JPH01320753A - Manufacture of thin battery - Google Patents

Abstract

PURPOSE:To obtain a thin battery without causing total height fault by heating heat fusing resin by the specified process using a pressuring jig consisting of a resistor so as to perform fusion sealing. CONSTITUTION:Thermofusing resin 4a in the form of a thin circular sheet is fused in advance to the periphery of a shallow metallic plate 1 on the negative electrode side in the form of a vessel whose periphery is brim shape, and a generation element 3 is charged at the center of the metallic plate 1 on this negative electrode side, and this is placed on a stage 5. A recess 5a is formed at the center of the stage 5, and the part projected downward of the metal plate 1 on the negative electrode is stored in the recess 5a. Next, a flat metallic plate 2 to the periphery of which thermofusing resin 4b made in the form of a circular sheet is fused in advance is placed on the metallic plate 1 on the stage 5 such that the resins 4a and 4b abut on each other, and the upper side of the battery is covered with a heat resistant resin film 6 to the periphery of which pressure sensitive adhesive 7 is applied, and the periphery of the film 6 is fixed to the stage 5 by the pressure sensitive adhesive 7, and the air in the space covered with the film is sucked by a vacuum pump.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thin type device having a structure in which a power generating element is loaded between two metal plates arranged facing each other, and the peripheral edges of both metal plates are used as a sealing part. This invention relates to a battery manufacturing method.

[Conventional technology]

For button-shaped and coin-shaped batteries, a sealing method is used in which two metal cans that make up the positive and negative collectors are fitted together, and the peripheral edges of both metal cans are bent and tightened with a synthetic resin backing in between. It has been widely used.

However, as electronic devices have become smaller, lighter, and thinner in recent years, the total height of the batteries used in these devices has increased by 1.
There is a growing demand for thinner products, such as less than 0.5 mm, and even less than 0.5 mm, but the aforementioned sealing method that utilizes the bending of metal cans has limitations in terms of processing technology. I was unable to comply with your request.

Therefore, two flat metal plates are arranged facing each other and joined with a spacer interposed between their peripheral edges, or the center part of one or both of the two metal plates is made to protrude outward. In other words, a sealing method has been proposed in which two metal plates are formed into a shallow container shape with a brim-like peripheral edge, and these two metal plates are placed facing each other and joined at the peripheral edge. 62-55865).

A heat-fusible resin called hot-melt adhesive is generally used to bond these together, but since this heat-fusible resin can be handled as a solid part formed into a sheet, it can be used for sealing. It has excellent properties such as being easy to use, and unlike solution-type adhesives, there is no risk of it flowing into the battery and mixing with the electrolyte, degrading battery performance.

By the way, the method that was first adopted as the sealing method using the above-mentioned heat-fusible resin was a heat-fusible method in which a heat block was used to press the sealing part between the sealing parts. The resin is heated and melted, and then the pressure is continued until the resin is cooled and solidified to seal the resin. Therefore,
The power generation element loaded between the metal plates is affected by heat due to the long heating period until it cools down, resulting in a decrease in battery performance, and the problem is that productivity is poor because it takes time to seal. .

Therefore, the present inventors used a pressure jig made of a resistor as a heating means, and generated heat by applying electricity to the jig while pressurizing the sealing part with the jig. have developed a method of fusion-sealing by heating a heat-fusible resin (for example, Japanese Patent Laid-Open No. 62-219459).

According to this method, the required amount of thermal energy can be quickly obtained by energizing the pressurizing jig, and it can be quickly cooled by removing the energization, so that heat is not transferred to the power generation element. There is an advantage that the influence can be reduced and the deterioration of battery performance can be reduced.

[Problem to be solved by the invention]

However, even with the above-mentioned sealing method, there is a problem in that the battery is sealed with air trapped inside it, causing the battery to swell and resulting in a defective overall height of the battery. In addition, due to the above-mentioned battery sagging, the closeness between the metal plate that also serves as a current collector and the positive and negative electrodes becomes poor, increasing internal resistance and lowering the open circuit voltage. This was also a cause of performance deterioration.

Therefore, the present invention provides a method for manufacturing a thin battery that prevents sealing with gas such as air trapped inside the battery and without causing total height defects. The purpose is to beg.

[Means for Solving the Problems] □ The present invention uses a pressure jig made of a resistor as a heating means, covers the top surface of the battery with a heat-resistant resin film, and wraps the periphery of the heat-resistant resin film around the battery. is fixed to the stage on which the heat-resistant resin film is placed, and the gas in the space covered with the heat-resistant resin film is sucked out, and the sealing part is pressurized with a pressure jig through the heat-resistant resin film to apply the pressure. The above object is achieved by applying electricity to the jig to heat the heat-fusible resin present in the sealing part and sealing by fusion.

That is, according to the above method, the battery is covered with a heat-resistant resin film, and while the gas in the space covered with the heat-resistant resin film is sucked, the heat-fusible resin is heated and sealed. Gas is not trapped in the battery, so battery bulges do not occur, and battery total height defects are prevented.

The advantage of using a pressurizing jig made of a resistor as a heating means is that it is possible to quickly obtain the required amount of thermal energy and to quickly cool it down, so heating with a heat block The advantages of less thermal influence on the power generating element and less deterioration of battery performance are also retained compared to methods.

In implementing the present invention, for example, a polytetrafluoroethylene film, a polyimide film, or the like is used as the heat-resistant resin film that covers the top surface of the battery.

In addition, the gas in the space covered with the heat-resistant resin film may be suctioned by, for example, a vacuum pump, and this suction is continued until the heat-fusible resin is fused by heating.
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〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

First, as shown in Figure 2, the negative electrode side has a central part that protrudes outward (the outside side refers to the outer side in the direction of the thickness of the battery, and in the state shown in Figure 2, the lower side). A heat-fusible resin 4a formed into a thin annular sheet is fused in advance to the periphery of the metal plate 1, which is shaped like a shallow container with a brim around the periphery on the negative electrode side. , the power generating element 3 is loaded into the center part of the metal plate 1 on the negative electrode side (this center part protrudes toward the bottom side, so it has a concave shape in the state shown in FIG. 2). It was placed on stage 5.

A fourth part 5a is formed in the center of the stage 5, and the center part of the metal plate 1 on the negative electrode side, that is, the part protruding toward the lower side, is inserted into the recess 5a with a space between it and the bottom part. The peripheral portion of the metal plate 1 is placed in the peripheral portion of the recess 5a.

Next, a flat metal plate 2 is attached to the negative electrode side metal plate 1 on the stage 5, and a heat-fusible resin 4b formed in an annular seal shape is pre-fused to the peripheral edge. It was placed so that the heat-fusible resins 4a and 4b were in contact with each other.

Next, as shown in FIG. 1, the top surface of the battery is covered with a heat-resistant resin film 6 whose periphery has been coated with an adhesive 7, and the periphery of the heat-resistant resin film 6 is attached to a stage 5 using an adhesive 7. The stage 5 was fixed, and the gas in the space covered with the heat-resistant resin film 6 was sucked through the opening 5b provided in the recess 5a of the stage 5 using a vacuum pump.

In this state, a pressure jig 8 made of a resistor is placed on the heat-resistant resin film 6, and pressurizes the sealing portion, that is, the peripheral edge of both metal plates 1.2, through the heat-resistant resin film 6. Under this pressure, a pulse-controlled current (20
0V, IOA, 10 seconds) was applied to heat-seal the heat-fusible resins 4a and 4b present in the sealing portion.

Thereafter, the power to the pressurizing jig 8 was removed, and cooled argon gas was blown onto the side surface of the pressurizing jig 8 from the ventilation holes 9 and 9' to perform forced cooling. After the heat-fusible resin was cooled and solidified, the pressure was released, suction was stopped, and the sealing work was completed when the pressure reached atmospheric pressure. The pressure jig 8 and the ventilation holes 9 and 9' were moved in one direction, the heat-resistant resin film 6 was peeled off from the stage 5, and the battery was taken out from the stage 5. FIG. 3 shows the battery after this sealing is completed.

In the battery shown in the third circle, 4 is a heat-fusible resin;
This heat-fusible resin 4 is a heat-fusible resin 4a, 4b that has been pre-fused to the peripheral edge of each metal plate 1.2.
is fused by the above sealing operation.

The power generation element 3 consists of a negative electrode, a positive electrode, an electrolyte, and a separator, and the negative electrode has a thickness of 0 at the center of the metal plate 1 on the negative electrode side.
．． At 0511m, rectangular 1,000 aluminum strips measuring 7 mm long and 25 mm wide were laminated and pressed together with lithium strips of the same size, and electrochemically alloyed in the presence of an electrolyte in the battery to form a lithium-aluminum alloy. That is.

Electrolyte Li B (Cbl(5)-・3DME27
．． 8% by weight, propylene carbonate 1-59.1% by weight
It is a gel electrolyte consisting of a mixture of 113.1% and polymethyl methacrylate, and is applied to the separator. In addition, L i B constituting the above gel electrolyte
DME of (C6Hs)4.3 DME is 1,2-dimethoxyethane, and L i B(C6H5)4.3D
ME is a solvate of 1 mole of L i B(C6Hs)a and 3 moles of 1,2-dimethoxyethane. The positive electrode has a weight ratio of titanium disulfide (TiS2) and the gel electrolyte of 5.
It consists of a 0:50 mixture. Note that, unlike the above example, this positive electrode may be formed by coating the central part of the metal plate 2 on the positive electrode side.

The metal plate 1 on the negative electrode side has a thickness of 0.05 mm, T: 16 mm in length,
As mentioned above, the metal plate 2 on the positive electrode side is a stainless steel plate with a width of 34 mm and a length of 15.5 mm with a thickness of 0.03 mm.
A flat stainless steel plate with a width of 33.5 mm is used.

The heat-fusible resin 4 is a modified polyolefin-based heat-fusible resin manufactured by Mitsubishi Yuka Co., Ltd. (product name: MOIIIC1l-300).
) is used, and as the heat-resistant resin film 6, a polytetrafluoroethylene film is used. Also,
A polyimide film or the like may be used as the heat-resistant resin film 6.

The pressure jig 8 has a structure as shown in FIG. 4, and is made of a resistive material such as tungsten alloy, copper tungsten alloy, molybdenum/molybdenum carbide sintered body, or copper chromium alloy, and is pulsed as described above. It is used as a heating member by passing a controlled current through it to generate heat.

As shown in FIG. 4, the pressurizing jig 8 has a rectangular annular pressurizing surface, but FIG. 1 only shows its longitudinal section.

The following Table 1 shows the battery A manufactured by the method of the present invention.
Battery B was manufactured using a pressure jig made of a resistor as a heating member as in the case of the present invention, but without covering the top surface of the battery with a heat-resistant resin film or applying vacuum suction.
This shows the battery total height defective incidence rate of battery C that was heated and sealed with a heat block as in the past. The total height of all batteries is set to 0.5 mm, and the total height of the batteries is 0.5 mm due to swelling. ``Those with a total height exceeding 52mm are considered defective, and the battery total height defect incidence rate is 1,000 for each battery.
We are investigating by manufacturing 0 pieces at a time.

Table 1 As shown in Table 1, battery A manufactured according to the present invention had no battery total height defects, but battery C, which was sealed using heating with a heat block, had a 90% failure rate. A battery total height defect occurred. In addition, in battery B, which was manufactured using a pressure jig made of a resistor as a heating member as in the present invention, but without covering the top surface of the battery with a heat-resistant resin film or applying vacuum suction, 50% of the battery A total height defect occurred.

The reason why there was such a large difference in the battery total height failure rate was that in the case of the present invention, gas was not trapped inside the battery during sealing, but in the conventional sealing method, Although there are differences in degree, in both cases gas was trapped inside the battery during sealing, causing the battery to swell.

In the above embodiment, the metal plate 1 on the negative electrode side is a container-shaped one with a flange-like peripheral edge, but instead, the metal plate 2 on the positive electrode side is a container-shaped one with a flange-shaped peripheral edge. Alternatively, both the metal plate 1 on the negative electrode side and the metal plate 2 on the positive electrode side may be container-shaped with rounded rims. Furthermore, both the metal plate 1 on the negative electrode side and the metal plate 2 on the positive electrode side may be formed into a flat plate shape, and a spacer may be interposed between the peripheral edges thereof. Further, the stage 5, the pressing jig 8, etc. can also be modified in various shapes other than those illustrated in the embodiment.

〔Effect of the invention〕

As explained above, in the present invention, when sealing a battery by heating a heat-fusible resin using a pressure jig made of a resistor, the top surface of the battery is covered with a heat-resistant resin film. The periphery of the heat-resistant resin film is fixed to the stage on which the battery is placed, and the gas in the space covered with the heat-resistant resin film is sucked, and then the gas is sucked through the heat-resistant resin film using a pressure jig. By applying pressure to the sealing portion and heating the heat-fusible resin for fusion sealing, it has become possible to manufacture thin batteries without causing overall height defects.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing the main steps in manufacturing a thin battery according to the present invention, and FIG. 2 is a transition to the process shown in FIG. 1 when manufacturing a thin battery according to the present invention FIG. 3 is a longitudinal cross-sectional view showing the state in the previous step. Third
The figure is a longitudinal sectional view showing an example of a thin battery manufactured according to the present invention. FIG. 4 is a perspective view showing a pressure jig and forced cooling means used in carrying out the present invention. 1...Metal plate on the negative electrode side, 2...Metal plate on the positive electrode side,
3... Power generation element, 4, 4a, 4b... Heat fusion resin, 5... Stage, 5b... Hole, 6...
Heat-resistant resin film, 8... Pressure jig Figure 2 ■... Metal plate 2 on the negative electrode side... Metal plate 3 on the positive electrode side... Power generation elements 4a, 4b... Heat fusion resin 5. ...Stage 5b...Opening hole No. 3 Figure 2...Metal plate on the positive electrode side 3...Power generation element 4...Thermofusible resin 8...Pressure jig Figure 4

Claims (1)

[Claims] (1) In a method for manufacturing a thin battery having a structure in which a power generation element is loaded between two metal plates arranged facing each other, and the peripheral edges of both metal plates are used as a sealing part, the power generation element is loaded. Both metal plates are arranged facing each other with a heat-fusible resin interposed in the sealing part, and the upper surfaces thereof are covered with a heat-resistant resin film, and the periphery of the heat-resistant resin film is covered with the battery being assembled. The gas in the space covered with the heat-resistant resin film is sucked through the opening provided in the stage, and the sealed portion is fixed to the stage with a pressure jig made of a resistor through the heat-resistant resin film. 1. A method for manufacturing a thin battery, characterized in that the heat-fusible resin interposed in the sealing portion is heated and fused-sealed by pressurizing the battery and energizing the pressing jig.