Cell Core Housing and Cover Plate Matching Structure and Cell Core

Abstract

The present invention provides a matching structure between a battery cell housing and a cover plate, and a battery cell. The matching structure between the battery cell housing and the cover plate of the present invention includes an opening formed on the battery cell housing; a boss is provided on the cover plate, and a lapping portion is formed at the root of the boss; the boss extends into the battery cell housing from the opening, the lapping portion laps on the battery cell housing, the boss and the opening are in a near-zero fit, the outer end face of the lapping portion is flush with the outer side face of the battery cell housing, and the cover plate and the battery cell housing are connected by welding; the ratio K1 of the thickness L2 of the lapping portion to the thickness L1 of the cover plate satisfies: 16.7% ≤ K1 ≤ 80%, the ratio K2 of the thickness Ln of the boss to the thickness L1 of the cover plate satisfies: 20% ≤ K2 ≤ 83.3%, and it satisfies: K1 + K2 = 1. The matching structure between the battery cell housing and the cover plate of the present invention can improve the matching degree between the battery cell housing and the cover plate, and can improve the welding strength and the welding yield rate between the battery cell housing and the cover plate, and ensure the sealing performance after welding.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium batteries, and particularly to a cooperation structure between a cell housing and a cover plate. The present invention also relates to a cell provided with the above-mentioned cooperation structure between the cell housing and the cover plate. Background Art

[0002] Lithium-ion power batteries generally include an internal battery structure and an external battery structure. The internal battery structure mainly includes a cell electrode group, and the external battery structure mainly includes a cell cover plate and a cell housing. The cell housing provides a receiving space for the cell electrode group, and the cell cover plate and the cell housing are cooperatively welded to form a closed space, thereby forming a complete lithium-ion battery structure.

[0003] Among them, in a blade lithium-ion battery, the cell housing is usually formed by high-frequency welding and laser welding processes, and both sides of the housing are open structures, which are convenient for welding cooperation with the cell cover plate. In the prior art, the cell electrode group is first installed inside the cell housing, and then the open opening is blocked by the cell cover plate, and laser seam welding is used to weld it at the opening to seal the cell cover plate and the cell housing.

[0004] However, since the above-mentioned seal welding method does not restrict the cooperation dimensions and structure between the cell housing and the cover plate, the welded connection between the cell cover plate and the cell housing is not firm enough, the welding yield is low, and the welding seam between the cell cover plate and the cell housing is prone to cracking and damage, increasing production costs and reducing production efficiency; especially when gas is generated during the charging and discharging process of the battery, the internal air pressure will form a shear force at the welding seam, and the weld is prone to cracking, and its poor sealing performance causes the battery to leak liquid, resulting in battery failure, and even serious safety accidents may occur. Summary of the Invention

[0005] In view of this, the present invention aims to provide a cooperation structure between a cell housing and a cover plate, so as to improve the welding strength and welding yield between the cell housing and the cover plate.

[0006] To achieve the above object, the technical solution of the present invention is realized as follows:

[0007] A cooperation structure between a cell housing and a cover plate includes an open opening formed on the cell housing;

[0008] The cover plate is provided with a convex platform protruding toward the cell housing side, and a lapping portion is formed at the root of the convex platform; the convex platform extends into the cell housing from the open opening, the lapping portion laps on the cell housing, the length and width of the convex platform are respectively set corresponding to the length and width of the open opening, the outer end surface of the lapping portion is flush with the outer side surface of the cell housing, and the cover plate is welded to the cell housing;

[0009] In the assembled state of the cover plate and the battery cell housing, the ratio K1 of the thickness L2 of the overlapping portion to the thickness L1 of the cover plate satisfies: K1 = L2 / L1, 16.7% ≤ K1 ≤ 80%. The ratio K2 of the thickness Ln of the boss to the thickness L1 of the cover plate satisfies: K2 = Ln / L1, 20% ≤ K2 ≤ 83.3%, and it satisfies: K1 + K2 = 1.

[0010] Furthermore, the thickness L1 of the cover plate satisfies: 1.5 mm ≤ L1 ≤ 3 mm; and / or, the thickness L2 of the overlapping portion satisfies: 0.5 mm ≤ L2 ≤ 2.4 mm; and / or, the thickness Ln of the boss satisfies: 0.6 mm ≤ Ln ≤ 2.5 mm.

[0011] Furthermore, the wall thickness h of the battery cell housing satisfies: 0.2 mm ≤ h ≤ 3 mm.

[0012] Furthermore, a guiding and inserting portion is provided on the boss.

[0013] Furthermore, the guiding and inserting portion includes a chamfer formed at the end of the boss.

[0014] Furthermore, along the direction in which the boss extends into the battery cell housing, the ratio K3 of the dimension L3 of the contact portion between the boss and the battery cell housing to the thickness L1 of the cover plate satisfies: K3 = L3 / L1, 16.7% ≤ K3 ≤ 80%.

[0015] Furthermore, the ratio K4 of the total value of the thickness L2 of the overlapping portion and the dimension L3 of the contact portion between the boss and the battery cell housing to the thickness L1 of the cover plate satisfies: K4 = (L2 + L3) / L1, 33.3% ≤ K4 ≤ 96.7%.

[0016] Furthermore, the dimension L3 of the contact portion between the boss and the battery cell housing satisfies: 0.5 mm ≤ L3 ≤ 2.4 mm.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] For the battery cell housing and cover plate matching structure of the present invention, by providing a boss and an overlapping portion on the cover plate, and making the cooperation form between the boss and the opening tend to zero clearance, the overlapping portion overlaps at the end of the battery cell housing, and the outer end surface of the overlapping portion is flush with the outer side surface of the battery cell housing. At the same time, by setting the ratios K1 and K2 of the thickness of the overlapping portion and the thickness of the boss to the thickness of the cover plate respectively, the matching degree between the battery cell housing and the cover plate can be improved, thereby the welding strength and the welding yield rate between the battery cell housing and the cover plate can be improved, and further the sealing performance after welding can be ensured.

[0019] In addition, setting the thickness of the cover plate between 1.5 mm and 3 mm can take into account both low cost and high welding quality, avoiding the increase in the weight of the cover plate and the structural cost caused by a relatively large thickness of the cover plate, as well as the increase in welding difficulty and the occurrence of welding cracking problems caused by a relatively small thickness of the cover plate. Setting the thickness of the overlapping part between 0.6 mm and 2.5 mm can avoid affecting the welding strength of the weld due to small size. The thickness setting of the boss can ensure the butt welding of the battery cell housing and the cover plate and ensure the sealing effect after welding.

[0020] In addition, the guiding and inserting part on the boss can facilitate the insertion of the boss into the battery cell housing, which is convenient for the assembly of the cover plate and the battery cell housing. The guiding and inserting part adopts a chamfer, which has the characteristics of simple structure, easy processing and low cost. The setting of the ratio K3 and the ratio K4 can help ensure the welding quality of the butt weld between the battery cell housing and the cover plate, avoiding the problem of unqualified welding quality caused by too small size and waste caused by too large size. In the structure with the guiding and inserting part, the size of the contact part between the boss and the battery cell housing is between 0.5 mm and 2.4 mm, which can further ensure the butt welding quality of the battery cell housing and the cover plate and improve the yield rate of the first welding.

[0021] Another object of the present invention is to provide a battery cell, in which the battery cell housing and the cover plate cooperation structure as described above is provided.

[0022] Further, positive cover plates and negative cover plates are respectively provided at both ends of the battery cell housing in the battery cell; the positive cover plate and the battery cell housing, and / or, the negative cover plate and the battery cell housing are connected by using the battery cell housing and the cover plate cooperation structure.

[0023] By adopting the above-mentioned battery cell housing and cover plate cooperation structure, the welding strength between the battery cell housing and the cover plate can be improved, and the welding yield rate of the battery cell housing and the cover plate can also be improved, and it has a good use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0025] Figure 1 is a schematic structural diagram of the battery cell housing and cover plate cooperation structure according to an embodiment of the present invention;

[0026] Figure 2 is a schematic structural diagram of the cover plate according to an embodiment of the present invention;

[0027] Figure 3 is a partial enlarged view of the battery cell housing according to an embodiment of the present invention;

[0028] Figure 4 Schematic structural diagram of the battery cell according to an embodiment of the present invention;

[0029] Figure 5 Microstructure magnification diagram of the weld position after welding the battery cell housing of this embodiment of the present invention with a cover plate of other structural forms (the left figure is a non-conforming product, and the right figure is a qualified product);

[0030] Explanation of reference numerals:

[0031] 1. Battery cell housing; 11. Open end;

[0032] 2. Cover plate; 21. Boss; 22. Lapping portion; 211. Chamfer;

[0033] 3. Battery cell electrode assembly. Detailed implementation manners

[0034] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0035] In the description of the present invention, it should be noted that if terms indicating orientation or positional relationship such as "upper", "lower", "inner", "outer", etc. appear, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, if terms such as "first", "second", etc. appear, they are also only for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0036] In addition, in the description of the present invention, unless otherwise clearly defined, the terms "installation", "connection", "connection", "connector" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in combination with specific situations.

[0037] The present invention will be described in detail below with reference to the drawings and in combination with embodiments.

[0038] This embodiment relates to a matching structure between a battery cell housing and a cover plate, which can improve the welding strength and welding yield rate between the battery cell housing 1 and the cover plate 2.

[0039] In terms of the overall composition, the matching structure between the battery cell housing and the cover plate in this embodiment is as Figure 1As shown in the figure, it includes an opening 11 formed on the battery cell housing 1, and the cover plate 2 blocks the opening 11. Moreover, a boss 21 protruding toward the side of the battery cell housing is provided on the cover plate 2, and a lapping portion 22 is formed at the root of the boss 21; the boss 21 extends into the battery cell housing 1 from the opening 11, the lapping portion 22 laps on the battery cell housing 1, the length and width of the boss 21 are respectively set corresponding to the length and width of the opening 11, the outer end surface of the lapping portion 22 is flush with the outer side surface of the battery cell housing 1, and the cover plate 2 is welded to the battery cell housing 1. And, in the assembled state of the cover plate and the battery cell housing, the ratio K1 of the thickness L2 of the lapping portion to the thickness L1 of the cover plate satisfies: K1 = L2 / L1, 16.7% ≤ K1 ≤ 80%, and the ratio K2 of the thickness Ln of the boss to the thickness L1 of the cover plate satisfies: K3 = Ln / L1, 20% ≤ K2 ≤ 83.3%, and it satisfies: K1 + K2 = 1.

[0040] At this time, through the cooperation with a nearly zero clearance between the boss 21 extending into the battery cell housing 1 and the opening 11, and making the lapping portion 22 lap on the end of the battery cell housing 1, and the outer end surface of the lapping portion is flush with the outer side surface of the battery cell housing 1. At the same time, through the settings of the ratio K1 of the thickness of the lapping portion and the ratio K2 of the thickness of the boss to the thickness of the cover plate, the matching degree between the battery cell housing 1 and the cover plate 2 can be improved, thereby the welding strength between the battery cell housing 1 and the cover plate 2 can be improved, and the welding qualification rate of the battery cell housing 1 and the cover plate 2 can also be improved, and further the post-welding sealing performance can be guaranteed.

[0041] Specifically, the battery cell housing 1 is in a cuboid structure in terms of structure, and its interior is hollow to form a receiving cavity for receiving the battery cell electrode group 3. An opening 11 is provided at the top of the battery cell housing 1, or for the battery cell housing 1 of a blade battery, openings 11 are formed at two opposite side ends thereof, the opening is rectangular, and the cover plate 2 is welded to the battery cell housing 1 and blocks the opening 11.

[0042] In this embodiment, referring to Figure 1 and Figure 2 As shown in the figure, a boss 21 protruding toward its own side is provided on the cover plate 2, and a lapping portion 22 is formed at the root of the boss 21. The lapping surface where the lapping portion 22 laps on the end of the battery cell housing 1 and the boss 21 form a stepped shape. In the assembled state, the boss 21 extends into the battery cell housing 1 from the opening 11, and the length of the boss 21 tends to be equal to the length of the opening 11, and the width of the boss 21 tends to be equal to the width of the opening 11. In this way, the boss 21 can better block the opening 11 and play a certain supporting role on the side wall of the battery cell housing 1, thereby improving the matching degree between the battery cell housing 1 and the cover plate 2, and improving the welding strength and the welding qualification rate. The lapping portion 22 laps on the battery cell housing 1, and the outer end surface of the lapping portion 22 is flush with the outer side surface of the battery cell housing 1. In this way, the appearance consistency can be guaranteed, and it is also beneficial to ensure the post-welding sealing performance.

[0043] Among them, it is worth noting that the length dimensions of the boss 21 and the open end 11 should be as equal as possible, and the width dimensions should also be as equal as possible. During the manufacturing process, due to machining errors, the tolerance ranges of the length dimension and the width dimension of the open end 11 are within ±0.1 mm, and the tolerance ranges of the length dimension and the width dimension of the boss 21 are within ±0.05 mm. Additionally, it is also worth noting that Figure 1 a, b, A, and B in

[0044] respectively indicate the width of the overlapping portion 22, the width of the boss 21, the outer width of the battery cell housing 1, and the width of the open end 11.

[0045] In this embodiment, in the assembled state of the cover plate and the battery cell housing, the ratio K1 of the thickness L2 of the overlapping portion to the thickness L1 of the cover plate satisfies: K1 = L2 / L1, 16.7% ≤ K1 ≤ 80%, and the ratio K2 of the thickness Ln of the boss to the thickness L1 of the cover plate satisfies: K2 = Ln / L1, 20% ≤ K2 ≤ 83.3%, and K1 + K2 = 1. With such a setting, it can help reduce the manufacturing cost while ensuring good welding quality.

[0046] Moreover, in this embodiment, the thickness L2 of the overlapping portion 22 satisfies: 0.5 mm ≤ L2 ≤ 2.4 mm. By setting the thickness value of the overlapping portion 22, it can avoid affecting the welding strength of the weld due to a small size. During specific implementation, the thickness of the overlapping portion 22 can be set, for example, to 0.5 mm, 0.75 mm, 0.95 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.75 mm, 1.95 mm, 2.15 mm, or 2.25 mm, and is preferably set to 0.75 mm.

[0047] In this embodiment, the thickness of the boss 21 satisfies: 0.6 mm ≤ Ln ≤ 2.25 mm. In this way, the butt welding of the battery cell housing 1 and the cover plate 2 can be ensured, and the post-welding sealing effect can be guaranteed. During specific implementation, the thickness of the boss 21 can be set, for example, to 0.6 mm, 0.75 mm, 0.95 mm, 1.1 mm, 1.3 mm, 1.5 mm, 1.75 mm, 1.95 mm, 2.15 mm, 2.25 mm, or 2.5 mm.

[0048] Refer to Figure 1 andFigure 3 As shown, the wall thickness h of the battery cell housing 1 in this embodiment satisfies: 0.2 mm ≤ h ≤ 3 mm, so that the battery cell housing 1 has better structural strength and lower manufacturing cost. Specifically in implementation, the thickness h of the battery cell housing 1 can be set to values such as 0.2 mm, 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm or 3 mm, etc. (the housing thickness does not affect the effect after welding), and no specific limitation is made here.

[0049] As a preferred implementation manner, in this embodiment, a guiding insertion portion is provided on the boss 21. The setting of the guiding insertion portion can facilitate the boss 21 to extend into the battery cell housing 1, facilitating the assembly of the cover plate 2 and the battery cell housing 1. Specifically, as Figure 1 and Figure 2 shown, the guiding insertion portion includes a chamfer 211 formed at the end of the boss 21. The guiding insertion portion adopts the structural form of the chamfer 211, which has the characteristics of simple structure, easy processing and manufacturing, and low cost.

[0050] In this embodiment, a chamfer 211 is provided at the end of the boss 21. At this time, along the direction in which the boss 21 extends into the battery cell housing 1, the ratio K3 of the dimension L3 of the contact part between the boss and the battery cell housing to the thickness L1 of the cover plate satisfies: K3 = L3 / L1, 16.7% ≤ K3 ≤ 80%. Further, the ratio K4 of the total value of the thickness L2 of the overlapping portion and the dimension L3 of the contact part between the boss and the battery cell housing to the thickness L1 of the cover plate satisfies: K4 = (L2 + L3) / L1, 33.3% ≤ K4 ≤ 96.7%. The settings of the ratio K3 and the ratio K4 can help ensure the welding quality of the butt weld between the battery cell housing and the cover plate, avoiding the problem of unqualified welding quality caused by too small dimensions and waste caused by too large dimensions.

[0051] Specifically in implementation, the dimension L3 of the contact part between the boss 21 and the battery cell housing 1 satisfies: 0.5 mm ≤ L3 ≤ 2.4 mm. And preferably, L3 is 0.95 mm. In this way, it can ensure that the boss 21 is smoothly assembled into the opening 11, and can further ensure the butt welding quality between the battery cell housing 1 and the cover plate 2, and can improve the yield rate of the first welding. At this time, the distance L4 of the chamfer 211 in the direction in which the boss 21 extends into the battery cell housing 1 is between 0.1 mm and 0.2 mm, and preferably 0.3 mm.

[0052] In this embodiment, when the battery cell housing and the cover plate are specifically assembled and welded, a pre-spot welding process is first performed on the periphery of the cover plate and the battery cell housing before the welding process, so that the cover plate is pre-fixed on the battery cell housing, and the pre-spot welds will cover the gap formed by the cooperation between the cover plate and the battery cell housing. And the assembly gap between the cover plate and the battery cell housing can be ensured to be within 0.15 mm (when the assembly gap is greater than 0.15 mm, that is, when the gap is large, the effect of laser pre-spot welding will be poor, resulting in low shell-cover welding strength and a pressure resistance strength lower than 1.2 Mpa after laser peripheral welding). This gap can ensure the welding effect of pre-spot welding, and then ensure the welding strength after welding the periphery of the battery cell housing and the battery cell cover plate. The welding strength, that is, the pressure resistance strength, is greater than 1.2 Mpa, and the helium leak detection rate of the battery after peripheral welding is less than 1*10 -7 Pa·m 3 / s.

[0053] The following verifies through multiple examples and comparative examples in Table 1 and Table 2 that the matching structure of the battery cell housing and the cover plate of the present invention can better improve the welding quality and welding airtightness. Among them, the battery cell housing 1 has the same size specification. After the battery cell housing 1 is respectively assembled with cover bodies of different sizes (different L1, L2, L3, L4), laser butt welding is performed. The specific size specifications are shown in Table 1 and Table 2 as follows:

[0054]

[0055] Table 2

[0056]

[0057] From the data in the above table, it can be seen that compared with 2#, 4#, and 5#, the cover plate thicknesses are all 1.5 mm, and the effects after their respective welding with the housing are as follows: The L3 size of the 4# cover plate is 0.45 mm, and the L2 size of the 5# cover plate is 0.45 mm, and the sizes are relatively small. After laser welding the cover plate and the housing, welding beads appear at the welding part (the L3 size is small, and the melted part size forms welding beads after laser welding). The strength of the housing after welding, that is, the pressure resistance strength, is lower than 1.2 Mpa, and even lower than 1.0 Mpa. The helium leak detection rate after welding is higher than 1*10 -7 Pa·m 3 / s. Compared with 5#, 11#, and 12#, the L2 size of the cover plate is 0.45 mm, and the size is relatively small. After laser welding the cover plate and the housing, welding beads appear at the welding part, and the welding strength and helium leak detection rate do not meet the requirements.

[0058] Compared with 1#, 6#, and 7#, the cover plate thicknesses are all 2 mm, and the effects after their respective welding with the housing are as follows: The L3 size of the 7# cover plate is 0.45 mm, and the size is relatively small. Similarly, welding beads appear at the welding part, and the welding strength and helium leak detection rate do not meet the requirements.

[0059] For Covers 3#, 8#, 9#, and 10# with the same thickness of 3 mm, the effects after welding them to the housing are as follows: The L3 dimension of Cover 8# is 0.45 mm, which is relatively small. Welding beads appear at the same welding position, and the welding strength and helium leak detection rate do not meet the requirements. The L3 dimension of Cover 10# is 0.5 mm, and no welding beads appear at the laser butt welding position, and the overall welding airtightness is good.

[0060] After Covers 2 of 1#, 2#, and 3# are welded to Cell Housing 1 respectively, no welding beads appear at the laser butt welding position, and the overall welding airtightness is good. However, after the cover of 4# is laser welded, welding beads appear at the welding position, and the overall welding airtightness is poor.

[0061] See Figure 5 as shown. Among them, the left figure is the enlarged metallographic structure diagram of the weld position after the cell housing is welded to the cover of other structural forms, and the right figure is the enlarged metallographic structure diagram of the weld position after the cell housing and the cover matching structure of this embodiment are welded. Through Figure 5 comparing the left and right figures in, it can be seen that welding beads appear after welding in the left figure, and the welding quality is unqualified. No welding beads appear after welding in the right figure, and the welding quality is good.

[0062] From the above analysis, it can be seen that the L2 dimension and L3 dimension in the cover must be greater than 0.5 mm. When L2 is taken as 0.75 mm and L3 is taken as 0.65 mm in the design scheme, the welding requirements are met. The value of L4 can be taken as more than 0.1 mm (which can be set with reference to the cover thickness). The minimum value of the cover thickness dimension can be 0.75 mm + 0.65 mm + 0.1 mm = 1.5 mm; considering the problem that the cover thickness affects the cover strength, the general value in the industry is 2.0 mm (which already meets the welding standard). Selecting a cover with a thickness of 3 mm can better meet the welding strength and sealing requirements, but it will increase the material cost. Therefore, Cover 2 of 1# is the preferred matching dimension.

[0063] The cell housing and cover matching structure of this embodiment can increase the matching degree between the cell housing 1 and the cover 2, improve the welding yield rate of the cell housing 1 and the cell cover 2, and also reduce the material cost and improve the production efficiency by restricting and defining the matching dimensions between the cover 2 and the cell housing 1.

[0064] In addition, this embodiment also relates to a cell, and the cell is provided with the above-mentioned cell housing and cover matching structure.

[0065] As Figure 4As shown in the figure, in the battery cell of this embodiment, a positive electrode cover plate 2 and a negative electrode cover plate 2 are respectively provided at both ends of the battery cell housing 1, and the positive electrode cover plate 2 and the negative electrode cover plate 2 are respectively welded to both ends of the battery cell housing 1. The above-mentioned cooperation structure between the battery cell housing and the cover plate is used to connect between the positive electrode cover plate 2 and the battery cell housing 1, and between the negative electrode cover plate 2 and the battery cell housing 1. That is to say, bosses 21 and overlapping portions 22 are provided on both the positive electrode cover plate 2 and the negative electrode cover plate 2. The bosses 21 and overlapping portions 22 on the positive electrode cover plate 2, and the bosses 21 and overlapping portions 22 on the negative electrode cover plate 2 are respectively assembled and matched with the openings 11 at both ends of the battery cell housing 1.

[0066] By adopting the above-mentioned cooperation structure between the battery cell housing and the cover plate, the welding strength between the battery cell housing 1 and the cover plate 2 can be improved, and the welding yield of the battery cell housing 1 and the cover plate 2 can also be improved, and it has a very good use effect.

[0067] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A matching structure between a battery cell housing and a cover plate, characterized in that: it includes an opening formed on the battery cell housing; a boss protruding toward the side of the battery cell housing is provided on the cover plate, and a lapping portion is formed at the root of the boss; the boss extends into the battery cell housing from the opening, the lapping portion laps on the battery cell housing, the length and width of the boss are respectively set corresponding to the length and width of the opening, the length of the boss tends to be equal to the length of the opening, the width of the boss tends to be equal to the width of the opening, the tolerance range of the length dimension and width dimension of the opening is within ±0.1 mm, the tolerance range of the length dimension and width dimension of the boss is within ±0.05 mm, the outer end face of the lapping portion is flush with the outer side face of the battery cell housing, and the cover plate is welded to the battery cell housing; in the assembled state of the cover plate and the battery cell housing, the ratio K1 of the thickness L2 of the lapping portion to the thickness L1 of the cover plate satisfies: K1 = L2 / L1, 16.7% ≤ K1 ≤ 80%, the ratio K2 of the thickness Ln of the boss to the thickness L1 of the cover plate satisfies: K2 = Ln / L1, 20% ≤ K2 ≤ 83.3%, and it satisfies: K1 + K2 = 1; a guiding and inserting portion is provided on the boss, and the guiding and inserting portion includes a chamfer formed at the end of the boss; along the direction in which the boss extends into the battery cell housing, the ratio K3 of the dimension L3 of the contact portion between the boss and the battery cell housing to the thickness L1 of the cover plate satisfies: K3 = L3 / L1, 16.7% ≤ K3 ≤ 80%; the thickness L1 of the cover plate satisfies: 1.5 mm ≤ L1 ≤ 3 mm; and / or, the thickness L2 of the lapping portion satisfies: 0.5 mm ≤ L2 ≤ 2.4 mm; and / or, the thickness Ln of the boss satisfies: 0.6 mm ≤ Ln ≤ 2.5 mm; the wall thickness h of the battery cell housing satisfies: 0.2 mm ≤ h ≤ 3 mm; the ratio K4 of the total value of the thickness L2 of the lapping portion and the dimension L3 of the contact portion between the boss and the battery cell housing to the thickness L1 of the cover plate satisfies: K4 = (L2 + L3) / L1, 33.3% ≤ K4 ≤ 96.7%; the dimension L3 of the contact portion between the boss and the battery cell housing satisfies: 0.5 mm ≤ L3 ≤ 2.4 mm.

2. A battery cell, characterized in that: the battery cell is provided with the matching structure between the battery cell housing and the cover plate according to claim 1.

3. The battery cell according to claim 2, characterized in that: positive cover plates and negative cover plates are respectively provided at both ends of the battery cell housing in the battery cell; between the positive cover plate and the battery cell housing, and / or, between the negative cover plate and the battery cell housing, the matching structure between the battery cell housing and the cover plate is adopted for connection.

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