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, and the mounting hole is provided with a first sinking table which sinks from the second end face of the assembling main body to the first end face of the assembling main body; the anti-explosion valve comprises an anti-explosion valve body, a baffle ring extending from the edge of the anti-explosion valve to the second end face of the assembly body and a flange edge arranged on the outer wall of the baffle ring and away from the anti-explosion valve body, the anti-explosion valve body is arranged in the installation hole, and the flange edge is arranged on the first sinking table and welded to the assembly body. A heat insulation gap is formed between the baffle ring and the inner wall of the mounting hole. According to the explosion-proof valve, the conduction path of welding heat can be effectively prolonged, the explosion-proof valve is prevented from being deformed and cracked due to the welding heat, the explosion-proof valve can be opened under the designed pressure, the safety of the battery cell and the battery pack is ensured, and the explosion-proof valve can be ensured not to be influenced by electrolyte when the electrolyte is injected, so that the safety performance of the battery cell 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] The cell cover assembly is an important component of the cell. It is assembled with the cell shell to form a closed cavity, encapsulating the electrode group inside.

[0004] The battery cell cover plate assembly includes a cover plate and an explosion-proof valve, which is fixedly connected to the cover plate by welding. However, 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 by the heat. In addition, for the battery cell with the injection hole located next to the explosion-proof valve, when the electrolyte is injected, the electrolyte is easy to contaminate the notch of the explosion-proof valve, affecting the normal opening of the explosion-proof valve, 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 welding heat, and the explosion-proof valve is easily contaminated by electrolyte.

[0006] In a first aspect, the present invention provides a battery cell, including 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; the assembly body is provided with a mounting hole, and the mounting hole has a first sinking platform recessed from the second end face of the assembly body to the first end face of the assembly body; the explosion-proof valve includes an explosion-proof valve body, a retaining ring extending from the edge of the explosion-proof valve body to the second end face of the assembly body, and a flange edge arranged on the outer wall of the retaining ring and away from the explosion-proof valve body, the explosion-proof valve body is arranged in the mounting hole, and the flange edge is arranged on the first sinking platform and welded to the assembly body.

[0007] Beneficial effect: The battery cell provided by the present invention has a flange edge provided on the explosion-proof valve, and the flange edge protrudes 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 welding heat can be effectively extended to prevent the explosion-proof valve from being deformed or cracked due to welding heat, thereby ensuring that the explosion-proof valve can be opened under the designed pressure and ensuring the safety of the battery cell and battery pack. At the same time, for the battery cell with the injection hole set next to the explosion-proof valve, the retaining ring can also prevent the electrolyte from contaminating the explosion-proof valve body when the electrolyte is injected, ensuring that the explosion-proof valve is not affected by the electrolyte, thereby ensuring the safety performance of the battery cell.

[0008] In an optional embodiment, a heat-insulating gap exists between the retaining ring and the inner wall of the mounting hole.

[0009] In an optional implementation, the width of the thermal insulation gap is W1, 0.3 mm ≤ W1 ≤ 10 mm.

[0010] In an optional implementation, the flange edge and the side wall of the first sinker are butt welded, and the contact width between the flange edge and the first sinker is W2, 0.8mm≤W2≤4mm.

[0011] In an optional implementation, the flange edge and the first sinker are penetrated and welded, and the contact width between the flange edge and the first sinker is W3, 1.5mm≤W3≤6mm.

[0012] In an optional embodiment, the joint surface between the flange edge and the first sink is a first plane; the explosion-proof valve body is located between the first plane and the first end surface of the assembly body along the X1 direction.

[0013] In an optional embodiment, the mounting hole has a second sink recessed from the second end surface of the assembly body toward the first sink, the depth of the second sink is D, the thickness of the assembly body is H, and the following is satisfied: 0mm<D≤0.5H.

[0014] In an optional implementation, the angle between the retaining ring and the explosion-proof valve body is α, 90°≤α≤175°; the angle between the retaining ring and the flange edge is β, 90°≤β≤175°.

[0015] In an optional embodiment, it further includes a shell, a pole group and a cell cover assembly. The shell has an open end; the pole group is arranged in the housing cavity of the shell; the cell cover assembly is arranged at the open end of the shell to encapsulate the pole group in the shell; the assembly body is the shell or the cell cover assembly.

[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 1 A schematic diagram of the structure of the back of the battery cover assembly 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 sink; 112. Second sink; 113. Thermal insulation gap; 2. Explosion-proof valve; 21. Explosion-proof valve body; 22. Flange; 23. Retaining ring; 3. Pole; 31. Pole body; 32. Pole bottom plate; 4. First plastic part; 5. Second plastic part; 6. Riveting block; 7. Injection hole. 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; the assembly body is provided with a mounting hole 11, and the mounting hole 11 has a first sink 111 recessed from the second end face of the assembly body to the first end face of the assembly body; the explosion-proof valve 2 comprises an explosion-proof valve body 21, a retaining ring 23 extending from the edge of the explosion-proof valve body 21 to the second end face of the assembly body, and a flange edge 22 arranged on the outer wall of the retaining ring 23 and away from the explosion-proof valve body 21, the explosion-proof valve body 21 is arranged in the mounting hole 11, and the flange edge 22 is arranged on the first sink 111 and welded to the assembly body.

[0034] The battery cell provided by the present invention has a flange edge 22 disposed on the explosion-proof valve 2, and the flange edge 22 protrudes 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 explosion-proof valve body 21 being directly welded to the assembly body, the conduction path of welding heat can be effectively extended, and the explosion-proof valve 2 is prevented from being deformed or cracked due to 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. At the same time, for the battery cell with the injection hole 7 disposed next to the explosion-proof valve 2, the retaining ring 23 can also prevent the electrolyte from contaminating the explosion-proof valve body 21 when the electrolyte is injected, ensuring that the explosion-proof valve 2 is not affected by the electrolyte, thereby ensuring the safety performance of the battery cell.

[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 cover plate 1 has a first end face along the X1 direction and a second end face along the X2 direction; the cover plate 1 is provided with a mounting hole 11, and the mounting hole 11 has a first sink 111 recessed from the second end face of the cover plate 1 to the first end face of the cover plate 1; the explosion-proof valve 2 includes an explosion-proof valve body 21, a retaining ring 23 extending from the edge of the explosion-proof valve body 21 to the second end face of the cover plate 1, and a flange edge 22 arranged on the outer wall of the retaining ring 23 and away from the explosion-proof valve body 21, the explosion-proof valve body 21 is arranged in the mounting hole 11, the flange edge 22 is arranged on the first sink 111, and is welded to the cover plate 1.

[0039] In some embodiments, a heat insulating gap 113 exists between the retaining ring 23 and the inner wall of the mounting hole 11 .

[0040] In this configuration, since there is a heat insulation gap 113 between the retaining ring 23 and the inner wall of the mounting hole 11 , air heat insulation is increased, thereby improving the heat insulation effect on the explosion-proof valve body 21 .

[0041] In some embodiments, the width of the thermal insulation gap 113 is W1, 0.3 mm≤W1≤10 mm.

[0042] Specifically, when W1 is less than 0.3 mm, that is, the width of the insulation gap 113 is too small, the explosion-proof valve 2 and the cover plate 1 are difficult to assemble, and the explosion-proof valve 2 is easily deformed during assembly, which may easily cause scratches and damage to the explosion-proof valve 2. When W1 is greater than 10 mm, that is, the width of the insulation gap 113 is too large, 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.

[0043] In some embodiments, the flange edge 22 and the side wall of the first sinking platform 111 are butt welded, and the contact width between the flange edge 22 and the first sinking platform 111 is W2, and 0.8 mm≤W2≤4 mm.

[0044] like Figure 5 and Figure 6 As shown, the flange edge 22 and the first sink 111 are welded. If W2 is less than 0.8 mm, that is, the contact width between the flange edge 22 and the first sink 111 is too small, the contact width 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 between the flange edge 22 and the first sink 111 is too large, the contact width 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.

[0045] In some embodiments, the flange edge 22 and the first sinker 111 are penetrated and welded, and the contact width between the flange edge 22 and the first sinker 111 is W3, and 1.5 mm≤W3≤6 mm.

[0046] like Figure 7 As shown, the flange edge 22 and the first sink 111 are penetrated and welded. W3 is less than 1.5mm, that is, the contact width between the flange edge 22 and the first sink 111 is too small, and the contact width between the explosion-proof valve 2 and the cover plate 1 is small, resulting in failure to weld. W3 is greater than 6mm, that is, the contact width between the flange edge 22 and the first sink 111 is too large, and the contact width 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.

[0047] In some embodiments, the joint surface between the flange edge 22 and the first sink 111 is a first plane P1. Figure 6 As shown; the explosion-proof valve body 21 is located between the first plane and the first end surface of the battery cell cover assembly along the X1 direction.

[0048] Specifically, the first end face of the cell cover plate assembly along the X1 direction refers to the end face farthest from the second end face of the cover plate 1 along the X1 direction. Further, the cell cover plate assembly further includes a pole 3 and a rivet block 6, the pole 3 is arranged on the cover plate 1 through the rivet block 6, and the first end face of the rivet block 6 is the second plane P2, as shown in FIG. Figure 5 As shown, that is, the first end surface of the cell cover assembly along the X1 direction is the plane shown as P2, and the explosion-proof valve body 21 is located between the first plane P1 and the second plane.

[0049] 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.

[0050] Specifically, the flange 22 and the retaining ring 23 play the role of extending the heat conduction path. The longer the extension length of the flange 22 and the retaining ring 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 22 (i.e., the length along the heat conduction direction) is defined for different welding methods, and the length of the retaining ring 23 along the heat conduction direction is defined here.

[0051] The explosion-proof valve body 21 is arranged between the first plane P1 and the second plane, 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, ensuring the safety performance of the battery cell and the battery pack, and ensuring that the explosion-proof valve body 21 is not contaminated by the electrolyte. At the same time, facing the first end face of the cover plate 1, the explosion-proof valve body 21 does not exceed the first end face of the pole 3 along the X1 direction or the first end face of the riveting block 6 along the X1 direction, so that it can ensure that the space in the thickness direction of the battery cell cover plate 1 is not occupied.

[0052] In some embodiments, the first end surface of the pole 3 along the X1 direction is recessed in the first end surface of the riveting block 6 along the X1 direction, and the explosion-proof valve body 21 is located between the first plane P1 and the first end surface of the cell cover assembly along the X1 direction.

[0053] In some embodiments, the mounting hole 11 has a second recessed platform 112 that is recessed from the second end surface of the cover plate 1 toward the first recessed platform 111 , the depth of the second recessed platform 112 is D, the thickness of the cover plate 1 is H, and the following is satisfied: 0mm<D≤0.5H.

[0054] By setting the second sink 112 and controlling the depth D of the second sink 112 within the range of 0.1mm to 0.5mm, the weld formed by the welding of 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 cell 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. When D is too large, there is no abnormality in the assembly of the explosion-proof valve 2, the explosion-proof valve 2 is welded to the cover plate 1, and the cover plate 1 and the part of the cover plate supporting the explosion-proof valve 2 are deformed, and it is not recommended for use.

[0055] In some embodiments, 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 on the second end face of the cover plate 1.

[0056] 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. The first end of the pole body 31 extends out of the cover plate 1 to conduct 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.

[0057] In some embodiments, the cell cover assembly further includes a first plastic part 4 and a second plastic part 5. The pole 3 is fixed to the cover 1 by a 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.

[0058] In some embodiments, the angle between the retaining ring 23 and the explosion-proof valve body 21 is α, 90°≤α≤175°; the angle between the retaining ring 23 and the flange edge 22 is β, 90°≤β≤175°.

[0059] 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.

[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:

[0062]

[0063] Table 2:

[0064]

[0065] Table 3:

[0066]

[0067] Table 4:

[0068]

[0069] In some embodiments, it also includes a shell, a pole group and a cell cover assembly. The shell has an open end; the pole group is arranged in the housing cavity of the shell; the cell cover assembly is arranged at the open end of the shell, and the pole group is encapsulated in the shell, and the assembly body is the shell or the cell cover assembly.

[0070] 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.

[0071] Since the battery pack includes battery cells and has the same effect as the battery cells, it will not be described in detail here.

[0072] 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; the assembly body is provided with a mounting hole, the mounting hole having a first sinking platform recessed from the second end face of the assembly body to the first end face of the assembly body; An explosion-proof valve, comprising an explosion-proof valve body, a retaining ring extending from the edge of the explosion-proof valve body to the second end face of the assembly body, and a flange edge arranged on the outer wall of the retaining ring and away from the explosion-proof valve body, the explosion-proof valve body is arranged in the mounting hole, the flange edge is arranged on the first sinker, and is welded to the assembly body.

2. The battery cell according to claim 1, characterized in that: A heat-insulating gap exists between the retaining ring and the inner wall of the mounting hole.

3. The battery cell according to claim 2, characterized in that: The width of the thermal insulation gap is W1, 0.3mm≤W1≤10mm.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The flange edge and the side wall of the first sinker are butt welded, and the contact width between the flange edge and the first sinker is W2, 0.8mm≤W2≤4mm.

5. The battery cell according to any one of claims 1 to 3, characterized in that: The flange edge and the first sinker are penetrated and welded, and the contact width between the flange edge and the first sinker is W3, 1.5mm≤W3≤6mm.

6. The battery cell according to any one of claims 1 to 3, characterized in that: The joint surface between the flange edge and the first sink is a first plane; the explosion-proof valve body is located between the first plane and the first end surface of the assembly body along the X1 direction.

7. The battery cell according to any one of claims 1 to 3, characterized in that: The mounting hole has a second sunken platform sunken from the second end surface of the assembly body toward the first sunken platform, and the depth of the second sunken platform is D, 0mm<D≤0.5mm.

8. The battery cell according to any one of claims 1 to 3, characterized in that: The included angle between the retaining ring and the explosion-proof valve body is α, 90°≤α≤175°; the included angle between the retaining ring and the flange edge is β, 90°≤β≤175°.

9. The battery cell according to any one of claims 1 to 3, characterized in that: Also includes: a housing having an open end; A pole group, which is arranged in the accommodating cavity of the shell; A cell cover assembly, the cell cover assembly being disposed at the open end of the shell and encapsulating the electrode group in the shell; The assembly body is the shell or the battery cover assembly.

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

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