JP4448013B2 - GAS DIFFUSION LAYER FOR FUEL CELL, ITS MANUFACTURING METHOD, AND GAS DIFFUSION LAYER LAMINATE STRUCTURE FOR FUEL CELL - Google Patents

Description

The present invention is a gas diffusion layer for a fuel cell, a manufacturing method and a fuel cell gas diffusion layer laminated structure of it.

  As a gas diffusion layer for a fuel cell, a sheet formed from a carbon fiber such as carbon paper or carbon cloth as a base material is widely used. And in order to acquire the performance as a gas diffusion layer, the water repellent process for performing the electroconductive process for improving electroconductivity and water repellency to these base materials is made | formed. However, since these base materials are expensive, when used as a gas diffusion layer for a fuel cell, there is a problem that the fuel cell becomes expensive and hinders practical use.

As a means for solving this problem, as disclosed in Patent Document 1, a slurry that is a liquid material mainly composed of carbon fiber and pulp is formed, and solids contained in the slurry are deposited. The sheet is then molded, and then the sheet is impregnated with a polymer material (PTFE or the like) having water repellency, and then the sheet is heated and held, whereby the pulp contained in the sheet disappears and pulp is removed. In recent years, a method for forming a porous carbon sheet by using traces as pores has been proposed. Since the carbon sheet is bonded to the carbon fiber by a polymer material having water repellency (such as PTFE), the carbon sheet has flexibility in bonding the carbon fiber. Therefore, this carbon sheet has the advantage of having the flexibility to be wound up in a roll shape, and therefore has a roll transportability and is excellent in productivity.
JP 2000-136493 A

  According to the carbon sheet described above, there is flexibility in the bonding of carbon fibers, and the flexibility of winding up the carbon sheet in a roll shape, but when the carbon sheet is incorporated as a gas diffusion layer and a fuel cell as a gas diffusion layer, The pores existing inside the gas diffusion layer formed of the carbon sheet may be crushed.

  Further explanation will be added. FIG. 7 schematically shows a form in which this carbon sheet is used as a gas diffusion layer. As shown in FIG. 7, when assembled as a fuel cell, the gas diffusion layer 100X made of the above-described carbon sheet is sandwiched by applying pressure to the gas distribution plate 200X. For this reason, the gas diffusion layer 100X is pressurized by the convex part 220X which forms the gas flow path 210X of the gas distribution plate 200X. Therefore, in the region 110X of the gas diffusion layer 100X that faces the convex portion 220X of the gas flow plate 200X, the frequency with which the internal pores 111X are crushed may increase.

  Here, the pores 111X formed in the gas diffusion layer 100X have a function of supplying a reaction gas such as a fuel gas or an oxidant gas and a function of discharging water generated by the power generation reaction. For this reason, when the frequency with which the pores 111X are crushed is high, there is a problem that the above-described function is lowered and it is difficult to obtain the target power generation performance of the fuel cell.

  Furthermore, since the gas diffusion layer 100X formed of the above-described carbon sheet is flexible in the thickness direction as described above, when the gas diffusion layer 100X is sandwiched between the gas flow distribution plates 200X, a simulation is performed in FIG. As shown in FIG. 5, a part 102X of the gas diffusion layer 100X swells into the gas flow path 210X of the gas flow distribution plate 200X, and the cross-sectional area of the gas flow path 210X of the gas flow distribution plate 200X is larger than the target flow path cross-section There is a risk of making it too small. In this case, there is a possibility that the gas supply performance through the gas flow path 210X of the gas flow distribution plate 200X is not sufficient.

The present invention has been made in view of the above-described circumstances, and it is possible to prevent the pores of the gas diffusion layer from being excessively crushed and the cross-sectional area of the gas flow path of the gas distribution plate from being excessively reduced. preferred fuel cell gas diffusion layer, and to provide a manufacturing method and a fuel cell gas diffusion layer laminated structure of it.

A gas diffusion layer for a fuel cell according to the present invention of aspect 1 has a first opposing surface facing the gas flow plate and a second opposing surface facing the catalyst layer, and a fuel having pores having gas diffusibility The gas diffusion layer for a battery is provided with a thickness holding material that suppresses the collapse of the thickness of the gas diffusion layer, where the thickness or diameter of the thickness holding material is A, and the thickness when the gas diffusion layer is used. When B, A / B = 1.5 to 0.3 is set . The gas diffusion layer includes a thickness holding material that suppresses the collapse of the thickness. For this reason, excessive compression of the gas diffusion layer is suppressed.

Production method for a fuel cell gas diffusion layer according to the present invention of aspect 2, and inhibits collapse of the thickness of the gas diffusion layer and a loss can be lost material and conductive material having a conductivity as a main component A step of preparing a liquid material including a thickness holding material, and separating and depositing a solid content from the liquid material, thereby forming a sheet having a conductive material and a disappearing material as main components and carrying the thickness holding material. The sheet forming step and the pore forming step for forming the gas diffusion layer having gas diffusibility by eliminating the disappearing substance contained in the sheet to form pores inside the sheet are sequentially performed ,
The gas diffusion layer that has been subjected to the pore formation step includes a thickness holding material that suppresses the collapse of the thickness of the gas diffusion layer. The thickness or diameter of the thickness holding material is A, and the use of the gas diffusion layer When the thickness at the time is B, A / B = 1.5 to 0.3 is set .

  The thickness holding material contained in the liquid material is carried on the gas diffusion layer. Although such a gas diffusion layer has moderate flexibility, the thickness of the gas diffusion layer is ensured when sandwiched in the thickness direction by the gas flow plate during use. Furthermore, when the gas diffusion layer is sandwiched between gas distribution plates, the pores of the gas diffusion layer are not easily crushed, and the gas diffusibility of the gas diffusion layer is ensured.

The gas diffusion layer laminated structure for a fuel cell according to the present invention of aspect 3 has (i) a first opposing surface that faces the gas distribution plate and a second opposing surface that faces the catalyst layer, and has a gas diffusibility. A fuel cell gas diffusion layer having holes, (ii) a gas flow path through which a reaction gas flows, and a protrusion projecting toward the fuel cell gas diffusion layer so as to form the gas flow path, and a fuel And (iii) the fuel cell gas diffusion layer has a thickness of the gas diffusion layer due to the convex portion of the gas distribution plate. A thickness holding material that suppresses crushing is provided. When the thickness or diameter of the thickness holding material is A and the thickness when the gas diffusion layer is used is B, A / B = 1.5 to 0 .3 is set. The gas diffusion layer includes a thickness holding material that suppresses the collapse of the thickness. For this reason, even when the gas diffusion layer is sandwiched between gas distribution plates, excessive compression of the gas diffusion layer due to the convex portions of the gas distribution plate is suppressed.

The gas diffusion layer according to the present invention includes a thickness holding material that suppresses collapse of the thickness. For this reason, excessive compression of the gas diffusion layer is suppressed. For this reason, even when the gas diffusion layer is sandwiched between the gas flow plates, it is possible to prevent the pores having gas diffusibility formed inside the gas diffusion layer from being crushed excessively. Furthermore, even when the gas diffusion layer is sandwiched between the gas flow distribution plates, it is possible to prevent a part of the gas diffusion layer from expanding into the flow path of the gas flow path where the gas flow distribution plate is formed. . As a result, it can suppress that a gas flow path becomes small too much.

  In addition, according to the method for manufacturing a gas diffusion layer according to the present invention, the thickness maintaining material included in the liquid material is supported on the sheet, that is, the gas diffusion layer. The gas diffusion layer carrying the thickness maintaining material is suppressed from being excessively compressed in the thickness direction. For this reason, even when the gas diffusion layer is sandwiched between gas distribution plates, it is possible to prevent the pores formed inside the gas diffusion layer from being crushed excessively. Furthermore, even when the gas diffusion layer is sandwiched between the gas flow distribution plates, it is possible to prevent a part of the gas diffusion layer from expanding into the flow path of the gas flow path where the gas flow distribution plate is formed. . As a result, it can suppress that a gas flow path becomes small too much.

According to the gas diffusion layer laminated structure for a fuel cell according to the present invention, even when the gas diffusion layer is sandwiched between gas flow plates, the gas diffusible pores formed inside the gas diffusion layer are provided. Excessive crushing can be suppressed. Furthermore, even when the gas diffusion layer is sandwiched between the gas flow distribution plates, it is possible to prevent a part of the gas diffusion layer from expanding into the flow path of the gas flow path where the gas flow distribution plate is formed. . As a result, it can suppress that a gas flow path becomes small too much.

  According to the present invention, the gas diffusion layer includes the thickness holding material that suppresses the collapse of the thickness thereof. For this reason, excessive compression of the gas diffusion layer is suppressed. If the thickness or diameter of the thickness-holding material is A and the thickness of the gas diffusion layer is B when the gas diffusion layer is assembled to a fuel cell, the thickness will be maintained if the A / B value is excessively large. The thickness or diameter of the material is too larger than the thickness of the gas diffusion layer, which may cause damage to the gas distribution plate and the catalyst layer. On the other hand, if the value of A / B is excessively small, the thickness or diameter of the thickness holding material is too small than the thickness of the gas diffusion layer, and the function of the thickness holding material cannot be sufficiently exhibited, There is a risk of excessive compression in the thickness direction.

  In consideration of such circumstances, it is possible to adopt a mode set in the range of A / B = 1.5 to 0.3. In particular, A / B is in the range of 1.4 to 0.5, in the range of 1.3 to 0.7, more preferably in the range of 1.2 to 0.7, and in the range of 1.1 to 0.8. , 1.0 to 0.8 can be set. The upper limit value of A / B can be exemplified as 1.5, 1.2, 1.0, and the lower limit value can be exemplified as 0.7, 0.8, 0.9, but is not limited thereto. Absent. In addition, about the value of A / B, in order to suppress damage to a gas distribution plate or a catalyst layer, it can be 1.0 or less.

  The thickness or diameter of the thickness-retaining material (incorporated in the gas diffusion layer) varies depending on the thickness of the gas diffusion layer, etc., in order to correspond to the thickness of the gas diffusion layer when used in a fuel cell. However, 40-1000 micrometers, 50-500 micrometers, 100-400 micrometers, and 100-300 micrometers are illustrated, for example. However, it is not limited to these.

  The thickness maintaining material can be in the form of particles or fibers, but in order to obtain the flexibility of the gas diffusion layer, it is preferably in the form of particles. Examples of the particle shape include at least one of spherical, pseudo-spherical, elliptical, pseudo-elliptical, elliptical, pseudo-ellipse, and polygonal. In the thickness retaining material, when L1 is a diameter or width in one direction and L2 is a diameter or width in a direction orthogonal to one direction, L1 / L2 corresponding to sphericity is 0.5 to 3.0. , 0.7 to 2.0, or 0.9 to 1.1. However, it is not limited to this. If the thickness holding material is spherical or pseudo-spherical, it is advantageous to increase the flexibility of the gas diffusion layer.

The thickness holding material can be exemplified by a form in which at least one of ceramic, metal and resin is used as a base material. Ceramics may be oxide-based or non-oxide-based. Examples of non-oxides include nitrides, carbides, and borides. Examples of ceramics include zirconia, alumina, silica, mullite, cordierite, silicon carbide, silicon nitride, boron nitride, yttria, ceria, aluminum nitride, zircon (composition formula: Zr [SiO ₂ ]), aluminum titanate, Examples include at least one of titania, magnesia, titanium boride, tungsten carbide (WC), and glass. The zirconia may be stabilized zirconia (FSZ) added with a stabilizer or partially stabilized zirconia (PSZ). Examples of the stabilizer include Y ₂ O ₃ , MgO, CeO ₂ , and Al ₂ O ₃ . The ceramic may be solid or hollow. Examples of the metal include ferrous, non-ferrous, and intermetallic compounds. As the iron system, an alloy steel system with good corrosion resistance is preferable, but in some cases, a carbon steel system can be used.

  The resin may be a thermosetting resin or a thermoplastic resin. Examples of the thermosetting resin include at least one of phenol resin, epoxy resin, diallyl phthalate resin, unsaturated polyester resin, furan resin, urea resin, alkyd resin, melamine resin, and silicone resin. Examples of the thermoplastic resin include at least one of polyphenylene sulfide (PPS) resin, polyether sulfone (PES) resin, and polyether ether ketone (PEEK) resin.

  A form in which at least a part of the thickness maintaining material is covered with a film can be exemplified. An example of the coating is a coating with good corrosion resistance. An example of a film having good corrosion resistance is a gold film. When the thickness holding material is a metal, at least a part of the thickness holding material can be covered with a film having good corrosion resistance.

  The mixing ratio of the thickness maintaining material in the gas diffusion layer can be appropriately selected. When the blending ratio of the thickness maintaining material is large, the ratio of the base material (for example, carbon fiber) of the gas diffusion layer is relatively decreased, and the original performance of the gas diffusion layer may be decreased. Moreover, when the blending ratio of the thickness maintaining material is small, the ratio of the base material of the gas diffusion layer is relatively increased, but the gas diffusion layer may be excessively compressed in the thickness direction. Therefore, when the base material (for example, carbon fiber) of the gas diffusion layer is set to 1 in relative display, the thickness holding material such as zirconia particles is in the range of 1/30 to 1/1 by weight ratio with respect to the base material. A form blended in the range of / 10 to 2/3, particularly in the range of 1/6 to 1/2 can be adopted. However, it is not limited to these.

According to the method of the present invention, a step of preparing a liquid material including a conductive material having conductivity and a disappearable material that can be lost as a main component and a thickness holding material that suppresses the collapse of the gas diffusion layer; By separating solids from the sheet, a sheet forming step of forming a sheet mainly composed of a conductive substance and a disappearing substance by deposition of solids, and disappearing the disappearing substance contained in the sheet to form pores inside the sheet And a pore forming step for forming the. Furthermore, it is preferable to impregnate the sheet with a water repellent material between the sheet forming step and the pore forming step. The water repellent material has a function of suppressing the gas passage from being clogged with water. Examples of the water repellent material include fluororesins such as tetrafluoroethylene (PTFE), tetrafluoroethylene / ethylene copolymer (ETFE), and tetrafluoroethylene / perfluoroalkoxyethylene copolymer (PFA).

  The conductive material having conductivity contained in the liquid material as the starting material may be fibrous or particulate. As the conductive material, carbon-based materials can be generally used in consideration of corrosion resistance, conductivity, and the like. Examples of carbon-based materials include carbon fibers and carbon particles. Examples of the conductive fiber such as carbon fiber include those having a diameter of 2 to 50 μm, particularly 7 to 18 μm, and a length of 1 to 50 mm, particularly 3 to 24 mm, but are not limited thereto.

  As the erasable substance contained in the liquid material, an organic substance that burns down by heating to form pores can be employed. Examples of such organic substances include plant organic substances such as pulp. Pulp is advantageous for capturing conductive materials such as carbon fibers during papermaking. The pulp has the above-described capturing ability and water absorption. The liquid material as the starting material includes a thickness maintaining material. The thickness holding material contained in the liquid material is carried on the sheet together with a conductive substance such as carbon fiber. As the thickness maintaining material contained in the liquid material as the starting material, at least one of the above-described ceramics and metals can be used as a base material.

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. The example is applied to a solid polymer electrolyte fuel cell. The electrode of this fuel cell is formed by laminating a gas diffusion layer and a catalyst layer.

Example 1
Short fibers of carbon fiber (conductive material) functioning as a base material for the gas diffusion layer (typically 13 μm in diameter and 3 mm in length), pulp (disappearing material), and zirconia particles (thickness retention) 2) is mixed with water in the container at a predetermined ratio and beaten in water to uniformly disperse carbon fibers, pulp, and zirconia particles. Was made. Here, the particle diameter of the zirconia particles is 200 μm, that is, smaller than the length of the carbon fiber and larger than the diameter of the carbon fiber. The shape of the zirconia particles was spherical with high sphericity. In the zirconia particles, when L1 is a diameter or width in one direction and L2 is a diameter or width in a direction orthogonal to one direction, L1 / L2 is 0.95 to 1.06. As for the diameter or width of the zirconia particles, 20 particles were measured by microscopic observation.

  As the above-mentioned predetermined ratio, the weight ratio was carbon fiber: pulp: zirconia particles = 6: 4: 1. That is, when the carbon fiber which is the base material of the gas diffusion layer is set to 1 in relative display, the zirconia particles are blended by about 1/6 in weight ratio with respect to the carbon fiber.

  The papermaking slurry 10 was subjected to papermaking using a mesh member. That is, the solid content and the liquid content contained in the papermaking slurry were separated by a mesh member to produce a thin sheet 20 having a thickness of about 0.3 mm (see FIG. 4). Therefore, the thin sheet 20 contains carbon fiber, pulp, and zirconia particles as main components. During the papermaking process, when the papermaking slurry 10 does not contain pulp, it becomes difficult to capture the carbon fibers and zirconia particles. Since pulp is contained in the papermaking slurry 10, carbon fibers and zirconia particles are efficiently supported on the thin sheet 20. Thus, the pulp can also function as a capture promoting substance that captures carbon fibers and zirconia particles.

  FIG. 3 shows a state where the thin sheet 20 formed by papermaking is being conveyed in a roll. As described above, the thin sheet 20 is conveyed while being bent between the plurality of rolls 500 in the manufacturing process. At this time, since the zirconia carried on the thin sheet 20 is not in the form of long fibers but in the form of fine particles, the thin sheet 20 is rich in flexibility. Therefore, the thin sheet 20 can be easily rolled and conveyed between the rolls 500.

  In this example, a paste formed by mixing and dispersing the conductive material carbon black (Vulcan XC-72) and water repellent material (PTFE dispersion Daikin Industries D-1) at a weight ratio of 2: 1 was used. . This paste was impregnated into the thin sheet 20 from the surface to the inside by roll coating (see FIG. 4). Thereafter, the thin sheet 20 impregnated with the paste was dried, heated and held at a predetermined temperature (380 ° C.) in an air atmosphere, and fired. The pulp contained in the thin sheet 20 was burned out (disappeared) by firing, and the marks of the pulp were formed as pores 22 (see FIG. 5). Since the pulp is fibrous, it is assumed that the pores 22 which are pulp marks basically have a shape corresponding to the form of carrying the pulp and become continuous pores with good gas diffusibility.

  Thereafter, the thin sheet 20 was pressed in the thickness direction by hot pressing. Thus, the thickness was adjusted to be uniform in the plane, and the porous gas diffusion layer 100 (thickness: about 200 μm) according to the example was formed. The gas diffusion layer 100 basically includes carbon fibers as a conductive material, carbon black as a conductive material, water repellent material (PTFE), and zirconia particles as main components.

  According to the present embodiment, the papermaking slurry 10 (liquid material) as a starting material contains zirconia particles that can function as a thickness maintaining material in addition to carbon fibers and pulp. Therefore, the zirconia particles can be supported on the thin sheet 20 to be the gas diffusion layer 100.

  FIG. 1 schematically shows a state in which a gas diffusion layer 100 together with a gas flow plate 200 is incorporated in a solid polymer electrolyte fuel cell. As shown in FIG. 1, catalyst layers 410 and 420 are disposed between a gas diffusion layer 100 made of a carbon sheet and a solid polymer electrolyte membrane 400. The catalyst layers 410 and 420 include, as main components, a catalyst material such as platinum, an electron conductive material such as carbon black, and an electrolyte material. As shown in FIG. 1, the gas diffusion layer 100 made of a carbon sheet includes a first facing surface 100 f that faces the gas distribution plate 200 and a second facing surface 100 s that faces the catalyst layers 410 and 420.

  As shown in FIG. 1, the gas diffusion layer 100 is sandwiched between gas distribution plates 200 from both sides in the thickness direction. In this case, the convex part 220 which forms the gas flow path 210 of the gas distribution plate 200 is formed, and the gas diffusion layer 100 is pressurized by the front end surface 220a of the convex part 220 in the thickness direction. Here, the gas diffusion layer 100 made of a carbon sheet contains zirconia particles having a particle size corresponding to the thickness of the gas diffusion layer 100 assembled in the fuel cell as a thickness maintaining material. For this reason, in the area | region 101 which faces the convex part 220 of the gas distribution plate 200 among the gas diffusion layers 100, a possibility that the internal pore 22 may be crushed is suppressed.

  Here, the pores 22 formed in the gas diffusion layer 100 have a gas permeation function for allowing a reaction gas such as a fuel gas or an oxidant gas to pass therethrough, and a water discharge function for discharging water generated by the power generation reaction. Have In this embodiment, excessive crushing of the pores 22 is suppressed by the zirconia particles, so that both the above-described gas permeation function and water discharge function are ensured well, and the power generation performance of the fuel cell is improved.

  Further, even when the gas diffusion layer 100 is sandwiched in the thickness direction by the gas flow distribution plate 200, unlike the conventional embodiment shown in FIG. Swelling in the path 210 is suppressed. Therefore, it is advantageous to secure the flow path cross-sectional area of the gas flow path 210 of the gas distribution plate 200. Therefore, the gas supply property through the gas flow path 210 of the gas distribution plate 200 is ensured satisfactorily.

  In addition, according to the present embodiment, since the zirconia particles as the thickness maintaining material are not fibrous, the flexibility of the gas diffusion layer is not impaired. Therefore, the roll transportability, which is an advantage of the papermaking method, is ensured in the manufacturing process, and productivity is ensured.

(Example 2)
The second embodiment has basically the same configuration as the first embodiment and has the same function and effect. In Example 2, the same kind of zirconia particles as in Example 1 were used, the particle diameter was 200 μm, and the shape was spherical. The ratio of the slurry 10 was set to carbon fiber: pulp: zirconia particles = 6: 4: 3 by weight so as to increase the ratio of zirconia particles than in Example 1. That is, when the carbon fiber that is the base material of the gas diffusion layer is set to 1 in relative display, the zirconia particles are blended by about 1/2 with respect to the carbon fiber in weight ratio. The thickness of the gas diffusion layer 100 of Example 2 is about 200 μm.

Example 3
The third embodiment has basically the same configuration as that of the first embodiment and has the same function and effect. In Example 3, a papermaking slurry 10 (liquid material) in which carbon fibers, pulp, and glass particles were uniformly dispersed was prepared. The glass particles had a particle size of 200 μm and a spherical shape. The ratio was carbon fiber: pulp: glass particles = 6: 4: 1 by weight. That is, when the carbon fiber that is the base material of the gas diffusion layer is set to 1 by relative display, the glass particles are blended by about 1/6 in weight ratio with respect to the carbon fiber. In the glass particles, when the diameter or width in one direction is L1, and the diameter or width in a direction orthogonal to the one direction is L2, L1 / L2 is 0.88 to 1.11. The thickness of the gas diffusion layer 100 of Example 3 is about 200 μm.

(Example 4)
The fourth embodiment has basically the same configuration as that of the third embodiment and has the same function and effect. In Example 4, a papermaking slurry 10 (liquid material) in which carbon fibers, pulp, and glass particles were uniformly dispersed was prepared. The glass particles had a particle size of 200 μm and a spherical shape. The ratio was set to carbon fiber: pulp: glass particles = 6: 4: 3 in a weight ratio so as to increase the glass particles as compared with the case of Example 3. That is, when the carbon fiber which is the base material of the gas diffusion layer is set to 1 in relative display, the glass particles are blended by about 1/2 with respect to the carbon fiber in a weight ratio. The thickness of the gas diffusion layer 100 of Example 4 is about 200 μm.

(Example 5)
The fifth embodiment has basically the same configuration as that of the first embodiment and has the same function and effect. In Example 5, instead of zirconia particles, metal particles (thickness retaining material) coated with a coating having corrosion resistance by gold vapor deposition were used. The metal particles are made of stainless steel, have a particle size of 200 μm, and have a spherical shape. The ratio of the slurry 10 was carbon fiber: pulp: metal particles = 6: 4: 3 by weight. That is, when the carbon fiber which is the base material of the gas diffusion layer is set to 1 in relative display, the metal particles having the coating are blended by about 1/2 with respect to the carbon fiber in a weight ratio. In the metal particles having a coating, L1 / L2 is 0.96 to 1.04, where L1 is a diameter or width in one direction and L2 is a diameter or width in a direction orthogonal to one direction. The thickness of the gas diffusion layer 100 of Example 5 is about 200 μm.

(Comparative example)
The comparative example was basically produced in the same manner as in Example 1. However, the papermaking slurry according to the comparative example does not contain zirconia particles, glass particles, or metal particles. In the comparative example, first, short fibers of carbon fibers (typical size is 13 μm in diameter and 3 mm in length) and pulp are mixed at a predetermined weight ratio (6: 4) and beaten in water. Thus, a papermaking slurry in which carbon fibers and pulp were uniformly dispersed was produced. The papermaking slurry was processed into a net-like member, and the liquid content and solid content contained in the papermaking slurry were separated to produce a thin sheet having a thickness of about 0.3 mm as in the above example. A paste in which carbon black (Vulcan XC-72) and water repellent material (PTFE dispersion Daikin Industries D-1) were mixed and dispersed at a weight ratio of 2: 1 was used. This thin sheet was impregnated into the thin sheet from the surface by roll coating, dried and fired at 380 ° C. to burn (disappear) the pulp contained in the thin sheet. Thereafter, the sheet was hot pressed to adjust the thickness to be uniform within the surface, and a gas diffusion layer (about 200 μm) according to a comparative example was obtained.

(test)
The thickness retention rate of the gas diffusion layer obtained by the method as described above was measured. In this case, the load when the gas diffusion layer was incorporated into the fuel cell as an electrode was pressurized with a press device in the thickness direction of the gas diffusion layer, and the change in the thickness of the gas diffusion layer was tested. The thickness of the gas diffusion layer was measured with a dial gauge. FIG. 6 shows the test results. The maximum load was 4 MPa (≈41 kgf / cm ² ). The horizontal axis in FIG. 6 indicates the load, and the vertical axis indicates the thickness retention rate. The thickness retention rate of 100% corresponds to the thickness of the gas diffusion layer when no load is applied. A thickness retention of 90% means that the thickness is 10% thinner than the thickness when no load is applied. As shown by the characteristic line in FIG. 6, according to the comparative example that does not contain the thickness holding material, the thickness holding ratio is drastically reduced even when the load is small. On the other hand, in Examples 1-5 containing a thickness holding material, there is little fall of thickness retention. In particular, in Examples 4 and 2, the decrease in thickness retention is small. In Example 4, carbon fiber: pulp: glass particles = 6: 4: 3 by weight ratio. In Example 2, the weight ratio is carbon fiber: pulp: zirconia particles = 6: 4: 3.

(Other)
The gas diffusion layer may be loaded with zirconia particles and glass particles in combination. Further, at least one of zirconia particles and glass particles may be used in combination with resin particles and / or metal particles having a coating. The gas diffusion layer is not limited to those formed by the papermaking method, and can be applied to gas diffusion layers formed by other manufacturing methods. In addition, the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within a range not departing from the gist.

  The present invention can be used in a method for producing a gas diffusion layer for a solid polymer electrolyte fuel cell.

It is sectional drawing which shows typically the fuel cell incorporating the gas diffusion layer which concerns on an Example. It is a block diagram which shows typically the process in which carbon fiber, a pulp, and a zirconia particle | grain are mix | blended and the slurry for papermaking is formed. It is a block diagram which shows the state which is carrying out the roll conveyance of the thin sheet. It is a block diagram which shows typically the form which impregnates the thin sheet | seat from the surface with the paste containing carbon black and a water repellent material. It is a block diagram which shows the gas diffusion layer formed with the carbon sheet which has a pore. It is a graph which shows the test result of thickness retention about the gas diffusion layer which concerns on an Example, and the gas diffusion layer which concerns on a comparative example. It is sectional drawing which shows typically the fuel cell incorporating the gas diffusion layer which concerns on a prior art.

In the figure, 100 is a gas diffusion layer, 200 is a gas distribution plate, 210 is a gas flow path, 220 is a convex portion, 10 is a slurry, 20 is a thin sheet, and 22 is a pore.

Claims (8)

In the gas diffusion layer for a fuel cell, having a first opposing surface facing the gas distribution plate and a second opposing surface facing the catalyst layer, and having pores having gas diffusibility,
A thickness holding material that suppresses the collapse of the thickness of the gas diffusion layer is provided, and the thickness or diameter of the thickness holding material is A, and the thickness when the gas diffusion layer is used is B. A gas diffusion layer for fuel cells, wherein A / B = 1.5 to 0.3 . Oite to claim 1, for a fuel cell gas diffusion layer, wherein the thickness of the holding material is particulate. According to claim 1 or 2, wherein the thickness of the holding material ceramics, metals and fuel cell gas diffusion layer, characterized in that it is formed as a base material at least one of the resin. Preparing a liquid containing a thick holding material suppresses and collapse of the thickness of the gas diffusion layer comprises a conductive material having conductivity and a loss can be loss materials as a main component, from the liquid product A sheet forming step of forming a sheet containing the conductive material and the disappearing material as main components and carrying the thickness holding material by separating and depositing solids, and the disappearance included in the sheet The pore formation step of forming a gas diffusion layer having gas diffusibility by eliminating the substance and forming pores inside the sheet is sequentially performed ,
The gas diffusion layer that has performed the pore formation step includes the thickness holding material that suppresses the collapse of the thickness of the gas diffusion layer, and the thickness or diameter of the thickness holding material is A, A manufacturing method of a gas diffusion layer for a fuel cell , wherein A / B = 1.5 to 0.3, where B is a thickness when the gas diffusion layer is used . 5. The fuel cell gas diffusion layer according to claim 4 , wherein the thickness holding material contained in the liquid material is formed using at least one of ceramic, metal, and resin as a base material. Production method. 6. The method for producing a gas diffusion layer for a fuel cell according to claim 5 , wherein the thickness maintaining material contained in the liquid material is in the form of particles. 7. The method of manufacturing a fuel cell gas diffusion layer according to claim 5, wherein the thickness holding material is at least one of zirconia and glass . (I) a gas diffusion layer for a fuel cell having a first opposing surface facing the gas flow plate and a second opposing surface facing the catalyst layer and having pores having gas diffusibility; and (ii) a reactive gas A gas distribution having a flowing gas channel and a convex portion projecting toward the fuel cell gas diffusion layer so as to form the gas channel, and sandwiching the fuel cell gas diffusion layer in the thickness direction thereof (Iii) The fuel cell gas diffusion layer includes a thickness holding material that suppresses the thickness of the gas diffusion layer from being crushed due to the convex portion of the gas flow distribution plate. When the thickness or diameter of the thickness holding material is A and the thickness when the gas diffusion layer is used is B, A / B = 1.5 to 0.3 is set. A gas diffusion layer laminate structure for a fuel cell.

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