Cover plate assembly and battery cell

Abstract

The invention relates to the technical field of lithium batteries, and provides a cover plate assembly and a battery cell, the cover plate assembly comprises a cover plate body, lower plastic, an electrode and a turnover part, and the cover plate body is provided with a mounting hole; the lower plastic is arranged on one side of the cover plate body, a through hole is formed in the lower plastic corresponding to the mounting hole, and a thickening part is arranged on the lower plastic adjacent to the through hole; the electrode is arranged on one side, deviating from the cover plate body, of the lower plastic and partially penetrates through the through hole and the mounting hole; the folding part is connected with the thickening part, and the folding part is suitable for being folded relative to the thickening part so as to be attached to the side, away from the cover plate body, of the electrode. According to the cover plate assembly, the folding part and the thickening part are arranged to be matched with the electrode structure, the mechanical strength is improved, meanwhile, the contact area with the electrode group is increased to improve heat dissipation, the battery cell capacity is improved by optimizing the space layout, and the cover plate assembly has the advantages that the mechanical strength is improved, the heat dissipation effect is improved, and the battery cell capacity and the fixing effect are improved.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, and more particularly to cover plate assemblies and battery cells. Background Technology

[0002] Lithium-ion batteries are widely used in various fields such as transportation power supplies, power storage, new energy storage power supplies, and aerospace and military industries due to their advantages such as large capacity, high operating voltage, strong charge retention, and long cycle life. The battery cell is the smallest unit of a lithium battery pack. In existing technologies, the cell structure generally consists of an electrolyte, electrode assembly, bare cell insulating sheet, cover plate, shell, top adhesive patch, and outer insulating film. The shell and cover plate are welded together to form a closed space for accommodating the electrode assembly. The cover plate typically integrates functional areas such as electrodes, electrolyte injection holes, and explosion-proof valves. Inside the cell, to allow space for bending of the electrode assembly's tabs, the lower plastic portion of the cover plate is usually thickened, creating a gap between the electrode assembly and the cover plate. This results in a small direct contact area between the lower plastic and the electrode assembly, leading to poor electrode assembly fixation. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems existing in the related art. To this end, the present invention proposes a cover plate assembly designed to improve the fixation effect of the electrode assembly.

[0004] The present invention also proposes a battery cell.

[0005] According to a first aspect of the present invention, the cover plate assembly includes: The cover plate body is provided with mounting holes; The lower plastic is disposed on one side of the cover plate body, and the lower plastic has a through hole corresponding to the mounting hole, and the lower plastic has a thickened part adjacent to the through hole; An electrode is provided on the side of the lower plastic away from the cover plate body, and partially passes through the through hole and the mounting hole; A folded portion, which is connected to the thickened portion, is adapted to fold relative to the thickened portion to fit against the side of the electrode opposite to the cover plate body.

[0006] According to the cover plate assembly of the present invention, by providing a folded portion and a thickened portion to cooperate with the electrode structure, the mechanical strength is improved while the contact area with the electrode group is increased to improve heat dissipation. Furthermore, the battery cell capacity is improved by optimizing the spatial layout. The assembly has the advantages of improving mechanical strength, improving heat dissipation, increasing battery cell capacity, and improving fixation.

[0007] According to one embodiment of the present invention, the electrode includes a main body, a welding part, and a connecting section connected together. The connecting section connects the main body and the welding part respectively. The connecting section is set at an angle to the main body and the welding part. The main body is fitted with the folded part. The welding part is used for welding to the electrode lug of the electrode assembly. When the folded part is fitted to the side of the electrode away from the cover plate body, in a direction parallel to the cover plate body, the distance between the end of the folded part away from the thickened part and the connecting section is W, and satisfies: 3mm≤W≤5mm.

[0008] According to one embodiment of the present invention, a folding notch is provided at the connection between the folded portion and the thickened portion.

[0009] According to one embodiment of the present invention, when the folded portion is perpendicular to the thickened portion, the depth of the folded notch is T2, and the thickness of the folded portion is T1, which satisfies: 1mm≤T1≤2mm, 0.4≤(T1-T2) / T1≤0.6.

[0010] According to one embodiment of the present invention, the distance between the end of the folded portion away from the thickened portion and the thickened portion is defined as the length of the folded portion, the length of the folded portion is H1, and when the folded portion is perpendicular to the thickened portion, the height of the folded notch is H2, which satisfies: 0.06≤H2 / H1≤0.1.

[0011] According to one embodiment of the present invention, the width of the folded portion is W1, which satisfies: 10(T1-T2) / W1≥0.1.

[0012] According to one embodiment of the present invention, the cover plate body is bent to form a boss, and the boss is arranged to protrude toward the side opposite to the lower plastic.

[0013] According to one embodiment of the present invention, the cover plate body is provided with two protrusions, and the two protrusions are spaced apart in the length direction of the cover plate body.

[0014] According to one embodiment of the present invention, the cover plate assembly further includes an explosion-proof valve, which is disposed on the cover plate body and located between the two bosses.

[0015] According to a second aspect of the present invention, the battery cell includes: A housing having an open cavity structure; A pole assembly, wherein the pole assembly is disposed within the cavity structure; The aforementioned cover assembly is connected to the pole group and covers the opening of the cavity structure.

[0016] The battery cell according to an embodiment of the present invention includes the above-described cover plate assembly, and therefore has all the technical effects of the above-described cover plate assembly, which will not be repeated here.

[0017] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the front structure of the cover plate assembly provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the back structure of the cover plate assembly provided in an embodiment of the present invention.

[0021] Figure 3 This is a schematic diagram of the back of the cover plate assembly provided in an embodiment of the present invention, wherein the folding part is in a flipped-up state.

[0022] Figure 4 This is a front view of the cover plate assembly provided in an embodiment of the present invention, wherein the folding portion is in a folded-down state.

[0023] Figure 5 This is a front view of the cover plate assembly provided in an embodiment of the present invention, wherein the folding portion is in a flipped-up state.

[0024] Figure 6 yes Figure 5 A schematic diagram showing the dimensions of the folded section.

[0025] Figure 7 This is a structural schematic diagram of the assembly process of the cover plate assembly and the electrode group provided in the embodiment of the present invention.

[0026] Figure 8 This is a top view of the assembly process of the cover plate assembly and the pole group provided in the embodiment of the present invention.

[0027] Figure 9 This is a schematic diagram of the structure of the cover plate assembly and the electrode assembly after assembly according to an embodiment of the present invention.

[0028] Figure 10 This is a cross-sectional view of the cover plate assembly and pole group after assembly according to an embodiment of the present invention.

[0029] Figure 11 yes Figure 10 A magnified view of a portion of point A in the middle.

[0030] Figure label: 2. Cover plate assembly; 21. Cover plate body; 211. Boss; 212. Explosion-proof valve; 22. Lower plastic; 221. Thickened part; 222. Folding part; 223. Folding notch; 23. Electrode; 231. Main body; 232. Welding part; 233. Connecting section; 3. Electrode group; 31. Electrode lug; 311. Weld mark. Detailed Implementation

[0031] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0032] 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 convenience of describing 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.

[0033] 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 based on the specific circumstances.

[0034] 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," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply 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 that the first feature is at a lower horizontal level than the second feature.

[0035] 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.

[0036] In existing technologies, lithium-ion battery cell covers generally suffer from insufficient mechanical strength, low heat dissipation efficiency, and limited space utilization. While the cover provides basic support after welding to the casing, the area around the two electrodes 23 lacks an effective load-bearing structure, making them susceptible to deformation and short-circuit risks from external impacts. The space required for bending the tabs 31 occupies internal cell height, reducing capacity density. Simultaneously, the limited contact area between the lower plastic 22 and the electrode assembly 3 results in poor fixation. Heat dissipation in the cover area between the two electrodes 23 relies primarily on thermal radiation, and heat accumulation negatively impacts battery performance stability.

[0037] Therefore, as Figures 1 to 5 As shown, this application proposes a cover plate assembly 2 including a cover plate body 21, a lower plastic 22, an electrode 23, and a folding portion 222. The cover plate body 21 is provided with mounting holes; the lower plastic 22 is disposed on one side of the cover plate body 21, with a through hole corresponding to the mounting hole and a thickened portion 221 formed in the vicinity; the electrode 23 passes through the through hole and the mounting hole and is disposed on the back side of the lower plastic 22; the thickened portion 221 is connected to the foldable folding portion 222, which can be attached to the back side of the electrode 23 to form a support, and the side of the folding portion 222 facing away from the electrode 23 can be attached to the electrode assembly 3 (i.e., the electrode assembly), thereby improving the fixing effect between the cover plate assembly 2 and the electrode assembly 3.

[0038] It should be noted that the cover plate assembly 2 includes a positive electrode and a negative electrode, which are symmetrically arranged at both ends of the cover plate body 21. Correspondingly, the lower plastic 22 is provided with two thickened parts 221 and two folded parts 222 for corresponding to the positive electrode and the negative electrode. Here, we take one electrode 23 as an example. The other electrode 23 can have the same or different structure as the corresponding electrode 23. This is not limited here.

[0039] Understandably, the mounting hole refers to the positioning structure penetrating the cover plate body 21, used to precisely fix the position of the electrode 23. The lower plastic 22 refers to a support component made of insulating material, which can be combined with the cover plate body 21 using injection molding. Its through-hole is coaxial with the mounting hole to ensure the installation accuracy of the electrode 23. The thickened portion 221 refers to a locally thickened area of ​​the lower plastic 22, which can be achieved by adjusting the wall thickness during molding. It is used to enhance structural strength and support the end face of the electrode assembly 3, thus creating a gap between part of the cover plate body 21 and the electrode assembly 3. The electrode 23 refers to a conductive metal component, with the main body 231 passing through the through-hole for electrical connection. The folded portion 222 refers to a flexible structure connected to the thickened portion 221, which, after folding, forms a covering support for the back of the electrode 23.

[0040] For example, the cover plate body 21 serves as the basic load-bearing structure, forming a mechanical connection with the electrode 23 through mounting holes. The thickened portion 221 of the lower plastic 22 forms a reinforcing area around the mounting position of the electrode 23. During assembly, after the electrode 23 is positioned and installed through the through holes, the operator bends the folded portion 222 downwards until it completely adheres to the back of the electrode 23. At this time, the folded portion 222 and the thickened portion 221 together form a support system, which not only disperses the external force applied to the electrode 23, but also improves the stability of the electrode 23 by increasing the contact area. After the folded portion 222 adheres to the back of the electrode 23, it forms a continuous heat-conducting surface with the cover plate body 21, improving the heat dissipation efficiency in the area between the two electrodes 23.

[0041] Through the above technical solutions, this application effectively improves the overall mechanical strength of the cover plate assembly 2 and reduces the risk of short circuits caused by the deformation of the electrode 23 under stress. The optimized spatial layout increases the internal utilization rate of the cell, allowing more electrode material to be accommodated in the same volume. The combined design of the folded portion 222 and the thickened portion 221 enhances the fixing effect on the electrode group 3, while establishing a more efficient heat dissipation path and improving the battery's operational stability. This structure achieves a simultaneous improvement in cell energy density and safety performance while ensuring assembly reliability.

[0042] like Figure 4 As shown, this application further proposes that the electrode 23 includes a main body portion 231, a welding portion 232, and a connecting section 233 connected together. The connecting section 233 connects the main body portion 231 and the welding portion 232 respectively. The connecting section 233 is set at an angle to the main body portion 231, and the connecting section 233 is set at an angle to the welding portion 232. The main body portion 231 is fitted with the folded portion 222. The welding portion 232 is used to weld to the electrode tab 31 of the electrode assembly 3. When the folded portion 222 is fitted to the side of the electrode 23 away from the cover plate body 21, in the direction parallel to the cover plate body 21, the distance between the end of the folded portion 222 away from the thickened portion 221 and the connecting section 233 is 3 mm to 5 mm. Please refer to the reference. Figures 7 to 11The thickened portion 221 and the folded portion 222 are used to abut against the end face of the electrode group 3. The welding portion 232 of the electrode 23 is used to weld to the tab 31 of the electrode group 3. On the projection plane parallel to the cover plate body 21, the area of ​​the tab 31 is S1, the total area of ​​the weld mark 311 formed by welding the electrode 23 and the tab 31 is S2, the end face area of ​​the electrode group 3 is S3, and the total area of ​​the thickened portion 221 and the folded portion 222 is S4, and the ratio of S2 / S1 is 11% to 18% and the ratio of S4 / S3 is 30% to 45%.

[0043] Understandably, the main body 231 refers to the support structure in electrode 23 that contacts the folded part 222; the welding part 232 refers to the extension structure in electrode 23 that connects to the tab 31, which can be formed into a thin sheet area through stamping to facilitate welding operations; the connecting section 233 refers to the inclined section of the transition area between the main body 231 and the welding part 232, which is convenient to adapt to the shape of the lower plastic 22; the S2 / S1 ratio refers to the ratio of the welding area to the total area of ​​the tab 31, which can be achieved by adjusting the number and distribution of welding points to balance connection strength and material loss; the S4 / S3 ratio refers to the ratio of the coverage area of ​​the thickened part 221 and the folded part 222 to the end face area of ​​the electrode assembly 3, which can be achieved by controlling the plastic volume distribution through molding to optimize the positioning and space utilization of the electrode assembly 3.

[0044] For example, after the main body 231 and the welding part 232 form a stepped structure, the folding part 222 covers the electrode 23 along the extension direction of the main body 231 in the folded state. The connecting section 233 serves as a physical limiting reference to ensure that the contact area between the welding part 232 and the electrode tab 31 is always in a predetermined position. When the end of the folding part 222 and the connecting section 233 maintain a distance of 3 mm to 5 mm, it can avoid the folding action from interfering with the welding area and maintain the covering and protection function of the folding part 222 on the electrode 23. By controlling the S2 / S1 ratio in the range of 11% to 18%, the solder joint density can form a continuous conductive path without causing thermal damage to the electrode tab 31 due to excessive welding. At the same time, by controlling the S4 / S3 ratio in the range of 30% to 45%, the lower plastic 22 structure can maximize the contact with the end face of the electrode group 3 within a limited projected area, thereby improving the fixing stability through surface contact and reducing the redundant space between the electrode group 3 and the cover plate.

[0045] Through the above technical solution, this application solves the connection failure problem caused by welding positioning deviation between electrode 23 and tab 31. The composite support structure formed by the thickened part 221 and the folded part 222 enhances the axial fixing ability of the electrode group 3. At the same time, by optimizing the projection area ratio, the ineffective space inside the cell is reduced while ensuring structural strength, thereby increasing the amount of active material filled per unit volume.

[0046] Please refer to the reference. Figure 5 and Figure 6This application further proposes a technical solution that involves creating a folding notch 223 at the connection between the folded portion 222 and the thickened portion 221, with the folded portion 222 and the thickened portion 221 forming an integral structure, thereby limiting the welding penetration range and welding tensile strength threshold of the electrode tab 31. Please refer to the reference. Figure 7 and Figure 8 For example, the welding penetration depth of the tab 31 satisfies a minimum penetration depth of 100 μm and a maximum penetration depth of 60% of the thickness of the tab 31. Optionally, the welding pull force F between the electrode 23 and the tab 31 satisfies: F ≥ 50 N.

[0047] Understandably, the folding notch 223 refers to a locally thinned area formed at the joint, which can be achieved through mechanical cutting or molding processes. It guides the folding action and reduces stress concentration. The one-piece molding structure refers to manufacturing the folded portion 222 and the thickened portion 221 as a single continuous body using injection molding, eliminating the risk of interface separation caused by separate connections. The weld penetration range refers to the depth to which the tab 31 is melted through during welding, forming a gradient metallurgical bonding layer and avoiding excessive material damage. The weld tensile strength threshold refers to the minimum standard at which the weld point can withstand axial tensile force, which can be verified using tensile testing equipment to ensure the weld point has anti-pull-out capability.

[0048] For example, a notch structure is provided at the connection between the folded portion 222 and the thickened portion 221, so that material deformation during the folding process is concentrated in the notch area, thereby preventing cracks from forming at the connection root due to stress concentration. The one-piece molding process forms a continuous body with no interface transition between the folded portion 222 and the thickened portion 221, avoiding abrupt stress changes due to material differences when subjected to vibration or impact loads. Figure 8 As shown, for the welding process of tab 31, by controlling the penetration depth to within 60% of the thickness of tab 31, both effective metallurgical bonding at the weld interface is ensured, and excessive penetration is avoided, which would reduce the mechanical strength of tab 31. The setting of the welding tensile strength threshold, from a mechanical performance perspective, mandates that the weld joint has the ability to resist tensile loads generated during assembly or use.

[0049] Through the above technical solution, this application effectively improves the fatigue resistance at the connection between the folded part 222 and the thickened part 221, eliminates defects such as false welding or over-melting at the welding interface, and ensures the long-term stability of the connection between the electrode 23 and the tab 31, thereby reducing the risk of short circuit caused by structural failure of the battery cell.

[0050] like Figure 6 As shown, this application further proposes that when the folded portion 222 is perpendicular to the thickened portion 221, the depth of the folded notch 223 is T2 and the thickness of the folded portion 222 is T1, which satisfies: 1mm≤T1≤2mm, 0.4≤(T1-T2) / T1≤0.6.

[0051] Understandably, the folding notch 223 refers to the groove structure opened at the connection between the folded portion 222 and the thickened portion 221. It can be implemented using stamping or injection molding processes, and its function is to guide the folded portion 222 to bend along a predetermined path. The thickness T1 of the folded portion 222 refers to the material thickness perpendicular to the folding direction, and its function is to provide sufficient bending stiffness to withstand external loads. The ratio (T1-T2) / T1 is used to characterize the relative relationship between the notch depth and the material thickness, and its function is to balance the stress distribution in the root region of the folded portion 222.

[0052] For example, the folding notch 223 forms a stress concentration area by locally thinning the material, so that the folding action is concentrated at the notch. When T1 is controlled between 1mm and 2mm, the material has both the rigidity to resist deformation and avoids excessive folding resistance due to excessive thickness. The ratio of 0.4 to 0.6 ensures that the notch depth is sufficient to guide bending deformation, while retaining sufficient root material thickness to prevent breakage. During the folding process, the notch preferentially undergoes elastic deformation, allowing the folded part 222 to conform to the surface of the electrode 23 at a controllable angle, avoiding plastic deformation or crack propagation due to stress concentration.

[0053] Through the above technical solutions, this application resolves the risk of fracture in the folding section 222 caused by unreasonable structural design, ensuring the reliability and repeatability of the folding action. The synergistic effect of the folding notch 223 and its thickness ratio allows the folding section 222 to maintain structural integrity under assembly pressure, while reducing the external force required for bending operations. The optimized design of the root region effectively suppresses stress concentration, preventing functional failure caused by material fatigue during long-term use.

[0054] Please continue to refer to Figure 6 This application further proposes that, when the folded portion 222 is perpendicular to the thickened portion 221, the ratio of the height of the folding notch 223 to the length of the folded portion 222 is limited, such that the ratio is between 0.06 and 0.1. For example, the distance between the end of the folded portion 222 furthest from the thickened portion 221 and the thickened portion 221 is defined as the length of the folded portion 222, and the length of the folded portion 222 is H1. When the folded portion 222 is perpendicular to the thickened portion 221, the height of the folding notch 223 is H2, which satisfies: 0.06 ≤ H2 / H1 ≤ 0.1.

[0055] Understandably, the length of the folded portion 222 refers to the straight-line distance between the end of the folded portion 222 furthest from the thickened portion 221 and the thickened portion 221. This parameter is used to quantify the extension range of the folded portion 222, ensuring its positioning accuracy in a vertical state. The height of the folding notch 223 refers to the vertical dimension of the notch extending along the length direction of the folded portion 222. The setting of the height of the folding notch 223 directly affects the smoothness of the folding action and the stress distribution at the connection point.

[0056] For example, by controlling the ratio between the height of the folding notch 223 and the length of the folded portion 222, an effective stress buffer zone can be formed in the area of ​​the folding notch 223 when the folded portion 222 is bent. When this ratio is at the lower limit, the depth of the folding notch 223 is sufficient to prevent the material from cracking due to stress concentration during bending; when it is at the upper limit, the size of the folding notch 223 will not excessively weaken the tensile strength of the connection. During assembly, the folded portion 222 can be stably bent along the weakening line formed by the notch, ensuring that the contact surface with the electrode 23 surface maintains a uniform pressure distribution after folding.

[0057] Through the above technical solution, this application effectively solves the problem of material damage caused by stress concentration during the folding action, while maintaining the mechanical integrity of the connection part. After bending, the folding part 222 can form a stable surface contact with the surface of the electrode 23, avoiding gaps caused by local deformation, thereby improving the sealing reliability of the internal structure of the battery cell.

[0058] Please refer to the reference. Figure 3 and Figure 6 Furthermore, this application proposes that the width of the folded part 222 is W1, which satisfies: 10(T1-T2) / W1≥0.1.

[0059] Understandably, the width of the folded portion 222 refers to the dimension of the folded portion 222 extending circumferentially along the electrode 23. This parameter affects the contact area between the folded portion 222 and the electrode 23, as well as its resistance to bending. The depth of the fold notch 223 refers to the thickness of the material removed at the connection between the folded portion 222 and the thickened portion 221. This parameter controls the stress distribution during bending. The thickness of the folded portion 222 refers to the material thickness in the area where the fold notch 223 is not provided. This parameter determines the deformation resistance of the folded portion 222.

[0060] For example, by establishing a relationship between the width of the folded portion 222 and structural parameters, a balance between mechanical performance and space occupancy is achieved during bending. When the depth of the folding notch 223 increases, resulting in a decrease in the remaining material thickness, the width of the folded portion 222 is constrained to decrease synchronously to avoid stress concentration during bending; when the depth of the folding notch 223 decreases, the width is allowed to increase appropriately to improve the contact stability with the electrode 23. This proportional relationship ensures that the folded portion 222 maintains sufficient fracture resistance during bending while avoiding compression of the electrode assembly 3 installation space due to excessive width.

[0061] Through the above technical solution, this application effectively solves the problem of decreased mechanical strength caused by structural parameter mismatch during the bending action of the folding part 222. Under the premise of ensuring structural stability, it optimizes the internal space layout of the cover plate assembly 2 and avoids the failure of electrode 23 fixation or cell capacity loss caused by the folding part 222 being too wide or too narrow.

[0062] Please refer to the reference. Figure 1 and Figure 9 This application further proposes to form a boss 211 by bending the cover plate body 21, with the boss 211 protruding towards the side opposite to the lower plastic 22.

[0063] Understandably, the boss 211 refers to a localized raised structure formed on the surface of the cover plate body 21 through a plastic deformation process. Specifically, it can be achieved using a stamping process, and its height can be adjusted according to actual assembly requirements. This structure creates a three-dimensional support structure by altering the planar shape of the cover plate, distributing the load to the edge area of ​​the boss 211 when subjected to external impact. This process maintains material continuity while forming a three-dimensional support structure, avoiding the risk of interface failure associated with welding or riveting additional components.

[0064] For example, when an external force is applied to the surface of the cover plate, the bending ridges of the boss 211 structure form multiple stress transmission paths, causing the impact load to be conducted along the sidewall of the boss 211 to the edge of the cover plate. The top surface of the boss 211 forms a surface contact with the external assembly structure. In terms of heat dissipation, the three-dimensional structure formed by the sidewall and top surface of the boss 211 increases the surface area in contact with the outside, and heat can be dissipated more quickly through the conduction path of the boss 211.

[0065] For example, the height of the boss 211 is higher than the height of the electrode 23 protruding from the surface of the cover plate body 21, meaning that the external device is supported on the boss 211 rather than the electrode 23. This application effectively reduces stress concentration in the electrode 23 area under external impact, preventing the risk of internal short circuits caused by electrode 23 deformation. The boss 211 structure enhances the overall bending stiffness of the cover plate, improving the structural stability of the battery cell under vibration or drop conditions. The increased heat dissipation surface area optimizes the heat conduction path, improving the uniformity of the battery cell's operating temperature. The assembly reference surface formed by the boss 211 improves the positioning accuracy of the battery cell and external modules, reducing secondary stress caused by assembly errors.

[0066] like Figure 1 As shown, this application further proposes to provide two protrusions 211 on the cover plate body 21, with the two protrusions 211 spaced apart in the length direction of the cover plate body 21.

[0067] Understandably, the cover plate body 21 refers to the main body 231 that constitutes the top closed structure of the battery cell. It is usually made of metal material by stamping and is used to support components such as the electrode 23 and the explosion-proof valve 212 and to achieve welding and sealing with the shell. The two protrusions 211 are spaced apart in the length direction, which means that two local raised structures separated along the long side are formed on the surface of the cover plate body 21 by stamping process. For example, symmetrical trapezoidal protrusions are formed by continuous molding process. The spaced distribution forms a symmetrical support structure, avoids stress concentration and optimizes the spatial layout.

[0068] For example, when the two bosses 211 are spaced apart along the length, the symmetrical distribution of the bosses 211 ensures that when the cover plate body 21 is subjected to external impact, the load is evenly transferred to the welding areas of the two side shells, reducing the risk of the electrode 23 being directly stressed. The intermediate area formed by the spaced arrangement can be used to integrate the explosion-proof valve 212 or the injection hole. For example, a recessed area can be formed between the two bosses 211 to install the explosion-proof valve 212, thereby achieving functional zoning within a limited space. The local reinforcement structure of the bosses 211 improves the bending strength of the cover plate body 21 while avoiding material waste due to overall thickening. Its spaced arrangement reserves more space at the top of the electrode group 3, for example, by reducing the gap height between the electrode group 3 and the cover plate, thereby increasing the effective volume of the electrode group 3.

[0069] Through the above technical solution, this application solves the short-circuit risk of electrode 23 caused by insufficient mechanical strength of the cover plate, and improves the overall structural stability of the cell by dispersing external loads through symmetrically distributed bosses 211. The spaced bosses 211 optimize the spatial layout of the cover plate surface, providing installation areas for components such as the explosion-proof valve 212. The local raised structure formed by the bosses 211 also increases the heat dissipation area of ​​the cover plate surface, improving the heat conduction efficiency in the area between the two electrodes 23.

[0070] This application further proposes that the cover plate assembly 2 also includes an explosion-proof valve 212, which is disposed on the cover plate body 21 and located between two bosses 211.

[0071] Understandably, the explosion-proof valve 212 is a safety device that releases pressure by rupturing when the internal pressure of the battery is abnormal. Specifically, it can be implemented by using a metal diaphragm with a grooved structure. Two protrusions 211 are arranged at intervals along the length of the cover plate body 21 to form a rigid support area.

[0072] For example, the explosion-proof valve 212 is constrained between the physical barriers formed by the two protrusions 211. When an external impact force acts on the surface of the cover plate, the protrusions 211 act as the first load-bearing structure to absorb and disperse mechanical stress, preventing the impact energy from being directly transmitted to the area of ​​the explosion-proof valve 212. During the thermal expansion process inside the battery, the three-dimensional support frame formed by the two protrusions 211 can suppress the deformation amplitude of the planar area of ​​the cover plate body 21, ensuring that the safe distance between the explosion-proof valve 212 and the electrode 23 remains constant. The tapered structure design of the protrusions 211 expands the bending space of the tab 31 in the vertical direction, while avoiding the formation of sharp edges on the surface of the cover plate that may affect assembly safety.

[0073] Through the above technical solution, this application effectively prevents the explosion-proof valve 212 from rupturing unexpectedly due to external impact, ensuring that the battery pressure relief function is triggered only under the set pressure threshold. The boss 211 structure, while improving the mechanical strength of the cover plate, optimizes the layout relationship between the bending space of the tab 31 and the area of ​​the explosion-proof valve 212. The coordinated arrangement of the explosion-proof valve 212 and the boss 211 forms a multi-layered protection mechanism, maintaining the structural integrity of the pressure relief channel in the event of battery thermal runaway.

[0074] This application further proposes a battery cell, including a housing, an electrode group 3, and a cover plate assembly 2. The housing forms an open cavity structure, the electrode group 3 is disposed within the cavity structure, and the cover plate assembly 2 is connected to the electrode group 3 and covers the opening of the housing.

[0075] Understandably, the housing refers to the enclosed structure used to accommodate the electrode assembly 3, providing a stable installation space for the electrode assembly 3 by forming a cavity structure. The electrode assembly 3 refers to the electrode assembly formed by winding or stacking positive and negative electrode sheets and a diaphragm. The cover plate assembly 2 refers to the integrated structure including the cover plate body 21, the lower plastic 22, the electrode 23, and the folded part 222. Specifically, it can be achieved by injection molding or welding processes, forming a seal by covering the opening of the housing, and simultaneously abutting against the end face of the electrode assembly 3 to enhance the fixing effect.

[0076] For example, the cavity structure formed by the housing optimizes the internal space layout, minimizing the gap between the electrode assembly 3 and the housing, thereby improving space utilization. After the cover plate assembly 2 is connected to the electrode assembly 3, the thickened portion 221 and the folded portion 222 of the lower plastic 22 directly contact the end face of the electrode assembly 3, forming a multi-point support structure and enhancing the overall rigidity of the cell. The conductive path formed by welding the electrode 23 to the tab 31 reduces resistance by increasing the contact area, while heat is conducted to the housing through the contact surface between the cover plate assembly 2 and the electrode assembly 3, achieving multi-path heat dissipation.

[0077] Through the above technical solutions, this application achieves the improvement of the overall mechanical strength of the battery cell, so that the impact of external force is dispersed and borne by the shell and cover plate assembly 2; improves the heat dissipation efficiency, so that heat is quickly discharged through the contact surface between the electrode group 3 and the cover plate assembly 2; and optimizes the internal space layout, thereby increasing the filling amount of electrode active material in the same volume, thereby increasing the battery cell capacity.

[0078] Please refer to the reference. Figure 3 , Figure 4 and Figure 6 To verify the effectiveness of the above scheme, different DOEs were used, and simulation analysis and cell safety testing were combined. The results are shown in Tables 1 and 2 below: Table 1 (Unit: mm)

[0079] As shown in Table 1, when the plastic design under the cover plate meets the above requirements, the strength of the folding part meets the requirements, and there are no abnormalities in folding. Understandably, in Comparative Example 1, (T1-T2) / T1 is less than 0.4; in Comparative Example 2, 10(T1-T2) / W1 is less than 0.1; and in Comparative Example 3, H2 / H1 is less than 0.06. In these cases, insufficient strength is likely to occur during folding, resulting in breakage at the notch or difficulty in folding.

[0080] Table 2 (Units are F or mm) 2 )

[0081] As shown in Table 2, when the plastic design under the cover plate meets the above requirements, the electrode assembly is well fixed, satisfying the design requirements of the battery cell and the entire package. Conversely, poor electrode assembly fixing can easily lead to electrode tab tearing. For example, in Comparative Example 1, when F is less than 50, in Comparative Example 2, S2 / S1 is less than 11%, and in Comparative Example 3, S4 / S3 is less than 30%, electrode tab tearing is more likely to occur.

[0082] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A cover plate assembly, characterized in that, include: The cover plate body is provided with mounting holes; The lower plastic is disposed on one side of the cover plate body, and the lower plastic has a through hole corresponding to the mounting hole, and the lower plastic has a thickened part adjacent to the through hole; An electrode is provided on the side of the lower plastic away from the cover plate body, and partially passes through the through hole and the mounting hole; A folded portion, which is connected to the thickened portion, is adapted to fold relative to the thickened portion to fit against the side of the electrode opposite to the cover plate body.

2. The cover plate assembly according to claim 1, characterized in that, The electrode includes a main body, a welding part, and a connecting section connected together. The connecting section connects the main body and the welding part respectively. The connecting section is set at an angle to the main body. The main body is fitted with the folded part. The welding part is used to weld to the electrode lug of the electrode assembly. When the folded part is fitted to the side of the electrode away from the cover plate body, in a direction parallel to the cover plate body, the distance between the end of the folded part away from the thickened part and the connecting section is W, and satisfies: 3mm≤W≤5mm.

3. The cover plate assembly according to claim 1, characterized in that, A folding notch is provided at the connection between the folded portion and the thickened portion.

4. The cover plate assembly according to claim 3, characterized in that, When the folded portion is perpendicular to the thickened portion, the depth of the folded notch is T2, and the thickness of the folded portion is T1, which satisfies: 1mm≤T1≤2mm, 0.4≤(T1-T2) / T1≤0.

6.

5. The cover plate assembly according to claim 4, characterized in that, The distance between the end of the folded portion away from the thickened portion and the thickened portion is defined as the length of the folded portion, and the length of the folded portion is H1. When the folded portion is perpendicular to the thickened portion, the height of the folded notch is H2, which satisfies: 0.06≤H2 / H1≤0.

1.

6. The cover plate assembly according to claim 5, characterized in that, The width of the folded part is W1, which satisfies: 10(T1-T2) / W1≥0.

1.

7. The cover plate assembly according to any one of claims 1 to 6, characterized in that, The cover plate body is bent to form a boss, and the boss is convex toward the side opposite to the lower plastic.

8. The cover plate assembly according to claim 7, characterized in that, The cover plate body is provided with two protrusions, which are spaced apart along the length of the cover plate body.

9. The cover plate assembly according to claim 8, characterized in that, The cover plate assembly also includes an explosion-proof valve, which is disposed on the cover plate body and located between the two protrusions.

10. A battery cell, characterized in that, include: A housing having an open cavity structure; A pole assembly, wherein the pole assembly is disposed within the cavity structure; The cover assembly as described in any one of claims 1 to 9, wherein the cover assembly is connected to the pole group and covers the opening of the cavity structure.

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