JP3976148B2 - Square sealed storage battery and method for manufacturing the same - Google Patents

Description

  The present invention relates to a rectangular sealed storage battery and a manufacturing method thereof, and more particularly to a rectangular sealed storage battery using aluminum as a battery case and a lid plate that seals an opening of the battery case, and a manufacturing method thereof.

  In recent years, rectangular sealed storage batteries have been increasingly used as power sources for portable devices such as mobile phones and personal computers. As devices become smaller and lighter, they are also required to be lighter. In order to meet such demands, recent square sealed batteries have been made lighter by using aluminum for the battery case and the cover plate that seals the opening of the battery case.

  And in the square sealed storage battery using aluminum for the battery case and the cover plate as described above, the injection of the electrolyte solution into the battery has been performed through the through hole of the hollow rivet attached to the cover plate so far. After injection, a method has been employed in which a rubber plug is inserted into the through hole of the hollow rivet and the through hole is sealed using the elasticity of the rubber plug.

  However, this method has a problem in sealing performance because the electrolyte easily leaks between the hollow rivet and the rubber plug.

  Therefore, after injecting the electrolyte from the injection hole for injecting the electrolyte formed in the cover plate or the battery case, an aluminum sealing plug is inserted into the injection hole, and the sealing is performed by irradiating ultrasonic waves. There has been proposed a method in which a stopper plug is integrated with a lid plate or a battery case to seal an injection hole (Patent Document 1).

However, in this method, the sealing plug and the cover plate or the battery case are melted and integrated by frictional heat due to ultrasonic vibration, so that the amount of melting varies depending on the vibration direction, and cracks occur, resulting in a portion that cannot be sealed. was there. Furthermore, in this ultrasonic welding method, since vibration is applied to the entire battery case, the caulking portion of the insulating packing that maintains the sealing property between the hollow rivet and the cover plate is loosened, and the sealing property is reduced. There was also a problem such as partially destroying.
JP-A-8-45488

  The present invention solves the above-described instability of welding and low sealing performance in the prior art, and improves the sealing performance in a rectangular sealed storage battery using aluminum for the battery case and the cover plate. An object of the present invention is to provide a rectangular sealed storage battery having a high height.

  The present invention relates to a rectangular sealed storage battery using aluminum for a battery case and a cover plate, after injecting an electrolyte into the battery from an injection hole for injecting an electrolyte formed in the cover plate or the battery case, Insert a sealing plug into the injection hole whose top plane is circular and whose shaft length is longer than the thickness of the lid plate or battery case, and to insert the laser beam between the sealing plug and the lid plate or battery case. The said subject is solved by integrating the said sealing stopper with a cover plate or a battery case, and air-tightly sealing the said injection hole by laser welding which irradiates a joining part over 1 round.

  ADVANTAGE OF THE INVENTION According to this invention, the instability of welding, the low sealing property, etc. are eliminated, and the square sealed storage battery with high sealing property can be provided.

  As the sealing plug used for sealing the injection hole, since the lid plate and the battery case are made of aluminum, an aluminum sealing plug is most suitable. Sealing plugs made of stainless steel, nickel, etc. can also be used.

  When the sealing plug and the cover plate or the battery case are integrated by laser welding, the welding conditions are not particularly limited. For example, the output is 50 W to 300 W, particularly 120 W to 200 W, and the laser beam diameter is 0. A laser beam is applied to the joint between the sealing plug and the cover plate or the battery case at a moving speed of 1 mm / second to 15 mm / second, particularly 3 mm / second to 8 mm / second, at 3 mm to 1 mm, particularly 0.4 mm to 0.7 mm. Irradiation is preferably performed to melt the joint, and the sealing plug is integrated with the lid plate or the battery case to hermetically seal the injection hole for electrolyte injection.

  Next, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to only those examples.

Example 1
FIG. 1 schematically shows a rectangular sealed storage battery according to the first embodiment. FIG. 1 (a) is a plan view and FIG. 1 (b) is a sectional view thereof.

  In FIG. 1, 1 is a battery case that also serves as a positive electrode terminal, 2 is a lid plate that seals the opening of the battery case 1, and 3 is a sealing plug for sealing an injection hole for electrolyte injection. The battery case 1, the cover plate 2, and the sealing plug 3 are all made of aluminum. The battery case 1 is a rectangular shape having a planar shape of 6 mm × 30 mm, a height of 48 mm, a material made of aluminum as described above, and a thickness of 0.5 mm. The cover plate 2 is manufactured to a size suitable for fitting into the opening of the battery case 1 using an aluminum plate having a thickness of 1 mm. The injection hole for injecting the electrolyte formed in the lid plate 2 is a circle having a diameter of 1 mm.

  As shown in FIG. 2, the sealing plug 3 for sealing the injection hole has a circular planar shape at the top ((a) of FIG. 2), and the length of the shaft portion is a lid. It is larger than the thickness of the plate 2 ((b) in FIG. 2), and is composed of a cylinder whose upper end has a diameter of 1 mm, lower end has a diameter of 0.8 mm, and the vicinity of the lower end is tapered. Made of aluminum to suit welding.

  An electrode body 4 is accommodated in the battery case 1, a stainless steel rivet-shaped negative electrode terminal 5 is attached to the lid plate 2 via an insulating packing 6 made of polypropylene, and a lid is provided below the negative electrode terminal 5. A stainless steel seat plate 7 is fitted between the plate 2 and a polypropylene insulator 8, and an upper end portion of a tab 9 made of nickel drawn from the negative electrode of the electrode body 4 is fitted into the seat plate 7. Is fixed by welding. Prior to the insertion of the electrode body 4, a polypropylene insulator 10 is disposed at the bottom of the battery case 1 to insulate between the battery case 1 that also functions as a positive electrode terminal and the negative electrode of the electrode body 4. Yes.

  In the battery shown in the first embodiment, the battery case 1 also serves as the positive electrode terminal, but is not necessarily fixed thereto, and the battery case 1 also serves as the negative electrode terminal and is currently shown as the negative electrode terminal 5. In some cases, a positive electrode terminal is provided.

  The negative electrode terminal 5 has an initial rivet shape, and its shaft portion is passed through the through hole of the insulating packing 6, and the seat plate 7 is fitted into the shaft portion via the insulator 8, and then the tip portion is pushed. It is attached to the lid plate 2 by being fixed by crushing.

  The battery case 1 and the cover plate 2 are fitted with the cover plate 2 in the opening of the battery case 1, the welded portion between the opening end of the battery case 1 and the outer periphery of the cover plate 2 is laser-welded, and the electrolytic solution is covered. After injecting into the battery from the injection hole for injecting the electrolyte formed in the plate 2, an aluminum sealing plug 3 is inserted into the injection hole, and at the junction between the sealing plug 3 and the lid plate 2. A laser beam is irradiated at an output of 160 W, a laser beam diameter of 0.5 mm, and a moving speed of 5 mm / second for laser welding, and the sealing plug 3 is integrated with the lid plate 2 to hermetically seal the injection hole. In FIG. 1, since the sealing plug 3 is inserted into the injection hole used for injecting the electrolyte into the battery and the injection hole is sealed by laser welding, the injection hole is shown in FIG. However, the portion of the lid plate 2 where the sealing plug 3 is inserted is the portion that was the injection hole before the sealing plug 3 was inserted.

  The electrode body 4 in the battery of this Example 1 has a spiral shape produced by winding a sheet-like positive electrode using LiCoO2 as an active material and a sheet-like negative electrode using graphite as an active material in a spiral shape through a separator. As described above, the tab 9 is drawn out from the negative electrode of the spiral electrode body 4, and electrical connection from the negative electrode of the electrode body 4 to the negative electrode terminal 5 is performed via the tab 9 and the seat plate 7. The battery case 1 is electrically connected to the positive electrode of the electrode body 4.

  FIG. 2 is an enlarged view of a welded portion when the sealing plug is welded to the lid plate by laser welding, (a) is a plan view of the sealing plug, and (b) is a cross section of the welded portion. FIG. First, after injecting the electrolyte into the battery from the injection hole formed in the cover plate 2, the sealing plug 3 is inserted into the injection hole, and a laser beam is applied to the joint between the sealing plug 3 and the cover plate 2. No. 11 is output 160W, laser beam diameter 0.5mm, moving speed 5mm / sec. For one or more rounds, the above joint is melted and the sealing plug 3 is integrated with the lid plate 2 to hermetically seal the injection hole To do. At this time, if the diameter of the laser beam 11 is increased, one-shot welding can be performed with such a strength that the entire sealing plug can be melted. In FIG. 2, the cross-hatched portion with dense diagonal lines is a portion where the sealing plug 3 and the cover plate 2 are fused and integrated by laser welding.

  The shape of the sealing plug 3 is generally the cylindrical shape shown in FIG. 2 and is the cheapest, but a shape with a head that is easy to handle is also practical and improves productivity. FIG. 3 shows an example of the headed sealing plug 3. In the case shown in FIG. 3, since the peripheral portion of the head 3a is on the cover plate 2, the stability is good, the workability at the time of welding is improved, and the productivity is improved. Further, FIG. 4 shows an example in which the countersunk 12 is provided on the cover plate 2 and the headed sealing plug 3 is embedded. In this case, the welding can be performed more stably and easily as compared with the case where the headed plug is simply used, and there is also an advantage that the surface after welding becomes flat. In these FIG. 3 and FIG. 4, the cross-hatched portions are the portions in which the head 3 a of the sealing plug 3 and the lid plate 2 are fused and integrated by laser welding.

  In the first embodiment, the case where the injection hole for injecting the electrolyte is formed in the cover plate 2 has been described. However, the injection hole is formed in the battery case 1 (for example, formed on the side surface of the battery case 1). In this case, the electrolyte solution is injected into the battery from the injection hole, and then the sealing plug 3 is inserted into the injection hole, and the joint between the sealing plug 3 and the battery case 1 is laser welded. As a result, it can be hermetically sealed as in the case where the injection hole is formed in the lid plate.

Comparative Example 1
An injection hole having a diameter of 1 mm is provided in the lid plate of the battery similar to that in Example 1, and after injecting an electrolyte from the injection hole, a spherical sealing plug having a diameter of 1.2 mm is placed in the injection hole, An ultrasonic horn was applied to the tube, ultrasonic vibration was applied under the conditions of a vibration frequency of 20 kHz, an amplitude of 30 μm, and a load of 60 kgf, and the sealing plug was welded to the lid plate.

  This state will be described with reference to FIG. As shown in FIG. 5A, the lid plate 2 is formed with an injection hole 13 having a diameter of 1 mm as an injection hole for injecting an electrolyte, and after the electrolyte is injected into the battery from the injection hole 13, A spherical sealing plug 3 having a diameter of 1.2 mm is disposed above the injection hole 13, and an ultrasonic horn 14 is applied to the top of the sealing plug 3, under conditions of a frequency of 20 kHz, an amplitude of 30 μm, and a load of 60 kgf. Then, ultrasonic vibration was applied and the sealing plug 3 was welded to the lid plate 2 to obtain a state as shown in FIG. In FIG. 5A, an arrow pointing downward from above indicates the load direction, and an arrow pointing in the horizontal direction indicates the vibration direction of the ultrasonic wave.

The sealing plug is welded for 200 samples in both Example 1 and Comparative Example 1, and an air pressure of 5 kgf / cm ² is applied to the welded portion to check whether there is any air leakage. The occurrence rate of defects was investigated by assuming that there was a leakage. However, in this air leakage test, if an actual battery (mounting battery) with a sealing plug welded is used, the electrode body 4 in the battery case 1 may be adversely affected and the battery may not be usable. Therefore, a sample was prepared as a model under the same welding conditions and subjected to the air leak test.

  The results of the air leakage test are shown in Table 1. However, in order to make it easier to understand the relationship between the total number of samples subjected to the test and the number of defects, Table 1 describes the total number of samples subjected to the test in the denominator and the number of defects generated in the numerator. Defect occurrence rate was shown by the method described.

  As shown in Table 1, in Example 1, no defects were observed at all. However, in Comparative Example 1 welded by ultrasonic waves according to the conventional method, defects occurred in 14 out of 200 samples.

  In the above embodiment, after injecting the electrolyte into the battery from the injection hole for injecting the electrolyte formed in the cover plate, the upper planar shape is circular and the length of the shaft portion is in the injection hole. Shows that the injection hole is hermetically sealed by inserting a sealing plug larger than the thickness of the cover plate and laser welding, and a highly sealed square sealed storage battery can be obtained. Even when the injection hole is formed in an aluminum battery case, the specific sealing plug is inserted into the injection hole, and laser welding is performed to hermetically seal the injection hole in the same manner as described above. A high square sealed storage battery can be obtained.

An example of the square sealed storage battery of this invention is shown, (a) is the top view, (b) is the sectional drawing. FIG. 2 is an enlarged view of a welded portion between a lid plate and a sealing plug in FIG. 1, (a) is a plan view of the sealing plug, and (b) is a cross-sectional view of the welded portion. FIG. 2 is an enlarged view of a welded portion between a lid plate and a sealing plug when a sealing plug having a shape different from that shown in FIG. 2 is used. (A) is a plan view of the sealing plug. (B) is sectional drawing of the said welding part. FIG. 2 shows an enlarged view of the welded portion between the lid plate and the sealing plug when a sealing plug having a shape different from that shown in FIGS. 2 and 3 is used. It is a top view and (b) is sectional drawing of the said welding part. It is a figure for demonstrating the sealing method of the injection hole in a prior art, (a) shows the state before the sealing, (b) shows the state after the sealing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery case 2 Cover plate 3 Sealing plug 4 Electrode body 5 Negative electrode terminal 6 Insulation packing 7 Seat plate 8 Insulator 9 Tab 10 Insulator 11 Laser beam 12 Spot facing 13 Injection hole 14 Ultrasonic horn

Claims (4)

Aluminum is used for the battery case and the cover plate that seals the opening of the battery case, and a sealing plug is inserted into the injection hole for electrolyte injection formed in the cover plate or the battery case to seal the laser beam. A rectangular sealed storage battery in which the sealing plug is integrated with the lid plate or the battery case and the injection hole is hermetically sealed by laser welding that irradiates the joint between the stopper and the lid plate or the battery case for one or more rounds. The sealing plug is a rectangular sealed storage battery characterized in that the upper planar shape is circular and the length of the shaft portion is larger than the thickness of the cover plate or battery case . 2. The square sealed battery according to claim 1, wherein the injection hole for injecting the electrolyte has a counterbore. In manufacturing a battery case and a rectangular sealed storage battery using aluminum for a lid plate that seals the opening of the battery case, the electrolyte is injected into the battery from the injection hole for electrolyte injection formed in the lid plate or the battery case. After injecting the electrolytic solution, a sealing plug having a circular shape at the top and a shaft portion longer than the thickness of the cover plate or battery case is inserted into the injection hole, and the laser beam is sealed into the sealing hole. The sealing plug is integrated with the lid plate or the battery case by laser welding that irradiates the joint portion between the lid plate and the battery case over one or more rounds, and the injection hole is hermetically sealed. A battery manufacturing method. 4. The method for manufacturing a rectangular sealed storage battery according to claim 3, wherein the injection hole for injecting the electrolyte has a counterbore.

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