JPS6177256A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To decrease mercury content, retard hydrogen gas evolution, but still keep high discharge performance by adding a specified amount of lead, indium, and silver to zinc used as a negative active material. CONSTITUTION:Zinc alloy containing 0.01-0.5wt% lead, 0.01-0.5wt% indium, and 0.01-0.5wt% silver is used as a negative active material as it is or after amalgamation. When amalgamation is made, mercury content after amalgamation is decreased to less than 5wt% which is lower than that of usual negative active material. In an air cell having a gas vent or a zinc alkaline battery having a hydrogen absorption means, zinc alloy having 1.0wt% or less mercury or no mercury can be used preferably as a negative active material, because allowable hydrogen gas evolution volume is relatively large.

Description

[Detailed Description of the Invention] (Field of the Invention) The present invention relates to a zinc-alkaline battery, and more specifically, a zinc alloy containing lead, indium, and silver in a specific range is used as a negative electrode active material for a battery, either as it is or after being made into a liquid. Regarding zinc alkaline batteries.

(Background of the Invention) In alkaline batteries and the like that use zinc as a negative electrode active material, the batteries must be sealed tightly because a strong alkaline electrolyte such as an aqueous potassium hydroxide solution is used. This sealing of the battery is particularly important when attempting to miniaturize the battery, but it also traps hydrogen gas generated by corrosion of zinc during battery storage. Therefore, during long-term storage, the gas pressure inside the battery increases, and the more completely sealed the battery is, the greater the risk of explosion.

As a countermeasure, research has been conducted to prevent corrosion of zinc, which is an active material for the negative electrode, and to reduce the generation of hydrogen gas inside the battery. It is being done. For this reason, the negative electrode active material of alkaline batteries commercially available today is 5 to 10
It contains a large amount of mercury, on the order of % by weight, and as a social need, there are strong expectations for the development of lower mercury or mercury-free batteries.

Therefore, various proposals have been made regarding zinc alloy powders in which various metals are added to zinc in order to reduce the mercury content in batteries. For example, there is a zinc alloy powder made by adding lead to zinc, or a zinc alloy powder made by the present inventors by adding lead and indium to zinc (Japanese Unexamined Patent Publication No. 181266/1983). However, although these zinc alloy powders have a certain degree of gas generation suppressing effect, it is still not sufficient. For example, when zinc alloy powder is made by adding lead and indium to zinc and the mercury content is reduced to about 1% by weight, gas generation is extremely suppressed in the early stage of the gas generation test, but over a long period of time. There was a tendency for the gas generation rate (me/(1·day)) to gradually increase over time.

As described above, a battery has not yet been obtained in which the zinc alloy powder, which is the negative electrode active material, has a low resistance, reduces the amount of hydrogen gas generated, and maintains the discharge performance, which is the battery performance, at a high level.

(Object of the Invention) In view of the current situation, the present invention provides a zinc-alkaline battery using a negative electrode active material that significantly reduces mercury content, suppresses hydrogen gas generation, and maintains discharge performance at a high level. The purpose is to

(Background of the invention) As a result of intensive research in line with this purpose, the present inventors found that by adding lead, indium, and silver in specific range amounts to a negative electrode active material made of zinc, the synergistic effects of these additive elements The present inventors have discovered that, due to these effects, it is possible to obtain a zinc-alkaline battery that further reduces the amount of hydrogen gas generated than conventional zinc alloy powders with reduced flux and has excellent discharge performance, and has arrived at the present invention.

(Structure of the Invention) That is, the present invention contains 0.01 to 0.5% by weight of lead, 0.01 to 0.5% by weight of indium, and 0.01 to 0.0% of silver.
A zinc-alkaline battery is characterized in that a zinc alloy containing 5% by weight is used as a negative electrode active material.

In the present invention, a zinc alloy to which specific amounts of lead, indium, and silver are added is used as a negative electrode active material as it is, or is used as a negative electrode active material after the zinc alloy is converted into a liquid. The mercury content in the case of oxidation is lower than that of conventional negative electrode active materials, that is, less than 5.0% by weight, but if the mercury content is lower than that of conventional negative electrode active materials, and considering low pollution properties, .0% by weight
It is as follows.

Further, even if the content is as small as around 1.0% by weight or less, it is possible to suppress gas generation. In particular, in air batteries equipped with an exhaust mechanism, zinc-alkaline batteries equipped with a hydrogen absorption mechanism, etc., the permissible amount of hydrogen gas generated is relatively large, so when applying the present invention to such batteries,
A zinc alloy with a low or non-grading rate of 1.0% by weight or less is preferably used as the negative electrode active material.

The content of lead, indium, and silver in the zinc alloy used in this negative electrode active material is as small as 0.01 to 0.5% by weight, respectively, and the effect of addition is exhibited. If the content of lead, indium, and silver is less than 0.01% by weight, the effect of the present invention cannot be obtained, and if it exceeds 0.5% by weight, self-discharge will progress like zinc containing impurities and gas generation will be suppressed. and good results for discharge performance cannot be obtained. Although the effects of silver used here are not clear, the amount of gas generated is less than half that of the conventionally proposed zinc alloy in which lead and indium are added to zinc as the negative electrode active material. was found to be suppressed.

As described above, the zinc-alkaline battery of the present invention uses an alkaline aqueous solution containing caustic potash, caustic soda, etc. as the main component as an electrolyte, the above-mentioned zinc alloy or aqueous zinc alloy as a negative electrode active material, and manganese dioxide, as a positive electrode active material, Obtained by using silver oxide, oxygen, etc.

(Description of Examples) The present invention will be specifically described below based on Examples and Comparative Examples.

119, 21 Zinc ingot with a purity of 99,997% or more is melted at about 500'C, and the contents of lead, indium, and silver are each 0.05% by weight as shown in Table 1. to create a zinc alloy, which is then heated with high-pressure argon gas (ejection pressure 5
tC'j/c! ＞ was used to make powder. Next, 1.0% by weight of J: mercury was added to the powder in an alkaline solution containing 10% potassium hydroxide, and the powder was subjected to a hydrochloric treatment to obtain a zinc alloy powder (Example 1).

In addition, the ratios of lead, indium, and silver are shown in Table 1, respectively.
A zinc alloy of 5% by weight, ■: 0.01% by weight of lead, 0.01% by weight of indium, and 0.01% by weight of silver was prepared, and this was pulverized in the same manner as described above. The treatment yielded zinc alloy powders (Examples 2-3) with a mercury content of 1.0% by weight.

A hydrogen gas generation test was conducted using the zinc alloy powder thus obtained, and the results are shown in Table 1. In addition, the gas generation test was performed using 5ME, an electrolyte prepared by saturated zinc oxide in a potassium hydroxide aqueous solution with a concentration of 40% by weight, and 10% zinc alloy powder (1) for 50 days at 45°C. The generation M (mff/(]') was measured.

Further, battery performance was evaluated using an alkaline manganese battery shown in FIG. 1 using these zinc alloy powders as a negative electrode active material. The alkaline manganese battery shown in FIG. 1 is made up of a positive electrode can 1, a positive electrode 2, a separator 3, a negative electrode 4 made of zinc alloy powder gelled with carboxymethyl cellulose, a negative electrode current collector 5, a rubber packing 6, and a holding plate 7. ing. Using this alkaline manganese battery, we measured the discharge duration to a final voltage of 0.9V under discharge conditions of 4Ω discharge load and 20°C.
The measured values of Comparative Example 2, which will be described later, using a conventional negative electrode active material are expressed as an index multiplied by 100. The results are shown in Table 1.

Comparative Examples 1-2 0.05 weight h1 of 141 was added to zinc in the same manner as in Example 1.
% of lead and indium (Comparative Example 2) were obtained.

This was subjected to a hydrogen gas generation test and a battery performance test in the same manner as in Example 1, and the results are shown in Table 1.

As shown in Table 1, in Examples 1 to 3, the negative electrode active material was a zinc chloride alloy powder obtained by adding specific amounts of lead, indium, and silver to zinc. Compared to Comparative Example 1 in which a zinc chloride alloy powder was used as the negative electrode active material and Comparative Example 2 in which a zinc chloride alloy powder in which lead and indium were added to zinc was used as the negative electrode active material, the effect of suppressing hydrogen gas generation was greater. It can be seen that the discharge performance is also excellent.

(Effects of the invention) As explained above, the zinc-alkaline battery of the present invention, which uses a zinc alloy containing lead, indium, and silver in a specific range as a negative electrode active material either as it is or after it has been converted into a liquid, suppresses the hydrogen gas generation rate. However, it is possible to improve battery performance, and it also meets social needs because it contains low or no mercury. Therefore, the zinc-alkaline battery of the present invention can be used in a wide range of applications.

[Brief explanation of drawings]

FIG. 1 shows a sectional view of an alkaline manganese battery according to the present invention. -1n - 1: positive electrode can, 2: positive electrode, 3: separator, 4: negative electrode,
5: Negative electrode current collector, 6: Rubber packing, 7: Pressing plate. Patent applicant Mitsui Kinzoku Mining Co., Ltd. Patent applicant Matsushita Electric Industrial Co., Ltd. Agent Patent attorney Tatsuo Ito Agent Patent attorney Tetsuya Ito Figure 1

Claims (1)

[Claims] 1. 0.01 to 0.5% by weight of lead, 0.0% of indium
A zinc-alkaline battery characterized in that a zinc alloy containing 1 to 0.5% by weight and 0.01 to 0.5% by weight of silver is used as a negative electrode active material. 2. The zinc-alkaline battery according to claim 1, wherein the zinc alloy is made of aluminum.