JPH06302305A - Flat battery - Google Patents

Abstract

PURPOSE:To prevent any short circuit taking place by opposed collectors making contact with each other at bonding and prevent wrinkles and warps so as to improve adhesive strength by sealing the of a sheet-shaped terminal board with a seat material having heat-sealing adhesive layers on both faces of an inorganic material. CONSTITUTION:A positive electrode 3 and a negative electrode 4 are so arranged as to face each other through a separator 5 between two sheets of sheet-shaped positive negative terminal boards 1 and 2 serving also as the collectors of a positive pole and a negative pole. The margin of the sheet-shaped terminal board is sealed with a seal material 6 having heat-sealing adhesive layers on both faces of an inorganic material. Thermofusing resin is used for the adhesive layer. The thickness of the seal material 6 is 5-50mum, and the thickness of the inorganic material is 5-500mum. For example, for the seal material 6, an object where transformed polyolefine 6'', of 30mum is stacked on both sides of the core material of an Al box 6' of 25mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat battery, and more particularly to sealing of peripheral edges of two sheet-shaped positive and negative electrode terminal plates.

[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. Along with this, demands for downsizing and thinning of batteries used as power sources of such electronic devices are increasing. In particular, flat batteries with a thickness of 0.5 mm or less, which uses a light metal represented by lithium as the negative electrode active material, can be used as a power source to be built into card-shaped devices such as IC cards. And a sealant that withstands long-term use is required. Conventionally, as a sealing material used for a flat battery, various modified polyolefin resins for sealing by thermal fusion bonding and their copolymers have been proposed and used.

[0003]

However, in the case of using the heat-fusible resin which has been conventionally used, it is necessary to have high wettability and flowability at the time of melting in order to exhibit good adhesiveness. However, in this case, there is a problem that the resin starts to flow at the time of adhesion and the current collectors facing each other come into contact with each other to cause a short circuit. In addition, in the resin film, thermal contraction occurs due to relaxation at a temperature equal to or higher than the glass transition point, which causes wrinkles and warpage in the current collector as an adherend. In addition, since the coefficient of thermal expansion greatly differs from that of the current collector as the adherend in the process of solidifying from the molten state, there is a problem that wrinkles and warpage are generated by the seal.

The present invention has been made to solve the above-mentioned problems, and prevents a short circuit caused by the contact between the current collectors facing each other at the time of bonding, does not cause wrinkles or warpage, and is a seal excellent in bonding strength. An object of the present invention is to provide a flat battery having a material.

[0005]

In order to achieve the above object, the present invention is designed so that two sheet-like positive and negative electrode terminal plates which also serve as a current collector for a positive electrode and a negative electrode terminal plate are opposed to each other via a separator. A positive electrode and a negative electrode were arranged, and the peripheral portion of the sheet-shaped terminal plate was sealed with a sealing material having a heat-sealing adhesive layer on both sides of an inorganic substance.

As the inorganic substance to be used, various ceramic substances, metals and the like can be mentioned, but it is preferable to use a metal in terms of flexibility and flexibility, and as the metal,
Various alloys other than aluminum, gold, silver, copper, stainless steel, nickel, etc. are used.

[0007] More preferably, aluminum is preferably used because it has a high electric potential resistance, there is no fear of elution even if it comes into contact with an electrolytic solution, and it is inexpensive.

Further, in order to improve the adhesiveness between the sheet-like terminal plate and the adhesive layer, the terminal plate may be subjected to surface treatment such as oxidation treatment, etching treatment and chromate treatment, or as a single body. Alternatively, it may be a laminated body.

In the heat-sealable adhesive layer of the sealing material, various heat-fusible resins having good adhesive performance to the inorganic substance and the positive and negative electrode terminal plates are used. Examples thereof include modified polyolefins, copolymers thereof, polyamide resins, polyvinylidene chloride resins, polyvinylidene fluoride resins, and various copolymers of these resins. Moreover, these can be used by blending or laminating as needed. An adhesive may be used between the layers in some cases.

[0010]

The thickness of the sealing material used depends on the thickness of the battery to be produced, but when a thickness of 15 to 900 μm is used, the thickness of the heat-sealable adhesive layer is 5 to 50.
The thickness of the inorganic material layer is 0 μm, and the thickness of the inorganic material layer is 5 to 500 μm. If the thickness of the inorganic material layer is too thick compared to the heat-sealable adhesive layer, it may lead to a decrease in flexibility and the risk of short circuit, and if it is too thin, the heat-sealable resin flows out, and the effect of the present invention is expressed. do not do. The sealing material can be used either as a single layer or as a laminate.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a stainless steel positive electrode terminal plate that also serves as a positive electrode current collector, 2 is a stainless steel negative electrode terminal plate that also serves as a negative electrode current collector, and 3 is a positive electrode containing manganese dioxide as a main component. Mixture 4 is a negative electrode made of lithium, 5 is a polypropylene non-woven fabric impregnated with a propylene carbonate solution of lithium perchlorate, 6 is a sealing material according to the present invention, and 25 μm of aluminum is used as a core material and 30 μm is provided on both surfaces thereof. It is a laminate of modified polyolefins of.

As a result, the flow at the time of bonding is reduced,
As a result, there was no warp or wrinkle, and a good adhesion state without short circuit was obtained. As a result of analysis with a thermomechanical analyzer (TMA), the coefficient of thermal expansion was restricted to aluminum, and the shrinkage of the resin film caused by relaxation during heating was significantly improved.

(Comparative Example 1) A thin battery was prepared in the same manner as in the example except that a modified polyolefin of 80 μm was used as the sealing material. Half of the manufactured batteries were short-circuited.

Comparative Example 2 A thin battery was produced in the same manner as in Example except that 70 μm of aluminum was used as a core material and 4 μm of modified polyolefin was laminated on both sides of the core material as a sealing material. All the produced batteries were short-circuited.

The above results are summarized in Table 1.

[0016]

As described above, according to the present invention, it is possible to provide a flat battery which is excellent in flexibility and airtightness and has a small defect rate during manufacturing without appearance defects such as wrinkles and warpage. Further, the present invention is particularly effective for thin batteries, but is not limited to this.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a thin battery using a sealing material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Positive electrode terminal plate 2 Negative electrode terminal plate 3 Positive electrode mixture 4 Negative electrode 5 Separator 6 Sealing material 6'Metallic aluminum foil 6 "Hot melt adhesive layer

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Yutaka Horibe, 6-6 Josaimachi, Takatsuki City, Osaka Prefecture Yuasa Corporation, Inc. (72) Kazushige Takeda 6-6, Josaimachi, Takatsuki City, Osaka Prefecture Inside Yuasa Corporation

Claims (4)

[Claims] 1. A double collector serving as a positive electrode and a negative electrode, respectively.
The sheet-shaped terminal plates have flat power generating elements facing each other via a separator, and a heat-sealing frame-shaped insulating member is sandwiched on the inner surface of the peripheral edge of the sheet-shaped terminal plate, and the power generating element is formed by heat fusion. In a thin battery with sealed
A flat battery, wherein the heat-sealable frame-shaped insulating member has a heat-sealable adhesive layer on both surfaces of an inorganic substance. 2. The flat battery according to claim 1, wherein the inorganic substance is a metal. 3. The flat battery according to claim 1, wherein the inorganic substance is aluminum. 4. The inorganic material layer has a thickness of 5 to 800 μm.
2. The flat battery according to claim 1, wherein the heat-sealable adhesive layer has a thickness of 5 to 500 μm.