JPH0443553A - Thin type sealed battery - Google Patents

Abstract

PURPOSE:To shut out the ooze of an electrolyte at the time of thermal deposition by so forming a hot melt type adhesive as to have larger thickness inside and smaller thickness outside respectively before starting a thermal deposition process. CONSTITUTION:The material of a hot melt type adhesive 6 is denatured polyethylene. The adhesive 6 has a trapezoidal sectional area, and the inner thickness thereof is larger than the outer thickness. Immediately after a heating plate 7 comes down and starts depositing thermally battery components laid on a fixed table 8, an outer metal thin plate 1 used as a positive terminal and an outer metal thin plate 5 as a negative terminal, come in contact with the hot melt type adhesive 6. As a result, an electrolyte can be first shut out, and thermal deposition can be continued in a succeeding process in a condition free from the ooze of the electrolyte.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a thin sealed battery whose outer periphery is thermally welded with a hot melt adhesive.

Conventional technology Conventionally, ultra-thin sealed batteries whose outer periphery is thermally welded with a hot-melt adhesive can be made extremely thin by using a hot-melt adhesive for insulation sealing, making them suitable for power supplies for IC cards, etc. It has been adopted.

As shown in FIG. 4, its cross-sectional shape is such that a positive electrode material 2, a separator 3 impregnated with electrolyte, and a negative electrode material 4 are laminated on a positive electrode terminal/exterior metal thin plate 1, and then a negative electrode terminal/exterior metal thin plate 1 is laminated. 5 is laminated and hot melt adhesive 6 is placed around the outer periphery.
It is made by heat welding.

Such ultra-thin batteries are disclosed in Japanese Patent Application Laid-open No. 60-22, for example.
Solid electrolyte batteries in which the electrolyte is not a liquid, such as those disclosed in Japanese Patent No. 0553, and batteries that require only a small amount of liquid have been commercialized.

Problems to be Solved by the Invention However, for example, next-generation batteries require a sufficient amount of electrolyte within the battery, and in such cases, when hot-melt adhesives are thermally welded, the electrolyte may stain and cause damage to the adhesive surface. There was a problem with it getting wet.

An object of the present invention is to enable highly reliable thermal welding of hot melt adhesives in thin sealed batteries whose outer periphery is insulated and sealed with a hot melt adhesive, even in the case of batteries that require a sufficient amount of electrolyte. shall be.

Means for Solving the Problems The present invention has been made to achieve the above objects.
This method is characterized by using a hot-melt adhesive that is shaped before heat welding so that the inner thickness is large and the outer thickness is small.

Even in the case of thin sealed batteries that require a sufficient amount of electrolyte, there is no leakage of electrolyte during thermal welding, and there is no adhesion failure due to wetting of the adhesive surface. .

Example An embodiment of the present invention will be described.

FIG. 1 is a sectional view showing the stacked state of the ultra-thin sealed battery of the present invention before entering the hot-melt adhesive thermal welding process. The internal structure of the battery is the same as the conventional one, in which the battery internal elements, such as a positive electrode material 2, a separator 3 impregnated with an electrolytic solution, and a negative electrode material 4, are laminated in order on an exterior metal thin plate 1 that also serves as a positive electrode terminal, and then a negative electrode Exterior metal thin plates 5 which also serve as terminals are laminated, and a hot melt adhesive 6 disposed around the outer periphery is thermally welded.

The material of the hot melt adhesive 6 is modified polyethylene. Its shape is trapezoidal in cross section, and the inner thickness is 0.31
, the outer thickness is 0.1■.

FIG. 2 is an enlarged view of the hot melt bonding part in the heat welding process. (a) is the same as FIG. 1, and shows only a stacked state. (b) is immediately after the hot plate 7 has descended and started thermally welding the battery components placed on the fixing base 8, and the exterior metal thin plate 1 which also serves as a positive electrode terminal and the exterior metal thin plate 5 which also serves as a negative electrode terminal are shown in FIG. A state in which it is in contact with hot melt adhesive 6 is shown.

(C) shows a state in which the hot melt adhesive 6 gradually melts and flows as the hot plate further descends. (d
) indicates a state in which thermal welding is completely completed.

As can be seen from FIG. 2, the inside of the trapezoidal cross section of the hot melt adhesive 6 first hits the exterior metal thin plate 1 which also serves as a positive electrode terminal and the exterior metal thin plate 5 which also serves as a negative electrode terminal. Therefore, the electrolyte can be shut off first, and heat welding can be carried out in other parts without any electrolyte seeping out.

Next, for testing, 50 batteries were made into which 2 cc of electrolyte was injected, and an airtightness test was conducted. As a result, there were no thermal welding (adhesion) defects due to seepage of the electrolyte.

In the ultra-thin sealed battery of the present invention, when the amount of electrolyte increases further, it is more effective to increase the pressure of the atmosphere at the point shown in FIG. 2(b).

Further, FIG. 3 shows cross-sectional shapes of two types of hot melt adhesives as examples in which the present invention is effective.

(a) shows the trapezoidal cross-sectional shape shown in FIGS. 1 and 2. As mentioned above, since the inside thickness of the trapezoidal cross section is large and the outside thickness is small, when thermocompression bonding is performed, first the exterior metal thin plate 1 which also serves as the positive electrode terminal and the exterior metal thin plate 5 which also serves as the negative electrode terminal are bonded. It is possible to block liquid from coming out from the inside upon contact. However, this shape
Quite difficult to mold. Since it has a trapezoidal cross section, injection molding or the like may be used as a molding method, but since it is thin, it cannot be manufactured with high precision. A certain degree of precision is required to obtain the effects of the present invention. In the test, injection molded products were inspected and only good products were selected and used. (b
) is a hot melt adhesive 6 having a T-shaped cross section. The shape provides the same effect as that shown in FIG. 3(a) and can be easily molded by bonding films of uniform thickness together.

Effects of the Invention As described above, according to the present invention, since a hot melt adhesive having a large inner thickness and a small outer thickness is used as a hot melt adhesive, when heat welding, the hot melt adhesive is When the inner edge of the melt adhesive comes into contact with the exterior metal plate that also serves as the positive electrode terminal and the exterior metal plate that also serves as the negative electrode terminal, it is possible to block the electrolyte from seeping from inside at that point, and the adhesive It has become possible to completely eliminate adhesion failures due to wet surfaces. Furthermore, thermal welding becomes more effective by increasing the pressure of the external atmosphere. As a result, even when a sufficient amount of electrolyte is injected into the battery, it has become possible to completely eliminate thermal welding defects caused by hot melt adhesives.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an ultra-thin sealed battery showing a stacked state of battery components before entering the hot-melt adhesive thermal welding process in an embodiment of the thin sealed battery of the present invention, and FIG. fa) fb) are enlarged cross-sectional views of the hot melt bonding part in the heat welding process of the present invention, FIGS. 3(a) and (b).
) is a sectional view showing the shapes of two types of hot melt adhesives of the present invention, and FIG. 4 is a sectional view of a conventional ultra-thin sealed battery. 1 is a positive electrode terminal and an exterior metal thin plate, 2 is a positive electrode material, 3 is a separator, 4 is a negative electrode material, 5 is a negative electrode terminal and an exterior metal thin plate, and 6 is a hot melt adhesive.

Claims (1)

[Claims] In a thin sealed battery whose outer periphery is thermally welded with a hot melt adhesive, the shape of the hot melt adhesive is
A thin sealed battery characterized by using a hot-melt adhesive that has a shape that is thicker on the inside and smaller on the outside before heat welding.