JPS60180059A - Silver (ii) oxide battery - Google Patents

Abstract

PURPOSE:To suppress film resistance when the film is immersed in an electrolyte and improve the storage performance of a secondary battery by laminating a polyethylene semi-transparent film in which an acrylic acid and such are graft- polymerized with the cellophane that forms a separator. CONSTITUTION:A polyethylene semi-transparent film 3 obtained by graft-polymerizing an acrylic or meta-acrylic acid is laminated between the cellophane layers 4 of a separator that makes contact with a positive electrode black mix 1 primarily made of silver (II) oxide. As a result, the separator whose film resistance exceeds 1,000mOMEGA-cm<2> when the film is immersed in a 30-50% caustic alkaline solution at 15-30 deg.C is formed. This protection laminate can provide a silver (II) oxide battery in which the functions of the separator are improved and the storage performance is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the storage performance of a silver oxide battery.

In recent years, with the spread of small M-band electronic devices, silver oxide batteries have become widely used as small, large-capacity batteries, and the positive electrode mixture has a discharge capacity per unit volume of 2
It is becoming common to use 0-40% larger silver oxide. However, batteries that use ferric oxide as the positive electrode mixture experience voltage failure within 60 to 100 days compared to silver oxide batteries stored under the same conditions, for example at a temperature of 60°C. In this case, the result was that the product could be stored for only 2 to 3 years, which is far from the 3 to 5 years required for practical use. When we disassembled the defective batteries as described above, we found that all the separators were severely damaged and were caused by internal short circuits, but this was limited to batteries that used ferric oxide as the positive electrode mixture; I couldn't find it. This is because ferric oxide has a stronger oxidizing power than silver oxide, and the seta plate that makes up the separator is oxidized.
This was due to the loss of its function as a separator. For this reason, oxidation-resistant and alkali-resistant polyethylene is used for the separator, and the grafting rate is low on the side close to the positive electrode mixture to make it difficult for silver oxide ions to pass through, and on the side close to the negative electrode mixture, ion exchange is performed. In order to improve properties and water retention, attempts have been made to increase the grafting rate and sequentially stack layers. However, as described above, the method of laminating polyethylene membranes with different grafting rates to form a separator has the disadvantage that the lamination process is complicated and storage performance varies depending on the grafting rate and the concentration and temperature of the electrolyte. was there.

In order to solve the above-mentioned drawbacks, the present invention protects cellophane with an oxidation-resistant and alkali-resistant film so that it can utilize its function as a separator, and controls the film resistance when immersed in a predetermined electrolytic solution, thereby achieving storage performance. This will be explained in detail below with reference to Examples.

FIG. 1 is a cross-sectional view of a silver oxide battery according to an embodiment of the present invention, in which 1 is a positive electrode mixture consisting of a mixture of second oxidation chain coarse particles and fine particles or powdered silver oxide; 2 is a positive electrode terminal; 3, which also serves as a positive electrode, has an electrical resistance of 1000 mΩ-Cn when immersed in a 40% caustic potash solution at a temperature of 15 to 30°C. As described above, a polyethylene semipermeable membrane obtained by graft polymerizing acrylic acid or methacrylic acid, etc. to polyethylene, such as Permion, a polyethylene graft membrane manufactured by Ray Research in the United States, can be used to obtain a predetermined membrane resistance. It is used by laminating multiple sheets.

4 is a layer of cellophane; 1 is, for example, PUD manufactured by DuPont in the United States;
One or two sheets of O195 or PUDO134 or the like are laminated and used. 5 is a layer for holding an alkaline electrolyte made of a non-woven fabric, 6 is a negative electrode mixture made of zinc as an active material and the electrolyte, 7 is a negative electrode container which also serves as a negative electrode terminal, and 8 is a synthetic resin gasket.

Next, in order to compare the storage characteristics of the batteries of the present invention with the above-described structure and conventional batteries, 10 batteries each were fabricated with different polyethylene semi-permeable membrane layers and cellophane layers. The number of voltage failures was investigated after one day of storage (approximately 3 circuits when stored at 25°C) and after 100 days (approximately 5 years when stored at 25°C), and the results are shown in Table 1. The test battery is TR916W, with a diameter of 9.41Ellφ and a total height of 1.6
In B, caustic potash was used as the electrolyte. In addition, the polyethylene semi-permeable membrane is Permion P manufactured by Ray Research Co., Ltd. in the United States.
-229140/60 and PUDO193 manufactured by DuPont, USA were used as the cellophane.

Table 1 In Table 1, 0) and (b) are conventional batteries, and (f) are batteries of the present invention. From Table 1, conventional batteries &), (I:9
After storage at 60"C for 60 days, most of the cellophane in A2 was oxidized and disappeared, 8 out of 10 items in (e) were defective, and 2 out of 10 items in (b) were defective. The difference in the number of defective pieces in 0) and (b) is due to the presence or absence of A49 seven openings and handles, and while in (a) all of the pieces were defective after 100 days of storage at 60°C, (
(b) Only 7 out of 10 were defective. This becomes even clearer when comparing (b) and (c). That is, simply replacing A4 cellophane with P-2291 increases the number of defective pieces after storage at 60'C for 100 days.

Next) is when A3 is used as cellophane, 60℃, 60℃
No defects occurred after storage for 60'C, 10 days.
After storage for 0 days, half of the batteries were defective, and the battery of the present invention
When cellophane is used on A4 paper, no defects occur even after storage at 60°C for 100 days. In addition, when cellophane is not used as in (e), 4 out of 10 pieces become defective after being stored at 60°C for 60 days. (G) is a battery using silver oxide as the positive electrode mixture, and no defects occurred even after storage at 60° C. for 100 days.

A more detailed analysis of the above results shows that the membrane resistance of the polyethylene semi-permeable membrane on the side of the seven-parator near the positive electrode is 1.
It can be seen that the storage performance can be improved if the layers are stacked so that the resistance is 1 [100 ffiΩ-cr& or more when immersed in a 30-50% caustic potassium solution at 5°C to 30°C, and cellophane is placed on the side closer to the negative electrode. .

As described above, the present invention uses polyethylene semi-permeable membranes of the same type to be laminated and cellophane is placed thereon to form a separator, so that it can be manufactured in a simple process and has stable storage performance. can be provided, and its industrial value is great.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a silver oxide battery according to the present invention. 1... Positive electrode mixture 6... Negative electrode mixture 3...Lamination of polyethylene semi-permeable membrane 4...cellophane layer 5...Nonwoven fabric for electrolyte retention Applicant Yuasa Battery Co., Ltd. Figure 1

Claims (1)

[Claims] A polyethylene semi-permeable membrane obtained by graft polymerization of acrylic acid or methacrylic acid is placed between the positive electrode mixture mainly composed of silver oxide and the septhanum which forms part of the heplayer.
A ferric oxide battery characterized in that it is laminated to form a separator so that the membrane resistance becomes 1000 mΩ-c4 or more when immersed in a 30 to 50% caustic potassium solution at a temperature of 15 to 30°C.