FUEL CELL AND METHOD FOR MANUFACTURING THE FUEL CELL

Abstract

Fuel cell with a plurality of stacked unit cells (100), wherein the unit cells (100) each have: a membrane electrode arrangement (10) with an electrolyte membrane (12) on whose two surfaces electrodes (14, 16) are formed; a pair of gas separators (40, 50) comprising a gas separator (50) provided on the side of a first surface of the membrane electrode arrangement (10) and a gas separator (40) provided on the side of a second surface of the membrane electrode arrangement (10); and a first sealing section (24, 26, 27) which is provided outside an outer circumference of the membrane electrode arrangement (10) between the pair of gas separators (40, 50), wherein the fuel cell also features: a second sealing section (60, 62) which is provided between adjacent unit cells (100); a first distributor (31, 33, 34, 36) in which reaction gas flows, wherein the first distributor (31, 33, 34, 36) is formed through the fuel cell in a stacking direction of the unit cells (100) and is connected to a cell-internal gas flow path through which the reaction gas flows between the membrane electrode arrangement (10) and the gas separator (40, 50); and a second distributor (32, 35) in which a coolant flows, wherein the second distributor (32, 35) is formed through the fuel cell in the stacking direction of the unit cells (100) and is connected to an inter-cell coolant flow path in which the coolant flows between adjacent unit cells (100), wherein one section of the first sealing section (24, 26, 27) and the second sealing section (60, 62) comprises adhesive sealing sections which adhere to the two gas separators (40, 50) in contact with one section of the first sealing section (24, 26, 27) and the second sealing section (60, 62), and the other section of the first sealing section (24, 26, 27) and the second sealing section (60, 62) comprises seals, and wherein one of the seals (60) and one of the adhesive sealing sections (26) are arranged in this order starting from one side closer to the first distributor (31, 33, 34, 36) and / or the second distributor (32, 35) when the fuel cell is viewed in the stacking direction, wherein one of the seals (60) and one of the adhesive sealing sections (26) are provided along an outer circumference of the first distributor (31, 33, 34, 36) and / or the second distributor (32, 35).

Description

Background area

[0001] The present disclosure relates to a fuel cell and a method for manufacturing the fuel cell. Related state of the art

[0002] Fuel cells are generally manufactured by stacking a plurality of unit cells, each prepared by sandwiching an element including a membrane electrode assembly with or between a pair of gas separators. The membrane electrode assembly includes an electrolyte membrane having a surface on which an electrode is formed. One conventional method for manufacturing such a fuel cell that has been proposed involves heating and curing the entire sealing element provided between a pair of gas separators sandwiching a membrane electrode assembly therebetween to ensure sealing performance for the interior of the unit cell (see, for example, JP 2014-238997 A). Other membrane electrode assemblies are the subject of US 2015 / 0 188 152 A1, DE 10 2012 205 644 A1, and US 2017 / 0 229 718 A1.

[0003] However, this configuration, in which the interior of the unit cell is sealed by heating and curing the sealing member provided between the gas separators as described above, requires a long period of time for curing. Therefore, high manufacturing process efficiency, that is, higher productivity, is demanded. The present inventors investigated a method of bonding a sealing member provided between gas separators and the gas separators to each other by hot pressing in order to improve the productivity of a process for providing the sealing member between the gas separators. As a result, the inventors found a problem in a sealing structure for a manifold and a fluid flow path in or between the unit cells formed by such a method.In particular, the sealing element and the gas separators, which have been connected to each other, absorb a release force due to the pressure of a fluid flowing in the distributor, which may lead to insufficient durability of the seal. Summary

[0004] The present disclosure is intended to solve the problems described above and can be implemented with the following aspects.

[0005] (1) One aspect of the present disclosure provides a fuel cell comprising a plurality of stacked unit cells. The unit cells each include: a membrane electrode assembly having an electrolyte membrane on both surfaces of which electrodes are formed; a pair of gas separators including a gas separator provided on a first surface side of the membrane electrode assembly and a gas separator provided on a second surface side of the membrane electrode assembly; and a first sealing portion provided outside an outer periphery of the membrane electrode assembly between the pair of gas separators.The fuel cell further includes: a second sealing portion provided between adjacent ones of the unit cells; a first manifold in which reaction gas flows, the first manifold being formed through the fuel cell in a stacking direction of the unit cells and communicating with an intra-cell gas flow path through which the reaction gas flows between the membrane electrode assembly and the gas separator; and a second manifold in which a coolant flows, the second manifold being formed through the fuel cell in the stacking direction of the unit cells and communicating with an inter-cell coolant flow path in which the coolant flows between adjacent ones of the unit cells.One of the first sealing portion and the second sealing portion includes adhesive sealing portions that adhere to the two gas separators in contact with the one of the first sealing portion and the second sealing portion, and another of the first sealing portion and the second sealing portion includes gaskets, and one of the gaskets and one of the adhesive sealing portions are arranged in this order from a side closer to the first manifold and / or the second manifold when the fuel cell is viewed in the stacking direction, wherein the one of the gaskets and the one of the adhesive sealing portions are provided along an outer periphery of the first manifold and / or the second manifold.

[0006] In the fuel cell according to this aspect, the gasket provided closer to the manifold than the adhesive seal portion can prevent peeling of the adhesive seal portion and improve the durability of the seal in the fuel cell. Furthermore, the provided gasket portion allows for a simple bonding or bonding process, thereby enabling the fuel cell to be manufactured with efficient processes and improving productivity.

[0007] (2) In the fuel cell according to the aspect, the second sealing portion may include a coolant sealing portion configured to seal the inter-cell coolant flow path and a gas sealing portion configured to seal the first manifold, and the coolant sealing portion may be formed to surround an outer side of the gas sealing portion when the fuel cell is viewed in the stacking direction. In the fuel cell according to this aspect, even if leakage occurs from the gas sealing portion, the coolant flow path in which the coolant flows and the coolant sealing portion can prevent the reaction gas from leaking out of the fuel cell.

[0008] (3) In the fuel cell according to the aspect, the unit cells may each further include a resin frame connected to an outer periphery of the membrane electrode assembly between the pair of gas separators, wherein the first manifold and the second manifold may be formed by portions in which the resin frame and the gas separator are stacked, wherein the first sealing portion may correspond to the adhesive sealing portion, and the adhesive sealing portion may correspond to a part of the resin frame. In the fuel cell according to this aspect, the first sealing portion serving as the adhesive sealing portion may be formed using the resin frame connected to the outer periphery portion of the membrane electrode assembly.

[0009] (4) In the fuel cell according to the aspect, another of the gaskets and another of the adhesive seal portions may be arranged in this order from the side closer to the electrode when the fuel cell is viewed in the stacking direction, and the other of the gaskets and the other of the seal portions are provided at positions along the outer circumference of the electrode. In the fuel cell according to this aspect, the gasket can prevent the adhesive seal portion from peeling off due to pressure in a flow path formed in a region overlapping with the electrode in the stacking direction.

[0010] The present disclosure can be implemented in various aspects other than those described above, and can be implemented in aspects such as a method for manufacturing a fuel cell, a unit cell for a fuel cell, a method for manufacturing a unit cell, and a method for arranging a seal portion in a fuel cell. Short description of the figures Fig. 1 is an exploded perspective view showing a schematic configuration of a unit cell. Fig. Figure 2 is a schematic sectional view showing a schematic configuration of the unit cell. Fig. 3 is a plan view of a gas separator. Fig. Figure 4 is a schematic cross-sectional view showing a schematic configuration of the unit cell. Fig. 5 is a cross-sectional view schematically illustrating a state in which the unit cells are stacked. Fig. Figure 6 is a diagram illustrating the steps in a method for manufacturing a fuel cell. Fig. 7 is a cross-sectional view schematically illustrating step S150. Detailed description A. Overall configuration of the fuel cell

[0011] Fig. 1 is an exploded perspective view illustrating a schematic configuration of a cell (unit cell) 100 in a fuel cell according to a first embodiment of the present disclosure. Fig. Fig. 2 is a schematic sectional view illustrating a schematic configuration of the unit cell 100. A configuration of the fuel cell according to the present embodiment will be described below with reference to Fig. 1 and Fig. 2. The Fig. 1 and Fig. 2 and other figures described later schematically illustrate the configurations of components of the fuel cell according to the present embodiment, so that the size of each component shown in the figure does not represent a specific size.

[0012] The fuel cell according to the present embodiment has a stacked structure with a plurality of stacked unit cells 100. The fuel cell according to the present embodiment is a polymer electrolyte fuel cell, but may also correspond to other types of fuel cells, such as a solid oxide fuel cell.

[0013] The unit cell 100 includes a membrane electrode assembly 10 (hereinafter referred to as an MEA 10), gas diffusion layers 15 and 17, gas separators 40 and 50, and a resin frame 25. As shown in Fig. As shown in Figure 2, the MEA 10 includes an electrolyte membrane 12, an anode 14, and a cathode 16, which correspond to catalyst electrode layers formed on surfaces of the electrolyte membrane 12. The MEA 10 is sandwiched by gas diffusion layers 15 and 17. The structure in which the gas diffusion layers 15 and 17 are stacked on the MEA 10 is also referred to as a membrane electrode gas diffusion layer assembly (MEGA) 18. The resin frame 25 is bonded to an outer peripheral portion of the MEA 10. The structure in which the resin frame 25 is bonded to the MEA 10 is also referred to as a cell frame assembly 20. In the present embodiment, the cell frame assembly 20 includes the gas diffusion layers 15 and 17. The cell frame assembly 20 is sandwiched by the gas separators 40 and 50 from both sides.The gas separator 50 has a surface opposite the surface connected to the cell frame assembly 20 and is provided with a seal. Note that in addition to this seal, which is shown in . Fig. 2 is shown as a seal 62, further a seal 60 is provided on the gas separator 50, as described later (see Fig. 4). Seals 60 and 62 seal a fluid flow path between adjacent unit cells 100 (hereinafter also referred to as "between cells"). The arrangement of seals 60 and 62 will be described in detail later.

[0014] The electrolyte membrane 12 is a polymer electrolyte material (a proton-conducting ion exchange membrane made of, for example, fluororesin) that exhibits excellent proton conductivity in a wet state. The anode 14 and the cathode 16 each correspond to a porous element having pores, and these are formed by coating conductive particles (e.g., carbon particles) supporting a catalyst such as platinum or a platinum alloy with a polyelectrolyte having proton conductivity. The polyelectrolyte of the anode 14 and the cathode 16 may comprise a polymer of a type that is the same as or different from that of the polyelectrolyte of the electrolyte membrane 12.

[0015] The gas diffusion layers 15 and 17, which correspond to elements having gas permeability and electron conductivity, may be formed of a metallic element such as foam metal or a metallic fabric, or a carbon element such as a carbon fabric or carbon paper.

[0016] The gas separators 40 and 50 are rectangular, plate-shaped elements. The gas separators 40 and 50 correspond to gas-impermeable, conductive elements, such as carbon elements such as polymer electrolytic dense carbon with gas impermeability, which is obtained by densifying carbon, or metal elements such as press-formed stainless steel. Flow path grooves 28 and 29, through which reaction gas supplied for an electrochemical reaction flows, are formed on surfaces of the gas separators 40 and 50 facing the MEGA 18. The flow path groove 28 forms an intra-cell fuel gas flow path in which fuel gas including hydrogen flows between the gas separator 40 and the anode 14. The flow path groove 29 forms an internal cell oxidation gas flow path in which oxidation gas including oxygen flows between the gas separator 50 and the cathode 16. In Fig. 1, a recessed and protruding shape are omitted from the flow path grooves 28 and 29 formed on the surfaces of the gas separator 40 and the gas separator 50. Porous members for forming the intra-cell gas flow path may be formed between the gas separators 40 and 50 and the gas diffusion layers 15 and 17. In such a case, the flow path grooves 28 and 29 may be omitted.

[0017] The resin frame 25 is formed using resin, such as thermoplastic resin, and molded to have a rectangular, frame-shaped outer shape. The resin frame 25 has an opening 25a in the center, which serves as a holding or receiving area for the MEA 10 (MEGA 18). As shown in Fig. 1, the resin frame 25 is provided with a plurality of slots 39, which will be described in more detail later.

[0018] Examples of the material of the resin frame 25 may be modified polyolefin, such as modified polypropylene, which is provided with adhesiveness by introducing a functional group (e.g., ADMER (registered trademark), manufactured by Mitsui Chemicals, Inc.). The resin frame 25 and the gas separators 40 and 50 are bonded or adhered to each other by hot pressing. Fig. 2 illustrates an adhesive sealing portion 27 as an example of a portion where the gas separators 40 and 50 and the resin frame 25 are bonded together by hot pressing. When the resin frame 25 is formed by modified polyolefin imparted with adhesiveness, the resin frame 25 and the gas separators 40 and 50 can be easily bonded together by hot pressing. When the resin frame 25 is formed of resin without any particular adhesiveness, the resin frame 25 may have a surface provided with a layer of an adhesive that exerts adhesiveness by hot pressing. The resin frame 25 used in such a case may be formed of resin selected from polypropylene (PP), phenolic resin, epoxy resin, polyethylene terephthalate (PET), and polyethylene naphthalate (PEN). The adhesive layer provided on the surface of the resin frame 25 may comprise, for example, a silane coupling agent.In the present embodiment, the adhesion between the resin frame 25 and the gas separators 40 and 50 indicates that a hydrogen bond or covalent bond is formed as a result of a chemical reaction between the surface of the resin frame 25 and the surfaces of the gas separators 40 and 50 by hot pressing. The portions of the resin frame 25 that adhere to the gas separators 40 and 50 seal the interior of the unit cell 100. The arrangement of the portions where the resin frame 25 and the gas separators 40 and 50 are bonded will be described in detail later. An aspect of the connecting portion between the resin frame 25 and the MEA 10 (MEGA 18) will also be described in detail below.

[0019] As described above, the gaskets 60 and 62 are provided on the surface of the gas separator 50 and seal a flow path (inter-cell coolant flow path) formed between the gas separator 50 of one of the adjacent unit cells 100 and the gas separator 40 of the other of the adjacent unit cells 100 when a plurality of unit cells 100 are stacked. The gaskets 60 and 62 may each be formed of an elastic material such as rubber or thermoplastic elastomer. The surface of the gas separator 50 on which the gaskets 60 and 62 are formed is also referred to as a first surface, and the surface of the gas separator 50 opposite to the first surface and intended to contact the resin frame 25 where the adhesive seal portion 27 is formed is also referred to as a second surface.The first surface can be considered to be opposite to the surface of the gas separator 50 on which the MEA 10 is provided.

[0020] Each of manifold holes 31 to 36 for forming a manifold is formed at positions of the gas separators 40 and 50 and the resin frame 25 close to the outer periphery, and these overlap each other in a stacking direction of elements including the MEA 10 and the gas separators 40 and 50 (the stacking direction of the unit cell 100, which is also simply referred to as a stacking direction). Thus, in the fuel cell, the manifold is formed by a portion where the gas separators 40 and 50 and the resin frame 25 are stacked. The manifold corresponds to a flow path through which reaction gas or a coolant flows, is formed through the fuel cell in the stacking direction, and communicates with the intra-cell gas flow path formed in the unit cell 100 or the inter-cell coolant flow path formed between the adjacent unit cells 100.Specifically, manifold holes 31 and 36 form an oxidizing gas manifold through which the oxidizing gas is supplied to or discharged from the intra-cell oxidizing gas flow path. Manifold holes 33 and 34 form a fuel gas manifold through which fuel gas is supplied to or discharged from the intra-cell fuel gas flow path. Manifold holes 32 and 35 form a coolant manifold through which coolant is supplied to and discharged from the inter-cell coolant flow path. The oxidizing gas manifold and the fuel gas manifold are also referred to as a first manifold, and the coolant manifold is also referred to as a second manifold. B. Arrangement of the sealing section:

[0021] Fig. 3 is a plan view of the gas separator 50. Fig. 4 is a schematic cross-sectional view illustrating a schematic configuration of the unit cell 100. Fig. 5 is a cross-sectional view schematically illustrating a state in which the unit cells 100 are stacked. Fig. 2, as described above, is a sectional view taken along the line 2-2 in Fig. 3, and Fig. 4 is a cross-sectional view taken along line 4-4 in Fig. 3. Fig. 5, which is a cross-sectional view similar to Fig. 4 represents a state in which two unit cells 100 are stacked as an example of the stacking of the unit cells 100.

[0022] In Fig. 3, a Z direction represents the stacking direction, and X and Y directions represent two directions perpendicular to the stacking direction, parallel to the plane of the gas separator 50, and perpendicular to each other. As described above, the six distribution holes 31 to 36 are formed in the gas separator 50. The distribution holes 31 to 33 are formed along one of two sides extending in the Y direction out of the four sides defining the outer periphery of the gas separator 50, and the distribution holes 34 to 36 are formed along the other of the two sides extending in the Y direction.

[0023] As in Fig. 4, the unit cell 100 includes the seals 60 and 62. The seals 60 and the seals 62 are provided at corresponding positions on the unit cells 100. Thus, the seals 60 and the seals 62 of the unit cells 100 overlap each other in the stacking direction when the unit cells 100 are stacked, as shown in Fig. 5 is shown. In Fig. In Figure 5, dashed lines extending in the stacking direction indicate the overlap of the seals 60 and 62 in the stacking direction. The seals 60 and 62 seal the inter-cell fluid flow path by a reaction force generated in the seals 60 and 62 by lips (distal end portions of the seals 60 and 62) contacting the gas separator 40 of the adjacent unit cells 100, thus exerting a compressive force in the stacking direction. Such a sealing portion formed by the seals 60 and 62 in the present embodiment, that is, the sealing portion provided between the unit cells 100, is also referred to as a "second sealing portion."

[0024] As in Fig. As shown in Figure 4, the resin frame 25 of the unit cell 100 is provided with adhesive seal portions 26 and the adhesive seal portions 27, which are formed by bonding the resin frame 25 and the gas separators 40 and 50 together. The adhesive seal portions 26 and the adhesive seal portions 27 are provided at corresponding positions of the unit cells 100. Thus, the adhesive seal portions 26 and the adhesive seal portions 27 of the unit cells 100 are arranged to overlap each other in the stacking direction when the unit cells 100 are stacked, as shown in Figure 4. Fig. 5 is shown. In Fig. In FIG. 5, dashed lines extending in the stacking direction indicate the overlap of the adhesive seal portions 26 and 27 in the stacking direction. Such a seal portion provided in the unit cell 100 and sealing the fluid flow path in the unit cell, as exemplified by the adhesive seal portions 26 and 27 in the present embodiment, is also referred to as a "first seal portion." The seal portion, including the first seal portion and the second seal portion, prevents fluid from flowing between the seal portion and the gas separator in contact with the seal portion at a portion where the seal portion is provided.

[0025] In Fig. 3, positions where the seals 60 and 62 and the adhesive seal portions 26 and 27 are provided when the fuel cell is viewed in the stacking direction are shown overlapping with the gas separator 50. The seals 60 and 62 are provided on the surface of the Fig. 3. The adhesive sealing sections 26 and 27 are provided on the back of the gas separator 50, which in Fig. 3 is not shown. Each of the seals 60 and 62 and the adhesive seal sections 26 and 27 extend linearly along the gas separator plane of the gas separator 50.

[0026] As in Fig. 3, the manifold holes 31, 33, 34, and 36 are each surrounded by the gasket 60 on the first surface of the gas separator 50. The adhesive seal portion 26 surrounds the outer side of the gasket 60 on the second surface of the gas separator 50. Therefore, in the fuel cell according to the present embodiment, the gasket 60 and the adhesive seal portion 26 provided along the outer periphery of the manifold holes 31, 33, 34, and 36 are arranged in this order from the side closer to the manifold holes 31, 33, 34, and 36 when the fuel cell is viewed in the stacking direction.

[0027] The seal 60 seals the gas distributor formed by the distributor holes 31, 33, 34, and 36 between cells. The adhesive seal portion 26 seals the gas distributor formed by the distributor holes 31, 33, 34, and 36 in the unit cell. As shown in Fig. As shown in Fig. 1, the resin frame 25 according to the present embodiment is provided with slit portions 39 at positions close to the manifold holes 31, 33, 34, and 36 and closer to the MEGA 18 than the manifold holes 31, 33, 34, and 36. Each of these slit portions 39 includes a plurality of slits corresponding to elongated through-holes extending from a position near the outer periphery of a corresponding one of the manifold holes 31, 33, 34, and 36 to a position close to the outer periphery of the MEGA 18. Each of the slits forms a communication flow path through which the corresponding one of the manifolds 31, 33, 34, and 36 communicates with the corresponding intra-cell gas flow path in the unit cell 100 when the resin frame 25 is sandwiched by the gas separators 40 and 50.Specifically, the manifold holes 33 and 34 communicate with the in-cell fuel gas flow path, and the manifold holes 31 and 36 communicate with the in-cell oxidizer gas flow path.

[0028] As in Fig. 3, the gasket 62 is arranged to completely surround an area provided with the electrodes (the anode 14 and the cathode 16) (also referred to as a power generation area 38) and areas provided with the distribution holes 31 to 36 when the fuel cell is viewed in the stacking direction. Fig. In Figure 3, the power generation region 38 is shown as a region surrounded by a dot-dash line. The power generation region 38 corresponds to a region where the intra-cell gas flow path is formed when the fuel cell is viewed in the stacking direction. The gasket 62 seals the inter-cell coolant flow path. The gaskets 60 and 62 are also referred to as a gas seal portion and a coolant seal portion, respectively.

[0029] As in Fig. 3, the above-described adhesive seal portion 27 provided in the resin frame 25 is arranged closer to the outer periphery of the gas separator 50 than the gasket 62 to surround the entire gasket 62 when the fuel cell is viewed in the stacking direction.

[0030] The adhesive seal portion 24 is formed on the resin frame 25 to surround the manifold holes 32 and 35 that form the coolant manifold. The adhesive seal portion 24 seals the coolant manifold in the unit cell 100.

[0031] As in Fig. 3, in the present embodiment, no further sealing element is provided, but a contact portion 88 is provided between the seal 60 and the distribution holes 31, 33, 34 and 36, at which the projections formed in the gas separators 40 and 50 come into contact with each other when the gas separator 50 is viewed in the stacking direction. As shown in Fig. 5, the contact portion 88 corresponds to a portion where a projection 43 formed in the gas separator 40 and a projection 53 formed in the gas separator 50 come into contact with each other. Likewise, as shown in Fig. 3, no further sealing element is provided, but a contact portion 86, at which the projections formed in the gas separators 40 and 50 come into contact with each other, is provided between the seal 62 and the outer peripheries of the power generation area 38 and the distribution holes 32 and 35. As shown in Fig. 2, the contact portion 86 corresponds to a portion where a projection 41 formed in the gas separator 40 and a projection 51 formed in the gas separator 50 come into contact with each other. In addition, as shown in Fig. 3, a contact portion 87 is provided along the outer periphery of the gas separator 50 at a position close to the outer periphery of the gas separator 50, at which projections formed in the gas separators 40 and 50 come into contact with each other. As shown in Fig. As shown in Fig. 5, the contact portion 87 corresponds to a portion where a protrusion 42 formed in the gas separator 40 and a protrusion 52 formed in the gas separator 50 come into contact with each other. These contact portions 86 to 88 are structures for ensuring the strength of the stack constituting the fuel cell. C. Method for manufacturing the fuel cell:

[0032] Fig. Fig. 6 is a diagram illustrating steps in a method for manufacturing a fuel cell according to the present embodiment. The steps for forming a sealing portion will be described below with reference to Fig. 6 described.

[0033] To manufacture a fuel cell, the MEA 10 is first prepared (step S100). Then, the cell frame assembly 20 is formed (step S110). The cell frame assembly 20 is formed by bonding the resin frame 25 to the outer peripheral portion of the MEA 10. In the present embodiment, before bonding the resin frame 25, the MEA 10 and the gas diffusion layers 15 and 17 are joined by pressing to form the MEGA 18. As shown in Fig. As shown in Fig. 2, the MEGA 18 according to the present embodiment has an exposed portion at the outer peripheral portion of the electrolyte membrane 12 that is not covered by the cathode 16 or the gas diffusion layer 17. A step portion having a step bottom surface 25b and a step side surface 25c is formed at an inner peripheral edge to form the opening 25a in the center of the resin frame 25. The MEGA 18 is inserted into this step portion, and the exposed portion of the outer peripheral portion of the electrolyte membrane 12 is bonded to the step bottom surface 25b. With the exposed portion of the outer peripheral portion of the electrolyte membrane 12 thus bonded to the step bottom surface 25b of the resin frame 25b, gas sealing is achieved between the in-cell fuel gas flow path and the in-cell oxidizing gas flow path.For example, the exposed portion of the electrolyte membrane 12 can be bonded to the stepped bottom surface 25b of the resin frame 25 as follows. Specifically, an adhesive layer containing an ultraviolet (UV) curable adhesive can be provided on the resin frame 25 and irradiated with UV light. Examples of the UV-curable adhesive that can be used include adhesives including polyisobutylene and butyl rubber.

[0034] The gas separators 40 and 50 are prepared (step S120). The seals 60 and 62 are arranged on one surface (first surface) of the gas separator 50 (step S130). The seals 60 and 62 can be attached or glued to the gas separator 50, for example, with adhesive.

[0035] The cell frame assembly 20 and the pair of gas separators 40 and 50 sandwiching the cell frame assembly 20 are placed between molds for hot pressing (step S140). Subsequently, the resin frame 25 and the gas separators 40 and 50 are bonded to each other by hot pressing (step S150), thereby forming the unit cell 100. Specifically, in step S140, the pair of gas separators 40 and 50 sandwich the cell frame assembly 20, and the other surface (second surface) of the gas separator 50 is brought into contact with the cell frame assembly 20 without the gaskets 60 and 62.

[0036] Fig. Fig. 7 is a cross-sectional view schematically illustrating how hot pressing is performed using the molds in step S150. The position of the cross-sectional view in Fig. 7 is the same as this one in Fig. 4 and Fig. 5. The molds used in the present embodiment include a first mold 70 and a second mold 71. The first mold 70 used in step S150 includes a pair of head portions 72 and 73. The head portion 72 is provided to come into contact with the gas separator 50 at a position where the Fig. 3 is formed. The head portion 73 is provided to come into contact with the gas separator 50 at a position where the Fig. 3 is formed. Thus, the head portion 72 and the head portion 73 are provided at positions on both sides of the seal 62 in a direction perpendicular to the stacking direction. Although in Fig. 7, the first mold 70 further comprises a head portion for forming the adhesive seal portion 24 described above. These head portions may correspond to separately formed elements or to an integrally formed single element.

[0037] As in Fig. As shown in Fig. 7, the second mold 71 according to the present embodiment has a continuous portion in contact with the gas separator 40 to overlap with the head portions 72 and 73 as viewed in the stacking direction. This portion of the second mold 71 to contact the gas separator 40 is formed as a flat surface without any unevenness. Note that the second mold 71 may have any other shape as long as hot pressing can be performed with the head portions of the first mold 70.

[0038] In step S150, after the elements are arranged between the first mold 70 and the second mold 71, the resin frame 25 and the gas separators 40 and 50 are hot-pressed with a load and heat applied between the first mold 70 and the second mold 71. Thus, the adhesive seal portions 24, 26, and 27 are formed at positions of the resin frame 25 as shown in Fig. 3 shown.

[0039] After step S150, a plurality of unit cells 100 each having the formed adhesive seal portions 24, 26, and 27 are stacked (step S160), and the resulting stack is completely fixed in the stacking direction, thereby completing the fuel cell.

[0040] In the fuel cell according to the present embodiment having the above-described configuration, the gasket 60 and the adhesive seal portion 26, which are provided along the outer periphery of the manifolds 31, 33, 34, and 36, are arranged in this order from the side closer to the manifolds 31, 33, 34, and 36 when the fuel cell is viewed in the stacking direction. Thus, since the gasket is arranged closer to the manifold than the adhesive seal portion, the adhesive seal portion is less likely to be peeled off. The gasket formed of an elastic member achieves sealing by generating a reaction force upon receiving a compressive force in the stacking direction between the two gas separators 40 and 50.As a result, compared to the adhesive seal portion, the seal is less likely to peel off when the release force is applied between the gas separators by a high-pressure fluid in the manifold. Thus, the above-described arrangement can improve the durability of the seal in the fuel cell under the release force applied between the gas separators 40 and 50 from the manifold side due to the gas pressure in the manifold.

[0041] In the fuel cell according to the present embodiment described above, the sealing portions that seal the intra-cell and inter-cell fluid flow paths each comprise the adhesive sealing portion 24, 26, and 27 or the gaskets 60 and 62. Therefore, the sealing portions can be formed by simple methods such as hot pressing and bonding, eliminating the need for a tedious heating process for curing the entire members constituting the sealing portions. Thus, the fuel cell can be manufactured using efficient processes. Overall, the above-described durability of the seal in the fuel cell and productivity can be improved.

[0042] In the present embodiment, the gasket 62 and the adhesive seal portion 27 provided along the outer periphery of the power generation region 38 are arranged in this order from the side closer to the power generation region 38 in the section of the cross-sectional view along the Fig. 3, that is, in the outer peripheral region along the side extending in the X direction in the rectangular gas separator 50. This region near the outer periphery of the power generation region 38 corresponds to a region that receives the separating force between the gas separators 40 and 50 from the power generation region 38 side due to the gas pressure in the intra-cell gas flow path formed in the power generation region 38. In such a region, the gasket 62 and the adhesive seal portion 27 are arranged in this order from the side closer to the power generation region 38, so that a similar effect to the gasket 60 and the adhesive seal portion 26 provided outside the outer periphery of the above-described manifold can be achieved.In particular, the gasket 62 can prevent the peeling of the adhesive seal portion 27 due to pressure in the intra-cell gas flow path formed in the power generation region 38. Therefore, peeling is less likely to occur between the gas separators 40 and 50.

[0043] The release force between the adjacent gas separators 40 and 50 can be generated by a factor other than the pressure of the fluid flowing in the manifold and the pressure of the gas flowing in the gas flow path formed in the power generation region 38, as described below. As described above, the contact portion 88 is provided between the manifold and the gasket 60 when the fuel cell is viewed in the stacking direction (see Fig. 3 and Fig. 5). The contact portion 88 corresponds to a portion where the projection 43 formed on the gas separator 40 and the projection 53 formed on the gas separator 50 come into contact with each other. This contact portion 88 receives a compressive force in the stacking direction during the mounting of the fuel cell. Fig. In Fig. 4, a white arrow indicates the force α in the stacking direction applied to the protrusion 53 of the gas separator 50 at the contact area 88. When this force is applied, a force β is generated in a direction to detach the gas separator 50 from the resin frame 25, with a portion F serving as a fulcrum. The portion F corresponds to a portion where the protrusion 53 is raised from the portion of the gas separator 50 in contact with the resin frame 25. In Fig. In Figure 4, the section F is indicated by an arrow, and a white arrow represents the force β generated in the gas separator 50. In the present embodiment, the contact section 88, which leads to the force β, is provided outside the manifold. However, the gasket 60 and the adhesive seal section 26 are arranged in this order so that they are closer to the outer periphery than the contact section 88. This can prevent the gas separator from detaching from the resin frame 25.

[0044] As in Fig.As shown in Fig. 3, in the present embodiment, the gasket 62, which corresponds to one of the gaskets 60 and 62 provided inside the cell and serves as the coolant sealing portion, is formed so as to surround the outside of the gasket 60 serving as the gas sealing portion when the fuel cell is viewed in the stacking direction. With the coolant sealing portion thus provided to surround the gas sealing portion, even if leakage occurs from the gas sealing portion, the coolant flow path in which the coolant flows and the coolant sealing portion can prevent the gas from leaking out of the fuel cell. In particular, this configuration can be applied to the gas sealing portion that seals fuel gas including hydrogen, so that safety can be improved when preventing hydrogen from leaking out.The coolant sealing portion may be formed to have a continuous linear shape surrounding the gas sealing portion, which is similar to the shape of the gasket 62 according to the present embodiment in terms of preventing gas leakage. Note that the configuration of surrounding the outside of the gas sealing portion with the coolant sealing portion may not necessarily be used if the gas sealing portion can seal the gas with sufficient reliability. D. Alternative Embodiments:(D-1) Alternative Embodiment 1:

[0045] For the configuration of the above-described embodiment, an alternative configuration may be employed in which the entire circumference of each of the manifold holes 31, 33, 34, and 36 is surrounded by the gasket 60 and the adhesive seal portion 26. For example, the gasket 60 may have a discontinuous portion instead of surrounding the entire circumference of the manifold holes 31, 33, 34, and 36. Even with this configuration, the gas separators 40 and 50 can be prevented from detaching from the manifold side, and the above-described effects can be achieved, with the gasket 60 and the adhesive seal portion 26 being arranged in this order from the side closer to the manifold hole.Note that the configuration of surrounding the entire circumference of the manifold holes 31, 33, 34, and 36 with the gasket 60 can reduce the pressure applied to the adhesive seal portion 26 and the release force on the adhesive seal portion 26. Each of the adhesive seal portions 26 may not have an independent annular shape and may have any shape as long as the sealing of the cell interior is ensured in the fuel cell as a whole. (D-2) Alternative embodiment 2:

[0046] For the configuration of the above-described embodiment, an alternative configuration may be employed in which the gasket 62 and the adhesive seal portion 27 provided along the outer periphery of the power generation region 38 are arranged in this order from the side closer to the power generation region 38 when the fuel cell is viewed in the stacking direction. The detachment of the gas separators 40 and 50 from the outer periphery of the manifold hole can be prevented as long as the configuration of arranging the gasket and the adhesive seal portion is adopted in this order from the side closer to the manifold when the fuel cell is viewed in the stacking direction. (D-3) Alternative embodiment 3:

[0047] An alternative configuration may be employed for the gas manifold configuration of the above-described embodiment. Specifically, the gasket and the adhesive seal portion are arranged closer to the manifold in this order from the side when the fuel cell is viewed in the stacking direction. This configuration may be employed, for example, for the coolant manifold instead of the gas manifold, or for both the coolant manifold and the gas manifold. In such a case, for example, the gasket surrounding the coolant manifold may be discontinuous, or another similar configuration may be employed to cause the coolant manifold and the inter-cell coolant flow path to communicate with each other. (D-4) Alternative embodiment 4:

[0048] In the above-described embodiment, the adhesive portions 24, 26, and 27 are formed by hot-pressing the resin frame 25 bonded to the outer peripheral portion of the MEA 10 (MEGA 18). Alternatively, the adhesive seal portion 26 may be formed using a seal member having a different shape than that of the resin frame 25. For example, at least some of the adhesive seal portions 24, 26, and 27 may be formed by a seal member different from the seal members for forming the other adhesive seal portion. (D-5) Alternative embodiment 5:

[0049] An alternative configuration may be employed for the configuration of the above-described embodiment, in which the adhesive seal portion is disposed inside the unit cell 100 and the gasket is provided between unit cells 100. Specifically, the gasket may be used to seal the inside of the unit cell 100, and the adhesive seal portion may be used to seal between the unit cells 100. Also in this configuration, a similar effect to that of the above-described embodiment can be achieved by arranging the gasket and the adhesive seal portion, which are provided along the outer periphery of the manifold, in this order from the side closer to the manifold when the fuel cell is viewed in the stacking direction.

[0050] The present disclosure is not limited to the embodiments described above and may be implemented with various configurations without departing from the scope of the present disclosure as defined by the claims.

Claims

[1] A fuel cell comprising a plurality of stacked unit cells (100), each of the unit cells (100) comprising: a membrane electrode assembly (10) having an electrolyte membrane (12) on both surfaces of which electrodes (14, 16) are formed; a pair of gas separators (40, 50) comprising a gas separator (50) provided on the side of a first surface of the membrane electrode assembly (10) and a gas separator (40) provided on the side of a second surface of the membrane electrode assembly (10); and a first sealing portion (24, 26, 27) provided outside an outer periphery of the membrane electrode assembly (10) between the pair of gas separators (40, 50), wherein the fuel cell further comprises: a second sealing portion (60, 62) provided between adjacent ones of the unit cells (100); a first distributor (31, 33, 34, 36) in which reaction gas flows, the first distributor (31, 33, 34, 36) being formed through the fuel cell in a stacking direction of the unit cells (100) and communicating with an intra-cell gas flow path through which the reaction gas flows between the membrane electrode assembly (10) and the gas separator (40, 50); and a second distributor (32, 35) in which a coolant flows, the second distributor (32, 35) being formed through the fuel cell in the stacking direction of the unit cells (100) and communicating with an inter-cell coolant flow path in which the coolant flows between adjacent ones of the unit cells (100), wherein one portion of the first sealing portion (24, 26, 27) and the second sealing portion (60, 62) comprises adhesive sealing portions that adhere to the two gas separators (40, 50) in contact with the one portion of the first sealing portion (24, 26, 27) and the second sealing portion (60, 62), and the other portion of the first sealing portion (24, 26, 27) and the second sealing portion (60, 62) comprises seals, and wherein one of the seals (60) and one of the adhesive seal portions (26) are arranged in this order from a side closer to the first manifold (31, 33, 34, 36) and / or the second manifold (32, 35) when the fuel cell is viewed in the stacking direction, wherein the one of the seals (60) and the one of the adhesive seal portions (26) are provided along an outer periphery of the first manifold (31, 33, 34, 36) and / or the second manifold (32, 35). [2] Fuel cell according to claim 1, wherein the second sealing portion (60, 62) comprises a coolant sealing portion (62) configured to seal the inter-cell coolant flow path and a gas sealing portion (60) configured to seal the first manifold (31, 33, 34, 36), and the coolant sealing portion (62) is formed to surround an outer side of the gas sealing portion (60) when the fuel cell is viewed in the stacking direction. [3] Fuel cell according to claim 1 or 2, wherein the unit cells (100) each further comprise a resin frame (25) connected to an outer periphery of the membrane electrode assembly (10) between the pair of gas separators (40, 50), the first distributor (31, 33, 34, 36) and the second distributor (32, 35) are formed by sections in which the resin frame (25) and the gas separator (40, 50) are stacked, the first sealing section (24, 26, 27) corresponds to the adhesive sealing section, and the adhesive sealing portion corresponds to a part of the resin frame (25). [4] The fuel cell according to any one of claims 1 to 3, wherein another of the gaskets (62) and another of the adhesive seal portions (27) are arranged in this order from the side closer to the electrode (14, 16) when the fuel cell is viewed in the stacking direction, the other of the gaskets (62) and the other of the seal portions (27) being provided at positions along the outer circumference of the electrode (14, 16). [5] A method of manufacturing a fuel cell having a plurality of stacked unit cells (100), the method comprising: Preparing a membrane electrode assembly (10) having an electrolyte membrane (12) on both surfaces of which electrodes (14, 16) are formed; Preparing a pair of gas separators (40, 50) in which manifold holes are formed, the manifold holes being configured to form manifolds in which a means of reaction gas and coolant flows, the manifolds each being formed through the fuel cell in a stacking direction of the unit cells (100) and communicating with an intra-cell gas flow path through which the reaction gas flows on the membrane electrode assembly (10) or communicating with an inter-cell coolant flow path in which the coolant flows between adjacent ones of the unit cells (100); Disposing one of the pair of gas separators (40, 50) on the side of one surface of the membrane electrode assembly (10) and disposing the other of the pair of gas separators (40, 50) on the side of the other surface of the membrane electrode assembly (10); Providing a first sealing portion (24, 26, 27) outside an outer periphery of the membrane electrode assembly (10) between the pair of gas separators (40, 50); and Providing a second sealing portion (60, 62) on a surface of one of the pair of gas separators (40, 50) opposite to a side on which the membrane electrode assembly (10) is provided, wherein wherein the provision of the first sealing portion (24, 26, 27) and the provision of the second sealing portion (60, 62) comprise: Bonding a sealing member (25) configured to form a sealing portion from the first sealing portion (24, 26, 27) and the second sealing portion (60, 62), and the two gas separators (40, 50) in contact with the sealing member (25) to each other by hot pressing to form adhesive sealing portions as one of the first sealing portions (24, 26, 27) and the second sealing portion (60, 62), and arranging the other of the first sealing portions (24, 26, 27) and the second sealing portion (60, 62) as seals; and Arranging one of the gaskets (60) and one of the adhesive seal portions (26) in this order from a side closer to the manifold when the fuel cell is viewed in the stacking direction, wherein the one of the gaskets (60) and the one of the adhesive seal portions (26) are provided along an outer periphery of the manifold. [6] A method of manufacturing a fuel cell according to claim 5, further comprising: Connecting a resin frame (25) serving as the sealing member to an outer peripheral portion of the membrane electrode assembly (10) to form a cell frame assembly (20), wherein providing the first sealing portion (24, 26, 27) comprises sandwiching the cell frame assembly (20) between the pair of gas separators (40, 50) and then hot-pressing the resin frame (25) and the pair of gas separators (40, 50) to form the adhesive sealing portion.

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