Battery cell casing, battery cell, and battery pack

Abstract

A battery cell casing, a battery cell, and a battery pack. The battery cell casing comprises a casing body, and the casing body comprises a first connecting edge and a second connecting edge, wherein the first connecting edge and the second connecting edge are joined, and an accommodating cavity is formed inside; and joining portions of the first connecting edge and the second connecting edge are welded to form a weld seam, the solder seam comprises a first boss that protrudes from an inner wall of the casing body, the height of the first boss that protrudes from the casing body towards the accommodating cavity is t1, the thickness of the casing body is t, and the height and the thickness satisfy ((t1+t) / t)≥1.08. In the battery cell casing, the strength of the weld seam is greater than the strength of the casing body, such that the pressure-bearing capability of the battery cell casing can be improved, thereby ensuring that the casing does not crack at the weld seam under the action of internal pressure. By means of increasing the requirements for the weld seam in the battery cell casing, the pressure resistance of the casing is improved, and the safety performance of the battery cell is improved, thereby reducing the risk of vehicle accidents caused by insufficient pressure resistance of the casing due to welding of the casing.

Description

Battery cell shell, battery cell and battery pack

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on December 7, 2023, with application number 202311670349.1 and invention name “Battery Cell Shell, Battery Cell and Battery Pack”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of battery technology, and in particular to battery cell casings, battery cells and battery packs. Background Art

[0004] The cell shell is the carrier of the cell. The cell shell and the cover together form a sealed cavity, which encapsulates the electrode group.

[0005] Currently, battery cell casings are primarily formed by bending or rolling, and then butt-welded on the sides. For example, in the case of a blade cell, the casing is rectangular in shape, butt-welded on one side to create a cell housing.

[0006] In the existing welding structure, the weld is a molten joint of the base material, which is weaker than the plate itself. When there is high-pressure gas inside the battery cell, the shell will burst at the weld, which cannot meet the requirement that the battery cell can withstand a certain pressure value and has poor safety. Summary of the Invention

[0007] In view of this, the present application provides a battery cell shell, a battery cell and a battery pack to solve the problems of low weld strength and poor battery safety in existing welding structures.

[0008] In the first aspect, the present application provides a battery cell shell, including a shell body, the shell body including a first connecting edge and a second connecting edge, the first connecting edge and the second connecting edge are spliced ​​together to form an accommodating cavity inside; the joint of the first connecting edge and the second connecting edge is welded to form a weld, the weld includes a first boss protruding from the inner wall of the shell body, the height of the first boss protruding from the shell body toward the accommodating cavity is t1, the thickness of the shell body is t, and the height of the first boss protruding from the shell body toward the accommodating cavity satisfies: ((t1+t) / t)≥1.08.

[0009] Beneficial Effects: The housing body is spliced ​​together between the first and second connecting edges to form an internal cavity for accommodating the electrode assembly of the battery cell. The first and second connecting edges are butt-welded, and the weld has a first boss that protrudes from the inner wall of the housing body. The height t1 of the first boss protruding from the housing body toward the cavity is greater than or equal to 0.08t. This ensures that the weld is stronger than the housing body, increasing the pressure-bearing capacity of the battery cell housing and ensuring that the weld does not crack under internal pressure.

[0010] In an optional embodiment, the height of the first boss protruding from the shell body toward the accommodating cavity also satisfies: t1≤0.8t.

[0011] Beneficial effect: The height of the first boss of the weld protruding from the shell body toward the accommodating cavity is controlled within the range of 0.08t to 0.8t, which can improve the strength of the weld and meet the battery cell requirement that the shell bursting pressure is not less than 1.2Mpa.

[0012] In an optional embodiment, the weld further includes a second boss protruding from the outer wall of the shell body.

[0013] Beneficial effect: By providing the second boss, and the second boss protruding from the outer wall of the shell body, the two surfaces of the weld are respectively higher than the inner wall and outer wall of the shell body, thereby further improving the strength of the weld and improving the pressure resistance of the battery cell shell.

[0014] In an optional embodiment, the height of the second boss protruding from the shell body in a direction away from the accommodating cavity is t2, 0mm≤t2≤0.08mm.

[0015] Beneficial effect: The height of the second boss protruding from the shell body toward the direction away from the accommodating cavity is controlled within the range of 0 to 0.08, ensuring that the weld strength is improved while not affecting the insulating film coated on the battery cell shell.

[0016] In an optional embodiment, the width of the weld is L, which is in the range of 0.5 mm ≤ L ≤ 3 mm.

[0017] Beneficial effect: The width of the weld is controlled within the range of 0.5mm to 3mm, which can meet the use requirements of the battery cell.

[0018] In an optional embodiment, the cross-section of the first boss and / or the second boss includes an approximate trapezoid, triangle or arc shape, and / or the width of the first boss and / or the second boss gradually decreases in a direction away from the shell body.

[0019] Beneficial effect: This arrangement allows for a smooth transition between the weld and the shell body, avoids obvious steps between the weld and the shell, and prevents damage to the battery cell when the battery cell pole is assembled into the battery cell shell.

[0020] In an optional embodiment, the bursting pressure of the battery cell shell is P, P≥1.2 MPa, and the thickness t of the shell body satisfies: 0.2 mm≤t≤3 mm.

[0021] Beneficial effect: The thickness of the shell body is controlled within the range of 0.3mm to 1.5mm, which can meet the design requirement that the bursting pressure of the battery cell shell is greater than or equal to 1.2Mpa.

[0022] In an optional embodiment, the battery cell shell includes two oppositely disposed large surfaces and two oppositely disposed side surfaces, and the weld is located on any side surface of the battery cell shell.

[0023] Beneficial effect: With this arrangement, when the battery cells are assembled into a battery module, the welds do not occupy the assembly space of the large surface of the battery cells.

[0024] In an optional embodiment, the thickness t of the shell body satisfies: 0.35 mm ≤ t ≤ 3 mm.

[0025] In a second aspect, the present application further provides a battery cell, comprising a unit and a battery cell shell according to any one of the above technical solutions; the electrode group is arranged in a receiving cavity of the battery cell shell.

[0026] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells and will not be described in detail here.

[0027] On the third aspect, the present application also provides a battery pack comprising battery cells in at least two or more technical solutions.

[0028] Beneficial effects: Since the battery pack includes battery cells, it has the same effects as the battery cells and will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the specific implementation methods or the description of the prior art. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0030] FIG1 is a schematic structural diagram of a battery cell housing according to an embodiment of the present application;

[0031] FIG2 is a top view of the battery cell housing shown in FIG1 ;

[0032] FIG3 is a cross-sectional view along AA in FIG2 ;

[0033] FIG4 is a schematic diagram of a partially enlarged structure of point B in FIG3 ;

[0034] Figure 5 is a schematic diagram of the structure of the battery cell shell bursting from the weld;

[0035] Figure 6 is a schematic diagram of the structure of the battery cell shell exploding from the large surface;

[0036] FIG7 is a schematic structural diagram of a battery cell according to an embodiment of the present application;

[0037] FIG8 is a metallographic image of the weld according to an embodiment of the present application.

[0038] Description of reference numerals:

[0039] 10. Battery cell shell; 1. Shell body; 101. First connecting edge; 102. Second connecting edge; 103. Large surface; 104. Side surface; 2. Weld; 201. First boss; 202. Second boss; 3. Accommodating cavity; 100. Battery cell; C. Explosion site. DETAILED DESCRIPTION

[0040] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of this application.

[0041] The following describes an embodiment of the present application in conjunction with Figures 1 to 8.

[0042] According to an embodiment of the present application, on the one hand, a battery cell shell 10 is provided, including a shell body 1, the shell body 1 including a first connecting edge 101 and a second connecting edge 102, the first connecting edge 101 and the second connecting edge 102 are spliced ​​together to form an accommodating cavity 3 inside; the splicing of the first connecting edge 101 and the second connecting edge 102 is welded to form a weld 2, the weld 2 includes a first boss 201 protruding from the inner wall of the shell body 1, the height of the first boss 201 protruding from the shell body 1 toward the accommodating cavity 3 is t1, the thickness of the shell body 1 is t, and the height of the first boss 201 protruding from the shell body 1 toward the accommodating cavity 3 satisfies: ((t1+t) / t)≥1.08.

[0043] The shell body 1 is joined by a first connecting edge 101 and a second connecting edge 102 to form an internal cavity 3 for accommodating the electrode assembly of the battery cell 100. The first connecting edge 101 and the second connecting edge 102 are butt-welded, and the weld 2 comprises a first boss 201. The weld 2 protrudes from the inner wall of the shell body 1, and the height t1 of the first boss 201 from the shell body 1 toward the cavity 3 is greater than or equal to 0.08t. This ensures that the strength of the weld 2 is greater than that of the shell body 1, increasing the pressure-bearing capacity of the battery cell shell 10 and ensuring that the weld 2 does not crack under internal pressure. By increasing the requirements for the weld 2 within the battery cell shell 10, the shell's pressure resistance is increased, improving the safety of the battery cell 100 and reducing the risk of vehicle accidents caused by insufficient shell pressure resistance due to shell welding.

[0044] In one embodiment, the height of the first boss 201 protruding from the housing body 1 toward the accommodating cavity 3 also satisfies: t1≤0.8t.

[0045] Controlling the height of the first protrusion 201 of the weld 2, which rises from the housing body 1 toward the accommodating cavity 3, within the range of 0.08t to 0.8t, improves the strength of the weld 2 and meets the battery cell 100's requirement for a housing burst pressure of no less than 1.2 MPa. The actual welding effect is shown in the metallographic image of the weld seam in Figure 8. From the perspective shown in Figure 8, the lower raised protrusion is the first protrusion 201.

[0046] In one embodiment, the weld 2 further includes a second boss 202 protruding from the outer wall of the shell body 1 .

[0047] By providing the second boss 202 and protruding from the outer wall of the shell body 1 , the two surfaces of the weld 2 are respectively higher than the inner wall and outer wall of the shell body 1 , thereby further improving the strength of the weld 2 and the pressure resistance of the battery cell shell 10 .

[0048] In one embodiment, the height of the second protrusion 202 protruding from the housing body 1 in a direction away from the accommodating cavity 3 is t2, and 0 mm ≤ t2 ≤ 0.08 mm.

[0049] The height of the second boss 202 protruding from the shell body 1 in the direction away from the accommodating cavity 3 is controlled within the range of 0 to 0.08, thereby improving the strength of the weld 2 while not affecting the insulating film covering the cell shell 10 .

[0050] In one embodiment, the width of the weld 2 is L, which is in the range of 0.5 mm ≤ L ≤ 3 mm.

[0051] When the width of the weld 2 is small, such as when the width of the weld 2 is less than 0.5 mm, the following disadvantages may occur: 1. The weld 2 is relatively sharp, and when the pole group of the battery cell 100 is inserted into the accommodating cavity 3 of the battery cell shell 10, it is easy to scratch the bare battery cell 100 insulating sheet that wraps the pole group, causing the risk of overlapping and short-circuiting the pole group of the battery cell 100 and the battery cell shell 10; 2. The sealing area of ​​the battery cell shell 10 is narrow, resulting in poor sealing and the risk of leakage.

[0052] When the width of the weld 2 is too large, such as when the width of the weld 2 is greater than 3 mm, the weight of the cell housing 10 will increase significantly, and the space of the accommodating cavity 3 inside the cell housing 10 will decrease, resulting in a decrease in the energy density of the cell 100 and an increase in cost.

[0053] Therefore, controlling the width of the weld 2 within the range of 0.5 mm to 3 mm can meet the use requirements of the battery cell 100 .

[0054] In one embodiment, the cross section of the first boss 201 and / or the second boss 202 includes an approximately trapezoidal, triangular, or arc-shaped shape, and / or the width of the first boss 201 and / or the second boss 202 gradually decreases in a direction away from the housing body 1 .

[0055] In one embodiment, the cross section of the first boss 201 is trapezoidal or triangular.

[0056] In one embodiment, the cross section of the second boss 202 is trapezoidal or triangular.

[0057] Among them, the cross-section of the first boss 201 is set to a trapezoid, and / or the cross-section of the second boss 202 is set to a trapezoid, so that a smooth transition is made between the weld 2 and the shell body 1, avoiding the appearance of obvious steps between the weld 2 and the shell, and preventing damage to the battery cell 100 when the battery cell 100 poles are assembled into the battery cell shell 10.

[0058] In one embodiment, the bursting pressure of the battery cell shell is P, P≥1.2 MPa, and the thickness t of the shell body 1 satisfies: 0.2 mm≤t≤3 mm.

[0059] Controlling the thickness of the shell body 1 within the range of 0.3 mm to 1.5 mm can ensure that the shell body 1 meets the design requirement that the bursting pressure of the battery cell shell is greater than or equal to 1.2 MPa.

[0060] In one embodiment, the cell housing 10 is a rectangular parallelepiped structure, and the cell housing 10 is connected and closed by a weld 2 .

[0061] The cell casing 10 is a rectangular parallelepiped structure suitable for blade batteries. After the casing body 1 of the cell casing 10 is bent, its two edges, a first connecting edge 101 and a second connecting edge 102, are joined and welded together to form a weld seam 2. This weld seam 2 connects and closes the cell casing 10, creating a cavity that accommodates the cell 100 while maintaining a reasonable weight.

[0062] In one embodiment, the battery cell casing 10 includes two oppositely disposed large surfaces 103 and two oppositely disposed side surfaces 104 , and the weld 2 is located on any one of the side surfaces 104 of the battery cell casing 10 .

[0063] When the battery cells 100 are assembled into a battery module, the large surfaces 103 of the battery cells 100 are usually spliced ​​adjacent to each other, and the weld seam 2 of the battery cell shell 10 is set on the side surface 104. In this way, when the battery cells 100 are assembled into a battery module, the weld seam 2 does not occupy the assembly space of the large surface 103 of the battery cells 100.

[0064] The following is a comparison table of experiments on the shell bursting pressure using welds 2 of different sizes.

[0065] The strength design of the battery cell shell must meet the following requirements: the bursting pressure is P, P≥1.2Mpa.

[0066] In one embodiment, the thickness t of the housing body 1 satisfies: 0.35 mm ≤ t ≤ 3 mm.

[0067] The following battery cell casings 10 have a casing body 1 thickness t of 0.35 mm. Seven experimental groups were set up, with six battery cell casings 10 in each experimental group, corresponding to the same type of weld 2 connection (except for the different values ​​of t1 and t2 of the weld 2, all other aspects are the same). Table 1 shows the experimental results of the measured casing burst pressure and tear location at different weld 2 heights inside the battery cell casing 10.

[0068] Table 1

[0069] Table 1 shows that for six different shell weld seam thicknesses, the blasting test data show that: when the height of the first boss 201 of the weld seam 2 ((t1+t) / t) ≥ 1.08, that is, t1 ≥ 0.028 mm, the maximum shell blasting pressure is greater than 1.2 MPa, meeting the design and use requirements of the battery cell 100. As shown in Figure 5, the blasting point C is the weld seam. When the height of the first boss 201 of the weld seam 2 reaches 0.05 mm, the battery cell shell 10 reaches its maximum blasting pressure, blasting from the large surface 103. As shown in Figure 6, the blasting point C is the large surface 103 of the shell. If the height of the first boss 201 of the weld seam 2 is further increased, the blasting still occurs from the large surface 103, so there is no need to further increase the height of the weld seam 2.

[0070] The following battery cell casings 10 have a casing body 1 thickness t of 0.4 mm. Seven experimental groups were set up, with six battery cell casings 10 in each experimental group, corresponding to the same type of weld 2 connection (except for the different values ​​of t1 and t2 of the weld 2, all other aspects are the same). Table 2 shows the experimental results of the measured casing burst pressure and tear location at different weld 2 heights inside the battery cell casing 10.

[0071] Table 2

[0072] It can be seen from Table 2 that for the blasting test data of six different thicknesses of the weld 2 in the shell, it can be seen that: when the protrusion height of the first boss 201 of the weld 2 ((t1+t) / t)≥1.08, that is, t1≥0.032mm, the maximum blasting pressure of the shell is greater than 1.2Mpa, which meets the design and use requirements of the battery cell 100. As shown in Figure 5, the explosion point C is the weld; when the protrusion height of the first boss 201 of the weld 2 reaches 0.065mm, the explosion of the battery cell shell 10 reaches the maximum and explodes from the large surface 103. As shown in Figure 6, the explosion point C is the large surface 103 of the shell; if the protrusion height of the first boss 201 of the weld 2 is continued to increase, it will still explode from the large surface 103, and there is no need to continue to increase the height of the weld 2.

[0073] The following battery cell casings 10 have a casing body 1 thickness t of 0.5 mm. Seven experimental groups were set up, with six battery cell casings 10 in each experimental group, corresponding to the same type of weld 2 connection (except for the different values ​​of t1 and t2 of the weld 2, all other aspects are the same). Table 3 shows the experimental results of the measured casing burst pressure and tear location at different weld 2 heights inside the battery cell casing 10.

[0074] Table 3

[0075] It can be seen from Table 3 that for the blasting test data of six different thicknesses of the weld 2 in the shell, it can be seen that: when the protrusion height of the first boss 201 of the weld 2 ((t1+t) / t)≥1.08, that is, t1≥0.04mm, the maximum blasting pressure of the shell is greater than 1.2Mpa, which meets the design and use requirements of the battery cell 100. As shown in Figure 5, the explosion point C is the weld; when the protrusion height of the first boss 201 of the weld 2 reaches 0.06mm, the explosion of the battery cell shell 10 reaches the maximum and explodes from the large surface 103. As shown in Figure 6, the explosion point C is the large surface 103 of the shell; if the protrusion height of the first boss 201 of the weld 2 is continued to increase, it will still explode from the large surface 103, and there is no need to continue to increase the height of the weld 2.

[0076] The following battery cell casings 10 have a casing body 1 thickness t of 0.55 mm. Seven experimental groups were set up, with six battery cell casings 10 in each experimental group, corresponding to the same type of weld 2 connection (except for the different values ​​of t1 and t2 of the weld 2, all other aspects are the same). Table 4 shows the experimental results of the measured casing burst pressure and tear location at different weld 2 heights inside the battery cell casing 10.

[0077] Table 4

[0078] It can be seen from Table 4 that for the blasting test data of six different thicknesses of the weld 2 in the shell, it can be seen that: when the protrusion height of the first boss 201 of the weld 2 ((t1+t) / t)≥1.08, that is, t1≥0.044mm, the maximum blasting pressure of the shell is greater than 1.2Mpa, which meets the design and use requirements of the battery cell 100. As shown in Figure 5, the explosion point C is the weld; when the protrusion height of the first boss 201 of the weld 2 reaches 0.055mm, the explosion of the battery cell shell 10 reaches the maximum and explodes from the large surface 103. As shown in Figure 6, the explosion point C is the large surface 103 of the shell; if the protrusion height of the first boss 201 of the weld 2 is continued to increase, it will still explode from the large surface 103, and there is no need to continue to increase the height of the weld 2.

[0079] The battery cell shell 10 provided in this embodiment has a long battery cell shell 10, such as a blade battery cell shell 10. Since the wall thickness of the shell body 1 is very thin, the shell welding increases a certain risk of cracking. Therefore, the thickness of the weld 2 is increased during welding to reduce the risk of shell welding to the battery cell 100. At the same time, considering the structural weight and space issues, a reasonable increase in welding strength can best improve the strength of the shell weld 2. Therefore, this patent design stipulates the height, width and other related dimensions of the weld 2.

[0080] According to an embodiment of the present application, in a second aspect, a battery cell 100 is further provided, comprising a unit and a battery cell housing 10 according to any one of the above technical solutions; the electrode group is arranged in the accommodating cavity 3 of the battery cell housing 10 .

[0081] Since the battery pack includes the battery cell 100 and has the same effect as the battery cell 100 , details thereof will not be repeated here.

[0082] According to an embodiment of the present application, in a third aspect, a battery pack is further provided, comprising at least two battery cells 100 in the above technical solutions.

[0083] Since the battery pack includes the battery cell 100 and has the same effect as the battery cell 100 , details thereof will not be repeated here.

[0084] Although the embodiments of the present application have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present application, and such modifications and variations shall fall within the scope defined by the appended claims.

Claims

1. A battery cell casing, characterized in that: It includes a shell body, the shell body includes a first connecting edge and a second connecting edge, the first connecting edge and the second connecting edge are spliced ​​together to form an accommodating cavity inside; the first connecting edge and the second connecting edge are welded at the splicing point to form a weld, the weld includes a first boss protruding from the inner wall of the shell body, the height of the first boss protruding from the shell body toward the accommodating cavity is t1, the thickness of the shell body is t, and the height of the first boss protruding from the shell body toward the accommodating cavity satisfies: ((t1+t) / t)≥1.

08.

2. The battery cell casing according to claim 1, characterized in that: The height of the first boss protruding from the shell body toward the accommodating cavity also satisfies: t1≤0.8t.

3. The battery cell casing according to claim 1 or 2, characterized in that: The weld also includes a second boss protruding from the outer wall of the shell body.

4. The battery cell casing according to claim 3, characterized in that: The height of the second boss protruding from the shell body in a direction away from the accommodating cavity is t2, 0mm≤t2≤0.08mm.

5. The battery cell casing according to claim 1 or 2, characterized in that: The width of the weld is L, which is in the range of 0.5 mm ≤ L ≤ 3 mm.

6. The battery cell casing according to claim 3, characterized in that: The cross section of the first boss and / or the second boss is approximately trapezoidal, triangular or arc-shaped, and / or the width of the first boss and / or the second boss gradually decreases in a direction away from the shell body.

7. The battery cell casing according to claim 1 or 2, characterized in that: The bursting pressure of the battery cell shell is P, P≥1.2Mpa, and the thickness t of the shell body satisfies: 0.2mm≤t≤3mm.

8. The battery cell casing according to claim 7, characterized in that: The battery cell shell includes two oppositely disposed large surfaces and two oppositely disposed side surfaces, and the welding seam is located on any of the side surfaces of the battery cell shell.

9. The battery cell casing according to any one of claims 1 to 8, characterized in that: The thickness t of the shell body satisfies: 0.35mm≤t≤3mm.

10. A battery cell, characterized in that: include: The battery cell casing according to any one of claims 1 to 9; The electrode group is arranged in the accommodating cavity of the battery cell shell.

11. A battery pack, characterized in that: Comprising at least two battery cells according to claim 10.

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