A cylindrical lithium-ion battery
By rationally setting the soldering area and structure of the positive and negative current collectors, the problems of high welding defect rate and increased internal resistance were solved, thereby improving the overall performance and production efficiency of the battery.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU RELIANCE ENERGY TECHNOLOGY CO LTD
- Filing Date
- 2025-06-05
- Publication Date
- 2026-05-26
AI Technical Summary
The welding area of the positive and negative current collectors in existing cylindrical batteries is unreasonable, which leads to increased internal resistance, weakened overcurrent capacity, and increased welding defect rate, affecting battery performance and production efficiency.
By rationally setting the ratio of the solder area of the positive current collector to that of the negative current collector, and controlling the length, width, and angle of the solder marks, a balance between welding efficiency and quality is ensured, and a cross-shaped solder mark structure is adopted.
It achieves battery internal resistance control, improves overcurrent capacity, reduces welding defect rate, and improves battery charge and discharge performance, cycle life and production efficiency.
Smart Images
Figure CN224288292U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of lithium battery technology, and in particular to a cylindrical lithium-ion battery. Background Technology
[0002] A cylindrical battery is a type of battery composed of components such as a positive electrode, a negative electrode, a separator, an electrolyte, and a casing, and its overall shape is cylindrical. Its structure typically includes components such as a casing, a cap, a positive electrode, a negative electrode, a separator, an electrolyte, a PTC element, gaskets, and a safety valve; these components work together to ensure that the battery can charge and discharge normally and provide protection in abnormal conditions.
[0003] A cylindrical battery and its assembly method are disclosed in CN118572267A. The cylindrical battery includes a casing, a positive current collector, a cell, a negative current collector, a first insulator, a sealing ring, a cap, and a second insulator. The casing is cylindrical in shape and open at one end. The outer edge of the cap and the inner circumference of the casing abut against the sealing ring to form a sealed cavity between the inner side of the cap and the inner side of the casing. The positive current collector, the cell, and the negative current collector are sequentially arranged in the sealed cavity along the opening direction of the casing. The casing, the positive current collector, the cell, the negative current collector, and the cap are sequentially connected to an external circuit to form a charging and discharging circuit.
[0004] The welding area of the current collectors in existing cylindrical batteries, whether at the positive or negative terminals, is unreasonable. In particular, when the welding area is too large, although it has limited effect on improving internal resistance, it prolongs welding time, reduces efficiency, and increases the risk of defects. When the welding area is too small, it leads to increased internal resistance, weakened overcurrent capacity, and increased temperature of the welding wire and battery. This seriously affects the overall charge and discharge performance, cycle life, and safety stability of the battery, and restricts the full realization of battery performance. Utility Model Content
[0005] In view of this, the present invention proposes a cylindrical lithium-ion battery that, by simultaneously and reasonably setting the solder area of the positive current collector and the negative current collector, can balance the control of battery internal resistance, the improvement of overcurrent capacity, and the balance between welding efficiency and quality; it avoids the increase in internal resistance and temperature caused by improper solder area, and also prevents the increase in welding defect rate, thereby effectively improving the overall performance of the battery.
[0006] The technical solution of this utility model is achieved as follows: This utility model provides a cylindrical lithium-ion battery, including a capped lower end plate, a positive electrode current collector, a core, and a negative electrode current collector, wherein...
[0007] The positive current collector includes a disc body and a tail body. The tail body is connected to the lower end plate of the cap through a first solder mark. The disc body is welded to the positive flat end of the core.
[0008] The cap's lower end plate has a central boss and an outer vent. The area of the lower end plate excluding the boss and vent is S30, and the area of the first solder mark is S31, satisfying: S31 / S30 = 4.5-8.5%.
[0009] The negative electrode current collector is welded to the negative electrode flattened end of the core through multiple second solder marks. The area of the negative electrode current collector is S20, and the total area of the multiple second solder marks is S2000, which satisfies: S2000 / S20 = 10%-20%.
[0010] Based on the above technical solution, preferably, the area S31 of the first solder mark 500 is 5-7 mm. 2 The area of a single second solder mark 600 is S200; and the area of a single second solder mark 600 and the area of the negative electrode current collector satisfy: S200 / S20 = 3% - 5%.
[0011] Based on the above technical solution, preferably, the height of the first solder mark is W30, the length of the first solder mark is L30, and the height of the first solder mark satisfies: W30 = 1-2mm, and the length of the first solder mark L30 satisfies: L30 = 3.5-4.5mm.
[0012] Based on the above technical solution, preferably, the length of the second solder mark is L20, the width of the second solder mark is W20, and the length of the second solder mark satisfies: L20 = 3.5-5.5mm, and the width of the second solder mark satisfies: W20 = 1.6-3.4mm.
[0013] Based on the above technical solution, preferably, the second solder mark includes multiple negative electrode solder lines arranged in parallel, and the minimum distance between two adjacent negative electrode solder lines is W202, which satisfies: W202 = 0.6-1.1mm.
[0014] Based on the above technical solution, preferably, the first solder mark includes a positive electrode solder wire, the width of which is W301, and satisfies: W301 = 0.2-0.4 mm; the width of the negative electrode solder wire is W203, and satisfies: W203 = 0.1-0.3 mm, and the minimum distance W202 between the width of the negative electrode solder wire and two adjacent negative electrode solder wires satisfies: W203 <W202。
[0015] Based on the above technical solutions, preferably, both the negative electrode bonding wire and the positive electrode bonding wire have multiple concave portions and convex portions, which are arranged alternately and continuously, and adjacent concave portions and convex portions are centrally rotationally symmetrical to form wavy negative electrode bonding wires and positive electrode bonding wires. The minimum distance between the outer convex tip of the concave portion and the inner convex tip of the convex portion of the negative electrode bonding wire is W201, and satisfies: W201=0.15-0.35mm.
[0016] Based on the above technical solutions, preferably, the concave angle of the positive electrode bonding wire is E, and satisfies: E = 25-65°; the convex angle of the positive electrode bonding wire is F, and satisfies: F = 25-65°; the concave angle of the negative electrode bonding wire is C, and satisfies: C = 70-120°; the convex angle of the negative electrode bonding wire is D, and satisfies: D = 70-120°.
[0017] Based on the above technical solutions, preferably, the first weld mark is located between the central boss and the outer peripheral pore; the number of the second weld marks is four, and the four second weld marks are symmetrically distributed in a cross shape.
[0018] Based on the above technical solutions, preferably, the radius of the lower end plate of the cap is R30, and satisfies: R30 = 5.29-7.29mm; the width of the tail body is L300, and satisfies: L300 = 5-7mm; the radius of the negative electrode current collector is R20, and satisfies R20 = 8.5-10.5mm.
[0019] The cylindrical lithium-ion battery of this invention has the following advantages over the prior art:
[0020] (1) By reasonably setting the proportion of the first solder area of the positive current collector and the total proportion of the second solder area of the negative current collector, the internal resistance of the battery, the overcurrent capacity, and the balance between welding efficiency and quality are achieved. This avoids the problems of increased internal resistance, weakened overcurrent capacity and increased temperature caused by too small solder area, and also prevents the problems of increased welding defect rate, increased manufacturing cost and decreased efficiency caused by too large solder area, thereby effectively improving the overall performance and production efficiency of the battery.
[0021] (2) By controlling the length and width of the first and second solder marks respectively, the welding wire can be effectively ensured to have sufficient current carrying capacity, reduce the internal resistance of the battery, improve the charging and discharging efficiency, extend the battery life, and improve production efficiency.
[0022] (3) By controlling the positive electrode welding wire angles E and F between 25-65° and the negative electrode welding wire angles C and D between 70-120°, the problem of excessive heat concentration and unreasonable welding wire layout can be effectively avoided, the overcurrent capacity of the welding wire can be improved, and the temperature at the welding wire can be reduced, thereby improving the battery's charge and discharge performance, cycle life and safety. Attached Figure Description
[0023] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0024] Figure 1 This is a schematic diagram of the cylindrical lithium-ion battery structure of this utility model;
[0025] Figure 2 This is a schematic diagram of the connection structure between the tail body and the lower end plate of the cap of the cylindrical lithium-ion battery of this utility model.
[0026] Figure 3 This is a schematic diagram showing the connection markings between the tail section and the lower end plate of the cap of the cylindrical lithium-ion battery of this utility model.
[0027] Figure 4 This is a schematic diagram of the first solder mark of the cylindrical lithium-ion battery of this utility model.
[0028] Figure 5 This is a schematic diagram of the negative electrode current collector structure of the cylindrical lithium-ion battery of this utility model;
[0029] Figure 6 This is a schematic diagram of the negative electrode current collector marking of the cylindrical lithium-ion battery of this utility model;
[0030] Figure 7 This is a schematic diagram of the second solder mark of the cylindrical lithium-ion battery of this utility model. Detailed Implementation
[0031] The technical solutions of this utility model will be clearly and completely described below with reference to the embodiments of this utility model. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this utility model.
[0032] like Figure 1-7As shown, a cylindrical lithium-ion battery of this utility model includes a positive current collector 1, a negative current collector 2, a core 3, and a cap lower end plate 4. The positive current collector 1 includes a plate body 11 and a tail body 12. The tail body 12 is connected to the cap lower end plate 4 via a first solder joint 500. The plate body 11 is welded to the flattened positive end of the core 3. The cap lower end plate 4 has a central boss 400 and vent holes 410 on its outer periphery. The area excluding the boss 400 and the vent 410 is S30, the area of the first solder mark 500 is S31, and the following conditions are met: S31 / S30 = 4.5-8.5%; the negative electrode current collector 2 is welded to the negative electrode flattened end of the core 3 through multiple second solder marks 600, the area of the negative electrode current collector 2 is S20, the total area of multiple second solder marks 600 is S2000, and the following conditions are met: S2000 / S20 = 10%-20%.
[0033] It should be noted that when the solder area ratio S31 / S30 is too small, the effective conductive contact area between the tail body 12 in the positive electrode current collector 2 and the lower end plate 4 of the cap is reduced. According to the inverse relationship between resistance and contact area, the reduction in contact area will lead to a significant increase in contact resistance, which in turn will increase the overall internal resistance of the battery. At the same time, the effective conductive area of the solder wire is reduced, and the current carrying capacity is weakened. When the battery is charged and discharged at high current, the solder wire cannot effectively conduct current in time, and the current will concentrate at the solder wire, generating a large amount of heat, causing the solder wire temperature to rise sharply, which in turn will drive up the overall battery temperature. This will not only seriously affect the charge and discharge performance of the battery, but also shorten the battery cycle life, reduce the battery safety and stability, and lead to a significant decline in the overall battery performance. When the solder area ratio S31 / S30 is too large, the excessively large solder area will lead to a longer solder wire, requiring more precise control and a longer soldering time during the soldering process. This increases the complexity and difficulty of soldering, and is prone to soldering defects such as weak soldering, incomplete soldering, and solder wire breakage, which will significantly increase the soldering defect rate. This will not only increase the manufacturing cost of the battery, but also reduce the efficiency of battery production and affect battery production capacity.
[0034] Specifically, in this embodiment, the area S30 of the lower end plate 4 of the cap, excluding the boss 400 and the vent 410, is 89.25 mm². 2 The area of the first solder mark 500 is S31 = 6 mm. 2 .
[0035] In this embodiment, when the total solder area ratio S2000 / S20 is too small, the current carrying capacity is weakened, the temperature rise at the solder line is too high, and the battery performance is reduced. When the total solder area ratio S2000 / S20 is too large, the optimization effect on the battery internal resistance is not obvious, but the expansion of the solder line area will reduce the welding reliability. The reduction of the distance between solder lines will cause heat concentration, making it difficult to dissipate heat quickly, which can easily cause quality problems such as soldering explosions and changes in solder line color, increasing the battery's safety hazards and manufacturing costs.
[0036] Specifically, in this embodiment, the area S20 of the negative electrode current collector 2 is 283.4 mm². 2 The total area of multiple second solder marks 600 is S2000 = 45mm. 2 Therefore, S2000 / S20 = 15.9%.
[0037] In this embodiment, by reasonably setting the area ratio of the first solder mark 500 on the positive current collector 2 and the total area ratio of the second solder mark 600 on the negative current collector 4, the internal resistance of the battery, the overcurrent capacity, and the balance between welding efficiency and quality are achieved. This avoids the problems of increased internal resistance, weakened overcurrent capacity, and increased temperature caused by too small a solder mark area, and also prevents the problems of increased welding defect rate, increased manufacturing cost, and decreased efficiency caused by too large a solder mark area, thereby effectively improving the overall performance and production efficiency of the battery.
[0038] In this embodiment, the area S31 of the first solder mark 500 is 5-7 mm. 2 The area of a single second solder mark 600 is S200; and the area of a single second solder mark 600 and the area of the negative electrode current collector 2 satisfy: S200 / S20 = 3% - 5%.
[0039] It should be noted that if the area S31 of the first solder mark 500 is too small, the solder mark area will be insufficient, resulting in a reduction in the effective contact area between the positive electrode of the battery and the lower end plate of the cap, increasing the contact resistance and thus increasing the internal resistance of the battery. At the same time, the overcurrent capacity will be weakened, and the solder wire will generate more heat when current passes through, causing the temperature to rise. The overall temperature of the battery will also rise, affecting the charge and discharge performance, cycle life, and safety of the battery. If the area S31 of the first solder mark 500 is too large, although the effect on improving the internal resistance of the battery is limited, the excessively large solder area will increase the soldering difficulty and the risk of solder wire defects, such as weak soldering or incomplete connections, leading to an increased soldering defect rate, increased manufacturing costs, and decreased production efficiency.
[0040] Specifically, in this embodiment, the area S31 of the first solder mark 500 is 6 mm. 2 .
[0041] It should be noted that if the area of a single second solder mark 600 is too small compared to the area of the negative electrode current collector 2, the solder mark area of the single second solder mark 600 will be too small, resulting in insufficient effective contact area between the negative electrode and the core, increasing the battery internal resistance, weakening the overcurrent capacity, and raising the solder wire temperature, thus affecting battery performance. If the area of a single second solder mark 600 is too large compared to the area of the negative electrode current collector 2, the improvement effect on the battery internal resistance will not be significant. However, increasing the solder mark area will increase the risk of welding defects, reduce the distance between solder wires, concentrate heat, make heat dissipation difficult, easily cause welding quality problems, and increase battery manufacturing costs and safety hazards.
[0042] Specifically, in this embodiment, the area S200 of a single second solder mark 600 is 11.25 mm. 2 Therefore, S200 / S20 = 3.97%.
[0043] In this embodiment, by controlling the ratio of the first solder area to the solder area of a single negative electrode current collector, a balance is achieved between the battery's internal resistance, current carrying capacity, welding efficiency, and quality. This avoids the problems of increased internal resistance, weakened current carrying capacity, and increased temperature caused by an excessively small solder area, while also preventing the problems of increased welding defect rate, increased manufacturing cost, and decreased efficiency caused by an excessively large solder area. This effectively improves the overall performance and production efficiency of the battery.
[0044] In this embodiment, the height of the first solder mark 500 is W30, the length of the first solder mark 500 is L30, and the height of the first solder mark 500 satisfies: W30 = 1-2mm, and the length of the first solder mark 500 L30 satisfies: L30 = 3.5-4.5mm.
[0045] It should be noted that when the length L30 or height W30 of the first solder mark 500 is too small, the effective contact area of the solder wire is reduced, resulting in weakened current carrying capacity and increased temperature at the solder wire. Operating the battery in a high-temperature environment will accelerate the reaction of internal chemical substances, leading to decreased battery performance and potentially even safety hazards. Conversely, when the length L30 or height W30 of the first solder mark 500 is too large, the improvement in battery internal resistance is not significant, but it increases soldering time and difficulty. Extended soldering time reduces production efficiency, while increased soldering difficulty may lead to a higher soldering defect rate, affecting battery quality and performance.
[0046] Specifically, in this embodiment, the height W30 of the first solder mark 500 is 1.5mm, and the length L30 of the first solder mark 500 is 4mm; therefore, based on the height and length of the first solder mark 500, the area S31 of a single first solder mark 500 is calculated to be 6mm². 2 .
[0047] In this embodiment, by controlling the length and height of the first solder mark 500, a balance between welding efficiency, welding quality and battery performance is achieved, effectively improving the overall performance and production efficiency of the battery.
[0048] In this embodiment, the length of the second solder mark 600 is L20, the width of the second solder mark 600 is W20, and the length of the second solder mark 600 satisfies: L20 = 3.5-5.5mm, the width of the second solder mark 600 satisfies: W20 = 1.6-3.4mm, and the second solder mark 600 includes multiple parallel negative electrode bonding wires 601, and the minimum distance between two adjacent negative electrode bonding wires 601 is W202, which satisfies: W202 = 0.6-1.1mm.
[0049] It should be noted that if the length L20 of the second solder mark (600mm) is too small, the current-carrying capacity of the solder wire will be weakened. During battery charging and discharging, due to the reduced effective area for current flow, local heat generation in the solder area increases, the temperature at the solder joint rises, and the battery's internal resistance also increases, severely affecting battery performance. If the length L20 of the second solder mark is too large, although increasing the solder mark length has a limited effect on improving the battery's internal resistance, the excessively long solder wire increases the risk of welding difficulty and defect rate. Excessively long solder wires may cause problems such as solder wire misalignment and weak welding during welding, thereby reducing welding reliability, increasing the welding defect rate, and ultimately affecting the quality and performance of the battery.
[0050] Furthermore, the second weld mark 600 includes three parallel and equally spaced negative electrode welding lines 601. If the width W20 of the second weld mark 600 is too small, the weld mark width will be too narrow, leading to excessive concentration of the negative electrode welding lines 601. During the welding process, heat will accumulate in the concentrated area of the welding lines, easily causing welding defects such as burn-through and explosion, thus increasing the welding defect rate. If the width W20 of the second weld mark 600 is too large, the weld mark width will be too wide, resulting in a greater distance between the negative electrode welding lines 601. During the welding process, the laser needs to weld the welding lines one by one. Due to the increased distance between the negative electrode welding lines 601, the laser travel will also increase accordingly, leading to a decrease in welding efficiency and a reduction in production capacity. In addition, an excessively large distance between the negative electrode welding lines 601 may also affect the current distribution and heat dissipation performance inside the battery, adversely affecting the overall performance of the battery.
[0051] Specifically, in this embodiment, the length L20 of the second solder mark 600 is 4.5 mm, and the width W20 of the second solder mark 600 is 2.5 mm. Therefore, based on the length L20 and the width W20 of the second solder mark 600, the area S200 of a single second solder mark 600 is calculated to be 11.25 mm². 2 The minimum distance between two adjacent negative electrode welding wires 601 is W202 = 0.82 mm.
[0052] This embodiment controls the length and width of the second solder mark 600 to ensure that the solder wire has sufficient current carrying capacity, reduce the battery internal resistance, improve charging and discharging efficiency, extend battery life, and improve production efficiency.
[0053] In this embodiment, the width of the negative electrode bonding wire 601 is W203, and satisfies: W203 = 0.1-0.3 mm, and the minimum distance W202 between the width of the negative electrode bonding wire 601 and the two adjacent negative electrode bonding wires 601 satisfies: W203 <W202。
[0054] It should be noted that if the width W203 of the negative electrode bonding wire 601 is too small, the width of the negative electrode bonding wire will be insufficient, the current-carrying area will be greatly reduced, and the current-carrying capacity will be significantly reduced. When current flows, the resistance at the bonding wire will increase, leading to an increase in temperature, which will affect the battery's charging and discharging efficiency and performance stability, and accelerate battery aging. If the width W203 of the negative electrode bonding wire 601 is too large, although it will not further optimize the battery's internal resistance, the increased bonding area will increase the difficulty of welding. During the welding process, the energy distribution is prone to unevenness, which will reduce the reliability of welding and may lead to defects such as cold solder joints and desoldering, affecting battery quality and service life.
[0055] Specifically, in this embodiment, the width W203 of the negative electrode bonding wire 601 is 0.2 mm.
[0056] In this embodiment, the width of the negative electrode bonding wire 601 is controlled within the range of 0.1-0.3mm. If it is too small, the current-carrying area is small and the current-carrying capacity is weak, and the temperature of the bonding wire will rise, affecting the performance. If it is too large, there is no optimization of the internal resistance, and the welding reliability is reduced due to the large area. This range balances the current-carrying capacity and the welding quality, which is beneficial to the stability of battery performance.
[0057] The first solder mark 500 in this embodiment includes a positive electrode solder line 501, the width of which is W301 and satisfies: W301 = 0.2-0.4 mm.
[0058] It should be noted that if the width W301 of the positive electrode bonding wire 501 is too small, the effective welding area is insufficient, the current carrying capacity is weakened, the temperature at the bonding wire rises, and the battery performance is affected. Moreover, due to the small width of a single bonding wire, the internal resistance of the battery increases. If the width W301 of the positive electrode bonding wire 501 is too large, it not only affects the appearance, but also the energy of the bonding wire is concentrated at the bends and turns, which is prone to explosion points, changes in the color of the bonding wire, etc., and the welding defect rate increases.
[0059] Specifically, in this embodiment, the width W301 of the positive electrode bonding wire 501 is 0.3 mm;
[0060] In this embodiment, the width W301 of the positive electrode bonding wire 501 is controlled within the range of 0.2-0.4mm, achieving a balance between battery performance, appearance quality and welding quality. The reasonable bonding wire width ensures sufficient welding area and current carrying capacity, reduces battery internal resistance, and improves battery performance.
[0061] In this embodiment, both the negative electrode bonding wire 601 and the positive electrode bonding wire 501 have multiple concave portions 610 and convex portions 620. The multiple concave portions 610 and convex portions 620 are arranged alternately and continuously, and adjacent concave portions 610 and convex portions 620 are centrally rotationally symmetrical to form wavy negative electrode bonding wires 601 and positive electrode bonding wires 501. The minimum distance between the outer protruding tip of the concave portion 610 and the inner protruding tip of the convex portion 620 of the negative electrode bonding wire 601 is W201, and satisfies: W201 = 0.15-0.35mm.
[0062] It should be noted that if the minimum distance W201 between the outer protruding tip of the concave portion 610 and the inner protruding tip of the convex portion 620 of the negative electrode bonding wire 601 is too small, the bonding wires will be too close together, resulting in concentrated heat and poor heat dissipation. This heat concentration can easily lead to welding explosions, color changes, and other issues affecting battery performance and safety. Conversely, if the minimum distance W201 between the outer protruding tip of the concave portion 610 and the inner protruding tip of the convex portion 620 of the negative electrode bonding wire 601 is too large, the bonding wires will be too far apart. During welding, the laser will weld one wire at a time. Because the distance between each wire is greater, the travel distance between each wire increases, reducing welding efficiency and production capacity.
[0063] Specifically, in this embodiment, the minimum distance W201 between the outer protruding tip of the concave portion 610 and the inner protruding tip of the convex portion 620 of the negative electrode bonding wire 601 is 0.26 mm.
[0064] In this embodiment, the minimum distance W201 between the outer protruding tip of the concave portion 610 and the inner protruding tip of the convex portion 620 of the negative electrode bonding wire 601 is controlled within a suitable range of 0.15-0.35mm. This avoids the bonding wire temperature from rising due to a reduction in the current flow area and weakening of the current flow capacity caused by excessively small distances, which would affect battery performance. It also improves the reliability and efficiency of the welding process.
[0065] In this embodiment, the concave portion 610 of the positive electrode bonding wire 501 has an angle of E, which satisfies: E = 25-65°; the convex portion 620 of the positive electrode bonding wire 501 has an angle of F, which satisfies: F = 25-65°; the concave portion 610 of the negative electrode bonding wire 601 has an angle of C, which satisfies: C = 70-120°; the convex portion 620 of the negative electrode bonding wire 601 has an angle of D, which satisfies: D = 70-120°.
[0066] It should be noted that if the angle E of the concave portion 610 or the angle F of the convex portion 620 of the positive electrode bonding wire 501 is too small, the bonding wires will be completely concentrated together. During welding, energy and heat will be highly concentrated in a local area, which will easily lead to welding defects such as explosion points and changes in the color of the bonding wires. The welding defect rate will increase significantly, and the welding strength will be reduced, affecting the reliability and stability of the battery in subsequent use. If the angle E of the concave portion 610 or the angle F of the convex portion 620 of the positive electrode bonding wire 501 is too large, the total length of the bonding wires will need to be increased. Due to the process deviation of the bonding wires themselves, after the straight-line distance between the beginning and end of the bonding wires is increased in the lateral direction, they are more likely to approach the two sides of the current collector. Due to the reasonable process deviation, the bonding wires are more likely to be welded outside the current collector, resulting in a reduction in the effective welding area, a weakening of the welding current carrying capacity, and an increase in temperature at the bonding wire, which will affect the performance of the battery.
[0067] Specifically, in this embodiment, the concave portion 610 of the positive electrode bonding wire 501 has an angle E of 41°, and the convex portion 620 of the positive electrode bonding wire 501 has an angle F of 41°.
[0068] It should be noted that if the angle C of the concave portion 610 or the angle D of the convex portion 620 of the negative electrode bonding wire 601 is too small, the distance between individual bonding wires will be too close, making it difficult to dissipate heat effectively. During the welding process, heat concentration can easily lead to welding explosions, changes in the color of the bonding wire, and other defects, reducing the welding quality. If the angle C of the concave portion 610 or the angle D of the convex portion 620 of the negative electrode bonding wire 601 is too large, the bonding wire needs to meet a certain weldable length to ensure that the weldable area of the bonding wire is sufficient. However, if the angle is too large, the straight-line distance between the beginning and end of the bonding wire will become longer within a certain length. This will cause the bonding wire to extend beyond the pad surface, resulting in partial bonding wire failure, loss of current carrying capacity, weakened current carrying capacity at the bonding wire, increased current temperature rise, and impact on battery performance.
[0069] Specifically, the angle C of the concave portion 610 of the negative electrode bonding wire 601 is equal to the angle D of the convex portion 620 of the negative electrode bonding wire 601, so C = D = 95°.
[0070] This embodiment effectively avoids excessive heat concentration and unreasonable wire layout by controlling the positive electrode bonding wire angles E and F between 25-65° and the negative electrode bonding wire angles C and D between 70-120°, thereby improving the current carrying capacity of the bonding wires, reducing the temperature at the bonding wires, and thus improving the battery's charge and discharge performance, cycle life, and safety.
[0071] In this embodiment, the first solder mark 500 is located between the middle boss 400 and the outer peripheral vent 410; there are four second solder marks 600, and the four second solder marks 600 are symmetrically distributed in a cross shape.
[0072] It should be noted that the first solder mark 500 is located between the middle boss 400 and the outer peripheral vent 410, which not only ensures effective connection with the lower end plate 4 of the cap, but also avoids interference with the boss 400 and the vent 410, making the internal structure of the battery more compact and helping to improve the energy density of the battery.
[0073] Furthermore, the four second solder marks 600 are arranged in a cross-shaped symmetrical distribution, which makes the current more evenly distributed between the negative electrode current collector 2 and the negative electrode flattened end of the core 3. During the charging and discharging process of the battery, the current can pass through each solder mark evenly, avoiding the phenomenon of heat concentration caused by excessive local current, reducing the temperature gradient inside the battery, reducing the battery performance degradation and safety hazards caused by local overheating, and improving the charging and discharging efficiency and cycle life of the battery.
[0074] In this embodiment, the radius of the lower end plate 4 of the cap is R30, and satisfies: R30 = 5.29-7.29 mm; the width of the tail body 12 is L300, and satisfies: L300 = 5-7 mm; the radius of the negative electrode current collector 4 is R20, and satisfies R20 = 8.5-10.5 mm.
[0075] Specifically, in this embodiment, the radius R20 of the negative electrode current collector 4 is 9.5mm, and the area of the negative electrode current collector S20 is calculated based on the radius of the negative electrode current collector 4.
[0076] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A cylindrical lithium-ion battery, characterized in that, It includes a positive current collector (1), a negative current collector (2), a core (3), and a cap bottom plate (4), wherein, The positive current collector (1) includes a plate body (11) and a tail body (12). The tail body (12) is connected to the lower end plate (4) of the cap through a first solder mark (500). The plate body (11) is welded to the positive flat end of the core (3). The cap lower end plate (4) is provided with a boss (400) located in the middle and an air hole (410) located on the outer periphery. The area of the cap lower end plate (4) excluding the boss (400) and the air hole (410) is S30, and the area of the first solder mark (500) is S31, and satisfies: S31 / S30=4.5-8.5%. The negative electrode current collector (2) is welded to the negative electrode flattened end of the core (3) through multiple second solder marks (600). The area of the negative electrode current collector (2) is S20, and the total area of the multiple second solder marks (600) is S2000, and satisfies: S2000 / S20 = 10%-20%.
2. The cylindrical lithium-ion battery as described in claim 1, characterized in that: The first welding mark (500) has an area S31 = 5-7 mm 2 The area of the single second welding mark (600) is S200; and the area of the single second welding mark (600) and the area of the negative current collector plate (2) satisfy: S200 / S20 = 3%-5%.
3. The cylindrical lithium-ion battery of claim 1, wherein: The height of the first solder mark (500) is W30, the length of the first solder mark (500) is L30, and the height of the first solder mark (500) satisfies: W30 = 1-2mm, and the length of the first solder mark (500) L30 satisfies: L30 = 3.5-4.5mm.
4. The cylindrical lithium-ion battery of claim 1, wherein: The length of the second solder mark (600) is L20, the width of the second solder mark (600) is W20, and the length of the second solder mark (600) satisfies: L20 = 3.5-5.5mm, and the width of the second solder mark (600) satisfies: W20 = 1.6-3.4mm.
5. The cylindrical lithium-ion battery of claim 1, wherein: The second solder mark (600) includes multiple parallel negative electrode solder lines (601), and the minimum distance between two adjacent negative electrode solder lines (601) is W202, which satisfies: W202 = 0.6-1.1 mm.
6. The cylindrical lithium-ion battery of claim 5, wherein: The first solder mark (500) includes a positive electrode solder line (501), the width of which is W301 and satisfies: W301 = 0.2-0.4 mm; the width of the negative electrode solder line (601) is W203 and satisfies: W203 = 0.1-0.3 mm.
7. The cylindrical lithium-ion battery of claim 6, wherein: Both the negative electrode bonding wire (601) and the positive electrode bonding wire (501) have multiple concave portions (610) and convex portions (620). The multiple concave portions (610) and convex portions (620) are arranged alternately and continuously, and adjacent concave portions (610) and convex portions (620) are centrally rotate symmetrical to form wavy negative electrode bonding wires (601) and positive electrode bonding wires (501). The minimum distance between the outer protruding top of the concave portion (610) and the inner protruding top of the convex portion (620) of the negative electrode bonding wire (601) is W201, and satisfies: W201 = 0.15-0.35mm.
8. The cylindrical lithium-ion battery of claim 7, wherein: The concave portion (610) of the positive electrode bonding wire (501) has an angle of E, which satisfies: E = 25-65°; the convex portion (620) of the positive electrode bonding wire (501) has an angle of F, which satisfies: F = 25-65°; the concave portion (610) of the negative electrode bonding wire (601) has an angle of C, which satisfies: C = 70-120°; the convex portion (620) of the negative electrode bonding wire (601) has an angle of D, which satisfies: D = 70-120°.
9. The cylindrical lithium-ion battery of claim 1, wherein: The first solder mark (500) is located between the central boss (400) and the outer peripheral vent (410); there are four second solder marks (600), and the four second solder marks (600) are symmetrically distributed in a cross shape.
10. The cylindrical lithium-ion battery of claim 1, wherein: The radius of the lower end plate (4) of the cap is R30, and satisfies: R30 = 5.29-7.29 mm; the width of the tail body (12) is L300, and satisfies: L300 = 5-7 mm; the radius of the negative electrode collector (2) is R20, and satisfies R20 = 8.5-10.5 mm.