JP2000328279A - Production of power feeding body for electrochemical cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process for producing a power feeding body for an electrochemical cell which is prolonged in the life without damaging electrolyte electrode joint and capable of keeping a desirable state of electricity, gas and water flow over a long period therein. SOLUTION: The manufacturing procedure of the power feeding body for electrochemical cell comprises, at first, manufacturing a sintered body of titanium powder having outside dimension equal to or larger than the predetermined outer dimension of the power feeding body and having a thickness larger than the predetermined thickness of the power feeding body by compressing, molding and sintering the titanium powder 1, and manufacturing the plural power feeding bodies having the predetermined thicknesses and outside dimensions by slicing the thick sintered body of the titanium powder. Further, the slicing is made to be the flattening slicing, for instance, wire discharging processing, processing with a diamond band saw so that a abutting face between the power feeding body and the electrolyte electrode joint becomes to be the smoothing surface required for the performance and the life of the electrochemical cell simultaneously with the slicing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water electrolysis cell for producing hydrogen and oxygen using a solid polymer electrolyte membrane,
Conversely, the present invention relates to a method of manufacturing a power supply for an electrochemical cell used for an electrochemical cell such as a fuel cell that takes out electricity by an electrochemical reaction between hydrogen and oxygen.

[0002]

2. Description of the Related Art In recent years, a water electrolysis cell for producing hydrogen and oxygen using a solid polymer electrolyte membrane (Japanese Patent Laid-Open No. 7-2526).
No. 82), and conversely, the development and commercialization of a solid polymer electrolyte fuel cell that extracts electricity by an electrochemical reaction between hydrogen and oxygen. Electrochemical cells such as the above-mentioned water electrolysis cell and fuel cell form a unit by contacting a power feeder to both main surfaces of an electrolyte electrode assembly formed by bonding an electrode catalyst layer to both surfaces of a solid polymer electrolyte membrane, A configuration in which a number of these units are stacked and main electrodes are provided at both ends thereof is generally used. In some cases, a configuration in which an electrode catalyst layer is joined to the surface of a power supply body may be used. For convenience of explanation, the following description will be made with reference to a power supply for a water electrolysis cell, but the present invention is also applicable to a power supply for a fuel cell.

[0003] In the above-mentioned water electrolysis cell, a power feeder disposed in contact with the electrolyte electrode assembly is required to have a function of supplying electricity, supplying water, and quickly discharging gas generated by the water electrolysis reaction. .

[0004] For this reason, initially, a feeder using an expanded metal of titanium, a perforated metal plate, a mesh plate, or the like was used, but all of them had a very large opening, and the feeder and the electrolyte electrode were used. When the joined body was pressed into contact with the joined body, there was a problem that the electrolyte electrode joined body having a relatively small thickness (approximately 50 μm) sunk into the opening, and the electrolyte electrode joined body was easily damaged. For this reason, for example, as described in Japanese Patent Publication No. 2-32357, a titanium fiber having a large particle diameter is compressed, molded, and sintered to produce a substrate, and then a titanium powder having a small particle diameter is formed on the surface thereof. compression,
A power feeder has been developed in which the surface in contact with the electrolyte electrode assembly is formed into a fine structure by forming and sintering into a unitary structure, and has a smooth structure as compared with the surface of the titanium fiber layer.

FIG. 3 is a diagram schematically showing a cross section in the layer direction of the conventional power supply for an electrochemical cell. This feeder is
It is constituted as a titanium powder sintered plate of a predetermined size composed of a titanium fiber 12 having a large particle diameter on the lower layer side and a titanium powder 11 having a small particle diameter on the upper layer side, and the surface of the titanium powder 11 is applied to the electrolyte electrode assembly. Used as a contact surface.

[0006]

However, the above-described conventional method for manufacturing a power supply for an electrochemical cell has the following problems.

[0007] The titanium powder sintered plate is prepared by placing titanium powder in a mold and compressing the plate to form a plate-shaped compact having substantially the same dimensions as a predetermined size of the power supply body. It has been produced. In this case, due to the deformation that occurs when the material is taken out of the mold and transferred to a vacuum sintering furnace and the shrinkage that occurs during sintering (the surface side shrinks), the sintered plate warps (curves), and the surface that contacts the electrolyte electrode assembly It is difficult to obtain a suitable surface shape and surface state.

[0008] When the electrode catalyst layers on both sides of the electrolyte electrode assembly are pressed against such a titanium powder sintered plate, a uniform contact state cannot be obtained, and electricity cannot be supplied uniformly. However, there has been a problem that an excessively large force is locally applied, and the electrolyte electrode assembly is damaged and the life is shortened.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to improve the life of the electrolyte electrode assembly without causing damage to the assembly, and to reduce the electricity, gas and water. An object of the present invention is to provide a method for manufacturing a power supply for an electrochemical cell, which can maintain a good flow for a long time.

[0010]

In order to solve the above-mentioned problems, the present invention relates to a method in which a power feeder is applied to both main surfaces of an electrolyte electrode assembly in which an electrode catalyst layer is bonded to both surfaces of a solid polymer electrolyte membrane. In the method of manufacturing a power supply for an electrochemical cell having a large number of units stacked and main electrodes provided at both ends thereof, a titanium powder is compressed, molded, and sintered to form a unit. A titanium powder sintered body having an outer dimension equal to or larger than the predetermined outer dimension (same or slightly larger) and having a thickness dimension larger than the predetermined thickness dimension of the power supply body is produced. Slicing titanium powder sintered body,
A plurality of feeders having a predetermined thickness dimension and an outer dimension are manufactured, and the slicing process is such that, at the same time as the slicing, the contact surface of the feeder with the electrolyte electrode assembly is formed of the electrochemical cell. The flattening slicing is performed so as to obtain a desired smooth surface with high performance and life (claim 1).

The flattening slicing is preferably performed by wire electric discharge machining or diamond band saw machining. As a result, the electrolyte electrode assembly does not bite between the titanium powder particles. In addition, since a flat contact surface without warpage is obtained, the contact of the power feeder with the electrolyte electrode assembly is uniform, so that an excessive force is not locally applied, and the electrolyte electrode assembly is not damaged. Since the flow of electricity is better,
The service life of the electrolyte electrode assembly is improved, and high efficiency as an electrochemical cell can be maintained. Furthermore, by flattening slicing, a plurality of feeders of a predetermined size can be produced from the thick titanium powder sintered body almost simultaneously by slicing, so that manufacturing efficiency can be improved and costs can be reduced.

Further, as in the third aspect of the present invention, it is preferable that after the contact surface is flattened, the contact surface is further polished. Adhesion of the power supply to the electrolyte electrode assembly becomes more uniform, and the efficiency as an electrochemical cell is further improved.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

(Example) FIG. 1 is a diagram schematically showing a cross section in a layer direction of a power supply for an electrochemical cell manufactured by a manufacturing method of the present invention, and FIG. 2 is a diagram showing compression of titanium powder according to an example of the present invention.
The schematic block diagram of the cold isostatic press used for manufacture of the titanium powder compact by shaping | molding is shown. First, as shown in FIG.
The rubber case 3 filled with the titanium powder 1 was placed in the pressure vessel 4, and pressurized water 6 was supplied into the pressure vessel 4 by the pressurizing pump 5 to produce a compression molded body of the titanium powder 1.

The filled titanium powder 1 has a particle size of 100 to
Water pressure was set to 2000 kg / cm ² using 150 μm.
Hold for 0 minutes.

Next, the produced compact 7 is placed in a vacuum sintering furnace and sintered at 1000 ° C. for 1 hour in a vacuum.
A titanium powder sintered body having a diameter of 100 mm and a length of 100 mm was obtained. Next, this titanium powder sintered body was sliced into a predetermined thickness (about 1 mm) by a wire electric discharge machine to obtain a disk-shaped power supply having a diameter of 100 mm and predetermined dimensions. Note that the end surface of the sintered body having a length of 100 mm is not in an expected surface state, and is appropriately cut and removed.

The conditions of wire discharge pressurization were as follows: a brass wire having a diameter of 0.2 mm was used at a voltage of 40 V and a feed rate of 4 mm / min. As shown in FIG. 1, the cross section in the layer direction of the power feeder was in a state where titanium powder was dispersed substantially uniformly, and when the surface shape was examined, the difference between the center plane and the end was 3 μm. It was concave and the surface roughness was 1 μm, and a desired smooth surface was obtained. When the feeder of this example was applied to a water electrolysis cell using a solid polymer electrolyte membrane having an electrode area of 50 cm ² , there was no damage to the membrane electrode assembly due to long-term operation, and no reduction in efficiency was observed.

(Comparative Example) A sintered titanium powder plate manufactured by a conventional manufacturing method has the same dimensions (diameter 10
0 mmφ, thickness 1 mm), the height difference between the central surface and the end of the surface was 30 μm, and the surface roughness was 15 μm. When this conventional feeder using titanium powder is applied to a water electrolysis cell using a solid polymer electrolyte membrane having an electrode area of 50 cm ² , damage to the membrane electrode assembly gradually progresses, and
After running for 000 hours, a decrease in current efficiency of about 3% due to leakage current was observed.

As described above, the reason why the current efficiency does not decrease when the power supply according to the embodiment of the present invention is applied is that the power supply is cut straight by the wire electric discharge machine, so that the electrolyte electrode assembly of the power supply is used. It is considered that there was no warpage of the contact surface, and the protrusion of the titanium powder was cut smoothly, and the adhesion of the power supply body to the electrolyte electrode assembly became more uniform. Further, by using various polishing methods such as lap polishing to further smooth the cut surface of the wire electric discharge machining, the efficiency can be further improved.

In the embodiment, the slicing of the titanium powder sintered plate is performed by a wire electric discharge machine, but a diamond band saw or the like can be used as another slicing machine. In the case of a band saw other than diamond, fine streaks are formed on the machined surface, so that the performance is slightly inferior to wire electric discharge machining or diamond band saw machining. Also, in the case of disk processing, a slight blur occurs on the disk due to the stickiness of titanium,
Slight warpage or rough surface occurs on the contact surface, and the performance is further inferior.

[0021]

According to the present invention, as described above, in the method of manufacturing a power supply for an electrochemical cell, titanium powder is compressed, molded, and sintered to have the same external dimensions as the predetermined external dimensions of the power supply. And a titanium powder sintered body having a thickness dimension larger than a predetermined thickness dimension of the power supply body is produced, and the thick titanium powder sintered body is sliced to form a plurality of predetermined titanium powder sintered bodies. A feeder having a thickness dimension and an outer dimension is manufactured, and in the slicing, the contact surface of the feeder with the electrolyte electrode assembly is placed at the same time as the slicing on the performance and life of the electrochemical cell. The flattening slicing is performed by, for example, wire electric discharge machining or diamond band sawing so as to provide a smooth surface in the initial stage (Claims 1 and 2). Excessive force is added It is eliminated. Therefore, the electrolyte electrode assembly is not damaged, and the life of the electrolyte electrode assembly is improved. Further, since the flow of electricity becomes good, high efficiency as an electrochemical cell can be maintained.

Further, by flattening slice processing,
Since a plurality of feeders can be manufactured almost simultaneously, it is possible to improve the manufacturing efficiency and reduce the manufacturing cost. In principle, one sheet may be used, but the more sheets, the more efficient.

Further, as in the third aspect of the present invention, by further polishing the flattened sliced contact surface, the adhesion of the power supply to the electrolyte electrode assembly becomes more uniform, and as an electrochemical cell, Efficiency is further improved.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a cross section in a layer direction of a power supply body according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a titanium powder compression and molding press related to the method for manufacturing a power supply body of the present invention.

FIG. 3 is a diagram schematically showing a cross section in a layer direction of a power feeding body according to a conventional manufacturing method.

[Explanation of symbols]

1: titanium powder, 3: rubber case, 4: pressure vessel,
5: Pump for pressurization, 6: Pressure water.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01M 8/10 H01M 8/10 F term (Reference) 4K011 AA02 AA12 AA15 CA05 DA01 4K021 AA01 BA02 CA05 DB04 DB12 DB21 DB31 DB43 EA03 5H018 AA06 AS01 BB01 BB03 BB11 CC06 DD01 DD08 EE02 5H026 AA06 BB01 BB02 BB06 CX01 CX04 EE02

Claims (3)

[Claims] A unit is formed by contacting a power feeder to both main surfaces of an electrolyte electrode assembly in which an electrode catalyst layer is bonded to both surfaces of a solid polymer electrolyte membrane. In the method of manufacturing a power supply for an electrochemical cell having a main electrode, the titanium powder is compressed, molded, and sintered to have an external dimension equal to or greater than a predetermined external dimension of the power supply, and A titanium powder sintered body having a thickness dimension larger than a predetermined thickness dimension of the body is produced, and the titanium powder sintered body having this thickness is sliced to form a plurality of pieces having a predetermined thickness dimension and an outer dimension. And the slicing process is such that, at the same time as the slicing, the contact surface of the feeder with the electrolyte electrode assembly becomes a smooth surface with the expected performance and life of the electrochemical cell. It is characterized by flattening slice processing like this A method for manufacturing a power supply for an electrochemical cell. 2. The method according to claim 1, wherein the flattening slice processing is wire electric discharge machining or diamond band saw processing. 3. The method according to claim 1, wherein the flattened and sliced power supply body is further polished on a contact surface with the electrolyte electrode assembly. Manufacturing method of power supply for chemical cell.