Battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises an assembly main body and an anti-explosion valve. The assembling main body is provided with a mounting hole; the anti-explosion valve comprises an anti-explosion valve body, a flange edge arranged on the outer ring of the anti-explosion valve body and a transition edge connected with the anti-explosion valve body and the flange edge, and the flange edge and the transition edge protrude out of the plane where the anti-explosion valve body is located. The explosion-proof valve body is arranged in the mounting hole, and the flange edge is arranged on the first end face of the mounting hole and welded to the assembly body. According to the battery cell provided by the invention, the explosion-proof valve is provided with the flange edge, the flange edge protrudes out of the plane where the explosion-proof valve body is located, and the explosion-proof valve is welded with the assembly main body through the flange edge, so that compared with the mode that the explosion-proof valve body is directly welded with the assembly main body, the conduction path of welding heat can be effectively prolonged; the anti-explosion valve is prevented from being deformed and cracked due to welding heat, so that the anti-explosion valve can be opened under the designed pressure, and the safety of the battery cell and the battery pack is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to battery cells and battery packs. Background Art

[0002] In recent years, the global battery cell market has continued to expand and will continue to maintain a high growth trend. In terms of technology, the performance indicators of battery cells such as energy density, safety, and cycle life are constantly improving.

[0003] An important component in the battery cell is the explosion-proof valve, which not only prevents excessive internal pressure and thermal runaway, but also protects the electrolyte from leakage, ensuring the stability and safety of the battery cell.

[0004] The explosion-proof valve is fixed to the cover or shell of the battery cell by welding. However, during the welding process of the explosion-proof valve, due to the high welding heat, the heat is transferred to the explosion-proof valve, causing the explosion-proof valve to be easily deformed or even cracked due to the heat, thereby affecting the safety of the battery cell. Summary of the invention

[0005] In view of this, the present invention provides a battery cell and a battery pack to solve the problem that the explosion-proof valve is easily deformed and cracked due to the influence of welding heat.

[0006] In a first aspect, the present invention provides a battery cell, comprising an assembly body and an explosion-proof valve. The assembly body has a first end face along the X1 direction and a second end face along the X2 direction, and the assembly body is provided with a mounting hole penetrating the first end face and the second end face thereof; the explosion-proof valve comprises an explosion-proof valve body, a flange edge provided at the outer ring of the explosion-proof valve body, and a transition edge connecting the explosion-proof valve body and the flange edge, and the flange edge and the transition edge protrude from the plane where the explosion-proof valve body is located; the explosion-proof valve body is provided at the mounting hole, and the flange edge is provided at the first end face of the mounting hole along the X1 direction, and is welded to the assembly body.

[0007] Beneficial effect: The battery cell provided by the present invention has a transition edge and a flange edge provided on the explosion-proof valve, and the transition edge and the flange edge protrude from the plane where the explosion-proof valve body is located. The explosion-proof valve is welded to the assembly body through the flange edge. Compared with the direct welding of the explosion-proof valve body to the assembly body, the conduction path of the welding heat can be effectively extended, and the explosion-proof valve can be prevented from being deformed and cracked due to the welding heat, thereby ensuring that the explosion-proof valve can be opened under the design pressure and ensuring the safety of the battery cell and the battery pack.

[0008] In an optional embodiment, the mounting hole is a stepped hole including a first hole section and a second hole section, the inner diameter of the second hole section is larger than the inner diameter of the first hole section, the second hole section is close to the first end face of the assembly body, the explosion-proof valve body is arranged in the first hole section, and the flange edge is arranged in the second hole section.

[0009] In an optional implementation, the angle between the transition edge and the explosion-proof valve body is α, 90°≤α≤175°; the angle between the transition edge and the flange edge is β, which is vertical, 90°≤β≤175°.

[0010] In an optional embodiment, there is a gap between the transition edge and the inner wall of the first hole segment.

[0011] In an optional implementation, the width of the gap is W1, 0.3 mm ≤ W1 ≤ 10 mm.

[0012] In an optional embodiment, the flange edge is arranged at the bottom of the second hole segment, the flange edge and the first end surface of the second hole segment along the X1 direction are welded to each other, and the contact width between the flange edge and the bottom of the second hole segment is W2, 0.8mm≤W2≤4mm.

[0013] In an optional embodiment, the flange edge is arranged at the bottom of the second hole segment, and the two are penetrated and welded, and the contact width between the flange edge and the bottom of the second hole segment is W3, 1.5mm≤W3≤6mm.

[0014] In an optional embodiment, the joint surface between the flange edge and the bottom of the second hole segment is a first plane; the explosion-proof valve body is located between the first plane and the second end surface of the assembly body along the X2 direction.

[0015] In an optional embodiment, the mounting hole also includes a third hole segment, the inner diameter of the third hole segment is larger than the inner diameter of the second hole segment, the third hole segment is close to the first end face of the assembly body, the depth of the third hole segment is D, the thickness of the assembly body is H, 0.1mm≤D≤0.5H.

[0016] In a second aspect, the present invention further provides a battery pack comprising the battery cell described in any one of the above technical solutions.

[0017] Beneficial effect: Since the battery pack includes the battery cell, it has the same effect as the battery cell and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic structural diagram of a battery cover assembly of a battery cell according to an embodiment of the present invention;

[0020] Figure 2 for Figure 1A schematic diagram of the structure of the battery cover assembly facing backwards is shown;

[0021] Figure 3 for Figure 1 An exploded view of the cell cover assembly shown;

[0022] Figure 4 for Figure 1 A top view of the cell cover assembly shown;

[0023] Figure 5 For along Figure 4 Sectional view at AA in the middle;

[0024] Figure 6 for Figure 5 A partial enlarged view of point C in the middle;

[0025] Figure 7 This is a partial enlarged view of point C when penetration welding is used.

[0026] Figure 8 It is a partial enlarged view of the mounting hole at position C;

[0027] Fig. 9 It is a partial enlarged view of the explosion-proof valve at C;

[0028] Fig.10 For along Figure 4 Cross-sectional view at the middle BB.

[0029] Description of reference numerals:

[0030] 1. Cover plate; 11. Mounting hole; 111. First hole section; 112. Second hole section; 113. Third hole section; 2. Explosion-proof valve; 21. Explosion-proof valve body; 22. Flange edge; 23. Transition edge; 3. Pole; 31. Pole body; 32. Pole bottom plate; 4. First plastic part; 5. Second plastic part; 6. Riveting block. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0032] Combine the following Figures 1 to 10 , describing an embodiment of the present invention.

[0033] According to an embodiment of the present invention, in a first aspect, a battery cell is provided, comprising an assembly body and an explosion-proof valve 2. The assembly body has a first end face along the X1 direction and a second end face along the X2 direction, and the assembly body is provided with a mounting hole 11 penetrating the first end face and the second end face thereof; the explosion-proof valve 2 comprises an explosion-proof valve body 21, a flange edge 22 provided on the outer ring of the explosion-proof valve body 21, and a transition edge 23 connecting the explosion-proof valve body 21 and the flange edge 22, and the flange edge 22 protrudes from the plane where the explosion-proof valve body 21 is located; the explosion-proof valve body 21 is provided in the mounting hole 11, and the flange edge 22 is provided at the first end face of the mounting hole 11 along the X1 direction, and is welded to the assembly body.

[0034] In the battery cell provided by the present invention, since the explosion-proof valve 2 is provided with a transition edge 23 and a flange edge 22, and the transition edge 23 and the flange edge 22 protrude from the plane where the explosion-proof valve body 21 is located, the explosion-proof valve 2 is welded to the assembly body through the flange edge 22. Compared with the direct welding of the explosion-proof valve body 21 to the assembly body, the conduction path of the welding heat can be effectively extended, and the explosion-proof valve 2 is prevented from being deformed or cracked due to the welding heat, thereby ensuring that the explosion-proof valve 2 can be opened under the design pressure, and ensuring the safety of the battery cell and the battery pack.

[0035] Specifically, in the battery cell, the assembly body of the explosion-proof valve 2 includes a battery cell cover assembly or a housing. That is, the explosion-proof valve 2 can be arranged on the battery cell cover assembly or on the housing.

[0036] When the assembly body is a shell, the X1-X2 direction is along the wall thickness direction of the shell. Regardless of whether the assembly body is a battery cover assembly or a shell, the X1 direction is the direction away from the pole group in the shell, and the X2 direction is the direction toward the pole group.

[0037] For the sake of convenience, the present invention is described below by taking the solution in which the explosion-proof valve 2 is assembled on the battery cover assembly as an example.

[0038] The battery cell cover plate assembly includes a cover plate 1, which has a first end face along the X1 direction and a second end face along the X2 direction. The assembly body is provided with a mounting hole 11 passing through the first end face and the second end face thereof; the explosion-proof valve body 21 is provided at the mounting hole 11, and the flange edge 22 is provided at the first end face of the mounting hole 11 along the X1 direction and is welded to the cover plate 1.

[0039] In some embodiments, the mounting hole 11 is a stepped hole including a first hole section 111 and a second hole section 112, the inner diameter of the second hole section 112 is larger than the inner diameter of the first hole section 111, the second hole section 112 is close to the first end surface of the cover plate 1, the explosion-proof valve body 21 is arranged in the first hole section 111, and the flange edge 22 is arranged in the second hole section 112.

[0040] Specifically, in some embodiments, Figure 6As shown, the flange edge 22 and the end surface of the second hole section 112 are butt welded. In other embodiments, such as Figure 7 As shown, the flange edge 22 and the bottom of the second hole section 112 are penetrated and welded.

[0041] In some embodiments, the angle between the transition edge 23 and the explosion-proof valve body 21 is α, 90°≤α≤175°; the angle between the transition edge 23 and the flange edge 22 is β, vertical, 90°≤β≤175°; there is a gap between the transition edge 23 and the inner wall of the first hole section 111.

[0042] This arrangement can further improve the rigidity of the explosion-proof valve 2 and its ability to resist deformation. During the use of the battery, even if the explosion-proof valve 2 is affected by external forces, it will not be easily deformed, thereby ensuring the opening pressure of the explosion-proof valve 2. In the case where a or β is less than 90°, the explosion-proof valve 2 cannot be separated from the mold during processing, which is not conducive to the processing and molding of the explosion-proof valve 2. In the case where a or β is greater than 175°, the design of the opening area size of the explosion-proof valve 2 is affected, that is, the opening area design of the explosion-proof valve 2 is smaller, resulting in the inability to exhaust in time during thermal runaway, affecting the safety of the battery.

[0043] Specifically, there is a gap between the transition edge 23 and the inner wall of the first hole section 111, which increases air insulation and can further improve the insulation effect.

[0044] In some embodiments, the width of the gap is W1, 0.3 mm ≤ W1 ≤ 10 mm.

[0045] Specifically, W1 is less than 0.3 mm, that is, the gap between the transition edge 23 and the inner wall of the first hole section 111 is too small, and the explosion-proof valve 2 is difficult to assemble with the cover plate 1. In addition, the explosion-proof valve 2 is easily deformed during assembly, which can easily cause scratch damage to the explosion-proof valve 2. W1 is greater than 10 mm, that is, the gap between the transition edge 23 and the inner wall of the first hole section 111 is too large, and the distance between the explosion-proof valve 2 and the cover plate 1 is large, resulting in a small opening area design of the explosion-proof valve 2, which is not recommended.

[0046] In some embodiments, the flange edge 22 is arranged at the bottom of the second hole segment 112, and the flange edge 22 and the second hole segment 112 are welded to the first end face along the X1 direction. The contact width between the flange edge 22 and the bottom of the second hole segment 112 is W2, 0.8mm≤W2≤4mm.

[0047] like Figure 5 and Figure 6As shown, the flange edge 22 and the second hole section 112 are welded to the seam at the first end face along the X1 direction. If W2 is less than 0.8 mm, that is, the contact width of the flange edge 22 and the second hole section 112 at the bottom of the hole is too small, the overlap distance between the explosion-proof valve 2 and the cover plate 1 is small, and welding is impossible. If W2 is greater than 4 mm, that is, the contact width of the flange edge 22 and the second hole section 112 at the bottom of the hole is too large, the overlap distance between the explosion-proof valve 2 and the cover plate 1 is large, and processing is difficult. At the same time, it will increase the cost of the explosion-proof valve 2, and it is not recommended to use it.

[0048] In some embodiments, the flange edge 22 is disposed at the bottom of the second hole segment 112 and the two are penetrated and welded, and the contact width between the flange edge 22 and the bottom of the second hole segment 112 is W3, 1.5 mm≤W3≤6 mm.

[0049] like Figure 7 As shown, the flange edge 22 and the bottom of the second hole section 112 are penetrated and welded. W3 is less than 1.5mm, that is, the contact width of the flange edge 22 and the bottom of the second hole section 112 is too small, and the overlap distance between the explosion-proof valve 2 and the cover plate 1 is small, resulting in the inability to weld. W3 is greater than 6mm, that is, the contact width of the flange edge 22 and the bottom of the second hole section 112 is too large, and the overlap distance between the explosion-proof valve 2 and the cover plate 1 is large, which makes processing difficult and weakens the strength of the cover plate 1. In addition, because the contact area is too large, the material used for the explosion-proof valve 2 is increased, which in turn increases the cost of the explosion-proof valve 2. It is not recommended to use it.

[0050] In some embodiments, the joint surface between the flange edge 22 and the bottom of the second hole section 112 is a first plane P1. Figure 6 As shown; the explosion-proof valve body 21 is located between the first plane and the second end surface of the battery cover assembly along the X2 direction.

[0051] Specifically, the second end face of the cell cover plate assembly along the X2 direction refers to the end face farthest from the first end face of the cover plate 1. Further, the cell cover plate assembly also includes a pole 3, the pole 3 includes a pole body 31 and a pole bottom plate 32 arranged at one end of the pole body 31, the cover plate 1 is provided with a pole assembly hole, the pole body 31 is arranged in the pole assembly hole, and both ends pass through the pole assembly hole, and the pole bottom plate 32 is located at the second end face of the cover plate 1; along the X2 direction, the end face of the pole bottom plate 32 away from the pole body 31 is a second plane P2, as shown in FIG. Figure 5 As shown, that is, the second end surface of the cell cover assembly along the X2 direction is the plane shown as P2. The explosion-proof valve body 21 is located between the first plane P1 and the second plane P2.

[0052] Specifically, when the cell cover plate assembly is assembled in the cell housing, the first end surface of the cover plate along the X1 direction is away from the inner cavity of the cell housing, and the second end surface of the cover plate along the X2 direction faces the inner cavity of the cell housing.

[0053] Specifically, the flange edge 22 and the transition edge 23 play the role of extending the heat conduction path. The longer the extension length of the flange edge 22 and the transition edge 23 is, the longer the heat conduction path is, and the better the heat insulation effect on the explosion-proof valve body 21 is. The width of the flange edge 22 (i.e., the length along the heat conduction direction) is defined for different welding methods, and the length of the transition edge 23 along the heat conduction direction is defined here.

[0054] The explosion-proof valve body 21 is arranged between the first plane P1 and the second plane P2, which can ensure that when the explosion-proof valve 2 and the cover plate 1 are welded and assembled, the influence of welding heat on the explosion-proof valve body 21 is reduced, thereby ensuring that the explosion-proof valve body 21 can open the valve to release pressure under the designed pressure, and ensure the safety performance of the battery cell and the battery pack. At the same time, facing the second end surface of the cover plate 1, the explosion-proof valve body 21 does not exceed the bottom surface of the pole 3, so that it can ensure that the space in the thickness direction of the battery cell cover plate assembly is not occupied.

[0055] The pole 3 is provided with a pole body 31 and a pole bottom plate 32. The pole body 31 passes through the pole assembly hole, and the first end extends out of the cover plate 1, which plays the role of conducting the electric energy inside the battery cell. The pole bottom plate 32 is located on the second end surface of the cover plate 1, one end of which is connected to the pole body 31, and the other end is used for conductive connection with the pole group, so that the electric energy inside the battery cell can be conducted to the pole body 31.

[0056] In some embodiments, the mounting hole 11 also includes a third hole section 113, the inner diameter of the third hole section 113 is greater than the inner diameter of the second hole section 112, the third hole section 113 is close to the first end surface of the cover plate 1, the depth of the third hole section 113 is D, the thickness of the cover plate 1 is H, 0.1mm≤D≤0.5H.

[0057] By setting the third hole section 113, that is, forming a sink between the third hole section 113 and the second hole section 112, and controlling the depth D of the third hole section 113 within the range of 0.1mm to 0.5mm, the weld formed by welding the explosion-proof valve 2 and the cover plate 1 can be prevented from protruding from the first end surface of the cover plate 1, thereby not occupying the space in the thickness direction of the battery cover plate assembly. When D is too small, such as in Experimental Case 3 and Experimental Case 20, where D = -0.5mm, the explosion-proof valve 2 protrudes from the lower surface of the cover plate 1, occupying the internal space of the battery, which is not conducive to improving the volume energy density of the battery, and is not recommended for use.

[0058] In addition, when the assembly body is a housing, H is the wall thickness of the housing.

[0059] In some embodiments, the cell cover assembly further includes a first plastic part 4, a second plastic part 5 and a rivet block 6. The pole 3 is fixed to the cover 1 by the rivet block 6. The first plastic part 4 is arranged between the pole 3 and the cover 1 on the first end face of the cover 1, and the second plastic part 5 is arranged between the pole 3 and the cover 1 on the second end face of the cover 1, so as to ensure the insulation connection between the pole 3 and the cover 1.

[0060] In order to verify the technical effect of the present invention, a specific implementation case is provided below for testing. The test results are shown in Tables 1 to 4.

[0061] Table 1: Table 2:

[0062]

[0063] Table 3:

[0064] Table 4:

[0065]

[0066] When the explosion-proof valve is arranged on the battery cell cover assembly, the battery cell also includes a shell and a pole group, the shell has an open end; the pole group is arranged in the accommodating cavity of the shell; the battery cell cover assembly is arranged at the open end of the shell, and the pole group is encapsulated in the shell.

[0067] According to an embodiment of the present invention, in a second aspect, a battery pack is further provided, comprising the battery cell described in any one of the above embodiments.

[0068] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0069] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cell, characterized in that: include: An assembly body, the assembly body having a first end face along the X1 direction and a second end face along the X2 direction, and the assembly body is provided with a mounting hole penetrating the first end face and the second end face; An explosion-proof valve, comprising an explosion-proof valve body, a flange edge arranged on the outer ring of the explosion-proof valve body, and a transition edge connecting the explosion-proof valve body and the flange edge, wherein the flange edge and the transition edge protrude from the plane where the explosion-proof valve body is located; the explosion-proof valve body is arranged in the mounting hole, the flange edge is arranged on the first end face of the mounting hole along the X1 direction, and is welded to the assembly body.

2. The battery cell according to claim 1, characterized in that: The mounting hole is a stepped hole including a first hole section and a second hole section, the inner diameter of the second hole section is larger than the inner diameter of the first hole section, the second hole section is close to the first end face of the assembly body, the explosion-proof valve body is arranged in the first hole section, and the flange edge is arranged in the second hole section.

3. The battery cell according to claim 2, characterized in that: The included angle between the transition edge and the explosion-proof valve body is α, 90°≤α≤175°; the included angle between the transition edge and the flange edge is β, 90°≤β≤175°.

4. The battery cell according to claim 2 or 3, characterized in that: There is a gap between the transition edge and the inner wall of the first hole segment.

5. The battery cell according to claim 4, characterized in that: The width of the gap is W1, 0.3mm≤W1≤10mm.

6. The battery cell according to claim 2 or 3, characterized in that: The flange edge is arranged at the bottom of the second hole segment, and the flange edge and the second hole segment are welded to each other along the first end surface of the X1 direction, and the contact width between the flange edge and the bottom of the second hole segment is W2, 0.8mm≤W2≤4mm.

7. The battery cell according to claim 2 or 3, characterized in that: The flange edge is arranged at the bottom of the second hole section, and the two are penetrated and welded, and the contact width between the flange edge and the bottom of the second hole section is W3, 1.5mm≤W3≤6mm.

8. The battery cell according to claim 2 or 3, characterized in that: The joint surface between the flange edge and the bottom of the second hole section is a first plane; the explosion-proof valve body is located between the first plane and the second end surface of the assembly body along the X2 direction.

9. The battery cell according to claim 2 or 3, characterized in that: The mounting hole also includes a third hole segment, the inner diameter of the third hole segment is greater than the inner diameter of the second hole segment, the third hole segment is close to the first end surface of the assembly body, the depth of the third hole segment is D, the thickness of the assembly body is H, 0.1mm≤D≤0.5H.

10. A battery pack, characterized in that: A battery cell comprising the battery cell according to any one of claims 1 to 9.

Images