JPS5851477A - Silver-oxide battery - Google Patents

Abstract

PURPOSE:To enable a silver-oxide battery to be made thin by improving the weighing accuracy and the moldability of a positive active material by using as the positive active material, silver-oxide granules having specified grain diameters and a specified bulk density. CONSTITUTION:Silver-oxide powder is made into granules with diameters of 50-500mu and a bulk density of 1.5-3.5g/cm2, and the granules are used as a positive active material. By the means mentioned above, since the fluidity of the positive active material can be widely improved compared to a powdery active material, the weighing accuracy and the moldability are increased. As a result, the variation in the packed amount of the positive active material is reduced even in manufacturing a thin battery. In addition, the moldability during the press molding of the positive mixture is increased. Consequently, a silver-oxide battery with a reduced generation of formation deficiency can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvement of silver oxide batteries, by granulating silver oxide,
The purpose is to improve weighability and moldability, and to make it possible to provide thin batteries. Conventionally, silver oxide (with a particle size of 0.1 to 10 usw) is used as a positive electrode active material in an oxidation pond. Ag20 or Age) powder was used, but the fluidity is fast,
Therefore, weighability and moldability are poor, and in particular, in thin batteries with a small amount of positive electrode active material filled, there are problems in that the filling amount varies widely and the failure rate during pressure molding increases.

Therefore, phosphorous graphite is added to the positive electrode active material to provide electron conductivity, but in order to provide sufficient activity, a considerable amount of phosphorous graphite must be added in terms of volume. However, this has the disadvantage that the discharge capacity decreases and it is not possible to increase the capacity.

The inventors of the present invention have repeatedly studied this situation and found that silver oxide powder has a particle size of 50 to 500 μm, a force density of 1.
5~! i, When granulated to 5 f/cm2 and used as a positive electrode active material, silver oxide granules have significantly improved fluidity and improved vibration suppression and moldability compared to when using powdered silver oxide granules. By doing so, it is possible to obtain a silver oxide battery with less variation in the optical side cover even in the case of a thin battery with a small filling amount of positive electrode active material, and with improved moldability during pressure molding and with less occurrence of molding defects. They discovered this and completed the present invention.

In order to obtain the above-mentioned silver oxide granules used in the present invention, for example, silver oxide powder having a normal particle size of 0.1 to 10 μs go # is made into a slurry with water and granulated with a granulator, preferably into spherical particles. It can be sized into spheres using a machine and then dried.

In the present invention, the particle size of silver oxide granules is 50 to 500μ.
m is chosen because if the particle size is smaller than this, the fluidity will decrease, and weighability and moldability will decrease accordingly, and conversely, if the particle size is larger than the above range, it will be thin with less light *-. This is because, in a battery, the influence of the filling tK of one granule becomes large, and variations in light charging tend to occur.

Bulk density affects moldability, and the higher the bulk density to some extent, the stronger the bond between particles during pressure molding and the better the moldability, but if the gap is high, it becomes difficult for individual particles to be compressed. On the contrary, the moldability deteriorates. The bulk density has a relationship with the particle size, and within the above range, the larger the particle size, the better the bulk density.

In the present invention, by granulating silver oxide,
Since the t&dynamics can be greatly improved, the addition sensitivity of phosphorous graphite can be reduced, and the cost of mass cutting can be reduced without using a large amount of phosphorous graphite. Although the amount of phosphoric graphite can be reduced to 0.05 to 2
% (lHiL%, hereinafter the same) may be added.

The following Table 1 shows the relationship between the particle size of silver oxide (*g2o, hereinafter referred to as the same) and weighability.We investigated the variation when weighing silver oxide of various particle sizes using the mass cutting method in 2004. The results are shown below.

Table 1 Figure 1 shows the relationship between silver oxide particle size and bulk density. Figure 2 shows the relationship between silver oxide particle size and bulk density.
This shows the results of investigating the incidence of defects due to cracking and chipping K when pressure-forming to a thickness of 0.5 m.0 As is clear from the results shown in Table 1 and Figures 1 and 2. 1 particle size range from 50 to 500 μm, bulk density, 5 to g, 5jl
Within the range of /2-, there is little variation in the weighing value, and there is little occurrence of molding defects.

Table 2 shows the discharge capacity t of the battery @A of the present invention using silver oxide granules with an average particle size of 100 μm as the positive electrode active material and the conventional battery B using silver oxide powder with an average particle size of 5 μm as the positive electrode active material.
This shows that.

For battery A, 100 parts of the silver oxide granules (3 lid parts, the same shall apply hereinafter) were cut into 200 jlFff using a mass cutting method, and the amount was 5 L/c.
x2 was pressure-molded to a diameter of 9 sm and a thickness of 0.5 M, and this was assembled into a 1 ta as a positive electrode. On the other hand, for battery B, 95 parts of the silver oxide powder and 5 parts of cylindrical graphite were mixed, weighed to 1,701 mm using a mass cutting method, and pressed to a diameter of 9 aI and a thickness of 0.5 m using 61/32. , which was incorporated into a battery as a positive electrode.

Each battery has a diameter of 9 and has the configuration shown in Figure 3.
．． It is a button type battery with a length of 5 m and a thickness of 2 M, and in Fig. 8, (1) is the positive electrode as described above, (2) is the positive electrode can, (
3) is a separator, (4) is an electrolytic f & absorber, (5)
is a negative electrode with amalgamated zinc as the active material, battery A
55 Cape amalgamated zinc is used, and DenfiB uses 444 amalgamated zinc (6)
is the negative electrode terminal plate, (7) is the annular gasket, and as the electrolyte, S5 potassium hydroxide aqueous solution in which zinc oxide is dissolved is used, and the discharge capacity of both batteries is 100
Measurements were made by continuously discharging each battery at 20°C, 22 ohms, and a final voltage of 1.2 volts. As a result, as shown in Table 2, the discharge capacity is improved by approximately 26 seconds compared to conventional batteries, resulting in a battery life of 90 seconds.

[Brief explanation of drawings]

Figure 1111 is a diagram showing the relationship between the grain size of silver oxide and bulk density, Figure 2 is a diagram showing the relationship between the grain size of silver oxide and the failure rate during pressure molding, and Figure @8 is a diagram showing the relationship between the grain size of silver oxide and the bulk density. 0(1)-1, which is a cross-sectional tooth showing an example of a silver oxide battery, positive electrode patent applicant Hitachi Maxell Co., Ltd. L%-

Claims (1)

[Claims] 1. Particle size 5G~50 (9m, bulk density 1.5~8.51
Silver oxide battery 0 characterized by using silver oxide granules of /lx2 as a positive electrode active material