JP2008010164A - Gas diffusion layer used for fuel cell, and the fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To move water generated in an electrochemical reaction of hydrogen and oxygen, from a catalyst layer to a desired position on the surface of a gas diffusion layer in a fuel cell. <P>SOLUTION: In the gas diffusion layer used in the fuel cell (for example, gas diffusion layer 140 on the anode side), a hydrophilic fiber (148) is sewn on a desired position so that a part of the hydrophilic fiber may be exposed on both sides of a diffusion layer base material (142) having water repellency. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a gas diffusion layer used in a fuel cell and a fuel cell.

  Conventionally, a fuel cell that generates electricity by an electrochemical reaction between hydrogen and oxygen has attracted attention as an energy source. This fuel cell has a membrane electrode assembly in which an anode (hydrogen electrode) and a cathode (oxygen electrode) are bonded to both surfaces of a predetermined electrolyte membrane, respectively. Hydrogen and oxygen are supplied respectively. Each of the anode and the cathode includes a catalyst layer for promoting the electrochemical reaction and a gas diffusion layer for supplying the reaction gas while diffusing the catalyst layer. In the layer, water (product water) is generated by the cathode reaction during power generation. This generated water passes through the gas diffusion layer from the catalyst layer on the cathode side, and is discharged together with the cathode off-gas discharged outside the fuel cell without being consumed by the cathode reaction. In addition, the produced water may permeate the electrolyte membrane from the cathode side and ooze out to the anode side. In this case, the produced water oozed out to the anode side permeates the gas diffusion layer from the catalyst layer on the anode side, It is discharged together with the anode off-gas discharged outside the fuel cell without being consumed in the anode reaction.

  When the generated water is excessively retained in the vicinity of the electrolyte membrane of the fuel cell, so-called flooding occurs, and the diffusion and supply of the reaction gas are hindered by the generated water, thereby reducing the power generation performance of the fuel cell. Therefore, conventionally, in order to suppress flooding, a gas diffusion layer having water repellency has been formed by dispersing polytetrafluoroethylene or carbon black between carbon cloth or carbon fibers of carbon paper. It has been broken. However, in this gas diffusion layer, the reaction gas passage can be secured by repelling the generated water, but the excess generated water can be quickly moved from the catalyst layer to the surface of the gas diffusion layer. There wasn't.

  In recent years, a technique has been proposed in which a reaction gas passage in the gas diffusion layer is secured and excess generated water is quickly moved from the catalyst layer to the surface of the gas diffusion layer. For example, Patent Document 1 below describes a technique in which a woven fabric in which hydrophilic carbon fibers and water-repellent carbon fibers are woven is used as a gas diffusion layer. In this technology, water is repelled by water-repellent carbon fibers to ensure a reaction gas passage in the gas diffusion layer, and the generated water is quickly moved along the hydrophilic carbon fibers to the surface of the gas diffusion layer. Can do.

JP 2002-15747 A

  By the way, in the fuel cell, the membrane electrode assembly is generally sandwiched between the separators. Therefore, for example, due to the shape of the separator, the surface of the gas diffusion layer has a region suitable for discharging generated water. Inappropriate areas may occur. In this case, it is desirable that the generated water is moved to a region suitable for discharging the generated water on the surface of the gas diffusion layer and not moved to a region not suitable for discharging the generated water. However, the technique described in Patent Document 1 cannot realize the above request because the hydrophilic carbon fibers cannot be accurately arranged at a desired position on the surface of the gas diffusion layer.

  The present invention has been made in order to solve the above-described problems. In a fuel cell, the generated water generated by the electrochemical reaction between hydrogen and oxygen is transferred from the catalyst layer to the desired surface of the gas diffusion layer. The purpose is to move to a position.

In order to solve at least a part of the above-described problems, the present invention employs the following configuration.
The gas diffusion layer of the present invention comprises:
A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And the gas diffusion layer used in a fuel cell comprising a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
A diffusion layer substrate having water repellency;
A hydrophilic fiber having hydrophilicity,
The gist of the hydrophilic fiber is that it is sewn to the diffusion layer base material such that a part of the hydrophilic fiber is exposed on both surfaces of the diffusion layer base material.

  In addition, as a hydrophilic fiber, carbon fiber, an aramid fiber, etc. can be used, for example.

  In the present invention, since hydrophilic fibers are sewn to the diffusion layer base material, the hydrophilic fibers can be accurately arranged at desired positions on the surface of the gas diffusion layer. And since a part of hydrophilic fiber is exposed on both surfaces of a diffusion layer base material, water is rapidly moved along the hydrophilic fiber from one surface of the gas diffusion layer to the other surface. Can do. Therefore, in the fuel cell using this gas diffusion layer, the generated water generated by the electrochemical reaction between hydrogen and oxygen is moved from the catalyst layer to a region suitable for discharging the generated water on the surface of the gas diffusion layer. In addition, it can be prevented from moving to a region that is not suitable for discharging generated water. That is, according to the present invention, in the fuel cell, the generated water generated by the electrochemical reaction between hydrogen and oxygen can be moved from the catalyst layer to a desired position on the surface of the gas diffusion layer.

In the gas diffusion layer,
The diffusion layer base material includes a low water-repellent layer having relatively low water repellency and a high water-repellent layer having relatively high water repellency,
The high water-repellent layer may be provided on a surface in contact with the catalyst layer.

  By doing so, in the fuel cell using this gas diffusion layer, the gas diffusion property of the gas diffusion layer at the interface with the catalyst layer can be further improved, and the gas supply efficiency can be improved. As a result, the power generation efficiency of the fuel cell can be improved.

In any of the gas diffusion layers described above,
It is preferable that the hydrophilic fibers are sewn so as to penetrate in a direction perpendicular to the surface of the diffusion layer base material.

  By doing so, the generated water can be moved from one surface of the gas diffusion layer to the other surface at the shortest distance.

The present invention can also be configured as a fuel cell invention. That is,
The first fuel cell of the present invention comprises:
A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
The membrane electrode assembly includes any of the gas diffusion layers of the present invention described above as the gas diffusion layer,
The fuel cell includes a separator that sandwiches both surfaces of the membrane electrode assembly,
The separator is
A rib portion in contact with the gas diffusion layer;
A groove portion serving as a gas flow path through which the gas flows,
At least the surface of the rib part has hydrophilicity,
The gist of the gas diffusion layer is that the hydrophilic fiber is sewn to the diffusion layer substrate so that a part of the hydrophilic fiber contacts the rib portion.

  By doing so, the generated water that has moved from the catalyst layer along the hydrophilic fiber of the gas diffusion layer can be spread quickly on the surface of the rib portion of the separator and discharged to the outside by the flow of gas flowing in the gas flow path. it can. As a result, flooding in the fuel cell can be suppressed.

In the fuel cell,
The rib portion may be made of a porous member.

  By carrying out like this, the produced | generated water which moved along the hydrophilic fiber of a gas diffusion layer from a catalyst layer can be spread also inside the rib part of a separator.

The second fuel cell of the present invention is
A catalyst layer for providing a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
The membrane electrode assembly includes any of the gas diffusion layers of the present invention described above as the gas diffusion layer,
The fuel cell includes a separator that sandwiches both surfaces of the membrane electrode assembly,
The separator is
A rib portion in contact with the gas diffusion layer;
A groove portion serving as a gas flow path through which the gas flows,
The gas flow path is a gas flow path through which the dried gas flows,
The gist of the gas diffusion layer is that the hydrophilic fiber is sewn to the diffusion layer substrate so that a part of the hydrophilic fiber is exposed to the gas flow path.

  By doing so, the generated water that has moved from the catalyst layer along the hydrophilic fiber of the gas diffusion layer can be dried by the dry gas and discharged to the outside by the gas flow flowing in the gas flow path. As a result, flooding in the fuel cell can be suppressed.

  Further, in the second fuel cell of the present invention, unlike the above-described first fuel cell of the present invention, since the surface of the separator does not have hydrophilicity, in the gas diffusion layer, a part of the hydrophilic fiber is present. When hydrophilic fibers are sewn to the diffusion layer base so as to come into contact with the rib portion of the separator, the generated water that has moved along the hydrophilic fibers of the gas diffusion layer is less likely to spread on the surface of the rib portion. For this reason, there is a possibility that the generated water stays at the contact portion between the rib portion and the gas diffusion layer and is difficult to be discharged. In the present invention, in the gas diffusion layer, the hydrophilic fiber is sewn to the diffusion layer base material so that a part of the hydrophilic fiber does not contact the rib portion of the separator. It is possible to avoid a problem that the generated water stays in the contact portion and is difficult to be discharged.

Moreover, this invention can also be comprised as invention of the manufacturing method of the gas diffusion layer demonstrated previously. That is,
The production method of the present invention comprises:
A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And a gas diffusion layer for use in a fuel cell comprising a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
Preparing a diffusion layer substrate having water repellency;
Preparing a hydrophilic fiber having hydrophilicity;
Sewing the hydrophilic fibers to the diffusion layer substrate so that a part of the hydrophilic fibers are exposed on both surfaces of the gas diffusing substrate;
It is a summary to provide.

  By carrying out like this, the gas diffusion layer of this invention demonstrated previously can be manufactured.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. Fuel cell stack configuration:
B. Single cell:
C. Gas diffusion layer:
C1. Anode side gas diffusion layer:
C2. Cathode side gas diffusion layer:
C3. Method for producing gas diffusion layer Variation:

A. Fuel cell stack configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of a fuel cell stack 10 as an embodiment of the present invention. As shown in the figure, the fuel cell stack 10 is formed by laminating a predetermined number of unit cells 100 that generate power by an electrochemical reaction between hydrogen and oxygen. The number of stacked single cells 100 can be arbitrarily set according to the output required for the fuel cell stack 10. Details of the single cell 100 will be described later.

  The fuel cell stack 10 is configured by laminating an end plate 12, an insulating plate 16, a current collecting plate 18, a plurality of single cells 100, a current collecting plate 20, an insulating plate 22, and an end plate 14 in this order from one end. The end plates 12 and 14 are made of metal such as steel in order to ensure rigidity. The current collecting plates 18 and 20 are formed of a gas impermeable conductive member such as dense carbon or a copper plate. The insulating plates 16 and 22 are formed of an insulating member such as rubber or resin. The current collector plates 18 and 20 are provided with output terminals 19 and 21, respectively, so that the power generated by the fuel cell stack 10 can be output.

  One end plate 14 has a fuel gas supply port 35, a fuel gas discharge port 36, an oxidant gas supply port 33, an oxidant gas discharge port 34, a cooling water supply port 31, and a cooling water discharge port 32. Is provided. The fuel gas supplied from the fuel gas supply port 35 to the fuel cell stack 10 is distributed to each single cell 100 while flowing toward the end plate 12. The fuel gas distributed to each single cell 100 flows through the flow path in the single cell 100 from the upper side to the lower side in the drawing, then flows to the end plate 14 side, and is discharged from the fuel gas discharge port 36. Similarly, after the oxidant gas is supplied from the oxidant gas supply port 33, it is distributed to each single cell 100 while flowing toward the end plate 12, and after flowing through the flow path in each single cell 100, It is discharged from the gas discharge port 34. In the fuel cell stack 10, a gas flow path of each single cell 100 is formed inside so as to realize such a gas flow.

  From the oxidant gas discharge port 34 and the fuel gas discharge port 36, the generated water generated by the electrochemical reaction between hydrogen and oxygen in each unit cell 100 during power generation is discharged together with the exhaust gas.

  Although not shown in the figure, the fuel cell stack 10 is used to suppress a decrease in cell performance due to an increase in contact resistance or the like in any part of the stack structure, or to suppress gas leakage. A pressing force is applied in the stacking direction of the stack structure.

B. Single cell:
FIG. 2 is an explanatory diagram schematically showing a cross-sectional structure of the single cell 100. This single cell 100 is configured by sandwiching both surfaces of a membrane electrode assembly 110 with separators 170 and 180.

  The membrane electrode assembly 110 includes an anode-side catalyst layer 130 and an anode-side gas diffusion layer 140 stacked in this order as an anode (hydrogen electrode) on one surface of an electrolyte membrane 120 having proton conductivity, On this surface, a cathode side catalyst layer 150 and a cathode side gas diffusion layer 160 are laminated in this order as a cathode (oxygen electrode). In this embodiment, a solid polymer electrolyte membrane is used as the electrolyte membrane 120. Other electrolyte membranes may be used as the electrolyte membrane 120.

  Note that air containing hydrogen as a fuel gas and oxygen as an oxidant gas is supplied to the anode and the cathode of the membrane electrode assembly 110, respectively, and electric power is generated by an electrochemical reaction between hydrogen and oxygen. Done. At this time, the cathode-side catalyst layer 150 also generates water by the cathode reaction. The generated water generated in the cathode side catalyst layer 150 permeates the electrolyte membrane 120 and oozes out to the anode side catalyst layer 130. Then, if these generated waters are excessively retained in the membrane electrode assembly 110, flooding occurs, and thus the generated water is quickly discharged to the outside by a method described later.

  As shown in the drawing, the separator 170 disposed on the anode side of the membrane electrode assembly 110 has an uneven shape including a rib portion 172 and a groove portion 174, and the groove portion 174 provides a gas flow path through which hydrogen flows. Form. In the present embodiment, the rib portion 172 is formed of a porous body. Further, the surface of the rib portion 172 is subjected to a hydrophilic treatment.

  As illustrated, the separator 180 disposed on the cathode side of the membrane electrode assembly 110 also has an uneven shape including a rib portion 182 and a groove portion 184, and the groove portion 184 has a gas flow path through which air flows. Form. In this embodiment, it is assumed that dry air flows through the groove 184 of the separator 180. In addition, unlike the separator 170 arrange | positioned at the anode side of the membrane electrode assembly 110, the rib part 182 in the separator 180 is not a porous body, and the hydrophilic process is not given to the surface.

  As materials for the separators 170 and 180, various materials having conductivity such as carbon and metal can be used.

C. Gas diffusion layer:
Hereinafter, the gas diffusion layer which is a characteristic component in the present invention will be described.

C1. Anode side gas diffusion layer:
FIG. 3 is an explanatory view schematically showing a cross-sectional structure of the anode-side gas diffusion layer 140 of the membrane electrode assembly 110. Further, in this figure, the arrangement relationship between the anode-side gas diffusion layer 140 and the separator 170 when the membrane electrode assembly 110 and the separator 170 are brought into contact with each other, and the electrolyte membrane 120 in the membrane electrode assembly 110. The arrangement relationship is also shown.

  As shown in the figure, the anode-side gas diffusion layer 140 is hydrophilic to a diffusion layer substrate 142 including a low water repellency diffusion layer 144 having a relatively low water repellency and a high water repellency diffusion layer 146 having a relatively high water repellency. The hydrophilic fiber 148 having the property is sewn so that a part thereof is exposed on both surfaces of the diffusion layer base material 142. The hydrophilic fibers 148 are sewn so as to penetrate in a direction perpendicular to the surface of the diffusion layer base material 142. The diffusion layer base material 142 is formed, for example, by applying a water repellent to one surface of a carbon cloth in which polytetrafluoroethylene or carbon black is dispersed between carbon fibers. As the hydrophilic fiber 148, for example, an aramid fiber or the like can be used.

  In the membrane electrode assembly 110, the anode-side gas diffusion layer 140 is bonded so that the highly water-repellent diffusion layer 146 contacts the anode-side catalyst layer 130. By doing so, it is possible to improve the hydrogen diffusibility at the interface between the anode-side gas diffusion layer 140 and the anode-side catalyst layer 130 and to improve the efficiency of supplying hydrogen to the anode-side catalyst layer 130. As a result, the power generation efficiency of the fuel cell stack 10 can be improved.

  In the anode-side gas diffusion layer 140, the hydrophilic fibers 148 are formed such that when the membrane electrode assembly 110 and the separator 170 are brought into contact with each other, the rib portions 172 of the separator 170 and a part of the hydrophilic fibers 148 Are sewed on the diffusion layer base material 142 so as to be in contact with each other. As described above, the surface of the rib portion 172 has been subjected to a hydrophilic treatment. Further, the rib portion 172 is formed of a porous material. Therefore, the generated water that is generated in the cathode side catalyst layer 150 during power generation, permeates the electrolyte membrane 120, and exudes to the anode side catalyst layer 130 is formed on the surface of the anode side gas diffusion layer 140 along the hydrophilic fibers 148. It moves quickly, spreads to the surface and inside of the rib portion 172, and is discharged to the outside together with the anode off gas. As a result, flooding on the anode side of the membrane electrode assembly 110 can be suppressed.

C2. Cathode side gas diffusion layer:
FIG. 4 is an explanatory diagram schematically showing a cross-sectional structure of the cathode-side gas diffusion layer 160 of the membrane electrode assembly 110. Further, in this drawing, the arrangement relationship between the cathode-side gas diffusion layer 160 and the separator 180 when the membrane electrode assembly 110 and the separator 180 are brought into contact with each other, and the electrolyte membrane 120 in the membrane electrode assembly 110. The arrangement relationship is also shown.

  As shown in the figure, the cathode-side gas diffusion layer 160 includes a low water-repellent diffusion layer 164 having a relatively low water repellency and a high water-repellent diffusion layer 166 having a relatively high water repellency, like the anode-side gas diffusion layer 140. A hydrophilic fiber 168 having hydrophilicity is sewed on a diffusion layer base material 162 having a surface of the diffusion layer base material 162 so that a part thereof is exposed on both surfaces. The hydrophilic fibers 168 are sewn so as to penetrate in a direction perpendicular to the surface of the diffusion layer base material 162. The material and the like of the diffusion layer base material 162 and the hydrophilic fiber 168 are the same as those of the diffusion layer base material 142 and the hydrophilic fiber 148 described above.

  In the membrane electrode assembly 110, the cathode-side gas diffusion layer 160 is bonded so that the highly water-repellent diffusion layer 166 contacts the cathode-side catalyst layer 150 in the same manner as the anode-side gas diffusion layer 140. By doing so, the diffusibility of air at the interface between the cathode-side gas diffusion layer 160 and the cathode-side catalyst layer 150 can be improved, and the supply efficiency of oxygen to the cathode-side catalyst layer 150 can be improved. As a result, the power generation efficiency of the fuel cell stack 10 can be improved.

  In the cathode-side gas diffusion layer 160, the hydrophilic fibers 168 are exposed so that the hydrophilic fibers 168 are exposed in the groove portions 184 of the separator 180 when the membrane electrode assembly 110 and the separator 180 are brought into contact with each other. The diffusion layer base material 162 is sewn. Then, as described above, dry air flows through the groove portion 184 of the separator 180. Therefore, the generated water generated in the cathode side catalyst layer 150 during power generation moves to the surface of the cathode side gas diffusion layer 160 along the hydrophilic fiber 148, and is dried by dry air and discharged to the outside together with the cathode off gas. Is done. As a result, flooding on the cathode side of the membrane electrode assembly 110 can be suppressed.

  In the anode side gas diffusion layer 140 and the cathode side gas diffusion layer 160 described above, the hydrophilic fibers 148 and 168 are in contact with the surfaces of the anode side gas diffusion layer 140 and the cathode side gas diffusion layer 160, respectively. Since it is sewn so as to penetrate in the vertical direction, the anode side gas diffusion layer 140 and the cathode side gas diffusion layer are formed at the shortest distance from the anode side catalyst layer 130 and the cathode side catalyst layer 150. 160 can be moved to the surface.

  The anode-side gas diffusion layer 140 and the cathode-side gas diffusion layer 160 are marked so that alignment with the separators 170 and 180 can be easily performed.

C3. Manufacturing method of gas diffusion layer:
Since the diffusion layer base materials 142 and 162 are relatively easily damaged, the anode-side gas diffusion layer 140 and the cathode-side gas diffusion layer 160 described above are manufactured by, for example, the manufacturing method described below. Here, the manufacturing method of the anode side gas diffusion layer 140 will be described, but the manufacturing method of the cathode side gas diffusion layer 160 is also the same.

  FIG. 5 is an explanatory view showing an example of a method for manufacturing the anode-side gas diffusion layer 140. First, the diffusion layer base material 142, the hydrophilic fiber 148, and the hollow needle 200 for sewing the hydrophilic fiber 148 to the diffusion layer base material 142 are prepared. And the marking for aligning the anode side gas diffusion layer 140 and the separator 170 is attached to the diffusion layer base material 142. And as shown to Fig.5 (a), the hollow needle 200 is stuck in the desired position of the diffusion layer base material 142 vertically. Then, as shown in FIG. 5B, the hydrophilic fiber 148 is passed through the hollow needle 200. Then, as shown in FIG. 5C, the hollow needle 200 through which the hydrophilic fiber 148 has passed is pulled out from the diffusion layer base material 142. And the process shown to Fig.5 (a)-(c) is repeated until the hydrophilic fiber 148 is sewn on the desired position of the diffusion layer base material 142 entirely. By doing so, the anode-side gas diffusion layer 140 can be manufactured.

  In the fuel cell stack 10 of the present embodiment described above, the hydrophilic fibers 148 and 168 are sewn to the diffusion layer base materials 142 and 162 in the anode side gas diffusion layer 140 and the cathode side gas diffusion layer 160. The hydrophilic fibers 148 and 168 can be accurately arranged at desired positions on the surfaces of the side gas diffusion layer 140 and the cathode side gas diffusion layer 160. Since some of the hydrophilic fibers 148 and 168 are exposed on both surfaces of the diffusion layer base materials 142 and 162, respectively, the hydrophilic fibers 148 are exposed from the anode side catalyst layer 130 and the cathode side catalyst layer 150, respectively. , 168, the generated water can be quickly moved to the surfaces of the anode side gas diffusion layer 140 and the cathode side gas diffusion layer 160. Therefore, in the fuel cell stack 10, the generated water generated by the electrochemical reaction between hydrogen and oxygen is converted from the anode side catalyst layer 130 and the cathode side catalyst layer 150 to the anode side gas diffusion layer 140 and the cathode side gas. It can be moved to a desired position on the surface of the diffusion layer 160. The generated water can be quickly discharged to the outside of the fuel cell stack 10 together with the anode offgas or the cathode offgas offgas. As a result, flooding in the fuel cell stack 10 can be suppressed.

D. 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.

D1. Modification 1:
In the above embodiment, the anode-side gas diffusion layer 140 includes the diffusion layer base material 142 and the hydrophilic fibers 148, but is not limited thereto. As described above, since the diffusion layer base material 142 is easily damaged, a reinforcing thread 149 for reinforcement when the diffusion layer base material 142 is sewn may be further provided. The same applies to the cathode side gas diffusion layer 160.

  FIG. 6 is an explanatory diagram schematically showing a cross-sectional structure of an anode-side gas diffusion layer as a modification. As shown in FIG. 6A, a reinforcing thread 149 is arranged on the gas flow path side of the diffusion layer base material 142, and one hydrophilic fiber 148 is sewn at a desired position across the reinforcing thread 149. You may do it. Further, as shown in FIG. 6B, a reinforcing thread 149 is disposed on the gas flow path side of the diffusion layer base material 142, and a plurality of hydrophilic fibers 148 are sewn across the reinforcing thread 149. Also good. In this case, the remaining hydrophilic fiber 148 on the anode side catalyst layer 130 side is pasted along the surface of the diffusion layer base material 142. Further, as shown in FIG. 6C, similarly to the example shown in FIG. 6B, the reinforcing yarn 149 is disposed on the gas flow path side of the diffusion layer base material 142 and straddles the reinforcing yarn 149. A plurality of hydrophilic fibers 148 are sewn so that the remaining hydrophilic fibers 148 on the anode-side catalyst layer 130 side are loosened, and are spread and pasted along the surface of the diffusion layer base material 142. May be. Further, the reinforcing thread 149 in FIGS. 6B and 6C may be omitted.

D2. Modification 2:
In the above embodiment, the anode gas diffusion layer 140 includes the low water repellency diffusion layer 144 and the high water repellency diffusion layer 146, but may include only one of them. The same applies to the cathode side gas diffusion layer 160.

D3. Modification 3:
In the above embodiment, in the anode side gas diffusion layer 140, the hydrophilic fibers 148 are sewn perpendicularly to the surface of the diffusion layer base material 142, but may be sewn diagonally.

D4. Modification 4:
In the above embodiment, the rib portion 172 of the separator 170 is formed of a porous body, but may not be a porous body.

D5. Modification 5:
In the above embodiment, the separator 170 in contact with the anode side of the membrane electrode assembly 110 and the separator 180 in contact with the cathode side are different from each other. However, the present invention is not limited to this. For example, a separator 170 may be used instead of the separator 180 as a separator that contacts the cathode side of the single cell 100. In this case, the method for sewing the hydrophilic fibers 168 to the diffusion layer base material 162 in the cathode side gas diffusion layer 160 is the same as the method for sewing the hydrophilic fibers 148 to the diffusion layer base material 142 in the anode side gas diffusion layer 140. May be.

  In the above embodiment, dry air is supplied to the cathode of the membrane electrode assembly 110. However, humidified air may be supplied. In this case, since the generated water that has moved to the surface of the cathode-side gas diffusion layer 160 cannot be dried, the separator 170 is used instead of the separator 180 and the diffusion layer in the cathode-side gas diffusion layer 160 is used. The method for sewing the hydrophilic fibers 168 to the base material 162 (arrangement relationship with the separator 170) may be the same as the method for sewing the hydrophilic fibers 148 to the diffusion layer base material 142 in the anode-side gas diffusion layer 140. preferable.

D6. Modification 6:
In the above embodiment, in the example shown in FIG. 3, in the anode side gas diffusion layer 140, the hydrophilic fiber 148 is sewn in a direction crossing the plurality of rib portions 172 of the separator 170. It is not limited to this. For example, the hydrophilic fiber 148 may be sewn in the direction in which one rib portion 172 is longitudinally cut. The same applies to the cathode side gas diffusion layer 160.

D7. Modification 7:
In the above embodiment, the case where the gas diffusion layer of the present invention is applied to both the anode side and the cathode side of the membrane electrode assembly 110 has been described. However, the present invention is not limited to this. For example, the gas diffusion layer of the present invention may be applied only to the cathode side where the amount of generated water increases.

It is explanatory drawing which shows schematic structure of the fuel cell stack 10 as one Example of this invention. 3 is an explanatory diagram schematically showing a cross-sectional structure of a single cell 100. FIG. 4 is an explanatory diagram schematically showing a cross-sectional structure of an anode-side gas diffusion layer 140 of a membrane electrode assembly 110. FIG. 3 is an explanatory diagram schematically showing a cross-sectional structure of a cathode-side gas diffusion layer 160 of a membrane electrode assembly 110. FIG. 5 is an explanatory view showing an example of a method for producing an anode side gas diffusion layer 140. FIG. It is explanatory drawing which shows typically the cross-section of the anode side gas diffusion layer as a modification.

Explanation of symbols

10 ... Fuel cell stack 12, 14 ... End plate 16, 22 ... Insulating plate 18, 20 ... Current collector plate 19, 21 ... Output terminal 31 ... Cooling water supply port 32. .. Cooling water discharge port 33 ... Oxidant gas supply port 34 ... Oxidant gas discharge port 35 ... Fuel gas supply port 36 ... Fuel gas discharge port 100 ... Single cell 110 ... Membrane / electrode assembly 120 ... electrolyte membrane 130 ... anode side catalyst layer 140 ... anode side gas diffusion layer 142 ... diffusion layer substrate 144 ... low water repellency diffusion layer 146 ... high repellency Aqueous diffusion layer 148 ... hydrophilic fiber 150 ... cathode side catalyst layer 160 ... cathode side gas diffusion layer 162 ... diffusion layer substrate 164 ... low water repellency diffusion layer 166 ... high repellency Aqueous diffusion layer 168 ... hydrophilic fiber 170 ... separator 172 ... rib 174 ... groove 180 ... separator 182 ... rib 184 ... groove 200 ... hollow needle

Claims (7)

A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And the gas diffusion layer used in a fuel cell comprising a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
A diffusion layer substrate having water repellency;
A hydrophilic fiber having hydrophilicity,
The hydrophilic fiber is sewn to the diffusion layer substrate so that a part of the hydrophilic fiber is exposed on both sides of the diffusion layer substrate.
Gas diffusion layer. The gas diffusion layer according to claim 1,
The diffusion layer base material includes a low water-repellent layer having relatively low water repellency and a high water-repellent layer having relatively high water repellency,
The highly water repellent layer is provided on a surface in contact with the catalyst layer,
Gas diffusion layer. The gas diffusion layer according to claim 1 or 2,
The hydrophilic fiber is sewn so as to penetrate in a direction perpendicular to the surface of the diffusion layer substrate.
Gas diffusion layer. A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
The membrane electrode assembly includes the gas diffusion layer according to any one of claims 1 to 3 as the gas diffusion layer,
The fuel cell includes a separator that sandwiches both surfaces of the membrane electrode assembly,
The separator is
A rib portion in contact with the gas diffusion layer;
A groove portion serving as a gas flow path through which the gas flows,
At least the surface of the rib part has hydrophilicity,
In the gas diffusion layer, the hydrophilic fiber is sewn to the diffusion layer base material so that a part of the hydrophilic fiber is in contact with the rib portion.
Fuel cell. The fuel cell according to claim 4, wherein
The rib portion is made of a porous member.
Fuel cell. A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
The membrane electrode assembly includes the gas diffusion layer according to any one of claims 1 to 3 as the gas diffusion layer,
The fuel cell includes a separator that sandwiches both surfaces of the membrane electrode assembly,
The separator is
A rib portion in contact with the gas diffusion layer;
A groove portion serving as a gas flow path through which the gas flows,
The gas flow path is a gas flow path through which the dried gas flows,
In the gas diffusion layer, the hydrophilic fiber is sewn to the diffusion layer substrate so that a part of the hydrophilic fiber is exposed to the gas flow path.
Fuel cell. A catalyst layer comprising a membrane electrode assembly in which an anode and a cathode are joined to both surfaces of a predetermined electrolyte membrane, and the cathode is joined to the electrolyte membrane to promote an electrochemical reaction between hydrogen and oxygen And a gas diffusion layer for use in a fuel cell comprising a gas diffusion layer for supplying a predetermined gas while diffusing the catalyst layer,
Preparing a diffusion layer substrate having water repellency;
Preparing a hydrophilic fiber having hydrophilicity;
Sewing the hydrophilic fibers to the diffusion layer substrate so that a part of the hydrophilic fibers are exposed on both surfaces of the gas diffusing substrate;
A manufacturing method comprising:

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