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, the negative current collecting plate comprises a third plate body and a flange, and the flange is provided with a second center hole. The third disc body comprises a main body part and a plurality of extension parts extending outwards from the main body part in the radial direction, the edges of the extension parts and the edges of the turned-over edges are jointly sunken inwards in a junction area to form first stress release grooves, and the turned-over edges can be bent relative to the third disc body along the first stress release grooves; the extension part is provided with a thinning part extending in the radial direction. When the cylindrical lithium ion battery is assembled, liquid can be selectively injected at the positive electrode side or the negative electrode side, and the cylindrical lithium ion battery also has the characteristics of low manufacturing cost and high reliability and safety.

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, it is difficult for current cylindrical lithium-ion batteries to meet the demand for injection on the positive electrode side.

[0004] The negative electrode collector of a cylindrical lithium-ion battery 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 and connected by penetration welding, so that the shell is conductively connected to the negative electrode of the core. However, if the grooving process is used for sealing on the negative electrode side, after grooving, the material of the shell toward the center of the shell is deformed, pulling the flange of the negative electrode collector to bend together, thereby causing the disk body connected to the flange to also deform in a wavy shape, resulting in the welding point between the disk body of the negative electrode collector and the negative end of the core being pulled or even broken, which directly affects the flow of the overall current of the battery, and the local heat generation at the welding point is too large, causing safety problems.

[0005] In addition, when rolling grooves, the welded flanges are also rolled together, causing the middle of the negative electrode collector disk to bulge, forming an arch bridge shape, as shown. This will tear the weld between the disk surface and the negative end of the winding core, which may cause problems such as tearing of the tab foil or cold welding, affecting the performance 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, insufficient safety and reliability 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 comprises a first disc body located in the center and a second disc body connected to the edge of the first disc body and extending radially outward, the first disc body is welded to the pole, and a first central hole is provided through the center of the first disc body, the first central hole is communicated with the injection hole, the second disc body comprises a connecting portion and a welding portion connected to each other, the welding portion is connected to the edge of the first disc body by the connecting portion, and the connecting portion is provided with a fuse groove at the edge along the length direction thereof;

[0009] The negative electrode current collector disk includes a third disk body and a plurality of flanges protruding toward one side along the outer peripheral edge of the third disk body, the plurality of flanges are in contact with the shell wall of the shell and are welded together, the third disk body includes a main body and a plurality of extensions extending radially outward from the main body, the plurality of flanges are connected one-to-one with the plurality of extensions, and the negative electrode current collector disk is also provided with a first stress release groove at the edge, the first stress release groove is formed by the edge of the extension and the edge of each flange being jointly recessed inwardly at the junction area, the first stress release groove is used for the flange to bend relative to the third disk body along the first stress release groove, and the extension is provided with a thinning portion extending in the radial direction, the thickness of the thinning portion is less than the thickness of other parts of the extension.

[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 a first central hole in the positive current collector, and connecting it to the injection hole located at the pole, the cylindrical lithium-ion battery can be injected on the positive side or the negative side during assembly, so that the injection scheme can be conveniently adjusted according to actual process requirements. In addition, a fuse slot is provided in the positive current collector, which can reduce the width of the connection part. When the current passing through this part is too high, the heat rises and reaches the melting point, so that the connection part is melted at this position, achieving the effect of cutting off the current, so that the positive current collector has a fuse protection function, which can improve the safety of the cylindrical lithium battery.

[0012] Secondly, by setting a first stress release groove on the edge of the negative electrode current collector and a thinning portion on the extension portion, during the grooving process, when the flange is bent relative to the disk body, due to the action of the first stress release groove, the bending occurs near the junction area between the disk body and the flange, and the first stress release groove provides space for material deformation at the bending position, reduces material extrusion or deformation transferred to the disk body or the flange, thereby avoiding problems such as fracture of the welding point caused by pulling and setting, bulging in the middle of the disk surface, etc. due to the deformation of the third disk body and the flange, and the thinning portion has the function of bearing stress. On the basis of the first stress release groove, the thinning portion can play a role in dispersing stress again to avoid deformation of the disk body. Therefore, the cylindrical lithium-ion battery of the application embodiment has high reliability and thus good safety, and also has a good yield rate in the manufacturing process, so that the manufacturing cost is low.

[0013] 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 first stress relief groove is a V-shaped groove, and the V-shaped groove includes an angle α, and the range of α is 30° to 50°.

[0014] In a possible embodiment, along the thickness direction of the positive current collector 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 thinning portion is formed by the two opposite surfaces of the extension portion being recessed inward along the thickness direction, and the thinning portion includes a first transition zone with gradually decreasing thickness, a thickness maintaining zone with unchanged thickness, and a second transition zone with gradually increasing thickness from the inside to the outside in the radial direction, the thickness of the thickness maintaining zone is L4c, the thickness of the main body is L4d, and the range of L4c / L4d is 30% to 60%.

[0015] In a possible implementation, a plurality of first notches are formed at the edge of the second disk; the length of the thickness maintaining area in the radial direction is L4e, the radius of the main body is L4f, and the range of L4e / L4f is 1% to 5%.

[0016] In a possible embodiment, the connecting portion has a first edge extending along the length direction for forming the fuse slot, the length of the first edge is L2a, and the range of L2a is 2 to 4 mm; the arc length of the flange in the circumferential direction is L4a, and the length of the first stress release groove recessed inward in the circumferential direction is L4b, and the range of L4b / L4a is 3% to 10%.

[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 extending the outer end portions of each of the first connection portions 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 negative electrode current collecting disk is further provided with a second stress release groove at the edge, the second stress release groove is formed by the edge of the main body being recessed inwardly, and the edge of the second stress release groove is connected to the edge of the extension portion.

[0022] In a possible embodiment, the edges on both sides of the welding portion and the edges on the inner side 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 total arc length corresponding to the main body at the second stress release groove is L4g, and the total arc length of the main body minus the total arc length corresponding to the extension portion is L4h, and the range of L4g / L4h is 5% to 20%.

[0023] In a possible embodiment, the second disk body is provided with a plurality of first notches, each of the first notches is arranged at the outer edge of the second connecting portion corresponding to the position of the welding portion, the circumference of the outer edge of the second connecting portion is L2b, the total arc length of the first notches is L2d, and the range of L2d / L2b is 4% to 9%; the length of the second stress release groove recessed inward in the radial direction is L4i, the radius of the main body is L4f, and the range of L4i / L4f is 2% to 5%.

[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 bottom of the first stress release groove is located at the junction of the flange and the extension portion.

[0025] In a possible implementation, the width of the slit in the radial direction is L2e, and the range of L2e is 0.4-1.5 mm; the second connecting portion has a width W2c in the radial direction in the area corresponding to the slit, and the range of W2c is 1-3 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 is a cross-sectional schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application;

[0028] Figure 2 It is a structural schematic diagram of a positive electrode current collector provided in an embodiment of the present application;

[0029] Figure 3 yes Figure 2 Schematic diagram of area S2a in the positive electrode current collecting disk;

[0030] Figure 4 yes Figure 2 Schematic diagram of area S2b in the positive electrode current collecting disk;

[0031] Figure 5 yes Figure 3 Schematic cross-sectional view along the AA direction;

[0032] Figure 6 yes Figure 5 The local schematic diagram of point B in the middle;

[0033] Figure 7 yes Figure 1 A schematic top view of the positive electrode current collecting disk in FIG.

[0034] Figure 8 yes Figure 7 The local schematic diagram of the C in the middle;

[0035] Fig. 9 yes Figure 7 The local schematic diagram of point D in the middle;

[0036] Fig.10 It is a schematic diagram of the structure of a negative electrode current collector provided in an embodiment of the present application;

[0037] Fig.11 yes Fig.10 A schematic cross-sectional view of the negative electrode current collector in FIG. 1 when the negative electrode current collector is connected to the housing and is not grooved;

[0038] Fig.12 yes Fig.11 A schematic cross-sectional view of the structure after groove rolling;

[0039] Fig.13 yes Fig.10 The local schematic diagram of the G in the middle;

[0040] Fig.14 yes Fig.13 The local schematic diagram of the H in the middle;

[0041] Fig.15 It is a view of a negative electrode current collector provided by an embodiment of the present application from a side without a flange to a side with a flange;

[0042] Fig.16 yes Fig.15 The local schematic diagram at I in the middle;

[0043] Fig.17 yes Fig.15 The local schematic diagram of the J in the middle;

[0044] Fig.18 is a cross-sectional view of a negative electrode current collector provided in an embodiment of the present application;

[0045] Fig.19 yes Fig.18 Local schematic diagram of point K in the middle. DETAILED DESCRIPTION

[0046] 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 cap 600 , and the like.

[0047] 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 cap 600 is sealed and installed on the negative side of the shell 100 through a rolling groove and sealing process. 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, thereby isolating the winding core 300 and the electrolyte from the external environment, and forming a closed electrochemical system inside the shell 100. 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.

[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 1As 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 2In 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 body 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 body 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 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 for the electrolyte to flow into the winding core 300 through the through-hole structure on the second disc 220 is too long, thereby reducing the injection efficiency, which in turn leads to reduced production efficiency and increased battery manufacturing costs. In addition, there is a high risk of electrolyte overflowing from the injection hole during injection. By setting the range of H2a to 0.6-1.4mm, it is possible to balance battery performance and injection efficiency.

[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, and the difference between the comparative example 1 and the embodiment 1 is 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]

[0133] 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.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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 of the first connection portion 2211 to be broken after being folded at the fuse slot 230 will be reduced.

[0139] 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.

[0140] It can be seen from Table 1 that if H2a is too large, the probability of battery short circuit will increase significantly.

[0141] The negative electrode current collecting disk 400 is described in detail below.

[0142] Fig.10 is a schematic structural diagram of a negative electrode current collecting disc 400 provided in an embodiment of the present application, wherein the negative electrode current collecting disc 400 comprises a third disc body 410 and a plurality of flanges 420 formed by protruding along one side of the outer periphery of the third disc body 410 . Fig.11 yes Fig.10 A cross-sectional diagram of the negative electrode current collector in FIG. 1 when it is connected to the shell and has not been grooved, as shown in FIG. Fig.11 As shown, it can be understood that on the negative electrode side of the cylindrical lithium-ion battery, the third plate body 410 of the negative electrode current collector 400 is connected to the negative electrode of the winding core 300, and the flange 420 is attached to and welded to the shell wall of the cylindrical lithium battery shell 100, wherein the shell wall of the cylindrical lithium battery refers to the inner side wall of the cylindrical lithium battery shell 100, so that the winding core 300 forms a passage between the negative electrode current collector 400 and the shell 100, so that the shell 100 itself serves as the negative electrode of the cylindrical lithium-ion battery. Next, refer to Fig.12 , Fig.12 yes Fig.11 The schematic cross-sectional view of the structure after groove rolling shows that after groove rolling, the shell 100 forms an inwardly recessed groove portion 110 extending in the circumferential direction, and the flange 420 is connected to the shell wall of the groove portion 110 in the shell 100 and is bent and deformed relative to the third disk body 410.

[0143] Specifically, the third disk body 410 is the main structural part of the negative electrode current collector disk 400, which is in the shape of a thin sheet as a whole. The third disk body 410 includes two disk surfaces that are separated from each other, one of which is used to connect with the negative terminal 320 of the winding core 300, specifically by welding, and the other disk surface is open before being sealed. In the subsequent injection process, the electrolyte will enter the winding core 300 through the disk surface on this side. There are multiple flanges 420, that is, the flanges 420 are not a complete circular ring structure. Multiple flanges 420 protrude toward the negative electrode side along the outer periphery of the third disk body 410 in a direction away from the disk surface, for example, protrude at an angle approximately perpendicular to the disk surface, and are arranged at intervals from each other. Multiple flanges 420 increase the welding area between the negative electrode current collector disk 400 and the shell 100 to improve the connection strength between the negative electrode current collector disk 400 and the shell 100. At the same time, due to the increase in welding area, the on-resistance is reduced and the on-current of the battery is increased.

[0144] It is understood that the third plate 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 plate 410 and the flange 420 can be connected as one piece, for example, they can be integrally formed by stamping. It is further understood that the third plate 410 and the flange 420 are integrally formed by a stamping process, which will form a crease at the connection between the plate 100 and the flange 420.

[0145] In this embodiment, the negative electrode current collector 400 is further provided with a first stress release groove 430 at the edge, and the first stress release groove 430 is formed by the edge of the third plate body 410 and the edge of each flange 420 being concave inward at the junction area, and the first stress release groove 430 is used for the flange 420 to bend relative to the third plate body 410 along the first stress release groove 430. It can be understood that the negative electrode current collector 400 has an edge formed on the third plate body 410 and an edge formed on the flange 420, and these edges together constitute the edge of the negative electrode current collector 400, thereby, the first stress release groove 430 is formed on both sides of the connection between each flange 420 and the third plate body 410, such as the two sides of the aforementioned fold, and therefore, for each flange 420, two symmetrically arranged first stress release grooves 430 are formed at its bottom.

[0146] It can be understood that the first stress release groove 430 is a structure formed by the edge of the negative electrode current collecting disk 400 being recessed from the outside to the inside. This structure will cause the material length of the flange 420 and the disk body 100 corresponding to the first stress release groove 430 to become shorter. When the flange 420 is bent relative to the third disk body 410, the first stress release groove 430 can release stress, so that the material in the area between the two first stress release grooves 430 is bent preferentially, that is, the bending occurs at the junction area of ​​the flange 420 and the third disk body 410, such as the crease, thereby avoiding a series of problems caused by the deformation of the third disk body 410 and the flange 420 themselves. Therefore, the first stress release groove 430 is formed by recessing the edge of the third disk body 410 and the edge of each flange 420 inward. During the grooving process, when the flange 420 is bent relative to the third disk body 410, the bending occurs near the junction area between the third disk body 410 and the flange 420 due to the action of the first stress release groove 430. In addition, the first stress release groove 430 provides space for material deformation at the bending position, thereby reducing material extrusion or deformation transmission to the third disk body 410 or the flange 420, thereby avoiding problems such as fracture of welding points caused by pulling and setting, bulging in the middle of the disk surface, etc. due to the deformation of the third disk body 410 and the flange 420.

[0147] As mentioned above, the first stress release groove 430 is formed by the edges of the third plate body 410 and the edges of each flange 420 being concave inward at the junction. Therefore, it can be understood that part of the first stress release groove 430 is set at the flange 420, and part is set on the third plate body 410. Fig.13 , Fig.13 yes Fig.10 A local schematic diagram at point G in the middle, specifically, the flange 420 includes a first edge 421 and a second edge 422 connected to the edge of the third disk body 410, and the edge of the third disk body 410 includes a fifth edge 4122 and a sixth edge 4123 located at the extension portion 412, wherein the fifth edge 4122 is connected to the first edge 421, and the sixth edge 4123 is connected to the second edge 422, thereby, a portion of the first stress release groove 430 is formed by the first edge 421 and the second edge 422 being recessed inwardly toward one end of the third disk body 410, and the other portion is formed by the fifth edge 4122 and the sixth edge 4123 being recessed inwardly at the end connected to the flange 420.

[0148] In order to ensure that the position where the flange 420 is bent relative to the third disk body 410 is exactly located at the junction of the two, in some embodiments, the bottom of the first stress release groove 430 is located at the junction of the flange 420 and the third disk body 410. For example, the negative electrode current collector 400 is formed by stamping, and its flange 420 is formed by bending at the edge of the third disk body 410, and there is a crease between the two, which is the junction of the flange 420 and the third disk body 410. Here, the position of the bottom of the first stress release groove 430 refers to the deepest part of the first stress release groove 430. It can be understood that the bottom of the first stress release groove 430 is at the junction of the flange 420 and the third disk body 410, so that the position where the flange 420 is bent relative to the third disk body 410 is exactly located at the junction of the two, so that when the flange 420 is bent relative to the third disk body 410, the adverse effect of the bending position on the third disk body 410 and the flange 420 is minimized.

[0149] Of course, this is not limited to this. It can be understood that the bottom of the first stress release groove 430 can be set to be biased towards any side of the third disk 410 or the flange 420, so that the flange 420 is bent along the line between the bottoms of the two first stress release grooves 430, so as to more accurately locate the position and direction of the bending, so that the bending can be generated at the required position as much as possible, and the direction of the bending can be controlled.

[0150] For further information, please refer to Fig.15 and Fig.16 , Fig.15 It is a view of the negative electrode current collecting plate 400 from the side without flange to the side with flange 420. Fig.16 yes Fig.15 In the local schematic diagram at I, the arc length of the flange 420 along the circumferential direction of the third disk body 410 is L4a, and the length of the first stress release groove 430 that is recessed inward along the circumferential direction of the third disk body 410 is L4b, and the range of L4b / L4a is 3% to 10%. For example, the range of L4b / L4a can be 3%, 3.8%, 6%, 8% and 10%, etc. In some embodiments, the length of L4b is 0.38mm, and the length of L4a is 10mm. If the range of L4b / L4a is greater than 10%, L4b / L4a is too large, the depth of the V-shaped groove is too deep, and the straight-line distance between the two V-shaped grooves corresponding to the flange 420 is too short, making it easier to deform here, and the degree of deformation cannot be controlled. In addition, the strength of the bend of the flange 420 here is weak, which increases the difficulty of control during production and transportation and during feeding during the process. The flange 420 is easier to deform and bend, making it difficult to determine the tooling as welded to the shell wall, and the problem of cold welding is prone to occur. If the range of L4b / L4a is less than 3%, L4b / L4a is too small, the depth of the V-groove is too shallow, and the guiding effect of the V-groove is greatly reduced.

[0151] For further information, please refer to Fig.13 and Fig.14The first stress release groove 430 is a V-shaped groove, and the V-shaped groove includes a third side 431 and a fourth side 432 forming the V-shaped groove, and the third side 431 and the fourth side 432 form an angle α, and the range of α is 30° to 50°. Specifically, the third side 431 includes a first straight side portion 4311 and a first chamfered portion 4312, and the fourth side 432 includes a second straight side portion 4321 and a second chamfered portion 4322, and the first chamfered portion 4312 is connected to the second chamfered portion 4322, wherein the first straight side portion 4311 and the second straight side portion 4321 form the angle α. It can be understood that the third side 431 includes a first straight side portion 4311 and a first chamfered portion 4312 which are straight segments from outside to inside, and the fourth side 432 includes a second straight side portion 4321 and a second chamfered portion 4322 which are straight segments from outside to inside, and the first chamfered portion 4312 is connected to the second chamfered portion 4322, thereby forming a V-shaped groove. For example, α is 30°, 35°, 40°, 45°, 50°, etc., and is not specifically limited. If α is less than 30°, the angle of α is too small and cannot play a good guiding role. After the flange 420 is welded to the shell 100, when rolling the groove together with the shell 100, the stress concentration is relatively severe. If the angle of the V-shaped groove here is too small, the positioning and bending guiding role is not obvious, and part of the stress cannot be released, resulting in the arching of the middle of the disk surface of the third disk body 410 of the negative electrode collector 400 during the rolling groove; when α is greater than 50°, the angle of α is too large, and the opening angle of the V-shaped groove is too large. In fact, the weld mark of the welding of the negative electrode collector 400 and the shell 100 is usually in the lower middle part and close to the disk surface. If α is too large, it will occupy part of the welding area at both ends, resulting in a smaller welding area, a worse current capacity, an increase in the temperature of the welding area, an increase in the internal resistance of the battery, and an impact on the battery performance. It can be understood that the angle α refers to the angle after the negative electrode collector 400 forms the flange 420 and before the rolling groove process. It can be understood that by providing the first chamfered portion 4312 and the second chamfered portion 4322, stress concentration in the bottom area of ​​the V-shaped groove can be reduced.

[0152] In some embodiments, the shape of the first stress release groove 430 is not limited to a V-shaped groove, and may be, for example, a rectangular groove, a U-shaped groove, etc.

[0153] Further, the first stress release groove 430 is arranged at the junction of the flange 420 and the third disk 410. The first stress release groove 430 is a V-shaped groove. The V-shaped groove includes a third side 431 and a fourth side 432 forming the V-shaped groove. The third side 431 is located at the flange 420, and the fourth side 432 is located at the third disk 410. It can be understood that the groove rolling process will cause the flange 420 to bend, thereby reducing the overall height of the cylindrical lithium-ion battery. If the bending height is lower, the height of the cylindrical lithium-ion battery after the groove rolling is also lower, which helps to improve the unit energy density of the cylindrical lithium-ion battery. The position of the first stress release groove 430 is set at the junction of the flange 420 and the third disk 410, and the bending occurs on the same plane as the third disk 410, which is equivalent to lowering the position where the bending occurs, thereby reducing the height of the cylindrical lithium-ion battery to improve the unit energy density. It can be understood that since the flange 420 protrudes from the edge of the third disk body 410 away from the disk surface, there is a crease between the third disk body 410 and the flange 420. At this time, the bottom of the first stress release groove 430 is located at the crease, that is, the bottom is located both at the extension portion 412 and at the flange 420.

[0154] For further information, please refer to Fig.18 and Fig.19 , Fig.19 yes Fig.18In the local schematic diagram at point K in the middle, the third disk body 410 includes a main body 411 and an extension portion 412 extending radially outward from the main body 411, the number of the extension portions 412 corresponds to the number of the flanges 420, that is, the flanges 420 are connected to the extension portions 412 in a one-to-one correspondence, the extension portion 412 is provided with a thinning portion 4121, the thickness of the thinning portion 4121 is less than the thickness of other parts of the extension portion 412, the extension portion 412 includes a fifth side 4122 and a sixth side 4123 connected to the edge of the main body 411, the thinning portion 4121 extends from the fifth side 4122 to the sixth side 4123, and the aforementioned fourth side 432 is provided on the extension portion 412. By setting the thinning portion 4121, it can be effectively avoided that the flange 420 of the negative electrode collector 400 is subjected to groove rolling after being welded to the shell 100. When the groove rolling depth is too deep, the pulling force of the flange 420 increases, and the flange 420 and even the edge of the disk are pulled and deformed in the axial direction. When the V-shaped groove set at the junction of the flange 420 and the disk has been deformed, and the deformation force is not enough, the thinning portion 4121 plays a secondary effect of relieving stress concentration, and the thinning portion 4121 continues to deform until the required deformation amount is reached. Since the stress is decomposed by the first stress release groove 430 and the thinning portion 4121 respectively, the stress is not concentrated in the center of the disk, so that it will not affect the welding of the disk and the negative side ear of the winding core 300, and the middle part of the disk will not be deformed and arched. The reliability of the welding of the negative electrode collector 400 is guaranteed, and the safety performance of the battery cell is improved. At the same time, by providing the extension portion 412 extending radially outward from the main body 411 , after the negative electrode current collecting disc 400 is inserted into the shell 100 , a gap is left between the shell wall of the shell 100 and the main body 411 , thereby accelerating the injection of electrolyte.

[0155] Furthermore, the thinning portion 4121 extends from the fifth side 4122 along the circumferential direction of the main body 411 to the sixth side 4123, that is, the thinning portion 4121 is radially extended and formed on the extension portion 412, thereby, during the grooving process, the force transmitted by the bending of the flange 420 can be evenly absorbed by the thinning portion 4121.

[0156] Furthermore, the thinning portion 4121 is formed by two opposite surfaces of the extension portion 412 being recessed inwardly along the thickness direction of the extension portion 412, and the thinning portion 4121 includes a first transition zone 4121a with a gradually decreasing thickness, a thickness-maintaining zone 4121b with a constant thickness, and a second transition zone 4121c with a gradually increasing thickness along the radial outward direction of the main body portion 411. Fig.19As shown, the thickness of the thickness-maintaining area 4121b is L4c, the thickness of the main body 411 is L4d, and the range of L4c / L4d is 30% to 60%. For example, the range of L4c / L4d can be 30%, 35%, 40%, 45%, 50%, 55% and 60%, without specific limitation. In some embodiments, the thickness L4c of the thickness-maintaining area 4121b is 0.1mm, the thickness L4d of the main body 411 is 0.2mm, and the ratio of L4c / L4d is 50%. When L4c / L4d is less than 30%, the thickness of the thinned portion 4121 is too thick. During the groove rolling process of the negative electrode current collecting disk 400, when the groove depth pulls the flange 420, the thinned portion 4121 cannot play a good role in relieving stress, and most of the stress is concentrated at the junction of the flange 420 and the extension portion 412 and cannot be released and decomposed, then the middle of the disk surface is prone to arching, causing the foil to tear at the laser welding point between the disk surface and the negative electrode side of the winding core 300, resulting in problems such as cold welding and poor contact. The current-carrying capacity of the welding point is insufficient, causing the temperature to rise in a short time during overcurrent, affecting the performance of the battery cell, reducing the safety factor of the battery cell, and making it easy to have risks such as thermal runaway. When L4c / L4d>60%, the thickness of the thinned portion 4121 is too thin, and the negative electrode current collector 400 pulls the flange 420 during the groove rolling process, causing the thinned portion 4121 to be severely deformed, insufficient in strength, and unable to be processed. The thinned portion 4121 is at risk of breaking, causing the failure of the battery cell, increasing the difficulty of the battery cell process, and increasing the manufacturing cost of the battery cell. The first transition zone 4121a and the second transition zone 4121c are set to achieve smooth thinning of the thinned portion 4121, reduce stress concentration of the extension portion 412 and the thickness retention zone 4121b, and increase the overall structural strength of the thinned portion 4121 through smooth thinning, avoiding the thinned portion 4121 from breaking during the transportation and processing of the negative electrode current collector 400.

[0157] Furthermore, the thickness variation slopes of the first transition zone 4121 a and the second transition zone 4121 c are the same, which facilitates the manufacture of the thinning portion 4121 .

[0158] In some embodiments, the first transition zone 4121a and the second transition zone 4121c may not be provided, or only one of the first transition zone 4121a and the second transition zone 4121c may be provided, thereby saving the manufacturing process of the thinning portion 4121.

[0159] In some embodiments, the length of the thickness maintaining area 4121b of the thinning portion 4121 along the radial direction of the disk main body 411 is L4e, the radius of the main body 411 is L4f, and the range of L4e / L4f is 1% to 5%. For example, the ratio of L4e / L4f can be 1%, 1.2%, 2%, 3%, 4%, and 5%, etc., and is not specifically limited. For example, the length of L4e is 0.23mm, and the radius of the main body 411 is 19.7mm, then L4e / L4f is 1.2%. When L4e / L4f is less than 1%, the width of the thinning portion 4121 is too narrow. When rolling the groove, the groove depth is deep, and the thinning portion 4121, which plays a secondary protection role, begins to deform and bend. However, bending has a certain bending radius to achieve the bending function. At this time, the width of the thinning portion 4121 is too narrow, and the bending deformation cannot be completed directly in the thinning portion 4121 during the secondary bending. The disk surface of normal thickness around the thinning portion 4121 needs to be deformed. At this time, the thickness of the deformation area will be inconsistent, resulting in uneven stress dispersion, increased bending difficulty, difficult process, reduced battery output, and increased manufacturing cost of the corresponding battery. When L4e / L4f is greater than 5%, the width of the thinning portion 4121 is too wide, the structural strength decreases, the flatness of the entire disk surface is difficult to control, the manufacturing difficulty increases, and the process of shaping flatness needs to be added later. Adding processes increases the investment cost of manpower and equipment, and the manufacturing cost increases.

[0160] Furthermore, if Fig.15 , Fig.16 and Fig.17 As shown, the negative electrode current collector 400 is further provided with a second stress release groove 4111 at the edge, and the second stress release groove 4111 is formed by the inner depression of the edge of the main body 411 located on both sides of the extension part 412, and the edge of the second stress release groove 4111 is connected to the edge of the extension part 412. By providing the second stress release groove 4111, the stress is transferred from the flange 420 to the thinning part 4121 through the extension part 412, and then to the second stress release groove 4111. At this time, the second stress release groove 4111 serves as the third stress relief structure, and the second stress release groove 4111 further relieves the stress caused by the bending of the flange 420 during the groove rolling process, so that the stress on the main body 411 is greatly reduced, and the structural deformation of the main body 411 is avoided.

[0161] It is understandable that for the location of a single extension portion 412, there is a pair of second stress release grooves 4111, and the two second stress release grooves 4111 are respectively arranged in the area connected to the extension portion 412 on the main body 411, which is conducive to dispersing stress and further ensuring that the structure of the main body 411 is not deformed. Furthermore, the shape of the second stress release groove 4111 is arc-shaped, which is conducive to avoiding stress concentration.

[0162] Furthermore, if Fig.17 As shown, Fig.17 yes Fig.15 In the partial schematic diagram at J in the middle, the main body 411 is provided with a plurality of second stress release grooves 4111 and a plurality of extensions 412. The total arc length of the main body 411 at the second stress release grooves 4111 is L4g, and the length of the total arc length of the main body 411 minus the total arc length corresponding to the extensions 412 is L4h. The range of L4g / L4h is 5% to 20%, for example, the ratio of L4g / L4h can be 5%, 7%, 10%, 12%, 15%, 17% and 20%. The arc length L4g of the main body 411 at the second stress release grooves 4111 is the total arc length of all the second stress release grooves 4111, and L4h is the total arc length of the main body 411 minus the arc length corresponding to the plurality of extensions 412. Fig.15 and Fig.17 Only a section of the arc length L4g of the second stress release groove 4111 and only a section L4h are marked. When L4g / L4h is less than 5%, the arc length is too small, and the second stress release groove 4111 structure for relieving stress concentration cannot effectively decompose stress, resulting in some stress still being concentrated on the disk surface of the main body 411, resulting in a certain height of arching and deformation in the middle of the disk surface after rolling, and when the electrolyte flows into the battery cell through the through hole of the disk surface, the arc of the second stress release groove 4111 of the disk surface is too small, resulting in a slow electrolyte diversion speed, thereby reducing the injection efficiency, increasing the injection time, and increasing the manufacturing cost; if L4g / L4h>20%, the arc length is too long, the structural strength of the second stress release groove 4111 will be reduced, and the second stress release groove 4111 is easy to deform. During the process and transportation, the difficulty of control in the process increases. During transportation, it is easy to cause deformation here due to bumps, bumps, etc., and when the flange 420 is welded to the shell 100, the problem of cold welding is easy to occur. In some embodiments, L4g is 8.4 mm, L4h is 69.84 mm, and the ratio of L4g / L4h is 12%.

[0163] Furthermore, the inward recessed length of the second stress release groove 4111 in the radial direction of the main body 411 is L4i, the radius of the main body 411 is L4f, and the range of L4i / L4f is 2% to 5%. For example, the ratio of L4i / L4f can be 2%, 3%, 4% and 5%. When L4i / L4f is less than 2%, the depth of the second stress release groove 4111 is too shallow. As the third stress concentration relief protection structure, the second stress release groove 4111 cannot effectively decompose stress, resulting in some stress still being concentrated on the disk surface. After the groove is rolled, the middle of the disk surface will have a certain height of arching and deformation, and when the electrolyte flows into the battery cell through the through hole of the disk surface, the depth of the second stress release groove 4111 of the disk surface is too shallow, resulting in the electrolyte shunt speed being slowed down, thereby reducing the injection efficiency, increasing the injection time, and increasing the manufacturing cost; when L4i / L4f is greater than 5%, the depth of the second stress release groove 4111 is too deep, which will occupy the welding area on the negative side of the disk surface and the winding core 300, resulting in a smaller welding area, a poorer current capacity at the welding point, and an increased temperature rise of the welding, which affects the battery performance. In some embodiments, L4i is 0.68mm, L4f is 19.7mm, and the ratio of L4i / L4f is 3%.

[0164] Furthermore, the main body 411 is also provided with a second center hole 4112 located at its center and a plurality of auxiliary holes 4113 located on the periphery of the second center hole 4112, and the second center hole 4112 and the plurality of auxiliary holes 4113 are used to inject electrolyte into the battery. In order to match the shape of the hole of the winding core 300, the shape of the second center hole 4112 is preferably circular, in which case the second center hole 4112 is co-centered with the main body 411. It is understood that the diameter of the second center hole 4112 can be specifically selected based on the balance between the injection efficiency and the weldable area. The size of the auxiliary hole 4113 can be specifically selected based on the balance between the injection efficiency and the weldable area. Furthermore, the auxiliary hole 4113 is in the shape of a waist-shaped hole, and the number is 4. The combined figure of the four auxiliary holes 4113 is a central symmetrical figure, and the center of symmetry is the center of the second center hole 4112, so as to ensure uniformity during electrolyte injection.

[0165] The effects of the present application are further described below with specific examples and comparative examples.

[0166] Embodiment 1:

[0167] Embodiment 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector disc 400, the negative electrode current collector disc 400 includes a third disc body 410, the third disc body 410 includes a main body 411 and a plurality of extensions 412 arranged at the outer periphery of the main body 411, and the negative electrode current collector disc 400 also includes flanges 420 corresponding in number to the extensions 412, the flanges 420 are integrally bent from the edge of the extensions 412, and are arranged to bulge along one side of the outer periphery of the third disc body 410. The negative electrode current collector disc 400 is provided with V-shaped grooves as first stress release grooves 430 at both ends of the folds of the extensions 412 and the flanges 420. The extension portion 412 is provided with a thinning portion 4121, which is formed by the two opposite surfaces of the extension portion 412 being recessed inwardly along the thickness direction of the extension portion 412. The thinning portion 4121 includes a first transition zone 4121a in which the thickness gradually decreases, a thickness maintaining zone 4121b in which the thickness remains unchanged, and a second transition zone 4121c in which the thickness gradually increases along the radial direction. The main body portion 411 is also provided with a second stress release groove 4111 formed by the recess in the edge of the main body portion 411. The second stress release groove 4111 is provided on both sides of the extension portion 412, and the edge of the second stress release groove 4111 is connected to the edge of the extension portion 412.

[0168] In addition, the negative electrode current collecting plate 400 also meets the following parameters:

[0169] The arc length L4a of the flange 420 along the circumferential direction of the third disk body 410 is 10 mm; the length L4b of the V-shaped groove inwardly concave along the circumferential direction of the third disk body 410 is 0.38 mm; the angle α of the V-shaped groove is 40°; the thickness L4c of the thickness maintaining area 4121b is 0.1 mm; the thickness L4d of the main body 411 is 0.2 mm; the length L4e of the thinning portion 4121 along the radial direction of the disk main body 411 is 0.23 mm; The radius L4f of the main body 411 is 19.7mm; the arc length L4g of the main body 411 at the second stress release groove 4111 is 8.4mm; the length L4h of the arc length of the main body 411 minus the arc length corresponding to the extension portion 412 and the arc length corresponding to the second stress release groove 4111 is 69.84mm; the length L4i of the second stress release groove 4111 that is recessed inward along the radial direction of the main body 411 is 0.68mm.

[0170] From the above, it can be seen that in the negative electrode current collecting plate 400, L4b / L4a=3.8%, L4c / L4d=50%, L4e / L4f=1.2%, L4g / L4h=12%, and L4i / L4f=3%.

[0171] Embodiment 2:

[0172] Example 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 400, which differs from Example 1 in that: L4b / L4a=6%, α is 35°, L4c / L4d=40%, L4e / L4f=1%, L4g / L4h=8%, L4i / L4f=2%.

[0173] Embodiment 3:

[0174] Example 3 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 400, which differs from Example 1 in that: L4b / L4a=8%, α is 45°, L4c / L4d=60%, L4e / L4f=4%, L4g / L4h=16%, and L4i / L4f=5%.

[0175] Comparative Example 1:

[0176] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between Comparative Example 1 and Example 1 is that L4b / L4a=2%.

[0177] Comparative Example 2:

[0178] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , and the difference between Comparative Example 2 and Example 1 is that L4b / L4a=12%.

[0179] Comparative Example 3:

[0180] 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 α is 25°.

[0181] Comparative Example 4:

[0182] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, which is different from Example 1 in that α is 65°.

[0183] Comparative Example 5:

[0184] 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 L4c / L4d=25%.

[0185] Comparative Example 6:

[0186] 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 L4c / L4d=65%.

[0187] Comparative Example 7:

[0188] 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 L4e / L4f=0.05%.

[0189] Comparative Example 8:

[0190] 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 L4e / L4f=8%.

[0191] Comparative Example 9:

[0192] Comparative Example 9 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, and the difference between the comparative example 9 and the embodiment 1 is that L4g / L4h=2%.

[0193] Comparative Example 10:

[0194] Comparative Example 10 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 L4g / L4h=25%.

[0195] Comparative Example 11:

[0196] 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 L4i / L4f=1%.

[0197] Comparative Example 12:

[0198] 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 L4i / L4f=8%.

[0199] Comparative Example 13:

[0200] Comparative Example 13 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, which is different from Example 1 in that the first stress release groove 430 is not provided.

[0201] Comparative Example 14:

[0202] Comparative Example 14 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , which differs from Example 1 in that a thinning portion 4121 is not provided.

[0203] Comparative Example 15:

[0204] Comparative Example 15 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400, which is different from Example 1 in that the second stress release groove 4111 is not provided.

[0205] Comparative Example 16:

[0206] Comparative Example 16 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 400 , which differs from Example 1 in that the first stress release groove 430 , the thinning portion 4121 and the second stress release groove 4111 are not provided.

[0207] Table 1 below tests the height difference (△H) of the arch of the main body 411, the maximum temperature (T1max) of the welding mark of the flange 420, the maximum temperature (T2max) of the welding mark of the main body 411, the number of times the main body 411 is folded before it breaks (C), and the time (t) required for the electrolyte to be injected into the battery for the negative electrode current collector 400 manufactured in the above embodiment and the comparative example. Among them:

[0208] The specific test method for the height difference △H (mm) of the arch of the main body 411 is as follows: the battery is sampled according to the normal process until the welding of the negative current collecting disc 400 and the shell wall is completed, and the groove rolling process is performed. Before the groove rolling process is performed, the height of the surface of the negative current collecting disc 400 is measured with a height gauge. The center position of the disk surface of the main body 411 of the negative current collecting disc 400 is taken as the center of the circle and the radius is 1mm. Three points are randomly selected for height measurement and the average value H is taken. The tool of the battery groove rolling equipment is continuously fed toward the center of the battery at a speed of 1800r / min to a rolling depth of 3.0mm. The battery is taken out and the height H is measured at three points in the middle position of the disk surface of the main body 411 of the negative current collecting disc 400 according to the same test method. The height difference △H of the arch is calculated as H = H - H. Under the condition of stress concentration, △H = 0.9~1.0mm.

[0209] The specific test method for the maximum temperature (T1max) of the weld mark of the flange 420 and the maximum temperature (T2max) of the weld mark of the main body 411 is as follows: the negative electrode current collector 400 is made into a battery. During the manufacturing process, a through hole with a diameter of 3 mm is drilled on the negative electrode cover plate of the battery, and the temperature control line is passed through the through hole and respectively attached to the weld mark between the flange 420 of the negative electrode current collector 400 and the shell wall and the weld mark between the disk surface of the main body 411 and the winding core 300. After the liquid is injected according to the normal battery manufacturing process, the cover is sealed and the capacity is divided to make a qualified battery. 10 cycles of charge and discharge are carried out 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. T1max represents the maximum temperature of the weld mark of the flange 420, and T2max represents the maximum temperature of the weld mark of the main body 411.

[0210] The specific test method for the number of folding times (C) when the main body 411 breaks after being folded is as follows: the flange 420 of the negative electrode current collecting disc 400 is completely cut off to leave a complete disc surface, and then the negative electrode current collecting disc 400 is folded along the central axis formed by the line connecting the midpoint of the flange 420 and the center of the circle, and one half of the surface is completely folded over and fitted to the other half, and then the folded negative electrode current collecting disc 400 is opened to 180°, which is counted as one folding, and then the same method is used for folding again. Each folding requires that the two half surfaces are completely fitted together, and then opened to 180° after folding, and repeated many times until a break occurs on the disc surface, and the number C is recorded.

[0211] Specific test method for the time (t) required for electrolyte injection into the battery: install the negative electrode collector plate 400 into the battery, and proceed to the liquid injection stage after the groove rolling process according to the normal battery manufacturing process. Inject 75g of electrolyte into the liquid holding cup, press the liquid holding cup into the groove opening of the groove, and make the sealing ring under the liquid holding cup completely close to the deep end surface of the groove. Then inject the liquid. 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 the positive pressure injection for 40 seconds, nitrogen is flushed into the battery, and the positive pressure inside the battery gradually becomes 0.8 MPa. 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. Then adjust to negative pressure injection and maintain it, and then adjust to positive pressure injection and maintain it. The positive and negative pressure injection cycles are repeated until the electrolyte in the liquid holding cup completely flows into the battery. The electrolyte height in the liquid holding cup is 0, and the time t when the electrolyte completely flows into the battery is recorded.

[0212] Table 2

[0213]

[0214]

[0215] As can be seen from Table 2, the range of L4b / L4a is set at 3% to 10%, the range of angle α is set at 30° to 50°, the range of L4c / L4d is set at 30% to 60%, the range of L4e / L4f is set at 1% to 5%, the range of L4g / L4h is set at 5% to 20%, and the range of L4i / L4f is set at 2% to 5%. The height difference △H of the arch of the main body 411 is usually 0.01mm to 0.02mm, the maximum temperature T1max of the weld mark of the flange 420 is usually 102 to 104°C, the maximum temperature T2max of the weld mark of the disk surface of the main body 411 is usually 112 to 115°C, the number of folding times C at which the disk surface of the main body 411 breaks after being folded in half is usually about 9 times, and the time t required for the electrolyte to be injected into the battery is usually 683 to 686. It can be seen that within the above numerical range, the structural strength, injection rate, and welding temperature rise of the negative electrode current collecting disc 400 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.

[0216] As can be seen from Table 2, if L4b / L4a is too small (the first stress release groove 430 is not recessed enough), the height of the plate surface arching of the main body 411 of the third plate body 410 will be too high; if L4b / L4a is too large, the maximum temperature of the weld mark of the flange 420 will increase. Therefore, setting L4b / L4a within a reasonable range can balance the height of the plate surface arching of the main body 411 of the third plate body 410 of the negative electrode current collector 400 and the maximum temperature of the weld mark of the flange 420.

[0217] As can be seen from Table 2, if the angle α is too small, the height of the plate surface of the main body 411 of the third plate body 410 will be too high; if the angle α is too large, the maximum temperature of the weld mark of the flange 420 will increase. Therefore, setting the angle α within a reasonable range can balance the height of the plate surface of the main body 411 of the third plate body 410 of the negative electrode current collector 400 and the maximum temperature of the weld mark of the flange 420.

[0218] As can be seen from Table 2, if L4c / L4d is too small (the thinned portion 4121 is too thin), the main body 411 of the third plate body 410 of the negative electrode current collecting plate 400 will be easily broken; if L4c / L4d is too large, the main body 411 of the third plate body 410 will be arched to a high height. Therefore, setting L4c / L4d within a reasonable range can balance the arched height of the main body 411 of the third plate body 410 of the negative electrode current collecting plate 400 and the structural strength of the third plate body 410.

[0219] As can be seen from Table 2, if L4e / L4f is too small (the thinned portion 4121 is too narrow), the main body 411 of the third plate 410 will be too high; if L4e / L4f is too large, the main body 411 of the third plate 410 of the negative electrode current collecting plate 400 will be easily broken. Therefore, setting L4e / L4f within a reasonable range can balance the height of the main body 411 of the third plate 410 of the negative electrode current collecting plate 400 and the structural strength of the third plate 410.

[0220] As can be seen from Table 2, if L4g / L4h is too small (the opening of the second stress release groove 4111 is too small), the height of the disk surface of the main body 411 of the third disk 410 will be higher and the electrolyte injection rate will decrease; if L4g / L4h is too large, the maximum temperature of the weld mark of the flange 420 will increase. Therefore, setting L4g / L4h within a reasonable range can balance the height of the disk surface of the main body 411 of the third disk 410 of the negative electrode current collector 400, the electrolyte injection rate and the maximum temperature of the weld mark of the flange 420.

[0221] As can be seen from Table 2, if L4i / L4f is too small (the second stress release groove 4111 is not recessed enough), the height of the disk surface of the main body 411 of the third disk 410 will be high and the electrolyte injection rate will be reduced; if L4i / L4f is too large, the maximum temperature of the disk surface weld mark of the main body 411 of the third disk 410 will be high. Therefore, setting L4i / L4f within a reasonable range can balance the height of the disk surface of the main body 411 of the third disk 410 of the negative electrode current collecting disk 400, the electrolyte injection rate and the maximum temperature of the disk surface weld mark of the main body 411 of the third disk 410.

[0222] It can be seen from Table 2 that if the first stress release groove 430 is not provided, the main body 411 of the third plate 410 will have a higher height of the plate surface arching. Therefore, providing the first stress release groove 430 is beneficial to controlling the height of the plate surface arching of the main body 411 of the third plate 410.

[0223] As can be seen from Table 2, if the thinning portion 4121 is not provided, the main body 411 of the third plate body 410 will have a higher height of the plate surface arching. Therefore, providing the thinning portion 4121 is beneficial to controlling the height of the plate surface arching of the main body 411 of the third plate body 410.

[0224] As can be seen from Table 2, if the second stress release groove 4111 is not provided, the main body 411 of the third disk body 410 will have a higher bulging height and a lower injection efficiency. Therefore, providing the first stress release groove 430 is beneficial to controlling the bulging height of the main body 411 of the third disk body 410 and improving the electrolyte injection efficiency.

[0225] It can be seen from Table 2 that if the first stress release groove 430 , the thinning portion 4121 and the second stress release groove 4111 are not provided, the main body 411 of the third plate 410 will be higher in height than when all three are provided.

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), and the connecting portion (221) is provided with a fuse groove (230) along the edge of the length direction thereof; The negative electrode current collector (400) comprises a third disc body (410) and a plurality of flanges (420) formed along the outer periphery of the third disc body (410) and protruding toward one side, the plurality of flanges (420) being in contact with the shell wall of the shell (100) and being welded together, the third disc body (410) comprising a main body (411) and a plurality of extensions (412) extending radially outward from the main body (411), the plurality of flanges (420) being connected to the plurality of extensions (412) in a one-to-one correspondence, and the negative electrode current collector (400) is also provided with a first A stress release groove (430), wherein the first stress release groove (430) is formed by the edges of the extension portion (412) and the edges of each flange (420) being recessed inwardly at the junction area, and the first stress release groove (430) is used for the flange (420) to bend along the first stress release groove (430) relative to the third disk body (410), and the extension portion (412) is provided with a thinning portion (4121) extending in a radial direction, and the thickness of the thinning portion (4121) is less than the thickness of other parts of the extension portion (412).

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 first stress release groove (430) is a V-shaped groove, and the V-shaped groove includes an angle α, and the range of α is 30° to 50°.

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 (220) on the same side is H2a, and the range of H2a is 0.6-1.4 mm; the thinning portion (4121) is formed by the two opposite surfaces of the extension portion (412) being recessed inwardly along the thickness direction, and the thinning portion (4121) includes, from the inside to the outside in the radial direction, a first transition zone (4121a) with a gradually decreasing thickness, a thickness maintaining zone (4121b) with a constant thickness, and a second transition zone (4121c) with a gradually increasing thickness, the thickness of the thickness maintaining zone (4121b) is L4c, the thickness of the main body (411) is L4d, and the range of L4c / L4d is 30%-60%.

4. The cylindrical lithium-ion battery according to claim 3, characterized in that: The edge of the second disk body (220) is provided with a plurality of first notches (250); the length of the thickness maintaining area (4121b) in the radial direction is L4e, the radius of the main body (411) is L4f, and the range of L4e / L4f is 1% to 5%.

5. The cylindrical lithium-ion battery according to claim 1, characterized in that: The connecting portion (221) has a first edge (231) extending along the length direction for forming the fuse slot (230), the length of the first edge (231) is L2a, and the range of L2a is 2 to 4 mm; the arc length of the flange (420) along the circumferential direction is L4a, and the length of the first stress release slot (430) recessed inward along the circumferential direction is L4b, and the range of L4b / L4a is 3% to 10%.

6. The cylindrical lithium-ion battery according to any one of claims 1 to 5, 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 negative electrode current collecting disc (400) is also provided with a second stress release groove (4111) at the edge, the second stress release groove (4111) is formed by the edge of the main body (411) being recessed inwardly, and the edge of the second stress release groove (4111) is connected to the edge of the extension part (412).

7. The cylindrical lithium-ion battery according to claim 6, 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 total arc length of the main body (411) at the second stress release groove (4111) is L4g, and the total arc length of the main body (411) minus the total arc length corresponding to the extension portion (412) is L4h, and the range of L4g / L4h is 5% to 20%.

8. The cylindrical lithium-ion battery according to claim 6, characterized in that: The second disk body (220) is provided with a plurality of first notches (250), each of the first notches (250) is arranged at 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 length of the second stress release groove (4111) recessed inward in the radial direction is L4i, the radius of the main body (411) is L4f, and the range of L4i / L4f is 2% to 5%.

9. The cylindrical lithium-ion battery according to claim 8, 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 bottom of the first stress release groove (430) is located at the junction of the flange (420) and the extension part (412).

10. The cylindrical lithium-ion battery according to claim 7, 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 second connecting portion (2212) has a width W2c in the radial direction in the area corresponding to the slit (240), and the range of W2c is 1-3 mm.

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