JP2008016228A - Separator for fuel cell, and the fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure required conductivity at an electrode part, while aiming at improvement of adhesiveness at a gas-sealing part. <P>SOLUTION: A fuel cell separator 140, used with at least a part of it in contact with another member in a lamination direction, is provided with a base material layer 10, and conductive layers 16a, 16b laminated on one side face of the base material layer 10. Here, if the degree of adhesion of the base material layer 10 with the first conductive layer 16a is A, and that of the base material layer 1 with the second conductive layer 16b is B, A<B, then if the conductivity of the first conductive layer 16a in the laminating direction is X, and that of the second conductive layer 16b is Y, it is preferable that X>Y. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fuel cell separator, and more particularly to a fuel cell separator having a base layer and a conductive layer covering the surface thereof. The present invention also relates to a fuel cell using the fuel cell separator.

  In a fuel cell stack, a material using carbon or metal as a material of a separator constituting each fuel cell has been studied. Among these, a so-called metal separator using a metal material such as stainless steel is preferably used because it is relatively inexpensive and easy to process.

  When such a metal separator is used, generally, the separator surface and the non-power generation region of the MEA are sandwiched between resin frames including an epoxy resin or a phenol resin so that the MEA and the metal separator are not in direct contact with each other. Laminated and integrated. At this time, an adhesive or the like may be used between the members as necessary.

  In addition, when stainless steel is used as the base material of the metal separator, gold plating, a graphite structure or a carbon-based film (so-called carbon coating) is applied as a surface treatment to improve corrosion resistance and conductivity. .

  Here, an outline of the fuel battery cell will be described. FIG. 3 is a schematic diagram showing an outline of the fuel cell stack, particularly its laminated structure.

  A fuel cell stack generally has a structure in which a plurality of fuel cell cells (single cells) each including an MEA and a separator that sandwiches the MEA are stacked.

  In FIG. 3, MEA 300 forms electrodes each including an electrode catalyst layer and an electrode diffusion layer on both surfaces of polymer electrolyte membrane 302 using, for example, a fluorine-based ion exchange resin such as perfluoro-based or perfluorosulfonic acid-based. And integrated. In FIG. 3, an MEA 300 is used in which a fuel electrode (anode electrode) 304 is formed on one surface side of a polymer electrolyte membrane 302 and an oxidation electrode or an air electrode (cathode electrode) (not shown) is formed on the other surface side. Here, as an example of the MEA 300, a plurality of predetermined fluid manifolds are formed on the outer portion of the polymer electrolyte membrane 302 that forms the outline of each electrode, and those having the same outer shape as the separators 330 and 340 are used. .

  Resin frames 310 and 320 are provided as structural materials on both sides of the MEA 300. The resin frame 310 is formed with an opening 312 that accommodates the fuel electrode 304, and an outer frame 314 that forms an outline of the opening 312 is overlapped with an outer portion of the polymer electrolyte membrane 302. On the other hand, the resin frame 320 is formed with an opening 322 that accommodates the oxidation electrode, and an outer frame 324 that forms an outline of the opening 322 is overlapped with an outer portion of the polymer electrolyte membrane 302.

  MEA 300 and resin frames 310 and 320 are sandwiched between separators 330 and 340. FIG. 4 shows an outline of the configuration of the separator 340 adjacent to the resin frame 320.

  A separator 340 shown in FIG. 4 has a first portion 342 and a second portion 344. The second portion 344 forms an outline of the first portion 342, and a plurality of fluid manifolds through which reaction gas, cooling water, and the like are circulated are opened. When the separator 340 is incorporated into the fuel battery cell, one surface of the second portion 344 is pressed against the outer frame 324 of the resin frame 320 with a predetermined pressure, thereby preventing the reaction gas from leaking out. For this reason, hereinafter, the second portion 344 is also referred to as a gas seal portion. On the other hand, the second portion or the other surface of the gas seal portion 344 is pressed against the separator 430 forming the adjacent fuel cell with a predetermined pressure.

  On the other hand, when one surface of the first portion 342 is incorporated in a fuel cell as shown in FIG. 3, a predetermined space is formed between the MEA 300 and an oxidation electrode (not shown). In the space between the electrode portion 342 thus formed and the oxidation electrode, a desired flow path shape such as a serpentine shape or a parallel shape is formed, and an oxidizing gas such as air or oxygen gas is circulated in the flow path. To do. For this reason, hereinafter, the first portion 342 is also referred to as an electrode portion. On the other hand, the other surface of the first portion or electrode portion 342 is in contact with the separator 430 together with the other surface of the gas seal portion 344.

  The separator 330 has substantially the same shape as the separator 340, and has an electrode part and a gas seal part (not shown). A gas seal portion (not shown) of the separator 330 forms an outer portion of the electrode portion, and a plurality of fluid manifolds for circulating reaction gas, cooling water, and the like are opened. When the separator 330 is incorporated in the fuel battery cell, one side of the gas seal portion is pressed against the outer frame 314 of the resin frame 310 with a predetermined pressure to prevent the reaction gas from leaking. In addition, the other surface of the gas seal portion pressed against the separator forming the adjacent fuel battery cell with a predetermined pressure is generally bonded or sealed to the separator with an adhesive or the like.

  On the other hand, when one side of an electrode portion (not shown) of the separator 330 is incorporated in a fuel cell as shown in FIG. 3, a desired flow path shape is formed between the fuel electrode 304 and hydrogen gas is contained in the flow path. And fuel gas such as reformed gas. Further, the other surface of the electrode portion is in contact with a separator (not shown) together with the other surface of the gas seal portion.

  As described above, the metal separator needs to have good corrosion resistance (acid resistance) and conductivity. For example, a metal separator having a laminated structure as shown in FIG. 5 is used.

  FIG. 5 is a schematic cross-sectional view along the A-A ′ line in the separator 340 shown in FIG. 4. In the cross-sectional view showing the separator structure shown in FIG. 5, for example, the concave and convex shapes such as the gas flow path and the cooling water flow path are omitted, and only the laminated structure is shown.

  In FIG. 5, the separator 340 improves the conductivity of the separator 340 by laminating metal thin film layers 52 and 54, which preferably use gold plating, on both surfaces of the base material layer 50, which is preferably made of stainless steel. ing. Further, a carbon coat layer 56 containing a conductive carbon material and a binder is further provided on the metal thin film layer 52 to not only have conductivity but also improve corrosion resistance. At this time, when the separator 340 is incorporated in the fuel cell shown in FIG. 3, for example, the surface on the metal thin film layer 54 side is provided on the separator 430 side, and the carbon coat layer 56 side is provided on the resin frame 320 side.

  In the fuel cell as shown in FIG. 3, in order to prevent leakage of the reaction gas, for example, a fastening member such as a bolt is used to apply a strong external force in the stacking direction of the members.

  When a strong external force is applied in the laminating direction over a long period of time, in the separator 340 shown in FIGS. 4 and 5, particularly in the gas seal portion 344 strongly held by the resin frame 320 and the separator 430, the carbon coat layer 56 There was a risk of peeling at the interface with the metal thin film layer 52.

  On the other hand, in order to prevent peeling at the interface between the carbon coat layer 56 and the metal thin film layer 52, it is preferable to increase the binder content in the carbon coat layer 56. However, the relative amount of the conductive carbon material contained in the carbon coat layer 56 is reduced. In other words, since it is a conflicting demand to improve adhesion and prevent peeling, and to maintain conductivity, a fuel cell separator that satisfies both of these properties has been demanded.

  By the way, the metal separator which has a laminated structure, or the fuel cell using such a separator is disclosed by patent documents 1-4, for example.

  Patent Document 1 discloses a metal separator for a fuel cell in which a metal-based conductive coating layer containing a highly conductive metal and a graphite-based conductive coating layer are laminated in this order on the surface of a metal separator substrate. Are listed.

  In Patent Document 2, a metal coat layer and a carbon coat layer are provided in this order on a separator base material, and a metal coat layer and a base coat layer are provided between the metal coat layer and the separator base material. A technique for improving the adhesion to the separator substrate is described.

  Patent Document 3 describes providing a coat layer or a base coat layer that enhances adhesion between a carbon coat layer provided on the surface of a metal gas separator and a noble metal plating layer or a stainless steel base layer under the carbon coat layer. Has been.

  Since all of Patent Documents 1 to 3 have a uniform laminated structure as in the conventional separator shown in FIG. 5, they have desired properties such as conductivity, corrosion resistance, and peeling prevention. In order to produce a separator, each material which comprises a laminated structure will be used in large quantities.

  In Patent Document 4, a first carbon coat layer having strong adhesion to the separator base material is provided on the entire surface of the separator base material, and the elastic modulus is high only in a portion where the thickness of the first carbon coat layer is thin. A fuel cell separator in which a second carbon coat containing a material is laminated is described.

JP 2004-111079 A JP 2001-307747 A JP 2002-63914 A JP 2005-251618 A

  However, in the invention described in Patent Document 4, since there are many portions having different laminated structures with respect to one separator, the manufacturing process may be complicated.

  The present invention provides a fuel cell separator having both adhesiveness contributing to prevention of peeling of the layer structure and desired conductivity.

  Another object of the present invention is to provide a fuel cell using a fuel cell separator that has both the adhesiveness contributing to the prevention of peeling of the layer structure and the desired conductivity.

  The configuration of the present invention is as follows.

  (1) A fuel cell separator that has at least a base material layer and a conductive layer laminated on one surface side of the base material layer, and at least a part of which contacts another member in the laminating direction. The degree of adhesion between the base material layer and the conductive layer is A, and the degree of adhesion between the first part provided separately from other members, and the base material layer and the conductive layer is A fuel cell separator, wherein B is a second portion provided in contact with another member, and A <B.

  (2) In the fuel cell separator according to (1), the conductive layer includes a first conductive layer stacked on the first portion and a second conductive layer stacked on the second portion. A fuel that satisfies X> Y, where X is the conductivity in the stacking direction of the first conductive layer and Y is the conductivity in the stacking direction of the second conductive layer. Battery separator.

  (3) In the fuel cell separator according to the above (1) or (2), an adhesion auxiliary film is further provided between the base material layer laminated on the second portion and the conductive layer. Fuel cell separator.

  (4) In the fuel cell separator according to any one of (1) to (3), a non-stick is further provided between the base material layer laminated on the first portion and the conductive layer. A fuel cell separator having an adhesion auxiliary film.

  (5) The fuel cell separator according to (4), wherein the adhesion auxiliary film is a hot-melt type adhesion film, and the non-adhesion auxiliary film is a metal thin film.

  (6) The fuel cell separator according to (4) or (5), wherein the adhesion auxiliary film has a film thickness that is substantially the same as the film thickness of the non-adhesion auxiliary film.

  (7) The fuel cell separator according to any one of (1) to (6), wherein the surface of the base material layer is metal-coated at least in the stacking direction.

  (8) The fuel cell separator according to any one of (1) to (7), wherein the conductive layer includes a conductive material and a binder.

  (9) In the fuel cell separator according to any one of (2) to (8), the first conductive layer is opposed to the oxidation electrode or the fuel electrode through a gas flow path, and The second conductive layer is a fuel cell separator in contact with an adjacent member.

  (10) A fuel cell comprising the fuel cell separator according to any one of (1) to (9) above.

  According to the present invention, in the separator for a fuel cell, it is possible to achieve both improvement in adhesion at a portion in contact with another member and securing of conductivity at a portion facing the electrode.

  Embodiments of the present invention will be described below with reference to the drawings. However, for example, the overall shape and size may be substantially the same as the configuration of the conventional fuel cell separator, but the detailed shape is omitted.

[Embodiment 1]
FIG. 1A is a schematic diagram showing an outline of the configuration of a fuel cell separator 140 according to an embodiment of the present invention. The separator 140 has an electrode part 142 and a gas seal part 144. The gas seal part 144 forms an outline of the electrode part 142. For example, a plurality of fluid manifolds are opened to allow reaction gas, cooling water, and the like to flow therethrough.

  In the embodiment of the present invention, the separator 140 shown in FIG. 1 can be suitably used in the fuel cell stack shown in FIG. 3 instead of the separator 340 shown in FIGS. When the separator 140 is incorporated in the fuel cell 500 shown in FIG. 3 instead of the separator 340, one surface of the gas seal portion 144 is pressed against the outer frame 324 of the resin frame 320 with a predetermined pressure, and the reaction gas Leakage is prevented. At this time, the other surface of the gas seal portion 144 is pressed against the separator 430 forming the adjacent fuel cell with a predetermined pressure. On the other hand, on one surface side of the electrode part 142, a gas flow path is formed between the MEA 300 and an oxidation electrode (not shown) for flowing an oxidizing gas such as air or oxygen gas. Further, the other surface of the electrode part 142 is in contact with the separator 430 together with the other surface of the gas seal part 144.

  Further, instead of the separator 330 having substantially the same shape as the separator 340, a separator 130 having substantially the same shape as the separator 140 shown in FIG. 1 can be used. When the separator 130 is incorporated in the fuel cell 500 shown in FIG. 3 instead of the separator 330, one surface of the gas seal portion is pressed against the outer frame 314 of the resin frame 310 with a predetermined pressure, and leakage of the reaction gas occurs. Is prevented. Further, the other surface of the gas seal portion is pressed against a separator (not shown) that forms the adjacent fuel cell with a predetermined pressure.

  On the other hand, when incorporated in a fuel cell 500 as shown in FIG. 3, a fuel gas such as hydrogen gas or reformed gas is placed between one surface side of the electrode part of the separator 130 and the fuel electrode 304 of the MEA 300. A predetermined space for circulation is formed. Further, the other surface of the electrode portion is in contact with a separator (not shown) together with the other surface of the gas seal portion.

  FIG. 1B is a schematic cross-sectional view along the line B-B ′ in the separator 140 shown in FIG. In the present embodiment, the fuel cell separator 140 includes a base material layer 10 and conductive layers 16 a and 16 b laminated on one surface of the base material layer 10. In order to improve the conductivity perpendicular to the stacking direction, that is, in the plane direction, a metal coat layer 14 is stacked on the other surface of the base material layer 10, and the base material layer 10 and the conductive layer 16a are stacked. , 16b, a metal coat layer 12 is further provided.

  The conductive layers 16 a and 16 b are composed of a first conductive layer 16 a stacked in the electrode part 142 and a second conductive layer 16 b stacked in the gas seal part 144. The first conductive layer 16a and the second conductive layer 16b are different from each other in, for example, the blending ratio or composition thereof, whereby the base layer 10 or the metal coat layer 12 and the conductive layer 16a or 16b. Adhesiveness and electrical conductivity are adjusted to satisfy desired conditions.

  When such a separator 140 is applied to the fuel cell 500 shown in FIG. 3, it is preferable to provide the conductive layers 16 a and 16 b on the MEA 300 side and the metal coat layer 14 side on the resin frame 340 side. .

  For the base material layer 10, for example, stainless steel or aluminum alloy (alumina) can be used, but not limited to this, other materials may be used. Preferably stainless steel is used.

  The metal coat layers 12 and 14 are layers made of a highly conductive metal such as gold or platinum, and are laminated on the base material layer 50 by a preferable method such as plating or vapor deposition. From the viewpoint of cost reduction, a metal layer using copper or the like may be further laminated and used together. The metal coat layer 12 and the metal coat layer 14 are preferably made of the same material, but may be different. Further, the thickness of the metal coat layer 12 and the metal coat layer 14 may be the same or different. In other embodiments, the metal coat layers 12 and 14 can be omitted. However, when the surface of the base material layer 50 is covered with the metal coat layer 12, generally the adhesion to the conductive layers 16a and 16b is improved. For this reason, when the adhesiveness of the conductive layers 16a and 16b to the base material layer 50 itself is not good, it is not preferable to omit the metal coat layer 12.

  The first conductive layer 16a is generally formed by applying a conductive mixture containing, for example, about 1 to 30% by weight of a conductive material and about 99 to 70% by weight of a binder, respectively. During molding, heating, compression, firing, or the like may be performed as necessary. By applying such a conductive material to the surface of the metal coat layer 12 so as to have a predetermined layer thickness and forming the first conductive layer 16a, desired corrosion resistance and conductivity can be ensured. Is possible.

  In the fuel cell 500 illustrated in FIG. 3, the contact resistance in the stacking direction is generally about 300 mΩ · cm or less although it depends on the apparatus. Therefore, when the separator 140 shown in FIG. 1 is applied to the fuel cell 500 shown in FIG. 3, the contact resistance in the stacking direction is the same as that of the conventional fuel cell at least in the portion where the electrode portions 142 are stacked. It is preferable to set the conductivity or conductivity in the stacking direction of the first conductive layer 16a so as to be about, specifically 300 mΩ · cm or less, more preferably about 0 to 200 mΩ · cm.

  On the other hand, the conductive mixture used for the second conductive layer 16b may generally use the same conductive material and binder as the first conductive layer 16a, but the second conductive layer 16b is coated. A strong external force is always applied to the gas seal portion 144 in the stacking direction by other members such as a resin frame and a separator. For this reason, as compared with the first conductive layer 16, the second conductive layer 16 b is placed in an environment where peeling from the metal coat layer 12 is more likely to occur. Therefore, the degree of adhesion (adhesion degree) between the base material layer 10 including the metal coat layer 12 and the first conductive layer 16a is A, and the base material layer 10 including the metal coat layer 12 and the second conductive layer 16b. When the degree of adhesion (adhesion degree) is B, it is necessary to set at least A <B. In order to increase the degree of adhesion, generally, when the same conductive material and binder are used for the first conductive layer 16a and the second conductive layer 16b, the blending amount of the binder should be increased. Can be easily realized. In addition, for example, the degree of adhesion between the first conductive layer 16a and the second conductive layer 16b can be compared based on a thermal shock test to be described later, but it can also be confirmed by other methods. is there.

  From the viewpoint of improving the adhesion between the metal coat layer 12 and the conductive layers 16a and 16b, both the adhesion degree A and the adhesion degree B described above are improved, and the metal coat layer 12 and the second conductivity are improved. It is also possible to improve the adhesion to the conductive layer 16b or the first conductive layer 16a. However, in the conductive mixture containing the conductive material and the binder, when the amount of the binder is increased in order to improve the adhesion with the metal coat layer 12, the amount of the conductive material is relatively increased. Will be reduced. For this reason, if both the adhesiveness A and the adhesiveness B are improved, as a result, the electrical conductivity of the first conductive layer 16a in the electrode portion 142 is less than or equal to the preferable laminating direction conductivity, and the adhesiveness is as a whole. However, the desired conductivity may not be ensured, which is not preferable. Therefore, it is preferable to satisfy X> Y where X is the conductivity in the stacking direction of the first conductive layer 16a and Y is the conductivity in the stacking direction of the second conductive layer 16b.

  As described above, in the present embodiment, the electrode portion 142 ensures desired conductivity, and the gas seal portion 144 is provided with desired adhesiveness, thereby having a simple configuration and a long life. It is possible to obtain a fuel cell separator.

  In the embodiment of the present invention, as a preferable conductive material in the conductive mixture used when forming the conductive layers 16a and 16b, in addition to a carbon-based conductive material such as carbon black and graphite, for example, SBR Etc. Examples of a preferable binder include xylene, but are not limited thereto.

  In the fuel cell separator 140 shown in FIGS. 1 (a) and 1 (b), the value at the maximum thickness in the stacking direction is preferably about 1 mm to 3 mm, but is not limited thereto. You may set suitably according to the performance and physique of the fuel cell 500 to perform. Further, the thickness in the stacking direction of the base material layer 50 is preferably about 0.1 mm to 1 mm, more preferably 0.1 mm to 0.3 mm. The thickness of the metal coat layers 12 and 14 in the stacking direction is preferably about 0.1 to several μm, and more preferably 0.1 to 1 μm. Each of the conductive layers 16a and 16b is preferably about 10 to 100 μm, more preferably 20 to 50 μm. As shown in FIG. 1B, the boundary surfaces of the conductive layers 16a and 16b are not necessarily formed perpendicular to the stacking direction, but are preferably at least smoothly and continuously.

  In the embodiment of the present invention, the thickness of each layer forming the separator 140 does not have to be the same throughout, for example, the shape of the fluid flow path formed on the surface and inside of the separator 140, and the like. It is possible to adjust appropriately according to.

  Further, in the present embodiment, the base material layer 10 does not need to be a uniform layer. For example, layers having different compositions may be laminated, and the electrode part 142 and the gas seal part 144 have different compositions. It is also possible to make it. As another embodiment, a plurality of layers can be laminated on the conductive layers 16a and 16b.

[Embodiment 2]
FIG. 2A is a schematic diagram showing an outline of the configuration of the separator 240 in another embodiment of the present invention. The separator 240 has an electrode part 242 and a gas seal part 244. The gas seal portion 244 forms an outline of the electrode portion 242, and, for example, a plurality of fluid manifolds that circulate reaction gas, cooling water, and the like are opened.

  In the embodiment of the present invention, the separator 240 shown in FIG. 2 can be applied to the fuel cell 500 shown in FIG. 3 in the same manner as the separator 140 shown in FIG. At this time, it is possible to apply the separators 240 and 230 according to the present embodiment in place of the separators 340 and 330 shown in FIG. 3 together with the separator 230 having substantially the same configuration as the separator 240. Since the configuration is substantially the same as that of the first embodiment, the description thereof is omitted.

  FIG. 2B is a schematic cross-sectional view taken along the line C-C ′ in the separator 240 shown in FIG. In the present embodiment, fuel cell separator 240 has base material layer 20, conductive layer 26 is laminated on one surface side of base material layer 20, and metal coating is applied to the other surface side of base material layer 20. Layer 24 is laminated.

  Between the base material layer 20 and the conductive layer 26, a non-adhesion auxiliary film 22a is further laminated in the electrode portion 242, and an adhesion auxiliary film 22b is laminated in the gas seal portion 244.

  The base material layer 20 and the metal coat layer 24 may have substantially the same configuration as the base material layer 10 and the metal coat layer 14 shown in FIG. The conductive layer 26 preferably has at least the same degree of conductivity as the first conductive layer 16a. In other embodiments, similar to the metal coat layer 14, the metal coat layer 24 can be omitted. Furthermore, in another embodiment, a metal coat layer may be further uniformly provided on the surface of the base material layer 20.

  The adhesion auxiliary film 22b is applied for the purpose of assisting the adhesion between the base material layer 20 and the conductive layer 26 in the gas seal portion 244, and is at least 100 ° C or higher, preferably 120 ° C or higher. It is preferable to apply a so-called hot-melt resin having a softening point or glass transition point of about 130 ° C., which has been formed into a thin film in advance, and heat and pressure-bond, but this is not a limitation, and any other method is used. May be.

  On the other hand, the non-adhesion auxiliary film 22a may be any film as long as it does not reduce the conductivity in the stacking direction of the electrode portion 242, but is preferably a metal thin film having the same composition as the metal coat layer 24. .

  In order to laminate the non-adhesion auxiliary film 22a and the adhesion auxiliary film 22b between the base material layer 20 and the conductive layer 26, for example, on the base material layer 20 masked only on the gas seal portion 244. First, a non-adhesive auxiliary film or a metal thin film 22a is laminated, and then an adhesion auxiliary film 22b formed in a predetermined film thickness is disposed on the base material layer 20 by masking only the electrode portion 242, and a conductive layer thereon. After laminating 26, it is possible to apply a method of applying pressure in the laminating direction while heating the separator 240, but not limited thereto, any method may be used.

  Further, by applying the adhesion auxiliary film 22 b in the gas seal portion 244, the adhesion between the conductive layer 26 and the base material layer 20 in the gas seal portion 244 is such that the conductive layer 16 and the base material layer 20 in the electrode portion 242 are bonded. It improves compared with the adhesiveness. That is, when the adhesiveness between the conductive layer 26 and the base material layer 20 in the electrode part 242 is A ′ and the adhesiveness between the conductive layer 26 and the base material layer 20 in the gas seal part 244 is B ′, at least the gas seal. When the adhesiveness between the conductive layer 26 and the base material layer 20 in the portion 244 is increased and A ′ <B ′, peeling can be prevented or suppressed.

  When such a separator 240 is applied to the fuel cell 500 shown in FIG. 3, it is preferable to provide the conductive layer 26 side on the MEA 300 side and the metal coat layer 24 side on the resin frame 340 side.

  As described above, in the present embodiment, the electrode part 242 secures desired conductivity, and the gas seal part 244 is provided with the adhesion auxiliary film 22b to provide desired adhesiveness. It is possible to obtain a fuel cell separator with a simple configuration and a long life.

  In the fuel cell separator 240 shown in FIGS. 2 (a) and 2 (b), the value at the maximum thickness in the stacking direction is preferably about 0.2 mm to 0.8 mm. Not limited to this, it may be set as appropriate depending on the performance and physique of the fuel cell 500 to be used. Further, the thickness in the stacking direction of the base material layer 20, the metal coat layer 24 and the conductive layer 26 may be set in the same manner as the metal coat layer 14 and the conductive layers 16a and 16b in the separator 140.

  Further, the non-adhesive auxiliary film 22a and the adhesion auxiliary film 22b in the stacking direction may have substantially the same thickness or different thicknesses, but it is more preferable to mold them to the same thickness. At this time, a preferable thickness is 5 μm to 100 μm, more preferably 10 μm to 50 μm.

  In the present embodiment, the thicknesses of the respective layers forming the separator 240 do not have to be the same throughout, for example, depending on the shape of the fluid flow path formed on the surface and inside of the separator 240. Needless to say, it can be adjusted as appropriate.

  In the present embodiment, the base material layer 20 does not need to be a uniform layer. For example, layers having different compositions may be laminated, and the electrode portion 242 and the gas seal portion 244 have different compositions. It is also possible to make it. Further, as another embodiment, a plurality of layers can be laminated also on the conductive layer 26. Furthermore, as another embodiment, a plurality of layers can be laminated also on the non-adhesion auxiliary film 22a.

  Below, an example is given about the thermal shock test which can measure an adhesiveness. Note that other measurement methods may be used as long as the results correspond to the results obtained by the following measurement methods, and the method is not limited at all.

<Thermal shock test>
While generating power to the stacked fuel cell stack, it is heated at a predetermined rate from below freezing to around 100 ° C. (for example, the temperature is raised from −20 ° C. to 90 ° C. over 2 minutes), and then cooled to below freezing (for example, 90 ° C. The cycle of lowering the temperature from 0 ° C. to −20 ° C. over 2 minutes is defined as one cycle, and when this is repeated, for example, several thousand cycles, the degree of adhesion is compared for each part to compare the degree of adhesion Is possible.

  The separator for a fuel cell of the present invention is not limited to a polymer electrolyte fuel cell (PEFC) cell and a fuel cell stack in which the fuel cell is laminated, but can be changed by appropriately changing the composition of a binder or an adhesion auxiliary film. This fuel cell can be suitably used.

It is a figure which shows the outline of a structure of the separator 140 for fuel cells in embodiment of this invention. It is a figure which shows the outline of a structure of the separator 240 for fuel cells in other embodiment of this invention. It is a figure which shows the outline of a structure of the fuel cell 500 and a fuel cell stack. It is a figure which shows the outline of a structure of the conventional separator 340 for fuel cells. FIG. 5 is a schematic cross-sectional view along the line A-A ′ of the fuel cell separator shown in FIG. 4.

Explanation of symbols

  10, 20, 50 Base material layer, 12, 14, 24 Metal coat layer, 16a First conductive layer, 16b Second conductive layer, 22a Non-adhesive auxiliary film, 22b Adhesive auxiliary film, 26 Conductive layer, 52, 54 Metal thin film layer, 56 Carbon coat layer, 140, 240, 240, 330, 340, 430 Separator, 142, 242, 342 Electrode part (first part), 144, 244, 344 Gas seal part (second Part), 300 MEA, 302 electrolyte membrane, 304 fuel electrode (anode electrode), 310, 320 resin frame, 312, 322 opening, 314, 324 outer frame, 500 fuel cell (single cell).

Claims (10)

Having at least a base material layer and a conductive layer laminated on one side of the base material layer,
At least a part is in contact with another member in the stacking direction, and is a fuel cell separator used,
A first portion provided with a degree of adhesion between the base material layer and the conductive layer being A and spaced apart from other members;
A degree of adhesion between the base material layer and the conductive layer is B, and a second portion provided in contact with another member;
A separator for a fuel cell comprising A <B. The fuel cell separator according to claim 1,
The conductive layer includes a first conductive layer stacked on the first portion, and a second conductive layer stacked on the second portion,
When the conductivity in the stacking direction in the first conductive layer is X and the conductivity in the stacking direction in the second conductive layer is Y,
X> Y
A separator for a fuel cell, wherein The fuel cell separator according to claim 1 or 2,
A fuel cell separator, further comprising an adhesion auxiliary film between the base material layer and the conductive layer laminated on the second portion. The fuel cell separator according to any one of claims 1 to 3,
A fuel cell separator, further comprising a non-adhesive auxiliary film between the base material layer and the conductive layer laminated on the first portion. The fuel cell separator according to claim 4, wherein
The adhesion auxiliary film is a hot-melt adhesive film,
The non-adhesive auxiliary film is a metal thin film. The fuel cell separator according to claim 4 or 5,
The fuel cell separator is characterized in that the film thickness of the adhesion auxiliary film is substantially the same as the film thickness of the non-adhesion auxiliary film. The fuel cell separator according to any one of claims 1 to 6,
A separator for a fuel cell, wherein the surface of the base material layer is metal-coated at least in the stacking direction. The fuel cell separator according to any one of claims 1 to 7,
The separator for a fuel cell, wherein the conductive layer includes a conductive material and a binder. The fuel cell separator according to any one of claims 2 to 8,
The first conductive layer faces the oxidation electrode or the fuel electrode through the gas flow path,
The fuel cell separator, wherein the second conductive layer is in contact with an adjacent member.   A fuel cell comprising the fuel cell separator according to any one of claims 1 to 9.