Battery and preparation method thereof

Abstract

The battery comprises a pole piece, a pole lug and a diaphragm, wherein the pole piece is provided with an empty foil part, the tab is arranged on the side surface of the empty foil part through the embedding part, and the tab is connected with a shell of the battery through the connecting part; the tab provided by the invention is connected to the pole piece through the embedding part after being prepared and formed by another process instead of being formed by directly cutting on the pole piece, so that the procedure of forming the tab by die cutting on the pole piece is directly saved; the connecting part is directly connected with the shell, so that the arrangement of a confluence plate is omitted, metal chips are prevented from being formed in die cutting and confluence plate welding procedures, and the reject ratio of voltage drop of the battery is further reduced; moreover, the length L2 of the embedded part is larger than the length L1 of the connecting part, so that the connecting area of the embedded part and the empty foil part of the pole piece is increased, the resistance of the connection between the tabs and the pole pieces is reduced, and the current throughput between the pole pieces and the tabs is improved; the embodiment of the invention also provides a preparation method of the battery, which has the above beneficial effects.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and more specifically, to a battery and a method for preparing the same. Background Art

[0002] In the related art, a hollow foil portion is provided on the pole piece of the battery, and the hollow foil portion is die-cut to form a pole ear. When forming the winding core, the die-cut pole ear is flattened or patted, and then welded through a busbar to form a full-pole ear battery. However, in the preparation process of the full-pole ear battery, the two processes of die-cutting and busbar welding are very likely to form metal chips, resulting in poor voltage drop of the battery. In addition, the die-cutting equipment and busbar welding equipment are complex and expensive, which increases the cost. At the same time, the pole ear die-cutting process and busbar welding process are inefficient, which seriously affects the production efficiency. In addition, the connection between the pole ear and the pole piece will result in poor connection, large connection resistance and insufficient current flow. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a battery that saves the steps of die cutting and busbar welding, reduces the defective rate of battery voltage drop, reduces the resistance of the connection between the pole piece and the pole ear, and increases the current flow between the pole piece and the pole ear.

[0004] In a first aspect, an embodiment of the present application provides a battery, comprising:

[0005] A pole piece, wherein the pole piece is provided with a hollow foil portion extending along a first direction;

[0006] A diaphragm, wherein the diaphragm and the pole piece are stacked and wound into a winding core; and

[0007] The pole ear comprises an embedded portion and a connecting portion, wherein at least a portion of the embedded portion is sandwiched between the pole piece and the diaphragm adjacently arranged in the winding core and connected to the side of the hollow foil portion of the pole piece, the connecting portion is connected to the embedded portion and extends outside the winding core, and the connecting portion is used to be connected to the housing;

[0008] The length of the embedded portion along the first direction is L2, and the length of the connecting portion along the first direction is L1, wherein L2>L1.

[0009] In one embodiment, L2=A·2πr, wherein r is the radius of the embedded portion around the axis of the winding core, A is the proportional coefficient, and the value range of A is [0.25, 0.33].

[0010] In one embodiment, the embedded portion is disposed on the inner side of the pole piece close to the axis of the winding core; or,

[0011] The embedded portion is arranged on the outer side surface of the pole piece away from the axis of the winding core.

[0012] In one embodiment, the pole lug has a first embedded portion and a second embedded portion, and the first embedded portion and the second embedded portion are respectively arranged on an inner side surface close to the axis of the winding core and an outer side surface away from the axis of the winding core of the same pole piece.

[0013] In one embodiment, the pole piece further comprises an active material portion extending along the first direction, the active material portion and the hollow foil portion are arranged along a second direction, and the second direction intersects with the first direction;

[0014] There are multiple pole ears, each of which includes the embedded part and the connecting part connected to each other, the multiple embedded parts extend along the first direction and are arranged in the hollow foil part along the first direction, and the multiple connecting parts extend to the side of the hollow foil part away from the active material part.

[0015] In one embodiment, a plurality of grooves are formed on the hollow foil portion, the embedded portions are correspondingly disposed in the grooves, and the thickness of the embedded portions is equal to the depth of the grooves.

[0016] In one embodiment, the connecting portion includes a first sub-portion and a second sub-portion, the second sub-portion is connected between the first sub-portion and the embedded portion, the thickness of the embedded portion is less than the thickness of the first sub-portion, and the thickness of the second sub-portion gradually increases along the connection direction of the embedded portion, the second sub-portion and the first sub-portion.

[0017] In one embodiment, the battery further comprises the outer shell, the outer shell comprises a shell and a cap, the winding core is arranged in the shell, and the cap is arranged to cover the opening of the shell;

[0018] The winding core has a first end and a second end opposite to each other, the first end faces the opening of the shell, the pole ear is arranged at the first end, the connecting portion is connected to the cap, and / or the pole ear is arranged at the second end, and the connecting portion is connected to the bottom of the shell.

[0019] In a second aspect, an embodiment of the present application provides a method for preparing a battery, comprising the following steps:

[0020] S10, cutting the tab material to form an embedded portion with a length of L2 and a connecting portion with a length of L1, wherein the embedded portion and the connecting portion are connected to form a tab, wherein L2>L1;

[0021] S20, providing a pole piece provided with a hollow foil portion extending along a first direction, wherein the embedded portion is connected to a side surface of the hollow foil portion, and the connecting portion extends outside the pole piece;

[0022] S30, providing a diaphragm, wherein the diaphragm is stacked with the pole piece and the embedded portion is sandwiched between the diaphragm and the pole piece;

[0023] S40, the stacked diaphragms and the pole pieces are wound to form a winding core, and the connecting portion is located outside the winding core.

[0024] In one embodiment, the step of winding the stacked diaphragm and the pole piece to form a winding core comprises:

[0025] S41, winding the electrode piece with the side connected to the embedded portion as the inner side to form a winding core; or,

[0026] S42, winding the electrode sheet with the side of the electrode sheet facing away from the embedded portion as the inner side surface to form a winding core.

[0027] The battery provided by the embodiment of the present application has the following beneficial effects: compared with the related art, the battery of the present application includes a pole piece, a pole ear and a diaphragm; wherein, a hollow foil portion is provided on the pole piece, the pole ear is provided on the side of the hollow foil portion by an embedding portion, and the pole ear is connected to the outer shell of the battery by a connecting portion; the pole ear of the present application is formed by another process and then connected to the pole piece by an embedding portion, rather than being directly cut and formed on the pole piece, which directly saves the process of die-cutting the pole ear on the pole piece; and then directly connected to the outer shell by the connecting portion, thereby omitting the provision of a busbar, avoiding the formation of metal chips in the die-cutting and busbar welding processes, thereby reducing the defective rate of the battery voltage drop, while reducing the production cost and improving the production efficiency; and, setting the length L2 of the embedding portion to be greater than the length L1 of the connecting portion, increasing the connection area between the embedding portion and the hollow foil portion of the pole piece, reducing the resistance of the connection between the pole ear and the pole piece, and increasing the current passing between the pole piece and the pole ear; the embodiment of the present application also provides a method for preparing a battery, which has the above beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0029] Figure 1 A schematic diagram of the structure of a battery provided in one embodiment of the present application;

[0030] Figure 2 A schematic diagram of the flattened structure of the pole piece and the pole ear in the battery provided in one embodiment of the present application;

[0031] Figure 3A schematic diagram of the size structure of the pole piece and the pole ear in a battery provided in an embodiment of the present application;

[0032] Figure 4 A schematic diagram of a top view of a winding core in a battery provided in an embodiment of the present application;

[0033] Figure 5 A schematic diagram of the flattened structure of a pole piece and a pole ear in a battery provided in another embodiment of the present application;

[0034] Figure 6 A bottom view of the structure of a winding core in a battery provided in another embodiment of the present application;

[0035] Figure 7 A schematic diagram of the cross-sectional structure of a pole piece and a pole ear in a battery provided in another embodiment of the present application;

[0036] Figure 8 A schematic diagram of a process for preparing a battery provided in yet another embodiment of the present application;

[0037] Fig. 9 for Figure 8 Structural diagram of each process in the process;

[0038] Among them, the reference numerals in the figure are:

[0039] Battery 100; pole piece 10; pole ear 20; housing 30; winding core G;

[0040] Positive electrode sheet 11; negative electrode sheet 12; active material portion A; hollow foil portion B; positive electrode ear 21; negative electrode ear 22; embedded portion C; connecting portion D; first embedded portion C1; second embedded portion C2; first sub-portion D1; second sub-portion D2; housing 31; cap 32; first end G1; second end G2;

[0041] Second direction X; first direction Y. DETAILED DESCRIPTION

[0042] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0043] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0044] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to 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 application.

[0045] 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] Please also read Figures 1 to 4 , a battery 100 provided in an embodiment of the present application is now described.

[0047] like Figure 1 As shown, the battery 100 of the present application includes a pole piece 10, a pole ear 20, a diaphragm (not shown) and a housing 30. It should be noted that, in order to show the connection relationship between the pole ear 20 and the pole piece 10, Figure 1 Shown is a disassembled structural diagram of the cover cap 32 and the shell 31 of the housing 30 .

[0048] Optionally, there are at least two pole pieces 10 , at least two separators, and at least two pole tabs. The separator is used to separate the positive pole piece 11 from the negative pole piece 12 .

[0049] In this embodiment, the two electrode sheets 10 include a positive electrode sheet 11 and a negative electrode sheet 12. The positive electrode sheet 11 and the negative electrode sheet 12 are stacked. A separator is provided between the positive electrode sheet 11 and the negative electrode sheet 12, and another separator is provided on the outer side of the positive electrode sheet 11 and the negative electrode sheet 12 so that the positive electrode sheet 11 and the negative electrode sheet 12 are separated during subsequent winding. The positive electrode sheet 11, the separator and the negative electrode sheet 12 are stacked and wound into a winding core G. The winding core G has a first end G1 and a second end G2 opposite to each other in its height direction.

[0050] Optionally, in some other embodiments, there are multiple electrode sheets 10 and multiple separators. The multiple electrode sheets 10 include multiple positive electrode sheets 11 and multiple negative electrode sheets 12. The multiple positive electrode sheets 11 and the multiple negative electrode sheets 12 are alternately stacked, and a separator is arranged between each adjacent two positive electrode sheets 11 and negative electrode sheets 12. The positive electrode sheets 11, the separators, and the negative electrode sheets 12 are stacked and wound into a winding core G.

[0051] The battery 100 includes at least one positive electrode tab 21 and at least one negative electrode tab. The positive electrode tab 21 is disposed at a first end G1 in the height direction of the winding core G, and the negative electrode tab is disposed at a second end G2. The positive electrode tab 21 is connected to the positive electrode sheet 11, and the negative electrode tab is connected to the negative electrode sheet 12.

[0052] The positive electrode tab 21 is the tab 20 structure in the present application, and / or the negative electrode tab 22 is the tab 20 structure in the present application. In this embodiment, the positive electrode tab 21 is the tab 20 structure in the present application. In some other embodiments, the positive electrode tab 21 and the negative electrode tab 22 are both the tab 20 structure in the present application. The battery 100 of the present application is described below using this embodiment as an example.

[0053] It should be noted that in the finished battery 100, the positive electrode sheet 11, the positive electrode tab 21, the negative electrode sheet 12 and the separator are wound to form a winding core G. Figure 2 Schematic diagram of flattening the positive electrode sheet 11 and the positive electrode tab 21 in the battery 100 .

[0054] like Figure 1 and Figure 2 As shown, the positive electrode sheet 11 is provided with a hollow foil portion B extending along the first direction Y. The positive electrode tab 21 includes an embedded portion C and a connecting portion D, and at least a portion of the embedded portion C is arranged on the side of the hollow foil portion B. Specifically, the embedded portion C is connected to the hollow foil portion B of the positive electrode sheet 11 through a welding process. Optionally, the embedded portion C can be arranged on the first side of the hollow foil portion B, or on the second side of the hollow foil portion B. The connecting portion D is connected to the embedded portion C and extends outside the positive electrode sheet 11, and the connecting portion D is used to connect to the housing 30.

[0055] After the positive electrode sheet 11, the negative electrode sheet 12 and the separator are wound to form the core G, since the positive electrode sheet 11, the separator and the negative electrode sheet 12 are stacked, at least part of the embedded portion C is sandwiched between the adjacent positive electrode sheets 11 and the separator in the core G. It can be understood that the embedded portion C is sandwiched between the adjacent positive electrode sheets 11 and the separator. If the thickness of the embedded portion C is too large, it is easy to cause the shape of the core G formed by winding to be deformed and irregular. The embedded portion C is welded to the positive electrode sheet 11. If the thickness of the embedded portion C is too thin, it is easy to cause the embedded portion C to break when welding with the positive electrode sheet 11. Therefore, in this embodiment, the thickness of the embedded portion C is set to 10 microns (μm) to 50 microns, which ensures that the embedded portion C is normally welded with the positive electrode sheet 11 while making the shape of the core G formed by winding more regular. Optionally, the thickness of the embedded portion C may be 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm or 50μm, etc. Further, the thickness of the embedded portion C may be 20μm-30μm, specifically, 20μm, 21μm, 22μm, 23μm, 25μm, 26μm, 28μm, 29μm or 30μm, etc. In this embodiment, the embedded portion C with a thickness of 10μm-50μm is set, so that the cylindrical core G formed after winding is a relatively regular cylinder. In some other embodiments, the core G may also be an elliptical core G, and the embedded portion C with a thickness of 10μm-50μm is set, so that the core G formed after winding is a relatively regular elliptical cylinder.

[0056] Since the connection portion D is connected to the embedded portion C and extends outside the positive electrode sheet 11, after the positive electrode sheet 11, the negative electrode sheet 12 and the separator are wound to form the winding core G, the connection portion D extends outside the winding core G. It can be understood that the connection portion D extends outside the winding core G so that the connection portion D is connected to the outer shell 30, thereby transmitting electricity from the positive electrode sheet 11 to the outer shell 30.

[0057] like Figure 1 As shown, in this embodiment, the housing 30 includes a shell 31 and a cap 32. An open accommodating cavity is provided in the shell 31, and the opening is provided on the shell 31. The winding core G is provided in the accommodating cavity in a manner that the second end G2 faces the bottom of the shell 31 and the first end G1 faces the opening of the shell 31, and the cap 32 covers the opening of the shell 31. The positive electrode ear 21 is provided at the first end G1, and the positive electrode ear 21 is connected to the cap 32 through the connecting portion D. The specific connection method is welding, which can be a welding method such as ultrasonic welding or resistance welding.

[0058] In the embodiment of the present application, the pole ear 20 is arranged on the side of the hollow foil portion B through the embedded portion C, and is connected to the outer shell 30 of the battery 100 through the connecting portion D; the pole ear 20 of the embodiment of the present application is prepared and formed by another process and then connected to the pole piece 10 through the embedded portion C, rather than being directly cut and formed on the pole piece 10; and then directly connected to the outer shell 30 through the connecting portion D, thereby omitting the setting of the busbar, avoiding the formation of metal chips in the die-cutting and busbar welding processes, thereby reducing the defective rate of the voltage drop of the battery 100, while reducing the production cost and improving the production efficiency.

[0059] like Figure 3 As shown, in this embodiment, the length of the embedded portion C along the first direction Y is L2, and the length of the connecting portion D along the first direction Y is L1, wherein L2>L1. The embedded portion C is used to connect with the positive electrode sheet 11. The embedded portion C and the hollow foil portion B both extend along the first direction Y, and the length L2 of the embedded portion C is set to be greater than the length L1 of the connecting portion D, thereby increasing the connection area between the embedded portion C and the hollow foil portion B of the positive electrode sheet 11, reducing the resistance of the connection between the positive electrode tab 21 and the positive electrode sheet 11, and increasing the current passing between the positive electrode sheet 11 and the positive electrode tab 21.

[0060] Optionally, the length L2 of the embedded portion C is 4 mm to 15 mm, such as 4 mm, 5 mm, 6 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm or 15 mm, etc. The length L1 of the connecting portion D is 1 mm-5 mm, such as 1 mm, 2 mm, 3 mm, 4 mm or 5 mm, etc. As long as L2 is greater than L1.

[0061] Specifically, Figure 2 and Figure 3 As shown, the positive electrode sheet 11 also includes an active material portion A extending along the first direction Y, and the empty foil portion B is arranged on one side of the active material portion A along the second direction X. Among them, the active material portion A is the positive electrode active material portion A, which is formed by coating the positive electrode active material on the positive electrode sheet body. The empty foil portion B is the positive electrode sheet body exposed without coating the positive electrode active material, which is used for current collection and connection with the positive electrode ear 21. The second direction X is the arrangement direction of the active material portion A and the empty foil portion B, and is also the height direction of the winding core G. The active material portion A and the empty foil portion B both extend along the first direction Y, that is, the first direction Y is the length direction of the active material portion A and the length direction of the empty foil portion B. Among them, the first direction Y and the second direction X intersect. In this embodiment, the second direction X is perpendicular to the first direction Y.

[0062] In this embodiment, there are multiple positive electrode tabs 21. Each positive electrode tab 21 includes an embedded portion C and a connecting portion D connected to each other. The multiple embedded portions C are all extended along the first direction Y, that is, the first direction Y is the length direction of the embedded portion C. In the hollow foil portion B of the positive electrode sheet 11, the multiple embedded portions C are arranged along the first direction Y. The multiple connecting portions D extend along the second direction X to the side of the hollow foil portion B away from the active material portion A.

[0063] It can be understood that the empty foil portion B is arranged along the length direction of the positive electrode sheet 11, which can provide more area for connection with the positive electrode tab 21, so that multiple positive electrode tabs 21 can be arranged on the empty foil portion B. And because the empty foil portion B and the active material portion A are arranged in the height direction of the winding core G, the empty foil portion B is arranged on one side of the active material portion A in the second direction X, and after winding, the empty foil portion B forms a first end G1, so that multiple positive electrode tabs 21 are all arranged on the first end G1 of the winding core G, thereby facilitating the welding of multiple connection portions D and the cap 32.

[0064] Optional, such as Figure 5 As shown, in some embodiments, the negative electrode ear 22 is the ear 20 structure in the present application. The negative electrode sheet 12 includes an active material portion A and an empty foil portion B arranged on one side of the active material portion A along the second direction X. Among them, the active material portion A is the negative electrode active material portion A, which is formed by coating the negative electrode active material on the negative electrode sheet body. The empty foil portion B is the negative electrode sheet body exposed without coating the negative electrode active material, which is used for current collection and connection with the negative electrode ear 22. The empty foil portion B is arranged on one side of the active material portion A in the second direction X. After winding, the empty foil portion B forms a second end G2, so that multiple negative electrode ears 22 are arranged on the second end G2 of the winding core G, thereby facilitating the welding of multiple connecting portions D with the bottom of the shell 31. Specifically, the negative electrode ear 22 is welded to the bottom of the shell 31 through the connecting portion D. It should be noted that in this embodiment, it is not that the positive electrode ear is not provided, but the positive electrode ear in this embodiment does not adopt the ear structure of the present application, so it is not repeated here.

[0065] In some other embodiments, the positive electrode ear 21 and the negative electrode ear 22 are both the electrode ear 20 structure in the present application. The empty foil portion B in the positive electrode sheet 11 and the empty foil portion B in the negative electrode sheet 12 are arranged on opposite sides to form the first end G1 and the second end G2 respectively. The positive electrode ear 21 is arranged at the first end G1, and the negative electrode ear 22 is arranged at the second end G2. Both the positive electrode ear 21 and the negative electrode ear 22 are provided with a connecting portion D. The positive electrode ear 21 is welded to the cap 32 through the connecting portion D, and the negative electrode ear 22 is welded to the bottom of the shell 31 through the connecting portion D.

[0066] Optionally, the battery 100 is provided with 5 to 20 positive pole ears 21, for example, 5, 6, 8, 10, 12, 13, 15, 16, 18 or 20. 10-15 positive pole ears 21 are provided, and the length L1 of the connection portion D in each corresponding positive pole ear 21 is 1mm-3mm. 5-10 positive pole ears 21 are provided, and the length L1 of the connection portion D in the corresponding positive pole ear 21 is 3mm-5mm. In this embodiment, the connection portion D of multiple positive pole ears 21 is welded on the cap 32. It can be understood that the more the number of positive pole ears 21, the larger the volume of the connection formed by the connection of multiple positive pole ears 21 and the cap 32, so that the internal resistance of the connection of multiple positive pole ears 21 and the cap 32 is smaller. At the same time, it can also be understood that when more positive pole ears 21 are provided, the smaller the length L1 of the connection portion D is, the smaller the total occupied space of the positive pole ears 21 is.

[0067] Optionally, the thickness of the connection portion D is 50 μm-100 μm, for example, 50 μm, 55 μm, 56 μm, 60 μm, 65 μm, 68 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, etc. Providing a connection portion D with a larger thickness can further reduce the internal resistance of the connection between the positive electrode tab 21 and the cap 32. Furthermore, setting the thickness of the connection portion D to be greater than the thickness of the embedded portion C, on the one hand, facilitates the embedded portion C to be clamped in the winding core G, and on the other hand, can reduce the internal resistance of the positive electrode tab 21 as a whole, thereby reducing the internal resistance of the battery 100.

[0068] Optionally, in some other embodiments, the connection portion D includes a first sub-portion and a second sub-portion. The second sub-portion is connected between the first sub-portion and the embedded portion C. The thickness of the embedded portion C is less than the thickness of the first sub-portion. The thickness of the second sub-portion gradually increases along the connection direction of the embedded portion C, the second sub-portion and the first sub-portion. The sudden change in thickness of the connection portion D and the embedded portion C will cause a large stress at the connection between the connection portion D and the embedded portion C. The thickness of the second sub-portion is set to gradually increase from close to the embedded portion C to close to the first sub-portion, so as to achieve a gradual change in the thickness of the connection portion D and the embedded portion C, thereby reducing the stress at the connection between the connection portion D and the embedded portion C.

[0069] Please continue reading Figure 2 and Figure 3. The height of the connecting portion D is H1, the height of the embedded portion C is H2, and the height of the empty foil portion B is H3. The height H1 of the connecting portion D is 8mm-26mm, for example, 8mm, 10mm, 12mm, 15mm, 18mm, 20mm, 22mm, 25mm or 26mm, etc. The height H1 of the connecting portion D is affected by the height of the winding core G and the design of the outer shell 30. In the present embodiment, the model specification of the battery 100 is 18650, and the height H1 of the connecting portion D is 14.8mm. The height H2 of the embedded portion C is affected by the height H3 of the empty foil portion B. In the present embodiment, H2>0 and H2 satisfies H2=H3±1mm. The height H3 of the empty foil portion B is 1mm-5mm, for example, 1mm, 2mm, 3mm, 4mm or 5mm, etc. The height H2 of the embedded portion C is 0.5mm-6mm, for example, 0.5mm, 1mm, 2mm, 5mm or 6mm, etc.

[0070] It can be understood that by setting H2=H3±1 mm, when the length L2 of the embedded portion C and the height H3 of the hollow foil portion B are constant, a larger height H2 of the embedded portion C can be set to increase the connection area between the embedded portion C and the hollow foil portion B as much as possible.

[0071] It should be noted that in actual products, due to the limitation of process precision, the embedded portion C may be completely sandwiched between the positive electrode sheet 11 and the separator, or part of the embedded portion C may be sandwiched between the positive electrode sheet 11 and the separator, and another part of the embedded portion C may protrude from the positive electrode sheet 11, such as Figure 1 shown.

[0072] After the positive electrode ear 21 is connected to the side of the positive electrode sheet 11, the positive electrode ear 21 is wound into a winding core G along with the positive electrode sheet 11, the negative electrode sheet 12 and the separator. It can be understood that when the embedded portion C is set at a position close to the axis O of the winding core G, the length L2 of the embedded portion C is set too large, so that the embedded portion C is too large or even overlapped, affecting the winding. If the length L2 of the embedded portion C is set too small, the connection area with the positive electrode sheet 11 is too small. That is, the length L2 of the embedded portion C is related to the position of the axis O of the embedded portion C around the winding core G. Figure 4 As shown, in this embodiment, L2=A·2πr, where r is the radius of the axis O of the embedded portion C around the winding core G, π is the circumference, A is the proportional coefficient, and the value range of A is [0.25, 0.33]. That is, the value range of A is 0.25-0.33, such as 0.25, 0.26, 0.28, 0.29, 0.3, 0.31 or 0.33. By setting L2=A·2πr, the connection area between the embedded portion C and the positive electrode sheet 11 is ensured while reducing the influence of the length L2 of the embedded portion C on the winding.

[0073] For example, an embedded portion C is disposed at a radius r of 6 mm from the axis O of the winding core G. Corresponding to the value range of A, the value range of L2 is 9.4 mm-12.4 mm. In this embodiment, the length L2 of the embedded portion C with r of 6 mm is 12 mm.

[0074] Please continue reading Figure 4 In this embodiment, the embedding portion C of the positive electrode tab 11 is disposed on the inner side of the positive electrode sheet 11 close to the axis O of the winding core G. Optionally, in some embodiments, the embedding portion C of the negative electrode tab 22 is disposed on the outer side of the negative electrode sheet 12 away from the axis O of the winding core G, such as Figure 6 As shown. In some other embodiments, each positive electrode tab 21 is provided with two embedded portions C, one embedded portion C is provided on the inner side of the positive electrode sheet 11 close to the axis O of the winding core G, and the other embedded portion C is provided on the outer side of the positive electrode sheet 11 away from the axis O of the winding core G. Optionally, in some embodiments, the embedded portions C of some positive electrode tabs 21 are provided on the inner side of the positive electrode sheet 11 close to the axis O of the winding core G, and the embedded portions C of some positive electrode tabs 21 are provided on the outer side of the positive electrode sheet 11 away from the axis O of the winding core G, as long as the embedded portions C are provided on the side of the positive electrode sheet 11 to achieve the connection between the positive electrode tab 21 and the positive electrode sheet 11.

[0075] See also Figure 7 The structure of this embodiment is similar to Figure 1 The structures of the embodiments are roughly the same. Figure 1 The difference between the embodiments lies in the specific structural arrangement of the positive electrode tab 21 and the hollow foil portion B.

[0076] like Figure 7 As shown, a positive electrode ear 21 has two embedded parts C, namely a first embedded part C1 and a second embedded part C2. The first embedded part C1 and the second embedded part C2 are respectively arranged on the inner side surface of the axis O close to the winding core G and the outer side surface away from the axis O of the winding core G of the same positive electrode sheet 11. Specifically, the first embedded part C1 is arranged on the inner side surface of the positive electrode sheet 11 close to the axis O of the winding core G, and the second embedded part C2 is arranged on the outer side surface of the positive electrode sheet 10 away from the axis O of the winding core G.

[0077] By providing two embedded parts C to be clamped on the positive electrode sheet 11 , the reliability of the connection between the embedded parts C and the positive electrode sheet 11 can be enhanced, and the connection area between the positive electrode tab 21 and the positive electrode sheet 11 can be further increased through double-sided contact.

[0078] Optionally, the first embedded portion C1 and the second embedded portion C2 have the same thickness and their total thickness is between 10 μm and 50 μm, so that the cylindrical winding core G formed after winding is a relatively regular cylinder.

[0079] Optionally, a plurality of grooves (not shown) are provided on the hollow foil portion B to thin the hollow foil portion B. The embedded portion C is correspondingly arranged in the groove, thereby further reducing the influence of the embedded portion C sandwiched between the positive electrode sheet 11 and the separator on the winding. Optionally, the thickness of the embedded portion C is equal to the depth of the groove, so that the surface formed by the connection between the embedded portion C and the positive electrode sheet 11 is smoother.

[0080] Optionally, in some other embodiments, a negative electrode ear 22 has two embedded portions C, namely a first embedded portion C1 and a second embedded portion C2. The first embedded portion C1 and the second embedded portion C2 are respectively arranged on the inner side surface of the same negative electrode sheet 12 close to the axis O of the winding core G and the outer side surface away from the axis O of the winding core G. Specifically, the first embedded portion C1 is arranged on the inner side surface of the negative electrode sheet 12 close to the axis O of the winding core G, and the second embedded portion C2 is arranged on the outer side surface of the negative electrode sheet 12 away from the axis O of the winding core G.

[0081] The remaining structures of this embodiment are Figure 1 The remaining structures of the embodiment are similar and will not be described here in detail.

[0082] Please also read Figure 8 and Fig. 9 The embodiment of the present application also provides a method for preparing a battery 100, which is used to prepare the battery 100 provided in the embodiment of the present application.

[0083] The method for preparing the battery 100 comprises the following steps:

[0084] Step S10, cutting the tab material to form an embedding portion C with a length of L2 and a connecting portion D with a length of L1. The embedding portion C and the connecting portion D are connected to form the tab 20, wherein L2>L1.

[0085] Step S20 , providing a pole piece 10 provided with a hollow foil portion B extending along a first direction Y, wherein the embedded portion C is connected to a side surface of the hollow foil portion B, and the connecting portion D extends to the outside of the pole piece 10 .

[0086] Step S30 , providing a diaphragm, laminating the diaphragm and the pole piece 10 , and sandwiching the embedded portion C between the diaphragm and the pole piece 10 .

[0087] In step S40 , the stacked diaphragms and the electrode sheets 10 are wound to form a winding core G, and the connecting portion D is located outside the winding core G.

[0088] The following is prepared Figure 1 Taking the battery 100 provided in the embodiment as an example, the preparation method of the battery 100 is described.

[0089] Step S10, cutting the positive electrode tab material to form an embedding portion C with a length of L2 and a connecting portion D with a length of L1. The embedding portion C and the connecting portion D are connected to form the positive electrode tab 21, wherein L2>L1.

[0090] Specifically, the embedded portion C and the connecting portion D are integrally formed and formed by cutting. Optionally, the length L2 of the embedded portion C is 4 mm-15 mm, such as 4 mm, 5 mm, 6 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm or 15 mm. The length L1 of the connecting portion D is 1 mm-5 mm, such as 1 mm, 2 mm, 3 mm, 4 mm or 5 mm. As long as L2 is greater than L1, it will be fine.

[0091] The formed positive electrode tab 21 has a larger connection area with the positive electrode sheet 11 , a smaller connection resistance, and a larger current flow between the positive electrode sheet 11 and the positive electrode tab 21 .

[0092] Optionally, the thickness of the embedded portion C may be 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm or 50 μm, etc. The thickness of the connecting portion D is 50 μm-100 μm, such as 50 μm, 55 μm, 56 μm, 60 μm, 65 μm, 68 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm or 100 μm, etc. The height H1 of the connecting portion D is 8 mm-26 mm, such as 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm or 26 mm, etc. The height H2 of the embedded portion C is 0.5 mm-6 mm, such as 0.5 mm, 1 mm, 2 mm, 5 mm or 6 mm, etc.

[0093] Next, in step S20 , a positive electrode sheet 11 having a hollow foil portion B extending along a first direction Y is provided, the embedded portion C is connected to a side surface of the hollow foil portion B, and the connecting portion D extends to the outside of the positive electrode sheet 11 .

[0094] Specifically, a positive electrode active material is coated on the lower part of a positive electrode sheet body in the height direction to form an active material part A, and a 1mm-5mm area on the upper part of the positive electrode sheet body is reserved without being coated with the positive electrode active material, exposing the positive electrode sheet body to form a hollow foil part B, and the hollow foil part B plays a current collecting role to be connected to the positive electrode ear 21.

[0095] In this embodiment, the embedded portion C is connected to the hollow foil portion B on one side of the positive electrode sheet 11 , and the connecting portion D extends to a side of the hollow foil portion B away from the active material portion A.

[0096] Specifically, the positive electrode tab 21 is positioned on the empty foil portion B of the positive electrode sheet 11 according to the thickness of the winding frame and the positive electrode sheet 11, the thickness of the negative electrode sheet 12, and the thickness of the separator, and the welding portion between the embedded portion C and the empty foil portion B is attached and flattened so that the empty foil portion B is completely attached to the embedded portion C, and the embedded portion C and the empty foil portion B are welded. If multiple positive electrode tabs 21 are welded to the empty foil portion B, the multiple positive electrode tabs 21 are positioned and welded one by one.

[0097] It should be noted that the positive electrode tab 21 is positioned on the empty foil portion B of the positive electrode sheet 11 according to the winding frame so that the embedded portion C is located on the set radius r of the winding core G after subsequent winding.

[0098] Optionally, in some embodiments, the hollow foil portion B of the positive electrode sheet 11 needs to be thinned before welding the embedded portion C to form a plurality of grooves, and one embedded portion C is correspondingly welded in one groove. Optionally, the battery 100 is provided with 5 to 20 embedded portions C, and the corresponding hollow foil portion B is provided with 5 to 20 grooves.

[0099] Next, the operation of step S30 is performed to provide a separator, and the separator is stacked with the positive electrode sheet 11 and the embedded portion C is sandwiched between the separator and the positive electrode sheet 11. Specifically, a separator is provided between the positive electrode sheet 11 and the negative electrode sheet 12, and another separator is provided on the outer side of the positive electrode sheet 11 and the negative electrode sheet 12 to separate the positive electrode sheet 11 and the negative electrode sheet 12 during subsequent winding.

[0100] Next, the operation of step S40 is performed, and the stacked separator, the positive electrode sheet 11, and the negative electrode sheet 12 are wound to form a core G, and the connection portion D is located outside the core G. The formed core G has a first end G1 and a second end G2 opposite to each other in its height direction. The end of the positive electrode ear 21 extending out is the first end G1. Since the connection portion D extends outside the positive electrode sheet 11, after the positive electrode sheet 11, the negative electrode sheet 12 and the separator are wound to form the core G, the connection portion D is located outside the first end G1 of the core G.

[0101] Optionally, step S40 includes step S41 or step S42.

[0102] In this embodiment, step S40 also includes step S41.

[0103] In S41 , the positive electrode sheet 11 is wound with the surface connected to the embedding portion C as the inner surface, so as to form a winding core G.

[0104] In other embodiments, step S40 of the preparation method may include step S42.

[0105] S42 , the positive electrode sheet 11 is wound with the side facing away from the embedding portion C as the inner side surface, so as to form a winding core G.

[0106] Optionally, after step S40, step S50 and step S60 may be included in sequence.

[0107] S50, providing a housing 31, and installing one end of the core G with the positive electrode ear 21 facing outward in the housing 31. Specifically, the positive electrode ear 21 is arranged at the first end G1. The second end G2 of the core G faces the bottom of the housing 31, and the first end G1 faces outward in the accommodation cavity of the housing 31. The first end G1 of the core G faces the opening of the housing 31.

[0108] S60, providing a cap 32, connecting portion D is connected to the cap 32, and the cap 32 is covered on the opening of the shell 31 to form the outer shell 30. The connecting portions D of the plurality of positive tabs 21 are welded and connected to the cap 32, and the cap 32 is covered on the opening of the shell 31, and the preparation of the battery 100 is completed.

[0109] Optionally, in some embodiments, the negative electrode tab 22 is the tab 20 structure in the present application. Accordingly, the preparation method of the battery 100 includes:

[0110] Step S10, cutting the negative electrode tab material to form an embedding portion C with a length of L2 and a connecting portion D with a length of L1. The embedding portion C and the connecting portion D are connected to form the negative electrode tab 22, wherein L2>L1.

[0111] Step S20, providing a negative electrode sheet 12 provided with a hollow foil portion B extending along a first direction Y, wherein the embedded portion C is connected to the side of the hollow foil portion B, and the connecting portion D extends to the outside of the negative electrode sheet 12. Specifically, a negative electrode active material is coated on the upper portion of a negative electrode sheet body in the height direction to form an active material portion A, and a 1mm-5mm area is reserved at the lower portion of the negative electrode sheet body without coating the negative electrode active material, exposing the negative electrode sheet body to form a hollow foil portion B, and the hollow foil portion B plays a current collecting role to be connected to the negative electrode ear 22.

[0112] In step S30 , a separator is provided. The separator and the negative electrode sheet 12 are stacked and the embedded portion C is sandwiched between the separator and the negative electrode sheet 12 .

[0113] In step S40, the stacked separator and the negative electrode sheet 12 are wound to form a winding core G, and the connecting portion D is located outside the winding core. Specifically, the formed winding core G has a first end G1 and a second end G2 opposite to each other in its height direction. The end from which the negative electrode ear 22 extends is the second end G2. Since the connecting portion D extends outside the negative electrode sheet 12, after the positive electrode sheet 11, the negative electrode sheet 12 and the separator are wound to form the winding core G, the connecting portion D is located outside the second end G2 of the winding core G.

[0114] S50, provide a shell 31, one end of the negative electrode ear 22 provided on the core G faces the bottom of the shell 31, the connection portion D of the negative electrode ear 22 is connected to the bottom of the shell 31, and the core G is installed in the shell 31. Specifically, the negative electrode ear 22 is provided at the second end G2. The second end G2 of the core G faces the bottom of the shell 31, and the connection portions D of the multiple negative electrode ears 22 are welded to the bottom of the shell 31. The core G is installed in the accommodating cavity of the shell 31.

[0115] S60, providing a cap 32, and the cap 32 is covered on the opening of the shell 31 to form the outer shell 30. Specifically, the cap 32 is covered on the opening of the shell 31, and the preparation of the battery 100 is completed.

[0116] The above is a description of the battery 100 and the preparation method thereof provided in the embodiment of the present application.

[0117] The battery provided in the embodiment of the present application includes a pole piece, a pole ear and a diaphragm; wherein a hollow foil portion is provided on the pole piece, the pole ear is provided on the side of the hollow foil portion through an embedding portion, and the pole ear is connected to the battery shell through a connecting portion; the pole ear of the present application is prepared and formed by another process and then connected to the pole piece through the embedding portion, rather than being directly cut and formed on the pole piece, which directly saves the process of die-cutting the pole ear on the pole piece; and then directly connected to the shell through the connecting portion, thereby omitting the provision of a busbar, avoiding the formation of metal chips in the die-cutting and busbar welding processes, thereby reducing the defective rate of battery voltage drop, while reducing production costs and improving production efficiency; and, setting the length L2 of the embedding portion to be greater than the length L1 of the connecting portion, thereby increasing the connection area between the embedding portion and the hollow foil portion of the pole piece, reducing the resistance of the connection between the pole ear and the pole piece, and increasing the current passing between the pole piece and the pole ear; the embodiment of the present application also provides a method for preparing a battery, which has the above-mentioned beneficial effects.

[0118] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A battery, characterized in that: include: A pole piece, wherein the pole piece is provided with a hollow foil portion extending along a first direction; A diaphragm, wherein the diaphragm and the pole piece are stacked and wound into a winding core; and The pole ear comprises an embedded portion and a connecting portion, wherein at least a portion of the embedded portion is sandwiched between the pole piece and the diaphragm adjacently arranged in the winding core and connected to the side of the hollow foil portion of the pole piece, the connecting portion is connected to the embedded portion and extends outside the winding core, and the connecting portion is used to be connected to the housing; The length of the embedded portion along the first direction is L2, and the length of the connecting portion along the first direction is L1, wherein L2>L1.

2. The battery according to claim 1, characterized in that L2=A·2πr, wherein r is the radius of the embedded portion around the axis of the winding core, A is the proportional coefficient, and the value range of A is [0.25, 0.33].

3. The battery according to claim 1, characterized in that The embedded portion is arranged on the inner side surface of the pole piece close to the axis of the winding core; or, The embedded portion is arranged on the outer side surface of the pole piece away from the axis of the winding core.

4. The battery according to claim 1, characterized in that The pole lug has a first embedding portion and a second embedding portion, and the first embedding portion and the second embedding portion are respectively arranged on the inner side surface close to the axis of the winding core and the outer side surface away from the axis of the winding core of the same pole piece.

5. The battery according to claim 1, characterized in that The pole piece further comprises an active material portion extending along the first direction, the active material portion and the hollow foil portion are arranged along a second direction, and the second direction intersects with the first direction; There are multiple pole ears, each of which includes the embedded part and the connecting part connected to each other, the multiple embedded parts extend along the first direction and are arranged in the hollow foil part along the first direction, and the multiple connecting parts extend to the side of the hollow foil part away from the active material part.

6. The battery according to claim 5, characterized in that The hollow foil portion is provided with a plurality of grooves, the embedded portions are correspondingly arranged in the grooves, and the thickness of the embedded portions is equal to the depth of the grooves.

7. The battery according to claim 1, characterized in that The connecting portion includes a first sub-portion and a second sub-portion, the second sub-portion is connected between the first sub-portion and the embedded portion, the thickness of the embedded portion is smaller than the thickness of the first sub-portion, and the thickness of the second sub-portion gradually increases along the connecting direction of the embedded portion, the second sub-portion and the first sub-portion.

8. The battery according to claim 1, characterized in that The battery further comprises the outer shell, the outer shell comprises a shell and a cap, the winding core is arranged in the shell, and the cap is arranged to cover the opening of the shell; The winding core has a first end and a second end opposite to each other, the first end faces the opening of the shell, the pole ear is arranged at the first end, the connecting portion is connected to the cap, and / or the pole ear is arranged at the second end, and the connecting portion is connected to the bottom of the shell.

9. A method for preparing a battery, characterized in that: The following steps are involved: S10, cutting the tab material to form an embedded portion with a length of L2 and a connecting portion with a length of L1, wherein the embedded portion and the connecting portion are connected to form a tab, wherein L2>L1; S20, providing a pole piece provided with a hollow foil portion extending along a first direction, wherein the embedded portion is connected to a side surface of the hollow foil portion, and the connecting portion extends outside the pole piece; S30, providing a diaphragm, wherein the diaphragm is stacked with the pole piece and the embedded portion is sandwiched between the diaphragm and the pole piece; S40, the stacked diaphragms and the pole pieces are wound to form a winding core, and the connecting portion is located outside the winding core.

10. The method for preparing a battery according to claim 9, characterized in that: The step of winding the stacked diaphragm and the pole piece to form a winding core comprises: S41, winding the electrode piece with the side connected to the embedded portion as the inner side to form a winding core; or, S42, winding the electrode sheet with the side of the electrode sheet facing away from the embedded portion as the inner side surface to form a winding core.

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