JPS6156286A - Alkali battery - Google Patents

Abstract

PURPOSE:To provide a titled battery which prevents pitting and extends the life thereof by polishing the copper or copper alloy layer on the suface of a negative current collector with a chemical polishing agent consisting of hydrogen peroxide and org. acid or the salt thereof and forming a film contg. benzotriazole or the driv. thereof thereon. CONSTITUTION:This alkali battery is provided with the negative current collector of which the copper layer or copper alloy layer on the surface is polished with the chemical polishing agent consisting of >=1 kinds of the hydrogen peroxide and org. acid as well as the org. acid salt and the film contg. at least the benzotriazole and the deriv. thereof is formed thereon. The oxide, oil, fine fragments of metals, etc. sticking to the copper layer on the surface are removed, by which the generation of gaseous hydrogen, the rupture of the vessel and the liquid leakage by pitting are prevented. The concn. of the above-mentioned hydrogen peroxide is preferably about 0.2-1.0mol/l. Formic acid, oxalic acid, acetic acid, citric acid, gluconic acid, etc. are used for the org. acid and the film is constitued of the benzotriazole and the deriv. thereof and amphoteric surface active agent.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an alkaline battery, and particularly 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). , the copper or copper alloy side is drawn so that it is on the inside of the container. The surface of the copper layer or copper alloy layer of the negative electrode container formed by such drawing processing, etc., is exposed to the production of copper oxide and lubrication during processes such as manufacturing the clad plate, slitting, punching and drawing. Oil stains and dirt may adhere. In addition, minute pieces of metal such as stainless steel and nickel also adhere.

Incidentally, alkaline degreasing and cleaning have conventionally been performed before battery assembly. However, if fine particles of stainless steel, nickel, etc. adhere to the copper layer or copper alloy layer of the negative electrode container, or if the particles are pressed after adhesion, alkaline degreasing cannot completely remove these fine particles, and battery assembly is difficult. This will later become a factor in the generation of hydrogen gas.

That is, the surface of the copper layer or copper alloy of the negative electrode container is amalgamated and galvanized by contacting the frozen zinc of the negative electrode active material due to the presence of the alkaline electrolyte. For this reason, even though the copper layer or copper alloy layer is a more noble metal than zinc,
Even when hydrogen comes into contact with zinc, the generation of gas is suppressed. However, stainless steel on the surface of the copper layer or copper alloy layer.

When fine pieces of nickel or the like adhere, the metal has a small hydrogen overvoltage, so when the negative electrode container is filled with an alkaline electrolyte and zinc, hydrogen gas is generated. In addition, in the case of copper oxide, oil, etc., if it comes into contact with frozen zinc in the presence of an alkaline electrolyte, it will take time for the copper layer or copper alloy layer to freeze and galvanize. It takes. 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 immediately sealed, so hydrogen gas continues to be generated within the sealed battery. When such hydrogen gas is generated, the inside of the battery is filled with hydrogen gas, increasing the internal pressure and causing rupture or leakage.

For this reason, recently, negative electrode containers have been used in which the surface copper layer or copper alloy layer is polished with a chemical polishing solution consisting of hydrogen peroxide and sulfuric acid before battery assembly. however,
Such chemically polished negative electrode containers have the following drawbacks.

(1) The chemical polishing liquid has a concentration of hydrogen peroxide of about 2 to 6.
mob/l, sulfuric acid concentration is approximately 0.1 to 2.0 mob
It is a highly corrosive solution with a high concentration of /1.

Therefore, the polishing speed is 0.1 to 0.5P/d-min.
Since this is relatively fast, localized pitting corrosion is likely to occur. In particular, the surface of the copper layer or copper alloy layer near the folded or folded portions of the drawn negative electrode container is not rough due to the processing and is thinner before processing, so the holes may Eclipses are likely to occur. The occurrence of such pitting corrosion causes liquid leakage. Additionally, if pitting corrosion reaches the stainless steel layer of a two-layer or three-layer clad plate, it may cause gas generation.

(2) Since the chemical polishing liquid is highly acidic (about pH 1 or less), an oxide film is formed even if a small amount of the chemical polishing liquid remains on the surface of the copper layer or copper alloy layer.

The formation of such an oxide film does not cause the generation of hydrogen gas.
This may cause rupture or leakage.

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

[Purpose of the invention]

The present invention aims to provide a long-life alkaline battery that does not suffer from pitting corrosion, is equipped with a cleaned negative electrode current collector, and is prevented from bursting or leaking.

[Summary of the invention]

The present invention involves polishing a surface copper layer or copper alloy layer with a chemical polishing liquid consisting of hydrogen peroxide and one or more selected from organic acids and organic acid salts to form a coating containing at least benzotriazole or its derivatives. The device is characterized by being equipped with a negative electrode current collector consisting of: According to this invention,
It is possible to obtain an alkaline battery equipped with a negative electrode current collector having a copper layer or a copper alloy layer on its surface that is cleaned without causing pitting corrosion and whose clean state is maintained with a coating of benzotriazole or the like. As a result, a long-life alkaline battery that prevents hydrogen gas generation and container rupture due to oxides, oil, and fine metal particles adhering to the surface copper layer or copper alloy layer, and prevents leakage due to pitting corrosion, etc. can be provided.

Examples of the organic acids constituting the chemical polishing liquid include formic acid, oxalic acid, acetic acid, citric acid, and gluconic acid. Furthermore, examples of the organic acid salts include sodium formate, potassium formate, sodium shelate, potassium shelate, and the like.

The concentration of hydrogen peroxide constituting the above chemical polishing liquid is 0.2~
A range of 1.0 mol/l is desirable.

The reason for this is that if the concentration is less than 0.2 mol/1, the reaction rate is slow and impurities on the surface of the copper layer or copper alloy layer cannot be sufficiently removed. On the other hand, the concentration is 1
．． If it exceeds 0 mol/73, the reaction rate will be too fast and there is a risk that pitting corrosion etc. will occur locally in the thin copper layer or copper alloy layer.

It is desirable that the chemical polishing liquid has a pH in the range of 3.0 to 5.0 within the hydrogen peroxide concentration range.

The reason for this is that if the pH is less than 3.0, pitting corrosion may occur), and if water washing is not done sufficiently,
An oxide film that causes hydrogen gas generation is likely to be formed on the surface of the copper layer or copper alloy layer. On the other hand, the pH of the polishing liquid is 5.
If it exceeds 0, the polishing speed will drop sharply, the impurity removal effect will be reduced, and there is a risk that the gas generation prevention effect and liquid leakage prevention effect will not be sufficiently achieved. Furthermore, the stability of hydrogen peroxide is reduced and self-decomposition is likely to occur, resulting in deterioration of workability.

The coating containing the benzo) IJ azole or its derivatives protects the surface of the cleaned copper layer or copper alloy layer,
It maintains its clean state and exhibits rust prevention effects.

Examples of such benzotriazole derivatives include methylbenzotriazole, benzothiazole, ethylbenzotriazole, and 2-mercazotopenzotriazole. Formation of such a film on a copper layer or copper alloy layer is usually carried out by immersion in a solution dissolved in a solvent such as water or alcohol, or by coating the solution. In this case, the concentration of benzotriazole etc. is 0.01 to 1.0% by weight, preferably 0.02% by weight.
It is desirable that the content be in the range of ~0.1% by weight.

Note that a film may be formed by adding an amphoteric surfactant to the polished copper layer or copper alloy layer together with benzotriazole or its derivative.

By adding such an amphoteric surfactant, a very thin adsorption film of several 10X to several 100X is formed on the copper layer or copper alloy layer, improving the wettability and forming an oxide film on the copper layer or copper alloy layer. Prevent generation. Furthermore, the amount of benzotriazole or its derivatives adsorbed onto the copper layer or copper alloy layer can be promoted, and a highly adsorbent anticorrosive film 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 serves as a physical barrier against pitting reactions of copper and zinc. As such amphoteric surfactants, those containing an amino group or an amino residue and a carboxyl group simultaneously in the molecule are particularly desirable.

Specifically, compounds represented by the following formulas (1) to (4),
Also included are hagelicin, alanine, panin, serine and the like.

R1-(NH・(CH2)-) nC00M...
・(3)\CH2□ ... (4) [However, R1 in the formula is an alkyl group having 8 to 14 carbon atoms, m,
n is an integer of 1 or 2, M is an alkali metal, R2 is a hydrogen atom, n) IJum, or CH2C00M group, X is a C00M group, CH2C00M group, or HCH(OH)CH2
- Indicates SO, M 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.
It is preferably in the range of 0.01 to 0.5% by weight, particularly 0.1 to 0.2% by weight.

[Embodiments of the invention]

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

Example 1 First, a three-layer clad plate with a thickness of 0.3 ILL consisting of a nickel layer 1, a stainless steel layer 2, and a copper layer 3 (thickness 30 μm) was drawn and processed to form a negative electrode for a butane-type alkaline battery as shown in FIG. Container 4 was produced. Subsequently, this negative electrode container was mixed with oxalic acid 4P/11. Sodium oxalate 151/1.35%
Hydrogen peroxide 80P/l, pH 3.5 chemical polishing liquid (
Polishing was performed for 4 minutes at a liquid temperature of 50°C. Next, the polished negative electrode container was immersed in an aqueous solution containing 0.05% by weight of benzotriazole at 80° C. for 30 seconds to form a benzotriazole film on the surface of the copper layer.

Using this polishing treatment and the negative electrode container on which the benzotriazole film was formed, the silver oxide battery 5R54 (
(outer diameter 11.6 m, height 3.05 m) was assembled. That is,
In FIG. 2, 5 is a positive electrode container made of a nickel-plated steel plate, and 6 is a positive electrode mixture made by adding graphite as a conductive agent to a silver oxide active material filled in the positive electrode container 5. 7
8 is an electrolyte holding material made of a porous fibrous material impregnated with an alkaline electrolyte, and 9 is frozen zinc as a negative electrode active material. 10 insulates between the positive electrode container 5 and the negative electrode container 4,
The opening of the positive electrode container 5 is curved inward and sealed with an insulating backing that seals the gap.

Example 2 After polishing the negative electrode container 4 shown in FIG. 1 in the same manner as in Example 1, an aqueous solution (liquid temperature A silver oxide battery having the same structure as shown in FIG. 2 was assembled, except that a composite film was formed on the copper layer by immersing the battery at 80° C. for 30 seconds.

Comparative Example The negative electrode container 4 shown in FIG. 1 was heated with hydrogen peroxide 4. mot/13
゜Sulfuric acid 0.42 moL/It chemical polishing liquid (solution temperature 5
A silver oxide battery having the same structure as shown in FIG. 2 was assembled, except that the battery was polished for 1 minute at 0°C.

For 100 batteries of Examples 1 and 2 and Comparative Example, the number of leaking batteries after being stored in a test tank at a temperature of 60°C and a humidity of 90% was measured using a 10x microscope, and the results are shown in the table below. The following results were obtained. Furthermore, the number of hydrogen gas generated was investigated after storing 100 batteries of Examples 1 and 2 and Comparative Example in a test chamber at similar temperature and humidity for 3 months. The results are also listed in the same table. In this test, a battery in which the stain pond height changed by 0.5n 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) equipped with a negative electrode container polished with a hydrogen peroxide-sulfuric acid-based chemical polishing solution had zero leakage when stored for 20 days, but after 40 days. When stored, the number of leaking items increases rapidly. On the other hand, the battery of the present invention (Example 1) equipped with a negative electrode container polished with a hydrogen peroxide-organic acid based chemical polishing liquid and further formed with a benzotriazole film, had a small number of defects after being stored for 40 days. Although leakage is observed, the number of batteries leaking does not increase as the number of days increases, unlike in the comparative example. On the other hand, in the battery (Example 2) equipped with a negative electrode container in which a composite film of benzotriazole and amphoteric surfactant was formed after polishing, the number of leaking batteries was further reduced compared to Example 1. . Also,
Regarding gas generation defects, the batteries of the present invention had only 1 in Example 1 and 0 in Example 2, which shows that the defective rate can be significantly improved compared to the comparative example.

Although the present invention is shown in the above embodiment, it is not limited to the tan-type alkaline battery, but can be similarly applied to the cylindrical alkaline battery shown in FIG. That is, 11 in FIG. 3 is a positive electrode container which also serves as a positive electrode terminal, and a positive electrode mixture 12 is filled under pressure in this container 11. The inside of this positive electrode mixture 12 is filled with frozen zinc 14 as a negative electrode active material via a seven-layer plate 13 made of nonwoven fabric. An insulating backing 15 made of synthetic resin is inserted into the opening of the positive electrode container 11, and by bending the upper part of the container 11 inward, the backing 15 is tightened and tightly attached. A sealing plate 16, which also serves as a negative electrode terminal, is attached to the backing 15. A sealing plate 16, which also serves as a negative electrode terminal, is attached to the lower surface of the sealing plate 16. A negative electrode current collector 17 made of brass is attached. By polishing the negative electrode current collector 17 of such a cylindrical alkaline battery with a chemical polishing solution having the same composition as in the example and further forming a film of benzotriazole or its derivative, pitting corrosion can occur on its surface. Since the impurities that cause gas generation can be removed for the same reasons as mentioned above, the adhesion with the insulating backing 15 is good, and rupture and leakage can be reliably reduced. I can do it.

〔Effect of the invention〕

As detailed above, according to the present invention, pitting corrosion does not occur,
It is possible to provide a long-life alkaline battery that is equipped with a cleaned negative electrode current collector and is prevented from bursting or leaking.

[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 tan-type alkaline battery obtained by the same example, and FIG. FIG. 2 is a longitudinal cross-sectional view showing a cylindrical alkaline battery according to an embodiment of the present invention. 1...Nickel layer, 2...Stainless steel layer, 3...
Copper layer, 4... Negative electrode container, 5, 11... Positive electrode container, 6
゜12...Positive electrode mixture, 7.13...Separator, 9
゜14... Zinc oxide, 10.15... Insulating quartz, 17... Negative electrode current collector. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (4)

[Claims] (1) Polishing the copper layer or copper alloy layer on the surface with a chemical polishing liquid consisting of hydrogen peroxide and one or more selected from organic acids and organic acid salts to form a coating containing at least benzotriazole or its derivatives. An alkaline battery characterized by comprising a negative electrode current collector. (2) The alkaline battery according to claim 1, wherein the organic acid is formic acid, oxalic acid, acetic acid, citric acid, or gluconic acid. (3) The alkaline battery according to claim 1, wherein the chemical polishing liquid has a pH of 3.0 to 5.0. (4) The alkaline battery according to claim 1, wherein the coating comprises benzotriazole or a derivative thereof and an amphoteric surfactant.