Battery cell and battery pack

Abstract

The application relates to the technical field of batteries, and discloses a battery cell and a battery pack. The battery cell comprises an assembly body and an explosion-proof valve. The assembly body is provided with a mounting hole; the explosion-proof valve comprises an explosion-proof valve body, a flange edge arranged at the outer circle of the explosion-proof valve body, and a transition edge connecting the explosion-proof valve body and the flange edge, 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 surface of the mounting hole, and the flange edge is welded with the assembly body. The battery cell provided by the application is provided with the flange edge of the explosion-proof valve, the flange edge protrudes from the plane where the explosion-proof valve body is located, the explosion-proof valve is welded with the assembly body through the flange edge, compared with the direct welding of the explosion-proof valve body with the assembly body, 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, so that the explosion-proof valve can be opened under the design pressure, and the safety of the battery cell and the battery pack is ensured.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to battery cells and battery packs. Background Technology

[0002] The global battery cell market has been expanding in recent years and is expected to continue its rapid growth. Technologically, the energy density, safety, and cycle life of battery cells are constantly improving.

[0003] An important component in a 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 plate or housing of the battery cell by welding. However, during the welding process of the explosion-proof valve, the high heat of welding is conducted to the explosion-proof valve, causing the explosion-proof valve to be easily deformed or even cracked due to heat, thus affecting the safety of the battery cell. Summary of the Invention

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

[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, and the assembly body is provided with a mounting hole penetrating the first end face and the second end face; the explosion-proof valve includes an explosion-proof valve body, a flange edge disposed on the outer ring of the explosion-proof valve body, and a transition edge connecting the explosion-proof valve body and the flange edge, the flange edge and the transition edge protruding from the plane of the explosion-proof valve body; the explosion-proof valve body is disposed in the mounting hole, the flange edge is disposed on the first end face of the mounting hole along the X1 direction, and is welded to the assembly body.

[0007] Beneficial effects: The battery cell provided by this invention has an explosion-proof valve with a transition edge and a flange edge, and the transition edge and 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 explosion-proof valve body being directly welded to the assembly body, this can effectively extend the conduction path of welding heat, prevent the explosion-proof valve from deforming or cracking due to welding heat, and thus ensure that the explosion-proof valve can open under the design pressure, ensuring the safety of the battery cell and battery pack.

[0008] In one 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 located in the first hole section, and the flange edge is located in the second hole section.

[0009] In one optional embodiment, 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, perpendicular, 90°≤β≤175°.

[0010] In one alternative implementation, a gap exists between the transition edge and the inner wall of the first hole segment.

[0011] In one alternative implementation, the width of the gap is W1, where 0.3mm ≤ W1 ≤ 10mm.

[0012] In one optional embodiment, the flange edge is located at the bottom of the hole in the second hole section, and the first end face of the flange edge and the second hole section along the X1 direction is welded together. The contact width between the flange edge and the bottom of the hole in the second hole section is W2, 0.8mm≤W2≤4mm.

[0013] In one optional embodiment, the flange edge is located at the bottom of the hole in the second hole section, and the two are welded through each other. The contact width between the flange edge and the bottom of the hole in the second hole section is W3, where 1.5mm ≤ W3 ≤ 6mm.

[0014] In one alternative embodiment, the mating 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 face of the assembly body along the X2 direction.

[0015] In one optional embodiment, the mounting hole further includes a third hole segment with an inner diameter greater than that of the second hole segment. The third hole segment is located close to the first end face of the assembly body, and the depth of the third hole segment is D. The thickness of the assembly body is H, where 0.1 mm ≤ D ≤ 0.5 H.

[0016] Secondly, the present invention also provides a battery pack comprising the battery cell described in any of the above technical solutions.

[0017] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells, which will not be elaborated here. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the structure of a battery cell cover plate assembly according to an embodiment of the present invention;

[0020] Figure 2 for Figure 1A schematic diagram of the back structure of the battery cell cover assembly shown;

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

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

[0023] Figure 5 For along Figure 4 Sectional view at point AA;

[0024] Figure 6 for Figure 5 A magnified view of a section at point C;

[0025] Figure 7 This is a magnified view of point C when using through-welding.

[0026] Figure 8 This is a magnified view of the mounting hole at point C.

[0027] Figure 9 This is a magnified view of the explosion-proof valve at point C.

[0028] Figure 10 For along Figure 4 Sectional view at point BB.

[0029] Explanation of reference numerals in the attached figures:

[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 post; 31. Pole post body; 32. Pole post base plate; 4. First plastic part; 5. Second plastic part; 6. Riveting block. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The following is combined Figures 1 to 10 The following describes embodiments of the present invention.

[0033] According to an embodiment of the present invention, in a first aspect, a battery cell is provided, including 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; the explosion-proof valve 2 includes an explosion-proof valve body 21, a flange edge 22 disposed 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, the flange edge 22 protruding from the plane of the explosion-proof valve body 21; the explosion-proof valve body 21 is disposed in the mounting hole 11, the flange edge 22 is disposed on the first end face of the mounting hole 11 along the X1 direction, and is welded to the assembly body.

[0034] The battery cell provided by this invention features an explosion-proof valve 2 with a transition edge 23 and a flange edge 22, both of which protrude from the plane of the explosion-proof valve body 21. The explosion-proof valve 2 is welded to the assembly body via the flange edge 22. Compared to welding the explosion-proof valve body 21 directly to the assembly body, this effectively extends the heat conduction path and prevents the explosion-proof valve 2 from deforming or cracking due to welding heat. This ensures that the explosion-proof valve 2 can open under the design pressure, guaranteeing the safety of the battery cell and battery pack.

[0035] Specifically, within the battery cell, the assembly body for the explosion-proof valve 2 includes either a battery cell cover assembly or a housing. That is, the explosion-proof valve 2 can be mounted on either the battery cell cover assembly or the housing.

[0036] When the main assembly is a housing, the X1-X2 direction is along the wall thickness of the housing. Regardless of whether the main assembly is a cell cover assembly or a housing, the X1 direction is always away from the electrode group inside the housing, and the X2 direction is always towards the electrode group.

[0037] For ease of explanation, the following description uses the example of the explosion-proof valve 2 being assembled in the battery cell cover assembly to illustrate the present invention.

[0038] The battery cell cover 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 that penetrates the first end face and the second end face. The explosion-proof valve body 21 is provided in the mounting hole 11, and the flange edge 22 is provided in 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 face of the cover plate 1. The explosion-proof valve body 21 is disposed in the first hole section 111, and the flange edge 22 is disposed in the second hole section 112.

[0040] Specifically, in some embodiments, such as Figure 6As shown, the end faces of flange edge 22 and 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 welded through.

[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, perpendicular, 90°≤β≤175°; and there is a gap between the transition edge 23 and the inner wall of the first hole section 111.

[0042] This design further enhances the rigidity of the explosion-proof valve 2 and improves its resistance to deformation. Even if the valve is subjected to external forces during battery use, it will not easily deform, thus ensuring the opening pressure of the valve 2. If α or β is less than 90°, the explosion-proof valve 2 will be unable to detach from the mold during processing, which is detrimental to its forming. If α or β is greater than 175°, it affects the design of the opening area of ​​the explosion-proof valve 2, resulting in a smaller opening area. This could lead to insufficient venting in case of thermal runaway, affecting battery safety.

[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, where 0.3mm ≤ W1 ≤ 10mm.

[0045] Specifically, if W1 is less than 0.3mm, that is, the gap between the transition edge 23 and the inner wall of the first hole section 111 is too small, the explosion-proof valve 2 is difficult to assemble with the cover plate 1, and the explosion-proof valve 2 is prone to deformation during assembly, which can easily cause scratches on the explosion-proof valve 2. If W1 is greater than 10mm, that is, the gap between the transition edge 23 and the inner wall of the first hole section 111 is too large, the distance between the explosion-proof valve 2 and the cover plate 1 is too large, resulting in a smaller opening area of ​​the explosion-proof valve 2, and its use is not recommended.

[0046] In some embodiments, the flange edge 22 is disposed at the bottom of the hole of the second hole section 112, and the flange edge 22 and the first end face of the second hole section 112 are welded together along the X1 direction. The contact width between the flange edge 22 and the bottom of the hole of the second hole section 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 together at their first end faces along the X1 direction. If W2 is less than 0.8mm, meaning the contact width between the flange edge 22 and the bottom of the hole in the second hole section 112 is too small, the overlap distance between the explosion-proof valve 2 and the cover plate 1 is too small, making welding impossible. If W2 is greater than 4mm, meaning the contact width between the flange edge 22 and the bottom of the hole in the second hole section 112 is too large, the overlap distance between the explosion-proof valve 2 and the cover plate 1 is too large, making processing difficult and increasing the cost of the explosion-proof valve 2; therefore, its use is not recommended.

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

[0049] like Figure 7 As shown, the flange edge 22 and the bottom of the hole in the second hole section 112 are welded through. If W3 is less than 1.5mm, the contact width between the flange edge 22 and the bottom of the hole in the second hole section 112 is too small, resulting in a small overlap distance between the explosion-proof valve 2 and the cover plate 1, making welding impossible. If W3 is greater than 6mm, the contact width between the flange edge 22 and the bottom of the hole in the second hole section 112 is too large, resulting in a large overlap distance between the explosion-proof valve 2 and the cover plate 1, making processing difficult, weakening the strength of the cover plate 1, and increasing the material usage of the explosion-proof valve 2 due to the large contact area, thus increasing the cost of the explosion-proof valve 2. Therefore, its use is not recommended.

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

[0051] Specifically, the second end face of the cell cover assembly along the X2 direction refers to the end face furthest from the first end face of the cover plate 1. Further, the cell cover assembly also includes a terminal post 3, which includes a terminal post body 31 and a terminal post base plate 32 disposed at one end of the terminal post body 31. The cover plate 1 has a terminal post mounting hole, the terminal post body 31 is disposed in the terminal post mounting hole, and both ends penetrate the terminal post mounting hole. The terminal post base plate 32 is located on the second end face of the cover plate 1; along the X2 direction, the end face of the terminal post base plate 32 facing away from the terminal post body 31 is the second plane P2, such as... Figure 5 As shown, the second end face of the cell cover assembly along the X2 direction is the plane shown in 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 assembly is assembled in the cell housing, the first end face of the cover in the X1 direction is away from the inner cavity of the cell housing, and the second end face of the cover in the X2 direction is towards the inner cavity of the cell housing.

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

[0054] By positioning the explosion-proof valve body 21 between the first plane P1 and the second plane P2, the impact of welding heat on the explosion-proof valve body 21 during the welding assembly of the explosion-proof valve 2 and the cover plate 1 can be reduced. This ensures that the explosion-proof valve body 21 can open and release pressure under the designed pressure, guaranteeing the safety performance of the battery cell and battery pack. Simultaneously, facing the second end face of the cover plate 1, the explosion-proof valve body 21 does not extend beyond the bottom surface of the pole post 3, thus ensuring that it does not occupy space in the thickness direction of the battery cell cover plate assembly.

[0055] The electrode post 3 is provided with an electrode post body 31 and an electrode post base plate 32. The electrode post body 31 passes through the electrode post assembly hole, and its first end extends out of the cover plate 1, which serves to conduct electrical energy from inside the battery cell. The electrode post base plate 32 is located on the second end face of the cover plate 1. One end is connected to the electrode post body 31, and the other end is used for conductive connection with the electrode group, which enables the electrical energy inside the battery cell to be conducted to the electrode post body 31.

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

[0057] By setting a third hole segment 113, forming a countersunk platform between the third hole segment 113 and the second hole segment 112, and controlling the depth D of the third hole segment 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 face of the cover plate 1, thus not occupying the space in the thickness direction of the 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 volumetric energy density of the battery, and its use is not recommended.

[0058] Furthermore, when the main body of the assembly is a shell, H is the wall thickness of the shell.

[0059] In some embodiments, the cell cover assembly further includes a first plastic part 4, a second plastic part 5, and a riveting block 6. The terminal post 3 is fixed to the cover plate 1 by the riveting block 6. The first plastic part 4 is disposed between the terminal post 3 and the cover plate 1 on the first end face of the cover plate 1, and the second plastic part 5 is disposed between the terminal post 3 and the cover plate 1 on the second end face of the cover plate 1, thereby ensuring an insulating connection between the terminal post 3 and the cover plate 1.

[0060] To verify the technical effects of this invention, specific implementation examples are 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] When the explosion-proof valve is located in the cell cover assembly, the cell also includes a housing and an electrode assembly. The housing has an open end; the electrode assembly is located in the receiving cavity of the housing; the cell cover assembly is located at the open end of the housing and encapsulates the electrode assembly inside the housing.

[0070] According to an embodiment of the present invention, in a second aspect, a battery pack is also provided, comprising the battery cells described in any of the foregoing embodiments.

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

[0072] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric cell, characterized by, The application relates to a shell assembly body and an explosion-proof valve. The explosion-proof valve comprises an explosion-proof valve body, a flange edge arranged at the outer circle 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 at the first end face of the mounting hole along the X1 direction, and is welded with the assembly body. The included angle between the transition edge and the explosion-proof valve body is alpha, and 90 DEG <= alpha <= 175 DEG; the included angle between the transition edge and the flange edge is beta, and 90 DEG <= beta <= 175 DEG. The mounting hole is a stepped hole comprising a first hole section and a second hole section, the inner diameter of the second hole section is larger than that 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. The gap between the transition edge and the inner wall of the first hole section exists; the width of the gap is W1, and 0.3 mm <= W1 <= 10 mm. The flange edge is arranged at the hole bottom of the second hole section, the flange edge and the first end face of the second hole section along the X1 direction are butt welded, the contact width of the flange edge and the hole bottom of the second hole section is W2, and 0.8 mm <= W2 <= 4 mm.

2. The electric cell of claim 1, wherein, The flange edge is arranged at the hole bottom of the second hole section, and the flange edge and the hole bottom of the second hole section are penetration welded; the contact width of the flange edge and the hole bottom of the second hole section is W3, and 1.5 mm <= W3 <= 6 mm.

3. The electric cell of claim 1, wherein, The joint surface of the flange edge and the hole 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 face of the assembly body along the X2 direction.

4. The electric cell of claim 1, wherein, The mounting hole further comprises a third hole section, the inner diameter of the third hole section is larger than that of the second hole section, the third hole section is close to the first end face of the assembly body, the depth of the third hole section is D, the thickness of the assembly body is H, and 0.1 mm <= D <= 0.5H.

5. The electric cell of claim 1, wherein, The application further relates to an electric cell comprising the shell assembly body and the explosion-proof valve.

6. A battery pack, characterized by, The application further relates to an electric cell comprising the shell assembly body and the explosion-proof valve.

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