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, and the mounting hole has a first sink that is recessed from a second end surface of the assembly body to a first end surface of the assembly body; the explosion-proof valve comprises an explosion-proof valve body, a retaining ring that extends from an edge of the explosion-proof valve to the second end surface of the assembly body, and a flange edge that is arranged on an outer wall of the retaining ring and is away from the explosion-proof valve body, the explosion-proof valve body is arranged in the mounting hole, the flange edge is arranged in the first sink and is welded with the assembly body, and a heat insulation gap exists between the retaining ring and an inner wall of the mounting hole. The application can effectively prolong the conduction path of welding heat, prevent the explosion-proof valve from being deformed and cracked due to the welding heat, enable the explosion-proof valve to be opened under the design pressure, guarantee the safety of the battery cell and the battery pack, and ensure that the explosion-proof valve is not affected by the electrolyte when the electrolyte is injected, so that the safety performance of the battery cell is guaranteed.

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] The cell cover assembly is an important component of the cell. It is assembled with the cell housing to form a sealed cavity, encapsulating the electrode assembly inside.

[0004] The cell cover assembly includes a cover plate and an explosion-proof valve. The explosion-proof valve is fixedly connected to the cover plate by welding. However, due to the high heat of welding, the heat is conducted to the explosion-proof valve, causing the explosion-proof valve to be easily deformed or even cracked due to heat. In addition, for cells with the electrolyte injection hole located next to the explosion-proof valve, the electrolyte can easily contaminate the grooves on the explosion-proof valve when it is injected, affecting the normal opening of the explosion-proof valve and thus affecting the safety of the cell. Summary of the Invention

[0005] In view of this, the present invention provides a battery cell and battery pack to solve the problems of explosion-proof valves being easily deformed and cracked due to welding heat, and explosion-proof valves being easily contaminated by electrolyte.

[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; the assembly body is provided with a mounting hole having a first recessed platform extending 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 disposed on the outer wall of the retaining ring and away from the explosion-proof valve body; the explosion-proof valve body is disposed in the mounting hole, the flange edge is disposed on the first recessed platform, and is welded to the assembly body.

[0007] Beneficial effects: The battery cell provided by this invention features an explosion-proof valve with a flange that protrudes beyond the plane of the valve body. The explosion-proof valve is welded to the assembly body via the flange, which, compared to direct welding of the valve body to the assembly body, effectively extends the heat conduction path during welding. This prevents the explosion-proof valve from deforming or cracking due to welding heat, ensuring it can open under design pressure and guaranteeing the safety of the battery cell and battery pack. Furthermore, for battery cells with the electrolyte injection port located next to the explosion-proof valve, the retaining ring prevents electrolyte contamination of the valve body during injection, ensuring the valve is unaffected by the electrolyte and thus guaranteeing the battery cell's safety performance.

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

[0009] In one optional embodiment, the width of the thermal insulation gap is W1, where 0.3mm ≤ W1 ≤ 10mm.

[0010] In one alternative embodiment, the flange edge and the side wall of the first recessed platform are butt-welded, and the contact width between the flange edge and the first recessed platform is W2, 0.8mm≤W2≤4mm.

[0011] In one alternative embodiment, the flange edge and the first countersunk are through-welded, and the contact width between the flange edge and the first countersunk is W3, where 1.5mm≤W3≤6mm.

[0012] In one alternative embodiment, the mating surface between the flange edge and the first countersunk surface is a first plane; the explosion-proof valve body is located between the first plane and the first end face of the assembly body along the X1 direction.

[0013] In one alternative embodiment, the mounting hole has a second recessed platform recessed from the second end of the assembly body toward the first recessed platform, the depth of the second recessed platform being D, and the thickness of the assembly body being H, satisfying: 0mm<D≤0.5H.

[0014] In one optional embodiment, 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°.

[0015] In one alternative embodiment, the device further includes a housing, an electrode assembly, and a cell cover assembly. The housing has an open end; the electrode assembly is disposed in a receiving cavity of the housing; the cell cover assembly is disposed at the open end of the housing, encapsulating the electrode assembly within the housing; the assembly body is either the housing or the cell cover assembly.

[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 1 A 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 recessed platform; 112. Second recessed platform; 113. Insulation gap; 2. Explosion-proof valve; 21. Explosion-proof valve body; 22. Flange edge; 23. Retaining ring; 3. Pole post; 31. Pole post body; 32. Pole post base plate; 4. First plastic part; 5. Second plastic part; 6. Riveting block; 7. Injection hole. 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 with 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; the assembly body is provided with a mounting hole 11, the mounting hole 11 having a first recessed platform 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 includes an explosion-proof valve body 21, a retaining ring 23 extending from the edge of the explosion-proof valve body 21 toward the second end face of the assembly body, and a flange edge 22 disposed on the outer wall of the retaining ring 23 and away from the explosion-proof valve body 21, the explosion-proof valve body 21 being disposed in the mounting hole 11, the flange edge 22 being disposed on the first recessed platform 111, and welded to the assembly body.

[0034] The battery cell provided by this invention features an explosion-proof valve 2 with a flange 22 that protrudes from the plane of the explosion-proof valve body 21. The explosion-proof valve 2 is welded to the assembly body via the flange 22. Compared to direct welding of the explosion-proof valve body 21 to the assembly body, this effectively extends the heat conduction path during welding, preventing deformation and cracking of the explosion-proof valve 2 due to welding heat. This ensures the explosion-proof valve 2 can open under design pressure, guaranteeing the safety of the battery cell and battery pack. Furthermore, for battery cells with the electrolyte injection hole 7 located next to the explosion-proof valve 2, the retaining ring 23 prevents electrolyte contamination of the explosion-proof valve body 21 during electrolyte injection, ensuring the explosion-proof valve 2 is unaffected by the electrolyte and thus guaranteeing the safety performance of the battery cell.

[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 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, the mounting hole 11 having a first recessed platform 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 disposed 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 disposed in the mounting hole 11, the flange edge 22 is disposed on the first recessed platform 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] This configuration increases air insulation and improves the insulation effect on the explosion-proof valve body 21 because there is a heat insulation gap 113 between the retaining ring 23 and the inner wall of the mounting hole 11.

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

[0042] Specifically, if W1 is less than 0.3mm, that is, the width of the heat insulation gap 113 is too small, it is difficult to assemble the explosion-proof valve 2 with the cover plate 1, and the explosion-proof valve 2 is prone to deformation during assembly, which can easily cause scratches and damage to the explosion-proof valve 2. If W1 is greater than 10mm, that is, the width of the heat insulation gap 113 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.

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

[0044] like Figure 5 and Figure 6 As shown, flange edge 22 and the first recessed platform 111 are butt-welded. If W2 is less than 0.8mm, meaning the contact width between flange edge 22 and the first recessed platform 111 is too small, the contact width between the explosion-proof valve 2 and the cover plate 1 will also be small, making welding impossible. If W2 is greater than 4mm, meaning the contact width between flange edge 22 and the first recessed platform 111 is too large, the contact width between the explosion-proof valve 2 and the cover plate 1 will be large, making processing difficult and increasing the cost of the explosion-proof valve 2; therefore, its use is not recommended.

[0045] In some embodiments, the flange edge 22 and the first countersunk platen 111 are through-welded, and the contact width between the flange edge 22 and the first countersunk platen 111 is W3, where 1.5mm≤W3≤6mm.

[0046] like Figure 7 As shown, flange edge 22 and the first recessed platform 111 are penetrated and welded. If W3 is less than 1.5mm, the contact width between flange edge 22 and the first recessed platform 111 is too small, resulting in a small contact width between the explosion-proof valve 2 and the cover plate 1, making welding impossible. If W3 is greater than 6mm, the contact width between flange edge 22 and the first recessed platform 111 is too large, leading to a larger contact width between the explosion-proof valve 2 and the cover plate 1. This makes processing difficult, weakens the strength of the cover plate 1, and increases the material usage of the explosion-proof valve 2 due to the large contact area, thus increasing its cost. Therefore, its use is not recommended.

[0047] In some embodiments, the mating surface between the flange edge 22 and the first countersunk platform 111 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 first end face of the battery cell cover assembly along the X1 direction.

[0048] Specifically, the first end face of the cell cover assembly along the X1 direction refers to the end face furthest from the second end face of the cover plate 1 along the X1 direction. Further, the cell cover assembly also includes a terminal post 3 and a riveting block 6. The terminal post 3 is disposed on the cover plate 1 via the riveting block 6, and the first end face of the riveting block 6 is the second plane P2, as shown below. Figure 5 As shown, the first end face of the battery cell cover assembly along the X1 direction is the plane shown in 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 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.

[0050] Specifically, the flange edge 22 and the retaining ring 23 extend the heat conduction path. The longer the extension length of the flange edge 22 and the retaining ring 23, the longer the heat conduction path, and the better the heat insulation effect on the explosion-proof valve body 21. The width of the flange edge 22 (i.e., the length along the heat conduction direction) is limited for different welding methods, and here the length of the retaining ring 23 along the heat conduction direction is limited.

[0051] Positioning the explosion-proof valve body 21 between the first plane P1 and the second plane reduces the impact of welding heat on the valve body 21 during the welding assembly of the explosion-proof valve 2 and the cover plate 1. This ensures that the valve body 21 can open and release pressure under the designed pressure, guaranteeing the safety performance of the battery cell and battery pack, and preventing electrolyte contamination. Simultaneously, the explosion-proof valve body 21 does not extend beyond the first end face of the electrode post 3 along the X1 direction or the first end face of the riveting block 6 along the X1 direction, thus ensuring that it does not occupy space in the thickness direction of the battery cell cover plate 1.

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

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

[0054] By setting a second recessed platform 112 and controlling its depth D within the range of 0.1mm to 0.5mm, the weld formed by 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 avoiding the occupation of 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 internal battery space and hindering the improvement of battery volumetric energy density; its use is not recommended. When D is too large, the explosion-proof valve 2 may assemble normally, but the welding of the explosion-proof valve 2 to the cover plate 1, the cover plate 1, and the part of the cover plate supporting the explosion-proof valve 2 may deform; its use is not recommended.

[0055] In some embodiments, the pole post 3 includes a pole post body 31 and a pole post base plate 32 disposed at one end of the pole post body 31. The cover plate 1 is provided with a pole post assembly hole, the pole post body 31 is disposed in the pole post assembly hole and both ends pass through the pole post assembly hole, and the pole post base plate 32 is located on the second end face of the cover plate 1.

[0056] 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 the first end of the electrode post body 31 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, with one end connected to the electrode post body 31 and the other end used for conductive connection with the electrode group, so that the electrical energy inside the battery cell can be conducted to the electrode post body 31.

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

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

[0059] 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.

[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] In some embodiments, the device further includes a housing, an electrode assembly, and a cell cover assembly. The housing has an open end; the electrode assembly is disposed in a receiving cavity of the housing; the cell cover assembly is disposed at the open end of the housing and encapsulates the electrode assembly within the housing, and the assembly body is either the housing or the cell cover assembly.

[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 above 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. A battery cell, characterized in that, include: An 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 having a first recessed platform that is recessed from the second end face of the assembly body to the first end face of the assembly body. An 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 disposed on the outer wall of the retaining ring and away from the explosion-proof valve body. The explosion-proof valve body is disposed in the mounting hole, and the flange edge is disposed on the first countersunk platform and welded to the assembly body. There is a heat insulation gap between the retaining ring and the inner wall of the mounting hole; the width of the heat insulation gap is W1, 0.3mm≤W1≤10mm; The flange edge and the side wall of the first recessed platform are butt welded together, and the contact width between the flange edge and the first recessed platform is W2, 0.8mm≤W2≤4mm; or, the flange edge and the first recessed platform are through welded together, and the contact width between the flange edge and the first recessed platform is W3, 1.5mm≤W3≤6mm. 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°.

2. The battery cell according to claim 1, characterized in that, The mating surface between the flange edge and the first recessed platform is a first plane; the explosion-proof valve body is located between the first plane and the first end face of the assembly body along the X1 direction.

3. The battery cell according to claim 1, characterized in that, The mounting hole has a second recessed platform recessed from the second end of the assembly body toward the first recessed platform, and the depth of the second recessed platform is D, where 0mm < D ≤ 0.5mm.

4. The battery cell according to claim 1, characterized in that, Also includes: A housing having an open end; The electrode assembly is located in the receiving cavity of the housing; A cell cover assembly is disposed at the open end of the housing and encapsulates the electrode assembly within the housing; The assembly body is either the housing or the cell cover assembly.

5. A battery pack, characterized in that, Includes the battery cell according to any one of claims 1 to 4.

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