JPH02253556A - Manufacture of positive electrode body of flat cell - Google Patents

Abstract

PURPOSE:To eliminate the unevenness of form and weight in a simple method and to realize a uniform discharge capacity by providing a process to feed a specific amount of positive electrode composite paste to a filling pattern and to dry, and a process to apply a pressure to the dried paste to form in the pattern. CONSTITUTION:To a mixture powder of 90wt.% of manganese dioxide and 1wt.% of graphite, a dispersion liquid of 1wt.% of polyacrylic acid, 2wt.% of polyfluoroethylene, and the water, is mixed and kneaded, to prepare a positive electrode composite paste 1. The paste 1 is fed to a stainless filling pattern 2 by a dispenser 3 at a specific amount, the pattern 2 is vibrated horizontally to make the thickness constant, and it is dried in a drier 4. The dired paste 5 is pressurized and formed by a press 6, and removed from the pattern 2 to obtain a positive electrode formation 7. The formation 7 is made into a positive electrode body 11, and assembled together with a positive electrode terminal plate 15 made of a stainless steel, a negative electrode terminal 16 to which a metal lithium 13 is attached, and a separator 12, by an insulating sealing plate 14, and a flat cell is made up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] [Industrial Field of Application] The present invention relates to a method for producing a positive electrode molded body in a pre-drying step of a flat battery positive electrode body.

[Conventional technology]

In recent years, as electronic desktop calculators and electronic devices have become smaller and thinner, there has been an increasing demand for flat batteries as power sources for them. Among these, ultra-thin, highly reliable flat batteries with a thickness of 0.5+em or less, which are typically used in card-type calculators, IC cards, etc., are strongly desired.

Conventionally, positive electrode molded bodies used in flat batteries have generally been manufactured by the following method. That is, a positive electrode mixture using manganese dioxide as an active material is granulated, then supplied to a filling mold, weighed in mass, and then pressure molded to produce a positive electrode molded body.

[Problem to be solved by the invention]

However, in the conventional manufacturing method of positive electrode molded body, 0.5
When manufacturing a positive electrode molded body intended for a mm flat battery, the amount of positive electrode mixture supplied to the filling mold is lJ? Since it is a mouth, the accuracy of mass measurement is greatly affected, and the variation in thickness and weight of the positive electrode molded body after pressure molding becomes large, which becomes a problem.

In addition, the supplied powder cannot be controlled to a constant thickness in the filling mold, resulting in variations in thickness in the area direction of the positive electrode molded body after pressure molding, resulting in problems such as cracking and chipping. Ta.

The present invention includes a first step of supplying a certain amount of positive electrode mixture paste to a filling mold and then drying it, and a second step of press-molding the dried paste in the filling mold within the mold. ,
The present invention aims to provide a manufacturing method for making the shape and thickness of a positive electrode molded body constant.

[Means to solve the problem]

In the present invention, a positive terminal plate with a dried positive electrode molded body and a negative terminal plate with metallic lithium arranged face each other with a separator interposed therebetween, and the outer periphery of both terminal plates is sealed with an insulating sealant. In the method for manufacturing a positive electrode body for a flat battery that can be opened, the positive electrode molded body is produced by a first step of supplying a certain amount of positive electrode mixture paste to a filling mold and then drying the same, and a step of drying the paste in the filling mold. This is a manufacturing method characterized by having a second step of press-molding in the mold.

When preparing the positive electrode mixture paste, it is preferable to add a thickener such as a water-soluble polymer material such as polyacrylic acid. The reason for this is that it prevents the liquid from flowing out from the dispenser when supplying the paste, and enables constant and accurate quantitative supply to the filling mold.

[For production]

According to the present invention, by supplying a certain amount of positive electrode mixture paste into a filling mold, the process up to pressure molding can be performed within the mold, thereby eliminating variations in weight and thickness of positive electrode molded bodies. ,
It is possible to make the shape of the positive electrode molded body constant.

Furthermore, in the drying process, the edges of the positive electrode mixture paste are in contact with the filling mold, so in the dried paste after this process, the edges become convex with respect to the center, and the positive electrode mixture paste after pressure molding It becomes possible to strengthen the peripheral parts of the body.

〔Example〕

The present invention will be explained in detail below.

First, in Fig. 1, a dispersion of 1% by weight of polyacrylic acid, 1% by weight of polytetrafluoroethylene 21H and water is mixed and stirred into a mixed powder of 90% by weight of manganese dioxide and 10% by weight of graphite, and a viscous positive electrode is formed. A mixture paste was prepared.

Next, for example, opening size 20mm x 20 fins, depth 1G+
Using a dispenser 3, 0.2 g of the paste 1 was quantitatively supplied to a stainless steel filling mold 2 (U). Next,
After vibrating the filling mold 2 in the horizontal direction to make the thickness of the paste 1 in the mold 2 constant, it was dried in a dryer 4 at 100"C for 20 minutes, and the dried paste 5 in the above state was further dried. 5
The positive electrode molded body 7 with a thickness of 0.25 mrs was manufactured by performing pressure molding with a press 6 for 3 seconds under a load of 1.son/cj, and then peeling it off and taking it out from the filling mold 1.

Furthermore, in FIG. 2, the positive electrode molded body 7 was dried at 250° C. for 3 hours to form a positive electrode body 11, and the external size was 35 mm.
A positive electrode was manufactured by disposing it on a positive electrode terminal plate 15 made of stainless steel with a diameter of 35 m and a thickness of 0.03 am.

Next, the positive electrode and the negative electrode, in which metal lithium 13 is crimped onto the negative electrode terminal plate 16, are stacked facing each other with the separator 12 in between.
A flat battery (A) having a thickness of 0.5 a+m was manufactured by sealing the outer periphery of the battery.

Comparative Example A positive electrode mixture with a particle size of 30 to 60 esh was mass-weighed into a filling mold in the powder filling process of a rotary press molding machine, and 5
Pressure was applied for 3 seconds under a load of to1%/cj to obtain a positive electrode molded body. A flat battery (B) was manufactured in the same manner as in the example below.

Here, regarding the present example and comparative example, the occurrence of defects in the positive electrode molded body, variations in weight and thickness, and variations in discharge capacity after battery assembly were determined for each IQ (1IJ1 for each piece), and the results were evaluated. It is shown in Table 1.

In Table 1, it is clear that Example (A) is effective in eliminating chipping of the positive electrode molded body, variations in weight and thickness, and variations in discharge capacity after battery assembly.

Table 1 1... Positive electrode mixture paste 3... Dispenser 5...Dried paste 7... Positive electrode molded body 15...Positive terminal plate 2...Filling type 4...Dryer 6... Breath 11... Positive electrode body 16...Negative terminal plate

Claims (2)

[Claims] (1), the positive electrode body (7) is connected to the positive electrode terminal plate (15) on which the dried positive electrode body (11) is arranged, and the negative electrode terminal plate (16) on which metallic lithium (13) is arranged, and a separator (12) is connected. The positive terminal plate (15) and the negative terminal plate (
In the method for manufacturing a flat battery positive electrode body in which the outer peripheral portion of the positive electrode molded body (16) is sealed with an insulating sealing body (14), the positive electrode molded body (
7) consists of a first step of supplying a certain amount of positive electrode mixture paste (1) to the filling mold (2) and then drying it, and a second step of pressure-molding the dried paste (5) in the filling mold (2). 1. A method for producing a flat battery positive electrode body, comprising two steps. (2) The positive electrode mixture paste (1) comprises a mixture of a positive electrode active material, a conductive agent, polytetrafluoroethylene, a water-soluble polymeric substance, and water. A method for producing a flat battery positive electrode body according to item 1.