JP2000299099A - Battery manufacturing method - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To increase the tensile strength of a welded portion to be laser-welded. SOLUTION: A sealing plate 1 for closing an opening of a case accommodating an electrode plate group 3 in which a separator is interposed between a positive electrode plate and a negative electrode plate, and a positive electrode lead 2 taken out from the electrode plate group 3
And the first wave is a current value of 0 to 600 A and 0 to 1.0 ms.
During ec, the second wave has a current value of 0.1 to
Two or more lasers continuously irradiate for 4.0 msec, the third wave is applied at a current value of 40 to 250 A for 0 to 4.0 msec, and the fourth wave is applied for 0 to 150 A at a current value of 0 to 3.0 msec. By welding, the tensile strength of the welded portion is increased, and the reliability of the battery is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for manufacturing a battery,
In particular, the present invention relates to a current collecting technique for connecting an electrode group lead and a current collector.

[0002]

2. Description of the Related Art In recent years, information-related devices such as AV devices,
2. Description of the Related Art As electronic devices such as personal computers have become cordless and portable, there is an increasing demand for batteries used as power sources for driving them to be smaller, lighter, and have higher energy density. In particular, since a lithium secondary battery or the like is a battery having a high energy density, it is expected as a main battery for a driving power supply, and its potential market scale is also increasing.

[0003] However, if the battery is dropped or vibrated, the portion where current collection is ensured is peeled off, and the internal resistance is increased, thereby lowering reliability.
A current collecting technique for improving the contact of a portion for securing the current collection and increasing the tensile strength has been studied.

As a conventional method of securing current collection, for example, as disclosed in Japanese Patent Application Laid-Open No. 8-293299, a current collection lead is brought into contact with the inner surface of the bottom of the case, and a laser is externally applied to the bottom of the case. A method of irradiating a current collecting lead and a case by irradiating the same, Japanese Patent Laid-Open No. 9-171809
As disclosed in Japanese Patent Application Publication, a method of welding the current collecting lead and the sealing plate by laser welding while holding the positive electrode current collecting lead between the case and the sealing plate, How to spot weld to the current collector,
Alternatively, a method has been proposed in which a core material for holding an active material of an electrode plate located at the outermost periphery of the electrode plate group, for example, an aluminum foil is exposed and brought into contact with a case.

[0005]

In the conventional method of manufacturing a battery, when the current collecting leads of the electrode group are connected to a sealing plate or the like, spot welding is performed using a laser, and the spot welding is performed using two spots. Although welding is performed, if one spot of spot welding becomes a hole or if the end of the current collecting lead is partially cut off by irradiating a laser, the tensile strength is significantly reduced and performance is deteriorated. There was a problem that causes.

Further, when it is necessary to inspect holes and the like, there is a problem that the manufacturing process becomes complicated and the process failure rate increases.

Further, when the aluminum foil or the like holding the active material is exposed and brought into contact with the case, an oxide film is formed on the surface of the aluminum foil, which is not preferable from the viewpoint of current collection. .

Accordingly, an object of the present invention is to increase the tensile strength by welding a current collecting lead and a current collector with a laser to improve reliability and productivity in manufacturing a battery.

[0009]

In order to solve the above-mentioned problems, in a method of manufacturing a battery according to the present invention, an electrode plate group formed by interposing a separator between a positive electrode plate and a negative electrode plate is provided. The current collecting lead is continuously laser-welded to the current collector at two or more points.

[0010] By doing so, when the battery is dropped or vibrated, it is possible to prevent a decrease in the tensile strength of the current collecting portion caused by a hole phenomenon or the like. Further, an increase in the internal resistance of the battery can be prevented, and the reliability of the battery can be improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention can be embodied in the forms described in the respective claims, and the embodiments will be described below.

According to the present invention, two or more current collecting leads of an electrode group formed by interposing a separator between a positive electrode plate and a negative electrode plate are continuously welded to a current collector at two or more points.

[0013] Further, the tensile strength of the current collecting portion can be increased to prevent the internal resistance of the battery from increasing due to falling and vibration.

[0014] Further, a sealing plate for closing an opening of a case for accommodating an electrode plate group having a separator interposed between a positive electrode plate and a negative electrode plate, and a current collecting lead of the electrode plate group, A reinforcing plate attached to a sealing plate that seals an opening of a case that houses an electrode group having a separator interposed between a plate and a negative electrode plate, and a current collecting lead of the electrode group, or a positive electrode plate. A case for accommodating an electrode group having a separator interposed between the electrode plate and a negative electrode plate, and a current collecting lead of the electrode plate group, or an electrode plate having a separator interposed between a positive electrode plate and a negative electrode plate The case for accommodating the group, and the current collector for holding the active material of the electrode plate located at the outermost position of the electrode plate group, the first wave has a current value of 0 to 600 A and a current value of 0 to 1.0 msec. Two waves are 0.1 to 4.0 msec at a current value of 150 to 450 A,
The third wave has a current value of 40 to 250 A and is 0 to 4.0 mse.
c, the fourth wave is a current value of 0 to 150 A and 0 to 3.0 mse
c Laser welding is performed continuously at two or more points depending on the waveform to be irradiated.

[0015] Then, by specifying the waveform to be irradiated as described above and performing laser welding continuously at two or more points,
Even if the output is weaker than in the case of spot welding, no hole phenomenon occurs, and the tensile strength of the current collecting portion is increased, which is effective.

Further, in the case of laser welding, when the central portion of the welded portion is welded, or the central portion is continuously welded, or continuously and intermittently welded, the tensile strength of the current collecting portion is increased. Is preferred.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

Example 1 FIG. 1 is a projection view of a welded portion of a rectangular nonaqueous electrolyte battery manufactured according to Example 1. 1
Is an aluminum sealing plate, 2 is an electrode group 3 for current collection
And is welded to the sealing plate 1 by continuous laser irradiation. Reference numeral 4 denotes a resin insulating gasket, and reference numeral 5 denotes a nickel-plated iron washer, which also serves as a negative electrode terminal. Reference numeral 6 denotes a negative electrode lead taken out of the negative electrode plate of the electrode plate group 3 and is welded to the washer 5. Reference numeral 7 denotes a liquid injection port provided in the sealing plate 1, reference numeral 8 denotes a hole for a safety valve, and reference numeral 9 denotes a nickel-plated iron rivet, which also serves as a positive electrode terminal. The electrode group 3 is formed with a separator interposed between the positive electrode plate and the negative electrode plate.

This prismatic non-aqueous electrolyte battery is manufactured as follows. The positive electrode plate is made of LiCoO ₂ which is an active material.
Then, a mixture prepared by mixing carbon black as a conductive agent and an aqueous dispersion of polytetrafluoroethylene as a binder at a weight ratio of solids of 100: 3: 10 is applied to both surfaces of the aluminum foil. After drying, rolling,
It is cut into a predetermined size, and an aluminum positive electrode lead 2 is welded to an aluminum foil.

The negative electrode plate comprises a carbonaceous material as a main material, and a styrene-butadiene rubber-based binder in a weight ratio of 100:
The mixture mixed at a ratio of 5 was applied to both sides of a copper foil, dried, rolled, and then cut into a predetermined size. A nickel negative electrode lead 6 was welded to the copper foil. I have.

As the separator, a microporous film made of polyethylene is used and wound with a separator interposed between the positive electrode plate and the negative electrode plate to form an electrode plate group 3 having an oblong upper surface. The electrode group 3 in which the positive electrode lead 2 is welded to the sealing plate 1 is inserted into a case, and the sealing plate 1 and the case are sealed by laser welding.

As shown in FIG. 1, the negative electrode lead 6 is resistance-welded to a nickel-plated iron washer 5, and then the positive electrode lead 2 is arranged so as to be in contact with the sealing plate 1. 0 to 1.0 m at a current value of 0 A to 60 A
The second wave is a current of 150 A to 450 A for 0.1 to 4.0 msec as a second wave, and the third wave is 40 to 250 as a third wave.
The current value of A is 0 to 4.0 msec, and the fourth wave is 0 to 0
Welding was performed by continuously irradiating a laser having a waveform of 0 to 3.0 msec at a current value of 150 A, and the positive electrode lead 2 and the sealing plate 1 were joined at two or more welded portions 10.

Next, in order to inject a predetermined amount of the electrolyte from the injection port 7, a pipe having a rubber ring attached to the tip thereof is inserted into the injection port 7, and this pipe has a three-way cock. The three-way cock is connected to a battery, a vacuum pump, and a pump containing an electrolyte, respectively. The pressure inside the battery was reduced by a vacuum pump through a pipe, and then the cock was switched to inject the electrolyte by injecting the electrolyte from the pump. It is to be noted that once the inside of the battery was depressurized, the injection of the electrolytic solution was facilitated, and ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed in the electrolytic solution at a molar ratio of 1: 3. A solution obtained by dissolving lithium hexafluorophosphate at a concentration of 1 mol / liter as a solute in a solvent was used.

As described above, the positive electrode lead 2 was welded to the sealing plate 1 at two or more points by continuously irradiating the laser with the condition of the irradiating waveform controlled to a predetermined value from the first wave to the fourth wave. Table 1 shows a comparison between the case of the embodiment and the case of the conventional example in which the positive electrode lead and the sealing plate were spot-welded using a laser. In the case of the embodiment, by welding two or more points with a laser, the welding area can be increased and the welding strength can be increased, the tolerance for holes can be increased, and the process defect rate can be reduced.
Table 1 shows the process failure rates according to the conventional example and the example, and the average of the tensile strengths in the case where one battery had a hole in each of five batteries.

[0025]

[Table 1]

As is clear from Table 1, in the case of the embodiment, the process failure rate is reduced and the tolerance for holes is higher than in the case of the conventional example.

(Example 2) When a laser was continuously irradiated using the waveform under the same conditions as in Example 1, the reliability due to the difference in the irradiation method was confirmed and shown in Table 2. As shown in FIG. 2, when the welded portion 10 is formed by irradiating the central portion of the positive electrode lead 2, and when the welded portion 10 is formed by continuously and intermittently irradiating the laser as shown in FIG. ,
As shown in FIG. 1 and FIG. 1, a case where the welded portion 10 is formed over the entire width of the positive electrode lead 2 will be described. When the entire width direction is welded by laser irradiation, the area of the welded part is maximized, so the tensile stress applied to one spot is small, but because of the thermal distortion due to welding, the tensile strength is higher than in other cases. Is also weak. Also, the positive electrode lead 2
When the central part of the lead is welded or by intermittently irradiating a laser,
, The tensile strength can be increased compared to the case of full irradiation. Table 2 shows changes in the tensile strength and the internal resistance in the drop test in each case. Reference numeral 9 denotes a nickel-plated iron rivet also serving as a terminal.

[0028]

[Table 2]

As is evident from Table 2, the reliability can be improved by continuously irradiating the central portion of the positive electrode lead with the laser or by intermittently irradiating the laser.

Example 3 A metal current collector 11, for example, an aluminum foil, which is a core material holding an active material of an electrode plate constituting the electrode plate group 3, is exposed, and the metal current collector 11 and the electrode plate are exposed. A case where the case 12 accommodating the group 3 is welded by continuously irradiating a laser will be described with reference to FIG. When the positive electrode lead is welded to the sealing plate 1, the area that can be irradiated with the laser is small, so that it is necessary to make the length of the positive electrode lead longer than necessary. When the elongated positive electrode lead is stored in the case 12, it is necessary to bend the positive electrode lead and store the bent positive electrode lead, thereby increasing the process failure rate. Therefore, by continuously welding two or more points of the exposed portion of the metal current collector 11 from the outside of the case 12 with a laser to form the welded portion 10, the irradiation area can be increased, and the positive electrode lead can be increased. Can be omitted, and productivity can be improved by simplifying this step. Table 3 shows the process defect rate and process capability when the positive electrode lead and the sealing plate were continuously irradiated and welded, and when the exposed metal current collector 11 and the case 12 were continuously irradiated and welded. Was.

[0031]

[Table 3]

As is apparent from Table 3, the metal current collector holding the active material of the electrode plate constituting the electrode group is exposed, and the laser is continuously irradiated to expose the exposed portion of the metal current collector and the case. By welding at two or more points, the process capability can be increased, and the process defect rate can be further reduced.

(Embodiment 4) An effect other than the tensile strength by irradiating a laser with a controlled waveform condition as in Embodiment 1 will be described. In conventional spot welding, a single pulse is often used,
In such a case, impurities may adhere to the surface to be welded by the laser, or a blow hole or a crack may occur due to rapid cooling. In particular, in the case of laser welding aluminum, high energy is required by spot welding, so that there are many effects on the surroundings due to blow holes and spatters. Therefore, for example, the first wave is set at a current value of 340 A for 0.2 msec, and the second wave is set at 0.2 A at a current value of 200 A.
For 2 msec, the third wave is applied for 1.0 ms at a current value of 160 A.
Table 1 shows the process failure rate when continuously welding with a laser using a waveform that irradiates the fourth wave with a current value of 120 A for 2.5 msec during ec and when spot welding is performed.
It is as shown in.

[0034]

[Table 4]

As is clear from Table 4, the occurrence of blowholes and cracks can be controlled by irradiating a laser with a waveform controlled to a predetermined value and continuously welding.

In the above embodiment, the case where the positive electrode lead 2 is laser-welded to the sealing plate 1 as the welding of the current collecting portion has been mainly described, but the negative electrode lead 6 may be laser-welded to the reinforcing plate such as the washer 5. Even when the negative electrode lead 6 is laser-welded to the case, the same can be performed.

[0037]

As described above, the present invention is carried out in the above-described state, so that the defect rate in the step of securing the current collection can be reduced and the productivity can be increased. By increasing the strength, reliability can be improved when the battery is dropped or vibrated.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a rectangular nonaqueous electrolyte battery according to a first embodiment of the present invention.

FIG. 2 is a projection view of a main part of a rectangular nonaqueous electrolyte battery according to a second embodiment of the present invention.

FIG. 3 is a projection view of another main part of the prismatic nonaqueous electrolyte battery according to the second embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a square nonaqueous electrolyte battery according to a third embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sealing plate 2 positive electrode lead 3 electrode plate group 5 washer (reinforcing plate) 6 negative electrode lead 10 welded part 11 metal current collector 12 case

Continued on the front page F-term (reference) 4E068 BH01 DA09 5H022 AA09 BB11 BB17 CC08 CC11 CC16 5H029 AJ11 AJ14 AK03 AL06 AM03 AM05 AM07 BJ04 CJ05 DJ05 DJ07 HJ00 HJ17

Claims (8)

[Claims] 1. A method for manufacturing a battery in which a current collecting lead of an electrode group formed by interposing a separator between a positive electrode plate and a negative electrode plate is laser-welded at two or more points to a current collector. 2. A method according to claim 1, wherein a current collecting lead of an electrode group having a separator interposed between a positive electrode plate and a negative electrode plate and a sealing plate for sealing an opening of a case accommodating the electrode group are formed by a first wave. Is 0-6
0 to 1.0 msec at a current value of 00 A, and the second wave is 150
0.1-4.0 msec at a current value of ~ 450 A, 0-4.0 msec at a current value of 40-250 A,
A method for manufacturing a battery in which two or more points are continuously laser-welded by a waveform in which waves are irradiated at a current value of 0 to 150 A for 0 to 3.0 msec. 3. A current collecting lead of an electrode group having a separator interposed between a positive electrode plate and a negative electrode plate, and a reinforcing plate attached to a sealing plate for closing an opening of a case for accommodating the electrode group. Is 0 to 1.0 msec when the first wave is a current value of 0 to 600 A.
c, the second wave is a current value of 150 to 450 A and is 0.1 to 4.
0 msec, the third wave has a current value of 40 to 250 A,
4.0msec, 4th wave is 0 ~ 150A current value 0 ~
A method for producing a battery in which laser welding is continuously performed at two or more points according to a waveform irradiated with 3.0 msec. 4. A current collecting lead of an electrode group in which a separator is interposed between a positive electrode plate and a negative electrode plate, and a case accommodating the electrode group, wherein the first wave has a current value of 0 to 600 A. 0-1.
0 msec, the second wave has a current value of 150 to 450 A, and
1 to 4.0 msec, the third wave has a current value of 40 to 250 A, 0 to 4.0 msec, and the fourth wave has a current value of 0 to 150 A, 0 to 3.0 msec. Manufacturing method of the battery to be welded. 5. A current collector for holding an active material of an electrode plate located at the outermost position of an electrode plate group having a separator interposed between a positive electrode plate and a negative electrode plate, and a case for accommodating the electrode plate group. The first wave is 0 to 1.0 msec at a current value of 0 to 600 A, and the second wave is 0.1 to 4.0 msec at a current value of 150 to 450 A.
c, the third wave is 0 to 4.0 ms at a current value of 40 to 250 A
ec, the fourth wave is 0 to 3.0 ms at a current value of 0 to 150 A
A method for manufacturing a battery in which two or more points are continuously welded by an ec irradiation waveform. 6. The method for manufacturing a battery according to claim 1, wherein a central portion of the welded portion is laser-welded. 7. The method for manufacturing a battery according to claim 1, wherein the welding portion is continuously and intermittently laser-welded. 8. The method for producing a battery according to claim 1, wherein a central portion of the welded portion is continuously laser-welded.