JPH0995791A - Solid polyelectrolyte water electrolyzer and its electrode structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid polyelectrolyte water electrolyzer capable of reducing the production cost, and also capable of improving a generating efficiently of ozone, oxygen, etc., per volume by increasing a unit scale of an electrode and to provide its cathode power feeding plate in a bipolar solid polyelectrolyte water electrolyzer. SOLUTION: In the bipolar solid polyelectrolyte water electrolyzer 1 using a polyelectrolyte film 2 as the solid electrolyte, the cathode power feeding plate being in press-contact with an cathode side of the polyelectrolyte film 2 is formed with a conductive porous structure having <=17,000kgf/cm<2> compressive elastic modulus. In this way, the film prolonging a life is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water electrolysis apparatus and a method thereof, and more particularly to a solid polymer water electrolysis apparatus capable of generating ozone or oxygen and hydrogen by using a solid polymer electrolyte membrane and an electrode thereof. Regarding the structure.

[0002]

2. Description of the Related Art Conventionally, this type of water electrolysis is generally called solid polymer electrolyte water electrolysis, in which a fluororesin ion exchange membrane (sulfonic acid type) is used instead of an electrolyte solution as a proton conductive solid electrolyte. Is used as.

A very common type of water electrolysis cell for hydrogen and oxygen generation is to stack a grooved separator plate with an expanded metal or other porous power supply plate made by another method, and ionize this. It is configured by pressing a bonded body in which a catalyst electrode is bonded to an exchange membrane (for example, General Electric Company. Electrochemical Hydorogen Technologies. Haru
mut, Wendt, 1998, p. 200 Elsevier).

Alternatively, Japanese Patent Laid-Open No. 55-119186
In the issue, a polyelectrolyte structure in which a porous conductive material obtained by plating a polymer electrolyte membrane with platinum, for example, a titanium sintered body, a nickel sintered body, or porous graphite is directly pressure-welded to a negative or anode power feeding plate. And an electrolysis device is disclosed.

As an electrolytic cell for ozone production, Japanese Patent Laid-Open No. 2-259090 discloses a porous plate made of nickel or a nickel alloy, one side of which is coated with platinum, on the cathode side of an ion exchange membrane to form an anode. There is disclosed a method for electrolytic production of ozone in which a lead dioxide-coated porous titanium electrode is arranged on the side and pressure is applied from both sides to perform zero gap electrolysis.

[0006]

However, in the prior art, when the grooved separation plate is made to have a thickness of several mm (for example, 1 to 3 mm), the processing deformation is large and the separation film is uniform with the film. There is a problem in that the flatness required for contact cannot be obtained, and the separator itself must be made thicker, which significantly increases the weight and volume of the bipolar electrolytic cell.

On the other hand, as for the negative and positive power feeding plates in contact with the separating plate, those which are conventionally stacked with expanded metal, those which are formed by powder sintering method, or sintered bodies of fibrous metal by chattering method, porous carbon Although boards are used,
Using these, when assembling a bipolar electrolytic cell in a multi-layer, it is extremely difficult to completely obtain a uniform contact state over all locations with the polymer electrolyte membrane, and burnout of the membrane,
It leads to a short life, and it is impossible to make a practical device in the increase in size and the number of layers.

That is, when the pressure contact force of the multi-layer bipolar electrode electrolysis cell is insufficient, the contact with the membrane can be locally obtained, and the current is concentrated there to cause burning of the membrane. Further, when the pressure contact force is increased, the contact with the film locally becomes excessive and the film is damaged,
Further, among the above-mentioned materials, there are some materials such as a powder sintered body and a porous carbon plate which are lacking in flexibility and have high brittleness, and thus crack.

In addition, when lead dioxide is used for the anode power feeding plate to carry out electrolytic synthesis of ozone, the lack of pressure contact force similarly causes the film to burn out, and if this pressure contact force is increased, the film and There is also a problem that the electrolysis efficiency of ozone is significantly reduced even if the power supply plate is not mechanically damaged.

In order to solve the above problems, the present invention is a bipolar electrode solid polymer electrolyte water electrolysis apparatus, which reduces the manufacturing cost, is lightweight even when the electrode is enlarged, and is ozone and oxygen per volume. An object of the present invention is to provide a solid polymer electrolyte water electrolysis device and a cathode power supply plate thereof, which can improve the generation efficiency of water.

[0011]

The above-mentioned problems of the present invention are as follows.
In a bipolar solid polymer electrolyte water electrolysis apparatus using a polymer electrolyte membrane as a solid electrolyte, the cathode power supply plate pressed against the cathode side of the polymer electrolyte membrane has a compression elastic modulus of 170.
It is achieved by a solid polymer electrolyte water electrolysis apparatus characterized by being formed of a conductive porous structure having a weight of 00 kgf / cm ² or less.

Further, the electrode structure for a bipolar solid polymer electrolyte water electrolysis apparatus using a polymer electrolyte membrane as a solid electrolyte, wherein the cathode power supply plate is made of a sintered body of stainless fiber, and / Alternatively, it is achieved by a cathode power supply plate having a structure in which a groove is formed on one surface.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an embodiment of a solid polymer electrolyte water electrolysis apparatus according to the present invention. In this solid polymer electrolyte water electrolysis apparatus 1, a circular solid polymer electrolyte membrane 2 is sandwiched between a disk-shaped anode power feed plate 3 and a disk-shaped cathode power feed plate 4 (see FIGS. 2 and 3) to form a separation plate 6. It is provided with a plurality of polymerized compounds. On both ends of the polymer, a power supply plate 8a having terminals 7 in order from the inside,
8b, disk-shaped flange 10 via insulating plates 9a, 9b
a, 10b are arranged, bolts 11 ... 11 and nut 1
A bipolar structure is used in which the cells 5 ... 5 are fixed by fastening them by 2 ... 12.

The flange 10b has a first port 13 for supplying pure water for electrolysis, a second port 14 for discharging oxygen gas or ozone gas generated by electrolysis together with pure water, and hydrogen generated by electrolysis. A third port 15 is provided for discharging gas. In the illustrated apparatus, the power supply plate 8a is on the anode side.

The cell 5 has an anode power feed plate 3 sandwiching a solid polymer electrolyte membrane 2 as shown in vertical cross sections in FIGS. 3 and 4.
Casing rings 16 and 17 forming a casing are externally fitted to the cathode power feeding plate 4. Solid polymer electrolyte membrane 2
For example, a perfluorosulfonic acid-type cation exchange membrane (Dafon's trade name Nafion, etc.) is used as (hereinafter, simply referred to as an electrolyte membrane), which selectively permeates cations by applying a voltage. It is a cation permeable membrane.

The electrolyte membrane 2 has ports 13, 14,
Three holes 2a, 2b, 2c are formed at positions overlapping with 15 (see FIG. 2).

Since the electrolyte membrane 2 is strongly acidic, the anode power feeding plate 3 is made of a corrosion-resistant titanium plate, a titanium powder sintered body, a titanium expanded body, or a porous sintered body such as niobium, tantalum or platinum. Can be formed,
From the viewpoint of electrical conductivity, porosity, etc., it is preferable to form the titanium fiber sintered body.

On the surface of the anode power supply plate 3 which is not in contact with the electrolyte membrane 2, a pure water flow path is formed and a plurality of parallel grooves 18 are formed in order to facilitate the flow of generated oxygen gas. (See FIGS. 2 and 5).

When the apparatus 1 is used as an ozone generating apparatus, the anode power feeding plate 3 deposits lead dioxide on the contact surface with the electrolyte membrane 2, but when it is used for the purpose of generating oxygen / hydrogen. Plating with platinum.

The cathode power supply plate 4 can be formed by using a stainless fiber sintered body, nickel, an alloy thereof, carbon or the like in a fibrous shape and porous and sintered. A stainless fiber sintered body is more preferable because it is easy to handle. A carbon film having a thickness of 50 to 200 μm may be interposed on the contact surface with the electrolyte membrane 2 in order to improve electric conduction.

As the stainless fiber sintered body, one obtained by sintering strip-shaped stainless fibers or hair-shaped stainless fibers is used, and since there is no fear of hydrogen embrittlement, it is suitable for a cathode power supply plate that generates hydrogen. . The stainless fiber sintered body is
Sintering is performed using a stainless short fiber having a thickness of 20 to 100 μm and a length of 1 to 20 mm, or a stainless steel long fiber having a thickness of 4 to 20 μm and a porosity of 50 to 90%, preferably 70 to 80. %. In such a stainless fiber sintered body, a fibrous metal is filled in a molding die, and a molding pressure 1
After molding by applying from 100 to 1000 kg / cm ² , a sintered body is obtained by heating at about 1200 ° C. and sintering in a reducing atmosphere.

The stainless sintered body thus obtained has a compressive elastic modulus of 17,000 kgf / cm ² or less. Since such a stainless sintered body is easily deformed by compression, it is possible to increase the diameter. Even if the diameter is increased, the tightening pressure is 100 kg.
The / cm ^2, a variant it is possible to obtain uniform contact with the electrolyte membrane 2, said clamping is no risk of cracking due to pressure because of the flexibility.

When the cathode power supply plate 4 becomes large and a large amount of hydrogen gas is generated, the cathode power supply plate 4 is formed on the anode power supply plate 3 in order to facilitate the flow of the gas and the permeated water and to make the temperature in the cell uniform. It is more preferable to form a groove (not shown) similar to that on the surface of the cathode power supply plate 4 opposite to the electrolyte membrane.

The thickness of the anode power feeding plate 3 and the cathode power feeding plate 4 is
Although not particularly limited, it is preferably 2 to 3 mm in use, and in this case, the groove 18 preferably has a depth of 1 to 1.5 mm, a width of 2 to 3 mm, and a groove interval of 2 to 3 mm.

The casing ring 16 fitted on the outer peripheral surface of the anode power feed plate 3 is, as shown in FIGS. 2, 3 and 5,
A peripheral groove 19 having a depth similar to that of the groove 18 is formed on the inner peripheral surface so as to communicate with the groove 18, and the ports 13, 1
Three through-holes 16a, 16 at positions corresponding to 4, 15
b and 16c are drilled. These through holes 16a-1
Of the 6c, through holes 16a and 16b and through holes 20 and 21 are provided between the peripheral groove 19 and the through holes 16a and 16b, respectively. A seat portion 23 for receiving the packing 22 is formed on the surface of the casing ring 16 that is not in contact with the electrolyte membrane 2.

As shown in FIGS. 4 and 6, the casing ring 17 fitted on the outer peripheral surface of the cathode power supply plate 4 has a peripheral groove 24, a seat portion 25 for receiving the packing 22 ', and a ring portion 25, as shown in FIGS. Through holes 17a, 17b, and 17c are formed, and among these, a through hole 26 that communicates both of them is formed only between the through hole 17c and the circumferential groove 24.

The packings 22, 22 'also have ports 13,
Holes 22a, 22b, 22c at positions corresponding to 14 and 15
Are formed. The casing rings 16 and 17 can be formed of a plastic material such as polysulfone or PTFE.

When assembling the cells thus constructed by stacking them, the cells are separated from each other and the anode chamber in which the anode power feeding plate 3 is housed and the cathode chamber in which the cathode power feeding plate 4 is housed are separated. Separating plate 6 has adjacent cells 5 and 5
In other words, it is arranged between the surface of the anode power supply plate 3 opposite to the electrolyte membrane 2 and the surface of the cathode power supply plate 4 opposite to the electrolyte membrane.

The separating plate 6 has a structure in which two single plates each having a thickness of about 0.5 to 1 mm are stacked, and the single plate 6a on the side in contact with the anode power feeding plate 3 is formed of a titanium plate, and the cathode power feeding is performed. The single plate 6b on the side contacting the plate 4 is formed of a stainless plate. This superposed separating plate replaces the bipolar plate with a considerable thickness grooved in the conventional bipolar multi-layer cell, so that a cell with a thickness of several tens to several tens is achieved as a whole. can do. Further, with this configuration, it is possible to impart corrosion resistance to a strong acid generated on the anode side and prevent hydrogen embrittlement due to hydrogen gas generated on the cathode side (titanium is easily hydrogen embrittlement). The separating plate 6 has through holes 6c, 6d, 6e at positions corresponding to the ports 13, 14, 15.

The separating plate 6 has packings 22, 2 from both sides.
By abutting 2 ', the leak between the cathode side and the anode side is sealed. Through holes 6c, 6d, 6 of the separating plate 6
A spacer ring 27 is fitted in e.

The cells 5 ... 5 thus constructed are
Through holes 2a to 2c, 16a to 16c, 17a to 17c,
Passages 28 and 2 that are stacked so that the holes 22a to 22c and the through holes 6c to 6e are aligned and communicate with the first to third ports.
9, 30 are formed. Pure water for electrolysis is supplied to the first port 13 from a water tank (not shown), and the pure water passes through the passage 2
8 through the through hole 20 of the ring 16 and the anode power feeding plate 3
Flows into the groove 18 of. Since the anode power feed plate 3 is formed of a sintered body of metal fibers having a high porosity, pure water reaches the electrolyte membrane 2 through the voids in the sintered body.

When a voltage is applied to the power feed plates 8a and 8b, only hydrogen ions in pure water in contact with the anode power feed plate 3 pass through the electrolyte membrane 2 to receive electrons from the cathode power feed plate 4 and hydrogen gas. And goes up in the cathode power feeding plate 4 formed of the stainless fiber sintered body, passes through the through hole 26, and passes through the passage 30.
And is discharged from the third port 15 via. The discharged hydrogen gas may be recovered by a known recovery means, if necessary, and may be released into the atmosphere when it is unnecessary, such as when the device is used as an ozone generator.

On the other hand, on the anode side, hydroxyl ions release electrons to generate oxygen gas and water, and these oxygen gas and water are mixed with the supplied pure water and pass through the voids in the titanium fiber sintered body. Then, it enters the passage 29 through the through hole 21 and is discharged from the second port 14. The second port 14 is connected to a water tank (not shown) so that pure water can be circulated.

Since the titanium fiber sintered body and the stainless fiber sintered body forming the anode power feeding plate 2 and the cathode power feeding plate 3 are hard to be broken even if they are thinned, the thickness thereof is set to 2.5 mm and the thickness of the separating plate 6 is set. Is 0.5 to 1 mm, the thickness per cell can be suppressed to about 7 mm, which is about 1/4 to 1/5 as compared with the conventional one.

[0035]

As described above, in the solid polymer electrolyte water electrolysis apparatus and the electrode structure thereof according to the present invention, the cathode power supply plate is formed of the conductive porous structure having the compression elastic modulus of 17,000 kgf / cm ² or less. Therefore, it is possible to realize a practical water electrolysis device in which the size and weight of the power supply plate are increased, the life of the membrane is increased, and the efficiency of electrolysis of ozone is increased.

Further, the cathode power supply plate is formed of a stainless fiber sintered body and / or a stainless steel sintered body having a groove on one side, and the anode power supply plate is formed of a titanium fiber sintered body, and the cathode side is stainless and the anode side is By using the separation plate made of titanium, the above effect can be further exerted.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a solid polymer electrolyte water electrolysis apparatus.

FIG. 2 is an exploded perspective view of a main part of the apparatus shown in FIG.

3 is a cross-sectional view along the plane A of the device shown in FIG.

4 is a cross-sectional view taken along the plane B of the device shown in FIG.

5 is a view showing an anode power supply plate and a ring fitted therein, which appears in a cross section taken along line CC of FIG.

FIG. 6 is a view showing a cathode power supply plate and a ring fitted therein, which appears in a cross section taken along the line D-D in FIG.

[Explanation of symbols]

 1 Solid polymer electrolyte water electrolysis device. 2 Polymer Electrolyte Membrane 3 Anode Power Supply Plate 4 Cathode Power Supply Plate 6 Separation Plate 18 Groove

Claims (7)

[Claims] 1. In a bipolar solid polymer electrolyte water electrolysis apparatus using a polymer electrolyte membrane as a solid electrolyte, the cathode power supply plate pressed against the cathode side of the polymer electrolyte membrane has a compression elastic modulus of 17,000 kgf / cm ^2. A solid polymer electrolyte water electrolyzer characterized by being formed of the following conductive porous structure. 2. A gas passage generated on a surface of the anode power feed plate opposite to the electrolyte membrane, the anode power feed plate being pressed against the anode side of the polymer electrolyte membrane is formed of a porous conductive material. The solid polymer electrolyte water electrolysis apparatus according to claim 1, wherein a groove is formed. 3. The solid polymer electrolyte water electrolysis apparatus according to claim 1, wherein the cathode power supply plate has parallel grooves formed on the surface opposite to the electrolyte membrane. 4. A separation plate for separating each cell is constructed by stacking a stainless plate and a titanium plate, and the stainless plate is arranged on the side of the separation plate which is in contact with the cathode power supply plate. The solid polymer electrolyte water electrolysis apparatus according to any one of claims 1 to 3. 5. The solid polymer electrolyte water electrolysis apparatus according to claim 1, wherein the anode power feeding plate is formed of a titanium fiber sintered body. 6. An electrode structure for a bipolar solid polymer electrolyte water electrolysis device using a polymer electrolyte membrane as a solid electrolyte, wherein a cathode power supply plate is formed of a sintered body of stainless fiber. An electrode structure characterized by the above. 7. The electrode structure of a solid polymer electrolyte water electrolyzer according to claim 6, wherein parallel grooves are formed on a surface of the cathode power supply plate opposite to the electrolyte membrane.