Cathode collector plate and cylindrical lithium ion battery

Abstract

The invention provides a cathode collector plate and a cylindrical lithium ion battery, the cathode collector plate comprises a plate body and a plurality of turnups protruding along one side of the outer periphery of the plate body, the turnups are used for being connected with the shell wall of a shell of the cylindrical lithium ion battery in an attached mode, the edge of the cathode collector plate is further provided with a first stress release groove, and the first stress release groove is used for releasing stress of the cylindrical lithium ion battery. The edge of the disc body and the edge of each turned-over edge are jointly sunken inwards in a junction area to form the first stress release groove, and the first stress release groove is used for enabling the turned-over edges to be bent relative to the disc body along the first stress release groove. And the problems of deformation, arching, welding spot breakage and the like of the negative collector plate caused by the channeling process are solved.

Description

Technical Field

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

[0002] Currently, in the 46 series cylindrical lithium-ion batteries, please refer to Fig.11 and Fig.12 ,exist Fig.11 The figure shows the state where the negative electrode current collector disc 810 is assembled into the battery shell 820 but without groove rolling. The negative electrode side of the cylindrical lithium-ion battery is on the top and the positive electrode side is on the bottom, wherein the negative electrode current collector disc 810 generally includes a disc body 811 and a raised flange 812 located at the periphery of the disc body. When assembling the cylindrical lithium-ion battery, the disc body 811 is welded to the negative end of the winding core 830, and the outer surface of the flange 812 is attached to the inner surface of the shell 820 and connected by penetration welding, so that the shell 820 and the negative electrode of the winding core 830 are conductively connected. After the flange 812 is welded to the shell 820, the place where the shell 820 and the flange 812 of the negative electrode current collector disc 810 are welded is grooved, and finally a cap is added to perform a sealing process from one seal to the final seal. As shown in FIG. Fig.12 As shown, Fig.12 yes Fig.11 After the grooves are rolled, the shell 820 is grooved toward the center of the shell, pulling the flange 812 of the negative electrode current collector 810 to bend together, thereby causing the disk body 811 connected to the flange 812 to also deform in a wavy shape, resulting in the welding point between the disk body 811 of the negative electrode current collector and the negative end of the winding core 830 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.

[0003] In addition, when rolling grooves, the welded flange 812 is rolled grooves together, resulting in the middle of the plate surface of the negative electrode collector plate 810 bulging to form an arch bridge shape, such as Fig.12 As shown, this will tear the weld between the disk surface and the negative end of the winding core 830, 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

[0004] The embodiments of the present application provide a negative electrode current collector and a cylindrical lithium-ion battery to at least solve the technical problems of the existing cylindrical lithium-ion battery such as deformation of the negative electrode current collector during the groove rolling process and tearing and breaking of the welding points between the disc and the winding core.

[0005] A first aspect of the present application provides a negative electrode current collector disk for a cylindrical lithium-ion battery, comprising a disk body and a plurality of flanges bent toward one side along the outer peripheral edge of the disk body, wherein the plurality of flanges are used to fit and connect with the shell wall of the shell of the cylindrical lithium-ion battery, and the negative electrode current collector disk is further provided with a first stress release groove at the edge, wherein the first stress release groove is formed by the edge of the disk body and the edges of each flange being jointly recessed inward at the junction, and the first stress release groove is used for the flange to bend relative to the disk body along the first stress release groove.

[0006] The negative electrode current collector according to the embodiment of the present application has at least the following beneficial effects:

[0007] The first stress release groove is formed by recessing the edge of the disk body and the edge of each flange inward. During the grooving process, when the flange is bent relative to the disk body, the bending occurs near the junction area between the disk body and the flange due to the action of the first stress release groove. In addition, the first stress release groove provides space for material deformation at the bending position, thereby reducing material extrusion or deformation transmitted to the disk body or the flange, thereby avoiding problems such as fracture of welding points caused by pulling and setting, and bulging in the middle of the disk surface due to deformation of the disk body and the flange.

[0008] In a possible implementation, the arc length of the flange along the circumferential direction of the disk body is L1, the inward concave length of the first stress release groove along the circumferential direction of the disk body is L2, and the range of L2 / L1 is 3% to 10%.

[0009] By reasonably setting the range of L2 / L1, it is possible to take into account both the structural strength of the negative electrode collector and the degree of flange bending deformation.

[0010] In a possible implementation manner, the bottom of the first stress release groove is located at the junction of the flange and the disc body.

[0011] By arranging the bottom of the first stress release groove at the junction of the flange and the disk body, the position where the flange is bent relative to the disk body can be located exactly at the junction of the two, thereby minimizing the adverse effects of the bending position on the disk body and the flange.

[0012] In a possible implementation manner, the first stress release groove is a V-shaped groove, the V-shaped groove includes a third side and a fourth side, the third side and the fourth side form an angle α, and the range of α is 30° to 50°.

[0013] By properly setting the angle α, both the guiding function of the positioning groove and the welding area can be taken into consideration.

[0014] In a possible embodiment, the disk body includes a main body and a plurality of connecting parts extending radially outward from the main body, the plurality of flanges are connected to the plurality of connecting parts in a one-to-one correspondence, the connecting parts include a fifth side and a sixth side connected to the edge of the main body, the connecting parts are provided with a thinning part extending from the fifth side to the sixth side, and the thickness of the thinning part is less than the thickness of other parts of the connecting part.

[0015] By providing the connecting portion and the thinning portion, the thinning portion has the function of bearing stress. On the basis of the first stress release groove, the thinning portion can play the role of dispersing stress again to avoid deformation of the disc body.

[0016] In a possible embodiment, the thinning portion is formed by two opposite surfaces of the connecting portion being recessed inwardly along the thickness direction of the connecting portion, and the thinning portion includes, from the inside to the outside along the radial outward direction of the main body, a first transition zone with gradually decreasing thickness, a thickness maintaining zone with unchanged thickness, and a second transition zone with gradually increasing thickness, the thickness of the thickness maintaining zone is L3, the thickness of the main body is L4, and the range of L3 / L4 is 30% to 60%.

[0017] By properly setting the range of L3 / L4, both the structural strength and the stress dispersion effect of the connection can be taken into account.

[0018] In a possible implementation manner, the length of the thickness maintaining zone of the thinned portion along the radial direction of the disk main body is L5, the radius of the main body is L6, and the range of L5 / L6 is 1% to 5%.

[0019] By properly setting the range of L5 / L6, both the structural strength and the stress dispersion effect of the connection can be taken into account.

[0020] In a possible implementation, 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 an inward depression of the edge of the main body, and the edge of the second stress release groove is connected to the edge of the connecting portion.

[0021] By providing a second stress relief groove, the second stress relief groove serves as a further supplement to further resolve the stress caused by the flanging and bending during the grooving process, so that the stress on the main body is greatly reduced, thereby avoiding deformation of the main body structure.

[0022] In a possible implementation, the total arc length of the main body at the second stress release groove is L7, the total arc length of the main body minus the total arc length at the connecting portion is L8, and the range of L7 / L8 is 5% to 20%.

[0023] By reasonably setting the range of L7 / L8, both the structural strength and the stress dispersion effect of the negative electrode collector can be taken into account.

[0024] In a possible implementation manner, the inwardly recessed length of the second stress release groove along the radial direction of the main body is L9, the radius of the main body is L6, and the range of L9 / L6 is 2% to 5%.

[0025] By reasonably setting the range of L9 / L6, both the electrolyte injection efficiency and the stress dispersion effect can be taken into account.

[0026] A second aspect of the present application provides a cylindrical lithium-ion battery, comprising a shell, a winding core and a negative electrode collector disk in any of the above-mentioned embodiments, wherein the shell is provided with an inwardly recessed rolling groove portion extending along the circumference of the shell, the disk body of the negative electrode collector disk is connected to the negative end of the winding core, and the flange of the negative electrode collector disk is fitted and connected to the shell wall of the rolling groove portion of the shell.

[0027] The cylindrical lithium-ion battery according to the embodiment of the present application has at least the following beneficial effects:

[0028] By providing the first stress release groove at the flange, the negative electrode current collector plate undergoing the groove rolling process does not deform and the plate surface does not bulge. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 is a cross-sectional schematic diagram of a cylindrical lithium-ion battery after groove rolling provided in an embodiment of the present application;

[0031] Figure 2 is a cross-sectional schematic diagram of a cylindrical lithium-ion battery without groove rolling provided in an embodiment of the present application;

[0032] Figure 3 It is a schematic diagram of the structure of a negative electrode current collector provided in an embodiment of the present application;

[0033] Figure 4 yes Figure 3 The local schematic diagram of the A in the middle;

[0034] Figure 5 yes Figure 4 The local schematic diagram at E in the middle; Figure 6It 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;

[0035] Figure 7 yes Figure 6 The local schematic diagram of point B in the middle;

[0036] Figure 8 yes Figure 6 The local schematic diagram of the C in the middle;

[0037] Fig. 9 is a cross-sectional view of a negative electrode current collector provided in an embodiment of the present application;

[0038] Fig.10 yes Fig. 9 The local schematic diagram of point D in the middle;

[0039] Fig.11 It is a cross-sectional schematic diagram of a cylindrical lithium-ion battery without groove rolling in the related art;

[0040] Fig.12 It is a cross-sectional schematic diagram of a cylindrical lithium-ion battery after groove rolling in the related art.

[0041] Reference numerals:

[0042] 100-negative electrode current collecting disk, 110-disk body, 111-main body, 1111-second stress release groove, 1112-center hole, 1113-auxiliary hole, 112-connecting portion, 1121-thinning portion, 1121a-first transition zone, 1121b-thickness maintaining zone, 1121c-second transition zone, 1122-fifth side, 1123-sixth side, 120-flanging, 121-first side, 122-second side, 130-first stress release groove, 131-third side, 1311-first straight side, 1312-first chamfered portion, 132-fourth side, 1321-second straight side, 1322-second chamfered portion;

[0043] 200-housing, 210-groove portion;

[0044] 300-coil core;

[0045] 810 - negative electrode current collecting disk, 811 - disk body, 812 - flange, 820 - shell, 830 - winding core. DETAILED DESCRIPTION

[0046] Embodiments of the present embodiment are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present embodiment, and should not be construed as limiting the present embodiment.

[0047] In the description of this embodiment, it should be understood that descriptions involving orientation, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on this embodiment.

[0048] In the description of this embodiment, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed", etc. are understood to exclude the number itself, and "above", "below", "within", etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0049] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this embodiment based on the specific content of the technical solution.

[0050] Figure 1 is a schematic diagram of a cylindrical lithium-ion battery provided in an embodiment of the present application, Figure 1 In the figure, the negative electrode side of the cylindrical lithium-ion battery is on the top and the positive electrode side is on the bottom. Figure 1 The cylindrical lithium-ion battery in the Figure 2 It is a cylindrical lithium-ion battery that has not yet been grooved. Figure 1 As shown, the cylindrical lithium-ion battery includes a negative electrode current collector disk 100, a winding core 300, a shell 200, etc. Among them, the negative terminal of the winding core 300 is connected to the shell 200 through the negative electrode current collector disk 100, and the shell 200 serves as the negative electrode of the cylindrical lithium-ion battery and is used to be electrically connected to an external electrical device. The shell 200 is provided with an inwardly recessed rolling groove portion 210 extending in the circumferential direction, the disk body 110 of the negative electrode current collector disk 100 is connected to the negative terminal of the winding core 300, and the flange 120 of the negative electrode current collector disk 100 is connected to the shell wall of the rolling groove portion 210 in the shell 200.

[0051] Figure 3It is a structural schematic diagram of the negative electrode collector disc 100 provided in an embodiment of the present application, and the negative electrode collector disc 100 includes a disc body 110 and a plurality of flanges 120 formed by a protrusion along one side of the outer periphery of the disc body 110. It can be understood that the flange 120 is used to fit and connect with the shell wall of the shell 200 of the cylindrical lithium battery. The shell wall of the cylindrical lithium battery refers to the inner wall of the shell 200 of the cylindrical lithium battery, so that the winding core 300 forms a passage between the negative electrode collector disc 100 and the shell 200, so that the shell 200 itself serves as the negative electrode of the cylindrical lithium-ion battery.

[0052] Specifically, the disc body 110 is the main structural part of the negative electrode current collector disc 100, which is in the shape of a thin sheet as a whole. The disc body 110 includes two disc surfaces facing away from each other, one of which is used to connect to the negative end of the winding core 300, specifically by welding, and the other disc surface is open before being sealed. In the subsequent injection process, the electrolyte will enter the winding core 300 through the disc surface on this side. There are multiple flanges 120, that is, the flanges 120 are not a complete circular ring structure. Multiple flanges 120 protrude toward the negative electrode side along the outer periphery of the disc body 110 in a direction away from the disc surface, for example, protrude at an angle approximately perpendicular to the disc surface, and are arranged at intervals from each other. Multiple flanges 120 increase the welding area between the negative electrode current collector disc 100 and the shell 200 to improve the connection strength between the negative electrode current collector disc 100 and the shell 200. 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.

[0053] It is understood that the connection between the plate body 110 and the flange 120 can be any fixed connection method. To ensure a stable connection, structural strength and processing economy, the plate body 110 and the flange 120 can be connected as one piece, for example, integrally formed by stamping. It is further understood that the integral formation of the plate body 110 and the flange 120 by stamping will form a crease at the connection between the plate body 110 and the flange 120.

[0054] In this embodiment, the negative electrode current collector disc 100 is further provided with a first stress release groove 130 at the edge, and the first stress release groove 130 is formed by the edge of the disc body 110 and the edge of each flange 120 being concave inward at the junction area, and the first stress release groove 130 is used for the flange 120 to bend relative to the disc body 110 along the first stress release groove 130. It can be understood that the negative electrode current collector disc 100 has an edge formed on the disc body 110 and an edge formed on the flange 120, and these edges together constitute the edge of the negative electrode current collector disc 100, thereby, the first stress release groove 130 is formed on both sides of the connection between each flange 120 and the disc body 110, such as the two sides of the aforementioned fold, and therefore, for each flange 120, two symmetrically arranged first stress release grooves 130 are formed at its bottom.

[0055] It can be understood that the first stress release groove 130 is a structure formed by the edge of the negative electrode current collecting disk 100 being concave from the outside to the inside. This structure will cause the material length of the flange 120 and the disk body 100 corresponding to the first stress release groove 130 to become shorter. When the flange 120 is bent relative to the disk body 110, the first stress release groove 130 can release stress, so that the material in the area between the two first stress release grooves 130 is bent preferentially, that is, the bending occurs at the junction area of ​​the flange 120 and the disk body 110, such as the crease, thereby avoiding a series of problems caused by the deformation of the disk body 110 and the flange 120 themselves. Therefore, the first stress release groove 130 is formed by recessing the edge of the disk body 110 and the edge of each flange 120 inward. During the grooving process, when the flange 120 is bent relative to the disk body 110, the bending occurs near the junction area between the disk body 110 and the flange 120 due to the action of the first stress release groove 130. In addition, the first stress release groove 130 provides space for material deformation at the bending position, reduces material extrusion or deformation transmission to the disk body 110 or the flange 120, 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 disk body 110 and the flange 120.

[0056] As mentioned above, the first stress release groove 130 is formed by the edges of the disc body 110 and the edges of each flange 120 being concave inward at the junction. Therefore, it can be understood that part of the first stress release groove 130 is set at the flange 120 and part is set on the disc body 110. Specifically, refer to Figure 4 , Figure 4 yes Figure 3 The local schematic diagram at point A in the middle, specifically, the flange 120 includes a first edge 121 and a second edge 122 connected to the edge of the disk body 110, and the edge of the disk body 110 includes a fifth edge 1122 and a sixth edge 1123 located at the connecting portion 112, wherein the fifth edge 1122 is connected to the first edge 121, and the sixth edge 1123 is connected to the second edge 122, thereby, a portion of the first stress release groove 130 is formed by the first edge 121 and the second edge 122 being recessed inwardly toward one end of the disk body 110, and the other portion is formed by the fifth edge 1122 and the sixth edge 1123 being recessed inwardly at the end connected to the flange 120.

[0057] In order to make the position where the flange 120 is bent relative to the disc body 110 exactly at the junction of the two, in some embodiments, the bottom of the first stress release groove 130 is located at the junction of the flange 120 and the disc body 110. For example, in the negative electrode current collector 100 formed by stamping, the flange 120 is formed by bending at the edge of the disc body 110, and there is a fold between the two, which is the junction of the flange 120 and the disc body 110. Here, the position where the bottom of the first stress release groove 130 is located refers to the position where the first stress release groove 130 is most deeply concave. It can be understood that the bottom of the first stress release groove 130 is at the junction of the flange 120 and the disc body 110, so that the position where the flange 120 is bent relative to the disc body 110 is exactly at the junction of the two, so that when the flange 120 is bent relative to the disc body 110, the adverse effect of the bending position on the disc body 110 and the flange 120 is minimized.

[0058] Of course, this is not limited to this. It can be understood that the bottom of the first stress release groove 130 can be set on any side of the disc body 110 or the flange 120, so that the flange 120 is bent along the line between the bottoms of the two first stress release grooves 130 to more accurately locate the position and direction of the bending, so that the bending occurs at the required position as much as possible, and the direction of the bending can be controlled.

[0059] For further information, please refer to Figure 6 and Figure 7 , Figure 6 It is a view of the negative electrode current collector 100 from the side without flange to the side with flange 120. Figure 7 yes Figure 6 In the partial schematic diagram at B, the arc length of the flange 120 along the circumferential direction of the disk body 110 is L1, and the length of the first stress release groove 130 that is recessed inward along the circumferential direction of the disk body 110 is L2, and the range of L2 / L1 is 3% to 10%. For example, the range of L2 / L1 can be 3%, 3.8%, 6%, 8% and 10%, etc. In some embodiments, the length of L2 is 0.38mm and the length of L1 is 10mm. If the range of L2 / L1 is greater than 10%, L2 / L1 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 120 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 120 here is weak, which increases the difficulty of control during production and transportation and during feeding during the process. The flange 120 is easier to deform and bend, making it difficult to determine whether the tooling is welded to the shell wall, and the problem of cold welding is prone to occur. If the range of L2 / L1 is less than 3%, L2 / L1 is too small, the depth of the V-groove is too shallow, and the guiding effect of the V-groove is greatly reduced.

[0060] For further information, please refer to Figure 4 and Figure 5 The first stress release groove 130 is a V-shaped groove, and the V-shaped groove includes a third side 131 and a fourth side 132 forming the V-shaped groove, and the third side 131 and the fourth side 132 form an angle α, and the range of α is 30° to 50°. Specifically, the third side 131 includes a first straight side portion 1311 and a first chamfered portion 1312, and the fourth side 132 includes a second straight side portion 1321 and a second chamfered portion 1322, and the first chamfered portion 1312 is connected to the second chamfered portion 1322, wherein the first straight side portion 1311 and the second straight side portion 1321 form the angle α. It can be understood that the third side 131 includes a first straight side portion 1311 and a first chamfered portion 1312 which are straight segments from outside to inside, and the fourth side 132 includes a second straight side portion 1321 and a second chamfered portion 1322 which are straight segments from outside to inside, and the first chamfered portion 1312 is connected to the second chamfered portion 1322, 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 120 is welded to the shell 200, when rolling the groove together with the shell 200, 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 middle of the disk surface of the disk body 110 of the negative electrode collector 100 being arched when rolling the 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 100 and the shell 200 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 100 forms the flange 120 and before the rolling groove process. It can be understood that by providing the first chamfered portion 1312 and the second chamfered portion 1322 , stress concentration in the bottom area of ​​the V-shaped groove can be reduced.

[0061] In some embodiments, the shape of the first stress release groove 130 is not limited to a V-shaped groove, and may be, for example, a rectangular groove, a U-shaped groove, etc.

[0062] Furthermore, the first stress release groove 130 is arranged at the junction of the flange 120 and the disc body 110. The first stress release groove 130 is a V-shaped groove. The V-shaped groove includes a third side 131 and a fourth side 132 forming the V-shaped groove. The third side 131 is located at the flange 120, and the fourth side 132 is located at the disc body 110. It can be understood that the grooving process will cause the flange 120 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 grooving 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 130 is set at the junction of the flange 120 and the disc body 110, and the bending occurs on the same plane as the disc body 110, 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 120 protrudes from the edge of the disk body 110 away from the disk surface, there is a crease between the disk body 110 and the flange 120. At this time, the bottom of the first stress release groove 130 is located at the crease, that is, the bottom is located both at the connecting portion 112 and at the flange 120.

[0063] For further information, please refer to Fig. 9 and Fig.10 , Fig.10 yes Fig. 9In the local schematic diagram at point D in the middle, the disk body 110 includes a main body 111 and a connecting portion 112 extending radially outward from the main body 111, the number of the connecting portions 112 corresponds to the number of the flanges 120, that is, the flanges 120 are connected to the connecting portions 112 in a one-to-one correspondence, the connecting portion 112 is provided with a thinning portion 1121, the thickness of the thinning portion 1121 is less than the thickness of other parts of the connecting portion 112, the connecting portion 112 includes a fifth side 1122 and a sixth side 1123 connected to the edge of the main body 111, the thinning portion 1121 extends from the fifth side 1122 to the sixth side 1123, and the aforementioned fourth side 132 is provided on the connecting portion 112. By setting the thinning portion 1121, it can be effectively avoided that the flange 120 of the negative electrode collector disk 100 is subjected to groove rolling after being welded to the shell 200. When the groove rolling depth is too deep, the pulling force of the flange 120 increases, and the flange 120 and even the edge of the disk surface are pulled and deformed in the axial direction. When the V-shaped groove set at the junction of the flange 120 and the disk surface has been deformed, and the deformation force is not enough, the thinning portion 1121 plays a secondary effect of relieving stress concentration, and the thinning portion 1121 continues to deform until the required deformation amount is reached. Since the stress is decomposed by the first stress release groove 130 and the thinning portion 1121 respectively, the stress is not concentrated in the center of the disk surface, so that it will not affect the welding of the disk surface and the negative side pole ear of the winding core 300, and the middle part of the disk surface will not be deformed and arched. The reliability of the welding of the negative electrode collector disk 100 is guaranteed, and the safety performance of the battery cell is improved. At the same time, by providing the connecting portion 112 extending radially outward from the main body 111 , after the negative electrode current collecting disc 100 is inserted into the shell 200 , a gap is left between the shell wall of the shell 200 and the main body 111 , thereby accelerating the injection of electrolyte.

[0064] Furthermore, the thinning portion 1121 extends from the fifth side 1122 along the circumferential direction of the main body 111 to the sixth side 1123 . The extension in the circumferential direction is to ensure that the force transmitted by the bending of the flange 120 during the grooving process can be evenly absorbed by the thinning portion 1121 .

[0065] Furthermore, the thinning portion 1121 is formed by two opposite surfaces of the connecting portion 112 being recessed inwardly along the thickness direction of the connecting portion 112. The thinning portion 1121 includes a first transition zone 1121a with a gradually decreasing thickness, a thickness-maintaining zone 1121b with a constant thickness, and a second transition zone 1121c with a gradually increasing thickness along the radial outward direction of the main body 111. Fig.10As shown, the thickness of the thickness-maintaining area 1121b is L3, the thickness of the main body 111 is L4, and the range of L3 / L4 is 30% to 60%. For example, the range of L3 / L4 can be 30%, 35%, 40%, 45%, 50%, 55% and 60%, without specific limitation. In some embodiments, the thickness L3 of the thickness-maintaining area 1121b is 0.1 mm, the thickness L4 of the main body 111 is 0.2 mm, and the ratio of L3 / L4 is 50%. When L3 / L4 is less than 30%, the thickness of the thinned portion 1121 is too thick. During the groove rolling process of the negative electrode current collecting disk 100, when the groove depth pulls the flange 120, the thinned portion 1121 cannot play a good role in relieving stress, and most of the stress is concentrated at the junction of the flange 120 and the connecting portion 112 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 being prone to risks such as thermal runaway. When L3 / L4>60%, the thickness of the thinned portion 1121 is too thin, and the negative electrode current collector 100 pulls the flange 120 during the groove rolling process, causing the thinned portion 1121 to be severely deformed, insufficient in strength, and unable to be processed. The thinned portion 1121 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 1121a and the second transition zone 1121c are set to achieve smooth thinning of the thinned portion 1121, reduce stress concentration between the connecting portion 112 and the thickness maintaining zone 1121b, and increase the overall structural strength of the thinned portion 1121 through smooth thinning, thereby preventing the thinned portion 1121 from breaking during transportation and processing of the negative electrode current collector 100.

[0066] Furthermore, the thickness variation slopes of the first transition zone 1121 a and the second transition zone 1121 c are the same, which facilitates the manufacture of the thinned portion 1121 .

[0067] In some embodiments, the first transition zone 1121a and the second transition zone 1121c may not be provided, or only one of the first transition zone 1121a and the second transition zone 1121c may be provided, thereby saving the manufacturing process of the thinning portion 1121.

[0068] In some embodiments, the length of the thickness maintaining area 1121b of the thinning portion 1121 along the radial direction of the disk main body 111 is L5, the radius of the main body 111 is L6, and the range of L5 / L6 is 1% to 5%. For example, the ratio of L5 / L6 can be 1%, 1.2%, 2%, 3%, 4% and 5%, etc., and is not specifically limited. For example, the length of L5 is 0.23mm, and the radius of the main body 111 is 19.7mm, then L5 / L6 is 1.2%. When L5 / L6 is less than 1%, the width of the thinning portion 1121 is too narrow. When rolling the groove, the groove depth is deep, and the thinning portion 1121, which plays a secondary protective role, begins to deform and bend. However, the bending must have a certain bending radius to achieve the bending function. At this time, the width of the thinning portion 1121 is too narrow, and the bending deformation cannot be completed directly in the thinning portion 1121 during the secondary bending. The disk surface of normal thickness around the thinning portion 1121 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 L5 / L6 is greater than 5%, the width of the thinning portion 1121 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.

[0069] Furthermore, if Figure 6 , Figure 7 and Figure 8 As shown, the negative electrode current collector 100 is further provided with a second stress release groove 1111 at the edge, and the second stress release groove 1111 is formed by the inner depression of the edge of the main body 111 located on both sides of the connecting portion 112, and the edge of the second stress release groove 1111 is connected to the edge of the connecting portion 112. By providing the second stress release groove 1111, the stress is transferred from the flange 120 to the thinning portion 1121 through the connecting portion 112, and then to the second stress release groove 1111. At this time, the second stress release groove 1111 serves as a third stress relief structure, and the second stress release groove 1111 further relieves the stress caused by the bending of the flange 120 during the groove rolling process, so that the stress on the main body 111 is greatly reduced, and the structural deformation of the main body 111 is avoided.

[0070] It is understandable that for the location of a single connection portion 112, there is a pair of second stress release grooves 1111, and the two second stress release grooves 1111 are respectively arranged in the area connected to the connection portion 112 on the main body 111, which is conducive to dispersing stress and further ensuring that the structure of the main body 111 is not deformed. Furthermore, the shape of the second stress release groove 1111 is arc-shaped, which is conducive to avoiding stress concentration.

[0071] Furthermore, if Figure 8 As shown, Figure 8 yes Figure 6 In the partial schematic diagram at C in the middle, the main body 111 is provided with a plurality of second stress release grooves 1111 and a plurality of connecting parts 112. The total arc length of the main body 111 at the second stress release grooves 1111 is L7, and the total arc length of the main body 111 minus the total arc length corresponding to the connecting parts 112 is L8. The range of L7 / L8 is 5% to 20%, for example, the ratio of L7 / L8 can be 5%, 7%, 10%, 12%, 15%, 17% and 20%. The arc length L7 corresponding to the main body 111 at the second stress release grooves 1111 is the total arc length of all the second stress release grooves 1111, and L8 is the total arc length of the main body 111 minus the arc length corresponding to the plurality of connecting parts 112. Figure 6 and Figure 8 Only a section of the arc length L7 of the second stress relief groove 1111 and only a section L8 are marked. When L7 / L8 is less than 5%, the arc length is too small, and the second stress release groove 1111 structure for relieving stress concentration cannot effectively decompose stress, resulting in some stress still being concentrated on the disk surface of the main body 111, resulting in a certain height of arching and deformation in the middle of the disk surface after rolling. When the electrolyte flows into the battery cell through the through hole of the disk surface, the arc of the second stress release groove 1111 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 L7 / L8>20%, the arc length is too long, the structural strength of the second stress release groove 1111 will be reduced, and the second stress release groove 1111 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 120 is welded to the shell 200, the problem of cold welding is easy to occur. In some embodiments, L7 is 8.4 mm, L8 is 69.84 mm, and the ratio of L7 / L8 is 12%.

[0072] Furthermore, the inward recessed length of the second stress release groove 1111 along the radial direction of the main body 111 is L9, the radius of the main body 111 is L6, and the range of L9 / L6 is 2% to 5%, for example, the ratio of L9 / L6 can be 2%, 3%, 4% and 5%. When L9 / L6 is less than 2%, the depth of the second stress release groove 1111 is too shallow. As the third stress concentration relief protection structure, the second stress release groove 1111 cannot effectively decompose stress, resulting in some stress still being concentrated on the disk surface. After rolling, 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 1111 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 L9 / L6 is greater than 5%, the depth of the second stress release groove 1111 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, L9 is 0.68mm and L6 is 19.7mm, then the ratio of L9 / L6 is 3%.

[0073] Furthermore, the main body 111 is also provided with a central hole 1112 located at its center and a plurality of auxiliary holes 1113 located on the periphery of the central hole 1112. The central hole 1112 and the plurality of auxiliary holes 1113 are used to inject electrolyte into the battery. It is understandable that the winding core 300 is made by a winding process, and a circular winding core 300 hole is formed at the center of the winding core 300 after winding. In order to match the shape of the winding core 300 hole, the shape of the central hole 1112 is preferably circular. In this case, the central hole 1112 is co-centered with the main body 111. It is understandable that the diameter of the central hole 1112 can be specifically selected based on achieving a balance between the injection efficiency and the weldable area. The size of the auxiliary hole 1113 can be specifically selected based on achieving a balance between the injection efficiency and the weldable area. Furthermore, the auxiliary holes 1113 are waist-shaped holes, and there are four of them. The combined pattern of the four auxiliary holes 1113 is a centrally symmetrical pattern, and the center of symmetry is the center of the center hole 1112, so as to ensure uniformity during electrolyte injection.

[0074] The effects of the present application are further described below with specific examples and comparative examples.

[0075] It should be noted that the following embodiments and comparative examples of the present application are all designed and manufactured based on common cylindrical lithium-ion batteries in the art. Therefore, except for manufacturing the negative electrode current collector 100 according to the aforementioned structure, other components and materials can be obtained by referring to cylindrical lithium-ion batteries. For example, the positive electrode sheet, the negative electrode sheet and the electrolyte can be obtained by referring to the following preparation method:

[0076] Preparation of positive electrode sheet: Take lithium nickel cobalt manganese oxide, carbon nanotube conductive agent, conductive carbon black, polyvinylidene fluoride PVDF binder as solid substances of positive electrode slurry, disperse the solid substances in N-methyl-pyrrolidone, mix them evenly in a homogenizer, apply the slurry on both sides of aluminum foil, dry it, and obtain the positive electrode sheet.

[0077] Preparation of negative electrode sheet: Take negative electrode active material, acetylene black conductive agent, thickener (hydroxymethyl cellulose), and polyacrylate binder as solid substances of negative electrode slurry, disperse the solid substances in deionized water, mix them evenly in a homogenizer, apply the slurry on both sides of copper foil, and dry to obtain negative electrode sheet.

[0078] Preparation of electrolyte: Ethylene carbonate, ethyl methyl carbonate and diethyl carbonate are mixed to obtain an organic solvent, and then fully dried lithium salt LiPF is dissolved in the mixed organic solvent to prepare an electrolyte.

[0079] The components and materials obtained in the above manner can be assembled according to the known technology in the art to obtain an experimental 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 positive electrode tabs and negative electrode tabs are cut and stacked at both ends of the winding core 300, and then the negative electrode collector plate 100 and the positive electrode collector plate are welded to the winding core 300, and then the negative electrode collector plate 100 is welded to the shell 200, and the negative electrode cover plate is welded to the shell 200, and the injection, sealing, and formation processes are completed to obtain an experimental cylindrical lithium-ion battery.

[0080] Embodiment 1:

[0081] Embodiment 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collector disc 100, the negative electrode current collector disc 100 includes a disc body 110, the disc body 110 includes a main body 111 and a plurality of connecting parts 112 arranged at the outer periphery of the main body 111, and the negative electrode current collector disc 100 also includes flanges 120 corresponding in number to the connecting parts 112, the flanges 120 are integrally bent from the edge of the connecting part 112, and are arranged to bulge along one side of the outer periphery of the disc body 110. The negative electrode current collector disc 100 is provided with V-shaped grooves as first stress release grooves 130 at both ends of the folds of the connecting part 112 and the flanges 120. The connecting portion 112 is provided with a thinning portion 1121, which is formed by two opposite surfaces of the connecting portion 112 being recessed inwardly along the thickness direction of the connecting portion 112. The thinning portion 1121 includes a first transition zone 1121a in which the thickness gradually decreases, a thickness maintaining zone 1121b in which the thickness remains unchanged, and a second transition zone 1121c in which the thickness gradually increases along the radial direction. The main body 111 is also provided with a second stress release groove 1111 formed by a recess in the edge of the main body 111. The second stress release groove 1111 is provided on both sides of the connecting portion 112, and the edge of the second stress release groove 1111 is connected to the edge of the connecting portion 112.

[0082] In addition, the negative electrode current collector 100 also meets the following parameters:

[0083] The arc length L1 of the flange 120 along the circumferential direction of the disk body 110 is 10 mm; the length L2 of the V-shaped groove inwardly recessed along the circumferential direction of the disk body 110 is 0.38 mm; the angle α of the V-shaped groove is 40°; the thickness L3 of the thickness maintaining area 1121b is 0.1 mm; the thickness L4 of the main body 111 is 0.2 mm; the length L5 of the thinning portion 1121 along the radial direction of the disk main body 111 is 0.23 mm; the radius L6 of the main body 111 is 19.7 mm; the arc length L7 corresponding to the main body 111 at the second stress release groove 1111 is 8.4 mm; the length L8 of the arc length of the main body 111 minus the arc length corresponding to the connecting portion 112 and the arc length corresponding to the second stress release groove 1111 is 69.84 mm; the length L9 of the second stress release groove 1111 inwardly recessed along the radial direction of the main body 111 is 0.68 mm.

[0084] As can be seen from the above, in the negative electrode current collecting disk 100, L2 / L1=3.8%, L3 / L4=50%, L5 / L6=1.2%, L7 / L8=12%, and L9 / L6=3%.

[0085] Embodiment 2:

[0086] Embodiment 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 100, which differs from Embodiment 1 in that: L2 / L1=6%, α is 35°, L3 / L4=40%, L5 / L6=1%, L7 / L8=8%, and L9 / L6=2%.

[0087] Embodiment 3:

[0088] Embodiment 3 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting plate 100, which differs from Embodiment 1 in that: L2 / L1=8%, α is 45°, L3 / L4=60%, L5 / L6=4%, L7 / L8=16%, and L9 / L6=5%.

[0089] Comparative Example 1:

[0090] Comparative Example 1 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , which is different from Example 1 in that: L2 / L1 = 2%.

[0091] Comparative Example 2:

[0092] Comparative Example 2 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 2 and the embodiment 1 is that L2 / L1 = 12%.

[0093] Comparative Example 3:

[0094] Comparative Example 3 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that α is 25°.

[0095] Comparative Example 4:

[0096] Comparative Example 4 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , which is different from Example 1 in that α is 65°.

[0097] Comparative Example 5:

[0098] Comparative Example 5 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 5 and the embodiment 1 is that L3 / L4=25%.

[0099] Comparative Example 6:

[0100] Comparative Example 6 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 6 and the embodiment 1 is that L3 / L4=65%.

[0101] Comparative Example 7:

[0102] Comparative Example 7 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , and the difference between the comparative example 7 and the embodiment 1 is that L5 / L6=0.05%.

[0103] Comparative Example 8:

[0104] Comparative Example 8 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 8 and the embodiment 1 is that L5 / L6=8%.

[0105] Comparative Example 9:

[0106] Comparative Example 9 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 9 and the embodiment 1 is that L7 / L8=2%.

[0107] Comparative Example 10:

[0108] Comparative Example 10 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, and the difference between the comparative example 1 and the embodiment 1 is that L7 / L8=25%.

[0109] Comparative Example 11:

[0110] Comparative Example 11 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that: L9 / L6=1%.

[0111] Comparative Example 12:

[0112] Comparative Example 12 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that: L9 / L6=8%.

[0113] Comparative Example 13:

[0114] Comparative Example 13 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , which differs from Example 1 in that the first stress release groove 130 is not provided.

[0115] Comparative Example 14:

[0116] Comparative Example 14 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , which differs from Example 1 in that a thinning portion 1121 is not provided.

[0117] Comparative Example 15:

[0118] Comparative Example 15 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100, which is different from Example 1 in that the second stress release groove 1111 is not provided.

[0119] Comparative Example 16:

[0120] Comparative Example 16 provides a cylindrical lithium-ion battery, which includes a negative electrode current collecting disk 100 , which differs from Example 1 in that the first stress release groove 130 , the thinning portion 1121 and the second stress release groove 1111 are not provided.

[0121] In Table 1 below, the height difference ΔH (mm) of the arch of the main body 111, the maximum temperature (T1max) of the welding mark of the flanging 120, the maximum temperature (T2max) of the welding mark on the surface of the main body 111, the number of folding times (C) when the surface of the main body 111 breaks after folding, and the time (t) required for injecting the electrolyte into the battery were tested for the negative current collector plate 100 manufactured in the above-mentioned examples and comparative examples. Among them:

[0122] The specific test method for the height difference ΔH (mm) of the arch of the main body 111 is as follows: The battery is sampled according to the normal process until the welding of the negative current collector plate 100 to the cell wall is completed, and the grooving process is carried out. Before the grooving process, the surface of the negative current collector plate 100 is measured in height with an altimeter. Randomly select 3 points within a circle with the center of the surface of the main body 111 of the negative current collector plate 100 as the center and a radius of 1 mm for height measurement, and take the average value H. After that, the battery grooving equipment tool feeds continuously towards the center of the battery at a speed of 1800 r / min until the grooving depth reaches 3.0 mm, then the battery is taken out. According to the same test method, randomly select three points at the middle position of the surface of the main body 111 of the negative current collector plate 100 to measure the height H, and calculate the height difference of the arch ΔH = H after - H. In the case of stress concentration, ΔH = 0.9 - 1.0 mm.

[0123] The specific test methods for the maximum temperature (T1max) of the welding mark of the flanging 120 and the maximum temperature (T2max) of the welding mark on the surface of the main body 111 are as follows: The negative current collector plate 100 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 wire is passed through the through hole and attached to the welding mark between the flanging 120 of the negative current collector plate 100 and the cell wall and the welding mark between the surface of the main body 111 and the winding core 300 respectively. After injecting the liquid according to the normal battery manufacturing process, the cover plate is sealed and then formation and grading are carried out to make a qualified battery. Charge and discharge are carried out for 10 cycles at a 3C high rate. After 10 cycles of charge and discharge, the temperature data of the welding area collected by the temperature control wire are obtained, and the maximum value Tmax within the temperature fluctuation range within 10 cycles is taken. T1max represents the maximum temperature of the welding mark of the flanging 120, and T2max represents the maximum temperature of the welding mark on the surface of the main body 111.

[0124] The specific test method for the number of folding times (C) when the disk surface of the main body 111 is broken after being folded is as follows: the flange 120 of the negative electrode current collector disk 100 is completely cut off to leave a complete disk surface, and then the negative electrode current collector disk 100 is folded along the central axis formed by the line connecting the midpoint of the flange 120 and the center of the circle, and one half of the surface is completely folded and attached to the other half, and then the folded negative electrode current collector disk 100 is opened to 180°, which is counted as one folding, and then the same method is used to fold it again. Each folding requires that the two half surfaces are completely attached, and then opened to 180° after folding, and repeated multiple times until a break occurs on the disk surface, and the number C is recorded.

[0125] Specific test method for the time (t) required for electrolyte injection into the battery: install the negative electrode collector plate 100 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 pressure for 40 seconds, positive pressure injection is performed, and nitrogen is flushed into the battery. The positive pressure inside the battery gradually becomes 0.8 MPa, and the electrolyte in the liquid holding cup continues to flow into the battery. The height of the electrolyte in the liquid holding cup gradually decreases, and then it is adjusted to negative pressure injection and maintained. Then it is adjusted to positive pressure injection and maintained. 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.

[0126]

[0127]

[0128] As can be seen from Table 1, the range of L2 / L1 is set at 3% to 10%, the range of angle α is set at 30° to 50°, the range of L3 / L4 is set at 30% to 60%, the range of L5 / L6 is set at 1% to 5%, the range of L7 / L8 is set at 5% to 20%, and the range of L9 / L6 is set at 2% to 5%. The height difference △H of the arch of the main body 111 is usually 0.01mm to 0.02mm, the maximum temperature T1max of the weld mark of the flange 120 is usually 102 to 104°C, the maximum temperature T2max of the weld mark of the disk surface of the main body 111 is usually 112 to 115°C, the number of folding times C of the disk surface of the main body 111 after breaking after folding 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 100 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.

[0129] As can be seen from Table 1, if L2 / L1 is too small (the first stress release groove 130 is not recessed enough), the main body 111 of the disc body 110 will be arched to a high height; if L2 / L1 is too large, the maximum temperature of the weld mark of the flange 120 will increase. Therefore, setting L2 / L1 within a reasonable range can balance the arch height of the main body 111 of the disc body 110 of the negative electrode current collector 100 and the maximum temperature of the weld mark of the flange 120.

[0130] As can be seen from Table 1, if the angle α is too small, the height of the disk surface of the main body 111 of the disk body 110 will be too high; if the angle α is too large, the maximum temperature of the weld mark of the flange 120 will increase. Therefore, setting the angle α within a reasonable range can balance the height of the disk surface of the main body 111 of the disk body 110 of the negative electrode current collector 100 and the maximum temperature of the weld mark of the flange 120.

[0131] As can be seen from Table 1, if L3 / L4 is too small (the thinned portion 1121 is too thin), the main body 111 of the negative electrode current collecting disc 100 will be easily broken; if L3 / L4 is too large, the main body 111 of the disc 110 will be arched to a high height. Therefore, setting L3 / L4 within a reasonable range can balance the arched height of the main body 111 of the disc 110 of the negative electrode current collecting disc 100 and the structural strength of the disc 110.

[0132] As can be seen from Table 1, if L5 / L6 is too small (the thinned portion 1121 is too narrow), the main body 111 of the disc body 110 will be too high; if L5 / L6 is too large, the main body 111 of the disc body 110 of the negative electrode current collector 100 will be easily broken. Therefore, setting L5 / L6 within a reasonable range can balance the height of the disc surface arch of the main body 111 of the disc body 110 of the negative electrode current collector 100 and the structural strength of the disc body 110.

[0133] As can be seen from Table 1, if L7 / L8 is too small (the opening of the second stress release groove 1111 is too small), the height of the disk surface of the main body 111 of the disk body 110 will be higher and the electrolyte injection rate will decrease; if L7 / L8 is too large, the maximum temperature of the weld mark of the flange 120 will increase. Therefore, setting L7 / L8 within a reasonable range can balance the height of the disk surface of the main body 111 of the disk body 110 of the negative electrode current collector 100, the electrolyte injection rate and the maximum temperature of the weld mark of the flange 120.

[0134] As can be seen from Table 1, if L9 / L6 is too small (the second stress release groove 1111 is not recessed enough inward), the main body 111 of the disk body 110 will be arched higher and the electrolyte injection rate will be reduced; if L9 / L6 is too large, the maximum temperature of the disk surface weld mark of the main body 111 of the disk body 110 will be higher. Therefore, setting L9 / L6 within a reasonable range can balance the arched height of the disk surface of the main body 111 of the disk body 110 of the negative electrode current collector 100, the electrolyte injection rate and the maximum temperature of the disk surface weld mark of the main body 111 of the disk body 110.

[0135] It can be seen from Table 1 that if the first stress release groove 130 is not provided, the height of the plate surface of the main body 111 of the plate body 110 will be higher. Therefore, providing the first stress release groove 130 is beneficial to controlling the height of the plate surface of the main body 111 of the plate body 110.

[0136] It can be seen from Table 1 that if the thinning portion 1121 is not provided, the height of the plate surface of the main body 111 of the plate body 110 will be higher. Therefore, providing the thinning portion 1121 is beneficial to controlling the height of the plate surface of the main body 111 of the plate body 110.

[0137] As can be seen from Table 1, if the second stress release groove 1111 is not provided, the main body 111 of the disk body 110 will have a higher bulging height and a lower injection efficiency. Therefore, providing the first stress release groove 130 is beneficial to controlling the bulging height of the main body 111 of the disk body 110 and improving the electrolyte injection efficiency.

[0138] It can be seen from Table 1 that if the first stress release groove 130 , the thinning portion 1121 and the second stress release groove 1111 are not provided, the main body 111 of the disk body 110 will be arched higher than when all three are provided.

[0139] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present implementation. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0140] Although examples of the present embodiment have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. A negative electrode current collector for a cylindrical lithium-ion battery, characterized in that: The invention comprises a disk body (110) and a plurality of flanges (120) formed by protruding toward one side along the outer periphery of the disk body (110), wherein the plurality of flanges (120) are used to be fitted and connected with the shell wall of the shell (200) of the cylindrical lithium-ion battery, and the negative electrode current collector disk is also provided with a first stress release groove (130) at the edge, wherein the first stress release groove (130) is formed by the edge of the disk body (110) and the edges of each flange (120) being concave inwardly at the junction area, and the first stress release groove (130) is used for the flange (120) to bend relative to the disk body (110) along the first stress release groove (130).

2. The negative electrode current collector according to claim 1, characterized in that: The arc length of the flange (120) along the circumferential direction of the disc body (110) is L1, the inward concave length of the first stress release groove (130) along the circumferential direction of the disc body (110) is L2, and the range of L2 / L1 is 3% to 10%.

3. The negative electrode current collecting disk according to claim 1 or 2, characterized in that: The bottom of the first stress release groove (130) is located at the junction of the flange (120) and the disk body (110).

4. The negative electrode current collecting disk according to claim 3, characterized in that: The first stress release groove (130) is a V-shaped groove, the V-shaped groove comprises a third side (131) and a fourth side (132), the third side (131) and the fourth side (132) form an angle α, and the range of α is 30° to 50°.

5. The negative electrode current collecting disk according to claim 1 or 2, characterized in that: The disk body (110) comprises a main body (111) and a plurality of connecting parts (112) extending radially outward from the main body (111); the plurality of flanges (120) are connected to the plurality of connecting parts (112) in a one-to-one correspondence; the connecting part (112) comprises a fifth side (1122) and a sixth side (1123) connected to the edge of the main body (111); the connecting part (112) is provided with a thinning part (1121) extending from the fifth side (1122) to the sixth side (1123); the thickness of the thinning part (1121) is less than the thickness of other parts of the connecting part (112).

6. The negative electrode current collecting disk according to claim 5, characterized in that: The thinning portion (1121) is formed by two opposite surfaces of the connecting portion (112) being recessed inwardly along the thickness direction of the connecting portion (112); the thinning portion (1121) includes, from inside to outside along the radial outward direction of the main body (111), a first transition zone (1121a) with a gradually decreasing thickness, a thickness maintaining zone (1121b) with a constant thickness, and a second transition zone (1121c) with a gradually increasing thickness; the thickness of the thickness maintaining zone (1121b) is L3, the thickness of the main body (111) is L4, and the range of L3 / L4 is 30% to 60%.

7. The negative electrode current collecting disk according to claim 6, characterized in that: The length of the thickness maintaining area (1121b) of the thinning portion (1121) along the radial direction of the disk main body (111) is L5, the radius of the main body (111) is L6, and the range of L5 / L6 is 1% to 5%.

8. The negative electrode current collecting disk according to claim 5, characterized in that: The negative electrode current collector is also provided with a second stress release groove (1111) at the edge, the second stress release groove (1111) is formed by the edge of the main body (111) being recessed inwardly, and the edge of the second stress release groove (1111) is connected to the edge of the connecting portion (112).

9. The negative electrode current collecting disk according to claim 8, characterized in that: The total arc length of the main body (111) at the second stress release groove (1111) is L7, and the total arc length of the main body (111) minus the total arc length corresponding to the connecting portion (112) is L8, and the range of L7 / L8 is 5% to 20%.

10. The negative electrode current collecting disk according to claim 8, characterized in that: The inwardly recessed length of the second stress release groove (1111) along the radial direction of the main body (111) is L9, the radius of the main body (111) is L6, and the range of L9 / L6 is 2% to 5%.

11. A cylindrical lithium-ion battery, characterized in that: The invention comprises a shell (200), a winding core (300) and a negative electrode current collector according to any one of claims 1 to 10, wherein the shell (200) is provided with an inwardly recessed rolling groove portion (210) extending circumferentially of the shell (200), the disk body (110) of the negative electrode current collector disk is connected to the negative end of the winding core (300), and the flange (120) of the negative electrode current collector disk is fitted and connected to the shell wall of the rolling groove portion (210) of the shell (200).

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