Fuel cell, fuel cell device, and method of manufacturing fuel cell device

Abstract

To provide a fuel cell, a fuel cell device, and a method for manufacturing the fuel cell device in which a membrane electrode assembly and a gas diffusion layer are not thermocompressed to prevent displacement of the gas diffusion layer.SOLUTION: A fuel cell 50 includes a membrane electrode assembly 11 obtained by forming catalyst layers 12 on both sides of an electrolyte membrane 16, gas diffusion layers 14 arranged on both sides of the membrane electrode assembly 11, a pair of separators 17 sandwiching the membrane electrode assembly 11 via the gas diffusion layers 14 on both sides, a plurality of grooves 18 formed in the contact surface of the separator 17 with the gas diffusion layer 14, a protruding portion 19 formed along the grooves 18 between the grooves 18, a gasket 21 disposed on the separator 17 and surrounding the catalyst layer 12 and the gas diffusion layer 14, a pair of guide portions 22 formed on both longitudinal sides of the gas diffusion layer 14 and projecting toward the separator 17, and guide bending portions 22a that are fitted to the corner edges 24 of the ends of the protruding portions 19 arranged on both outermost sides and that extend the guide portion 22 to such an extent that the tips do not block the respective grooves 18.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] FIELD OF THE INVENTION An embodiment of the present invention relates to a cell in which a gas diffusion layer is laminated on a membrane electrode assembly, a fuel cell device, and a method for manufacturing the same. [Background technology]

[0002] A fuel cell device is constructed by stacking a large number of stacks called fuel cell units or single cells. A fuel cell is constructed by stacking an anode separator, an anode gas diffusion layer (GDL), a membrane electrode assembly (MEA), a cathode GDL, and a cathode separator in this order.

[0003] Because the GDL is molded to fit the size of the electrode surface of the MEA, unlike other plates, it cannot be secured with positioning pins on the periphery, making it prone to misalignment. Therefore, to improve assembly, the MEA and GDL have traditionally been integrated, and the outer periphery of the MEA is secured in position with positioning pins when stacked. To integrate the MEA and GDL, for example, a method is used in which the MEA and GDL are bonded together by thermocompression bonding, thereby increasing the adhesiveness of the polymer electrolyte (ionomer) contained in the catalyst layer of the MEA. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-156820 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the conventional techniques described above have the problem that the thermocompression bonding can cause thermal deformation or physical property changes in the MEA, which can prevent the expected power generation performance. Furthermore, when gaskets are used for positioning, the thermocompression bonding sometimes results in insufficient bonding at the required locations.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a fuel cell, a fuel cell device, and a method for manufacturing a fuel cell device in which the membrane electrode assembly and the gas diffusion layer are not thermocompression bonded to each other, thereby preventing displacement of the gas diffusion layer. [Means for solving the problem]

[0007] The fuel cell according to this embodiment includes a membrane electrode assembly formed by forming catalyst layers on both sides of an electrolyte membrane, gas diffusion layers disposed on both sides of the membrane electrode assembly, and Membrane electrode assembly a pair of separators sandwiching the membrane electrode assembly via the gas diffusion layers on both sides; a plurality of grooves formed on the contact surfaces of the separators with the gas diffusion layers; Multiple Formed between grooves Multiple a ridge portion; and a gasket disposed on the separator and surrounding the catalyst layer and the gas diffusion layer. a second protrusion formed along the outermost protrusion in the width direction of the plurality of protrusions and formed in the longitudinal direction of the gas diffusion layer between the gasket and the outermost protrusion; A pair of guide portions, outermost The protruding portion is fitted to the corner edge of the end of the protruding portion, and the tip of the protruding portion is The outermost groove in the short direction among the plurality of grooves and a guide bend portion that extends the guide portion to a range that does not block the opening. As a result, the guide portion and the guide bent portion provided on the outer side of the outermost convex ridge portion position the gas diffusion layer on the separator without thermocompression bonding.

[0008] Furthermore, a manufacturing method of a fuel cell device according to this embodiment includes the steps of: positioning a separator having a surface on which a plurality of ridges that define a plurality of grooves are formed, by inserting a positioning pin into an alignment hole of the separator; laminating a gas diffusion layer on the surface on which the plurality of ridges are formed; and laminating a gas diffusion layer on the surface on which the plurality of ridges are formed, the gas diffusion layer being provided along the outermost ridge in the short side direction of the plurality of ridges, The separator is disposed so as to surround the gas diffusion layer.The method includes the steps of: fitting a pair of guide portions formed in the longitudinal direction of the gas diffusion layer between the gasket and the outermost ridge portion to the outside of the longer sides of the outermost ridge portion; fitting guide bent portions that extend the guide portions to corner edges of the ends of the outermost ridge portion to an extent that their tips do not block the outermost groove in the shorter direction among the plurality of grooves; and positioning the membrane electrode assembly by inserting the positioning pins into the alignment holes of the membrane electrode assembly formed by forming catalyst layers on both sides of the electrolyte membrane. Thus, the gas diffusion layer is positioned on the separator by the guide portions and the guide bent portions provided outside the outermost ridge portion without thermocompression bonding. [Effects of the Invention]

[0009] The present invention provides a fuel cell, a fuel cell device, and a method for manufacturing a fuel cell device in which the membrane electrode assembly and the gas diffusion layer are not thermocompression bonded together, preventing displacement of the gas diffusion layer. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an exploded perspective view of a fuel cell device according to an embodiment of the present invention, and a perspective view of a fuel cell device in which the fuel cell device cells are stacked. [Figure 2] 2 is an enlarged view of the portion where the gas diffusion layer is fitted to the separator in the fuel cell shown in FIG. 1. FIG. [Figure 3] FIG. 2 is a diagram showing a separator as viewed from the side of the surface in contact with a gas diffusion layer. [Figure 4] A diagram showing the guide portion of the gas diffusion layer on the separator. [Figure 5] 2 is a cross-sectional view of the fuel cell according to the embodiment, taken along the short side of the central portion thereof; FIG. [Figure 6] 4 is a flowchart illustrating a method for manufacturing a fuel cell device. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0012] First, a fuel cell device (hereinafter simply referred to as a "fuel cell") 50 according to an embodiment and a fuel cell unit 10 constituting this fuel cell 50 will be outlined with reference to FIG. Fig. 1 is a perspective view of a fuel cell 50 according to an embodiment of the present invention. Fig. 1 also shows an exploded perspective view of one fuel cell unit 10, a so-called single cell 10, taken out of the fuel cell 50.

[0013] As shown in FIG. 1, the fuel cell 50 has a plurality of stacked unit cells 10. This stack of unit cells 10 is sandwiched between end plates 51 at both ends in the stacking direction, and these end plates 51 are fixed together by bolting them together with connecting bars (not shown). Also, although not shown, a supply passage and a fuel gas discharge passage are provided to form the fuel cell 50. In a large-capacity fuel cell 50 required for electric vehicles and the like, several tens or more of unit cells 10 are stacked. The unit cell 10 according to the embodiment can be applied to fuel cells 50 of either a water-cooled type or an air-cooled type.

[0014] The unit cell 10 according to the embodiment has an arrangement structure in which a membrane electrode assembly (MEA) 11 is sandwiched between separators 17 with a gas diffusion layer (GDL) 14 interposed therebetween. MEA 11 is configured by arranging an anode catalyst layer made up of an anode supporting a catalyst and an air cathode catalyst layer made up of an air cathode supporting a catalyst on one side of electrolyte membrane 16, respectively. Alignment holes 13 and 23 are provided in the MEA 11 and the separator 17. Positioning pins 15 are inserted into the alignment holes 13 and 23, and the MEA 11 and the separator 17 are positioned relative to each other.

[0015] It should be noted that the "MEA" in the embodiment does not include the GDL 14. The GDL 14 and separator 17 are referred to as the fuel GDL and anode separator when placed on the anode catalyst layer side, and as the air GDL and cathode separator when placed on the air electrode catalyst layer side, but no particular distinction is made in this embodiment. In other words, the structural features of the GDL 14 and separator 17 described below can be provided on either the anode or cathode side, as appropriate. The separator 17 referred to here can also include end plates 51.

[0016] 2 is an enlarged view of the portion of the unit cell 10 shown in FIG. 1 where the GDL 14 is fitted to the separator 17. As shown in FIG. FIG. 3 is a view showing the separator 17 as seen from the contact surface side with the GDL 14. As shown in FIG. The separator 17 is made of a metal plate such as a steel plate, a stainless steel plate, an aluminum plate, a plated steel plate, or a titanium steel plate, or carbon.

[0017] 2 and 3, a plurality of grooves 18 and protruding portions 19 are formed along these grooves 18 and between each groove 18 by, for example, press working on the contact surface of the separator 17 with the GDL 14. Gases such as oxidant gas, hydrogen gas, and water vapor flow through these grooves 18. The GDL 14 is a porous, flexible sheet-like member made of carbon paper, carbon cloth, etc. The GDL 14 diffuses the hydrogen gas and oxidant gas supplied to the separator 17 in strips and supplies them to the MEA 11 uniformly.

[0018] In addition, a gasket 21 is disposed between the separator 17 and the MEA 11 so as to surround the catalyst layer 12 and the GDL 14, thereby ensuring airtightness of the reaction space 28. In the unit cell 10 according to the embodiment, the GDL 14 is positioned by utilizing the gap between the gas flow path area 20, which is formed by the grooves 18 and the ridges 19, and the gasket 21 in particular. Specifically, the GDL 14 is formed to have approximately the same size as the gas flow path area 20. Furthermore, as shown in Fig. 2, a pair of guide portions 22 are formed on both longitudinal sides of the GDL 14 so as to protrude toward the separator 17 side.

[0019] When the GDL 14 is placed on the separator 17, this guide portion 22 contacts the convex rib portions (hereinafter referred to as the "outermost convex rib portions") 19a located on both outermost sides of the gas flow path range 20 from the outside, and serves as a guide to determine the short-side position of the GDL 14 on the separator 17.

[0020] It is not necessary for both guide portions 22 of a pair to be in contact with the ridge portion 19 at the same time. That is, the distance between the guide portions 22 in the lateral direction may be slightly wider than the gas flow path range 20, allowing for slight misalignment of the GDL 14 in the lateral direction. Furthermore, the guide portions 22 can be formed easily by drilling, but they may also be formed by bending the edges or by bonding a separate member. Furthermore, the guide portions 22 do not necessarily have to be provided over the entire longitudinal area of the outermost ridge portion 19a.

[0021] 2 and 3, the inner periphery of the gasket 21 is often provided with a protrusion 21a that protrudes toward the outermost ridge portion 19a. Because the GDL 14 is a low-rigidity sheet, it is preferable to use the protrusion 21a of the gasket 21 in addition to positioning using the corner edge 24 of the ridge portion 19. Therefore, it is desirable to provide a recess 26 in the guide portion 22 so that the protrusion 21a can fit into it. By increasing the number of fitting points of the GDL 14, it is possible to position it sequentially from one side to the other, making the work easier and more accurate.

[0022] The guide portion 22 is extended by a guide bent portion 22 a formed integrally with the guide portion 22 . Here, FIG. 4 is a diagram showing the guide portion 22 of the GDL 14 displayed on the separator 17. As shown in FIG. 4, the guide bent portion 22a is fitted onto the corner edge portion 24 at the end of the outermost convex ridge portion 19a, and extends the guide portion 22 to a range where the tip does not block any of the grooves 18.

[0023] Specifically, for example, if the end of outermost ridge 19a is composed of arcuate portion 19a1 and linear portion 19a2, guide bend 22a covers the outer side surface of arcuate portion 19a1, and its tip is located midway along linear portion 19a2. This guide bend 22a enables GDL 14 to be positioned in the longitudinal direction of separator 17, and also protects corner edge 24 of outermost ridge 19a from dirt.

[0024] Furthermore, by stopping the tip of the guide bend portion 22a midway along the straight portion 19a2, even if the guide bend portion 22a is deformed due to pressure on the guide bend portion 22a by the separator 17, the structure does not impede the flow of the gas that is supplied and flows in. The guide bends 22a may be provided at four locations corresponding to the four corners of the gas flow path range 20, or may be provided only at the corners of the diagonal of the gas flow path range 20.

[0025] 5 is a cross-sectional view of the central portion of the unit cell 10 according to the embodiment cut along the short side direction, with the catalyst layer 12 not shown in FIG. As shown in Fig. 5, the width of the guide portion 22 of the GDL 14 is desirably designed to be equal to or smaller than the gap between the gasket 21 and the ridge portion 19 of the separator 17. By fitting the guide portion 22 into the gap between the gasket 21 and the ridge portion 19, the pressure loss in this gap increases. This makes it possible to suppress a decrease in power generation performance due to gas leakage to parts of the MEA 11 other than the catalyst layer.

[0026] 5, it is desirable that the top surface 22b of the guide portion 22 abuts against the flat surface of the separator 17. By abutting the top surface 22b of the guide portion 22, the airtightness inside the reaction space 28 is improved and the outflow of gas can be suppressed. Furthermore, if a further effect of reducing gas outflow is desired, the height of the guide portion 22 can be made higher than the height of the ridge portion 19 to improve adhesion. However, if the only function expected is to position the GDL 14, there is no restriction on the height of the guide portion 22.

[0027] Next, a method for manufacturing the fuel cell 50 will be described with reference to the flowchart of FIG. Hereinafter, each step will be abbreviated as "S." The same abbreviation will be used in the drawings. In manufacturing the fuel cell 50, as shown in FIG. 6, first, for example, two positioning pins 15 are placed at a distance from each other (S11).

[0028] Next, the separator 17 is positioned by inserting the positioning pin 15 into the positioning hole 23 of the separator 17, with the surface on which the plurality of ridges 19 are formed (S12). Then, the GDL 17 is laminated on the surface on which the ridge portion 19 is provided (S13).

[0029] Next, the pair of guide portions 22 are fitted onto the outer sides of the longer sides of both outermost ridge portions 19a to position the GDL 14 (S14). At this time, the guide bent portions 22a are fitted into the corner edge portions 24 at the ends of both outermost ridge portions 19a, and the longitudinal positioning is also determined. Next, the positioning pins 15 are inserted into the positioning holes 13 of the MEA 11 to position the MEA 11 (S15). Then, the GDL 14 is stacked so that the surface of the GDL 14 without the guide portion 22 comes into contact with the MEA 11 (S16).

[0030] Next, the positioning holes 23 of the separator 17 are inserted onto the positioning pins 15, and the separator 17 is stacked on the GDL 14 (S17). Then, similar to step S14, the GDL 14 is positioned by the guide portion 22 including the guide bent portion 22a (S18), and the manufacturing of the unit cell 10 is completed (END).

[0031] As described above, the fuel cell 50 or the single cell 10 according to this embodiment can prevent the GDL 17 from shifting in position without thermocompression bonding the MEA 11 and the GDL 17 together. Eliminating the need for thermocompression bonding not only directly reduces the number of steps and costs, but also eliminates the need to prepare jigs for subassembly and hot press machines for thermocompression bonding. Furthermore, since it is possible to suppress changes in the physical properties of the catalyst layer 12 of the MEA 11 due to thermocompression bonding, it is possible to prevent changes in the physical properties such as thermal decomposition of the polymer electrolyte. Furthermore, since the thermal deformation of the MEA 11 can be prevented, the thermal deformation of the electrolyte membrane 16 and reinforcing materials such as PEN that constitute the MEA 11 can also be prevented.

[0032] Although an embodiment of the present invention has been described, this embodiment is presented as an example and is not intended to limit the scope of the invention. The embodiments may be embodied in various other forms, and various omissions, substitutions, modifications, and combinations may be made without departing from the spirit of the invention. The embodiments and their modifications are included in the scope of the inventions and their equivalents as defined in the claims, as well as in the scope and spirit of the inventions.

[0033] For example, in the separator, the single cell has been described as having a shape in which the gas flow direction is the longitudinal direction, but the gas flow direction may be the transverse direction. [Explanation of symbols]

[0034] 10...fuel cell (single cell), 11...membrane electrode assembly (MEA), 12...catalyst layer, 13...MEA alignment hole, 14...gas diffusion layer (GDL), 15...positioning pin, 17...separator, 18...groove, 19 (19a)...convex rib portion, 19a (19a1, 19a2)...outermost rib portion (arc portion, straight portion), 20...gas flow path area, 21 (21a)...gasket (protrusion), 22 (22a, 22b)...guide portion (guide bend portion, top surface of guide portion), 23...GDL alignment hole, 24...corner edge portion, 26...recess, 28...reaction space, 50...fuel cell, 51...end plate

Claims

1. a membrane electrode assembly formed by forming catalyst layers on both sides of an electrolyte membrane; gas diffusion layers disposed on both sides of the membrane electrode assembly; a pair of separators sandwiching the membrane electrode assembly via the gas diffusion layers on both sides of the membrane electrode assembly; a plurality of grooves formed on the contact surface of the separator with the gas diffusion layer; a plurality of ridges formed between the plurality of grooves; a gasket disposed on the separator and surrounding the catalyst layer and the gas diffusion layer; a pair of guide portions provided along an outermost ridge portion in a lateral direction of the plurality of ridge portions, and formed in a longitudinal direction of the gas diffusion layer between the gasket and the outermost ridge portion; a guide bent portion that is fitted into a corner edge portion of an end of the outermost convex rib portion and whose tip extends the guide portion to a range that does not block the outermost groove in the short side direction among the plurality of grooves, A fuel cell characterized in that the gas diffusion layer is positioned on the separator without thermocompression bonding by the guide portion and the guide bent portion provided on the outside of the outermost convex ridge portion.

2. the end of the outermost convex ridge portion is composed of an arc portion and a straight portion, The fuel cell according to claim 1 , wherein the tip of the guide bent portion is located midway through the straight portion.

3. a protrusion provided on the gasket and protruding toward the outermost convex ridge portion; The fuel cell according to claim 1 or 2, further comprising a recess provided in the guide portion and adapted to fit onto the protrusion.

4. The fuel cell according to any one of claims 1 to 3, wherein a top surface of the guide portion abuts against a flat surface of the separator.

5. A fuel cell device comprising the fuel cell according to any one of claims 1 to 4.

6. a step of inserting a positioning pin into an alignment hole of a separator having a surface on which a plurality of protrusions that define a plurality of grooves are formed, thereby positioning the separator; laminating a gas diffusion layer on the surface on which the plurality of ridge portions are provided; a step of fitting a pair of guide portions formed in the longitudinal direction of the gas diffusion layer between a gasket arranged on the separator so as to surround the gas diffusion layer and the outermost ridge portion, the guide portions being provided along an outermost ridge portion in a lateral direction of the plurality of ridge portions, to the outer sides of the outermost ridge portion; a step of fitting a guide bent portion, the guide portion being extended to a range where a tip end does not block the outermost groove in the short direction among the plurality of grooves, into a corner edge portion of an end of the outermost convex rib portion; and a step of inserting the positioning pins into the alignment holes of a membrane electrode assembly formed by forming catalyst layers on both sides of an electrolyte membrane to position the membrane electrode assembly, A method for manufacturing a fuel cell device, wherein the gas diffusion layer is positioned on the separator by the guide portion and the guide bent portion provided on the outside of the outermost convex ridge portion without thermocompression bonding.

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