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 sheet, a sealing ring 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 sealing ring is sleeved on the second step part and is pressed between the first step part and the top cover sheet. According to the battery cover plate and the battery monomer provided by the invention, the problems that the polar column is easy to fall off from the riveting block and the sealing performance of the existing cover plate is relatively poor because the polar column is in welded connection with the riveting block and the welding position is easy to generate the conditions of welding hole explosion and the like when the battery monomer is subjected to the pressure of the outer side of the battery monomer in the existing cover plate 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 rivet block, an upper plastic, a top cover sheet and a lower plastic, and the pole passes through the rivet block, the upper plastic, the top cover sheet and the lower plastic in sequence, wherein the pole is connected to the rivet block by riveting and welding, that is, the welding area is located on the outside of the cover plate, that is, on the side away from the battery cell electrode group; however, with the above connection method, when the battery cell is subjected to external pressure (for example, when subjected to pressure from the outside of the battery cell), weld holes may easily appear at the welding position, and the pole may easily fall off from the rivet block, causing a short circuit in the battery cell, thereby causing safety accidents such as thermal runaway and fire.

[0004] In addition, the existing cover plate has poor sealing performance. Summary of the invention

[0005] The purpose of the present application is to provide a battery cover and a battery cell, so as to solve the problem that the existing cover is a welding connection between the pole and the rivet block, when the battery cell is subjected to external pressure, it is easy for weld holes to explode at the welding position, causing the pole to easily fall off the rivet block, and the existing cover has poor sealing performance.

[0006] According to the first aspect of the present application, a battery cover is provided, which includes a pole, a top cover sheet, a sealing ring 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 holes of the second plastic part and the top cover sheet in turn, and is welded to the welding hole of the connecting piece; the sealing ring is sleeved on the second step portion, and is pressed between the first step portion and the top cover sheet.

[0007] In any of the above technical solutions, further, the sealing ring includes a first ring portion and a second ring portion connected to each other, the inner diameter of the first ring portion is the same as the inner diameter of the second ring portion, and the outer diameter of the first ring portion is larger than the outer diameter of the second ring portion; the first ring portion is pressed between the first step portion and the top cover sheet; the second ring portion is pressed between the second step portion and the top cover sheet.

[0008] In any of the above technical solutions, further, the battery cover plate also includes a first plastic part and a gasket; the gasket and the first plastic part are both provided with a through hole for the second step portion to pass through, and the gasket and the first plastic part are both arranged between the top cover sheet and the connecting member; the gasket is sleeved on the second step portion, and the outer diameter of the gasket is less than or equal to the inner diameter of the through hole of the first plastic part; the gasket can support the second circle portion.

[0009] In any of the above technical solutions, further, the second step portion includes a first section and a second section connected to each other; the cross-sectional area of ​​the second section is smaller than the cross-sectional area of ​​the first section; the first section passes through the through holes of the top cover sheet and the first plastic part in sequence, the second section is welded to the welding hole of the connecting piece, and the surface formed at the connection between the first section and the second section is in contact with the connecting piece.

[0010] In any of the above technical solutions, further, the first plastic part includes an inner sinking groove connected to its own through hole, and the connecting member is arranged in the inner sinking groove.

[0011] In any of the above technical solutions, further, the molten structure formed at the welding point between the second section and the welding hole is located on a side of the second section and the welding hole away from the first step portion.

[0012] 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.

[0013] In any of the above technical solutions, further, the battery cover plate also includes a second plastic part, the second plastic part includes a side wall and a bottom 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 second step portion to pass through; the outer diameter of the first ring portion is less than or equal to the inner diameter of the through hole of the bottom wall; the side of the first step portion away from the second step portion is exposed to the outside of the second plastic part 200.

[0014] In any of the above technical solutions, a ventilation groove extending to the side wall is further provided on the inner side of the bottom wall, and the ventilation groove passes through the through hole of the bottom wall; the ventilation groove satisfies: 0.2mm≤h≤0.5mm, 0.5mm≤g≤2mm, 0.1≤h / g≤1; wherein h is the groove depth of the ventilation groove, and g is the width of the ventilation groove.

[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, a sealing ring and a connecting piece; 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 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 sealing ring is sleeved on the second step portion and is pressed between the first step portion and the top cover sheet.

[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 sealing ring is sleeved on the second step portion and is pressed (compressed) between the first step portion and the top cover sheet, so that the sealing performance of the cover plate can be effectively ensured. In other words, the sealing ring is pressed between the first step portion and the top cover sheet, and the sealing ring can seal the gap between the first step portion and the top cover sheet, so that even if the seam welding has a weld hole, the sealing ring can still ensure the sealing performance of the cover plate.

[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 1A 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 Schematic diagram of the airway direction; Figure 8 A schematic diagram showing the overall structure of a pole according to an embodiment of the present application; Fig. 9 A cross-sectional view showing a pole according to an embodiment of the present application; Fig.10 A schematic diagram showing the overall structure of a second plastic part according to an embodiment of the present application; Fig.11 A schematic diagram showing the dimensions of the ventilation groove according to an embodiment of the present application.

[0022] Icons: 100-pole; 110-first step; 120-second step; 121-first section; 122-second section; 200-second plastic part; 201-side wall; 202-bottom wall; 203-vent; 300-top cover; 400-first plastic part; 500-sealing ring; 501-first circle; 502-second circle; 600-connector; 601-melting structure; 700-gasket; 800-explosion-proof valve; 900-explosion-proof valve patch. DETAILED DESCRIPTION

[0023] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0024] The components of the embodiments of the present application generally described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the application claimed, but merely represents the selected embodiments of the present application.

[0025] Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of this application.

[0026] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] 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, that is, the welding area is located on the outside of the cover plate, that is, on the side away from the battery cell pole group; however, in the above connection method, 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 pole is easy to fall off from the riveted block, causing a short circuit in the battery cell, thereby causing safety accidents such as thermal runaway and fire. In addition, the existing cover plate has poor sealing performance.

[0029] In a first aspect, the present application provides a battery cover plate, thereby solving the problems of the existing assembly method of the cover plate, the pole being easily detached from the riveted block, and the poor sealing of the cover plate.

[0030] Refer to the following Figures 1 to 11 A battery cover according to some embodiments of the present application is described.

[0031] like Figure 1 and Figure 6As shown, the battery cover of the present application includes a pole 100, a second plastic part 200, a top cover sheet 300, a sealing ring 500 and a connector 600 (the connector 600 is preferably a welding plate); wherein the pole 100 includes a first step portion 110 and a second step portion 120 connected to each other, and the cross-sectional area of ​​the second step portion 120 is smaller than the cross-sectional area of ​​the first step portion 110; the second plastic part 200 and the top cover sheet 300 are both provided with a through hole for the second step portion 120 to pass through, and the connector 600 is provided with a welding hole for welding the second step portion 120; the first step portion 110 is provided on the second plastic part 200, and the second step portion 120 passes through the through holes of the second plastic part 200 and the top cover sheet 300 in sequence, and is welded to the welding hole of the connector 600; the sealing ring 500 is sleeved on the second step portion 120 and is pressed between the first step portion 110 and the top cover sheet 300.

[0032] That is to say, the pole 100 (second step 120) 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 thus the pole 100 is not prone to fall off, thereby reducing safety accidents.

[0033] In addition, the bottom end of the second step portion 120 of the pole 100 of the present application is welded to the welding hole of the connector 600, and the second plastic part 200, the top cover sheet 300 and the lower plastic are all press-fitted between the first step portion 110 and the connector 600. The cover plate of the present application is press-fitted by welding instead of riveting and welding in the prior art, which not only simplifies the process but also has a better assembly effect.

[0034] In addition, if Figure 6 As shown, the sealing ring 500 of the present application is sleeved on the second step portion 120 and is pressed between the first step portion 110 and the top cover sheet 300, so that the sealing performance of the cover plate can be effectively ensured. In other words, the sealing ring 500 is pressed between the first step portion 110 and the top cover sheet 300, and the sealing ring 500 can seal the gap between the first step portion 110 and the second plastic part 200, and can also seal the gap between the second plastic part 200 and the top cover sheet 300, 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.

[0035] In the embodiments of the present application, Figure 6As shown, the sealing ring 500 includes a first ring portion 501 and a second ring portion 502 connected to each other; wherein the inner diameter of the first ring portion 501 is the same as the inner diameter of the second ring portion 502, and the outer diameter of the first ring portion 501 is greater than the outer diameter of the second ring portion 502.

[0036] The first ring portion 501 is pressed between the first step portion 110 and the top cover sheet 300, and the second ring portion 502 is pressed between the second step portion 120 and the top cover sheet 300. In this way, the second ring portion 502 is insulated and can also achieve a further sealing effect.

[0037] In the embodiments of the present application, Figure 6 As shown, the battery cover plate also includes a first plastic part 400 and a gasket 700; the gasket 700 and the first plastic part 400 are both provided with a through hole for the second step portion 120 to pass through, and the gasket 700 and the first plastic part 400 are both arranged between the top cover sheet 300 and the connecting member 600; the gasket 700 is sleeved on the second step portion 120, and the outer diameter of the gasket 700 is less than or equal to the inner diameter of the through hole of the first plastic part 400, and the gasket 700 can support the second ring portion 502.

[0038] In this configuration, the function of the gasket 700 is to ensure the compression of the sealing ring 500. Because the first plastic part 400 is generally made of PP material, which is relatively soft, when the sealing ring 500 is compressed, the PP material also undergoes a certain degree of compression deformation, which will cause the sealing ring 500 to be over-pressurized or under-pressurized, and the structural dimensions and air tightness will be affected. Therefore, a hard gasket 700 is required to ensure the compression of the sealing ring 500 (the gasket 700 and the first step 110 compress the sealing ring 500). As an example, the gasket 700 can be made of hard materials such as ceramics and PPS, and is preferably made of the same material as the second plastic part 200, PPS.

[0039] Furthermore, in the embodiment of the present application, in order to ensure the flow area of ​​the pole 100 and the good assembly of the cover plate, as shown in FIG. Figure 6 As shown, the second step portion 120 includes a first section 121 and a second section 122 connected to each other, and the cross-sectional area of ​​the second section 122 is smaller than the cross-sectional area of ​​the first section 121; the first section 121 passes through the through holes of the second plastic part 200, the top cover sheet 300 and the first plastic part 400 in sequence, and the second section 122 is welded to the welding hole of the connecting member 600, and the surface formed at the connection between the first section 121 and the second section 122 is in contact with the connecting member 600.

[0040] In this embodiment, Figure 8 and Fig. 9 As shown, the first section 121 and the second section 122 included in the second step portion 120 are both cylindrical. Fig. 9As shown, the diameter of the second section 122 is smaller than the diameter of the first section 121, and the difference between the two diameters a≥0.5 mm. Thus, the first section 121 and the second section 122 included in the second step portion 120 are convenient for processing, such as convenient for extrusion or roughening.

[0041] 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 first plastic part 400 of the present application includes an inner sinking groove connected to its own through hole, and the connecting member 600 is arranged in the inner sinking groove.

[0042] Further, in the embodiments of the present application, Figure 6 As shown, the molten structure 601 formed at the welding point of the second section 122 and the welding hole is located on the side of the second section 122 and the welding hole away from the first step portion 110, 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.

[0043] In the embodiment of the present application, the second section 122 of the pole 100 is seam-welded against the connector 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 .

[0044] 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.

[0045] The experimental data are shown in the following table:

[0046] In the embodiments of the present application, Figure 6 and Fig.10 As shown, the second plastic part 200 includes a side wall 201 and a bottom wall 202. The first step portion 110 is arranged in the installation space surrounded by the side wall 201 and the bottom wall 202. The bottom wall 202 is provided with a through hole for the second step portion 120 to pass through. The outer diameter of the first ring portion 501 is less than or equal to the inner diameter of the through hole of the bottom wall 202. The side of the first step portion 110 away from the second step portion 120 is exposed to the outside. Figure 8As shown, the first step portion 110 is preferably plate-shaped, and the first section and the second section are preferably cylindrical.

[0047] That is to say, the cover plate of the present application eliminates the riveting block and the riveting process. The pole 100 of the present application is in a "T" shape. The first step portion 110 of the pole 100 is installed in the second plastic part 200, and the upper surface is exposed to the outside. The second step portion 120 passes through the through holes of the second plastic part 200, the top cover sheet 300 and the first plastic part 400 in sequence, and is welded to the welding hole of the connector 600. The second plastic part 200, the top cover sheet 300 and the lower plastic are all pressed between the first step portion 110 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.

[0048] In addition, if Fig.10 As shown, the inner side of the bottom wall 202 of the present application is provided with a venting groove 203 extending to the side wall 201, and the venting groove 203 passes through the through hole of the bottom wall 202. In this way, when the sealing ring 500 is missing, the subsequent detection means are convenient for timely detection.

[0049] Specifically, the function of the vent groove 203 is: when the cover plate is missing a sealing ring and cannot meet the requirement of <1.0*10 -7 .m 3 / s airtightness requirements, the vent groove can be used to determine whether the sealing ring is missing to prevent defective products from flowing out. If there is no vent groove and the sealing ring is missing, the cover will pass the helium test, but as time goes by, the cover will have poor sealing after being installed on the battery cell.

[0050] like Fig.11 As shown, the ventilation groove satisfies: 0.2mm≤h≤0.5mm, 0.5mm≤g≤2mm, 0.1≤h / g≤1; wherein, h is the groove depth of the ventilation groove, and g is the width of the ventilation groove.

[0051] When the groove depth h is too shallow, the feature is not obvious and the ventilation groove is not smooth; when the groove width g is too narrow, the injection mold is difficult to form; when the groove width g is too wide, it occupies the width space of the second plastic part; when the groove depth h is too deep, the strength of the second plastic part is damaged.

[0052] The experimental data are shown in the following table:

[0053] In summary, the pole 100 (second step 120) 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 thus the pole 100 is not prone to fall off, thereby reducing safety accidents.

[0054] On this basis, the cover plate of the present application cancels the riveting block and the riveting process. The pole 100 of the present application is in a "T" shape. The first step portion 110 of the pole 100 is installed in the second plastic part 200, and the upper surface is exposed to the outside. The second step portion 120 passes through the through holes of the second plastic part 200, the top cover sheet 300 and the first plastic part 400 in sequence, and is welded to the welding hole of the connector 600. The second plastic part 200, the top cover sheet 300 and the lower plastic are all pressed between the first step portion 110 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.

[0055] On this basis, the sealing ring 500 of the present application is sleeved on the second step portion 120 and pressed between the first step portion 110 and the top cover sheet 300, so that the sealing performance of the cover plate can be effectively ensured. In other words, the sealing ring 500 is pressed between the first step portion 110 and the top cover sheet 300, and the sealing ring 500 can seal the gap between the first step portion 110 and the second plastic part 200, and can also seal the gap between the second plastic part 200 and the top cover sheet 300, 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.

[0056] In the embodiments of the present application, Figures 1 to 3 As shown, the positive pole and the negative pole are respectively arranged at both ends of the battery cover plate of the present application, and the middle part of the top cover plate is used to install the explosion-proof valve 800 and the explosion-proof valve patch 900.

[0057] 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 100 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 100 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".

[0058] According to a second aspect of the present application, a battery cell is provided, comprising the battery cover plate as described above.

[0059] 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, a sealing ring 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 sealing ring is sleeved on the second step portion and is pressed between the first step portion and the top cover sheet.

2. The battery cover according to claim 1, characterized in that: The sealing ring comprises a first ring portion and a second ring portion connected to each other, the inner diameter of the first ring portion is the same as the inner diameter of the second ring portion, and the outer diameter of the first ring portion is greater than the outer diameter of the second ring portion; The first ring portion is press-fitted between the first step portion and the top cover sheet; The second ring portion is press-fitted between the second step portion and the top cover sheet.

3. The battery cover according to claim 2, characterized in that: The battery cover also includes a first plastic part and a gasket; The gasket and the first plastic part are both provided with a through hole for the second step portion to pass through, and the gasket and the first plastic part are both arranged between the top cover sheet and the connecting member; The washer is sleeved on the second step portion, and the outer diameter of the washer is smaller than or equal to the inner diameter of the through hole of the first plastic part; The washer supports the second ring portion.

4. The battery cover according to claim 3, characterized in that: The second step portion includes a first section and a second section connected to each other; The cross-sectional area of ​​the second section is smaller than the cross-sectional area of ​​the first section; The first section passes through the through holes of the top cover sheet and the first plastic part in sequence, the second section is welded to the welding hole of the connecting member, and the surface formed by the connection between the first section and the second section is in contact with the connecting member.

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

6. The battery cover according to claim 4, characterized in that: The molten structure formed at the welding point between the second section and the welding hole is located on a side of the second section and the welding hole away from the first step portion.

7. The battery cover according to claim 6, 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.

8. The battery cover according to any one of claims 2 to 7, characterized in that: The battery cover plate further includes a second plastic part, the second plastic part includes a side wall and a bottom 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 second step portion to pass through; The outer diameter of the first ring portion is smaller than or equal to the inner diameter of the through hole of the bottom wall; A side of the first step portion away from the second step portion is exposed to the outside of the second plastic part.

9. The battery cover according to claim 8, characterized in that: The inner side of the bottom wall is provided with a ventilation groove extending to the side wall, and the ventilation groove passes through the through hole of the bottom wall; The ventilation groove satisfies: 0.2mm≤h≤0.5mm, 0.5mm≤g≤2mm, 0.1≤h / g≤1; wherein h is the groove depth of the ventilation groove, and g is the width of the ventilation groove.

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

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