KR20090127809A - Battery pack - Google Patents

Abstract

PURPOSE: A battery pack is provided to reduce reactive current when a lead plate is resistance-welded while securing strength, to improve welding strength, and to be suitable for cellular phone or mobile apparatus. CONSTITUTION: A battery pack has a lead plate(5) for electric connection welded to a small battery(20). The lead plate has a protruded part(51) of which a small battery side is opened, and is welded at both positions(26) of the protruded part. The small battery comprises an injection hole and a sealing material(20) blocking up the injection hole. The sealing material is a laminate of the metal plate.

Description

Battery Pack {BATTERY PACK}

The present invention relates to a battery pack in which a lead plate for electrical connection is welded to a unit cell.

BACKGROUND ART With the recent thinning and miniaturization of battery packs, battery packs in which a positive electrode lead and a negative electrode lead are taken from a sealing body side of a unit cell, and a protection circuit and a protection element are concentrated on the sealing body side have become mainstream.

8, the whole structure of an example of a conventional battery pack is demonstrated. 8 is an exploded perspective view of an example of a conventional battery pack 100. The cell 101 seals the opening of the exterior can 102 with the sealing body 103. The injection hole of the sealing body 103 is blocked by the sealing body 104.

The lead plate 105 is welded in the vicinity of the sealing body 104 of the sealing member 103 (anode), and one end of the lead plate 107 is welded to the negative electrode terminal 106. The lead plate 105 is welded to the protection circuit 108 via the lead plate 122 (FIG. 10), and the other end of the lead plate 107 is welded to one end of the protection element 109. The other end of the protection element 109 is welded to one end of the lead plate 110, and the other end of the lead plate 110 is welded to the protection circuit 108. An insulating plate 111 is interposed between the protection circuit 108 and the sealing member 103.

By injecting resin between the sealing member 103 and the outer cover 112, the various parts on the upper part of the cell 101, the outer cover 112, and the resin are integrally molded. In FIG. 8, the integrally molded resin 113 is shown separately for convenience of illustration. In the completed state of the battery pack 100, the integrally molded resin 113 is between the upper portion of the cell 101 and the exterior cover 112, the above-mentioned various components are included in the interior of the integrally molded resin 113 It becomes.

The can bottom cover 114 is attached to the lower part of the cell 101 via the double-sided tape 115. The label 116 is attached to the entire circumference of the cell 101.

Next, the welding of the lead plate 105 is demonstrated using FIG. 9, FIG. 9 is a perspective view showing a state of welding of the lead plate 105. The sealing body 103 is usually formed of aluminum or an aluminum alloy, and the lead plate 105 is usually formed of nickel or a nickel alloy. As described above, when the sealing member 103 and the lead plate 105 are formed of different metals, laser welding is used instead of resistance welding. Arrow 120 in the figure indicates the irradiation direction of the laser light. Table 121 shows the welding position.

In order to reliably bond the sealing body 103 and the lead plate 105 by laser welding, welding of many points is needed as shown in FIG.

10 is a perspective view illustrating welding of the lead plate 105 and the lead plate 122. 8 is a perspective view of the cell 101 viewed from the back side. Arrow 123 in the figure shows the pressing direction of the electrode. Table 124 indicates the welding position.

Both lead plates 105 and 122 are normally formed of nickel or a nickel alloy, and are the same kind of metal. For this reason, resistance welding can be used for both joining, and a welding point also becomes enough for one point.

Patent Documents 1 and 2 below describe that a cap plate (sealing body) that is a dissimilar metal and a lead plate are bonded by laser welding.

On the other hand, in FIG. 3 of following patent document 3, the structure which joined the sealing plate of the nickel metal plate and the lower part aluminum metal plate to the cap plate (sealing body) is described. According to this structure, the same type metal contact | connects the cap plate formed from aluminum, the (sealing body), and the lower part of a sealing plate, and weldability improves. Similarly, the upper part of the lead plate formed from nickel and the sealing plate formed from the nickel metal plate is brought into contact with the same metal, thereby improving weldability.

[Patent Document 1]

Japanese Patent Application Laid-Open No. 2005-285758

[Patent Document 2]

Japanese Patent Application Laid-Open No. 2005-285761

[Patent Document 3]

Japanese Patent Application Laid-Open No. 2006-12829

Therefore, in the structure of FIG. 8, the lead plate 104 can be resistance-welded to a sealing plate by interposing the sealing plate of patent document 3 between the lead plate 105 and the sealing body 103. FIG.

However, in the case of resistance welding with overlapping plates, there have been the following problems. When a pair of electrodes are brought into contact with both ends of the lead plate 105 and energized, a current flows through only the lead plate 105 without a sealing plate between the pair of electrodes. This current is a reactive current that contributes little to welding. For this reason, when the amount of reactive current increases, there exists a problem that predetermined welding strength is not obtained.

On the other hand, when the cross-sectional area of the lead plate 105 is small, the amount of reactive current decreases, but the strength also decreases. In this structure, when the resin is integrally formed on the lead plate 105, the bonding strength with the resin is also weakened.

The present invention solves the conventional problems as described above, and an object thereof is to provide a battery pack having a lead plate suitable for resistance welding while securing strength.

In order to achieve the above object, the battery pack of the present invention is a battery pack for welding an electrical connection lead plate to a cell, wherein the lead plate forms a convex portion with the cell side open. The said welding is performed in the position which interposes a convex shape part.

According to the present invention, a battery pack having a lead plate suitable for resistance welding while securing strength is obtained.

The lead plate according to the battery pack of the present invention increases resistance by forming a convex portion. Thereby, reactive current at the time of resistance welding of a lead plate can be reduced, ensuring strength, and welding strength can be improved.

In the battery pack of the present invention, it is preferable that the resin is molded integrally with the unit cell, and the lead plate is inside the molded resin. According to this configuration, when an external force is applied to peel the integrally molded resin from the cell, the convex portion of the lead plate becomes a resistance, and the convex portion acts to prevent peeling of the integrally molded resin 13. Thereby, the installation strength with respect to the unit cell of integrally molded resin can be improved.

In addition, the cell includes a liquid injecting hole and a sealing body for blocking the liquid injecting hole, the sealing body is a laminate of metal plates, and the first metal plate and the lead plate forming the uppermost layer of the sealing body are welded, The 2nd metal plate which forms the lowest layer of the said sealing body and the said cell are welded, The said 1st metal plate is formed with the metal of the same kind as the said lead plate, The said 2nd metal plate is the said 2nd among the said cells It is preferable that the metal plate is formed of the same metal as the welded portion. According to this structure, the weldability of a lead plate and a sealing body becomes favorable.

Moreover, it is preferable that the said lead plate has the part which narrowed in width. According to this structure, the reactive current at the time of resistance welding a lead plate can further be reduced.

EMBODIMENT OF THE INVENTION Hereinafter, one Embodiment of this invention is described in detail, referring drawings. 1 is an exploded perspective view of a battery pack according to an embodiment of the present invention. A schematic structure of the battery pack 1 will be described with reference to FIG. 1. The unit cell 2 seals the opening of the exterior can 3 containing the power generating element with the sealing member 4. The unit cell 2 is, for example, a rectangular lithium ion battery and is used for a cellular phone, a mobile device, and the like.

The lead plate 5 is welded to the sealing body 20. The sealing body 20 seals the injection hole which injects electrolyte solution. In this embodiment, the sealing body 20 has the structure which laminated | stacked the dissimilar metal plate in order to improve the weldability with the lead plate 5. The detail of the sealing body 20 is demonstrated using FIG. 2 from behind.

One end of the lead plate 7 is welded to the negative electrode terminal 6. The other end of the lead plate 7 is welded to one end of the protective element 9. The lead plate 5 is welded to the protection circuit 8 via the lead plate 33 (FIG. 5). The other end of the protection element 9 is welded to one end of the lead plate 10, and the other end of the lead plate 10 is welded to the protection circuit 8. An insulating plate 11 is interposed between the protective circuit 8 and the sealing member 4.

By injecting resin between the sealing member 4 and the outer cover 12, the various parts on the upper part of the unit cell 2, the outer cover 12, and the resin are integrally molded. In FIG. 1, the integral molding resin 13 is shown separately for convenience of illustration. In the finished state of the battery pack 1, the integrally molded resin 13 is between the upper part of the cell 2 and the exterior cover 12, and the above-mentioned various parts are contained in the integrally molded resin 13 inside. It becomes.

The can bottom cover 14 is attached to the lower part of the unit cell 2 via the double-sided tape 15. A label 16 is attached to the entire circumference of the cell 2.

The battery pack 1 according to the present embodiment has a different structure between the lead plate 5 and the sealing body 20 as compared with the conventional battery pack 101 of FIG. 8. This difference will be described below.

FIG. 2 is an enlarged view of the seal 20 shown in FIG. 1. (A) is a perspective view, (b) is sectional drawing in the AA line of FIG. The sealing body 20 is obtained by compressing and laminating an aluminum plate 21 formed of aluminum or an aluminum alloy and a nickel plate 22 formed of nickel or a nickel alloy. As shown in Fig. 2 (b), the aluminum plate 21 forms a convex portion 21a, and the convex portion 21a is fitted into the liquid inlet 24 of the sealing member 4 so that the liquid inlet ( 24) It is sealed.

The sealing body 20 is joined to the sealing body 4 by welding the aluminum plate 21 to the sealing body 4. Thereby, the welding part 23 is formed in the whole periphery of the aluminum plate 21. As shown in FIG. Both the sealing body 4 and the aluminum plate 21 are formed with the same metal of aluminum or an aluminum alloy, and weldability is favorable.

In addition, although the sealing body 20 shows the example which made the metal plate two layers in FIG.2 (a), (b), the metal plate may be further interposed between the two metal plates.

3 is a perspective view showing a state of welding of the lead plate 5. Resistance welding is started on the nickel plate 22 of the sealing body 20 in the state which the lead plate 5 was overlapped. The arrow 25 has shown the contact direction of an electrode, and the mark 26 has shown the welding part. The lead plate 5 and the nickel plate 22 of the upper part of the sealing body 20 are all formed with the same metal of nickel or nickel alloy, and the weldability of resistance welding is favorable.

FIG. 4 is an enlarged view showing the side surface of the lead plate 5, and corresponds to the view seen from the arrow B direction in FIG. 3. As shown in FIG. 4, at the time of resistance welding of the lead plate 5, a pair of electrodes 30 are pressed against the surface of the lead plate 5 mounted on the nickel plate 22. By energizing in this state, the lead plate 5 can be welded at two points.

At the time of resistance welding, the electric current shown by the broken line 31 and the electric current shown by the broken line 32 generate | occur | produce. The electric current shown by the broken line 31 passes the lead plate 5 through the plate thickness direction from one electrode 30, passes through the nickel plate 22, and passes the lead plate 5 through the plate thickness direction again. This is the current flowing to the other electrode 30. The current shown by the broken line 32 is a current flowing from one electrode 30 through the lead plate 5 to the other electrode 30.

Since the electric current shown by the broken line 31 is the electric current which flows in both the lead plate 5 and the nickel plate 22, it becomes an effective electric current which contributes to welding. On the other hand, since the current shown by the broken line 32 does not flow through the nickel plate 22, it becomes an reactive current which hardly contributes to welding.

In order to increase the welding strength, it is necessary to make the amount of reactive current flowing through the lead plate 5 as small as possible. For this purpose, it is conceivable to increase the resistance of the lead plate 5. The resistance R of the conductor (Ω) can be represented by the following formula (1).

R = ρ × (L / S)

In equation (1), p is the electrical resistivity (Ωm), which is a coefficient, L is the conductor length (m), and S is the conductor cross-sectional area (m 2).

According to Formula (1), in order to enlarge resistance R, conductor length L may be enlarged and conductor cross-sectional area S may be made small. Considering the configuration in which the conductor length L is enlarged, when the length of the lead plate 5 is merely lengthened in the width direction (the arrow C direction in Fig. 4) of the unit cell 2, the welding interval is widened. In this case, the welding interval in the nickel plate 22 also increases, and the resistance of the nickel plate 22 also increases.

On the other hand, if the increase in the length is ensured in the height direction (arrow D direction in FIG. 4) of the cell 2, the lead between the pair of electrodes 30 is maintained while maintaining the distance between the pair of electrodes 30. The resistance of the plate 5 can be made large. The lead plates 5 shown in FIGS. 3 and 4 form convex portions 51 open to the cell 2 side. This increases the length along the surface of the lead plate 5 without increasing the distance between the pair of electrodes 30 while ensuring strength.

Therefore, the amount of reactive current shown by the broken line 32 is reduced compared with the structure using the flat lead plate which does not form the convex part 51. FIG. As the reactive current represented by the broken line 32 decreases, the effective current represented by the broken line 31 increases, so that the welding strength also increases.

5 is a perspective view illustrating welding of the lead plate 5 and the lead plate 33. This figure is the perspective view which looked at the lead plate 5 from the back side in FIG. Although the lead plate 33 is shown as a single piece for convenience of illustration, the lead plate 33 is a component of the protection circuit 8. For this reason, when the lead plate 33 is welded to the lead plate 5, the protection circuit 8 is connected to the lead plate 5.

In FIG. 5, if the lead plate 33 is made of the same metal material as the lead plate 5, resistance welding can be used for the joining of both, and the welding score is also sufficient as one point. Arrow 34 indicates the pressing direction of the electrode, and the mark 35 indicates the welding position. This is the same also in the conventional FIG. That is, according to the present embodiment, the lead plate 5 can be welded to the side of the cell 2, and the protection circuit 8 can be subjected to resistance welding in the same manner as before.

6 is an enlarged view showing the side surface of the resin molded part. 6 shows a state in which a protective circuit 8 is provided and an exterior cover 12 (see FIG. 1) is provided thereon. Fig. 6 shows the state before the resin injection, but shows the integrally molded resin 13 by the two-dot chain lines.

Before the resin injection, the exterior cover 12 is merely mounted on the protection circuit 8 and is not firmly fixed to the cell 2. By integrally molding the resin injected between the outer cover 12 and the cell 2 with the outer cover 12 and the cell 2, the outer cover 12 passes through the integral molding resin 13, It is firmly fixed to the cell 2.

In this case, the lead plate 5 is also included in the integrally molded resin 13. Compared with the structure using the flat lead plate which does not form the convex part 51, this structure becomes the coupling force with the integrally molded resin 13 strengthened.

More specifically, when an external force is applied to peel the integrally molded resin 13 from the cell 2, the convex portion 51 of the lead plate 5 becomes a resistance, and the convex portion 51 is integrally molded. It serves to hinder the peeling of the resin 13. For this reason, by using the lead plate 5 provided with the convex part 51, the installation strength with respect to the unit cell 20 of the integrally molded resin 13 can be improved.

As the external force for peeling the integrally molded resin 13 from the cell 2, an external force for pulling the integrally molded resin 13 in the vertical direction and an external force for twisting the integrally molded resin 13 can be considered.

Moreover, since the convex part 51 can be arrange | positioned in the filling space of resin, it is possible to form so that it may not interfere with other accessory parts, and does not raise the height of a filling space.

7 is a perspective view illustrating another example of the lead plate 5. In the lead plate 5 shown in this figure, the notch 52 is provided in the convex part 51. The section in which the notch 52 is provided becomes small in cross section. That is, the example of FIG. 7 corresponds to the example which made conductor length L large and conductor cross-sectional area S small in said Formula (1). Therefore, according to this configuration, the resistance R can be further increased, and the reactive current can be further reduced.

On the other hand, since the notch 52 is formed, the strength of the lead plate 5 is lowered as compared with the configuration of FIGS. 3 to 6, so that the installation strength of the unit cell 20 of the integrally molded resin 13 is improved. The effect is small. Therefore, whether or not the configuration of FIG. 7 is used, or how much the cross-sectional area is to be set in the configuration of FIG. 7, improves the welding strength due to the reduction of the reactive current and the unit cell 20 of the integrally molded resin 13. What is necessary is just to consider the degree of fall of the installation strength with respect to).

Although the example which formed the notch 52 was shown in FIG. 7, the part which narrowed the width | variety of the lead plate 5 may be sufficient, and what provided the hole in the convex part 51 may be sufficient. The part which narrowed the width | variety (5) should just be provided between the electrodes 30, and may be provided in the side surface, not limited to the upper surface of the convex part 51 like the example of FIG.

In addition, in the said embodiment, although the convex part 51 of the lead plate 5 demonstrated the side surface as an example of rectangular shape, it is not limited to this, What is necessary is just the convex part opened to the cell 2 side. For example, the side surface shape may be an inverted V shape, a semicircle shape, a triangular shape, or a trapezoidal shape.

As mentioned above, according to this invention, since the battery pack provided with the lead plate suitable for resistance welding is obtained, ensuring intensity | strength, this invention is useful as a battery pack used for a mobile telephone or a mobile device, for example. .

1 is an exploded perspective view of a battery pack according to an embodiment of the present invention;

2 is an enlarged view of the seal 20 shown in FIG. 1, (a) is a perspective view, (b) is a sectional view taken along the line AA of (a),

3 is a perspective view showing a state of welding of a lead plate according to one embodiment of the present invention;

4 is a side view of a lead plate according to one embodiment of the present invention;

5 is a perspective view showing welding of lead plates according to one embodiment of the present invention;

6 is an enlarged side view showing a resin molded part according to one embodiment of the present invention;

7 is a perspective view showing a lead plate according to another embodiment of the present invention;

8 is an exploded perspective view showing an example of a conventional battery pack;

9 is a perspective view showing a state of welding of a conventional lead plate,

It is a perspective view which shows the welding of the conventional lead plates.

※ Explanation of code for main part of drawing

1: Battery Pack 2: Battery

5: lead plate 13: integrally molded resin

24: injection hole 20: sealing body

21: aluminum plate 22: nickel plate

51: convex shape 52: notch

Claims (4)

A battery pack for welding a lead plate for electrical connection to a cell, The lead plate has a convex shape with the cell side open. The battery pack is welded to a position where the convex portion is interposed therebetween. The method of claim 1, A resin pack is integrally formed with the unit cell, and the lead plate is inside the molded resin. The method according to claim 1 or 2, The cell has a liquid injection hole and a sealing body that closes the liquid injection hole. The said sealing body is what laminated | stacked the metal plate, A first metal plate forming the uppermost layer of the sealing body and the lead plate are welded, a second metal plate forming the lowermost layer of the sealing body and the cell are welded, The first metal plate is formed of a metal of the same type as the lead plate, and the second metal plate is formed of a metal of the same type as the portion of the cell where the second metal plate is welded. . The method according to any one of claims 1 to 3, The lead plate, the battery pack, characterized in that the narrowed portion.

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