JPS5810378A - Manufacture of air cell - Google Patents

Abstract

PURPOSE:To prevent electrolyte from intruding into a border between a catalytic layer and a water repelling film by eliminating the trouble of liquid leakage caused by contamination of a case which occurs when a paste-like catalyst is inserted into the case, and solidifying the contact face between said water repelling film and positive catalytic layer. CONSTITUTION:A porous air diffusion paper 3 mainly consisting of cellulose is placed on the bottom of an anode case 1 having an air supplying hole 2, a porous fluorine resin film 4 is placed thereon and further a nickel net 6 is inserted into the anode case 1 to be put on the fluorine resin film 4. A fixed quantity of catalyst 5 cured in paste-like form is injected onto the nickel net 6 with an injection cylinder 10 to be heated and dried. Through said process the trouble of adhesion of active carbon powder to an inside wall 8 of the anode case 1 can be dissolved, thus preventing electrolyte from intruding into the border part between the catalytic layer 5 and the water repelling film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a catalyst layer for oxygen activation of a button type air battery, and eliminates leakage caused by contamination of the case when inserting a paste catalyst into the case. At the same time, the purpose is to prevent the electrolyte from entering the boundary between the catalyst layer and the water-repellent film by strengthening the contact between the water-repellent film and the positive electrode catalyst layer.

Button-type air batteries have a small internal volume (the cathode volume for the R44 type is approximately 0.2 cc), which contains a negative electrode active material.
- Since it is necessary to fill as much as possible, it is necessary to make the positive electrode catalyst layer as thin as possible.

To explain this with reference to FIG. 1, an air diffusion paper 3 is placed on the bottom of a positive electrode case 1 in which air supply holes 2 are pre-drilled, and a fluororesin film 4 punched to the same diameter as the inner diameter of the case is placed on top of the air diffusion paper 3, and a positive electrode The catalyst layers 5 are placed in order. In addition to this, the positive electrode catalyst layer 5 was manufactured by the following method.

That is, activated carbon, which is the main component, acetylene plaque, which is a conductive material, and some water-repellent binder are kneaded into a paste with water, and then applied to the metal core material 6 with two rolls.
It was filled under pressure. This method is the most common method for manufacturing thin electrodes.

The catalyst layer 5 manufactured by this method is punched out to have the same diameter as the inner diameter of the positive electrode case 1 in the same way as the water-repellent film 4, and is overlapped with the water-repellent film 4.
Insert into positive electrode case 1.

At this time, the punched cut portion 7 of the metal core material 6 of the catalyst layer 5 must come into contact with the inner wall 8 of the positive electrode case 1 (37). When configuring a button type air battery,
Since the electrical contact between the positive electrode case 1 and the positive electrode catalyst layer 6 is only through the cut portion 7 of the metal core material 6, the punched positive electrode catalyst layer 5 must have the same inner diameter as the positive electrode case 1.

However, the positive electrode catalyst layer 6 has the same diameter as the inner diameter of the positive electrode case 1.
Since its main component is activated carbon, activated carbon powder is attached to the cut portion 7, and when inserted into the positive electrode case 1, the activated carbon powder adheres to the inner wall 8 of the case 1.

Activated carbon powder adhering to the inner wall 8 of the positive electrode case 1 was undesirable because it induced leakage when the button type air cell was constructed.

1. The catalyst layer 6 punched out to have the same diameter as the inner diameter of the positive electrode case 1 is water repellent to the positive electrode catalyst layer 5, as shown in the cross section of FIG. 2 (enlarged view of section A in FIG. 1). Gap 9 at the boundary with membrane 4
This caused the electrolytic solution to enter the gap 9 during battery construction and wet the catalyst layer 6, reducing the activity of the catalyst layer 6, making it impossible to obtain good results in terms of battery performance.

Gap 9 at the boundary between the positive electrode catalyst layer 6 and the fluororesin water-repellent film 4
It is thought that this occurs due to various factors. One of the reasons for this is that the positive electrode case 1 and the catalyst layer 5 must be electrically connected at the cut portion 7 of the core metal 6 of the catalyst layer 5. Punch it out to be the same as the inner diameter or slightly larger, and insert it into the positive electrode case 1. Next, in order to ensure contact between the positive electrode case 1 and the cut portion 7 of the core material 6, it is necessary to press the peripheral portion of the positive electrode catalyst layer 6.

At that time, the positive electrode catalyst layer 6 may partially protrude slightly toward the center of the case 1, and a gap 9 is generated at the boundary between the positive electrode catalyst layer 5 and the water-repellent film 4.

Moreover, suppressing the entire positive electrode catalyst layer 6 means that the porosity is 30
This has the disadvantage that the pores of the 7-polymer resin water-repellent membrane 4, which is 50% porous, are crushed, and the original purpose of the clear water membrane 40 is lost.

In order to solve the drawbacks mentioned in the conventional example, the present inventors conducted an experimental study on the following method and were able to reach a favorable conclusion6.

Hereinafter, the present invention will be explained with reference to FIG. 3. A porous air diffusion paper 3 mainly made of cellulose and having a thickness of 0.3 to 0.4 mm is placed on the bottom of a positive electrode case 1 having air supply holes 2. On top of that, there is a porous material punched out with the same diameter as the inner diameter of case 1.
．． A fluororesin film 4 having a thickness of 2 to Q, 25+mn is placed.

Finally, 0, 2-0, 3+ with 60-100 meshes
A nickel net 6 with a thickness of o+ is punched out to have the same diameter as the fluororesin film 4, and inserted into the positive electrode case 1, and the fluororesin film 4 is inserted into the positive electrode case 1.
Overlap with. During this overlapping, the nickel net 6 must be in complete contact with the inner wall 8 of the positive electrode case 1 at its cut portion 7.

The catalyst layer 5 includes 100 parts by weight of activated carbon, 10 parts by weight of acetylene black, and polytetrafluoroethylene (PTFE).
20 parts by weight of desversion and 300 parts by weight of water were thoroughly kneaded and the viscosity was adjusted to 3000-5000 cps.

A fixed amount of the catalyst 6 prepared in the form of a paste is injected onto the Nisokernet 1-6 using an injection cylinder 10. The amount of paste catalyst 5 injected at this time also determines the thickness and weight of the catalyst layer 5 when the battery is completed, so the amount of injection must be adjusted to the required amount depending on the size of the air cell, etc.

The paste catalyst 6 injected onto the nickel net 6 is
It spreads on the fluororesin film 4 with the nickel net 6 interposed, and then the water is evaporated at 60° to 8°.
Heat and dry in a dryer at 0°C for about 2 hours.

The catalyst layer 6 dried in the positive electrode case 1 in the above steps is
As shown in the sectional view of FIG. 4, it is pressurized to a certain size by a pressurizing mold 11. The best thickness for button-type air batteries after this pressurization is about 0.2 to 0.3 fins.

By adopting the above-described manufacturing process for the positive electrode catalyst layer 6 of a button-type air cell, it is possible to solve the conventional problem of adhesion of activated carbon powder to the inner wall 8 of the positive electrode case 1, which causes liquid leakage, and to repel fluororesin. Since the contact between the water film 4 and the positive electrode catalyst layer 5 is perfect 7 - without any gaps 9, it is possible to prevent the electrolyte from entering the boundary between the catalyst layer 5 and the water-repellent film 4, and the catalyst layer The deterioration of catalyst activity caused by wetting with the electrolytic solution in No. 5 could be sufficiently prevented.

By employing the method of manufacturing the positive electrode catalyst layer of the present invention, it was possible to obtain the results shown in the following table regarding liquid leakage caused by adhesion of activated carbon to the inner wall of the case.

The test temperature was 46°C and the leakage rate was compared after storage for 20 days in a relative humidity of 90%.

In addition, because the adhesion between the catalyst layer and the water-repellent film has become perfect, the discharge performance has also been improved.
．． 4+mn), continuous discharge with a 180Q load was able to obtain the results shown in FIG. In the figure, a shows the characteristics of the conventional product, and b shows the characteristics of the product of the present invention.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the positive electrode assembly process of a conventional button-type air cell, FIG. 2 is an enlarged sectional view of section A in FIG. 4 is a cross-sectional view showing the positive electrode catalyst layer pressurizing step according to the present invention, and FIG. 6 is a diagram showing continuous discharge curves at I BOQ load of a conventional R44 type air battery and the same type air battery according to the present invention. It is. 1...Positive electrode case, 2...Air supply hole,
3... Air diffusion paper, 4... Water repellent film, 5...
... Paste catalyst, 6 ... Nickel net (metal current collector), 11 ... Pressure mold. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig. 2 Fig. 3 Fig. 2 Near Fig. 4 Fig. 5 Tribal conquest time (h)

Claims (1)

[Claims] A step of placing an air diffusion paper, a water-repellent film, and a metal current collector in order from the bottom into a positive electrode case having an air supply hole at the bottom;
A method for producing an air cell, comprising the steps of injecting a paste catalyst mainly composed of activated carbon into the metal current collector section, and drying and pressurizing the paste catalyst layer.