JPH0620693A - Alkaline battery - Google Patents

Abstract

PURPOSE:To provide an alkaline battery which can suppress the hydrogen gas generation in the battery, even when mercury is not added, and prevents performance deterioration. CONSTITUTION:In an alkaline battery containing no mercury, since the surface of a negative electrode collector 7 at least making contact with a gelled zinc 5 is plated with indium, and then heated in inert gas atmosphere or vacuum, working stress is removed, and the surface is smoothed. Therefore, hydrogen gas generation can be suppressed. A positive electrode 1 is used also as a positive electrode case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alkaline battery, and more particularly to an alkaline battery which suppresses hydrogen gas generation inside the battery and prevents performance deterioration even when mercury or lead is not added.

[0002]

2. Description of the Related Art Alkaline batteries having zinc as a negative electrode acting substance include various batteries having manganese dioxide, silver oxide or oxygen in the air as a positive electrode acting substance depending on the application. There is.

In recent years, the demand for alkaline batteries has been expanding as a power source and memory backup due to the development of small electronic devices and cordless devices. However, in consideration of environmental problems, environmental pollutants such as mercury and lead are not used. Pollution is in progress.

[0004]

Conventionally, when mercury is used in an alkaline battery, the mercury covers the surface of the zinc powder or the negative electrode current collector to increase the hydrogen overvoltage on the surface and suppress the generation of hydrogen gas. Was there. However, if mercury is eliminated to make it pollution-free, naturally, the generation of hydrogen gas from the zinc powder and the negative electrode current collector increases, and problems such as swelling and leakage of the battery and performance deterioration during storage occur, These measures have become necessary.

Therefore, in order to suppress the generation of hydrogen gas from the zinc powder, a corrosion resistant alloy to which elements such as indium and bismuth are added, or a corrosion inhibitor is added to gel zinc. Although the gas generation from the zinc powder has been considerably suppressed by these suppression measures, the gas generation from the negative electrode current collector has become a more serious problem. Particularly in button type alkaline batteries, it is necessary to further suppress gas generation due to its structure, and since the area of the negative electrode current collector is larger than that of gel-like zinc, suppression of gas generation from the negative electrode current collector is essential. Become.
In order to suppress the generation of gas from the current collector, it has been conventionally proposed that the current collector be made of a zinc alloy having the same composition as zinc powder or be covered with indium or gallium, but sufficient effects can be obtained. I can't say that.

The present invention has been made to solve such a problem, and its purpose is to suppress generation of hydrogen gas inside the battery and prevent performance deterioration even when mercury is not added. To provide.

[0007]

In order to achieve the above object, the inventors of the present invention, after plating the negative electrode current collector with indium, heat-treat it in an inert gas atmosphere or in a vacuum to The inventors have found that hydrogen gas generation can be suppressed and have completed the present invention.

That is, the silver-free alkaline battery of the present invention is obtained by subjecting at least the surface of the negative electrode current collector, which comes into contact with the zinc gel, to indium plating and then heat-treating it in an inert gas atmosphere or in a vacuum. Characterize.

It is also effective to add an indium compound as a corrosion inhibitor to the negative electrode in order to further suppress the generation of hydrogen gas inside the battery. The mutual effect of the indium plating and the indium compound is effective for the battery. Internal resistance is reduced, and discharge performance is also improved. As the indium compound, any of indium hydroxide, indium oxide, indium chloride and the like may be used.

[0010]

Function The first cause of gas generation from the negative electrode current collector is that the hydrogen overvoltage of the material copper or brass itself is not sufficiently high, but processing stress remains when processing the negative electrode current collector. It often occurs from places with rough surfaces.

Since indium and gallium have a higher hydrogen overvoltage than copper and brass, if the surface is covered, gas generation is suppressed to some extent. However, this alone cannot remove the processing stress of the negative electrode current collector, and it cannot be said that gas generation is sufficiently suppressed. Therefore, by heating after indium plating as in the present invention, the processing stress can be removed and the surface becomes smooth, so that hydrogen gas generation can be suppressed. Further, gallium is not practical because the effect is not sustained because it dissolves in an alkaline solution.

[0012]

EXAMPLES Examples of the present invention and comparative examples will be described in detail below. (Example 1) A copper surface of a nickel-stainless-copper three-layer clad material was plated with indium, and this was applied to a negative electrode case 7 also serving as a negative electrode current collector for an LR44 type alkaline manganese battery as shown in FIG. Molded. This negative electrode case 7 was heat-treated at 150 ° C. for 2 hours in an inert gas atmosphere. Using this, an LR44 type alkaline manganese battery as shown in FIG. 1 was prepared. That is, in FIG. 1, reference numeral 1 denotes a positive electrode case which also serves as a positive electrode terminal. In this case, a positive electrode mixture 2 in which manganese dioxide powder and carbon powder are mixed, a separator 3 and a liquid holding material 4 are stacked in this order and housed, Further, a gel zinc 5 is put thereon, the negative electrode case 7 is fitted into the positive electrode case opening through the gasket 6, and the peripheral portion of the positive electrode case 1 is caulked inward. The gelled zinc negative electrode is composed of bismuth, indium,
40w using a smoothed zinc alloy with aluminum added
Gelled with polyacrylic acid in a t% aqueous solution of potassium hydroxide.

Example 2 An LR44 type alkaline manganese battery similar to Example 1 was prepared except that 500 ppm of indium hydroxide was added to the zinc alloy powder in the gel zinc negative electrode.

Example 3 An LR44 type alkaline manganese battery similar to Example 1 was prepared except that 500 ppm of indium oxide was added to the zinc alloy powder in the gel zinc negative electrode.

(Comparative Example 1) An LR44 type alkaline manganese battery similar to that of Example 1 was prepared, except that the negative electrode case serving also as the negative electrode current collector was not subjected to heat treatment.

(Comparative Example 2) An LR44 type alkaline manganese battery similar to that of Example 2 was prepared, except that the negative electrode case serving also as the negative electrode current collector was not subjected to heat treatment.

Comparative Example 3 An LR44 type alkaline manganese battery similar to that of Example 1 was prepared, except that the negative electrode case which also serves as the negative electrode current collector was not subjected to indium plating and heat treatment.

(Comparative Example 4) An LR44 type alkaline manganese battery similar to that of Example 2 was prepared, except that the negative electrode case serving also as the negative electrode current collector was not subjected to indium plating and heat treatment.

(Comparative Example 5) An LR44 type alkaline manganese battery similar to Comparative Example 3 was prepared except that lead was added to the zinc alloy powder of the gelled zinc negative electrode and zinc alloy powder having a conversion ratio of 3% was used. did.

The batteries of the examples and comparative examples prepared as described above were stored at 60 ° C., and changes in the total height of the batteries during storage and deterioration of the open circuit voltage were measured. These changes correlate with the hydrogen gas generation amount inside the battery, and the smaller the change amount, the smaller the hydrogen gas generation amount.

Further, in order to investigate the improvement of the discharge performance by adding the indium compound, 6.8 KΩ continuous discharge was conducted,
The discharge duration up to 1.2 V was investigated. Table 1 shows the results of these tests. All test results are average values of 20 pieces.

[0022]

[Table 1]

As is clear from Table 1, the battery produced according to the present invention suppresses hydrogen gas generation inside the battery even when mercury is not added, and leakage of liquid during storage and swelling of the battery occur. Performance deterioration is prevented. Further, by adding the indium compound to the negative electrode, the generation of hydrogen gas can be further suppressed and the discharge performance can be improved.

Although the button type alkaline manganese battery has been described in the above embodiment, the present invention is not limited to this, and a gelled zinc negative electrode such as a cylindrical alkaline dry battery, a silver oxide battery or an air zinc battery is used as a negative electrode. Of course, it can be applied to various alkaline batteries.

[0025]

As described above, according to the present invention,
Generation of hydrogen gas inside the battery is suppressed, and liquid leakage during storage, swelling of the battery, and performance deterioration are prevented. In addition, by adding the indium compound to the negative electrode, generation of hydrogen gas is further suppressed and discharge performance is improved, which is an excellent effect.

[Brief description of drawings]

FIG. 1 is a sectional view of an LR44 type alkaline manganese battery according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Positive electrode case, 2 ... Positive electrode mixture, 3 ... Separator, 4 ...
Liquid holding material, 5 ... Gel zinc, 6 ... Gasket, 7 ... Negative electrode case.

Claims (2)

[Claims] 1. In a silver-free alkaline battery using gel zinc as a negative electrode, the negative electrode current collector is subjected to indium plating on at least the surface portion in contact with gel zinc, and then in an inert gas atmosphere or in a vacuum. An alkaline battery characterized by being heat-treated. 2. The alkaline battery according to claim 1, wherein an indium compound is added to the gel zinc.