JP5680702B2 - Manufacturing method of metal separator for fuel cell - Google Patents

Description

In the present invention, an electrolyte / electrode structure in which a pair of electrodes are disposed on both sides of an electrolyte and a metal separator are laminated, and a reaction gas that is either a fuel gas or an oxidant gas is applied to the surface of the metal separator. a reaction gas flow path to flow in a direction, the method for producing a fuel cell metal separators and reactant gas passage is Ru is formed for circulating the reaction gas in the stacking direction.

  For example, in a polymer electrolyte fuel cell, an electrolyte membrane / electrode structure (MEA) in which an anode side electrode and a cathode side electrode are disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched by separators. ing. This type of fuel cell is usually used as a fuel cell stack by stacking a predetermined number of electrolyte membrane / electrode structures and separators.

  In this fuel cell, a fuel gas flow path (reactive gas flow path) for flowing a fuel gas (reactive gas) facing the anode side electrode and an oxidant facing the cathode side electrode in the plane of each separator An oxidant gas flow path (reactive gas flow path) for flowing gas (reactive gas) is provided. Furthermore, a fuel gas supply communication hole and a fuel gas discharge communication hole, which are reaction gas communication holes that penetrate the separator in the stacking direction and communicate with the fuel gas flow path, and an oxidant gas flow path An oxidant gas supply communication hole and an oxidant gas discharge communication hole which are reaction gas communication holes communicating with the oxidant gas are formed.

  In this case, the reaction gas flow path and the reaction gas communication hole communicate with each other via a connection flow path (reaction gas flow path formed in the bridge portion) having parallel grooves or the like in order to flow the reaction gas smoothly and evenly. ing. However, when the separator and the electrolyte / electrode structure are fastened and fixed with a seal member interposed therebetween, the seal member may enter the connection channel. Thereby, there is a problem that the desired sealing property cannot be maintained, and the connection flow path is blocked and the reaction gas does not flow well.

  Thus, for example, a bipolar plate disclosed in Patent Document 1 is known in order to prevent the seal member from dropping or the like. In Patent Document 1, as shown in FIG. 11, (non-cooled) fuel cells 1a and (cooled) fuel cells 1b are alternately stacked, and the fuel cell 1a includes MEA 2 as a pair of bipolar plates 3a, It is clamped by 3b. A fuel gas inlet 4 is provided between the fuel cells 1a and 1b, and the fuel gas inlet 4 communicates with the fuel gas passage 6 through a port 5 formed in the bipolar plate 3a.

US Patent Application Publication No. 2003/0124405

  However, in Patent Document 1 described above, when the bipolar plate 3a is formed of a metal plate, the metal portion is exposed on the inner surface of the port 5 or the like. For this reason, there is a problem that generated water or condensed water comes into contact with the metal part, and corrosion or the like due to an electrical short circuit (liquid junction) occurs in the bipolar plate 3a.

The present invention has been made to solve this kind of problem, a simple construction and method of manufacturing an fuel cell separator capable of avoiding the exposure of the metal parts to reliably prevent corrosion and liquid junction The purpose is to provide.

In the present invention, an electrolyte / electrode structure having a pair of electrodes disposed on both sides of an electrolyte is sandwiched between a pair of metal separators, and a reaction gas that is either a fuel gas or an oxidant gas is supplied to the metal separator. a reaction gas flow path for flowing in the surface direction of the reactant gas passage for circulating the reaction gas in the stacking direction of the pair of the metallic plates and the electrolyte electrode assembly, a fuel used for a fuel cell is formed cell The present invention relates to a method for manufacturing a metal separator.

  The metal plate constituting at least one of the metal separators is formed with a hole portion that communicates the reaction gas flow path and the reaction gas communication hole.

In this manufacturing method, an injection molding process is performed on the metal plate, thereby integrally forming a seal member covering the inner peripheral surface forming the hole portion, closing the hole portion and continuing on both surfaces of the separator. And a step of forming an insulative communication hole in which a covering portion by the seal member is provided on an inner peripheral surface forming the hole by performing a punching process on the seal portion that closes the hole. In the sealing portion, a separation boundary portion that is separated from the covering portion by a punching process is integrally formed along the inner periphery of the insulating communication hole, and the separation boundary portion is more than the sealing portion. It is set to be thin.

  In the present invention, the insulative communication hole that communicates the reaction gas flow path and the reaction gas communication hole is configured by providing a covering portion by a seal member on the inner peripheral surface of the hole of the metal plate, The metal part is not exposed in the hole. For this reason, generation | occurrence | production of an electrical short-circuit to a metal separator by produced | generated water or condensed water can be prevented, and corrosion of the metal separator can be reliably prevented with a simple configuration.

  Further, in the present invention, an insulating communication hole that connects the reaction gas flow path and the reaction gas communication hole is formed by performing a punching process on the seal portion that closes the hole of the metal plate. Therefore, it is possible to reliably and easily form an insulating communication hole having a desired shape, and to efficiently perform a metal separator manufacturing operation.

It is a principal part disassembled perspective explanatory view of the power generation cell which constitutes the fuel cell concerning the embodiment of the present invention. FIG. 2 is a cross-sectional explanatory view taken along line II-II in FIG. 1 of the fuel cell in which a plurality of power generation cells are stacked. It is explanatory drawing of one surface of the 1st metal separator which comprises the said electric power generation cell. It is explanatory drawing of the other surface of the 1st metal separator which comprises the said electric power generation cell. It is explanatory drawing of one surface of the 2nd metal separator which comprises the said electric power generation cell. It is explanatory drawing of the shaping | molding die for shape | molding a 1st seal member. It is operation | movement explanatory drawing of the said shaping | molding die. It is explanatory drawing at the time of giving a punching process to a said 1st metal separator. It is expansion explanatory drawing of the said 1st metal separator as a product. It is explanatory drawing of the shaping | molding die which has a holding | suppressing part. It is explanatory drawing of the bipolar plate currently disclosed by patent document 1. FIG.

  FIG. 1 is an exploded perspective view of a main part of a power generation cell 12 constituting the fuel cell 10 according to the first embodiment of the present invention. FIG. 2 is a diagram in which a plurality of power generation cells 12 are stacked in the direction of arrow A. FIG. 2 is a cross-sectional explanatory view taken along the line II-II in FIG. 1 of the stacked fuel cell 10.

  As shown in FIG. 1, in the power generation cell 12, an electrolyte membrane / electrode structure 14 is sandwiched between first and second metal separators 16 and 18. The first and second metal separators 16 and 18 are configured by integrally forming a seal member on a metal plate such as a steel plate, a stainless steel plate, an aluminum plate, or a plated steel plate (described later).

  One end edge of the power generation cell 12 in the direction of arrow B (the horizontal direction in FIG. 1) communicates with each other in the direction of arrow A, which is the stacking direction, and oxidant for supplying an oxidant gas, for example, an oxygen-containing gas. Agent gas inlet communication hole (reactive gas communication hole) 20a, cooling medium outlet communication hole 22b for discharging the cooling medium, and fuel gas outlet communication hole (reactive gas communication for discharging a hydrogen-containing gas, for example) Holes) 24b are arranged in the direction of arrow C (vertical direction).

  A fuel gas inlet communication hole (reaction gas communication hole) 24a for supplying fuel gas to the other end edge of the power generation cell 12 in the direction of arrow B and for supplying a cooling medium. The cooling medium inlet communication holes 22a and the oxidant gas outlet communication holes (reaction gas communication holes) 20b for discharging the oxidant gas are arranged in the direction of arrow C.

  As shown in FIGS. 1 and 3, a fuel gas flow path that is a meandering flow path that folds back and forth by one reciprocal half in the direction of arrow B, for example, on the surface 16 a of the first metal separator 16 facing the electrolyte membrane / electrode structure 14. (Reactive gas flow path) 26 is provided. The fuel gas channel 26 includes a plurality of grooves 26a provided by forming the first metal separator 16 into a wave shape.

  As shown in FIG. 1, a cooling medium channel 28 communicating with the cooling medium inlet communication hole 22 a and the cooling medium outlet communication hole 22 b is formed on the surface 16 b opposite to the surface 16 a of the first metal separator 16. . The cooling medium flow path 28 includes a plurality of grooves 28 a extending in the direction of arrow B, for example, by overlapping the first metal separator 16 and the second metal separator 18.

  The first metal separator 16 is provided with a plurality of insulating communication holes 30a and 30b penetrating at positions close to the fuel gas inlet communication hole 24a and the fuel gas outlet communication hole 24b, respectively. The communication hole 30 a communicates the fuel gas inlet communication hole 24 a and the fuel gas flow path 26, while the communication hole 30 b communicates the fuel gas outlet communication hole 24 b and the fuel gas flow path 26.

  On the surfaces 16a and 16b of the first metal separator 16, the first seal member 32 is integrated by injection molding or the like around the outer peripheral end of the metal plate 31 constituting the first metal separator 16. The first seal member 32 uses, for example, a seal material such as EPDM, NBR, fluorine rubber, silicon rubber, fluorosilicon rubber, butyl rubber, natural rubber, styrene rubber, chloroplane, or acrylic rubber, a cushion material, or a packing material. To do.

  The first seal member 32 is formed on the surface 16a of the first metal separator 16, and includes an oxidant gas inlet communication hole 20a, a cooling medium outlet communication hole 22b, a fuel gas outlet communication hole 24b, a fuel gas inlet communication hole 24a, and a cooling medium. It has the 1st protrusion 34 which goes around the inlet communication hole 22a and the oxidizing gas outlet communication hole 20b (refer FIG. 3).

  The first seal member 32 includes, on the surface 16a, a plurality of inlet protrusions 38a that form a plurality of inlet connection passages 36a that connect the communication holes 30a and the fuel gas flow paths 26, the communication holes 30b, and the fuel gas. A plurality of outlet convex portions 38b forming a plurality of outlet connecting passages 36b communicating with the flow path 26 are integrally provided.

  As shown in FIG. 2, the metal plate 31 has a plurality of inlet holes 40 a communicating with the fuel gas inlet communication holes 24 a and the fuel gas flow paths 26, a fuel gas outlet communication hole 24 b and the fuel gas flow paths 26. A plurality of outlet hole portions 40b communicating with each other are provided. The communication hole 30a is formed by providing the coating | coated part 42a by the 1st seal member 32 in the internal peripheral surface which forms the entrance hole part 40a. The communication hole 30b is formed by providing the coating | coated part 42b by the 1st sealing member 32 in the internal peripheral surface which forms the exit hole part 40b.

  As shown in FIG. 4, the first seal member 32 has a second protrusion 44 formed on the surface 16 b of the first metal separator 16. The second protrusion 44 circulates around the oxidant gas inlet communication hole 20a, the fuel gas inlet communication hole 24a, the oxidant gas outlet communication hole 20b, and the fuel gas outlet communication hole 24b.

  The second protrusions 44 include a plurality of inlet protrusions 48a that form a plurality of inlet connection passages 46a that connect the fuel gas inlet communication holes 24a and the communication holes 30a, a fuel gas outlet communication hole 24b, and a plurality of communication holes 30b. And a plurality of outlet convex portions 48b forming a plurality of outlet connecting passages 46b communicating with each other. The second protrusion 44 further includes a plurality of inlet protrusions 52a that form a plurality of inlet connection passages 50a that connect the cooling medium inlet communication hole 22a and the cooling medium flow path 28, the cooling medium outlet communication hole 22b, and the cooling medium. A plurality of outlet convex portions 52b forming a plurality of outlet connecting passages 50b communicating with the flow path 28 are provided.

  As shown in FIGS. 1 and 5, on the surface 18a of the second metal separator 18 facing the electrolyte membrane / electrode structure 14, for example, an oxidant gas flow that is a meandering flow path that folds back and forth once in the direction of arrow B. A passage (reaction gas passage) 54 is provided. The oxidant gas channel 54 includes a plurality of grooves 54a provided by forming the second metal separator 18 into a wave shape.

  The second seal member 56 is integrated with the surfaces 18 a and 18 b of the second metal separator 18 around the outer peripheral end of the second metal separator 18. The second seal member 56 is made of the same material as the first seal member 32 described above.

  As shown in FIG. 5, the second seal member 56 has a protrusion 58 provided on the surface 18 a of the second metal separator 18. The protrusion 58 circulates around the oxidant gas inlet communication hole 20a, the cooling medium outlet communication hole 22b, the fuel gas outlet communication hole 24b, the fuel gas inlet communication hole 24a, the cooling medium inlet communication hole 22a, and the oxidant gas outlet communication hole 20b. .

  Bridge portions 60 a and 60 b are provided between the oxidant gas inlet communication hole 20 a and the oxidant gas outlet communication hole 20 b and the oxidant gas flow path 54. The bridge portions 60 a and 60 b have a plurality of groove portions 62 a and 62 b, and lid members 64 a and 64 b are disposed corresponding to the protrusions 58 of the second seal member 56.

  As shown in FIGS. 1 and 2, the electrolyte membrane / electrode structure 14 includes, for example, a solid polymer electrolyte membrane 70 in which a perfluorosulfonic acid thin film is impregnated with water, and the solid polymer electrolyte membrane 70 sandwiched between them. An anode side electrode 72 and a cathode side electrode 74 are provided.

  The anode side electrode 72 and the cathode side electrode 74 are formed by uniformly applying a gas diffusion layer made of carbon paper or the like and porous carbon particles carrying a platinum alloy on the surface thereof to the surface of the gas diffusion layer. An electrode catalyst layer. The electrode catalyst layers are formed on both surfaces of the solid polymer electrolyte membrane 70.

  FIG. 6 is a cross-sectional view of a main part of a molding die 80 for manufacturing the first metal separator 16 by injection molding the first seal member 32 on the metal plate 31.

  The molding die 80 includes a lower die 82 and an upper die 84, and a cavity 86 having the shape of the first seal member 32 is formed between the lower die 82 and the upper die 84. The cavity 86 has a disk-shaped portion 86a for forming a disk-shaped seal portion (described later) that closes the inlet hole portion 40a and the outlet hole portion 40b, and communicates the disk-shaped portion 86a with the cavity 86 and has a narrow width. Connecting portion 86b (corresponding to a separation boundary portion described later).

  A manufacturing method according to this embodiment for manufacturing the first metal separator 16 in the mold 80 configured as described above will be described below.

  First, as shown in FIG. 6, the metal plate 31 is disposed between the lower mold 82 and the upper mold 84. The metal plate 31 is previously formed with an outlet hole 40b and an inlet hole 40a. The lower mold 82 and the upper mold 84 are clamped to form a cavity 86, and the cavity 86 is filled with a molten rubber material. Therefore, in the cavity 86, the first seal member 32 is integrally formed with the metal plate 31 by the rubber material being cured (see FIG. 7). Then, the mold 80 is opened and the first metal separator 16 is released.

  At that time, the first seal member 32 covers the inner peripheral surfaces of the metal plate 31 forming the outlet hole portion 40b and the inlet hole portion 40a, and has covering portions 42b and 42a. A separation boundary portion 88 is integrally formed on the inner peripheral surfaces of the covering portions 42b and 42a corresponding to the coupling portion 86b of the cavity 86, and the separation boundary portion 88 is sealed corresponding to the disk-shaped portion 86a. Portion 90 is integrally formed.

  Therefore, as shown in FIG. 8, the punching process is performed by pushing the punching pin 92 corresponding to the seal portion 90. Therefore, the seal portion 90 is removed from the first seal member 32 via the separation boundary portion 88, and communication holes 30b and 30a are formed corresponding to the outlet hole portion 40b and the inlet hole portion 40a, respectively. Thereby, the 1st metal separator 16 as a product is obtained (refer FIG. 9).

  In this case, in this embodiment, when the first seal member 32 is injection-molded on the metal plate 31 by the molding process, first, the outlet hole portion 40b and the inlet hole portion 40a are made of a rubber material, specifically, a covering portion. 42b and 42a, the isolation | separation boundary part 88, and the seal | sticker part 90 are obstruct | occluded integrally. Next, the seal portion 90 is separated from the first seal member 32 by a punching process, whereby the communication holes 30b and 30a are formed.

  Therefore, the communication holes 30b and 30a having a desired shape can be formed reliably and easily, and the manufacturing work of the first metal separator 16 can be efficiently performed.

  In addition, a separation boundary portion 88 that is thinner than the seal portion 90 is provided between the seal portion 90 and the first seal member 32. For this reason, when performing the punching process on the seal portion 90 which is an unnecessary portion, the seal portion 90 can be reliably separated at the separation boundary portion 88. Accordingly, there is an advantage that it is possible to obtain the highly accurate and high quality communication holes 30b and 30a by preventing the seal portion 90 from remaining.

  Next, the operation of the fuel cell 10 will be described below.

  First, as shown in FIG. 1, a fuel gas such as a hydrogen-containing gas is supplied to the fuel gas inlet communication hole 24a, and an oxidant gas such as an oxygen-containing gas is supplied to the oxidant gas inlet communication hole 20a. Further, a cooling medium such as pure water, ethylene glycol, or oil is supplied to the cooling medium inlet communication hole 22a.

  Therefore, as shown in FIGS. 1 and 4, the fuel gas moves from the fuel gas inlet communication hole 24a to the surface 16a side of the first metal separator 16 through the plurality of inlet connection passages 46a and the plurality of communication holes 30a. To do. As shown in FIG. 3, the fuel gas that has moved to the surface 16 a side is introduced into the fuel gas flow channel 26 from the plurality of inlet connection passages 36 a. The fuel gas is supplied to the anode side electrode 72 constituting the electrolyte membrane / electrode structure 14 while reciprocating in the direction of arrow B.

  On the other hand, as shown in FIGS. 1 and 5, the oxidant gas is introduced from the oxidant gas inlet communication hole 20 a through the bridge portion 60 a of the second metal separator 18 into the oxidant gas flow path 54. The oxidant gas is supplied to the cathode side electrode 74 constituting the electrolyte membrane / electrode structure 14 while reciprocating in the direction of arrow B.

  Therefore, in the electrolyte membrane / electrode structure 14, the fuel gas supplied to the anode side electrode 72 and the oxidant gas supplied to the cathode side electrode 74 are consumed by an electrochemical reaction in the electrode catalyst layer, and power generation is performed. Is done.

  Next, as shown in FIG. 3, the fuel gas supplied to and consumed by the anode side electrode 72 moves to the surface 16b side through the plurality of outlet connection passages 36b and the plurality of communication holes 30b. As shown in FIG. 4, the fuel gas that has moved to the surface 16b side is discharged in the direction of arrow A along the fuel gas outlet communication hole 24b from the plurality of outlet connection passages 46b.

  Similarly, the oxidant gas supplied to and consumed by the cathode side electrode 74 is discharged from the bridge portion 60b in the direction of arrow A along the oxidant gas outlet communication hole 20b (see FIG. 1).

  The cooling medium supplied to the cooling medium inlet communication hole 22a is introduced into the cooling medium flow path 28 between the first and second metal separators 16 and 18, and then flows in the direction of arrow B. The cooling medium is discharged from the cooling medium outlet communication hole 22b after the electrolyte membrane / electrode structure 14 is cooled (see FIG. 1).

  In this case, in this embodiment, as shown in FIGS. 2 and 9, the communication hole 30 b that connects the fuel gas outlet communication hole 24 b and the fuel gas flow path 26 is formed on the inner surface of the outlet hole 40 b of the metal plate 31. The covering portion 42b is provided, and the metal portion is not exposed to the communication hole 30b.

  Similarly, the communication hole 30a that connects the fuel gas inlet communication hole 24a and the fuel gas flow path 26 is configured by providing a covering portion 42a on the inner surface of the inlet hole 40a of the metal plate 31, and the communication hole 30a. The metal part is not exposed.

  Thereby, it is possible to prevent an electrical short circuit from occurring in the first metal separator 16 due to the generated water or the condensed water. Therefore, it is possible to reliably prevent corrosion of the first metal separator 16 with a simple configuration.

  In addition, when the first seal member 32 is injection-molded on the metal plate 31, it is not necessary to provide a mold pressing portion around the outlet hole 40b and the inlet hole 40a. Specifically, as shown in FIG. 10, in the mold 7 that does not close the inlet hole 40 a and the outlet hole 40 b, the lower mold 7 a and the upper mold 7 b prevent the molding burr from flowing out of the cavity 8. The holding parts 9a and 9b are provided on the upper side. For this reason, the range T of the mold pressing part in which the pressing parts 9a and 9b are provided becomes necessary.

  On the other hand, in this embodiment, since the mold holding portion is not required, the dimension from the fuel gas outlet communication hole 24b to the fuel gas flow path 26 and the distance from the fuel gas inlet communication hole 24a to the fuel gas flow path 26 are provided. There is an advantage that the size can be shortened as much as possible and the entire power generation cell 12 can be easily reduced in size.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 12 ... Power generation cell 14 ... Electrolyte membrane / electrode structure 16, 18 ... Metal separator 20a ... Oxidant gas inlet communication hole 20b ... Oxidant gas outlet communication hole 22a ... Cooling medium inlet communication hole 22b ... Cooling medium outlet Communication hole 24a ... Fuel gas inlet communication hole 24b ... Fuel gas outlet communication hole 26 ... Fuel gas flow channel 28 ... Cooling medium flow channel 30a, 30b ... Communication hole 31 ... Metal plates 32, 56 ... Seal members 34, 44, 58 ... Projection 36a, 46a, 50a ... Inlet connection passage 36b, 46b, 50b ... Outlet connection passage 40a ... Inlet hole portion 40b ... Outlet hole portion 42a, 42b ... Cover portion 54 ... Oxidant gas flow path 60a, 60b ... Bridge portion 70 ... Solid polymer electrolyte membrane 72 ... Anode side electrode 74 ... Cathode side electrode 80 ... Molding die 82 ... Lower die 84 ... Upper die 86 ... Cavity 88 ... Separation boundary Part 90 ... seal part

Claims (1)

An electrolyte / electrode structure having a pair of electrodes disposed on both sides of the electrolyte is sandwiched between a pair of metal separators, and a reaction gas, which is either a fuel gas or an oxidant gas, is placed in the surface direction of the metal separator. A fuel cell metal separator for use in a fuel cell in which a reaction gas flow channel for flowing and a reaction gas communication hole for flowing the reaction gas in the stacking direction of the electrolyte / electrode structure and the pair of metal separators are formed. A manufacturing method comprising:
In the metal plate constituting at least one of the metal separators, a hole portion that communicates the reaction gas flow path and the reaction gas communication hole is formed,
A step of integrally molding a sealing member that covers the inner peripheral surface of the metal plate to cover the inner peripheral surface of the metal plate and that is continuous on both sides of the separator by performing an injection molding process on the metal plate;
Forming an insulative communication hole in which a covering portion by the seal member is provided on the inner peripheral surface forming the hole portion by performing a punching process on the seal portion that closes the hole portion;
Have
The seal portion is integrally formed along the inner periphery of the insulating communication hole with a separation boundary portion separated from the covering portion by a punching process,
The method of manufacturing a metal separator for a fuel cell, wherein the separation boundary portion is set thinner than the seal portion.

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