JP5369492B2 - Separator for fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to a separator for a fuel cell, and in particular, a separator used for each unit cell of a fuel cell in which a plurality of unit cells each having an electrode disposed on both sides of a solid polymer electrolyte membrane are connected, and a method for producing such a separator. About.

A fuel cell is simply a device that continuously supplies fuel (reducing agent) and oxygen or air (oxidant) from the outside, and reacts electrochemically to extract electrical energy. It is classified by type, use, etc. Recently, solid oxide fuel cells, molten carbonate fuel cells, phosphoric acid fuel cells, solid polymer electrolyte fuel cells, and alkaline aqueous fuel cells are mainly used depending on the type of electrolyte used. Generally, it is classified into five types.
These fuel cells use hydrogen gas generated from methane or the like as a fuel. Recently, a direct methanol fuel cell (hereinafter also referred to as DMFC) that directly uses an aqueous methanol solution as a fuel is also known. Yes.
In such a fuel cell, a polymer electrolyte fuel cell having a structure in which a solid polymer membrane is sandwiched between two types of catalyst and these members are sandwiched between a gas diffusion layer (GDL) and a separator. (Hereinafter also referred to as PEFC) is attracting attention.

In this PEFC, a unit structure in which an air electrode (oxygen electrode) and a fuel electrode (hydrogen electrode) are arranged on both sides of a solid polymer electrolyte membrane is stacked in order to obtain a desired electromotive force, Alternatively, a structure in which a plurality of planes are connected in series is employed. For example, in the case of the above-described stack structure, the separator disposed between the unit cells is formed with a fuel gas supply groove for supplying fuel gas to the adjacent unit cell on its side. An oxidant gas supply groove for supplying oxidant gas to the other adjacent unit cell is formed on the other surface.
As such a separator, a metal separator is preferable from the viewpoint of cost and strength, but there is a problem in corrosion resistance. For this reason, metal separators that have been provided with corrosion resistance by forming a conductive electrodeposition coating have been developed (Patent Documents 1, 2, and 3).
JP 2004-31166 A JP 2003-249240 A JP 2004-197225 A

However, in the case of the metal separator in which the electrodeposition coating film as described above is directly formed on the metal base material, when a base material such as aluminum that easily generates an oxide film is used as the metal base material, the step of removing the oxide film There has been a problem that the oxide film is regenerated during cleaning or after transporting or during transportation, and the connection resistance between the metal substrate and the electrodeposition coating film is increased. Furthermore, when an electrodeposition coating is directly formed on aluminum, defects such as unevenness, chipping and pinholes are likely to occur in the electrodeposition coating, and it is difficult to form a uniform electrodeposition coating. If there is a pinhole, there is a problem that aluminum is rapidly corroded during the electrodeposition process.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a separator for a fuel cell that is excellent in strength and corrosion resistance and has low connection resistance, and a method for manufacturing the same.

In order to achieve such an object, the separator of the present invention is formed by electrodeposition so as to cover the metal substrate through the metal substrate and the first intermediate layer, the third intermediate layer, and the second intermediate layer. A conductive resin layer, wherein the metal substrate is aluminum or an aluminum alloy, the first intermediate layer is a nickel plating layer or a copper plating layer, and the second intermediate layer is a tin plating layer or a tin alloy plating The third intermediate layer is interposed between the first intermediate layer and the second intermediate layer, is a copper plating layer or a nickel plating layer, and is made of a metal different from the first intermediate layer. The resin layer is configured to contain a conductive material.

As another aspect of the present invention, the metal substrate is configured to have a groove on at least one surface.
As another aspect of the present invention, the metal substrate is configured to have a plurality of through holes.
As another aspect of the present invention, the conductive material is configured to be at least one of carbon particles, carbon nanotubes, carbon nanofibers, carbon nanohorns, and corrosion-resistant metals.
As another aspect of the present invention, the tin alloy plating layer is a tin alloy plating layer of any one of tin-nickel, tin-copper, tin-cobalt, tin-silver, tin-zinc, tin-gold, and tin-bismuth. It was set as such a structure.
As another aspect of the present invention, the tin alloy plating layer is made of tin-nickel and has a thickness in the range of 0.3 to 2 μm.

In the method for producing a fuel cell separator of the present invention, a metal substrate made of aluminum or an aluminum alloy is subjected to a zincate treatment, and then a first intermediate layer made of a nickel plating layer or a copper plating layer is formed on the metal substrate. A second intermediate layer made of a copper plating layer or a nickel plating layer and made of a metal different from the first intermediate layer is formed on the first intermediate layer, and is made of a tin plating layer or a tin alloy plating layer. An intermediate layer is formed on the third intermediate layer , and then the resin layer is formed on the second intermediate layer by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in a resin having electrodeposition properties. It was set as the structure which forms.

The separator of the present invention comprises a first intermediate layer comprising a nickel plating layer or a copper plating layer and a tin plating layer or a tin alloy plating layer between a metal substrate comprising aluminum or an aluminum alloy and a conductive resin layer. Since the two intermediate layers are interposed, the connection resistance between the metal substrate and the resin layer is small, the power generation capability of the fuel cell can be improved, and high strength and excellent corrosion resistance are provided. Moreover, when the tin alloy plating layer is made of tin-nickel and the thickness is in the range of 0.3 to 2 μm, the separator of the present invention has good bending workability. Furthermore, when the third intermediate layer is provided, the corrosion resistance is further improved, and the power generation capacity and durability of the fuel cell are further improved.
In the separator manufacturing method of the present invention, the first intermediate layer and the second intermediate layer are formed on the metal substrate before the conductive resin layer is formed on the metal substrate by electrodeposition. Corrosion of the metal substrate is prevented, and a uniform resin layer is formed, whereby the connection resistance between the metal substrate and the resin layer is small and the adhesion strength is high. In addition, when the third intermediate layer is formed between the first intermediate layer and the second intermediate layer, the adhesion between the first intermediate layer and the second intermediate layer is further improved, and a more durable separator is manufactured. Is possible.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Separator]
FIG. 1 is a partial cross-sectional view showing an embodiment of a separator for a fuel cell of the present invention. In FIG. 1, a separator 1 according to the present invention includes a metal substrate 2, a groove 3 formed on both surfaces of the metal substrate 2, and a first intermediate layer 4 and a second intermediate layer so as to cover both surfaces of the metal substrate 2. 5 and a resin layer 6 formed by electrodeposition, and the resin layer 6 contains a conductive material.
When the separator 1 is incorporated in a fuel cell, one of the groove portions 3 of the metal substrate 2 serves as a fuel gas supply groove portion for supplying fuel gas to an adjacent unit cell, and the other is adjacent to another adjacent groove. This is an oxidant gas supply groove for supplying an oxidant gas to the unit cell. Further, one of the groove portions 3 may be either a fuel gas supply groove portion or an oxidant gas supply groove portion, and the other may be a cooling water groove. Further, the groove 3 may be provided only on one surface of the metal base 2. The shape of the groove 3 is not particularly limited, and may be a meandering continuous shape, a comb shape, or the like, and the depth, width, and cross-sectional shape are not particularly limited. Further, the shape of the groove 3 may be different between the front and back of the metal base 2.

FIG. 2 is a partial cross-sectional view showing another embodiment of the separator for a fuel cell of the present invention. In FIG. 2, the separator 11 of the present invention covers both surfaces of a metal substrate 12, a plurality of through holes 13 formed in the metal substrate 12, and the metal substrate 12 including the inner wall surfaces of these through holes 13. And a resin layer 16 formed by electrodeposition via the first intermediate layer 14 and the second intermediate layer 15, and the resin layer 16 contains a conductive material.
The through-hole 13 of the metal substrate 12 serves as a flow path for supplying fuel gas or oxidant gas to the unit cell when the separator 11 is incorporated in the fuel cell. There is no restriction | limiting in particular in the magnitude | size, the number of such a through-hole 13, and arrangement | positioning density.

The metal bases 2 and 12 constituting the separators 1 and 11 of the present invention are pure aluminum (1000 series) and aluminum alloy. Examples of the aluminum alloy include 2000 series, 5000 series, 6000 series, and 7000 series of aluminum.
The first intermediate layers 4 and 14 constituting the separators 1 and 11 serve to reduce the connection resistance between the metal bases 2 and 12 and the second intermediate layers 5 and 15 and the resin layers 6 and 16, and the metal bases 2 and 12 serves to prevent the formation of an oxide film. Such 1st intermediate | middle layers 4 and 14 can be made into a nickel plating layer or a copper plating layer, and thickness can be suitably set in the range of about 0.1-10 micrometers, for example. When the thickness of the first intermediate layers 4 and 14 is less than 0.1 μm, the above-described effects are not sufficiently expressed, while when the thickness exceeds 10 μm, the flatness and workability are reduced. The manufacturing cost is increased, which is not preferable.
The second intermediate layers 5 and 15 constituting the separators 1 and 11 improve the adhesion between the metal bases 2 and 12 and the resin layers 6 and 16 and improve the strength and durability of the separator. It is. Such second intermediate layers 5 and 15 can be tin plating layers or tin alloy plating layers, and as the tin alloy plating layer, tin-nickel, tin-copper, tin-cobalt, tin-silver, tin -It is preferable to use a tin alloy plating layer of zinc, tin-gold, or tin-bismuth. The thickness of the 2nd intermediate | middle layers 5 and 15 can be suitably set, for example in the range of about 0.3-5 micrometers. When the thickness of the second intermediate layers 5 and 15 is less than 0.3 μm, the above-described effects are not sufficiently expressed. On the other hand, when the thickness exceeds 5 μm, the flatness and workability are reduced. It is not preferable because cracks are easily generated. In particular, when the second intermediate layers 5 and 15 are tin-nickel tin alloy plating layers, it is possible to impart good folding processability to the separators 1 and 11 by setting the thickness in the range of 0.3 to 2 μm. it can.

The resin layers 6 and 16 constituting the separators 1 and 11 are conductive and provide corrosion resistance to the metal bases 2 and 12. The resin layers 6 and 16 are formed by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in various anionic or cationic synthetic polymer resins having electrodeposition properties, and then cured. Can be formed.
Examples of the anionic synthetic polymer resin include acrylic resin, polyester resin, maleated oil resin, polybutadiene resin, epoxy resin, polyamide resin, polyimide resin, etc., and these can be used alone or as a mixture of any combination. Can be used. Moreover, you may use together said crosslinking | crosslinked resin, such as anionic synthetic polymer resin and a melamine resin, a phenol resin, and a urethane resin. On the other hand, examples of the cationic synthetic polymer resin include acrylic resin, epoxy resin, urethane resin, polybutadiene resin, polyamide resin, polyimide resin, and the like. These can be used alone or as a mixture of any combination. Can do. Moreover, you may use together said cationic synthetic polymer resin and crosslinkable resin, such as a polyester resin and a urethane resin.
Further, in order to impart tackiness to the above-described synthetic polymer resin having electrodeposition properties, a tackifier resin such as rosin, terpene, and petroleum resin may be added as necessary.

Such an electrodepositable synthetic polymer resin is subjected to electrodeposition in a state where it is neutralized with an alkaline or acidic substance and solubilized in water, or in an aqueous dispersion state. That is, the anionic synthetic polymer resin is neutralized with amines such as trimethylamine, diethylamine, dimethylethanolamine and diisopropanolamine, and inorganic alkalis such as ammonia and caustic potash. The cationic synthetic polymer resin is neutralized with an acid such as formic acid, acetic acid, propionic acid, or lactic acid. The neutralized water-soluble polymer resin is used in a state of being diluted in water as a water-dispersed type or a dissolved type.
The thickness of the resin layers 6 and 16 formed by electrodeposition can be in the range of 0.1 to 100 μm, preferably 3 to 30 μm. If the thickness of the resin layers 6 and 16 is less than 0.1 μm, good corrosion resistance may not be ensured due to the occurrence of pinholes, etc. If the thickness exceeds 100 μm, the occurrence of cracks after drying and solidification and production This is not preferable because of problems such as deterioration in performance and high cost.

  Examples of the conductive material contained in the resin layers 6 and 16 include carbon materials such as carbon particles, carbon nanotubes, carbon nanofibers, and carbon nanohorns, and corrosion-resistant metals. If it is obtained, it is not limited to these conductive materials. In particular, fine fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and carbon nanohorns are suitable for imparting conductivity to the resin layers 6 and 16. The content of the conductive material in the resin layers 6 and 16 can be set as appropriate according to the conductivity required for the resin layers 6 and 16, and can be set in the range of 10 to 90% by weight, for example.

Fine fibrous carbon materials such as carbon nanotubes, carbon nanofibers, and carbon nanohorns are expected to be applied to various fields such as composite materials and electronic devices as nanotechnology materials. When used as a composite material, the physical properties of these can be imparted to the composite material. For example, carbon nanotubes are excellent in terms of electrical conductivity, acid resistance, workability, mechanical strength, etc. When used as a filler in a composite material, the carbon nanotube has excellent physical properties. Can be granted.
The above-described embodiments of the separator of the present invention are examples, and the present invention is not limited to these embodiments.

  For example, in the separators 1 and 11 described above, a third intermediate layer that is a copper plating layer or a nickel plating layer between the first intermediate layers 4 and 14 and the second intermediate layers 5 and 15, A layer made of a metal different from the layers 4 and 14 may be interposed. Therefore, a separator in which a nickel plating layer (first intermediate layer), a copper plating layer (third intermediate layer), a tin plating layer or a tin alloy plating layer (second intermediate layer) are laminated in this order on the metal substrate, or A separator in which a copper plating layer (first intermediate layer), a nickel plating layer (third intermediate layer), a tin plating layer or a tin alloy plating layer (second intermediate layer) is laminated in this order on a metal substrate. Can do. Thus, by interposing the third intermediate layer between the first intermediate layer and the second intermediate layer, the adhesion between the first intermediate layer and the second intermediate layer is improved, and the corrosion resistance of the separator is further improved. . Thereby, the power generation capability and durability of the fuel cell are further improved. The thickness of such a 3rd intermediate | middle layer can be suitably set, for example in the range of about 0.03-5 micrometers. When the thickness of the third intermediate layer is less than 0.03 μm, the above-described effect due to the provision of the third intermediate layer is not sufficiently exhibited, whereas when the thickness exceeds 5 μm, flatness and workability Is unfavorable because it also decreases the manufacturing cost.

[Manufacturing method of separator]
Next, the manufacturing method of the separator for fuel cells of this invention is demonstrated.
FIG. 3 is a process diagram for explaining the manufacturing method of the present invention using the separator 1 shown in FIG. 1 as an example. In the present invention, resists 7 and 7 are formed in a desired pattern on both sides of a metal plate 2 'made of aluminum or aluminum alloy by photolithography, and the metal plate 2' is etched from both sides using the resists 7 and 7 as a mask. Grooves 3 and 3 are formed (FIG. 3A). Thereafter, the resists 7 and 7 are removed to obtain the metal substrate 2 (FIG. 3B).
Next, a first intermediate layer 4 which is a nickel plating layer or a copper plating layer is formed on both surfaces of the metal substrate 2 (FIG. 3C). The first intermediate layer 4 is formed by first performing a zincate treatment on the metal substrate 2 and then performing electroless plating or electroplating. The first intermediate layer 4 formed in this way prevents the oxide film from being regenerated on the metal substrate 2, and the second intermediate layer 5 and the resin layer 6 formed in a later step and the metal substrate 2 Reduce connection resistance.

Next, a second intermediate layer 5 which is a tin plating layer or a tin alloy plating layer is formed on the first intermediate layer 4 (FIG. 3D). The second intermediate layer 5 can be formed by electroless plating or electroplating. The second intermediate layer 5 thus formed suppresses the occurrence of defects such as unevenness, chipping, and pinholes in the resin layer 6 that is electrodeposited in a later step, and the adhesion of the resin layer 6 To improve.
Next, a film is formed on the second intermediate layer 5 by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in various anionic or cationic synthetic polymer resins having electrodeposition properties. The resin layer 6 is formed by curing (FIG. 3E). The resin layer 6 formed in this way has good conductivity and high corrosion resistance. Thereby, the separator 1 of this invention is obtained.

FIG. 4 is a process diagram for explaining the separator manufacturing method of the present invention, taking the separator 11 shown in FIG. 2 as an example. In the present invention, resists 17 and 17 having a plurality of openings are formed by photolithography on both sides of a metal plate 12 'made of aluminum or an aluminum alloy, and the metal plate 12' is formed from both sides using the resists 17 and 17 as a mask. Etching is performed to form a plurality of through holes 13 (FIG. 4A). The plurality of openings of the resists 17 and 17 are positioned so as to face each other through the metal plate 12 '. Thereafter, the resists 17 and 17 are peeled off to obtain the metal substrate 12 (FIG. 4B).
The through-hole 13 can be formed by a sandblasting method, a laser processing method, a drilling method, or the like in addition to the above-described etching method.
Next, the first intermediate layer 14 which is a nickel plating layer or a copper plating layer is formed on the metal substrate 12 including the inner wall surface of the through hole 13 (FIG. 4C). The formation of the first intermediate layer 14 can be performed similarly to the formation of the first intermediate layer 4 in the above-described embodiment.

Next, the second intermediate layer 15 is formed so as to cover the first intermediate layer 14 (FIG. 4D). The formation of the second intermediate layer 15 can also be performed in the same manner as the formation of the second intermediate layer 5 in the above-described embodiment.
Next, a film is formed on the second intermediate layer 15 by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in various anionic or cationic synthetic polymer resins having electrodeposition properties. The resin layer 16 is formed by curing (FIG. 4E). Thereby, the separator 11 is obtained.
The above-described embodiments of the separator manufacturing method are examples, and the present invention is not limited to these embodiments.

  For example, as described above, a third intermediate layer that is a copper plating layer or a nickel plating layer between the first intermediate layers 4 and 14 and the second intermediate layers 5 and 15, In the case of interposing a layer made of a metal different from 14, after forming the first intermediate layer 4, 14, a third intermediate layer made of a copper plating layer or a nickel plating layer is formed on the first intermediate layer 4, 14. Then, the second intermediate layers 5 and 15 are formed on the third intermediate layer. The third intermediate layer can be formed by electroless plating or electroplating, and this third intermediate layer improves the adhesion between the first intermediate layers 4 and 14 and the second intermediate layers 5 and 15. .

[Example of fuel cell using separator of the present invention]
Here, an example of a polymer electrolyte fuel cell using the separator of the present invention will be described with reference to FIGS. FIG. 5 is a partial configuration diagram for explaining the structure of the polymer electrolyte fuel cell, and FIG. 6 is a diagram for explaining the membrane electrode assembly constituting the polymer electrolyte fuel cell. FIG. 7 and FIG. 8 are perspective views showing the state in which the separator of the polymer electrolyte fuel cell and the membrane electrode assembly are separated from different directions.
5 to 8, the polymer electrolyte fuel cell 21 has a stack structure in which a plurality of unit cells each including a membrane-electrode assembly (MEA) 31 and a separator 41 are stacked. .

As shown in FIG. 6, the MEA 31 includes a fuel electrode (hydrogen electrode) 35 including a catalyst layer 33 and a gas diffusion layer (GDL) 34 disposed on one surface of the polymer electrolyte membrane 32. And an air electrode (oxygen electrode) 38 composed of a catalyst layer 36 and a gas diffusion layer (GDL) 37 disposed on the other surface of the polymer electrolyte membrane 32.
The separator 41 has a fuel gas supply groove 43a on one surface, a separator 41A having an oxidant gas supply groove 44a on the other surface, a fuel gas supply groove 43a on one surface, and the other surface. The separator 41B has a cooling water groove 44b on the surface, and the separator 41C has a cooling water groove 43b on one surface and an oxidant gas supply groove 44a on the other surface. Such separators 41A, 41B, and 41C are separators of the present invention, and a resin layer is formed on both surfaces via a first intermediate layer and a second intermediate layer as shown in FIG. It is omitted in the illustrated example.

  Two fuel gas supply holes 45a and 45b, two oxidant gas supply holes 46a and 46b, and two cooling water supplies are provided at predetermined positions of the separators 41A, 41B and 41C and the polymer electrolyte membrane 32. Holes 47a and 47b are formed as through holes. Then, the air electrode (oxygen electrode) 38 of the MEA 31 is in contact with the surface of the separator 41A where the oxidizing gas supply groove 44a is formed, and the surface of the separator 41B where the fuel gas supply groove 43a is formed, The fuel electrode (hydrogen electrode) 35 of the MEA 31 abuts, and the surface of the separator 41B on which the cooling water groove 44b is formed and the surface of the separator 41C on which the cooling water groove 43b is formed abut. The separators 41A, 41B, and 41C and the MEA 31 that is a unit cell are stacked, and the polymer electrolyte fuel cell 21 is configured by repeating this process. In the stacked state, the two fuel gas supply holes 45a and 45b form fuel gas supply passages penetrating in the stacking direction, and the two oxidant gas supply holes 46a and 46b are respectively formed. An oxidant gas supply path that penetrates the laminating method is formed, and the two cooling water supply holes 47a and 47b each form a cooling water supply path that penetrates in the laminating direction.

  Another example of the polymer electrolyte fuel cell using the separator of the present invention will be described with reference to FIGS. FIG. 9 is a plan view for explaining the structure of the polymer electrolyte fuel cell, and FIG. 10 is a longitudinal sectional view taken along line AA of the polymer electrolyte fuel cell shown in FIG. Moreover, FIG. 11 is a figure for demonstrating the membrane electrode assembly which comprises a polymer electrolyte type fuel cell.

  As shown in FIGS. 9 and 10, the polymer electrolyte fuel cell 51 includes a plurality of unit cells 52 each including a membrane electrode assembly (MEA) 61 and separators 71A and 71B in a planar shape. This is a polymer electrolyte fuel cell that is arranged and electrically connected in series to extract voltages corresponding to the number of unit cells (four in FIG. 9). Further, around each unit cell 52, an insulating portion 55 having substantially the same thickness as this is provided, and the whole is flat. That is, the unit cell 52 and the insulating part 55 are provided in a planar shape by fitting the unit cell 52 into the cut-out part of the flat insulating part 55.

The polymer electrolyte fuel cell 51 is provided with a front and back connection part 57c for penetrating through the insulating part 55 located between adjacent unit cells of the insulating part 55 and connecting the front and back thereof. Then, the front / back connection portion 57c is connected to the separator 71A (for example, the fuel electrode side separator) of one adjacent unit cell via the connection wiring 57a, and the other adjacent one is connected via the connection wiring 57b. The unit cell is connected to a separator 71B (for example, an air electrode side separator). Thereby, adjacent unit cells are electrically connected in series. Wirings 75 and 76 are connected to the separator 71A of the unit cell 52 located at one end connected in series and the separator 71B of the unit cell 52 located at the other end.
In the illustrated example, the number of unit cells is four, but the number of unit cells is not limited.

The insulating part 55 insulates adjacent unit cells from each other except that they are connected by connection parts 57 (connection wirings 57a and 57b and front and back connection parts 57c). The material of the insulating part 55 is not particularly limited as long as it is excellent in terms of processability and durability. For example, glass epoxy, polyimide resin, or the like is used. The insulating portion 55 may be made of only an insulating material or may include a part of a conductive material.
As the front and back connection part 57c of the connection part 57, either a through-hole connection part or a filling via connection part or a bump connection part is provided in the insulating part 55 located between adjacent unit cells. it can. These front and back connection portions 57c can be formed as an application of conventional wiring board technology.

In addition, as shown in FIG. 11, the MEA 61 includes a fuel electrode (hydrogen electrode) composed of a catalyst layer 63 and a gas diffusion layer (GDL) 64 disposed on one surface of the polymer electrolyte membrane 62. ) 65, and an air electrode (oxygen electrode) 68 including a catalyst layer 66 and a gas diffusion layer (GDL) 67 disposed on the other surface of the polymer electrolyte membrane 62.
The separators 71A and 71B are separators according to the present invention as shown in FIG. 2, and have a conductive resin layer through a first intermediate layer and a second intermediate layer on a metal substrate having a plurality of through holes. It is.

Next, the present invention will be described in more detail by showing specific examples.
[ Reference Example 1]
An aluminum alloy (A5052P) having a size of 80 mm × 80 mm and a thickness of 0.8 mm was prepared as a metal plate material, and the surface was degreased.
Next, a dry film resist (manufactured by Nichigo Morton Co., Ltd.) is laminated on both surfaces of the aluminum alloy to form a 35 μm-thick photosensitive resist layer, and then exposed through a photomask for forming a groove ( A resist was formed by irradiating with a 5 kW mercury lamp for 15 seconds) and developing (spraying a 2% aqueous sodium hydrogen carbonate solution at 30 ° C.).

Next, a ferric chloride aqueous solution heated to 45 ° C. was sprayed from both sides of the aluminum alloy through the resist, and half-etched to a predetermined depth. Thereafter, the resist was peeled off with a 5% aqueous sodium hydrogen carbonate solution at 50 ° C. and subjected to a cleaning treatment. As a result, a metal substrate having a substantially semicircular cross section having a width of 1 mm and a depth of 0.3 mm, and a groove portion having a length of 1300 mm meandering with a deflection width of 50 mm and a pitch of 2 mm was obtained.
Next, pretreatment is performed on the above metal substrate using an aqueous nitric acid solution, and then zinc replacement treatment is performed under the following conditions to form a zinc alloy layer (thickness 0.05 μm), including the groove portion. Formed on top.
(Conditions for zinc replacement treatment)
・ Use bath: Zincate bath (Mertex Co., Ltd. ALMON EN)
・ Liquid temperature: 30 ℃
・ Processing time: 20 seconds

Next, a nickel plating layer (thickness 1 μm) was formed on the zinc alloy layer under the following electroplating conditions to form a first intermediate layer.
(Electroplating conditions)
-Bath used: Nickel chloride bath (AZ111 manufactured by Shipley Co., Ltd.)
・ PH: 2-5
・ Current density: 10 A / dm ²
・ Liquid temperature: 40 ℃

Next, a tin-nickel alloy plating layer (thickness 1 μm) was formed on the first intermediate layer under the following electroplating conditions to form a second intermediate layer.
(Electroplating conditions)
・ Use bath: Tin-nickel bath (EBALOY SNI manufactured by Sugawara Eugene Corporation)
・ PH: 2
・ Current density: 0.3 A / dm ²
・ Liquid temperature: 55 ℃

  Subsequently, carbon black (Vulcan XC-72 manufactured by Cabot Co., Ltd.) as a conductive material was added to and dispersed in the epoxy electrodeposition liquid by 75% by weight with respect to the resin solid content to obtain an electrodeposition liquid. The electrodeposition liquid was stirred at 20 ° C., and the metal substrate was immersed in the electrodeposition solution, electrodeposition was performed at a gap of 40 mm and a voltage of 50 V for 1 minute, and the pulled metal substrate was washed with pure water. Then, it dried with hot air (150 degreeC, 3 minutes) with the dryer, and also heat-hardened at 180 degreeC for 1 hour in nitrogen atmosphere. Thereby, a resin layer having a thickness of 15 μm was formed on the second intermediate layer, and a separator was obtained.

The epoxy electrodeposition solution used was prepared as follows.
First, 1000 parts by weight of diglycidyl ether of bisphenol A (epoxy equivalent 910) was dissolved in 463 parts by weight of ethylene glycol monoethyl ether while maintaining the temperature at 70 ° C. with stirring, and further 80.3 parts by weight of diethylamine was added to 100 parts. An amine epoxy adduct (A) was prepared by reacting at 2 ° C. for 2 hours.
Coronate L (manufactured by Nippon Polyurethane Co., Ltd. diisocyanate: NCO 13% non-volatile content 75% by weight) 875 parts by weight dibutyltin laurate 0.05 parts by weight and heated to 50 ° C. After that, the mixture was reacted at 120 ° C. for 90 minutes. A component (B) obtained by diluting the obtained reaction product with 130 parts by weight of ethylene glycol monoethyl ether was obtained.
Next, the mixture consisting of 1000 parts by weight of the above-described amine epoxy adduct (A) and 400 parts by weight of component (B) is neutralized with 30 parts by weight of glacial acetic acid, and then diluted with 570 parts by weight of deionized water. A resin A having a nonvolatile content of 50% by weight was prepared. An epoxy electrodeposition solution was prepared by blending 200.2 parts by weight of this resin A (resin component 86.3 volumes), 583.3 parts by weight of deionized water, and 2.4 parts by weight of dibutyltin laurate.

The presence or absence of pinholes in the resin layer of the produced separator was observed under the following conditions. As a result, it was confirmed that there was no pinhole.
(Pinhole observation conditions)
In 80 ° C, 1 molar sulfuric acid aqueous solution, the electric potential is scanned in the noble direction in the range of -2V to + 2V VS.NHE, and the current response is investigated. If the current response is 1μA / cm ² or less, there is no pinhole. to decide.

Moreover, as a result of measuring the electrical resistance of front and back conduction in the produced separator by the following method, it was 3.5 mΩ, and it was confirmed that the electrical resistance was low.
(Measurement method of electrical resistance)
Separator gas diffusion layer (TGP-H-060 190μm thickness manufactured by Toray Industries, Inc.)
Between the two electrodes, and further sandwiched between 5 mm thick copper-plated copper electrodes (pressure: 20 kgf / cm ² ) to measure the resistance between the electrodes.

[ Reference Example 2]
A separator was produced in the same manner as in Reference Example 1 except that a tin plating layer (thickness 1 μm) was formed as the second intermediate layer under the following electroplating conditions.
(Electroplating conditions)
・ Use bath: Sulfonate bath (Meltex Co., Ltd. Soldalon ST-200)
・ PH: 4.5-6.0
・ Current density: 1 A / dm ²
・ Liquid temperature: 40 ℃
As a result of observing the presence or absence of pinholes in the resin layer of the produced separator under the same conditions as in Reference Example 1, it was confirmed that no pinholes were present.
Further, the electrical resistance of front-back conduction in this separator was measured by the same method as in Reference Example 1. As a result, it was 4.6 mΩ, and it was confirmed that the electrical resistance was low.

[ Reference Example 3]
A separator was produced in the same manner as in Reference Example 1 except that a tin-cobalt plating layer (thickness 1 μm) was formed as the second intermediate layer under the following electroplating conditions.
(Electroplating conditions)
-Bath used: stannous sulfate bath (Pyroeye SC process, manufactured by Nippon Chemical Industry Co., Ltd.)
・ PH: 1-2
・ Current density: 0.5 A / dm ²
・ Liquid temperature: 40 ℃
As a result of observing the presence or absence of pinholes in the resin layer of the produced separator under the same conditions as in Reference Example 1, it was confirmed that no pinholes were present.
Moreover, the electrical resistance of the front and back conduction in this separator was measured by the same method as in Reference Example 1. As a result, it was 3.1 mΩ, and it was confirmed that the electrical resistance was low.

[ Reference Example 4]
A separator was produced in the same manner as in Reference Example 1 except that a copper plating layer (thickness: 1 μm) was formed as the first intermediate layer under the following electroless copper plating conditions.
(Electroless copper plating conditions)
・ Use bath: Electroless copper plating bath (Melplate CV-5100 manufactured by Meltex Co., Ltd.)
・ Liquid temperature: 50 ℃
-Plating time: 900 seconds As a result of observing the presence or absence of pinholes in the resin layer of the produced separator under the same conditions as in Reference Example 1, it was confirmed that no pinholes were present.
Moreover, the electrical resistance of the front and back conduction in this separator was measured by the same method as in Reference Example 1. As a result, it was 2.8 mΩ, and it was confirmed that the electrical resistance was low.

[Comparative Example 1]
A separator was produced in the same manner as in Reference Example 1 except that the second intermediate layer was not formed and only the nickel plating layer (first intermediate layer in Reference Example 1) was used as the intermediate layer.
As a result of observing the presence or absence of pinholes in the resin layer of the manufactured separator under the same conditions as in Reference Example 1, it was confirmed that pinholes were present and that the metal substrate was partially corroded.

[Comparative Example 2]
In the same manner as in Reference Example 1, except that the first intermediate layer and the second intermediate layer were not formed, and instead a nickel-copper plating layer (thickness 3 μm) was formed as an intermediate layer under the following electroplating conditions. Produced.
(Electroplating conditions)
-Bath used: Copper sulfate bath (Copper sulfate manufactured by Nippon Chemical Industry Co., Ltd.)
・ PH: 2
・ Current density: 0.3 A / dm ²
・ Liquid temperature: 50 ℃
As a result of observing the presence or absence of pinholes in the resin layer of the manufactured separator under the same conditions as in Reference Example 1, it was confirmed that pinholes were present and that the metal substrate was partially corroded.

[Example 1 ]
A copper plating layer (thickness 0.5 μm) is formed on the first intermediate layer (nickel plating layer) under the following electroplating conditions to form a third intermediate layer, and the second intermediate layer (tin) is formed on the third intermediate layer. A separator was prepared in the same manner as in Reference Example 1 except that a nickel alloy plating layer was formed.
(Electroplating conditions)
-Bath used: Copper sulfate bath (Copper sulfate manufactured by Nippon Chemical Industry Co., Ltd.)
・ PH: 2
・ Current density: 0.3 A / dm ²
・ Liquid temperature: 50 ℃
A fuel cell was produced as described below using the separator produced in this manner, the IV characteristics were evaluated, and the output was measured. The result was 0.61 W.

On the other hand, a fuel cell was similarly produced using the separator produced in Reference Example 1 described above, and the output was measured. As a result, it was 0.38 W.
From this result, it was confirmed that the power generation capability of the fuel cell was further improved by interposing the third intermediate layer between the first intermediate layer and the second intermediate layer.
(Evaluation of IV characteristics)
Using the produced separator, the following membrane electrode assembly (MEA), and a fuel cell, a single-cell fuel cell was produced, and the IV characteristics were evaluated under the following experimental conditions.
(Materials used)
MEA: anode catalyst = Pt / C 50% by weight (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.)
Pt loading = 0.3 mg / cm ²
Cathode catalyst = Pt / C 50% by weight (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.)
Pt loading = 0.3 mg / cm ²
Electrolyte = Nafion112 (manufactured by DuPont)
Electrode area = 25 cm ²
-Fuel cell: JARI (Japan Automobile Research Institute) standard cell (experimental conditions)
・ Anode gas: Pure hydrogen (utilization rate 70%, dew point 80 ° C)
Cathode gas: Air (utilization rate 40%, dew point 70 ° C)
-Cell temperature: 80 ° C
・ Current density: 0 to 1 A / cm ²

[Example 2 ]
A nickel plating layer (thickness 0.5 μm) is formed on the first intermediate layer (copper plating layer) under the following electroplating conditions to form a third intermediate layer, and the second intermediate layer (tin) is formed on the third intermediate layer. A separator was prepared in the same manner as in Reference Example 4 except that a nickel alloy plating layer was formed.
(Electroplating conditions)
-Bath used: Nickel chloride bath (AZ111 manufactured by Shipley Co., Ltd.)
・ PH: 2-5
・ Current density: 10 A / dm ²
・ Liquid temperature: 40 ℃
Using the separator thus produced, a fuel cell was produced in the same manner as in Example 1 and the output was measured. As a result, it was 0.61 W.
On the other hand, as a result of producing a fuel cell in the same manner using the separator produced in Reference Example 4 and measuring the output, it was 0.44 W.
From this result, it was confirmed that the power generation capability of the fuel cell was further improved by interposing the third intermediate layer between the first intermediate layer and the second intermediate layer.

[ Reference Example 5 ]
A separator was produced in the same manner as in Reference Example 1 except that the electroplating conditions were changed as follows and the thickness of the second intermediate layer (tin-nickel alloy plating layer) was 2 μm.
(Electroplating conditions)
・ Use bath: Tin-nickel bath (EBALOY SNI manufactured by Sugawara Eugene Corporation)
・ PH: 2
・ Current density: 0.3 A / dm ²
・ Liquid temperature: 55 ℃
The folding separator suitability of the produced separator was evaluated by the following method. As a result, it was confirmed that the first intermediate layer and the second intermediate layer could be folded without causing cracks and had good bending workability.

Moreover, about the separator produced in the above-mentioned reference example 1, as a result of evaluating the bending workability similarly, it was confirmed that it has favorable bending workability.
(Evaluation method for bending workability)
The separator is bent 90 ° so that the radius of the bent portion is 0.1 mm, and the presence or absence of cracks in the first intermediate layer and the second intermediate layer is confirmed using an optical microscope.

[ Reference Example 6 ]
A separator was produced in the same manner as in Reference Example 1 except that the electroplating conditions were changed as follows and the thickness of the second intermediate layer (tin-nickel alloy plating layer) was 3 μm.
(Electroplating conditions)
・ Use bath: Tin-nickel bath (EBALOY SNI manufactured by Sugawara Eugene Corporation)
・ PH: 2
・ Current density: 0.3 A / dm ²
・ Liquid temperature: 55 ℃
The aptitude of the produced separator was evaluated in the same manner as in Reference Example 5 . As a result, cracks were observed in the second intermediate layer, and it was confirmed that the bending workability was inferior to the separators of Reference Examples 1 and 5 .

  The present invention can be applied to the manufacture of a fuel cell in which a plurality of unit cells each having an electrode disposed on both sides of a solid polymer electrolyte membrane are connected.

It is a fragmentary sectional view showing one embodiment of a separator for fuel cells of the present invention. It is a fragmentary sectional view which shows other embodiment of the separator for fuel cells of this invention. It is process drawing for demonstrating one Embodiment of the manufacturing method of the separator of this invention. It is process drawing for demonstrating other embodiment of the manufacturing method of the separator of this invention. It is a partial block diagram for demonstrating an example of the polymer electrolyte fuel cell using the separator of this invention. It is a figure for demonstrating the membrane electrode assembly which comprises the polymer electrolyte fuel cell shown by FIG. FIG. 6 is a perspective view showing a state where the separator and the membrane electrode assembly of the polymer electrolyte fuel cell shown in FIG. 5 are separated from each other. FIG. 6 is a perspective view showing a state in which the separator and the membrane electrode assembly of the polymer electrolyte fuel cell shown in FIG. 5 are separated from a direction different from FIG. 7. It is a top view for demonstrating the other example of the polymer electrolyte fuel cell using the separator of this invention. It is a longitudinal cross-sectional view in the AA line of the polymer electrolyte fuel cell shown by FIG. It is a figure for demonstrating the membrane electrode assembly which comprises the polymer electrolyte fuel cell shown by FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Separator 2 ... Metal base | substrate 3 ... Groove part 4 ... 1st intermediate | middle layer 5 ... 2nd intermediate | middle layer 6 ... Resin layer 11 ... Separator 12 ... Metal base | substrate 13 ... Through-hole 14 ... 1st intermediate | middle layer 15 ... 2nd intermediate | middle layer 16 ... Resin layer 21, 51 ... Polymer electrolyte fuel cell 31,61 ... Membrane electrode assembly (MEA)
41A, 41B, 41C, 71A, 71B ... separator

Claims (7)

A metal base and a conductive resin layer formed by electrodeposition so as to cover the metal base through the first intermediate layer, the third intermediate layer, and the second intermediate layer, the metal base being made of aluminum or It is an aluminum alloy, the first intermediate layer is a nickel plating layer or a copper plating layer, the second intermediate layer is a tin plating layer or a tin alloy plating layer, and the third intermediate layer is formed with the first intermediate layer. A fuel that is interposed between the second intermediate layer and is a copper plating layer or a nickel plating layer, is made of a metal different from the first intermediate layer, and the resin layer contains a conductive material. Battery separator.   The separator for a fuel cell according to claim 1, wherein the metal substrate has a groove on at least one surface.   The separator for a fuel cell according to claim 1, wherein the metal substrate has a plurality of through holes.   The separator for a fuel cell according to any one of claims 1 to 3, wherein the conductive material is at least one of carbon particles, carbon nanotubes, carbon nanofibers, carbon nanohorns, and corrosion-resistant metals.   The tin alloy plating layer is a tin alloy plating layer of any one of tin-nickel, tin-copper, tin-cobalt, tin-silver, tin-zinc, tin-gold, and tin-bismuth. The separator for fuel cells according to any one of claims 1 to 4.   6. The fuel cell separator according to claim 5, wherein the tin alloy plating layer is made of tin-nickel and has a thickness in a range of 0.3 to 2 [mu] m. A metal substrate made of aluminum or an aluminum alloy is subjected to a zincate treatment, and then a first intermediate layer made of a nickel plating layer or a copper plating layer is formed on the metal substrate , and a copper plating layer or nickel is formed on the first intermediate layer Forming a third intermediate layer made of a plating layer and made of a metal different from the first intermediate layer, and forming a second intermediate layer made of a tin plating layer or a tin alloy plating layer on the third intermediate layer ; Then, on the second intermediate layer, a resin layer is formed by electrodeposition using an electrodeposition liquid in which a conductive material is dispersed in a resin having electrodeposition properties. Production method.

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