JPH11329460A - Manufacture of separator for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a manufacturing method of a separator for a fuel cell, having the advantage of reducing variations the depth of gas passages, enabling problematic wear of a machining electrode to be eliminated, enabling the gas passages to be formed easily if they are made of a hard material. and enabling the gas passages with a plurality of depths and gradations to be formed easily. SOLUTION: This method is for manufacturing a separator for a fuel cell having recessed gas passages for allowing a gas including an active material to flow therethrough. A conducting member 3 having conductivity and acting as a separator and a machining electrode 16 having electrode projections 20 for excavating the gas passages 30 are prepared. The gas passages 30 are excavated by electrochemical machining in the conducting member 3 by causing an electric current to flow to the machining electrode 16 through the conducting member 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fuel cell separator, and more particularly to a separator using a conductive member as a base material.

[0002]

2. Description of the Related Art There has been provided a fuel cell which supplies fuel gas to generate power. A fuel cell is generally configured by stacking a number of battery cells. In order to further improve the performance of a fuel cell, it is required to reduce the variation in power generation and voltage for each battery cell. Factors of this variation include insufficient uniformity of the gas flow containing the active material,
Insufficient uniformity of catalytic activity of each electrode, insufficient uniformity of contact electric resistance, insufficient control of temperature distribution, and the like. Insufficient gas flow uniformity due to variations in the depth of gas passages in the separator is also considered to be one of the major factors.

In the industry, when forming a groove-shaped gas passage in a separator, a method of cutting a groove-shaped gas passage by machining a metal plate serving as a separator with a cutting tool has been conventionally used. There are known a method in which a plate is subjected to press working to form a groove-shaped gas passage, and a method in which a metal plate serving as a separator is subjected to etching to chemically dig a groove-shaped gas passage. A method of forming a gas passage by etching is disclosed in Japanese Patent Application Laid-Open No. Hei 4-26706.
No. 2 discloses this.

[0004]

However, in the conventional method of cutting a gas passage by machining with a cutting tool, if the precision is controlled, the depth of the gas passage can be made high, but the gas passage is machined little by little. Therefore, the processing speed is slow and the productivity is low. In particular, in the case of a separator using a hard material, which is not easily cut, as a base material, the processing time increases, and the productivity decreases. Further, even when the gas passage draws a complicated pattern shape, the processing time is prolonged, and the productivity is reduced. In addition, there is also a problem that the cutting tool is worn out by machining with the cutting tool. Further, a deteriorated layer which may be a factor of non-uniformity of conductivity or the like and a residual stress layer which may be a factor of dimensional change over time are easily generated.

In the conventional method of forming a gas passage by press molding, springback is likely to occur in the separator. Therefore, even if the fuel cell is assembled with high accuracy, the dimensional accuracy of the gas passage and the separator may be reduced due to springback. In the case of a fuel cell in which a number of separators are stacked together with battery cells, dimensional changes due to springback of the separator may be superimposed. Furthermore, since the pattern shape of the gas passage depends on the press formability, the design of the pattern shape of the gas passage is restricted by the press formability. Therefore, in designing the pattern shape of the gas passage, it is necessary to consider not only the viewpoint of uniform gas flow but also the ease of press forming. Furthermore, when the press mold is used for a long time,
Since the press mold is worn, the depth of the gas passage may fluctuate.

In the conventional method in which a gas passage is formed by etching, the depth of the gas passage tends to vary. Furthermore,
In the case of a gas passage having a plurality of depth dimensions, or a gas passage having an inclined gradation formed on the bottom surface, it cannot be easily formed by etching, and a complicated process is required. The present invention has been made in view of the above-described circumstances, is advantageous in reducing variation in the depth of the gas passage, can also eliminate the problem of abrasion of the processing electrode, and further, a hard separator is difficult to cut. Even when a material is used as a base material, a gas passage can be easily formed, a processing speed can be secured, and in addition, a gas passage having a plurality of depths or gradation depths can be easily formed. An object of the present invention is to provide a method of manufacturing a fuel cell separator having an effect.

[0007]

Means for Solving the Problems The present inventors have intensively developed the formation of the gas passage of the separator of the fuel cell.
Then, it was found that forming a gas passage based on electrolytic processing is advantageous for achieving the above-mentioned problem, and the results were confirmed by a test. Thus, the method of the present invention was completed. The method for manufacturing a fuel cell separator according to the present invention is a method for manufacturing a fuel cell separator having a concave gas passage through which a gas containing an active material flows, comprising: a conductive member having conductivity as a separator; and a gas passage. A process of preparing a processing electrode having an electrode projection having a shape corresponding to the pattern shape of the above, and a process in which the conductive member and the electrode projection of the processing electrode are opposed to each other, and an electrolytic solution is interposed therebetween. A process of supplying power between the member and the processing electrode, eluting the conductive member, performing electrolytic processing, and digging a gas passage in the conductive member.

If power is supplied between the conductive member and the processing electrode,
Electrolytic processing in which the conductive member is electrochemically eluted is performed, and a groove-shaped gas passage is dug in the surface of the conductive member.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The material of a conductive member serving as a separator used in the method of the present invention is a material having conductivity, and a conventionally used material can be adopted. Steel, aluminum, titanium, copper, etc. can be used. Austenitic, ferritic and martensitic stainless steels can be used. Although the shape of the conductive member is not particularly limited, a plate-shaped member can be generally employed.

The working electrode used in the method of the present invention has an electrode projection for electrochemically digging a gas passage. The material may be any material having conductivity, for example, a copper-based material. Although the protrusion amount of the electrode protrusion can be appropriately selected, for example, the upper limit is 0.5 mm, 1 mm, or 3 m.
m, 10mm, the lower limit is 0.1mm, 0.2mm
However, the present invention is not limited to these.

In the method of the present invention, power is supplied between the conductive member and the processing electrode in a state where the conductive member and the processing electrode are opposed to each other and an electrolytic solution is interposed between the two, and the conductive member is eluted by eluting the conductive member. Processing is performed to form a gas passage in the conductive member.
In the method of the present invention, power is supplied between the conductive member and the processing electrode. In this case, generally, the processing electrode is set on the cathode, and the conductive member, which is the workpiece, is set on the anode. The current density can be appropriately selected according to the type of the conductive member and the like, but can be, for example, 0.1 to 200 A / cm ² , but is not limited thereto. As the electrolytic solution, those commonly used in electrolytic processing can be employed, and for example, a NaNo ₃ solution can be employed. The temperature of the electrolyte can be appropriately selected, for example, 10 to 40 ° C.,
It is not limited to this.

According to the method of the present invention, a removing operation for removing electrolytic products can be performed at least at one time during electrolytic processing. Removal of the electrolytic product in this way is more advantageous for uniformity of electrolytic processing. The removal operation includes:
The power supply of the pulse waveform current may be performed when the power supply is stopped as in the case of the valley of the pulse waveform current, or may be performed during the power supply. The removal operation can be performed, for example, by ejecting the electrolytic solution using an ejection means such as a pump. The time at the peak and the time at the valley of the pulse, and their ratio, can be appropriately selected as needed.

According to the method of the present invention, the protrusion amount of the electrode projection of the processing electrode can be adjusted according to the position of the gas passage. According to this, a gas passage having a plurality of depths can be easily formed. Therefore, according to the method of the present invention, the protrusion amount of the electrode projection of the processing electrode can be adjusted so as to form a gradation on the bottom surface of the gas passage. Further, the amount of protrusion of the electrode projection of the processing electrode can be adjusted so that a shallow portion or a deep portion is partially formed on the bottom surface of the gas passage.

[0014]

Embodiments will be described below with reference to the drawings. First, the electrolytic processing apparatus 1 will be described with reference to FIG.
The electrolytic processing apparatus 1 includes a processing tank 11 in which an electrolytic solution 10 is stored.
A base 12 disposed at the bottom of the processing tank 11 and having an installation surface 12a; an elevating head 13 capable of moving up and down with respect to the base 12; a driving source 14 for moving the elevating head 13 up and down; A processing electrode 16, a processing power supply 17 (DC power supply), a current control section 18, and an ejection section 19 having an ejection port 19 a for ejecting the electrolytic solution 10. Have.

The electrolyte 10 is a sodium nitrate solution (concentration:
40% by weight). The base 12 is connected to the anode side. The processing electrode 16 is connected to the cathode side. An electrode projection 20 having a pattern substantially corresponding to the pattern of the gas passage 30 is formed on the processing electrode 16. The tip end surface of the electrode projection 20 is coated with a conductive plating film 21 (platinum-based) for improving corrosion resistance.
As schematically shown in FIG.
a, masking film 22 on side surface 20a of electrode projection 20
(Thickness: 3 to 10 μm). The masking film 22 has electric insulation and durability to the electrolyte 10. Therefore, in the processing electrode 16, current flows intensively on the front end surface 20 c of the electrode projection 20.

In this embodiment, a conductive plate 3 (thickness: 1 mm) made of austenitic stainless steel (JIS-SUS304), which is a metal plate, is used as a conductive member.
As shown in FIG. 2, a portion of the surface 3 s of the conductive plate 3 other than the portion serving as the gas passage 30 is provided with a masking film 23.
Is coated. Note that, as in the example schematically shown in FIG.
The ceiling surface 16a of the processing electrode 16, the side surface 20 of the electrode projection 20
Although a may be coated with the masking film 22, the masking film may not be coated on the surface 3 s of the conductive plate 3.

In the electrolytic processing, the conductive plate 3
Is set on the installation surface 12a of the base 12 on the anode side.
In this case, the conductive plate 3 is brought into close contact with the base 12. Therefore, the conductive plate 3 becomes an anode. In this state, the entire conductive plate 3 is immersed in the electrolyte 10. The conductive plate 3 may be directly connected to the anode terminal. In a state where the conductive plate 3 and the processing electrode 16 are opposed to each other, a fine gap, generally 0.2 to 0.3
Gradually lower to maintain a gap of mm. Although the conductive plate 3 and the processing electrode 16 are close to each other, they are not in contact with each other.
Electric power is supplied between the conductive plate 3 and the processing electrode 16 to elute a portion of the conductive plate 3 on the anode side, which becomes the gas passage 30, to perform electrolytic processing. By the electrolytic processing, a gas passage 30 (target depth: 0.4 mm) having a pattern shape corresponding to the electrode projection 20 of the processing electrode 16 is formed.

FIG. 2 schematically shows the shape of the gas passage 30 inferred. The gas passage 30 has a bottom surface 30e and a side surface 30f. In the present embodiment, in the electrolytic processing, the temperature of the electrolytic solution 10 was about 20 ° C., and a pulse current I having a current density of 40 A / cm ² or more was passed. The pulse current I is the peak I _m
Exhibits a pulse-like waveform with (20 msec) and the troughs I _v (5sec). Current density when the crest I _m is about 4
0 A / cm ² . When valleys I _v, current is not substantially feed.

[0019] When the valley I _v, the ejection driving means 19c such as a pump is operated to eject the electrolyte 10 from the ejection port 19a of the ejection portion 19. Thus, a removing operation for removing the electrolytic product is performed. In this embodiment, if necessary, the processing electrode 16 can be appropriately raised so as to increase the gap between the conductive plate 3 and the processing electrode 16 in order to improve the removal of the electrolytic product.

(Main effects of the embodiment) The gas passage 3 is formed by electrolytic processing.
According to the present embodiment in which 0 is formed, it is advantageous to suppress variations in the depth of the gas passage 30 formed in the conductive plate 3.
According to the test by the inventor, when the target depth dimension of the gas passage 30 is 0.4 mm, plus or minus 0.005 m
m, that is, the dispersion of the depth of the gas passage 30 can be reduced with extremely high accuracy of about 1.25%. For this reason, even in a fuel cell in which a large number of battery cells are stacked, it is possible to reduce the variation in the gas flow including the active material in each battery cell. Therefore, variations in power generation and voltage in each battery cell can be reduced, which is advantageous for improving the performance of the fuel cell.

When the gas passage 30 is formed by press molding, the press die is worn, and therefore, there is a problem that the depth of the gas passage 30 varies due to the wear. However, according to this embodiment, since the processing electrode 16 and the conductive plate 3 are in a non-contact state, a high mechanical load does not act on the processing electrode 16, and thus the consumption and damage of the processing electrode 16 can be suppressed. The electrode projections 20 of the processing electrode 16 can be used for a long time. For example, it can be used semi-permanently. Also in this sense, it is advantageous to suppress the variation in the depth of the gas passage 30.

Further, in this embodiment, the accuracy of the groove width of the gas passage 30 can be improved. For example, when the target groove width of the gas passage 30 is 1.2 mm, the value can be set to ± 0.005 mm. When the gas passages 30 are cut by machining, the gas passages 30 having a complicated pattern shape cannot be formed together, and the gas passages 30 having a complicated pattern shape are formed little by little, so that the processing time becomes long. . However, according to the present embodiment in which the electrolytic processing is performed, even if the gas passage 30 has a complicated pattern shape, the entire gas passage 30 is formed by the processing electrode 16 having the electrode projection 20 corresponding to the pattern shape of the gas passage 30. Can be formed together, so that the gas passage 3
This is advantageous in shortening the time for machining 0, and can contribute to improvement in productivity.

In the electrolytic processing, the processing speed is affected by the current value. Therefore, if the current value is increased, it is more advantageous to shorten the time for forming the gas passage 30. According to the test by the present inventors, the conductive plate 3 having a flat shape of 200 mm × 200 mm was used.
In forming the gas passage 30 having a depth of 0.4 mm, when the above-described pulse current was supplied, the time required for one sheet was as short as several minutes.

In addition, according to this embodiment, even when the depth of the gas passage 30 differs depending on the position of the gas passage 30, for example, the gas passage 30 may have a plurality of depths. Alternatively, even when the bottom surface 30e of the gas passage 30 has a gradation, the gas passage 30 can be formed with a small number of electrolytic machining operations, usually with one electrolytic machining operation, thereby improving productivity. obtain.

Further, according to the present embodiment in which the gas passage 30 is formed by electrolytic processing, it is advantageous to smooth the bottom surface 30e of the gas passage 30 and reduce the surface roughness of the bottom surface 30e. Furthermore, since the surface of the gas passage 30 becomes very smooth,
Even if the conductive plate 3 is made of stainless steel, intergranular corrosion hardly occurs. According to the test by the inventor, the gas passage 3
The surface roughness Rz of the 0 bottom surface 30e was extremely small at 1 μm or less. According to the test by the inventor, the working electrode 16
The surface roughness Rz of the electrode projection 20 of the gas passage 30
It has been confirmed that the surface roughness Rz of the bottom surface 30e of the above decreases by one digit, that is, about 1/8 to 1/15.

In addition, according to the present embodiment, the ceiling surface 16a of the processing electrode 16 and the side surface 20a of the electrode projection 20 are coated with the masking film 22 having electrical insulation. Therefore, a virtual line PW extending the side surface 30f of the gas passage 30 is represented by
This is advantageous in that the conductive plate 3 is set upright on the surface 3s. This is even more so because the masking film 23 is coated on the surface 3 s of the conductive plate 3 other than the portion serving as the gas passage 30.

(Surface Roughness Test) In the case where the gas passage 30 was formed in the conductive plate 3 by electrolytic processing, a test for measuring the surface roughness of the bottom surface 30e of the gas passage 30 was performed. In this test, the surface roughness of the processing electrode 16 was 3.2 μm in Rz, and the conductive plate 3 was austenitic stainless steel.
The target depth of the gas passage 30 is 0.4 to correspond to the current product.
mm. The test results are shown in FIG. The vertical axis in FIG. 4 indicates the surface roughness, and the horizontal axis indicates the distance. As shown in FIG. 4, the characteristic line indicating the surface roughness characteristic was flat and smooth. The surface roughness is extremely small, Ra = 0.08
61 μm, Rmax = 0.5320 μm, Rz = 0.30
It was 00 μm. These are based on JIS standards and Ra
Means a center line average roughness, Rmax means a maximum height, and Rz means a 10-point average roughness. The surface roughness of the bottom surface 30e of the gas passage 30 formed by the electrolytic processing as described above was extremely small, and the Rz was about 1/10 of the surface roughness of the processing electrode 16.

As a comparative example, the same type of conductive plate was used, and gas passages having the same depth were formed by etching. A test for measuring the surface roughness was also performed on the comparative example. The test results are shown in FIG. The vertical axis in FIG. 5 indicates the surface roughness, and the horizontal axis indicates the distance. As shown in FIG. 5, the characteristic line indicating the surface roughness characteristic had large irregularities. The surface roughness is considerably larger than that of electrolytic processing, and Ra = 0.48.
65 μm, Rmax = 3.8160 μm, Rz = 2.84
It was 40 μm.

Based on the above test results, the ratio of Ra by electrolytic processing and Ra by etching is 0.08
61 μm / 0.4865 μm ≒ 0.18 (about 18%). Rmax by electrolytic processing and R by etching
The ratio to max is 0.5320 μm / 3.881610.
μm ≒ 0.14 (about 14%). The ratio of Rz by electrolytic processing to Rz by etching is 0.3000
μm / 2.8440 μm ≒ 0.11 (about 11%). As described above, it was found that the surface roughness by the electrolytic processing was 10 to 20% as compared with the surface roughness by the etching, and was extremely small.

(Application Example) FIG. 6 shows a plan view of a separator formed from the conductive plate 3 described above. In this example, the separator 5 is formed by covering the above-described conductive plate 3 with a rubber layer 50 having a seal protrusion 50r. In the separator 5, a fuel gas inlet 51 and a fuel gas outlet 52 penetrating in the thickness direction are formed at diagonal positions. Further, an air inlet 53 and an air outlet 54 penetrating in the thickness direction are formed at diagonal positions. Furthermore, the cooling medium passage 5 penetrating in the thickness direction
5. The cooling medium passage 56 is formed at a diagonal position. The fuel gas introduced from the fuel gas inlet 51 basically flows toward the fuel gas outlet 52 along the directions of arrows K1, K2, K3, K4, and K5.

FIG. 7 is a view taken along the line W7-W7 in FIG. FIG.
Indicates the view from the arrow W8-W8 when assembled. FIG.
As shown in (1), a battery cell 6 is constituted by sandwiching a positive electrode 61 and a negative electrode 62 on a solid electrolyte membrane 60 made of a polymer material having proton permeability. The separators 5 are stacked on both sides of the battery cell 6. As a result, a positive electrode chamber 61c facing the positive electrode 61 is formed, and a negative electrode chamber 62c facing the negative electrode 62 is formed. A gas (hydrogen-containing gas) containing a negative electrode active material flows through the negative electrode chamber 62c. A gas (air) containing a positive electrode active material flows through the positive electrode chamber 61c. A large number of such battery cells 6 and separators 5 are stacked to constitute a fuel cell.

The gas passage 30w on the inlet side directly connected to the fuel gas inlet 51 is made deeper than the other gas passages 30. The outlet gas passage 30 x directly connected to the fuel gas outlet 52 has a greater depth than the other gas passages 30. Therefore, as shown in FIG. 9, the gas passages 30x and 30w in the machining electrode 16 for performing the electrolytic machining.
The protrusion amount H2 of the electrode protrusion 20r for forming the second electrode protrusion 20r is larger than the protrusion amount H1 of the other electrode protrusion 20. This enables two-step digging.

In this application example, the depth of the gas passage 30 may be as shown in FIG. 10 or as shown in FIG.
1 or the embodiment shown in FIG. 12 or the embodiment shown in FIG. 10 to 13, the characteristic lines S1, S2, S
3, S4 indicates the depth of the gas passage 30, and the characteristic lines M1, M
2, M3 and M4 mean the protruding amounts of the electrode protrusions 20 of the processing electrode 16.

In the embodiment shown in FIG. 10, the characteristic line S1
Thus, even if the position of the gas passage 30 changes, the gas passage 3
The depth of the 0 bottom surface 30e is the same. In this case,
As shown by the sex line M1, the position of the gas passage 30 changes.
Also, the protrusion amount of the electrode protrusion 20 of the processing electrode 16 is the same.
You. In the mode shown in FIG. 11, as shown by the characteristic line S2,
A gradation is formed on the bottom surface 30e of the gas passage 30.
ing. In this embodiment, the fuel gas is supplied from the fuel gas inlet 51.
Towards the exit 52, that is, arrows K1, K2, K
3, along the direction of K4, K5, in other words, the gas flow
From the upstream side to the downstream side of the gas passage 30.
The gradation is formed so that the depth of e gradually becomes shallower
Have been. That is, it can be understood from the characteristic line S2 in FIG.
As shown in FIG.₁, A_Two, A _Three→ Position b₁, B
_Two, B_Three→ Position c₁, C_Two, C_Three→ Position d₁, D_Two, D_Three→ Position
e₁, E_Two, E_Three→ Position f₁, F_Two, F_ThreeGas passage 3
The depth of the 0 bottom surface 30e becomes shallower.

In this case, the electrode projection 2 of the machining electrode 16
0 has gradation. That is, FIG.
As can be understood from the characteristic line M2, the positions a ₁ , a ₂ ,
a ₃ → positions b ₁ , b ₂ , b ₃ → positions c ₁ , c ₂ , c ₃ → positions d ₁ , d ₂ , d ₃ → positions e ₁ , e ₂ , e ₃ → positions f ₁ , f ₂ , f
_In the order of ₃ , the protrusion amount of the electrode projection 20 of the processing electrode 16 decreases.

In the embodiment shown in FIG. 12, gradation is formed on the bottom surface 30e of the gas passage 30, as shown by the characteristic line S3. In this embodiment, as going from the fuel gas inlet 51 to the fuel gas outlet 52, the arrows K1, K
The gradation is formed such that the depth of the bottom surface 30e of the gas passage 30 gradually increases from the upstream side to the downstream side of the gas flow along the directions of K2, K3, K4, and K5. That is, as can be understood from the characteristic line S3 in FIG. 12, the positions a ₁ , a ₂ , a ₃ → the positions b ₁ , b ₂ ,
b ₃ → positions c ₁ , c ₂ , c ₃ → positions d ₁ , d ₂ , d ₃ → positions e ₁ , e ₂ , e ₃ → positions f ₁ , f ₂ , f ₃ in that order.
0 becomes deeper.

In this case, the electrode projection 2 of the machining electrode 16
0 has gradation. That is, FIG.
As can be understood from the characteristic line M3 of FIG. ₂ , the positions a ₁ , a ₂ ,
a ₃ → positions b ₁ , b ₂ , b ₃ → positions c ₁ , c ₂ , c ₃ → positions d ₁ , d ₂ , d ₃ → positions e ₁ , e ₂ , e ₃ → positions f ₁ , f ₂ , f
_In the order of ₃ , the protrusion amount of the electrode projection 20 of the processing electrode 16 increases.

In the embodiment shown in FIG. 13, a shallow portion is formed in the gas passage 30 as shown by the characteristic line S4. In this case, as shown by the characteristic line M4, the protrusion amount of the electrode protrusion 20 of the processing electrode 16 corresponding to the shallow portion of the gas passage 30 is made smaller than the other protrusion amounts. Unlike the etching process, according to the electrolytic process, the processed electrode 16
By changing the projection amount of the electrode projection 20 according to the position of the gas passage 30, the depth of the gas passage 30 can be easily changed in various modes as described above.

The gas containing the active material is supplied to the gas passage 3
It is considered that the active material is consumed more on the downstream side than on the upstream side as it flows through 0, so that the concentration of the active material tends to decrease. In this regard, as shown in FIG. 11, by forming a gradation in which the gas passage 30 becomes shallower from the upstream side to the downstream side, an effect corresponding to a decrease in the concentration of the active material in the gas flowing through the gas passage 30 can be expected.

Further, products may be generated in the gas passage 30. For example, when the gas passage 30 is a passage through which air flows, generated water may be generated in the gas passage 30, and therefore, the passage volume on the downstream side may be increased. In this regard, by forming a gradation in which the gas passage 30 becomes deeper from the upstream side to the downstream side as shown in FIG. 12, the downstream passage volume can be increased without changing the width of the gas passage 30.

Further, in the embodiment shown in FIG.
A shallow portion is locally formed. In a shallow part, the cross-sectional area of the passage is partially reduced. Therefore, the flow velocity fluctuation accompanying the decrease of the passage cross-sectional area can be expected, and the discharge of the product can be expected.

[0042]

According to the method of the present invention, the variation in the depth of the gas passage can be reduced. Therefore, even if the number of separators manufactured increases, variation in the depth of the gas passage can be suppressed. Therefore, even when a fuel cell is formed by stacking a large number of battery cells, it is advantageous in making the flow of the gas containing the active material uniform in each battery cell. Therefore, it is advantageous for reducing the variation in power generation and voltage in each battery cell, and can contribute to improving the performance of the fuel cell.

According to the method of the present invention, unlike the case where the gas passage is formed by press molding, a large load does not act on the processing electrode when forming the gas passage, and the consumption of the processing electrode itself is suppressed. obtain. Therefore, once the processing electrode is manufactured, the processing electrode can be used for a long time.
For example, a working electrode can be used semi-permanently. Therefore, it is possible to suppress the fluctuation of the gas passage due to the wear of the machining electrode.

Further, according to the method of the present invention employing electrolytic processing, the influence of the hardness of the conductive member serving as the separator can be reduced or avoided when forming the gas passage. Therefore, the gas passage can be accurately formed even with a hard conductive member. Therefore, although it has good corrosion resistance and is preferable as a material of the separator, it is advantageous for forming a gas passage in a conductive member formed of an alloy material (for example, stainless steel) which is not always easy to press-mold or machine.

Further, according to the method of the present invention, the protrusion amount of the electrode projection of the processing electrode can be adjusted according to the position of the gas passage.
In this case, the depth of the gas passage can be changed according to the position of the gas passage. That is, a gas passage having a plurality of depths or a gas passage having a gradation can be easily formed in, for example, one step as compared with the case where the gas passage is formed by etching.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a state in which electrolytic processing is performed.

FIG. 2 is an enlarged view of the vicinity of an electrode protrusion of a processing electrode.

FIG. 3 is an enlarged view of the vicinity of an electrode protrusion of a processing electrode according to another embodiment.

FIG. 4 is a graph showing the surface roughness of a gas passage formed by electrolytic processing.

FIG. 5 is a graph showing the surface roughness of a gas passage formed by etching as a comparative example.

FIG. 6 is a plan view of a separator according to an application example.

FIG. 7 is an arrow view along the line W7-W7 in FIG. 6;

FIG. 8 is an arrow view along the line W8-W8 in FIG. 6;

FIG. 9 is a cross-sectional view of a main part schematically showing a state where electrolytic processing is performed around the multi-stage gas passage.

FIG. 10 is a graph showing a mode of a depth of a gas passage and a projection amount of an electrode projection.

FIG. 11 is a graph showing another aspect of the depth of the gas passage and the amount of protrusion of the electrode protrusion.

FIG. 12 is a graph showing another aspect of the depth of the gas passage and the amount of protrusion of the electrode protrusion.

FIG. 13 is a graph showing another aspect of the depth of the gas passage and the projection amount of the electrode projection.

[Explanation of symbols]

In the figure, 16 is a processing electrode, 20 is an electrode projection, 3 is a conductive plate,
Reference numeral 30 denotes a gas passage.

Claims (3)

[Claims] 1. A method of manufacturing a fuel cell separator having a concave gas passage through which a gas containing an active material flows, wherein the conductive member has a conductive property to be a separator and corresponds to a pattern shape of the gas passage. A step of preparing a processing electrode having an electrode projection having a shape, and facing the conductive member and the electrode projection of the processing electrode,
Power supply between the conductive member and the processing electrode in a state where an electrolytic solution is interposed therebetween, performing electrolysis by eluting the conductive member, and digging the gas passage in the conductive member; A method for producing a fuel cell separator, comprising: 2. The method for manufacturing a fuel cell separator according to claim 1, wherein a removing operation for removing an electrolytic product is performed at least at one time during the electrolytic processing. 3. The process according to claim 1, wherein the amount of protrusion of the electrode projection of the processing electrode is adjusted in accordance with the position of the gas passage, and the depth of the gas passage is adjusted in accordance with the position of the gas passage. A method for manufacturing a fuel cell separator, comprising: