JPS6348394B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing an alkaline battery using an alkaline electrolyte, using iron oxide, manganese dioxide, etc. as a positive electrode active material, zinc, etc. as a negative electrode active material, and using an alkaline electrolyte. In general, in an alkaline battery, a positive electrode active material is filled in a metal positive electrode container that also serves as a positive electrode terminal, and a negative electrode active material and an alkaline electrolyte are filled in a metal negative electrode container that also serves as a negative electrode terminal, and then a separator is interposed. The two containers are fitted together via an insulating gasket consisting of an insulating gasket, and the opening of the positive electrode container is curved inward to form a hermetically sealed opening. For example, in the case of a button-type silver oxide battery, the negative electrode container is generally a two-layer clad plate of stainless steel and copper or a copper alloy, or a three-layer clad plate of nickel stainless steel, copper or copper alloy, with the copper or copper alloy side facing the container. It is manufactured by drawing so that it has the inner surface. The copper or copper alloy surface of the negative electrode container manufactured in this way is subjected to the production of cladding plates, slitting, punching, drawing, etc. processes such as the formation of oxides, the adhesion of dirt and dust, or the presence of metals such as stainless steel and nickel. The adhesion of fine particles cannot be avoided. Before battery assembly, pretreatment such as degreasing and cleaning is performed, but if these foreign substances get into scratches on the copper or copper alloy surface, or if they are pressed after adhesion, it is impossible to completely remove them with normal cleaning or other means. It is difficult to remove. Due to the presence of an alkaline electrolyte, the copper or copper alloy surface of the negative electrode container comes into contact with the negative electrode active material, ie, zinc chloride, to undergo amalgamation and galvanization.
Therefore, even though copper or copper alloy is more noble than zinc, hydrogen gas generation is suppressed even when it comes into contact with zinc, so the battery can be sealed. However, if foreign substances such as stainless steel or nickel remain on the copper or copper alloy surface, these foreign substances will remain exposed as they are difficult to be washed with water and galvanized. Since these metals have a small hydrogen overvoltage, they generate hydrogen gas when the negative electrode container is filled with an alkaline solution and zinc. Therefore, after assembly, hydrogen gas fills inside the battery, increasing the internal pressure of the battery, causing leakage, or causing the battery to burst. Structures that tend to generate hydrogen gas cannot be used as batteries. This is a serious flaw. This invention was made based on the above circumstances, and after polishing and cleaning the surface of copper or copper alloy in contact with the negative electrode active material of the negative electrode current collector with hydrogen peroxide and sulfuric acid-based chemical polishing liquid, mercury ions are removed. By treating with a rust preventive solution of copper or copper alloy containing copper and performing amalgamation and rust prevention treatment at the same time, the generation of hydrogen gas is reduced, so there is no leakage, impedance increase, rupture, etc., and the service life is extended. The present invention aims to provide a method for manufacturing alkaline batteries that can last for a long time and improve work efficiency. In other words, since it is difficult to remove foreign substances such as minute pieces of metal attached to the copper or copper alloy of the negative electrode container by normal cleaning methods, these harmful foreign substances are scraped off to a certain thickness on the surface of the copper or copper alloy. The problem was solved by this. The thickness to be removed by this polishing is determined by the degree of dirt and foreign matter adhering to the surface and the thickness of the copper or copper alloy. The standard thickness of the copper or copper alloy surface is about 10% of the total thickness of the clad plate, so if the clad plate is thin, the copper or copper alloy layer will also be thinner, which limits the thickness to be scraped. be done. If the thickness of the clad plate is 0.3mm, the thickness of the copper or copper alloy is generally around 30μ, and there is no risk of exposing the inner stainless steel layer even if it is removed by about 10μ, but it can be removed. This is expensive and impractical. It has been confirmed that the depth at which foreign matter such as stainless steel or nickel adheres to or is implanted into the copper or copper alloy surface of the negative electrode container is approximately 3 to 5 microns at most, and that it is possible to scrape it off by approximately 6 microns. Ta. In this case, chemical polishing is suitable as a means for scraping the copper or copper alloy surface, since the thickness of the scraping can be controlled relatively easily. More specifically, the use of hydrogen peroxide and sulfuric acid-based chemical abrasives has the advantage that the thickness to be scraped can be precisely controlled by selecting the composition of hydrogen peroxide and sulfuric acid, treatment temperature, and time. The reason why hydrogen peroxide and sulfuric acid based chemical abrasives are used as the specified chemical polishing liquid in this invention is that chemical polishing liquids in which hydrogen peroxide is mixed with nitric acid or hydrochloric acid generate a large amount of nitrous acid or chlorine gas.
This is because this invention has the advantage of being able to reduce gas generation. If the copper or copper alloy surface is left untouched after foreign matter has been removed, it will oxidize, so if it comes into contact with zinc chloride in the presence of a small amount of alkaline electrolyte contained in the battery, oxidation and galvanization will not occur. It takes time for the copper or copper alloy surface to generate hydrogen gas. Since the battery is assembled immediately after filling the negative electrode container with zinc chloride and alkaline electrolyte, hydrogen gas generation continues until after the battery is assembled. When hydrogen gas is generated inside the battery, it increases its impedance or causes leakage due to an increase in internal pressure. Therefore, in the present invention, after cleaning by chemical polishing, this clean surface is immersed in a rust preventive solution of copper or copper alloy containing mercury ions to perform amalgamation and rust prevention treatment at the same time. Generation of hydrogen gas is prevented by filling with zinc and alkaline electrolyte. In this case, triazole derivatives commonly used as rust preventive agents for copper or copper alloys can be used as the rust preventive agent. In addition, the negative electrode container is generally formed into a shape with a folded part around the periphery by drawing processing, and when forming this folded part, the copper or copper alloy in the vicinity of the folded part is highly processed, so it is not necessary to stretch it. It has been made thinner than other parts. Therefore, if this part is scraped off with a chemical polishing solution, the stainless steel will be exposed, which may generate hydrogen gas. However, in this invention, since chemical polishing is performed while avoiding the folded portion, consideration is given to prevention of hydrogen gas generation in this respect as well. Next, an embodiment of the present invention will be described with reference to the drawings. As shown in Figure 1, a three-layer clad plate made of nickel 1, stainless steel 2, and copper 3 with a total thickness of 0.3 mm and a copper thickness of 30 μm is used, and this is drawn to form a negative electrode container. Produce 4. After a jig 6 made of synthetic resin is brought into contact with the peripheral folded portion 5 of this negative electrode container 4 to cover the surface, it contains about 10 moles of hydrogen peroxide and about 0.45 moles of sulfuric acid, and the molar ratio of sulfuric acid to hydrogen peroxide is 0.045. After processing with a chemical polishing solution for about 2 minutes at room temperature, the exposed surface of the copper 3 is chemically scraped by repeating washing with water, washing with sulfuric acid, washing with water, neutralization, and washing with water to remove foreign substances and clean it. do. Immediately immerse this clean surface in an aqueous solution containing approximately 0.1 mg of mercury ion per negative electrode container and 0.2% benzotriazole as a rust preventive agent.
After processing at ℃ for about 15 seconds to simultaneously form amalgam and form a rust-preventing film, the jig 6 was removed and washed with water and dried. The average thickness of the copper surface is approximately 6μ.
shall be. Using this negative electrode container 4, a silver oxide battery SR54 (outer diameter 11.6 mm, height 3.05 mm) as shown in FIG. 2 was assembled. In FIG. 2, 7 is a bottomed short cylindrical positive electrode container made of nickel-plated steel plate, 8 is an anode mixture formed by adding graphite as a conductive agent to a silver oxide active material, 9 is an ion-permeable separator, and 10 1 is an electrolyte holding material made of a porous fiber material impregnated with an alkaline electrolyte, and 11 is zinc chloride as a negative electrode active material. Reference numeral 12 denotes an insulating packing that insulates the gap between the positive electrode container 7 and the negative electrode container 4 and seals the gap therebetween, and the opening of the positive electrode container 1 is curved inward to fasten the packing. In the figure, 13 is a ring. For comparison with batteries (A) to (E) with various treatment solution compositions, including battery (C) made in this way, the same negative electrode container was washed with trichlene, alkaline, washed with water, and then dried. A comparison was made with respect to leakage with a conventional battery (F) assembled using a conventional battery. In other words, Table 1 is
These batteries were stored in a test tank at a temperature of 60°C and a humidity of 90%, and the number of leaked batteries was calculated using a 10x microscope.

[Table] In addition, Table 2 shows the changes in height due to hydrogen gas generation, etc. of batteries stored for 3 months at a temperature of 45°C and humidity of 90%.
This shows the number of batteries whose price has increased by more than mm.

【table】

[Table] According to Table 1, in the case of conventional product (F), the number of storage days
In contrast to batteries (A) to (E) according to the present invention, the leakage started after 20 days and rapidly increased as the number of days increased.
In the case of , a small number of leaks start after 30 days of storage, and even if the number of days increases, the number of leaks is significantly smaller than in the case of conventional product (F). Furthermore, according to Table 2, the number of defects can be suppressed to about 1/7 or less in the batteries (A) to (E) according to the present invention compared to the number of defects in the conventional product (F). In addition, through Tables 1 and 2, hydrogen peroxide 8
~10 mol, sulfuric acid 0.25-0.6 mol, molar ratio of sulfuric acid to hydrogen peroxide in the range 0.03-0.06
It can be seen that particularly good test results are obtained in cases (B) to (D). As described above, according to the present invention, after polishing and cleaning the surface of the copper or copper alloy in contact with the negative electrode active material of the negative electrode current collector with hydrogen peroxide and sulfuric acid-based chemical polishing liquid, the surface of the copper or copper alloy containing mercury ions is removed. By treating with a rust preventive solution of copper or copper alloy, and performing amalgamation and rust prevention treatment at the same time, hydrogen gas generation is reduced, so there is no leakage, impedance increase, rupture, etc., and the service life is extended. It is possible to provide a method for manufacturing an alkaline battery that can improve work efficiency. Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist. Although the above examples show the case where a triazole derivative is used as the rust preventive agent, the rust preventive agent is not limited to this. In addition to benzotriazole derivatives, hexamethyleneimine benzoate, cyclohexylamine dinitrobenzoate, and the like can be cited as rust preventive agents that chemically adsorb onto copper or copper alloys.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the manufacturing process of one embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing a silver oxide battery obtained by the same embodiment. 1...nickel, 2...stainless steel,
3... Copper, 4... Negative electrode container, 5... Peripheral folded part, 6... Jig, 7... Positive electrode container, 8... Anode mixture, 9... Separator, 10... Electrolyte holding material,
11...Zinc chloride, 12...Insulating packing, 1
3... Ring body.

Claims (1)

[Scope of Claims] 1. A pretreatment step of polishing and cleaning the surface of the copper or copper alloy 3 in contact with the negative electrode active material of the negative electrode current collector 1 with a hydrogen peroxide/sulfuric acid-based chemical polishing liquid; and the pretreatment step. Negative electrode current collector 1 is prepared by immersing the obtained negative electrode current collector in a solvent containing mercury ions and a copper or copper alloy rust preventive agent.
A method for producing an alkaline battery comprising a post-treatment step of simultaneously applying an amalgam coating and a rust preventive coating to the surface of the copper or copper alloy 3. 2. The method of manufacturing an alkaline battery according to claim 1, wherein the chemical polishing liquid contains 8 to 10 moles of hydrogen peroxide and 0.25 to 0.6 moles of sulfuric acid. 3. The method of manufacturing an alkaline battery according to claim 2, wherein the chemical polishing liquid has a molar ratio of sulfuric acid to hydrogen peroxide in a range of 0.03 to 0.06. 4. The method for manufacturing an alkaline battery according to any one of claims 1 to 3, characterized in that a triazole derivative is used as the rust preventive agent.