JPH04138667A - Manufacture of zinc alkaline battery - Google Patents

Abstract

PURPOSE:To enhance leaktightness of a zinc alkaline battery by composing a gelled negative electrode of anticorrosive zinc alloy powder having specific elements combined together and a gelled alkaline electrolyte containing a predetermined amount of indium hydroxide powder to which a specific surfactant is added in a predetermined amount. CONSTITUTION:A zinc alloy having indium as its essential alloy component in which tin and bismuth are singly or combinedly contained, or anticorrosive zinc alloy powder having indium as its essential component in which tin and bismuth are singly or combinedly contained and in which also calcium and aluminium are singly or combinedly contained is fabricated. Powder of indium hydroxide is contained in the zinc alloy in the range 0.005 to 0.5wt.% of the alloy and a gelled alkaline electrolyte in which a polyethylene alkyl phenyl ether phosphoric surfactant expressed by the structural formula 1 or 2 is contained in the range 0.001 to 0.1wt.% of the zinc alloy is prepared. The zinc alloy powder is added to and mixed with the electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses zinc as a negative electrode active material, alkaline aqueous solution as an electrolyte, and manganese dioxide, silver oxide, or silver oxide as a positive electrode active material.
The present invention relates to mercury-free technology for zinc-alkaline batteries using oxygen, etc., and provides a method for producing zinc-alkaline batteries that are pollution-free and have excellent storage and discharge performance.

Conventional Technology Approximately ten years ago, there was a strong concern about environmental pollution caused by mercury in waste batteries, and research was conducted into reducing the amount of mercury in alkaline batteries. As a result, with the development of corrosion-resistant zinc alloys, etc., the amount of mercury contained in alkaline dry batteries is currently being reduced to 250 ppm relative to the battery weight. However, now that there is worldwide concern about environmental destruction caused by industrial products, as exemplified by the problem of ozone layer depletion caused by fluorocarbons, there is an increasing demand for the complete elimination of mercury in alkaline batteries.

A review of mercury-free alkaline batteries has been made since the time when mercury-containing alkaline batteries were being developed, and patents and Japanese literature have been published regarding various materials related to zinc alloys, inorganic inhibitors, and organic inhibitors.
Many applications and presentations have been made.

Indium is a material with a high hydrogen overvoltage and is known as an additive to the negative electrode of secondary batteries, regardless of the type of battery. Many applications and publications have also been made regarding methods of using metallic indium as an alloy additive element and methods of using indium compounds as inorganic inhibitors.

For example, the method of using it as an alloy additive element (Japanese Patent Publication No. 1-
41576), a method using indium oxide and indium hydroxide as inorganic inhibitors (Japanese Patent Publication No. 1973-
36450, JP-A-49-93831, JP-A-49-1
12125, 56th Electrical Engineering Conference Abstracts Collection 1 Presentation No. 8
GO5; page 205), method of adding indium oxide and cadmium oxide in combination (JP-A-1-105466)
). In addition, examples of adding it as an additive to the negative electrode of a secondary battery (JP-A-61-96666, JP-A-6L-1
01955) is also available.

In addition, organic inhibitors include jetanolamine,
Oleic acid, lauryl ether, amine, or ethylene oxide polymers have been proposed. Furthermore, as an example of the combined addition of an inorganic inhibitor and an organic inhibitor, it has been proposed to add indium hydroxide and an ethoxylfluoroalcohol polyfluoride compound in combination (JP-A-2-79367).

Invention or Problem to be Solved In a battery that uses pure zinc without mercury as the active material of the negative electrode,
The corrosion reaction of zinc accompanied by hydrogen generation occurs violently, increasing the internal pressure of the battery and pushing the electrolyte to the outside, resulting in a problem of reduced leakage resistance.

Additionally, in a partially discharged battery, the rate of hydrogen generation in the zinc negative electrode is accelerated, further reducing leakage resistance.

These results are due to the disappearance of mercury, which was suppressing corrosion reactions, by increasing the hydrogen overvoltage on the zinc surface.

Even with a corrosion-resistant zinc alloy containing indium, aluminum, and lead, which has been proven to have a corrosion-resistant effect by reducing mercury in the zinc negative electrode, if a battery is constructed without mercury, the leakage resistance of the battery after partial discharge cannot be ensured.

In addition, a battery constructed by adding commercially available indium oxide or indium hydroxide to a gel negative electrode using pure zinc powder as the negative electrode active material is as practical as a battery constructed only of the above-mentioned corrosion-resistant alloy. The leakage resistance of the battery cannot be ensured.

A battery can also be constructed by adding an amine-based surfactant, which is effective in reducing mercury, as an organic inhibitor to a gel negative electrode using a corrosion-resistant zinc alloy containing indium, aluminum, and lead as the active material of the negative electrode. , leakage resistance cannot be ensured.

Furthermore, even in a battery constructed by adding a combination of commercially available indium hydroxide and ethoxylfluoroalcohol-based polyfluoride compounds to a gel negative electrode that uses pure zinc powder as the negative electrode active material, the leakage resistance of the battery after partial discharge is low. Cannot be secured.

As described above, each of the conventional lenses does not have a complete corrosion inhibiting effect, and cannot be said to be practical at least for sealed batteries.

In order to make alkaline dry batteries mercury-free, the present inventors have developed materials that can exhibit the best combined effects of corrosion-resistant zinc alloys, inorganic inhibitors, and organic inhibitors, as well as their optimal conditions. The concentration was studied.

Means for Solving the Problems The gelled negative electrode of the battery of the present invention, which uses a combination of a corrosion-resistant zinc alloy, an inorganic inhibitor, and an organic inhibitor, contains indium, lead, bismuth, calcium, and aluminum in appropriate amounts in an appropriate combination. This gel is made by dispersing corrosion-resistant zinc alloy powder, which has been added with just 30%, and indium hydroxide powder, which has the appropriate properties as an inorganic inhibitor, at an appropriate concentration, and further added an appropriate amount of a surfactant with an appropriate structural formula as an organic inhibitor. It consists of an alkaline electrolyte. Furthermore, in order to make the corrosion-resistant zinc alloy, inorganic inhibitor, and organic inhibitor work effectively, it is effective to add indium hydroxide after the corrosion-resistant zinc alloy and surfactant are made to work together. Simultaneously acting on the corrosion-resistant zinc alloy with indium hydroxide and a surfactant is either ineffective or has an adverse effect.

The above surfactant is 0.001 to 0 for zinc alloy.
．． It is effective to include it in the alkaline electrolyte at 1 wt%.

In addition, the corrosion-resistant zinc alloy contains indium from 0.01 to 1 w.
t%, total of one or both of lead and bismuth is 0
．． Zinc alloy containing 0.005 to 0.5 wt%, or 0.01 to 1 wt% of indium, a total of 0.005 to 0.5 wt% of one or both of lead and bismuth, and one or two of calcium and aluminum. 0 in total
．． It is a zinc alloy containing 0.005 to 0.2 wt%. Further, an appropriate amount of indium hydroxide added is 0.005 to 0.5 wt% based on the zinc alloy.

Further, in view of the method of manufacturing a battery, it is desirable to use indium hydroxide synthesized by using indium chloride or indium sulfate as a starting material and neutralizing it in an aqueous solution. When using indium chloride as a starting material and using indium sulfate as a starting material, a product with better corrosion resistance can be obtained with the former. When indium nitrate and indium sulfate are used as starting materials, it is effective to use indium hydroxide synthesized by neutralization from an aqueous solution containing chlorine ions.

In addition, the above indium hydroxide has a particle size of 0.5 to 8
60 wt% or more of the total amount of particles in the μ range, preferably 7
A powder containing 0 wt% or more is effective.

Furthermore, it is effective that indium hydroxide has a thermal decomposition loss of 18 to 30% by weight up to 900°C, preferably 20 to 25%.

In addition, the surfactant has the structural formula below. %formula% W: Alkali metal or H n 4-20 m: 5-40 or W: Alkali metal or H n・　4〜20 m 5-40 It is effective if it is expressed as .

Function: The materials for the corrosion-resistant zinc alloy, inorganic inhibitor, and organic inhibitor of the present invention, as well as the combination and composition of their composites, were discovered as a result of intensive research to maximize the combined effects of each. Although the elucidation of its mechanism of action is currently unclear, it is inferred as follows.

First, the effects of each of the additive elements of the alloy, the inorganic inhibitor, and the organic inhibitor are as follows.

Among the additive elements in the alloy, indium, lead, and bismuth have the effect of increasing the hydrogen overvoltage of the elements themselves (and when added to zinc, they have the effect of increasing the hydrogen overvoltage on the surface of the element. In this case, since the additive element is present at the depth of the powder, this effect is maintained even if a new zinc surface appears due to the discharge.Also, aluminum and calcium have the effect of making the zinc particles spherical. In order to reduce the true specific surface area, the amount of corrosion per unit weight of zinc powder is reduced.

When indium hydroxide is dispersed as a powder in a gel-like alkaline electrolyte in coexistence with a zinc alloy, a portion of it is deposited on the surface of the zinc alloy by the principle of displacement plating, increasing the hydrogen overvoltage on the surface. The remaining part remains solid in the electrolyte, and when a new zinc alloy surface appears due to the discharge,
Electrodepositing on the new surface shows anti-corrosion effect.

When a surfactant coexists with a zinc alloy in a gel-like alkaline electrolyte, it chemically adsorbs onto the surface of the zinc alloy based on the principle of metal soap, forming a hydrophobic monomolecular layer, which exhibits an anticorrosion effect.

Next, the combined effect of zinc alloy and indium hydroxide will be explained. Since indium hydroxide acts by being electrodeposited on the surface of the zinc alloy, the electrodeposition must occur smoothly and uniformly. Since a significant amount of hydrogen gas is generated on the surface of the zinc alloy, which has no corrosion resistance, the electrodeposition of indium is hindered and the state of the electrodeposition becomes non-uniform. However, on the zinc alloy surface, which has good corrosion resistance, the generation of hydrogen gas is suppressed, and electrodeposition occurs smoothly and uniformly, resulting in a compound effect. This also applies to the state after partial discharge.

Next, the combined effect of the corrosion-resistant zinc alloy, indium hydroxide, and surfactant will be explained. The mechanism of action of indium hydroxide is as described above, but if all of the indium hydroxide is electrodeposited, there will be nothing left to act on after partial discharge. In addition to its own anti-corrosion effect, the surfactant is thought to have the effect of suppressing excessive indium electrodeposition and securing indium hydroxide that acts after partial discharge, when corrosion is more accelerated than when it is not discharged. In order to effectively perform this action, it is effective to add indium hydroxide after the corrosion-resistant zinc alloy and surfactant have been allowed to interact with each other. It is not effective to allow indium hydroxide and a surfactant to act on a corrosion-resistant zinc alloy at the same time.

Next, the meaning of limiting the properties of indium hydroxide will be explained. The finer the particle size, the better the dispersibility in the gel electrolyte, and the more uniform the effect can be exerted on the gel negative electrode. However, if it is too fine, it will dissolve all at once, making it impossible to secure enough amount to act after partial discharge. The limitation of weight loss during thermal decomposition is related to the crystallinity of indium hydroxide, which influences the solubility of its particles. If the thermal decomposition loss is too small, the solubility will be low, and if it is too large, the solubility will be too high.

Next, the meaning of limiting the method of synthesizing indium hydroxide will be explained. The properties of indium hydroxide vary depending on the synthesis method. Synthesis using indium chloride and indium sulfate as starting materials results in crystallinity and particle shape with excellent anticorrosion properties, as described above. When using indium chloride as a starting material and using indium sulfate as a starting material, the former produces a much better product. Furthermore, even in the case of synthesis using indium nitrate and indium sulfate as starting materials, if neutralization treatment is performed in an aqueous solution containing chloride ions, it is possible to synthesize indium hydroxide with the same properties as synthesis using indium chloride as a starting material. .

Next, the meaning of limiting the molecular structure of the surfactant will be explained. Surfactants with polyethylene oxide as their hydrophilic part have high solubility as micelles in alkaline electrolytes, and when added to electrolytes, they migrate to the zinc alloy surface,
It has a high corrosion prevention effect because adsorption occurs quickly. In addition, if the end of polyethylene oxide is a hydroxyl group, that is, an alcohol, it is easily hydrolyzed in an alkaline electrolyte.
The terminal group is preferably a phosphoric acid group. If you have an alkyl group in the lipophilic part,
When adsorbed onto the surface of a zinc alloy, it effectively eliminates electron exchange during corrosion reactions due to its high electrical insulation properties. If the bonding group between the hydrophilic part and the lipophilic part is a benzene ring, it exhibits alkali resistance or a strong and stable anticorrosion effect.

EXAMPLES The details and effects of the present invention will be explained below using examples.

First, in order to demonstrate the effects of the method for creating a corrosion-resistant zinc alloy, the method for synthesizing indium hydroxide, and the manufacturing method of the present invention, we will discuss the structure of the LR6 type alkaline manganese battery used in the examples and the method for comparative evaluation of leakage resistance. explain.

Corrosion-resistant zinc alloy powder is produced by melting 99.97% pure zinc, adding specified amounts of specified additive elements, and uniformly dissolving it.
It is made by the so-called atomization method, which is sprayed with compressed air and pulverized, and then classified with a sieve to obtain particles in the particle size range of 45 to 15.
Adjusted to 0 meshes.

Indium hydroxide was neutralized by adding a saturated amount of a specified indium salt to ion-exchanged water, and stirring the aqueous solution using a screw stirrer, adding ammonia gas as a neutralizing agent until the pH of the aqueous solution reached 9. After that, the pH of the filtrate was adjusted to 7 using ion-exchanged water on a filter with a mesh size of 0.5μ.
．． It was synthesized by washing with water until the temperature reached 5.5, separating water by pulling a vacuum from under the filter, and vacuum drying at 60°C.

The gelled negative electrode was prepared as follows. First, 3% by weight of sodium polyacrylate and 1% by weight of carboxymethyl cellulose are added to a 40% by weight potassium hydroxide solution (containing 3% by weight of ZnO) to form a gel. Next, while stirring this gel electrolyte, a predetermined amount of surfactant is added.
Stir and age for 2-3 hours. Next, a predetermined amount of indium hydroxide powder is gradually added and aged for 2 to 3 hours.

Furthermore, twice the weight ratio of zinc alloy powder was added to the gel electrolyte and mixed.

Figure 1 shows the alkaline manganese battery LR6 used in this example.
FIG. In FIG. 1, 1 is a positive electrode mixture;
2 is a gel negative electrode characterized by the present invention, 3 is a separator, and 4 is a current collector of the gel negative electrode. 5 is the positive terminal cap, 6 is the metal case, 7 is the battery exterior can, 8 is the case 6
A resin sealing body made of polyethylene closes the opening, and 9 is a bottom plate forming a negative electrode terminal.

The method for comparative evaluation of leakage resistance was to prototype 100 alkaline manganese batteries as shown in Figure 1 and partially discharge them to a depth of 20% of the theoretical capacity at a constant current of IA, which is the most severe condition for LR6. The number of batteries that leaked after storage at 60°C was evaluated as a leakage index (%). Under these severe conditions, if the leakage index is 0% after 30 days of storage at 60°C, it is desirable to be able to maintain reliability for practical use or leakage resistance for as long as possible.

Example 1 The present invention will be described in the case where a zinc alloy, an inorganic inhibitor, and an organic inhibitor are combined.

First, we investigated various additive elements and varied the composition of the zinc alloy. As a result, zinc alloys containing indium as an essential alloy component, and lead and bismuth, either singly or in combination, or indium as an essential component, lead and bismuth, either singly or in combination, and calcium. It was found that a zinc alloy system containing aluminum alone or in combination is good when used alone. Table 1 shows the best alloy composition group among them.

Table 1 Corrosion-resistant zinc alloy for mercury-free alkaline zinc batteries (in the table)
) indicates the amount of alloy components added> Table 2 shows batteries created by fixing the amount of surfactant added to 0.31 wt% and varying the amount of indium hydroxide added to the various zinc alloys shown in Table 1 above. The results of a leakage test after storage at 60°C for 60 days are shown.

As shown in Table 2, even zinc alloys with excellent corrosion resistance cannot ensure practical leakage resistance when used alone. However, it can be seen that leakage resistance can be ensured by adding appropriate amounts of surfactant and indium hydroxide. The amount of indium hydroxide added to each zinc alloy is preferably in the range of 0.005 to 0.5 wt%.

In the case of pure zinc, even if appropriate amounts of surfactant and indium hydroxide are added, practical leakage resistance cannot be ensured. Again, a combination with a suitable corrosion-resistant zinc alloy is required.

Table 3 shows the leakage after storage at 60°C for 60 days of batteries prepared by fixing the amount of indium hydroxide added to 0.1 wt% and varying the amount of surfactant added to the various zinc alloys shown in Table 1. Shows the liquid test results.

From Table 3, it can be seen that the amount of surfactant added to each zinc alloy is preferably in the range of 0.001 to 0.1 wt%. Here again, it can be seen that in the case of pure zinc, practical leakage resistance cannot be ensured even if appropriate amounts of surfactant and indium hydroxide are added.

Note that in this example, indium hydroxide synthesized by using sulfate as a starting material and neutralizing its aqueous solution was used, but the effect can also be obtained by using indium hydroxide using chloride or nitrate as a starting material. It will be done. The degree of effectiveness is determined by those using chloride as the starting material, those using sulfide as the starting material, and those using sulfide as the starting material.
The values were highest in the order of those using nitrate as the starting material.

In addition, the surfactant has the structural formula below. %formula% : A mixture of 11 was used.

Example 2 This invention is illustrated regarding the limitation of starting materials in the synthesis of indium hydroxide.

Table 4 shows the amount of surfactant added to each zinc alloy at 0.01.
The results of a leakage test after storage at 60'C for 75 days are shown for batteries with fixed wt% and 0.1 wt% of indium hydroxide, which is a different starting material.

Table 4 shows that nitrates synthesized in the presence of chloride ions are suitable. By the way, even for products using nitrate as the starting material, the leakage index is 0 at 60°C on the 60th day.
%, which is at a practical level, or batteries using chlorides and sulfates as starting materials have even longer-term leakage-proof reliability.

Example 3 An example of limiting the particle size range of indium hydroxide will be described.

Table 5 shows the leakage test results after 75 days at 60°C for batteries in which 1 wt % O was added to each zinc alloy with indium hydroxide having different particle size distributions.

From Table 5, particles with a particle size in the range of 0.5 to 8μ are 5 Q
wt% (The particles remaining on the filter with a coarseness of 0.5 μm during the water washing process of synthesis are used, so the remaining particles are 8 μm.
It is preferable to use indium hydroxide powder containing the above particles.At 70 wt% or more, liquid may not leak until 90 days at 60°C.

The indium hydroxides having different particle size distributions used in this example were obtained by using nitrate as a starting material, and classifying and adjusting the large particle size by a wet sedimentation method.

Example 4 An example of limiting the thermal decomposition loss of indium hydroxide will be described.

Table 6 shows the leakage test results after storage at 60° C. for 75 days for batteries in which 0.1 wt % of indium hydroxide with different thermal decomposition loss up to 900° C. was added to each zinc alloy.

From Table 6, the weight loss rate due to thermal decomposition is 18 to 30 wt%.
It is recommended to use indium hydroxide, and if it is 20 to 25%, it may not leak until 90 days at 60°C.

Indium hydroxides having different thermal decomposition weight loss values used in this example were prepared by using chloride as a starting material, neutralizing it, and changing the vacuum drying time after synthesis.

Example 5 Limitations on the composition of a corrosion-resistant zinc alloy will be explained. Table 7 shows that for each zinc alloy, the amount of organic inhibitor added is fixed at the optimum 0,601 wt%, the amount of indium hydroxide added is fixed at the optimum O, 1 wt%, and the additive elements of the alloy and their amounts are varied. 60℃60 of the battery made by
The results of the leakage test after storage for days are shown.

Table 7 Effect of alloy composition on the composite of zinc alloy, indium hydroxide and surfactant From this, the amount of indium added to the zinc alloy is 0.001 to 1 wt%, and the amount of lead and bismuth added individually or in total. 0.005-0.5wt%,
Alternatively, the total amount of calcium and aluminum, each alone or in combination, is 0.005 to 0.0. It can be seen that 2 wt% is appropriate.

The surfactant used in Example 5 was the same as in Example 1.

A surfactant having the following structural formula % W alkali metal or H n 4-20 m 5-40 or W alkali metal or H 4-20 5-40, or a mixture thereof with the same or higher Effects can be obtained.

Incidentally, in all of the examples, the effects of the present invention have been explained with reference to non-viscous zinc alloys, but the effects are sufficient even when the addition amount of mercury is extremely low, ranging from several PPM to several tens of PPM.

Effects of the Invention As described above, according to the present invention, in a zinc-alkaline battery, a zinc alloy having an appropriate composition in a gel-like alkaline electrolyte and a hydroxide having appropriate physical properties by an appropriate synthesis method are used. By adding indium, even without mercury, it is possible to suppress the increase in battery internal pressure due to corrosion of zinc and improve the leakage resistance of the battery more than expected.

By adding an appropriate amount of an organic inhibitor having an appropriate structural formula to this, a pollution-free zinc-alkaline battery with even better storage stability can be provided.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an alkaline manganese battery in an embodiment of the present invention. 1... Positive electrode mixture, 2... Gel-like negative electrode, 3... Separator.

Claims (7)

[Claims] (1) In preparing a gel-like negative electrode in which zinc alloy powder is mixed and dispersed in a gel-like alkaline electrolyte, a zinc alloy containing at least one member from the group of indium, lead, bismuth, calcium, and aluminum is used as an active material, The alkaline electrolyte contains an indium salt as a starting material and 0.005 to 0.5 wt% of indium hydroxide synthesized by neutralization in an aqueous solution based on the zinc alloy,
Furthermore, the following structural formula C_nH_2_n_+_1-C_6H_4-O-(CH
_2CH_2O)_m-PO_3W_2W: Alkali metal or H n: 4-20 m: 5-40 or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ W: Alkali metal or H n: 4-20 m: 5-40 A method for manufacturing a zinc-alkaline battery, characterized in that a polyethylene alkylphenyl ether phosphate surfactant or a mixture thereof is contained in an amount of 0.001 to 0.1 wt% based on the zinc alloy. (2) 0.01 to 1 wt% of indium and 0.005 to 0.5 wt of one or both of lead and bismuth in total
% of zinc alloy is used as a negative electrode active material. (3) 0.01 to 1 wt% of indium and 0.005 to 0.5 wt of one or both of lead and bismuth in total
%, and a zinc alloy containing a total of 0.005 to 0.2 wt % of calcium and one or two types of aluminum is used as the negative electrode active material. Law. (4) The method for producing a zinc-alkaline battery according to claim 1, wherein the indium salt is indium chloride or indium sulfate. (5) The method for manufacturing a zinc-alkaline battery according to claim 1, wherein the indium salt is indium nitrate or indium sulfate, and indium hydroxide synthesized by neutralization from an aqueous solution containing chlorine ions is used. (6) The synthesized indium hydroxide has a particle size of 0.
．． 2. The method for producing a zinc-alkaline battery according to claim 1, wherein the zinc-alkaline battery contains 60 wt% or more of the total amount of particles having a size of 5 to 8 μ. (7) The method for producing a zinc-alkaline battery according to claim 1, wherein the synthesized indium hydroxide has a weight loss rate of 18 to 30 wt% upon thermal decomposition up to 900°C.