JP5417819B2 - Fuel cell separator and method for producing the same - Google Patents

Description

  The present invention relates to a fuel cell separator and a method for producing the same. Specifically, the present invention relates to a separator for a fuel cell that can uniformize the supply of reaction gas to electrodes arranged on both sides of an electrolyte membrane, and a method for manufacturing the same.

  In recent years, in response to social demands and trends against the background of energy and environmental problems, fuel cells that operate at room temperature and obtain high output have attracted attention as power sources for electric vehicles and stationary power sources. A fuel cell is a clean power generation system in which the product of the electrode reaction is water and has almost no adverse effect on the global environment. Fuel cells include polymer electrolyte fuel cells (PEFC), phosphoric acid fuel cells (PAFC), alkaline fuel cells (AFC), solid oxide fuel cells (SOFC), and molten carbonate fuel cells (MCFC). )and so on. Among them, the polymer electrolyte fuel cell is expected as a power source for an electric vehicle because it operates at a relatively low temperature to obtain a high output.

  The polymer electrolyte fuel cell generally has a structure in which a membrane electrode assembly is sandwiched between separators. The membrane / electrode assembly is formed by sandwiching a solid electrolyte membrane between a pair of catalyst layers and, if necessary, a gas diffusion layer. The separator is in contact with the electrode and used for collecting current from the electrode, and is provided with a gas flow path for supplying gas and a cooling water flow path.

As such a fuel cell separator, there has been disclosed one that forms a reaction gas flow path by providing a plurality of protrusions on the surface of a metal separator (see, for example, Patent Document 1).
JP 2005-190710 A

  However, the protrusion in the separator of Patent Document 1 is formed by press-molding a metal plate. Therefore, it is difficult for the reactive gas to reach the portion of the gas diffusion layer that contacts the protrusion. Therefore, the arrival of the reaction gas to the catalyst layer in contact with the gas diffusion layer is hindered, and there is a problem that a sufficient reaction region cannot be secured and the power generation performance is lowered.

  The present invention has been made in view of such problems of the prior art. The object is to provide a fuel cell separator and a method of manufacturing the fuel cell separator that can uniformize the supply of the reaction gas to the gas diffusion layer and the catalyst layer and prevent a decrease in power generation performance. It is in.

The fuel cell separator of the present invention includes a separator base material, a separator base material, a reaction gas flow path formed on the surface of the separator base material, and a plurality of protrusions made of a porous body. Further, the protrusion contains conductive particles having a particle diameter of 0.5 μm to 50 μm, and the protrusion has a porosity of 65 to 90%. The plurality of protrusions are provided in a staggered manner with respect to the reaction gas flow direction, and are connected to the straight line connecting the centers of the two protrusions adjacent to each other along the reaction gas flow direction and upstream of the reaction gas in the two protrusions. An angle formed by a gas stream line perpendicular to the surface of the formed protrusion and parallel to the reaction gas flow direction is 0 to 50 °.

  The manufacturing method of the separator for fuel cells of this invention has the process of forming the protrusion precursor by coating the slurry on a separator base material by screen printing, and the process of preparing the slurry containing electroconductive particle. Furthermore, it has the process of forming protrusion by drying the separator base material with which slurry was applied.

  In the separator for a fuel cell of the present invention, since the protrusion provided on the separator substrate is a porous body, the reaction gas permeates to the gas diffusion layer and the catalyst layer facing the protrusion, so that a reaction region can be secured, Power generation performance is improved. Moreover, the manufacturing method of the separator for fuel cells of this invention can form the said protrusion cheaply and easily by the screen printing method.

  Hereinafter, embodiments of the present embodiment will be described in detail with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

  FIG. 1A shows a configuration of a fuel cell (single cell) including the separator according to the present embodiment. As shown in FIG. 1A, the fuel cell 1 includes a membrane electrode assembly 5 in which an air electrode 3 and a fuel electrode 4 are joined and integrated on both sides of a solid polymer electrolyte membrane 2. The air electrode 3 has a two-layer structure including an air electrode catalyst layer 3 a and an air electrode gas diffusion layer 3 b, and the air electrode catalyst layer 3 a is in contact with one surface of the solid polymer electrolyte membrane 2. Similarly, the fuel electrode 4 has a two-layer structure including a fuel electrode catalyst layer 4a and a fuel electrode gas diffusion layer 4b. The fuel electrode catalyst layer 4a is in contact with the other surface of the solid polymer electrolyte membrane 2. Yes. An air electrode separator 6 and a fuel electrode separator 7 are installed outside the air electrode 3 and the fuel electrode 4, respectively. The air electrode separator 6 and the fuel electrode separator 7 form an oxidant gas channel 6a, a fuel gas channel 7a, and a cooling water channel 8.

  In the fuel cell 1, an air electrode 3 and a fuel electrode 4 are arranged on both sides of a solid polymer electrolyte membrane 2, and are usually joined together by a hot press method to form a membrane electrode assembly, and then a membrane electrode The air electrode separator 6 and the fuel electrode separator 7 are disposed on both sides of the joined body 5 for manufacturing. In the fuel cell 1, a fuel gas containing hydrogen is supplied to the fuel electrode 4 side, and an oxidant gas such as air containing oxygen is supplied to the air electrode 3 side. Thereby, an electrochemical reaction occurs at the contact surface between the solid polymer electrolyte membrane 2 and the air electrode catalyst layer 3a and the fuel electrode catalyst layer 4a.

  FIG. 2 shows the fuel electrode separator 7 according to this embodiment. Hereinafter, the configuration of the fuel electrode separator 7 will be described, but the air electrode separator 6 has the same configuration as the fuel electrode separator 7. The separator 7 includes a flat separator base material 10. A fuel gas supply manifold 11a for supplying fuel gas to the separator 7 is formed at one end in the longitudinal direction (X direction) of the separator substrate 10, and a fuel gas discharge manifold 11b is formed on the diagonal line. An oxidant gas supply manifold 12a for supplying an oxidant gas to the separator 6 is formed at the other end in the longitudinal direction of the separator substrate 10, and an oxidant gas discharge manifold 12b is formed on the diagonal line. Yes.

  In the fuel electrode separator 7 of this embodiment, a plurality of protrusions 13 are formed on one surface of the separator substrate 10. The protrusion 13 is made of a porous material, and the fuel gas supplied through the fuel gas supply manifold 11 a can pass through the protrusion 13 and reach the gas diffusion layer 4 b facing the protrusion 13.

  Specifically, the separator of Patent Document 1 has a plurality of protrusions formed on the surface, and the protrusions are formed by press-molding a metal plate. Therefore, the protrusion itself has no fuel gas permeability. Therefore, as shown in FIG. 1B, it is difficult for the fuel gas to reach the portion 9 facing the protrusion in the gas diffusion layer. In this case, since it is difficult for the fuel gas to be supplied to the catalyst layer existing below the gas diffusion layer, the oxidation reaction of the fuel gas hardly occurs in the vicinity of the portion 9 and the power generation efficiency is lowered. However, as for the separator 7 of this embodiment, the protrusion 13 is comprised with the porous body. Therefore, as shown by the arrow in FIG. 1 (b), the fuel gas enters the inside of the projection 13 from the fuel gas flow path 7a, and further, from the inside of the projection 13, the portion 9 facing the projection 13 in the gas diffusion layer 4b. Is supplied with gas. Therefore, the oxidation reaction of the fuel gas occurs even in the catalyst layer 4a existing in the vicinity of the portion 9, and the power generation efficiency is improved.

  In addition, as shown in FIG. 2, the separator 7 forms a fuel gas flow path by forming a plurality of protrusions 13 on one surface of the separator substrate 10. Specifically, the fuel gas supplied to the separator 7 through the fuel gas supply manifold 11a diffuses into the gas diffusion layer 4b through the protrusions 13 and reaches the catalyst layer 4a. Thereafter, the fuel gas is oxidized in the catalyst layer, and the reacted fuel gas is discharged from the fuel gas discharge manifold 11b on the diagonal line of the fuel gas supply manifold 11a. Thus, in the fuel electrode of the fuel cell 1, since the fuel gas is diffused not only by the gas diffusion layer 4b but also by the porous protrusion 13, the fuel gas can be supplied uniformly to the entire catalyst layer 4a. Furthermore, since the protrusion 13 has a high gas diffusing ability, the thickness of the gas diffusion layer 4b can be made thinner than before, and the cost can be reduced. Further, since the gas flow path can be formed by the protrusions 13, it is not necessary to form a gas flow path groove, which is essential for the conventional separator, and metal forming therefor is not necessary.

  Since the protrusion 13 is made of a porous body, the porosity of the protrusion 13 is preferably 65 to 90%. When the porosity is less than 65%, the gas permeability is lowered, and there is a possibility that sufficient gas diffusion ability cannot be obtained. Moreover, when the porosity exceeds 90%, the strength of the protrusions may be reduced. The porosity is more preferably 70 to 90%. The porosity indicates the ratio of the pores to the apparent volume of the porous body constituting the protrusion, and can be obtained by a mercury intrusion method. When calculating | requiring a porosity by the mercury intrusion method, the processus | protrusion 13 is isolate | separated from the separator base material 10, and it calculates | requires using a commercially available pore distribution measuring apparatus. Moreover, it is preferable that the pore diameter of the pore formed in the protrusion 13 is 0.1 μm to 10 μm. When the pore diameter is less than 0.1 μm, the drainage resistance becomes high and the drainage performance may be lowered. Further, when the pore diameter exceeds 10 μm or more, water tends to stay in the pores, and as a result, drainage performance may be deteriorated. More preferably, the pore diameter is 2 μm to 8 μm. The pore diameter can be determined by the mercury intrusion method.

  The separator 7 needs to have high electrical conductivity because it is necessary to take out electrons generated by the electrochemical reaction of the anode. Therefore, it is preferable that the protrusion 13 itself also has electrical conductivity. From this, it is preferable that the protrusion 13 contains conductive particles. Moreover, since the protrusion 13 is a porous body, the particle diameter of the conductive particles is preferably 0.5 μm to 50 μm. When the particle diameter is less than 0.5 μm, the conductive particles become dense, and pores necessary for the permeation of the fuel gas may not be obtained. Further, when the particle diameter exceeds 50 μm, the pores in the protrusions are reduced, and the fuel gas permeation path may be reduced. The particle diameter is more preferably 1 μm to 10 μm. In addition, in this specification, a particle diameter shows a median diameter (D50) and can be calculated | required by the laser diffraction scattering method.

  As the conductive particles, it is preferable to use conductive carbon particles, and it is particularly preferable to use carbon black. As carbon black, furnace black, lamp black, acetylene black, channel black, thermal black and the like can be used.

  Furthermore, not only the protrusion 13 but also the separator substrate 10 needs to have conductivity. As a material of the separator base material 10, a known separator material having high conductivity such as stainless steel, titanium, or carbon can be used.

  Further, the protrusion 13 can be formed in a columnar shape. In this case, the diameter of the cross section of the column is preferably 65 μm to 500 μm. When the diameter of the cylinder is less than 65 μm, the strength of the protrusion 13 may be insufficient. Further, when the diameter of the cylinder exceeds 500 μm, the permeability of the fuel gas into the protrusion 13 may be reduced. In addition, although the diameter of the protrusion 13 can be measured by using a microscope, it can be easily measured by using a digital fine scope.

  As shown in FIG. 3, the protrusions 13 on the separator substrate 10 can be arranged at equal intervals in both the X direction and the Y direction. Moreover, as shown in FIG. 4, it can also arrange | position in zigzag form along a X direction. In this case, the pitch P (distance) between the protrusions 13 adjacent to each other is preferably 150 μm to 1000 μm. When the pitch P between the protrusions 13 is less than 150 μm, the pressure loss of the fuel gas may be increased. Further, when the pitch P exceeds 1000 μm, it becomes difficult to uniformly supply the fuel gas to the entire catalyst layer 4a.

  The protrusion arrangement in FIG. 4 will be described in more detail. In FIG. 4, the plurality of protrusions 13 are arranged in a staggered manner at appropriate intervals on the surface of the separator substrate 10 to form a fuel gas flow path. Specifically, a plurality of projections 13 are arranged at a predetermined interval P in a direction substantially orthogonal to the longitudinal direction (X direction) of the separator substrate 10 to form one projection group 13A1. And this protrusion group 13A1 is provided with two or more predetermined spacing D1 toward X direction (protrusion group 13A2, 13A3). Further, the protrusions 13 adjacent in the X direction are shifted by a predetermined distance D2 in a direction orthogonal to the X direction. The predetermined distance D2 can be half the distance between the centers of adjacent protrusions 13 in the protrusion group 13A1.

  Such a staggered arrangement can be arranged not only based on the X direction but also based on the fuel gas distribution direction. Specifically, as shown in FIG. 5, a plurality of protrusions 13 are arranged at a predetermined interval P in a direction substantially orthogonal to the fuel gas flow direction F of the separator base material 10 to form one protrusion group 13A1. . And this protrusion group 13A1 is provided with two or more toward the fuel gas distribution direction F (protrusion group 13A2, 13A3). Further, the adjacent protrusions 13 in the fuel gas flow direction F are shifted by a predetermined distance D2 in a direction orthogonal to the fuel gas flow direction. The fuel gas distribution direction is a direction from the center of the fuel gas supply manifold 11a toward the center of the fuel gas discharge manifold 11b. 4 and 5, the gas pressure of the fuel gas in contact with the protrusions 13 is increased, and the fuel gas can easily penetrate into the protrusions. Therefore, the gas supply to the gas diffusion layer and the catalyst layer facing the protrusions is increased, and the power generation performance is improved.

  The staggered protrusions are preferably arranged as follows. A straight line L connecting the centers C of the two protrusions 13B and 13C adjacent to each other in the fuel gas flow direction F, and a surface perpendicular to the surface of the protrusion 13B formed on the upstream side of the fuel gas in the two protrusions 13B and 13C. The angle θ formed with the gas stream line G to be performed is preferably 0 to 50 °. Incidentally, the gas flow line G indicates the direction in which the fuel gas collides perpendicularly with the surface of the upstream projection 13B, and the gas flow line G and the fuel gas flow direction F are the same direction (parallel). By setting such an angle, the gas pressure of the fuel gas in contact with the protrusion 13 is further increased, and the fuel gas is likely to penetrate into the protrusion. In addition, when the said angle exceeds 50 degrees, the surface pressure of the fuel gas which strikes a protrusion reduces, and there exists a possibility that permeation into the protrusion of a fuel gas may fall. Incidentally, the angle θ is more preferably 0 to 10 °.

  As shown in FIG. 6, the protrusions 13 on the separator substrate 10 are arranged along the X direction, and the diameter of the protrusions may be gradually reduced from the fuel gas supply manifold 11 a toward the fuel gas discharge manifold 11 b. good. Further, as shown in FIG. 7, the density of the protrusions may be gradually decreased along the X direction from the fuel gas supply manifold 11a toward the fuel gas discharge manifold 11b. With such an arrangement, the flow rate of the fuel gas on the side of the fuel gas discharge manifold 11b where the consumption of the fuel gas has progressed can be lowered, and the gas pressure of the fuel gas can be raised. That is, as shown in FIGS. 6 and 7, by increasing the distance between the protrusions downstream of the fuel gas, the gas flow passage area (volume) increases, and as a result, the gas flow rate decreases. When the gas flow velocity decreases, the gas pressure increases according to Bernoulli's theorem. By increasing the gas pressure, the contact rate between hydrogen in the fuel gas and the catalyst layer is improved, so that the power generation characteristics can be improved.

  The protrusion 13 preferably has a flat cross section. Specifically, as shown in FIG. 8, in the cross section of the protrusion 13D, the length d1 in the direction orthogonal to the fuel gas flow direction F is longer than the length d2 in the fuel gas flow direction. Thereby, the shape of the surface on which the fuel gas collides becomes a blunt shape. Thus, when the protrusion has a blunt structure with respect to the flow of the fuel gas, the gas pressure of the fuel gas that hits the protrusion rises, and the fuel gas easily penetrates into the protrusion. Therefore, the gas supply to the gas diffusion layer and the catalyst layer facing the protrusions is increased, and the power generation performance is improved.

  As shown in FIG. 9, the protrusion 13 may have a plurality of convex portions 14 on the surface. By forming the plurality of convex portions 14, the surface of the projection 13 has a rough structure with many irregularities. As a result, as indicated by an arrow in FIG. 9, the gas is drawn into the protrusion, and the gas easily penetrates into the protrusion. Therefore, the gas supply to the gas diffusion layer and the catalyst layer facing the protrusions is increased, and the power generation performance is improved. In addition, it is preferable that protrusion amount P from the protrusion 13 in the convex part 14 is 25 micrometers or less. Moreover, it is preferable that this convex part 14 consists of the said electroconductive particle which contained in the processus | protrusion 13 and enlarged the particle diameter.

  As shown in FIG. 10, the protrusion 13 may have a configuration in which the diameter of the cross section increases from the separator base material side to the catalyst layer side. Specifically, the cross-sectional diameter of the second protrusion 13b in contact with the gas diffusion layer 4b can be made larger than the cross-sectional diameter of the first protrusion 13a on the separator side. With such a configuration, the gas flow path on the separator substrate side becomes large, and the gas can be supplied uniformly and entirely to the catalyst layer. Moreover, the discharge | emission property of produced water improves and electric power generation performance improves. In addition, it is preferable that the diameter of the cross section of the 1st projection part 13a is 1/2 or more of the diameter of the cross section of the 2nd projection part 13b. If it is less than ½, the strength of the protrusions may be reduced. As a method of forming the protrusion as shown in FIG. 10, first, as shown in FIG. 10A, first, the first protrusion 13a having a small cross-sectional diameter is formed by a screen printing method. Thereafter, as shown in FIG. 10B, the second protrusion 13b is formed on the first protrusion 13a by the same screen printing method.

  Furthermore, as shown in FIG. 11, the protrusion 13 may have a structure in which the porosity increases from the separator substrate side toward the catalyst layer side. Specifically, the porosity of the fourth protrusion 13d in contact with the gas diffusion layer can be made higher than the porosity of the third protrusion 13c on the separator side. With such a configuration, the air permeability changes, so that the gas pressure loss can be reduced and the gas pressure between the separator substrate and the gas diffusion layer can be controlled. Can be supplied uniformly and as a whole. As a method of forming the protrusions as shown in FIG. 11, first, as shown in FIG. 11A, first, the third protrusion 13c having a low porosity is formed by screen printing. Thereafter, as shown in FIG. 11B, the fourth protrusion 13d is formed on the third protrusion 13c by the same screen printing method. Moreover, the porosity can be increased by increasing the particle diameter of the conductive particles contained in the protrusions.

  Furthermore, the protrusion 13 may have a structure in which water repellency increases from the separator base material side toward the catalyst layer side. By adopting such a structure in which the water repellency changes within the protrusion, the generated water that has entered the protrusion can be quickly discharged to the outside of the protrusion, a gas flow path is secured, and power generation performance is improved. The water repellency can be changed by increasing or decreasing the content of a water repellent such as polytetrafluoroethylene (PTFE) that can be contained in the protrusions together with the conductive particles. That is, as in FIG. 11, first, the protrusion on the separator side is formed using a slurry with a small amount of water repellent, and then the protrusion on the catalyst layer side is formed using a slurry with a large amount of water repellent. The PTFE content in the protrusions 13 can be changed within a range of 5 to 40 wt%. Further, a hydrophilic agent such as silica may be added to the separator side of the protrusion to make it hydrophilic.

  The number, arrangement, shape, porosity, and water repellency of the protrusions as described above can be set to be optimal depending on the hydrogen concentration in the fuel gas used, the power generation status, and the like. In particular, regarding the distance between the protrusions, the separator of Patent Document 1 forms the protrusions by press-molding a metal plate, and thus it is difficult to make the distance between the protrusions less than 0.5 mm. Therefore, there has been a problem that sufficient gas diffusibility cannot be obtained and power generation performance is lowered. In addition to the problem that the distance between the protrusions is too large, the protrusion at the central part of the separator has a larger structure, so that gas entry and exhaust into the catalyst layer in the central part of the separator are likely to be hindered, resulting in a decrease in power generation performance. There was a problem. However, in the separator of this embodiment, since the protrusions are made porous and the distance between the protrusions is 500 μm or less, it is possible to form a very fine flow path structure, which is uniform with respect to the gas diffusion layer and the catalyst layer. It is possible to supply gas.

  Moreover, as shown in FIG. 1, the separator of this embodiment may provide the protrusion 13 in one surface of the separator base material 10, and may form the cooling water flow path 8 in the other surface. However, in order to reduce the thickness of the separator, a protrusion 13 for the fuel gas flow path is provided on one surface of the separator base material, and a protrusion 13 for the oxidant gas flow path is provided on the other surface. A cooling water flow path may be formed. In addition, the protrusion 13 of the separator according to the present embodiment may have a rectangular parallelepiped shape as well as a columnar shape and a blunt shape as described above. For example, as shown in FIG. 12, a striped reaction gas is provided so that a plurality of rectangular parallelepiped protrusions 13 are provided on a flat separator substrate so that fuel gas flows from the fuel gas supply manifold 11a to the fuel gas discharge manifold 11b. A flow path may be formed. With this configuration, the fuel gas passes through and diffuses not only in the groove 10a existing between the protrusions 13 but also in the protrusions 13, so that the fuel gas is supplied more uniformly to the entire catalyst layer. can do.

  As the gas diffusion layer used in the fuel cell 1 together with the separator of the present embodiment, known carbon paper or carbon cloth can be used. In order to increase the conductivity of carbon paper or carbon cloth, a conductive material such as carbon particles may be applied, and in order to further improve the water repellency, a water repellent material such as PTFE may be applied. good. Moreover, a well-known platinum carrying | support carbon etc. can be used as a catalyst layer.

  Next, the manufacturing method of the separator of this embodiment is demonstrated. The protrusions of the separator of this embodiment can be formed by screen printing. Specifically, first, a slurry containing conductive particles that are constituents of protrusions and a solvent is formed. As the solvent, an organic solvent such as water or alcohol can be used. In addition to the conductive particles, a surfactant can be added to the slurry in order to enhance the dispersibility of the conductive particles in the solvent. Further, as described above, PTFE may be added to increase the water repellency of the protrusions. Further, a thickener may be added to screen the slurry to improve the viscosity.

  Next, the prepared slurry is applied on the separator substrate using a screen printing device so as to form protrusions. In this case, it is preferable to previously form a supply manifold, a discharge manifold, and the like on the separator base material. A commercially available desktop screen printer can be used as the screen printing apparatus. When forming protrusions as shown in FIGS. 10 and 11, coating is performed a plurality of times using different slurries. After applying the slurry, in order to remove the solvent, it is dried and fired as necessary. Thus, in this embodiment, since the projection can be formed by screen printing, the projection can be easily formed at low cost, and the degree of design freedom can be greatly improved.

  Furthermore, the protrusions can be formed using carbon fibers. Specifically, first, carbon fibers are formed on a separator substrate by a vapor growth method. Thereafter, the slurry containing conductive particles is applied by screen printing so as to cover the carbon fibers. Then, after applying the slurry, in order to remove the solvent, the protrusions can be formed by drying and baking. Thus, by providing the carbon fiber inside the protrusion, the electrical resistance (contact resistance) between the separator substrate and the protrusion can be lowered. Further, since the carbon fiber serves as a skeleton of the protrusion, slack and deformation of the slurry can be prevented, and the protrusion can be easily formed. Furthermore, the robustness of guaranteeing the formation position accuracy of the protrusion is improved, and the performance is improved. In addition, the robustness of the projection coating position accuracy guarantee is improved, and the workability is improved. Note that the volume of the carbon fiber in the protrusion is preferably 50% or less of the volume of the entire protrusion. If the volume of the carbon fiber in the protrusion exceeds 50%, the porosity of the protrusion may be reduced and gas permeability may be reduced.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to these Examples.

(Preparation of slurry A)
Slurry A for forming protrusions was prepared as follows. First, 2 g of a surfactant (manufactured by Dow Chemical Company, Triton X-100) and 200 g of pure water were mixed and stirred for 30 minutes using a propeller stirrer (rotation speed: 150 rpm). Furthermore, 20 g of carbon black (manufactured by Cabot Corporation, Vulcan XC-72R) was added to the surfactant-dispersed aqueous solution, and the mixture was stirred for 60 minutes using a propeller stirring device (rotation speed: 150 rpm). Next, 8 g of polytetrafluoroethylene (manufactured by Daikin Industries, Ltd., Polyflon D-1E) and a thickener were added to the slurry in an appropriate amount, followed by stirring to prepare slurry A for protrusions.

(Preparation of slurry B)
Next, slurry B for forming a gas diffusion layer provided on the protrusions was prepared as follows. First, 2 g of a surfactant (manufactured by Dow Chemical Company, Triton X-100) and 200 g of pure water were mixed and stirred for 30 minutes using a propeller stirrer (rotation speed: 150 rpm). Furthermore, 20 g of carbon black (manufactured by Cabot Corporation, Vulcan XC-72R) was added to the surfactant-dispersed aqueous solution, and the mixture was stirred for 30 minutes using a propeller stirring device (rotation speed: 150 rpm) to prepare a slurry. Next, the slurry was pulverized using a jet mill, and the average particle size of the carbon black was set to 1 μm. Thereafter, 8 g of polytetrafluoroethylene (manufactured by Daikin Industries, Ltd., Polyflon D-1E) and a thickener were added to the slurry in an appropriate amount, followed by stirring to prepare slurry B for protrusions.

(Slurry A coating)
First, a plate-shaped metal separator substrate on which a manifold for introducing and discharging reaction gas was formed in advance was prepared. Next, the separator base material was set at a predetermined position of the screen printing apparatus. Thereafter, slurry A was applied onto the separator substrate using a screen on which a predetermined protrusion pattern was formed so that the coating range was 55 mm × 55 mm, thereby forming a protrusion precursor. Next, the separator substrate on which the protrusion precursor was formed was naturally dried at room temperature for 60 minutes, and then subjected to a drying treatment at 80 ° C. for 15 minutes. Furthermore, after performing the same coating and drying treatment several times, a baking treatment at 350 ° C. for 30 minutes is performed, and as shown in FIG. 13A, a circle having a diameter of about 0.2 mm and a height of 150 μm. A plurality of columnar protrusions were formed. The diameter and height of the protrusions were measured with a digital fine scope (manufactured by OMRON Corporation, 3D digital fine scope VC3500 type).

(Slurry B coating)
First, as shown in FIG. 13 (b), a masking 20 was formed around the above-described separator substrate 10 with protrusions. Next, as shown in FIG. 13 (c), using the knife coater (coating apparatus: RK Print Coat Instruments Ltd., Control Coater manufactured by KK, knife unit: film applicator manufactured by Tester Sangyo Co., Ltd.) Slurry B was applied on the masking 20. Further, the separator base material 10 coated with the slurry B was naturally dried at room temperature for 60 minutes, and then the masking 20 was removed. Then, the separator base material from which the masking 20 was removed was subjected to a drying treatment at 80 ° C. for 15 minutes and a baking treatment at 350 ° C. for 30 minutes. In this way, as shown in FIG. 13 (d), a gas diffusion electrode having a height of 180 μm was formed together with the protrusion 13 and the gas diffusion layer 21.

  As mentioned above, although this invention was demonstrated with some embodiment and an Example, this invention is not limited to these, A various deformation | transformation is possible within the range of the summary of this invention. The separator of the present invention has been described mainly based on the combustion electrode separator so far, but the air electrode separator can also have a similar configuration including a separator substrate and protrusions. Further, in the present specification and claims, fuel gas and oxidant gas are collectively referred to as reaction gas.

FIG. 1 is a cross-sectional view showing an example of a fuel cell (single cell) provided with a separator according to an embodiment of the present invention, (a) is a diagram showing the entire fuel cell, and (b) is a partially enlarged view. It is. FIG. 2 is a perspective view showing an embodiment of a separator according to the present invention. FIG. 3 is a plan view for explaining the arrangement of the protrusions in the separator according to the embodiment of the present invention. FIG. 4 is a plan view for explaining the arrangement of protrusions in the separator according to the embodiment of the present invention. FIG. 5 is a plan view for explaining the arrangement of protrusions in the separator according to the embodiment of the present invention. FIG. 6 is a plan view for explaining the arrangement of protrusions in the separator according to the embodiment of the present invention. FIG. 7 is a plan view for explaining the arrangement of protrusions in the separator according to the embodiment of the present invention. FIG. 8 is a plan view for explaining the cross-sectional shape of the protrusion. FIG. 9 is a schematic view showing a convex portion provided on the surface of the protrusion. FIG. 10 is a side view for explaining the shape of the protrusion. FIG. 11 is a side view for explaining the difference in the porosity of the protrusions. FIG. 12 is a perspective view showing another embodiment of the separator according to the present invention. FIG. 13 is a cross-sectional view illustrating a method for manufacturing a separator according to an example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel cell 2 Solid polymer electrolyte membrane 3 Air electrode 4 Fuel electrode 5 Membrane electrode assembly 6 Air electrode separator 7 Fuel electrode separator 8 Cooling water flow path 10 Separator base material 13 Protrusion 14 Protrusion F Fuel gas flow direction

Claims (10)

A separator substrate;
Provided on the separator substrate, forming a reaction gas flow path on the surface of the separator substrate, and a plurality of protrusions made of a porous body;
With
The protrusion contains conductive particles having a particle diameter of 0.5 μm to 50 μm, and the protrusion has a porosity of 65 to 90%.
The plurality of protrusions are provided in a staggered manner with respect to the reaction gas flow direction,
A straight line connecting the centers of two protrusions adjacent to each other along the reaction gas flow direction, and a surface perpendicular to the surface of the protrusion formed on the upstream side of the reaction gas in the two protrusions , and in the reaction gas flow direction A fuel cell separator characterized in that an angle formed by parallel gas flow lines is 0 to 50 °. A separator substrate;
Provided on the separator substrate, forming a reaction gas flow path on the surface of the separator substrate, and a plurality of protrusions made of a porous body;
With
Said projection has a particle size containing conductive particles of 0.5 to 50 .mu.m, Ri further porosity of the protrusions 65 to 90% der,
In the cross section of the protrusion, the length in the direction orthogonal to the reaction gas flow direction is longer than the length in the reaction gas flow direction . The protrusion has a cylindrical shape, and the cross-sectional diameter of the protrusion is 65 μm to 500 μm.
2. The fuel cell separator according to claim 1, wherein a distance between the adjacent protrusions is 150 μm to 1000 μm. The fuel cell separator according to any one of claims 1 to 3 , wherein a plurality of protrusions are formed on a surface of the protrusion. The separator is provided on one surface of the catalyst layer,
The projections, the fuel cell separator according to any one of claims 1 to 4, characterized in that widens toward from the separator base material side to the catalyst layer side. The separator is provided on one surface of the catalyst layer,
The porosity of the protrusions, the fuel cell separator according to any one of claims 1 to 5, wherein the higher of Turkey toward the catalyst layer side from the separator base material side. The fuel cell separator according to any one of claims 1 to 6 , wherein the projection has a plurality of pores, and the pore diameter of the pores is 0.1 µm to 10 µm. The separator is provided on one surface of the catalyst layer,
The water repellency of the protrusions, the fuel cell separator according to any one of claims 1 to 7, characterized and Turkey a higher toward the catalyst layer side from the separator base material side. A fuel cell separator according to any one of claims 1 to 8 ,
A membrane electrode assembly including an electrolyte membrane and a catalyst layer;
A fuel cell comprising: A method for producing a fuel cell separator according to any one of claims 1 to 9,
Preparing a slurry containing conductive particles;
A step of forming a projection precursor by coating the slurry on a separator substrate by screen printing;
A step of forming protrusions by drying the separator substrate coated with the slurry;
The manufacturing method of the separator for fuel cells characterized by having.

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