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 cover body provided with a first through hole, and the width of the cover body is W; the pole comprises a pole body and a pole base, and at least part of the pole body is arranged in the first through hole in a penetrating manner; a first welding mark is arranged on the surface of the side, located outside the first through hole and away from the cover body, of the pole base, the width of the first welding mark is a, the rated current of the first welding mark is I, the overcurrent coefficient of the first welding mark is sigma, the distance between the edge of the first welding mark and the corresponding edge of the pole base is b, the length of the pole base is L1, and the width of the pole base is W1, the relation among a, b and W1 meets the condition that a + 2 * b < = W1 < = W-4 mm; and a, b, I, sigma and L1 satisfy the following relation: I / (sigma * a) + 2b < = L1 < = I / (sigma * a) + 2b + 3mm. By limiting the size of the pole base and the size of the first welding mark, the reasonability of the size of the first welding mark and the size of the pole base is ensured.

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] As power batteries become increasingly common in vehicles, demand for fast charging is growing. Secondly, because batteries rely on tabs and terminals to draw current in and out of the battery, the design of the connection between the tabs and terminals is crucial. However, there is currently a mismatch between the weld mark dimensions and the terminal base, resulting in redundant terminal base designs and increased battery production costs. 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 in the prior art that the mismatch between the weld mark size between the pole tab and the pole and the rated current of the weld mark leads to a high temperature rise at the connection between the pole tab and the pole, and the design redundancy of the pole base leads to an increase in battery production costs.

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

[0005] The cover body is provided with a first through hole, and the width of the cover body is W;

[0006] A pole, comprising a pole body and a pole base disposed at one end of the pole body, wherein at least a portion of the pole body is disposed within the first through hole; a first weld mark is disposed on a surface of the pole base located outside the first through hole and away from the cover body, wherein the length and width directions of the first weld mark, the pole base, and the cover body are consistent;

[0007] The width of the first weld mark is a, the rated current of the first weld mark is I, the overcurrent coefficient of the first weld mark is σ, along the width direction or length direction of the cover body, the distance between the edge of the first weld mark and the corresponding edge of the pole base is b, the length of the pole base is L1, and the width of the pole base is W1, wherein the relationship between a, b, and W1 satisfies: a+2*b≤W1≤W-4mm; the relationship between a, b, I, σ, and L1 satisfies: I / (σ*a)+2b≤L1≤I / (σ*a)+2b+3mm.

[0008] Beneficial effect: The present invention sets a first weld mark on the side of the pole base away from the cover body, which is consistent with the length and width direction of the pole base and the cover body, and stipulates that the relationship between a, b, and W1 satisfies a+2b≤W1≤W-4mm, and the relationship between a, b, I, σ, and L1 satisfies I / (σ*a)+2b≤L1≤I / (σ*a)+2b+3mm. This not only allows the size of the first weld mark to match the rated current, optimizes the connection structure between the tab and the pole (that is, optimizes the area of ​​the first weld mark), and reduces the temperature rise at the connection between the two; it also can optimize the size of the pole base, avoid design redundancy of the pole base, reduce material usage, and thus reduce the production cost of the battery cell.

[0009] In an optional embodiment, the width a of the first weld mark is in the range of 2 mm ≤ a ≤ 6 mm, the distance b between the edge of the first weld mark and the corresponding edge of the pole base is in the range of 2 mm ≤ b ≤ 5 mm, and the flow coefficient σ of the first weld mark is in the range of 5 A / mm 2 ≤σ≤8A / mm 2 .

[0010] Beneficial effects: The present invention limits the width a of the first weld mark to between 2mm and 6mm, which can ensure that there is sufficient welding area between the tab and the pole base to ensure the reliability of the electrical connection, and can also avoid affecting the overcurrent capacity of the battery cell due to the first weld mark width being too narrow; and the edge distance b is limited to the range of 2mm to 5mm, which can not only prevent stress concentration problems in the welding part, but also prevent the solder from spreading to the edge of the pole base; and the overcurrent coefficient σ is limited to 5A / mm 2 Up to 8A / mm 2 The weld mark width can be adapted to the current flowing through it, controlling the temperature rise at the first weld mark and improving the reliability and safety of the cell cover assembly. Furthermore, since the length and width of the pole base depend on a, b, and σ, setting a, b, and σ according to these parameters can determine the optimal length L1 and width W1 of the pole base, avoiding design redundancy. This reduces material usage and lowers the production cost of the cell cover assembly while ensuring performance.

[0011] In an optional embodiment, the cover further includes a rivet block provided on a side of the cover body away from the pole base, the rivet block is provided with a second through hole coaxially arranged with the first through hole, and at least a portion of the pole body is passed through the first through hole and the second through hole; a pair of second weld marks are provided on a surface of the rivet block away from the pole base, the pair of second weld marks are respectively located on opposite sides of the second through hole in the length direction of the rivet block, and the length direction and width direction of the second through hole, the second weld mark, the rivet block and the cover body are consistent.

[0012] Beneficial Effects: By providing a rivet block on the cover body and a second through-hole coaxially arranged with the first through-hole, the present invention allows at least a portion of the pole body to be inserted into the second through-hole, facilitating subsequent riveting of the pole body and the rivet block. This allows the pole body to be more securely mounted on the cover body, reducing the likelihood of the pole body falling off the cover body due to vibration, external forces, and the like. Furthermore, a pair of second weld marks are provided on the side of the rivet block facing away from the pole base, with the length and width of the second through-hole, the second weld marks, the rivet block, and the cover body aligned. This increases the weld contact area, optimizes the current conduction path, helps reduce resistance in the connection between the rivet block and other components, and reduces heat generation at the connection. Furthermore, the symmetrically distributed second weld marks ensure even force distribution and avoid localized stress concentration.

[0013] In an optional embodiment, the rated current of the second weld mark is I', and the overcurrent coefficient of the second weld mark is γ; along the length direction of the cover body, the length of the second through hole is g, and along the width direction of the cover body, the distance between the edge of the rivet block and the corresponding edge of the cover body is c, and the distance between the edge of the second weld mark and the corresponding edge of the rivet block is d; along the length direction of the cover body, the distance between the second weld mark and the second through hole or the distance between the second weld mark and the corresponding edge of the rivet block is e; the width of the rivet block is W2, the length of the rivet block is L2, and the width of the second weld mark is W3, wherein the relationship between W2, W, and c satisfies: W2≤W-2c, the relationship between W3, W2, and d satisfies: W3≤W2-2d, and the relationship between L2, I', γ, W3, e, and g satisfies: L2≥I' / (γ*W3)+4e+g.

[0014] Beneficial effects: The present invention limits the relationship between W2, W, and c to W2≤W-2c, which not only reasonably controls the width of the rivet block and avoids the cost increase caused by the excessive size of the rivet block, but also ensures that the rivet block can be adapted and installed with the cover body; and limits the relationship between W3, W2, and d to W3≤W2-2d, which ensures the rationality of the layout of the second weld mark on the rivet block and avoids overflow due to the excessive width of the second weld mark; and limits the relationship between L2, I', γ, W3, e, and g to L2≥I' / (γ*W3)+4e+g, which can make the size of the second weld mark compatible with the rated current I', optimize the current conduction performance, and reduce the temperature rise at the second weld mark. Secondly, the present invention sets the second weld mark at a distance from the edge of the rivet block, which not only reserves operating space for the welding process and avoids the interference of solder overflow, but also releases the thermal stress and mechanical stress during the welding process, enhancing the stability and reliability of the structure.

[0015] In an optional embodiment, the value range of the flow coefficient γ of the second weld mark is 5A / mm 2 ≤γ≤8A / mm 2 The distance c between the edge of the rivet block and the corresponding edge of the cover body is in the range of 3 mm ≤ c ≤ 5 mm, the distance d between the edge of the second weld mark and the corresponding edge of the rivet block is in the range of 2.7 mm ≤ d ≤ 5 mm, and the distance e between the second weld mark and the second through hole is in the range of 3.2 mm ≤ e ≤ 5 mm.

[0016] Beneficial effect: The present invention limits the second weld flow coefficient γ to 5A / mm 2 ≤γ≤8A / mm 2 , which can ensure that the second weld print works under the appropriate current carrying capacity, which can not only meet the overcurrent requirements of the battery pack, but also avoid the waste of materials caused by overheating or too low of the second weld print due to excessive overcurrent coefficient, and optimize the current conduction efficiency; the range of the edge distance c between the rivet block and the cover body is 3mm≤c≤5mm, the range of the edge distance d between the second weld print and the rivet block is 2.7mm≤d≤5mm, and the range of the distance e between the second weld print and the second through hole is 3.2mm≤d≤5mm. On the one hand, it provides sufficient operating space for the welding process to prevent solder overflow from affecting other components. On the other hand, it can effectively release the thermal stress in the welding process, avoid structural damage caused by stress concentration, and enhance the structural stability and assembly adaptability of the battery cover assembly.

[0017] In an optional embodiment, the cross-sectional shape of the pole body is a track-and-field runway shape.

[0018] Beneficial effects: The present invention designs the cross-sectional shape of the pole into a circular runway shape or an athletics track shape, 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 athletics 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.

[0019] In an optional embodiment, the length direction and width direction of the pole body and the cover body are consistent, the pole body includes a riveted section and a limiting section, the riveted section is passed through the first through hole, and the limiting section is located outside the first through hole and the second through hole and connected to the pole base; along the width direction of the cover body, the width of the riveted section is W4, the distance between the edge of the riveted section and the corresponding edge of the riveted block is f, and the width of the limiting section is W5; the relationship between W2, W4, and f satisfies W4≤W2-2f, and the relationship between W4 and W5 satisfies W5≥W4+0.4mm.

[0020] Beneficial effects: The present invention divides the pole body into a riveted section and a limiting section, and by limiting the relationship between W2, W4, and f (W4≤W2-2f), the width of the riveted section can be reasonably controlled to ensure that it is adapted for installation with the riveted block, avoiding interference due to excessive size or insufficient connection strength due to too small size; and by limiting the relationship between W4 and W5 (W5≥W4+0.4mm), the width of the limiting section can be made greater than the width of the riveted section, thereby forming a stable limiting structure between the pole base and the riveted block, enhancing the connection stability between the pole body and the cover assembly, preventing the pole from being displaced or loosened during use, and thereby improving the overall mechanical strength and reliability of the battery cell cover assembly.

[0021] In an optional embodiment, the overcurrent coefficient of the pole body is β, and the value range of β is 8A / mm 2 ≤β≤10A / mm 2 Along the length direction of the cover body, the length of the pole body is L3, the relationship between L3, I, β, and W5 satisfies L3≥4I / (β*π*W5), and the relationship between L3 and g satisfies: g≤L3-0.4mm.

[0022] Beneficial effect: The present invention sets the β value range to 8A / mm 2 ≤β≤10A / mm 2 , which can ensure that the pole body operates under a reasonable current carrying capacity. In this way, it can meet the transmission needs of large currents and avoid overheating problems caused by insufficient overcurrent capacity. Secondly, by defining the relationship between L3, I, β, and W5, the length of the pole body can be matched with the rated current, optimizing the current conduction path, reducing resistance and temperature rise; and through the relationship between L3 and g (g≤L3-0.4mm), the length of the second through hole is guaranteed to adapt to the length of the pole body, avoiding installation interference or loose connection problems caused by improper dimensions of the two, and enhancing the assembly stability and structural reliability between the pole and the rivet block and cover body, thereby improving the overall performance and safety of the battery cell and battery pack, reducing the risk of failure, and reducing production costs.

[0023] In a second aspect, the present invention further provides a battery cell, comprising:

[0024] The pole group has a pole ear at one end;

[0025] In the above-mentioned battery cell cover plate assembly, the side of the pole base away from the cover body is welded to the pole tab to form the first weld mark.

[0026] 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.

[0027] In a third aspect, the present invention further provides a battery pack comprising: a plurality of the above-mentioned battery cells.

[0028] 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

[0029] 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.

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

[0031] Figure 2 for Figure 1 The structure diagram of the battery cover assembly shown in FIG.

[0032] Figure 3 for Figure 1 A top view of the cell cover assembly after a second weld mark is formed on the rivet block;

[0033] Figure 4 for Figure 1 The bottom view of the cell cover assembly after forming the first weld mark on the pole base is shown;

[0034] Figure 5 This is a schematic structural diagram of a pole according to an embodiment of the present invention;

[0035] Figure 6 The figure is a partial structural diagram of a battery cell according to an embodiment of the present invention.

[0036] Description of reference numerals:

[0037] 1. Cover body; 2. Pole; 201. Pole body; 2011. Riveted section; 2012. Limiting section; 202. Pole base; 3. First weld mark; 4. Riveted block; 5. Second weld mark; 6. Pole group; 601. Pole ear; 7. Lower plastic; 701. Flanged edge. DETAILED DESCRIPTION

[0038] 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.

[0039] In order to address the problem in the prior art that the size of the weld mark between the tab and the pole does not match the rated current of the weld mark, resulting in a high temperature rise at the connection between the tab and the pole, and the problem that the design redundancy of the pole base leads to an increase in battery production costs, the present invention provides a battery cover assembly, a battery cell and a battery pack.

[0040] The following combination Figures 1 to 6 , describing embodiments of the present invention.

[0041] According to an embodiment of the present invention, Figure 1 、 Figure 2 as well as Figure 4 As shown, on the one hand, a battery cell cover plate assembly is provided, including: a cover body 1 and a pole 2.

[0042] Specifically, the cover body 1 is provided with a first through hole, and the width of the cover body 1 is W; the pole 2 includes a pole body 201 and a pole base 202 arranged at one end of the pole body 201, and at least part of the pole body 201 is passed through the first through hole; the pole base 202 is located outside the first through hole and is away from the cover body 1. A first weld mark 3 is provided on the side surface, and the length direction and width direction of the first weld mark 3, the pole base 202 and the cover body 1 are consistent; the width of the first weld mark 3 is a, and the rated current of the first weld mark 3 is The flow coefficient of the first weld mark 3 is I, the flow coefficient of the first weld mark 3 is σ, the distance between the edge of the first weld mark 3 and the corresponding edge of the pole base 202 along the width direction or the length direction of the cover body 1 is b, the length of the pole base 202 is L1, and the width of the pole base 202 is W1, wherein the relationship among a, b, and W1 satisfies: a+2*b≤W1≤W-4mm; the relationship among a, b, I, σ, and L1 satisfies: I / (σ*a)+2b≤L1≤I / (σ*a)+2b+3mm.

[0043] In the embodiment of the present invention, a first weld mark 3 is provided on the side of the pole base 202 away from the cover body 1, which is consistent with the length and width directions of the pole base 202 and the cover body 1, and stipulates that the relationship between a, b, and W1 satisfies a+2b≤W1≤W-4mm, and the relationship between a, b, I, σ, and L1 satisfies I / (σ*a)+2b≤L1≤I / (σ*a)+2b+3mm. This not only allows the size of the first weld mark 3 to match the rated current, optimizes the connection structure between the tab 601 and the pole 2 (that is, optimizes the area of ​​the first weld mark 3), and reduces the temperature rise at the connection between the two; it also can optimize the size of the pole base 202, avoid design redundancy of the pole base 202, reduce material usage, and thus reduce the production cost of the battery cell.

[0044] It should be noted that the maximum width of the pole base 202 is W-4mm because the battery cover assembly also includes a lower plastic 7. Along the thickness direction of the cover body 1, the lower plastic 7 is arranged on the lower surface of the cover body 1 and is sleeved on the outside of the pole base 202. Furthermore, along the width direction of the cover body 1, the lower surfaces of the lower plastic 7 on both sides are provided with flanges 701. Among them, in the existing design, the wall thickness of the flange 701 itself is usually greater than or equal to 0.75mm, and the distance between the flange 701 and the corresponding edge of the cover body 1 is usually greater than or equal to 1.25mm. Therefore, the maximum width W1 of the pole base 202 is W-2*(1.25mm+0.75mm).

[0045] It can be understood that the length of the first weld mark 3 in this embodiment is I / (σ*a). The reason why the length of the first weld mark 3 is I / (σ*a) is because the first weld mark 3 in this embodiment is rectangular in shape, and the flow coefficient σ represents the current that can pass through the weld mark per unit cross-sectional area. Therefore, when a is the width of the first weld mark 3, the length of the first weld mark 3 in this embodiment is equal to I / (σ*a).

[0046] It should be noted that, in order to introduce current from the outside into the battery cell or to draw current out from the battery cell, it is currently necessary to weld the pole base 202 of the pole 2 to the tab 601 of the electrode group 6. Therefore, the first weld mark 3 on the pole base 202 in this embodiment is the welding mark left on the pole base 202 after the pole base 202 and the tab 601 are welded.

[0047] Furthermore, compared to directly welding the pole 2 to the tab 601, the embodiment of the present invention connects the pole 2 to the tab 601 via the pole base 202. This increases the welding contact area between the pole 2 and the tab 601, ensuring that the effective flow area of ​​the weld meets the design requirements, thereby reducing energy loss and heat generation during current transmission, and improving the charging and discharging efficiency and safety of the battery cell. Furthermore, compared to increasing the size of the pole 2, the embodiment of the present invention connects the pole 2 to the tab 601 via the pole base 202, which not only avoids the increase in material costs caused by the increased cross-sectional area of ​​the pole 2 itself, but also avoids the increased space occupied by the increased cross-sectional area of ​​the pole 2 itself.

[0048] In addition, the cover body 1 in this embodiment can be, but is not limited to, a rectangular aluminum sheet, and the cross-sectional shape of the pole base 202 in this embodiment can be, but is not limited to, a rectangle. Specifically, the cross-sectional shape of the pole base 202 refers to a cross-section of the pole base 202 perpendicular to the direction of current flow.

[0049] It should be noted that if Figure 4 As shown, in this embodiment, the length of the cover body 1 is L, and the value range of L is 90mm≤L≤215mm. In addition, in this embodiment, the width W of the cover body 1 is in the range of 14mm≤L≤22mm. In this embodiment, the value range of I is 80A≤I≤500A.

[0050] According to one embodiment of the present invention, the width a of the first weld mark 3 is in the range of 2 mm ≤ a ≤ 6 mm, the distance b between the edge of the first weld mark 3 and the corresponding edge of the pole base 202 is in the range of b ≥ 2 mm, and the flow coefficient σ of the first weld mark 3 is in the range of 5 A / mm 2 ≤σ≤8A / mm 2 In the embodiment of the present invention, the width a of the first weld mark 3 is limited to between 2 mm and 6 mm, which can ensure that there is sufficient welding area between the tab 601 and the pole base 202 to ensure the reliability of the electrical connection, and can also avoid the overcurrent capacity of the battery cell being affected by the narrow width of the first weld mark 3; and limiting the edge distance b to a range of 2 mm to 5 mm can not only prevent stress concentration problems in the welding part, but also prevent the solder from spreading to the edge of the pole base 202; and limiting the value of the overcurrent coefficient σ to 5 A / mm 2 Up to 8A / mm 2The width of the weld mark can be adapted to the current flowing through it, controlling the temperature rise at the first weld mark 3 and improving the reliability and safety of the cell cover assembly. Furthermore, since the length and width of the pole base 202 depend on a, b, and σ, setting a, b, and σ according to the aforementioned parameters can determine the optimal length L1 and width W1 of the pole base 202, avoiding design redundancy. This reduces material usage and lowers the production cost of the cell cover assembly while ensuring performance.

[0051] It is understood that the value range of a in this embodiment can be, but is not limited to, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, 5mm, 5.5mm, and 6mm. The value range of σ can be, but is not limited to, 5A / mm 2 , 5.5A / mm 2 , 6A / mm 2 , 6.5A / mm 2 , 7A / mm 2 , 7.5A / mm 2 , 8A / mm 2 .

[0052] According to one embodiment of the present invention, the cover body 1 further includes a rivet block 4 disposed on a side facing away from the pole base 202. The rivet block 4 includes a second through-hole coaxially disposed with the first through-hole, and at least a portion of the pole body 201 is disposed within the first and second through-holes. A pair of second weld marks 5 are disposed on a surface of the rivet block 4 facing away from the pole base 202. The second weld marks 5 are located on opposite sides of the second through-hole in the longitudinal direction of the rivet block 4. The second through-hole, the second weld marks 5, the rivet block 4, and the cover body 1 are aligned in both the longitudinal and width directions. In this embodiment of the present invention, by providing the rivet block 4 on the cover body 1 and providing the second through-hole coaxially disposed with the first through-hole, at least a portion of the pole body 201 is disposed within the second through-hole, thereby enabling subsequent riveting of the pole body 201 to the rivet block 4. This allows the pole body 201 to be more securely mounted on the cover body 1, reducing the possibility of the pole body 201 falling off the cover body 1 due to vibration, external forces, or the like. A pair of second weld marks 5 are provided on the side of the rivet block 4 facing away from the pole base 202, and the length and width directions of the second through hole, the second weld mark 5, the rivet block 4 and the cover body 1 are consistent. On the one hand, the welding contact area is increased, the current conduction path is optimized, and it helps to reduce the resistance of the connection between the rivet block 4 and other components and reduce the heat generation at the connection. On the other hand, the symmetrically distributed design of the second weld marks 5 can balance the force and avoid local stress concentration.

[0053] It should be noted that to achieve series and / or parallel connection between multiple battery cells, the rivet blocks 4 on two adjacent battery cell cover plate assemblies are typically connected together using a busbar. To ensure the stability of the connection between the busbar and the rivet blocks 4, ultrasonic welding is currently used. Therefore, the second weld mark 5 in this embodiment is the weld mark left on the rivet block 4 after welding the busbar.

[0054] According to one embodiment of the present invention, Figure 3 As shown, the rated current of the second weld mark 5 is I', and the overcurrent coefficient of the second weld mark 5 is γ; along the length direction of the cover body 1, the length of the second through hole is g, and along the width direction of the cover body 1, the distance between the edge of the rivet block 4 and the corresponding edge of the cover body 1 is c, and the distance between the edge of the second weld mark 5 and the corresponding edge of the rivet block 4 is d; along the length direction of the cover body 1, the distance between the second weld mark 5 and the second through hole or the distance between the second weld mark 5 and the corresponding edge of the rivet block 4 is e; the width of the rivet block 4 is W2, the length of the rivet block 4 is L2, and the width of the second weld mark 5 is W3, wherein the relationship between W2, W, and c satisfies: W2≤W-2c, the relationship between W3, W2, and d satisfies: W3≤W2-2d, and the relationship between L2, I', γ, W3, e, and g satisfies: L2≥I' / (γ*W3)+4e+g.

[0055] It should be noted that the second through hole in this embodiment is usually a stepped hole, and the size of the stepped hole decreases from top to bottom along the thickness direction of the cover body. Therefore, the length g of the second through hole in this embodiment refers to the length of the upper half of the stepped hole in the length direction of the cover body.

[0056] In this embodiment of the present invention, the relationship between W2, W, and c is limited to W2 ≤ W-2c. This not only rationally controls the width of the rivet block 4, avoiding increased costs due to an oversized rivet block 4, but also ensures that the rivet block 4 can be mounted securely on the cover body 1. Furthermore, the relationship between W3, W2, and d is limited to W3 ≤ W2-2d, ensuring the rational layout of the second weld mark 5 on the rivet block 4 and avoiding overflow due to an excessive width of the second weld mark 5. Furthermore, the relationship between L2, I', γ, W3, e, and g is limited to L2 ≥ I' / (γ*W3)+4e+g, which adapts the size of the second weld mark 5 to the rated current I', optimizes current conduction performance, and reduces temperature rise at the second weld mark 5. Furthermore, in this embodiment of the present invention, the second weld mark 5 is spaced apart from the edge of the rivet block 4. This not only reserves operating space for the welding process and avoids interference from solder overflow, but also relieves thermal and mechanical stresses during welding, enhancing structural stability and reliability.

[0057] It can be understood that the length of the second weld mark 5 in this embodiment is I' / (γ*W3). The reason why the length of the second weld mark 5 is I' / (γ*W3) is because the second weld mark 5 in this embodiment is rectangular in shape, and the flow coefficient γ represents the current that can pass through the weld mark per unit cross-sectional area. Therefore, when W3 is the width of the second weld mark 5, the length of the first weld mark 3 in this embodiment is equal to I' / (γ*W3).

[0058] It should be noted that the cross-sectional shape of the rivet block 4 in this embodiment can be, but is not limited to, a rectangle. Furthermore, the second weld mark 5 is provided to facilitate the connection of multiple battery cells in series and / or in parallel. Therefore, the rated current I' of the second weld mark 5 in this embodiment is actually the overcurrent requirement of the battery pack formed by connecting multiple battery cells in series and / or in parallel.

[0059] It should be supplemented that, in this embodiment, the rated current I' is in the range of 120A≤I'≤600A.

[0060] According to one embodiment of the present invention, the value range of the overflow coefficient γ of the second weld mark 5 is 5A / mm 2 ≤γ≤8A / mm 2 The distance c between the edge of the rivet block 4 and the corresponding edge of the cover body 1 is in the range of 3mm≤c≤5mm, the distance d between the edge of the second weld mark 5 and the corresponding edge of the rivet block 4 is in the range of 2.7mm≤d≤5mm, and the distance e between the second weld mark 5 and the second through hole is in the range of 3.2mm≤e≤5mm. In the embodiment of the present invention, the flow coefficient γ of the second weld mark 5 is limited to 5A / mm 2 ≤γ≤8A / mm 2 , which can ensure that the second weld mark 5 operates under the appropriate current carrying capacity, meeting the overcurrent requirements of the battery pack while avoiding material waste caused by overheating or too low a current coefficient of the second weld mark 5, thereby optimizing current conduction efficiency; the range of the distance between the rivet block 4 and the edge of the cover body 1 is 3mm≤c≤5mm, the range of the distance between the second weld mark 5 and the edge of the rivet block 4 is 2.7mm≤d≤5mm, and the range of the distance e between the second weld mark 5 and the second through hole is 3.2mm≤d≤5mm. On the one hand, this provides sufficient operating space for the welding process and prevents solder overflow from affecting other components. On the other hand, it can effectively release thermal stress during the welding process, avoid structural damage caused by stress concentration, and enhance the structural stability and assembly adaptability of the battery cover assembly. Specifically, by reasonably limiting c, it is possible to avoid thermal effects on the upper plastic of the battery cover assembly during the subsequent welding of the battery cover assembly to the battery housing. By reasonably setting d and e, it is possible to provide the required space for the welding protective cover to avoid interference with the pole 2.

[0061] It is understood that the value range of γ in this embodiment can be but is not limited to 5A / mm 2 , 5.5A / mm 2 , 6A / mm 2 , 6.5A / mm 2 , 7A / mm 2 , 7.5A / mm 2 , 8A / mm 2 .

[0062] According to one embodiment of the present invention, Figure 5 As shown, the cross-sectional shape of the pole body 201 is in the shape of an athletic track. In the embodiment of the present invention, the cross-sectional shape of the pole 2 is designed to be in the shape of an annular track, which can enable the pole 2 to obtain a larger effective flow area within 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 caused by uneven current density, and ensures that the temperature of the pole 2 is stable during the charging and discharging process.

[0063] According to one embodiment of the present invention, Figure 1 and Figure 5 As shown, the length and width directions of the pole body 201 and the cover body 1 are consistent. The pole body 201 includes a riveted section 2011 and a limiting section 2012. The riveted section 2011 is arranged in the first through hole, and the limiting section 2012 is located outside the first through hole and the second through hole and connected to the pole base 202. Along the width direction of the cover body 1, the width of the riveted section 2011 is W4, the distance between the edge of the riveted section 2011 and the corresponding edge of the riveted block 4 is f, and the width of the limiting section 2012 is W5. The relationship between W2, W4, and f satisfies W4≤W2-2f, and the relationship between W4 and W5 satisfies W5≥W4+0.4mm. The embodiment of the present invention divides the pole body 201 into a riveted section 2011 and a limiting section 2012, and by limiting the relationship between W2, W4, and f (W4≤W2-2f), the width of the riveted section 2011 can be reasonably controlled to ensure that it is adapted for installation with the riveted block 4, avoiding interference due to excessive size or insufficient connection strength due to too small size; and by limiting the relationship between W4 and W5 (W5≥W4+0.4mm), the width of the limiting section 2012 can be made greater than the width of the riveted section 2011, thereby forming a stable limiting structure between the pole base 202 and the riveted block 4, enhancing the connection stability between the pole body 201 and the cover assembly, preventing the pole 2 from being displaced or loosened during use, and thereby improving the overall mechanical strength and reliability of the battery cell cover assembly.

[0064] It should be noted that the value range of f in this embodiment is f≥2mm. In addition, the minimum difference between W5 and W4 is set to 0.4mm in order to avoid cost waste while ensuring riveting strength.

[0065] According to one embodiment of the present invention, Figure 1 and Figure 5 As shown, the end of the limiting section 2012 away from the riveting block 4 is provided with a pole base 202, and the central axis of the pole body 201 is arranged in a collinear manner with the central axis of the pole base 202, and the central axis of the pole body 201 is arranged in a collinear manner with the central axis of the riveting block 4. In order to meet the welding requirements of the battery cell tab 601, the eccentricity of the tab 601 cannot be large or small. Therefore, in the battery cell currently using a bipolar design, the pole base portion of one pole body is usually unable to be welded to the tab 601. Therefore, it is necessary to increase the pole base length of the other pole body to ensure the current 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 pole bodies in the bipolar design battery cell need to be separated by a distance, this requires that the pole body must be an eccentric structure relative to the pole base. Based on this, the embodiment of the present invention sets the central axis of the pole body 201 and the central axis of the pole base 202 in a collinear 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 2 design does not require additional lengthening of the pole base 202, thereby improving material utilization and reducing production costs. While meeting the battery cell's overcurrent capacity and the tab 601 welding requirements, it improves the overall safety, reliability and economy of the battery cell.

[0066] According to one embodiment of the present invention, Figure 3 and Figure 5 As shown, the overcurrent coefficient of the pole body 201 is β, and the value range of β is 8A / mm 2 ≤β≤10A / mm 2 Along the length direction of the cover body 1, the length of the pole body 201 is L3, the relationship between L3, I, β, and W5 satisfies L3 ≥ 4I / (β*π*W5), and the relationship between L3 and g satisfies: g ≤ L3-0.4mm. Wherein, L3 ≤ 18mm.

[0067] In the embodiment of the present invention, the value range of β is set to 8A / mm 2 ≤β≤10A / mm 2, which can ensure that the pole body 201 operates under a reasonable current carrying capacity. In this way, it can meet the transmission requirements of large currents while avoiding overheating problems caused by insufficient overcurrent capacity. Secondly, by defining the relationship between L3, I, β, and W5, the length of the pole body 201 can be matched with the rated current, optimizing the current conduction path, reducing resistance and temperature rise; and through the relationship between L3 and g (g≤L3-0.4mm), the length of the second through hole is guaranteed to adapt to the length of the pole body 201, avoiding installation interference or loose connection problems caused by improper dimensions of the two, and enhancing the assembly stability and structural reliability between the pole 2 and the rivet block 4 and the cover body 1, thereby improving the overall performance and safety of the battery cell and battery pack, reducing the risk of failure, and reducing production costs.

[0068] It is understood that the value range of β in this embodiment can be but is not limited to 8A / mm 2 , 8.5A / mm 2 , 9A / mm 2 , 9.5A / mm 2 , 10A / mm 2 .

[0069] According to an embodiment of the present invention, on the other hand, Figure 6 As shown, a battery cell is also provided, comprising: a pole group 6 and the above-described cell cover assembly. Specifically, a pole tab 601 is provided at one end of the pole group 6; the side of the pole base 202 facing away from the cover body 1 is welded to the pole tab 601 to form a first weld mark 3. The battery cell of this embodiment of the present invention, including the above-described cell cover assembly, has all the beneficial technical effects of the cell cover assembly, which will not be further described here.

[0070] 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.

[0071] In one embodiment, the electrode group 6 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] It should be noted that the tabs 601 in this embodiment include positive and negative tabs. The positive tabs consist of the portion of the positive electrode sheet that does not contain active material, and the negative tabs consist 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 6 or separately at both ends of the electrode assembly 6.

[0077] 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.

[0078] The effects of the present invention are described below with reference to some embodiments and comparative examples.

[0079] Table 1

[0080]

[0081] The test results of Examples 1 to 10 are the same, and all of them show that: the temperature rise at the first weld mark 3 and the temperature rise at the second weld mark 5 are less than 55°C according to overcurrent simulation and thermocouple measurement, meeting the design requirements. At the same time, the weld mark dimensions of the pole base 202 and the rivet block 4 have reached the limit, and there is no design redundancy.

[0082] The experimental results of Comparative Example 1 are based on overcurrent simulation and actual thermocouple measurements. The temperature rise at the first weld mark 3 and the temperature rise at the second weld mark 5 are both less than 55°C, meeting the design requirements. However, the pole base 202 and the rivet block 4 are not fully welded, indicating redundancy in the design and room for cost reduction.

[0083] The test results of Comparative Example 2 are overcurrent simulations. The temperature rise at the first weld mark 3 and the temperature rise at the second weld mark 5 do not meet the design requirements. The dimensions of the pole base 202 and the rivet block 4 are both too small, and the areas of the first weld mark 3 and the second weld mark 5 are insufficient.

[0084] The test results of Comparative Example 3 are overcurrent simulations. The temperature rise at the first weld mark 3 is 56.9°C, which does not meet the design requirements. The dimensions of the pole base 202 and the rivet block 4 are both too small, and the areas of the first weld mark 3 and the second weld mark 5 are insufficient. However, the temperature rise at the second weld mark 5 meets the design requirements.

[0085] The experimental results of comparative example 4 are overcurrent simulation and thermocouple measurement. The temperature rise at the first weld mark 3 and the temperature rise at the second weld mark 5 are both less than 55°C, meeting the design requirements; however, the pole base 202 and the rivet block 4 are not fully welded, the design has redundancy, and there is still room for cost reduction.

[0086] It can be seen that when the size of the pole base 202 satisfies: L1≥I / (σ*a)+2b, a+2*b≤W1≤W-4mm; the size of the pole 2 satisfies: L3≥4I / (β*π*W5), W5≥W4+0.4mm, g≤L3-0.4mm; the size of the rivet block 4 satisfies: W2≤W-2c, L2≥I' / (γ*W3)+4e+g, each structure can meet the overcurrent design requirements, and at the same time, there is no design redundancy in the overcurrent of the pole 2, the welding of the pole base 202 and the rivet block 4, and the cost of the battery cover assembly has reached the lowest; otherwise, either the overcurrent requirements are not met, or there is redundancy in the design, and the manufacturing cost increases.

[0087] 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 cover body is provided with a first through hole, and the width of the cover body is W; The pole comprises a pole body and a pole base provided at one end of the pole body, wherein at least a portion of the pole body is disposed within the first through hole; a first weld mark is provided on a surface of the pole base located outside the first through hole and away from the cover body, wherein the length and width directions of the first weld mark, the pole base, and the cover body are consistent; The width of the first weld mark is a, the rated current of the first weld mark is I, the overcurrent coefficient of the first weld mark is σ, along the width direction or length direction of the cover body, the distance between the edge of the first weld mark and the corresponding edge of the pole base is b, the length of the pole base is L1, and the width of the pole base is W1, wherein the relationship between a, b, and W1 satisfies: a+2*b≤W1≤W-4mm; the relationship between a, b, I, σ, and L1 satisfies: I / (σ*a)+2b≤L1≤I / (σ*a)+2b+3mm.

2. The battery cover assembly according to claim 1, characterized in that: The width a of the first weld mark is in the range of 2 mm ≤ a ≤ 6 mm, the distance b between the edge of the first weld mark and the corresponding edge of the pole base is in the range of 2 mm ≤ b ≤ 5 mm, and the current coefficient σ of the first weld mark is in the range of 5 A / mm 2 ≤σ≤8A / mm 2 .

3. The battery cover assembly according to claim 1, characterized in that: The terminal block further comprises a rivet block provided on a side of the cover body away from the pole base, the rivet block being provided with a second through hole coaxially arranged with the first through hole, and at least a portion of the pole body being passed through the first through hole and the second through hole; a pair of second weld marks are provided on a surface of the rivet block away from the pole base, the pair of second weld marks being respectively located on opposite sides of the second through hole in the length direction of the rivet block, and the length direction and width direction of the second through hole, the second weld mark, the rivet block and the cover body are consistent.

4. The battery cover assembly according to claim 3, characterized in that: The rated current of the second weld mark is I', and the overcurrent coefficient of the second weld mark is γ; along the length direction of the cover body, the length of the second through hole is g, and along the width direction of the cover body, the distance between the edge of the rivet block and the corresponding edge of the cover body is c, and the distance between the edge of the second weld mark and the corresponding edge of the rivet block is d; along the length direction of the cover body, the distance between the second weld mark and the second through hole or the distance between the second weld mark and the corresponding edge of the rivet block is e; the width of the rivet block is W2, the length of the rivet block is L2, and the width of the second weld mark is W3, wherein the relationship between W2, W, and c satisfies: W2≤W-2c, the relationship between W3, W2, and d satisfies: W3≤W2-2d, and the relationship between L2, I', γ, W3, e, and g satisfies: L2≥I' / (γ*W3)+4e+g.

5. The battery cover assembly according to claim 4, characterized in that: The value range of the overflow coefficient γ of the second weld mark is 5A / mm 2 ≤γ≤8A / mm 2 The distance c between the edge of the rivet block and the corresponding edge of the cover body is in the range of 3 mm ≤ c ≤ 5 mm, the distance d between the edge of the second weld mark and the corresponding edge of the rivet block is in the range of 2.7 mm ≤ d ≤ 5 mm, and the distance e between the second weld mark and the second through hole is in the range of 3.2 mm ≤ e ≤ 5 mm.

6. The battery cover assembly according to claim 4, characterized in that: The cross-section of the pole body is in the shape of an athletic track.

7. The battery cover assembly according to claim 6, characterized in that: The length and width directions of the pole body and the cover body are consistent. The pole body includes a riveted section and a limiting section. The riveted section is arranged in the first through hole, and the limiting section is located outside the first through hole and the second through hole and connected to the pole base; along the width direction of the cover body, the width of the riveted section is W4, the distance between the edge of the riveted section and the corresponding edge of the riveted block is f, and the width of the limiting section is W5; the relationship between W2, W4, and f satisfies W4≤W2-2f, and the relationship between W4 and W5 satisfies W5≥W4+0.4mm.

8. The battery cover assembly according to claim 7, characterized in that: The overcurrent coefficient of the pole body is β, and the value range of β is 8A / mm 2 ≤β≤10A / mm 2 Along the length direction of the cover body, the length of the pole body is L3, the relationship between L3, I, β, and W5 satisfies L3≥4I / (β*π*W5), and the relationship between L3 and g satisfies: g≤L3-0.4mm.

9. A battery cell, characterized in that: include: The pole group has a pole ear at one end; In the battery cell cover plate assembly according to any one of claims 1 to 8, the side of the pole base away from the cover body is welded to the pole tab to form the first weld mark.

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

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