Battery cell cover plate assembly and battery cell

Abstract

The invention relates to the technical field of lithium batteries, and provides a battery cell cover plate assembly and a battery cell, the battery cell cover plate assembly comprises a cover plate body and an explosion-proof valve; an anti-explosion hole is formed in the cover plate body, a stepped counter bore is formed in one end of the anti-explosion hole, and the anti-explosion valve is fixedly connected to the stepped counter bore; the anti-explosion valve comprises a bottom wall part and a side wall part, an edge part is arranged at one end, far away from the bottom wall part, of the side wall part, and the edge part is fixed in the stepped counter bore, so that the bottom wall part protrudes out of the surface of the side, provided with the stepped counter bore, of the cover plate body; wherein the thickness of the anti-explosion valve is h, a protrusion height a is formed between the inner side surface of the bottom wall part and the step surface of the step sinking table, and a / h is 0.2-4. The explosion-proof valve is arranged to be of a protruding structure, and the pressure relief guide groove is located in the bottom wall part, so that the explosion-proof valve protrudes out of the surface in the inner side direction of the cover plate body, and the electrolyte can be prevented from making contact with the bottom wall part. And during processing, the ratio of the thickness of the anti-explosion valve to the height of the bulge is limited, so that the anti-explosion valve can be integrally formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery, and particularly relates to a cell cover plate assembly and a cell. BACKGROUND

[0002] As a power battery, lithium ion battery is widely used in electric vehicles and energy storage fields, and the performance and safety of the lithium ion battery are important issues in the industry. In the structure of the traditional square lithium battery, the cover plate body and the shell are welded and sealed, and the pole group is packaged inside, and an explosion-proof valve is arranged on the cover plate. When the cell short-circuit is out of control, the cell will react violently, and chemical gas will be generated. When the explosion-proof valve reaches the burst pressure, the explosion-proof valve will be opened to release the gas, thereby reducing the cell out-of-control time and protecting the cell safety.

[0003] In order to improve the energy density of the battery pack and optimize the battery layout, the battery inversion loading requirement is proposed. When the battery is inverted, the electrolyte in the battery will gather on the top cover under the action of gravity and flow to the explosion-proof valve. The explosion-proof valve notch explosion area is soaked in the electrolyte for a long time, which will cause corrosion, affect the explosion pressure of the explosion-proof valve, and affect the safety of the cell.

[0004] In the related art, some typical technical solutions adopt the structure of optimizing the cell shell to protect the explosion-proof valve. This way has great processing difficulty, low yield and high preparation cost. SUMMARY

[0005] The present application provides a cell cover plate assembly and a cell to solve the defect that the electrolyte in the inverted cell corrodes the explosion-proof valve, causing the safety measures to fail.

[0006] The first aspect of the present application provides a cell cover plate assembly, comprising: a cover plate body and an explosion-proof valve, an explosion-proof hole axially penetrating is formed in the cover plate body, one end of the explosion-proof hole is formed with a stepped counterbore, and the explosion-proof valve is fixedly connected in the stepped counterbore; the explosion-proof valve comprises a bottom wall part with a pressure relief guide groove and an annular side wall part integrally formed with the bottom wall part, one end of the side wall part away from the bottom wall part is integrally formed with an edge part extending along the outside of the bottom wall part, and the edge part is fixed to the inner wall of the stepped counterbore, so that the bottom wall part protrudes from the surface of the cover plate body on the side with the stepped counterbore; wherein the thickness of the explosion-proof valve is h, the distance between the surface of the bottom wall part close to the cover plate body and the step surface of the stepped counterbore in the thickness direction of the cover plate body is 0.9mm≤a≤18mm, and satisfies: 0.2≤a / h≤4.

[0007] According to the cell cover plate assembly provided by the present application, the side wall part is inclined towards the outside of the bottom wall part, and the included angle between the side wall part and the bottom wall part is 95°≤x≤130°.

[0008] The first transition surface and the second transition surface are both configured as curved surface structures.

[0009] The thickness of the cover plate body is 1mm≤h1≤5mm, and the thickness of the explosion-proof valve is 2mm≤h≤10mm.

[0010] The step height of the stepped counterbore step surface is consistent with the thickness of the explosion-proof valve.

[0011] The pressure relief guide groove is provided with a score groove, the distance between the junction of the bottom wall portion and the side wall portion and the center line of the score groove is 0.5mm≤b≤30mm, and the following condition is satisfied: 0.5≤b / a≤5, wherein a is the distance between the surface of the bottom wall portion close to the cover plate body on the thickness direction of the cover plate body and the step surface of the stepped counterbore.

[0012] The extension width of the stepped counterbore step surface in the circumferential direction of the explosion-proof hole is 0.2mm≤e≤20mm.

[0013] The thickness of the stepped counterbore step surface in the axial direction of the explosion-proof hole is 0.5mm≤h2≤4.7mm.

[0014] The extension width of the rim portion in the circumferential direction of the explosion-proof valve is 2mm≤w≤10mm.

[0015] The second aspect of the present application provides a battery cell, which comprises the battery cell cover plate assembly of any one of the above.

[0016] The battery cell cover plate assembly and the battery cell provided by the present application set the explosion-proof valve as a protruding structure, and the pressure relief guide groove is located on the bottom wall portion, so that the explosion-proof valve protrudes from the surface inside the cover plate body, thereby avoiding contact between the electrolyte and the bottom wall portion. In addition, during processing, the ratio of the thickness of the explosion-proof valve and the protruding height is limited, which is beneficial to the integral molding of the explosion-proof valve. BRIEF DESCRIPTION OF DRAWINGS

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is an exploded structural diagram of the battery cell cover plate assembly provided by the present invention.

[0019] Figure 2 This is a bottom view of the battery cell cover assembly provided by the present invention.

[0020] Figure 3 This invention provides Figure 2 Schematic diagram of the cross-sectional structure along the AA direction.

[0021] Figure 4 This invention provides Figure 3 Enlarged schematic diagram of the structure at point B.

[0022] Figure label: 10. Cover plate body; 11. Explosion-proof hole; 111. Stepped countersunk hole; 20. Explosion-proof valve; 21. Bottom wall; 211. Pressure relief guide groove; 212. Scoring groove; 22. Side wall; 23. Edge. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0024] In the description of the embodiments of the present invention, it should be noted that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the purpose of clarifying the embodiments of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of the present invention. In addition, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] In the description of the embodiments of the present invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0026] In embodiments of the present invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0027] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0028] To improve the performance and safety of lithium-ion batteries, some technologies involve inverting the battery. However, this inversion causes electrolyte to drip onto the explosion-proof valve, potentially malfunctioning it. To address this, some solutions modify the cell casing to prevent electrolyte contact with the explosion-proof valve. Common structural methods include adding sealing or protective structures. However, these methods require additional components, increasing the overall weight of the cell, complicating manufacturing, reducing yield, and raising production costs.

[0029] To address the issues in the relevant technologies, the following will be discussed in conjunction with... Figures 1-4The present invention describes a battery cell cover assembly, comprising a cover body 10 and an explosion-proof valve 20; the cover body 10 has an axially penetrating explosion-proof hole 11, one end of which forms a stepped countersunk hole 111, and the explosion-proof valve 20 is fixedly connected within the stepped countersunk hole 111; the explosion-proof valve 20 includes a bottom wall portion 21 having a pressure relief guide groove 211 and an annular side wall portion 22 integrally formed with the bottom wall portion 21, the end of the side wall portion 22 away from the bottom wall portion 21 being integrally formed The device has an edge portion 23 extending along the outer side of the bottom wall portion 21, which is fixed to the inner wall of the stepped countersunk hole 111, so that the bottom wall portion 21 protrudes from the surface of the cover plate body 10 on the side with the stepped countersunk hole 111. The thickness of the explosion-proof valve 20 is h. In the thickness direction of the cover plate body 10, the distance between the surface of the bottom wall portion 21 near the cover plate body 10 and the step surface of the stepped countersunk hole is 0.9mm≤a≤18mm, and satisfies: 0.2≤a / h≤4. When the battery cell is inverted, electrolyte will drip onto the surface of the cover plate body 10 facing the electrode group and onto the explosion-proof valve 20, thus depositing at the location of the explosion-proof valve 20, causing the pressure relief guide groove 211 on the explosion-proof valve 20 to malfunction, creating a safety hazard. In this embodiment, by setting the overall structure of the explosion-proof valve 20 as a boss structure, the bottom wall 21 with the pressure relief guide groove 211 protrudes towards the electrode group, thereby preventing electrolyte from depositing on the surface of the bottom wall 21 when inverted, thus effectively preventing the explosion-proof valve 20 from failing and improving safety performance.

[0030] Specifically, the cover plate body 10 has an inner surface and an outer surface in the thickness direction. The inner surface faces the electrode group inside the cell, and the outer surface is away from the electrode group inside the cell. An explosion-proof hole 11 is located in the middle of the cover plate body 10. The explosion-proof hole 11 is constructed as a stepped countersunk hole 111, meaning that the inner wall surface of the explosion-proof hole 11 near the inner surface has a stepped structure. The explosion-proof valve 20 is fixedly connected inside the stepped countersunk hole 111 and located at the end of the explosion-proof hole 11 near the inner surface. This design allows gas generated in the event of a short circuit in the battery to break through the explosion-proof valve 20 and be released through the explosion-proof hole 11, thus shortening the time of cell runaway and protecting the cell safety. Specifically, the explosion-proof valve 20 has a cylindrical boss structure, which allows the electrolyte on the bottom wall 21 of the explosion-proof valve 20 to flow from the boss to the cover plate body 10, thereby preventing the electrolyte from depositing. The electrolyte on the cover plate body 10 is blocked by the protruding part, preventing it from contacting the bottom wall 21 of the explosion-proof valve 20, thus improving safety performance.

[0031] The explosion-proof valve 20 is integrally stamped, meaning its bottom wall 21, side wall 22, and edge 23 are all integrally formed. Since the overall thickness of the explosion-proof valve 20 is relatively thin, it needs to have a certain protrusion height 'a' while also accommodating material flow during stamping, making the integral forming process technically challenging. This embodiment limits the ratio of the thickness 'h' of the explosion-proof valve 20 to the protrusion height 'a' formed between the inner surface of the bottom wall 21 and the stepped surface of the stepped platform to a ratio of a / h = 0.2-4. This provides the explosion-proof valve 20 with a reasonable protrusion height, effectively blocking the electrolyte around it without causing insufficient material flow space and cracking during stamping due to excessive height, thus facilitating the stamping process of the explosion-proof valve 20.

[0032] Understandably, compared to the method of adding protective components in related technologies, this embodiment directly processes the explosion-proof valve 20 into a frustum-shaped structure and limits the ratio between the protrusion height a (i.e., the distance between the surface of the bottom wall portion 21 near the cover plate body 10 and the step surface of the stepped platform in the thickness direction of the cover plate body 10) and the thickness h of the explosion-proof valve 20; so that it can be stamped and formed, and the limiting of this ratio can be used to quickly stamp and form, with a high yield rate, reducing the difficulty and cost of manufacturing, and effectively blocking the inflow of electrolyte.

[0033] In some specific implementation methods, such as Figure 4 As shown, the specific values ​​for the protrusion height 'a' are: 0.9mm, 2mm, 6mm, 8mm, 11mm, 15mm, 16mm, or 18mm. The values ​​for a / h are 0.2, 0.80, 1.0, 1.8, 2.5, 3.0, 3.5, and 4.

[0034] It should be understood that the cover body 10 of the battery cell cover plate in this invention is a sheet structure, and its thickness direction is perpendicular to the cover plate surface. Therefore, the thickness of the cover body 10 is limited to the dimension extending in the thickness direction.

[0035] In some embodiments, the sidewall portion 22 is inclined outward toward the bottom wall portion 21, and the included angle between the sidewall portion 22 and the bottom wall portion 21 is 95°≤x≤130°. When the electrolyte drips, part of it drips onto the outer surface of the bottom wall portion 21 (the surface facing the electrode group), and another part drips onto the cover plate body 10 of the outer periphery of the explosion-proof valve 20. The electrolyte located on the bottom wall portion 21 of the explosion-proof valve 20 flows through the sidewall portion 22 and eventually flows onto the cover plate body 10. In this example, the inclined setting makes the flow of electrolyte smooth, avoids electrolyte splashing, and facilitates stamping.

[0036] Specifically, the side of the explosion-proof valve 20 facing inward is defined as the inner side, and the side away from the inner side of the explosion-proof valve 20 is defined as the outer side. The explosion-proof valve 20 is integrally formed by stamping. In this embodiment, by limiting the inclined setting of the side wall portion 22, the radial width of the explosion-proof valve 20 gradually expands from the bottom wall portion 21 to the top opening, thus forming a frustum-shaped integral structure. This method enables the rapid stamping forming of the explosion-proof valve 20.

[0037] Understandably, if the inclination angle of the side wall 22 is too small, it will hinder the stamping and demolding of the explosion-proof valve 20 and easily cause scratches and aluminum shavings to adhere to the wall surface. Furthermore, it will be subject to greater force during stamping and be more prone to damage. On the other hand, if the inclination angle of the side wall 22 is too large, the pressure relief guide groove 211 will tend to move closer to the center of the bottom wall 21. This will reduce the actual effective area of ​​the explosion-proof valve 20, wasting overall space and hindering the overall layout design.

[0038] In some specific implementation methods, such as Figure 4 As shown, the included angle x between the side wall portion 22 and the bottom wall portion 21 takes the values ​​of 95°, 105°, 115°, 125° or 130°.

[0039] During the actual processing, the mold is used to limit the position, and then the punch is aligned with the base material. Under the condition of mold limitation, the base material is stamped by the stamping device, so that the base material finally forms the outer shape of the explosion-proof valve 20.

[0040] It is understandable that by using the inclined sidewall portion 22, the opening end of the explosion-proof valve 20 is made into a flared structure, which makes it easy to demold during the stamping process and has stable structural strength after connection, thus making the whole has higher stability.

[0041] In conjunction with the above embodiments, a first transition surface is formed between the side wall portion 22 and the bottom wall portion 21, and a second transition surface is formed between the side wall portion 22 and the edge portion 23. Both the first and second transition surfaces are constructed as curved surfaces. By defining the transition surfaces as curved surfaces, it is more conducive to the integral molding of the explosion-proof valve 20, and the overall structural strength of the explosion-proof valve 20 is increased.

[0042] Specifically, curved transitions guide the metal sheet to stretch evenly during stamping, reducing wrinkling or tearing and improving the yield rate. They also prevent sharp edges from causing localized wear on the stamping die, reducing the frequency of die maintenance. In practice, the design of the first and second transition surfaces can increase die life by 20%-40%. Structurally, the design of the first and second transition surfaces avoids stress concentration at right-angle joints, significantly reducing the risk of fatigue cracks.

[0043] In specific configuration, the thickness of the cover plate body 10 is 1mm ≤ h1 ≤ 5mm, and the thickness of the explosion-proof valve 20 is 2mm ≤ h ≤ 10mm. The explosion-proof valve 20 and the cover plate body are connected by laser welding for sealing. Too thin or too thick a connection will affect the assembly. In this embodiment, by limiting the thickness value, the explosion-proof valve 20 can have sufficient connection strength and facilitate installation and welding.

[0044] Specifically, the explosion-proof valve 20 is connected to the cover plate body 10 by laser welding. If its thickness is too small, it is easy to cause insufficient welding strength and connection strength risk. On the other hand, if the explosion-proof valve 20 is too thick, it is not conducive to installation, resulting in complicated procedures during installation and positioning.

[0045] The cover plate body 10 is made of light aluminum sheet, and an explosion-proof hole 11 is machined in the middle of the ring. The explosion-proof valve is made of the same material and is fixedly connected in the stepped countersunk hole. The thickness h1 of the cover plate body 10 is 1mm, 2mm, 3mm, 3.5mm, 4mm or 5mm.

[0046] Understandably, excessively thick materials may result in insufficient laser penetration depth and unsatisfactory welding effects; while excessively thin materials may be prone to deformation or cracking during welding. A thickness range of 2-10 mm is generally suitable for laser welding, ensuring a balance between weld depth and heat input, thereby obtaining a high-quality weld joint. Furthermore, the explosion-proof valve 20 needs sufficient mechanical strength to withstand internal and external pressure changes, ensuring that it does not rupture or deform under extreme pressure. A thickness range of 2-10 mm typically provides sufficient strength while maintaining appropriate weight.

[0047] In some specific implementation methods, such as Figure 4 As shown, the thickness h of the explosion-proof valve 20 can be 1mm, 2mm, 3.5mm, 6mm, 7.5mm, 8mm, 9mm or 10mm.

[0048] In specific configuration, the step height of the stepped surface of the countersunk hole 111 is consistent with the thickness of the explosion-proof valve 20. The explosion-proof valve 20 requires a seal during connection to prevent internal gas or liquid leakage. In this embodiment, the edge 23 of the explosion-proof valve 20 is connected to the stepped surface of the stepped countersunk hole 111. By setting the step height to the same height as the thickness of the explosion-proof valve 20, a tight seal is achieved, preventing gas or liquid leakage.

[0049] Specifically, on the one hand, the step height is consistent with the thickness of the explosion-proof valve 20, providing good support and stability for the valve. This ensures that the valve will not tilt or experience uneven stress under pressure, increasing the overall structural reliability. Furthermore, the step design helps distribute the pressure on the valve during operation, making the stress more even and reducing stress concentration, thereby extending its service life and ensuring its safety under extreme conditions. On the other hand, when the explosion-proof valve 20 is securely fixed to the step height that matches its thickness, the risk of seal failure is effectively reduced, ensuring the valve's normal operation. This design also facilitates connection verification, allowing for easy visual inspection to determine if the connection is in place.

[0050] In some embodiments, the pressure relief guide groove 211 is provided with a scoring groove 212. The distance between the junction of the bottom wall portion 21 and the side wall portion 22 and the center line of the scoring groove 212 is 0.5mm≤b≤30mm; and satisfies: 0.5≤b / a≤5, where a is the distance between the surface of the bottom wall portion 21 near the cover plate body 10 and the step surface of the stepped platform in the thickness direction of the cover plate body 10. The position of the pressure relief guide groove 211 is directly related to the effectiveness of the valve body. This embodiment, through the limitation of the b / a ratio, ensures a reasonable positional relationship, thereby ensuring the stable and effective function of the valve body.

[0051] Specifically, a groove 212 is provided within the pressure relief guide groove 211. This groove 212, being the weakest point, directly affects the effectiveness of the explosion-proof valve 20. That is, the ratio b / a cannot be too small. Because the greater the stamping depth, the greater the material deformation stress, the greater the distance b between the center line of the groove and the junction of the bottom wall 21 and the side wall 22 should also be increased to prevent internal material stress from affecting the normal detonation of the grooved area of ​​the explosion-proof valve 20. If the ratio is too large, the pressure relief guide groove 211 area will tend to shrink inwards towards the center, resulting in a smaller area of ​​the explosion-proof valve 20, wasting space and hindering rapid response.

[0052] In some specific implementation methods, such as Figure 4 As shown, the distance b between the junction of the wall portion 21 and the side wall portion 22 and the center line of the groove 212 takes the following values: 0.5mm, 5mm, 8.5mm, 13.5mm, 16mm, 20mm, 25mm or 30mm. The value of b / a takes the following values: 0.5, 1.2, 2, 3.5, 4 or 5.

[0053] In some embodiments, the extension width of the stepped surface of the stepped countersunk hole 111 in the circumferential direction of the explosion-proof hole 11 is 0.2mm≤e≤20mm. The explosion-proof valve 20 is welded to the stepped surface of the stepped countersunk hole 111. In this embodiment, by limiting the width of the stepped surface, it provides a sufficient welding connection area, which is beneficial for welding.

[0054] Specifically, when the edge 23 of the explosion-proof valve 20 is welded to the wall of the stepped surface during the actual connection, if it is too small, it will be difficult to play the role of positioning the explosion-proof valve 20 due to assembly tolerance, and the explosion-proof valve 20 will be unable to be positioned, and the explosion-proof valve 20 will be easy to be punctured and fall off; while if the width e is too large, it will waste materials and reduce the communication space of the explosion-proof hole 11.

[0055] In some specific implementation methods, such as Figure 4 As shown, the specific values ​​of the extension width e of the stepped surface of the stepped countersunk hole 111 are: 0.2mm, 1mm, 5mm, 8mm, 12mm, 15mm, 17mm or 20mm.

[0056] In conjunction with the above embodiments, the thickness of the stepped surface of the countersunk hole 111 in the axial direction of the explosion-proof hole 11 is 0.5mm≤h2≤4.7mm. When the explosion-proof valve 20 is connected, the edge portion 23 of the explosion-proof valve 20 is welded to the stepped surface of the countersunk hole 111. This embodiment, by limiting the step surface, makes its connection strength higher and facilitates processing and forming.

[0057] Specifically, if the thickness h2 is too thin, the overlap heat fusion deformation during welding of the explosion-proof valve 20 will not play a role in positioning and assembling the explosion-proof valve 20. If it is too large, it will affect the assembly of the explosion-proof valve 20 and make it difficult to achieve a stable connection of the explosion-proof valve 20, thus reducing the strength of the connection structure of the explosion-proof valve 20.

[0058] In some specific implementation methods, such as Figure 4 As shown, the specific values ​​of the thickness h2 of the stepped surface of the stepped countersunk hole 111 in the axial direction of the explosion-proof hole 11 are: 0.5mm, 1.2mm, 1.8mm, 2.2mm, 3.0mm, 3.5mm, 4.0mm or 4.7mm.

[0059] In some embodiments, the circumferential width of the edge portion 23 of the explosion-proof valve 20 is 2mm ≤ w ≤ 10mm. The edge portion 23 is directly connected to the wall of the stepped countersunk hole 111. This embodiment limits the width of the edge portion 23 to facilitate welding and to give the welded explosion-proof valve 20 high structural strength.

[0060] Specifically, if the width of the edge portion 23 is too small, it will result in insufficient welding space during welding, causing the laser to hit the side wall of the explosion-proof valve 20, leading to explosion points, cracks, and other issues, thus reducing the yield and sealing performance. On the other hand, if the width of the edge portion 23 is too large, it will affect the overall stamping and forming process, and also waste layout space and materials.

[0061] A second aspect of the present invention provides a battery cell, the battery cell including any of the above-described battery cell cover assembly.

[0062] Specifically, the battery cell provided in this example has a battery cell cover assembly of any of the aforementioned embodiments. Therefore, the battery cell in this embodiment has the characteristic effects of each of the aforementioned battery cell cover assemblies. To avoid redundancy in the description of the effects, they will not be repeated here.

[0063] To verify the impact of various dimensional constraints on processing and forming, specific examples and proportions are provided below. Table 1 lists variables; all dimensions are the same except for those marked in the table.

[0064] Table 1:

[0065] As can be seen from Table 1, when a / h exceeds the upper limit, that is, when the thickness h of the explosion-proof valve 20 is too thin, the explosion-proof valve 20 will break as a whole during stamping, resulting in processing failure.

[0066] When a / h exceeds the lower limit, that is, when the thickness h of the explosion-proof valve 20 is too thick, the actual protrusion height a is small due to the excessive thickness of the explosion-proof valve 20. This results in the electrolyte being located at the bottom wall 21 of the explosion-proof valve 20, causing corrosion of the pressure relief guide groove 211 of the explosion-proof valve 20, failure of the opening pressure test, and premature detonation.

[0067] When b / a exceeds the lower limit, that is, when the position of the pressure relief guide groove 211 on the explosion-proof valve 20 is unbalanced with the height of the protrusion, the explosion-proof valve 20 detonates prematurely during the explosion test due to the large deviation between the position of the pressure relief guide groove 211 and the design position, and the opening pressure is unqualified.

[0068] In summary, the a / h ratio needs to be within a certain range. If the thickness h of the explosion-proof valve 20 is too small, it will affect the processing and forming, leading to forming failure. If it is too large, it will affect the protection of the electrolyte. The b / a ratio also needs to be within a certain range. If it is lower than the value, it indicates that the pressure relief guide groove 211 is too close to the edge, and stress and other issues may cause the explosion-proof valve 20 to fail.

[0069] Through the above description of the embodiments, those skilled in the art can clearly understand that in each embodiment, by setting the explosion-proof valve 20 as a protruding structure and the pressure relief guide groove 211 located on the bottom wall portion 21 in the inverted state of the battery cell, the explosion-proof valve 20 protrudes from the surface in the inner direction of the cover plate body 10, thereby preventing the electrolyte from contacting the bottom wall portion 21. Furthermore, during processing, the limitation of the ratio of the thickness of the explosion-proof valve 20 to the protrusion height facilitates the integral molding of the explosion-proof valve 20.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cell cover assembly, characterized in that, include: The cover plate body and the explosion-proof valve are provided. The cover plate body has an axially penetrating explosion-proof hole. One end of the explosion-proof hole has a stepped countersunk hole. The explosion-proof valve is fixedly connected in the stepped countersunk hole. The explosion-proof valve includes a bottom wall portion with a pressure relief guide groove and an annular side wall portion integrally formed with the bottom wall portion. The side wall portion has an edge portion extending along the outer side of the bottom wall portion integrally formed at one end away from the bottom wall portion. The edge portion is fixed to the inner wall of the stepped countersunk hole so that the bottom wall portion protrudes from the surface of the cover plate body on the side with the stepped countersunk hole. Wherein, the thickness of the explosion-proof valve is h, and in the thickness direction of the cover plate body, the distance between the bottom wall surface near the cover plate body and the step surface of the stepped platform is 0.9mm≤a≤18mm, and satisfies: 0.2≤a / h≤4.

2. The cell cover assembly according to claim 1, characterized in that, The side wall portion is inclined to the outside of the bottom wall portion, and the included angle between the side wall portion and the bottom wall portion 21 is 95°≤x≤130°.

3. The cell cover assembly according to claim 2, characterized in that, A first transition surface is formed between the sidewall portion and the bottom wall portion, and a second transition surface is formed between the sidewall portion and the edge portion. Both the first transition surface and the second transition surface are constructed as curved surfaces.

4. The cell cover assembly according to claim 1, characterized in that, The thickness of the cover plate body is 1mm≤h1≤5mm, and the thickness of the explosion-proof valve is 2mm≤h≤10mm.

5. The cell cover assembly according to claim 4, characterized in that, The step height of the stepped countersunk hole surface is consistent with the thickness of the explosion-proof valve.

6. The cell cover assembly according to claim 1, characterized in that, The pressure relief guide groove is provided with a scoring groove. The distance between the junction of the bottom wall and the side wall and the center line of the scoring groove is 0.5mm≤b≤30mm; and satisfies: 0.5≤b / a≤5, where a is the distance between the surface of the bottom wall near the cover body and the step surface of the stepped platform in the thickness direction of the cover body.

7. The cell cover assembly according to claim 1, characterized in that, In the circumferential direction of the explosion-proof hole, the extension width of the stepped countersunk hole surface is 0.2mm≤e≤20mm.

8. The cell cover assembly according to claim 1, characterized in that, The thickness of the stepped countersunk hole surface in the axial direction of the explosion-proof hole is 0.5mm≤h2≤4.7mm.

9. The cell cover assembly according to claim 1, characterized in that, In the circumferential direction of the explosion-proof valve, the extension width of the edge portion is 2mm≤w≤10mm.

10. A battery cell, characterized in that, The battery cell includes the battery cell cover assembly as described in any one of claims 1-9.

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