Battery cover plate and battery monomer

Abstract

The invention relates to the technical field of lithium batteries, in particular to a battery cover plate and a battery monomer. The battery cover plate comprises a pole, a top cover plate and a connecting piece; the pole comprises a first step part and a second step part which are connected with each other, and the cross sectional area of the second step part is smaller than that of the first step part; the top cover piece is provided with a through hole allowing the second step part to penetrate through. The connecting piece is provided with a welding hole allowing the second step part to be welded. The second step part penetrates through the through hole of the top cover sheet and is welded with the welding hole of the connecting piece; and the top cover sheet is pressed between the first step part and the connecting piece. According to the battery cover plate and the battery monomer, the problems that an existing cover plate is formed by welding connection of a pole and a riveting block, the process is complex, and when the battery monomer is subjected to outer side pressure, welding holes and explosion holes are likely to occur in the welding position, so that the pole is likely to fall off from the riveting block are solved.

Description

Technical Field

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

[0002] As lithium-ion battery technology becomes increasingly mature, lithium-ion batteries are widely used as power batteries in the field of electric vehicles. The cover of lithium-ion batteries is also an important component of lithium-ion power batteries. It not only provides protection for lithium-ion batteries in terms of safety and reliability, but also takes into account the connection between the internal chemical system of lithium-ion batteries and external modules. The battery cover of lithium-ion batteries is an important component of lithium-ion batteries. Therefore, how to ensure the stability of the battery cover has become a technical problem that needs to be solved urgently.

[0003] The existing cover plate includes a riveting block, an upper plastic, a top cover sheet and a lower plastic, and the pole passes through the riveting block, the upper plastic, the top cover sheet and the lower plastic in sequence, wherein the pole is connected to the riveting block by riveting and welding.

[0004] However, the riveting and welding method in the prior art is not only complex in process, but also has poor assembly effect. Moreover, the riveting welding area between the pole and the riveting block is located on the outside of the cover plate, that is, on the side away from the battery cell pole group; thus, when the battery cell is subjected to external pressure (for example, when subjected to pressure from the outside of the battery cell), the welding position is prone to weld holes and the pole is prone to fall off from the riveting block, causing a short circuit in the battery cell, thereby causing safety accidents such as thermal runaway and fire. Summary of the invention

[0005] The purpose of the present application is to provide a battery cover and a battery cell, thereby solving the problem that the existing cover is a connection between the pole and the riveted block by welding, which is not only complicated in process, but also when the battery cell is subjected to external pressure, weld holes are easily formed at the welding position, causing the pole to easily fall off the riveted block.

[0006] According to the first aspect of the present application, a battery cover is provided, which includes a pole, a top cover sheet and a connecting piece; the pole includes a first step portion and a second step portion connected to each other, and the cross-sectional area of ​​the second step portion is smaller than the cross-sectional area of ​​the first step portion; the top cover sheet is provided with a through hole for the second step portion to pass through, and the connecting piece is provided with a welding hole for welding the second step portion; the second step portion passes through the through hole of the top cover sheet and is welded to the welding hole of the connecting piece; the top cover sheet is pressed between the first step portion and the connecting piece.

[0007] In any of the above technical solutions, further, the battery cover plate also includes a sealing ring; the second step portion includes a first section and a second section connected to each other, the first section is connected between the first step portion and the second section, and the cross-sectional area of ​​the second section is smaller than the cross-sectional area of ​​the first section; the sealing ring is sleeved on the second section and pressed between the first section and the connecting piece.

[0008] In any of the above technical solutions, further, the sealing ring is simultaneously pressed between the top cover sheet and the connecting member, and between the first section and the connecting member.

[0009] In any of the above technical solutions, further, the battery cover plate also includes a first plastic part and a second plastic part; the first plastic part is provided with a through hole for the first section to pass through, and the second plastic part is provided with a through hole for the second section to pass through; the first plastic part is pressed between the first step portion and the top cover sheet, and the second plastic part is pressed between the top cover sheet and the connecting member, and the inner diameter of the through hole of the second plastic part is greater than or equal to the outer diameter of the sealing ring.

[0010] In any of the above technical solutions, further, the first plastic part includes a side wall, a bottom wall and an extension wall, the first step portion is arranged in an installation space surrounded by the side wall and the bottom wall, and the bottom wall is provided with a through hole for the first section to pass through; the extension wall extends from the through hole of the bottom wall toward the connecting member, the bottom wall is arranged between the first step portion and the top cover sheet, and the extension wall can compress the sealing ring together with the connecting member.

[0011] In any of the above technical solutions, further, the second step portion also includes a third section connected to the second section; the cross-sectional area of ​​the third section is smaller than the cross-sectional area of ​​the second section; the third section is welded to the welding hole of the connecting member, and the surface formed at the connection between the third section and the second section is in contact with the connecting member.

[0012] In any of the above technical solutions, further, the second plastic part includes an inner sinking groove connected to its own through hole, and the connecting member is arranged in the inner sinking groove.

[0013] In any of the above technical solutions, further, a molten structure formed at the welding point between the third section and the welding hole is located on a side of the third section and the welding hole away from the first step portion.

[0014] In any of the above technical solutions, further, 0.3mm≤b≤c, 1mm≤c≤2.5mm, 0.3≤b / c≤1; wherein b is the depth of the molten structure, and c is the thickness of the connector.

[0015] According to a second aspect of the present application, a battery cell is provided, comprising the battery cover plate as described above.

[0016] The battery cover plate of the present application includes a pole, a top cover sheet and a connector; wherein the pole includes a first step portion and a second step portion connected to each other, and the cross-sectional area of ​​the second step portion is smaller than the cross-sectional area of ​​the first step portion; the top cover sheet is provided with a through hole for the second step portion to pass through, and the connector is provided with a welding hole for welding the second step portion; the second step portion passes through the through hole of the top cover sheet and is welded to the welding hole of the connector; the top cover sheet is pressed between the first step portion and the connector.

[0017] According to the above technical features, the beneficial effects of this application are: The pole (second step portion) of the present application is welded to the welding hole of the connector, and the welding area is located on the inner side of the cover plate, that is, on the side close to the battery pole group. In this way, compared with the prior art, when the battery cell is subjected to external pressure (for example, when subjected to pressure from the outside of the battery cell), the welding position is not prone to weld holes, and the pole is not prone to fall off, thereby reducing safety accidents.

[0018] In addition, the bottom end of the second step portion of the pole of the present application is welded to the welding hole of the connector, and the top cover sheet is pressed between the first step portion and the connector. The cover plate of the present application is welded and pressed to replace the riveting and welding method in the prior art. The present application not only simplifies the process, but also has a better assembly effect.

[0019] 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

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 A schematic diagram showing an exploded structure of a battery cover according to an embodiment of the present application; Figure 2 A schematic diagram showing the overall structure of a battery cover according to an embodiment of the present application; Figure 3 Show Figure 2 A structural diagram from another perspective; Figure 4 A top view of a battery cover according to an embodiment of the present application is shown; Figure 5 Show Figure 4 AA cross-sectional diagram of ; Figure 6 Show Figure 5 A magnified schematic diagram of part A; Figure 7 Show Figure 6 A magnified schematic diagram of part B; Figure 8 A schematic diagram showing the structure of a pole according to an embodiment of the present application; Fig. 9 A schematic diagram showing the dimensions of a pole according to an embodiment of the present application.

[0022] Icons: 100-first plastic part; 101-side wall; 102-bottom wall; 103-extension wall; 200-pole; 210-first step portion; 220-second step portion; 221-first section; 222-second section; 223-third section; 300-top cover piece; 400-second plastic part; 500-sealing ring; 600-connector; 601-melting structure; 700-explosion-proof valve; 800-explosion-proof valve patch. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] As used herein, the term "and / or" includes any one of the associated listed items and any combination of any two or more items.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The features of the examples described herein may 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.

[0032] The existing cover plate includes a riveted block, an upper plastic, a top cover sheet and a lower plastic, and the pole passes through the riveted block, the upper plastic, the top cover sheet and the lower plastic in sequence, wherein the pole is connected to the riveted block by riveting and welding. However, the riveting and welding method in the prior art is not only complicated in process, but also has a poor assembly effect. Moreover, the riveted welding area between the pole and the riveted block is located on the outside of the cover plate, that is, on the side away from the battery cell pole group; in this way, when the battery cell is subjected to pressure from the outside (for example, when subjected to pressure from the outside of the battery cell), the welding position is prone to weld holes and the like, and the pole is easy to fall off from the riveted block, causing a short circuit in the battery cell, thereby causing thermal runaway, fire and other safety accidents.

[0033] In view of this, the first aspect of the present application provides a battery cover, which solves the problem that the existing cover is a connection between the pole and the riveted block by welding, which is not only complicated in process, but also easily causes welding holes to explode at the welding position when the battery cell is subjected to external pressure, causing the pole to easily fall off from the riveted block. Figures 1 to 9 A battery cover according to some embodiments of the present application is described.

[0034] like Figure 1 and Figure 6As shown, the battery cover plate of the present application includes a pole 200, a top cover sheet 300 and a connector 600 (the connector 600 is, for example, a welding plate); wherein the pole 200 includes a first step portion 210 and a second step portion 220 connected to each other, and the cross-sectional area of ​​the second step portion 220 is smaller than the cross-sectional area of ​​the first step portion 210; the top cover sheet 300 is provided with a through hole for the second step portion 220 to pass through, and the connector 600 is provided with a welding hole for welding the second step portion 220; the second step portion 220 passes through the through hole of the top cover sheet 300 and is welded to the welding hole of the connector 600; the top cover sheet 300 is pressed between the first step portion 210 and the connector 600.

[0035] That is to say, the pole 200 (second step 220) of the present application is welded to the welding hole of the connector 600, and the welding area is located on the inner side of the cover plate, that is, on the side close to the battery pole group. In this way, compared with the prior art, when the battery cell is subjected to external pressure (for example, when subjected to pressure from the outside of the battery cell), the welding position is not prone to weld holes, and the pole 200 is not easy to fall off, thereby reducing safety accidents.

[0036] In addition, the bottom end of the second step portion 220 of the pole 200 of the present application is welded to the welding hole of the connector 600, and the top cover sheet 300 is pressed between the first step portion 210 and the connector 600. The cover plate of the present application is welded and pressed to replace the riveting and welding method in the prior art, which not only simplifies the process but also has a better assembly effect.

[0037] In the embodiment of the present application, the battery cover also includes a sealing ring 500. Figure 6 and Figure 8 As shown, the second step portion 220 includes a first section 221 and a second section 222 connected to each other, the first section 221 is connected between the first step portion 210 and the second section 222, and the cross-sectional area of ​​the second section 222 is smaller than the cross-sectional area of ​​the first section 221; the sealing ring 500 is sleeved on the second section 222 and pressed between the first section 221 and the connecting piece 600.

[0038] In this way, the sealing ring 500 can effectively ensure the sealing of the cover plate. Even if weld holes or explosion holes occur in the weld, the sealing ring 500 can still ensure the sealing of the cover plate.

[0039] Preferably, in the embodiments of the present application, Figure 6 As shown, the sealing ring 500 is simultaneously pressed between the top cover sheet 300 and the connecting member 600, and between the first section 221 and the connecting member 600. That is, the sealing ring 500 can seal the gap between the top cover sheet 300 and the connecting member 600, and the gap between the first section 221 and the connecting member 600, that is, Figure 7As shown, the sealing ring 500 can block the T1 channel and the T2 channel at the same time.

[0040] In the embodiments of the present application, Figure 1 and Figure 6 As shown, the battery cover plate also includes a first plastic part 100 and a second plastic part 400. The first plastic part 100 is provided with a through hole for the first section 221 to pass through, and the second plastic part 400 is provided with a through hole for the second section 222 to pass through; the first plastic part 100 is pressed between the first step portion 210 and the top cover sheet 300, and the second plastic part 400 is pressed between the top cover sheet 300 and the connecting member 600, and the inner diameter of the through hole of the second plastic part 400 is greater than or equal to the outer diameter of the sealing ring 500. In this way, Figure 7 As shown, the cover plate of the present application is assembled by welding and pressurizing instead of riveting and welding in the prior art, which not only simplifies the process but also has a better assembly effect. Moreover, the sealing ring 500 can effectively seal the T1 channel and the T2 channel.

[0041] In the embodiments of the present application, Figure 6 As shown, the first plastic part 100 includes a side wall 101, a bottom wall 102 and an extension wall 103. The first step portion 210 is arranged in an installation space surrounded by the side wall 101 and the bottom wall 102. The bottom wall 102 is provided with a through hole for the first section 221 to pass through; the extension wall 103 extends from the through hole of the bottom wall 102 toward the connecting member 600. The bottom wall 102 is arranged between the first step portion 210 and the top cover sheet 300. The extension wall 103 can compress the sealing ring 500 with the connecting member 600.

[0042] In this way, while the bottom wall 102 of the first plastic part 100 and the extending wall 103 are insulated, the extending wall 103 can also further compress the sealing ring 500, thereby further achieving a sealing effect.

[0043] Furthermore, in the embodiment of the present application, in order to ensure the flow area of ​​the pole 200 and the good assembly of the cover plate, as shown in FIG. Figure 8 As shown, the second step portion 220 further includes a third section 223 connected to the second section 222; the cross-sectional area of ​​the third section 223 is smaller than the cross-sectional area of ​​the second section 222. Figure 6 As shown, the third section 223 is welded to the welding hole of the connecting member 600 , and the surface formed by the connection between the third section 223 and the second section 222 is in contact with the connecting member 600 .

[0044] In this embodiment, Fig. 9As shown, the first section 221, the second section 222 and the third section 223 included in the second step portion 220 are all cylindrical. The diameter of the second section 222 is smaller than the diameter of the first section 221, the diameter of the third section 223 is smaller than the diameter of the second section 222, the difference e between the diameters of the first section 221 and the second section 222 is ≥ 0.5 mm, and the difference f between the diameters of the third section 223 and the second section 222 is ≥ 0.5 mm. In this way, the first section 221, the second section 222 and the third section 223 included in the second step portion 220 are convenient for processing, such as convenient for extrusion or roughening.

[0045] Furthermore, in the embodiments of the present application, in order to increase the energy density of the single cell and the good assembly performance of the cover plate. Figure 6 As shown, the second plastic component 400 of the present application includes an inner sinking groove connected to its own through hole, and the connecting component 600 is arranged in the inner sinking groove.

[0046] Further, in the embodiments of the present application, Figure 7 As shown, the molten structure 601 formed at the welding point of the third section 223 and the welding hole is located on the side of the third section 223 and the welding hole away from the first step portion 210, that is, the molten structure 601 is located on the side close to the electrode group. In this way, compared with the prior art, not only is the process simple, but also the stability of the welding position can be further improved when the battery cell is subjected to external pressure.

[0047] In the embodiment of the present application, the third section 223 of the pole 200 is seam-welded to the connecting member 600, wherein Figure 7 As shown, b is the depth of the molten structure 601 , and c is the thickness of the connecting member 600 .

[0048] Then the battery cover plate satisfies: 0.3mm≤b≤c, 1mm≤c≤2.5mm, 0.3≤b / c≤1; if the depth b of the molten structure 601 is too small, the stabilization effect is weak; if the depth b of the molten structure 601 is too large, the solder is wasted, the processing is difficult, and the defect rate is high. If the thickness c of the connector 600 is too small, the stabilization effect is weak; if the thickness c of the connector 600 is too large, the solder and connector material are wasted, the processing is difficult, and the defect rate is high. If 0.3>b / c, the stabilization effect is weak; if b / c>1, the melting depth is too deep, burning the sealing ring.

[0049] The experimental data are shown in the following table:

[0050] In summary, the pole 200 (second step 220) of the present application is welded to the welding hole of the connector 600, and the welding area is located on the inner side of the cover plate, that is, on the side close to the battery pole group. In this way, compared with the prior art, when the battery cell is subjected to external pressure (for example, when subjected to pressure from the outside of the battery cell), the welding position is not prone to weld holes, etc., and the pole 200 is not easy to fall off, thereby reducing safety accidents.

[0051] On this basis, the side of the first step portion 210 of the present application away from the second step portion 220 is exposed to the outside. Figure 2 As shown, the first step portion 210 is preferably in a plate shape.

[0052] That is to say, the cover plate of the present application eliminates the riveting block and the riveting process. The pole 200 of the present application is in a "T" shape. The first step portion 210 of the pole 200 is installed in the first plastic part 100, and the upper surface is exposed to the outside. The second step portion 220 passes through the through holes of the first plastic part 100, the top cover sheet 300 and the second plastic part 400 in sequence, and is welded to the welding hole of the connector 600. The first plastic part 100, the top cover sheet 300 and the lower plastic are all pressed between the first step portion 210 and the connector 600. The cover plate of the present application replaces the riveting and welding method in the prior art by welding and pressurizing. The present application not only simplifies the process, but also has a better assembly effect.

[0053] On this basis, the sealing ring 500 is simultaneously pressed between the top cover sheet 300 and the connecting member 600, and between the first section 221 and the connecting member 600. That is, the sealing ring 500 can seal the gap between the top cover sheet 300 and the connecting member 600, and the gap between the first section 221 and the connecting member 600, that is, Figure 7 As shown, the sealing ring 500 can block the T1 channel and the T2 channel at the same time. In this way, even if a weld hole or a blowout hole occurs in the weld, the sealing ring 500 can ensure the sealing of the cover plate.

[0054] It is also worth mentioning that in the embodiments of the present application, Figures 1 to 3 As shown, the positive electrode column 200 and the negative electrode column 200 are respectively arranged at both ends of the battery cover plate of the present application, and the middle part of the top cover plate 300 is used to install the explosion-proof valve 700 and the explosion-proof valve patch 800.

[0055] In summary, the cover plate of the present application can meet the following requirements: When the first related component and the second related component are tested together, one of them is placed on the positive side and the other is placed on the negative side; when placed on the positive side, the pole 200 and the top cover sheet 300 must meet "2-100000Ω" or "under a voltage of 500VDC, the resistance is 0.05-100MΩ (including the endpoints)" or "under a voltage of 500VDC, the resistance>200MΩ, and, under a voltage of 1000VDC, the current<2mA"; when placed on the negative side, the pole 200 and the top cover sheet 300 must meet "under a voltage of 500VDC, the resistance>200MΩ, and, under a voltage of 1000VDC, the current<2mA".

[0056] According to a second aspect of the present application, a battery cell is provided, comprising the battery cover plate as described above.

[0057] 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 has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that any technician familiar with this technical field can still modify the technical solutions recorded in the aforementioned embodiments within the technical scope disclosed in the present application, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be covered by the protection scope of the present application.

Claims

1. A battery cover, characterized in that: The battery cover plate includes a pole, a top cover plate and a connector; The pole comprises a first step portion and a second step portion connected to each other, wherein the cross-sectional area of ​​the second step portion is smaller than the cross-sectional area of ​​the first step portion; The top cover sheet is provided with a through hole for the second step portion to pass through, and the connecting piece is provided with a welding hole for the second step portion to be welded; The second step portion passes through the through hole of the top cover sheet and is welded to the welding hole of the connecting member; The top cover sheet is press-fitted between the first step portion and the connecting member.

2. The battery cover according to claim 1, characterized in that: The battery cover also includes a sealing ring; The second step portion includes a first section and a second section connected to each other, the first section is connected between the first step portion and the second section, and the cross-sectional area of ​​the second section is smaller than the cross-sectional area of ​​the first section; The sealing ring is sleeved on the second section and is press-fitted between the first section and the connecting piece.

3. The battery cover according to claim 2, characterized in that: The sealing ring is simultaneously pressed between the top cover sheet and the connecting member, and between the first section and the connecting member.

4. The battery cover according to claim 3, characterized in that: The battery cover also includes a first plastic part and a second plastic part; The first plastic part is provided with a through hole for the first section to pass through, and the second plastic part is provided with a through hole for the second section to pass through; the first plastic part is pressed between the first step portion and the top cover piece, and the second plastic part is pressed between the top cover piece and the connecting piece, and the inner diameter of the through hole of the second plastic part is greater than or equal to the outer diameter of the sealing ring.

5. The battery cover according to claim 4, characterized in that: The first plastic part includes a side wall, a bottom wall and an extension wall, the first step portion is arranged in an installation space surrounded by the side wall and the bottom wall, and the bottom wall is provided with a through hole for the first section to pass through; The extension wall extends from the through hole of the bottom wall toward the connecting member. The bottom wall is arranged between the first step portion and the top cover sheet. The extension wall can compress the sealing ring together with the connecting member.

6. The battery cover according to any one of claims 2 to 4, characterized in that: The second step portion further includes a third section connected to the second section; The cross-sectional area of ​​the third section is smaller than the cross-sectional area of ​​the second section; The third section is welded to the welding hole of the connecting member, and a surface formed by the connection between the third section and the second section is in contact with the connecting member.

7. The battery cover according to claim 4, characterized in that: The second plastic part comprises an inner sinking groove communicated with the through hole thereof, and the connecting part is arranged in the inner sinking groove.

8. The battery cover according to claim 6, characterized in that: The molten structure formed at the welding point between the third section and the welding hole is located on a side of the third section and the welding hole away from the first step portion.

9. The battery cover according to claim 8, characterized in that: 0.3mm≤b≤c, 1mm≤c≤2.5mm, 0.3≤b / c≤1; Wherein, b is the depth of the molten structure, and c is the thickness of the connecting piece.

10. A battery cell, characterized in that: Comprising the battery cover according to any one of claims 1-9.

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