JPS5851475A - Silver-dioxide battery - Google Patents

Abstract

PURPOSE:To increase the discharge capacity of an AgO battery, improve the moldability of the positive mixture, and suppress the decomposition of AgO caused during the preservation of the battery by using as a positive active material, AgO granules the surfaces of which are reduced into Ag2O. CONSTITUTION:After a granular AgO powder is made into granules with grain diameters of 50-500mu, the surfaces of the granules are reduced into Ag2O. Thus treated granules are used as a positive active material for a silver-oxide battery. By the means mentioned above, the electric potential of AgO can be extinguished with a smaller reducing power than that need when a granular AgO powder is used as the positive active material. As a result, the discharge capacity of the battery can be increased. Besides, the moldability of the positive active material can be improved by granulating the AgO powder. In addition, the decomposition of AgO caused during the preservation of the battery can be suppressed due to the reduced specific surface area of the positive active material.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is an improved method for producing a ferric oxide battery. The purpose is to improve discharge capacity, improve moldability, and suppress decomposition of ferric oxide during storage. In ferric oxide batteries, ferric oxide is used to prevent double discharge. It is necessary to erase the silver potential.

Therefore, attempts have been made to reduce the surface of the ferric oxide powder to ferric oxide or to add ferrous oxide powder to the ferric oxide powder. No.-
When reducing to silver, ferric oxide powder has a particle size of 0.1-10
Since it is a fine powder of about μm size and has a large specific surface area, it is necessary to reduce the amount of particles, which causes the problem of lowering the discharge capacity. When adding ferrous oxide, it is impossible to eliminate the potential of ferrous oxide without adding a large amount of ferrous oxide powder. In view of such circumstances, the present inventors conducted various studies, and as a result, When granulating ferric oxide powder into fist-like particles with a particle size of 660 to 600 a and reducing the surface of the ferric oxide particles to silver oxide and using this as a positive electrode active material, powdered oxide Using ferric silver, it is possible to erase the ferric oxide potential with a smaller amount of reduction than in the case of using ferric silver, thereby improving the discharge capacity, improving formability through granulation, and reducing the specific surface area. It was discovered that the decomposition of ferric oxide during battery storage could be suppressed, and the present invention was completed with only ◇ In order to make ferric oxide into granules in the present invention, for example, the particle size is 0.1 to 9. The process is carried out by making ordinary silver oxide powder of about 1 Q psm into a thriller form with water, granulating it with a granulator, preferably granulating it with a spherical granulator, and drying it.

The surface of the obtained second oxidized chain granules can be reduced to silver oxide by thermal decomposition in a nitrogen atmosphere or by reduction with ethyl alcohol or formaldehyde in an alkaline aqueous solution. The amount of return is 6~
It is preferable to set it to 20% (weight %, the same applies hereinafter). This is because if the reduction amount is too small, it will be difficult to erase the silver oxide potential, and if it is too large, the discharge capacity will decrease. Also, the particle size of the oxidized second chain granules should be adjusted to 50 to 50 mm. The reason for this is that when the particle size is smaller than 60μN1, the specific surface area increases and the amount of reduction increases.
This is because if it is larger than 00 am, there will be large variations in the filling amount and the moldability will be poor.

Figure 1 shows ferric oxide (Age) and silver oxide (AgzO).
) is a diagram showing the relationship between the composition ratio and the open circuit voltage. In FIG. 1, curve a is when oxidized second chain granules are reduced, curve C is when ferric oxide powder is reduced, and curve C is when oxidized second chain granules are reduced. shows the following case when ferric oxide powder and ferrous oxide powder are mixed. - The average particle size of the oxidized second chain granules in curve aK is 110
0p, the reduction is carried out by pyrolysis, and the curve bK
The average particle size of the ferric oxide powder is 5 pm, and the reduction was carried out by thermal decomposition in the same way as in the case of granules.Curve C shows the ferric oxide powder with an average particle size of 5 ppm. It is a mixture of powder and ferrous oxide powder with an average particle size of 6 PIR.

As is clear from the results shown in Figure 1, when reducing ferrous oxide powder, the potential of ferric oxide can be erased with a smaller amount of reduction than when reducing powdered silver oxide powder. 〇Figure 2 shows 10S oxidized second chain granules with an average particle size of 10Gpm.
1 g of silver a-chloride reduced to 1 g and 1 g of ferric oxide powder with an average particle size of 5 sst reduced to 10-ferrous oxide were each added to a 25'14 sodium hydroxide aqueous solution at 46°C.
This is a diagram showing the relationship between the storage time and the amount of oxygen gas generated when stored in K. As shown in Figure 2, granules generate less oxygen gas than powder. This shows that the decomposition of ferric oxide is less than that of powdered granules. The following Table 1 shows that the surface of oxidized second chain granules with an average particle size of 101+m was reduced to ferric oxide and used as a positive electrode active material. The electrical properties of the battery A of the present invention used as the material and of the conventional fiB using as the positive electrode active material the surface of ferric oxide powder with an average particle size of 6 μm reduced to silver oxide are often shown. 0 In battery A, 5'''q is applied to eliminate the potential of silver oxide.
btm, reduced to ferrous chloride, and in battery B, reduced to 8096 & ferric oxide. In addition, the reduction was carried out at 100% in a nitrogen atmosphere.
The 90 batteries were made by thermal decomposition at °C and had a diameter of 11.6 m, each having the configuration shown in Figure 8.
It is a button type battery with a thickness of 2.0 m, and the positive electrode (1) is made of 210'lF of silver oxide as described above at 5 t/a2 with a diameter of 11
Qu, pressure molded to a thickness of 0.4 mm, (2) is a positive electrode can, (3) is a separator, and this separator (3) has glass 7 on both sides of the cello no. It is a laminated film (a graft film in which methacrylic acid is graft-polymerized to a cross-linked low-density polyethylene film). (4) is an electrolyte absorber made of polypropylene nonwoven fabric, and (5) is a negative electrode using amalgamated zinc as an active material.Battery A uses 90q of amalgamated zinc, and battery B uses 7@at. 0 (6) is a negative 117A glass plate in which amalgamated lead is used, and (7) is an annular gasket. As the electrolyte, an aqueous solution of fC 26% sodium hydroxide IJ lime is used by dissolving zinc oxide. The open circuit voltage is set at 20°C, and the closed circuit voltage is set to 2Ω at 20°C.
Measured after discharging for 5 seconds, hυ, discharge, capacity is 20
Table 1 As shown in Table 1, the battery A of the present invention has a larger discharge capacity than the conventional battery B. This is considered to be because the amount of reduction required to eliminate the silver oxide potential was reduced by granulating the oxidized second chain.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the composition ratio of silver oxide and silver oxide and the closed circuit voltage, Figure 2 is a diagram showing the relationship between the storage time of silver oxide and the amount of oxygen gas generated; FIG. 8 is a cross-sectional view showing one embodiment of the silver oxide battery of the present invention. (1)...Cathode patent applicant Hitachi Maxell Ltd. Ag2O020
406080100 Ag100A 80 60 40 20 0 Fig. 2 100 200 Storage A Ginma (h) Fig. 3 α

Claims (1)

[Claims] Particle size 50 to 600 μm with l1 surface reduced to silver oxide
A silver oxide battery characterized by using oxidized second chain granules of as a positive electrode active material.