JP4087766B2 - Gas diffusion member, method for manufacturing gas diffusion member, fuel cell - Google Patents

Description

  The present invention relates to a gas diffusion member mounted on a fuel cell and a fuel cell including the gas diffusion member.

  The fuel cell is generally disposed on the opposite side of the electrolyte membrane, the catalyst layer for the fuel electrode disposed on one side in the thickness direction of the electrolyte membrane, and the catalyst layer for the fuel electrode. Gas diffusion member for fuel electrode, gas flow distribution plate for fuel electrode arranged on the opposite side of electrolyte membrane among gas diffusion member for fuel electrode, and oxidant arranged on the other side in the thickness direction of the electrolyte membrane A catalyst layer for the electrode, a gas diffusion member for the oxidant electrode disposed on the opposite side of the catalyst layer for the oxidant electrode, and a side opposite to the electrolyte membrane of the gas diffusion member for the oxidant electrode And a gas flow plate for the oxidant electrode disposed in the.

  During power generation of the fuel cell, the fuel is sent to the fuel electrode catalyst layer through the fuel electrode gas flow plate and the fuel electrode gas diffusion member. The oxidant gas containing oxygen is sent to the catalyst layer for the oxidant electrode through the gas flow plate for the oxidant electrode and the gas diffusion member for the oxidant electrode. When the fuel reaches the catalyst layer on the fuel electrode side, protons and electrons are generated by a catalytic reaction. Protons permeate the electrolyte membrane and migrate to the oxidant electrode side. The electrons are transferred to the oxidant electrode side through a load by the external conductor. On the other hand, in the oxidizer electrode, protons that have passed through the electrolyte membrane from the fuel electrode side, electrons supplied through the external conductor, and oxygen react to generate water. In this way, a power generation reaction is performed.

  The water generated as described above is discharged mainly through the gas diffusion member on the oxidizer electrode side, and part of the water passes through the electrolyte membrane and is discharged through the gas diffusion member on the fuel electrode side. However, unless water is efficiently discharged, the gas passage in the gas diffusion member is blocked with water, gas permeability is hindered, and satisfactory power generation performance cannot be obtained. In particular, because water is generated by the power generation reaction at the oxidizer electrode, if water is not efficiently discharged, the gas passage in the gas diffusion member is blocked with water, gas permeability is hindered, and satisfactory power generation performance Cannot be obtained.

  Since the gas diffusion member described above has substantially the same physical property structure in this plane, the water discharge property tends to be insufficient on the gas outlet side where water is likely to accumulate, compared to the gas inlet side. As a result, on the gas outlet side, the gas passage is blocked by water condensed at the boundary between the gas diffusion member and the catalyst layer, and the gas diffusibility is likely to deteriorate. If the fuel cell operating conditions (gas humidification condition, gas temperature, etc.) are set so that the gas diffusibility does not decrease on the gas outlet side, water clogging on the gas outlet side can be suppressed. The electrolyte membrane is easily dried on the inlet side, the proton conductivity of the electrolyte membrane is lowered, and it is difficult to obtain satisfactory power generation performance.

  In the fuel cell, the active material of the fuel gas described above is consumed by the power generation reaction, and therefore gradually decreases from the upstream side to the downstream side of the fuel gas. Similarly, since the active material of the oxidant gas is consumed by the power generation reaction, it gradually decreases from the upstream side to the downstream side of the oxidant gas. For this reason, the concentration of the active material is lower in the downstream region of the gas than in the upstream region of the gas, and the active material is less likely to be supplied. For this reason, power generation reaction unevenness may occur between the gas inlet side and the gas outlet side.

  As a technique for preventing a decrease in gas diffusibility on the gas outlet side as described above, in Patent Documents 1 to 5, the gas permeability in the gas diffusion member is gradually increased from the gas inlet side toward the gas outlet side. What is to be raised is known.

  In Patent Document 1, in a fuel cell, a current collector having a diffusing function is formed of carbon cloth, and the mesh of the carbon cloth is gradually roughened from the gas inlet toward the gas outlet, so that the gas is more than the gas inlet side. A technique for improving gas diffusibility on the outlet side is disclosed. Patent Document 2 discloses a technique in which the gas permeability of the portion near the gas inlet in the gas diffusion member is made smaller than the portion near the gas outlet. In this case, the porosity and thickness of the gas diffusion member are controlled.

  Patent Document 3 discloses a technique in which the gas diffusibility on the oxidant gas supply side is lower than the gas diffusibility on the oxidant gas discharge side in the gas diffusion member of the fuel cell. In Patent Document 4, a water repellent containing PTFE is partially attached to the anode gas diffusion member by post-processing, and the moisture permeability of the first region on the gas inlet side of the anode gas diffusion member is measured on the gas outlet side. A technique for improving the moisture permeability of the second region is disclosed. Patent Document 5 discloses a technique for increasing the water repellency and maintaining the wettability of the solid electrolyte membrane by increasing the fluororesin content in the front part of the gas diffusion member on the cathode side of the fuel cell than in the rear part. ing.

Patent Document 6 discloses a technique in which a mixed layer composed of a fluororesin and carbon black is formed between a catalyst layer and a gas diffusion member, and the thickness of the mixed layer is changed at the inlet and outlet of the reaction gas. ing. In this case, the thickness of the mixed layer is set to be thick on the gas inlet side and thin on the gas outlet side. Patent Document 6 also discloses a technique for reducing the porosity of the mixed layer on the reaction gas inlet side and increasing it on the reaction gas outlet side.
JP-A-8-124583 JP-A-11-154523 Japanese Patent Laid-Open No. 2001-6698 JP 2001-236976 A Japanese Patent Laid-Open No. 2001-6708 JP 2001-135326 A

  According to the above-described publication technique, water discharge performance in the downstream region on the gas outlet side can be ensured, but there is a limit in suppressing drying of the electrolyte membrane in the upstream region.

  The present invention has been made in view of the above circumstances, and by adopting a multilayer structure including a rough layer having a relatively high gas permeability and a dense layer having a relatively low gas permeability, Supply of active material in the downstream region on the gas outlet side can be ensured by the fine permeation holes in the dense layer while the drying of the electrolyte membrane in the region is suppressed by the dense layer, and the water drainage in the downstream region on the gas outlet side can be secured. It is an object of the present invention to provide a gas diffusion member, a method for manufacturing the gas diffusion member, and a fuel cell that are advantageous to the above.

In the gas diffusion member according to aspect 1, the gas permeability and conductivity are such that one side in the thickness direction faces the catalyst layer, the other side in the thickness direction faces the gas distribution plate, and the gas in the gas distribution plate is sent to the catalyst layer. In a gas diffusion member having
A multi-layer structure having a coarse layer facing the gas distribution plate and having a relatively low density; and a dense layer facing the catalyst layer and having a relatively higher density than the coarse layer;
When the gas outlet side in the surface direction of the gas diffusion member is the gas downstream region,
At least in the gas downstream region, a minute transmission hole formed by irradiation of a high energy density beam or insertion of a needle-like member is formed in a dense layer ,
The gas distribution plate has a gas bending region where the gas flow bends, and the micro permeation hole is formed in a dense layer of a portion of the gas diffusion member facing the gas distribution region of the gas distribution plate. It is characterized by this.

  In this case, a gas such as fuel gas or oxidant gas passes through the inside of the coarse layer of the gas diffusion member to reach the catalyst layer, and generates a power generation reaction by the catalyst of the catalyst layer. According to the aspect 1, the dense layer having a relatively higher density than the coarse layer is disposed between the coarse layer and the catalyst layer. Therefore, the gas flow from the coarse layer of the gas diffusion member toward the catalyst layer is regulated by the dense layer having a relatively high density. Similarly, the release of moisture on the electrolyte membrane side to the gas diffusion member side is also restricted. Therefore, it is advantageous to suppress the excessive drying of the solid electrolyte by the dense layer. According to the aspect 1, since the fine permeation holes are formed in the dense layer in the gas downstream region, the excess water on the catalyst layer side is discharged toward the gas diffusion member from the fine permeation holes of the dense layer. Although the diameter of a hole can be selected suitably, 10-200 micrometers and 20-100 micrometers can be illustrated, However, It is not limited to this. Although the depth of a hole can be selected suitably, it can illustrate 10 micrometers-the state which penetrates a gas diffusion member, the state which penetrates 10 micrometers-a dense layer, or 10-30 micrometers, but it is not limited to these. .

According to the gas diffusion member according to aspect 1 , the minute transmission hole is formed by irradiation with a high energy density beam or insertion of a needle-like member. When the minute transmission hole is formed by irradiation with the high energy density beam, the modification (carbonization) of the water repellent material in the vicinity of the peripheral part of the fine transmission hole proceeds, and the water repellency in the vicinity of the peripheral part of the minute transmission hole is lowered. For this reason, hydrophilicity increases in the peripheral part vicinity of a micro permeation | transmission hole. For this reason, it can contribute to discharge of water through the minute permeation hole. In addition, when the inner wall which forms a micro permeation | hole is rich in water repellency, discharge | emission of water through a micro permeation | transmission hole is easy to be restricted. Examples of the high energy density beam include a laser beam and an electron beam.

  On the other hand, when forming the minute transmission hole by inserting the needle-shaped member, the cross-sectional shape of the minute transmission hole can be easily changed by changing the sharpness angle of the insertion portion of the needle-shaped member.

According to the gas diffusion member according to aspect 1 , the number of minute permeation holes per unit area can be set larger in the gas downstream region than in the gas upstream region. In this case, the water discharge performance is improved in the downstream region of the gas. Moreover, the supply property of the active material to the catalyst layer is improved in the downstream region of the gas.

According to the gas diffusion member according to aspect 1 , it is preferable that the depth of the minute permeation hole is set deeper in the gas downstream region than in the gas upstream region. In this case, the water discharge performance is improved in the downstream region of the gas. Moreover, the supply property of the active material to the catalyst layer is improved in the downstream region of the gas.

According to the gas diffusion member according to aspect 1 , the gas flow distribution plate has a gas bending region in which the gas flow is bent, and in the portion of the gas diffusion member facing the gas flow distribution region of the gas flow distribution plate, A minute transmission hole is formed. In this case, in the gas song run region that bends the flow of gas out of the gas distribution plate, there is the water accumulation. Thus, also in the gas diffusion member comprises a gas in the scan tracks running around the area, property of easily water reservoir of the gas distribution plate. Therefore, by forming the fine through holes at a portion facing the region running gas song gas distribution plate of the gas diffusion member, the water discharge in the portion facing the region running gas song gas distribution plate of the gas diffusion member Sex is secured.

In the gas diffusion member manufacturing method according to aspect 2 , the one side in the thickness direction faces the catalyst layer, the other side in the thickness direction faces the gas flow distribution plate having the gas bending region in which the gas flow is bent , and the gas In the method of manufacturing a gas diffusion member having gas permeability and conductivity, which sends the gas of the flow distribution plate to the catalyst layer,
Sheet molding for forming a sheet having a multilayer structure having a coarse layer facing the gas flow plate and having a relatively low density, and a dense layer facing the catalyst layer and having a relatively higher density than the coarse layer Process,
By irradiating the dense layer with the high energy density beam, at least the dense layer of the sheet is formed such that a plurality of minute transmission holes are formed in a portion of the gas diffusion member facing the gas curved region of the gas flow distribution plate. And a hole forming step of forming the plurality of minute transmission holes.

  In this case, since the minute transmission holes are formed in the dense layer by irradiation with the high energy density beam, the water repellency is improved by the modification (carbonization) of the water repellent material in the vicinity of the peripheral portion of the minute transmission holes formed in the dense layer. Therefore, the vicinity of the peripheral edge of the minute permeation hole tends to have hydrophilicity. For this reason, it can contribute to discharge | emission of the water through the micro permeation | hole which was formed in the dense layer. In addition, when the peripheral part of a micro permeation | transmission hole is rich in water repellency, discharge of the water through a micro permeation | transmission hole is easy to be restricted.

  The sheet forming process described above includes forming a paper sheet based on carbon fiber and burned material by making a liquid material based on carbon fiber and burned material, and a void inside the paper sheet. An impregnation step of impregnating a water repellent material to obtain a base sheet, a heat treatment step of heat-treating the base sheet to burn off the burned-out material, and a coating step of applying a fluid containing a conductive substance to the base sheet after the heat treatment The form to include can be illustrated. Since the fluid containing the conductive material is applied to the surface of the base sheet, it is easy to form a multilayer structure in which a dense layer is laminated on the surface of the coarse layer.

According to aspect 2, if a micro permeation hole is formed in a portion of the gas diffusion member that faces the gas bending region of the gas flow distribution plate (having a property of easily collecting water), the gas flow distribution plate of the gas diffusion member is formed. Water discharge is ensured at the portion facing the gas bending region.

In the method of manufacturing the gas diffusion member according to aspect 3 , the one side in the thickness direction faces the catalyst layer, the other side in the thickness direction faces the gas flow distribution plate having the gas bending region where the gas flow is bent , and the gas In a manufacturing method for manufacturing a gas diffusion member having gas permeability and conductivity to send a gas of a flow distribution plate to a catalyst layer,
Sheet molding for forming a sheet having a multilayer structure having a coarse layer facing the gas flow plate and having a relatively low density, and a dense layer facing the catalyst layer and having a relatively higher density than the coarse layer Process,
By inserting the needle-like member into the dense layer, a plurality of minute permeation holes are formed in at least the dense layer of the sheet so that the gas diffusion member is formed in a portion facing the gas bending region of the gas distribution plate. And a hole forming step of forming a minute transmission hole.

  Since the minute transmission holes are formed by inserting the needle-like member, a plurality of minute transmission holes can be formed together. Further, if the sharpness angle of the insertion part of the needle-like member is changed, the cross-sectional shape of the minute transmission hole and the inclination angle of the inner wall surface of the minute transmission hole can be changed.

According to aspect 3, if a micro permeation hole is formed in a portion of the gas diffusion member that faces the gas bending region of the gas flow distribution plate (having a property of easily collecting water), the gas flow distribution plate of the gas diffusion member Water discharge is ensured at the portion facing the gas bending region.

A fuel cell according to aspect 4 includes an electrolyte membrane based on an electrolyte, a fuel electrode catalyst layer disposed on one side in the thickness direction of the electrolyte membrane, and a fuel electrode catalyst layer on a side opposite to the electrolyte membrane. The fuel electrode gas diffusion member, the fuel electrode gas flow distribution plate disposed on the opposite side of the fuel electrode gas diffusion member, and the oxidant disposed on the other side in the thickness direction of the electrolyte membrane An electrode catalyst layer, an oxidant electrode gas diffusion member disposed on the opposite side of the oxidant electrode catalyst layer, and an oxidant electrode gas diffusion member disposed on the opposite side of the electrolyte membrane. In a fuel cell comprising a gas distribution plate for an oxidant electrode,
At least one of the fuel electrode gas diffusion member and the oxidant electrode gas diffusion member is formed of the gas diffusion member according to any one of the above-described aspects.

In this case, a gas such as fuel gas or oxidant gas passes through the inside of the coarse layer of the gas diffusion member to reach the catalyst layer, and generates a power generation reaction by the catalyst of the catalyst layer. According to the aspect 4 , the dense layer having a relatively higher density than the coarse layer is disposed between the coarse layer and the catalyst layer. Therefore, the gas flow from the coarse layer of the gas diffusion member toward the catalyst layer is regulated by the dense layer having a relatively high density. Similarly, the release of moisture on the electrolyte membrane side to the gas diffusion member side is also restricted. Therefore, it is advantageous for suppressing the excessive drying of the solid electrolyte. According to the aspect 4 , since the minute permeation hole is formed in the dense layer in the gas downstream region, excess water on the catalyst layer side is discharged from the minute permeation hole of the dense layer toward the gas diffusion member.

  According to the present invention, by adopting a multilayer structure including a coarse layer and a dense layer, it is possible to ensure water discharge performance in the downstream region on the gas outlet side while suppressing drying of the electrolyte membrane in the upstream region. In addition, it is possible to provide a gas diffusion member, a gas diffusion member manufacturing method, and a fuel cell that are advantageous for supplying an active material in a downstream region on the gas outlet side.

According to the present invention, the gas flow distribution plate has a gas bending region in which the gas flow is bent, and a minute permeation hole is formed in a portion of the gas diffusion member facing the gas flow region of the gas flow distribution plate. Has been. In this case, water may accumulate in the gas bending region in which the gas flow is bent in the gas distribution plate. Therefore, the gas diffusing member also has the property that water tends to accumulate in the vicinity of the gas bending region in the gas flow plate. Therefore, if a micro permeation hole is formed in the portion of the gas diffusion member that faces the gas bending region of the gas flow plate, the water dischargeability in the portion of the gas diffusion member that faces the gas flow region of the gas flow plate is reduced. Secured.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. As shown in FIG. 1, the fuel cell includes an electrolyte membrane 1 based on a polymer-type solid electrolyte, and a fuel electrode catalyst layer 2 disposed on one side of the electrolyte membrane 1 in the thickness direction. The fuel electrode gas diffusion member 3 disposed on the opposite side of the fuel electrode catalyst layer 2 to the electrolyte membrane 1 and the fuel electrode gas diffusion member 3 disposed on the opposite side of the electrolyte membrane 1. The gas distribution plate 4 for the fuel electrode, the catalyst layer 5 for the oxidant electrode disposed on the other side in the thickness direction of the electrolyte membrane 1, and the electrolyte membrane 1 of the catalyst layer 5 for the oxidant electrode The gas diffusion member 6 for the oxidant electrode disposed on the opposite side of the gas diffusion member 6 and the gas flow distribution plate 7 for the oxidant electrode disposed on the opposite side of the electrolyte membrane 1 from the gas diffusion member 6 for the oxidant electrode. Have The gas distribution plate 7 for the oxidant electrode has a gas passage 7a through which an oxidant gas containing oxygen as an active material flows. The gas distribution plate 4 for the fuel electrode has a gas passage 4a through which a fuel gas such as hydrogen gas as an active material or a hydrogen-containing gas flows. The catalyst layers 2 and 5 carry a catalyst metal such as platinum.

  The gas diffusion member 6 for the oxidant electrode has gas permeability to send the oxidant gas containing oxygen flowing through the gas passage 7a of the gas flow plate 7 for the oxidant electrode to the catalyst layer 5 for the oxidant electrode. In the gas diffusion member 6 for the oxidant electrode, one side in the thickness direction faces the catalyst layer 5 for the oxidant electrode, and the other side in the thickness direction faces the gas passage 7a of the gas distribution plate 7 for the oxidant electrode. Yes. The gas diffusion member 3 for the fuel electrode has gas permeability to send the fuel gas flowing through the gas passage 4a of the gas flow plate 4 for the fuel electrode to the catalyst layer 2 for the fuel electrode. The gas diffusion member 3 for the fuel electrode is formed of an aggregate of carbon fibers, which are conductive fibers, and has conductivity. In the gas diffusion member 3 for the fuel electrode, one side in the thickness direction faces the catalyst layer 2 for the fuel electrode, and the other side in the thickness direction faces the gas passage 4a of the gas distribution plate 4 for the fuel electrode.

  FIG. 2 schematically shows a cross section of the gas diffusion member 6 for the oxidizer electrode. The gas diffusion member 6 for the oxidant electrode has a multi-layer structure, and includes a coarse layer 8 having gas permeability and conductivity, and a dense layer 9 that is relatively denser than the coarse layer 8 having conductivity. Have The thickness of the dense layer 9 is made thinner than the thickness of the coarse layer 8. Specifically, the thickness of the coarse layer 8 is set to about 200 to 300 μm, and the thickness of the dense layer 9 is set to about 10 to 80 μm. However, the present invention is not limited to this.

  The coarse layer 8 faces the gas passage 7a side of the gas flow plate 7 for the oxidant electrode. The density of the coarse layer 8 is set to be relatively lower than that of the dense layer 9 in order to increase gas permeability. The dense layer 9 is opposed to the catalyst layer 5 for the oxidant electrode, and the density is set relatively higher than that of the coarse layer 8. The coarse layer 8 is formed by using a carbon fiber aggregate having conductivity, a fluororesin as a water repellent material, and carbon black as a conductive material as a base material. The dense layer 9 does not contain carbon fibers, and is formed using a fluororesin as a water repellent material and carbon black as a conductive material as base materials.

According to this embodiment, since the dense layer 9 is provided between the coarse layer 8 and the catalyst layer 5 for the oxidant electrode, the following actions (1) to (3) can be expected. it can.
(1) The adhesion between the catalyst layer 5 and the gas diffusion member 6 for the oxidant electrode can be improved.
(2) Since the density of the dense layer 9 is relatively higher than that of the coarse layer 8, the hard carbon fiber constituting the coarse layer 8 is prevented from piercing the catalyst layer 5 for the oxidant electrode, and the catalyst layer 5 is damaged. Can be suppressed.
(3) Since the density of the dense layer 9 is higher than that of the coarse layer 8, drying of the solid electrolyte membrane 1, particularly drying in the upstream region of the solid electrolyte membrane 1 can be suppressed.

As shown in FIG. 2, in the dense layer 9 constituting the gas diffusion member 6 for the oxidizer electrode, a minute permeation hole 10 is formed at least in the gas downstream region. Then, in the dense layer 9, a gas inlet side or al, toward the gas under flow region is a gas outlet side, that is, is formed so that the number of fine through holes 10 toward the direction of the arrow X1 increases . In other words, when the pitch is the distance between the micro through holes 10 of adjacent set is P, the pitch P is the gas inlet side or al, toward the gas outlet side (gas downstream region), that is, toward the direction of the arrow X1 It is set to become smaller as it goes. As a result, the number of minute permeation holes 10 per unit area is set larger in the gas downstream region than in the gas upstream region. As a result, in the gas downstream region, water existing between the catalyst layer 5 for the oxidant electrode and the dense layer 9 can be easily discharged to the coarse layer 8, and the water discharging property is improved. In addition, in the gas downstream region where the concentration of the active material contained in the gas is lowered, the supply ability of the active material from the coarse layer 8 toward the catalyst layer 5 for the oxidant electrode is improved.

The minute transmission hole 10 is formed by post-processing by laser beam irradiation. Examples of the laser beam include a YAG laser beam and a CO ₂ laser beam. When the minute transmission hole 10 is formed by laser beam irradiation, the modification (carbonization) of the fluororesin (PTFE resin), which is a water-repellent material, in the vicinity of the peripheral part of the micro transmission hole 10 proceeds, and the peripheral part of the micro transmission hole 10 The water repellency in the vicinity decreases. For this reason, the hydrophilicity increases in the vicinity of the peripheral portion of the minute transmission hole 10 as shown in a test example described later. Therefore, in the gas downstream region, it is possible to contribute to discharging the oxidant electrode catalyst layer 5 side to the coarse layer 8 side through the minute permeation hole 10. In addition, when the peripheral part of the micro permeation | transmission hole 10 is rich in water repellency, discharge of the water through the micro permeation | transmission hole 10 is easy to be restricted. When the minute transmission hole 10 is formed with a laser beam, the minute transmission hole 10 is advantageous for increasing the diameter of the incident side of the laser beam. As a result, as shown in FIG. 2, it is advantageous to increase the diameter D1 of the minute permeation hole 10 on the side of the catalyst layer 5 for the oxidant electrode. In this case, it is advantageous for promoting the discharge of water.

  According to the present embodiment, the plurality of minute transmission holes 10 are formed in the dense layer 9 of the gas diffusion member 6 for the oxidant electrode so as to face the catalyst layer 5 for the oxidant electrode. The peripheral edge of the film is more hydrophilic than the part where the micro-permeation holes 10 are not formed because the water repellency of the water repellent material is lowered and the water repellent material is modified (carbonized) by the laser beam irradiation. Is relatively high. As described above, since the peripheral portion of the micro permeation hole 10 and the inner wall surface of the perimeter portion are relatively highly hydrophilic, the permeation of excess water interposed between the dense layer 9 and the catalyst layer 5 for the oxidant electrode is micro permeate. It is advantageous for discharging to the coarse layer 8 side through the hole 10.

  Further, in the gas diffusion member 6 for the oxidant electrode, the portion where the minute transmission hole 10 is not formed, that is, the portion of the adjacent minute transmission hole 10 is not irradiated with the laser beam, and the water repellent material. Therefore, water repellency is relatively high. For this reason, in the part of the small permeable hole 10 provided adjacently, it is advantageous for suppressing that the space | gap part used as a gas passageway of the gas diffusion member 6 for oxidant electrodes is clogged with water by the water-repellent function. .

  According to the present embodiment, as shown in FIG. 2, the minute transmission holes 10 are formed in the dense layer 9, but the minute transmission holes 10 are not substantially formed in the coarse layer 8. In this case, if the output of the laser beam is adjusted, the minute transmission hole 10 can be formed in the dense layer 9 but not in the coarse layer 8. In some cases, the minute transmission hole 10 may reach the rough layer 8 from the dense layer 9.

  The manufacturing method of the gas diffusion member 6 for the oxidant electrode described above will be described. First, a sheet forming process is performed. That is, a liquid material is prepared in which carbon fiber and a burned-out substance (pulp fiber or the like) that burns down when heated are dispersed in water. By making paper of this liquid material, a papermaking sheet based on carbon fiber and burned-out material (pulp fiber or the like) is formed. A base sheet is obtained by impregnating a paste-like first fluid mainly comprising a water-repellent material (fluororesin) and a powdered conductive material (carbon black or the like). Next, the base sheet is heated in the atmosphere (oxygen-containing atmosphere) at a temperature T1 (for example, 350 to 390 ° C.) and heat-treated to burn off the burnt material (pulp and the like). As a result, voids, which are burnt-out traces of the burned-out substance, are formed inside the base sheet. Next, a paste-like second fluid mainly containing a water-repellent material (fluororesin) and a powdered conductive material (carbon black or the like) is applied to the surface of the base sheet. A water repellent material, a conductive material, or the like is loaded in the hollow portion. Next, the base sheet is fired in the atmosphere at a temperature T2 (for example, 300 to 360 ° C.). Thereby, the gas diffusion member 6 composed of the coarse layer 8 and the dense layer 9 is formed. Note that temperature T1> temperature T2, temperature T1≈temperature T2, and temperature T1 <temperature T2. Similarly, the gas diffusion member 3 for the fuel electrode is formed of the coarse layer 8 and the dense layer 9. This completes the sheet forming process.

  Next, a hole forming step is performed. That is, a laser oscillator is positioned above the gas diffusion member 6 for the oxidant electrode, and the laser beam oscillated from the laser oscillator is irradiated on the dense layer 9 of the gas diffusion member 6 for the oxidant electrode in a scattered manner. To do. Thereby, a plurality of minute transmission holes 10 are formed on the surface of the dense layer 9. The output of the laser beam, the spot diameter, etc. can be selected as appropriate.

(Application form)
FIG. 3 shows a form to which the first embodiment is applied . The gas distribution plate 7 shown in FIG. 3 is for the oxidizer electrode and has a partition wall 7b. The gas passage 7a partitioned by the partition wall 7b is set in a curved structure so as to form an inverted S shape. Accordingly, the oxidant gas flowing through the gas passage 7a of the gas flow distribution plate 7 for the oxidant electrode flows so as to bend in the reverse S-shape from the gas inlet toward the gas outlet, that is, from the gas upstream to the gas downstream. .

In FIG. 3, the mark “·” indicates the micro permeation hole 10 ( the micro permeation hole 10 is formed in a portion of the gas diffusion member facing the gas bending region of the gas flow distribution plate) . As shown in FIG. 3, the number NA of the micro permeation holes 10 per unit area in the gas upstream region UA is relatively small, and the number ND of the micro permeation holes 10 per unit area in the gas downstream region DA is It is relatively common. The number of holes NA can be, for example, 10 to 1000 holes / cm ² , in particular about 750 holes / cm ² . The number of holes ND is, for example, 100 to 5000 / cm ² , particularly about 5000 / cm ² . However, the number of fine transmission holes 10 per unit area is not limited to this.

(Embodiment 2)
FIG. 4 shows a second embodiment. The second embodiment basically has the same configuration and effect as the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment. As shown in FIG. 4, the gas diffusion member 6 for the oxidant electrode has a multilayer structure, and a coarse layer 8 having a relatively low density and a dense layer having a relatively higher density than the coarse layer 8. 9. As shown in FIG. 4, in the dense layer 9, the micro permeation hole 10 is formed at least in the gas downstream region. Then, in the dense layer 9, a gas inlet side or al, toward the gas outlet side (gas downstream region), that is, toward the direction of the arrow X1, is formed such that the depth of the minute through holes 10 is increased Yes.

In other words, when the depth of the minute through holes 10 and h, depth h, the gas inlet side or al, toward the gas outlet side (gas downstream region), that is, to be deeper toward the direction of the arrow X1 Is set. As a result, in the gas downstream region, the exhaustability for discharging the water existing between the catalyst layer 5 for the oxidant electrode and the dense layer 9 to the coarse layer 8 is improved. Further, in the gas downstream region, the supply capability of the active material contained in the gas from the coarse layer 8 toward the oxidant electrode catalyst layer 5 is improved. The minute transmission hole 10 is formed by laser beam irradiation. Since the minute transmission hole 10 is formed by irradiation with the laser beam 20, the modification (carbonization) of the fluororesin that is a water-repellent material in the vicinity of the peripheral portion of the micro transmission hole 10 proceeds, and the vicinity of the peripheral portion of the micro transmission hole 10. Water repellency decreases. For this reason, hydrophilicity increases in the vicinity of the peripheral edge of the minute transmission hole 10. For this reason, it can contribute to discharge of water through the minute permeation hole 10. In general, when the depth h of the minute transmission hole 10 is large, the diameter of the minute transmission hole 10 is increased, and when the depth h of the minute transmission hole 10 is shallow, the diameter of the minute transmission hole 10 is decreased. Tend to be obtained. According to the present embodiment, the minute transmission holes 10 are formed in the dense layer 9, but the minute transmission holes 10 are not substantially formed in the coarse layer 8.

(Embodiment 3)
FIG. 5 shows a third embodiment. The third embodiment basically has the same configuration and effect as the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment. FIG. 5 shows a cross section of the gas diffusion member 6 for the oxidant electrode. The gas diffusion member 6 for the oxidant electrode has a multilayer structure, and has a coarse layer 8 having a relatively low density and a dense layer 9 having a relatively higher density than the coarse layer 8. The coarse layer 8 is formed by using a carbon fiber aggregate having conductivity, a fluororesin as a water repellent material, and carbon black as a conductive material as a base material. The dense layer 9 does not contain carbon fibers, and is formed using a fluororesin as a water repellent material and carbon black as a conductive material as base materials.

As shown in FIG. 5, in the dense layer 9, the micro permeation hole 10 is formed at least in the gas downstream region. Then, in the dense layer 9, a gas inlet side or al, toward the gas outlet side (gas downstream region), that is, the number of minute through holes 10 are formed so as to increase toward the direction of arrow X1. In other words, when the pitch is the distance between the micro through holes 10 and P, the pitch P is the gas inlet side or al, toward the gas outlet side (gas downstream region), that is, it becomes smaller toward the direction of the arrow X1 Is set to As a result, the number of minute permeation holes 10 per unit area is set larger in the gas downstream region than in the gas upstream region. As a result, in the gas downstream region, the water between the catalyst layer 5 for the oxidant electrode and the dense layer 9 can be easily discharged to the coarse layer 8, and the water discharge performance is improved. In addition, in the gas downstream region where the concentration of the active material contained in the gas is lowered, the supply ability of the active material from the coarse layer 8 toward the catalyst layer 5 for the oxidant electrode is improved.

According to the embodiment shown in FIG. 5, the minute transmission hole 10 is formed by inserting the needle-like member 25. In this case, as shown in FIG. 6, a holder 26 holding a plurality of needle-like members 25 on one surface side 26a is used, and the holder 26 is disposed above the dense layer 9 of the gas diffusion member 6 for the oxidant electrode. The holder 26 and the gas diffusion member 6 are brought closer to each other. As a result, the needle-like member 25 of the holder 26 is inserted into the dense layer 9 of the gas diffusion member 6, so that the plurality of minute transmission holes 10 can be formed together. Since the needle-like member 25 is inserted, the diameter of the minute transmission hole 10 is advantageous for increasing the entrance side of the needle-like member 25 in the minute transmission hole 10. As a result, as shown in FIG. 5, it is advantageous to increase the diameter D1 on the catalyst layer 5 side in the minute permeation hole 10. Moreover, if the sharp angle θ1 of the insertion part of the needle-like member 25 is changed, the cross-sectional shape of the minute transmission hole 10 formed in the dense layer 9 and the inclination angle θ2 of the peripheral portion of the minute transmission hole 10 can be easily changed. Can do.

  According to the present embodiment, the minute transmission holes 10 are formed in the dense layer 9, but the minute transmission holes 10 are not substantially formed in the coarse layer 8. In this case, as shown in FIG. 6, a stopper 27 capable of contacting the holder is appropriately provided, and the stopper 27 and the holder 26 are brought into contact with each other, thereby adjusting the insertion amount of the needle-like member 25, and the minute transmission hole 10. Is formed only in the dense layer 9.

FIG. 7 shows a form to which the above embodiment is applied. The gas passage 7a of the gas distribution plate 7 for the oxidant electrode shown in FIG. 7 is partitioned by a partition wall 7b, and has a curved structure so as to form an inverted S shape. Therefore, the oxidant gas flowing through the gas passage 7a of the gas flow distribution plate 7 for the oxidant electrode flows so as to bend in the reverse S-shape from the gas inlet toward the gas outlet. As shown in FIG. 7, the micro permeation | transmission hole 10 is formed in the curved structure. The number NA of the micro permeation holes 10 per unit area in the gas upstream region UA2 is relatively small. The number ND of the minute permeation holes 10 per unit area in the gas downstream region DA2 is relatively large. The number of holes NA can be, for example, 10 to 500 holes / cm ² , especially about 300 holes / cm ² . The number of holes ND is, for example, 400 to 1000 holes / cm ² , especially about 750 holes / cm ² . However, the number of fine transmission holes 10 per unit area is not limited to this.

(Embodiment 4)
FIG. 8 shows a fourth embodiment. The fourth embodiment has the same configuration and effect as the third embodiment. Hereinafter, a description will be given centering on differences from the third embodiment. As shown in FIG. 8, the gas diffusion member 6 for the oxidant electrode has a multi-layer structure, and a coarse layer 8 having a relatively low density and a dense layer having a relatively higher density than the coarse layer 8. 9. As shown in FIG. 8, in the dense layer 9, the micro permeation hole 10 is formed at least in the gas downstream region. Then, in the dense layer 9, a gas inlet side or al, toward the gas outlet side (gas downstream region), that is, toward the direction of arrow X1, is formed such that the depth h of the minute through holes 10 is increased ing. As a result, in the gas downstream region, the water between the catalyst layer 5 for the oxidant electrode and the dense layer 9 can be easily discharged to the coarse layer 8, and the water discharge performance is improved. In addition, in the gas downstream region where the concentration of the active material contained in the gas is lowered, the supply ability of the active material from the coarse layer 8 toward the catalyst layer 5 for the oxidant electrode is improved.

  The minute transmission hole 10 is formed by inserting a plurality of needle-like members 25 into the dense layer 9. According to the present embodiment, the minute transmission holes 10 are formed in the dense layer 9, but the minute transmission holes 10 are not substantially formed in the coarse layer 8.

(Embodiment 5)
FIG. 9 shows a fifth embodiment. The fifth embodiment basically has the same configuration and effect as the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment. As shown in FIG. 9, the tip of the minute transmission hole 10 formed in the dense layer 9 reaches the coarse layer 8. The minute transmission hole 10 is formed by laser beam irradiation or insertion of the needle-like member 25.

(Embodiment 6)
FIG. 10 shows a sixth embodiment. The sixth embodiment basically has the same configuration and effect as the first embodiment. Hereinafter, a description will be given centering on differences from the third embodiment. The gas passage 7a of the gas flow plate 7 has gas curved regions 74a and 74b in which the flow of the oxidant gas is bent. The gas bending regions 74a and 74b described above are generally portions where water tends to accumulate. Therefore, as shown in FIG. 10, in the curved regions 74a and 74b, the number of the small permeation holes 10 per unit area is the other part (the gas upstream region where the drying tends to occur or the gas flow where the gas flows straightly). It is set to be higher than the running area.

  As described above, in the gas diffusion member 6 for the oxidizer electrode, the number and / or the hole diameter of the micro permeation holes 10 per unit area are locally adjusted in the gas bending regions 74a and 74b in which water easily collects. By doing so, it is possible to locally adjust the water discharge ability and the supply ability of the active material, and the advantage that the power generation performance of the fuel cell can be improved is obtained.

Example 1
According to Example 1, a paper sheet made from carbon fibers (average diameter: 14 μm, average length: 3 mm) as conductive fibers and pulp fibers as burned-out substances was used. The papermaking sheet is formed by using a liquid material mainly composed of carbon fibers and pulp fibers and removing a liquid portion from the liquid material, and is an aggregate of carbon fibers and pulp fibers. Then, a paper sheet was impregnated by roll coating with a paste-like first fluid in which carbon black (Cabot Corp. Vulcan XC-72) and a water repellent material (PTFE dispersion Daikin Industries D-1) were dispersed. Next, the paper sheet was dried and then fired at a temperature T1 (380 ° C.). As a result, the pulp fiber was burned out and hollowed out, and a base sheet serving as the coarse layer 8 of the gas diffusion member 6 having a thickness of about 300 μm was formed.

  Furthermore, a paste-like second fluid in which carbon black (Cabot Corp. Vulcan XC-72) and a water repellent material (PTFE dispersion Daikin Industries D-1) were dispersed was further applied to the base sheet by roll coating. The second fluid forms the dense layer 9 and uses the same base material as the first fluid, but the blending ratio is different. Next, after drying, baking was performed at a temperature T2 (320 ° C.) to form a gas diffusion member 6 for an oxidant electrode having a two-layer structure including a coarse layer 8 and a dense layer 9. The reason why the temperature T2 is lower than the temperature T1 is that the pulp fibers have already been burned off.

The gas diffusion member 6 for the oxidant electrode was irradiated with a laser beam in the form of dots by a YAG laser from the dense layer 9 side to form a plurality of minute transmission holes 10 having a surface diameter of about 50 μm. The pitch P between the minute transmission holes 10 was set as shown in FIG. The number of minute permeation holes 10 per unit area is relatively smaller in the gas upstream area UA than that in the gas downstream area DA (750 / cm ² ). The number of minute permeation holes 10 per unit area is relatively larger in the gas downstream area DA than in the gas upstream area UA (5000 / cm ² ).

(Example 2)
The second embodiment basically has the same configuration and operational effects as the first embodiment. According to Example 2, the gas diffusion member 6 for the oxidant electrode formed in Example 1 is used, and a sewing needle having a diameter of 0.64 mm is inserted into the gas diffusion member 6 for the oxidant electrode from the dense layer 9 side. As a result, a plurality of minute transmission holes 10 were formed. The number of minute permeation holes 10 per unit area is relatively smaller (300 / cm ² ) in the gas upstream area UA2 shown in FIG. 7 than in the gas downstream area DA2. The number of fine permeation holes 10 per unit area is relatively larger in the gas downstream area DA2 than in the gas upstream area UA2 (750 / cm ² ).

The above-described gas diffusion member 6 for the oxidant electrode according to Example 1 and Example 2 was incorporated into the fuel cell model, and the performance of the fuel cell model was evaluated. A fuel cell incorporating the gas diffusion member 6 for the oxidant electrode in which the minute permeation hole 10 is not formed was used as a comparative example. According to this test, a membrane electrode assembly (MEA) having an electrode size of 12 centimeters × 12 centimeters was fabricated for fuel cell performance evaluation. As the gas distribution plate 7 for the oxidant electrode and the gas distribution plate 4 for the fuel electrode, a carbon fired product having a straight gas passage was used. The obtained IV characteristics are shown in FIG. The vertical axis in FIG. 11 indicates the relative value of the voltage, and the horizontal axis indicates the relative value of the current density. As shown in FIG. 11, Examples 1 and 2 had better power generation performance than the comparative example.
(Test example)
Based on the conditions shown in Table 1, a test piece having a coarse layer 8 (thickness 260 μm) and a dense layer 9 (thickness 40 μm) and having a minute transmission hole 10 formed in the dense layer 9 by a laser beam is used. The change of the water contact angle in was tested. In this case, an aqueous solution containing 20% by weight of ethanol was used. This is because with water alone, the contact angle is too large and no difference is produced.
In general, when the contact angle of water exceeds 90 degrees, the water repellency is assumed. The test piece T is one in which the minute transmission hole 10 is not formed. The test piece V is one in which a minute transmission hole 10 is formed by inserting a needle. Test piece 2-1, test piece 2-2, test piece 2-3, test piece 4-1, test piece 4-2, test piece 4-3, and test piece 4-4 are each formed with a laser beam and a small transmission hole Is formed.

  The test results are shown in FIG. As shown in FIG. 12, according to the test piece T in which the minute permeation hole 10 was not formed, the contact angle was as large as 136 degrees, indicating a large water repellency. This is because the dense layer 9 has a water repellent material as a main component. Even in the test piece V in which the minute transmission hole 10 was formed by inserting the needle, the contact angle was as large as 134 to 136 degrees, indicating a large water repellency. On the other hand, a test piece 2-1, a test piece 2-2, a test piece 2-3, a test piece 4-1, a test piece 4-2, a test piece 4-3, in which a minute transmission hole 10 is formed by a laser beam. According to the test piece 4-4, compared with the test piece T in which the micro permeation | transmission hole 10 is not formed, the contact angle was falling and the water repellency was falling. In particular, according to the test piece 2-1, the test piece 2-2, and the test piece 2-3, the hole diameter of the minute transmission hole 10 was increased to 100 μm or more, and the contact angle was small. Especially, according to the test piece 2-1 and the test piece 2-2, the hole diameter of the micro permeation | transmission hole 10 was as large as 110 micrometers or more, the contact angle was 90 degrees or less, and the hydrophilic property was shown. The higher the hydrophilicity, the higher the capillary pressure of the micro permeation hole 10, and the water discharging ability through the micro permeation hole 10 can be enhanced.

  FIG. 13 shows the relationship between the surface hole diameter of the minute permeation hole 10 and the contact angle of water in the dense layer 9. As shown in FIG. 13, when the laser beam intensity is increased to increase the surface hole diameter of the minute transmission hole 10, the water contact angle in the dense layer 9 tends to be relatively small, that is, the hydrophilicity is increased. A trend was obtained.

Moreover, the test piece which formed the micro permeation | transmission hole 10 in the dense layer 9 by insertion of the needle | hook was tested, and the relationship between the hole number of the permeation | transmission hole 10 per unit area and the air permeability of a normal line direction was tested. In this case, 132 sewing needles having a diameter of 0.64 mm were bundled and pressed against the dense layer 9 of the test piece with a finger to form a hole. The hole diameter was 0.14 mm. The test results are shown in FIG. The vertical axis in FIG. 14 indicates the normal air permeability, and the horizontal axis indicates the number of holes per unit area. As shown in FIG. 14, a normal air permeability As the number of holes is increased tendency to increase is obtained.

  The test results obtained by the inventor are summarized as shown in FIGS. As shown in FIGS. 15A and 15B, the gas permeability and drainage speed increase as the laser output increases. As shown in FIGS. 15C and 15D, when the number of minute permeation holes per unit area increases, the gas permeability and drainage speed increase.

  If the method of forming the minute transmission holes 10 in the dense layer 9 by irradiation with a laser beam or insertion of a needle-like member as described above is adopted, the holes of the minute transmission holes 10 per unit area as shown in FIG. The advantage that the number can be changed according to the part of the gas diffusion member 6 is obtained. Therefore, if the number of minute permeation holes 10 per unit area is locally adjusted in a portion of the gas diffusion member 6 where water is likely to accumulate, the water discharge performance and the active material supply performance are locally adjusted. Thus, there is an advantage that the power generation performance of the fuel cell can be improved.

  Depending on the case, the advantage that the depth of the micro permeation | transmission hole 10 can be locally changed according to the site | part of the gas diffusion member 6 is acquired. Therefore, if the depth of the micro permeation hole 10 is locally adjusted so that it is deeper than other portions in the portion where the water easily collects in the gas diffusion member 6, the water discharge property and the active material supply property. Can be locally adjusted, and there is an advantage that the power generation performance of the fuel cell can be improved.

(Other)
According to the above-described embodiments and examples, the minute permeation hole 10 is formed in the dense layer 9 of the gas diffusion member 6 for the oxidant electrode. However, the present invention is not limited thereto, and the gas diffusion member 3 for the fuel electrode is provided. A multi-layer structure of a rough layer and a dense layer may be used, and the minute transmission holes 10 may be formed in the dense layer. In addition, the present invention is not limited to the embodiments and examples described above and shown in the drawings, and can be implemented with appropriate modifications as necessary.

(Appendix)
The following technical idea can also be grasped from the above description.
(Additional Item 1) One side in the thickness direction is opposed to the catalyst layer, the other side in the thickness direction is opposed to the gas distribution plate, and the gas distribution plate has gas permeability and conductivity to send gas from the gas distribution plate to the catalyst layer. In a gas diffusion member for a fuel cell,
A plurality of fine permeation holes are formed so as to face the catalyst layer, and the peripheral edge portion of the micro permeation holes is relatively higher in hydrophilicity than a portion where no micro permeation holes are formed. Gas diffusion member. Since the peripheral edge of the micro permeation hole has a relatively high hydrophilicity, it is advantageous for discharging excess water through the micro permeation hole. Of the gas diffusion member for the oxidizer electrode, the portion where the micro-permeation holes are not formed has a relatively high water repellency. It is advantageous for suppressing clogging.
(Additional Item 2) In each claim, the depth of the minute permeation hole is set deeper in the gas downstream region than in the gas upstream region. It is possible to improve water discharge performance and active material supply performance in the downstream region.
(Additional Item 3) One side in the thickness direction is opposed to the catalyst layer, the other side in the thickness direction is opposed to the gas distribution plate, and the gas distribution plate has gas permeability and conductivity to send gas from the gas distribution plate to the catalyst layer. The gas diffusion member has a multilayer structure having a coarse layer facing the gas flow plate and having a relatively low density, and a dense layer facing the catalyst layer and having a density relatively higher than the coarse layer. A gas diffusion member characterized in that a minute permeation hole is formed in the dense layer at least in a gas downstream region.

  The present invention can be applied to vehicle fuel cells, stationary fuel cells, portable fuel cells, and the like.

1 is a cross-sectional view schematically showing a solid polymer fuel cell. It is sectional drawing which shows typically the gas diffusion member vicinity which formed the micro permeation | transmission hole with the laser beam. It is a block diagram which shows typically the gas channel of a gas distribution plate, and the distribution form of the micro permeation | transmission hole formed with a laser beam in the gas diffusion member facing a gas channel. FIG. 6 is a cross-sectional view schematically showing the vicinity of a gas diffusion member in which a minute transmission hole is formed by a laser beam according to the second embodiment. FIG. 6 is a cross-sectional view schematically showing the vicinity of a gas diffusion member in which a minute transmission hole is formed by a laser beam according to the third embodiment. It is sectional drawing which shows typically the form which inserts a needle-like member in the dense layer of a gas diffusion member. It is a block diagram which shows typically the gas channel of a gas distribution plate, and the distribution form of the micro permeation | transmission hole formed in a gas diffusion member facing a gas channel with a needle-shaped member. It is sectional drawing which concerns on Embodiment 4 and shows typically the gas diffusion member vicinity which formed the micro permeation | transmission hole by insertion of the acicular member. FIG. 10 is a cross-sectional view schematically showing the vicinity of a gas diffusion member in which minute permeation holes are formed from a dense layer to a rough layer according to the fifth embodiment. FIG. 10 is a configuration diagram schematically illustrating a gas passage of a gas flow distribution plate and a distribution form of minute transmission holes formed in a gas diffusion member facing the gas passage according to the sixth embodiment. It is a graph which shows the relationship between the current density and voltage in the model of a fuel cell. It is a graph which shows the change of the contact angle in each test piece. It is a graph which shows the relationship between the surface hole diameter of a micro permeation | transmission hole, and a contact angle. It is a graph which shows the relationship between the number of the micro permeation | transmission holes per unit area, and the normal air permeability of a gas diffusion member. It is a graph which shows a test result typically. It is a block diagram which shows the form which adjusted the number of the micro permeation | transmission holes per unit area according to the site | part of a gas diffusion member.

Explanation of symbols

  In the figure, 1 is an electrolyte membrane, 2 is a catalyst layer, 3 is a gas diffusion member, 4 is a gas distribution plate, 5 is a catalyst layer, 6 is a gas diffusion member, 7 is a gas distribution plate, 8 is a coarse layer, and 9 is a dense layer. Layers 10, 10 are minute transmission holes, 20 is a laser beam, 25 is a needle-like member, and 74a and 74b are gas bending regions.

Claims (6)

In the gas diffusion member having one side in the thickness direction facing the catalyst layer, the other side in the thickness direction facing the gas distribution plate, and having gas permeability and conductivity for sending the gas in the gas distribution plate to the catalyst layer,
A multi-layer structure having a coarse layer facing the gas flow plate and having a relatively low density; and a dense layer facing the catalyst layer and having a relatively higher density than the coarse layer;
When the gas outlet side in the surface direction of the gas diffusion member is the gas downstream region,
At least in the gas downstream region, a minute transmission hole provided by irradiation with a high energy density beam or insertion of a needle-like member is formed in the dense layer ,
The gas distribution plate has a gas bending region in which a gas flow is bent, and the minute permeation hole is the dense layer in a portion of the gas diffusion member facing the gas bending region of the gas distribution plate. A gas diffusion member formed by the method described above . In Claim 1, in the part which opposes the gas curvature area | region of the said gas distribution plate, the number of the said micro permeation | permeation holes per unit area becomes larger than the gas upstream area | region or the gas straight movement area | region where gas flows straight. A gas diffusion member characterized by being set as follows. 3. The gas diffusion member according to claim 1 , wherein the depth of the minute permeation hole is set deeper in the gas downstream region than in the gas upstream region. A gas whose one side in the thickness direction is opposed to the catalyst layer, the other side in the thickness direction is opposed to the gas flow plate having a gas bending region in which the gas flow is bent, and gas from the gas flow plate is sent to the catalyst layer In the method of manufacturing a gas diffusion member having permeability and conductivity,
A sheet having a multilayer structure having a coarse layer facing the gas distribution plate and having a relatively low density and a dense layer facing the catalyst layer and having a relatively higher density than the coarse layer is formed. Sheet forming process to
By irradiating the dense layer with a high energy density beam, a plurality of minute permeation holes are formed in a portion of the gas diffusion member facing the gas bending region of the gas flow plate. method for producing a gas diffusion member which comprises a hole forming step of forming a plurality of micro through holes in at least the dense layer. A gas whose one side in the thickness direction is opposed to the catalyst layer, the other side in the thickness direction is opposed to the gas flow plate having a gas bending region in which the gas flow is bent, and gas from the gas flow plate is sent to the catalyst layer In a manufacturing method for manufacturing a gas diffusion member having permeability and conductivity,
A sheet having a multilayer structure having a coarse layer facing the gas distribution plate and having a relatively low density and a dense layer facing the catalyst layer and having a relatively higher density than the coarse layer is formed. Sheet forming process to
By inserting the needle-like member into the dense layer, a plurality of minute permeation holes are formed at least on the dense sheet of the gas diffusion member so as to be formed in a portion of the gas diffusion member facing the gas bending region. And a hole forming step of forming a plurality of micro-permeable holes in the layer. An electrolyte membrane based on an electrolyte; a fuel electrode catalyst layer disposed on one side in a thickness direction of the electrolyte membrane; and a fuel electrode disposed on the opposite side of the fuel electrode catalyst layer to the electrolyte membrane Gas diffusion member for fuel electrode, gas distribution plate for fuel electrode arranged on the opposite side of the electrolyte membrane among the gas diffusion member for fuel electrode, and for the oxidant electrode arranged on the other side in the thickness direction of the electrolyte membrane A catalyst layer, a gas diffusion member for the oxidant electrode disposed on the side opposite to the electrolyte membrane in the catalyst layer for the oxidant electrode, and a gas diffusion member disposed on the opposite side of the gas diffusion member for the oxidant electrode In the fuel cell comprising the gas distribution plate for the oxidant electrode,
At least one of the gas diffusion member for the fuel electrode and the gas diffusion member for the oxidant electrode is formed of the gas diffusion member according to any one of claims 1 to 5. Fuel cell.

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