JP2002056837A - Weld-sealed battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a weld-sealed battery allowing improvement of reliability by preventing tab cutting inside the battery even when vibration such as falling of the battery is applied. SOLUTION: This weld-sealed battery comprises a battery exterior can 60 for storing a spiral electrode body 40 and a positive electrode collector tab 24 formed by forming a substantially U-shaped notch 23 in a core body exposed part of a positive electrode plate 20 disposed in the outer most peripheral part of the spiral electrode body 40 and raising the notch 23. The positive electrode collector tab 24, the battery exterior can 60, and a sealing lid 50 are welded with each other with the positive electrode collector tab 24 sandwiched between an opening edge of the battery exterior can 60 and the sealing lid 50. An adhesive tape 25 with a width narrower than a width of a root part of the positive electrode collector tab 24 is adhered from a surface facing to the spiral electrode body 40 of the collector tab 24 to the outer most peripheral surface of the core body of the spiral electrode body 40 through a folded part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small and portable welding sealed battery, and more particularly to a shape of a sealing lid of a laser sealed square ion battery.

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 9-171809, the present applicant discloses a portable small sealed battery having an opening edge (end) of a battery outer can in which a power generation element is housed. In FIG. 13A, the core 101 of either the positive electrode plate or the negative electrode plate is provided on the outermost peripheral portion of the power generation element 106. After placing, and making a substantially U-shaped cut (cut line) 102 in the exposed portion of the core body 101, FIG.
As shown in FIG. 14B, the cut 102 is folded in the direction of the opening of the battery outer can to form a current collecting tab 103. Thereafter, as shown in FIG. The three pieces were sandwiched between the edge 104a and the sealing lid 105, and in this state, the three pieces were sealed by laser welding.

In this case, when a shock such as a drop is applied to the battery and stress is applied to the current collecting tab, the current collecting tab 1
In order to prevent the current collecting tab 103 from being cut at the base portion 103a of 03 and increasing the internal resistance of the battery, the current collecting tab 103 and a part of the cut 102 are provided with a cut-prevention such as to cover them. The tape 107 was stuck.

[0004]

As described above, if the tape 107 for preventing cutting is adhered, the current collecting tab 10
The current collecting tab 103 can be prevented from being cut at the base portion 103a of the third. However, in this case, when a shock such as a drop is applied to the battery and stress is applied to the current collecting tab, the power generating element 106 tends to move downward (direction A in the figure) as shown in FIG. , Current collecting tab 103
Is pulled down. For this reason, the current collecting tab 103 is cut off in the vicinity of the welded portion 108, which causes a new problem that the internal resistance of the battery increases.

[0005] The present invention has been made in consideration of the above-mentioned conventional problems, and even when a vibration such as dropping a battery is applied to apply a stress to a current collecting tab,
An object of the present invention is to provide a welded sealed battery that can prevent a current collecting tab from being cut off, suppress an increase in internal resistance of the battery, and improve reliability.

[0006]

In order to achieve the above object, according to the present invention, there is provided a spiral electrode body in which a positive electrode plate and a negative electrode plate are wound via a separator, and a battery outer can housing the spiral electrode body. And a substantially U-shaped cut is made in the exposed portion of the core of the positive electrode plate or the negative electrode plate located at the outermost peripheral portion of the spiral electrode body, and the cut is cut and raised to be folded toward the opening side of the battery outer can. A formed current collecting tab, and a sealing lid for sealing the opening of the battery outer can, and the current collecting tab is sandwiched between the opening edge of the battery outer can and the sealing lid. In the state, in a welded sealed battery of a structure in which the current collection tab, the battery outer can and the sealing lid are welded,
From the surface of the current collecting tab facing the spiral electrode body to the outermost core surface of the spiral electrode body via the folded portion, a reinforcing member narrower than the width of the base portion of the current collecting tab is attached. It is characterized by being.

With the above configuration, when vibration such as dropping of the battery is applied to apply stress to the current collecting tab, a virtual extension line of a substantially U-shaped cut is formed in the exposed portion of the core. Along the line, a crack occurs in the exposed portion of the core (that is, the current collecting tab becomes longer). Therefore, it is possible to prevent the occurrence of tab breakage near the welding portion of the current collecting tab,
An increase in internal resistance of the battery can be suppressed. More specifically, in comparison with the prior art, a reinforcing member is adhered from the surface of the current collecting tab facing the spiral electrode body to the outermost core surface of the spiral electrode body via the folded portion. (Ie, a reinforcing member is attached to the base of the current collecting tab), so that even if stress is applied to the current collecting tab, the tab of the current collecting tab at the base of the current collecting tab Cutting can be prevented. Moreover, since a crack is generated in the exposed portion of the core (that is, the current collecting tab becomes longer), stress near the welded portion is reduced, and the tab of the current collecting tab can be prevented from being cut.

The reason why the width of the reinforcing member is made narrower than the base portion of the current collecting tab is that if the width of the reinforcing member is wider than the base portion of the current collecting tab, the current collecting tab may be stressed. When cracks are added, no crack is generated in the exposed portion of the core body along the virtual extension line of the cut, so that the current collecting tab is cut off in the vicinity of the welded portion as in the conventional technique.

According to a second aspect of the present invention, in the first aspect of the present invention, a spacer exists between the sealing lid and the spiral electrode body, and the reinforcing member extends to a contact point between the spacer and the spiral electrode body. Is extended, or the contact is covered with an insulating member different from the reinforcing member.

As described above, if the reinforcing member extends to the contact point between the spacer and the spiral electrode body, or if the contact point is covered by an insulating member different from the reinforcing member, the positive current collecting tab Even if the positive electrode current collecting tab becomes long enough to cause the slack, the slack portion does not enter from the gap between the spacer and the spiral electrode body. Therefore, occurrence of a short circuit inside the battery can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment A first embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a partial cross-sectional view of the sealed battery according to the first embodiment.

As shown in FIG. 1, the welded sealed battery of the present invention has a battery outer can 60 having a rectangular cylindrical shape with a bottom. Inside the battery outer can 60, a positive electrode, a negative electrode, A flat spiral spiral electrode body 40 composed of an ion-permeable separator that separates the electrodes is housed. At the open end of the battery outer can 60, a sealing lid 50 having a positive terminal 70 is provided.
Are welded, thereby sealing the battery. The outermost positive electrode core exposed portion 21 of the spiral electrode body 40
Is formed with a notch 23, and this notch 23
To form a positive electrode current collecting tab 24. The positive electrode current collecting tab 24 extends along the inner wall of the battery outer can 60 to the opening end of the battery, and the laser is held in a state of being sandwiched between the sealing lid 50 and the inner wall surface of the battery outer can 60. Welded. Further, an adhesive tape 25 as a reinforcing member is adhered from the surface of the positive electrode current collecting tab 24 facing the spiral electrode body 40 to the positive electrode core exposed portion 21.

The details of each component of the above-mentioned sealed battery will be described below. FIG. 2A is a side view of the positive electrode plate according to the first embodiment, and FIG. 2B is a front view.
As shown in these figures, the positive electrode plate has a length of 335 mm, a width of 38 mm, and a thickness of 20 μm.
In principle, a positive electrode active material (slurry) 22 composed of LiCoO ₂ as a main component and other components such as graphite, carbon black, and polyvinylidene fluoride dissolved in N-methyl-2-pyrrolidone is applied to both surfaces thereof, and then the solvent is dried. It is compressed to the thickness of A substantially U- or U-shaped notch 23 is provided on the outermost side when inserted or inserted in the battery outer can 60. As shown in FIG. 3, the width from the positive electrode core 27 existing inside the notch 23 to the positive electrode core 28 existing in the virtual extension line 26 of the notch 23 is narrower than the notch 23. The adhesive tape 25 made of polypropylene is stuck.

The positive electrode active material is naturally not attached to the portion of the positive electrode core body 21 where the cuts 23 are provided, and the positive electrode active material is further attached to the surface located closer to the battery outer can 60. The reason for not being provided is to achieve further electrical contact between the positive electrode core body 28 and the battery outer can 60.

FIG. 4A is a side view of the negative electrode plate according to the first embodiment, and FIG. 4B is a front view. As shown in these figures, the negative electrode plate was composed mainly of natural graphite powder on both surfaces of the copper foil of the negative electrode core 31 having a length of 315 mm, a width of 39 mm and a thickness of 18 μm, and was dissolved in N-methyl-2-pyrrolidone. A negative electrode slurry made of polyvinylidene fluoride was applied, dried and then compressed to a predetermined thickness, and a negative electrode current collecting tab 33 made of nickel was directly applied to a copper foil of a negative electrode core at a winding center portion described later. It is attached.

FIG. 5 is a sectional view showing the structure of the spiral electrode body 40 according to the first embodiment. As shown in the figure, a spiral electrode body 40 is formed by winding a positive electrode plate 20 and a negative electrode plate 30 via a polyethylene separator 41 which is slightly wider than both. In this case, the spirally wound electrode body is wound so that the one-side exposed portion of the positive electrode plate on which the positive electrode active material is not applied is located at the outermost peripheral portion of the spiral electrode body. And under this, an adhesive tape (not shown) is attached to the end of the volume,
The bottom is covered with an insulating tape (not shown) to prevent contact with the battery can.

Here, the positive electrode current collecting tab 24 is formed by cutting and raising the cut portion 23 shown in FIG. 2 and FIG. 3, and at this time, an electrode plate of the same polarity is located on the inner winding center side of the battery. The reason for this is to prevent an internal short circuit from occurring even if the separator 41 is damaged by burrs in the cutouts 23.

FIG. 6 is a half sectional view of the sealing lid according to the first embodiment, and FIG. 7 is a perspective view of the sealing lid according to the first embodiment as viewed from obliquely below. As shown in FIG. 6 and FIG.
A sealing plate 51 having a through hole near the center, a metal hollow cap 53 disposed in the through hole via an insulating gasket 52, and a battery electrically connected to the upper end of the hollow cap 53. A cap (not shown, which also serves as a negative electrode external terminal), a current collecting terminal plate 54 electrically connected to the hollow cap 53, and both interposed between the sealing plate 51 and the current collecting terminal plate It consists of an insulating plate 55 that is electrically insulated.

Then, the insulating gasket 52, the insulating plate 5
5 and the current collecting terminal plate 54 are fixed to the sealing plate 51 by caulking the upper and lower ends of the hollow cap 53. Further, spacers 56 are arranged at both ends of the insulating plate 55. The spacer 56 is formed integrally with the insulating plate 55, and is disposed between the sealing plate 51 and the spiral electrode body 40, so that the spiral electrode body 40 does not swing in the vertical direction when a normal battery is used. Is to do so.
The current collecting terminal plate 54 is partially cut and raised in the downward direction, and the negative electrode current collecting tab 33 connected to the negative electrode core 31 described above is electrically connected to this portion.

Here, a method of manufacturing the sealed battery having the above structure will be described with reference to FIG. First, as shown in FIG. 2A, the sealing lid 50 is positioned above the spiral electrode body 40 having an adhesive tape at a key point for preventing contact with the bottom of the battery outer can, prevention of unraveling, and the like. Together with the spiral electrode body 40
Notch 23 formed in the outermost positive electrode core exposed portion 21
Is formed, and an adhesive tape 25 is attached to the inside of the cut 23 and the virtual extension lines 26 of the cut 23.
Next, as shown in FIG. 2B, the cut 23 is cut and raised, and is bent upward to form the positive electrode current collecting tab 24.

Thereafter, the battery is inserted into a rectangular battery outer can 60 made of aluminum. At this time, the positive electrode current collecting tab 24 derived from the positive electrode plate 20 is extended along the inner wall of the battery outer can 60 to the battery opening end, and the upper end portion is further formed on the outer peripheral side of the sealing lid 50 and the inside of the battery outer can 60. The sealing lid 50 is placed over the opening edge of the battery outer can 60 while being sandwiched between the wall surfaces. Thereafter, the fitting portion between the battery outer can 60 and the sealing plate 51 is irradiated with a laser beam to weld the portion to seal the battery. And, together with the positive electrode current collecting tab 24 and the battery outer can 6
0 is electrically and strongly connected.

Further, the battery outer can 6
Then, a non-aqueous electrolyte is injected into the inside of the battery pack 0, and a battery cap is placed in the through hole. As a result, the sealed battery shown in FIG. 1 is manufactured.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described with reference to FIGS. 9 is a side view of a main part of the welded-sealed battery according to the second embodiment, FIG. 10 is an explanatory view showing a state in which a large stress is applied to the welded-sealed battery according to the first embodiment, and FIG. It is explanatory drawing which shows the state at the time of applying a large stress to the welded sealing battery which concerns on a form. It should be noted that in FIGS.
Members having functions similar to those of the embodiment are denoted by the same reference numerals.

As shown in FIG. 9, in the sealed battery according to the second embodiment, the adhesive tape 25 is extended to the contact point between the spacer 56 and the spiral electrode body 40, except that the adhesive tape 25 extends from the first embodiment. It has the same structure as.

With the above configuration, the following operation and effect can be obtained. That is, in the sealed battery of the first embodiment, FIG.
As shown in FIG. 5, when the battery is dropped many times, and the positive electrode current collecting tab 24 is so long that the positive electrode current collecting tab 24 is loosened,
The slackened portion enters from the gap between the spacer 56 and the spiral electrode body 40. In such a state, the positive electrode current collecting tab 2
4 and the negative electrode of the spiral electrode body 40 may come into contact with each other to cause a short circuit in the battery. In particular, in the spiral electrode body 40, since the width of the negative electrode is next to that of the separator 41, the positive electrode current collecting tab 24 and the negative electrode are easily in contact with each other.

On the other hand, in the sealed battery of the second embodiment, the battery is dropped many times as shown in FIG.
Even if the positive electrode current collecting tab 24 becomes longer as the positive electrode current collecting tab 24 becomes slack, the adhesive tape 25 is present at the contact point between the spacer 56 and the spiral electrode body 40. It does not enter through the gap between the spiral electrode body 56 and the spiral electrode body 40. Therefore, it is possible to prevent the positive current collecting tab 24 from contacting the negative electrode of the spiral electrode body 40 and causing a short circuit in the battery. Further, the contact between the spacer 56 and the spiral electrode body 40 in the virtual extension of the adhesive tape 25 may be covered with an insulating member different from the adhesive tape 25 without extending the adhesive tape 25. The material of the insulating member may be the same as or different from that of the adhesive tape 25. As described above, the first and second embodiments have been described, but it is a matter of course that the present invention is not limited to these embodiments. That is, for example, the following may be performed.

(1) The adhesive tape is made of a material having an organic electrolyte resistance such as polyethylene, polyethylene terephthalate, and polyphenylene sulfide. (2) The current collecting tab is formed by the cut portion on the negative electrode side. (3) The dimensions and materials of the cores of the positive and negative electrodes are other values and materials. (4) The type of power generation element of the battery is other.

[0028]

EXAMPLES (Example 1) In Example 1, a battery manufactured by the same method as that described in the first embodiment was used. The battery fabricated in this manner is hereinafter referred to as Battery A1 of the invention.

(Embodiment 2) As Embodiment 2, the second
A battery manufactured by the same method as that described in the embodiment was used. The battery fabricated in this manner is hereinafter referred to as Battery A2 of the invention.

(Comparative Example) As shown in FIG. 14 of the prior art, a cut 1 was made without sticking the adhesive tape shown in the example.
A battery was fabricated in the same manner as in Example 1 except that a tape 107 for preventing cutting was applied so as to cover the current collecting tab 103 formed by folding back the opening 02 in the opening direction. The battery fabricated in this manner is hereinafter referred to as Comparative Battery X.

(Experiment 1) The number of defects when the impact was applied to the battery A1 of the present invention and the comparative battery X was examined. The results are shown in Table 1. The experimental conditions were such that each battery was dropped on a P tile from a height of 30 cm in a discharged state, and the number of drops was one time with each side (six sides) of the battery facing the floor. This was repeated for 30 sets, with the dropping as one set. In addition, as a criterion for determining whether or not there was a defect, a case where the resistance fluctuated by 10 mΩ or more before and after the experiment was determined to be defective.

[0032]

[Table 1]

As a result, it was confirmed that the battery A1 of the present invention did not have any failures, while the comparative battery X had all 50 failures.

This is because, in the comparative battery X, when a stress was applied to the positive electrode current collecting tab due to an impact such as dropping, the tab of the positive electrode current collecting tab was cut off in the vicinity of the welded portion. Then, as shown in FIG.
, The positive electrode core 21 on the virtual extension of the cut 23 is torn and cracks (that is, the positive electrode current collecting tab 24 becomes longer). This is considered to be because the tab of the current collecting tab 24 can be prevented from being cut. The dashed line in FIG. 12 shows the state of the positive electrode current collecting tab 24 before cracking occurs in the positive electrode core 21 (that is, before the experiment).

(Experiment 2) The number of defects when a large number of impacts were applied to the battery A1 of the present invention and the battery A2 of the present invention were examined. The results are shown in Table 2.

The experiment conditions were the same as those in Experiment 1 except that the number of drops was 300. In addition, the criterion for determining whether or not there is a defect is to disassemble the battery after the end of the experiment and visually check whether or not the squeezing phenomenon of the positive electrode current collecting tab has occurred. did.

[0037]

[Table 2]

As a result, it was confirmed that the battery A1 of the present invention had 14 defective cells, whereas the battery A2 of the present invention had no defective cells.

This is because, in the battery A1 of the present invention, since no adhesive tape exists at the contact point between the spacer and the spiral electrode body,
If the positive electrode current collecting tab becomes long enough to loosen the positive electrode current collecting tab, the slackened portion enters from the gap between the spacer and the spiral electrode body. On the other hand, in the battery A2 of the present invention, since the adhesive tape exists at the contact point between the spacer and the spiral electrode body,
This is because even if the positive electrode current collecting tab becomes longer as the positive electrode current collecting tab becomes slack, the slackened portion does not enter from the gap between the spacer and the spiral electrode body.

[0040]

As described above, according to the present description, even if vibration such as dropping of the battery is applied, the breakage of the tab can be prevented, thereby greatly improving the reliability of the sealed battery. This has the effect of being able to be improved. Further, if a reinforcing member is extended to the contact point between the spacer and the spiral electrode body, or if the contact point is covered with an insulating member different from the reinforcing member, a short circuit in the battery can be prevented. .

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a sealed battery according to a first embodiment.

FIG. 2 is a configuration diagram of a positive electrode plate used in the sealed battery according to the first embodiment.

FIG. 3 is a partially enlarged view of a positive electrode plate used in the sealed battery according to the first embodiment.

FIG. 4 is a configuration diagram of a negative electrode plate used in the sealed battery according to the first embodiment.

FIG. 5 is a diagram showing a configuration of a horizontal (horizontal) cross section of a spirally wound electrode body used in the sealed battery according to the first embodiment.

FIG. 6 is a half sectional view of a sealing lid used for the welded sealing battery according to the first embodiment.

FIG. 7 is a perspective view of a sealing lid used in the welded sealing battery according to the first embodiment as viewed obliquely from below.

FIG. 8 is an explanatory view showing a manufacturing process of the sealed battery according to the first embodiment.

FIG. 9 is a side view of a main part of the welded sealed battery according to the second embodiment.

FIG. 10 is an explanatory diagram showing a state in which a large stress is applied to the welded-sealed battery according to the first embodiment.

FIG. 11 is an explanatory diagram showing a state when a large stress is applied to the welded-sealed battery according to the second embodiment.

FIG. 12 is an explanatory view showing a state in which stress is applied to the welded sealed battery of the present invention.

FIG. 13 is an explanatory view showing a manufacturing process of a conventional sealed battery.

FIG. 14 is a partial sectional view of a conventional welded sealed battery.

FIG. 15 is a cross-sectional view showing a state in which stress is applied to a conventional sealed battery.

[Explanation of symbols]

 20: Positive electrode plate 23: Cut portion 24: Positive electrode current collecting tab 25: Adhesive tape 30: Negative electrode plate 40: Spiral electrode body 41: Separator 50: Sealing lid 60: Battery outer can

Claims (2)

[Claims] 1. A spiral electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween, a battery outer can containing the spiral electrode body, and a positive electrode plate located at the outermost periphery of the spiral electrode body. A current collector tab formed by making a substantially U-shaped cut in the exposed portion of the core of the negative electrode plate, cutting the cut out and turning the cutout toward the opening side of the battery outer can, and the opening of the battery outer can. A current collecting tab, the battery outer can and the sealing lid are welded in a state where the current collecting tab is sandwiched between the opening edge of the battery outer can and the sealing lid; In the welded sealed battery having the structure described above, the width of the current collection tab from the surface facing the spiral electrode body to the surface of the outermost core body of the spiral electrode body via the folded portion is larger than the width of the base portion of the current collection tab. A narrow reinforcing member attached Sealing the battery. 2. A spacer exists between the sealing lid and the spiral electrode body, and the reinforcing member extends to a contact point between the spacer and the spiral electrode body, or an insulating member different from the reinforcing member. The sealed battery according to claim 1, wherein the contact is covered with a member.