Power generation unit cell, and fuel cell

Abstract

To provide an electric power generation unit cell comprising a structure capable of achieving both of sealability and dimension stability.SOLUTION: An electric power generation unit cell includes: a polymer electrolyte; a film electrode assembly having a catalyst layer arranged so as to nip the polymer electrolyte; a support medium that is arranged so as to surround the film electrode assembly; and a pair of separators arranged so as to nip the film electrode assembly and the support medium. The support medium includes a base material and an adhesion layer laminated onto both surfaces of the base material. The separator includes: a seal part which is a smooth surface at a portion adhered to the adhesive layer of the support medium; and a restraint part having unevenness.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present disclosure relates to a fuel cell.

Background Art

[0002] Patent Document 1 discloses providing protrusions on ribs on the adhesive side in order to ensure the thickness of the adhesive layer. Thereby, the required adhesive layer thickness can be ensured. Further, in Patent Document 2, a clamping load is applied to the laminate 14 of the fuel cell stack 10 in the stacking direction of the power generation cells 12. A first corrugated convex portion 70 is integrally provided on the outer side of the sealing bead portion 51 of the first metal separator 30, and a second corrugated convex portion 80 is integrally provided on the outer side of the sealing bead portion 61 of the second metal separator 32. It is disclosed that the first corrugated convex portion 70 and the second corrugated convex portion 80 overlap in a state where the waveforms are shifted from each other when viewed in the stacking direction.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The resin frame (support) is provided on the outer periphery of the power generation unit cell and has a function of sealing the inside of the power generation unit cell. However, there are problems such as a decrease in sealing performance, adhesive strength, and dimensional stability due to dimensional changes caused by heat and movement due to external forces such as pressure or impact. In the invention described in Patent Document 1, although the bonding thickness can be ensured, when the number of ribs is increased, voids such as bubbles are likely to occur, which may become the starting point of leakage and reduce the sealing performance. In addition, since ribs are provided at the parts that require airtightness by sealing, it is impossible to ensure both sealing performance (leakage) and dimensional stability at the same time. The invention described in Patent Document 2 is a means for reducing the input by moment to the welding part in the metal spring seal, but it cannot suppress dimensional changes due to thermal shrinkage, creep, etc. of the frame (support). That is, since it is a wavy bead installed to reduce the bending moment, the effect of suppressing the movement of the frame (support) cannot be expected.

[0005] In view of the above problems, an object of the present disclosure is to provide a power generation unit cell having a structure capable of achieving both sealing performance and dimensional stability. In addition, a fuel cell using this power generation unit cell is provided.

Means for Solving the Problems

[0006] The present application is a power generation unit cell having an electrolyte membrane, a membrane electrode assembly having catalyst layers arranged so as to sandwich the electrolyte membrane, a support arranged so as to surround the membrane electrode assembly, and a pair of separators arranged so as to sandwich the membrane electrode assembly and the support. The support has a base material and adhesive layers laminated on both surfaces of the base material, and the separator has a seal portion that is a smooth surface and a restraint portion having irregularities at a portion that adheres to the adhesive layer of the support. A power generation unit cell is disclosed. In addition, a fuel cell formed by laminating a plurality of such power generation unit cells is disclosed.

Effects of the Invention

[0007] According to the present disclosure, since a portion with high sealing performance and a portion for improving dimensional stability are provided separately, both functions can be achieved with high performance.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0009] 1. Power generation unit cell FIGS. 1 to 3 show diagrams for explaining the power generation unit cell 10 according to one form. The power generation unit cell 10 is a unit element for generating power by supplying hydrogen and oxygen (air), and a plurality of such power generation unit cells 10 are stacked to form a fuel cell. FIG. 1 is a plan view of the power generation unit cell 10, FIG. 2 is a diagram for explaining the layer structure in the power generation section 11 of the power generation unit cell 10, and FIG. 3 is a diagram for explaining the layer structure in the outer peripheral portion 21 of the power generation unit cell 10.

[0010] 1.1. Power generation section The power generation section 11 is a portion that contributes to power generation, for example, in the portion surrounded by a dotted line in FIG. 1, and as shown in FIG. 2 representing the layer structure (a part of the A - A cross-section) in the power generation section 11, a plurality of layers are stacked. In the power generation unit 10 of the power generation unit cell, one side is the cathode (oxygen supply side) and the other side is the anode (hydrogen supply side) with the electrolyte membrane 12 interposed therebetween. On the cathode side, a cathode catalyst layer 13, a cathode gas diffusion layer 14, and a cathode separator 15 are laminated in this order from the electrolyte membrane 12 side. On the other hand, the anode includes an anode catalyst layer 16, an anode gas diffusion layer 17, and an anode separator 18 in this order from the electrolyte membrane 12 side. Note that the laminate of the electrolyte membrane 12, the cathode catalyst layer 13, and the anode catalyst layer 16 (a laminate with the electrolyte membrane sandwiched between the catalyst layers) may be referred to as a membrane electrode assembly. The thickness of the membrane electrode assembly is typically about 0.4 mm, and the thickness of the power generation unit cell 10 in the power generation unit 11 is typically about 1.3 mm. Each layer is as follows, for example.

[0011] 1.1.1. Electrolyte Membrane The electrolyte membrane 12 is a solid polymer electrolyte membrane that exhibits good proton conductivity in a wet state. For example, it is composed of a fluorine-based ion exchange membrane. For example, a carbon-fluorine-based polymer can be used, and specifically, perfluoroalkylsulfonic acid-based polymers (Nafion (registered trademark)) and the like can be mentioned. The thickness of the electrolyte membrane 12 is not particularly limited, but is preferably 200 μm or less, more preferably 100 μm or less, and even more preferably 50 μm or less.

[0012] 1.1.2. Cathode Catalyst Layer The cathode catalyst layer 13 is a layer containing a catalyst metal in a form in which the catalyst metal is supported on a carrier. For example, examples of the catalyst metal include Pt, Pd, Rh, or an alloy containing these. Examples of the carrier include a carbon carrier, and more specifically, carbon particles composed of glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite.

[0013] 1.1.3. Anode Catalyst Layer The anode catalyst layer 16 is also a layer containing a catalyst metal in a form in which the catalyst metal is supported on a carrier, similar to the cathode catalyst layer 13. For example, examples of the catalyst metal include Pt, Pd, Rh, or an alloy containing these. Examples of the carrier include carbon carriers, more specifically, carbon particles composed of glassy carbon, carbon black, activated carbon, coke, natural graphite, and artificial graphite, etc.

[0014] 1.1.4. Cathode Gas Diffusion Layer In this embodiment, the cathode gas diffusion layer 14 is, for example, a layer composed of a porous body having conductivity. More specific examples include carbon porous bodies (carbon paper, carbon cloth, glassy carbon, etc.), metal porous bodies (metal mesh, foamed metal), etc. An MPL (micro-porous layer) may be provided on the cathode gas diffusion layer 14 as needed. The MPL is a coating-like thin film coated on the side of the cathode catalyst layer 13 in the cathode gas diffusion layer 14. The MPL has a function of adjusting moisture by having water repellency or hydrophilicity as needed. It also serves to prevent fluff or the like generated in the carbon porous body from piercing the electrolyte membrane. Typically, the MPL is mainly composed of a water-repellent resin such as polytetrafluoroethylene (PTFE) and a conductive material such as carbon black.

[0015] The thickness of the cathode gas diffusion layer 14 in the power generation unit 11 is preferably 50 μm or more and 250 μm or less. If this thickness exceeds 250 μm, the electron resistance increases, and if it is thinner than 50 μm, the flexibility of the cathode gas diffusion layer is insufficient, and a uniform surface pressure may not be obtained in the power generation unit 11. More specifically, a surface pressure of 0.2 MPa or more and 2 MPa or less is applied to the power generation unit 11, and the springiness (elasticity) of the cathode gas diffusion layer 14 is utilized to make the surface pressure in the power generation unit 11 constant.

[0016] 1.1.5. Anode Gas Diffusion Layer The anode gas diffusion layer 17 is a layer composed of, for example, a porous body having conductivity. More specific examples include carbon porous bodies (carbon paper, carbon cloth, vitreous carbon, etc.), metal porous bodies (metal mesh, foamed metal), and the like.

[0017] The thickness of the anode gas diffusion layer 17 in the power generation unit 11 is preferably 50 μm or more and 250 μm or less. If this thickness exceeds 250 μm, the electron resistance increases. If it is thinner than 50 μm, the flexibility of the anode gas diffusion layer is insufficient, and a uniform surface pressure may not be obtained in the power generation unit 11. More specifically, a surface pressure of 0.2 MPa or more and 2 MPa or less is applied to the power generation unit 11, and the springiness (elasticity) of the anode gas diffusion layer 14 is utilized to make the surface pressure in the power generation unit 11 constant.

[0018] 1.1.6. Cathode Separator The cathode separator 15 is a member that supplies a reaction gas (air in this form) to the cathode gas diffusion layer 14. It has a plurality of grooves 15a on the surface facing the cathode gas diffusion layer 14, and these grooves function as reaction gas flow paths. The shape of the grooves is not particularly limited as long as the reaction gas can be appropriately supplied to the cathode gas diffusion layer 14. Examples include those in which a plate-like member is formed into a wave shape to form grooves as in this form. At that time, the plate thickness is typically 0.1 mm or more and 0.2 mm or less, and the height of the unevenness is typically about 0.5 mm. In this case, grooves 15b are formed on the opposite side across the cathode separator 15 between adjacent grooves 15a, and these function as cooling water flow paths.

[0019] Further, as can be seen from FIG. 1, in the cathode separator 15, at a position extending from the power generation unit 11 to the outside and at one end side in the direction in which the grooves 15a and 15b extend, an air inlet hole A in , a cooling water inlet hole W in , and a hydrogen outlet hole H out are provided. At the other end side in the direction in which the grooves 15a and 15b extend, an air outlet hole A out , a cooling water outlet hole W out , and a hydrogen inlet hole H inis provided. Here, the groove 15a communicates with the air inlet hole A in , the air outlet hole A out , and the groove 15b communicates with the cooling water inlet hole W in , the cooling water outlet hole W out .

[0020] The material constituting the cathode separator 15 may be any material that can be used as a separator for the power generation unit cell, and may be a gas-impermeable conductive material. Examples of such materials include dense carbon obtained by compressing carbon to make it gas-impermeable, and press-molded metal plates, etc.

[0021] 1.1.7. Anode separator The anode separator 18 is a member that supplies the reaction gas (hydrogen) to the anode gas diffusion layer 17, and has a plurality of grooves 18a on the surface facing the anode gas diffusion layer 17, and these grooves function as reaction gas flow paths. The shape of the grooves is not particularly limited as long as the reaction gas can be appropriately supplied to the anode gas diffusion layer 17, and examples include those in which a plate-like member is formed into a wave shape to form grooves as in this embodiment. At that time, the plate thickness is typically 0.1 mm or more and 0.2 mm or less, and the height of the unevenness is typically about 0.4 mm. In this case, grooves 18b are formed on the opposite side across the anode separator 18 between adjacent grooves 18a, and this functions as a cooling water flow path.

[0022] Also, as can be seen from FIG. 1, in the anode separator 18, at a position extending from the power generation unit 11 to the outside, at a part on one end side in the direction in which the grooves 18a and 18b extend, there are provided an air inlet hole A in , a cooling water inlet hole W in , a hydrogen outlet hole H out , and at a part on the other end side in the direction in which the grooves 18a and 18b extend, there are provided an air outlet hole A out , a cooling water outlet hole W out , a hydrogen inlet hole H in . Here, the groove 18a communicates with the hydrogen inlet hole H in , the hydrogen outlet hole H out , and the groove 18b communicates with the cooling water inlet hole W in, the cooling water outlet hole W out is in communication with.

[0023] The material constituting the anode separator 18 may be any material that can be used as a separator for the power generation unit cell, and may be a gas-impermeable conductive material. Examples of such materials include dense carbon obtained by compressing carbon to make it gas-impermeable, and press-molded metal plates.

[0024] 1.1.8. Power generation by the power generation section As is well known, power generation is performed as follows by the power generation unit cell 10 described above. The hydrogen inlet hole H in The hydrogen supplied from the groove 18a of the anode separator 18 passes through the anode gas diffusion layer 17 and is decomposed into protons (H + ) and electrons (e - ) in the anode catalyst layer 16. The protons pass through the electrolyte membrane 12, and the electrons pass through the conductive wire connected to the outside, and each reaches the cathode catalyst layer 13. The remaining hydrogen is discharged from the hydrogen outlet hole H out . Oxygen (air) is supplied to the cathode catalyst layer 13 from the air inlet hole A in through the groove 15a of the cathode separator 15 and the cathode gas diffusion layer 14. In the cathode catalyst layer 13, water (H2O) is generated by protons, electrons, and oxygen. The generated water and the remaining air pass through the cathode gas diffusion layer 14 and reach the groove 15a of the cathode separator 15 and are discharged from the air outlet hole A out . In the power generation unit cell 10, the flow of electrons passing through the conductive wire connected to the outside from the anode catalyst layer 16 is utilized as an electric current.

[0025] In addition, when a plurality of power generation unit cells 10 are stacked to form a fuel cell, in adjacent power generation unit cells 10, the anode separator 18 of one power generation unit cell 10 adjacent to the cathode separator 15 of the other power generation unit cell 10 is arranged so as to overlap, whereby a cooling water flow path is formed by the groove 15b of the cathode separator 15 and the groove 18b of the anode separator 18. Cooling water inlet hole W in supplies cooling water from, and the supplied cooling water cools the power generation unit cell 10 and is discharged from the cooling water outlet hole W out .

[0026] 1.2. Outer Periphery The outer periphery 21 is the outer periphery of the power generation unit cell 10 outside the power generation part 11 surrounded by a dotted line in FIG. 1, and as shown in FIG. 3 representing the layer structure (a part of the B - B cross section) of the outer periphery 21, a plurality of layers are laminated. FIG. 4 shows an enlarged view of a part of FIG. 3.

[0027] 1.2.1. Basic Structure of Outer Periphery As can be seen from FIGS. 3 and 4, in this embodiment, the outer periphery 21 has at least a part of the following structure. The end faces of the electrolyte membrane 12, the anode catalyst layer 16, and the anode gas diffusion layer 17 are laminated so as to be generally at the same position, and the end face of the cathode catalyst layer 13 is laminated so as to be recessed (receded) from the end face of the electrolyte membrane 12. Further, the end face of the cathode gas diffusion layer 14 protrudes (advances) from the end face of the electrolyte membrane 12 and extends to a position overlapping the support 23 in a plan view of the power generation unit cell 10 (the viewpoint from the direction of FIG. 1, the line of sight in the direction indicated by the arrow Z in FIG. 3). The support 23 will be described later.

[0028] The cathode separator 15 and the anode separator 18 are arranged at the outer peripheral portion 21 so as to sandwich each of the above-described layers in the same manner as the power generation unit 11 therebetween. At the outer peripheral portion 21, the outer peripheries of the cathode separator 15 and the anode separator 18 extend so as to protrude from the end faces of the membrane electrode assembly, the cathode gas diffusion layer 14, and the anode gas diffusion layer 17, and a support 23 is disposed between the cathode separator 15 and the anode separator 18 at the extended portion. Note that at the outer peripheral portion 21, since no flow paths are required for either the cathode separator 15 or the anode separator 18, the grooves 15a and 18a are not formed (however, as can be seen from FIG. 3, this does not prevent the formation of grooves in part). That is, in the power generation unit cell 10, the laminate including the membrane electrode assembly in the power generation unit 11 and the support 23 at the outer peripheral portion 21 are configured to be sandwiched between a pair of separators (the cathode separator 15 and the anode separator 18).

[0029] Further, a cover sheet 22 is disposed so as to bridge the end of the surface of the support 23 facing the cathode side and the end of the surface of the membrane electrode assembly facing the cathode side. The cover sheet 22 will be described later.

[0030] 1.2.2. Support The above-described support 23 functions as a member that seals between the cathode separator 15 and the anode separator 18 at the outer peripheral portion 21 of the power generation unit cell 10. FIG. 5 shows a view of the support 23 in plan view (from the same viewpoint as FIG. 1). As can be seen from FIG. 5, the support 23 is a frame-shaped member, and has an air inlet hole A in , a cooling water inlet hole W in , a hydrogen outlet hole H out , an air outlet hole A out , a cooling water outlet hole W out , a hydrogen inlet hole H in , and a hole is provided such that a portion 23d corresponding to the power generation unit 11 is hollow.

[0031] The support 23 includes a base material 23a and adhesive layers 23b on both surfaces of the base material 23a (the surface facing the cathode side and the surface facing the anode side). By adhering the adhesive layers 23b to the cathode separator 15 and the anode separator 18, the power generation unit 11 is sealed between the pair of separators. Therefore, the distance between the cathode separator 15 and the anode separator 18 is bent so as to change depending on the layer sandwiched therebetween. As can be seen from FIGS. 3 and 4, in the portion where only the support 23 is arranged, the distance is narrowed in part, and the support 23 is sandwiched and fixed by the cathode separator 15 and the anode separator 18 (the pair of separators), and this serves as the sealing portion 24. The sealing portion 24 will be described later.

[0032] The base material 23a is formed from any material having electrical insulation and airtightness. Examples of such materials include crystalline polymers, more specifically, engineering plastics. Examples of engineering plastics include polyethylene naphthalate-based resins (PEN) and polyethylene terephthalate-based resins (PET), polyphenylene ether (PPE), polyphenyl sulfone (PPSU), polysulfone (PSU), polyether sulfone (PSU), polyether ether ketone (PEEK), polyimide (PI), polyether imide (PEI), polyamide imide (PAI), polyphenyl sulfide (PPS), syndiotactic polystyrene (SPS), nylon-based resins, and the like. The thickness of the base material 23a is not particularly limited, but is preferably 0.05 mm or more and 0.25 mm or less.

[0033] The adhesive layer 23b may be any known material as long as it has adhesiveness in the adhered state. Examples of the adhesive used for the adhesive layer include polyolefin-based polymers containing maleic acid and maleic anhydride. More specifically, for example, Admer (registered trademark, Mitsui Chemicals, Inc.) can be mentioned. The thickness of the adhesive layer 23b is not particularly limited, but is preferably 30 μm or more and 50 μm or less.

[0034] Such a support 23 is arranged to surround the laminate of the power generation unit 11 including the membrane electrode assembly inside its frame shape. At this time, as can be seen from FIG. 3, its end face is positioned so as to face the end faces of the membrane electrode assembly and the anode gas diffusion layer 17 with a space A therebetween. This space A can absorb dimensional changes due to linear expansion of the support 23, the membrane electrode assembly, etc., and can suppress the occurrence of damage due to expansion and contraction. More specifically, it is preferable that the distance in the direction in which the support 23, the membrane electrode assembly, and the anode gas diffusion layer 17 face each other in this space A is 0.01 mm or more and 2 mm or less. If the distance is less than 0.01 mm, it becomes difficult to absorb dimensional changes of the support 23, and if the distance exceeds 2 mm, deformation or damage may occur in the support 23 due to the differential pressure between the space A and the cathode gas diffusion layer 14, resulting in a decrease in sealing performance.

[0035] 1.2.3. Cover sheet As described above, the cover sheet 22 is arranged so as to span the end of the surface of the support 23 facing the cathode side and the end of the surface of the membrane electrode assembly facing the cathode side.

[0036] One end of the cover sheet 22 is arranged to cover the surface end of the cathode side of the support 23, and the other end is arranged to cover at least one of the surface ends of the electrolyte membrane 12 and the cathode catalyst layer 13 on the membrane electrode assembly side (in this embodiment, the cover sheet is arranged to cover both surface ends of the electrolyte membrane 12 and the cathode catalyst layer 13). Thereby, the cathode and the anode can be appropriately separated at the outer peripheral portion 21. Therefore, the cover sheet 22 is arranged between the membrane electrode assembly and the cathode gas diffusion layer 14 at the end on the membrane electrode assembly side.

[0037] The cover sheet 22 is made of a material that does not allow the reaction gas of the fuel cell to permeate. As a member that does not allow the reaction gas to permeate, for example, a film-like member made of a resin such as polypropylene, polyphenylene sulfide, polyethylene naphthalate, nylon, ethylene vinyl alcohol copolymer, etc. can be adopted. Particularly from the viewpoints of hydrolysis resistance and adhesion to the electrolyte membrane, nylon 11, nylon 12, nylon 9T, and ethylene vinyl alcohol can be mentioned. Further, an additive having an amide group, an epoxy group, a hydroxyl group, etc. may be added in order to increase the adhesiveness to the electrolyte membrane 12.

[0038] The cover sheet 22 is adhered from the adhesive layer 23b of the support 23 at the portion overlapping the support 23. On the other hand, for the portion where the cover sheet 22 overlaps the membrane electrode assembly, an adhesive layer is provided on the cover sheet 22 and adhered as necessary. However, when nylon is used as the cover sheet 22, since the cover sheet and the membrane electrode assembly can be adhered by thermocompression bonding, it is also possible not to require an adhesive layer.

[0039] 1.2.4. Sealing portion In the sealing portion 24, only the support 23 is disposed between the cathode separator 15 and the anode separator 18, and the support 23 is sandwiched and fixed by the cathode separator 15 and the anode separator 18 for sealing. The sealing portion 24 is configured to be able to seal depending on the forms of the cathode separator 15, the anode separator 18, and the support 23. Specifically, it is as follows.

[0040] As can be seen from FIGS. 3 and 4, in this embodiment, the sealing portion 24 includes a seal portion 25 and a restraint portion 26. In this embodiment, protrusions 24a are disposed on the cathode separator 15 and the anode separator 18 between the seal portion 25 and the restraint portion 26.

[0041] [Seal portion] The seal portion 25 is a portion where the surface 25a that contacts the adhesive layer 23b of the support 23 is smoothed out among the cathode separator 15 and the anode separator 18, and high sealing performance is exhibited by the contact between the smooth surface 25a and the adhesive layer 23b. If there are irregularities on the contact surface with the adhesive layer 23b, air bubbles may appear on the surface of the adhesive layer 23b, resulting in a decrease in sealing performance. According to the seal portion 25, since adhesion with the adhesive layer 23b can be achieved by the smooth surface 25a, high sealing performance can be ensured.

[0042] The degree of smoothness of the smooth surface 25a in the seal portion 25 is not particularly limited as long as sealing performance can be ensured. For example, it is preferably 0.5 μm or less in terms of the maximum height Rz of JIS B 0601-2001 (ISO 4287-1997). Also, in FIG. 4, W S The width of the seal portion shown is preferably 1 mm or more and 5 mm or less.

[0043] [Restraining portion] The restraining portion 26 has irregularities (protrusions 26a and recesses 26b) on at least the surface that contacts the adhesive layer 23b of the support 23 among the cathode separator 15 and the anode separator 18, and restricts the movement of the support 23 by the entry of the adhesive layer 23b into the recesses 26b and the penetration of the protrusions 26a into the adhesive layer 23b. The restraining portion 26 can restrain the support 23, and it becomes possible to suppress the movement of the support 23 in the direction indicated by the straight arrow B in FIG. 4, such as dimensional changes due to thermal expansion and contraction, dimensional changes due to collisions, etc., and enhance dimensional stability. Also, the adhesiveness (adhesive strength) between the cathode separator 15 and the anode separator 18 and the support 23 can be increased by the increase in the adhesive area due to the irregularities.

[0044] The concavo-convex form of the restraint portion 26 is not particularly limited as long as it can restrict the movement of the support 23 more than the seal portion 25. For example, the forms as shown in FIGS. 6(a) to 6(c) can be cited. FIGS. 6(a) to 6(c) are diagrams schematically showing a part of the surfaces on the side of the convex portion 26a and the concave portion 26b formed on the anode separator 18 in the restraint portion 26. The same can be considered for the cathode separator 15 side.

[0045] In the example of FIG. 6(a), the anode separator 18 is formed in a wavy shape in the restraint portion 26, and concavo-convex striations are formed on the front and back thereof. Among the concavo-convex striations, the concavo-convex striations formed on the support 23 side become the convex portion 26a (convex striation) and the concave portion 26b (concave striation), respectively. In this form, the direction in which the convex portion 26a extends and the direction in which the concave portion 26b extends are substantially parallel, and the convex portion 26a and the concave portion 26b are alternately arranged in a direction orthogonal to the extending direction. Although not particularly limited, it is preferable that the convex portion 26a and the concave portion 26b are alternately arranged in the direction toward the outermost peripheral end portion closest to the fuel cell 10. Thereby, the movement of the support can be suppressed more effectively.

[0046] The sizes of the convex portion 26a and the concave portion 26b are not particularly limited, but the height of the convex portion 26a and the depth of the concave portion 26b can be 20 μm or more and 80 μm or less, and the repeating interval, that is, the pitch between adjacent convex portions 26a (or adjacent concave portions 26b) can be 0.4 mm or more and 1.5 mm or less. Also, in FIG. 4, W K The width of the restraint portion 26 shown by is preferably 1 mm or more and 5 mm or less.

[0047] In the example of FIG. 6(b), the anode separator 18 has grooves arranged at intervals on the surface on the support 23 side in the restraint portion 26, which become the concave portion 26b, and the spaces between the concave portions 26b become the convex portion 26a. Also in this example, the convex portion 26a is a convex striation and the concave portion 26b is a concave striation, and the same consideration as in (a) can be made. The groove that forms such a recess 26b can also have a fine shape, and in that case, the groove can be formed by digging with laser irradiation.

[0048] In the example of Fig. 6(c), protrusions are arranged on the surface of the anode separator 18 on the side of the support 23 in the restraint portion 26. These protrusions become the convex portions 26a, and the spaces between the convex portions 26a become the concave portions 26b. In this embodiment, the convex portion 26a is a columnar protrusion, but it is not limited to this, and it may be other shaped columns (for example, square columns, triangular columns, etc.), or conical (for example, circular cones, triangular cones, square cones) protrusions. Also, it may be wavy or have an emboss / dimple shape. The arrangement of the protrusions is not particularly limited, but they may be arranged to be aligned vertically and horizontally, or may be arranged in a staggered pattern (so-called staggered arrangement). Also, the sizes of the convex portion 26a and the concave portion 26b are not particularly limited, but the height of the convex portion 26a and the depth of the concave portion 26b can be 20 μm or more and 80 μm or less, and the repeating interval, that is, the pitch, between adjacent convex portions 26a (or between adjacent concave portions 26b) can be 0.4 mm or more and 1.5 mm or less. Also, in Fig. 4, W K The width of the restraint portion 26 shown by is preferably 1 mm or more and 5 mm or less.

[0049] In addition to the above, although not shown in the drawings, the concavo-convex form of the restraint portion 26 may be formed by a rough surface. In this case, the concavo-convex due to the surface roughness constitutes the convex portion 26a and the concave portion 26b respectively. The degree of the surface roughness is not particularly limited, but it should be at least rougher than the smooth surface 25a in the seal portion 25. Specifically, for example, it is preferably 20 μm or more and 50 μm or less in terms of the maximum height Rz of JIS B 0601-2001 (ISO 4287-1997). Such concavo-convex can be formed by press molding, shot blasting treatment, laser irradiation, etc.

[0050] [Arrangement of the sealing portion] In this embodiment, in the sealing portion 24, the seal portion 25 is disposed on the inner side (the side closer to the power generation portion 11), and the restraint portion 26 is disposed on the outer side (the side closer to the outer periphery). However, it is not limited to this, and the opposite arrangement may also be possible.

[0051] FIG. 7 is a diagram showing the position where the sealing portion 24 is disposed in the power generation unit cell 10. FIG. 7(a) represents the cathode (oxygen supply side), and FIG. 7(b) represents the anode (hydrogen supply side). In each figure, the seal portion 25 is shown by a thick line, and the restraint portion 26 is shown by a dotted line. As described above, the sealing portion 24 is disposed as necessary on the outer peripheral portion of the power generation unit cell 10 and around the fluid inlet / outlet. In the present disclosure, in the sealing portion 24, the seal portion 25 and the restraint portion 26 are provided separately and arranged side by side at different positions.

[0052] [Others] In the embodiment shown in FIG. 4, the cathode separator 15 and the anode separator 18 between the seal portion 25 and the restraint portion 26 are provided with protruding portions 24a. As will be described later, when a plurality of power generation unit cells 10 are stacked to form the fuel cell 30, an adhesive sheet for adhering adjacent power generation unit cells 10 is adhered so as to overlap the protruding portions 24a to fix the adjacent power generation unit cells 10. The protruding portion 24a does not necessarily have to be disposed between the seal portion 25 and the restraint portion 26, and may be arranged such that the seal portion 25 and the restraint portion 26 are adjacent to each other as shown in FIG. 8. In this case, the protruding portion 24a may be provided at different positions.

[0053] 2. Fuel Cell The fuel cell 30 is a member formed by stacking a plurality (about 50 to 400) of the above-described power generation unit cells 10, and collects electric power from the plurality of power generation unit cells 10. The outline of its configuration is shown in FIG. 9. The fuel cell 30 includes a stack case 31, end plates 32, a plurality of power generation unit cells 10, a current collector plate 34, and a biasing member 35.

[0054] The stack case 31 is a housing that houses a plurality of stacked power generation unit cells 10, a current collector plate 34, and a biasing member 35 inside thereof. In this embodiment, the stack case 31 is in the shape of a rectangular cylinder with one end open and the other end closed, and a plate-like piece projects to the side opposite to the opening along the edge of the opening, forming a flange 31a.

[0055] The end plate 32 is a plate-like member that closes the opening of the stack case 31. The end plate 32 is fixed to the stack case 31 so as to cover the stack case 31 with bolts, nuts, etc. at the overlapping portion with the flange 31a of the stack case 31.

[0056] The power generation unit cell 10 is as described above. A plurality of such power generation unit cells 10 are stacked. At this time, the anode separator 18 of the power generation unit cell 10 adjacent to the cathode separator 15 of one power generation unit cell 10 is arranged so as to overlap. Then, the cooling water flow path is formed by the grooves 15b of the cathode separator 15 and the grooves 18b of the anode separator 18 overlapping. An adhesive (sticking) sheet is arranged between adjacent power generation unit cells 10, and the protrusions 24a (see FIGS. 3 and 4) of adjacent power generation unit cells 10 are adhered to each other by the adhesive sheet, so that both are stably fixed.

[0057] The current collector plate 34 is a member that collects current from the stacked power generation unit cells 10. Therefore, the current collector plate 34 is arranged at each of one end and the other end of the stack of the power generation unit cells 10, with one being the positive electrode and the other being the negative electrode. Terminals (not shown) are connected to the current collector plate 34 so as to be electrically connected to the outside.

[0058] The biasing member 35 is housed inside the stack case 31 and applies a pressing force in the stacking direction to the stack of the power generation unit cells 10. Examples of the biasing member include a disc spring.

[0059] 3. Effects, etc. In the present disclosure, in the sealing portion of the power generation unit cell, a sealing portion having high sealing performance and excellent airtightness and a restraining portion for restraining the movement of the support 23 due to heat, differential pressure, impact, etc. are provided separately, so that both the sealing performance and the dimensional stability can function reliably without interfering with each other. For example, if an attempt is made to ensure the sealing performance without providing these separately, the movement of the support cannot be sufficiently restrained, and problems may occur in the shape stability and the sealing performance. On the other hand, when sealing is performed only with the uneven surfaces in order to restrain the movement of the support, air bubbles may be generated in the uneven portions, which may impair the sealing performance. In contrast, according to the present disclosure, as described above, both the sealing performance and the dimensional stability can function reliably without interfering with each other.

Explanation of reference numerals

[0060] 10 Power generation unit cell 11 Power generation portion 12 Electrolyte membrane 13 Cathode catalyst layer 14 Cathode gas diffusion layer 15 Cathode separator 16 Anode catalyst layer 17 Anode gas diffusion layer 18 Anode separator 21 Outer peripheral portion 22 Cover sheet 23 Support 23a Base material 23b Adhesive layer 24 Sealing portion 25 Sealing portion 26 Restraining portion 26a Protrusion 26b Recess 30 Fuel cell

Claims

1. A power generation unit cell comprising an electrolyte membrane, a membrane electrode assembly having catalyst layers disposed so as to sandwich the electrolyte membrane, a support disposed so as to surround the membrane electrode assembly, and a pair of separators disposed so as to sandwich the membrane electrode assembly and the support, wherein the support has a base material and adhesive layers laminated on both surfaces of the base material, the separator has a seal portion which is a smooth surface and a restraint portion having irregularities at a portion where the separator adheres to the adhesive layer of the support, on the side where the irregularities of the restraint portion adhere to the adhesive layer, the height of the convex portion and the depth of the concave portion are 20 μm or more and 80 μm or less, and the pitch of adjacent convex portions is 0.4 mm or more and 1.5 mm or less, the width of the seal portion is 1 mm or more and 5 mm or less, and the width of the restraint portion is 1 mm or more and 5 mm or less, a power generation unit cell.

2. A fuel cell in which a plurality of the power generation unit cells according to Claim 1 are stacked.

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