Cylindrical lithium ion battery

Abstract

The utility model discloses a cylindrical lithium ion battery. The cylindrical lithium ion battery comprises a hollow battery shell, a pole group is arranged in the battery shell; a positive pole assembly is arranged at the top of the battery shell in a sealing manner; a battery cover plate is arranged at the bottom of the battery shell in a sealing manner; the bottom of the positive pole assembly and the bottom of a rivet in the positive pole assembly are connected with a positive collector plate; the positive collector plate is connected with a positive tab at the top of the pole group; the battery shell is connected with a negative collector plate arranged in the battery shell; the negative electrode confluence plate is connected with a negative electrode lug at the bottom of the electrode group; the cylindrical lithium ion battery disclosed by the utility model is scientific in design, can solve the problem that the yield is low when the existing cylindrical battery is assembled, ensures that the battery has good sealing performance and insulation effect, effectively improves the safety of the battery, reduces the probability of fire and explosion of the battery, and improves the reliability of the battery. And the market application prospect of products of battery manufacturers is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a cylindrical lithium ion battery. Background Art

[0002] At present, cylindrical batteries, especially large cylindrical batteries (i.e. large-sized cylindrical batteries, such as 4680, 4695 and other large cylindrical batteries), have attracted more and more attention from new energy vehicle companies due to their high energy density and high safety. However, there are problems such as low yield rate and low production efficiency in the production process of cylindrical batteries. In addition, there are many problems that affect the safety of lithium-ion batteries in the actual use of cylindrical batteries.

[0003] Among them, for existing cylindrical lithium-ion batteries, due to the large number of components of the positive electrode column assembly, the assembly process is relatively complicated, and the sealing effect of the cylindrical lithium-ion battery and the insulation of the positive and negative electrodes cannot be well guaranteed. The yield rate is low, and there is a risk of electrolyte leakage and short circuit.

[0004] Among them, for the existing cylindrical lithium-ion batteries, considering the structural characteristics of their positive and negative busbars and battery covers, when the battery experiences thermal runaway, the high-pressure gas generated by the lithium-ion battery cannot circulate effectively, causing the cylindrical battery shell to explode horizontally and unable to effectively release pressure, posing many safety risks.

[0005] Therefore, if large cylindrical batteries want to be more widely used and promoted, they must comprehensively consider product characteristics (including electrical performance, safety, manufacturability, etc.), solve the above problems by improving the cylindrical battery structure design and assembly process, and improve the safety of use and manufacturing reliability of cylindrical batteries.

[0006] Therefore, there is an urgent need to develop a technology that can solve the above technical problems. Utility Model Content

[0007] The utility model aims to provide a cylindrical lithium ion battery in view of the technical defects in the prior art.

[0008] To this end, the utility model provides a cylindrical lithium-ion battery, which includes a hollow battery shell;

[0009] A pole group is arranged in the battery housing;

[0010] The top of the battery housing is sealed with a positive electrode column assembly;

[0011] The bottom of the battery housing is sealed with a battery cover;

[0012] The bottom of the rivet in the positive electrode column assembly is connected to the positive electrode busbar, and the positive electrode busbar is connected to the positive electrode ear at the top of the electrode group;

[0013] A battery housing connected to a negative busbar therein;

[0014] The negative electrode busbar is connected to the negative electrode ear at the bottom of the electrode group;

[0015] Among them, the positive pole assembly includes a sealing nail, an outer insulating ring, an inner sealing ring, a rivet and an inner insulating ring;

[0016] The circumferential outer wall of the rivet is respectively covered with an outer insulating ring and an inner sealing ring;

[0017] The outer insulating ring is located above the inner sealing ring and contacts the top surface of the inner sealing ring;

[0018] The outer side of the inner sealing ring is covered with an inner insulating ring;

[0019] A sealing nail is provided at the top center of the rivet;

[0020] The rivet is riveted to the center of the top panel of the battery casing.

[0021] It can be seen from the technical solution provided by the above utility model that, compared with the prior art, the utility model provides a cylindrical lithium-ion battery with a scientific design, which can solve the problem of low yield rate in the assembly of existing cylindrical batteries, ensure that the battery has good sealing and insulation effects, effectively improve battery safety, reduce the probability of battery fire and explosion, and is conducive to improving the market application prospects of battery manufacturers' products, and has great practical significance.

[0022] By applying the cylindrical battery structure design provided by the utility model, the current battery safety concerns can be effectively resolved, and the provided assembly solution has high reliability and is easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a cross-sectional view of a cylindrical lithium-ion battery provided by the utility model;

[0024] Figure 2 This is a structural schematic diagram of a positive electrode column assembly in a cylindrical lithium-ion battery provided by the utility model;

[0025] Figure 3 It is a cross-sectional view of a positive electrode column assembly in a cylindrical lithium-ion battery provided by the utility model;

[0026] Figure 4 This is a structural schematic diagram of a positive busbar in a cylindrical lithium-ion battery provided by the utility model;

[0027] Figure 5 This is a structural schematic diagram of a negative electrode busbar in a cylindrical lithium-ion battery provided by the utility model;

[0028] Figure 6 This is a schematic structural diagram of a negative electrode busbar with a flange structure in a cylindrical lithium-ion battery provided by the utility model;

[0029] Figure 7 This is a structural schematic diagram of a cylindrical lithium-ion battery provided by the utility model, in which a battery cover is placed in an inverted position;

[0030] Figure 8 It is a side cross-sectional view of a negative electrode in which a battery housing, a negative electrode busbar and a battery cover are integrally welded in a cylindrical lithium-ion battery provided by the utility model;

[0031] In the figure, 1-sealing nail;

[0032] 2-Outer insulation ring;

[0033] 201-first boss; 202-insulating ring body; 203-second boss;

[0034] 3-Inner sealing ring;

[0035] 4- Rivets;

[0036] 401-positive pole through hole; 402-first slot; 403-second slot; 404-rivet top surface; 405-rivet side surface; 406-rivet circumferential groove;

[0037] 5-Inner insulation ring;

[0038] 6- positive busbar;

[0039] 601-fuse strip; 602-positive busbar through hole; 603-positive pole connection portion; 604-positive side pole group connection portion; 605-positive busbar hollow groove;

[0040] 7-pole group;

[0041] 8-battery housing;

[0042] 801-first through hole; 802-bottom inner side of the top panel of the battery housing;

[0043] 9-Negative busbar;

[0044] 900-negative busbar through hole; 901-shell connection part; 902-negative side pole group connection part; 903-negative busbar hollow groove; 904-shell connection part outer edge flange;

[0045] 10-battery cover;

[0046] 1001-cover body; 1002-explosion-proof part; 1003-explosion-proof notch; 1004-negative busbar support part; 1005-cover body flange. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0048] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0049] In the description of this patent, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "set" should be understood in a broad sense, for example, it can be fixedly connected or set, or it can be detachably connected or set, or connected or set in one piece. For ordinary technicians in this field, the specific meanings of the above terms in this patent can be understood according to specific circumstances.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0051] See also Figures 1 to 8 , the utility model provides a cylindrical lithium-ion battery, comprising a hollow battery housing 8;

[0052] The battery housing 8 is provided with a pole group 7;

[0053] A positive electrode column assembly is sealed and arranged on the top of the battery housing 8;

[0054] A battery cover 10 is sealed at the bottom of the battery housing 8;

[0055] The bottom of the rivet 4 in the positive electrode column assembly is connected to the positive electrode busbar 6, and the positive electrode busbar 6 is connected to the positive electrode ear at the top of the electrode group 7;

[0056] The battery housing 8 is connected to the negative electrode busbar 9 therein;

[0057] The negative electrode busbar 9 is connected to the negative electrode tab at the bottom of the electrode group 7;

[0058] It should be noted that, in the present invention, the electrode group 7 is placed inside the battery housing 8 , and the upper and lower ends of the battery housing 8 are sealed by the positive electrode column assembly and the battery cover 10 .

[0059] In the present utility model, if Figures 2 to 3 As shown, the positive pole assembly includes a sealing nail 1, an outer insulating ring 2, an inner sealing ring 3, a rivet 4 and an inner insulating ring 5;

[0060] The circumferential outer wall of the rivet 4 is respectively covered with an outer insulating ring 2 and an inner sealing ring 3;

[0061] The outer insulating ring 2 is located above the inner sealing ring 3 and contacts the top surface of the inner sealing ring 3;

[0062] The outer side of the inner sealing ring 3 is covered with an inner insulating ring 5;

[0063] A sealing nail 1 is provided at the top center of the rivet 4;

[0064] The rivet 4 is riveted to the center of the top panel of the battery housing 8 .

[0065] In specific implementation, a first through hole 801 is vertically penetrated at the center of the top panel of the battery housing 8;

[0066] The rivet 4 passes through the first through hole 801;

[0067] A second boss 203 at the lower end of the outer insulating ring 2 is provided between the rivet side surface 405 provided on the outer circumferential side of the middle portion of the rivet 4 and the first through hole 801 of the battery housing 8;

[0068] The inner and outer sides of the second boss 203 at the lower end of the outer insulating ring 2 are in close contact with the rivet side surface 405 and the hole wall of the first through hole 801 respectively.

[0069] It should be noted that the outer insulating ring 2 , the inner sealing ring 3 and the inner insulating ring 5 are fixed by riveting the rivets 4 and the battery case 8 .

[0070] It should also be noted that, for the present invention, after the rivet 4 and the battery housing 8 are riveted, the second boss 203 of the outer insulating ring 2 abuts against the first through hole 801 of the battery housing 8 and the rivet side 405, thereby playing an insulating role.

[0071] In specific implementation, a rivet circumferential groove 406 is provided on the circumferential outer side of the rivet 4;

[0072] The inner side surface of the rivet circumferential groove 406 is the rivet side surface 405;

[0073] The rivet circumferential groove 406 is provided with the insulating ring body 202 in the middle of the outer insulating ring 2, the top panel of the battery housing 8 and the inner sealing ring 3 in order from top to bottom;

[0074] A second through hole is provided at the center of the inner insulating ring 5;

[0075] An inner sealing ring 3 is located in the second through hole;

[0076] The inner and outer sides of the inner sealing ring 3 are in close contact with the rivet side surface 405 and the hole wall of the second through hole respectively.

[0077] Furthermore, it should be noted that a first annular boss 201 is disposed around the top edge of the insulating ring body 202;

[0078] The upper portion of the rivet 4 is located on the inner side of the first boss 201 and is in close contact with the inner side surface of the first boss 201 .

[0079] It should also be noted that the annular second boss 203 is circumferentially disposed on the inner side of the bottom of the insulating ring body 202 , and the inner side surface of the second boss 203 is in close contact with the rivet side surface 405 .

[0080] Further, the bottom surface of the top panel of the battery housing 8 has a bottom inner side surface 802 of the top panel of the battery housing;

[0081] The bottom inner side surface 802 of the top panel of the battery housing is located circumferentially outside the bottom end of the first through hole 801 .

[0082] Further, see Figure 2 , Figure 3 As shown, a receiving cavity for placing the inner sealing ring 3 is formed between the bottom surface of the top panel of the battery housing 8 and the inner groove 406 of the rivet;

[0083] The thickness of the inner sealing ring 3 is greater than the vertical height of its accommodating cavity.

[0084] It should be noted that the thickness of the inner sealing ring 3 is greater than the height of its accommodating cavity. During the riveting process between the rivet 4 and the battery case 8, a large pressure is generated, causing the inner sealing ring 3 to deform. The inner sealing ring 3 is in close contact with the inner side surface 802 of the bottom of the top panel of the battery case and the rivet circumferential groove 406, thereby playing a sealing role and preventing the electrolyte from overflowing from the gap between the battery case 8 and the rivet 4. It should be noted that in the present utility model, the shape of the inner sealing ring 3 is not limited, and its structure can be changed according to the specific design of the positive electrode column assembly.

[0085] It should be noted that see Figure 3 As shown, the inner insulating ring 5 is in close contact with the inner side surface 802 of the bottom of the top panel of the battery case and the inner groove 406 of the rivet during the riveting process of the rivet 4, playing an insulating role to prevent the positive busbar 6 from contacting the inner side surface 802 of the bottom of the top panel of the battery case in the battery case during assembly and use, thereby causing short circuit failure.

[0086] In the present utility model, if Figure 3 As shown, a positive electrode column through hole 401 is provided at the center of the rivet 4;

[0087] In a specific implementation, there is an interference fit between the positive electrode column through hole 401 and the sealing rubber plug.

[0088] It should be noted that the positive electrode through hole 401 is used as an injection hole for electrolyte injection. After the injection is completed, a sealing plug needs to be inserted to preliminarily seal the positive electrode through hole 401. A certain amount of helium is injected while inserting the sealing plug to facilitate the later air tightness test of the cylindrical battery. The aperture of the positive electrode through hole 401 is generally 1.5mm-6mm, and the sealing plug and the positive electrode through hole 401 are assembled in an interference fit.

[0089] In specific implementation, a first slot 402 is provided inside the rivet 4;

[0090] A sealing rubber plug is inserted into the first slot 402;

[0091] It should be noted that the first slot 402 is used to accommodate the sealing plug and serves as the corresponding slot when the positive pole on the positive side (i.e., the rivet 4 serves as the positive pole) penetrates and welds the positive busbar 6. The bottom area of ​​the first slot 402 is used for conductive connection of the positive side of the cylindrical battery, specifically, welding with the positive busbar 6 (specifically, laser penetration welding, and the specific welding position is the positive pole column connection portion in the positive busbar 6).

[0092] In specific implementation, Figure 3 As shown, a second slot 403 is provided inside the rivet 4;

[0093] The second slot 403 is located directly above the first slot 402;

[0094] The positive electrode column through hole 401 is located directly below the first slot 402;

[0095] A sealing pin 1 is disposed in the second slot 403 .

[0096] Furthermore, there is a clearance fit between the second slot 403 and the sealing pin 1 .

[0097] It should be noted that the second slot 403 is used to accommodate the sealing pin 1. To ensure the welding effect of the sealing pin, the material of the sealing pin 1 is generally the same as the material selected for the rivet 4. The thickness of the sealing pin 1 is generally 0.5mm-1.5mm. A clearance fit is adopted between the second slot 403 and the sealing pin 1, and the fitting clearance is 30μm-50μm.

[0098] It should be noted that, for the utility model, the battery shell 8 includes a pole group accommodating cavity, one end (i.e., the bottom end) of which is open for the assembly entrance of the pole group, and the other end (i.e., the top end) is opened to be riveted with the positive pole column assembly, and the rivet 4 in the positive pole column assembly is provided with mutually conductive liquid injection holes (i.e., the positive pole column through hole 401) and a recessed groove (i.e., the second slot 403) suitable for welding the sealing nail 1.

[0099] It should be noted that, in order to ensure the welding effect of the sealing pin, it is generally necessary to perform dry ice cleaning or laser cleaning on the second slot 403 corresponding to the sealing pin 1. To ensure the cleaning effect, the angle between the side and the bottom of the second slot 403 is generally not less than 90 degrees, and the distance from the top of the second slot 403 to the top of the first slot 402 is ≥2mm. This can prevent the sealing pin from having pores, burrs, etc. in the welding process due to the vaporization and climbing of the electrolyte, and can reduce the thermal impact on the sealing plug during the welding process.

[0100] Furthermore, to facilitate the welding of cylindrical battery PACK (assembly), the axial depth of the second groove 403 is smaller than the vertical thickness of the sealing pin 1. Specifically, after the sealing pin 1 is placed, it is about 0.1mm-0.5mm higher than the rivet top surface 404.

[0101] It should be noted that, in the present invention, the rivet 4 is coaxially matched with the battery housing 8 and is arranged at the position of the housing pole through hole (ie, the first through hole 801), and is generally made of aluminum.

[0102] In specific implementation, the outer insulating ring 2, the inner sealing ring 3 and the inner insulating ring 5 are fixed to the upper end of the battery casing by riveting the rivets 4 with the battery casing 8. Among them, the outer insulating ring 2 is generally made of PPS or PFA material to play an insulating role; the inner sealing ring 3 is generally made of fluororubber material to play a sealing role; the inner insulating ring 5 is generally made of PP material to play an insulating role.

[0103] In the present utility model, if Figure 1 and Figure 4 As shown, the diameter of the positive busbar 6 is

[0104] In the present invention, the positive busbar 6 includes a fuse bar 601, a positive busbar through hole 602, a positive column connection portion 603, a positive side electrode group connection portion 604 and a positive busbar hollow groove 605;

[0105] A positive electrode column connection portion 603 is provided at the center of the positive electrode busbar 6;

[0106] A positive busbar through hole 602 is provided at the center of the positive pole connecting portion 603;

[0107] Three positive busbar hollow grooves 605 are arranged around the outer side of the positive electrode column connection portion 603;

[0108] Each hollow groove 605 of the positive busbar is provided with a radially distributed fuse bar 601;

[0109] A positive electrode side electrode group connection portion 604 is provided between any two adjacent positive electrode busbar hollow grooves 605 .

[0110] In a specific implementation, the positive electrode column connecting portion 603 and the bottom of the rivet 4 (i.e., serving as the positive electrode column) are connected by laser welding. The laser welding power is 550w-700w, and the welding trajectory can be a linear swing, a circular swing, etc.

[0111] In a specific implementation, the top surface of the positive electrode column connecting portion 603 is higher than the top surface of the positive electrode side electrode group connecting portion 604 .

[0112] It should be noted that, for the present invention, the positive electrode column connection part 603 can be provided with a protrusion on the positive side pole group connection part 604, the purpose of which is to make the positive electrode column connection part 603 fit more closely with the rivet 4, eliminate the influence of the welding slag of the welding point of the pole group connection part 604 of the positive busbar on the positive electrode column penetration welding, and facilitate laser penetration welding.

[0113] In specific implementation, the three pole group connection parts 604 are arranged in rotational symmetry;

[0114] In specific implementation, the positive electrode side electrode group connection part 604 and the positive electrode ear at the top of the electrode group 7 are laser welded. Specifically, a single-mode continuous laser can be selected, the laser welding power is 600w-700w, the welding trajectory can be in the form of a straight line, a spiral line, a sine curve, etc., the effective welding strength is greater than 45N, and the effective penetration depth is greater than 0.2mm.

[0115] In a specific implementation, the two ends of the fuse bar 601 are respectively connected to the positive electrode column connection part 603 and the positive electrode side electrode group connection part 604, so that the electrical connection on the positive electrode side of the battery can be cut off in time when thermal runaway occurs in the battery.

[0116] It should be noted that between the inner end of the positive electrode side electrode group connection portion 604 and the circumferential outer side of the positive electrode column connection portion 603, as shown in FIG. Figure 4 As shown, there is a reserved gap and the two are not in contact.

[0117] It should be noted that the size of the fuse bar 601 is determined by the short-circuit current of the battery, and its width is generally 0.8mm-3.2mm. It should not affect the conventional fast charging capability of the battery, but should also be able to be blown in time when thermal runaway of the battery occurs. This is a well-known technology and will not be described in detail here.

[0118] It should be noted that, in the present invention, the positive busbar through hole 602 is provided to facilitate the placement of the sealing rubber plug and to facilitate the positioning of the positive busbar 6 and the electrode group 7 during the welding process.

[0119] It should be noted that in the present invention, for cylindrical lithium-ion batteries, after the electrolyte is injected, the presence of the hollow groove 605 of the positive busbar allows the electrolyte to quickly infiltrate, and the gas generated when thermal runaway occurs can flow quickly, thereby achieving the purpose of quickly releasing pressure from the battery cover 10.

[0120] Based on the above structural design, the positive busbar 6 provided by the utility model can cut off the circuit in time when an external short circuit occurs in the battery (it can cut off the electrical connection on the positive electrode side in time when thermal runaway occurs in the battery).

[0121] In the present utility model, if Figure 5 The negative busbar 9 includes a shell connecting portion 901, a negative electrode side electrode group connecting portion 902 and a negative busbar hollow groove 903;

[0122] The negative electrode busbar 9 is provided with three radially distributed negative electrode busbar hollow grooves 903;

[0123] The inner side end of the hollow groove 903 of the negative electrode bus plate converges and intersects with the negative electrode bus plate through hole 900;

[0124] A negative electrode side electrode group connection portion 902 is formed between any two adjacent negative electrode busbar hollow grooves 903;

[0125] The negative electrode group connecting portion 902 is connected to the negative electrode tab at the bottom of the electrode group 7;

[0126] A shell connecting portion 901 is disposed around the outer side of the negative electrode busbar 9;

[0127] The case connecting portion 901 is welded to the battery case 8 .

[0128] In specific implementation, the negative electrode side electrode group connecting portion 902 is connected to the negative electrode ear of the electrode group 7 by laser welding. Specifically, a single-mode continuous laser can be selected, the laser welding power is 700w-800w, the welding trajectory can be in the form of a straight line, a spiral line, a sine curve, etc., the effective welding strength is greater than 60N, and the effective penetration depth is greater than 0.2mm.

[0129] It should be noted that by providing the negative busbar hollow groove 903, the deformation problem of the negative busbar 9 caused by welding stress can be reduced, the electrolyte infiltration can be accelerated, and the blockage problem of the negative busbar 9 on the pressure relief channel can be improved.

[0130] In a specific implementation, the shell connecting portion 901 is welded to the inner wall of the battery shell 8 .

[0131] It should be noted that the shell connection part 901 is lap-welded to the inner wall of the battery shell 8 to achieve electrical connection on the negative electrode side. The welding effect of the side wall lap welding can be promptly judged by appearance. To ensure that the shell connection part 901 and the inner wall of the battery shell 8 are effectively fitted, the angle between the shell connection part 901 and the negative electrode side electrode group connection part 902 is generally 90°-120°.

[0132] In specific implementation, Figure 6 , Figure 7 and Figure 8 As shown, a circle of outer edge flange 904 of the shell connecting portion is arranged around the top edge of the shell connecting portion 901 of the negative busbar 9;

[0133] In a specific implementation, the top and four edges of the battery cover 10 are surrounded by a cover body flange 1005;

[0134] The cover plate body flange 1005 is located on the inner side of the outer edge flange 904 of the shell connection portion and contacts the inner wall of the outer edge flange 904 of the shell connection portion;

[0135] The circumferential outer wall of the outer edge flange 904 of the shell connection portion contacts the circumferential inner wall of the battery shell 8;

[0136] The inner and outer sides of the outer edge flange 904 of the shell connecting portion 901 are welded to the cover plate main body flange 1005 and the circumferential inner wall of the battery shell 8 at the same time.

[0137] Furthermore, the shell connecting portion 901 is integrally welded with the battery shell 8 and the cover plate main body flange 1005 .

[0138] It should be noted that, for the utility model, the shell connection part 901 can be welded integrally with the battery shell 8 and the cover plate main body flange 1005, while in the existing related technology, the negative busbar is generally first penetration welded to the side wall of the battery shell, or the battery cover is penetration welded to the bottom of the negative busbar and then the battery cover is welded and sealed around the battery shell. Since the utility model adopts an integrated welding method, during the process of sealing the shell opening of the battery shell, the utility model can effectively reduce the number of welding times and improve the assembly efficiency of cylindrical batteries by welding the shell connection part 901 integrally with the battery shell 8 and the cover plate main body flange 1005.

[0139] In specific implementation, the shell connection part 901 and the negative electrode side electrode group connection part 902 can be stamped into one piece. Considering that multi-layer sealing welding of dissimilar materials is difficult, the negative electrode busbar 9 can also be designed as a split structure; if a split structure is adopted, the material of the shell connection part 901 is selected to be the same as that of the battery shell 8, and the shell connection part 901 of the negative electrode busbar and the negative electrode side electrode group connection part 902 are pre-welded, and then the negative electrode side electrode group connection part 902 of the negative electrode busbar 9 is welded to the negative electrode ear of the electrode group 7, and then the shell connection part 901 it has is welded to the battery shell 8 and the battery cover plate 10 as a whole.

[0140] In the present utility model, if Figure 7 As shown, the battery cover 10 includes a cover body 1001, an explosion-proof portion 1002, an explosion-proof notch 1003, a negative busbar support portion 1004 and a cover body flange 1005;

[0141] Three negative busbar support parts 1004 are arranged around the top of the cover body 1001;

[0142] The negative busbar support portion 1004 is in contact with the negative side electrode group connection portion 902 in the negative busbar 9;

[0143] A circle of explosion-proof part 1002 is arranged around the cover body 1001;

[0144] The explosion-proof portion 1002 is provided with an arc-shaped explosion-proof notch 1003;

[0145] The top and four edges of the battery cover 10 are surrounded by a cover body flange 1005 .

[0146] It should be noted that the negative busbar support portion 1004 protrudes upward from the cover body 1001 and can be designed into a three-symmetrical spaced ring structure or other shapes. This design can accelerate electrolyte infiltration, form gas flow channels, and improve blockage of pressure relief channels.

[0147] It should be noted that the negative busbar support portion 1004 is in close contact with the negative side electrode group connection portion 902 in the negative busbar 9, ensuring the vibration reliability of the battery during normal use, assisting in improving the mechanical strength of the battery cover 10, reducing the deformation of the cylindrical battery during the assembly process, and accelerating the infiltration of the electrolyte, forming a gas flow channel, and improving the blockage of the pressure relief channel.

[0148] It should be noted that if Figure 7 As shown, the battery cover is provided with an explosion-proof portion 1002, and an explosion-proof notch 1003 is provided on the explosion-proof portion 1002 of the battery cover. The material thickness of the explosion-proof notch 1003 is less than the material thickness of the cover body 1001 of the battery cover 10. When thermal runaway occurs in the battery, the explosion-proof portion opens to quickly release the internal pressure of the battery, thereby effectively improving safety.

[0149] It should also be noted that the explosion-proof notch 1003 is generally stamped, and the shape of the explosion-proof notch can be circular, arc-shaped, crescent-shaped, etc. When the battery has thermal runaway, the explosion-proof notch 1003 in the explosion-proof part 1002 of the battery cover opens, quickly releasing the internal pressure of the battery, effectively improving safety.

[0150] In order to prepare the cylindrical lithium ion battery provided by the utility model, the utility model also provides an assembly method of a cylindrical lithium ion battery, which comprises the following steps:

[0151] Step S1, using laser cutting equipment to cut the pole piece for pole ear preparation;

[0152] In step S1, the angle of the pole lug on the pole piece is 60°-90°, the height of the pole lug is 4.0mm-7.5mm, the width of the pole lug is 3.5mm-5.5mm, and the gap between the pole lugs is 0.01mm-2.00mm;

[0153] Step S2, performing a winding operation of the positive electrode sheet, the negative electrode sheet and the separator, pre-folding the tabs during the winding process, and using a tab flattening device to pre-flatten the tabs, and obtaining a cylindrical battery electrode group after flattening;

[0154] Step S3, performing laser penetration welding operation between the positive electrode busbar 6 and the positive electrode tab of the electrode group 7;

[0155] In step S3, a single-mode continuous laser can be selected, the laser welding power is 600w-700w, the welding trajectory can be in the form of a straight line, a spiral line, a sine curve, etc., the effective welding strength is greater than 45N, and the effective penetration depth is greater than 0.2mm;

[0156] Step S4, encapsulating the positive electrode tab of the electrode group 7 with rubber, and then placing the encapsulated electrode group 7 into a shell (i.e., into the inner cavity of the battery shell 8);

[0157] Step S5, welding the rivet 4 serving as the positive electrode column to the positive electrode busbar 6, that is, performing the operation of penetrating the positive electrode column and welding the positive electrode busbar 6;

[0158] In step S5, a single-mode continuous laser can be selected, the laser welding power can be 550w-700w, the welding trajectory can be linear swing, circular swing, etc., and the effective penetration depth can be 0.1mm-0.4mm;

[0159] Step S6, performing a laser penetration welding operation between the negative electrode busbar 9 and the negative electrode tab of the electrode group 7;

[0160] In step S6, a single-mode continuous laser can be selected, the laser welding power is 700w-800w, the welding trajectory can be in the form of a straight line, a spiral line, a sine curve, etc., the effective welding strength is greater than 60N, and the effective penetration depth is greater than 0.2mm;

[0161] Step S7, performing a lap welding operation between the negative electrode busbar 9 and the inner wall of the battery housing 8;

[0162] In step S7, a ring spot laser can be selected, the laser welding power is 250w-500w, the welding trajectory is a straight line, and the effective welding penetration is 0.1mm-0.3mm;

[0163] Step S8, performing laser sealing welding operation between the battery cover 10 and the battery housing 8;

[0164] In step S8, a ring spot laser can be selected, the laser welding power is 400w-750w, the welding trajectory is a straight line, and the effective welding penetration is 0.15mm-0.3mm;

[0165] Step S9, electrolyte is injected through the positive electrode column through hole 401 in the rivet 4, and then a formation operation is performed. After the formation is completed, the sealing nail 1 is welded in the second slot 403 of the rivet 4, and finally the preparation and manufacturing of the single cylindrical lithium-ion battery is completed.

[0166] In step S9, during the welding operation, a single-mode continuous laser can be selected, the welding trajectory is a straight line, and the effective welding penetration is 0.4mm-0.8mm.

[0167] Compared with the prior art, the utility model provides a cylindrical lithium-ion battery with a scientific design, which can solve the problem of low yield rate in the assembly of existing cylindrical batteries, ensure that the battery has good sealing and insulation effects, effectively improve battery safety, reduce the probability of battery fire and explosion, and is conducive to improving the market application prospects of battery manufacturers' products, and has great practical significance.

[0168] By applying the cylindrical battery structure design provided by the utility model, the current battery safety concerns can be effectively resolved, and the provided assembly solution has high reliability and is easy to industrialize.

[0169] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A cylindrical lithium-ion battery, characterized in that: comprising a hollow battery housing (8); An electrode group (7) is arranged inside the battery housing (8); A positive electrode column assembly is sealed and arranged on the top of the battery housing (8); A battery cover plate (10) is sealed at the bottom of the battery housing (8); The bottom of the rivet (4) in the positive electrode column assembly is connected to the positive electrode busbar (6), and the positive electrode busbar (6) is connected to the positive electrode ear at the top of the electrode group (7); A battery housing (8) connected to a negative electrode busbar (9) contained therein; The negative electrode busbar (9) is connected to the negative electrode tab at the bottom of the electrode group (7); The positive pole assembly comprises a sealing nail (1), an outer insulating ring (2), an inner sealing ring (3), a rivet (4) and an inner insulating ring (5); The circumferential outer wall of the rivet (4) is respectively covered with an outer insulating ring (2) and an inner sealing ring (3); The outer insulating ring (2) is located above the inner sealing ring (3) and is in contact with the top surface of the inner sealing ring (3); The outer side of the inner sealing ring (3) is covered with an inner insulating ring (5); A sealing nail (1) is provided at the top center of the rivet (4); The rivet (4) is riveted to the center of the top panel of the battery housing (8).

2. The cylindrical lithium-ion battery according to claim 1, characterized in that: A first through hole (801) is provided at the center of the top panel of the battery housing (8) and extends vertically therethrough; The rivet (4) passes through the first through hole (801); A second boss (203) at the lower end of the outer insulating ring (2) is provided between a rivet side surface (405) provided on the outer circumferential side of the middle portion of the rivet (4) and the first through hole (801) of the battery housing (8); The inner and outer sides of the second boss (203) at the lower end of the outer insulating ring (2) are in close contact with the rivet side surface (405) and the hole wall of the first through hole (801) respectively.

3. The cylindrical lithium ion battery according to claim 1, characterized in that: A rivet circumferential groove (406) is provided on the circumferential outer side of the rivet (4); The inner side surface of the rivet circumferential groove (406) is the rivet side surface (405); The rivet circumferential groove (406) is provided with an insulating ring body (202) in the middle of the outer insulating ring (2), a top panel of the battery housing (8) and an inner sealing ring (3) in order from top to bottom; A second through hole is provided at the center of the inner insulating ring (5); An inner sealing ring (3), located in the second through hole; The inner and outer sides of the inner sealing ring (3) are in close contact with the rivet side surface (405) and the hole wall of the second through hole respectively.

4. The cylindrical lithium ion battery according to claim 3, characterized in that: The top and surrounding edges of the insulating ring body (202) are surrounded by an annular first boss (201); The upper portion of the rivet (4) is located on the inner side of the first boss (201) and is in close contact with the inner side surface of the first boss (201); The annular second boss (203) is circumferentially arranged on the inner side of the bottom of the insulating ring body (202), and the inner side surface of the second boss (203) is in close contact with the side surface (405) of the rivet.

5. The cylindrical lithium-ion battery according to claim 1, characterized in that: A positive electrode column through hole (401) is provided at the center of the rivet (4); A first groove (402) is provided on the inner side of the rivet (4); A sealing rubber plug is inserted into the first slot (402); a second slot (403) is provided inside the rivet (4); The second slot (403) is located directly above the first slot (402); The positive electrode column through hole (401) is located directly below the first slot (402); A sealing pin (1) is arranged in the second slot (403); There is a clearance fit between the second groove (403) and the sealing pin (1); The axial depth of the second groove (403) is less than the vertical thickness of the sealing pin (1).

6. The cylindrical lithium ion battery according to claim 1, characterized in that: A positive busbar (6), comprising a fuse bar (601), a positive busbar through hole (602), a positive pole column connection portion (603), a positive side electrode group connection portion (604) and a positive busbar hollow groove (605); A positive electrode column connection portion (603) is provided at the center of the positive electrode busbar (6); A positive busbar through hole (602) is provided at the center of the positive pole connecting portion (603); Three positive electrode busbar hollow grooves (605) are arranged around the outer side of the positive electrode column connection portion (603); A radially distributed fuse bar (601) is disposed in each hollow groove (605) of the positive busbar; A positive electrode side electrode group connection portion (604) is provided between any two adjacent positive electrode busbar hollow grooves (605); The positive electrode column connection portion (603) is connected to the bottom of the rivet (4) by laser welding; The top surface of the positive electrode column connection portion (603) is higher than the top surface of the positive electrode side electrode group connection portion (604); The two ends of the fuse bar (601) are respectively connected to the positive electrode column connection part (603) and the positive electrode side electrode group connection part (604).

7. The cylindrical lithium-ion battery according to claim 1, characterized in that: A negative electrode busbar (9), comprising a shell connecting portion (901), a negative electrode side electrode group connecting portion (902) and a negative electrode busbar hollow groove (903); The negative electrode busbar (9) is provided with three radially distributed negative electrode busbar hollow grooves (903); The inner side end of the hollow groove (903) of the negative electrode busbar converges and intersects with the negative electrode busbar through hole (900); A negative electrode side electrode group connection portion (902) is formed between any two adjacent negative electrode busbar hollow grooves (903); A negative electrode side electrode group connecting portion (902) connected to the negative electrode tab at the bottom of the electrode group (7); A shell connecting portion (901) is disposed around the circumferential outer side of the negative electrode busbar (9); The shell connecting portion (901) is welded to the battery shell (8).

8. The cylindrical lithium ion battery according to claim 7, characterized in that: A circle of outer edge flanges (904) of the shell connection portion are arranged around the top and the periphery of the shell connection portion (901) of the negative electrode busbar (9); The top and four edges of the battery cover (10) are surrounded by cover body flanges (1005); The cover plate body flange (1005) is located on the inner side of the outer edge flange (904) of the shell connection portion and contacts the inner wall of the outer edge flange (904) of the shell connection portion; The circumferential outer wall of the outer edge flange (904) of the shell connection portion contacts the circumferential inner wall of the battery shell (8); The inner and outer sides of the outer edge flange (904) of the shell connecting portion (901) are welded to the flange (1005) of the cover plate body and the circumferential inner wall of the battery shell (8) at the same time.

9. The cylindrical lithium-ion battery according to claim 1, characterized in that: A battery cover plate (10), comprising a cover plate body (1001), an explosion-proof portion (1002), an explosion-proof notch (1003), a negative busbar support portion (1004) and a cover plate body flange (1005); Three negative electrode busbar support parts (1004) are arranged around the top of the cover plate body (1001); A negative busbar support portion (1004) in contact with a negative side electrode group connection portion (902) in the negative busbar (9); An explosion-proof portion (1002) is disposed around the cover plate body (1001); The explosion-proof portion (1002) is provided with an arc-shaped explosion-proof notch (1003); The top four edges of the battery cover plate (10) are surrounded by cover plate body flanges (1005).

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