Positive collector plate and cylindrical lithium battery

Abstract

The positive collector plate comprises a plate body and a tail body which are connected with each other, the plate body is used for being connected with a roll core pole group, and the tail body is used for being connected with a battery cap, so that a passage is formed between the roll core pole group and the battery cap; the shape of the disc body is an axisymmetric figure formed by sequentially connecting a first edge, an arc and a second edge. The first edge and the second edge are connected with one end of the tail body; a circular center hole is formed in the center of the disc body, and at least one circular peripheral hole is formed in the periphery of the center hole; the sum of the areas of all the peripheral holes is 0.9-1.5 times of the area of the central hole; at least one groove is formed in the tail body; the tail body has an overall sectional area S at the position, except for the groove, of the tail body; at the position of the groove, the tail body has the minimum sectional area Sn, and the minimum sectional area Sn is 45%-65% of the overall sectional area S. The plate body and the tail body of the positive collector plate are improved, so that the balance between the mechanical strength and the seepage performance of the positive collector plate is realized, and the safety of the battery is ensured. The utility model also provides a cylindrical lithium battery.

Description

Technical Field

[0001] The present application relates to the technical field of lithium-ion batteries, and in particular to a positive electrode current collector and a cylindrical lithium battery. Background Art

[0002] According to the packaging form, lithium batteries can be divided into three forms: square, cylindrical and soft pack. Among them, cylindrical lithium batteries have gradually become a hot spot in lithium battery research due to their good consistency, high production efficiency, and strong heat dissipation capacity at the system level. Cylindrical batteries are usually packaged in cylindrical steel shells. The bare cell is made by winding process to form a cylindrical core electrode group. The cap is located on the top of the battery and is connected to the positive electrode in the core electrode group through the positive electrode collector.

[0003] The existing positive collector disc for cylindrical lithium batteries consists of a disc body and a tail body, wherein the disc body is used to connect with the winding core electrode group, and the tail body is connected with the cap after bending. The existence of the disc body will hinder the penetration efficiency of the electrolyte. Generally, holes can be opened on the periphery of the disc body to improve the penetration effect of the electrolyte, but the peripheral openings may be blocked by the rubber package, resulting in limited improvement effect. In addition, since the battery cell of the cylindrical lithium battery is prone to fire and explosion when short-circuited, the tail body of the positive collector disc of the existing cylindrical lithium battery is generally designed to be wide in width in order to have better conduction performance and facilitate connection with the cap, and lacks short-circuit protection. In order to have better short-circuit protection function, a fuse zone can be set at the tail body of the positive collector disc, but if the size of the fuse zone is not designed reasonably, on the one hand, it will reduce the mechanical strength of the tail body of the collector disc and increase the risk of the tail body breaking during the production process; on the other hand, the fuse zone may also have adverse effects such as uncontrollable fuse current and uncontrollable fuse position, which is not conducive to the rapid passage of electrons, increases the internal resistance of the battery, and affects the normal use of the battery.

[0004] Therefore, how to ensure that the positive electrode current collector has appropriate strength, has better electrolyte penetration effect, and can also achieve better short-circuit protection function is a problem that needs to be solved urgently. Utility Model Content

[0005] In order to solve the above problems, achieve a balance between the mechanical strength and liquid permeability of the positive current collector disk, and ensure battery safety, the first aspect of the present application provides a positive current collector disk, including a disk body 1 and a tail body 2 connected to each other, the disk body 1 is used to connect to the core electrode group 3, and the tail body 2 is used to connect to the battery cap, so that a passage is formed between the core electrode group 3 and the battery cap; the shape of the disk body 1 is an axially symmetrical figure composed of a first side 11, an arc 12 and a second side 13 connected in sequence; the first side 11 and the second side 13 are both connected to one end of the tail body 2; a circular center hole 14 is provided at the center of the disk body 1, and at least one circular peripheral hole 15 is provided on the periphery of the center hole 14; the sum of the areas of all the peripheral holes 15 is 0.9-1.5 times the area of ​​the center hole 14; at least one groove 22 is provided on the tail body 2; at a position on the tail body 2 other than the groove 22, the tail body 2 has an overall cross-sectional area S; at the position of the groove 22, the tail body 2 has a minimum cross-sectional area Sn, and the minimum cross-sectional area Sn is 45%-65% of the overall cross-sectional area S. The central hole 14 and the peripheral holes 15 of the disc body 1 provide a permeation channel for the electrolyte, improve the infiltration efficiency of the electrolyte, and ensure that the disc body 1 has a sufficient weldable area. By reasonably setting the minimum cross-sectional area range of the groove 22, the tail body 2 and the battery cap can be welded smoothly, improving the mechanical strength of the tail body 2, and ensuring that the current is cut off when the battery is thermally runaway.

[0006] In some optional embodiments, the area of ​​a single peripheral hole 15 is 0.3-0.5 times the area of ​​the central hole 14; the distance L between the center position of the groove 22 and the end of the tail body 2 away from the disc body 1 4 is the length L of the tail body 2 3 By further limiting the area relationship between the central hole 14 and the peripheral holes 15, it is ensured that the central hole 14 and the peripheral holes 15 can both play a corresponding penetration improvement effect, while retaining a larger weldable area. The position of the groove 22 on the tail body 2 makes the fuse position predictable, and the battery safety is improved.

[0007] In some optional embodiments, the diameter d of the peripheral hole 15 is 5 The diameter d of the center hole 14 3 50%-70%; at positions other than the groove 22 on the tail body 2, the tail body 2 has a first width L 2 At the position of the groove 22, the tail body 2 has a second width L 5 , and 3L 2 / 8≤L 5 <3L 2 / 4. By rationally designing the diameter parameters of the peripheral hole 15, the weldable area is retained on the one hand, and the electrolyte infiltration effect is improved on the other hand. By rationally designing the width of the tail body 2 at the groove 22, the mechanical properties of the tail body 2 and the safety performance of the battery are balanced, the risk of the tail body 2 breaking is reduced, and the yield rate is improved.

[0008] In some optional embodiments, the distance L between the center of the peripheral hole 15 and the center of the central hole 14 is 1 is the diameter d of the disk 1 1 By designing the spacing between the central hole 14 and the peripheral holes 15, the electrolyte infiltration efficiency is improved, and the subsequent encapsulation process to block the peripheral holes 15 is avoided.

[0009] In some optional embodiments, the diameter d of the central hole 14 is 3 The diameter d of the winding core hole 31 of the winding core electrode group 3 4 1.4-1.8 times; the dimension L of the groove 22 along the length direction of the tail body 2 7 0<L 7 ≤L 2 .

[0010] In some optional embodiments, the diameter d of the central hole 14 is 3 The diameter d of the disk 1 1 25%-35% of the tail body 2; the length L 3 is the diameter d of the disk 1 1 The reasonable diameter range of the center hole 14 firstly ensures that the plate 1 has a sufficient weldable area, while also improving the injection efficiency and reducing potential risks in the production process. By rationally designing the length of the tail body 2, it helps to balance the production efficiency and safety performance of the battery.

[0011] In some optional embodiments, the first side 11 and the second side 13 respectively form two symmetrical connection angles 5 with the two vertical sides 21 of the tail body 2, and the size of the connection angle 5 is 45°-90°; the diameter d of the disc body 1 1 is the diameter d of the winding core pole group 3 2 The design of the connection angle 5 facilitates the bending of the tail body 2, and a reasonable angle range helps to balance the mechanical properties of the collector plate and the size of the weldable area of ​​the plate body.

[0012] In some optional embodiments, the disc body 1 has a center angle A, and 40°≤∠A≤60°; wherein the center angle A takes the center of the arc 12 as the vertex, and the two sides pass through the end point of the first side 11 away from the arc 12 and the end point of the second side 13 away from the arc 12; the first width L of the tail body 2 2 =d1 *sin(∠B / 2), and 20°≤∠B≤40°; ∠B takes the center of the arc 1 as the vertex, and the two sides pass through the intersection of the straight line where the two vertical sides 21 are located and the full circle where the arc 12 is located. The design of the center angle A ensures that the plate body 1 still has a weldable area of ​​more than 75% after the hole is opened. The first width L of the tail body 2 2 Firstly, it ensures that the tail body 2 has sufficient mechanical strength to prevent it from being broken during the production process. At the same time, it is conducive to the rapid passage of electrons, reduces the internal resistance of the battery, and can retain the weldable area on the disc body 1 to the greatest extent.

[0013] The second aspect of the present application provides a cylindrical lithium battery, including a core electrode group 3 and a battery cap, wherein the positive electrode of the core electrode group 3 forms a passage with the battery cap through the above-mentioned positive electrode collector disk; wherein the disk body 1 is connected to the core electrode group 3, and the tail body 2 is connected to the battery cap. Since the positive electrode collector disk has the beneficial effects as described above, the cylindrical lithium battery provided by the present application has higher production efficiency and yield rate, and is highly safe. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0015] Figure 1 This is a schematic diagram of the structure of a positive electrode current collector disk according to an embodiment of the present application;

[0016] Figure 2 This is a schematic diagram of assembling a positive electrode current collecting disk in a cylindrical lithium battery according to an embodiment of the present application;

[0017] Figure 3 is a front view of a positive electrode current collecting disk according to an embodiment of the present application;

[0018] Figure 4 This is a top view of the assembly of a positive electrode current collector in a cylindrical lithium battery according to an embodiment of the present application;

[0019] Figure 5 This is a cross-sectional view of an assembly of a positive electrode current collector in a cylindrical lithium battery according to an embodiment of the present application;

[0020] Figure 6 It is a schematic diagram of the disk structure of a positive electrode current collector disk in one embodiment of the present application;

[0021] Figure 7 It is a schematic diagram of the tail structure of a positive electrode current collector disk according to an embodiment of the present application;

[0022] Figure 8 This application Figure 3 Cross-sectional view at section AA'.

[0023] Reference numerals: 1-disk body, 11-first side, 12-arc, 13-second side, 14-center hole, 15-peripheral hole, 2-tail body, 21-vertical side, 22-groove, 3-core electrode group, 31-core hole, 4-battery steel shell, 5-connection angle, d 1 - Diameter of the disk, d 2 - Core pole group diameter, d 3 -Center hole diameter, d 4 - Core hole diameter, d 5 -Diameter of the peripheral hole, L 1 - The distance between the center of the peripheral hole and the center of the central hole, L 2 - The first width of the tail body, L 3 - Tail length, L 4 - The distance between the center of the groove and the end of the tail body away from the disc body, L 5 - The second width of the tail body at the groove, L 6 -Thickness of tail body, L 7 - The dimension of the groove along the length of the tail body. DETAILED DESCRIPTION

[0024] Embodiments of the present embodiment are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment, and should not be construed as limiting the present embodiment.

[0025] In the description of this embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this embodiment.

[0026] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0027] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this embodiment based on the specific content of the technical solution.

[0028] Please refer to Figure 1 and Figure 2 , Figure 1 A schematic diagram of the structure of a positive electrode current collector disk according to an embodiment of the present application is shown. Figure 2 The schematic diagram of assembling a positive electrode collector disk in a cylindrical lithium battery according to an embodiment of the present application is shown. The positive electrode collector disk includes a disk body 1 and a tail body 2 connected to each other, wherein the disk body 1 is used to connect to the core electrode group 3, and the tail body 2 is used to connect to the battery cap (not shown) so as to form a passage between the core electrode group 3 and the battery cap. In the present application, the connection between the disk body 1 and the core electrode group 3, and the connection between the tail body 2 and the battery cap can adopt any connection method well known to those skilled in the art, such as welding; the connection between the tail body 2 and the disk body 1 can be any fixed connection method, and in order to ensure the stability of the connection and the overall strength of the collector disk, it is preferably an integral connection.

[0029] Please refer to Figure 3 , Figure 3 The front view of a positive electrode current collector disk of an embodiment of the present application is shown. In order to match the circular cross-section of the core electrode group 3 and facilitate welding between the disk body 1 and the core electrode group 3, the disk body 1 is preferably shaped as an axially symmetrical figure composed of a first side 11, an arc 12, and a second side 13 connected in sequence. Its shape can be considered as the shape remaining after the full circle (shown as a dashed line-dot dot) where the arc 12 is located is cut off two angles symmetrical about a diameter, and can also be considered as a shape similar to an arch. It should be noted that since the disk body 1 and the tail body 2 are connected, there is no connection between the first side 11 and the second side 13.

[0030] In order to improve the efficiency of injecting electrolyte during the battery production process, the disc 1 usually has holes for the electrolyte to pass through. In order to ensure that the physical area of ​​the disc 1 after drilling can still account for more than 75% of the total area of ​​the disc 1, so as to facilitate welding with the winding core electrode group 3, the disc 1 preferably has a center angle A, and 40°≤∠A≤60°, and further preferably 45°≤∠A≤55°. Specifically, the total area of ​​the above-mentioned disc 1 is the sum of the physical area of ​​the disc 1 and the hole area; the center angle A takes the center of the circle corresponding to the arc 12 as the vertex, and the two sides pass through the end point of the first side 11 away from the arc 12 and the end point of the second side 13 away from the arc 12 respectively. It can be understood that the end point of the first side 11 away from the arc 12 and the end point of the second side 13 away from the arc 12 are also the connection points of the first side 11, the second side 13 and the tail body 2.

[0031] See also Figure 4-6In some embodiments, the diameter d of the disk body 1 is 1 is the diameter d of the winding core pole group 3 2 80%-95%, wherein the diameter d of the disk body 1 1 It refers to the longest line segment between two points on the arc 12, and the diameter d of the winding core pole group 3 2 Refers to the diameter of the circular cross section of the winding core pole group 3. According to actual needs, the diameter d of the disk body 1 1 The size is, for example, 15-23 mm. The disk body 1 ensures a larger contact area between the disk body 1 and the winding core pole group 3 within the preferred diameter range, increases the weldable area, and expands the adaptability range of the welding wire length and shape.

[0032] In some embodiments, a center hole 14 is provided at the center of the disk body 1 for injecting electrolyte into the battery. The center of the disk body 1 may be the center of the circle corresponding to the arc 12. The winding core electrode group 3 of the cylindrical lithium battery is made by a winding process. After winding, a circular winding core hole 31 is formed at the center of the winding core electrode group 3. To match the shape of the winding core hole 31, the center hole 14 is preferably a circular hole.

[0033] In some embodiments, at least one peripheral hole 15 is provided on the periphery of the central hole 14 to assist in the infiltration of the electrolyte. Preferably, the peripheral hole 15 is a circular hole. Further preferably, the area of ​​a single peripheral hole 15 is 0.3-0.5 times the area of ​​the central hole 14, and the sum of the areas of all the peripheral holes 15 is 0.9-1.5 times the area of ​​the central hole 14. If the area of ​​the peripheral hole 15 is too small compared to the area of ​​the central hole 14, the auxiliary infiltration effect will not be obvious; if the area of ​​the peripheral hole 15 is too large, the weldable area of ​​the disk body 1 will be greatly reduced, affecting the connection between the disk body 1 and the winding core pole group 3. It can be understood that the areas of the peripheral holes 15 and the central hole 14 can be calculated according to the area formula of the circle, for example, the area S of the central hole 14 中心孔 =π(d 3 / 2) 2 .

[0034] In some embodiments, the diameter d of the central hole 14 is 3 The diameter d of the winding hole of the winding core pole group 4 Furthermore, the diameter d of the center hole 14 is 1.4-1.8 times of 3 The diameter d of the disk 1 1 According to actual needs, the diameter d of the center hole 14 is 3 The size is, for example, 4-8 mm. Within this diameter range, the center hole 14 can achieve a balance between the injection efficiency and the weldable area while ensuring the safety of welding. 3If the diameter d of the center hole 14 is too small, it will be unfavorable for the infiltration of the injection liquid, and when the resistance welding process is used at the bottom of the battery, the electrode head extending into the winding hole 31 of the winding electrode group 3 may produce an undesirable contact with the collector plate, which may cause interference risk. 3 If it is too large, the weldable area will be reduced accordingly, limiting the welding process between the disk body 1 and the winding core pole group 3 .

[0035] In some embodiments, the distance L between the center of the peripheral hole 15 and the center of the central hole 14 is 1 The diameter d of the disk 1 1 25%-35%. According to actual needs, L 1 For example, it is 4.5-7 mm. By properly designing the distance L between the peripheral hole 15 and the central hole 14 1 , which helps to improve the wetting effect of the electrolyte while ensuring the area of ​​the weldable area. 1 If the distance L between the peripheral hole 15 and the central hole 14 is too small, the electrolyte infiltration effect cannot be significantly improved; 1 If it is too large, the peripheral hole 15 is too close to the edge of the disk body 1 , thereby limiting the battery pack. If the packing blocks the peripheral hole 15 , the electrolyte cannot be injected through the peripheral hole 15 .

[0036] In order to facilitate processing and improve yield, in a preferred embodiment, the diameter d of the peripheral hole 15 is 5 The diameter of the center hole 14 is d 3 50%-70% of the diameter d of the peripheral hole 15 5 For example, it is 2-4.8 mm. If the diameter d of the peripheral hole 15 is 5 If the diameter d of the peripheral hole 15 is smaller than the preferred diameter range, it is difficult to achieve the auxiliary infiltration effect. 5 If the diameter is larger than the preferred range, the weldable area of ​​the disc body 1 is reduced. It can be understood that the number of peripheral holes 15 can be determined according to the actual welding process, the number of welding areas is n, and the number of peripheral holes 15 is n-1, wherein n≥2.

[0037] In order to facilitate bending and welding, the tail body 2 is usually in a long strip shape. Figure 7 In some embodiments, the tail body 2 has a first width L 2 =d 1 *sin(∠B / 2), and 20°≤∠B≤40°, preferably 25°≤∠B≤35°, wherein ∠B has the center of the arc 12 as the vertex, and the two sides pass through the intersection of the straight line where the two vertical sides 21 of the tail body 2 are located and the full circle where the arc 12 is located (see Figure 3 ). In the present application, the first width L of the tail body 2 2This means that the tail body 2 is regarded as a complete long strip, that is, the width of each position along the length direction is consistent, and this width is used as the first width L of the tail body 2. 2 The first width L of the tail body 2 2 The larger the width, the smaller the weldable area of ​​the disc body 1. Reasonable width design helps to retain the largest weldable area while ensuring that the tail body 2 has sufficient mechanical strength to prevent it from being broken during the production process. It is also beneficial for the rapid passage of electrons and reduces the internal resistance of the battery.

[0038] In actual assembly, the tail body 2 needs to be bent twice to connect with the battery cap. The first bend is to bend the tail body 2 away from the winding core electrode group 3, that is, Figure 2 In the state shown, the tail body 2 is upward, and the end away from the plate body 1 is exposed to the upper edge of the battery steel shell 4; the second bending is the tail body 2 bending away from the battery steel shell 4, and then connected to the battery cap. In order to ensure that the tail body 2 has a sufficient welding length, in some embodiments, the length L of the tail body 2 3 The diameter d of the disk 1 1 85%-95% of the tail body 2 length L 3 The length L of the tail body 2 is the distance between the end of the tail body 2 connected to the disc body 1 and the end of the tail body 2 away from the disc body 1. 3 For example, the length of the tail body 2 is 12-20 mm. The tail body 2 can be smoothly welded with the battery cap and ensure the safety of the battery within the preferred length range. 3 If the length of the tail body 2 is too short, the tail body 2 will not be long enough to extend out of the battery steel shell 4 after the first bend, and the welding with the battery cap cannot be completed. 3 If it is too long, the end of the tail body 2 away from the disc body 1 will contact the battery steel shell 4 during the second bending, causing a short circuit in the battery.

[0039] In some embodiments, the first side 11 and the second side 13 of the disc body 1 respectively form two symmetrical connection angles 5 with the two vertical sides 21 of the tail body 2. Compared with the scheme of connecting the tail body 2 to the arc 12, connecting the tail body 2 between the first side 11 and the second side 13 can be closer to the center of the disc body 1, so as to increase the distance between the tail body 2 and the battery steel shell 4 in the radial direction of the cylindrical battery after bending, and reduce the risk of short circuit. Preferably, the size of the connection angle 5 is 45°-90°; further preferably, the size of the connection angle 5 is 60°-80°. If the connection angle 5 is too small, the bending of the tail body 2 will cause the stress to be too concentrated at the connection angle 5, causing the disc body 1 to deform or even break; if the connection angle 5 is too large, it is impossible to ensure that the disc body 1 has sufficient weldable area. In addition, the reasonable angle design of the connection angle 5 also helps the electrolyte to penetrate into the battery through the connection angle 4.

[0040] In order to improve battery safety, in some embodiments, at least one groove 22 is provided on the tail body 2. The groove design reduces the width of the tail body 2 at the groove 22. When the battery is in thermal runaway, the current converges there, the heat rises and reaches the melting point, causing the tail body 2 to melt, thereby achieving the current cutting effect.

[0041] In some embodiments, the distance L between the center of the groove 22 and the end of the tail body 2 away from the disc body 1 is 4 is the length L of the tail body 2 3 Preferably, the distance L between the center position of the groove 22 and the end of the tail body 2 away from the disc body 1 4 is the length L of the tail body 2 3 According to actual needs, the distance L between the center position of the groove 22 and the end of the tail body 2 away from the disc body 1 4 For example, 8-18 mm. Figure 7 For example, the center of the trapezoidal groove shown in the figure is the intersection of the two diagonal lines of the trapezoid. The groove 22 is set at a reasonable position so that the tail body 2 and the battery cap can be welded smoothly, and at the same time, the current is cut off when the battery is thermally runaway. 4 If the distance is too small, the groove 22 will be too close to the welding position, and the welding of the tail body 2 and the battery cap will be interfered; on the contrary, the groove 22 is closer to the disk body 1, and the current path at the groove 22 is larger. If overcurrent occurs, it cannot be blown in time, increasing the safety risk of the battery.

[0042] In some embodiments, the tail body 2 has a second width L at the groove 22. 5 , and 3L 2 / 8≤L 5 <3L 2 / 4. The second width L in this application 5 That is, due to the design of the groove 22, the width of the tail body 2 is increased relative to the first width L 2 Based on the change of the second width L 5 Definition, the first width L in this application 2 Also referred to as the width of the tail body at a position other than the groove 22 on the tail body 2. The second width L of the tail body 2 at the groove 22 5 The mechanical performance of the tail body 2 and the safety performance of the battery can be balanced within a reasonable range. 5 If it is too small, the tail body 2 will be insufficiently strong at the groove 22 and will be easily broken when being bent.

[0043] Please refer to Figure 8 , Figure 8 Shows Figure 3In the cross-sectional view at the middle section AA', in some embodiments, the minimum cross-sectional area Sn of the tail body 2 at the groove 22 is 45%-65% of the overall cross-sectional area S of the tail body 2. Specifically, the minimum cross-sectional area Sn of the tail body 2 at the groove 22 is the cross-sectional area at the narrowest position of the groove 22, Sn = L 5 *L 6 The overall cross-sectional area S of the tail body 2 is the cross-sectional area of ​​the tail body 2 except the groove 22, S = L 2 *L 6 , L 6 is the thickness of the tail body 2. Within a reasonable range of the minimum cross-sectional area Sn, the tail body 2 can achieve a balance between battery safety and low internal resistance. When the minimum cross-sectional area Sn is too large, the tail body 2 cannot be quickly melted in the event of thermal runaway, increasing the safety risk; on the contrary, when the minimum cross-sectional area Sn is too small, on the one hand, the melting sensitivity will be too high, and on the other hand, the internal resistance will be increased, seriously affecting the normal use of the battery.

[0044] In some embodiments, the dimension L of the groove 22 along the length direction of the tail body 2 is 7 0<L 7 ≤L 2 , that is, the length of the groove 22 in the vertical direction does not exceed the first width L of the tail body 2 2 . Preferably, 1 / 4L 2 <L 7 ≤3 / 4L 2 In the present application, the dimension L of the groove 22 along the length direction of the tail body 2 is 7 It refers to the length between the end of the groove 22 closest to the disc body 1 and the end farthest from the disc body 1 (see Figure 7 ). The dimension L of the groove 22 along the length direction of the tail body 2 is 7 Within a reasonable range, it helps to improve the safety of the battery. 7 If L is too large, the fuse position of the tail body 2 is difficult to determine, thereby increasing the safety risk of the battery; on the contrary, if L 7 If it is too small, the fusing sensitivity of the tail body 2 will increase, and there is a possibility that it will be blown even under a safe current.

[0045] In order to enable the tail body 2 to reach the melting point at the groove 22 and be blown when the battery thermally runs away, the material of the current collecting plate is preferably aluminum.

[0046] The first aspect of the present application provides a positive electrode collector disk, which is suitable for cylindrical lithium batteries. By improving the disk body 1 and the tail body 2, the mechanical strength and liquid permeability of the positive electrode collector disk are balanced. The excellent mechanical strength avoids deformation, breakage and other phenomena during battery assembly, while the liquid permeability helps to improve production efficiency and reduce battery safety risks. In addition, the positive electrode collector disk of the present application also retains excellent welding performance, further reducing the process difficulty and improving the battery yield.

[0047] The second aspect of the present application provides a cylindrical lithium battery, including a core electrode group 3 and a battery cap, wherein the positive electrode of the core electrode group 3 forms a passage with the battery cap through the positive electrode collector disk as described above; wherein the disk body 1 is welded to the core electrode group 3, and the tail body 2 is welded to the battery cap. Since the positive electrode collector disk has the beneficial effects as described above, the cylindrical lithium battery provided by the present application has higher production efficiency and yield rate, and is highly safe.

[0048] In the description of this specification, reference to the terms "some embodiments", "an example", or similar descriptions means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment are included in at least one embodiment or example. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0049] Although examples of the present embodiment have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. A positive electrode current collector disk, comprising a disk body (1) and a tail body (2) connected to each other, wherein the disk body (1) is used to connect to a core electrode group (3), and the tail body (2) is used to connect to a battery cap, so that a passage is formed between the core electrode group (3) and the battery cap, characterized in that: The disk body (1) is in the shape of an axisymmetric figure consisting of a first side (11), an arc (12) and a second side (13) connected in sequence; the first side (11) and the second side (13) are both connected to one end of the tail body (2); A circular central hole (14) is arranged at the center of the disk body (1), and at least one circular peripheral hole (15) is arranged around the central hole (14); the sum of the areas of all the peripheral holes (15) is 0.9-1.5 times the area of ​​the central hole (14); At least one groove (22) is provided on the tail body (2); at positions on the tail body (2) other than the groove (22), the tail body (2) has an overall cross-sectional area S; at the position of the groove (22), the tail body (2) has a minimum cross-sectional area Sn, and the minimum cross-sectional area Sn is 45%-65% of the overall cross-sectional area S.

2. The positive electrode current collecting disk according to claim 1, characterized in that: The area of ​​a single peripheral hole (15) is 0.3-0.5 times the area of ​​the central hole (14); The distance L4 between the center position of the groove (22) and the end of the tail body (2) away from the disc body (1) is 60%-80% of the length L3 of the tail body (2).

3. The positive electrode current collecting disk according to claim 1, characterized in that: The diameter d5 of the peripheral hole (15) is 50%-70% of the diameter d3 of the central hole (14); At positions on the tail body (2) other than the groove (22), the tail body (2) has a first width L2; at positions of the groove (22), the tail body (2) has a second width L5, and 3L2 / 8≤L5<3L2 / 4.

4. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The distance L1 between the center of the peripheral hole (15) and the center of the central hole (14) is 25%-35% of the diameter d1 of the disk body (1).

5. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The diameter d3 of the central hole (14) is 1.4-1.8 times the diameter d4 of the winding core hole (31) of the winding core pole group (3); A dimension L7 of the groove (22) along the length direction of the tail body (2) is 0<L7≤L2.

6. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The diameter d3 of the central hole (14) is 25%-35% of the diameter d1 of the disk body (1); The length L3 of the tail body (2) is 85%-95% of the diameter d1 of the disk body (1).

7. The positive electrode current collecting disk according to any one of claims 1 to 3, characterized in that: The first side (11) and the second side (13) respectively form two bilaterally symmetrical connection angles (5) with the two vertical sides (21) of the tail body (2), and the size of the connection angle (5) is 45°-90°; The diameter d1 of the disk body (1) is 80%-95% of the diameter d2 of the winding core pole group (3).

8. The positive electrode current collector according to any one of claims 1 to 3, characterized in that: The disk body (1) has a center angle A, and 40°≤∠A≤60°; wherein the center angle A takes the center of the circle corresponding to the arc (12) as a vertex, and two sides respectively pass through the end point of the first side (11) away from the arc (12) and the end point of the second side (13) away from the arc (12); The first width L2 of the tail body (2) is d1*sin(∠B / 2), and 20°≤∠B≤40°; the ∠B has the center point corresponding to the arc (12) as its vertex, and two sides pass through the intersection of the straight line where the two vertical sides (21) of the tail body (2) are located and the full circle where the arc (12) is located.

9. A cylindrical lithium battery, characterized in that: It comprises the positive electrode current collecting disk as described in any one of claims 1 to 8.

10. The cylindrical lithium battery according to claim 9, characterized in that: The invention comprises the wound electrode group (3) and the battery cap, wherein the positive electrode of the wound electrode group (3) forms a passage with the battery cap through the positive electrode current collecting disk as described in any one of claims 1 to 8; wherein the disk body (1) is connected to the wound electrode group (3), and the tail body (2) is connected to the battery cap.

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