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 welded with a roll core pole group, and the tail body is used for being welded with a battery cap, so that a passage is formed between the roll core pole group and the battery cap; the tail body is provided with at least one groove, and the distance between the center position of the groove and the end, away from the disc body, of the tail body is 60%-80% of the length of 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 current cut-off design is improved, the position of the groove in the tail body and the minimum sectional area of the groove are reasonably arranged, so that the tail body and the battery cover cap can be smoothly welded, the mechanical strength of the tail body is improved, and meanwhile it is ensured that current cut-off is achieved when the battery is in thermal runaway.

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 to the winding core electrode group, and the tail body is used to connect to the battery cap. 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 wider in width in order to have better conduction performance and facilitate connection with the cap, and lacks short-circuit protection. In order to have a better short-circuit protection function, a fuse zone can be set at the tail body of the positive collector disc. However, if the position, size, etc. of the fuse zone are not designed reasonably, on the one hand, the mechanical strength of the tail body of the collector disc will be reduced, and the risk of the tail body breaking during the production process will be increased; on the other hand, the fuse zone may also have unfavorable effects such as uncontrollable fuse current and uncontrollable fuse position, which is not conducive to the rapid passage of electrons, so that the internal resistance of the battery increases, which will affect the normal use of the battery. Therefore, how to ensure that the positive collector disc has a suitable strength while achieving a better short-circuit protection function is a problem that needs to be solved urgently. Utility Model Content

[0004] In order to solve the above problems, the first aspect of the present application provides 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 with the winding core electrode group 4, and the tail body 2 is used to connect with the battery cap, so that a passage is formed between the winding core electrode group 4 and the battery cap; wherein at least one groove 3 is provided on the tail body 2, and the distance L1' between the center position of the groove 3 and the end of the tail body 2 away from the disk body 1 is 60%-80% of the length L1 of the tail body 2; at the position of the tail body 2 other than the groove 3, the tail body 2 has an overall cross-sectional area S; at the position of the groove 3, 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. By reasonably setting the position of the groove 3 on the tail body 2 and the minimum cross-sectional area range at the groove 3, the tail body 2 and the battery cap can be welded smoothly, the mechanical strength of the tail body 2 is improved, and at the same time, the current is cut off when the battery is thermally runaway.

[0005] In some optional embodiments, the tail body 2 has an overall width L at positions other than the groove 3 on the tail body 2; at the position of the groove 3, the tail body 2 has a variable diameter width Dn, and the variable diameter range of the variable diameter width Dn is 3L / 8≤Dn<3L / 4. By reasonably designing the variable diameter width of the tail body 2 at the groove 3, the mechanical properties of the tail body and the safety performance of the battery are balanced, the risk of tail body breakage is reduced, and the yield rate is improved.

[0006] In some optional embodiments, at positions other than the groove 3 on the tail body 2, the tail body 2 has an overall thickness D; at the position of the groove 3, the tail body 2 has a variable diameter thickness Dn', and the variable diameter range of the variable diameter thickness Dn' is D / 2<Dn'<D. Preferably, the variable diameter range of the variable diameter thickness Dn' is 0.1-0.3mm. By designing the thickness change at the groove, the current converges to a specific position, ensuring the fusing sensitivity of the tail body 2, and the fusing position is more controllable.

[0007] In some optional embodiments, the dimension Zn of the groove 3 along the length direction of the tail body 2 is 0<Zn≤L. By properly designing the dimension of the groove 3 along the length direction of the tail body 2 so that the fuse position is within a predictable range, the safety of the battery is improved.

[0008] In some optional embodiments, the shape of the disc body 1 is an axisymmetric 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. Through the shape design of the disc body 1 and the specific connection position of the disc body 1 and the tail body 2, it is ensured that the disc body 1 has a sufficient weldable area, and the distance between the tail body 2 and the battery steel shell after bending is increased, thereby improving the safety performance of the battery.

[0009] In some optional embodiments, at the connection between the disk body 1 and the tail body 2, the first edge 11 and the second edge 13 respectively form two left-right symmetrical connection angles 6 with the two vertical edges 21 of the tail body 2. The design of the connection angle 6 facilitates the bending of the tail body 2, which helps to balance the mechanical properties of the collecting disk and the size of the weldable area of ​​the disk body.

[0010] In some optional embodiments, the overall width L of the tail body 2 = d*sin(∠A / 2), where d is the diameter of the disk body 1; ∠A has the center of the circle corresponding to the arc 12 as the vertex, and the two sides pass through the intersection of the two vertical sides 21 of the tail body 2 and the full circle where the arc 12 is located, 20°≤∠A≤40°. The overall width L of the tail body 2 first ensures that the tail body has sufficient mechanical strength to prevent it from being broken during the production process, and at the same time facilitates the rapid passage of electrons, reduces the internal resistance of the battery, and can retain the weldable area on the disk body 1 to the greatest extent.

[0011] In some optional embodiments, the length L1 of the tail body 2 is 85%-95% of the diameter d of the disc body 1. By properly designing the length of the tail body 2, it is helpful to balance the production efficiency and safety performance of the battery.

[0012] The second aspect of the present application provides a cylindrical lithium battery, including a core electrode group 4 and a battery cap, wherein the positive electrode of the core electrode group 4 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 4, 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, and the battery has low internal resistance and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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.

[0014] 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;

[0015] 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;

[0016] Figure 3 is a front view of a positive electrode current collecting disk according to an embodiment of the present application;

[0017] Figure 4 It is a schematic diagram of the tail structure of a positive electrode current collector disk according to an embodiment of the present application;

[0018] Figure 5 It is a side view of the tail structure of a positive electrode current collector disk according to an embodiment of the present application;

[0019] Figure 6 This application Figure 3 Cross-sectional view at section BB';

[0020] 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;

[0021] Figure 8 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 markings: 1-disk body, 11-first side, 12-arc, 13-second side, 2-tail body, 21-vertical side, 3-groove, 4-core electrode group, 5-battery steel shell, 6-connection angle, d-disk body diameter, L-overall width of tail body, L1-tail body length, D-overall thickness of tail body, Dn-variable diameter width, L1'-distance between the center position of the groove and the end of the tail body away from the disk body, Dn'-variable diameter thickness, Zn-dimension of the groove along the length direction of the tail body. DETAILED DESCRIPTION

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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 2The 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 4, and the tail body 2 is used to connect to the battery cap (not shown) to form a passage between the core electrode group 4 and the battery cap. In the present application, the connection between the disk body 1 and the core electrode group 4, and the connection between the tail body 2 and the battery cap can be 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.

[0028] 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 4 and facilitate the connection between the disk body 1 and the core electrode group 4, 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 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 relationship between the first side 11 and the second side 13.

[0029] In some embodiments, the first side 11 and the second side 13 of the disk body 1 are both connected to one end of the tail body 2. In actual assembly, the tail body 2 needs to be bent twice, wherein the tail body 2 is bent in the direction away from the winding core electrode group 4 as a first bend, and the tail body 2 is bent in the direction away from the battery steel shell 5 as a second bend, and then connected to the battery cap. Since the disk body 1 has a bow-like shape, compared to connecting the tail body 2 on the arc 12, connecting the tail body 2 on two sides makes the tail body 2 closer to the center of the disk body 1, so as to increase the distance between the tail body 2 and the battery steel shell 5 in the radial direction of the cylindrical battery after bending, and reduce the risk of short circuit.

[0030] In some embodiments, at the connection between the tail body 2 and the disk body 1 , the first side 11 and the second side 13 of the disk body 1 respectively form two bilaterally symmetrical connection angles 6 with the two vertical sides 21 of the tail body 2 .

[0031] For the convenience of bending and welding, the tail body 2 is usually in the shape of a long strip. In some embodiments, the overall width L of the tail body 2 = d*sin(∠A / 2), where d is the diameter of the disk body 1, which refers to the longest line segment between two points on the arc 12. According to actual needs, the diameter of the disk body 1 is, for example, 15-23 mm; ∠A takes the center of the circle corresponding to the arc 12 as the vertex, and the two sides pass through the intersection of the two vertical sides 21 of the tail body 2 and the full circle where the arc 12 is located, 20°≤∠A≤40°, preferably 25°≤∠A≤35°. In the present application, the overall width L of the tail body 2 refers to treating the tail body 6 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 overall width of the tail body 2. The larger the overall width of the tail body 2, 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 conducive to the rapid passage of electrons and reduces the internal resistance of the battery.

[0032] Please refer to Figure 4 , Figure 4 A schematic diagram of the tail body structure of a positive electrode current collector disk of an embodiment of the present application is shown. In some embodiments, the length L1 of the tail body 2 is 85%-95% of the diameter d of the disk body 1. According to actual needs, the length of the tail body 2 is, for example, 12-20 mm. Within the above preferred length range, the tail body 2 can ensure smooth welding with the battery cap and ensure the safety of the battery. If the length of the tail body 2 is too short, the tail body 2 will not extend out of the battery steel shell after one bending, and the welding with the battery cap cannot be completed; if the length of the tail body 2 is too long, the end of the tail body 2 away from the disk body 1 will contact the battery shell when the battery cap cover is bent for the second time, causing the battery to short-circuit.

[0033] In some embodiments, at least one groove 3 is formed on the tail body 2. The groove design reduces the width of the tail body 2 at the groove 3. 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. Specifically, the shape of the groove 3 can be a trapezoid (see Figure 4 ), rectangular, U-shaped, V-shaped (seen in Figure 7 ), semicircular (seen in Figure 8 ) and other arbitrary shapes. The present application does not limit the number of grooves 3, and multiple figures exemplarily show two symmetrically arranged grooves 3. When there are multiple grooves 3, all grooves 3 can be of the same shape or of different shapes. In principle, the arrangement of the grooves 3 must ensure both the fusing effect and the mechanical strength of the tail body 2.

[0034] In some embodiments, the distance L1' between the center position of the groove 3 and the end of the tail body 2 away from the disk body 1 is 60%-80%, and more preferably 68%-78% of the length L1 of the tail body 2. According to actual needs, the distance between the center position of the groove 3 and the end of the tail body 2 away from the disk body 1 is, for example, 8-18 mm. If the shape of the groove 3 is a simple figure, the center position of the groove 3 can be a position recognized by those skilled in the art, such as a trapezoidal or rectangular groove 3, the center position of which can be the intersection of two diagonals; and for a semicircular groove 3, the center position can be the center of the circle. If the shape of the groove 3 is more complex or irregular, the center position of the groove 3 is the geometric center of its shape, that is, the average position of all points in the shape, which can be determined by any method known to those skilled in the art, such as integral method, discrete point method, graphic segmentation method, etc., or directly calculated using software tools. The length L1 of the tail body 2 is the distance between the connection between the tail body 2 and the disk body 1 and the end of the tail body 2 away from the disk body 1. The groove 3 is set within the above reasonable position range, 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. If the distance L1' between the groove 3 and the end of the tail body 2 away from the disc body 1 is too small, the groove 3 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 3 is closer to the disc body 1, and the current path at the groove 3 is larger. If there is an overcurrent, it cannot be melted in time, increasing the safety risk of the battery.

[0035] In some embodiments, the variable diameter width Dn of the tail body 2 at the groove 3 has a variable diameter range of 3L / 8≤Dn<3L / 4. The variable diameter width Dn in the present application refers to that due to the design of the groove 3, the width of the tail body 2 here changes relative to the overall width L. The variable diameter width Dn along the length direction of the tail body 2 can be a specific value (for example, the shape of the groove 3 is rectangular) or a variable value (for example, the shape of the groove 3 is semicircular). Whether it is a specific value or a variable value, it is within the variable diameter range. Based on the definition of the variable diameter width Dn in the present application, the overall width L in the present application also refers to the width of the tail body at a position other than the groove 3 on the tail body 2. The variable diameter width Dn of the tail body 2 at the groove 3 can balance the mechanical properties of the tail body 2 and the safety performance of the battery within a reasonable range. When the variable diameter width Dn is too small, the strength of the tail body 2 at the groove 3 is insufficient and it is easy to be broken when bent.

[0036] In some embodiments, the variable diameter range of the variable diameter thickness Dn' of the tail body 2 at the groove 3 is D / 2<Dn'<D, and the variable diameter range of the variable diameter thickness Dn' of the tail body 2 at the groove 3 is 0.1-0.3mm. Wherein, D is the overall thickness of the tail body 2, that is, the thickness of the tail body 2 except the groove 3, which is usually a uniform thickness. According to actual needs, D is, for example, 0.15-0.35mm; the variable diameter thickness Dn' refers to the thickness designed to be reduced relative to the overall thickness D at the groove 3. Figure 5 In the side view of the tail body 2 shown, the reduction in thickness can be a sudden change. It is understandable that the reduction in thickness can also be a gradual change. By designing a variable diameter thickness at the groove 3 that is smaller than the overall thickness of the tail body 2, it helps to make the current converge to a narrower and thinner area, thereby improving the sensitivity of the tail body 2 to achieve current cutoff and ensuring the safe use of the battery. When the variable diameter thickness Dn' is greater than 0.3mm, the sensitivity improvement effect brought about by the change in thickness is not obvious; when the variable diameter thickness Dn' is less than 0.1mm, the tail body 2 is very easy to be melted, resulting in the battery being unable to be used normally.

[0037] Please refer to Figure 6 , Figure 6 Shows Figure 3 The cross-sectional view at the middle section BB', in some embodiments, the minimum cross-sectional area Sn of the tail body 2 at the groove 3 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 3 is the cross-sectional area at the narrowest and thinnest position of the groove 2, Sn = Dn * Dn'; the overall cross-sectional area S of the tail body 2 is the cross-sectional area of ​​the position on the tail body 2 other than the groove 3, S = L * D, which is usually a fixed value. 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 blown in thermal runaway, increasing the safety risk; on the contrary, when the minimum cross-sectional area Sn is too small, on the one hand, the fusing sensitivity will be too high, and on the other hand, the internal resistance will be increased, seriously affecting the normal use of the battery.

[0038] In some embodiments, the dimension Zn of the groove 3 along the length direction of the tail body 2 is 0<Zn≤L, that is, the length of the groove 3 in the vertical direction does not exceed the overall width L of the tail body 2; further preferably, 1 / 4L<Zn≤3 / 4L. In this application, the dimension of the groove 3 along the length direction of the tail body 2 refers to the length between the end of the groove 3 closest to the disc body 1 and the end farthest from the disc body 1 (see Figure 4 The size of the groove 3 along the length direction of the tail body 2 is within a reasonable range, which helps to improve the safety of the battery. If the size 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 the size is too small, the fuse sensitivity of the tail body 2 increases, and there is a possibility of fuse under a safe current.

[0039] In order to enable the tail body 2 to reach the melting point at the groove 3 and to be blown when the battery thermally runs away, the material of the current collecting plate is preferably aluminum.

[0040] The first aspect of the present application provides a positive electrode collector disk suitable for cylindrical lithium batteries. The design is simple, the tail body is uniform, and the widened design increases the current path, reduces the internal resistance, and improves the current cut-off design. Under conditions such as battery short circuit and overcharge, the notch fuses to cut off the current and prevent battery explosion, thereby improving the safety of the battery. The fusing effect is more controllable and does not affect the mechanical strength and welding performance of the tail body.

[0041] The second aspect of the present application provides a cylindrical lithium battery, including a core electrode group 4 and a battery cap, wherein the positive electrode of the core electrode group 4 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 4, 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, and the battery has low internal resistance and high safety.

[0042] 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.

[0043] 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 (4), and the tail body (2) is used to connect to a battery cap, so that a passage is formed between the core electrode group (4) and the battery cap, characterized in that: At least one groove (3) is formed on the tail body (2), and a distance L1' between a center position of the groove (3) and an end of the tail body (2) away from the disk body (1) is 60% to 80% of a length L1 of the tail body (2); At positions on the tail body (2) other than the groove (3), the tail body (2) has an overall cross-sectional area S; at the position of the groove (3), 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: At positions on the tail body (2) other than the groove (3), the tail body (2) has an overall width L; at the position of the groove (3), the tail body (2) has a variable diameter width Dn, and the variable diameter range of the variable diameter width Dn is 3L / 8≤Dn<3L / 4.

3. The positive electrode current collecting disk according to claim 2, characterized in that: At positions on the tail body (2) other than the groove (3), the tail body (2) has an overall thickness D; at the position of the groove (3), the tail body (2) has a variable diameter thickness Dn', and the variable diameter range of the variable diameter thickness Dn' is D / 2<Dn'<D.

4. The positive electrode current collecting disk according to claim 3, characterized in that: The dimension Zn of the groove (3) along the length direction of the tail body (2) is 0<Zn≤L.

5. The positive electrode current collecting disk according to any one of claims 1 to 4, characterized in that: The disc body (1) is in the shape of an axially symmetrical 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).

6. The positive electrode current collecting disk according to claim 5, characterized in that: At the connection between the disk body (1) and the tail body (2), the first side (11) and the second side (13) respectively form two left-right symmetrical connection angles (6) with two vertical sides (21) of the tail body (2).

7. The positive electrode current collecting disk according to claim 6, characterized in that: The overall width L of the tail body (2) is d*sin(∠A / 2), wherein d is the diameter of the disk body (1); ∠A has the center point corresponding to the arc (12) as its vertex, and its two sides respectively pass through the intersection points of the two vertical sides (21) of the tail body (2) and the full circle where the arc (12) is located, and 20°≤∠A≤40°.

8. The positive electrode current collecting disk according to claim 7, characterized in that: The length L1 of the tail body (2) is 85%-95% of the diameter d of the disc body (1).

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: It comprises the wound core electrode group (4) and a battery cap, wherein the positive electrode of the wound core electrode group (4) forms a passage with the battery cap through the positive electrode current collecting disk; wherein the disk body (1) is connected to the wound core electrode group (4), and the tail body (2) is connected to the battery cap.

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