Battery cell cover plate assembly, battery cell and battery pack

Abstract

The invention relates to the technical field of batteries, and discloses a battery cell cover plate assembly, a battery cell and a battery pack. The battery cell cover plate assembly comprises a riveting block which is provided with a first through hole and a second through hole which are coaxially arranged, the size of the first through hole is larger than that of the second through hole, and a first step surface is formed at the joint of the first through hole and the second through hole; the pole comprises a main riveting section and a secondary riveting section, the main riveting section is located in the first through hole and attached to the hole wall of the first through hole and the first step surface, and the secondary riveting section is located in the second through hole and attached to the hole wall of the second through hole; the attaching area of the main riveting section and the first step surface is S, the yield strength of the pole and the riveting block is sigma, and the value range of sigma is 75 Mpa < = sigma < = 140 Mpa; the pulling force applied to the riveting block along the axial direction of the pole is F, and the value range of F is that F is more than or equal to 800N and less than or equal to 1500N; s, sigma and F meet the condition that sigma * S is greater than 1.2 F. According to the invention, the structural stability and reliability of the cell cover plate assembly are improved by limiting the relationship among S, sigma and F.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a battery cover assembly, a battery cell and a battery pack. Background Art

[0002] The battery cell cover assembly is generally composed of a pole, a rivet block, a plain aluminum sheet, an upper plastic, a lower plastic, a sealing ring, etc. Among them, the sealing ring, the lower plastic, the plain aluminum sheet, the upper plastic, and the rivet block are sequentially passed through the pole, and the pole head is squeezed by a punch. After the pole material (such as copper, aluminum) is squeezed and deformed by its own fluidity, the battery cell cover assembly is riveted together, and laser welding is used to fix it again at the junction of the pole and the rivet block. However, during the subsequent preparation process of the battery cell or during use, the rivet block will be subjected to a force that pulls the rivet block away from the pole, so the rivet block will fall off the pole, causing the battery cell to leak, affecting the safety of the battery cell. Summary of the Invention

[0003] In view of this, the present invention provides a battery cover assembly, a battery cell and a battery pack to solve the problem that the rivet block is easily separated from the pole under the action of tension, resulting in battery cell leakage.

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

[0005] The riveting block is provided with 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 step surface is formed at the connection between the first through hole and the second through hole;

[0006] The pole comprises a primary riveted section and a secondary riveted section, wherein the primary riveted section is located in the first through hole and is in contact with the hole wall of the first through hole and the first step surface, and the secondary riveted section is located in the second through hole and is in contact with the hole wall of the second through hole;

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

[0008] Beneficial effects: The present invention designs the rivet block to have a first through hole and a second through hole of different sizes and coaxially arranged, and makes the main riveted section and the secondary riveted section of the pole respectively adapted and embedded, and utilizes the first step surface to fit with the main riveted section to form a stable riveted structure; at the same time, by limiting the relationship between the fitting area S of the main riveted section and the first step surface, the yield strength σ of the pole and the riveted block, and the axial tensile force F exerted on the riveted block (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 and the riveted block is higher than the above-mentioned tensile force, which can improve the riveting firmness of the pole and the riveted block, reduce the risk of the pole detaching from the riveted block, and further reduce the possibility of electrolyte leakage through the gap between the pole and the riveted block, thereby ensuring the safety and performance of the battery cell.

[0009] In an optional embodiment, the length direction of the cross-section of the pole is consistent with the length direction of the riveted block; the riveted block is provided with a pair of welding areas, and the pair of welding areas are respectively located on opposite sides of the pole in the length direction of the riveted block; along the length direction of the riveted block, the length of the riveted block is L1, the length of the main riveted section is L2, the length between any one of the welding areas and the main riveted section is L3, and the following conditions are satisfied among L1, L2 and L3: 1 / 5≤L3 / L2≤3 / 5, 0.15≤L2 / L1≤0.3.

[0010] Beneficial Effects: Generally, the width of the rivet block is relatively small. The present invention aligns the length of the cross-section of the pole with that of the rivet block. This, on the one hand, facilitates increasing the size of the pole, allowing the pole to have a larger cross-section (the cross-section of the pole perpendicular to the direction of current flow within it), thereby improving the current capacity of the battery cell. On the other hand, it facilitates workers to determine the assembly direction of the pole and the rivet block in a short time, reducing the probability of assembly errors and improving assembly efficiency. Secondly, a pair of welding areas are provided on opposite sides of the pole on the rivet block. This not only reserves welding areas for the rivet block and the busbar, but also maintains an appropriate spacing between the welding areas and the pole, preventing the high temperature generated during welding from adversely affecting the riveted structure of the pole and the rivet block. In addition, the present invention not only ensures sufficient operating space when welding the rivet block and the busbar, improves the convenience and accuracy of welding, and ensures welding quality by limiting the proportional relationship between L1, L2 and L3; it can also effectively balance the force distribution of the overall structure of the rivet block, enhance the stability of the connection between the pole and the rivet block, and enable the battery cover assembly to maintain good performance and reliability when subjected to external force and current load, thereby extending the service life of the assembly and reducing the risk of battery cell failure due to structural problems.

[0011] In an optional embodiment, S, L1, L2 and L3 meet 9mm 2 ≤S≤12mm 2, 32mm≤L1≤65mm, 8.5mm≤L2≤15mm, 2mm≤L3≤10mm.

[0012] Beneficial effect: The present invention controls S to 9mm 2 Up to 12mm 2 , ensuring that the main riveted section of the pole and the riveted block has sufficient contact area to meet the strength requirement of "σ×S>1.2F" and improve the tensile strength performance of the connection between the pole and the riveted block; L1 is set at 32mm to 65mm and L2 is set at 8.5mm to 15mm, which not only ensures that the riveted block has a reasonable size to accommodate the pole, but also makes the length of the main riveted section adapt to the riveted block, optimizes the force conduction path, and avoids insufficient connection strength due to improper length ratio; L3 is set at 2mm to 10mm, so that the welding area and the main riveted section maintain a safe and easy-to-operate distance, which can not only prevent thermal damage to the pole riveted structure during welding, but also reserve sufficient space for welding tooling, thereby improving assembly efficiency and welding quality.

[0013] In an optional embodiment, a pair of the welding areas are arranged in centrosymmetry with respect to the center of the pole.

[0014] Beneficial effect: The present invention arranges a pair of welding areas in a centrally symmetrical manner about the center of the pole, so that after the busbar and the rivet block are welded, the two sides of the pole are subjected to uniform force, avoiding stress concentration caused by unilateral force, thereby improving the stability of the overall structure of the battery cover assembly and reducing the risk of loosening and deformation at the connection between the pole and the rivet block.

[0015] In an optional embodiment, the pole further includes a limiting section connected to the secondary riveted section, and along the axial direction of the pole, the limiting section is located outside the second through hole and fits against the lower surface of the riveted block.

[0016] Beneficial effect: The present invention fits the limiting section with the lower surface of the rivet block, which can limit the axial movement of the pole and ensure that the main riveted section and the secondary riveted section can correspond to the first through hole and the second through hole respectively. In this way, it can be ensured that the pole is uniformly deformed along its radial direction during the riveting process, avoiding irregular deformation of the riveted block due to excessive local force.

[0017] In an optional embodiment, a pole base is provided at one end of the limiting section away from the riveted block, the central axis of the pole is collinear with the central axis of the pole base, and the central axis of the pole is collinear with the central axis of the riveted block.

[0018] Beneficial effect: In order 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 bipolar design, the portion of the pole base of one of the poles cannot usually be welded to the tabs. Therefore, it is necessary to increase the length of the pole base of the other pole to ensure the overcurrent capacity of the battery cell. However, the unused portion of the pole base and the extended portion of the pole base will lead to a decrease in material utilization and an increase in production costs. In addition, since the two poles need to be separated by a certain distance from each other in a battery cell with a bipolar design, the poles must be an eccentric structure relative to the pole base. Based on this, the present invention arranges the central axis of the pole and the central axis of the pole base in a colinear manner, which not only optimizes the current conduction path and avoids performance loss and structural hidden dangers caused by eccentricity, but also the single-pole design does not require an additional extension of the pole base, thereby improving material utilization and reducing production costs. While meeting the overcurrent capacity and tab welding requirements of the battery cell, the overall safety, reliability and economy of the battery cell are improved.

[0019] The present invention places the central axis of the pole and the central axis of the riveted block collinearly, ensuring assembly symmetry and stability. This avoids uneven force on the pole and riveted block due to eccentric installation, preventing loosening and deformation caused by stress concentration during high-current transmission, and improving connection reliability. Furthermore, the collinear design optimizes the current conduction path, allowing current to flow along the shortest straight line between the pole and the riveted block, reducing contact resistance and energy loss, keeping the resistance of the current-carrying area stable at a low level, and suppressing temperature rise during charging and discharging.

[0020] In an optional embodiment, the cross-section of the pole is in the shape of an athletic track.

[0021] Beneficial effects: The present invention designs the cross-section of the pole into the shape of an athletic track, which enables the pole to obtain a larger effective flow area in a limited space. Compared with the traditional shape (cylindrical), it can carry larger currents, 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 from being concentrated in a local area, reduces the resistance increase and heat generation problems caused by uneven current density, and ensures that the temperature of the pole is stable during the charging and discharging process.

[0022] In an optional embodiment, the riveting block is further 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 a second step surface is formed at the connection between the welding hole and the first through hole.

[0023] Beneficial effects: The welding hole provides sufficient space for welding the pole and the riveted block, ensuring good contact between the pole and the riveted block during the welding process, helping to improve the sealing performance of the welding part, preventing electrolyte leakage, and ensuring the safety and reliability of the battery cell.

[0024] In a second aspect, the present invention further provides a battery cell, comprising:

[0025] The pole group has a pole ear at one end;

[0026] In the above-mentioned battery cell cover plate assembly, one end of the pole away from the rivet block is welded to the pole 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] In a third aspect, the present invention further provides a battery pack comprising: a plurality of the above-mentioned 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 Schematic diagram of the assembly of the riveted block and the pole in an embodiment of the present invention;

[0032] Figure 2 for Figure 1 sectional view of

[0033] Figure 3 for Figure 1 Exploded diagram;

[0034] Figure 4 for Figure 1 Cross-sectional view of the middle riveting block;

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

[0036] Figure 6 This is a top view of the cell cover assembly after a weld mark is formed in the welding area of ​​the embodiment of the present invention.

[0037] Description of reference numerals:

[0038] 1. Riveting block; 101. First through hole; 102. Second through hole; 103. First step surface; 104. Welding area; 105. Welding hole; 106. Second step surface; 2. Pole; 201. Primary riveting section; 202. Secondary riveting section; 203. Position limiting section; 204. Pole base. DETAILED DESCRIPTION

[0039] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative efforts shall fall within the scope of protection of the present invention.

[0040] To address the problem that the riveted block is easily separated from the pole under the action of tension, resulting in leakage of the battery cell, the present invention provides a battery cell cover assembly, a battery cell and a battery pack.

[0041] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0042] According to an embodiment of the present invention, on the one hand, Figures 1 to 5 As shown, a battery cell cover assembly is provided, including: a riveted block 1 and a pole 2.

[0043] Specifically, the riveting block 1 is provided with a first through hole 101 and a second through hole 102 which are coaxially arranged. The size of the first through hole 101 is larger than that of the second through hole 102. A first step surface 103 is formed at the connection between the first through hole 101 and the second through hole 102. The pole 2 includes a main riveted section 201 and a secondary riveted section 202. The main riveted 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 step surface 103. The secondary riveted 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 riveted section 201 and the first step surface 103 is S, the yield strength of the pole 2 and the riveted block 1 is σ, and the value range of σ is 75 MPa ≤ σ ≤ 140 MPa; the tensile force applied to the riveted block 1 along the axis of the pole 2 is F, and the value range of F is 800 N ≤ F ≤ 1500 N; S, σ, and F satisfy: σ × S > 1.2F.

[0045] In the embodiment of the present invention, the rivet block 1 is designed to have a first through hole 101 and a second through hole 102 of different sizes and coaxially arranged, and the primary rivet section 201 and the secondary rivet section 202 of the pole 2 are respectively adapted and embedded, and the first step surface 103 is used to fit with the primary rivet section 201 to form a stable riveted structure. At the same time, by limiting the relationship between the fitting area S between the primary rivet section 201 and the first step surface 103, the yield strength σ of the pole 2 and the rivet block 1, and the axial tensile force F applied to the rivet block 1 (σ×S>1.2F), it is ensured that under a tensile force of 800N to 1500N, the connection strength between the pole 2 and the rivet block 1 is greater than the above tensile force, which can improve the riveting firmness of the pole 2 and the rivet block 1, reduce the risk of the pole 2 detaching from the rivet block 1, and further reduce the possibility of electrolyte leakage through the gap between the pole 2 and the rivet block 1, thereby ensuring the safety and performance of the battery cell.

[0046] It should be noted that yield strength is the yield limit of a metal material when it yields, that is, the stress that resists minimal plastic deformation. The yield strength is generally determined by the metal material itself. Since the current material used to make the pole 2 and the riveted block 1 is generally 1 series aluminum, the yield strength σ of the pole 2 and the riveted block 1 ranges from 75 MPa to 140 MPa.

[0047] It is understandable that, because the sidewall of the main riveted section 201 is in contact with the wall of the first through hole 101, the contact area S between the main riveted section 201 and the first step surface 103 in this embodiment is consistent with the surface area of ​​the first step surface 103. In other words, the contact area S between the main riveted 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 2 and the cross-sectional area of ​​the second through hole 102 along the axial direction of the pole 2.

[0048] It should be noted that the value of 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 value of the axial tension 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, Figure 2 、 Figure 4 as well as Figure 6As shown, the length direction of the cross section of the pole 2 is consistent with the length direction of the riveted block 1; the riveted block 1 is provided with a pair of welding areas 104, which are respectively located on opposite sides of the pole 2 in the length direction of the riveted block 1; along the length direction of the riveted block 1, the length of the riveted block 1 is L1, the length of the main riveted section 201 is L2, and the length between any welding area 104 and the main riveted section 201 is L3. The relationships among L1, L2 and L3 satisfy: 1 / 5≤L3 / L2≤3 / 5, 0.15≤L2 / L1≤0.3.

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

[0051] Generally, the width of the riveted block 1 is relatively small. In this embodiment of the present invention, the length of the cross-section of the pole 2 is aligned with the length of the riveted block 1. This, on the one hand, facilitates increasing the size of the pole 2, giving the pole 2 a larger cross-section (the cross-section of the pole 2 perpendicular to the direction of current flow within it), thereby improving the current capacity of the battery cell. On the other hand, it facilitates workers to quickly determine the assembly direction of the pole 2 and the riveted block 1, reducing the probability of assembly errors and improving assembly efficiency. Secondly, a pair of welding areas 104 are provided on the riveted block 1 on opposite sides of the pole 2, reserving areas for welding the riveted block 1 to the busbar. The welding areas 104 are spaced apart from the pole 2 to prevent the high temperatures generated during welding from adversely affecting the riveted structure between the pole 2 and the riveted block 1. In addition, the embodiment of the present invention not only ensures sufficient operating space when welding the rivet block 1 to the busbar, improves the convenience and accuracy of welding, and ensures the welding quality by limiting the proportional relationship between L1, L2 and L3, but also effectively balances the force distribution of the overall structure of the rivet block 1, enhances the stability of the connection between the pole 2 and the rivet block 1, and enables the battery cover assembly to maintain good performance and reliability when subjected to external force and current load, thereby extending the service life of the assembly and reducing the risk of battery cell failure due to structural problems.

[0052] It is understood that if L2 / L1 is too small, it means that the length of the rivet block L1 is too long and the length L2 of the main rivet section 201 is too small, reducing the effective contact area between the two. Therefore, when the rivet block 1 is subjected to tension, the contact between the pole 2 and the rivet block 1 is likely to loosen, resulting in leakage. If L2 / L1 is too large, it means that the length of the rivet block L1 is too small and the length L2 of the main rivet section 201 is too large. Although this can increase the contact area between the pole 2 and the rivet block 1, it will reduce 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 that the distance between the welding area 104 and the pole 2 is less than the preset range. During the welding process between the busbar and the rivet block 1, the welding tooling may interfere with the pole 2, causing damage to the pole 2's own structure. If L3 / L2 is too large, it means that the distance between the welding area 104 and the pole 2 is greater than the preset range. In this case, the connection between the pole 2 and the riveted 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 being welded to the welding area 104, the long distance prevents the force from being evenly distributed when it is transmitted to the connection between the pole 2 and the riveted block 1. This can easily generate large shear forces or bending moments at the edges of the main riveted section 201, thereby reducing the stability and reliability of the connection structure and increasing the risk of the pole 2 loosening or even detaching from the riveted block 1.

[0053] It should be noted that to conduct current from the outside into the battery cell or to conduct current from the inside of the battery cell, it is currently necessary to weld the rivet block 1 to the busbar. However, during the battery cell preparation process or use, the busbar, as a conductive component, will be subjected to dynamic loads such as vibration and impact. Therefore, the axial tension F mentioned in the embodiments of the present invention refers to the pulling force exerted by the busbar on the surface of the rivet block 1 under the influence of such dynamic loads.

[0054] It should be noted that in this embodiment, the value of L3 / L2 can be, but is not limited to, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, and 0.6. Similarly, the value of L2 / L1 can be, but is 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 meet the requirements of 9 mm. 2 ≤S≤12mm 2 , 32mm≤L1≤65mm, 8.5mm≤L2≤15mm, 2mm≤L3≤10mm. In the embodiment of the present invention, S is controlled at 9mm 2 Up to 12mm2 , ensuring that there is sufficient contact area between the pole 2 and the main riveted section 201 of the riveted block 1, meeting the strength requirement of "σ×S>1.2F", and improving the tensile strength performance of the connection between the pole 2 and the riveted block 1; L1 is set to 32mm to 65mm and L2 is set to 8.5mm to 15mm, which not only ensures that the riveted block 1 has a reasonable size to accommodate the pole 2, but also makes the length of the main riveted section 201 adapt to the riveted block 1, optimizes the force conduction path, and avoids insufficient connection strength due to improper length ratio; L3 is set to 2mm to 10mm, so that the welding area 104 and the main riveted section 201 maintain a safe and easy-to-operate distance, which can not only prevent thermal damage to the riveted structure of the pole 2 during welding, but also reserve sufficient space for welding tooling, thereby improving assembly efficiency and welding quality.

[0056] It should be noted that the value of S in this embodiment 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 value of L1 can be, but is not limited to, 32mm, 35mm, 38mm, 40mm, 44mm, 47mm, 49mm, 50mm, 51mm, 53mm, 56mm, 58mm, 60mm, 61mm, 62mm, 63mm, 64mm, and 65mm. The value of L2 can be, but is 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 value of L3 can be, but is 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 2. This embodiment of the present invention arranges the pair of welding areas 104 centrally symmetrically about the center of the pole 2. This ensures that after the busbar is welded to the rivet block 1, stress is evenly applied to both sides of the pole 2, avoiding stress concentration caused by unilateral stress. This improves the overall structural stability of the battery cell cover assembly and reduces the risk of loosening or deformation at the connection between the pole 2 and the rivet block 1. It will be understood that the centrally symmetrical arrangement of the pair of welding areas 104 about the center of the pole 2 means that the distances between the two welding areas 104 and the corresponding sides of the main rivet section 201 are equal.

[0058] According to one embodiment of the present invention, the pole 2 further includes a limiting section 203 connected to the secondary riveted section 202. Along the axial direction of the pole 2, the limiting section 203 is located outside the second through-hole 102 and abuts against the lower surface of the riveted block 1. In this embodiment of the present invention, the limiting section 203 abuts against the lower surface of the riveted block 1, thereby limiting the axial movement of the pole 2 and ensuring that the primary riveted section 201 and the secondary riveted section 202 correspond to the first through-hole 101 and the second through-hole 102, respectively. This ensures that the pole 2 deforms uniformly along its radial direction during the riveting process, preventing irregular deformation of the riveted block 1 due to excessive local force.

[0059] According to one embodiment of the present invention, Figure 1 、 Figure 2 、 Figure 3 as well as Figure 5 As shown, a pole base 204 is provided at one end of the limiting section 203 away from the riveted block 1, and the central axis of the pole 2 is arranged in a collinear manner with the central axis of the pole base 204, and the central axis of the pole 2 is arranged in a collinear manner with the central axis of the riveted block 1. In order to meet the welding requirements of the battery cell tab, the eccentricity of the tab cannot be large or small. Therefore, in a battery cell designed with a bipolar post 2, part of the pole base 204 of one pole 2 is usually unable to be welded to the tab, so it is necessary to increase the length of the pole base 204 of the other pole 2 to ensure the current capacity of the battery cell. However, the unused part of the pole base 204 and the extended part of the pole base 204 will lead to a decrease in material utilization and an increase in production costs. In addition, since the two poles 2 need to be separated by a distance from each other in a battery cell designed with a bipolar post 2, the pole 2 must be an eccentric structure relative to the pole base 204. Based on this, the embodiment of the present invention sets the central axis of the pole 2 and the central axis of the pole base 204 to be colinear, which not only optimizes the current conduction path and avoids performance loss and structural hidden dangers caused by eccentricity, but also the single pole 2 design does not require additional lengthening of the pole base 204, thereby improving material utilization and reducing production costs. While meeting the battery cell's overcurrent capacity and tab welding requirements, it improves the overall safety, reliability and economy of the battery cell.

[0060] Furthermore, the collinear arrangement of the central axis of the pole 2 and the central axis of the riveted block 1 ensures assembly symmetry and stability, avoids uneven stress on the pole 2 and riveted block 1 due to eccentric installation, and prevents loosening and deformation caused by stress concentration during high current transmission, thereby improving connection reliability. Furthermore, the collinear design optimizes the current conduction path, allowing current to flow along the shortest straight line between the pole 2 and the riveted block 1, reducing contact resistance and energy loss, keeping the resistance of the current flowing through the area at a stable low level, and suppressing temperature rise during charging and discharging.

[0061] According to one embodiment of the present invention, Figures 1 to 3 As shown, the cross-section of the pole 2 is in the shape of an athletic track. In the embodiment of the present invention, the cross-section of the pole 2 is designed to be in the shape of an athletic track, which can enable the pole 2 to obtain a larger effective 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 from being concentrated in a local area, reduces the resistance increase and heat generation problems caused by uneven current density, and ensures that the temperature of the pole 2 is stable during the charging and discharging process.

[0062] According to one embodiment of the present invention, Figure 3 and Figure 4 As shown, the riveted block 1 is further provided with a welding hole 105 coaxially arranged with the first through hole 101. The size of the welding hole 105 is larger than that of the first through hole 101, and a second step surface 106 is formed at the connection between the welding hole 105 and the first through hole 101. It can be understood that the welding hole 105 provides sufficient space for welding the electrode 2 to the riveted block 1, ensuring good contact between the electrode 2 and the riveted block 1 during the welding process, helping to improve the sealing performance of the welding part, preventing electrolyte leakage, and ensuring the safety and reliability of the battery cell.

[0063] According to another aspect of an embodiment of the present invention, a battery cell is provided, comprising: an electrode group and the aforementioned cell cover assembly. Specifically, a tab is provided at one end of the electrode group; the end of the electrode post 2 in the cell cover assembly, distal from the rivet block 1, is welded to the tab. The battery cell of this embodiment of the present invention, including the aforementioned cell cover assembly, exhibits all the beneficial technical effects of the cell cover assembly and will not be further elaborated here.

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

[0065] In one embodiment, the electrode group in this embodiment includes a plurality of alternating positive electrode sheets and negative electrode sheets and separators arranged between the positive electrode sheets and the negative electrode sheets.

[0066] Specifically, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two surfaces opposing each other in its thickness direction, and the positive electrode active material is disposed on either or both of the two opposing surfaces of the positive electrode current collector. For example, the positive electrode current collector may be a metal foil, a metal foam, or a composite current collector. For example, the metal foil may include silver-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector may include a polymer base layer and a metal layer. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.) on a polymer substrate (such as a substrate made 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-containing phosphates, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional 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-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[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. For example, the negative electrode current collector has two surfaces opposing each other in its thickness direction, and the negative electrode active material is disposed on either or both of the opposing surfaces of the negative electrode current collector. For example, the negative electrode current collector may be a metal foil, metal foam, or a composite current collector. For example, the metal foil may include silver-treated aluminum or stainless steel, copper, aluminum, nickel, carbon electrodes, carbon, nickel, or titanium. The composite current collector may include a polymer base layer and a metal layer. The metal foam may include nickel foam, copper foam, aluminum foam, alloy foam, or carbon foam. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy, etc.) on a polymer substrate (such as a substrate made of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polystyrene, polyethylene, etc.). For example, the negative electrode active material may be a negative electrode active material commonly known in the art for 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, lithium titanate, and the like.

[0068] In some embodiments, the separator is a separator. This application does not specifically limit the type of separator; any known porous separator with good chemical and mechanical stability can be used. For example, the separator can be made primarily of at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic.

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

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

[0071] According to another aspect of an embodiment of the present invention, a battery pack is provided, comprising: a plurality of the above-mentioned battery cells. The battery pack of the embodiment of the present invention comprises the above-mentioned battery cells and has all the beneficial technical effects of the battery cells, which will not be described in detail here.

[0072] The effects of the present invention are described below with reference to some embodiments and comparative examples.

[0073] Specifically, under the condition that σ×S1>1.2F is satisfied, rivet blocks 1 of varying lengths and provided with welding zones 104 and poles 2 of varying lengths were selected. These were then assembled with other components to form a battery cell, and then subjected to rigorous vibration and shock testing to verify the robustness of the poles 2. The test results are shown in Table 1.

[0074] Table 1

[0075]

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

[0077] Specifically, when 1 / 5 ≤ L3 / L2 ≤ 3 / 5 and 0.15 ≤ L2 / L1 ≤ 0.3, different areas S were designed. After assembling the pole 2, rivet block 1, and other components to form a battery cell, rigorous vibration and shock testing was performed to verify the robustness of the pole 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 also be met to ensure that the cover plate rivet block 1 will not loosen from the pole 2 column when subjected to external force impact.

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

[0082] Although the embodiments of the present invention have been described with reference to the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. Such modifications and variations are all within the scope defined by the appended claims.

Claims

1. A battery cover assembly, characterized in that: include: The riveting block is provided with 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 step surface is formed at the connection between the first through hole and the second through hole; The pole comprises a primary riveted section and a secondary riveted section, wherein the primary riveted section is located in the first through hole and is in contact with the hole wall of the first through hole and the first step surface, and the secondary riveted section is located in the second through hole and is in contact with the hole wall of the second through hole; The contact area between the main riveted section and the first step surface is S, the yield strength of the pole and the riveted block is σ, and the value range of σ is 75 MPa ≤ σ ≤ 140 MPa; the tensile force applied to the riveted block along the axis of the pole is F, and the value range of F is 800 N ≤ F ≤ 1500 N; S, σ and F satisfy: σ × S > 1.2F.

2. The battery cover assembly according to claim 1, characterized in that: The length direction of the cross section of the pole is consistent with the length direction of the riveted block; the riveted block is provided with a pair of welding areas, and the pair of welding areas are respectively located on opposite sides of the pole in the length direction of the riveted block; along the length direction of the riveted block, the length of the riveted block is L1, the length of the main riveted section is L2, and the length between any one of the welding areas and the main riveted section is L3, and the relationship between L1, L2 and L3 satisfies the following: 1 / 5≤L3 / L2≤3 / 5, 0.15≤L2 / L1≤0.

3.

3. The battery cover assembly according to claim 2, characterized in that: S, L1, L2 and L3 meet 9mm 2 ≤S≤12mm 2 , 32mm≤L1≤65mm, 8.5mm≤L2≤15mm, 2mm≤L3≤10mm.

4. The battery cover assembly according to claim 2, characterized in that: A pair of welding areas are centrally symmetrically arranged about the center of the pole.

5. The battery cover assembly according to claim 1, characterized in that: The pole further includes a limiting section connected to the secondary riveting section. Along the axial direction of the pole, the limiting section is located outside the second through hole and fits against the lower surface of the riveting block.

6. The battery cover assembly according to claim 5, characterized in that: A pole base is provided at one end of the limiting section away from the riveting block, the central axis of the pole is collinear with the central axis of the pole base, and the central axis of the pole is collinear with the central axis of the riveting block.

7. The battery cell cover assembly according to any one of claims 1 to 6, characterized in that: The cross section of the pole is in the shape of an athletic track.

8. The battery cell cover assembly according to any one of claims 1 to 6, characterized in that: The rivet block is further provided with a welding hole coaxially arranged with the first through hole. The size of the welding hole is larger than that of the first through hole. A second step surface is formed at the connection between the welding hole and the first through hole.

9. A battery cell, characterized in that: include: The pole group has a pole ear at one end; The battery cell cover plate assembly according to any one of claims 1 to 8, wherein the end of the pole away from the rivet block is welded to the pole tab.

10. A battery pack, characterized in that: include: A plurality of battery cells according to claim 9.

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