JPH06338319A - 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 In. at 0.01-0.1weight%, BiO. at 0.001-0.01weight%, AlO. at 0.001-0.01weight%, GaO. at 0.001-0.01weight%, Ca, Sr, and Ba and to which lead is not added, as the negative electrode active material is used. Indium compound and fluorine group surface active agent can be added to the gel-like negative electrode 4.

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, it has become a social demand to reduce pollution, and a zinc alloy composition and an anticorrosive agent (inhibitor) are used to make zinc alloy powder unconstrained (silver-free). ) And the like, and 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 publicly disclosed zinc alloys for lead-free zinc-alkaline batteries, such as JP-A-63-133450 and JP-A-2-194103, and some of them have been disclosed. 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 is an urgent need to develop a zinc alloy composition that generates less gas and a gelled negative electrode that can be applied 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]

In order to solve the above-mentioned problems, the present invention provides 0.01 to 0.1% by weight of indium, 0.001 to 0.01% by weight of bismuth, 0.0 of aluminum.
01-0.01 wt%, gallium 0.001-0.01
%, And at least one selected from the group consisting of calcium, strontium, and barium, 0.0
0.1 to 0.05% by weight of zinc alloy powder containing no lead and no lead was used as a negative electrode active material, and an indium compound was 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. ˜0.5% by weight, and / or fluorine-based surfactant is 0.0 with respect to the zinc alloy powder.
By using a gelled negative electrode added with 005 to 0.01% by weight, a low-pollution, safe and high-performance zinc alkaline battery is realized.

[0007]

The zinc alloy of the present invention is added with indium, bismuth, aluminum, gallium and calcium, strontium, barium, etc., as an alternative element of lead, so that the zinc alloy in the undischarged state is better than that of the unalloyed lead-added 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 what is expressed here as lead-free is that even if what is said to be pure zinc in the current general zinc refining technology, 30 p
It is unavoidable that impurities are mixed in as much as pm.
This is because it can be 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 a fluorine-based surfactant as an anticorrosive agent (inhibitor), a gelled negative electrode that can be used even in a battery having a sealed structure can be obtained. Of these, the indium compound has a great effect on gas generation when the battery is partially discharged, while the details of the gas generation suppression mechanism are not clear, while the fluorine-based surfactant 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 mixed with In: 0.05% by weight, Bi: 0.01% by weight, Al: 0.003% by weight, Ga: 0.01 Wt% and Ba: 0.005 wt% and added to 65 parts by weight of a zinc alloy powder having a particle size of 100 to 300 μm, and stirred for 5 minutes with a general-purpose mixer to uniformly mix. 35% by weight of zinc oxide dissolved in 3.5% by weight
To 35 parts by weight of a caustic potash aqueous solution having a concentration of 0.0009975 parts by weight of a fluorine-based surfactant (0.1% with respect to zinc alloy powder).
0015% by weight) and mixed and stirred for 10 minutes to sufficiently disperse, then the mixture of the zinc alloy powder is gradually added over 4 minutes, and the mixture is stirred and mixed under a reduced pressure of 150 mmHg or less, and The pressure was reduced to 10 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. 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 13) J was carried out in the same manner as in Example 1 except that the alloy composition of the zinc powder was as shown in Table 1.
An IS standard LR6 type (AA) alkaline battery was assembled.

[0013]

[Table 1]

(Examples 14 to 15) JIS standard LR6 type (AA) alkaline batteries were assembled in the same manner as in Example 1 except that the added amount of indium oxide was as shown in Table 1.

(Examples 16 to 17) A JIS standard LR6 type (AA) alkaline battery was assembled in the same manner as in Example 1 except that the amount of the fluorine-based surfactant added was as shown in Table 1. .

(Comparative Examples 1 to 15) J was carried out in the same manner as in Example 1 except that the alloy composition of the zinc powder was as shown in Table 3.
An IS standard LR6 type (AA) alkaline battery was assembled.

[0017]

[Table 3]

(Comparative Examples 16 to 20) JIS standard LR6 type (AA) alkaline batteries were prepared in the same manner as in Example 1 except that the amounts of indium oxide and fluorine-based surfactant 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, 7, 10 and 13, even if indium, bismuth, aluminum and gallium were added alone, both undischarged and partially discharged were 60 ° C. It can be seen that liquid is leaked after 40 days of storage and there is no effect in suppressing gas generation. However, when a multi-element system is used as in Examples 1 to 17, a synergistic effect results in a lead-containing zinc alloy of Comparative Example 1. Also, gas generation is suppressed.

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 is practically used even if indium is not added (Comparative Example 2) and bismuth, aluminum, gallium, etc. are added. Not at a possible level. 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, 5 and Comparative Examples 5, 6, bismuth as an additive element in the zinc alloy is considered to suppress the gas generation by smoothing the surface and reducing the surface area. On the other hand, it seems that the heavy load discharge characteristics are adversely affected when the added amount is large, and therefore, considering the balance between the gas generation suppression and the heavy load discharge characteristics,
It is desirable to add in the range of 001 to 0.01% by weight.

According to Examples 1, 6 and 7 and Comparative Examples 8 and 9, although aluminum has a great effect of suppressing gas generation, there is a concern that a large amount of aluminum tends to cause a short life at 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, 8 and 9 and Comparative Examples 11 and 12, the gas generation suppressing effect by the addition of gallium is clear, but even if it is added in an amount of more than 0.01% by weight (Comparative Example 12). ), There is no noticeable effect, and 0.01% by weight or less of gallium is preferable from the viewpoint of cost.

Examples 1, 10 to 13 and Comparative Examples 14 and 1
5, it can be seen that the addition of an element such as barium produces a safer alkaline battery with less gas generation after partial discharge than the case of adding the four elements of indium, bismuth, aluminum and gallium. However, if the addition amount of barium or the like is too large, the amount of gas generated tends to increase, so the content is preferably 0.05% by weight or less. Although not described in this example, even if two or more kinds of barium, calcium and strontium were added in an appropriate amount, good results were obtained as in this example.

Examples 1, 14-17 and Comparative Examples 16-2
According to 0, 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 embodiment, even if an indium compound such as indium hydroxide, indium nitrate, indium chloride or indium sulfate is added instead of indium oxide, the same effect as in this embodiment is obtained. The results were obtained. Also, it can be seen that the addition of the fluorine-based surfactant is effective in suppressing the gas generation in the undischarged state, but if added in an amount of more than 0.01% by weight, the impedance of the gelled negative electrode will increase, resulting in heavy load discharge. Since it seems to have an adverse effect, the amount added may be 0.01% by weight or less.

[0030]

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. Indium 0.01 to 0.1% by weight, bismuth 0.001 to 0.01% by weight, aluminum 0.
001 to 0.01% by weight, gallium 0.001 to 0.0
1% by weight and at least one selected from the group consisting of calcium, strontium and barium,
A zinc-alkaline battery having a gelled negative electrode in which a lead-free zinc alloy powder containing 001 to 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. A gelling negative electrode containing a fluorine-based surfactant as an anticorrosive agent for zinc alloy powder in an amount of 0.1.
The zinc alkaline battery according to claim 1 or 2, wherein the zinc alkaline battery is added in an amount of 0005 to 0.01% by weight.