Manufacturing method of separator

Abstract

To provide a manufacturing method of a separator, capable of improving the producibility.SOLUTION: A manufacturing method of a separator for a fuel battery having a cooling surface in contact with a coolant at one sid and having a power generation surface in contact with a power generation body on the other side, comprises a deposition step of arranging a plurality of base materials, and performing deposition on a front surface of the base material. In the deposition step, the plurality of base materials are arranged so that parts of surfaces that become the cooling surfaces of the base materials face each other.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a separator.

Background Art

[0002] Various technologies have been proposed regarding fuel cells as disclosed in Patent Document 1.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Patent Document 1 discloses a method for manufacturing a separator for a fuel cell, in which a masking member 4 is disposed in a region other than a region that becomes a power generation body sandwiching portion 1 for sandwiching a power generation body in a metal base material 6, and a titanium film is formed using an unbalanced magnetron sputtering method. Although the film formation of the separator is generally performed over the entire power generation region (power generation body sandwiching portion), since it is necessary to perform surface treatment from both sides (gas surface side, cooling surface side) of the separator during film formation, there is room for improvement from the viewpoint of manufacturing efficiency.

[0005] The present disclosure has been made in view of the above circumstances, and a main object thereof is to provide a method for manufacturing a separator capable of improving manufacturing efficiency.

Means for Solving the Problems

[0006] That is, the present disclosure includes the following aspects. <1> A method for manufacturing a separator for a fuel cell, comprising a cooling surface in contact with a refrigerant on one side and a power generation surface in contact with a power generation body on the other side, comprising a film forming step of arranging a plurality of base materials side by side and performing film formation on the surfaces of the base materials. In the film formation step, the plurality of base materials are arranged such that a part of the surfaces that become the cooling surfaces of the respective base materials face each other. A method for manufacturing a separator characterized by this.

Advantages of the Invention

[0007] The method for manufacturing a separator of the present disclosure can improve manufacturing efficiency.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments according to the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for the implementation of the present disclosure (for example, general configurations and manufacturing processes of separators that do not characterize the present disclosure) can be grasped as design matters of those skilled in the art based on the prior art in the relevant field. The present disclosure can be implemented based on the content disclosed in this specification and common general technical knowledge in the relevant field. Also, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships. In the present disclosure, the gas supplied to the anode of the fuel cell is a fuel gas (anode gas), and the gas supplied to the cathode of the fuel cell is an oxidant gas (cathode gas). The fuel gas is mainly a gas containing hydrogen, and may be hydrogen. The oxidant gas is a gas containing oxygen, and may be oxygen, air, etc. In the present disclosure, the fuel gas and the oxidant gas are collectively referred to as a reaction gas or a gas.

[0010] In the present disclosure, there is provided a method for manufacturing a separator for a fuel cell, which includes a cooling surface in contact with a refrigerant on one side and a power generation surface in contact with a power generation element on the other side, including a film forming step of arranging a plurality of base materials side by side and forming a film on the surfaces of the base materials, wherein in the film forming step, the plurality of base materials are arranged such that a part of the surfaces of the base materials that will become the cooling surfaces face each other. A method for manufacturing a separator is provided.

[0011] Although the use of inexpensive SUS as a material for the separator of a fuel cell has been considered, in the environment where the separator is actually used, the pH of the internal fluid may decrease and SUS may be corroded. Therefore, SUS is covered by surface treatment to prevent corrosion. The surface treatment uses a process called PVD, and a Ti film and a C film are deposited on a SUS base material under vacuum. Using carbon with good conductivity on the outermost surface is excellent as a surface treatment for the separator, but the production amount per unit time is small. Since a large number of cells and separators are used in one stack, the number of equipment used increases, leading to an increase in equipment cost. In the conventional technology, there are those that perform surface treatment entirely or partially. In the case of partial film formation, the seal part is not film-formed and the power generation part (corresponding to the GDL part) is film-formed. In this case, since the area to be film-formed is large and it is necessary to perform surface treatment from both sides (gas surface side, cooling surface side) of the separator, it is necessary to place the separators one by one in one equipment for film formation. In addition, there are cases where SUS is used as a separator without surface treatment, but the passive film on the outermost surface of SUS becomes thick, the contact resistance increases, and the influence on the stack output becomes large. Therefore, in order to reduce the stack output, it is essential to apply a conductive surface treatment to the SUS surface.

[0012] In the present disclosure, a method for increasing the production amount per unit time by minimizing the range of surface treatment of the separator is proposed. On the power generation surface side (gas surface side) of the separator, corrosion of the base material is a concern. However, on the cooling surface side, as long as the resistance standard (lower than a certain resistance) is met, the performance as a fuel cell can be ensured even if the film formation is not complete on some parts. In the present disclosure, by arranging two separators such that a part of the cooling surfaces face each other (overlap), the number of base materials on which film formation can be performed at one time increases, thus improving the manufacturing efficiency.

[0013] The separator of the present disclosure includes a cooling surface in contact with a refrigerant on one side and a power generation surface in contact with a power generation body on the other side. As the separator, it may be a metal such as SUS that has been surface-treated in the film formation process. The separator collects the current generated by power generation and functions as a partition. In a fuel cell, the separator is usually arranged on both sides in the stacking direction of the power generation body so that a pair of separators sandwich the power generation body. One of the pair of separators is an anode separator, and the other is a cathode separator. The anode separator may have grooves serving as fuel gas flow paths on the surface facing the power generation body side. The cathode separator may have grooves serving as oxidant gas flow paths on the surface facing the power generation body side. The separator may have holes that constitute a manifold such as supply holes and discharge holes for allowing a fluid to flow in the stacking direction of the cell. Examples of the refrigerant include water, a mixed solvent of water and ethylene glycol, and the like.

[0014] [Film Formation Process] The film formation process is a process of arranging a plurality of base materials side by side and forming a film on the surface of the base materials. In the film formation process, the plurality of base materials are arranged such that a part of the surfaces that will become the cooling surfaces of each base material face each other. The base material may be a metal such as SUS. The separator needs to form a film on both sides (gas side, cooling water side) by surface treatment. For example, by depositing Ti and C from both sides of one separator, the formation of a Ti film and a C film is realized. When the surface treatment is PVD, a substrate (separator) is placed facing a solid evaporation source, and a film is formed on the separator. The evaporation source may be Ti and C, or other materials such as Au and Ag. Since the particles generated from the evaporation source are pulled by the bias voltage applied to the separator and collide with the separator to form a film, the surface facing the evaporation source will be the film-forming surface (the non-facing surface or the part covered by the mask will not be film-formed).

[0015] Figure 1 is a schematic diagram showing an example of the film-forming process of the present disclosure. In the present disclosure, as shown in Figure 1, it is allowed to create a film thickness gradient within the surface treatment required area so that no surface treatment is performed or the film thickness is small. At this time, by shifting the surface treatment film-forming part between the No. 1 separator and the No. 2 separator, it is possible to make the film thickness distribution uniform for the total separators and satisfy the required functions (especially resistance). Thereby, the surface treatment production volume can be increased by increasing the number of simultaneous film-forming within the same equipment.

[0016] In the present disclosure, in order to increase the production volume, the number of separators per equipment is increased by stacking the substrates of the separators for film formation. The object of stacking the substrates of the separator is the cooling surface side. When stacking the gas surface side, if a non-film-forming surface is generated by stacking the substrates of the separator, corrosion in the cell environment is a concern. By stacking the substrates of two separators, a non-film-forming surface appears, but the contact resistance between one separator and the other separator can be ensured as long as only one side is surface-treated, so the required functions can be satisfied. Figure 2 is a schematic diagram showing another example of the film-forming process of the present disclosure. As shown in Figure 2, surface treatment may be performed to ensure the total film thickness of the No. 1 separator and the No. 2 separator by forming films on half of the areas of the power generation parts on the cooling surface sides of the No. 1 separator and the No. 2 separator. When it is necessary to ensure a carbon film thickness of, for example, 15 nm or more to ensure conductivity, it is sufficient to ensure a total film thickness of 15 nm or more for the two separators.

[0017] Figure 3 is a schematic diagram showing another example of the film-forming process of the present disclosure. As shown in Figure 3, for the film-forming part by surface treatment on the cooling surface (FCC surface) side of the separator, the film-forming part is divided into a No. 1 separator and a No. 2 separator, respectively. For the part where film formation is carried out on one separator, film formation on the other separator is not necessary. By doing the above, the substrates of the separators can be stacked and film-formed. In this way, the substrates of the separators are stacked and set in the equipment for film formation, increasing the production volume per unit time.

[0018] The separator of the present disclosure is for a fuel cell. The fuel cell may have only one single cell (cell, fuel cell cell) of the fuel cell, or may be a fuel cell stack (stack) in which a plurality of cells are stacked. In the present disclosure, both the fuel cell cell and the fuel cell stack may be referred to as a fuel cell in some cases. The number of cells stacked in the fuel cell stack is not particularly limited, and may be, for example, 2 to several hundred.

[0019] The cell may have a power generation body. The shape of the power generation body may be rectangular in plan view. The power generation body may be a membrane electrode assembly (MEA) including an electrolyte membrane and two electrodes. The electrolyte membrane may be a solid polymer electrolyte membrane. Examples of the solid polymer electrolyte membrane include fluorine-based electrolyte membranes such as thin films of perfluorosulfonic acid containing moisture, and hydrocarbon-based electrolyte membranes. The electrolyte membrane may be, for example, a Nafion membrane (manufactured by DuPont). One of the two electrodes is an anode (fuel electrode), and the other is a cathode (oxidant electrode). The electrode includes a catalyst layer and may optionally include a gas diffusion layer. The power generation body may be a membrane electrode gas diffusion layer assembly (MEGA). The catalyst layer includes a catalyst, and the catalyst may include a catalyst metal that promotes an electrochemical reaction, an electrolyte having proton conductivity, a carrier having electron conductivity, and the like. As the catalyst metal, for example, platinum (Pt), an alloy composed of Pt and other metals (for example, a Pt alloy mixed with cobalt, nickel, etc.) can be used. The catalyst metal used as the cathode catalyst and the catalyst metal used as the anode catalyst may be the same or different. As the electrolyte, a fluororesin or the like may be used. As the fluororesin, for example, Nafion solution or the like may be used. The above catalyst metal is supported on a carrier, and in each catalyst layer, the carrier supporting the catalyst metal (catalyst-supported carrier) and the electrolyte may be mixed. Examples of the carrier for supporting the catalyst metal include carbon materials such as commercially available carbon. The gas diffusion layer may be a conductive member having pores or the like. Examples of the conductive member include carbon porous bodies such as carbon cloth and carbon paper, and metal porous members such as metal mesh and foamed metal. The cell may include an insulating resin frame disposed outside (outer periphery) in the plane direction of the membrane electrode assembly between the anode separator and the cathode separator. The resin frame is formed into a plate-like and frame-like shape using a thermoplastic resin, and seals the space between the anode separator and the cathode separator while holding the membrane electrode assembly in its central region. As the resin frame, for example, resins such as PE, PP, PET, and PEN can be used. The resin frame may be a three-layer sheet composed of three layers with an adhesive layer disposed on the surface layer.

[0020] The fuel cell stack may have gaskets, resin sheets, etc. for sealing each gas between cells and the like.

Claims

【Claim 1】 A method for manufacturing a separator for a fuel cell, comprising a cooling surface in contact with a refrigerant on one side and a power generation surface in contact with a power generation body on the other side, comprising a film forming step of arranging a plurality of base materials side by side and forming a film on the surface of the base materials, In the film forming step, the plurality of base materials are arranged such that a part of the surfaces of the base materials that will become the cooling surfaces face each other. A method for manufacturing a separator, characterized by this.

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