Negative electrode collector plate welding assembly and cylindrical lithium ion battery

Abstract

The utility model relates to the technical field of cylindrical batteries, and provides a cathode collector plate welding assembly and a cylindrical lithium ion battery, and the cathode collector plate welding assembly comprises a cathode collector plate and a plurality of welding marks positioned on the cathode collector plate, the welding mark is used for welding and fixing the negative current collecting disc and a rolling core negative electrode side flattening layer, the welding track of the negative current collecting disc and the rolling core negative electrode side flattening layer is the welding mark, and the area, fixedly connected with the rolling core negative electrode side flattening layer through one welding mark, on the negative current collecting disc is a welding face; the area of the negative collector plate is S0, the area of each welding surface is S1, and 3% S0 < = S1 < = 5% S0. According to the utility model, the welding mark is arranged on the negative collector plate, and the area of the welding mark is limited, so that the welding reliability of the negative collector plate and the roll core can be improved, the internal resistance of the battery can be optimized, the overcurrent capacity of the welding mark is enhanced, and the overall performance of the battery is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of cylindrical battery technology, and in particular to a negative electrode current collector welding assembly and a cylindrical lithium-ion battery. Background Technology

[0002] With the continuous development of new energy technologies, batteries, as high-efficiency energy storage devices, are widely used in various portable electronic products, electric vehicles, and large-scale energy storage systems. Among them, cylindrical lithium-ion batteries have gradually become one of the mainstream products in the market due to their excellent performance and high energy density.

[0003] Welding, as a reliable connection method, can provide strong mechanical strength and enable the two welded components to conduct electricity. In the assembly process of cylindrical lithium-ion batteries, laser welding or ultrasonic welding is used to fix the negative electrode current collector to the bottom of the casing and the flattened layer on the negative electrode side of the core, which can ensure that the current is conducted between the core and the casing.

[0004] For example, the invention patent with publication number CN114597504A discloses a safety component for a low internal resistance tabless cylindrical lithium battery. It has a welding part on the negative electrode current collector to weld and fix the welding part to the electrode tab. However, the welding part accounts for a large proportion of the negative electrode current collector. During the welding process between the welding part and the electrode tab, problems such as incomplete welding and explosion points are prone to occur. This not only makes it difficult to ensure the reliability of welding, but also affects the overall performance of the battery. Utility Model Content

[0005] In view of this, the present invention proposes a negative electrode current collector welding assembly and a cylindrical lithium-ion battery, which can improve the welding reliability of the negative electrode current collector and the core, and ensure the overall performance of the battery.

[0006] The technical solution of this utility model is achieved as follows: On the one hand, this utility model provides a negative electrode current collector welding assembly, including a negative electrode current collector and a plurality of solder marks located on the negative electrode current collector;

[0007] The welding stamp is used for welding and fixing the negative electrode current collector to the negative electrode side flattening layer of the core. The welding trajectory of the negative electrode current collector and the negative electrode side flattening layer of the core is the welding stamp. The area on the negative electrode current collector that is fixedly connected to the negative electrode side flattening layer of the core through the welding stamp is the welding surface.

[0008] The area of ​​the negative electrode current collector is S0, and the area of ​​each welding surface is S1, wherein 3% S0 ≤ S1 ≤ 5% S0.

[0009] Based on the above technical solutions, preferably, the sum of the areas of the plurality of welding surfaces is S. 10 Among them, 10%S0≤S 10≤20% S0.

[0010] Based on the above technical solutions, preferably, it also includes a boss, which is fixedly disposed on the negative electrode current collector and used for welding and fixing to the bottom of the shell. The area of ​​the boss is S2, wherein 5% S0≤S2≤15% S0.

[0011] Based on the above technical solutions, preferably, the solder mark includes multiple solder lines, the solder lines are wavy, and the multiple solder lines are spaced apart;

[0012] The welding surface is rectangular, with a length of L1 and a width of W1, wherein 3.5mm ≤ L1 ≤ 5.5mm and 1.6mm ≤ W1 ≤ 3.4mm.

[0013] More preferably, both the negative electrode current collector and the boss are circular in shape;

[0014] The radius of the negative current collector is R0, and the radius of the boss is R1, wherein 8.5mm≤R0≤10.5mm, and 2mm≤R1≤4mm.

[0015] More preferably, the minimum distance between the solder mark and the periphery of the negative electrode current collector is L2, wherein 0.5mm≤L2≤1.5mm.

[0016] More preferably, the minimum distance between the solder mark and the periphery of the boss is L3, wherein 0.5mm≤L3≤1.5mm.

[0017] Based on the above technical solutions, preferably, four solder marks are provided, and the four solder marks are arranged in a circumferential array around the axis of the negative electrode current collector.

[0018] Based on the above technical solution, preferably, the minimum spacing between two adjacent bonding wires is W. 10 Where 0.6mm≤W 10 ≤1.1mm.

[0019] Secondly, this utility model provides a cylindrical lithium-ion battery, including the aforementioned negative electrode current collector welding assembly.

[0020] The negative electrode current collector welding assembly and cylindrical lithium-ion battery of this utility model have the following advantages over the prior art:

[0021] (1) By setting solder marks on the negative electrode current collector and limiting the area of ​​the solder marks, not only can the welding reliability of the negative electrode current collector and the core be improved, but also the internal resistance of the battery can be optimized, the overcurrent capacity at the solder mark can be enhanced, and the overall performance of the battery can be guaranteed.

[0022] (2) By setting up bosses, the welding quality of the negative current collector and the bottom of the shell can be improved. By restricting the specifications and position of the bosses, not only can the welding reliability of the negative current collector and the bottom of the shell be improved, but the internal resistance of the battery can also be further optimized, and the overall performance of the battery can be further improved. 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 bottom view of a negative electrode current collector welding assembly according to the present invention;

[0025] Figure 2 This is a bottom view of the welding wire near the boss in a negative electrode current collector welding assembly of this utility model;

[0026] Figure 3 This is a bottom view of the welding line away from the boss in a negative electrode current collector welding assembly of this utility model.

[0027] Among them: 1. Negative current collector; 101. Welding surface; 2. Welding mark; 21. Welding line; 3. Boss. Detailed Implementation

[0028] The technical solutions of this utility model will be clearly and completely described below with reference to specific embodiments. 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 skilled in the art without creative effort are within the scope of protection of this utility model.

[0029] Cylindrical lithium-ion batteries, also known as cylindrical lithium batteries, have advantages such as high safety, high energy density, and good charge and discharge performance, and are widely used in electric vehicles, electric two-wheelers, power tools and other fields.

[0030] The present invention relates to a cylindrical lithium-ion battery, comprising a casing, a core, and a negative electrode current collector welding assembly, wherein the negative electrode current collector welding assembly comprises a negative electrode current collector 1, a solder mark 2 and a boss 3 located on the negative electrode current collector 1.

[0031] The battery core is the core component of a battery and a key element determining its performance. It includes the positive electrode sheet, negative electrode sheet, and separator. Due to the inherent flexibility and thickness of the negative electrode sheet, wrinkles, bends, or unevenness may occur at the edges during the winding process. To ensure the overall flatness and tightness of the core, certain processes are employed to treat the edges of the negative electrode sheet, creating a flattened layer on the negative electrode side of the core.

[0032] The flattened layer on the negative electrode side of the core is located at one end of the core. The welding mark 2 is the welding trajectory between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core. The laser welding head can weld and fix the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core along the path of the welding mark 2. This not only ensures the electrical connection between the two, but also improves their mechanical stability, thereby ensuring the overall performance and safety of the battery.

[0033] Multiple solder marks 2 are provided. By increasing the number of solder marks 2, not only can the internal resistance of the battery be reduced, energy loss reduced, and the charging and discharging efficiency of the battery improved, but the connection strength between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core can also be increased, making the internal structure of the battery more stable, better resistant to external forces such as vibration and impact, reducing the risk of loosening or breakage of the connection parts, and extending the service life of the battery.

[0034] The area on the negative electrode current collector 1 that is fixedly connected to the flattened layer on the negative electrode side of the core via a solder mark 2 is the welding surface 101, such as... Figure 1 As shown, the dashed rectangle represents one of the welding surfaces 101, and the edge of welding surface 101 is almost flush with the edge of the solder mark 2. The area of ​​the negative electrode current collector 1 is S0, the area of ​​each welding surface 101 is S1, and the total area of ​​the multiple welding surfaces 101 is S. 10 .

[0035] In some embodiments, 3% S0≤S1≤5% S0, meaning the area of ​​each welding surface 101 is 3%, 4%, or 5% of the area of ​​the negative electrode current collector 1. If S1<3% S0, the area of ​​the welding surface 101 is too small, reducing the current flow area between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, weakening the current flow capacity, and causing an increase in temperature at the solder mark 2, which will affect the overall performance of the battery. If S1>5% S0, the area of ​​the welding surface 101 is too large, and the optimization effect on the battery internal resistance is not obvious. It increases the welding area between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, which reduces the welding reliability between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, affecting the firmness of their connection.

[0036] In some embodiments, 10% S0≤S 10 ≤20% S0, meaning the total area of ​​multiple welding surfaces 101 is 10%, 15%, or 20% of the area of ​​the negative electrode current collector 1, etc. If S 10If S < 10%, the area of ​​multiple welding surfaces 101 is too small, reducing the current flow area between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, weakening the current flow capacity, and causing an increase in temperature at the solder mark 2, which will affect the overall performance of the battery; if S 10 If the area of ​​multiple welding surfaces 101 is greater than 20%, the optimization effect on the internal resistance of the battery will not be obvious. This will increase the welding area between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, which will reduce the welding reliability of the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, affecting the firmness of the connection between the two. At the same time, the large area of ​​multiple welding surfaces 101 will also cause the welding heat to be concentrated, making it difficult to dissipate the welding heat, resulting in defects such as explosion points and discoloration of the welding position during the welding operation.

[0037] Preferably, the welding surface 101 is set to be rectangular, and its welding marks 2 are arranged regularly, which helps to improve the connection stability between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core.

[0038] like Figures 1-3 As shown, each solder mark 2 includes multiple solder lines 21. The solder lines 21 are wavy and are spaced apart. The wavy solder lines 21 can extend the weld length and increase the contact area between the negative electrode current collector 1 and the core negative electrode side flattening layer, thereby improving the conductivity between the negative electrode current collector 1 and the core negative electrode side flattening layer and enhancing the mechanical bonding between the negative electrode current collector 1 and the core negative electrode side flattening layer.

[0039] Preferably, three solder lines 21 are provided in each solder mark 2, and the three solder lines 21 are arranged at equal intervals.

[0040] like Figures 1-3 As shown, the length of the welding surface 101 is L1, the width of the welding surface 101 is W1, and the minimum spacing between two adjacent welding lines 21 is W. 10 .

[0041] In some embodiments, 3.5mm ≤ L1 ≤ 5.5mm. That is, the length of the welding surface 101 is 3.5mm, 4.5mm, or 5.5mm, etc. If L1 < 3.5mm, the length of the welding surface 101 is too small, the current carrying capacity of the weld is weakened, resulting in greater heat generation at the weld during current carrying, increased temperature, and increased internal resistance of the battery, affecting battery performance. If L1 > 5.5mm, the length of the welding surface 101 is too large, the welding line 21 is too long, it will not improve the internal resistance of the battery better, and will increase the risk of welding defect rate between the negative current collector 1 and the flattened layer on the negative electrode side of the core, reducing the welding reliability of the negative current collector 1 and the flattened layer on the negative electrode side of the core.

[0042] In some embodiments, 1.6mm≤W1≤3.4mm, the width of the welding surface 101 is 1.6mm, 2.5mm, or 3.4mm, etc. If W1<1.6mm, the width of the welding surface 101 is too small, the distance between two adjacent welding lines 21 is too small, the heat is concentrated during welding, which makes the welding operation prone to defects such as weld penetration and explosion, increasing the welding defect rate. When welding the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, the laser welding head needs to move along each welding line 21. If W1>3.4mm, the width of the welding surface 101 is too large, the distance between two adjacent welding lines 21 is too large, which will increase the travel of the laser welding head and reduce the welding efficiency of the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core.

[0043] In some embodiments, 0.6mm≤W 10 ≤1.1mm, meaning the minimum spacing between two adjacent solder lines 21 is 0.6mm, 0.8mm, or 1.1mm, etc. If W 10 If the weld width is less than 0.6mm, then two adjacent weld lines 21 are too close together. During welding, the heat is concentrated and difficult to dissipate, leading to defects such as spalling and discoloration at the weld location. When welding the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, the laser welding head needs to be moved along each weld line 21 separately. If W 10 If the distance is greater than 1.1mm, then the two adjacent welding lines 21 are too far apart, which will increase the travel distance of the laser welding head and reduce the welding efficiency of the negative electrode current collector 1 and the flattened layer of the core negative electrode side.

[0044] like Figure 1 As shown, it is preferable to set four weld marks 2, and arrange the four weld marks 2 in a circular array around the axis of the negative electrode current collector 1. This design makes the connection between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core more balanced and stable, and can timely disperse the stress on the negative electrode current collector 1. At the same time, the symmetry and regularity of this design can also facilitate the positioning of the laser welding head, which helps to improve the welding accuracy and consistency and improve welding efficiency. To further enhance this effect, it is preferable to make the area and shape of the four weld marks 2 the same.

[0045] The bottom of the shell is the bottom end of the shell. The boss 3 is fixedly set on the negative electrode current collector 1. After the boss 3 is welded and fixed to the bottom of the shell, not only can the mechanical fixation of the negative electrode current collector 1 and the core be realized, but also the electrical connection of the three can be realized to form the negative electrode passage of the battery. At the same time, the setting of the boss 3 can better control the flatness, thereby ensuring the welding quality between it and the bottom of the shell.

[0046] Preferably, both the boss 3 and the negative electrode current collector 1 are circular in shape and are arranged concentrically to improve the connection stability between the negative electrode current collector 1 and the housing.

[0047] like Figures 1-3As shown, the radius of the negative current collector 1 is R0, and the area of ​​the negative current collector 1 is S0 = πR0. 2 The radius of boss 3 is R1, and the area of ​​boss 3 is S2 = πR1. 2 The minimum distance between solder mark 2 and the periphery of negative electrode current collector 1 is L2, and the minimum distance between solder mark 2 and the periphery of boss 3 is L3.

[0048] In some embodiments, 5% S0 ≤ S2 ≤ 15% S0, meaning the area of ​​the protrusion 3 is 5%, 10%, or 15% of the area of ​​the negative electrode current collector 1. If S2 < 5% S0, the area of ​​the protrusion 3 is too small, failing to provide sufficient welding area for welding the protrusion 3 to the bottom of the casing. When welding the protrusion 3 to the bottom of the casing, the insufficient effective welding area weakens the current carrying capacity at the welding position, leading to increased temperature rise at the welding position and affecting the overall performance of the battery. If S2 > 15% S0, the area of ​​the protrusion 3 is too large, making it difficult to control the flatness of the protrusion 3, resulting in poor surface smoothness. When welding the protrusion 3 to the bottom of the casing, it is impossible to ensure that the protrusion 3 is completely flush with the bottom of the casing, easily leading to welding defects such as incomplete soldering and cracking, affecting the performance of the battery.

[0049] In some embodiments, 8.5mm≤R0≤10.5mm and 2mm≤R1≤4mm, that is, the radius of the negative electrode current collector 1 is 8.5mm, 9.5mm, or 10.5mm, etc., and the radius of the boss 3 is 2mm, 3mm, or 4mm, etc. If R1<2mm, the area of ​​the boss 3 is too small, which cannot provide sufficient welding area for welding the boss 3 to the bottom of the casing. When welding the boss 3 to the bottom of the casing, the effective welding area is insufficient, which will weaken the current carrying capacity at the welding position, resulting in an increase in temperature at the welding position and affecting the overall performance of the battery. If R1>4mm, the area of ​​the boss 3 is too large, and the flatness of the boss 3 is difficult to control, resulting in poor surface flatness of the boss 3. When welding the boss 3 to the bottom of the casing, it is not possible to ensure that the boss 3 is completely flat with the bottom of the casing, which can easily lead to welding defects such as cold solder joints and explosions, affecting the performance of the battery.

[0050] In some embodiments, 0.5mm ≤ L2 ≤ 1.5mm, meaning the minimum distance between the solder mark 2 and the periphery of the negative electrode current collector 1 is 0.5mm, 1mm, or 1.5mm, etc. If L2 < 0.5mm, the solder mark 2 is too close to the edge of the negative electrode current collector 1, and the weld is likely to extend beyond the edge of the negative electrode current collector 1, resulting in a reduction in the welding area between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core. This reduces the effective welding area between the two, causing an increase in the overcurrent temperature rise at the welding position between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, affecting the battery performance. If L2 > 1.5mm, the solder mark 2 is too close to the center of the negative electrode current collector 1, meaning the solder mark 2 is too close to the boss 3, and the weld is likely to extend onto the boss 3, resulting in a reduction in the welding area between the boss 3 and the bottom of the casing. This increases the temperature rise at the welding position between the boss 3 and the bottom of the casing, affecting the battery performance.

[0051] In some embodiments, 0.5mm ≤ L3 ≤ 1.5mm, meaning the minimum distance between the solder mark 2 and the periphery of the boss 3 is 0.5mm, 1mm, or 1.5mm, etc. If L3 < 0.5mm, the solder mark 2 is too close to the boss 3, and the weld is easily welded onto the boss 3, resulting in a smaller welding area between the boss 3 and the bottom of the casing, which increases the temperature rise at the welding position between the boss 3 and the bottom of the casing, affecting the battery performance. If L3 > 1.5mm, the solder mark 2 is too far from the boss 3, meaning the solder mark 2 is too close to the edge of the negative electrode current collector 1, and the weld is easily welded off the edge of the negative electrode current collector 1, resulting in a smaller welding area between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, and a smaller effective welding area between the two, which increases the overcurrent temperature rise at the welding position between the negative electrode current collector 1 and the flattened layer on the negative electrode side of the core, affecting the battery performance.

[0052] In some embodiments, four solder marks 2 are provided, with L1 = 4.5 mm, L2 = L3 = 1 mm, W1 = 2.5 mm, and S0 = 283.4 mm. 2 S1 = 11.25 mm 2 S 10 =45mm 2 S2 = 28.3 mm 2 S1 = 3.97%S0, S 10 =15.9%S0, S2=10%S0. At this time, it can not only ensure the welding reliability of the negative electrode current collector 1 and the flattened layer of the negative electrode side of the core, and the welding reliability of the boss 3 and the bottom of the shell, avoiding welding defects, but also ensure the overall performance of the battery.

[0053] The working principle of the cylindrical lithium-ion battery of this invention is as follows:

[0054] By welding the boss 3 to the bottom of the shell and welding the negative electrode current collector 1 to the flattened layer on the negative electrode side of the core, not only can the negative electrode current collector 1 and the core be fixed on the shell, but also the conduction between the core negative electrode sheet and the bottom of the shell can be achieved. By restricting the specifications of the boss 3 and the solder mark 2, not only can the welding reliability of the negative electrode current collector 1 to the flattened layer on the negative electrode side of the core and the welding reliability of the boss 3 to the bottom of the shell be guaranteed, avoiding welding defects, but also ensuring the overall performance of the battery.

[0055] 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 negative electrode current collector welding assembly, characterized in that: Includes a negative current collector (1) and multiple solder marks (2) located on the negative current collector (1); The welding mark (2) is used for welding and fixing the negative electrode current collector (1) to the flattened layer on the negative electrode side of the core. The welding trajectory of the negative electrode current collector (1) and the flattened layer on the negative electrode side of the core is the welding mark (2). The area on the negative electrode current collector (1) that is fixedly connected to the flattened layer on the negative electrode side of the core through a welding mark (2) is the welding surface (101). The area of ​​the negative electrode current collector (1) is S0, and the area of ​​each welding surface (101) is S1, wherein 3%S0≤S1≤5%S0.

2. The negative electrode current collector welding assembly as described in claim 1, characterized in that: The total area of ​​the plurality of welding surfaces (101) is S 10 Among them, 10%S0≤S 10 ≤20%S0.

3. The negative electrode current collector welding assembly as described in claim 1, characterized in that: It also includes a boss (3), which is fixedly disposed on the negative electrode current collector (1) and used to be welded to the bottom of the shell. The area of ​​the boss (3) is S2, wherein 5%S0≤S2≤15%S0.

4. The negative electrode current collector welding assembly as described in claim 1, characterized in that: The solder mark (2) includes a plurality of solder lines (21), the solder lines (21) are wavy, and the plurality of solder lines (21) are spaced apart; The welding surface (101) is rectangular, the length of the welding surface (101) is L1, and the width of the welding surface (101) is W1, wherein 3.5mm≤L1≤5.5mm and 1.6mm≤W1≤3.4mm.

5. The negative electrode current collector welding assembly as described in claim 3, characterized in that: Both the negative electrode current collector (1) and the boss (3) are circular in shape; The radius of the negative current collector (1) is R0, and the radius of the boss (3) is R1, wherein 8.5mm≤R0≤10.5mm, and 2mm≤R1≤4mm.

6. The negative electrode current collector welding assembly as described in claim 3, characterized in that: The minimum distance between the solder mark (2) and the periphery of the negative electrode current collector (1) is L2, wherein 0.5mm≤L2≤1.5mm.

7. The negative electrode current collector welding assembly as described in claim 6, characterized in that: The minimum distance between the solder mark (2) and the periphery of the boss (3) is L3, wherein 0.5mm≤L3≤1.5mm.

8. A negative electrode current collector welding assembly as described in any one of claims 1-7, characterized in that: Four solder marks (2) are provided, and the four solder marks (2) are arranged in a circumferential array around the axis of the negative electrode current collector (1).

9. The negative electrode current collector welding assembly as described in claim 4, characterized in that: The minimum spacing between two adjacent bonding wires (21) is W. 10 Where 0.6mm≤W 10 ≤1.1mm.

10. A cylindrical lithium-ion battery, characterized in that: Includes the negative electrode current collector welding assembly as described in any one of claims 1-9.

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