JPH07176306A - Alkaline dry battery - Google Patents

Abstract

PURPOSE:To provide an alkaline dry battery suppressing the hydrogen gas generated from a current collector and excellent in leak-resistant characteristic by using a zinc alloy added with no mercury for a negative electrode active material, and using copper or a copper alloy for a negative electrode current collector (referred to as a current collector hereafter). CONSTITUTION:A zinc alloy added with no mercury is used for the active material of a gelatinous zinc negative electrode 2, copper or a copper alloy is mainly used for a current collector 4 in this alkaline dry battery, Cu having high hydrogen overvoltage is applied on the surface of the current collector 4 at 0.10mum or above by electroless plating. The Fe, Cr, Co, Mo, W, and their oxides fixed or bitten on the surface of the current collector 4 are shielded, and the alkaline dry battery suppressing the generation of hydrogen gas and excellent in leak-resistant characteristic is obtained.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an alkaline dry battery,
Particularly, the present invention relates to an alkaline dry battery in which hydrogen gas generation is suppressed in a battery in which the negative electrode active material is a zinc alloy powder containing no mercury and the leakage resistance is improved.

[0002]

2. Description of the Related Art In alkaline dry batteries using zinc as a negative electrode active material, hydrogen gas is generated during storage of the battery due to the corrosion reaction of zinc, the internal pressure of the battery increases, and the electrolyte is pushed out to the outside to prevent leakage. Has the problem that
In some cases, there was a risk of the battery bursting.

As a countermeasure, zinc hydride powder to which mercury is added is used as a negative electrode active material for the purpose of increasing hydrogen overvoltage of zinc which is a negative electrode active material, preventing corrosion of zinc and suppressing generation of hydrogen gas inside the battery. Things have generally been done. Negative electrode current collector of this zinc negative electrode (hereinafter referred to as current collector)
Also, conventionally, a material such as copper or a copper alloy has been generally used, and the surface of the current collector has been selected by contact with a zinc hydride negative electrode. Further, in order to remove impurities such as Fe, Ni, Cr, Co, Mo, W or their oxides, which promotes corrosion of zinc, on the surface of the current collector, and suppress the generation of hydrogen gas, before the battery is assembled. A method of cleaning the surface of the current collector with an alkaline degreasing solution or polishing with a chemical polishing liquid such as acid or hydrogen peroxide, or a current collector in which a metal having a high hydrogen overvoltage is electrolytically plated is proposed.

However, even with the conventional methods of cleaning and chemically polishing the current collector or the current collector electrolytically plated with a metal having a high hydrogen overvoltage, the zinc alloy powder containing no mercury has excellent corrosion resistance, and It has not been possible to obtain an alkaline dry battery that reduces the variation in product quality and achieves a high level of stabilization. The reason will be described below.

[0005]

Generally, a current collector mainly composed of copper or a copper alloy such as brass is used as a current collector of an alkaline dry battery. In FIG.
In order to set 0 to a predetermined wire diameter, generally, one drawn by several steps of wire drawing manufacturing process as shown in FIG. 2 is used. Since these drawing dies 10 are usually made of super steel or hot work tool steel, fine particles of metal such as iron and nickel adhere to the surface of the current collector produced by the super fine steel or hot work tool steel. In many cases, the piece bites into the surface of the current collector and adheres to it.

Therefore, in the conventional method, the alkaline degreasing treatment of the current collector cannot completely remove the fine particles, which becomes a cause of generation of hydrogen gas after the battery is assembled.

Further, even when polishing with an acid or a chemical polishing material which is effective for the cleaning action, it is impossible to completely remove the fine particles which are deeply invaded and fixed on the surface of the negative electrode current collector.
It becomes a factor of generating hydrogen gas.

Further, in the case of current collectors electrolytically plated under various electrolytic conditions, Fe, Ni,
Cr, Mo, W or oxides of these which can be hidden, but which dig deeply Fe, Ni, Cr, Co, Mo, W or pins which cannot be plated on these oxides and are generated on the plating surface As in the above case, the generation of hydrogen gas is increased from the holes. The present invention solves the above-mentioned conventional problems. Even when a mercury-free zinc alloy powder is used in an alkaline dry battery, generation of hydrogen gas is suppressed, liquid leakage resistance is excellent, and variation in product quality is reduced. An object is to provide a stabilized alkaline dry battery.

[0009]

Means for Solving the Problems The inventors of the present invention have made earnest studies in accordance with this object. As a result, when a mercury-free zinc alloy powder was used in an alkaline dry battery, impurities adhered to the surface of the current collector, especially It has been found that fine particles such as Fe, Ni, Cr, Co, Mo, W or oxides thereof which can be easily fixed in the wire drawing manufacturing process of electric wires increase hydrogen generation. Moreover, it was found that the portion where hydrogen gas is continuously generated is a portion where impurities are unevenly distributed on the surface of the current collector. From these findings, it is possible to suppress the generation of hydrogen and improve the corrosion resistance by concealing the impurities sticking to the surface of the current collector by electroless plating of Cu having a high hydrogen overvoltage, and thus the present invention is reached. did.

[0010]

[Function] F on the surface of the current collector mainly composed of copper or copper alloy
When fine particles of e, Ni, Cr, Co, Mo, W or these oxides adhere, the fine particles have a small hydrogen overvoltage. Therefore, when this current collector is inserted into the zinc negative electrode of an alkaline dry battery, hydrogen Gas is generated.

Particularly, when a mercury-free zinc alloy powder is used as a negative electrode active material for an alkaline dry battery, hydrogen gas is remarkably generated as compared with the screened zinc alloy powder. Therefore, in the current collector, fine Fe, which is fixed and bites in the manufacturing process,
By electrolessly plating Ni, Co, Mo, W or these oxides with Cu having a high hydrogen overvoltage, it is possible to relatively uniformly plate the flaws or recesses of the current collector, which is the feature of the plating. It is possible to cover and adhere the fine impurities that have adhered and cut into the surface with Cu having a high hydrogen overvoltage.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An alkaline dry battery according to an embodiment of the present invention will be specifically described below with reference to the drawings.

A brass current collector wire 30 obtained in the manufacturing process shown in FIG. 2 was processed into a collector having a diameter of 1.5 mm and a length of 30 mm, and a copper sulfate, sodium potassium tartrate, sodium hydroxide, formaldehyde, Electroless Cu plating with a plating solution made from thiourea, plating thickness 0.05μ
m, 0.10 μm. 0.15 μm, 0.20 μm. Prepared.

The current collector thus obtained was used for the alkaline manganese dry battery LR6 type shown in FIG.
It was set to 3 and 4. In FIG. 1, 1 is a positive electrode mixture prepared by adding manganese dioxide to which graphite is added as a conductive material, and 2 is a gelling agent in an alkaline electrolyte solution in which potassium hydroxide is dissolved, and a zinc alloy powder containing no mercury dispersed therein. It is a gelled zinc negative electrode. 3 is a separator interposed between the positive electrode mixture 1 and the gel zinc negative electrode 2, 4 is a negative electrode current collector, 5 is a positive electrode terminal cap, 6 is a metal case, 7 is a battery outer can, 8 is a sealing gasket, 9 Is a bottom plate forming a negative electrode terminal.

As a comparative example, an alkaline dry battery LR6 type was assembled using the following two types of negative electrode current collectors 4 in the same manner as in the example.

Comparative example A is a brass current collector chemically polished with a mixed solution of hydrogen peroxide and sulfuric acid, and comparative example B is a brass current collector rod plated with Cu (5 μm) by an electrolytic method.

In this way, the present embodiment 1, 2, 3, 4
Table 1 shows the results of the number of leaked liquids (visual judgment) after the 10,000 batteries each of Comparative Examples A and B were stored at room temperature for 3 months.

[0018]

[Table 1]

From the results shown in Table 1, this example shows that the current collector 4
The electroless plating with the plating thickness of 0.1 μm or more does not leak at all, and practical leakproof characteristics can be secured. However, liquid leakage occurred at 0.05 μm. Also,
The leaked battery generated a large amount of gas, and Fe, Ni, Cr, etc. were detected on the surface of the current collector 4. This is 0.
Fe, Ni, C that penetrate into the surface when the thickness is less than 05 μm
It is considered that fine pieces such as r cannot be completely covered with Cu of electroless plating. On the other hand, in Comparative Examples A and B, many liquid leaks were generated, and Fe, Fe,
Cr, Ni, etc. were detected. It is considered that the reason for this is that, in the chemical polishing of Comparative Example A, fine impurities that adhere to the surface can be removed, but those that have deeply penetrated into the surface could not be dissolved and removed. Further, the brass base material of Comparative Example B plated with electrolytic Cu is different from the electroless plating in that Fe, Cr, and N are present in the recesses.
It is considered that i and the like could not be hidden by Cu.

[0020]

As is apparent from the above description of the embodiments, according to the alkaline dry battery of the present invention, even if the mercury-free zinc alloy powder is used as the negative electrode active material of the alkaline dry battery,
It is possible to provide a good quality product that suppresses the generation of hydrogen gas and has excellent leakage resistance.

[Brief description of drawings]

FIG. 1 shows an alkaline dry battery (LR6) according to an embodiment of the present invention.
Type) vertical sectional view

FIG. 2 is a drawing showing an enlarged cross-section of a main part of a wire drawing manufacturing process of a wire material for a negative electrode current collector used in an embodiment of the present invention and a conventional alkaline dry battery.

[Explanation of symbols]

 1 Positive Electrode Mixture 2 Gel Zinc Negative Electrode 3 Separator 4 Negative Electrode Current Collector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kohei Kitagawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Keisuke Tanaka, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A negative electrode in which a mercury-free zinc alloy powder is mixed and dispersed in a gelled alkaline electrolyte as a negative electrode active material provided in the center of a battery, and a positive electrode provided on the outer periphery of the negative electrode via a separator. An alkaline dry battery comprising a negative electrode current collector mainly composed of copper or a copper alloy inserted as a current collector in the negative electrode, the alkali comprising a negative electrode current collector having electrolessly plated copper on its surface. Dry batteries. 2. The alkaline dry battery according to claim 1, which has a copper electroless plating thickness of 0.1 μm or more.