JP3100754B2 - Method for manufacturing electrochemical device using solid polymer electrolyte membrane - Google Patents

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 an electrochemical device using a solid polymer electrolyte membrane used for a fuel cell, an electric field tank, a gas sensor and the like.

[0002]

2. Description of the Related Art Electrochemical devices in which an electrode catalyst layer is attached to a solid polymer electrolyte membrane are widely used in fuel cells, electric field tanks and the like. And in such an electrochemical device, various manufacturing methods have been proposed in order to increase the utilization rate of the electrode catalyst layer. For example, in Japanese Patent Publication No. 2-4987, the surface of the solid polymer electrolyte membrane is roughened using an abrasive or the like, and the electrode catalyst layer is fixed to this portion to form a solid polymer electrolyte membrane. The reaction interface between the electrode catalyst layer and the electrode catalyst layer is three-dimensionally enlarged, thereby increasing the use efficiency of the electrode catalyst layer.

[0003] Further, in Japanese Patent Application Laid-Open No. Hei 3-167752, the surface of an electrode catalyst layer is made uneven by a press jig, and the electrode catalyst layer is brought into close contact with a solid polymer electrolyte membrane. The reaction interface between the solid polymer electrolyte membrane and the electrode catalyst layer is three-dimensionally enlarged, thereby increasing the use efficiency of the electrode catalyst layer.

[0004]

However, in each of the above-mentioned conventional electrochemical devices, when the solid polymer electrolyte membrane absorbs moisture and expands significantly, the solid polymer electrolyte membrane and the electrode catalyst layer become three-dimensional. There is a problem that the dimensional reaction interface is physically separated and easily separated. For this reason,
In such an electrochemical device, a considerable surface is always present between the solid polymer electrolyte membrane and the electrode catalyst layer regardless of the operation of the electrochemical device so that the solid polymer electrolyte membrane does not expand even if it absorbs moisture. It needed to be under pressure.
In addition, all of the above-mentioned electrochemical devices require a roughening step, and the manufacturing operation thereof is not easy.

The present invention has been made in order to solve the above-mentioned problems, and a special operation is performed on a three-dimensional reaction interface formed between a solid polymer electrolyte membrane and an electrode catalyst layer. It is an object of the present invention to provide a method of manufacturing an electrochemical device using a solid polymer electrolyte membrane that can be maintained without performing and easy to manufacture.

[0006]

Means for Solving the Problems The method of manufacturing an electrochemical device using the solid polymer electrolyte membrane according to this inventions are ionic solid high having a sulfonic acid group as the ion exchange group to sandwich the electrode catalyst layer Larger than molecular electrolyte membrane and electrode catalyst layer
Crisp and has a smaller area than solid polymer electrolyte membrane
That with the electrode substrate and hot-pressed at a temperature of lower than 130 ° C. or higher 210 ° C., the surface of the electrode substrate to supply the Ru was bite to more depth 30μm solid polymer electrolyte in membrane electrode
It is characterized in that the entire base material is cut into the solid polymer electrolyte membrane .

[0007]

[0008]

In the present invention, the temperature of the hot press is set to 13
The reason why the temperature is set to 0 ° C. or higher and lower than 210 ° C. is that the electrode base material can be cut into the solid polymer electrolyte membrane with a small surface pressure without causing thermal decomposition of the solid polymer electrolyte membrane. Also, larger than the electrode catalyst layer, and solid high content
Was allowed bites to over a thickness of 30μm to a surface of the conductive Gokumoto material having a smaller area than the child electrolyte membrane solid polymer electrolyte in membrane, solid polymer electrolyte membrane hygroscopic to inflated electrode substrate be Is to prevent a part from coming off or falling off from the solid polymer electrolyte membrane side, and to form a three-dimensional reaction interface between the solid polymer electrolyte membrane and the electrode catalyst layer. . In addition, solid polymer electrolysis
The solid polymer electrolysis of the electrode substrate
This is to further prevent detachment or falling off from the membrane side.

[0009]

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. Embodiment 1 FIG. FIG. 1 is a side view of members constituting a solid polymer electrolyte type electrode before hot pressing, showing an embodiment according to the first invention of the present invention, and FIG. 2 is a solid polymer electrolyte formed by hot pressing. It is a sectional side view of a pattern electrode.

In the figure, 1 is a solid polymer electrolyte membrane that allows ions to pass but does not allow electrons to pass through, 2 is a thin electrode catalyst layer having a thickness of 50 μm or less, and 3 is a porous membrane that is harder than the solid polymer electrolyte membrane 1 at a predetermined temperature. The electrode substrate 4 made of a conductive material having many pores or gaps is formed by sandwiching a solid polymer electrolyte membrane 1 having an electrode catalyst layer 2 on both surfaces thereof between a pair of electrode substrates 3 and 3. This is a solid polymer electrolyte type electrode as an electrochemical device in which the electrode substrate 3 is pressed into the solid polymer electrolyte membrane 1 to a depth of 30 μm or more.

Here, those which can be used as the solid polymer electrolyte membrane 1 have a sulfonic acid group as an ion exchange group.
An ionic solid polymer electrolyte membrane , for example, EI Dupont de Num
ours & Co) to Nafion
Or a sulfonated perfluorocarbon membrane sold under the trade name of Dow Chemical
l Co. There are similar membranes available from). In addition, what can be used as the electrode catalyst layer 2 includes a dispersion of platinum black fine particles and a polytetrafluoroethylene resin, and a solution obtained by hydrolyzing a solid polymer electrolyte membrane and dissolving in a solvent containing isopropyl alcohol as a main component. Then 50μ
m or a thin film sheet prepared using a high surface area carbon powder carrying platinum fine particles instead of platinum black fine particles, or directly electrolessly plated on the solid polymer electrolyte membrane 1. Platinum particle layer or platinum particles physically attached to the solid polymer electrolyte membrane 1. Further, examples of the material usable as the electrode substrate 3 include porous carbon paper and an expanded metal plate made of platinum plated titanium. In addition, as shown in FIG.
The electrode substrate 3 has an area smaller than the solid polymer electrolyte membrane 1.
The electrode catalyst layer 2 is smaller than the electrode base material 3.
Those with a large area are used.

Next, the conditions for hot pressing will be described. First, general temperature and pressure conditions during hot pressing will be described. The solid polymer electrolyte membrane 1 generally has 13
Softens at a temperature of 0 ° C. or more and starts thermal decomposition at a temperature of 210 ° C. or more. Therefore, the temperature of the hot press is 130
A temperature of not less than 210 ° C and not less than 210 ° C is desirable. The solid polymer electrolyte membrane 1 has a pressure of 10 kgf /
Deforms easily with surface pressure of ² cm2 or more. Therefore, the pressure of the hot press is 10 kgf / cm ² or more. In the case of using the carbon paper as the electrode substrate 3, because there is a possibility that carbon fiber is cut at 100 kgf / cm ² or more surface pressure, the maximum pressure of the hot pressing is less than 100 kg / cm ² Although preferred, when the expanded metal plate is used as the electrode substrate 3, there is no such limitation.

Next, the depth of penetration of the surface of the electrode substrate 3 into the solid polymer electrolyte membrane 1 during hot pressing will be described with reference to specific examples. In this case, Nafion 117 was used as the solid polymer electrolyte membrane 1. The carbon paper having a thickness of 0.1 mm was used as the electrode base material 3 and hot-pressed under the conditions of a temperature of 170 ° C. and a pressure of 50 kgf / cm ² so that the carbon paper had a penetration depth of 7 mm.
When the thickness reaches 0 μm, even if the solid polymer electrolyte type electrode 4 formed by hot pressing is left in water for two days and nights, the solid polymer electrolyte membrane 1 expands and detaches or falls off the carbon paper. In addition, the function of the solid polymer electrolyte electrode 4 as an electrochemical device is maintained.

When the expanded metal plate is used as the electrode substrate 3, the bite depth can be further increased at the same temperature and pressure as compared with the above case. However, the temperature is lowered and the expanded metal plate is hot-pressed. When the solid polymer electrolyte type electrode 4 is bitten by 30 μm or more, even if the solid polymer electrolyte membrane 1 absorbs moisture, the expanded metal plate does not come off or fall off, and the expanded metal plate electrode substrate 3 There was no hindrance to the current collection function.

On the other hand, regardless of whether carbon paper or expanded metal plate is used as the electrode substrate 3, if the penetration depth into the solid polymer electrolyte membrane 1 is less than 30 μm, the solid polymer If the electrolyte membrane 1 absorbs moisture and expands, there is a strong possibility that the electrode base material 3 may be partially removed from the solid polymer electrolyte membrane 1 or fall off.

From other various experimental results, the depth of penetration of the electrode substrate 3 into the solid polymer electrolyte membrane 1 depends not only on the temperature and pressure conditions during hot pressing, but also on the composition and thickness of the electrode catalyst layer 2. It was also found that the electrode base material 3 changed depending on the material and shape of the electrode base material 3, the type of the solid polymer electrolyte membrane 1, and the like. It has been found that it is desirable that the depth of penetration of the electrode substrate 3 into the solid polymer electrolyte membrane 1 be 30 μm or more in order to prevent the above.

Next, a state around the electrode catalyst layer 2 when the electrode base material 3 is hot pressed under the above conditions and the electrode base material 3 digs into the solid polymer electrolyte membrane 1 by 30 μm or more will be described. When the cross section of the electrode catalyst layer 2 of the solid polymer electrolyte type electrode 4 is observed with a scanning electron microscope, as shown in FIG. 2, the reaction interface between the electrode catalyst layer 2 and the solid polymer electrolyte membrane 1 is three-dimensional. It can be seen that they are formed in

That is, at the time of hot pressing, the solid polymer electrolyte membrane 1 tries to enter the hole of the electrode substrate 3.
Due to the movement of the solid polymer electrolyte membrane 1 trying to penetrate into the hole of the electrode base material 3, the electrode catalyst layer 2 disposed between the solid polymer electrolyte membrane 1 and the electrode base material 3 is extended and The hole 3 of the material 3 penetrates as a mountain-shaped or polyp-shaped projection (only the cross section looks like a bellows shape as shown in FIG. 2). At the same time, the solid polymer electrolyte membrane 1 also penetrates into the hole of the electrode substrate 3 to the inner side of the protrusion of the electrode catalyst layer 2, and the reaction interface between the electrode catalyst layer 2 and the solid polymer electrolyte membrane 1 is three-dimensional. This reaction interface is enlarged compared to a planar one. Therefore, in the solid polymer electrolyte type electrode 4, the utilization rate of the electrode catalyst layer 2 can be increased, and the solid polymer electrolyte type electrode 4 is used as a small, high-performance electrochemical device.

Embodiment 2 FIG. In Example 1, hot pressing was performed so that the surface of the electrode substrate 3 was cut into the solid polymer electrolyte membrane 1 at a depth of 30 μm or more at a temperature of 130 ° C. to 210 ° C. While keeping these conditions as they were, the entire electrode substrate 3 was cut into the solid polymer electrolyte membrane 1 so as to be completely embedded therein. This further prevents the electrode substrate 3 from falling off from the solid polymer electrolyte membrane 1. However, in this case, if the electrode substrates 3 on both sides come into contact with each other, the function as an electrochemical device is lost.

In Examples 1 and 2, the electrode catalyst layer 2 and the electrode base material 3 were provided on both sides of the solid polymer electrolyte membrane 1.
Has been described, but the electrode catalyst layer 2 is formed only on one side of the solid polymer electrolyte membrane 1.
The present invention can also be applied to an electrochemical device in which the electrode device 3 and the electrode substrate 3 bite.

[0022]

The inventions As is apparent from the above description, according to the present invention
According to the ionic solid polymer electrolyte membrane having a sulfonic acid group across the electrode catalyst layer as an ion-exchange group, electrode
Larger than the catalyst layer and smaller than the solid polymer electrolyte membrane
And hot pressing the electrode substrate having had the area at a temperature below 130 ° C. or higher 210 ° C., Ru was bite into the surface of the electrode substrate to 30μm or more depth to the solid polymer electrolyte in film
In addition, the entire electrode substrate is cut into the solid polymer electrolyte membrane.
Since Mase, the three-dimensional test the reaction interface can be formed between the solid polymer electrolyte membrane and the electrode catalyst layer can be maintained without the the reaction interface special operation. Also, it is a process of roughened to an electrochemical device of the traditional is unnecessary,
The manufacturing operation of the electrochemical device using the solid polymer electrolyte membrane can be facilitated.

[0023]

[Brief description of the drawings]

FIG. 1 is a side view of members constituting a solid polymer electrolyte type electrode before hot pressing according to Embodiment 1 of the present invention.

FIG. 2 is a side sectional view of a solid polymer electrolyte type electrode according to Embodiment 1 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Solid polymer electrolyte membrane 2 Electrode catalyst layer 3 Electrode substrate 4 Solid polymer electrolyte type electrode (electrochemical device)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-126774 (JP, A) JP-A-62-196389 (JP, A) JP-A-58-126675 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01M 8/00-8/24

Claims (1)

(57) [Claims] 1. The method according to claim 1, wherein the sulfonic acid group is ion
An ionic solid polymer electrolyte membrane having an exchange group ,
Larger than the electrode catalyst layer, and the solid polymer electrolysis
An electrode substrate having an area less than Shitsumaku hot pressed at a temperature of lower than 130 ° C. or higher 210 ° C., Ru was bite into the surface of the electrode substrate to the solid polymer electrolyte 30μm or more depths in the membrane With the whole electrode substrate,
A method for manufacturing an electrochemical device using a solid polymer electrolyte membrane, characterized in that the electrochemical device is cut into a solid polymer electrolyte membrane.