CN118156736B

CN118156736B - Battery monomer and battery pack

Info

Publication number: CN118156736B
Application number: CN202410566647.4A
Authority: CN
Inventors: 李金成; 孙超; 周杰; 贡伟红
Original assignee: Svolt Energy Technology Co Ltd
Current assignee: Svolt Energy Technology Co Ltd
Priority date: 2024-05-09
Filing date: 2024-05-09
Publication date: 2024-07-09
Anticipated expiration: 2044-05-09
Also published as: CN118156736A

Abstract

The invention relates to the technical field of batteries, and discloses a battery monomer and a battery pack, comprising the following components: a housing having an opening; the cover plate is arranged corresponding to the opening and connected with the shell so as to form an accommodating space in a surrounding way; the electrode group is arranged in the accommodating space and comprises an electrode lug, an ultrasonic welding mark is arranged on the electrode lug to be connected with the electrode lug which is arranged in a layered mode, the electrode lug and the cover plate are welded by laser to form a laser welding mark on the electrode lug, and the laser welding mark is positioned in the ultrasonic welding mark; the distances from the edge of the laser welding mark to the edge of the corresponding ultrasonic welding mark are a, b, c, d respectively, so that a is more than or equal to 0.5mm, b is more than or equal to 0.5mm, c is more than or equal to 0.5mm, and d is more than or equal to 0.5mm. According to the invention, the electrode lugs of each electrode plate are connected into a whole through ultrasonic welding, and then the electrode lugs are connected with the cover plate through laser welding, so that parts such as connecting sheets, electrode posts, lower plastic and the like are not required to be arranged, the utilization rate of the internal space of the battery is improved, the volume and the mass energy density of the battery are improved, and the explosion point generated by welding is avoided.

Description

Battery monomer and battery pack

Technical Field

The invention relates to the technical field of batteries, in particular to a battery monomer and a battery pack.

Background

The power battery has the advantages of high energy density, good safety, light weight, long cycle life and the like, and is widely applied to the energy storage system in the new energy automobile. In the existing battery, the tab of the pole group is welded with the connecting sheet, and then the connecting sheet is welded with the pole column of the battery cover plate, so that the electric connection between the pole group and the pole column is realized, and the transmission of electric energy in the pole group is realized. However, the existing connection method using the connection sheet causes a large occupation of the internal space of the battery in the height direction, so that the internal space utilization rate of the battery is low, and the energy density of the battery is reduced.

Disclosure of Invention

In view of this, the invention provides a battery cell and a battery pack, which solves the problems that the existing connection mode using the connection sheet occupies a larger internal space of the battery in the height direction, so that the utilization rate of the internal space of the battery is low and the energy density of the battery is reduced.

In a first aspect, the present invention provides a battery cell comprising: a housing having an opening and being hollow inside; the cover plate is arranged corresponding to the opening and connected with the shell so as to form an accommodating space in a surrounding way; the electrode group is arranged in the accommodating space and comprises an electrode lug, ultrasonic welding marks are arranged on the electrode lug to be connected with the electrode lug which is arranged in a layered mode, the electrode lug and the cover plate are welded through laser to form laser welding marks on the electrode lug, and the laser welding marks are positioned in the ultrasonic welding marks; the distances from the edge of the laser welding mark to the corresponding edge of the ultrasonic welding mark are a, b, c, d respectively, so that a is more than or equal to 0.5mm, b is more than or equal to 0.5mm, c is more than or equal to 0.5mm, and d is more than or equal to 0.5mm.

The beneficial effects are that: the electrode lugs on each electrode plate are connected into a whole through ultrasonic welding, then the electrode lugs are connected with the cover plate through laser welding, the cover plate is connected with the shell, and parts such as connecting sheets, electrode posts and lower plastic are not required to be arranged, so that the utilization rate of the internal space of the battery is improved, the volume and the mass energy density of the battery are improved, and the quality of the battery can be reduced and the cost is reduced after the parts such as the connecting sheets, the electrode posts and the lower plastic are omitted; the tab is still in a layered state in the area except the ultrasonic welding, the distance between two adjacent layers is large, the tab and the cover plate cannot be connected through laser welding in the area except the ultrasonic welding, and a frying point is easy to generate.

In an alternative embodiment, along the length direction of the tab, the minimum distances from the edge of the ultrasonic welding to the edge of the corresponding tab are i and j, respectively, so that i is greater than or equal to 1.5mm, and j is greater than or equal to 1.5mm.

The beneficial effects are that: the welding head is prevented from being influenced greatly by uneven stress and the service life of the welding head, and the welding quality is ensured.

In an alternative embodiment, the width e of the ultrasonic welding is 4mm to 20mm along the height direction of the tab.

The beneficial effects are that: the electrode lug is prevented from being torn while the laser welding is performed with enough width, and the safety of the battery monomer is ensured.

In an alternative embodiment, the effective penetration f at the welded connection of the tab and the cover plate is 50 μm to 900 μm.

In an alternative embodiment, the effective welding width g of the welding connection of the tab and the cover plate is at least 1.5mm.

In an optional implementation manner, the battery unit further comprises an end plate, the end plate is arranged between the end face of the pole group and the cover plate, a through groove is formed in the end plate, a guide surface is further formed on the end plate, the tab penetrates through the through groove and then is bent to be close to or fit with the guide surface, and the tab is connected with the cover plate in a fit mode after being bent for many times.

In an alternative embodiment, the cover plate has a width of 13mm to 40mm and a length of 80mm to 300mm.

In an alternative embodiment, the length of the battery cell is 300mm to 1200mm.

In a second aspect, the invention also provides a battery pack, which comprises the battery cell.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of the structure of ultrasonic and laser welding according to an embodiment of the present invention;

Fig. 2 is a schematic diagram of a fitting structure of a tab, an end plate and a cover plate according to an embodiment of the present invention.

Reference numerals illustrate:

1. A pole group; 11. a tab; 2. ultrasonic welding; 3. laser welding; 4. a cover plate; 5. an end plate; 51. a through groove; 52. and a guide surface.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

An embodiment of the present invention is described below with reference to fig. 1 and 2.

According to an embodiment of the present invention, in one aspect, there is provided a battery cell including: a housing, a cover plate 4 and a pole group 1. The inside cavity of casing sets up and has the opening, and apron 4 corresponds the opening setting and is connected with the casing to enclose and close and form accommodation space, utmost point group 1 sets up in accommodation space. The electrode group 1 comprises an electrode lug 11, an ultrasonic welding stamp 2 is arranged on the electrode lug 11 to be connected with the electrode lug 11 which is arranged in a layered mode, the electrode lug 11 and the cover plate 4 are welded through laser to form a laser welding stamp 3 on the electrode lug 11, and the laser welding stamp 3 is located in the ultrasonic welding stamp 2.

The lug 11 on each pole piece is connected into a whole through ultrasonic welding, the lug 11 is connected with the cover plate 4 through laser welding, the cover plate 4 is connected with the shell, parts such as a connecting sheet, a pole post and lower plastic are not required to be arranged, the utilization rate of the internal space of the battery is improved, the volume and the mass energy density of the battery are improved, and the quality of the battery can be reduced and the cost is reduced after parts such as the connecting sheet, the pole post and the lower plastic are omitted.

It should be noted that, the electrode group 1 is generally formed by stacking a positive electrode sheet and a negative electrode sheet through winding or lamination, and therefore, the tab 11 is also a layered multi-layer structure, that is, the tab 11 includes a multi-layer copper foil or aluminum foil or other metal foil. The multi-layer foil of the tab 11 is welded into a whole through ultrasonic welding, so that the connection of the subsequent tab 11 and other parts is facilitated.

The cover plate 4 may be a metal plate, and further, may be an aluminum plate.

In one embodiment, the ultrasonic welding stamp 2 may be provided with one or several.

In one embodiment, as shown in FIG. 1, the distances from the edge of laser weld 3 to the edge of the corresponding ultrasonic weld 2 are a, b, c, d, respectively, satisfying a 0.5mm or more, b 0.5mm or more, c 0.5mm or more, and d 0.5mm or more. The tab 11 is still layered in the region other than the ultrasonic pad 2, the distance between the adjacent two layers is large, the tab 11 and the cover plate 4 cannot be connected by laser welding in the region other than the ultrasonic pad 2, and a burst point is likely to occur.

It should be noted that, referring to fig. 1, both the ultrasonic welding mark 2 and the laser welding mark 3 are rectangular structures, the length direction of the ultrasonic welding mark 2 is consistent with the length direction of the laser welding mark 3, the width direction of the ultrasonic welding mark 2 is consistent with the width direction of the laser welding mark 3, and the laser welding mark 3 is completely located in the ultrasonic welding mark 2. The distance between one long side of the laser welding mark 3 and one long side of the corresponding ultrasonic welding mark 2 is a, the distance between the other long side of the laser welding mark 3 and the other long side of the corresponding ultrasonic welding mark 2 is b, the distance between one short side of the laser welding mark 3 and the one short side of the corresponding ultrasonic welding mark 2 is c, and the distance between the other short side of the laser welding mark 3 and the other short side of the corresponding ultrasonic welding mark 2 is d, so that a is more than or equal to 0.5mm, b is more than or equal to 0.5mm, c is more than or equal to 0.5mm, and d is more than or equal to 0.5mm.

It should be further noted that, the values of a, b, c, d may be all the same, may be partially the same, may be all different, and the value of a, b, c, d may be specifically designed according to actual needs.

It should be noted that, the length direction of the ultrasonic welding mark 2 and the laser welding mark 3 is the length direction of the tab 11, and the width direction of the ultrasonic welding mark 2 and the laser welding mark 3 is the height direction of the tab 11.

Referring to table 1, the welding conditions of the tab 11 and the cover plate 4 when a, b, c, d take different values are shown in table 1, wherein the examples refer to the battery whose a, b, c, d value meets the requirement of the present example, and the comparative example is the battery whose a, b, c, d value does not meet the requirement of the present example.

Table 1a, b, c, d examples and comparative examples with different values of welding results

It should be noted that, referring to table 1, in comparative examples 1 to 3, a, b, c, d has a value smaller than 0.5mm, the distance from the edge of the laser welding mark 3 to the edge of the corresponding ultrasonic welding mark 2 is too small, and during the welding process, the tooling cannot press the ultrasonic welding mark 2, so that a hole is formed near the edge of the ultrasonic welding mark 2, and welding is poor; in embodiments 1 to 7, a, b, c, d has a value not smaller than 0.5mm, so that the edge of the laser welding mark 3 has a sufficient distance to the edge of the corresponding ultrasonic welding mark 2, so that laser welding can be smoothly performed, welding defects cannot be caused, and welding quality is ensured.

In one embodiment, as shown in fig. 1, along the length direction of the tab 11, the minimum distances from the edge of the ultrasonic welding 2 to the edge of the corresponding tab 11 are i and j, respectively, so that i is greater than or equal to 1.5mm and j is greater than or equal to 1.5mm.

It should be noted that, referring to fig. 1, the edge of the tab is disposed obliquely with respect to the edge of the ultrasonic welding mark, so that different positions of the edge of the tab are different from the distance of the corresponding edge of the ultrasonic welding mark.

Referring to table 2, the welding conditions of the tab 11 and the cover plate 4 when i and j take different values are shown in table 2, wherein the examples refer to the batteries with i and j satisfying the requirements of the examples, and the comparative examples refer to the batteries with i and j not satisfying the requirements of the examples.

Table 2 i, examples and comparative examples with different values of j welding results

It should be noted that, referring to table 2, in comparative examples 1 to 5, i and/or j have a value smaller than 1.5mm, which results in ultrasonic welding 2 exceeding the range of tab 11 or falling on the staggered floor, so that the uneven stress of the welding head has a greater influence on the service life of the welding head; in examples 1 to 4, the values of i and j are not smaller than 1.5mm, so that the ultrasonic welding marks 2 are not dropped on the staggered floor, the ultrasonic welding marks OK and the 180-degree peeling force test OK between the lugs 11 are ensured.

It should be noted that the tabs are not perfectly aligned, so "staggered layers" may be formed at the edge positions of the tabs.

The 180 ° peel force test between the tabs means that, for the tabs after ultrasonic welding, half of the tabs are folded 180 ° and peeled, and the peel force when half of the tabs are peeled from the other half of the tabs is tested, and the peel force is not less than 70N, which is the test qualification.

It should be further noted that the area ratio of the tab remained on the cover plate after the 180 ° peel force test was completed is not less than 80%.

In one embodiment, as shown in fig. 1, the width e of the ultrasonic welding 2 is 4mm to 20mm in the height direction of the tab 11. The electrode lug 11 is prevented from being torn while the laser welding is performed with enough width, and the safety of the battery cell is ensured.

It should be noted that, referring to fig. 1, the width of the ultrasonic welding mark 2 is e, and the width of e is 4mm less than or equal to 20mm.

It should be further noted that, if the width of the ultrasonic welding mark 2 is too small, it is inconvenient to perform laser welding at the position of the ultrasonic welding mark 2 in the subsequent step, and the welding strength between the tab 11 and the cover plate 4 cannot be ensured; if the width of the ultrasonic welding 2 is too large, uneven stress of the tab 11 is easily caused, so that the tab 11 is torn, and the service life of the ultrasonic welding head is reduced.

In one embodiment, as shown in fig. 2, the effective penetration f at the welded connection of the tab 11 and the cap plate 4 is 50 μm to 900 μm.

It should be noted that, referring to fig. 2, the effective penetration of the welding junction between the tab 11 and the cover plate 4 is f, which satisfies 50 μm and less than or equal to f and less than or equal to 900 μm.

In one embodiment, as shown in fig. 2, the effective welding width g of the welding joint of the tab 11 and the cover plate 4 is at least 1.5mm.

It should be noted that, referring to fig. 2, the effective melting width of the welding joint of the tab 11 and the cover plate 4 is g, which satisfies g being greater than or equal to 1.5mm.

The effective penetration and the effective width of the welding joint between the tab 11 and the cover plate 4 are limited, so that the connection strength between the tab 11 and the cover plate 4 is ensured.

It should be further noted that, referring to fig. 2, the effective penetration refers to the depth of welding from the joint surface of the tab 11 and the cover plate 4 to the inside of the cover plate 4, and the effective penetration refers to the width of welding at the joint surface of the tab 11 and the cover plate 4.

In one embodiment, as shown in fig. 2, the battery unit further includes an end plate 5, the end plate 5 is disposed between the end surface of the pole group 1 and the cover plate 4, the end plate 5 is provided with a through groove 51, the end plate 5 is further provided with a guiding surface 52, the tab 11 penetrates through the through groove 51 and is bent to be close to or fit with the guiding surface 52, and the tab 11 is bent for multiple times and then is fit with the cover plate 4 and is welded with the cover plate 4 by laser.

In one embodiment, the cover plate 4 has a width of 13mm to 40mm and the cover plate 4 has a length of 80mm to 300mm.

In one embodiment, the length of the battery cell is 300mm to 1200mm.

According to an embodiment of the present invention, in another aspect, there is also provided a battery pack including the above-described battery cell.

Although embodiments of the present invention have been described in connection with the accompanying drawings, various modifications and variations may be made by those skilled in the art without departing from the spirit and scope of the invention, and such modifications and variations fall within the scope of the invention as defined by the appended claims.

Claims

1. A battery cell, comprising:

A housing having an opening and being hollow inside;

The cover plate is arranged corresponding to the opening and connected with the shell so as to form an accommodating space in a surrounding way;

The electrode group is arranged in the accommodating space and comprises an electrode lug, ultrasonic welding marks are arranged on the electrode lug to be connected with the electrode lug which is arranged in a layered mode, the electrode lug and the cover plate are welded through laser to form laser welding marks on the electrode lug, and the laser welding marks are positioned in the ultrasonic welding marks;

The distances from the edge of the laser welding mark to the corresponding edge of the ultrasonic welding mark are a, b, c, d respectively, so that a is more than or equal to 0.5mm, b is more than or equal to 0.5mm, c is more than or equal to 0.5mm, and d is more than or equal to 0.5mm.

2. The battery cell according to claim 1, wherein along the length direction of the tab, the minimum distances from the edge of the ultrasonic welding to the edge of the corresponding tab are i and j, respectively, so that i is not less than 1.5mm and j is not less than 1.5mm.

3. The battery cell according to claim 1 or 2, wherein the width e of the ultrasonic welding is 4mm to 20mm in the height direction of the tab.

4. The battery cell according to claim 1 or 2, wherein the effective penetration f of the welded connection of the tab and the cap plate is 50 μm to 900 μm.

5. The battery cell of claim 1 or 2, wherein the effective melt width g of the welded connection of the tab and the cover plate is at least 1.5mm.

6. The battery cell according to claim 1 or 2, further comprising an end plate disposed between the end face of the pole group and the cover plate, wherein a through groove is formed in the end plate, a guide surface is further formed on the end plate, and the tab is bent to be close to or fit with the guide surface after penetrating through the through groove, and is fit with the cover plate after being bent for a plurality of times.

7. The battery cell according to claim 1 or 2, wherein the cover plate has a width of 13mm to 40mm and a length of 80mm to 300mm.

8. The battery cell of claim 1 or 2, wherein the battery cell has a length of 300mm to 1200mm.

9. A battery pack comprising the battery cell according to any one of claims 1 to 8.