Housing and battery cell

Abstract

The application relates to the technical field of batteries and discloses a shell and a battery cell. The shell comprises a shell bottom wall and a plurality of shell side walls, the shell side walls are connected to one side of the shell bottom wall along the Z direction, and the shell bottom wall and the plurality of shell side walls enclose a containing cavity. The shell bottom wall is provided with a pressure relief hole and a boss, the boss is arranged at intervals with the pressure relief hole along the X direction, and the boss protrudes from one side of the shell bottom wall away from the containing cavity along the Z direction. The pressure relief hole is arranged on the shell bottom wall, and the boss is arranged at intervals with the pressure relief hole on the shell bottom wall, so that a concave-convex combined reinforcing structure is formed at the bottom of the shell, the structural strength of the shell bottom wall can be effectively improved without increasing the thickness of the shell, the shell bottom wall is prevented from being deformed after a pressure relief valve is welded and installed in the pressure relief hole, the planeness of the area on the shell bottom wall around the pressure relief valve is improved, the installation and welding reliability of the pressure relief valve on the shell bottom wall is ensured, the fatigue strength of the shell bottom wall and the pressure relief valve is improved, and the safety of the battery cell is ensured.

Description

Technical Field

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

[0002] The battery cell mainly consists of a housing, a cover plate assembly covering the opening of the housing, and electrode groups disposed within the inner cavity of the housing. The cover plate assembly includes a cover plate body and electrode post structures disposed thereon. A pressure relief valve is provided on the cover plate assembly or the housing. This valve opens to release pressure when the internal air pressure of the battery cell exceeds a preset value, thereby improving the safety of the battery cell. Existing battery cells, by placing the electrode post structures on the cover plate body and the pressure relief valve on the bottom of the housing away from the cover plate assembly, can achieve thermoelectric separation in the event of thermal runaway, avoiding secondary contact between the ejected electrolyte and electrode fragments with the electrode post structures.

[0003] However, since the bottom of the casing is generally relatively thin and the casing wall thickness is generally lower than the thickness of the cover plate body, the strength of the pressure relief valve after welding at the bottom of the casing is relatively weak and it is easy to deform. This results in poor fatigue strength of the pressure relief valve, which is not conducive to ensuring the safety of the battery cell. Summary of the Invention

[0004] This invention provides a housing and a battery cell to solve the problem of weak strength after the pressure relief valve is welded to the bottom of the housing.

[0005] In a first aspect, the present invention provides a housing, comprising: a bottom wall and a plurality of side walls, wherein the side walls are connected to one side of the bottom wall along the Z direction, and the bottom wall and the plurality of side walls enclose a receiving cavity; the bottom wall is provided with a pressure relief hole and a boss, the boss and the pressure relief hole are spaced apart along the X direction, the bottom wall has a first surface away from the receiving cavity along the Z direction, and the boss protrudes from the first surface along the Z direction.

[0006] Beneficial effects: By setting the pressure relief hole on the bottom wall of the housing and setting the boss on the bottom wall of the housing at intervals with the pressure relief hole, the setting of the boss changes the structural shape of the bottom of the housing, so that the bottom of the housing forms a reinforced structure with concave and convex parts. Compared with the traditional flat housing wall, it can effectively improve the structural strength of the bottom wall of the housing without increasing the thickness of the housing. It avoids the deformation of the bottom wall of the housing after the pressure relief valve is welded and installed in the pressure relief hole, improves the flatness of the area on the bottom wall of the housing around the pressure relief valve, ensures the reliability of the installation and welding of the pressure relief valve on the bottom wall of the housing, and improves the fatigue strength of the bottom wall of the housing and the pressure relief valve, ensuring the safety of the battery cell.

[0007] In one optional embodiment, the pressure relief hole is provided with the boss on both sides along the X direction.

[0008] Beneficial effects: It can further enhance the overall structural strength of the bottom wall of the shell and further improve the reliability of the shell.

[0009] In one optional embodiment, the thickness of the bottom wall of the shell along the Z direction is H, and the protrusion of the boss along the Z direction from the bottom wall of the shell is h. Wherein, 0.3 mm ≤ h ≤ 2H; and / or, 0.8 mm ≤ H ≤ 2 mm.

[0010] Beneficial effects: By limiting h to a value between 0.3 mm and 2H, it is possible to ensure that the boss can be smoothly processed and formed, and that the boss has sufficient strength, thereby effectively improving the structural strength of the bottom wall of the shell. This ensures that the shell still has strong structural strength after the pressure relief valve is welded, thus improving reliability. And / or, limiting the thickness H of the bottom wall body to between 0.8 mm and 2 mm can ensure that the bottom wall of the shell has sufficient structural strength, providing effective safety protection, while avoiding excessive shell weight, saving costs, and helping to improve the overall energy density of the battery cell.

[0011] In one alternative embodiment, the boss is provided with a plurality of reinforcing grooves.

[0012] Beneficial effects: By setting several reinforcing grooves on the boss, the surface of the boss forms an alternating concave-convex structure, which effectively improves the structural strength of the boss, thereby further ensuring the structural reinforcement effect of the boss on the bottom wall of the shell, and ensuring that the strength still meets the requirements after the pressure relief valve 4 is welded to the bottom of the shell.

[0013] In one optional embodiment, the reinforcing groove is located on the side of the boss away from the receiving cavity along the Z direction; And / or, the reinforcing groove is an elongated groove extending along the Y direction, and the width of the reinforcing groove along the X direction is W, wherein 0.05 mm ≤ W ≤ 0.5 mm; And / or, the groove depth of the reinforcing groove along the Z direction is H1, and the wall thickness of the boss along the Z direction is H2, wherein 0.05≤H1 / H2≤0.3, and / or, 0.1 mm≤H1≤0.3 mm.

[0014] Beneficial effects: Limiting the width W of the reinforcing groove to the range of 0.05 mm to 0.5 mm not only facilitates the processing and forming of the reinforcing groove, but also effectively improves the structural strength of the boss, ensuring the reinforcement effect on the structural strength of the boss. And / or, by limiting H1 / H2 to a value within the range of 0.05 to 0.3, the reinforcing groove can be guaranteed to strengthen the boss, while avoiding excessive damage to the boss due to excessive groove depth, thereby ensuring that the boss has strong structural strength and fatigue resistance. And / or, the groove depth H1 of the reinforcing groove 151 is limited to the range of 0.1 mm to 0.3 mm, which not only facilitates the processing and forming of the reinforcing groove, but also fully utilizes the structural reinforcement effect of the reinforcing groove on the boss, further improving the overall structural strength of the bottom of the shell.

[0015] In one optional embodiment, the boss has a dimension of L1 along the X direction, and the distance between two adjacent reinforcing grooves along the X direction is L2. Among them, L2 and L1 satisfy the relationship: 0.2≤L2 / L1≤0.5; And / or, the value range of L1 is: 20 mm ≤ L1 ≤ 100 mm.

[0016] Beneficial effects: By limiting the value of L2 / L1 to the range of 0.2 to 0.5, the fatigue strength of the boss can be effectively increased by reinforcing grooves, while avoiding the damage to the strength of the boss due to excessively dense reinforcing grooves, thereby ensuring the reliability of the boss. And / or, limiting L1 to a value within the range of 20 mm to 100 mm can ensure that the boss is successfully stamped and formed, and ensure that the boss strengthens the structural strength of the bottom wall of the shell.

[0017] In one optional embodiment, the pressure relief hole has a plurality of protrusions on the same side along the X direction, and the distance between two adjacent protrusions along the X direction is greater than or equal to 2 mm.

[0018] Beneficial effects: It further ensures the strengthening effect of the boss on the bottom wall structure of the shell, and at the same time can avoid interference between two adjacent bosses during the stamping process, ensuring the formability of the boss and ensuring the forming yield.

[0019] In one alternative embodiment, the boss forms a groove on one side of the receiving cavity along the Z direction; And / or, along the Y direction, the bottom wall of the shell has two first side edges arranged opposite each other, and the distance between the boss and the first side edge is A1, wherein A1≥2 mm; And / or, along the X direction, the bottom wall of the shell has two opposing second sides, and the distance between the boss and one of the adjacent second sides is A2, wherein A2 ≥ 2 mm; And / or, along the X direction, the distance between the boss and the pressure relief hole is B, where 5 mm ≤ B ≤ 10 mm.

[0020] Beneficial effects: By setting the side of the boss facing the receiving cavity as a groove, and the groove communicating with the receiving cavity, the internal space of the cell is increased. The groove can be used to store more free electrolyte, which is beneficial to improving the cycle life of the cell. And / or, by limiting the distance between the boss and the first side and the second side to not less than 2 mm, the smooth forming of the boss and the structural strength after forming can be guaranteed. And / or, by limiting B to a value within the range of 5 mm to 10 mm, it is possible to ensure the smooth forming of the boss and avoid the boss affecting the flatness of the mounting surface at the pressure relief hole, while also ensuring that the boss effectively improves the flatness around the pressure relief valve, thereby ensuring the reliability of the installation and use of the pressure relief valve.

[0021] Secondly, the present invention also provides a battery cell, comprising: the aforementioned housing, wherein one end of the housing away from the bottom wall along the Z direction is designated as an open end; a cover plate assembly covering the open end of the housing; an electrode assembly disposed in a receiving cavity of the housing; and a pressure relief valve installed in a pressure relief hole on the housing. Since the battery cell includes a housing and has the same effects as the housing, it will not be described further here.

[0022] In one optional embodiment, the battery cell further includes a base plate disposed in the receiving cavity and located between the electrode group and the bottom wall of the casing. The base plate has a weak portion, which is disposed opposite to a pressure relief hole on the bottom wall of the casing.

[0023] Beneficial effects: By setting a weak point on the bottom plate corresponding to the pressure relief valve, when thermal runaway occurs inside the battery cell and the internal air pressure is too high, the weak point and the pressure relief valve can be broken through, so as to release air and pressure in time, avoid the battery cell from exploding, and reduce the danger caused by thermal runaway of the battery cell. Attached Figure Description

[0024] 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.

[0025] Figure 1 An exploded view of the bottom structure of a housing according to an embodiment of the present invention; Figure 2 for Figure 1 The bottom view of the casing shown; Figure 3 for Figure 2 A magnified view of part of F; Figure 4 for Figure 2 Cross-sectional view along the EE direction; Figure 5 for Figure 4 A magnified view of a portion of G; Figure 6 This is a schematic diagram of the structure of a battery cell according to an embodiment of the present invention; Figure 7 for Figure 6 The diagram shows the structure of the battery cell from the bottom view. Figure 8 for Figure 6 The exploded view of the battery cell shown; Figure 9 for Figure 6 A top view of the battery cell shown; Figure 10 for Figure 9 A cross-sectional view along the CC direction; Figure 11 for Figure 10 A magnified view of part of E in the diagram; Figure 12 for Figure 9 A cross-sectional view along the DD direction; Figure 13 for Figure 12 A magnified view of a portion of the shell near the bottom wall; Figure 14 This is a schematic diagram of the structure of a base plate according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures: 1. Shell; 11. Shell bottom wall; 111. First side; 112. Second side; 12. Shell side wall; 13. Receiving cavity; 14. Pressure relief hole; 15. Boss; 151. Reinforcing groove; 16. Groove; 2. Cover plate assembly; 21. Cover plate body; 211. Liquid injection hole; 22. Electrode structure; 23. Hole plug; 24. Hole cover; 3. Electrode group; 31. Insulating film; 4. Pressure relief valve; 41. Pressure relief valve patch; 5. Bottom support plate; 51. Weak part; 52. First through hole; 6. Connecting piece. Detailed Implementation

[0027] 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.

[0028] A battery cell mainly consists of a casing, a cover plate assembly covering the opening of the casing, and electrode assemblies housed within the casing cavity. In related technologies, the electrode post structure is located on the cover plate body at one end of the cell, while the pressure relief valve is located at the bottom of the casing at the other end. This allows for thermoelectric separation in the event of battery thermal runaway, preventing secondary contact between the ejected electrolyte and electrode debris with the electrode post structure. However, because the bottom of the casing is generally relatively thin, and the casing wall thickness (0.8 mm~1.5 mm) is generally lower than the thickness of the cover plate body (1.5 mm~3.0 mm), the strength of the pressure relief valve welded to the bottom of the casing is relatively weak, making it prone to deformation. This results in poor fatigue resistance of the pressure relief valve, which is detrimental to ensuring the safety of the battery cell.

[0029] The following is combined Figures 1 to 14 The following describes embodiments of the present invention.

[0030] According to an embodiment of the present invention, a housing 1 is provided, comprising: a bottom wall 11 and a plurality of side walls 12, the side walls 12 being connected to one side of the bottom wall 11 along the Z direction, the bottom wall 11 and the plurality of side walls 12 forming a receiving cavity 13; the bottom wall 11 is provided with a pressure relief hole 14 and a boss 15, the boss 15 and the pressure relief hole 14 being spaced apart along the X direction, the bottom wall 11 having a first surface away from the receiving cavity 13 along the Z direction, and the boss 15 protruding from the first surface along the Z direction. A pressure relief valve 4 is adapted to be installed in the pressure relief hole 14, and the pressure relief valve 4 can be installed and fixed in the pressure relief hole 14 by welding.

[0031] It should be noted that, as Figure 1 As shown, the housing 1 has intersecting X, Y, and Z directions, where the X direction is the length direction of the housing 1, the Y direction is the width direction of the housing 1, and the Z direction is the height direction of the housing 1. Preferably, the X, Y, and Z directions are perpendicular to each other. The side of the bottom wall 11 facing away from the receiving cavity 13 along the Z direction is the first surface, and along the Z direction, the boss 15 protrudes from the first surface in a direction away from the receiving cavity 13.

[0032] In the housing 1 of this embodiment, a pressure relief hole 14 is provided on the bottom wall 11 of the housing, and a boss 15 spaced apart from the pressure relief hole 14 is provided on the bottom wall 11 of the housing. The provision of the boss 15 changes the structural shape of the bottom of the housing, so that the bottom of the housing 1 forms a reinforced structure with concave and convex joints. Compared with the traditional flat housing wall, it can effectively improve the structural strength of the bottom wall 11 of the housing without increasing the thickness of the housing. This avoids the deformation of the bottom wall 11 of the housing after the pressure relief valve 4 is welded and installed in the pressure relief hole 14, improves the flatness of the area of ​​the bottom wall 11 of the housing around the pressure relief valve 4, ensures the reliability of the installation and welding of the pressure relief valve 4 on the bottom wall 11 of the housing, and improves the fatigue strength of the bottom wall 11 of the housing and the pressure relief valve 4, ensuring the safety of the battery cell.

[0033] In one embodiment, the pressure relief hole 14 is provided with bosses 15 on both sides along the X direction. It should be noted that the bottom wall 11 of the shell has a large dimension along the X direction. By providing bosses 15 on both sides of the pressure relief hole 14 along the X direction, that is, by reinforcing the structure on both sides of the pressure relief hole 14, the overall structural strength of the bottom wall 11 of the shell can be further improved, and the reliability of the shell 1 can be further improved.

[0034] It should be noted that the protrusions 15 on both sides of the pressure relief hole 14 along the X direction have equal heights along the Z direction, which improves the flatness of the bottom of the housing and ensures that the housing 1 can be placed stably or stably abut against adjacent cells, avoiding the problem of unstable placement of the housing 1 caused by a protrusion 15 on one side. The protrusions 15 are located on the outside and do not occupy the space of the receiving cavity 13 inside the housing 1, nor do they encroach on the space for the electrode group 3 and electrolyte, which helps to ensure the energy density of the cells.

[0035] In one embodiment, the pressure relief hole 14 is centrally located on the bottom wall 11 of the shell along the X direction, and the bosses 15 on both sides of the pressure relief hole 14 are symmetrically arranged along the X direction, which reduces the molding difficulty and helps to improve processing efficiency.

[0036] In one embodiment, further combination Figures 4 to 5 As shown, the wall thickness of the bottom wall 11 along the Z direction is H, and the protrusion of the boss 15 along the Z direction from the bottom wall 11 is h; where 0.3 mm ≤ h ≤ 2H. It should be noted that the boss 15 is formed by stamping, and h is the stamped height of the boss 15. If h is less than 0.3 mm, the height of the boss 15 protruding from the bottom wall 11 is too small, which places too high demands on the processing equipment and makes forming difficult. If h is greater than 2H, that is, the protrusion height of the boss 15 is greater than twice the thickness of the bottom wall 11, the height of the boss 15 protruding from the bottom wall 11 is too large, the stability of the boss 15 along the Z direction after forming is poor, the strength of the boss 15 is low, and it cannot effectively increase the structural strength of the bottom wall 11.

[0037] Therefore, by limiting h to a value between 0.3 mm and 2H, it is possible to ensure that the boss 15 can be smoothly processed and formed, and that the boss 15 has sufficient strength, thereby effectively improving the structural strength of the bottom wall 11 of the shell, ensuring that the shell 1 still has strong structural strength after the pressure relief valve 4 is welded, and improving reliability.

[0038] In one embodiment, 0.8 mm ≤ H ≤ 2 mm. Here, H is the thickness of the bottom wall 11. If H is less than 0.8 mm, the bottom wall 11 is too thin, resulting in insufficient structural strength. Even with the additional protrusion 15, the required structural strength cannot be achieved, failing to guarantee the safe use of the pressure relief valve 4 and providing adequate protection for the electrode assembly 3 inside the housing 1. If H is greater than 2 mm, the bottom wall 11 is too thick, excessively increasing the overall weight of the housing 1, causing unnecessary material waste, and reducing the effective space inside the housing 1, thus lowering the overall energy density of the battery cell. Therefore, limiting the thickness H of the bottom wall to between 0.8 mm and 2 mm ensures sufficient structural strength for effective safety protection while avoiding excessive weight of the housing 1, saving costs, and improving the overall energy density of the battery cell.

[0039] Optionally, the value of H is any one of 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm, or a value between any two of these values.

[0040] In one embodiment, further combination Figures 1 to 2 As shown, the boss 15 is provided with several reinforcing grooves 151. By providing several reinforcing grooves 151 on the boss 15, the surface of the boss 15 forms an alternating concave-convex structure, which effectively improves the structural strength of the boss 15, thereby further ensuring the structural reinforcement effect of the boss 15 on the bottom wall 11 of the shell, and ensuring that the strength still meets the requirements after the pressure relief valve 4 is welded to the bottom of the shell.

[0041] In one embodiment, the reinforcing groove 151 is provided on the side of the boss 15 away from the receiving cavity 13 along the Z direction. By providing a groove-shaped structure on the side of the boss 15 away from the receiving cavity 13, the structure is simple and easy to process. It does not increase the height of the boss 15 along the Z direction, and therefore does not increase the total height of the battery cell along the Z direction, which is beneficial to ensuring the energy density of the battery cell.

[0042] In one embodiment, further combination Figure 3As shown, the reinforcing groove 151 is an elongated groove extending along the Y direction, and its width along the X direction is W, where 0.05 mm ≤ W ≤ 0.5 mm. It should be noted that several reinforcing grooves 151 are spaced apart along the X direction, and W is the width of a single reinforcing groove 151 along the X direction. If W is less than 0.05 mm, the reinforcing groove 151 is too narrow, requiring excessively high machining precision, increasing machining difficulty and production costs. If W is greater than 0.5 mm, the reinforcing groove 151 is too wide, occupying too much surface area of ​​the boss 15, which would reduce the overall structural strength of the boss 15 and fail to effectively strengthen its structural strength. Therefore, limiting the width W of the reinforcing groove 151 to the range of 0.05 mm to 0.5 mm facilitates the machining and forming of the reinforcing groove 151 while effectively improving the structural strength of the boss 15, ensuring a strengthening effect on the structural strength of the boss 15.

[0043] Optionally, the value of W is any one of 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, or a value between any two of these values.

[0044] In one embodiment, further combination Figure 5 As shown, the groove depth of the reinforcing groove 151 along the Z direction is H1, and the wall thickness of the boss 15 along the Z direction is H2, where 0.05 ≤ H1 / H2 ≤ 0.3. It should be noted that H1 is the groove depth of the reinforcing groove 151 along the Z direction, and H2 is the wall thickness of the boss 15. If H1 / H2 is less than 0.05, the groove depth of the reinforcing groove 151 is too small relative to the wall thickness of the boss 15, failing to effectively strengthen the structural strength of the boss 15, resulting in poor fatigue strength of the boss 15. If H1 / H2 is greater than 0.3, the groove depth of the reinforcing groove 151 is too large relative to the wall thickness of the boss 15, resulting in insufficient thickness of the remaining solid portion of the boss 15 along the Z direction corresponding to the reinforcing groove 151, leading to insufficient strength of the boss 15. Therefore, by limiting the values ​​of H1 / H2 to within the range of 0.05 to 0.3, the reinforcing effect of the reinforcing groove 151 on the boss 15 can be guaranteed, while avoiding excessive damage to the boss 15 due to excessive groove depth of the reinforcing groove 151, thereby ensuring that the boss 15 has strong structural strength and fatigue resistance.

[0045] Optionally, the value of H1 / H2 is any one of 0.05, 0.08, 0.1, 0.12, 0.15, 0.18, 0.2, 0.22, 0.25, 0.28, 0.3 or a value between any two values.

[0046] In one embodiment, 0.1 mm ≤ H1 ≤ 0.3 mm. If H1 is less than 0.1 mm, the depth of the reinforcing groove 151 is too small, resulting in limited structural reinforcement of the boss 15 and failing to achieve the expected reinforcement effect. Furthermore, it increases processing difficulty and molding costs. If H1 is greater than 0.3 mm, the depth of the reinforcing groove 151 is too large, leading to insufficient thickness of the remaining solid portion along the Z direction after the reinforcing groove 151 is opened on the boss 15. This can easily cause cracking of the boss 15 during the grooving process, thus reducing the overall structural strength of the boss 15. Therefore, limiting the groove depth H1 of the reinforcing groove 151 to the range of 0.1 mm to 0.3 mm facilitates the processing and molding of the reinforcing groove 151 while fully utilizing its structural reinforcement effect on the boss 15, further enhancing the overall structural strength of the bottom of the shell.

[0047] Optionally, the value of H1 is any one of 0.1 mm, 0.12 mm, 0.15 mm, 0.18 mm, 0.2 mm, 0.22 mm, 0.25 mm, 0.28 mm, 0.3 mm, or a value between any two of these values.

[0048] In one embodiment, the wall thickness H2 of the boss 15 along the Z direction is equal to the wall thickness H of the bottom wall 11 along the Z direction. The boss 15 is formed by stamping, which is convenient for processing.

[0049] In one embodiment, further combination Figure 2 As shown, the dimension of the boss 15 along the X direction is L1, and the distance between two adjacent reinforcing grooves 151 along the X direction is L2; ​​where L2 and L1 satisfy the relationship: 0.2≤L2 / L1≤0.5. If L2 / L1 is less than 0.2, the distance between two adjacent reinforcing grooves 151 on the same boss 15 is too close, the reinforcing grooves 151 on the boss 15 are too dense, and the groove structure damages too much of the solid part of the boss 15, resulting in a decrease in the strength of the boss 15; if L2 / L1 is greater than 0.5, the reinforcing grooves 151 on the same boss 15 are too sparse, which cannot effectively improve the fatigue strength of the boss 15. Therefore, by limiting the value of L2 / L1 to the range of 0.2 to 0.5, the fatigue strength of the boss 15 can be effectively increased by the reinforcing grooves 151, while avoiding the strength of the boss 15 due to excessive density of the reinforcing grooves 151, thereby ensuring the reliability of the boss 15.

[0050] Optionally, the value of L2 / L1 is any one of 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5 or a value between any two of these values.

[0051] In one embodiment, the value of L1 is in the range of 20 mm ≤ L1 ≤ 100 mm. If L1 is less than 20 mm, the length of the boss 15 along the X direction is insufficient, the strengthening effect of the boss 15 on the structural strength of the shell bottom wall 11 is insufficient, and it is not easy to stamp. If L1 is greater than 100 mm, the length of the boss 15 along the X direction is too large, and it is not easy to stamp. Therefore, limiting L1 to a value in the range of 20 mm to 100 mm can ensure that the boss 15 can be stamped smoothly and that the strengthening effect of the boss 15 on the structural strength of the shell bottom wall 11 is guaranteed.

[0052] Optionally, the value of L1 is any one of 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, or a value between any two of these values.

[0053] In one embodiment, the pressure relief hole 14 has multiple bosses 15 on the same side along the X direction, and the distance between two adjacent bosses 15 along the X direction is greater than or equal to 2 mm. By providing multiple bosses 15 on the same side of the pressure relief hole 14 along the X direction, the space on the bottom wall 11 where the pressure relief hole 14 is not provided can be fully utilized, and the size of a single boss 15 along the X direction can be avoided from being too large and difficult to form, further ensuring the strengthening effect of the bosses 15 on the structural strength of the bottom wall 11. At the same time, limiting the distance between two adjacent bosses 15 on the same side to not less than 2 mm can avoid interference between two adjacent bosses 15 during the stamping process, ensuring the formability of the bosses 15 and ensuring the forming yield.

[0054] In one embodiment, further combination Figure 5 and Figure 13 As shown, the boss 15 forms a groove 16 along the Z-direction towards the receiving cavity 13. It should be noted that the boss 15 is formed by stamping a portion of the bottom wall 11 along the Z-direction away from the receiving cavity 13, creating a boss 15 on the outside of the housing 1 and correspondingly forming a groove 16 on the inside of the housing 1. The receiving cavity 13 of the housing 1 contains the electrode assembly 3 and electrolyte. During the cycle of use, the battery cell consumes a certain amount of electrolyte. If the housing 1 contains sufficient electrolyte, the electrolyte lost during the cycle can be replenished in time, which is beneficial to improving the cycle life of the battery cell. By setting the side of the boss 15 facing the receiving cavity 13 as a groove 16, the boss 15 and the groove 16 together form a convex hull structure. The groove 16 communicates with the receiving cavity 13, increasing the internal space of the battery cell. The groove 16 can be used to store more free electrolyte, which is beneficial to improving the cycle life of the battery cell.

[0055] In one embodiment, further combination Figure 2As shown, along the Y direction, the bottom wall 11 of the shell has two opposing first side edges 111. The distance between the boss 15 and the first side edges 111 is A1, where A1 ≥ 2 mm. It should be noted that A1 is the distance from the boss 15 to the edge of the bottom wall 11 along the Y direction. If A1 is less than 2 mm, the boss 15 is too close to the edge of the bottom wall 11, making it difficult to form and resulting in lower structural strength after forming. Therefore, by limiting the distance between the boss 15 and the first side edges 111 to no less than 2 mm, the smooth forming of the boss 15 and the structural strength after forming can be guaranteed.

[0056] In one embodiment, along the X direction, the bottom wall 11 of the shell has two opposing second sides 112. The distance between the boss 15 and one of the second sides 112 closest to it is A2, where A2 ≥ 2 mm. A2 is the distance from the boss 15 closest to the edge of the bottom wall 11 along the X direction to the edge of the bottom wall 11. By limiting the distance between the boss 15 and the second side 112 to not less than 2 mm, the smooth forming of the boss 15 and the structural strength after forming can be guaranteed.

[0057] It should be noted that further integration Figure 10 As shown, the pressure relief hole 14 is configured as a stepped hole, pointing from the receiving cavity 13 to the outside of the housing along the Z direction. The pressure relief hole 14 includes a first hole section, a second hole section, and a third hole section whose outer periphery contours increase sequentially. The second hole section has a first stepped surface at one end near the first hole section, and the third hole section has a second stepped surface at one end near the second hole section. The pressure relief valve 4 is installed in the second hole section, with the first stepped surface serving as the mounting surface of the pressure relief valve 4. The pressure relief valve patch 41 is installed in the third hole section, with the second stepped surface serving as the mounting surface of the pressure relief valve patch 41. The pressure relief valve patch 41 protects the pressure relief valve 4.

[0058] In one embodiment, further combination Figure 2 As shown, along the X direction, the distance between the boss 15 and the pressure relief hole 14 is B, where 5 mm ≤ B ≤ 10 mm. If B is less than 5 mm, the distance between the boss 15 and the pressure relief hole 14 is too small, making forming difficult, and the stamped boss 15 affects the flatness of the mounting surface of the pressure relief hole 14, which is not conducive to the stable installation of the pressure relief valve 4 and can easily cause problems such as air leakage. If B is greater than 10 mm, the distance between the boss 15 and the pressure relief hole 14 is too large, and the boss 15 does not provide sufficient structural strength reinforcement to the area around the pressure relief hole 14 on the bottom wall 11 of the housing. After welding the pressure relief valve 4 into the pressure relief hole 14, the improvement on the flatness around the pressure relief valve 4 is limited. Therefore, by limiting B to a value within the range of 5 mm to 10 mm, it is possible to ensure the smooth forming of the boss 15 and avoid the boss 15 affecting the flatness of the mounting surface at the pressure relief hole 14, while also ensuring the effective improvement of the flatness around the pressure relief valve 4 by the boss 15, thereby ensuring the reliability of the installation and use of the pressure relief valve 4.

[0059] Optionally, the value of B is any one of 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm, 7.5 mm, 8 mm, 8.5 mm, 9 mm, 9.5 mm, 10 mm, or a value between any two of these values.

[0060] According to an embodiment of the present invention, another aspect provides a battery cell, comprising: the aforementioned housing 1, cover plate assembly 2, electrode group 3, and pressure relief valve 4. The end of the housing 1 away from the bottom wall 11 along the Z direction is provided as an open end; the cover plate assembly 2 is provided covering the open end of the housing 1; the electrode group 3 is disposed in the receiving cavity 13 of the housing 1; and the pressure relief valve 4 is installed in the pressure relief hole 14 on the housing 1.

[0061] The cover plate assembly 2 includes a cover plate body 21 and an electrode post structure 22. The cover plate body 21 is placed over the opening end of the housing 1 and welded to the housing 1. The electrode post structure 22 is disposed on the cover plate body 21 and electrically connected to the electrode tabs of the electrode group 3. In this way, the electrode post structure 22 and the pressure relief valve 4 on the bottom wall 11 of the housing are located at opposite ends of the battery cell along the Z direction, with a large distance between them. This can achieve thermoelectric separation in the event of thermal runaway of the battery cell, and prevent the electrolyte and electrode fragments ejected during thermal runaway from secondary contact with the electrode post structure 22, which could further cause a short circuit and prevent the spread of danger. At the same time, the protrusion 15 on the bottom wall 11 of the housing improves the structural strength and flatness of the bottom of the housing, which can solve the problem of housing deformation after welding the pressure relief valve 4 to the bottom of the housing.

[0062] In one embodiment, the battery cell further includes a base plate 5, disposed in the receiving cavity 13 and located between the electrode group 3 and the bottom wall 11 of the casing. The base plate 5 has a weak portion 51, which is opposite to the pressure relief hole 14 on the bottom wall 11 of the casing. By providing a weak portion 51 on the base plate 5 corresponding to the pressure relief valve 4, when thermal runaway occurs inside the battery cell and the internal gas pressure is too high, the weak portion 51 and the pressure relief valve 4 can be broken through, achieving timely gas release and pressure relief, preventing the battery cell from exploding, and reducing the danger caused by thermal runaway of the battery cell. Preferably, the weak portion 51 and the pressure relief hole 14 are directly opposite each other.

[0063] In one embodiment, further combination Figure 14 As shown, the weak part 51 on the base plate 5 is a discontinuous structure on the base plate 5. The structure is simple, easy to process, and can break in time when the internal air pressure of the battery cell is too high, increasing the pressure relief area and ensuring timely air release and pressure relief.

[0064] In one embodiment, further combination Figure 14As shown, the bottom plate 5 is also provided with a number of first through holes 52. The first through holes 52 are located at positions corresponding to the boss 15, ensuring that the electrolyte in the receiving cavity 13 of the housing 1 can flow through the first through holes 52 into the groove 16 formed by the boss 15, thereby making full use of the space of the groove 16 to store more free electrolyte, which is beneficial to improving the cycle life of the battery cell.

[0065] In one embodiment, the cover plate body 21 is further provided with an injection hole 211, which penetrates the cover plate body 21 along the Z direction for injecting electrolyte into the cell; the cover plate assembly also includes a plug 23 and a cover 24. When electrolyte is not needed, the plug 23 blocks the injection hole 211, and the cover 24 is placed on the side of the injection hole 211 away from the receiving cavity 13 along the Z direction to avoid electrolyte leakage inside the housing 1 and to ensure the cell's sealing.

[0066] In one embodiment, the battery cell further includes an insulating film 31, which wraps around the electrode group 3 to improve the insulation between the electrode group 3 and the inner wall of the housing 1 and to protect the electrode group 3.

[0067] In one embodiment, the battery cell further includes a connecting piece 6, which is disposed between the electrode group 3 and the cover plate assembly 2. A portion of the connecting piece 6 is welded to the tabs on the electrode group 3, and another portion is welded to the pole post structure 22, thereby realizing the electrical connection between the tabs and the pole post structure 22.

[0068] The following examples and comparative examples verify the impact of different parameter values ​​on the battery cell. The parameter settings and corresponding results for the examples and comparative examples are shown in Table 1. The test items are as follows: 1. Fatigue index: The cell casing is filled with air at 0.3 MPa to simulate the gas production state during normal cell use. If the pressure relief valve does not open after 3000 cycles and the bottom of the casing and the pressure relief valve do not deform, then the fatigue index requirement is met. 2. Boss strength test: The boss is required to withstand a pressure of more than 1.2 MPa without deformation (or the maximum pressure that the boss can withstand when deformed is 1.2 MPa).

[0069] Table 1

[0070] As can be seen from Table 1, for the battery cells of Examples 1 to 10, all parameters are within the range defined in this application. After testing the battery cells, the fatigue index meets the requirements, and the boss strength meets the requirements. The test conclusion is OK (i.e., the battery cell is qualified).

[0071] For the cells in Comparative Examples 1 to 3, no protrusions were provided on the bottom wall of the casing. The test results showed that the cells did not meet the fatigue index. After 3000 cycles, the bottom of the casing and the explosion-proof valve were deformed, and the flatness was >0.3, so the cells were NG (i.e., unqualified). It can be seen that by providing protrusions on the bottom wall of the casing, its fatigue strength can be increased.

[0072] For the cell in Comparative Example 4, the H1 / H2 value is 0.31, which is greater than the upper limit of H1 / H2 (0.3) defined in this application and is not within the range defined in this application. Although the cell meets the fatigue index, its boss strength is 0.95 MPa, which is less than 1.2 MPa, and therefore does not meet the requirements. The cell is NG (i.e., unqualified). For the cell in Comparative Example 5, the H1 / H2 value is 0.04, which is less than the lower limit of H1 / H2 (0.05) defined in this application and is not within the range defined in this application. Although the boss strength is greater than 1.2 MPa, the fatigue index does not meet the requirements, and the cell is NG (i.e., unqualified). It can be seen that when H1 / H2 is within the range of 0.05 to 0.3, both boss strength and fatigue resistance can be considered.

[0073] For the cell of Comparative Example 6, the value of L2 / L1 is 0.53, which is greater than the upper limit of L2 / L1 of 0.5 defined in this application and is not within the range defined in this application. Although the boss strength is greater than 1.2 MPa, the fatigue index does not meet the requirements, and the cell is rejected. For the cell of Comparative Example 7, the value of L2 / L1 is 0.15, which is less than the lower limit of L2 / L1 of 0.2 defined in this application and is not within the range defined in this application. Although the cell meets the fatigue index, the boss strength is 1.05 MPa, which is less than 1.2 MPa and does not meet the requirements, so the cell is rejected. It can be seen that when L2 / L1 is taken within the range of 0.2 to 0.5 defined in this application, both boss strength and fatigue resistance can be taken into account.

[0074] Unless otherwise stated, the values ​​of all parameters mentioned in this application can be determined using testing methods commonly used in the art. Unless otherwise stated, the test temperature for all parameters is 25°C.

[0075] 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 housing, characterized in that, include: The shell has a bottom wall and multiple shell side walls, the shell side walls being connected to one side of the bottom wall along the Z direction, and the bottom wall and the multiple shell side walls forming a receiving cavity; The bottom wall of the shell is provided with a pressure relief hole and a boss. The boss and the pressure relief hole are spaced apart along the X direction. The bottom wall of the shell has a first surface that is away from the receiving cavity along the Z direction. The boss protrudes from the first surface along the Z direction.

2. The housing according to claim 1, characterized in that, The pressure relief hole is provided with the boss on both sides along the X direction.

3. The housing according to claim 1, characterized in that, The thickness of the bottom wall of the shell along the Z direction is H, and the protrusion of the boss along the Z direction from the bottom wall of the shell is h. Wherein, 0.3 mm ≤ h ≤ 2H; and / or, 0.8 mm ≤ H ≤ 2 mm.

4. The housing according to claim 1, characterized in that, The boss is provided with several reinforcing grooves.

5. The housing according to claim 4, characterized in that, The reinforcing groove is located on the side of the boss away from the receiving cavity along the Z direction; And / or, the reinforcing groove is an elongated groove extending along the Y direction, and the width of the reinforcing groove along the X direction is W, wherein 0.05 mm ≤ W ≤ 0.5 mm; And / or, the groove depth of the reinforcing groove along the Z direction is H1, and the wall thickness of the boss along the Z direction is H2, wherein 0.05≤H1 / H2≤0.3, and / or, 0.1 mm≤H1≤0.3 mm.

6. The housing according to claim 4, characterized in that, The boss has a dimension of L1 along the X direction, and the distance between two adjacent reinforcing grooves along the X direction is L2. Among them, L2 and L1 satisfy the relationship: 0.2≤L2 / L1≤0.5; And / or, the value range of L1 is: 20 mm ≤ L1 ≤ 100 mm.

7. The housing according to claim 2, characterized in that, The pressure relief hole has multiple protrusions on the same side along the X direction, and the distance between two adjacent protrusions along the X direction is greater than or equal to 2 mm.

8. The housing according to any one of claims 1 to 7, characterized in that, The boss forms a groove on one side of the receiving cavity along the Z direction; And / or, along the Y direction, the bottom wall of the shell has two first side edges arranged opposite each other, and the distance between the boss and the first side edge is A1, wherein A1≥2 mm; And / or, along the X direction, the bottom wall of the shell has two opposing second sides, and the distance between the boss and one of the adjacent second sides is A2, wherein A2 ≥ 2 mm; And / or, along the X direction, the distance between the boss and the pressure relief hole is B, where 5 mm ≤ B ≤ 10 mm.

9. A battery cell, characterized in that, include: The housing according to any one of claims 1 to 8, wherein the end of the housing away from the bottom wall along the Z direction is provided as an open end; A cover plate assembly is provided to cover the opening end of the housing; The pole assembly is located in the receiving cavity of the housing; A pressure relief valve is installed in the pressure relief hole on the housing.

10. The battery cell according to claim 9, characterized in that, The battery cell further includes a bottom support plate, which is disposed in the receiving cavity and located between the electrode group and the bottom wall of the casing. The bottom support plate has a weak part, which is disposed opposite to the pressure relief hole on the bottom wall of the casing.

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