JPS61214353A - Method for sealing thin-type cell - Google Patents

Abstract

PURPOSE:To shorten a time for forming a sealing part by facing collect-plates, with heat-welding materials being included at the sealing part, and pressing them from one face side with a pressing plate made of a material permeated by laser lights and then irradiating laser lights to sealing parts. CONSTITUTION:A ring-shaped spacer 2 of ceramics or the like is fixed at one- side collecting plate 1a with adhesive 3. Next, together with heating and sticking a heat-welding material 4a molded into a ring-shaped sheet on the spacer 2, an electric-generating element 5 is loaded on the collecting plate 1a. Then, the other side collecting plate 1b, on which a heat-welding material molded into a ring-shaped sheet is heated and stuck beforehand, is placed and pressed from above with a pressing plate 7 made of a material permeated by laser lights. After irradiating laser lights 8 to melt heat-welding materials 4a and 4b, cooling and sealing are performed. Therefore, with the time from heating to cooling being largely shortened, productivity of a thin-type cell can be improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a thin battery having a structure in which a power generation element is loaded between two metal plates arranged facing each other, and the periphery of both metal plates is a sealing part. This paper also relates to the sealing method used in the present invention.

[Conventional technology]

In button-type or coin-type batteries, the two metal cans that make up the positive and negative electrode current collector plates are fitted together, and the peripheral edges of both metal cans are bent and tightened with a backing made of an organic polymer material sandwiched between them. Sealing methods are widely used. However, in recent years, electronic devices have become smaller.

As batteries become lighter and thinner, there is a demand for thinner batteries with a total thickness of In1 or less, and even 0.5118 or less.

Since the above-mentioned sealing method has limitations in terms of processing technology when it comes to such thin batteries, two flat metal plates are placed facing each other and a spacer made of ceramic or the like is interposed between the peripheries. Attempts have been made to seal the metal plates by joining them together, or by arranging one or both of the two metal plates in a dish shape to face each other in the same way, and joining them at the periphery. Low melting point solders and adhesives are used for these connections, but heat-sealing materials such as hot-melt adhesives and ceramics that can be hermetically sealed can be handled as solid parts formed into sheet shapes and can be sealed. It is viewed as promising because it is easy to apply, and there is no risk of it flowing into the battery like a paint solution adhesive and mixing with the electrolyte, degrading battery performance (unspecified literature).

[Problem that the invention seeks to solve]

However, the conventional method for sealing thin batteries using the heat-fusible material described above generally involves heating and melting the heat-fusible material inserted into the sealing part while applying pressure with a heat block kept at a high temperature. Afterwards, the pressure described above is continued until the battery is cooled and solidified to seal it by fusion bonding, so the loaded power generating element is affected by heat during the long heating period until cooling, resulting in a decrease in battery performance. Moreover, since it takes time to seal, there is a problem that productivity is poor. On the other hand, in order to avoid this, it is possible to speed up cooling by heating with a heat block and then replacing it with a cool block, but this method results in discontinuous pressurization, resulting in decreased adhesion and distortion of the sealing interface. There were problems in that the sealing strength was insufficient and the operation was complicated.

[Failure to solve the problem]

As a result of intensive studies to solve the above problems, the inventors found that by locally heating the sealing part using laser light, the heat-fusible material can be melted and then cooled and solidified. Compared to using a heat block, the time required to achieve this is significantly shortened, and the heat effect on the power generation elements loaded inside is greatly reduced, making it possible to produce thin batteries with excellent performance and high productivity. They discovered that it could be manufactured based on the original material, and came up with this invention.

That is, the present invention provides a method for sealing a thin battery having a structure in which a power generation element is loaded between two metal plates arranged facing each other, and the periphery of both metal plates is used as a sealing part, in which the power generation element is loaded. In this state, both metal plates are placed facing each other with a heat-adhesive material interposed in the sealing part, and the sealing part is pressurized from one side with a press plate made of a material through which laser light can pass. The present invention relates to a method for sealing a thin battery, characterized in that the heat-fusible material is heated and sealed by irradiating a laser beam onto the sealing portion through the pressing plate.

〔Example〕

Hereinafter, the sealing method of the present invention will be specifically explained with reference to the drawings.

Figures 1 to 4 show two electrodes constituting the positive and negative electrode current collector plates arranged oppositely.
This figure shows the sealing process of a thin battery having a structure in which two metal plates are both flat and a spacer is interposed around the periphery of both metal plates. In this case, first, as shown in FIG. 1, an annular spacer 2 made of ceramic or the like is fixed with adhesive 3 to one side of one metal plate 1a made of stainless steel or the like. As the adhesive 3, in addition to hot melt adhesives and heat-fusible materials such as hermetically sealable ceramics, other adhesives such as paint solution adhesives can be used. As the heating and fusing means, various methods can be adopted, such as local heating using a laser beam, which will be described later, and whole or local heating using a heat block or the like. Then, a heat-fusible material 4a formed into an annular sheet is heat-bonded onto the spacer 2.

Next, as shown in FIG. 2, a power generating element 5 having a known configuration including a positive electrode, a negative electrode, a separator and an electrolyte is loaded inside the spacer 2 of the metal plate 1a, and this is placed on a concave receiving frame 6. do. Then, the other metal plate 1b to which the heat-fusible material 4b formed into an annular sheet has been heat-bonded in advance is placed so that both the heat-fusible materials 4a+4b are in contact with each other.

Subsequently, as shown in FIG. 3, pressure is applied from the other metal plate 1b side using a downwardly convex pressing plate 7 made of a material through which the laser beam can pass, and the laser beam 8 is applied to the metal plate through the pressing plate 7 under heating. Irradiate the peripheral part of 1b, that is, the sealed part, for the required time,
Heat-fusible material 4a.

4b is instantly heated and melted. In this case, since the suppressor 7 itself is not heated and acts as a cool block, the molten heat-fusible material 4 is rapidly cooled and solidified.
Sealing is complete. FIG. 4 shows the thin battery taken out from the receiving frame 6 after this sealing is completed.

5 to 7 show the sealing process of a thin battery having a structure in which one of the two metal plates is plate-shaped and the spacer is omitted. In this case, first, as shown in FIG. 5, a dish-shaped metal plate IC and a flat metal plate 1d are both made of stainless steel or the like.
Thermal adhesive materials 4a and 4b formed into annular sheets similar to those described above are heat-adhered in advance to the respective peripheral parts of the IC, and the power generating element 5 is loaded onto the recessed part of the dish-shaped metal plate IC. It is placed on the receiving frame 6, and a flat metal plate 1d is placed thereon so that the heat-fusible materials 4a and 4b are in contact with each other.

Next, as shown in FIG. 6, pressure is applied from the flat metal plate 1d side using a pressing plate 7 made of a material that transmits laser light.
Under this pressure, the sealing portion is irradiated with laser light 8 through the press plate 7 for a required period of time to instantaneously heat and melt the heat-fusible materials 4a and 4b. Then, as described above, the heat-fusible material 4 is rapidly cooled and solidified to complete the sealing, and after the sealing is completed, it is removed from the receiving frame 6 to obtain the thin battery shown in FIG.

In the above two embodiments, the entire power generating element is loaded on the metal plate positioned below during sealing, but depending on the negative balance or the constituent material of the positive electrode, only this part may be fixed to the metal plate positioned above. You may let them. Further, the shapes of the receiving frame 6 and the pressing plate 7 can be changed in various ways 61, for example, the pressing plate 7
By making the metal plates concave downward, it is possible to seal a battery in which both metal plates are concave in the same manner as in the case of FIGS. 5 to 7 above.

In this invention, as a laser light source used for sealing, gas lasers such as carbon dioxide lasers, various solid lasers, semiconductor lasers, etc. can also be used.

The irradiation time of the laser beam may be appropriately set depending on the intensity of the laser beam, the type, thickness, and width of the heat-fusible material, the material and thickness of the metal plate, the material and thickness of the pressing plate, and the like.

In addition, the material constituting the press plate 7 may be any material as long as it can transmit the laser light used without being significantly affected by scattering, refraction, absorption, etc., and has excellent heat resistance and mechanical strength, and has a long life. Preferably one that can be washed. Specific examples of materials that transmit laser light in this way include zinc selenide, sodium chloride, potassium chloride, etc. Zinc selenide is particularly suitable because it is difficult to reduce strength due to moisture and is easy to handle. It is.

Next, the following test was conducted to compare the thermal effects on the power generating element between the sealing method according to the present invention and the conventional sealing method using a heat block.

<Heat Effect Test A> As shown in Fig. 8, a metal plate 1 is made of a stainless steel flat plate with a square side of 1511 nl and a thickness of 0.1 ff 1 Jf, and an alumina ceramic plate with a thickness Q of 3 m and a width of 2 ff. The rectangular annular spacer 2 has a thickness of 30 μm each.
Modified polyolefin resin (trade name: MODICP-300 manufactured by Mitsubishi Yuka Co., Ltd.) made into a rectangular annular sheet with a width of m1 and 2 WIK
M) Heat-fusible materials 4a and 4b that are hot-melt adhesives
were heat-bonded in advance, and a thermocouple 9 was bonded to the center of the metal plate 1.

The metal plate 1 and the spacer 2 were placed on the receiving frame 6 with the spacer 2 at the bottom and the heat-fusible materials 4a and 4b in contact with each other, and the thermocouple 9 was led out from the hole 6a provided in the receiving frame 6. Pressure was applied from above at 5 kq/A using a press plate 7 made of lead on the north side of selenium whose laser light transmitting part had a thickness of 5B, and the heating temperature of the sealing part was determined under this pressure (determined using thermal paper). is 250
The carbon dioxide gas laser beam was scanned with an X-Y table and irradiated for 10 seconds for one round of the sealing part so that the temperature was 0.degree. The temperature change at the center of the metal plate 1 from the start of this irradiation is calculated as
It is shown as curve A in the figure.

<Heat Effect Test B> As shown in FIG. 9, the metal plate 1 and the spacer 2 were placed on the receiving frame 6 in the same manner as in the above test A, and the downward concave heat block 10 was heated to 250°C at 5 kf/ctl. 1 under the pressure of
After contacting for 0 seconds, it was immediately replaced with a copper cool block and cooled under the same pressure. The temperature change at the center of the metal plate 1 from the start of heating at this time is shown as curve B in FIG.

As is clear from the results in Figure 10, according to the sealing method according to the present invention, the heat conduction of the metal plate is significantly reduced compared to the conventional method of heating with a heat block and then cooling with a cool block. It can therefore be seen that the thermal influence on the power generation element is significantly reduced. Furthermore, from this result, it is clear that the conventional method of using a heat block and leaving it until it cools has an extremely large thermal effect on the power generation element.

〔Effect of the invention〕

The method for sealing a thin battery according to the present invention involves inserting a heat-fusible material into the sealing part and pressing two metal plates facing each other with a press plate made of a material through which laser light can pass. Since the heat-fusible material is heated and sealed by irradiating the sealing part with laser light through a press plate under pressure, local heating of only the sealing part is easy; Furthermore, since the press plate itself is not heated and acts as a cool block, the molten heat-fusible material is rapidly cooled and solidified.

Therefore, according to the method of this invention, compared to the conventional sealing method of applying pressure until cooling using a heat block,
Thermal influence on the power generation element is significantly reduced, resulting in a high-performance battery, and the sealing time is significantly shortened, improving battery productivity.

In addition, since the method of this invention can maintain a continuous pressurized state from heating to cooling during sealing, it requires less time and effort than the conventional method of replacing and using cool blocks to promote cooling. Great sealing strength can be obtained without deterioration of adhesion or distortion of the sealing part due to pressure discontinuity.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figures 1 to 3 are longitudinal sectional views showing the sealing method according to the first embodiment of the present invention in the order of steps, and Figure 4 is a longitudinal sectional view of a thin battery sealed in the first embodiment. 5 and 6 are vertical cross-sectional views showing step by step the sealing method according to the second embodiment of the present invention, and FIG. 7 is a vertical cross-sectional view of a battery sealed in the second embodiment. , 8th
The figure is a longitudinal sectional view showing a heat effect test configuration using the sealing method of the present invention, FIG. 9 is a longitudinal sectional view showing a heat effect test structure using a conventional sealing method, and FIG. 10 shows the results of the side heat effect test. It is a temperature one-hour correlation diagram shown in FIG. 1a, 1b, IC21d...metal plate, 2--shasa, 414a14b...thermal adhesive material, 5...power generation element, 7...pressing plate, 8...laser light. Patent Applicant Hitachi Maxell Co., Ltd. 5 Figure 6 Figure 8 Figure 9 Figure 10 o s io 15 20 gin
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Claims (1)

[Claims] (1) In a method for sealing a thin battery having a structure in which a power generating element is loaded between two metal plates arranged facing each other and the peripheral areas of both metal plates are used as a sealing part, the power generating element is loaded. Both metal plates are placed facing each other with a heat-adhesive material interposed in the sealing part, and the sealing part is pressurized from one side with a press plate made of a material that transmits laser light. A method for sealing a thin battery, characterized in that the heat-fusible material is heated and sealed by irradiating a laser beam onto the sealing portion through the press plate.