A cylindrical secondary battery

Abstract

The utility model provides a kind of cylindrical secondary battery, including the side of shell is equipped with round hole, and shell is equipped with recess;The both ends of pole respectively are threaded round hole and project outward, and pole is interval with shell setting;Lower plastic is embedded between the one side of shell and pole and inserted into shell, and lower plastic and the inner wall of shell are abutted;Upper plastic is sleeved in the outside of pole, and both sides are respectively with pole and shell abutted, and the bottom end of upper plastic is threaded and extends into round hole;Sealing ring is sleeved in the outside of pole, and both sides are respectively with shell, pole and the lower end surface of upper plastic abutted;The depth of recess is H12, the thickness of shell is H11, and satisfy: H12 / H11=21%-36%;By setting pole, shell, upper plastic and lower plastic as concave-convex platform structure, realize closely nested combination, control the proportion size of shell thickness and recess depth simultaneously, effectively improve the pole anti-twist stability and air tightness, improve the safety performance of battery.

Description

Technical Field

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

[0002] In existing cylindrical battery technology, the terminals of cylindrical batteries are commonly cylindrical. They are used in conjunction with the through holes in the casing and a series of plastic parts for insulation and sealing. The terminals are fixed by riveting the flanges. The terminals are often used as the positive terminal of the battery for welding.

[0003] A cylindrical battery terminal structure with a split-shell design, disclosed in CN222214419U, includes a terminal, a circular piece riveted to the outside of the terminal, a sealing gasket between the terminal and the circular piece, a bottom of the terminal welded to the center of a current collector, an insulating sheet fastened to the current collector, the inner side of the insulating sheet extending between the circular piece and the current collector, and several perforations on the outer side of the insulating sheet. The current collector and the core's tabs are welded to the perforations. The outer shell holds the circular piece, insulating sheet, terminal, current collector, and core. The terminal extends upward through a through hole to the top outer side of the outer shell. Laser welding is performed between the outer shell and the circular piece.

[0004] In existing cylindrical battery technology, the terminals are mostly cylindrical, and are used with the casing through holes and plastic parts to achieve insulation, sealing and fixation. The positive end is often welded. However, the terminals of this type of structure have very weak torsional resistance. They are prone to torsion in vibration and bumpy scenarios such as vehicles and power tools, which can lead to loosening of the riveting and failure of airtightness, causing safety problems such as leakage. Utility Model Content

[0005] In view of this, the present invention proposes a cylindrical secondary battery, which effectively improves the anti-torsion stability and airtightness of the electrode post and enhances the safety performance of the battery by forming a tight nested structure of the electrode post, shell, upper plastic and lower plastic, and controlling the ratio of shell thickness to groove depth.

[0006] The technical solution of this utility model is achieved as follows: This utility model provides a cylindrical secondary battery, comprising: The shell has a round hole on one side and a groove on the shell. The two ends of the pole extend outward through the circular holes, and the pole and the housing are spaced apart. The lower plastic is embedded between the housing and the side of the pole that extends into the housing, and the lower plastic abuts against the inner wall of the housing; The plastic is fitted onto the outside of the electrode post, with both sides abutting against the electrode post and the housing respectively, and the bottom end of the plastic extends through and into the round hole. The sealing ring is fitted on the outside of the pole post, and its two sides abut against the lower end face of the housing, the pole post and the upper plastic, respectively, so that the pole post and the housing are relatively fixed. The groove has a depth of H12 and the shell has a thickness of H11. The groove depth and the shell thickness satisfy: H12 / H11=21%-36%.

[0007] Based on the above technical solutions, preferably, the width of the groove is L11, the shortest distance from the edge of the circular hole to the edge of the shell is L10, and the width of the groove and the shortest distance from the edge of the circular hole to the edge of the shell satisfy: L11 / L10=8%-14%.

[0008] Based on the above technical solutions, preferably, the shortest distance from the edge of the circular hole to the edge of the groove is L12, and the shortest distance from the edge of the circular hole to the edge of the groove and the shortest distance from the edge of the circular hole to the edge of the shell satisfy: L12 / L10=17%-25%.

[0009] Based on the above technical solutions, preferably, the radius of the shell is R1, and the shortest distance from the edge of the circular hole to the edge of the shell satisfies the following condition with respect to the radius of the shell: L10 / R1=60%-70%.

[0010] Based on the above technical solutions, preferably, the height of the pole post is H10, and the thickness of the shell and the height of the pole post satisfy the following relationship: H11 / H10=13%-24%.

[0011] Based on the above technical solutions, preferably, the pole post includes an upper end, a connecting part, and a lower end, wherein, The upper end is located outside the shell, and the diameter of the upper end is L50; The lower end is located inside the housing, and the diameter of the lower end is L52; The two ends of the connecting part pass through circular holes and are fixedly connected to the upper end and the lower end, and the diameter of the connecting part is L51; The two end faces of the lower plastic abut against the lower end and the inner wall of the shell, respectively; The sealing ring is sleeved on the outside of the connecting part, with its lower end face abutting against the lower end face, and its upper end face abutting against the inner wall of the housing and the lower end face of the upper end face; The upper plastic sleeve is installed on the outside of the connecting part, and its two sides abut against the upper end and the shell respectively.

[0012] Based on the above technical solutions, preferably, the diameter of the shell is D1, and the diameter of the lower end and the diameter of the shell satisfy the following relationship: L52 / D1=52%-61%.

[0013] Based on the above technical solutions, preferably, the diameter of the connecting part and the diameter of the lower end part satisfy the following condition: L51 / L52=50%-65%.

[0014] Based on the above technical solutions, preferably, the diameter of the upper end and the diameter of the lower end satisfy the following condition: L50 / L52=94.6%-98.5%.

[0015] Based on the above technical solutions, preferably, the number of grooves is multiple, and the multiple grooves are evenly distributed in a ring along the center of the circular hole, and the grooves are arranged in an arc shape, with the arc A of the groove being 20-60°.

[0016] The cylindrical secondary battery of this invention has the following advantages over the prior art: (1) By nesting and cooperating the upper groove of the shell with the lower plastic and upper plastic parts, and the fixing effect of the sealing ring, a stable pole structure is formed. At the same time, by controlling the ratio of shell thickness to groove depth, the rotation of the pole can be effectively restricted, the torsional stability of the pole can be effectively improved, the battery life can be extended, and the risk of battery failure can be reduced. (2) The multi-layer sealing structure is formed by the synergistic action of the lower plastic, sealing ring and upper plastic, which effectively prevents external moisture and dust from entering and internal electrolyte from leaking, improving battery safety and service life. At the same time, the components are closely connected and cooperate, so that the pole is installed firmly on the shell, reducing shaking, ensuring the overall structural stability of the battery, and facilitating the normal operation of the battery under various working conditions. (3) By controlling the ratio of the groove width to the shortest distance from the edge of the circular hole to the edge of the shell, and the ratio of the shortest distance from the edge of the circular hole to the edge of the shell to the radius of the shell, the torsional resistance can be improved, the assembly can be made accurate and stable, and the reliability and safety of the battery structure and connection can be improved. Attached Figure Description

[0017] 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.

[0018] Figure 1 This is a schematic diagram of the cylindrical secondary battery of this utility model; Figure 2 This is a diagram showing the groove structure of the cylindrical secondary battery of this utility model. Figure 3 This is a cross-sectional view of the electrode and casing structure of the cylindrical secondary battery of this utility model. Figure 4 This is a diagram showing the terminal structure of the cylindrical secondary battery of this utility model. Figure 5 This is a perspective view of the casing of the cylindrical secondary battery of this utility model; Figure 6 This is a top view of the casing of the cylindrical secondary battery of this utility model. Detailed Implementation

[0019] 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.

[0020] like Figure 1-6 As shown, a cylindrical secondary battery of this utility model includes a shell 1, an electrode post 2, a lower plastic 3, an upper plastic 4, and a sealing ring 5.

[0021] The housing 1 has a circular hole 100 on one side and a groove 110 on the housing 1. The two ends of the pole 2 extend outward through the circular hole 100 and are spaced apart from the housing 1. The lower plastic 3 is embedded between the housing 1 and the side of the pole 2 that extends into the housing 1, and the lower plastic 3 abuts against the inner wall of the housing 1. The upper plastic 4 is fitted on the outside of the pole 2 and abuts against the pole 2 and the housing 1 on both sides, and the bottom end of the upper plastic 4 extends into the circular hole 100. The sealing ring 5 is fitted on the outside of the pole 2 and abuts against the lower end faces of the housing 1, the pole 2 and the upper plastic 4 on both sides, so that the pole 2 and the housing 1 are relatively fixed. The depth of the groove 110 is H12 and the thickness of the housing 1 is H11, and the depth of the groove 110 and the thickness of the housing 1 satisfy: H12 / H11=21%-36%.

[0022] It should be noted that a stable terminal post structure is formed through the nesting and cooperation of the groove 110 on the housing 1 with the lower plastic 3 and the upper plastic component, as well as the fixing effect of the sealing ring 5. Under frequent vibration or bumpy conditions of the battery, this nesting structure can effectively restrict the rotation of the terminal post 2, greatly improve the torsional resistance of the terminal post 2, and reduce problems such as loosening and airtightness failure caused by the torsion of the terminal post 2, thereby extending the battery's service life and reducing the risk of battery failure. Furthermore, the sealing ring 5 is fitted on the outside of the terminal post 2 and tightly abuts against the lower end face of the housing 1, the terminal post 2, and the upper plastic 4. Its elastic properties allow the sealing ring 5 to fill the tiny gap between the terminal post 2 and the housing 1, effectively preventing electrolyte leakage inside the battery, ensuring the battery's airtightness, avoiding safety hazards such as fire and explosion caused by leakage, and improving the battery's safety performance.

[0023] In addition, the height of the groove 110 and the depth of the shell 1 satisfy H12 / H11=21%-36%. When the ratio is within this range, a good nesting anti-torsion effect can be achieved. If the ratio is too small, that is, the height H12 of the groove 110 is too small, the nesting depth of the groove 110 and other components is insufficient. When the battery is subjected to vibration or torsional force, it cannot provide sufficient restraint, which weakens the nesting anti-torsion ability and increases the risk of the pole post 2 torsion. If the ratio is too large, that is, the height H12 of the groove 110 is too large, the processing accuracy and process requirements are higher during the manufacturing process, the manufacturing difficulty increases, and processing defects are more likely to occur, resulting in low yield and thus increasing manufacturing costs.

[0024] In this embodiment, by reasonably controlling the ratio of the height of the groove 110 to the depth of the housing 1, the problems of increased manufacturing difficulty, low yield and increased manufacturing cost caused by excessive groove depth are avoided; the anti-torsion effect is also not affected by excessive groove depth, thus effectively ensuring the anti-torsion ability and sealing performance of the pole post 2.

[0025] Specifically, the ratio of the height of the groove 110 to the depth of the shell 1 is: H12 / H11=0.2 / 0.7=28.6%.

[0026] In this embodiment, the width of the groove 110 is L11, the shortest distance from the edge of the circular hole 100 to the edge of the shell 1 is L10, and the width of the groove 110 and the shortest distance from the edge of the circular hole 100 to the edge of the shell 1 satisfy: L11 / L10=8%-14%.

[0027] It should be noted that when L11 / L10 is too small, the width of the corresponding groove 110 is too small. When the battery is subjected to external forces, especially when torsion occurs, the insufficient nesting area cannot provide enough friction and constraint to resist the torsional force, and thus cannot play the role of nesting to prevent torsion. When L11 / L10 is too large, the width of the corresponding groove 110 is too large. Since the shell material is usually metal, it is normally required to be processed and manufactured by die stamping. If the width of the groove 110 is too wide, the deformation of the metal material will increase during the die stamping process, making the die stamping more difficult, which will increase the difficulty of production and processing, reduce the product yield, and thus increase the manufacturing cost.

[0028] In this embodiment, by reasonably controlling the ratio of the width L11 of the groove 110 to the shortest distance L10 from the edge of the circular hole 100 to the edge of the shell 1, the torsional resistance of the battery can be improved, the manufacturing difficulty and cost can be reduced, and the product reliability can be improved.

[0029] Specifically, the ratio of the width of the groove 110 to the shortest distance from the edge of the circular hole 100 to the edge of the housing 1 is: L11 / L10 = 1.6 / 14.9mm = 10.7%.

[0030] In this embodiment, the shortest distance from the edge of the circular hole 100 to the edge of the groove 110 is L12, and the shortest distance from the edge of the circular hole 100 to the edge of the groove 110 and the shortest distance from the edge of the circular hole 100 to the edge of the housing 1 satisfy: L12 / L10=17%-25%.

[0031] It should be noted that when L12 / L10 is too small, the nesting space between the groove 110, the lower plastic 3, and the terminal 2 in the battery structure becomes extremely limited. Since each component requires a certain amount of space to ensure accurate positioning and tight fit during assembly, an excessively short L12 prevents the groove 110 from providing sufficient area for the lower plastic 3 and the terminal 2 to be accommodated and nested, resulting in inaccurate nesting and affecting the stability and reliability of the battery's internal structure. When L12 / L10 is too large, the gap between the groove 110, the lower plastic 3, and the terminal 2 becomes too large. This excessive gap causes the lower plastic component and the terminal to wobble within the groove 110, making accurate positioning and fixation impossible. Under external force, they are prone to loosening, thus preventing accurate nesting and affecting the battery's performance and safety.

[0032] In this embodiment, by reasonably controlling the ratio of the shortest distance from the edge of the circular hole 100 to the edge of the groove 110 to the shortest distance from the edge of the circular hole 100 to the edge of the housing 1, the groove 110 can provide a precise nesting space for the components below, ensuring accurate and stable assembly and improving the reliability and safety of the battery structure and connection.

[0033] Specifically, the ratio of the shortest distance from the edge of the circular hole 100 to the edge of the groove 110 to the shortest distance from the edge of the circular hole 100 to the edge of the shell 1 satisfies: L12 / L10=3.1 / 14.9=20.8%.

[0034] In this embodiment, the radius of the shell 1 is R1, and the shortest distance from the edge of the circular hole 100 to the edge of the shell 1 satisfies the following condition with respect to the radius of the shell 1: L10 / R1=60%-70%.

[0035] It should be noted that when L10 / R1 is too small, the bottom length of the casing 1 becomes too short, requiring the diameter of the corresponding terminal 2 and the surrounding seals to be enlarged, increasing the battery cost and weight, and reducing the battery energy density. When L10 / R1 is too large, the bottom length of the casing 1 becomes too long, reducing the diameter of the corresponding terminal 2 and the surrounding seals. This reduces the weldable area between the top of the terminal 2 and the positive current collector, resulting in insufficient weldable area on the lower surface of the terminal 2 and the positive current collector, leading to increased temperature at the welding point and consequently affecting battery performance.

[0036] In this embodiment, by reasonably controlling the L10 / R1 ratio, the relationship between the casing 1, the terminal post 2, and the sealing ring 5 can be balanced, avoiding problems such as increased cost and weight, reduced energy density, or insufficient weldable area leading to overheating caused by improper ratio, thus ensuring the performance and cost of the battery.

[0037] Specifically, the ratio of the shortest distance from the edge of the circular hole 100 to the edge of the shell 1 to the radius of the shell 1 satisfies: L10 / R1=14.9 / 23=64.8%.

[0038] In this embodiment, the height of pole post 2 is H10, and the thickness of housing 1 and the height of pole post 2 satisfy the following relationship: H11 / H10=13%-24%.

[0039] It should be noted that when H11 / H10 is too small, the wall thickness of casing 1 is too thin. During battery use, it will be subjected to various external forces, such as the mechanical forces when the battery is moved or vibrated, as well as the stress generated inside the battery due to charging and discharging. Due to the insufficient wall thickness of casing 1, its resistance to deformation will be significantly reduced, and it will be prone to deformation under the continuous action of these external forces. This will lead to a decrease in the long-term reliability of the seal, which may cause safety problems such as battery leakage. When H11 / H10 is too large, that is, the wall thickness of casing 1 is too thick, the energy density of the battery refers to the electrical energy stored per unit mass or unit volume of the battery. Increasing the wall thickness of casing 1 will increase the overall weight of the battery and decrease the energy density of the battery, thus affecting the performance of the battery.

[0040] In this embodiment, by reasonably controlling the ratio of H11 / H10, the depth of the casing 1 and the height of the electrode post 2 can be balanced, avoiding safety and stability problems or weight and energy density problems caused by improper wall thickness, thereby improving the performance of the battery.

[0041] Specifically, in this embodiment, the ratio between the depth of the housing 1 and the height of the pole post 2 satisfies: H11 / H10=0.7 / 3.8mm=18.4%.

[0042] In this embodiment, the pole post 2 includes an upper end 21, a connecting part 22, and a lower end 23. The upper end 21 is located outside the housing 1, and the diameter of the upper end 21 is L50. The lower end 23 is located inside the housing 1, and the diameter of the lower end 23 is L52. The two ends of the connecting part 22 pass through the circular holes 100 and are fixedly connected to the upper end 21 and the lower end 23, and the diameter of the connecting part 22 is L51. The two end faces of the lower plastic 3 abut against the lower end 23 and the inner wall of the housing 1, respectively. The sealing ring 5 is sleeved on the outside of the connecting part 22, and its lower end face abuts against the lower end 23, and its upper end face abuts against the inner wall of the housing 1 and the lower end face of the upper end 21. The upper plastic 4 is sleeved on the outside of the connecting part 22, and its two sides abut against the upper end 21 and the housing 1, respectively.

[0043] It should be noted that the synergistic effect of the lower plastic 3, sealing ring 5, and upper plastic 4 forms a multi-layered sealing structure, which can effectively prevent external moisture, dust, and other contaminants from entering the battery casing, avoiding safety issues such as battery performance degradation and short circuits caused by environmental factors. It also prevents electrolyte leakage inside the casing, improving battery safety and lifespan. Furthermore, the tight contact and cooperation between the components make the installation of the terminal post 2 on the casing 1 more stable. The upper plastic 4 and lower plastic 3 respectively fix the terminal post in the vertical direction, reducing the shaking caused by vibration, impact, and other factors during use, ensuring the stability of the overall battery structure, and facilitating normal battery operation under various working conditions.

[0044] In this embodiment, the diameter of the shell 1 is D1, and the diameter of the lower end 23 satisfies the following relationship with the diameter of the shell 1: L52 / D1=52%-61%.

[0045] It should be noted that when the L52 / D1 ratio is too small, the contact area between the bottom of the lower end 23 and the positive current collector is significantly reduced, the solderable area becomes smaller, and the current carrying capacity at the solder joint decreases, causing the current to concentrate at the solder joint, generating more heat, and thus increasing the temperature at the solder joint. If the L52 / D1 ratio is too large, the overall size of the terminal 2 will increase accordingly, resulting in an increase in the weight of the terminal 2. At the same time, manufacturing a larger terminal requires more raw materials, leading to an increase in battery cost. Moreover, the increased weight of the terminal 2 will occupy more space and weight within the battery. With a fixed total battery volume and weight, the proportion of effective components such as cells used to store electrical energy inside the battery is relatively reduced, thereby decreasing the energy density of the battery.

[0046] This embodiment, by reasonably controlling the L52 / D1 ratio, can ensure sufficient current carrying capacity in the welding area and at the welding line, stabilize the battery performance, and at the same time avoid increasing weight cost and reducing energy density.

[0047] In this embodiment, the diameter of the connecting portion 22 and the diameter of the lower end portion 23 satisfy the following relationship: L51 / L52 = 50%-65%.

[0048] It should be noted that if the ratio of L51 / L52 is too small, the current carrying capacity of the terminal 2 will decrease, and it will be unable to conduct large currents in a timely and effective manner. This will cause the current to concentrate at the connection part 22, generating a large amount of heat, which will affect the performance of the battery. If the ratio of L51 / L52 is too large, that is, the diameter of the connection part 22 is too thick relative to the diameter of the lower end 23, then the overall weight of the terminal 2 will increase significantly. This will lead to an increase in the weight of the terminal 2, and the increased weight of the terminal 2 will occupy more space and weight quota inside the battery. With a fixed total battery volume and weight, the proportion of effective components such as cells used to store electrical energy inside the battery will be relatively reduced, thereby reducing the energy density of the battery.

[0049] This embodiment, by reasonably controlling the ratio of L51 / L52, can ensure the overcurrent capacity of the terminal 2, avoid the generation of a large amount of heat when the overcurrent capacity is insufficient during high-rate charging and discharging, maintain the performance of the battery, reduce the weight and cost of the terminal, and improve the energy density of the battery.

[0050] In this embodiment, the diameter of the upper end 21 and the diameter of the lower end 23 satisfy the following condition: L50 / L52 = 94.6%-98.5%.

[0051] It should be noted that if the L50 / L52 ratio is too small, meaning the diameter of the upper end 21 is relatively small, the upper surface of the terminal 2 needs to be welded to the busbar outside the battery to form a battery pack. A small diameter of the upper end 21 will significantly reduce the area that can be welded. A small welding area will reduce the current carrying capacity at the welding line. The reduced current carrying capacity will cause the current to be relatively concentrated at the welding line, generating more heat and thus increasing the temperature at the welding line, affecting battery performance. If the L50 / L52 ratio is too large, meaning the diameter of the upper end 21 is relatively large, the increased diameter of the upper end 21 will increase the weight of the terminal 2, occupying more space and weight within the battery. With a fixed total battery volume and weight, the proportion of effective components such as cells used to store electrical energy inside the battery will be relatively reduced, thus reducing the energy density of the battery. Furthermore, if the diameter of the upper end 21 is too large, the terminal flange will be too long. During long-term use, the reliability of the riveted part will be reduced, and the long-term stability of the airtightness will be difficult to guarantee.

[0052] This embodiment ensures the weldable area and current carrying capacity by reasonably controlling the L50 / L52 ratio to be too small, thereby reducing temperature rise and stabilizing performance; at the same time, it avoids increasing weight and cost and reducing energy density, ensuring the reliability and airtightness of riveting.

[0053] In this embodiment, there are multiple grooves 110, and the multiple grooves 110 are evenly distributed in a ring along the center of the circular hole 100. The grooves 110 are arranged in an arc shape, and the arc A of the grooves 110 is 20-60°.

[0054] It should be noted that the arc angle A of the groove 110 in this embodiment is 40°. When the arc angle A of the groove 110 is too small, the effective area of ​​the concave and convex platforms is too small, and the ability to achieve nesting and anti-torsion will decrease. When the arc angle A of the groove 110 is too large, the manufacturing process will become more difficult, and the manufacturing cost will increase accordingly.

[0055] This embodiment, by reasonably controlling the curvature of the groove 110, avoids both small angles that result in a small effective area and weak anti-torsion capability, affecting the stability of the battery structure, and large angles that lead to difficult manufacturing processes and high costs, thus ensuring the stability and reliability of the battery structure.

[0056] In this embodiment, the shortest distance L10 from the edge of the circular hole 100 to the edge of the shell 1 is 13.9-15.9 mm; the radius R1 of the shell 1 is 21-25 mm.

[0057] Specifically, in this embodiment, the radius of the shell 1 is R1=23mm, and the shortest distance from the edge of the circular hole 100 to the edge of the shell 1 is L10=14.9mm.

[0058] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A cylindrical secondary battery, characterized in that, include: The housing (1) has a round hole (100) on one side and a groove (110) on the housing (1). The pole post (2) extends outward through the circular holes (100) at both ends, and the pole post (2) and the housing (1) are spaced apart; The lower plastic (3) is embedded between the housing (1) and the side of the pole (2) that extends into the housing (1), and the lower plastic (3) abuts against the inner wall of the housing (1); The upper plastic (4) is fitted on the outside of the pole post (2), and both sides abut against the pole post (2) and the shell (1) respectively. The bottom end of the upper plastic (4) penetrates and extends into the round hole (100). The sealing ring (5) is fitted on the outside of the pole (2), and its two sides abut against the lower end face of the housing (1), the pole (2) and the upper plastic (4) respectively, so that the pole (2) and the housing (1) are relatively fixed. The groove (110) has a depth of H12 and the shell (1) has a thickness of H11. The depth of the groove (110) and the thickness of the shell (1) satisfy: H12 / H11=21%-36%.

2. The cylindrical secondary battery as described in claim 1, characterized in that: The width of the groove (110) is L11, the shortest distance from the edge of the circular hole (100) to the edge of the shell (1) is L10, and the width of the groove (110) and the shortest distance from the edge of the circular hole (100) to the edge of the shell (1) satisfy: L11 / L10=8%-14%.

3. The cylindrical secondary battery as described in claim 2, characterized in that: The shortest distance from the edge of the circular hole (100) to the edge of the groove (110) is L12, and the shortest distance from the edge of the circular hole (100) to the edge of the groove (110) and the shortest distance from the edge of the circular hole (100) to the edge of the shell (1) satisfy: L12 / L10=17%-25%.

4. The cylindrical secondary battery as described in claim 2, characterized in that: The radius of the shell (1) is R1, and the shortest distance from the edge of the circular hole (100) to the edge of the shell (1) satisfies the following condition with respect to the radius of the shell (1): L10 / R1=60%-70%.

5. The cylindrical secondary battery as described in claim 1, characterized in that: The height of the pole post (2) is H10, and the thickness of the shell (1) and the height of the pole post (2) satisfy the following relationship: H11 / H10=13%-24%.

6. The cylindrical secondary battery as described in claim 1, characterized in that: The pole post (2) includes an upper end (21), a connecting part (22), and a lower end (23), wherein, The upper end (21) is located outside the shell (1), and the diameter of the upper end (21) is L50; The lower end (23) is located inside the shell (1), and the diameter of the lower end (23) is L52; The two ends of the connecting part (22) pass through the round hole (100) and are fixedly connected to the upper end (21) and the lower end (23), and the diameter of the connecting part (22) is L51; The two end faces of the lower plastic (3) abut against the lower end (23) and the inner wall of the shell (1), respectively; The sealing ring (5) is sleeved on the outside of the connecting part (22), and its lower end face abuts against the lower end face (23), and its upper end face abuts against the inner wall of the shell (1); The upper plastic (4) is sleeved on the outside of the connecting part (22), and both sides abut against the upper end (21) and the shell (1) respectively.

7. The cylindrical secondary battery as described in claim 6, characterized in that: The diameter of the shell (1) is D1, and the diameter of the lower end (23) satisfies the following relationship with the diameter of the shell (1): L52 / D1=52%-61%.

8. The cylindrical secondary battery as described in claim 6, characterized in that: The diameter of the connecting part (22) and the diameter of the lower end (23) satisfy the following condition: L51 / L52=50%-65%.

9. The cylindrical secondary battery as described in claim 6, characterized in that: The diameter of the upper end (21) and the diameter of the lower end (23) satisfy the following condition: L50 / L52=94.6%-98.5%.

10. The cylindrical secondary battery as described in claim 1, characterized in that: The number of grooves (110) is multiple, and the multiple grooves (110) are evenly distributed in a ring along the center of the circular hole (100), and the grooves (110) are arranged in an arc shape, with the arc A of the grooves (110) being 20-60°.

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