A cylindrical lithium-ion battery

Abstract

The utility model provides a kind of cylindrical lithium ion battery, including positive current collector, negative current collector, roll core and lower end plate, positive current collector includes disc body and tail body;Tail body is welded with lower end plate by first weld mark, the area of lower end plate is S30, the area of first weld mark is S31, the area ratio of first weld mark and lower end plate is as follows: S31 / S30=3.2~6.4%;Disc body is welded with the positive rubbing end of roll core by multiple second weld marks, the area of the end surface of roll core is S0, the sum of the area of multiple second weld marks is S100, the area ratio of the sum of multiple second weld marks and the end surface of roll core is as follows: S100 / S0=13.3~17.7%;The cylindrical lithium ion battery can reduce battery internal resistance, enhance welding wire overcurrent capacity and control welding cost and efficiency by simultaneously reasonably setting positive electrode weld mark and negative electrode weld mark area size, so as to effectively improve battery overall performance.

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. It is cylindrical in shape. 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. The edges of the cylindrical battery tabs are equipped with insulating tape to prevent the tabs from contacting the casing wall, which could cause poor casing voltage. This ensures that the battery can charge and discharge normally and provides protection in abnormal conditions.

[0003] A cylindrical battery and an electrical device comprising the cylindrical battery are disclosed in publication number CN219717197U. The cylindrical battery includes: a housing, an electrode assembly, and a current collector; the housing includes an end wall and a side wall surrounding the end wall; the electrode assembly is sealed and installed inside the housing, and the side of the electrode assembly facing the end wall includes a tab; the current collector is disposed inside the housing and located between the electrode assembly and the end wall; the current collector and the tab are electrically connected by welding.

[0004] The design of the welding area of ​​the current collector of existing cylindrical batteries, whether at the positive or negative end, is not entirely reasonable. In particular, there is a lack of precise control over the reasonable range. Either the area is too small, which leads to increased internal resistance, weakened overcurrent, and increased temperature, thus damaging performance; or the area is too large, which has limited improvement on internal resistance but increases welding time, increases the risk of defects, increases cost and reduces efficiency, thus affecting the overall performance of the battery. Utility Model Content

[0005] In view of this, this utility model proposes a cylindrical lithium-ion battery. By simultaneously and reasonably setting the area of ​​the positive electrode soldering and the negative electrode soldering, it is possible to reduce the internal resistance of the battery, enhance the current carrying capacity of the soldering wire, and control the welding cost and efficiency, 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 positive electrode current collector, a negative electrode current collector, a core and a lower end plate, wherein the positive electrode current collector includes a disk body and a tail body;

[0007] The tail body is welded to the lower end plate through a first solder mark. The area of ​​the lower end plate is S30, the area of ​​the first solder mark is S31, and the area ratio of the first solder mark to the lower end plate is: S31 / S30 = 3.2~6.4%.

[0008] The disk body is welded to the positive flat end of the core through multiple second solder marks. The end face area of ​​the core is S0, the sum of the areas of the multiple second solder marks is S100, and the ratio of the sum of the areas of the multiple second solder marks to the end face area of ​​the core is: S100 / S0 = 13.3~17.7%.

[0009] The negative electrode current collector is welded to the negative electrode flattened end of the core through multiple third solder marks. The area of ​​the negative electrode current collector is S20, the sum of the areas of the multiple third solder marks is S2000, and the ratio of the sum of the areas of the multiple third solder marks to the area of ​​the negative electrode current collector is: S2000 / S20 = 10%~20%.

[0010] Based on the above technical solutions, preferably, the area of ​​the second weld mark is S10, and the ratio of the area of ​​the second weld mark to the end face area of ​​the core is: S10 / S0 = 3.3~4.4%; the area of ​​the first weld mark is S31 = 5~7mm. 2 The area of ​​the third solder mark is S200, and the ratio of the area of ​​the third solder mark to the area of ​​the negative electrode current collector is: S200 / S20 = 3%~5%.

[0011] Based on the above technical solutions, preferably, the length of the second solder mark is L10, and satisfies: L10 = 3.9~5.1mm, and the width of the second solder mark is W10, and satisfies: W10 = 2.4~3.2mm.

[0012] Based on the above technical solutions, preferably, the width of the first solder mark is W30, and satisfies: W30 = 1~2mm, and the length of the first solder mark is L30, and satisfies: L30 = 3.5~4.5mm.

[0013] Based on the above technical solutions, preferably, the width of the third solder mark is W20, and satisfies: W20 = 1.6~3.4mm, and the length of the third solder mark is L20, and satisfies: L20 = 3.5~5.5mm.

[0014] Based on the above technical solutions, preferably, the first solder mark includes a positive electrode solder wire, the width of which is W301, and satisfies: W301 = 0.2~0.4mm;

[0015] The third solder mark includes multiple parallel negative electrode solder lines, and the minimum distance between two adjacent negative electrode solder lines is W202, which satisfies: W202 = 0.6~1.1mm.

[0016] 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, the multiple concave portions and convex portions are arranged alternately and continuously, and adjacent concave portions and convex portions are centrally rotationally symmetrical, forming wavy negative electrode bonding wires and positive electrode bonding wires.

[0017] Based on the above technical solution, preferably, the minimum distance between the outer protruding tip of the concave portion and the inner protruding tip of the convex portion of the negative electrode bonding wire is W201, and satisfies: W201 = 0.15~0.35mm; the width of the negative electrode bonding wire is W203, and satisfies: W203 = 0.1~0.3mm, wherein W203... <W201。

[0018] 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°.

[0019] Based on the above technical solutions, preferably, the radius of the disk body is R1, and satisfies: R1 = 8.8~9.4mm; the end face radius of the core is R0, and satisfies: R0 = 9.18~11.18mm; the radius of the lower end plate 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.

[0020] The cylindrical lithium-ion battery of this invention has the following advantages over the prior art:

[0021] (1) By simultaneously and reasonably setting the area of ​​the positive electrode soldering and the negative electrode soldering, it is possible to reduce the internal resistance of the battery, enhance the current carrying capacity of the soldering wire, and control the welding cost and efficiency, thereby effectively improving the overall performance of the battery; (2) By reasonably setting the length and width of the first soldering, the second soldering and the third soldering respectively, it is possible to effectively ensure that the soldering wire has sufficient current carrying capacity, reduce the internal resistance of the battery, improve the charging and discharging efficiency, extend the battery life, and improve the production efficiency;

[0022] (3) By simultaneously and reasonably setting the positive electrode welding line angles E and F and the negative electrode welding line angles C and D, the problem of excessive heat concentration and unreasonable welding line layout can be effectively avoided, the overcurrent capacity of the welding line can be improved, the temperature at the welding line can be reduced, thereby improving the charging and discharging performance, cycle life and safety of the battery. 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 battery structure of this utility model;

[0025] Figure 2 This is a schematic diagram showing the connection between the lower end plate and the positive current collector of this utility model;

[0026] Figure 3 This is a schematic diagram showing the connection structure between the lower end plate and the tail body of this utility model.

[0027] Figure 4 This is a schematic diagram of the first solder mark of this utility model;

[0028] Figure 5 This is a schematic diagram showing the connection between the disc body and the winding core of this utility model;

[0029] Figure 6 This is a schematic diagram showing the connection structure between the disc body and the core of this utility model.

[0030] Figure 7 This is a schematic diagram of the second solder mark of this utility model;

[0031] Figure 8 This is a schematic diagram showing the connection between the negative electrode current collector and the winding core of this utility model;

[0032] Figure 9 This is a schematic diagram showing the connection structure between the negative current collector and the core of this utility model.

[0033] Figure 10 This is a schematic diagram of the third welding mark of this utility model. Detailed Implementation

[0034] 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.

[0035] like Figure 1-10As shown, a cylindrical lithium-ion battery of the present invention includes a positive electrode current collector 1, a negative electrode current collector 2, a core 3 and a lower end plate 4, wherein the positive electrode current collector 1 includes a disk body 11 and a tail body 12.

[0036] The disc body 11 is welded to the positive flat end of the core 3 by a plurality of second solder marks 600. The end face area of ​​the core 3 is S0, the sum of the areas of the plurality of second solder marks 600 is S100, and the ratio of the sum of the areas of the plurality of second solder marks 600 to the end face area of ​​the core 3 is: S100 / S0 = 13.3 to 17.7%.

[0037] The area of ​​the second weld mark 600 is S10, and the ratio of the area of ​​a single second weld mark 600 to the end face area of ​​the core 3 is: S10 / S0 = 3.3~4.4%.

[0038] In this embodiment, the length of the second solder mark 600 is L10, and satisfies: L10 = 3.9~5.1mm, and the width of the second solder mark 600 is W10, and satisfies: W10 = 2.4~3.2mm.

[0039] It should be noted that if the ratio of the sum of the areas of multiple second weld marks 600 to the end face area of ​​the core 3 exceeds a reasonable range, the excessively large welding area increases the difficulty of the welding operation, making it easy for the welding to deviate from the weldable area of ​​the current collector plate, resulting in battery scrap and increased production costs. Moreover, the welding time will increase significantly due to the excessively large area, reducing welding efficiency and affecting the overall capacity of the battery production line. Furthermore, the welding wire is prone to welding into the outer holes, causing some welding wires to be ineffective, resulting in insufficient effective welding area, overheating at the welding wire, and affecting battery performance. At the same time, the connection strength at the weld decreases, and problems such as loose electrical connections may occur during long-term use of the battery, reducing the quality and stability of the battery.

[0040] If the ratio of the sum of the areas of multiple second weld marks 600 to the end face area of ​​the core 3 is less than a reasonable range, the excessively small weld mark area will significantly reduce the effective overcurrent area and significantly increase the battery's internal resistance. This will not only increase energy loss during current transmission but also lead to concentrated heat generation at the weld joint, resulting in excessive rate-controlled temperature rise. This will seriously affect the battery's performance and safety during high-current charging and discharging, and may even cause serious problems such as battery thermal runaway. Moreover, the shortened effective length of the weld line will result in insufficient overcurrent capacity and intensified heat generation at the weld line, affecting battery performance. At the same time, the excessively small distance will cause the weld line to be overly concentrated, increasing the risk of weld bursts and resulting in insufficient weld connection strength. During battery use, problems such as electrical connection interruption or structural damage may occur, reducing the battery's reliability and service life.

[0041] In this embodiment, when the ratio of the sum of the positive electrode solder areas of the cylindrical lithium-ion battery to the end face area of ​​the core is within a reasonable range of 13.3% to 17.7%, it can provide sufficient current flow area, reduce internal resistance, control temperature rise, and ensure efficient charging and discharging of the battery. It can also ensure stable welding quality and reliable connection strength, and make welding efficient, reducing defect rate and scrap.

[0042] Specifically, in this embodiment, the end face area S0 of the core 3 is 325.41 mm². 2 The area S10 of a single second solder mark 600 is 12.60 mm². 2 The sum of the areas of the multiple second solder marks 600, S100 = 50.40 mm. 2 The ratio of the area of ​​a single second weld mark 600 to the end face area of ​​the core 3 is S10 / S0 = 3.9%, and the ratio of the sum of the areas of multiple second weld marks 600 to the end face area of ​​the core 3 is S100 / S0 = 15.5%. In this embodiment, the length of the weld mark 3 is L10 = 4.5 mm, and the width of the weld mark 3 is W10 = 2.8 mm.

[0043] The tail section 12 is welded to the lower end plate 4 via a first solder mark 500. The area of ​​the lower end plate 4 is S30, and the area of ​​the first solder mark 500 is S31. The area ratio of the first solder mark 500 to the area of ​​the lower end plate 4 is S31 / S30 = 3.2-6.4%; the area of ​​the first solder mark 500 is S31 = 5-7 mm. 2 .

[0044] It should be noted that if the area ratio of the first solder mark 500 to the lower end plate 4 is less than a reasonable range, the reduced solder mark area directly leads to an increase in the battery's internal resistance. During battery charging and discharging, the increased resistance to current flow results in increased energy loss and reduced charging and discharging efficiency. Simultaneously, the current-carrying capacity of the solder wire weakens. Under high current conditions, the solder wire cannot effectively carry the current, causing a sharp rise in solder wire temperature, which in turn raises the overall battery temperature, accelerates internal chemical reactions, shortens battery life, and severely impacts battery performance. Furthermore, an excessively small solder mark area means fewer welding contact points and insufficient welding connection strength. During battery use, when subjected to external forces such as vibration and impact, problems such as solder mark detachment and loosening are likely to occur, leading to electrical connection interruptions, preventing the battery from functioning properly, and reducing battery reliability and safety.

[0045] If the area ratio of the first weld mark 500 to the lower end plate 4 is greater than a reasonable range, the excessively large welding area will increase the difficulty of welding operations, and may easily lead to problems such as weld lines deviating from the predetermined position and uneven welding, increasing the risk of defective weld lines; in addition, the welding time will be extended accordingly as the welding area increases, reducing welding efficiency and affecting the production capacity of the battery production line.

[0046] When the ratio of the first solder area 500 to the area of ​​the lower end plate 4 is within a reasonable range of 3.2-6.4%, it can avoid the damage to performance caused by the increase in battery internal resistance, the weakening of overcurrent capacity, and the increase in solder wire and battery temperature due to the area being too small. It can also prevent the increase in solder wire defect risk, the increase in defect rate, and the extension of soldering time due to the area being too large, thereby reducing manufacturing costs and improving efficiency.

[0047] Specifically, in this embodiment, the area S30 of the lower end plate 4 is 124.23 mm². 2 The area of ​​the first solder mark 500 is S31 = 6 mm. 2 The area ratio of the first solder mark 500 to the lower end plate 4 is: S31 / S30 = 4.8%.

[0048] The negative electrode current collector 2 is welded to the negative electrode flattened end of the core 3 through multiple third solder marks 700. The area of ​​the negative electrode current collector 2 is S20, and the sum of the areas of the multiple third solder marks 700 is S2000. The ratio of the sum of the areas of the multiple third solder marks 700 to the area of ​​the negative electrode current collector 2 is: S2000 / S20 = 10%~20%; the ratio of the area of ​​a single third solder mark 700 to the area of ​​the negative electrode current collector 2 is: S200 / S20 = 3%~5%.

[0049] It should be noted that if the sum of the areas of multiple third solder marks 700 and the area of ​​the negative electrode current collector 2 is less than a reasonable range, the overcurrent capacity is significantly weakened. During battery charging and discharging, the current flow is restricted, resulting in a relative increase in the battery's internal resistance, increased energy loss, and reduced charging and discharging efficiency. At the same time, due to the concentrated current flow at the solder joint, the temperature rises sharply. Excessive temperature will accelerate the decomposition and aging of the internal chemical substances of the battery, affecting the battery's capacity, cycle life, and other performance indicators. Furthermore, the small overcurrent area increases the pressure on the solder joint to bear the current. Under long-term use, the connection between the solder joint and the negative electrode current collector, as well as the flattened end of the core negative electrode, is prone to loosening and poor soldering, leading to unstable electrical connections. During battery operation, voltage fluctuations and sudden power outages may occur, reducing the battery's reliability and safety.

[0050] If the ratio of the sum of the areas of multiple third weld marks 700 to the area of ​​the negative electrode current collector 2 exceeds a reasonable range, although the excessively large weld mark area has limited effect on improving the battery's internal resistance, it will increase the difficulty of welding. With an enlarged weld line area, problems such as weld lines deviating from their intended positions and uneven welding are more likely to occur during the welding process, leading to a decrease in welding reliability. Furthermore, the reduced distance between weld lines concentrates the heat generated during welding, making it difficult to dissipate quickly. This can easily cause defects such as weld spalls and changes in weld line color, affecting welding quality and potentially leading to serious safety issues such as battery short circuits. In addition, a larger weld area requires a longer welding time, reducing welding efficiency and impacting the overall capacity of the battery production line.

[0051] When the area ratio of the sum of the areas of multiple third solder marks 700 to the area of ​​the negative electrode current collector 2 is within a reasonable range of 10%-20%, it can avoid insufficient current flow area, weakened current flow capacity, and excessive temperature rise of the solder wire due to the small area, which would damage the battery performance and connection stability. It can also prevent defects such as reduced welding reliability and heat concentration causing explosion points due to the large area.

[0052] Specifically, the area of ​​the negative electrode current collector 2 is S20 = 283.4 mm². 2 The area of ​​a single third solder mark 700 is S200 = 11.25 mm. 2 The sum of the areas of multiple third solder marks 700, S2000 = 45mm. 2 The ratio of the sum of the areas of multiple third solder marks 700 to the area of ​​the negative current collector 2 is: S2000 / S20 = 15.9%.

[0053] In this embodiment, the width of the first solder mark 500 is W30, and satisfies: W30 = 1~2mm, and the length of the first solder mark 500 is L30, and satisfies: L30 = 3.5~4.5mm.

[0054] It should be noted that if W30 < 1mm or L30 < 3.5mm, the effective area of ​​the bonding wire is reduced. When current passes through the bonding wire, the reduced cross-sectional area leads to increased resistance and more heat generation, causing the temperature at the bonding wire to rise. High temperature can damage the internal materials and structure of the battery, affecting the battery's performance and lifespan. If W30 > 2mm or L30 > 4.5mm, the width or length of the corresponding first solder mark 500 is too large, which does not improve the battery's internal resistance. However, because the width or length of the first solder mark 500 increases, the welding time needs to be increased, the welding efficiency decreases, and the risk of welding defects increases, leading to a higher welding defect rate.

[0055] Specifically, in this embodiment, the width W30 of the first solder mark 500 is 1.5mm, and the length L30 of the first solder mark 500 is 4mm.

[0056] In this embodiment, the width of the third solder mark 700 is W20, and it satisfies: W20 = 1.6~3.4mm, and the length of the third solder mark 700 is L20, and it satisfies: L20 = 3.5~5.5mm.

[0057] It should be noted that if L20 < 3.5mm, the effective area of ​​the bonding wire is reduced. When current passes through the bonding wire, the reduced cross-sectional area leads to increased resistance and more heat generation, resulting in a rise in temperature at the bonding wire. High temperature can damage the internal materials and structure of the battery, affecting the battery's performance and lifespan.

[0058] If L20 > 5.5mm, the welding wire is too long and does not improve the internal resistance of the battery. However, the welding time needs to be increased due to the larger welding wire, the welding efficiency decreases, and the risk of welding defects increases, thus increasing the welding defect rate.

[0059] If W20 < ​​1.6mm, multiple welding lines will be welded, resulting in excessive concentration of welding lines. During the welding process, welding heat sources such as lasers act on a small area, making it difficult for heat to dissipate quickly. Heat accumulates in local areas, causing the temperature of the welding part to rise rapidly. Excessive temperature may lead to over-melting of the welding material, resulting in weld burn-through, forming explosion points and other welding defects, leading to an increase in the welding defect rate.

[0060] If W20 > ​​3.4mm, multiple welding lines are used, with a large distance between them. The laser welds one line at a time. Because the distance between each welding line increases, the laser's travel distance between each line increases, reducing overall welding efficiency. In large-scale battery production, this decrease in welding efficiency directly impacts production capacity and increases production costs.

[0061] Specifically, in this embodiment, the width W20 of the second solder mark 600 is 2.5mm; the length L20 of the second solder mark 600 is 4.5mm.

[0062] In this embodiment, the first solder mark 500 includes a positive electrode solder line 501, the width of which is W301, and satisfies: W301 = 0.2~0.4mm.

[0063] 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.

[0064] 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.

[0065] Specifically, in this embodiment, the width W301 of the positive electrode bonding wire 501 is 0.3 mm.

[0066] In this embodiment, the third solder mark 700 includes multiple parallel negative electrode solder lines 701, and the minimum distance between two adjacent negative electrode solder lines 701 is W202, which satisfies: W202 = 0.6~1.1mm.

[0067] It should be noted that the third weld mark 700 includes three parallel and equally spaced negative electrode welding lines 701. If W202 < 0.6 mm, the distance between the welding lines is very close, the heat is concentrated, the heat dissipation capacity is poor, and the welding lines are prone to problems such as welding explosion and welding line color change due to the heat concentration. If W202 > 1.1 mm, the distance between the welding lines is far. Because the distance between each line is far, the travel between each line of the laser becomes larger, the welding efficiency will decrease, and the production capacity will decrease.

[0068] Specifically, in this embodiment, the minimum distance W202 between two adjacent negative electrode bonding wires 701 is 0.82 mm.

[0069] In this embodiment, both the negative electrode bonding wire 701 and the positive electrode bonding wire 501 have multiple concave portions 710 and convex portions 720. The multiple concave portions 710 and convex portions 720 are arranged alternately and continuously, and adjacent concave portions 710 and convex portions 720 are centrally rotationally symmetrical to form wavy negative electrode bonding wires 701 and positive electrode bonding wires 501.

[0070] In this embodiment, the minimum distance between the outer protruding tip of the concave portion 710 and the inner protruding tip of the convex portion 720 of the negative electrode bonding wire 701 is W201, and satisfies: W201 = 0.15~0.35mm. The width of the negative electrode bonding wire 701 is W203, and satisfies: W203 = 0.1~0.3mm, wherein W203... <W201。

[0071] It should be noted that if the width W203 of the negative electrode bonding wire 701 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 701 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 welding reliability and may lead to defects such as poor welding and desoldering, affecting the battery quality and service life.

[0072] When the minimum distance W201 between the outer protruding tip of the concave portion 710 and the inner protruding tip of the convex portion 720 of the negative electrode bonding wire 701 is too small, the bonding wires are too close together, heat is concentrated, heat dissipation is poor, and the bonding wires are prone to welding explosions and color changes due to heat concentration, affecting the performance and safety of the battery. When the minimum distance W201 between the outer protruding tip of the concave portion 710 and the inner protruding tip of the convex portion 720 of the negative electrode bonding wire 701 is too large, the bonding wires are too far apart. During welding, the laser welds one wire at a time. Because the distance between each wire is far, the travel distance between each wire of the laser increases, welding efficiency decreases, and production capacity decreases.

[0073] Specifically, in this embodiment, the width W203 of the negative electrode bonding wire 701 is 0.2mm, and the minimum distance W201 between the outer protruding top of the concave portion 710 and the inner protruding top of the convex portion 720 of the negative electrode bonding wire 701 is 0.26mm.

[0074] In this embodiment, the minimum distance W201 between the outer protruding tip of the concave portion 710 and the inner protruding tip of the convex portion 720 of the negative electrode bonding wire 701 is controlled within a suitable range. 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 welding efficiency.

[0075] In this embodiment, the concave portion 710 of the positive electrode bonding wire 501 has an angle of E, which satisfies: E = 25~65°; the convex portion 720 of the positive electrode bonding wire 501 has an angle of F, which satisfies: F = 25~65°; the concave portion 710 of the negative electrode bonding wire 701 has an angle of C, which satisfies: C = 70~120°; the convex portion 720 of the negative electrode bonding wire 701 has an angle of D, which satisfies: D = 70~120°.

[0076] It should be noted that if the angle E of the concave portion 710 or the angle F of the convex portion 720 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 710 or the angle F of the convex portion 720 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.

[0077] Specifically, in this embodiment, the concave portion 710 of the positive electrode bonding wire 501 has an angle E of 41°, and the convex portion 720 of the positive electrode bonding wire 501 has an angle F of 41°.

[0078] It should be noted that if the angle C of the concave portion 710 or the angle D of the convex portion 720 of the negative electrode bonding wire 701 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 710 or the angle D of the convex portion 720 of the negative electrode bonding wire 701 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.

[0079] Specifically, the angle C of the concave portion 710 of the negative electrode bonding wire 701 is equal to the angle D of the convex portion 720 of the negative electrode bonding wire 701, so C = D = 95°.

[0080] 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 enhancing the charging and discharging performance and safety of the battery.

[0081] In this embodiment, the radius of the disk body 11 is R1, and satisfies: R1 = 8.8~9.4mm; the end face radius of the core 3 is R0, and satisfies: R0 = 9.18~11.18mm; the radius of the lower end plate 4 is R30, and satisfies: R30 = 5.29-7.29mm; the width of the tail body 12 is L300, and satisfies: L300 = 5~7mm; the radius of the negative electrode current collector 2 is R20, and satisfies: R20 = 8.5~10.5mm.

[0082] Specifically, in this embodiment, the radius of the disk body 11 is R1 = 9.1 mm, the radius of the lower end plate 4 is R30 = 6.29 mm, the width of the tail body 12 is L300 = 6 mm, and the radius of the negative electrode current collector 2 is R20 = 9.5 mm.

[0083] 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 lower end plate (4), wherein the positive current collector (1) includes a disk body (11) and a tail body (12); The tail body (12) is welded to the lower end plate (4) by the first solder mark (500), the area of ​​the lower end plate (4) is S30, the area of ​​the first solder mark (500) is S31, and the area ratio of the first solder mark (500) to the lower end plate (4) is: S31 / S30 = 3.2~6.4%. The disc body (11) is welded to the positive flat end of the core (3) by a plurality of second solder marks (600). The end face area of ​​the core (3) is S0, the sum of the areas of the plurality of second solder marks (600) is S100, and the ratio of the sum of the areas of the plurality of second solder marks (600) to the end face area of ​​the core (3) is: S100 / S0 = 13.3 to 17.7%. The negative electrode current collector (2) is welded to the negative electrode flattened end of the core (3) through multiple third solder marks (700). The area of ​​the negative electrode current collector (2) is S20, the sum of the areas of the multiple third solder marks (700) is S2000, and the ratio of the sum of the areas of the multiple third solder marks (700) to the area of ​​the negative electrode current collector (2) is: S2000 / S20 = 10%~20%.

2. The cylindrical lithium-ion battery as described in claim 1, characterized in that: The area of ​​the second solder mark (600) is S10, and the ratio of the area of ​​the second solder mark (600) to the end face area of ​​the core (3) is: S10 / S0 = 3.3~4.4%; the area of ​​the first solder mark (500) is S31 = 5~7mm. 2 The area of ​​the third solder mark (700) is S200, and the ratio of the area of ​​the third solder mark (700) to the area of ​​the negative current collector (2) is: S200 / S20 = 3%~5%.

3. The cylindrical lithium-ion battery as described in claim 2, characterized in that: The length of the second solder mark (600) is L10, and satisfies: L10 = 3.9~5.1mm, and the width of the second solder mark (600) is W10, and satisfies: W10 = 2.4~3.2mm.

4. The cylindrical lithium-ion battery as described in claim 3, characterized in that: The width of the first solder mark (500) is W30, and satisfies: W30 = 1~2mm, and the length of the first solder mark (500) is L30, and satisfies: L30 = 3.5~4.5mm.

5. The cylindrical lithium-ion battery as described in claim 4, characterized in that: The width of the third solder mark (700) is W20, and satisfies: W20 = 1.6~3.4mm, and the length of the third solder mark (700) is L20, and satisfies: L20 = 3.5~5.5mm.

6. The cylindrical lithium-ion battery as described in claim 1, characterized in that: The first solder mark (500) includes a positive electrode solder line (501), the width of which is W301, and satisfies: W301 = 0.2~0.4mm; The third solder mark (700) includes multiple parallel negative electrode solder lines (701), and the minimum distance between two adjacent negative electrode solder lines (701) is W202, which satisfies: W202 = 0.6~1.1mm.

7. The cylindrical lithium-ion battery as described in claim 6, characterized in that: Both the negative electrode bonding wire (701) and the positive electrode bonding wire (501) have multiple concave portions (710) and convex portions (720). The multiple concave portions (710) and convex portions (720) are arranged alternately and continuously, and adjacent concave portions (710) and convex portions (720) are centrally rotate symmetrical to form wavy negative electrode bonding wires (701) and positive electrode bonding wires (501).

8. The cylindrical lithium-ion battery as described in claim 7, characterized in that: The minimum distance between the outer protruding tip of the concave portion (710) and the inner protruding tip of the convex portion (720) of the negative electrode bonding wire (701) is W201, and satisfies: W201 = 0.15~0.35mm; the width of the negative electrode bonding wire (701) is W203, and satisfies: W203 = 0.1~0.3mm, wherein W203... <W201。 9. The cylindrical lithium-ion battery as described in claim 8, characterized in that: The concave portion (710) of the positive electrode bonding wire (501) has an angle of E, which satisfies: E = 25~65°; the convex portion (720) of the positive electrode bonding wire (501) has an angle of F, which satisfies: F = 25~65°; the concave portion (710) of the negative electrode bonding wire (701) has an angle of C, which satisfies: C = 70~120°; the convex portion (720) of the negative electrode bonding wire (701) has an angle of D, which satisfies: D = 70~120°.

10. The cylindrical lithium-ion battery as described in claim 1, characterized in that: The radius of the disk body (11) is R1, and satisfies: R1 = 8.8~9.4mm; the end face radius of the core (3) is R0, and satisfies: R0 = 9.18~11.18mm; the radius of the lower end plate (4) is R30, and satisfies: R30 = 5.29-7.29mm; the width of the tail body (12) is L300, and satisfies: L300 = 5~7mm; the radius of the negative electrode collector disk (2) is R20, and satisfies: R20 = 8.5~10.5mm.

Images