JPS62219459A - Manufacture of thin battery - Google Patents

Abstract

PURPOSE:To prevent a thermal effect from being exercised on an electricity generation unit in sealing, by disposing the electricity generation unit between two metal plates, using a pressure jig made of an electric resistor, to press a melt-bondable material on the peripheral portions of the metal plates, and applying electricity to the jig to melt and bond the material to the metal plates. CONSTITUTION:A melt-bondable material 4a is stuck to a spacer 2 stuck to the peripheral portion of a metal plate 1a. An electricity generation unit 5 comprising a positive and a negative electrodes and a separator is disposed inside the material 4a. The unit 5, the spacer 2 and the material 4a are then placed in a recessed frame 6. Another metal plate 1b to which another melt- bondable material 4b is stuck is disposed so that both the materials 4a, 4b are put in contact with each other. The materials 4a, 4b are then pressed by a pressure jig 7 made of an electric resistor such as a tungsten alloy. An electrical current is caused to flow through the jig 7 to heat it to melt-bond the materials 4a, 4b to each other. After that, the electrical current is stopped and forcible cooling is performed, so that a thin battery is manufactured. Productivity is thus enhanced without exercising a thermal effect on the electricity generation unit 5 in sealing.

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. The present invention relates to a manufacturing method.

[Conventional technology]

In button-type or coin-type batteries, 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 in between. Sealing methods are widely used. However, as electronic devices have become smaller, lighter, and thinner in recent years,
There is a demand for batteries used in these devices to be thin, with a total thickness of 1) or less, and even 0.5 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 hermetically sealable ceramics can be handled as solid parts formed into sheet shapes and sealed. It is considered viable because it is easy to operate and there is no risk that it will flow into the battery like a paint solution adhesive and mix with the electrolyte, degrading battery performance (unspecified literature).

[Problem that the invention seeks to solve]

However, the conventional method of sealing thin batteries using the above-mentioned heat-fusible materials generally uses a heat block formed into a large size to maintain the temperature at a high temperature, and the block is used to pressurize and seal the battery tightly. After the heat-fusible material inserted in the part is heated and melted, the above-mentioned pressure is continued until the material is cooled and solidified, thereby fusion-sealing the material. For this reason, there were problems in that the loaded power generation elements were affected by heat during the long heating period until cooling, resulting in a decrease in battery performance, and in addition, sealing took time, resulting in poor productivity.

On the other hand, in order to avoid this, it is possible to speed up the cooling process 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. Furthermore, even in this method of replacing the rotor with a single rub block, the cooling rate was not sufficient, and the thermal effect on the power generation element could not be ignored.

[Means for solving problems]

In this invention, unlike the conventional heat block method described above, a pressing jig made of a resistor is used as a heating means, and the jig generates heat by applying electricity to the jig while pressing the sealing part with this jig. The heat-sealable material is heated and fused.

In other words, according to this method, even if the shape of the pressing jig is small enough to match the shape of the sealing part, by energizing it, the required amount of thermal energy can be quickly obtained, and when this energization is removed, Due to its small size, it can be cooled quickly. Moreover, since these heating and cooling operations can be performed continuously while pressing the sealing part with the jig, the sealing work is simpler and faster than with the conventional heat block method, and the battery contents (power generation elements) It is possible to avoid thermal effects on the parts, and improve the adhesion and reliability of the thermally bonded parts.

〔Example〕

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

Figures 1 to 5 show two electrodes constituting the positive and negative electrode current collector plates arranged opposite to each other.
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 this adhesive 3, other adhesives such as hot-melt adhesives and heat-fusible materials such as ceramics that can be hermetically sealed, and solution-based adhesives can be used; As the heating and fusing means, various methods can be employed, such as local heating by electrical heating such as pulsed current, 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 generation 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. place 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 the re-heat-fusible materials 4a and 4b are in contact with each other.

Next, using a pressing jig 7 made of a resistor such as tungsten alloy, copper tungsten alloy, molybdenum/molybdenum carbide, copper chromium, etc. as shown in FIG. Pressure is applied from the side of the other metal plate 1b, and a pulse-controlled current is passed through the jig 7 to generate heat, and the peripheral part of the metal plate 1b, that is, the sealing part, is heated and pressed for the required time to heat fusion. The flexible materials 4a and 4b are heated and melted in a short time. Thereafter, the current is turned off while the jig 7 remains under pressure, and cooled argon gas is blown onto the side surface of the jig 7 through a ventilation hole 8.times.8.degree. to perform forced cooling. After cooling and solidifying, it is extracted and sealing is completed. FIG. 5 shows the thin battery taken out from the receiving frame 6 after this sealing is completed.

6 to 8 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. 6, a heat-fusible material 4a formed into an annular sheet similar to that described above is formed around each of the dish-shaped metal plate IC and the flat metal plate 1d, both of which are made of stainless steel or the like. , 4b are heat-adhered in advance, the power generation element 5 is loaded onto the recess of the dish-shaped metal plate IC, and the power generation element 5 is placed in the recessed receiving frame 6.
Place the flat metal plate 1d on top so that the heat-fusible materials 4a and 4b are in contact with each other! place

Next, as shown in FIG. 7, pressure is applied from the flat metal plate 1d side using a pressing jig 7 made of a resistor, and under this pressure, the pressing jig 7 is energized in the same manner as described above to bond the heat fusion. material 4a, 4
Instantly heat and melt b. Then, by removing the electricity and performing forced cooling again, the heat-fusible material 4 is rapidly cooled and solidified to complete the sealing process as described above. Obtain the thin battery shown in the figure.

In the above two embodiments, the entire power generation element is loaded on the metal plate positioned below during sealing, but depending on the constituent material of the negative electrode or the positive electrode, only this part may be fixed to the metal plate positioned above. It's okay. Furthermore, the shapes of the receiving frame 6 and the pressing jig 7 can be changed in various ways. Furthermore, it is also possible to seal a battery in which two metal plates are both concave in the same manner as in the case of FIGS. 6 to 8 above.

In the above-described embodiment, the pressing jig 7 is energized by passing a pulsed current, but it is not limited to a pulsed current, and a normal current may be passed. Further, in the above example, cooling is forcibly performed using the ventilation holes 8, 8'', but a natural cooling method can also be adopted.In other words, in the above heating method, the shape of the jig 7 matches the shape of the sealing part. Since it has a small profile, it naturally cools down in a short time when the power is turned off.

〔Effect of the invention〕

As explained above, in the present invention, a pressing jig made of a resistor is used as a heating means for the sealing part, and the pressing jig is used to apply electricity while applying pressure to generate heat, thereby heating the sealing part and applying pressure. Since the structure is such that the power is turned off and cooled while maintaining the state, the thermal effect on the power generation element is significantly reduced compared to the conventional sealing method using a heat block, resulting in a high-performance battery. At the same time, the sealing time is significantly shortened and battery productivity is improved.

In addition, with this invention method, a continuous pressurized state can be maintained from heating to cooling during sealing, so it requires less effort than the conventional method of replacing and using cool blocks to promote cooling. , large sealing strength can be obtained without causing deterioration in adhesion or distortion of the sealing part due to discontinuous pressurization.

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

Thermal Effect Test A〉 As shown in Figure 9, a square with a - side of 15 m and a thickness of 0.1
A metal plate 1 made of a flat stainless steel plate with a thickness Q and 3
A rectangular annular spacer 2 made of alumina ceramic with a width of 21 mm and a width of 21 mm is coated with a modified polyolefin resin (product name: MOI: IIcP-300M, manufactured by Mitsubishi Yuka Co., Ltd.) hot, each made into a rectangular annular sheet with a thickness of 30 μm and a width of 2 mm. Heat-fusible materials 4a and 4b, which are melt adhesives, were bonded by heating 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. A pressure of 5 kg/- is applied from above using a pressing jig 7 whose pressing part is made of a resistor with a width of 2 squares, and a pulse current is applied so that the heating temperature of the sealed part becomes 250°C under this pressure. The power was turned on.

After 10 seconds, the electricity was turned off, and argon gas was blown through the ventilation ports 8, 8. to cool it down. The temperature change at the center of the metal plate 1 from the start of current application at this time is shown as a curve A in Fig. 1).

<Heat Effect Test B> As shown in Fig. 10, the metal plate 1 and spacer 2 were placed on the receiving frame 6 in the same manner as in Test A above, and a downwardly concave heat block 10 heated to 250°C was heated to 5 kg/-. After contacting under pressure for 10 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 Figure 1).

As is clear from the results in Figure 1), according to the method of the present invention, the heat conduction of the metal plate is significantly lower than that of the conventional method of heating with a heat block and then cooling with a cool block. Therefore, it can 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.

[Brief explanation of drawings]

1 to 3 are longitudinal sectional views showing the method according to the first embodiment of the present invention in the order of steps, FIG. 4 is a perspective view showing a pressing jig and forced cooling means used in the above method, and FIG. 6 and 7 are vertical cross-sectional views showing the method according to the second embodiment of the present invention in the order of steps, and FIG. 8 is a longitudinal cross-sectional view of the thin battery manufactured in the second embodiment. A longitudinal cross-sectional view of the manufactured battery,
Fig. 9 is a vertical cross-sectional view showing the heat-effect test configuration according to the method of the present invention, Fig. 1O is a longitudinal cross-sectional view showing the heat-effect test configuration according to the conventional method, and Fig. 1) shows the results of the above-mentioned re-heat effect test. It is a temperature one-hour correlation diagram. la, lb, lc, Ld...metal plate, 2...spacer, 4, 4a, 4b...thermal adhesive material, 5...power generation element, 7...pressing jig patent applicant Hitachi Maxell Co., Ltd. Figure 1 Figure 2 Figure Ia, 1b; Metal plate 2; Syasa 4a, 4b; , ld; n is Fig. 8 Fig. 10 Fig. 1) Time (to))

Claims (1)

[Claims] (1) In a method for manufacturing a thin battery having a structure in which a power generating element is loaded between two metal plates arranged facing each other, and the periphery of both metal plates is used as a sealing part, both The metal plates are placed facing each other with a heat-sealable material interposed in the sealing part, and the sealing part is pressurized from one side with a pressing jig made of a resistor, and the jig is pressed under this pressure. A method for manufacturing a thin battery, characterized in that the heat-fusible material is heated and fused-sealed by applying electricity.