Cylindrical battery, method of manufacturing the same, battery module, and electric device

Abstract

The application discloses a cylindrical battery, a manufacturing method thereof, a battery module and a power utilization device. The cylindrical battery comprises an electrode assembly, a shell and an end cover assembly. The shell comprises a bottom wall and an opening, and the opening is arranged opposite to the bottom wall along an axial direction of the cylindrical battery. The end cover assembly is insulatedly connected with the shell and seals the opening, and the end cover assembly and the shell form an accommodating cavity. The electrode assembly is arranged in the accommodating cavity. The bottom wall has a bottom surface on a side away from the accommodating cavity along the axial direction. The radius of the cylindrical battery is R mm. A reference plane perpendicular to the axial direction and passing through a reference point on the bottom surface is defined. The distance between the reference point and the center axis of the cylindrical battery in the radial direction of the cylindrical battery is (R-2) mm. In the axial direction, the distance between the point farthest from the reference plane of the bottom surface and the reference plane is H mm, 0≤H / (R-2)≤0.014, and 15≤R≤60.

Description

Technical Field

[0001] This application relates to the field of batteries, and in particular to a cylindrical battery and its manufacturing method, battery module, and electrical equipment. Background Technology

[0002] With the rapid development of the new energy industry, the application of rechargeable batteries in electric vehicles, electric bicycles, power tools, and other fields is becoming a trend. Cylindrical batteries, due to their advantages such as good packability and high stability, are highly favored and are gradually being used in various complex scenarios.

[0003] Improving the reliability of cylindrical batteries has become a research focus for industry professionals. Summary of the Invention

[0004] This application provides a cylindrical battery, a method for manufacturing the same, a battery module, and an electrical device, which can improve the reliability of use.

[0005] In a first aspect, this application provides a cylindrical battery, comprising an electrode assembly, a housing, and an end cap assembly. The housing includes a bottom wall and an opening, the opening and the bottom wall being disposed opposite each other along the axial direction of the cylindrical battery. The end cap assembly is insulated from the housing and closes the opening, the end cap assembly and the housing forming a receiving cavity. The electrode assembly is disposed in the receiving cavity. The bottom wall has a bottom surface on the side axially away from the receiving cavity. The radius of the cylindrical battery is R mm. A reference plane is defined passing through a reference point on the bottom surface and perpendicular to the axial direction. The distance between the reference point and the central axis of the cylindrical battery in the radial direction is (R-2) mm. In the axial direction, the distance between the point on the bottom surface farthest from the reference plane and the reference plane is H mm, 0≤H / (R-2)≤0.014, 15≤R≤60.

[0006] In this embodiment, setting R to be greater than or equal to 15 is beneficial for increasing the capacity of a single cylindrical battery, reducing the number of cylindrical batteries in the battery module, improving energy density, and simplifying the structure of the battery module. Setting R to less than or equal to 60 in this embodiment can reduce the area of ​​the bottom wall, reduce the impact on the bottom wall stiffness, and reduce the deformation of the bottom wall under the internal air pressure of the cylindrical battery. Setting H / (R-2) to less than or equal to 0.014 in this embodiment can reduce the bulging deformation of the bottom wall, which is beneficial for reducing the overall height of the cylindrical battery, reducing the risk of poor welding between the bottom wall and the busbar, and improving the reliability of the cylindrical battery.

[0007] In one or more of the above optional embodiments, 0.0008 ≤ H / (R-2) ≤ 0.007. In this embodiment, setting H / (R-2) to be greater than or equal to 0.0008 causes the bottom wall to bulge and form an arched structure. This helps to disperse the stress on the bottom wall, increase its rigidity, reduce deformation during the cycling process of the cylindrical battery, lower the risk of bottom wall breakage, and improve the reliability of the cylindrical battery. Setting H / (R-2) to be less than or equal to 0.007 in this embodiment helps to reduce the overall height of the cylindrical battery, lower the risk of poor welding between the bottom wall and the busbar, and improve the reliability of the cylindrical battery.

[0008] In one or more of the above optional embodiments, 0 < H ≤ 0.8; optionally, 0 < H ≤ 0.3. In this embodiment, setting H to be greater than 0 causes the bottom wall to bulge and form an arched structure, which helps to disperse the stress on the bottom wall, increase its rigidity, reduce deformation during the cycling process of the cylindrical battery, reduce the risk of bottom wall breakage, and improve the reliability of the cylindrical battery. In this embodiment, setting H to be less than or equal to 0.8 helps to reduce the overall height of the cylindrical battery, reduce the risk of poor welding between the bottom wall and the busbar, and improve the reliability of the cylindrical battery.

[0009] In one or more of the above optional embodiments, 25 ≤ R ≤ 45. In this embodiment, R is set to be greater than or equal to 25, further increasing the capacity of a single cylindrical battery, reducing the number of cylindrical batteries in the battery module, improving energy density, and simplifying the structure of the battery module. In this embodiment, setting R to be less than or equal to 45 can reduce the area of ​​the bottom wall, reduce the impact on the bottom wall stiffness, and reduce bottom wall deformation.

[0010] In one or more of the above optional embodiments, the axial dimension of the cylindrical battery is 20mm-250mm. In this embodiment, setting the axial dimension L of the cylindrical battery to be greater than or equal to 20mm is beneficial for increasing the capacity of a single cylindrical battery, reducing the number of cylindrical batteries in the battery module, improving energy density, and simplifying the structure of the battery module. Setting the axial dimension L of the cylindrical battery to be less than or equal to 250mm in this embodiment is beneficial for shortening the conductive path of the positive and negative electrodes, reducing internal resistance, improving the vibration resistance of the cylindrical battery, and improving the cycle life and reliability of the cylindrical battery. Setting the axial dimension L of the cylindrical battery to be less than or equal to 250mm in this embodiment also helps to shorten the venting path during the formation process, reduce the gas remaining in the cylindrical battery, lower the internal pressure of the cylindrical battery, and reduce the deformation of the bottom wall.

[0011] In one or more of the above optional embodiments, the casing material includes steel, and the thickness of the bottom wall is 0.2mm-1mm; optionally, the thickness of the bottom wall is 0.4mm-0.8mm. In this embodiment, setting the bottom wall thickness to be greater than or equal to 0.2mm is beneficial for increasing the bottom wall's resistance to deformation, reducing the degree of bottom wall protrusion, lowering the risk of poor welding between the bottom wall and the busbar, and improving the reliability of the cylindrical battery. In this embodiment, setting the bottom wall thickness to be less than or equal to 1mm is beneficial for reducing the space and weight occupied by the bottom wall and increasing the energy density of the cylindrical battery.

[0012] In one or more of the above optional embodiments, the tensile strength of the bottom wall is 350MPa-500MPa. In this embodiment, setting the tensile strength of the bottom wall to greater than or equal to 350MPa helps reduce the bulging deformation of the bottom wall and the overall height of the cylindrical battery, reducing the risk of poor welding between the bottom wall and the busbar, and improving the reliability of the cylindrical battery. In this embodiment, setting the tensile strength of the bottom wall to less than or equal to 500MPa helps reduce the difficulty of shell stretching and forming, reduces the brittleness of the bottom wall, and reduces the risk of the bottom wall cracking when the cylindrical battery is subjected to external impact.

[0013] In one or more of the above optional embodiments, the Vickers hardness of the bottom wall is 160 HV-180 HV. In this embodiment, setting the Vickers hardness of the bottom wall to greater than or equal to 160 HV is beneficial for reducing wear on the bottom wall during the production, transportation, and use of the cylindrical battery, improving reliability, and also for increasing the compressive strength of the bottom wall and reducing bulging deformation of the bottom wall under the internal gas pressure of the cylindrical battery. In this embodiment, setting the Vickers hardness of the bottom wall to less than or equal to 180 HV is beneficial for reducing stress concentration on the bottom wall, reducing the risk of microcracks in the bottom wall, and improving the reliability of the cylindrical battery.

[0014] In one or more of the above optional embodiments, neither the end cap assembly nor the housing is provided with an injection hole for injecting electrolyte. In this embodiment, the electrolyte can be injected into the housing before the end cap assembly and housing are assembled; correspondingly, this embodiment does not require an injection hole on the end cap assembly and housing, which helps to simplify the structure of the cylindrical battery and saves the sealing process of the injection hole.

[0015] In one or more of the above optional embodiments, the housing further includes a sidewall, which includes a sidewall body and a transition wall. The sidewall body surrounds the electrode assembly, and the transition wall surrounds the bottom wall and is bent relative to the bottom wall. The transition wall connects the sidewall body and the bottom wall. An opening is defined at the end of the sidewall away from the bottom wall, and the thickness of the bottom wall is greater than the thickness of the sidewall body. Compared to the sidewall, the bottom wall has a larger thickness, which is beneficial for increasing the bottom wall's resistance to deformation, reducing the degree of bottom wall protrusion, reducing the risk of poor welding between the bottom wall and the busbar, and improving the reliability of the cylindrical battery. Compared to the bottom wall, the sidewall body has a smaller thickness, which is beneficial for reducing the space and weight occupied by the sidewall and increasing the energy density of the cylindrical battery.

[0016] In one or more of the above optional embodiments, the housing includes a sidewall connected to the bottom wall and surrounding the electrode assembly. The sidewall has a flange at its end away from the bottom wall, defining an opening. Axially, at least a portion of the flange is located on the side of the end cap assembly away from the electrode assembly. The flange is configured to be shaped by folding the sidewall after the cylindrical battery has been formed. During the formation of the cylindrical battery, gases are generated, increasing the internal pressure of the cylindrical battery, which can lead to the risk of bottom wall deformation. In this embodiment, the flange is shaped after the cylindrical battery has been formed, so that the flange applies pressure to the end cap assembly to achieve a seal between the housing and the end cap assembly. During the formation of the cylindrical battery, because the flange is not fully shaped, the housing and end cap assembly are not completely sealed, and the gases generated during formation escape through the gap between the end cap assembly and the housing, which helps to reduce the internal pressure of the cylindrical battery and reduce the bulging deformation of the bottom wall.

[0017] In one or more of the above optional embodiments, the internal pressure of the receiving cavity is 0.1 MPa - 0.17 MPa. In this embodiment, setting the internal pressure of the receiving cavity to less than or equal to 0.17 MPa helps reduce the bulging deformation of the bottom wall under the action of internal pressure, reduces the risk of poor welding between the bottom wall and the busbar, and improves the reliability of the cylindrical battery. Setting the internal pressure of the receiving cavity to greater than or equal to 0.1 MPa in this embodiment, on the one hand, facilitates the entry of electrolyte into the pores of the electrode, and on the other hand, helps support the casing, reducing the risk of the casing collapsing under external environmental pressure fluctuations.

[0018] Secondly, this application provides a method for manufacturing a cylindrical battery, which is used to manufacture the cylindrical battery provided in any embodiment of the first aspect. The manufacturing method includes: A housing is provided, the housing including sidewalls and a bottom wall connected to the sidewalls, the end of the sidewalls away from the bottom wall forming an opening; An electrode assembly is provided, comprising a first electrode tab and a second electrode tab with opposite polarities, the first electrode tab and the second electrode tab being located at opposite ends of the electrode assembly; Provide end cap assemblies; The electrode assembly is placed inside the housing, and the sidewall is rolled from the outside to deform the sidewall inward and form a protrusion. The protrusion is located on the side of the electrode assembly away from the bottom wall, and the sidewall includes a sidewall body connected to the protrusion and surrounding the electrode assembly. Connect the first electrode tab to the bottom wall; Connect the second electrode tab to the end cap assembly; Electrolyte is injected into the casing through the opening; The end cap assembly is placed onto the protrusion through the opening, and the end of the side wall away from the bottom wall is bent to form a flange in the first state, the flange constraining the end cap assembly in the axial direction. Connect the bottom wall and end cap assemblies to an external power source for formation; After the transformation is completed, the flange in the first form is bent into the second form to seal the opening. The bending angle of the flange in the second form relative to the main body of the side wall is greater than the bending angle of the flange in the first form relative to the main body of the side wall.

[0019] In the first configuration, the bending angle of the flange relative to the main sidewall is small, and the axial overlap area between the flange and the end cap assembly is also small. The main function of the flange in the first configuration is to constrain the end cap assembly, reducing the risk of the end cap assembly detaching from the casing during formation. The flange in the first configuration exerts less pressure on the end cap assembly, resulting in lower airtightness between the casing and the end cap assembly. Gas generated during formation is discharged through the gap between the end cap assembly and the casing, thereby reducing the internal pressure of the cylindrical battery. After formation, the flange is bent again to increase the bending angle of the flange relative to the main sidewall, increasing the axial pressure exerted by the flange on the end cap assembly to achieve a seal between the casing and the end cap assembly, improving the reliability of the cylindrical battery. The manufacturing method of this embodiment can reduce the internal pressure of the cylindrical battery and the bulging deformation of the bottom wall, improving the reliability of the cylindrical battery.

[0020] Thirdly, this application provides a battery module, which includes a cylindrical battery provided in any embodiment of the first aspect or a cylindrical battery manufactured according to the manufacturing method of the second aspect.

[0021] Fourthly, this application provides an electrical device that includes a battery module according to any embodiment of the third aspect. Attached Figure Description

[0022] The features, advantages, and technical effects of exemplary embodiments of this application will now be described with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the structure of a cylindrical battery provided in some embodiments of this application; Figure 2 for Figure 1 A schematic diagram of the explosion of the cylindrical battery shown; Figure 3 for Figure 1 A cross-sectional schematic diagram of the cylindrical battery shown; Figure 4 for Figure 3 Enlarged view of point A in the circle; Figure 5 for Figure 3 Enlarged view of point B in the circle; Figure 6 This is a partial schematic diagram of the manufacturing process of a cylindrical battery provided in some embodiments of this application; Figure 7 This is another partial schematic diagram of the manufacturing process of a cylindrical battery provided in some embodiments of this application; Figure 8 A schematic diagram of the electrode assembly of a cylindrical battery provided in some embodiments of this application; Figure 9 A schematic diagram of a cylindrical battery provided in some embodiments of this application; Figure 10 for Figure 9 Enlarged illustration within the box; Figure 11 This is a schematic diagram of the structure of a battery module provided in some embodiments of this application; Figure 12 The diagram shows the structure of electrical equipment provided in some embodiments of this application.

[0024] The annotations in the attached figures are explained as follows: 1. Cylindrical batteries; 1000. Battery modules; 2000. Electrical equipment; 10. Electrode assembly; 11. First electrode tab; 12. Second electrode tab; 20. Shell; 20a. Opening; 21. Bottom wall; 211. Bottom surface; 22. Side wall; 221. Side wall body; 222. Transition wall; 223. Protrusion; 224. Limiting part; 225. Flanged edge; 226. Recess; 30. End cap assembly; 31. End cap; 32. Insulation structure; 33. Explosion-proof sheet; 34. Orifice plate; 40. Receiving cavity; 50. First flow collector; 60. Second flow collector; C, central axis; P, reference point; S, reference plane; Z, axis. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0026] The terms "first," "second," "third," etc., used in the specification, claims, or accompanying drawings of this application are used to distinguish different objects, not to describe a specific order or hierarchy. In the embodiments of this application, the same reference numerals denote the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0027] In this application, the reference to "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment that is mutually exclusive with other embodiments.

[0028] In the description of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0029] In the embodiments of this application, "parallel" includes not only the case of absolute parallelism, but also the case of approximate parallelism as commonly understood in engineering; similarly, "perpendicular" also includes not only the case of absolute perpendicularity, but also the case of approximate perpendicularity as commonly understood in engineering. For example, if the angle between two directions is 80°-90°, the two directions can be considered perpendicular; if the angle between two directions is 0°-10°, the two directions can be considered parallel.

[0030] The cylindrical battery of this application is described below with reference to the accompanying drawings.

[0031] Reference Figures 1 to 10 This application provides a cylindrical battery 1, which can be a lithium-ion battery, sodium-lithium-ion battery, sodium-ion battery, magnesium-ion battery, or other types of battery. After discharge, the secondary battery can be recharged to activate the active materials and continue to be used.

[0032] In some embodiments, the cylindrical battery 1 includes an electrode assembly 10, a housing 20, and an end cap assembly 30. The housing 20 has an opening 20a, and the end cap assembly 30 is connected to the housing 20 and closes the opening 20a. The end cap assembly 30 and the housing 20 together form a receiving cavity 40. The electrode assembly 10 is disposed in the receiving cavity 40.

[0033] In some embodiments, the electrode assembly 10 includes a positive electrode, a negative electrode, and a separator, with the separator disposed between the positive and negative electrode. As an example, an electrode assembly 10 is formed by winding a separator, a positive electrode, another separator, and a negative electrode.

[0034] During the charging and discharging process of cylindrical battery 1, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrode plates. A separator insulates the positive and negative electrode plates. The separator reduces the risk of short circuits occurring between the positive and negative electrode plates while allowing active ions to pass through.

[0035] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer. The positive electrode current collector includes a positive electrode coated area with the positive electrode active material layer and a positive electrode empty foil area without the positive electrode active material layer. The positive electrode coated area and the positive electrode empty foil area can be arranged along the axial direction Z of the cylindrical battery 1.

[0036] In some embodiments, the positive electrode empty foil region is wound into multiple turns.

[0037] In some embodiments, the positive electrode sheet includes a positive tab, which can be formed by flattening or smoothing the positive electrode empty foil area. Exemplarily, the positive electrode empty foil area can be pressed from the outside to the inside along the radial direction of the electrode assembly 10, and the end of the positive electrode empty foil area away from the positive electrode coating area is bent to form the positive tab.

[0038] In other embodiments, the positive electrode tab can be formed by flattening the positive electrode empty foil area. Exemplarily, the positive electrode empty foil area is pressed in the axial direction Z of the electrode assembly 10 from the side of the positive electrode empty foil area away from the positive electrode coating area, and the end of the positive electrode empty foil area away from the positive electrode coating area is bent (for example, it can be bent toward or away from the central axis C of the cylindrical battery 1) to form the positive electrode tab.

[0039] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. The negative electrode current collector includes a negative electrode coated area coated with the negative electrode active material layer and a negative electrode empty foil area uncoated with the negative electrode active material layer. The negative electrode coated area and the negative electrode empty foil area can be arranged along the axial direction Z of the cylindrical battery 1.

[0040] In some embodiments, the negative electrode empty foil region is wound into multiple turns.

[0041] In some embodiments, the negative electrode sheet includes a negative electrode tab, which can be formed by kneading, smoothing or flattening the negative electrode empty foil area.

[0042] In some embodiments, along the axial direction Z of the cylindrical battery 1, the positive tab and the negative tab are located at both ends of the electrode assembly 10, respectively.

[0043] In some embodiments, the housing 20 includes a bottom wall 21 and a side wall 22. An opening 20a is disposed opposite to the bottom wall 21 along the axial direction Z of the cylindrical battery 1. The side wall 22 is connected to the bottom wall 21, and one end of the side wall 22 away from the bottom wall 21 defines the opening 20a. The bottom wall 21 and the end cap assembly 30 are arranged along the axial direction Z. The side wall 22 is connected to the end cap assembly 30.

[0044] The bottom wall 21 and the side wall 22 can be integrally formed. Alternatively, the bottom wall 21 and the side wall 22 can also be formed independently and connected by welding, gluing or other means.

[0045] In some embodiments, the housing 20 is insulated from the end cap assembly 30. Specifically, the sidewall 22 is insulated from the end cap assembly 30.

[0046] In some embodiments, the end cap assembly 30 includes an end cap 31 and an insulating structure 32 disposed between the end cap 31 and the sidewall 22.

[0047] For example, the insulating structure 32 surrounds the end cap 31.

[0048] For example, the insulating structure 32 may be insulating rubber or ceramic.

[0049] In some embodiments, the electrode assembly 10 includes a positive electrode and a negative electrode. One of the positive electrode and the negative electrode is connected to the end cap 31, and the other is connected to the bottom wall 21. The end cap 31 and the bottom wall 21 can serve as two electrode terminals of the cylindrical battery 1.

[0050] In some embodiments, the end cap assembly 30 includes a blast-proof plate 33 connected to the end cap 31. As an example, the blast-proof plate 33 may be connected to the end cap 31 by welding, riveting, bonding, or other suitable means.

[0051] When the internal pressure of the cylindrical battery 1 exceeds the upper limit that the explosion-proof plate 33 can withstand, the internal pressure of the cylindrical battery 1 can cause the explosion-proof plate 33 to flip and explode in the direction away from the electrode assembly 10, thereby achieving the purpose of power cut-off and pressure relief. This helps to reduce the risk of the cylindrical battery 1 exploding due to excessive internal pressure and improves the safety performance of the cylindrical battery 1.

[0052] In some embodiments, at least a portion of the explosion-proof plate 33 is located between the end cap 31 and the electrode assembly 10. In the axial direction Z, the end cap 31 provides a restraining effect on the explosion-proof plate 33, which helps to reduce the risk of the explosion-proof plate 33 not releasing pressure in a timely manner due to excessive overturning stroke.

[0053] In some embodiments, a portion of the explosion-proof sheet 33 is located between the end cap 31 and the electrode assembly 10, and another portion of the explosion-proof sheet 33 is bent outward toward the end cap 31 away from the electrode assembly 10 to cover the edge of the end cap 31. Optionally, an insulating structure 32 is disposed between the explosion-proof sheet 33 and the sidewall 22.

[0054] In some embodiments, the explosion-proof plate 33 is provided with a first notch. The first notch is a line mark formed on the explosion-proof plate 33 using a tool such as a cutting tool or a stamping process, and is thinner than other areas. The first notch may be formed on the side of the explosion-proof plate 33 facing the electrode assembly 10, or it may be formed on the side of the explosion-proof plate 33 facing the end cap 31.

[0055] By setting a first notch on the explosion-proof sheet 33, a weak part corresponding to the first notch can be formed in the explosion-proof sheet 33. The thickness of the weak part is less than the thickness of other parts of the explosion-proof sheet 33. When the internal gas pressure of the cylindrical battery 1 is too high, the weak part is easy to break under the action of gas pressure, which helps to reduce the difficulty of the explosion-proof sheet 33 flipping and exploding under the action of gas pressure.

[0056] In some embodiments, the end cap assembly 30 includes a perforated plate 34 disposed between the explosion-proof sheet 33 and the electrode assembly 10 along the axial Z direction of the cylindrical battery 1. The perforated plate 34 connects the electrode assembly 10 and the explosion-proof sheet 33.

[0057] For example, the orifice plate 34 is electrically connected to the positive or negative tab of the electrode assembly 10.

[0058] When the internal pressure of the cylindrical battery 1 reaches the voltage-breaking pressure value of the orifice plate 34, the explosion-proof plate 33 flips towards the end cover 31, and the orifice plate 34 is broken as the explosion-proof plate 33 flips, thereby disconnecting the current circuit and realizing power-off protection. The voltage-breaking pressure value of the orifice plate 34 refers to the internal pressure of the cylindrical battery 1 when the explosion-proof plate 33 flips and the orifice plate 34 breaks, thus disconnecting the current circuit.

[0059] In some embodiments, the perforated plate 34 is provided with a second notch. By providing the second notch, the local strength of the perforated plate 34 can be reduced, which is beneficial for the perforated plate 34 to break when the internal pressure of the cylindrical battery 1 reaches the voltage-breaking force value of the perforated plate 34.

[0060] In some embodiments, the perforated plate 34 is provided with through holes. There may be one or more through holes. The through holes may be round, rectangular, elliptical, fan-shaped, oblong, or other shapes. The through holes serve as channels for gas flow. The gas inside the cylindrical battery 1 acts on the explosion-proof plate 33 through the through holes, which helps to reduce the risk of the cylindrical battery 1 exploding due to excessive internal gas pressure.

[0061] In some embodiments, the cylindrical battery 1 includes a first current collector 50 and a second current collector 60. The second current collector 60 is disposed between the orifice plate 34 and the electrode assembly 10, and is connected to the orifice plate 34 and the electrode assembly 10. The first current collector 50 is disposed between the bottom wall 21 and the electrode assembly 10, and is connected to the bottom wall 21 and the electrode assembly 10. For example, the second current collector 60 is welded to the orifice plate 34, and the first current collector 50 is welded to the bottom wall 21.

[0062] In some embodiments, one of the second current collector 60 and the first current collector 50 is connected to the positive electrode tab, and the other is connected to the negative electrode tab.

[0063] For example, the second current collector 60 is connected to the positive electrode tab, and the end cap 31 is electrically connected to the positive electrode tab in sequence via the explosion-proof plate 33, the perforated plate 34, and the second current collector 60. The first current collector 50 is connected to the negative electrode tab. The end cap 31 and the bottom wall 21 serve as the positive and negative electrodes of the cylindrical battery 1, respectively.

[0064] In some embodiments, the second current collector 60 is bent into a multi-layered structure. For example, the second current collector 60 is bent into three layers.

[0065] In some embodiments, the bottom wall 21 has a bottom surface 211 on the side away from the receiving cavity 40 along the axial direction Z. The radius of the cylindrical battery 1 is R mm. A reference plane S is defined that passes through a reference point P on the bottom surface 211 and is perpendicular to the axial direction Z. The distance between the reference point P and the central axis C of the cylindrical battery 1 in the radial direction is (R-2) mm. In the axial direction Z, the distance between the point on the bottom surface 211 farthest from the reference plane S and the reference plane S is H mm, 0≤H / (R-2)≤0.014, 15≤R≤60.

[0066] For example, R is 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, or any value between two of these.

[0067] For example, H / (R-2) is 0, 0.0002, 0.0005, 0.0007, 0.0008, 0.001, 0.0011, 0.0012, 0.0013, 0.0014, 0.0015, 0.0017, 0.002, 0.0025, 0.003, 0.0033, 0.0035, 0.0038, 0.004, 0.0045 0.005, 0.0055, 0.006, 0.0065, 0.007, 0.0075, 0.008, 0.0085, 0.009, 0.0095, 0.01, 0.0105, 0.011, 0.0115, 0.012, 0.0125, 0.013, 0.0135, 0.0138, 0.014, or any value between any two of these.

[0068] It should be noted that the reference plane S is a virtual plane and the central axis C is a virtual line. They are introduced here only to facilitate the explanation of the degree of protrusion of the bottom surface 211.

[0069] On the bottom surface 211, there may be multiple points on the radial direction of the cylindrical battery 1 with a distance of (R-2) from the central axis C of the cylindrical battery 1; among these multiple points, any one point can be selected as the reference point P.

[0070] H is greater than or equal to 0. In some examples, H may be equal to 0, the bottom surface 211 is a plane, and the bottom surface 211 lies within the reference plane S. In other examples, H may be greater than 0, at least a portion of the bottom surface 211 is a convex surface, which protrudes from the reference plane S in the direction from the end cap assembly 30 to the bottom wall 21.

[0071] In this embodiment, setting R to be greater than or equal to 15 is beneficial for increasing the capacity of a single cylindrical battery 1, reducing the number of cylindrical batteries 1 in the battery module, improving energy density, and simplifying the structure of the battery module. Setting R to be less than or equal to 60 in this embodiment can reduce the area of ​​the bottom wall 21, reduce the impact on the stiffness of the bottom wall 21, and reduce the deformation of the bottom wall 21 under the internal air pressure of the cylindrical battery 1. Setting H / (R-2) to be less than or equal to 0.014 in this embodiment can reduce the bulging deformation of the bottom wall 21, which is beneficial for reducing the overall height of the cylindrical battery 1, reducing the risk of poor welding between the bottom wall 21 and the busbar, and improving the reliability of the cylindrical battery 1.

[0072] In some embodiments, 0.0008 ≤ H / (R-2) ≤ 0.007. In this embodiment, setting H / (R-2) to be greater than or equal to 0.0008 causes the bottom wall 21 to bulge and form an arched structure. This helps to disperse the stress on the bottom wall 21, increase its rigidity, reduce deformation during the cycling process of the cylindrical battery 1, lower the risk of breakage, and improve the reliability of the cylindrical battery 1. Setting H / (R-2) to be less than or equal to 0.007 in this embodiment also helps to reduce the overall height of the cylindrical battery 1, lower the risk of poor welding between the bottom wall 21 and the busbar, and improve the reliability of the cylindrical battery 1.

[0073] In some embodiments, 0 < H ≤ 0.8.

[0074] For example, H is 0.001, 0.003, 0.005, 0.008, 0.01, 0.012, 0.015, 0.018, 0.02, 0.025, 0.03, 0.035, 0.04, 0.045, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, or any value between two of these.

[0075] In this embodiment, setting H to be greater than 0 causes the bottom wall 21 to bulge and form an arched structure. This helps to disperse the stress on the bottom wall 21, increase its rigidity, reduce its deformation during the cycling process of the cylindrical battery 1, lower the risk of breakage, and improve the reliability of the cylindrical battery 1. Setting H to be less than or equal to 0.8 in this embodiment helps to reduce the overall height of the cylindrical battery 1, lower the risk of poor welding between the bottom wall 21 and the busbar, and improve the reliability of the cylindrical battery 1.

[0076] In some embodiments, 0 < H ≤ 0.3, which helps to reduce the overall height of the cylindrical battery 1, reduce the risk of poor welding between the bottom wall 21 and the busbar, and improve the reliability of the cylindrical battery 1.

[0077] In some embodiments, 25 ≤ R ≤ 45. As an example, R is any value between 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, or any two of these.

[0078] In this embodiment, R is set to be greater than or equal to 25, which further increases the capacity of a single cylindrical battery 1, reduces the number of cylindrical batteries 1 in the battery module, improves energy density, and simplifies the structure of the battery module. In this embodiment, R is set to be less than or equal to 45, which can reduce the area of ​​the bottom wall 21, reduce the impact on the stiffness of the bottom wall 21, and reduce the deformation of the bottom wall 21.

[0079] In some embodiments, the dimension L of the cylindrical battery 1 along the axial direction Z is 20mm-250mm.

[0080] As an example, L is 20mm, 22mm, 24mm, 25mm, 26mm, 28mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, 70mm, 75mm, 80mm, 85mm, 90mm, 95mm, 100mm, 110mm, 120mm, 130mm, 140mm, 150mm, 160mm, 170mm, 180mm, 190mm, 200mm, 210mm, 220mm, 230mm, 240mm, 250mm, or any value between two of these.

[0081] For example, the dimension L of the cylindrical battery 1 along the axial direction Z can be equal to the distance from the bottom surface 211 of the bottom wall 21 of the housing 20 along the axial direction Z to the top surface of the end cap 31.

[0082] In this embodiment, the dimension L along the Z-axis of the cylindrical battery 1 is set to be greater than or equal to 20 mm. This is beneficial for increasing the capacity of a single cylindrical battery 1, reducing the number of cylindrical batteries 1 in the battery module, improving energy density, and simplifying the structure of the battery module. In this embodiment, the dimension L along the Z-axis of the cylindrical battery 1 is set to be less than or equal to 250 mm. This is beneficial for shortening the conductive path of the positive and negative electrodes, reducing internal resistance, improving the vibration resistance of the cylindrical battery 1, and improving the cycle life and reliability of the cylindrical battery 1. Furthermore, setting the dimension L along the Z-axis of the cylindrical battery 1 to be less than or equal to 250 mm also helps to shorten the venting path during the formation process, reduce the gas remaining in the cylindrical battery 1, lower the internal pressure of the cylindrical battery 1, and reduce the deformation of the bottom wall 21.

[0083] In some embodiments, L is 65mm-150mm.

[0084] In some embodiments, the material of the housing 20 includes steel.

[0085] As an example, the material of housing 20 includes carbon steel or stainless steel.

[0086] The steel casing 20 has high mechanical strength and good rigidity. During the cycling process of the cylindrical battery 1, the steel casing 20 is not easily deformed, which helps to constrain the expansion of the electrode assembly 10, reduce the misalignment between the positive and negative electrode plates, and improve the cycle performance and life of the cylindrical battery 1.

[0087] In some embodiments, the housing 20 is made of carbon steel. Compared to stainless steel, carbon steel has advantages such as good plasticity, ease of forming, and high electrical conductivity.

[0088] In some embodiments, the housing 20 is made of nickel-plated carbon steel.

[0089] In some embodiments, the thickness t1 of the bottom wall 21 is 0.2 mm to 1 mm. As an example, t1 is 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, or any value between any two of these.

[0090] In this embodiment, the thickness t1 of the bottom wall 21 is set to be greater than or equal to 0.2 mm, which helps to increase the deformation resistance of the bottom wall 21, reduce the degree of protrusion of the bottom wall 21, reduce the risk of poor welding between the bottom wall 21 and the busbar, and improve the reliability of the cylindrical battery 1. In this embodiment, the thickness t1 of the bottom wall 21 is set to be less than or equal to 1 mm, which helps to reduce the space and weight occupied by the bottom wall 21 and increase the energy density of the cylindrical battery 1.

[0091] In some embodiments, the thickness t1 of the bottom wall 21 is 0.4mm-0.8mm, which is beneficial to balancing the reliability and energy density of the cylindrical battery 1.

[0092] In some embodiments, the tensile strength of the bottom wall 21 is 350 MPa-500 MPa. As an example, the tensile strength of the bottom wall 21 is 350 MPa, 360 MPa, 370 MPa, 380 MPa, 390 MPa, 400 MPa, 410 MPa, 420 MPa, 430 MPa, 440 MPa, 450 MPa, 460 MPa, 470 MPa, 480 MPa, 490 MPa, 500 MPa, or any value between any two of these.

[0093] In this embodiment, the tensile strength of the bottom wall 21 is set to be greater than or equal to 350 MPa. This helps to reduce the bulging deformation of the bottom wall 21 and the overall height of the cylindrical battery 1, thereby reducing the risk of poor welding between the bottom wall 21 and the busbar and improving the reliability of the cylindrical battery 1. In this embodiment, the tensile strength of the bottom wall 21 is set to be less than or equal to 500 MPa. This helps to reduce the difficulty of stretching and forming the casing 20, reduce the brittleness of the bottom wall 21, and reduce the risk of the bottom wall 21 cracking when the cylindrical battery 1 is subjected to external impact.

[0094] In some embodiments, the Vickers hardness of the bottom wall 21 is 160 HV - 180 HV.

[0095] As an example, the Vickers hardness of the bottom wall 21 is 160HV, 161HV, 162HV, 163HV, 164HV, 165HV, 166HV, 167HV, 168HV, 169HV, 170HV, 171HV, 172HV, 173HV, 174HV, 175HV, 176HV, 177HV, 178HV, 179HV, 180HV, or any value between any two of these.

[0096] In this embodiment, the Vickers hardness of the bottom wall 21 is set to be greater than or equal to 160 HV. This helps reduce wear on the bottom wall 21 during the production, transportation, and use of the cylindrical battery 1, improving reliability. It also helps increase the compressive strength of the bottom wall 21 and reduce bulging deformation of the bottom wall 21 under the internal air pressure of the cylindrical battery 1. In this embodiment, the Vickers hardness of the bottom wall 21 is set to be less than or equal to 180 HV. This helps reduce stress concentration on the bottom wall 21, lowers the risk of microcracks in the bottom wall 21, and improves the reliability of the cylindrical battery 1.

[0097] In some embodiments, neither the end cap assembly 30 nor the housing 20 is provided with an injection port for injecting electrolyte.

[0098] In conventional cylindrical batteries, an injection hole is provided on the end cap assembly or the housing; after the end cap assembly and the housing are sealed and assembled, electrolyte can be injected into the housing through the injection hole.

[0099] In this embodiment, the electrolyte can be injected into the housing 20 before the end cap assembly 30 and the housing 20 are assembled. Correspondingly, this embodiment does not require the provision of an injection hole on the end cap assembly 30 and the housing 20, which helps to simplify the structure of the cylindrical battery 1 and saves the sealing process of the injection hole.

[0100] In some embodiments, the housing 20 further includes a sidewall 22, which includes a sidewall body 221 and a transition wall 222. The sidewall body 221 surrounds the electrode assembly 10, and the transition wall 222 surrounds the bottom wall 21 and is bent relative to the bottom wall 21. The transition wall 222 connects the sidewall body 221 and the bottom wall 21. One end of the sidewall 22 away from the bottom wall 21 defines an opening 20a. The thickness t1 of the bottom wall 21 is greater than the thickness t2 of the sidewall body 221.

[0101] As an example, the transition wall 222 is bent into an arc-shaped structure, thus forming a rounded corner surface.

[0102] Compared to the sidewall 22, the bottom wall 21 has a greater thickness, which helps to increase the deformation resistance of the bottom wall 21, reduce the degree of protrusion of the bottom wall 21, reduce the risk of poor welding between the bottom wall 21 and the busbar, and improve the reliability of the cylindrical battery 1. Compared to the bottom wall 21, the sidewall body 221 has a smaller thickness, which helps to reduce the space and weight occupied by the sidewall 22, and increase the energy density of the cylindrical battery 1.

[0103] In some embodiments, the thickness of the transition wall 222 at one end connected to the bottom wall 21 is greater than the thickness of the transition wall 222 at one end connected to the side wall body 221.

[0104] Optionally, the thickness of the transition wall 222 at the end connected to the bottom wall 21 is equal to the thickness of the bottom wall 21. The thickness of the transition wall 222 at the end connected to the side wall body 221 is equal to the thickness of the side wall body 221.

[0105] Optionally, the thickness of the transition wall 222 gradually decreases along the direction from the bottom wall 21 to the side wall body 221.

[0106] In this embodiment, the transition wall 222 has a varying thickness, which helps to achieve a smooth transition between the side wall body 221 and the bottom wall 21 and reduces stress concentration.

[0107] In some embodiments, the thickness t2 of the sidewall body 221 is 0.1 mm to 0.6 mm. As an example, t2 is 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, or any value between any two of these.

[0108] In some embodiments, the housing 20 includes a sidewall 22 connected to the bottom wall 21 and surrounding the electrode assembly 10. One end of the sidewall 22 away from the bottom wall 21 has a flange 225 defining an opening 20a. In the axial direction Z, at least a portion of the flange 225 is located on the side of the end cap assembly 30 away from the electrode assembly 10.

[0109] The flange 225 can constrain the end cap assembly 30 in the axial Z direction, thereby reducing the risk of the end cap assembly 30 detaching from the housing 20 during the cycling of the cylindrical battery 1.

[0110] In some embodiments, the sidewall 22 includes a protrusion 223 and a limiting portion 224. The sidewall body 221 and the limiting portion 224 are arranged along the axial direction Z. The protrusion 223 connects the sidewall body 221 and the limiting portion 224. The limiting portion 224 surrounds the end cap assembly 30. The protrusion 223 protrudes from the inner surface of the sidewall body 221 toward the electrode assembly 10. A flange 225 is connected to the end of the limiting portion 224 away from the protrusion 223 and is bent toward the central axis C relative to the limiting portion 224.

[0111] In the axial direction Z, a portion of the end cap assembly 30 is held between the protrusion 223 and the flange 225. The limiting portion 224 constrains the end cap assembly 30 in the radial direction of the cylindrical battery 1, and the protrusion 223 and the flange 225 constrain the end cap assembly 30 in the axial direction Z, thereby fixing the end cap assembly 30.

[0112] In some embodiments, the sidewall 22 is provided with a recess 226 that is recessed relative to the outer surface of the sidewall body 221, and the recess 226 corresponds to the position of the protrusion 223.

[0113] As an example, the sidewall 22 can be formed with recesses 226 and protrusions 223 by rolling it from the outside.

[0114] In some embodiments, the flange 225 is configured to be shaped by folding the sidewall 22 after the cylindrical battery 1 has been formed.

[0115] During the formation process of the cylindrical battery 1, gas is generated, which increases the internal pressure of the cylindrical battery 1. This increased internal pressure may cause deformation of the bottom wall 21. In this embodiment, the flange 225 is shaped after the cylindrical battery 1 is formed, so that the flange 225 applies pressure to the end cap assembly 30 to achieve a seal between the housing 20 and the end cap assembly 30. During the formation process of the cylindrical battery 1, since the flange 225 is not fully shaped, the housing 20 and the end cap assembly 30 are not completely sealed. The gas generated during formation is discharged through the gap between the end cap assembly 30 and the housing 20, which helps to reduce the internal pressure of the cylindrical battery 1 and reduce the bulging deformation of the bottom wall 21.

[0116] In some embodiments, the internal pressure of the receiving cavity 40 is 0.1 MPa - 0.17 MPa. The internal pressure of the receiving cavity 40 is the same as the internal pressure of the cylindrical battery 1.

[0117] As an example, the internal pressure of the receiving cavity 40 is 0.1 MPa, 0.11 MPa, 0.12 MPa, 0.13 MPa, 0.14 MPa, 0.15 MPa, 0.16 MPa, 0.17 MPa, or any value between any two of these.

[0118] In this embodiment, the internal pressure of the receiving cavity 40 is set to be less than or equal to 0.17 MPa. This helps to reduce the bulging deformation of the bottom wall 21 under the action of internal pressure, reduces the risk of poor welding between the bottom wall 21 and the busbar, and improves the reliability of the cylindrical battery 1. In this embodiment, the internal pressure of the receiving cavity 40 is set to be greater than or equal to 0.1 MPa. This helps the electrolyte enter the pores of the electrode and also helps to support the housing 20, reducing the risk of the housing 20 collapsing when the external environmental pressure fluctuates.

[0119] Secondly, this application also provides a method for manufacturing a cylindrical battery, which is used to manufacture the cylindrical battery 1 of any of the foregoing embodiments.

[0120] The manufacturing methods for cylindrical batteries include: S10: Provide a housing 20, the housing 20 including a side wall 22 and a bottom wall 21 connected to the side wall 22, and an opening 20a is formed at the end of the side wall 22 away from the bottom wall 21; S20: Provide an electrode assembly 10, which includes a first electrode tab 11 and a second electrode tab 12 with opposite polarities, the first electrode tab 11 and the second electrode tab 12 being located at opposite ends of the electrode assembly 10; S30: Provides end cap assembly 30; S40: The electrode assembly 10 is placed inside the housing 20, and the side wall 22 is rolled from the outside to deform the side wall 22 inward and form a protrusion 223. The protrusion 223 is located on the side of the electrode assembly 10 away from the bottom wall 21. The side wall 22 includes a side wall body 221 connected to the protrusion 223 and surrounding the electrode assembly 10. S50: Connect the first pole piece 11 to the bottom wall 21; S60: Connect the second electrode tab 12 to the end cap assembly 30; S70: Electrolyte is injected into the housing 20 through opening 20a; S80: Reference Figure 6 and Figure 7 The end cap assembly 30 is placed on the protrusion 223 through the opening 20a, and the end of the side wall 22 away from the bottom wall 21 is bent to form a flange 225 in the first state. The flange 225 constrains the end cap assembly 30 in the axial direction Z. S90: Connect the bottom wall 21 and end cap assembly 30 to an external power source for formation; S100: After transformation, bend the flange 225 in the first form into the second form (refer to...). Figure 4 To seal the opening 20a, the bending angle of the second type of flange 225 relative to the side wall body 221 is greater than that of the first type of flange 225 relative to the side wall body 221.

[0121] When assembling the cylindrical battery 1 based on the above-described cylindrical battery manufacturing method, it is not necessary to follow the above steps in sequence. That is, the steps can be performed in the order mentioned in the embodiments, or in a different order than that mentioned in the embodiments, or several steps can be performed simultaneously.

[0122] For example, the execution of S10, S20, and S30 can be performed in any order, and they can also be performed simultaneously. For example, the execution of S30 and S40 can be performed in any order, and they can also be performed simultaneously.

[0123] As an example, in step S80, the end of the sidewall 22 away from the bottom wall 21 is bent inward toward the central axis C of the cylindrical battery 1 by a first angle θ1; the first angle θ1 is the bending angle of the flange 225 of the first form relative to the sidewall body 221. A reference line is set parallel to the central axis C and passes through the outer surface of the sidewall body 221, and the angle between the flange 225 and the reference line is the first angle θ1.

[0124] As an example, in step S100, the flange 225 in the first form is further bent to form the flange 225 in the second form. The flange 225 in the second form is the flange 225 of the cylindrical battery 1 in the finished product state. The bending angle of the flange 225 in the second form relative to the side wall body 221 is a second angle θ2. Specifically, the angle between the flange 225 and the reference line is the second angle θ2, where θ2 is greater than θ1.

[0125] In its first configuration, the flange 225 has a smaller bending angle relative to the sidewall body 221, and the area of ​​overlap between the flange 225 and the end cap assembly 30 in the axial Z direction is also smaller. The main function of the flange 225 in its first configuration is to constrain the end cap assembly 30, reducing the risk of the end cap assembly 30 detaching from the housing 20 during the formation process. The flange 225 in its first configuration exerts less pressure on the end cap assembly 30, resulting in lower airtightness between the housing 20 and the end cap assembly 30. Gas generated during formation is discharged through the gap between the end cap assembly 30 and the housing 20, thereby reducing the internal pressure of the cylindrical battery 1. After formation, the flange 225 is bent again to increase the bending angle of the flange 225 relative to the sidewall body 221, increasing the pressure exerted by the flange 225 on the end cap assembly 30 in the axial Z direction, thereby achieving a seal between the housing 20 and the end cap assembly 30 and improving the reliability of the cylindrical battery 1. The manufacturing method of this embodiment can reduce the internal pressure of the cylindrical battery 1 and the bulging deformation of the bottom wall 21, thereby improving the reliability of the cylindrical battery 1.

[0126] In some embodiments, step S20 includes: S21: Provide an electrode assembly 10, which includes a first electrode tab 11 and a second electrode tab 12 with opposite polarities, the first electrode tab 11 and the second electrode tab 12 being located at opposite ends of the electrode assembly 10; S22: Weld the first current collector 50 to the first electrode 11, and weld the second current collector 60 to the second electrode 12.

[0127] In some embodiments, step S50 includes welding the bottom wall 21 to the first current collector 50 so that the first electrode tab 11 is connected to the bottom wall 21.

[0128] In some embodiments, step S60 includes welding the end cap assembly 30 to the second current collector 60 to connect the second tab 12 to the end cap assembly 30.

[0129] In some embodiments, the first angle θ1 is 10°-45°. As an example, the first angle θ1 is 10°, 12°, 15°, 18°, 20°, 22°, 25°, 28°, 30°, 32°, 35°, 38°, 40°, 42°, 45° or any value between any two of these.

[0130] In this embodiment, the first angle θ1 is set to be greater than or equal to 10° so that the flange 225 in the first state can constrain the end cap assembly 30, reducing the risk of the end cap assembly 30 coming off the housing 20 during the formation process; in this embodiment, the first angle θ1 is set to be less than or equal to 45° to reduce the pressure exerted by the flange 225 in the first state on the end cap assembly 30, reduce the airtightness between the housing 20 and the end cap assembly 30, and facilitate the discharge of gas generated during formation through the gap between the end cap assembly 30 and the housing 20, thereby reducing the internal pressure of the cylindrical battery 1.

[0131] In some embodiments, the second angle θ2 is 90°-110°. As an example, the second angle θ2 is 90°, 92°, 95°, 98°, 100°, 102°, 105°, 108°, 110°, or any value between any two of these. In this embodiment, after the flange 225 is shaped, the pressure applied by the flange 225 to the end cap assembly 30 in the axial Z direction can be increased to achieve a seal between the housing 20 and the end cap assembly 30, thereby improving the reliability of the cylindrical battery 1.

[0132] In some embodiments, the first electrode 11 is the negative electrode and the second electrode 12 is the positive electrode.

[0133] According to the third aspect of this application, referring to Figure 11 This application also provides a battery module 1000, which includes a plurality of cylindrical batteries 1 provided according to any embodiment of this application.

[0134] In some embodiments, the battery module 1000 further includes a plurality of busbars (not shown). The busbars connect to the cylindrical batteries 1. At least two cylindrical batteries 1 can be connected in series or in parallel via the busbars.

[0135] As an example, a busbar is welded to the bottom wall 21 of one cylindrical battery 1 and the end cap 31 of another cylindrical battery 1 to connect the two cylindrical batteries 1 in series.

[0136] According to the fourth aspect of this application, referring to Figure 12 This application also provides an electrical device 2000, which includes a battery module 1000 provided in any embodiment of this application. The battery module 1000 can provide electrical energy to the electrical device 2000.

[0137] The electrical device 2000 in this application embodiment can be a portable device, an electric toy, a drone, a power tool, an energy storage system, etc. Power tools include metal cutting power tools, cleaning tools, etc., such as electric drills, electric wrenches, vacuum cleaners, robot vacuum cleaners, etc. This application embodiment does not impose any special limitations on the aforementioned electrical device 2000.

[0138] Example Example 1 <Cylindrical Battery Manufacturing> Following the aforementioned method for manufacturing cylindrical batteries, cylindrical battery 1 is manufactured. Cylindrical battery 1 has a radius of 25 mm (R=25) and a height L of 48 mm. The casing 20 is made of nickel-plated carbon steel, and the thickness t1 of the bottom wall 21 of the casing 20 is 0.6 mm.

[0139] Examples 2-1 to 2-4 The manufacturing method is the same as that of the cylindrical battery in Example 1, except that the radius of the cylindrical battery 1 is adjusted, as shown in Table 1.

[0140] Examples 3-1 to 3-4 The manufacturing method is the same as that of the cylindrical battery in Example 1, except that the thickness t1 of the bottom wall 21 is adjusted, as shown in Table 2.

[0141] Examples 4-1 to 4-4 The manufacturing method is the same as that of the cylindrical battery in Example 1, except that the height L of the cylindrical battery 1 is adjusted, as shown in Table 3.

[0142] Comparative Example 1 The manufacturing method is consistent with that of the cylindrical battery in Example 1, except that in Comparative Example 1, the battery is directly bent into the second-shaped flange 225 in step S80, and step S100 is omitted.

[0143] Comparative Example 2 The manufacturing method is the same as that of the cylindrical battery in Example 1, except that the radius of the cylindrical battery 1 is adjusted, as shown in Table 1.

[0144] Measuring H Reference Figure 9 and Figure 10 The cylindrical battery 1 is placed horizontally with its bottom wall 21 facing upwards. Using a device including but not limited to Keyence VR-5000, the outlines of the side wall 22 and bottom wall 21 are scanned from the side of the cylindrical battery 1. A first reference line passing through the outer surface of the side wall body 221 is obtained, and the first reference line is parallel to the central axis C of the cylindrical battery 1. The first reference line is moved horizontally 2mm toward the central axis C to obtain the intersection point of the bottom surface 211 of the bottom wall 21 and the first reference line (this intersection point can be used as a reference point P). A second reference line perpendicular to the first reference line and passing through the intersection point is obtained (since the scanned image is a planar image, the reference plane S is shown as the second reference line in the image). The maximum distance between the bottom surface 211 of the bottom wall 21 and the second reference line in the axial direction Z is measured, which is H mm.

[0145] Table 1 Referring to Examples 1, 2-1 to 2-4, and Comparative Example 1, this embodiment does not seal the interface between the end cap assembly and the housing before cylindrical battery formation, which helps to reduce the bulging deformation of the bottom wall. In this embodiment, H / (R-2) is set to be less than or equal to 0.014, which helps to reduce the risk of poor welding between the bottom wall and the busbar and improve the reliability of the cylindrical battery.

[0146] Referring to Examples 1, 2-1 to 2-4, and Comparative Example 2, in this embodiment, setting R to less than or equal to 60 can reduce the area of ​​the bottom wall, reduce the impact on the bottom wall stiffness, and reduce the bulging deformation of the bottom wall. In this embodiment, setting R to greater than or equal to 15 is beneficial for increasing the capacity of a single cylindrical battery, reducing the number of cylindrical batteries in the battery module, improving energy density, and simplifying the structure of the battery module.

[0147] Table 2 Referring to Table 2, in this embodiment, the thickness t1 of the bottom wall is set to be greater than or equal to 0.2 mm. This is beneficial for increasing the deformation resistance of the bottom wall, reducing bulging deformation, lowering the risk of poor welding between the bottom wall and the busbar, and improving the reliability of the cylindrical battery. In this embodiment, the thickness t1 of the bottom wall is set to be less than or equal to 1 mm. This is beneficial for reducing the space and weight occupied by the bottom wall and increasing the energy density of the cylindrical battery. Optionally, t1 is 0.4 mm to 0.8 mm.

[0148] Table 3 Referring to Table 3, in this embodiment, the axial dimension L of the cylindrical battery is set to be greater than or equal to 20 mm. This is beneficial for increasing the capacity of a single cylindrical battery, reducing the number of cylindrical batteries in the battery module, improving energy density, and simplifying the structure of the battery module. In this embodiment, the axial dimension L of the cylindrical battery is set to be less than or equal to 250 mm. This is beneficial for shortening the venting path during the formation process, reducing the amount of gas remaining in the cylindrical battery, lowering the internal pressure of the cylindrical battery, and reducing the deformation of the bottom wall.

[0149] Although this application has been described with reference to preferred embodiments, various modifications can be made thereto and components can be replaced with equivalents without departing from the scope of this application. In particular, the technical features mentioned in the various embodiments can be combined in any manner, provided there is no structural conflict. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A cylindrical battery, characterized in that, include: The housing includes a bottom wall and an opening, the opening being disposed opposite to the bottom wall along the axial direction of the cylindrical battery; An end cap assembly is insulated from the housing and closes the opening; the end cap assembly and the housing together form a receiving cavity. Electrode assembly is disposed in the receiving cavity; The bottom wall has a bottom surface on the side away from the receiving cavity along the axial direction. The radius of the cylindrical battery is R mm. A reference plane is defined that passes through a reference point on the bottom surface and is perpendicular to the axial direction. The distance between the reference point and the central axis of the cylindrical battery in the radial direction is (R-2) mm. In the axial direction, the distance between the point on the bottom surface that is farthest from the reference plane and the reference plane is H mm, where 0≤H / (R-2)≤0.014 and 15≤R≤60.

2. The cylindrical battery according to claim 1, characterized in that, 0.0008≤H / (R-2)≤0.

007.

3. The cylindrical battery according to claim 1 or 2, characterized in that, 0 < H ≤ 0.8; optionally, 0 < H ≤ 0.

3.

4. The cylindrical battery according to any one of claims 1-3, characterized in that, 25≤R≤45。 5. The cylindrical battery according to any one of claims 1-4, characterized in that, The cylindrical battery has a dimension of 20 mm to 250 mm along the axial direction.

6. The cylindrical battery according to any one of claims 1-5, characterized in that, The shell is made of steel, and the thickness of the bottom wall is 0.2 mm to 1 mm; optionally, the thickness of the bottom wall is 0.4 mm to 0.8 mm.

7. The cylindrical battery according to claim 6, characterized in that, The cylindrical battery satisfies at least one of the following conditions: (1) The tensile strength of the bottom wall is 350 MPa-500 MPa; (2) The Vickers hardness of the bottom wall is 160HV-180HV.

8. The cylindrical battery according to any one of claims 1-7, characterized in that, Neither the end cap assembly nor the housing has an injection port for injecting electrolyte.

9. The cylindrical battery according to any one of claims 1-8, characterized in that, The housing also includes a sidewall, which includes a sidewall body and a transition wall. The sidewall body surrounds the electrode assembly, and the transition wall surrounds the bottom wall and is bent relative to the bottom wall. The transition wall connects the sidewall body and the bottom wall. One end of the sidewall away from the bottom wall defines the opening. The thickness of the bottom wall is greater than the thickness of the sidewall body.

10. The cylindrical battery according to any one of claims 1-9, characterized in that, The housing includes a sidewall connected to the bottom wall and surrounding the electrode assembly; The sidewall has a flange at one end away from the bottom wall, the flange defining the opening, and at least a portion of the flange is located on the side of the end cap assembly away from the electrode assembly in the axial direction; The flange is configured to be shaped by folding the sidewall after the cylindrical battery has been formed.

11. The cylindrical battery according to any one of claims 1-10, characterized in that, The internal pressure of the cavity is 0.1 MPa - 0.17 MPa.

12. A method for manufacturing a cylindrical battery, characterized in that, The method for manufacturing a cylindrical battery according to any one of claims 1-11 includes: A housing is provided, the housing including a sidewall and a bottom wall connected to the sidewall, the sidewall having an opening at one end away from the bottom wall; An electrode assembly is provided, the electrode assembly including a first electrode tab and a second electrode tab with opposite polarities, the first electrode tab and the second electrode tab being located at opposite ends of the electrode assembly; Provide end cap assemblies; The electrode assembly is placed inside the housing, and the sidewall is rolled from the outside to deform the sidewall inward and form a protrusion. The protrusion is located on the side of the electrode assembly away from the bottom wall, and the sidewall includes a sidewall body connected to the protrusion and surrounding the electrode assembly. Connect the first electrode tab to the bottom wall; Connect the second electrode tab to the end cap assembly; Electrolyte is injected into the housing through the opening; The end cap assembly is placed onto the protrusion through the opening, and the end of the sidewall away from the bottom wall is bent to form a flange in a first configuration. The flange constrains the end cap assembly in the axial direction of the cylindrical battery. The bottom wall and the end cap assembly are connected to an external power source for formation. After the transformation is completed, the flange in the first form is bent into a second form to seal the opening. The bending angle of the flange in the second form relative to the side wall body is greater than the bending angle of the flange in the first form relative to the side wall body.

13. A battery module, characterized in that, This includes cylindrical batteries according to any one of claims 1-11 or cylindrical batteries manufactured by the manufacturing method according to claim 12.

14. An electrical appliance, characterized in that, Includes the battery module according to claim 13.

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