Single battery, preparation method, battery module and battery system

Abstract

The invention discloses a single battery and a preparation method thereof, a battery module and a battery system, and the single battery comprises a hollow battery shell; a roll core is arranged in an inner cavity of the battery shell; a positive pole assembly is arranged at the top opening of the battery shell in a sealing manner; the positive column assembly is connected with a positive lug at the top of the roll core through a positive collector plate; the battery cover plate is hermetically arranged on the inner side of the bottom opening of the battery shell; a negative tab arranged at the bottom of the roll core is connected with the top of the battery cover plate; the structure is scientific in design, the structure of the positive pole assembly serving as the positive pole output end is specially and reasonably designed, the reliability of the mounting structure is guaranteed, a negative pole side confluence disc in a traditional form is omitted, the cylindrical battery assembling procedures are reduced, the material cost is reduced, the yield of the battery is increased, and the structure has great practical significance.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a single cell and a preparation method thereof, a battery module and a battery system. Background Art

[0002] Lithium-ion batteries have the advantages of high specific energy, many cycles and long storage time. They are widely used not only in portable electronic devices (such as mobile phones, digital cameras and laptops), but also in large and medium-sized electric equipment such as electric vehicles, electric bicycles and power tools.

[0003] Single cells, especially cylindrical lithium-ion batteries, generally include battery casings, winding cores, insulating sealing plastic parts and various metal parts used for electrical connections. Since they are composed of many structural parts, the assembly process is relatively complicated. During their mass production, it is impossible to effectively reduce their manufacturing costs and improve the assembly yield of lithium-ion batteries.

[0004] Therefore, if cylindrical batteries, especially large cylindrical lithium-ion batteries (i.e. large-sized cylindrical batteries, such as 4680, 4695 and other large cylindrical batteries), want to be more widely used and promoted, they must continue to comprehensively consider product characteristics (including electrical performance and safety performance, manufacturability, process reliability, etc.).

[0005] However, the existing cylindrical lithium-ion batteries have many assembly processes, which are repeated and redundant; the structural design of the positive output terminal is unreasonable, and the installation structure is not reliable enough; the negative terminal welding connection method has low reliability, and the battery cover structure is not reasonably designed.

[0006] Therefore, there is an urgent need to develop a technology that can solve the above technical problems. Summary of the invention

[0007] The purpose of the present invention is to provide a single cell and a preparation method, a battery module and a battery system in view of the technical defects in the prior art.

[0008] To this end, the present invention provides a single battery, which includes a hollow battery casing;

[0009] The inner cavity of the battery housing is provided with a winding core;

[0010] A positive electrode column assembly is sealed at the top opening of the battery housing, and the top of the positive electrode column assembly is exposed on the top surface of the battery housing;

[0011] The positive electrode column assembly is connected to the positive electrode ear at the top of the winding core through the positive electrode busbar;

[0012] A battery cover is sealedly disposed on the inner side of the bottom opening of the battery housing;

[0013] The negative electrode ear at the bottom of the coil is connected to the top of the battery cover;

[0014] A positive pole assembly, including a rivet, an outer insulating ring, a rivet sealing ring, and an inner insulating ring;

[0015] The upper and lower ends of the rivet are provided with a rivet upper platform and a rivet lower platform respectively;

[0016] The middle circumferential outer wall of the rivet is circumferentially provided with a rivet circumferential groove;

[0017] A rivet circumferential groove located between the upper platform and the rivet lower platform;

[0018] The upper and lower ends of the circumferential outer side of the rivet circumferential groove are respectively covered with an outer insulating ring and a circular rivet sealing ring;

[0019] The bottom surface of the outer insulating ring is in tight contact with the top surface of the rivet sealing ring;

[0020] An inner insulating ring is sleeved on the circumferential outer side of the rivet sealing ring;

[0021] A rivet, riveted to the center of the top of the battery casing;

[0022] A positive busbar, comprising a positive busbar body, a positive pole connecting portion, a busbar hollow groove and a positive pole side winding core connecting portion;

[0023] A positive pole column connection portion is provided at the center of the positive busbar body so as to protrude upward;

[0024] A plurality of radially distributed busbar hollow grooves are arranged on the positive busbar body;

[0025] The radial inner end of the hollow groove of the busbar is connected to the edges around the connecting portion of the positive electrode column;

[0026] The remaining area of ​​the positive electrode busbar body except the busbar hollow groove and the positive electrode column connection part is the positive electrode side winding core connection part.

[0027] In addition, the present invention also provides a battery module, which includes a plurality of single cells as described above.

[0028] In addition, the present invention also provides a battery system, which includes at least one battery module as described above.

[0029] In addition, the present invention also provides a method for preparing the above-mentioned single cell battery, which comprises the following steps:

[0030] Step S1, preparing positive electrode sheets and negative electrode sheets;

[0031] 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 flatten the tabs, and obtaining a cylindrical battery winding core after flattening;

[0032] Step S3, performing a laser penetration welding operation between the positive electrode busbar on the positive electrode side and the positive electrode ear of the winding core;

[0033] Step S4, encapsulating the positive electrode ear of the core roll with glue;

[0034] Step S5, performing a laser penetration welding operation between the battery cover and the negative electrode ear of the winding core;

[0035] Step S6, putting the welded coil core into the shell, and welding the rivet serving as the positive electrode column to the positive electrode busbar;

[0036] Step S7, performing a laser sealing welding operation between the battery cover plate and the bottom opening of the battery housing;

[0037] Step S8, injecting electrolyte into the battery shell through the center hole of the battery cover, and then performing battery formation. After the formation is completed, inserting the sealing plug, and then welding the sealing pins in the center groove of the battery cover, finally completing the preparation of the cylindrical single battery.

[0038] It can be seen from the technical solution provided by the present invention that, compared with the prior art, the present invention provides a single cell and a preparation method, a battery module and a battery system, which are scientifically designed, and the structure of the positive electrode column assembly as the positive electrode output terminal is specially and reasonably designed, thereby ensuring the reliability of the installation structure and the sealing effect of the battery, thereby ensuring the production quality of the battery, improving the yield rate of the battery, and having great practical significance.

[0039] The present invention eliminates the traditional negative busbar and changes the negative electrode electrical connection to a form in which the battery cover directly penetrates the negative electrode tab, thereby reducing the cost of battery cell materials, reducing assembly steps, and improving assembly yield.

[0040] By applying the present invention, the present invention effectively improves the use safety and manufacturing reliability of cylindrical batteries by improving the structural design and assembly process of single cylindrical batteries.

[0041] The application of the present invention is conducive to solving the problem of low yield rate of existing cylindrical batteries during assembly, effectively reducing production costs, ensuring battery safety, and improving the market application prospects of battery manufacturers' products.

[0042] By applying the single cylindrical battery structure design provided by the present invention, the problems of high production cost and low yield rate in the current mass production of cylindrical batteries can be effectively solved. The provided structural design and assembly scheme are highly reliable and easy to industrialize. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a cross-sectional view of a single cell provided by the present invention;

[0044] Figure 2 It is a structural schematic diagram of a positive electrode column assembly in a single cell provided by the present invention;

[0045] Figure 3 It is a cross-sectional view of the installation state of a positive electrode column assembly in a single cell provided by the present invention;

[0046] Figure 4 It is a structural schematic diagram of a busbar in a single cell provided by the present invention;

[0047] Figure 5a It is a structural schematic diagram of a single cell (specifically a cylindrical lithium-ion battery) provided by the present invention, in which a battery cover is placed upright;

[0048] Figure 5b It is a structural schematic diagram of a single cell (specifically a cylindrical lithium-ion battery) provided by the present invention, in which a battery cover is placed in an inverted position;

[0049] Figure 6 It is a side cross-sectional view of the negative electrode of a single battery provided by the present invention after the battery housing, winding core, battery cover and other components are assembled;

[0050] In the figure, 1-rivet;

[0051] 1001- rivet upper platform; 1002- rivet lower platform;

[0052] 101-positive pole slot; 102-rivet top surface; 103-rivet side surface; 104-rivet circumferential groove;

[0053] 2-outer insulating ring; 201-first boss; 202-insulating ring body; 203-second boss;

[0054] 3- rivet sealing ring; 4- inner insulating ring; 5- positive busbar;

[0055] 501-positive pole connection part; 502-bus plate hollow groove; 503-positive side winding core connection part

[0056] 6-winding core; 7-battery housing;

[0057] 701-first through hole; 702-inner side of the top panel;

[0058] 8-battery cover;

[0059] 801-cover plate body; 802-explosion-proof part; 803-explosion-proof notch; 804-negative electrode side winding core connection part; 805-cover plate body flange; 806-cover plate center boss; 807-cover plate center slot; 808-cover plate center hole.

[0060] 9- Sealing rubber plug; 10- Sealing nail. DETAILED DESCRIPTION

[0061] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] 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.

[0063] 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.

[0064] 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 invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0065] See also Figures 1 to 4 , Figure 5a to Figure 5b , Figure 6, the present invention provides a single battery, comprising a hollow battery housing 7;

[0066] The inner cavity of the battery housing 7 is provided with a winding core 6;

[0067] A positive electrode column assembly is sealed at the top opening of the battery housing 7, and the top of the positive electrode column assembly is exposed on the top surface of the battery housing 7;

[0068] The positive electrode column assembly is connected to the positive electrode ear at the top of the winding core 6 through the positive electrode busbar 5;

[0069] A battery cover plate 8 is sealedly disposed inside the bottom opening of the battery housing 7;

[0070] The negative electrode ear at the bottom of the winding core 6 is connected to the top of the battery cover 8 .

[0071] It should be noted that, in the present invention, the upper and lower openings of the battery housing 7 can be sealed by the positive electrode column assembly and the battery cover 8 , thereby ensuring the sealing effect of the battery housing 7 .

[0072] In the present invention, see Figure 2 , Figure 3 , a positive electrode column assembly, comprising a rivet 1, an outer insulating ring 2, a rivet sealing ring 3, and an inner insulating ring 4;

[0073] The upper and lower ends of the rivet 1 respectively have a rivet upper platform 1001 and a rivet lower platform 1002;

[0074] The central circumferential outer wall of the rivet 1 is circumferentially provided with a rivet circumferential groove 104;

[0075] The rivet circumferential groove 104 is located between the upper platform 1001 and the rivet lower platform 1002;

[0076] The upper and lower ends of the circumferential outer side of the rivet circumferential groove 104 are respectively covered with an outer insulating ring 2 and a circular rivet sealing ring 3;

[0077] The bottom surface of the outer insulating ring 2 is in tight contact with the top surface of the rivet sealing ring 3.

[0078] The circumferential outer side of the rivet sealing ring 3 is covered with an inner insulating ring 4;

[0079] The rivet 1 is riveted to the center position of the top of the battery housing 7 .

[0080] In specific implementation, a circular first through hole 701 is vertically provided at the top center of the battery housing 7;

[0081] The first through hole 701 is the top opening of the battery housing 7;

[0082] The rivet 1 passes through the first through hole 701 .

[0083] In specific implementation, the outer insulating ring 2 includes an insulating ring body 202;

[0084] A first boss 201 protruding upward is disposed around the outer edge of the top of the insulating ring body 202;

[0085] A second boss 203 protruding downward is disposed around the bottom inner edge of the insulating ring body 202;

[0086] The second boss 203 is located between the rivet side surface 103 of the rivet circumferential groove 104 of the rivet 1 and the surrounding hole wall of the first through hole 701;

[0087] Furthermore, the inner and outer sides of the second boss 203 are respectively tightly fitted with the rivet side surface 103 on the circumferential outer side of the rivet circumferential groove 104 of the rivet 1 and the surrounding hole walls of the first through hole 701 .

[0088] In specific implementation, the top of the rivet 1 is provided with a horizontally distributed rivet top surface 102;

[0089] A concave positive electrode column slot 101 is provided at the top center of the rivet 1;

[0090] The bottom area of ​​the positive electrode column slot 101 is used to be connected to the positive electrode busbar 5 located below by laser penetration welding.

[0091] Furthermore, the radial cross-section of the positive electrode slot 101 is an isosceles trapezoid.

[0092] It should be noted that the positive electrode column slot 101 serves as the corresponding slot when the positive electrode column on the positive electrode side (i.e., the rivet 1 serves as the positive electrode column) penetrates and welds the positive electrode busbar 5. The bottom area of ​​the positive electrode column slot 101 is used for conductive connection on the positive electrode side of the cylindrical battery. Specifically, the bottom area of ​​the positive electrode column slot 101 is used for welding with the positive electrode busbar 5 located below. The specific connection method adopted is: laser penetration welding, and the specific welding position is the positive electrode column connection portion 501 in the positive electrode busbar 5.

[0093] In specific implementation, the bottom of the rivet 1 is connected to the top of the positive busbar 5;

[0094] The bottom of the positive electrode busbar 5 is connected to the positive electrode tab at the top of the winding core 6 .

[0095] It should be noted that the outer insulating ring 2 , the rivet sealing ring 3 and the inner insulating ring 4 are fixed by riveting the rivet 1 and the battery case 7 .

[0096] It should also be noted that, for the present invention, after the rivet 1 and the battery housing 7 are riveted, the inner and outer sides of the second boss 203 of the outer insulating ring 2 are respectively abutted against (i.e., tightly contacted with) the first through hole 701 of the battery housing 7 and the rivet side 103, thereby playing an insulating role.

[0097] In specific implementation, the rivet circumferential groove 104 is provided with the insulating ring body 202 in the middle of the outer insulating ring 2, the second boss 203, the inner edge of the top panel of the battery housing 7 and the rivet sealing ring 3;

[0098] The insulating ring body 202 and the rivet sealing ring 3 are respectively located at the upper and lower sides of the second boss 203 .

[0099] In specific implementation, a second through hole is provided at the center of the inner insulating ring 4;

[0100] The rivet sealing ring 3 is located in the second through hole;

[0101] The inner and outer sides of the rivet sealing ring 3 are in close contact with the rivet side surface 103 of the rivet 1 and the surrounding hole walls of the second through hole, respectively.

[0102] In a specific implementation, the rivet upper platform 1001 is located on the inner side of the first boss 201 of the outer insulating ring 2 and is in tight contact with the inner side wall of the first boss 201 .

[0103] In specific implementation, the rivet sealing ring 3 is located between the bottom surface of the top panel of the battery housing 7 and the top surface of the rivet lower platform 1002, and its upper and lower sides are respectively in tight contact with the bottom surface of the top panel of the battery housing 7 and the top surface of the rivet lower platform 1002;

[0104] In a specific implementation, the bottom surface of the top panel of the battery housing 7 has a top panel inner side surface 702;

[0105] The inner side surface 702 of the top panel is located outside the bottom end of the first through hole 701 in the circumferential direction;

[0106] The rivet sealing ring 3 is in tight contact with the inner side surface 702 of the top panel.

[0107] Furthermore, a gap for placing the rivet sealing ring 3 is provided between the inner side surface 702 of the top panel and the top surface of the rivet lower platform 1002;

[0108] The vertical thickness of the gap is smaller than the vertical thickness of the elastic rivet sealing ring 3 when it is not compressed by external force.

[0109] It should be noted that, for the present invention, the vertical thickness of the gap is smaller than the vertical thickness of the elastic rivet sealing ring 3 when not compressed by external force. Then, the larger pressure generated during the riveting process between the rivet 1 and the battery housing 7 can cause the rivet sealing ring 3 to deform, thereby causing the rivet sealing ring 3 to be in tight contact with the inner side surface 702 of the top panel, the top surface of the rivet lower platform 1002 and the rivet circumferential groove 104, thereby ensuring the sealing effect and playing a good sealing role. Therefore, by applying the present invention, it is possible to effectively prevent the electrolyte from overflowing from the gap between the battery housing 7 and the rivet 1.

[0110] In specific implementation, there is no specific restriction on the shape of the rivet sealing ring 3, and its structure can be modified according to the specific design of the positive electrode column assembly.

[0111] In specific implementation, the inner insulating ring 4 includes a circular inner insulating ring body 401;

[0112] The bottom of the inner insulating ring body 401 is surrounded by an inner insulating ring limiting boss 402 protruding downward;

[0113] The inner portion of the inner insulating ring body 401 is located between the inner side surface 702 of the top panel and the top surface of the lower platform 1002 of the rivet;

[0114] The upper and lower sides of the inner part of the inner insulating ring body 401 are in close contact with the inner side surface 702 of the top panel and the top surface of the rivet lower platform 1002 respectively;

[0115] Furthermore, the inner side wall of the inner insulating ring limiting boss 402 is in tight contact with the circumferential outer wall of the rivet lower platform 1002 .

[0116] Furthermore, the vertical thickness of the gap between the inner side surface 702 of the top panel and the top surface of the rivet lower platform 1002 is smaller than the vertical thickness of the elastic inner insulating ring body 401 when not compressed by external force.

[0117] It should be noted that, for the present invention, see Figure 3 As shown, the inner insulating ring 4 is in close contact with the inner side surface 702 of the top panel and the rivet circumferential groove 104 during the riveting process of the rivet 1, and plays an insulating role to prevent the positive busbar 5 from causing short circuit failure due to contact with the bottom inner side surface 702 of the top panel of the battery casing during assembly and use.

[0118] In the present invention, a winding core accommodating cavity is provided inside the battery housing 7;

[0119] The lower end opening of the winding core accommodating cavity is used as an assembly entrance of the winding core.

[0120] In a specific implementation, the rivet 1 is coaxially matched with the battery housing 7, and is generally made of aluminum.

[0121] In specific implementation, the outer insulating ring 2, the rivet sealing ring 3 and the inner insulating ring 4 are fixed to the upper end of the battery casing by riveting the rivet 1 with the battery casing 7. Among them, the outer insulating ring 2 is generally made of PPS or PFA material to play an insulating role; the rivet sealing ring 3 is generally made of fluororubber material to play a sealing role; the inner insulating ring 4 is generally made of PP material to play an insulating role.

[0122] In the present invention, see Figure 1 , Figure 4 As shown, the positive busbar 5 includes a positive busbar body 500, a positive pole column connection portion 501, a busbar hollow groove 502 and a positive side winding core connection portion 503;

[0123] A positive electrode column connecting portion 501 is provided at the center of the positive electrode busbar body 500 so as to protrude upward;

[0124] The positive electrode busbar body 500 is provided with a plurality of (for example, three) radially distributed busbar hollow grooves 502;

[0125] The included angles between any two adjacent busbar hollow slots 502 are equal;

[0126] The radial inner end of the hollow groove 502 of the busbar is connected to the edges of the positive electrode column connecting portion 501 .

[0127] The remaining area of ​​the positive electrode busbar body 500 except the busbar hollow groove 502 and the positive electrode column connecting portion 501 is the positive electrode side winding core connecting portion 503 .

[0128] In a specific implementation, the radial inner end of the hollow groove 502 of the busbar extends into the positive electrode column connecting portion 501 , and the extending length is less than half of the radius of the positive electrode column connecting portion 501 .

[0129] In specific implementation, three notches 504 are provided around the edges of the positive busbar body 500;

[0130] It should be noted that the three notches 504 have the following functions: to provide positioning during the loading process of the positive busbar;

[0131] In a specific implementation, the cross-sectional shape of the positive electrode column connecting portion 501 is circular.

[0132] In specific implementation, the diameter of the positive busbar 5 is φ38.0 mm-φ45.0 mm;

[0133] In a specific implementation, the positive electrode column connecting portion 501 is connected to the bottom of the rivet 1 (i.e., serving as the positive electrode column) by laser welding. The laser welding power is 400w-700w, and the welding trajectory can be linear swing, circular swing, etc.

[0134] In a specific implementation, the top surface of the positive electrode column connection portion 501 is higher than the top surface of the positive electrode side winding core connection portion 503 .

[0135] It should be noted that, for the present invention, the positive electrode column connection part 501 protrudes upward from the positive electrode side winding core connection part 503, the purpose of which is to make the positive electrode column connection part 501 fit more closely with the rivet 1, eliminate the influence of the welding spot welding slag at the positive electrode side winding core connection part 503 of the positive busbar on the positive electrode column penetration welding, and facilitate laser penetration welding.

[0136] It should be noted that after the positive electrode column 501 is connected to the rivet 1 by laser welding, in order to prevent poor welding at the welding position of the positive electrode column 501 and affect the sealing of the single battery, a sealing treatment can be performed on the positive electrode column slot 101, including applying sealant, welding sealing nails, etc.

[0137] In specific implementation, three busbar hollow grooves 502 are provided on the positive busbar body 500;

[0138] The three hollow grooves 502 of the busbar are arranged in rotational symmetry;

[0139] In specific implementation, the positive electrode side core connection part 503 and the positive electrode ear at the top of the core 6 are connected by laser welding. Specifically, a single-mode continuous laser can be selected, and the laser welding power is 300w-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 20N, and the effective melting depth is greater than 0.2mm.

[0140] It should be noted that in the present invention, for cylindrical single-cell lithium-ion batteries, after the electrolyte is injected, the presence of the hollow groove 502 of the positive busbar allows the electrolyte to quickly infiltrate the winding core, and when thermal runaway occurs, the gas generated inside the battery can circulate quickly, which is beneficial to ensuring the safety of the battery.

[0141] In the present invention, see Figure 5a , Figure 5b The battery cover 8 includes a cover body 801, an explosion-proof portion 802, an explosion-proof notch 803, a negative electrode side winding core connection portion 804, a cover body flange 805, a cover center boss 806, a cover center slot 807 and a cover center hole 808;

[0142] The cover plate body 801 is provided with a negative electrode side winding core connecting portion 804 protruding upward (i.e., concave upward);

[0143] The negative electrode side winding core connection portion 804 is connected to the negative electrode ear at the bottom of the winding core 6 (specifically, it is laser welded to the electrode ear on the negative electrode side of the winding core);

[0144] The bottom of the cover body 801 is surrounded by an explosion-proof portion 802;

[0145] The explosion-proof portion 802 is provided with an explosion-proof notch 803;

[0146] The bottom edges of the battery cover 8 are surrounded by a cover body flange 805;

[0147] A cover plate center boss 806 protruding downward is provided at the center of the negative electrode side winding core connection portion 804;

[0148] Inside the cover plate center boss 806, a concave cover plate center slot 807 is provided;

[0149] In specific implementation, the negative side winding core connection part 804 is connected to the negative pole ear of the winding core 6 by laser welding. Specifically, a single-mode continuous laser can be selected, and the laser welding power is 300w-550w. 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 30N, and the effective melting depth is greater than 0.15mm.

[0150] It should be noted that, for the present invention, the negative side core connection portion 804 of the battery cover and the negative pole ear of the core 6 are directly connected to the negative pole by laser welding, while in the existing related technology, the negative busbar is generally used for transfer, that is, a negative busbar is first welded to the negative pole ear of the core, and then the negative busbar is connected to the battery case or the battery cover by laser welding. Since the present invention directly adopts the form of connecting the battery cover and the negative pole ear of the core, it can effectively reduce the cost of the battery cell, reduce the assembly process, and improve the assembly efficiency of the single cylindrical battery.

[0151] In specific implementation, a sealing nail 10 is provided in the center slot 807 of the cover plate;

[0152] In a specific implementation, a cover plate center hole 808 is vertically provided at the center position of the cover plate center slot 807;

[0153] A sealing rubber plug 9 is inserted upwardly through the center hole 808 of the cover plate.

[0154] It should be noted that the shape and size of the sealing pin 10 correspond to the shape and size of the cover plate center slot 807 into which the sealing rubber plug 9 is inserted. The cover plate center hole 808 is used for liquid injection and placement of the sealing rubber plug 10.

[0155] Furthermore, the overall cross-sectional shape of the sealing pin 10 is circular.

[0156] In specific implementation, the cover plate body flange 805 is connected and sealed with the bottom opening of the battery housing 7 by laser welding. Specifically, a ring spot laser can be selected, the laser welding power is 450w-800w, the welding trajectory is a straight line, and the effective welding penetration is 0.15mm-0.30mm.

[0157] In specific implementation, for the single cell provided by the present invention, after the liquid injection and exhaust are completed, the sealing plug 9 is inserted into the center hole 808 of the cover plate, and then the center groove 807 of the cover plate and the sealing pin 10 are connected and sealed by laser welding. Specifically, a single-mode continuous laser can be selected, and the laser welding power is 300w-500w. The welding trajectory can be a linear swing, a circular swing, etc.

[0158] In a specific implementation, the top surface of the negative electrode side winding core connecting portion 804 is in close contact with the negative electrode ear at the bottom of the winding core 6 .

[0159] For specific implementation, see Figure 5b As shown, the shape of the negative electrode side winding core connection portion 804 specifically includes a central connection portion 8041 and four auxiliary connection portions 8042;

[0160] The shape of the central connecting portion 8041 is annular;

[0161] The cover plate center boss 806 is located inside the center connection portion 8041;

[0162] Four auxiliary connection parts 8042 are evenly distributed on the outer side of the central connection part 8041 in the circumferential direction;

[0163] Further, the four auxiliary connection parts 8042 are distributed in rotational symmetry with the center point of the cover plate center boss 806 as the center;

[0164] It should be noted that the negative electrode side winding core connection portion 804 protrudes upward from the cover plate body 801, and is in close contact with the negative electrode ear at the bottom of the winding core 6 after assembly to ensure the vibration reliability of the battery during normal use. The negative electrode side winding core connection portion 804 can be designed as follows: Figure 5b The shape shown in the figure can accelerate the electrolyte infiltration, form a gas flow channel, and improve the blockage of the pressure relief channel.

[0165] In a specific implementation, the material thickness of the explosion-proof notch 803 is smaller than the material thickness of the cover plate body 801 of the battery cover plate 8 .

[0166] It should be noted that if Figure 5bAs shown, an explosion-proof portion 802 is provided on the battery cover, and an explosion-proof notch 803 is provided on the explosion-proof portion 802 of the battery cover. The material thickness of the explosion-proof notch 803 is less than the material thickness of the cover body 801 of the battery cover 8. When thermal runaway occurs in the battery, the explosion-proof portion opens, which can quickly release the internal pressure of the battery and effectively improve safety.

[0167] It should be noted that the explosion-proof notch 803 is generally formed by stamping, and the shape of the explosion-proof notch can be circular, arc-shaped or crescent-shaped. When the battery has thermal runaway, the explosion-proof notch 803 in the explosion-proof part 802 of the battery cover opens, quickly releasing the internal pressure of the battery, effectively improving the safety of the battery.

[0168] It should be noted that the center groove 807 of the cover plate is used to accommodate the sealing nail 10. To ensure the welding effect of the sealing nail 10, the material of the sealing nail 10 is generally the same as the material selected for the cover plate 8, and the thickness of the sealing nail 10 is generally 0.01mm-0.6mm.

[0169] In a specific implementation, the angle between the side walls and the top surface of the central slot 807 of the cover plate is greater than or equal to 90°.

[0170] 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 center groove 807 of the cover plate corresponding to the sealing pin 10 after liquid injection. To ensure the cleaning effect, the angle between the side wall and the top surface of the center groove 807 of the cover plate is generally not less than 90 degrees.

[0171] In order to prepare a single cell provided by the present invention, the present invention also provides a method for preparing a single cell (specifically a single cylindrical lithium ion battery), comprising the following steps:

[0172] Step S1, using laser cutting equipment (existing equipment) to prepare positive and negative electrode sheets with tabs cut;

[0173] It should be noted that the full-pole ear technology is proposed in contrast to the traditional single-pole ear or multi-pole ear. The current full-pole ear technology for lithium-ion batteries mainly includes two types, namely, flattened pole ear forming and cut and stacked pole ear forming. The cut and stacked pole ear forming technology is widely used because of its low self-discharge rate and less metal foreign matter. In order to ensure the flattening effect of the cut pole ear, the pole ears on the edges of the positive and negative electrode sheets need to be cut with laser die-cutting equipment. The pole ears after cutting are cut pole ears.

[0174] It should be noted that the preparation technology of the positive and negative electrode sheets with cut tabs is the existing well-known preparation technology of full-tab batteries, which will not be described in detail here.

[0175] In step S1, the angle of the tabs on the positive and negative electrode sheets is 60°-90°, the height of the tabs is 3.0 mm-7.5 mm, the width of the tabs is 2.5 mm-5.5 mm, and the gap between the tabs is 0.01 mm-2.00 mm.

[0176] Step S2, winding the positive electrode sheet, the negative electrode sheet and the separator, pre-folding the tabs during the winding process, and flattening the tabs using a tab flattening device (the tab flattening operation is an existing conventional tab processing operation, and is performed using an existing tab flattening device), and a cylindrical battery winding core is obtained after flattening;

[0177] Step S3, performing a laser penetration welding operation between the positive electrode busbar 5 on the positive electrode side and the positive electrode ear of the winding core 6;

[0178] In step S3, a single-mode continuous laser can be selected, the laser welding power can be 300w-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 20N, and the effective penetration depth is greater than 0.2mm;

[0179] Step S4, encapsulating the positive electrode ear of the winding core 6 with glue;

[0180] Step S5, performing a laser penetration welding operation between the battery cover plate 8 and the negative electrode ear of the winding core 6;

[0181] In step S5, a single-mode continuous laser can be selected, the laser welding power is 300w-550w, 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 40N, and the effective penetration depth is greater than 0.15mm;

[0182] Step S6, putting the welded coil core into the shell, and welding the rivet 1 as the positive electrode column to the positive electrode busbar 5;

[0183] In step S6, a single-mode continuous laser can be selected, the laser welding power can be 400w-700w, the welding trajectory can be linear swing, circular swing, etc., and the effective penetration depth can be 0.1mm-0.4mm;

[0184] Step S7, performing a laser sealing welding operation between the battery cover plate 8 and the bottom opening of the battery housing 7;

[0185] In step S7, 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;

[0186] Step S8, injecting electrolyte into the battery housing 7 through the center hole 808 in the battery cover 8, and then performing battery formation. After the formation is completed, inserting the sealing plug 9, and then welding the sealing pin 10 in the center groove 807 of the battery cover 8, finally completing the preparation of the cylindrical single battery.

[0187] In step S8, during the welding operation, a single-mode continuous laser can be selected, the laser welding power is 300w-500w, and the welding trajectory can be a linear swing, a circular swing, etc.

[0188] Based on the single cell provided by the present invention, the present invention further provides a battery module, which includes a plurality of the single cells mentioned above.

[0189] In a specific implementation, when the battery module includes a plurality of single cells, the plurality of single cells are connected in parallel, in series, or in series-parallel (ie, a combination of series and parallel).

[0190] It should be noted that, for a battery module, specific methods of connecting multiple single cells in series, in parallel, and in series and parallel are conventional known technologies and will not be described in detail herein.

[0191] Based on the battery module provided by the present invention, the present invention further provides a battery system, which includes at least one battery module as described above.

[0192] In a specific implementation, when the battery system includes a plurality of battery modules, the plurality of battery modules are connected in parallel, in series, or in series and in parallel.

[0193] It should be noted that, for a battery system, specific methods of connecting multiple battery modules in series, in parallel, and in series and parallel are conventional known technologies and will not be described in detail herein.

[0194] 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 scope of protection of the present invention.

Claims

1. A single cell battery, It is characterized in that comprising a hollow battery housing (7); The inner cavity of the battery housing (7) is provided with a winding core (6); A positive electrode column assembly is sealed at the top opening of the battery housing (7), and the top of the positive electrode column assembly is exposed on the top surface of the battery housing (7); The positive electrode column assembly is connected to the positive electrode ear at the top of the winding core (6) through the positive electrode busbar (5); A battery cover plate (8) is sealedly disposed on the inner side of the bottom opening of the battery housing (7); The negative electrode ear at the bottom of the winding core (6) is connected to the top of the battery cover (8); A positive pole assembly, comprising a rivet (1), an outer insulating ring (2), a rivet sealing ring (3), and an inner insulating ring (4); The upper and lower ends of the rivet (1) are respectively provided with a rivet upper platform (1001) and a rivet lower platform (1002); A rivet circumferential groove (104) is circumferentially arranged on the middle circumferential outer wall of the rivet (1); A rivet circumferential groove (104) located between the upper platform (1001) and the rivet lower platform (1002); The upper and lower ends of the circumferential outer side of the rivet circumferential groove (104) are respectively covered with an outer insulating ring (2) and a circular rivet sealing ring (3); The bottom surface of the outer insulating ring (2) is in tight contact with the top surface of the rivet sealing ring (3); An inner insulating ring (4) is sleeved on the circumferential outer side of the rivet sealing ring (3); A rivet (1) is riveted to the center of the top of the battery housing (7); A positive electrode busbar (5), comprising a positive electrode busbar body (500), a positive electrode column connection portion (501), a busbar hollow groove (502) and a positive electrode side winding core connection portion (503); A positive electrode column connecting portion (501) is provided at the center of the positive electrode busbar body (500) so as to protrude upwards; A plurality of radially distributed collector plate hollow grooves (502) are provided on the positive collector plate body (500); The radial inner end of the hollow groove (502) of the busbar is connected to the edges around the positive electrode column connecting portion (501); The remaining area of ​​the positive electrode busbar body (500) except the busbar hollow groove (502) and the positive electrode column connection part (501) is the positive electrode side winding core connection part (503).

2. The single cell according to claim 1, It is characterized in that The outer insulating ring (2) comprises an insulating ring body (202); A first boss (201) protruding upward is disposed around the outer edges of the top of the insulating ring body (202); A second boss (203) protruding downward is disposed around the inner edge of the bottom of the insulating ring body (202); The second boss (203) is located between the rivet side surface (103) of the circumferential side wall of the rivet circumferential groove (104) of the rivet (1) and the surrounding hole wall of the first through hole (701); The inner and outer sides of the second boss (203) are respectively tightly fitted with the rivet side surface (103) provided on the circumferential outer side of the rivet circumferential groove (104) of the rivet (1) and the surrounding hole walls of the first through hole (701); and / or, An inner insulating ring (4), comprising a circular inner insulating ring body (401); The bottom of the inner insulating ring body (401) is surrounded by an inner insulating ring limiting boss (402) protruding downward; The inner portion of the inner insulating ring body (401) is located between the inner side surface (702) of the top panel and the top surface of the lower platform (1002) of the rivet; The upper and lower sides of the inner part of the inner insulating ring body (401) are in tight contact with the inner side surface (702) of the top panel and the top surface of the lower platform (1002) of the rivet respectively; The inner side wall of the inner insulating ring limiting boss (402) is in tight contact with the circumferential outer wall of the rivet lower platform (1002); The vertical thickness of the gap between the inner side surface (702) of the top panel and the top surface of the lower platform (1002) of the rivet is smaller than the vertical thickness of the inner insulating ring body (401) when not compressed by external force.

3. The single cell according to claim 1, It is characterized in that A circular first through hole (701) is vertically provided at the top center of the battery housing (7); The first through hole (701) is the top opening of the battery housing (7); The rivet (1) passes through the first through hole (701); The top of the rivet (1) is provided with a horizontally distributed rivet top surface (102); A concave positive electrode column slot (101) is provided at the top center of the rivet (1); The bottom area of ​​the positive electrode column slot (101) is used to be connected to the positive electrode busbar (5) located below by laser penetration welding.

4. The single cell according to claim 2, It is characterized in that The rivet circumferential groove (104) is provided with an insulating ring body (202) in the middle of the outer insulating ring (2), a second boss (203), an inner edge of the top panel of the battery housing (7) and a rivet sealing ring (3); The insulating ring body (202) and the rivet sealing ring (3) are respectively located on the upper and lower sides of the second boss (203); A second through hole is provided at the center of the inner insulating ring (4); A rivet sealing ring (3), located in the second through hole; The inner and outer sides of the rivet sealing ring (3) are in close contact with the rivet side surface (103) of the rivet (1) and the surrounding hole walls of the second through hole respectively; and / or, The rivet upper platform (1001) is located on the inner side of the first boss (201) of the outer insulating ring (2) and is in tight contact with the inner side wall of the first boss (201); and / or, The rivet sealing ring (3) is located between the bottom surface of the top panel of the battery housing (7) and the top surface of the rivet lower platform (1002), and its upper and lower sides are respectively in tight contact with the bottom surface of the top panel of the battery housing (7) and the top surface of the rivet lower platform (1002); and / or, The bottom surface of the top panel of the battery housing (7) has an inner side surface (702) of the top panel; The inner side surface (702) of the top panel is located outside the bottom circumference of the first through hole (701); The rivet sealing ring (3) is in tight contact with the inner side surface (702) of the top panel; A gap for placing a rivet sealing ring (3) is provided between the inner side surface (702) of the top panel and the top surface of the rivet lower platform (1002); The vertical thickness of the gap is smaller than the vertical thickness of the rivet sealing ring (3) when it is not compressed by external force.

5. The single cell according to claim 1, It is characterized in that The radial inner end of the hollow groove (502) of the busbar extends into the positive electrode column connecting portion (501), and the extending length is less than half of the radius of the positive electrode column connecting portion (501); and / or, The top surface of the positive electrode column connection portion (501) is higher than the top surface of the positive electrode side winding core connection portion (503); and / or, The positive electrode busbar body (500) is provided with three busbar hollow grooves (502); The three hollow grooves (502) of the busbar are arranged in rotational symmetry; and / or, Three notches (504) are arranged on the edges of the positive electrode busbar body (500).

6. The single cell according to claim 1, It is characterized in that A battery cover (8), comprising a cover body (801), an explosion-proof portion (802), an explosion-proof notch (803), a negative electrode side winding core connection portion (804), a cover body flange (805), a cover center boss (806), a cover center slot (807) and a cover center hole (808); The cover plate body (801) is provided with a negative electrode side winding core connecting portion (804) protruding upward; A negative electrode side winding core connection portion (804) connected to the negative electrode ear at the bottom of the winding core (6); The bottom of the cover body (801) is surrounded by an explosion-proof portion (802); The explosion-proof portion (802) is provided with an explosion-proof notch (803); The bottom edges of the battery cover (8) are surrounded by cover body flanges (805); A cover plate center boss (806) protruding downward is provided at the center of the negative electrode side winding core connection portion (804); An upwardly concave cover plate center slot (807) is provided inside the cover plate center boss (806).

7. The single cell according to claim 6, It is characterized in that A sealing nail (10) is arranged in the central groove (807) of the cover plate; A cover plate center hole (808) is vertically provided at the center position of the cover plate center slot (807); A sealing rubber plug (9) is inserted upwardly through the center hole (808) of the cover plate; and / or, The top surface of the negative electrode side winding core connection portion (804) is in close contact with the negative electrode ear at the bottom of the winding core (6); and / or, The shape of the negative electrode side winding core connection part (804) specifically includes a central connection part (8041) and four auxiliary connection parts (8042); The central connecting portion (8041) is in the shape of a ring; The cover plate central boss (806) is located inside the central connecting portion (8041); Four auxiliary connection parts (8042) are evenly distributed on the outer side of the central connection part (8041) in the circumferential direction; and / or, The material thickness of the explosion-proof notch (803) is less than the material thickness of the cover plate body (801) of the battery cover plate (8); and / or, The included angle between the side walls around the central slot (807) of the cover plate and the top surface is greater than or equal to 90°.

8. A battery module, It is characterized in that The invention comprises a plurality of single cells according to any one of claims 1 to 7.

9. A battery system, It is characterized in that Comprising at least one battery module as claimed in claim 8.

10. A method for preparing a single cell according to any one of claims 1 to 7, It is characterized in that The following steps are involved: Step S1, preparing positive electrode sheets and negative electrode sheets; 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 flatten the tabs, and obtaining a cylindrical battery winding core after flattening; Step S3, performing a laser penetration welding operation between the positive electrode busbar (5) on the positive electrode side and the positive electrode ear of the winding core (6); Step S4, encapsulating the positive electrode ear of the winding core (6) with glue; Step S5, performing a laser penetration welding operation between the battery cover plate (8) and the negative electrode ear of the winding core (6); Step S6, placing the welded coil core into a shell, and welding the rivet (1) serving as the positive electrode column to the positive electrode busbar (5); Step S7, performing a laser sealing welding operation between the battery cover plate (8) and the bottom opening of the battery housing (7); Step S8, injecting electrolyte into the battery housing (7) through the cover plate center hole (808) in the battery cover plate (8), and then performing battery formation operation. After the formation is completed, inserting the sealing plug (9), and then welding the sealing pin (10) in the cover plate center groove (807) of the battery cover plate (8), finally completing the preparation of the cylindrical single battery.

Images