JP6978057B2 - Separator manufacturing method for fuel cells and film forming equipment - Google Patents

Description

The present invention relates to a method for manufacturing a separator for a fuel cell and a film forming apparatus used for the manufacturing.

As a separator for a fuel cell (hereinafter, also simply referred to as a separator), as shown in Patent Document 1, a gas barrier film such as DLC is formed on the surface of a base material, and a conductive resin film such as CC composite is formed on the gas barrier film such as DLC. There is something that has been done.

As a method for mass-producing such separators, conventionally, a so-called cassette-to-cassette type film forming apparatus has been used to intermittently process a plurality of substrates. Specifically, a plurality of substrates having a concave groove processed in advance are arranged on a substrate larger than the substrate, and the substrate is DLC coated in vacuum plasma while being conveyed in the film forming apparatus, and after processing. Paint the CC composite in the air.

However, since the above-mentioned cassette-to-cassette method results in intermittent film formation, there are problems that the film formation speed is slow and the production efficiency is low.
Further, the film forming apparatus is divided into a plurality of rooms into which various gases are introduced for each process, and these rooms are intermittently transported with the base material placed on the substrate. It is necessary to provide an expensive gate valve between the rooms, and there is also a problem that the film forming apparatus becomes expensive.

Japanese Unexamined Patent Publication No. 2016-170177

Therefore, the present invention has been made to solve the above-mentioned problems at once, and its main problem is to improve the film forming speed and the manufacturing efficiency without making the film forming apparatus expensive. It is something to do.

That is, in the method for manufacturing a separator for a fuel cell according to the present invention, a gas barrier film forming process for forming a gas barrier film on at least one surface of a base material and a recess for forming a groove in the base material after the gas barrier film forming process. It is a method characterized by comprising a groove forming process.

For example, the base material on which the concave groove is formed cannot be wound on a transport roller, but in the above method, a gas barrier film is formed on the base material before the concave groove is formed, so that the sheet is formed in the film forming apparatus. The shape-like base material can be conveyed by, for example, feeding or winding by a conveying roller. As a result, a so-called roll-to-roll type film forming apparatus can be used instead of the cassette-to-cassette type, so that the film forming speed can be improved and the manufacturing efficiency can be improved by continuously manufacturing the separator.
Further, since the sheet-shaped base material is conveyed in the film forming apparatus, it is sufficient that a small gap is formed in the partition of each room partitioned for each process so that the sheet can pass through. As a result, for example, by providing a pressure welding roller in the partition of each room to convey the sheet-shaped base material, it is possible to prevent different types of gas from flowing between the rooms without providing an expensive gate valve. , The film forming apparatus can be made inexpensive.

Examples of the base material include aluminum (Al), titanium (Ti), iron (Fe), magnesium (Mg), nickel (Ni), and alloys containing these metals, which have at least one kind of metal. Be done.

If the gas barrier film is too thin, a sufficient effect of the gas barrier film cannot be obtained, and if it is too thick, the film forming time becomes long, which is disadvantageous in terms of productivity.
Therefore, the thickness of the gas barrier film is preferably 10 nm or more and 500 nm or less.
In this case, the film formation time does not become long, and the effect of the gas barrier film can be fully exerted while ensuring productivity.

Although the above-mentioned gas barrier coating has excellent gas barrier properties, on the other hand, it is difficult to completely cover defective parts such as many irregularities and pinholes existing on the surface of the base material, and these defective parts have corrosion resistance. It becomes a big factor of the decrease of.
Therefore, it is preferable to further include a conductive resin film forming process for forming the conductive resin film on the surface of the gas barrier film.
By covering the surface of the gas barrier coating with the conductive resin coating, the above-mentioned defective portion can be substantially sealed, and the corrosion resistance of the base material is improved while suppressing the deterioration of the conductivity and current collecting property of the separator. It is possible to make it.

If the conductive resin coating formed in this way is too thin, the effect of improving corrosion resistance cannot be sufficiently obtained, and if it is too thick, the electrical resistance (area resistance) of the separator increases, and the conductivity and current collection property decrease. ..
Therefore, the thickness of the conductive resin coating is preferably 1 μm or more and 30 μm or less.
In this case, it is possible to suppress deterioration of the conductivity and current collecting property of the separator while ensuring the corrosion resistance of the conductive resin film.

According to the present invention configured as described above, it is possible to improve the film forming speed and the manufacturing efficiency without making the film forming apparatus expensive.

The schematic diagram of the solid polymer electrolyte type fuel cell which concerns on this embodiment. The figure for demonstrating the manufacturing method of the separator for a fuel cell in this embodiment. The figure which shows typically the process of manufacturing the separator for a fuel cell in this embodiment. The schematic diagram of the separator for a fuel cell manufactured in this embodiment.

Hereinafter, an embodiment of the method for manufacturing a separator for a fuel cell according to the present invention will be described with reference to the drawings.

As shown in FIG. 1, the fuel cell separator manufacturing method of the present embodiment is a method for manufacturing a separator used in, for example, a solid polymer electrolyte fuel cell X. This solid polymer electrolyte type fuel cell X is used in, for example, a fuel cell vehicle, and is composed of cells x4 composed of a fuel electrode x1, an air electrode x2, and an electrolyte x3 sandwiched between them in a stacked manner. be. Further, a current collector member x5 is provided in the upper part and the lower part, and a separator Z is provided between the cell x4 and the cell x4.
Although the current collector member x5 is formed thicker than the separator Z, it has the same structure as the separator Z, and it goes without saying that it can be manufactured by the manufacturing method of the present embodiment.

Specifically, as shown in FIG. 2, in this separator manufacturing method, a gas barrier film forming process for forming a gas barrier film 2 on a substrate 1 and a substrate 1 on which the gas barrier film 2 is formed are pressed to form a groove 3. It includes a concave groove forming process for forming and a conductive resin film forming process for forming a conductive resin film 4 on the surface of the gas barrier film 2.

First, the base material 1 will be described.
The base material 1 is a sheet-like (flat plate-like) one in which the concave groove 3 is not formed, and in the present embodiment, an inexpensive aluminum base material 1 having high thermal conductivity is used. As shown in FIG. 3, the aluminum base material 1 is, for example, a sheet-shaped aluminum plate having a thickness of about 100 nm, and is wound into a coil after undergoing processes such as washing and drying, and is in the state of an aluminum coil AC. It is transported to the gas barrier film forming process.

[Gas barrier film forming process]
In the gas barrier film forming process, the gas barrier film 2 is formed on at least one surface of the aluminum base material 1. The gas barrier film 2 is a film that has conductivity and suppresses the permeation of oxygen and water vapor, and is a conductive carbon film here.

In this embodiment, as shown in FIG. 3, a so-called roll-to-roll type film forming apparatus 100 is used, and a diamond-like carbon film having conductivity as a gas barrier film 2 is formed on the front surface and the back surface of the aluminum base material 1, respectively. 2 (hereinafter referred to as conductive DLC film 2) is formed. An amorphous carbon film (conductive a-C film) may be formed as the gas barrier film 2 instead of the conductive DLC film 2.

The film forming apparatus 100 includes a delivery roller 10 that sends out the aluminum base material 1 in a sheet shape from the set aluminum coil AC, and a take-up roller 20 that winds up the sent out sheet-shaped aluminum base material 1 in a coil shape. It is provided with a vacuum chamber 30 for accommodating these rollers 10 and 20.

As shown in FIG. 3, in the vacuum chamber 30, a first roller accommodating chamber 31 for accommodating the delivery roller 10 is formed on one end side in the transport direction of the aluminum base material 1, and the take-up roller 20 is formed on the other end side in the transport direction. The second roller accommodating chamber 32 for accommodating the above is formed. For example, 1 Pa of nitrogen gas is introduced into the first roller accommodating chamber 31 and the second roller accommodating chamber 32.

The vacuum chamber 30 includes a cleaning chamber 33 for cleaning the aluminum substrate 1, an ion implantation chamber 34 for implanting film-implanted ions into the aluminum substrate 1, a film-forming chamber 35 for forming a conductive DLC film on the aluminum substrate 1, and the like. Each process is divided into multiple rooms.
A transfer roller, for example, a pressure welding roller is provided in the partition of each room, and the pressure welding roller presses the aluminum base material 1 so that different types of gas do not flow between the rooms. There is.

The cleaning room 33 is a room in which, for example, 1 Pa of argon gas is introduced and the oxide film (Al ₂ O ₃ ) of the aluminum base material 1 is removed by argon gas cleaning. The cleaning chamber 33 is provided with a pair of inductively coupled high frequency antennas 41.

The ion implantation chamber 34 is a room into which, for example, 1 Pa of nitrogen gas is introduced to form a nucleus (AlN) on the aluminum substrate 1. This nucleus is like a hair root in hair, and by forming a conductive DLC film described later on this nucleus, the adhesion of the conductive DLC film is improved. The ion implantation chamber 34 is provided with a pair of inductively coupled high frequency antennas 42.

The film forming chamber 35 is a chamber in which, for example, 1 Pa of a raw material gas is introduced to form a conductive DLC film on the aluminum base material 1. The film forming chamber 35 is provided with a pair of heaters 50 and a pair of inductively coupled high frequency antennas 43, and these heaters 50 and the inductively coupled high frequency antenna 43 are arranged so as to face each other.
Specifically, first, the aluminum base material 1 is held at 250 to 400 ° C. by a heater 50, and a mixed gas of, for example, methane and acetylene is introduced as a raw material gas. Then, by supplying high frequency power to the induction coupling type high frequency antenna 43, a discharge plasma containing carbon ions is generated in the vicinity of the surface of the aluminum base material 1, and a negative DC voltage or a negative pulse voltage is applied to the aluminum base material. By applying the voltage, as shown in FIG. 2A, the conductive DLC coating 2 is formed on the front surface and the back surface of the aluminum base material 1, respectively.

If the conductive DLC film 2 thus formed is too thin, a sufficient gas barrier effect cannot be obtained, and if it is too thick, the film forming time becomes long and it is disadvantageous in terms of productivity. Therefore, the film thickness is 10 nm or more. It is preferably 500 nm or less, and a more preferable range is 50 nm or more and 100 nm or less.

In the present embodiment, the film-formed base material 1'on which the conductive DLC film 2 is formed is wound again in a coil shape by the take-up roller 20 and conveyed to the groove forming process.

[Groove formation process]
In the groove forming process, for example, the film-formed base material 1'on which the gas barrier film 2 is formed is press-processed to form a concave groove 3 through which hydrogen and oxygen flow. The shape, number, arrangement, and the like of the concave grooves 3 can be variously changed, but here, as shown in FIG. 2B, the concave grooves 3 have a depth of about 1 mm and a width of about 1 mm, for example.
Specifically, as shown in FIG. 3, the concave groove 3 is formed by feeding the coil-shaped film-formed base material 1'again into a sheet shape and forming a desired concave groove 3 by, for example, bending. The sheet-shaped film-formed base material 1'is cut into a desired size. After cutting the film-formed base material 1'delivered into a sheet into a desired size, a desired concave groove 3 may be formed by bending or the like.

[Conductive resin film forming process]
Here, the above-mentioned conductive DLC coating 2 exhibits excellent corrosion resistance to acid and alkaline solutions and at the same time has excellent gas barrier properties, but on the other hand, many irregularities and pinholes existing on the surface of the base material 1 are present. It is difficult to completely cover such defective parts, and these defective parts are a major factor in the deterioration of corrosion resistance.
Therefore, in the conductive resin film forming process, the gas barrier film 2 formed on the base material 1 is covered with the conductive resin film 4, thereby substantially sealing the above-mentioned defective portion, thereby making the separator Z conductive. And, the corrosion resistance of the base material 1 is improved while suppressing the deterioration of the current collecting property. That is, the conductive resin coating 4 is chemically passivated by covering the gas barrier coating 2 including the defective portion, thereby improving the corrosion resistance.

The conductive resin coating 4 of the present embodiment is composed of a conductive filler such as graphite particles or conductive ceramic powder and a binder resin, and in the present embodiment, as shown in FIG. 2C, the surface side of the aluminum base material 1 is formed. It is applied onto the conductive DLC film 2 on both the back surface side and the back surface side.

Specifically, the conductive resin film 4 can be formed by coating the surface of the gas barrier film 2 with the conductive resin film 4 by, for example, a dipping method, a spray method, an electrodeposition method, a blade coating method, or the like. When a complicated groove is formed in the base material 1, there is an advantage that the electrodeposition method can easily form the conductive resin coating 4 having a uniform thickness.

If the conductive resin film 4 thus formed is too thin, sufficient corrosion resistance cannot be obtained, and if it is too thick, the contact resistance (area resistance) of the separator increases, and the conductivity and current collection property decrease. The film thickness is preferably 1 μm or more and 30 μm or less, and more preferably 3 μm or more and 20 μm or less.

According to the method for manufacturing the fuel cell separator Z according to the present embodiment configured as described above, the conductive DLC film 2 is formed on the aluminum base material 1 before the concave groove 3 is formed, so that the film forming apparatus 100 Inside, the sheet-shaped aluminum base material 1 can be sent out or wound up by a feeding roller 10 or a winding roller 20. As a result, since the roll-to-roll type film forming apparatus 100 can be used instead of the cassette-to-cassette type, the film forming speed can be improved and the manufacturing efficiency can be improved by continuously manufacturing the separator Z.

Further, since the sheet-shaped aluminum base material 1 is conveyed in the film forming apparatus 100, it is sufficient that a small gap is formed in the partition of each room partitioned for each process so that the sheet can pass through. As a result, by providing a pressure welding roller in the partition of each room to convey the sheet-shaped base material, it is possible to prevent different types of gas from coming and going between the rooms without installing an expensive gate valve. The device can be inexpensive.

In addition, as shown in FIG. 4, where corrosion resistance is important in the concave groove 3 (region shown in S1 of FIG. 4) through which hydrogen and oxygen pass, corrosion resistance is ensured by the conductive resin coating 4. In the region where the contact resistance with the adjacent cells x4 is important (the region shown in S2 of FIG. 4), the reduction of the contact resistance due to corrosion due to the gas barrier effect due to the conductive DLC coating can be suppressed.

The present invention is not limited to the above embodiment.

For example, the base material 1 is not limited to an aluminum base material, and has at least one kind of metal among nickel (Ni), iron (Fe), magnesium (Mg), titanium (Ti), and alloys containing these metals. It may be a thing.

The gas barrier film 2 is not limited to the one described in the above embodiment, and may be, for example, a metal carbide film, a metal oxycarbide film, a metal nitride film, a metal bolide film, a metal silicide film, or the like.

The conductive resin coating 4 is not limited to the one described in the above embodiment, and for example, even if the conductive resin coating is a carbon-based conductive resin coating containing carbon-based particles as a conductive substance in the resin binder, the conductive resin coating 4 is conductive in the resin binder. As the material, a conductive ceramic powder such as metal carbide or metal nitride, or a metal-based conductive resin coating containing metal particles or metal compound particles may be used. Further, the type of the resin binder is not particularly limited, and a phenol resin, an epoxy resin, an acrylic resin or a fluororesin having high heat resistance can be preferably used.

The formation of the gas barrier film is not limited to that described in the above embodiment, and for example, a plasma CVD method, a vacuum vapor deposition method, a sputtering method, an ion plating method, or the like may be used.

In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

X ・ ・ ・ Separator 1 ・ ・ ・ Base material 2 ・ ・ ・ Gas barrier film (conductive DLC film)
3 ・ ・ ・ Recessed groove 4 ・ ・ ・ Conductive resin coating 100 ・ ・ ・ Film forming device 10 ・ ・ ・ Delivery roller 20 ・ ・ ・ Winding roller 30 ・ ・ ・ Vacuum chamber

Claims (5)

The process of transferring the sheet-shaped substrate from the ion implantation chamber, which partitions the vacuum chamber, to the film formation chamber while winding it while feeding it with a transfer roller.
An ion implantation process in which ions are implanted into at least one surface of the substrate in the ion implantation chamber to form nuclei in the substrate.
In the deposition chamber, together with generating a discharge plasma, by applying a negative DC voltage or a negative pulse voltage to the substrate, the at least one surface of the substrate, gas barrier film in close contact with the core And the gas barrier film formation process to form
A method for manufacturing a separator for a fuel cell, comprising a recessed groove forming process for forming a recessed groove in the substrate after the gas barrier film forming process. The first aspect of the present invention, wherein the base material has at least one kind of metal among aluminum (Al), titanium (Ti), iron (Fe), magnesium (Mg), nickel (Ni) or an alloy containing these metals. How to manufacture a separator for a fuel cell. The method for manufacturing a fuel cell separator according to claim 1 or 2, wherein the thickness of the gas barrier coating is 10 nm or more and 500 nm or less. The method for manufacturing a fuel cell separator according to any one of claims 1 to 3, further comprising a conductive resin film forming process for forming a conductive resin film on the surface of the gas barrier film. The method for manufacturing a fuel cell separator according to claim 4, wherein the thickness of the conductive resin coating is 1 μm or more and 30 μm or less.

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