JPH01260755A - Flat type battery - Google Patents

Abstract

PURPOSE:To prevent electrical continuity with a metal base and short circuit and to also prevent electrolyte leakage caused by the bending of a device by covering the whole surfaces, except for the contact parts with outer terminals, of positive and negative terminals with an insulating film comprising a 5-15mum thick adhesive polyester film. CONSTITUTION:The whole surfaces, except for the contact parts with outer terminals, of positive and negative terminals 37, 36 are covered with an insulating film 38 comprising a 5mum thick adhesive polyester film (the thickness of a polyester film is 2.5mum and that of an adhesive is 2.5mum). The insulating film 38 is formed in such a way that the adhesive polyester film is cut in 30mmX50mm, and it is bonded to the whole surfaces of the positive and negative terminals 37, 36, then the contact parts with the outer terminals are cut out with a cutter. The electrical continuity with a metal base which is used to increase mechanical strength and short circuit are prevented, and electrolyte leakage caused by the bending of a device is also prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a flat battery.

[Prior Art] In recent years, as electronic devices such as electronic desktop calculators and electronic wristwatches have become smaller and thinner, there has been an increasing demand for the development of extremely thin flat batteries.

In particular, ultra-thin batteries with a thickness of 1 m14 or less are desired as power supplies for card-type electronic devices such as card-type calculators and IC cards.

By the way, as the above-mentioned flat battery, for example, a flat battery 1 having a structure shown in FIG. 3 has been proposed. That is, the third
In the flat battery 1 shown in the figure, a negative electrode sheet 2 and a positive electrode mixture sheet 3 are laminated with a separator 4 in between to form a power generation unit. In the power generation unit made of this laminate, a frame-shaped insulating sealing body 5 is arranged so as to surround the unit. A negative electrode terminal plate 6 is provided on one frame-shaped surface of the insulating sealing body 5 and on the lower surface of the negative electrode sheet 2.
A positive electrode terminal plate 7 is formed in close contact with the other frame-shaped surface of the frame-shaped surface and the upper surface of the positive electrode mixture sheet 3 via, for example, an adhesive, and the above-mentioned power generation The unit is sealed.

Figure 4 shows how the flat battery l described above is used in a card-type electronic device (
FIG. 3 is a vertical cross-sectional view showing a state where the device is built into an IC card (for example, an IC card). That is, numeral 11 in the figure is a circuit sheet on which the flat battery 1 and other elements (for example, an integrated circuit chip, not shown) are mounted. This circuit sheet 11 is sandwiched between plastic sheets 12a and 12b made of vinyl chloride resin or the like. These plastic sheets 12a,
12b constitutes a card as a whole depending on whether it is adhered to the circuit sheet 11 with an adhesive or its peripheral portion is heat-sealed. The positive and negative terminals 7.6 of the flat battery l built in the plastic sheet 12a 512b and the circuit chip on the circuit sheet 11 are as follows:
They are electrically connected by elastic lead terminals 13 and 14, respectively. The positive and negative terminals 7.6 and lead terminals 1
3.14 electrical connections are made using welding or conductive tape. Note that such IC cards are bent under stress during transportation or use, and there is a risk that the integrated circuits and other elements inside the card may lose their functions. A base body 15 made of a thin metal plate is inserted into the card to increase its strength, thereby preventing the card from curving as much as possible. In addition, for the purpose of further increasing reliability, plastic sheets 12a and 12b are used.
The space surrounded by the flat battery 11, circuit sheet 11, and other elements and parts is filled with an adhesive made of synthetic resin (not shown). The adhesive filled in this way improves mechanical strength against bending, etc., and also prevents the built-in flat battery 1 from shifting and prevents the flat battery 1 from coming into contact with the circuit sheet 11 or the metal substrate 15. This prevents external short circuits from occurring.

However, when manufacturing the above-mentioned IC card, a certain thickness (for example, 0.76JII, IC card I
SO standard) plastic sheet 12a,
After filling the space surrounded by 12b with an adhesive made of synthetic resin, the adhesive is cured while being pressurized, so that the positive terminal plate 7 of the flat battery 1 comes into contact with the metal base 15 and becomes electrically conductive. Ru. The metal base I5 is also in contact with the circuit sheet 11, and when the IC card is bent or partially pressurized, the circuit sheet 11 and the metal base 15
There may be electrical continuity between the in this case,
If the opposite pole to the positive terminal plate 7 with which the metal base 15 is in contact is located on the circuit sheet 11, a short circuit will occur at this location and the IC card will not operate. Also,
Even if the metal base 15 is protected with an insulating coating, if it is repeatedly bent, the edge of the positive terminal plate 7 of the flat battery l will break the coating, causing a short circuit as described above and causing the IC card to operate. I don't do it anymore.

On the other hand, a flat type battery having a structure shown in FIG. 5 (Japanese Patent Laid-Open No. 81-258559) is known. This flat battery has a negative electrode sheet 21. A frame-shaped insulating sealing body 24 is disposed so as to surround the power generation unit in which the separator 22 and the positive electrode mixture sheet 23 are laminated, and the insulating sealing body 2
A negative terminal plate 25 and a positive terminal plate 2B are attached to the frame-shaped surfaces on both sides of 4.
For example, the positive and negative electrode terminal plates 2B and 25, excluding the insulating sealing body 24, are covered with resin thin films 27a and 27b in order to further increase the strength against partial pressure.

However, when the flat battery shown in FIG. 5 is incorporated into the above-mentioned card-type electronic device (IC card),
As described above, there was a problem in that the exposed portion of the positive electrode terminal plate 26 above the insulating sealing body 24, which is not covered, comes into contact with the metal base 15, causing an external short circuit. In addition, in the flat battery, it is necessary to align and attach polyester films coated with adhesive to the surface of each terminal board except for the sealing part, which makes the battery assembly process complicated. was there. Furthermore, when the stress is applied to the flat type battery shown in FIG. 5 built into the device due to bending when the IC card is used, the electrolyte inside the battery is damaged by the positive and negative terminal plates 2B and 25 and the insulating sealing body. There was a risk of leakage from the adhesive surface with 24.

The present invention was made in order to solve the conventional problems, and prevents electrical conduction and short circuit with a metal substrate used for the purpose of improving the strength of thin electronic devices after being incorporated into the devices. It is an object of the present invention to provide a highly reliable flat battery that can be easily assembled, is capable of preventing electrolyte leakage due to bending of the device, and is easy to assemble.

[Means for Solving the Problems] The present invention provides a laminate in which a positive electrode mixture sheet, a separator, and a negative electrode sheet are laminated in this order, a frame-shaped insulating sealing body surrounding the laminate, and the positive electrode. Consisting of a positive terminal plate that covers the surface of the mixture sheet and the end face of the insulating sealing body and comes into close contact therewith, and a negative terminal plate that covers the surface of the negative electrode sheet and the other end face of the insulating sealing body and comes in close contact with them. A flat battery, characterized in that the outer surface of the positive and negative terminal plates except for the connecting portions with external terminals is coated with an insulating coating made of an adhesive-coated polyester film having a thickness of 5 to 15 μm. be.

The above-mentioned adhesive-coated polyester film covers the outer surface of the positive and negative terminal plates except for the connecting parts with external terminals, but if each terminal plate has lead terminals extending outward, The surface of each terminal board other than the lead terminals may be coated with an adhesive-coated polyester film.

The reason for limiting the thickness of the above-mentioned adhesive-coated polyester film is that if the thickness is less than 5 μm, the insulation properties will be lowered due to insufficient strength, and it will also be a problem in terms of handling. If it exceeds 15 μm, the total thickness of the battery itself becomes thicker, and in order to make it thin enough to be built into a thin electronic device, the internal power generation unit needs to be made thinner, which reduces the discharge capacity. be.

[Function] According to the present invention, by coating the outer surface of the positive and negative terminal plates, excluding the connection portions with external terminals, with an insulating coating made of an adhesive-coated polyester film having a specific thickness, thin electronic devices can be manufactured. The insulating coating can prevent short circuits by preventing electrical conduction with a metal substrate used for the purpose of improving the strength of the device after it has been incorporated into the device. In addition, if stress due to the bending of the thin electronic device is applied to the battery built into the device, most of the outer surface of the battery except for the connection part with the external terminal is coated with an insulating coating. It is possible to prevent the electrolyte inside the battery from leaking from the interface between the positive and negative terminal plates and the insulating sealing body. Furthermore, by using an adhesive-coated polyester film with a specific thickness as an insulating coating, external terminals can be formed on the outer surface of the battery without having to perform complicated operations unlike the conventional flat battery shown in FIG. Most of the parts except for the connecting parts can be coated with an insulating film, which significantly improves assembly work. Moreover, the insulating film that is coated can be formed as a film that does not generate bubbles and has high insulation reliability, unlike a film that is formed by a coating method.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail with reference to FIG.

Example 1 In a flat battery 31 shown in FIG. 1, a negative electrode sheet 32 made of lithium and a positive electrode mixture sheet 33 made of a mixture of manganese dioxide, graphite, and polytetrafluoroethylene are laminated with a separator 34 in between to form a power generation unit. is forming. In the power generation unit made of this laminate, a frame-shaped insulating sealing body 35 made of, for example, an ionomer resin is disposed to surround the unit. A stainless steel negative electrode terminal plate 36 of 20cm x 40ru 20ai+ x 40 on the top surface of the agent sheet 33
A positive electrode terminal plate 37 made of stainless steel of uXO, 05an is formed in close contact with, for example, an adhesive, and the power generation unit is sealed by the frame-shaped insulating sealing body 35 and the positive and negative electrode terminal plates 37 and 36. And the positive and negative terminal plates 37.3
5μ thick on the entire outer surface except for the connection part with external terminal 6.
An insulating coating 38 made of a polyester adhesive film (thickness of the polyester film: 2.5 μm, thickness of the adhesive layer: 2.5 μm) is coated thereon. This insulation coating 38
The above polyester adhesive film was 30an
Cut it out to a size of 50IllJI and attach it to the positive and negative terminal plate 3.
7.36 was adhered to the entire outer surface, and the connection portion with the external terminal was cut off with a cutter.

Example 2 A polyester adhesive film with a thickness of 15 μm was applied to the entire outer surface of the positive and negative terminal plates except for the connection portions with external terminals (thickness of polyester film: 10 μm; thickness of adhesive layer: 5 μm).
) A flat battery similar to that of Example 1 was assembled except that it was coated with an insulating film 38 consisting of:

Therefore, the flat battery 3I of Example 1.2 was mounted on a thin electronic device (IC card) shown in FIG.
With the positive and negative terminal plates 37.3B connected to the lead terminals 14.13 as external terminals, the radius of curvature is 150.
Step 1 is to bend the thin electronic device by pressing it against the H cylinder.
I checked the operation ten thousand times. The IC card shown in FIG. 2 has the same structure as that shown in FIG. 4 described above except for the flat battery 31 mounted thereon. The operation check was performed on 10 IC cards, and if even one of them had malfunction, it was judged as unacceptable. Further, after the IC card was repeatedly bent, the discharge capacity of the flat battery built into the card was measured. These results are shown in Table 1 below.

In Table 1, as a comparative example, the results of the bending test for an IC card containing a flat battery not covered with an insulating thin film and the discharge capacity of the flat battery are also listed.

Table 1 As is clear from Table 1 above, the entire outer surface of the positive and negative terminal plates, excluding the connection areas with external terminals, has a thickness of 5 μm and 15 μm.
The IC card containing the flat battery of Example 1.2 coated with an insulating film made of a polyester adhesive film showed no abnormality in operation even after 10,000 bending tests, and had a good discharge capacity. It can be seen that it has

[Effects of the Invention] As detailed above, according to the present invention, it is possible to prevent electrical conduction and short circuits with a metal substrate used for the purpose of improving the strength of a thin electronic device after it is incorporated into the device. Furthermore, it is possible to provide a highly reliable flat battery that can prevent electrolyte leakage due to bending of the device, and is easy to assemble.

4. r1! Brief explanation of J-plane FIG. 1 is a cross-sectional view of a flat battery showing an embodiment of the present invention.
Figure 2 is a cross-sectional view showing an IC card incorporating the flat battery shown in Figure 1, Figure 3 is a cross-sectional view showing a conventional flat battery, and Figure 4 is a cross-sectional view showing the IC card incorporating the flat battery shown in Figure 3. FIG. 5 is a sectional view showing another conventional flat battery.

11... Circuit sheet, 12a% 12b... Resin sheet, 13.14... Lead terminal (external terminal), 15.
...Metal base, 31... Flat battery, 32... Negative electrode sheet, 33... Positive electrode mixture sheet, 34... Separator, 35... Frame-shaped insulating sealing body, 36... Negative electrode Terminal plate, 37... Positive terminal plate, 38... Insulating coating.

Applicant's agent: Patent attorney Takehiko Suzue

Claims (1)

[Claims] A laminate in which a positive electrode mixture sheet, a separator, and a negative electrode sheet are laminated in this order, a frame-shaped insulating sealing body surrounding the laminate, and a surface of the positive electrode mixture sheet and an end face of the insulating sealing body. a positive terminal plate that covers and comes into close contact with these;
In a flat battery consisting of a negative electrode terminal plate that covers the surface of the negative electrode sheet and the other end face of the insulating sealing body and is in close contact with these, the outer surface of the positive and negative electrode terminal plates except for the connecting portions with the external terminals has a thickness of 5 mm. A flat battery characterized by being coated with an insulating coating made of an adhesive-coated polyester film of ~15 μm.