JPH0620688A - Zinc alkaline battery - Google Patents

Abstract

PURPOSE:To prevent reduction in corrosion resistance and discharge performance as battery even in case of non-amalgamation by adding In to a zinc alloy powder surface containing Sn and one or more selected from Bi, Al and Ca to cover the surface, and using the resulting powder as a negative electrode active material. CONSTITUTION:Zinc metal having a purity of 99.995wt.% (hereinafter simply referred to as %) is fused at about 50 deg.C, 0.005-0.05% of Sn, the same % of Bi, 0.01-0.005% of Al, and the same % of Ca are added thereto, and the fusion is pulverized by atomization and sieved to form a zinc alloy powder having a determined particle size. To this zinc allow power, 0.05-0.80% of In is added, a mixer is internally laid in nitrogen atmosphere and heated to 180 deg.C to mix them for 1hr. Thus, a coated zinc alloy powder in which In is fused to the particle surface is provided. This is used as a negative electrode active material, whereby a zinc alkaline battery which never reduce corrosion resistance nor discharge performance as battery even when not amalgamated can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc-alkaline battery using a zinc alloy powder as a negative electrode active material, an alkaline electrolyte as an electrolytic solution, and manganese dioxide, silver oxide, oxygen, nickel hydroxide or the like as a positive electrode active material.

[0002]

2. Description of the Related Art Conventionally, a common problem in this type of zinc-alkaline battery is corrosion of a negative electrode active material during storage by an electrolytic solution. As a countermeasure, as industrial means, zinc hydride powder added with about 5 to 10% by weight of mercury is used as a negative electrode active material, the hydrogen overvoltage of the negative electrode active material is increased, and corrosion of the negative electrode active material by an electrolytic solution is practically used. It has been suppressed to such an extent that there is no problem.

However, in recent years, in order to reduce pollution, reduction of mercury contained in a battery has increased as a social need, and various researches have been made. For example, zinc containing lead or aluminum in zinc. Zinc hydride alloy powder (Japanese Patent Publication No. 1-42114) in which the alloy is selectively reduced by an indium-mercury alloy and the content of mercury is reduced to about 0.6% by weight has come to be used as a negative electrode active material. . Further, technical improvements have been made, and zinc alloy powder having a mercury content of about 0.15 wt% is used as a negative electrode active material.

[0004]

However, in recent years,
Environmental pollution due to mercury has become a problem, and development of batteries containing no mercury has been strongly expected. In the above conventional technique, the conversion ratio is 0.6% by weight, and further 0.15%.
Despite the extremely low concentration of wt%, the negative electrode active material still contains mercury, and it cannot be said that the environmental problems have been solved. Further, if considering the resource problem in addition to the environmental problem, it is desirable to regenerate zinc or the like from a used battery, but if mercury is associated with zinc, countermeasures against mercury in the regeneration process become a problem.

The present invention is intended to solve such a problem, and is a zinc-alkaline battery using a zinc alloy powder as a negative electrode active material, which does not deteriorate corrosion resistance and discharge performance as a battery even if it is made smooth. It is intended to provide.

[0006]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors for this purpose, a zinc alloy powder containing tin and further containing at least one selected from bismuth, aluminum and calcium was obtained. By using a coated zinc alloy powder obtained by coating the surface with indium added as a negative electrode active material, it has been found that it is possible to provide a zinc-alkali battery that is free of problems and has no problem in corrosion resistance and discharge performance as a battery. completed.

The indium content in the coated zinc alloy powder is preferably 0.05 to 0.80% by weight. This is because when the indium content ratio is within this range, the gas generation amount due to corrosion can be suppressed within the allowable range, but when the indium content ratio is outside this range, the gas generation amount due to corrosion exceeds the allowable range.

The tin content in the coated zinc alloy powder is preferably 0.005 to 0.05% by weight, and the bismuth content in the coated zinc alloy powder is 0.005 to 0.05% by weight.
Is preferred. This is because when the content ratios of tin and bismuth are within these ranges, the gas generation amount due to corrosion can be suppressed within the allowable range, but when the content ratios deviate from these ranges, the gas generation amount due to corrosion exceeds the allowable range.

The content of aluminum in the coated zinc alloy powder is preferably 0.01 to 0.05% by weight, and the content of calcium in the coated zinc alloy powder is 0.01 to 0.05.
Weight percent is preferred. When the content ratio of aluminum and calcium is within these ranges, the gas generation amount due to corrosion is suppressed within the allowable range, but when the content ratios of aluminum and calcium are outside these ranges, the gas generation amount due to corrosion is within the allowable range. Because it will exceed.

[0010]

First, considering the effect of the coating of indium, coating the surface of the zinc alloy powder with indium increases the hydrogen overvoltage of the negative electrode active material and suppresses gas generation due to corrosion. It is considered that the contact between the particles of the alloy powder is improved and the discharge performance of the battery is improved. Considering the alloying effect of tin and bismuth, it is considered that alloying tin and bismuth with zinc alloy powder increases the hydrogen overvoltage of the negative electrode active material and suppresses gas generation due to corrosion. Furthermore, considering the effect of alloying aluminum and calcium, alloying zinc and zinc alloy powder with aluminum and calcium smoothes the surface of the coated zinc alloy powder that is the negative electrode active material, reduces the reaction surface area, and causes corrosion. It seems that gas generation is suppressed.

[0011]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples. In addition, "%" attached in the following chart
All are by weight unless otherwise specified.

Preparation of zinc alloy powder: A zinc ingot having a purity of 99.995% by weight or more melted at about 500 ° C., and a predetermined amount of tin, bismuth, aluminum and calcium added thereto to obtain a zinc alloy melt. Prepared. Then, these melts were pulverized by a spray method using high-pressure gas, and then these powders were sieved to obtain a zinc alloy powder having a predetermined particle size.

A. A predetermined amount of zinc alloy powder and a predetermined amount of indium particles having a predetermined particle size by this sieving are put into a mixer (rotary drum) equipped with a heating device, and the inside of the mixer is set to a nitrogen atmosphere at 180 ° C. And mixed for 1 hour. By this operation, indium having a melting point of 156.4 ° C. was deposited on the surface of the zinc alloy powder particles to obtain a test zinc alloy powder for use in the present invention.

B. Similarly, a predetermined amount of zinc alloy powder having a predetermined particle size by sieving is put into an aqueous solution in which a predetermined amount of indium salt (indium sulfate or the like) is dissolved, stirred for 30 minutes, and indium is converted into zinc alloy powder by an ion substitution method. Was added to the surface of the particles. The obtained zinc alloy powder was washed with pure water (ion-exchanged water), and then the attached water was replaced with acetone, followed by drying at 45 ° C. for one day to obtain a coated zinc alloy powder for use in the present invention as a test sample. .

Example 1 and Comparative Example 1: First, in order to investigate the discharge performance of the product of the present invention, tin, bismuth, aluminum,
A pure zinc powder having a purity of 99.995% by weight or more that does not contain calcium and indium uniformly alloyed (sample a), and the use of the present invention in which indium is added to the particle surface of the zinc alloy powder according to the above A and B. Coated zinc alloy powder (samples b _A and b _B ) and zinc alloy powder (indium 0.
02 wt%, lead 0.05 wt%, aluminum 0.05
% By weight, 0.6% by weight of mercury (sample c), and pure zinc powder (sample d) were prepared. Then, using these samples, an LR6 type battery shown in FIG. 1 was prepared, and its discharge performance (3.9Ω, 0.9V termination) was measured. The results are shown in Table 1 for comparison.

In FIG. 1, 1 is a positive electrode can, 2 is a negative electrode terminal, 3 is a sealing body, 4 is a negative electrode current collector, 5 is a positive electrode active material obtained by mixing manganese dioxide and graphite under pressure, and 6 is a separator. Reference numerals 7 and 7 are negative electrodes in which an electrolytic solution obtained by saturating zinc oxide in a 40% by weight aqueous solution of KOH is gelled with polyacrylic acid or the like and zinc alloy powder or pure zinc powder is dispersed in the gel. The indium content in the samples a, b _A and b _B was uniformly 0.10% by weight.

[0017]

[Table 1]

As is clear from the results shown in Table 1, when the samples b _A and b _B of the present invention for which indium is added to the particle surface of the zinc alloy powder are used, the samples c are conventionally used. It can be seen that it has the same discharge performance as the case of using the zinc alloy powder which is selectively converted from the existing indium-mercury alloy. Further, there is no difference due to the method of adding indium (difference between A. and B.). The pure zinc powder of sample d and the pure zinc powder of sample a obtained by uniformly alloying indium have inferior discharge performance.

Example 2 and Comparative Example 2: Next, a gas generation test was conducted by changing various alloy compositions of the coated zinc alloy powder for use in the present invention. The gas generation test was performed by dipping 10 g of the coated zinc alloy powder in 5 ml of a saturated KOH aqueous solution having a concentration of 40% by weight as an electrolytic solution and holding the coated zinc alloy powder at 60 ° C. for 30 days. The amount was calculated. The results are shown in Samples 3 to 6 in Table 2. For comparison,
Similar to the case of Example 1 and Comparative Example 1, the same test was carried out for the zinc alloy powder of sample c, the one not containing bismuth, aluminum and calcium, and the one not containing tin. The results are shown together in Samples 1, 2, and 7 in Table 2.

[0020]

[Table 2]

As is apparent from Table 2, sample 1 containing only indium (a sample of pure zinc powder in which the surface of particles was simply added with indium) or sample 2 containing indium and tin was used.
Has a gas generation amount twice as high as that of the sample 7 (sample c) which is a zinc fluoride alloy, but contains indium and tin, and further one or more kinds selected from three kinds of bismuth, aluminum and calcium. It can be seen that the samples 3 to 6 within the scope of the present invention generate less gas than the sample 7 (sample c) which is a zinc hydride alloy.

Example 3 and Comparative Example 3: Next, the alloy composition was changed to various levels in order to examine the good contents of indium, tin, bismuth, aluminum and calcium, and the same as in Example 2 and Comparative Example 2 above. The gas generation test was conducted. The results are shown in FIGS.

In FIG. 2, tin and bismuth are uniformly 0.02% by weight, and indium is added in various levels. FIG. 3 shows the tin content varied at various levels. The indium added to the surface of the particles of this zinc alloy powder was uniformly 0.10% by weight, and the bismuth was uniformly 0.02.
% By weight. FIG. 4 shows that the content of bismuth is changed to various levels, tin is uniformly 0.02% by weight, and indium added and coated on the particle surface of this zinc alloy powder is uniformly 0.10% by weight. Fig. 5 shows that the aluminum content is changed to multiple levels, and tin is uniformly 0.0
The content of indium added to the surface of the particles of this zinc alloy powder was 0.10% by weight. In FIG. 6, the content of calcium is changed to various levels, tin is uniformly 0.02% by weight, and indium added to and coated on the surface of the particles of this zinc alloy powder is uniformly 0.10% by weight.

As is clear from the results shown in FIGS. 2 to 6, the indium content is 0.05 to 0.80% by weight, the tin is 0.005 to 0.05% by weight, and the bismuth is 0.00.
5 to 0.5% by weight, aluminum is 0.01 to 0.05
It can be seen that 0.01% to 0.005% by weight of calcium is in a good range.

[0025]

As is apparent from the above description, the zinc-alkali battery according to the present invention is excellent in corrosion resistance and discharge performance as a battery, even though it does not contain mercury at all, and is quite comparable in practical use as a battery. Absent. Therefore, there is a great contribution to environmental hygiene and resource recycling.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an LR6 type zinc alkaline battery.

FIG. 2 is a graph showing a relationship between an indium content rate and a gas generation amount.

FIG. 3 is a graph showing a relationship between a tin content rate and a gas generation amount.

FIG. 4 is a graph showing a relationship between a bismuth content rate and a gas generation amount.

FIG. 5 is a graph showing a relationship between an aluminum content rate and a gas generation amount.

FIG. 6 is a graph showing a relationship between a calcium content rate and a gas generation amount.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode can 2 Negative electrode terminal 3 Sealing body 4 Negative electrode current collector 5 Positive electrode active material 6 Separator 7 Gelled negative electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masaaki Kurimura 2-18, Keihan Hondori, Moriguchi City, Osaka Prefecture Sanyo Excel Co., Ltd. (72) Inventor Yasuo Akai 2-18, Keihan Hon-dori, Moriguchi City, Osaka Prefecture (72) Inventor Mutsumi Yano 2-18 Keihanhondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (72) Eiichiro Mieno 1443 Nakajuku, Annaka City, Gunma Toho Zinc Co., Ltd. In the laboratory (72) Wataru Sekiguchi 1443 Nakajuku, Annaka-shi, Gunma Toho Zinc Co., Ltd. Technical Research Institute (72) Inventor Junzo Nakagawa 1443 Nakajuku, Annaka-shi, Gunma Toho Zinc Co., Ltd. Technical Research Institute (72 ) Inventor Takanori Akazawa 1443 Nakajuku, Annaka City, Gunma Prefecture Toho Zinc Co., Ltd.

Claims (5)

[Claims] 1. A coated zinc alloy powder obtained by adding indium to the surface of a zinc alloy powder containing tin and further containing at least one selected from bismuth, aluminum and calcium was used as a negative electrode active material. A zinc alkaline battery characterized in that 2. The coated zinc alloy powder has an indium content of 0.05 to 0.80% by weight, and the coated zinc alloy powder has a tin content of 0.005 to 0.05% by weight. The zinc alkaline battery according to claim 1. 3. The zinc alkaline battery according to claim 1, wherein the content of bismuth in the coated zinc alloy powder is 0.005 to 0.05% by weight. 4. The zinc alkaline battery according to claim 1, wherein the content of aluminum in the coated zinc alloy powder is 0.01 to 0.05% by weight. 5. The zinc alkaline battery according to claim 1, wherein the calcium content in the coated zinc alloy powder is 0.01 to 0.05% by weight.