JP7434211B2 - battery - Google Patents

Description

The present invention relates to a battery equipped with a current collecting structure.

Batteries such as lithium ion secondary batteries and alkaline secondary batteries are equipped with a current collection structure for extracting current from an electrode body to the outside and supplying current from the outside to the electrode body (for example, a patented (See Reference 1). The current collection structure includes a current collection terminal made of a metal material that is electrically connected to the electrode body, and an external terminal provided on the outside of the case of the secondary battery. One end of the current collector terminal is connected to the electrode body. The other end of the current collector terminal is caulked to the external terminal. The external terminal has a recess that accommodates the caulked portion of the current collector terminal. Further, the caulked portion of the current collector terminal is welded to the external terminal. As a result, a current path consisting of the electrode body, current collecting terminal, and external terminal is formed.

Furthermore, in order to obtain desired power, a battery pack in which a plurality of batteries are combined is sometimes used. The current collecting structures of the batteries constituting the assembled battery are connected to the current collecting structures of adjacent batteries by bus bars made of metal material. The assembled battery is used, for example, as a power source for a vehicle such as an electric vehicle or a hybrid vehicle.

JP2020-95837A

In a current collecting structure in which a caulked portion is accommodated in a recess formed in an external terminal, a portion of the caulked portion may protrude from the surface of the external terminal. When the caulked portion protrudes from the surface of the external terminal, restrictions arise in arranging or designing the bus bar so as to avoid the caulked portion protruding from the recess, reducing the degree of freedom in design. Further, even for batteries other than batteries constituting an assembled battery, it is not preferable for the caulked portion to protrude from the surface of the external terminal because it may interfere with external members.

A battery that solves the above problems has an external terminal and a current collector made of a metal material, having one axial end electrically connected to an electrode body and the other end having a caulked part in contact with the external terminal. the external terminal includes a recess having an opening and a bottom surface and accommodating the caulking portion; and a recess formed in the bottom surface of the recess, the recess extending from the opening to the The side surface has an inclined surface that is inclined so that the diameter of the recessed portion decreases toward the bottom surface.

According to the above configuration, since the recess is formed on the bottom surface of the recess, the volume into which the metal material of the current collector terminal is press-fitted can be increased. Furthermore, since the side surfaces of the recess are inclined, a metal material is likely to be press-fitted into the recess when crimping the current collector terminal. Therefore, it is possible to prevent the caulked portion from protruding from the surface of the external terminal.

In the above battery, it is preferable that the recess is provided continuously on the inclined surface.
According to the above configuration, since the slope and the recess are provided continuously, the metal material is easily press-fitted into the recess along the slope. Therefore, the recess can be filled with the metal material almost without any gaps.

In the battery described above, it is preferable that the recess has an annular shape.
According to the above configuration, since the metal material wraps around the annular recess, the recess can be filled with the metal material almost without any gaps.

In the battery described above, it is preferable that the recessed portion has a plurality of linear portions that radially extend from the center of the bottom surface of the recessed portion toward the inclined surface.
According to the above configuration, since the metal material can be press-fitted into the linear portions extending in different directions, it is easy to fill the hollow portion with the metal material.

In the battery described above, it is preferable that the recess is a groove formed in the bottom surface of the recess.
According to the above configuration, since the recess is formed in the shape of a groove on the bottom surface of the recess, the strength of the bottom surface of the recess can be maintained satisfactorily.

According to the present invention, the degree of freedom in designing the current collection structure can be increased by suppressing the protrusion of the caulked portion of the current collection terminal from the external terminal.

1 is a diagram schematically showing a perspective structure of an embodiment of a secondary battery; FIG. FIG. 3 is a cross-sectional view of the current collection structure in the same embodiment. FIG. 3 is a plan view of the current collection structure in the same embodiment. FIG. 3 is a cross-sectional view of the current collection structure in the same embodiment. FIG. 3 is a cross-sectional view of a current collection structure in another embodiment. FIG. 7 is a cross-sectional view of a part of a current collecting structure in another embodiment. FIG. 7 is a cross-sectional view of a part of a current collecting structure in another embodiment. FIG. 7 is a plan view of a recessed portion of an external terminal in another embodiment. FIG. 7 is a plan view of a recessed portion of an external terminal in another embodiment.

One embodiment of the battery will be described according to FIGS. 1 to 4. In this embodiment, an example will be described in which the battery is a lithium ion secondary battery installed in a vehicle such as an electric vehicle or a hybrid vehicle.

As shown in FIG. 1, a battery module 11 as a secondary battery includes a case 12, a lid 13, and an electrode body 14. The case 12 and the lid part 13 are made of metal material. The case 12 has an opening, and the lid 13 seals the opening. An internal space 15 formed by the case 12 and the lid 13 accommodates an electrode body 14 and an electrolyte.

The lid portion 13 is provided with a positive electrode current collector 32 and a negative electrode current collector 31, which are current collecting structures. Further, the lid portion 13 is provided with a gas exhaust valve 24 that releases gas from the internal space 15 according to the pressure of the internal space 15, and a liquid injection port 25 that injects electrolyte. Hereinafter, when the positive electrode current collector 32 and the negative electrode current collector 31 are to be described without distinguishing them, they will be simply referred to as the current collector 30.

The electrode body 14 is a laminate in which a plurality of negative electrode plates 18 and a plurality of positive electrode plates 19 are alternately laminated with separators (not shown) interposed therebetween. The positive electrode plate 19 includes a base material made of a metal material such as aluminum or an aluminum alloy, and a positive electrode mixture provided on the base material. The positive electrode mixture includes a lithium-containing composite oxide as a positive electrode active material, a binder, a conductive agent, and the like. The base material of the positive electrode plate 19 is provided with a positive electrode tab 19A extending from the end.

The negative electrode plate 18 includes a base material made of copper and a negative electrode mixture provided on the base material. The negative electrode mixture includes, for example, a negative electrode active material such as a carbon material, a binder, a conductive agent, and the like. The base material of the negative electrode plate 18 is provided with a negative electrode tab 18A extending from the end.

The negative electrode plate 18 and the positive electrode plate 19 are stacked with the negative electrode tab 18A and the positive electrode tab 19A aligned in position, respectively. The negative electrode tabs 18A of the plurality of negative electrode plates 18 are collected into a bundle to form a negative electrode tab group 22. The plurality of positive electrode tabs 19A are collected into a bundle to form a positive electrode tab group 23. The negative electrode tab group 22 is electrically connected to the negative electrode current collector 31 , and the positive electrode tab group 23 is electrically connected to the positive electrode current collector 32 .

The plurality of battery modules 11 constitute a battery pack. The positive electrode current collector 32 of the battery module 11 is connected to the negative electrode current collector 31 of the adjacent battery module 11 via a bus bar (not shown). Further, the negative electrode current collector 31 of the battery module 11 is connected to the positive electrode current collector 32 of the adjacent battery module 11 via a bus bar.

With reference to FIG. 2, the configuration of the current collecting structure 10 in the current collecting section 30 will be described. Since the structures of the negative electrode current collector 31 and the positive electrode current collector 32 are similar, the structure of the negative electrode current collector 31 will be described here. The negative electrode current collector 31 includes a current collector terminal 35, a gasket 36, an insulator 37, and an external terminal 38. In this embodiment, the negative electrode current collector terminal 35 is made of copper or a copper-based material, similar to the base material of the negative electrode plate 18. Further, the external terminal 38 and the bus bar are made of aluminum or an aluminum-based material.

The gasket 36 is made of an insulating material such as resin, has a cylindrical shape, and has a through hole 36A inside. The gasket 36 is provided inside the through hole 13C provided in the lid portion 13. Further, the insulator 37 and the external terminal 38 are provided on the surface 13A side of the lid portion 13.

The insulator 37 is made of an insulating material such as resin, is interposed between the external terminal 38 and the lid 13, and insulates the external terminal 38 and the lid 13. Further, the insulator 37 is provided with a through hole 37A.

The external terminal 38 includes a recess 40 that accommodates the caulked portion of the current collecting terminal 35. The recess 40 is open at the surface 38A and has a circular shape when viewed from the surface 38A side. A through hole 38B is provided in the bottom surface 42 of the recess 40. The external terminal 38 is arranged such that the through hole 38B is aligned with the through hole 37A of the insulator 37, the through hole 36A of the gasket 36, and the through hole 13C of the lid portion 13.

Furthermore, a recessed portion 43 is formed in the bottom surface 42 of the recessed portion 40 . The recessed portion 43 is formed in the shape of a groove on the bottom surface 42 of the external terminal 38 . The surface 38A of the external terminal 38 and the bottom surface 42 of the recess 40 are connected by an inclined surface 44. In other words, the side surface of the recess 40 is an inclined surface 44. The sloped surface 44 is sloped so that the inner diameter of the recess 40 decreases from the opening 40A of the recess 40 toward the bottom surface 42. The angle of inclination of the inclined surface 44 is constant. Further, the inclined surface 44 and the recessed portion 43 are continuous.

The current collector terminal 35 is inserted through the through hole 38B of the external terminal 38, the through hole 37A of the insulator 37, and the through hole 36A of the gasket 36. One end of the current collector terminal 35 protrudes into the internal space 15 formed by the case 12 and the lid 13.

One end of the current collecting terminal 35 is connected to the electrode body 14 (see FIG. 1) via a connecting member 50. The current collector terminal 35 includes a caulked portion 41 at the other end. The caulking portion 41 is a substantially disk-shaped portion having an outer diameter larger than the inner diameter of the through hole 38B. The caulking portion 41 is formed by pressing and caulking the end of the current collecting terminal 35 toward the recess 40 , and is accommodated in the recess 40 of the external terminal 38 .

A protrusion 45 is formed on the bottom surface of the caulking part 41. The protrusion 45 is formed by press-fitting a metal material forming the current collecting terminal 35 into the recess 43 . The protrusion 45 fits into the recess 43 of the external terminal 38. The protrusion 45 and the depression 43 have a concave-convex structure that fits into each other.

A portion of the caulked portion 41 is joined to the external terminal 38 by welding or brazing such as FSW (Friction Stir Welding), laser welding, arc welding, and ultrasonic welding. In this way, the insulator 37 and the external terminal 38 are held between the caulking part 41 and the lid part 13. Although an adhesive layer is not provided between the insulator 37 and the lid portion 13 and between the insulator 37 and the external terminal 38, an adhesive layer may be provided to suppress displacement of each member.

The current collector terminal (not shown) of the positive electrode current collector 32 differs from the negative electrode current collector 31 in that, like the base material of the positive electrode plate 19, it is made of aluminum or an aluminum-based material. That is, the external terminal (not shown), the current collecting terminal (not shown), and the bus bar of the positive electrode current collector 32 are made of the same material or the same material.

FIG. 3 is a plan view of a portion of the external terminal 38 that includes the recess 40, and shows a state in which the current collecting terminal 35 is not attached. The recessed portion 43 has an annular shape surrounding the through hole 38B when viewed from above.

The current collecting structure of this embodiment will be described in detail along with its function. Since the actions in the negative electrode current collector 31 and the actions in the positive electrode current collector 32 are similar, the negative electrode current collector 31 will be explained. Before the current collecting terminal 35 is caulked, the end portion 35A of the current collecting terminal 35 protrudes from the recess 40. The end portion 35A of the current collecting terminal 35 is provided with a hole portion 35C into which the jig 51 is inserted. By inserting the jig 51 into the hole 35C and rotating the jig 51 while press-fitting it, the end portion 35A of the current collecting terminal 35 is plastically deformed. At this time, the end portion 35A of the current collecting terminal 35 receives the pressing force of the jig 51, expands in the radial direction perpendicular to the axial direction of the end portion 35A, and is pressed against the inclined surface 44. The metal material pressed against the slope 44 deforms along the slope 44 and enters the recess 43. Since the recess 43 has an annular shape, the metal material is easily press-fitted into the recess 43 when it expands in the radial direction.

Further, since a bus bar is connected to the external terminal 38, external force may be applied via the bus bar due to vibration, sudden acceleration/deceleration, etc. Since the current collecting terminal 35 and the external terminal 38 are fixed to each other by bonding, the current collecting terminal 35 and the external terminal 38 are difficult to come off. In this embodiment, in addition to the structure, since the protrusion 45 of the caulking part 41 of the current collecting terminal 35 and the recessed part 43 of the external terminal 38 form an uneven structure, there is a gap between the current collecting terminal 35 and the external terminal 38. Even if an external force is applied in a direction parallel to the surface 13A of the lid portion 13, the current collecting terminal 35 and the external terminal 38 are hardly displaced.

The effects of the above embodiment will be explained.
(1) Since the recess 43 is formed in the bottom surface 42 of the recess 40 of the external terminal 38, the volume into which the metal material of the current collector terminal 35 is press-fitted can be increased. Furthermore, since the side surfaces of the recess 40 are inclined, a metal material is likely to be press-fitted into the recess 43 when the current collector terminal 35 is caulked. Therefore, the caulking portion 41 can be prevented from protruding from the surface 38A of the external terminal 38.

(2) Since the slope 44 and the recess 43 are provided continuously, the metal material is easily press-fitted into the recess 43 along the slope 44. Therefore, the recessed portion 43 can be filled with the metal material almost without any gaps.
(3) Since the metal material wraps around the annular recess 43, the recess 43 can be filled with the metal material almost without any gaps.

(4) Since the recess 43 is formed in the shape of a groove on the bottom surface 42 of the recess 40, the strength of the bottom surface 42 of the recess 40 can be maintained better than when the recess 43 is formed by cutting out the bottom surface 42. I can do it.

The above embodiment can be modified and implemented as follows. The above embodiment and the following modification examples can be implemented in combination with each other within a technically consistent range.
- In the above embodiment, the end portion 35A of the current collector terminal 35 protruding from the surface 13A of the lid portion 13 is caulked. Alternatively or in addition to this, as shown in FIG. 5, by caulking the end portion 35B of the lid portion 13 that protrudes from the back surface 13B, which is the surface opposite to the front surface 13A, the current collecting terminal 35 is closed to the lid. It may also be attached to the section 13. In this case, the lid 13 is attached to the case 12 after the end 35B is caulked on the back surface 13B. External terminal 38 is attached inside gasket 36. The external terminal 38 has the same configuration as in the above embodiment. Also in this case, it is possible to prevent the current collecting terminal 35 from protruding from the surface 38A of the external terminal 38. Therefore, the protruding portion of the current collecting terminal 35 is prevented from coming into contact with the connecting member 50 joined to the external terminal 38, so that restrictions on the layout and shape of the connecting member 50 can be reduced.

- In the above embodiment, the inclined surface 44 is a plane having a constant inclination angle. Alternatively, as shown in FIG. 6, the recess 40 may be provided with an inclined surface 46 that is a curved surface.
- In the above embodiment, the recessed portion 43 has a groove-like shape. Alternatively or in addition to this, the recessed portion 48 may be formed by providing a step at the lower end of the inclined surface 44, as shown in FIG. According to this configuration, the volume of the recessed portion 43 can be increased.

- The recessed portion 43 may have any shape as long as it is formed on the bottom surface of the recessed portion 40 and into which a metal material can be press-fitted, and is not limited to the shape and number of the above embodiment. As shown in FIG. 8, a plurality of arcuate recesses 52 may be arranged around the through hole 38B. In the example of FIG. 8 , a pair of recesses 52 are located on the bottom surface 42 . Further, as shown in FIG. 9, a plurality of linear recesses 53 may be provided around the through hole 38B. The recessed portion 53 serving as a linear portion extends radially around the through hole 38B located at the center of the bottom surface 42 of the recessed portion 40. According to this configuration, since the metal material can be press-fitted into the recesses 53 extending in different directions, it is easy to fill the recesses with the metal material.

- In each of the above embodiments, the electrode body 14 of the battery module 11 has a laminated structure in which a plurality of negative electrode plates 18 and a plurality of positive electrode plates 19 are alternately laminated with separators interposed therebetween. Alternatively, the electrode body 14 may have a wound structure in which a long positive electrode plate and a long negative electrode plate are wound flat with a long separator in between. Further, the secondary battery may be other than the battery module 11, and may be a module including a plurality of cells, for example. In short, any material that includes the positive electrode current collector 32 and the negative electrode current collector 31 and can charge and discharge the electrode body is sufficient.

- The battery module 11 may be used in vehicles such as electric cars, hybrid cars, gasoline cars, and diesel cars, and other moving objects. Alternatively, it may be a secondary battery for household or industrial use.

- In the above embodiment, the battery module 11 was described as a lithium ion secondary battery including a positive electrode composite material containing a lithium-containing composite oxide and a negative electrode composite material containing a carbon material, but it is limited to a lithium ion secondary battery. However, batteries having other positive electrode composite materials and negative electrode composite materials such as nickel-metal hydride secondary batteries may also be used. Further, the battery module 11 having the current collecting structure 10 described above is not limited to a square shape but may be a cylindrical shape.

DESCRIPTION OF SYMBOLS 11... Battery module 35... Current collector terminal 38... External terminal 40... Recessed part 41... Caulked part 43, 48... Recessed part 44, 46... Inclined surface

Claims (5)

external terminal and
a current collector terminal made of a metal material, one end in the axial direction electrically connected to the electrode body, and the other end having a caulked part in contact with the external terminal,
The external terminal is
a recessed portion having an opening and a bottom surface and accommodating the caulking portion;
and a recess formed on the bottom surface of the recess,
In the battery, the recess has an inclined surface on a side surface that is inclined so that the diameter of the recess decreases from the opening toward the bottom surface. The battery according to claim 1, wherein the recess is provided continuously on the inclined surface. The battery according to claim 1 or 2, wherein the recess has an annular shape. The battery according to claim 1 or 2, wherein the recessed portion has a plurality of linear portions that extend radially from the center of the bottom surface of the recessed portion toward the inclined surface. The battery according to any one of claims 1 to 4, wherein the recess is a groove formed on the bottom surface of the recess.