JPH08260178A - Water electrolytic cell using solid high molecular electrolyte membrane - Google Patents

Abstract

PURPOSE: To drastically reduce the production cost by forming a bipolar plate with the laminate of titanium alloy plate and stainless steel plate and arranging the stainless steel plate on the cathode side. CONSTITUTION: This filter press-type water electrolytic cell is formed with a main anode provided with filter press type electrolyte membranes on both ends, a main cathode, plural unit cells arranged between the electrodes in series and a clamping bolt and nut to integrate the unit cells. One cell is formed by a bipolar plate 9 on the anode side, an anode feeder 7, an electrode joining membrane 3, a cathode feeder 8 and an adjacent bipolar plate 9 on the cathode side. The electrode joining membrane 3 is formed with a solid high molecular electrolyte membrane. The bipolar plate 9 consists of a titanium alloy plate 28 and a stainless steel plate 29, and the stainless steel plate 29 is arranged on the cathode side. This water electrolytic cell is made cylindrical. The bipolar plate 9 is formed by integrating an electrode part consisting of a superplastic work and an outer-edge part consisting of resin. The expensive titanium alloy plate to be used is reduced in this way.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a water electrolysis cell for producing hydrogen and oxygen using a solid polymer electrolyte membrane.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, the structure of a filter press type water electrolysis cell for producing hydrogen and oxygen by water electrolysis using a polymer electrolyte membrane is as shown in FIG. (1) and the cathode main electrode (2), a plurality of unit cells arranged in series between these main electrodes (1) and (2), and tightening bolts and nuts that integrate them. ing. One cell is a bipolar plate
It consists of the anode side of (9), the anode power supply (7), the electrode junction film (3), the cathode power supply (8) and the cathode side of the adjacent bipolar plate (9).
The electrode assembly membrane (3) comprises an ion exchange membrane (4) and catalyst electrode layers (5) and (6) provided on both sides thereof. The number of unit cells is 80 to 600 in a commercial scale electrolytic cell.

In the electrolyzer having the above structure, when water is supplied into each unit cell from the water supply header (10) at the bottom of the electrolyzer, oxygen is generated on the surface of the catalyst electrode layers (5) and (6) on the anode side. Hydrogen is generated on the cathode side. The generated oxygen and hydrogen pass through the porous power feeders (7) (8), respectively, and the bipolar plate (9).
It reaches the anode side and the cathode side of the electrode, further reaches the upper part of the electrolytic cell through the vertical flow path provided in the bipolar plate, and is discharged to the outside through the oxygen header (11) and hydrogen (12) on the upper part of the electrolytic cell. It

Of these constituent members, it is the bipolar plate (9) that requires the most severe conditions. In other words, as a material condition, not only good conductivity but also an oxidizing atmosphere on the anode side and a reducing atmosphere on the cathode side, which are exactly opposite conditions, are required for one material. A further structural requirement is that the current be evenly transmitted to the power supply (7) (8),
In addition, it is required to have a function of ensuring a flow path through which the supply water and the generated gas can flow uniformly. At present, as a material satisfying such conditions, pure titanium is machined or pressed, or a thin plate of titanium alloy is superplastically processed, and the surface of the obtained workpiece is plated with platinum, or carbon is used. The one that is molded is used.

[0005]

However, of the above-mentioned conventional techniques, which is considered to be the most effective, a method for producing a bipolar plate by superplastic working of a titanium alloy thin plate,
There were the following problems.

(1) It is necessary to prevent hydrogen embrittlement by plating platinum on the cathode side of a superplastic processed titanium alloy thin plate.

(2) Hydrogen embrittlement cannot be completely prevented even if the cathode side of the superplastically processed titanium alloy thin plate is plated with platinum as described above.

(3) Titanium alloy is more expensive than stainless steel.

The present invention has been devised to solve the above problems, and can solve the problem of hydrogen embrittlement of a titanium alloy that cannot be avoided by superplastic working of a titanium alloy alone. It is an object of the present invention to provide a water electrolysis tank that can significantly reduce manufacturing costs.

[0010]

Means for Solving the Problems The inventors of the present invention, as a result of intensive research, have solved the above problems by forming a bipolar plate (9) with a laminated plate of a titanium alloy plate and a stainless steel plate. That is, the present invention has been completed.

The water electrolyzer according to the present invention comprises an anode main electrode (1) and a cathode main electrode (2) arranged at both ends, and these main electrodes.
(1) A plurality of unit cells arranged in series between (2) and a tightening tool that integrates these unit cells are provided, and one cell is
The anode side of the bipolar plate (9), the anode power feed (7), the electrode junction membrane (3) consisting of a solid polymer electrolyte membrane, and the cathode power feed (8)
In the filter press type water electrolysis tank, which consists of the cathode side of the adjacent bipolar plate (9), the bipolar plate (9) is composed of a laminate of titanium alloy plate and stainless steel plate, and the stainless steel plate is the cathode side. It is characterized by being placed so that it comes to.

The anode power feeder (7) is formed by diffusion bonding a titanium base material and a titanium fiber layer, for example. Examples of the titanium base material of the anode power feeder (7) include micromesh, photoetching treatment, punching plate and the like.

The cathode power feeder (8) is formed by plating a titanium base material with platinum. Examples of the titanium base material of the cathode power feeder (8) include micromesh, photoetching treatment, punching plate and the like. Hydrogen embrittlement is prevented by platinum-plating the titanium base material of the cathode power supply (8).

As the tightening tool, bolts and nuts for connecting flanges arranged at both ends are generally used.

The electrolytic cell preferably has a cylindrical shape from the viewpoint of increasing the operating pressure. A rectangular electrolytic cell can be used, but in this case, it is preferable to store it in a pressure vessel.

The bipolar plate (9) is preferably formed by integrally forming an electrode portion made of a superplastic work and an outer edge portion made of a resin. As the resin forming the outer edge portion, a fluorine resin, a polyimide resin, a polysulfone resin or the like having heat resistance and chemical resistance is preferable.

Cathode feed (8), bipolar plate (9) and anode feed
(7) is integrated by simultaneously forming the bipolar plate (9) by superplastic forming and diffusion bonding the cathode feed (8), bipolar plate (9) and anode feed (7) simultaneously. It is preferably molded. After forming the bipolar plate (9) by superplastic processing, multiple cathode feeds (8), multiple bipolar plates (9), and multiple anode feeds (7) are diffusion bonded. May be integrated by

It is also possible to use a cathode power feeder (8), an electrode part of a bipolar plate (9) made of a superplastic processed product, and an anode power feeder (7), which are integrated by an outer edge portion made of resin.

[0019]

In the water electrolysis cell according to the present invention, since the bipolar plate (9) is composed of a laminated plate of a titanium alloy plate and a stainless steel plate, the amount of expensive titanium alloy plate used can be reduced. Further, since the bipolar plate (9) is arranged so that the stainless steel plate is on the cathode side, it is not necessary to platinum-plat the cathode side of the bipolar plate (9) to prevent hydrogen embrittlement of the titanium alloy. . In this way, a significant reduction in manufacturing costs can be achieved.

[0020]

Embodiments of the present invention will be described below.

Example 1 FIG. 1 shows an exploded structural view of a most typical rectangular filter press type water electrolysis cell. As described above, the structure of the filter press type water electrolysis cell is the anode main electrode (1) arranged at both ends.
And a cathode main electrode (2), a plurality of unit cells arranged in series between these main electrodes (1) and (2), and four tightening bolts and nuts each integrating these unit cells. ing. One cell consists of the anode side of the bipolar plate (9), the anode feed (7), the electrode junction membrane (3), the cathode feed (8) and the cathode side of the adjacent bipolar plate (9). , Electrode assembly membrane (3)
Is composed of an ion exchange membrane (4) and catalyst electrode layers (5) and (6) provided on both sides thereof. The number of unit cells is 80 to 600 in a commercial scale electrolytic cell.

In the filter press type water electrolysis cell having the above-mentioned structure, the bipolar plate (9) is composed of a laminated plate of the titanium alloy plate (28) and the stainless steel plate (29), and the stainless steel plate (29) is on the cathode side. It is arranged to come.

In FIG. 1, (21) is a flange, (2)
2) is a nozzle plate, (23) is an insulating packing, (24) is an O-ring gasket, (25) is a porous spacer, and (26) is a seal gasket.

FIG. 2 is a plan view of the bipolar plate (9), FIG. 3 is a sectional view taken along the line aa in FIG. 2, FIG. 4 is a sectional view taken along the line bb, and FIG.
Section and FIG. 6 show dd section respectively. In this example, the bipolar plate (9) is a titanium alloy plate (28) and a stainless steel plate (2).
It is configured by subjecting the laminated plate of 9) to superplastic working, and is arranged so that the stainless steel plate (29) comes to the cathode side,
It satisfies all the requirements for bipolar plates. That is, in the aa cross section in FIG. 2, as shown in FIG. 3, the electrode assembly film (3), the anode power feeding body (7) and the cathode power feeding body are
(8) has a structure in which the gap between the peaks and valleys of the bipolar plate (9) is approximately 1 to 3 mm, and the peaks and valleys are alternately combined.
(7) The contact of (8) is maintained and the elasticity of the cell is obtained. Further, the valleys on the anode side and the cathode side serve as upward flow paths for oxygen and hydrogen, respectively. In FIG. 3, the peaks and the valleys have the same ratio, but it is also possible to set the interval between the peaks and the valleys to a ratio that facilitates mold release in superplastic working. Recesses (27) provided on the outer periphery of the bipolar plate (9)
Is a fitting groove of the O-ring gasket (24) for sealing. The upper and lower portions of the bipolar plate (9) are required to have the function of allowing fluid to freely flow in the vertical and horizontal directions and uniformly supporting the electrode assembly membrane (3). In this embodiment, as shown in FIG. 4 showing the bb cross section in FIG. 2, the electrode assembly membrane (3) is supported from both sides by a large number of substantially cubic projections, and the other portion functions as a flow path. To do.

In FIG. 2, the lower hole of the bipolar plate (9) is the water supply header (10), and the upper left hole is the oxygen header (1).
1). By processing these headers as shown in the cross section of FIG. 5, water is supplied to the anode side and the generated oxygen is discharged to the oxygen header (11). 5 and 6, a porous spacer (2) is provided between the bipolar plate (9) and the electrode assembly membrane (3) on the outer periphery of each header of the bipolar plate (9).
5) is interposed, the electrode assembly membrane (3) and another bipolar plate
A seal gasket (26) is interposed between (9).
Also, the hole on the upper right side of the bipolar plate (9) is the hydrogen header (12).
Then, this portion is processed as the cross section shown in FIG. 6 to discharge the generated hydrogen to the hydrogen header (12). It is desirable that the fluid flow uniformly in the central electrode portion of the bipolar plate (9). In the extreme case, if there is a drift, the part becomes dry, which causes an accident such as damage to the film. In this structure, it is possible to realize a more uniform flow by forming a large number of substantially cubic protrusions on the upper and lower parts of the bipolar plate (9) and by designing their distribution hydrodynamically. . Furthermore, by adjusting the porosity or width of the ring-shaped porous spacer (25) installed in each cell of the water electrolysis cell, specifically, the inlet header and the outlet header, the inflow amount of water into each cell can be adjusted. Can be uniform. If such a structure is adopted, the thickness of the unit cell will be about 2 to 3.5 mm.

Next, the operation of the water electrolysis cell having the above structure will be described.

First, the water supplied from the water supply header (10) at the lower part of the electrolytic cell passes through the porous anode power feeder (7) and the anode side catalyst electrode layer (in FIG. 7) of the electrode assembly membrane (3). (Five) )
Reach The electric power added here causes an electrolysis reaction of water to generate oxygen. The generated oxygen passes through the anode power supply (7) and rises along with unreacted water in the vertical flow path provided on the anode side electrode, and the oxygen header (1
It is discharged to the oxygen header (11) through the porous spacer (25) provided on the outer periphery of (1). On the other hand, electrode assembly membrane (3)
Hydrogen generated on the surface of the cathode side catalyst electrode layer ((6) in FIG. 7) and water permeating the ion exchange membrane ((4) in FIG. 7) pass through the porous cathode power supply body (8), It rises in the vertical flow path provided in the side electrode and is discharged to the hydrogen header (12) through the porous spacer (25) provided on the outer periphery of the hydrogen header (12) of the bipolar plate (9). .

The above description is for the case where the electrolytic cell is installed horizontally, but the effect is the same when the electrolytic cell is installed vertically.

Example 2 In Example 1, the shape of the water electrolysis cell was rectangular, but in this Example, the shape of the water electrolysis cell was cylindrical. The other structure is the same as that of the first embodiment.

The square type water electrolysis cell can be used only under the condition of relatively low operating pressure of 10 kg / cm ² or less. However, by changing the shape of the water electrolysis cell to 30 kg / c
It is possible to manufacture a water electrolysis cell that can withstand an operating pressure of about m ² .

Example 3 In the water electrolysis cell of Example 1, the bipolar plate (9) was a titanium alloy plate (2
By subjecting the laminated plate of 8) and the stainless steel plate (29) to superplastic processing, the whole is integrally molded, but conductivity is required only for the electrode part, and the surrounding part is water, There is a hole through which oxygen and hydrogen pass respectively, and conductivity is not necessary, and it is rather preferable that there is no conductivity in operation.

Therefore, in this embodiment, the bipolar plate (9) is
An electrode part made of a superplastic work and an outer edge part made of a fluororesin are integrally formed. The other structure is the same as that of the first embodiment.

Fourth Embodiment In the third embodiment, the bipolar plate (9) is integrally formed. In this embodiment, however, in the present embodiment, the cathode feeder (8), the bipolar plate (9) and the anode feeder.
(7) integrated by simultaneously forming the bipolar plate (9) by superplastic forming and diffusion bonding the cathode feed (8), bipolar plate (9) and anode feed (7) simultaneously. It is molded.

After forming the bipolar plate (9) by superplastic working, a plurality of cathode power feeding bodies (8) and a plurality of bipolar plates (9)
And a plurality of anode power feeders (7) may be integrated by diffusion bonding.

The other structure is the same as that of the first embodiment.

[0036]

Since the water electrolysis cell according to the present invention is constructed as described above, the following effects can be obtained.

In the water electrolyzer according to claim 1, the bipolar plate (9)
Since is composed of a laminated plate of a titanium alloy plate and a stainless steel plate, the amount of expensive titanium alloy plate used can be small, and the manufacturing cost can be greatly reduced.

Further, since the bipolar plate (9) is arranged so that the stainless steel plate is on the cathode side, there is no need to perform platinum plating for preventing hydrogen embrittlement of the titanium alloy, and in this respect also the manufacturing cost is high. Can be achieved.

Since the water electrolysis cell according to the second aspect is a cylindrical type, the operating pressure can be increased.

In the water electrolyzer according to claim 3, the bipolar plate (9)
Since the electrode part made of superplastic work and the outer edge part made of resin are integrally formed, only the electrode part has conductivity, and the present electrolytic cell facilitates the operation.

In the water electrolyzer according to claim 4, the cathode power supply body
(8), bipolar plate (9), and anode power supply (7) are integrally formed by simultaneous superplastic working and diffusion bonding, so the cell voltage can be lowered and the workability of assembly is improved. Can be improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a disassembled state of a rectangular filter press type water electrolysis cell.

FIG. 2 is a plan view showing the entire bipolar plate (9).

FIG. 3 is a partial cross-sectional view showing a cross section taken along line aa in FIG.

FIG. 4 is a partial cross-sectional view showing a cross section taken along line bb in FIG.

5 is a partial cross-sectional view showing a cross section taken along line cc in FIG.

FIG. 6 is a partial cross-sectional view showing a cross section taken along the line dd in FIG.

FIG. 7 is a schematic cross-sectional view showing a conventional rectangular filter press type water electrolysis cell.

[Explanation of symbols]

 1: Anode main electrode 2: Cathode main electrode 3: Electrode assembly film 4: Ion exchange membrane 5: Anode side catalyst electrode layer 6: Cathode side catalyst electrode layer 7: Anode power supply body 8: Cathode power supply body 9: Multipolar plate 10: Water supply header 11: Oxygen header 12: Hydrogen header 21: Flange 22: Nozzle plate 23: Insulating packing 24: O-ring gasket 25: Porous spacer 26: Seal gasket 27: Recessed line 28: Titanium alloy plate 29: Stainless steel plate

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Shoji Maezawa 2-8-11 Nishi-Shimbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building Incorporated Research Institute for Global Environment and Industrial Technology CO2 Immobilization Project Room (72 ) Inventor Inazumi, 2-8-11 Nishishinbashi, Minato-ku, Tokyo 7th Toyo Kaiji Building, Research Institute for Global Environmental Technology, CO2 fixation etc. project room (72) Inventor Moritaka Kato Minato-ku, Tokyo Nishishinbashi 2-8-11 7th Toyo Kaiji Building Incorporated Research Institute for Global Environment and Industrial Technology CO2 fixation etc. project room (72) Inventor Hiroaki Mori 2-8-11 Nishishinbashi, Minato-ku, Tokyo 7 Toyo Kaiji Building Inside the Project Office for CO2 fixation etc., Research Institute for Global Environmental Technology (72) Inventor Kei Oguro Osaka Prefecture Ikeda Midorigaoka 1-chome No. 8 No. 31 industrial technology Institute Osaka Industrial Technology Research Institute in

Claims (4)

[Claims] 1. An anode main electrode (1) and a cathode main electrode (2) arranged at both ends, and a plurality of unit cells arranged in series between these main electrodes (1) (2), and these unit cells. It has an integrated tightening tool, and one cell is the anode side of the bipolar plate (9),
A filter press type water consisting of an anode power feed (7), an electrode assembly membrane (3) made of a solid polymer electrolyte membrane, a cathode power feed (8), and the cathode side of the adjacent bipolar plate (9). In the electrolytic cell,
A water electrolysis cell using a solid polymer electrolyte membrane, characterized in that the bipolar plate (9) is composed of a laminated plate of a titanium alloy plate and a stainless steel plate, and is arranged so that the stainless steel plate is on the cathode side. 2. A cylindrical type.
The described water electrolysis cell. 3. The water electrolysis cell according to claim 1, wherein the bipolar plate (9) is an integrally molded product of an electrode part made of a superplastic work product and an outer edge part made of a resin. 4. The cathode power feed (8), the electrode part of the bipolar plate (9) made of a superplastic work, and the anode power feed (7) are integrated at the outer edge portion made of resin. The water electrolysis cell according to claim 1 in any one of claims 1 to 3.