JPS6041763A - Air electrode and its manufacture - Google Patents

Abstract

PURPOSE:To stabilize the discharge characteristic of an air cell by providing a fluorine resin coat layer between a catalyst layer and a water repellent film and providing a resin adhesive layer between the catalyst layer and a separator. CONSTITUTION:A fluorine resin coat layer 11 is formed between a water repellent film 4 and a catalyst layer 5-1 containing a fluorine resin and catalyst particles. A resin adhesive layer 2 is formed between a catalyst layer 5-1 and a separator 6. The fluorine resin coat layer 11 is recommended to be formed by applying an aqueous tetrafluoroethylene dispersion, an aqueous tetrafluoroethylene-hexafluoropropylene copolymer dispersion, a compound such as vinylidene fluoride or its mixture solution by brush painting, spray painting or a similar method in such a manner that 0.1-15mg/cm<2> of the solid component is fixed. For the adhesive layer 12, a resin adhesive having an adhesive effect even under dry conditions and moistened conditions is preferred to an aqueous adhesive.

Description

[Detailed description of the invention] Not for industrial use! 11f.

Invention U:, button type air battery 1 yen f: 5j No I air? This article relates to ν spirit used in Ij/ya, etc., and its manufacturing method.

Structure of conventional examples and their problems Conventionally, button) glJlfHp air cells are manufactured as follows. Thoroughly knead with a john to form a base, apply this to a metal screen and dry it IA'!, then apply porous fluorine 1 to the 11th surface (adhere to the old finger membrane and air) if < J: I,
, within the tangent case? , an electric electrode and a separator were incorporated, and a zinc negative electrode and a 7/l/J) IJ electrolyte were incorporated into the plate, and after coupling, the battery was sealed and completed.

In this case, the reason why an aqueous dispersion of fluororesin is mixed into the catalyst particles is to maintain water repellency so that oxygen can easily diffuse into the catalyst since oxygen in the air is used as a positive electrode active material. be.

The reason why the catalyst and the water-repellent film are brought into close contact is to prevent the alkaline electrolyte that has passed through the catalyst from accumulating on the air-side surface or leaking out of the battery.

"Just press the catalyst and the water-repellent film together," L7 Kashina said.
Since the adhesion strength is weak, this adhesion interface quickly peels off partially, causing the electrolyte to stagnate and inhibit oxygen diffusion, resulting in deterioration of the battery's discharge characteristics.

Therefore, we decided to provide a coating layer of an aqueous dispersion of fluororesin on the surface of the catalyst. Nagisa et al. previously proposed a measure to strengthen the adhesion between the catalyst and the water-repellent film.

Indeed, this measure improved the adhesion strength at the interface between the catalyst and the water-repellent film, and stabilized the battery characteristics. However, as an air electrode, this alone is not necessarily sufficient.
However, there are some problems such as the following. At the time of sealing the air battery, air rises between the electrolytic wave of the catalyst and the separator, which causes the electric current to the catalyst to rise.
The problem is that the supply of Il/1' liquid is insufficient, which lowers the reaction efficiency of the catalyst, causing a decrease in the internal resistance of the battery and the weight of the battery.

The reason why air is trapped between the catalyst and the separator is that when the battery is sealed, the bottom of the first ring moves towards the middle/0 part of the seal, and the separator also moves towards the middle/U part. This is thought to be because the separator moves and the separator swells.

Purpose of the present invention is to strengthen the adhesion strength between the catalyst layer and the water-repellent membrane constituting the air electrode, and at the same time completely prevent the air flY1 from twisting between the catalyst layer and the separator. The purpose is to stabilize the discharge characteristics of.

Structure of the Invention In order to achieve the above object, the present invention provides a coating layer of a fluororesin between a catalyst layer containing a fluororesin and catalyst particles and a water-repellent film, and a coating layer of a fluororesin is provided between the catalyst layer and the separator. It is characterized by being provided with a resin adhesive layer.

A resin adhesive layer is provided between the catalyst layer and the separator by applying a water-soluble adhesive to a nonwoven fabric, as shown in Japanese Patent Application Laid-Open No. 57-172665'rj. However, in this case, since the space between the catalyst and the separator is dry during battery sealing 1-1, water-soluble JJ? The adhesive does not exhibit any adhesive effect. Further, even if the catalyst and separator are in close contact with each other after the battery is sealed, this alone is not sufficient as an air electrode. Again, the catalyst layer is medium/U 2, and the air is diffused on one side 1. It has strong water repellency and tightly adheres to the water repellent film, and the other side of the catalyst layer has a strong bond with the separator.
It is necessary to finish in the 4th division.

Example 1 is a fluororesin coating layer at the interface between the catalyst layer and the water-repellent film.
．． 47) An aqueous dispersion of ethylene fluoride, an aqueous dispersion of a combination of tetrafluoroethylene and propylene fluoride, or 11'1 such as vinylitine fluoride.
It is recommended that the solid content be 0.1 to 15 parts/(゛J) by coating or 7-ply coating on the catalyst surface. In this case, oxygen cannot diffuse, so it is better to be porous.
Although it is best to disperse the material in bulk, 47) ethylene is the worst option since it tends to be porous and has strong water repellency.

Also, this fluorine 4r#I fat cloth layer is only on the catalyst side;
It is also possible to apply it to the water-repellent film side without 1.

On the other hand, for the adhesive layer between the separator and the catalyst, a resin material that has a contacting effect both when dry and wet is better than a water-soluble adhesive.

It is the w7 combination of water-soluble J'2 jsF agent, -OH, -C
It has a large number of hydrophilic groups such as OOH, and after forming an electrode, it is oxidized by the positive electrode in the battery, or decomposed by the IQQ liquid, losing its adhesive effect, and at the same time remains in the battery as an impurity. However, this is not preferable because it tends to deteriorate battery characteristics. However, in the case of resin adhesives, only hydrophilic groups are required! It is stable even in electrolyte, and
It also does not undergo oxidation from the positive electrode.

Examples of this resin adhesive include polyethylene, polypropylene, and chlorosulfonated polyethylene.

These include thermoplastic resins such as ethylene acrylic acid copolymer and polyamide resin represented by nylon, thermosetting resins such as epoxy, and mixed resins of polyamide and epoxy, and mixtures of multiple of these resins are possible. be.

Now, regarding the present invention, the following means are more effective.

That is, a fluororesin coating layer is provided on both sides of a catalyst layer containing a fluororesin, and a water-repellent film is adhered to one side, and a separator is adhered to the other side via a resin adhesive.

By doing so, the adhesive strength between the separator and the catalyst is further strengthened, the battery characteristics are stabilized, and the storage capacity of the battery is improved.

The presence of the fluororesin cloth layer on the catalyst surface on the separator side (electrolyte side) strengthens the water repellency of the catalyst surface and makes it less compatible with the I'l'r liquid. However, if there is a resin adhesive layer between the separator and the separator, this is not necessarily the case.
li: Also stabilizes the compatibility of Ih' liquid.

The reason for the strong adhesion is that the catalyst layer originally consists of i-i' catalyst particles, which are hardened with fluororesin fibers, but since there are catalyst particles, the binding strength is not sufficient. . Unfortunately, even if an adhesive layer was present between the separator catalysts, the catalyst particles were separated, and the adhesive strength could not be sufficiently strengthened with a small amount of adhesive 41i. However, in the case of having a fluororesin coating layer, the fluorine in the fluororesin cloth layer and the catalyst layer also combine with the fat.
At the same time as increasing the strength of the catalyst layer, the catalyst surface becomes fluorine (6) with no catalyst particles. This fluororesin surface and resin adhesive adhere well, and there is no partial looseness. Therefore, it is possible to exhibit a stable and strong adhesive effect.

The method of applying fluororesin to the catalyst may be the above-mentioned dip coating or spray coating method, but in the case of double-sided coating of the catalyst, the catalyst is immersed in an aqueous dispersion of fluororesin. It's easy and good.

In addition, the coating layer of resin adhesive is applied to the separator or catalyst surface by spray coating or bubbling.
As shown in FIGS. 1A and 1B, the electrolytic solution is made to exist in spots or intermittently, so that the electrolytic solution can easily penetrate into the catalyst through the separator. In FIG. 1, 6il''j is a separator, and 12 is a dotted adhesive.

The weight of this adhesive is approximately 0.01 to 1.00"
I/oJ is unreasonable.

In addition, when an adhesive layer is provided, a resin surface porous membrane has a higher adhesive strength as a separator.

Therefore, it is more preferable to use a nonwoven fabric containing 4 g of liquid in combination with Mj) a greasy pore membrane.

Description of Examples (Example 1) As a catalyst, manganese oxide, activated carbon, and carbon black were each mixed in a proportion of 220 and 50.10 parts by weight, respectively. Parts by weight were added, thoroughly kneaded, and coated on a nickel screen in the form of a sheet to obtain a 4n thick catalyst sheet. This Kakumushi plot/-1・Nobayama I
K HoIJ Apply an aqueous dispersion of tetrafluoroethylene 2, dry, and rinse (after treatment, the amount of coating is approximately 1.0
mfl/t:r7, thickness o, 2π
A water-repellent film made of porous 4-fluorinated ethylene was pressure-bonded.

Then, on one side of the separator, spray 0.2 M1/ctl of polyamide amine-epoxy mixture II diluted with toluene.
It was in a dotted state showing 8A'/43';ilt L-. After this was brought into close contact with the catalyst, it was heat-treated and bonded at 1QO''. The cross-sectional structure of the air electrode thus obtained is shown in Figure 2. Punch it out and pressure test it.

Ta. 4 in the figure is water repellent 1, 6-1 +-1: IQ! II medium layer, 5-21j: current collector, 6- separator, 11-fluororesin coating layer, 12 is adhesive layer. Using this ll-, pole, the outer diameter is 11.6 mm and the height is 5 as shown in Figure 3.
．． I made a 4-tone button type air battery.

This battery is made as follows. 1, 4 city case 1
The air diffusion paper 3 is put in the above-mentioned 1-1, the water-repellent film 4 is fixed with a fluororesin, the separator 6 is adhered to the other side with an adhesive layer, and the positive electrode 5 is put in.

On the other hand, an alkaline electrolyte consisting of a zinc negative electrode 9 and an aqueous potassium hydroxide solution is put into the sealing plate 7 combined with the sealing ring 8,
After coupling with the positive electrode case, the battery is sealed with I-1. Note that in 10, the sky at the positive pole is A.

(Example 2) Using the same catalyst as in Example 1, this catalyst was immersed in an aqueous dispersion of polytetrafluoroethylene, and after dry heat treatment, the (I'M amount of polytetrafluoroethylene was about 2. ○tsu/C gong seven ゛ru'' Niunishi, Ta.

Thereafter, in exactly the same manner as in Example 1, the water-repellent film was pressure-bonded and the separator was bonded.

The cross-sectional structure of the air electrode thus obtained is shown in FIG. This has a diameter of 11. A positive electrode was punched out at ○am. In the figure, 4 is a water-repellent film, 5-1-1 catalyst layer, 6-2ii current collector, 6I/:↓ separator, 11-horn resin cloth layer, and 12&:j:l adhesive layer. Using this positive electrode, a Botanos τ air battery of the same size as in Example 1 was formed,
Mark this as B.

□ As a comparative example, a button-shaped air cell of the same size as Examples 1 and 2 was produced using the same catalyst as in Example 1.2, constructing an air electrode without a fluororesin coating layer and a resin adhesive layer. -・Ta. Let this be C.

Using these batteries A, B, and C, immediately after manufacture and at 60°
Internal resistance after storing 10011 in C and 25 in 20”
The discharge maintenance 7L pressure after 2011 old HJ with 0Ω load was compared. The results are shown in the table below.

From this table, it is clear that the electric current of the present invention is 111xA.

Compared to the conventional comparative example C, the internal resistance of B is small and stable immediately after manufacturing, and the σ value is small.

After preservation, it is further expressed in K1.

The voltage maintained after 20 hours with a 20" (130Ω load) is stable from immediately after manufacture to after storage.3゜However, even within the present invention, B is better than A. The internal resistance is small but stable, and the voltage maintained after storage is high.

From these facts, it is clear that the water-repellent film and the separator are strengthened by the fluororesin layer and the resin adhesive coating layer according to the present invention, and the separator is The fluorocarbon resin is also used on the catalyst surface towards the
It is more effective to provide the j layer.

Incidentally, as the adhesive, a polyamitoamine-epoxy mixed resin is used in the examples described in AfJ, but as described in the main text, it exhibits the same effectiveness as a thermoplastic resin or a thermosetting resin.

Furthermore, the present invention can be widely applied not only to button-type air batteries but also to all types of batteries that utilize air electrodes, such as cylindrical, stationary, and box-type batteries.

Effects of the Invention As described above, by using the air electrode according to the present invention, the internal resistance of the air battery can be stabilized and the storage characteristics can be improved.

[Brief explanation of the drawing]

Figures 1A and B are diagrams showing the dispersion state of the adhesive on the separator, Figure 2 is a cross-sectional view of the air electrode, which is the 11-electrode in Example 1 of the present invention, and Figure 3 is the same positive electrode. FIG. 4 is a cross-sectional view of an air electrode, which is a positive electrode, in Example 2 of the present invention. 1...Positive electrode case, 2...Air hole, 3...
Air diffusion paper, 4... Water repellent film, 6... Positive electrode, 5
-1... Catalyst layer, 6-2... Current collector, 6
Separate layer, 11--Fluororesin coating layer, 12--Mi'l fat adhesive layer.

Claims (6)

[Claims] (1) A structure in which a water-repellent film is in close contact with one side of the catalyst layer containing a fluororesin and catalyst particles, and a separator is in close contact with the other side, and An air electrode characterized by having a fluororesin coating layer between the water film and a resin adhesive layer between the catalyst layer and the separator. (2) The catalyst layer has a fluorine J, J, J resin coating layer on both sides, and a resin adhesive layer is provided between the fluororesin coating layer on one side of the catalyst layer and the separator (claim 1) Air electrode as described. (3) The air electrode according to claim 1 or 2, wherein the resin adhesive layer is scattered or intermittent in parts. (4) The resin adhesive layer is a thermoplastic resin or thermosetting resin! #"j R'+The air electrode according to any one of claims 1 to 3. (5) A method for producing an air electrode, which comprises forming a fluorine frrJ fat coating layer on the surface of a catalyst layer containing a fluororesin and catalyst particles, and coating or dipping an aqueous dispersion of fluorine & I fat. (6) The claimed manufacturing method, in which the fluororesin coating layer is formed by spraying or bubbling an aqueous fluororesin dispersion.