JPS61267265A - Alkaline battery - Google Patents

Abstract

PURPOSE:To obtain a alkaline battery of long life, by providing a negative electrode current collector whose copper or copper alloy surface layer is coated with a film containing a tetrazole compound, to suppress the generation of hydrogen gas to prevent a rupture and a liquid leak. CONSTITUTION:The surface of a copper or copper alloy layer is coated with a film containing tetrazole compound so that hydrogen gas is prevented from being generated due to an oxide, oil and a fine powder of metal clinging to the copper or copper alloy layer, to rupture a container, and a liquid leak is kept from occurring due to holing corrosion or the like. An alkaline battery of long life is thus provided. The film containing the tetrazole compound adheres to the surface of the copper or copper alloy layer to prevent rust. An example of the tetrazole compound is 5-amino-1H-tetrazole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] This invention relates to an alkaline battery with an improved negative electrode current collector.

[Technical background of the invention and its problems]

For example, in the case of a button-type silver oxide battery, a two-layer clad plate of stainless steel and copper or a copper alloy, or a three-layer clad plate of nickel, stainless steel, and copper or a copper alloy is generally used as the negative electrode current collector (negative electrode container). , which is drawn so that the copper or copper alloy side is on the inside of the container is used. The surface of the copper layer or copper alloy of the negative electrode container comes into contact with the frozen zinc of the negative electrode active material due to the presence of the alkaline electrolyte, and is amalgamated and galvanized. Therefore, even though the copper layer or copper alloy layer is a more dangerous metal than zinc, generation of hydrogen gas is suppressed even if the copper layer or copper alloy layer comes into contact with zinc. However, on the surface of the copper layer or copper alloy layer of the negative electrode container made by drawing, etc., copper oxides are formed, lubricating oil stains, etc. Dust, metal marks such as stainless steel and nickel (fine powder) adhere to them. Metals such as stainless steel and nickel have a small hydrogen overvoltage, so hydrogen gas is generated when the negative electrode container is filled with alkaline electrolyte and zinc. Also,
Copper oxide and oil on the surface of the negative electrode container.

When a film of dust or the like is formed, when the alkaline electrolyte comes into contact with frozen zinc, it takes a long time for the copper layer or copper alloy layer to freeze and become galvanized. Therefore, hydrogen gas is generated from the copper layer or copper alloy layer. During battery manufacturing, the negative electrode container is filled with frozen zinc and an alkaline electrolyte, and then the battery is immediately sealed, so the generation of hydrogen gas continues inside the sealed battery. When hydrogen gas is generated in this manner, the inside of the battery is filled with hydrogen gas, increasing the internal pressure and causing rupture or leakage.

For this reason, before battery assembly, the copper layer or copper alloy layer on the surface of the negative electrode current collector is subjected to alkaline degreasing treatment to remove oil, dirt, etc., and then pickling treatment to remove steel oxides. A new negative electrode container came into use. However,
Alkaline degreasing or pickling alone can damage the surface of the negative electrode container.
The attached low-fine powder cannot be completely removed, and hydrogen gas is generated after the battery is assembled.

The above-mentioned problem is not limited to button-type alkaline batteries, but also causes pitting corrosion in copper or copper alloy current collector rods used as negative electrode current collectors in cylindrical alkaline manganese batteries, which causes damage to the negative electrode current collector and insulating backing. This has the disadvantage that the electrolyte inside the battery tends to leak to the outside because it impairs the adhesion of the bonding surface with the battery.

Therefore, in order to solve these problems, the applicant has already proposed the following alkaline battery. That is, this alkaline battery is manufactured by polishing the copper layer or copper alloy layer on the surface of the negative electrode container or current collector with a chemical polishing solution consisting of hydrogen peroxide and sulfuric acid, and then treating the negative electrode container or current collector with a benzotriazole compound. It has a coating formed on it. This penzole compound has the advantage of being particularly adsorbent to the copper surface, protecting the surface of the copper layer or copper alloy layer, and exhibiting a rust-preventing effect. This protects the surface of the cleaned copper layer or copper alloy layer and prevents oxides from forming.

It was possible to prevent the generation of hydrogen gas caused by oil and fine metal powder, sulfur cracking of the container, and prevent liquid leakage due to pitting corrosion.

Furthermore, while conducting research, the applicant found that 5-amino-IH-tetrazole is superior to benzotriazole. The reasons why 5-amino-IH-tetrazole is superior to benzotriazole are that the coating has good alkali resistance, that it does not react with the zinc cathode it is in contact with, and that it has a corrosion-inhibiting effect on zinc, making it highly resistant to gases. Reasons include the low occurrence of this disease.

[Purpose of the invention]

The present invention was made in view of the above problems, and an object thereof is to provide a long-life alkaline battery that suppresses the generation of hydrogen gas after battery assembly and prevents bursting and leakage.

[Summary of the invention]

The present invention is characterized by comprising a negative electrode current collector formed by forming a coating containing a tetrazole compound on the surface copper layer or copper alloy layer.

The film containing the above-mentioned tetrazole compound adsorbs to the surface of the copper layer or copper alloy layer and exhibits a rust-preventing effect. Examples of such tetrazole compounds include 5-amino-IH
Examples include -tetrazole, IH-tetrazole, 1-methyltetrazole, and 2-methyltetrazole.

Formation of such a coating on a copper layer or copper alloy layer is usually carried out by dissolving it in a solvent such as water or alcohol and immersing it in the solution, or by coating the solution. In this case, the concentration of the tetrazole compound is 0.01 to 1.0% by weight
, more preferably in the range of 0.05 to 0.2% by weight.

Note that a coating may be formed by adding an amphoteric surfactant to the polished copper layer or copper alloy scraps together with a tetrazole compound. By adding such an amphoteric surfactant, a very thin adsorption film with a thickness of 5 to 10 OA per layer is formed on the copper layer or copper alloy layer, improving wettability, and an oxide film on the copper layer or copper alloy layer is formed. Prevent generation. Furthermore, the adsorption amount of the tetrazole-based compound to the copper layer or copper alloy layer can be promoted, and a highly adsorbent anticorrosive coating can be formed on these layers. Furthermore, it reinforces pitting corrosion in the copper layer or copper alloy layer and weak parts existing at grain boundaries, and acts as a physical barrier against pitting reactions of copper and zinc. As such amphoteric surfactants, those containing both an amino group or an amino residue and a carboxyl group in the molecule are particularly desirable.

Specifically, compounds represented by the following formulas (1) to (4),
Alternatively, glycine, alanine, vanine, serine, etc. can be mentioned.

R, -(NH-(CH7)m)ncooM ・,, ・
,...--+31 hydrogen atoms, sodium, or CH
,,C00M group, L represents a C00M group, a CH2C00M group, or a CH(OH)CH2,S03M group. ] Among the above amphoteric surfactants, formula (1) is particularly preferred.

(2) Alkyl mono(or di)alanates are suitable. When such an amphoteric surfactant is dissolved in the above-mentioned water or alcohol solvent, the concentration should be 0.
A range of 0.01 to 0.5% by weight, particularly 0.1 to 0.2% by weight is preferred.

〔Effect of the invention〕

According to the present invention, by forming a film containing a tetrazole compound on the surface of the copper layer or copper alloy layer, hydrogen gas is generated by oxides, oil, and fine powder attached to the copper layer or copper alloy layer. Therefore, an alkaline battery with a long life can be obtained, which can prevent container rupture and leakage due to pitting corrosion, etc.

Furthermore, by adding an amphoteric surfactant together with a tetrazole compound, a thin adsorption film is formed on the copper layer or copper alloy layer, which improves wettability and prevents the formation of an oxide film. The system compounds can be adsorbed well, and a rust-preventive coating with high adsorption properties can be formed.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

Example 1 First, nickel layer 1. Stainless steel layer 2. A three-layer clad plate having a thickness of &0.3 vm consisting of copper layer 3 (thickness 30 μm) was drawn, degreased between the button shapes 7 shown in FIG. 1, and then washed with water. Next, 30% with 10% sulfuric acid solution.
After treating for seconds, the soot was washed again with water and further added 0.1% of 5-amino-IH-tetrazole as a tetrazole compound.
A film of 5-amino-IH-tetrazole was formed on the surface of the copper layer by immersing it in a 00% by weight aqueous solution (liquid temperature: 60° C.) for 30 seconds.

Using this polishing treatment and the negative electrode container on which the 5-amino-IH-tetrazole film was formed, the silver oxide battery 8R54 (outer diameter 11.6 wux, height 3.05 m) shown in FIG.
5) was assembled. That is, in FIG. 2, 5 is a positive electrode container made of a nickel-plated copper plate, and 6 is a positive electrode mixture made by adding graphite as a conductive agent to the silver oxide active material filled in the positive electrode container 5. Reference numeral 7 denotes an ion-permeable separator, and 8 denotes an electrolyte holding cell 9 made of a porous fibrous material impregnated with an alkaline electrolyte, which is frozen zinc as a negative electrode active material. Reference numeral 10 denotes an insulating backing that insulates between the positive electrode container 5 and the negative electrode container 4 and seals the gap therebetween, and the opening of the positive electrode container 5 is curved inward to seal it.

Example 2 After the negative electrode container 4 shown in FIG. 1 was subjected to alkali degreasing treatment and pickling treatment in the same manner as in Example, 0.10% by weight of 5-amino-IH-tetrazole and lauryl monoaneller (N) were added.
A silver oxide battery with the same structure as shown in Figure 2 was used, except that a composite film was formed on the copper layer by immersing it in an aqueous solution containing 0.2% by weight of a-salt (liquid temperature: 60°C) for 60 seconds. Assembled.

Comparative Example 1 A silver oxide battery was assembled with the same structure as shown in FIG. 2, except that the negative electrode container 4 shown in FIG. .

Comparative Example 2 Figure 1 (Same as shown in Figure 2 except that the negative electrode container 4 shown here was subjected to alkaline degreasing treatment in the same manner as in Example 1, and then a film was formed on the surface of the copper layer using benzotriazole. A silver oxide battery with the same structure was assembled.

Therefore, the batteries 10 of Examples 1 and 2 and Comparative Examples 1 and 2
After storage in a test tank at a temperature of 60° C. and a humidity of 90%, the number of leaking samples was measured using a microscope with a magnification of 10 times, and the results shown in the table below were obtained. Furthermore, 100 batteries of Examples 1 and 2 and Comparative Examples 1 and 2 were stored in a test chamber at the same temperature and humidity for 3 months, and then the number of hydrogen gas generated was investigated. The results are also listed in the same table. In this test, a battery in which the battery height changed by 0.5 am or more due to hydrogen gas generation was determined to be a hydrogen gas generating battery.

As is clear from the table above, the battery (Comparative Example 1) equipped with an alkali-degreased negative electrode container had two leaks when stored for 20 days, but the number of leaks suddenly increased after storage for 40 days. increases.

In addition, a battery equipped with a negative electrode container treated with alkaline degreasing and coated with benzotriazole (Comparative Example 2) shows some leakage after 40 days of storage, but as the number of storage days increases, the number of leaks rapidly increases. There is a tendency to increase.

On the other hand, it was subjected to alkaline degreasing treatment and further 5-amino-
The battery of the present invention (Example 1) equipped with a negative electrode container coated with IH-tetrazole showed some leakage after 40 days of storage, but no leakage occurred as in Comparative Example 1 even after storage for 40 days. There is no sudden increase in the number of batteries that drain, and the increase is gradual compared to Comparative Example 2.

On the other hand, in a battery (Example 2) equipped with a negative electrode container in which a composite film of 5-amino-IH-tetrazole and an amphoteric surfactant was formed after alkaline degreasing, the leakage rate was even greater than in Example 1. The number of drained batteries is reduced.

Regarding gas generation defects, the batteries of the present invention had only 1 battery in Example 1, 0 batteries in Example 2, and 1 battery in Comparative Example 1.
, 2ζ, it can be seen that the defective rate can be significantly improved.

Note that the present invention is not limited to the button-type alkaline battery shown in the above embodiment, but can be similarly applied to the cylindrical alkaline battery shown in FIG. That is, 11 in FIG. 3 is a positive electrode container that also serves as a positive electrode terminal, and the number inside this container 11 is the positive electrode mixture 12.
is filled under pressure.

A separator 13 made of non-woven fabric is placed inside this positive electrode mixture 12.
Zinc hydrate 14 as a negative electrode active material is filled through the tube. An insulating backing 15 made of synthetic resin is inserted into the opening of the positive electrode container 11, and the backing 15 is tightened and tightly attached by bending the upper part of the container 11 inward.

On this backing 15 is a sealing plate 16 which also serves as a negative electrode terminal.
Zinc hydrate 1 is attached to the lower surface of the sealing plate 16 through the backing 15 and the separator 13.
A negative electrode current collector 17 made of brass and extending into the inside of the housing 4 is attached. Negative electrode current collector 17 of such a cylindrical alkaline battery
was subjected to alkaline degreasing treatment in the same manner as in the example, followed by pickling treatment and further forming a film of 5-amino-IH-tetrazole to remove impurities that cause gas generation for the same reason as mentioned above. Moreover, the adhesion with the insulating backing 15 is improved, and the possibility of rupture and leakage is reliably reduced.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications within the scope of the invention without changing the gist.

[Brief explanation of drawings]

FIG. 1 is an enlarged cross-sectional view showing a negative electrode current collector in an example of the present invention, FIG. 2 is a longitudinal cross-sectional view showing a button-type alkaline battery obtained in Example t, and FIG. FIG. 7 is a longitudinal cross-sectional view showing a cylindrical alkaline battery showing another example.

Claims (2)

[Claims] (1) An alkaline battery comprising a negative electrode current collector formed by forming a coating containing a tetrazole compound on a copper layer or a copper alloy layer on the surface. (2) The alkaline battery according to claim 1, wherein the coating is composed of a tetrazole compound and an amphoteric surfactant.