JPS6177260A - 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 indium, thallium, and tellurium to zinc used as a negative active material. CONSTITUTION:Zinc alloy containing 0.01-0.5wt% indium, 0.01-0.5wt% thallium, and 0.01-0.5wt% tellurium is used as a negative active material as it is or after amalgamation. When amalgamation is made, mercury content 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.

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 indium, thallium, and tellurium within 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, a strong alkaline electrolyte such as an aqueous potassium hydroxide solution is used, so the N pond must be sealed. This sealing of the battery is particularly important when trying to miniaturize the battery, but it also traps hydrogen gas that is generated due to corrosion of zinc during battery storage. Therefore, during long-term storage, the gas pressure inside the battery increases, and the more completely the battery is sealed, 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
They contain a large amount of mercury, which accounts for 50% of their total 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, in JP-A-58-218762, a zinc alloy powder in which two or more of gallium, indium, and thallium are added to zinc is proposed, and in particular zinc-indium-thallium. In the system, initial gas generation is greatly suppressed, but
There is a phenomenon in which the rate of gas generation gradually increases with the passage of time. This phenomenon has a serious effect on the battery characteristics after long-term storage.

As described above, a battery has not yet been obtained which reduces the hydrogen gas generation amount while reducing the flux of the zinc alloy powder as the negative electrode active material, and which also maintains a high level of discharge performance, which is the battery performance.

(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) In line with this purpose, the present inventors have conducted intensive research and have discovered that by adding indium, thallium, tellurium, etc. in specific ranges to negative electrode active materials 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 has a lower long-term hydrogen gas generation amount than a zinc alloy powder in which only indium and thallium are added to zinc, and has excellent discharge performance, and has arrived at the present invention.

(Structure of the Invention) Accordingly, the present invention contains 0.01 to 0.5% by weight of indium, 0.801 to 0.5% by weight of thallium, and 0.0801 to 0.5% by weight of tellurium.
．． The present invention provides a zinc alkaline battery characterized in that a zinc alloy containing 01 to 0.5% by weight is used as a negative electrode active material.

In the present invention, a zinc alloy to which indium, thallium, and tellurium are added in a specific order of magnitude 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 starch. The mercury content in the case of oxidation is lower than the mercury content of conventional negative electrode active materials, that is, less than 5.0% by weight. .0% by weight or less. 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, 1. Zinc alloys with a low or non-grading rate of 0 weight percent or less are preferably used as the negative electrode active material.

The content of indium, thallium, and tellurium in the zinc alloy used in this negative electrode active material is 0.01 to 0.5, respectively.
The effect of addition is exhibited in small amounts (weight%). If the content of indium, thallium, and tellurium 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 progresses like zinc containing impurities, resulting in gas generation. No good results are obtained for suppression and discharge performance. It is currently not clear why the tellurium used here is effective, but it is said that tellurium forms an intermetallic compound with zinc, and this property is thought to bring about good results. However, the effects of the present invention cannot be obtained with tellurium alone or with a combination of indium and tellurium, or thallium and tellurium, but in the present invention, a synergistic effect can be obtained by the combination of indium, thallium, or tellurium as described above.

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.

Examples 1 to 3 and Comparative Examples 1 to 4 A zinc ingot with a purity of 99,997% or more is melted at about 500°C, and as shown in Table 1, the contents of indium, thallium, and bismuth are each 0.0. 0.1% by weight to create a zinc alloy, which was pulverized using high-pressure argon gas (ejection pressure 5Kg/ci).Next, the above was added in an alkaline solution of 10% potassium hydroxide. Mercury was added to the powder to give a concentration of 1.0% by weight, and the powder was subjected to a hydration treatment to obtain a zinc alloy powder (Example 1).

In addition, as shown in Table 1, with the following composition, (1): indium (1.05% by weight, thallium 0.05% by weight,
Tellurium 0.05% by weight, (2): Indium 0.5% by weight, Thallium 0.5% by weight, (3): Indium\0.5% by weight, Thallium 0.5% by weight, (4): Indium 0.5% by weight, tellurium 0.5% by weight
, (5): 0.5% by weight of thallium, 0.5% by weight of tellurium, and (6): 0.5% by weight of tellurium. , the mercury content is reduced to 1 after the oxidation treatment.
．． 0% by weight of zinc alloy powder (Examples 2-3 and Comparative Examples 1-4) was prepared.

A hydrogen gas generation test was conducted using the zinc alloy powder thus obtained, and the results are shown in Table 1. In the gas generation test, 5 mQ of a 40% by weight potassium hydroxide aqueous solution saturated with zinc oxide was used as the electrolyte, and 10% of zinc alloy powder was used at 45°C for 50 days. The amount of gas generated (m/g) 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 composed 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. There is. Using this alkaline manganese battery, the discharge duration up to the final voltage of 0.9V was measured under the discharge conditions of 4Ω discharge load and 20°C, and the measured values were obtained in Comparative Example 5, which will be described later, using a conventional negative electrode active material. It is expressed as an index with 100. The results are shown in Table 1.

Comparative Example 5 A conventionally used zinc chloride powder in which 5.0% by weight of mercury was added to zinc using the same method as in Example 1 (Comparative Example 5)
I got it.

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, Examples 1 to 3 used a zinc hydride alloy powder as a negative electrode active material, which was made by adding specific amounts of indium, thallium, and tellurium to zinc to extremely reduce the mercury content and turn it into a vapor. 3 is Comparative Examples 1 to 4 in which indium and thallium, indium and tellurium, thallium and tellurium, or only tellurium was added as the negative electrode active material, and the conventional method in which only mercury was added to zinc. Compared to Comparative Example 5 in which the zinc chloride powder used was used as the negative electrode active material, not only was the initial hydrogen gas generation suppressed,
Hydrogen gas generation is suppressed over a long period of time. Moreover, it can be seen that Examples 1 to 3 are also superior in discharge performance compared to Comparative Examples 1 to 5.

(Effects of the Invention) As explained above, the zinc-alkaline battery of the present invention, in which a zinc alloy containing indium, thallium, and tellurium in a specific range is used as a negative electrode active material as it is or after being converted into a hydrogen atom, has a high hydrogen gas generation rate over a long period of time. It is possible to improve battery performance while suppressing mercury, and because it contains low or no mercury, it meets social needs. Therefore, the zinc-alkaline battery of the present invention can be used in a wide range of applications.

[Brief explanation of the drawing]

FIG. 1 shows a sectional view of an alkaline manganese battery according to the present invention. 1: positive electrode can, 2: positive electrode, 3: t? Palator 14: negative electrode, 5: negative electrode current collector, 6: rubber packing, 7: holding plate.

Claims (1)

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