JPS60257069A - Thin type cell - Google Patents

Abstract

PURPOSE:To improve liquid-proof performance in a hot and humid atmosphere by applying a sticky sealing agent to both parts of a boundary between a collector plate and an adhesive layer circularly so as to surround a terminal window hole of an armoring film. CONSTITUTION:A sticky sealing agent 3 mainly composed of low molecular weight polyisobutylene is applied circularly to the outer surfacial side of a positive pole collector plate 1 by screen printing. Next, an epoxy resin adhesive is applied to the outer surfacial side of the positive pole collector plate 1 so as to surround a terminal window hole 15 of an outer armoring film 6 for being solidified and forming an epoxy adhesive layer 4. Then, an olefin system hot-melting adhesive layer 5 is interposed between the epoxy adhesive layer 4 and the armoring film 6 for sticking together the positive pole collector plate 1 and the armoring film 6. The adhesiveness between the positive pole collector plate 1 and the sealing agent 3 is extremely high so that even when an electrolyte is permeated into an adhesive interface between the epoxy adhesive layer 4 and the positive pole collector 1, the permeation of the electrolyte is checked at the part of the sealing agent 3 thus to prevent leakage to the side of the terminal window hole 15.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in thin batteries generally referred to as paper batteries or sheet batteries.

As is well known, this type of thin battery consists of an anode current collector plate, an anode active material layer, a separator, and a cathode active material layer.

It has a m-structure in which a flat power generation element in which cathode current collector plates are laminated in order is covered with two exterior films made of plastic.

The exterior film and current collector plate are bonded together via a synthetic resin adhesive. Further, a terminal window hole is formed in the exterior film, and a current collector plate is exposed within the window hole, and becomes a terminal.

In conventional thin batteries of this type, the outer film and the current collector plate are bonded together using an olefin-based or polyamide-based bottle-melt adhesive, an epoxy resin adhesive, or the like.

When a battery with this adhesive structure is stored in a high temperature and high humidity environment such as 60°C and 90% RH, the adhesiveness of the interface between the current collector plate and the adhesive layer gradually deteriorates, and electrolysis occurs on the interface. Liquid penetration was inevitable. If the electrolyte penetrates the interface between the current collector plate and the adhesive layer, will the current collector plate become exposed? The electrolyte will leak from the hole in the terminal window 2. When a gas-permeable exterior film is used, such deterioration of adhesiveness at the adhesive interface is accelerated by water vapor and oxygen penetrating from the outside acting on the adhesive interface.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to simplify the leakage path that passes through the interface between the adhesive layer that adheres the exterior film and the current collector plate and the current collector plate. It is an object of the present invention to provide a thin battery which can be reliably shut off by a suitable means and has improved resistance to wet liquid under high temperature and high humidity conditions.

In order to achieve the above object, the present invention applies an adhesive sealant in an annular manner to the interface between at least one of the current collector plates and the adhesive layer so as to surround the terminal window hole of the outer film. It is characterized by being painted.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

Figure 1 shows a thin alkaline battery to which this invention is applied, which has a length of 45ml1, a width of 25II1m, and a thickness of 2.7+
It is a thin rectangular battery of nm size. This battery has an anode current collector plate 1. Anode active material layer 8. Separator 9. Cathode active material layer 14
．． A flat power generation element in which cathode current collector plates 10 are laminated in order,
Two exterior films 6 and 1 with larger outer diameter dimensions than this
3, a frame-like frame 7 is interposed between the peripheral edges of the exterior films 6 and 13, and the exterior films 6 and 13 are heat-sealed to the frame 7 using an impulse sealer or the like. It has a basic structure with a sealed interior.

A terminal window hole 15 is formed in the center of the exterior film 6,
The anode current collector plate 1 is exposed in this portion.

Similarly, a terminal window hole 16 is formed in the center of the exterior film 13, and the cathode current collector plate 10 is exposed in this portion. The anode current collector plate 1 is made of nickel-plated iron foil, and a conductive paint 2 is applied to the inner surface thereof. The anode active material layer 8 is made of a mixture of manganese dioxide, graphite, etc., and is formed into a compact pellet shape. The cathode active material layer 14 is a gel-like material made of amalgamated zinc powder, sodium polyacrylate, potassium hydroxide solution, etc., the separator 9 is made of vinylon nonwoven fabric, and the cathode current collector plate 13- is made of copper foil. Become.

The exterior film 13 on the cathode side is a laminate film consisting of a polyester layer with a thickness of 12μ, an aluminum foil with a thickness of 9B, a nylon layer with a thickness of 15ッ, and a polyethylene layer with a thickness of 40μ, and is substantially gas-impermeable. It is. The exterior film 13 and the cathode current collector plate 10 are bonded to each other via an A-refine hot melt adhesive layer 12 and an epoxy adhesive layer 11. In other words, an adhesive layer 11 made by applying and solidifying an epoxy adhesive to a thickness of approximately 90 IIJ on the outer surface of the cathode current collector plate 10 is adhered to the exterior film 13 using an olefin-based hot melt adhesive layer 12. There is.

The exterior film 6 on the anode side is a polyester layer 1 with a thickness of 12 seconds. It is a laminate film consisting of a vinylidene chloride-vinyl chloride copolymer layer with a thickness of 40 seconds and a polyethylene layer with a thickness of 5011 JI, and is substantially gas permeable. The exterior film 6 and the anode current collector plate 1 are bonded together via the epoxy adhesive layer 4 and the olefin hotmel adhesive layer 5 as described above, but the anode current collector plate 1 is bonded with epoxy adhesive. An adhesive sealing agent 3, which is an important part of the present invention, is applied to the interface with the agent layer 4.

Regarding the joint part between the anode current collector plate 1 and the exterior film 6,
The assembly procedure will be explained in detail.

First, on the outer surface side of the anode current collector plate 1, about 11
IIl inside width 21+111. A 60 m thick adhesive sealant 3 mainly made of low molecular weight polyisobutylene is applied in a ring shape by screen printing. FIG. 2 shows 1 like this. The coating layer of the rectangular annular adhesive sealant 3 is formed so as to surround the terminal window hole 15 of the exterior film 6 that is bonded to the anode current collector plate 1 . next,
An epoxy resin adhesive is applied to the outer surface of the anode current collector plate 1 to a thickness of about 80 IIJI and solidified to form an epoxy adhesive layer 4. The sealant 3 has semi-fluid adhesiveness, but after the sealant 3 is covered with the epoxy adhesive layer 4 and the epoxy adhesive layer 4 has solidified, the adhesive sealant 3 will flow freely. The applied shape is maintained in the specified shape. Next, an olefin hot melt adhesive layer 5 is interposed between the epoxy adhesive layer 4 and the exterior film 6, and the anode current collector plate 1 and the exterior film 6 are bonded together.

The peripheral edge of the exterior film 6 to which the anode current collector plate 1 is adhered as described above is heat-sealed to the frame 7. Then, on the anode current collector plate 1, an anode active material layer 8. Separators 9 are stacked and electrolyte is poured. Further, as described above, a cathode active material layer 14 coated on the cathode current collector plate 10 adhered to the inner surface of the exterior film 13 is stacked on the separator 9, and the periphery of the exterior film 13 is heat-sealed to the frame 7. do. This completes the thin battery.

The adhesive sealant 3 mainly composed of low molecular weight polyisobutylene is chemically stable, has strong adhesiveness, has electrolyte resistance, and has semi-fluidity over a wide temperature range. This sealant 3 is in close contact with the anode current collector plate 1 at a position surrounding the terminal window hole 15, and its free flow is regulated by the epoxy adhesive layer 4. The adhesion between the anode current collector plate 1 and the sealant 3 is extremely high. Penetration of the liquid is prevented, and leakage of liquid to the terminal window hole 15 side is prevented.

Note that no adhesive sealant is provided at the bonded portion between the cathode current collector plate 10 and the exterior film 13, since a gas-impermeable film is used as the exterior film 13. Since the exterior film 13 is gas impermeable,
No external water vapor or oxygen enters the adhesive layer 11.12,
There is little deterioration of the adhesive interface, and the cathode current collector plate 10 and adhesive layer 11
There is almost no leakage along the interface between the However, the present invention is not limited to such an embodiment, and an adhesive sealant may be provided on the cathode current collector plate side in the same way as on the anode side, or depending on the configuration, an adhesive sealant may be provided only on the cathode side. may be provided.

By the way, the thin alkaline battery of the above-mentioned embodiment is designated as A, and the thin alkaline battery of the conventional structure described at the beginning with the same dimensions is designated as 8. Forty batteries each of Batteries A and B were stored in a high-temperature, high-humidity environment of 60°C and 90% Rl-1, and the electrolyte was leaked from the terminal window hole 15 through the adhesive interface of the anode current collector plate. − Checked for leaking batteries. The results are shown in the table below.

In this way, battery A according to the present invention did not cause any leakage up to 28 days, whereas conventional battery B had no leakage until 28 days.
Half of them leaked by the 8th day.

In addition, in the above embodiment, wA Kyokuto electric board 1 and exterior film 6
Although the epoxy adhesive layer 4 and the olefin hob 1 are melt-bonded, the present invention is not limited to this, and as shown in FIG. The adhesive sealant 3 may be bonded using the heat-sensitive adhesive layer 17, and even in that case, the adhesive sealant 3 can be applied to the surface of the anode current collector plate 1 in the shape of a J that is embedded in the adhesive layer 17.

As explained in detail, this invention prevents liquid leakage from the bond between the current collector plate and the outer film in this type of thin battery from reaching the terminal window hole. This can be prevented by simple means, and a thin battery with an excellent shelf life under high temperature and humidity can be realized.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a thin alkaline battery according to an embodiment of the present invention, FIG. 2 is a diagram showing the shape of the adhesive sealant 3 applied to the same battery, and FIG. 3 is another embodiment of the present invention. FIG. 3 is a cross-sectional view of the bonded portion between the current collector plate and the exterior film. １・・・・・・・・・Anode current collector plate ２・・・・・・・・・
・Conductive paint 3...Adhesive sealant 4...Epoxy adhesive layer 5...
...Olefin hot melt adhesive layer 6...
......Exterior film 8...Anode active material layer 9...Separator 10...
- Cathode current collector plate 11...Epoxy adhesive layer 12...Olefin hot melt adhesive layer 1
3...Exterior film 14...Cathode active material layer 10-15', 16...Terminal window hole 17...Heat-sensitive adhesive patent applicant Fuji Denki Kagaku Co., Ltd. Patent Attorney -Kensuke Shiro11-

Claims (2)

[Claims] (1) A current collector plate is adhered to the inner surface of each of the two exterior films via an adhesive layer, and a thin anode active material layer and a separator are provided between the two current collector plates. A thin battery in which a cathode active material layer is sandwiched, the peripheral edges of both of the exterior films are sealed, and the current collector plates are exposed in terminal window holes formed in both exterior films. a thin type, characterized in that an adhesive sealant is coated in an annular shape on the interface between at least one of the current collector plates and the adhesive layer so as to surround the terminal window holes; battery. (2) The thin battery according to claim 1, wherein the adhesive sealant is mainly composed of polyisobutylene.