Cover plate assembly and battery cell

Abstract

The present invention relates to the technical field of batteries, and in particular to a cover plate assembly and a battery cell. The cover plate assembly comprises: a terminal, which has a protruding abutting portion; a cover plate body, which has an opening through which the terminal partially extends out; a sealing member, which is pressed between the abutting portion and the cover plate body; and a welding member, which is sleeved on the circumferential side wall of the portion of the terminal extending out through the opening and is welded and connected to the terminal to form a welding portion, wherein the penetration depth A1 of the welding portion satisfies the following condition: A1≥4 / 3×P×N1 / [N2×(N3,N4)min], where N1 is the contact area between the sealing member and the cover plate body, N2 is the perimeter of the welding portion, N3 is the shear strength of the welding member, N4 is the shear strength of the terminal, and P is the pressure between the compressed sealing member and the cover plate body and the abutting portion. The present invention can ensure the welding strength and reliability of the welding member and the terminal, and effectively prevent cracking of the welding portion, insufficient compressive strength of the terminal, etc., thereby improving the safety and yield of the battery cell.

Description

Cover plate assembly and battery cell

[0001] Cross-reference to related applications

[0002] The present application claims priority to the Chinese patent application No. 202411355565.1, filed on September 27, 2024, entitled "Cover plate assembly and battery cell", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a cover plate assembly and a battery cell. BACKGROUND

[0004] With the increasing maturity of lithium ion battery technology, power batteries are widely used in electric vehicles as new batteries, and the performance and safety requirements of power batteries are increasingly high.

[0005] The battery cover plate is a key accessory in lithium ion batteries, which functions to be welded with the shell to form a sealed cavity, lead out the positive and negative poles of the pole group, and serve as an assembly carrier. The battery cover plate includes an aluminum plate, a pole, an upper plastic, a sealing ring, and a welding piece. The welding piece is welded with the pole, and poor welding between the welding piece and the pole can easily lead to cracking of the weld, insufficient pressure resistance of the pole, and deformation of the upper plastic due to heat melting, which affects the insulation of the upper plastic, thereby causing low safety and yield of the battery. SUMMARY

[0006] Therefore, the present application aims to provide a cover plate assembly and a battery cell to solve the problem of unreliable welding between the welding piece and the pole of the existing battery cover plate, which can easily lead to cracking of the weld, insufficient pressure resistance of the pole, and melting of the upper plastic, thereby causing low safety and yield of the battery.

[0007] The present application provides a cover plate assembly in a first aspect, wherein the cover plate assembly comprises:

[0008] a pole having a protruding abutting portion;

[0009] a cover plate body provided with an opening, the pole being assembled in the opening, and part of the pole extending out of the opening;

[0010] a sealing piece being crimped between the abutting portion and the cover plate body;

[0011] a welding piece being arranged on the circumferential side wall of the part of the pole extending out of the opening, and being welded with the pole to form a welding portion, the penetration depth A1 of the welding portion satisfying the following condition: A1≥4 / 3×P×N1 / [N2×(N3,N4)min]

[0012] N1 is the contact area of the sealing member and the cover plate body; N2 is the circumference of the side of the welding part in contact with the pole column; N3 is the shear strength of the welding part, N3≥50MPa; N4 is the shear strength of the pole column; P is the pressure between the compressed sealing member and the cover plate body and the abutting part.

[0013] Preferably, the sealing member is extruded and deformed by the cover plate body and the abutting part, and the compression rate K=L1 / L2 of the sealing member, wherein L1 is the compression amount of the sealing member in the first direction by the cover plate body, and L2 is the size of the sealing member before compression in the first direction.

[0014] Preferably, K=14%~56%.

[0015] Preferably, the pressure P between the compressed sealing member and the cover plate body and the abutting part satisfies the following condition: P=Y1×e (Y2×K)

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

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

[0018] Preferably, the width dimension T1 of the welding part in the second direction is 1.5mm~8mm.

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

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

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

[0022] The size B1 of the convex part in the first direction is 0.2mm~1mm, and / or the minimum distance B2 between the side wall of the convex part in the second direction and the side wall of the main body of the pole column is 0.8mm~3mm.

[0023] Preferably, the fusion width A2 of the welding part is 0.8mm~3mm.

[0024] The second aspect of the present application provides an electric core comprising the cover plate assembly of any of the above technical solutions.

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

[0026] The cover plate assembly of the present application relates the penetration of the welding portion to the contact area of the sealing member and the cover plate body, the welding portion circumference, the shear strength of the welding member and the pole, and the pressure between the compressed sealing member and the cover plate body and the abutting portion, and in the case that the penetration of the welding portion satisfies the limited condition of A1>=4 / 3xPxN1 / [N2x(N3,N4)min], the welding strength and reliability of the welding member and the pole can be ensured, the cracking of the welding portion and the insufficient pressure strength of the pole can be effectively avoided, and thus the safety and yield of the battery cell are improved.

[0027] In order to make the above objectives, characteristics and advantages of the present application more apparent, clear and easy to understand, the following preferred embodiments are specifically described below, and the accompanying drawings are referred to for detailed description. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or the prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0029] Fig. 1 is a structural schematic view of the cover plate assembly provided by the embodiment of the present application;

[0030] Fig. 2 is a structural schematic view of the cover plate assembly provided by the embodiment of the present application from another perspective;

[0031] Fig. 3 is a structural sectional view of the cover plate assembly provided by the embodiment of the present application;

[0032] Fig. 4 is an enlarged structural schematic view of A in Fig. 3;

[0033] Fig. 5 is an enlarged structural schematic view of B in Fig. 3;

[0034] Fig. 6 is an exploded view of the cover plate assembly provided by the embodiment of the present application;

[0035] Fig. 7 is a first structural schematic view of the welding member in the cover plate assembly provided by the embodiment of the present application;

[0036] Fig. 8 is a second structural schematic view of the welding member in the cover plate assembly provided by the embodiment of the present application;

[0037] Fig. 9 is a third structural schematic view of the welding member in the cover plate assembly provided by the embodiment of the present application;

[0038] Fig. 10 is a fourth structural schematic view of the welding member in the cover plate assembly provided by the embodiment of the present application;

[0039] Fig. 11 is a stress-strain relationship diagram of the stress of the sealing member and the compression amount of the sealing member in the cover plate assembly provided by the embodiment of the application.

[0040] Fig. 11 is a stress-strain relationship diagram of the stress of the sealing member and the compression amount of the sealing member in the cover plate assembly provided by the embodiment of the application. DETAILED DESCRIPTION

[0041] The following detailed description is presented to aid in understanding the method, apparatus and / or system described herein. It is not intended to limit the method, apparatus and / or system described herein to the exact construction, examples, or uses described herein. Various changes, modifications, and equivalents can be made to the method, apparatus and / or system described herein, with the scope of the application being defined by the claims and the equivalents thereof. For example, the order of the operations described herein can be altered, except that the operations must occur in the specific order as necessary to implement the disclosed method, apparatus and / or system. Furthermore, features known to those in the art can be omitted for the sake of brevity and clarity.

[0042] The features described herein can be implemented in different forms and should not be construed as limited to the examples described herein. Rather, these examples have been provided so that this disclosure will be thorough and complete, and will fully convey the scope of the method, apparatus and / or system to others skilled in the art. Further, the features described herein can be implemented in a variety of different ways and should not be construed as limited to the examples described herein.

[0043] Throughout the specification, when an element (such as a layer, region, or substrate) is referred to as being "on" another element, "connected to" another element, "coupled to" another element, "adjacent to" another element, or "covering" another element, it can be directly on, connected, coupled, adjacent to, or covering the other element or one or more other elements can be interposed therebetween. In contrast, when an element is referred to as being "directly on," "directly connected to," "directly coupled to," "directly adjacent to," or "directly covering" another element, there are no other elements interposed therebetween.

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

[0045] Although terms such as "first" and "second" and "third" can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. Rather, these terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, terms of a first element, component, region, layer or section described herein could also be termed a second element, component, region, layer or section without departing from the teachings of the examples.

[0046] For ease of description, spatial relationship terms, such as "on", "upper", "under", and "lower", can be used herein to describe the relationship between one element and another element as shown in the drawings. Such spatial relationship terms are intended to encompass different orientations of the device in use or operation, in addition to the orientation depicted in the drawings. For example, if the device in the drawings is turned over, an element described as on "upper" or "upper" relative to another element would then be oriented "under" or "lower" relative to the other element. Accordingly, the term "on" encompasses both an "on" and "under" orientation based on the spatial orientation of the device. The device can be oriented in other ways (e.g., rotated 90 degrees or at other orientations) and an appropriate re-interpretation of the spatial relationship terms used herein will be made.

[0047] The terminology used herein is for the purpose of describing various examples only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises", "comprising", "includes", "including" and "has", "having" as used herein, are specifically intended to be construed as open-ended terms, i.e., to mean "including, but not limited to", "including, but not limited to", "including, but not limited to" and "including, but not limited to", respectively.

[0048] Variations in shapes depicted in the drawings can occur as a result of manufacturing processes and / or tolerances. Thus, the examples described herein are not limited to the specific shapes described herein but include variations in shapes that would occur as a result of manufacturing processes.

[0049] The features of the examples described herein can be combined in a variety of ways as will be apparent after review of the disclosure. Also, while the examples described herein have a variety of configurations, other configurations are possible.

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

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

[0052] In the present embodiment, as shown in FIGS. 1-3, 5 and 6, the pole column 10 has a protruding abutting portion 11, specifically, the abutting portion 11 is a boss structure extending outwardly from the side wall of the pole column 10 body; the cover plate body 20 is provided with an opening 21, the opening 21 is a through hole structure penetrating through the cover plate body 20, the pole column 10 is assembled with the cover plate body 20 via the opening 21, and part of the pole column 10 protrudes out of the opening 21, specifically, protrudes out of the opening 21 towards the side of the cover plate assembly facing the outside of the battery cell, so that part of the pole column 10 is arranged protruding from the cover plate body 20. The cover plate body 20 can be a sheet structure of rectangular or circular shape, for example, the cover plate body 20 can be a rectangular aluminum sheet.

[0053] It should be noted that the number of pole columns 10 can be one or more, and the number of openings 21 on the cover plate body 20 is arranged one-to-one corresponding to the number of pole columns 10. When the number of pole columns 10 is one, at least two cover plate assemblies are mounted on the battery cell; when the number of pole columns 10 is multiple, at least part of the multiple pole columns 10 are positive pole columns 10, and the remaining part of the pole columns 10 are negative pole columns 10.

[0054] Further, in the present embodiment, as shown in FIGS. 1-3, 5 and 6, the sealing member 30 is wrapped around the circumferential side wall of the pole column 10 and is crimped between the abutting portion 11 and the cover plate body 20 in the first direction D1, the sealing member 30 can be a sealing ring with elasticity; the welding member 40 is formed of a weldable material, for example, aluminum alloy, copper or ceramic, etc., the welding member 40 is formed in an annular structure and is arranged on the circumferential side wall of the part of the pole column 10 protruding out of the opening 21, the welding member 40 is welded to the pole column 10 to form a welding portion 41 at the connection between the welding member 40 and the pole column 10.

[0055] Specifically, the welding member 40 is formed in a closed annular structure, the outer wall of the welding member 40 can be circular or multi-variant structure, as shown in FIGS. 7-9, the shape of the inner wall of the welding member 40 can be the same as that of the outer wall of the welding member 40, as shown in FIG. 10, the shape of the inner wall of the welding member 40 can be different from that of the outer wall of the welding member 40, for example, the outer wall is a polygon and the inner wall is a circle. In the present embodiment, the shape of the inner wall of the welding member 40 is the same as that of the outer wall of the pole column 10, so as to ensure that the welding portion 41 is formed uniformly. In the present embodiment, the welding portion 41 is formed in an annular structure with a penetration depth A1 and a penetration width A2.

[0056] In the embodiment, the penetration depth A1 of the welding portion 41 satisfies A1≥4 / 3×P×N1 / [N2×(N3,N4)min], wherein N1 is the contact area of the sealing member 30 and the cover plate body 20; N2 is the circumference of the side of the welding portion 41 in contact with the pole column 10, i.e. the circumference of the inner ring side of the annular structure of the welding portion 41; N3 is the shear strength of the welding member 40, N3≥50MPa; N4 is the shear strength of the pole column 10; and P is the pressure between the compressed sealing member 30 (i.e. the assembled cover plate body 20) and the cover plate body 20 and the abutting portion 11. In this way, the penetration depth of the welding portion 41 is associated with the contact area of the sealing member 30 and the cover plate body 20, the circumference of the welding portion 41, the shear strengths of the welding member 40 and the pole column 10, and the pressure between the compressed sealing member 30 and the cover plate body 20 and the abutting portion 11. Under this defined condition, the welding strength and reliability of the cover plate assembly can be ensured, and the safety performance of the battery can be ensured.

[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 the embodiment, as shown in FIGS. 3 and 5, the penetration width A2 of the welding portion 41 is 0.8mm-3mm. If A2 is less than 0.8mm, the welding strength of the welding member 40 and the pole column 10 can be insufficient. If A2 is greater than 3mm, the welding power will correspondingly increase, thereby increasing energy consumption and affecting the welding efficiency.

[0059] In addition, in the embodiment, after the cover plate assembly is assembled, the sealing member 30 is clamped between the cover plate body 20 and the abutting portion 11 in the first direction D1, so that the sealing member 30 is deformed by being pressed by the cover plate body 20 and the abutting portion 11. The compression ratio K of the sealing member 30 is K=L1 / L2, wherein L1 is the compression amount of the sealing member 30 by the cover plate body 20 in the first direction D1, i.e. L1 is the size of the side of the sealing member 30 facing the cover plate body 20 which is compressed in the first direction D1 under the pressure of the cover plate body 20, and L2 is the size of the sealing member 30 before compression in the first direction D1, i.e. L2 is the size of the sealing member 30 in the first direction D1 when it is not under pressure.

[0060] Specifically, in the preferred embodiment, K=14%-56%. In this way, it can be avoided that the sealing member 30 cannot be effectively sealed due to the compression ratio K being too small, or the battery cell is prone to cracking of the sealing ring during the use cycle, thereby existing the problem of safety risk such as battery cell liquid leakage.

[0061] The parameter of pressure P in the above-mentioned defined condition of A1≥4 / 3×P×N1 / [N2×(N3,N4)min] 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 part 41 at the same time, in the embodiment, the pressure P between the compressed sealing member 30 and the cover plate body 20 and the abutting part 11 satisfies: P=Y1×e (Y2 ×K) ; wherein Y1=0.1-1; Y2=1-10.

[0062] In order to verify whether the defined condition of P=Y1×e (Y2×K) ; Y1=0.1-1; Y2=1-10 can ensure the sealing effect and reliability of the sealing member 30, the actual measured parameters of the stress condition and compression amount of the sealing member 30 in the cover plate assembly meeting the sealing requirement are fitted, specifically, the fitting result is shown in FIG. 11, wherein the x-axis represents the compression amount of the sealing member 30, and the y-axis represents the stress condition of the sealing member. According to the data of the relationship between the compression amount and the pressure P (i.e. the stress of the sealing member 30) of the sealing member 30 actually measured, the curve shown by the solid line in FIG. 11 is obtained, and the formula is y=0.2942e (9.9213x) according to the curve shape of the solid line. Wherein 0.2942 is within the value range of Y1, and 9.9213 is within the value range of Y2, thus proving that P=Y1×e (Y2×K) ; Y1=0.1-1; Y2=1-10 can ensure the sealing effect of the sealing member 30 and the strength and reliability of the welding part 41.

[0063] In the preferred embodiment, P=1.3MPa-15MPa, thus limiting the parameter of pressure P in the range of not less than 1.3MPa and not more than 15MPa, thus ensuring that the sealing property of the assembled cover plate assembly and the welding strength and reliability of the welding part 40 and the pole piece 10 all meet the service life and use requirements of the battery cell.

[0064] Further, in the embodiment, as shown in FIG. 3 and FIG. 4, the width dimension T1 of the welding part 40 in the second direction D2 is 1.5mm-8mm, if the dimension of T1 is less than 1.5mm, it is easy to cause insufficient welding strength, if the dimension of T1 is greater than 8mm, it will cause the volume and weight of the welding part 40 to increase, the cost to increase, and the occupied space is too large, which is not conducive to the design of the pole piece 10.

[0065] Further, in the embodiment, as shown in FIG. 3 and FIG. 4, the thickness dimension of the welding member 40 in the first direction D1 is T2 = 1.5 mm ~ 3.5 mm, if the dimension of T2 is less than 1.5 mm, it is easy to cause insufficient welding strength, if the dimension of T2 is greater than 3.5 mm, it will affect the distance between the upper surface of the pole 10 (i.e. the end of the pole 10 facing away from the inside of the battery cell) and the upper surface of the cover plate body 20 (i.e. the end of the cover plate body 20 facing away from the inside of the battery cell), which is not conducive to the improvement of the volume energy density of the battery cell, and also increases the cost.

[0066] In the preferred embodiment, A1 = 0.25 mm ~ 0.8T2, which ensures that the penetration depth has sufficient length to avoid cracking of the welding portion 41, to ensure welding strength and reliability, and A1 is not greater than 0.8T2 to ensure that the welding member 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 as described below.

[0067] In the embodiment, as shown in FIG. 3 and FIG. 4, the 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, so as to facilitate the connection of the pole 10 and avoid damaging the upper surface of the pole 10 during the forming of the welding portion 41, in the embodiment, the welding portion 41 does not contact the protrusion 12.

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

[0069] Further, in the preferred embodiment, as shown in FIG. 3 and FIG. 4, the minimum distance B2 between the side wall of the protrusion 12 and the side wall of the main body of the pole 10 in the second direction D2, i.e. the distance between the protrusion 12 and the main body of the pole 10 on the same side in the axial cross section of the pole 10, is 0.8 mm ~ 3 mm, if the dimension of B2 is less than 0.8 mm, it is easy to cause damage to the protrusion 12 during the forming of the welding portion 41, thereby affecting the welding of the battery cell and the conductive row; if the dimension of B2 is greater than 3 mm, it is not conducive to the welding of the conductive row and the pole 10, and also increases 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] Further, in the embodiment, as shown in FIGS. 1-3 and 6, the cover plate assembly further comprises a first insulating piece 51, a second insulating piece 52 and a pressure relief piece 60; wherein the first and second insulating pieces 51 and 52 can be made of plastic material to play an insulating role, specifically, the first insulating piece 51 is formed in a ring structure covering the outer wall of the pole 10 and is arranged on the side of the cover plate body 20 facing the outside of the battery cell to separate the pole 10 and the cover plate body 20, and the second insulating piece 52 is formed in a strip structure and is arranged on the side of the cover plate body 20 facing the inside of the battery cell to separate the cover plate body 20 and the pole group inside the battery cell, thus ensuring the insulation between the cover plate body 20 and the inside of the battery cell.

[0072] In the embodiment, as shown in FIG. 6, the cover plate body 20 is provided with a pressure relief port 23, which is a through-hole structure penetrating the cover plate body 20, and the pressure relief piece 60 is installed in the pressure relief port 23; when the battery cell has an abnormal condition, the pressure inside the battery cell will increase, and when the pressure increases to a preset pressure, the pressure relief piece 60 will open to make the inside of the battery cell communicate with the outside, thereby releasing the pressure. In the embodiment, the pressure relief piece 60 can be an explosion-proof valve.

[0073] Further, in the embodiment, as shown in FIG. 5, the cover plate assembly further comprises a protection piece 61 installed on the side of the pressure relief port 23 facing the outside of the cover plate body 20 to protect the pressure relief piece 60, avoiding the situation that the impact of the outside on the pressure relief piece 60 causes the pressure relief piece 60 to open prematurely.

[0074] Further, in the embodiment, as shown in FIGS. 1-3 and 5, the cover plate body 20 is further provided with a liquid injection port 22 formed in a through-hole structure penetrating the cover plate body 20, and after the assembly of the cover plate body 20 and the shell of the battery cell, electrolyte can be injected into the inside of the battery cell through the liquid injection port 22.

[0075] The specific parameters of A1, A2, P, N1, N2, N3, N4, T1 and T2 of the assembled different cover plate assemblies and the performance detection of the battery cell formed after the assembly of the cover plate assemblies are described above, and the reliability of the limited condition A1≥4 / 3×P×N1 / [N2×(N3,N4)min] is verified, and the test detection results are shown in the following table:

[0076] According to the cover plate assembly provided by the application, the penetration of the welding portion is associated with the contact area of the sealing element and the cover plate body, the welding portion circumference, the shearing strength of the welding element and the pole, and the pressure between the compressed sealing element and the cover plate body and the abutting portion, in the case that the penetration of the welding portion satisfies the limited condition of A1 >= 4 / 3 x P x N1 / [N2 x (N3, N4)min], the welding strength and reliability of the welding element and the pole can be ensured, the cracking of the welding portion and the insufficient pressure strength of the pole can be effectively avoided, and thus the safety and yield of the battery cell are improved.

[0077] According to the battery cell provided by the application, the cover plate assembly has all the beneficial effects of the cover plate assembly, which will not be repeated here.

[0078] Finally, it should be noted that: the above-described embodiments are only specific embodiments of the present application, used to illustrate the technical solutions of the present application, and are not limiting, the protection scope of the present application is not limited thereto, although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: any person skilled in the art in the technical range disclosed by the present application can modify or easily think of changes to the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications, changes or replacements do not make the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A cover plate assembly, characterized by The cover plate assembly comprises: a pole having a protruding abutting portion; a cover plate body provided with an opening, the pole being fitted in the opening, and part of the pole extending out of the opening; a sealing member being crimped between the abutting portion and the cover plate body; a welding member being provided on a circumferential side wall of the part of the pole extending out of the opening, and being welded to the pole to form a welding portion, a penetration depth A1 of the welding portion satisfying the following condition: A1≥4 / 3×P×N1 / [N2×(N3,N4)min] wherein N1 is a contact area of the sealing member and the cover plate body; N2 is a circumference of a side of the welding portion in contact with the pole; N3 is a shear strength of the welding member, N3≥50MPa; N4 is a shear strength of the pole; and P is a pressure between the sealing member, the cover plate body and the abutting portion after compression.

2. The cover plate assembly of claim 1, wherein, The sealing member is deformed by being pressed by the cover plate body and the abutting portion, and a compression ratio K of the sealing member is K=L1 / L2, wherein L1 is a compression amount of the sealing member in a first direction by the cover plate body, and L2 is a size of the sealing member before compression in the first direction.

3. The cover plate assembly of claim 2, wherein, K＝14％～56％。 4. The cover plate assembly of claim 2, wherein, The pressure P between the compressed seal and the cover plate body and the abutment portion satisfies the following condition: P = Y1 x e (Y2×K) wherein Y1=0.1-1; and Y2=1-10.

5. The cover plate assembly of claim 4, wherein, P=1.3MPa-30MPa.

6. The cover plate assembly of claim 1, wherein, A width dimension T1 of the welding member in a second direction is 1.5mm-8mm. A thickness dimension T2 of the welding member in the first direction is 1.5mm-3.5mm.

7. The cover plate assembly of claim 6, wherein, A1=0.25mm-0.8T2.

8. The cover plate assembly of claim 1, wherein, An end of the pole extending out of the opening is formed with a protrusion extending away from the cover plate body, and the welding portion does not contact the protrusion. A size B1 of the protrusion in the first direction is 0.2mm-1mm, and / or a minimum distance B2 between a side wall of the protrusion and a side wall of a main body of the pole in a second direction is 0.8mm-3mm.

9. The cover plate assembly of claim 1, wherein, A fusion width A2 of the welding portion is 0.8mm-3mm.

10. An electric cell characterized by A cover plate assembly as claimed in any one of claims 1-9.

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