JPH0398255A - Manufacture of flat battery - Google Patents

Abstract

PURPOSE:To prevent shift at the time of fusing between terminal boards and insulating sealing bodies by a method wherein terminal boards of positive and negative poles different in outer diameter are used. CONSTITUTION:To the periphery of terminal boards 1,2 of positive and negative poles different in outer diameter, insulating sealing bodies 7, 8 corresponding to the outer sizes of the terminal boards 1, 2 are fused. When the terminal boards 1, 2 and the insulating sealing bodies 7, 8 are to be fused, the terminal boards 1, 2 and the insulating sealing bodies 7, 8 can be put into a recess formed of guides 30, 40 of a sealing body.terminal board fusing device and lower heater chips 32, 42 without shift in position. Therefore a highly reliable flat battery having good sealability and free from leakage of battery electrolyte in the battery or vapor transmission into the battery can be manufactured in a simple process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for manufacturing a flat battery, and particularly to a method for manufacturing a flat battery with an improved sealing process.

(Prior Art) In recent years, as electronic devices such as desktop calculators and electronic wristwatches have become thinner, demand for flat batteries as power sources for electronic devices has increased. In particular, among these electronic devices, flat batteries with a total thickness of 0.51 or less and high reliability are strongly desired as power sources for card-type electronic devices such as card-type calculators and IC cards. It is rare.

Generally, in the manufacturing method of button-shaped or coin-shaped flat batteries, a method is adopted in which an insulating packing is used and a current collector is bent to form a sealed opening. However, this method has a limit of reducing the total thickness of the battery to about 1.0 mm due to structural and processing constraints.

For this reason, a structure as shown in FIG. 2 has been proposed as an ultra-thin flat battery with a total thickness of 0.51 mm or less. That is, this flat battery has a positive terminal plate l
1 and the negative electrode terminal plate 12, a power generation unit 13 consisting of a negative electrode sheet 14, a separator l5, and a positive electrode mixture l6 is installed.
is located. Frame-shaped insulating sealing bodies 17 and 18 made of heat-fusible resin are provided at the peripheral edges of the positive terminal plate 1l and the negative terminal plate l2 so as to surround the power generation unit l3 and to face each other. It is set in. The power generation unit 13 is sealed inside the battery by fusing these insulating sealing bodies 17 and 18. This flat battery is ultra-thin with a total thickness of 0.51 mm or less, so even if an electrical conductor comes into contact with the side surface of the battery, which has a thickness of 0.5 mm or less, external short circuits will not occur.For example, the positive electrode Terminal board 11
The outer dimension of the negative electrode terminal plate 12 is made smaller, and one terminal plate is retracted into the other terminal plate.

By the way, the above-mentioned flat battery has conventionally been manufactured by the following method.

First, as shown in FIG. 5, a positive terminal plate 11 and a frame-shaped insulating sealing body l7 having the same outer dimensions as the positive terminal plate 11 are formed from a guide 50 of a sealing body/terminal plate fusion splicer and a lower heater chip 52. The upper heater chip 5l is lowered in the direction of the arrow to heat and fuse the insulating sealing body L7 to the peripheral edge of the positive electrode terminal plate 1l.

In heating and fusing the insulating sealing body 17 and the positive terminal plate 11, the insulating sealing body 17 is heated and fused by the upper heater chip 5l on the terminal plate side so as not to be welded to the lower heater chip 52.

Further, as shown in FIG. 6, the negative terminal plate 12 and the frame-shaped insulating sealing body 18 having a smaller outer diameter than the negative electrode terminal plate 12 are connected to the guide 60 of the sealing body/terminal plate fusion machine and the lower heater chip 62.
into the recess formed by the upper heater chip 6l.
is lowered in the direction of the arrow to heat and fuse the insulating sealing body 18 to the peripheral edge of the negative electrode terminal plate 12.

The insulating sealing body 18 and the negative terminal plate 12 are also heated and fused by the upper heater chip 61 on the terminal plate side.

Next, the positive electrode terminal plate 1 {to which the insulating sealing body l7 is fused,
The negative electrode terminal plate 12 to which the insulating sealing body l8 is fused is arranged so that the respective insulating sealing bodies 17 and 18 face each other, and the power generation unit 1 is placed between the positive electrode terminal plate 11 and the negative electrode terminal plate 12.
3, and the insulating sealing bodies 17 and 18 are fused together to produce a flat battery as shown in FIG. In this manufacturing method, by welding each insulating sealing body 17, 18 to each terminal board 11, 12 in advance, the insulating sealing body and the metal terminal plate are bonded together, compared to the case where one insulating sealing body is used. Since the adhesion strength is increased, the sealability of the battery is improved.

However, in the conventional manufacturing method, it is necessary to fuse the negative electrode terminal plate 12 and the insulating sealing body 18, which have different outer dimensions, so that as shown in FIG. There is a risk of misalignment. In this state, when the upper heater chip 6l is lowered in the direction of the arrow and heated, the insulating sealing body 18 comes into contact with the heater chip 61 and is fused. As a result, (1) the insulating sealing body 18 causes strings and cracks, resulting in defective products such as poor appearance; (2) the heater chip 6l to which the insulating sealing body 18 is fused is used to produce the next flat battery; If the insulating sealant is fused, the heating will be insufficient and the sealability will deteriorate, causing the electrolyte in the battery to leak or moisture to permeate into the battery, resulting in a flat surface. This causes problems such as a decrease in the reliability of the battery.

5 (Problems to be Solved by the Invention) The present invention has been made to solve the above-mentioned conventional problems, and aims to provide a method for easily manufacturing highly reliable ultra-thin flat batteries. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides positive and negative terminal boards having different outer dimensions, and a frame corresponding to the outer dimensions of the terminal board on the peripheral edge of one of the terminal boards. An insulating sealing body made of heat-fusible resin is fused to form a shape, and an insulating sealing body made of heat-fusible resin is fused to the peripheral edge of the other terminal board to form a frame shape corresponding to the outer dimensions of the terminal board. a step of arranging each of the terminal boards so that their insulating sealing bodies face each other, interposing a power generation unit between these terminal boards, and then fusing the insulating sealing bodies together; A method for manufacturing a flat battery, comprising:

Hereinafter, the present invention will be explained in detail with reference to the drawings.

First, as shown in FIG. 3, the positive terminal plate 1 and an insulating sealing body 7 made of a heat-fusible resin and having a frame shape with the same outer dimensions as the positive terminal plate 6 are attached to the guide 30 of the sealing body/terminal plate fusion machine. The positive electrode terminal plate 1 is then inserted into the recess formed by the heater chip 32, and the upper heater chip 3l is lowered in the direction of the arrow to heat and fuse the insulating sealing body 7 to the peripheral edge of the positive electrode terminal plate 1. At this time,
The inner dimensions of the guide 30 correspond to the outer dimensions of the positive electrode terminal plate 1 and the insulating sealing body 7. Insulating sealing body 7 and positive terminal plate 1
In order to prevent the insulating sealing body 7 made of a thermofusible resin from being fused to the lower heater chip 32, the heat fusion is normally performed by heating with the upper heater chip 31 on the terminal board side.

Further, as shown in FIG. 4, for example, a negative electrode terminal plate 2 having smaller outer dimensions than the positive electrode terminal plate 1 and an insulating sealing body 8 made of heat-fusible resin having a frame shape and having the same outer dimensions as the negative electrode terminal plate 2 are arranged. ,
The insulating sealing body 8 is inserted into the recess formed by the guide 40 and the lower heater chip 42 of the sealing body/terminal plate fusion splicer, and the upper heater chip 41 is lowered in the direction of the arrow to attach the insulating sealing body 8 to the peripheral edge of the negative electrode terminal plate 2. Heat and fuse. At this time, Guy lower 4
The inner dimensions of o correspond to the outer dimensions of the negative terminal plate 2 and the insulating sealing body 8. The insulating sealing body 8 and the negative terminal plate 2 are usually thermally fused by heating using the upper heater chip 4l on the terminal plate side.

Next, the positive terminal plate 1 to which the insulating sealing body 7 has been fused and the negative terminal plate 2 to which the insulating sealing body 8 has been fused are connected to the insulating sealing body 7.
8 are arranged so as to face each other, and these terminal plates 1.2
After the power generation unit is interposed between them, the sealing bodies 7 and 8 are fused and sealed together to form an insulating sealing body 7.8 as shown in FIG. 1 between the negative electrode sheet 4, separator 5 and A flat battery surrounding a power generation unit 3 made of a positive electrode mixture 6 is manufactured.

The terminal plate 1.2 is made of, for example, a stainless steel plate, a nickel plate, a titanium plate, or the like. Said positive and negative terminal plate 1
．． 2, an example was shown in which the external dimensions of the negative terminal plate 2 were smaller than those of the positive terminal plate l, but the external dimensions of the positive terminal plate 1 may be smaller than the negative terminal plate 2.

The heat-fusible resin forming the insulating sealing bodies 7 and 8 is preferably modified polyethylene containing a carboxyl group, which has the effect of improving the adhesion effect to the positive terminal plate and the negative terminal plate made of metal. Examples of such modified polyethylene include those obtained by copolymerizing or graft polymerizing an ethylene monomer or polyethylene with an unsaturated carboxylic acid. Examples of the unsaturated acid used here include acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid, and maleic anhydride. Among these, particularly preferred are:
NaSZn between the molecules of ethylene-methacrylic acid copolymer
These are ionomer resins crosslinked with metals such as, copolymers or graft polymers of the ionomer resins and unsaturated carboxylic acids, and these resins have excellent adhesive effects.

Maleic anhydride is suitable as the unsaturated carboxylic acid used here.

(Function) Since the method for manufacturing a flat battery of the present invention uses terminal plates for positive and negative electrodes having different outer diameters, the flat battery obtained is an ultra-thin battery with a total thickness of 0.51 or less. Even if an electrical conductor comes into contact with the side surface of the terminal board, there will be no external short circuit because one terminal board is retracted from the other terminal board.

In addition, as shown in FIG. 3 and FIG.
, 2, so when welding the terminal boards 1, 2 and the insulating sealing bodies 7, 8, the guide of the sealing body/terminal plate fusion machine is used. The terminal plates 1, 2 and the insulating sealing member 7.8 can be inserted into the recess formed by the lower heater chip 30.40 and the lower heater chip 32.42 without causing any positional displacement. As a result, the upper heater chip 31.2 to be heated is caused by the misalignment between the terminal plate 1.2 and the insulating sealing bodies 7, 8. 41 is the terminal plate 1.
Since contact with the insulating sealing body 7.8 on the opposite side of the insulating sealing body 2 can be prevented, it is possible to prevent the insulating sealing body from becoming stringy or fracturing.

Furthermore, an insulating sealing body 7 to the upper heater chip 31, 32
, 8 can solve the problem of insufficient heating of the insulating sealing body 7.8 in the next process. Therefore, the sealability is good, and the electrolyte inside the battery does not leak or moisture permeates into the battery, making it possible to manufacture highly reliable flat batteries using a simple process. .

(Example) Examples of the present invention will be described in detail below.

Example 1 First, as shown in Fig. 3, a SUS304 stainless steel plate is press-worked so that the area excluding the periphery is bent into a trapezoidal cross section, and a positive electrode mixture, which will be described later, is applied to the side to which the sealing body is fused. A positive electrode terminal plate l having outer dimensions of 23 mm x 231 Ilm and a frame-shaped insulating sealing body 7 made of an ionomer resin and having an outer dimension equal to that of the positive electrode terminal plate 1 and a thickness of 50 μm are assembled into a sealing body/terminal plate fusion. It is inserted into the recess formed by the guide 30 of the landing gear and the lower heater chip 32. Note that the inner diameter dimension of the guide 30 is the same as that of the positive electrode terminal plate 1.
It is equal to the outer diameter of Subsequently, the upper heater chip 31 was lowered in the direction of the arrow, and the insulating sealing body 7 was heat-sealed to the peripheral edge of the positive electrode terminal plate 1 under conditions of a temperature of 200° C., a pressure of 1 kg/cIIl2, and a welding time of 5 seconds. The positive electrode mixture is a mixture of 90% by weight of γ-βMn02 obtained by firing manganese dioxide at 350°C as an active material, 5% by weight of graphite powder as a conductive material, 1% by weight of polyacrylic acid as a binder, and water. Then, 3% by weight of desversion of polytetrafluoroethylene is added to this mixture in terms of solid content to make a paste, and this paste is applied to the inside of the upper side of the trapezoidal part of the positive terminal plate 1. It was prepared by drying.

In addition, as shown in Figure 4, the outer dimensions of the negative electrode sheet made of metallic lithium are 22.4 mm x 22.4 mm.
A negative electrode terminal plate 2 made of a stainless steel plate with a diameter of 22.4 mm and a thickness of 30 μm and a rod-shaped insulating sealing body 8 made of an ionomer resin and having an outer dimension equal to that of the negative electrode terminal plate 2 and a thickness of 80 μm are combined into a sealing body. It is inserted into the recess formed by the guide 40 and the lower heater chip 42 of the terminal plate fusion machine. Note that the inner diameter dimension of the guide 40 is the same as that of the negative electrode terminal plate 2.
is equal to the outer diameter of Subsequently, the upper heater chip 4l was lowered in the direction of the arrow, and the insulating sealing body 8 was heat-fused to the 1 2 peripheral edge of the negative electrode terminal plate 2 under the conditions of a temperature of 200°C, a pressure of 1 kg/eli2, and a fusion time of 5 seconds. .

Next, the positive electrode terminal plate l to which the insulating sealing body 7 is fused and the negative electrode terminal plate 2 to which the insulating sealing body 8 is fused are arranged so that the insulating sealing body 7 and the insulating sealing body 8 face each other. Mixture 6
and the negative electrode sheet 4 through a separator 5 made of polypropylene nonwoven fabric impregnated with an electrolytic solution.
2 was pressurized and fused from both sides at a temperature of 180°C, a pressure of 3 kg/c...2, and a fusion time of 3 seconds to seal the opening. In this way, as shown in FIG. terminal board l
and a frame-shaped insulating sealing body 7 on the periphery of the negative terminal plate 2.
8 surrounding the power generation unit 3 were manufactured.

Comparative Example 1 In heat-sealing an insulating sealing body to a negative electrode terminal plate, a negative electrode terminal plate having the same dimensions as the example having a smaller outer diameter was attached to a frame-shaped insulating sealing body made of ionomer resin with outer dimensions of 23 mm x 23 m + n. 100 flat batteries were manufactured under the same conditions as in Example 1 except that 1 3 was fused.

The number of defects in the obtained flat batteries was measured. In addition, products with poor appearance due to stringiness or flaking of the insulating sealant were classified as defective products. The mucilage is shown in Table 1 below.

In addition, the obtained flat battery was heated at a temperature of 45°C and a relative humidity of 93°C.
% condition for 60 days, the internal resistance before and after storage was measured, and the average of 100 flat batteries was determined.

The results are shown in Table 2 below.

Table 1 Table 2 Table 1 4 As is clear from Table 1, the flat batteries manufactured by the method of the present invention had zero defective products, whereas Comparative Example 1
It can be seen that the number of defective flat batteries was extremely high at 43. Furthermore, as is clear from Table 2, the rice flat battery produced by the method of the present invention shows a slight increase in internal resistance after storage, whereas the flat battery of Comparative Example 1 shows a slight increase in internal resistance after storage. It can be seen that the internal resistance of this is,
In the flat battery of Comparative Example 1, when the terminal plate and the insulating sealing body, which had different outer dimensions, were thermally fused, the terminal plate and the insulating sealing body were misaligned, and the insulating sealing body was attached to the heater chip. This can lead to poor appearance such as stringiness and crackling, and the heating by the heater chip is insufficient, which impairs the sealability.If the flat battery is stored in hot and humid conditions, the adhesion It is thought that moisture permeated through the imperfections, and the lithium in the negative electrode sheet reacted with water to form a film on the lithium surface, increasing the internal resistance of the battery.

1 5 [Effects of the Invention] As detailed above, according to the present invention, it is possible to prevent misalignment when the terminal board and the insulating sealing body are fused together, so that the number of defective products can be reduced, and the airtightness is excellent. It is possible to provide a method for manufacturing a highly reliable ultra-thin flat battery with a total thickness of 0.5 mm or less that prevents short circuits.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a flat battery obtained by the manufacturing method of the present invention, FIG. 2 is a sectional view showing an example of a flat battery obtained by a conventional manufacturing method, and FIGS.
The figure is a cross-sectional view showing an example of the step of fusing the terminal plate and the insulating sealing body in the manufacturing method of the present invention, and FIGS. 5 and 6 show the welding of the terminal plate and the insulating sealing body in the conventional manufacturing method. FIG. 7 is a cross-sectional view illustrating an example of the process of performing the process, and FIG. 7 is a cross-sectional view for explaining the problems of the conventional manufacturing method. l... Positive electrode terminal plate, 2... Negative electrode terminal plate, 3... Power generation unit, 4... Negative electrode sheet, 5... Separator, 6... Positive electrode mixture, 7... Insulation Sealing body, 8...
Insulating sealing body, 1 6 30. 40... Guide, 31, 32, 41.42... Heater chip. 12 Figure 2 1 7 Figure 3 42

Claims (1)

[Claims] Prepare positive and negative terminal boards with different outer dimensions, and fuse an insulating sealing body made of heat-fusible resin with a frame shape corresponding to the outer dimensions of the terminal board to the peripheral edge of one terminal board. A step of fusing an insulating sealing body made of heat-fusible resin and having a frame shape corresponding to the outer dimensions of the other terminal board to the peripheral edge of the other terminal board; A method for manufacturing a flat battery, comprising the steps of arranging the terminal plates so as to face each other and interposing a power generating unit between the terminal plates, and then fusing the insulating sealing bodies together.