JP2002050339A - Welding electrode for battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve welding treatment efficiency and realize a stable welding for a welding electrode used in welding a collector at an end of a cylindrical electrode group formed by winding positive and negative electrodes around through a separator. SOLUTION: The welding electrode for the battery is for welding a tabular collector with a plurality of slits formed in a radial pattern, and comprises a pair of welding parts 60, 61, capable of simultaneously welding both side edge parts of the two slits located in opposite angle passing the center of the collector and connecting parts 62, 63 for fixing the welding parts to welding heads, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding electrode for a battery, and more particularly, it is possible to reduce the number of weldings when welding a current collector to a secondary battery used as a large current drive power supply. The present invention relates to a welding electrode having excellent welding stability.

[0002]

2. Description of the Related Art In recent years, attempts have been made to use a secondary battery such as a nickel-metal hydride secondary battery as a large-current drive power source for a hybrid vehicle or an electric tool. Such a secondary battery generally has a structure in which an electrode group formed by winding a sheet-like positive electrode body and a sheet-like negative electrode body via a separator is loaded into a cylindrical outer can. Have.

[0003] As a current collecting structure of such a battery, for example, in the case of a general-purpose small secondary battery, since the takeout current is small, the outermost periphery of the above-mentioned electrode group is brought into contact with an outer can as a negative electrode terminal. Collect current on the negative electrode side.
On the other hand, it is common to collect the current on the positive electrode side by connecting a tab protruding from the positive electrode to a sealing member insulated from the outer can.

However, a secondary battery which requires a large current output has a large take-out current. Therefore, current collectors for a positive electrode and a negative electrode are respectively attached to both ends of a wound electrode group by means such as resistance welding. It is common to connect. FIG. 6 shows a current collector 1 used for such resistance welding.
This is an example in which a plurality of, here eight slits a to h are formed radially on a substantially circular flat plate. These slits are opposed to each other.
The pieces, ie, a and e, b and f, c and g, and d and h are located in a straight line passing through the center.

Further, the slits a to h of the current collector 1
As shown in FIG. 7, protrusions or burrs 1a are formed along both longitudinal edges of each slit in order to increase resistance during welding. When the current collector is welded to the electrode group, as shown in FIG. 8, the current collector 1 is attached to an end of a roll-shaped electrode group 2 wound in a cylindrical shape.
Are arranged so that the burrs 1a are in contact with the ends 2a and 2b of the electrode group 2, and then the both sides are welded by applying current to both side edges of the slits a to h.

Conventionally, a welding electrode 3 used for welding such a current collector 2 has a slit a as shown in FIGS.
And a pair of welds 30, 31 having contact portions 30a, 31a slightly shorter than the length of
Connecting portions 32 and 33 for supporting the base 31 in parallel at a distance of about the width of the slit. Then, as shown in FIG. 10, the connecting portions 32 and 33 are connected and fixed to arms 41 and 42 provided at the lower end of the welding head 4.

Conventionally, in this welding step, as shown in FIG. 11, contact portions 30a, 30a of the welding electrode 3 are provided on both side edges of the slits a to h of the current collector 1 placed at the end of the electrode group 2. 31a
Then, pressure is applied from the welding head 4 and power is supplied to the welding electrode 3 from a power source (not shown) to perform resistance welding. For example, when welding the current collector shown in FIG. 6, eight welding operations are required.

[0008]

However, when the conventional welding electrode as described above is used, it is necessary to perform welding by the number of slits, so that the cost and space of the welding equipment accompanying the increase in the number of weldings are increased. There is a problem that the increase of unavoidable.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a structure in which a positive electrode and a negative electrode are wound radially on both ends of a group of electrodes with a separator interposed therebetween. A welding electrode for welding a flat current collector having a plurality of slits formed therein, wherein the welding electrode has two slits positioned diagonally through the center of the current collector. Provided are a pair of welded portions capable of welding both side edges of the welded portion at the same time, and a connecting portion for fixing each of the welded portions to a welding head.

In the above configuration, the connection portion includes a holder portion, a coupling shaft that rotatably supports the pair of welding portions with respect to the holder portion, and the holder portion to the welding head. It is preferable that the device has a connecting portion for fixing.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the welding electrode of the present invention will be described with reference to the drawings. FIG. 1 shows a welding electrode 5 of a fixed welding part type. The welding electrode 5 is composed of a pair of welding parts 50 and 51 and connecting parts 52 and 53 which support these welding parts 50 and 51 in parallel at a predetermined interval. Be composed. These connecting portions 52 and 53 are attached to a welding head (not shown), similarly to the conventional welding electrode described above.

Each of the welded portions 50, 51 has, for example, contact portions 50a, 50b and 51a, 51b corresponding to a set of slits formed on the current collector 1 shown in FIG. (Only 51a is shown) is formed to protrude. Then, both side edges of the slit a can be welded simultaneously by the contact portions 50a and 51a, and both side edges of the slit e can be welded by the contact portions 50b and 51b.

Further, since two slits such as slits b and f, slits c and g, and slits d and h can be sequentially welded, the number of times of welding is reduced to one half of the conventional number, and the manufacturing efficiency is reduced. Significantly improved. FIGS. 2 and 3 show a welding electrode movable following type welding electrode as another configuration of the welding electrode of the present invention.
61 and connecting portions 62 and 63.

Each of the welded portions 60 and 61 corresponds to, for example, a set of slits formed on the current collector 1 shown in FIG. The contact portions 60a, 60b and 61a, 61b (61a
(Shown only). And the contact part 60
a and 61a, the both side edges of the slit a
And 61b can weld both side edges of the slit e at the same time.

The connecting portions 62 and 63 are provided on holder portions 6 disposed on side surfaces 60c and 61c of the welding portions 60 and 61, respectively.
4, 65, and each holder 6
It is composed of coupling shafts 66 and 67 that rotatably support 0 and 61 and coupling portions 68 and 69 attached to the upper ends of the holder portions 64 and 65, respectively. As in the case of the above-mentioned fixed welding portion welding electrode 5, the connecting portions 68 and 69 are fixed to a welding head (not shown).

When the current collector 1 is welded using such a welding electrode 6, as shown in FIG. 4, the current collector 1 is placed on the end of the electrode group 2, and The welding electrodes are lowered from the contact portions 60a, 60 of the welding portions 60, 61.
b, 61a, 61b are slits of the current collector 1, for example, a, e
Contact both side edges of Generally, since the electrode group 2 is formed by winding a positive / negative electrode body and a separator, the upper end surface is not necessarily flush with the plane. Therefore, when the contact portion of the welding electrode 6 is brought into contact with the upper end surface of the electrode group, the current collector 1 is affected by the influence, so that there are four contact portions 60a, 60b, 61a, 61b.
Do not always contact the side edges of the slit at the same time.

Furthermore, the current collector 1 itself also has warpage during manufacturing,
There is a curvature and the flatness is low in some cases. As described above, when the end surface of the electrode group 2 or the upper surface of the current collector 1 is not flat, each of the contact portions 60a, 60b, 61a,
One side hit occurs at 61b. At one side of such an electrode contact portion, the pressing force to the slit portion is applied unevenly,
This is a factor that increases the splash during welding. As a result, stable welding is hindered.

Specifically, when the above-mentioned welding electrode 6 is used, as shown in FIG. 5, for example, when the welding portion 60 side is viewed, the contact portions 60a, 60b of the welding portion 60 are formed on the current collector 1.
When the contact is made, the contact portion 60a contacts the slit side edge of the current collector 1, but the current collector 1 is warped, so that the contact portion 60b and the upper surface of the current collector 1 May have a gap h.

However, when the welding electrode 6 is used,
As more pressure is applied to the holder portion 64 from the welding head via the connecting portion 68, the welding portion 60 rotates clockwise around the coupling shaft 66 independently of the holder portion 64, and as a result, the contact The portion 60b contacts the current collector 1.
At this time, since the pressing force is also constantly applied to the contact portion 60a, the contact portion 60a is prevented from being separated from the current collector 1. Such an operation is individually performed for the welded portion 61, and the contact portions 61a and 61b of the welded portion 61 are provided.
Also contact the current collector 1 without contact, so that even welding can be performed even during subsequent welding.

As described above, the welding portions 60,
Numeral 61 indicates the state of the end faces of the current collector 1 and the electrode group 2,
Since the movable follow-up is possible, there is an advantage that the pressing force at the time of welding is uniformly applied to all the contact portions, and the welding can be performed in a stable state.

[0021]

EXAMPLE A movable tracking type welding electrode 6 shown in FIG. 2 was produced. 2 m width of the contact portions 60a, 60b, 61a, 61b
m, length 6-8mm, thickness 0.5mm, diameter about 3
Resistance welding was performed on each slit side edge of the current collector 1 having 0 mm and a slit length of 5 to 8 mm. The diameter of the end face of the electrode group 2 was approximately 30 to 33 mm.

As a result, the current collector welding processing capacity is 15 pieces / minute, and welding can be performed at twice the speed as compared with the case where the conventional welding electrode shown in FIG. 11 is used. It became. When such a welding process was performed on 50 electrode groups, no welding failure occurred in 0 electrodes.

Further, the same welding as described above was carried out using the welding electrode of the fixed type shown in FIG. As a result, the processing capacity was the same as that of the above-mentioned movable following type welding electrode, but there were two or three out of 50 electrodes in which poor welding occurred. From the above, the welding electrode of the present invention, compared with the conventional welding electrode, the welding processing capacity is significantly improved, further,
Among the welding electrodes of the present invention, in particular, the welding portion movable following type can perform stable welding regardless of the flatness of the current collector and the end face of the electrode group as compared with the welding portion fixed type. It was found to be more useful.

[0024]

As is apparent from the above description, according to the battery welding electrode of the present invention, a plurality of slit portions of a radially formed current collector can be welded two at a time. Possible and processing capacity is greatly improved. Furthermore, since the welding portion is of a movable following type, stable weldability can be ensured, so that the yield rate in the manufacturing process is improved, and the industrial value is great.

[Brief description of the drawings]

FIG. 1 is a perspective view of a welding-fixed welding electrode according to an embodiment of the present invention.

FIG. 2 is a perspective view of a welding portion movable following type welding electrode according to another embodiment of the present invention.

FIG. 3 is an end view of a welding portion movable following welding electrode according to another embodiment of the present invention.

FIG. 4 is a conceptual diagram showing a process of welding a current collector to an electrode group end using a movable following welding electrode.

FIG. 5 is a conceptual diagram for explaining the operation of a movable following welding electrode.

FIG. 6 is a top view of a current collector in which a plurality of slits are formed.

FIG. 7 is a conceptual diagram for explaining protrusions (burrs) on a slit side edge of a current collector.

FIG. 8 is a perspective view showing a positional relationship between an electrode group and a current collector.

FIG. 9 is a perspective view of a conventional battery welding electrode.

FIG. 10 is a conceptual diagram showing a state where a conventional welding electrode is attached to a welding head.

FIG. 11 is a conceptual diagram showing a process of welding a current collector to an end of an electrode group using a conventional welding electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current collector 1a Projection (burr) 2 Electrode group 4 Welding head 5 Welding electrode (fixed welding part) 50, 51 Welding part 50a, 50b, 51a, 51b Contact part 52, 53 Connection part 6 Welding electrode (welding) 60, 61 Welded portions 60a, 60b, 61a, 61b Contact portions 62, 63 Connecting portions 64, 65 Holder portions 66, 67 Coupling shafts 68, 69 Connecting portions

Claims (2)

[Claims] 1. A flat current collector having a plurality of slits formed radially at both ends of an electrode group formed by winding a positive electrode body and a negative electrode body via a separator. A welding electrode, wherein the welding electrode is capable of simultaneously welding both side edges of two diagonally located slits passing through the center of the current collector; A welding electrode for a battery, comprising: a connection portion for fixing to a welding head. 2. The connecting part includes a holder, a coupling shaft that rotatably supports the pair of welding parts with respect to the holder, and a connection for fixing the holder to the welding head. The welding electrode for batteries according to claim 1, further comprising: