JPH05190176A - Non-amalgamated zinc alloy powder for alkaline battery having small gas generation quantity - Google Patents

Abstract

PURPOSE:To permit the use as negative electrode active material for alkaline battery which does not contain lead as alloy component and is not amalgamated but can be practically used. CONSTITUTION:Zinc alloy powder consists of lead up to 0.001wt.%, 0.005-0.5wt.% Bi, 0.005-0.5wt.% In, 0.005-0.5wt.% metal which is selected from Al and Ca, and Zn and inevitable impurities as rest.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zinc alloy powder for alkaline batteries having improved properties, and particularly to anhydrous silver (hereinafter
The present invention relates to a zinc alloy powder with a small amount of gas generation, which is characterized by being free of lead) and low lead.

[0002]

2. Description of the Related Art Conventionally, zinc or a zinc alloy has been used as a negative electrode material for batteries such as alkaline dry batteries. Zinc has been used as a negative electrode material because it has a high hydrogen overvoltage and is relatively inexpensive, but using zinc alone sufficiently suppresses the generation of a large amount of hydrogen gas during battery use. It is difficult to do so, and problems such as electrolyte leakage have arisen.

For the purpose of solving these problems, zinc is selectively used as an effective method for suppressing gas generation, which has been widely performed in recent years. However, since this method involves serious pollution problems when disposing of waste dry batteries, it has become necessary to develop a zinc alloy that achieves a desired effect in a consistent manner. The present inventors have made some progress in developing such a zinc alloy as disclosed in JP-A-63-304571 "Zinc alloy for battery and method for producing the same".

[0004]

It is effective to add lead to the zinc alloy in order to suppress the gas generation without making it unfavorable. However, lead, like mercury, has a problem in terms of pollution. Therefore, it is inevitable that a low-lead zinc alloy powder will be requested in the future.

[0005]

Means for Solving the Problems In order to solve the above problems, the inventors of the present invention have conducted extensive studies and found that a lead-free alloy was used as a zinc alloy powder for use in alkaline batteries.
Moreover, it has been found that a zinc alloy powder for alkaline batteries, which produces a small amount of hydrogen gas while remaining unconstrained, can be obtained.

That is, the object of the present invention is to provide a novel lead-free zinc alloy powder which produces a smaller amount of hydrogen gas than conventional zinc alloy powders even when used as a negative electrode material for batteries and the like without any modification. 0.001 to less than 0.001% by weight of lead, 0.005 to 0.5% by weight of bismuth, 0.005 to 0.5% of indium.
% By weight, 0.005 to 0.5% by weight of at least one kind of metal selected from aluminum and calcium, and the balance consisting of zinc and unavoidable impurities, and it can be used as a negative electrode active material of a practical alkaline battery without making any changes. TECHNICAL FIELD The present invention relates to a zinc alloy powder, that is, a smoothed zinc alloy powder for alkaline batteries.

[0007]

The zinc alloy powder of the present invention can be produced by mixing and melting a predetermined amount of a specific alloying element, zinc and unavoidable impurities to form an alloy, and then forming the powder by a spraying method. Can be used as it is as a negative electrode active material of an alkaline battery. In this case, the mechanism of action of these specific additive elements has not been sufficiently clarified, but indium and bismuth contained in the zinc alloy have an action of increasing hydrogen overvoltage, while aluminum and calcium are zinc alloys. Because it has the effect of smoothing the surface,
It is considered that the total effect of these decreases the surface area of the alloy powder and improves the corrosion resistance. Therefore, the zinc alloy powder of the present invention is obtained as a zinc alloy powder that produces a small amount of hydrogen gas due to the synergistic effects of these actions.

The present invention will be described in detail below with reference to examples.

[0009]

Example 1 Various zinc alloys having the compositions shown in Table 1 were manufactured as powders having a particle size of 35 to 150 mesh by a usual spraying method, and a certain amount of the obtained zinc alloy powder was put into a KOH solution to remove mercury. 40% K at 60 ℃, saturated with zinc oxide, one with 0.15% by weight added and the other with no addition
It was immersed in an OH solution and the amount of hydrogen gas generated was measured and evaluated. The results are shown in Table 1. Hydrogen gas generation rate (μl /
g.day) is the amount generated per day per 1 g of alloy powder.

[0010]

[Table 1]

From these results, there is almost no difference in the amount of hydrogen generated between the zinc alloy powder having the same composition and 0.15% by weight of mercury, and the unhydrolyzed product according to the present invention. It has been found that it is sufficiently possible to manufacture and use a mercury-free battery as a battery replacement.

[0012]

Example 2 Various zinc alloys according to the present invention shown in Table 2,
A comparative alloy obtained by adding 0.05% by weight of lead to the zinc alloy was treated in the same manner as in Example 1 to measure and evaluate the hydrogen gas generation amount, and the results are shown in the same table.

[0013]

[Table 2]

From these results, the alloy having the composition of the present invention has a difference in the amount of hydrogen generation compared with the conventional lead-containing zinc alloy powder even without adding lead, which usually has a great effect on the suppression of hydrogen generation. Turned out not to.

[0015]

According to the present invention, as described above, the obtained zinc alloy powder is a lead-free or low-lead (because it contains Pb as an impurity) alloy, and it is also free of negative electrode material for alkaline batteries. Since the amount of gas generation can be sufficiently suppressed by using as a material, it is possible to manufacture a practical alkaline battery using a zinc-free unalloyed powder, that is, a non-silver battery. If such a battery is manufactured and used, the pollution advantage will be immeasurable.

Continuation of the front page (72) Inventor Hiroshi Ogawa 1-2-8 Marunouchi, Chiyoda-ku, Tokyo Dowa Mining Co., Ltd.

Claims (1)

[Claims] 1. Lead less than 0.001 wt% and bismuth 0.00
5% to 0.5% by weight, 0.005% to 0.5% by weight of indium, 0.005% to 0.5% by weight of at least one metal selected from aluminum and calcium, and the balance consisting of zinc and unavoidable impurities. A non-alloyed zinc alloy powder for alkaline batteries that can be used as a negative electrode active material for batteries.