Cylindrical lithium ion battery

Abstract

The cylindrical lithium ion battery comprises a positive current collecting plate and a negative current collecting plate, the positive current collecting plate comprises a first plate body and a second plate body, the first plate body is provided with a first center hole, the second plate body comprises a connecting part, the connecting part is provided with a fusing groove, and the edge of the second plate body is provided with a plurality of first notches; a negative collector plate comprises a third plate body and a flange protruding along one side of the outer periphery of the third plate body, the shape of the third plate body is a closed pattern formed by sequentially connecting a plurality of arc edges and a plurality of concave edges end to end alternately, the flange is arranged on the arc edges, a second notch is formed in the concave edge of the third plate body, and the second notch is arranged in the third plate body. The third disc body is provided with a second center hole, and the conditions that the range of S4b / S4a is 2%-10%, and the range of H4b / H4a is 42%-58% are further met. When the cylindrical lithium ion battery is assembled, liquid injection can be carried out on the positive electrode side or the negative electrode side, a liquid injection scheme can be conveniently adjusted according to actual process requirements, and meanwhile, the cylindrical lithium ion battery has the characteristics of good safety, high welding reliability and good battery performance.

Description

Technical Field

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

[0002] At present, in large cylindrical lithium-ion batteries such as the 46 series, positive and negative collector plates are usually included, wherein the positive collector plate is used to conduct the positive pole of the battery with the positive pole of the winding core, and the positive collector plate is used to conduct the metal shell of the battery with the negative pole of the winding core. In the current large cylindrical lithium-ion batteries, the positive and negative collector plates are only designed from the above perspectives. However, the structure of the positive and negative collector plates has a significant impact on the performance, reliability and manufacturing cost of the battery, for example:

[0003] When assembling cylindrical lithium-ion batteries, the solution of injecting liquid on the negative electrode side of the battery is usually adopted. In this case, in order to meet the demand of injecting liquid on the negative electrode side, the negative electrode collector plate will be designed with a corresponding structure. Correspondingly, since there is no need for injection on the positive electrode side of the battery, the positive electrode collector plate adopts a simple sheet structure design to reduce design and manufacturing costs. It is understandable that due to the limitations of the positive electrode collector plate structure, it is not possible to easily adjust the injection scheme to achieve injection on the positive electrode side during the manufacturing process. If the manufacturer needs to adjust the injection scheme, it is necessary to change and verify the structure of the positive electrode collector plate separately to meet the demand of injecting liquid on the positive electrode side of the battery. Therefore, the current positive electrode collector plate structure is difficult to meet the demand for injection on the positive electrode side of the battery, and further, it is difficult to meet the demand for flexible production of 46 series cylindrical lithium batteries.

[0004] In addition, the negative electrode collector plate is usually provided with a circle of flange. When assembling the cylindrical lithium-ion battery, the outer surface of the flange is attached to the shell wall of the shell and connected by penetration welding, so that the shell and the negative electrode of the core are conductively connected. However, if the solution of injecting liquid on the negative electrode side is adopted, the flange of the negative electrode collector plate mentioned above is tightly connected with the inner wall of the shell, and the electrolyte can only enter the battery through the injection hole in the middle of the negative electrode collector plate. The injection efficiency is low and overflow problems are very likely to occur. For cylindrical lithium-ion batteries using the above-mentioned pressure relief solution, if a short circuit or other thermal runaway occurs during use, a large amount of gas will be generated in the shell, and the plate body and flange of the negative electrode collector plate will hinder the gas from being discharged from the negative electrode side, thereby increasing the safety risk of the battery.

[0005] In addition, for the flange of the above structure, when it is welded to the shell, the weld line formed is longer, and the risk of welding quality problems is higher when the welding is too long. For example, leakage, cold welding, missing welding and other welding quality problems may occur at the weld line, thereby increasing the internal resistance of the battery cell. Summary of the invention

[0006] The embodiment of the present application provides a cylindrical lithium-ion battery to at least solve the technical problems of the existing cylindrical lithium-ion batteries such as high manufacturing cost, limited performance, poor reliability and insufficient safety due to unreasonable design of positive electrode collector plates and negative electrode collector plates.

[0007] The embodiment of the present application provides a cylindrical lithium-ion battery, comprising a shell and a positive electrode current collecting disk, a winding core and a negative electrode current collecting disk arranged in the shell, wherein the shell is provided with a pole on the positive electrode side, and the pole has a penetrating injection hole, wherein:

[0008] The positive electrode current collector disk comprises a first disk body located in the center and a second disk body connected to the edge of the first disk body and extending radially outward, the first disk body is welded to the pole, and a first center hole is provided through the center of the first disk body, the first center hole is communicated with the injection hole, the second disk body comprises a connecting portion and a welding portion connected thereto, the welding portion is connected to the edge of the first disk body by the connecting portion, the connecting portion is provided with a fuse groove at the edge along the length direction thereof, the welding portion is welded to the positive electrode of the winding core, and a plurality of first notches are provided at the edge of the second disk body;

[0009] The negative electrode current collector disk includes a third disk body and a flange protruding along one side of the outer peripheral edge of the third disk body. The third disk body is welded to the negative electrode of the winding core. The shape of the third disk body is a closed figure composed of multiple arc edges and multiple concave edges alternately connected end to end in sequence. The flange is arranged on the arc edge. The third disk body forms a second notch at the concave edge. A second center hole is provided through the center of the third disk body. The area of ​​the third disk body is S4a, and the total area of ​​the second notch is S4b. The range of S4b / S4a is 2% to 10%. The circumference of the third disk body is H4a, and the total arc length of the flange is H4b. The range of H4b / H4a is 42% to 58%.

[0010] The cylindrical lithium-ion battery according to the embodiment of the present application has at least the following beneficial effects:

[0011] First, by opening the first center hole, the first notch, the second center hole, and the second notch on the positive electrode collector and the negative electrode collector, the cylindrical lithium-ion battery can be filled on the positive electrode side or the negative electrode side during assembly, and the filling scheme can be conveniently adjusted according to actual process requirements. In addition, the first notch or the second notch also helps to improve the filling efficiency and assists in exhaust when the internal pressure of the battery increases.

[0012] Secondly, a fuse slot is provided on the positive current collector, which can reduce the width of the connection portion. In the abnormal case of excessive current, when the current passes through this location, the heat increases and reaches the melting point, causing the connection portion to fuse at this location, thereby achieving the effect of cutting off the current. This enables the positive current collector to have a fuse protection function, which can improve the safety of the cylindrical lithium battery.

[0013] Furthermore, in the negative electrode current collector, by setting the flange only at the edge of the arc and setting the range of H4b / H4a at 42% to 58%, the length of the weld line between it and the shell can be effectively reduced, thereby reducing the risk of leakage, cold welding and leaking welding at the welding point, the welding reliability is higher, and the internal resistance of the battery can be reduced. In addition, the weight of the negative electrode current collector can also be effectively reduced to increase the energy density of the battery.

[0014] In a possible implementation, the area of ​​the first disk body is S2a, the area of ​​the first center hole is S2b, and the range of S2b / S2a is 4.2% to 8.6%; the area of ​​the second center hole is S4c, and the range of S4c / S4a is 1% to 3%.

[0015] In a possible embodiment, along the thickness direction of the positive electrode current collecting disk, the first disk body is higher than the second disk body, and the height difference between the surface of the first disk body that is higher than one side of the second disk body and the surface of the second disk body on the same side is H2a, and the range of H2a is 0.6 to 1.4 mm; the third disk body is also provided with a plurality of auxiliary holes located on the periphery of the second center hole, and the total area of ​​the plurality of auxiliary holes is S4d, and the range of S4d / S4a is 9% to 21%.

[0016] In a possible embodiment, the connecting portion has a first width W2a, and the connecting portion has a second width W2b in the area where the fuse groove is opened, and the range of W2b / W2a is 42% to 63%; the connecting portion has a first edge extending along the length direction for forming the fuse groove, and the length of the first edge is L2a, and the range of L2a is 2 to 4 mm.

[0017] In a possible implementation, the connecting portion includes:

[0018] A plurality of first connection portions arranged at intervals along the circumference of the first disk body and extending radially outward from the edge thereof, wherein the fuse slot is provided at the first connection portion;

[0019] A second connection portion formed by the outer end portions of each of the first connection portions extending toward both sides along the circumferential direction;

[0020] There are a plurality of welding parts, each of which is arranged one by one in an area defined by two adjacent first connecting parts and the second connecting parts, and is formed by extending radially inwardly from the inner edge of the second connecting part;

[0021] The circumference of the third disk is H4a, the total arc length of the second notch is H4c, and the range of H4c / H4a is 25% to 38%.

[0022] In a possible embodiment, the edges on both sides of the welding portion and the inner edge of the second connecting portion define a slit extending in the circumferential direction, the circumference of the outer edge of the second connecting portion is L2b, the total arc length of the slit is L2c, and the range of L2c / L2b is 43% to 58%; the shape of the concave edge is arc-shaped, and the maximum depth of the second notch is H4d, and the range of H4d is 2 to 5 mm.

[0023] In a possible embodiment, the first notch is arranged at the outer edge of the second connecting part corresponding to the position of the welding part, the circumference of the outer edge of the second connecting part is L2b, the total arc length of the first notch is L2d, and the range of L2d / L2b is 4% to 9%; the radius of the third disk body is L4a, and the third disk body is also provided with a plurality of auxiliary holes located on the outer periphery of the second center hole, and the inner edge of the auxiliary hole is at a distance from the center of the second center hole of L4b, and the range of L4b / L4a is 18% to 36%.

[0024] In a possible implementation manner, the maximum depth of the first notch is L2f, and the range of L2f is 0.9-2.1 mm; the auxiliary hole is a waist-shaped hole, and the long axis direction of the auxiliary hole is consistent with the radius direction of the third disk body.

[0025] In a possible implementation manner, the width of the slit along the radial direction is L2e, and the range of L2e is 0.4-1.5 mm; the third disk body and the flange are integrally formed and connected.

[0026] In a possible embodiment, the second connecting portion has a radial width W2c in the area corresponding to the slit, and the range of W2c is 1 to 3 mm; the third disk body is also provided with an auxiliary hole located on the outer periphery of the second center hole, and the number of the arc edge, the concave edge and the auxiliary hole is 4, the 4 arc edges and the 4 auxiliary holes are arranged in one-to-one correspondence, and the midpoint of the corresponding arc edge, the center of the auxiliary hole and the center of the second center hole are collinear. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 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.

[0028] Figure 1 is a cross-sectional schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application;

[0029] Figure 2 It is a structural schematic diagram of a positive electrode current collector provided in an embodiment of the present application;

[0030] Figure 3 yes Figure 2 Schematic diagram of area S2a in the positive electrode current collecting disk;

[0031] Figure 4 yes Figure 2 Schematic diagram of area S2b in the positive electrode current collecting disk;

[0032] Figure 5 yes Figure 3 Schematic cross-sectional view along the AA direction;

[0033] Figure 6 yes Figure 5 The local schematic diagram of point B in the middle;

[0034] Figure 7 yes Figure 1 A schematic top view of the positive electrode current collecting disk in FIG.

[0035] Figure 8 yes Figure 7 The local schematic diagram of the C in the middle;

[0036] Fig. 9 yes Figure 7 The local schematic diagram of point D in the middle;

[0037] Fig.10 It is a schematic diagram of the structure of a negative electrode current collector provided in an embodiment of the present application;

[0038] Fig.11 yes Fig.10 Schematic diagram of the assembly of the middle negative electrode current collector, winding core and shell;

[0039] Fig.12 yes Fig.10 A schematic front view of the middle negative electrode current collecting plate;

[0040] Fig.13 yes Fig.10 A schematic diagram of the area S4a of the middle negative electrode current collecting disk;

[0041] Fig.14 yes Fig.10 A schematic diagram of the area S4b of the middle negative electrode current collecting disk;

[0042] Fig.15 yes Fig.10 A schematic diagram of the area S4c of the middle negative electrode current collecting disk;

[0043] Fig.16 yes Fig.10 A schematic diagram of the area S4d of the middle negative electrode current collecting disk;

[0044] Fig.17 yes Fig.10 Schematic diagram of the front view of the negative electrode collector plate. DETAILED DESCRIPTION

[0045] Figure 1 Schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application. The cylindrical lithium-ion battery in the embodiment of the present application includes various large cylindrical lithium-ion batteries, such as 46 series (outer diameter is 46 mm), which is not limited here. Figure 1 As shown, the cylindrical lithium-ion battery includes a housing 100, a positive electrode current collecting disc 200, a winding core 300, a negative electrode current collecting disc 400, a pole 500, a negative electrode cover plate 600, and a sealing nail 700.

[0046] The shell 100 is cylindrical as a whole, and has a positive side and a negative side opposite to each other. The pole 500 is installed on the positive side of the shell 100 as part of the positive cover plate assembly, and the negative cover plate 600 is installed on the negative side of the shell 100. The shell 100 defines an inner cavity, and the positive current collector 200, the winding core 300, the negative current collector 400, etc. are all enclosed in the inner cavity. The positive electrode of the winding core 300 is connected to the pole 500 through the positive current collector 200, and the negative electrode of the winding core 300 is connected to the shell 100 through the negative current collector 400. It can be understood that the pole 500 is used as the positive electrode of the cylindrical lithium-ion battery, and the shell 100 is used as the negative electrode of the cylindrical lithium-ion battery, which are respectively used to be electrically connected to external electrical equipment.

[0047] It is understandable that the negative electrode cover 600 of the cylindrical lithium-ion battery is provided with an injection hole sealed by a sealing nail 700, through which electrolyte can be injected into the interior of the cylindrical lithium-ion battery through the side of the negative electrode cover 600, and at the same time, a structure such as an injection explosion-proof groove can be constructed on the negative electrode cover 600 to open in time to release pressure when the pressure inside the cylindrical lithium-ion battery increases abnormally. Similarly, an injection hole 510 is also provided on the pole 500, through which electrolyte can be injected into the interior of the cylindrical lithium-ion battery on the positive side.

[0048] It can be understood that the winding core 300 is formed by stacking the positive electrode sheet, the negative electrode sheet and the separator, and then winding them. Figure 1 As shown, the winding core 300 is cylindrical as a whole, and has a positive terminal 310 serving as a positive electrode and a negative terminal 320 serving as a negative electrode, wherein the positive terminal 310 is used for welding with the positive electrode collector 200, and the negative terminal 320 is used for welding with the negative electrode collector 400, and the winding core 300 is made by a winding process, and a circular winding core hole 330 is formed at the center of the winding core 300 after winding.

[0049] The positive electrode current collecting disk 200 is described in detail below.

[0050] Figure 2 is a schematic diagram of the structure of a positive electrode current collector provided in an embodiment of the present application, such as Figure 2 As shown, the positive electrode current collecting disc 200 includes a first disc body 210 and a second disc body 220, wherein the first disc body 210 is used to connect with the pole 500, and the second disc body 220 is used to connect with the winding core 300, so as to form a passage between the winding core 300 and the pole 500. It can be understood that, as Figure 2 As shown, in the cylindrical lithium-ion battery, the pole 500 and the winding core 300 are respectively located in the thickness direction of the positive electrode current collecting disk 200 ( Figure 1 Therefore, the upper surface of the first disk body 210 is connected to the bottom of the pole 500, and the lower surface of the second disk body 220 is connected to the positive terminal 310 of the winding core 300.

[0051] It is understandable that, in order to adapt to the circular cross-sectional shape of the winding core 300 and the shell 100, and to improve the space utilization, the positive electrode collector disk 200 is in the shape of a circular thin disk, and can usually be made of materials such as aluminum. In addition, in order to correspond to the position of the pole 500 in the cylindrical lithium-ion battery, the first disk body 210 is located in the central area of ​​the positive electrode collector disk 200, and the second disk body 220 is located in the peripheral area of ​​the positive electrode collector disk 200, that is, when viewed in the radial direction, the second disk body 220 is formed by radially extending from the edge of the first disk body 210. As a result, the lower surface of the second disk body 220 can just correspond to the positive terminal 310 outside the winding core hole 330.

[0052] Furthermore, the pole 500 of the cylindrical lithium-ion battery is generally a columnar structure with a circular bottom surface. In order to match the circular bottom surface shape of the pole 500, in some embodiments, such as Figure 2 As shown, the first disk body 210 can be circular, and in order to match the annular end face shape of the positive terminal 310, the second disk body 220 can be annular, thereby, the required welding area can be formed between the first disk body 210 and the pole 500, and between the second disk body 220 and the positive terminal 310, so as to form a good welding connection between the two.

[0053] Continue to refer Figure 2 In the embodiment of the present application, a first center hole 211 is provided at the center of the first disk body 210, and the first center hole 211 is used for injecting liquid on the positive electrode side. Figure 1 On the positive electrode side of the cylindrical lithium-ion battery, by providing an injection hole 510 on the pole 500, the injection hole 510 can be aligned with and connected to the first center hole 211, so that electrolyte can be injected from the outside through the channel formed by the injection hole 510 and the first center hole 211, so as to achieve injection on the positive electrode side. Further, in order to match the shape of the circular winding core hole 330, the first center hole 211 is preferably a circular hole.

[0054] It can be understood that the positive electrode current collecting plate 200 provided in the embodiment of the present application is compatible with either the negative electrode side injection or the positive electrode side injection by setting the first center hole 211 on the first plate body 210 for cylindrical lithium-ion batteries in combination with the negative electrode current collecting plate 400 capable of injecting liquid on the negative electrode side. Therefore, in the injection process, it is possible to freely choose to inject liquid on the positive electrode side or the negative electrode side without making any structural changes to the positive electrode current collecting plate 200. Manufacturers can manufacture or purchase it as a general structural part, which can effectively reduce design and manufacturing costs and facilitate internal material management in the factory.

[0055] refer to Figure 3 and Figure 4 In the embodiment of the present application, the area of ​​the first plate 210 is S2a, the area of ​​the first center hole 211 is S2b, and the range of S2b / S2a is 4.2% to 8.6%. For example, S2b / S2a can be 4.2%, 5%, 6.8%, 8.6%, etc. In some embodiments, the area S2a of the first plate 210 is 107.51mm 2 , the area S2b of the first center hole 211 is 7.51 mm 2 . If S2b / S2a is greater than 8.6%, the effective welding area of ​​the welding area of ​​the first disk body 210 will be reduced, thereby reducing the current capacity of the weld, and causing the overcurrent temperature rise in the weld area to increase, which will increase the internal resistance of the battery and reduce the overall performance of the battery. On the contrary, if S2b / S2a is less than 4.2%, during the injection, the electrolyte inflow time is too long, which reduces the injection efficiency, and further reduces the production efficiency and increases the manufacturing cost of the battery. By setting the range of S2b / S2a to 4.2% to 8.6%, the welding effect and injection efficiency of the positive electrode current collector 200 and the pole 500 can be taken into account.

[0056] In some embodiments, the diameter of the first center hole 211 ranges from 2 to 4 mm. For example, the diameter of the first center hole 211 is 2 mm, 3 mm, or 4 mm. If the diameter of the first center hole 211 is greater than 4 mm, the effective welding area of ​​the welding area of ​​the first disk body 210 will be reduced, thereby reducing the flow capacity of the weld, and will cause the flow temperature rise in the weld area to increase, thereby increasing the internal resistance of the battery and reducing the overall performance of the battery. On the contrary, if the diameter of the first center hole 211 is less than 2 mm, the electrolyte inflow time is too long during injection, thereby reducing the injection efficiency, thereby reducing the production efficiency and increasing the manufacturing cost of the battery. By setting the diameter of the first center hole 211 to 2 to 4 mm, the welding effect and injection efficiency of the positive current collector 200 and the pole 500 can be taken into account.

[0057] In some embodiments, Figure 3 and Figure 4 As shown, combined with Figure 1 , along the thickness direction of the positive electrode current collecting disc 200, the first disc body 210 and the second disc body 220 are staggered, that is, the first disc body 210 is higher than the second disc body 220. It can be understood that at this time, a pit 260 is formed in the area corresponding to the first disc body 210 at the bottom of the positive electrode current collecting disc 200. Therefore, after the positive electrode current collecting disc 200 is assembled to the cylindrical lithium-ion battery, the bottom of the first disc body 210 can define a chamber with the positive terminal 310 of the winding core 300. When the liquid is injected, the chamber can temporarily store the electrolyte injected through the first center hole 211. In addition, since the surface of the first disc body 210 used for welding with the pole 500 is not coplanar with the upper surface of the second disc body 220, its surface area is small, so the surface flatness of the first disc body 210 can be well guaranteed, so that it can fit well with the bottom surface of the pole 500, thereby improving the welding effect.

[0058] Furthermore, a liquid outlet 270 is provided on the positive electrode current collecting disk 200 to connect the recess 260 and the upper surface of the second disk body 220. It is understandable that during liquid injection, the electrolyte entering the chamber can spread to the upper surface of the second disk body 220 through the liquid outlet 270, and be injected into the interior of the winding core 300 through the through-hole structure constructed on the second disk body 220, such as the slit 240 and the first notch 250 to be described below, thereby effectively improving the liquid injection efficiency.

[0059] Furthermore, in some embodiments, the height difference between the side surface of the second plate 220 close to the first plate 210 and the surface of the first plate 210 is H2a, and the range of H2a is 0.6-1.4mm. For example, H2a can be 0.6mm, 0.8mm, 1.1mm or 1.4mm. It should be noted that the surface of the first plate 210 described here refers to the surface used for welding with the pole 500, that is, Figure 3 and Figure 4 The upper surface of the second plate 220, and the side surface of the second plate 220 close to the first plate 210 refers to the surface located on the same side as the surface for welding with the pole 500, that is, Figure 3 and Figure 4 . If H2a is greater than 1.4mm, the positive electrode current collector disc 200 will occupy the assembly space of the battery internal winding core 300, resulting in a decrease in the capacity and performance of the battery. On the contrary, if H2a is less than 0.6mm, the height of the first disc 210 relative to the second disc 220 is too low, resulting in the chamber space formed between the bottom of the first disc 210 and the positive terminal 310 of the winding core 300 being too small. During injection, the electrolyte flows out of the chamber to the surface of the second disc 220, and the time to be injected into the winding core 300 through the through-hole structure on the second disc 220 is too long, thereby reducing the injection efficiency, thereby reducing the production efficiency, increasing the manufacturing cost of the battery, and the risk of electrolyte overflowing from the injection hole during injection is also high. By setting the range of H2a to 0.6-1.4mm, the battery performance and injection efficiency can be balanced.

[0060] In some embodiments, Figure 2 , Figure 3 , Figure 4 as well as Figure 7As shown, the second disk 220 includes a connecting portion 221 and a welding portion 222 connected to each other, and the welding portion 222 is connected to the edge of the first disk 210 by the connecting portion 221. It can be understood that, among the connecting portion 221 and the welding portion 222 constituting the second disk 220, the welding portion 222 is used to be welded to the positive terminal 310 of the winding core 300, and the connecting portion 221 is used to connect the welding portion 222 to the first disk 210. In this embodiment, a fuse slot 230 is provided at the edge of the connecting portion 221 along its length direction. Specifically, the fuse slot 230 is a structure formed by the edge of the connecting portion 221 in the length direction being concave in the width direction. The fuse slot 230 can reduce the width of the connecting portion 221. In the abnormal case of excessive current, when the current passes through this place, the heat rises and reaches the melting point, so that the connecting portion 221 is melted at this position, achieving the effect of cutting off the current, thereby reducing the risk of thermal runaway of the battery cell. It is understandable that when the second disk body 220 is provided with multiple groups of connection parts 221 and welding parts 222, each connection part 221 is provided with a fuse slot 230 so as to completely cut off the current flowing through the positive current collecting disk 200 in the abnormal situation of excessive current.

[0061] Specifically, the connection portion 221 is in the shape of an elongated strip and extends in the radial direction, with a certain width extending in the circumferential direction. There are a total of two fuse slots 230 on each connection portion 121, and these two fuse slots 230 are symmetrically arranged on both sides of the width direction of the connection portion 221. In addition, since the positive electrode current collecting disk 200 itself is in the shape of a thin sheet, the connection portion 221 is also in the shape of a thin sheet in terms of thickness. Therefore, by arranging the fuse slots 230 on both sides in the width direction thereof, the cross-sectional area of ​​the section at this position can be significantly reduced, so that the connection portion 221 can be quickly blown under abnormal conditions of excessive current.

[0062] Further, refer to Figure 8 In some embodiments, the connection portion 221 has a first width W2a, and the connection portion 221 has a second width W2b in the area where the fuse slot 230 is provided, and the range of W2b / W2a is 42% to 63%. For example, W2b / W2a can be 42%, 48%, 56%, 63%, etc. In some embodiments, the first width W2a is 4mm, and the second width W2b is 2mm. The second width W2b in the embodiment of the present application means that due to the design of the fuse slot 230, the width of the connection portion 221 changes relative to the first width W2a. Based on the definition of the second width W2b in the embodiment of the present application, the first width W2a in the present application also refers to the width of the connection portion 221 at a position other than the fuse slot 230 on the connection portion 221. Furthermore, the first width W2a and the second width W2b are equal in width.

[0063] If W2b / W2a is greater than 63%, the second width W2b of the connection portion 221 at the corresponding fuse slot 230 is too wide, and it cannot be quickly fused under abnormal conditions of excessive current, increasing safety risks. On the contrary, if W2b / W2a is less than 42%, the second width W2b of the connection portion 221 at the corresponding fuse slot 230 is too small, which will make the fusing sensitivity too high, easily causing the battery to fail due to short circuit, and on the other hand, increase the internal resistance, affecting the normal use of the battery. By setting the range of W2b / W2a to 42% to 63%, the fusing effect of the connection portion 221 can be guaranteed, thereby ensuring the safety performance of the battery.

[0064] In some embodiments, the connection portion 221 has a first edge 231 extending along the length direction for forming the fuse slot 230, and the length of the first edge 231 is L2a, and the range of L2a is 2 to 4 mm. For example, L2a is 2 mm, 3 mm or 4 mm. As mentioned above, the positive electrode collector 200 is usually made of aluminum, which is soft and has low strength. Therefore, if L2a is greater than 4 mm, the connection portion 221 is more likely to deform or even break at the location of the fuse slot 230, and the positive electrode collector 200 itself is easily scrapped, causing waste and increasing the difficulty of management. In addition, if the metal shavings generated thereby fall into the battery, there is a risk of battery short circuit, and the burrs and sharp corners at the cross section also have the risk of piercing the diaphragm and causing the battery short circuit, thereby increasing the safety risk of the battery. On the contrary, if L2a is less than 2mm, heat is easily transferred to the first plate 210 and the welding part 222, which will reduce the fusing sensitivity of the fusing slot 230 and prolong the fusing time, thereby increasing the safety risk of the battery. By setting the range of L2a to 2-4mm, the yield rate can be improved while ensuring the safety of the battery, thereby reducing the cost.

[0065] It can be understood that, in this embodiment, both sides of the connecting portion 221 in the width direction are provided with the fuse slots 230, so the aforementioned second width W2b is the vertical distance between the first edges 231 of the two fuse slots 230. Figure 8 As shown, in addition to the first edge 231, the bottom of the fuse slot 230 also has a second edge 232 and a third edge 233 respectively connected to the two ends of the first edge 231, and the first edge 231, the second edge 232 and the third edge 233 together constitute the fuse slot 230 which is generally trapezoidal in shape.

[0066] Continue to refer Figure 2 , Figure 3 , Figure 4 as well as Figure 7In some embodiments, the second disk body 220 includes a connecting portion 221 and a welding portion 222. Further, the connecting portion 221 includes a first connecting portion 2211 and a second connecting portion 2212. There are multiple first connecting portions 2211, which are arranged at intervals along the circumference of the first disk body 210 and extend radially outward from its edge. In other words, these first connecting portions 2211 are distributed in a radial shape with the center of the first disk body 210 as the center. The second connecting portion 2212 is formed by the outer end of each first connecting portion 2211 extending to both sides along the circumference. In addition, there are multiple welding portions 222, each of which is correspondingly arranged in the area jointly defined by two adjacent first connecting portions 2211 and the second connecting portion 2212, and is formed by the inner edge of the second connecting portion 2212 extending radially inward. It can be understood that the second connection parts 2212 formed by the outer ends of each first connection part 2211 extending circumferentially constitute an annular structure surrounding the periphery of the first disk body 210, and the outer edge of this annular structure is used to define the boundary of the entire positive electrode current collecting disk 200.

[0067] It is understandable that, in order to simplify the structure, the aforementioned fuse slot 230 can be disposed on the first connecting portion 2211 .

[0068] It can be understood that in the above structure, a plurality of welding portions 222 for welding with the positive terminal 310 are provided, and the number thereof corresponds to the number of the first connection portions 2211. For example, the number of the first connection portions 2211 is 3, and the number of the welding portions 222 is also 3 accordingly, and these welding portions 222 are arranged in a plurality of areas separated by the first connection portions 2211 along the circumferential direction, so that when observing from the top view of the positive electrode current collecting disk 200, it is divided into a plurality of welding areas, and the boundaries of these welding areas are clear. Therefore, during welding, it is easy to position by tooling and to weld by welding equipment, and after welding, it is convenient to judge whether the welding position is reasonable by visual observation or visual inspection equipment, which can reduce the difficulty of identification and the workload.

[0069] It can be further understood that the welding portion 222 is formed by extending inward from the inner edge of the second connecting portion 2212. In some embodiments, in order to increase the welding area of ​​each welding portion 222 (see Figure 7The edge of the welding part 222 extends to the edge of the first disk body 210 and the edge of the first connecting part 2211, so that there is a gap extending in the circumferential direction between the welding part 222 and the first disk body 210, and the gap can be used as the aforementioned liquid outlet 270, so that when the liquid is injected, the electrolyte entering the chamber can spread to the upper surface of the second disk body 220 through the liquid outlet 270. Further, there is a gap extending in the radial direction between the welding part 222 and the first connecting parts 2211 located on both sides thereof, and the gap can be used as a through-hole structure for injecting liquid into the winding core 300. It can be understood that in the above structure, the gap formed between the welding part 222 and the first disk body 210 and the first connecting part 2211 is connected, so the electrolyte can flow along the two gaps, which can improve the injection efficiency.

[0070] Furthermore, in some embodiments, Figure 7 As shown, the edges on both sides of the welding portion 222 and the inner edges of the second connecting portion 2212 define a slit 240 extending in the circumferential direction. By defining the slit 240 extending in the circumferential direction on the edges on both sides of the welding portion 222 and the inner edges of the second connecting portion 2212, during liquid injection, at the far end away from the first disk body 210, the electrolyte can be injected into the interior of the winding core 300 through the slit 240, thereby improving the injection efficiency.

[0071] In some embodiments, the circumference of the outer edge of the second connecting portion 2212 is L2b, the total arc length of the slit 240 is L2c, and the range of L2c / L2b is 43% to 58%. For example, L2c / L2b can be 43%, 50%, 58%, etc. For example, in some embodiments, L2b is 233.52mm, the number of welding portions 222 is 3, the number of slits 240 is 6, and the total arc length L2c of the 6 slits 240 is 66.78mm. It should be noted that the circumference L2b referred to in the embodiments of the present application refers to the circumference of the entire circle where the outer edge of the circular ring structure formed by the second connecting portion 2212 extending circumferentially from the outer end of each first connecting portion 2211 is located, that is, Figure 7 The circumference of the circle where the reference line F at the first notch 250 is located is for ease of understanding. Figure 7 The outer edge of the second connection portion 2212 is indicated by a dotted line. Fig. 9Only a part of L2c is marked, that is, the arc length of a section of the slit 240, and L2c here also includes the arc length of the gap formed by the welding portion 222 and the first connecting portion 2211 connected to the slit 240. If L2c / L2b is greater than 58%, the structural strength of the connecting portion between the welding portion 222 and the second connecting portion 2212 is low, and it is easy to deform, which is difficult to ensure the welding effect, and the low yield rate will also lead to increased costs. On the contrary, if L2c / L2b is less than 43%, when injecting liquid, the time required for the electrolyte to be injected into the inside of the winding core through the slit 240 is still long, and the slit 240 does not significantly improve the injection efficiency. By setting the range of L2c / L2b to 43% to 58%, the injection efficiency can be improved while ensuring the welding effect of the positive electrode collector 200, and the yield rate can also be improved to reduce costs.

[0072] Further, in some embodiments, the width of the slit 240 in the radial direction is L2e, and the range of L2e is 0.4 to 1.5 mm. For example, L2e is 0.4 mm, 0.8 mm, 1.2 mm or 1.5 mm, etc. If L2e is greater than 1.6 mm, the opening area of ​​the slit 240 will occupy the welding area between the welding portion 222 and the winding core 300, resulting in a reduction in the effective welding area, causing the flow capacity of the weld to decrease, and then causing the temperature rise of the weld to increase. On the contrary, if L2e is less than 0.4 mm, during liquid injection, the speed at which the electrolyte flows into the inside of the winding core 300 through the slit 240 is slow, and the slit 240 does not significantly improve the injection efficiency. By setting the range of L2e to 0.4 to 1.5 mm, the welding effect and injection efficiency of the positive electrode current collecting disk 200 and the winding core 300 can be taken into account.

[0073] Further, in some embodiments, the second connection portion 2212 has a width W2c in the radial direction in the corresponding slit 240 area, and the range of W2c is 1 to 3 mm. For example, W2c can be 1 mm, 3 mm, etc. If W2c is greater than 3 mm, the second connection portion will excessively invade the central area of ​​the positive current collector 200, so that the effective welding area between the welding portion 222 and the winding core 300 is reduced, resulting in a decrease in the current capacity of the welding point, and then the temperature rise of the welding point will increase. On the contrary, if W2c is less than 1 mm, the structural strength of the second connection portion 2212 at this position is insufficient, and it is easy to break. If the metal chips generated thereby fall into the battery, there will be a risk of battery short circuit, and the burrs and sharp corners at the cross section will also have the risk of piercing the diaphragm and causing the battery short circuit, thereby increasing the safety risk of the battery. By setting the range of W2c to 1 to 3 mm, the welding effect of the positive current collector 200 and the winding core 300 and the safety of the battery can be taken into account.

[0074] In some embodiments, Figure 7 As shown, the second connection portion 2212 is provided with a plurality of evenly distributed first notches 250 on the outer edge. Specifically, for example, the first notches 250 can be formed by the outer edge of the second connection portion 2212 being concave inwardly along the radial direction. Thus, the first notches 250 are defined by the concave edge of the second connection portion 2212 and its reference line, wherein the reference line F can refer to Fig. 9 The dotted line at the first notch 250 in the figure is used for illustration only. The dotted line represents the shape when the notch 113 is not formed on the outer edge of the second connection part 2212, that is, the dotted line is obtained by extending the outer edge of the second connection part 2212 according to its natural direction. By providing the first notch 250, during liquid injection, the electrolyte that spreads along the upper surface of the second disk body 220 to its edge can flow into the inside of the winding core 300 along the first notch 250, thereby further improving the liquid injection efficiency.

[0075] Further, in some embodiments, the circumferential position of the first notch 250 in the second connecting portion 2212 corresponds to the welding portion 222, that is, along the radial direction, the center of the first notch 250 is collinear with the center of the welding portion 222, and the total arc length of the first notch 250 is L2d, and the range of L2d / L2b is 4% to 9%. For example, L2d / L2b can be 4%, 6%, 9%, etc. For example, in some embodiments, the number of first notches 250 is 3, and the total arc length L2d of the 3 first notches 250 is 9 mm. It should be noted that the arc length of the first notch 250 referred to in the embodiments of the present application refers to the arc length of the reference line F that defines the formation of the first notch 250, therefore, Fig. 9 Only a portion of L2d is identified. If L2d / L2b is greater than 9%, the connection area between the second connection portion 2212 and the welding portion 222 is too small, which makes it difficult to ensure the flatness of the welding portion 222, and thus the welding effect is difficult to ensure. On the contrary, if L2d / L2b is less than 4%, during injection, the electrolyte flows slowly through the first notch 250 into the interior of the winding core 300, and the first notch 250 does not significantly improve the injection efficiency. By setting the range of L2d / L2b to 4% to 9%, both the welding effect and the injection efficiency of the positive electrode current collector 200 can be taken into account.

[0076] Furthermore, in some embodiments, Fig. 9As shown, the maximum depth of the first notch 250 is L2f, and the range of L2f is 0.9 to 2.1 mm. For example, L2f is 0.9 mm, 1.5 mm or 2.1 mm. If L2f is greater than 2.1 mm, the first notch 250 will occupy the welding area between the welding portion 222 and the core 300, resulting in a reduction in the effective welding area, causing the current capacity of the weld to decrease, and then causing the temperature rise of the weld to increase. On the contrary, if L2f is less than 0.9 mm, during liquid injection, the electrolyte flows into the core 300 through the first notch 250 at a slow speed, and the first notch 250 does not significantly improve the injection efficiency. By setting the range of L2f to 0.9 to 2.1 mm, the welding effect and injection efficiency of the positive electrode current collector 200 can be taken into account.

[0077] The effects of the present application are further described below with specific examples and comparative examples.

[0078] It should be noted that the following embodiments and comparative examples of the present application are designed and manufactured based on the 4680 cylindrical lithium-ion battery commonly used in the art. Therefore, in addition to manufacturing the negative electrode collector 400 according to the aforementioned structure, other components and materials can be obtained by referring to the 4680 cylindrical lithium-ion battery. For example, after the positive electrode sheet and the negative electrode sheet are rolled, slit, and die-cut, they are wound together with the diaphragm, and the positive electrode sheet, the negative electrode sheet, and the diaphragm are wound by a winding machine to form a winding core 300, and the two ends of the winding core 300 are cut and stacked to form positive and negative pole ears, and then the negative electrode collector 400 and the positive electrode collector are welded to the winding core 300, and then the negative electrode collector 400 and the positive electrode collector are welded to the shell 100, and the negative electrode cover 600 is welded to the shell 100, and the injection, sealing, and formation processes are completed to obtain an experimental cylindrical lithium-ion battery.

[0079] Embodiment 1:

[0080] Embodiment 1 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, the positive electrode current collecting disk 200 includes a first disk body 210 and a second disk body 220 staggered in the thickness direction, the surface of the first disk body 210 higher than the second disk body 220 has a height difference H2a from the surface of the second disk body 220 on the same side, the first disk body 210 is provided with a circular first center hole 211 at the center, the second disk body 220 includes three first connecting parts 2211 extending radially outward from the edge of the first disk body 210, and the two sides of the outer ends of the three first connecting parts 2211 extend circumferentially to form There are second connection parts 2212, which together form an annular structure, and in each area formed by three first connection parts 2211 in pairs in the circumferential direction, the inner edge of the second connection part 2212 extends inward to form a welding part 222, and a slit 240 extending along the circumferential direction is defined between the edges on both sides of the welding part 222 and the inner edge of the second connection part 2212, and a pair of trapezoidal fuse grooves 230 are provided on the edges in the length direction of each first connection part 2211, and a first notch 250 is provided on the outer edge of the second connection part 2212 corresponding to the position of the welding part 222.

[0081] In addition, the positive electrode current collecting disk 200 also meets the following parameters:

[0082] The area S2a of the first plate 210 is 107.51 mm 2 , the area S2b of the first center hole 211 is 7.07 mm 2 , H2a=1mm, the first width of the first connecting portion 2211 W2a=4mm, the second width of the first connecting portion 2211 at the position where the fuse slot 230 is set W2b=2mm, the length of the first edge 231 at the bottom of the fuse slot 230 L2a=3mm, the circumference of the outer edge of the second connecting portion 2212 L2b=233.52mm, the total arc length of the 6 sections of slits 240 L2c=66.78mm, the width of the slit 240 L2e=0.8mm, the width of the second connecting portion 2212 in the area corresponding to the slit 240 W2c=2mm, the total arc length of the 3 first notches 250 L2d=9mm, and the maximum depth of the first notch 250 L2f=1.5mm.

[0083] From the above, it can be seen that in the positive electrode current collecting disk 200, S2b / S2a=6.6%, W2b / W2a=50%, L2c / L2b=50%, and L2d / L2b=6.74%.

[0084] Comparative Example 1: Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, and the difference between Comparative Example 1 and Example 1 is that: S2b / S2a=3%.

[0085] Comparative Example 2:

[0086] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200 , and the difference between Comparative Example 2 and Example 1 is that S2b / S2a=10%.

[0087] Comparative Example 3:

[0088] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200 , which is different from Example 1 in that: H2a=0.3 mm.

[0089] Comparative Example 4:

[0090] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: H2a=1.7 mm.

[0091] Comparative Example 5:

[0092] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200 , and the difference between Comparative Example 5 and Example 1 is that W2b / W2a=36%.

[0093] Comparative Example 6:

[0094] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200 , and the difference between Comparative Example 6 and Example 1 is that W2b / W2a=68%.

[0095] Comparative Example 7:

[0096] Comparative Example 7 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: L2a = 1.5 mm.

[0097] Comparative Example 8:

[0098] Comparative Example 8 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: L2a = 4.5 mm.

[0099] Comparative Example 9:

[0100] Comparative Example 9 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200 , and the difference between the comparative example 9 and the embodiment 1 is that L2c / L2b=36%.

[0101] Comparative Example 10:

[0102] Comparative Example 10 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, and the difference between the comparative example 1 and the embodiment 1 is that L2c / L2b=68%.

[0103] Comparative Example 11:

[0104] Comparative Example 11 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, and the difference between the comparative example 1 and the embodiment 1 is that L2d / L2b=2%.

[0105] Comparative Example 12:

[0106] Comparative Example 12 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, and the difference between the comparative example 1 and the embodiment 1 is that L2d / L2b=14%.

[0107] Comparative Example 13:

[0108] Comparative Example 13 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: L2e=0.3 mm.

[0109] Comparative Example 14:

[0110] Comparative Example 14 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: L2e=1.8 mm.

[0111] Comparative Example 15:

[0112] Comparative Example 15 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: W2c = 0.7 mm.

[0113] Comparative Example 16:

[0114] Comparative Example 16 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: W2c = 3.5 mm.

[0115] Comparative Example 17:

[0116] Comparative Example 17 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: L2f = 0.6 mm.

[0117] Comparative Example 18:

[0118] Comparative Example 18 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which is different from Example 1 in that: L2f = 2.6 mm.

[0119] Comparative Example 19:

[0120] Comparative Example 19 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200, which differs from Example 1 in that the fuse slot 230 is not provided.

[0121] Comparative Example 20:

[0122] Comparative Example 20 provides a cylindrical lithium-ion battery, which includes a positive electrode current collecting disk 200 , which differs from Example 1 in that the first notch 250 is not provided.

[0123] Table 1 below shows the time (t) required for electrolyte injection into the battery, the maximum welding temperature (T1max) of the first plate body 210, the maximum welding temperature (T2max) of the second plate body 220, the maximum temperature (T3max) at the fuse slot 230, the number of folding times (C1) at which the first connection portion 2211 is broken after being folded at the fuse slot 230, the number of folding times (C2) at which the second connection portion 2212 is broken after being folded, and the battery short circuit rate test for the positive electrode current collecting plate 200 manufactured in the above-mentioned embodiment and comparative example, wherein:

[0124] The test method for the time (t) required for the electrolyte to be injected into the battery is as follows: assemble the positive electrode current collecting plate 200 into a cylindrical lithium-ion battery. During the injection stage, inject 77g of electrolyte into the liquid holding cup, align the suction nozzle of the liquid holding cup with the injection hole 510 on the pole 500 and press it tightly. First, draw negative pressure in the liquid holding cup for 15s, and draw it to -90KPa. It can be observed from the liquid holding cup that the electrolyte height drops, and the electrolyte flows into the battery. After maintaining for 40s, positive pressure injection is performed, and nitrogen is flushed into the battery. The battery gradually becomes a positive pressure of 0.8MPa. The electrolyte in the liquid holding cup continues to flow into the battery, and the height of the electrolyte in the liquid holding cup gradually decreases, and then adjust to negative pressure injection, maintain, and then adjust to positive pressure injection, maintain, and the positive and negative pressure injection cycles are repeated many times until the electrolyte in the liquid holding cup completely flows into the battery, and the electrolyte height in the liquid holding cup is 0. The time t when the electrolyte completely flows into the battery is recorded at this time.

[0125] The test method for the maximum welding temperature (T1max) of the first disk 210, the maximum welding temperature (T2max) of the second disk 220, and the maximum temperature (T3max) at the fuse slot 230 is as follows: in the process of assembling the cylindrical lithium-ion battery, the temperature collection line is inserted into the battery through the injection hole 510 of the pole 500, one is attached to the welding point between the first disk 210 and the pole 500, one is attached to the welding point between the second disk 220 and the positive terminal 310 of the winding core 300, and the other is attached to the position where the fuse slot 230 is set on the first connecting part 2211, and then the normal process flow is followed to manufacture and finally obtain the finished battery, and then 10 cycles of charge and discharge are carried out at a rate of 2C, and the maximum temperatures T1max, T2max and T3max at the three positions obtained by the temperature collection line are recorded.

[0126] The test method for the number of folding times (C1) at which the first connection portion 2211 breaks after being folded at the fuse slot 230 is as follows: use scissors to cut along the radial direction from two adjacent first notches 250 to obtain a 1 / 3 piece of the positive electrode current collecting disk 200 containing a first connection portion 2211, and fold this part of the disk along the center line of the fuse slot 230. After the two surfaces are completely fitted together, unfold them to 180° and count them as one fold. Continue until a break occurs at the crease, then stop folding and record the number of folding times.

[0127] The test method for the number of folding times (C2) at which the second connection portion 2212 breaks after being folded is as follows: use scissors to cut along the radial direction from a first notch 250, and after cutting to the first center hole 211, cut radially along the edge of a first connection portion 2211 until the second connection portion 2212 is broken, and fold the obtained fan-shaped partial positive electrode current collecting disk 200 into two fan-shaped parts. The two disk surfaces are completely closed and then unfolded to 180°, which is counted as one folding, until the first connection portion 2212 breaks, stop folding, and record the number of folding times.

[0128] The test method for the battery short-circuit rate is: prepare battery samples according to the same positive and negative electrode ratio, process method and parameters, continuously produce 200 pieces, use Hipot equipment to perform short-circuit tests on the 200 pieces of semi-finished batteries obtained, and determine them as defective according to the Hipot value ≤300MΩ to calculate the battery short-circuit defect rate.

[0129] Table 1

[0130]

[0131]

[0132] It can be seen from Table 1 that when S2b / S2a is set to 6.6%, W2b / W2a is set to 50%, L2 / L2b is set to 50%, L2d / L2b is set to 6.74%, H2a is set to 1mm, L2a is set to 3mm, L2e is set to 0.8mm, W2c is set to 2mm, and L2f is set to 1.5mm, the injection time t of the electrolyte is 693 seconds, the maximum temperature T1max at the welding point between the first disk 210 and the pole 500 is 56.4°C, the maximum temperature T2max at the welding point between the second disk 220 and the winding core 300 is 68.9°C, the maximum temperature T3max at the fuse slot 230 is 73.6°C, the number of folding times C1 at which the first connecting portion 2211 is broken after being folded at the fuse slot 230 is 5 times, the number of folding times C2 at which the second connecting portion 2212 is broken after being folded is 5 times, and the battery short circuit rate is only 1%. It can be seen that within the above numerical range, the injection rate, welding temperature rise, structural strength and connection reliability of the positive electrode current collecting disc 200 can be well balanced, thereby effectively improving the safety and charge and discharge performance of the battery and reducing the production cost of the battery.

[0133] It can be seen from Table 1 that if S2b / S2a is too small, H2a is too small, W2b / W2a is too large, L2 / L2b is too small, L2d / L2b is too small, L2e is too small, L2f is too small, and the fuse slot 230 or the first notch 250 is not provided, the electrolyte injection time t will increase to a certain extent.

[0134] It can be seen from Table 1 that if S2b / S2a is too large, the maximum temperature T1max at the welding point between the first plate 210 and the pole 500 will increase significantly.

[0135] It can be seen from Table 1 that if L2 / L2b is too large, L2d / L2b is too large, L2e is too large, W2c is too large, or L2f is too large, the maximum temperature T2max at the welding point between the second disk 220 and the winding core 300 will increase.

[0136] As can be seen from Table 1, if W2b / W2a is too small, the maximum temperature T3max at the fuse slot 230 will increase significantly. If W2b / W2a is too large or L2a is too short, the maximum temperature T3max at the fuse slot 230 will be lower. It can be understood that for the location of the fuse slot 230, if the temperature cannot rise to the critical value of the fuse, the first connection portion 2211 cannot be fused in time, and thus the safety protection effect cannot be produced.

[0137] It can be seen from Table 1 that if W2b / W2a is too small or L2a is too large, the number of folding times C1 at which the first connection portion 2211 is broken after being folded at the fuse slot 230 will be reduced.

[0138] It can be seen from Table 1 that if W2c is too small, the number of folding times C2 at which the second connection portion 2212 breaks after being folded in half will be significantly reduced, and the second connection portion 2212 will be more likely to break.

[0139] It can be seen from Table 1 that if H2a is too large, the probability of battery short circuit will increase significantly.

[0140] The negative electrode current collecting disk 400 is described in detail below.

[0141] Fig.10 is a schematic structural diagram of a negative electrode current collecting disk 400 provided in an embodiment of the present application, Fig.11 yes Fig.10 A schematic diagram of the combined structure of the middle negative electrode current collecting disc 400, the winding core and the shell is shown in FIG. Fig.10 Fig.11 As shown, the negative electrode current collecting disc 400 includes a third disc body 410 and a flange 420 protruding along one side of the outer periphery of the third disc body 410, wherein the third disc body 410 is used to connect with the negative terminal 220 of the winding core 300, and the flange 420 is used to connect with the shell 100 to form a passage between the winding core 300 and the shell 100, so that the shell 100 itself serves as the negative electrode of the cylindrical lithium-ion battery.

[0142] It is understandable that the third disk body 410 and the flange 420 can be connected in any fixed connection manner. To ensure a stable connection, structural strength and processing economy, the third disk body 410 and the flange 420 can be integrally connected, for example, integrally formed by stamping.

[0143] like Fig.10 and Fig.11 As shown, the third plate body 410 is the main structural part of the negative electrode current collecting plate 400, and is in the shape of a thin sheet as a whole. A second central hole 411 and a plurality of auxiliary holes 412 are provided on the third plate body 410. In addition, a plurality of second notches 413 are provided at the outer periphery of the third plate body 410. It can be understood that the third plate body 410 has two plate surfaces that are separated from each other. Fig.10 As shown, the flange 420 protrudes from the edge of the third disk body 410 to one side at an angle approximately perpendicular to the disk surface, as shown in FIG. Fig.11 As shown, the disk surface on the side opposite to the protruding direction of the flange 420 can be used to weld to the negative terminal 220 of the winding core 300. In this case, the disk surface on the side where the flange 420 is located faces the opening direction of the shell 100. In the subsequent liquid injection process, the electrolyte will enter the battery through this side disk surface.

[0144] It is understandable that the cross-sectional shapes of the winding core 300 and the shell 100 of the cylindrical lithium-ion battery are both circular. Therefore, in order to facilitate the welding between the third plate 410 and the winding core 300, and to facilitate the welding between the flange 420 and the shell 100, for the negative electrode current collector 400, the outer contour of the third plate 410 is generally circular. In this embodiment, due to the presence of the second notch 413, the outer contour of the third plate 410 is not a complete circular shape. Fig.12 From the perspective of the third disk body 410, the shape of the third disk body 410 is a closed figure composed of a plurality of arc edges 414 and a plurality of concave edges 415 that are alternately connected end to end.

[0145] As mentioned above, the third disk body 410 is not a complete circle, but the arc-shaped edges 414 thereof can be connected to each other by extending the ends on both sides to form a complete circle, so the third disk body 410 can be regarded as a circular component.

[0146] like Fig.10 and Fig.11 As shown, in this embodiment, the flange 420 is not a complete circular ring structure. Specifically, the flange 420 is only provided at the edge of the arc edge 414, that is, it seems that the plurality of second notches 413 divide the flange 420 into multiple sections. In this way, each section of the flange 420 fits well with the shell wall surface of the shell 100 and is connected by penetration welding. At the same time, by setting the second notch 413 at the disconnection point of the flange 420, on the one hand, during the injection process, when the electrolyte flows into the disk surface of the third disk body 410, part of the electrolyte will flow directly into the battery through the second center hole 411 and the auxiliary hole 412, while part of the electrolyte will reach the outer periphery of the third disk body 410 along the disk surface of the third disk body 410. Due to the existence of the second notch 413, this part of the electrolyte will flow into the battery along the second notch 413, thereby improving the electrolyte injection efficiency, reducing the injection time, improving the production efficiency, and reducing the manufacturing cost of the battery; on the other hand, when a short circuit or thermal runaway occurs inside the battery and a large amount of gas is produced, part of the gas can be diverted through the second notch 413, thereby improving the exhaust efficiency and improving the safety of the battery.

[0147] It is understandable that only by providing the flange 420 at the position of the arc edge 414, the weight of the negative electrode current collector 400 can be reduced to a first degree, thereby improving the energy density of the battery. In addition, since the flange 420 is not a complete circle, the length of the welding line when it is welded to the shell 100 can be effectively reduced, thereby reducing the risk of leakage, cold welding, and leaking welding at the welding point, and further reducing the internal resistance of the battery.

[0148] It can also be understood that, for the negative electrode current collecting disk 400, the art generally adopts a method of opening pores inside the third disk body 410 to improve the liquid injection efficiency, and in the design process, it is also necessary to balance the weldable area of ​​the third disk body 410 itself and construct a flange 420 on the edge of the third disk body 410, etc., so as to facilitate welding with the winding core 300 and the shell 100 and design welding fixtures, and the present application divides the flange 420 into multiple sections and opens a second notch 413 on the outer periphery of the third disk body 410 to assist in liquid injection and exhaust, thereby minimizing the adverse effects on the third disk body 410 and the flange 420. For example, by reasonably designing the size and shape of the second notch 413, the impact on the welding of the third disk body 410 can be effectively avoided.

[0149] Further, from Fig.12 From the perspective of the present invention, the second notch 413 is a structure formed by being concave inward toward the center of the third disk body 410 at a position where the flange 420 is not provided at the outer periphery of the third disk body 410. For example, the second notch 413 can be formed by removing material at the outer periphery of the third disk body 410 through various methods such as mechanical cutting and laser cutting.

[0150] It is further understood that the second notch 413 of various shapes can be formed on the outer periphery of the third plate 410, for example, Fig.12 In this case, the second notch 413 is defined by the inner concave edge 415 and the reference line of the outer periphery of the third disk body 410, wherein the reference line can refer to Figures 13 to 17 The dotted line at the second notch 413 in the figure is used for illustration, and the dotted line represents the shape of the third plate 410 when the second notch 413 is not cut out of the third plate 410. The dotted line is obtained by extending the outer periphery of the third plate 410 according to the direction of the original outer periphery. Of course, it is not limited to this, for example, the second notch 413 can be rectangular, fan-shaped, waist-shaped, etc.

[0151] It is understandable that at least one second notch 413 needs to be provided in order to facilitate auxiliary exhaust and auxiliary liquid injection at the outer periphery of the third disk body 410. Of course, in order to further improve the exhaust efficiency and liquid injection efficiency, multiple second notches 413 can be provided. In this case, the arc edge 414 between the multiple second notches 413 also has multiple sections, and accordingly, flanges 420 can be provided on these arc edges 414 respectively. Of course, it is not limited to this. Under the premise of meeting the requirements, the number of second notches 413 and flanges 420 does not need to be provided in a one-to-one correspondence. For example, flanges 420 may not be provided on the arc edges 414 at certain positions.

[0152] like Fig.13As shown, in some embodiments, the number of the arc edge 414, the concave edge 415 and the auxiliary hole 412 are all 4, and the 4 arc edges 414 and the 4 auxiliary holes 412 are arranged one by one, and the midpoints of the corresponding arc edges 414, the centers of the auxiliary holes 412 and the center of the second center hole 411 are collinear. It can be understood that, in this way, along the radial direction of the third disk body 410, the auxiliary holes 412 and the second notches 413 are staggered with each other. By making the number of the arc edge 414, the concave edge 415 and the auxiliary hole 412 correspond to each other and setting them to 4, it is beneficial to balance the liquid injection and exhaust effect of the third disk body 410 and the welding effect of the flange 420 and the shell 100. At the same time, the second center hole 411, the auxiliary hole 412 and the arc edge 414 are set to be collinear, so as to avoid the weakening of the structural strength of the third disk body 410 caused by the auxiliary hole 412, the second notch 413 and the second center hole 411 being collinear, which can effectively ensure the structural strength of the third disk body 410 and at the same time ensure the weldable area between the third disk body 410 and the core 300.

[0153] Furthermore, if Fig.12 As shown, the auxiliary hole 412 is waist-shaped, that is, the auxiliary hole 412 is a waist-shaped hole, and its long axis direction is consistent with the radius direction of the third disk body 410. It can be understood that for a large cylindrical battery, the disk surface of the negative electrode current collector 400 is also large. The auxiliary hole 412 is a waist-shaped hole and its long axis direction is set to extend along the radius direction of the third disk body 410. Without affecting the welding area, the opening area of ​​the auxiliary hole 412 can be effectively increased, thereby improving the auxiliary liquid injection effect.

[0154] like Fig.13 and Fig.14 As shown, in some embodiments, the area of ​​the third plate 410 is S4a, the total area of ​​the second notch 413 is S4b, and the range of S4b / S4a is 2% to 10%, that is, 2%≤S4b / S4a≤10%. For example, S4a is 1604.6 mm 2 , S4b is 95.56mm 2 , S4b / S4a is 5.96%. Fig.13 As shown, the area S4a of the third plate body 410 refers to the plate surface area of ​​the third plate body 410, that is, the area of ​​the third plate body 410 when the second center hole 411, the auxiliary hole 412, and the second notch 413 are not provided. Fig.14As shown, the total area of ​​the second notch 413 is S4b, which is the sum of the areas of the closed figure defined by the concave edge 415 and the reference line (dashed line in the figure) of the outer periphery of the third disk body 410. It can be further understood that, for a single second notch 413, its area refers to the area defined by the outer periphery edge line of the third disk body 410 as the reference line and the boundary line of the second notch 413 itself, i.e., the concave edge 415.

[0155] It is understandable that if the total area S4b of the second notch 413 is too small, on the one hand, during the injection process, the second notch 413 does not significantly improve the injection efficiency, and there is also a risk of electrolyte overflow, which causes the outer surface of the shell 100 to be contaminated by the electrolyte, rust, and even the battery is scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the second notch 413, and the effect of improving battery safety is limited. On the contrary, if the total area S4b of the second notch 413 is too large, the second notch 413 will occupy the welding area on the disk surface of the third disk 410, resulting in a reduction in the actual effective welding area between the third disk 410 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in the welding area will lead to an increase in the internal resistance of the battery. By setting the range of S4b / S4a to 2% to 10%, it is possible to ensure good welding effect between the third disk 410 and the winding core 300 while taking into account the injection efficiency and exhaust efficiency of the third disk 410, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0156] As mentioned above, in this embodiment, a second central hole 411 is provided on the third plate 410. The second central hole 411 is provided at the center of the third plate 410 and is used to inject electrolyte into the battery. It should be noted that the center of the third plate 410 may be the center of the circle of the third plate 410. Figure 1 It is understood that the winding core 300 is made by a winding process, and a circular winding core hole 330 is formed at the center of the winding core 300 after winding. To match the shape of the winding core hole 330, the shape of the second center hole 411 is preferably circular. In this case, the second center hole 411 is co-centered with the third disk 410. It is understood that the diameter of the second center hole 411 can be specifically selected according to the balance between the injection efficiency and the weldable area.

[0157] Furthermore, if Fig.13 and Fig.15As shown, in some embodiments, the area of ​​the second center hole 411 is S4c, and the range of S4c / S4a is 1% to 3%, that is, 1%≤S4c / S4a≤3%. For example, the area of ​​the second center hole 411 is 28.27mm 2 , S4a is 1604.6mm 2 , S4c / S4a is 1.76%. The second center hole 411 is located at the center of the third disk body 410, and the number thereof is 1. Therefore, the area S4c of the second center hole 411 here only refers to the area of ​​the second center hole 411 itself.

[0158] It is understandable that if the area S4c of the second center hole 411 is too small, on the one hand, during the injection process, due to the narrow injection channel, the electrolyte is difficult to be injected into the battery, and the injection time increases, which will lead to a decrease in the injection efficiency; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the second center hole 411, which reduces the safety of the battery. On the contrary, if the area S4c of the second center hole 411 is too large, the second center hole 411 will occupy the welding area on the disk surface of the third disk body 410, resulting in a reduction in the actual effective welding area between the third disk body 410 and the negative terminal 220, and the current capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety issues such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance value of the battery. By setting the range of S4c / S4a to 1% to 3%, it is possible to take into account the injection efficiency and exhaust efficiency of the negative electrode current collecting disk 400 while ensuring a good welding effect between the third disk body 410 and the winding core 300, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0159] As mentioned above, in this embodiment, the third plate body 410 is provided with a through auxiliary hole 412, which is provided at the periphery of the second central hole 411 to assist in the injection of electrolyte. It is understood that the size of the auxiliary hole 412 can be specifically selected based on the balance between the injection efficiency and the weldable area.

[0160] Furthermore, if Fig.13 and Fig.16 As shown, in some embodiments, the total area of ​​the auxiliary holes 412 is S4d, and the range of S4d / S4a is 9% to 21%, that is, 9%≤S4d / S4a≤21%. For example, the total area of ​​the auxiliary holes 412 is 226.27 mm 2 , S4a is 1604.6mm 2 , S4d / S4a is 14.1%. The total area S4d of the auxiliary holes 412 refers to the sum of the areas of all the auxiliary holes 412 on the third plate 410 .

[0161] It is understandable that if the total area S4d of the auxiliary holes 412 is too small, on the one hand, during the injection process, the injection time increases, which will lead to a decrease in the injection efficiency, and there will also be a risk of electrolyte overflow, which will cause the outer surface of the shell 100 to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the auxiliary holes 412, and the effect of improving battery safety is limited. On the contrary, if the total area S4d of the auxiliary holes 412 is too large, the auxiliary holes 412 will occupy the welding area on the disk surface of the third disk 410, resulting in a reduction in the welding area between the third disk 410 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in the welding area will lead to an increase in the internal resistance value of the battery. By setting the range of S4d / S4a to 9% to 21%, it is possible to ensure good welding effect between the third disk body 410 and the winding core 300 while taking into account the injection efficiency and exhaust efficiency of the negative electrode current collecting disk 400, and also effectively avoid increasing the internal resistance of the battery.

[0162] As mentioned above, the shape of the third disk body 410 is a closed figure composed of multiple arc edges 414 and multiple concave edges 415 that are alternately connected end to end, so that the outer periphery of the third disk body 410 includes multiple arc edges 414 that are disconnected from each other. As mentioned above, the two ends of each arc edge 414 can be extended to connect to each other to form a complete circle. Therefore, the third disk body 410 can be regarded as a circular component. Therefore, it can be understood that these arc edges 414 themselves are partial arc segments of a complete circle, and multiple flanges 420 are arranged on these arc edges 414 one by one, and each flange 420 extends along the edge of the arc edge 414, so that each flange 420 is also in an arc shape. It should be noted that the arc length of the flange 420 can be less than the arc length of the arc edge 414. In this case, the second notch 413 and the flange 420 are not directly connected.

[0163] In some embodiments, Fig.17 As shown, the circumference of the third plate 410 is H4a, the total arc length of the flange 420 is H4b, and the range of H4b / H4a is 42% to 58%, that is, 42%≤H4b / H4a≤58%. For example, the circumference H4a of the third plate 410 is 142mm, the total arc length H4b of the flange 420 is 70.68mm, and H4b / H4a is 49.77%. Among them, the circumference of the third plate 410 H4a refers to the circumference of the complete circular figure where the arc edge 414 is located, that is, Fig.13The perimeter of the outer contour of the middle shaded area, and the total arc length of the flange 420 is H4b, which refers to the sum of the arc lengths of multiple flanges 420 ( Fig.17 Only the arc length of one section of the flange 420 is marked), for example, the third plate 410 is provided with a total of 4 sections of flanges 420, and the arc length of each section is 17.67 mm, then the total arc length H4b of the flange 420 is 70.68 mm.

[0164] It is understandable that when the flange 420 is welded to the shell 100, since the clamping tooling will occupy part of the flange 420, if the total arc length H4b of the flange 420 is too small, it will be difficult to position, and it will also affect the actual welding area, so that the effective welding area is reduced, which will lead to a decrease in the current capacity of the welding point, and the problem of excessive temperature rise will occur in subsequent use, and the internal resistance will be increased, thereby affecting the battery performance. On the contrary, if the total arc length H4b of the flange 420 is too large, the weight of the negative electrode collector 400 will be increased, thereby reducing the energy density of the battery, and it will also cause the welding wire to be too long, and the excessively long welding wire will not only not reduce the resistance of the battery, but will reduce the reliability of the welding, for example, it will increase the risk of leakage, cold welding, and leaking welding at the welding point, which may increase the internal resistance of the battery. By setting the range of H4b / H4a to 42% to 58%, it is possible to ensure a good welding effect between the flange 420 and the shell 100 while ensuring that the negative electrode collector 400 is lighter, thereby improving the energy density of the battery and effectively avoiding an increase in the internal resistance of the battery.

[0165] In some embodiments, Fig.17 As shown, the circumference of the third plate 410 is H4a, the total arc length of the second notch 413 is H4c, and the range of H4c / H4a is 25% to 38%, that is, 25%≤H4c / H4a≤38%. For example, the circumference of the third plate 410 is H4a, which is 142 mm, and the total arc length of the second notch 413 is H4c, which is 45.32 mm, and H4c / H4a is 31.92%. Among them, the circumference of the third plate 410 is H4a, which refers to the circumference of the complete circular figure where the arc edge 414 is located, that is, Fig.13 The circumference of the outer contour of the middle shaded area, and the total arc length H4c of the second notch 413 refers to the arc length after the arc length of all arcs along the edge 414 is removed from the circumference of the third plate 410, that is, Fig.17 The sum of the arc lengths of the dashed lines in ( Fig.17 Only the arc length of a dotted line is marked in the figure), for example, the third plate body 410 is provided with a total of 4 second notches 413, and the arc length of each single second notch 413 is 11.33 mm, then the total arc length H4c of the second notches 413 is 45.32 mm.

[0166] It is understandable that if the total arc length H4c of the second notch 413 is too short, on the one hand, during the injection process, the injection time increases, which will lead to a decrease in the injection efficiency, and there will also be a risk of electrolyte overflow, thereby causing the outer surface of the shell 100 to be contaminated by the electrolyte, rust, and even the battery to be scrapped, and it is also necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost; on the other hand, when the battery is short-circuited or other thermal runaway conditions occur during use, the gas generated inside the battery cannot be discharged in time through the second notch 413, and the effect of improving the safety of the battery is limited. On the contrary, if the total arc length H4c of the second notch 413 is too long, the second notch 413 will occupy the welding area on the disk surface of the third disk 410, resulting in a reduction in the actual effective welding area between the third disk 410 and the negative terminal 220, and the overcurrent capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety problems such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance value of the battery. By setting the range of H4c / H4a to 25% to 38%, it is possible to ensure good welding effect between the third disk body 410 and the winding core 300 while taking into account the injection efficiency and exhaust efficiency of the negative electrode current collecting disk 400, and also effectively avoid increasing the internal resistance of the battery.

[0167] In some embodiments, Fig.17 As shown, the maximum depth H4d of the second notch 413 is in the range of 2 to 5 mm, that is, 2 mm ≤ H4d ≤ 5 mm. It should be noted that the maximum depth H4d of the second notch 413 refers to the distance from the highest point of the reference line of the outer periphery of the third disk body 410 to the deepest point of the second notch 413. For example, Fig.17 The shape of the concave edge 415 shown in the figure is an arc, and its deepest point is at the midpoint of the arc-shaped concave edge 415, and the highest point of the reference line of the outer periphery of the third disk body 410 is at the midpoint of the dotted line. Therefore, in this case, the maximum depth H4d is the distance between the midpoint of the concave edge 415 and the midpoint of the dotted line.

[0168] It is understandable that if the maximum depth H4d of the second notch 413 is too small, that is, the depth of the second notch 413 is too shallow, the area of ​​the second notch 413 will be smaller, and the channel formed by the second notch 413 and the shell 100 will be narrow. On the one hand, during the injection process, the second notch 413 does not significantly improve the injection efficiency, and there is still a risk of electrolyte overflow, which causes the outer surface of the shell 100 to be contaminated by the electrolyte, rust, and even the battery is scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase manufacturing costs. On the other hand, when a short circuit or other thermal runaway occurs during use of the battery, the gas generated inside the battery cannot be discharged in time through the second notch 413, and the effect on improving battery safety is limited. On the contrary, if the maximum depth H4d of the second notch 413 is too large, that is, the depth of the second notch 413 is too deep, the second notch 413 will occupy the welding area on the disk surface of the third disk 410, resulting in a reduction in the actual effective welding area between the third disk 410 and the negative terminal 220, and the current capacity of the welding position does not meet the requirements, thereby causing excessive overcurrent temperature rise, causing subsequent safety issues such as thermal control, and the safety performance of the battery is reduced. In addition, the reduction in welding area will lead to an increase in the internal resistance of the battery. By setting the maximum depth H4d of the second notch 413 in the range of 2 to 5 mm, it is possible to ensure a good welding effect between the third disk 410 and the winding core 300 while taking into account the injection efficiency and exhaust efficiency of the third disk 410, and it is also possible to effectively avoid increasing the internal resistance of the battery.

[0169] like Fig.17 As shown, in some embodiments, the second center hole 411 and the arc edge 414 are arranged co-centrically, the radius of the third plate 410 is L4a, the distance between the inner edge of the auxiliary hole 412 and the center of the second center hole 411 is L4b, and the range of L4b / L4a is 18% to 36%, that is, 18%≤L4b / L4a≤36%. For example, L4a is 22.6 mm, L4b is 6 mm, and L4b / L4a is 26.55%.

[0170] It can be understood that the size of the cylindrical lithium-ion battery is basically fixed, that is, the shell diameter of the cylindrical lithium-ion battery is determined, so the diameter of the third disk body 410 of the negative electrode current collector 400 assembled into the shell is basically determined, and because the second center hole 411 is located at the center of the third disk body 410, if L4b / L4a is too small, the auxiliary hole 412 and the second center hole 411 are too close. In this way, the structural strength of the connecting part between the auxiliary hole 412 and the second center hole 411 may be insufficient, and there is a risk of breaking. Moreover, once this part is broken, metal chips will be generated, and the burrs generated at the fracture are also easy to deform inward and pierce the diaphragm. Both metal chips and burrs may cause short circuit failure of the battery, posing a safety risk. On the contrary, if L4b / L4a is too large, the auxiliary hole 412 is too far from the second center hole 411. In this way, when the electrolyte is injected through the second center hole 411, when the second center hole 411 cannot meet the injection speed requirement, the time for the electrolyte to spread through the disk surface of the third disk body 410 to the auxiliary hole 412 will increase, and during the electrolyte spreading process, the electrolyte will continue to be injected into the battery, which is easy to cause overflow, thereby causing the outer surface of the shell 100 to be contaminated by the electrolyte, rust, and even the battery to be scrapped. In addition, it is necessary to increase manpower to deal with the overflow problem, which will increase the manufacturing cost. By setting the range of L4b / L4a to 18% to 36%, it is possible to take into account the structural strength of the connecting part between the second center hole 411 and the auxiliary hole 412 while ensuring the auxiliary injection effect of the auxiliary hole 412.

[0171] The effects of the present application are further described below with specific examples and comparative examples.

[0172] Embodiment 1:

[0173] Embodiment 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector disc 400, and the negative electrode current collector disc 400 includes a third disc body 410 and four flanges 420 protruding from the outer periphery of the third disc body 410. One side of the third disc body 410 of the negative electrode current collector disc 400 is laser welded to the winding core 300, and the flange 420 is in contact with the shell wall of the shell 100 in the direction away from the winding core 300, and the two are connected by laser through-welding. The third disc body 410 is provided with a second center hole 411 located at the center thereof and four auxiliary holes 412 located on the periphery of the second center hole 411. Four second notches 413 in the shape of an arc are also provided on the outer periphery of the third disc body 410. The midpoints of the edges 414 of each arc, the center of the auxiliary hole 412 and the center of the second center hole 411 are collinear, and the negative electrode current collector disc 400 also meets the following parameters:

[0174] The area S4a of the third plate 410 is 1604.6 mm 2 The total area S4b of the second notch 413 is 95.56mm 2The area S4c of the second center hole 411 is 28.27mm 2 The total area S4d of the auxiliary hole 412 is 226.27mm 2 ; The circumference of the third disk body 410 is H4a, which is 142mm; the total arc length H4b of the flange 420 is 70.68mm; the total arc length H4c of the second notch 413 is 45.32mm; the depth H4d of the second notch 413 is 3mm; the radius L4a of the arc edge 414 (third disk body 410) is 22.6mm; the distance L4b from the innermost side of the auxiliary hole 412 to the center position of the second center hole 411 is 6mm.

[0175] From the above, it can be seen that in the negative electrode current collecting plate 400, S4b / S4a=6%, S4c / S4a=2%, S4d / S4a=14%, H4b / H4a=50%, H4c / H4a=32%, and L4b / L4a=27%.

[0176] Embodiment 2:

[0177] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 400, which differs from Example 1 in that: S4b / S4a=4%, S4d / S4a=16%, H4b / H4a=54%, H4c / H4a=29%, H4d=2mm, L4b / L4a=24%.

[0178] Embodiment 3:

[0179] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 400, which differs from Example 1 in that: S4b / S4a=8%, S4d / S4a=12%, H4b / H4a=46%, H4c / H4a=33%, H4d=4mm, L4b / L4a=30%.

[0180] Comparative Example 1:

[0181] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , which is different from Example 1 in that: S4b / S4a=1%, H4c / H4a=14.8%, and H4d=0.9 mm.

[0182] Comparative Example 2:

[0183] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, which is different from Example 1 in that: S4b / S4a=15%, H4c / H4a=41%, and H4d=5.83 mm.

[0184] Comparative Example 3:

[0185] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between Comparative Example 3 and Example 1 is that S4d / S4a=5%.

[0186] Comparative Example 4:

[0187] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between the comparative example 4 and the embodiment 1 is that S4d / S4a=25%.

[0188] Comparative Example 5:

[0189] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 5 and the embodiment 1 is that S4c / S4a=0.5%.

[0190] Comparative Example 6:

[0191] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 6 and the embodiment 1 is that S4c / S4a=8%.

[0192] Comparative Example 7:

[0193] Comparative Example 7 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 7 and the embodiment 1 is that L4b / L4a=12%.

[0194] Comparative Example 8:

[0195] Comparative Example 8 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between the comparative example 8 and the embodiment 1 is that L4b / L4a=46%.

[0196] Comparative Example 9:

[0197] Comparative Example 9 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between Comparative Example 9 and Example 1 is that H4b / H4a=35%.

[0198] Comparative Example 10:

[0199] Comparative Example 10 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between Comparative Example 10 and Example 1 is that H4b / H4a=68%.

[0200] Comparative Example 11:

[0201] Comparative Example 11 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 1 and the embodiment 1 is that S4b / S4a=4.1%, H4c / H4a=20%.

[0202] Comparative Example 12:

[0203] Comparative Example 12 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 1 and the embodiment 1 is that S4b / S4a=8.3%, H4c / H4a=45%.

[0204] Comparative Example 13:

[0205] Comparative Example 13 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 1 and the embodiment 1 is that S4b / S4a=2.6%, H4d=1.25mm.

[0206] Comparative Example 14:

[0207] Comparative Example 14 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 1 and the embodiment 1 is that S4b / S4a=14.8%, H4d=6.5mm.

[0208] Table 2 below evaluates the negative electrode current collector disc 400 manufactured in the above embodiment and comparative example in terms of the number of folding times (C) at which the third disc body breaks after being folded, the time required for the electrolyte to be injected into the battery (t), the maximum welding temperature (TMax) between the third disc body and the winding core, and the battery internal resistance (R). Among them:

[0209] The specific test method for the number of folding times (C) when the third plate body breaks after being folded is as follows: take the negative electrode current collector plate 400, cut the connection between the third plate body 410 and the flange 420 with scissors, remove the flange 420, fold and unfold once along the line connecting the auxiliary hole 412 of the third plate body 410 and the second center hole 411, repeat several times until the connection part between the second notch 413 and the second center hole 411 is completely broken, and stop, and record the number of folding times. Among them, each side folding requires that the two half surfaces are completely fitted together, and then opened to 180° after folding.

[0210] The specific test method for the time (t) required for the electrolyte to be injected into the battery is as follows: the negative electrode current collecting plate 400 manufactured in the above-mentioned embodiment and comparative example is installed into the battery, and the normal battery cell manufacturing process is followed to the grooving process and then to the liquid injection stage, 75g of electrolyte is injected into the liquid holding cup, and the liquid holding cup is pressed into the groove of the groove, and the sealing ring under the liquid holding cup is completely pressed against the deep end surface of the groove, and then the liquid is injected, and the negative pressure in the liquid holding cup is firstly pumped to -90KPa, and the electrolyte can be observed from the liquid holding cup. The electrolyte height drops, and the electrolyte flows into the battery. After maintaining for 40 seconds, it is switched to positive pressure injection. Nitrogen is filled into the battery to gradually turn the inside of the battery into a positive pressure of 0.8 MPa. The electrolyte in the liquid holding cup continues to flow into the battery, and the electrolyte height in the liquid holding cup gradually drops. Then it is adjusted to negative pressure injection, and the positive and negative pressure injections are repeated until the electrolyte in the liquid holding cup completely flows into the battery, and the time taken for the electrolyte height in the liquid holding cup to drop to 0 is recorded.

[0211] The specific test method for the maximum temperature (TMax) of the weld mark between the third disk and the winding core is as follows: the negative electrode current collector disk 400 manufactured in the above-mentioned embodiment and the comparative example is assembled into an experimental cylindrical lithium-ion battery, a through hole with a diameter of 3 mm is drilled on the negative electrode cover plate 600 of the experimental cylindrical lithium-ion battery, the temperature control line is passed through the through hole, and is attached to the weld mark of the negative electrode current collector disk 400 and the negative end 220 of the winding core 300, and the negative electrode cover plate 600 is sealed after liquid injection according to the normal sample preparation process, and the battery is divided into different capacities to make a qualified cylindrical lithium-ion battery, and 10 cycles of charge and discharge are performed at a high rate of 3C. After 10 cycles of charge and discharge, the temperature data of the welding area collected by the temperature control line is obtained, and the maximum value Tmax within the temperature fluctuation range within 10 cycles is taken and recorded.

[0212] The specific test method for the internal resistance (R) of the battery is as follows: the negative electrode current collecting disc 400 and the winding core 300 manufactured in the above-mentioned embodiments and comparative examples are welded and then placed in the shell 100, and the welding is performed according to the normal process. The batteries all adopt a ternary high-nickel system, and the ratio, electrolyte, positive and negative electrode formula, and material selection are all kept consistent. The flange 420 of the negative electrode current collecting disc 400 is penetrated and welded with the shell wall of the shell 100. The welding parameters are: welding focal length 0, welding speed 160mm / s, welding power 330W, and a weld mark with a width of 0.6mm is welded along the arc length of the flange 420, and then the subsequent liquid filling and sealing are carried out, and the capacity is divided. After the qualified cylindrical lithium-ion battery is made, its internal resistance is tested offline.

[0213] Table 2

[0214]

[0215]

[0216] As shown in Table 2, the range of S4b / S4a is set at 2% to 10%, the range of S4c / S4a is set at 1% to 3%, the range of S4d / S4a is set at 9% to 21%, the range of H4b / H4a is set at 42% to 58%, the range of H4c / H4a is set at 25% to 38%, the range of H4d is set at 2 to 5mm, the range of L4b / L4a is set at 18% to 36%, the injection time is usually 705 to 708 seconds, the number of folding times is usually 11 times, and the maximum temperature rise at the welding position is 117° to 118°, and the internal resistance of the battery is 2.7mΩ. It can be seen that within the above numerical range, the structural strength, injection rate, welding temperature rise and welding internal resistance of the negative electrode collector can be well balanced, thereby effectively improving the safety and charge and discharge performance of the battery, and reducing the production cost of the battery.

[0217] As can be seen from Table 2, if S4b / S4a is too large (increasing the depth of the second notch 413 and increasing the arc length of the second notch 413), although the injection rate can be increased, the temperature rise of the welding position between the third disk 410 and the winding core 300 will increase significantly, and the internal resistance of the battery will increase; on the contrary, if S4b / S4a is too small, the injection rate will decrease. Therefore, setting S4b / S4a within a reasonable range can balance the injection rate, welding temperature rise and internal resistance of the negative electrode current collector 400.

[0218] As can be seen from Table 2, if S4c / S4a is too large, although the injection rate can be increased, the structural strength of the negative electrode current collector 400 will be reduced to a certain extent, the temperature rise of the welding position between the third disk 410 and the winding core 300 will also increase, and the internal resistance of the battery will increase; on the contrary, if S4c / S4a is too small, although the structural strength of the negative electrode current collector 400 can be improved and the internal resistance of the battery and the welding temperature rise can be ensured to be within a reasonable range, the injection rate will be reduced. Therefore, setting S4c / S4a within a reasonable range can balance the structural strength, injection rate, welding temperature rise and internal resistance of the negative electrode current collector 400.

[0219] As can be seen from Table 2, if S4d / S4a is too large, although the injection rate can be increased, the structural strength of the negative electrode current collector 400 will be significantly reduced, the temperature rise of the welding position between the third disc 410 and the winding core 300 will also increase, and the internal resistance of the battery will increase; on the contrary, if S4d / S4a is too small, although the structural strength of the negative electrode current collector 400 can be improved and the internal resistance of the battery and the welding temperature rise can be ensured to be within a reasonable range, the injection rate will be reduced. Therefore, setting S4d / S4a within a reasonable range can balance the structural strength, injection rate, welding temperature rise and internal resistance of the negative electrode current collector 400.

[0220] As can be seen from Table 2, if H4b / H4a is too large or too small, the internal resistance of the battery and the temperature rise of the welding position between the third disk 410 and the winding core 300 will increase to a certain extent. Therefore, setting H4b / H4a within a reasonable range can balance the welding temperature rise of the negative electrode current collecting disk 400 and the internal resistance of the battery.

[0221] It can be seen from Table 2 that, when the maximum depth H4d of the second notch 413 remains unchanged, if H4c / H4a is too large, the opening area of ​​the second notch 413 will become larger. In this way, although the injection rate can be increased, the temperature rise of the welding position between the third disk 410 and the winding core 300 will increase to a certain extent, and the internal resistance of the battery will increase; conversely, if H4c / H4a is too small, the opening area of ​​the second notch 413 will become smaller. In this way, although the temperature rise of the welding position between the third disk 410 and the winding core 300 and the internal resistance of the battery can be ensured to be within a reasonable range, the injection rate will be reduced to a certain extent.

[0222] It can be seen from Table 2 that, when the arc length of the second notch 413 remains unchanged, if H4d is too large, the opening area of ​​the second notch 413 will become larger. In this way, although the injection rate can be increased, the temperature rise of the welding position between the third disk 410 and the winding core 300 will increase to a certain extent, and the internal resistance of the battery will increase; on the contrary, if H4d is too small, the opening area of ​​the second notch 413 will become smaller. In this way, although the temperature rise of the welding position between the third disk 410 and the winding core 300 and the internal resistance of the battery can be ensured to be within a reasonable range, the injection rate will be reduced to a certain extent.

[0223] As can be seen from Table 2, if L4b / L4a is too large or too small, the structural strength of the negative electrode current collector 400 will be significantly reduced, and if L4b / L4a is too large, the injection time will be increased to a certain extent, thereby affecting the injection rate. Therefore, setting L4b / L4a within a reasonable range can ensure that the structural strength of the negative electrode current collector 400 meets the requirements while balancing the injection rate.

Claims

1. A cylindrical lithium-ion battery, characterized in that: The invention comprises a shell (100), a positive electrode current collecting disk (200), a winding core (300) and a negative electrode current collecting disk (400) arranged in the shell (100), wherein the shell (100) is provided with a pole (500) on the positive electrode side, and the pole (500) has a liquid injection hole (510) passing through the pole, wherein: The positive electrode current collecting disc (200) comprises a first disc body (210) located at the center and a second disc body (220) connected to the edge of the first disc body (210) and extending radially outward, the first disc body (210) is welded to the pole (500), and a first central hole (211) is provided at the center of the first disc body (210), the first central hole (211) is communicated with the injection hole (510), the second disc body (220) comprises a connecting portion (221) and a welding portion (222) connected to each other, the welding portion (222) is connected to the edge of the first disc body (210) by the connecting portion (221), the connecting portion (221) is provided with a fuse groove (230) at the edge along the length direction thereof, the welding portion (222) is welded to the positive electrode of the winding core (300), and a plurality of first notches (250) are provided at the edge of the second disc body (220); The negative electrode current collecting disc (400) comprises a third disc body (410) and a flange (420) protruding along one side of the outer periphery of the third disc body (410); the third disc body (410) is welded to the negative electrode of the winding core (300); the shape of the third disc body (410) is a closed figure composed of a plurality of circular arc edges (414) and a plurality of concave edges (415) connected alternately end to end; the flange (420) is arranged on the circular arc edge (414 ... ) forms a second notch (413) at the concave edge (415), a second center hole (411) is provided at the center of the third disk body (410), the area of ​​the third disk body (410) is S4a, the total area of ​​the second notch (413) is S4b, the range of S4b / S4a is 2% to 10%, the circumference of the third disk body (410) is H4a, the total arc length of the flange (420) is H4b, and the range of H4b / H4a is 42% to 58%.

2. The cylindrical lithium-ion battery according to claim 1, characterized in that: The area of ​​the first disk body (210) is S2a, the area of ​​the first center hole (211) is S2b, and the range of S2b / S2a is 4.2% to 8.6%; the area of ​​the second center hole (411) is S4c, and the range of S4c / S4a is 1% to 3%.

3. The cylindrical lithium-ion battery according to claim 1, characterized in that: Along the thickness direction of the positive electrode current collector disk, the first disk body (210) is higher than the second disk body (220), and the height difference between the surface of the first disk body (210) on one side higher than the second disk body (220) and the surface of the second disk body (110) on the same side is H2a, and the range of H2a is 0.6 to 1.4 mm; the third disk body (410) is also provided with a plurality of auxiliary holes (412) located on the periphery of the second center hole (411), and the total area of ​​the plurality of auxiliary holes (412) is S4d, and the range of S4d / S4a is 9% to 21%.

4. The cylindrical lithium-ion battery according to claim 1, characterized in that: The connecting portion (221) has a first width W2a, and the connecting portion (221) has a second width W2b in a region where the fuse slot (230) is provided, and the range of W2b / W2a is 42% to 63%; the connecting portion (221) has a first edge (231) extending along a length direction for forming the fuse slot (230), and the length of the first edge (231) is L2a, and the range of L2a is 2 to 4 mm.

5. The cylindrical lithium-ion battery according to any one of claims 1 to 4, characterized in that: The connecting portion (221) comprises: a plurality of first connection portions (2211) arranged at intervals along the circumference of the first disk body (210) and extending radially outward from the edge thereof, wherein the fuse slot (230) is provided at the first connection portion (2211); A second connection portion (2212) formed by extending the outer end portion of each of the first connection portions (2211) toward both sides along the circumferential direction; There are a plurality of welding portions (222), each of which is arranged one by one in a region defined by two adjacent first connecting portions (2211) and the second connecting portions (2212), and is formed by extending radially inwardly from the inner edge of the second connecting portion (2212); The circumference of the third disk (410) is H4a, the total arc length of the second notch (413) is H4c, and the range of H4c / H4a is 25% to 38%.

6. The cylindrical lithium-ion battery according to claim 5, characterized in that: The edges on both sides of the welding portion (222) and the inner edge of the second connecting portion (2212) define a slit (240) extending in the circumferential direction, the circumference of the outer edge of the second connecting portion (2212) is L2b, the total arc length of the slit (240) is L2c, and the range of L2c / L2b is 43% to 58%; the shape of the concave edge (415) is arc-shaped, and the maximum depth of the second notch (413) is H4d, and the range of H4d is 2 to 5 mm.

7. The cylindrical lithium-ion battery according to claim 5, characterized in that: The first notch (250) is arranged on the outer edge of the second connecting portion (2212) at a position corresponding to the welding portion (222); the circumference of the outer edge of the second connecting portion (2212) is L2b; the total arc length of the first notch (250) is L2d; and the range of L2d / L2b is 4% to 9%; the radius of the third disk body (410) is L4a; the third disk body (410) is further provided with a plurality of auxiliary holes (412) located on the outer periphery of the second center hole (411); the distance between the inner edge of the auxiliary hole (412) and the center of the second center hole (411) is L4b; and the range of L4b / L4a is 18% to 36%.

8. The cylindrical lithium-ion battery according to claim 7, characterized in that: The maximum depth of the first notch (250) is L2f, and the range of L2f is 0.9-2.1 mm; the auxiliary hole (412) is a waist-shaped hole, and the long axis direction of the auxiliary hole (412) is consistent with the radius direction of the third disk body (410).

9. The cylindrical lithium-ion battery according to claim 6, characterized in that: The width of the slit (240) in the radial direction is L2e, and the range of L2e is 0.4-1.5 mm; the third disk body (410) and the flange (420) are integrally formed and connected.

10. The cylindrical lithium-ion battery according to claim 5, characterized in that: The second connecting portion (2212) has a radial width W2c in the area corresponding to the slit (240), and the range of W2c is 1 to 3 mm; the third disk body (410) is also provided with an auxiliary hole (412) located on the outer periphery of the second center hole (411), and the number of the arc edge (414), the concave edge (415) and the auxiliary hole (412) is 4, and the 4 arc edges (414) and the 4 auxiliary holes (412) are arranged in a one-to-one correspondence, and the midpoint of the correspondingly arranged arc edges (414), the center of the auxiliary hole (412) and the center of the second center hole (411) are collinear.

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