JP2007234524A - Fuel cell, gas diffusion layer for fuel cell and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas diffusion layer in which optimal improvement in gas permeability and a water discharging property is obtained. <P>SOLUTION: The gas diffusion layer for a fuel cell is composed of catalyst layers 3 with each pole arranged on both sides of an electrolyte membrane 2 and also each of gas diffusion layers 4 arranged and pinched by separators 5 on the both sides and is used as one of gas diffusion layers for the fuel cell, and a plurality of fiber members 10 more hydrophilic than a base material of the gas diffusion layer 4 penetrate and are embedded in the above base material in a thickness direction of the base material. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell, a gas diffusion layer for a fuel cell, and a method for producing the same, and more particularly to a fuel cell suitable for improving gas permeability and water discharge performance, a gas diffusion layer for a fuel cell, and a method for producing the same. .

  Conventionally, gas diffusion layers in which a hydrophilic material and / or a water-repellent material are included in a material constituting the gas diffusion layer in order to improve gas permeability and water discharge properties have been proposed (see Patent Documents 1 and 2). ).

  In Patent Document 1, the gas diffusion layer of the fuel cell electrode is woven so as to intersect each other with the first fiber bundle made of hydrophilic carbon fiber as the warp and the second fiber bundle made of water-repellent carbon fiber as the weft. Made of woven fabric, which allows the water vapor and water generated in the electrode catalyst layer to move quickly out of the container of the fuel cell and provides sufficient diffusion capacity for the fuel gas and oxygen-containing gas. Intended.

In Patent Document 2, gas permeability is obtained by forming a gas diffusion layer from a mixture of a reticulated sheet having heat resistance and acid resistance, and a conductive powder and a water-repellent filler filling the voids of the reticulated sheet. It is intended to be excellent in water repellency and the like and excellent in mechanical strength.
JP 2002-15747 A JP 2002-170572 A

  However, in each of the above conventional examples, since the hydrophilic material and / or the water repellent material is woven or mixed, these are not necessarily arranged in the thickness direction of the gas diffusion layer, There was a problem that the movement of gas and water between the front surface side and the back surface side was not sufficient.

  Therefore, the present invention has been made in view of the above problems, and an object thereof is to provide a fuel cell, a gas diffusion layer for a fuel cell, and a method for manufacturing the same suitable for improving gas permeability and water discharge.

  The present invention provides a fuel for use in at least one of the gas diffusion layers of a fuel cell in which catalyst layers of the respective electrodes are arranged on both surfaces of an electrolyte membrane, and each gas diffusion layer is interposed and sandwiched by separators from both surfaces. The battery gas diffusion layer is configured to include a plurality of fibrous members that are more hydrophilic than the base material of the gas diffusion layer so as to penetrate in the thickness direction of the base material.

  Therefore, in the present invention, the fuel cell gas diffusion layer is configured to include a plurality of fibrous members that are more hydrophilic than the base material of the gas diffusion layer and penetrate in the thickness direction of the base material. The liquid droplets in the diffusion layer can be collected to promote the discharge of water from the gas diffusion layer, while the liquid droplets in the gas diffusion layer can be collected, thereby ensuring a gas diffusion path. Gas permeability and water discharge performance can be improved.

  Hereinafter, an embodiment of a fuel cell, a gas diffusion layer for a fuel cell, and a manufacturing method thereof according to the present invention will be described with reference to the drawings. 1 is a schematic view of a fuel cell to which a first embodiment of a gas diffusion layer for a fuel cell to which the present invention is applied, FIG. 2 is a sectional view showing a second embodiment of the gas diffusion layer for a fuel cell, FIG. These are top views which show the 3rd Example of the gas diffusion layer for fuel cells.

  As shown in FIG. 1, the fuel cell 1 includes an electrolyte membrane electrode stack by disposing the electrode catalyst layers 3 on both sides of the reaction region of the electrolyte membrane 2, and sandwiches the electrolyte membrane electrode stack. The gas diffusion layers 4 of the respective electrodes are arranged as described above, while a gasket (not shown) is arranged in the peripheral region surrounding the reaction region of the electrolyte membrane 2 and these are sandwiched by the separator 5.

  The fuel cells 1 are stacked in series, end plates (not shown) are arranged at both ends in the stacking direction, and the fuel cells 1 are stacked by fixing by applying a load in the stacking direction with a tie rod (not shown). A predetermined tightening load is applied to the fuel cell stack. A fuel cell stack to be mounted on a fuel cell vehicle is configured by stacking, for example, 300 to 400 fuel cell cells 1 as a unit unit in series.

  Each of the separators 5 is provided on the side in contact with the gas diffusion layer 4 by introducing, for example, hydrogen as an anode gas (or air as a cathode gas, for example) from the inlet manifold and supplying the gas diffusion layer 4 to the gas diffusion layer 4. A gas flow path 6 is formed for discharging the gas not used for the reaction to the outlet manifold.

  The back side of the separator 5 is adjacent to the type shown on the left side in the figure in which a flow path 7 is formed in which the fluid for adjusting the stack temperature flows from the inlet manifold toward the outlet manifold, although not shown. As described on the right side of the figure, the gas flow path for supplying and discharging the anode gas or cathode gas of the adjacent fuel battery cell that is also used as a battery cell separator is formed. Any one of the types formed on a plane is selected and laminated as necessary.

  The gas diffusion layer 4 is generally a porous material having innumerable fine pores of 50 to 500 [μm], for example, carbon paper made of carbon fiber, carbon cloth made of carbon fiber, and carbon. It is comprised by the nonwoven fabric etc. and also the paper-like porous sheet etc. which were comprised with the metal. This gas diffusion layer 4 is one of the roles required to have a function of diffusing and supplying the supply gas from the separator 5 to the catalyst layer 3 and a function of discharging water generated by a chemical reaction. Therefore, if the function is lowered depending on the power generation conditions, the gas diffusibility is lowered as the drainage performance is lowered, and the power generation performance is lowered.

  In the first example of the gas diffusion layer 4 in the present embodiment, a plurality of hydrophilic fiber members 10 are arranged to penetrate in the thickness direction in the gas diffusion layer 4. The fiber member 10 is a fibrous member whose material itself is more hydrophilic than the base material of the gas diffusion layer 4, for example, the fiber member 10 is a hydrophilic resin or a surface having a hydrophilic resin as a main component on the surface of the base material. Metal that has been treated (hydrophilic treatment), metal whose surface layer has been oxidized, metal that has been surface-treated with a hydrophilic resin as a main component, and carbon whose surface layer has been hydrophilized Alternatively, carbon or carbon fiber having a hydrophilic coating can be used.

  In this way, by disposing the plurality of fiber members 10 having hydrophilicity through the thickness direction in the gas diffusion layer 4, the droplets in the diffusion layer 4 are collected and water from the gas diffusion layer 4 is collected. The discharge of gas can be promoted, while the liquid droplets in the gas diffusion layer 4 are collected, so that a gas diffusion path can be secured as a result. In other words, the fibrous member 10 is disposed in the thickness direction inside the gas diffusion layer 4 so that the fibrous member 10 is more hydrophilic than the base material of the gas diffusion layer 4. The movement in the thickness direction within 4 can be improved and controlled.

  Since the fiber member 10 is subjected to a hydrophilic resin or a surface treatment mainly including a hydrophilic resin on the surface of the base material, the hydrophilic member does not necessarily need to have electrical conductivity. It can be carried out with a fibrous member whose surface is hydrophilized. As long as at least the hydrophilicity of the gas diffusion layer 4 is maintained, droplets in the diffusion layer 4 can be collected, and as a result, a gas diffusion path can be secured.

  The fiber member 10 may be made of metal. In this case, the surface layer is oxidized or a surface treatment mainly including a hydrophilic resin is performed. Since it has corrosion resistance under the fuel cell operating environment and the surface is coated with an oxidized or hydrophilic resin, the droplets in the diffusion layer 4 can be collected, resulting in a gas diffusion path. Can be secured. Furthermore, since the fiber member 10 has electrical continuity, the electrical resistance in the thickness direction of the diffusion layer 4 can also be lowered.

  The fiber member 10 may be formed of carbon. In this case, the surface layer is hydrophilized or is coated with a hydrophilic coating. In particular, when carbon fiber or the like is used, electrical continuity can be achieved. In this case, since the base material constituting the gas diffusion layer 4 is also carbon, it is possible to achieve hydrophilicity by oxidation of the surface layer or modification with a hydrophilic functional group, or the effect can be enhanced with an entire coat or a partial coat of the hydrophilic resin. it can.

  In addition, although it is considered that the corrosive environment in the cell varies depending on the operating conditions of the fuel cell, when the amount of water in the cell is small and power generation is often performed under relatively high acidity, the fiber The member 10 may be formed of glass or ceramics.

  By forming minute grooves in the surface layer of each of the fibrous members 10 described above so as to be continuous in the longitudinal direction of the fibers, the mobility of water can be further improved by capillary action.

  The fiber member 10 is arranged so that one end thereof is located at a position where it stays inside the gas diffusion layer 4 without being exposed from one surface of the gas diffusion layer 4 in contact with the catalyst layer 3. When the catalyst layer 3 and the electrolyte membrane 2 are stacked, the electrolyte membrane 2 is not damaged by the end portion of the fiber member 10.

  The pull-in dimension from the surface of the gas diffusion layer 4 at the one end is such that when the fuel cell 1 is stacked as a fuel cell stack and a compressive load is applied as the stack, the gas diffusion layer 4 is compressed and deformed in the stacking direction. In anticipation of this, even when the gas diffusion layer 4 is deformed when a load slightly exceeding the compression load is applied, the one end of the fiber member 10 does not protrude from one surface of the gas diffusion layer 4. Is set. These considerations do not need to be so much considered for the flexible and easily deformable fiber member 10, but are particularly necessary when the material of the fiber member 10 is a hard fiber.

  The other end portion of the fiber member 10 is exposed on the other surface of the gas diffusion layer 4, and particularly preferably, is exposed on the surface of the separator 5 facing the gas flow path 6 and actively protrudes. This is because the droplets can be promoted to move to the gas flow path 6 of the separator 5 along the hydrophilic fiber member 10. Particularly, the liquid gathered along the hydrophilic fiber member 10 by disposing the fiber member 10 so as to be inclined perpendicularly or downstream with respect to the gas flow direction of the gas flow path 6. The droplets can be easily evaporated and scattered according to the gas flow.

  The arrangement density of the fiber members 10 to the gas diffusion layer 4 may be arranged at an equal density with reference to the range in which the fiber members 10 can collect droplets in the gas diffusion layer 4. It is desirable to arrange with a density distribution according to the distribution of the amount of droplets generated in the operating state. For example, the arrangement density of the fiber members 10 to the gas diffusion layer 4 arranged on the cathode side is made higher than the arrangement density of the fiber members 10 arranged on the gas diffusion layer 4 arranged on the anode side. The drainage performance of the electrochemically generated water is increased, and the power generation performance degradation due to water clogging in the gas diffusion layer 4 is suppressed.

  Also, in the same gas diffusion layer 4, considering the droplet distribution, the more downstream the gas flow direction (in particular, the cathode side), the smaller the amount of droplets for humidified water and reaction product water. Therefore, the drainage can be improved by increasing the arrangement density of the fiber members 10 accordingly.

  Further, even in the separator 5 facing the gas diffusion layer 4, corrosion can be suppressed even if the material is made of metal. This suppresses the formation of minute highly acidic droplet paths in the diffusion layer 4 linking the electrolyte membrane 2 and the separator 5 that may cause corrosion of the metal separator 5, that is, The droplet path is less likely to occur.

  In the second example of the gas diffusion layer in the present embodiment, as shown in FIG. 2, a configuration in which a plurality of hydrophilic fiber members 10 are disposed obliquely through the gas diffusion layer 4 in the thickness direction. It is said. The fiber member 10 in this embodiment is disposed so as to be inclined from the region overlapping the ribs 8 arranged between the adjacent flow channels 6 of the separator 5 toward the region opened to the flow channel 6.

  This is because the droplets generated in the region overlapping the ribs 8 where the droplets in the gas diffusion layer 4 are difficult to be discharged are inclined, and the droplets opened to the channel 6 are relatively easily discharged by the fiber member 10. The liquid is positively moved to the region and discharged to the flow path 6, whereby the liquid droplets 10 can be promoted to move to the separator flow path 6 along the hydrophilic fiber member 10. The droplet discharge performance can be improved.

  The fiber member 10 is arranged so that the end of the fiber member 10 positively protrudes into the gas flow path 6 of the separator 5, so that the droplets flow into the gas flow path 6 of the separator 5 along the fiber member 10 exhibiting hydrophilicity. It can promote moving. Then, flooding can be prevented by water movement from the rib 8 of the separator 5 to the flow path 6 of the separator 5.

  In the third example of the gas diffusion layer in the present embodiment, as shown in FIG. 3, a plurality of hydrophilic layers that are arranged obliquely through the gas diffusion layer 4 shown in the second example in the thickness direction. The fiber member 10 is further arranged so as to be inclined vertically or downstream with respect to the gas flow direction. As a result, the droplets collected along the hydrophilic fiber member 10 can be easily evaporated and scattered according to the gas flow in the gas flow path 6 (see the arrow in the figure). That is, by providing an inclination with respect to the gas flow direction, water movement on the fiber member 10 can be effectively performed using the gas flow.

  Further, in this embodiment, the arrangement density of the fiber members 10 in the surface of the gas diffusion layer 4 is arranged so as to be higher in the downstream with respect to the gas flow direction in consideration of the droplet distribution in the cell 1. The number distribution is changing. As the gas flow becomes more downstream, liquid droplets are more likely to stay in the gas diffusion layer 4, so that the drainage can be improved by increasing the number of downstream arrangements according to the water distribution. In particular, since the amount of droplets is increased due to the humidified water and the reaction product water in the downstream area on the cathode side, the drainage performance is improved by increasing the number of fiber members 10 arranged accordingly.

  In the fuel cell gas diffusion layer of the present embodiment, the following effects can be obtained.

  (A) At least one of the gas diffusion layers 4 of the fuel cell in which the catalyst layers 3 of the respective electrodes are disposed on both surfaces of the electrolyte membrane 2 and further sandwiched by separators 5 from both surfaces with the gas diffusion layers 4 interposed therebetween. The fuel cell gas diffusion layer 4 used for the two is configured to include a plurality of fibrous members 10 that are more hydrophilic than the base material of the gas diffusion layer 4 so as to penetrate in the thickness direction of the base material. The liquid droplets in the diffusion layer 4 can be collected and the discharge of water from the gas diffusion layer 4 can be promoted, while the liquid droplets in the gas diffusion layer 4 are collected, thereby securing a gas diffusion path. Gas permeability and water discharge performance can be improved.

  (A) By forming the fibrous member 10 with the resin member 10 having a hydrophilic resin or a surface treatment mainly composed of a hydrophilic resin applied to the surface of the substrate, the hydrophilic member is formed of the gas diffusion layer 4. It is not always necessary to have electrical continuity, which is one requirement, and it can be implemented with a hydrophilic resin or a resin member whose surface has been subjected to a hydrophilic treatment. If at least hydrophilicity is maintained from the gas diffusion layer 4, droplets in the diffusion layer 4 can be collected, and as a result, a gas diffusion path can be secured.

  (C) By forming the fibrous member 10 with a metal whose surface layer is oxidized or surface-treated with a hydrophilic resin as a main component, it has corrosion resistance even in a fuel cell operating environment. In addition, since the surface is coated with an oxidized or hydrophilic resin, the effect (A) can be exhibited. Furthermore, since the fibrous member 10 has electrical continuity, the electrical resistance in the thickness direction of the gas diffusion layer 4 can also be lowered.

  (D) The electrical conduction of the gas diffusion layer 4 is formed by forming the fibrous member 10 with carbon whose surface layer has been hydrophilically modified or coated with hydrophilic coating, such as carbon fiber. Can be improved. In addition, since the base material which comprises the gas diffusion layer 4 is also carbon, it can improve hydrophilicity by oxidation of a surface layer or modification by a hydrophilic functional group, or the effect can be improved with the entire hydrophilic resin or a partial coat.

  (E) If the surface layer of the fibrous member 10 is provided with a micro-groove in the longitudinal direction of the fiber, the mobility of water can be further improved by capillary action.

  (F) The arrangement density of incorporating the fibrous member 10 in the gas diffusion layer 4 arranged on the cathode side is higher than the arrangement density of incorporating the fibrous member 10 in the gas diffusion layer 4 arranged on the anode side of the fuel cell 1. As a result, electrochemically generated water is generated on the cathode side regardless of the upstream and downstream of the gas flow, so that the power generation performance is reduced due to water clogging in the gas diffusion layer 4 by increasing the arrangement density from the anode side to the cathode side. Can be suppressed.

  (G) Even if the separator 5 facing the gas diffusion layer 4 is made of metal, a minute highly acidic liquid droplet in which the electrolyte membrane 2 and the separator 5 are connected, which may cause corrosion of the metal separator 5. Is prevented from being formed in the diffusion layer 4, that is, the droplet path is less likely to occur, and corrosion of the metal separator 5 can be suppressed.

  (H) The fibrous member 10 is in contact with the catalyst layer 3 in the region overlapping the ribs 8 arranged between the gas flow paths 6 formed in the separator 5, and the separator 5 in the region overlapping the gas flow channel 6 from one surface side. By being inclined toward the other surface in contact with the surface, flooding can be prevented by water movement from the rib 8 of the separator 5 to the flow path 6 of the separator 5.

  (E) The end of the fibrous member 10 on the separator 5 side protrudes from the other surface of the gas diffusion layer 4 on the separator 5 side and is exposed to the gas flow path, thereby being along the hydrophilic fiber member 10. The collected liquid droplets can be easily evaporated and scattered by the gas in the gas flow path 6.

  (E) When the fibrous member 10 is disposed so that the end portion on the separator 5 side is inclined toward the downstream side of the gas flow path 6 of the separator 5, the water on the fibrous member 10 is utilized using the dynamic pressure due to the gas flow. Movement can be performed effectively.

  (Sa) The fibrous member 10 is arranged so that the arrangement density thereof becomes higher in the gas diffusion layer 4 in the downstream side with respect to the gas flow direction flowing through the gas flow path 6 of the separator 5 in the plane of the gas diffusion layer 4. Since the liquid stays in the gas diffusion layer 4 more easily in the downstream of the gas flow, the drainage can be improved by increasing the number of arrangement on the downstream side.

  A method for manufacturing the fuel cell separator having the above-described configuration will be described below with reference to FIGS. Here, an outline of the manufacturing method will be described based on FIGS. 4 to 8, and a specific manufacturing method will be described based on FIGS. 9 to 13.

  First, the outline of the manufacturing method is as shown in FIG. The tip is inserted through the gas diffusion layer 4 and protrudes from the other surface 12B (the lower surface in the figure) that is in contact with the separator 5. When penetrating the gas diffusion layer 4, the tip of the fiber member 10 is fixed to a needle or the like having good penetrability to the gas diffusion layer 4 so as not to affect the diffusion layer 4 around the penetration portion as much as possible. It is desirable to penetrate with a needle.

  Next, as shown in FIG. 5, a cut end portion 13 is formed by cutting a portion exposed from one surface side of the fiber member 10 that has been penetrated. Then, as shown in FIG. 6, the cut end 13 is drawn into the gas diffusion layer 4 by pulling the tip of the fiber member 10 forward (downward in the figure). Further, as shown in FIG. 7, the leading end side of the penetrated fiber member 10 is cut at a cutting portion 14 protruding by a predetermined length from the other surface (the lower surface in the drawing) of the gas diffusion layer 4. Through the above process, a large number of fiber members 10 can be manufactured by arranging them in the diffusion layer 4 based on a predetermined distribution ratio.

  Since the latter cut end portion 14 protrudes from the surface of the diffusion layer 4 or from the diffusion layer 4, when the fuel cell 1 is assembled, the cut end portion 13 cut first is diffused as shown in FIG. The catalyst layer 3 and the electrolyte membrane 2 are disposed on the side of the one surface 12A drawn into the layer 4. That is, if the fiber end portion 13 protrudes from the diffusion layer, the cut end portion 13 of the fiber member 10 may pierce the electrolyte membrane 2 during assembly as the fuel cell 1, which may lead to damage of the electrolyte membrane 2. It is. This depends on the material of the fiber, but the harder the fiber, the higher the need for the arrangement shown in FIG.

  In a fuel cell stack, in most cases, a plurality of unit unit cells (fuel cell 1), which are constituent members, are stacked and used after being compressed. During this compression, the porous gas diffusion layer 4 is compressed by the load. There is a possibility that the cut end portion 13 of the fiber member 10 protrudes toward the electrolyte membrane 2 from one surface of the gas diffusion layer 4 compressed in a state where the fiber member 10 is disposed.

  Therefore, before assembly after cutting both ends of the fiber member 10, as shown in FIG. 8, pre-compression is performed so that the cut end portion 13 of the fiber member 10 does not protrude above the surface of the one surface 12A. Can be. That is, in FIG. 8, the plate 30 is disposed on both surfaces of the gas diffusion layer 4, and the gas diffusion layer 4 is compressed by the plate 30 by applying a load higher than the load formed as the stack, thereby cutting the fiber member 10. The end 13 is held within the one surface 12A.

  In this case, the lower plate 30 has a hole as shown in the drawing so that the lower end portion 14 in the figure from which the fiber member 10 protrudes is not pushed into the gas diffusion layer 4 by the plate 30. It is desirable to be provided. The holes need to be provided in the corresponding locations for the number of fiber members 10 to be incorporated in the gas diffusion layer 4, and the lower plate 30 is preferably formed in a mesh structure.

  The pre-compression of the gas diffusion layer 4 is performed on the portion where the fiber member 10 is arranged in the diffusion layer 4 or when the arrangement of all the fiber members 10 in the diffusion layer 4 is completed. It can also be performed on all four. Further, after passing the fibrous member 10 from the one surface 12A of the gas diffusion layer 4 to the back surface 12B, the fiber member 10 is cut at one surface portion 12A of the gas diffusion layer 4, and the other surface of the gas diffusion layer 4 is cut. The end portion 13 of the cut fiber member 10 is moved into the gas diffusion layer 4 by pulling the side fibers, and then the gas diffusion layer 4 is compressed by applying a certain load, and then the other surface 12B side You may make it cut | disconnect the fiber member 10 which protrudes from. That is, before cutting the other, pressurization is performed at a pressure equal to or higher than the surface pressure applied to the fuel cell stack, so that the cut end portion 13 can be prevented from coming out from one surface of the diffusion layer 4 when the actual cell stack is assembled. This pre-compression may be performed by all the gas diffusion layers 4 necessary for stack assembly or batch processing for every certain quantity.

  9 is a specific assembly process diagram of the fuel cell separator, FIG. 10 is a schematic view of an assembly apparatus including a work table, FIG. 11 is a schematic view showing XY coordinates of the gas diffusion layer, and FIG. FIG. 13 is a characteristic diagram showing a load-thickness relationship characteristic of a gas diffusion layer, and FIG. 13 is a schematic diagram of a fiber member arrangement method and a compression method in a gas diffusion layer including a table.

  As shown in FIG. 10, innumerable through holes 32 through which the fiber member 10 passes are arranged on the work table 31 (in the illustrated example, only one through hole 32 is shown). The infinite number of through holes 32 may be formed by forming the work table 31 with a mesh member. Further, above the work table 31, for example, a laser beam emitting device 33 for cutting the fiber member 10 is disposed slightly above the upper surface 12A of the gas diffusion layer 4 to be arranged. A fiber member feeding means 34 for feeding the fiber member 10 into the gas diffusion layer 4 is disposed.

  Further, as shown in FIG. 12, a press means 35 for compressing the gas diffusion layer 4 is disposed above the work table 31. Below the work table 31, a holding means 36 that holds the tip of the fiber member 10 that passes through the gas diffusion layer 4 and passes through the through hole 32 is disposed. For example, a laser beam emitting device 37 is disposed.

  In the process diagram shown in FIG. 9, first, in step 1, the gas diffusion layer 4 is positioned and arranged on the work table 31.

  In step 2, as shown in FIG. 11, on the XY coordinates of the gas diffusion layer 4, the coordinate position where the fiber members 10 are arranged is set for each fiber member 10. This step 2 can be preset.

  In step 3, the fiber member 10 is pushed from the upper surface 12 </ b> A of the gas diffusion layer 4 by the fiber member feeding means 34 to a preset coordinate position of the gas diffusion layer 4, penetrates the gas diffusion layer 4, and It passes through the through hole 32 and protrudes downward from the work table 31. In this case, although the fiber member 10 is arranged perpendicularly to the work table 31 in the figure, the fiber member 10 may be penetrated obliquely with respect to the work table 31, as shown in FIG. 2 or FIG. it can.

  In step 4, the leading end portion of the fiber member 10 that penetrates and protrudes downward from the work table 31 is held by the holding means 36. When holding the fiber member 10 so as to be pulled downward by the holding means 36 during the holding, the fiber member 10 moves downward in the work table 31 when the fiber member 10 is cut in step 5 which is a subsequent process. Therefore, it is important that the fiber member 10 is not tensioned or that the fiber is not loosened by pulling from the side opposite to the holding means 36 (above the work table 31).

  In step 5, the part connected to the upper surface side of the gas diffusion layer 4 of the fiber member 10 is cut. The cutting method can also be performed by moving the cutter along the surface layer of the diffusion layer 4 and cutting by irradiating the laser beam from the laser beam emitting device 33. When cutting the fiber member 10, it is preferable that the cut surface be parallel to the surface 12 </ b> A of the diffusion layer 4 regardless of the insertion angle of the fiber member 10 into the gas diffusion layer 4. If the cut surface is not parallel to the surface of the diffusion layer 4, the electrolyte membrane 2 may be damaged by the cut edge 13 of the fiber member 10.

  In step 6, the fiber member 10 penetrated by the holding means 36 is pulled downward, and the cut portion 13 cut by the laser is drawn directly under the surface 12 A of the gas diffusion layer 4. As shown in FIG. 13, it is preferable to set the pulling length L with reference to the collapse allowance value of the diffusion layer 4 that is collapsed when the diffusion layer 4 is compressed in advance.

  A plurality of fiber members 10 can be disposed on the surface of the diffusion layer 4 by continuously executing the above-described Step 3 to Step 6 while changing the input position of the fiber member 10. This loading position is executed by positioning the fiber member feeding means 34 each time in accordance with the XY coordinate position set in step 2. Moreover, although the description has been made so that one fiber member 10 is arranged on the work table 31, in practice, the arrangement of a plurality of fiber members 10 may be executed in parallel. For this reason, the cutting | disconnection by the laser beam emission apparatus 33 can raise efficiency more, if the several fiber member 10 is implemented simultaneously. When the arrangement of all the fiber members 10 on the diffusion layer 4 is completed, the process proceeds to Step 7.

  In step 7, the press means 35 located above the work table 31 is lowered to compress the entire gas diffusion layer 4 with a predetermined load set in advance. By compressing, the fiber member 10 penetrating the gas diffusion layer 4 is extruded below the gas diffusion layer 4 by the compression allowance. In this state, the laser beam emitting device 37 disposed below the gas diffusion layer 4 cuts a large number of fiber members 10 projecting under the work table 31 including the amount of extrusion in step 7 with a laser.

  When the fiber member 10 is cut at a location away from the surface layer of the diffusion layer 4, the cutting comes into contact with the separator 5 in a state where the fiber member 10 is hung, so that the cutting as close to the surface layer of the diffusion layer 4 as possible is possible. desirable. For this purpose, a slit space that allows the passage of the laser beam is formed above the work table 31 or in the center of the work table 31 in the thickness direction, and the laser beam is emitted into the slit space to move downward. The protruding amount of the fiber member 10 can be reduced.

  When the brace means 35 is raised at the stage where the cutting of the fiber member 10 protruding downward is completed, the thickness dimension of the gas diffusion layer 4 returns to the uncompressed state and protrudes downward from the gas diffusion layer 4. Further, the fiber member 10 is drawn into the gas diffusion layer 4 by the amount of collapse of the gas diffusion layer 4, and the production of the gas diffusion layer 4 is completed.

  In the manufacturing method of the fuel cell gas diffusion layer of the present embodiment, the following effects can be obtained.

  (G) A method for producing the gas diffusion layer 4 of the fuel cell, in which the catalyst layers 3 of the respective electrodes are disposed on both surfaces of the electrolyte membrane 2 and further sandwiched by separators 5 from both surfaces with the gas diffusion layers 4 interposed therebetween. The fibrous member 10 having a higher hydrophilicity than the base material of the gas diffusion layer 4 is passed through the fibrous member 10 from one surface of the base material facing the catalyst layer 3 to the back surface, Since the fibrous member 10 exposed from the surface is cut so as to be embedded in the base material in a through state in the thickness direction, the fibrous member 10 is mixed when the base material of the gas diffusion layer 4 is manufactured. The fiber member 10 can be surely arranged in the thickness direction at a required place of the gas diffusion layer 4 rather than being manufactured.

  (Su) After the fibrous member 10 exposed from the one surface 12A is cut, the fibrous member 10 is drawn from the back surface side to draw the end 13 of the cut fibrous member 10 in the gas diffusion layer. 4, and the fibrous member 10 exposed on the back surface side is cut, so that the end portion 13 on the one surface 12A side that is in contact with the catalyst layer 3 can be moved into the gas diffusion layer 4. In addition, it is possible to prevent the catalyst layer 3 and the electrolyte membrane 2 from being damaged or damaged due to the end 13 of the fibrous member 10 coming out of the surface layer of the diffusion layer 4.

  (C) After the fibrous member 10 exposed from the one surface 12A is cut, the fibrous member 10 is pulled from the back side to pull the end portion 13 of the cut fibrous member 10 into the gas diffusion layer. 4, the gas diffusion layer 4 base material is compressed in the thickness direction by a preset load, and the fibrous member 10 exposed on the back surface side in the compressed state is cut, whereby the fibers on the back surface side By compressing and pressurizing the tubular member 10 before cutting, it is possible to prevent the end portion 13 of the fibrous member 10 from protruding from one surface 12A of the gas diffusion layer 4 even during assembly of the actual fuel cell stack. it can.

  (G) By making the applied load to the gas diffusion layer 4 equal to or greater than the tightening load applied during the assembly of the fuel cell stack, it is possible to prevent the electrolyte membrane 2 from being damaged during the actual assembly of the fuel cell stack.

  (T) The end portion of the first fibrous member 10 cut first by making the one surface 12A side of the gas diffusion layer 4 from which the fibrous member 10 was cut first the surface facing the catalyst layer 3 and the electrolyte membrane 2 13 moves to the inside of the gas diffusion layer 4, and can prevent the end portion 13 of the fibrous member 10 from damaging the electrolyte membrane 2.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the fuel cell which applied the 1st Example of the gas diffusion layer for fuel cells which shows one Embodiment of this invention. Sectional drawing which similarly shows 2nd Example of the gas diffusion layer for fuel cells. The top view which shows 3rd Example of the gas diffusion layer for fuel cells. Schematic which shows the arrangement | positioning method of the fibrous member to a gas diffusion layer. Schematic which shows the arrangement | positioning method of the fibrous member to the gas diffusion layer following FIG. Schematic which shows the arrangement | positioning method of the fibrous member to the gas diffusion layer following FIG. Schematic which shows the arrangement | positioning method of the fibrous member to the gas diffusion layer following FIG. Schematic which shows the arrangement | positioning method of the fibrous member to the gas diffusion layer following FIG. The specific assembly process figure of the separator for fuel cells. Schematic of an assembling apparatus including a work table. Schematic which shows the XY coordinate of a gas diffusion layer. The schematic diagram of the fiber member arrangement method and compression method to the gas diffusion layer containing a work table. The characteristic view which shows the load-thickness relation characteristic of a gas diffusion layer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Electrolyte membrane 3 Catalyst layer 4 Gas diffusion layer, diffusion layer 5 Separator 6 Gas flow path 8 Rib 10 Fiber member, fibrous member 12A One surface 13, 14 End

Claims (17)

Gas diffusion for a fuel cell used for at least one of the gas diffusion layers of a fuel cell provided with a catalyst layer of each electrode on both surfaces of the electrolyte membrane, and further sandwiched by a separator from both surfaces with a gas diffusion layer interposed therebetween Layer,
A gas diffusion layer for a fuel cell, comprising a plurality of fibrous members that are more hydrophilic than the base material of the gas diffusion layer and are embedded in the thickness direction of the base material.   2. The fuel cell gas according to claim 1, wherein the fibrous member is formed of a hydrophilic resin or a resin member whose surface is mainly treated with a hydrophilic resin. Diffusion layer.   2. The gas diffusion layer for a fuel cell according to claim 1, wherein the fibrous member is formed of a metal having a surface layer oxidized or a surface treatment mainly including a hydrophilic resin. .   2. The gas diffusion layer for a fuel cell according to claim 1, wherein the fibrous member is made of carbon whose surface layer is hydrophilically modified or coated with a hydrophilic coating. 3.   The gas diffusion layer for a fuel cell according to any one of claims 1 to 4, wherein the fibrous member includes a minute groove on a surface layer thereof in a longitudinal direction of the fiber.   2. The arrangement density incorporated in the gas diffusion layer arranged on the cathode side is higher than the arrangement density incorporated in the gas diffusion layer arranged on the anode side of the fuel cell. The gas diffusion layer for fuel cells according to claim 5.   The fibrous member is inclined from one surface side in contact with the catalyst layer in the region overlapping the ribs arranged between the gas flow paths formed in the separator toward the other surface in contact with the separator in the region overlapping the gas flow channel. The gas diffusion layer for a fuel cell according to any one of claims 1 to 6, wherein the gas diffusion layer is arranged as described above.   8. The fuel cell gas diffusion layer according to claim 7, wherein an end of the fibrous member on the separator side protrudes from the other surface of the gas diffusion layer on the separator side and is exposed to the gas flow path. 9. .   The gas diffusion for a fuel cell according to claim 7 or 8, wherein the fibrous member is disposed so that an end portion on the separator side is inclined toward a downstream side of a gas flow path of the separator. layer.   2. The fibrous member is arranged such that the arrangement density thereof becomes higher as it is downstream in the gas flow direction of the separator in the gas flow path in the plane of the gas diffusion layer. The gas diffusion layer for fuel cells according to any one of claims 9 to 9. In a fuel cell provided with a catalyst layer of each electrode on both surfaces of an electrolyte membrane, and further sandwiched by a separator from both surfaces with a gas diffusion layer interposed,
A fuel cell comprising the gas diffusion layer including a fibrous member having a hydrophilicity higher than that of the base material so as to penetrate in the thickness direction of the base material.   12. The fuel cell according to claim 11, wherein the separator facing the gas diffusion layer is made of metal. Gas diffusion for a fuel cell used for at least one of the gas diffusion layers of a fuel cell provided with a catalyst layer of each electrode on both surfaces of the electrolyte membrane, and further sandwiched by a separator from both surfaces with a gas diffusion layer interposed therebetween A method for producing a layer, comprising:
The fibrous member having a higher hydrophilicity than the base material of the gas diffusion layer is allowed to penetrate the fibrous member from one surface facing the catalyst layer of the base material to the back surface,
Cut the fibrous member exposed from one side,
A method for producing a gas diffusion layer for a fuel cell, comprising incorporating the base material in a penetrating state in a thickness direction of the base material.   After the fibrous member exposed from the one surface is cut, the fibrous member is moved from the back side to move the end of the cut fibrous member into the gas diffusion layer, and the back side The method for producing a fuel cell gas diffusion layer according to claim 13, wherein the fibrous member exposed to the substrate is cut.   The fibrous member is set in advance by moving the end of the cut fibrous member into the gas diffusion layer by pulling from the back side after the fibrous member exposed from the one surface is cut. 14. The gas diffusion layer for a fuel cell according to claim 13, wherein the gas diffusion layer base material is compressed in the thickness direction by the applied load, and the fibrous member exposed on the back surface side in the compressed state is cut. Manufacturing method.  16. The method for producing a gas diffusion layer for a fuel cell according to claim 15, wherein the load applied to the gas diffusion layer is equal to or greater than a tightening load applied when the fuel cell stack is assembled.   The production of a gas diffusion layer for a fuel cell according to any one of claims 13 to 16, wherein one side of the gas diffusion layer from which the fibrous member is first cut is a surface facing the catalyst layer and the electrolyte membrane. Method.

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