas diffusion layer can be reduced as compared with the case where the catalyst layer and the gas diffusion layer are directly joined.

  Further, the catalyst layer and the gas diffusion layer described above each include a loop member made of a material having conductivity and elasticity on one of two surfaces of the catalyst layer and the gas diffusion layer facing each other, and the other In addition, in the membrane electrode assembly including a hook member made of a conductive and elastic material, it is preferable that the surface of the loop member and the hook member is subjected to a hydrophilic treatment. .

  In the fuel cell, water (product water) is generated in the catalyst layer on the cathode side by an electrochemical reaction between hydrogen and oxygen. This generated water also permeates through the catalyst membrane on the anode side through the electrolyte membrane. If the generated water stays in the catalyst layer excessively, flooding occurs and the power generation performance of the fuel cell is reduced. In the present invention, since the surface of the loop member and the hook member is subjected to hydrophilic treatment, drainage from the catalyst layer to the gas diffusion layer can be improved and flooding can be suppressed.

  In any of the membrane electrode assemblies described above, the gas diffusion layer has pores of the gas diffusion layer that are closer to the bonding surface with the catalyst layer in the thickness direction of the gas diffusion layer. It is preferable that the pore diameter is reduced. In other words, in the thickness direction of the gas diffusion layer, the pore diameter of the pores of the gas diffusion layer increases as the distance from the joint surface with the catalyst layer increases. It is preferable to be formed. By doing so, the drainage of the generated water in the gas diffusion layer can be improved.

The present invention can also be configured as an invention of a method for producing a membrane electrode assembly used in a fuel cell. That is, the method for producing a membrane electrode assembly of the present invention is used in a fuel cell, and a catalyst layer bonded to both surfaces of an electrolyte membrane, a gas diffusion layer bonded to the surface of the catalyst layer, and A catalyst layer forming step of forming the catalyst layer on both surfaces of the electrolyte membrane, and a gas diffusion layer forming step of forming the gas diffusion layer, respectively.
A joining step for joining the catalyst layer and the gas diffusion layer, and the catalyst layer forming step and the gas diffusion layer forming step include two surfaces of the catalyst layer and the gas diffusion layer facing each other. Including a step of forming a loop member made of a material having conductivity and elasticity on one side and a hook member made of a material having conductivity and elasticity on the other side, and the joining step includes The present invention includes a step of engaging the loop member and the hook member with each other. By doing so, the partially recyclable membrane electrode assembly of the present invention described above can be manufactured.

  In the manufacturing method, the catalyst layer forming step includes a catalyst ink applying step of applying a catalyst ink containing a catalyst on both surfaces of the electrolyte membrane, a part of the carbon microcoil on the applied catalyst ink, and a coil By embedding the surface so as to be substantially perpendicular to the surface of the electrolyte membrane, a loop member forming step of forming the loop member and a step of drying the catalyst ink may be included. By doing so, the catalyst layer including the loop member can be formed relatively easily.

  Further, in the above manufacturing method, the catalyst ink application step includes a step of forming a first catalyst layer by applying the catalyst ink on both surfaces of the electrolyte membrane and drying, and the first catalyst layer. And applying the catalyst ink again to the surface of the substrate. The loop member forming step includes a part of the carbon microcoil in the catalyst ink applied again, and a coil surface of the electrolyte membrane. It is preferable to include a step of embedding so as to be substantially perpendicular to the surface. By carrying out like this, it can prevent that a carbon microcoil contacts an electrolyte membrane directly, and can suppress damage to an electrolyte membrane.

  In any one of the manufacturing methods of a membrane electrode assembly in which the catalyst layer of the present invention includes a loop member, the gas diffusion layer forming step includes a liquid containing a carbon fiber, a binder, and a carbon microcoil. Applying the predetermined plate-like member so that the coil surface of the coil is substantially perpendicular to the surface of the gas diffusion layer, and drying the applied liquid to form the gas diffusion layer, A step of manufacturing a carbon paper in which carbon microcoils are embedded; a step of exposing a part of the carbon microcoil from the surface of the carbon paper by etching one surface of the carbon paper; and the exposure. Cutting the part of the carbon microcoil formed to form the hook member. Unishi may be. By doing so, the gas diffusion layer including the hook member can be formed relatively easily.

  Further, the gas diffusion layer forming step includes a step of applying a liquid containing carbon fiber and a binder to a predetermined plate-like member, and a part of the carbon microcoil is applied to the applied liquid on the coil surface. Embedded in the gas diffusion layer so as to be substantially perpendicular to the surface of the gas diffusion layer, and drying the liquid in which part of the carbon microcoil is embedded to form the gas diffusion layer. You may make it include the process of manufacturing the carbon paper in which one part was embedded, and the process of forming the said hook member by cut | disconnecting a part of said carbon micro coil exposed from the surface of the said carbon paper. Also by doing so, the gas diffusion layer including the hook member can be formed relatively easily.

  In the method for producing a membrane / electrode assembly of the present invention, the catalyst layer forming step includes a catalyst ink application step of applying a catalyst ink containing a catalyst on both surfaces of the electrolyte membrane, and a carbon micro coating on the applied catalyst ink. An embedding step of embedding a part of the coil so that the coil surface is substantially perpendicular to the surface of the electrolyte membrane, and the catalyst layer in which the catalyst ink is dried and a part of the carbon microcoil is embedded And forming the hook member by cutting a part of the carbon microcoil exposed from the surface of the catalyst layer. By doing so, the catalyst layer including the hook member can be formed relatively easily.

  Further, in the above manufacturing method, the catalyst ink application step includes a step of forming a first catalyst layer by applying the catalyst ink on both surfaces of the electrolyte membrane and drying, and the first catalyst layer. Applying the catalyst ink again to the surface of the substrate, wherein the embedding step includes a part of the carbon microcoil in the catalyst ink applied again, and a coil surface is the surface of the electrolyte membrane. A step of embedding so as to be substantially perpendicular to the above may be included. By carrying out like this, it can prevent that a carbon microcoil contacts an electrolyte membrane directly, and can suppress damage to an electrolyte membrane.

  In any one of the manufacturing methods of a membrane electrode assembly in which the catalyst layer of the present invention includes a hook member, the gas diffusion layer forming step includes a liquid containing a carbon fiber, a binder, and a carbon microcoil. Applying the predetermined plate-like member so that the coil surface of the coil is substantially perpendicular to the surface of the gas diffusion layer, and drying the applied liquid to form the gas diffusion layer, A step of manufacturing a carbon paper in which the carbon microcoil is embedded; and etching one surface of the carbon paper to expose a part of the carbon microcoil from the surface of the carbon paper. And a forming step. By doing so, the gas diffusion layer including the loop member can be formed relatively easily.

  In addition, the gas diffusion layer forming step includes a coating step of applying a liquid containing carbon fiber and a binder to a predetermined plate-like member, and a part of the carbon microcoil is coiled on the applied liquid. A step of embedding the surface so as to be substantially perpendicular to the surface of the gas diffusion layer, and a step of manufacturing the carbon paper on which the loop member is formed by drying the applied liquid. Also good. Also by doing so, the gas diffusion layer including the hook member can be formed relatively easily.

  The present invention can be configured as an invention of the above-described membrane electrode assembly and a method of manufacturing the membrane electrode assembly, as well as a fuel cell including the above-described membrane electrode assembly and a method of manufacturing the fuel cell. Moreover, it can also comprise as an invention of the assembly of the electrolyte membrane and catalyst layer which comprises the above-mentioned membrane electrode assembly, and its manufacturing method. Moreover, it can also be comprised as invention of the gas diffusion layer which comprises the above-mentioned membrane electrode assembly, and its manufacturing method. In addition, in each aspect, it is possible to apply the various additional elements shown above.

Hereinafter, embodiments of the present invention will be described based on examples.
A. First embodiment:
A1. Fuel cell:
FIG. 1 is an explanatory view schematically showing a schematic cross-sectional structure of a fuel cell 100 as one embodiment of the present invention. As shown in the figure, the fuel cell 100 is configured by sandwiching both surfaces of a membrane electrode assembly 110 with an anode-side separator 120 and a cathode-side separator 130. The membrane electrode assembly 110 is obtained by joining an anode and a cathode to both surfaces of an electrolyte membrane having proton conductivity. The membrane electrode assembly 110 will be described in detail later.

  As shown in the drawing, the contact surface of the anode-side separator 120 with the anode has a concavo-convex shape including a groove 122, and hydrogen as a fuel gas and an anode off-gas discharged from the anode flow through the groove 122. A gas flow path is formed.

  Further, the contact surface of the cathode-side separator 130 with the cathode also has an uneven shape including a groove 132 as shown in the figure, and the groove 132 is discharged from the cathode containing air containing oxygen as an oxidant gas. A gas flow path through which the cathode off-gas flows is formed.

  Although not shown, the anode-side separator 120 and the cathode-side separator 130 are also formed with flow paths for flowing cooling water. As materials for the anode-side separator 120 and the cathode-side separator 130, various conductive materials such as carbon and metal can be used.

A2. Membrane electrode assembly:
As shown in FIG. 1, the membrane electrode assembly 110 includes an anode side catalyst layer 114a and an anode side gas diffusion layer 116a as an anode on one surface of an electrolyte membrane 112 having proton conductivity in this order. A cathode side catalyst layer 114c and a cathode side gas diffusion layer 116c are stacked in this order as cathodes on the other surface. In this embodiment, a solid polymer electrolyte membrane is used as the electrolyte membrane 112. As the electrolyte membrane 112, another electrolyte membrane may be used. In this embodiment, carbon paper is used for the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c. As the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c, other materials having gas diffusibility and conductivity such as carbon cloth may be used.

  In the membrane / electrode assembly 110 of this example, the electrolyte membrane 112 and the anode-side catalyst layer 114a and the cathode-side catalyst layer 114c are in close contact with each other so as not to easily peel off. On the other hand, the anode side catalyst layer 114a and the anode side gas diffusion layer 116a are joined to each other so that they can be easily joined or peeled off. Further, the cathode side catalyst layer 114c and the cathode side gas diffusion layer 116c are also joined to each other so that they can be easily joined or separated. The same applies to other embodiments described later. Hereinafter, a method for manufacturing such a membrane electrode assembly 110 will be described.

A3. Manufacturing process of membrane electrode assembly:
The membrane electrode assembly 110 described above is manufactured by a manufacturing process described below. FIG. 2 is an explanatory diagram showing the overall flow of the manufacturing process of the membrane electrode assembly 110.

  First, the anode side catalyst layer 114a and the cathode side catalyst layer 114c are formed on both surfaces of the electrolyte membrane 112, respectively (step S100). Next, the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c are manufactured (step S110). These steps will be described in detail later. Then, the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c are joined to the surfaces of the anode side catalyst layer 114a and the cathode side catalyst layer 114c, respectively (step S120). The membrane electrode assembly 110 is manufactured by the above manufacturing process.

  FIG. 3 is an explanatory diagram illustrating details of step S100 (see FIG. 2) of the manufacturing process of the membrane electrode assembly 110 in the first embodiment.

  First, as shown in FIG. 3A, the anode catalyst ink is applied to one surface of the electrolyte membrane 112 and dried to form the first anode catalyst layer 114a1. The catalyst ink for anode includes, for example, carbon carrying a catalytic metal that promotes an electrochemical reaction between hydrogen and oxygen such as platinum (Pt), a Nafion dispersion solution (Nafion is a registered trademark) as an electrolyte solution, a solvent ( For example, water, ethanol, polyethylene glycol) are mixed. These mixing ratios can be arbitrarily set.

  Next, as shown in FIG. 3B, the anode catalyst ink is again applied to the surface of the first anode catalyst layer 114a1 to form the second anode catalyst layer 114a2 in an undried state. To do.

  Next, as shown in FIG. 3C, a part of the carbon microcoil 115 is placed on the second anode catalyst layer 114 a 2 in an undried state, and the coil surface is approximately the surface of the electrolyte membrane 112. The second anode catalyst layer 114a2 in an undried state is embedded in a substantially uniform manner so as to be vertical. The carbon microcoil is a member having conductivity and elasticity, and is manufactured by a well-known technique (for example, vapor phase growth using acetylene as a raw material). In this embodiment, the carbon microcoil 115 having a coil diameter of about several microns is used. The carbon microcoil 115 is subjected to a hydrophilic treatment.

  Then, as shown in FIG. 3D, the anode side catalyst layer 114a including the loop member 115al is formed on the electrolyte membrane 112 by drying the second anode side catalyst layer 114a2.

  Although illustration and description are omitted, the cathode side catalyst layer 114c including the loop member is formed on the cathode side in the same manner as the anode side catalyst layer 114a described above.

  FIG. 4 is an explanatory diagram for explaining details of step S110 (see FIG. 2) of the manufacturing process of the membrane electrode assembly 110 in the first embodiment. Although only the manufacturing process of the anode side gas diffusion layer 116a will be described here, the manufacturing process of the cathode side gas diffusion layer 116c is the same as the manufacturing process of the anode side gas diffusion layer 116a.

  First, a paste including a carbon fiber as a carbon paper raw material, a binder for bonding the carbon fiber, and a carbon microcoil 117 is prepared. The coil diameter of the carbon microcoil 117 is substantially the same as the coil diameter of the carbon microcoil 115 described above. In addition, the carbon microcoil 117 is subjected to a hydrophilic treatment in the same manner as the carbon microcoil 115. Then, as shown in FIG. 4A, this paste is applied to a plate-like member 200 and dried to produce a carbon paper 116ap in which the entire carbon microcoil 117 is embedded. At this time, the carbon microcoil 117 is disposed such that the coil surface is substantially perpendicular to the surface of the carbon paper 116ap. Further, the carbon microcoils 117 are arranged substantially uniformly on the entire surface of the carbon paper 116ap.

  Next, as shown in FIG. 4B, by etching one surface of the carbon paper 116ap, a part of the carbon microcoil 117 is looped from the surface of the carbon paper (anode side gas diffusion layer 116a). Expose to the shape.

  Next, a part of the carbon microcoil 117 exposed in a loop shape from the surface of the carbon paper is cut with a cutter to produce a hook member 117ah.

  And as shown in FIG.4 (d), by peeling these from the plate-shaped member 200, the anode side gas diffusion layer 116a provided with the hook member 117ah on one surface can be manufactured.

  In step S120 described above with reference to FIG. 2, although not shown, a loop member 115al provided in the anode side catalyst layer 114a and a hook member 117ah provided in the anode side gas diffusion layer 116a are provided. By engaging each other, and by engaging each other with a loop member provided in the cathode side catalyst layer 114c and a hook member provided in the cathode side gas diffusion layer 116c, the anode side catalyst layer 114a, and The anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c are joined to the cathode side catalyst layer 114c, respectively.

  The membrane electrode assembly 110 of the first embodiment can be manufactured by the above manufacturing process. Further, the fuel cell 100 shown in FIG. 1 can be manufactured by sandwiching the membrane electrode assembly 110 between the anode side separator 120 and the cathode side separator 130.

  According to the membrane electrode assembly 110 of the first embodiment described above, the anode-side catalyst layer 114a and the cathode-side gas diffusion layer 116c include the elastic loop member 115al and the elastic hook member 117ah. Since it joins by making it engage, the anode side catalyst layer 114a and the anode side gas diffusion layer 116a can be easily joined or peeled off. The same applies to the joining of the cathode side catalyst layer 114c and the cathode side catalyst layer 114c. Therefore, any one of the assembly of the electrolyte membrane 112 and the catalyst layer (the anode side catalyst layer 114a and the cathode side catalyst layer 114c), the anode side gas diffusion layer 116a, and the cathode side gas diffusion layer 116c is provided. When it deteriorates, only one of them can be replaced. That is, the membrane electrode assembly 110 can be partially recycled.

  Further, in the membrane electrode assembly 110 of the present embodiment, since the loop member and the hook member are subjected to hydrophilic treatment as described above, the membrane electrode assembly 110 is attached to the fuel cell 100. When the power generation is performed, the generated water generated by the electrochemical reaction between hydrogen and oxygen is supplied from the anode side catalyst layer 114a and the cathode side catalyst layer 114c to the anode side gas diffusion layer 116a, respectively. In addition, the cathode side gas diffusion layer 116c can be quickly discharged to suppress flooding.

  Further, in the membrane electrode assembly 110 of this example, the catalyst layer and the gas diffusion layer are joined by bringing a conductive loop member and a conductive hook member into contact in a three-dimensional manner. Yes. Therefore, the contact area can be made larger than when the catalyst layer and the gas diffusion layer are directly joined. As a result, the contact resistance between the catalyst layer and the gas diffusion layer can be reduced.

  In the membrane / electrode assembly 110 of this example, as described with reference to FIG. 3, after the first anode catalyst layer 114a1 is formed on the surface of the electrolyte membrane 112, the first anode catalyst layer is formed. Since the second anode catalyst layer 114a2 is formed on 114a1 and the carbon microcoil 115 is embedded, the carbon microcoil 115 is prevented from directly contacting the electrolyte membrane 112, and damage to the electrolyte membrane 112 is suppressed. be able to. The same applies to the cathode side.

B. Second embodiment:
In the membrane electrode assembly 110 of the first embodiment, the catalyst layer includes a loop member and the gas diffusion layer includes a hook member. However, in the membrane electrode assembly 110 of the second embodiment, the catalyst layer includes a hook member. The gas diffusion layer is provided with a loop member. The configuration of the fuel cell 100 of the second embodiment and the overall flow of the manufacturing process of the membrane electrode assembly 110 are the same as those of the first embodiment (see FIGS. 1 and 2). Hereinafter, the detail of the manufacturing process of the membrane electrode assembly 110 of 2nd Example is demonstrated.

  FIG. 5 is an explanatory diagram illustrating details of step S100 (see FIG. 2) of the manufacturing process of the membrane electrode assembly 110 in the second embodiment.

  First, as shown in FIG. 5A, the anode catalyst ink is applied to one surface of the electrolyte membrane 112 and dried to form the first anode catalyst layer 114a1.

  Next, as shown in FIG. 5B, the anode catalyst ink is again applied to the surface of the first anode catalyst layer 114a1 to form the second anode catalyst layer 114a2 in an undried state. To do.

  Next, as shown in FIG. 5C, a part of the carbon microcoil 115 is placed on the second anode catalyst layer 114 a 2 in an undried state, and the coil surface is substantially the surface of the electrolyte membrane 112. The second anode catalyst layer 114a2 in an undried state is embedded in a substantially uniform manner so as to be vertical.

  Next, as shown in FIG. 5D, by drying the second anode side catalyst layer 114a2, a part of the carbon microcoil 115 was exposed in a loop form from the surface of the anode side catalyst layer 114a. An anode side catalyst layer 114 a is formed on the electrolyte membrane 112.

  Then, as shown in FIG. 5E, a part of the carbon microcoil 115 exposed in a loop shape from the surface of the anode side catalyst layer 114a is cut with a cutter to produce a hook member 115ah.

  Although illustration and description are omitted, the cathode side catalyst layer 114c including the hook member is formed on the cathode side in the same manner as the anode side catalyst layer 114a described above.

  FIG. 6 is an explanatory diagram illustrating details of step S110 (see FIG. 2) of the manufacturing process of the membrane electrode assembly 110 in the second embodiment. Although only the manufacturing process of the anode side gas diffusion layer 116a will be described here, the manufacturing process of the cathode side gas diffusion layer 116c is the same as the manufacturing process of the anode side gas diffusion layer 116a.

  First, a paste containing a carbon fiber as a raw material for carbon paper and a binder for bonding the carbon fiber is prepared. And this paste is apply | coated to the plate-shaped member 200 as shown to Fig.4 (a), and undried carbon paper 116ap is produced.

  Next, as shown in FIG. 6B, a part of the carbon microcoil 117 is placed on the undried carbon paper 116ap, and the coil surface is substantially perpendicular to the surface of the undried carbon paper 116ap. As described above, the second anode catalyst layer 114a2 in an undried state is embedded and disposed almost uniformly.

  Then, by drying the carbon paper 116ap in which a part of the carbon microcoil 117 is embedded, a carbon paper (anode side gas diffusion layer 116a) in which a part of the carbon microcoil 117 is exposed in a loop shape is produced.

  And as shown in FIG.6 (d), by peeling these from the plate-shaped member 200, the anode side gas diffusion layer 116a provided with the loop member 117al on one surface can be manufactured.

  In step S120 described above with reference to FIG. 2, although not shown, the hook member 115ah provided in the anode side catalyst layer 114a and the loop member 117al provided in the anode side gas diffusion layer 116a are provided. By engaging each other, and by engaging each other with a hook member provided in the cathode side catalyst layer 114c and a loop member provided in the cathode side gas diffusion layer 116c, the anode side catalyst layer 114a, and The anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c are joined to the cathode side catalyst layer 114c, respectively.

  Through the above manufacturing process, the membrane electrode assembly 110 of the second embodiment can be manufactured. Further, the fuel cell 100 shown in FIG. 1 can be manufactured by sandwiching the membrane electrode assembly 110 between the anode side separator 120 and the cathode side separator 130.

  According to the membrane electrode assembly 110 of the second embodiment described above, the anode-side catalyst layer 114a and the cathode-side gas diffusion layer 116c are formed by connecting the elastic hook member 115ah and the elastic loop member 117al to each other. Since it joins by making it engage, the anode side catalyst layer 114a and the anode side gas diffusion layer 116a can be easily joined or peeled off. The same applies to the joining of the cathode side catalyst layer 114c and the cathode side catalyst layer 114c. Therefore, any one of the assembly of the electrolyte membrane 112 and the catalyst layer (the anode side catalyst layer 114a and the cathode side catalyst layer 114c), the anode side gas diffusion layer 116a, and the cathode side gas diffusion layer 116c is provided. When it deteriorates, only one of them can be replaced. That is, the membrane electrode assembly 110 can be partially recycled.

C. Variation:
As mentioned above, although several embodiment of this invention was described, this invention is not limited to such embodiment at all, and implementation in various aspects is possible within the range which does not deviate from the summary. It is. For example, the following modifications are possible.

C1. Modification 1:
In the second embodiment, carbon paper is used as the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c. However, the present invention is not limited to this. For example, carbon cloth may be used instead of carbon paper.

  FIG. 7 is an explanatory view showing a modified anode side gas diffusion layer 116Aa and cathode side gas diffusion layer 116Ac. In the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c of this modification, carbon cloth is used instead of carbon paper. As shown in the figure, for example, a conductive material such as carbon fiber is used for the carbon cloth. It is produced by sewing fibers having elasticity and elasticity so that a loop member 118 is formed on one surface. The carbon cloth itself may be woven so that the loop member 118 is formed. This also produces the anode side gas diffusion layer 116Aa and the cathode side gas diffusion layer 116Ac having the same functions as the anode side gas diffusion layer 116a and the cathode side gas diffusion layer 116c in the second embodiment. be able to.

C2. Modification 2:
In the above embodiment, the carbon microcoils 115 and 117 are subjected to the hydrophilic treatment, but the present invention is not limited to this, and the carbon microcoils 115 and 117 may not be subjected to the hydrophilic treatment. However, by performing hydrophilic treatment on the carbon microcoils 115 and 117, the drainage efficiency of generated water from the catalyst layer to the gas diffusion layer can be improved as described above.

C3. Modification 3:
In the above embodiment, when the anode side catalyst layer 114a is formed on the electrolyte membrane 112 in the manufacturing process of the membrane electrode assembly 110, the second anode side catalyst is formed after the first anode side catalyst layer 114a1 is formed. Although the layer 114a2 is formed, the present invention is not limited to this. The anode side catalyst layer 114a may be formed as a single layer. The same applies to the cathode side catalyst layer 114c.

C4. Modification 4:
In the above embodiment, in the manufacturing process of the membrane electrode assembly 110, the carbon paper has a single-layer structure when the anode gas diffusion layer 116a is manufactured. However, the present invention is not limited to this. For example, the carbon paper has a multi-layer structure, and in the thickness direction of the carbon paper, the larger the distance from the bonding surface with the anode-side catalyst layer 114a, the larger the pore diameter or porosity of the carbon paper has. You may make it form so that it may become. By doing so, the drainage of the generated water in the anode side gas diffusion layer 116a can be improved. The same applies to the cathode-side gas diffusion layer 116c.

C5. Modification 5:
In the first embodiment, in the manufacturing process of the membrane electrode assembly 110, as shown in FIG. 4, the carbon paper 116ap in which the entire carbon microcoil 117 is embedded is manufactured when the anode-side gas diffusion layer 116a is manufactured. By etching this surface, a part of the carbon microcoil 117 is exposed in a loop shape from the surface of the carbon paper. However, the present invention is not limited to this. For example, the hook member 117ah may be manufactured by manufacturing the anode-side gas diffusion layer 116a and cutting a part of the loop member 117al in the same manner as the second embodiment shown in FIG.

  In the second embodiment, in the manufacturing process of the membrane electrode assembly 110, as shown in FIG. 6, a part of the carbon microcoil 117 is embedded in the undried carbon paper 116ap, and the carbon microcoil 117 is formed. Although the anode side gas diffusion layer 116a partially exposed in a loop shape is manufactured, the present invention is not limited to this. For example, similarly to the first embodiment shown in FIG. 4, a carbon paper 116ap in which the entire carbon microcoil 117 is embedded is manufactured, and this surface is etched, so that one of the carbon microcoils 117 is removed from the surface of the carbon paper. The loop member 117al may be manufactured by exposing the portion in a loop shape.

C6. Modification 6:
In the above embodiment, the carbon microcoils 115 and 117 are used to form the loop member and the hook member, but the present invention is not limited to this. Other members having conductivity and elasticity may be used.

It is explanatory drawing which shows typically the general | schematic cross-section of the fuel cell 100 as one Example of this invention. It is explanatory drawing which shows the flow of the whole manufacturing process of the membrane electrode assembly 110. FIG. It is explanatory drawing explaining the detail of step S100 of the manufacturing process of the membrane electrode assembly 110 in 1st Example. It is explanatory drawing explaining the detail of step S110 of the manufacturing process of the membrane electrode assembly 110 in 1st Example. It is explanatory drawing explaining the detail of step S100 of the manufacturing process of the membrane electrode assembly 110 in 2nd Example. It is explanatory drawing explaining the detail of step S110 of the manufacturing process of the membrane electrode assembly 110 in 2nd Example. It is explanatory drawing which shows anode side gas diffusion layer 116Aa and cathode side gas diffusion layer 116Ac as a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Fuel cell 110 ... Membrane electrode assembly 112 ... Electrolyte membrane 114a ... Anode side catalyst layer 114a1 ... 1st anode side catalyst layer 114a2 ... 2nd anode side catalyst layer 114c ... Cathode side catalyst layer 115 ... Carbon microcoil 115ah ... hook member 115al ... loop member 116a, 116Aa ... anode side gas diffusion layer 116c, 116Ac ... cathode side gas diffusion layer 116ap ... carbon paper 117 ... carbon microcoil 117ah ... hook member 117al ... loop member 118 ... loop member 120 ... anode side Separator 122 ... Groove part 130 ... Cathode side separator 132 ... Groove part 200 ... Plate-shaped member

Claims (14)

A membrane electrode assembly used in a fuel cell,
A catalyst layer bonded to both surfaces of the electrolyte membrane,
A gas diffusion layer detachably joined to the surface of the catalyst layer, and
A membrane electrode assembly comprising: The membrane electrode assembly according to claim 1,
The catalyst layer and the gas diffusion layer include a loop member made of a material having conductivity and elasticity on one of two surfaces of the catalyst layer and the gas diffusion layer facing each other. A hook member made of a material having conductivity and elasticity,
The catalyst layer and the gas diffusion layer are joined by engaging the loop member and the hook member with each other,
Membrane electrode convenience. The membrane electrode assembly according to claim 2, wherein
The loop member and the hook member are formed so that a contact area between the loop member and the hook member is larger than a surface area of the catalyst layer or the gas diffusion layer.
Membrane electrode assembly. The membrane electrode assembly according to claim 2 or 3, wherein
The loop member and the surface of the hook member are subjected to hydrophilic treatment,
Membrane electrode assembly. A membrane electrode assembly according to any one of claims 1 to 4,
The gas diffusion layer is formed so that the pore diameter of the pores of the gas diffusion layer becomes smaller as the distance from the joint surface with the catalyst layer is shorter in the thickness direction of the gas diffusion layer. ,
Membrane electrode assembly. A method for producing a membrane electrode assembly used in a fuel cell, comprising a catalyst layer bonded to both surfaces of an electrolyte membrane, and a gas diffusion layer bonded to the surface of the catalyst layer, respectively.
A catalyst layer forming step of forming the catalyst layer on both surfaces of the electrolyte membrane,
A gas diffusion layer forming step of forming the gas diffusion layer;
A bonding step of bonding the catalyst layer and the gas diffusion layer,
The catalyst layer forming step and the gas diffusion layer forming step include a loop member made of a material having conductivity and elasticity on one of two surfaces of the catalyst layer and the gas diffusion layer facing each other. And forming a hook member made of a material having conductivity and elasticity on the other side,
The joining step includes a step of engaging the loop member and the hook member with each other,
Production method. The manufacturing method according to claim 6,
The catalyst layer forming step includes
A catalyst ink coating step of coating a catalyst ink containing a catalyst on both surfaces of the electrolyte membrane;
A loop member forming step of forming the loop member by embedding a part of the carbon microcoil in the applied catalyst ink so that the coil surface is substantially perpendicular to the surface of the electrolyte membrane;
Drying the catalyst ink;
Manufacturing method. The manufacturing method according to claim 7,
The catalyst ink application step includes
Forming a first catalyst layer by applying and drying the catalyst ink on both surfaces of the electrolyte membrane; and
Applying the catalyst ink to the surface of the first catalyst layer again.
The loop member forming step includes
Embedding a part of the carbon microcoil in the reapplied catalyst ink so that the coil surface is substantially perpendicular to the surface of the electrolyte membrane;
Production method. The manufacturing method according to claim 7 or 8,
The gas diffusion layer forming step includes
Applying a liquid containing carbon fiber, a binder, and a carbon microcoil to a predetermined plate member such that the coil surface of the carbon microcoil is substantially perpendicular to the surface of the gas diffusion layer;
Drying the applied liquid to form the gas diffusion layer, producing a carbon paper in which the carbon microcoil is embedded;
Exposing a portion of the carbon microcoil from the surface of the carbon paper by etching one surface of the carbon paper;
Forming the hook member by cutting a portion of the exposed carbon microcoil;
Manufacturing method. The manufacturing method according to claim 7 or 8,
The gas diffusion layer forming step includes
Applying a liquid containing carbon fiber and a binder to a predetermined plate member;
Embedding part of the carbon microcoil in the applied liquid so that the coil surface is substantially perpendicular to the surface of the gas diffusion layer;
Drying the liquid in which part of the carbon microcoil is embedded to form the gas diffusion layer, and manufacturing the carbon paper in which part of the carbon microcoil is embedded;
Forming the hook member by cutting a part of the carbon microcoil exposed from the surface of the carbon paper;
Manufacturing method. The manufacturing method according to claim 6,
The catalyst layer forming step includes
A catalyst ink coating step of coating a catalyst ink containing a catalyst on both surfaces of the electrolyte membrane;
An embedding step of embedding a part of the carbon microcoil in the applied catalyst ink so that the coil surface is substantially perpendicular to the surface of the electrolyte membrane;
Drying the catalyst ink to form the catalyst layer in which part of the carbon microcoil is embedded;
Forming the hook member by cutting a portion of the carbon microcoil exposed from the surface of the catalyst layer;
Manufacturing method. The manufacturing method according to claim 11,
The catalyst ink application step includes
Forming a first catalyst layer by applying and drying the catalyst ink on both surfaces of the electrolyte membrane; and
Applying the catalyst ink to the surface of the first catalyst layer again.
The embedding step includes
Embedding a part of the carbon microcoil in the reapplied catalyst ink so that the coil surface is substantially perpendicular to the surface of the electrolyte membrane;
Production method. The manufacturing method according to claim 11 or 12,
The gas diffusion layer forming step includes
Applying a liquid containing carbon fiber, a binder, and a carbon microcoil to a predetermined plate member such that the coil surface of the carbon microcoil is substantially perpendicular to the surface of the gas diffusion layer;
Drying the applied liquid to form the gas diffusion layer, producing a carbon paper in which the carbon microcoil is embedded;
Etching one surface of the carbon paper to expose a part of the carbon microcoil from the surface of the carbon paper and forming the loop member;
Manufacturing method. The manufacturing method according to claim 11 or 12,
The gas diffusion layer forming step includes
An application step of applying a liquid containing carbon fiber and a binder to a predetermined plate member;
Embedding part of the carbon microcoil in the applied liquid so that the coil surface is substantially perpendicular to the surface of the gas diffusion layer;
A step of producing a carbon paper on which the loop member is formed by drying the applied liquid; and
Manufacturing method.

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