JPH0533498B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for preserving a positive electrode mixture for a silver oxide battery. Conventional structure and problems Conventionally, in manufacturing silver oxide batteries, the main component of the positive electrode is silver oxide, which is mixed with manganese dioxide, graphite, etc., and this positive electrode mixture is filled into the positive electrode case. The mixture was then pressed into close contact with the inner surface of the case. However, it has become clear that this positive electrode mixture, which is pressure-molded inside the case, adsorbs carbon dioxide gas when stored in the air, which has a significant negative effect on the storage characteristics of silver oxide batteries. In order to minimize the adsorption of carbon dioxide gas, it was considered that (a) mass production and storage in a vacuum, and (b) positive electrodes molded on the same day were assembled into batteries and used up on the same day. If a battery is assembled using stored materials immediately, there will be no problem with the characteristics of the battery, but the storage vacuum chamber should be kept in a vacuum state to store the mixture, return to atmospheric pressure, take out the mixture, and then The remaining mixture must be stored under vacuum again. It was found that by repeating this process, it becomes easier to adsorb carbon dioxide gas in the positive electrode mixture, and that more carbon dioxide gas is adsorbed than when stored in the atmosphere. In the latter case, productivity is significantly lower. Therefore,
Strict conditions were required to manufacture silver oxide batteries with stable quality. Purpose of the Invention The purpose of the present invention is to manufacture a battery that is suitable for mass production and has stable quality by storing a molded positive electrode of a silver oxide battery in a tray and storing the entire tray in a sealed manner. It is. Structure of the Invention That is, in order to achieve the above object, a molded positive electrode of a silver oxide battery is housed in a tray, and the entire tray is covered with a gas-impermeable resin film and stored in a sealed manner, thereby eliminating air pollution during storage. It is characterized by cutting off contact with carbon dioxide gas and allowing it to be taken out and used at any time during production. DESCRIPTION OF EMBODIMENTS Below, as an example of the present invention, a diameter of 11.6 mm and a height of
A 5.4mm button-type silver oxide battery will be explained. In Fig. 1, 1 is a positive electrode case, and 2 is a positive electrode mixture consisting mainly of silver oxide, which is a positive electrode active material, mixed with manganese dioxide and graphite.This is temporarily molded and placed in case 1. put the mixture into the positive electrode ring 3
It is also pressed into close contact with the inside of the case 1.
4 is a separator, 5 is a liquid-containing material, 6 is a sealing plate, and a nylon ring 7 is coupled to the periphery thereof. 8 is a negative electrode active material made of zinc. The electrolyte used was 10 moles of KOH saturated with zinc oxide. Next, a method for preserving the positive electrode of the present invention will be described. The positive electrode mixture is first molded, and then case 1 is formed together with ring 3.
After being inserted into the case, a fixed number of molded mixtures (referred to as positive electrode half cells) 9 that are tightly pressed to the case are stored in a resin tray container 10, and the entire tray is made of polyethylene, polyvinylidene chloride, nylon, or vinylon. It is wrapped with any gas-impermeable film 11 such as, for example, and the adhesive portion 12 is completely sealed as shown in FIG. 2 by heat fusion or ultrasonic fusion. FIG. 3 is a sectional view taken along the line -' in FIG. 2. When using a molded mixture, cover film 1
1 and take out the required number of half-cells 9 and assemble them into a battery. The remaining half-cell 9 may be completely sealed again with the resin film 11. In addition to film, it may be sealed with a bag with a check, but since the inflow of air cannot be completely stopped, it is most preferable to heat-seal the film. Figure 4 shows the changes in open circuit voltage of battery A constructed using a positive electrode half cell stored in the atmosphere and battery B constructed using a molded mixture according to the present invention that was stored in a hermetically sealed manner, as a function of the number of days the mixture was stored. It is shown by the relationship. Note that the voltage here indicates a value measured 16 hours after battery assembly. As a result, the method of storing positive electrode half cells in the atmosphere showed that the open circuit voltage decreased with the number of storage days.
In particular, the decrease up to the 5th day is remarkable. No abnormalities were observed even after 15 days in the sealed samples. In addition, the positive electrode half cell was stored for 10 days to form a battery, and the battery was subjected to a storage test at 60°C. As a result, no abnormality was observed in the open circuit voltage in case B even after 100 days had passed as shown in the following table, but in case A there was a decrease in open circuit voltage from 60 days onwards. Similarly, internal resistance also showed an upward trend compared to the initial stage.

[Table] When the battery with the voltage drop was disassembled, the separator was severely discolored and an internal shoot had occurred. Also, in the manufacturing process, by sealing a large number of positive electrode half cells at once, it is suitable for mass production. Effects of the Invention By storing the molded positive electrode mixture in a hermetically sealed manner as described above, it is not affected by carbon dioxide gas due to storage, thereby making mass production possible and providing a battery with stable characteristics. In addition, the same effect was obtained by sealing the molded positive electrode mixture without a tray, but the case became dirty, causing leakage defects, and problems with the appearance of the product, and the product was stored in a tray. This was an excellent method in terms of quality and process.

[Brief explanation of the drawing]

Figure 1 is a half-sectional view of a button-type silver oxide battery, Figure 2
The figure is a partial top view of the same battery stored in a tray container and sealed, Figure 3 is a cross-sectional view taken along the -' line in Figure 2, and Figure 4 is the relationship between the storage period of the positive electrode mixture and the open circuit voltage. It is a figure showing a relationship. 1... Positive electrode case, 2... Positive electrode mixture, 3... Positive electrode ring, 4... Separator, 5... Liquid-containing material, 6
... sealing plate, 7 ... nylon ring, 8 ... negative electrode active material, 9 ... positive electrode half cell, 10 ... tray container, 11 ... sealing resin film.

Claims (1)

[Scope of Claims] 1. A positive electrode mixture containing silver oxide as a main component is filled into a positive electrode case, and the molded mixture in which the positive electrode mixture and the case are brought into close contact with each other under pressure is stored in a tray container. A method for preserving a positive electrode of a silver oxide battery, which is characterized by storing the entire cathode in a gas-impermeable resin film. 2. The silver oxide according to claim 1, in which a tray containing a molded positive electrode mixture and a gas-impermeable resin film that covers the entire tray are sealed by heat fusion or ultrasonic fusion. How to store battery positive electrodes.