JPH02174066A - Manufacture of negative electrode active material for alkaline battery - Google Patents

Abstract

PURPOSE:To suppress the occurrence of hydrogen gas and improve corrosion resistance over a long period by electrolytically replacing bismuth, indium, mercury, or indium, bismuth, mercury in sequence on the surface of zinc-lead alloy powder then coating fluorinated alkyl ester. CONSTITUTION:Bismuth and indium or, on the contrary, indium and bismuth are electrolytically replaced in sequence on the surface of zinc-lead alloy powder, then mercury is electrolytically replaced, and fluorinated alkyl ester is coated, or bismuth is electrolytically replaced on the surface of zinc-lead alloy powder, then it is amalgamated with an indium-mercury alloy and coated with fluorinated alkyl ester. Their contents are lead 0.01-2.0wt.%, bismuth 0.05-0.2wt.%, indium 0.01-0.1wt.%, and mercury 0.01-1.0wt.%. The content of mercury is sharply decreased, the occurrence of hydrogen gas is suppressed over a long period, and corrosion resistance can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for producing a negative electrode active material for alkaline batteries.
In detail, bismuth, indium, and mercury are dispersed in a specific order on the surface of zinc-lead alloy powder and then coated with fluorinated alkyl ester. Hydrogen gas generation is suppressed for a long period of time, corrosion resistance is improved, and discharge performance is improved. The present invention relates to a method for producing a negative electrode active material that provides an alkaline battery with excellent properties.

[Prior Art] In an alkaline battery using zinc as a negative electrode active material, a strong alkaline electrolyte such as an aqueous potassium hydroxide solution is used, so the battery must be sealed tightly. This sealing of the battery is particularly important when attempting to miniaturize the battery, but it also traps hydrogen gas generated due to corrosion of zinc during battery storage. Therefore, during long-term storage, the gas pressure inside the battery increases, and the more tightly sealed the battery is, the greater the risk of explosion.

As a countermeasure, research has been conducted to prevent corrosion of zinc, which is an anode active material, and to reduce the generation of hydrogen gas inside the battery. is carried out exclusively. For this reason, the negative electrode active materials of alkaline batteries commercially available today contain about 1.5 weight factor of mercury, and as a social need, there is a strong expectation for the development of lower mercury or mercury-free batteries. It has started to be done.

Therefore, in order to reduce the mercury content in batteries, proposals have been made regarding frozen zinc alloy powders in which various metals are added to zinc. For example, bismuth, indium, and mercury, or zinc hydrate alloy powder in which indium, bismuth, and mercury are sequentially precipitated by substitution on the surface of zinc-lead alloy powder, or indium after bismuth is precipitated by substitution on the surface of zinc-lead alloy powder. - A frozen zinc alloy powder frozen with a mercury alloy has been proposed by the present inventors.

In addition, as a means to achieve the same objective, proposals have been made regarding negative electrode active materials to which surfactants are added. For example, the present inventors have proposed a negative electrode active material in which the surface of frozen zinc alloy powder, which is obtained by freezing zinc alloy powder obtained by adding lead, aluminum, indium, etc. to molten zinc, is coated with a fluorinated alkyl ester. has been done.

Such conventional zinc hydrate alloy powders or negative electrode active materials have both been effective in suppressing hydrogen gas generation to some extent.

[Problems to be Solved by the Invention] However, in the conventional frozen zinc alloy powder or negative electrode active material as proposed above, while reducing the mercury content to 1.0% by weight, Reduce to below,
It has not yet been possible to obtain an alkaline battery that achieves both a long-term reduction in the amount of hydrogen gas generated and an improvement in discharge performance at a high level in a well-balanced manner.

In view of the current situation, the present invention provides a method for producing a negative electrode active material for alkaline batteries, which significantly reduces the mercury content, suppresses hydrogen gas generation for a long period of time, improves corrosion resistance, and also improves discharge performance. The purpose is to provide

[Means for Solving the Problem] As a result of intensive research in line with this purpose, the present inventors have found that bismuth,
It has a three-layer structure in which indium, mercury, or indium, bismuth, and mercury are sequentially precipitated by substitution, or a two-layer structure in which bismuth is first precipitated by substitution on the surface of zinc-lead alloy powder and then iced with indium-mercury alloy. The present inventors have discovered that the above object can be achieved in a negative electrode active material in which the surface of a frozen zinc alloy powder is further coated with a fluorinated alkyl ester, and the present invention has been achieved.

That is, in the method for producing a negative electrode active material for alkaline batteries of the present invention, bismuth, indium, or conversely, indium and bismuth are sequentially precipitated by substitution on the surface of a zinc-lead alloy powder, and then mercury is precipitated by substitution, and then fluorinated alkyl It is characterized by coating the surface of the zinc-lead alloy powder with an ester, or by precipitating bismuth by substitution on the surface of the zinc-lead alloy powder, then freezing it with an indium-mercury alloy, and then coating it with a fluorinated alkyl ester.

Below, the manufacturing method of the present invention will be explained in more detail.

In the manufacturing method of the present invention, first, a zinc-lead alloy powder containing a predetermined amount of lead is obtained. One method is, for example, to add a predetermined amount of lead to molten zinc, stir it to form an alloy, then atomize it with compressed air, turn it into powder, and then sieve it to size it. .

Next, in the manufacturing method of the present invention, bismuth, indium, and mercury are added to the surface of the obtained zinc-lead alloy powder, and there are three methods for adding it.

(I): Bismuth, indium, and mercury are sequentially substituted and precipitated.

(■): Indium, bismuth, and mercury are sequentially substituted and precipitated.

(■); After bismuth is precipitated by substitution, it is iced with an indium-mercury alloy.

First, method (I) or (II) will be explained.

However, method (1) and method (II) differ only in the order in which bismuth and indium are precipitated by substitution.
Since the other aspects are common, only method (1) will be described as a method for substituting bismuth and indium to be precipitated.

That is, the zinc-lead alloy powder obtained above is poured into a dilute acidic solution, stirred and mixed, and the diluted acidic solution in which a predetermined amount of bismuth is dissolved is dropped therein. After the dropwise addition is completed, stirring is continued for about 1 hour to cause the bismuth in the dilute acidic solution to be displaced and precipitated on the surface of the zinc-lead alloy powder. The dilute acidic solution in which bismuth is dissolved used here can be suitably obtained by, for example, dissolving bismuth oxide in the dilute acidic solution. Furthermore, the dilute acidic solution used here is
Hydrochloric acid with a concentration of 5-15% is preferred.

Next, a dilute acidic solution in which a predetermined amount of indium was dissolved was added to the zinc-based solution in which the bismuth obtained above had been precipitated.
Dropped into a dilute acidic solution containing lead alloy powder while stirring,
Indium is substituted and precipitated on the surface of the powder in the same manner as in the case of bismuth.

The dilute acidic solution in which indium is dissolved used here can be suitably obtained by, for example, dissolving indium hydroxide in the dilute acidic solution. Further, as the dilute acidic solution, hydrochloric acid having a concentration of 5 to 15% is preferable, as in the case of displacement precipitation of bismuth.

Furthermore, in the method (1) or (II), mercury is precipitated by substitution on the surface of the zinc-lead alloy powder obtained above, in which bismuth, indium, or indium and bismuth are sequentially precipitated by substitution. is obtained.

In this method, a dilute acidic solution in which a predetermined amount of mercury is dissolved is dropped under stirring into a dilute acidic solution containing the above-mentioned bismuth, indium, or zinc-lead alloy powder in which indium and bismuth are sequentially precipitated. Then, mercury is precipitated by substitution on the surface of the powder in the same manner as bismuth and indium are precipitated by substitution. Next, the obtained powder is washed with water, filtered, and dried to obtain a frozen zinc alloy powder. The dilute acidic solution in which mercury is dissolved used here can be suitably obtained by, for example, dissolving mercuric chloride in the dilute acidic solution. In addition, as a dilute acidic solution, bismuth,
Hydrochloric acid having a concentration of 5 to 15% is preferred as in the case of displacement precipitation of indium.

The frozen zinc alloy powder obtained by the method (1) or (II) has a bismuth layer and an indium layer on the outer periphery of the zinc-lead alloy powder, or conversely an indium layer and a bismuth layer, and It has a mercury layer around its outer periphery.

On the other hand, in the method (■), the zinc-
First, bismuth is precipitated by substitution on the surface of lead alloy powder in the same manner as in method (1) or (n), and then iced with an indium-mercury alloy to obtain frozen zinc alloy powder. The method is carried out, for example, as follows.

That is, ``The above zinc-lead alloy powder in which bismuth has been precipitated by substitution and a predetermined amount of indium-mercury alloy are put into a dilute acidic solution or a dilute alkaline solution, and the mixture is mixed and stirred for about 1 hour while being subjected to a hydrogenation treatment. After washing with water, filtration and drying are performed to obtain a frozen zinc alloy powder.

The indium-mercury alloy used here is, for example, 10
% by mixing and alloying indium and mercury in hydrochloric acid. Further, as the dilute acidic solution, hydrochloric acid with a concentration of 5 to 15% is preferable, and as the dilute alkaline solution, a potassium hydroxide aqueous solution with a concentration of 5 to 15% is preferable.

The frozen zinc alloy powder obtained by the method (m) has a bismuth layer on the outer periphery of the zinc-lead alloy powder, and further has an indium-mercury alloy layer on the outer periphery.

Next, in the manufacturing method of the present invention, the above (1) to (m)
A negative electrode active material is obtained by coating the surface of the frozen zinc alloy powder obtained by the above method with a fluorinated alkyl ester. The following method is suitable as the method.

That is, the glazed zinc alloy powder obtained above is poured into a solvent such as toluene to which a predetermined amount of fluorinated alkyl ester has been added and stirred, and the metals present in the outer periphery of the glazed zinc alloy powder are removed. Impurities such as oxides are separated from the frozen zinc alloy powder, and the impurities are removed from the system. Thereafter, by drying and volatilizing the solvent, the surface of the frozen zinc alloy powder is coated with a fluorinated alkyl ester, thereby obtaining a negative electrode active material.

The fluorinated alkyl ester used in the production method of the present invention is a compound represented by the general formula %, where R and R' each represent a fluorinated alkyl group, and R and R' are the same or May be different. This fluorinated alkyl group has the general formula C,
F... Examples include those represented by + (n represents an integer of 1 or more). The number of carbon atoms (n
) is preferably in the range of 1 to 20, specifically R, R
' as trifluoromethyl group, pentafluoroethyl group, heptafluoropropyl group, nonafluorobutyl group, undecafluoropentyl group, tridecafluorohexyl group, pentadecafluoroheptyl group, heptadecafluorooctyl group, nonadecafluorobutyl group, fluorononyl group,
Heneicosafluorodecyl group, tricosafluoroundecyl group, pentacosafluorododecyl group, heptacosafluorotridecyl group, nonacosafluorotetradecyl group, hentriacontafluoropentadecyl group, tritriacontafluorohexadecyl group, Examples include fluorinated alkyl groups such as a pentatriacontafluoroheptadecyl group, a heptatriacontafluorooctadecyl group, a nonatriacontafluorononadecyl group, and a hetetracontafluoroeicosyl group. The fluorinated alkyl ester used in the production method of the present invention may be any one of the fluorinated alkyl esters represented by the above general formula, or may be a mixture of two or more. .

The coating amount of this fluorinated alkyl ester is 0.001 to 1.0 parts by weight based on 100 parts by weight of the frozen zinc alloy powder, and if it is less than o, ooi parts by weight, the corrosion resistance of zinc is improved and hydrogen If the effect of the present invention of suppressing gas generation is not sufficiently obtained, and if the amount exceeds 1.0 parts by weight, the coating layer of fluorinated alkyl ester formed on the surface of the frozen zinc alloy powder during discharge. The fluorinated alkyl ester present in the battery acts as a barrier and inhibits the zinc dissolution reaction, making it impossible to obtain good discharge performance.

The negative electrode active material obtained by the production method of the present invention contains 0.01 lead
~2.0% by weight, 0.05-0.2% by weight of bismuth,
0.01-0.1% by weight of indium, 0.01% of mercury
It contains ~1.0% by weight.

If the content of each of lead, bismuth, and indium is less than the above lower limit, the effect of addition on suppressing hydrogen gas generation and improving discharge performance when used as an alkaline battery is small. Moreover, when the upper limit was exceeded, the amount of hydrogen gas generated increased, corrosion resistance decreased, and discharge capacity also decreased.

On the other hand, when the negative electrode active material obtained by the production method of the present invention has an extremely low mercury content of 0.01-1.0% by weight, it has a higher content than the negative electrode active material obtained by other production methods. An alkaline battery in which hydrogen gas generation is significantly suppressed and discharge performance is improved can be obtained.

[Action] Although the action and effect of the present invention are not fully elucidated, the following may be considered.

(1) Bismuth and indium are both present on the surface of the zinc powder and have a sufficiently high hydrogen overvoltage, making it possible to replace the conventional effect of adding mercury. That is, even if the mercury content is reduced, corrosion resistance can be covered by adding these elements. Furthermore, lead is also an effective element for improving corrosion resistance.

(2) Since bismuth is difficult to amalgamate with mercury, the bismuth layer acts as a barrier to suppress the diffusion of mercury into the zinc alloy powder. Furthermore, since indium is amalgamated with mercury, indium suppresses the diffusion of mercury into the zinc alloy powder by amalgamating with mercury.

These actions maintain a high mercury concentration on the surface of the zinc alloy powder, so even a small amount of mercury can sufficiently exhibit the effects of mercury on improving corrosion resistance and battery characteristics.

(3) Because the fluorinated alkyl ester coated on the surface of the zinc chloride alloy powder acts as an inhibitor,
Effective in improving corrosion resistance.

(4) When coating the surface of a fluorinated zinc alloy powder with a fluorinated alkyl ester using a solvent such as toluene to which a fluorinated alkyl ester has been added, the fluorinated zinc alloy powder is stirred in the above solvent. Impurities that cause deterioration of battery performance, such as metal oxides present on the outer periphery of glazed zinc alloy powder, can be removed from the glazed zinc alloy powder by chelation, so that battery performance can be improved. Effective for improvement.

All of the above-mentioned effects of the present invention are such that each element of bismuth, indium, and mercury is produced by the production method of the present invention.
This is achieved by making a predetermined amount of lead alloy powder present in a specific order on the surface of the lead alloy powder, and further coating the surface with a predetermined amount of fluorinated alkyl ester.

The present invention provides a method for producing a negative electrode active material that is excellent in both corrosion resistance and discharge performance and is used as a negative electrode active material for alkaline batteries due to the synergistic effect of these respective actions.

[Examples] The present invention will be specifically described below based on Examples and Comparative Examples.

Examples 1 to 14 and Comparative Examples 1 to 7 Zinc ingots with a purity of 99.997% or more are melted at about 500°C, and lead is added to the melt to have the composition shown in Table 1 to form a zinc-lead alloy. It was created. Next, the obtained zinc-lead alloy is powdered using high-pressure argon gas (injection pressure 5'J/CIi'), and further sieved to reduce the particle size of the powder to 48.
The atomized powder shown in Table 1 was obtained by sizing to ~150 meshes.

Next, a frozen zinc alloy powder was obtained by the above manufacturing method (1).

That is, 200 g of the obtained atomized powder was put into a beaker containing 0.51 g of 10% hydrochloric acid, and stirred and mixed using a stirrer. On the other hand, 10% hydrochloric acid in which a predetermined amount of bismuth oxide was dissolved to have the composition shown in Table 1 was added to 0.0% hydrochloric acid. I prepared IJ. This bismuth-containing hydrochloric acid was dropped into the above-mentioned atomized powder-containing hydrochloric acid with stirring. After the dropwise addition was completed, stirring was continued for an additional hour to displace and precipitate the bismuth in the solution onto the surface of the atomized powder, thereby forming a bismuth layer around the outer periphery of the atomized powder.

Next, add 0.1% of 10% hydrochloric acid in which a predetermined amount of indium hydroxide was dissolved to have the composition shown in Table 1. This was dropped into hydrochloric acid containing the atomized powder having the bismuth layer with stirring. After the dropwise addition was completed, stirring was further continued for 1 hour, and the indium in the solution was displaced and precipitated on the surface of the powder, thereby forming an indium layer around the outer periphery of the powder.

Furthermore, prepare 0.1 f of 10% hydrochloric acid in which a predetermined amount of mercuric chloride is dissolved to have the composition shown in Table 1, and add this to the atomized powder containing the above-mentioned bismuth layer and indium layer sequentially. The mixture was added dropwise to hydrochloric acid with stirring. After the dropwise addition was completed, stirring was further continued for 1 hour to displace and precipitate the mercury in the solution onto the surface of the powder, thereby forming a mercury layer around the outer periphery of the powder. Subsequently, the obtained powder was washed with water, filtered, and dried to obtain glazed zinc alloy powder having the composition shown in Table 1.

Next, a predetermined amount of fluorinated alkyl ester (manufactured by Sumitomo 3M, trade name: Florado PC-430) having the composition shown in Table 1 was placed in a beaker, and toluene was added to the beaker at 0.0%. IJ was added and dissolved. The frozen zinc alloy powder obtained above was added to the toluene and stirred, and then the supernatant liquid of heated toluene containing metal oxides released from the frozen zinc alloy powder was removed. . Furthermore, the toluene was dried and volatilized while mixing the zinc chloride alloy powder put into toluene, and the surface of the fluorinated zinc alloy powder was coated with fluorinated alkyl ester to form a negative electrode active material having the composition shown in Table 1. Obtained. The numerical values of the fluorinated alkyl ester shown in Table 1 are the amounts (Ii measured parts) based on 100 parts by weight of the zinc chloride alloy powder.

A hydrogen gas generation test was conducted using each negative electrode active material thus obtained. The results are shown in Table 1.

In the hydrogen gas generation test, 5 days of an aqueous potassium hydroxide solution with a concentration of 40% by weight saturated with zinc oxide was used as the electrolytic solution. Gas generation rate (μQ/g-day) for 25 days and 60 days at 45°C using 10g of negative electrode active material
was measured.

Furthermore, electrolytes t and gg were prepared by adding about 1.0% of carboxymethylcellulose and sodium polyacrylate as gelling agents to a 40% potassium hydroxide aqueous solution saturated with zinc oxide, and The mixture was mixed with 3.0 g of the obtained negative electrode active material to form a gel, thereby obtaining a negative electrode material. On the other hand, a positive electrode material was obtained by mixing manganese dioxide and a conductive agent. Using these negative electrode materials and positive electrode materials, an alkaline manganese battery shown in FIG. 1 was prepared, and the battery performance was evaluated.

The alkaline manganese battery shown in Figure 1 consists of a positive electrode can 1, a positive electrode 2,
Negative electrode 3, separator 4, sealing body 5, negative electrode bottom plate 6, negative electrode current collector 7, cap 8, heat-shrinkable resin tube 9, insulation ring! 0.11, and consists of an outer can I2.

Using this alkaline manganese battery, the discharge load is 4Ω, 20Ω.
The discharge duration up to the final voltage of 0.9 V was measured under the discharge conditions of 1.5 °C, and it was found that the mercury content of the zinc alloy powder obtained by adding lead, aluminum, and indium to molten zinc was 1.5 V.
It is expressed as an index, with the measured value of Comparative Example 12 using a conventional frozen zinc alloy powder that has been subjected to a hydration treatment so as to have a concentration of 5% by weight as 100 as a negative electrode active material. The results are shown in Table 1.

Examples 15 to z8 Glyzed zinc having the composition shown in Table 1 in the same manner as Examples 1 to 14, respectively, according to the production method (n) above, that is, except that the order of replacing and precipitating bismuth and indium was reversed. An alloy powder was obtained.

Furthermore, Examples 1 to 3 were applied to the surface of the obtained zinc chloride alloy powder.
The negative electrode active materials having the compositions shown in Table 1 were obtained by coating them with fluorinated alkyl esters in the same manner as in No. 14.

Example 1 Using each negative electrode active material obtained in this way
A hydrogen gas generation test and a discharge test were conducted in the same manner as in 14 to 14, and the results are shown in Table 1.

Examples 29-42 A frozen zinc alloy powder was obtained according to the above manufacturing method (m).

That is, first, atomized powders having a bismuth layer were obtained in the same manner as in Examples 1 to 14, and the obtained powders were thoroughly washed with water. Next, an alloy of indium and mercury mixed in 10% hydrochloric acid and the atomized powder having the bismuth layer were poured into a 10% potassium hydroxide aqueous solution so as to have the composition shown in Table 1. The mixture was mixed and stirred for about 1 hour to carry out freezing treatment, and an indium-mercury alloy layer was formed around the outer periphery of the powder. Furthermore, the obtained powder was washed with water, filtered, and dried to obtain glazed zinc alloy powder having the composition shown in Table 1.

Next, Examples 1 to 1 were applied to the surface of the obtained zinc chloride alloy powder.
The negative electrode active materials having the compositions shown in Table 1 were obtained by coating with fluorinated alkyl esters in the same manner as in 4.

Example 1 Using each negative electrode active material obtained in this way
A hydrogen gas generation test and a discharge test were conducted in the same manner as in 14 to 14, and the results are shown in Table 1.

Comparative Examples 8 to 10 In Comparative Example 8, Example 2 was used, in Comparative Example 9, Example 16, and in Comparative Example IO, glazed zinc alloy powder obtained in the same manner as in Example 30 was used without coating with fluorinated alkyl ester. Using the material as a negative electrode active material, a hydrogen gas generation test and a discharge test were conducted in the same manner as in the examples, and the results are shown in Table 1.

Comparative Examples 11 to 14 Each element was added to molten zinc to have the composition shown in Table 1, and the atomized powder shown in Table 1 was obtained in the same manner as in Examples.

Subsequently, the obtained atomized powder was poured into a 10% potassium hydroxide aqueous solution, and metallic mercury was added dropwise under stirring to achieve the composition shown in Table 1 to perform an ice treatment, and after washing with water, filtration was performed. Drying was performed to obtain glazed zinc alloy powder having the composition shown in Table 1. In Comparative Examples 11 and 12, the obtained frozen zinc alloy powder was directly used as the negative electrode active material. Further, in Comparative Examples 13 and 14, the surface of the obtained frozen zinc alloy powder was coated with a fluorinated alkyl ester in the same manner as in Example 2 to obtain negative electrode active materials having the compositions shown in Table 1.

Using each negative electrode active material thus obtained, a hydrogen gas generation test and a discharge test were conducted in the same manner as in the examples, and the results are shown in Table 1.

As shown in Table 1, Examples 1 to 14 are negative electrode active materials obtained by coating the surface of the frozen zinc alloy powder obtained by the production method (1) with a fluorinated alkyl ester. Examples 15 to 28 are negative electrode active materials obtained by coating the surface of the frozen zinc alloy powder obtained by the production method (II) with a fluorinated alkyl ester, and Examples 29 to 42 are the negative electrode active materials obtained by coating the surface of the frozen zinc alloy powder obtained by the production method (II). ) is a negative electrode active material obtained by coating the surface of the frozen zinc alloy powder obtained with fluorinated alkyl ester, but both have a large hydrogen gas generation suppressing effect and excellent discharge performance.
In particular, the effect of suppressing hydrogen gas generation over a long period of time (60 days) was outstanding.

On the other hand, in Comparative Examples 1 to 7, the types and manufacturing methods of the added components are the same as those of Examples 1 to 14, and the content of the added components is within the composition range of the present invention. However, as mentioned above, the hydrogen gas generation suppressing effect and discharge performance were inferior.

Comparative Examples 8 to 1O are Example 2, Example 16, and Example 30.
The same frozen zinc alloy powder was used as the negative electrode active material without being coated with the fluorinated alkyl ester, but both the hydrogen gas generation suppressing effect and the discharge performance were poor.

In Comparative Examples 11-12, the negative electrode active material was a frozen zinc alloy powder having a different alloy composition from the frozen zinc alloy powder used in the present invention, but the mercury content was reduced to within the composition range of the present invention. In Comparative Example 11, at the same mercury content,
Both the hydrogen gas generation suppressing effect and the discharge performance were inferior. In addition, Comparative Example 12 where the mercury content was 1.5% by weight as in the conventional example.
Even though the mercury content was higher than that of the example, the effect of suppressing hydrogen gas generation over a long period of time (80 days) was inferior, and the discharge performance was also equal or lower.

Comparative Example 13 uses a conventional negative electrode active material in which the surface of the same frozen zinc alloy powder as Comparative Example 11 is coated with a fluorinated alkyl ester. The hydrogen gas generation suppressing effect and discharge performance over a period of 1 day) were poor.

Comparative Example 14 had the same composition as the negative electrode active material used in the present invention and was obtained by a manufacturing method different from that of the present invention, but was inferior in both hydrogen gas generation suppressing effect and discharge performance.

[Effects of the Invention] As explained above, the surface of the frozen zinc alloy powder obtained by the above manufacturing methods (1) to (m), in which lead, indium, bismuth, and mercury are dispersed in specific positions and within a certain composition range. The negative electrode active material obtained by the present invention, in which a certain amount of fluorinated alkyl ester is coated on
At an extremely low fraction of 1.0% by weight, it suppresses hydrogen gas generation over a long period of time, improves corrosion resistance, and improves discharge performance compared to various negative electrode active materials obtained by other manufacturing methods. can be done.

Therefore, the production method of the present invention is suitably used as a production method for negative electrode active materials used in alkaline batteries.

[Brief explanation of the drawing]

FIG. 1 shows a side sectional view of an alkaline manganese battery according to the present invention. 1... Positive electrode can, 2... Positive electrode, 3... Negative electrode, 4... Separator 5... Sealing body,
6... Negative electrode bottom plate, 7... Negative electrode current collector,
8... Cap, 9... Heat-shrinkable resin tube, 10111... Insulating ring, 12... Exterior can. Patent applicant Mitsui Metal Mining Co., Ltd.

Claims (1)

[Claims] 1. Bismuth, indium,
The method is characterized in that mercury is sequentially precipitated by substitution and then coated with a fluorinated alkyl ester.
0% by weight, bismuth 0.05-0.2% by weight, indium 0.01-0.1% by weight, mercury 0.01-1.
A method for producing a negative electrode active material for alkaline batteries containing 0% by weight. 2. Indium, bismuth,
The method is characterized in that mercury is sequentially precipitated by substitution and then coated with a fluorinated alkyl ester.
0% by weight, indium 0.01-0.1% by weight, bismuth 0.05-0.2% by weight, mercury 0.01-1.
A method for producing a negative electrode active material for alkaline batteries containing 0% by weight. 3. Bismuth is substituted and precipitated on the surface of zinc-lead alloy powder, then treated with an indium-mercury alloy, and further coated with a fluorinated alkyl ester. %, bismuth from 0.05 to 0.
2% by weight of indium, 0.01 to 0.1% by weight of indium, and 0.01 to 1.0% by weight of mercury.