JPH053032A - Alkaline storage battery - Google Patents

Abstract

PURPOSE:To suppress an internal pressure due to the generation of hydrogen gas during storage so as to enhance its discharge performance by providing a gelnegative electrode, in which the corrosion of non-amalgamated zinc alloy powders being prevented, in an alkaline battery. CONSTITUTION:An alkaline battery of this invention contains a gel negative electrode 4 comprising zinc allay powders and an alkaline electrolyte. The gel negative electrode 4 contains an anticorrosives for the zinc alloy powders. The anticorrosives contain indium compounds, for example an indium oxide being contained in an amount of 0.01 to 0.1wt.% in terms of only indium relative to the zinc alloy powders. Furthermore, as the anticorrosives, an alkyl benzene sulfate, in which the number-of-carbon of an alkyl group being equal to and less than thirty five, or its salt neutralized by an alkaline metal, for example alkyl benzene potassium sulfate, the number-of-carbon of which being nine, is contained ranging from 0.01 to 0.1wt% therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anticorrosive agent for zinc alloy powder, which is a negative electrode active material for alkaline batteries.

[0002]

2. Description of the Related Art Conventionally, alkaline batteries have used a gelled negative electrode obtained by gelling zinc powder as an active material and an alkaline electrolyte. In such an alkaline battery, when the zinc powder in the gelled negative electrode is corroded by the alkaline electrolyte, hydrogen gas is generated to increase the internal pressure or decrease the battery capacity. The corrosion of the zinc powder is mainly due to the low hydrogen overvoltage of the zinc powder. Therefore, the hydrogen overvoltage of the zinc powder is increased by subjecting the surface of the zinc powder to an amalgamation treatment with mercury.

However, in recent years, it has been desired to reduce the amount of mercury in the battery from the viewpoint of environmental pollution. Therefore, various metal elements (eg, lead, indium, aluminum, gallium, etc.) can be used as the negative electrode active material having sufficient corrosion resistance even if the amount of mercury used for the grading treatment is not small.
Zinc alloy powder having a composition in which is added to zinc has come to be used.

However, when the zinc alloy powder having the above composition is not subjected to the selective treatment, sufficient corrosion resistance to the electrolytic solution cannot be obtained. Therefore, in an alkaline battery using the zinc alloy powder as a negative electrode active material, There is a problem that it is not possible to suppress an increase in internal pressure due to generation of hydrogen gas during storage.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in order to solve the conventional problems, and is provided with a gelled negative electrode that sufficiently prevents corrosion of zinc alloy powder that has not been subjected to grading treatment, and is stored. It is intended to provide an alkaline battery in which an increase in internal pressure due to generation of hydrogen gas in the inside is suppressed.

[0006]

The present invention provides an alkaline battery having a gelled negative electrode containing zinc alloy powder as an active material and an alkaline electrolyte, wherein the gelled negative electrode is an anticorrosive agent for the zinc alloy powder. As the (a) indium compound, the indium compound is converted to zinc alloy powder in an amount of 0.
01 to 1.0% by weight, and (b) the alkyl group has 3 carbon atoms
Alkyl benzene sulfonic acid with 5 or less

[0007]

[Chemical 1]

Alternatively, at least one selected from the group consisting of salts obtained by neutralizing this with an alkali metal is contained in an amount of 0.01 to 1.0% by weight based on the zinc alloy powder. It is an alkaline battery.

The zinc alloy powder is not subjected to a grading treatment, and its composition is at least one of lead, indium, aluminum, gallium, cadmium, thallium, nickel, cobalt, bismuth, and tin. Mention may be made of a composition in which the seed is added to zinc. The particle size of the zinc alloy powder is preferably in the range of 75 to 300 μm. The reason for this is that if the particle size is less than 75 μm, the specific surface area increases and the contact area with the electrolytic solution increases, so the amount of hydrogen gas generated during storage may increase. On the other hand, if the particle size exceeds 300 μm, the density of the zinc alloy powder occupying the gelled negative electrode may decrease, which may lead to a decrease in battery capacity.

Examples of the alkaline electrolyte include potassium hydroxide aqueous solution and sodium hydroxide aqueous solution. If necessary, zinc oxide may be dissolved in the alkaline electrolyte at 8% by weight or less.

Examples of the indium compound of the present invention (hereinafter referred to as anticorrosion agent a) include, for example, indium oxide (In ₂ O).
₃ ), indium hydroxide (In (OH) ₃ ), and the like. These may be used alone or as a mixture of two or more. The reason why the content of the anticorrosive agent a is limited is that if the content is less than 0.01% by weight, the anticorrosive effect of the anticorrosive agent a on the zinc alloy powder is not sufficiently exhibited. On the other hand, if the content exceeds 1.0% by weight, hydrogen gas is generated during storage. It is considered that this is because the concentration of indium ions in the alkaline electrolyte was increased and metallic indium was precipitated in the gelled negative electrode in a floating state, and the metallic indium was oxidized during storage.

At least one compound selected from the group consisting of an alkylbenzenesulfonic acid having an alkyl group of 35 or less carbon atoms of the present invention, or a salt obtained by neutralizing the alkylbenzenesulfonic acid with an alkali metal (hereinafter referred to as an anticorrosive agent b). Examples of the alkali metal constituting the alkali metal salt of the unfunctionalized functional group in () include potassium and sodium. The anticorrosive b may be used alone or as a mixture of two or more.
The reason for limiting the content of the anticorrosion agent b is that if the content is less than 0.01% by weight, the anticorrosion effect of the anticorrosion agent b on the zinc alloy powder is not sufficiently exhibited. on the other hand,
If the content exceeds 1.0% by weight, the coating film of the anticorrosive agent b formed on the surface of the zinc alloy powder becomes too thick, or the excessive anticorrosive agent b interferes with the discharge reaction, so that the discharge performance is deteriorated. Discharge duration becomes shorter.

The gelled negative electrode of the present invention can be prepared, for example, by the following method. First, the anticorrosive agent a is uniformly mixed with a gelling agent such as carboxymethyl cellulose, polyacrylic acid, or sodium polyacrylate, and this mixture is further uniformly mixed with the zinc alloy powder.

Then, the mixture of the anticorrosive agent a, the gelling agent, and the zinc alloy powder is added to an alkaline electrolyte solution in which the anticorrosive agent b is dissolved or dispersed in advance, and the mixture is stirred and mixed under reduced pressure to form a gel. Adjust the negative electrode. In addition, it is desirable that the depressurizing condition at the time of mixing should be an absolute pressure of 500 mmHg or less at the initial stage of mixing and a pressure of 300 mmHg at the latter stage of mixing from the viewpoint of sufficiently degassing air and the like in the mixture. In the step of adjusting the gelled negative electrode, it is desirable to add 50 to 80 parts by weight of the zinc alloy powder, 20 to 50 parts by weight of the alkaline electrolyte, and 0.3 to 1.5 parts by weight of the gelling agent. ..

Further, in the step of preparing the gelled negative electrode described above, an operation of dissolving or dispersing the anticorrosive agent b in the alkaline electrolytic solution was carried out in order to contain the anticorrosive agent b. Any one of the following operations 1 to 3 may be performed. 1 The anticorrosive agent b is attached to the zinc powder alloy in advance. 2 When the mixture of the anticorrosive agent a, the gelling agent and the zinc alloy powder is mixed with the alkaline electrolyte, the anticorrosive agent b
Is added. Anticorrosive b in the separator incorporated in the battery
Or the electrolytic solution holding material made of a nonwoven fabric such as cellulose or polyvinyl compound, which is incorporated as necessary, is impregnated with the anticorrosive agent b.

In the alkaline battery according to the present invention, a positive electrode mixture, a separator and the like are incorporated together with the gelled negative electrode. As the active material of the positive electrode mixture, for example, manganese dioxide, silver oxide, oxygen, nickel oxyhydroxide or the like is used. The separator is made of non-woven fabric or the like. Further, in a button type alkaline battery or the like, an electrolyte holding material or the like is usually incorporated.

[0017]

According to the present invention, in an alkaline battery comprising a gelled negative electrode containing an alkaline electrolyte together with a zinc alloy powder which is not subjected to a denaturation treatment as an active material, the gelled negative electrode is an indium compound. The agent a is 0.01 to 1.0 wt% in terms of indium with respect to the zinc alloy powder, and the anticorrosive agent b represented by the general formula (I) is 0.01 to 1 with respect to the zinc alloy powder. By containing 0.0% by weight, a gelled negative electrode in which the corrosion of the zinc alloy powder is sufficiently prevented can be obtained.

That is, a part of the anticorrosive agent a which is an indium compound is dissolved in the alkaline electrolyte to become indium ions. It is considered that this indium ion is deposited as metal indium or an indium compound on the surface of the zinc alloy powder by the redox reaction, so that the hydrogen overvoltage of the zinc alloy powder can be increased and the anticorrosion effect can be exhibited.

Further, since the anticorrosive agent b is favorably adsorbed on the surface of the zinc alloy powder due to its hydrophilic group, it is possible to form a coating film on the zinc alloy powder to prevent its corrosion. Due to the interaction between the anticorrosion agent a and the anticorrosion agent b, it is possible to obtain the gelled negative electrode in which the corrosion of the zinc alloy powder not subjected to the denaturing treatment is sufficiently prevented. As a result, by using such a gelled negative electrode, it is possible to suppress an increase in internal pressure that accompanies the generation of hydrogen gas during storage, and it is possible to obtain a high-performance alkaline battery that prevents leakage of the electrolytic solution and battery rupture.

[0020]

EXAMPLES Examples of the present invention will be described in detail below. Example 1 First, to 0.6 part by weight of polyacrylic acid as a gelling agent, the amount of indium oxide shown in Table 1 below was added as an anticorrosion agent a, and mixed uniformly in a pot mill for 10 minutes. This mixture is not grained 100-300 μm
65 parts by weight of zinc alloy powder (0.05% by weight of Pb, 0.05% by weight of A, 0.02% by weight of In, and 0.01% by weight of Ga in zinc) in a general-purpose mixer for 5 minutes. Mix evenly.

Next, the amount of potassium alkylbenzene sulfonate shown in Table 1 was dissolved / dispersed as an anticorrosive agent b, and 3.5% by weight of zinc oxide was dissolved in 35% by weight.
35 parts by weight of a concentrated potassium hydroxide aqueous solution is placed in the mixer. While gradually adding the mixture of the polyacrylic acid, indium oxide, and zinc alloy powder to this mixer over 4 minutes, stirring and mixing under a reduced pressure of absolute pressure of 150 mmHg or less, and further mixing at an absolute pressure of 10 mmHg or less. A uniform gelled negative electrode is obtained by stirring and mixing under reduced pressure for 5 minutes.

Using the gelled negative electrode thus obtained, J shown in FIG.
An IS standard LR6 type (size 6) alkaline battery was assembled. That is, in the figure, 1 is 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.

The hollow portion of the positive electrode mixture 2 is filled with the gelled negative electrode 4 obtained by the above method via a bottomed cylindrical separator 3 made of a nonwoven fabric of acetalized polyvinyl alcohol fiber. A negative electrode current collector 5 made of brass is inserted into the gelled negative electrode 4 such that the upper end of the negative electrode current collector 5 projects from the negative electrode 4. On the outer peripheral surface of the protruding portion of the negative electrode collector rod 5 and the inner peripheral surface of the upper portion of the metal can 1, an insulating gasket 6 made of a polyamide resin having a double annular portion is provided. A ring-shaped metal plate 17 is arranged 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 at the head of the collector rod 5. Is arranged so as to abut. And the metal can 1
The inside of the metal can 1 is sealed by the gasket 6 and the metal sealing plate 8 by bending the opening edge of the inside.

Examples 2 and 3 and Comparative Examples 1 and 2 Alkaline batteries were produced in the same manner as in Example 1 except that the respective amounts of potassium alkylbenzenesulfonate shown in Table 1 below were added. Comparative Example 3 An alkaline battery was produced in the same manner as in Example 1 except that potassium alkylbenzene sulfonate was not added.

Examples 4 and 5 and Comparative Examples 4 and 5 Alkaline batteries were prepared in the same manner as in Example 1 except that the amounts of indium oxide shown in Table 1 were blended. Comparative Example 6 An alkaline battery was produced in the same manner as in Example 1 except that indium oxide was not added. Examples 6 to 9 and Comparative Example 7 An alkaline battery was produced in the same manner as in Example 1 except that potassium alkylbenzenesulfonate having the carbon number of the alkyl group as shown in Table 1 was blended.

For each of the alkaline batteries of Examples 1 to 9 and Comparative Examples 1 to 7, 10 samples were used, a load resistance of 10Ω was connected, and continuous discharge was performed at 20 ° C. until a final voltage of 0.9 V. The discharge connection time was measured and the average value was calculated. In addition, 20 samples each were stored in a constant temperature bath at 60 ° C., and 10 samples were taken out after 1 month and 3 months, and these were decomposed in water to collect hydrogen gas in the battery, The amount of hydrogen gas generated during storage was measured and the average value was calculated. The results are also shown in Table 1 below.

[0027]

[Table 1]

In Table 1, * 1 is the weight% of zinc alloy powder in terms of indium, and * 2 is the weight% of zinc alloy powder.

As is clear from Table 1, the alkaline batteries of Examples 1 to 9 produced less hydrogen gas during storage than the alkaline batteries of Comparative Examples 1 to 7, and contained the zinc alloy powder of the gelled negative electrode. It can be seen that corrosion is sufficiently prevented. Moreover, it can be seen that the discharge duration is long and the discharge performance is good. This is because the anticorrosive agent a and the anticorrosive agent b are used together in an appropriate amount as the anticorrosive agent for the zinc alloy powder of the gelled negative electrode.

In the alkaline battery of Comparative Example 7, since the alkyl group of potassium alkylbenzene sulfonate has a large carbon number of 40, the balance between the hydrophilic group and the hydrophobic group is lost and the surface of the zinc alloy powder is It becomes difficult to adsorb to. As a result, potassium alkylbenzene sulfonate in the electrolytic solution interferes with the discharge reaction and shortens the discharge duration, and it is not possible to sufficiently prevent the corrosion of the zinc alloy powder in the gelled negative electrode, resulting in an amount of hydrogen gas generated during storage. Tends to increase.

[0031]

As described above in detail, according to the present invention, the gelled negative electrode is provided which is capable of sufficiently preventing the corrosion of the zinc alloy powder which has not been subjected to the denaturation treatment, and suppresses the internal pressure increase due to the generation of hydrogen gas during storage. The alkaline battery can be provided.

[Brief description of drawings]

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

[Explanation of reference numerals] 1 metal can 2 separator 4 gelled negative electrode 5 negative electrode current collector 6 insulating gasket

Claims (1)

Claim: What is claimed is: 1. An alkaline battery comprising a gelled negative electrode composed of a zinc alloy powder and an alkaline electrolyte, wherein the gelled negative electrode contains (a) an indium compound as an anticorrosive agent for the zinc alloy powder. From 0.01 to 1.0% by weight in terms of indium with respect to the zinc alloy powder, (b) an alkylbenzenesulfonic acid having an alkyl group having 35 or less carbon atoms, or a salt obtained by neutralizing the alkylbenzenesulfonic acid with an alkali metal. At least one selected from the group consisting of
An alkaline battery containing 1 to 1.0% by weight.