JP2019121468A - Sealed battery - Google Patents

Abstract

To provide a sealed battery in which a conductive state between a negative inner terminal and a negative outer terminal becomes stably and has an excellent state.SOLUTION: The present invention provides a sealed battery comprising: an electrode body; a battery case; an inner terminal of a positive and negative electrode; and an outer terminal of the positive and negative electrode. The inner terminal in the negative electrode includes: a pedestal part; an axial part provided so as to penetrate a penetration hole or the like of the outer terminal of the negative electrode while being projected from the pedestal part; and a caulked part projected to an outer side from the penetration hole of the outer terminal of the negative electrode, and caulked and formed in a peripheral edge part surrounding the penetration hole of the outer terminal of the negative electrode. The peripheral edge part in a radial direction of the axial part of the caulked part is welded to a plate part. The welding is performed to the caulked part that a distance from a front surface opposite to the side where the plate part of the caulked part is positioned to the plate part is equal to 0.1 mm or more and 0.55 mm or less in the peripheral edge part of the caulked part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sealed battery.

  BACKGROUND ART In recent years, lithium ion batteries, nickel hydrogen batteries and other secondary batteries have increased in importance as vehicle-mounted power supplies or as power supplies for personal computers and portable terminals. In particular, a lithium ion secondary battery which is light in weight and capable of obtaining a high energy density is preferably used as a high power supply for vehicle mounting. In this type of secondary battery, a battery structure is known in which an electrode body is housed inside a battery case, and an electrode terminal connected to the electrode body is drawn out to an upper end (lid) of the battery case. For example, a sealed battery is widely known in which an electrode terminal is drawn out to a lid of a battery case and caulked and fixed to the lid via a gasket. Patent document 1 is disclosed as a prior art regarding this type of sealed battery.

JP, 2016-105355, A

  According to Patent Document 1, the cover and the external terminal are fastened by being caulked and deformed after the caulking member (internal terminal) is inserted into the through hole of the cover and the through hole of the external terminal. A sealed battery is disclosed. According to this type of sealed battery, the contact portion between the crimped portion of the caulking member and the external terminal serves as a conductive path between the two terminals (that is, the caulking member and the external terminal).

  Here, the battery case, the external terminal, and the caulking member (internal terminal) are integrally assembled by caulking in order to lower the conduction resistance (electrical resistance) between the two terminals, and the caulking member is caulked and deformed. There is a case where welding (for example, laser welding) is performed to firmly bond a portion where the portion and the external terminal are in contact with each other. According to such welding, the conduction area between the two terminals (that is, the area of the portion where the conduction path is formed) is increased, whereby low resistance between the two terminals can be realized.

  However, in general, due to the nature of joining of parts by welding, it has been difficult to improve machining accuracy beyond a certain level. For this reason, in order to stably realize low resistance between the caulking member (internal terminal) and the external terminal, it is necessary to increase the conduction area between both terminals by welding as much as possible.

  In particular, such problems tend to be noticeable when welding and joining negative terminals, which often use copper as a material. The present invention has been made in view of such a point, and the conduction state between the caulking member on the negative electrode side (negative electrode internal terminal) and the external terminal on the negative electrode side (negative electrode external terminal) becomes stable and excellent. It is an object of the present invention to provide a sealed battery to be obtained.

  According to the present invention, an electrode body comprising a positive electrode and a negative electrode, a battery case accommodating the electrode body, internal terminals of positive and negative electrodes electrically connected to the positive and negative electrodes inside the case, and the case And an external terminal of positive and negative electrodes respectively provided outside the positive and negative electrodes and electrically connected to the internal terminals of the positive and negative electrodes.

  The negative electrode external terminal has a plate portion formed in the direction along the outer wall of the case. Further, the negative electrode internal terminal is provided with a pedestal portion located inside the case, and a shaft portion projecting from the pedestal portion and penetrating through the through hole of the case and the through hole of the plate portion. The shaft portion is provided at an end opposite to the side where the pedestal portion is located, and is formed by being crimped to a peripheral portion surrounding the through hole of the plate portion by protruding outward from the through hole of the plate portion And a stiffening portion.

The peripheral edge portion in the radial direction of the shaft portion of the caulking portion is welded to the plate portion. Here, the welding, the following conditions: in the peripheral portion of the caulking portion, the side on which the plate portion of the caulking portion is located a distance h _a from the surface opposite to the plate portion, 0. 1 mm or more and 0.55 mm or less;

  According to this structure, the peripheral part in the radial direction of the axial part of the caulking part of the negative electrode internal terminal and the negative electrode external terminal can be suitably welded. Thereby, the conductive area between the negative electrode internal terminal and the negative electrode external terminal can be increased. The increase in the conductive area can contribute to quality stabilization of the conduction state between the two terminals realized by welding the negative electrode internal terminal and the negative electrode external terminal.

It is a figure which shows the principal part cross section of the sealed battery which concerns on one Embodiment. It is an exploded view which shows typically each member before caulking processing concerning one embodiment. It is sectional drawing for demonstrating caulking processing of the negative electrode internal terminal which concerns on one Embodiment. It is a side view which expands and shows a peripheral part and a central part of a caulking part of a negative electrode internal terminal concerning one embodiment. It is sectional drawing for demonstrating the welding process of the negative electrode internal terminal which concerns on one Embodiment, and a negative electrode external terminal. It is a top view for demonstrating the welding process of the negative electrode internal terminal which concerns on one Embodiment, and a negative electrode external terminal. It is sectional drawing by the VII-VII 'line | wire in FIG. It is a graph which shows the relationship between the edge height of a crimping part, and a conduction area.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings as appropriate. Matters necessary for the implementation of the present invention other than the matters specifically mentioned in the present specification can be understood as design matters for a person skilled in the art based on prior art in the art. The present invention can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field. In addition, in the following drawings, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show the same effect | action, and the overlapping description may be abbreviate | omitted or simplified. Also, the dimensional relationships (length, width, thickness, etc.) in the drawings do not necessarily reflect the actual dimensional relationships.

  Although not intended to be particularly limited, in the following, the wound electrode assembly (wound electrode assembly) and the non-aqueous liquid electrolyte (electrolytic solution) are housed in a flat rectangular (box) case. The present invention will be described by taking a sealed lithium ion secondary battery in the form as an example.

  The principal part cross section of the sealed battery 100 which concerns on FIG. 1 at this embodiment is shown. As shown in FIG. 1, the sealed battery 100 includes a negative electrode internal terminal 10, a battery case 20, and a negative electrode external terminal 30. The negative electrode internal terminal 10 is electrically connected to the negative electrode of the electrode body inside the battery case 20. In addition, the negative electrode external terminal 30 is provided on the outside of the battery case 20 and is electrically connected to the negative electrode internal terminal 10. Sealed battery 100 further includes a gasket 40 and an insulator 50. Here, the negative electrode internal terminal 10 in FIG. 1 shows a state after caulking as described later.

<Battery case>
The battery case 20 includes a box-shaped (that is, a bottomed rectangular cylindrical) case main body in which one of the narrow surfaces in the flat rectangular parallelepiped shape is an opening, and a lid that closes the opening. As a material which constitutes battery case 20, the thing similar to what is used by a common lithium ion secondary battery etc. can be used suitably. From the viewpoint of heat dissipation and the like, a battery case 20 in which almost the entire body and lid are made of metal (for example, aluminum, stainless steel (SUS), steel, etc.) can be preferably employed. A negative electrode external terminal 30 electrically connected via the negative electrode of the wound electrode body and the negative electrode internal terminal 10 is disposed on the upper surface (here, the lid) of the battery case 20. Further, the battery case 20 is formed with a through hole 22 through which a shaft portion 12 of the negative electrode internal terminal 10 described later is inserted. In this embodiment, the lithium ion secondary battery 100 is a square battery, but the shape of the battery is not limited to a square, and may be any shape such as a cylindrical shape.

<Negative external terminal>
The negative electrode external terminal 30 is provided on the outside of the battery case 20. In the present embodiment, the negative electrode external terminal 30 has a plate portion 34 formed in a direction along the outer wall of the battery case 20, and a projection (not shown) protruding from the plate portion 34 toward the outside of the battery case 20. )have. The plate portion 34 is provided with a through hole 32 through which the shaft portion 12 of the negative electrode internal terminal 10 (the non-deformed negative internal terminal 10a shown in FIG. 2) before caulking can be inserted. The through hole 32 is formed at a position corresponding to the through hole 22 of the battery case 20 and has an inner diameter of a size that fits the shaft portion 12 of the negative electrode internal terminal 10. As a constituent material of the negative electrode external terminal 30, a metal material such as aluminum can be preferably adopted.

<Insulator>
The insulator 50 is a member that insulates the negative electrode external terminal 30 and the battery case 20. The insulator 50 is disposed on the outer surface of the battery case 20 located on the outside of the battery. The insulator 50 has a through hole 52 at a position corresponding to the through hole 22 of the battery case 20. The through hole 52 has an inner diameter of such a size as to fit the shaft portion 12 of the negative electrode internal terminal 10. The insulator 50 is compressed in the axial direction of the shaft 12 by being pinched between the battery case 20 and the negative electrode external terminal 30 by caulking the negative electrode internal terminal 10 so as to surround the through hole 52. As a constituent material of insulator 50, resin materials, such as polyphenylene sulfide resin (PPS) and aliphatic polyamide, can be adopted preferably.

<Gasket>
The gasket 40 is provided with a through hole 42 through which the shaft portion 12 of the negative electrode internal terminal 10 (the non-deformed negative internal terminal 10 a shown in FIG. 2) is crimped. In the gasket 40, the portion surrounding the through hole 42 is sandwiched between the battery case 20 and the pedestal portion 14 of the negative electrode internal terminal 10 and compressed so that the negative electrode internal terminal 10 (pedestal portion 14) and the battery case 20 And the through hole 22 of the battery case 20 is sealed. The gasket 40 has a cylindrical portion 44 which is inserted from the inside into the through hole 22 of the battery case 20 and prevents (insulates) direct contact between the shaft portion 12 of the negative electrode internal terminal 10 and the battery case 20. The cylindrical portion 44 has a hollow cylindrical shape. The cylindrical portion 44 is provided such that its outer peripheral surface is in contact with the inner peripheral surface of the through hole 22 and its inner peripheral surface is in contact with the outer peripheral surface of the shaft 12 of the negative electrode internal terminal 10. As a constituent material of the gasket 40, various resin materials exhibiting resistance to the electrolyte to be used can be appropriately selected and used. For example, fluorinated resin such as perfluoroalkoxy fluorine resin (PFA), polyphenylene sulfide resin (PPS), polyimide resin, polyamide imide resin, polyether ether ketone resin (PEEK), polyether ketone ketone resin (PEKK), polyether sulfone A resin material such as resin (PES) can be employed.

<Negative internal terminal>
The negative electrode internal terminal 10 is made of a conductive material such as a metal material (copper or aluminum). The negative electrode internal terminal 10 is inserted into the through hole 22 provided in the battery case 20. The negative electrode internal terminal 10 is connected to the negative electrode external terminal 30 outside the battery case 20, and is electrically connected to the electrode body inside the battery case 20. The negative electrode internal terminal 10 electrically connects the negative electrode external terminal 30 to the electrode body.

  FIG. 2: is an exploded view which shows typically each member before the crimping process mentioned later. In the embodiment shown in FIG. 1 and FIG. 2, the negative electrode internal terminal 10 (non-deformed negative internal terminal 10 a) has the shaft portion 12 penetrating the battery case 20 and the negative electrode external terminal 30 and the outer peripheral surface of one end of the shaft portion 12 And a pedestal portion 14 provided on the The shaft portion 12 is inserted into the through hole 22 of the battery case 20 and extends through the battery case 20 in the axial direction. The shaft portion 12 is further inserted through the through hole 52 of the insulator 50 and the through hole 32 of the negative electrode external terminal 30 outside the battery case 20, and penetrates the insulator 50 and the negative electrode external terminal 30 in the axial direction. The pedestal portion 14 is provided on the outer peripheral surface of one end portion of the shaft portion 12 in the battery case 20. The pedestal portion 14 has a bowl shape extending in a direction orthogonal to the axial direction of the negative electrode internal terminal 10. In this embodiment, the pedestal 14 extends substantially in parallel with the inner surface of the battery case (here, the lid) 20 and is disposed between the battery case 20 and the electrode body.

<Screw processing>
The negative electrode internal terminal 10 and the negative electrode external terminal 30 are fixed to the battery case 20 by caulking (revetting) the negative electrode internal terminal 10 to the negative electrode external terminal 30. A caulking portion 16 is formed by caulking on the tip of the negative electrode internal terminal 10 (shaft portion 12) in FIG.

  FIG. 3 is a cross-sectional view for explaining caulking processing of the negative electrode internal terminal 10 (non-deformed negative internal terminal 10a) according to one embodiment. In order to crimp the negative internal terminal 10, first, the shaft 12 of the non-deformed negative internal terminal 10a, which is the negative internal terminal 10 that has not been crimped, is processed by the negative external terminal 30, the insulator 50, and the battery. The battery case 20 is protruded to the outside of the battery case 20 so as to penetrate the laminated portion in which the case 20 and the gasket 40 are laminated. Then, using the rotary caulking machine 60 having the rotary head 62, the end portion of the tip end portion of the non-deformed negative internal terminal 10 which is protruded and opposite to the side where the pedestal portion 14 of the shaft portion 12 is positioned The caulking portion 16 is formed by caulking at the peripheral portion surrounding the through hole 32 of the negative electrode external terminal 30, and the insulator 50 is compressed between the battery case 20 and the negative electrode external terminal 30, Negative electrode external terminal 30, battery case 20, insulator 50, and negative electrode internal terminal 10 are integrally fixed. Further, the gasket 40 is compressed between the battery case 20 and the pedestal portion 14 by the caulking process, whereby the through hole 22 of the battery case 20 is sealed.

  FIG. 4 is an enlarged view of a peripheral edge portion 16 a in the radial direction of the shaft portion 12 of the caulking portion 16 according to an embodiment formed by caulking and a central portion 16 b in the radial direction of the shaft portion 12 of the caulking portion 16. FIG. Hereinafter, the “peripheral edge portion 16 a of the caulking portion 16” refers to the peripheral edge portion 16 a in the radial direction of the shaft portion 12 of the caulking portion 16. The shape of the caulking portion 16 will be briefly described with reference to FIG.

In the peripheral portion 16a of the caulking portion 16, and the negative electrode external terminal 30 (plate portion 34) is the distance the edge height h _a of the surface opposite to the side where it is located to the plate portion 34 of the caulking portion 16. Further, the distance from the outermost position in the radial direction of the shaft portion 12 of the caulking portion 16 to the plate portion 34 is taken as the outermost circumference height h _b . The length of the caulking portion 16 protruding outward in the radial direction of the shaft portion 12 from the position where the caulking portion 16 and the plate portion 34 of the negative electrode external terminal 30 are in close contact is an edge length d. Further, the distance from the position most distant from the plate portion 34 to the plate portion 34 in the radial central portion 16 b of the shaft portion 16 of the caulking portion 16 is taken as the caulking height h _c . Further, FIG. 6 described later shows a caulking diameter e which is a diameter in the radial direction of the shaft portion 12 of the caulking portion 16.

As will be described later in detail, from the viewpoint of improving the conductivity between the negative electrode internal terminal 10 and the negative electrode external terminal 30 by welding, caulking is performed so that the edge height h _a is 0.1 mm or more and 0.55 mm or less. Preferably it is The sizes of the outermost circumferential height h _b , edge length d, caulking height h _c and caulking diameter e are not particularly limited. Usually, the caulking portion 16 has a shape satisfying h _b <h _a <h _c as shown in FIG. 4 by the caulking process described above.

<Welding process>
The negative electrode internal terminal 10 in which the caulking portion 16 is formed by caulking is then welded to the plate portion 34 of the negative electrode external terminal 30. 5 and 6 are a cross-sectional view and a plan view for explaining the welding process of the negative electrode internal terminal 10 and the negative electrode external terminal 30 according to one embodiment, and FIG. 7 is a VII-VII 'line in FIG. FIG. As shown in FIGS. 5, 6 and 7, the peripheral portion 16 a of the caulking portion 16 is welded to the negative electrode external terminal 30. Preferably, continuous oscillation is performed in the vicinity of the peripheral portion 16a of the caulking portion 16 (a region extending from the peripheral portion 16a of the caulking portion 16 to the plate portion 34 located on the outer side thereof (radially outer side of the shaft portion 16)) The laser beam La is irradiated, and the laser beam La further travels along the outer edge of the caulking portion 16 so that welding (laser welding) is performed on the entire periphery of the caulking portion 16.

  FIG. 7 is an enlarged view of the peripheral portion 16 a of the caulking portion 16 after the welding process. A welded portion 70 is formed on the peripheral portion 16 a of the caulking portion 16 by welding. As shown in FIG. 7, the length of the welded portion 70 in the boundary region between the negative electrode internal terminal 10 and the negative electrode external terminal 30 after welding is taken as the welded portion length f. After the caulking portion 16 is subjected to the welding process, the conduction area between the negative electrode internal terminal 10 and the negative electrode external terminal 30 can be calculated by measuring the welded portion length f. The conduction area can be an indicator of the conduction between the negative electrode internal terminal 10 and the negative electrode external terminal 30.

Here, the present inventors control the shape of the caulking portion 16 of the negative electrode internal terminal 10 (in particular, the shape of the peripheral portion of the caulking portion 16), thereby the caulking portion 16 of the negative electrode internal terminal 10 and the negative electrode external terminal 30 ( It has been found that the conductive area between the two terminals by welding with the plate portion 34) is increased. According to the disclosed technique, edge height _{h a} of the caulking portion 16 is preferably not more than 0.55 mm. When the edge height h _a is not more than 0.55 mm, even if variation in the example the shape or size of the weld 70 formed by welding, stable during the negative internal terminal 10 and the negative electrode external terminal 30 A conduction area large enough to realize low resistance can be realized. Further, it is preferable that the edge height _{h a} is 0.1mm or more. When the edge height h _a is too small than 0.1 mm, the influence of heat is likely to extend to peripheral components that may occur during the laser welding process.

As a method of controlling the edge height h _a of the caulking portion 16 is not particularly limited. As shown in FIG. 3, in the case of performing a caulking process in which the tip portion of the non-deformed negative internal terminal 10 a is caulked and deformed using the rotary caulking machine 60 having the rotary head 62, the bottom dead center of the rotary caulking machine 60 is controlled by, it is possible to realize the edge height h _a of the preferred range. Specifically, as lowering the bottom dead center of the rotary swaging machine 60, the edge height h _a tends to decrease.

  Hereinafter, test examples relating to the present invention will be described, but the following description is not intended to limit the present invention.

  As shown in FIG. 2, a battery case (a lid in this case) 20 was prepared, and a gasket 40 was set on the inner side, and an insulator 50 and a negative electrode external terminal 30 were set on the outer side. Then, the undeformed negative internal terminal 10a before caulking is prepared, and its shaft portion 12 is sequentially inserted through the through hole 22 of the battery case 20, the through hole 42 of the gasket 40, and the through hole 32 of the negative electrode external terminal 30. The battery case 20 and the negative electrode external terminal 30 were penetrated. Then, a load is applied to the gasket 40 and the insulator 50 from the side of the negative electrode external terminal 30 using a pressing jig, and the load is applied to the tip portion of the shaft portion 12 of the non-deformed negative internal terminal 10a. The end on the side opposite to the side where the pedestal portion 14 is positioned is protruded outward from the through hole 32 of the negative electrode external terminal 30. In that state, as shown in FIG. 3, the end of the protruding shaft portion 12 is radially expanded using a rotary caulking machine 60 having a rotary head 62 to surround the through hole 32 of the negative electrode external terminal 30. The negative electrode external terminal 30 was attached to the through hole 22 of the battery case 20 by caulking on the peripheral portion (crimping process) to construct an assembly.

  In the caulking process, the setting of the bottom dead center of the rotary caulking machine 60 was changed up and down to perform caulking, and the shape of the caulking portion 16 formed after caulking was observed. Table 1 shows an example 1 where the bottom dead center of the rotary caulking machine 60 is set relatively lower and the caulking process is performed, and the lower dead center of the rotary caulking machine 60 is set relatively upper and the caulking process is performed. The result of having observed the shape of caulking part 16 is shown about Example 2 performed.

As shown in Table 1, it was confirmed that the shape of the caulking portion 16 (particularly, the edge height _ha ) can be controlled by controlling the bottom dead center of the rotary caulking machine 60. Result of performing a plurality of times such tests, as lowering the bottom dead center of the rotary swaging machine 60, the edge height h _a of the caulking portion 16 was confirmed to be prone to decrease.

Next, with respect to the assembly subjected to caulking, the peripheral edge portion 16a of the caulking portion 16 and the negative electrode external terminal 30 were joined by laser welding all around. The peripheral portion 16a of the crimped portion 16 after welding was observed, the weld length f (FIG. 7) was measured, and the conduction area was calculated from the weld length f. The results are shown in Table 1 and FIG. Incidentally, FIG. 8 is a graph showing the relationship between the edge height _h a [mm] and conduction area of the crimped portion 16 [mm ^2].

Table 1 and is apparent from the results shown in FIG. 8, as the edge height h _a of the caulking portion is small, the conduction area was improved. Here, if the conduction area is about 0.6 mm ² or more, low resistance between the negative electrode internal terminal 10 and the negative electrode external terminal 30 can be stably achieved even if the welding quality varies in the welding process, for example. It can be said that Building from the results shown in Figure 8, the edge height h _a of the caulking portion 16 is less than 0.55 mm, the conduction area generally becomes 0.6 mm ² or more, a sealed battery having a practically suitable stable quality It turns out that you can do it.

  Although the specific examples of the present invention have been described above in detail, these are merely examples and do not limit the scope of the claims. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 10 negative internal terminal 12 axial part 14 base part 16 caulking part 20 battery case 22 through hole 30 negative electrode external terminal 32 through hole 34 plate part 40 gasket 42 through hole 50 insulator 52 through hole 60 rotary caulking machine 62 rotary head 100 sealed type battery

Claims (1)

An electrode body comprising a positive electrode and a negative electrode;
A battery case for housing the electrode body;
Internal terminals of positive and negative electrodes electrically connected to the positive and negative electrodes inside the case;
Positive and negative external terminals provided on the outside of the case and electrically connected to the positive and negative internal terminals respectively;
A sealed battery comprising:
The negative external terminal is
It has a plate portion formed in a direction along the outer wall of the case,
The negative internal terminal is
A pedestal located inside the case,
A shaft portion provided so as to protrude from the pedestal portion and pass through the through hole of the case and the through hole of the plate portion;
It is provided at the end opposite to the side where the pedestal portion of the shaft portion is located, and is formed by caulking at the peripheral portion surrounding the through hole of the plate portion by protruding outward from the through hole of the plate portion With caulking part,
Have
A peripheral edge portion in a radial direction of the shaft portion of the caulking portion is welded to the plate portion;
Said welding is under the following conditions:
In the periphery of the caulking portion, and the side of the plate portion of the caulking portion is located a distance h _a from the surface opposite to said plate portion, is 0.1mm or 0.55mm or less;
A sealed battery characterized in that it is performed on the crimped portion satisfying the following conditions.

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