JPH0619995B2 - Zinc alkaline battery - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a zinc alkaline battery, more specifically selected from cobalt, lead, cadmium, thallium and indium.
The present invention relates to a zinc-alkaline battery in which a zinc alloy containing at least one species in a specific range is used as it is or after being used as a negative electrode active material for a battery.

(Background of the Invention) In an alkaline battery or the like using zinc as a negative electrode active material, a strong alkaline electrolyte such as an aqueous potassium hydroxide solution is used, and therefore the battery must be sealed. This sealing of the battery is particularly important for miniaturization of the battery, but at the same time, it confine hydrogen gas generated by corrosion of zinc during battery storage. Therefore, the gas pressure inside the battery increases during long-term storage, and there is a danger of explosion and the like if the sealing is perfect.

As a countermeasure against this, research has been conducted to prevent corrosion of zinc, which is the negative electrode active material, to reduce the generation of hydrogen gas inside the battery, and to use zinc hydride, which utilizes the hydrogen overvoltage of mercury, as the negative electrode active material. Has been done. For this reason, the negative electrode active materials for alkaline batteries that are commercially available today contain a large amount of mercury of about 5 to 10% by weight, and as a social need, the development of batteries with lower mercury or mercury-free batteries is required. It has become strongly expected.

Therefore, various proposals have been made regarding a zinc alloy powder in which various metals are added to zinc in order to reduce the mercury content in the battery. For example, there is a zinc alloy powder in which lead is added to zinc, or a zinc alloy powder in which lead and indium are added to zinc by the present inventors (JP-A-58-181266). However, although these zinc alloy powders have some gas generation suppressing effect, they are not yet sufficient.

As described above, a battery that reduces the amount of hydrogen gas generated while keeping the zinc alloy powder, which is the negative electrode active material, at a low level and maintains the discharge performance, which is the battery performance, at a high level has not yet been obtained.

(Object of the Invention) In view of the present circumstances, the present invention provides a zinc-alkaline battery using a negative electrode active material that significantly reduces the content of mercury, suppresses hydrogen gas generation, and maintains discharge performance at a high level. The purpose is to do.

(History of the Invention) As a result of intensive research aimed at achieving this object, the present inventors have added to a negative electrode active material made of zinc, one or more selected from cobalt and lead, cadmium, thallium, and indium in a specific range. According to the present invention, it is found that the synergistic effect of these additional elements further reduces the hydrogen gas generation amount as compared with the conventional low-alloyed zinc alloy powder, and that a zinc alkaline battery having excellent discharge performance can be obtained. Reached

(Structure of the Invention) That is, in the present invention, 0.01 to 0.5% by weight of cobalt, 0.01 to 0.5% by weight of lead, and the total amount of at least one selected from cadmium, thallium, and indium is 0. .0
A zinc alkaline battery is characterized by using a zinc alloy containing 1 to 0.5% by weight as a negative electrode active material.

In the present invention, the zinc alloy to which a specific amount of at least one selected from cobalt, lead, cadmium, thallium, and indium is added is used as the negative electrode active material as it is, or after the zinc alloy is selectively used, it is used as the negative electrode active material. The mercury content in the case of conversion is less than the mercury content of the conventional negative electrode active material, that is, less than 5.0% by weight, but if the conversion rate is lowered and low pollution is considered, it is 3 0.0% by weight
It is the following. Further, it is possible to suppress gas generation even with a small amount of around 1.0% by weight or less.
In particular, in an air battery provided with an exhaust mechanism, a zinc alkaline battery provided with a hydrogen absorption mechanism, and the like, the permissible hydrogen gas generation amount is relatively large. Therefore, when the present invention is applied to such a battery, 1. A zinc alloy having a low weight reduction rate of 0% by weight or less or a weight loss-free zinc alloy is preferably used as the negative electrode active material.

The zinc alloy used in this negative electrode active material has a cobalt content of 0.01 to 0.5% by weight and a lead content of 0.01 to 0.5% by weight.
0.5% by weight, the total content of at least one selected from cadmium, thallium and indium is 0.01 to 0.5.
Addition effect is demonstrated with a small amount of wt%. If the content of one or more selected from cobalt and lead and cadmium, thallium, and indium is less than the respective lower limits, the effect of the present invention cannot be obtained, and if the content exceeds the upper limit, self-discharge proceeds like zinc containing impurities. However, good results cannot be obtained for suppressing gas generation and discharging performance.

Although the action effect of each of these additional elements has not been sufficiently clarified, it is presumed that the cobalt contained in the zinc alloy is a metal having corrosion resistance in itself,
It is also considered to be useful for suppressing local corrosion reaction when it is solutionized with zinc. Also lead or cadmium, thallium,
It is considered that indium has a function of increasing hydrogen overvoltage or a function of suppressing corrosion of zinc in the alkaline electrolyte.

The present invention provides a zinc alloy having good corrosion resistance without deteriorating discharge characteristics due to the synergistic effect of each of these actions.

Thus, the zinc-alkaline battery of the present invention uses caustic potash as an electrolytic solution, an aqueous alkaline solution containing caustic soda as a main component, the above-mentioned zinc alloy or delayed zinc alloy as the negative electrode active material, and manganese dioxide as the positive electrode active material. It can be obtained by using silver oxide, oxygen or the like.

(Explanation of Examples) Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples.

Examples 1 to 10 and Comparative Examples 1 to 11 Zinc ingots having a purity of 99.997% or more are melted at about 500 ° C., and the contents of cobalt, lead and cadmium are each 0.05% by weight as shown in Table 1. To make a zinc alloy, and add this to high pressure argon gas (jet pressure 5 kg /
It was pulverized using cm ² ). Next, mercury was added to the above powder in an alkaline solution of 10% potassium hydroxide so as to be 1.0% by weight to perform a grading treatment to obtain a zinc alloy powder (Example 1).

In addition, as shown in Table 1, 1) 0.05 wt% cobalt, 0.05 wt% lead, 0.05 wt% thallium (Example 2) 2) 0.05 wt% cobalt with the following compositions, respectively: , Lead 0.05% by weight, indium 0.05% by weight (Example 3) 3) cobalt 0.01% by weight, lead 0.01% by weight, cadmium 0.01% by weight (Example 4) 4) cobalt 0 0.01 wt%, 0.01 wt% lead, 0.01 wt% thallium (Example 5) 5) 0.01 wt% cobalt, 0.01 wt% lead, 0.01 wt% indium (Example 6) 6) 0.5 wt% cobalt, 0.5 wt% lead, 0.5 wt% cadmium (Example 7) 7) 0.5 wt% cobalt, 0.5 wt% lead, 0.5 wt% thallium ( Example 8) 8) Cobalt 0.5% by weight, lead 0.5% by weight, indium 0. Wt% (Example 9) 9) Cobalt 0.5 wt%, Lead 0.5 wt%, Cadmium 0.1 wt%, Thallium 0.1 wt%, Indium 0.3 wt% (Example 10) 10) Cobalt 0.05 wt% (Comparative Example 1) 11) Cobalt 0.05 wt%, Lead 0.05 wt% (Comparative Example 2) 12) Cobalt 0.05 wt%, Cadmium 0.05 wt% (Comparative Example 3) ) 13) Cobalt 0.05% by weight, thallium 0.05% by weight
(Comparative Example 4) 14) 0.05 wt% lead, 0.05 wt% indium (Comparative Example 5) 15) 0.05 wt% cobalt, 1.0 wt% lead, 0.05 wt% cadmium (Comparative Example) 6) 16) 0.05 wt% cobalt, 0.05 wt% lead, 0.005 wt% cadmium (Comparative Example 7) 17) 10 wt% cobalt, 0.05 wt% lead, 0.05 wt% cadmium ( Comparative Example 8) 18) 0.005 wt% cobalt, 0.05 wt% lead, 0.05 wt% cadmium (Comparative Example 9) 19) 0.05 wt% cobalt, 0.05 wt% lead, 1. 0% by weight (Comparative Example 10) 20) A zinc alloy composed of 0.05% by weight of cobalt, 0.05% by weight of lead, and 1.0% by weight of indium (Comparative Example 11) was prepared. The powder is pulverized by a method and subjected to a grading treatment to obtain a mercury content of 1.0% by weight. Alloy powder (Examples 2 to 10 and Comparative Examples 1 to 11) was obtained.

A hydrogen gas generation test was performed using the zinc alloy powder thus obtained, and the results are shown in Table 1. In the gas generation test, 5 ml of a 40 wt% aqueous potassium hydroxide solution saturated with zinc oxide was used as an electrolyte, and 10 g of zinc alloy powder was used at 45 ° C. for 50 days to generate a gas (ml). / G) was measured.

In addition, the battery performance was evaluated using the alkaline manganese battery shown in FIG. 1 with these zinc alloy powders as the negative electrode active material. The alkaline manganese battery of FIG. 1 includes a positive electrode can 1, a positive electrode 2, a negative electrode 3, a separator 3, a sealing body 5, a negative electrode bottom plate 6,
Negative electrode current collector 7, cap 8, heat-shrinkable resin tube 9,
It is composed of insulating rings 10 and 11 and an outer can 12. Using this alkaline manganese battery, the discharge duration to a final voltage of 0.9 V was measured under a discharge negative electrode of 4Ω and a discharge condition of 20 ° C., and the measured value of Comparative Example 12 described below using a conventional negative electrode active material was set to 100. It was shown by the index. The results are shown in Table 1.

Comparative Example 12 In the same manner as in Example 1, a zinc halide alloy powder which has been conventionally used, in which 5.0% by weight of mercury is added to zinc (Comparative Example
12) got. This was subjected to a hydrogen gas generation test and a battery performance test in the same manner as in Example 1, and the results are shown in Table 1.

As shown in Table 1, Example 1 in which zinc halide alloy powder prepared by adding specific amount of one or more kinds selected from cobalt, lead, cadmium, thallium, and indium to zinc was used as a negative electrode active material -10, compared with Comparative Example 12 using a negative electrode active material conventionally used zinc hydride alloy powder that is added only mercury to Comparative Examples 1-11 and zinc, hydrogen gas generation suppression effect is large, It can be seen that the discharge performance is also excellent.

(Effects of the Invention) As described above, the zinc of the present invention used as a negative electrode active material as a zinc alloy containing cobalt and lead and at least one selected from cadmium, thallium and indium in a specific range as it is or after being selectively used. The alkaline battery can improve the battery performance while suppressing the hydrogen gas generation rate, and has a low content rate of mercury or does not contain mercury, and thus meets social needs. Therefore, the zinc alkaline battery of the present invention can be used in a wide range of applications.

[Brief description of drawings]

FIG. 1 shows a 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: Outer can

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Ryoji Okazaki 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Kanji Takada 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Akira Miura 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A total amount of at least one selected from cadmium, thallium, and indium is 0.01 to 0.5% by weight, 0.01 to 0.5% by weight of cobalt, 0.01 to 0.5% by weight of lead.
A zinc alkaline battery comprising a zinc alloy containing 5% by weight as a negative electrode active material. 2. The zinc alkaline battery according to claim 1, wherein the zinc alloy is modified.