JP3289797B2 - Flat battery - Google Patents

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 a peripheral portion of two sheet-like positive / negative terminal plates.

[0002]

2. Description of the Related Art In recent years, portable electronic devices and devices using batteries have been rapidly becoming smaller and thinner. Accordingly, demands for smaller and thinner batteries used as power supplies for these electronic devices have been increasing. In particular, flat batteries with a thickness of 0.5 mm or less, using a light metal represented by lithium as the negative electrode active material, have a small thickness and are flexible enough to withstand bending as a power supply built into card-like devices such as IC cards. There is a demand for a sealing material that can withstand long-term use. Conventionally, as a sealing material used for a flat battery, various kinds of modified polyolefin resins which seal by heat fusion, copolymers thereof, and the like have been proposed and used.

[0003]

However, in the case of using a heat-fusible resin as conventionally used, a material having high wettability and flowability at the time of melting is required in order to exhibit good adhesiveness. However, in this case, there is a problem that the resin starts flowing at the time of bonding, and the current collectors facing each other come into contact with each other to cause a short circuit. Further, in the resin film, thermal shrinkage occurs due to relaxation at a temperature equal to or higher than the glass transition point, which causes wrinkles and warpage of the current collector as an adherend. In addition, during the process of solidification from the molten state, the thermal expansion coefficient is significantly different from that of the current collector as the adherend, so that there is a problem that wrinkles and warpage are generated by the seal.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and prevents a short circuit caused by contact of a current collector facing at the time of bonding, does not generate wrinkles or warpage, and is a seal excellent in bonding strength. It is an object to provide a flat battery having a material.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a structure in which two sheet-like positive and negative electrode terminal plates, which also serve as current collectors for a positive electrode and a negative electrode, face each other with a separator interposed therebetween. The positive electrode and the 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 surfaces of an inorganic substance.

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

[0007] More preferably, aluminum, which has high potential resistance, does not cause elution even when brought into contact with an electrolytic solution, and is inexpensive, is preferably used.

In order to improve the adhesion between the sheet-shaped terminal plate and the adhesive layer, the terminal plate may be subjected to a surface treatment such as an oxidation treatment, an etching treatment and a chromate treatment. Or a laminate.

In the heat-sealable adhesive layer of the sealing material, various kinds of heat-fusible resins having good adhesion performance to inorganic substances and positive and negative electrode terminal plates are used. For example, a modified polyolefin, a copolymer thereof, a polyamide resin, a polyvinylidene chloride resin, a polyvinylidene fluoride resin, and various copolymers of these resins are exemplified. These can be blended or laminated as needed. An adhesive may be used between the layers in some cases.

[0010]

The thickness of the sealing material to be used depends on the thickness of the battery to be produced. For example, when a thickness of 15 to 900 μm is used, the thickness of the heat-sealable adhesive layer is 5 to 50 μm.
A layer having a thickness of 0 μm and an inorganic substance layer having a thickness of 5 to 500 μm is used. If the thickness of the inorganic material layer is too thick compared to the heat-sealable adhesive layer, the flexibility or the risk of short-circuiting is caused.If the thickness is too small, the heat-sealable resin flows out, and the effect of the present invention is exhibited. 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 denotes a stainless steel positive electrode terminal plate serving also as a positive electrode current collector, 2 denotes a stainless steel negative electrode terminal plate serving also as a negative electrode current collector, and 3 denotes a positive electrode mainly composed of manganese dioxide. The mixture, 4 is a negative electrode made of lithium, 5 is a polypropylene nonwoven fabric impregnated with a solution of lithium perchlorate in propylene carbonate, 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 formed on both surfaces thereof. Are laminated.

As a result, the flow during bonding is reduced,
As a result, a good adhesion state without warpage or wrinkles and 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 flat battery was manufactured in the same manner as in the example except that 80 μm of the modified polyolefin was used as a sealing material. Half of the 10 prepared batteries were short-circuited.

Comparative Example 2 70 μm aluminum was used as a core material and 4 μm
A flat battery was produced in the same manner as in the Example except that a laminated product of the modified polyolefin was used as a sealing material. All of the prepared 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 rich in flexibility and airtightness, has no appearance defects such as wrinkles and warpages, and has a small defective rate at the time of manufacture. The present invention is particularly effective for flat batteries, but is not limited thereto.

[Brief description of the drawings]

FIG. 1 is a sectional view of a flat battery using a sealing material of the present invention.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunari Takeda 6-6 Josaicho, Takatsuki-shi, Osaka Examiner, Yuasa Corporation, Inc. Examiner Masahiro Takagi (56) References Japanese Utility Model Showa 61-119262 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 2/02-2/08

Claims (3)

(57) [Claims] 1. A current collector for a positive electrode and a negative electrode
A flat power generating element opposed to a sheet-like terminal plate with a separator interposed therebetween, and a heat-sealing frame-like insulating member sandwiched between inner surfaces of peripheral edge portions of the sheet-like terminal plate; In a flat battery sealed with
The heat-sealing frame-shaped insulating member has a thickness on both sides of the metal.
Has a heat-sealing adhesive layer having a thickness of 5 to 500 μm . 2. The flat battery according to claim 1, wherein the metal is aluminum. 3. The flat battery according to claim 1, wherein the thickness of the metal layer is 5 to 800 μm.