JPH0356637A - Zinc alloy for alkaline battery electrode - Google Patents

Abstract

PURPOSE:To obtain the zinc alloy for a battery electrode having less generation of hydrogen gas and having good discharging battery capacity by adding specified amounts of Ga, In, Pb and Al to high purity zinc in which the contents of Ni, Cr, Mo, Sn, Sb and Fe are regulated. CONSTITUTION:High purity zinc of, by weight, >=99.995% zinc purity constituted of each <=1ppm Ni, Cr, Mo, Sn and Sb is incorporated with 0.001 to 0.01% Ga, 0.01 to 0.05% In, 0.01 to 0.1% Pb and 0.01 to 0.06% Al, according to necessary, which is mercurated into <=1.0% Hg concn. to obtain the zinc alloy for an alkaline battery electrode. The zinc alloy has less generation rate of hydrogen gas at the time of storing and less dispersion thereof in the state of low concn. mercuration or unmercuration, furthermore has good discharging battery capacity and can stably be obtd. at low production cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a Ga-1n-Pb-/l-zinc based zinc alloy for alkaline battery electrodes, which has good corrosion resistance.

[Conventional technology]

Zinc or zinc alloys used in the negative electrode of alkaline batteries are used to prevent battery containers from deforming or leaking due to corrosion caused by electrolyte and the resulting hydrogen gas during battery use and battery storage. What is needed is something that does not

Since zinc has a relatively high hydrogen overvoltage and is relatively inexpensive, it has been used as a material for battery electrodes for a long time. It is difficult to suppress hydrogen overvoltage to a certain extent, and in order to further increase hydrogen overvoltage and suppress corrosion,
Zinc has been powdered with 6-10% by weight of mercury.

After that, environmental pollution caused by mercury became a problem, and from the viewpoint of pollution prevention, efforts were made to reduce or eliminate the permanence of zinc, and alternative elements for mercury were studied.

Up to now, zinc-based alloys that are effective in increasing the corrosion resistance of zinc include, for example, Ga-In-P.
b-zinc alloy (JP-A-58-26456, JP-A-59)
-121780), In-Pb-Af-zinc alloy (JP-A-61-77265) or Ga-In-Pb-
Zinc alloys such as Af-zinc alloy (JP-A-61-253339) have been proposed or put into practical use.

Problems to be solved by the invention C] However, in the In-Pb-zinc alloy,
Although the effect of increasing the hydrogen overvoltage of zinc and suppressing corrosion is clearly seen, the rate of hydrogen gas generation varies widely, and products produced for practical use as alkaline battery electrodes have failed at the inspection stage. There are quite a few production outlets, which means that the supply of material for battery electrodes is not stable, which increases production costs.

Furthermore, on the other hand, if we try to improve the corrosion resistance of a material alloy to such an extent that variations in the rate of hydrogen gas generation can be ignored, the problem arises that the discharge performance of the battery deteriorates due to the non-(II) state of the material alloy. That is, in the past, in order to maintain such corrosion resistance and battery performance, a filtration concentration of 1.5% by weight or more was still required.

In view of the above circumstances, the present invention further provides low hydrogen gas generation rate during storage, less variation, and good discharge battery performance in a low-concentration permanent state or non-permanent state. The purpose of the present invention is to develop a zinc alloy for alkaline battery electrodes that can be produced stably and therefore reduce production costs.

[Means to solve the problem]

In order to achieve the above object, the present invention provides that Ni, Cr, Mo, Sn and Sb as impurities are each single ffi
G
a O. 001 to 0.01% by weight, InO. 01
~0.05 wt%, Pb0.01-0.1 wt% and A
A zinc alloy for alkaline battery electrodes containing f 0.01 to 0.06% by weight, furthermore, the zinc alloy containing Hg1.
We propose a zinc alloy for alkaline battery electrodes that has a concentration of less than 0% by weight. [Function] The additive elements In and Pb are the main elements that improve the corrosion resistance of zinc and reduce the amount of hydrogen gas generated under the coexistence of Ga and Affi, and each is less than 0.01% by weight. The effect is small, and even if In exceeds 0.05% by weight and Pb exceeds 0.1% by weight, the effect does not increase and is uneconomical. Furthermore, the additive element Ga
and A1 are elements useful for enhancing the corrosion resistance effect and suppressing the deterioration of discharge battery performance in coexistence with In and Pb, Ga being less than 0.001% by weight and Al being 0.00% by weight.
The effect is not significant when the content of Ol is less than 0.01% by weight and the content of Al exceeds 0.06% by weight, but the effect does not increase and is rather uneconomical. be.

Impurities contained in zinc accelerate the corrosion of zinc, and when the purity of zinc is less than 99.995%, especially the impurity Ni
, Cr, Mo, Sn, and Sb each exceed 1 ppm by weight, or when Fe exceeds 10 ppm by weight, the amount of hydrogen gas generated increases to the extent that the influence cannot be ignored, and also becomes a cause of variation. ．． [Example] Hereinafter, the present invention will be specifically explained with reference to Examples and Comparative Examples.

Zinc purity 99. 995% by weight or more, Ni, Cr, M
The content of o, Sn and Sb is 1 ffipppm each.
In the following, zinc alloy particles with a particle size of 48 to 150 mesh are produced by a gas injection method from a molten metal made by adding Ga, In, Pb, and A2 as alloy components using high-purity zinc with an Fe content of less than 10 ppm by weight. Manufactured.

Further, the zinc alloy particles were stirred in a 10% by weight KOH aqueous solution to activate the surface of the zinc alloy particles, and mercury was added dropwise to produce Yonghwa zinc alloy particles. The obtained zinc alloy particles of the present invention are shown in Table 1 as Samples 1 to 21.

Next, these zinc alloy particles were immersed in a 40% by weight KOH aqueous solution at 60°C saturated with zinc oxide to measure the amount of hydrogen gas generated for 20 days. We prototyped a battery with the same structure as a commercially available LRS type alkaline manganese battery using zinc alloy grains as the negative electrode active material, and under strong discharge conditions of 20'C with a discharge load of 2Ω, we were able to discharge to a final spiritual pressure of 0.9■. The duration was measured. The results are also shown in Table 1.

Table 1 In addition, the amount of hydrogen gas generated was measured using the same method as in the above example for a zinc alloy with a permanent concentration of 1.5% by weight, which is used in the electrodes of LRB type alkaline manganese batteries currently on the market. 40μ1/g, and the discharge duration was 13
It was 0 win.

Table 2 shows zinc alloy grains manufactured by the same method using the same high-purity zinc as in the above-described example as Comparative Samples 1 to 16, except that the alloy composition was outside the scope of the present invention. It was shown to.

Next, the hydrogen gas generation amount of these zinc alloy particles was measured by the same method as in the above example, and the battery performance was evaluated based on the 2Ω strong discharge duration.

The results are also shown in Table 2. Table 2 North 4u Coarse 4 Zinc alloy grains produced by the same method as in the above example except that the content of impurities was outside the range of the present invention are shown in Table 3 for comparison samples 17 to 4. It was shown as 28.

Next, the amount of hydrogen gas generated was measured for these zinc alloy grains by the same method as in the above example.

The results are also shown in Table 3.

Table 3 As shown in the results of the Examples in Table 1 and the Comparative Examples in Tables 2 and 3, the zinc alloy of the present invention has a 1.5% Compared to the case of zinc chloride alloy, the distribution of hydrogen gas generation rate is slightly higher,
Even so, in the range of 40 to 100 μl/g, it shows a tendency to decrease depending on the alloy component content, and when the etching concentration is kept constant, it is stable with little variation.

Further, the zinc alloy of the present invention exhibited a high discharge duration of 130 IIIin even under a strong discharge load condition of 2Ω. This value of 130+min indicates the result when zinc in the electrode material is used effectively. Although the reason is unknown, the Ga-In-Pb of the present invention
-1! In the single-zinc alloy, in the low aging range of 1.0% by weight or less, the amount of hydrogen gas generated decreases depending on the degree of permanentization, but the characteristic is that the amount of hydrogen gas generated is even smaller in the non-permanent state. ．． As in the case of Comparative Example 1 shown in Table 2, the alloy fraction In
and pb are the lower limit of the invention alloy &[l {i0
．． When the amount is less than 0.01% by weight, the amount of hydrogen gas generated increases rapidly and the discharge duration also decreases slightly.

In addition, as for Ga and Af, when the lower limit of the present invention alloy Mi precept is 0.001% by weight and 0.01% by weight, respectively, the amount of hydrogen gas generated does not change much, but the discharge duration sharply decreases. Battery performance deteriorates. On the other hand, even if the alloy components Ga, In, Pb, and Af are contained in amounts exceeding the upper limit of the alloy composition of the present invention, the amount of hydrogen gas generated does not substantially change, and the battery performance as indicated by the strong discharge duration improves. Since there is no hope of doing so, it is rather uneconomical. Oh, comparative sample N1
As seen in the case of lLl-Nα8, when any alloy component is less than the lower limit, Hg 1.0% by weight
Although there is a tendency for improvement in the non-permanent state than in the low-permanence state, there is no difference in terms of problems in hydrogen gas generation amount or battery performance. Furthermore, as shown in Table 3 for Comparative Example 2, the Ni, Cr, Mo, Sn,
If the impurities Sb and Fe are contained in an amount exceeding the upper limit of the present invention, the amount of hydrogen gas generated will be determined by the measuring instrument regardless of whether the Hgl is in a low aging state of 0% by weight or in an ice-free state. The amount rapidly increases to exceed the capacitance limit of 300 μl/g, making it unusable.

As described above, the present invention provides Ni, Cr, Mo, Sn, S
impurities such as b and Fe are regulated within the range stated in the claim,
By limiting the alloy components consisting of Ga, In, Pb, and AN to the ranges described in the claims, the coexistence effect of these elements has been sufficiently improved, so that the corrosion resistance of zinc can be improved in low aging or non-icing conditions. This makes it possible to maintain a high level of discharge battery performance.

(Effects of the Invention) As is clear from the above description, according to the present invention, the amount of hydrogen gas generated is small and there is little variation even when the concentration is reduced to zero or less than 1.0% Hg. Furthermore, since good discharge battery performance can be maintained and stable production can be achieved, it is possible to provide a zinc alloy for alkaline battery electrodes that can suppress production costs.

Claims (2)

[Claims] (1) High-purity zinc containing Ni, Cr, Mo, Sn, and Sb of 1 ppm or less by weight, and 10 ppm or less of Fe, and a zinc purity of 99.995% by weight or more, with 0.0% Ga added. 001-0.01% by weight, In 0.01
A zinc alloy for an alkaline battery electrode, characterized in that it contains 0.05% by weight of Pb, 0.01% to 0.1% by weight of Pb, and 0.01% to 0.06% by weight of Al. (2) A zinc alloy for an alkaline battery electrode, characterized in that the zinc alloy according to claim (1) is aqueousized to a Hg concentration of 1.0% by weight or less.