JPH0286063A - Alkaline battery and negative electrode active material thereof - Google Patents

Abstract

PURPOSE:To reduce the content of mercury by using a negative electrode material added with a specific quantity of polyoxyethylene alkyl ether sulfate triethanol ammonium salt to zinc alloy powder. CONSTITUTION:A negative electrode material containing zinc alloy powder and an electrolyte and added with polyoxyethylene alkyl ether sulfate triethanol ammonium salt 0.001-1.0 pts.wt. to zinc alloy powder 100 pts.wt. is used in this alkaline battery. Polyoxyethylene alkyl ether sulfate triethanol ammonium salt is adsorbed on the surface of alloy powder and serves as an inhibitor during the storage of the battery, thus the corrosion resistance of zinc is improved, and the occurrence of hydrogen gas is suppressed. The hindrance of electric contact between alloy powder due to hydrogen gas bubbles is suppressed at the time of a discharge, and the discharge performance is improved. The occurrence of hydrogen gas is suppressed even if the mercury content of zinc alloy powder is extremely small, and the battery performance can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an alkaline battery and its negative electrode active material, and more specifically, the present invention relates to an alkaline battery and its negative electrode active material. S
o HN(CH2CH20H) 32 4 n
3 [In the formula, R represents an alkyl group, and n represents an integer of 0 or more] Polyoxyethylene alkyl ether sulfate triethanol ammonium salt represented by Q, QQl~ with respect to 100 parts by weight of the zinc alloy powder It relates to an alkaline battery and its negative electrode active material in which the amount of hydrogen gas generated is significantly suppressed and the battery performance is improved by adding 1.0 part by weight.

[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 completely the battery is sealed, the greater the risk of explosion.

As a countermeasure, research has been conducted to prevent corrosion of zinc, which is an active material for the negative electrode, and to reduce the generation of hydrogen gas inside the battery. It is being done. For this reason, the negative electrode active materials of alkaline batteries commercially available today contain a large amount of mercury, about 3.0% by weight, and there is a social need to develop lower mercury or mercury-free batteries. It has become highly anticipated.

Therefore, various proposals have been made regarding zinc alloy powders in which various metals are added to zinc in order to reduce the mercury content in batteries. For example, there are zinc alloy powders in which lead is added to zinc, or zinc alloy powders in which lead and indium are added to zinc (Japanese Patent Application Laid-Open No. 181268/1983). Further, zinc alloy powders to which gallium, aluminum, etc. are added have also been proposed.

[Problems to be Solved by the Invention] By using zinc alloy powder in this way, it is certainly possible to suppress hydrogen gas generation even if the mercury content is reduced to a certain extent. The problem of deterioration in discharge performance accompanying a significant reduction in In other words, if the mercury content of zinc alloy powder is reduced to about 0.1 to 0.2% by weight in response to social needs, compared to the conventional mercury content of about 3.0% by weight. The hydrogen gas generation rate increases by about 4 to 5 times, and the discharge performance deteriorates to about 80%.

The following may be the cause of this.

That is, the following is considered to be the effect of mercury in the battery.

(1) Helps electrical contact between zinc alloy powder particles.

(2) It is effective in suppressing the formation of a passivation film on the surface of zinc alloy powder particles and uniformly dissolving zinc.

(3) Improve the corrosion resistance of zinc, and suppress electrical contact between zinc alloy powder particles from being inhibited by hydrogen gas bubbles generated as zinc corrodes.

However, when the mercury content of the zinc alloy powder becomes an ultra-low mercury content of 0.2% by weight or less, the effect of mercury in item (3) is no longer fully exerted, resulting in deterioration of discharge performance. It is thought that then.

In view of the current situation, it is an object of the present invention to provide an alkaline battery and its negative electrode active material in which the mercury content is significantly reduced, hydrogen gas generation is suppressed, and discharge performance is maintained at a high level. .

[Means for Solving the Problems] As a result of intensive research in line with this objective, the present inventors have found that polyoxyethylene alkyl ether sulfate triethanol is added to a negative electrode active material made of zinc alloy powder or an electrolyte made of an alkaline aqueous solution. By adding a specific amount of ammonium salt, it is possible to obtain an alkaline battery with significantly suppressed hydrogen gas generation and improved discharge performance compared to a battery without the addition of polyoxyethylene alkyl ether sulfate triethanol ammonium salt. Heading The present invention has been arrived at.

That is, the alkaline battery of the present invention includes a zinc alloy powder and an electrolyte, and contains 0.00 parts by weight per 100 parts by weight of the zinc alloy powder.
The alkaline battery has a negative electrode material to which polyoxyethylene alkyl ether sulfate triethanol ammonium salt is added in an amount of 0.001 to 1.0 parts by weight.

The present invention will be explained in more detail below.

In the present invention, the zinc alloy powder used as the negative electrode active material contains a certain amount of at least one of lead, aluminum, indium, magnesium, calcium, cadmium, tin, gallium, nickel, silver, etc. is exemplified. The method for producing this zinc alloy powder includes, for example, adding a predetermined amount of additional elements such as lead and aluminum to molten zinc, stirring to form an alloy, and then atomizing with compressed air to form a powder. The powder obtained by further sieving and sizing is used. The content of each additional element in this zinc alloy powder is 0
．． 0.001 to 0.5% by weight is common.

In the present invention, powdered zinc alloy powder obtained by further adding a desired amount of mercury during the production of the zinc alloy powder,
The above-mentioned zinc alloy powder is dry-blended with a desired amount of mercury using a V-type mill or a rotating drum, or the above-mentioned zinc alloy powder is mixed with a diluted solution such as potassium hydroxide or sodium hydroxide. A frozen zinc alloy powder obtained by wet oxidation with a desired amount of mercury in an alkaline solution may be used, in which case the mercury content in the frozen zinc alloy powder is lower than conventionally, i.e. 3.0 wt. % or less, and in consideration of low pollution, it is more preferably 1.5% by weight or less.

Further, the polyoxyethylene alkyl ether sulfate triethanol ammonium salt used in the present invention is a compound represented by the general formula %), where R is the general formula CH (m represents an integer of 1 or more). represents an alkyl group represented by 1I211+, where n represents an integer of 0 or more.

The preferable range of the carbon number (■) of the group represented by R here is 1 to 20, and specifically preferable R includes a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group,
Examples of alkyl groups include hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, eicosyl group, etc. It will be done. In addition, in the present invention, R is of the general formula CH (, represents an integer of 1 or more) ta
Also usable are those in which R is a cis-9-octadecenyl group (oleyl group), which exhibits the same effect as the alkyl group represented by 2m+1. The polyoxyethylene alkyl ether sulfate triethanol ammonium salt used in the present invention may be any one of the polyoxyethylene alkyl ether sulfate triethanol ammonium salts represented by the above general formula, or two. It may be a mixture of more than one species.

In the alkaline battery of the present invention, in the negative electrode material containing the zinc alloy powder and an electrolyte such as an aqueous potassium hydroxide solution,
Add the polyoxyethylene alkyl ether sulfate triethanol ammonium salt described above. The addition method is to coat polyoxyethylene alkyl ether sulfate triethanol ammonium salt on zinc alloy powder and use it as a negative electrode active material, or to add it to an electrolytic solution such as potassium hydroxide aqueous solution or sodium hydroxide aqueous solution or gel. For example, a method of adding the zinc alloy powder to a curing agent is exemplified, but in the present invention, the zinc alloy powder is mixed in a solvent such as toluene to which polyoxyethylene alkyl ether sulfate triethanol ammonium salt is added, and then the solvent is added. Forming a coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt on the surface of the zinc alloy powder by drying and volatilizing it and using this as a negative electrode active material has the effect of suppressing hydrogen gas generation and improving discharge performance. most preferred.

In the present invention, the zinc alloy powder on which the coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt is formed is processed by the same method as the method for forming the zinc alloy powder described above. The zinc alloy powder may be used by freezing to form a coating layer containing a mixture of polyoxyethylene alkyl ether sulfate triethanol ammonium salt and mercury on the surface of the zinc alloy powder. Further, mercury may be added and mixed into the electrolytic solution forming the negative electrode material together with the zinc alloy powder on which the coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt is formed.

Here, the amount of polyoxyethylene alkyl ether sulfate triethanol ammonium salt added to the negative electrode material is the same as the above zinc alloy powder lo.

It is 0.001 -t, o parts by weight. If the amount of polyoxyethylene alkyl ether sulfate triethanol ammonium salt added is less than 0.001 part by weight, the effect of the present invention, which improves the corrosion resistance of zinc and prevents hydrogen gas generation, cannot be obtained. If it exceeds the limit, during discharge, the polyoxyethylene alkyl ether sulfate triethanol ammonium salt present in the coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt formed on the surface of the zinc alloy powder, the electrolyte, etc. becomes a barrier. As a result, the dissolution reaction of zinc is inhibited, and good discharge performance cannot be obtained.

Although the effects of these polyoxyethylene alkyl ether sulfate triethanol ammonium salts have not been fully elucidated, it is presumed that polyoxyethylene alkyl ether sulfate triethanol ammonium salts are adsorbed on the surface of the zinc alloy powder during battery storage. This is effective in improving the corrosion resistance of zinc as it acts as an inhibitor, suppressing the generation of hydrogen gas that accompanies corrosion of zinc, and furthermore, preventing hydrogen gas from forming between particles of zinc alloy powder due to hydrogen gas bubbles that were previously seen during discharge. It is thought that discharge performance is improved by suppressing adverse effects such as inhibition of electrical contact.

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

Examples 1 to 5 and Comparative Examples 1 to 3 Zinc alloys were created by melting zinc ingots with a purity of 99.997% or higher at about 500°C and adding each element shown in Table 1 except for mercury. This is then heated with high pressure argon gas (ejection pressure 5
Kg/m). This powder is 50 to 15
Zinc alloy powder was obtained by sieving to a particle size range of 0 mesh.

Next, mercury was added to the above powder in an alkaline solution of 10% potassium hydroxide so that the content ratio shown in Table 1 was obtained, and a freezing treatment was performed to obtain the frozen zinc alloy powder shown in Table 1. Obtained.

Next, polyoxyethylene alkyl ether sulfate triethanol ammonium salt [manufactured by NOF ■, product name: Barsoft EFT] was added, and the above frozen zinc alloy powder was poured into the toluene solvent and mixed. While drying and volatilizing the toluene, a coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt in the proportions shown in Table 1 was formed on the surface of the frozen zinc alloy powder, thereby forming a negative electrode active material.

Further, an electrolytic solution was prepared by adding about 1.0% of carboxymethyl cellulose and sodium polyacrylate as gelling agents to a 40% potassium hydroxide aqueous solution saturated with zinc oxide.

3.0 g of negative electrode active material obtained above and 1.8 g of electrolyte
A negative electrode material was prepared by mixing g and forming a gel. Also,
A positive electrode material was prepared 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 tested.

The alkaline manganese battery shown in Figure 1 consists of a positive electrode can 1, a positive electrode 2,
Negative electrode (gelled frozen zinc alloy powder) 3, separator 4, sealing body 5, negative electrode bottom plate 6, negative electrode current collector 7, cap 8, heat-shrinkable resin tube 9, insulating ring to, tt
, and an exterior can 12.

Using this alkaline manganese battery, the discharge load is 2Ω, 20
The discharge duration up to the final voltage of 0.9 V was determined by n1 according to the discharge conditions of °C, and the measured value of Comparative Example 1 using a conventional negative electrode material not containing polyoxyethylene alkyl ether sulfate triethanol ammonium salt was set as 100. Shown as an index. The results are shown in Table 1.

In addition, we determined the gas generation rate (!!t1/g-day) for 20 days at 60°C using the above negative electrode material, and compared the results with conventional negative electrodes that do not contain polyoxyethylene alkyl ether sulfate triethanol ammonium salt. The values are also listed in Table 1 as an index with the measured value of Comparative Example 1 using the material as 1.0.

Example 6 Polyoxyethylene alkyl ether sulfate triethanol ammonium salt [NOF] was applied to the surface of an unfrozen zinc alloy powder similar to that in Example 2 in the same manner as in Example 2 without being subjected to ice treatment. After forming a coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt in the proportions shown in Table 1 using a
The discharge duration was determined in the same manner as in Example 2, except that the same method as in Example 2 was used as the negative electrode active material, which was obtained by carrying out the oxidation treatment so that the proportions shown in Table 1 were obtained. and gas generation rate, and compare each result to the first
Also listed in the table.

Example 7 Polyoxyethylene alkyl ether sulfate triethanol ammonium salt [NOF■ 3.0 g of a negative electrode active material obtained by forming a coating layer of polyoxyethylene alkyl ether sulfate triethanol ammonium salt in the proportions shown in Table 1 using Bar Soft EPT, manufactured by MHPS Co., Ltd., and 3.0 g of mercury. 0 mg, Example 2
The discharge duration and gas generation rate were measured in the same manner as in Example 2, except that the negative electrode material was made by adding and mixing 1.8 g of the same electrolytic solution to form a gel. It is also listed in Table 1.

Example 8 1.8 g of the same electrolyte as in Example 2 was mixed with 3.0 g of the same frozen zinc alloy powder as in Example 2 and polyoxyethylene alkyl ether sulfate triethanol ammonium salt [manufactured by NOF ■]. , trade name: Bar Soft EFT] 33.0m was added and mixed to form a gel, and the negative electrode material was used.The discharge duration and gas generation rate were measured in the same manner as in Example 2, respectively. The results are also listed in Table 1.

As shown in Table 1, a negative electrode material is used in which the negative electrode active material is a glazed zinc alloy powder coated with polyoxyethylene alkyl ether sulfate triethanol ammonium salt having a mercury content of 0.1% by weight. Compared to Comparative Examples 1 to 2 in which polyoxyethylene alkyl ether sulfate triethanol ammonium salt was not added to the negative electrode material, Examples 1 to 4 were different in composition of the zinc chloride alloy powder that was the negative electrode active material. Nevertheless, the hydrogen gas generation rate was significantly reduced, and the alkaline battery incorporating this negative electrode material had excellent discharge performance.

In addition, Example 5 uses a negative electrode material in which the negative electrode active material is a frozen zinc alloy powder with a mercury content of 1.0% by weight coated with polyoxyethylene alkyl ether sulfate triethanol ammonium salt. However, in this case as well, compared to Comparative Example 3 in which polyoxyethylene alkyl ether sulfate triethanol ammonium salt was not added to the negative electrode material, the discharge performance of the alkaline battery incorporating this negative electrode material was improved, and hydrogen gas The incidence was significantly reduced.

Furthermore, Example 6 uses a negative electrode material in which the surface of a futurized zinc alloy powder is coated with polyoxyethylene alkyl ether sulfate triethanol ammonium salt and then subjected to ice treatment as a negative electrode active material. but,
In this case as well, the hydrogen gas generation rate was significantly reduced, and the alkaline battery incorporating this negative electrode material had excellent discharge performance.

In Example 7, polyoxyethylene alkyl ether sulfate triethanol ammonium salt was coated on the surface of uncured zinc alloy powder as a negative electrode active material, and the negative electrode material obtained by adding and mixing together with mercury into an electrolyte solution was used. Even in this case, the hydrogen gas generation rate was significantly reduced and the discharge performance of the alkaline battery incorporating this negative electrode material was significantly improved.

Example 8 uses a negative electrode material in which a predetermined amount of polyoxyethylene alkyl ether sulfate triethanol ammonium salt is added and mixed into an alkaline aqueous solution as an electrolyte. It was effective, and it was also effective in improving the discharge performance of alkaline batteries incorporating this negative electrode material.

[Effects of the Invention] As explained above, according to the alkaline battery of the present invention having a negative electrode material to which a specific amount of polyoxyethylene alkyl ether sulfate triethanol ammonium salt is added, when the mercury content ratio is lowered than before In particular, even when the mercury content is extremely low, such as 0.2% by weight or less of the zinc alloy powder used, hydrogen gas generation within the battery is significantly suppressed, and the battery performance is improved. Furthermore, since the mercury content can be lowered than before, it also meets social needs. especially,
The effect is even more remarkable by using a negative electrode active material in which zinc alloy powder is coated with a specific amount of polyoxyethylene alkyl ether sulfate triethanol ammonium salt.

[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, 10,
11: Insulation ring, 12: Exterior can. Patent applicant Mitsui Metal Mining Co., Ltd.

Claims (1)

[Claims] 1. Zinc alloy powder and electrolyte, the zinc alloy powder 10
An alkaline battery having a negative electrode material to which 0.001 to 1.0 parts by weight of polyoxyethylene alkyl ether sulfate triethanol ammonium salt is added. 2. 0.001 to 1 per 100 parts by weight of zinc alloy powder
．． A negative electrode active material for an alkaline battery comprising 0 parts by weight of polyoxyethylene alkyl ether sulfate triethanol ammonium salt coated on the surface of the zinc alloy powder.