Positive collector plate and end plate welding structure and cylindrical secondary battery

Abstract

The utility model provides a welding structure of positive collector plate and end plate and cylindrical secondary battery, welding structure includes positive collector plate, cap lower end plate and bonding wire, positive collector plate is provided with the tail body, the cap lower end plate is provided with the boss in the middle and the air hole in the peripheral side, the bonding wire is wave-shaped, and the boss is provided with the air hole. The tail body is fixedly welded with the cap lower end plate through a welding wire, and one end of the tail body passes through the circle center of the cap lower end plate; the radius of the lower end plate of the cap is R0, the minimum distance between the air hole and the bonding wire is M31, and M31 / R0 is equal to 24-38%; according to the welding structure, by controlling the ratio of the minimum distance between the air hole and the welding wire to the radius of the lower end plate of the cap to be kept in a proper range, the situation that welding flux enters the air hole or the boss due to tolerance in the assembling and welding process is avoided, the effective welding area is prevented from being reduced, the overflowing capacity is improved, and the performance of the battery is effectively guaranteed.

Description

A welding structure of a positive current collector and an end plate, and a cylindrical secondary battery. Technical Field

[0001] This utility model relates to the field of lithium battery technology, and in particular to a welding structure of a positive current collector and an end plate, and a cylindrical secondary battery. Background Technology

[0002] Lithium battery welding technology mainly includes laser welding and laser soldering. Laser welding is characterized by high precision, high stability, automation and intelligence. It is suitable for welding lithium batteries of various shapes and sizes, and can ensure that the fullness of the weld and the weld line width reach the ideal state, thereby improving the quality and performance of lithium batteries. The principle of laser welding includes heat conduction welding and laser deep penetration welding. The former melts the workpiece through heat conduction, while the latter achieves deep penetration welding through a high power density laser beam.

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

[0004] Currently, in battery manufacturing, the welding quality between the positive current collector and the lower end plate directly affects the battery's current carrying capacity and safety. In existing technology, the distance between the solder mark and the vent hole on the outer side of the lower end plate is not set reasonably. If the solder mark is too close to the vent hole, part of the solder line will easily be welded into the vent hole. If the solder mark is too close to the center hole, the solder will invade the center hole, thereby reducing the current carrying capacity and affecting the battery's performance. Summary of the Invention

[0005] In view of this, this utility model proposes a welding structure for the positive current collector and the end plate, as well as a cylindrical secondary battery. By controlling the minimum distance between the pores and the welding wire to be kept within an appropriate range, the solder is prevented from entering the pores or bosses due to tolerances in the assembly welding process, thus preventing a reduction in the effective welding area, improving the current carrying capacity, and effectively ensuring the performance of the battery.

[0006] The technical solution of this utility model is implemented as follows: In the first aspect, this utility model provides a welding structure for a positive current collector and an end plate, including a positive current collector, a lower end plate of a cap, and a welding wire. The positive current collector is provided with a tail body, and the lower end plate of the cap is provided with a boss located in the middle and a vent located on the outer periphery. The welding wire is wavy, and the tail body is welded and fixed to the lower end plate of the cap through the welding wire. The radius of the lower end plate of the cap is R0, and the minimum distance between the vent and the welding wire is M31, which satisfies M31 / R0 = 24-38%.

[0007] Based on the above technical solutions, preferably, the minimum distance between the welding line and the center of the lower end plate of the cap is W21, and satisfies W21 / R0 = 25%-35%.

[0008] Based on the above technical solutions, preferably, the minimum distance from the intersection of the vertical line at the center of the tail body width and the welding line to the edge of the lower end plate of the cap is W22, and satisfies W22 / R0 = 40%-51%.

[0009] Based on the above technical solutions, preferably, the width of the tail body is L1, the minimum distance between the welding line and the left side of the tail body is L10, and L10 / L1 = 9%-24%.

[0010] Based on the above technical solutions, preferably, the minimum distance between the welding line and the right side of the tail body is L12, and satisfies L12 / L1 = 9%-24%.

[0011] Based on the above technical solutions, preferably, the height of the welding wire is W23, and satisfies R0=W21+W22+W23, the minimum distance between the pore and the welding wire is M31=1.57-2.37mm; and the radius of the lower end plate of the cap is R0=5.29-7.29mm.

[0012] Based on the above technical solutions, preferably, the minimum distance between the boss and the air hole is H1, and H1 = 2.75-3.15mm.

[0013] Based on the above technical solutions, preferably, the minimum distance between the air hole and the edge of the lower end plate of the cap is H3, and H3 = 0.59-0.99mm.

[0014] Based on the above technical solutions, preferably, the radius of the boss is R1, and R1 = 1.15-1.55mm, and the height of the vent is H2, satisfying R0 = R1 + H1 + H2 + H3.

[0015] Secondly, this utility model also provides a cylindrical secondary battery, including the aforementioned welded structure of the positive current collector and the end plate.

[0016] The welding structure of the positive current collector and end plate, and the cylindrical secondary battery of this invention have the following advantages over the prior art:

[0017] (1) By controlling the ratio between the minimum distance between the pores and the welding line and the radius of the lower end plate of the cap within the range of 24-38%, the tolerance in the assembly welding process is avoided so that the solder enters the pores or bosses, the effective welding area is reduced, the current carrying capacity is improved, and the performance of the battery is effectively guaranteed.

[0018] (2) By controlling the ratio between the minimum distance between the welding line and the axis of the lower end plate of the cap and the radius of the lower end plate of the cap to 25%-35% and the ratio between the minimum distance between the welding line and the edge of the lower end plate of the cap and the radius of the lower end plate of the cap to 40%-51%, the effective welding connection between the welding line and the positive current collector and the lower end plate of the cap is ensured, avoiding welding failure, weakening of overcurrent capacity or temperature rise, thereby improving the performance and safety of the battery;

[0019] (3) By controlling the reasonable range of the boss radius, the minimum distance between the boss and the vent, and the minimum distance between the vent and the edge, it is possible to ensure that the welding area is sufficient, the current carrying capacity of the welding line is stable, avoid the high temperature of welding from affecting the CID power-off function, and at the same time ensure that the vent exhaust is smooth to improve the thermal runaway safety, thereby achieving a comprehensive improvement in battery welding quality, electrical performance and safety reliability. Attached Figure Description

[0020] 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.

[0021] Figure 1 is a schematic diagram of the welding structure of the positive collector plate and the end plate of this utility model;

[0022] Figure 2 is a schematic diagram showing the distance markings between the welding line and the center point and edge point of the lower end plate of the cap in this utility model.

[0023] Figure 3 is a schematic diagram of the welding wire and tail body size markings of this utility model;

[0024] Figure 4 is a schematic diagram showing the distance markings between the air hole and the center point and edge point of the lower end plate of the cap in this utility model.

[0025] Figure 5 is a schematic diagram showing the connection between the positive electrode current collector and the lower end plate of the cap in the cylindrical secondary battery of this utility model. Detailed Implementation

[0026] 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.

[0027] As shown in Figure 1, in a first aspect, this utility model provides a welding structure for a positive current collector and an end plate, including a positive current collector 1, a capped lower end plate 2, and a welding wire 3. The positive current collector 1 is provided with a tail body 11, and the capped lower end plate 2 is provided with a boss 210 located in the middle and an air hole 220 located on the outer periphery. The tail body 11 is welded and fixed to the capped lower end plate 2 by the welding wire 3, and one end of the tail body 11 passes through the center of the capped lower end plate 2. The welding wire 3 is wavy, the radius of the capped lower end plate 2 is R0, and the minimum distance between the air hole 220 and the welding wire 3 is M31, which satisfies M31 / R0=24-38%.

[0028] It should be noted that the positive current collector 1 also includes a current collector plate, and the tail body 11 and the current collector plate are an integral structure. The current collector plate is welded to the lower end face of the full electrode tab, and the tail body 11 is welded and fixed to the upper tail body 11, so that electrical energy can flow to the cap. However, the welding quality of the positive current collector 1 and the lower end plate 2 of the cap directly affects the current carrying capacity and safety of the battery.

[0029] When M31 / R0 < 24%, the distance between the welding wire 3 and the pore 220 is insufficient. Due to assembly tolerances during the welding process, the welding wire 3 may partially intrude into the pore 220 area due to the accumulation of tolerances. At this time, the molten solder will penetrate into the pore 220, which will lead to a reduction in the effective welding area and failure of the pore function. The reduction in welding area directly leads to a reduction in the cross-sectional area of ​​the current transmission path, an increase in resistance and heat generation, an increase in energy loss, and an impact on battery life. When M31 / R0 > 38%, the welding wire 3 is too close to the boss 210 of the lower end plate 2 of the cap. Due to the tolerances in the assembly welding process, part of the welding wire is easily welded into the boss 210, resulting in a reduction in the effective welding area, a decrease in the current carrying capacity, and an impact on battery performance.

[0030] In this embodiment, by controlling the ratio between the minimum distance between the vent 220 and the welding line 3 and the radius of the lower end plate 2 of the cap to be kept within a reasonable range of 24-38%, the tolerance in the assembly and welding process is avoided so that the solder enters the vent 220 or the boss 210, thus preventing the effective welding area from being reduced, improving the current carrying capacity, and effectively ensuring the performance of the battery.

[0031] As shown in Figure 2, in this embodiment, the minimum distance M31 between the pore 220 and the welding line 3 is 1.57-2.37 mm; the radius R0 of the lower end plate 2 of the cap is 5.29-7.29 mm.

[0032] Specifically, in this embodiment, the minimum distance M31 between the vent 220 and the welding line 3 is 1.97 mm; the radius R0 of the lower end plate 2 of the cap is 6.29 mm, and M31 / R0 = 31.32%.

[0033] In this embodiment, the minimum distance between the welding line 3 and the center of the lower end plate 2 of the cap is W21, and W21 / R0 = 25%-35%; and the minimum distance from the intersection of the vertical line at the center of the width of the tail body 11 and the welding line 3 to the edge of the lower end plate 2 of the cap is W22, and W22 / R0 = 40%-51%.

[0034] It should be noted that when the minimum distance W21 between the bonding wire 3 and the axis of the lower end plate 2 of the cap is too small, the bonding wire is too close to the boss 210. Due to the process offset tolerance, the bonding wire is likely to approach or weld out of the tail edge, resulting in a smaller effective welding area, weakened current carrying capacity of the bonding wire, and increased temperature at the bonding wire, affecting battery performance. When the minimum distance W21 between the bonding wire 3 and the axis of the lower end plate 2 of the cap is too large, the distance between the bonding wire 3 and the center of the lower end plate 2 of the cap is too large, causing the bonding wire 3 to move down beyond the surface of the lower end plate 2 of the cap, resulting in the bonding wire 3 welding out of the surface area of ​​the lower end plate 2 of the cap, resulting in a smaller effective welding area, weakened current carrying capacity of the bonding wire, and increased temperature at the bonding wire, affecting battery performance.

[0035] When the minimum distance W22 between the welding wire 3 and the edge of the lower end plate 2 of the cap is too small, the welding wire 3 is too close to the edge of the lower end plate 2 of the cap. Due to the existence of process tolerance, the welding wire may weld out of the edge, resulting in weak welding or failure, which leads to increased contact resistance and indirectly affects the overcurrent capacity. When the minimum distance W22 between the welding wire 3 and the edge of the lower end plate 2 of the cap is too large, the distance between the welding wire 3 and the edge of the lower end plate 2 of the cap is too large, which leads to insufficient utilization of the internal space of the battery and affects the overall size and energy density of the battery.

[0036] In this embodiment, by controlling the ratio between the minimum distance between the welding wire 3 and the axis of the lower end plate 2 of the cap and the radius of the lower end plate 2 of the cap to be maintained at 25%-35%, and the ratio between the minimum distance W22 between the welding wire 3 and the edge of the lower end plate 2 of the cap and the radius of the lower end plate 2 of the cap to be maintained at 40%-51%, the effective welding connection between the welding wire and the positive current collector and the lower end plate of the cap is ensured, avoiding welding failure, weakened overcurrent capacity or increased temperature, thereby improving the performance and safety of the battery.

[0037] In this embodiment, the minimum distance between the welding line 3 and the center of the lower end plate 2 of the cap is W21, which ranges from 1.6 to 2.2 mm; the minimum distance between the welding line 3 and the edge of the lower end plate 2 of the cap is W22, which ranges from 2.59 to 3.19 mm.

[0038] Specifically, the minimum distance between the weld line 3 and the center of the lower end plate 2 of the cap is W21 = 1.8 mm, and satisfies W21 / R0 = 28.62%; the minimum distance between the weld line 3 and the edge of the lower end plate 2 of the cap is W22 = 2.99 mm, and satisfies W22 / R0 = 47.54%.

[0039] In this embodiment, the height of the bonding wire 3 is W23, and it satisfies R0 = W21 + W22 + W23.

[0040] It should be noted that, based on R0 = W21 + W22 + W23, and combining W21 / R0 = 25% - 35% and W22 / R0 = 40% - 51%, we can deduce that W23 / R0 = 14% - 35%. If the height of the bonding wire 3 is too small, it will lead to insufficient welding strength and increased contact resistance, affecting battery performance and lifespan. If the height of the bonding wire 3 is too large, it will cause solder overflow, structural stress concentration and thermal runaway risk, endangering battery safety.

[0041] Specifically, in this embodiment, the height of the bonding wire 3, W23, is 1.5 mm, and satisfies W23 / R0 = 0.24%.

[0042] As shown in Figure 3, the width of the tail body 11 in this embodiment is L1, the minimum distance between the welding line 3 and the left side of the tail body 11 is L10, and L10 / L1 = 9%-24% is satisfied; and the minimum distance between the welding line 3 and the right side of the tail body 11 is L12, and L12 / L1 = 9%-24% is satisfied.

[0043] It should be noted that when L10 or L12 is too small, the bonding wire 3 will be biased to one side. Due to the reasonable process deviation tolerance during the manufacturing process, the bonding wire 3 will be very close to the edge, which may cause the bonding wire 3 to be welded onto the side of the positive current collector 1, resulting in a smaller effective welding area, weakened current carrying capacity of the bonding wire 3, and increased temperature, affecting battery performance. When L10 or L12 is too large, the bonding wire 3 will be biased to the other side. Similarly, due to the process deviation, the bonding wire 3 may be welded onto the side of the positive current collector 1, resulting in a smaller effective welding area, weakened current carrying capacity of the bonding wire 3, and increased temperature, affecting battery performance.

[0044] In this example, the width of the tail body 11 satisfies L1 = 5-7mm; the minimum distance between the welding line 3 and the left side of the tail body 11 satisfies L10 = 0.6-1.4mm, and the minimum distance between the welding line 3 and the right side of the tail body 11 satisfies L12 = 0.6-1.4mm;

[0045] Specifically, the width of the tail body 11 is L1 = 6mm, the minimum distance between the welding line 3 and the left side of the tail body 11 is L10 = 1mm, and the minimum distance between the welding line 3 and the right side of the tail body 11 is L12 = 1mm.

[0046] In this example, the length of the bonding wire 3 is L11, and it satisfies L11 = 3.5-4.5mm, and L1 = L10 + L11 + L12; in this embodiment, L11 = 4mm.

[0047] As shown in Figure 4, in this example, the minimum distance between the boss 210 and the vent 220 is H1, and H1 = 2.75-3.15mm; the minimum distance between the vent 220 and the edge of the lower end plate 2 of the cap is H3, and H3 = 0.59-0.99mm; the radius of the boss 210 is R1, and R1 = 1.15-1.55mm; the height of the vent 220 is H2, and R0 = R1 + H1 + H2 + H3.

[0048] In this embodiment, there are multiple pores 220, which are evenly distributed in a ring along the center point of the boss 220.

[0049] It should be noted that if the radius R1 of the boss 210 is too small, it cannot accommodate a sufficiently thick bonding wire, resulting in a smaller bonding wire diameter, weakened current carrying capacity, and the bonding wire being close to the CID power-off groove. The high temperature of the welding may damage the CID structure, causing the power-off function to fail and affecting battery safety. If the radius R1 of the boss 210 is too large, it will occupy the welding area between the lower end plate 2 of the cap and the positive current collector 1, resulting in insufficient welding area, reduced current carrying capacity, and increased resistance due to the reduced welding area. The temperature of the bonding wire will also rise, affecting battery performance and lifespan.

[0050] When the minimum distance H1 between the boss 210 and the vent 220 is too small, the weldable area of ​​the lower end plate 2 of the cap and the positive current collector 1 is squeezed by the boss 210 and the vent 220, resulting in insufficient welding area. The reduced welding area leads to increased resistance, weakened current carrying capacity, and increased welding wire temperature. When the minimum distance H1 between the boss 210 and the vent 220 is too large, it affects the exhaust area of ​​the vent 220. When a thermal runaway reaction occurs inside the battery and a large amount of gas is generated, the gas cannot be discharged from the vent 220 in time, affecting the safety performance of the battery.

[0051] If the minimum distance H3 between the vent 220 and the edge of the lower end plate 2 of the cap is too small, the vent 220 will not align with the vent of the inner rubber ring, the gas will be blocked and unable to be discharged smoothly, the internal pressure will increase, and the battery safety will be affected. If the minimum distance H3 between the vent 220 and the edge of the lower end plate 2 of the cap is too large, the vent 220 will shift towards the axial center, occupying the welding area between the lower end plate 2 of the cap and the positive current collector 1. The reduction of the welding area will lead to an increase in resistance, a decrease in current carrying capacity, and an increase in the welding temperature.

[0052] This example, by controlling the radius R1 of the boss 210, the minimum distance between the boss 210 and the vent 220, and the minimum distance between the vent 220 and the edge within a reasonable range, can ensure sufficient welding area, stable current carrying capacity of the welding wire, avoid the impact of high welding temperature on the CID power-off function, and at the same time ensure smooth venting of the vent to improve thermal runaway safety, thereby achieving a comprehensive improvement in battery welding quality, electrical performance, and safety reliability.

[0053] In this example, the radius R0 of the lower end plate 2 of the cap is 5.29-7.29 mm; the radius R1 of the boss 210 is 1.15-1.55 mm.

[0054] Specifically, the minimum distance H1 between the boss 210 and the vent 220 is 2.95 mm, the minimum distance H3 between the vent 220 and the edge of the lower end plate 2 of the cap is 0.79 mm, the radius R0 of the lower end plate 2 of the cap is 6.29 mm, and the radius R1 of the boss 210 is 1.35 mm.

[0055] As shown in Figure 5, in a second aspect, this utility model also provides a cylindrical secondary battery, including the welded structure of the positive current collector and the end plate.

[0056] 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 between a positive current collector and an end plate, characterized in that, The device includes a positive current collector (1), a lower end plate (2) of the cap, and a welding wire (3). The positive current collector (1) is provided with a tail body (11), and the lower end plate (2) of the cap is provided with a boss (210) located in the middle and an air hole (220) located on the outer periphery. The welding wire (3) is wavy, and the tail body (11) is welded and fixed to the lower end plate (2) of the cap through the welding wire (3). The radius of the lower end plate (2) of the cap is R0, and the minimum distance between the air hole (220) and the welding wire (3) is M31, which satisfies M31 / R0 = 24-38%.

2. The welding structure of the positive current collector and the end plate as described in claim 1, characterized in that: The minimum distance between the weld line (3) and the center of the lower end plate (2) of the cap is W21, and W21 / R0 = 25%-35%.

3. The welding structure of the positive current collector and the end plate as described in claim 2, characterized in that: The minimum distance from the intersection of the vertical line at the center of the width of the tail body (11) and the weld line (3) to the edge of the lower end plate (2) of the cap is W22, and W22 / R0 = 40%-51% is satisfied; the height of the weld line (3) is W23, and R0 = W21 + W22 + W23 is satisfied.

4. The welding structure of the positive current collector and the end plate as described in claim 1, characterized in that: The width of the tail body (11) is L1, the minimum distance between the welding line (3) and the left side of the tail body (11) is L10, and L10 / L1 = 9%-24%.

5. The welding structure of the positive current collector and the end plate as described in claim 4, characterized in that: The minimum distance between the welding line (3) and the right side of the tail body (11) is L12, and L12 / L1 = 9% - 24%.

6. The welding structure of the positive current collector and the end plate as described in claim 1, characterized in that: The minimum distance M31 between the pore (220) and the welding line (3) is 1.57-2.37 mm; the radius R0 of the lower end plate (2) of the cap is 5.29-7.29 mm.

7. The welding structure of the positive current collector and the end plate as described in claim 1, characterized in that: The minimum distance between the boss (210) and the vent (220) is H1, and H1 = 2.75-3.15 mm.

8. The welding structure of the positive current collector and the end plate as described in claim 7, characterized in that: The minimum distance between the air hole (220) and the edge of the lower end plate (2) of the cap is H3, and H3 = 0.59-0.99 mm.

9. The welding structure of the positive current collector and the end plate as described in claim 8, characterized in that: The radius of the boss (210) is R1, and R1 = 1.15-1.55 mm. The height of the vent (220) is H2, and it satisfies R0 = R1 + H1 + H2 + H3.

10. A cylindrical secondary battery, characterized in that, The welding structure of the positive collector and the end plate as described in any one of claims 1-9.

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