JP2018190591A - Terminal fixing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal fixing structure in which melting of a bottom surface of an insulator hardly occurs when welding a case body of a battery and a sealing lid. SOLUTION: The terminal fixing structure disclosed herein is a battery case sealing lid having a through hole, and a current collecting terminal having a projecting portion that is inserted into the through hole and projects from the sealing lid in an insertion direction. An insulator arranged around the through hole while being in contact with the sealing lid, and an external terminal arranged on the insulator. In the terminal fixing structure, the protruding portion of the current collecting terminal is provided with a caulking portion, and the insulator and the external terminal are sandwiched and fixed between the caulking portion and the sealing lid. A contact area reduction portion is provided on at least one of the sealing lid and the insulator on a surface where the sealing lid and the insulator are in contact with each other. [Selection diagram] Fig. 3

Description

  The present invention relates to a terminal fixing structure. Specifically, the present invention relates to a terminal fixing structure for a battery such as a lithium ion secondary battery.

  2. Description of the Related Art In recent years, secondary batteries such as lithium ion secondary batteries have been used for portable power sources such as personal computers and portable terminals, and power sources for driving vehicles such as electric vehicles (EV), hybrid vehicles (HV), plug-in hybrid vehicles (PHV) Is preferably used.

A general secondary battery has a configuration in which an electrode body and a non-aqueous electrolyte are accommodated in a battery case. In a typical example of such a configuration, the battery case includes a case body having an opening and a sealing lid that closes the opening. A current collecting terminal is attached to the electrode body, and the current collecting terminal is electrically connected to an external terminal outside the battery case.
Specifically, the structure of the current collector terminal portion of the secondary battery has a through hole in the sealing lid of the battery case, and a part of the current collector terminal passes through the through hole to the outside of the battery case. It protrudes. And it has the structure where the upper end part of the current collection terminal was crimped, interposing an external terminal and an insulator between the sealing lids, and the terminals and the sealing lid were fixed.

  The case body and the sealing lid are joined by laser welding or the like as described in Patent Document 1. However, the sealing lid has a glossy surface and a high reflectance of the laser beam. Also, since the sealing lid has a large thermal mass, the sealing lid is less likely to melt than the case body during laser welding. Therefore, Patent Document 1 describes that a groove (unevenness) having a depth of 0.1 mm or less is provided in the portion of the sealing lid irradiated with the laser so that the reflectance of the laser beam for welding is low. Has been.

JP 2002-292486 A

  When laser welding the battery case main body and the sealing lid, the temperature of the welded portion becomes high. As described in Patent Document 1, when the reflectance of the laser light of the sealing lid is lowered, the temperature of the sealing lid tends to be high. Therefore, when laser welding is performed in the vicinity of the portion where the terminals are fixed via the insulator, the distance between the welded portion and the insulator is close, the cross-sectional area of the sealing lid is small, and heat dissipation is low. The welding heat can propagate through the sealing lid and reach the bottom surface of the insulator. For this reason, when the welding heat quantity which propagated is large, the bottom face of an insulator may melt. In this case, melting of the bottom surface of the insulator may cause problems such as a decrease in terminal position accuracy, a decrease in caulking strength, a decrease in sealing performance, and a decrease in insulation. In addition, it is difficult to confirm whether or not the bottom surface of the insulator is melted only by appearance inspection.

  Accordingly, an object of the present invention is to provide a terminal fixing structure in which the bottom surface of an insulator is unlikely to melt when the battery case body and the sealing lid are welded.

  The terminal fixing structure disclosed herein includes a battery case sealing lid having a through-hole, a current collecting terminal inserted into the through-hole and protruding from the sealing lid in the insertion direction, and the sealing lid And an insulator disposed around the through hole while being in contact with the external hole, and an external terminal disposed on the insulator. In the terminal fixing structure, a caulking portion is provided at a protruding portion of the current collecting terminal, and the insulator and the external terminal are sandwiched and fixed between the caulking portion and the sealing lid. A contact area reducing portion is provided on at least one of the sealing lid and the insulator on a surface where the sealing lid and the insulator are in contact with each other.

  According to such a configuration, when the contact area reducing portion is provided, the amount of welding heat transmitted to the bottom surface of the insulator can be reduced when the sealing lid and the case main body are laser welded. Therefore, according to such a structure, when welding the battery case main body and the sealing lid, a terminal fixing structure in which melting of the bottom surface of the insulator hardly occurs is provided.

1 is a schematic perspective view of a lithium ion secondary battery including a terminal fixing structure according to an embodiment of the present invention. It is a cross-sectional schematic diagram along the II-II cross section of FIG. It is the cross-sectional schematic diagram which expanded a part (inside the frame of FIG. 2) of the terminal fixing structure which concerns on one Embodiment of this invention. It is the perspective view which looked at some sealing lids contained in the terminal fixing structure which concerns on one Embodiment of this invention from the battery case outer side. It is the cross-sectional schematic diagram which expanded a part of terminal fixing structure which concerns on embodiment of the modification of this invention.

  Embodiments according to the present invention will be described below with reference to the drawings. It should be noted that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention (for example, a general configuration and manufacturing process of a terminal fixing structure that does not characterize the present invention) It can be grasped as a design matter of a person skilled in the art based on the prior art in the field. The present invention can be carried out based on the contents disclosed in this specification and common technical knowledge in the field. Moreover, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show | plays the same effect | action. In addition, the dimensional relationships (length, width, thickness, etc.) in each drawing do not reflect actual dimensional relationships.

  Hereinafter, as an embodiment of a battery including a terminal fixing structure disclosed herein, a lithium ion secondary battery will be described as an example. However, it is intended that the application target of the present invention be limited to that used for such a battery. It is not a thing. In this specification, the “battery” is a term indicating a general power storage device that can take out electric energy, and includes a primary battery, a secondary battery, and the like. “Secondary battery” means lithium ion secondary battery, metallic lithium secondary battery, sodium secondary battery, nickel metal hydride battery, so-called storage battery (so-called chemical battery) such as nickel cadmium battery, electric double layer capacitor, etc. It is a concept including a capacitor (so-called physical battery).

  FIG. 1 is a schematic perspective view of a lithium ion secondary battery including a terminal fixing structure according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view taken along the line II-II in FIG.

  As shown in FIG. 1, the lithium ion secondary battery 200 has a configuration in which an electrode body 120 and a non-aqueous electrolyte (not shown) are accommodated in a battery case 110. The battery case 110 includes a case main body 112 having an opening and a sealing lid 10 that closes the opening. The battery case 110 may be made of metal or resin, and here is made of aluminum. The sealing lid 10 is provided with a thin safety valve 130 set so as to release the internal pressure when the internal pressure of the battery case 110 rises above a predetermined level. Further, the sealing lid 10 is provided with a liquid injection port 140 for injecting a non-aqueous electrolyte.

  Although not shown, the electrode body 120 has a structure in which a positive electrode and a negative electrode are stacked with a separator interposed therebetween. The electrode body 120 may be either a wound electrode body or a stacked electrode body. The positive electrode of the electrode body 120 is electrically connected to the positive electrode terminal 150 through the positive electrode current collector terminal 20 and the positive electrode external terminal 40. On the positive electrode side, the terminal fixing structure 100 according to the present embodiment is employed. The negative electrode of the electrode body 120 has the same structure as the positive electrode side and is electrically connected to the negative electrode terminal 160.

The terminal fixing structure 100 according to the present embodiment includes a sealing lid 10 having a through hole 12 as shown in FIGS. 1 and 2. Here, the sealing lid 10 has a rectangular flat plate shape having a long side.
The terminal fixing structure 100 according to this embodiment includes a positive electrode current collecting terminal 20. A part of the positive electrode current collecting terminal 20 is inserted into the through hole 12. Further, the positive electrode current collecting terminal 20 has a protruding portion 22 that protrudes from the sealing lid 10 in the insertion direction.
The terminal fixing structure 100 according to this embodiment includes an insulator 30 disposed on the sealing lid 10. The insulator 30 is typically made of an insulating resin material. The insulator 30 includes a through hole 32, and the positive electrode current collector terminal 20 is inserted into the through hole 32. In this way, the insulator 30 is disposed around the through hole 12 while being in contact with the sealing lid 10.
The terminal fixing structure 100 according to the present embodiment includes a positive external terminal 40 disposed on the insulator 30. The positive external terminal 40 is a terminal used outside the battery case 110 and may also be called a positive Z terminal. The positive external terminal 40 includes a through hole 42, and the positive current collecting terminal 20 is inserted into the through hole 42.

  The sealing lid 10 has an outer peripheral groove 14 as shown in FIG. The outer peripheral groove 14 has a function of reducing the heat dissipation of the sealing lid 10 and facilitating melting of the end portion of the sealing lid 10 when the sealing lid 10 and the case body 112 are welded. Further, the outer circumferential groove 14 has a function of suppressing the welding bead from flowing in the inner direction of the sealing lid 10.

  The protruding portion 22 of the positive electrode current collecting terminal 20 is provided with a caulking portion 22a. Between the caulking portion 22a and the sealing lid 10, the insulator 30 and the positive electrode external terminal 40 are sandwiched and fixed. The sealing lid 10 and the positive external terminal 40 are insulated by the insulator 30.

  A gasket 50 is disposed on the inner side of the battery case 110 of the sealing lid 10. The gasket 50 is typically made of an insulating resin material. The sealing lid 10 and the positive electrode current collecting terminal 20 are insulated by the gasket 50.

FIG. 3 shows an enlarged cross-sectional view of a part of the terminal fixing structure 100 according to the present embodiment (inside the frame of FIG. 2). FIG. 4 is a perspective view of a part of the sealing lid 10 from the outside of the battery case 110.
As illustrated, three non-contact grooves 16 are provided on the surface of the sealing lid 10 that contacts the insulator 30. The non-contact groove 16 is provided along a direction perpendicular to the longitudinal direction of the sealing lid 10 (width direction of the sealing lid 10). As shown in FIG. 3, the sealing lid 10 does not contact the insulator 30 in the portion where the non-contact groove 16 is formed on the contact surface of the sealing lid 10 with the insulator 30. That is, the contact area reducing portion is provided by the non-contact groove 16.
The contact area reducing portion (non-contact groove) 16 is formed in a portion where the distance between the end portion of the sealing lid 10 to be laser welded and the insulator 30 is short on the surface of the sealing lid 10 that contacts the insulator 30. .
By providing the contact area reducing portion (non-contact groove) 16 in this manner, the amount of welding heat transmitted to the bottom surface of the insulator 30 can be reduced when the sealing lid 10 and the case main body 112 are laser-welded. . Therefore, melting of the bottom surface of the insulator 30 can be suppressed, and thereby occurrence of problems such as a decrease in terminal position accuracy, a decrease in caulking strength, a decrease in sealing performance, and a decrease in insulation can be suppressed.

  Moreover, the non-contact groove | channel 16 is extended to the exterior of the surface where the sealing cover 10 contacts the insulator 30, as shown in FIG. According to such a non-contact groove 16, at the time of welding when manufacturing the lithium ion secondary battery 200, the cooling gas is poured from the non-contact groove 16 to cool the surface where the sealing lid 10 and the insulator 30 are in contact with each other. The melting of the bottom surface of the insulator 30 can be further suppressed. In addition, when the bottom surface of the insulator 30 is melted, the melted insulator 30 flows out from the surface where the sealing lid 10 and the insulator 30 are in contact through the non-contact groove 16, so that melting of the bottom surface of the insulator 30 occurs. Presence / absence can be confirmed by visual inspection.

The shape, length, width, depth, number, etc. of the non-contact grooves 16 can be appropriately set according to the size of the lithium ion secondary battery 200 from the viewpoint of reducing the amount of welding heat transmitted to the bottom surface of the insulator 30. Good.
For example, the depth of the non-contact groove 16 is, for example, 0.1 mm or more, preferably 0 from the viewpoint of effectively reducing the amount of welding heat to be conducted without reliably contacting the insulator 30 and the sealing lid 10. .15 mm or more. In addition, from the viewpoint of suppressing deformation during caulking due to a decrease in strength of the sealing lid 10 due to the non-contact groove 16 and a change in penetration depth during laser welding, the depth of the non-contact groove 16 is, for example, 0.4 mm. Or less, preferably 0.3 mm or less.
The number of non-contact grooves 16 is not particularly limited, and may be two, for example.
The cross-sectional shape of the non-contact groove 16 is not particularly limited, and may be, for example, a quadrangle, a triangle, a trapezoid, or the like.
The non-contact groove 16 is preferably a region between the through hole 12 and the end of the sealing lid 10 and is covered with the insulator 30, and the contact area between the sealing lid 10 and the insulator 30 is such that the sealing lid 10 Is provided to be 40% or less with respect to the area covered by the insulator 30.

As described above, the embodiment in which the contact area reducing unit is provided in the sealing lid on the surface where the sealing lid and the insulator are in contact has been described. However, the contact area reducing unit is provided in at least one of the sealing lid and the insulator. Just do it.
Therefore, as a modified example, an embodiment in which the contact area reducing unit is provided in the insulator will be described with reference to FIG.

In the modification shown in FIG. 5, only the insulator and the sealing lid are different from the above-described embodiment, and thus the description of other members is omitted.
In this modification, the sealing lid 10A does not have the non-contact groove 16 unlike the sealing lid 10 shown in FIGS. On the other hand, the insulator 30 </ b> A has a plurality of non-contact grooves 36.
The non-contact groove 36 is provided along the longitudinal direction of the sealing lid 10A. In the portion where the non-contact groove 36 is formed on the surface where the sealing lid 10A and the insulator 30A are in contact, the sealing lid 10A does not contact the insulator 30A as shown in FIG. That is, the contact area reducing portion is provided by the non-contact groove 36.
The contact area reducing portion (non-contact groove) 36 is formed in a portion where the distance between the end portion on the sealing lid 10A to be laser welded and the insulator 30A is close to the contact surface of the sealing lid 10A with the insulator 30A. .

  By providing the contact area reducing portion (non-contact groove) 36 as described above, the amount of welding heat transmitted to the bottom surface of the insulator 30A can be reduced when the sealing lid 10A and the case main body 112 are laser-welded. . Therefore, it is possible to suppress melting of the bottom surface of the insulator 30A, and thereby it is possible to suppress occurrence of problems such as a decrease in terminal position accuracy, a decrease in caulking strength, a decrease in sealing performance, and a decrease in insulation.

  The shape, length, width, depth, number, etc. of the non-contact grooves 36 may be set as appropriate from the viewpoint of making it difficult for welding heat to be conducted to the bottom surface of the insulator 30A.

  As described above, the embodiment in which the contact area reduction unit is provided in the insulator has been described as a modification. However, the embodiment in which the contact area reduction unit is provided in the sealing lid described above, and the contact area reduction unit is provided in the insulator. It is also possible to combine the embodiment described above and to provide an embodiment in which the contact area reducing portion is provided on both the sealing lid and the insulator.

  In the above description, the contact area reduction unit is configured by a non-contact groove, but the contact area reduction unit is not limited to the non-contact groove. The contact area reducing part may be a part where the contact area is reduced more than the area of the region where the sealing lid and the insulator face each other, and a convex part shape that reduces the contact area or a concave part shape other than the groove It may be configured. For example, the contact area reducing portion may be configured by a convex portion such as a square protrusion, a cylindrical protrusion, a spherical protrusion, or a concave portion such as a bottomed hole.

  In the above embodiment, only the positive electrode side has been described, but the terminal fixing structure disclosed herein can also be adopted on the negative electrode side.

  In the battery including the terminal fixing structure disclosed herein, since melting of the bottom surface of the insulator is suppressed during welding, the distance between the terminal fixing structure including the insulator and the welded portion (end portion of the sealing lid) is smaller than before. can do. Therefore, the penetration quality of welding can be stabilized at the time of welding when manufacturing a battery. Also, the thickness of the battery can be made thinner than before.

  As mentioned above, although the specific example of this invention was demonstrated in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

10, 10A Sealing lid 12 Through hole 14 Peripheral groove 16 Non-contact groove 20 Positive current collecting terminal 22 Protruding portion 22a Caulking portion 30, 30A Insulator 36 Non-contact groove 40 Positive external terminal 50 Gasket 100 Terminal fixing structure 110 Battery case 112 Case body 120 Electrode body 130 Safety valve 140 Injection port 150 Positive electrode terminal 160 Negative electrode terminal 200 Lithium ion secondary battery

Claims (1)

A battery case sealing lid having a through hole;
A current collecting terminal inserted into the through hole and having a protruding portion protruding in the insertion direction from the sealing lid;
An insulator disposed around the through hole while in contact with the sealing lid;
An external terminal disposed on the insulator;
With
A terminal fixing structure in which a caulking portion is provided in a protruding portion of the current collecting terminal, and the insulator and the external terminal are sandwiched and fixed between the caulking portion and the sealing lid,
On the surface where the sealing lid and the insulator are in contact, at least one of the sealing lid and the insulator is provided with a contact area reducing unit,
Terminal fixing structure characterized by this.

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