Welding structure of positive current collector plate and cylindrical secondary battery

Abstract

The utility model provides a kind of welding structure and cylindrical secondary battery of positive current collecting disc, welding structure is used to weld the positive current collecting disc of cylindrical battery with the pole lug of cylindrical roll core end part, and welding structure includes multiple weld marks, the length of each weld mark is L10, and the width of each weld mark is W10;Positive current collecting disc is equipped with disc body, and disc body is welded and fixed with the full pole lug end surface of cylindrical roll core, and the radius of disc body is R1;The length of weld mark and the radius of disc body satisfy: L10 / R1=42.9~56.0%;The width of weld mark and the radius of disc body satisfy: W10 / R1=26.4~35.2%;The welding structure passes through the length size and width size of weld mark by reasonable setting, can take into account current carrying capacity, welding quality and heat effect control, effectively promote the overcurrent efficiency of battery, welding reliability and energy density, to significantly enhance battery overall performance.

Description

Technical Field

[0001] This utility model relates to the field of cylindrical battery technology, and in particular to a welding structure of a positive electrode current collector and a cylindrical secondary 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 single-pass cylindrical battery with publication number CN220086334U includes a core, a positive current collector, a casing, and an explosion-proof valve. The positive tab of the core is connected to the positive current collector to form a core assembly. The core assembly is disposed within the casing, and the bottom of the casing along its height direction is connected to the positive current collector. The casing has a mounting groove and a first liquid injection hole, and the positive current collector has a second liquid injection hole. The mounting groove, the first liquid injection hole, and the second liquid injection hole are sequentially connected and correspond to the center hole of the core. The explosion-proof valve is disposed in the mounting groove.

[0004] The existing design of the length and width of the current collector solder pads for cylindrical batteries is not entirely reasonable. In particular, when the solder pad width is too narrow, the current carrying capacity is limited, the solder wire is prone to overheating and the risk of solder bursting is high, and the connection strength is insufficient. On the other hand, if the solder pad width is too wide, the solder wire is prone to flowing into the outer holes, reducing the effective welding area. If the solder pad length is too short, the current carrying area is insufficient and the internal resistance is increased. If it is too long, it is easy to deviate from the welding area, increasing the scrap rate and manufacturing cost, and seriously affecting the overall performance of the battery. Utility Model Content

[0005] In view of this, this utility model proposes a welding structure for a positive electrode current collector and a cylindrical secondary battery. By reasonably setting the length and width of the weld, it can take into account the current carrying capacity, welding quality and thermal effect control, effectively improve the battery's overcurrent efficiency, welding reliability and energy density, thereby significantly enhancing the overall performance of the battery.

[0006] The technical solution of this utility model is implemented as follows: Firstly, this utility model provides a welding structure for a positive current collector, used to weld the positive current collector of a cylindrical battery to the tab at the end of a cylindrical core. The welding structure includes multiple weld marks, each weld mark having a length of L10 and a width of W10.

[0007] The positive current collector is provided with a disk body, which is welded and fixed to the end face of the full-pole lug of the cylindrical core, and the radius of the disk body is R1;

[0008] The length of the solder mark and the radius of the disk body satisfy: L10 / R1 = 42.9~56.0%;

[0009] The width of the solder mark and the radius of the disk body satisfy the following condition: W10 / R1 = 26.4~35.2%.

[0010] Based on the above technical solutions, preferably, the length of the solder mark satisfies: L10 = 3.9~5.1mm.

[0011] Based on the above technical solutions, preferably, the width of the solder mark satisfies: W10 = 2.4~3.2mm.

[0012] Secondly, this utility model also provides a cylindrical secondary battery, including a welded structure of a positive electrode current collector, wherein the minimum distance between the weld and the edge of the plate is L12, and the distance between the weld and the radius of the plate satisfies: L12 / R1=8.8~15.4%.

[0013] Based on the above technical solutions, preferably, a through hole is provided in the center of the disk body, and the minimum distance between the solder mark and the edge of the through hole is L11, which satisfies the following condition with respect to the radius of the disk body: L11 / R1=7.7~14.3%.

[0014] Based on the above technical solutions, preferably, the disk body is provided with multiple vent holes located outside the through holes, and the minimum distance between the solder mark and the edge of the vent hole is W11, which satisfies the following condition with the radius of the disk body: W11 / R1 = 4.4~8.8%.

[0015] Based on the above technical solutions, preferably, the positive current collector also includes a tail body, wherein the plate body and the tail body are fixedly connected, and symmetrically arranged inner grooves are provided at the connection between the plate body and the tail body. The minimum distance between the solder mark and the edge of the inner groove is L20, and the radius of the plate body satisfies: L20 / R1=7.7~14.3%.

[0016] Based on the above technical solutions, preferably, the solder mark includes a wavy solder line with a width of W0, which satisfies: W0 = 0.2~0.4mm.

[0017] Based on the above technical solutions, preferably, the welding wire has 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 to form a wavy welding wire. The included angle of the concave portions is B, and satisfies B = 10~30°, and the included angle of the convex portions is A, and satisfies A = 10~30°.

[0018] Based on the above technical solutions, preferably, the radius of the disk body satisfies: R1 = 8.8~9.4mm.

[0019] The welding structure of the positive electrode current collector and the cylindrical secondary battery of this invention have the following advantages over the prior art:

[0020] (1) By reasonably setting the length and width of the solder mark, the current carrying capacity and welding process feasibility can be effectively balanced, the overcurrent efficiency, welding reliability, energy density and production yield of the battery can be improved, while reducing manufacturing costs and thermal runaway risk, and improving the overall performance and service life of the battery.

[0021] (2) By controlling L11 / R1 and L12 / R1 within a reasonable range, the problem of poor welding caused by solder stamp offset is effectively solved, the feasibility of the process and the reliability of welding are balanced, and the overall performance and production efficiency of the battery are improved.

[0022] (3) By controlling W11 / R1 within a reasonable range, the spacing requirements between the solder mark and the vent hole can be effectively balanced, avoiding the problem of the solder line intruding into the vent hole or the solder mark width being insufficient, thereby improving the welding quality, overcurrent capacity, safety and production efficiency of the battery.

[0023] (4) By controlling L20 / R1 within a reasonable range, the spacing requirements between the solder mark and the groove can be effectively balanced, avoiding the offset of the solder line or its intrusion into the outer hole, thereby improving the welding quality, current carrying capacity, connection strength and production efficiency of the battery, while reducing manufacturing costs and scrap rate. Attached Figure Description

[0024] 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.

[0025] Figure 1 This is a schematic diagram of the welding marks on the welding structure of the positive current collector of this utility model;

[0026] Figure 2This is a schematic diagram showing the spacing markings between the solder marks and the through hole, inner groove, and vent hole of the cylindrical secondary battery of this utility model.

[0027] Figure 3 This is a schematic diagram of the welding wire markings for the cylindrical secondary battery of this utility model. Detailed Implementation

[0028] 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.

[0029] like Figure 1 As shown, this utility model discloses a welding structure for a positive current collector, used to weld the positive current collector 1 of a cylindrical battery to the tab at the end of a cylindrical core 2. The welding structure includes multiple weld marks 3, each weld mark 3 having a length of L10 and a width of W10. The positive current collector 1 is provided with a disk body 11, which is welded and fixed to the end face of the tab of the cylindrical core 2. The radius of the disk body 11 is R1. The length of the weld mark 3 and the radius of the disk body 11 satisfy: L10 / R1 = 42.9~56.0%; the width of the weld mark 3 and the radius of the disk body 11 satisfy: W10 / R1 = 26.4~35.2%; the length of the weld mark 3 satisfies: L10 = 3.9~5.1mm; the width of the weld mark 3 satisfies: W10 = 2.4~3.2mm; and the radius of the disk body 11 satisfies: R1 = 8.8~9.4mm.

[0030] It should be noted that when L10 / R1 < 42.9%, the short solder joint length leads to a reduction in the effective current flow area, an increase in current density, and a significant increase in internal resistance. This causes concentrated heat generation at the weld joint, resulting in a temperature rise exceeding the design threshold during high-rate discharge, accelerating battery aging. Furthermore, insufficient solder joint length leads to insufficient weld penetration and width, reducing weld connection strength and making the solder joints prone to detachment under battery vibration or impact conditions. Simultaneously, localized overheating causes uneven temperature distribution within the battery pack, affecting the consistency of charge and discharge efficiency and reducing the battery pack's cycle life. When L10 / R1 > 56.0%, the solder joint length exceeds the weldable area of ​​the current collector, making it easy to deviate from the target position during welding, leading to incomplete welds or solder joint detachment. This significantly increases the battery scrap rate and also prolongs the single welding time, slows down the production cycle, reduces welding efficiency, and increases manufacturing costs.

[0031] Furthermore, when W10 / R1 < 26.4%, insufficient solder width leads to a shortened effective length of the solder wire, reduced current carrying capacity, and increased heat generation at the weld, affecting battery performance. It also results in excessively concentrated solder wires, causing concentrated heat during welding, which can easily trigger weld bursts, leading to insufficient weld strength and reduced battery reliability. Simultaneously, localized overheating increases the internal temperature gradient of the battery, affecting charge and discharge efficiency and reducing battery energy density. When W10 / R1 > 35.2%, excessively large solder width causes the solder wire to easily weld into the outer holes, rendering some solder wires ineffective, reducing the effective welding area, and increasing heat generation at the weld. It also leads to excessively wide solder wire distribution, resulting in poor weld uniformity and reduced weld strength. During battery use, solder joint failure is more likely. Excessively large solder width requires more precise welding control, increasing equipment debugging difficulty and production costs, and may also lead to an increased scrap rate due to welding deviations.

[0032] This embodiment effectively balances current carrying capacity and welding process feasibility by reasonably setting the length and width of the solder mark. It avoids insufficient current-carrying area, increased internal resistance, concentrated heat generation, and decreased connection strength caused by an excessively small solder mark, while preventing welding deviation, increased scrap rate, reduced welding efficiency, and increased ineffective welding area caused by an excessively large solder mark. This significantly improves the battery's current-carrying efficiency, welding reliability, energy density, and production yield, while reducing manufacturing costs and the risk of thermal runaway, thus improving the battery's overall performance and service life.

[0033] Specifically, in this embodiment, the length L10 of the solder mark 3 is 4.5mm, and the width W10 of the solder mark 3 is 2.8mm.

[0034] like Figure 2 As shown, in a second aspect, the present invention also provides a cylindrical secondary battery, including a welded structure of a positive electrode current collector, wherein the minimum distance between the weld mark 3 and the edge of the disk body 11 is L12, and the radius of the disk body 11 satisfies: L12 / R1=8.8~15.4%.

[0035] In this example, a through hole 100 is provided in the center of the disk body 11. The minimum distance between the solder mark 3 and the edge of the through hole 100 is L11, and it satisfies the following condition with the radius of the disk body 11: L11 / R1=7.7~14.3%.

[0036] It should be noted that when L11 / R1 < 7.7%, due to the reasonable offset of the welding equipment, the excessively small spacing will cause the welding wire to easily exceed the solderable area of ​​the disk 11, increasing the welding defect rate. In addition, the offset of the welding wire will reduce the effective welding area and decrease the tensile strength, making the solder joints prone to falling off under battery vibration or impact conditions. When L11 / R1 > 14.3%, the excessively large L11 spacing will squeeze the distance L12 between the solder mark 3 and the edge of the disk 11, resulting in L12 being too small, which will also cause the welding wire to be offset. Furthermore, the welding offset will still cause the welding wire to exceed the solderable area, which will ultimately reduce the welding connection strength and affect the battery reliability.

[0037] In addition, when L12 / R1 < 8.8%, due to the reasonable offset of the welding equipment, the welding offset is prone to cause the welding line to go beyond the edge of the disk 11, resulting in poor welding. It will also reduce the effective welding area, reduce the shear strength of the weld, and make the solder joints prone to failure during long-term use of the battery. When L12 / R1 > 15.4%, the excessively large L12 spacing will squeeze the spacing L11 between the solder mark 3 and the through hole 100, resulting in an excessively small L11 spacing. The risk of welding line offset increases, and the welding offset may still cause the welding line to go beyond the weldable area, which will ultimately reduce the welding connection strength and affect the battery performance.

[0038] This embodiment effectively solves the welding defects caused by solder mark misalignment by controlling L11 / R1 and L12 / R1 within a reasonable range, balancing process feasibility and welding reliability, and improving the overall performance and production efficiency of the battery.

[0039] Specifically, in this embodiment, the minimum distance L11 between the solder mark 3 and the edge of the through hole 100 is 0.75 mm; the minimum distance L12 between the solder mark 3 and the edge of the disk body 11 is 1.1 mm.

[0040] In this embodiment, the disk body 11 has multiple vent holes 110, which are located outside the through hole 100. The minimum distance between the solder mark 3 and the edge of the vent hole 110 is W11, and the radius of the disk body 11 satisfies: W11 / R1 = 4.4~8.8%.

[0041] It should be noted that when W11 / R1 < 4.4%, the spacing between the solder mark 3 and the vent hole 110 is insufficient. The solder wire 301 is prone to intruding into the vent hole 110 due to welding misalignment or solder flow, resulting in some solder wires 301 becoming ineffective, reducing the effective welding area, and decreasing the current carrying capacity of the weld. Furthermore, the intrusion of the solder wire 301 into the vent hole 110 will damage the integrity of the weld, leading to a decrease in the tensile strength of the weld and making the solder joint prone to breakage during battery charging and discharging. At the same time, the increase in ineffective welding area leads to an increase in local current density and aggravated solder wire heating, which may cause the risk of battery thermal runaway, affecting battery safety and lifespan. When W11 / R1 > 8.8%, the excessively large W11 spacing will compress the spacing between the solder mark 3 and the adjacent solder mark 3 or the edge of the disk 11, resulting in the solder mark 3 width W10 being too small, shortening the effective length of the solder wire, and insufficient current carrying capacity. In addition, the insufficient width of the solder mark 3 will cause the solder wire 301 to be overly concentrated, resulting in concentrated heat during welding, which is prone to welding bursts and further reduces the welding connection strength.

[0042] This embodiment effectively balances the spacing requirements between the solder mark and the vent hole by controlling W11 / R1 within a reasonable range, avoiding problems such as solder wire intrusion into the vent hole or insufficient solder mark width, thereby improving the welding quality, current carrying capacity, safety and production efficiency of the battery.

[0043] Specifically, in this embodiment, the minimum distance W11 between the solder mark 3 and the edge of the vent hole 110 is 0.6mm.

[0044] In this embodiment, the positive current collector 1 also includes a tail body 12, wherein the disk body 11 and the tail body 12 are fixedly connected, and the connection between the disk body 11 and the tail body 12 is provided with symmetrically arranged inner grooves 120. The minimum distance between the solder mark 3 and the edge of the inner groove 120 is L20, and the radius of the disk body 11 satisfies: L20 / R1=7.7~14.3%.

[0045] It should be noted that when L20 / R1 < 7.7%, due to the reasonable offset of the welding equipment, if the L20 spacing is too small, the welding wire is prone to exceed the weldable area of ​​the disk 11 due to offset, resulting in welding point failure or battery scrap, which increases the manufacturing cost of the battery. When L20 / R1 > 14.3%, the excessive L20 spacing will compress the spacing between the solder mark 3 and the vent hole 110, causing the welding wire 301 to easily invade the vent hole 110, resulting in some welding wires being ineffective, reducing the effective welding area, decreasing the current carrying capacity, increasing the internal resistance, and aggravating the heating at the welding wire, which affects the battery charging and discharging efficiency and cycle life. Furthermore, the welding wire intrusion into the outer hole will damage the integrity of the weld, resulting in a decrease in the tensile strength of the weld, and the welding point is prone to falling off or breaking during battery use.

[0046] This embodiment effectively balances the spacing requirements between the solder mark 3 and the inner groove 120 by controlling L20 / R1 within a reasonable range, avoiding problems such as solder wire misalignment or intrusion into the outer hole, thereby improving the welding quality, current carrying capacity, connection strength and production efficiency of the battery, while reducing manufacturing costs and scrap rate.

[0047] Specifically, in this embodiment, the minimum distance L20 between the solder mark 3 and the edge of the inner groove 120 is 1mm.

[0048] like Figure 3 As shown, the solder mark 3 in this embodiment includes a wavy solder line 301, and the width of the solder line 301 is W0, which satisfies: W0 = 0.2~0.4mm.

[0049] It should be noted that the multiple solder marks 3 are evenly distributed in a ring along the center point of the disk body 11, which effectively provides the connection strength of the weld.

[0050] Furthermore, when W0 < 0.2 mm, the insufficient width of the solder wire leads to a reduction in the effective conductive cross-sectional area and a decrease in current carrying capacity. During high-current charging and discharging of the battery, the temperature rise at the solder wire increases significantly, accelerating solder joint aging and affecting battery performance and lifespan. When W0 > 0.4 mm, the spacing between adjacent solder wires 301 decreases, and heat is concentrated during the welding process, which can easily lead to welding bursts, incomplete welds, or weld cracks, increasing the welding defect rate and affecting the strength and current carrying capacity of the weld at this point.

[0051] This embodiment effectively balances the current carrying capacity, welding strength and thermal stability of the welding wire by controlling the width of the welding wire 301 within a reasonable range, avoiding performance degradation and welding defects caused by welding wires that are too narrow or too wide, thereby improving the overall performance and reliability of the battery.

[0052] Specifically, in this embodiment, the width W0 of the bonding wire 301 is 0.3mm.

[0053] In this embodiment, the bonding wire 301 has multiple concave portions 310 and convex portions 320. The multiple concave portions 310 and convex portions 320 are arranged alternately and continuously, and adjacent concave portions 310 and convex portions 320 are centrally rotationally symmetrical to form a wavy bonding wire 301. The included angle of the concave portions 310 is B, and B = 10 to 30°. The included angle of the convex portions 320 is A, and A = 10 to 30°.

[0054] It should be noted that when A < 10° or B < 10°, the welding wires are too dense in local areas, and the heat cannot be dissipated in time during the welding process, resulting in a sharp increase in local temperature. This can easily cause welding bursts, incomplete welds, or weld cracks, affecting the strength of the weld and the current carrying capacity at that point. When A > 30° or B > 30°, the wavy characteristics of the welding wires are weakened, the actual welding wire length is shortened, resulting in a reduction in the effective conductive cross-sectional area, a decrease in current carrying capacity, a significant increase in overcurrent temperature rise at the welding wires, accelerated solder joint aging, and impact on battery performance and lifespan.

[0055] This embodiment controls the included angle between the concave portion 310 and the convex portion 320 of the welding wire 301 within a reasonable range, which can effectively balance the heat distribution, welding wire length and welding quality of the welding wire, and avoid welding defects and performance degradation caused by the included angle being too small or too large, thereby improving the overall performance, reliability and production efficiency of the battery.

[0056] Specifically, in this embodiment, the included angle B of the concave portion 310 is equal to the included angle A of the convex portion 320, which is 18°.

[0057] 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 welding structure for a positive current collector, used to weld the positive current collector (1) of a cylindrical battery to the tab at the end of a cylindrical core (2), characterized in that, The welding structure includes multiple weld marks (3), each weld mark (3) having a length of L10 and a width of W10; The positive current collector (1) is provided with a disk body (11), and the disk body (11) is welded and fixed to the end face of the full-pole lug of the cylindrical core (2). The radius of the disk body (11) is R1. The length of the solder mark (3) and the radius of the disk body (11) satisfy: L10 / R1 = 42.9~56.0%; The width of the solder mark (3) and the radius of the disk body (11) satisfy: W10 / R1 = 26.4~35.2%.

2. The welding structure of the positive current collector as described in claim 1, characterized in that: The length of the solder mark (3) satisfies: L10 = 3.9~5.1mm.

3. The welding structure of the positive current collector as described in claim 1, characterized in that: The width of the solder mark (3) satisfies: W10 = 2.4~3.2mm.

4. A cylindrical secondary battery, characterized in that, The welding structure of the positive current collector as described in any one of claims 1-3, wherein the minimum distance between the solder mark (3) and the edge of the disk body (11) is L12, and the radius of the disk body (11) satisfies: L12 / R1 = 8.8~15.4%.

5. The cylindrical secondary battery as described in claim 4, characterized in that: The center of the disk body (11) has a through hole (100), and the minimum distance between the solder mark (3) and the edge of the through hole (100) is L11, and the radius of the disk body (11) satisfies: L11 / R1=7.7~14.3%.

6. The cylindrical secondary battery as described in claim 5, characterized in that: The disk body (11) has multiple vent holes (110) and is located outside the through hole (100). The minimum distance between the solder mark (3) and the edge of the vent hole (110) is W11, and the radius of the disk body (11) satisfies: W11 / R1 = 4.4~8.8%.

7. The cylindrical secondary battery as described in claim 4, characterized in that: The positive current collector (1) further includes a tail body (12), wherein the disk body (11) and the tail body (12) are fixedly connected, and symmetrically arranged inner grooves (120) are provided at the connection between the disk body (11) and the tail body (12). The minimum distance between the solder mark (3) and the edge of the inner groove (120) is L20, and the radius of the disk body (11) satisfies: L20 / R1=7.7~14.3%.

8. The cylindrical secondary battery as described in claim 4, characterized in that: The solder mark (3) includes a wavy solder line (301), and the width of the solder line (301) is W0, which satisfies: W0 = 0.2~0.4mm.

9. The cylindrical secondary battery as described in claim 8, characterized in that: The welding line (301) has multiple concave portions (310) and convex portions (320). The multiple concave portions (310) and convex portions (320) are arranged alternately and continuously. Adjacent concave portions (310) and convex portions (320) are centrally rotate symmetrical to form a wavy welding line (301). The included angle of the concave portions (310) is B, and B = 10 to 30°. The included angle of the convex portions (320) is A, and A = 10 to 30°.

10. The cylindrical secondary battery as described in claim 4, characterized in that: The radius of the disk body (11) satisfies: R1 = 8.8~9.4mm.

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