A cylindrical secondary battery

Abstract

The utility model provides a kind of cylindrical secondary battery, including first current collector and second current collector, the disc surface of first current collector is equipped with several first solder mark structure, the length of first solder mark structure extension direction is 48%~62% of the disc surface radius of first current collector, the width of first solder mark structure extension direction is 20%~30% of the disc surface radius of first current collector;The disc surface of second current collector is equipped with several second solder mark structure, the length of second solder mark structure extension direction is 37%~57% of the disc surface radius of second current collector, the width of second solder mark structure extension direction is 17%~36% of the disc surface radius of second current collector.The utility model according to the size of positive and negative current collector respectively to the welding length and width of solder mark structure on it is clearly limited and designed, avoid the multiple welding problems of welding size small or too large to cause welding, so that welding length and width size reach reasonable balance, effectively improve battery performance.

Description

Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a cylindrical secondary battery. Background Technology

[0002] In current cylindrical batteries, the current collector serves to conduct electricity by connecting the positive and negative tabs of the core via laser welding. Therefore, current collectors typically have multiple sets of solder marks. Extensive research and experimentation have revealed that the size of each solder mark needs to be maintained within a reasonable range. For example, if the solder mark length is too short, it leads to higher internal resistance, potentially causing concentrated heat generation at the weld, resulting in excessive rate rise. It may also cause insufficient weld strength, weakening the current-carrying capacity of the solder wire, leading to localized heat generation in the solder area during current flow, increasing the temperature at the weld, and raising the battery's internal resistance, thus affecting battery performance. Conversely, if the solder mark length is too long, the solder wire is too long, offering no significant improvement in battery internal resistance but increasing the risk of welding defects. Furthermore, the solder wire is prone to deviating from the solderable area of ​​the current collector, reducing welding reliability, lengthening the process cycle, and increasing costs.

[0003] For example, if the weld mark width is too small, the weld lines are too concentrated, resulting in excessive heat accumulation during welding. This can easily lead to weld burn-through, cratering, and other welding defects, increasing the defect rate. It can also cause problems such as weld bursts and may result in concentrated heat generation, leading to excessive temperature rise and insufficient weld strength. On the other hand, if the weld mark width is too large, the weld lines are too far apart. During welding, the laser welds one line at a time. Due to the greater distance between each line, the travel distance between each line increases, reducing welding efficiency and production capacity. The weld lines are also more likely to deviate from the weldable area of ​​the current collector, resulting in a longer flow path, higher internal resistance, and uneven current distribution. In addition, it can also easily lead to insufficient weld strength.

[0004] Therefore, the size of the solder marks on the positive and negative current collectors needs to be designed reasonably and set within a reasonable range to ensure the normal charging and discharging capability of the cylindrical battery. This is a problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0005] In view of this, this utility model proposes a cylindrical secondary battery to solve the problem of designing the structural parameters of the bonding wires on the positive and negative current collectors to set them within a reasonable numerical range.

[0006] The technical solution of this utility model is implemented as follows: This utility model provides a cylindrical secondary battery, including a first current collector disposed at the positive terminal end of the battery; and a second current collector disposed at the negative terminal end of the battery; wherein, a plurality of first soldering structures are arranged around the center of the surface of the first current collector, the length L1 of the first soldering structure in the extension direction is 48% to 62% of the radius R1 of the surface of the first current collector, and the width W1 of the first soldering structure in the extension direction is 20% to 30% of the radius R1 of the surface of the first current collector; a plurality of second soldering structures are arranged around the center of the surface of the second current collector, the length L2 of the second soldering structure in the extension direction is 37% to 57% of the radius R2 of the surface of the second current collector, and the width W2 of the second soldering structure in the extension direction is 17% to 36% of the radius R2 of the surface of the second current collector.

[0007] Based on the above technical solutions, preferably, the length L1 of the first solder mark structure in the extension direction is 4mm to 6mm, and the width W1 of the first solder mark structure in the extension direction is 2mm to 3mm.

[0008] Based on the above technical solutions, preferably, the length L2 of the second solder mark structure in the extension direction is 3.5mm to 5.5mm, and the width W2 of the second solder mark structure in the extension direction is 1.6mm to 3.4mm.

[0009] Based on the above technical solutions, preferably, the first solder mark structure includes a plurality of first solder lines, which are arranged in parallel along the width W1 direction of the first solder mark structure; the second solder mark structure includes a plurality of second solder lines, which are arranged in parallel along the width W1 direction of the second solder mark structure; both the first solder lines and the second solder lines are wavy or threaded.

[0010] More preferably, the width W in the first bonding wire extension direction 11 The thickness is 0.4mm to 0.6mm.

[0011] More preferably, a first gap is formed between two adjacent first weld lines, and the width of the first gap is W. 12 The thickness is 0.3mm to 0.5mm.

[0012] More preferably, the line width W of the second bonding wire 21 The thickness is 0.1mm to 0.3mm.

[0013] More preferably, the width of the second bonding wire in the extension direction is the same as the line width W of the second bonding wire. 21 The difference is the second gap, and the width W of the second gap is... 22 The spacing is 0.15mm to 0.35mm; the distance between two adjacent second weld lines and the width W of the second gap are... 22 The sum of these is the third gap, and the width W of the third gap is...23 The thickness ranges from 0.6mm to 1.1mm.

[0014] More preferably, the first bonding line is wavy, and the first bonding line includes a plurality of first wave units and a plurality of second wave units. The plurality of first wave units and the plurality of second wave units are respectively arranged on both sides of the extension direction of the first bonding line and connected end to end to form the first bonding line; the second bonding line is wavy, and the second bonding line includes a plurality of third wave units and a plurality of fourth wave units. The plurality of third wave units and the plurality of fourth wave units are respectively arranged on both sides of the extension direction of the second bonding line and connected end to end to form the second bonding line.

[0015] More preferably, the included angle b of the tangents at both ends of the first wave unit is 50° to 75°, the included angle a of the tangents at both ends of the second wave unit is 50° to 75°, the included angle c of the tangents at both ends of the third wave unit is 70° to 120°, and the included angle d of the tangents at both ends of the fourth wave unit is 70° to 120°.

[0016] The cylindrical secondary battery of this invention has the following advantages over the prior art:

[0017] (1) This utility model clearly defines and designs the length and width of the solder lines of the soldering structure on the positive and negative current collectors according to their dimensions, so as to avoid the problems of insufficient effective welding area, weakened battery current carrying capacity and increased battery internal resistance caused by small solder line size, and also to avoid the problems of energy concentration at the turning point of the solder line, explosion point at the welding part and increased welding defect rate caused by excessively large solder line size, so as to achieve a reasonable balance between the length and width of the solder line and effectively improve battery performance.

[0018] (2) This utility model avoids weld line deviation, burst points and local temperature rise by precisely controlling the distance between the soldering structure and the key structure, thereby improving the welding strength and heat dissipation efficiency. Attached Figure Description

[0019] 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.

[0020] Figure 1 This is a top view of the first collector plate of this utility model;

[0021] Figure 2 This is a top view of the second collector disk of this utility model;

[0022] Figure 3This is a schematic diagram of the first solder mark structure of this utility model;

[0023] Figure 4 This is a schematic diagram of the second solder mark structure of this utility model;

[0024] Figure 5 This is a schematic diagram of the structure of the first bonding wire of this utility model;

[0025] Figure 6 This is a schematic diagram of the structure of the second welding wire of this utility model.

[0026] In the diagram: 1. First collector plate; 2. First solder mark structure; 21. First solder line; 211. First wave unit; 212. Second wave unit; 201. First gap; 3. Second collector plate; 4. Second solder mark structure; 41. Second solder line; 411. Third wave unit; 412. Fourth wave unit; 401. Second gap; 402. Third gap. Detailed Implementation

[0027] 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.

[0028] like Figure 1 As shown, combined with Figure 2 The present invention relates to a cylindrical secondary battery, comprising a cylindrical shell, a cylindrical core, upper and lower end caps, a first current collector 1 and a second current collector 3.

[0029] The cylindrical shell serves as the outer casing of the cylindrical secondary battery. The core is wound into a cylindrical shape and placed inside the cylindrical shell. After the core is flattened, it has tabs at its top and bottom ends. The positive and negative tabs are welded to the first current collector 1 and the second current collector 3 respectively by laser welding electrodes. The upper and lower end covers are respectively placed on both ends of the cylindrical shell, and each end cover has a terminal post. The terminal post is laser welded to the surface of the current collector. Thus, the cylindrical secondary battery of this embodiment is formed. The cylindrical secondary battery here is a lithium battery.

[0030] The first current collector 1 is located at the positive terminal of the battery, therefore it is the positive current collector. A central hole is formed in the center of the first current collector 1, corresponding to the channel in the middle of the core. Several vents are formed around the central hole, primarily for venting gas generated during the cell reaction. The edge of the first current collector 1 typically has a rectangular tail, which is bent upwards before being welded to the terminal post on the top end cap. The radius R1 of the first current collector 1 ranges from 8.5 mm to 9.6 mm. Several first solder marks 2 are arranged around the center of the first current collector 1. These first solder marks 2 are typically positioned between adjacent vents, and multiple first solder marks 2 are arranged around the central hole. The length L1 of the first solder mark 2 extending in the direction of extension is 48% to 62% of the radius R1 of the first current collector 1, and the width W1 of the first solder mark 2 extending in the direction of extension is 20% to 30% of the radius R1 of the first current collector 1.

[0031] The second current collector 3 is located at the negative terminal of the battery, therefore it is also a positive current collector. A central hole is also formed in the center of the second current collector 3, corresponding to the channel in the middle of the winding core. The radius R2 of the second current collector 3 ranges from 8.5mm to 10.5mm. Several second solder marks 4 are arranged around the center of the second current collector 3. The length L2 of the second solder mark 4 extending in the direction of extension is 37%-57% of the radius R2 of the second current collector 3, and the width W2 of the second solder mark 4 extending in the direction of extension is 17%-36% of the radius R2 of the second current collector 3.

[0032] This solution, by simultaneously and rationally setting the ratio between the radii of the positive and negative current collectors and the length and width of their respective solder pads, ensures a large welding area while maintaining good current carrying capacity of the solder pads, relatively low internal resistance of the solder wires, and reasonable welding time and efficiency. This avoids increasing the welding defect rate and effectively improves the overall battery performance. If the ratio of the length and width of the solder pads to the radius of the current collectors is too small, the area of ​​the corresponding solder pads will decrease, causing an increase in the battery's internal resistance. The reduced effective area of ​​the solder wires will weaken the current carrying capacity of the corresponding solder wires, leading to an increase in temperature at the solder wires and consequently, an increase in the battery temperature, thus affecting battery performance. Conversely, if the welding ratio is too large, the excessively large welding area will result in longer solder wires. This not only does not improve the battery's internal resistance but also increases the welding time, reducing welding efficiency and increasing the risk of solder wire defects, leading to an increased welding defect rate, higher battery manufacturing costs, and decreased efficiency.

[0033] exist Figure 1In one optional embodiment shown, the length L1 of the first solder mark structure 2 extending in the direction of extension is 4mm to 6mm, and the width W1 of the first solder mark structure 2 extending in the direction of extension is 2mm to 3mm. For example, in this embodiment, the radius R1 of the first manifold 1 is 9.1mm, and the length and width of the second solder mark structure 4 are L1 = 5mm and W1 = 2.3mm, respectively. Therefore, L1 is 55% of R1 and W1 is 25% of R1, and the length and width dimensions of the first solder mark structure 1 are within a reasonable range.

[0034] exist Figure 2 In one optional embodiment shown, the length L2 of the second solder mark structure 4 extending in the direction of extension is 3.5mm to 5.5mm, and the width W2 of the second solder mark structure 4 extending in the direction of extension is 1.6mm to 3.4mm. For example, in this embodiment, the radius R2 of the second manifold 3 is 9.5mm, and the length and width of the second solder mark structure 4 are L2 = 4.5mm and W2 = 2.5mm, respectively. Therefore, L2 is 47% of R2 and W2 is 26% of R2, and the length and width dimensions of the second solder mark structure 4 are within a reasonable range.

[0035] exist Figure 3 and Figure 4 In one optional embodiment shown, the first solder mark structure 2 includes a plurality of first solder lines 21, which are arranged in parallel along the width W1 direction of the first solder mark structure 2; the second solder mark structure 4 includes a plurality of second solder lines 41, which are arranged in parallel along the width W1 direction of the second solder mark structure 4. Setting multiple solder lines in parallel in the solder mark structure design can effectively increase the number of welding points and improve welding strength, while also improving the current-carrying conductivity. Both the first solder lines 21 and the second solder lines 41 are wavy or threaded, or they can be continuous Z-shaped solder lines, or the solder lines extend in a serpentine manner.

[0036] exist Figure 3 In one alternative embodiment shown, the width W in the extension direction of the first bonding wire 21 11 The width is 0.4mm to 0.6mm. If the wavy first weld line 21 is considered as a rectangular welding area, the width W in the extension direction of the first weld line 21 is... 11 This can be considered as the width of the welding area; if the width W of the first weld line 21 is... 11 If the width is too small, the effective welding area will be insufficient, and the current carrying capacity of the welding wire will be weakened. At the same time, the temperature at the welding wire will rise, which will affect the battery performance. Moreover, because the width of a single welding wire is too small, the internal resistance of the battery will increase. If the width is too large, the welding wire will affect its appearance. Secondly, if the welding wire is too wide, the energy will be concentrated at the bends and turns of the welding wire, which will make the energy concentration points prone to explosion, resulting in problems such as changes in the color of the welding wire, and thus increasing the welding defect rate.

[0037] exist Figure 3 In one optional embodiment shown, a first gap 201 is formed between two adjacent first bonding wires 21, and the width W of the first gap 201 is... 12 The gap is 0.3mm to 0.5mm. If the wavy first weld line 21 is regarded as a rectangular welding area, the first gap 201 is actually the distance between two adjacent welding electrode areas. If the distance between adjacent first weld lines 21 is too large, the process cannot meet the requirements, and the weld line is prone to deviating from the design welding area of ​​the current collector (i.e., the layout area of ​​the first weld mark structure 2), increasing the ineffective conductive path and causing the current conduction path to become longer, as well as causing the internal resistance to be too large and the current to be uneven. In addition, it is also easy to cause insufficient welding connection strength. If the distance is too small, it will cause local over-melting due to the concentration of welding energy, which will lead to welding bursts and other problems. It may also cause the heat to be concentrated during the welding of the current collector, resulting in excessive temperature rise. In addition, it may still cause insufficient welding connection strength.

[0038] exist Figure 4 In one alternative embodiment shown, the line width W of the second bonding wire 41 21 The width W of the second bonding wire 41 is 0.1mm to 0.3mm. 21 If the line width is too small, the effective welding area will be insufficient, and the current carrying capacity of the welding wire will be weakened. At the same time, the temperature at the welding wire will rise, which will affect the battery performance. Moreover, because the line width of a single welding wire is too small, the internal resistance of the battery will increase. On the other hand, if the line width is too large, it will not only affect the appearance of the second welding wire 41, but also cause energy concentration at the bends and turns of the welding wire. This will make the energy concentration points prone to explosion, resulting in problems such as changes in the color of the welding wire, and thus increasing the welding defect rate.

[0039] exist Figure 4 In one optional embodiment shown, the width of the second bonding wire 41 in the extending direction is the same as the line width W of the second bonding wire 41. 21 The difference is the second gap 401, which can essentially be considered as the distance between the two wave crests at the same length position in two adjacent wavy second weld lines 41. It represents the distance between two solder points at the same length position on two adjacent second weld lines 41 in the second solder pattern 4. The width W of the second gap 401... 22 The spacing should be between 0.15mm and 0.35mm. If this spacing is too large, the distance between the two second welding lines 41 will be too far. Since the laser welds one line at a time during welding, a large distance between adjacent second welding lines 41 will increase the travel distance when the laser switches between welding lines, resulting in decreased welding efficiency and reduced production capacity. However, if the spacing is too small, the effective welding area will be insufficient, and the current carrying capacity of the welding lines will also be weakened. At the same time, the temperature at the welding line will rise, which will affect the battery performance and lead to an increase in the battery's internal resistance.

[0040] The spacing between two adjacent second weld lines 41 and the width W of the second gap 401 22 The sum is the third gap 402, because the second weld line 41 has a significant linewidth W. 21 The third gap 402 is essentially the distance between the inner edge of one side of a wave crest and the outer edge of the other side of a wave crest within the same second weld line 41. If the second weld line 41 is considered as a rectangular welding area, the third gap 402 represents the distance between the second weld line 41 excluding its line width W. 21 The distance that can be extended in the width direction. The width W of the third gap 402. 23 The width W of the third gap 402 is 0.6mm to 1.1mm. 23 If the width is too large, each second weld line 41 will extend excessively in the width direction, resulting in a larger travel distance for the laser when welding each weld line, which will reduce welding efficiency and production capacity. However, the width W of the third gap 402... 23 If the area is too small, the effective welding area will be insufficient, and the current carrying capacity of the welding wire will also be weakened. At the same time, the temperature at the welding wire will rise, which will affect the performance of the battery and lead to an increase in the internal resistance of the battery.

[0041] exist Figure 5 and Figure 6 In one optional embodiment shown, the first bonding wire 21 is wavy and includes a plurality of first wave units 211 and a plurality of second wave units 212. The plurality of first wave units 211 and the plurality of second wave units 212 are respectively arranged on both sides of the extension direction of the first bonding wire 21 and connected end to end to form the first bonding wire 21. The second bonding wire 41 is wavy and includes a plurality of third wave units 411 and a plurality of fourth wave units 412. The plurality of third wave units 411 and the plurality of fourth wave units 412 are respectively arranged on both sides of the extension direction of the second bonding wire 41 and connected end to end to form the second bonding wire 41. If the first bonding wire 21 or the second bonding wire 41 divides the bonding wire into two halves along its wavy extension direction, then the plurality of first wave units 211 and the plurality of second wave units 212, or the plurality of third wave units 411 and the plurality of fourth wave units 412, are respectively arranged on both sides of the central axis of the wavy extension direction of the bonding wire structure. The two sets of wave units are arranged alternately and connected end to end, thereby forming a continuous wavy bonding wire.

[0042] exist Figure 5 and Figure 6In one optional embodiment shown, the included angle b of the tangents at both ends of the first wave unit 211 is 50° to 75°, the included angle a of the tangents at both ends of the second wave unit 212 is 50° to 75°, the included angle c of the tangents at both ends of the third wave unit 411 is 70° to 120°, and the included angle d of the tangents at both ends of the fourth wave unit 412 is 70° to 120°. If the included angle of the bonding wire is too small, the continuous bonding wires will be completely concentrated together, resulting in a complete concentration of energy and heat in the bonding wires. This can easily cause spalling at the bonding wires, changes in the color of the bonding wires, and ultimately an increase in the welding defect rate. If the included angle of the welding wire is too large, the total length of the welding wire needs to be increased. Due to the process deviation of the welding wire itself, after the straight distance between the beginning and end of the welding wire in the lateral direction is increased, it is easy to approach the outer contour of the current collector plate 1. This will make it easy for the welding wire to be welded out of the outer side of the current collector plate 1, resulting in a reduction in the effective welding area of ​​the soldering structure in the first welding area 11, a weakening of the current carrying capacity of the welding part, an increase in temperature at the welding wire, and thus affecting the performance of the battery.

[0043] 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 secondary battery, characterized in that, include: The first current collector (1) is located at the positive terminal of the battery; The second collector (3) is located at the negative terminal of the battery; Among them, a plurality of first soldering structures (2) are arranged around the center on the disk surface of the first collector disk (1). The length L1 of the first soldering structure (2) in the extension direction is 48% to 62% of the disk surface radius R1 of the first collector disk (1), and the width W1 of the first soldering structure (2) in the extension direction is 20% to 30% of the disk surface radius R1 of the first collector disk (1). The second collector disk (3) has several second soldering structures (4) arranged around its center on its disk surface. The length L2 of the extension direction of the second soldering structure (4) is 37% to 57% of the disk surface radius R2 of the second collector disk (3), and the width W2 of the extension direction of the second soldering structure (4) is 17% to 36% of the disk surface radius R2 of the second collector disk (3).

2. The cylindrical secondary battery according to claim 1, characterized in that: The length L1 of the first solder mark structure (2) in the extension direction is 4mm to 6mm, and the width W1 of the first solder mark structure (2) in the extension direction is 2mm to 3mm.

3. The cylindrical secondary battery according to claim 1, characterized in that: The length L2 of the second solder mark structure (4) in the extension direction is 3.5mm to 5.5mm, and the width W2 of the second solder mark structure (4) in the extension direction is 1.6mm to 3.4mm.

4. The cylindrical secondary battery according to claim 1, characterized in that: The first solder mark structure (2) includes a plurality of first solder lines (21), which are arranged in parallel along the width W1 direction of the first solder mark structure (2); the second solder mark structure (4) includes a plurality of second solder lines (41), which are arranged in parallel along the width W1 direction of the second solder mark structure (4); both the first solder lines (21) and the second solder lines (41) are wavy or threaded.

5. A cylindrical secondary battery according to claim 4, characterized in that: The width W of the first bonding wire (21) in the extension direction 11 The thickness is 0.4mm to 0.6mm.

6. A cylindrical secondary battery according to claim 4, characterized in that: A first gap (201) is formed between two adjacent first bonding wires (21), the width of the first gap (201) being W. 12 The thickness is 0.3mm to 0.5mm.

7. A cylindrical secondary battery according to claim 4, characterized in that: The line width W of the second bonding wire (41) 21 The thickness is 0.1mm to 0.3mm.

8. A cylindrical secondary battery according to claim 7, characterized in that: The width of the second bonding wire (41) in the extension direction is the same as the line width W of the second bonding wire (41). 21 The difference is the second gap (401), and the width W of the second gap (401) is... 22 The thickness is 0.15mm to 0.35mm; The spacing between two adjacent second weld lines (41) and the width W of the second gap (401) 22 The sum of these is the third gap (402), and the width W of the third gap (402) is... 23 The thickness ranges from 0.6mm to 1.1mm.

9. A cylindrical secondary battery according to claim 4, characterized in that: The first bonding line (21) is wavy. The first bonding line (21) includes a plurality of first wave units (211) and a plurality of second wave units (212). The plurality of first wave units (211) and the plurality of second wave units (212) are respectively arranged on both sides of the extension direction of the first bonding line (21) and connected end to end to form the first bonding line (21). The second bonding line (41) is wavy. The second bonding line (41) includes a plurality of third wave units (411) and a plurality of fourth wave units (412). The plurality of third wave units (411) and the plurality of fourth wave units (412) are respectively arranged on both sides of the extension direction of the second bonding line (41) and connected end to end to form the second bonding line (41).

10. A cylindrical secondary battery according to claim 9, characterized in that: The included angle b of the tangents at both ends of the first wave unit (211) is 50°-75°, and the included angle a of the tangents at both ends of the second wave unit (212) is 50°-75°; The included angle c of the tangents at both ends of the third wave unit (411) is 70°-120°, and the included angle d of the tangents at both ends of the fourth wave unit (412) is 70°-120°.

Images