JPS6063880A - Zinc air battery - Google Patents

Abstract

PURPOSE:To increase utilization efficiency of inner volume of a battery and improve leakage resistance capability by inserting a water repellent film so as to contact the inside of a positive case having flat bottom, and placing a ring, a catalyst layer, and a separator on the water repallent film, and compressing their peripheries. CONSTITUTION:A water repellent film 10 is inserted so as to contact the inside bottom of a cylindrical positive case 2 having flat bottom in which an air hole 11 is installed, and a ring 13 is placed on its periphery. A catalyst layer 7 having a water repellent film 9 and a current collector 8, and a separator 6 which separates negative active material 3 are placed on the ring 13, and these peripheries are compressed by a gasket 4. The water repellent film 10 is formed by punching, for example, porous tetrafluoroethylene film having a porosity of 50- 80%, and is used to diffuse oxygen in the air which serves as positive active material and to prevent leakage from the air hole of the positive case.

Description

[Detailed description of the invention] Industrial applications The present invention relates to improvements in air batteries.

Conventional structure and problems Conventionally, in button-type air batteries, the catalyst layer of the positive electrode can be made thinner, so the filling volume of the negative electrode active material is large, compared to other alkaline battery systems. It has the feature of being able to supply large capacity batteries.

A typical structure of such an air battery, such as a zinc-air battery, is shown in Figure 1.

In Fig. 1, numeral 1 denotes a sealing plate which also serves as a negative electrode terminal, and a three-layer cladding material of nickel, stainless steel, and copper is used from the outer surface. 2 is a positive electrode case that also serves as a positive electrode terminal, and is made of iron plated with nickel. This positive electrode case has a stepped portion 2a at the bottom 9, and a diffusion paper 1o is housed inside the stepped portion 2a.

The purpose of this bottom step and the diffusion paper is to improve the diffusion of oxygen in the air, which is the positive electrode active material, into the catalyst layer, and to improve the diffusion of oxygen from the air, which is the positive electrode active material, into the catalyst layer, and to improve the diffusion of oxygen from the air, which is the positive electrode active material, into the catalyst layer. By pressing the peripheral edges of the two water-repellent films 9 onto the stepped portion, a sealed area is formed to prevent liquid from leaking from the positive electrode case air hole 11.

However, this configuration has the following problems due to the fact that the positive electrode case 2 has the stepped portion 2a.

That is, (1) the volume utilization rate to take advantage of the large capacity, which is a feature of air batteries, deteriorates.

(2) Because the moldability of the positive electrode case is poor, the dimensional accuracy of the positive electrode case is poor and there are large variations in the stepped parts.
Leak resistance, especially leakage from the positive electrode case air hole.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an air battery that eliminates the above-mentioned drawbacks of the conventional examples, has high efficiency in the use of battery internal volume, and has excellent leakage resistance.

Structure of the Invention The present invention includes inserting a water-repellent film so as to be in contact with the inner bottom of a cylindrical positive electrode case having a flat bottom with air holes,
An annular ring is placed above the periphery, and a separator is placed on the annular ring to separate the catalyst layer having a water-repellent film and a current collector, and the negative electrode active material, and these peripheries are compressed and fastened using gas care. It is.

According to this configuration, by eliminating the stepped portion of the positive electrode case, which is a conventional problem, it is possible to improve the utilization efficiency of the battery internal volume. Furthermore, it is possible to obtain a positive electrode case with stable dimensional accuracy, and the water-repellent film inserted so as to be in contact with the inner bottom of the positive electrode case during sealing is sufficiently crimped to the inner bottom of the positive electrode case, resulting in a good sealing area. This makes it possible to suppress liquid leakage from the positive electrode case air hole.

DESCRIPTION OF EMBODIMENTS Next, embodiments of the present invention will be described using a PR44 type zinc-air battery.

FIG. 2 is a half-sectional view of a PR44 type battery according to the present invention. In the figure, 1 is a three-layer cladding phase of nickel-stainless steel-copper with a thickness of 0.3Qffg and an outer diameter of 10.5ff.
It is a sealing plate with a height of 4.2 mm and is punched out to have a U-shaped folded part on the periphery. 2 is a steel plate with a thickness of 0.3QMH, an outer diameter of 11.6mm, and a height of 5.0gm.
This is a cylindrical positive electrode case that is punched out, has air holes 11 with a diameter of 0.5*m, and is then plated with nickel. 3
is a kneaded product consisting of zinc oxide powder having a freezing rate of 10Φ, which is a negative electrode active material, and an alkaline electrolyte, and is filled into the inside of the assembly of the sealing ring 4 made of polyamide resin and the sealing plate 1. 6 is an impregnating material made of cotton nonwoven fabric, and 6 is a separator.

The positive electrode catalyst layer 7 is made of γ-type electrolytic manganese dioxide at 360°C.
30 parts by weight of activated carbon, 20 parts by weight of acetylene black, and 30 parts by weight of an aqueous dispersion of ethyne tetrafluoride with a hard cedar content of 60 wt% are mixed with 30 parts by weight of β-type manganese dioxide by heat treatment. This was made into a paste, coated with nickel screen 8, made into a sheet with a thickness of 0.6 mm, and after drying to remove water, it was punched out to a diameter of 11.0 mm, with pores of 0.3 mm thick on one side. A water-repellent film 9 made of a porous tetrafluoroethylene film with a 20% ratio and a separator 6 made of cross-linked polyethylene with a thickness of 0.10 m* are adhered to the other side.

13 is an annular ring made of polyvinyl chloride, and has an outer diameter of 11.0 mm, an inner diameter of 10.6 mm, and a thickness of 0.20 mm. By optimizing the thickness of this annular ring based on the battery size, etc., it becomes possible to increase the utilization efficiency of the battery internal volume. The material of this annular ring may be either alkali-resistant synthetic resin or metal.

10. It is a water-repellent membrane inserted so as to be in contact with the inner bottom of the case, which is a feature of the present invention. It is a porous tetrafluoroethylene membrane with a thickness of 0.30 mm and a porosity of 60%, and a diameter of 11.0 mm. *It is punched out and has the purpose of improving oxygen diffusion.

Furthermore, the water-repellent film 10 also has the effect of improving leakage resistance from the air holes 11 of the positive electrode case 2.

That is, in the conventional example, when sealing, two water-repellent films that are in close contact with the lower part of the catalyst layer are pressed onto the stepped portion to form a sealed region. However, this sealing region obviously has poor leakage resistance because it largely depends on the dimensional accuracy in molding the positive electrode case, such as the flatness of the stepped portion and the height of the stepped portion.

However, in this embodiment, the front water-repellent film is sufficiently pressed against the inner bottom of the flat and rough positive electrode case during sealing, so that a stable and good sealing area is formed. Therefore, it has improved and more stable leakage resistance than the conventional example. The following table shows a comparison of discharge capacity and leakage resistance, with the battery of this example as a human battery and the battery of the conventional example as B.

Note that the discharge capacity was calculated from the product of the discharge time and discharge sustaining voltage of the discharge curve at 20'Q and 620Ω. Further, liquid leakage was determined by visually observing the liquid leakage state from the air hole 11 of the positive electrode case after leaving it for 1 to 10 weeks with the seal paper 12 removed for a predetermined period in a humid environment at 45°C and 990%.

As is clear from the table, the battery of this example is superior to conventional example B in terms of discharge capacity and leakage resistance.

Next, the water-repellent film that is in contact with the inner bottom of the positive electrode case, which is a feature of the present invention, will be described. A feature of the present invention is that the water-repellent film includes:
The purpose of the conventional diffusion paper is to achieve the effect of promoting the diffusion of oxygen in the air, which is the positive electrode active material, and to prevent liquid leakage from the air holes of the positive electrode case. As a result, it has become possible to remove the diffusion paper present in the conventional example.

In order to effectively diffuse oxygen in the air, the porosity of the water-repellent film is an important factor, and as a result of various trial productions with different porosity, we have found that the porosity is between 60 and 80%. The characteristics of the battery using the water-repellent film were good.

When the porosity was less than 60%, oxygen was not sufficiently diffused, and when it was more than 80%, the leakage performance deteriorated.

On the other hand, suppression of liquid leakage from the positive electrode case air holes is further improved by providing a continuous sealing region made of a sealant between the lower peripheral edge of the water-repellent film and the inner bottom of the positive electrode case. As the sealant, thermoplastic resins such as polybutene, polyamide resin, pinch, asphalt, and chlorosulfonated polyethylene may be used. These sealants form a more intimate sealing area when the water-repellent film is pressed against the inner bottom of the positive electrode case during sealing, and exhibit a remarkable effect in suppressing liquid leakage from the positive electrode case air holes.

Also, applying a sealant around the annular ring,
It has a remarkable effect on suppressing liquid leakage.

Effects of the Invention As can be seen from the above embodiments, a water-repellent film is inserted so as to be in contact with the inside of the positive electrode case having a flat bottom, and a catalyst layer having an annular ring, a water-repellent film, and a current collector is placed on top of the water-repellent film. An air battery having a structure in which a separator is arranged to isolate the negative electrode active material and the periphery of the separator is compressed and fastened has good leakage resistance and a large discharge capacity.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view of a conventional air battery, and FIG. 2 is a half-sectional view of an air battery according to an embodiment of the present invention. 1 is a sealing plate, 2 is a positive electrode case, 3 is a negative electrode active material, 4 is a sealing ring, 5 is an impregnating material, 6 is a separator, 7 is a positive electrode catalyst layer,
8 is a core material, 9 and 10 are water-repellent films, 11 is an air hole, 12 is a sticker paper, and 13 is an annular ring.

Claims (1)

[Claims] This is an air battery that uses a cylindrical positive electrode case that has a flat bottom with air holes and that also serves as a positive terminal.A water-repellent film is inserted so as to be in contact with the inner bottom of the positive electrode case, and an annular ring is placed on the upper edge of the water-repellent film. A positive electrode catalyst layer having a water-repellent film and a current collector and a separator for separating the negative electrode active material are arranged in order on the annular ring, and a negative electrode case containing the negative electrode active material and the positive electrode are arranged in order. An air cell characterized in that the peripheries of the water-repellent film, the positive electrode catalyst layer, and the separator are compressed and fastened by a gasket that isolates the case.