Shell cover assembly structure, battery cell and battery pack

Abstract

The present application relates to the technical field of battery, and discloses a shell cover assembly structure, a battery cell and a battery pack.The shell cover assembly structure comprises a shell and a cover plate assembly.The shell comprises a side wall and a circular arc segment;in the assembly direction of the shell cover, the circular arc segment comprises a main body segment and a flared segment, and the flared segment extends to the open end of the shell;the outer wall surface of the flared segment is convex to the outer wall surface of the main body segment, the inner wall surface of the flared segment is concave to the inner wall surface of the main body segment, and the inner wall surface of the flared segment and the inner wall surface of the main body segment form a limiting structure;the cover plate assembly comprises a cover plate body, the cover plate body is assembled into the shell, the bottom surface of the cover plate body abuts against the limiting structure, and the top surface of the cover plate body is flush with the end surface of the open end of the shell;the inner fillet radius r1 of the main body segment, the inner fillet radius r2 of the flared segment and the radius r3 of the outer fillet side wall of the cover plate body satisfy a preset condition.The present application can improve the consistency of the shell cover assembly gap, simplify the structure of the cover plate body, reduce the processing difficulty and improve the welding yield of the shell cover.

Description

Technical Field

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

[0002] With the increasing maturity of lithium-ion battery technology, lithium-ion batteries are widely used as power batteries in electric vehicles and energy storage, and the requirements for the performance and safety of lithium-ion batteries are becoming increasingly stringent.

[0003] The battery cell consists of a cover plate assembly, a housing, and an electrode assembly. The cover plate assembly and the housing, after being welded together, form a sealed space with a certain mechanical strength to protect the electrode assembly.

[0004] Currently, the casing and cover plate of the battery cell are installed and welded with overlapping seams. That is, the cover plate is designed as a two-layer structure along its thickness direction, including a convex edge and a guide section. The convex edge presses against the casing opening, the guide section is inserted into the inside of the casing, and then the seams are welded together.

[0005] The complex structure of this cover plate makes it difficult to manufacture and carries a high risk of dimensional defects. This results in inconsistent gaps between the shell and the cover plate after assembly, leading to a low welding yield. Furthermore, at the rounded corners, the shell is currently formed by repeatedly bending sheet metal using a roll forming die and then welding it together with high-frequency welding. Due to the roll forming process, the radius of the inner rounded corners fluctuates significantly, while the outer rounded corners of the cover plate assembly are relatively consistent. Therefore, during assembly on the production line, the tightness of the fit between the shell and the cover plate assembly varies, making it easy for the cover plate assembly to damage the shell, resulting in high production line losses and a low shell-cover matching yield. Summary of the Invention

[0006] In view of this, the present invention provides a casing assembly structure, a battery cell, and a battery pack to solve the problem of low casing matching yield.

[0007] In a first aspect, the present invention provides a shell-and-cover assembly structure, including a shell and a cover plate assembly. The shell includes four side walls, which are connected end-to-end to form a hollow structure with open ends, and adjacent side walls are connected by arc segments. Along the assembly direction of the shell-and-cover, the arc segment includes a main body and flared sections at both ends of the main body, the flared sections extending to the open ends of the shell. The outer wall surface of the flared section protrudes beyond the outer wall surface of the main body, and the inner wall surface of the flared section is recessed within the inner wall surface of the main body, forming a limiting structure between the inner wall surface of the flared section and the inner wall surface of the main body. The cover plate assembly includes a cover plate body, the cover plate body having... The cover plate has straight sidewalls that mate with the four sidewalls of the shell, and outer rounded corner sidewalls that mate with the arc segments of the shell. Along the assembly direction of the cover, the cover plate body has a bottom surface and a top surface that are oppositely positioned. The cover plate body is assembled into the shell, with the bottom surface of the cover plate body abutting against the limiting structure, and the top surface of the cover plate body flush with the end face of the open end of the shell. The inner rounded corner radius of the main body section is r1 (mm), the inner rounded corner radius of the flared section is r2 (mm), and the radius of the outer rounded corner sidewall of the cover plate body is r3 (mm), satisfying the following:

[0008] r1 > r2,

[0009] r2=r3.

[0010] Beneficial effects: For the shell, a flared section is designed in the arc segment of the shell. The inner wall surface of the flared section is recessed into the inner wall surface of the main body segment. That is, along the plane section perpendicular to the length of the shell, the cavity cross-sectional area of ​​the shell at the flared section is larger than the cavity cross-sectional area of ​​the shell at the main body segment. The outer wall surface of the flared section protrudes outward from the outer wall surface of the main body segment, and the inner wall surface of the flared section is recessed into the inner wall surface of the main body segment. During the shell processing, an additional flaring process is added. Flaring is performed by fixing a precision flaring fixture, which opens and shapes the inner rounded corner of the shell's open end, making the inner wall surface of the flared section recessed into the inner wall surface of the main body segment. The radius of the inner rounded corner is reduced, that is, r1 > r2. Thus, the tolerance of the flared section of the shell is basically consistent with the assembly rounded corner tolerance of the cover plate assembly.

[0011] For the cover plate body, the protruding edge structure of the cover plate body is eliminated, so that the entire cover plate body is assembled into the interior of the housing. Ensure that the outer radius of the outer corner of the cover plate body is equal to the inner radius of the flared section of the housing, that is, r2=r3. This ensures that in the arc section, the cover and housing are not fitted too tightly, which would cause the cover plate assembly to damage the housing, reduce the assembly loss rate, and improve the matching yield of the cover and housing.

[0012] Because the structure of the cover plate body is simplified, the processing difficulty of the cover plate body is reduced, thereby reducing the risk of dimensional defects in the cover plate body. This results in high consistency of the gap between the shell and the cover plate after the straight sidewalls and outer rounded corner sidewalls are joined, thereby further improving the welding yield of the shell and the cover plate.

[0013] In one alternative implementation, the following condition is also met:

[0014] 0.1mm≤r1 r2≤0.15mm,

[0015] 0.9mm≤r2≤2.5mm.

[0016] In one optional embodiment, along the assembly direction of the cover, the extension length of the flared section is h1 (in mm), and the cover body includes an assembly section that mates with the flared section of the housing. The thickness of the assembly section is h2 (in mm), satisfying the following:

[0017] h1=h2.

[0018] In one optional embodiment, along the assembly direction of the cover, the cover body further includes a chamfered section. The total thickness of the cover body is h (in mm), and the thickness of the chamfered section is h3 (in mm), satisfying the following:

[0019] h2 = h - h3.

[0020] In one optional embodiment, the length of the flared section along the assembly direction of the shell cover is h1, in mm, and satisfies:

[0021] 2.5mm≤h1≤5mm.

[0022] In one optional embodiment, the limiting structure includes a connecting segment, one end of which is connected to the main body segment, and the other end of which is connected to the flared segment. The connecting segment is an arc-shaped surface inclined relative to the main body segment. Along the assembly direction of the shell cover, the length of the connecting segment is h4 mm, satisfying the following:

[0023] 0.5mm≤h4≤2mm.

[0024] In one optional implementation, along the circumference of the arc segment, at the center of the arc, the wall thickness of the main body segment is t1 (in mm), and the wall thickness of the flared segment is t2 (in mm), satisfying the following:

[0025] t2≤t1.

[0026] In one alternative implementation, the following condition is also met:

[0027] 0.3mm≤t1≤1.2mm,

[0028] 0.25mm≤t2≤1.15mm.

[0029] Secondly, the present invention also provides a battery cell, including an electrode assembly and the casing and cover assembly structure described in the above technical solutions. The casing and cover assembly form a sealed accommodating cavity; the electrode assembly is disposed within the accommodating cavity.

[0030] Beneficial effects: Since the battery cell includes the casing assembly structure, it has the same technical effects as the casing assembly structure, which will not be elaborated here.

[0031] Thirdly, the present invention also provides a battery pack comprising multiple battery cells from more than one technical solution, wherein the battery cells are electrically connected to each other.

[0032] Beneficial effects: Since the battery pack includes the cells, it has all the technical benefits of the cells, which will not be elaborated here. Attached Figure Description

[0033] 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.

[0034] Figure 1 This is an exploded view of a battery cell in the relevant technology;

[0035] Figure 2 for Figure 1 The diagram shows the structure of the cover plate assembly in the battery cell.

[0036] Figure 3 for Figure 2 The front view of the cover plate assembly shown;

[0037] Figure 4 for Figure 1 The image shown is a partial enlarged view of the battery cell after assembly.

[0038] Figure 5 For along Figure 4 Sectional view at point MM;

[0039] Figure 6 for Figure 5 A magnified view of a portion of point N in the middle;

[0040] Figure 7 This is a schematic diagram of the shell structure in a shell cover assembly structure according to an embodiment of the present invention;

[0041] Figure 8 for Figure 7 A magnified view of a section at point A in the middle;

[0042] Figure 9 for Figure 7 The left view of the casing shown;

[0043] Figure 10 For along Figure 9 Sectional view at point BB;

[0044] Figure 11 for Figure 10 A magnified view of a section at point D;

[0045] Figure 12 for Figure 9 A magnified view of a section at point C;

[0046] Figure 13 for Figure 7 The front view of the casing shown;

[0047] Figure 14 for Figure 13 A magnified view of a section at point E in the middle;

[0048] Figure 15 For along Figure 13 Sectional view at FF;

[0049] Figure 16 for Figure 15 A magnified view of a section at point G in the middle;

[0050] Figure 17 This is a schematic diagram of the cover plate assembly in a shell and cover assembly structure according to an embodiment of the present invention;

[0051] Figure 18 for Figure 17 The front view of the cover plate assembly shown;

[0052] Figure 19 for Figure 18 A magnified view of a section at point I;

[0053] Figure 20 for Figure 17 Top view of the cover plate assembly shown;

[0054] Figure 21 for Figure 20 A magnified view of a section at point J;

[0055] Figure 22 This is a partially enlarged view of a battery cell according to an embodiment of the present invention;

[0056] Figure 23 For along Figure 22 Sectional view at point KK;

[0057] Figure 24 for Figure 23 A magnified view of the area at point L.

[0058] Figures 1 to 6 Explanation of reference numerals in the attached diagram:

[0059] 1', Housing; 2', Cover assembly; 201', Cover body; 2011', Protruding edge; 2012', Guide section; 100', Battery cell.

[0060] Figures 7 to 24 Explanation of reference numerals in the attached diagram:

[0061] 1. Shell; 101. Side wall; 102. Arc segment; 1021. Main body segment; 1022. Flared segment; 1023. Connecting segment; 2. Cover plate assembly; 201. Cover plate body; 2011. Straight edge side wall; 2012. Outer rounded corner side wall; 2013. Bottom surface; 2014. Top surface; 2015. Assembly segment; 2016. Chamfered segment; 3. Electrode group; 4. End plate; 5. Side plate; 6. Bare cell insulation sheet; 100. Cell. Detailed Implementation

[0062] 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.

[0063] In the relevant technology of cell 100', its housing 1' and cover plate assembly 2' are installed and welded together by lap joint.

[0064] Specifically, Figures 1 to 6 The diagram illustrates the structure of a battery cell 100' and its housing 1' and cover assembly 2' in the related art. The cover assembly 2' includes a cover body 201', which has a two-step structure along its thickness direction. (Refer to...) Figures 2 to 6 It includes a protruding edge 2011' and a guide section 2012'. During assembly, the protruding edge 2011' of the cover plate body 201' presses against the opening of the housing 1', the guide section 2012' of the cover plate body 201' is inserted into the interior of the housing 1', and then the seams are welded.

[0065] Due to the complex structure and high processing difficulty of the cover plate body 201', the risk of dimensional defects is high, resulting in inconsistent gaps between the shell 1' and the cover plate body 201' after seam fitting, affecting the welding yield of the shell 1' and the cover plate body 201'. Furthermore, the shell 1' is currently formed by repeatedly bending sheet metal through a roll forming die and then welding it together using high-frequency welding. Due to the roll forming process, the radius of the inner rounded corners fluctuates significantly, with a tolerance of ±0.1mm, while the consistency of the outer rounded corners of the cover plate body 201' is relatively good, with a tolerance of ±0.03mm. During production line assembly, the tightness of the fit between the shell 1' and the cover plate assembly 2' is inconsistent, making the cover plate assembly 2' prone to damaging the shell 1', resulting in high production line losses and a low shell-cover matching yield.

[0066] In addition, the stepped structure of the cover plate body 201' is relatively complex, which increases the difficulty of processing and the risk of dimensional defects.

[0067] Therefore, the present invention improves the assembly structure between the housing 1' and the cover plate body 201' to solve the above-mentioned technical problems.

[0068] The following is combined Figures 7 to 24 The following describes embodiments of the present invention.

[0069] According to an embodiment of the present invention, in a first aspect, a shell-and-cover assembly structure is provided, including a shell 1 and a cover assembly 2. The shell 1 includes four sidewalls 101, which are connected end-to-end to form a hollow structure with open ends. Adjacent sidewalls 101 are connected by arc segments 102. Along the assembly direction of the shell-and-cover, the arc segment 102 includes a main body segment 1021 and flared segments 1022 located at both ends of the main body segment 1021, extending to the open ends of the shell 1. The outer wall surface of the flared segment 1022 protrudes beyond the outer wall surface of the main body segment 1021, and the inner wall surface of the flared segment 1022 is recessed within the inner wall surface of the main body segment 1021, forming a limiting structure between the inner wall surface of the flared segment 1022 and the inner wall surface of the main body segment 1021. The cover assembly 2 includes a cover body 201, which has... The cover has straight sidewalls 2011 that mate with the four sidewalls 101 of the shell 1, and outer rounded corner sidewalls 2012 that mate with the arc segment 102 of the shell 1. Along the assembly direction of the cover, the cover body 201 has a bottom surface 2013 and a top surface 2014 that are oppositely arranged. The cover body 201 is assembled into the shell 1, with the bottom surface 2013 of the cover body 201 abutting against the limiting structure, and the top surface 2014 of the cover body 201 flush with the end face of the open end of the shell 1. The inner rounded corner radius of the main body segment 1021 is r1 (mm), the inner rounded corner radius of the flared segment 1022 is r2 (mm), and the radius of the outer rounded corner sidewall 2012 of the cover body 201 is r3 (mm), satisfying the following:

[0070] r1 > r2,

[0071] r2=r3.

[0072] Specifically, the housing 1 has four sidewalls 101. Taking a blade battery cell as an example, the housing 1 includes a first sidewall and a second sidewall arranged opposite to each other, and a third sidewall and a fourth sidewall connecting the first sidewall and the second sidewall. The areas of the first sidewall and the second sidewall are significantly larger than the areas of the third sidewall and the fourth sidewall. The first sidewall and the second sidewall are also referred to as the large surfaces of the housing 1, while the third sidewall and the fourth sidewall are also referred to as the narrow sides of the housing 1. The housing 1, enclosed by the four sidewalls 101, has an internal cavity for accommodating the electrode assembly 3.

[0073] The housing 1 has open ends, which are used to assemble with two cover plate assemblies 2. After the cover plate assemblies 2 and the housing 1 are assembled, a sealed space is formed to protect the electrode group 3 and contain the electrolyte.

[0074] Because the flatness of the open end of the shell 1 is difficult to control, the gap between the shell 1 and the cover plate after assembly is inconsistent, affecting the welding yield of the shell 1 and the cover plate. Furthermore, due to the forming process of the shell 1, the tolerance of the inner radius of the arc segment 102 of the shell 1 is large, while the tolerance of the corresponding assembly radius of the cover plate assembly 2 is small. Therefore, during the assembly process, the tightness of the fit between the shell 1 and the cover plate assembly 2 in the arc segment 102 may be inconsistent. When the fit is too tight, the cover plate assembly 2 is prone to damaging the shell 1, resulting in high production line losses and low shell-cover matching yield.

[0075] Therefore, the present invention optimizes and improves the structure of the housing 1 and the cover plate body 201.

[0076] For the shell 1, a flared section 1022 is designed in the arc segment 102 of the shell 1. The inner wall surface of the flared section 1022 is recessed into the inner wall surface of the main body segment 1021. That is, along the plane section perpendicular to the length direction of the shell 1, the cavity cross-sectional area of ​​the shell 1 at the flared section 1022 is greater than the cavity cross-sectional area of ​​the shell 1 at the main body segment 1021.

[0077] The outer wall of the flared section 1022 protrudes beyond the outer wall of the main body section 1021, while the inner wall of the flared section 1022 is recessed within the inner wall of the main body section 1021. During the processing of the shell 1, a flaring process is added. The flaring is performed by fixing a precision flaring fixture, which opens and shapes the inner rounded corner of the open end of the shell 1, so that the inner wall of the flared section 1022 is recessed within the inner wall of the main body section 1021. The radius of the inner rounded corner is reduced, i.e., r1 > r2. As a result, the tolerance of the flared section 1022 of the shell 1 is basically consistent with the assembly rounded corner tolerance of the cover plate assembly 2.

[0078] For the cover plate body 201, the protruding edge structure of the cover plate body 201 is eliminated, so that the cover plate body 201 is fully assembled into the interior of the housing 1. The outer radius of the outer corner of the cover plate body 201 is ensured to be equal to the inner radius of the flared section 1022 of the housing 1, i.e., r2=r3. This ensures that in the arc section 102, the cover and housing assembly 2 are not too tightly fitted, which could damage the housing 1, reducing assembly loss and improving the cover and housing matching yield.

[0079] Because the structure of the cover plate body 201 is simplified, the processing difficulty of the cover plate body 201 is reduced, thereby reducing the risk of dimensional defects in the cover plate body 201. This results in high consistency of the gap between the shell 1 and the cover plate after they are joined, thereby further improving the welding yield of the shell 1 and the cover plate.

[0080] Along the assembly direction, the cover plate body 201 is assembled into the interior of the housing 1. The bottom surface 2013 of the cover plate body 201 is limited by the limiting structure of the inner wall of the housing 1, which can prevent the cover plate body 201 from falling into the housing 1. At the same time, the top surface 2014 of the cover plate body 201 is flush with the end face of the open end of the housing 1. Finally, the housing 1 and the cover plate body 201 are welded together, and the two are fused and fixed together.

[0081] Specifically, the assembly direction is the length direction of the housing 1, and is consistent with the thickness direction of the cover plate body 201.

[0082] In some embodiments, the following condition is also satisfied: 0.1mm ≤ r1 r2≤0.15mm, 0.9mm≤r2≤2.5mm.

[0083] In the above embodiments, it has been explained that by setting the flared section 1022, the inner radius of the flared section 1022 is smaller than the inner radius of the main body section 1021, which can reduce the tolerance of the housing 1 in the flared section 1022, thereby better matching the assembly section 2015 of the cover assembly 2. In order to further improve the housing-cover fit yield and improve the product consistency of the battery cell, in this embodiment, the difference between the inner radius r1 of the main body section 1021 and the inner radius r2 of the flared section 1022 is further limited to the range of 0.1mm to 0.15mm.

[0084] r1 r2 ≥ 0.1mm, meaning the inner corner radius r2 of the flared section 1022 is at least 0.1mm smaller than the inner corner radius r1 of the main body section 1021. This completely covers the ±0.1mm tolerance fluctuation of the roll forming process of the housing 1. Compared to the inner corner radius r2 + 0.1mm when the housing 1 does not have the flared section 1022, this avoids the problem of excessively tight assembly when the cover plate assembly 2 is pressed in. If r1 If r2 is too small, below 0.1mm, the flaring and shaping will not be obvious, and the tolerance of the inner radius of the shell 1 will still fluctuate greatly, affecting the assembly yield of the shell cover.

[0085] r1 r2≤0.15mm, that is, the inner radius r2 of the flared section 1022 is at most 0.15mm larger than the inner radius r1 of the main body section 1021. Otherwise, flaring will be difficult and may cause some material of the flared section 1022 of the shell 1 to crack, increasing the wear of the shell 1.

[0086] If the above condition 0.1mm≤r1 is met... Under the condition that r2≤0.15mm, the range of the inner fillet radius r2 of the flared section 1022 is further limited to be within the range of 0.9mm to 2.5mm.

[0087] If r2 is too small, below 0.9mm, the flaring will be too large. In the flaring process, this will not only increase the difficulty of flaring, but also easily cause the material of the flared section 1022 of the shell 1 to crack, increasing the wear of the shell 1.

[0088] r2 is too large, exceeding 2.5mm, the flaring and shaping are not obvious, and the inner fillet tolerance of shell 1 still fluctuates greatly, affecting the assembly yield of the shell cover.

[0089] In some embodiments, the inner fillet radius r2 of the flared section 1022 includes 0.9mm, 1.0mm, 1.2mm, 1.5mm, 1.8mm, 2.0mm, 2.2mm, and 2.5mm.

[0090] The value of the inner fillet radius r2 of the flared section 1022 and the difference between it and the inner fillet radius r1 of the main body section 1021 satisfy 0.1mm≤r1 If r2≤0.15mm, the value of the inner fillet radius r1 of the main body segment 1021 can be determined.

[0091] In some embodiments, along the assembly direction of the cover, the extension length of the flared section 1022 is h1, in mm, and the cover body 201 includes an assembly section 2015 that mates with the flared section 1022 of the housing 1. The thickness of the assembly section 2015 is h2, in mm, satisfying: h1=h2.

[0092] Specifically, refer to Figure 14 and Figure 19 The extension length of the flared section 1022 is equal to the thickness of the assembly section 2015, h1=h2, which ensures a tight fit between the cover and the housing 1 in the assembly direction, reduces assembly gaps, and improves assembly accuracy and overall structural stability. Simultaneously, the assembly section 2015 of the cover body 201 can be completely embedded into the flared section 1022 of the housing 1, ensuring that the bottom surface 2013 of the cover body 201 is precisely abutted and limited by the limiting structure, and the top surface 2014 of the cover body 201 is flush with the open end face of the housing 1, thereby improving the welding yield between the housing 1 and the cover.

[0093] In some embodiments, along the assembly direction of the cover, the cover body 201 further includes a chamfered section 2016, the total thickness of the cover body 201 is h in mm, the thickness of the chamfered section 2016 is h3 in mm, and the following condition is met: h2 = h - h3.

[0094] In this embodiment, a chamfered section 2016 is also provided in the thickness direction of the cover plate body 201. The thickness h2 of the assembly section 2015 is the total thickness of the cover plate body 201 minus the thickness of the chamfered section 2016. The chamfered section 2016 on the cover plate body 201 can guide the cover plate body 201 to smoothly enter the flared section 1022 of the housing 1, avoiding jamming or misalignment caused by inaccurate edge alignment during assembly, thereby improving assembly efficiency and manufacturability.

[0095] The chamfer design can also effectively compensate for minor errors in the assembly process, reduce assembly defects caused by dimensional errors, and thus improve the compatibility and fault tolerance between the cover and the housing 1.

[0096] The introduction of the chamfered section 2016 can also reduce the edge stress concentration phenomenon in the contact area between the assembly section 2015 and the flared section 1022, improve the fatigue resistance of the structure, and extend the service life of the product.

[0097] In some embodiments, along the assembly direction of the cover, the length of the flared section 1022 is h1, in mm, satisfying: 2.5mm≤h1≤5mm.

[0098] In this embodiment, the length of the flared section 1022 is limited to the range of 2.5mm to 5mm.

[0099] h1 ≥ 2.5 mm, ensuring that the length of the flared section 1022 can cover the assembly length between the housing 1 and the cover assembly 2, thereby improving the assembly yield of the housing cover. If h1 < 2.5 mm, the mating section between the cover assembly 2 and the housing 1 may not be able to be inserted into the housing 1, or the housing 1 may still be damaged.

[0100] h1 ≤ 5mm, to avoid excessive flaring stroke of the flaring fixture during the flaring process, which could cause scratches on the housing 1 and increase wear. Simultaneously, to avoid an excessively long flaring section 1022 resulting in an ineffective flaring section 1022, which would increase the space occupied by the housing 1 and affect the energy density of the battery pack. While ensuring a good match between the housing 1 and the cover assembly 2, the length h1 of the flaring section 1022 should be as short as possible to ensure that the structural strength of the housing 1 itself is not affected.

[0101] In some embodiments, the limiting structure includes a connecting segment 1023, one end of which is connected to the main body segment 1021, and the other end of which is connected to the flared segment 1022. The connecting segment 1023 is an arc-shaped surface inclined relative to the main body segment 1021. Along the assembly direction of the shell cover, the length of the connecting segment 1023 is h4 in mm, which satisfies the condition: 0.5mm≤h4≤2mm.

[0102] Specifically, the flared section 1022 and the main body section 1021 are connected by a connecting section 1023, which is a frustum with the same sector angle as the main body section 1021.

[0103] Specifically, since both the flared section 1022 and the main body section 1021 are arc sections 102, the connecting section 1023 is a partial side surface of a frustum. One end of the connecting section 1023 connects to the flared section 1022, and the other end connects to the main body section 1021. Since the outer wall surface of the flared section 1022 protrudes from the outer wall surface of the main body section 1021, setting the connecting section 1023 as a slope allows for a smooth transition between the flared section 1022 and the main body section 1021, which can alleviate the stress concentration problem between the flared section 1022 and the main body section 1021, and improve the overall structural strength and durability of the battery cell casing 1.

[0104] For the housing 1, compared to the sidewall 101, the arc segment 102 is usually a structurally weak area. Therefore, the structural strength of the arc segment 102 needs to be considered. In this embodiment, the length of the connecting segment 1023 is controlled within the range of 0.5mm to 2mm, which can effectively disperse the stress at the connection between the flared segment 1022 and the main body segment 1021, avoid structural fatigue or cracking caused by local stress concentration, and improve the durability of the battery cell housing 1.

[0105] In some embodiments, along the circumference of the arc segment 102, at the center of the arc, the wall thickness of the main body segment 1021 is t1 (in mm), and the wall thickness of the flared segment 1022 is t2 (in mm), satisfying: t2≤t1.

[0106] Since the main body segment 1021 is formed by bending sheet metal, it has a uniform wall thickness. Along the circumference of the arc segment 102, the two ends of the inner arc of the main body segment 1021 are tangent to the two adjacent side walls 101. The wall thickness of the main body segment 1021 is the same as the wall thickness of the side walls 101, thus ensuring that the arc segment 102 of the housing 1 has sufficient structural strength to withstand the internal pressure of the battery cell before the explosion-proof valve bursts.

[0107] The wall thickness of the flared section 1022 is less than that of the main body section 1021. The thinner wall thickness of the flared section 1022 can better adapt to the assembly and welding of the cover plate assembly 2. At the same time, it can reduce the flaring processing resistance and improve the forming consistency of the flared section 1022.

[0108] In some embodiments, the following conditions are also met: 0.3mm≤t1≤1.2mm, 0.25mm≤t2≤1.15mm.

[0109] The main body segment 1021 serves as the main load-bearing part of the arc segment 102 of the cell casing 1. Its wall thickness t1 is controlled within the range of 0.3mm to 1.2mm. This ensures sufficient structural strength while preventing the casing 1 from becoming too heavy, thereby reducing weight and cost and improving the overall energy density of the battery.

[0110] The wall thickness t2 of the flared section 1022 is controlled within the range of 0.25mm to 1.15mm to ensure that it is as thin as possible while meeting the requirements of good assembly with the cover plate assembly 2, thereby further achieving the weight reduction of the housing 1.

[0111] The wall thickness t2 of the flared section 1022 must not be less than 0.25mm, otherwise the structural strength of the flared section 1022 of the housing 1 will be insufficient, affecting the assembly and welding quality with the cover plate assembly 2.

[0112] According to an embodiment of the present invention, in a second aspect, a battery cell 100 is also provided, including an electrode assembly 3 and the housing and cover assembly structure described in the above embodiments. The housing 1 and the cover assembly 2 form a sealed accommodating cavity; the electrode assembly 3 is disposed within the accommodating cavity.

[0113] Because the battery cell 100 includes the shell and cover assembly structure in the above embodiments, it can improve the assembly yield of the shell 1 and cover plate assembly 2 in the battery cell 100, reduce assembly losses, thereby improving the consistency of the battery cell 100 and reducing the manufacturing cost of the battery cell 100. Since the battery cell 100 includes the shell and cover assembly structure, it has all the technical effects of the shell and cover assembly structure; other effects will not be elaborated here.

[0114] In some embodiments, both ends of the housing 1 are open, respectively for mounting the cover plate assembly 2 for the positive electrode and the cover plate assembly 2 for the negative electrode. The electrode assembly 3 has positive electrode tabs and negative electrode tabs at both ends along its length. After the electrode assembly 3 is assembled into the housing, the positive electrode tabs and negative electrode tabs are located at the two open ends of the housing 1.

[0115] The cover plate assembly 2 at the positive end has a positive terminal post, which is electrically connected to the positive terminal tab. The cover plate assembly 2 at the negative end has a negative terminal post, which is electrically connected to the negative terminal tab.

[0116] The cover plate assembly 2 also includes a cover plate body 201, a riveting block, an upper insulating component, a lower insulating component, and a sealing ring.

[0117] The battery cell 100 further includes an end plate 4, a side plate 5, and a bare battery cell insulating sheet 6. The end plate 4 is located between the cover plate assembly 2 of the positive electrode and the electrode group 3, and is used to press the electrode group 3 to prevent the electrode group 3 from being impacted or shaken, and to house and limit the positive electrode tab to prevent the tab from being deviated or divergent. After the side plate 5 and the bare battery cell insulating sheet 6 are welded and fixed, they are wrapped around the outside of the electrode group 3. In addition, along the length direction of the housing 1, one end of the bare battery cell insulating sheet 6 extends to be melt-fixed to the lower insulating member of the negative electrode cover plate assembly 2, and the other end extends to the positive electrode end and is melt-fixed to the end plate 4, so that the electrode group 3 is better fixed in the housing 1 and the electrode group 3 is prevented from being short-circuited.

[0118] In some embodiments, the battery cell 100 includes a blade battery cell.

[0119] According to an embodiment of the present invention, in a third aspect, a battery pack is further provided, which includes a plurality of battery cells 100 in the above embodiments, and the battery cells 100 are electrically connected to each other.

[0120] Since the battery pack includes the battery cell 100 and has all the technical effects of the battery cell 100, they will not be elaborated here.

[0121] In order to verify the technical effects of the present invention, three specific experimental cases are provided below.

[0122] Prepare different housing samples, and measure the wall thickness t2 at the center of the arc of the flared section 1022 of the housing with different bending radii r1 after flaring.

[0123] Assemble each housing sample with the corresponding cover plate assembly, and detect the assembly yield of the housing cover and the pressure resistance of the battery cell housing.

[0124] Detection of the assembly yield of the housing cover: Check the assembly gap of the housing cover and whether the housing is damaged by pressing. The assembly gap less than 0.15 mm is qualified, and the assembly yield ≥ 99.5% is qualified.

[0125] Detection of pressure resistance: Apply a gradually increasing pressure to the battery cell, the charging pressure is 1.7 Mpa, the charging time is 30 s, and the pressure increasing rate is 0.07 Mpa / s until the battery cell bursts, and record the burst pressure value as P. P ≥ 1.2 Mpa is qualified.

[0126] The first group: The wall thickness of the main body section 1021 of the housing before flaring is t1 = 0.35 mm. After flaring with the same flaring tooling, r2 = 1.5 mm.

[0127] The measured results are shown in Table 1.

[0128] Table 1

[0129]

[0130] It can be seen from Table 1 that:

[0131] In Implementation Cases 1 to 3, r1 The value of r2 is less than 0.1mm. Although the withstand voltage test result is qualified, after the shell and cover are assembled, there are shell damage and excessive mating clearance. As a result, the fit rate of the shell and cover is less than 99.5%, which does not meet the requirements for cell use.

[0132] In Implementation Cases 10 to 12, r1 The value of r2 is greater than 0.15mm. Although the fit of the shell and cover is qualified, the flare is too large and the inner round corner of the flare section is severely stretched, which affects the pressure resistance of the shell and causes the cell to fail the pressure resistance test and not meet the requirements for cell use.

[0133] In Implementation Cases 4 through Implementation Cases 9, r1 The value of r2 is within the range of 0.1mm to 0.15mm, the fit of the casing is qualified, the cell withstand voltage test is qualified, and the cell usage requirements are met.

[0134] Group 2: The wall thickness of the main body section 1021 of the shell before flaring is t1=0.4mm. After flaring with the same flaring tool, r2=1.5mm.

[0135] The measured results are detailed in Table 2.

[0136] Table 2

[0137]

[0138] Table 2 shows that:

[0139] In Implementation Cases 13 to 15, r1 The value of r2 is less than 0.1mm. Although the withstand voltage test result is qualified, after the shell and cover are assembled, there are shell damage and excessive mating clearance. As a result, the fit rate of the shell and cover is less than 99.5%, which does not meet the requirements for cell use.

[0140] In Implementation Cases 22 to 24, r1 The value of r2 is greater than 0.15mm. Although the fit of the shell and cover is qualified, the flare is too large and the inner round corner of the flare section is severely stretched, which affects the pressure resistance of the shell and causes the cell to fail the pressure resistance test and not meet the requirements for cell use.

[0141] In Implementation Cases 16 to 21, r1 The value of r2 is within the range of 0.1mm to 0.15mm, the fit of the casing is qualified, the cell withstand voltage test is qualified, and the cell meets the usage requirements.

[0142] Group 3: The wall thickness of the main body section 1021 of the shell before flaring is t1=0.5mm. After flaring with the same flaring tool, r2=2mm.

[0143] The actual measurement results are detailed in Table 3.

[0144] Table 3

[0145]

[0146] Table 3 shows that:

[0147] In Implementation Cases 25 to 27, r1 The value of r2 is less than 0.1mm. Although the withstand voltage test result is qualified, after the shell and cover are assembled, there are shell damage and excessive mating clearance. As a result, the fit rate of the shell and cover is less than 99.5%, which does not meet the requirements for cell use.

[0148] In Implementation Cases 34 to 36, r1 The value of r2 is greater than 0.15mm. Although the fit of the shell and cover is qualified, the flare is too large and the inner round corner of the flare section is severely stretched, which affects the pressure resistance of the shell and causes the cell to fail the pressure resistance test and not meet the requirements for cell use.

[0149] In Implementation Cases 28 to 33, r1 The value of r2 is within the range of 0.1mm to 0.15mm, the fit of the casing is qualified, the cell withstand voltage test is qualified, and the cell usage requirements are met.

[0150] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A shell cover assembly structure characterized by comprising: The shell cover assembly structure comprises: a shell comprising four side walls, the four side walls being connected end to end to form a hollow structure with an open end, and each of the adjacent side walls being connected by an arc segment; in the assembly direction of the shell cover, the arc segment comprises a main body segment and flared segments arranged at both ends of the main body segment, the flared segments extending to the open end of the shell, the outer wall surface of the flared segment being convex relative to the outer wall surface of the main body segment, the inner wall surface of the flared segment being concave relative to the inner wall surface of the main body segment, and a limiting structure being formed between the inner wall surface of the flared segment and the inner wall surface of the main body segment; a cover plate assembly comprising a cover plate body, the cover plate body having straight side walls matched with the four side walls of the shell and rounded side walls matched with the arc segments of the shell, and the cover plate body having a bottom surface and a top surface arranged oppositely in the assembly direction of the shell cover, the cover plate body being assembled into the shell, the bottom surface of the cover plate body being in abutment with the limiting structure, and the top surface of the cover plate body being flush with the end surface of the open end of the shell; the inner radius of the rounded corner of the main body segment is r1, unit: mm, the inner radius of the rounded corner of the flared segment is r2, unit: mm, the radius of the rounded side wall of the cover plate body is r3, unit: mm, satisfying: r1＞r2， r2=r3； the shell cover assembly structure further satisfies: 0.1mm≤r1-r2≤0.15mm, 0.9mm≤r2≤2.5mm; the limiting structure comprises a connecting segment, one end of the connecting segment being connected with the main body segment and the other end of the connecting segment being connected with the flared segment, and the connecting segment being an arc surface inclined relative to the main body segment; in the assembly direction of the shell cover, the extension length of the flared segment is h1, unit: mm, the cover plate body comprises an assembly segment matched with the flared segment of the shell, and the thickness of the assembly segment is h2, unit: mm, satisfying: h1=h2; in the assembly direction of the shell cover, the cover plate body further comprises a chamfer segment, the total thickness of the cover plate body is h, unit: mm, and the thickness of the chamfer segment is h3, unit: mm, satisfying: h2=h-h3; the shell cover assembly structure further satisfies: 2.5mm≤h1≤5mm; in the assembly direction of the shell cover, the length of the connecting segment is h4, unit: mm, satisfying: 0.5mm≤h4≤2mm.

2. The shell cover assembly structure according to claim 1, wherein in the circumferential direction of the arc segment, at the center of the arc, the wall thickness of the main body segment is t1, unit: mm, and the wall thickness of the flared segment is t2, unit: mm, satisfying: t2≤t1.

3. The shell cover assembly structure according to claim 2, wherein further satisfying: 0.3mm≤t1≤1.2mm, 0.25mm≤t2≤1.15mm.

4. An electric cell characterized by The shell cover assembly structure comprises: any one of claims 1 to 3, the shell and the cover plate assembly forming a sealed accommodation cavity; a pole group arranged in the accommodation cavity.

5. A battery pack, characterized by, a plurality of the battery cell of claim 4, each of the battery cells being electrically connected.

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