Cathode collector plate and cylindrical battery

Abstract

The utility model discloses a cathode current collector plate and a cylindrical battery comprising the cathode current collector plate, the cathode current collector plate comprises: a body, the outer contour of which forms a circle; the welding lug boss protrudes from the main body to one side of the negative collector plate; the welding lug boss is arranged on one side of the negative electrode bus plate, the buffer lug bosses protrude from the body to the side of the negative electrode bus plate, the welding lug boss is arranged in the center of the negative electrode bus plate, and the buffer lug bosses are arranged around the welding lug boss in the circumferential direction at intervals. According to the utility model, the negative electrode confluence plate is beneficial to guaranteeing the welding quality; when the battery falls off or vibrates, the buffering lug boss can play a buffering role; the welding lug boss and the buffer lug boss jointly ensure the overcurrent capacity; and the buffer lug boss is beneficial to welding and positioning.

Description

Technical Field

[0001] The utility model relates to a negative electrode busbar and a cylindrical battery comprising the negative electrode busbar. Background Art

[0002] The negative electrode busbar is an internal structure used in cylindrical batteries. Its main function is to connect the negative electrode tab to the bottom of the shell through welding, which plays a connection and current-passing role.

[0003] Most of the existing negative busbars of cylindrical batteries are first welded to the negative electrode tabs and then placed into the shell and welded to the bottom of the shell. This rigid connection requires high welding strength. When the battery is dropped or vibrated, the negative busbar is easily detached from the bottom of the shell, affecting the current capacity and even causing the battery cell to fail.

[0004] How to ensure the welding strength between the negative busbar and the bottom of the shell and the stable connection between the negative busbar and the bottom of the shell when the battery is dropped or vibrated becomes a challenging problem. Utility Model Content

[0005] In response to the above problems, according to the first aspect of the utility model, a negative busbar is proposed, comprising: a main body, the outer contour of which is formed in a circle; a welding protrusion protruding from the main body to one side of the negative busbar; and a plurality of buffer protrusions protruding from the main body to the one side of the negative busbar, wherein the welding protrusion is arranged in the center of the negative busbar, and the plurality of buffer protrusions are arranged circumferentially around the welding protrusion and spaced apart from each other.

[0006] Due to the provision of the welding protrusion and the buffer protrusion, the negative busbar according to the utility model has the following advantages: first, since the welding protrusion protrudes toward the bottom of the shell, compared with the flat negative busbar, the negative busbar with the welding protrusion is more easily abutted against the bottom of the shell, which is beneficial to ensuring the welding quality; second, when the battery falls or vibrates, the buffer protrusion can play a buffering role, reduce the pulling force generated between the negative electrode ear and the negative busbar, prevent the negative electrode ear from being detached from the negative busbar due to excessive pulling force, and ensure the current between the negative electrode ear and the negative busbar capacity, ensuring the service life of the cylindrical battery; third, the welding protrusion is welded to the bottom of the shell, and the buffer protrusion is abutted against the bottom of the shell, both of which can pass current, jointly ensuring the current passing capacity between the negative busbar and the bottom of the shell, and can also jointly improve the welding tension; fourth, due to the presence of the buffer protrusion, when welding between the negative busbar and the negative pole ear of the winding core, it can be easily positioned to the position where welding is required, that is, between the two buffer protrusions. In addition, due to the presence of the buffer protrusion, the welding tool can also be more easily positioned using the buffer protrusion, thereby making it easier to weld.

[0007] The negative busbar according to the present invention may have one or more of the following features.

[0008] According to one embodiment, the ratio of the protrusion height of the welding protrusion to the protrusion height of the buffer protrusion is 1.0-1.1. When the protrusion height ratio is lower than 1, the welding protrusion is suspended, which is not conducive to welding with the bottom of the shell; when the protrusion height ratio is higher than 1.1, the buffer protrusion has poor abutment contact with the shell, which is not conducive to buffering and current flow.

[0009] According to one embodiment, the protrusion height of the welding protrusion is 0.1-0.3mm, and the protrusion height of the buffer protrusion is 0.1-0.3mm. The protrusion height of the welding protrusion and the protrusion height of the buffer protrusion cannot be too small, otherwise the function of the protrusion cannot be realized; the protrusion height of the welding protrusion and the protrusion height of the buffer protrusion cannot be too large, otherwise the negative busbar is thin, the process requirements are high, and the higher the height of X1 and X2, the higher the overall height of the battery cell will be, and the battery cell height required by the customer is fixed, which will squeeze the height design space of the winding core 4.

[0010] According to one embodiment, the shape of the welding protrusion is one of the following shapes: circular, square, triangular, trapezoidal, and fan-shaped; the shapes of the multiple buffer protrusions are the same and are one of the following shapes: circular, square, triangular, trapezoidal, and fan-shaped. The same shape of the multiple buffer protrusions can help ensure symmetry, thereby making the cylindrical battery more stable.

[0011] According to one embodiment, the width of the buffer protrusion extending along the circumferential direction of the negative electrode busbar is greater than or equal to 1 mm. When the width of the buffer protrusion is less than 1 mm, the buffering effect is poor.

[0012] According to one embodiment, the ratio of the length of the buffer protrusion extending along the radius of the negative electrode busbar to the radius of the negative electrode busbar is 0.2-0.8. When the length ratio is lower than 0.2, the buffer area is insufficient and the buffer effect is poor; when the length ratio is higher than 0.8, the space structure is insufficient.

[0013] According to one embodiment, the main body, the welding protrusions and the plurality of buffer protrusions are formed in one piece, which can ensure the strength of the negative electrode busbar and has a simple process.

[0014] According to one embodiment, the shape of the welding protrusion is circular, the edge of the welding protrusion is partially connected to the body, and the ratio of the arc length of the connection part where the edge of the welding protrusion is connected to the body to the arc length of the disconnection part where the edge of the welding protrusion is disconnected from the body is 0.1-10. When the ratio is lower than 0.1, the arc length of the connection part is too short, and the welding protrusion is easy to break or deform during the preparation or assembly of the battery, which is not conducive to the welding between the welding protrusion and the bottom of the shell. When the ratio is higher than 10, the arc length of the disconnection part is too short, and the buffering effect is not obvious or cannot play a buffering role.

[0015] According to a second aspect of the utility model, a cylindrical battery is proposed, comprising: a shell, the shell comprising a cylindrical barrel and a bottom that closes one end of the barrel, and the other end of the barrel is open; a cap configured to be fixedly connected to the other end of the barrel; a winding core arranged in the shell, comprising a positive pole tab located at one end of the winding core and a negative pole tab located at the other end of the winding core; a positive busbar, one side of the positive busbar is welded to the positive pole tab of the winding core, and the other side of the positive busbar is welded to the cap; and a negative busbar is arranged between the negative pole tab of the winding core and the bottom of the shell, and is configured to be welded to the negative pole tab of the winding core and the bottom of the shell respectively, wherein the negative busbar is the above-mentioned negative busbar, the one side of the negative busbar faces the bottom of the shell, the welding protrusion is configured to be welded to the bottom of the shell, and the multiple buffer protrusions are configured to abut against the bottom of the shell.

[0016] The cylindrical battery according to the present invention has the same advantages as the negative electrode busbar according to the present invention.

[0017] The cylindrical battery according to the present invention may have one or more of the following features.

[0018] According to one embodiment, the shape of the welding protrusion is circular, and the weld mark formed by welding the welding protrusion to the bottom of the shell includes an arc-shaped weld mark segment arranged adjacent to the outer periphery of the welding protrusion and a straight weld mark segment extending along the diameter direction of the welding protrusion, and one end of the straight weld mark segment is connected to one end of the arc-shaped weld mark segment. The formed G-shaped weld mark is conducive to ensuring the welding strength.

[0019] According to one embodiment, the welding line of the negative busbar and the negative electrode tab of the winding core is located between two adjacent buffer protrusions and extends outward from the welding protrusion along the radius of the negative busbar. This design is conducive to the convenience of welding between the negative busbar and the negative electrode tab of the winding core, and is also conducive to the positioning of the welding position and the positioning of the welding tool. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments of the present invention are briefly introduced below. The drawings are only used to show some embodiments of the present invention, but not to limit all embodiments of the present invention thereto.

[0021] Figure 1 is an exploded perspective view of a cylindrical battery according to the utility model;

[0022] Figure 2 It is a bottom view of the negative busbar according to the utility model;

[0023] Figure 3 is a cross-sectional view of a negative busbar according to the utility model;

[0024] Figure 4 is a cross-sectional view of a portion of a cylindrical battery according to the utility model;

[0025] Figure 5 It is a perspective view of the winding core and the negative electrode busbar of the cylindrical battery according to the utility model.

[0026] Reference numerals list

[0027] 1 Negative busbar

[0028] 11 body

[0029] 12 Welding protrusions

[0030] 13 Buffering protrusion

[0031] 14 Welding circuit

[0032] 2 Housing

[0033] 3 Blocked

[0034] 4 cores DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the technical solution of the utility model clearer, the technical solution of the embodiment of the utility model will be clearly and completely described in combination with the drawings of the specific embodiments of the utility model. The same figure marks in the drawings represent the same parts. It should be noted that the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the described embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0036] Unless otherwise defined, the technical or scientific terms used herein shall have the usual meanings understood by persons of ordinary skill in the field to which the utility model belongs. The words "first", "second" and similar words used in the patent application specification and claims of the utility model do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0037] The present invention will be described in detail below by describing exemplary embodiments.

[0038] The cylindrical battery according to the utility model can be a lithium-ion battery or a sodium-ion battery, preferably a sodium-ion battery. Compared with lithium-ion batteries, sodium-ion batteries have the advantages of low cost and good low-temperature performance. However, factors such as the shortage of lithium resources and the price increase of upper and lower materials make the low-cost advantage of sodium ions more obvious. Due to the growing demand for energy storage, the demand for low-cost energy storage battery technology is becoming more urgent, and sodium-ion batteries have great potential.

[0039] The cylindrical battery according to the present invention may include a housing 2, a cap 3 and a winding core 4. Figure 1 As shown. The shell 2 may include a cylindrical barrel and a bottom that closes one end of the barrel, and the other end of the barrel is open. The barrel and the bottom may be formed integrally, or may be formed independently and then connected together. The inner side of the bottom of the shell 2 is, for example, a plane. The cap 3 is configured to be fixedly connected to the other end of the barrel, and together with the shell 2, forms an internal accommodation space of the cylindrical battery isolated from the outside world. The core 4 is disposed in the shell 2, specifically in the internal accommodation space formed by the shell 2 and the cap 3. The core 4 includes a main body, a positive pole tab at one end of the core 4, and a negative pole tab at the other end of the core 4. When the cylindrical battery according to the utility model is a sodium ion battery, both ends of the core 4 may be a full-pole tab structure, and the positive pole tab and the negative pole tab may be flattened to form an end face to be welded.

[0040] The cylindrical battery according to the utility model may also include a positive busbar ( Figure 1 (not shown), one side of the positive busbar can be welded to the positive pole ear of the winding core 4, specifically, it can be welded to the end face of the positive pole ear after being flattened of the winding core 4, and the other side of the positive busbar can be welded to the cap 3 to achieve electrical connection between the positive pole ear and the cap 3.

[0041] The cylindrical battery according to the utility model may also include a negative electrode busbar 1, such as Figure 1 As shown, the negative electrode busbar 1 is arranged between the negative electrode lug of the winding core 4 and the bottom of the shell 2, one side of the negative electrode busbar 1 can be welded to the negative electrode lug of the winding core 4, specifically, it can be welded to the end face of the flattened negative electrode lug of the winding core 4, and the other side of the negative electrode busbar 1 can be welded to the bottom of the shell 2 to achieve electrical connection between the negative electrode lug and the shell 2.

[0042] The negative electrode busbar 1 is formed in a circular shape, and includes a body 11 whose outer contour is formed in a circular shape, and a welding protrusion 12 and a plurality of buffer protrusions 13 protruding from the body 11 to the same side of the negative electrode busbar 1. Figure 2 As shown, the welding protrusion 12 is arranged in the center of the negative electrode busbar 1, and its shape can be one of the following shapes: circular, square, triangular, trapezoidal, sectoral, Figure 2 In the embodiment, the welding protrusion 12 is circular. A plurality of buffer protrusions 13 are arranged around the welding protrusion 12 at intervals from each other in the circumferential direction, and the number of the buffer protrusions 13 is more than 2. Figure 2 In the embodiment of the present invention, the number of the buffering protrusions 13 is 6, which are evenly spaced apart in the circumferential direction. The shapes of the plurality of buffering protrusions 13 are the same as each other, and can be one of the following shapes: circular, square, triangular, trapezoidal, sectoral, etc. Figure 2 In the embodiment, each buffer protrusion 13 is formed into a trapezoid. After the negative busbar 1 is assembled to the cylindrical battery, the welding protrusion 12 and the plurality of buffer protrusions 13 of the negative busbar 1 protrude toward the bottom of the shell 2, the welding protrusion 12 is configured to be welded to the bottom of the shell 2, and the plurality of buffer protrusions 13 are configured to abut against the bottom of the shell 2. Figure 3 Shown and Figure 4 The negative busbar 1 can first be formed into a thin sheet with uniform thickness, and then a part of its material is protruded downward by stamping or other processes to form a welding protrusion 12 and a plurality of buffer protrusions 13, that is, the body 11, the welding protrusion 12 and the plurality of buffer protrusions 13 can be formed as one body.

[0043] Due to the provision of the welding protrusion 12 and the buffering protrusion 13, the negative busbar 1 or cylindrical battery according to the utility model has the following advantages: first, since the welding protrusion 12 protrudes toward the bottom of the shell 2, compared with the flat negative busbar 1, the negative busbar 1 with the welding protrusion 12 is more likely to abut against the bottom of the shell 2, which is beneficial to ensure the welding quality; second, when the battery falls or vibrates, the buffering protrusion 13 can play a buffering role, reduce the pulling force generated between the negative electrode tab and the negative busbar 1, prevent the negative electrode tab and the negative busbar 1 from being separated due to excessive pulling force, ensure the flow capacity between the negative electrode tab and the negative busbar 1, and ensure the service life of the cylindrical battery; third, the welding protrusion 12 is welded to the bottom of the shell 2, and the buffering protrusion 13 abuts against the bottom of the shell 2, both of which can flow current, jointly ensure the flow capacity between the negative electrode busbar 1 and the bottom of the shell 2, and can also jointly improve the welding tension.

[0044] The protrusion height of the welding protrusion 12 (defined as X1) can be 0.1-0.3mm, and the protrusion height of the buffer protrusion 13 (defined as X2) can be 0.1-0.3mm. The protrusion height of the welding protrusion 12 and the protrusion height of the buffer protrusion 13 cannot be too small, otherwise the function of the protrusion cannot be realized; the protrusion height of the welding protrusion 12 and the protrusion height of the buffer protrusion 13 cannot be too large, otherwise the negative busbar 1 is thin, the process requirements are high, and the higher the height of X1 and X2, the higher the overall height of the battery cell, and the battery cell height required by the customer is fixed, which will squeeze the height design space of the winding core 4.

[0045] The ratio of the protrusion height of the welding protrusion 12 to the protrusion height of the buffer protrusion 13 (defined as the protrusion height ratio X1: X2) can be 1.0-1.1. When the protrusion height ratio is lower than 1, the welding protrusion 12 is suspended, which is not conducive to welding with the bottom of the shell 2; when the protrusion height ratio is higher than 1.1, the buffer protrusion 13 has poor contact with the shell 2, which is not conducive to buffering and current flow. Specific test experimental data are shown in Table 1.

[0046] Table 1 Battery performance test results when the protrusion height ratio X1:X2 takes different values

[0047]

[0048]

[0049] The meanings of the performance test parameters in Table 1 are as follows:

[0050] Welding tension: The welding tension between the negative busbar 1 and the shell 2 is tested with a tension device, which refers to the maximum force used to pull the welding position of the negative busbar 1 and the shell 2 apart until they are completely separated.

[0051] Drop voltage drop: After the battery is charged according to the standard charging system, the positive and negative terminals of the battery sample are freely dropped from a height of 1.5m to the cement floor twice each and observed for 1 hour. The voltage and internal resistance before and after are recorded. Drop voltage drop = before voltage - after voltage.

[0052] Drop resistance increase: After the battery is charged according to the standard charging system, the positive and negative terminals of the battery sample are freely dropped from a height of 1.5m to the cement floor twice each and observed for 1 hour. The voltage and internal resistance before and after are recorded. Drop resistance increase = resistance value after - resistance value before.

[0053] 5C charging capacity retention rate: The 5C charging test is performed at a temperature of 25±3℃. The battery cell is charged to the highest cut-off voltage at a constant current of 0.5C, left for 30 minutes, and discharged to the lowest cut-off voltage at a constant current of 0.5C. The discharged capacity is recorded as A1; the battery cell is charged to the highest cut-off voltage at a constant current of 5C, left for 30 minutes, and discharged to the lowest cut-off voltage at a constant current of 0.5C. The discharged capacity is recorded as A2; the definition of 5C charging capacity retention rate = A2 / A1. Among them, "-" indicates that the point bottom welding tension is too small and unqualified, resulting in poor contact between the winding core 4 and the shell 2, which makes it easy for the equipment program alarm to stop during the battery cell charge and discharge test, and thus the test cannot be performed.

[0054] It can be seen from Table 1 that when the protrusion height ratio X1:X2 is 1.0-1.1 (Examples 1, 2, and 3), the welding tension, drop voltage drop, drop resistance increase, and 5C charging capacity retention rate can all be maintained at the preferred level. When the protrusion height ratio X1:X2 is lower than 1 (Comparative Example 1), since the welding protrusion 12 is suspended, it is not conducive to welding with the bottom of the shell 2, and the tested welding tension and drop resistance increase cannot reach the preferred level. When the protrusion height ratio X1:X2 is higher than 1.1 (Comparative Example 2), the 5C charging capacity retention rate fails to reach the preferred level.

[0055] The width of the buffer protrusion 13 extending along the circumference of the negative busbar 1 can be greater than or equal to 1 mm. When the width of the buffer protrusion 13 is less than 1 mm, the buffering effect is poor. The ratio of the length of the buffer protrusion 13 extending along the radius of the negative busbar 1 to the radius of the negative busbar 1 (defined as the length ratio) is 0.2-0.8. When the length ratio is lower than 0.2, the buffering area is insufficient and the buffering effect is poor; when the length ratio is higher than 0.8, the spatial structure is insufficient.

[0056] The edge of the welding protrusion 12 can be partially connected to the body 11, that is, a part of the edge of the welding protrusion 12 is connected to the body 11, and the other part is disconnected from the body 11. In this way, the welding protrusion 12 can play a buffering role while being used for welding. The ratio of the arc length of the connecting part where the edge of the welding protrusion 12 is connected to the body 11 to the arc length of the disconnected part where the edge of the welding protrusion 12 is disconnected from the body 11 can be 0.1-10. When the ratio is lower than 0.1, the arc length of the connecting part is too short, and the welding protrusion 12 is easy to break or deform during the preparation or assembly process of the battery, which is not conducive to the welding between the welding protrusion 12 and the bottom of the shell 2. When the ratio is higher than 10, the arc length of the disconnected part is too short, and the buffering effect is not obvious or cannot play a buffering role.

[0057] The weld mark formed by welding the welding protrusion 12 to the bottom of the shell 2 needs to ensure the welding strength, as long as the weld mark is not overly concentrated. For example, the weld mark can be formed as two straight line segments extending in a straight line. Preferably, in the case where the shape of the welding protrusion 12 is circular, the weld mark formed by welding the welding protrusion 12 to the bottom of the shell 2 includes an arc-shaped weld mark segment arranged adjacent to the outer periphery of the welding protrusion 12 and a straight weld mark segment extending along the diameter direction of the welding protrusion 12, one end of the straight weld mark segment is connected to one end of the arc-shaped weld mark segment, and the other end of the straight weld mark segment can terminate at the center of the welding protrusion 12 or other positions to form a G-shaped weld mark, thereby ensuring the welding strength.

[0058] On the side of the negative busbar 1 facing the winding core 4, the negative busbar 1 is welded to the negative electrode tab of the winding core 4. Specifically, the negative busbar 1 can be welded to the negative electrode tab of the winding core 4 at its body 11, such as Figure 5 As shown, the negative busbar 1 can be welded to the negative electrode tab of the winding core 4 between two adjacent buffer protrusions 13 to form a welding line 14. More specifically, the welding line 14 can extend outward from the welding protrusion 12 along the radius of the negative busbar 1. Figure 5 In the embodiment, the negative busbar 1 is formed with 6 buffer protrusions 13 and 6 welding lines 14, and each welding line 14 is formed between two adjacent buffer protrusions 13. Due to the presence of the buffer protrusions 13, when welding between the negative busbar 1 and the negative pole ear of the winding core 4, it can be easily positioned to the position where welding is required, that is, between the two buffer protrusions 13. In addition, due to the presence of the buffer protrusions 13, the welding tool can also be more easily positioned by using the buffer protrusions 13, so that welding is easier.

[0059] The exemplary implementation of the negative busbar 1 and the cylindrical battery proposed in the present invention is described in detail above with reference to the preferred embodiments. However, those skilled in the art will appreciate that, without departing from the concept of the present invention, various modifications and variations can be made to the above-mentioned specific embodiments, and various technical features and structures proposed in the present invention can be combined in various ways without exceeding the protection scope of the present invention.

Claims

1. A negative busbar, characterized in that: include: The body has a circular outer contour; a welding protrusion protruding from the body toward one side of the negative busbar; and a plurality of buffer protrusions protruding from the body toward the one side of the negative busbar, The welding protrusion is arranged at the center of the negative electrode busbar, and the plurality of buffer protrusions are arranged around the welding protrusion at intervals from each other in a circumferential direction.

2. The negative electrode busbar according to claim 1, characterized in that: The ratio of the protrusion height of the welding protrusion to the protrusion height of the buffer protrusion is 1.0-1.

1.

3. The negative electrode busbar according to claim 1, characterized in that: The protrusion height of the welding protrusion is 0.1-0.3mm, and the protrusion height of the buffer protrusion is 0.1-0.3mm.

4. The negative electrode busbar according to claim 1, characterized in that: The shape of the welding protrusion is one of the following shapes: circular, square, triangular, trapezoidal, and fan-shaped; the shapes of the plurality of buffer protrusions are the same and are one of the following shapes: circular, square, triangular, trapezoidal, and fan-shaped.

5. The negative electrode busbar according to claim 4, characterized in that: The width of the buffer protrusion extending along the circumferential direction of the negative electrode busbar is greater than or equal to 1 mm.

6. The negative electrode busbar according to claim 4, characterized in that: The ratio of the length of the buffer protrusion extending along the radius of the negative electrode busbar to the radius of the negative electrode busbar is 0.2-0.

8.

7. The negative busbar according to any one of claims 1 to 6, characterized in that: The body, the welding protrusions and the plurality of buffer protrusions are formed integrally.

8. The negative busbar according to any one of claims 1 to 6, characterized in that: The shape of the welding protrusion is circular, the edge of the welding protrusion is partially connected to the body, and the ratio of the arc length of the connecting part where the edge of the welding protrusion is connected to the body to the arc length of the disconnected part where the edge of the welding protrusion is disconnected from the body is 0.1-10.

9. A cylindrical battery, characterized in that: include: A shell, the shell comprising a cylindrical barrel and a bottom closing one end of the barrel, and the other end of the barrel is open; A cap configured to be fixedly connected to the other end of the barrel; A winding core is disposed in the shell, and includes a positive electrode tab located at one end of the winding core and a negative electrode tab located at the other end of the winding core; A positive busbar, one side of which is welded to the positive electrode tab of the winding core, and the other side of which is welded to the cap; and A negative electrode busbar is disposed between the negative electrode tab of the winding core and the bottom of the shell, and is configured to be welded to the negative electrode tab of the winding core and the bottom of the shell, respectively. Wherein, the negative electrode busbar is a negative electrode busbar according to any one of claims 1-8, the one side of the negative electrode busbar faces the bottom of the shell, the welding protrusion is configured to be welded to the bottom of the shell, and the multiple buffer protrusions are configured to abut the bottom of the shell.

10. The cylindrical battery according to claim 9, characterized in that: The shape of the welding protrusion is circular, and the weld mark formed by welding the welding protrusion to the bottom of the shell includes an arc-shaped weld mark segment arranged adjacent to the outer periphery of the welding protrusion and a straight weld mark segment extending along the diameter direction of the welding protrusion, and one end of the straight weld mark segment is connected to one end of the arc-shaped weld mark segment.

11. The cylindrical battery according to claim 9 or 10, characterized in that: The welding line of the negative electrode busbar and the negative electrode tab of the winding core is located between two adjacent buffer protrusions and extends outward from the welding protrusion along the radius of the negative electrode busbar.

Images