JP2005339846A - Separator for fuel cell, fuel cell provided with it, and manufacturing method of separator for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator for a fuel cell capable of exhausting water drops generated in a gas passage and enhancing corrosion resistance, a fuel cell provided with this separator and a manufacturing method of the separator. <P>SOLUTION: The separator 18 for the fuel cell has the gas passage 30 demarcated by recessed parts of a continuous projecting and recessed part and an electrode contact surface 31 in which the peak surface of the projecting part comes in contact with an electrode, at least a part on the surface of the gas passage 30 is hydrophilic, and the electrode contact surface is hydrophobic. The manufacturing method of the separator 18 has a process giving hydrophilic property to at least a part of the surface of the gas passage 30 and a process giving hydrophobic property to the electrode contact surface 31. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell separator, a fuel cell including the same, and a method for manufacturing the fuel cell separator, and in particular, a fuel cell separator having a gas flow path defined by an uneven shape and the same. The present invention also relates to a fuel cell and a method for manufacturing the fuel cell separator.

  Conventionally, a general polymer electrolyte fuel cell includes an electrolyte membrane composed of an ion exchange membrane, a fuel electrode (anode electrode) composed of a catalyst layer and a diffusion layer disposed on one surface of the electrolyte membrane, and the electrolyte membrane. An oxidant electrode (cathode electrode) composed of a catalyst layer and a diffusion layer disposed on the other surface of the membrane, a membrane-electrode assembly (MEA) consisting of the MEA, and the MEA There is a type in which a cell including a separator disposed on each side is formed and a plurality of such cells are stacked to form a module.

  As the separator, there is a separator in which a concavo-convex shape is formed on the surface facing the MEA, a convex portion is in contact with the electrode, and the concave portion is a gas flow path for circulating gas. That is, the separator disposed on the fuel electrode side supplies a fuel gas to the fuel electrode by flowing a fuel gas (for example, hydrogen) through the gas flow path, and the top surface of the convex portion is the fuel electrode. The separator disposed in contact with the oxidant electrode side circulates an oxidant gas (oxygen, usually air) through the gas flow path to supply the oxidant gas to the oxidant electrode, and at the top of the convex portion. The surface is in contact with the oxidizer electrode.

  In such a fuel cell, if the entire surface of the wall part defining the gas flow path of the separator is water-repellent, water droplets generated in the gas flow path may become, for example, spherical and block the gas flow path. There is a possibility that it is difficult to efficiently discharge water droplets to the outside. In view of this, there has been proposed a fuel cell capable of efficiently discharging water droplets generated in the gas flow path to the outside in the separator of the fuel cell and allowing the reaction gas to flow stably and uniformly.

  As such a conventional fuel cell capable of stably and uniformly circulating the reaction gas, for example, a separator is coated with a hydrophilic material containing titanium on the surface of the separator and heat-treated in an oxygen atmosphere. There is a film in which a titanium oxide film (hydrophilic film) is formed and then the titanium oxide film formed on the contact portion of the separator, that is, the electrode contact surface is removed to expose the titanium surface. (For example, refer to Patent Document 1).

Various conventional techniques for forming a hydrophilic film on the surface of a metal separator have also been proposed. (For example, see Patent Documents 2, 3, 4, and 5). Furthermore, various conventional techniques for forming a water repellent film on the surface of a metal separator have been proposed. (For example, refer to Patent Documents 6 and 7).
JP 2001-93539 A JP 2001-325966 A JP 2002-20690 A JP 2002-25570 A WO99 / 40642 JP 2000-1000045 A JP 2003-142120 A

  However, in the fuel cell described in Patent Document 1 described above, since the surface of the gas flow path of the separator is hydrophilic, water droplets generated in the gas flow path can be efficiently discharged to the outside. Since the hydrophilic film remains on the electrode contact surface, water exists in this portion, and the electrode contact surface of the separator may be easily corroded by a chemical reaction with water. In particular, the electrode contact surface of the separator is in the most severe corrosive environment in the gas flow path. If water is present in this portion, the metal constituting the separator may corrode.

  Moreover, in the prior art described in Patent Documents 1 to 7, the gas flow path (concave part) and the electrode contact surface (convex part) of the separator are divided into hydrophilicity and water repellency, respectively. There is no description of a technique that can efficiently discharge water droplets generated outside to the outside and improve corrosion resistance.

  An object of the present invention is to improve such a conventional fuel cell separator, and can efficiently discharge water droplets generated in a gas flow path to the outside and improve corrosion resistance. An object of the present invention is to provide a possible fuel cell separator, a fuel cell including the separator, and a method of manufacturing the separator.

  In order to achieve this object, the present invention provides a fuel cell separator having a gas flow path defined by continuous concave and convex concave portions and an electrode contact surface in which the top surface of the convex portions contacts the electrode. In the fuel cell separator, at least a part of the surface (outermost surface) of the gas flow path is hydrophilic and the electrode contact surface is water repellent.

  Since the fuel cell separator having this configuration has a water-repellent electrode contact surface, water generated on the electrode contact surface can be efficiently moved to the gas flow path. For this reason, water can be prevented from staying on the electrode contact surface of the separator, and corrosion of the electrode contact surface can be prevented. Moreover, since at least a part of the surface of the gas channel is hydrophilic, water present in the gas channel can be efficiently discharged to the outside.

  Moreover, in the fuel cell separator according to the present invention, at least the lowermost region of the surface of the gas flow path with respect to the direction of gravity can be made hydrophilic. By comprising in this way, the water which exists in the said gas flow path can be discharged | emitted more efficiently outside.

  In the fuel cell separator according to the present invention, the entire surface of the gas flow path may be hydrophilic. By doing in this way, the water which exists in the said gas flow path can be discharged | emitted more efficiently outside.

  Further, the present invention provides the separator for a fuel cell according to the present invention described above on both sides of a membrane-electrode assembly including an electrolyte membrane and a pair of electrodes formed on both sides of the electrolyte membrane. The present invention provides a fuel cell disposed in contact with each electrode.

  Since the fuel cell having this configuration includes the fuel cell separator according to the present invention described above, the water present in the gas flow path can be efficiently discharged to the outside.

  Furthermore, the present invention is a method of manufacturing a fuel cell separator having a gas flow path defined by continuous concave and convex concave portions and an electrode contact surface in which the top surface of the convex portions contacts the electrode. A method for producing a fuel cell separator, comprising: imparting hydrophilicity to at least a part of the surface (outermost surface) of the gas flow path; and imparting water repellency to the electrode contact surface. Is to provide.

  According to this manufacturing method, it is possible to manufacture a fuel cell separator in which the electrode contact surface is water-repellent and at least a part of the surface of the gas channel is hydrophilic. Therefore, the water produced | generated on the electrode contact surface can be efficiently moved to a gas flow path, and it can prevent that water stays on the electrode contact surface of a separator. For this reason, it can prevent that an electrode contact surface corrodes. Moreover, since at least a part of the surface of the gas channel is hydrophilic, water present in the gas channel can be efficiently discharged to the outside.

  The method for producing a separator for a fuel cell according to the present invention includes a step of forming a water repellent layer on the surface of the gas channel and a region serving as an electrode contact surface, and forming a hydrophilic layer on the water repellent layer. A step and a step of removing the hydrophilic layer formed in the region to be the electrode contact surface. By performing these steps, it is possible to easily obtain a separator in which the surface of the gas channel is hydrophilic and the electrode contact surface is water repellent.

  Examples of the water repellent layer include a coating film mainly composed of carbon.

  The method for producing a separator for a fuel cell according to the present invention includes a step of forming a hydrophilic layer on the surface of the gas flow path and a region to be an electrode contact surface, and after forming the hydrophilic layer, the electrode And a step of forming a water repellent layer on the hydrophilic layer formed in the region to be the contact surface. By performing these steps, it is possible to easily obtain a separator in which the surface of the gas channel is hydrophilic and the electrode contact surface is water repellent. In this case, it is desirable that the hydrophilic layer has corrosion resistance. Or before forming the said hydrophilic layer, it is desirable to further provide the process of forming a corrosion-resistant layer in the area | region used as the surface of the said gas flow path, and an electrode contact surface.

  The hydrophilic layer can be formed by plasma treatment. Here, the plasma treatment has characteristics such as imparting a functional group (for example, OH group) to the material to be treated, roughening the surface, and removing attached organic contaminants. . Therefore, since the hydrophilic layer formed by the plasma treatment has a roughened surface, for example, the adhesive force with the seal part of the fuel cell can be improved, and the reliability of the seal can be improved. Moreover, contact resistance can also be reduced.

  Furthermore, the method for producing a separator for a fuel cell according to the present invention includes a step of forming a water repellent layer on the surface of the gas flow path and the area that becomes the electrode contact surface, and at least the area that becomes the surface of the gas flow path. And a step of forming a hydrophilic layer by injection molding in part. Also by these steps, a separator in which the surface of the gas channel is hydrophilic and the electrode contact surface is water repellent can be easily obtained.

  The method for producing a separator for a fuel cell according to the present invention includes a step of forming a water repellent layer on the surface of the gas flow path and the area that becomes the electrode contact surface, and at least the area that becomes the surface of the gas flow path. And a step of performing a plasma treatment on a part thereof. Also by these steps, a separator in which the surface of the gas channel is hydrophilic and the electrode contact surface is water repellent can be easily obtained. In the case of this manufacturing method, since the hydrophilic layer is formed by plasma treatment, the surface of the hydrophilic layer is roughened, for example, improving the adhesive force with the seal portion of the fuel cell and improving the reliability of the seal. It can also be improved. Moreover, contact resistance can also be reduced.

  In the case of this manufacturing method, after forming the water-repellent layer, a step of forming a mask on the water-repellent layer formed in the region serving as the electrode contact surface, and with the mask being formed, A step of selectively plasma-treating the aqueous layer, and a step of removing the mask after the plasma treatment.

  According to this manufacturing method, the region serving as the electrode contact surface is not subjected to plasma treatment due to the presence of a mask, so that water repellency can be maintained, and the surface of the gas flow path is subjected to plasma treatment. The surface of the gas channel can be made hydrophilic. Further, since the plasma treatment is performed on the region where the mask is not formed, for example, the plasma treatment is also performed on the edge portion of the separator (for example, the portion bonded to the seal portion), and this portion is roughened. It can also be surfaced. For this reason, the adhesive force with the seal part of the fuel cell can be improved, and the reliability of the seal can be improved. Moreover, contact resistance can also be reduced.

  Further, the method for producing a fuel cell according to the present invention comprises forming a water repellent layer on the surface of the gas flow path and the region that becomes the electrode contact surface, and then on the water repellent layer formed on the region that becomes the electrode contact surface. A step of forming a layer made of an organic material, and a step of selectively plasma-treating the water-repellent layer in a state where the layer made of the organic material is formed.

  According to this manufacturing method, since the layer made of an organic material functions as a mask in the region serving as the electrode contact surface, plasma treatment is not performed, so that water repellency can be maintained. In addition, since the plasma treatment is performed on the region that becomes the surface of the gas flow path, the surface of the gas flow path can be made hydrophilic.

  Here, since the layer made of the organic material is removed by the plasma treatment, the plasma treatment is preferably terminated at the timing when all the layers made of the organic material are removed. Thus, the plasma processing time can be controlled according to the thickness of the layer made of an organic material. In addition, since the plasma treatment is performed on the region where the layer made of the organic material is not formed, for example, the plasma treatment is also performed on the edge portion of the separator, and this portion can be roughened. For this reason, the adhesive force with the seal part of the fuel cell can be improved, and the reliability of the seal can be improved.

  Further, in the step of performing the plasma treatment on the gas flow path, in addition to using a mask or a layer made of an organic material as described above, for example, a torch type plasma processing apparatus having a size corresponding to the shape of the gas flow path, etc. May be used.

  The “surface” in the present invention means the uppermost surface (that is, the exposed surface). The “electrode contact surface” means a “surface” in contact with the electrode of the MEA.

  According to the fuel cell separator of the present invention, since at least a part of the surface of the gas channel is hydrophilic and the electrode contact surface is water repellent, water is prevented from remaining on the electrode contact surface of the separator. In addition, the water existing in the gas flow path can be efficiently discharged to the outside. For this reason, it can prevent that an electrode contact surface corrodes, and can prevent that water accumulates on a gas channel surface. As a result, when the fuel cell separator according to the present invention is used in a fuel cell, the performance of the fuel cell can be improved.

  In addition, since the fuel cell according to the present invention includes a separator in which at least a part of the surface of the gas flow path is hydrophilic and the electrode contact surface is water repellent, water remains on the electrode contact surface of the separator. Can be prevented, and water existing in the gas flow path can be efficiently discharged to the outside. As a result, corrosion of the electrode contact surface can be prevented, and water can be prevented from accumulating on the gas flow path surface, and the performance of the fuel cell can be improved.

  Furthermore, according to the fuel cell manufacturing method of the present invention, it is possible to easily manufacture a separator in which at least a part of the surface of the gas flow path is hydrophilic and the electrode contact surface is water repellent.

  Next, a fuel cell separator according to an embodiment of the present invention, a fuel cell including the fuel cell separator, and a method for manufacturing the fuel cell separator will be described with reference to the drawings. In addition, the Example described below is the illustration for demonstrating this invention, and this invention is not limited only to these embodiment. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  1 is an overall schematic diagram of a fuel cell according to Example 1 of the present invention, FIG. 2 is a cross-sectional view of a single cell constituting the fuel cell shown in FIG. 1, and FIG. 3 is a diagram of one unit cell shown in FIG. FIG. 4 is a sectional view showing a manufacturing process of a metal separator that is a component of the fuel cell according to the first embodiment.

  As shown in FIGS. 1 to 4, a fuel cell 1 according to Example 1 includes an electrolyte membrane 11 made of an ion exchange membrane, and a fuel electrode 14 made of a catalyst layer and a diffusion layer disposed on one surface of the electrolyte membrane 11 ( Anode) and a membrane-electrode assembly (MEA) 10 composed of an oxidant electrode 17 (cathode) composed of a catalyst layer and a diffusion layer disposed on the other surface of the electrolyte membrane 11, and the fuel electrode 14 side and the oxidation across the MEA 10 A single cell 40 is formed by overlapping the metal separators 18 respectively disposed on the agent electrode 17 side. One or more single cells 40 are stacked to form a module 9 (in Example 1, one module is formed from one cell), and a plurality of modules 9 are stacked to form a module group. Reference numeral 12 denotes a seal portion, reference numeral 13A denotes a fuel gas supply manifold, reference numeral 13B denotes a fuel gas discharge manifold, reference numeral 15A denotes an oxidizing gas supply manifold, and reference numeral 15B denotes an oxidizing gas discharge manifold.

  A terminal 20, an insulator 21, and an end plate 22 are disposed at both ends of the module group in the cell stacking direction, and a stack 23 is configured by the module group. The stack 23 is fixed by a fastening member 24 (for example, a tension plate, a through bolt, etc.) that extends in the cell stacking direction on the outside, and a bolt 25 or a nut, and is tightened in the cell stacking direction to form the fuel cell 1.

  As shown in FIGS. 2 to 4, the metal separator 18 has a continuous concavo-convex shape, and has a gas flow path 30 defined by the concave portion, and the top surface of the convex portion is an electrode (fuel electrode). 14 or the oxidant electrode 17 and the oxidant electrode 17 in FIG. 3). A coolant channel 32 through which a coolant such as cooling water flows is formed on the surface of the metal separator 18 opposite to the side where the gas channel 30 and the electrode contact surface 31 are formed.

  A hydrophilic layer 35 is formed in a region that becomes the surface (bottom surface and standing surface) of the gas flow path 30, and a water repellent layer 37 is formed in a region that becomes the electrode contact surface 31. For this reason, while being able to move the water produced | generated on the electrode contact surface 31 to the gas flow path 30 efficiently, the water which exists in the gas flow path 30 can be discharged | emitted efficiently outside. Therefore, it is possible to prevent water from remaining on the electrode contact surface 31 of the metal separator 18, to prevent the electrode contact surface 31 from corroding, and to prevent water from stagnating in the gas flow path 30. can do. As a result, the performance of the fuel cell 1 can be improved.

  Examples of the water repellent layer 37 include a coating film mainly composed of carbon.

  This metal separator 18 can be manufactured, for example, by the steps shown in FIGS. That is, in the process shown in FIG. 4A, a desired metal plate is pressed to form a metal separator body 38 having a continuous uneven shape.

  Next, in the step shown in FIG. 4 (2), a material having water repellency (for example, a paint made of a corrosion-resistant material having conductivity) is applied to the surface of the metal separator main body 38, and the water-repellent layer. 37 is formed.

  Next, in the step shown in FIG. 4 (3), a hydrophilic resin is applied to the surface of the water repellent layer 37 by, for example, spraying or dipping, etc., to form the hydrophilic layer 35.

  Next, in the step shown in FIG. 4 (4), the resin applied to the region to be the electrode contact surface 31 is dried before the hydrophilic resin applied in the step shown in FIG. 4 (3) is dried. For example, it is removed by a roller. In this way, the hydrophilic layer 35 is formed in the region that becomes the surface (bottom surface and standing surface) of the gas flow path 30, and the water repellent layer 37 is formed in the region that becomes the electrode contact surface 31. The Through the above steps, the metal separator 18 in which the surface of the gas flow path 30 is hydrophilic and the electrode contact surface 31 is water repellent was manufactured.

  Next, a fuel cell separator according to a second embodiment of the present invention, a fuel cell including the fuel cell separator, and a method of manufacturing the fuel cell separator will be described with reference to the drawings.

  FIG. 5 is a partially enlarged cross-sectional view of a single cell constituting the fuel cell according to the second embodiment, and FIG. 6 is a cross section showing a part of a manufacturing process of a metal separator that is a component of the fuel cell according to the second embodiment. FIG. In the second embodiment, the members described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 5 and 6, the metal separator 18 according to Example 2 has a hydrophilic layer 35 formed in a region that becomes the surface (bottom surface and standing surface) of the gas flow path 30, and the electrode contact surface. A water repellent layer 39 is formed in the region 31. Specifically, a water repellent layer 37 and a hydrophilic layer 35 are sequentially formed on the metal separator main body 38, and a water repellent layer 39 is further formed in a region that becomes the electrode contact surface 31.

  Similarly to the first embodiment, the metal separator 18 having this configuration can efficiently move the water generated on the electrode contact surface 31 to the gas flow path 30 and also remove the water existing in the gas flow path 30 to the outside. It can be discharged efficiently. For this reason, it is possible to prevent water from remaining on the electrode contact surface 31 of the metal separator 18, to prevent the electrode contact surface 31 from corroding, and to prevent water from collecting in the gas flow path 30. can do. As a result, the performance of the fuel cell 1 can be improved.

  The metal separator 18 can be manufactured, for example, by the steps shown in FIGS. 6 (1) and (2). That is, in the step shown in FIG. 6A, the same steps as the steps shown in FIGS. 4A to 4C are performed.

  Next, in the step shown in FIG. 6 (2), a material having water repellency (for example, conductive resistance resistance) is formed on the region to be the electrode contact surface 31 of the hydrophilic layer 35 by, for example, roller printing. A water-repellent layer 39 is formed by applying a paint made of a corrosive material. In this way, the hydrophilic layer 35 is formed in the region that becomes the surface (bottom surface and standing surface) of the gas flow path 30, and the water repellent layer 39 is formed in the region that becomes the electrode contact surface 31. A metal separator 18 is obtained. Through the above steps, the metal separator 18 in which the surface of the gas flow path 30 is hydrophilic and the electrode contact surface 31 is water repellent was manufactured.

  The hydrophilic layer 35 can also be formed by subjecting the water repellent layer 37 to plasma treatment. In this case, since the surface subjected to the plasma treatment is roughened, if the edge of the metal separator 18 is also subjected to the plasma treatment, the portion bonded to the seal portion 12 of the fuel cell can be roughened. Therefore, the adhesiveness between the metal separator 18 and the seal portion 12 can be improved, and the reliability of the seal can be improved.

  In Example 2, the water-repellent layer 37 mainly functions as a layer for imparting corrosion resistance. If the hydrophilic layer 35 having corrosion resistance is employed, the water-repellent layer 37 is not necessarily provided. May be.

  Next, a fuel cell separator according to a third embodiment of the present invention, a fuel cell including the fuel cell separator, and a method for manufacturing the fuel cell separator will be described with reference to the drawings.

  FIG. 7 is a partially enlarged cross-sectional view of a single cell constituting the fuel cell according to the third embodiment. FIG. 8 is a cross section showing a part of a manufacturing process of a metal separator that is a component of the fuel cell according to the third embodiment. FIG. In Example 3, members described in Examples 1 and 2 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIGS. 7 and 8, the metal separator 18 according to Example 3 has a hydrophilic layer 35 formed in a region that becomes the surface (bottom surface and standing surface) of the gas flow path 30, and the electrode contact surface. A water repellent layer 37 is formed in the region 31. Specifically, the water-repellent layer 37 is not formed in the region that is the surface of the gas flow path 30 on the metal separator main body 38, and the hydrophilic layer 35 is formed directly on the metal separator main body 38. A water repellent layer 37 is directly formed in the region that becomes the electrode contact surface 31. In Example 3, the hydrophilic layer 35 was formed from a resin or the like having corrosion resistance.

  The metal separator 18 can be manufactured by, for example, the steps shown in FIGS. That is, in the process shown in FIG. 8 (1), a mold is formed on the surface of the metal separator body 38 used in the process shown in FIG. 4 (1) on the side where the gas flow path 30 and the electrode contact surface 31 are formed. Wear 100. The mold 100 is configured such that a predetermined space 101 is formed between the metal separator main body 38 and a region serving as the surface of the gas flow path 30.

  Next, in the step shown in FIG. 8 (2), the hydrophilic resin 35A having corrosion resistance is heated and melted by a device (not shown) and pressurized and injected into the space 101 of the mold 100 by a plunger or screw (not shown), or Fill with pressure. Then, after the resin 35A is solidified or cured, the mold 100 is removed. Thus, the hydrophilic layer 35 was formed by injection molding using the mold 100.

  Next, in the step shown in FIG. 8 (3), a material having water repellency (for example, corrosion resistance having conductivity) is formed on the region to be the electrode contact surface 31 of the metal separator body 38 by, for example, a roller printing method. A water-repellent layer 37 is formed by applying a coating material made of a functional material such as carbon). In this way, the hydrophilic layer 35 is formed in the region that becomes the surface (bottom surface and standing surface) of the gas flow path 30, and the water-repellent layer 37 is formed in the region that becomes the electrode contact surface 31. A metal separator 18 is obtained. Through the above steps, the metal separator 18 in which the surface of the gas flow path 30 is hydrophilic and the electrode contact surface 31 is water repellent was manufactured.

  In the metal separator 18 having this configuration, since the hydrophilic layer 35 has corrosion resistance, it is not necessary to separately provide a layer for imparting corrosion resistance on the metal separator body 38. Therefore, material costs can be saved.

  Further, after forming the water repellent layer 35 as a layer for imparting corrosion resistance on the metal separator 18, the metal separator 18 having the structure shown in FIG. 3 can be obtained by performing the steps shown in FIGS. Can also be manufactured.

  Further, as shown in FIG. 9, if a mold 100 configured so that a predetermined space 102 is formed between the metal separator main body 38 and the region serving as the bottom surface of the gas flow path 30 is used, FIG. As shown in FIG. 5, the hydrophilic layer 35 can be formed only in the region that becomes the bottom surface of the gas flow path 30.

  Furthermore, if a mold configured to form a predetermined space between the metal separator main body 38 and the region serving as the standing surface (side wall) of the gas flow path 30 is used, a portion corresponding to the space is used. A hydrophilic layer can be formed.

  As described above, in the method of forming the hydrophilic layer by injection molding using a mold, for example, when the fuel cell 1 in which the metal separator 18 is incorporated is mounted on a vehicle body or the like, A hydrophilic layer can be easily formed at a position corresponding to the lower end.

  Further, a hydrophilic layer is formed on the metal separator main body 38, and thereafter a mold configured to form a predetermined space between the metal separator main body 38 and the region that becomes the electrode contact surface 31 is used. The space may be filled with a material having water repellency. According to this method, for example, the metal separator 18 having the structure shown in FIGS.

  Next, the manufacturing method of the separator for fuel cells concerning Example 4 of the present invention is explained with reference to drawings.

  FIG. 11 is a cross-sectional view illustrating a part of the manufacturing process of the metal separator that is a component of the fuel cell according to the fourth embodiment. In Example 4, members described in Examples 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the step shown in FIG. 11 (1), the same step as that shown in FIGS. 4 (1) and (2) is performed to form the water repellent layer 37 on the metal separator body 38.

  Next, in the step shown in FIG. 11B, a mask 200 is formed in a region that becomes the electrode contact surface 31 of the water repellent layer 37 formed on the metal separator main body 38, and in this state, a plasma treatment is selectively performed. I do.

  Next, in the step shown in FIG. 11C, after the plasma treatment is completed, the mask 200 is removed. In this manner, a region where the plasma treatment was performed, that is, a region serving as the surface of the gas flow path 30, and a metal separator and a water repellent layer 37 that contacted the seal portion 12 (see FIG. 2) were formed. Through the above steps, the metal separator 18 in which the surface of the gas flow path 30 is hydrophilic and the electrode contact surface 31 is water repellent was manufactured. Also in this case, as described above, since the surface of the hydrophilic layer 35 formed by the plasma treatment is roughened, the adhesion between the fuel cell seal portion 12 and the metal separator 18 is improved, and the seal reliability is improved. Can be improved.

  In addition, although Example 4 demonstrated the case where the mask 200 was formed in the area | region used as the electrode contact surface 31 of the water repellent layer 37, it does not restrict to this but forms the layer which consists of organic materials instead of the mask 200 However, the plasma treatment may be selectively performed using this as a mask. In this case, since the layer made of an organic material is removed by plasma treatment, it is not necessary to separately perform a mask removal process. Further, since the plasma treatment can be terminated at the timing when all the layers made of the organic material are removed, the plasma treatment time can be controlled according to the film thickness of the layer made of the organic material.

  Further, as shown in FIG. 12, the surface of the gas flow path 30 of the water repellent layer 37 formed in the step shown in FIG. 11 (1) is formed without forming the mask 200, the layer made of an organic material, or the like. Plasma treatment is performed in a region using a torch type plasma processing apparatus 300 having a size corresponding to the shape of the gas flow path 30, and a hydrophilic layer 35 is formed in a region that becomes the surface of the gas flow path 30. The metal separator 18 having the water repellent layer 37 formed on the contact surface 31 can also be obtained.

  In Examples 1 to 4, the entire surface (bottom surface and standing surface) of the gas flow path 30 is hydrophilic (that is, the hydrophilic layer 35 is formed in the region that is the entire surface of the gas flow path 30). However, the present invention is not limited to this, and it is sufficient that at least a part of the surface of the gas flow path 30 is hydrophilic. In this case, it is more preferable from the viewpoint of water discharge efficiency that the position of the gas flow path 30 that is at least the lower end corresponding to the direction of gravity is hydrophilic.

  In addition, a layer (coating film) having two functions of corrosion resistance and conductivity is required to be formed on the gas flow path surface side (the side opposite to the cooling flow path) of the metal separator 18. When selecting the material of the layer 35 and the water-repellent layers 37 and 39, it is not necessary for each layer to have both corrosion resistance and conductivity, and each layer only needs to have conductivity. Therefore, the corrosion resistance function may be provided in at least one of the hydrophilic layer 35 and the water repellent layers 37 and 39.

  Moreover, although Example 1-Example 4 demonstrated the case where the metal separator 18 was arrange | positioned at the oxidant electrode 17 side, it is the same also when arrange | positioned at the fuel electrode 14 side.

1 is an overall schematic diagram of a fuel cell according to Example 1 of the present invention. It is sectional drawing of the single cell which comprises the fuel cell shown in FIG. It is a partial expanded sectional view of the single cell shown in FIG. It is sectional drawing which shows the manufacturing process of the metal separator which is a component of the fuel cell concerning Example 1 of this invention. It is a partial expanded sectional view of the single cell which comprises the fuel cell concerning Example 2 of this invention. It is sectional drawing which shows a part of manufacturing process of the metal separator which is a component of the fuel cell concerning Example 2 of this invention. It is a partially expanded sectional view of the single cell which comprises the fuel cell concerning Example 3 of this invention. It is sectional drawing which shows a part of manufacturing process of the metal separator which is a component of the fuel cell concerning Example 3 of this invention. It is sectional drawing which shows a part of manufacturing process of the metal separator which is a component of the fuel cell concerning the other Example of this invention. It is a partially expanded sectional view of the separator which comprises the fuel cell concerning the other Example of this invention. It is sectional drawing which shows a part of manufacturing process of the metal separator which is a component of the fuel cell concerning Example 4 of this invention. It is sectional drawing which shows a part of manufacturing process of the metal separator which is a component of the fuel cell concerning the other Example of this invention.

Explanation of symbols

1 Fuel cell 10 MEA
14 Fuel electrode 17 Oxidant electrode 18 Metal separator 30 Gas flow path 31 Electrode contact surface 32 Refrigerant flow path 35 Hydrophilic layer 37, 39 Water-repellent layer 38 Metal separator main body 100 Mold 101, 102 Space 200 Mask 300 Torch type plasma treatment apparatus

Claims (15)

A fuel cell separator having a gas flow path defined by continuous concave and convex portions, and having a top surface of the convex portion constituting an electrode contact surface that contacts the electrode,
A separator for a fuel cell, wherein at least a part of a surface of the gas flow path is hydrophilic and the electrode contact surface is water repellent.   2. The fuel cell separator according to claim 1, wherein at least a lowermost region of the surface of the gas flow path in the direction of gravity is hydrophilic.   The fuel cell separator according to claim 1 or 2, wherein the entire surface of the gas flow path is hydrophilic.   The separator for a fuel cell according to any one of claims 1 to 3, on both sides of a membrane-electrode assembly including an electrolyte membrane and a pair of electrodes formed on both surfaces of the electrolyte membrane. A fuel cell disposed in contact with each of the pair of electrodes. A method for producing a fuel cell separator having a gas flow path defined by a continuous concave-convex concave portion and an electrode contact surface in which the top surface of the convex portion contacts the electrode,
Imparting hydrophilicity to at least part of the surface of the gas flow path;
Providing water repellency to the electrode contact surface;
The manufacturing method of the separator for fuel cells provided with. Forming a water repellent layer in a region to be a surface of the gas flow path and an electrode contact surface;
Forming a hydrophilic layer on the water repellent layer;
Removing the hydrophilic layer formed in the region to be the electrode contact surface;
A method for producing a fuel cell separator according to claim 5. Forming a hydrophilic layer in a region to be a surface of the gas flow path and an electrode contact surface;
After forming the hydrophilic layer, forming a water-repellent layer on the hydrophilic layer formed in the region to be the electrode contact surface;
A method for producing a fuel cell separator according to claim 5.   The method for producing a separator for a fuel cell according to claim 7, wherein the hydrophilic layer has corrosion resistance.   8. The method for producing a fuel cell separator according to claim 7, further comprising a step of forming a corrosion-resistant layer in a region to be a surface of the gas flow path and an electrode contact surface before forming the hydrophilic layer.   The method for producing a separator for a fuel cell according to any one of claims 5 to 9, wherein the hydrophilic layer is formed by plasma treatment. Forming a water repellent layer in a region to be a surface of the gas flow path and an electrode contact surface;
Forming a hydrophilic layer by injection molding in at least a part of a region to be a surface of the gas flow path;
A method for producing a fuel cell separator according to claim 5. Forming a water repellent layer in a region to be a surface of the gas flow path and an electrode contact surface;
Performing a plasma treatment on at least a part of a region to be a surface of the gas flow path;
The manufacturing method of the separator for fuel cells of Claim 5 provided with these. After forming the water repellent layer, forming a mask on the water repellent layer formed in the region to be the electrode contact surface;
Selectively plasma-treating the water-repellent layer with the mask formed;
Removing the mask after the plasma treatment;
The manufacturing method of the separator for fuel cells of Claim 12 provided with these. After forming the water repellent layer, forming a layer made of an organic material on the water repellent layer formed in the region to be the electrode contact surface;
A step of selectively plasma-treating the water-repellent layer in a state where the layer made of the organic material is formed;
The manufacturing method of the separator for fuel cells of Claim 12 provided with these. The method comprising: after forming the water-repellent layer, using a torch type plasma processing apparatus having a size corresponding to a shape of the gas flow path, and performing a plasma treatment on a region to be a surface of the gas flow path. 12. A method for producing a fuel cell separator according to 12.

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