JP2006054058A - Separator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separator which can reduce the number of members of a fuel cell and shorten a production process. <P>SOLUTION: The separator is made of a metal thin sheet 30. A polymer elastic layer 40 is provided at the part contacting a polymer film 20 of a seal protrusion of a seal part 14, and the elastic layer 40 contacts the polymer film 20 to seal it. It is preferable for a seal line direction width W of the elastic layer 40 to be 1 to 10 mm, and further preferable for it to be 2 to 7 mm. And it is preferable that a layer thickness of the elastic layer 40 is 1 to 100 μm, and further preferable that a thickness thereof is 2 to 50 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing 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. In addition, 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.

  Synthetic resins are also used, and thermosetting resins such as phenol resins and epoxy resins are used. Synthetic resins are mainly characterized by low cost, but 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.

  Patent Document 2 discloses a fuel cell separator. In this fuel cell separator, ribs are formed on the peripheral edge portion, and the rigidity when sandwiched between the seal members is increased to suppress warpage.

  Patent Document 3 discloses a fuel cell separator. The separator for a fuel cell includes a first resin layer having a volume resistivity of 1.0 Ω · cm or less and a volume resistivity of a first resin layer mixed on at least one surface of a metal substrate with a resin and a conductive filler. A smaller second resin layer is provided to improve current collecting performance, moldability, strength, and corrosion resistance.

JP-A-8-180883 JP 2002-175818 A JP 2003-297383 A

  In the conventional separator, the outer peripheral portion is sealed with a sealing material such as an O-ring so that hydrogen gas, oxygen gas, cooling water and the like do not leak.

  Further, as shown in Patent Document 1 and Patent Document 2, in order to prevent the reaction gas and the cooling fluid from leaking out, a gasket is provided on the periphery of the separator.

  Thus, in the conventional fuel cell, it is necessary to form a sealing material between the separator and the cell at the outer peripheral portion. Further, as a manufacturing process, after the separator is processed and formed, a process of pasting the sealing material on the outer peripheral portion of the separator or a process of molding the sealing material in the mold with the separator as a core is required.

  The objective of this invention is providing the separator which can reduce the number of members of a fuel cell, and can shorten a manufacturing process.

The present invention is provided between a plurality of electrolyte assemblies each provided with a catalyst electrode on the surface in the thickness direction of an electrolyte layer containing an electrolyte medium, and separating a fuel gas and an oxidant gas flow path; A separator integrated with a seal portion provided to prevent leakage of fuel gas and oxidant gas,
The region corresponding to the seal portion is a seal protrusion that extends in parallel with the catalyst electrode forming surface of the electrolyte assembly, and the top portion of the seal protrusion is pressed against the electrolyte assembly by a spring force. It is a separator characterized by having.

The present invention is characterized by comprising a metal plate.
The present invention is also characterized in that a polymer elastic layer made of an elastic body is provided at least in a portion where the seal projection comes into contact with the electrolyte layer.

  In the invention, it is preferable that the polymer elastic layer has a width of 1 to 10 mm and a thickness of 1 to 100 μm.

  Further, the present invention is characterized in that there are two or more seal protrusions, and contact lines that virtually indicate contact points between the top portions of the seal protrusions and the electrolyte layer are parallel to each other.

  Further, the present invention has an auxiliary protrusion configured in the same manner as the seal protrusion in a region other than the seal part and the separation part, and the auxiliary protrusion is formed with the electrolyte assembly during assembly of the fuel cell including the separator. It is characterized in that the surface pressure generated between the two is uniformly distributed.

  According to the present invention, the separator interposed between the plurality of electrolyte assemblies provided with the catalyst electrodes on the surface in the thickness direction of the electrolyte layer containing the electrolyte medium, and separating the flow path of the fuel gas and the oxidant gas; This is a separator integrated with a seal portion provided in the portion and preventing leakage of fuel gas and oxidant gas.

  The separator is made of a metal plate, and a region corresponding to the seal portion is a seal protrusion that extends in parallel to the catalyst electrode forming surface of the electrolyte assembly, and the top portion thereof is pressed against the electrolyte assembly by a spring force. It has the seal | sticker protrusion comprised in this.

  This eliminates the need for sealing members such as O-rings and gaskets, which have been conventionally required, and reduces the number of fuel cell members and shortens the manufacturing process.

According to the invention, the polymer elastic layer made of an elastic body is provided at least in a portion where the seal protrusion comes into contact with the electrolyte layer.
Thereby, the sealing performance is further improved by providing the polymer elastic layer which is an elastic body.

  According to the invention, the polymer elastic layer has a width of 1 to 10 mm and a thickness of 1 to 100 μm.

  Thereby, sufficient sealing performance can be obtained even if the region where the polymer elastic layer is provided is a smaller region.

According to the present invention, there are two or more seal protrusions, and the contact lines that virtually indicate the contact points between the tops of the seal protrusions and the electrolyte layer are parallel to each other.
Thereby, a sealing performance can be further improved.

  According to the present invention, the auxiliary projection having the same configuration as the seal projection is provided in a region other than the seal portion and the separation portion, and the auxiliary projection is formed in the electrolyte assembly when the fuel cell including the separator is assembled. The surface pressure generated between the three-dimensional object is provided so as to be uniformly distributed.

  Thereby, the poor contact etc. which arise between a separator and an electrolyte assembly by tilting a separator at the time of an assembly, etc. can be prevented.

  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 between 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. 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.

A 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 allows hydrogen ions (protons) to pass therethrough, and a perfluorosulfonic acid resin membrane (for example, 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 this embodiment, the catalyst electrode 21 is not formed on the entire surface of the polymer film 20, but the polymer film 20 is exposed on the surface over an outer peripheral width of 1 to 20 mm, preferably 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 14 is formed in a region facing the region where the polymer film 20 is exposed.

  As a main material of the separator 1, a flat metal thin plate is used. 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 preferred. As for the stainless steel plate, a surface-treated one can be used. For example, a surface pickled, electrolytically etched, containing conductive inclusions, formed with a BA film, or coated with a conductive compound by ion plating can be used. Further, a highly corrosion-resistant stainless steel plate with an ultrafine crystal structure can be used.

  The separating portion 13 and the seal portion 14 can be integrally formed by subjecting the metal thin plate as described above to plastic deformation processing, for example, press processing. In addition, in order to improve heat resistance, what performed the BH (Baked Hardening) process after press work is preferable.

  The separation portion 13 is formed with a plurality of flow channel grooves parallel to each other and parallel to the formation surface of the catalyst electrode 21. This channel groove has a concave shape in a cross section perpendicular to the gas flow direction. The channel groove is composed of the separation wall 15 and the electrode contact wall 16, and the space surrounded by the separation wall 15, the electrode contact wall 16 and the catalyst electrode 21 becomes the hydrogen gas channel 17 and the oxygen gas channel 18. The separation wall 15 separates the hydrogen gas channel 17 and the oxygen gas channel 18 so that hydrogen gas and oxygen gas are not mixed. The electrode contact wall 16 is in contact with the catalyst electrode 21, takes out DC power generated at the interface between the polymer membrane 20 and the catalyst electrode 21 as DC current, and collects it through the separation wall 15, another electrode contact wall 16, and the like. Collected on the electric board.

  The channel grooves adjacent to each other are formed so that the open surfaces are opposite to each other, and accordingly, the hydrogen gas channel 17 and the oxygen gas channel 18 are set to be adjacent to each other. 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 17, and the other is an oxygen gas flow path 18.

  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.

  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. The top 19 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. In addition, by forming the seal protrusion in an inverted U shape or an inverted V shape, the membrane contact area of the top portion 19 is reduced, and a high-pressure seal similar to an O-ring is realized.

  In order to press-contact the top 19 of the seal protrusion against the polymer film 20 by a spring force, the position of the top 19 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, when the PEFC 1 is assembled, the position of the top 19 of the seal protrusion is determined based on the virtual contact surface A with the catalyst electrode 21. The distance between the contact surface and the top portion 19 is a position where the thickness t1 of the catalyst electrode 21 is obtained. Therefore, in a state before the PEFC 1 is assembled, as shown in FIG. 3B, the position of the top portion 19 of the seal projection is such that the distance from the contact surface with the catalyst electrode 21 is t2 larger than t1. What is necessary is just to form. Since the connecting portion between the separation portion 13 and the seal protrusion acts as a spring, the pressure when the top portion 19 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. Therefore, the seal pressure can be easily adjusted by changing t2 at the time of press work 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 symmetry, the pressure contact position by the top portion 19 is also plane-symmetric with the center of the fuel cell 2 as the plane of symmetry. It becomes a relationship. Since the pressure contact position of the top portion 19 is a facing position, the sealing performance is improved. Note that the stress relaxation of the seal portion 14 can be reduced and the sealing performance can be maintained by the above-described BH treatment.

  FIG. 4 is a schematic view of the unit battery 101 as viewed from the side. The separation part 13 is provided in the center part, and the seal part 14 is provided in the outer peripheral part. In FIG. 4, detailed shapes of the separation portion 13 and the seal portion 14 are omitted. In the seal portion 14, the top portion 19 of the seal protrusion is in contact with the polymer film 20, and the seal line L, which is a contact line virtually showing the contact portion, surrounds the separation portion 13, so that hydrogen gas and oxygen Prevents gas leakage.

  Furthermore, as shown in the horizontal sectional view of FIG. 2, the sealing portion is further improved by sealing the outer peripheral top portion 19a in contact with the adjacent fuel cell, in addition to the top portion 19 of the sealing protrusion. The seal line by the top portion 19 a is parallel to and adjacent to the seal line by the top portion 19.

  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 is made of a thin metal plate 30, and in the seal portion 14, a polymer elastic layer 40 is provided in a portion of the seal protrusion that contacts the polymer film 20, and the polymer elastic layer 40 is a polymer. The membrane 20 contacts and is sealed.

  As a result, the sealing performance is further improved, and sealing members such as O-rings and gaskets, which have been conventionally required, are not required, the number of members of the fuel cell can be reduced, and the manufacturing process can be shortened.

  Further, the sealing protrusion provides an effect that the sealing function is exhibited even if the polymer elastic layer 40 is a thin layer, and the amount of stress relaxation is extremely low.

  The width W in the seal line direction of the polymer elastic layer 40 is preferably 1 to 10 mm, more preferably 2 to 7 mm. Moreover, 1-100 micrometers is preferable and, as for layer thickness t, More preferably, it is 2-50 micrometers. By providing the polymer elastic layer 40 in such a region, a sufficient sealing property can be obtained even in a smaller region.

  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 of the seal projection is deformed. There is a risk of fluid leaking out. When the polymer elastic layer 40, which is an elastic body, is provided in the seal portion 14, the contact portion is deformed by the pressure contact of the top portion 19 by the spring force, and no gap is formed between the surface of the polymer film 20 and the seal portion 14 is sealed. Improves.

  The polymer elastic layer 40 is made of rubber or a synthetic resin. Examples of rubber include general-purpose rubbers such as isoprene rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene rubber, fluorine rubber, silicone rubber, and nitrile rubber. Epichlorohydrin rubber having gas permeation resistance and heat resistance can be used. In particular, allylic addition polymerization type polyisobutylene having excellent heat resistance and acid resistance is preferable.

  Moreover, as a synthetic resin, an epoxy resin, a urethane-acrylate resin, a polyamide resin, a silicone 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) and the like are preferable.

  The polymer elastic layer 40 is roughened by, for example, oxidizing the metal thin plate 30 and adhered by an anchor effect, or a resin adhesive such as phenol resin, resorcin resin, silicone resin and polyurethane, polyimide, polyamide To reduce brittleness in heat-resistant structural adhesives such as imide, polybenzimidazole, and polyoxadiazole, instantaneous adhesives such as α-cyanoacrylate, and thermosetting resins (epoxy resins, phenol resins, etc.) An adhesive such as nylon-epoxy resin or nylon-phenol resin mixed with thermoplastic resin (nylon, acetal resin, etc.) or elastomer (nitrile rubber, silicone rubber, etc.) may be used.

  The polymer elastic layer 40 does not need to be bonded to the metal thin plate 30 and may be appropriately selected depending on the required conditions such as low adhesion, adhesion, weak adhesion, and strong adhesion. Even with a low degree of adhesion, a sufficient sealing function is exhibited if the tightening surface pressure is appropriate. However, when a pressure equal to or higher than the tightening surface pressure is applied from the lateral direction with respect to the tightening direction, the polymer elastic layer 40 may be laterally displaced, dropped off, and the like, and surface roughening is also preferably performed.

  FIG. 6 is an enlarged view of a main part of the separation unit 13 in the first embodiment. In the separation unit 13 of the present embodiment, the metal thin plate 30 comes into contact with the catalyst electrode 21, and DC power generated at the interface between the polymer film 20 and the catalyst electrode 21 is taken out as DC current and collected through the separator 1. Collected on the electric board.

  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 metal thin plate 30 and a coating layer 31, and the coating layer 31 is formed to cover the surface of the metal thin plate 30. In the seal portion 14, a polymer elastic layer 40 is provided in a portion of the seal protrusion that contacts the polymer film 20, as in the first embodiment, and the polymer elastic layer 40 contacts the polymer film 20 and seals. is doing.

  FIG. 8 is an enlarged view of a main part of the separation unit 13 in the second embodiment. In the separation unit 13, the coating layer 31 contacts the catalyst electrode 21 and collects a direct current. Therefore, the coating layer 31 needs to have conductivity.

  As the coating layer 31, a material obtained by adding conductivity by adding a conductive filler such as a carbon filler to rubber or synthetic resin similar to the rubber or synthetic resin used for the polymer elastic layer 40 is used. In particular, allylic addition polymerization type polyisobutylene to which a carbon filler is added is preferable.

  FIG. 9 is an enlarged view of a main part of the seal portion 14 in the third embodiment. In the present embodiment, the separator 1 includes a metal thin plate 30, a coating layer 31, and an adhesive layer 32, and the coating layer 31 is formed on the surface of the metal thin plate 30 via the adhesive layer 32. When rubber or synthetic resin that does not provide sufficient adhesion due to surface roughening of the metal thin plate 30 is used as the coating layer 31, the adhesive layer 32 may be provided. In the seal portion 14, as in the first and second embodiments, a polymer elastic layer 40 is provided in a portion of the seal protrusion that contacts the polymer film 20, and the polymer elastic layer 40 contacts the polymer film 20. Seals in contact.

  FIG. 10 is an enlarged view of a main part of the separation unit 13 according to the third embodiment. In the separation unit 13, as in the second embodiment, the coating layer 31 contacts the catalyst electrode 21 and collects a direct current. Therefore, the coating layer 31 needs to have conductivity.

  As the coating layer 31, a material obtained by adding conductivity by adding a conductive filler such as a carbon filler to rubber or synthetic resin similar to the rubber or synthetic resin used for the polymer elastic layer 40 is used. In particular, allylic addition polymerization type polyisobutylene to which a carbon filler is added is preferable.

  The adhesive layer 32 is formed on the surface of the metal sheet 30 by performing coating with a conductive coupling agent typified by triazine thiols and doping treatment with a conductive polymer typified by polyanilines. It is formed as a diffusion layer. Since the triazine thiols and polyanilines diffused on the metal surface exhibit conductivity, the conductivity with the resin layer 32 can be secured and the generated DC power can be taken out as a DC current.

  FIG. 11 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. 12, 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.

  FIG. 13 is a schematic view of the unit battery 101 as viewed from the side. The separation part 13 is not necessarily provided over the entire surface of the fuel battery cell 2, and the seal line L may be biased as shown in FIG. In such a case, the distribution of the surface pressure generated between the separator 1 and the fuel cell 2 at the time of assembly is biased, resulting in poor contact at the separation portion 13. In order to prevent this, a protrusion (auxiliary protrusion) similar to the seal protrusion is provided in a region other than the seal portion 14. As shown in the figure, the auxiliary protrusions are provided so that the contact lines M and the seal lines L indicating the positions where the auxiliary protrusions contact the polymer membrane 20 are uniformly distributed in the fuel cell 2 surface. As a result, the surface pressure distribution becomes uniform.

  Next, the manufacturing method of the separator 1 is demonstrated. The manufacturing method of the separator 1 mainly includes the following 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) Coating 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-like conductive rubber is laminated. For example, polyisobutylene rubber is used as the liquid conductive rubber.

(4) Polymer elastic layer forming treatment A polymer elastic layer is provided in a region that becomes the top of the seal projection of the metal thin plate or coating layer. Specifically, there are two methods: a method using a solution obtained by dissolving a rubber or synthetic resin to be a polymer elastic layer in a solvent, and a method using a reaction solution containing a monomer or an oligomer to be rubber or a synthetic resin. is there.
Furthermore, as a method for applying these solution or reaction solution to a predetermined region, for example, a printing method such as screen printing, intaglio printing, or stencil printing can be used.

(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 polymer elastic layer and the coating layer are vulcanized by heating. In addition, you may make it perform simultaneously the BH (Baked Hardening) process of a metal thin plate, and the bridge | crosslinking 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.
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.

A separator was produced under the conditions shown in the following examples.
A thin metal plate was commonly used in each example, and a thin plate made of SUS304 having a length of 10 cm, a width of 10 cm, and a thickness of 0.2 mm was used. Further, the surface was roughened by sand blasting, a seal protrusion was formed on the outer peripheral portion by pressing, and a separation groove was formed in the central portion.

Example 1
A one-component thermosetting olefin-based sealing material (manufactured by ThreeBond Co., Ltd., trade name ThreeBond 1152) is printed by screen printing at a position to be the top of the seal protrusion. Heat curing at 120 ° C. for 40 minutes to form a polymer elastic layer having a layer thickness of 25 μm to 30 μm. After heat curing, the seal protrusion is formed by press working.

(Example 2)
A seal protrusion is formed in advance by pressing. A sealing material mixed with chlorosulfonated polyethylene, an inorganic filler, and a solvent (manufactured by ThreeBond Co., Ltd., trade name ThreeBond 1104) is printed on the top of the seal protrusion by screen printing, heat cured, and a layer thickness of 15 μm to 20 μm is high. A molecular elastic layer is formed.

(Example 3)
A seal protrusion is formed in advance by pressing. Silicone PSA, which is a photocurable adhesive material, is ejected with a needle-like nozzle on the top of the seal protrusion, and cured by light irradiation to form a polymer elastic layer having a layer thickness of 15 μm to 20 μm.

Example 4
The surface of SUS304 thin plate is roughened by sandblasting, primed with polyaniline, mixed with allyl-based addition-polymerized polyisobutylene and conductive carbon graphite at a thickness of 50μm, and cured by heating at 130 ° C for 2 hours. To form a coating layer. In the same manner as in Example 1, a one-component heat-curable olefin-based sealing material (manufactured by ThreeBond Co., Ltd., trade name ThreeBond 1152) is printed by screen printing on the top of the seal protrusion, and heated at 120 ° C. for 40 minutes. Curing is performed to form a polymer elastic layer having a layer thickness of 25 μm to 30 μm. After heat curing, a seal projection is formed by press working.

(Example 5)
The surface of SUS304 thin plate is roughened by sandblasting, primed with polyaniline, mixed with allyl-based addition-polymerized polyisobutylene and conductive carbon graphite at a thickness of 50μm, and cured by heating at 130 ° C for 2 hours. To form a coating layer. A seal projection is formed by pressing. A sealing material mixed with chlorosulfonated polyethylene, an inorganic filler, and a solvent (manufactured by ThreeBond Co., Ltd., trade name ThreeBond 1104) is printed on the top of the seal protrusion by screen printing, heat cured, and a layer thickness of 15 μm to 20 μm is high. A molecular elastic layer is formed.

(Comparative example)
A flow path groove is formed in the SUS304 thin plate by press working. At this time, no seal protrusion is formed. A polyisobutylene-based flat sheet gasket having a thickness of 1 mm is provided in a portion corresponding to the outer peripheral portion where the seal protrusion is formed in the above embodiment.
Seal tests were conducted on Examples 1 to 5 and Comparative Examples. In the seal test, four separators are stacked, sandwiched between 10 mm thick steel plates, and tightened in the stacking direction with bolts. Air was injected from an injection hole provided in the separation part, and the presence or absence of leakage was examined.
In Examples 1 to 5, there was no air leakage and good sealing performance was shown. On the other hand, air leakage occurred in the comparative example.

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

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 wall 16 Electrode contact wall 17 Hydrogen gas flow path 18 Oxygen gas flow path 19, 19a Top part 20 Polymer film 21 Catalyst electrode 30 Metal thin plate 31 Coating layer 32 Adhesion layer 40 Polymer elastic layer 100 Solid high Molecular fuel cell (PEFC)
101 unit battery

Claims (6)

A separator disposed between a plurality of electrolyte assemblies each provided with a catalyst electrode on a surface in a thickness direction of an electrolyte layer containing an electrolyte medium, separating a flow path of a fuel gas and an oxidant gas; A separator integrated with a seal portion that prevents leakage of gas and oxidant gas,
The region corresponding to the seal portion is a seal protrusion that extends in parallel with the catalyst electrode forming surface of the electrolyte assembly, and the top portion of the seal protrusion is pressed against the electrolyte assembly by a spring force. The separator characterized by having.   The separator according to claim 1, comprising a metal plate.   The separator according to claim 1 or 2, wherein a polymer elastic layer made of an elastic body is provided at least in a portion where the seal projection comes into contact with the electrolyte layer.   The separator according to any one of claims 1 to 3, wherein the polymer elastic layer has a width of 1 to 10 mm and a thickness of 1 to 100 µm.   The contact line which has two or more said seal protrusions, and shows the contact location of the top part and electrolyte layer of each seal protrusion is mutually parallel, The one of Claims 1-4 characterized by the above-mentioned. The separator according to one.   A region other than the seal portion and the separation portion has an auxiliary protrusion configured in the same manner as the seal protrusion, and the auxiliary protrusion is a surface generated between the electrolyte assembly when the fuel cell including the separator is assembled. The separator according to any one of claims 1 to 5, wherein the separator is provided so that the pressure is uniformly distributed.

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