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 with an open end, and the end face of the open end is a first end face; a cover plate assembly is arranged at the open end of the shell, and the cover plate assembly comprises a cover plate, the cover plate comprises a cover plate body, a reinforcing ring part and a lap joint ring part, the reinforcing ring part is connected to the outer circumferential side of the cover plate body in a surrounding manner, the upper surface of the reinforcing ring part is provided with a groove, the lower surface of the reinforcing ring part is provided with a convex rib corresponding to the groove, the convex rib extends into the inner cavity of the shell and is in gap cooperation with the side wall of the shell, and the lap joint ring part is connected to the outer circumferential side of the reinforcing ring part in a surrounding manner and is lapped on the first end face; the size of the bottom wall of the groove along the ring width direction of the reinforcing ring part is w1, and the recess depth of the groove along the up-down direction is h3, wherein the relationship between w1 and h3 satisfies the formula: 0.3 <= w1 / h3 <= 0.8. On the basis of strengthening the structural strength of the cover plate, the material cost and the weight of the battery cell are reduced, and the battery cell is lightened.

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 particularly important. 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 bumpy and vibrating environments, the cover area is subjected to significant shear force impacts. If the cover is not strong enough, it can lead to failure in weak areas such as the welded joints of the casing.

[0003] Existing cover plates are flat and have poor structural strength. Their strength is typically improved by increasing their thickness, but this also increases material costs and cell weight. Furthermore, to improve the assembly and welding yield of the cover plate and housing, stepped structures are usually added to the relatively narrow sidewalls of the housing to match the cover plate. However, the wall thickness of the sidewalls with stepped structures is greater than that of those without, making it impossible to achieve uniform wall thickness across all sidewalls of the housing. This complicates manufacturing and also increases material costs and cell weight. 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 comprising a cover plate, the cover plate comprising a cover plate body, a reinforcing ring portion and an overlapping ring portion, the reinforcing ring portion being connected around the outer periphery of the cover plate body, the upper surface of the reinforcing ring portion having a groove, the lower surface of the reinforcing ring portion having a rib corresponding to the groove, the rib extending into the inner cavity of the housing and having a clearance fit with the side wall of the housing, the overlapping ring portion being connected around the outer periphery of the reinforcing ring portion and overlapping the first end face; the bottom wall of the groove having a dimension w1 along the circumferential width direction of the reinforcing ring portion, the groove having a recess depth h3 along the vertical direction, wherein w1 and h3 satisfy the relationship: 0.3≤w1 / h3≤0.8.

[0006] Beneficial effects: By setting a reinforcing ring between the cover plate body and the overlapping ring, with one side of the reinforcing ring having a groove and the other side having a rib, the cover plate adopts a groove design around its perimeter, forming an alternating concave-convex structure. This strengthens the structural strength of the cover plate, reduces material usage, saves costs, and reduces its weight. The ribs and grooves are correspondingly positioned, facilitating stamping. Furthermore, by limiting the ratio of groove width to groove depth, w1 / h3, to within the range of 0.3 to 0.8, the structural strength of the punch is ensured, thereby guaranteeing the forming accuracy of the groove and ensuring smooth groove forming. The groove also provides sufficient reinforcement to the structural strength of the cover plate. Finally, the cover plate directly overlaps the opening end of the shell through the overlapping ring at its edge. The ribs connected to the overlapping rings extend into the inner cavity of the housing and fit with the side wall of the housing with a clearance. The ribs are close to the side wall of the housing and can play a certain guiding and positioning role during the assembly of the cover plate and the housing. After the cover plate is assembled, the ribs and the inner wall of the housing limit each other to prevent the cover plate from falling off, which facilitates the subsequent welding of the cover plate and improves the assembly and welding yield. It can also avoid the need to process the stepped structure on the side wall of the housing to support the cover plate, ensure the uniformity of the wall thickness of all side walls of the housing, facilitate the processing and forming of the housing, and reduce the material cost and weight of the housing. Thus, while strengthening the structural strength of the cover plate and the welding strength of the cover plate, the thickness of the cover plate is reduced, the processing yield and structural reliability of the cover plate are improved, the assembly and welding yield of the cover plate is improved, the material cost and weight of the battery cell are reduced, and it is conducive to achieving lightweighting.

[0007] In one optional implementation, the value range of w1 is: 0.6 mm ≤ w1 ≤ 30 mm;

[0008] And / or, the value range of h3 is: 0.75 mm ≤ h3 ≤ 100 mm.

[0009] Beneficial effects: By limiting w1 to a value within the range of 0.6 mm to 30 mm, it is possible to ensure that the punch used for processing the groove has sufficient thickness and structural strength, reduce the possibility of wear and cracking, thereby ensuring the forming accuracy of the groove, ensuring smooth forming of the groove, improving the processing yield, and avoiding the groove occupying too much space on the surface of the cover plate, leaving enough space for the arrangement of other structures on the cover plate, and improving the reliability of the cover plate.

[0010] And / or, by limiting h3 to a value between 0.75 mm and 100 mm, the groove has a reasonable groove depth, which can not only ensure sufficient reinforcement of the structural strength of the cover plate, but also reduce the processing difficulty of the groove, ensure smooth groove formation, and avoid the corresponding ribs occupying too much space in the inner cavity of the shell, thereby helping to improve the energy density of the battery cell.

[0011] In one optional embodiment, the upper surface of the reinforcing ring is flush with the upper surface of the cover plate body, the distance between the upper and lower surfaces of the reinforcing ring is h4, and the thickness of the cover plate body in the vertical direction is t, wherein h4, t and h3 satisfy the relationship: 0.3≤(h4-h3) / t≤1.5.

[0012] Beneficial effects: It can ensure the structural strength of the reinforcing ring itself and ensure that the reinforcing ring has a sufficient reinforcing effect on the structural strength of the cover plate, and it can also ensure the smooth forming of the ribs and grooves, thus improving the processing yield.

[0013] In one alternative implementation, h4 and t satisfy the relationship: 1 < h4 / t ≤ 5.

[0014] Beneficial effects: It can ensure that the reinforcing ring has ribs protruding from the lower surface of the cover plate body, thereby effectively increasing the structural strength of the cover plate and ensuring the relative stability of the cover plate after assembly with the shell. It can also avoid the cover plate cracking due to insufficient material flow space during stamping, thereby improving the processing yield.

[0015] In one optional implementation, the value of h4 is in the range of: 0.5 mm < h4 ≤ 50 mm;

[0016] And / or, the range of t is: 0.5mm≤t≤10mm.

[0017] Beneficial effects: By limiting h4 to be greater than 0.5 mm and less than or equal to 50 mm, it can be ensured that the reinforcing ring has a rib protruding from the lower surface of the cover plate body, thereby effectively increasing the structural strength of the cover plate and ensuring the relative stability of the cover plate after assembly with the shell. It can also avoid the cover plate cracking due to insufficient material flow space during stamping, thereby improving the processing yield of the cover plate.

[0018] And / or, by limiting t to a value between 0.5mm and 10mm, 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.

[0019] In one alternative embodiment, the groove is at least a portion of an annular groove circumferentially surrounding the cover plate body, and the rib is at least a portion of a convex ring circumferentially surrounding the cover plate body.

[0020] Beneficial effects: By setting the groove to be at least part of an annular groove and the rib to be at least part of a convex ring, it is convenient to process and form the groove 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.

[0021] In one optional embodiment, the upper surface of the overlapping ring is flush with the upper surface of the reinforcing ring. On the plane where the upper surface of the overlapping ring is located, the distance between the edge of the groove near the overlapping ring and the outer peripheral edge of the overlapping ring is E, wherein the value of E is in the range of 2 mm ≤ E ≤ 30 mm.

[0022] And / or, the sidewall of the groove near the cover plate body is the first sidewall, and the angle between the first sidewall and the bottom wall is B, wherein the value of B is in the range of 92°≤B≤150°;

[0023] And / or, the gap between the outer peripheral wall of the rib and the inner wall of the shell is g1, wherein the value of g1 is in the range of 0.03 mm ≤ g1 ≤ 0.3 mm.

[0024] Beneficial effects: By limiting E to a value within the range of 2 mm to 30 mm, sufficient covering space is reserved at the upper surface edge of the cover plate for the insulating film. This can prevent the insulating film from curling up after being folded and covered, thereby improving the reliability of the insulating film and customer satisfaction. It can also prevent the insulating film from occupying too much space on the cover plate, ensuring that the cover plate has sufficient arrangement space and improving the reliability of cover plate 2.

[0025] And / or, by limiting B to a value between 92° and 150°, the angle between the first sidewall and the bottom wall of the groove is obtuse, and the cross-section of the groove is trapezoidal, which facilitates the demolding of the mold after stamping, which is beneficial to improving product yield and processing efficiency. It can also prevent the groove wall from being scratched during the stamping and demolding of the cover plate, thus ensuring the appearance quality and avoiding stress concentration at the scratches that could cause cracking or deformation. Furthermore, it can prevent the groove from occupying too much space on the cover plate, thus ensuring the reasonable arrangement of other structures on the cover plate and improving the reliability of the cover plate.

[0026] 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 plate assembly and the shell, guaranteeing the smooth insertion of the cover plate assembly into the shell. It also ensures that the rib can play a good guiding role during the insertion of the cover plate assembly into the shell, and provide a certain positioning and support role after the cover plate assembly is inserted into the shell. This prevents the cover plate assembly from being too loose after assembly with the shell, improves the relative stability between the cover plate and the shell, prevents the cover plate from falling off the shell, facilitates the subsequent welding between the shell and the cover plate, and helps to improve the welding yield.

[0027] In one optional embodiment, the battery cell further includes an electrode assembly and a connecting piece disposed in the inner cavity of the housing. The connecting piece is connected to the side of the electrode assembly facing the cover plate. The distance between the rib and the connecting piece in the vertical direction is g2, wherein the value of g2 is in the range of 2 mm ≤ g2 ≤ 10 mm.

[0028] And / or, the cover plate body is provided with a reinforcing structure, and the distance between the rib and the reinforcing structure is g3, wherein the value of g3 is in the range of 3 mm ≤ g3 ≤ 30 mm.

[0029] Beneficial effects: By limiting g2 to a value between 2 mm and 10 mm, a reasonable gap is maintained between the rib and the connecting piece in the vertical direction. This can prevent the rib and the connecting piece from overlapping and causing a short circuit between the cover plate and the connecting piece, and prevent the metal wire generated by the friction between the rib and the connecting piece from falling into the inner cavity of the shell, thereby ensuring the reliability and safety of the battery cell. It can also avoid wasting the internal space of the battery cell, which is conducive to increasing the capacity of the battery cell.

[0030] And / or, by limiting g3 to a value between 3 mm and 30 mm, a reasonable spacing is achieved between the reinforcing ring and the reinforcing structure. This avoids the overlap of material flow space during stamping, thus preventing stress concentration and cracking, ensuring the smooth forming of the cover plate, and also ensures that the cover plate provides sufficient arrangement space, improving the reliability of the cover plate.

[0031] In one optional embodiment, the dimension of the overlapping ring portion in the vertical direction is h1, wherein the value of h1 ranges from 0.5 mm to h1 to 10 mm.

[0032] And / or, along the vertical direction, the distance between the lower surface of the rib and the lower surface of the overlapping ring is h2, wherein the value of h2 is in the range of 0.4 mm ≤ h2 ≤ 10 mm.

[0033] Beneficial effects: By limiting h1 to a value between 0.5 mm and 10 mm, the overlapping ring has a reasonable thickness, which can ensure that the overlapping ring has sufficient structural strength and provide sufficient space for the welding pool during the welding of the shell and cover along the thickness direction, thereby ensuring welding strength, ensuring the stability and reliability of the connection between the cover and the shell after welding, avoiding material waste, reducing the weight of the cover, and facilitating the lightweighting of the battery cell;

[0034] And / or, by limiting h2 to a value between 0.4 mm and 10 mm, the rib protrudes downward by a reasonable amount relative to the overlapping ring. This ensures a stable fit between the cover assembly and the housing during assembly, prevents the cover assembly from falling off the housing, facilitates assembly and welding on the production line, improves assembly efficiency, ensures the rib can be formed smoothly, avoids material waste, reduces weight, and saves costs.

[0035] 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

[0036] 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.

[0037] Figure 1 This is a top view of a battery cell according to an embodiment of the present invention;

[0038] Figure 2 for Figure 1 A cross-sectional view along the AA direction;

[0039] Figure 3 for Figure 2 A magnified view of part of C;

[0040] Figure 4 for Figure 2 A cross-sectional view along the DD direction;

[0041] Figure 5 for Figure 4 A magnified view of part of F;

[0042] Figure 6 This is a schematic diagram of the structure of a cover plate according to an embodiment of the present invention;

[0043] Figure 7 for Figure 6 The diagram shows the structure of the cover plate from the bottom view.

[0044] Figure 8 for Figure 7 A magnified view of part of J;

[0045] Figure 9 This is a schematic diagram of the structure of a shell according to an embodiment of the present invention;

[0046] Figure 10 for Figure 9 A magnified view of a portion of K;

[0047] Figure 11 A top view of the battery cell before the improvement;

[0048] Figure 12 for Figure 11 Cross-sectional view along the MM direction;

[0049] Figure 13 for Figure 12 A magnified view of a portion of Q;

[0050] Figure 14 for Figure 12 A cross-sectional view along the NN direction;

[0051] Figure 15 for Figure 14 A magnified view of a portion of the radius R;

[0052] Figure 16 This is a schematic diagram of the shell structure before the improvement.

[0053] Figure 17 for Figure 16 A magnified view of a portion of the U-shaped area;

[0054] Figure 18 This is a schematic diagram of another type of cover plate before the improvement;

[0055] Figure 19 for Figure 18 The diagram shows a partially enlarged cross-section of the cover plate and the shell in contact.

[0056] Explanation of reference numerals in the attached figures:

[0057] 1. Housing; 101. First end face; 102. Limiting surface; 111. First wall; 112. Second wall; 113. Third wall; 114. Fourth wall; 2. Cover plate; 201. Cover plate body; 2011. Reinforcing structure; 2012. Mounting hole; 202. Reinforcing ring; 2021. Groove; 2022. Rib; 2023. Bottom wall; 2024. First side wall; 203. Overlapping ring; 3. Pole post; 4. Explosion-proof valve; 5. Injection hole; 6. Pole assembly; 7. Connecting piece; 8. Insulating film. Detailed Implementation

[0058] 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.

[0059] Lithium-ion batteries are a commonly used type of battery. With the increasing maturity of lithium-ion battery technology, they are widely used as power batteries in electric vehicles and energy storage, leading to increasingly stringent requirements for performance and safety. The battery cell, as the basic unit of the battery pack, is sealed by a cover plate 2 and a shell 1, encapsulating the electrode assembly 6 internally. A lower plastic sheet (PP material) holds the electrode assembly 6 in place. After the battery pack is installed in a vehicle, prolonged vibration and bumps on the vehicle can cause significant shear force impact on the cell cover. Insufficient strength of the cover plate 2 can lead to damage and failure in weak areas such as the explosion-proof valve 4 and the welded joints of the shell cover. Therefore, the cover plate requires a certain structural strength.

[0060] In related technologies, the cover plate is flat and has poor structural strength. Its strength is typically improved by increasing the thickness of the cover plate, but this also increases the material cost of the cover plate and the weight of the battery cell. Furthermore, to improve the assembly and welding yield between the cover plate and the housing, a stepped structure that mates with the cover plate is usually provided on the relatively narrow sidewall of the housing, such as... Figure 13 , Figure 16 and Figure 17 As shown, the sidewalls of the housing 1, which are arranged opposite each other along the length direction, are constructed with stepped structures to form limiting surfaces 102. The limiting surfaces 102 are used to support the cover plate 2 and prevent the cover plate 2 from falling off. Figures 14 to 15 As shown, if the sidewalls of the shell 1, which are arranged opposite each other along the width direction, do not have stepped structures, then the wall thickness of the sidewalls with stepped structures will be greater than that of the sidewalls without stepped structures. This results in the wall thickness of all the sidewalls of the shell not being completely uniform. Figure 13 and Figure 15 The inconsistent wall thickness of the sidewalls shown makes the casing manufacturing process complex and also increases the cost of casing materials and the weight of the battery cell.

[0061] In summary, the battery cells in the relevant technologies suffer from problems such as poor strength of the cover plate structure, high material cost, and large weight.

[0062] The following is combined Figures 1 to 19 The following describes embodiments of the present invention.

[0063] According to embodiments of the present invention, in one aspect, a battery cell is provided, such as... Figures 1 to 10 As shown, the battery cell includes: 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, and the cover plate assembly includes a cover plate 2, which includes a cover plate body 201, a reinforcing ring portion 202, and an overlapping ring portion 203. The reinforcing ring portion 202 is connected around the outer periphery of the cover plate body 201. The upper surface of the reinforcing ring portion 202 has a groove 2021, and the lower surface of the reinforcing ring portion 202 has a rib 2022 corresponding to the groove 2021. 2022 extends into the inner cavity of the housing 1 and is clearance-fitted with the side wall of the housing 1. The overlapping ring 203 is connected around the outer periphery of the reinforcing ring 202 and overlaps the first end face 101. The bottom wall 2023 of the groove 2021 has a dimension w1 along the ring width direction of the reinforcing ring 202, and the recess depth of the groove 2021 along the vertical direction is h3. The relationship between w1 and h3 is: 0.3≤w1 / h3≤0.8. The units of w1 and h3 are both mm.

[0064] The up and down directions refer to Figures 2 to 5 The direction indicated by the middle arrow, "up and down," is in the same direction as the thickness direction of the cover plate 2; the upper surface of the reinforcing ring 202 refers to the surface of the reinforcing ring 202 facing away from the inner cavity of the housing 1, that is, the surface of the cover plate 2 facing away from the inner cavity of the housing 1, specifically... Figures 2 to 5 The surface in the direction indicated by the middle arrow ("up"); the lower surface of the reinforcing ring 202 refers to the surface of the reinforcing ring 202 facing the inner cavity of the housing 1, that is, the surface of the cover plate 2 facing the inner cavity of the housing 1, specifically... Figures 2 to 5 The surface in the direction indicated by the middle arrow, which points to "down".

[0065] The division of the cover plate body 201, the reinforcing ring 202, and the overlapping ring 203 is as follows: Figure 3 As shown by the dotted lines, it should be noted that the dotted lines are only for illustration and do not actually exist; the cover body 201 is located in the central area of ​​the entire cover 2, and the cover body 201 has a first center line extending in the vertical direction. The center lines of the reinforcing ring 202 and the overlapping ring 203 are both collinear with the first center line; along the direction perpendicular to the first center line, the circumferential edge of the cover body 201 away from the first center line is the outer peripheral side of the cover body 201, and the circumferential edge of the overlapping ring 203 away from the cover body 201 is the outer peripheral side of the overlapping ring 203.

[0066] It should also be noted that the cover plate 2 in this embodiment is stamped from a plate-shaped raw material. After stamping, grooves 2021 and ribs 2022 are formed to form a reinforcing ring 202, thereby forming an alternating concave-convex structure on the cover plate 2, that is, forming reinforcing ribs on the cover plate 2, increasing the structural strength of the cover plate 2, improving the bending resistance of the cover plate 2, and the grooves 2021 and / or ribs 2022 can also disperse stress along their own extension direction to avoid stress concentration. The reinforcing ring 202 can disperse the pressure borne by the edge of the cover plate 2 to the entire cover plate plane, reduce the warping of the cover plate 2, and improve the deformation resistance. Compared with the traditional method of increasing the strength by increasing the thickness of the cover plate 2, it can effectively reduce the material used for the cover plate.

[0067] The opening side of the groove 2021 faces away from the housing 1. The groove 2021 is formed by stamping with a punch. The vertical depth h3 of the groove 2021 is equal to the vertical distance (i.e., groove depth) between the upper surface of the reinforcing ring 202 and the bottom wall 2023. The groove 2021 is formed by recessing a portion of the upper surface of the reinforcing ring 202. The dimension of the groove 2021 along the ring width direction of the reinforcing ring 202 (i.e., groove width) is less than or equal to the ring width of the reinforcing ring 202. The ring width direction of the reinforcing ring 202 is perpendicular to the extension direction of the first center line. If w1 / h3 is less than 0.3... If the ratio of the width to the depth of the groove 2021 is too small, the punch will have a narrow and long structure, resulting in poor structural strength and easy wear and cracking. This will lead to poor forming accuracy of the groove 2021, or even make it difficult to form. If w1 / h3 is greater than 0.8, the ratio of the width to the depth of the groove 2021 will be too large. The cover plate 2 will be close to the original flat plate structure. The bottom of the wide and shallow groove is more prone to local buckling deformation under pressure. Stress concentration is likely to occur at the junction of the groove bottom and the sidewall, which is prone to cracking or breakage. Therefore, the effect of strengthening the structural strength of the cover plate is not obvious.

[0068] Using the battery cell of this embodiment, a reinforcing ring 202 is provided between the cover plate body 201 and the overlapping ring 203. One side of the reinforcing ring 202 has a groove 2021, and the other side has a rib 2022. This allows the cover plate 2 to have a recessed groove design around its perimeter, forming an alternating concave-convex structure. This strengthens the structural strength of the cover plate 2, reduces material usage, saves costs, and reduces the weight of the cover plate 2. The rib 2022 corresponds to the groove 2021, facilitating stamping. Furthermore, by limiting the ratio w1 / h3 between the groove width and depth of the groove 2021 to within the range of 0.3 to 0.8, the structural strength of the punch is ensured, thereby guaranteeing the forming accuracy of the groove 2021 and ensuring its smooth forming. The groove 2021 also provides sufficient reinforcement to the structural strength of the cover plate 2. Additionally, the overlapping ring 203 at the edge of the cover plate 2 further enhances its structural strength. The rib 2022, which is directly attached to the open end of the housing 1 and connected to the overlapping ring 203, extends into the inner cavity of the housing 1 and is in clearance fit with the side wall of the housing 1. The rib 2022 is close to the side wall of the housing 1 and can play a certain guiding and positioning role during the assembly of the cover plate 2 and the housing 1. After the cover is assembled, the rib 2022 and the inner wall of the housing 1 mutually limit each other to prevent the cover plate 2 from falling off, which facilitates the subsequent welding of the cover and improves the assembly and welding yield. It can also avoid processing the stepped structure on the side wall of the housing 1 to support the cover plate 2, ensuring the uniformity of the wall thickness of all side walls of the housing 1, which facilitates the processing and forming of the housing 1, and can reduce the material cost and weight of the housing 1. Thus, while strengthening the structural strength and welding strength of the cover plate 2, the thickness of the cover plate 2 is reduced, the processing yield and structural reliability of the cover plate 2 are improved, the assembly and welding yield of the cover is improved, the material cost and weight of the battery cell are reduced, and it is conducive to achieving lightweighting. 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.

[0069] Optionally, w1 / h3 can take any value from 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, or a value between any two values.

[0070] In one embodiment, the value of w1 ranges from 0.6 mm to 30 mm. It should be noted that w1 is the width of the groove 2021. If w1 is less than 0.6 mm, the groove width of 2021 is too small, and the corresponding stamping punch is too thin, making it prone to wear and cracking. This leads to poor forming accuracy of the groove 2021, or even difficulty in forming it. If w1 is greater than 30 mm, the groove width of 2021 is too large, occupying too much space on the cover plate 2. This results in insufficient space on the cover plate 2, affecting the layout of other structures such as the pole post 3 and the injection hole 5 on the cover plate 2. Therefore, by limiting w1 to a value within the range of 0.6 mm to 30 mm, it is possible to ensure that the punch used to process the groove 2021 has sufficient thickness and structural strength, reduce the possibility of wear and cracking, thereby ensuring the forming accuracy of the groove 2021, ensuring the smooth forming of the groove 2021, improving the processing yield, and also to avoid the groove 2021 occupying too much space on the surface of the cover plate 2, reserving sufficient space for the arrangement of other structures on the cover plate 2, and improving the reliability of the cover plate 2.

[0071] Optionally, w1 can be any value among 0.6 mm, 1 mm, 3 mm, 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm, 28 mm, and 30 mm, or a value between any two of these values.

[0072] It should be noted that the cover plate assembly also includes a pole post 3, which is disposed on the cover plate 2 and electrically connected to the tabs on the electrode group 6; the cover plate 2 is also provided with an injection hole 5, which is a through hole that penetrates the cover plate 2 in the vertical direction. The injection hole 5 is used to inject electrolyte into the cell, and the injection hole 5 is sealed by a sealing pin when it is not necessary to inject electrolyte into the cell.

[0073] In one embodiment, the value of h3 ranges from 0.75 mm to 100 mm. It should be noted that h3 is the groove depth of the groove 2021. If h3 is less than 0.75 mm, the groove depth of the groove 2021 is too small, the upper surface of the cover plate 2 is close to a plane, and the reinforcing effect of the groove 2021 on the structure of the cover plate 2 is not significant. If h3 is greater than 100 mm, the groove depth of the groove 2021 is too large, and the extension distance of the groove 2021 in the vertical direction is too large. During the stamping process, insufficient material may occur, leading to excessively thin sidewalls or bottom walls of the groove 2021, or even breakage. This makes processing more difficult. Correspondingly, the size of the rib 2022 extending into the inner cavity of the housing 1 is too large, occupying too much space inside the cell in the vertical direction, affecting the arrangement of components such as the electrode group inside the housing 1, and is not conducive to improving the energy density of the cell. Therefore, by limiting h3 to a value between 0.75 mm and 100 mm, the groove 2021 is guaranteed to have a reasonable groove depth. This ensures that the structural strength of the cover plate 2 is sufficiently reinforced, reduces the processing difficulty of the groove 2021, ensures that the groove 2021 is formed smoothly, and avoids the corresponding rib 2022 occupying too much space in the inner cavity of the shell 1, thereby helping to improve the energy density of the battery cell.

[0074] Optionally, h3 can be any value among 0.75 mm, 1 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, and 100 mm, or a value between any two of these values.

[0075] In one embodiment, further combination Figure 3 and Figure 5 As shown, the upper surface of the reinforcing ring 202 is flush with the upper surface of the cover plate body 201. The distance between the upper and lower surfaces of the reinforcing ring 202 is h4, and the thickness of the cover plate body 201 along the vertical direction is t. h4, t, and h3 satisfy the relationship: 0.3 ≤ (h4 - h3) / t ≤ 1.5. Here, the upper surface refers to... Figure 3 and Figure 5 The surface indicated by the middle arrow pointing "up" is the surface in the direction of the arrow; the surface below refers to... Figure 3 and Figure 5 The surface in the direction indicated by the middle arrow ("down"); h4, t, and h3 are all in mm.

[0076] It should be noted that t is the thickness of the cover plate body 201, and h4-h3 is the vertical distance between the bottom wall 2023 of the groove 2021 and the lower surface of the rib 2022 along the vertical direction, that is, the thickness of the remaining solid part of the reinforcing ring 202 corresponding to the groove 2021 along the vertical direction. If (h4-h3) / t is less than 0.3, the thickness of the remaining solid part is too small relative to the thickness of the cover plate body 201, its own structural strength is poor, and the strengthening effect on the structural strength of the cover plate 2 is not obvious. The rib 2022 and the groove 2021 are stamped from sheet metal, and the remaining solid part of the reinforcing ring 202 corresponding to the groove 2021 is formed by extrusion. If (h4-h3) / t is greater than 1.5, the thickness of the remaining solid part is too large relative to the thickness of the cover plate body 201, requiring more material, and the material provided by the sheet metal is insufficient, making processing and forming difficult.

[0077] Therefore, by limiting the value of (h4-h3) / t to the range of 0.3 to 1.5, it is possible to ensure the structural strength of the reinforcing ring 202 itself and to ensure that the reinforcing ring 202 has a sufficient reinforcing effect on the structural strength of the cover plate 2, while also ensuring the smooth forming of the rib 2022 and the groove 2021, thereby improving the processing yield.

[0078] Optionally, (h4-h3) / t can take any value from 0.3, 0.5, 0.7, 1.0, 1.2, 1.5 or any value between any two values.

[0079] In one embodiment, h4 and t satisfy the relationship: 1 < h4 / t ≤ 5. It should be noted that after stamping, the reinforcing ring 202 forms a groove 2021 and a rib 2022. The reinforcing ring 202 is annular, and at least a portion of the upper surface of the annulus is concave downwards to form the groove 2021. The entire lower surface of the reinforcing ring 202 protrudes downwards to form the rib 2022, that is, the rib 2022 protrudes downwards from the lower surface of the cover plate body 201. h4 is equal to the total thickness of the reinforcing ring 202 along the vertical direction. If h4 / t is less than or equal to 1, then the lower surface of the reinforcing ring 202 is located on the lower surface of the cover plate body 201. The upper side of the cover plate 2 or the lower surface of the cover plate body 201 are flush. The reinforcing ring 202 cannot form a protruding structure relative to the cover plate body 201, which is not effective in strengthening the structural strength of the cover plate 2. In addition, the fit between the reinforcing ring 202 and the side wall of the housing 1 in the vertical direction is insufficient. During the cell assembly process, the cover plate 2 is easy to fall off the housing 1, which is quite dangerous. If h4 / t is greater than 5, the total thickness of the reinforcing ring 202 is too large relative to the thickness of the cover plate body 201. There is insufficient space for material flow during stamping, and the cover plate 2 is easy to tear.

[0080] Therefore, by limiting h4 / t to be greater than 1 and less than or equal to 5, it can be ensured that the reinforcing ring 202 has a rib 2022 protruding from the lower surface of the cover plate body 201, thereby effectively increasing the structural strength of the cover plate 2 and ensuring the relative stability of the cover plate 2 after assembly with the shell 1. It can also avoid the cover plate 2 cracking due to insufficient material flow space during stamping, thereby improving the processing yield.

[0081] It should be noted that the lower limit of h4 / t is a value greater than 1 and can be infinitely close to 1. Optionally, the value of h4 / t can be any value among 1.01, 1.1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5, or a value between any two values.

[0082] 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.

[0083] 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.

[0084] In one embodiment, the value of h4 is in the range of 0.5 mm < h4 ≤ 50 mm. If h4 is less than or equal to 0.5 mm, the lower surface of the reinforcing ring 202 is located above the lower surface of the cover body 201 or flush with the lower surface of the cover body 201, which does not effectively strengthen the structural strength of the cover 2. Furthermore, the fit between the reinforcing ring 202 and the side wall of the housing 1 in the vertical direction is insufficient, and the cover 2 is prone to falling off the housing 1 during the cell assembly process. If h4 is greater than 50 mm, the total thickness of the reinforcing ring 202 is too large, resulting in insufficient material flow space during stamping, and the cover 2 is prone to tearing.

[0085] Therefore, by limiting h4 to be greater than 0.5 mm and less than or equal to 50 mm, it can be ensured that the reinforcing ring 202 has a rib 2022 protruding from the lower surface of the cover plate body 201, thereby effectively increasing the structural strength of the cover plate 2 and ensuring the relative stability of the cover plate 2 after assembly with the shell 1. It can also avoid the cover plate 2 cracking due to insufficient material flow space during stamping, thereby improving the processing yield of the cover plate 2.

[0086] Optionally, h4 can be any value among 0.505 mm, 0.55 mm, 1 mm, 5 mm, 10 mm, 20 mm, 30 mm, 40 mm, and 50 mm, or a value between any two of these values.

[0087] In one embodiment, the groove 2021 is at least a portion of an annular groove circumferentially surrounding the cover plate body 201, and the rib 2022 is at least a portion of a convex ring circumferentially surrounding the cover plate body 201. The annular groove and the convex ring are concentrically arranged. By setting the groove 2021 to be at least a portion of an annular groove and the rib 2022 to be at least a portion of a convex ring, the processing and forming of the groove 2021 and the rib 2022 are facilitated. The alternating concave and convex structure improves the structural strength of the entire edge of the cover plate 2, thereby increasing the overall structural strength of the cover plate 2. This facilitates reducing the thickness of the cover plate 2, ensuring structural strength while avoiding excessive material usage and weight, thus reducing material costs and the weight of the battery cell.

[0088] In one embodiment, the groove 2021 is an annular groove arranged around the cover plate body 201, and the rib 2022 is a convex ring arranged around the cover plate body 201. That is, the groove 2021 and the rib 2022 are each continuously surrounding the cover plate body 201, with good continuity and easy processing and forming.

[0089] Alternatively, in other embodiments, the groove 2021 is a part of an annular groove circumferentially arranged around the cover plate body 201, and the rib 2022 is a part of a convex ring circumferentially arranged around the cover plate body 201. That is, the groove 2021 is a partially unclosed annular groove along the circumference of the cover plate 2, and the rib 2022 is a partially unclosed convex ring along the circumference of the cover plate 2. Or, the groove 2021 is a plurality of groove segments intermittently surrounding the cover plate body 201, and the rib 2022 is a plurality of rib segments intermittently surrounding the cover plate body 201. In this case, the plurality of groove segments are all partial sections on the annular groove, and the plurality of rib segments are all partial sections on the convex ring. This can also achieve the effect of strengthening the structural strength of the cover plate 2.

[0090] In one embodiment, the upper surface of the overlapping ring portion 203 is flush with the upper surface of the reinforcing ring portion 202. On the plane containing the upper surface of the overlapping ring portion 203, the distance between the edge of the groove 2021 near the overlapping ring portion 203 and the outer peripheral edge of the overlapping ring portion 203 is E, where the value of E ranges from 2 mm to 30 mm. The upper surface refers to... Figure 5 The surface indicated by the middle arrow, pointing in the direction of "up," refers to the surface on the side facing away from the casing 1 along the vertical direction. It should be noted that after the casing 1 and cover plate 2 of the battery cell are assembled, an insulating film 8 needs to be wrapped around the outermost layer of the battery cell, such as... Figure 5 As shown, the insulating film 8 is bent from the side wall of the housing 1 to the upper surface of the cover plate 2. The upper surface of the overlapping ring 203 and the upper surface of the reinforcing ring 202, located in the area between the groove 2021 and the overlapping ring 203, are covered by the insulating film 8. Here, E is the ring width of the area of ​​the edge of the cover plate 2 that can cover the insulating film 8. If E is less than 2 mm, the area reserved for the insulating film 8 on the upper surface of the cover plate 2 is too narrow, and the insulating film 8 will curl up after being folded and covered, resulting in poor covering quality and causing customer dissatisfaction. If E is greater than 30 mm, the area reserved for the insulating film 8 on the upper surface of the cover plate 2 is too wide, occupying too much space on the upper surface of the cover plate 2, thereby squeezing the arrangement space of other structures on the cover plate 2, resulting in insufficient arrangement space for the cover plate 2 and affecting the performance of the cover plate 2.

[0091] Therefore, by limiting E to a value within the range of 2 mm to 30 mm, sufficient covering space is reserved at the upper surface edge of the cover plate 2 for the insulating film 8. This can prevent the insulating film 8 from curling up after being folded and covered, thereby improving the reliability of the insulating film 8 and customer satisfaction. It can also prevent the insulating film 8 from occupying too much space on the cover plate 2, ensuring that the cover plate 2 has sufficient arrangement space and improving the reliability of the cover plate 2.

[0092] Specifically, the groove 2021 is an annular groove. The edge of the groove 2021 near the overlapping ring 203 refers to the outer ring of the opening end of the groove 2021. The area between the outer ring of the opening end of the groove 2021 and the outer peripheral edge of the overlapping ring 203 is annular, and E is the ring width of the annular ring.

[0093] Optionally, E can be any value among 2 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm, or a value between any two of these values.

[0094] In one embodiment, the sidewall of the groove 2021 near the cover plate body 201 is a first sidewall 2024, and the included angle between the first sidewall 2024 and the bottom wall 2023 is B, wherein the value of B is in the range of 92°≤B≤150°. It should be noted that the groove 2021 is at least part of the annular groove arranged circumferentially around the cover plate 2. The groove 2021 has a first sidewall 2024 near the cover plate body 201 and a second sidewall near the overlapping ring 203. The groove 2021 is stamped and formed. After forming, a certain draft angle is required to pull the punch out of the groove 2021. B is the draft angle. If B is less than 92°, the draft angle is too small. The wall surface of the groove 2021 is easily scratched during stamping and demolding, which affects the appearance quality. The scratched area becomes a weak point in the structure. When under stress, stress concentration is likely to occur, and cracking or deformation is more likely to occur. If B is greater than 150°, the draft angle is too large. The annular width of the opening end of the groove 2021 is too large, which makes the space occupied by the groove 2021 on the cover plate 2 too large, affecting the arrangement of other structures on the cover plate 2.

[0095] Therefore, by limiting B to a value between 92° and 150°, the included angle between the first sidewall 2024 and the bottom wall 2023 of the groove 2021 is obtuse, and the cross-section of the groove 2021 is trapezoidal. This facilitates demolding after stamping, which is beneficial to improving product yield and processing efficiency. It also avoids scratching the wall of the groove 2021 during stamping and demolding of the cover plate 2, thus ensuring appearance quality and preventing stress concentration at scratches that could lead to cracking or deformation. Furthermore, it avoids the groove 2021 occupying too much space on the cover plate 2, thus ensuring the reasonable arrangement of other structures on the cover plate 2 and improving the reliability of the cover plate 2.

[0096] Optionally, the value of B can be any value among 92°, 100°, 110°, 120°, 130°, 140°, and 150°, or a value between any two values.

[0097] In one embodiment, the second sidewall on the side of the groove 2021 near the overlapping ring 203 is inclined relative to the bottom wall 2023, and the included angle between the second sidewall and the bottom wall 2023 is an obtuse angle, which further ensures that the stamping die can be demolded smoothly.

[0098] In one embodiment, the first sidewall 2024 and the second sidewall are respectively connected to the upper surface of the cover plate 2 by a rounded transition, which facilitates stamping and can avoid stress concentration at the corner, further improving the processing yield and the reliability of the cover plate 2.

[0099] In one embodiment, the rib 2022 is in the shape of a convex ring. The rib 2022 has an outer peripheral wall on the side away from the center of the convex ring and an inner peripheral wall on the side facing the center of the convex ring. The surface of the rib 2022 on the side away from the groove 2021 in the vertical direction is the lower surface of the reinforcing ring 202. The angles between the outer peripheral wall and the inner peripheral wall of the rib 2022 and the lower surface of the rib 2022 are both obtuse angles, which further facilitates the demolding of the stamping die.

[0100] It should be noted that the clearance fit between the rib 2022 and the side wall of the housing 1 means that the rib 2022 is close to the side wall of the housing 1 and there is a small gap between the rib 2022 and the side wall of the housing 1.

[0101] In one embodiment, further combination Figure 3 As shown, the gap between the outer peripheral wall of the rib 2022 and the inner wall of the shell 1 is g1, where 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 peripheral wall of rib 2022 refers to the side wall of rib 2022 facing the housing side wall it mates with, that is, the circumferential wall of rib 2022 facing away from the center of the convex ring; rib 2022 extends into the inner cavity of housing 1. By setting the rib 2022 and housing 1 to have a clearance fit, there is a small gap between the rib 2022 and the inner wall of housing 1. The rib 2022 is set close to the inner wall of housing, which can provide guidance for the cover plate assembly during the assembly of the cover plate assembly and housing. If g1 is less than 0.03 mm, the gap between the rib 2022 and the inner wall of housing 1 is too small, the rib 2022 is too close to the inner wall of housing 1, the cover plate assembly is too tight when assembled with housing 1, and the cover plate assembly is difficult to insert into the housing. If g1 is greater than 0.3 mm, the gap is too small. If the distance between the rib 2022 and the inner wall of the housing 1 is too large, the rib 2022 is too far from the inner wall of the housing 1, the rib 2022 cannot play a good guiding role in the process of the cover plate assembly entering the housing, the cover plate assembly is too loosely fitted to the housing 1, the relative stability between the cover plate 2 and the housing 1 is poor after assembly, and the cover plate 2 is easy to fall off the housing 1.

[0102] Therefore, by limiting g1 to a value between 0.03 mm and 0.3 mm, a reasonable gap size is achieved between the rib 2022 and the inner wall of the housing 1. This ensures that the rib 2022 can smoothly enter the housing 1 during the assembly of the cover plate assembly and the housing 1, guaranteeing the smooth installation of the cover plate assembly. It also ensures that the rib 2022 can play a good guiding role during the installation of the cover plate assembly and provide a certain positioning and support role after the cover plate assembly is installed. This prevents the cover plate assembly from being too loose after assembly with the housing 1, improves the relative stability between the cover plate 2 and the housing 1, prevents the cover plate 2 from falling off the housing 1, facilitates the subsequent welding between the housing 1 and the cover plate 2, and helps to improve the welding yield.

[0103] 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.

[0104] In one embodiment, further combination Figure 5 As shown, the battery cell also includes an electrode group 6 and a connecting piece 7 disposed in the inner cavity of the housing 1. The connecting piece 7 is connected to the side of the electrode group 6 facing the cover plate 2. The distance between the rib 2022 and the connecting piece 7 in the vertical direction is g2, wherein the value range of g2 is: 2 mm ≤ g2 ≤ 10 mm. It should be noted that the cover plate 2 has a mounting hole 2012, the pole post 3 passes through the mounting hole 2012, and a sealing insulating element is provided between the pole post 3 and the mounting hole 2012 to insulate the pole post 3 from the cover plate 2; the connecting piece 7 is a metal part, one side of the connecting piece 7 is welded to the pole lug on the pole group 6 and the other side is welded to the pole post 3, thereby realizing the electrical connection between the pole post 3 and the pole group 6. The connecting piece 7 and the cover plate 2 are spaced apart to avoid short circuit between the connecting piece 7 and the cover plate 2; the rib 2022 extends into the inner cavity of the housing 1. By setting the rib 2022 and the connecting piece 7 to be spaced apart in the vertical direction, it is possible to avoid short circuit between the connecting piece 7 and the rib 2022. g2 is equal to the distance between the lower surface of the rib 2022 and the upper surface of the connecting piece 7. If g2 is less than 2 If g2 is less than 10 mm, the distance between the rib 2022 and the connecting piece 7 is too small, which can easily lead to lap short circuits or even friction between the two causing metal wires to fall off. If the metal wires fall into the inner cavity of the shell, they will contaminate the electrolyte or electrode materials, resulting in a decrease in cell performance. If g2 is greater than 10 mm, the distance between the rib 2022 and the connecting piece 7 is too large, wasting the internal space of the cell and reducing the height of the electrode group 6 fixed to the connecting piece 7, thereby reducing the cell capacity.

[0105] Therefore, by limiting g2 to a value between 2 mm and 10 mm, a reasonable distance is maintained between the rib 2022 and the connecting piece 7 in the vertical direction. This can prevent the rib 2022 from overlapping with the connecting piece 7, which would cause a short circuit between the cover plate 2 and the connecting piece 7, and prevent the rib 2022 from rubbing against the connecting piece 7 and generating metal wires that fall into the inner cavity of the housing 1, thereby ensuring the reliability and safety of the battery cell. It can also avoid wasting the internal space of the battery cell and is conducive to increasing the capacity of the battery cell.

[0106] Optionally, g2 can be any value among 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.

[0107] It should be noted that the electrode group 6 includes a positive electrode plate, a negative electrode plate, and a diaphragm disposed between the positive electrode plate and the negative electrode plate; one end of the electrode post 3 is welded to the connecting piece 7 inside the housing 1, and the other end of the electrode post 3 faces the outside of the housing 1 for connection with other battery cells or external circuits.

[0108] In one embodiment, a reinforcing structure 2011 is constructed on the cover plate body 201, and the distance between the rib 2022 and the reinforcing structure 2011 is g3, wherein the value of g3 ranges from 3 mm to g3 to 30 mm. It should be noted that the reinforcing structure 2011 is any reinforcing part on the cover plate 2 other than the reinforcing ring 202, and can be other protrusions or grooves adjacent to the rib 2022. Optionally, it can be further combined with… Figure 5 and Figure 8 As shown, the cover plate 2 has a mounting hole 2012 through which the pole post 3 passes. A ring groove is provided around the mounting hole 2012, which is a reinforcing structure 2011 used to improve the structural strength around the mounting hole 2012, ensuring that the mounting hole 2012 does not deform, and further increasing the reliability of the cover plate 2. Of course, the reinforcing structure 2011 can also be a ring-shaped protrusion or annular groove structure around the explosion-proof valve 4 and / or the injection hole 5, or a strip-shaped protrusion or strip-shaped groove structure provided on the cover plate body 201. The ring width of the protruding ring where the rib 2022 is located is greater than or equal to the ring width of the annular groove where the groove 2021 is located. Therefore, the distance between the rib 2022 and the reinforcing structure 2011 is the minimum distance between the reinforcing ring 202 and the reinforcing structure 2011. Both the reinforcing structure 2011 and the rib 2022 are formed by stamping. If g3 is less than 3... If g3 is greater than 30 mm, the distance between the rib 2022 and the reinforcing structure 2011 is too small. When the cover plate 2 is stamped, the material flow space of the rib 2022 and the reinforcing structure 2011 overlaps, stress is concentrated, and cracking is likely to occur. If g3 is greater than 30 mm, the distance between the rib 2022 and the reinforcing structure 2011 is too large, occupying too much space on the cover plate 2, and the arrangement space on the cover plate 2 is insufficient.

[0109] Therefore, by limiting g3 to a value between 3 mm and 30 mm, a reasonable distance is achieved between the reinforcing ring 202 and the reinforcing structure 2011. This avoids the overlap of material flow space during stamping, thus preventing stress concentration and cracking, ensuring the smooth forming of the cover plate 2. It also ensures that the cover plate 2 has sufficient arrangement space, improving the reliability of the cover plate 2.

[0110] Optionally, g3 can be any value among 3 mm, 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, and 30 mm, or a value between any two of these values.

[0111] In one embodiment, the vertical dimension of the overlapping ring 203 is h1, where h1 ranges from 0.5 mm to 10 mm. It should be noted that the vertical dimension of the overlapping ring 203 is its thickness. After the overlapping ring 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 3 As 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 ring 203 will not provide sufficient space for the weld pool in the vertical direction, resulting in an insufficient weld pool width and weak welding strength. This leads to poor connection stability between the cover plate 2 and the shell 1. Furthermore, an excessively small h1 will also result in insufficient structural strength of the overlap ring 203, which will also affect 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 ring 203 will be too large, wasting material and increasing weight, which is not conducive to improving the energy density of the battery cell. Here, the weld pool width refers to the width of the weld along the edge of the weld. Figure 3 The dimensions in the direction indicated by the middle arrow, which is "up" or "down".

[0112] Therefore, by limiting h1 to a value between 0.5 mm and 10 mm, the overlapping ring 203 has a reasonable thickness. This ensures that the overlapping ring 203 has sufficient structural strength and provides sufficient space for the welding pool during the welding of the shell and cover along the thickness direction, thereby ensuring welding strength, stability and reliability of the connection between the cover plate 2 and the shell 1 after welding, and also avoids material waste, which helps to reduce the weight of the cover plate 2 and facilitates the lightweighting of the battery cell.

[0113] 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.

[0114] In one embodiment, the distance between the lower surface of the rib 2022 and the lower surface of the overlapping ring 203 along the vertical direction is h2, where the value of h2 ranges from 0.4 mm to 10 mm. It should be noted that h2 is the dimension by which the rib 2022 protrudes downward relative to the overlapping ring 203, and also the dimension by which the rib 2022 extends into the inner cavity of the housing 1. During housing cover assembly, the rib 2022 extends into the housing 1 and is close to the inner side of the housing 1's sidewall, playing a certain positioning and fixing role. If h2 is less than 0.4 mm, the dimension of the rib 2022 along the thickness direction is too small, and the dimension extending into the housing 1 and fitting with the housing sidewall is insufficient. During housing cover assembly, the cover assembly is prone to popping out of the housing 1, which is inconvenient for production line assembly and housing cover welding. If h2 is greater than 10 mm, the dimension of the rib 2022 along the thickness direction is too large, making the rib 2022 difficult to stamp and form, wasting material, and resulting in excessive weight.

[0115] Therefore, by limiting h2 to a value between 0.4 mm and 10 mm, the rib 2022 protrudes downwards by a reasonable amount relative to the overlapping ring 203. This ensures a stable fit between the cover assembly and the housing 1 during the assembly of the cover, prevents the cover assembly from falling off the housing 1, facilitates assembly and welding on the production line, and improves assembly efficiency. It also ensures that the rib 2022 can be formed smoothly, avoids material waste, reduces weight, and saves costs.

[0116] 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.

[0117] 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, the housing 1 includes a side wall and a bottom wall, the bottom wall is disposed opposite to the open end, and the side wall is disposed circumferentially around 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 is provided with a set of cover plate assemblies, and the housing 1 is surrounded by the side walls.

[0118] In this embodiment, the battery cell features a recessed groove design around the cover plate 2, forming a reinforcing ring 202. This strengthens the structural strength of the cover plate 2, reduces the thickness of the cover plate body 201, and changes the assembly method between the cover plate 2 and the housing 1. While ensuring the welding strength of the housing and the strength of the cover plate, this improves the processing yield and structural reliability of the cover plate 2, as well as the assembly and welding yield of the housing and the cover, achieving lightweighting and reducing material costs.

[0119] It should be noted that the traditional method of fitting the casing 1 and the cover plate 2 of a square-shell battery cell is as follows: Figures 11 to 17As shown, the housing 1 has a first wall 111 and a second wall 112 arranged opposite each other along the length direction, and a third wall 113 and a fourth wall 114 arranged opposite each other along the width direction. The first wall 111 and the second wall 112 are the narrower side walls of the housing 1. The first wall 111 and the second wall 112 have stepped structures. After the cover plate 2 is inserted into the housing, the limiting surfaces 102 at the steps on both sides will hold the cover plate 2 in place, preventing it from falling into the housing. The wall thickness (step thickness) at the ends of the first wall 111 and the second wall 112... The portion above the structure has the same wall thickness as the third wall 113 and the fourth wall 114, while the wall thickness below the stepped structure is thicker, resulting in inconsistent thicknesses of the four side walls of the shell 1. In this embodiment, the overlapping ring 203 of the cover plate 2 directly overlaps with the first end face 101 of the opening end of the shell 1, eliminating the stepped structure on the first wall 111 and the second wall 112, and thinning the wall thickness below the original steps. This makes the wall thickness of all side walls of the shell 1 consistent, thereby reducing material usage and lowering the weight of the shell 1. The length direction refers to... Figure 12 and Figure 16 The middle arrow points to the "length direction"; the width direction refers to... Figure 14 and Figure 16 The middle arrow points to the "width direction"; the bottom arrow points to... Figure 12 and Figure 14 The direction indicated by the middle arrow is "down".

[0120] Alternatively, one can use, such as Figures 18 to 19 The cover plate 2 shown has its entire body 201 sunken down, with convex protrusions around it to form an overlapping ring 203. This can also achieve direct overlap between the cover plate 2 and the shell 1. However, compared with the structure of the reinforcing ring 202 formed by the groove 2021 and the rib 2022, the reinforcement effect is poor. After the cover plate body 201 sinks down, it occupies the internal space of the cell and reduces the cell capacity.

[0121] 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.

[0122] Table 1

[0123]

[0124] As can be seen from Table 1, for the battery cells of Examples 1 to 4, 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.

[0125] In Comparative Example 1, the w1 / h3 value is 0.28, which is less than 0.3 and outside the range of 0.3 to 0.8 defined in this application. During the stamping of the cover plate, the punch wears and cracks, leading to poor forming accuracy of the groove 2021 and a poor forming yield of the cover plate 2. In Comparative Example 2, the w1 / h3 value is 0.81, which is greater than 0.8 and outside the range defined in this application. Compared with the cover plate of the same thickness without a reinforcing ring, the strength is slightly worse. It can be seen that when w1 / h3 exceeds the range of 0.3 to 0.8 defined in this application, the forming yield of the cover plate 2 is poor or the structural strength of the cover plate 2 is insufficient. Therefore, when w1 / h3 is within the range of 0.3 to 0.8, the structural strength of the punch can be guaranteed, thereby ensuring the forming accuracy of the groove 2021 and ensuring the smooth forming of the groove 2021. At the same time, the groove 2021 can provide sufficient reinforcement to the structural strength of the cover plate 2.

[0126] For Comparative Example 3, the value of h4 / t is 5.1, which is greater than 5 and exceeds the upper limit of 1 < h4 / t ≤ 5, which is outside the range defined in this application. This results in the cover plate cracking during stamping, leading to a low production yield. Therefore, limiting h4 / t to the range of 1 < h4 / t ≤ 5 can prevent insufficient material flow space during stamping, thus avoiding cracking of the cover plate 2 and improving the processing yield.

[0127] For Comparative Example 4, the value of h2 is 0.38 mm, which is less than 0.4 mm, exceeding the lower limit and not within the range of 0.4 mm to 10 mm specified in this application. During shell and cover assembly, the cover plate is prone to popping out, which is not conducive to improving assembly efficiency. It can be seen that by limiting h2 to above 0.4 mm, the probability of the cover plate popping out during shell and cover assembly can be reduced, the relative stability between the cover plate and the shell can be improved, and assembly efficiency can be improved.

[0128] 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.

[0129] Optionally, the battery cell is a lithium-ion battery cell.

[0130] 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 battery cell, comprising: a shell having an open end, the end face of the open end being a first end face; a cover plate assembly arranged at the open end of the shell, the cover plate assembly comprising a cover plate, the cover plate comprising a cover plate body, a reinforcing ring portion and a lap ring portion, the reinforcing ring portion being connected around the outer circumferential side of the cover plate body, the upper surface of the reinforcing ring portion being configured with a groove, the lower surface of the reinforcing ring portion being configured with a convex rib corresponding to the groove, the convex rib extending into the inner cavity of the shell and being gap-fitted with the side wall of the shell, and the lap ring portion being connected around the outer circumferential side of the reinforcing ring portion and lapped on the first end face; the size of the bottom wall of the groove along the ring width direction of the reinforcing ring portion is w1, and the recess depth of the groove along the up-down direction is h3, wherein the relationship between w1 and h3 satisfies the relationship formula: 0.3<=w1 / h3<=0.8; the value range of w1 is: 0.6 mm<=w1<=30 mm; the value range of h3 is: 0.75 mm<=h3<=100 mm; the upper surface of the reinforcing ring portion is flush with the upper surface of the cover plate body, the distance between the upper surface and the lower surface of the reinforcing ring portion is h4, and the thickness dimension of the cover plate body along the up-down direction is t, wherein the relationship between h4, t and h3 satisfies the relationship formula: 0.3<= (h4-h3) / t<=1.5; the relationship between h4 and t satisfies the relationship formula: 1 the value range of h4 is: 0.5 mm the value range of t is: 0.5 mm<=t<=10 mm.

2. The electric cell of claim 1, wherein, The groove is at least part of a ring groove arranged circumferentially around the cover plate body, and the convex rib is at least part of a convex ring arranged circumferentially around the cover plate body.

3. The electric cell of claim 2, wherein, The upper surface of the lap ring portion is flush with the upper surface of the reinforcing ring portion, the distance between the edge of the side of the groove close to the lap ring portion and the outer circumferential edge of the lap ring portion on the plane where the upper surface of the lap ring portion is located is E, wherein the value range of E is: 2 mm<=E<=30 mm; And / or, the side wall of the side of the groove close to the cover plate body is a first side wall, and the included angle between the first side wall and the bottom wall is B, wherein the value range of B is: 92<=B<=150; And / or, the gap between the outer circumferential wall of the convex rib and the inner wall of the shell is g1, wherein the value range of g1 is: 0.03 mm<=g1<=0.3 mm.

4. The electric cell of claim 1, wherein, The battery cell further comprises a pole group and a connecting sheet arranged in the inner cavity of the shell, the connecting sheet being connected to the side of the pole group facing the cover plate, the distance between the convex rib and the connecting sheet along the up-down direction is g2, wherein the value range of g2 is: 2 mm<=g2<=10 mm; And / or, the cover plate body is configured with a reinforcing structure, and the distance between the convex rib and the reinforcing structure is g3, wherein the value range of g3 is: 3 mm<=g3<=30 mm.

5. The electric cell of any one of claims 1 to 4, wherein, The size of the lap ring portion along the up-down direction is h1, wherein the value range of h1 is: 0.5 mm<=h1<=10 mm; And / or, along the up-down direction, the distance between the lower surface of the convex rib and the lower surface of the lap joint ring part is h2, wherein the value range of h2 is: 0.4 mm≤h2≤10 mm.

6. A battery pack, characterized by, Comprising: a box; the electric core of any one of claims 1 to 5, which is arranged in the box.

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