Battery Pack

Abstract

The present disclosure relates to the field of battery technology, and discloses a battery pack; the battery pack may include a battery cell, a bus bar, and at least two first welding connections; the battery cell includes a battery shell; the material of the bus bar is different from that of the battery shell, and the melting point of the bus bar is lower than that of the battery shell; at least two first welding connections are connected between the bus bar and the battery shell, and the spacing between two adjacent first welding connections is greater than or equal to 4mm and less than or equal to 45mm. The battery pack connects the bus bar and the battery shell through at least two first welding connections, which can reduce the welding time required to form a first welding connection, so that the energy brought by the welding can be dispersed to a certain extent to prevent the occurrence of poor welding penetration; and the connection strength and flow area between the bus bar and the battery shell can be guaranteed.

Description

Technical Field

[0001] The present disclosure relates to the field of battery technology, and in particular, to a battery pack. Background Art

[0002] Multiple battery cells in a battery pack need to be connected through a busbar to achieve series and parallel connection of multiple battery cells. However, since the battery case is made of steel and the busbar is made of aluminum, the melting points of steel and aluminum are different, which leads to insufficient welding strength or poor welding when welding the battery case and the busbar, thus affecting the electrical performance of the battery pack.

[0003] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0004] The purpose of the present disclosure is to overcome the deficiencies of the above-mentioned related technologies and provide a battery pack.

[0005] According to one aspect of the present disclosure, there is provided a battery pack, comprising:

[0006] A battery cell, including a battery housing;

[0007] A busbar, wherein the material of the busbar is different from the material of the battery shell, and the melting point of the busbar is lower than the melting point of the battery shell;

[0008] At least two first welding connection parts are connected between the busbar and the battery housing, and a distance between two adjacent first welding connection parts is greater than or equal to 4 mm and less than or equal to 45 mm.

[0009] The battery pack disclosed in the present invention, on the one hand, has a high strength of the first welding connection portion, and the bus bar and the battery shell will not be separated, so as to ensure the electrical connection effect between the bus bar and the battery shell, thereby ensuring the electrical performance of the battery pack; on the other hand, the bus bar and the battery shell are connected by at least two first welding connections, which can reduce the welding time required to form a first welding connection, so that the energy brought by the welding can be dispersed to a certain extent to prevent the defect of welding through; moreover, the connection strength and flow area between the bus bar and the battery shell can be guaranteed; on the other hand, the spacing between two adjacent first welding connections is greater than or equal to 4mm and less than or equal to 45mm, which not only ensures that when another first welding connection is formed by welding, it will not affect the first welding connection that has been formed; but also ensures that a first welding connection with a sufficiently large area can be set on the bus to ensure the strength and flow area of ​​the first welding connection.

[0010] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0012] Figure 1 It is a schematic structural diagram of an exemplary embodiment of the battery pack disclosed herein.

[0013] Figure 2 for Figure 1 Schematic diagram of the three-dimensional structure of a medium cylindrical battery.

[0014] Figure 3 for Figure 1 A simplified schematic diagram of the structure of the first welding connection part.

[0015] Description of reference numerals:

[0016] 1. Battery box; 11. First side frame; 12. Second side frame; 13. Bottom plate;

[0017] 2. Battery array; 21. Battery cell; 21a. First battery cell; 21b. Second battery cell; 211. Battery housing; 2111. Cover plate; 2112. Side wall; 2113. Bottom wall; 212. Battery pole; 213. Insulator;

[0018] 3. Busbar; 31. Step structure;

[0019] 4. first welding connection portion; 41. arc connection portion;

[0020] 5. Insulating plate; 6. Second welding connection portion; 7. Third welding connection portion;

[0021] X, first direction; Y, second direction. DETAILED DESCRIPTION

[0022] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure will be comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their detailed description will be omitted. In addition, the drawings are only schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0023] Although relative terms such as "upper" and "lower" are used in this specification to describe the relative relationship of one component of the illustration to another component, these terms are used in this specification only for convenience, such as according to the orientation of the examples described in the drawings. It is understood that if the device of the illustration is turned upside down, the component described as "upper" will become the component "lower". When a structure is "on" other structures, it may mean that the structure is formed integrally on the other structure, or that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure through another structure.

[0024] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express an open-ended inclusive meaning and mean that additional elements / components / etc. may exist in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used merely as labels and are not intended to limit the quantity of their objects.

[0025] In this application, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium. "And / or" is just a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the previous and next associated objects are in an "or" relationship.

[0026] The exemplary embodiment of the present disclosure provides a battery pack, referring to Figure 1-Figure 3 As shown, the battery pack may include a battery cell 21, a bus 3 and at least two first welding connections 4; the battery cell 21 may include a battery shell 211; the material of the bus 3 is different from that of the battery shell 211, and the melting point of the bus 3 is lower than the melting point of the battery shell 211; at least two first welding connections 4 are connected between the bus 3 and the battery shell 211, and the spacing between two adjacent first welding connections 4 is greater than or equal to 4mm and less than or equal to 45mm.

[0027] In the battery pack disclosed in the present invention, on the one hand, the first welding connection part 4 has high strength, and the bus bar 3 and the battery shell 211 will not be separated, so as to ensure the electrical connection effect between the bus bar 3 and the battery shell 211, thereby ensuring the electrical performance of the battery pack; on the other hand, by connecting the bus bar 3 and the battery shell 211 through at least two first welding connections 4, the welding time required to form a first welding connection part 4 can be reduced, so that the energy brought by the welding can be dispersed to a certain extent to prevent the defect of welding through; moreover, the connection strength and flow area between the bus bar 3 and the battery shell 211 can be ensured; on the other hand, the spacing between two adjacent first welding connections 4 is greater than or equal to 4mm and less than or equal to 45mm, which not only ensures that when another first welding connection part 4 is formed by welding, it will not affect the first welding connection part 4 that has been formed; but also ensures that a first welding connection part 4 with a sufficiently large area can be set on the bus bar 3 to ensure the strength and flow area of ​​the first welding connection part 4.

[0028] In this example implementation, refer to Figure 1 As shown, the battery pack may include a battery case 1, and the battery case 1 may be set to a rectangular parallelepiped structure. Specifically, the battery case 1 may include a bottom plate 13, a protective cover, two first side frames 11 and two second side frames 12, and the bottom plate 13 and the protective cover may be set to a rectangular shape. Two first side frames 11 and two second side frames 12 are arranged around the bottom plate 13, and the two first side frames 11 and the two second side frames 12 are connected end to end to form a rectangular frame, the first side frame 11 extends along the first direction X, and the second side frame 12 extends along the second direction Y. A protective cover is arranged on the other side of the two first side frames 11 and the two second side frames 12 opposite to the bottom plate 13, so that the protective cover is arranged opposite to the bottom plate 13, and the two first side frames 11 and the two second side frames 12 are connected between the protective cover and the bottom plate 13. The bottom plate 13, the protective cover, the two first side frames 11 and the two second side frames 12 surround and form a accommodating cavity of the battery case 1.

[0029] It should be noted that both the first direction X and the second direction Y are parallel to the bottom plate 13 , and the first direction X intersects with the second direction Y. For example, the first direction X is perpendicular to the second direction Y.

[0030] Of course, in some other exemplary embodiments of the present disclosure, the bottom plate 13 and the protective cover can be set to be circular, elliptical, trapezoidal, etc., and the side frame can be set to one or more, and surrounded to form a circular, elliptical, trapezoidal, etc., so that the battery box 1 is formed into a cylindrical, elliptical column, prism, etc. The battery box 1 can also be other shapes, which are not described here one by one.

[0031] Reference Figure 1As shown, a battery column 2 is arranged in the battery box 1. A battery column 2 may include at least two battery cells 21 arranged in sequence along a first direction X. For example, two battery cells 21 may be arranged in sequence along the first direction X to form a battery column 2, or three or more battery cells 21 may be arranged in sequence along the first direction X to form a battery column 2. Multiple battery cells 21 are arranged to form multiple battery columns 2.

[0032] The battery cells 21 in two adjacent battery columns 2 are staggered. For example, the gaps between the battery cells 21 in the first column and the adjacent two battery cells 21 in the second column are arranged opposite to each other, rather than the battery cells 21 in the first column and the battery cells 21 in the second column being arranged opposite to each other, so as to improve the space utilization of the accommodating cavity of the battery box 1, thereby improving the energy density of the battery device.

[0033] In this example implementation, refer to Figure 1 and Figure 2 As shown, the battery cell 21 can be a cylindrical battery, and the battery housing 211 can be set as a cylinder, that is, the battery housing 211 can include a cover plate 2111 and a bottom wall 2113 that are arranged opposite to each other, and the cover plate 2111 and the bottom wall 2113 are both arranged in a circular shape, and a side wall 2112 is connected between the cover plate 2111 and the bottom wall 2113, and the side wall 2112 is arranged in a cylindrical shape. The side wall 2112, the cover plate 2111 and the bottom wall 2113 surround and form a receiving cavity for the battery cell 21. The outer surface of the side wall 2112 is the side surface of the battery cell 21, and the side surface is cylindrical; the outer surfaces of the cover plate 2111 and the bottom wall 2113 are the end surfaces of the battery cell 21, and the end surfaces are circular planes or annular planes; so that the side surface and the end surface are arranged to intersect, for example, the side surface and the end surface can be arranged vertically.

[0034] Moreover, a third welding connection portion 7 is connected between the cover plate 2111 and the side wall 2112 , and the third welding connection portion 7 is arranged to form a circle surrounding the edge of the cover plate 2111 .

[0035] Of course, in some other example embodiments of the present disclosure, the battery cell 21 may also be a quadrangular prism battery, a pentagonal prism battery, a hexagonal prism battery, etc. In this case, the side surface may include multiple rectangular planar sub-side surfaces, and the end surface may be set as a rectangular, pentagonal, hexagonal, etc. plane.

[0036] In this example embodiment, a battery cell is arranged in the accommodating cavity of the battery housing 211, and the battery cell may include a battery cell body, a first pole ear and a second pole ear, and the polarity of the first pole ear is opposite to that of the second pole ear. The battery cell body is arranged as a column, for example, the battery cell body can be arranged as a cylinder adapted to the battery housing 211. The battery cell body has a first end face and a second end face, and the first end face is arranged opposite to the second end face. The battery cell body may include a first pole piece and a second pole piece, and a separation film arranged between the first pole piece and the second pole piece, and the battery cell body may be formed by winding the first pole piece, the separation film and the second pole piece arranged in a stacked manner. Active material is coated on the first pole piece and the second pole piece.

[0037] The first pole ear is connected to the battery cell body, specifically, the first pole ear is connected to the first pole piece; the first pole ear is located at the first end surface of the battery cell body close to the cover plate 2111. The second pole ear is connected to the battery cell body, specifically, the second pole ear is connected to the second pole piece; and the second pole ear can be located on the same side of the battery cell body as the first pole ear, that is, the second pole ear can be located at the first end surface of the battery cell body close to the cover plate 2111, so that the first pole ear and the second pole ear are arranged on the side of the first end surface away from the battery cell body.

[0038] The first pole tab may be a portion of the multi-layer first pole sheet extending out of the battery body, and being bent to the side of the first end face of the battery body away from the battery body to form the first pole tab, so that the first pole tab may include a multi-layer first pole tab sheet. The second pole tab may be a portion of the multi-layer second pole sheet extending out of the battery body, and being bent to the side of the first end face of the battery body away from the battery body to form the second pole tab, so that the second pole tab may include a multi-layer second pole tab sheet.

[0039] It should be noted that the first pole tab and the second pole tab are conductive foil areas without active material coating, that is, no active material coating is coated on the first pole tab and the second pole tab, and the first pole tab and the second pole tab are current collecting layers for transmitting current.

[0040] In this example implementation, refer to Figure 2 As shown, the battery column 212 is insulated and connected to the battery housing 211. For example, the battery column 212 is insulated and connected to the cover plate 2111. Specifically, a through hole is provided on the cover plate 2111, and the battery column 212 passes through the through hole and is riveted to the cover plate 2111. An insulating member 213 is provided between the battery column 212 and the cover plate 2111 to insulate the battery column 212 from the cover plate 2111.

[0041] The battery pole 212 is connected to the first pole ear, and the battery pole 212 is the first electrode of the battery cell 21, and the first electrode can be a positive electrode; the cover plate 2111 is connected to the second pole ear, and the cover plate 2111 is the second electrode of the battery cell 21, and the second electrode can be a negative electrode; so that the first electrode and the second electrode are arranged at the same end of the battery cell 21. Of course, the first electrode can also be a negative electrode and the second electrode can be a positive electrode. Such an arrangement enables the battery cells 21 to be connected in series or in parallel at one end of the battery cell 21, which facilitates the electrical connection between the battery cells 21.

[0042] In this example implementation, refer to Figure 1 As shown, the battery device may further include a bus 3, the bus 3 is connected to the end surface of the battery cell 21, specifically, the bus 3 is connected to two adjacent battery cells 21 arranged in sequence along the first direction X, the two adjacent battery cells 21 are the first battery cell 21a and the second battery cell 21b, the bus 3 is connected to the battery shell 211 of the first battery cell 21a through at least two first welding connections 4, specifically, the bus 3 is connected to the cover plate 2111 of the first battery cell 21a through at least two first welding connections 4; the bus 3 is connected to the battery pole 212 of the second battery cell 21b through the second welding connection 6, so that the two adjacent battery cells 21 arranged in sequence along the first direction X are connected in series, therefore, the bus 3 realizes the electrical connection of the battery cells 21, and the bus 3 needs to conduct current.

[0043] The second welding connection portion 6 is configured as a continuous structure, that is, the second welding connection portion 6 is configured as one and is configured as a structure connected as an integral whole. For example, the second welding connection portion 6 can be configured as a ring shape; moreover, the second welding connection portion 6 is adapted to the battery pole 212. For example, if the battery pole 212 is configured as a cylinder, the second welding connection portion 6 can be configured as a ring; if the battery pole 212 is configured as various polygonal prisms, the second welding connection portion 6 can be configured as various polygonal ring shapes.

[0044] The material of the battery pole is the same as that of the busbar 3 , so that the strength of the second welding connection portion 6 between the battery pole 212 and the busbar 3 is relatively large, thereby ensuring the welding strength between the battery pole 212 and the busbar 3 .

[0045] The busbar 3 is provided with a step structure 31, which is located between the first welding connection part 4 and the second welding connection part 6, and is closer to the first welding connection part. Specifically, since the battery pole 212 protrudes from the cover plate 2111 of the battery housing 211, the busbar 3 may include a first part, a second part and a third part connected in sequence, the first part is connected to the battery pole 212, the third part is connected to the cover plate 2111, the height of the first part is higher than the third part, and the second part is substantially perpendicular to the first part and the third part to form the step structure 31.

[0046] The edge of the welding connection is a stress concentration point. The more welding connections there are, the more stress concentration points there are. During the welding process, the connection strength is not high. Setting a step structure 31 near the first welding connection 4 can buffer the stress concentration area and ensure the connection strength.

[0047] The spacing between the third welding connection part 7 and the first welding connection part 4 is greater than or equal to 6 mm. For example, the spacing between the third welding connection part 7 and the first welding connection part 4 can be 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, 10.5 mm, 11 mm, etc. Avoid mutual influence between the third welding connection part 7 and the first welding connection part 4.

[0048] Moreover, refer to Figure 1 As shown, an insulating plate 5 is arranged between the bus 3 and the battery cell 21, and a through hole is arranged on the insulating plate 5, so that the battery pole 212 and a part of the cover plate 2111 of the battery cell are exposed, so as to facilitate the connection between the bus 3 and the battery pole 212 and the cover plate 2111; the bus 3 is connected to the battery pole 212 of a battery cell 21, and it is necessary to insulate the cover plate 2111 of the battery cell 21 through the insulating plate 5. Similarly, the bus 3 is connected to the cover plate 2111 of a battery cell 21, and it is necessary to insulate the battery pole 212 of the battery cell 21 to avoid short circuit between the positive and negative electrodes of the same battery cell 21.

[0049] In this example implementation, refer to Figure 1 As shown, at least two first welding connections 4 are connected between the busbar 3 and the battery housing 211. Specifically, the first welding connection 4 can be a laser welding connection, that is, the first welding connection 4 is formed by laser welding. Of course, the first welding connection 4 can also be formed by other welding processes, which will not be described here one by one.

[0050] In the prior art, the strength of the brazing connection formed by brazing is relatively low. During the use of the battery pack, the bus bar 3 is prone to detachment from the battery shell 211, affecting the electrical connection between the bus bar 3 and the battery shell 211. Compared with the brazing connection, the first welding connection 4 has a higher strength and will not detach from the bus bar 3 and the battery shell 211, thereby ensuring the electrical connection between the bus bar 3 and the battery shell 211 and thus ensuring the electrical performance of the battery pack.

[0051] However, since the material of the bus 3 is different from that of the battery shell 211, the melting point of the battery shell 211 is quite different from that of the bus 3. If the energy used in laser welding is high, the local temperature will be too high and there is a risk of welding through. If the energy used in laser welding is low, the strength of the first welding connection 4 will be low. During the use of the battery pack, the bus 3 and the battery shell 211 may easily detach, affecting the electrical connection between the bus 3 and the battery shell 211.

[0052] By connecting the bus 3 and the battery shell 211 through at least two first welding connections 4, the time required for laser welding to form a first welding connection 4 can be reduced, so that the energy brought by the laser welding can be dispersed to a certain extent to prevent the occurrence of welding defects; moreover, the connection strength and flow area between the bus 3 and the battery shell 211 can be guaranteed.

[0053] The spacing between two adjacent first welding connections 4 is greater than or equal to 2 mm and less than or equal to 45 mm. For example, the spacing between two adjacent first welding connections 4 can be 5 mm, 7 mm, 10 mm, 13 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm, 27 mm, 30 mm, 33 mm, 35 mm, 38 mm, 40 mm, 42 mm, etc.

[0054] If the spacing between two adjacent first welding connections 4 is too small, when another first welding connection 4 is formed by welding, the already formed first welding connection 4 will be affected. For example, the heat generated by the laser will be transferred to the already formed first welding connection 4, causing the first welding connection 4 to produce a defective weld through.

[0055] If the interval between two adjacent first welding connections 4 is too large, it will result in that a first welding connection 4 with a sufficiently large area cannot be provided on the busbar 3 , thereby affecting the strength and flow area of ​​the first welding connection 4 .

[0056] The above numerical range not only ensures that when another first welding connection 4 is formed by welding, the already formed first welding connection 4 will not be affected; it also ensures that a first welding connection 4 with a sufficiently large area can be provided on the bus 3 to ensure the strength and flow area of ​​the first welding connection 4.

[0057] Optionally, the melting point of the busbar 3 may be lower than that of the battery case 211 , that is, the melting point of the battery case 211 is higher, which is beneficial to the high temperature resistance of the battery case 211 , thereby being beneficial to the high temperature resistance of the battery cell 21 , thereby increasing the safety of the battery cell 21 .

[0058] In this case, the spacing between two adjacent first welding connections 4 is greater than or equal to 4 mm and less than or equal to 45 mm; since the melting point of the bus 3 is low, if the spacing between two adjacent first welding connections 4 can be set smaller, when another first welding connection 4 is formed by welding, it will affect the already formed first welding connection 4; therefore, setting the spacing between two adjacent first welding connections 4 larger can avoid poor welding at the bus 3.

[0059] Moreover, the thickness of the busbar 3 is greater than the thickness of the battery shell 211; since the melting point of the busbar 3 is relatively low, if the thickness of the busbar 3 is relatively thin, the busbar 3 can be easily penetrated by welding, resulting in poor welding and affecting the welding strength; the thickness of the busbar 3 is set to be thicker, so that the busbar 3 is not easily penetrated by welding, thereby ensuring the welding strength.

[0060] In this exemplary embodiment, the material of the battery housing 211 may include steel, for example, the material of the battery housing 211 may be steel or a steel alloy; the material of the busbar 3 may include aluminum, for example, the material of the busbar 3 may be aluminum or an aluminum alloy. This can ensure both the conductivity of the battery housing 211 and the busbar 3 and the strength of the battery housing 211; and the material of aluminum or aluminum alloy is relatively soft, so that the busbar 3 can absorb the vibration transmitted by the battery cell 21 and provide a buffering effect to ensure the connection stability between the busbar 3 and two adjacent battery cells 21.

[0061] Of course, in some other example embodiments of the present disclosure, the melting point of the busbar 3 may be greater than the melting point of the battery housing 211 , so that the melting point of the busbar 3 is higher and more resistant to high temperatures to ensure the current flow capacity of the busbar 3 .

[0062] In this case, the spacing between two adjacent first welding connections 4 is greater than or equal to 2 mm and less than or equal to 42 mm. Since the bus 3 has a high melting point, the spacing between two adjacent first welding connections 4 can be set smaller. When another first welding connection 4 is formed by welding, it will not affect the already formed first welding connection 4, thereby improving the current carrying capacity.

[0063] Moreover, the thickness of the busbar 3 is greater than the thickness of the battery housing 211 ; since the busbar 3 has a relatively high melting point, the busbar 3 is set thicker to ensure the strength of welding.

[0064] At least a portion of the first welded connection portion 4 is arranged as a curve. For example, a portion of the first welded connection portion 4 may be arranged as a curve, or the entire first welded connection portion 4 may be arranged as a curve.

[0065] Alternatively, refer to Figure 3 As shown, the first welding connection part 4 can be set in a spiral shape, so that the first welding connection part 4 can include a plurality of circles of arc-shaped connection parts 41 connected in sequence. Moreover, the penetration depth and penetration width of each part of the first welding connection part 4 are substantially the same.

[0066] It should be noted that the spiral first welding connection portion 4 means that the first welding connection portion 4 can be a two-dimensional spiral line in each cross section parallel to the cover plate 2111 .

[0067] During laser welding, the laser welding head moves along the trajectory of a two-dimensional spiral line, thereby preventing the laser welding head from staying in the same position and causing the temperature of that position to rise too high, thus avoiding welding defects; and the use of spiral welding can increase the welding interface, that is, increase the connection interface between the bus 3 and the battery shell 211, thereby improving the connection strength between the bus 3 and the battery shell 211.

[0068] Specifically, the first welding connection part 4 can be set to be circular, and the diameter of the first welding connection part 4 is greater than or equal to 4 mm and less than or equal to 8 mm. For example, the diameter of the first welding connection part 4 can be 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, etc.

[0069] If the diameter of the first welding connection 4 is too small, the area of ​​the first welding connection 4 is too small, resulting in a weak connection strength between the bus 3 and the battery shell 211. During the use of the battery pack, the bus 3 and the battery shell 211 are easily separated. In addition, the flow area between the bus 3 and the battery shell 211 is small, which affects the electrical performance of the battery pack.

[0070] If the diameter of the first welding connection part 4 is too large, the area of ​​the first welding connection part 4 is too large, which may easily exceed the bus bar 3 and be too close to the battery pole 212 , thereby causing a short circuit on the surface of the battery shell 211 .

[0071] The above-mentioned numerical range not only ensures sufficient connection strength between the bus bar 3 and the battery shell 211, and prevents the bus bar 3 from being separated from the battery shell 211 during use of the battery pack, but also ensures the flow area between the bus bar 3 and the battery shell 211; and ensures that the first welding connection 4 does not extend beyond the bus bar 3, and a short circuit on the surface of the battery shell 211 does not occur.

[0072] It should be noted that the diameter of the first welding connection portion 4 may be the diameter of the largest circumscribed circle of the first welding connection portion 4, such as Figure 3 Shown by the dashed line.

[0073] In this example embodiment, the distance K between two adjacent arc-shaped connecting portions 41 is greater than or equal to 0.05 mm and less than or equal to 0.3 mm. For example, the distance K between two adjacent arc-shaped connecting portions 41 can be 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.17 mm, 0.2 mm, 0.23 mm, 0.25 mm, 0.28 mm, etc.

[0074] If the distance K between two adjacent circles of arc-shaped connection parts 41 is too large, the number of circles that can be formed in the first welding connection part 4 within the same area will be small, resulting in a weak connection strength between the bus 3 and the battery shell 211. During the use of the battery pack, the bus 3 and the battery shell 211 are prone to separation. Moreover, the flow area between the bus 3 and the battery shell 211 is small, which affects the electrical performance of the battery pack.

[0075] If the distance K between two adjacent circles of arc-shaped connecting parts 41 is too small, when another circle of arc-shaped connecting parts 41 is formed by welding, it will affect the already formed arc-shaped connecting parts 41. For example, the heat generated by the laser will be transferred to the already formed arc-shaped connecting parts 41, causing the arc-shaped connecting parts 41 to have a poor weld-through.

[0076] The above-mentioned numerical range not only ensures that the number of circles that can be formed in the first welding connection part 4 within the same area can ensure the connection strength between the bus bar 3 and the battery shell 211, and does not cause the bus bar 3 to be separated from the battery shell 211 during the use of the battery pack, but also ensures the flow area between the bus bar 3 and the battery shell 211; and also ensures that when another arc-shaped connection part 41 is formed by welding, the arc-shaped connection part 41 that has already been formed will not be affected.

[0077] It should be noted that the distance K between two adjacent circles of arc-shaped connecting portions 41 may be the distance between the edges of the two adjacent circles of arc-shaped connecting portions 41 that are close to each other.

[0078] In some example embodiments of the present disclosure, the penetration depth of the first weld connection 4 is greater than or equal to 0.2 mm and less than or equal to 0.4 mm. For example, the penetration depth of the first weld connection 4 may be 0.23 mm, 0.25 mm, 0.28 mm, 0.3 mm, 0.32 mm, 0.35 mm, 0.37 mm, etc.

[0079] If the penetration of the first welded connection portion 4 is too great, the welding time required will be too long, which may easily lead to weld penetration.

[0080] If the penetration depth of the first welding connection portion 4 is too small, the connection strength between the busbar 3 and the battery case 211 is weak, and the busbar 3 is easily separated from the battery case 211 during use of the battery pack.

[0081] The above numerical range not only ensures that the connection strength between the busbar 3 and the battery housing 211 is sufficient, and the busbar 3 will not be separated from the battery housing 211 during the use of the battery pack; but also prevents welding failure.

[0082] The weld width of the first weld connection portion 4 is greater than or equal to 2 mm and less than or equal to 4 mm. For example, the weld width of the first weld connection portion 4 may be 2.3 mm, 2.5 mm, 2.8 mm, 3 mm, 3.2 mm, 3.5 mm, 3.7 mm, and the like.

[0083] If the weld width of the first welded connection portion 4 is too large, the welding time required will be too long, which may easily lead to weld penetration.

[0084] If the weld width of the first welding connection portion 4 is too small, the connection strength between the busbar 3 and the battery case 211 is weak, and the busbar 3 is easily separated from the battery case 211 during use of the battery pack.

[0085] The above numerical range not only ensures that the connection strength between the busbar 3 and the battery housing 211 is sufficient, and the busbar 3 will not be separated from the battery housing 211 during the use of the battery pack; but also prevents welding failure.

[0086] It should be noted that the depth of penetration of the first welding connection part 4 is basically proportional to the weld width of the first welding connection part 4; that is, generally, the greater the depth of penetration of the first welding connection part 4, the greater the weld width of the first welding connection part 4; the smaller the depth of penetration of the first welding connection part 4, the smaller the weld width of the first welding connection part 4.

[0087] In some example embodiments of the present disclosure, the spacing between two adjacent first welding connections 4 is greater than or equal to 5 mm and less than or equal to 40 mm, and the ratio of the thickness of the busbar 3 to the wall thickness of the battery case 211 is greater than or equal to 1.4 and less than or equal to 3.4. Specifically, the ratio of the thickness of the busbar 3 to the thickness of the cover plate 2111 is greater than or equal to 1.4 and less than or equal to 3.4. For example, the ratio of the thickness of the busbar 3 to the wall thickness of the battery case 211 can be 1.7, 2, 2.3, 2.5, 2.8, 3, 3.2, and so on.

[0088] If the ratio of the thickness of the busbar 3 to the wall thickness of the battery housing 211 is too small, there is a risk that the busbar 3 may be welded through.

[0089] If the ratio of the thickness of the busbar 3 to the wall thickness of the battery shell 211 is too large, it is easy for the battery shell 211 to not melt even after a long welding time, resulting in a weak connection strength between the busbar 3 and the battery shell 211. During the use of the battery pack, the busbar 3 and the battery shell 211 may easily separate.

[0090] The above numerical range not only reduces the risk of the busbar 3 being welded through, but also ensures that the connection strength between the busbar 3 and the battery shell 211 is sufficient, so that the busbar 3 will not be separated from the battery shell 211 during the use of the battery pack.

[0091] In some example embodiments of the present disclosure, the area of ​​the overlapping portion of the busbar 3 and the battery housing 211 is the first area, the ratio of the area of ​​the first welding connection 4 to the first area is greater than or equal to 0.06 and less than or equal to 0.13, and the ratio of the area of ​​the first welding connection 4 to the first area can be 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, etc.

[0092] Generally, after the design of the battery cell 21 is completed, the first area is already a fixed value; if the ratio of the area of ​​the first welding connection part 4 to the first area is too small, the area of ​​the first welding connection part 4 is too small, resulting in a weak connection strength between the bus 3 and the battery shell 211. During the use of the battery pack, the bus 3 is prone to detachment from the battery shell 211.

[0093] If the ratio of the area of ​​the first welding connection 4 to the first area is too large, so that the spacing between two adjacent first welding connection parts 4 is too small, when another first welding connection part 4 is formed by laser welding, it will affect the already formed first welding connection part 4. For example, the heat generated by the laser will be transferred to the already formed first welding connection part 4, causing the first welding connection part 4 to produce a defective weld through.

[0094] The above numerical range not only ensures that the area of ​​the first welding connection 4 is sufficient to ensure sufficient connection strength between the bus 3 and the battery shell 211, and prevents the bus 3 from being separated from the battery shell 211 during the use of the battery pack; but also ensures that when another first welding connection 4 is formed by laser welding, it will not affect the first welding connection 4 that has already been formed.

[0095] In this example embodiment, two first welding connection parts 4 may be provided. Since the overlapping area of ​​the busbar 3 and the battery housing 211 is small, if more first welding connection parts 4 are provided, the area of ​​one first welding connection part 4 will be too small, and the connection strength between the busbar 3 and the battery housing 211 cannot be guaranteed. During the use of the battery pack, the busbar 3 and the battery housing 211 may be easily separated.

[0096] Of course, in some other exemplary embodiments of the present disclosure, three or more first welding connection parts 4 may be provided.

[0097] In this example embodiment, the distance between the battery pole 212 and the first welding connection 4 is greater than or equal to 4 mm and less than or equal to 42 mm. For example, the distance between the battery pole 212 and the first welding connection 4 can be 7 mm, 10 mm, 13 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm, 27 mm, 30 mm, 33 mm, 35 mm, 38 mm, 40 mm, etc.

[0098] If the distance between the battery post 212 and the first welding connection part 4 is too small, heat will be transferred to the battery post 212 during the welding process, affecting the insulating part 213 between the battery post 212 and the battery shell 211, which may easily lead to insulation failure, resulting in the distance between the bus 3 and the battery post 212 being too small, causing a short circuit.

[0099] If the distance between the battery pole 212 and the first welding connection part 4 is too large and insufficient to accommodate the first welding connection part 4 with a sufficient area, the connection strength between the bus bar 3 and the battery shell 211 cannot be guaranteed. During the use of the battery pack, the bus bar 3 is prone to detachment from the battery shell 211.

[0100] The above numerical range not only ensures that the insulating part 213 between the battery pole 212 and the battery shell 211 will not be affected during the welding process, and will not cause insulation failure; the distance between the bus 3 and the battery pole 212 is relatively appropriate to avoid a short circuit between the bus 3 and the battery pole 212; and it can accommodate a first welding connection part 4 of sufficient area to ensure the connection strength between the bus 3 and the battery shell 211, and during the use of the battery pack, the bus 3 will not be separated from the battery shell 211.

[0101] The "parallel" and "perpendicular" mentioned in this application can not only be completely parallel or perpendicular, but also can have a certain error; for example, if the angle between the two is greater than or equal to 0° and less than or equal to 5°, the two are considered to be parallel to each other; if the angle between the two is greater than or equal to 85° and less than or equal to 95°, the two are considered to be perpendicular to each other.

[0102] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary techniques in the art that are not disclosed in the present disclosure. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present disclosure are indicated by the appended claims.

Claims

1. A battery pack, characterized in that: include: A battery cell, including a battery housing; A busbar, wherein the material of the busbar is different from the material of the battery shell, and the melting point of the busbar is lower than the melting point of the battery shell; At least two first welding connections are connected between the busbar and the battery housing, the spacing between two adjacent first welding connections is greater than or equal to 4 mm and less than or equal to 45 mm, and the first welding connection is a weld mark formed by welding.

2. The battery pack according to claim 1, characterized in that: The thickness of the busbar is greater than the thickness of the battery case.

3. The battery pack according to claim 1, characterized in that: The material of the battery housing includes steel, and the material of the busbar includes aluminum.

4. The battery pack according to claim 1, characterized in that: At least a portion of the first weld connection is configured as a curve.

5. The battery pack according to any one of claims 1 to 4, characterized in that: The area of ​​the overlapping portion of the busbar and the battery housing is a first area, and the ratio of the area of ​​the first welding connection portion to the first area is greater than or equal to 0.06 and less than or equal to 0.

13.

6. The battery pack according to any one of claims 1 to 4, characterized in that: The distance between two adjacent first welding connection parts is greater than or equal to 5 mm and less than or equal to 40 mm, and the ratio of the thickness of the busbar to the wall thickness of the battery housing is greater than or equal to 1.4 and less than or equal to 3.

4.

7. The battery pack according to any one of claims 1 to 4, characterized in that: The battery cell further comprises: A battery pole is insulated and connected to the battery shell, the battery pole and the bus are connected to the same end surface of the battery shell, and the distance between the battery pole and the first welding connection portion is greater than or equal to 4mm and less than or equal to 42mm.

8. The battery pack according to claim 7, characterized in that: The two adjacent battery cells are a first battery cell and a second battery cell, the bus is connected to the battery shell of the first battery cell through at least two of the first welding connections, the bus is connected to the battery pole of the second battery cell through a second welding connection, and the second welding connection is set as a continuous structure; the material of the battery pole is the same as that of the bus; a step structure is set on the bus, and the step structure is located between the first welding connection and the second welding connection, and is closer to the first welding connection.

9. The battery pack according to any one of claims 1 to 4, characterized in that: The battery housing includes a cover plate and a side wall, a third welding connection portion is connected between the cover plate and the side wall, the third welding connection portion is arranged as a circle around the edge of the cover plate, and the spacing between the third welding connection portion and the first welding connection portion is greater than or equal to 6 mm.

10. The battery pack according to any one of claims 1 to 4, characterized in that: The battery cell is a cylindrical battery.

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