Battery and connection method

Abstract

Disclosed in the present application are a battery and a connection method. The battery comprises a jelly roll and a case, wherein a plurality of negative tabs are provided with a gap at one end of the jelly roll, and are respectively bent and overlap with each other so as to form a complete tab structure at one end of the jelly roll; and the jelly roll is placed in the case, the case comprises a bottom plate, and the negative tabs are electrically connected to the bottom plate.

Description

Battery and connection method

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 25, 2023, with application number 202311798381.8. The entire contents of the above application are incorporated by reference into this application.

[0002] Technical Field

[0003] The present application relates to the field of battery technology, for example, to batteries and connection methods.

[0004] Background Art

[0005] In a full-pole-ear cylindrical battery, the negative electrode of the core is welded to the busbar through the negative electrode ear, and then the busbar is welded to the steel shell, making the steel shell the negative electrode.

[0006] Technical issues

[0007] A busbar is used as a welding bridge between the negative electrode ear and the steel shell. The two welding processes not only increase the welding cost, but also increase the internal resistance, thereby reducing the flow area of ​​the full-electrode cylindrical battery and failing to meet the needs of high-current charging and discharging. The presence of the busbar will limit the width of the material area on the positive and negative electrode sheets, resulting in a reduction in the active material content on the positive and negative electrode sheets, and failing to increase the capacity of the full-electrode cylindrical battery.

[0008] Technical Solutions

[0009] This application proposes a battery and a connection method that can increase the battery's flow area, meet large current charging and discharging requirements, and improve the battery's capacity.

[0010] A battery comprises: a winding core, wherein a plurality of negative electrode tabs are provided in a gap at one end of the winding core, wherein the plurality of negative electrode tabs are bent and overlapped with each other; and a shell, wherein the winding core is placed in the shell, wherein the shell comprises a bottom plate, and the negative electrode tabs are electrically connected to the bottom plate.

[0011] A connection method, applied to the battery, is used to electrically connect the negative electrode ear of the battery's winding core to the bottom plate of the battery's shell. The connection method includes: bending and arranging multiple negative electrode ears respectively and overlapping each other; electrically connecting the negative electrode ears to the bottom plate to form a negative electrode in the shell; wherein, during the electrical connection process, the sum of the thickness A1 of the positive electrode sheet, the thickness of the diaphragm, and the thickness of the negative electrode sheet in the winding core and the height A2 of the negative electrode ear meet a first preset connection condition, the width A3 of the negative electrode ear and the height A2 of the negative electrode ear meet a second preset connection condition, and the gap L1 between two adjacent negative electrode ears meets a third preset connection condition.

[0012] Beneficial effects

[0013] The beneficial effects of the present application are as follows: by arranging multiple negative tabs in the gap at one end of the winding core, the multiple negative tabs are bent and arranged respectively and overlapped with each other to form a complete tab structure on the negative end surface of the winding core; then the winding core is placed in a shell, and the negative tab is directly electrically connected to the bottom plate of the shell, so that the shell becomes the negative electrode; by directly electrically connecting the negative tab to the shell, the electrical connection of the busbar is eliminated, and the number of electrical connections is reduced to one. Compared with the two electrical connection processes used in the related art, the electrical connection cost is reduced, and the electrical connection area between the negative tab and the bottom plate can be increased, and the internal resistance of the single electrical connection and the internal resistance of the busbar are reduced, so that the internal resistance of the entire battery is smaller, thereby increasing the flow area of ​​the battery to meet the requirements of high current charging and discharging; at the same time, since the busbar is omitted in the shell, the usable space between the negative tab and the bottom plate is increased, thereby increasing the width of the material area on the positive and negative electrode sheets, thereby increasing the active material content on the positive and negative electrode sheets, and thus improving the capacity of the battery.

[0014] The connection method of the present application is used to electrically connect the negative electrode ear in the battery directly to the bottom plate of the shell, with fewer electrical connections and lower electrical connection costs; and, during the electrical connection process, the following three connection conditions need to be met, that is, the sum of the thickness of the positive electrode sheet, the thickness of the diaphragm and the thickness of the negative electrode sheet A1 and the height A2 of the negative electrode ear meet the first preset connection condition, the width A3 of the negative electrode ear and the height A2 of the negative electrode ear meet the second preset connection condition, and the gap L1 between two adjacent negative electrode ears meets the third preset connection condition, so as to ensure the electrical connectivity between the negative electrode ear and the bottom plate, and prevent the occurrence of electrical connection failure, thereby ensuring that the negative electrode ear can be smoothly electrically connected to the bottom plate.

[0015] BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG1 is a schematic structural diagram of a battery provided in an embodiment of the present application;

[0017] FIG2 is a schematic structural diagram of a negative electrode sheet after winding provided in an embodiment of the present application;

[0018] FIG3 is a schematic diagram of the unfolded structure of a negative electrode sheet before winding provided in an embodiment of the present application;

[0019] FIG4 is a schematic structural diagram of a winding core provided in an embodiment of the present application;

[0020] FIG5 is a schematic structural diagram of a side surface of a bottom plate provided in an embodiment of the present application;

[0021] FIG6 is a schematic structural diagram of the bottom surface of a base plate provided in an embodiment of the present application;

[0022] FIG7 is a flow chart of a connection method provided in an embodiment of the present application.

[0023] Description of reference numerals:

[0024] 1-winding core; 11-negative electrode ear; 12-negative electrode sheet; 13-positive electrode sheet; 14-upper separator; 15-lower separator;

[0025] 2-shell; 21-base plate.

[0026] Implementation Methods of the Application

[0027] All features disclosed in this specification, or all steps in the disclosed methods or processes, except mutually exclusive features and / or steps, can be combined in any manner.

[0028] Any feature disclosed in this specification, unless otherwise stated, may be replaced by an equivalent or similar alternative feature. That is, unless otherwise stated, each feature is merely an example of a set of equivalent or similar features. Throughout this specification, like reference numerals refer to like elements.

[0029] The technical solution of this application is explained below with reference to the accompanying drawings and through specific implementation methods.

[0030] Example 1

[0031] This embodiment provides a battery with a large flow area to meet high-current charging and discharging requirements and increase battery capacity. The battery is a steel-cased cylindrical battery. In other embodiments, the battery can be a prismatic battery or other irregularly shaped battery; the battery shape is not limited herein.

[0032] As shown in Figures 1 to 3, the battery includes a winding core 1 and a shell 2; wherein, a plurality of negative electrode tabs 11 are provided in a gap at one end of the winding core 1. The plurality of negative electrode tabs 11 are arranged in a spiral structure on the negative end surface of the winding core 1, and the plurality of negative electrode tabs 11 are bent and adhered to the negative end surface of the winding core 1; in two adjacent arc-shaped circles of the spiral structure, the plurality of negative electrode tabs 11 overlap each other so that the plurality of negative electrode tabs 11 are electrically connected to each other, thereby forming a complete tab structure on the negative end surface of the winding core 1, which can improve the battery power and facilitate the subsequent electrical connection between the negative electrode tabs 11 and the shell 2; the winding core 1 is placed in the shell 2, and the shell 2 includes a bottom plate 21, and the negative electrode tabs 11 are electrically connected to the bottom plate 21. In this embodiment, the shell 2 is a cylindrical steel shell, and the electrical connection direction between the negative electrode tab 11 and the bottom plate 21 is shown by arrow A in Figure 1.

[0033] In this embodiment, the negative electrode tab 11 is electrically connected to the bottom plate 21 by welding. In other embodiments, riveting, screw connection, or conductive colloid connection can also be used to achieve the electrical connection between the negative electrode tab 11 and the bottom plate 21, and the electrical connection method is not limited.

[0034] Compared with the related art, the battery in this embodiment omits the busbar; by directly welding the negative electrode ear 11 to the bottom plate 21 of the shell 2, the shell 2 becomes the negative electrode. Since the busbar welding is omitted, the number of welding times is reduced to one, which reduces the welding cost compared to the two welding processes used in the related art. It can also increase the welding area between the negative electrode ear 11 and the bottom plate 21, and reduce the internal resistance of one welding and the internal resistance of the busbar, so that the internal resistance of the entire battery is small, thereby increasing the flow area of ​​the battery to meet the requirements of large current charging and discharging; at the same time, since the busbar is omitted in the shell 2, the usable space between the negative electrode ear 11 and the bottom plate 21 is increased, thereby increasing the width of the material area on the positive electrode sheet 13 and the negative electrode sheet 12, thereby increasing the active material content on the positive electrode sheet 13 and the negative electrode sheet 12, and thus increasing the capacity of the battery. Among them, the capacity of the battery is one of the important performance indicators for measuring battery performance. It represents the amount of electricity discharged by the battery under certain conditions such as discharge rate, temperature, and termination voltage.

[0035] Since the battery in this embodiment only needs one welding to weld the negative electrode ear 11 to the shell 2, compared with the related art of first welding the negative electrode ear of the winding core to the busbar and then welding the busbar to the shell twice, the welding yield between the negative electrode ear 11 and the shell 2 is higher, thereby ensuring the welding effect between the negative electrode ear 11 and the shell 2.

[0036] In this embodiment, the width of the material area on the positive electrode sheet 13 and the negative electrode sheet 12 is increased, so that the active material content on the positive electrode sheet 13 and the negative electrode sheet 12 can be increased, thereby increasing the capacity of the battery by 0.2%-0.6%; and, because the busbar is removed, the internal resistance of a single weld can be reduced by 3%-10%, and the internal resistance of the busbar can also be reduced by 0.1%-0.9%; that is, the capacity and internal resistance of the battery in this embodiment are improved, making the battery more economical. Among them, the width of the material area on the positive electrode sheet 13 and the negative electrode sheet 12 refers to the size of the material area on the positive electrode sheet 13 and the negative electrode sheet 12 where the active material is provided, in the axial direction of the shell 2.

[0037] As shown in Figures 3 and 4 , the winding core 1 includes a positive electrode sheet 13, separators (upper separator 14 and lower separator 15), and a negative electrode sheet 12, which are wound together. A negative electrode tab 11 is located at one end of the negative electrode sheet 12. The sum of the thicknesses of the positive electrode sheet 13, the separators (upper separator 14 and lower separator 15), and the negative electrode sheet 12 is A1. The height of the negative electrode tab 11 is A2. 0.05±0.01<A1 / A2<0.1±0.01 to ensure weldability between the negative electrode tab 11 and the base plate 21. The winding process of the positive electrode sheet 13, separators (upper separator 14 and lower separator 15), and negative electrode sheet 12 to form the winding core 1 is a common process in the related art and will not be described in detail here. In this embodiment, 0.05<A1 / A2<0.1.

[0038] As shown in Figure 3, the width of the negative electrode tab 11 is A3, and 0.4±0.05<A3 / A2<0.9±0.05, thereby ensuring weldability between the negative electrode tab 11 and the bottom plate 21. In this embodiment, 0.4<A3 / A4<0.9.

[0039] As shown in FIG3 , the gap between two adjacent negative electrode tabs 11 is L1, and L1 is less than 0.2±0.05 mm, thereby ensuring the weldability between the negative electrode tab 11 and the bottom plate 21. In this embodiment, L1 is less than 0.2 mm.

[0040] By setting the parameters of the positive electrode sheet 13, diaphragm (upper diaphragm 14 and lower diaphragm 15), negative electrode sheet 12 and negative electrode ear 11 in the winding core 1, that is, 0.05±0.01<A1 / A2<0.1±0.01, 0.4±0.05<A3 / A4<0.9±0.05, L1<0.2±0.05 mm; when the winding core 1 meets the parameter settings at the same time, the weldability between the negative electrode ear 11 on the winding core 1 and the bottom plate 21 of the shell 2 can be guaranteed, so that the negative electrode ear 11 can be welded to the bottom plate 21.

[0041] The negative electrode ear 11 is welded to the bottom plate 21 by laser deep penetration welding. The laser deep penetration welding method can, on the one hand, make the welding depth of the welding area between the negative electrode ear 11 and the bottom plate 21 deeper, thereby ensuring the welding stability between the negative electrode ear 11 and the bottom plate 21; on the other hand, it can make the welding area occupied by the welding area smaller, so that there is still enough welding space on the bottom plate 21 of the shell 2 to ensure the welding of other components on the bottom plate 21.

[0042] As shown in Figures 5 and 6, the welding area between the negative electrode tab 11 and the bottom plate 21 is set as a spiral line that matches the spiral structure. The spiral line can ensure that most of the negative electrode tabs 11 can be welded to the bottom plate 21, ensuring the welding stability between the bottom plate 21 and multiple negative electrode tabs 11.

[0043] The weld depth of the weld area is H1, and the thickness of the bottom plate 21 is H2. 0.2±0.05

[0044] The distance from the starting point of the spiral line to the center of the winding core 1 is H3, the radius of the bottom plate 21 is r1, H3>r1×0.2; and the distance from the end point of the spiral line to the center of the winding core 1 is H4, H4<r1×0.85; so that the spiral line can ensure that most of the negative electrode ears 11 are welded to the bottom plate 21, ensuring the stability of the welding between the bottom plate 21 and multiple negative electrode ears 11.

[0045] The length of the spiral is L2, the radius of the winding core 1 is r2, L2>r2×15.71, so that the length of the spiral should not be too short, thereby ensuring that most of the negative electrode ears 11 can be welded to the bottom plate 21; at the same time, it can avoid the high internal resistance and high welding cost caused by the spiral being too long.

[0046] The pitch of the helix is ​​L3, 0.1±0.01 mm<L3<0.5±0.01 mm. This allows the helix pitch to be more appropriate when the length of the helix is ​​constant, thereby ensuring uniform welding between the bottom plate 21 and the multiple negative electrode tabs 11, ensuring that the bottom plate 21 can be uniformly welded to most of the negative electrode tabs 11, and avoiding welding that is too close or too sparse. The pitch of the helix refers to the distance between two adjacent turns of the helix. In this embodiment, 0.1 mm<L3<0.5 mm.

[0047] ​The battery in this embodiment omits the busbar and directly welds the negative electrode tab 11 to the bottom plate 21 of the shell 2, so as to increase the capacity and flow area of ​​the battery, so that the battery can meet the requirements of large current charging and discharging; and, by setting the parameters of the positive electrode sheet 13, the diaphragm (upper diaphragm 14 and lower diaphragm 15), the negative electrode sheet 12 and the negative electrode tab 11 in the winding core 1, the weldability between the electrode tab on the winding core 1 and the bottom plate 21 can be ensured; and, by setting the welding method, welding depth, welding area and spiral line welding parameters, the welding stability between the negative electrode tab 11 and the bottom plate 21 can be ensured, and the separation between the negative electrode tab 11 and the bottom plate 21 can be avoided.

[0048] That is, for the battery in this embodiment, the winding core 1 needs to meet the following three conditions at the same time: 0.05±0.01<A1 / A2<0.1±0.01, 0.4±0.05<A3 / A4<0.9±0.05, L1<0.2±0.05 mm, so as to ensure the weldability between the negative electrode ear 11 of the formed winding core 1 and the bottom plate 21 of the shell 2; and the welding parameters need to meet any one or more of the following six conditions: laser deep penetration welding, 0.2±0.05r1×0.2 and H4<r1×0.85, L2>r2×15.71, 0.1±0.01 mm<L3<0.5±0.01 mm, the welding stability between the negative electrode ear 11 and the bottom plate 21 can be ensured, and the separation between the negative electrode ear 11 and the bottom plate 21 can be avoided, thereby ensuring the performance of the entire battery.<h1>

[0049] Example 2

[0050] This embodiment proposes a connection method based on the battery in Example 1. The connection method is used to weld the negative electrode ear 11 of the battery to the bottom plate 21 of the housing 2. As shown in FIG7 , the connection method includes the following steps:

[0051] S1: Bend and adhere the multiple negative electrode tabs 11 arranged in a spiral structure to the negative end surface of the winding core 1, and in the spiral structure, the negative electrode tabs 11 of two adjacent circles overlap each other to form a complete tab structure on the negative end surface of the winding core 1.

[0052] S2: Weld the negative electrode tab 11 to the bottom plate 21 to form the housing 2 into a negative electrode.

[0053] During the welding process, the sum A1 of the thickness of the positive electrode sheet 13, the thickness of the diaphragm (upper diaphragm 14 and lower diaphragm 15) and the thickness of the negative electrode sheet 12 and the height A2 of the negative electrode tab 11 meet the first preset connection condition, the width A3 of the negative electrode tab 11 and the height A2 of the negative electrode tab 11 meet the second preset connection condition, and the gap L1 between two adjacent negative electrode tabs 11 meets the third preset connection condition, thereby ensuring the weldability between the negative electrode tab 11 and the bottom plate 21.

[0054] The first preset connection condition is 0.05±0.01<A1 / A2<0.1±0.01 in Example 1; the second preset connection condition is 0.4±0.05<A3 / A4<0.9±0.05 in Example 1; the third preset connection condition is L1<0.2±0.05 mm in Example 1, so that a winding core 1 that meets the connection conditions can be formed, and the negative electrode ear 11 on the winding core 1 can be directly welded to the bottom plate 21.

[0055] The connection method in this embodiment can directly weld the negative electrode tab 11 to the bottom plate 21 of the shell 2 through a single welding process, with fewer welding times and lower welding costs. Moreover, since only one welding is involved, a high welding yield between the negative electrode tab 11 and the bottom plate 21 can be ensured. At the same time, through the setting of the first preset connection condition, the second preset connection condition and the second preset connection condition, the weldability between the negative electrode tab 11 on the winding core 1 and the bottom plate 21 can be ensured.

Claims

1. A battery, comprising: A wound core (1), at one end of the wound core (1), a plurality of negative tabs (11) are provided with gaps, and the plurality of negative tabs (11) are respectively bent and overlapped with each other; A housing (2), the wound core (1) is placed inside the housing (2), the housing (2) includes a bottom plate (21), and the negative tabs (11) are electrically connected to the bottom plate (21).

2. The battery according to claim 1, wherein, The wound core (1) includes a positive electrode plate (13), separators (14, 15) and a negative electrode plate (12) that are wound around each other. The negative tabs (11) are provided at one end of the negative electrode plate (12). The sum of the thickness of the positive electrode plate (13), the thickness of the separators (14, 15) and the thickness of the negative electrode plate (12) is A1, and the height of the negative tab (11) is A2, 0.05 ± 0.01 < A1 / A2 < 0.1 ± 0.

01.

3. The battery according to claim 2, wherein, The width of the negative tab (11) is A3, 0.4 ± 0.05 < A3 / A2 < 0.9 ± 0.

05.

4. The battery according to any one of claims 1-3, wherein, The gap between two adjacent negative tabs (11) is L1, L1 < 0.2 ± 0.05 mm.

5. The battery according to any one of claims 1-4, wherein, The negative tab (11) is electrically connected to the bottom plate (21) by laser deep penetration welding.

6. The battery according to any one of claims 1-5, wherein, The electrical connection area between the negative tab (11) and the bottom plate (21) is set as a spiral. The electrical connection depth of the electrical connection area is H1, and the thickness of the bottom plate (21) is H2, 0.2 ± 0.05 < H1 / H2 < 0.6 ± 0.

05.

7. The battery according to claim 6, wherein, The distance from the starting point of the spiral to the center of the wound core (1) is H3, and the radius of the bottom plate (21) is r1, H3 > r1 × 0.2; the distance from the ending point of the spiral to the center of the wound core (1) is H4, H4 < r1 × 0.

85.

8. The battery according to claim 6 or 7, wherein, The length of the spiral is L2, and the radius of the wound core (1) is r2, L2 > r2 × 15.

71.

9. The battery according to any one of claims 6-8, wherein, The pitch of the spiral is L3, 0.1 ± 0.01 mm < L3 < 0.5 ± 0.01 mm.

10. A connection method, applied to the battery according to any one of claims 1-9, the connection method is used to electrically connect the negative tabs of the wound core of the battery to the bottom plate of the housing of the battery, and the connection method includes: Bending and overlapping a plurality of negative tabs respectively; Electrically connecting the negative tabs to the bottom plate so that the housing forms a negative electrode; Wherein, during the electrical connection process, the sum A1 of the thickness of the positive electrode plate, the thickness of the separator and the thickness of the negative electrode plate in the wound core and the height A2 of the negative tab satisfy a first preset connection condition, the width A3 of the negative tab and the height A2 of the negative tab satisfy a second preset connection condition, and the gap L1 between two adjacent negative tabs satisfies a third preset connection condition.

Images