A cylindrical lithium battery

Abstract

The present application provides a cylindrical lithium battery. The outer shell of the cylindrical lithium battery forms a necking groove, wherein the height H2 of the necking groove is 0.1%-1% of the outer shell height H1, and the radial depth H3 of the necking groove is 5%-10% of the outer shell outer diameter D1. The sum of the areas of all second holes in the positive electrode current collector disk of the cylindrical lithium battery is 0.9-1.5 times the area of ​​the first holes. A fuse groove is formed in the tail portion of the positive electrode current collector disk. The distance between the center of the fuse groove and the end of the tail portion away from the disk portion is 68%-78% of the tail portion length. The minimum cross-sectional area S2 of the tail portion at the location of the fuse groove is 45%-65% of the overall cross-sectional area S1 of the tail portion. The negative electrode current collector disk of the cylindrical lithium battery is provided with a flat elevated platform, and the flatness of the elevated platform surface is 0.01-0.05 mm. By rationally designing the neck portion, the positive electrode current collecting plate, and the negative electrode current collecting plate, the cylindrical lithium battery of the present application achieves a balance in multiple aspects such as liquid injection performance, safety, and weldability, and can improve battery performance.

Description

Technical Field

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

[0002] In related technologies, cylindrical batteries are usually packaged in cylindrical steel shells, and bare cells are made by a winding process to form a cylindrical core. The cap is located on the top of the battery and is connected to the positive electrode in the core through the positive current collecting disk. The steel shell is connected to the negative electrode in the core through the negative current collecting disk. The positive current collecting disk and the negative current collecting disk enable electrons to be transmitted longitudinally from the current collector to the current collecting disk, thereby effectively improving the charge and discharge performance of the cylindrical lithium battery by increasing the current conduction area and shortening the current conduction distance.

[0003] As mentioned above, cylindrical lithium batteries involve multiple structural components and electrical connectors, including steel shells, winding cores, positive electrode current collectors, and negative electrode current collectors. The assembly process also involves multiple processes such as welding and liquid injection. In order to achieve a better assembly effect and optimize the final battery performance, many factors need to be considered in the design of the above components. For example, taking the positive electrode current collector as an example, its electrical transmission performance, electrolyte injection, safety protection when the battery overheats, and welding processability, etc., are important factors. Therefore, how to reasonably design cylindrical lithium batteries so as to achieve a balance in terms of liquid injection performance, safety, and weldability is a problem that needs to be solved urgently. Summary of the Invention

[0004] The embodiments of the present application provide a cylindrical lithium battery to at least solve the technical problems of the existing cylindrical lithium batteries that are unbalanced in terms of assemblability, safety, and battery performance.

[0005] The first embodiment of the present application provides a cylindrical lithium battery, comprising a housing, a cap, a positive electrode current collecting disc, a winding core, and a negative electrode current collecting disc, wherein:

[0006] The winding core has a positive electrode flattening structure and a negative electrode flattening structure relative to each other, wherein the positive electrode flattening structure and the negative electrode flattening structure are both formed by flattening a full-electrode tab cut-and-stacked structure, the positive electrode flattening structure is connected to the cap via the positive electrode current collecting disk, and the negative electrode flattening structure is connected to the outer shell via the negative electrode current collecting disk;

[0007] The shell includes a shell bottom and a side wall, the top end of the side wall has an opening, the side wall is concave inwardly along the circumferential direction near the opening to form a constricted portion, the outer surface of the side wall forms a constricted groove at the constricted portion, the winding core is located in an area defined by the constricted portion and the shell bottom within the shell, the height H2 of the constricted groove is 0.1%-1% of the height H1 of the shell, and the depth H3 of the constricted groove in the radial direction is 5%-10% of the outer diameter D1 of the shell;

[0008] The positive electrode current collector includes a disk body and a tail body that are interconnected. The disk body is connected to the positive electrode flattening structure, and the tail body is connected to the cap. A circular first hole is provided in the center of the disk body, and at least one circular second hole is provided around the periphery of the first hole. The sum of the areas of all the second holes is 0.9-1.5 times the area of ​​the first hole. The tail body is provided with at least one fuse slot. At locations on the tail body other than the fuse slot, the tail body has an overall cross-sectional area S1. The tail body has a minimum cross-sectional area S2 at the location of the fuse slot, and the minimum cross-sectional area S2 is 45%-65% of the overall cross-sectional area S1.

[0009] The negative electrode current collecting plate has a first side and a second side opposite to each other, the first side is connected to the negative terminal, and a flat raised platform is provided at the center of the second side, the raised platform is connected to the inner surface of the shell bottom, and the flatness of the raised platform surface is 0.01-0.05mm.

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

[0011] First, by rationally designing the height and depth of the necking groove on the shell, the internal space utilization of the shell can be effectively improved to increase the energy density of the battery. In addition, the structural strength of the necking part and the sealing processability can also be improved.

[0012] Secondly, by rationally designing the dimensions of the first and second holes in the positive electrode current collector, through which electrolyte penetrates, a balance between injection efficiency and weldable area is achieved, while also ensuring welding safety. Furthermore, the rationally sized fuse slots in the tail section ensure current interruption in the event of thermal runaway, thus achieving a balance between battery safety and low internal resistance in the tail section.

[0013] Furthermore, by providing a flat raised platform on the side where the negative electrode current collecting disk is connected to the inner surface of the shell bottom, the raised platform has a small area, so it can be guaranteed to have good surface flatness. The surface of the raised platform can fit well with the inner surface of the shell bottom, which can effectively avoid welding quality problems such as cold welding between the two.

[0014] In summary, by rationally designing the neck portion, the positive electrode current collecting plate, and the negative electrode current collecting plate, the cylindrical lithium battery of the present application achieves a balance in multiple aspects such as liquid injection performance, safety, and weldability, and can provide improved battery performance.

[0015] In one possible embodiment, the winding core has a winding core hole extending therethrough, and the diameter D4 of the first hole is 1.4-1.8 times the diameter D7 of the winding core hole; the raised platform is circular and located at the center of the second side, and the diameter D9 of the raised platform is 28%-38% of the diameter D8 of the negative electrode current collecting disk.

[0016] By properly designing the diameter range of the first hole, a balance can be achieved between injection efficiency and weldable area, while ensuring welding safety. Furthermore, by properly designing the size of the raised platform, the welding effect and processability of the platform to the shell bottom can be improved.

[0017] In a possible implementation manner, the diameter D3 of the disk body is 80%-95% of the diameter D6 of the winding core; and the diameter D8 of the negative electrode current collecting disk is 90%-98% of the diameter D6 of the winding core.

[0018] By rationally designing the sizes of the positive electrode collector disc and the negative electrode collector disc, the welding area between the two and the winding core can be effectively increased, thereby improving the welding effect and facilitating the design of welding tools.

[0019] In a possible implementation, the diameter D5 of the second hole is 50%-70% of the diameter D4 of the first hole; the height difference H8 between the surface of the raised platform and the surface of the first side is 18%-30% of the thickness T5 of the negative electrode current collecting disk.

[0020] By rationally designing the sizes of the first and second holes in the positive electrode current collector, a balance can be achieved between liquid injection efficiency and welding quality with the positive terminal. Furthermore, by rationally designing the height of the raised platform, the negative electrode current collector not only meets the machinability and usability requirements, but also does not excessively occupy the longitudinal space within the housing, thereby improving the space utilization of the housing.

[0021] In a possible embodiment, the shape of the disk body is a closed axially symmetrical figure composed of a first side, an arc, a second side and a third side connected end to end in sequence, and the shape of the tail body is a closed axially symmetrical figure composed of the third side, a fifth side extending along the length direction of the tail, a fourth side away from the disk body and a sixth side extending along the length direction of the tail connected end to end in sequence, wherein the two ends of the fifth side are respectively connected to the fourth side and the first side, and the two ends of the sixth side are respectively connected to the fourth side and the second side; the raised platform is formed by integral stamping of the negative electrode current collecting disk, a recessed portion is formed on the first side at a position corresponding to the raised platform, and a welding area is formed on the first side around the recessed portion, and the surface of the welding area abuts the negative electrode flattening structure.

[0022] The rational design of the disc body and tail body facilitates the manufacture and assembly of the positive electrode current collector disc. Simultaneously, the negative electrode current collector disc and raised platform are formed through rational stamping, resulting in high dimensional accuracy and excellent surface quality, facilitating welding to the winding core and outer shell.

[0023] In a possible implementation, the length L4 of the tail body is 85%-95% of the diameter D3 of the disk body; the distance L5 between the center of the fuse slot and the end of the tail body away from the disk body is 68%-78% of the length L4 of the tail body.

[0024] By rationally designing the length of the tail body, a balance is achieved between welding processability and battery safety. At the same time, the fuse slot of the tail body is reasonably positioned, allowing the tail body and the cap to be welded smoothly.

[0025] In a possible embodiment, the disc body has a center angle A, and 40°≤∠A≤60°, wherein the center angle A has the center point corresponding to the arc as the vertex, and the two sides pass through the first side away from the endpoint of the arc and the second side away from the endpoint of the arc respectively; the first width W2 of the tail body is W2=D3*sin(∠B / 2), and 20°≤∠B≤40°, wherein ∠B has the center point corresponding to the arc as the vertex, and the two sides pass through the intersection of the fifth side and the sixth side with the full circle in which the arc is located.

[0026] By properly designing the center angle A, the disc body can maintain a large weldable area after the hole is opened. At the same time, by properly designing the width of the tail body, it helps to retain the largest weldable area while ensuring sufficient mechanical strength to prevent breakage during production. It also facilitates the rapid passage of electrons, reducing the internal resistance of the battery.

[0027] In a possible implementation, the second width W3 of the tail body at the fuse slot is 3 / 8-3 / 4 of the first width W2; and the dimension L6 of the fuse slot along the length direction of the tail body is in the range of 0<L6≤W2.

[0028] When the second width W2 is too small, the tail body's strength at the fuse slot is insufficient, making it susceptible to breaking when bent. Conversely, when the second width W2 is too large, the tail body fails to fuse quickly, posing a safety hazard. By properly designing the tail body's width at the fuse slot, a balance can be achieved between the tail body's mechanical properties and the battery's safety performance. Furthermore, if L5 is too large, the tail body's fuse position is difficult to determine, increasing the battery's safety risk. Conversely, if L5 is too small, the tail body's fuse sensitivity increases, potentially causing it to fuse even at safe currents. Properly designing the fuse slot dimensions helps improve battery safety.

[0029] In a possible implementation manner, the included angle θ1 between the fifth side and the first side is 45-90°, and the included angle θ2 between the sixth side and the second side is 45-90°.

[0030] By properly designing the angle θ1 between the fifth side and the first side, and the angle θ2 between the sixth side and the second side, the mechanical properties of the positive electrode current collecting disc and the size of the weldable area of ​​the disc body can be balanced.

[0031] In one possible embodiment, the necking portion includes a first wall portion and a second wall portion extending toward the center of the shell, and the necking portion also includes a connecting portion for connecting the first wall portion and the second wall portion, the outer surfaces of the first wall portion, the second wall portion and the connecting portion jointly define a necking groove, and the first wall portion and the second wall portion are both set at a certain inclination angle to the bottom of the shell; the cap includes a stacked explosion-proof valve plate and a terminal plate, the tail body is connected to the bottom of the terminal plate, and the explosion-proof valve plate is provided with a first notch and a second notch, the first notch is a closed circle connected at both ends, and the second notch is a line segment shape, and the first notch intersects with the second notch.

[0032] By arranging the first and second walls constituting the constricted portion to be inclined toward the bottom of the battery case, a certain amount of collapse margin is reserved for the constricted portion, thereby facilitating the design of the grooves in the preceding grooving step and facilitating the formation of the desired constricted portion structure in the sealing step. Furthermore, by providing the first and second notches in the explosion-proof valve plate, when an abnormal condition such as overheating or a short circuit occurs within the battery, causing a sharp rise in internal pressure, either the pressure in the edge region or the central region reaches a preset value first, and one of the first and second notches ruptures first, thereby enabling timely pressure relief. Furthermore, because the first and second notches intersect, rupture of either the first or second notch will also cause the other to rupture, thereby expanding the opening area of ​​the explosion-proof valve plate and improving the pressure relief effect. Consequently, when the gas pressure within the battery exceeds the preset value, the explosion-proof valve plate can quickly and effectively open to release the pressure, thereby enhancing battery safety.

[0033] In a possible embodiment, the larger of the angles between the first wall portion and the shell bottom and the angles between the second wall portion and the shell bottom is α, and the range of α is α<10°; the explosion-proof valve disc is provided with a thinning portion extending in the radial direction, the first notch is arranged within the radial range where the thinning portion is located, the thickness of the thinning portion is T3, the depth of the first notch is H4, and the range of H4 / T3 is 30%-60%.

[0034] By properly designing the angle α, the difficulty of rolling groove design is reduced while also minimizing the impact of the neck portion on the lower cavity and ensuring a secure seal with the cap. Furthermore, by properly setting the thickness of the thinned portion and the depth of the first notch, the first notch is effectively fractured when the opening conditions are met, allowing the battery to release pressure. This also ensures that the explosion-proof valve disc possesses sufficient strength and rigidity for ease of processing and assembly.

[0035] In a possible implementation manner, the angle α is in the range of 1-5°; the width of the thinned portion is W1, and the range of W1 is 3-8 mm.

[0036] By properly designing the angle α, the difficulty of rolling groove design is reduced while also minimizing the impact of the neck on the lower cavity and ensuring a tight seal on the cap. Furthermore, by properly designing the width of the thinned portion, the first notch effectively breaks when the opening conditions are met, allowing the battery to release pressure. This also ensures that the explosion-proof valve disc has sufficient strength and rigidity for ease of processing and assembly.

[0037] In a possible implementation, the minimum wall thickness of the neck portion is T2, the wall thickness of the side wall is T1, and the range of T2 / T1 is greater than 80%; the diameter D2 of the first notch is equal to the length L2 of the second notch.

[0038] By rationally designing the wall thickness at the thinnest point of the neck, the required compressive strength of the housing can be ensured. Furthermore, by setting the diameter of the first notch equal to the length of the second notch, the second notch divides the first notch into two symmetrical parts, facilitating processing. Furthermore, when the explosion-proof valve is assembled into a cylindrical lithium battery, the second notch is located in the center of the battery, allowing the explosion-proof valve to open smoothly to release pressure.

[0039] In a possible implementation, the range of T2 is 0.1-0.2 mm; the bottoms of the first notch and the second notch are provided with chamfered portions, and the radii of the chamfered portions are the same, and the radius of the chamfered portions is R, and the range of R is 0.05-0.15 mm.

[0040] By properly designing the wall thickness at the thinnest point of the neck, the required compressive strength of the housing can be ensured. Furthermore, by properly setting the radius of the chamfered corners, stress concentration at the bottoms of the first and second notches can be effectively reduced, while also lowering processing difficulty and manufacturing costs.

[0041] In one possible embodiment, the distance L1 between the lowest point of the neck portion and the upper surface of the shell bottom is 90%-98% of the height H1 of the shell; the depth H4 of the first notch is less than the depth H5 of the second notch, and the depth in the middle of the second notch is greater than the depth at both ends.

[0042] By rationally designing the distance between the bottom of the neck and the bottom of the shell, the internal space utilization of the shell can be effectively improved, thereby increasing the energy density of the battery. At the same time, the structural strength of the neck and the sealing processability can be ensured. At the same time, by increasing the depth of the second notch, the impact of the increased thickness of the explosion-proof valve in the middle area on the second notch can be reduced, thereby ensuring that the explosion-proof valve can be opened smoothly at the second notch. Moreover, by setting the depth of the second notch so that the depth in the middle is greater than the depth at both ends, that is, the depth of the second notch is deeper in the middle and shallower at both ends, the impact of the step-by-step thickness change in the middle area of ​​the explosion-proof valve can be reduced, thereby ensuring that the explosion-proof valve can be opened smoothly at the second notch.

[0043] In one possible embodiment, the full-tab stacking structure includes a current collector substrate, which is divided into a material area for coating polar materials and a tab area along the width direction, and the material area and the tab area both extend along the length direction of the current collector substrate. The current collector substrate has a plurality of tabs spaced apart along the length direction at the tab area, and the width of the edge of the tab facing the material area is W4, the distance between the edges of two adjacent tabs facing the material area is W5, the range of W5 / W4 is 20%-30%, and the shape of the tab is a parallelogram, and the angle β between the edge connected to the edge of the tab facing the material area and the width direction of the current collector substrate is 14-18°.

[0044] By optimizing the die-cut tab width W2 and tab spacing W3, and controlling W3 / W2 within the range of 20%-30%, the tab tension is increased, allowing the tab to withstand the pressure of the subsequent flattening operation, reducing the generation of debris, reducing the possibility of debris falling into the battery, and reducing the probability of battery short circuits. In addition, the appropriate tab width W2 and tab spacing W3 structural design can, to a certain extent, ensure that the density of the entire tab after flattening is not too high, and there is a certain effective gap between them, which is conducive to electrolyte infiltration, thereby improving the battery's cycle performance. In addition, by selecting the angle β between the beveled edge of the tab and the width direction of the current collector substrate to be 14-18°, the tab can still fit as closely as possible after flattening, thereby achieving an appropriate density after flattening. This ensures that the tab has sufficient electrolyte infiltration while taking into account the tab's welding performance and reducing the generation of debris particles, thereby improving the battery's safety and cycle performance.

[0045] In one possible embodiment, a connecting area is further provided between the material area and the tab area, the distance between the edge where the tab is connected to the connecting area and the material area is H7, the length of the edge of the tab away from the material area is H6, and the range of H7 / H6 is 10%-20%.

[0046] By setting the connection area and rationally designing the size of the connection area and the tab, the positive electrode flattening structure and the negative electrode flattening structure formed by flattening have good welding performance, overcurrent performance and reliability.

[0047] In a possible implementation, the range of H7 is 0.4-0.6 mm, and the range of W4 is 1.5-2.2 mm.

[0048] By rationally designing the distance between the edge where the tab connects to the connection area and the material area, the problem of outward protrusion of the material area is balanced with the welding effect and the current flow effect. At the same time, by rationally setting the tab width, sufficient tension can be ensured on the tab, reducing chip drop during the leveling process, preventing scattering and chip drop, and improving the leveling effect to ensure welding performance.

[0049] In one possible embodiment, the length of the multiple tabs in the tab area along the length direction of the current collector substrate is less than the length L7 of the material area, one of the two ends of the tab area has a first cut-off area, and the other end has a second cut-off area. The length of the first cut-off area along the length direction of the current collector substrate is L8, and the range of L8 / L7 is 5%-15%. The length of the second cut-off area along the length direction of the current collector substrate is L9, and the range of L9 / L7 is 10%-20%.

[0050] The provision of the first cut-away area or the second cut-away area is beneficial for reducing blockage of the core center hole and preventing the tabs from protruding outward during subsequent winding and flattening, thereby facilitating liquid injection and inserting the core into the shell.

[0051] In a possible implementation, the range of L8 is 105-130 mm, and the range of L9 is 175-205 mm.

[0052] By rationally designing the lengths of the first and second cut-away areas, it is beneficial to reduce the blockage of the center hole of the core and avoid the tabs protruding outward during subsequent winding and flattening, thereby facilitating liquid injection and the insertion of the core into the shell. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments of the present application. 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 any creative work.

[0054] Figure 1 This is an exploded schematic diagram of a cylindrical lithium battery according to an embodiment of the present application;

[0055] Figure 2This is a schematic diagram of the state of the outer shell of a cylindrical lithium battery after being sealed in one embodiment of the present application;

[0056] Figure 3 yes Figure 2 A partial schematic diagram of the middle part;

[0057] Figure 4 This is a schematic cross-sectional view of a cap in a cylindrical lithium battery according to an embodiment of the present application;

[0058] Figure 5 This is a schematic top view of an explosion-proof valve sheet in a cylindrical lithium battery according to an embodiment of the present application;

[0059] Figure 6 yes Figure 5 Schematic cross-sectional view of the middle explosion-proof valve disc;

[0060] Figure 7 yes Figure 6 Partial schematic diagram at point B in the middle;

[0061] Figure 8 yes Figure 6 Partial schematic diagram at point C in the middle;

[0062] Figure 9 1 is a schematic top view of a positive electrode current collecting disk in a cylindrical lithium battery according to an embodiment of the present application, wherein the tail portion is in an expanded state;

[0063] Figure 10 yes Figure 9 Schematic diagram of the structure connecting the positive electrode current collecting disk and the winding core;

[0064] Figure 11 yes Figure 9 A schematic structural diagram of the tail portion of the middle positive electrode current collecting disc;

[0065] Figure 12 yes Figure 11 Schematic diagram of the cross section along the AA direction;

[0066] Figure 13 yes Figure 9 A schematic structural diagram of the tail portion of the middle positive electrode current collecting disc;

[0067] Figure 14 This is a schematic diagram of the structure of the connection between the winding core and the positive electrode current collecting disk and the negative electrode current collecting disk in a cylindrical lithium battery according to an embodiment of the present application;

[0068] Figure 15 This is a schematic diagram of a cylindrical lithium battery cell before winding in one embodiment of the present application;

[0069] Figure 16 Schematic diagram of a full-tab stacking structure of a rolled core in a cylindrical lithium battery according to one embodiment of the present application;

[0070] Figure 17 yes Figure 16 The local schematic diagram of point D in the middle;

[0071] Figure 18 yes Figure 16 Schematic diagram of the flattened structure of the full-element tab;

[0072] Figure 19 yes Figure 18 The local schematic diagram of point E in the middle;

[0073] Figure 20 1 is a schematic structural diagram of a cylindrical lithium battery in accordance with an embodiment of the present invention, in which a negative electrode current collecting disk is connected to a winding core and a shell bottom;

[0074] Figure 21 yes Figure 20 a schematic cross-sectional view of the middle negative electrode current collecting disc;

[0075] Figure 22 yes Figure 21 Partial schematic diagram of point F in the middle.

[0076] Reference numerals:

[0077] 110 - shell, 111 - shell bottom, 112 - side wall, 1121 - neck portion, 1121a - first wall portion, 1121b - second wall portion, 1121c - connecting portion, 1122 - curling edge, 1123 - necking groove, 113 - inner cavity, 1131 - upper cavity, 1132 - lower cavity, 114 - opening;

[0078] 120-cap, 121-top cover, 122-explosion-proof valve disc, 1221a-first notch, 1221b-second notch, 1222-thinning portion, 1223-groove, 1224-welding platform, 123-insulating plate, 124-terminal plate, 125-insulating ring;

[0079] 130 - positive electrode current collecting disc, 131 - disc body, 1311 - first side, 1312 - arc, 1313 - second side, 1314 - third side, 1315 - first hole, 1316 - second hole, 132 - tail body, 1321 - fuse slot, 1322 - fifth side, 1323 - sixth side, 1324 - fourth side;

[0080] 140-winding core, 141-positive electrode flattening structure, 142-negative electrode flattening structure, 143a-first separator, 143b-second separator, 144-current collector substrate, 144a-positive electrode sheet, 144b-negative electrode sheet, 1441-material area, 1442-ear area, 1443-ear, 14431-edge connected to the ear and the connection area, 14432-edge connected to the edge of the ear facing the material area, 14433-edge of the ear away from the material area, 1444-connecting area, 1445-first cut-away area, 1446-second cut-away area, 145-winding core hole;

[0081] 150 - negative electrode current collecting plate, 151 - first side, 1511 - recessed portion, 1512 - welding area, 152 - second side, 1521 - raised platform. DETAILED DESCRIPTION

[0082] Examples of the present embodiment are described in detail below. Examples of the embodiments 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 are not to be construed as limiting the present embodiment.

[0083] 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. They 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. Therefore, they cannot be understood as limitations on this embodiment.

[0084] In the description of this embodiment, "several" means one or more, "many" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of "first" and "second" in the description is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0085] In the description of this embodiment, unless otherwise clearly defined, terms such as setting, installing, and connecting 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.

[0086] The cylindrical lithium batteries provided in the embodiments of the present application include various size series, such as the 21 series (cylindrical lithium batteries with an outer diameter of 21 mm) and the 46 series (cylindrical lithium batteries with an outer diameter of 46 mm), which are not limited here. Figure 1As shown, the cylindrical lithium battery includes a shell 110, a cap 120, a positive electrode current collecting disk 130, a core 140, and a negative electrode current collecting disk 150, wherein the positive terminal of the core 140 is connected to the cap 120 through the positive electrode current collecting disk 130, and the negative terminal of the core 140 is connected to the shell 110 through the negative electrode current collecting disk 150, so that the cap 120 serves as the positive electrode of the cylindrical lithium battery, and the shell 110 serves as the negative electrode of the cylindrical lithium battery, which is used to be electrically connected to external electrical equipment.

[0087] The housing 110 is described in detail below.

[0088] like Figure 1 and Figure 2 As shown, the housing 110 is generally cylindrical and is configured to be closed on the negative electrode side (the lower side in the figure) and open on the positive electrode side (the upper side in the figure). Specifically, the housing 110 includes a housing bottom 111 and a sidewall 112. The housing bottom 111 is circular, and the sidewall 112 extends upward from the edge of the housing bottom 111. The housing bottom 111 and the sidewall 112 together define an inner cavity 113. The top of the sidewall 112 has an opening 114, which is connected to the inner cavity 113.

[0089] It is understood that the inner cavity 113 defined by the housing bottom 111 and the sidewalls 112 is also cylindrical and is used to accommodate the cap 120 (with its top exposed), the positive electrode current collecting disc 130, the winding core 140, and the negative electrode current collecting disc 150, which will be described below. In addition, by configuring the housing 110 to be open at the top, that is, by providing an opening 114 at the top of the housing 110, it is also convenient for the above components to enter the housing 110 through the opening 114.

[0090] It can be understood that the shell bottom 111 is in the shape of a thin circular plate, and the bottom surface of the negative electrode current collecting disk 150 is in contact with the inner surface of the shell bottom 111, thereby forming a conductive connection between the two, thereby conducting the outer shell 110 and the negative electrode of the winding core 140.

[0091] It is understood that the housing 110 can be made of nickel-plated steel, which has advantages such as high compressive strength. Of course, it is not limited to this. For example, an aluminum housing can also be used. The following description uses the nickel-plated steel housing as an example. The nickel-plated steel housing can be punched from steel strips, which is simple to manufacture and easy to mass-produce, effectively reducing costs.

[0092] like Figure 2 and Figure 3As shown, the side wall 112 is concave inwardly at a position close to the opening 114 to form a constricted portion 1121 for sealing the cap 120. The constricted portion 1121 divides the inner cavity 113 into an upper cavity 1131 and a lower cavity 1132. The constricted portion 1121 can be formed by rolling grooves and sealing processes. In addition, during the sealing process, the side wall 112 is concave to form the constricted portion 1121, and a curling edge 1122 is formed at the top. The curling edge 1122 is aligned with the constricted portion. The neck 1121 and the sidewall 112 together seal the cap 120. Specifically, the top surface of the neck 1121, located on one side of the upper chamber 1131, is used to receive the cap 120 and is in contact with the bottom of the cap 120. The inner wall of the sidewall 112 located between the neck 1121 and the curling edge 1122 is in contact with the outer circumference of the cap 120, while the inner wall of the curling edge 1122 is in contact with the top surface of the cap 120. Thus, the cap 120 completely seals the opening 114, sealing the negative electrode current collecting disc 150, the winding core 140, and the positive electrode current collecting disc 130 in the lower chamber 1132, thereby forming a closed electrochemical system within the housing 110.

[0093] Specifically, the neck portion 1121 includes a first wall portion 1121a and a second wall portion 1121b extending toward the center of the inner cavity 113 and parallel to each other, and a connecting portion 1121c for connecting the first wall portion 1121a and the second wall portion 1121b. Figure 2 In the central direction, the first wall portion 1121a is located above the second wall portion 1121b. The first wall portion 1121a and the second wall portion 1121b are connected by a connecting portion 1121c at one end near the center of the inner cavity 113. The outer surfaces of the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c jointly define a necking groove 1123. It can be understood that the inner surface, i.e., the top surface, of the first wall portion 1121a is used to receive the cap 120 and is in contact with the bottom of the cap 120.

[0094] Although the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c are described above as being interconnected, it is understood that the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c are themselves part of the side wall 112. During the sealing process, the side wall 112 undergoes inward plastic deformation at the position corresponding to the constricted portion 1121, thereby forming the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c. In other words, the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c are integral. Of course, in a pre-sealing process, a rolling groove can be cut at this position, for example, by the feed motion of a rolling cutter and the rotational motion of the housing 110, so that during sealing, the rolling groove undergoes plastic deformation to form the desired constricted portion 1121.

[0095] In this embodiment, the first wall portion 1121a and the second wall portion 1121b are both flat-plate shaped and are inclined toward the housing bottom 111 along their concave directions. Specifically, when the first wall portion 1121a and the second wall portion 1121b are parallel to each other, the angle α between the first wall portion 1121a or the second wall portion 1121b and the housing bottom 111 satisfies the following condition: α<10°. It will be appreciated that in this case, since the first wall portion 1121a and the second wall portion 1121b are both flat-plate shaped and parallel to each other, the center plane of the necking groove 1123 defined by the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c is inclined relative to the surface of the housing bottom 111, and the inclination angle is no greater than 10°.

[0096] When the first wall portion 1121a and the second wall portion 1121b are not completely parallel, the angle α between the first wall portion 1121a or the second wall portion 1121b and the housing bottom 111, whichever is larger, satisfies the following: α<10°. It will be appreciated that in this case, because the first wall portion 1121a and the second wall portion 1121b are not completely parallel to each other, the angle α between the first wall portion 1121a and the housing bottom 111 and the angle α between the second wall portion 1121b and the housing bottom 111 are both less than 10°.

[0097] Thus, firstly, by arranging the first wall portion 1121a and the second wall portion 1121b constituting the constricted portion 1121 to be inclined toward the shell bottom 111, a certain amount of downward collapse margin is reserved for the constricted portion 1121. This facilitates the design of the grooves in the preceding grooving process and facilitates the formation of the desired constricted portion structure during the sealing process. Secondly, the inclination angle of the first wall portion 1121a and the second wall portion 1121b does not exceed 10°, and the height of the constricted portion 1121 intruding into the lower cavity 1132 is relatively small, ensuring the effective space of the lower cavity 1132 and also preventing damage to the core pole assembly. Furthermore, since the inclination angle of the first wall portion 1121a and the second wall portion 1121b does not exceed 10°, the top surface of the neck portion 1121 in the inner cavity 113, that is, the top surface of the first wall portion 1121a, is basically horizontal, and its contact area with the bottom surface of the cap 120 is large. There is sufficient compression between the two, the sealing effect is good, and the safety of the lithium battery can be improved.

[0098] Furthermore, in some embodiments, the angle α satisfies the following relationship: 1° < α < 5°. It is understood that the angle α affects the design difficulty of the groove, the utilization rate of the internal space of the housing 110, and the sealing effect on the cap 120. If α is too large, although the groove design is relatively easy, the utilization rate of the internal space of the housing 110 is reduced, and the sealing effect on the cap 120 is impaired. Conversely, if α is too small, the groove design is difficult, and the forming of the constricted portion 1121 is difficult. By properly designing the angle α, the design difficulty of the groove is reduced, the impact of the constricted portion 1121 on the space of the lower chamber 1132 is reduced, and the sealing effect on the cap 120 is ensured.

[0099] In some embodiments, the distance L1 between the lowest point of the constricted neck 1121 in the inner cavity 113 and the upper surface of the shell bottom 111 is taken as L1, and the height of the outer shell 110 is taken as H1. The range of L1 / H1 is 90%-98%, that is, the following is satisfied: 90%≤L1 / H1≤98%. It is understood that if the distance L1 between the lowest point of the constricted neck 1121 and the upper surface of the shell bottom 111 is too large, that is, L1 / H1 is too large, the height of the upper cavity 1131 will be affected, resulting in a poor sealing effect. Conversely, if the distance L1 between the lowest point of the constricted neck 1121 and the upper surface of the shell bottom 111 is too small, that is, L1 / H1 is too small, the height of the lower cavity 1132 will be affected, the height of the outer shell 110 will be wasted, and the energy density of the battery will be reduced. By rationally designing the distance L1 between the lowest point of the neck portion 1121 in the inner cavity 113 and the upper surface of the shell bottom 111, the sealing effect at the seal can be ensured while improving the utilization of the internal space of the shell 110 and increasing the battery energy density.

[0100] Furthermore, in some embodiments, the height of the necking groove 1123 is H2, the height of the outer shell 110 is H1, and the range of H2 / H1 is 0.1%-1%, that is, it satisfies: 0.1%≤H2 / H1≤1%. It is understandable that if the height H2 of the necking groove 1123 is too large, the height of the outer shell 110 will be wasted, resulting in a decrease in the energy density of the lithium battery; conversely, if the height H2 of the necking groove 1123 is too small, the stress at the connecting portion 1121c will easily concentrate, and the necking portion 1121 will be at risk of breaking at this position, and the sealing process will also be more difficult, resulting in a decrease in the yield rate. By reasonably designing the height H2 of the necking groove 1123, while ensuring that the structural strength of the necking portion 1121 meets the requirements, the utilization rate of the internal space of the outer shell 110 and the processability of the sealing process can also be effectively improved. It is also understandable that if Figure 3As shown, the height H2 described here refers to the height at the opening of the necking groove 1123. Of course, if the first wall portion 1121a and the second wall portion 1121b are arranged to be parallel, the height inside the necking groove 1123 is consistent with the height H2. More preferably, 0.2% ≤ H2 / H1 ≤ 0.5%.

[0101] In some embodiments, the radial depth of the necking groove 1123 is H3, the outer diameter of the housing 110 is D1, and the range of H3 / D1 is 5%-10%, that is, 5%≤H3 / D1≤10%. It is understandable that if the depth H3 of the necking groove 1123 is too large, that is, H3 / D1 is too large, the necking portion 1121 will excessively invade the inner cavity 113 in the radial direction, causing the inner diameter of the inner cavity 113 at the necking portion 1121 to become smaller, resulting in space waste, and also causing the structural rigidity of the necking portion 1121 itself to weaken, stress to increase, and there is a risk of cracking, which in turn makes the sealing unable to be guaranteed; conversely, if the depth H3 of the necking groove 1123 is too small, that is, H3 / D1 is too small, the cap 120 cannot be stably supported by the first wall portion 1121a, and the dimensional chain matching between the two is poor. When sealing, the cap 120 may directly pass through the slot defined by the necking portion 1121 and enter the lower cavity 1132. By properly designing the depth H3 of the necking groove 1123 , while ensuring that the cap 120 can be stably supported by the first wall portion 1121 a for smooth sealing, the utilization rate of the internal space of the shell 110 can be improved, further increasing the energy density of the lithium battery.

[0102] It is understood that during the sealing process, the wall thicknesses of the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c will change as the material undergoes plastic deformation. To ensure the compressive strength of the housing 110, in some embodiments, the minimum wall thickness of the constricted portion 1121 is denoted as T2, and the wall thickness of the housing 110 is denoted as T1, where T2 / T1 ≥ 80%, and more preferably, T2 / T1 ≥ 85%. It is understood that this minimum wall thickness T2 may occur on any of the first wall portion 1121a, the second wall portion 1121b, and the connecting portion 1121c. It is also understood that if T2 / T1 is less than 80%, the mechanical strength margin of the housing 110 may be insufficient. For example, if the internal pressure of the housing 110 increases, the housing 110 may tear at that location. By properly designing the wall thickness T2 at the thinnest point of the constricted portion 1121, the compressive strength of the housing 110 can be ensured to meet the required requirements.

[0103] In some embodiments, to ensure the compressive strength of the housing 110, the minimum wall thickness of the constricted portion 1121 is T2, and the range of T2 is between 0.1-0.2 mm, that is, the following is satisfied: 0.1 mm ≤ T2 ≤ 0.2 mm. It will be appreciated that setting the minimum wall thickness T2 of the constricted portion 1121 between 0.1-0.2 mm allows the constricted portion 1121 to meet the compressive strength requirements of housings 110 with common wall thicknesses. For example, for a housing 110 with a wall thickness of 0.2 mm, the minimum wall thickness T2 of the constricted portion 1121 can be 0.17 mm.

[0104] The cap 120 is described in detail below.

[0105] It can be understood that the cap 120 and the outer shell 110 together serve as a physical barrier to isolate the active materials of the cylindrical lithium battery from the outside world, and when the gas pressure inside the battery exceeds a preset value, the explosion-proof valve 122 of the cap 120 opens to release the pressure to prevent the battery from deforming, bulging, or even burning or exploding.

[0106] like Figure 4 As shown, the cap 120 includes a top cover 121, an explosion-proof valve plate 122, an insulating plate 123, a terminal plate 124, and an insulating ring 125 located on the outer edge, wherein the top cover 121, the explosion-proof valve plate 122, and the terminal plate 124 are stacked in sequence from top to bottom, and are electrically connected to each other. After the cap 120 is sealed and connected to the outer shell 110, the top cover 121 is exposed outside the outer shell 110, and serves as a positive terminal for electrically connecting to the positive electrode of an external electrical device. The bottom surface of the terminal plate 124 is connected to the positive current collecting disc 130, for example, the positive current collecting disc 130 and the terminal plate 124 are welded, thereby forming a conductive connection between the two, thereby connecting the top cover 121 to the positive end of the winding core 140. The explosion-proof valve plate 122 that constitutes the cap 120 is described in detail below.

[0107] refer to Figures 5 and 6 The explosion-proof valve disc 122 is a single component made of aluminum, and is in the shape of a circular thin disc or thin plate. Along the thickness direction, it has a top surface and a bottom surface that are separated from each other. After being assembled into the cylindrical lithium battery, the bottom surface ( Figure 6 The lower middle part) faces the side of the winding core 140, and the top surface ( Figure 6The explosion-proof valve disc 122 is provided with a notch assembly 1221 on one side of the top surface. The notch assembly 1221 includes a first notch 1221a in the shape of a ring and a second notch 1221b extending in the shape of a line segment. The second notch 1221b is located in the area defined by the first notch 1221a, and the two ends of the second notch 1221b are connected to the first notch 1221a, that is, the first notch 1221a presents a closed figure connected end to end. The first notch 1221a is preferably a closed circle, and the second notch 1221b is in the shape of a line segment. When the internal pressure of the cylindrical lithium battery exceeds a preset value, at least one of the first notch 1221a and the second notch 1221b breaks, causing the explosion-proof valve disc 122 to open. In addition, the first notch 1221a and the second notch 1221b that breaks first can drive the other to break as well.

[0108] It can be understood that, since the explosion-proof valve disc 122 of the embodiment of the present application is provided with a first annular notch 1221a and a second line-segment-shaped notch 1221b on the explosion-proof valve disc 122, and both ends of the second notch 1221b are connected to the first notch 1221a, therefore, when an abnormal state such as overheating or short circuit occurs inside the battery, causing the internal air pressure to rise sharply, when the air pressure value in the edge area reaches the preset value first, the first notch 1221a will break first, and the gas inside the battery will rush out from the gap created by the break of the first notch 1221a to release the pressure in time, and the first notch 1221a will also drive the second notch 1221b in the process of breaking. It also breaks, thereby expanding the opening area of ​​the explosion-proof valve plate 122 and improving the pressure relief effect; and when the air pressure value in the middle area reaches the preset value first, the second notch 1221b breaks first, and the gas inside the battery rushes out from the gap caused by the rupture of the second notch 1221b to release the pressure in time, and the second notch 1221b will also drive the first notch 1221a to break during the process of breaking and opening, thereby expanding the opening area of ​​the explosion-proof valve plate 122 and improving the pressure relief effect. Therefore, when the gas pressure inside the battery exceeds the preset value, the explosion-proof valve plate 122 can be opened quickly and effectively to release the pressure, thereby improving the safety of the battery.

[0109] It should be noted that if the first notch 1221a and the second notch 1221b are not connected, they may only break separately and form a gap to release pressure, which is not effective and cannot achieve the purpose of quickly and effectively releasing pressure from the battery as proposed in this application. Therefore, in the embodiment of the present application, the first notch 1221a and the second notch 1221b constituting the notch assembly 1221 are arranged to be connected, that is, they intersect. Therefore, after either one breaks, it can extend to the other, causing the other to also break. Therefore, the opening area of ​​the explosion-proof valve plate 122 can be expanded, thereby quickly releasing pressure from the battery.

[0110] It is understandable that although a more complex internal notch, such as a cross-shaped notch, can be used to replace the second notch 1221b to achieve the purpose of timely explosion when the pressure in the middle area of ​​the battery increases, this will significantly increase the difficulty of processing the explosion-proof valve plate 122, thereby resulting in a decrease in the yield rate and an increase in cost. The embodiment of the present application only provides a straight second notch 1221b inside the explosion-proof valve plate 122, which can effectively achieve rapid and effective pressure relief for the battery while being easy to process and low in cost, and has better economic benefits.

[0111] It can be understood that the first notch 1221a and the second notch 1221b are structures formed on the explosion-proof valve sheet 122 by removing material. Therefore, the explosion-proof valve sheet 122 is thinner at the positions where the first notch 1221a and the second notch 1221b are located relative to the other positions. When the internal pressure of the battery increases and exceeds the preset value, according to the specific pressure position distribution, one of the first notch 1221a and the second notch 1221b or both of them will be deformed as a whole. When the deformation accumulates to a certain extent, the first notch 1221a and the second notch 1221b will be broken, and the broken material will be flipped under the influence of pressure to form a gap at the fracture, and the high-pressure gas inside the battery will be released through the gap.

[0112] In some embodiments, as Figure 5 As shown, the first notch 1221a is circular, and the second notch 1221b is set to pass through the center of the first notch 1221a, that is, the second notch 1221b is exactly the diameter of the annular figure displayed by the first notch 1221a. In this way, if the diameter of the first notch 1221a is D2 and the length of the second notch 1221b is L2, then L2=D2 is satisfied. As a result, the second notch 1221b divides the first notch 1221a into two symmetrical parts, which facilitates the processing and construction of the first notch 1221a and the second notch 1221b. In addition, after the explosion-proof valve plate 122 is assembled to the cylindrical lithium battery, the second notch 1221b is located in the middle area of ​​the cylindrical lithium battery, so that the explosion-proof valve plate 122 can be opened smoothly to release pressure. Furthermore, it can be understood that in order to facilitate the formation of the annular first notch 1221 a and the segment-shaped second notch 1221 b , the first notch 1221 a can be arranged to be co-centered with the explosion-proof valve disc 122 .

[0113] like Figure 6As shown, in some embodiments, the explosion-proof valve disc 122 has a thinned portion 1222 extending in the radial direction, and the first notch 1221a is disposed within the radial range of the thinned portion 1222. Specifically, the thinned portion 1222 can be implemented by providing a groove 1223 on one side of the explosion-proof valve disc 122. The thinned portion 1222 effectively causes the notch assembly 1221 to break when the opening condition is met, thereby releasing battery pressure. It also ensures that the explosion-proof valve disc 122 has sufficient strength and rigidity to facilitate processing and assembly.

[0114] like Figure 7 and Figure 8 As shown, relative to the surface of explosion-proof valve disc 122, first notch 1221a has a depth H4, and second notch 1221b has a depth H5. It is understood that if H4 and H5 are large, i.e., if first notch 1221a and second notch 1221b are deeper, first notch 1221a and second notch 1221b are more likely to break, resulting in an underpressure. If H4 and H5 are large, i.e., if first notch 1221a and second notch 1221b are shallower, first notch 1221a and second notch 1221b are less likely to break, resulting in an overpressure, which can prevent timely release of gas from the battery and increase safety risks. Therefore, in some embodiments, the ratio of the depth H4 of first notch 1221a to the thickness T3 of thinned portion 1222 is between 30% and 60%, satisfying the following conditions: 30% ≤ H1 / T1 ≤ 60%, and more preferably, 40% ≤ H1 / T1 ≤ 55%. The specific values ​​of H4 and H5 can be determined according to the opening pressure and the thickness of the thinned portion 1222 (or the explosion-proof valve plate 122).

[0115] It can be understood that the first notch 1221a and the second notch 1221b are arranged at different positions on the explosion-proof valve plate 122. Specifically, the first notch 1221a is arranged in a ring shape around the center of the explosion-proof valve plate 122 on the end face of the explosion-proof valve plate 122, while the second notch 1221b is radially constructed on the end face of the explosion-proof valve plate 122 through the center of the explosion-proof valve plate 122. Due to strength, installation and other requirements, the thickness of the explosion-proof valve plate 122 in different radial areas is usually different. For example, the wall thickness of the inner part of the explosion-proof valve plate 122 adjacent to the thinning portion 1222 is thicker than that of the thinning portion 1222, and the wall thickness changes in a step-by-step manner and forms a thicker welding platform 1224 in the middle. The explosion-proof valve plate 122 is welded to the terminal plate 124 through the welding platform 1224. Therefore, in order to ensure that the first notch 1221a and the second notch 1221b located in different areas of the explosion-proof valve plate 122 can both open smoothly when the pressure reaches a preset value, in some embodiments, the depth of the first notch 1221a is different from the depth of the second notch 1221b.

[0116] Furthermore, in some embodiments, the depth H4 of the first notch 1221a is less than the depth H5 of the second notch 1221b. By increasing the depth of the second notch 1221b, the effect of the increased thickness of the explosion-proof valve disc 122 in the middle region on the second notch 1221b can be reduced, thereby ensuring that the explosion-proof valve disc 122 opens smoothly at the second notch 1221b.

[0117] Furthermore, the depth of the second notch 1221b is set to be deeper in the middle and shallower at both ends. By setting the depth of the second notch 1221b to be deeper in the middle and shallower at both ends, the effect of the step-wise change in the thickness of the explosion-proof valve disc 122 along the radial direction can be reduced, thereby ensuring that the explosion-proof valve disc 122 opens smoothly at the second notch 1221b.

[0118] Further, in order to reduce stress concentration and reduce the risk of accidental breakage of the first notch 1221a and the second notch 1221b, continue to refer to Figure 7 and Figure 8 The bottoms of the first notch 1221a and the second notch 1221b are both provided with chamfered portions. Providing chamfered portions at the bottoms of the first notch 1221a and the second notch 1221b can reduce stress concentration at the bottoms of the first notch 1221a and the second notch 1221b, thereby reducing the risk of accidental opening of the explosion-proof valve disc 122 when the pressure value does not reach the preset value.

[0119] Furthermore, the radii of the chamfers provided at the bottom of the first notch 1221a and the second notch 1221b are the same. By setting the radii of the chamfers of the first notch 1221a and the second notch 1221b to be the same, the design and manufacturing costs can be reduced. For example, the radius of the chamfers at the bottom of the first notch 1221a and the second notch 1221b is R, and the range of R is between 0.05-0.15mm, that is, it satisfies: 0.05mm≤R≤0.15mm, and more preferably, 0.05mm≤R≤0.1mm. The radius of the chamfers is within this range, which can firstly effectively reduce the stress concentration at the bottom of the first notch 1221a and the second notch 1221b, and secondly, it is easy to process through a mold, which can reduce costs.

[0120] The positive electrode current collecting disk 130 is described in detail below.

[0121] like Figure 9 and Figure 10As shown, the positive electrode current collecting disc 130 includes a disc body 131 and a tail body 132 that are interconnected. The disc body 131 is used to connect to the positive end of the winding core 140, and the tail body 132 is used to connect to the cap 120, so as to form a passage between the winding core 140 and the cap 120. In the present application, the connection between the disc body 131 and the winding core 140 and the connection between the tail body 132 and the cap 120 can adopt any connection method familiar to those skilled in the art, such as welding. The connection between the tail body 132 and the disc body 131 can be any fixed connection method. To ensure a stable connection and structural strength, an integral connection is preferably used.

[0122] like Figure 9 As shown, in order to match the circular cross-section of the winding core 140 and facilitate welding between the disc body 131 and the winding core 140, the shape of the disc body 131 is a closed axisymmetric figure composed of a first side 1311, an arc 1312, a second side 1313 and a third side 1314 connected end to end, and the tail body 132 includes a fifth side 1322 and a sixth side 1323 along its length direction, and a fourth side 1324 away from the disc body 131, the two ends of the fifth side 1322 are respectively connected to the fourth side 1324 and the first side 1311, and the two ends of the sixth side 1323 are respectively connected to the fourth side 1324 and the second side 1313. Figure 9 From the perspective of the tail body 132, the tail body 132 is also a closed axisymmetric figure extending from one end of the disc body 131. It should be noted that the third side 1314 is a virtual edge line proposed for the convenience of describing the disc body 131. There is no such edge in the actual product. Figure 9 Use dotted lines to mark them for distinction. Figure 1 and Figure 10 It can also be understood that when the positive electrode current collecting disc 130 is assembled to the cylindrical lithium battery, the tail body 132 is bent and its distal end is located above the closed axisymmetric figure formed by the disc body 131.

[0123] To improve electrolyte injection efficiency during battery production, the disc body 131 typically has holes for electrolyte passage. To ensure that the solid area of ​​the disc body 131 after the holes are punched still accounts for at least 75% of the total area of ​​the disc body 131, facilitating welding to the winding core 140, the disc body 131 has a central angle A, with 40°≤∠A≤60°, and more preferably 45°≤∠A≤55°. Specifically, the total area of ​​the above-mentioned disc body 131 is the sum of the solid area of ​​the disc body 131 and the hole area; the central angle A takes the center of the circle corresponding to the arc 1312 as the vertex, and the two sides pass through the end point of the first side 1311 away from the arc 1312 and the end point of the second side 1313 away from the arc 1312 respectively. It can be understood that the end point of the first side 1311 away from the arc 1312 and the end point of the second side 1313 away from the arc 12 are also the connection points of the first side 1311, the second side 1313 and the tail body 132.

[0124] In some embodiments, the diameter D3 of the disk body 131 is 80%-95% of the diameter D6 of the winding core 140, where the diameter D3 of the disk body 131 refers to the longest line segment between two points on the arc 1312, and the diameter D6 of the winding core 140 refers to the diameter of the circular cross-section of the winding core 140. Depending on actual needs, the diameter D3 of the disk body 131 can be, for example, 15-23 mm. The disk body 131 within the preferred diameter range ensures a large contact area between the disk body 131 and the winding core 140, increasing the weldable area and expanding the adaptability range of the welding wire length and shape. It can also be understood that when the contact area of ​​the negative electrode current collecting disc 150 is large, within the above-mentioned diameter range, the positive electrode current collecting disc 130 will not become a bottleneck that limits the charge and discharge performance of the cylindrical lithium battery.

[0125] In some embodiments, a first hole 1315 is provided at the center of the disc body 131 for injecting electrolyte into the battery. The center of the disc body 131 may be the center of the circle corresponding to the arc 1312. The winding core 140 is manufactured using a winding process. After winding, a circular winding core hole 145 is formed at the center of the winding core 140. To match the shape of the winding core hole 145, the shape of the first hole 1315 is preferably circular.

[0126] In some embodiments, the diameter D4 of the first hole 1315 is 1.4-1.8 times the diameter D7 of the core hole 145 of the core 140. Depending on actual needs, the diameter D4 of the first hole 1315 is, for example, 4-8 mm. The first hole 1315 can achieve a balance between injection efficiency and weldable area within this diameter range while ensuring welding safety. If the diameter D4 of the first hole 1315 is too small, it will be detrimental to the infiltration of the injection liquid, and when the resistance welding process is used at the bottom of the battery, the electrode head extending into the core hole 145 of the core 140 may produce undesirable contact with the collecting disk, posing an interference risk; if the diameter D4 of the first hole 1315 is too large, the weldable area is correspondingly reduced, limiting the welding processability between the disk body 131 and the core 140.

[0127] In some embodiments, the diameter D4 of the first hole 1315 is 25%-35% of the diameter D3 of the disk body 131. Depending on actual needs, the diameter D4 of the first hole 1315 is, for example, 4-8 mm. The first hole 1315 can achieve a balance between injection efficiency and weldable area within this diameter range while ensuring welding safety. If the diameter D4 of the first hole 1315 is too small, it will be detrimental to the infiltration of the injection liquid, and when the resistance welding process is used at the bottom of the battery, the electrode head extending into the core hole 145 of the winding core 140 may produce undesirable contact with the collecting disk, posing an interference risk; if the diameter D4 of the first hole 1315 is too large, the weldable area is correspondingly reduced, limiting the welding process between the disk body 131 and the winding core 140.

[0128] In some embodiments, at least one second hole 1316 is provided around the first hole 1315 to assist in electrolyte infiltration. Preferably, the second hole 1316 is a circular hole. Further preferably, the area of ​​a single second hole 1316 is 0.3-0.5 times the area of ​​the first hole 1315, and the sum of the areas of all second holes 1316 is 0.9-1.5 times the area of ​​the first hole 1315. If the area of ​​the second hole 1316 is too small compared to the area of ​​the first hole 1315, the auxiliary infiltration effect will be insignificant; if the area of ​​the second hole 1316 is too large, the weldable area of ​​the disc body 131 will be greatly reduced, affecting the connection between the disc body 131 and the winding core 140.

[0129] In some embodiments, the distance L3 between the center of the second hole 1316 and the center of the first hole 1315 is 25%-35% of the diameter D3 of the disk body 131. Depending on actual needs, L3 is, for example, 4.5-7 mm. By rationally designing the distance L2 between the second hole 1316 and the first hole 1315, it helps to improve the electrolyte infiltration effect while ensuring the area of ​​the weldable area. If the distance L3 between the second hole 1316 and the first hole 1315 is too small, the electrolyte infiltration effect cannot be significantly improved; if the distance L3 between the second hole 1316 and the first hole 1315 is too large, the second hole 1316 is too close to the edge of the disk body 131, thereby restricting the battery pack. If the pack blocks the second hole 1316, the electrolyte cannot be injected through the second hole 1316.

[0130] To facilitate processing and improve yield, in a preferred embodiment, the diameter D5 of the second hole 1316 is 50%-70% of the diameter D4 of the first hole 1315. For example, the diameter D5 of the second hole 1316 is 2-4.8 mm. If the diameter D5 of the second hole 1316 is smaller than the preferred diameter range, the wetting assistance function is difficult to achieve. If the diameter D5 of the second hole 1316 is larger than the preferred diameter range, the weldable area of ​​the disc body 131 is reduced. It is understood that the number of second holes 1316 can be determined based on the actual welding process. The number of welding areas is n, and the number of second holes 1316 is n-1, where n ≥ 2.

[0131] The following further describes the disc body 131 with reference to embodiments and comparative examples. The following embodiments and comparative examples of this application are designed with reference to ordinary 21 series cylindrical lithium batteries.

[0132] Example 1:

[0133] Example 1 provides a cylindrical lithium battery, which includes a housing 110, a cap 120, a positive electrode current collecting disc 130, a winding core 140, and a negative electrode current collecting disc 150. The positive electrode current collecting disc 130 includes a disc body 131 and a tail body 132 that are connected to each other, wherein the disc body 131 is connected to the positive end of the winding core 140, and the tail body 132 is connected to the cap 120. A first circular hole 1315 is provided at the center of the disc body 131, and a plurality of second circular holes 1316 are provided around the periphery of the first hole 1315. In addition, the shape of the disc body 131 is a closed axially symmetrical figure composed of a first side 1311, an arc 1312, a second side 1313, and a third side 1314 connected end to end, and has a central angle B.

[0134] Among them, the diameter D6 of the core 140 is 20 mm; the diameter D3 of the disk body 131 is 85% of the diameter D6 of the core 140; the diameter D4 of the first hole 1315 is 30% of the diameter D3 of the disk body 131; the diameter D5 of the second hole 1316 is 60% of the diameter D4 of the first hole 1315; the sum of the areas of all second holes 1316 is 1.2 times the area of ​​the first hole 1315; the distance L3 between the center position of the second hole 1316 and the center of the first hole 1315 is 30% of the diameter D3 of the disk body 131; the center angle B of the disk body 131 is 35°.

[0135] Comparative Example 1:

[0136] Comparative Example 1 provides a cylindrical lithium battery, which differs from Example 1 in that the sum of the areas of all second holes 1316 is 0.4 times the area of ​​the first holes 1315 .

[0137] Comparative Example 2:

[0138] Comparative Example 2 provides a cylindrical lithium battery, which differs from Example 1 in that the diameter D4 of the first hole 1315 is 10% of the diameter D3 of the disc portion 131 .

[0139] Table 1 below evaluates the electrolyte infiltration effect of the cylindrical lithium batteries in the sealed state produced in the above embodiments and comparative examples. The specific electrolyte infiltration test method is: sampling the outer shell 110, the cap 120, the positive electrode current collecting disc 130, the winding core 140, the negative electrode current collecting disc 150 and the electrolyte, welding the positive electrode current collecting disc 130, the negative electrode current collecting disc 150 and the winding core 140, and after placing the assembly into the outer shell 100, welding the cap 120 to obtain an unsealed cylindrical lithium battery. Next, the cylindrical lithium battery is placed in the liquid injection equipment for liquid injection, and the injection volume is 6.8g. After the positive and negative pressure cycles of the equipment, the cylindrical lithium battery is mechanically sealed. After the battery is left to stand for 1 hour, the cylindrical lithium battery is disassembled, the winding core 140 is taken out and unfolded, and placed on the CCD detection equipment for photography, depicting the infiltration area, starting the equipment program to calculate the infiltration area S0, setting the total area of ​​the electrode to S, and the infiltration rate is S0 / S.

[0140] Table 1

[0141] Example 1 Comparative Example 1 Comparative Example 2 Infiltration rate (%) 90.574％ 82.367％ 71.546％

[0142] It can be seen from Table 1 that when the ratio of the sum of the areas of all the second holes 1316 to the area of ​​the first holes 1315 is 1.2 times, and the diameter D4 of the first holes 1315 is 30% of the diameter D3 of the disk body 131, the electrolyte infiltration effect of the core 140 is better. If the ratio of the sum of the areas of all the second holes 1316 to the area of ​​the first holes 1315 is too low, or the first holes 1315 are too small, the electrolyte infiltration effect of the core 140 will deteriorate.

[0143] Continue to refer Figure 9 In some embodiments, at least one fuse slot 1321 is provided on the tail body 132. By designing the fuse slot, the width of the tail body 132 at the fuse slot 1321 is reduced. When the battery thermally runs away, the current converges there, the heat rises and reaches the melting point, causing the tail body 132 to melt, thereby achieving the current cutting-off effect. Specifically, the shape of the fuse slot 1321 can be any shape such as a trapezoid, rectangle, U-shape, V-shape, semicircle, etc. This application does not limit the number of fuse slots 1321, and the accompanying drawings exemplarily show two symmetrically arranged fuse slots 1321. When there are multiple fuse slots 1321, all fuse slots 1321 can be of the same shape or of different shapes. In principle, the setting of the fuse slot 1321 must ensure both the fusing effect and the mechanical strength of the tail body 132.

[0144] In some embodiments, as Figure 11 As shown, the distance L5 between the center of the fuse slot 1321 and the end of the tail portion 132 away from the disk portion 131 is 68%-78% of the length L4 of the tail portion 132. Depending on actual needs, the distance between the center of the fuse slot 1321 and the end of the tail portion 132 away from the disk portion 131 can be, for example, 8-18 mm. If the shape of the fuse slot 1321 is simple, the center of the fuse slot 1321 can be a position commonly recognized by those skilled in the art. For example, for a trapezoidal or rectangular fuse slot 1321, the center can be the intersection of two diagonals. For a semicircular fuse slot 1321, the center can be the center of the circle. If the shape of the fuse slot 1321 is more complex or irregular, the center of the fuse slot 1321 is the geometric center of the shape, that is, the average position of all points within the shape. This can be determined by any method known to those skilled in the art, such as integration, discrete point method, graph segmentation method, etc., or directly calculated using software tools. The length L4 of the tail body 132 is the distance between the connection point between the tail body 132 and the disk body 131 and the end of the tail body 132 away from the disk body 131. The fuse slot 1321 is set in a reasonable position to enable smooth welding of the tail body 132 and the cap 120, while ensuring that the current is cut off in the event of thermal runaway of the battery. If the distance between the fuse slot 1321 and the end of the tail body 132 away from the disk body 131 is too small, the fuse slot 1321 will be too close to the welding position, and the welding of the tail body 132 and the cap 120 will be interfered with; conversely, if the distance between the fuse slot 1321 and the disk body 131 is closer, the current path at the fuse slot 1321 will be larger, and if there is an overcurrent, the fuse will not be able to be blown in time, increasing the safety risk of the battery.

[0145] In some embodiments, to improve battery safety, the length L4 of the tail portion 132 is 85%-95% of the diameter D3 of the disc portion 131. Depending on actual needs, the length of the tail portion 132 can be, for example, 12-20 mm. Within the preferred length range, the tail portion 132 can ensure smooth welding with the cap 120 while also ensuring battery safety. If the length of the tail portion 132 is too short, the tail portion 132 will not extend sufficiently beyond the housing 110 after a single bend, preventing welding to the cap 120. If the length of the tail portion 132 is too long, the end of the tail portion 132 away from the disc portion 131 will contact the housing 110 when the cap 120 is closed and bent a second time, causing a battery short circuit. This will also occupy internal battery space, affecting the placement and proper operation of other components.

[0146] For the convenience of bending and welding, the tail body 132 is usually in the shape of a long strip. In some embodiments, as described above, the tail body 132 has a first width W2, which satisfies: W2 = D3*sin(∠B / 2), where D3 is the diameter of the disc body 131, which refers to the longest line segment between two points on the arc 1312. According to actual needs, the diameter of the disc body 131 is, for example, 15-23 mm; In addition, the center angle B is the vertex of the circle corresponding to the arc 1312, and the two sides pass through the intersection of the fifth side 1322 and the sixth side 1323 of the tail body 132 with the full circle of the arc 1312 (refer to Figure 9 ), for example, and 20°≤∠B≤40°. A larger first width W2 of the tail portion 132 results in a smaller weldable area of ​​the disc portion 131. A reasonable width design helps maximize the weldable area while ensuring sufficient mechanical strength for the tail portion 132 to prevent breakage during production. This also facilitates rapid electron flow and reduces the internal resistance of the battery.

[0147] In some embodiments, the tail portion 132 has a second width W3 at the fuse slot 1321, and 3W2 / 8≤W3<3W2 / 4, meaning that the second width W3 is 3 / 8 to 3 / 4 of the first width W2. The second width W3 in this application refers to the change in the width of the tail portion 132 relative to the first width W2 due to the design of the fuse slot 1321. Based on this application's definition of the second width W3, the first width W2 in this application also refers to the width of the tail portion 132 at locations other than the fuse slot 1321. The second width W2 of the tail portion 132 at the fuse slot 1321, within a reasonable range, can balance the mechanical properties of the tail portion 132 and the safety performance of the battery. If the second width W3 is too small, the tail portion 132 may be insufficiently strong at the fuse slot 1321 and easily break when bent.

[0148] In some embodiments, the dimension L6 of the fuse slot 1321 along the length of the tail portion 132 satisfies the following: 0 < L6 ≤ W2, meaning the vertical length of the fuse slot 1321 does not exceed the first width W2 of the tail portion 132. Preferably, W2 / 4 < L6 ≤ 3W2 / 4, meaning the dimension L6 is between 1 / 4 and 3 / 4 of the first width W2. In this application, the dimension of the fuse slot 1321 along the length of the tail portion 132 refers to the length from the end of the fuse slot 1321 closest to the disc portion 131 to the end farthest from the disc portion 131. A reasonable dimension of the fuse slot 1321 along the length of the tail portion 132 helps improve battery safety. If this dimension is too large, the fuse location of the tail portion 132 is difficult to determine, thereby increasing battery safety risks. Conversely, if this dimension is too small, the fuse sensitivity of the tail portion 132 increases, potentially causing it to fuse even at safe currents.

[0149] In some embodiments, as Figure 12 As shown, the minimum cross-sectional area S2 of the tail body 132 at the fuse slot 1321 is 45%-65% of the overall cross-sectional area S1 of the tail body 132. Specifically, the minimum cross-sectional area S2 of the tail body 132 at the fuse slot 1321 is the cross-sectional area at the narrowest position of the fuse slot 1321, for example, Figure 12 As shown, when the cross-section at this location is square, its cross-sectional area S2 = W3 * T4. The overall cross-sectional area S1 of the tail body 132 is the cross-sectional area of ​​the tail body 132 excluding the fuse slot 1321, and S1 = W2 * T4, where T4 is the thickness of the tail body 132, which is typically a uniform thickness. Depending on actual needs, T4 can be, for example, 0.15-0.35 mm. Within a reasonable minimum cross-sectional area S2 range, the tail body 132 can achieve a balance between battery safety and low internal resistance. When the minimum cross-sectional area S1 is too large, the tail body 132 cannot quickly fuse during thermal runaway, increasing safety risks. Conversely, when the minimum cross-sectional area S2 is too small, the fuse sensitivity is excessively high and the internal resistance is increased, seriously affecting the normal use of the battery. Of course, it is understandable that when calculating S1 and S2 above, the thickness of the tail body 132 at the fuse slot 1321 is the same as the thickness of the rest of the tail body 132, that is, the tail body 132 is of equal thickness, but this is not limited to this, and the thicknesses of the two can also be set to different.

[0150] like Figure 13As shown, the tail portion 132 includes a fifth side 1322 and a sixth side 1323 along its length, and a fourth side 1324 away from the disc portion 131. The ends of the fifth side 1322 are respectively connected to the fourth side 1324 and the first side 1311, while the ends of the sixth side 1323 are respectively connected to the fourth side 1324 and the second side 1313. The angle θ1 between the fifth side 1322 and the first side 1311 is 45-90 degrees, and the angle θ2 between the sixth side 1323 and the second side 1313 is 45-90 degrees. It is understood that if the angles θ1 and θ2 are too small, the bending of the tail portion 132 will cause excessive stress concentration at the angles θ1 and θ2, causing the disc portion 131 to deform or even fracture. If the angles θ1 and θ2 are too large, the disc portion 131 cannot ensure sufficient weldable area. In addition, the reasonable angle design of the angles θ1 and θ2 also helps the electrolyte to penetrate into the interior of the battery through the angles θ1 and θ2.

[0151] The tail body 132 will be further described below with reference to embodiments and comparative examples. The following embodiments and comparative examples of the present application are designed with reference to ordinary 21 series cylindrical lithium batteries.

[0152] Example 1:

[0153] Example 1 provides a cylindrical lithium battery, comprising a housing 110, a cap 120, a positive electrode current collector 130, a winding core 140, and a negative electrode current collector 150. The positive electrode current collector 130 includes a disk portion 131 and a tail portion 132, which are interconnected. The disk portion 131 is connected to the positive end of the winding core 140, and the tail portion 132 is connected to the cap 120. The tail portion 132 has a constant thickness along its length, and at least one pair of fuse slots 1321 is defined in the tail portion 132. The distance L5 between the center of the fuse slot 1321 and the end of the tail portion 132 away from the disk portion 131 is 72% of the length L4 of the tail portion 132. The minimum cross-sectional area S2 of the tail portion 132 at the fuse slot 1321 is 50% of the overall cross-sectional area S1 of the tail portion 132.

[0154] Comparative Example 1:

[0155] Comparative Example 1 provides a cylindrical lithium battery, which differs from Example 1 in that the minimum cross-sectional area S2 of the tail body 132 at the fuse slot 1321 is 20% of the overall cross-sectional area S1 of the tail body 132 .

[0156] Comparative Example 2:

[0157] Comparative Example 2 provides a cylindrical lithium battery, which differs from Example 1 in that the minimum cross-sectional area S2 of the tail body 132 at the fuse slot 1321 is 85% of the overall cross-sectional area S1 of the tail body 132 .

[0158] Comparative Example 3:

[0159] Comparative Example 3 provides a cylindrical lithium battery, which differs from Example 1 in that the distance L5 between the center of the fuse slot 1321 and the end of the tail portion 132 away from the disc portion 131 is 90% of the length L4 of the tail portion 132 .

[0160] Table 2 below evaluates the safety protection effectiveness of the positive electrode current collecting discs 130 fabricated in the aforementioned embodiments and comparative examples. The specific testing method is as follows: The sampled positive electrode current collecting disc 130 was secured to the fixture of a high-power programmable DC power supply. The test conditions were set as follows: voltage 20V, current 170A, power 150W, and delay time 10s. A temperature sensor was then turned on and aimed at the positive electrode current collecting disc 130. The recording function was activated, and the test was started on the instrument. The test ended when the fuse slot 1321 of the positive electrode current collecting disc 130 was observed to have blown. The time and current correlation curves obtained by the device, as well as the blown temperature reading from the temperature sensor, were recorded.

[0161] Table 2

[0162]

[0163]

[0164] Table 2 shows that when the distance L5 between the center of the fuse slot 1321 and the end of the tail body 132 away from the disc portion 131 is 72% of the length L4 of the tail body 132, and the minimum cross-sectional area S2 of the tail body 132 at the fuse slot 1321 is 50% of the overall cross-sectional area S1 of the tail body 132, the tripping temperature and the melting time of the fuse slot 1321 are relatively reasonable. When the ratio of the minimum cross-sectional area S2 of the tail body 132 at the fuse slot 1321 to the overall cross-sectional area S1 of the tail body 132 is too low, or when the ratio of the distance L5 between the center of the fuse slot 1321 and the end of the tail body 132 away from the disc portion 131 to the length L4 of the tail body 132 is too high, the fuse slot 1321 is relatively sensitive to temperature and will melt quickly. When the ratio of the minimum cross-sectional area S2 of the fuse slot 1321 to the entire cross-sectional area S1 of the tail portion 132 is too high, the fuse slot 1321 becomes less sensitive to temperature and cannot be quickly melted.

[0165] In some embodiments, the material of the positive electrode current collecting disk 130 is aluminum. On the one hand, aluminum has the characteristics of low internal resistance and good conductivity. On the other hand, the melting point of aluminum is relatively low. When the battery thermally runs away, the fuse slot 1312 can be melted to cut off the current.

[0166] The winding core 140 is described in detail below.

[0167] like Figure 1 、 Figure 14 and Figure 18 As shown, the winding core 140 is generally cylindrical, with a positive electrode flattening structure 141 and a negative electrode flattening structure 142 disposed on opposite sides of the winding core 140 along the axial direction. To facilitate smooth passage through the opening 114 into the inner cavity 113 of the outer shell 110, the diameter of the winding core 140 is slightly smaller than the inner diameter of the outer shell 110. It will be appreciated that after the winding core 140 is inserted into the outer shell, it is located within the area defined by the constricted neck 1121 and the bottom 111 of the outer shell 110, i.e., within the lower cavity 1132. Furthermore, the positive electrode flattening structure 141 is connected to the cap 120 via the positive current collecting disc 130, while the negative electrode flattening structure 142 is connected to the outer shell 110 via the negative current collecting disc 150.

[0168] like Figure 15 As shown, it can be understood that the core 140 is formed by stacking the first separator 143a, the positive electrode sheet 144a, the second separator 143b, and the negative electrode sheet 144b in sequence and then winding them. After winding, a core hole 145 is formed along the axial direction of the core 140 for injecting electrolyte. It can be understood that before forming the core 140, the positive electrode sheet 144a and the negative electrode sheet 142b need to be made. The positive electrode sheet 144a and the negative electrode sheet 144b each include a whole current collector substrate, such as aluminum foil or copper foil. In general, the current collector substrate is rectangular, with a length much greater than a width. The current collector substrate is divided into two regions along the width direction: one region is used for subsequent coating of electrode material, and the other region is used for subsequent die-cutting of tabs. The electrode material is first coated on the area where the electrode sheet is to be coated, and then multiple tabs are die-cut into the tab area to be spaced apart. The die-cutting method can be mechanical die-cutting or laser die-cutting. It is understandable that the structures of the positive electrode sheet 144a and the negative electrode sheet 144b are basically the same, and the difference lies in the different materials used for the current collector substrate and the different electrode materials coated in the material area.

[0169] It can be understood that after the stacking structure of the first diaphragm 143a, the positive electrode sheet 144a, the second diaphragm 143b and the negative electrode sheet 144b is completed, the full-electrode ear cut-and-stack structure located on the positive electrode sheet 144a and the negative electrode sheet 144b needs to be flattened to form a positive electrode flattening structure 141 and a negative electrode flattening structure 142 on opposite sides of the axial direction of the winding core 140, and the positive electrode flattening structure 141 and the negative electrode flattening structure 142 have flat cross-sections and are suitable for connection with the positive electrode collector 130 and the negative electrode collector 150.

[0170] It is understood that during the flattening process of the fully stacked tab structure, each tab is subjected to the flattening force, causing it to bend. During this process, the tabs may produce debris. Since the tabs themselves are made of conductive material, this debris falling into the battery may connect the positive and negative electrodes, causing an internal short circuit. In addition, if the positive and negative electrodes 144a and 144b are not designed properly, the high density of the flattened positive and negative structures 141 and 142 will result in a lack of effective space between them, which is not conducive to the infiltration of electrolyte, thereby affecting the battery's cycling performance.

[0171] The embodiments of the present application, through the rational design of the full-tab stacking structure in the positive electrode sheet 144a and the negative electrode sheet 144b, can effectively avoid the tab debris problem caused by the flattening process during the formation of the positive electrode flattening structure 141 and the negative electrode flattening structure 142, and can also improve the electrolyte infiltration effect to a certain extent, thereby improving the cycle performance of the battery. It should be noted that because the structures of the positive electrode sheet 144a and the negative electrode sheet 144b are basically the same, the following description of the full-tab stacking structure does not specifically distinguish between the positive electrode flattening structure 141 and the negative electrode flattening structure 142. That is, the full-tab stacking structure described below is applicable to both the positive electrode flattening structure 141 and the negative electrode flattening structure 142.

[0172] refer to Figure 16 and Figure 17 The full-tab stacking structure includes a current collector substrate 144, which includes a material area 1441 for coating polar materials and a tab area 1442. The material area 1441 and the tab area 1442 both extend along the length direction of the current collector substrate 144. At the location of the tab area 1442, the current collector substrate 144 has a plurality of tabs 1443 spaced apart along the length direction of the current collector substrate 144. The width of the edge (14431) of the tab 1443 facing the material area is W4, and the distance between the edges 14431 of two adjacent tabs 1443 facing the material area 1441 is W5.

[0173] Experimental testing has shown that setting the tab width W5 / W4 within a range of 20%-30% helps increase the tension of tab 1443 and prevents debris from being generated by the force applied during the flattening process. At the same time, if the width W4 of the tab facing the material area is too wide, wrinkles will form during the winding process. These wrinkles on tab 1443 will cause tab 1443 to be uneven after the subsequent flattening process, hindering the subsequent welding process. Specifically, if tab 1443 is uneven after flattening and then welded to the collector plate, the thickness of the concave areas will be thinner, which can easily lead to weld penetration. This unevenness also results in poor flatness of tab 1443 after flattening, making weld breakage more likely in the concave areas. Experimental testing has shown that setting the tab W5 / W4 ratio within the range of 20%-30% can reduce tab wrinkles during the winding process, reduce debris generated during tab flattening, and facilitate electrolyte infiltration. Furthermore, experimental testing has shown that controlling the W5 / W4 ratio within the range of 20%-30% can also improve the self-discharge rate K. A smaller K value reflects better battery performance to a certain extent. The applicant tested K values ​​for different W5 / W4 ratios, as shown in Table 3 below.

[0174] Table 3

[0175] Number of cell tests Tab W5 / W4 ratio K value mean 20 10％ 0.042 20 20％ 0.038 20 28％ 0.032 20 30％ 0.036 20 40％ 0.041 20 50％ 0.052 20 60％ 0.067

[0176] As can be seen from the table, controlling the W5 / W4 ratio within the range of 20%-30% can greatly improve its self-discharge rate K, and can effectively control the average value of its self-discharge rate K to be within 0.040, which has relatively better battery performance.

[0177] In some embodiments, the width W4 of the edge of the tab facing the material area is 0.5-3.0 mm, preferably 1.0-2.5 mm, and more preferably 1.5-2.2 mm. The applicant has found through testing that a width W4 of the edge of the tab facing the material area of ​​1.5-2.2 mm can balance the generation of debris during flattening, reduce wrinkles, and reduce the self-discharge rate. Specifically, the width W4 of the edge of the tab facing the material area can be 1.7 mm, 1.8 mm, or 1.9 mm, without specific limitation.

[0178] In some embodiments, the distance W5 between the edges 14431 of two adjacent tabs 1443 facing the material area is 0.2-0.6 mm. When flattening, the tabs 1443 are bent in sequence from the beginning c of the winding to the end d, so that the last bent tab overlaps the previous tab, as shown in FIG. Figure 19As shown, an overlapping area f and a gap area g will be formed between two adjacent tabs 1443. If the gap area g is too large, the internal resistance of the tab will be increased and the current overcurrent effect will be reduced. If the gap area g is reduced as much as possible, the distance W5 between the edges of the two adjacent tabs facing the material area must be as small as possible, but this will increase the difficulty of die-cutting and cause a decrease in the yield rate. After testing, the distance W5 between the edges of the two adjacent tabs facing the material area is controlled to 0.2-0.6mm, which can balance the die-cutting difficulty and the overcurrent effect. In some embodiments, W5 is preferably 0.3-0.5mm. In some embodiments, the distance W5 between the edges of the two adjacent tabs facing the material area is further preferably 0.3mm, 0.4mm, 0.5mm, etc.

[0179] In some embodiments, the current collector substrate 144 further includes a connection area 1444, which is located between the plurality of tabs 1443 and the material area 1441, that is, on the current collector substrate 144, there are a plurality of tabs 1443, connection areas 1444 and material areas 1441 arranged in sequence along the width direction of the current collector substrate 144. Figure 17 In the figure, the area between the dotted lines ab is the connection area 1444, the area above the dotted line a is the multiple tabs 1443, and the area below the dotted line is the material area 1441. During the flattening process, if the tab 1443 is directly connected to the material area 1441, when the tab 1443 is subjected to the flattening force, it is easy for the material area 1441 connected to the tab 1443 to be subjected to force. In this way, the wound material area 1441 may protrude outward, which will affect the subsequent assembly of the core 140 into the battery case. Therefore, the purpose of setting the connection area 1444 is to achieve a certain buffer. When flattening, the connection area 1444 bends inward, thereby avoiding the problem of the material area 1441 protruding outward.

[0180] In some embodiments, the distance between the edge 14431 where the tab 1443 connects to the connection area 1444 and the material area 1441 is H7. The tab 1443 is shaped like a parallelogram. The distance between the edge 14433 of the tab 1443 away from the material area 1441 and the material area 1441 is H6. The range of H7 / H6 is 10%-20%. The H7 area is the pre-bending area before the battery is wound. If bending at the connection between the tab and the material area will damage the material area and affect the coating, so a certain spacing is provided to facilitate bending. If the H7 / H6 ratio is too small, for example, if the H7 spacing is too small, the electrode material area will be bent, affecting the battery coating effect and easily causing a short circuit. For example, if the H6 spacing is too large, the tab is too high, and the tab intercalation during the cutting and stacking process occurs. Tab intercalation refers to the overlapping phenomenon of two adjacent tabs after being flattened, which affects the performance of the battery. If the H7 / H6 ratio is too large, for example, if the H7 spacing is too high, the effective tab height is short, affecting welding and current flow. Alternatively, if the H6 spacing is too small, the H6 height is too low, resulting in a low number of stacked layers and poor welding performance. In some embodiments, the H7 / H6 ratio is 13%, 15%, 17%, 19%, etc., without limitation.

[0181] like Figure 16 and Figure 17 As shown, 14433 and 14431 are two parallel sides of the parallelogram, and 14432 is the side connecting 14433 and 14431. It is well known to those skilled in the art that the dotted line 14431 is for reference only and is not present in the actual product. As previously mentioned, the tab 1443 is die-cut from the current collector substrate 144, wherein the tab 1443 includes an edge 14431 connected to the current collector substrate, two edges 14432 connected to the leading end and the trailing end of the edge, respectively, which are generated by die-cutting part of the electrode material of the current collector substrate, and an edge 14433 opposite the edge 14431 connected to the current collector substrate 144. The four edges are connected to form a parallelogram.

[0182] In some embodiments, the distance H7 between the edge 14431 where the tab 1443 connects to the connection area 1444 and the material area 1441 is 0.4-0.6 mm. If the distance H7 between the edge 14431 where the tab 1443 connects to the connection area and the material area is too high, the height of the tab 1443 will be reduced, thereby affecting the subsequent welding effect and the flow effect. During the battery manufacturing process, the height and diameter of the battery are generally fixed according to industry standards, so the length, width and thickness of the current collector substrate 144 are basically fixed. A connection area 1443 is reserved for bending in the tab area 1442 of the current collector substrate 144. At this time, in order to maximize the capacity of the battery, the width of the material area 1441 remains unchanged, and the width of the tab 1443 can only be reduced. If the width of the connection area 1444 is too wide, the width of the tab 1443 will be too narrow. If the tab 1443 is too narrow, it will affect the welding effect. After flattening, the outer tab 1443 will overlap on top of the inner tab 1443. If the tab 1443 is too narrow, some areas will appear very thin due to the small number of overlapping tabs 1443, which may easily cause penetration in subsequent welding; secondly, it will affect the overcurrent effect of the current. If the tab 1443 is too short, the entire tab area will become thinner, the internal resistance will increase, and the overcurrent current will decrease. After testing, the distance H7 between the edge where the tab connects to the connection area and the material area is 0.4-0.6mm, which can easily balance the problem of the material area protruding outward and the welding effect and current overcurrent effect.

[0183] In some embodiments, the angle β between the edge 14432 of the tab facing the material region and the width direction of the current collector substrate 144 is 14-18°.

[0184] The purpose of beveling is to make the tabs lean to one side after flattening. Although there is a gap between the tabs after cutting, the tabs can still fit as close as possible after flattening, increasing the density of the tabs after flattening. After flattening, two adjacent tabs 1443 will form an overlapping area f and a gap area g. If the angle is too small, such as a rectangular structure, there will be an excessively large gap area g between the tabs, which will make the overall density of the tabs too low and easy to weld through later, thus affecting welding performance. In addition, if the angle is too small, due to excessive stress on the tabs, it is still easy to generate particle debris during the subsequent flattening process, posing a short circuit risk and affecting battery safety performance. If the angle is too large, the area of ​​the tab gap area g will also be too large, thereby reducing the overall density of the tabs, thereby affecting subsequent welding performance. In addition, a large angle will cause the stress between the tabs to be too small, which will easily cause wrinkles and cracks in the wound electrode sheet, ultimately affecting the overall safety and cycle performance of the battery. Therefore, the present invention sets the angle β in the range of 14-18°. This ensures that the tabs have sufficient electrolyte infiltration while maintaining a suitable density after flattening, while also taking into account the welding performance of the tabs, thereby achieving sufficient safety and cycle performance. The applicant tested the area values ​​of the gap region g at different angles β, as shown in Table 4 below. In some embodiments, the angle β is set to 14°, 16°, 18°, etc.

[0185] Table 4

[0186]

[0187]

[0188] In some embodiments, as Figure 15 As shown, the core 140 is formed by stacking the first diaphragm 143a, the positive electrode sheet 144a, the second diaphragm 143b and the negative electrode sheet 144b in sequence and then winding them. The starting end of the winding is called the head end c, and the end at the outermost layer after winding is called the end d. After the winding is completed, the first diaphragm 143a is located at the innermost side of the core 140.

[0189] like Figure 15 As shown, in some embodiments, the length of the multiple tabs 1443 in the tab area 1442 along the length direction of the current collector substrate 144 is less than the length L7 of the material area 1441, and the end of the material area 1441 facing the tab area 1442 along the length direction of the current collector substrate 144 is not connected to the connection area 1444, and the end not connected to the connection area 1444 is called the first cut-off area 1445, wherein the end not connected to the connection area 1444 can be located at either the head end c or the end end d.

[0190] In some embodiments, the first cutout region 1445 of the current collector substrate 144 is located at the head end c. That is, the head end c of the current collector substrate 144 is die-cut during die-cutting so that the head end c does not have a tab. If the head end c has a tab, the tab at the head end c can easily clog the winding core hole 145 after winding and flattening, hindering the subsequent injection of electrolyte.

[0191] In some embodiments, the length of first cutout region 1445 is L8, and the ratio L8 / L7 is 5%-15%. If L8 / L7 is too small, the winding hole 145 may become clogged. If L8 / L7 is too large, the diaphragm may be exposed, allowing metal debris to enter the electrolyte and potentially cause a short circuit. Keeping L8 / L7 between 5% and 15% reduces both clogs in the winding hole 145 and the probability of a short circuit. In some embodiments, L8 / L7 is 7%, 9%, 11%, 13%, etc., without limitation.

[0192] In some embodiments, the length L8 of the first cut-away area 1445 is 105-130 mm. Further, L8 is preferably 144 mm, 115 mm, 120 mm, 125 mm, etc., without limitation.

[0193] In some embodiments, the end of the material region 1441 along the length of the current collector substrate 144 that faces the tab region 1442 is not connected to the connection region 1444. This end is referred to as a second cutout region 1446. The second cutout region 1446 can be located at either the head end c or the end end d. In some embodiments, the second cutout region 1446 is located at the end end d. If a tab exists at the end d, the tab may protrude outward during the flattening process, hindering the subsequent assembly of the winding core 140 into the shell.

[0194] In some embodiments, the length of the second cutout region 1446 is L9, and the ratio L9 / L7 is 10%-20%. If L9 / L7 is too small, the core 140 may easily bend over, causing it to protrude from the diaphragm, hindering insertion into the battery case. If L9 / L7 is too long, the diaphragm may be easily exposed, allowing metal debris to enter the electrolyte and potentially causing a short circuit. Controlling L9 / L7 to 10%-20% facilitates insertion of the core 140 into the battery case while reducing the probability of a short circuit. In some embodiments, L9 / L7 is 13%, 15%, 18%, etc., without limitation.

[0195] In some embodiments, the length L9 of the second cut-away area 1446 is 175-205 mm. Further, L9 is preferably 185 mm, 195 mm, etc., without limitation.

[0196] In some embodiments, one end of the tab region 1442 has a first cutout region 1445, and the other end has a second cutout region 1446. The length of the first cutout region 1445 along the length of the current collector substrate 144 is L8, and the ratio of L8 to L7 is in the range of 5%-15%. The length of the second cutout region 1446 along the length of the current collector substrate 144 is L9, and the ratio of L9 to L7 is in the range of 10%-20%. In some embodiments, the first cutout region 1445 and the second cutout region 1446 are flush with each other in the width direction.

[0197] The negative electrode current collecting disk 150 is described in detail below.

[0198] like Figure 1 and Figure 20 As shown, the negative electrode current collecting disc 150 is circular as a whole. Along the thickness direction, the negative electrode current collecting disc 150 has a first side 151 and a second side 152 that are opposite to each other. Since the second side 152 is provided with a raised platform 1521 described below, it is necessary to distinguish the directions when welding the negative electrode current collecting disc 150 to the outer shell 110 and the winding core 140. Specifically, the second side 152 is welded to the shell bottom 111 through the raised platform 1521, and the first side 151 is welded to the negative end of the winding core 140. In this way, a welding connection is achieved between the winding core 140, the negative electrode current collecting disc 150 and the outer shell 110, and a passage is formed between the three. That is, the negative electrode current collecting disc 150 indirectly connects the winding core 140 to the outer shell 110.

[0199] To ensure that the raised platform 1521 fits well with the surface of the outer shell 110, in this embodiment, the negative electrode current collecting plate 150 is provided with a raised platform 1521 with a flat surface on the second side 152. The surface of the raised platform 1521 is higher than the surface of the second side 152, and the surface area of ​​the raised platform 1521 is smaller than the surface area of ​​the second side 152. The surface of the raised platform 1521 is suitable for abutting against the inner surface of the shell bottom 111, and the flatness of the surface of the raised platform 1521 is 0.01-0.05mm. It is understood that because the surface of the raised platform 1521 is higher than the surface of the second side 152, that is, the surface of the raised platform 1521 serves as the top surface of the second side 152, after the negative electrode current collecting plate 150 is assembled into the outer shell 110, the surface of the raised platform 1521 will abut the inner surface of the shell bottom 111. In other words, the surface of the raised platform 1521 and the inner surface of the shell bottom 111 are closely attached to each other, forming a surface-to-surface contact connection between the two. Subsequently, the area where the raised platform 1521 overlaps with the shell bottom 111 can be laser-welded through the outer surface 1112 of the bottom plate, thereby welding the raised platform 1521 to the outer shell 110. It is also understood that if the flatness of the raised platform 1521 is too large, its contact with the inner surface of the shell bottom 111 will be poor, thereby affecting the welding quality. Conversely, if the flatness of the raised platform 1521 is too small, it will be difficult to process and the cost will be too high.

[0200] In this embodiment, since the ratio of the diameter D8 of the negative electrode current collecting disc 150 to the diameter D6 of the winding core 140 is set at 90%-98%, the weldable area between the negative electrode current collecting disc 150 and the winding core 140 can be effectively increased, and the welding processability is good. At the same time, a smaller raised platform 1521 is provided on the second side 152 of the negative electrode current collecting disc 150. Since the raised platform 1521 has a smaller area, it can ensure good surface flatness during the processing, so that the surface of the raised platform 1521 can better fit the inner surface of the shell bottom 111, and can effectively avoid welding quality problems such as cold welding between the two. The battery using the negative electrode current collecting disc 150 has better performance and yield rate.

[0201] For the purpose of facilitating processing and reducing costs, in some embodiments, the raised platform 1521 is formed by the negative electrode current collecting disc 150 through a stamping process, that is, the raised platform 1521 is integrally formed with the negative electrode current collecting disc 150. Therefore, through a reasonable stamping die design, the negative electrode current collecting disc 150 of this embodiment can be efficiently processed, and the negative electrode current collecting disc 150 and the raised platform 1521 have high dimensional accuracy and good surface quality, which facilitates welding with the winding core 140 and the housing 110. Of course, this is not limited to this, and the raised platform 1521 can also be formed in other ways. For example, the raised platform 1521 can be a sheet metal component with excellent welding and conductive properties. The metal component can be bonded to the surface of the second side 152 of the negative electrode current collecting disc 150 by pressing, thereby forming the raised platform 1521.

[0202] In some embodiments, the raised platform 1521 is formed in the central area of ​​the second side 152. Thus, after the negative electrode current collecting plate 150 is assembled into the outer shell 110, the raised platform 1521 can be aligned with the central area of ​​the shell bottom 111, making it convenient to weld the outer shell 110 and the raised platform 1521 using welding equipment.

[0203] Furthermore, the raised platform 1521 is circular in shape. Thus, the raised platform 1521 can be co-centered with the negative electrode current collecting plate 150, facilitating stamping using a stamping die. Of course, the shape of the raised platform 1521 is not limited to a circle. For example, the raised platform 1521 can also be square, triangular, or other shapes.

[0204] like Figure 20 and Figure 21As shown, it can be understood that a raised platform 1521 is punched out on the second side 152 of the negative electrode current collecting disc 150 through a stamping process, and accordingly, a recessed portion 1511 is formed on the first side 151 at a position corresponding to the raised platform 1521. To facilitate welding of the negative electrode current collecting disc 150 and the winding core 140, in some embodiments, the first side 151 has an annular welding area 1512 surrounding the recessed portion 1511. The surface of the welding area 1512 is suitable for abutting the negative end of the winding core 140. For example, the welding area 1512 is also configured to have a flat surface so that the two surfaces can closely fit each other, thereby improving welding quality.

[0205] like Figure 21 As shown, in some embodiments, the diameter D9 of the raised platform 1521 is 28%-38% of the diameter D8 of the negative electrode current collecting disc 150, that is, D9 / D8 = 28%-38%. As previously mentioned, the diameter D8 of the negative electrode current collecting disc 150 is substantially consistent with the diameter of the winding core 140. If the diameter of the raised platform 1521 is too large, its surface flatness will be reduced, and its adhesion to the inner surface of the shell bottom 111 will be poor, thereby affecting the welding quality. Conversely, if the diameter of the raised platform 1521 is too small, the weldable area of ​​the raised platform 1521 will be small, and it will be easy to desolder during welding, which will increase the difficulty of subsequent welding process and increase costs.

[0206] Further, if Figure 22 As shown, in some embodiments, the height difference between the surface of the raised platform 1521 and the surface of the second side 152 is H8, which is 18%-30% of the thickness T5 of the negative electrode current collecting disc 150, that is, H8 / T5 = 18%-30%. It is understood that if the raised platform 1521 is set too high, that is, H8 / T5 is too large, the winding core 140 will squeeze and deform the periphery of the negative electrode current collecting disc 150 during assembly, and additional longitudinal space will be occupied. Conversely, if the raised platform 1521 is set too low, that is, H8 / T5 is too small, the raised platform 1521 will be difficult to process, for example, it will be difficult to form the raised platform 1521 through a stamping process.

[0207] In some embodiments, the negative electrode current collecting disc 150 is made of copper and is plated with nickel. Compared to negative electrode current collecting discs 150 made of copper-nickel alloy, copper as the base material has a significantly lower internal resistance. Furthermore, the nickel plating on the surface of the negative electrode current collecting disc 150 effectively improves the corrosion resistance of the negative electrode current collecting disc 150.

[0208] Furthermore, the thickness of the nickel layer is set to 0.08-1.5 μm, more preferably 0.9-1.1 μm. It is understood that if the nickel layer is too thin, it will not be able to provide anti-oxidation protection. Conversely, if the nickel layer is too thick, it will increase the difficulty and cost of the nickel plating process. On the other hand, it will increase the hardness of the negative electrode current collecting disc 150, resulting in a decrease in the plasticity of the negative electrode current collecting disc 150, and will also increase the internal resistance, resulting in reduced battery performance.

[0209] Throughout this specification, reference to terms such as "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 that embodiment or example are included in at least one embodiment or example of the present embodiment. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0210] 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 these embodiments without departing from the principles and intent of the present embodiment, and the scope of the present embodiment is defined by the claims and their equivalents.

Claims

1. A cylindrical lithium battery, characterized in that: The device comprises a housing (110), a cap (120), a positive electrode current collecting disc (130), a winding core (140) and a negative electrode current collecting disc (150), wherein: The shell (110) comprises a shell bottom (111) and a side wall (112), the top end of the side wall (112) has an opening (114), the side wall (112) is concave inwardly along the circumferential direction at a position near the opening (114) to form a necking portion (1121), the outer surface of the side wall (112) forms a necking groove (1123) at the necking portion (1121), the winding core (140) is located in the area defined by the necking portion (1121) and the shell bottom (111) in the shell (110), the height H2 of the necking groove (1123) is 0.1%-1% of the height H1 of the shell (110), and the depth H3 of the necking groove (1123) in the radial direction is 5%-10% of the outer diameter D1 of the shell (110); The positive electrode current collecting disc (130) comprises a disc body (131) and a tail body (132) connected to each other, wherein the disc body (131) is connected to the positive end of the winding core (140), and the tail body (132) is connected to the cap (120). A circular first hole (1315) is provided at the center of the disc body (131), and at least one circular second hole (1316) is provided around the periphery of the first hole (1315). All the second holes (1316) are The sum of the areas is 0.9-1.5 times the area of ​​the first hole (1315); at least one fuse slot (1321) is provided on the tail body (132); at positions other than the fuse slot (1321) on the tail body (132), the tail body (132) has an overall cross-sectional area S1; the tail body (132) has a minimum cross-sectional area S2 at the position of the fuse slot (1321); the minimum cross-sectional area S2 is 45%-65% of the overall cross-sectional area S1.

2. The cylindrical lithium battery according to claim 1, characterized in that The winding core (140) has a winding core hole (145) extending therethrough, and the diameter D4 of the first hole (1315) is 1.4-1.8 times the diameter D7 of the winding core hole (145); the negative electrode current collecting disk (150) has a first side (151) and a second side (152) opposite to each other, the first side (151) being connected to the negative end of the winding core (140), and a flat raised platform (1521) being provided at the center of the second side (152), the raised platform (1521) being connected to the inner surface of the shell bottom (111), and the flatness of the surface of the raised platform (1521) is 0.01-0.05 mm.

3. The cylindrical lithium battery according to claim 2, characterized in that: The diameter D3 of the disk body (131) is 80%-95% of the diameter D6 of the winding core (140); the diameter D8 of the negative electrode current collecting disk (150) is 90%-98% of the diameter D6 of the winding core (140); the raised platform (1521) is circular and located at the center of the second side (152); the diameter D9 of the raised platform (1521) is 28%-38% of the diameter D8 of the negative electrode current collecting disk (150).

4. The cylindrical lithium battery according to claim 2, characterized in that: The diameter D5 of the second hole (1316) is 50%-70% of the diameter D4 of the first hole (1315); the height difference H8 between the surface of the raised platform (1521) and the surface of the first side (151) is 18%-30% of the thickness T5 of the negative electrode current collecting disk (150).

5. The cylindrical lithium battery according to any one of claims 2 to 4, characterized in that: The shape of the disk body (131) is a closed axisymmetric figure consisting of a first side (1311), an arc (1312), a second side (1313) and a third side (1314) connected end to end in sequence. The shape of the tail body (132) is a closed axisymmetric figure consisting of a third side (1314), a fifth side (1322) extending along the length direction of the tail, a fourth side (1324) away from the disk body and a sixth side (1323) extending along the length direction of the tail, wherein the two ends of the fifth side (1322) are respectively connected to the fourth side (1324). ) is connected to the first side (1311), and the two ends of the sixth side (1323) are respectively connected to the fourth side (1324) and the second side (1313); the raised platform (1521) is formed by integral stamping of the negative electrode current collecting disc (150), and the first side (151) forms a recessed portion (1511) at a position corresponding to the raised platform (1521), and a welding area (1512) is formed around the recessed portion (1511), and the surface of the welding area (1512) abuts against the negative end of the winding core (140).

6. The cylindrical lithium battery according to claim 5, characterized in that: The length L4 of the tail body (132) is 85%-95% of the diameter D3 of the disk body (131); the distance L5 between the center position of the fuse slot (1321) and the end of the tail body (132) away from the disk body (131) is 68%-78% of the length L4 of the tail body (132).

7. The cylindrical lithium battery according to claim 5, characterized in that: The disc body portion (131) has a center angle A, and 40°≤∠A≤60°, wherein the center angle A has the center of the circle corresponding to the arc (1312) as its vertex, and two sides respectively pass through the end point of the first side (1311) away from the arc (1312) and the end point of the second side (1313) away from the arc (1312); the first width W2 of the tail body portion (132) is W2=D3*sin(∠B / 2), and 20°≤∠B≤40°, wherein ∠B has the center of the circle corresponding to the arc (1312) as its vertex, and two sides respectively pass through the intersection of the fifth side (1322) and the sixth side (1323) with the full circle where the arc (1312) is located.

8. The cylindrical lithium battery according to claim 7, characterized in that: The second width W3 of the tail body (132) at the fuse slot (1321) is 3 / 8-3 / 4 of the first width W2; the dimension L6 of the fuse slot (1321) along the length direction of the tail body (132) is in the range of 0<L6≤W2.

9. The cylindrical lithium battery according to claim 5, characterized in that: The included angle θ1 between the fifth side (1322) and the first side (1311) is 45-90°, and the included angle θ2 between the sixth side (1323) and the second side (1313) is 45-90°.

10. The cylindrical lithium battery according to any one of claims 1 to 4, characterized in that: The neck portion (1121) includes a first wall portion (1121a) and a second wall portion (1121b) extending toward the center of the housing (110), and the neck portion (1121) also includes a connecting portion (1121c) for connecting the first wall portion (1121a) and the second wall portion (1121b). The outer surfaces of the first wall portion (1121a), the second wall portion (1121b) and the connecting portion (1121c) jointly define a necking groove (1123), and the first wall portion (1121a) and the second wall portion (1121b) are connected to each other. 1b) are arranged at a certain inclination angle with the shell bottom (111); the cover cap (120) includes a stacked explosion-proof valve plate (122) and a terminal plate (124); the tail body (132) is connected to the bottom of the terminal plate (124); the explosion-proof valve plate (122) is provided with a first notch (1221a) and a second notch (1221b); the first notch (1221a) is a closed circle connected at its head and tail ends; the second notch (1221b) is a line segment; the first notch (1221a) and the second notch (1221b) intersect.

11. The cylindrical lithium battery according to claim 10, characterized in that: The larger of the angles between the first wall portion (1121a) and the shell bottom (111) and the angle between the second wall portion (1121b) and the shell bottom (111) is α, and the range of α is α<10°; the explosion-proof valve disc (122) is provided with a thinning portion (1222) extending in the radial direction, the first notch (1221a) is arranged within the radial range where the thinning portion (1222) is located, the thickness of the thinning portion (1222) is T3, the depth of the first notch (1221a) is H4, and the range of H4 / T3 is 30%-60%.

12. The cylindrical lithium battery according to claim 11, characterized in that: The range of α is 1-5°; the width of the thinning portion (1222) is W1, and the range of W1 is 3-8 mm.

13. The cylindrical lithium battery according to claim 10, characterized in that: The minimum wall thickness of the neck portion (1121) is T2, the wall thickness of the side wall (112) is T1, and the range of T2 / T1 is more than 80%; the diameter D2 of the first notch (1221a) is equal to the length L2 of the second notch (1221b).

14. The cylindrical lithium battery according to claim 13, characterized in that: The range of T2 is 0.1-0.2mm; the bottoms of the first notch (1221a) and the second notch (1221b) are provided with chamfered portions, and the radii of the chamfered portions are the same, and the radius of the chamfered portions is R, and the range of R is 0.05-.15mm.

15. The cylindrical lithium battery according to claim 10, characterized in that: The distance L1 between the lowest point of the neck portion (1121) and the upper surface of the shell bottom (111) is 90%-98% of the height H1 of the shell (110); the depth H4 of the first notch (1221a) is less than the depth H5 of the second notch (1221b), and the depth of the middle part of the second notch (1221b) is greater than the depths at both ends.

16. The cylindrical lithium battery according to any one of claims 1 to 4, characterized in that: The winding core (140) has a relative positive electrode flattening structure (141) and a negative electrode flattening structure (142), and the positive electrode flattening structure (141) and the negative electrode flattening structure (142) are both formed by flattening a full-electrode tab stacking structure, and the full-electrode tab stacking structure includes a current collector substrate (144), and the current collector substrate (144) is divided into a material area (1441) for coating polar materials and a tab area (1442) along the width direction, and the material area (1441) and the tab area (1442) extend along the length direction of the current collector substrate (144), and the current collector substrate (144) has a There are multiple pole tabs (1443) spaced apart along the length direction, the width of the edge (14431) of the pole tab (1443) facing the material area (1441) is W4, the distance between the edges (14431) of two adjacent pole tabs (1443) facing the material area (1441) is W5, the range of W5 / W4 is 20%-30%, and the shape of the pole tab (1443) is a parallelogram, and the angle β between the edge (14432) connected to the edge (14431) of the pole tab (1443) facing the material area (1441) and the width direction of the current collector substrate (144) is 14-18°.

17. The cylindrical lithium battery according to claim 16, characterized in that: A connection area (1444) is further provided between the material area (1441) and the tab area (1442); the distance between the edge (14431) where the tab (1443) is connected to the connection area (1444) and the material area (1441) is H7; the length between the edge (14433) of the tab (1443) away from the material area (1441) and the material area (1441) is H6; and the range of H7 / H6 is 10%-20%.

18. The cylindrical lithium battery according to claim 17, characterized in that: The range of H7 is 0.4-0.6 mm, and the range of W4 is 1.5-2.2 mm.

19. The cylindrical lithium battery according to claim 16, characterized in that: The length of the multiple tabs (1443) of the tab area (1442) along the length direction of the current collector substrate (144) is less than the length L7 of the material area (1441), and one end of the two ends of the tab area (1442) has a first cut-out area (1445), and the other end has a second cut-out area (1446). The length of the first cut-out area (1445) along the length direction of the current collector substrate (144) is L8, and the range of L8 / L7 is 5%-15%. The length of the second cut-out area (1446) along the length direction of the current collector substrate (144) is L9, and the range of L9 / L7 is 10%-20%.

20. The cylindrical lithium battery according to claim 19, characterized in that: The range of L8 is 105-130 mm, and the range of L9 is 175-205 mm.

Images