JPH06223840A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To provide a zinc alkaline battery which generates no pollution and excels in the property of storing and also in the discharging performance. CONSTITUTION:In preparing a negative electrode of a zinc alkaline battery, no mercury, lead, cadmium, or indium is added, and the iron content is below 1ppm, and therein bismuth or a zinc alloy containing an appropriate amount of bismuth and calcium is used as the active material. As organic inhibitor, an appropriate amount of surface active agent is included in the alkaline electrolytic solution, wherein the agent has polyethylene oxide in the hydrophilic part and a fluoride alkyl radical in the lipophilic part, and further an appropriate amount of gallium hydroxide is included, and thereby a zinc alkaline battery which generates no pollution and excels in the property of storing and also the discharging performance is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a zinc-alkali battery using zinc as a negative electrode active material, an alkaline aqueous solution as an electrolytic solution, and manganese dioxide, silver oxide, oxygen, etc. as a positive electrode active material. The present invention provides a zinc-alkali battery that is pollution-free, has excellent storage properties, and has excellent discharge performance.

[0002]

2. Description of the Related Art Since about 10 years ago, there has been a strong concern about environmental pollution due to mercury in waste batteries, and studies have been made to reduce the amount of mercury in alkaline dry batteries. As a result, due to the development of corrosion-resistant zinc alloys and inhibitors, the amount of mercury contained in alkaline dry batteries was reduced to 250 ppm with respect to the battery weight, and further, anhydrous silver alkaline dry batteries were also released.

[0003] The approach to the technology of producing anhydrous silver for alkaline dry batteries has been made since the time when the alkaline dry batteries containing mercury were developed, and many applications and announcements have been made in patents and Japanese texts on various materials related to corrosion resistant zinc alloys and inhibitors. Has been done. For example, lead, indium, bismuth, calcium and the like are used as alloying elements for corrosion-resistant zinc alloys, and as inhibitors, such as indium hydroxide and certain surfactants. (Japanese Patent Laid-Open No. 4-26061)

[0004]

In a battery using pure zinc as an active material of a negative electrode as it is as anhydrous silver, a corrosive reaction accompanied by hydrogen generation of zinc occurs violently, and the internal pressure of the battery increases, so that the electrolytic solution is discharged to the outside. There is a problem of extrusion and deterioration of liquid leakage resistance. Further, in the partially discharged battery, the hydrogen generation rate of the zinc negative electrode is accelerated, and the leakage resistance is further reduced. These are due to the disappearance of the mercury that suppressed the corrosion reaction by increasing the hydrogen overvoltage on the zinc surface. As described above, lead, cadmium, indium, bismuth, calcium and the like are used as alloying addition elements of the corrosion-resistant zinc alloy in the technology of producing anhydrous silver for alkaline dry batteries. Especially, lead, cadmium, and indium are known as materials with high hydrogen overvoltage,
It exhibits an excellent effect in improving the corrosion resistance of zinc.

However, since lead and cadmium are pollutants similar to mercury, they can be said to be small amounts of additives for making the battery non-polluting, but they cannot be said to be desirable additive metals. Further, indium is generally not treated as a harmful substance and has a high anticorrosion property, so that it is known as an additive to the negative electrode of a secondary battery regardless of the primary battery. However, indium is not known for chronic poisoning either, and the American Industrial Hygienist Council (ACGIH) defines stricter permissible concentrations than lead.

However, in the corrosion-resistant zinc alloy containing bismuth or calcium without using lead, cadmium, or indium as well as mercury, it is not possible to secure the liquid leakage resistance of the battery after the partial discharge with a deep discharge depth, and the discharge performance is poor. However, there is a problem that the discharge performance is deteriorated especially at a low temperature.
Moreover, even if a battery is constructed by adding an organic inhibitor to a gel negative electrode that uses a corrosion-resistant zinc alloy containing bismuth and calcium as the negative electrode active material, the leakage resistance of the battery after partial discharge with a deep discharge depth is secured. As a result, the deterioration of the discharge performance at low temperature could not be resolved.

In the present invention, it is necessary to examine the materials capable of exerting the maximum effect and the optimum state and concentration of each of the corrosion-resistant zinc alloy and the organic inhibitor without using lead, cadmium, and indium as well as mercury. In view of the above, it is an object to provide an alkaline dry battery which suppresses corrosion of zinc, is pollution-free, and is excellent in storability and discharge performance.

[0008]

The zinc negative electrode portion of the present invention has an iron content of 1 ppm or less, and bismuth or
Using a zinc alloy containing bismuth and calcium as the active material, polyethylene oxide in the hydrophilic part, and a suitable amount of so-called perfluoroalkyl polyethylene oxide-based surfactant having a fluorinated alkyl group in the lipophilic part And an alkaline electrolyte containing gallium hydroxide in an appropriate amount.

In order to improve the resistance to liquid leakage, the zinc alloy has an iron content of 1 ppm or less and a bismuth and calcium content of 0.02 to 0.1 wt%.
It is necessary that the calcium content is 0 to 0.015 wt%.

The above-mentioned perfluoroalkyl polyethylene oxide type surfactant is
The anticorrosion effect can be exhibited by containing 0.0005 to 0.02 wt% in the alkaline electrolyte. .

Further, the gallium hydroxide is effective in improving the discharge performance by containing 0.005 to 0.1 wt% of the gallium hydroxide in the alkaline electrolyte.

[0012]

[Function] Regarding the material of the corrosion-resistant zinc alloy of the present invention, the inorganic type inhibitor, the organic type inhibitor, and the combination and composition in the combination thereof, those found as a result of earnest research so as to maximize the combination effect Is. The action is presumed as follows.

By reducing the content of impurities such as iron in zinc, generation of hydrogen gas due to corrosion of zinc can be suppressed, but iron, stainless steel, iron oxide, etc. are the only parts where gas is continuously generated. Since it is a place where a small amount of iron is mixed and unevenly distributed, the generation of hydrogen gas is suppressed by the synergistic effect of both by making the content of iron extremely small and by containing a certain amount of a specific additive element.

Among the additional elements in the alloy, bismuth has a high hydrogen overvoltage of the element itself, and is added to zinc to have an effect of increasing the hydrogen overvoltage of its surface. When this is uniformly added to the alloy, this effect is maintained even if a new zinc surface appears due to discharge, because the additive element exists at any depth of the powder. Further, calcium has the effect of making the zinc particles spherical, and reduces the true specific surface area, thus reducing the amount of corrosion of zinc per unit weight.

When the surfactant coexists with the zinc alloy in the gelled alkaline electrolyte, it chemically adsorbs on the surface of the zinc alloy by the principle of metallic soap to form a hydrophobic monomolecular layer and exhibits an anticorrosion effect. In particular, a surfactant having polyethylene oxide in the hydrophilic part has a high solubility as a micelle in an alkaline electrolyte, and when it is contained in the electrolyte, migration and adsorption to the zinc alloy surface occur rapidly, so anticorrosion Highly effective. Furthermore, if the lipophilic part has a fluorinated alkyl group, when it is adsorbed on the surface of the zinc alloy, it has a high electrical insulation property, which effectively hinders the electron transfer of the corrosion reaction, and also has a strong alkali resistance. Lasts.

The reason why the inclusion of gallium hydroxide contributes to the improvement of low-temperature discharge performance is not clear, but when coexisting with a zinc alloy in the gel alkaline electrolyte, gallium hydroxide is adsorbed on the surface of zinc and It is considered that it has the effect of suppressing the passivation in the zinc oxide film formed by the discharge reaction.

[0017]

The details and effects of the present invention will be described below with reference to examples. First, the method of making a corrosion resistant zinc alloy,
The structure of the LR6 type alkaline manganese battery used in the examples and the method for comparative evaluation of the gas generation rate and the liquid leakage resistance will be described in order to show the effects of the constitution of the present invention.

The corrosion resistant zinc alloy powder has an iron content of 1 p
Ionized zinc having a particle size of pm or less is melted at about 500 ° C., a predetermined amount of a predetermined additive element is added and uniformly dissolved, and then sprayed with compressed air to be powdered. The particles were classified with a sieve and adjusted to have a particle size range of 45 to 150 mesh. The iron content of the obtained zinc alloy powder is 1
It was below ppm.

The gelled zinc negative electrode was prepared as follows. First, a 40 wt% potassium hydroxide aqueous solution (ZnO
3% by weight) and 3% by weight of sodium polyacrylate and 1% by weight of carboxymethyl cellulose are added to gel. Then, a predetermined amount of a surfactant is added while stirring the gel electrolyte, and the mixture is stirred and aged for 2 to 3 hours. Next, the zinc alloy powder was added and mixed in a weight ratio twice that of the gel electrolyte.

FIG. 1 is a structural sectional view of an alkaline manganese battery LR6 used in this embodiment. In FIG. 1, 1 is a positive electrode mixture, 2 is a gelled negative electrode characterized by the present invention, 3 is a separator, and 4 is a gelled negative electrode current collector. 5 is a positive electrode terminal cap, 6 is a metal case, 7 is a battery outer can, 8
Is a resin sealing body that closes the opening of the case 6, and 9 is a bottom plate that serves as a negative electrode terminal.

Next, a method for comparative evaluation of gas generation rate and liquid leakage resistance will be described. The method for measuring the gas generation rate was 200% when the alkaline manganese battery shown in FIG. 1 was used, with a constant resistance of 1 Ω, which is the most severe condition for LR6, and a discharge time up to 0.9 V of 100%. After partial discharge up to 60 ° C., the amount of hydrogen gas generated by corrosion of the zinc alloy powder stored at 60 ° C. was measured and determined. 1
The discharge condition was set to 200% partial discharge under the condition of Ω for 128 minutes.

The method of comparative evaluation of liquid leakage resistance is as follows: 100 alkaline manganese batteries shown in FIG. 1 are partially discharged to 200% as in the case of measuring the gas generation rate.
It was stored at 60 ° C. for 60 days, and the number of leaked batteries was evaluated as a leak index (%).

The method of comparative evaluation of discharge performance was as follows. The alkaline manganese battery shown in FIG.
It was evaluated by the duration when discharged to 0.75 V with a constant resistance of Ω.

(Example 1) The iron content and the proper amount of the surfactant in the case where the zinc alloy powder in which the iron content is regulated and the surfactant as the organic inhibitor are compounded will be described.

Regarding the zinc alloy powder containing 0.05 wt% of bismuth in Table 1 and the zinc alloy powder containing 0.05 wt% of bismuth and 0.005 wt% of calcium, zinc having iron contents of 1 ppm or less and 5 ppm, respectively. Using an alloy powder, the content of gallium hydroxide was fixed to 0.05 wt% with respect to the zinc alloy powder, and no surfactant was added, and 0.0005 to 0.02 wt% with respect to the zinc alloy.
The hydrogen gas generation rate of the contained battery is shown. 60 ° C in Table 2
The leakage test result after storage for 60 days is shown.

[0026]

[Table 1]

[0027]

[Table 2]

The surfactant used as the organic inhibitor is the structural formula shown in Chemical formula 1.

[0029]

[Chemical 1]

The structural formula shown in Chemical formula 2 was used.

[0031]

[Chemical 2]

The same or higher effect can be obtained with the surface active agent. Of the above surfactants, the phosphoric acid type may be a mixture of primary and secondary phosphates.

From Table 1, in any of the zinc alloy powders, when the iron content was 5 ppm, the hydrogen gas generation rate was high, and no remarkable improvement was observed even if the surfactant was added. However, it can be seen that in the zinc alloy powder having an iron content of 1 ppm or less, the hydrogen gas generation rate is high when the surfactant is not added, but it can be reduced by adding an appropriate amount of the surfactant.

Similarly from Table 2, the iron content is 1 ppm.
It is understood that the leakage resistance up to 60 days at 60 ° C. can be significantly improved by using the following zinc alloy powder and adding an appropriate amount of a surfactant. The content of the surfactant is good in the range of 0.0005 to 0.02 wt% with respect to each zinc alloy powder.

The content of the surfactant is 0.02 wt.
%, Good results have been obtained with respect to liquid leakage resistance, but if 0.02 wt% is exceeded, a phenomenon occurs in which the closed circuit voltage immediately after heavy load discharge remarkably decreases. The range of 0.0005 to 0.02 wt% is preferable.

(Example 2) The proper alloy composition when a zinc alloy and a surfactant are compounded will be described.

In Tables 3 and 4, the content of gallium hydroxide was fixed to 0.05 wt% with respect to the zinc alloy powder, the content of surfactant was fixed to 0.005 wt%, and the zinc content of iron was 1 ppm or less. Regarding the alloy powder, the hydrogen gas generation rate of the battery created by changing the content of bismuth and calcium,
The results of a leakage test after storage at 60 ° C for 60 days are shown.

[0038]

[Table 3]

[0039]

[Table 4]

From Table 3, the content of bismuth is 0.02w.
If it is less than t%, the hydrogen gas generation rate is high, but 0.02 to
It is good in the range of 0.1 wt%. It is desirable that the content of calcium is small.

Similarly from Table 4, it can be seen that by containing appropriate amounts of bismuth and calcium, the leakage index is 0% up to 60 days at 60 ° C. and the leakage resistance can be secured. In addition,
Bismuth content is 0.02 to 0.1 wt% with respect to zinc
%, Calcium content is 0 to 0.015w with respect to zinc
Good in the range of t%.

The content of bismuth is 0.
Good results were obtained in the range of 1 wt% or more, but as shown in Table 3, the decrease in the hydrogen gas generation rate slowed down at 0.1 wt%, and even if the content was increased, further effects were recognized. If not, and if it exceeds 0.1 wt%, the phenomenon that the closed circuit voltage immediately after the heavy load discharge remarkably decreases occurs. Therefore, the content of bismuth is preferably in the range of 0.02 to 0.1 wt%.

(Example 3) The proper content of gallium hydroxide which is an inorganic inhibitor when a zinc alloy, a surfactant and gallium hydroxide are compounded will be described.

In Table 5, a zinc alloy powder having an iron content of 1 ppm or less and containing 0.05 wt% of bismuth and a zinc alloy powder containing 0.05 wt% of bismuth and 0.005 wt% of calcium were used. Content of 0.00
Fixed to 5 wt%, with no gallium hydroxide added,
The discharge performance of the battery containing 0.005 to 0.1 wt% with respect to the zinc alloy is shown. In addition, 0.05 wt% of bismuth
The discharge performance of the battery containing 0.05% by weight of gallium hydroxide was set to 100.

[0045]

[Table 5]

From Table 5, the content of gallium hydroxide is 0.
If it is less than 005 wt%, the discharge performance will be deteriorated. Also, 0.
In the range of 1 wt% or more, no further effect is observed even if the content is further increased, and the content of gallium hydroxide is preferably in the range of 0.005 to 0.1 wt%.

[0047]

As described above, according to the present invention, in a zinc alkaline battery, in an alkaline electrolyte, a zinc alloy having a proper composition in which the content of iron is regulated and an organic compound having a proper structural formula are used. The compound effect more than expected can be obtained by containing an appropriate amount of surfactant as a system inhibitor and an appropriate amount of gallium hydroxide, and the internal pressure of the battery due to corrosion of zinc without using mercury, lead, cadmium, or indium. It is possible to provide a non-polluting zinc-alkaline battery having excellent storage properties and discharge performance, which can suppress the rise in the battery and improve the liquid leakage resistance of the battery.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Positive Electrode Mixture 2 Gel Negative Electrode 3 Separator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Miura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (4)

[Claims] 1. Mercury, lead, cadmium and indium are not added, iron content is 1 ppm or less, and bismuth or a zinc alloy containing bismuth and calcium is used as an active material in an alkaline electrolyte. A zinc-alkaline battery characterized by containing a surfactant having polyethylene oxide in a hydrophilic part and a fluoroalkyl group in a lipophilic part, and further containing gallium hydroxide. 2. The zinc alkaline battery according to claim 1, wherein a zinc alloy containing 0.02 to 0.1 wt% of bismuth and 0 to 0.015 wt% of calcium is used as a negative electrode active material. 3. The surface active agent for zinc alloy is less than 0.1%.
The zinc alkaline battery according to claim 1, wherein the zinc alkaline battery is contained in an amount of 0005 to 0.02 wt%. 4. The zinc alkaline battery according to claim 1, wherein the gallium hydroxide is contained in 0.005 to 0.1 wt% with respect to the zinc alloy.