JPH0822822A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To provide a low-environmental-pollution, safe, and high-performance zinc alkaline battery using unhardening and lead-unadded zinc alloy powder. CONSTITUTION:Unhardening and lead-unadded zinc alloy powder, which contains indium by 0.01-0.1wt.%, bismuth by 0.001-0.01wt.%, gallium by 0.001-0.05wt.%, and at least one kind or more being selected from among the group consisting of magnesium, calcium, barium, and beryllium by 0.001-0.05wt.% in total, is used for negative pole active matter 5. Furthermore, as an anticorrosive for the zinc alloy powder, this has a gel-shaped negative electrode 4 where indium compound is added by 0.005-0.5wt.% in terms of indium to the zinc alloy powder. This accomplishes the lower environmental pollution of the unhardening and lead-unadded battery, and besides gas occurs less than the case where unhardening and zinc alloy powder with lead added is used, so this is safe and high-performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-alkaline battery, and more particularly to a low-pollution, safe and high-performance zinc-alkaline battery using a lead-free zinc alloy powder.

[0002]

2. Description of the Related Art Conventionally, zinc negative alloy powder has been used as a negative electrode active material for zinc alkaline batteries for the purpose of suppressing gas generation due to corrosion of zinc and improving electrical characteristics. Since environmental pollution due to batteries has come to be regarded as a problem, there is a social demand for low pollution, and a zinc alloy composition and an anticorrosive agent (inhibitor) for making the zinc alloy powder non-silver (anhydrous). As a result, the gelled negative electrode for a mercury-free alkaline battery, which has no practical problems, was finally developed.

[0003]

However, in the unalloyed zinc alloy powder which has been put to practical use in a mercury-free alkaline battery, lead, which is a harmful substance like mercury, is contained in order to suppress generation of hydrogen gas. Since 100 ppm is added, the demand for a mercury-free alkaline battery using lead-free zinc alloy powder is increasing.

By the way, there are many patent publications of zinc alloys for zinc-alkali batteries to which lead has not been added up to now, such as JP-A-63-133450 and JP-A-2-194103. Some of them can be expected to have some degree of corrosion resistance, but they are not sufficient. Further, although it may be possible to use it for a battery having a structure for releasing generated gas, it is possible to improve the zinc alloy composition for a battery having a sealed structure such as a cylindrical alkaline manganese dry battery by simply improving the zinc alloy composition. Even if the generation of gas can be suppressed, the generation of gas after partial discharge cannot be suppressed and the gelled negative electrode cannot be practically used. Under such circumstances, there has been an urgent need to develop a zinc alloy composition with less gas generation and a gelled negative electrode applicable to an alkaline battery having a sealed structure.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a low-pollution, safe, and high-performance zinc-alkaline battery using a zinc alloy powder free of lead and containing no lead. is there.

[0006]

In order to solve the above-mentioned problems, a zinc alkaline battery according to claim 1 of the present invention comprises 0.01 to 0.1% by weight of indium and 0.001 to 0.
0.01% by weight, 0.001 to 0.05% by weight of gallium, and at least one selected from the group consisting of magnesium, calcium, barium, and beryllium in total of 0.0
A zinc alloy powder containing 0.01 to 0.05% by weight and containing no lead and no lead is used as a negative electrode active material, and an indium compound is used as a corrosion inhibitor for the zinc alloy powder in an amount of 0.005 in terms of indium with respect to the zinc alloy powder. It is characterized by having a gelled negative electrode added with 0.5% by weight.

[0007]

The zinc alloy of the present invention is added with indium, bismuth, gallium and magnesium, calcium, barium, beryllium, etc., as an alternative element of lead, so that the zinc alloy is more stable than that of the lead-free zinc alloy. Corrosion resistance can be increased. Although the details of the mechanism of action of each additive element in this case have not been fully clarified, it has been confirmed that hydrogen gas generation cannot be suppressed to a practical level when each element is added alone. It is considered that, due to the synergistic effect of the addition of a plurality of elements, the hydrogen overvoltage on the surface of the zinc alloy is increased, or the surface is smoothed and the surface area is reduced, so that the corrosion resistance is improved. It should be noted that the expression "lead-free" is used here because in the current general zinc refining technology, even what is called pure zinc contains 30 ppm of lead.
It is unavoidable that impurities are mixed in as impurities, and 30 pp
This is because it is technically possible, but it is considered to be disadvantageous in terms of cost.

Further, the zinc alloy powder of the present invention has a smaller gas generation amount than the lead-added zinc alloy powder and can be used as it is for a battery having a structure for releasing the generated gas. In batteries and the like, merely improving the zinc alloy composition as in the present invention cannot suppress the generation of gas at a practical level without causing liquid leakage. Therefore, by adding an indium compound as an anticorrosive agent (inhibitor), it is possible to obtain a gelled negative electrode that can be used even in a battery having a sealed structure. The details of the gas generation suppressing mechanism of the indium compound are not clear, but they have a great effect on gas generation particularly when the battery is partially discharged.

[0009]

EXAMPLES Examples of the present invention and comparative examples will be described in detail below. (Example 1) First, 0.439 parts by weight of polyacrylic acid as a gelling agent was added with 0.039 parts by weight of indium oxide (In ₂ O ₃ ) of a reagent grade or higher (based on zinc alloy powder as In conversion). 0.05% by weight) and uniformly mixed in a pot mill for 10 minutes, after which In: 0.05% by weight, Bi: 0.005% by weight, Ga: 0.01% by weight
And Mg: particle size containing 0.01 wt% 100-300μ
m zinc alloy powder (65 parts by weight), and the mixture was stirred for 5 minutes with a general-purpose mixer and uniformly mixed. Then add zinc oxide to 3.5
The mixture of the zinc alloy powder was gradually added to 35 parts by weight of an aqueous solution of 35% by weight of caustic potash dissolved in 35% by weight, and the mixture was stirred and mixed under a reduced pressure of 150 mmHg or less, and further reduced in pressure of 10 mmHg or less. The mixture was left in the state and stirred for 5 minutes to produce a uniform gelled negative electrode.

Using the gelled negative electrode thus obtained, J shown in FIG.
An IS standard LR6 type (AA) alkaline battery was assembled. In FIG. 1, reference numeral 1 denotes a bottomed cylindrical metal can that also serves as a positive electrode terminal. The metal can 1 is filled with a positive electrode mixture 2 which is pressure-molded into a cylindrical shape. The positive electrode mixture 2 is a mixture of manganese dioxide powder and carbon powder, which is housed in the metal can 1 and pressure-molded into a hollow cylinder at a predetermined pressure. In addition, the hollow portion of the positive electrode mixture 2 is filled with the gelled negative electrode 4 manufactured by the above method via the bottomed cylindrical separator 3 made of a nonwoven fabric of acetalized polyvinyl alcohol fiber. In the gelled negative electrode 4, a brass negative electrode current collector rod 5 is inserted so that the upper end portion thereof protrudes from the gelled negative electrode 4. An insulating gasket 6 made of a double annular polyamide resin is disposed on the outer peripheral surface of the protruding portion of the negative electrode current collector rod 5 and the upper inner peripheral surface of the metal can 1. Also,
A ring-shaped metal plate 7 is provided between the double annular portions of the gasket 6.
In addition, a cap-shaped metal sealing plate 8 also serving as a negative electrode terminal is arranged on the metal plate 7 so as to abut on the head of the current collecting rod 5. The opening edge of the metal can 1 is bent inward to seal the inside of the metal can 1 with the gasket 6 and the metal sealing plate 8.

(Examples 2 to 11) A JIS standard LR6 type (AA) alkaline battery was used in the same manner as in Example 1 except that the alloy composition of the zinc powder was as shown in Examples 2 to 11 in Table 1. Assembled.

(Examples 12 to 13) A JIS standard LR6 type (AA) was prepared in the same manner as in Example 1 except that the amount of indium oxide added was as shown in Examples 12 and 13 of Table 1.
Shape) Assembled alkaline battery.

Comparative Examples 1 to 12 JIS standard LR6 type (AA) alkaline batteries were used in the same manner as in Example 1 except that the alloy composition of zinc powder was as shown in Comparative Examples 1 to 12 in Table 2. Assembled.

(Comparative Examples 13 and 14) JIS standard LR6 type (AA) was prepared in the same manner as in Example 1 except that the amount of indium oxide added was as shown in Comparative Examples 13 and 14 of Table 2.
Shape) Assembled alkaline battery.

For each LR6 battery assembled as described above, the undischarged and partially discharged (2Ω 30 minutes discharge) batteries were stored at 60 ° C. for 40 days and then decomposed in water to capture gas inside the batteries. Collected results (n = 10 average values),
The 2Ω continuous discharge duration (up to 0.9V, n = 6 average values) was examined. Tables 1 and 2 show the test results of these batteries.

[0016]

[Table 1]

[0017]

[Table 2]

As is clear from Tables 1 and 2, according to Comparative Examples 4, 7 and 10, even if indium, bismuth and gallium were added alone, both undischarged and partially discharged were 60.
It can be seen that there is no effect in suppressing gas generation due to liquid leakage during storage at 40 ° C. for 40 days, but due to the synergistic effect when multiple elements are used as in Examples 1 to 13, the lead-containing zinc alloy of Comparative Example 1 is obtained. Gas generation is suppressed more than.

According to Examples 1 to 3 and Comparative Examples 2 and 3,
Indium as an additive element in a zinc alloy is very effective in suppressing gas generation when lead is not added, and when indium is not added (Comparative Example 2), even if bismuth, gallium, etc. are added, it is at a practical level. It doesn't. Moreover, even if indium is added in an amount of more than 0.1% by weight (Comparative Example 3),
There is no remarkable effect, and in terms of cost, indium is preferably 0.1% by weight or less.

It is considered that bismuth as an additional element in the zinc alloy smoothes the surface and reduces the surface area to suppress gas generation. According to Examples 1, 4, 5 and Comparative Examples 5, 6, bismuth has a large gas generation suppressing effect, but on the other hand, it seems that the heavy load discharge characteristics are adversely affected when the added amount is large, so that the gas generation suppression is suppressed. And the balance of heavy load discharge characteristics, 0.001 to 0.01
It is desirable to add in the range of weight%.

According to Examples 1, 6 and 7 and Comparative Examples 8 and 9, the effect of suppressing the gas generation by adding gallium is clear, but even if it is added in an amount of more than 0.01% by weight (Comparative Example 9 ) There is no remarkable effect, and gallium is preferably 0.01% by weight or less in terms of cost.

Examples 1, 8 to 11 and Comparative Examples 11 and 12
According to the above, it can be seen that the addition of an element such as magnesium produces a safer alkaline battery with less gas generation after partial discharge than the case of adding the three elements of indium, bismuth, and gallium. However, if the addition amount of magnesium or the like is too large, the amount of gas generated tends to be rather increased. Therefore, the total amount is preferably 0.05% by weight or less.

Examples 1, 12, 13 and Comparative Examples 13, 1
4, it is clear that the addition of indium oxide is necessary to suppress the gas generation after partial discharge to a level practical for an alkaline battery having a sealed structure.
However, adding more than 0.5% by weight in terms of indium has no outstanding effect, and in terms of cost, the amount added may be 0.5% by weight or less in terms of indium. Although not described in this example, even if an indium compound such as indium hydroxide, indium nitrate, indium chloride, or indium sulfate is added instead of indium oxide, good results can be obtained as in this example. Was given.

[0024]

As described above, the zinc-alkaline battery having the gelled negative electrode using the anticorrosive agent of the zinc alloy powder of the present invention achieves further pollution reduction of the battery that is lead-free and lead-free. Moreover, it has an excellent effect that it has less gas generation and is safe and high-performance, as compared with the case of using the leadless zinc alloy powder.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an alkaline battery according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal can, 2 ... Positive electrode mixture, 3 ... Separator, 4 ... Gel negative electrode, 5 ... Negative electrode collector rod, 6 ... Insulating gasket, 7 ... Ring-shaped metal plate, 8 ... Metal sealing plate.

Claims (1)

[Claims] 1. Indium 0.01-0.1 wt%, bismuth 0.001-0.01 wt%, gallium 0.00
1 to 0.05 wt% and 0.001 to 0.05 wt% in total of at least one selected from the group consisting of magnesium, calcium, barium, and beryllium in total, lead-free and lead-free zinc alloy powder As the negative electrode active material,
Further, as an anticorrosive agent for the zinc alloy powder, an indium compound is added in an amount of 0.005 to 0.
A zinc alkaline battery comprising a gelled negative electrode added at 5% by weight.