Battery cell and battery pack

Abstract

The application relates to the technical field of batteries and discloses a battery cell and a battery pack. The battery cell comprises a shell and a cover plate assembly. A reinforcing part is arranged on the cover plate, the reinforcing part is composed of adjacent convex ribs and concave parts, the convex-concave alternating structure effectively strengthens the structural strength of the cover plate, the ratio between the difference h3 between the thickness of the cover plate body and the concave depth of the concave part and the thickness t of the cover plate body is within the range of 0.5 to 1, the reinforcing part and the convex rib jointly strengthen the structural strength of the cover plate, the cover plate has sufficient structural strength, the cost and weight of the cover plate are reduced, meanwhile, the cover plate is directly overlapped on the open end of the shell through the overlapping part located at the outer peripheral edge of the cover plate, the step structure for supporting the cover plate is avoided from being machined on the side wall of the shell, the wall thickness consistency of all the side walls of the shell is ensured, the material cost and weight of the shell are reduced, the convex rib plays a guiding and positioning role, the shell cover is convenient to assemble, and the relative stability between the cover plate and the shell is ensured.

Description

Technical Field

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

[0002] Batteries are widely used in electric vehicles, energy storage, and other fields, making their performance and safety paramount. A battery cell typically includes a casing, a cover assembly covering the opening of the casing, and electrode arrays located inside the casing. When a battery cell is exposed to vibration and shock, the cover area is subjected to significant shear force. If the cover's strength is insufficient, it can lead to failure in weak areas such as the welded joints between the casing and the cover. Current cover technologies typically use flat plates with relatively poor structural strength. Increasing the cover's thickness to improve structural strength would increase the cost of cover materials and the weight of the battery cell.

[0003] In addition, in order to improve the assembly and welding yield of the cover plate and the housing, a stepped structure that matches the cover plate is usually set on the relatively narrow side wall of the housing. However, the wall thickness of the side wall with the stepped structure is greater than that of the side wall without the stepped structure, which makes the wall thickness of all the side walls of the housing not completely uniform, making the processing complicated, and also increasing the material cost of the housing and the weight of the battery cell. Summary of the Invention

[0004] In view of this, the present invention provides a battery cell and battery pack to solve the problems of poor strength of the cover plate structure, high material cost and heavy weight of the battery cell.

[0005] In a first aspect, the present invention provides a battery cell, comprising: a housing having an open end, the end face of the open end being a first end face; a cover plate assembly disposed at the open end of the housing, the cover plate assembly including a cover plate, the cover plate including a cover plate body, a reinforcing portion and an overlapping portion, the cover plate body having a first center line extending along its thickness direction, the cover plate body having a first outer peripheral surface facing away from the first center line in a direction perpendicular to the first center line, the reinforcing portion being connected around the first outer peripheral surface, the reinforcing portion having a first outer peripheral surface facing away from the first center line in a direction perpendicular to the first center line. The second outer peripheral surface of the line, the overlapping portion is connected around the second outer peripheral surface, the reinforcing portion is constructed with a rib and a recess along the thickness direction towards the inner cavity of the shell, the rib is connected to the overlapping portion, the recess is connected between the rib and the cover plate body, the rib is located in the inner cavity of the shell, and the overlapping portion overlaps on the first end face; along the thickness direction, the thickness of the cover plate body is t, the difference between the thickness of the cover plate body and the recess depth of the recess is h3, wherein h3 and t satisfy the relationship: 0.5≤h3 / t≤0.9.

[0006] Beneficial Effects: By incorporating reinforcing sections on the cover plate, consisting of raised ribs and recessed sections, the alternating convex and concave structure effectively enhances the structural strength of the cover plate. Compared to the traditional method of increasing strength by increasing the thickness of the cover plate, this effectively reduces the material usage, thereby saving costs and reducing the weight of the cover plate. Furthermore, by limiting the ratio h3 / t between the thickness of the cover plate body and the depth of the recessed section (h3) and the thickness t of the cover plate body to a value between 0.5 and 1, it ensures that the recessed section has an effective depth while avoiding excessive depth that could deplete the structural strength of the cover plate. This effectively achieves the combined effect of the recessed section and the raised ribs in strengthening the structural strength of the cover plate, thus ensuring sufficient structural strength. The structural strength of the cover plate is improved, enhancing the safety of the cover plate assembly and the battery cell. Simultaneously, the cover plate directly overlaps with the first end face of the opening of the housing via an overlapping portion located on its outer periphery. The protruding ribs adjacent to the overlapping portion play a guiding and positioning role during the assembly of the cover plate and the housing. Furthermore, after the cover plate is assembled, the ribs mutually limit each other with the inner wall of the housing, facilitating cover plate assembly and ensuring relative stability between the cover plate and the housing. This also facilitates subsequent cover plate welding and avoids the need to machine stepped structures on the side walls of the housing to support the cover plate, ensuring consistent wall thickness across all side walls of the housing. This facilitates housing processing and shaping, and reduces the material cost and weight of the housing. Therefore, while improving the structural strength of the cover plate, the material cost and weight of the battery cell are reduced, contributing to lightweight design.

[0007] In one optional implementation, the value of t is in the range of: 0.5 mm ≤ t ≤ 10 mm;

[0008] And / or, the range of h3 is: 0.8 mm ≤ h3 ≤ 9 mm.

[0009] Beneficial effects: By limiting t to a value between 0.5 mm and 10 mm, the cover plate body has a reasonable thickness, which can ensure that the cover plate body has sufficient structural strength, thereby ensuring the reliability of the cover plate and the safety of the battery cell, while avoiding material waste, which helps to reduce the weight of the cover plate and achieve lightweighting of the battery cell.

[0010] And / or, by limiting h3 to a value between 0.8 mm and 9 mm, the structural strength of the cover plate can be guaranteed, thereby ensuring the structural reliability of the cover plate and improving the safety performance of the battery cell.

[0011] In one alternative embodiment, along a direction perpendicular to the first centerline, the overlapping portion has a third outer peripheral surface facing away from the first centerline, and the housing has an outer wall surface facing away from the inner cavity of the housing. The vertical distance between the third outer peripheral surface and the outer wall surface is e, where 0 mm ≤ e ≤ 0.5 mm.

[0012] And / or, along a direction perpendicular to the first center line, the rib is clearance-fitted with the housing, and the distance between the outer wall of the rib and the inner wall of the housing is g1, wherein the value of g1 is in the range of 0.03 mm ≤ g1 ≤ 0.3 mm.

[0013] Beneficial effects: By limiting the distance e between the third outer peripheral surface and the outer wall surface in the direction perpendicular to the first center line to be within the range of 0 mm to 0.5 mm, the step difference between the shell and the cover is within a reasonable range, which can avoid welding defects such as incomplete welds or blasting points during the welding of the shell and the cover, thereby ensuring the welding strength, which is conducive to improving the connection strength between the cover and the shell after welding, and ensuring the pass rate of the battery cell.

[0014] And / or, by limiting g1 to a value between 0.03 mm and 0.3 mm, a reasonable gap size is achieved between the rib and the inner wall of the shell. This ensures that the rib can smoothly enter the shell during the assembly of the cover assembly and the shell, guaranteeing the smooth installation of the cover assembly. It also ensures that the rib can play a good guiding role during the installation of the cover assembly and provide a certain positioning and support role after the cover assembly is installed, preventing the cover assembly and the shell from being too loose after assembly. Furthermore, it is easier to control the step difference e between the shell and the cover within a reasonable range, ensuring the welding yield of the shell and the cover.

[0015] In one optional embodiment, the dimension of the rib along the thickness direction is h2, wherein the value of h2 is in the range of 0.4 mm ≤ h2 ≤ 10 mm.

[0016] Beneficial effects: By limiting h2 to a value between 0.4 mm and 10 mm, the rib has a reasonable size along the thickness direction. This ensures a stable fit between the cover assembly and the shell during assembly, preventing the cover assembly from falling off the shell, facilitating production line assembly and welding, improving assembly efficiency, ensuring the rib can be formed smoothly, avoiding material waste, reducing weight, and saving costs.

[0017] In one alternative embodiment, the recess is an annular groove surrounding the cover plate body, and the rib is a raised ring connecting the annular groove and the overlapping portion.

[0018] Beneficial effects: By setting the recessed part as an annular groove and the rib as a convex ring, it is easy to process and shape the recessed part and the rib. Through the alternating concave and convex structure, the structural strength of the entire edge of the cover plate is improved, thereby improving the overall structural strength of the cover plate. This is conducive to reducing the thickness of the cover plate. While ensuring structural strength, it avoids excessive material usage and weight of the cover plate, which helps to reduce material costs and reduce the weight of the battery cell.

[0019] In one optional embodiment, on a cross section parallel to the thickness direction and passing through the first center line, the cross-sectional area of ​​the recess is S1, and the cross-sectional area of ​​the rib is S2, wherein S1 and S2 satisfy the relationship: 0.8≤S1 / S2≤1.3.

[0020] Beneficial effects: By limiting the values ​​of S1 / S2 to the range of 0.8 to 1.3, the recessed parts and ribs can be formed smoothly, thereby effectively improving the structural strength and reliability of the cover plate.

[0021] In one optional embodiment, the outer peripheral wall of the rib is a first side surface, the end face of the rib facing away from the cover plate body along the thickness direction is a second end face, and the included angle between the first side surface and the second end face is an obtuse angle.

[0022] Beneficial effects: By setting the angle between the outer peripheral wall of the rib and the end face of the rib away from the cover plate to be obtuse, the cross section of the rib is trapezoidal, which facilitates demolding after stamping and helps to improve product yield and processing efficiency.

[0023] In one optional embodiment, the included angle between the first side surface and the second end surface is B, wherein the value of B is in the range of 92°≤B≤105°.

[0024] And / or, the second end face is annular, and the width of the annulus formed by the second end face is w1, wherein the value of w1 is in the range of 0.3 mm ≤ w1 ≤ 10 mm.

[0025] Beneficial effects: By limiting B to a value within the range of 92° to 105°, it is possible to avoid scratching the wall surface of the ribs during the stamping and demolding of the cover plate, thereby ensuring the appearance quality, avoiding stress concentration at the scratches that could lead to cracking or deformation, and preventing metal debris from falling into the battery cell and affecting its performance, thus ensuring the reliability of the cover plate assembly and the battery cell. It is also possible to avoid the cover plate assembly being too loose, thereby ensuring that the cover plate will not easily fall off the casing during production, ensuring smooth battery cell assembly, and improving assembly efficiency and operational safety.

[0026] And / or, by limiting w1 to a value within the range of 0.3 mm to 10 mm, the structural strength of the rib can be guaranteed, and the operator can be prevented from being scratched by the rib being too sharp, thus improving the production yield and production safety. It can also ensure that the rib can be formed smoothly, avoid material waste, save costs, reduce weight, and help improve the energy density of the battery cell.

[0027] In one optional embodiment, the dimension of the overlap portion along the thickness direction is h1, wherein the value of h1 ranges from 0.5 mm to h1 to 10 mm.

[0028] And / or, the wall thickness of the shell is w2, wherein the value of w2 is in the range of 0.4 mm ≤ w2 ≤ 1.0 mm.

[0029] Beneficial effects: By limiting h1 to a value between 0.5 mm and 10 mm, the overlap portion has a reasonable thickness, which can ensure that the overlap portion has sufficient structural strength and provide sufficient space for the weld pool during the welding of the shell and cover along the thickness direction, thereby ensuring the welding strength, the stability and reliability of the connection between the cover and the shell after welding, and also avoids material waste, which helps to reduce the weight of the cover and facilitates the lightweighting of the battery cell.

[0030] And / or, by limiting w2 to a value between 0.4 mm and 1.0 mm, it can be ensured that the sidewall of the casing will not be welded through during the casing welding process, thereby ensuring the welding quality and the reliability of the casing connection. It can also avoid wasting materials, save costs, reduce weight, and help improve the energy density of the battery cell.

[0031] Secondly, the present invention also provides a battery pack, comprising: a housing; and the aforementioned battery cell, wherein the battery cell is disposed within the housing. Since the battery pack includes the battery cell and has the same effects as the battery cell, further details are omitted here. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a front view of a battery cell according to an embodiment of the present invention;

[0034] Figure 2 for Figure 1 A cross-sectional view along the AA direction;

[0035] Figure 3 for Figure 2 A magnified view of part B in the diagram;

[0036] Figure 4 for Figure 3 A schematic diagram of the structure after adding solder marks;

[0037] Figure 5 for Figure 3 Structural diagram of the middle cover plate section;

[0038] Figure 6 This is a schematic diagram of the structure of a cover plate assembly according to an embodiment of the present invention;

[0039] Figure 7 for Figure 6 A magnified view of part C in the diagram.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Shell; 101. First end face; 102. Outer wall surface; 2. Cover plate; 201. Cover plate body; 202. Reinforcing part; 2021. Raised rib; 2022. Recessed part; 2023. First side; 2024. Second end face; 203. Overlapping part; 2031. Third outer peripheral surface; 3. Pole post; 4. Explosion-proof valve; 5. Injection hole; 6. Pole assembly. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] The following is combined Figures 1 to 7 The following describes embodiments of the present invention.

[0044] According to an embodiment of the present invention, a battery cell is provided, comprising: a housing 1 and a cover plate assembly. The housing 1 has an open end, the end face of which is a first end face 101; the cover plate assembly is disposed at the open end of the housing 1, the cover plate assembly comprising a cover plate 2, the cover plate 2 comprising a cover plate body 201, a reinforcing portion 202, and an overlapping portion 203, the cover plate body 201 having a first centerline extending along its thickness direction, the cover plate body 201 having a first outer peripheral surface facing away from the first centerline in a direction perpendicular to the first centerline, the reinforcing portion 202 being circumferentially connected to the first outer peripheral surface, the reinforcing portion 202 having a second outer peripheral surface facing away from the first centerline in a direction perpendicular to the first centerline, and the overlapping portion 203 being circumferentially connected to the first outer peripheral surface. On the outer circumferential surface, the reinforcing part 202 has a raised rib 2021 and a recessed part 2022 on the side of the shell 1 facing the inner cavity along the thickness direction. The raised rib 2021 is connected to the overlapping part 203, and the recessed part 2022 is connected between the raised rib 2021 and the cover plate body 201. The raised rib 2021 is located in the inner cavity of the shell 1, and the overlapping part 203 overlaps on the first end face 101. Along the thickness direction, the thickness of the cover plate body 201 is t, and the difference between the thickness of the cover plate body 201 and the recessed depth of the recessed part 2022 is h3. The relationship between h3 and t is: 0.5≤h3 / t≤0.9.

[0045] It should be noted that the thickness direction mentioned refers to the thickness direction of cover plate 2, specifically... Figure 3 The "thickness direction" indicated by the middle arrow refers to both the thickness and the depth of the depression. Figure 3 The dimensions in the "thickness direction" indicated by the middle arrow; the division of the cover plate body 201, the reinforcing part 202, and the overlapping part 203 is as follows: Figure 3 As shown by the dashed lines in the diagram, it should be noted that the dashed lines are for illustrative purposes only and do not actually exist. The cover body 201 is located in the central area of ​​the entire cover 2, and the first center line of the cover body 201 is also the center line of the cover 2. The center lines of the reinforcing part 202 and the overlapping part 203 are both collinear with the first center line. The reinforcing part 202 is connected to the side of the cover body 201 that is away from the first center line, that is, the reinforcing part 202 is connected to the outer periphery of the cover body 201. The overlapping part 203 is connected to the side of the reinforcing part 202 that is away from the first center line, that is, the overlapping part 203 is connected to the outer periphery of the reinforcing part 202.

[0046] It should also be noted that the cover plate 2 in this embodiment is stamped from a plate-shaped raw material to form ribs 2021 and recesses 2022. The areas on the plate with ribs 2021 and recesses 2022 form reinforcing parts 202, increasing the structural strength of the cover plate 2. The ribs 2021 protrude from the surface of the cover plate body 201 facing the housing along the thickness direction, and the recesses 2022 are recessed relative to the surface of the cover plate body 201 facing the housing in a direction away from the housing 1. The opening side of the recesses 2022 faces the inner cavity of the housing 1. Along the thickness direction, the difference h3 between the thickness of the cover plate body 201 and the recess depth of the recesses 2022 refers to the area of ​​the reinforcing part 202 after removing the recesses 2022. The thickness of the remaining solid portion after the material of 022 is the same as the thickness of the cover plate body 201 when the original thickness of the unprocessed recessed portion 2022 and the rib 2021 of the reinforcing part 202 is t. If h3 / t is less than 0.5, the thickness of the remaining solid portion after the recessed portion 2022 is too small relative to the thickness of the cover plate body 201, that is, the recessed depth of the recessed portion 2022 is too large, the strength of the cover plate 2 is significantly reduced, and the cover plate 2 is prone to deformation during assembly or use, affecting the safety of the cover plate assembly. If h3 / t is greater than 0.9, the recessed depth of the recessed portion 2022 is too small, the structural reinforcement effect of the cover plate 2 is weak, and it cannot effectively strengthen the structural strength of the cover plate 2.

[0047] The battery using this embodiment, by providing a reinforcing part 202 on the cover plate 2, and the reinforcing part 202 being composed of a convex rib 2021 and a recessed part 2022, the alternating convex and concave structure effectively strengthens the structural strength of the cover plate 2. Compared with the traditional method of increasing strength by increasing the thickness of the cover plate 2, it can effectively reduce the material used for the cover plate, thereby saving the cost and reducing the weight of the cover plate 2. Furthermore, by limiting the ratio h3 / t between the difference h3 between the thickness of the cover plate body 201 and the recessed depth h3 of the recessed part 2022 and the thickness t of the cover plate body 201 to a value in the range of 0.5 to 1, it can be ensured that the recessed part 2022 has an effective recessed depth, while avoiding excessive concavity of the recessed part 2022 which would excessively reduce the structural strength of the cover plate 2. Thus, the recessed part 2022 and the convex rib 2021 jointly strengthen the structural strength of the cover plate 2, thereby... This effectively ensures that the cover plate 2 has sufficient structural strength, improving the safety of the cover plate assembly and the battery cell. At the same time, the cover plate 2 directly overlaps with the first end face 101 of the opening end of the housing 1 through the overlapping part 203 located on its outer peripheral edge. The protruding rib 2021 arranged adjacent to the overlapping part 203 plays a certain guiding and positioning role during the assembly of the cover plate 2 and the housing 1. After the cover is assembled, the protruding rib 2021 mutually limits the inner wall of the housing 1, which facilitates the assembly of the cover and ensures the relative stability between the cover plate 2 and the housing 1. This facilitates the subsequent welding of the cover and avoids the need to process the stepped structure for supporting the cover plate 2 on the side wall of the housing 1, ensuring the uniformity of the wall thickness of all side walls of the housing 1, facilitating the processing and forming of the housing 1, and reducing the material cost and weight of the housing 1. Thus, while improving the structural strength of the cover plate, the material cost and weight of the battery cell are reduced, which is conducive to achieving lightweighting.

[0048] It should be noted that the shell and cover assembly mentioned refers to the assembly of cover plate 2 and shell 1; the shell and cover welding refers to the welding of cover plate 2 and shell 1.

[0049] Optionally, h3 / t can take any value from 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, or a value between any two values.

[0050] It should be noted that, along the thickness direction, the surface of the reinforcing part 202 on the side away from the housing 1 is flush with the surface of the cover plate body 201 on the side away from the housing 1. That is, the surface of the cover plate 2 on the side away from the housing 1 along the thickness direction is flat. The reinforcing part 202, the cover plate body 201 and the overlapping part 203 are integrally formed, preferably by stamping.

[0051] Preferably, the battery cell is a square battery cell, and the outer contour of the cover plate 2 is quadrilateral.

[0052] In one embodiment, the value of t ranges from 0.5 mm to 10 mm. It should be noted that t represents the thickness of the cover plate body 201, which is the main area on the cover plate 2. If t is less than 0.5 mm, the thickness of the cover plate body 201 is too small, resulting in insufficient structural strength of the cover plate 2, making it prone to deformation during processing or use, and leading to poor reliability. If t is greater than 10 mm, the thickness of the cover plate body 201 is too large, wasting material and increasing weight, which is detrimental to improving the energy density of the battery cell. Therefore, by limiting t to a value between 0.5 mm and 10 mm, the cover plate body 201 has a reasonable thickness, ensuring sufficient structural strength to guarantee the reliability of the cover plate 2 and the safety of the battery cell, while also avoiding material waste and reducing the weight of the cover plate 2, thus achieving lightweighting of the battery cell.

[0053] Optionally, t can be any value among 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or a value between any two of these values.

[0054] In one embodiment, the value of h3 ranges from 0.8 mm to 9 mm. It should be noted that if h3 is less than 0.8 mm, the residual thickness corresponding to the recess 2022 on the cover plate 2 is too small, resulting in insufficient structural strength. This makes the portion prone to deformation or breakage during assembly or use, affecting the safety of the battery cell. If h3 is greater than 9 mm, the recess depth of the recess 2022 is too small, failing to adequately strengthen the structural strength of the cover plate 2. Therefore, by limiting h3 to a value between 0.8 mm and 9 mm, the structural strength of the cover plate 2 can be guaranteed, thereby ensuring its structural reliability and improving the safety performance of the battery cell.

[0055] Optionally, h3 can be any value among 0.8 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, and 9 mm, or a value between any two of these values.

[0056] In one embodiment, further combination Figure 3As shown, along a direction perpendicular to the first centerline, the overlapping portion 203 has a third outer peripheral surface 2031 facing away from the first centerline, and the housing 1 has an outer wall surface 102 facing away from the inner cavity of the housing 1. The vertical distance between the third outer peripheral surface 2031 and the outer wall surface 102 is e, where 0 mm ≤ e ≤ 0.5 mm. It should be noted that the first end face 101 is annular, and the projection of the outer wall surface 102 along the thickness direction onto the plane where the first end face 101 is located is the outer ring of the first end face 101; the third outer peripheral surface 2031 on the overlapping portion 203 is the outer peripheral surface of the cover plate 2; the surface of the overlapping portion 203 near the side of the housing 1 along the thickness direction is the overlapping surface, and the first end face 101 of the housing 1 abuts against the overlapping surface. The distance between the annular outer ring of the first end face 101 and the outer peripheral edge of the overlapping portion 203 is e, where e is the difference in the mating step between the cover plate 2 and the housing 1; the edge of the cover plate 2 can extend beyond the outer wall of the housing 1 (e.g., Figure 3 As shown in the figure), or the outer edge of the cover plate 2 is collinear with the outer side wall of the housing 1 (not shown in the figure), or the outer edge of the cover plate 2 is located within the range of the first end face 101 (not shown in the figure), that is, the edge of the cover plate 2 is located between the outer side wall and the inner side wall of the housing 1. It is necessary to ensure that the step difference between the housing cover and the cover is within 0±0.5 mm. If the step difference is too large, it will cause the housing cover to have poor welding and explosion points during welding, and the welding strength will be insufficient.

[0057] Therefore, by limiting the distance e between the third outer peripheral surface 2031 and the outer wall surface 102 in the direction perpendicular to the first center line to be within the range of 0 mm to 0.5 mm, the step difference of the shell cover fit is within a reasonable range, which can avoid welding defects such as incomplete welds or bursts during the welding of the shell cover, thereby ensuring the welding strength and improving the connection strength between the cover plate 2 and the shell 1 after welding, thus ensuring the pass rate of the battery cell.

[0058] Optionally, e can be any value among 0 mm, 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, and 0.5 mm, or a value between any two values.

[0059] In one embodiment, along a direction perpendicular to the first center line, the outer wall of the rib 2021 is clearance-fitted with the housing 1, and the distance between the rib 2021 and the inner wall of the housing 1 is g1, wherein the value of g1 is in the range of 0.03 mm ≤ g1 ≤ 0.3 mm. It should be noted that the inner wall of housing 1 refers to the side wall of housing 1 facing the inner cavity of housing; the outer wall of rib 2021 refers to the side wall of rib 2021 facing the side wall of housing it mates with; rib 2021 extends into the inner cavity of housing 1. By setting the rib 2021 and housing 1 to have a clearance fit, a small gap is formed between the rib 2021 and the inner wall of housing 1. The rib 2021 is positioned close to the inner wall of housing to provide guidance for the cover plate assembly during assembly with housing. If g1 is less than 0.03 mm, the gap between the rib 2021 and the inner wall of housing 1 is too small, the rib 2021 is too close to the inner wall of housing 1, the cover plate assembly is too tight during assembly with housing 1, and the cover plate assembly is difficult to insert into housing. If g1 is greater than 0.3 mm... If the gap between the rib 2021 and the inner wall of the housing 1 is too large, the rib 2021 is too far from the inner wall of the housing 1, the cover plate assembly is too loosely fitted to the housing 1, the rib 2021 cannot play a good guiding role in the process of the cover plate assembly entering the housing, and it will lead to poor control of the step difference e between the housing and the cover, which is easy to exceed the tolerance, and thus cause poor welding of the housing and the cover.

[0060] Therefore, by limiting g1 to a value between 0.03 mm and 0.3 mm, a reasonable gap size is achieved between the rib 2021 and the inner wall of the housing 1. This ensures that the rib 2021 can smoothly enter the housing 1 during the assembly of the cover assembly and the housing 1, guaranteeing the smooth installation of the cover assembly. It also ensures that the rib 2021 can play a good guiding role during the installation of the cover assembly and provide a certain positioning and support role after the cover assembly is installed, preventing the cover assembly from being too loose after assembly with the housing 1. Furthermore, it is easier to control the step difference e between the cover and the housing within a reasonable range, ensuring the welding yield of the cover.

[0061] Optionally, g1 can be any value among 0.03 mm, 0.05 mm, 0.08 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, and 0.3 mm, or a value between any two of these values.

[0062] In one embodiment, further combination Figure 6As shown, the recessed portion 2022 is an annular groove surrounding the cover plate body 201, and the rib 2021 is a raised ring connecting the annular groove and the overlapping portion 203. The annular groove and the raised ring are concentrically arranged, and the raised ring is connected to the outer periphery of the annular groove. By setting the recessed portion 2022 as an annular groove and the raised ring 2021 as a raised ring, it is convenient to process and form the recessed portion 2022 and the raised ring 2021. Through the alternating concave and convex structure, the structural strength of the entire edge of the cover plate 2 is improved, thereby improving the overall structural strength of the cover plate 2. This is beneficial for reducing the thickness of the cover plate 2. While ensuring structural strength, it avoids excessive material usage and weight of the cover plate 2, which helps to reduce material costs and reduce the weight of the battery cell.

[0063] In one embodiment, on a cross-section parallel to the thickness direction and passing through the first centerline, the cross-sectional area of ​​the recess 2022 is S1, and the cross-sectional area of ​​the rib 2021 is S2, wherein S1 and S2 satisfy the relationship: 0.8 ≤ S1 / S2 ≤ 1.3. It should be noted that the recess 2022 is generally an annular groove, and the rib 2021 is a convex ring. There are several cross-sections parallel to the thickness direction and passing through the first centerline. S1 and S2 are the areas of a single side cross-section of the annular groove and the rib 2021, respectively, on any one of these cross-sections. S1 and S2 are respectively as shown in the figure below. Figure 5 As indicated by the shaded area pointed to by the middle arrow, the raised rib 2021 and the recessed portion 2022 on the cover plate 2 are formed by stamping. The raw material originally located in the recessed portion 2022 moves outward, combined with a small amount of material moving outward at the overlapping portion 203 and other positions, forming the raised rib 2021. If S1 / S2 is greater than 1.3, the cross-sectional area of ​​the annular groove is too large relative to the cross-sectional area of ​​the raised ring, and the cross-sectional size of the raised rib 2021 is too small. The amount of material that needs to be removed from the recessed portion 2022 is much greater than the amount of material required for the forming of the raised rib 2021, which can easily cause stress concentration and cracking on the raised rib 2021. The recessed portion 2022 and the raised rib 2021 cannot be formed smoothly. If S1 / S2 is less than 0.8, the cross-sectional area of ​​the annular groove is too small relative to the cross-sectional area of ​​the raised ring, and there is not enough material to provide for the raised rib 2021 during the forming process, so it cannot be formed. That is, if S1 / S2 is too large or too small, the raised rib 2021 will not be formed.

[0064] Therefore, by limiting the values ​​of S1 / S2 to the range of 0.8 to 1.3, the recessed portion 2022 and the raised rib 2021 can be formed smoothly, thereby effectively improving the structural strength and reliability of the cover plate 2.

[0065] Optionally, the value of S1 / S2 can be any one of 0.8, 0.85, 0.9, 0.95, 1.0, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3 or a value between any two values.

[0066] In one embodiment, the cross-section of the recess 2022 and the cross-section of the rib 2021 are both trapezoidal, which facilitates processing and demolding.

[0067] In other embodiments, the cross-section of the recess 2022 and the cross-section of the rib 2021 may also be semi-circular, elliptical or other polygonal.

[0068] In one embodiment, the value of S2 ranges from approximately 0.144 mm. 2 ~120 mm 2 This ensures that the rib 2021 has a reasonable cross-sectional area, preventing the rib 2021 from being too small or too large to form properly, and ensuring that the rib 2021 can effectively strengthen the structural strength of the cover plate 2.

[0069] In one embodiment, the value of S1 ranges from approximately 0.115 mm. 2 ~152 mm 2 This ensures that the recessed portion 2022 has a reasonable cross-sectional area, which can prevent the recessed portion 2022 from being too small to effectively strengthen the cover plate 2, and also prevent the recessed portion 2022 from being too large to make the residual thickness on the cover plate 2 too small, thereby further ensuring the structural strength of the cover plate 2.

[0070] In one embodiment, further combination Figure 3 As shown, the outer peripheral wall of the rib 2021 is the first side surface 2023, and the end face of the rib 2021 facing away from the cover plate body 201 along the thickness direction is the second end face 2024. The included angle between the first side surface 2023 and the second end face 2024 is an obtuse angle. It should be noted that the rib 2021 is in the shape of a convex ring, and the outer peripheral wall of the rib 2021 refers to the circumferential surface of the rib 2021 facing away from the center of the convex ring, that is, the surface of the rib 2021 facing the side wall of the shell 1. The cover plate 2 is formed by stamping, and the rib 2021 needs to have a certain demolding angle to facilitate demolding by the stamping die. By setting the included angle between the outer peripheral wall of the rib 2021 and the end face of the rib 2021 facing away from the cover plate 2 to an obtuse angle, the cross section of the rib 2021 is trapezoidal, which facilitates demolding after stamping and helps to improve product yield and processing efficiency.

[0071] In one embodiment, the included angle between the first side surface 2023 and the second end surface 2024 is B, where the value of B ranges from 92° to 105°. It should be noted that B is the demolding angle during drafting. If B is less than 92°, the demolding angle is too small, and the wall surface of the cover plate 2 is easily scratched during stamping and demolding, affecting the appearance quality. The scratched areas become structural weak points, prone to stress concentration under load, making cracking or deformation more likely. Metal fragments generated after scratching may fall into the battery cell and contaminate the electrolyte or electrode materials, leading to a decrease in battery cell performance. If B is greater than 105°, the demolding angle is too large, the distance between the second end surface 2024 of the rib 2021 and the side wall of the casing is too large, the casing assembly is too loose, and the cover plate 2 is prone to falling off during production, increasing the difficulty and danger of battery cell assembly.

[0072] Therefore, by limiting B to a value within the range of 92° to 105°, it is possible to avoid scratching the wall surface of the rib 2021 during the stamping and demolding of the cover plate 2, thereby ensuring the appearance quality, avoiding stress concentration at the scratches that could lead to cracking or deformation, and preventing metal debris from falling into the battery cell and affecting its performance, thus ensuring the reliability of the cover plate assembly and the battery cell. It is also possible to avoid the cover assembly being too loose, thereby ensuring that the cover plate 2 will not easily fall off the housing 1 during production, ensuring the smooth assembly of the battery cell, and improving the assembly effect and operational safety.

[0073] Optionally, the value of B can be any value or a value between any two of the following: 92°, 93°, 94°, 95°, 96°, 97°, 98°, 99°, 100°, 101°, 102°, 103°, 104°, and 105°.

[0074] In one embodiment, the second end face 2024 is annular, and the width of the annulus is w1, where w1 ranges from 0.3 mm to 10 mm. It should be noted that since the rib 2021 is annular and the second end face 2024 is the end face of the rib 2021 facing away from the cover plate 2, the second end face 2024 is annular. If w1 is less than 0.3 mm, the width of the second end face 2024 is too small, the rib 2021 is too sharp, the structural strength is poor, and it is easy to scratch operators during production. If w1 is greater than 10 mm, the width of the second end face 2024 is too large, the rib 2021 is difficult to stamp, and it wastes material and is too heavy. Therefore, by limiting w1 to a value within the range of 0.3 mm to 10 mm, the structural strength of the rib 2021 can be guaranteed, and the operator can be prevented from being scratched by the rib 2021 being too sharp, thus improving the production yield and production safety. At the same time, the rib 2021 can be formed smoothly, avoiding material waste, saving costs, reducing weight, and helping to improve the energy density of the battery cell.

[0075] Optionally, w1 can be any value among 0.3 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or a value between any two of these values.

[0076] In one embodiment, the dimension of the rib 2021 along the thickness direction is h2, where the value of h2 ranges from 0.4 mm to h2 to 10 mm. Here, the thickness direction refers to... Figure 3 The arrow points to the "thickness direction". It should be noted that during the assembly of the shell cover, the rib 2021 extends into the interior of the shell 1 and is close to the inner side of the side wall of the shell 1, playing a certain positioning and fixing role. h2 is the dimension of the rib 2021 along the thickness direction, that is, the dimension extending into the interior of the shell 1. If h2 is less than 0.4 mm, the dimension of the rib 2021 along the thickness direction is too small, and the dimension extending into the interior of the shell 1 and fitting with the side wall of the shell is insufficient. During the assembly of the shell cover, the cover plate assembly is easy to pop out from the shell 1, which is not convenient for production line assembly and shell cover welding. If h2 is greater than 10 mm, the dimension of the rib 2021 along the thickness direction is too large, the rib 2021 is difficult to stamp and form, and it wastes materials and is too heavy.

[0077] Therefore, by limiting h2 to a value between 0.4 mm and 10 mm, the rib 2021 has a reasonable size along the thickness direction. This ensures a stable fit between the cover assembly and the housing 1 during the assembly of the cover, preventing the cover assembly from falling off the housing 1, facilitating assembly and welding on the production line, and improving assembly efficiency. It also ensures that the rib 2021 can be formed smoothly, avoids material waste, reduces weight, and saves costs.

[0078] Optionally, h2 can be any value among 0.4 mm, 0.8 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or a value between any two of these values.

[0079] In one embodiment, the dimension of the overlapping portion 203 along the thickness direction is h1, where the value of h1 ranges from 0.5 mm to 10 mm. It should be noted that after the overlapping portion 203 overlaps the first end face 101 of the housing 1, it needs to be welded to the housing 1. The welding position is as follows... Figure 4As indicated by the arrow "P", laser welding is the preferred welding method. To ensure welding strength, a certain weld pool width is required. If h1 is less than 0.5 mm, the overlap portion 203 will not provide sufficient space for the weld pool along its thickness direction, resulting in a small weld width, insufficient welding strength, and poor connection stability between the cover plate 2 and the shell 1. Furthermore, an excessively small h1 will also lead to insufficient structural strength of the overlap portion 203, similarly affecting the reliability of the connection between the cover plate 2 and the shell 1. If h1 is greater than 10 mm, the thickness of the overlap portion 203 will be too large, wasting material and increasing weight, which is detrimental to improving the energy density of the battery cell. Here, the weld pool width refers to the width of the weld along the weld line. Figure 4 The dimension in the "thickness direction" indicated by the middle arrow.

[0080] Therefore, by limiting h1 to a value between 0.5 mm and 10 mm, the overlap portion 203 has a reasonable thickness. This ensures that the overlap portion 203 has sufficient structural strength and provides sufficient space for the welding pool during the welding of the shell cover along the thickness direction, thereby ensuring welding strength and the stability and reliability of the connection between the cover plate 2 and the shell 1 after welding. It also avoids wasting materials, helps reduce the weight of the cover plate 2, and facilitates the lightweighting of the battery cell.

[0081] Optionally, h1 can be any value among 0.5 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, and 10 mm, or a value between any two of these values.

[0082] In one embodiment, the wall thickness of the housing 1 is w2, where the value of w2 ranges from 0.4 mm to w2 to 1.0 mm. Further combining... Figures 3 to 4 As shown, to ensure the welding strength of the casing, a certain weld pool depth is required. The weld pool depth refers to the dimension of the weld pool along the wall thickness direction of casing 1. If w2 is less than 0.4 mm, the wall thickness of casing 1 is too thin, making it prone to weld penetration and leading to welding deformation and failure. If w2 is greater than 1.0 mm, the wall thickness of casing 1 is too thick, wasting material and increasing weight. Therefore, by limiting w2 to a value between 0.4 mm and 1.0 mm, it is possible to ensure that the sidewall of casing 1 will not be welded through during the casing welding process, thus guaranteeing welding quality and the reliability of the casing connection. This also avoids material waste, saves costs, reduces weight, and is beneficial for improving the energy density of the battery cell.

[0083] Optionally, w2 can be any value among 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm, or a value between any two of these values.

[0084] It should be noted that at least one end of the housing 1 is configured as an open end. Optionally, one end of the housing 1 is configured as an open end, and the housing 1 includes a side wall and a bottom wall, with the bottom wall disposed opposite to the open end, and the side wall circumferentially surrounding the bottom wall; it can be understood that, as an alternative embodiment, the housing 1 may also be configured with both ends as open ends, each open end being provided with a set of cover plate assemblies, and the housing 1 being surrounded by the side walls. The wall thickness of the side wall is w2 as described above.

[0085] In one embodiment, the battery further includes an electrode assembly 6, which is disposed in the inner cavity of the housing 1. The electrode assembly 6 includes a positive electrode, a negative electrode, and a separator disposed between the positive and negative electrode. The cover plate assembly further includes a terminal post 3, which has a terminal post hole on the cover plate 2. The terminal post 3 passes through the terminal post hole, and one end of the terminal post 3 is electrically connected to the electrode assembly 6 inside the housing 1. The other end of the terminal post 3 faces the outside of the housing 1 and is used to connect with other battery cells or external circuits.

[0086] In one embodiment, the cover plate assembly further includes an explosion-proof valve 4, which is disposed on the cover plate 2 and is adapted to open when the air pressure inside the battery cell reaches a preset value, so as to discharge the high-temperature and high-pressure flue gas inside the battery cell and prevent the battery cell from exploding.

[0087] In one embodiment, the cover plate 2 is also provided with an injection hole 5, which is used to inject electrolyte into the cell.

[0088] The following examples illustrate the impact of different parameter values ​​on cell performance. The test results of the examples and comparative examples are shown in Table 1.

[0089] Table 1

[0090]

[0091] As can be seen from Table 1, for the battery cells of Examples 1 to 5, all parameters are within the range defined in this application, and no failures occurred after the battery cells were processed and assembled, indicating that the battery cells have good performance and meet the requirements.

[0092] For the battery cell of Comparative Example 1, the value of h3 / t is 0.48, which is less than 0.5 and not within the range of 0.5 to 0.9 as defined in this application. Compared with the stress test of the cover plate of the same thickness without reinforcement, the strength is slightly worse. This indicates that when h3 / t is less than 0.5, the residual thickness corresponding to the recessed part 2022 is too small, the structural strength of this part is too small, and the recessed depth of the recessed part 2022 is too large. Even the reinforcement structure formed by the recessed part 2022 and the rib 2021 is not enough to compensate for the loss of cover plate strength caused by the excessive recessed depth of the recessed part 2022. The reliability of the cover plate 2 is poor.

[0093] For the battery cell of Comparative Example 2, the value of e is 0.6 mm, which is greater than 0.5 mm and is not within the range of 0 ± 0.5 mm as defined in this application. During the welding of the casing, blasting points and incomplete welds occurred, and the welding was unqualified. This indicates that when e is not within the range of 0 to 0.5 mm, welding problems will occur during the welding of the casing.

[0094] For the battery cell of Comparative Example 3, the value of g1 is 0.02 mm, which is less than 0.03 mm and not within the range of 0.03 mm to 0.3 mm as defined in this application. This makes it difficult to assemble the cover during production on the production line. It can be seen that when g1 is not within the range of 0.03 mm to 0.3 mm as defined in this application, it is difficult to ensure that the cover assembly can be smoothly assembled with the housing.

[0095] For the battery cell of Comparative Example 4, the value of S1 / S2 is 0.78, which is less than 0.8. For the battery cell of Comparative Example 5, the value of S1 / S2 is 1.31, which is greater than 1.3. The S1 / S2 values ​​of Comparative Example 4 and Comparative Example 5 are not within the range of 0.8 to 1.3 as defined in this application. During the stamping of the cover plate 2, the rib 2021 cannot be formed. It can be seen that if S1 / S2 is too large or too small, the rib 2021 will not be formed. Therefore, by limiting the value of S1 / S2 to the range of 0.8 to 1.3, the recessed part 2022 and the rib 2021 can be formed smoothly, thereby effectively improving the structural strength and reliability of the cover plate 2.

[0096] The battery cell in this embodiment improves the processing yield and structural reliability of the cover plate 2 while ensuring the structural strength of the cover plate 2, ensuring the welding strength of the cover, and improving the assembly and welding yield of the cover, thereby achieving lightweighting and reducing material costs.

[0097] According to an embodiment of the present invention, another aspect provides a battery pack, comprising: a housing and the aforementioned battery cells, wherein the battery cells are disposed within the housing. The number of battery cells is plurality of them.

[0098] Optionally, the battery cell is a lithium-ion battery cell.

[0099] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. An electric cell, characterized by, The application relates to a shell, which has an open end, and a cover plate assembly arranged at the open end of the shell. The cover plate assembly comprises a cover plate, which comprises a cover plate body, a reinforcing portion and a lap joint portion. The cover plate body has a first center line extending along the thickness direction thereof. The reinforcing portion is connected to the first outer peripheral surface.

2. The electric cell of claim 1, wherein, The lap joint portion is connected to the second outer peripheral surface. The reinforcing portion is provided with a protruding rib and a recess on the side facing the inner cavity of the shell along the thickness direction.

3. The electric cell of claim 1, wherein, The protruding rib is connected to the lap joint portion. The recess is connected between the protruding rib and the cover plate body.

4. The electric cell of claim 1, wherein, The protruding rib is located in the inner cavity of the shell.

5. The electric cell of claim 1, wherein, The lap joint portion overlaps the first end surface.

6. The electric cell of claim 5, wherein, The thickness of the cover plate body is t along the thickness direction.

7. The electric cell of claim 5, wherein, The difference between the thickness of the cover plate body and the recess depth is h3.

8. The electric cell of claim 7, wherein, The relationship between h3 and t satisfies the formula: 0.5 <= h3 / t <= 0.

9. The value range of t is: 0.5 mm <= t <= 10 mm.

9. The electric cell of any one of claims 1 to 8, wherein, The value range of h3 is: 0.8 mm <= h3 <= 9 mm. The lap joint portion has a third outer peripheral surface facing away from the first center line along the direction perpendicular to the first center line. The vertical distance between the third outer peripheral surface and the outer wall surface of the shell is e. The value range of e is: 0 mm <= e <= 0.5 mm. The protruding rib and the shell are gap-fitted along the direction perpendicular to the first center line. The distance between the outer wall of the protruding rib and the inner wall of the shell is g1. The value range of g1 is: 0.03 mm <= g1 <= 0.3 mm. The size of the protruding rib along the thickness direction is h2. The value range of h2 is: 0.4 mm <= h2 <= 10 mm. The recess is an annular groove arranged around the cover plate body. The protruding rib is a convex ring connected between the annular groove and the lap joint portion. The cross-sectional area of the recess is S1, and the cross-sectional area of the protruding rib is S2. The relationship between S1 and S2 satisfies the formula: 0.8 <= S1 / S2 <= 1.

3. The outer peripheral wall of the protruding rib is a first side surface. The end surface of the protruding rib facing away from the cover plate body along the thickness direction is a second end surface. The included angle between the first side surface and the second end surface is an obtuse angle. The value range of B is: 92 <= B <= 105. The second end surface is annular, and the ring width of the annular second end surface is w1. The value range of w1 is: 0.3 mm <= w1 <= 10 mm. The size of the lap joint portion along the thickness direction is h1. The value range of h1 is: 0.5 mm <= h1 <= 10 mm. And / or, a wall thickness of the housing is w2, wherein w2 is in a range from 0.4 mm to 1.0 mm.

10. A battery pack, characterized by, Comprising: a box; the electric cell of any one of claims 1 to 9, disposed within the box.

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