JPS6161364A - Alkaline battery - Google Patents

Abstract

PURPOSE:To retard hydrogen gas evolution and increase leakage resistant ability to stabilize performance of an alkaline battery by alloying a copper layer inside a negative container with a metal which increases hydrogen overvoltage. CONSTITUTION:A negative container of an alkaline battery is formed by a three layer clad plate comprising nickel, stainless steel, and copper in order from the outside. The copper layer is alloyed with one or more of In, Cd, S, Tl, Pb, Ca, Ag, and Bi to increase hydrogen overvoltage. The amount of metal for alloying is preferable to limit to 100-1,000ppm. By using this negative container in an alkaline battery, total amount of mercury in the battery can be reduced. Even if zinc powder having 0.5wt% Hg is used, hydrogen gas evolution is retarded to obtain a steady alkaline battery.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a negative electrode container for an alkaline battery.

Conventional technology In so-called alkaline batteries, which use silver oxide, mercury oxide, manganese dioxide, etc. for the positive electrode, zinc for the negative electrode, and an alkaline aqueous solution for the electrolyte, the zinc in the negative electrode is corroded by the alkaline electrolyte, and as a result, The generation of hydrogen gas caused self-discharge to increase, and in some cases caused swelling and battery explosion.

As a countermeasure for this, it is necessary to maintain a high hydrogen overvoltage of the negative electrode zinc.

For this purpose, a method has been used so far to add mercury to zinc and treat it with ice. Generally, the freezing rate used is 7 to 15 wt% based on zinc.

However, recently, the issue of mercury has come under the spotlight again.

Problems to be Solved by the Invention In order to reduce the freezing rate in response to this, studies have been carried out on alloying negative electrode zinc with different metals, and the freezing rate has been reduced to 3 to 5.
It became possible to lower it to wt%. However, by reducing the amount of mercury, the frozen zinc powder comes into contact with the copper layer on the inner surface of the negative electrode container in the presence of an alkaline electrolyte, and the surface of this copper layer is made permanent, but the freezing rate is It varies depending on the amount of frozen zinc, the contact area between the frozen zinc powder and the electrolyte, the surface condition of the copper layer on the inside of the negative electrode container, etc., and even if you look only at the negative electrode container, physical distortion, oxidative corrosion, dirt, and foreign matter adhesion can occur. It is not possible to completely prevent such problems, and the hydration of the affected area is extremely delayed. Furthermore, it took time for complete ice to form, and during that time hydrogen gas was observed to be generated from areas where the hydrogen overvoltage was low.

As a result, hydrogen gas continues to be generated even after the battery is sealed, causing the battery to swell and leak.

This problem becomes particularly serious in batteries where the free volume within the battery is small, such as small button batteries.

In addition, due to the recent tendency for devices to be shorter, thinner, lighter, and smaller, smaller button batteries have been developed, and in this case, the total amount of mercury is also extremely small. Then, the smaller 11130 size is 0.5. For R1120 size, the ratio is 025.

Therefore, the amount of mercury is even lower in the 726 size shed. Therefore, there was a problem in that the swelling and leakage of the battery were further accelerated.

The present invention aims to solve the above-mentioned problems and provide a more stable alkaline battery.

Means for Solving the Problems The present invention uses a copper layer alloyed with at least one metal capable of increasing the hydrogen overvoltage in order to maintain a high hydrogen overvoltage in the copper layer on the inner surface of the negative electrode container.

The details of the present invention will be explained using an LR4aR44 size Caliper button battery (diameter 11,811. height 6.4 gm) as an example.

The figure is a partial cross-sectional view of this button battery. In the figure, 1 is a positive electrode container, and 2 is a positive electrode made of a pressure-molded mixture of manganese dioxide and graphite, which is tightly pressed into the container 1 together with a positive electrode ring 3. It is. 4 is a negative electrode container that is a feature of the present invention;
It consists of a three-layer clad plate of nickel-stainless steel-copper from the outside, and the inner copper layer is made of a metal such as In, Cd, Sn, TI, Pb, AI, Ca to increase the hydrogen overvoltage.
, Ag, Bi Alloyed with at least one member selected from the group 0.

The amount of metal added for alloying is preferably 1100PP to 1ooQpPM. The amount added is 1100PP
If it is less than that, the generation of hydrogen gas cannot be completely suppressed. Furthermore, although hydrogen gas generation can be completely suppressed if the amount is as large as 11,000 PP, these substances come to suppress the reaction of zinc during battery construction, resulting in a decrease in the negative electrode utilization rate and having the opposite effect. Therefore, the result of consideration is 100-1
It can be said that 1000PP is the most preferable. The same thing can be said even if two or more metals to be alloyed are added. The total amount added is 100 to 11,000P.
Let it be P. Here, a ternary alloy of copper-In-Pb is used,
The amount of addition is In 300 PPM, Pb
3ooPPM and the total amount added was eooPPM.

5 is a sealing roll made of nylon, which is coupled to the negative electrode container 4. A 0.5 potash electrolyte is stored in this container.

In conventional batteries, the amount of mercury needs to be at least 6 to 7 wt% in order to suppress hydrogen gas generation, but in the present invention, it is possible to suppress hydrogen gas generation even when hydration is o, swt%. Ta. Further, even if there is dirt on the inner surface of the sealing plate, there is no problem, and since the copper layer has a high hydrogen overvoltage, no generation of hydrogen from the inner surface of the negative electrode container is observed even if the amount of mercury is small. 7 is a separator, and 8 is a liquid-containing material.

Effect This is because hydrogen gas generation is not suppressed by freezing the inner surface of the negative electrode container, but by alloying a metal with a high hydrogen overvoltage with copper. When Totoro changes the freezing of zinc, which is the negative electrode active material, to O, the effect of the alloy disappears. Although the cause of this is not clear, it is thought that a synergistic effect between mercury and alloying occurred in some way.

Example The battery of the present invention has a structure shown in the figure, and the ice formation rate is 1.6% using zinc as the negative electrode active material, and the electrolyte is a solution of 10M KOHjCZnO. , Battery B in which the inner surface of the negative electrode container was made of only copper was evaluated.

Although the pollution of mercury has become a problem, it has become possible to reduce the amount of mercury actually used by battery manufacturers to about 100 times the amount of B.

In addition, when both batteries were stored at 60°C, the number of bulges in the batteries was investigated and the results were as shown in Table 1.

Table 1 n=s.

As a result, no problems were observed in the battery engineer of the present invention, even though the amount of mercury used was as small as in Job B. On the other hand, in conventional battery B, swelling of the battery was confirmed from the beginning. The cause of this is thought to be dirt, scratches, etc. on the copper layer of the negative electrode container, and when it was disassembled and examined, a part of the copper layer was found to have black discoloration. It seems that sufficient ice formation did not occur in that area.

Also, the results shown in Table 2 were obtained in the liquid leakage test. The storage conditions were a temperature of 46° C. and a relative humidity of 90%.

Table 2: n=20 In the battery of the present invention, no leakage was observed even after 2000 hours. When this battery was disassembled, the copper layer of the sealing plate in contact with the nylon ring was not discolored at all, and no electrolyte was detected. Furthermore, the condition of the negative electrode zinc remained as it was at the initial stage, and there was no black discoloration or blocking phenomenon of zinc due to mercury.

On the other hand, in conventional battery B, leakage was confirmed in 2 out of 20 batteries after the SOO time elapsed. When this battery was disassembled, an increase in internal pressure was observed, and the electrolyte was blown out, causing obvious gas generation. . Furthermore, when looking at the copper layer on the inner surface of the negative electrode container, there was a black discoloration as described above. This is because there are parts of the copper layer where icing has not progressed sufficiently due to dirt, scratches, etc.
This is where hydrogen gas is generated.

In the present invention, there was no blistering or leakage as described above.

According to the present invention, it is possible to develop even smaller button batteries, and the effect becomes even more remarkable in batteries where the absolute amount of mercury is small relative to the area of the negative electrode container.

As described above, by alloying the copper layer on the inner surface of the negative electrode container with a metal that can increase the hydrogen overvoltage, the total amount of mercury used can be significantly reduced compared to the past.

■ Prevents battery swelling due to gas generation.

■ Improved leakage resistance.

Alkaline batteries with stable characteristics can be obtained.

[Brief explanation of drawings]

The figure is a sectional view of an alkaline battery according to the present invention. 1...Positive electrode container, 2...Positive electrode, 3...
...Positive electrode ring, 4...Negative electrode container, 6...
... Sealing ring, 6... Negative electrode active material, a.
... Separator, 8 ... Liquid-containing material.

Claims (2)

[Claims] (1) An alkaline battery in which the inner surface of a negative electrode container containing a negative electrode active material mainly composed of zinc is made of a copper layer, and the copper layer is alloyed with at least one metal that increases hydrogen overvoltage. (2) The alkaline battery according to claim 1, wherein the metal alloyed with copper is at least one selected from the group consisting of indium, cadmium, lead, tin, thallium, calcium, silver, and bismuth. .