JPS6056366A - Alkaline battery - Google Patents

Abstract

PURPOSE:To improve weighing accuracy and stabilize the performance of an alkaline battery by preparing a negative agent from zinc powder containing at least 90wt% of spherical zinc particles having a mesh of 100-200 and a longer axis diameter/shorter axis diameter ratio of 1.1 or below. CONSTITUTION:Zinc powder containing at least 90wt% of zinc particles of 100- 200 mesh manufactured by a rotary drum method and having a longer axis diameter/shorter axis diameter ratio of 1.1 or below, is amalgamated with 10pts. wt. (to 100pts.wt. of the above zinc powder) of mercury to prepare a negative agent. Next, after a negative electrode 7 is formed by the negative agent, the negative electrode 7 is combined with a positive electrode 1, a separator 3, an electrolyte-absorbing body 4 and the like, thereby constituting a button-type silver oxide battery. As a result, weighing accuracy can be widely improved due to an improved fluidity of the negative agent achieved by restricting the form of the zinc particles. Consequently, it is possible to sufficiently cope with a decreased size of the battery and to stabilize the discharge performance of the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alkaline electrolyte using zinc powder as a negative electrode active material.

In conventional batteries of this type, the lead powder used as the negative electrode active material is generally 32 mm in order to increase the discharge reaction area per weight.
Irregular, elongated shaped particles with particle sizes of ~200 mesh have been used. However, such particles have poor fluidity, and when weighing by volume scraping such as mass weighing using a popper, the weight of the weighed zinc powder tends to vary, which makes it difficult to maintain stable battery characteristics. The problem was that it was difficult to obtain. In recent years, however, as batteries have become smaller and fewer active materials have been used, one stone between the balance W and accuracy has become a major cause of inhibiting the stabilization of battery characteristics. ing.

On the other hand 1. In order to overcome the above problems, we have developed an approximately spherical particle with a particle size in a certain range of 48 to 80 mesh as the total active material, and a ratio of major axis diameter / minor axis diameter of 15 or less. An alkaline battery using zinc particles has been proposed (Japanese Unexamined Patent Application Publication No. 117869/1983), and this battery certainly improves the stability of the battery characteristics due to the improvement in the accuracy of the scale ijV. can.

The inventors have found that by adding ia □ to the zinc particles proposed above, it is possible to further improve the accuracy of the scale Jij, thereby further contributing to the stabilization of battery characteristics, and to improve the closed-circuit voltage at the end of the load period for closed-circuit voltage ships. As a result of extensive research aimed at finding qlU lead powder, we learned that zinc powder with a specific particle shape and particle size is extremely suitable for the above purpose. This invention has been made.

That is, the present invention provides an alkaline battery using zinc powder as a negative electrode active material, in which 90% by weight or more of the zinc powder is 10% by weight or more.
The present invention relates to an alkaline battery characterized by comprising spherical zinc particles having a particle size of 0 to 200 mesh and a ratio of major axis diameter/minor axis diameter of 11 or less.

At least 90% by weight of the zinc powder used in this invention is
The ratio of major axis diameter/minor axis diameter is 11 or less, that is, 10 to 1
It has a spherical particle shape within the range of 1. i! Based on the direction t of 4E dynamics (improvement in weighing accuracy can be expected to some extent. However, according to the inventor's experimental test d), the above improvement effect is achieved when the axial ratio becomes 1j or less. This has become extremely noticeable, and with the miniaturization of batteries -
Therefore, it has been found that even when the amount of active material is as small as about 10 yn7, a very high accuracy of the scale 1-11 can be obtained, and the scale can sufficiently cope with the above-mentioned miniaturization.

In addition, in this specification, the long axis diameter and short axis diameter of zinc powder are based on the general concept of powder, and are the distance between two parallel lines when a zinc particle is sandwiched between the lines. The width of the particle where the distance is the minimum is the short axis diameter, and the width of the particle where the above distance is the maximum is the long axis i.

A major feature of this invention is that the particle size of the zinc powder having the above-mentioned specific axial ratio is in the range of 100 to 200 mesh. In other words, this zinc powder is characterized by having a smaller particle size than the zinc powder proposed above, which increases the closed-circuit voltage, especially the closed-circuit voltage at the end of discharge. It was found that this method was effective. The reason for this is not necessarily clear, but it is thought that the smaller the diameter, the larger the discharge reaction area (approximately three times), and this is what gave the closed circuit voltage a favorable result.

However, if the particle size of the zinc powder becomes small enough to exceed 200 meshes, a problem will arise in the accuracy of the scale 11i, which is inappropriate. The zinc powder is amalgamated before use, i.e., during weighing. At this time, the above particle size is 200
This is because if the particle size exceeds the average particle size, agglomeration of particles will occur after amalgamation, resulting in poor fluidity and loss of weighing accuracy.

In order to produce the above-described specific zinc powder of the present invention, for example, molten zinc is forcibly sprayed together with air into a rotating drum filled with alkaline water, and cooled and granulated while being applied to the drum wall. It is good to adopt. In order to adjust the particle size, the control of the spray nozzle and the spray speed are related.
Adjusting the sphericity involves various conditions such as the drum rotation speed, the amount of spray, and the amount of alkaline water, so by appropriately setting these conditions, the zinc powder of the present invention having an axial ratio of +iiJ and a particle size can be obtained. can be easily obtained.

At the same time, in order to clarify the effects of using the above-mentioned zinc powder of the present invention, a more specific explanation will be given with reference to Examples and Comparative Examples.

Example 1) Zinc particles produced by the rotating drum method described above and having a ratio of major axis diameter/minor axis diameter of 11 or less and a particle size of 100 to 200 mesh account for 90 meshes or more of the total zinc powder, 1.00 parts by weight of this zinc powder was amalgamated using 10 parts by weight of mercury. Using this amalgamated zinc powder as a negative electrode material, a button-shaped silver oxide battery as shown in the drawing was produced.

In other words, first, silver oxide 185 n4 and graphite 15++
++';' was directly press-molded at a pressure of 5 tons/c17 (V 7 mn.

Thickness 1. A cathode material 1 of O, rtm was prepared, and this cathode material I was injected into iE-i'fi in which a part of the alkaline electrolyte was injected.
A separator 3 and an electrolyte absorber 4 were placed on the positive electrode material 1 in this order. - 10,000, periphery) 11S to the negative electrode can 0 formed by attaching the Ii; lj-shaped gasket 5 [) IJ written negative electrode agent 7 by mass scale 4 amount 54 m7 weigh 1
Fill it with 1 ru, and then add 1 of the remaining alkaline electricity! l
'l'7<&; J si 1 increased. This negative electrode can 6 and the positive electrode can in the above state? 11χa, the opening of the positive electrode can 2 is tightened and bent inward, and the inner peripheral surface is covered with an annular gasket 5.
By press-fitting and sealing 11, the button-shaped oxidation 4
A 14' pond was constructed.

In addition, the positive electrode can 2 used in the test was made of iron and plated with nickel according to Table 1iii, and the negative electrode can 6 was made of a copper-stainless steel-nickel clad plate. As the separator 3, a composite membrane laminated with kraft film (a kraft film made by polymerizing methacrylic acid with cross-linked low-density polyethylene filtration) on both sides of cellophane was used, and as the electrolyte absorber 4, a composite membrane of vinylon and rayon was used. Use mixed paper (-da.

Further, as an alkaline electrolyte, an aqueous solution of 35% by weight potassium hydroxide in which zinc oxide was dissolved was used. The diameter (outer diameter) of this battery is 7.9-771 il, and the sterility is 3.6 mrh.

Comparative Example 1 A conventional zinc powder having a particle size of 32 to 200 mesh and a ratio of major axis diameter/minor axis diameter in the range of 18 to 28 and having an elongated shape according to this rule was used as the negative electrode active material, and this was used as the negative electrode active material. The mixture was amalgamated into a negative electrode material in the same manner as described above, and a hotane type silver oxide battery was produced in exactly the same manner as in the examples.

Comparative Example 2 Zinc powder having a particle size of 48 to 80 mesh and having a ratio of major axis diameter/minor axis diameter in the range of 12 to 15 and accounting for 90% or more of the total zinc powder was used as a negative electrode active material. This was amalgamated into a negative electrode material in the same manner as in the example, and a silver oxide battery of the silver oxide type was produced using exactly the same instructions as in the example.

” 1. For each battery of Examples and Comparative Examples, -10°C at the beginning of discharge and at the end of discharge (depth of discharge 80%),
l 00Ω, closed circuit 7LLl after 5 seconds: The results were as shown in the table below. In addition, the mass scale of the negative electrode material used in the production of each battery was determined as shown in 1) in the table below.

In addition, the weighing accuracy described in "1" is the standard deviation (S) - 1Σ when weighing n times iI:] [X is the weighing p of each time,
value, or the average ht value of n times of weighing], and calculate this standard deviation (S) as the average amount l' ([Baka de i;+i'l
The coefficient of variation (S/also) was calculated to determine the low level of accuracy. In other words, a small coefficient of variation (1) means that the weighing accuracy is poor.63 As is clear from the table above, the alkaline battery of the present invention has a negative electrode material weighing precision that is lower than that of the conventional alkaline battery (Comparative Example 1). ) as well as the previously proposed alkaline battery (Comparative Example 2), the discharge characteristics are highly stabilized, and the durability is comparable to that of the conventional battery (Comparative Example 1). It can be seen that a high closed circuit voltage can be obtained at the beginning and end of discharge.

In addition, in the above example, when the ratio of the major axis diameter/minor axis diameter of the zinc powder was changed to 12 or less and 13 or less (particle size was 100 to 200 m2), the weighing accuracy of the anode material was 1" [
J coefficient of variation is 0.01.25 and 0.03, respectively.
80 and 1j. Based on this result, it is concluded that in order to obtain a high degree of weighing accuracy, the above-mentioned axial ratio must be set to 11 or less.

[Brief explanation of the drawing]

The drawing is a sectional view showing an example of an alkaline battery using the specific zinc powder of the present invention. DESCRIPTION OF SYMBOLS 1...Positive electrode material, 2. Positive electrode can, 3. Separator, 4. Electrolyte absorber, 6. Negative electrode housing, t... Negative electrode material. Patent applicant Hitachi Maxell, Ltd.

Claims (1)

[Claims] (1) In an alkaline battery using zinc powder as a negative electrode active material, 90% by weight or more of the drawn lead powder has a particle size of 100 to 200 mesh, the ratio of major axis diameter / minor axis diameter is 11 or less, and the following: 4. An alkaline battery characterized by being composed of spherical zinc particles.