JPH06338317A - Zinc-alkaline battery - Google Patents

Abstract

PURPOSE:To obtain a low-polluting and safe zinc-alkaline battery having high performance by using an unamalgamated and lead-free zinc alloy powder, to which lead is not added. CONSTITUTION:A gel-like negative electrode 4 using an unamalgamated and lead-free free zinc alloy powder, which includes one kind or more of element at 0.001-0.05weight% selected from a group of indium at 0.01-0.1weight%, aluminum at 0.001-0.1weight%, beryllium and manganese and to which lead is not added, as the negative electrode active material is used. Indium compound and tetrabutylammonium hydroxide can be added to the gel-like negative electrode.

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 which is low in pollution, safe, and high in performance, which uses zinc alloy powder which is free of lead and does not contain lead.

[0002]

2. Description of the Related Art Conventionally, zinc negative alloy powder has been used as a negative electrode active material for a zinc alkaline battery 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 has been a social demand for low pollution, and a zinc alloy composition and an anticorrosive agent (inhibitor) for making the zinc alloy powder unconstrained (silver-free). As a result of such research, finally, a 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 published 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 corrosion resistance, but they are not sufficient.

Further, although it can be used for a battery having a structure for releasing generated gas, a battery having a sealed structure such as a cylindrical alkaline manganese dry battery can be produced by simply improving the zinc alloy composition. Even if the generation 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 which is lead-free and lead-free. .

[0006]

To solve the above problems, the present invention is selected from the group consisting of 0.01 to 0.1% by weight of indium, 0.001 to 0.01% by weight of aluminum, and beryllium and manganese. At least one or more of the above is used as a negative electrode active material containing 0.001 to 0.05% by weight of lead-free zinc alloy powder, and a zinc alloy powder containing an indium compound as a corrosion inhibitor for the zinc alloy powder. On the other hand, by using a gelled negative electrode in which 0.005 to 0.5% by weight in terms of indium and / or 0.0001 to 0.05% by weight of tetrabutylammonium hydroxide is added to the zinc alloy powder, It is a pollution-free, safe, and high-performance zinc alkaline battery.

[0007]

In the zinc alloy of the present invention, by adding indium, aluminum, beryllium, manganese or the like as an alternative element of lead, the corrosion resistance at the time of non-discharge can be improved as compared with the unblended / lead-added zinc alloy. it can. 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. In addition, what is expressed here as lead-free is that, in the current general zinc refining technology, it is unavoidable that lead is mixed in as an impurity by about 30 ppm even if it is said to be pure zinc, and it is set to 30 ppm or less. 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 practicable level without causing liquid leakage.

Therefore, by adding an indium compound and / or tetrabutylammonium hydroxide 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. Of these, the details of the gas generation suppressing mechanism of indium compounds are not clear, but they have a great effect on gas generation when the battery is partially discharged, while tetrabutylammonium hydroxide adheres to the surface of the zinc alloy powder. The self-discharge is suppressed to further suppress the gas generation in the undischarged state, and when impurities are mixed in the gelled negative electrode, the chance of contact between zinc powder and impurities is reduced, and the risk of gas generation due to impurities. Can be lowered.

[0010]

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, and then added with a particle size of 100 including In: 0.05% by weight, Al: 0.003% by weight, and Be: 0.02% by weight. ~ 300 μm zinc alloy powder 65
In addition to the parts by weight, the mixture was stirred for 5 minutes in a general-purpose mixing period and uniformly mixed. Then, 0.00065 parts by weight of tetrabutylammonium hydroxide was added to 35 parts by weight of a 35% by weight aqueous solution of potassium hydroxide in which 3.5% by weight of zinc oxide was dissolved.
After mixing and stirring for 1 minute to sufficiently disperse, the mixture of the zinc alloy powder is gradually added over 4 minutes, and
Stir and mix under reduced pressure of 50 mmHg or less, then 1
The pressure was reduced to 0 mmHg or less and stirred for 5 minutes to produce a uniform gelled negative electrode.

Using the gelled negative electrode thus obtained, the 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 pressed 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. A brass negative electrode current collector rod 5 is mounted in the gel negative electrode 4 such that the upper end of the negative electrode current collector rod 5 projects from the gel 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 8) The alloy composition of zinc powder is shown in Table 1.
JI in the same manner as in Example 1 except that it is as shown in FIG.
An S standard LR6 type (AA) alkaline battery was assembled.

[0013]

[Table 1]

(Examples 9 to 10) A JIS standard LR6 type (AA) alkaline battery was assembled in the same manner as in Example 1 except that the added amount of indium oxide was as shown in Table 1.

(Examples 11 to 12) JIS standard LR6 type (AA) was prepared in the same manner as in Example 1 except that the addition amount of tetrabutylammonium hydroxide was as shown in Table 1.
Shape) Assembled alkaline battery.

(Comparative Examples 1 to 9) The alloy composition of zinc powder is shown in Table 3.
JI in the same manner as in Example 1 except that it is as shown in FIG.
An S standard LR6 type (AA) alkaline battery was assembled.

[0017]

[Table 3]

Comparative Examples 10 to 14 JIS standard LR6 type (AA) alkaline batteries were used in the same manner as in Example 1 except that the amounts of indium oxide and tetrabutylammonium hydroxide added were as shown in Table 3. Assembled.

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),
2Ω continuous discharge duration (up to 0.9V, n = 6 average value) and 1.2kΩ continuous discharge single life occurrence rate (n = 5
0) was investigated. Tables 2 and 4 show the test results of these batteries.

[0020]

[Table 2]

[0021]

[Table 4]

As is clear from Tables 2 and 4, according to Comparative Examples 4 and 7, even if indium and aluminum were added alone, both undischarged and partial discharge leaked at 60 ° C. for 40 days. However, it is understood that there is no effect in suppressing the gas generation, but when the multi-element system is used as in Examples 1 to 12, the gas generation is suppressed more than the lead-containing zinc alloy of Comparative Example 1 due to the synergistic effect.

According to Examples 1-3 and Comparative Examples 2-3,
Indium as an additive element in the 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 aluminum or the like is added, it becomes a practical level. Don't 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.

According to Examples 1, 4 and 5 and Comparative Examples 5 and 6, aluminum has a great effect of suppressing gas generation, but if the amount of addition is large, it is feared that a short life is likely to occur at the time of light load discharge. Considering the balance between suppression of gas generation and light load discharge characteristics, it is desirable to add in the range of 0.001 to 0.01% by weight.

According to Examples 1, 6 to 8 and Comparative Examples 8 and 9, adding an element such as beryllium produces less gas after partial discharge than adding two elements of indium and aluminum. It can be seen that a safer alkaline battery can be obtained. However, if the addition amount of beryllium or the like is too large, the gas generation tends to increase, so
It is preferably 0.05% by weight or less. Further, even when two kinds of beryllium and manganese were added in appropriate amounts, similarly good results were obtained.

Examples 1, 9, 10 and Comparative Examples 10-12
According to the above, 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 has no remarkable effect, and from the viewpoint of cost, the addition amount of 0.5% by weight or less is sufficient. Although not described in this example, good results can be obtained similarly to this example even when an indium compound such as indium hydroxide, indium nitrate, indium chloride, or indium sulfate is added instead of indium oxide. Was given.

Examples 1, 11, 12 and Comparative Examples 13, 1
According to 4, it is found that addition of tetrabutylammonium hydroxide is effective in suppressing gas generation in an undischarged state.
If it is added in an amount of more than 0.05% by weight, the impedance of the gelled negative electrode rises, and it seems that the heavy load discharge is adversely affected. Therefore, the addition amount of 0.05% by weight or less is sufficient.

[0028]

As described above, the zinc-alkaline battery having the gelled negative electrode using the zinc alloy powder and the anticorrosive of the present invention achieves further pollution reduction of the battery which is free of lead and containing no lead. Moreover, it is excellent in that it produces less gas and is safer and has higher performance than the case of using the leadless zinc alloy powder.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an LR6 type alkaline battery according to the present invention.

[Explanation of symbols]

 4 Gelled negative electrode 5 Current collector rod 6 Gasket

Claims (3)

[Claims] 1. At least one selected from the group consisting of 0.01 to 0.1% by weight of indium, 0.001 to 0.01% by weight of aluminum, and beryllium and manganese is added to 0.001 to 0. A zinc-alkaline battery having a gelled negative electrode in which a lead-free zinc alloy powder containing 0.05% by weight is used as a negative electrode active material. 2. An indium compound as an anticorrosive agent for zinc alloy powder is added to the gelled negative electrode in an amount of 0.005 to 0.5% by weight in terms of indium with respect to the zinc alloy powder. Zinc alkaline battery. 3. The gelled negative electrode is added with 0.0001 to 0.05% by weight of tetrabutylammonium hydroxide as an anticorrosive agent for zinc alloy powder with respect to the zinc alloy powder. The zinc alkaline battery according to claim 2.