JP2022127351A - Method for manufacturing fuel battery cell - Google Patents

Abstract

To suppress a resin from entering into a gas flow channel in pressing.SOLUTION: A method for manufacturing a fuel battery cell (10) includes the steps of: arranging a seal material (14) on a first sheet (21) in a state of sandwiching between a pair of separators (12 and 13), then covering the seal material sandwiched between the pair of separators with a second sheet (22), and thereby forming a space (23) sealed between the first sheet and the second sheet; and thermally pressing the pair of separators while vacuuming the space. In at least a part of a region around a region where the seal material is arranged of the first sheet, a projection (21a) having a height higher than a height of the gas flow channel is formed. The second sheet covers the seal material sandwiched between the pair of separators and the projection.SELECTED DRAWING: Figure 4

Description

The present invention relates to the technical field of manufacturing methods for fuel cells.

As a manufacturing method of this type, for example, a manufacturing method has been proposed in which a sealing material is sandwiched between a pair of separators and hot-pressed with a press die (see Patent Document 1).

JP 2020-013734 A

The sealing material described in Patent Document 1 is composed of a membrane electrode assembly (MEA) and a frame-shaped resin frame that fixes the periphery of the membrane electrode assembly. Depending on the resin used for the resin frame, there is a technical problem that the resin may enter the gas flow path for supplying the reaction gas to the membrane electrode assembly when hot pressing is performed. .

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel cell manufacturing method capable of suppressing resin from entering a gas flow path during pressing.

A method for manufacturing a fuel cell according to an aspect of the present invention includes a sealing material having a frame-shaped resin frame for fixing a membrane electrode assembly and a peripheral edge portion of the membrane electrode assembly, and reacting gas to the membrane electrode assembly. and a pair of separators sandwiching the sealing material, wherein the sealing material is sandwiched between the pair of separators, and the first sheet a step of forming a sealed space between the first sheet and the second sheet by covering the sealing material sandwiched between the pair of separators with a second sheet after placing the sealing material on the separator; and hot-pressing the pair of separators while evacuating the space, wherein the height of the gas flow path is formed in at least a part of the region of the first sheet surrounding the region where the sealing material is arranged. A convex portion having a height higher than the height is formed, and the second sheet covers the sealing material sandwiched between the pair of separators and the convex portion.

1 is an exploded perspective view of a fuel cell according to an embodiment; FIG. 1 is an enlarged cross-sectional view showing an enlarged part of a fuel cell according to an embodiment; FIG. It is process sectional drawing which shows a part of manufacturing process of the fuel cell which concerns on embodiment. 4 is a process cross-sectional view showing a process following the process shown in FIG. 3; FIG. 4 is a flow chart showing manufacturing steps of the fuel cell according to the embodiment.

An embodiment of a fuel cell manufacturing method will be described with reference to FIGS. 1 to 5. FIG. First, a fuel cell manufactured by a manufacturing method according to an embodiment will be described with reference to FIGS. 1 and 2. FIG.

In FIG. 1, a fuel cell 10 includes a membrane electrode gas diffusion layer assembly (MEGA) 11, a cathode side separator 12, an anode side separator 13, and a sealing material 14. It is configured. The membrane electrode gas diffusion layer assembly 11 is hereinafter referred to as "MEGA 11" as appropriate.

The MEGA 11 has a membrane electrode assembly (not shown), a cathode-side gas diffusion layer, and an anode-side gas diffusion layer. The MEGA 11 has a structure in which a membrane electrode assembly is sandwiched between a cathode-side gas diffusion layer and an anode-side gas diffusion layer. That is, the cathode-side gas diffusion layer is arranged on the cathode-side separator 12 side of the membrane electrode assembly, and the anode-side gas diffusion layer is arranged on the anode-side separator 13 side of the membrane electrode assembly.

The sealing material 14 has a frame-shaped resin frame that fixes the peripheral edge of the MEGA 11 . The sealing material 14 may be configured to contain, for example, a thermoplastic resin such as an olefin resin. Various existing modes can be applied to the MEGA 11, the cathode-side separator 12, the anode-side separator 13, and the sealing material 14, so detailed description thereof will be omitted.

As shown in FIG. 2, the cathode-side separator 12 is bonded to the sealing material 14, thereby forming an oxidizing gas flow path through which air as an oxidizing gas flows along the surface of the cathode-side gas diffusion layer that constitutes the MEGA 11. 12a is formed. Also, by joining the anode-side separator 13 to the sealing material 14 , a fuel gas flow path 13 a is formed along the surface of the anode-side gas diffusion layer that constitutes the MEGA 11 , through which hydrogen as a fuel gas flows. In FIG. 2, a portion surrounded by a dashed circle C is called a "flange portion".

The fuel cell 10 as described above can be manufactured by hot pressing using a mold (not shown), for example, in a state in which the sealing material 14 is sandwiched between the cathode-side separator 12 and the anode-side separator 13. be.

Here, according to the studies of the inventors of the present application, the following matters have become clear. That is, if a relatively low-cost olefin-based resin is used for the sealing material 14, a portion of the sealing material 14 will collapse due to the temperature and load during hot pressing, and the oxidizing gas flow path 12a and The resin forming the sealing material 14 may enter at least part of the fuel gas flow path 13a. On the other hand, it is conceivable to use an engineering plastic resin having excellent heat resistance for the sealing material 14 . However, since engineering plastic resins are relatively expensive, there is a problem that production costs increase. On the other hand, if at least one of the temperature and the load during hot pressing is lowered, there is a problem that adhesion failure may occur in the fuel cells 10 .

In order to solve the above problem, the inventor of the present application covered the sealing material 14 sandwiched between the cathode-side separator 12 and the anode-side separator 13 (hereinafter referred to as an "assembly" as appropriate) with a sheet, and covered with the sheet. It was decided to adopt a vacuum press that heats the assembly while decompressing the space (that is, the space in which the assembly is arranged). However, a new problem arises in that the flange portion (see FIG. 2) is crushed by the sheet covering the assembly during vacuum pressing.

Therefore, in the fuel cell manufacturing method according to the present embodiment, as shown in FIG. 3, at least part of the region surrounding the region where the assembly 100 is arranged has a height higher than the height of the flange portion. A sheet 21 on which convex portions 21a are formed is used.

Specifically, first, the assembly 100 is placed on the seat 21 . At this time, for example, the central portion of the assembly 100 is arranged on the convex portion 21b of the sheet 21 . The convex portion 21 b is for stably placing the assembly 100 on the seat 21 . The height of the convex portion 21b may be set according to, for example, the height of the oxidant gas channel 12a or the fuel gas channel 13a. Next, the assembly 100 is covered with the sheet 22 after the pressing body 24 is placed on the side of the assembly 100 opposite to the sheet 21 side. As a result, a closed space 23 is formed by the sheets 21 and 22 .

Next, the assembly 100 is heated while the space 23 is evacuated (in other words, the pressure is reduced), so that the cathode side separator 12, the sealing material 14 (MEGA 11) and the anode side separator 13 are adhered. At this time, as shown in FIG. 4, since the sheet 21 is provided with the projections 21a, it is possible to prevent the sheet 22 from crushing the flange portion when the space 23 is vacuumed. After that, the assembly 100 (that is, the fuel cell 10) is cooled, and the pressure in the space 23 is returned to normal pressure.

A method for manufacturing a fuel cell according to this embodiment will be described with reference to the flow chart of FIG. In FIG. 5, a sheet 21 having projections 21a is placed on a mounting table (not shown) of a vacuum press (step S101). Next, the cathode-side separator 12, the anode-side separator 13, and the sealing material 14 including the MEGA 11 are placed on the sheet 21, that is, the assembly 100 is placed (step S102).

Next, the sheet 22 is installed so as to cover the assembly 100 (step S103). Next, the space 23 formed by the sheet 21 and the sheet 22 is decompressed (step S104). In parallel with the process of step S104, the assembly 100 is heated (step S105). After cooling the assembly 100, the pressure in the space 23 is returned to normal pressure. After that, the fuel cell 10 is taken out from the vacuum press (step S106).

(technical effect)
When the assembly 100 is hot-pressed using a mold, for example, the entire assembly 100 may be deformed due to variations in the thickness of the components of the assembly 100 (sealing material 14, etc.) and installation tolerances of the mold. It is difficult to apply pressure evenly. For this reason, there is a possibility that the resin forming the sealing material 14 may enter at least part of the oxidant gas channel 12a and the fuel gas channel 13a, or that the fuel cell 10 may have poor adhesion. On the other hand, in the vacuum press, since the entire assembly 100 can be uniformly pressurized, for example, it is possible to suppress the resin from entering the oxidizing gas flow path 12a and the fuel gas flow path 13a during pressing. .

Particularly in this embodiment, by using the sheet 21 having the projections 21a formed in the vacuum press, it is possible to suitably suppress the flange from being crushed by the sheet 22 during pressing. Therefore, according to the method of manufacturing a fuel cell according to the present embodiment, the assembly 100 is appropriately crimped while using a relatively low-cost thermoplastic resin such as an olefin-based resin as the sealing material 14 to produce fuel. A battery cell 10 can be manufactured.

Aspects of the invention derived from the embodiments described above will be described below.

A method for manufacturing a fuel cell according to an aspect of the invention includes a membrane electrode assembly, a sealing material having a frame-shaped resin frame for fixing a peripheral portion of the membrane electrode assembly, and a reactant gas in the membrane electrode assembly. and a pair of separators sandwiching the sealing material, wherein the sealing material is sandwiched between the pair of separators, and the first sheet a step of forming a sealed space between the first sheet and the second sheet by covering the sealing material sandwiched between the pair of separators with a second sheet after placing the sealing material on the separator; and hot-pressing the pair of separators while evacuating the space, wherein the height of the gas flow path is formed in at least a part of the region of the first sheet surrounding the region where the sealing material is arranged. A convex portion having a height higher than the height is formed, and the second sheet covers the sealing material sandwiched between the pair of separators and the convex portion.

In the above-described embodiment, the "cathode-side separator 12 and anode-side separator 13" correspond to an example of "a pair of separators", and the "oxidant gas channel 12a" and the "fuel gas channel 13a" correspond to the "gas flow channel 12a". The "sheet 21" corresponds to an example of the "first sheet", the "sheet 22" corresponds to an example of the "second sheet", and the "convex portion 21a" corresponds to an example of the "convex portion". corresponds to an example of

The present invention is not limited to the above-described embodiments, and can be modified as appropriate within the scope of the gist or idea of the invention that can be read from the scope of claims and the entire specification. is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10... Fuel battery cell 11... MEGA 12... Cathode side separator 12a... Oxidizing gas flow path 13... Anode side separator 13a... Fuel gas flow path 14... Sealing material 21, 22... Sheet 21a, 21b... convex part, 23... space, 24... pressurizing body, 100... assembly

Claims (1)

A membrane electrode assembly, a sealing material having a frame-shaped resin frame for fixing a peripheral portion of the membrane electrode assembly, and a gas flow path for supplying a reaction gas to the membrane electrode assembly, the seal comprising: A method for manufacturing a fuel cell comprising a pair of separators sandwiching a material,
After placing the sealing material sandwiched between the pair of separators on the first sheet, the sealing material sandwiched between the pair of separators is covered with a second sheet, whereby the first sheet and the first sheet are separated. forming a closed space between the two sheets;
heat-pressing the pair of separators while evacuating the space;
including
a convex portion having a height higher than the height of the gas flow path is formed on at least a part of a region of the first sheet surrounding a region where the sealing material is arranged;
The method of manufacturing a fuel cell, wherein the second sheet covers the sealing material and the protrusion sandwiched between the pair of separators.

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