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 a shell which is provided with a pressure relief hole, and a positioning convex rib is further arranged on the shell, the positioning convex rib is arranged around the circumferential direction of the pressure relief hole, the positioning convex rib is protruded to the outside of the shell along the wall thickness direction of the shell, one side of the positioning convex rib which faces the inner cavity of the shell is formed as a groove, and a supporting part is formed on the shell in the region between the positioning convex rib and the pressure relief hole; a pressure relief valve is installed in the region surrounded by the positioning convex rib, the pressure relief valve comprises a main body part and a welding part, the welding part is connected around the outer circumferential side of the main body part, the welding part is overlapped on the supporting part and is welded with the positioning convex rib. The pressure relief valve is installed in the region surrounded by the positioning convex rib, and the supporting part provides support for the pressure relief valve, accurate positioning during the assembly of the pressure relief valve and the shell is realized, the positioning and assembling difficulty is reduced, the positioning convex rib is protruded to the outside of the shell as a reinforcing rib, the welding depth can be increased, and the welding strength can be increased.

Description

Technical Field

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

[0002] A battery cell mainly consists of a casing, cover plate assembly, and electrode assembly. During battery cell use, there is a risk of thermal runaway, during which a large amount of high-temperature fumes are generated inside the cell, posing a significant hazard. Battery cells are typically equipped with a pressure relief valve, which opens in the event of thermal runaway to release the high-temperature fumes inside the cell, ensuring proper venting and pressure relief during such events. The pressure relief valve can be located on the casing, which has through-holes; the valve is then installed within these through-holes to achieve proper assembly between the valve and the casing.

[0003] However, the housing in the prior art is usually thin, which makes it difficult to position and assemble the pressure relief valve and the housing, and the welding strength between the pressure relief valve and the housing is low, which in turn affects the safety of the pressure relief valve. Summary of the Invention

[0004] In view of this, the present invention provides a battery cell and a battery pack to solve the problems of difficult positioning and assembly between the pressure relief valve and the housing and low welding strength.

[0005] In a first aspect, the present invention provides a battery cell, comprising: a housing having a pressure relief hole, the housing also having a positioning rib arranged circumferentially around the pressure relief hole, the positioning rib protruding outward along the wall thickness direction of the housing, the side of the positioning rib facing the inner cavity of the housing being formed as a groove, and a support portion forming on the housing in the area between the positioning rib and the pressure relief hole; and a pressure relief valve installed in the area enclosed by the positioning rib, the pressure relief valve comprising a main body and a welding portion, the welding portion being connected to the outer periphery of the main body, the welding portion overlapping the support portion and being welded to the positioning rib.

[0006] Beneficial effects: By setting positioning ribs around the pressure relief hole on the housing, with the positioning ribs spaced apart from the pressure relief hole, and the area between the positioning ribs and the hole wall forming a support, the pressure relief valve is installed within the area enclosed by the positioning ribs, and the support provides support for the pressure relief valve. This achieves accurate positioning of the pressure relief valve during the assembly process with the housing, reducing the difficulty of positioning and assembly, and improving assembly efficiency. Furthermore, the positioning ribs, as reinforcing ribs, can strengthen the structural strength of the area around the pressure relief hole on the housing, improve the housing's resistance to deformation and its flatness, thereby improving the precision of the assembly between the pressure relief valve and the housing, and facilitating welding between the pressure relief valve and the housing. At the same time, the positioning ribs protrude outwards from the housing, so the welding depth between the positioning ribs and the welded part can be increased along the wall thickness direction of the housing, thereby increasing the welding strength, meeting welding requirements, and improving the safety of the pressure relief valve.

[0007] In one optional embodiment, the wall thickness of the sidewall of the housing is H; along the wall thickness direction of the sidewall on the housing where the pressure relief hole is provided, the protrusion height of the positioning rib is h; wherein, h and H satisfy the relationship: 0.5≤h / H≤2.

[0008] Beneficial effects: It can ensure that the positioning ribs can effectively strengthen the structural strength of the area around the pressure relief hole on the shell, thereby improving the shell's resistance to deformation. It can also ensure the flatness of the interface between the shell and the pressure relief valve, thereby meeting the precision assembly and welding requirements between the pressure relief valve and the shell, improving welding quality, and ensuring the safety of the battery cell.

[0009] In one optional embodiment, the positioning rib is annular, and the groove is an annular groove with a width of w, wherein w and h satisfy the relationship: 1≤w / h≤5.

[0010] Beneficial effects: It can ensure that the positioning rib itself has good structural strength, thereby effectively strengthening the structural strength of the area around the pressure relief hole on the shell, improving the shell's resistance to deformation, and ensuring the flatness of the interface between the shell and the pressure relief valve, thus meeting the requirements for precision assembly and welding quality between the pressure relief valve and the shell.

[0011] In one optional embodiment, the wall thickness H of the sidewall of the housing is in the range of 0.3 mm ≤ H ≤ 1 mm.

[0012] Beneficial effects: It can ensure the structural strength of the casing, the reliability and safety of the battery cell, and reduce the cost and weight of the casing, which is conducive to improving the energy density of the battery cell.

[0013] In one optional embodiment, along the wall thickness direction of the sidewall on the housing where the pressure relief hole is provided, the surface of the positioning rib facing away from the inner cavity of the housing is a first surface, and the surface of the welded part facing away from the housing is a second surface, with the first surface and the second surface being flush.

[0014] Beneficial effects: On the one hand, it is convenient to judge whether the pressure relief valve is installed in place by observing whether the first surface and the second surface are flush, thereby improving the assembly accuracy. On the other hand, it is convenient to weld between the welding part and the positioning rib, improving the welding efficiency, thereby improving the production efficiency of the battery cell production line.

[0015] In one alternative embodiment, the welded portion is welded to the positioning rib to form a weld mark on the welded portion and the positioning rib.

[0016] Along the wall thickness direction of the sidewall on the housing where the pressure relief hole is provided, the penetration depth of the solder mark is H0, wherein the value of H0 is in the range of 0.3 mm ≤ H0 ≤ 1.0 mm;

[0017] And / or, the first surface is annular, and along the width direction of the annulus formed by the first surface, the weld width is W0, wherein the value of W0 is in the range of 0.5 mm ≤ W0 ≤ 2.5 mm.

[0018] Beneficial effects: By limiting the penetration depth of the solder to between 0.3 mm and 1.0 mm, the welding strength can be guaranteed, thus ensuring the stability of the connection between the pressure relief valve and the housing. At the same time, the pressure relief valve can be prevented from being welded through, thereby improving the reliability of the pressure relief valve and the safety of the battery cell.

[0019] And / or, by limiting the weld width W0 of the weld to a range of 0.5 mm to 2.5 mm, the welding strength can be guaranteed, ensuring the reliability of the fixed connection between the pressure relief valve and the housing. This also avoids excessive damage to the welded part and the strength of the positioning ribs by the weld, further improving the reliability of the pressure relief valve and the housing, and avoiding energy waste and reducing production costs.

[0020] In one optional embodiment, the support portion is annular with a ring width of W1, and the welding portion is annular with a ring width of W2, wherein W1 and W2 satisfy the relationship: 0.5≤W1 / W2≤1.

[0021] Beneficial effects: It can satisfy the support function of the support part for the welding part of the pressure relief valve, ensure the relative stability between the pressure relief valve and the shell, ensure the smooth welding of the pressure relief valve and the shell, improve the product qualification rate, and avoid the support part affecting the exhaust area of ​​the pressure relief valve, ensuring that the support part will not block the scratches, thereby ensuring that the pressure relief valve can open in time when the air pressure inside the battery cell reaches a certain value, improving the safety of the battery cell.

[0022] In one alternative embodiment, the battery cell further includes a support plate disposed inside the housing, the support plate having a first vent corresponding to the pressure relief hole and a second vent corresponding to at least a portion of the groove.

[0023] Beneficial effects: By opening a first vent hole corresponding to the pressure relief hole and a second vent hole corresponding to the groove on the support plate, when thermal runaway occurs in the battery cell, the gas inside the battery cell can not only be discharged through the first vent channel formed by the first vent hole and the pressure relief hole, but also be discharged through the second vent channel formed by the second vent hole and the groove and then discharged from the pressure relief hole, thereby increasing the venting rate and further improving the safety of the battery cell.

[0024] In one optional embodiment, the number of the first exhaust holes is multiple, the number of the second exhaust holes is multiple, and the opening size of the first exhaust holes is larger than the opening size of the second exhaust holes;

[0025] And / or, along the wall thickness direction of the sidewall on the housing where the pressure relief hole is provided, the thickness of the support plate ranges from 0.3 mm to 1.0 mm.

[0026] Beneficial effects: Setting the opening size of the first vent hole to be larger than that of the second vent hole ensures that when the cell is depressurized, the gas is first quickly discharged through the first vent hole with the larger opening size, and the second vent hole further increases the amount of gas discharged, thereby improving the venting efficiency of the cell and meeting the depressurization requirements of the cell.

[0027] And / or, the thickness of the support plate along the Z direction is 0.3 mm to 1.0 mm. This ensures that the support plate has sufficient thickness and structural strength, and provides stable support between the electrode assembly and the shell. In the event of thermal runaway in the cell, this prevents the electrode assembly from moving with the gas and blocking the pressure relief hole, ensuring that the gas inside the cell can be discharged smoothly. It also avoids the support plate being too thick, which would increase cost and weight, and is beneficial to improving the energy density of the cell.

[0028] Secondly, the present invention also provides a battery pack, including the aforementioned battery cell. Since the battery pack includes the battery cell and has the same effect as the battery cell, it will not be described in detail here. Attached Figure Description

[0029] 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.

[0030] Figure 1 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention;

[0031] Figure 2 for Figure 1 The exploded view of the battery cell shown;

[0032] Figure 3 for Figure 1 A top view of the battery cell shown;

[0033] Figure 4 for Figure 3 A cross-sectional view along the AA direction;

[0034] Figure 5 for Figure 4 A magnified view of part B in the diagram;

[0035] Figure 6 This is a schematic diagram of the assembly structure of the housing and pressure relief valve according to an embodiment of the present invention;

[0036] Figure 7 for Figure 6 The diagram shows the positional relationship between the housing and the pressure relief valve before assembly.

[0037] Figure 8 for Figure 6 A top view of the assembly structure of the housing and pressure relief valve shown;

[0038] Figure 9 for Figure 8 A cross-sectional view along the DD direction;

[0039] Figure 10 for Figure 9 A magnified view of part of E in the diagram;

[0040] Figure 11 for Figure 10 A magnified view of part of F;

[0041] Figure 12 This is a schematic diagram of the structure of a pressure relief valve according to an embodiment of the present invention;

[0042] Figure 13 This is a schematic diagram of the structure of a support plate according to an embodiment of the present invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] 10. Housing; 101. Pressure relief hole; 102. Positioning rib; 1021. First surface; 103. Groove; 104. Support part; 11. First side wall; 12. Second side wall; 13. Third side wall; 14. Fourth side wall; 20. Pressure relief valve; 201. Main body; 2011. Score; 202. Welded part; 2021. Second surface; 30. Support plate; 301. First vent hole; 302. Second vent hole; 40. Weld mark; 51. Positive electrode cover plate; 52. Negative electrode cover plate; 60. Electrode assembly; 70. End plate; 80. Insulating film. Detailed Implementation

[0045] 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.

[0046] The battery cell is equipped with a pressure relief valve to meet the normal venting and pressure relief requirements in the event of thermal runaway. The pressure relief valve can generally be set on the housing 10 or the cover plate of the battery cell. In order not to affect the arrangement of the terminal posts, injection holes and other structures integrated on the cover plate, the pressure relief valve is usually set on the housing 10. However, the housing 10 is generally thin. How to accurately position and assemble the pressure relief valve with the housing, and ensure that the welding fixation between the pressure relief valve and the housing meets certain strength requirements, to achieve accurate venting and pressure relief of the battery is a particularly important issue in the development of battery technology.

[0047] The following is combined Figures 1 to 13 The following describes embodiments of the present invention.

[0048] According to an embodiment of the present invention, in one aspect, a battery cell is provided, comprising: a housing 10 and a pressure relief valve 20. The housing 10 has a pressure relief hole 101, and a positioning rib 102 is also formed on the housing 10. The positioning rib 102 is arranged circumferentially around the pressure relief hole 101, and the positioning rib 102 protrudes outward along the wall thickness direction of the housing 10. The side of the positioning rib 102 facing the inner cavity of the housing 10 is formed as a groove 103. A support portion 104 is formed on the housing 10 in the area between the positioning rib 102 and the pressure relief hole 101. The pressure relief valve 20 is installed in the area enclosed by the positioning rib 102. The pressure relief valve 20 includes a main body portion 201 and a welding portion 202. The welding portion 202 is connected to the outer periphery of the main body portion 201, and the welding portion 202 overlaps the support portion 104 and is welded to the positioning rib 102. The wall thickness direction of the housing 10 refers to the wall thickness direction of the side wall on the housing 10 where the pressure relief hole 101 is provided.

[0049] Using the battery cell of this embodiment, by providing positioning ribs 102 surrounding the pressure relief hole 101 on the housing 10, with the positioning ribs 102 spaced apart from the pressure relief hole 101, and the area between the positioning ribs 102 and the hole wall of the pressure relief hole 101 forming a support portion 104, the pressure relief valve 20 is installed in the area enclosed by the positioning ribs 102 and the support portion 104 provides support for the pressure relief valve 20. This achieves accurate positioning of the pressure relief valve 20 during the assembly process with the housing 10, reduces the difficulty of positioning assembly, and helps improve assembly efficiency. Furthermore, the positioning ribs 102... 02, as a reinforcing rib, can strengthen the structural strength of the area around the pressure relief hole 101 on the housing 10, improve the deformation resistance and flatness of the housing 10, thereby improving the precision of the assembly between the pressure relief valve 20 and the housing 10, and also facilitating the welding of the pressure relief valve 20 and the housing 10. At the same time, the positioning rib 102 protrudes to the outside of the housing 10, so the welding of the positioning rib 102 and the welding part 202 can increase the welding depth along the wall thickness direction of the housing 10, thereby increasing the welding strength, meeting the welding requirements, and improving the safety of the pressure relief valve 20.

[0050] It should be noted that the main body 201 of the pressure relief valve 20 has a notch 2011. The notch 2011 is arranged circumferentially around the pressure relief valve 20 and is concentric with the welded part 202. The thickness of the pressure relief valve 20 at the notch 2011 is reduced, and the structural strength is weakened relative to other positions. When thermal runaway occurs in the battery cell, the gas pressure inside the battery cell increases, and the pressure relief valve 20 breaks and opens at the notch 2011. The gas inside the battery cell is discharged through the pressure relief hole 101 and the opening of the pressure relief valve 20. In addition, the battery cell also includes an electrode group 60. After the outer side is wrapped with an insulating film 80, it is placed inside the housing 10. The support plate 30 is set between the insulating film 80 on the outside of the electrode group 60 and the inner wall of the housing 10. When the cell experiences thermal runaway, the temperature is high, and the insulating film 80 and the support plate 30 will melt to a certain extent. Then, the gas that enters the groove 103 through the second vent 302 will flow through the gap between the support plate 30 and the housing 10 to the pressure relief hole 101 and then be discharged from the cell. That is, the gas in the groove 103 that is vented through the second vent 302 can be smoothly discharged to the outside of the cell when the pressure relief valve 20 is opened.

[0051] It should be noted that the battery cell has two mutually perpendicular X, Y, and Z directions, as shown in the diagram. Figures 1 to 2 , Figures 6 to 7 The arrows in the diagram indicate the formation of an XYZ rectangular coordinate system. The shell 10 includes a first sidewall 11, a second sidewall 12, a third sidewall 13, and a fourth sidewall 14 connected end to end in sequence. The first sidewall 11 and the third sidewall 13 are arranged opposite each other along the Z direction, and the second sidewall 12 and the fourth sidewall 14 are arranged opposite each other along the Y direction. Preferably, the dimensions of the first sidewall 11 and the third sidewall 13 along the Y direction are smaller than the dimensions of the second sidewall 12 and the fourth sidewall 14 along the Z direction, that is, the first sidewall 11 and the third sidewall 13 are narrow surfaces on the shell 10.

[0052] In one embodiment, further combination Figure 6 and 7 As shown, the pressure relief hole 101 is located on the first sidewall 11, which can reduce the impact on the flatness of the sidewall of the housing 10. The sidewall with the pressure relief hole 101 refers to the first sidewall 11, and the wall thickness direction of the sidewall with the pressure relief hole 101 on the housing 10 refers to the wall thickness direction of the first sidewall 11, i.e., the Z direction. Of course, the pressure relief hole 101 can also be located on other sidewalls besides the first sidewall 11, with the wall thickness direction of the third sidewall 13 being the Z direction, and the wall thickness direction of the second sidewall 12 or the fourth sidewall 14 being the Y direction.

[0053] This embodiment uses the example of a pressure relief hole 101 being provided on the first side wall 11. The wall thickness direction of the side wall on the housing 10 where the pressure relief hole 101 is provided refers to the Z direction.

[0054] In one embodiment, the wall thickness of the sidewall of the housing 10 is H; along the wall thickness direction of the sidewall on the housing 10 where the pressure relief hole 101 is provided, the protrusion height of the positioning rib 102 is h; wherein, h and H satisfy the relationship: 0.5≤h / H≤2, and the units of h and H are both mm. It should be noted that the wall thickness of all four sidewalls of the housing 10 is H, the pressure relief hole 101 is provided on the first sidewall 11, and the positioning rib 102 protrudes outward of the housing 10 along the Z direction, and the protrusion height of the positioning rib 102 along the Z direction is h, that is, the distance along the Z direction between the surface of the positioning rib 102 on the side away from the inner cavity of the housing 10 and the outer surface of the first sidewall 11 on the side away from the inner cavity of the housing 10 is h. If h / H is less than 0.5, the protrusion height of the positioning rib 102 is too small, resulting in insufficient structural reinforcement of the housing 10 and insufficient resistance to deformation, making it prone to deformation after welding or during use. If h / H is greater than 2, the protrusion height of the positioning rib 102 is too large, leading to poor stability and failing to meet the flatness requirements of the interface between the housing 10 and the pressure relief valve 20, thus affecting the assembly accuracy and welding effect of the pressure relief valve 20 and the housing 10. It should be noted that the flatness of the interface between the housing 10 and the pressure relief valve 20 refers to the flatness of the first surface 1021 of the positioning rib 102 facing the outside of the housing 10 and the second surface 2021 of the welded part 202 facing the outside of the housing 10.

[0055] Therefore, by limiting the value of h / H to the range of 0.5 to 2, it can be ensured that the positioning rib 102 can effectively strengthen the structural strength of the area around the pressure relief hole 101 on the housing 10, thereby improving the deformation resistance of the housing 10. It can also ensure the flatness of the interface between the housing 10 and the pressure relief valve 20, thereby meeting the precision assembly and welding requirements between the pressure relief valve 20 and the housing 10, improving the welding quality, and ensuring the safety of the battery cell.

[0056] Optionally, the value of h / H is any one of 0.5, 0.7, 0.8, 1, 1.2, 1.5, 1.8, 2 or a value between any two values.

[0057] In one embodiment, the positioning rib 102 is formed by bending a portion of the housing 10 located around the pressure relief hole 101. The forming method is simple and easy to form, and it can effectively strengthen the structural strength of the housing 10. The wall thickness at the positioning rib 102 is equal to the wall thickness of the side wall of the housing 10, both being H.

[0058] In one embodiment, the positioning rib 102 is annular, and the groove 103 is an annular groove with a width of w, where w and h satisfy the relationship: 1≤w / h≤5, and the units of w and h are both mm. It should be noted that the orthographic projection of the positioning rib 102 along the Z direction on the plane containing the outer surface of the first sidewall 11 is annular, denoted as the first annular ring. On the plane containing the outer surface of the first sidewall 11, the inner ring of the first annular ring is spaced apart from the wall of the pressure relief hole 101, and the spaced area forms the support portion 104. The positioning rib 102 is a convex ring surrounding the pressure relief hole 101, and the groove 103 is correspondingly provided with the positioning rib 102. The size of the annular width of the groove 103 directly reflects the size of the annular width formed by the orthographic projection of the positioning rib 102 on the outer surface of the first sidewall 11. If w / h is less than 1, the circumferential width of the groove 103 is too small relative to the protrusion height of the positioning rib 102. Consequently, the positioning rib 102 is narrow and tall, resulting in poor structural strength. This fails to effectively enhance the structural strength of the housing 10, leading to poor deformation resistance. Furthermore, it cannot meet the flatness requirements of the interface between the housing 10 and the pressure relief valve 20, affecting the assembly accuracy and welding effect of the pressure relief valve 20 and the housing 10. If w / h is greater than 5, the circumferential width of the groove 103 is too large relative to the protrusion height of the positioning rib 102. This results in a flat shape, which also does not significantly enhance the structural strength of the housing 10, leading to poor deformation resistance.

[0059] Therefore, by limiting w / h to a value within the range of 1 to 5, it is possible to ensure that the positioning rib 102 itself has good structural strength, thereby effectively strengthening the structural strength of the area surrounding the pressure relief hole 101 on the housing 10, improving the deformation resistance of the housing 10, and ensuring the flatness of the interface between the housing 10 and the pressure relief valve 20, thus meeting the requirements for precision assembly and welding quality between the pressure relief valve 20 and the housing 10.

[0060] Optionally, the w / h value can be any one of 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, or 5, or a value between any two of them.

[0061] In one embodiment, the wall thickness H of the sidewall of the housing 10 is in the range of 0.3 mm ≤ H ≤ 1 mm. If H is less than 0.3 mm, the wall thickness of the sidewall of the housing 10 is too small, resulting in poor structural strength of the housing 10, making it prone to deformation and reducing the reliability and safety performance of the battery cell. If H is greater than 1 mm, the wall thickness of the housing 10 is too large, leading to excessive weight and cost, and hindering the reduction of the battery cell's energy density. Therefore, by limiting H to a value between 0.3 mm and 1 mm, the structural strength of the housing 10, the reliability and safety of the battery cell can be guaranteed, while the cost and weight of the housing 10 can be reduced, which is beneficial for improving the energy density of the battery cell.

[0062] Optionally, H can be any value among 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1 mm, or a value between any two of these values.

[0063] In one embodiment, further combination Figures 10 to 11 As shown, along the wall thickness direction of the sidewall on the housing 10 where the pressure relief hole 101 is provided, the surface of the positioning rib 102 facing away from the inner cavity of the housing 10 is the first surface 1021, and the surface of the welded part 202 facing away from the housing 10 is the second surface 2021. The first surface 1021 and the second surface 2021 are flush. It should be noted that since the pressure relief hole 101 is provided on the first sidewall 11 of the housing 10, the surface of the positioning rib 102 facing away from the inner cavity of the housing 10 along the Z direction is the first surface 1021, and the surface of the welded part 202 facing away from the housing 10 along the Z direction is the second surface 2021. Here, the Z direction refers to... Figures 10 to 11 The direction indicated by the middle arrow is "Z". The first surface 1021 is the outer surface of the positioning rib 102, and the second surface 2021 is the surface of the welding part 202 facing the outside of the housing 10. By setting the first surface 1021 and the second surface 2021 to be flush, it is convenient to judge whether the pressure relief valve 20 is installed in place by observing whether the first surface 1021 and the second surface 2021 are flush, thereby improving the assembly accuracy. On the other hand, it is convenient to weld the welding part 202 and the positioning rib 102, thereby improving the welding efficiency and thus improving the production efficiency of the battery cell production line.

[0064] It should be noted that the pressure relief valve 20 includes a main body 201 and a welding part 202. The thickness of the main body 201 along the Z direction is less than the thickness of the welding part 202 along the Z direction. The welding part 202 has a larger thickness, which can prevent the pressure relief valve 20 from being welded through when it is welded to the housing 10, thereby improving the welding quality.

[0065] In one embodiment, the welding portion 202 is butt-welded to the positioning rib 102 to form a weld mark 40 on the welding portion 202 and the positioning rib 102; further combined Figure 11 As shown, along the wall thickness direction of the side wall on the housing 10 where the pressure relief hole 101 is provided, the penetration depth of the weld 40 is H0, where the value of H0 ranges from 0.3 mm to 1.0 mm. It should be noted that the outer peripheral wall of the welded part 202 and the outer wall of the inner ring of the positioning rib 102 are positioned opposite each other, with a small gap between them. This facilitates the butt welding operation and results in a good welding effect. During the welding process, the welding equipment welds along the Z-direction from the outside of the housing 10 to the inside of the housing 10. The welding trajectory is the joint gap between the welded part 202 and the positioning rib 102. The welded part 202 and the positioning rib 102 are fixedly connected by the weld 40. The penetration depth of the weld 40 refers to the depth of the weld 40 along the Z-direction. If H0 is less than 0.3 mm, the penetration depth of the solder 40 is too small, the welding strength is insufficient, and the connection between the pressure relief valve 20 and the housing 10 is not stable. This may cause the pressure relief valve 20 to fall off the housing 10 during normal use of the battery cell or when the internal air pressure of the battery cell does not reach the opening condition of the pressure relief valve 20, which is quite dangerous. If H0 is greater than 1.0 mm, the penetration depth of the solder 40 is too large, which may burn through the pressure relief valve 20, thereby damaging the structure of the pressure relief valve 20 and causing the pressure relief valve 20 to open abnormally.

[0066] Therefore, by limiting the penetration depth of the solder 40 to between 0.3 mm and 1.0 mm, the welding strength can be guaranteed, thus ensuring the stability of the connection between the pressure relief valve 20 and the housing 10, while also preventing the pressure relief valve 20 from being welded through, thereby improving the reliability of the pressure relief valve 20 and the safety of the battery cell.

[0067] It should be noted that after the pressure relief valve 20 is assembled with the housing 10, they are welded together as a single structure by laser welding, which can reduce the risk of pressure relief valves being easily welded through by penetration welding, which is common in the industry.

[0068] Optionally, H0 can be any value among 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm, or a value between any two of these values.

[0069] In one embodiment, the first surface 1021 is annular. Along the width of the annulus formed by the first surface 1021, the weld width of the weld 40 is W0, where the value of W0 ranges from 0.5 mm to 2.5 mm. If W0 is less than 0.5 mm, the weld width of the weld 40 is too narrow, resulting in insufficient welding strength and an inability to effectively fix the pressure relief valve 20 to the housing 10. If W0 is greater than 2.5 mm, the weld width of the weld 40 is too wide, excessively occupying space on the welded part 202 and the positioning rib 102, excessively weakening the strength of the welded part 202 and the positioning rib 102, increasing the risk of failure of the pressure relief valve 20 or the housing 10, and requiring excessive welding energy, resulting in energy waste and increased cost. Therefore, by limiting the weld width W0 of the weld mark 40 to a value within the range of 0.5 mm to 2.5 mm, the welding strength can be guaranteed, ensuring the reliability of the fixed connection between the pressure relief valve 20 and the housing 10. At the same time, the weld mark 40 can be prevented from excessively damaging the strength of the welded part 202 and the positioning rib 102 itself, further improving the reliability of the pressure relief valve 20 and the housing 10, and avoiding energy waste and reducing production costs.

[0070] Optionally, the value of W0 is any one of 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.7 mm, 2 mm, 2.3 mm, 2.5 mm, or a value between any two of these values.

[0071] In one embodiment, further combination Figure 11 As shown, the support part 104 is annular and the ring width of the support part 104 is W1, the welding part 202 is annular and the ring width of the welding part 202 is W2, wherein W1 and W2 satisfy the relationship: 0.5≤W1 / W2≤1. It should be noted that the support part 104 provides support for the welding part 202. If W1 / W2 is less than 0.5, the circumferential width of the support part 104 is too small relative to the circumferential width of the welding part 202. The support part 104 provides insufficient support for the welding part 202, which may cause the support part 104 to collapse into the housing 10 during assembly, resulting in the pressure relief valve 20 falling into the housing 10. This will affect the welding of the pressure relief valve 20 to the housing 10 and cause the product to be unqualified. If W1 / W2 is greater than 1, the circumferential width of the support part 104 is too large relative to the circumferential width of the welding part 202. The support part 104 exceeds the range of the welding part 202, and the support part 104 may even block the engraving 2011 on the pressure relief valve 20, affecting the exhaust area of ​​the pressure relief valve 20 and even affecting the smooth opening of the pressure relief valve 20.

[0072] Therefore, by limiting the ratio W1 / W2 between the annular width W1 of the support part 104 and the annular width W2 of the welding part 202 to a value between 0.5 and 1, the support part 104 can satisfy the supporting function of the welding part 202 of the pressure relief valve 20, ensuring the relative stability between the pressure relief valve 20 and the housing 10, ensuring the smooth welding of the pressure relief valve 20 and the housing 10, and improving the product qualification rate. At the same time, the support part 104 can avoid affecting the exhaust area of ​​the pressure relief valve 20, ensuring that the support part 104 will not block the engraving mark 2011, thereby ensuring that the pressure relief valve 20 can open in time when the gas pressure inside the battery cell reaches a certain value, improving the safety of the battery cell.

[0073] Optionally, the value of W1 / W2 is any one of 0.5, 0.6, 0.7, 0.8, 0.9, 1, or a value between any two values.

[0074] In other embodiments, along the annular width direction of the welding portion 202, the annular width formed between the outer ring of the welding portion 202 and the notch 2011 is W3. Alternatively, W3 can be set to satisfy the relationship W2 < W1 ≤ W3 with the annular width W1 of the support portion 104 and the annular width W2 of the welding portion 202. This ensures that the support portion 104 provides effective support for the welding portion 202, while also ensuring that the support portion 104 does not obstruct the exhaust area of ​​the pressure relief valve 20, thereby ensuring the timely opening of the pressure relief valve 20 and the smooth discharge of gas inside the battery cell, thus improving the safety of the battery cell.

[0075] In one embodiment, the circumferential width W2 of the welding part 202 is in the range of 0.5 mm ≤ W2 ≤ 2 mm. If W2 is less than 0.5 mm, the circumferential width of the welding part 202 is too small, resulting in poor structural stability, poor support stability on the support part 104, insufficient welding space for the weld mark 40 when welding with the housing 10, insufficient weld strength after welding, and poor reliability of the connection between the pressure relief valve 20 and the housing 10. If W2 is greater than 2 mm, the circumferential width of the welding part 202 is too large, wasting material, increasing weight, and hindering the improvement of the cell's energy density. Therefore, by limiting W2 to a value between 0.5 mm and 2 mm, the welding part 202 has a reasonable width dimension, which can ensure its own structural strength, thereby ensuring the stable support of the welding part 202 on the support part 104, and ensuring the weld strength after welding with the housing 10, ensuring the stability of the fixed connection between the pressure relief valve 20 and the housing 10, while avoiding material waste, controlling the weight of the pressure relief valve 20, and improving the energy density of the cell.

[0076] Optionally, the value of W2 is any one of 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2 mm, or a value between any two of these values.

[0077] In one embodiment, the battery cell further includes a support plate 30 disposed inside the housing 10. The support plate 30 has a first vent 301 corresponding to the pressure relief hole 101 and a second vent 302 corresponding to at least a portion of the groove 103. By providing the first vent 301 corresponding to the pressure relief hole 101 and the second vent 302 corresponding to the groove 103 on the support plate 30, when thermal runaway occurs in the battery cell, the gas inside the battery cell can not only be discharged through the first vent channel formed by the first vent 301 and the pressure relief hole 101, but also through the second vent 302 and the second vent channel formed by the groove 103 and then discharged from the pressure relief hole 101, thereby increasing the venting rate and further improving the safety of the battery cell.

[0078] In one embodiment, further combination Figure 2 and Figure 13 As shown, there are multiple first vent holes 301 and multiple second vent holes 302, and the opening size of the first vent holes 301 is larger than the opening size of the second vent holes 302. It should be noted that the first vent holes 301 are correspondingly arranged with the pressure relief hole 101, and the gas inside the cell is discharged to the pressure relief hole 101 through the first vent holes 301. The second vent holes 302 are correspondingly arranged with the groove 103, and the gas inside the cell is discharged to the groove 103 through the second vent holes 302 and then flows to the pressure relief hole 101. The groove width of the groove 103 is smaller than the opening area of ​​the pressure relief hole 101. Therefore, setting the opening size of the first vent holes 301 to be larger than the opening size of the second vent holes 302 ensures that when the cell is depressurized, the gas is first quickly discharged through the larger opening size of the first vent holes 301, and the second vent holes 302 further increase the amount of gas discharged, further improving the venting efficiency of the cell and meeting the pressure relief requirements of the cell.

[0079] It should be noted that if there is only one first vent hole 301 or one second vent hole 302, the opening area of ​​a single vent hole will be too large, affecting the structural strength of the support plate 30. Therefore, by setting multiple first vent holes 301 and setting multiple second vent holes 302 and setting multiple second vent holes 302, it is possible to ensure that all vent holes have sufficient total venting area and improve the structural stability of the support plate 30.

[0080] In this application, "multiple" means two or more (including two).

[0081] In one embodiment, the pressure relief hole 101 is racetrack shaped, and the size of the pressure relief hole 101 along the X direction is larger than its size along the Y direction. A plurality of first exhaust holes 301 are spaced apart along the X direction (i.e., the length direction of the support plate 30) to correspond to the pressure relief hole 101, so as to ensure that gas can be uniformly supplied to the pressure relief hole 101.

[0082] In one embodiment, the second vent holes 302 are provided in two rows. The first vent holes 301 are provided with a row of second vent holes 302 on each side along the Y direction. Each row of second vent holes 302 has a plurality of second vent holes 302 spaced apart along the X direction. Each row of second vent holes 302 corresponds to a part of the groove 103. This can not only ensure the smooth exhaust of the second vent holes 302, but also improve the symmetry of the support plate 30 structure, facilitate processing, and help improve the stability of the support plate 30.

[0083] In one embodiment, the thickness of the support plate 30 along the wall thickness direction of the sidewall on the housing 10 where the pressure relief hole 101 is provided is in the range of 0.3 mm to 1.0 mm. It should be noted that the pressure relief hole 101 is located on the first sidewall 11, and the thickness of the support plate 30 along the Z direction is 0.3 mm to 1.0 mm. This ensures that the support plate 30 has sufficient thickness and structural strength to provide stable support between the electrode assembly 60 and the housing 10. This prevents the electrode assembly 60 from blocking the pressure relief hole 101 when thermal runaway occurs in the battery cell, ensuring that the gas inside the battery cell can be smoothly discharged. Furthermore, it avoids excessive thickness of the support plate 30, which would increase cost and weight, and is beneficial for improving the energy density of the battery cell.

[0084] Optionally, the thickness of the support plate 30 may be any one of 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, or 1.0 mm, or a value between any two of these values.

[0085] Optionally, the support plate 30 can be made of materials such as PP (Polypropylene), PC (Polycarbonate), or PET (Polyethylene Terephthalate), and can be formed using processes such as injection molding or die cutting.

[0086] In one embodiment, the battery cell further includes a cover plate disposed at the open end of the housing 10 to close the housing 10. Optionally, the housing 10 has openings at both ends, and the cover plate includes a positive electrode cover plate 51 and a negative electrode cover plate 52, each of which closes one open end of the housing 10.

[0087] In one embodiment, the battery cell further includes an end plate 70, which is disposed on the side of the positive electrode cover plate 51 facing the inner cavity of the housing 10. The end plate 70 is supported between the positive electrode cover plate 51 and the electrode group 60 to prevent the electrode group 60 from moving inside the housing 10 and to improve stability.

[0088] In this embodiment, the battery cell can improve the deformation resistance of the interface between the housing 10 and the pressure relief valve 20 by providing positioning ribs 102 at intervals on the outer periphery of the pressure relief hole 101. This can meet the flatness requirements of the interface between the housing 10 and the pressure relief valve 20 and satisfy the requirements of precision assembly and welding.

[0089] It should be noted that the electrode assembly in a battery cell includes a positive electrode, a negative electrode, and a separator. During the charging and discharging process, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrode plates. The separator, positioned between the positive and negative electrode plates, prevents short circuits between the positive and negative electrodes while allowing active ions to pass through. The battery cell also includes an electrolyte, which conducts ions between the positive and negative electrodes. The electrode assembly has tabs that allow current to be drawn out. These tabs include positive and negative tabs. A positive and negative terminal are located on the cover plate, and the positive and negative tabs are electrically connected to the positive and negative terminals, respectively.

[0090] According to an embodiment of the present invention, in another aspect, a battery pack is also provided, comprising: the aforementioned battery cells. The battery pack further comprises a housing, in which the battery cells are disposed.

[0091] Specifically, the number of battery cells is multiple. Optionally, the battery cells are lithium-ion cells.

[0092] The following examples and comparative examples verify the influence of different parameter values ​​on the performance of the battery cell. Specifically, the flatness S of the casing and the amount of deformation change s are tested. The test results of the examples and comparative examples are shown in Table 1.

[0093] The shell flatness S refers to the flatness of the surface of the positioning rib 102 facing away from the inner cavity of the shell 10, that is, the flatness of the first surface 1021. The first surface 1021 corresponds to the welding surface of the welding part 202 of the pressure relief valve 20 (i.e., the second surface 2021). The shell flatness S is required to be less than or equal to 0.25 mm. If the flatness is higher than 0.25 mm, it will affect the welding effect at the mating point between the pressure relief valve 20 and the shell 10.

[0094] Among them, the deformation change amount s refers to the deformation change amount of the first surface 1021 of the battery cell housing 10 after the breathing test. It is required that after the pressure relief valve is welded to the housing, it can withstand more than 3000 breathing tests without deformation under the air pressure of ±0.3 Mpa. The specific test is as follows: After the pressure relief valve is welded to the housing, the two ends of the housing are sealed with a tooling, and ±0.3 Mpa positive and negative air pressures are input into the housing to simulate the internal air pressure state during the normal use of the battery. After 3000 cycles, record the deformation change amount of the first surface 1021 of the housing 10. If the change amount is less than 0.4 mm, it is qualified.

[0095] Table 1

[0096]

[0097] As can be seen from Table 1, for the battery cells of Embodiment 1 to Embodiment 12, the ratio h / H between the protrusion height h of the positioning rib 102 and the wall thickness H of the side wall of the housing 10, and the ratio w / h between the ring width w of the annular groove and the protrusion height h of the positioning rib 102 are both within the ranges of 0.5 ≤ h / H ≤ 2 and 1 ≤ w / h ≤ 5 defined in the present application. The test results show that the housing flatness S is all less than 0.25 mm, and the deformation change amount s of the housing is all less than 0.4 mm. The test conclusion is OK (that is, the test passes), and the performance of the housing 10 and the battery cell is good.

[0098] For the battery cells of Comparative Example 1 to Comparative Example 3, h / H is less than 0.5 and w / h is greater than 5, both of which are not within the ranges defined in the present application. Although the housing flatness S meets the requirements, the deformation change amount s of the housing is all greater than 0.4 mm, which does not meet the requirements. The test conclusion is NG (that is, the test fails). After the breathing test, the housing is severely deformed, and the anti-deformation ability is poor, and the safety performance of the housing is poor; for the battery cells of Comparative Example 4 to Comparative Example 6, h / H is greater than 2 and w / h is less than 0.5, both of which are not within the ranges defined in the present application. The housing flatness S is all greater than 0.25 mm, which does not meet the flatness requirements, and the deformation change amount s of the housing is all greater than 0.4 mm, which also does not meet the requirements. The test conclusion is NG. The housing 10 cannot meet the precise assembly and welding requirements with the pressure relief valve 20, and the anti-deformation ability is poor.

[0099] In summary, when h / H takes values within the range of 0.5 to 2 defined in the present application and w / h takes values within the range of 1 to 5 defined in the present application, it can not only meet the flatness requirements of the mating interface between the housing 10 and the pressure relief valve 20, so as to meet the precise assembly and welding requirements, but also improve the anti-deformation ability of the mating interface between the housing and the pressure relief valve, and improve the safety and service life of the battery cell.

[0100] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using commonly used testing methods in the art. For example, flatness can be measured using the knife-edge ruler method, flatness testing fixtures, or machine vision inspection methods. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0101] 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 an electric cell. The shell is provided with a relief hole, and a positioning protrusion is arranged on the shell and surrounds the relief hole; the positioning protrusion protrudes outward along the wall thickness direction of the shell; the positioning protrusion is bent from the part of the shell located at the periphery of the relief hole; the side of the positioning protrusion facing the inner cavity of the shell is provided with a groove; and the part of the shell between the positioning protrusion and the relief hole forms a support part. A relief valve is arranged in the area surrounded by the positioning protrusion; the relief valve comprises a main body part and a welding part; the welding part is connected to the outer periphery of the main body part; the welding part is overlapped on the support part and is welded with the positioning protrusion. The wall thickness of the side wall of the shell is H; the protruding height of the positioning protrusion along the wall thickness direction of the side wall of the shell is h; and the relationship between h and H satisfies the formula: 0.5<=h / H<=2. The positioning protrusion is annular, and the groove is an annular groove; the annular groove has a ring width w; and the relationship between w and h satisfies the formula: 1<=w / h<=5. The wall thickness H of the side wall of the shell ranges from 0.3 mm to 1 mm. The support part is annular, and the ring width of the support part is W1; the welding part is annular, and the ring width of the welding part is W2; and the relationship between W1 and W2 satisfies the formula: 0.5<=W1 / W2<=1.

2. The electric cell of claim 1, wherein, The surface of the side of the positioning protrusion facing away from the inner cavity of the shell is a first surface, and the surface of the side of the welding part facing away from the shell is a second surface; and the first surface is flush with the second surface.

3. The electric cell of claim 2, wherein, The welding part and the positioning protrusion are butt-welded to form a welding mark on the welding part and the positioning protrusion. The penetration depth of the welding mark along the wall thickness direction of the side wall of the shell ranges from 0.3 mm to 1.0 mm. The first surface is annular, and the fusion width of the welding mark along the ring width direction of the annular first surface ranges from 0.5 mm to 2.5 mm.

4. The electric cell of any one of claims 1 to 3, wherein, The electric cell further comprises a support plate arranged in the inner part of the shell; the support plate is provided with a first exhaust hole corresponding to the relief hole and a second exhaust hole corresponding to at least part of the groove.

5. The electric cell of claim 4, wherein, The number of the first exhaust holes is plural, the number of the second exhaust holes is plural, and the opening size of the first exhaust hole is larger than that of the second exhaust hole. The thickness of the support plate ranges from 0.3 mm to 1.0 mm.

6. A battery pack, characterized by, The application further relates to an electric cell. The electric cell comprises the electric cell according to any one of claims 1 to 5.

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