A cylindrical battery insulation pad, cap, and battery

Abstract

The utility model provides a kind of cylindrical battery insulating pad, cap and battery, it is related to battery field.The utility model designs the annular side wall of insulating pad with vertical opening downward, and is provided with chamfer at side wall and body connecting place, and the lower end of side wall is set to the ring cone shape of outward inclination.The insulating pad obtained by the design can form wrapped protection to the gap between the edge of roll core and shell, reduce the local contact short-circuit hidden danger caused by slight deviation of roll core or shell deformation;Better adapt to the inner wall arc or step structure of cylindrical battery shell;Meanwhile, it can also avoid the cracking of insulating pad caused by excessive local stress during assembly, and can also improve the overall toughness of structure, prolong service life.

Description

Technical Field

[0001] This utility model relates to the field of battery technology, and more specifically, to a cylindrical battery insulating pad, a cap, and a battery. Background Technology

[0002] Lithium-ion batteries are a type of rechargeable battery that primarily relies on the movement of lithium ions between the positive and negative electrodes to function. Lithium-ion batteries are characterized by high energy density, high output voltage, low self-discharge, excellent cycle performance, and high charging efficiency. They are a pollution-free, green battery. Insulating pads are used in the production process of lithium-ion batteries; these are crucial components of the battery cell. The insulating pads have tab holes through which the positive tab extends. The insulating pads insulate the bent positive tab from the core, preventing short circuits.

[0003] Currently, insulating mats have the following defects:

[0004] (1) Incomplete insulation protection: Traditional insulation pads are mostly flat bodies with straight walls, which do not cover the gap between the core edge and the shell. When the core is slightly offset due to vibration or assembly error, local exposed areas are likely to appear, increasing the risk of short circuit.

[0005] (2) Poor assembly compatibility: The straight sidewall is in rigid contact with the inner wall of the battery casing. If there are slight dimensional errors or inner wall curvature in the casing, assembly interference is likely to occur, resulting in the positioning of the insulating pad offset or the sidewall being squeezed and deformed, which affects the overall assembly efficiency.

[0006] (3) The structure is easily damaged: there is no transition design at the connection between the body and the side wall, and there are obvious stress concentration points. During assembly, it is easily affected by compression or temperature difference, which can easily cause cracks or even breakage, reducing the insulation life.

[0007] Based on this, a novel device is proposed to solve the aforementioned problems. Utility Model Content

[0008] The purpose of this invention is to provide a cylindrical battery insulating pad, cap, and battery to solve the problems mentioned in the background art.

[0009] The embodiments of this utility model can be implemented as follows:

[0010] In a first aspect, this utility model provides a cylindrical battery insulating pad, which includes:

[0011] The annular body has a first surface and a second surface that are opposite each other along the axial direction and a through-hole pole post; the first surface abuts against the core; and an annular sidewall with an opening facing downward is provided perpendicularly around the edge of the annular body, and a chamfer is provided at the connection between the annular sidewall and the annular body.

[0012] The chamfer type is a right-angle chamfer; its tilt angle is 40°-60°; the chamfer height is 0.45~0.55 mm;

[0013] The thickness ratio of the annular body to the annular sidewall is 0.35-0.6:1;

[0014] The upper end of the annular sidewall is connected to the annular body, and its lower end is an annular cone shape. The end closer to the upper end is the small diameter end, and the end farther from the upper end is the large diameter end.

[0015] The ratio of the diameter of the pole hole to the diameter of the inner chamfer of the annular body is 0.62-0.78:1.

[0016] Secondly, this utility model provides a cap that includes the aforementioned insulating pad.

[0017] In some embodiments, the cap further includes a top cover, an orifice plate, an explosion-proof sheet, and a sealing ring; the top cover, the orifice plate, and the explosion-proof sheet are all disposed within the sealing ring;

[0018] The middle of the perforated plate is the weak part. The explosion-proof sheet has three stepped surfaces, and the lowest stepped surface is connected to the weak part of the perforated plate. The side of the weak part connected to the explosion-proof sheet has a first notch. The depth of the first notch is 75% to 90% of the thickness of the weak part, and the angle of the notch is 45° to 50°.

[0019] In some embodiments, a second notch is provided on the side of the intermediate step surface of the explosion-proof sheet away from the perforated plate. The notch depth accounts for 18% to 25% of the thickness of the intermediate step surface, and the angle of the second notch is 45° to 50°. The second notch is a non-closed curve with a central angle of 310° to 340°.

[0020] In some embodiments, the edge of the perforated plate protrudes towards the explosion-proof sheet, and the edge of the perforated plate is sealed to the explosion-proof sheet by the lower end of the insulating pad.

[0021] Thirdly, this utility model also provides a battery, which includes the above-mentioned insulating pad or cap, as well as a positive current collector, a winding core, a negative current collector and a shell;

[0022] The positive current collector, the core, and the negative current collector are sequentially connected and placed within the housing's containment space. The cap is electrically connected to the positive current collector and is placed on one end of the housing.

[0023] In some embodiments, the positive current collector includes a disk body and a tail body connected to each other;

[0024] The disc body is used to connect with the core, and the tail body is used to connect with the cap so that a passage is formed between the core and the cap; a circular central hole is provided in the center of the disc body, and at least one circular peripheral hole is provided around the central hole.

[0025] The tail of the positive current collector is divided into a first section and a second section along the axial direction; the length ratio of the disk body to the first and second sections is (1.5~1.7):(1.05~1.15):1.

[0026] In some embodiments, the ratio of the width of the first segment of the tail body to the diameter of the central hole of the disc body is (1.15-1.25):1; the ratio of the width of the first segment to the width of the second segment of the tail body is 1:(1.8~2.2).

[0027] The first and second sections are transitioned by a chamfer, with the chamfer angle being 30°-45°.

[0028] The two corners of the second segment, which are furthest from the first segment, are chamfered, and the chamfers are rounded.

[0029] In some embodiments, the core includes a positive electrode sheet, a negative electrode sheet, and a separator spaced between the positive electrode sheet and the negative electrode sheet;

[0030] The electrode includes a current collector and a coating on one side of the current collector. The coating has multiple grooves on the surface away from the current collector, and the groove depth at the beginning of the positive electrode is less than the groove depth at the end of the positive electrode.

[0031] In some embodiments, the width of the groove is A, the length of the groove is B, the length of the electrode is L, the width of the electrode is W, the effective coating area of ​​the coating on the electrode is S, and the number of grooves is N, which satisfies the following formula:

[0032] N×A×B / S =3.0%-5.0%, S<L×W.

[0033] The beneficial effects of the cylindrical battery insulating pad, cap, and battery provided in this embodiment of the utility model include:

[0034] This invention features an insulating pad with a downward-facing annular sidewall and a chamfer at the connection between the sidewall and the main body. The lower end of the sidewall is also designed as an outward-sloping annular cone. The annular sidewall vertically encircles the edge of the main body, forming a three-dimensional insulating band from the core surface to the shell. Combined with the outward-sloping annular cone, this completely covers the gap between the core edge and the inner wall of the shell. Even if the core experiences slight displacement due to vibration or assembly errors, the sidewall's protective wrapping prevents abnormal current flow, structurally eliminating the risk of localized short circuits. The outward-sloping design of the cone-shaped lower end provides a guiding and positioning function. During assembly, the larger diameter end contacts the inner wall of the shell first and automatically calibrates its position, reducing assembly interference caused by shell size errors or inner wall curvature. The stable connection between the vertical sidewall and the main body ensures the overall positioning accuracy of the insulating pad. The chamfered structure at the connection disperses assembly pressure, preventing deformation or cracking of the insulating pad due to rigid collisions, significantly improving assembly efficiency and yield. Furthermore, the chamfered design at the connection between the sidewall and the main body eliminates stress concentration points. Combined with the tapered ring structure, the insulating pad can disperse stress through structural deformation when subjected to internal battery pressure or temperature changes, avoiding cracking caused by excessive local stress. This design allows the insulating pad to withstand long-term temperature cycling and mechanical vibration, significantly improving structural stability and service life. Attached Figure Description

[0035] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the insulating pad provided in this embodiment;

[0037] Figure 2 This is a schematic diagram of the cross-section of the insulating pad provided in this embodiment;

[0038] Figure 3 This is a schematic diagram of the structure of part A of the insulating pad provided in this embodiment;

[0039] Figure 4 This is a top view of the insulating pad provided in this embodiment;

[0040] Figure 5 This is a cross-sectional view of the battery cap provided in this embodiment;

[0041] Figure 6 This is a schematic diagram of the structure of the positive electrode current collector of the battery provided in this embodiment;

[0042] Figure 7 This is a schematic diagram of the electrode structure provided in this embodiment.

[0043] Icons: 1-Insulating pad; 2-Cap; 21-Top cover; 22-Explosion-proof sheet; 23-Sealing ring; 24-Orifice plate; 3-Positive current collector; 31-Disc body; 32-Tail body; 33-Center hole; 34-Outer hole; 35-First section; 36-Second section; 4-Electrode plate. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. The components of the embodiments of this utility model described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0047] In the description of this utility model, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the utility model product is usually placed during use, they are only for the convenience of describing this utility model 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, and therefore should not be construed as a limitation of this utility model.

[0048] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0049] It should be noted that, where there is no conflict, the features in the embodiments of this utility model can be combined with each other.

[0050] Please refer to Figure 1 The insulating pad 1 provided by this utility model is used in cylindrical lithium batteries.

[0051] The insulating pad 1 of this utility model includes an annular body; the annular body has a first surface and a second surface that are opposite to each other along the axial direction and a through-hole pole post; the first surface abuts against the core; and an annular sidewall with an opening facing downward is provided vertically around the edge of the annular body, and a chamfer is provided at the connection between the annular sidewall and the annular body; the upper end of the annular sidewall is connected to the annular body, and its lower end is an annular cone shape, with the smaller diameter end near the upper end and the larger diameter end away from the upper end.

[0052] In some embodiments, the chamfer type is a right-angle chamfer. Setting a chamfer can eliminate stress concentration and prevent structural damage; if no chamfer is set, the right-angle transition between the two will form an obvious stress concentration point - when the insulating pad 1 is squeezed by the inner wall of the shell during assembly, or when the battery is subjected to temperature changes (thermal expansion and contraction) or core vibration impact during operation, stress will accumulate sharply at the right-angle corner, which can easily lead to crack initiation or even breakage.

[0053] like Figure 2-3 As shown, its tilt angle can be expressed as 180°-α; the height of the chamfer is 0.45~0.55 mm.

[0054] The chamfer angle is limited in this invention because the chamfer angle of the annular conical sidewall directly determines the "introduction slope" during assembly. If the angle is too small (insufficient outward expansion), the contact area between the large-diameter end of the sidewall and the inner wall of the casing is small, resulting in weak guiding effect and easy assembly jamming due to casing size errors. If the angle is too large (excessive outward expansion), it will excessively occupy the radial space of the battery, compress the volume of the winding core, and may even cause rigid interference with the casing. The chamfer height is limited to the above range because if the height is <0.45 mm, the transition area is too short, the smooth transition effect of the chamfer is insufficient, and there may still be local stress concentration points, leading to cracking after long-term use. If the height is >0.55 mm, the transition area is too long, increasing the axial thickness of the insulating pad 1, compressing the axial space inside the battery, and may even cause interference with the winding core or the end of the casing.

[0055] In some embodiments, the thickness ratio of the annular body to the annular sidewall is 0.35-0.6:1. If the thickness of the annular body is too thick, although it can improve the rigidity of the sidewall, the excessive thickness of the body will compress the core space, and the excessive rigidity cannot adapt to the deformation of the core, which is prone to causing local stress concentration. If the thickness of the annular body is too thin, although it can meet the flexibility requirements of the body, the rigidity of the sidewall is insufficient, which is prone to deformation during assembly or use, resulting in positioning misalignment and sealing failure.

[0056] like Figure 4As shown, the ratio of the diameter R2 of the electrode hole to the diameter R1 of the inner chamfer of the annular body is 0.62-0.78:1. In this invention, if R1 is too small (i.e., the R2:R1 ratio is too large, such as close to 1:1), the distance from the edge of the electrode hole to the chamfer starting point is too short, the material width of the chamfer area is insufficient, and stress concentration will be more significant; when the core expands or the temperature changes, this area is prone to microcracks due to excessive material stretching, reducing insulation life; if R1 is too large, although it can increase the material width, it will cause the overall size of the annular body to increase, encroaching on the axial or radial space inside the battery (especially for cylindrical batteries with extremely high dimensional accuracy requirements), indirectly reducing energy density.

[0057] The cylindrical battery insulating pad 1 in this utility model is made of materials including but not limited to polypropylene, which is a commonly used insulating pad 1 material in the field. It has the characteristics of being lightweight, chemically resistant, heat-resistant and having excellent mechanical properties. In addition, the insulating pad 1 material can also be other conventional insulating pad 1 materials, and this utility model does not limit it in this regard.

[0058] In use, the insulating pad 1 is usually placed between the perforated plate 24 and the explosion-proof sheet 22. Therefore, the insulating pad 1 can also be used as one of the components of the cap 2. Based on this, the present invention can also provide a cap 2, which includes the above-mentioned insulating pad 1, as well as a top cover 21, a perforated plate 24, an explosion-proof sheet 22, and a sealing ring 23.

[0059] The structure of cap 2 is as follows Figure 5 As shown, it includes a top cover 21, a perforated plate 24, an insulating pad 1, an explosion-proof sheet 22, and a sealing ring 23; the top cover 21, the perforated plate 24, the insulating pad 1, and the explosion-proof sheet 22 are all disposed within the sealing ring 23.

[0060] From the cross-sectional view, the cap 2 consists of a top cover 21, an explosion-proof sheet 22, an insulating pad 1, and an orifice plate 24 from top to bottom. The top cover 21 has a first stepped surface and a second stepped surface, with the second stepped surface connecting to the explosion-proof sheet 22. The explosion-proof sheet 22 has three progressively downward stepped surfaces, with its lowest stepped surface connecting to the middle position of the orifice plate 24 to form a current cutting-off mechanism. The two are connected by laser welding.

[0061] Specifically, the middle position of the perforated plate 24 is a weak point. A first notch is provided on the weak point where it connects to the lowest step surface of the explosion-proof plate 22. The depth of the first notch is 75% to 90% of the thickness of the weak point, and the angle of the notch is 45° to 50°. In this invention, the first notch is a power-off protection notch. Through the above design, the gap between the explosion-proof plate 22 and the perforated plate 24 further facilitates the explosion-proof plate 22 in disconnecting the weak point from the perforated plate 24.

[0062] The thickness of the lowest step surface of the explosion-proof plate 22 is greater than that of the middle step surface and the highest step surface. The connection between the explosion-proof plate 22 and the perforated plate 24 is thickened and protruded. This protrusion is set to correspond to the weak part so that the protrusion can drive the weak part to disconnect from the perforated plate 24.

[0063] The explosion-proof disc 22 has a second notch on the side of the intermediate step surface away from the orifice plate 24. The depth of this notch is 18% to 25% of the thickness of the intermediate step surface, and the angle of the second notch is 45° to 50°. The second notch is a non-closed curve with a central angle of 310° to 340°. The second notch is designed here because when the internal pressure rises to the design burst pressure, the notch area will reach the material yield strength first due to stress concentration, thus opening the valve and preventing an explosion.

[0064] The highest step surface of the explosion-proof plate 22 connects with the second step surface of the top cover 21. The edge of the explosion-proof plate 22 is bent, and its height does not exceed the second step surface of the top cover 21, partially enclosing the edge of the top cover 21 through the edge of the explosion-proof plate 22. This partial enclosing design prevents the edge of the second step surface of the top cover 21 from directly contacting the sealing ring 23, thus preventing the sealing ring 23 from being punctured during compression. At the same time, setting the first step surface of the top cover 21 as an edgeless structure reduces the peripheral height dimension of the first step surface and lowers the overall peripheral height of the cap 2 assembly. This design simplifies the manufacturing process and the assembly process of the top cover 21.

[0065] The perforated plate 24 has vents at a position opposite to the middle stepped surface of the explosion-proof sheet 22. The purpose of this is to achieve controllable pressure relief under specific conditions and prevent the battery from exploding due to internal pressure accumulation.

[0066] The edge of the perforated plate 24 is designed to protrude in the direction of the explosion-proof sheet 22, and the edge of the perforated plate 24 is sealed to the explosion-proof sheet 22 through the lower end of the insulating pad 1. The insulating pad 1 here can improve the insulation effect between the perforated plate 24 and the explosion-proof sheet 22. By sealing the perforated plate 24 and the explosion-proof sheet 22 with the insulating pad 1, not only can the sealing effect be guaranteed, but the edge of the perforated plate 24 can also be supported. At the same time, it can ensure the stable connection between the explosion-proof sheet 22 and the perforated plate 24 by increasing the gap between them.

[0067] The sealing ring 23 has an L-shaped cross-section, with a limiting part on its surface and a buffer part below. The second step surface of the top cover 21 and the highest step surface of the explosion-proof sheet 22 are confined between the limiting part and the buffer part, thus achieving both limiting of the top cover 21 and the explosion-proof sheet 22 and a sealing effect. To further ensure the sealing effect, adhesive can be applied to the second step surface of the top cover 21 and the bottom of the bent edge of the explosion-proof sheet 22.

[0068] In this invention, the lower end of the sealing ring 23 does not exceed the lower end face of the perforated plate 24, with a preferred distance of 0.05~0.25 mm, to prevent damage to the electrode sheet 4 after the lower end is inserted into the electrode assembly after the core is packaged. The inner edge of the lower end of the sealing ring 23 has a tapered structure, which is used to prevent burrs from being generated by friction between the edge of the electrode assembly and the inner edge of the sealing ring, which could cause a short circuit and be detrimental to the safe use of the battery.

[0069] The above-described cap design achieves the following effect:

[0070] When the core fails and generates gas, the gas expands and compresses the explosion-proof sheet 22, causing the explosion-proof sheet 22 to bulge outward. Since the weak part on the perforated plate 24 is welded and fixed to the protrusion on the explosion-proof sheet 22, the protrusion will cause the weak part to bulge outward relative to the perforated plate 24, so that the weak part is disconnected from the perforated plate 24 or the three welding points used to connect the weak part and the explosion-proof valve are disconnected, thereby cutting off the power between the battery core and the external docking device and preventing the electrochemical reaction of the battery core from proceeding.

[0071] The aforementioned insulating pad 1 or cap 2 can be used in conjunction with other components to assemble a complete battery structure. Therefore, this utility model also provides a battery, which includes the aforementioned insulating pad 1 or cap 2, as well as a positive current collector 3, a core, a negative current collector, and a housing. The positive current collector 3, the core, and the negative current collector are sequentially connected and placed in the accommodating space of the housing. The cap 2 is electrically connected to the positive current collector 3 and is placed on one end of the housing.

[0072] In this utility model, the structure of the positive current collector 3 is as follows: Figure 6 As shown, it includes a disc body 31 and a tail body 32 connected to each other. The disc body 31 is used to connect with the core, and the tail body 32 is used to connect with the cap 2, so that a passage is formed between the core and the cap 2. The center of the disc body 31 is provided with a circular central hole 33, and at least one circular peripheral hole 34 is provided around the central hole 33.

[0073] Specifically, the tail body 32 of the positive electrode current collector 3 is divided into a first section 35 and a second section 36 along the axial direction; the length ratio of the disc body 31 to the first section 35 and the second section 36 is (1.5~1.7):(1.05~1.15):1. This design ensures that within the limited space of the battery casing, the core is as large as possible along the height direction of the casing, and the positive electrode current collector 3 can be bent into a "Z" shape.

[0074] The width ratio of the first segment 35 of the tail body to the diameter of the central hole 33 of the disc body 31 is (1.15-1.25):1; the width ratio of the first segment 35 to the second segment 36 of the tail body is 1:(1.8~2.2). The first segment 35 and the second segment 36 are transitioned by a chamfer, and the inclination angle of the chamfer is 30°-45°; more preferably, the inclination of the chamfer is lower, at 35°~40°, thereby increasing the welding area with the cap 2.

[0075] The two corners of the second segment 36, which is away from the first segment 35, are chamfered. The chamfer is a rounded chamfer, and the radius of the rounded chamfer can be set to 0.45~0.55 mm.

[0076] In some embodiments, the disk body 31 has multiple peripheral holes 34, all centered on the same annulus concentric with the central hole 33. The ratio of the radius (R1) of the peripheral holes 34 to the radius (R2) of the central hole 33 is 0.5 < R1 / R2 < 0.7. This ratio is specified to optimize electrolyte transfer efficiency and ensure uniform wetting and electrolyte injection stability of the electrode assembly. The central hole 33 serves as the main electrolyte injection channel, while the peripheral holes 34 assist in delivering electrolyte to the edge areas of the electrode assembly. This design achieves uniform electrolyte distribution across the entire electrode assembly, reducing cyclic degradation caused by localized electrolyte shortages.

[0077] In some embodiments, the ratio of the radius (R5) of the annulus containing the center of the peripheral hole 34 to the radius (R4) of the disk body 31 and the radius (R2) of the central hole 33 is R2:R5:R4 = 1:(2~2.1):(3.06~4.14). This specific ratio allows the conductive area of ​​the current collector around the peripheral hole 34 to directly contact the current collector in the active region of the electrode group, shortening the current conduction path from the active region of the electrode group to the current collector and reducing the contact resistance.

[0078] In some embodiments, the ratio of the minimum distance (L1) from the central hole 33 to any peripheral hole 34 to the minimum distance (L2) from any peripheral hole 34 to the edge of the disk 31 is: L1:L2=1:(0.9~1.1). Limiting the ratio to the above range can make the path length of current conduction from the peripheral hole 34 to the central hole 33 more uniform, reduce the phenomenon of excessive local current concentration, avoid the current surge due to the distance being too short in a certain area, or the conduction resistance increase due to the distance being too long, thereby reducing energy loss and the risk of local overheating, and improving the conductivity and safety of the battery.

[0079] In some embodiments, the disc body 31 is a circular structure with an arc-shaped notch, the notch being connected to the tail body. For example... Figure 6 As shown, the highest point of the arc-shaped notch is outside the circle where the center of the outer hole 34 is located, and it is connected to the tail body through an arc segment.

[0080] In some embodiments, the central angle of the arc at the connection between the disc body 31 and the first segment 35 is 50°~75°. This design prevents the disc body 31 and the tail body from tearing at this point when bending, and also makes the folding process of the tail body controllable, prevents the tail body from short-circuiting, and improves the safety performance of the core; it can also increase the welding area of ​​the disc body 31.

[0081] In this invention, the core includes a positive electrode 4, a negative electrode 4, and a separator spaced between the positive electrode 4 and the negative electrode 4; wherein, the electrode 4 (e.g., ...) Figure 7 (As shown) includes a current collector and a coating disposed on one side of the current collector. The coating has multiple grooves formed on the surface away from the current collector, and the groove depth at the beginning (i.e., inside the core) of the electrode 4 is less than the groove depth at the end (i.e., outside the core).

[0082] In some embodiments, the width of the groove is A, the length of the groove is B, the length of the electrode 4 is L, the width of the electrode 4 is W, the effective coating area of ​​the coating on the electrode 4 is S, and the number of grooves is N, which satisfies the following formula:

[0083] N×A×B / S =3.0%-5.0%, S<L×W.

[0084] The relationship between the length B of the groove and the width W of the electrode 4 is: B / W = 89.6%~99.2%, and the relationship between the width A of the groove and the distance C between the grooves is: A / C = 0.25~0.5.

[0085] Furthermore, the relationship between the groove length B and the width W of the electrode 4 is: 0 < WB ≤ 10 mm. Specifically, when 0 < WB ≤ 3 mm, no holes are formed in the overhang region, reducing edge lithium plating; when 3 mm ≤ WB ≤ 10 mm, no holes are formed in the thinning region, reducing active material loss. If W = B, i.e., a groove that completely penetrates the width, the electrode 4 has the greatest risk of strip breakage and cracking during winding, which may lead to a decrease in the edge structural strength of the electrode 4 or cause a short circuit risk. If WB is greater than 10 mm, it will reduce the wetting effect of the electrode 4.

[0086] Regarding the design of the groove, the greater the loss in mass / volume / area, the lower the mechanical strength of the wound electrode 4, making it more prone to cracking and breakage; conversely, insufficient loss results in a poorer expected performance improvement. This invention discovers that under the above conditions, the obtained electrode 4 can balance the problems of easy cracking and poor performance improvement.

[0087] In some implementations, the groove width needs to exceed the tab solder mark width by 0.5-1.0 mm; the distance between the groove edge and the edge of the electrode 4 needs to be ≥5 mm, so as to prevent the electrode 4 from tearing or short-circuiting.

[0088] In some embodiments, the bottom of the groove is arc-shaped or prismatic to facilitate processing and allow the electrolyte to enter the groove for wetting.

[0089] In some implementations, the ratio of the groove depth H to the coating thickness J is 0.1 to 0.7. Research has shown that if the groove is too deep, it may disrupt the longitudinal heat conduction channels of the electrode 4, weakening the overall heat dissipation capacity of the battery. Especially in high-speed charge-discharge scenarios, heat is difficult to effectively dissipate through the tabs, leading to a decrease in cycle life. The groove depth needs to be designed in coordination with the coating thickness of the electrode 4. A coating thickness that is too thin or too thick will affect the active material loading and lithium-ion diffusion path. If the groove depth is not adapted to the coating thickness, it may lead to excessive compression or uneven distribution of the active material in local areas, reducing the effective capacity. An improperly deep groove may alter the internal electronic conduction network of the electrode 4: when the depth is too shallow, the contact area between the conductive agent and the active material is insufficient, increasing the interface resistance; when the depth is too deep, it weakens the bonding strength between the current collector and the active material, causing an increase in contact resistance.

[0090] In some implementations, the depth of the groove is less than 50% of the total thickness of the electrode 4 (i.e., the thickness of the current collector layer + coating). If it exceeds 50%, the bending resistance of the electrode 4 will decrease significantly, and it will be prone to breakage during the stacking or winding process, which will increase the risk of micro-short circuit inside the battery.

[0091] The electrode 4 obtained through the above design can ensure its structural strength while having a good wetting effect.

[0092] Based on the design of the above-mentioned insulating pad 1, cap 2, positive electrode current collector 3 and electrode 4, this utility model can obtain a battery with higher safety, longer cycle life and better electrochemical performance.

[0093] The above description is only a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model.

Claims

1. A cylindrical battery insulating pad, characterized in that, include: An annular body; the annular body has a first surface and a second surface that are axially opposed and a through-hole; The first surface abuts against the core; and the annular sidewall with an opening facing downward is vertically provided on the edge surrounding the annular body, and a chamfer is provided at the connection between the annular sidewall and the annular body; The chamfer type is a right-angle chamfer; its tilt angle is 40°-60°. The height of the chamfer is 0.45~0.55 mm; The thickness ratio of the annular body to the annular sidewall is 0.35-0.6:1; The upper end of the annular sidewall is connected to the annular body, and its lower end is an annular cone shape, with the smaller diameter end closer to the upper end and the larger diameter end further away from the upper end. The ratio of the diameter of the pole hole to the diameter of the inner chamfer of the annular body is 0.62-0.78:

1.

2. A cap, characterized in that, Includes the insulating pad as described in claim 1.

3. The cap according to claim 2, characterized in that, The cap also includes a top cover, a perforated plate, an explosion-proof sheet, and a sealing ring; the top cover, the perforated plate, and the explosion-proof sheet are all disposed within the sealing ring; The middle of the perforated plate is a weak part, and the explosion-proof sheet has a three-level stepped surface, with the lowest step surface connected to the weak part of the perforated plate; a first groove is provided on the side of the weak part connected to the explosion-proof sheet, the depth of the first groove is 75% to 90% of the thickness of the weak part, and the angle of the groove is 45° to 50°.

4. The cap according to claim 3, characterized in that, The explosion-proof sheet has a second groove on the side of the middle step surface away from the perforated plate. The depth of the groove is 18% to 25% of the thickness of the middle step surface, and the angle of the second groove is 45° to 50°. The second etch mark is a non-closed curve with a central angle of 310°~340°.

5. The cap according to claim 4, characterized in that, The insulating pad is disposed between the perforated plate and the explosion-proof sheet. The edge of the perforated plate protrudes towards the explosion-proof sheet, and the lower end of the insulating pad seals the edge of the perforated plate and the explosion-proof sheet together.

6. A battery, characterized in that, Includes the insulating pad as described in claim 1 or the cap as described in any one of claims 2-5, as well as the positive current collector, the core, the negative current collector, and the housing; The positive current collector, the core, and the negative current collector are sequentially connected and placed within the housing's accommodating space. The cap is electrically connected to the positive current collector and is placed over one end of the housing.

7. The battery according to claim 6, characterized in that, The positive current collector includes a disk body and a tail body that are connected to each other; The disc body is used to connect with the winding core, and the tail body is used to connect with the cap, so as to form a passage between the winding core and the cap; a circular central hole is provided at the center of the disc body, and at least one circular peripheral hole is provided around the central hole; The tail of the positive current collector is divided into a first segment and a second segment along the axial direction; the length ratio of the disk body to the first segment and the second segment is (1.5~1.7):(1.05~1.15):

1.

8. The battery according to claim 7, characterized in that, The ratio of the width of the first segment of the tail body to the diameter of the central hole of the disc body is (1.15-1.25):1; the ratio of the width of the first segment to the width of the second segment of the tail body is 1:(1.8~2.2). The first and second segments are connected by a chamfer, with the chamfer angle being 30°-45°. The second segment has chamfers at the two corners of the end furthest from the first segment, and the chamfers are rounded chamfers.

9. The battery according to claim 6, characterized in that, The core includes a positive electrode sheet, a negative electrode sheet, and a separator spaced between the positive electrode sheet and the negative electrode sheet; The electrode includes a current collector and a coating on one side of the current collector. The coating has multiple grooves on the surface away from the current collector, and the groove depth at the beginning of the positive electrode is less than the groove depth at the end of the positive electrode.

10. The battery according to claim 9, characterized in that, The groove has a width of A, a length of B, a length of L, a width of W, an effective coating area of ​​S on the electrode, and a number of N grooves, satisfying the following formula: N×A×B / S =3.0%-5.0%, S<L×W.

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