A negative electrode current collector and a cylindrical secondary battery

Abstract

This utility model proposes a negative electrode current collector and a cylindrical secondary battery. The negative electrode current collector includes a plate body, a tail body, and a connecting part. The plate body and the tail body are fixedly connected by the connecting part. Recessed portions are provided on both sides of the connection between the plate body and the connecting part. The minimum width of the connecting part at the recessed portion is W1. The minimum width of the connecting part near the tail body is W, and it satisfies: W1 / W = 89.3~98.2%. The recessed portions of this negative electrode current collector reduce the bending difficulty during bending, improve operational convenience and efficiency, and serve as a clear indicator for quickly screening the rationality of the bending position, thereby improving production efficiency and product quality.

Description

Technical Field

[0001] This utility model relates to the field of cylindrical battery manufacturing technology, and in particular to a negative electrode current collector and a cylindrical secondary battery. Background Technology

[0002] A cylindrical battery is a type of battery composed of components such as a positive electrode, a negative electrode, a separator, an electrolyte, and a casing. It is cylindrical in shape. Its structure typically includes components such as a casing, a cap, a positive electrode, a negative electrode, a separator, an electrolyte, a PTC element, gaskets, and a safety valve. The edges of the cylindrical battery tabs are equipped with insulating tape to prevent the tabs from contacting the casing wall, which could cause poor casing voltage. This ensures that the battery can charge and discharge normally and provides protection in abnormal conditions.

[0003] A single-pass cylindrical battery with publication number CN220086334U includes a core, a positive current collector, a casing, and an explosion-proof valve. The positive tab of the core is connected to the positive current collector to form a core assembly. The core assembly is disposed within the casing, and the bottom of the casing along its height direction is connected to the positive current collector. The casing has a mounting groove and a first liquid injection hole, and the positive current collector has a second liquid injection hole. The mounting groove, the first liquid injection hole, and the second liquid injection hole are sequentially connected and correspond to the center hole of the core. The explosion-proof valve is disposed in the mounting groove.

[0004] In the existing technology, the negative electrode current collector plate and the tail end connection lack a structural design that facilitates bending, making bending operations difficult and inefficient. Furthermore, there is no effective way for inspectors to quickly screen the rationality of the bending position, making it difficult to quickly identify problems and affecting production efficiency and product quality. Utility Model Content

[0005] In view of this, the present invention proposes a negative electrode current collector and a cylindrical secondary battery. The concave part reduces the bending difficulty when bending the current collector, improves the convenience and efficiency of operation, and can also serve as a clear marker to quickly screen the rationality of the bending position, thereby improving production efficiency and product quality.

[0006] The technical solution of this utility model is implemented as follows: In the first aspect, this utility model provides a negative electrode current collector, including a disk body, a tail body and a connecting part, wherein the disk body and the tail body are fixedly connected by the connecting part;

[0007] The disc body and the connecting part are provided with concave portions on both sides of the connection. The minimum width of the connecting part at the concave portion is W1. The minimum width of the connecting part near the tail body is W, and satisfies: W1 / W = 89.3~98.2%.

[0008] Based on the above technical solutions, preferably, the radius of the disc body is R1, and the radius of the disc body and the minimum width of the connecting part near the tail body satisfy: W / (2×R1)=58.3~72.3%; the radius of the disc body R1=19.45~23.45mm.

[0009] Based on the above technical solutions, preferably, the length of the concave portion is L1, and the length of the concave portion and the radius of the disk body satisfy: L1 / R1=23.3~32.6%.

[0010] Based on the above technical solutions, preferably, the concave portion includes a rounded corner chamfer and an edge chamfer. The rounded corner chamfer is located at the connection between the disc body and the connecting part, and the angle of the rounded corner chamfer is A, where angle A = 80~100°. The edge chamfer is located at the corner on the other side of the concave portion, and the angle of the edge chamfer is B, where angle B = 143~163°.

[0011] Based on the above technical solutions, preferably, the minimum straight-line distance between the center of the disk and the connecting part is L2, and it satisfies the following condition with respect to the radius of the disk: L2 / R1 = 56.9~66.2%.

[0012] Based on the above technical solutions, preferably, a through hole is provided in the center of the disk body, the radius of the through hole is R2, and the radius of the through hole satisfies: R2 / R1 = 14.0~23.3%.

[0013] Based on the above technical solutions, preferably, the disk body is provided with multiple vent holes located outside the through hole, the radius of the vent holes is R3, and the radius of the vent holes and the disk body satisfies: R3 / R1=9.3~18.6%.

[0014] Based on the above technical solutions, preferably, the minimum distance between the through hole and the exhaust hole is L4, and the distance between the through hole and the exhaust hole satisfies the following condition: L4 / R1 = 32.6~42.0%.

[0015] Based on the above technical solutions, preferably, the minimum distance between the exhaust hole and the edge of the disc body is L5, and the distance between L5 and the radius of the disc body satisfies: L5 / R1 = 11.4~20.7%.

[0016] Secondly, this utility model also provides a cylindrical secondary battery, including a negative electrode current collector.

[0017] The negative electrode current collector and cylindrical secondary battery of this invention have the following advantages over the prior art:

[0018] (1) By controlling the ratio of the minimum width W1 of the connecting part located in the concave part to the minimum width W of the connecting part near the tail body within a suitable range, the structural strength of the battery under normal use, production and transportation and vibration scenarios is guaranteed, and problems such as heat generation and melting, deformation and breakage are avoided. At the same time, it can be easily bent, accurately identify the bending position, and reduce the adverse effects on the welding wire.

[0019] (2) By controlling the ratio between the disk radius R1 and the minimum width of the connecting part near the tail body within a suitable range, the cost and weight of the current collector are effectively controlled while ensuring the battery's high-rate charging and discharging overcurrent capability, avoiding interference with the casing, and improving the assembly yield.

[0020] (3) By controlling the chamfer angle A within a suitable range, while avoiding the increase in material costs and the decrease in battery energy density, the plate and the core have sufficient welding area, which improves the welding current capacity and ensures battery performance.

[0021] (4) By controlling the chamfer angle B within a suitable range, burrs at the bend are avoided from affecting battery performance, while the concave part is clearly visible, making it easy for personnel to quickly identify the bend position and improving the initial screening efficiency. Attached Figure Description

[0022] 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.

[0023] Figure 1 This is a perspective view of the negative electrode current collector of this utility model;

[0024] Figure 2 This is a plan view of the unfolded state of the negative electrode current collector of this utility model;

[0025] Figure 3 This is a schematic diagram of the folded state of the negative electrode current collector 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] like Figure 1-3 As shown, this utility model provides a negative electrode current collector, including a plate body 1, a tail body 2, and a connecting part 3. The plate body 1 and the tail body 2 are fixedly connected by the connecting part 3. Recessed portions 300 are provided on both sides of the connection between the plate body 1 and the connecting part 3. The minimum width of the connecting part 3 at the recessed portion 300 is W1. The minimum width of the connecting part 3 on the side closer to the tail body 2 is W, and satisfies: W1 / W = 89.3~98.2%.

[0028] It should be noted that if the width W1 of the connecting part 3 at the concave part 300 is too small, the cross-sectional area of ​​this part will be reduced, resulting in increased resistance and heat generation, which may cause the root to melt. At the same time, the small cross-sectional area will result in weak structural strength. In production, transportation and use scenarios with frequent vibration, it will not be able to withstand external forces and will be prone to deformation, breakage or cracks, which may lead to the generation of metal foreign objects and cause the battery to short circuit.

[0029] If the width W1 of the connecting part 3 at the concave part 300 is too large, it will not serve the purpose of easy bending and identification of the bending position. On the other hand, since the tail body 2 is relatively wide, if the width W1 of the connecting part 3 at the concave part 300 is too large, it will be difficult to bend at the root. More of the tail end 2 length will be required for bending. Moreover, after bending, the large stress and deformation force generated by the root bending will be transmitted to the welding wire of the disc and the core, which will pull on the welding wire and cause the welding wire near the bending point to separate.

[0030] Specifically, in this embodiment, the minimum width W1 of the connecting part 3 located at the concave part 300 is 27mm; the minimum width W of the connecting part 3 near the tail body 2 is 28mm.

[0031] According to this embodiment, by controlling the ratio of the minimum width W1 of the connecting part 3 located at the concave part 300 to the minimum width W of the connecting part 3 near the tail body 2 to 89.3 to 98.2%, the structural strength of the battery under normal use, production and transportation and vibration scenarios is guaranteed, and problems such as heat generation melting, deformation and breakage are avoided. At the same time, it can be easily bent, accurately identify the bending position, and reduce the adverse effects on the welding wire.

[0032] In this embodiment, the radius of the disc body 1 is R1, and the radius of the disc body 1 and the minimum width of the connecting part 3 near the tail body 2 satisfy: W / (2×R1)=58.3~72.3%; the radius of the disc body 1 R1=19.45~23.45mm.

[0033] It should be noted that, according to the principle of current transmission, during the charging and discharging of the battery, the current needs to be conducted through the connecting part 3 of the current collector. The minimum width W of the connecting part 3 near the tail body 2 is W / (2×R1) with the radius R1 of the disk body 1. When this value is too small, the radius of the disk body 1 and the minimum width W of the connecting part 3 near the tail body 2 will be too small, resulting in insufficient overcurrent capacity. When the battery is charged and discharged at a high rate, the overcurrent capacity will not meet the actual needs, and the tail body 2 will heat up, affecting the performance and life of the battery.

[0034] When the value of W / (2×R1) is too large, the radius of the disk body 1 and the minimum width W of the connecting part 3 near the tail body 2 will be too large. This will increase the amount of material required to make the current collector, directly leading to an increase in the production cost of the current collector. At the same time, the weight of the current collector will increase. Since the energy density of the battery is the ratio of the energy stored in the battery to the weight of the battery, the increase in the weight of the current collector will increase the overall weight of the battery. Under the condition that the stored energy remains unchanged, the energy density of the battery will decrease. If the value of W / (2×R1) is too large, the tail body 2 needs to be welded to the cap. During welding and assembly, there is a certain reasonable process offset, which will cause the edge of the current collector to easily interfere with the shell, affecting the subsequent overall assembly, increasing the assembly difficulty and decreasing the assembly yield.

[0035] Specifically, in this embodiment, the radius of the disk body 1 is R1 = 21.45 mm; W / (2×R1) = 65.3%.

[0036] This invention achieves a balance between the radius R1 of the disk body 1 and the minimum width W of the connecting part 3 near the tail body 2, satisfying W / (2×R1)=58.3~72.3% and R1=19.45~23.45mm. This ensures the battery's high-rate charging and discharging overcurrent capability while effectively controlling the cost and weight of the current collector, avoiding interference with the casing, and improving assembly yield.

[0037] In this embodiment, the length of the concave portion 300 is L1, and the length of the concave portion 300 and the radius of the disk body 1 satisfy the following relationship: L1 / R1 = 23.3~32.6%.

[0038] It should be noted that if the L1 / R1 ratio is too small, the length L1 of the concave portion 300 will be too small, resulting in insufficient space for bending operations. During the bending process, there will not be enough length to buffer and disperse the stress generated during bending, making it difficult to complete the bending action accurately and smoothly, thus affecting the effect of root bending. Furthermore, during the initial screening of personnel, the concave portion 300 is used to quickly locate and determine the bending position. When L1 is too small, the feature is not obvious enough, making it difficult to clearly and accurately identify the position of the concave portion 300 during visual observation, which in turn affects the direct judgment of the bending position.

[0039] If the L1 / R1 ratio is too large, the length L1 of the concave portion 300 will be too large, which will disrupt the continuity and integrity of the structure at the tail end, resulting in uneven material distribution in this area. When subjected to external forces, stress concentration is more likely to occur near the concave portion 300. During the production, transportation, and battery manufacturing process of the current collector, the tail end will experience various mechanical stresses. Due to the weakening of strength caused by an excessively large L1, the concave portion 300 is more prone to fracture or cracking, which may produce metallic foreign objects and increase the risk of battery short circuit.

[0040] In this embodiment, the recessed portion 300 includes a rounded chamfer 310 and an edge chamfer 320. The rounded chamfer 310 is provided at the connection between the disc body 1 and the connecting portion 3. The angle of the rounded chamfer 310 is A, and the angle A = 80~100°.

[0041] It should be noted that if the chamfer angle A of 310° is too small, the transition at the connection between the disk body 1 and the connecting part 3 will be relatively smooth and occupy a large space. In order to ensure the stability and connection strength of the overall structure of the current collector, the area of ​​the disk surface needs to be increased accordingly to adapt to this transition form. However, the increase in the disk surface area will increase the amount of material required to make the disk surface, which will directly lead to an increase in material costs. At the same time, the increase in material will increase the overall weight of the current collector. Since the battery energy density is the ratio of the energy stored in the battery to the weight of the battery, if the energy stored in the battery remains unchanged, the increase in weight will inevitably lead to a decrease in the energy density of the battery.

[0042] If the chamfer angle A of 310° is too large, the transition of the rounded corner at the connection between the disc 1 and the connecting part 3 will become sharper and occupy less space. This will compress the area on the surface of the disc 1 and the core that can be welded, reducing the required welding area between the surface of the disc 1 and the core. During the charging and discharging of the battery, the current needs to be conducted through the welding wire. The reduction in the effective welding area will lead to an increase in resistance. During high-current charging and discharging, the increased resistance will cause more heat to be generated at the welding wire, resulting in a higher temperature rise, which will affect the performance of the battery.

[0043] Specifically, in this embodiment, the fillet chamfer angle A = 90°.

[0044] In this embodiment, by setting the angle A of the chamfer 310 to 80-100°, while avoiding increased material costs and decreased battery energy density, sufficient welding area is ensured between the disc and the core, improving welding current carrying capacity and guaranteeing battery performance.

[0045] In this embodiment, the chamfer 320 is located at the corner on the other side of the recess 300. The angle of the chamfer 320 is B, and the angle B = 143° to 163°.

[0046] It should be noted that when the chamfer angle B of 320° is too small, the deformation of the metal material at the bending point will be more severe and concentrated during the bending process. Since the metal material has a certain degree of toughness and plasticity, when the deformation is too severe, the flow and distribution of the material will be uneven, which will easily produce burrs at the bending point. This will not only affect the flatness and smoothness of the current collector surface, but also, during battery use, the burrs may puncture critical components such as the separator inside the battery, thereby causing a short circuit and seriously affecting the battery's performance and safety.

[0047] When the chamfer angle B of 320° is too large, it becomes difficult for personnel to quickly distinguish the bending position when visually identifying it. More time and effort are required to carefully observe and judge, which increases the difficulty of identifying the position and reduces the identification efficiency.

[0048] Specifically, in this embodiment, the angle B of the chamfer 320 is 153°.

[0049] In this embodiment, by setting the angle B of the chamfer 320 to 143-163°, it avoids burrs at the bend from affecting battery performance, while ensuring that the concave part 300 is obvious, making it easy for personnel to quickly identify the bend position and improving the initial screening efficiency.

[0050] In this embodiment, the minimum straight-line distance between the center of the disk body 1 and the connecting part 3 is L2, and the radius of the disk body 1 satisfies: L2 / R1 = 56.9~66.2%.

[0051] It should be noted that when the minimum straight-line distance L2 between the center of the disc body 1 and the connecting part 3 is too small, the distance between the root of the disc body 1 and the center of the disc body 1 is too small, which affects the effective welding area of ​​the disc body 1 and the core. As a result, the effective welding area is too small during welding, the welding current capacity is insufficient, the temperature rises at the welding line, and the battery performance is affected.

[0052] When the minimum straight-line distance L2 between the center of the disk body 1 and the connecting part 3 is too large, the overall size of the current collector will increase accordingly, the amount of material required to make the current collector will increase, resulting in higher production and manufacturing costs. At the same time, the weight of the current collector will increase. Since the energy density of a battery is the ratio of the energy stored in the battery to the weight of the battery, the increase in weight will reduce the energy density of the battery if the stored energy remains unchanged. Furthermore, it will affect subsequent processes such as inserting the insulating ring, which will affect the subsequent overall assembly, increase the assembly difficulty, and decrease the assembly yield.

[0053] Specifically, in this embodiment, the minimum straight-line distance L2 between the center of the disc body 1 and the connecting part 3 is 13.2 mm.

[0054] In this embodiment, by satisfying the minimum straight-line distance L2 between the center of the disk 1 and the connecting part 3 and the disk radius R1 to L2 / R1 = 56.9~66.2%, the cost and weight of the current collector are effectively controlled, the welding current carrying capacity is improved to ensure battery performance, and the size problem is avoided from affecting subsequent assembly processes, thus improving the assembly yield.

[0055] In this embodiment, a through hole 100 is provided in the center of the disk body 1. The radius of the through hole 100 is R2, and it satisfies the following with the radius of the disk body 1: R2 / R1 = 14.0~23.3%.

[0056] It should be noted that when the radius R2 of the through hole 100 is too small, that is, when the radius of the through hole 100 relative to the disk body 1 is too small, the electrolyte will be limited by the size of the through hole 100 when it is injected into the battery from above the disk body 1. The through hole 100 being too small will narrow the channel for the electrolyte to flow into the battery, which will increase the resistance to electrolyte flow, and thus make the electrolyte flow into the battery take longer, reduce the injection efficiency, and thus increase the manufacturing cost of the battery. At the same time, during the charging and use of the battery, gas will be generated inside the battery. The through hole 100 being too small will also affect the gas discharge rate, which will lead to an increase in the internal pressure of the battery, affecting the performance and safety of the battery.

[0057] If the radius of the through hole 100 is too large, the through hole 100 will occupy the welding area between the disc body 1 and the core. The disc body 1 and the core are fixed by welding, and the size of the welding area directly affects the effective area of ​​the welding line. If the effective area of ​​the welding line is reduced, the current carrying capacity at the welding line will decrease, the temperature rise at the welding line will increase, and the performance of the battery will be affected.

[0058] Specifically, in this embodiment, the radius R2 of the through hole 100 is 4mm.

[0059] In this embodiment, by reasonably setting the ratio range between the radius of the through hole 100 and the radius of the disk body 1, the size of the through hole 100 can ensure that the electrolyte flows into the battery quickly and smoothly, improving the electrolyte injection efficiency, while ensuring that the gas can be discharged in time to maintain the stability of the internal pressure of the battery; at the same time, it can also ensure that the disk body 1 and the core have sufficient welding area to maintain the current carrying capacity of the welding wire and avoid excessive temperature rise at the welding wire, thereby ensuring the performance and safety of the battery.

[0060] In this embodiment, the disk body 1 has multiple vent holes 110, which are located outside the through hole 100. The radius of the vent hole 110 is R3, and the radius of the vent hole 110 and the disk body 1 satisfy: R3 / R1 = 9.3~18.6%.

[0061] It should be noted that during the battery electrolyte injection process, the vent hole 110 not only serves to expel the gas inside the battery, but also assists in the injection of electrolyte to a certain extent. When the radius R3 of the vent hole 110 is too small, the area of ​​the vent hole 110 will be too small. During the electrolyte injection, the speed at which the gas inside the battery is expelled will slow down, and a certain gas pressure will be formed inside the battery to hinder the entry of electrolyte. This will reduce the amount of electrolyte that enters the battery through the vent hole 110 per unit time, thereby slowing down the speed of electrolyte injection, reducing the electrolyte injection efficiency, and ultimately affecting the overall production efficiency.

[0062] The disc body 1 and the core need to be welded to establish a stable electrical connection to ensure smooth current conduction. When the radius R3 of the vent hole 110 is too large, multiple vent holes 110 will occupy a large area of ​​the disc body 1, thereby significantly reducing the weldable area between the disc body 1 and the core, increasing the resistance of the welded part, resulting in increased heat generation at the weld line, increased temperature rise, affecting the performance and stability of the internal materials of the battery, and thus affecting the overall performance of the battery.

[0063] Specifically, in this embodiment, the radius R3 of the exhaust hole 110 is 3mm.

[0064] This invention ensures that the radius R3 of the vent hole 110 and the radius R1 of the disk body 1 satisfy R3 / R1=9.3-18.6%, which guarantees the battery electrolyte injection efficiency, improves the overall production efficiency, ensures that the disk surface has sufficient weldable area, enhances the current carrying capacity of the welding wire, and guarantees the battery performance.

[0065] In this embodiment, the minimum distance between the through hole 100 and the vent hole 110 is L4, and the radius of the disk body 1 satisfies: L4 / R1 = 32.6~42.0%.

[0066] It should be noted that when the minimum distance L4 between the through hole 100 and the vent hole 110 is too small, there is relatively little metal material between the two holes. During battery production, transportation and use, the disc body 1 will be subjected to various forces. Due to the lack of material here, its ability to withstand stress will be weakened, its strength will be reduced, and it will be prone to deformation or even breakage, producing burrs and metal foreign objects. Burrs and metal foreign objects may puncture the separator inside the battery and cause a short circuit; or they may enter the electrolyte, affecting the performance of the electrolyte and thus affecting the overall performance of the battery.

[0067] When the minimum distance L4 between the through hole 100 and the vent hole 110 is too large, the distance between the outer vent hole 110 and the edge of the disc body 1 will be too small. The edge of the disc body 1 is also easily subjected to external forces during the manufacturing and use of the battery. Since there is less material here, its ability to withstand stress will be weakened, its strength will be reduced, and it will be easy to deform or even break, producing burrs and metal foreign objects. Burrs and metal foreign objects may puncture the separator inside the battery and cause a short circuit in the battery; or enter the electrolyte, affecting the performance of the electrolyte and thus affecting the overall performance of the battery.

[0068] Specifically, in this embodiment, the minimum distance L4 between the through hole 100 and the vent hole 110 is 8mm.

[0069] In this embodiment, by satisfying the minimum distance L4 between the through hole 100 and the vent hole 110 with the radius R1 of the disk body 1, L4 / R1 = 32.6-42.0%, the deformation and breakage caused by insufficient strength between the through hole 100 and the vent hole 110 and at the edge of the disk body 1, as well as the generation of burrs and metal foreign objects, are avoided, thus ensuring the stable operation of the battery.

[0070] In this embodiment, the minimum distance between the exhaust hole 110 and the edge of the disc 1 is L5, and the radius of the disc 1 satisfies: L5 / R1 = 11.4~20.7%.

[0071] It should be noted that when the minimum distance L5 between the vent hole 110 and the edge of the disk body 1 is too small, the vent hole 110 is close to the edge of the disk body 1. There is less material at this point, so its ability to withstand stress will be weakened, its strength will be reduced, and it will be prone to deformation or even breakage, producing burrs and metal foreign objects. Burrs and metal foreign objects may puncture the separator inside the battery, causing a short circuit; or they may enter the electrolyte, affecting the performance of the electrolyte and thus affecting the overall performance of the battery.

[0072] When the minimum distance L5 between the vent hole 110 and the edge of the disk body 1 is too large, the distance between the vent holes 110 becomes too small. As a result, there will be relatively less metal material between adjacent vent holes 110, which will weaken its ability to withstand stress, reduce its strength, and make it prone to deformation or even breakage, producing burrs and metal foreign objects. Burrs and metal foreign objects may puncture the separator inside the battery, causing a short circuit; or they may enter the electrolyte, affecting the performance of the electrolyte and thus affecting the overall performance of the battery.

[0073] Specifically, in this embodiment, the minimum distance L5 between the vent 110 and the edge of the disc 1 is 3.45 mm.

[0074] In this embodiment, by satisfying the minimum distance L5 between the vent hole 110 and the edge of the disk body 1 and the radius R1 of the disk body 1, L5 / R1 = 11.4-20.7%, the distance between the vent hole 110 and the edge of the disk body 1, as well as the distance between the vent hole 110 and the vent hole 110, is reasonably balanced. This avoids the problem of deformation and breakage due to excessively low local strength of the disk body 1 caused by improper distance, as well as the generation of burrs and metal foreign objects, thus effectively ensuring the performance and safety of the battery.

[0075] Secondly, this utility model also provides a cylindrical secondary battery, including a negative electrode current collector.

[0076] 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, characterized in that, It includes a disc body (1), a tail body (2) and a connecting part (3), wherein the disc body (1) and the tail body (2) are fixedly connected by the connecting part (3); The disc body (1) and the connecting part (3) are provided with concave portions (300) on both sides of the connection. The minimum width of the connecting part (3) at the concave portion (300) is W1. The minimum width of the connecting part (3) on the side closer to the tail body (2) is W, and satisfies: W1 / W = 89.3~98.2%.

2. The negative electrode current collector as described in claim 1, characterized in that, The radius of the disc (1) is R1, and the radius of the disc (1) and the minimum width of the connecting part (3) near the tail (2) satisfy: W / (2×R1)=58.3~72.3%; the radius of the disc (1) R1=19.45~23.45mm.

3. The negative electrode current collector as described in claim 2, characterized in that: The length of the concave portion (300) is L1, and the length of the concave portion (300) and the radius of the disk body (1) satisfy: L1 / R1 = 23.3~32.6%.

4. The negative electrode current collector as described in claim 1, characterized in that: The recessed portion (300) includes a rounded chamfer (310) and an edge chamfer (320). The rounded chamfer (310) is located at the connection between the disc body (1) and the connecting portion (3). The angle of the rounded chamfer (310) is A, and the angle A = 80 to 100°. The edge chamfer (320) is located at the corner on the other side of the recessed portion (300). The angle of the edge chamfer (320) is B, and the angle B = 143 to 163°.

5. The negative electrode current collector as described in claim 1, characterized in that: The minimum straight-line distance between the center of the disk (1) and the connecting part (3) is L2, and the radius of the disk (1) satisfies: L2 / R1 = 56.9~66.2%.

6. The negative electrode current collector as described in claim 1, characterized in that: The disk body (1) has a through hole (100) at its center. The radius of the through hole (100) is R2, and it satisfies the following with the radius of the disk body (1): R2 / R1 = 14.0~23.3%.

7. The negative electrode current collector as described in claim 6, characterized in that: The disk body (1) has multiple vent holes (110) and is located outside the through hole (100). The radius of the vent hole (110) is R3, and the radius of the vent hole (110) and the disk body (1) satisfy: R3 / R1 = 9.3~18.6%.

8. The negative electrode current collector as described in claim 7, characterized in that: The minimum distance between the through hole (100) and the vent hole (110) is L4, and the radius of the disk body (1) satisfies: L4 / R1 = 32.6~42.0%.

9. The negative electrode current collector as described in claim 7, characterized in that: The minimum distance between the exhaust hole (110) and the edge of the disc (1) is L5, and the radius of the disc (1) satisfies: L5 / R1=11.4~20.7%.

10. A cylindrical secondary battery, characterized in that, Includes the negative current collector as described in any one of claims 1-9.

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