JPS61218066A - Alkaline battery - Google Patents

Abstract

PURPOSE:To reduce production cost of current collector of alkaline battery and decrease the progress of alkaline electrolyte creepage caused by amalgamation by forming a slender iron rod in a desired shape, applying Fe-Ni alloy plating on the iron rod, and using it as a negative current collector. CONSTITUTION:A positive mix 2 comprising the mixture of positive active material, conductive material, and electrolyte is pressed against the inside of a positive can 1 comprising nickel plated iron plate. A gelled negative electrode 4 mainly comprising amalgamated zinc powder is accommodated into the hollow part of the positive mix 2 through a separator. A slender iron rod is formed so as to have a head 5a having larger diameter, a pip 5c, and a tapered edge 5b by a mold, then Fe-Ni alloy plating is applied on the surface to form a negative current collector 5. One end of the current collector is welded to a negative terminal plate 8, and the other end is inserted into the boss of a sealing gasket 6. The current collector is inserted into the gelled negative electrode 4, then a battery is assembled. The Fe-Ni alloy plating prevents the iron base material from rusting.

Description

[Detailed Description of the Invention] <Industrial Field of Application> The present invention relates to alkaline batteries, and more specifically, to cylindrical alkaline batteries that reduce costs and improve leakage resistance by improving the material of the negative electrode current collector. This invention relates to alkaline batteries such as hermetic button-type alkaline batteries.

<Prior art> In an alkaline battery using a negative electrode formed by dispersing frozen powdered zinc into a gel with a gelling agent such as carboxymethylcellulose and an alkaline electrolyte such as KOI-1 or Na01-1, the current collector of the negative electrode is In order to increase efficiency and improve battery discharge performance, a configuration is adopted in which a negative electrode current collector, one end of which is electrically connected to a negative electrode terminal plate by welding or the like, is embedded in a gelled negative electrode. Taking a cylindrical alkaline battery as an example, the negative electrode current collector is a long, slender rod-shaped one in which the end on the negative terminal plate side is processed to have a large diameter, and the opposite end is tapered and gradually reduced in diameter. The current collector is welded to the negative terminal plate, fitted into the boss of the sealing packing, and then assembled into the battery.

By the way, in current batteries, the negative electrode current collector is made of brass (
Copper-zinc alloy) is commonly used. Reasons for this include: (1) Brass itself has excellent electrical conductivity; (2) Since brass is very easily frozen, it is compatible with frozen powdered zinc in the negative electrode.

<Problems to be Solved by the Invention> However, current alkaline batteries using brass negative electrode current collectors have the following problems. First, since both copper and zinc are expensive, brass, which is an alloy of these, is also expensive, and the price of the negative electrode current collector increases, which becomes a major obstacle in reducing battery loss. In addition, there is a large difference in melting point between the negative electrode terminal plate made of a nickel-plated plate made of iron or a clad plate made of stainless steel, and the negative electrode current collector made of brass. This tends to cause cracks or poor welding strength due to insufficient melting. In particular, if the welding is excessive, the sealing part of the sealing packing will be damaged by the flashing of the welded part, which will lead to a decrease in the leakage resistance of the battery. Furthermore, the thinner the negative electrode current collector, the more gelled negative electrode can be filled, and the longer the negative electrode current collector, the higher the current collection efficiency. However, brass negative electrode current collectors are easily deformed during processing and have poor workability. , it is not possible to obtain a thin and long piece with good accuracy, for example, if the diameter is 1.5 mm, the length is 3Q.
It is limited to about mm. In addition, dezincing occurs when the zinc in the brass is eluted during the first step after battery assembly, and as a result, the unevenness of the negative electrode current collector surface increases, the sealing performance between the sealing packing and the sealing packing deteriorates, and alkali creep occurs. It becomes easier. Furthermore, the fact that brass is easily frozen by the mercury of frozen zinc in the negative electrode causes the problem that it becomes a source of impurities that promotes this alkali creep. For this reason, it is conceivable to use a negative electrode current collector made of iron, which does not have the above-mentioned drawbacks, but iron negative electrode current collectors are extremely difficult to freeze, and, for example, they do not absorb oxygen in the air before being incorporated into a battery. At present, the surface of the battery becomes rusty, and this rust corrodes the zinc powder inside the battery, becoming a source of gas generation, making it practically unusable.

〈Means for solving problems〉 The present inventor investigated ω1 in order to solve the above problems.

Upon investigation, we found that when iron-nickel alloy plating is applied to an iron base, this alloy plating layer has excellent corrosion resistance, prevents the base iron from rusting, and allows for multiple uses. In alkaline batteries, the material used as the negative electrode current collector is extremely susceptible to freezing, and even when using a material that is extremely compatible with the frozen powder zinc in the gelled negative electrode, the extent to which it contributes to improving the battery's discharge performance is limited. This invention was completed based on the knowledge that the use of metals such as brass that freeze too easily is undesirable from the standpoint of improving leakage resistance, resulting in a decrease in the overall performance of the battery. This is what led to this.

That is, the alkaline battery of the present invention is formed into a predetermined shape,
The gist of the present invention is to use an iron base negative electrode current collector plated with an iron-nickel alloy.

<Function> In the iron base negative electrode current collector plated with iron-nickel alloy as described above, the iron-nickel alloy on the surface easily freezes to some extent, so it is compatible with the frozen powdered zinc in the negative electrode, and also, Compared to brass negative electrode current collectors, the material is cheaper, so there is very little loss, and it is easy to weld with the negative electrode terminal plate, the welding strength is high, and there is no burrs at the welded part, which causes deformation during processing. Since it is difficult, a thin and long shape can be obtained with high precision, and there is no dezincing during storage. In addition, the iron-nickel alloy plating layer on the surface has excellent corrosion resistance, and since this alloy plating is applied to the entire surface after being formed into a predetermined shape, the surface is reliably covered with the alloy plating layer, and as a result, the base material is coated with the alloy plating layer. It can completely prevent certain iron from rusting (turning into iron oxide).

<Example> The first example shows an example in which the present invention is applied to a cylindrical alkaline battery.
In the figure, the inner circumferential surface of a bottomed cylindrical positive electrode can 1 made of a nickel-plated iron plate or the like is coated with manganese dioxide, which is a positive electrode active material, a conductive agent such as scaly graphite, and KOH or NaOH.
An alkaline electrolyte such as an aqueous solution is added, and after mixing, the positive electrode mixture 2 is press-molded into a hollow cylindrical shape. A gel negative electrode 4 mainly composed of frozen zinc powder is housed in the hollow part of the positive electrode mixture 2 via a separator 3 made of polypropylene nonwoven fabric, etc. A disc-shaped negative electrode terminal plate 8 made of a plated plate, etc.
A negative electrode current collector 5 whose head 5a is welded is embedded. The negative electrode current collector 5 is made by plating the surface of an iron base with an iron-nickel alloy, and around the welded part with the negative electrode terminal plate 8, there is an annular sealing gasket 1-6 made of polyethylene 9 polypropylene or the like. A boss portion 6a is fitted, and a sealing cap 7 is fitted to the lower end of the boss portion 6a.

The manufacturing process of the negative electrode current collector 5 and the battery assembly process will be explained using FIGS. 2(A) to 2(C). First, a thin iron rod of a predetermined size is molded into a suitable mold to form a large-diameter head 5a and an extremely small-diameter header 5C at one end, and a taper part whose diameter is gradually reduced at the other end and whose leading edge is rounded. 5b each having a second
It is processed into the shape shown in Figure A, and after processing, the surface is plated with an iron-nickel alloy to produce the negative electrode current collector 5. While pressing the head 5a of the negative electrode current collector 5 against the negative electrode terminal plate 8,
After welding and melting the head portion 5C to integrate the two, the tapered portion 5b of the negative electrode current collector 5 is sealed with a sealing cap 7 fitted onto the boss portion 6a in advance as shown in FIG. 2(B). Place it over the insertion hole 6b of the gasket 1-6 and push it all the way to the base to integrate the two. Then, this integrated product is placed over the opening 1b of the positive electrode can 1 containing the positive electrode mixture 2, the separator 3, and the gelled negative electrode 4, and the negative electrode current collector 5 is placed over the gelled negative electrode 4.
1 until the opening of the positive electrode can and the sealing gasket 1-6 are in contact with each other, and then the opening of the positive electrode can 1 is narrowed and caulked to form a cylindrical alkaline battery as shown in FIG.

<Effects of the Invention> As explained above, the alkaline battery of the present invention uses an iron base negative electrode current collector formed into a predetermined shape and plated with an iron-nickel alloy. By using a current collector, the manufacturing cost of the current collector is reduced, and the cost of the battery can be reduced accordingly. Furthermore, since the negative electrode current collector can be made to have a desired small diameter and long dimension, the amount of gelled negative electrode packed can be increased, the current collection efficiency can be improved, and the battery discharge performance can be improved. In addition, it is easy to weld to the negative electrode terminal plate and the welding strength is high even when using a thin negative electrode current collector, so workability during battery assembly can be improved and productivity can be improved. Furthermore, there is no burr generation at the welded part, and the desired shape can be obtained with high accuracy due to improved workability, so there is no damage to the sealing part of the sealing packing. In addition, unlike brass negative electrode current collectors, there is no surface dezincification during storage, and there is less progression of alkali creep due to icing, which has various practical effects such as improving the wet liquid resistance of the battery. play.

[Brief explanation of drawings]

Figure 1 is a sectional view showing an embodiment of the present invention, Figure 2 (A)
-(C) are explanatory diagrams showing the manufacturing process of the example. DESCRIPTION OF SYMBOLS 1... Positive electrode can, 2... Positive electrode mixture, 4... Gel-like negative electrode, 5... Negative electrode current collector, 6... Sealing gasket 1-.
8... Negative terminal plate.

Claims (1)

[Claims] 1. An alkaline battery characterized by using an iron base negative electrode current collector formed into a predetermined shape and plated with an iron-nickel alloy.