JPS62176052A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To reduce the evolution of hydrogen gas and to improve discharge performance by using a zinc alloy containing a specified amount of Co and Ga, and a specified total amount of at least one selected from In, Pb, and Cd as a negative active material. CONSTITUTION:0.005-0.5wt% each of Co and Ga, and 0.005-0.5wt% at least one selected from In, Pb, and Cd are added to melted pure zinc to obtain a zinc alloy. The zinc alloy is powdered by using Ar gas. A specified amount of Hg is added to the Zinc alloy powder in a KOH solution to obtain amalgamated zinc alloy powder. This powder is used to form an alkaline manganese battery comprising a positive can 1, a positive electrode 2, a negative electrode 3, a separator 4, a sealing member 5, and a negative current collector 7 and others. The zinc alkaline battery having the negative active material whose discharge performance is high and hydrogen gas evolution is retarded is spit of reduced mercury content can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a zinc-alkaline battery, and more specifically, a zinc alloy containing cobalt, gallium, and one or more selected from indium, lead, and cadmium within a specific range. This invention relates to a zinc-alkaline battery that uses Zinc as a negative electrode active material either as it is or after it has been converted into a hydrogen acetate.

[Prior Art] In alkaline batteries using zinc as a negative electrode active material, a strong alkaline electrolyte such as an aqueous potassium hydroxide solution is used, so the battery must be closed. This sealing of the battery is particularly important when attempting to miniaturize the battery, but it also traps hydrogen gas generated due to corrosion of zinc during battery storage. Therefore, during long-term storage, the gas pressure inside the battery increases, and the more the battery is completely drained, the greater the risk of an 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 materials of alkaline batteries commercially available today are 3 to 10
They contain a large amount of mercury, on the order of % by weight, and as a social need, there have been 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 are zinc alloy powders in which lead is added to zinc, or zinc alloy powders in which lead and indium are added to zinc (Japanese Unexamined Patent Publication No. 181266/1983).

[Problems to be solved by the invention] However, although the zinc alloy powder proposed above has a certain degree of gas generation suppressing effect, it has not yet reached a satisfactory level in reducing the mercury content to less than 3%. do not have.

As described above, a battery that reduces hydrogen gas generation while maintaining a high level of discharge performance, which is battery performance, while using a zinc alloy powder as a negative electrode active material, has not yet been developed.

In view of the current situation, an object of the present invention is to provide a zinc-alkaline battery using a negative electrode active material that significantly reduces the content of mercury, suppresses hydrogen gas generation, and maintains discharge performance at a high level. do.

[Means for Solving the Problem] As a result of intensive research in line with this purpose, the present inventors have found that a negative electrode active material whose main component is zinc, selected from cobalt and gallium, as well as indium, lead, and cadmium. be able to
By adding one or more elements in a specific range, the synergistic effect of these additive elements reduces the amount of water-based gas generated even more than the conventional low-strength zinc alloy powder, and further improves the discharge performance. The inventors have discovered that a zinc-alkaline battery can be obtained and have arrived at the present invention.

That is, in the present invention, the total amount of cobalt is o, oos ~ 0.5% by weight, gallium is o, oos ~ 0.5% by weight, and the total amount of one or more selected from indium, lead, and cadmium is 0.5% by weight.
The present invention provides a zinc alkaline battery characterized in that a zinc alloy containing 0.005 to 0.5% by weight is used as a negative electrode active material.

The cobalt content of the zinc alloy used in this negative electrode active material is 0.005 to 0.5% by weight, and the gallium content is 0.
．． The content of one or more selected from indium, lead, and cadmium is as low as o, oos to 0.5% by weight, and the effect of addition is exhibited. If the content of each added element is less than the lower limit, the effect of the present invention cannot be obtained, and if it exceeds the upper limit, self-discharge progresses due to the opposite effect of element addition, and good results are obtained for suppressing gas generation and discharge performance. do not have.

The above zinc alloy can be used as a negative electrode active material, or
Zinc alloy is used as a negative electrode active material after being converted into a metal. Even if the mercury content in the case of corrosion is lower than the mercury content of conventional negative active materials, that is, less than 3.0% by weight, the corrosion resistance is high. Further, by lowering the mercury content by lowering the mercury content, sufficient corrosion resistance can be ensured even if the mercury content is 1.5% or less, taking into consideration low pollution. Furthermore, it is possible to suppress gas generation even if the content is 1.0% by weight or less. In particular, in air batteries equipped with an exhaust mechanism or zinc-alkaline batteries equipped with a hydrogen absorption structure, the permissible amount of hydrogen gas generated is relatively large, so when applying the present invention to such batteries, 1. It is also possible to use a zinc alloy with a low hydration rate of .0% by weight or less or no hydration as the negative electrode active material.

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.

[Function] Although the effects of each of these elements are not fully elucidated,
It is presumed that cobalt contained in zinc alloys is known to be a corrosion-resistant metal in itself, but it is also thought to help suppress local corrosion reactions when it is solutionized with zinc. .

Further, gallium, indium, lead, and cadmium are thought to have the effect of increasing hydrogen overvoltage or suppressing corrosion of zinc in an alkaline electrolyte.

In the present invention, a zinc alloy layer with corrosion resistance and discharge performance is improved due to the synergistic effect of each of these functions.

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

Fruit 711 i rows 1 to 18 and comparative examples 1 to 9 purity 99.
A zinc alloy containing 97% or more of zinc is melted at approximately 500°C, and cobalt, gallium, and indium are added to the melt at a content of 0.05% by weight each as shown in Table 1 to form a zinc alloy. This was then pulverized using high-pressure argon gas (ejection pressure 5 kg/cti). Next, add the above powder to an alkaline solution of 10% potassium hydroxide.
Adding mercury to a concentration of 1.0% by weight, and carrying out a hydration treatment, the oxidation zinc alloy powder (Example 1) was reduced to 1.0% by weight. ? Ta.

In addition, zinc alloys were prepared with the compositions shown in Table 1, which were pulverized in the same manner as described above, and subjected to a filtration treatment to produce zinc alloys with a mercury content of 1.0w%. Powder (
Eggplant examples 2 to 18J and comparative examples 1 to 9) were obtained.

A hydrogen gas generation test was conducted using the zinc chloride alloy powder thus prepared, and the results are shown in Table 1.

In addition, in the gas generation test, an aqueous solution of potassium hydroxide with a concentration of 40% by weight and a saturated solution of zinc oxide were used as the electrolyte.
Using 10 ml of zinc alloy powder (using 5 ml at 45°C)
Gas generation FA <i/'(]) for 0 days was measured.

In addition, heavy oil performance was planned using the alkaline manganese battery shown in FIG. 1 using these subfi1 alloy powders as a negative electrode active material. The alkaline manganese battery shown in Figure 1 consists of a positive electrode can 1,
It is composed of a positive electrode 2, a negative electrode 3, a separator 4, a sealing body 5, a negative electrode bottom plate 6, a negative electrode current collector 7, a cap 8, a heat-shrinkable resin tube 9, an insulating ring 10° 11, and an outer can 12. Using this alkaline manganese battery, the discharge load is 4Ω,
The discharge duration up to the final voltage of 0.9 V was measured under the discharge condition of 20° C., and expressed as an index with the measured value of Comparative Example 10 (after using a conventional negative electrode active material) as 100. The results are shown in Table 1.

Comparative Example 10 A conventionally used zinc chloride alloy powder (Comparative Example 10) in which 5.014% of mercury was added to zinc was prepared in the same manner as in Example 1. A hydrogen gas generation test and a battery performance test were conducted using the method described above, and the results are shown in Table 1.

As shown in Table 1, zinc oxide alloy powder, which is made by adding cobalt, gallium, and one or more selected from indium, lead, and cadmium to zinc and turning it into oxide, was used as the negative electrode active material. Examples 1 to 18 show that hydrogen gas generation is higher than Comparative Example 1 to Comparative Example 10, in which a conventionally used zinc chloride alloy powder in which only mercury is added to zinc is used as the zero electrode active material. It can be seen that the suppression effect is large and the discharge performance is also excellent.

[Effects of the Invention] As explained above, the present invention uses a zinc alloy containing cobalt, gallium, and one or more selected from indium, lead, and cadmium in a specific range as a negative electrode active material, either as it is or after being made into a liquid. Zinc-alkaline batteries can improve battery performance while suppressing the hydrogen gas generation rate, and also meet social needs because they contain 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 side sectional view of an alkaline manganese battery according to the present invention. 1: positive electrode can, 2: positive (lagoon), 3: negative (i14: separator, 5: sealing body, 6: negative electrode bottom plate, 7: negative electrode current collector, 8: cap, 9: heat-shrinkable resin tube, 10. 11: Insulation ring, 12: Exterior can.

Claims (1)

[Claims] 1. 0.005 to 0.5% by weight of cobalt, 0.005 to 0.5% by weight of gallium, and a total amount of one or more selected from indium, lead, and cadmium of 0.005% by weight. ~0.5
A zinc-alkaline battery characterized by using a zinc alloy containing % by weight as a negative electrode active material. 2. The zinc-alkaline battery according to claim 1, wherein the zinc alloy is made of aluminum.