JPS6154152A - Alkaline cell - Google Patents

Abstract

PURPOSE:To prevent the blistering and leakage due to gas generating by forming the negative electrode sealing plate which is consisted of a tripple layered clad plate having its copper layer surface coated with deposite of different kind metals to maintain its higher hydrogen overvoltage so as to fill its internal portion with a negative electrode active material. CONSTITUTION:The sealing plate 4 of a button type alkaline cell, etc., which is used for filling a negative electrode active material 6 placed oppositely to a positive electrode agent 2 through a separator 7, is formed by using a tripple layered clad plate consisted of nickel-stainless steel-copper layer from outside and also, its copper layer surface is formed by using a vacuum evaporation method, etc., so as to have its coated deposite of 0.05-1mg per unit area, which is consisted of metals such as In, Cd, Pb, Sn, etc., to maintain its higher hydrogen voltage. Therefore, enabling the cell to control its hydrogen gas generating from the negative electrode active material 6 nearly perfectly after enclosing the cell, the blistering and leakage of the cell can be prevented.

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 alkaline batteries that use silver oxide, mercury oxide, manganese dioxide, etc. for the positive electrode, zinc for the negative electrode, and alkaline for the electrolyte, the negative electrode side is severely corroded by the electrolyte, and hydrogen gas is generated as a result. Self-discharge could become large. Also, battery damage may occur.

As a countermeasure against this problem, it is safe to maintain a high hydrogen overvoltage, and ice formation using mercury has traditionally been used. The freezing rate at this time is generally 7 to 15% in current technology in order to suppress the generation of hydrogen gas.

However, recently, the problem of mercury pollution has been brought into focus. In response to this, studies are being carried out on alloying negative electrode zinc with other metals to reduce the hydration of zinc, and it is possible to reduce the icing rate to 3-6%. However, by reducing the mercury G:, the zinc hydrate powder comes into contact with copper, which is the inner metal of the negative electrode container, in the presence of an alkaline electrolyte, and the copper surface becomes hydrated. However, this freezing rate varies depending on the amount of hydration in the negative electrode, the area of contact with the zinc hydrate powder and electrolyte, and the surface condition of the inner surface of the negative electrode container, and may be affected by distortion, oxidative corrosion, dirt, and foreign matter adhesion. etc. cannot be completely prevented, hydration is difficult to proceed in that area, and it takes time for hydration to occur, during which time hydrogen gas is observed to be generated from the area where the hydrogen overvoltage is low.

Problems to be Solved by the Invention As a result, hydrogen gas continues to be generated after the battery is sealed, causing swelling and leakage of the battery. The above problem is especially serious in batteries such as small button batteries in which the free volume within the battery is small.

Furthermore, as a recent trend, smaller button batteries have been developed, and in this case, the amount of mercury per negative electrode internal area is reduced, which further accelerates battery blistering and leakage.

The object of the present invention is to solve the above-mentioned problems and provide a stable battery.

Means for Solving the Problems The present invention is an alkaline battery using a negative electrode container having a different metal coated on the inner surface of the negative electrode container to maintain a high hydrogen overvoltage.

Effect: By doing so, hydrogen gas generation from the negative electrode portion can be completely suppressed.

EXAMPLES Below, examples of the present invention will be explained using an alkaline button battery (LRaa type, diameter 11.6 gates, height 6.4 mm) as an example. The figure is a cross-sectional view of the button battery. In the figure, 1 is a positive electrode case, 2 is a positive electrode mixture formed by press-molding a mixture of manganese dioxide and graphite, and the positive electrode ring 3 is tightly attached to the case 1 under pressure. It is something that 4 is a negative electrode sealing plate according to the present invention, which is a three-layer clad plate consisting of nickel-stainless steel-copper layers from the outside, and a metal such as In to maintain a high hydrogen overvoltage on the surface of the copper layer. , Cd, P
At least one of b, Sn, T/, Ag, Ca, Ag, Bi, etc. is applied.

As the coating method X'1, plating, vapor deposition, etc. are used. These methods have the advantage that they can be applied more densely and uniformly. Here, we use the vapor deposition method once a month.

In addition, the coating amount is 0.06 to 18 per unit area.
9 is desirable. The amount of coating is 0.06 da/crt? In the following cases, hydrogen gas generation cannot be completely suppressed. Also, 1m
Although hydrogen gas generation can be completely suppressed when the amount exceeds 100 g, these substances act to suppress the reaction of zinc when the battery is constructed, resulting in a decrease in the negative electrode utilization rate, which has the opposite effect. Therefore, 0.06 to 1 mg is most preferable;
In this example, o and tsmf/al were used. In addition, 2g! If the above are used in combination, apply a total of 0.05 to 1 g/d.

6 is a sealing ring made of nylon and is coupled to 4 to form a negative electrode container. 0.5 to 6 in this container
It houses zinc 6, which is a hydrated negative electrode active material, and an alkaline electrolyte. In the case of a conventional copper layer only, a hydration rate of at least 5% was required to suppress hydrogen gas generation. However, by using the sealing plate of the present invention,
It became possible to completely suppress hydrogen generation at a freezing rate of 0.6%. Even if the inner surface of the negative electrode container is prone to dirt, no hydrogen gas generation is observed even if the amount of mercury is small.

This is because hydrogen gas generation is suppressed not by freezing but by the coated metal. Conversely, when the hydration is set to 0, the effect of the coated gold layer disappears. The reason for this is not clear, but it seems that some kind of synergistic effect was produced. Here, zinc with a freezing rate of 1.6% was used.

ke) 1. The separator 8 is a liquid-containing material.

Note that the electrolytic solution used was one in which ZnO was dissolved in 10M KOH.

Next, the configuration (A) of the present invention and the conventional configuration CB) were evaluated.

The amount of mercury used is 0.1 for (A) when CB) is 1.
5, it decreased to about +.

Next, the number of bulges in the battery when stored at 60°C was examined.

n = 50 As a result, the configuration of the present invention has no problems at all despite the small amount of mercury. On the other hand, with the conventional configuration, blisters were observed from the beginning. The cause of this may be dirt or scratches on the copper layer of the sealing plate, and when it is disassembled and examined,
There was a black discoloration in part of the copper layer, indicating that that part was not sufficiently frozen.

In addition, the following results were obtained in the liquid leakage test.

Conditions T45°C, RH90% n=20 In the present invention (A), no liquid leakage was observed even after 2000 hours. On the other hand, in the conventional configuration [B], leakage was confirmed in 2 out of 20 units after 500 hours.

When this was disassembled and investigated, it was found that the internal pressure increased during disassembly.
The electrolyte was bubbling out and there was clearly gas generation. Furthermore, when the zinc in the negative electrode container was removed and the inner surface of the sealing plate was examined, black discoloration was observed as described above. This is thought to be due to dirt and scratches on the copper layer of the sealing plate, which prevented hydration from progressing sufficiently and hydrogen gas was generated.

In the present invention, by applying metal to the surface of the copper layer, the above-mentioned blistering and leakage were not observed at all.

In this investigation, the effect is greater in smaller batteries and batteries with a smaller absolute amount of mercury relative to the inner area of the sealing plate.

As described above, by coating the inner copper layer of the negative electrode sealing plate with a metal that maintains a high hydrogen overvoltage, it is possible to prevent blistering and leakage due to gas generation, and a battery with stable characteristics can be obtained. It becomes possible.

[Brief explanation of drawings]

The figure is a sectional view of the button-type alkaline battery of the present invention. 1... Positive electrode case, 2... Positive electrode mixture,
3...Positive electrode ring, 4...Sealing plate, 6
... Sealing ring, 6 ... Negative electrode active material,
7...Separator, 8...Liquid-containing material O

Claims (2)

[Claims] (1) The inner surface of the negative electrode container is equipped with a sealing plate made of a copper layer, the surface of the copper layer is coated with at least one metal that maintains a high hydrogen overvoltage, and the negative electrode active material, zinc, is coated on the surface of the copper layer. An alkaline battery filled with electrolyte. (2) In, Cd, Pb, Sn, Tl, A on the surface of the copper layer
2. The alkaline battery according to claim 1, wherein the alkaline battery is coated with at least one member selected from the group consisting of L, Ca, Ag, and Bi.