Cylindrical lithium battery

Abstract

The utility model provides a cylindrical lithium battery. An anti-explosion valve plate in the cylindrical lithium battery is provided with a first nick and second nicks, the first nick is a closed circle with the head end and the tail end connected, the second nicks are in a line segment shape, the first nick and the second nicks intersect, a positive collector plate is provided with first holes and second holes, the sum of the areas of all the second holes is 0.9-1.5 times of the area of the first hole, and the sum of the areas of all the second holes is 0.9-1.5 times of the area of the first hole. The diameter D3 of the first hole is 1.4-1.8 times of the diameter D6 of the roll core hole; the negative collector plate is provided with a heightening platform which is connected with the shell bottom and has a flat surface, and the planeness of the surface of the heightening platform is 0.01-0.05 mm. According to the cylindrical lithium battery, the explosion-proof valve plate can be timely and effectively opened, so that the cylindrical lithium battery has the characteristic of relatively high safety, and in addition, the welding effects of the positive current collecting plate, the negative current collecting plate, the roll core and the shell are good.

Description

Technical Field

[0001] This application relates to the technical field of lithium-ion batteries, and particularly to a cylindrical lithium battery. Background Art

[0002] In related technologies, cylindrical batteries are usually encapsulated with cylindrical steel shells. The bare battery core is made by a winding process to form a cylindrical winding core. The cap is located at the top of the battery and is connected to the positive electrode in the winding core through a positive current collector plate. The steel shell is connected to the negative electrode in the winding core through a negative current collector plate. The positive current collector plate and the negative current collector plate enable electrons to be transmitted longitudinally from the current collector to the current collector plate, 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] In addition, the existing positive current collector plate for cylindrical lithium batteries consists of a plate body and a tail body. The plate body is used to connect with the winding core electrode group, and the tail body is bent and connected to the cap after being bent. The presence of the plate body will hinder the electrolyte penetration efficiency. Generally, holes can be opened on the outer periphery of the plate body to improve the electrolyte penetration effect. However, the holes on the outer periphery may be blocked by encapsulation, resulting in limited improvement effect. In addition, if the opening ratio is too large, there will also be a lack of sufficient effective weldable areas on the plate body, affecting the welding effect. Therefore, how to ensure better electrolyte penetration effect of the positive current collector plate while also achieving better welding effect is an urgent problem to be solved currently.

[0004] Furthermore, for the negative current collector plate, it needs to be welded to the winding core and the steel shell respectively. Therefore, in order to increase the welding area between the negative current collector plate and the steel shell and the winding core, and at the same time increase the current conduction area, generally, the diameter of the negative current collector plate can be considered to be increased. However, when the diameter of the negative current collector plate is large, the flatness of its surface will become poor. Therefore, it is difficult to ensure good fitting between the negative current collector plate and the metal shell. In the case of poor fitting between the two, there are risks such as poor welding after welding, which will further cause defects such as open circuit of the lithium battery and inability to work normally.

[0005] In addition, an explosion-proof valve piece is provided in the cap. The explosion-proof valve piece usually has an explosion-proof notch at the edge position. Its function is to tear when the gas pressure inside the battery reaches the limit value, so that the battery can relieve pressure, avoiding battery deformation, swelling, or even combustion or explosion. However, for cylindrical lithium batteries, the reasons and positions for the generation of internal gas are relatively complex. Therefore, the internal pressure distribution of the battery usually has no pattern. In some cases, the explosion-proof notch cannot respond and break immediately. Therefore, this kind of explosion-proof piece structure has certain safety hazards. Content of the Utility Model

[0006] An embodiment of the present application provides a cylindrical lithium battery to at least solve the technical problems that it is difficult to balance the welding performance and liquid injection performance of the positive and negative current collectors in the existing cylindrical lithium batteries, and the insufficient safety.

[0007] An embodiment of the first aspect of the present application provides a cylindrical lithium battery, including a housing with a bottom, a cap, a positive current collector, a winding core with a winding core hole, and a negative current collector. The positive end of the winding core is connected to the cap through the positive current collector, and the negative end of the winding core is connected to the bottom of the housing through the negative current collector, wherein:

[0008] At least one of the positive end and the negative end is formed by flattening a full tab;

[0009] The cap is arranged on the top of the housing and includes an explosion-proof valve sheet and a terminal plate stacked. The explosion-proof valve sheet is provided with a first notch and a second notch. The first notch is a closed circle with the head and tail connected, and the second notch is in a line shape. The first notch intersects with the second notch;

[0010] The positive current collector includes a disk body part and a tail body part connected to each other. The disk body part is connected to the positive end, and the tail body part is connected to the terminal plate. A circular first hole is provided at the center of the disk body part, and at least one circular second hole is arranged around 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 diameter D3 of the first hole is 1.4-1.8 times the diameter D6 of the winding core hole;

[0011] The negative current collector has opposite first and second sides. The first side is connected to the negative end, and a flat elevation platform is provided on the second side. The elevation platform is connected to the inner surface of the bottom of the housing, and the flatness of the surface of the elevation platform is 0.01-0.05 mm.

[0012] The cylindrical lithium battery according to the embodiment of the present application has at least the following beneficial effects:

[0013] By reasonably designing the sizes of the first hole and the second hole for the electrolyte to penetrate through on the positive current collector, the balance between the liquid injection efficiency and the weldable area can be achieved, and the welding safety can be ensured at the same time. And, by providing a flat elevation platform on the side where the negative current collector is connected to the inner surface of the bottom of the housing, due to the small area of the elevation platform, good surface flatness can be ensured, and the surface of the elevation platform can be well attached to the inner surface of the bottom of the housing, which can reduce the risk of welding quality problems such as virtual welding between the two.

[0014] In addition, by providing a first notch and a second notch on the explosion-proof valve piece, when abnormal conditions such as overheating and short circuit occur inside the battery, resulting in a sharp rise in the internal air pressure, whether the air pressure value in the edge area or the middle area reaches the preset value first, one of the first notch and the second notch will break first, so that the battery can relieve pressure in time. Moreover, since the first notch intersects with the second notch, when one of the first notch or the second notch breaks, it will also drive the other to break, thereby expanding the opening area of the explosion-proof valve piece and improving the pressure relief effect. Thus, when the gas pressure inside the battery exceeds the preset value, the explosion-proof valve piece can quickly and effectively open to release the pressure, thereby enhancing the safety of the battery.

[0015] In a possible implementation manner, the explosion-proof valve piece 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 T1, and the depth of the first notch is H1, satisfying: H1 / T1 = 30% - 60%; the shape of the disc body portion is a closed axisymmetric figure formed by sequentially connecting a first side, an arc, a second side, and a third side end to end, and both the first side and the second side are connected to the tail body portion. At the same time, the shape of the disc body portion facilitates its welding with the winding core.

[0016] By reasonably setting the thickness of the thinning portion and the depth of the first notch, it can effectively make the notch assembly break when the opening condition is met to relieve the pressure of the battery, and at the same time ensure that the explosion-proof valve piece has sufficient strength and rigidity, which is convenient for processing and assembly.

[0017] In a possible implementation manner, the diameter D1 of the first notch is equal to the length L1 of the second notch; the tail body portion includes a fifth side and a sixth side along the length direction of the tail body portion and a fourth side away from the disc body portion, both ends of the fifth side are respectively connected to the fourth side and the first side, both ends of the sixth side are respectively connected to the fourth side and the second side, 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°.

[0018] By setting the diameter of the first notch to be equal to the length of the second notch, the second notch divides the first notch into two symmetrical parts, which is convenient for processing. And after the explosion-proof valve piece is assembled to the cylindrical lithium battery, the second notch is located in the central area of the cylindrical lithium battery, so that the explosion-proof valve piece can be smoothly opened to relieve pressure. At the same time, the reasonable angle range between the fifth side and the first side, and the sixth side and the second side helps to balance the mechanical properties of the positive current collector plate and the area size of the weldable area of the disc body portion.

[0019] In a possible implementation, the depth H1 of the first notch is less than the depth H2 of the second notch, and the depth of the middle of the second notch is greater than the depth of both ends; the tail body is provided with a weakened portion, and the cross-sectional area of the weakened portion accounts for 45% to 65% of the cross-sectional area of the tail body.

[0020] By increasing the depth of the second notch, the effect of the increase in thickness of the explosion-proof valve sheet in the middle region on the second notch can be reduced, so as to ensure that the explosion-proof valve sheet opens smoothly at the second notch. In addition, by setting the depth of the second notch to be greater in the middle than at both ends, that is, the depth of the second notch is deeper in the middle and shallower at both ends, the effect of the step-wise change in thickness of the explosion-proof valve sheet in the middle region can be reduced, so as to ensure that the explosion-proof valve sheet opens smoothly at the second notch. At the same time, by reasonably designing the weakening portion and its cross-sectional area, the positive electrode current collector can achieve a balance between battery safety and low internal resistance.

[0021] In a possible embodiment, the positive terminal is formed by flattening the entire tab; the side of the disk body facing the positive terminal abuts against the flattened positive terminal, so that the diameter of the disk body is D2, and the diameter of the second hole is D4, satisfying: D3 / D2=25%-35%, D4 / D3=50%~70%.

[0022] By setting the positive terminal to be formed by flattening the entire pole ear, the positive terminal is densely stacked and has a flat cross section, avoiding wasting space in the longitudinal direction, and the utilization rate of the internal space of the shell is high, which can further improve the energy density of the battery. At the same time, the positive terminal has a good fit with the positive electrode collector after abutting, which is conducive to laser welding and can effectively reduce process defects such as cold welding. In addition, by reasonably designing the size of the first hole and the second hole of the positive electrode collector, the injection efficiency and the welding effect with the positive terminal can be balanced.

[0023] In a possible embodiment, the negative terminal is formed by flattening the entire electrode ear, the raised platform is formed by integral stamping of the negative electrode collector plate, a recess is formed at a position corresponding to the raised platform on the first side, a welding area is formed around the recess, and the surface of the welding area is in contact with the flattened negative terminal.

[0024] By setting the negative terminal to be formed by flattening the entire pole ear, the negative terminal is densely stacked and has a flat cross section, avoiding wasting space in the longitudinal direction, and the utilization rate of the internal space of the shell is high, which can further improve the energy density of the battery. At the same time, the negative terminal has a good fit after abutting against the negative electrode collector, which is conducive to laser welding and can effectively reduce process defects such as cold welding. In addition, the surface quality of the welding area set in the negative electrode collector is good, and the fit effect after abutting against the negative terminal is good, which is conducive to laser welding and can effectively reduce process defects such as cold welding.

[0025] In a possible implementation, the material of the positive current collector disk is aluminum, the material of the negative current collector disk is copper, and the surface of the negative current collector disk is plated with a nickel layer, and the thickness of the nickel layer is 0.08 - 1.5 μm.

[0026] The positive current collector disk made of aluminum and the negative current collector disk made of copper have the characteristics of low internal resistance and good electrical conductivity. And during thermal runaway, the positive current collector disk is prone to fuse to cut off the current, while the surface of the negative current collector disk is plated with a nickel layer, which can effectively improve the corrosion resistance of the negative current collector disk.

[0027] In a possible implementation, the diameter of the disk body part is D2, the diameter of the negative current collector disk is D7, and the diameter of the core is D5, satisfying: D2 / D5 = 80% - 95%, D7 / D5 = 90% - 98%.

[0028] By reasonably designing the sizes of the positive current collector disk and the negative current collector disk, the welding area between the two and the core can be effectively increased, so as to improve the welding effect and facilitate the design of welding tools.

[0029] In a possible implementation, the distance between the centers of the second hole and the first hole is L2, satisfying: L2 / D2 = 25% - 35%.

[0030] By reasonably designing the distance L2 between the second hole and the first hole, while further ensuring the area of the weldable region, the infiltration effect of the electrolyte is improved.

[0031] In a possible implementation, the raised platform is circular and located in the central area of the second side. Taking the diameter of the raised platform as D8, satisfying D8 / D7 = 28% - 38%.

[0032] By reasonably designing the size of the raised platform, the welding effect with the bottom of the shell is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 is an exploded schematic view of a cylindrical lithium battery according to an embodiment of the present application;

[0035] Figure 2 is a cross-sectional view of the cap in a cylindrical lithium battery according to an embodiment of the present application;

[0036] Figure 3 It is a top view schematic diagram of the explosion-proof valve sheet in a cylindrical lithium battery according to an embodiment of the present application;

[0037] Figure 4 is Figure 3 a cross-sectional schematic diagram of the explosion-proof valve sheet in;

[0038] Figure 5 is Figure 4 a partial schematic diagram at position A in;

[0039] Figure 6 is Figure 4 a partial schematic diagram at position B in;

[0040] Figure 7 It is a structural schematic diagram of the connection between the positive current collector plate and the winding core in a cylindrical lithium battery according to an embodiment of the present application;

[0041] Figure 8 It is a top view schematic diagram of the positive current collector plate in a cylindrical lithium battery according to an embodiment of the present application, wherein the tail body part is in an unfolded state;

[0042] Figure 9 It is a structural schematic diagram of the connection between the negative current collector plate and the winding core and the bottom of the shell in a cylindrical lithium battery according to an embodiment of the present application;

[0043] Figure 10 is Figure 9 a cross-sectional schematic diagram of the negative current collector plate in.

[0044] Reference numerals:

[0045] 110 - Outer shell, 111 - Bottom of the shell, 112 - Side wall, 1121 - Necking part, 113 - Inner cavity, 114 - Opening;

[0046] 120 - Cap, 121 - Top cover, 122 - Explosion-proof valve sheet, 1221 - Notch assembly, 1221a - First notch, 1221b - Second notch, 1222 - Thinning part, 1223 - Groove, 1224 - Welding platform, 123 - Insulating plate, 124 - Terminal plate, 125 - Insulating ring;

[0047] 130 - Positive current collector plate, 131 - Plate body part, 1311 - First hole, 1312 - Second hole, 1313 - First side, 1314 - Arc, 1315 - Second side, 132 - Tail body part, 1321 - Fifth side, 1322 - Sixth side, 1323 - Fourth side, 1324 - Weakening part;

[0048] 140 - Winding core, 141 - Positive extreme, 142 - Negative extreme, 143 - Winding core hole;

[0049] 150 - Negative current collector plate, 151 - First side, 1511 - Concave portion, 1512 - Welding area, 152 - Second side, 1521 - Raised platform. Detailed implementation manners

[0050] The embodiments of the present implementation manner will be described in detail below. The examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present implementation manner, and should not be construed as a limitation to the present implementation manner.

[0051] In the description of the present implementation manner, it should be understood that for the orientation description, such as up, down, front, back, left, right, etc., the orientation or positional relationship indicated is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present implementation manner and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present implementation manner.

[0052] In the description of the present implementation manner, the meaning of several is one or more, the meaning of multiple is two or more, greater than, less than, exceeding, etc. are understood not to include the present number, and above, below, within, etc. are understood to include the present number. If there is a description of first and second, it is only for the purpose of distinguishing technical features and should not be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features or implicitly indicating the sequence relationship of the indicated technical features.

[0053] In the description of the present implementation manner, unless otherwise clearly defined, words such as setting, installing, connecting, etc. should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above words in the present implementation manner in combination with the specific content of the technical solution.

[0054] 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), the 46 series (cylindrical lithium batteries with an outer diameter of 46 mm), which are not limited herein. Specifically, as Figure 1 shown, the cylindrical lithium battery includes a housing 110, a cap 120, a positive current collector plate 130, a winding core 140, and a negative current collector plate 150. Among them, the positive end 141 of the winding core 140 is connected to the cap 120 through the positive current collector plate 130, and the negative end 142 of the winding core 140 is connected to the housing 110 through the negative current collector plate 150. Thus, the cap 120 serves as the positive electrode of the cylindrical lithium battery, and the housing 110 serves as the negative electrode of the cylindrical lithium battery for electrically connecting to an external electrical device.

[0055] The housing 110 will be introduced in detail below.

[0056] As Figure 1 shown, in combination with Figure 9 , the overall housing 110 is 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 bottom case 111 and a side wall 112. Among them, the bottom case 111 is circular, the side wall 112 extends upward along the edge of the bottom case 111, the bottom case 111 and the side wall 112 jointly define an inner cavity 113, and the top end of the side wall 112 has an opening 114, and the opening 114 communicates with the inner cavity 113.

[0057] As Figure 1 shown, the side wall 112 forms an inwardly concave necking portion 1121 along the circumferential direction near the opening 114. The necking portion 1121 is used to seal the cap 120. The necking portion 1121 can be formed by a rolling groove and a sealing process. And, in the sealing process, the cap 120 completely closes the opening 114, and seals the negative current collector plate 150, the winding core 140, the positive current collector plate 130, etc. in the inner cavity 113, so as to form a sealed electrochemical system in the housing 110.

[0058] The following details the cap 120.

[0059] It can be understood that the cap 120 and the housing 110 together serve as a physical barrier to isolate the active materials of the cylindrical lithium battery from the outside. And, when the gas pressure inside the battery exceeds a preset value, the explosion-proof valve piece 122 of the cap 120 opens to release the pressure, so as to avoid the battery from deforming and bulging or even catching fire or exploding.

[0060] As Figure 2 shown, the cap 120 includes a top cover 121, an explosion-proof valve piece 122, an insulating plate 123, a terminal plate 124, and an insulating ring 125 located at the outer edge. Among them, the top cover 121, the explosion-proof valve piece 122, and the terminal plate 124 are stacked in sequence from top to bottom and are electrically connected to each other pairwise. After the cap 120 is sealed and connected to the housing 110, the top cover 121 is exposed outside the housing 110, and it serves as the positive terminal for electrical connection with the positive electrode of the external electrical device. The bottom surface of the terminal plate 124 is connected to the positive current collector plate 130. For example, the positive current collector plate 130 and the terminal plate 124 are welded together. Thus, an electrical connection is formed between the two, so as to conduct the top cover 121 and the positive end 141 of the winding core 140. The following details the explosion-proof valve piece 122 that makes up the cap 120.

[0061] Referring to Figures 3 to 4 , the explosion-proof valve piece 122 is a single-piece component processed from aluminum material, and the overall shape is a circular thin disk or thin plate structure. Along the thickness direction, it has a top surface and a bottom surface facing away from each other. Among them, after being assembled into the cylindrical lithium battery, this bottom surface ( Figure 4The lower middle part) faces one side of the core 140, and the top surface ( Figure 4 The upper middle part) faces one side of the top cover 121. Among them, the explosion-proof valve piece 122 is provided with a notch assembly 1221 on the top surface side. The notch assembly 1221 includes a circular first notch 1221a and a linearly extending second notch 1221b. The second notch 1221b is located within the area defined by the first notch 1221a, and both ends of the second notch 1221b are connected to the first notch 1221a. That is, the first notch 1221a presents a closed figure with its head and tail connected. The first notch 1221a is preferably a closed circle, and the second notch 1221b is linear. Among them, at least one of the first notch 1221a and the second notch 1221b breaks when the internal pressure of the cylindrical lithium battery exceeds a preset value, so that the explosion-proof valve piece 122 is opened, and moreover, the first broken one of the first notch 1221a and the second notch 1221b can drive the other one to break as well.

[0062] It can be understood that since the explosion-proof valve piece 122 of the embodiment of the present application is provided with a circular first notch 1221a and a linear second notch 1221b on the explosion-proof valve piece 122, and both ends of the second notch 1221b are connected to the first notch 1221a, therefore, when abnormal states such as overheating and short circuit occur inside the battery, resulting in a sharp rise in the internal air pressure, when the air pressure value in the edge area reaches the preset value first, the first notch 1221a breaks first, and the internal gas of the battery rushes out from the gap generated by the break of the first notch 1221a to relieve the pressure in time. Moreover, during the breaking process of the first notch 1221a, it will also drive the second notch 1221b to break, so as to be able to enlarge the opening area of the explosion-proof valve piece 122 and improve the pressure relief effect; when the air pressure value in the middle area reaches the preset value first, the second notch 1221b breaks first, and the internal gas of the battery rushes out from the gap generated by the break of the second notch 1221b to relieve the pressure in time. Moreover, during the breaking and opening process of the second notch 1221b, it will also drive the first notch 1221a to break, so as to be able to enlarge the opening area of the explosion-proof valve piece 122 and improve the pressure relief effect. Thus, when the gas pressure inside the battery exceeds the preset value, the explosion-proof valve piece 122 can be quickly and effectively opened to release the pressure, thereby improving the safety of the battery.

[0063] It should be noted that if the first notch 1221a and the second notch 1221b are not connected, they can only break separately to form a gap for pressure relief. In this case, the pressure relief effect is not good, and the purpose of quickly and effectively relieving the pressure of the battery proposed in this application cannot be achieved. Therefore, in the embodiments of this application, the first notch 1221a and the second notch 1221b that make up the notch assembly 1221 are set to be connected, that is, they intersect. Therefore, after any one of them breaks, it can extend to the other, causing the other to also break. Therefore, the opening area of the explosion-proof valve sheet 122 can be enlarged, so as to quickly relieve the pressure of the battery.

[0064] It can be understood that although more complex internal notches such as cross-shaped notches can be used to replace the second notch 1221b to achieve the purpose of timely bursting when the pressure in the middle area of the battery rises, however, this will significantly increase the processing difficulty of the explosion-proof valve sheet 122, resulting in a decrease in the yield rate and an increase in cost. In the embodiments of this application, only a straight second notch 1221b is provided inside the explosion-proof valve sheet 122, which can effectively achieve quick and effective pressure relief of the battery while being easy to process and having a low cost, and has better economic benefits.

[0065] It can be understood that the first notch 1221a and the second notch 1221b are structures formed by removing materials on the explosion-proof valve sheet 122. Therefore, the explosion-proof valve sheet 122 is thinner at the positions where the first notch 1221a and the second notch 1221b are located than at the other positions. When the internal pressure of the battery rises and exceeds the preset value, according to the specific pressure position distribution, one or both of the first notch 1221a and the second notch 1221b will deform. When the deformation accumulates to a certain extent, the first notch 1221a and the second notch 1221b will break, and the broken material will be turned over by the pressure to generate a gap at the break, and the high-pressure gas inside the battery will be released through the gap.

[0066] In some embodiments, such as Figure 3As shown, the first notch 1221a is circular, and the second notch 1221b is arranged to pass through the center of the first notch 1221a. That is, the second notch 1221b exactly serves as the diameter of the circular figure shown by the first notch 1221a. Thus, taking the diameter of the first notch 1221a as D1 and the length of the second notch 1221b as L1, then L1 = D1 is satisfied. Thereby, the second notch 1221b divides the first notch 1221a into two symmetrical parts, facilitating the processing and construction of the first notch 1221a and the second notch 1221b. Moreover, after the explosion-proof valve piece 122 is assembled to the cylindrical lithium battery, the second notch 1221b is located in the central region of the cylindrical lithium battery, so that the explosion-proof valve piece 122 can be smoothly opened to relieve pressure. Further, it can be understood that, in order to facilitate the construction of the circular first notch 1221a and the linear second notch 1221b, the first notch 1221a can be arranged to be concentric with the explosion-proof valve piece 122.

[0067] As Figure 4 shown, in some embodiments, the explosion-proof valve piece 122 is provided with a thinning portion 1222 extending in the radial direction, and the first notch 1221a is arranged within the radial range where the thinning portion 1222 is located. Specifically, the thinning portion 1222 can be realized by opening a groove 1223 on one side of the explosion-proof valve piece 122. The thinning portion 1222 can effectively cause the notch assembly 1221 to break when the opening condition is met to relieve the pressure of the battery, and at the same time ensure that the explosion-proof valve piece 122 has sufficient strength and rigidity, facilitating processing and assembly.

[0068] As Figure 5 and Figure 6 shown, relative to the surface of the explosion-proof valve piece 122, the first notch 1221a has a depth H1, and the second notch 1221b has a depth H2. It can be understood that if H1 and H2 are larger, that is, the first notch 1221a and the second notch 1221b are deeper, then the first notch 1221a and the second notch 1221b are prone to breakage and the opening pressure will be too small. If H1 and H2 are larger, that is, the first notch 1221a and the second notch 1221b are shallower, then the first notch 1221a and the second notch 1221b are not prone to breakage and the opening pressure will be too large, and the gas inside the battery cannot be released in time, increasing the safety risk. Therefore, in some embodiments, the ratio of the depth H1 of the first notch 1221a to the thickness T1 of the thinning portion 1222 is between 30% and 60%, that is, 30% ≤ H1 / T1 ≤ 60% is satisfied. More preferably, 40% ≤ H1 / T1 ≤ 55%. The specific values of H1 and H2 can be determined according to the opening pressure and the thickness of the thinning portion 1222 (or the explosion-proof valve piece 122).

[0069] 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 annularly arranged 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 through the center of the explosion-proof valve plate 122 on the end face of the explosion-proof valve plate 122. Due to requirements such as strength and installation, the thickness of the explosion-proof valve plate 122 is usually different in different regions along the radial direction. For example, the wall thickness of the inner part of the explosion-proof valve plate 122 adjacent to the thinning part 1222 is thicker than that of the thinning part 1222, and the wall thickness changes in a stepped 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 this welding platform 1224. Therefore, in order to ensure that both the first notch 1221a and the second notch 1221b located in different regions of the explosion-proof valve plate 122 can be smoothly opened when the pressure reaches the preset value, in some embodiments, the depth of the first notch 1221a is different from the depth of the second notch 1221b.

[0070] Further, in some embodiments, the depth H1 of the first notch 1221a is less than the depth H2 of the second notch 1221b. By increasing the depth of the second notch 1221b, the influence of the increased thickness of the explosion-proof valve plate 122 in the middle region on the second notch 1221b can be reduced to ensure that the explosion-proof valve plate 122 is smoothly opened at the second notch 1221b.

[0071] 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 influence of the stepped change in the thickness of the explosion-proof valve plate 122 along the radial direction can be reduced to ensure that the explosion-proof valve plate 122 is smoothly opened at the second notch 1221b.

[0072] The positive current collector plate 130 is introduced in detail below.

[0073] As Figure 7 and Figure 8 shown, the positive current collector plate 130 includes a plate body part 131 and a tail body part 132 that are connected to each other. The plate body part 131 is used to connect to the core 140, and the tail body part 132 is used to connect to the cap 120 to form a path between the core 140 and the cap 120. In this application, the connection between the plate body part 131 and the core 140 and the connection between the tail body part 132 and the cap 120 can both adopt any connection method well-known to those skilled in the art, such as welding; the connection between the tail body part 132 and the plate body part 131 can be any fixed connection method. To ensure firm connection and structural strength, it is preferably integrally connected.

[0074] As Figure 8As shown, in order to match the circular cross-section of the core 140 and facilitate the welding between the disk body portion 131 and the core 140, the shape of the disk body portion 131 is a closed axisymmetric figure formed by sequentially connecting the first side 1313, the arc 1314, the second side 1315, and the third side 1316 end to end. Both the first side 1313 and the second side 1315 are connected to one end of the tail body portion 132. It should be noted that the third side 1315 is a virtual side line proposed for the convenience of describing the disk body portion 131, and there is no such side in the actual product. Therefore, in Figure 8 it is marked with a dotted line for distinction.

[0075] In order to improve the efficiency of injecting electrolyte during the battery production process, the disk body portion 131 usually has holes for the electrolyte to pass through. To ensure that the solid area of the disk body portion 131 still accounts for more than 75% of the total area of the disk body portion 131 after punching, it is convenient for welding with the core 140.

[0076] In some embodiments, the diameter D2 of the disk body portion 131 is 80%-95% of the diameter D5 of the core 140. The diameter D2 of the disk body portion 131 refers to the longest line segment between two points on the arc 1314, and the diameter D5 of the core 140 refers to the diameter of the circular cross-section of the core 140. According to actual needs, the size of the diameter D2 of the disk body portion 131 is, for example, 15-23 mm. The diameter of the disk body portion 131 within the preferred range ensures a large contact area between the disk body portion 131 and the core 140, increases the weldable area, and expands the adaptation range of the wire bonding length and shape.

[0077] In some embodiments, a first hole 1311 is provided at the center of the disk body portion 131 for injecting electrolyte into the battery. The center of the above-mentioned disk body portion 131 can be the center of the circle corresponding to the arc 1314. The core 140 is made by a winding process, and a circular core hole 143 is formed at the center position of the core 140 after winding. To match the shape of the core hole 143, the shape of the first hole 1311 is preferably circular.

[0078] In some embodiments, at least one second hole 1312 is provided around the first hole 1311 for assisting the infiltration of the electrolyte. Preferably, the second hole 1312 is a circular hole. Further preferably, the area of a single second hole 1312 is 0.3-0.5 times the area of the first hole 1311, and the sum of the areas of all the second holes 1312 is 0.9-1.5 times the area of the first hole 1311. If the area of the second hole 1312 is too small compared to the area of the first hole 1311, the effect of assisting infiltration will not be obvious; if the area of the second hole 1312 is too large, the weldable area of the disk body portion 131 will be significantly reduced, affecting the connection between the disk body portion 131 and the core 140.

[0079] In some embodiments, the diameter D3 of the first hole 1311 is 1.4 - 1.8 times the diameter D6 of the core hole of the core electrode group; further, the diameter D3 of the first hole 1311 is 25% - 35% of the diameter D2 of the disk body portion 131. According to actual needs, the diameter D3 of the first hole 1311 is, for example, 4 - 8 mm. Within this diameter range, the first hole 1311 can achieve a balance between the liquid injection efficiency and the weldable area, while ensuring the safety of welding. If the diameter D3 of the first hole 1311 is too small, it is not conducive to the infiltration of the injected liquid, and when using the resistance welding process at the bottom of the battery, the electrode head extending into the core hole 143 of the core 140 may have an undesired contact with the current collector plate, posing an interference risk; if the diameter D3 of the first hole 1311 is too large, the weldable area will be correspondingly reduced, restricting the welding process between the disk body portion 131 and the core 140.

[0080] In some embodiments, the distance L2 between the center of the second hole 1312 and the center of the first hole 1311 is 25% - 35% of the diameter D2 of the disk body portion 131. According to actual needs, L2 is, for example, 4.5 - 7 mm. By reasonably designing the distance L2 between the second hole 1312 and the first hole 1311, it helps to improve the infiltration effect of the electrolyte while ensuring the area of the weldable region. If the distance L2 between the second hole 1312 and the first hole 1311 is too small, the infiltration effect of the electrolyte cannot be significantly improved; if the distance L2 between the second hole 1312 and the first hole 1311 is too large, the second hole 1312 is too close to the edge of the disk body portion 131, thus restricting the battery encapsulation. If the encapsulation blocks the second hole 1312, the electrolyte cannot be injected through the second hole 1312.

[0081] For the convenience of processing and improving the yield rate, in a preferred embodiment, the diameter D4 of the second hole 1312 is 50% - 70% of the diameter D3 of the first hole 1311, and the diameter D4 of the second hole 1312 is, for example, 2 - 4.8 mm. If the diameter D4 of the second hole 1312 is less than the preferred diameter range, it is difficult to achieve the function of auxiliary infiltration; if the diameter D4 of the second hole 1312 is greater than the preferred diameter range, the weldable area of the disk body portion 131 will be reduced. It can be understood that the number of the second holes 1312 can be determined according to the actual welding process. The number of the welding areas is n, and the number of the second holes 1312 is n - 1, where n ≥ 2.

[0082] As Figure 8As shown, the tail body portion 132 includes a fifth side 1321 and a sixth side 1322 along its length direction, and a fourth side 1323 away from the disk body portion 131. The two ends of the fifth side 1321 are respectively connected to the fourth side 1324 and the first side 1311, and the two ends of the sixth side 1322 are respectively connected to the fourth side 1324 and the second side 1313. The included angle θ1 between the fifth side 1321 and the first side 1313 is 45 - 90°, and the included angle θ2 between the sixth side 1322 and the second side 1315 is 45 - 90°. It can be understood that if the included angles θ1 and θ2 are too small, the bending of the tail body portion 132 will cause stress to concentrate too much at the included angles θ1 and θ2, resulting in deformation or even cracking of the disk body portion 131; if the included angles θ1 and θ2 are too large, it is impossible to ensure that the disk body portion 131 has sufficient weldable area. In addition, the reasonable angle design of the included angles θ1 and θ2 also helps the electrolyte to penetrate into the battery through the included angles θ1 and θ2.

[0083] To improve battery safety, in some embodiments, at least one weakening portion 1324 is provided on the tail body portion 132 as a fusing structure. Specifically, the weakening portion 1324 is a pair of grooves. Through this design, the width of the tail body portion 132 can be reduced. When the battery is in thermal runaway, the current converges at this place, the heat rises and reaches the melting point, causing the tail body portion 132 to fuse, achieving the effect of current interruption.

[0084] In some embodiments, the minimum cross-sectional area of the tail body portion 132 at the weakening portion 1324 is 45% - 65% of the overall cross-sectional area of the tail body portion 132. Specifically, the minimum cross-sectional area S1 of the tail body portion 132 at the weakening portion 1324 is the cross-sectional area at the narrowest position of the groove 22, and the overall cross-sectional area of the tail body portion 132 is the cross-sectional area at the position on the tail body portion 132 other than the weakening portion 1324. Within a reasonable range of the minimum cross-sectional area, the tail body portion 132 can achieve a balance between battery safety and low internal resistance. When the minimum cross-sectional area is too large, the tail body portion 132 cannot fuse quickly during thermal runaway, increasing the safety risk; conversely, when the minimum cross-sectional area is too small, on the one hand, the fusing sensitivity will be too high, and on the other hand, the internal resistance will increase, seriously affecting the normal use of the battery.

[0085] In some embodiments, the material of the positive current collector disk 130 is aluminum. On the one hand, aluminum has the characteristics of low internal resistance and good electrical conductivity. On the other hand, the melting point of aluminum is relatively low. When the battery is in thermal runaway, the weakening portion can fuse to cut off the current.

[0086] The core 140 will be introduced in detail below.

[0087] It can be understood that the core 140 is formed by winding a positive electrode sheet, a negative electrode sheet, and a separator layer, as Figure 1As shown, the core 140 is generally cylindrical, and in order to smoothly pass through the opening 114 into the inner cavity 113 of the outer shell 110, its diameter D5 is slightly smaller than the inner diameter of the outer shell 110. As Figure 9 shown, it can be understood that after the core 140 is inserted into the shell, it is located within the region defined by the necking portion 1121 and the bottom 111 of the outer shell 110, that is, in the lower cavity 1132.

[0088] In this embodiment, the core 140 is provided with opposite positive and negative ends 141 and 142. The positive end 141 is connected to the cap 120 through the positive current collector plate 130, and the negative end 142 is connected to the outer shell 110 through the negative current collector plate 150.

[0089] It can be understood that in order to improve the energy density of the battery and the welding effect with the positive current collector plate 130 and the negative current collector plate 150, the positive end 141 and the negative end 142 can be formed by flattening the full tab. For example, the full tab foil of the positive and negative current collectors is integrally rotated and kneaded by a mechanical conical roller for a certain stroke. Thus, on the one hand, the positive end 141 and the negative end 142 formed by the flattening process are stacked densely, without wasting space in the longitudinal direction. Therefore, the utilization rate of the internal space of the outer shell 110 is relatively high, and the energy density of the battery can be further improved. On the other hand, the cross-sections of the positive flattened structure 141 and the negative flattened structure 142 formed by the flattening process are flat. After they are respectively abutted against the positive current collector plate 130 and the negative current collector plate 150, the fitting effect is good, which is conducive to laser welding and can effectively reduce process defects such as false soldering.

[0090] In addition, in the winding process, a through core hole 143 is formed in the middle of the core 140 in the axial direction. The diameter D6 of the core hole 143 needs to consider the balance between the injection efficiency and the weldable area, while ensuring the safety of welding.

[0091] The following details the negative current collector plate 150.

[0092] As Figure 9 and Figure 10 shown, the negative current collector plate 150 is generally circular. In the thickness direction, the negative current collector plate 150 has a first side 151 and a second side 152 facing away from each other. Since the second side 152 is provided with a raised platform 1521 to be introduced below, when welding the negative current collector plate 150 to the outer shell 110 and the core 140, the direction needs to be distinguished. Specifically, the second side 152 is welded to the bottom 111 of the shell through the raised platform 1521, and the first side 151 is welded to the negative end 142 of the core 140. Thus, the welding connection between the core 140, the negative current collector plate 150, and the outer shell 110 is realized, and a path is formed among the three. That is, the negative current collector plate 150 indirectly connects the core 140 and the outer shell 110.

[0093] To ensure good fit between the raised platform 1521 and the surface of the outer shell 110, in this embodiment, the negative current collector plate 150 is provided with a raised platform 1521 having 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 adapted to abut against the inner surface of the bottom shell 111. Moreover, the flatness of the surface of the raised platform 1521 is 0.01 - 0.05 mm. It can be understood that since 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 is the top surface of the second side 152. After the negative current collector plate 150 is assembled into the outer shell 110, the surface of the raised platform 1521 will abut against the inner surface of the bottom shell 111. That is, the surface of the raised platform 1521 and the inner surface of the bottom shell 111 are in close fit with each other, forming a surface-to-surface contact connection. Then, the area where the raised platform 1521 overlaps with the bottom shell 111 can be laser penetration welded through the outer surface 1112 of the bottom plate, so that the raised platform 1521 is welded to the outer shell 110. It can also be understood that if the flatness of the raised platform 1521 is too large, the fit effect with the inner surface of the bottom shell 111 will be poor, thus affecting the welding quality; on the contrary, if the flatness of the raised platform 1521 is too small, it is not easy to process and the cost is too high.

[0094] In this embodiment, since the ratio of the diameter D7 of the negative current collector plate 150 to the diameter D5 of the core 140 is set between 90% and 98%, therefore, the weldable area between the negative current collector plate 150 and the core 140 can be effectively increased, and the welding processability is good. At the same time, a raised platform 1521 with a smaller area is provided on the second side 152 of the negative current collector plate 150. Due to the smaller area of the raised platform 1521, during the processing, it can ensure that it has good surface flatness, so that the fit effect between the surface of the raised platform 1521 and the inner surface of the bottom shell 111 is better, and welding quality problems such as virtual welding between the two can be effectively avoided. The battery using this negative current collector plate 150 has better performance and yield.

[0095] For the purpose of facilitating processing and reducing costs, in some embodiments, the raised platform 1521 is formed by stamping the negative current collector plate 150, that is, the raised platform 1521 and the negative current collector plate 150 are integrally formed. Thus, through reasonable stamping die design, the negative current collector plate 150 of this embodiment can be efficiently processed, and the dimensional accuracy of the negative current collector plate 150 and the raised platform 1521 is high, and the surface quality is good, which is convenient for realizing the welding with the core 140 and the housing 110. Of course, it is not limited thereto, and the raised platform 1521 can also be formed in other ways. For example, the raised platform 1521 can be a sheet metal member with excellent welding performance and conductivity, and the metal member can be combined with the surface of the second side 152 of the negative current collector plate 150 by pressing to form the raised platform 1521.

[0096] In some embodiments, the raised platform 1521 is formed in the central region of the second side 152. Thus, after the negative current collector plate 150 is assembled into the housing 110, the raised platform 1521 can be aligned with the central region of the bottom 111 of the housing, which is convenient for welding the housing 110 and the raised platform 1521 through a welding device.

[0097] Furthermore, the shape of the raised platform 1521 is circular. In this way, the raised platform 1521 can be concentrically arranged with the negative current collector plate 150, which is convenient for stamping and forming through a stamping die. Of course, the shape of the raised platform 1521 is not limited to circular. For example, the raised platform 1521 can also be square, triangular and other shapes.

[0098] As Figure 9 and Figure 10 shown, it can be understood that the raised platform 1521 is punched out on the second side 152 of the negative current collector plate 150 through a stamping process. Correspondingly, a recess 1511 is formed at the position corresponding to the raised platform 1521 on the first side 151. For the purpose of facilitating the welding of the negative current collector plate 150 and the core 140, in some embodiments, around the recess 1511, the first side 151 has an annular welding area 1512, and the surface of the welding area 1512 is adapted to abut against the negative terminal 142 of the core 140. For example, the welding area 1512 is also set to have a flat surface so that the surfaces of the two can be closely attached to each other to improve the welding quality.

[0099] As Figure 10As shown, in some embodiments, if the diameter of the raised platform 1521 is D8, it satisfies D8 / D7 = 28% - 38%. As mentioned above, the diameter D7 of the negative current collector plate 150 is generally the same as the diameter of the core 140. If the diameter of the raised platform 1521 is too large, the flatness of its surface will deteriorate, and its fitting effect with the inner surface of the bottom case 111 will be poor, thus affecting the welding quality. On the contrary, if the diameter of the raised platform 1521 is too small, the weldable area of the raised platform 1521 will be small, and it is easy to have a solder joint break during welding, which will increase the process difficulty of subsequent welding and lead to an increase in cost.

[0100] In some embodiments, the material of the negative current collector plate 150 is copper, and the surface of the negative current collector plate 150 is plated with a nickel layer. Compared with the negative current collector plate 150 made of copper-nickel alloy, using copper as the base material has the characteristic of extremely low internal resistance. At the same time, by plating a nickel layer on the surface of the negative current collector plate 150, the corrosion resistance of the negative current collector plate 150 can be effectively improved.

[0101] Furthermore, the thickness of the nickel layer is set to 0.08 - 1.5 μm, and more preferably 0.9 - 1.1 μm. It can be understood that if the thickness of the nickel layer is too small, it cannot play the role of anti-oxidation. On the contrary, if the thickness of the nickel layer is too thick, on the one hand, it increases the difficulty of the nickel plating process and the cost, and on the other hand, it will increase the hardness of the negative current collector plate 150, resulting in a decrease in the plasticity of the negative current collector plate 150. At the same time, it will also increase the internal resistance and lead to a decrease in battery performance.

[0102] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this implementation. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0103] Although the embodiments of this implementation have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and purposes of this implementation. The scope of this implementation is defined by the claims and their equivalents.

Claims

1. A cylindrical lithium battery, characterized in that, It includes a housing (110) with a bottom shell (111), a cap (120), a positive current collector plate (130), a wound core (140) with a wound core hole (143), and a negative current collector plate (150). The positive end (141) of the wound core (140) is connected to the cap (120) through the positive current collector plate (130), and the negative end (142) of the wound core (140) is connected to the bottom shell (111) through the negative current collector plate (150), where: At least one of the positive end (141) and the negative end (142) is formed by flattening a full tab; The cap (120) is arranged on the top of the housing (110) and includes an explosion-proof valve sheet (122) and a terminal plate (124) arranged in a stacked manner. The explosion-proof valve sheet (122) is provided with a first notch (1221a) and a second notch (1221b). The first notch (1221a) is a closed circle with its head and tail connected, and the second notch (1221b) is in the shape of a line segment. The first notch (1221a) intersects with the second notch (1221b); The positive current collector plate (130) includes a plate body part (131) and a tail body part (132) connected to each other. The plate body part (131) is connected to the positive end (141), and the tail body part (132) is connected to the terminal plate (124). A circular first hole (1311) is provided at the center of the plate body part (131), and at least one circular second hole (1312) is arranged on the periphery of the first hole (1311); the sum of the areas of all the second holes (1312) is 0.9 - 1.5 times the area of the first hole (1311); the diameter D3 of the first hole (1311) is 1.4 - 1.8 times the diameter D6 of the wound core hole (143); The negative current collector plate (150) has opposite first side (151) and second side (152). The first side (151) is connected to the negative end (142), and a raised platform (1521) with a flat surface is provided on the second side (152). The raised platform (1521) is connected to the inner surface of the bottom shell (111), and the flatness of the surface of the raised platform (1521) is 0.01 - 0.05 mm.

2. The cylindrical lithium battery according to claim 1, wherein The explosion-proof valve sheet (122) is provided with a thinning part (1222) extending in the radial direction. The first notch (1221a) is arranged within the radial range where the thinning part (1222) is located. The thickness of the thinning part (1222) is T1, and the depth of the first notch (1221a) is H1, satisfying: H1 / T1 = 30% - 60%; the shape of the plate body part (131) is a closed axisymmetric figure formed by sequentially connecting a first side (1313), an arc (1314), a second side (1315), and a third side (1316) end to end. Both the first side (1313) and the second side (1315) are connected to the tail body part (132).

3. The cylindrical lithium battery according to claim 2, wherein The diameter D1 of the first notch (1221a) is equal to the length L1 of the second notch (1221b); the tail body portion (132) includes a fifth side (1321) and a sixth side (1322) along the length direction of the tail body portion (132) and a fourth side (1323) away from the disk body portion (131). Two ends of the fifth side (1321) are respectively connected to the fourth side (1323) and the first side (1313), and two ends of the sixth side (1322) are respectively connected to the fourth side (1323) and the second side (1315). The included angle θ1 between the fifth side (1321) and the first side (1313) is 45-90°, and the included angle θ2 between the sixth side (1322) and the second side (1315) is 45-90°.

4. The cylindrical lithium battery according to claim 1, wherein, The depth H1 of the first notch (1221a) is less than the depth H2 of the second notch (1221b), and the depth in the middle of the second notch (1221b) is greater than the depths at both ends; a weakening portion (1324) is provided on the tail body portion (132), and the cross-sectional area of the weakening portion (1324) accounts for 45% to 65% of the cross-sectional area of the tail body portion (132).

5. The cylindrical lithium battery according to any one of claims 1 to 4, characterized in that, One side of the disk body portion (131) facing the positive extreme (141) abuts against the formed positive extreme (141). Taking the diameter of the disk body portion (131) as D2 and the diameter of the second hole (1312) as D4, it satisfies: D3 / D2 = 25% to 35%, D4 / D3 = 50% to 70%.

6. The cylindrical lithium battery according to any one of claims 1 to 4, characterized in that, The raised platform (1521) is integrally formed by stamping the negative current collector disk (150). A recessed portion (1511) is formed on the first side (151) at a position corresponding to the raised platform (1521). Around the recessed portion (1511), a welding area (1512) is formed on the first side (151), and the surface of the welding area (1512) abuts against the formed negative extreme (142).

7. The cylindrical lithium battery according to any one of claims 1 to 4, characterized in that The material of the positive current collector disk (130) is aluminum, the material of the negative current collector disk (150) is copper, and a nickel layer is plated on the surface of the negative current collector disk (150), and the thickness of the nickel layer is 0.08 to 1.5 μm.

8. The cylindrical lithium battery according to any one of claims 1 to 4, characterized in that, The diameter of the disk body portion (131) is D2, the diameter of the negative current collector disk (150) is D7, and the diameter of the core (140) is D5, which satisfies: D2 / D5 = 80% - 95%, D7 / D5 = 90% to 98%.

9. The cylindrical lithium battery according to claim 8, wherein, The distance between the centers of the second hole (1312) and the first hole (1311) is L2, which satisfies: L2 / D2 = 25% - 35%.

10. The cylindrical lithium battery according to claim 8, wherein, The raised platform (1521) is circular and located in the central area of the second side (152). Taking the diameter of the raised platform (1521) as D8, it satisfies D8 / D7 = 28% to 38%.

Images