JP2013051185A - Battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in bond strength in a structure where an external terminal of a battery is welded with an electric connection member.SOLUTION: A battery pack includes: a plurality of batteries 30 having external terminals including a negative electrode terminal 50 and a positive electrode terminal; a bus bar 40 for connecting external terminals of adjacent two batteries 30 each other; a connecting member 70 welded to the external terminals and the bus bar 40 and electrically connecting the external terminals with the bus bar 40; a welded part 80 where the external terminals and the connecting member 70 are welded; and a welded part 82 where the bus bar 40 and the connecting member 70 are welded. The welded part 80 has a shape recessed to the outermost surface of the connecting member 70, and an apical surface 50d of the negative electrode terminal 50 is connected to a connected surface 81 of the welded part 80 without a level difference.

Description

  The present invention relates to an assembled battery.

  Generally, in an assembled battery in which a plurality of batteries are connected, one positive terminal and the other negative terminal of adjacent batteries are connected in series with a bus bar as a terminal connecting member. As a connection structure between the external terminal including the positive terminal and the negative terminal and the bus bar, the external terminal is inserted into the opening provided in the bus bar, and a fixing screw is screwed to the tip of the external terminal to thereby connect the external terminal and the bus bar. Is known (see Patent Document 1).

JP 2004253331 A

  When the external terminal and the bus bar are screwed and fixed as in the conventional structure described above, the fixing screw may be loosened. For this reason, there is room for improvement in improving the connection reliability between the external terminal and the bus bar. On the other hand, the structure which connects an external terminal and a bus bar via a connection member by welding a part of external terminal and a connection member, and welding the other part of a bus bar and a connection member can be considered.

  As a result of intensive studies on a configuration in which the external terminal and the bus bar are connected by welding via a connecting member, the present inventors have found the following problems. That is, when the distal end portion of the external terminal and the connecting member or the like are welded, when a load is applied to the connecting member or the like, the stress accompanying the load is concentrated on the welded portion. As a result, the welded portion may be damaged, and the connection strength between the external terminal and the connecting member may be reduced.

  This invention is made | formed in view of such a subject, The objective is to provide the technique which suppresses the fall of joint strength in the structure which welded the external terminal and electric connection member (bus bar) of the battery. .

  One embodiment of the present invention is an assembled battery. The assembled battery includes a plurality of batteries each having an electrode body, a housing that houses the electrode body, and an external terminal that is provided outside the housing and is electrically connected to the electrode body, and the external terminal An electrical connection member for electrically connecting external terminals of two adjacent batteries, and a terminal connection portion which is a tip region of the external terminal inserted through the through hole And a conductive connecting member that fixes the electric connecting member around the terminal connecting portion, and a welded portion that connects the terminal connecting portion and the connecting member, and the outermost surface of the connecting member is A plane that is substantially orthogonal to the axis of the terminal connection portion extending in the protruding direction, and the welded portion has a shape recessed toward the bottom surface of the housing from the plane, and the axis of the terminal connection portion The upper surface of the welded portion has a downwardly curved shape There, the distal end surface of the terminal connecting portion and wherein the connecting without end upper surface and the step of the side of the terminal connecting portion of the weld.

  According to the assembled battery of the above aspect, when a load is applied to the connecting member, it is possible to suppress the stress accompanying the load from concentrating on the welded portion, and thus connection reliability between the terminal connecting portion and the connecting member. Can be improved.

  According to the present invention, there is provided a technique for suppressing a decrease in joint strength in a structure in which an external terminal of a battery and an electrical connection member are welded.

It is a perspective view which shows schematic structure of the assembled battery which concerns on embodiment. It is sectional drawing which shows schematic structure of a battery. It is an expansion perspective view which shows schematic structure of the connection part of the external terminal of a battery, and a bus-bar. It is sectional drawing along the AA line of FIG. FIG. 5A is a perspective view showing a schematic structure of the connecting member. FIG. 5B is a cross-sectional view taken along line BB in FIG. 6A to 6C are process cross-sectional views illustrating the battery connection method according to the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.
(Embodiment)

  FIG. 1 is a perspective view showing a schematic structure of the assembled battery according to the embodiment. As shown in FIG. 1, the assembled battery 10 includes a plurality of batteries 30 and a bus bar 40 (electrical connection member) that connects these batteries 30. In the present embodiment, a total of five batteries 30 are connected in series to form the assembled battery 10. Note that the number of the batteries 30 is not particularly limited. Moreover, although all the five batteries 30 are connected in series, some may be connected in parallel.

  The batteries 30 each have a flat rectangular parallelepiped casing, and are arranged in parallel at predetermined intervals so that the main surfaces thereof are opposed and substantially parallel. On the upper surface of the casing of the battery 30, a negative electrode terminal 50 is provided near one end in the longitudinal direction, and a positive electrode terminal 60 is provided near the other end. Hereinafter, the negative electrode terminal 50 and the positive electrode terminal 60 are collectively referred to as external terminals as appropriate. The negative electrode terminal 50 and the positive electrode terminal 60 of the adjacent battery 30 are arranged so as to be opposite to each other. One positive terminal 60 and the other negative terminal 50 of two adjacent batteries 30 are electrically connected by a bus bar 40, and five batteries 30 are connected in series.

  The battery 30 is accommodated in a housing (not shown). The positive terminal 60 ′ serving as one terminal of the series connection of the batteries 30 and the negative terminal 50 ′ serving as the other terminal can be connected to an external load (both not shown) via wiring routed outside the housing. It has become.

  FIG. 2 is a cross-sectional view showing a schematic structure of the battery. As shown in FIG. 2, the battery 30 includes an outer can (housing) 31 in which an electrode body 32 in which positive and negative electrodes are wound in a spiral shape is housed laterally with respect to the can axis direction of the outer can 31. Yes. The opening of the outer can 31 is sealed by a sealing plate 33 that constitutes a part of the housing. The sealing plate 33 is provided with a negative electrode terminal 50 and a positive electrode terminal 60. The sealing plate 33 is formed with a gas discharge valve (not shown).

  The negative electrode terminal 50 has a base portion 50a and a terminal connection portion 50b protruding from the base portion 50a. The terminal connection portion 50b refers to a tip region of the negative electrode terminal 50 that is inserted into a through hole 41 of a bus bar 40 described later. In the present embodiment, the terminal connection portion 50b is provided with a recess 52 in which the tip side of the terminal connection portion 50b is an opening. The front end surface 50d of the terminal connection portion 50b is the end surface of the negative electrode terminal 50 that is farthest from the outer can 31 (housing), and is away from the outer can 31, in other words, the protrusion of the terminal connection portion 50b. It has at least a part of a plane substantially orthogonal to the direction.

  The base portion 50a is substantially cylindrical and has a flange portion 50c on the outer peripheral surface. The base portion 50 a of the negative electrode terminal 50 is fitted into the negative electrode opening 33 a of the sealing plate 33 with the gasket 34 in contact with the side surface. The gasket 34 is also in contact with the surface of the flange 50c that faces the sealing plate 33. Further, the base portion 50 a is connected to the negative electrode tab member 54 on the battery inner side of the sealing plate 33.

  A substantially cylindrical terminal connection portion 50b is provided integrally with the base portion 50a so as to protrude upward at the tip of the base portion 50a located outside the battery. A recess 51 is provided at the tip of the base 50a located inside the battery so that a side wall is formed along the negative electrode opening 33a. The negative electrode terminal 50 is fixed to the negative electrode tab member 54 by caulking so that the edge portion of the recess 51 widens.

  Further, the negative electrode terminal 50 is formed with a through hole 53 that communicates with the recess 51 and the recess 52. The diameter of the through hole 53 is smaller than the diameters of the recess 51 and the recess 52. A resin plug 200a formed of a resin such as a polyester-based thermoplastic elastomer or a silicone resin is filled in a part of the through hole 53 on the recess 52 side and the interior of the recess 52 continuous thereto. The resin plug 200a is provided so as to at least close the through hole 53, and the space inside the battery inside the resin plug 200a is sealed. The metal lid 210a is a flat plate-like member and is bonded on the resin stopper 200a. The metal lid 210a is formed, for example, by punching with a mold. The metal lid 210a suppresses moisture from entering the gap between the resin plug 200a and the negative electrode terminal 50, and consequently suppresses corrosion of the negative electrode terminal 50 by moisture. Although the fixing method of the metal lid 210a is not particularly limited, the metal lid 210a may be bonded to the resin plug 200a by the adhesive force of the resin plug 200a itself, or may be bonded to the resin plug 200a using an adhesive.

  An insulating plate 35 is provided between the negative electrode tab member 54 and the battery inner surface of the sealing plate 33. The insulating plate 35 and the gasket 34 are in contact with each other at the negative electrode opening 33a. Thereby, the negative electrode tab member 54 and the negative electrode terminal 50 are insulated from the sealing plate 33. The negative electrode tab member 54 is connected to the negative electrode current collector plate group 32 a protruding from one end surface of the electrode body 32. The negative electrode current collector plate group 32 a is a bundle of a plurality of negative electrode current collector plates protruding from one end face of the electrode body 32.

  The positive electrode terminal 60 includes a base portion 60a and a terminal connection portion 60b protruding from the base portion 60a. The terminal connection portion 60b refers to a tip region of the positive electrode terminal 60 that is disposed or inserted in a through hole 41 of the bus bar 40 described later. In the present embodiment, the terminal connection portion 60b is provided with a recess such that the distal end side of the terminal connection portion 60b is an opening, and the terminal connection portion 60b has a partially hollow cylindrical shape. In the present embodiment, the terminal connection portion 60b is provided with a recess 62 in which the tip end side of the terminal connection portion 60b is an opening. The front end surface 60d of the terminal connection portion 60b is an end surface that is located farthest from the outer can 31 (housing) in the positive electrode terminal 60, and at least a plane that is substantially orthogonal to the direction away from the outer can 31 is at least partially. Have.

  The base 60a is substantially cylindrical and has a flange 60c on the outer peripheral surface. The base portion 60 a of the positive electrode terminal 60 is fitted into the positive electrode opening 33 b of the sealing plate 33 with the gasket 34 in contact with the side surface. The gasket 34 is also in contact with the surface of the flange 60c that faces the sealing plate 33. The base portion 60 a is connected to the positive electrode tab member 64 on the battery inner side of the sealing plate 33.

  A substantially cylindrical terminal connection portion 60b is provided integrally with the base portion 60a so as to protrude upward at the tip of the base portion 60a located outside the battery. A recess 61 is formed at the tip of the base 60a located inside the battery so that a side wall is formed along the positive electrode opening 33b. The positive electrode terminal 60 is fixed to the positive electrode tab member 64 by caulking the edge portion of the recess 61 so as to expand.

  The positive electrode terminal 60 has a through hole 63 communicating with the recess 61 and the recess 62. The diameter of the through hole 63 is smaller than the diameter of the recess 61 and the recess 62. A resin plug 200b formed of a resin such as a polyester-based thermoplastic elastomer or a silicone resin is filled in a part of the through hole 63 on the recess 62 side and the interior of the recess 62 continuous therewith. The resin plug 200b is provided so as to block at least the through hole 63, and the space inside the battery inside the resin plug 200b is sealed. The metal lid 210b is a flat plate-like member and is bonded onto the resin stopper 200b. The metal lid 210b is formed, for example, by punching with a mold. The metal lid 210b suppresses moisture from entering the gap between the resin plug 200b and the positive electrode terminal 60, and consequently suppresses corrosion of the positive electrode terminal 60 by moisture. Although the fixing method of the metal lid 210b is not particularly limited, the metal lid 210b may be bonded to the resin plug 200b by the adhesive force of the resin plug 200b itself, or may be bonded to the resin plug 200b using an adhesive.

  An insulating plate 35 is provided between the positive electrode tab member 64 and the battery inner surface of the sealing plate 33. The insulating plate 35 and the gasket 34 are in contact with each other at the positive electrode opening 33b. Thereby, the positive electrode tab member 64 and the positive electrode terminal 60 are insulated from the sealing plate 33. The positive electrode tab member 64 is connected to the positive electrode current collector plate group 32 b protruding from the other end face of the electrode body 32. The positive electrode current collector plate group 32 b is a bundle of a plurality of positive electrode current collector plates protruding from the other end face of the electrode body 32.

  The bus bar 40 is a band-shaped member made of a conductive material such as metal. At both ends of the bus bar 40, through holes 41 (see FIG. 4) are provided. One negative terminal 50 of the adjacent battery 30 is inserted into one through hole 41 of the bus bar 40, and the other positive terminal 60 of the adjacent battery 30 is inserted into the other through hole 41.

  FIG. 3 is an enlarged perspective view showing a schematic structure in the vicinity of the connection portion between the external terminal of the battery and the bus bar. 4 is a cross-sectional view taken along line AA in FIG. FIG. 5A is a perspective view showing a schematic structure of the connecting member. FIG. 5B is a cross-sectional view taken along line BB in FIG. 3 and 4, the negative electrode terminal 50 is illustrated as an example of the external terminal.

  As shown in FIGS. 3 and 4, the negative terminal 50 and the bus bar 40 are connected via a connecting member 70. In other words, a part of the connecting member 70 and the negative electrode terminal 50 are welded at the welded portion 80, and another part of the connecting member 70 and the bus bar 40 are welded at the welded portion 82, whereby the negative electrode terminal 50 and the busbar 40. Are connected to each other.

  As shown in FIGS. 5A and 5B, the connecting member 70 is a ring-shaped member made of a conductive material such as metal, and has a through hole 72 in the center. The thickness of the connecting member 70 is, for example, about 0.1 mm to about 5 mm.

  The terminal connection portion 50 b of the negative electrode terminal 50 is inserted into the through hole 41 of the bus bar 40, and a part of the tip protrudes from the opening of the through hole 41 on the side opposite to the battery 30. The lower surface of the bus bar 40 is in contact with the upper surface of the flange portion 50 c of the negative electrode terminal 50. Further, the terminal connection portion 50 b is disposed in the through hole 72 of the connecting member 70 disposed on the bus bar 40.

  And the inner peripheral part of the connection member 70 and the terminal connection part 50b are connected by the welding part 80. FIG. In the present embodiment, the terminal connection portion 50b has a tip surface 50d that is closer to the bottom surface of the outer can 31 (the bottom surface of the battery 30) than the outermost surface 71 of the connecting member 70 in the portion adjacent to the welded portion 80. However, the front end surface 50 d may be flush with the outermost surface 71 of the connecting member 70. The connection surface 81, which is the surface of the welded portion 80 opposite to the battery 30, smoothly connects the front end surface 50 d and the outermost surface 71 without a step, and the bottom surface of the outer can 31 than the outermost surface 71 of the connection member 70. The shape is recessed on the side. As shown in FIG. 4, in the cross section including the axis of the terminal connection portion 50b, the connecting surface 81 has a downwardly convex curved shape. Further, the back surface 83 of the welded portion 80 on the side opposite to the connecting surface 81 has a shape that approaches the bottom surface of the outer can 31 as it is closer to the terminal connecting portion 50b. As will be described later, the welded portion 80 is formed mainly by melting the inner peripheral portion of the connecting member 70 by laser irradiation. Accordingly, the innermost remaining portion of the connecting member 70 is in contact with the welded portion 80.

  Further, the lower portion of the outer peripheral surface of the base portion 70 a and the bus bar 40 are connected by a welded portion 82.

(Battery connection method)
Next, a battery connection method for electrically connecting the external terminal of the battery 30 and the bus bar 40 will be described with reference to FIGS. 6 (A) to 6 (C). 6A to 6C are process cross-sectional views illustrating the battery connection method according to the embodiment. 6A to 6C illustrate a negative electrode terminal 50 as an example of the external terminal.

  First, as shown in FIG. 6A, a battery 30 including an external terminal having a base portion 50a and a terminal connection portion 50b protruding from the base portion 50a is prepared. Also, a metal flat ring-shaped connecting member 70 in which the through hole 72 is formed is prepared. Also, a bus bar 40 having a through hole 41 formed at a predetermined position is prepared. Then, the negative electrode terminal 50 and the through hole 41 of the bus bar 40 are aligned, the bus bar 40 is placed on the negative electrode terminal 50, and the terminal connection portion 50 b is inserted into the through hole 41. Subsequently, the negative electrode terminal 50 and the through hole 72 of the connecting member 70 are aligned, the connecting member 70 is placed on the bus bar 40, and the terminal connection portion 50 b is inserted into the through hole 72.

  As shown in FIG. 6B, when the connecting member 70 is placed on the bus bar 40, the outermost surface 71 of the connecting member 70 and the tip surface 50 d of the negative electrode terminal 50 are flush with each other. In this state, the connecting member 70 in the vicinity of the negative electrode terminal 50 is irradiated with the laser L to melt a part of the connecting member 70 and a part of the negative electrode terminal 50, and the connecting member 70 and the negative electrode terminal 50 are welded. The melting rate of the connecting member 70 and the negative electrode terminal 50 when melting a part of the connecting member 70 and a part of the negative electrode terminal 50 is mainly the connecting member 70. As a result of the laser irradiation, a part of the connecting member 70 and a part of the negative electrode terminal 50 are melted, whereby the welded portion 80 having the above-described form is formed. In addition, the laser L is irradiated to the lower part of the outer peripheral surface of the connecting member 70 and the bus bar 40 to melt a part of the connecting member 70 and a part of the upper surface of the bus bar 40, thereby connecting the connecting member 70 and the bus bar 40. Weld. The laser L is emitted over the entire periphery of the portion where the inner peripheral portion of the connecting member 70 and the negative electrode terminal 50 abut and the entire periphery of the portion where the lower portion of the outer peripheral surface of the connecting member 70 and the bus bar 40 are in contact. Note that the irradiation range of the laser L is not limited to this, and may be a part of a portion where the inner peripheral portion of the connecting member 70 and the terminal connection portion 50b abut as long as sufficient strength is obtained.

  As shown in FIG. 6 (C), the welded portion 80 is formed between the remaining portion of the connecting member 70 and the terminal connecting portion 50b by the laser L irradiation, and the connecting member 70 and the terminal connecting portion 50b are connected. Connected. At this time, a part of the terminal connection portion 50 b remains, and is closer to the battery 30 or the casing than the outermost surface 71 of the connecting member 70 in the portion adjacent to the welded portion 80. Further, a welded portion 82 is formed between the remaining portion of the connecting member 70 and the bus bar 40, and the connecting member 70 and the bus bar 40 are connected. Note that either the connection between the connecting member 70 and the bus bar 40 or the connection between the connecting member 70 and the negative electrode terminal 50 may be performed first or in parallel.

  As described above, in the assembled battery 10 according to the present embodiment, in the cross section including the axis of the terminal connection portion 50b, the connecting surface 81 of the welded portion 80 has a downwardly convex curved shape, and the connecting surface 81 and the terminal The front end surface 50d of the connecting portion 50b is connected without a step. According to the assembled battery 10 having such a structure, when a load is applied to the connecting member 70, the stress associated with the load is suppressed from being concentrated on the weld 80. Thereby, since it is reduced that damage is given to the terminal connection part 50b, the fall of the connection strength between the terminal connection part 50b and the connection member 70 can be suppressed.

10 assembled battery, 30 battery, 40 bus bar, 50 negative terminal, 50a base, 50b terminal connection, 50d tip surface, 60 positive terminal, 60a base, 60b terminal connection, 70 connecting member, 71 outermost surface, 80, 82 welding Part

Claims (2)

A plurality of batteries each having an electrode body, a housing that houses the electrode body, and an external terminal that is provided outside the housing and is electrically connected to the electrode body;
An electrical connection member having a through hole through which the external terminal is inserted, and electrically connecting external terminals of two adjacent batteries;
A conductive connecting member that fixes a terminal connecting portion that is a tip region of the external terminal inserted through the through-hole, and the electrical connecting member around the terminal connecting portion;
A welded portion connecting the terminal connecting portion and the connecting member;
With
The outermost surface of the connecting member includes a plane that is substantially orthogonal to an axis that faces the protruding direction of the terminal connection portion,
The welded portion has a shape recessed on the bottom surface side of the housing from the plane,
In the cross section including the axis of the terminal connection portion, the upper surface of the welded portion has a downwardly convex curved shape, and the tip end surface of the terminal connection portion is stepped from the end upper surface of the welded portion on the terminal connection portion side. A battery pack characterized by being connected without any problems.   2. The assembled battery according to claim 1, wherein in the cross section including the axis of the terminal connection portion, the back surface of the welded portion has a shape that approaches the bottom surface of the housing as the distance from the terminal connection portion increases.

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