JPH0547360A - Thin battery - Google Patents

Abstract

PURPOSE:To provide a thin battery generating no defect on a seal portion when a terminal board and a seal body are sealed by heat deposition. CONSTITUTION:Terminal boards 1, 2 concurrently serving as current collectors are arranged above and below a power generating element overlapped with a positive electrode active material 3, an electrolyte 5, and a negative electrode active material 4 in layers, and the periphery section of the terminal boards 1, 2 is sealed with an electric insulating seal body 6. A three-layer film laminated with adhesive films 61 on both faces of a resin film 62 is used for the seal body 6 in a thin battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a sealing portion of a thin battery.

[0002]

2. Description of the Related Art In recent years, portable electronic devices and devices using batteries have been rapidly reduced in size and thickness. As a result, the batteries used as the power source for those electronic devices are also
The demand for smaller and thinner products is increasing. In particular, thin batteries using light metal typified by lithium as the negative electrode active material can be made with a thickness of 0.1 mm, and the thickness of the sealing portion and the current collector has become quite thin, tens of microns. .. As shown in FIG. 3, a conventional sealing method for a thin battery is such that a sealing body 6 made of a single-layer adhesive film is arranged on the peripheral portions of the terminal plates 1 and 2 which also function as current collectors. 1, 2 and sealing body 6
Was heat fused.

[0003]

When the sealing method described in the prior art is used for sealing, since the heat shrinkage rates of the terminal plates 1 and 2 and the sealing body 6 are different, wrinkles remain at the sealing portion as shown in FIG. Remains, stress is applied to the sealing portion during use of the battery,
There is a problem in that a part of the battery opens, and the outside air enters the inside of the battery to deteriorate the battery performance.

The present invention has been made in view of the above problems, and an object thereof is to cause a defect in the sealing portion even if the terminal plates 1 and 2 and the sealing body 6 are sealed by heat fusion. Not to provide a thin battery.

[0005]

In order to achieve the above object, the present invention provides a positive electrode active material 3, an electrolyte 5, and a negative electrode active material 4.
A thin battery in which terminal plates 1 and 2 also functioning as current collectors are arranged above and below a power generation element in which layers and are stacked in layers, and the peripheral edges of the terminal plates 1 and 2 are sealed by an electrically insulating sealing body 6. The sealing body 6 has the adhesive film 6 on both sides of the resin film 62.
It is a three-layer film in which 1 is laminated. The adhesive film 61 is a polyolefin-based thermoplastic resin film having an adhesive function,
The resin film 62 is preferably a film having no functional group having an adhesive function with the polyolefin-based thermoplastic resin film.

[0006]

[Operation] The heat shrinkage of the resin film forming the intermediate layer of the three-layer film is smaller than the heat shrinkage of the adhesive film on both sides of it, and is close to that of the terminal board. It is possible to reduce the wrinkles formed when heat-sealing is performed as compared with the case of the adhesive film single layer. When the three-layer film has the structure according to the second aspect, since the main structures of the adhesive film and the resin film are the same, they are melt-bonded and can be tightly bonded. Further, when the main chain structure of the adhesive film and the resin film is a polyolefin type, the water vapor transmission rate is low, and it is possible to prevent water vapor from mixing into the inside of the battery.

[0007]

An embodiment of the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 is a perspective view of a battery according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA 'in FIG. Here, 1 is a positive electrode terminal plate, 2 is a negative electrode terminal plate, 3 is a positive electrode active material, 4 is a negative electrode active material, 5 is an electrolyte, and 6 is a sealing body.

The sealing body 6 has a three-layer film structure in which an adhesive film 61 is layered on both sides of a resin film 62, and as the resin film 62, a film having no functional group and having a function of adhering a polyolefin thermoplastic resin film. And a polypropylene film obtained by graft-polymerizing maleic anhydride is used as the adhesive film 61. The positive electrode active material 3 contains manganese dioxide as a main component, and the electrolyte 5 is a solid polymer electrolyte obtained by adding lithium perchlorate to polyethylene oxide. Lithium is used as the negative electrode active material 4.

A positive electrode terminal plate 1 and a negative electrode terminal plate 2 made of stainless steel are arranged above and below the power generating element, and the sealing body 6 is arranged between the peripheral portions of the terminal plate 1, 2 and the sealing body 6. And are heat-sealed and sealed. This battery of the present invention is referred to as battery A.

(Comparative Example) A conventional battery in which the sealing body 6 in the above-mentioned embodiment is composed of a single layer of a polypropylene film graft-polymerized with maleic anhydride is referred to as a B battery. The above A and B batteries of 0.2 Ah were discharged with a constant current of 20 mA,
The discharge capacity was investigated for each of the initial discharge and the discharge after storage at 60 ° C. for 20 days. The result of the A battery is shown in FIG. 4, and the result of the B battery is shown in FIG. As shown in FIG. 4, the capacity of the A battery of the present invention hardly decreased even after the high temperature storage, but the discharge capacity of the conventional B battery after the high temperature storage decreased to about 70% of the initial discharge capacity from the FIG. I found out.

[0011]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, the problem of residual stress at the adhesive interface of the sealing portion is eliminated, and a thin battery with long life and high reliability can be provided. Further, by adopting the configuration of claim 2, it is possible to strengthen the adhesion of the sealing portion, prevent mixing of water vapor, etc., and provide a thin battery having a long life and high reliability.

[Brief description of drawings]

FIG. 1 is an external perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view taken along the line A-A ′ of FIG.

FIG. 3 is a cross-sectional view of a conventional battery.

FIG. 4 is a discharge characteristic diagram of a battery of the present invention A.

FIG. 5 is a discharge characteristic diagram of a conventional B battery.

[Explanation of symbols]

 1, 2 Terminal plate 3 Positive electrode active material 4 Negative electrode active material 5 Electrolyte 6 Sealing body 61 Adhesive film 62 Resin film

Claims (2)

[Claims] 1. Terminal plates (1, 2), which also function as current collectors, are arranged above and below a power generating element in which a positive electrode active material (3), an electrolyte (5) and a negative electrode active material (4) are stacked in layers. The terminal board (1,
A thin battery in which the peripheral portion of 2) is sealed by an electrically insulating sealing body (6), wherein the sealing body (6) has an adhesive film (61) laminated on both sides of a resin film (62). A thin battery, which is a three-layer film. 2. The adhesive film (61) is a polyolefin-based thermoplastic resin film having an adhesive function, and the resin film (62) has a functional group having an adhesive function of the polyolefin-based thermoplastic resin film. The thin battery according to claim 1, which is a polyolefin-based thermoplastic resin film removed.