JPS62133671A - Manufacture of button type alkaline cell - Google Patents

Abstract

PURPOSE:To contrive to stabilize and improve the performance of a cell by injecting the electrolyte to the positive electrode compound after placing the said positive electrode compound made by adding and mixing hydrophilic filler to a mixed powder of positive electrode active material and electro-conductive material onto the bottom plate of the positive electrode can from the aperture of the positive electrode can and forming by pressure in the positive electrode can. CONSTITUTION:The positive electrode compound 1 made by adding and mixing the cotton linter of 0.5wt% of the mixed powder of manganese dioxide (positive electrode active material) and scaled graphite (electro-conductive material) to the said mixed powder and pre-formed is placed on the bottom plate of the positive electrode can by moving towards the arrow I from the aperture 2a of the positive electrode can 2. Then a pressure of 1-1.5t/cm<2> is applied to the surface of the positive electrode compound 1 from the direction of the arrow P. After the forming by pressure is completed, 46ml of the electrolyte consisting of 40% aqueous solution of KOH are injected, and after this electrolyte is absorbed in the compound completely, the separator 3, gellike negative electrode 4, negative electrode terminal 5 and packing 6 for aperture sealing are assembled by means of the well known method to construct the cell.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a method for manufacturing a button-type alkaline battery, and more specifically, the present invention relates to a method for manufacturing a button-type alkaline battery. This relates to something that facilitates the liquid process.

<Prior art> Alkaline batteries constructed using a gelled negative electrode made by dispersing powdered zinc in a gelled state using an electrolyte consisting of an alkaline aqueous solution and a gelling agent are particularly suitable as batteries capable of continuous high-load discharge. There is a high demand in the field of small batteries such as button batteries. In such alkaline batteries, it is necessary to increase the discharge capacity of the positive electrode mixture in accordance with the increase in the discharge capacity of the negative electrode. For this reason, in the case of button-type alkaline batteries, a mixed powder consisting of a positive electrode active material such as manganese dioxide or silver oxide added with a conductive agent such as phosphorous graphite is placed in a coin shape under high pressure (1 to 1.5 t/cf). The positive electrode mixture is press-molded to increase the capacity of the positive electrode mixture inside the battery.

By the way, in this type of button-type alkaline batteries, so-called in-can molding is often performed, in which the positive electrode mixture is housed in a positive electrode can and then press-molded. The coin-shaped object is placed on the bottom of the positive electrode can through the opening of the positive electrode can, and the coin-shaped object is again pressure-formed inside the positive electrode can to closely fit into the inner surface of the positive electrode can, and then the electrolyte is injected into the positive electrode mixture. There is a method in which the liquid mixture is absorbed to form a battery positive electrode part, and then the negative electrode part consisting of a gelled negative electrode and a negative electrode can and this positive electrode part are assembled via a separator, a sealing gasket, etc. to form a finished product. Widely used.

<Problems to be solved by the invention> However, as the production speed of batteries increases, the pressurization of the mixture during the above-mentioned in-can molding is becoming instantaneous pressure molding in an extremely short time. Therefore, as shown in FIG. 2, the surface portion of the positive electrode mixture 8 is intensively compressed and becomes a dense layer 8a.

For this reason, when the electrolyte is injected in the subsequent process, the electrolyte and air in the mixture cannot be replaced smoothly due to the dense layer 8a on the surface of the mixture, which slows down the liquid absorption rate of the positive electrode mixture 8. However, since it takes time to absorb the required amount of electrolyte, there is a problem in that it causes a decrease in battery productivity. In addition, the long residence time from injection to assembly tends to cause changes in the electrolyte composition and deterioration of the active material in the mixture, and when the time from injection to assembly is limited, etc. In some cases, it is necessary to reduce the amount of liquid injected, and there are also problems in that the battery discharge performance tends to become unstable, and the discharge performance may deteriorate.

<Means for Solving the Problems> In view of the above-mentioned problems, the present invention uses a positive electrode mixture formed by adding and mixing a hydrophilic filler to a mixed powder of a positive electrode active material and a conductive agent. The method of manufacturing a button-type alkaline battery comprises placing a positive electrode mixture on the bottom surface of the positive electrode can, pressure-molding it inside the positive electrode can, and then injecting an electrolyte into the positive electrode mixture.

Examples of the above-mentioned hydrophilic fillers include cotton linters, nylon, vinylon, polyvinyl alcohol, polyethylene, and polypropylene. Materials such as cotton linters that have strong electrolyte absorption properties and are hydrophilic by themselves can be used as hydrophilic fillers as is, but materials with poor hydrophilic properties such as nylon may be soaked in an appropriate surfactant. It is effective to use a material that has been subjected to hydrophilic treatment.

In addition, the amount of the hydrophilic filler added is preferably Oo5 to 3% with respect to the mixed powder consisting of the positive electrode active material and the conductive agent. It is known that when the amount is more than this, the battery performance deteriorates significantly due to a decrease in the content of the positive electrode active material and conductive agent in the battery.

<Function> By adding a hydrophilic filler to the positive electrode mixture using the above means, it is possible to disperse the densification of the surface of the mixture during pressure molding in the positive electrode can. In addition, during injection, liquid absorption paths are secured within the hydrophilic filler or at the interface between this filler and the positive electrode active material and conductive agent, and the electrolyte is absorbed into the mixture through these liquid absorption paths. promoted.

<Example> Hereinafter, an example in which the present invention is applied to a button-type alkaline manganese battery will be described.

In Fig. 1 (A), 1 is a mixture of manganese dioxide (positive electrode active material) and phosphorous graphite (conductive agent) mixed with 0.5 wt ffi% cotton linter added to the mixed powder. This is a preformed positive electrode mixture, and this positive electrode mixture 1 is moved from the opening 2a of the positive electrode can 2 in the direction of the arrow and placed on the bottom surface of the positive electrode can. Next, as shown in FIG. 1 (8), the surface of the positive electrode mixture 1 is heated at 1 to 1.5 t/min from the direction of arrow P.
The mixture was pressurized in the positive electrode can by applying pressure with Cf. Note that 1a is a dense layer formed on the surface of the mixture.

After pressure molding, an electrolytic solution consisting of 40% KOH aqueous solution was added to the
After mfJ is injected and the electrolyte is completely absorbed into the mixture, the separator 3, the gelled negative electrode 4, the negative electrode terminal plate 5, and the sealing packing 6 are combined by a known method to form the L according to the present invention.
A P01 type button-type alkaline manganese battery (product A of the present invention) was made.

On the other hand, a conventional LR44 button-type alkaline manganese battery (conventional product B) was made in the same manner except that cotton linters were not added and mixed into the positive electrode mixture.

Regarding the above two batteries, the time (minutes) from injecting the electrolyte until the electrolyte was completely absorbed into the mixture was investigated. The results are shown in Table 1, and in the case of product A of the present invention, complete liquid absorption was achieved in only 215 hours compared to conventional product B.

Table 1 Although the above example shows the application of the present invention to a button-type alkaline manganese battery, it goes without saying that similar effects can be obtained with other types of button-type alkaline batteries.

<Effects of the Invention> According to the method for manufacturing a button-type alkaline battery of the present invention configured as described above, densification of the surface of the positive electrode mixture after pressure molding in the positive electrode can can be suppressed. In addition, since it is possible to promote liquid absorption inside the mixture during injection, the liquid absorption speed in the injection process can be dramatically increased, and battery productivity can be greatly improved accordingly. . In addition, the faster liquid absorption speed reduces the time from injection to assembly, reduces changes in electrolyte composition and deterioration of active materials, and ensures that sufficient mother electrolyte is always absorbed. Therefore, it has the effect of stabilizing and improving battery performance, and has great industrial utility value.

[Brief explanation of drawings]

FIGS. 1(A) to (C) are explanatory diagrams showing the manufacturing process in the example, and FIG. 2 is an explanatory diagram showing the state after in-can molding in the conventional example. 1.8...Positive electrode mixture, 2...Positive electrode can, 1a, Ba.
...Dense layer.

Claims (1)

[Claims] 1. A positive electrode mixture prepared by adding and mixing a hydrophilic filler to a mixed powder of a positive electrode active material and a conductive agent is placed on the bottom surface of the positive electrode can from the opening of the positive electrode can, and placed inside the positive electrode can. A method for manufacturing a button-shaped alkaline battery, which comprises injecting an electrolyte into a positive electrode mixture after pressure molding. 2. Claim 1, wherein the hydrophilic filler is cotton linter, nylon, vinylon, polyvinyl alcohol, polyethylene, or polypropylene.
The method described in section. 3. The amount of hydrophilic filler added to the mixed powder is 0.
．． 3. A method according to claim 1 or 2, characterized in that the amount is 5 to 3% by weight.