Cover plate assembly and battery cell

Abstract

The present invention relates to the field of battery technology, and in particular to a cover plate assembly and a battery cell. The cover plate assembly includes: a pole having a protruding abutting portion; a cover plate body is provided with an opening, and a portion of the pole extends out of the opening; a seal is crimped between the abutting portion and the cover plate body; a welding piece is sleeved on the circumferential side wall of the pole extending out of the opening and is welded to the pole to form a welding portion, and the penetration depth A1 of the welding portion satisfies the following conditions: A1 ≥ 4 / 3 × P × N1 / [N2 × (N3, N4) min] wherein N1 is the contact area between the seal and the cover plate body; N2 is the circumference of the welding portion; N3 is the shear strength of the weld; N4 is the shear strength of the pole; and P is the pressure between the compressed seal and the cover plate body and the abutting portion. The present invention can ensure the welding strength and reliability of the weld and the pole, effectively avoid the occurrence of cracking of the welding portion, insufficient compressive strength of the pole, and the like, thereby improving the safety and yield rate of the battery cell.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a cover plate assembly and a battery cell. Background Art

[0002] As lithium-ion battery technology becomes increasingly mature, power batteries are widely used in electric vehicles as a new type of battery, and the performance and safety requirements of power batteries are increasing.

[0003] The battery cover is a key component in lithium-ion batteries. Its functions include welding with the shell to form a sealed cavity, leading out the positive and negative electrodes of the electrode group, and serving as an assembly carrier. The battery cover includes a bare aluminum plate, a pole, an upper plastic, a sealing ring, and a welding piece. The welding piece is welded to the pole. Poor welding between the welding piece and the pole can easily lead to cracking of the weld, insufficient compressive strength of the pole, and the upper plastic is melted and deformed by heat, affecting the insulation of the upper plastic, thereby causing problems with battery safety and low yield rate. Summary of the invention

[0004] In view of this, the purpose of the present application is to provide a cover plate assembly and a battery cell to solve the problems that the welding parts of the existing battery cover plate and the poles are unreliable, weld cracking, insufficient pole compressive strength and upper plastic melting are prone to occur, thereby causing low battery safety and yield rate problems.

[0005] A first aspect of the present invention provides a cover plate assembly, wherein the cover plate assembly comprises:

[0006] A pole having a protruding abutment portion;

[0007] The cover plate body is provided with an opening, the pole is assembled in the opening, and part of the pole extends out of the opening;

[0008] A sealing member, pressed between the abutment portion and the cover plate body;

[0009] The welding piece is arranged on the circumferential side wall of the portion of the pole extending out of the opening and is welded to the pole to form a welding portion, and the penetration depth A1 of the welding portion satisfies the following conditions:

[0010] A1≥4 / 3×P×N1 / [N2×(N3,N4)min]

[0011] Among them, N1 is the contact area between the seal and the cover body; N2 is the circumference of the side where the welding part contacts the pole; N3 is the shear strength of the weld, N3≥50MPa; N4 is the shear strength of the pole; P is the pressure between the seal, the cover body and the abutment part after compression.

[0012] Preferably, the seal is squeezed and deformed by the cover body and the abutment portion, and the compression rate of the seal is K=L1 / L2, wherein L1 is the compression amount of the seal by the cover body in the first direction, and L2 is the size of the seal before compression in the first direction.

[0013] Preferably, K=14%~56%.

[0014] Preferably, the compressed pressure P between the sealing member, the cover plate body and the abutting portion satisfies the following conditions:

[0015] P=Y1×e （Y2×K）

[0016] Among them, Y1=0.1~1; Y2=1~10.

[0017] Preferably, P=1.3MPa~30MPa.

[0018] Preferably, the width dimension T1 of the welding piece in the second direction is 1.5 mm to 8 mm;

[0019] The thickness dimension of the weldment in the first direction is T2=1.5mm~3.5mm.

[0020] Preferably, A1=0.25mm~0.8T2.

[0021] Preferably, a convex portion extending away from the cover plate body is formed at one end of the pole extending out of the opening, and the welding portion is not in contact with the convex portion;

[0022] The dimension B1 of the protrusion in the first direction is 0.2 mm to 1 mm, and / or the minimum distance B2 between the side wall of the protrusion and the side wall of the main body of the pole in the second direction is 0.8 mm to 3 mm.

[0023] Preferably, the weld width A2 of the weld portion is 0.8 mm to 3 mm.

[0024] A second aspect of the present invention provides a battery cell, comprising the cover plate assembly described in any of the above technical solutions.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The cover plate assembly of the present invention associates the penetration depth of the welding part with the contact area between the seal and the cover plate body, the circumference of the welding part, the shear strength of the welding part and the pole, and the pressure between the compressed sealing part, the cover plate body and the abutting part. When the penetration depth of the welding part satisfies the limiting condition of A1≥4 / 3×P×N1 / [N2×(N3,N4)min], the welding strength and reliability of the welding part and the pole can be guaranteed, and the occurrence of cracking of the welding part and insufficient compressive strength of the pole, etc., can be effectively avoided, thereby improving the safety and yield rate of the battery cell.

[0027] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 A schematic structural diagram of a cover plate assembly provided in an embodiment of the present invention;

[0030] Figure 2 A schematic structural diagram of a cover plate assembly provided by an embodiment of the present invention from another viewing angle;

[0031] Figure 3 A structural cross-sectional view of a cover plate assembly provided in an embodiment of the present invention;

[0032] Figure 4 for Figure 3 The enlarged structural diagram at A in the middle;

[0033] Figure 5 for Figure 3 The enlarged structural diagram at B in the middle;

[0034] Figure 6 An exploded view of the structure of the cover plate assembly provided by an embodiment of the present invention;

[0035] Figure 7 A schematic diagram of a first structure of a welding part in a cover plate assembly provided in an embodiment of the present invention;

[0036] Figure 8 A schematic diagram of a second structure of a welding part in a cover plate assembly provided in an embodiment of the present invention;

[0037] Fig. 9A third structural schematic diagram of a welding part in a cover plate assembly provided in an embodiment of the present invention;

[0038] Fig.10 A fourth structural schematic diagram of a welded part in a cover plate assembly provided in an embodiment of the present invention;

[0039] Fig.11 A schematic diagram of the stress-strain relationship between the force applied to the seal in the cover plate assembly and the compression amount of the seal in an embodiment of the present invention.

[0040] Icons: 10-pole; 11-abutment portion; 12-convex portion; 20-cover body; 21-opening; 22-liquid filling port; 23-pressure relief port; 30-sealing member; 40-welding member; 41-welding portion; 51-first insulating member; 52-second insulating member; 60-pressure relief member; 61-protective member; D1-first direction; D2-second direction. DETAILED DESCRIPTION

[0041] The following specific embodiments are provided to help the reader obtain a comprehensive understanding of the methods, devices and / or systems described herein. However, after understanding the disclosure of the present application, various changes, modifications and equivalents of the methods, devices and / or systems described herein will be apparent. For example, the order of operations described herein is merely an example, and is not limited to the order set forth herein, but in addition to the operations that must occur in a particular order, changes that will be apparent after understanding the disclosure of the present application may be made. In addition, in order to improve clarity and brevity, descriptions of features known in the art may be omitted.

[0042] The features described herein may be implemented in different forms and should not be interpreted as being limited to the examples described herein. Rather, the examples described herein have been provided only to illustrate some of the many possible ways of implementing the methods, devices and / or systems described herein that will be apparent after understanding the disclosure of the present application.

[0043] Throughout the specification, when an element (such as a layer, a region, or a substrate) is described as being “on”, “connected to”, “bound to”, “over”, or “covering” another element, it may be directly “on”, “connected to”, “bound to”, “over”, or “covering” another element, or one or more other elements may be present between them. In contrast, when an element is described as being “directly on”, “directly connected to”, “directly bound to”, “directly over”, or “directly covering” another element, there may be no other elements present between them.

[0044] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0045] Although terms such as "first," "second," and "third" may be used herein to describe various members, components, regions, layers, or portions, these members, components, regions, layers, or portions are not limited by these terms. Rather, these terms are only used to distinguish one member, component, region, layer, or portion from another member, component, region, layer, or portion. Therefore, without departing from the teachings of the examples described herein, the first member, component, region, layer, or portion referred to may also be referred to as the second member, component, region, layer, or portion.

[0046] For ease of description, spatial relational terms such as "above", "upper", "below", and "lower" may be used herein to describe the relationship of one element to another element as shown in the accompanying drawings. Such spatial relational terms are intended to include different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. For example, if the device in the accompanying drawings is turned over, an element described as being "above" or "upper" relative to another element will subsequently be "below" or "lower" relative to the other element. Therefore, the term "above" includes both "above" and "below" orientations depending on the spatial orientation of the device. The device may also be positioned in other ways (e.g., rotated 90 degrees or in other orientations), and the spatial relational terms used herein will be interpreted accordingly.

[0047] The terms used herein are only used to describe various examples and are not used to limit the present disclosure. Unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. The terms "include", "comprise" and "have" list the stated features, quantities, operations, components, elements and / or their combinations that exist, but do not exclude the existence or addition of one or more other features, quantities, operations, components, elements and / or their combinations.

[0048] Variations in the shapes shown in the drawings may occur due to manufacturing techniques and / or tolerances. Therefore, the examples described herein are not limited to the specific shapes shown in the drawings but include variations in shapes that occur during manufacturing.

[0049] The features of the examples described herein can be combined in various ways that will be apparent after understanding the disclosure of the present application. In addition, although the examples described herein have various configurations, other configurations are possible as will be apparent after understanding the disclosure of the present application.

[0050] According to a first aspect of the present invention, a cover plate assembly is provided, which specifically includes a pole 10 , a cover plate body 20 , a sealing member 30 and a welding member 40 .

[0051] Hereinafter, the specific structure of the cap plate assembly according to the present embodiment as described above will be described.

[0052] In this embodiment, if Figures 1 to 3 , Figure 5 and Figure 6 As shown, the pole 10 has a protruding abutment portion 11, specifically, the abutment portion 11 is a boss structure extending outward from the side wall of the pole 10 body; the cover body 20 is provided with an opening 21, the opening 21 is a through-hole structure penetrating the cover body 20, the pole 10 is assembled with the cover body 20 via the opening 21, and part of the pole 10 extends out of the opening 21, specifically toward the side of the cover assembly facing the outside of the battery cell, so that part of the pole 10 is protruding from the cover body 20. The cover body 20 can be a sheet structure in a rectangular or circular shape, for example, the cover body 20 can be a rectangular plain aluminum sheet.

[0053] It should be noted that the number of the poles 10 can be one or more, and the number of the openings 21 on the cover body 20 is set in a one-to-one correspondence with the number of the poles 10. When the number of the poles 10 is set to one, the battery cell is installed with at least two cover assemblies; when the number of the poles 10 is multiple, at least some of the poles 10 in the multiple poles 10 are positive poles 10, and the remaining poles 10 are negative poles 10.

[0054] Furthermore, in this embodiment, if Figures 1 to 3 , Figure 5 and Figure 6 As shown, the sealing member 30 is coated on the circumferential side wall of the pole 10 and is crimped between the abutment portion 11 and the cover plate body 20 in the first direction D1. The sealing member 30 can be an elastic sealing ring; the welding member 40 is formed of a weldable material, such as aluminum alloy, copper or ceramic, etc. The welding member 40 is formed into an annular structure and is arranged on the circumferential side wall of the portion of the pole 10 extending out of the opening 21. The welding member 40 is welded to the pole 10 to form a welding portion 41 at the connection between the welding member 40 and the pole 10.

[0055] Specifically, the welding member 40 is formed into a closed annular structure, and the outer wall of the welding member 40 can be a circular or multi-deformed structure, such as Figures 7 to 9 As shown, the shape of the inner wall of the welding member 40 can be the same as the shape of the outer wall of the welding member 40, such as Fig.10As shown, the shape of the inner wall of the welding piece 40 may be different from the shape of the outer wall of the welding piece 40, for example, the outer wall is polygonal and the inner wall is circular. In this embodiment, the inner wall of the welding piece 40 is the same shape as the outer wall of the pole 10, so as to ensure that the welding portion 41 is formed uniformly. In this embodiment, the welding portion 41 is formed into an annular structure with a penetration depth A1 and a penetration width A2.

[0056] In this embodiment, the penetration depth A1 of the weld 41 satisfies: A1≥4 / 3×P×N1 / [N2×(N3,N4)min], wherein N1 is the contact area between the seal 30 and the cover plate body 20; N2 is the circumference of the side where the weld 41 contacts the pole 10, that is, the circumference of the inner ring side of the weld 41 of the annular structure; N3 is the shear strength of the weld 40, N3≥50MPa; N4 is the shear strength of the pole 10; P is the pressure between the compressed seal 30 (that is, the assembled cover plate body 20) and the cover plate body 20 and the abutment portion 11, so that the penetration depth of the weld 41 is associated with the contact area between the seal 30 and the cover plate body 20, the circumference of the weld 41, the shear strength of the weld 40 and the pole 10, and the pressure between the compressed seal 30 and the cover plate body 20 and the abutment portion 11. Under this limited condition, the welding strength and reliability of the cover plate assembly can be guaranteed, and the safety performance of the battery can be guaranteed.

[0057] It should be noted that (N3, N4)min in the above condition means taking the minimum value of N3 and N4; it should be further noted that the values ​​of N3 and N4 can be equal.

[0058] In this embodiment, if Figure 3 and Figure 5 As shown, the weld width A2 of the welding portion 41 is 0.8 mm to 3 mm. If A2 is less than 0.8 mm, it is easy to cause insufficient welding strength between the weldment 40 and the pole 10; if A2 is greater than 3 mm, the welding power will increase accordingly, thereby increasing energy consumption and also affecting welding efficiency.

[0059] In addition, in the present embodiment, after the cover assembly is assembled, the seal 30 is clamped between the cover body 20 and the abutment portion 11 in the first direction D1, so that the seal 30 is squeezed and deformed by the cover body 20 and the abutment portion 11, and the compression rate of the seal 30 is K=L1 / L2, wherein L1 is the compression amount of the seal 30 by the cover body 20 on the first direction D1, that is, L1 is the dimension of the seal 30 compressed in the first direction D1 on the side of the seal 30 facing the cover body 20 under the action of the pressure of the cover body 20, and L2 is the dimension of the seal 30 before compression in the first direction D1, that is, L2 is the dimension of the seal 30 in the first direction D1 when it is not under pressure.

[0060] Specifically, in a preferred embodiment, K=14%~56%, thereby avoiding the problem that the seal 30 cannot be effectively sealed due to the compression rate K being too small, or the sealing ring of the battery cell is prone to cracking during the use cycle due to the compression rate K being too large, thereby avoiding safety risks such as battery cell leakage.

[0061] In the above-mentioned limiting condition of A1≥4 / 3×P×N1 / [N2×(N3,N4)min], the parameter of the pressure P is related to the compression rate K. In order to ensure the sealing effect of the sealing member 30 and the strength and reliability of the welding portion 41 at the same time, in this embodiment, the pressure P between the compressed sealing member 30 and the cover plate body 20 and the abutting portion 11 satisfies: P=Y1×e （Y2×K） ; Among them, Y1=0.1~1; Y2=1~10.

[0062] To verify the above statement P = Y1 × e （Y2×K） ; Whether the limiting conditions of Y1=0.1~1; Y2=1~10 can ensure the reliability of the sealing effect of the seal 30. Fit the actual measured parameters of the force condition and compression amount of the seal 30 in the cover assembly that meets the sealing requirements. Specifically, the fitting results are shown in Fig.11 As shown in FIG. 1 , the x-axis represents the compression of the seal 30 and the y-axis represents the force applied to the seal. According to the data of the relationship between the compression of multiple groups of seals 30 and the pressure P (i.e., the force applied to the seal 30) actually measured, the Fig.11 The solid line in the figure shows the curve, and the equation obtained by fitting the solid line is y=0.2942e （9.9213x） , Fig.11 The dotted line in is the function graph based on the fitted formula. Among them, 0.2942 is within the value range of Y1, and 9.9213 is within the value range of Y2, so it is proved that P=Y1×e （Y2×K） ; Among them, Y1=0.1~1; Y2=1~10 can ensure the sealing effect of the seal 30 and the strength and reliability of the welding part 41.

[0063] In a preferred embodiment, P=1.3MPa~15MPa, thus limiting the parameter of pressure P to be within the range of not less than 1.3MPa and not more than 15MPa, thereby ensuring that the sealing of the assembled cover assembly and the welding strength and reliability of the weld 40 and the pole 10 meet the service life and use requirements of the battery cell.

[0064] Furthermore, in this embodiment, if Figure 3 and Figure 4As shown, the width dimension T1 of the welding part 40 in the second direction D2 is 1.5 mm to 8 mm. If the dimension of T1 is less than 1.5 mm, it is easy to cause insufficient welding strength. If the dimension of T1 is greater than 8 mm, it will cause the volume and weight of the welding part 40 to increase, the cost to increase, and the excessive space occupied is not conducive to the design of the pole 10.

[0065] Furthermore, in this embodiment, if Figure 3 and Figure 4 As shown, the thickness dimension of the welding part 40 in the first direction D1 is T2=1.5mm~3.5mm. If the dimension of T2 is less than 1.5mm, it is easy to cause insufficient welding strength. If the dimension of T2 is greater than 3.5mm, it will affect the distance between the upper surface of the pole 10 (that is, the end of the pole 10 facing away from the inside of the battery cell) and the upper surface of the cover body 20 (that is, the end of the cover body 20 facing away from the inside of the battery cell). It is too large, which is not conducive to improving the volume energy density of the battery cell and will also increase the cost.

[0066] In a preferred embodiment, A1=0.25mm~0.8T2, which ensures that the penetration depth is sufficient to avoid cracking of the weld 41, thereby ensuring welding strength and reliability. A1 is not greater than 0.8T2 to ensure that the weld 40 will not be welded through and the heat generated by the welding process will not affect the insulation of the first insulating member 51 described below.

[0067] In this embodiment, if Figure 3 and Figure 4 As shown, one end of the pole 10 extending out of the opening 21 is formed with a protrusion 12 extending in a direction away from the cover plate body 20 to facilitate the connection of the pole 10 and prevent the welding portion 41 from damaging the upper surface of the pole 10 during the formation process. In this embodiment, the welding portion 41 does not contact the protrusion 12.

[0068] In a preferred embodiment, Figure 3 and Figure 4 As shown, in the first direction D1, the size B1 of the protrusion 12 is 0.2mm~1mm. If the size of B1 is less than 0.2mm, the welding portion 41 is likely to extend out of the upper surface of the pole 10, thereby affecting the connection between the pole 10 and the conductive bar; if the size of B1 is greater than 1mm, the distance between the upper surface of the pole 10 and the upper surface of the cover body 20 is larger, resulting in a lower volume energy density of the battery cell.

[0069] Further, in a preferred embodiment, as Figure 3 and Figure 4As shown, in the second direction D2, the minimum distance B2 between the side wall of the protrusion 12 and the side wall of the main body of the pole 10 is 0.8mm~3mm, that is, the distance between the protrusion 12 and the main body of the pole 10 on the same side on the axial section of the pole 10. If the size of B2 is less than 0.8mm, it is easy to damage the protrusion 12 during the forming process of the welding portion 41, thereby affecting the welding of the battery cell and the conductive bar; if the size of B2 is greater than 3mm, it is not conducive to the welding of the conductive bar and the pole 10, and it will also increase the cost.

[0070] It should be noted that the first direction D1 is the length direction of the cover plate body 20 , and the second direction D2 is the thickness direction of the cover plate body 20 .

[0071] In addition, in this embodiment, Figures 1 to 3 and Figure 6 As shown, the cover assembly also includes a first insulating member 51, a second insulating member 52 and a pressure relief member 60; wherein, the first insulating member 51 and the second insulating member 52 can both be made of plastic material to play an insulating role. Specifically, the first insulating member 51 is formed as an annular structure wrapped around the outer wall of the pole 10 and is arranged on the side of the cover body 20 facing the outside of the battery cell to separate the pole 10 and the cover body 20. The second insulating member 52 is formed as a strip structure and is arranged on the side of the cover body 20 facing the inside of the battery cell to separate the cover body 20 from the pole group inside the battery cell, thereby ensuring the insulation between the cover body 20 and the inside of the battery cell.

[0072] In this embodiment, if Figure 6 As shown, the cover body 20 is provided with a pressure relief port 23, which is a through-hole structure penetrating the cover body 20. The pressure relief member 60 is installed at the pressure relief port 23. When an abnormal situation occurs in the battery cell, the pressure inside the battery cell will increase. When the pressure increases to a preset pressure, the pressure relief member 60 will open to connect the inside of the battery cell with the outside, thereby releasing the pressure. In this embodiment, the pressure relief member 60 can be an explosion-proof valve.

[0073] Furthermore, in this embodiment, if Figure 5 As shown, the cover assembly also includes a protective member 61, which is installed on the side of the pressure relief port 23 facing the outside of the cover body 20 to protect the pressure relief member 60 and prevent the pressure relief member 60 from opening prematurely due to external impact on the pressure relief member 60.

[0074] In addition, in this embodiment, Figures 1 to 3 and Figure 5 As shown, the cover body 20 is also provided with a liquid injection port 22, which is formed as a through-hole structure penetrating the cover body 20. After the cover body 20 and the shell of the battery cell are assembled, electrolyte can be injected into the battery cell through the liquid injection port 22.

[0075] The following tests are performed on the specific parameters of A1, A2, P, N1, N2, N3, N4, T1, and T2 as described above for different assembled cover assemblies, as well as the performance of the cells formed after the assembly of the cover assemblies, and the reliability of the limiting condition of A1 ≥ 4 / 3 × P × N1 / [N2 × (N3, N4) min] is verified. The test results are shown in the following table:

[0076] A1 / mm A2 / mm P / MPa <![CDATA[N1 / mm 2 ]]> N2 / mm N3 / MPa N4 / MPa T1 / mm T2 / mm 4 / 3×P×N1 / [N2×(N3,N4)min] result Example 1 0.15 1 5 100 60 50 50 3 2 0.222222222 The penetration depth does not meet the requirements, and the weld cracks after welding Example 2 0.25 1 5 100 60 50 50 3 2 0.222222222 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Example 3 0.45 1 5 100 60 50 50 3 2 0.222222222 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Example 4 0.68 0.21 5 100 60 50 50 3 2 0.222222222 The weld width does not meet the requirements, and the weld cracks after welding Example 5 0.68 0.8 5 60 40 50 50 3 2 0.2 The weld width meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt Example 6 0.68 1 5 10 20 50 50 3 2 0.06666667 The weld width meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt Example 7 0.68 1.8 5 200 200 50 50 3 2 0.13333333 The weld width meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt Example 8 0.68 2.4 5 250 400 50 50 3 2 0.8333333 The weld width meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt Example 9 0.68 3 5 100 60 50 50 3 2 0.222222222 The weld width meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt Example 10 0.68 3.5 5 100 60 50 50 3 2 0.222222222 The weld width meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, the first insulating part does not melt, the welding energy consumption is large, and it is not recommended to use Embodiment 11 0.68 1 5 100 60 50 50 3 1.2 0.222222222 The welding parts are not rigid enough. The welding parts of the poles are greatly deformed after the pressure of 1.2MPa. The poles cannot be welded to the busbars. The first insulating part does not melt. Example 12 0.68 1 5 100 60 50 50 3 1.5 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 13 0.68 1 5 100 60 50 50 3 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 14 0.68 1 5 100 60 50 50 3 2.5 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 15 0.68 1 5 100 60 50 50 3 3 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Example 16 0.68 1 5 100 60 50 50 3 3.5 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 17 0.68 1 5 100 60 50 50 3 4 0.222222222 The pole welded parts are deformed after the pressure of 1.2MPa, and the first insulating part is not melted. The cost is high and it is not recommended to use Embodiment 18 0.68 1 5 100 60 50 50 1.3 2 0.222222222 The pole welded parts were deformed significantly after the pole was subjected to a pressure of 1.2 MPa, which affected the welding between the pole and the conductive bar; the edge of the first insulating part was melted. Embodiment 19 0.68 1 5 100 60 50 50 1.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 20 0.68 1 5 100 60 50 50 2.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 21 0.68 1 5 100 60 50 50 3.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 22 0.68 1 5 100 60 50 50 4.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 23 0.68 1 5 100 60 50 50 5.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 24 0.68 1 5 100 60 50 50 6.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 25 0.68 1 5 100 60 50 50 7.5 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 26 0.68 1 5 100 60 50 50 8 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt. Embodiment 27 0.68 1 5 100 60 50 50 9 2 0.222222222 The pole welded parts did not deform after the pressure of 1.2MPa, and the first insulating part did not melt, which affects the pole design and is not recommended. Embodiment 28 0.95 1 5 100 60 50 50 3 2 0.222222222 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 29 1.26 1 5 100 60 50 50 3 2 0.222222222 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 30 1.6 1 5 100 60 50 50 3 2 0.222222222 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 31 1.71 1 5 100 60 50 50 3 2 0.222222222 The melting depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part is melted Embodiment 32 0.96 1 1.3 100 60 50 50 3 2 0.057777778 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 33 0.96 1 8 100 60 50 50 3 2 0.355555556 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 34 0.95 1 12 100 60 50 50 3 2 0.533333333 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 35 0.95 1 15 100 60 50 50 3 2 0.666666667 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 36 0.95 1 15 100 60 30 50 3 2 1.111111111 The shear strength is low. The welding part of the pole cracks after the pressure of 1.2MPa, the helium test fails, and the first insulation part does not melt. Embodiment 37 0.95 1 15 100 60 100 80 3 2 0.416666667 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 38 0.95 1 15 100 60 450 100 3 2 0.074074074 The penetration depth meets the requirements, the pole passes the helium test after the pressure of 1.2MPa, and the first insulating part does not melt. Embodiment 39 1 1 30 100 80 100 100 4 1.5 0.5 The penetration depth meets the requirements, the pole passes the 1.2MPa pressure test, and the first insulating part does not melt. Embodiment 40 1 2 30 100 100 200 100 5 2 0.4 The penetration depth meets the requirements, the pole passes the 1.2MPa pressure test, and the first insulating part does not melt. Embodiment 41 1 2 30 100 200 300 100 6 2 0.2 The penetration depth meets the requirements, the pole passes the 1.2MPa pressure test, and the first insulating part does not melt.

[0077] According to a cover plate assembly provided by the present invention, the penetration depth of the welding part is associated with the contact area between the seal and the cover plate body, the circumference of the welding part, the shear strength of the welding part and the pole, and the pressure between the compressed sealing part and the cover plate body and the abutment part. When the penetration depth of the welding part satisfies the limiting condition of A1≥4 / 3×P×N1 / [N2×(N3,N4)min], the welding strength and reliability of the welding part and the pole can be guaranteed, and the occurrence of welding part cracking, insufficient pole pressure resistance and the like can be effectively avoided, thereby improving the safety and yield rate of the battery cell.

[0078] A battery cell provided according to the present invention includes the cover plate assembly as described above, and thus has all the beneficial effects of the cover plate assembly as described above, which will not be described in detail herein.

[0079] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A cover plate assembly, characterized in that: The cover plate assembly comprises: A pole having a protruding abutment portion; The cover plate body is provided with an opening, the pole is assembled in the opening, and part of the pole extends out of the opening; A sealing member, pressed between the abutment portion and the cover plate body; The welding piece is arranged on the circumferential side wall of the portion of the pole extending out of the opening, and is welded to the pole to form a welding portion, the fusion width A2 of the welding portion is 0.8 mm to 3 mm; the fusion depth A1 of the welding portion satisfies the following conditions: A1≥4 / 3×P×N1 / [N2×(N3,N4)min] Wherein, N1 is the contact area between the seal and the cover body; N2 is the circumference of the side where the welding part contacts the pole; N3 is the shear strength of the weld, N3≥50MPa; N4 is the shear strength of the pole; P is the pressure between the seal, the cover body and the abutment part after compression, P=1.3MPa~30MPa; The width dimension T1 of the weldment in the second direction is 1.5 mm to 8 mm; The thickness dimension of the weldment in the first direction is T2=1.5mm~3.5mm.

2. The cover plate assembly according to claim 1, characterized in that: The seal is squeezed and deformed by the cover body and the abutment portion, and the compression rate of the seal is K=L1 / L2, wherein L1 is the compression amount of the seal by the cover body in the first direction, and L2 is the size of the seal before compression in the first direction.

3. The cover plate assembly according to claim 2, characterized in that: K=14%~56%。 4. The cover plate assembly according to claim 2, characterized in that: The pressure P between the compressed seal, the cover plate body and the abutment portion satisfies the following conditions: P=Y1×e （Y2×K） Among them, Y1=0.1~1; Y2=1~10.

5. The cover plate assembly according to claim 1, characterized in that: A1=0.25mm~0.8T2.

6. The cover plate assembly according to claim 1, characterized in that: One end of the pole extending out of the opening is formed with a convex portion extending away from the cover plate body, and the welding portion is not in contact with the convex portion; The dimension B1 of the protrusion in the first direction is 0.2 mm to 1 mm, and / or the minimum distance B2 between the side wall of the protrusion and the side wall of the main body of the pole in the second direction is 0.8 mm to 3 mm.

7. A battery cell, characterized in that: The invention comprises the cover plate assembly according to any one of claims 1 to 6.

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