JP2018056095A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery pack capable of improving battery performance by giving flexibility to a joint portion with a secondary battery by using a flexible connection member with a low manufacturing cost.SOLUTION: Disclosed battery pack includes: plural cylindrical secondary batteries; and a connection member which connects the plural cylindrical secondary batteries, in which the connection member has flexibility.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an assembled battery used for in-vehicle use.

In recent years, secondary batteries with large capacity (Wh) have been developed as power sources for hybrid electric vehicles and pure electric vehicles, among which lithium-ion secondary batteries with high energy density (Wh / kg) have attracted attention. Yes.
In a cylindrical lithium ion secondary battery, a positive electrode foil coated with a positive electrode active material, a negative electrode foil coated with a negative electrode active material, and a cylindrical storage element wound by overlapping separators for insulating each other The battery is accommodated in a can and electrically connected to a lid that also serves as a positive electrode terminal and a battery can that also serves as a negative electrode terminal. Then, an electrolytic solution is injected from the opening of the battery can, the opening of the battery can is closed with a lid, and the battery can is sealed by caulking to produce a secondary battery.

  Then, a plurality of the above-described cylindrical lithium ion secondary batteries are connected in series or in parallel to produce an assembled battery. For this purpose, the bus bar is connected to the positive and negative terminals of each battery by welding. For example, when a cylindrical battery is connected in series in the axial direction to form a battery module composed of one battery group of a predetermined length, the connection of the cylindrical battery is, for example, circular on the positive terminal side of the battery. The spot-shaped member is spot-welded, and the bottom of the can, which is the negative electrode terminal of another battery, is inserted into the dish-shaped member. Also provided is a battery module characterized in that a battery group formed by connecting a plurality of cylindrical batteries in series in the axial direction is supported by an electrically insulating member attached in the longitudinal direction of the side surface. Has been. (Patent Document 1)

Japanese Patent Laid-Open No. 2000-173666

However, when it is a connecting member that does not have flexibility as described in (Patent Document 1), stress or the like due to unexpected vibration / impact or thermal expansion difference is directly applied to the joint,
In order to prevent the occurrence of cracks at the joints and breakage of the joints, it is necessary to use another member for reinforcement. Cost may increase. In order to address these problems, the present application aims to provide an assembled battery with improved battery performance by suppressing the stress and manufacturing cost on the joint with the secondary battery by giving the connecting member flexibility. Yes.

In order to solve the above-described problems, the present invention provides a battery pack having a plurality of cylindrical secondary batteries and a connection member that connects the plurality of cylindrical secondary batteries, wherein the connection member has flexibility.

In the present invention, in the assembled battery having a plurality of cylindrical secondary batteries and a connecting member for connecting the plurality of cylindrical secondary batteries, the assembled battery has improved battery performance because the connecting member has flexibility. Can be provided.

External perspective view of module (assembled battery) Exploded perspective view of module Busbar perspective view Perspective view of flexible part of serial bus bar Assembly drawing of flexible part of serial bus bar of embodiment 1 The perspective view of the sheet-metal part of the serial bus bar of Example 1 Assembly drawing of serial bus bar of embodiment 1 Assembly drawing of serial bus bar of embodiment 1 The perspective view of the bus bar for series of Example 1. Assembly drawing of serial bus bar of embodiment 1 The perspective view and assembly drawing of the bus bar for parallel of Example 1 Assembly drawing of bus bar for series and battery of Example 1 Assembly drawing of bus bar for series and battery of Example 1 Assembly drawing of bus bar for series and battery of Example 1 Plan view and side view of serial bus bar and battery assembly of Example 1 Assembly drawing of parallel busbar and battery of Example 1 The perspective view of the bus bar of Example 2. The perspective view of the bus bar for series of Example 3 The perspective view of the bus bar for parallel of Example 3 The perspective view of the connection of the bus-bar of Example 4 and a cylindrical secondary battery

Hereinafter, examples will be described with reference to FIGS.
The present invention is a battery pack (hereinafter referred to as a module) having a plurality of cylindrical secondary batteries and a connection member for connecting the plurality of cylindrical secondary batteries, and the connection member has a flexible structure.

Example 1
FIG. 1 is an external perspective view of a module 100 that is a secondary battery module.
As shown, the module 100 includes a cylindrical secondary battery 101, a case 102, a case fixing screw 103 (not shown), a series bus bar 104, and a parallel bus bar 105. A plurality of cylindrical secondary batteries 101 are combined and housed in a case 102 divided vertically, and fixed with case fixing screws 103.

FIG. 2 is an exploded perspective view of the module 100.
The plurality of cylindrical secondary batteries 101 are arranged such that the axial directions of the cylindrical secondary batteries 101 face each other. The plurality of cylindrical secondary batteries arranged in the axial direction are further arranged in a direction orthogonal to the axial direction. The arrangement in the direction orthogonal to the axial direction may be on a plane as shown in FIG. 2 or may be arranged three-dimensionally.
In the axial direction of adjacent cylindrical secondary batteries 101, each positive electrode terminal and negative electrode terminal are connected via a bus bar 104 (series bus bar). The bus bar 104 is welded to the positive electrode terminal 101a of each cylindrical secondary battery 101 by, for example, TIG (Tungsten Inert Gas) welding.

  Moreover, the direction (parallel direction) orthogonal to the axial direction of the adjacent cylindrical secondary battery 101 is further connected via the bus bar 105 (parallel bus bar).

The bus bar 104 and the bus bar 105 are respectively welded to the negative electrode terminal of the cylindrical secondary battery 101 by resistance welding, for example. The material of the case 102 is, for example, a resin such as polybutylene terephthalate or polypropylene. The material of the case fixing screw 103 is, for example, a steel material such as SWCH, stainless steel, aluminum, or the like. Busbar 104, 105
The material is, for example, copper such as C1020 or aluminum.

FIG. 3A is a perspective view of the bus bar 104.
The bus bar 104 is a member that connects the positive electrode terminal and the negative electrode terminal of the adjacent cylindrical secondary battery 101. The bus bars 104 may be further connected via a bus bar 105. The bus bar 104 includes a sheet metal part 104b positioned between the positive electrode terminal and the negative electrode terminal of the adjacent cylindrical secondary battery, and protrudes from the sheet metal part 104b to the negative electrode terminal of the adjacent cylindrical secondary battery. And a flexible portion 104a. The bus bar 104 and the cylindrical secondary battery 101 are electrically connected by welding the flexible portion 104a and the sheet metal portion 104b provided on the bus bar 104 to the negative terminal 101d and the positive terminal 101a of the cylindrical secondary battery 101, respectively. To do. Furthermore, the sheet metal portion 104b of the bus bar 104 has a convex portion, and the cylindrical secondary battery 101 is joined by welding in a state of being in contact with the convex portion, thereby forming a joint portion 101c (not shown). Since the flexible portion 104a has flexibility, even if the plurality of cylindrical secondary batteries 101 connected in series are vibrated, an impact can be absorbed by this portion. In addition, the flexible portion 104a has a curved portion, and the shock can be absorbed even when the curved portion is bent.

FIG. 3B is a perspective view of the bus bar 105.
Cylindrical secondary battery 101 has a positive electrode terminal provided on one side in the axial direction and a negative electrode terminal provided on the other side in the axial direction, and bus bar 105 includes a plurality of cylindrical secondary batteries adjacent in the parallel direction. The negative terminals of the secondary battery 101 are connected to each other. The negative electrode terminal of the cylindrical secondary battery 101 reaches the side surface of the battery, and the bus bar 105 has a shape along the negative electrode terminal that reaches the side surface. In FIG.3 (b), the bus-bar 105 has an arch-shaped part as a location connected to a negative electrode terminal, and the adjacent negative electrodes are electrically connected by having the part (connection part) which connects this arch-shaped location. The Since the bus bar 105 has flexibility, even if the plurality of cylindrical secondary batteries 101 connected in series are vibrated, an impact can be absorbed at this portion. In particular, the influence of the positional deviation between the cylindrical secondary batteries 101 can be reduced because the connecting portion has flexibility.

FIG. 4 is a perspective view of the flexible portion 104a.
The flexible portion 104a is fixed and electrically connected by overlapping a plurality of thin plate-like leads 104a-1, 2,... N and joining the end portions 104c and 104d respectively. An example of the bonding method is ultrasonic bonding.

FIG. 5 is an exploded perspective view of the flexible portion 104a.
FIG. 6 is a perspective view of the sheet metal portion 104 b of the serial bus bar 104.
The sheet metal portion 104b is provided with a long hole 104b-2 serving as a gas flow path when gas is discharged from the cylindrical secondary battery 101, and is connected to the positive electrode terminal 101a of the cylindrical secondary battery 101. Two convex portions are provided. Moreover, it has the terminal part 104b-3 for connecting with the flexible part 104a. The terminal portion 104b-3 is provided so as to protrude in an L shape from the flat sheet metal portion 104b.

FIG. 7 is a view showing a state when the flexible portion 104a is joined to the sheet metal portion 104b.
The end portion 104c of the flexible portion 104a is overlaid on the terminal portion 104b-3, is fixed on the anvil 107 of the ultrasonic welder, is pressed and vibrated with a horn 106, and thereby the flexible portion 104a and the sheet metal portion 104b. Are ultrasonically bonded (FIG. 8). The flexible portion 104a may be bent in advance to join a plurality of cylindrical secondary batteries, or may be bent at the time of joining (FIG. 9).

As described above, the end portions 104c and 104d of the flexible portion 104a are joined in advance as shown in FIG. 10 and joined to the sheet metal portion 104b. However, the present invention is not limited to this. For example, the leads 104a-1, 2, ... A plurality of N are stacked and placed on the anvil 107 of the ultrasonic welder together with the terminal portion 104b-3 of the sheet metal portion 104b, fixed with a jig or the like, and pressurized and vibrated by the horn 106, thereby being flexible portion 104a. Alternatively, a method of ultrasonic bonding the sheet metal portion 104b may be used.

FIG. 11A is a perspective view of the parallel bus bar 105, and FIG.
The bus bar 105 is fixed and electrically connected by overlapping a plurality of thin plate-like leads 105-1, 2,... N and joining the end portions 105a and 105b respectively. As the bonding method, for example, ultrasonic bonding can be used.

FIGS. 12, 13, 14 and 15 show assembly drawings when a plurality of cylindrical secondary batteries are connected in series.
The positive electrode terminal 101a of the cylindrical secondary battery 101 and the serial bus bar 104 join the convex portion of the sheet metal portion 104b by, for example, TIG welding (FIG. 12).

  Next, the negative electrode terminal 201c of the other cylindrical secondary battery 201 and the end portion 104d of the flexible portion 104a of the series bus bar 104 are joined by, for example, resistance welding (FIGS. 14 and 15). The sheet metal part is connected to the positive terminal of the cylindrical secondary battery, and the flexible part is connected to the sheet metal part and the negative terminal of the other cylindrical secondary battery adjacent to the cylindrical secondary battery. Matching cylindrical secondary batteries are connected to each other.

The positive terminal of the cylindrical secondary battery 101 and the bus bar 104 are 104b of the bus bar 104.
The negative electrode terminal 101d of the other adjacent cylindrical secondary battery 101 and the bus bar 104 are connected by a sheet metal part, and are connected via a flexible part 104a of the bus bar. The cylindrical secondary battery 101 is covered with an insulating tube 101b made of resin. However, since the cylindrical secondary battery 101 is joined to the flexible portion 104a of the serial bus bar 104, the negative electrode terminal 101d of the cylindrical secondary battery 101 is exposed. ing. The same applies to the cylindrical secondary battery 201.

FIG. 16A is an assembly diagram when a plurality of cylindrical secondary batteries connected in series are connected in parallel, and FIG. 16B is a perspective view after assembly.
A bus bar 105 is connected to the negative electrode terminal exposed on the side surface of the cylindrical secondary battery 301 from the side surface side of the cylindrical secondary battery 301. As a connection method, for example, resistance welding can be used.
The bus bar 105 connecting the negative electrodes of the cylindrical secondary battery 301, the bus bar 104 connecting the positive electrode and the negative electrode of the cylindrical secondary battery 301 by using flexible thin plate-like leads, When stress due to unexpected vibration or impact occurs in 105, the stress generated by the deformation of the flexible portions 104a and 105 is absorbed, and the stress on the joint is suppressed, improving the reliability of the module 100. can do.

  Moreover, although an example of the material of the various members described in the present embodiment is given, the present invention is not limited to this, and other resins and metals may be used. In this embodiment, TIG welding, resistance welding, ultrasonic bonding, etc. are used for welding the bus bar, the cylindrical battery, and the assembly of the bus bar. However, the present invention is not limited to this, and other metallurgical bonding methods are used. For example, laser welding, electron beam welding, resistance welding, pressure welding, arc welding, fusion welding, or the like may be used. In this embodiment, welding is used for joining the bus bar, the cylindrical battery, and the assembly of the bus bar. However, the present invention is not limited to this, and mechanical joining methods such as screw joining and caulking joining are used. May be. In this embodiment, a plurality of leads are used for the bus bar. However, the present invention is not limited to this. For example, one lead may be used. In this embodiment, the number of convex portions of the sheet metal portion 104b of the bus bar 104 is two. However, the number is not limited to this, and may be three or more.

(Example 2)
FIG. 17 is a perspective view of the bus bar according to the second embodiment.
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 already described. Description is omitted about the structure which attached | subjected the same code | symbol shown by and which has the same function.

The bus bar 204 is fixed and electrically connected by, for example, ultrasonic bonding between the end portion 204c of the flexible portion 204a and the terminal portion 204b-3 of the sheet metal portion 204b. The sheet metal portion 204b is provided with one convex portion 204b-1 for joining with the positive electrode terminal of the cylindrical secondary battery. When a stress due to unexpected vibration or impact is generated in the bus bars 204 and 205 by using a flexible thin plate-like lead, the stress generated by the deformation of the flexible portion 204a and the bus bar 205 is reduced. It can absorb, suppress the stress to a joint part, and can improve the reliability of the module 200.
Further, by using a plurality of bus bars 204 in one cylindrical secondary battery, not only welding points but also a plurality of current paths can be provided, redundancy is improved, and the reliability of the module 200 is further improved. Can do.

(Example 3)
18 and 19 are perspective views of the bus bar according to the third embodiment. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 already described. Description is omitted about the structure which attached | subjected the same code | symbol shown by and which has the same function.

The serial bus bar is fixed and electrically connected by, for example, ultrasonic bonding the end portion 304c of the flexible portion 304a and the terminal portion 304b-3 of the sheet metal portion 304b. The sheet metal part 304b is provided with two convex parts 304b-1 for joining with the positive electrode terminal of the cylindrical secondary battery.
The flexible portion 304a and the bus bar 305 are in the form of a shunt wire in which a wire material is knitted, and can cope with deformation with six degrees of freedom.
Absorbs stress generated by deformation of flexible part 304a and bus bar 305 when stress due to unexpected vibration or impact is generated on bus bar or 305 by using flexible shunt wire shaped lead In addition, the stress on the joint can be suppressed, and the reliability of the module 300 can be improved.

Example 4
FIG. 20 shows a perspective view of the connection between the bus bar of Example 4 and the cylindrical secondary battery.
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 already described. Description is omitted about the structure which attached | subjected the same code | symbol shown by and which has the same function.

Negative electrode terminals of a plurality of cylindrical secondary batteries 1101, 1201, 1301, and 1401 having a series bus bar connected to negative electrode terminals 701d, 801d, 901d, and 1001d of a plurality of cylindrical secondary batteries 701, 801, 901, and 1001 1101d, 1201d, 1301d, and 1401d are joined to the parallel bus bars 405 and 505 by, for example, resistance welding.
At that time, the end portions 1104d, 1204d, 1d, and 1404d of the flexible portion 404a of the serial bus bar are placed on (connected to) the parallel bus bar 405, and are connected in parallel with the serial bus bar to the negative electrode terminal of the cylindrical secondary battery. Weld the bus bars at the same time. By doing so, the number of steps can be reduced, and the manufacturing cost can be reduced.
When a stress due to unexpected vibration or impact is generated in the bus bars 1104, 1204, 1, 1404, 504, 505 by using a flexible thin plate-like lead, the flexible portions 1104a, 1204a, 1a 1404a, 405, and 505 are absorbed, the stress which generate | occur | produced can be absorbed, the stress to a junction part can be suppressed, and the reliability of the module 400 can be improved.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

100 Module 101 Cylindrical Secondary Battery 101a Positive Terminal 101b Insulating Tube 101c Joint 101d Negative Terminal 102 Case 103 Case Fixing Screw 104 Bus Bar (Bus Bar for Series)
104a Flexible part 104a-1 Lead 104a-2 Lead 104a-3 Lead 104a-N Lead 104b Sheet metal part 104b-1 Convex part 104b-2 Elongate hole 104b-3 Terminal part 104c End part 104d End part 105 Bus bar (Bus bar for parallel use) )
106 Horn 107 Anvil 200 Module 201 Cylindrical secondary battery 201d Negative electrode terminal 204 Bus bar 204a Flexible portion 204b Sheet metal portion 204b-1 Convex portion 204b-3 Terminal portion 205 Bus bar 300 Module 301d Negative electrode terminal 304 Bus bar 304a
304b-1 Convex part 304b-2 Slot 304b-3 Terminal part 304c End part 304d End part 305 Bus bar 400 Module 401 Cylindrical secondary battery 401d Negative terminal 405 Bus bar 501 Cylindrical secondary battery 501d Negative terminal 504 Bus bar 505 Bus bar 601 Cylindrical secondary battery 601d Negative electrode terminal 701 Cylindrical secondary battery 701d Negative electrode terminal 801 Cylindrical secondary battery 801d Negative electrode terminal 901 Cylindrical secondary battery 901d Negative electrode terminal 1001 Cylindrical secondary battery 1001d Negative electrode terminal 1101 Cylindrical secondary battery 1101d Negative electrode terminal 1104a Flexible portion 1104d End portion 1201 Cylindrical secondary battery 1201d Negative electrode terminal 1204d End portion 1301 Cylindrical secondary battery 1301d Negative electrode terminal 1304d End portion 1401 Cylindrical secondary battery 1401d Negative electrode terminal 1404d End portion

Claims (9)

In an assembled battery having a plurality of cylindrical secondary batteries and a connecting member for connecting the plurality of cylindrical secondary batteries,
The connecting member is a battery pack having flexibility. The assembled battery according to claim 1,
The plurality of cylindrical secondary batteries are connected in the axial direction of the cylindrical secondary battery,
The cylindrical secondary battery has a positive electrode terminal provided on one axial side of the cylindrical secondary battery and a negative electrode terminal provided on the other axial side of the cylindrical secondary battery,
The plurality of cylindrical secondary batteries are assembled batteries in which positive and negative terminals of adjacent cylindrical secondary batteries are connected to each other via a series bus bar as the connection member. The assembled battery according to claim 2,
The bus bar for series is a sheet metal part located between the positive terminal and the negative terminal,
And a flexible part protruding from the sheet metal part, and the flexible part is a battery pack having flexibility. The assembled battery according to claim 3,
The sheet metal part is connected to the positive terminal of the cylindrical secondary battery,
The flexible part is an assembled battery that connects the sheet metal part and the negative electrode terminal of another cylindrical secondary battery adjacent to the cylindrical secondary battery. The assembled battery according to claim 4,
The flexible part is an assembled battery having a curved part curved in the axial direction of the cylindrical secondary battery. In claim 5,
The flexible part is an assembled battery in which a plurality of plate-like leads are stacked. The assembled battery according to claim 1,
The plurality of cylindrical secondary batteries are connected in a direction orthogonal to the axial direction of the cylindrical secondary battery,
The cylindrical secondary battery has a positive electrode terminal provided on one axial side of the cylindrical secondary battery and a negative electrode terminal provided on the other axial side of the cylindrical secondary battery,
The plurality of cylindrical secondary batteries are assembled batteries in which negative electrode terminals of adjacent cylindrical secondary batteries are connected to each other as a connecting member via a parallel bus bar. The assembled battery according to claim 7,
The parallel bus bar is an assembled battery in which a plurality of plate-like leads are stacked. The assembled battery according to claim 6 or 8,
The connection member is an assembled battery which is a shunt wire member in which a wire is knitted.

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