Cell cover assembly, cell and battery pack

Abstract

This invention relates to the field of battery technology and discloses a cell cover assembly, a cell, and a battery pack. The cell cover assembly includes: a riveting block with a first through hole and a second through hole coaxially arranged, the first through hole being larger than the second through hole, and a first stepped surface forming at the connection between the first and second through holes; an electrode post including a main riveting section and a secondary riveting section, the main riveting section being located within the first through hole and fitting against the hole wall and the first stepped surface, and the secondary riveting section being located within the second through hole and fitting against the hole wall; the contact area between the main riveting section and the first stepped surface is S; the yield strength of the electrode post and the riveting block is σ, with σ ranging from 75 MPa ≤ σ ≤ 140 MPa; the riveting block is subjected to a tensile force F along the axial direction of the electrode post, with F ranging from 800 N ≤ F ≤ 1500 N; S, σ, and F satisfy the condition: σ × S > 1.2 F. This invention improves the structural stability and reliability of the cell cover assembly by defining the relationship between S, σ, and F.

Description

Technical Field

[0001] This invention relates to the field of battery technology, specifically to a cell cover assembly, a cell, and a battery pack. Background Technology

[0002] A typical battery cell cover assembly consists of a terminal post, a rivet block, a smooth aluminum sheet, an upper plastic insert, a lower plastic insert, and a sealing ring. The sealing ring, lower plastic insert, smooth aluminum sheet, upper plastic insert, and rivet block sequentially pass through the terminal post. A punch presses the terminal post head, utilizing the inherent fluidity of the terminal post material (e.g., copper or aluminum) to deform it and rivet the battery cell cover assembly together. Laser welding is then used to further secure the terminal post and the rivet block at their joint. However, during subsequent cell manufacturing or use, the rivet block may be subjected to forces that cause it to move away from the terminal post. This can lead to the rivet block detaching from the terminal post, causing leakage and compromising the safety of the battery cell. Summary of the Invention

[0003] In view of this, the present invention provides a cell cover assembly, a cell, and a battery pack to solve the problem that the rivet block is prone to separating from the terminal under tensile force, resulting in cell leakage.

[0004] In a first aspect, the present invention provides a battery cell cover assembly, comprising:

[0005] The riveting block has a first through hole and a second through hole arranged coaxially. The size of the first through hole is larger than the size of the second through hole, and a first stepped surface is formed at the connection between the first through hole and the second through hole.

[0006] The pole includes a main riveting section and a secondary riveting section. The main riveting section is located inside the first through hole and is in contact with the hole wall of the first through hole and the first stepped surface. The secondary riveting section is located inside the second through hole and is in contact with the hole wall of the second through hole.

[0007] The contact area between the main riveting section and the first step surface is S; the yield strength of the pole post and the riveting block is σ, and the value range of σ is 75 MPa ≤ σ ≤ 140 MPa; the riveting block is subjected to a tensile force F along the axial direction of the pole post, and the value range of F is 800 N ≤ F ≤ 1500 N; S, σ, and F satisfy the following condition: σ × S > 1.2 F.

[0008] Beneficial effects: This invention designs the riveting block with a first through hole and a second through hole of different sizes and coaxially arranged, and allows the main riveting section and the secondary riveting section of the pole to be fitted and embedded respectively. The first stepped surface fits into the main riveting section to form a stable riveting structure. At the same time, by limiting the relationship between the contact area S between the main riveting section and the first stepped surface, the yield strength σ of the pole and the riveting block, and the axial tensile force F on the riveting block (σ×S>1.2F), it ensures that under the action of tensile force of 800N to 1500N, the connection strength between the pole and the riveting block is higher than the above tensile force. This can improve the riveting firmness between the pole and the riveting block, reduce the risk of the pole detaching from the riveting block, and thus reduce the possibility of electrolyte leakage through the gap between the pole and the riveting block, ensuring the safety and performance of the battery cell.

[0009] In one optional embodiment, the length direction of the cross-section of the pole post is consistent with the length direction of the riveting block; the riveting block is provided with a pair of welding areas, which are respectively located on opposite sides of the pole post in the length direction of the riveting block; along the length direction of the riveting block, the length of the riveting block is L1, the length of the main riveting segment is L2, and the length between any welding area and the main riveting segment is L3, wherein L1, L2, and L3 satisfy: 1 / 5 ≤ L3 / L2 ≤ 3 / 5, 0.15 ≤ L2 / L1 ≤ 0.3.

[0010] Beneficial effects: Generally, the width of the riveting block is relatively small. This invention aligns the length direction of the electrode's cross-section with that of the riveting block. This facilitates increasing the electrode's size, giving it a larger cross-sectional area (the section perpendicular to the direction of current flow within the electrode), thereby improving the cell's current carrying capacity. Furthermore, it allows workers to quickly determine the assembly direction of the electrode and riveting block, reducing assembly errors and improving efficiency. Secondly, the pair of welding areas on opposite sides of the electrode on the riveting block not only provides space for welding between the riveting block and the busbar but also maintains a suitable distance between the welding areas and the electrode, preventing the high temperatures generated during welding from adversely affecting the riveting structure. Furthermore, by defining the proportional relationship between L1, L2, and L3, this invention not only ensures sufficient operating space when welding the riveting block to the busbar, improving the convenience and accuracy of welding and guaranteeing welding quality, but also effectively balances the stress distribution of the overall structure of the riveting block, enhances the stability of the connection between the pole and the riveting block, and enables the cell cover assembly to maintain good performance and reliability when subjected to external forces and current loads, extending the service life of the assembly and reducing the risk of cell failure due to structural problems.

[0011] In one optional implementation, S, L1, L2, and L3 satisfy 9mm. 2 ≤S≤12mm 232mm≤L1≤65mm, 8.5mm≤L2≤15mm, 2mm≤L3≤10mm.

[0012] Beneficial effects: This invention controls S to 9mm 2 Up to 12mm 2 To ensure sufficient contact area between the pole and the main riveting section of the rivet block, meeting the strength requirement of "σ×S>1.2F", and improving the tensile strength of the connection between the pole and the rivet block; the setting of L1 from 32mm to 65mm and L2 from 8.5mm to 15mm ensures that the rivet block has a reasonable size to accommodate the pole, and that the length of the main riveting section is adapted to the rivet block, optimizing the force transmission path and avoiding insufficient connection strength due to improper length ratio; the value of L3 is 2mm to 10mm, which keeps the welding area and the main riveting section at a safe and easy-to-operate distance, which can prevent thermal damage to the pole riveting structure during welding, and also reserve sufficient space for welding fixtures, improving assembly efficiency and welding quality.

[0013] In one alternative embodiment, the pair of welding zones are arranged in a centrally symmetrical manner about the center of the pole.

[0014] Beneficial effects: The present invention arranges a pair of welding areas in a centrally symmetrical manner about the center of the pole, which enables the busbar and the rivet block to be welded together so that the force on both sides of the pole is uniform, avoiding stress concentration caused by unilateral force, thereby improving the overall structural stability of the cell cover assembly and reducing the risk of loosening and deformation at the connection between the pole and the rivet block.

[0015] In one optional embodiment, the pole post further includes a limiting section connected to the secondary riveting section, the limiting section being located outside the second through hole and abutting against the lower surface of the riveting block along the axial direction of the pole post.

[0016] Beneficial effects: The present invention fits the limiting section with the lower surface of the riveting block, which can restrict the axial movement of the pole post and ensure that the main riveting section and the secondary riveting section can correspond to the first through hole and the second through hole respectively. In this way, it can ensure that the pole post deforms uniformly along its radial direction during the riveting process and avoid irregular deformation of the riveting block due to excessive local stress.

[0017] In one optional embodiment, the end of the limiting segment away from the riveting block is provided with a pole post base, the central axis of the pole post is collinear with the central axis of the pole post base, and the central axis of the pole post is collinear with the central axis of the riveting block.

[0018] Beneficial Effects: To meet the welding requirements of the battery cell tabs, the eccentricity of the tabs cannot be too large or small. Therefore, in battery cells using a bipolar design, the base of one of the poles often cannot be welded to the tab, necessitating an increase in the length of the base of the other pole to ensure the cell's current-carrying capacity. However, the unused portion of the base and the extended portion of the base lead to reduced material utilization and increased production costs. Furthermore, in a bipolar battery cell, the two poles need to be spaced apart, requiring the pole to be eccentric relative to the base. Based on this, the present invention sets the central axis of the pole and the central axis of the base to be collinear. This not only optimizes the current conduction path and avoids performance losses and structural hazards caused by eccentricity, but also eliminates the need for an additional lengthened base in a single-pole design, thereby improving material utilization, reducing production costs, and enhancing the overall safety, reliability, and economy of the battery cell while meeting the requirements for current-carrying capacity and tab welding.

[0019] This invention arranges the central axis of the electrode post and the central axis of the rivet block collinearly, ensuring the symmetry and stability of the assembly. This avoids uneven stress on the electrode post and rivet block caused by eccentric installation, preventing loosening and deformation due to stress concentration during high current transmission, and improving connection reliability. Furthermore, the collinear design optimizes the current conduction path, allowing the current to pass through the electrode post and rivet block area along the shortest straight line, reducing contact resistance and energy loss, and stabilizing the resistance of the current-flowing area at a low level, thus suppressing temperature rise during charging and discharging.

[0020] In one alternative embodiment, the cross-sectional shape of the pole is shaped like an athletic track.

[0021] Beneficial effects: The present invention designs the cross-sectional shape of the electrode post as an athletic track, which allows the electrode post to obtain a larger effective current flow area in a limited space. Compared with the traditional shape (cylindrical), it can carry a larger current, which meets the fast charging requirements of the battery cell. At the same time, the shape of the athletic track optimizes the current distribution path, avoids the current concentration in local areas, reduces the resistance increase and heat generation caused by uneven current density, and ensures the temperature stability of the electrode post during charging and discharging.

[0022] In one optional embodiment, the riveting block is further provided with a welding hole coaxially disposed with the first through hole, the size of the welding hole being larger than the size of the first through hole, and the connection between the welding hole and the first through hole forming a second stepped surface.

[0023] Beneficial effects: The welding holes provide sufficient space for welding the electrode post and the rivet block, ensuring good contact between the electrode post and the rivet block during the welding process. This helps to improve the sealing performance of the welded part, prevent electrolyte leakage, and ensure the safety and reliability of the battery cell.

[0024] Secondly, the present invention also provides a battery cell, comprising:

[0025] The pole assembly has a pole tab at one end;

[0026] In the aforementioned cell cover assembly, the end of the electrode post furthest from the riveting block is welded to the electrode tab.

[0027] Beneficial effects: The battery cell of the present invention includes the battery cell cover assembly as described above, and has all the beneficial technical effects of the battery cell cover assembly, which will not be repeated here.

[0028] Thirdly, the present invention also provides a battery pack comprising: a plurality of the above-described battery cells.

[0029] Beneficial effects: The battery pack of the present invention includes the battery cell as described above, and has all the beneficial technical effects of the battery cell, which will not be repeated here. Attached Figure Description

[0030] 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.

[0031] Figure 1 This is a schematic diagram of the assembly of the riveting block and the pole post in an embodiment of the present invention;

[0032] Figure 2 for Figure 1 A sectional view;

[0033] Figure 3 for Figure 1 Exploded view;

[0034] Figure 4 for Figure 1 A cross-sectional view of the central riveting block;

[0035] Figure 5 for Figure 1 Cross-sectional view of the central pole;

[0036] Figure 6 This is a top view of the battery cell cover assembly after soldering marks have been formed in the welding area, according to an embodiment of the present invention.

[0037] Explanation of reference numerals in the attached figures:

[0038] 1. Riveting block; 101. First through hole; 102. Second through hole; 103. First stepped surface; 104. Welding area; 105. Welding hole; 106. Second stepped surface; 2. Pole post; 201. Main riveting section; 202. Secondary riveting section; 203. Limiting section; 204. Pole post base. Detailed Implementation

[0039] 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.

[0040] To address the problem that the rivet block is prone to separating from the terminal post under tensile force, leading to cell leakage, this invention provides a cell cover assembly, a cell, and a battery pack.

[0041] The following is combined Figures 1 to 6 The following describes embodiments of the present invention.

[0042] According to an embodiment of the present invention, in one aspect, such as Figures 1 to 5 As shown, a battery cell cover assembly is provided, including: a riveting block 1 and an electrode post 2.

[0043] Specifically, the riveting block 1 is provided with a first through hole 101 and a second through hole 102 arranged coaxially. The size of the first through hole 101 is larger than the size of the second through hole 102. The connection between the first through hole 101 and the second through hole 102 forms a first stepped surface 103. The pole post 2 includes a main riveting section 201 and a secondary riveting section 202. The main riveting section 201 is located in the first through hole 101 and is in contact with the hole wall of the first through hole 101 and the first stepped surface 103. The secondary riveting section 202 is located in the second through hole 102 and is in contact with the hole wall of the second through hole 102.

[0044] The contact area between the main riveting section 201 and the first step surface 103 is S. The yield strength of the pole post 2 and the riveting block 1 is σ, and the value range of σ is 75 MPa ≤ σ ≤ 140 MPa. The riveting block 1 is subjected to a tensile force F along the axial direction of the pole post 2, and the value range of F is 800 N ≤ F ≤ 1500 N. S, σ and F satisfy the following condition: σ × S > 1.2 F.

[0045] This invention, through the design of the riveting block 1 with a first through hole 101 and a second through hole 102 of different sizes and coaxially arranged, and by fitting the main riveting section 201 and the secondary riveting section 202 of the pole post 2 into the hole respectively, and by using the first stepped surface 103 to fit with the main riveting section 201, a stable riveting structure is formed. At the same time, by limiting the relationship between the contact area S between the main riveting section 201 and the first stepped surface 103, the yield strength σ of the pole post 2 and the riveting block 1, and the axial tensile force F on the riveting block 1 (σ×S>1.2F), it is ensured that under the action of a tensile force of 800N to 1500N, the connection strength between the pole post 2 and the riveting block 1 is higher than the above tensile force. This can improve the riveting firmness between the pole post 2 and the riveting block 1, reduce the risk of the pole post 2 detaching from the riveting block 1, and thus reduce the possibility of electrolyte leakage through the gap between the pole post 2 and the riveting block 1, ensuring the safety and performance of the battery cell.

[0046] It should be noted that yield strength is the yield limit of a metallic material when it undergoes yielding, that is, the stress that resists a small amount of plastic deformation. The magnitude of yield strength is generally determined by the metallic material itself. Since the materials used to manufacture the pole post 2 and the riveting block 1 are usually 1-series aluminum, the yield strength σ of the pole post 2 and the riveting block 1 ranges from 75 MPa to 140 MPa.

[0047] It is understandable that, since the sidewall of the main riveting section 201 is in contact with the wall of the first through hole 101, the contact area S between the main riveting section 201 and the first step surface 103 in this embodiment is the same as the surface area of ​​the first step surface 103. That is, the contact area S between the main riveting section 201 and the first step surface 103 is equal to the difference between the cross-sectional area of ​​the first through hole 101 along the axial direction of the pole post 2 and the cross-sectional area of ​​the second through hole 102 along the axial direction of the pole post 2.

[0048] It should be noted that the yield strength σ can be, but is not limited to, 75 MPa, 80 MPa, 85 MPa, 90 MPa, 95 MPa, 100 MPa, 105 MPa, 110 MPa, 115 MPa, 120 MPa, 125 MPa, 130 MPa, 135 MPa, and 140 MPa. Similarly, the axial tensile force F can be, but is not limited to, 800 N, 850 N, 900 N, 950 N, 1000 N, 1050 N, 1100 N, 1150 N, 1200 N, 1250 N, 1300 N, 1350 N, 1400 N, 1450 N, and 1500 N.

[0049] According to one embodiment of the present invention, such as Figure 2 , Figure 4 as well as Figure 6As shown, the length direction of the cross-section of the pole post 2 is consistent with the length direction of the riveting block 1; the riveting block 1 is provided with a pair of welding areas 104, which are located on opposite sides of the pole post 2 in the length direction of the riveting block 1; along the length direction of the riveting block 1, the length of the riveting block 1 is L1, the length of the main riveting section 201 is L2, and the length between any welding area 104 and the main riveting section 201 is L3. The following conditions are met between L1, L2 and L3: 1 / 5≤L3 / L2≤3 / 5, 0.15≤L2 / L1≤0.3.

[0050] Specifically, in this embodiment, the welding area 104 refers to the area reserved on the upper surface of the riveting block 1 for welding with the busbar. For example... Figure 6 As shown, after the riveting block 1 is welded to the busbar, a solder mark will be formed in the welding area 104. It can be understood that the area of ​​the solder mark is less than or equal to the area of ​​the welding area 104. Specifically, it can be adjusted adaptively according to the actual overcurrent requirements of the battery cell.

[0051] Generally, the width of the riveting block 1 is relatively small. In this embodiment of the invention, the length direction of the cross-section of the pole post 2 is consistent with the length direction of the riveting block 1. On the one hand, this facilitates increasing the size of the pole post 2, giving it a larger cross-sectional area (the cross-section of the pole post 2 perpendicular to the direction of current flow inside it), thereby improving the current carrying capacity of the battery cell. On the other hand, it allows workers to quickly determine the assembly direction of the pole post 2 and the riveting block 1, reducing the probability of assembly errors and improving assembly efficiency. Secondly, a pair of welding areas 104 are provided on the riveting block 1 on opposite sides of the pole post 2, which can reserve a welding area between the riveting block 1 and the busbar. At the same time, the welding areas 104 are spaced apart from the pole post 2 to prevent the high temperature generated during the welding process from adversely affecting the riveting structure between the pole post 2 and the riveting block 1. Furthermore, by defining the proportional relationship between L1, L2, and L3, this embodiment of the invention not only ensures sufficient operating space when welding the riveting block 1 to the busbar, improving the convenience and accuracy of welding and guaranteeing welding quality, but also effectively balances the stress distribution of the overall structure of the riveting block 1, enhances the stability of the connection between the pole post 2 and the riveting block 1, and enables the cell cover assembly to maintain good performance and reliability when subjected to external forces and current loads, extending the service life of the assembly and reducing the risk of cell failure due to structural problems.

[0052] Understandably, if L2 / L1 is too small, it means the length of the rivet block L1 is too long and the length of the main rivet section 201 L2 is too small, reducing the effective contact area between them. Therefore, when the rivet block 1 is subjected to tension, the contact between the pole post 2 and the rivet block 1 is prone to loosening, leading to leakage. Conversely, if L2 / L1 is too large, it means the length of the rivet block L1 is too small and the length of the main rivet section 201 L2 is too large. While this increases the contact area between the pole post 2 and the rivet block 1, it reduces the area of ​​the welding area 104, affecting the welding strength between the rivet block 1 and the busbar. Similarly, if L3 / L2 is too small, it means the distance between the welding area 104 and the pole post 2 is less than the preset range. During the welding process between the busbar and the rivet block 1, the welding fixture may interfere with the pole post 2, causing damage to the pole post 2's structure. If L3 / L2 is too large, it means that the distance between the welding area 104 and the pole post 2 is greater than the preset range value. In this case, the connection between the pole post 2 and the riveting block 1 is prone to greater stress concentration due to the excessively long force transmission path. Specifically, when the busbar is subjected to external force after welding with the welding area 104, the long distance makes it impossible for the force to be evenly distributed when it is transmitted to the connection between the pole post 2 and the riveting block 1. This can easily generate large shear forces or bending moments at the edge of the main riveting section 201, thereby reducing the stability and reliability of the connection structure and increasing the risk of the pole post 2 loosening or even detaching from the riveting block 1.

[0053] It should be noted that, in order to introduce current from the outside into the battery cell or to draw current out from the inside of the battery cell, it is currently necessary to weld the riveting block 1 to the busbar. However, during the battery cell manufacturing process or use, the busbar, as a conductive component, will be subjected to dynamic loads such as vibration and impact. Therefore, the axial tensile force F mentioned in this embodiment of the invention refers to the tensile force exerted by the busbar on the surface of the riveting block 1 under the influence of the above-mentioned dynamic loads.

[0054] It should be noted that, in this embodiment, the values ​​of L3 / L2 can be, but are not limited to, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, and 0.6. Similarly, the values ​​of L2 / L1 can be, but are not limited to, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29, and 0.30.

[0055] According to one embodiment of the present invention, S, L1, L2, and L3 satisfy 9mm. 2 ≤S≤12mm 2 32mm≤L1≤65mm, 8.5mm≤L2≤15mm, 2mm≤L3≤10mm. In this embodiment of the invention, S is controlled at 9mm. 2 Up to 12mm2 To ensure sufficient contact area between the pole post 2 and the main riveting section 201 of the riveting block 1, meeting the strength requirement of "σ×S>1.2F", and improving the tensile strength of the connection between the pole post 2 and the riveting block 1; the setting of L1 from 32mm to 65mm and L2 from 8.5mm to 15mm ensures that the riveting block 1 has a reasonable size to accommodate the pole post 2, and that the length of the main riveting section 201 is adapted to the riveting block 1, optimizing the force transmission path and avoiding insufficient connection strength due to improper length ratio; the value of L3 is 2mm to 10mm, so that the welding area 104 and the main riveting section 201 maintain a safe and easy-to-operate distance, which can prevent thermal damage to the riveting structure of the pole post 2 during welding, and also reserve sufficient space for welding fixtures, improving assembly efficiency and welding quality.

[0056] It should be noted that, in this embodiment, the value of S can be, but is not limited to, 9mm. 2 9.5mm 2 10mm 2 10.5mm 2 11mm 2 11.5mm 2 12mm 2 Similarly, the values ​​of L1 can be, but are not limited to, 32mm, 35mm, 38mm, 40mm, 44mm, 47mm, 49mm, 50mm, 51mm, 53mm, 56mm, 58mm, 60mm, 61mm, 62mm, 63mm, 64mm, and 65mm. The values ​​of L2 can be, but are not limited to, 8.5mm, 9mm, 9.5mm, 10mm, 10.5mm, 11mm, 11.5mm, 12mm, 12.5mm, 13mm, 13.5mm, 14mm, 14.5mm, and 15mm. The values ​​of L3 can be, but are not limited to, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, 6mm, 6.5mm, 7mm, 7.5mm, 8mm, 8.5mm, 9mm, 9.5mm, and 10mm.

[0057] According to one embodiment of the present invention, a pair of welding areas 104 are centrally symmetrically arranged about the center of the pole post 2. This centrally symmetrical arrangement of the pair of welding areas 104 about the center of the pole post 2 ensures that after the busbar is welded to the riveting block 1, the pole post 2 experiences uniform stress on both sides, avoiding stress concentration caused by unilateral stress. This improves the overall structural stability of the cell cover assembly and reduces the risk of loosening or deformation at the connection between the pole post 2 and the riveting block 1. It is understood that the centrally symmetrical arrangement of the pair of welding areas 104 about the center of the pole post 2 means that the distances between the two welding areas 104 and the corresponding sides of the main riveting section 201 are equal.

[0058] According to one embodiment of the present invention, the pole post 2 further includes a limiting section 203 connected to the secondary riveting section 202. Along the axial direction of the pole post 2, the limiting section 203 is located outside the second through hole 102 and is in contact with the lower surface of the riveting block 1. By having the limiting section 203 in contact with the lower surface of the riveting block 1, the axial movement of the pole post 2 can be restricted, ensuring that the main riveting section 201 and the secondary riveting section 202 can correspond to the first through hole 101 and the second through hole 102, respectively. In this way, it can be ensured that the pole post 2 deforms uniformly along its radial direction during the riveting process, and irregular deformation of the riveting block 1 due to excessive local stress can be avoided.

[0059] According to one embodiment of the present invention, such as Figure 1 , Figure 2 , Figure 3 as well as Figure 5 As shown, the end of the limiting segment 203 away from the riveting block 1 is provided with a pole post base 204. The central axis of the pole post 2 is collinear with the central axis of the pole post base 204, and the central axis of the pole post 2 is collinear with the central axis of the riveting block 1. To meet the welding requirements of the battery cell tabs, the eccentricity of the tabs cannot be large or small. Therefore, in a battery cell with a dual pole post 2 design, a portion of the pole post base 204 of one pole post 2 usually cannot be welded to the tab. Thus, it is necessary to increase the length of the pole post base 204 of the other pole post 2 to ensure the current carrying capacity of the battery cell. However, the unused portion of the pole post base 204 and the extended portion of the pole post base 204 will lead to a decrease in material utilization and an increase in production costs. In addition, since the two pole posts 2 need to be spaced apart from each other in a battery cell with a dual pole post 2 design, the pole post 2 must be eccentric relative to the pole post base 204. Based on this, in this embodiment of the invention, the central axis of the pole post 2 is set to be collinear with the central axis of the pole post base 204. This not only optimizes the current conduction path and avoids performance loss and structural hazards caused by eccentricity, but also eliminates the need to lengthen the pole post base 204 by designing a single pole post 2, thereby improving material utilization and reducing production costs. While meeting the requirements of cell overcurrent capacity and tab welding, it also improves the overall safety, reliability and economy of the cell.

[0060] Furthermore, in this embodiment of the invention, the central axis of the electrode post 2 and the central axis of the riveting block 1 are arranged collinearly, which ensures the symmetry and stability of the components, avoids uneven stress on the electrode post 2 and the riveting block 1 due to eccentric installation, and prevents problems such as loosening and deformation caused by stress concentration during high current transmission, thereby improving the reliability of the connection. In addition, the collinear design can optimize the current conduction path, allowing the current to pass through the area between the electrode post 2 and the riveting block 1 along the shortest straight line, reducing contact resistance and energy loss, stabilizing the resistance of the current-flowing area at a low level, and suppressing temperature rise during charging and discharging.

[0061] According to one embodiment of the present invention, such as Figures 1 to 3 As shown, the cross-sectional shape of the electrode post 2 is shaped like an athletic track. This embodiment of the invention designs the cross-sectional shape of the electrode post 2 as an athletic track, which allows the electrode post 2 to obtain a larger effective current-carrying area within a limited space. Compared to the traditional shape (cylindrical), it can carry a larger current, meeting the needs of fast charging of battery cells. At the same time, the shape of the athletic track optimizes the current distribution path, avoiding current concentration in localized areas, reducing resistance increases and heat generation caused by uneven current density, and ensuring temperature stability of the electrode post 2 during charging and discharging.

[0062] According to one embodiment of the present invention, such as Figure 3 and Figure 4 As shown, the riveting block 1 also has a welding hole 105 coaxially arranged with the first through hole 101. The size of the welding hole 105 is larger than the size of the first through hole 101, and the connection between the welding hole 105 and the first through hole 101 forms a second stepped surface 106. It can be understood that the welding hole 105 provides sufficient space for welding the electrode post 2 to the riveting block 1, ensuring good contact between the electrode post 2 and the riveting block 1 during the welding process. This helps improve the sealing performance of the welded part, prevents electrolyte leakage, and ensures the safety and reliability of the battery cell.

[0063] According to an embodiment of the present invention, another aspect provides a battery cell, comprising: an electrode assembly and the aforementioned battery cell cover assembly. Specifically, one end of the electrode assembly is provided with a tab; the end of the electrode post 2 in the aforementioned battery cell cover assembly away from the riveting block 1 is welded to the tab. The battery cell of the present invention includes the battery cell cover assembly as described above, possessing all the beneficial technical effects of the battery cell cover assembly, which will not be repeated here.

[0064] It should be noted that the battery cell in this embodiment can be a lithium-ion battery, sodium-ion battery, sodium-lithium-ion battery, lithium metal battery, sodium metal battery, lithium-sulfur battery, magnesium-ion battery, nickel-metal hydride battery, nickel-cadmium battery, lead-acid battery, etc., and this application embodiment is not limited to this.

[0065] In one embodiment, the electrode assembly includes a plurality of alternately arranged positive and negative electrode plates and a separator disposed between the positive and negative electrode plates.

[0066] Specifically, the positive electrode sheet includes a positive current collector and a positive active material disposed on at least one surface of the positive current collector. As an example, the positive current collector has two surfaces opposite each other in its own thickness direction, and the positive active material is disposed on either or both of the opposite surfaces of the positive current collector. As an example, the positive current collector can be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, it can be aluminum or stainless steel with a silver surface treatment, copper, aluminum, nickel, carbon electrode, carbon, nickel, or titanium, etc. The foamed metal can be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can include a polymeric material base layer and a metal layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). As an example, the positive electrode active material may include at least one of the following materials: lithium phosphate, lithium transition metal oxide, and their respective modified compounds. However, this application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium phosphate include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (such as LiMnPO4), lithium manganese phosphate and carbon composites, lithium manganese iron phosphate, and lithium manganese iron phosphate and carbon composites.

[0067] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode active material disposed on at least one surface of the negative electrode current collector. As an example, the negative electrode current collector has two surfaces opposite each other in its own thickness direction, and the negative electrode active material is disposed on either or both of the opposite surfaces of the negative electrode current collector. As an example, the negative electrode current collector may be a metal foil, a foamed metal, or a composite current collector. For example, as a metal foil, silver-treated aluminum or stainless steel, stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium, etc., may be used. The composite current collector may include a polymeric material base layer and a metal layer. The foamed metal may be foamed nickel, foamed copper, foamed aluminum, foamed alloy, or foamed carbon, etc. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymeric material substrate (such as a substrate of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). As an example, the negative electrode active material may be a negative electrode active material known in the art for use in battery cells. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate, etc.

[0068] In some embodiments, the separator is a separator membrane. This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. As an example, the main material of the separator membrane can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramics.

[0069] In some embodiments, the separator is a solid electrolyte. The solid electrolyte is disposed between the positive and negative electrodes, serving both to transport ions and to isolate the positive and negative electrodes.

[0070] It should be further noted that the electrode tabs in this embodiment include positive electrode tabs and negative electrode tabs. The positive electrode tab is formed by the portion of the positive electrode plate that does not contain active material, and the negative electrode tab is formed by the portion of the negative electrode plate that does not contain active material. The negative electrode tab and the positive electrode tab can be located together at one end of the electrode assembly or separately at both ends of the electrode assembly.

[0071] According to an embodiment of the present invention, in another aspect, a battery pack is also provided, comprising: a plurality of the above-described battery cells. The battery pack of the present invention includes the battery cells as described above, possessing all the beneficial technical effects of such battery cells, which will not be repeated here.

[0072] The effects of the present invention will be explained below with reference to some embodiments and comparative examples.

[0073] Specifically, under the condition that σ×S1>1.2F, riveting blocks 1 of different lengths with welding areas 104 and pole posts 2 of different lengths were selected. After assembling them with other components to form a battery cell, a rigorous vibration and impact test was conducted to verify the robustness of the pole post 2. The test results are shown in Table 1.

[0074] Table 1

[0075]

[0076] It can be seen that when the following conditions are met simultaneously: σ×S1>1.2F and 1 / 5≤L3 / L2≤3 / 5, 0.15≤L2 / L1≤0.3, the pole post 2 has good resistance to external forces. After verification, there is no loosening or leakage problem at the joint between the rivet block 1 and the pole post 2. However, when L2 / L1 is too large, the pole post 2 occupies a large proportion, and the welding space in the length direction of the rivet block 1 is insufficient. When L3 / L2 is too small, the welding fixture will interfere with the pole post 2 when the rivet block 1 is welded to the busbar, affecting the welding effect. When the rivet block 1 is too long and the welding area 104 is too far from the pole post 2, the rivet block 1 is subjected to a large external force during the cell vibration test, which may cause loosening and leakage at the joint between the rivet block 1 and the pole post 2.

[0077] Specifically, under the conditions of 1 / 5≤L3 / L2≤3 / 5 and 0.15≤L2 / L1≤0.3, different areas S were designed, and the electrode post 2, riveting block 1, and other components were assembled to form a battery cell. Then, a rigorous vibration and impact test was conducted to verify the robustness of the electrode post 2. The test results are shown in Table 2.

[0078] Table 2

[0079]

[0080] It can be seen that when the following conditions are met: 1 / 5≤L3 / L2≤3 / 5, 0.15≤L2 / L1≤0.3, σ×S1>1.2F must be satisfied simultaneously to ensure that the cover plate riveting block 1 will not loosen from the pole post 2 when subjected to external impact.

[0081] It should be noted that in the above experiment, EA is an abbreviation for Each, and 10EA means 10 battery cells. Furthermore, in the International System of Units (SI), 1 Pa = 1 N / m 2 Therefore, it can be deduced that 1 MPa = 10 6 Pa = 10 6 N / m 2 =10 6 N / 10 6 mm 2 =1N / mm 2 .

[0082] 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 cell cover assembly, characterized in that, include: The riveting block has a first through hole and a second through hole arranged coaxially. The size of the first through hole is larger than the size of the second through hole, and a first stepped surface is formed at the connection between the first through hole and the second through hole. The pole includes a main riveting section and a secondary riveting section. The main riveting section is located inside the first through hole and is in contact with the hole wall of the first through hole and the first stepped surface. The secondary riveting section is located inside the second through hole and is in contact with the hole wall of the second through hole. The contact area between the main riveting section and the first step surface is S; the yield strength of the pole post and the riveting block is σ, and the value range of σ is 75 MPa ≤ σ ≤ 140 MPa; the riveting block is subjected to a tensile force F along the axial direction of the pole post, and the value range of F is 800 N ≤ F ≤ 1500 N; S, σ, and F satisfy the following condition: σ × S > 1.2 F; The length direction of the cross-section of the pole post is consistent with the length direction of the riveting block; the riveting block is provided with a pair of welding areas, which are respectively located on opposite sides of the pole post in the length direction of the riveting block; along the length direction of the riveting block, the length of the riveting block is L1, the length of the main riveting segment is L2, and the length between any welding area and the main riveting segment is L3. L1, L2, and L3 satisfy the following: 1 / 5 ≤ L3 / L2 ≤ 3 / 5, 0.15 ≤ L2 / L1 ≤ 0.3; S, L1, L2, and L3 meet the 9mm requirement. 2 ≤S≤12mm 2 32mm≤L1≤65mm, 8.5mm≤L2≤15mm, 2mm≤L3≤10mm.

2. The cell cover assembly according to claim 1, characterized in that, The pair of welding zones are arranged symmetrically about the center of the pole.

3. The cell cover assembly according to claim 1, characterized in that, The pole post also includes a limiting section connected to the secondary riveting section. Along the axial direction of the pole post, the limiting section is located outside the second through hole and is in contact with the lower surface of the riveting block.

4. The cell cover assembly according to claim 3, characterized in that, The end of the limiting segment away from the riveting block is provided with a pole post base, the central axis of the pole post is collinear with the central axis of the pole post base, and the central axis of the pole post is collinear with the central axis of the riveting block.

5. The cell cover assembly according to any one of claims 1 to 4, characterized in that, The cross-sectional shape of the pole is shaped like an athletic track.

6. The cell cover assembly according to any one of claims 1 to 4, characterized in that, The riveting block is also provided with a welding hole coaxially arranged with the first through hole. The size of the welding hole is larger than the size of the first through hole, and the connection between the welding hole and the first through hole forms a second stepped surface.

7. A battery cell, characterized in that, include: The pole assembly has a pole tab at one end; The cell cover assembly according to any one of claims 1 to 6, wherein the end of the electrode post away from the riveting block is welded to the electrode tab.

8. A battery pack, characterized in that, include: The battery cell according to multiple claims 7.

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