Button battery pole piece, button battery and preparation method thereof

Abstract

The present invention provides a button cell electrode, a button cell and a preparation method thereof, wherein the electrode comprises a current collector; a pole ear, a pole ear glue is provided, one end of the pole ear has a welding area, and the pole ear is welded to the current collector through the welding area; wherein at least a portion of the pole ear glue overlaps with the current collector, and a bendable flexible portion is formed between the welding area and the pole ear glue. Compared with the prior art, in the button cell of the present invention, at least a portion of the pole ear glue overlaps with the current collector, and the welding area of ​​the pole ear is arranged at the end position, thereby forming a flexible portion between the welding area and the pole ear glue for bending, and the arrangement of the flexible portion avoids the risk of the aluminum-plastic film being squeezed and ruptured due to the formation of a sharp angle when the pole ear is bent from the top, and at the same time, the pole ear is directly bent in the flexible portion area, which completely solves the problem of leakage and inflation caused by the puncture of the aluminum-plastic film.

Description

Technical Field

[0001] The invention relates to the field of button batteries, and in particular to a pole piece for a button battery, a button battery and a preparation method thereof. Background Art

[0002] Button batteries usually include a cover, a shell and a battery cell. The battery cell is placed in the shell, and the cover and the shell are snapped together to form a closed space. Existing button batteries generally have the following two packaging methods, including hard shell packaging and soft package packaging. Among them, the hard shell packaging method mainly adopts the method of physical blocking and hard shell, but this packaging effect is not stable. For example, if the electrolyte is directly injected into the shell, there is a risk of electrolyte leakage. While using soft package packaging, such as Figure 1 As shown, the positive and negative tabs of the wound battery cell are usually located longitudinally at the head of the battery cell. When the aluminum-plastic film is packaged, the tabs are first folded to both sides for the first bend, wherein the first bend is usually folded from the top of the aluminum-plastic film. After the packaging is completed, the tabs are bent back to a position parallel to the longitudinal direction of the battery cell head. Therefore, conventional tab glue is set on the periphery of the pole piece, and a part of the tab area is reserved between the tab glue and the pole piece for the first bend. However, this packaging structure still has the following problems:

[0003] First, the tabs are usually metal strips with a thickness of 0.1 to 0.2 mm, with sharp corners at the bends. The aluminum-plastic film can be easily squeezed and ruptured during the first bend, creating the risk of leakage and inflation, and the appearance is not beautiful.

[0004] Second, the first time the tab is bent, it is encapsulated in the aluminum-plastic film, and then it is bent back from the edge of the aluminum-plastic film. The bent part will form a pointed arch area, which changes the shape of the battery cell from round to elliptical, which not only causes the diameter of the battery cell to increase by at least 0.4mm, but also reduces the effective utilization of space; at the same time, the elliptical structure increases the difficulty of the subsequent edge cutting process and reduces the product qualification rate.

[0005] In view of this, it is indeed necessary to provide a technical solution to the above problems. Summary of the invention

[0006] One of the purposes of the present invention is to provide a pole piece for a button battery, so as to solve the problem that the bending part of the pole ear of the existing soft-pack button battery is easy to squeeze the aluminum-plastic film and cause leakage and inflation.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A button battery electrode, comprising:

[0009] current collector;

[0010] A pole ear, provided with a pole ear glue, one end of the pole ear having a welding area, and the pole ear is welded to the current collector through the welding area;

[0011] Wherein, at least a portion of the tab glue overlaps with the current collector, and a bendable flexible portion is formed between the welding area and the tab glue.

[0012] In the button battery of the present invention, at least a part of the pole ear glue is arranged to overlap with the current collector, and the welding area of ​​the pole ear is arranged at the end position, so that a flexible portion can be formed between the welding area and the pole ear glue for bending, and the arrangement of the flexible portion ensures that the pole ear is directly bent horizontally and the height of the bending part is lower than the battery cell. That is, when the aluminum-plastic film is packaged, the part where the pole ear glue overlaps with the current collector will be bent and led out from the side of the aluminum-plastic film, thus avoiding the aluminum-plastic film being squeezed and broken due to the pole ear bending from the top to form a sharp corner area. Compared with the conventional button battery in which the pole ear glue is arranged outside the current collector and the pole ear area between the pole ear glue and the current collector is bent, the pole piece used in this button battery completely solves the problem of leakage and inflation caused by the aluminum-plastic film being squeezed out at the bending part of the pole ear, and the bending part is directly led out from the side, which greatly avoids the problem of easy breakage at the bending part caused by the aluminum-plastic film or external extrusion.

[0013] Preferably, the tab glue has a first side, which is a side of the tab glue and the welding area facing each other; the current collector has a second side, which is a long side close to the tab lead-out end; the distance between the first side and the second side is greater than or equal to 0.5 mm, and less than the width of the current collector. Setting the width of the overlapping area of ​​the tab glue and the current collector to at least 0.5 mm can ensure that the tab has enough bending area, so that there is enough distance between its lead-out point and the aluminum-plastic film, and further avoid the situation where the aluminum-plastic film is squeezed and broken due to the bending at the top.

[0014] Preferably, the distance between the first side and the second side is 0.5 to 5 mm. More preferably, the distance between the first side and the second side is 1 mm. The inventors have repeatedly conducted experiments on a large number of button batteries of different shapes, models, and capacities and found that when the distance between the first side and the second side is 1 mm, that is, the length of the overlapping area between the ear glue and the current collector is 1 mm, the performance of the button battery is even better, indicating that at this distance, not only can the problem of the aluminum-plastic film being squeezed out be avoided, but it can also help increase the energy density of the battery.

[0015] Preferably, the welding area is formed with a welding spot array, the welding spot diameter is 0.01-0.5mm, and the spacing between two adjacent welding spots is 0.01-1mm. By reducing the welding spot diameter of the welding area to less than 0.5mm and reducing the spacing between the welding spots, while ensuring sufficient contact between the pole ear and the current collector, it can also prevent the welding head from falling off due to long-term use of the button battery, effectively improving the reliability of the connection between the pole ear and the pole piece. In addition, such a setting increases the current concentrated on the surface, making the conductivity of the battery even better.

[0016] The existing button battery is bent through the outer area of ​​the current collector, and the problem of adjusting the size and distance of the welding point is not considered; at the same time, due to the high hardness of the ear glue, it is difficult to bend, and the general design will also move the ear glue outside the current collector. The inventor broke the conventional design idea, making the ear glue overlap with the current collector at least in part, and using the ear glue and the welding area for positioning, so that the ear can be directly bent from the flexible part and directly led out from the side of the aluminum-plastic film, without bypassing the top of the aluminum-plastic film and then leading out, thereby avoiding the risk of puncturing the aluminum-plastic film due to the sharp corners formed by leading out from the top.

[0017] The second object of the present invention is to provide a button battery, comprising a battery core formed by winding the electrode sheet as described in any one of the above items and an aluminum-plastic film wrapped around the battery core, the aluminum-plastic film comprising a first aluminum-plastic film sheet and a second aluminum-plastic film sheet, the electrode ear is horizontally bent through the flexible portion and extends outward along the covering portion of the first aluminum-plastic film sheet and the second aluminum-plastic film sheet.

[0018] The button battery of the present invention not only solves the hidden risk of the sharp corners brought by the top bending area piercing the aluminum-plastic film; at the same time, the pole ear is directly led out from the side of the aluminum-plastic film, and there is no sharp corner that causes the diameter of the battery cell to increase, which can increase the effective utilization space of the button battery to a greater extent and maximize the capacity; in addition, when the pole ear is trimmed after the aluminum-plastic film is wrapped, the battery cell will not change from a round shape to an elliptical shape due to the increase in diameter, which reduces the difficulty of the trimming process, improves the qualified rate of the product, and makes the battery more beautiful as a whole.

[0019] Preferably, the distance between the outwardly extending pole ear and the top end of the first aluminum-plastic film is a, and the distance between the outwardly extending pole ear and the bottom end of the second aluminum-plastic film is b, and a:b=(1-20):(20-1).

[0020] Preferably, the outer ring of the battery cell is also covered with an insulating film, and the insulating film covers the welding area; the width of the insulating film is substantially equal to the height of the welding area. Compared with the traditional full covering situation, the present invention winds the insulating film around the welding area, that is, the insulating film is arranged close to the flexible part. When the flexible part is bent, the insulating film can also play a positioning role to help the flexible part bend better. Specifically, the insulating film can be covered with green glue.

[0021] Preferably, the electrode sheet includes a positive electrode sheet and a negative electrode sheet, the electrode tab includes a positive electrode tab and a negative electrode tab, the positive electrode tab is electrically connected to the positive electrode sheet, the negative electrode tab is electrically connected to the negative electrode sheet, and the angle between the positive electrode tab and the negative electrode tab relative to the connecting line of the winding center is 0 to 180°. The positive electrode tab is connected to one end of the positive electrode sheet of the outermost circle of the battery cell away from the axis of the battery cell, and the negative electrode tab is connected to one end of the negative electrode sheet of the outermost circle of the battery cell away from the axis of the battery cell.

[0022] Preferably, the lengths of the negative electrode sheet and the positive electrode sheet at the outermost circle of the battery cell are different. By staggering the lengths, the positive and negative electrode tabs can be adapted to the specific shape of the button battery and can be led out from any direction and angle. For example, the angle between the positive and negative electrode tabs and the line connecting the winding center can be 30°, 60°, 90°, 180°, etc., and is of course not limited to the angles explicitly stated.

[0023] The third object of the present invention is to provide a method for preparing a button battery, comprising the following steps:

[0024] Welding the electrode tab to the current collector through the welding area;

[0025] Applying the tab glue to the tab and close to the welding area, so that at least a portion of the tab glue overlaps with the current collector, and a flexible portion is reserved between the welding area and the tab glue;

[0026] Performing pit punching treatment on the first aluminum-plastic film and the second aluminum-plastic film respectively;

[0027] Placing the battery core in the concave pit of the second aluminum-plastic film, and then covering the first aluminum-plastic film along the direction of the second aluminum-plastic film, so that the tab is horizontally bent from the flexible portion and extends outward along the covering portion of the first aluminum-plastic film and the second aluminum-plastic film, thereby completing the packaging of the aluminum-plastic film;

[0028] After packaging is completed, the tabs are folded back to complete the preparation of the button cell.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] 1) A button cell electrode provided by the present invention comprises a current collector; a pole ear, provided with a pole ear glue, one end of the pole ear having a welding area, and the pole ear is welded to the current collector through the welding area; wherein at least a portion of the pole ear glue overlaps with the current collector, and a bendable flexible portion is formed between the welding area and the pole ear glue. Compared with conventional button cells in which the pole ear glue is arranged outside the current collector and the pole ear region between the pole ear glue and the current collector is bent, the button cell electrode of the present invention arranges at least a portion of the pole ear glue to overlap with the current collector, and the welding area of ​​the pole ear is arranged at the end position, thereby forming a bendable flexible portion between the welding area and the pole ear glue, and the arrangement of the flexible portion ensures that the pole ear is directly bent horizontally and the height of the bending point is lower than the battery cell. In this way, during the aluminum-plastic film packaging, the tabs are directly bent from the flexible portion and led out from the side of the aluminum-plastic film, avoiding the risk of the aluminum-plastic film being squeezed and broken due to the sharp corner area formed by the tabs being bent from the top. It also completely solves the problem that the bending part of the tabs of the existing soft-pack button battery is easy to squeeze the aluminum-plastic film and cause leakage and inflation.

[0031] 2) The present invention also provides a button battery, comprising a battery core wound by the above-mentioned pole piece and an aluminum-plastic film wrapped outside the battery core, wherein the aluminum-plastic film comprises a first aluminum-plastic film sheet and a second aluminum-plastic film sheet, and the pole ear is horizontally bent through the flexible portion and extends outward along the cover of the first aluminum-plastic film sheet and the second aluminum-plastic film sheet. The button battery of the present invention not only solves the risk of piercing the aluminum-plastic film due to the sharp corners brought by the top bending area; at the same time, it is directly led out from the side of the aluminum-plastic film, so that the bending part of the pole ear is infinitely close to the battery core, and there is no situation where the diameter of the battery core increases due to the sharp corners, which can increase the effective utilization space of the button battery to a greater extent and maximize the capacity; in addition, when the pole ear is trimmed after the aluminum-plastic film is wrapped, the battery core will not change from a round shape to an elliptical shape due to the increase in diameter, which reduces the process difficulty of trimming, improves the qualified rate of the product, and makes the battery more beautiful as a whole.

[0032] 3) The present invention also provides a method for preparing the battery, which simplifies the preparation of the battery, solves the existing problems and facilitates industrial mass production, thus providing the possibility for the widespread application of button batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the structure of an existing button battery after winding.

[0034] Figure 2 It is a schematic diagram of the structure of the pole piece of the present invention.

[0035] Figure 3 This is one of the structural schematic diagrams of the button battery after winding.

[0036] Figure 4 It is a cross-sectional schematic diagram of the button battery of the present invention after winding.

[0037] Figure 5 This is the second structural schematic diagram of the button battery after winding of the present invention.

[0038] In the figure: 1-pole piece; 11-current collector; 111-second side; 12-pole ear; 121-welding area; 1211-welding point; 122-flexible part; 123-positive electrode ear; 124-negative electrode ear; 13-ear glue; 131-first side; 14-positive electrode sheet; 15-negative electrode sheet; 2-battery cell; 21-diaphragm; 3-insulating film. DETAILED DESCRIPTION

[0039] To make the technical solutions and advantages of the present invention more clear, the present invention and its beneficial effects will be described in further detail below in conjunction with specific implementation methods and accompanying drawings, but the implementation methods of the present invention are not limited thereto.

[0040] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] Example 1

[0042] like Figure 2 As shown, a button battery electrode comprises:

[0043] Current collector 11;

[0044] The pole tab 12 is provided with a pole tab glue 13, and one end of the pole tab 12 has a welding area 121, and the pole tab 12 is welded to the current collector 11 through the welding area 121;

[0045] At least a portion of the tab glue 13 overlaps with the current collector 11 , and a bendable flexible portion 122 is formed between the welding area 121 and the tab glue 13 .

[0046] Furthermore, the welding of the pole ear 12 and the current collector 11 can be performed by laser welding or ultrasonic welding, and ultrasonic welding is preferably used to more accurately control the size of the welding point 1211. The pole ear glue 13 can partially overlap with the current collector 11 or completely overlap with the current collector 11. It is only necessary to ensure that the subsequent pole ear glue 13 can be extended to the sealing part of the aluminum-plastic film to play an insulating role; preferably, the pole ear glue 13 partially overlaps with the current collector 11. The pole ear glue 13 can be set to a conventional square shape, or its shape can be changed according to the actual needs of button batteries or special-shaped batteries, such as round, oval, etc. The materials used for the current collector 11, the pole ear 12 and the pole ear glue 13 are changed according to the different positive and negative electrodes. For example, the pole ear material can be aluminum, copper, nickel, etc., and the thickness can be set to 0.05-0.2 mm.

[0047] Further, the tab glue 13 has a first side 131, which is a side facing the tab glue 13 and the welding area 121; the current collector 11 has a second side 111, which is a long side close to the lead-out end of the tab 12; the distance between the first side 131 and the second side 111 is greater than or equal to 0.5 mm, and is less than the width of the current collector 11. Preferably, the distance between the first side 131 and the second side 111 is 0.5-5 mm; more preferably, the distance between the first side 131 and the second side 111 is 1 mm. Setting the width of the overlapping area between the tab glue 13 and the current collector 11 to at least 0.5 mm can ensure that the tab 12 has enough bending area, so that there is enough distance between its lead-out point and the aluminum-plastic film, and further avoid the situation where the aluminum-plastic film is squeezed due to the bending sharp corner at the top. Moreover, the inventors have conducted repeated experiments on a large number of button batteries of different shapes, models and capacities and found that when the distance between the first side 131 and the second side 111 is 1 mm, that is, the length of the overlapping area between the ear glue 13 and the current collector 11 is 1 mm, the performance of the button battery is even better, indicating that at this distance, not only can the aluminum-plastic film be prevented from being squeezed, but it can also help increase the battery energy density.

[0048] Furthermore, if Figure 2As shown, the welding area 121 is formed with an array of welding points 1211, the diameter of the welding points 1211 is 0.01 to 0.5 mm, and the spacing between two adjacent welding points 1211 is 0.01 to 1 mm. Among them, the welding area 121 can be formed into a square, a circle or other shapes as a whole, and can be designed according to actual needs. By reducing the diameter of the welding points 1211 to less than 0.5 mm, and reducing the spacing between the welding points 1211, while ensuring sufficient contact between the pole ear 12 and the current collector 11, it can also prevent the welding head from falling off due to long-term use of the button battery, and effectively improve the reliability of the connection between the pole ear 12 and the current collector 11. Compared with conventional batteries, under the same welding area, the welding points 1211 of the present invention are closer, the overall surface area is larger, and the contact area with the current collector 11 is also larger, which is similar to the "skin effect" of the wire, and the current concentrated on the surface is also increased, so that the conductivity of the battery is also more excellent. In addition, welding of small solder joints is more effective in heat dissipation, which helps delay the temperature rise of the battery during rate discharge and ensures stable battery performance.

[0049] Example 2

[0050] like Figures 3 to 5 As shown, a button battery comprises a battery cell 2 formed by winding the pole piece 1 described in Example 1 and an aluminum-plastic film wrapped around the battery cell 2, wherein the aluminum-plastic film comprises a first aluminum-plastic film sheet and a second aluminum-plastic film sheet, and the pole ear 12 is horizontally bent through a flexible portion 122 and extends outward along the joint of the first aluminum-plastic film sheet and the second aluminum-plastic film sheet. The shape of the first aluminum-plastic film sheet and the second aluminum-plastic film sheet of the aluminum-plastic film can be adapted and modified according to the shape of the button battery, such as round or square, but the first aluminum-plastic film sheet and the second aluminum-plastic film sheet should be matched to meet the requirements of subsequent packaging of the battery cell.

[0051] Preferably, the distance between the outwardly extending pole ear 12 and the top of the first aluminum-plastic film is a, and the distance between the outwardly extending pole ear 12 and the bottom of the second aluminum-plastic film is b, a:b=(1~20):(20~1). The depth of the first aluminum-plastic film and the second aluminum-plastic film can be determined according to the distance ratio of a and b. Preferably, the depth of the second aluminum-plastic film can be designed to be greater than the depth of the first aluminum-plastic film, so that the ratio of a to b is 1:(4~8). Specifically, the distance a between the outwardly extending pole ear 12 and the top of the first aluminum-plastic film can be 1mm, and the distance b between the outwardly extending pole ear 12 and the bottom of the second aluminum-plastic film can be 4.4mm. More preferably, the depth of the second aluminum-plastic film can be designed to be slightly greater than the depth of the first aluminum-plastic film, so that the outwardly extending pole ear is drawn out from the middle area of ​​the aluminum-plastic film.

[0052] Preferably, the outer ring of the battery cell 2 is also covered with an insulating film 3, and the insulating film 3 covers the welding area 121, and the width of the insulating film 3 is approximately equal to the height of the welding area 121. After the winding of the battery cell 2 is completed, the insulating film 3 is pasted on the surface of its outer ring to fix the battery cell. At the same time, the insulating film 3 of the present invention also has a positioning function. The insulating film 3 is placed close to the flexible part 122 and wound around the welding area 121. The joint positioning effect of the welding area 121 and the insulating film 3 can help the flexible part 122 to be bent better, and the positioning function is mainly achieved by controlling the width of the insulating film 3. Specifically, the insulating film 3 can be covered with green glue, and the width of the green glue is preferably 2 to 7 mm.

[0053] Preferably, the electrode sheet 1 includes a positive electrode sheet 14 and a negative electrode sheet 15, and the electrode tab 12 includes a positive electrode tab 123 and a negative electrode tab 124. The positive electrode tab 123 is electrically connected to the positive electrode sheet 14, and the negative electrode tab 124 is electrically connected to the negative electrode sheet 15. The angle between the positive electrode tab 123 and the negative electrode tab 124 relative to the line connecting the winding center is 0 to 180°. The length of the negative electrode sheet 15 at the outermost circle of the battery cell 2 is different from that of the positive electrode sheet 14. Among them, the battery cell 2 is formed by sequentially arranging and winding the positive electrode sheet 14, the separator 21, and the negative electrode sheet 15. After the wrapping of the aluminum-plastic film is completed, the electrode tab 12 on the side of the aluminum-plastic film can be trimmed first, and then the electrode tab 12 can be folded back after cutting to a suitable length. According to the different lengths of the positive and negative electrode sheet collectors at the outermost circle of the battery cell 2, the electrode tab 12 can be output from both ends or from one end after being folded back. See. Figure 3 and Figure 5 The angle between the positive electrode ear 123 and the negative electrode ear 124 relative to the connecting line of the winding center can be selected as an appropriate angle according to actual production requirements; after folding back the electrode ear 12, the design of the button battery can be completed.

[0054] Example 3

[0055] This embodiment provides a method for preparing a button battery, comprising the following steps:

[0056] S1, welding the electrode tab 12 to the current collector 11 through the welding area 121;

[0057] S2, attaching the pole ear glue 13 to the pole ear 12 and close to the welding area 121, so that at least a part of the pole ear glue 13 overlaps with the current collector 11, and a flexible portion 122 is reserved between the welding area 121 and the pole ear glue 13;

[0058] S3, performing pit punching treatment on the first aluminum-plastic film and the second aluminum-plastic film respectively;

[0059] S4, placing the battery cell 2 in the pit of the second aluminum-plastic film, and then covering the first aluminum-plastic film along the direction of the second aluminum-plastic film, so that the tab is horizontally bent by the flexible portion 122 and extends outward along the covering portion of the first aluminum-plastic film and the second aluminum-plastic film, completing the packaging of the aluminum-plastic film;

[0060] S5. After the packaging is completed, the tab 12 is folded back to complete the preparation of the button battery.

[0061] Specifically, after the first aluminum-plastic film and the second aluminum-plastic film are punched, the battery cell 2 is placed in the second aluminum-plastic film pit, and the electrolyte is injected while the first aluminum-plastic film is used to cover and package the battery cell 2. Then, the battery cell 2 is formed and evacuated, and then the tabs are trimmed according to the actual battery size requirements to prevent the tabs from being too long and not conducive to subsequent packaging. After the trimming is completed, the tabs are folded back, and the folding direction and shape of the tabs can also be set according to the actual requirements of the battery; that is, the preparation of the button battery is completed.

[0062] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. A button battery electrode, characterized in that: include: Current collector(11); A pole lug (12) is provided with a pole lug glue (13); one end of the pole lug (12) has a welding area (121); the pole lug (12) is welded to the current collector (11) via the welding area (121); Wherein, at least a portion of the tab glue (13) overlaps with the current collector (11), and a bendable flexible portion (122) is formed between the welding area (121) and the tab glue (13).

2. The electrode sheet for button battery according to claim 1, characterized in that: The tab glue (13) has a first side edge (131), and the first side edge (131) is a side edge of the tab glue (13) that is arranged facing the welding area (121); The current collector (11) has a second side (111), and the second side (111) is a long side close to the lead-out end of the electrode tab (12); The distance between the first side edge (131) and the second side edge (111) is greater than or equal to 0.5 mm and less than the width of the current collector (11).

3. The electrode sheet for button battery according to claim 2, characterized in that: The distance between the first side edge (131) and the second side edge (111) is 0.5 to 5 mm.

4. The electrode sheet for button battery according to claim 1, characterized in that: The welding area (121) forms an array of welding points (1211), the diameter of the welding points (1211) is 0.01 to 0.5 mm, and the distance between two adjacent welding points (1211) is 0.01 to 1 mm.

5. A button battery, characterized in that: It comprises a battery core (2) formed by winding the pole piece (1) according to any one of claims 1 to 4 and an aluminum-plastic film wrapped around the battery core (2), wherein the aluminum-plastic film comprises a first aluminum-plastic film sheet and a second aluminum-plastic film sheet, and the pole ear (12) is horizontally bent through the flexible portion (122) and extends outward along the joint of the first aluminum-plastic film sheet and the second aluminum-plastic film sheet.

6. The button battery according to claim 5, characterized in that: The distance between the outwardly extending pole ear (12) and the top end of the first aluminum-plastic film is a, and the distance between the outwardly extending pole ear (12) and the bottom end of the second aluminum-plastic film is b, and a:b=(1-20):(20-1).

7. The button battery according to claim 5, characterized in that: The outer ring of the battery core (2) is also covered with an insulating film (3), and the insulating film (3) covers the welding area (121).

8. The button battery according to claim 5, characterized in that: The electrode sheet (1) comprises a positive electrode sheet (14) and a negative electrode sheet (15); the electrode tab (12) comprises a positive electrode tab (123) and a negative electrode tab (124); the positive electrode tab (123) is electrically connected to the positive electrode sheet (14); the negative electrode tab (124) is electrically connected to the negative electrode sheet (15); and the angle between the positive electrode tab (123) and the negative electrode tab (124) relative to the line connecting the winding center is 0 to 180°.

9. The button battery according to claim 8, characterized in that: The lengths of the negative electrode sheet (15) and the positive electrode sheet (14) at the outermost circle of the battery cell (2) are different.

10. A method for preparing a button battery according to claim 5, characterized in that: The following steps are involved: Welding the electrode tab (12) to the current collector (11) through the welding area (121); The tab glue (13) is attached to the tab (12) and close to the welding area (121), so that at least a portion of the tab glue (13) overlaps with the current collector (11), and a flexible portion (122) is reserved between the welding area (121) and the tab glue (13); Performing pit punching treatment on the first aluminum-plastic film and the second aluminum-plastic film respectively; The battery cell (2) is placed in the concave portion of the second aluminum-plastic film, and the first aluminum-plastic film is then covered along the direction of the second aluminum-plastic film, so that the tab (12) is horizontally bent from the flexible portion (122) and extends outward along the covering portion of the first aluminum-plastic film and the second aluminum-plastic film, thereby completing the packaging of the aluminum-plastic film; After the packaging is completed, the tab (12) is folded back to complete the preparation of the button battery.

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