JP2005174642A - Separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator excellent in reliability and corrosion resistance. <P>SOLUTION: Rubber (including elastomer) layers 31 are formed on both sides of a metal thin plate 30 as a core member. Grooves parallel to one another are formed in the rubber layer 31 of a separation part 13. The grooves in the rubber layer 31 are used as hydrogen gas passages and oxygen gas passages. Since the separator uses the metal thin plate as the core member, the separator is less in warpage and deformation and more excellent in reliability and corrosion resistance than a separator made of rubber only. Furthermore, in the separation part 13, a condition that the sides of the metal thin plate 30 are coated with the rubber layers 31 prevents a surface change of properties due to corrosion and others caused by hydrogen gas, oxygen gas, and cooling water from occurring. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a separator provided in a stack type polymer electrolyte fuel cell.

  Conventionally, the necessity of energy saving for effective use of limited energy resources and prevention of global warming has been widely recognized. Today, thermal power supplies energy demand in the form of converting thermal energy into electric energy.

  However, coal and oil necessary for thermal power generation are resources with limited reserves, and new energy resources to replace them are required. Therefore, attention is being focused on fuel cells that generate chemical power using hydrogen as a fuel.

  The fuel cell has two electrodes and an electrolyte sandwiched between the electrodes. At the cathode, the supplied hydrogen is ionized to form hydrogen ions that move through the electrolyte toward the anode. At the anode, the supplied oxygen reacts with hydrogen ions that have moved through the electrolyte to generate water. Electrons generated when hydrogen is ionized move from the cathode through the wiring to the anode, whereby a current flows and electricity is generated.

  Fuel cells are classified into four types mainly based on the difference in electrolyte. Solid electrolyte fuel cell (SOFC) using ion conductive ceramics as electrolyte, solid polymer fuel cell (PEFC) using hydrogen ion conductive polymer membrane as electrolyte, phosphorus using high concentration phosphoric acid as electrolyte There are four types: an acid fuel cell (PAFC) and a molten carbonate fuel cell (MCFC) using an alkali metal carbonate as an electrolyte. Among them, development of a polymer electrolyte fuel cell (PEFC) having an operating temperature as low as 80 ° C. is in progress.

  The structure of the polymer electrolyte fuel cell includes an electrolyte layer provided with a catalyst electrode on the surface, a separator provided with a groove for supplying hydrogen and oxygen, sandwiching the electrolyte layer from both sides, and collecting electricity generated by the electrode It includes a current collector plate. As with the electrolyte layer, improvements have been made to the separator.

As the required characteristics of the separator, it is necessary to have high conductivity, high airtightness with respect to the fuel gas and the oxidant gas, and high corrosion resistance against the reaction when oxidizing and reducing hydrogen and oxygen.
In order to satisfy these requirements, the following separator materials are used.

  The most commonly used is dense carbon. Dense carbon is excellent in electrical conductivity and corrosion resistance, and has high mechanical strength. Also, it has good workability and is lightweight. However, it is vulnerable to vibrations and shocks and requires cutting, which increases the processing cost. Moreover, it is necessary to perform a gas impermeability treatment.

  Plastics are also used, and thermosetting resins such as phenol resins and epoxy resins are used. The main feature of plastics is that they are low-cost, but they have poor dimensional stability and poor conductivity.

  From the viewpoints of conductivity, workability, sealing properties, etc., metals are often used. As the metal, titanium and stainless steel are mainly used. However, metal is easily corroded, and metal ions are taken into the electrolyte membrane and ion conductivity is lowered. Therefore, it is necessary to perform gold plating on the separator surface.

  Rubber is also used, and ethylene-propylene-diene rubber is used. Rubber has low gas permeability and high sealing properties.

  Patent Document 1 discloses a solid polymer electrolyte fuel cell. In this solid polymer electrolyte fuel cell, a metal thin plate on which a passive film is easily formed by the atmosphere, such as stainless steel and titanium alloy, is used as a separator, and the separator is processed into a predetermined shape by pressing.

JP-A-8-180883

  A separator made of rubber has low gas permeability but low rigidity, and deteriorates in a high heat environment. Therefore, there is a problem that warpage and deformation are large and cannot be used for a long time.

  An object of the present invention is to provide a separator having excellent reliability and corrosion resistance.

The present invention is a separator interposed between a plurality of electrolyte assemblies provided with a catalyst electrode on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium,
Having a separation part for separating the flow paths of the fuel gas and the oxidant gas;
In the separation part, a rubber layer is formed on the surface of the flat metal plate that is the core material,
The rubber layer is provided with the flow path.

  Further, the present invention is characterized in that a highly conductive layer having conductivity higher than that of the rubber layer is formed on the surface of the rubber layer.

  In the invention, it is preferable that the highly conductive layer is formed in a region where at least the rubber layer is in contact with the electrolyte assembly.

Further, the present invention is a separator interposed between a plurality of electrolyte assemblies provided with a catalyst electrode on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium,
Having a separation part for separating the flow paths of the fuel gas and the oxidant gas;
In the separation part, a highly conductive layer having conductivity higher than the conductivity of the rubber layer and the rubber layer is formed on the surface of the flat metal plate as the core material,
The highly conductive layer is provided with the flow path.

Further, the present invention has a seal portion that is provided on the outer peripheral portion and prevents leakage of fuel gas and oxidant gas,
The seal portion is a seal protrusion formed by forming a rubber layer on the surface of the metal plate and extending in parallel to the catalyst electrode forming surface of the electrolyte assembly, so that the top thereof is pressed against the electrolyte assembly by a spring force. It has the seal | sticker projection part comprised, It is characterized by the above-mentioned.

  Further, the present invention is characterized in that the separation portion and the seal portion are integrally formed by pressing.

According to the present invention, there is provided a separator interposed between a plurality of electrolyte assemblies in which a catalyst electrode is provided on a surface in the thickness direction of an electrolyte layer containing an electrolyte medium, and the separator has a flow path for fuel gas and oxidant gas. And a separation part for separation.

  In the separation part, a rubber layer is formed on the surface of the flat metal plate as the core material, and the flow path is provided in the rubber layer.

  Thereby, by using a flat metal plate as a core material, it is possible to provide a separator with less warpage and deformation and excellent reliability compared to a separator made only of rubber. Since the metal plate as the core material is covered with the rubber layer, surface changes such as corrosion caused by hydrogen gas, oxygen gas, and cooling water can be prevented.

  According to the invention, a highly conductive layer having conductivity higher than that of the rubber layer is formed on the surface of the rubber layer. Thereby, the contact resistance between the separator and the electrolyte assembly can be reduced.

  Further, according to the present invention, since the highly conductive layer is formed at least in the region where the rubber layer is in contact with the electrolyte assembly, the contact resistance between the separator and the electrolyte assembly can be reduced more effectively.

  According to the present invention, there is also provided a separator interposed between a plurality of electrolyte assemblies in which a catalyst electrode is provided on the surface in the thickness direction of the electrolyte layer containing the electrolyte medium, the separator being a flow path for fuel gas and oxidant gas And a separation unit for separating the components.

  In the separation portion, a rubber layer and a highly conductive layer having higher conductivity than the conductivity of the rubber layer are formed on the surface of the flat metal plate as the core material. The flow path is provided in the highly conductive layer.

  Thereby, by using a flat metal plate as a core material, it is possible to provide a separator with less warpage and deformation and excellent reliability compared to a separator made of only rubber or a thermosetting polymer. Since the metal plate as the core material is coated with the rubber layer or the thermosetting polymer layer, surface changes such as corrosion caused by hydrogen gas, oxygen gas, and cooling water can be prevented. Furthermore, since the contact resistance with the electrolyte assembly can be reduced and the resistance of the entire current path can be greatly reduced, the power recovery rate can be improved.

  Further, according to the present invention, the seal portion is provided on the outer peripheral portion and prevents leakage of fuel gas and oxidant gas, and the seal portion is formed with a rubber layer on the surface of the metal plate. A seal protrusion that extends parallel to the electrode forming surface, the top of which is configured to be pressed against the electrolyte assembly by a spring force.

  This eliminates the need for sealing members such as O-rings and gaskets, which are conventionally required, and can reduce the number of members of the fuel cell.

  According to the invention, the separation part and the seal part are integrally formed by press working. Thereby, the manufacturing process of a fuel cell can be shortened.

  FIG. 1 is a perspective view schematically showing a state in which a polymer electrolyte fuel cell (abbreviated as PEFC) 100 is developed. The PEFC 100 includes a separator 1, a fuel battery cell 2, a current collector plate 3, an insulating sheet 4, an end flange 5, and an electrode wiring 12. The PEFC 100 is configured in a so-called stack state in which a plurality of fuel cells 2 are connected in series in order to obtain a high voltage and a high output. In order to configure this stack state, a separator is disposed between the fuel cells 2, and hydrogen and oxygen are supplied to each fuel cell 2 and the generated electricity is recovered. Therefore, as shown in FIG. 1, the fuel cells 2 and the separators 1 are alternately arranged. The separator 1 is arranged on the outermost layer of this arrangement, and the current collector plate 3 is provided on the outer side of the separator 1. The current collector plate 3 is provided to collect and take out the electricity collected by each separator 1 and is connected to the electrode wiring 12. The insulating sheet 4 is provided between the current collector plate 3 and the end flange 5, and prevents current from leaking from the current collector plate 3 to the end flange 5. The end flange 5 is a case for holding the plurality of fuel cells 2 in a stacked state.

  A hydrogen gas supply port 6, a cooling water supply port 7, an oxygen gas supply port 8, a hydrogen gas discharge port 9, a cooling water discharge port 10 and an oxygen gas discharge port 11 are formed in the end flange 5. The gas and water fluid supplied from each supply port passes through each forward path penetrating in the stacking direction of the fuel cells 2 and is folded back by the outermost separator 1 and is discharged from each discharge port through each return path.

  The forward path and the return path are branched by each separator 1, and each fluid flowing in the forward path flows into the return path through a flow path formed by the separator 1 and parallel to the surface direction of the fuel cell 2. Since hydrogen gas and oxygen gas are consumed in the fuel battery cell 2, unreacted gas is discharged through the return path. The discharged unreacted gas is recovered and supplied again from the supply port. Since water is generated by the reaction of oxygen and hydrogen in the vicinity of the oxygen gas flow path, the discharged oxygen gas contains water. In order to supply the discharged oxygen gas again, it is necessary to remove water.

  The hydrogen gas that is a fuel gas and the oxygen gas that is an oxidant gas do not need to be hydrogen and oxygen alone, but can be any gas other than hydrogen and oxygen that does not deteriorate or denature the flow path in contact. May be included. For example, air containing nitrogen as oxygen gas may be used. The hydrogen source is not limited to hydrogen gas, and may be methane gas, ethylene gas, natural gas, or ethanol.

  FIG. 2 is a horizontal sectional view of the unit battery 101 including the separator 1 according to the first embodiment of the present invention. The unit battery 101 is composed of one fuel battery cell 2 and two separators 1 arranged on both sides of the unit battery 101. The unit battery 101 has a minimum configuration capable of generating electric power by supplying hydrogen and oxygen.

The fuel cell 2 as an electrolyte assembly includes a polymer film 20 as an electrolyte medium and a catalyst electrode 21 formed on the surface of the polymer film 20 in the thickness direction. The MEA (Membrane Electrode)
Also called Assembly.

  The polymer membrane 20 is a proton conductive electrolyte membrane that transmits hydrogen ions (protons), and a perfluorosulfonic acid resin membrane (for example, a product name “Nafion” manufactured by DuPont) is often used.

  The catalyst electrode 21 is laminated on the surface of the polymer film 20 in the thickness direction as a carbon layer containing a catalyst metal such as platinum or ruthenium. When hydrogen gas or oxygen gas is supplied to the catalyst electrode 21, an electrochemical reaction occurs at the interface between the catalyst electrode 21 and the polymer film 20 to generate DC power.

  The polymer film 20 has a thickness of about 0.1 mm, and the catalyst electrode 21 is formed with a thickness of several μm although it varies depending on the catalyst metal contained therein.

The separator 1 has a separation part 13 that separates the flow paths of hydrogen gas and oxygen gas, and a seal part 14 that is provided on the outer periphery and prevents leakage of hydrogen gas and oxygen gas. In the present embodiment, the catalyst electrode 21 is not formed on the entire surface of the polymer film 20 but has a width 1 to
The polymer film 20 is exposed on the surface over 20 mm, desirably 5 to 10 mm. The separator 13 of the separator 1 is formed in a region facing the region where the catalyst electrode 21 is formed, and the seal portion is formed in a region facing the region where the polymer film 20 is exposed.

  In the separation part 13, a plurality of flow channel grooves parallel to each other and parallel to the surface on which the catalyst electrode 21 is formed are formed on both surfaces in the thickness direction. This channel groove has a concave shape in a cross section perpendicular to the gas flow direction. A space surrounded by the separation block 15 and the catalyst electrode 21 provided at a predetermined interval is a hydrogen gas flow path 16 and an oxygen gas flow path 17. The separation block 15 separates the hydrogen gas flow channel 16 and the oxygen gas flow channel 17 so as not to mix hydrogen gas and oxygen gas, and is in contact with the catalyst electrode 21, at the interface between the polymer film 20 and the catalyst electrode 21. The generated DC power is extracted as a DC current. The extracted direct current is collected on the current collector plate 3 through another separation block 15 or the like.

  The channel grooves adjacent to each other are formed so that the open surfaces are in the same direction, and accordingly, the hydrogen gas channel 16 is set on one side and the oxygen gas channel is set on the other side. 17 is set. That is, the gas flow path is set so that the same gas contacts the same catalyst electrode 21. Further, as shown in FIG. 2, the two separators 1 constituting one unit battery 101 are arranged so that the open portions of the flow channel grooves face each other with the fuel battery cell 2 interposed therebetween. That is, the two separators 1 are arranged so as to have a plane-symmetrical relationship with the center of the fuel cell 2 as the symmetry plane. However, the setting of the gas flow path is not a plane-symmetrical relationship, and the flow path grooves facing each other with the fuel cell 2 interposed therebetween are set so as to form gas flow paths for different gases. For example, as shown in FIG. 2, one of the gas flow paths facing each other across the fuel cell 2 is a hydrogen gas flow path 16, and the other is an oxygen gas flow path 17.

  Electric power can be generated by arranging the separator 1 and setting the gas flow path as described above.

  The flow path formed by the flow path groove and the catalyst electrode 21 is not limited to hydrogen gas and oxygen gas, and cooling water may flow. When flowing the cooling water, it is preferable to flow in any of the channel grooves facing each other with the fuel battery cell 2 interposed therebetween.

  Although details will be described later, a flat metal thin plate is used as the core material of the separator 1. For example, metal thin plates such as iron, aluminum, and titanium, particularly stainless steel (for example, SUS304) steel plates, SPCC (general cold rolled steel plates), and corrosion-resistant steel plates are preferable.

  The seal portion 14 is formed with a seal protrusion that extends parallel to the surface on which the catalyst electrode 21 is formed. The seal projection has an inverted U-shaped or inverted V-shaped cross section perpendicular to the gas flow direction. By making the core material of the separator 1 a metal thin plate, the top portion 18 of the seal projection is pressed against the exposed polymer film 20 by a spring force. Sealing at this pressure contact position can prevent leakage of hydrogen gas and oxygen gas. Further, by forming the seal protrusion in an inverted U shape or an inverted V shape, the membrane contact area of the top portion 18 is reduced, and a high-pressure seal similar to that of an O-ring is realized.

In order to press-contact the top 18 of the seal protrusion against the polymer film 20 by a spring force, the position of the top 18 of the seal protrusion in the separator 1 in a state where it does not come into contact with the polymer film 20, that is, before the PEFC 1 is assembled. However, the seal part 14 is formed in advance so that the PEFC 1 is assembled and the polymer film 20 side is further from the position where it is in contact with the polymer film 20. Specifically, as shown in FIG. 3A, in the state where the PEFC 1 is assembled, the position of the top portion 18 of the seal projection is determined based on the virtual contact surface A with the catalyst electrode 21. The distance between the contact surface and the top portion 18 is such that the thickness t1 of the catalyst electrode 21 is reached. Therefore, PEFC
In the state before 1 is assembled, as shown in FIG. 3B, the position of the top portion 18 of the seal protrusion is formed so that the distance from the contact surface with the catalyst electrode 21 is t2 larger than t1. That's fine. Since the connecting portion between the separation portion 13 and the seal projection acts as a spring, the pressure when the top portion 18 is pressed against the polymer film during assembly is determined by this spring force and the contact area. The spring force is obtained by multiplying the spring constant (elastic constant) by the amount of displacement according to Hooke's law. In the separator 1, the spring constant is determined by the material of the separator 1 and the shape of the seal portion 14. The amount of displacement is Δt = t2−t1. Accordingly, the seal pressure can be easily adjusted by changing t2 during processing in a state where the material and shape are determined in advance and the spring constant is determined. Needless to say, the material and shape may be changed in order to achieve the optimum sealing pressure.

  As described above, since the two separators 1 sandwiching the fuel cell 2 are arranged so as to have a plane-symmetrical relationship, the pressure contact position by the top portion 18 of the seal projection also has a plane of symmetry about the center of the fuel cell 2. As shown in FIG. The sealing performance is improved by the pressure contact position of the top 18 being opposed.

  FIG. 4 is an enlarged view of a main part of the separation unit 13 in the first embodiment. In the present embodiment, rubber (including elastomer) layers 31 are formed on both surfaces of a thin metal plate 30 as a core material, and grooves parallel to each other are provided in the rubber layer 31 of the separation unit 13. The groove of the rubber layer 31 becomes the hydrogen gas channel 16 and the oxygen gas channel 17. By covering the surface of the metal thin plate 30 with the rubber layer 31 in the separation unit 13, it is possible to prevent surface changes such as corrosion due to hydrogen gas, oxygen gas, and cooling water.

  In the separation unit 13, the rubber layer 31 comes into contact with the catalyst electrode 21, and direct current power generated at the interface between the polymer membrane 20 and the catalyst electrode 21 is taken out as direct current, passes through the separator 1, and is a current collector plate. To be collected. As described above, since the rubber layer 31 needs to have conductivity, as the rubber, for example, general-purpose rubbers such as isoprene rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber and ethylene-propylene rubber, gas permeation resistance That have been made conductive by adding a carbon filler to a special rubber such as epichlorohydrin rubber having heat resistance and heat resistance can be used. In particular, an allyl addition polymerization type polyisobutylene excellent in heat resistance and acid resistance is preferably added with a carbon filler.

A synthetic resin layer using a synthetic resin instead of rubber may be provided. As the synthetic resin, a resin obtained by adding a carbon filler to a phenol resin, an epoxy resin, a fluorine-containing resin, or the like can be used. In particular, a fluorine-containing resin excellent in corrosion resistance is preferable. For example, PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), FEP (tetrafluoroethylene-hexafluoropropylene copolymer). Polymer), EPE (tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer), ETFE (tetrafluoroethylene-ethylene copolymer), PCTFE (polychlorotrifluoroethylene), ECTFE (chlorotrifluoroethylene). -Ethylene copolymer), PVDF (polyvinylidene fluoride), PVF (polyvinyl fluoride), THV (tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer), VD -HFP (vinylidene fluoride - hexafluoropropylene copolymer), TFE-P (vinylidene fluoride - propylene copolymer) is preferably obtained by adding carbon filler or the like.
The metal thin plate 30 may be covered with the rubber layer 31 for the seal portion 14 as well.

  FIG. 5 is an enlarged view of a main part of the seal portion 14 in the first embodiment. In the present embodiment, the separator 1 forms the coating layer 31 and covers the surface of the thin metal plate 30. In the seal portion 14, the rubber layer 31 is in contact with the polymer film 20 for sealing.

  When the metal thin plate 30 is brought into direct contact with the polymer film 20, a minute gap is generated between the deformed portion and the surface of the polymer film 20 when the top 18 of the seal protrusion is deformed. There is a risk of fluid leaking from the gap. When the seal portion 14 is covered with the rubber layer 31 which is a highly elastic body, the contact portion is deformed by the pressure contact of the top portion 18 due to the spring force, and no gap is formed between the surface of the polymer film 20 and thus the sealing property. Will improve.

  The surface of the metal thin plate 30 is coated with the rubber layer 31 mainly by the following two methods. In the first method, the surface of the metal thin plate 30 to be coated is roughened by oxidation treatment or the like to form a surface treatment layer, and the rubber layer 31 is brought into close contact by an anchor effect. In the second method, when the surface roughening does not provide sufficient adhesion to the rubber layer 31, the rubber layer 31 is bonded via the adhesive layer. As the adhesive layer, for example, triazine thiols and polyanilines are used. Since triazine thiols and polyanilines diffused on the metal surface exhibit conductivity, the generated DC power can be taken out as a DC current. These methods can be similarly applied to the following embodiments.

  As described above, by using a metal thin plate as a core material, it is possible to provide a separator that has less warpage and deformation, and is excellent in reliability and corrosion resistance, compared to a separator made of only rubber.

  FIG. 6 is an enlarged view of a main part of the separation unit 13 in the second embodiment. In the present embodiment, the separator 1 includes the metal thin plate 30, the rubber layer 31, and the high conductive layer 32, and the high conductive layer 32 having higher conductivity than the rubber layer 31 is formed on the surface of the rubber layer 31. .

  When the contact resistance between the rubber layer 31 and the catalyst electrode 21 is high and a sufficient power recovery rate cannot be obtained, the contact resistance with the catalyst electrode 21 is formed by forming the highly conductive layer 32 on the surface of the rubber layer 31. The recovery rate can be improved. It is preferable to use a mixture of a binder resin and carbon (hereinafter referred to as “carbon / resin compound”) for the highly conductive layer 32. The highly conductive layer 32 achieves high conductivity with carbon and reduces gas permeability with a binder resin. As the carbon content of the carbon / resin compound increases, the electrical resistance of the highly conductive layer 32 decreases. However, since the binder resin content decreases, the gas permeability increases. From the balance between electric resistance and gas permeability, the resin content of the carbon resin compound is preferably in the range of 20 to 30%. As carbon to be contained, artificial graphite, carbon fiber, carbon nanotube, fullerene and the like are used, and it is particularly preferable to use artificial graphite. As the binder resin, polyisobutylene rubber or the like is preferably used.

  FIG. 7 is an enlarged view of a main part of the seal portion 14 in the second embodiment. In the present embodiment, the separator 1 includes a thin metal plate 30, a rubber layer 31, and a highly conductive layer 32. In the seal portion 14, the highly conductive layer 32 is in contact with the polymer film 20 and sealed. For the rubber layer 31, the same rubber as that of the first embodiment can be used.

  In the second embodiment, the high conductive layer 32 may be provided only in the separation part 13 and the high conductive layer 32 may not be provided in the seal part 14. This is because there is no need to consider contact resistance with the polymer film 20 because no electric power is generated in the seal portion 14. However, in the manufacturing process, the highly conductive layer 32 may be formed on the entire surface of the metal thin plate 30 including the seal portion 14.

FIG. 8 is an enlarged view of a main part of the separation unit 13 in the third embodiment. In the present embodiment, the separator 1 includes the metal thin plate 30, the rubber layer 31, and the high conductive layer 32, and the high conductive layer 32 is formed only in a region in contact with the catalyst electrode 21 on the surface of the rubber layer 31. For the highly conductive layer 32, the same carbon / resin compound as the highly conductive layer 32 of the second embodiment can be used.

  A reduction in contact resistance due to the high conductive layer 32 is sufficiently effective if the high conductive layer 32 is formed only in the contact region between the rubber layer 31 and the catalyst electrode 21. Therefore, the formation region of the high conductive layer 32 can be reduced, and the contact resistance can be effectively reduced with a small amount of carbon / resin compound.

  FIG. 9 is an enlarged view of a main part of the separation unit 13 in the fourth embodiment. In the present embodiment, as in the second and third embodiments, the separator 1 is composed of a metal thin plate, a rubber layer, and a highly conductive layer. However, as shown in FIG. On the surface of the rubber layer 33, a highly conductive layer 34 having a predetermined thickness is formed. On the surface of the rubber layer 33, a highly conductive layer 34 provided with a groove serving as a gas flow path of the separation portion 13 is formed.

  By covering the surface of the metal thin plate 30 with the rubber layer 33 in the separation unit 13, it is possible to prevent surface changes such as corrosion due to hydrogen gas, oxygen gas, and cooling water.

  Unlike the second embodiment, most of the separation portion 13 is made of the highly conductive layer 34. Therefore, in addition to the contact resistance with the catalyst electrode 21, the resistance of the entire current path can be greatly reduced. In addition, the power recovery rate can be further improved.

  The rubber layer 33 can use the same rubber as the rubber layer 31 of the first embodiment, and the high conductive layer 34 has the same carbon / resin compound as the high conductive layer 32 of the second embodiment. Can be used. Note that the highly conductive layer 34 may be provided on the separation portion 13 and the seal portion 14, or may be provided only on the separation portion 13 and not on the seal portion 14, as in the second embodiment.

  For the seal portion 14 in the third and fourth embodiments, the highly conductive layer 32 is not formed, and the rubber layer 31 as shown in FIG. Alternatively, the highly conductive layer 32 as shown in FIG. 7 may be in contact with the polymer film 20 for sealing.

  FIG. 10 is a horizontal sectional view of a unit battery 101 including the separator 1 according to another embodiment. As shown in the figure, in one separator 1 of the unit battery 101, the cross section of the seal protrusion may be trapezoidal so that the seal protrusion is in surface contact with the polymer film 20. In addition, as shown in FIG. 11, in both separators 1 of the unit battery 101, the cross section of the seal protrusion may be trapezoidal so that the seal protrusion is in surface contact with the polymer film 20.

  Next, the manufacturing method of the separator 1 is demonstrated. The manufacturing method of the separator 1 mainly includes the following six steps.

(1) Metal thin plate treatment process The sheet-like metal thin plate is treated to obtain adhesion to rubber. Examples of the processing method include the above-described surface roughening treatment and the treatment of forming an adhesive layer.
(2) Die-cutting process A die-cutting process is performed on the surface-treated metal sheet to obtain a predetermined external shape and gas path.
(3) Rubber layer forming treatment The surface of the metal sheet that has been subjected to die cutting is coated with a liquid conductive rubber containing a conductive carbon filler or the like, or a green sheet conductive rubber is laminated. For example, polyisobutylene rubber is used as the liquid conductive rubber.
(4) Highly conductive layer forming treatment A mixture or blend of carbon and binder resin is applied to the surface of the rubber layer. In addition, you may apply | coat to the inner surface of a metal mold | die beforehand at the time of the following press work process instead of apply | coating to the surface of a rubber layer.
(5) Pressing process In order to form the flow path groove of the separation part 13 and the seal protrusion part of the seal part 14, press work is performed. The separation part 13 and the seal part 14 can be formed simultaneously by pressing.
(6) Vulcanization treatment The rubber layer is vulcanized by heating. In addition, you may make it perform simultaneously the BH (Baked Hardening) process of a metal thin plate, and the vulcanization process of a rubber layer by heating at the time of press work. By subjecting the metal thin plate to BH treatment, it is possible to improve heat resistance, reduce stress relaxation of the seal portion 14, and maintain sealing performance.

  In addition to vulcanization (primary vulcanization) by heating at the time of pressing, secondary vulcanization may be performed by dielectric heating (microwave heating) using electromagnetic waves after demolding from the press mold. The dielectric heating is heating by heat generated by dielectric loss of the object to be heated. In the present invention, the rubber layer is heated by using the metal thin plate 30 as the core material of the separator 1 as the object to be heated. Thereby, the time required for the heat treatment of the rubber layer can be greatly shortened.

  A predetermined number of separators 1 and fuel cells 2 obtained as described above are alternately arranged, current collector plates 3 and insulating sheets 4 are arranged outside them, and are sandwiched and fixed by end flanges 5 to thereby fix PEFC100. Is obtained.

1 is a perspective view schematically showing a polymer electrolyte fuel cell (PEFC) 100 in a developed state. FIG. It is a horizontal sectional view of unit cell 101 including separator 1 which is a 1st embodiment of the present invention. It is a figure explaining the shape of the seal part 14 for a spring force to generate | occur | produce. It is a principal part enlarged view of the isolation | separation part 13 in 1st Embodiment. It is a principal part enlarged view of the seal part 14 in 1st Embodiment. It is a principal part enlarged view of the isolation | separation part 13 in 2nd Embodiment. It is a principal part enlarged view of the seal part 14 in 2nd Embodiment. It is a principal part enlarged view of the isolation | separation part 13 in 3rd Embodiment. It is a principal part enlarged view of the isolation | separation part 13 in 4th Embodiment. It is a horizontal sectional view of unit battery 101 including separator 1 which is other embodiments. It is a horizontal sectional view of unit battery 101 including separator 1 which is other embodiments.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Separator 2 Fuel cell 3 Current collector plate 4 Insulation sheet 5 End flange 6 Hydrogen gas supply port 7 Cooling water supply port 8 Oxygen gas supply port 9 Hydrogen gas discharge port 10 Cooling water discharge port 11 Oxygen gas discharge port 12 Electrode wiring 13 Separation part 14 Seal part 15 Separation block 16 Hydrogen gas flow path 17 Oxygen gas flow path 18 Bottom part 20 Polymer membrane 21 Catalytic electrode 30 Metal thin plate 31, 33 Rubber layer 32, 34 High conductive layer 100 Solid polymer fuel cell (PEFC) )
101 unit battery

Claims (6)

A separator interposed between a plurality of electrolyte assemblies provided with catalyst electrodes on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium,
Having a separation part for separating the flow paths of the fuel gas and the oxidant gas;
In the separation part, a rubber layer is formed on the surface of the flat metal plate that is the core material,
A separator, wherein the rubber layer is provided with the flow path.   The separator according to claim 1, wherein a highly conductive layer having conductivity higher than that of the rubber layer is formed on the surface of the rubber layer.   The separator according to claim 2, wherein the highly conductive layer is formed in a region where at least the rubber layer is in contact with the electrolyte assembly. A separator interposed between a plurality of electrolyte assemblies provided with catalyst electrodes on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium,
Having a separation part for separating the flow paths of the fuel gas and the oxidant gas;
In the separation part, a highly conductive layer having conductivity higher than the conductivity of the rubber layer and the rubber layer is formed on the surface of the flat metal plate as the core material,
A separator characterized in that the flow path is provided in a highly conductive layer. Provided on the outer periphery, having a seal portion that prevents leakage of fuel gas and oxidant gas,
The seal portion is a seal protrusion formed by forming a rubber layer on the surface of the metal plate and extending in parallel to the catalyst electrode forming surface of the electrolyte assembly, so that the top thereof is pressed against the electrolyte assembly by a spring force. The separator according to any one of claims 1 to 4, wherein the separator has a configured projecting protrusion.   The separator according to claim 1, wherein the separation portion and the seal portion are integrally formed by pressing.

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