JPH0955206A - Zinc-alkali battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a zinc-alkali battery with no environmental pollution and high safety by retarding gas evolution without adding mercury and lead. SOLUTION: In a zinc-alkali battery, zinc alloy powder containing 0.01-0.1wt.% indium, 0.001-0.01wt.% aluminum, 0.001-0.01wt.% bismuth, 0.001-0.05wt.% titanium, and a total of 0.001-0.05wt.% at least one element selected from the group comprising lithium, sodium, and potassium is used as a negative active material. In addition, 0.05-0.5wt.% indium compound in indium equivalent is added to the zinc alloy powder as the inhibitor of the zinc alloy powder. Thereby, the internal gas evolution of the battery is retarded without adding mercury and lead.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, zinc hydride 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. However, in recent years, environmental pollution due to used batteries has come to be a problem, and it has become a social demand to reduce pollution, and zinc alloy powder is used to make zinc alloy powder non-silver (anhydrous). Research on the composition and anticorrosive agent (inhibitor) has been advanced, and finally, a gelled negative electrode for a mercury-free alkaline battery without any practical problems has been developed.

[0003]

However, in the non-melonized zinc alloy powder that has been put to practical use in mercury-free alkaline batteries, lead, which is a harmful substance like mercury, is contained in order to suppress the generation of hydrogen gas. Due to the addition of 100 ppm, there is an increasing demand for a mercury-free alkaline battery using a lead-free zinc alloy powder.

[0004] By the way, there have been many patent publications concerning zinc alloys for zinc-alkaline batteries to which lead has not been added so far, such as JP-A-63-133450 and JP-A-2-194103. Some of them can be expected to have some corrosion resistance, but they are not enough. Further, although it can be used for a battery having a structure for releasing generated gas, many batteries having a sealed structure such as a cylindrical alkaline manganese dry battery cannot be put to practical use. Furthermore, even if the generation of gas during non-discharge can be suppressed, the generation of gas after partial discharge cannot be suppressed, so that a 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, the present invention provides a zinc alkaline battery in which 0.01 to 0.1% by weight of indium and 0.001 to 0.001 of aluminum are used.
0.01% by weight, 0.001 to 0.01% by weight of bismuth, 0.001 to 0.05% by weight of titanium, and at least one selected from the group consisting of lithium, sodium and potassium in a total amount of 0.001 to 0.001. A zinc alloy powder containing 0.05 wt% is used as a negative electrode active material, and an indium compound is added as an anticorrosive agent for the zinc alloy powder in an amount of 0.005 to 0.5 wt% in terms of indium with respect to the zinc alloy powder. And

In the present invention, by adding indium, aluminum, bismuth, titanium and lithium, sodium, potassium, etc. as an alternative element to lead in the zinc alloy, corrosion resistance at the time of non-discharge is improved as compared with the non-free lead-containing zinc alloy. Can be increased. The details of the action mechanism of each additive element in this case are not fully understood, but 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 the corrosion resistance is improved by increasing the hydrogen overvoltage on the surface of the zinc alloy by the synergistic effect of the addition of a plurality of elements, or by reducing the surface area by smoothing the surface. The term “lead-free” is used here because it is unavoidable that lead is mixed as an impurity of about 30 ppm even in what is called pure zinc in the current general zinc refining technology.
It does not mean that the lead content is zero. Although it is technically possible to set it to 30 ppm or less, it is considered to be disadvantageous in terms of cost.

When the above zinc alloy powder is used, the amount of gas generated in the battery is smaller than that in the case of using the conventional lead-added zinc alloy powder, and a zinc alkaline battery with low pollution and high safety can be obtained. However, although a battery having a structure that allows the generated gas to escape is preferable, a cylindrical alkaline manganese battery having a sealed structure is not always sufficient, and further improvement is required. In that case, the intended purpose can be achieved by adding an indium compound as a corrosion inhibitor (inhibitor) to the zinc alloy powder. When an indium compound is added as an anticorrosive agent, it can be used even in a battery having a sealed structure. Although the mechanism for suppressing the gas generation of the indium compound is not clear, it has a great effect on the gas generation particularly when the battery is partially discharged.

If the amount of the indium compound added to the zinc alloy powder is less than 0.005% in terms of indium, it is ineffective, and if it is more than 0.5%, there is no remarkable effect. 0.005 to 0.
5% is appropriate.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. (Example 1) First, 0.4 parts by weight of polyacrylic acid as a gelling agent was added to indium oxide (I
n ₂ O ₃ ) was added in an amount of 0.039 parts by weight (0.05% by weight based on zinc alloy powder in terms of In), and 1
After uniformly mixing for 0 minutes, In: 0.05 wt%, Al: 0.005 wt%, Bi: 0.005 wt%, Ti: 0.005 wt% and K: 0.01 wt%
Was added to 65 parts by weight of a zinc alloy powder having a particle diameter of 100 to 300 μm, and the mixture was stirred for 5 minutes with a general-purpose mixer and uniformly mixed. 35% by weight of zinc oxide dissolved in 3.5% by weight
The mixture of the zinc alloy powder was gradually added to 35 parts by weight of a caustic potash aqueous solution having a concentration of 4 minutes, and
Stir and mix under a reduced pressure of 0 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 mixed in a metal can 1
It is housed inside and pressure-molded into a hollow cylinder at a predetermined pressure. The hollow portion of the positive electrode mixture 2 is filled with the gelled negative electrode 4 manufactured by the above-described method via a 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 provided on the outer peripheral surface of the protruding portion of the negative electrode current collecting rod 5 and the upper inner peripheral surface of the metal can 1. A ring-shaped metal plate 7 is disposed between the double annular portions of the gasket 6, and a cap-shaped metal sealing plate 8 also serving as a negative electrode terminal is provided on the metal plate 7 so as to contact the head of the current collecting rod 5. It is arranged to touch. 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 13) JI was prepared in the same manner as in Example 1 except that the alloy composition of zinc powder was as shown in the table.
An S standard LR6 type (AA) alkaline battery was assembled.

(Examples 14 to 15) 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 the table.

Comparative Examples 1 to 15 JI was prepared in the same manner as in Example 1 except that the alloy composition of the zinc powder was as shown in the table.
An S standard LR6 type (AA) alkaline battery was assembled.

Comparative Examples 16 to 17 JIS standard LR6 (AA) alkaline batteries were assembled in the same manner as in Example 1 except that the amount of indium oxide added was as shown in the table.

Each LR6 type battery assembled as described above was undischarged and partially discharged (2Ω 30 minutes discharge)
After storing the subsequent battery at 60 ° C. for 40 days, the battery was decomposed in water to collect the gas inside the battery, and the gas generation amount was examined (n =
10 average values). In addition, the duration of continuous discharge of 2Ω was examined (n = 10 average values). The results are shown in Table 1.

[0017]

[Table 1]

As is clear from Table 1, Comparative Examples 4, 7,
According to 10 and 13, indium, aluminum,
It can be seen that even if bismuth and titanium are added alone, both undischarged and partial discharge are leaked by storage at 60 ° C. for 40 days, which is not effective in suppressing gas generation. With a multi-element system, the synergistic effect suppresses gas generation more than the lead-containing zinc alloy of Comparative Example 1.

According to Examples 1 to 3 and Comparative Examples 2 and 3, indium as an additive element in the zinc alloy is very effective in suppressing gas generation when lead is not added, and indium is not added (comparative example). Even if 2) and aluminum, bismuth, titanium, etc. are added, it does not reach a practical level. Further, 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, 5 and Comparative Examples 5, 6, aluminum has a great effect of suppressing gas generation. However, although not shown in the table, the rate of occurrence of short life at 1.2 kΩ continuous discharge was 24% (n =
It may have a bad influence on the light load discharge characteristics such as a high value (in 50 pieces), so in consideration of the balance between gas generation suppression and the light load discharge characteristics, 0.001 to 0.01% by weight is added. Is desirable.

According to Examples 1, 6 and 7 and Comparative Examples 8 and 9, the gas generation suppressing effect by the addition of bismuth is clear, but the addition amount is too large (Comparative Example 9) and 2
Since the heavy load discharge characteristics such as Ω continuous discharge are deteriorated, the addition amount of bismuth is preferably 0.01% by weight or less.

Examples 1, 8, 9 and Comparative Examples 11, 12
According to the above, when titanium is added, the gas generation suppressing effect is apparent, but even if it is added in an amount of more than 0.05% by weight (Comparative Example 12), there is no remarkable effect, and the addition amount of titanium is 0.1%.
It may be up to 05% by weight.

Examples 1, 10 to 13 and Comparative Example 14,
15, it is found that the addition of lithium, sodium, potassium or the like has a great effect of suppressing gas generation in an undischarged state, but the addition of more than 0.05% by weight (Comparative Example 15) has a remarkable effect. However, the addition amount may be 0.05% by weight or less.

Examples 1, 14, 15 and Comparative Example 16,
17, it is found that the addition of indium oxide is necessary to suppress the gas generation after partial discharge to a level that is practical for an alkaline battery having a sealed structure. However, even if added in excess of 0.5 wt% in terms of indium, there is no remarkable effect, and in terms of cost, the amount added may be 0.5 wt% or less in terms of indium. In addition,
Although not described in this example, even if an indium compound such as indium hydroxide, indium nitrate, indium chloride, or indium sulfate was added instead of indium oxide, good results were obtained as in this example. .

[0025]

As described above, the zinc-alkaline battery of the present invention can suppress the generation of gas while being free of lead and containing no lead. Therefore, according to the present invention, a zinc alkaline battery with low pollution and high safety can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of a zinc alkaline battery according to one 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.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Seiichi Hikata 3-4-10 Minami-Shinagawa, Shinagawa-ku, Tokyo Inside Toshiba Battery Co., Ltd.

Claims (1)

[Claims] 1. Indium 0.01 to 0.1% by weight, aluminum 0.001 to 0.01% by weight, bismuth 0.1%.
001 to 0.01% by weight, titanium 0.001 to 0.05
0.001% by weight and at least one selected from the group consisting of lithium, sodium, and potassium
~ 0.05% by weight of zinc alloy powder as a negative electrode active material, and an indium compound as a corrosion inhibitor of zinc alloy powder 0.005 in terms of indium with respect to zinc alloy powder.
A zinc-alkaline battery characterized by being added by 0.5 wt%.