Button cell, manufacturing method for gasket assembly, and assembling method for button cell

Abstract

A button cell (1) and an assembling method therefor, and a manufacturing method for a gasket (20). The button cell (1) comprises: a positive electrode cover assembly (220), comprising a positive electrode cover (11) and a gasket (20); a positive electrode current collector (14); and a positive electrode sheet (15), wherein the gasket (20) comprises a gasket portion (21) and an elastic piece portion (22) which are arranged crosswise; either or both of the elastic piece portion (22) and the gasket portion (21) is / are provided with protruding structure(s) (23); and the protruding structure(s) (23) pass(es) through a through hole (142) of the positive electrode current collector (14) and is / are fixed to the positive electrode sheet (15).

Description

Preparation method of button cell and gasket assembly and assembly method of button cell

[0001] The present application claims priority to Chinese Patent Application No. 202410832430.3, 202421470730.3, 202410832392.1, 202421470638.7, filed on June 25, 2024, with the Chinese Patent Office, the contents of which are incorporated herein by reference in their entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, in particular to a button cell, a preparation method of a gasket assembly, and an assembly method of a button cell. BACKGROUND

[0003] As a source of energy, stable power supply is a basic requirement for button cells. Since high internal resistance of button cells will cause short battery endurance time, capacity reduction, accelerated self-discharge speed, voltage reduction, and battery heating, the battery internal resistance is usually used as an important indicator to evaluate the reliability and stability of button cells, that is, the initial internal resistance of button cells is required to be lower than 10Ω, and the battery internal resistance is required to be lower than 20Ω after storage at 85℃ for one week.

[0004] With the development of society and changes in the market, the application environment of button cells is becoming more and more severe. For example, button cells are required to provide stable power supply under high temperature, high humidity, high pressure, high frequency vibration, and high speed centrifugation, that is, the battery internal resistance is required to be lower than 15Ω after storage at 125℃ for 100h. SUMMARY

[0005] With the increase of storage temperature of button cells from 85℃ to 125℃, the positive electrode current collector structure and the assembly process between the positive electrode cover and the positive electrode cover in the related technology increase the degree of bulging of the positive electrode cover, increase the gap between the positive electrode current collector and the positive electrode cover, and further cause poor contact between the positive electrode current collector and the positive electrode cover, and the current collection effect of the positive electrode current collector decreases, thereby causing the battery to be unable to provide stable power supply, and thus unable to meet the requirements of the current application scenarios of button cells.

[0006] In a first aspect, embodiments of the present application provide a button cell, comprising:

[0007] A positive electrode cover assembly includes a positive electrode cover and a gasket, and the gasket is installed inside the positive electrode cover.

[0008] A positive electrode current collector is arranged inside the positive electrode cover and is provided with a receiving cavity, and a through hole is arranged on the bottom wall of the positive electrode current collector.

[0009] A positive electrode sheet is located in the receiving cavity.

[0010] The gasket comprises a gasket part and a spring part arranged in cross, the length of the gasket part is L1, the length of the spring part is L2, L1>L2, any one or both of the gasket part and the spring part is provided with a protruding structure, the protruding structure penetrates the through hole and is fixed to the positive plate.

[0011] In a second aspect, the embodiments of the present application provide a preparation method of the gasket of the button cell, the preparation method comprises:

[0012] a plurality of connected spring parts in a strip shape are prepared by a stamping forming process;

[0013] a plurality of connected gasket parts in a strip shape are prepared by a stamping forming process;

[0014] After the spring part combination and the gasket part combination are adjusted to have their centers coincide, the spring part combination and the gasket part combination are welded together by a laser welding device to form a plurality of connected gaskets.

[0015] In a third aspect, the embodiments of the present application provide an assembly method of the button cell, the assembly method of the button cell comprises:

[0016] After the relative position degree between the gasket assembly and the positive cover is adjusted, the gasket and the positive cover are welded together to form a positive cover assembly;

[0017] The positive plate is placed into the positive current collector to form a positive assembly;

[0018] The negative plate is placed into the negative cover to form a negative cover assembly;

[0019] The separator and the positive current collector assembly are sequentially placed into the negative cover assembly to form an assembly;

[0020] The electrolyte is injected into the assembly;

[0021] The positive cover assembly is covered on the end of the assembly. Advantages

[0022] The button cell provided by the present application increases the gasket in the button cell, the gasket is connected to the positive cover, the length of the gasket part of the gasket is greater than the length of the spring part, and the two ends of the gasket part are connected to the positive current collector, any one or both of the spring part and the gasket part is further provided with a protruding structure, the protruding structure is used for further fixing the positive plate, so that the positive cover keeps in contact with the positive plate inside the positive current collector when the positive cover is swollen, thereby improving the stability of the internal structure of the battery.

[0023] The preparation method of the gasket provided by the application comprises the following steps: respectively combining a plurality of connected elastic pieces in a strip shape and a plurality of connected gaskets in a strip shape, adjusting the two to be in the center coincidence, and welding the elastic piece combination and the gasket combination together to form a plurality of connected gaskets by welding, so that the production efficiency of the gasket and the cost of the assembly process can be effectively improved.

[0024] The assembly method of the button cell provided by the application comprises the following steps: welding the gasket on the positive electrode cover, and using the protruding structure on the gasket to further fix the positive electrode piece, so that the positive electrode cover and the positive electrode piece inside the positive electrode current collector are kept in contact when the positive electrode cover is swollen, thereby improving the stability of the internal structure of the battery. BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a perspective view of a button cell according to an embodiment of the application;

[0026] FIG. 2 is another perspective view of a button cell according to an embodiment of the application;

[0027] FIG. 3 is a perspective view of a button cell according to another embodiment of the application;

[0028] FIG. 4 is a perspective view of a gasket according to an embodiment of the application;

[0029] FIG. 5a is a strip view of a gasket assembly according to an embodiment of the application;

[0030] FIG. 5b is a strip view of a gasket assembly according to another embodiment of the application;

[0031] FIG. 6 is a perspective view of an elastic piece according to an embodiment of the application;

[0032] FIG. 7a is a partial enlarged view of FIG. 6 according to an embodiment of the application;

[0033] FIG. 7b is a partial enlarged view of FIG. 6 according to another embodiment of the application;

[0034] FIG. 8 is another perspective view of a gasket according to an embodiment of the application;

[0035] FIG. 9a is a perspective view of a gasket according to a second embodiment of the application;

[0036] FIG. 9b is a perspective view of a gasket according to a third embodiment of the application;

[0037] FIG. 9c is a perspective view of a gasket according to a fourth embodiment of the application;

[0038] FIG. 9d is a perspective view of a gasket according to a fifth embodiment of the application;

[0039] Fig. 10 is a perspective view of the gasket after welding with the positive electrode cover according to an embodiment of the present application;

[0040] Fig. 11 is a cross-sectional view of the gasket after welding with the positive electrode cover according to an embodiment of the present application;

[0041] Fig. 12 is a front view of the gasket after welding with the positive electrode cover according to an embodiment of the present application;

[0042] Fig. 13 is a view of the welding point position of the gasket after welding with the positive electrode cover according to an embodiment of the present application;

[0043] Fig. 14 is a view of the gasket and the positive current collector at one angle according to an embodiment of the present application;

[0044] Fig. 15a is a view of the construction line of the gasket according to an embodiment of the present application;

[0045] Fig. 15b is a view of the construction line of the gasket according to another embodiment of the present application;

[0046] Fig. 16 is a view of the gasket and the positive current collector at another angle according to an embodiment of the present application;

[0047] Fig. 17 is a cross-sectional view of the gasket and the positive current collector according to an embodiment of the present application;

[0048] Fig. 18a is a view of the gasket and the positive current collector according to a comparative example of the present application;

[0049] Fig. 18b is a view of the gasket and the positive current collector according to another comparative example of the present application;

[0050] Fig. 19 is a view of the dimensions of the gasket according to an embodiment of the present application;

[0051] Fig. 20a is a cross-sectional view of the gasket according to Example 1 of the present application;

[0052] Fig. 20b is a cross-sectional view of the gasket according to Comparative Example 1 of the present application;

[0053] Fig. 20c is a cross-sectional view of the gasket according to Comparative Example 2 of the present application;

[0054] Fig. 21 is a cross-sectional view of a button cell according to an embodiment of the present application;

[0055] Fig. 22 is a cross-sectional view of a button cell according to another embodiment of the present application;

[0056] Fig. 23 is a cross-sectional view of a button cell according to another embodiment of the present application;

[0057] FIG. 24 is a cross-sectional view of another perspective of the button cell according to another embodiment of the present application;

[0058] FIG. 25 is a perspective view of the gasket according to an embodiment of the present application;

[0059] FIG. 26a is a perspective view of one corner of the gasket portion according to an embodiment of the present application;

[0060] FIG. 26b is a perspective view of another corner of the gasket portion according to an embodiment of the present application;

[0061] FIG. 26c is a perspective view of still another corner of the gasket portion according to an embodiment of the present application;

[0062] FIG. 27a is a perspective view of one corner of the spring portion according to an embodiment of the present application;

[0063] FIG. 27b is a perspective view of another corner of the spring portion according to an embodiment of the present application;

[0064] FIG. 27c is a cross-sectional view of still another corner of the spring portion according to an embodiment of the present application;

[0065] FIG. 27d is a perspective view of the spring portion according to another embodiment of the present application;

[0066] FIG. 28 is a schematic view of the welding area of the spring portion and the gasket portion according to an embodiment of the present application;

[0067] FIG. 29a is a partial enlarged view of the first structure of FIG. 27c;

[0068] FIG. 29b is a partial enlarged view of the second structure of FIG. 27c;

[0069] FIG. 29c is a partial enlarged view of the third structure of FIG. 27c;

[0070] FIG. 30 is a partial cross-sectional view of the button cell according to an embodiment of the present application;

[0071] FIG. 30a is a partial cross-sectional view of the button cell according to a comparative example of the present application;

[0072] FIG. 30b is a partial cross-sectional view of the button cell according to another comparative example of the present application;

[0073] FIG. 31 is a schematic view of the welding area of the gasket and the positive cap according to an embodiment of the present application;

[0074] FIG. 32a is a perspective view of the gasket according to another embodiment of the present application;

[0075] FIG. 32b is a perspective view of the gasket according to still another embodiment of the present application;

[0076] FIG. 33 is a cross-sectional view of a gasket welded to a positive cap according to an embodiment of the present application;

[0077] FIG. 34 is a perspective view of a gasket welded to a positive cap according to an embodiment of the present application;

[0078] FIG. 35 is a view of a position requirement of a second welding point of a gasket and a positive cap according to an embodiment of the present application;

[0079] FIG. 36a is a cross-sectional view of a button cell when a positive cap is bulged according to an embodiment of the present application;

[0080] FIG. 36b is a cross-sectional view of a button cell when a positive cap is bulged according to an embodiment of the present application;

[0081] FIG. 37 is a view of a position structure of a gasket and a positive current collector according to an embodiment of the present application;

[0082] FIG. 38 is a view of a position structure of a gasket and a positive current collector according to an embodiment of the present application;

[0083] FIG. 39 is a view of a position structure of a gasket and a positive current collector according to an embodiment of the present application;

[0084] FIG. 40 is a view of a position structure of a gasket and a positive current collector according to an embodiment of the present application;

[0085] FIG. 41 is a view of a construction line of a gasket according to an embodiment of the present application;

[0086] FIG. 42a is a view of a position structure of a gasket and a positive current collector according to an embodiment of the present application;

[0087] FIG. 42b is a view of a position structure of a gasket and a positive current collector according to a comparative example of the present application;

[0088] FIG. 42c is a view of a position structure of a gasket and a positive current collector according to another comparative example of the present application;

[0089] FIG. 43a is a view of a raw material structure of a gasket assembly according to an embodiment of the present application;

[0090] FIG. 43b is a view of a raw material structure of a spring assembly according to an embodiment of the present application;

[0091] FIG. 43c is a view of a raw material structure of a gasket assembly according to an embodiment of the present application;

[0092] FIG. 44a is a view of a partial structure of a spring part according to Embodiment 1 of the present application;

[0093] Fig. 44b is a schematic diagram of a partial structure of a spring sheet part provided by Comparative Example 1 of the present application;

[0094] Fig. 44c is a schematic diagram of a partial structure of a spring sheet part provided by Comparative Example 2 of the present application;

[0095] Reference signs:

[0096] 1, button cell; 11, positive cover; 111, boss structure; 12, negative cover; 13, sealing ring; 14, positive current collector; 141, annular bottom wall; 142, through hole; 143, side wall; 144, accommodation cavity; 15, positive sheet; 16, negative sheet; 17, separator; 19, electrolyte; 20, gasket; 21, gasket part; 211, gasket base body; 212, gasket boss; 213, gasket accommodation cavity; 214, gasket end part; 2141, first gasket end part; 2142, second gasket end part; 2143, gasket end point; 215, gasket side edge; 22, spring sheet part; 221, spring sheet base body; 222, spring sheet end part; 2221, first spring sheet end part; 2222, second spring sheet end part; 2223, spring sheet end point; 223, spring sheet boss; 224, spring sheet accommodation cavity; 23, protrusion structure; 231, first flange; 232, second flange; 233, protrusion; 23a, exceeding area; 23b, non-exceeding area; 24, base surface; 25, positioning hole; 200, gasket assembly; 210, first welding point; 241, second welding point; 242, third welding point; 220, positive cover assembly; Q1, first area; Q2a, first part of second area; Q2b, second part of second area; Q3a, first part of third area; Q3b, second part of third area; Q4, area where annular bottom wall is located; Q5, circular welding area; 100, positive assembly; 200, gasket assembly; 500, negative assembly; 300, spring sheet assembly; 400, gasket assembly; Embodiment of the present application

[0097] Example one

[0098] In the present application, the orientation words such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the direction of the drawing surface in the drawing, unless otherwise stated. "Inner" and "outer" refer to the outline of the device.

[0099] The button cell mainly consists of a positive cover, a negative cover, a sealing ring, a positive current collector, a positive sheet, a negative active material, a separator, and an electrolyte. In the related art, considering the cost of battery assembly process, the positive sheet is placed inside the positive current collector, then the positive current collector is placed inside the positive cover, and the positive cover and the positive current collector are tightly contacted by sealing and pressing.

[0100] Since the positive current collector is directly placed inside the positive cover, there is no positioning structure between the positive current collector and the positive cover, which causes the positive current collector to move easily inside the button cell, especially under severe vibration and high-speed centrifugation, the positive current collector is severely deviated, thereby causing poor contact of internal parts, so that the button cell is prone to current fluctuation, low voltage, low capacity and high resistance. When the button cell is stored at high temperature, the positive cover is swollen, a gap is formed between the positive current collector and the positive cover, thereby causing poor contact of internal parts, so that the button cell has low voltage, poor discharge and high internal resistance.

[0101] As an energy source, stable power supply is the basic requirement of button cell. Since high internal resistance of button cell will cause short battery life, low capacity, fast self-discharge speed, low voltage and battery heating, the battery internal resistance is usually used as one of the important indicators to evaluate the reliability and stability of button cell, that is, the initial internal resistance of button cell is required to be lower than 10Ω, and the battery internal resistance is required to be lower than 20Ω after storage at 85℃ for one week.

[0102] With the development of society and the change of market, the application environment of button cell is becoming more and more severe, such as requiring button cell to supply power stably under high temperature, high humidity and high pressure, high frequency vibration and high speed centrifugation, that is, the battery internal resistance is required to be lower than 15Ω after storage at 125℃ for 100h.

[0103] However, with the increase of storage temperature of button cell from 85℃ to 125℃, the positive current collector structure and the assembly process between the positive current collector and the positive cover in the related art cause the swelling degree of the positive cover to increase, the gap between the positive current collector and the positive cover to increase, and further cause the poor contact between the positive current collector and the positive cover and the current collection effect of the positive current collector to decrease, thereby causing the battery internal resistance to increase sharply and failing to meet the requirements of the current application scenarios of button cell.

[0104] In order to improve the stability of the electrical performance of button cell in extreme environment, the internal structure of button cell is optimized to improve the current collection effect.

[0105] Referring to FIGS. 1-3, the present application provides a button cell 1, which comprises a positive cover 11, a negative cover 12, a sealing ring 13, a positive current collector 14, a positive plate 15, a negative plate 16, a separator 17 and an electrolyte 19.

[0106] The positive cover 11 is provided as an open cover structure. As shown in FIG. 3, the outer side of the positive cover 11 can be configured as a vertical surface structure, and as shown in FIG. 1, the outer side of the positive cover 11 can also be provided with a boss structure.

[0107] The negative cover 12 is configured as an open cover structure. The inner diameter and the outer diameter of the positive cover 11 are greater than the inner diameter and the outer diameter of the negative cover 12, so that the positive cover 11 can be covered on the outside of the negative cover 12.

[0108] The sealing ring 13 is arranged at the connection between the positive cover 11 and the negative cover 12. The sealing ring 13 is configured as a wrapping structure for at least part of the wall of the negative cover 12, so that a sealed connection structure is formed between the positive cover 11 and the negative cover 12. At the same time, the sealing ring 13 also serves to provide insulation between the positive cover 11 and the negative cover 12.

[0109] The positive current collector 14 is accommodated in the inner cavity of the positive cover 11. The positive current collector 14 can be configured as any one of a current collecting ring, a current collecting net and a current collecting sheet. As shown in FIG. 1, the positive current collector 14 is configured as a current collecting ring, which includes an annular bottom wall 141 and a side wall 143 connected to the annular bottom wall 141 in a circumferential direction. The annular bottom wall 141 and the side wall 143 form a receiving cavity 144. The annular bottom wall 141 is provided with a through hole 142. The inner diameter of the positive current collector 14 is smaller than the inner diameter of the negative cover 12.

[0110] The positive sheet 15 is accommodated in the receiving cavity 144 of the positive current collector 14 and is in contact with the positive cover 11 through the through hole 142.

[0111] The negative sheet 16 is accommodated in the inner cavity of the negative cover 12.

[0112] The separator 17 is arranged between the positive sheet 15 and the negative sheet 16, and is used to separate the positive sheet 15 and the negative sheet 16. The projection of the negative sheet 16 on the separator 17 and the projection of the positive sheet 15 on the separator 17 can substantially coincide.

[0113] The electrolyte 19 is filled in the entire inside of the button cell 1. After the electrolyte is injected, the internal structures such as the positive sheet and the negative sheet are in a state of being soaked in the electrolyte. The charged ions in the positive sheet and the negative sheet are in current communication through the electrolyte.

[0114] With reference to FIGS. 1 to 3, the button cell 1 further includes a gasket 20, wherein the gasket 20 is connected to the inner surface of the positive cover 11. The gasket 20 includes a gasket portion 21 and a spring portion 22 arranged in a cross manner. The length L1 of the gasket portion 21 is greater than the length L2 of the spring portion 22. The two ends of the gasket portion 21 are connected to the positive current collector 14. The spring portion 22 is located inside the positive current collector 14. Any one or both of the spring portion 22 and the gasket portion 21 is provided with a protruding structure 23, which is used to fix the positive sheet 15.

[0115] By adding the gasket 20 in the button cell 1, the gasket 20 is connected to the positive cover 11, the length of the gasket part 21 of the gasket 20 is greater than the length of the spring part 22, the two ends of the gasket part 21 are connected to the positive current collector 14, the spring part 22 is located inside the positive current collector 14, and any one or both of the spring part 22 and the gasket part 21 are further provided with a protruding structure 23 for further fixing the positive sheet 15. The gasket 20 is arranged to be connected with the positive cover 11 and the positive current collector 14 respectively, and the protruding structure 23 on the gasket 20 is used to further fix the positive sheet 15, so that when the positive cover 11 is swollen, the positive cover 11 keeps in contact with the positive sheet 15 inside the positive current collector 14, thereby improving the stability of the internal structure of the battery.

[0116] With reference to FIGS. 4 and 6, the gasket part 21 and the spring part 22 of the gasket 20 and the protruding structure 23 are integrally formed, and the thickness of the gasket 20 is t, 0.05 mm≤t≤0.30 mm.

[0117] The material for making the gasket 20 can be one of SUS44, SUS304, SUS430, SUS316, and SUS444. In a specific embodiment, the gasket 20 is made of SUS430, so that the gasket 20 itself has magnetism, which is beneficial to reduce the welding difficulty of the gasket 20 with the positive cover 11 or the positive current collector 14 and improve the feasibility of welding.

[0118] The thickness of the gasket is 0.05 mm~0.30 mm, and in some embodiments, the thickness of the gasket 20 is 0.10 mm~0.20 mm. In a specific embodiment, the thickness of the gasket 20 can be 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, or a value between any two of the above values or a range between any two of the above values. The inventors have found through research that when the thickness t of the gasket 20 is <0.05 mm, the gasket 20 has low strength and is easy to deform, and cannot play the role of elastic connection of the gasket 20; when the thickness of the gasket 20 is >0.30 mm, the volume of the gasket 20 increases, which occupies the internal space of the battery, resulting in a decrease in the capacity of the battery.

[0119] As shown in FIGS. 5a and 5b, the application also provides a method for making a gasket, which is processed by a stamping forming process. In the stamping process, a plurality of gaskets 20 are wound into a plurality of gasket assemblies 200 in the form of a continuous material edge. With reference to FIG. 5a, the plurality of gaskets 20 are connected by a continuous material edge, and the single gasket 20 formed by cutting the adjacent two gaskets 20 still includes a protruding end structure at the side edge thereof. With reference to FIG. 5b, the plurality of gaskets 20 are directly connected, and the side edges of the single gasket 20 formed by cutting the adjacent two gaskets 20 are flush.

[0120] Continuing to refer to FIG. 4, the protruding structure 23 arranged on the gasket 20 for fixing the positive electrode tab 15 includes a first flange 231 and a second flange 232, wherein the first flange 231 and the second flange 232 are respectively located at two ends of the spring portion 22.

[0121] By arranging the first flange 231 and the second flange 232 at two ends of the spring portion 22 respectively, the first flange 231 and the second flange 232 can be embedded in the positive electrode tab 15, and compared with arranging the protruding structure 23 at other positions of the spring portion 22, arranging the protruding structure 23 at two ends of the spring portion 22 can increase the contact area between the gasket 20 and the positive electrode tab 15, and further improve the limiting effect of the protruding structure 23 on the positive electrode tab 15. Especially when the button cell 1 is in extreme vibration and centrifugation, the first flange 231 and the second flange 232 can effectively reduce the positional movement of the positive current collector 14 and the gasket 20 inside the battery, reduce the mutual impact force between the positive electrode tab 15, the negative electrode tab 16 and the electrolyte, further reduce the internal resistance of the battery, and improve the stability of the battery performance.

[0122] As shown in FIG. 6, the height of the first flange 231 or the second flange 232 is set as h1,2*t≤h1≤10*t; the angle formed by the extension line of the outer side surface of the first flange 231 or the second flange 232 and the plane where the spring portion 22 is located is 90°~150°.

[0123] In some embodiments, the first flange 231 and the second flange 232 are symmetrically arranged about the center of the gasket 20, the height of the first flange 231 protruding relative to the base surface 24 of the tab portion 22 is the same as the height of the second flange 232 protruding relative to the base surface 24 of the tab portion 22, and both are set to h1. In some examples, h1 can be 2t, 3t, 4t, 5t, 6t, 7t, 8t, 9t, 10t, a value between any two of the above values, or a range between any two of the above values. The inventors have found through research that when the height h1 of the first flange 231 or the second flange 232 satisfies 2*t≤h1≤10*t, the overall structure of the positive electrode tab 15 will not be damaged by the first flange 231 or the second flange 232 to cause tab corrosion or powder loss after the first flange 231 and the second flange 232 are embedded in the positive electrode tab 15, and the first flange 231 and the second flange 232 will not deform during embedding in the positive electrode tab 15. Specifically, when the height h1 of the first flange 231 or the second flange 232 is less than 2t, the first flange 231 or the second flange 232 does not embed deeply enough into the positive electrode tab 15, and when the positive electrode cover 11 bulges outward, the first flange 231 or the second flange 232 is easily separated from the positive electrode tab 15, resulting in poor contact between the gasket 20 and the positive electrode current collector 14 as a whole. When the height h1 of the first flange 231 or the second flange 232 is greater than 10t, the first flange 231 and the second flange 232 need to be embedded in the positive electrode tab 15 at a relatively deep depth, so that the gasket 20 is easily deformed and the overall structure of the positive electrode tab 15 is easily damaged during embedding of the first flange 231 and the second flange 232 in the positive electrode tab 15.

[0124] Continuing to refer to FIG. 6, the angle formed by the extension line of the outer side surface of the first flange 231 or the second flange 232 and the plane in which the tab portion 22 is located is θ1, and θ1 needs to satisfy 90°≤θ1≤150°.

[0125] In a specific implementation, the first flange 231 or the second flange 232 is symmetrically arranged about the center of the gasket 20, and the angle formed by the extension line of the outer side surface of the first flange 231 and the plane on which the spring sheet portion 22 is located is the same as the angle formed by the extension line of the outer side surface of the second flange 232 and the plane on which the spring sheet portion 22 is located, and both are set to θ1, which needs to satisfy 90°≤θ1≤150°. For example, θ1 can be 90°, 100°, 110°, 120°, 130°, 140°, 150°, an angle between any two of the above angles, or a range between any two of the above angles. The inventors have found through research that when θ1<90°, the first flange 231 or the second flange 232 is difficult to be embedded in the positive electrode sheet 15, and when θ1>150°, the first flange 231 or the second flange 232 is embedded in a range that is too large corresponding to the positive electrode sheet 15, which is easy to damage the overall structure of the positive electrode sheet 15, resulting in its powder falling off.

[0126] The first flange 231 or the second flange 232 can be provided in a straight edge inclined structure. As shown in FIG. 7a, the first flange 231 or the second flange 232 can also be provided in a wave-shaped inclined structure. As shown in FIG. 7b, the first flange 231 or the second flange 232 can also be provided in an inclined structure with a sharp corner structure at the end.

[0127] With continued reference to FIGS. 4 and 8, the protruding structure 23 includes at least two protrusions 233 arranged on the gasket portion 21, and the at least two protrusions 233 are symmetrically arranged on both sides of the spring sheet portion 22, respectively.

[0128] By arranging the at least two protrusions 233 on the gasket portion 21, the two protrusions 233 can further be embedded in the positive electrode sheet 15, thereby increasing the contact area between the gasket 20 and the positive electrode sheet 15, and thereby increasing the limiting effect of the protruding structure 23 on the positive electrode sheet 15, so that when the button cell 1 is in an extreme vibration or centrifugal situation, the protruding structure 23 can effectively prevent the relative displacement of the positive current collector 14 and the gasket 20 inside the button cell 1, thereby reducing the mutual impact force between the positive electrode sheet 15, the negative electrode sheet 16 and the electrolyte, reducing the internal resistance of the button cell 1, and thereby improving the stability of the electrical performance of the button cell 1.

[0129] Two protrusions 233 are arranged on the gasket portion 21, and the two protrusions 233 are symmetrically arranged with respect to the elastic sheet portion 22. A first flange 231 and a second flange 232 are respectively arranged at two ends of the elastic sheet portion 22, and the first flange 231 and the second flange 232 are symmetrically arranged with respect to the gasket portion 21. Due to the cross arrangement of the gasket portion 21 and the elastic sheet portion 22, the two protrusions 233 are configured to provide the positive plate 15 with a first direction fixing force, and the first flange 231 and the second flange 232 are configured to provide the positive plate 15 with a second direction fixing force. The positive plate 15 is simultaneously subjected to the first direction fixing force and the second direction fixing force provided by the gasket 20, so that the gasket 20 can sufficiently limit the displacement of the positive plate 15 relative to the gasket 20 in an extreme environment.

[0130] As shown in FIG. 8, the height of the protrusion 233 is h2, and 1.5*t≤h2≤3*t.

[0131] In a specific implementation, the height h2 of the protrusion 233 protruding relative to the plane on which the gasket portion 21 is arranged can be set to 1.5t, 2.0t, 2.5t, 3.0t, a value between any two of the above values, or a range between any two of the above values. The inventors have found through research that when the height h2 of the protrusion 233 is less than 1.5t, the two protrusions 233 do not embed into the positive plate 15 deeply enough, and when the positive cover 11 is externally bulged, the two protrusions 233 are easily separated from the positive plate 15, resulting in poor contact between the gasket 20 and the positive current collector 14 as a whole. When the height h2 of the two protrusions 233 is greater than 3*t, the two protrusions 233 need to be embedded into the positive plate 15 at a relatively deep depth, making the process of embedding the two protrusions 233 into the positive plate 15 more difficult, and the overall structure of the positive plate 15 is easily damaged, resulting in powder falling.

[0132] The overall shape of the two protrusions 233 can be set to a triangular pyramid shape or a multi-prism shape with sharp corners.

[0133] With continued reference to FIGS. 4, 9a-9d, the orthogonal projection of the gasket 20 on the positive cover 11 is set to a cross shape, a hoshi shape, or a combination of a circular shape and a cross shape.

[0134] The base surface 24 of the gasket 20 can be set to a cross shape. The gasket portion 21 and the elastic sheet portion 22 form a cross portion through the cross arrangement. The gasket portion 21 includes a first gasket portion 21 and a second gasket portion 21 symmetrically arranged with respect to the cross portion. The elastic sheet portion 22 includes a first elastic sheet portion 22 and a second elastic sheet portion 22 symmetrically arranged with respect to the cross portion.

[0135] In some examples, as shown in FIG. 4, the base surface 24 of the gasket 20 is provided in a regular cross structure, in which the two portions of the gasket portion 21 and the two portions of the spring portion 22 are provided in regular rectangular structures. In alternative examples, the base surface 24 of the gasket 20 can be provided in an irregular cross structure, as shown in FIG. 9a, in which the two portions of the gasket portion 21 are provided in circular arc edge structures, or as shown in FIG. 9b, in which the two portions of the gasket portion 21 are provided in fan structures, and the two portions of the spring portion 22 are also provided in fan structures, or as shown in FIG. 9c, in which the base surface 24 of the gasket 20 includes an outer ring portion and an inscribed portion, the outer ring portion is configured in a closed circular ring structure, and the inscribed portion is provided in a cross structure, and the two ends of the gasket portion 21 are connected to the ring-shaped edge. With reference to FIG. 9d, the base surface 24 of the gasket 20 is provided in a rice-shaped structure or other polygonal structures, and a plurality of extension portions are provided on the outer side of the intersection, i.e., a third extension portion, a fourth extension portion or a fifth extension portion is provided between the gasket portion 21 and the spring portion 22, in which the length of the gasket portion 21 is greater than the length of the spring portion 22, the length of the third extension portion and the length of the fourth extension portion.

[0136] With reference to FIGS. 10-12, the gasket 20 is provided with a positioning hole 25 for positioning when the gasket 20 is welded to the positive electrode cover 11. The gasket 20 is welded to the inner surface of the positive electrode cover 11, and the concentricity of the gasket 20 and the positive electrode cover 11 is less than or equal to 0.3 mm.

[0137] The gasket 20 is welded to the inner surface of the positive electrode cover 11, and the gasket 20 is provided with a positioning hole 25 at the center position of the gasket 20, and the intersection area of the gasket portion 21 and the spring portion 22 is located at the center position of the gasket 20, and the positioning hole 25 is located at the center of the intersection area of the gasket portion 21 and the spring portion 22.

[0138] The roll-shaped gasket assembly 200 shown in FIGS. 5a and 5b is cut into individual gaskets 20 in a laser welding device, and the positive electrode cover 11 is placed in a jig using a vibratory bowl feeder. During the welding of the gasket 20 and the positive electrode cover 11, the positioning hole 25 of the gasket 20 is clamped by the jig to position the gasket 20 on the inner surface of the positive electrode cover 11 through the positioning hole 25, and the gasket 20 and the positive electrode cover 11 are welded together by laser welding.

[0139] During the assembling process, the concentricity between the gasket 20 and the positive cover 11 needs to be controlled to be ≤0.3mm, and in some embodiments, the concentricity between the gasket 20 and the positive cover 11 is ≤0.1mm. The inventor has found through research that if the concentricity between the positive cover 11 and the gasket 20 is >0.3mm, it will cause the gasket 20 to be severely offset from the positive cover 11, and in turn cause the gasket 20 to be severely offset from the positive current collector 14, and in turn cause the current collection effect of the positive current collector 14 to decrease, further affecting the electrical performance of the button cell 1.

[0140] As shown in FIG. 13, the first welding points 210 formed by welding between the gasket 20 and the positive cover 11 are at least two, and the at least two first welding points 210 are symmetrically arranged about the center of the gasket 20.

[0141] The inventor has found through research that during the welding process between the gasket 20 and the positive cover 11, the number of first welding points 210 formed by welding between the gasket 20 and the positive cover 11 is set to two, and the two first welding points 210 help to improve the welding strength between the gasket 20 and the positive cover 11. If the number of first welding points 210 formed by welding between the gasket 20 and the positive cover 11 is one, it will cause the gasket 20 to be easily offset and warped relative to the positive cover 11, and if the number of first welding points 210 formed by welding between the gasket 20 and the positive cover 11 is greater than two, it will cause the welding process between the gasket 20 and the positive cover 11 to be complicated, and at the same time will increase the welding cost.

[0142] With continued reference to FIG. 13, by optimizing the position of the welding area between the gasket 20 and the positive cover 11, the stability performance of the button cell 1 can be further improved.

[0143] The base surface 24 of the gasket 20 available for welding is divided into five regions, i.e., a first region Q1, a second region first part Q2a, a second region second part Q2b, a third region first part Q3a, and a third region second part Q3b. The first region Q1 is located at the intersection region of the gasket portion 21 and the spring portion 22, the second region first part Q2a and the second region second part Q2b are arranged on both sides of the first region Q1 and on the gasket portion 21, and the third region first part Q3a and the third region second part Q3b are arranged on both sides of the first region Q1 and on the spring portion 22. The length of the gasket portion 21 is L1, and the length d1 of the first region Q1 extending along the gasket portion 21 satisfies d1=0.5L1, and the width of the first region Q1 extending along the spring portion 22 is equal to the width of the gasket portion 21.

[0144] The first welding point 210 between the gasket 20 and the positive cover 11 can be arranged on the first area Q1 or on the second area first part Q2a and the second area second part Q2b. In some embodiments, the first welding point 210 between the gasket 20 and the positive cover 11 is arranged on the second area first part Q2a and the second area second part Q2b, and the first welding point 210 between the gasket 20 and the positive cover 11 is arranged outside the third area first part Q3a and the third area second part Q3b. The inventor has found through research that if the first welding point 210 between the gasket 20 and the positive cover 11 is arranged on the third area first part Q3a and the third area second part Q3b, the third area first part Q3a and the third area second part Q3b where the gasket 20 is arranged will lose elasticity, and when the positive cover 11 bulges, the first flange 231 and the second flange 232 on the gasket 20 will be welded on the positive cover 11, thereby causing the first flange 231 and the second flange 232 to separate from the positive plate 15, and further causing the gasket 20 to fail to contact the positive plate 15, so that the first flange 231 and the second flange 232 fail to limit the positive plate 15.

[0145] The application also provides an assembling method of the button cell, which comprises:

[0146] The positive cover 11 and the gasket 20 are welded to form a positive cover assembly 220;

[0147] The positive plate 15 is pressed into the inner cavity of the positive current collector 14 to form a sleeved positive plate;

[0148] The negative plate is placed in the inner cavity of the negative cover 12, and the separator 17, the sleeved positive plate are sequentially placed, the sealing ring 13 is wrapped on the outer surface of the negative cover 12, the electrolyte is injected, and then the positive cover assembly 220 is covered to seal the button cell 1, and the button cell 1 is pre-discharged and aged after the assembly is completed.

[0149] The gasket 20 is welded on the inner surface of the positive cover 11, and the positive current collector 14 is placed on the gasket 20, and the positions of the positive current collector 14 and the gasket 20 are not completely concentric, that is, there is a position deviation between the center of the positive current collector 14 and the center of the gasket 20.

[0150] As shown in FIGS. 14-17, the positive current collector 14 comprises an annular bottom wall 141, and the annular bottom wall 141 is provided with a through hole 142, and the two ends of the gasket part 21 are connected with the annular bottom wall 141.

[0151] As shown in FIG. 15a, FIG. 15b, FIG. 16 and FIG. 17, the diameter of the circumscribed circle corresponding to the edge of the gasket portion 21 is set as D1, the diameter of the circumscribed circle corresponding to the edge of the spring portion 22 is set as D2, the diameter of the through hole 142 of the positive current collector 14 is set as D3, the diameter of the annular bottom wall 141 of the positive current collector 14 is set as D4, the thickness of the positive current collector 14 is set as t1, the gasket portion 21 includes two end portions, one of which is located on a side edge including two end points, and the included angle between the two end points and the center line of the gasket 20 is set as 2θ2.

[0152] With reference to FIG. 15a, in one embodiment, the gasket portion 21 includes two gasket side edges 215, each of which is provided with a protruding gasket end portion 214, wherein the side edge where the gasket end portion 214 is located includes two gasket end points 2143, and the included angle between the two gasket end points 2143 and the center line of the gasket 20 is set as 2θ2.

[0153] With reference to FIG. 15b, in another embodiment, the gasket portion 21 includes two gasket side edges 215, which are set as straight edges, and the gasket end portion 214 is formed by the gasket side edge 215, and the gasket end portion 214 includes two gasket end points, and the included angle between the two gasket end points and the center line of the gasket 20 is set as 2θ2.

[0154] In order to ensure that the two ends of the gasket portion 21 of the gasket 20 are always in contact with the annular bottom wall 141 of the positive current collector 14, i.e., the two ends of the gasket portion 21 are always located in the area Q3 where the annular bottom wall 141 of the positive current collector 14 is located, and the two ends of the gasket portion 21 still overlap the area Q3 where the annular bottom wall 141 of the positive current collector 14 is located after the battery is sealed, the inventors have found through research that the length L1 of the gasket portion 21 satisfies: L1=D1*cosθ2, 1.02*D3≤L1 / cosθ2≤0.98*(D4-2t1), i.e., 1.02*D3*cosθ2≤L1≤0.98*(D4-2t1)*cosθ2.

[0155] Continuing to refer to FIG. 18a, if the length of the gasket portion 21 is set as Lla, Lla>0.98*(D4-2t1)*cosθ2, at least a part of the area where one flange of the gasket 20 is located exceeds the edge of the positive current collector 14, as the exceeding area 23a shown in FIG. 18a, and the area where the other flange of the gasket 20 is located does not exceed the edge of the positive current collector 14, as the non-exceeding area 23b shown in FIG. 18a, during the sealing process of the button cell 1, because the strength of the edge of the positive current collector 14 is greater than the strength of the plane where the bottom wall of the positive current collector 14 is located, the height corresponding to the exceeding area 23a of the gasket 20 exceeding the edge of the positive current collector 14 is greater than the height corresponding to the non-exceeding area 23b of the gasket 20 not exceeding the edge of the positive current collector 14, and a height difference occurs inside the positive current collector 14, which leads to the deterioration of the current collecting effect of the positive current collector 14.

[0156] Continuing to refer to FIG. 18b, if the length of the gasket portion 21 is set as Llb, Llb<1.02*D3*cosθ2, the area where one flange of the gasket 20 is located is located in the area where the through hole 142 of the positive current collector 14 is located, as the exceeding area 23a shown in FIG. 18b, and the other flange of the gasket 20 is located in the plane area where the bottom wall of the positive current collector 14 is located, as the non-exceeding area 23b shown in FIG. 18b, during the sealing process of the button cell 1, the height corresponding to the exceeding area 23a of the one flange of the gasket 20 located in the through hole 142 of the positive current collector 14 is greater than the height corresponding to the non-exceeding area 23b of the other flange of the gasket 20 located in the plane of the bottom wall of the positive current collector 14, and a height difference occurs inside the positive current collector 14, which leads to the deterioration of the current collecting effect of the positive current collector 14.

[0157] Continuing to refer to FIGS. 15a, 15b, 17 and 19, the length of the gasket portion 21 is set as Ll, the length of the spring portion 22 is set as L2, the width of the gasket portion 21 extending along the extension direction of the spring portion 22 is set as w3, the spring portion 22 includes two spring end portions 222, each spring end portion 222 includes two spring end points 2223, the included angle between the two spring end points 2223 and the center of the gasket 20 is set as 2*θ3, and the diameter of the through hole 142 of the positive current collector 14 is set as D3.

[0158] The first flange 231 and the second flange 232 of the gasket 20 are provided in an inclined structure with a certain inclination angle, and the first flange 231 and the second flange 232 are embedded in the positive plate 15 to limit the positive plate 15 when the button cell 1 is packaged. In order to ensure that there is a positional deviation between the gasket 20 and the positive current collector 14 or the positive cover 11 expands outward, the first flange 231 and the second flange 232 of the gasket 20 can still be embedded in the positive plate 15 and elastically connected between the positive plate 15. The inventor found through research that the length of the elastic sheet part 22 is L2, and L2 satisfies: 1.5*w3≤L2≤0.98*D3*cosθ3.

[0159] If the length L2 of the elastic sheet part 22 is greater than 0.98*D3*cosθ3, the relative positional deviation between the gasket 20 and the positive current collector 14 is large, which causes any one or both of the first flange 231 and the second flange 232 to be unable to be embedded in the positive plate 15; if the length L2 of the elastic sheet part 22 is less than 1.5*w3, when the positive cover 11 expands outward, any one or both of the first flange 231 and the second flange 232 of the gasket 20 will move outward with the positive cover 11, thereby causing any one or both of the first flange 231 and the second flange 232 to be separated from the positive plate 15. The gasket 20 loses the elastic limiting effect on the positive current collector 14, and poor contact occurs between the gasket 20 and the positive current collector 14.

[0160] In the present application, a specific embodiment 1 and comparative examples 1 and 2 are further provided. The button cell 1 provided by the embodiment 1 and the comparative examples 1 and 2 is subjected to a high-temperature storage experiment to further verify the change of the internal resistance of the battery in the high-temperature environment of the embodiment 1, the comparative example 1 and the comparative example 2.

[0161] Embodiment 1

[0162] The button cell 1 provided by the embodiment 1 includes the gasket 20. The cross-sectional structure of the gasket 20 is shown in FIG. 20a. The base surface 24 of the gasket 20 adopts a central cross circularly symmetric structure, the length L1=0.91*(D4-2t1)*cosθ2, L2=0.72*D3*cosθ3, t=0.10, θ1=120°, and H1=4*t.

[0163] Comparative Example 1

[0164] The button cell provided by the comparative example 1 includes the gasket 20. The cross-sectional structure of the gasket 20 is shown in FIG. 20b. The base surface 24 of the gasket 20 adopts a central cross circularly symmetric structure, the length L1=0.91*(D4-2t1)*cosθ2, L2=0.72*D3*cosθ3, t=0.10, θ1=120°, and H1=10*t.

[0165] Comparative Example 2

[0166] The coin cell provided by Comparative Example 2 includes the gasket 20, the cross-sectional structure of which is shown in FIG. 20c, and the base surface 24 of the gasket 20 adopts a central cross circumferential symmetrical structure, with L1=0.91*(D4-2t1)*cosθ2, L2=0.72*D3*cosθ3, t=0.10, θ3=120°, and H1=2*t.

[0167] (High-temperature storage test: internal resistance evaluation) The coin cells of Example 1, Comparative Example 1, and Comparative Example 2 obtained in the above order were subjected to the high-temperature storage test described below, whereby the change in internal resistance in a high-temperature environment was evaluated.

[0168] Specifically, first, the internal resistance (Ω) between the positive electrode and the negative electrode of the coin cells of Example 1, Comparative Example 1, and Comparative Example 2 was measured in the same manner, and was indicated as the initial resistance (Ω) in Table 1 below. Next, the coin cells of Example 1, Comparative Example 1, and Comparative Example 2 were stored in a high-temperature chamber, the internal temperature of which was set to 125°C, for one week, and after the storage for one week, the internal resistance (Ω) between the positive electrode and the negative electrode of the coin cells of Example 1, Comparative Example 1, and Comparative Example 2 was measured in the same manner, and was indicated as the internal resistance (Ω) after storage for one week in Table 1 below.

[0169] Table 1

[0170]

[0171] Evaluation results:

[0172] As shown in Table 1, the initial internal resistance of the coin cell of Example 1 (flange height of 4t) was significantly superior to that of Comparative Example 1 (flange height of 10t). After disassembling and analyzing the coin cell, it was found that the initial internal resistance of Comparative Example 1 was much higher than that of Example 1, because after the flange of the gasket 20 was embedded in the positive electrode sheet 15, the flange of the gasket 20 was deformed and the positive electrode sheet 15 was powdery, which resulted in poor internal contact and thus a much higher initial internal resistance than that of Example 1.

[0173] Comparing Example 1 (flange height of 4t) with Comparative Example 2 (flange height of 2t), the initial internal resistance of the coin cell was not much different, but after the coin cell was stored at 125°C for one week, the internal resistance increase rate of the coin cell provided by Comparative Example 2 was much higher than that of the coin cell provided by Example 1. After taking an image of the coin cell CT, it was found that the flange part of the gasket 20 and the positive electrode sheet 15 of the coin cell provided by Comparative Example 2 were separated, which resulted in poor internal contact of the coin cell under high-temperature storage.

[0174] Example Two

[0175] In the related art, the button cell mainly consists of a positive cover, a negative cover, a sealing ring, a positive sheet, a negative sheet, a positive current collector, a separator and an electrolyte. Considering the manufacturing process and assembly cost, the positive current collector is usually provided in a sheet body, a mesh body or a ring body structure. In the battery assembly process, the positive sheet is assembled with the positive current collector to form a positive assembly, which is placed in the inner cavity of the battery and is packaged inside the battery by a mold.

[0176] Since the positive assembly is fixed in the inner cavity of the battery by the packaging pressure of the mold, this single fixing method makes the fixing reliability of the positive assembly in the battery low. Especially when the button cell is under the action of high-speed centrifugation and high-temperature conditions, the positive assembly is prone to serious shaking and deviation, which further causes serious separation between the positive assembly and the positive cover, collision between the positive sheet and the electrolyte, and other problems, thereby seriously affecting the stability of the battery performance and making the battery unable to meet the requirements of harsh application environments.

[0177] For example, when the battery is under a high-temperature condition of 150℃, the internal pressure of the battery increases due to the gas production of the electrolyte, which further causes the positive cover and the negative cover to deform and swell, thereby causing a gap between the positive cover and the positive sheet, and an increase in the internal resistance of the battery, which leads to unqualified battery performance. When the battery is under the action of a high-speed centrifugal force of 3300g, since the positive assembly is directly placed inside the positive cover, there is no fixing action and limiting action between the current collecting ring / positive current collector / current collecting sheet and the positive cover, which causes the positive assembly to easily move inside the battery and collide with the electrolyte, thereby causing the electrical performance stability of the button cell to decrease or even the button cell to fail.

[0178] As an energy source, the button cell is required to stably supply power at-40℃~85℃, which is its basic requirement. Since a high battery internal resistance will cause the button cell to have a shortened endurance time, a reduced battery capacity, an accelerated self-discharge speed, a reduced voltage and a self-heating problem of the battery, the battery internal resistance is one of the important indicators for evaluating the reliability and stability of the button cell, and the initial internal resistance of the button cell is usually required to be lower than 10Ω, and the internal resistance of the battery after being stored at 85℃ for one week is required to be lower than 20Ω.

[0179] With the development of society and the change of market, the application environment of the button cell is becoming more and more severe, for example, the button cell is required to stably supply power under high-temperature, high-humidity and high-pressure, high-frequency vibration and high-speed centrifugation conditions. It is found through testing that when the temperature of the application scene of the button cell is increased from 85℃ to 125℃, the positive cover in the button cell structure in the related art will swell seriously with the increase of temperature, the gap between the positive cover and the positive current collecting member will increase, thereby causing the current collecting effect of the positive current collecting member to decrease, thereby causing the internal resistance of the button cell to increase sharply, and thereby causing the button cell to be unable to meet the requirements of the current application scene.

[0180] With the increasing market demand for use under high-speed centrifugal conditions, it is required that the button cell can still work normally under the action of 3300g high-speed centrifugal force. However, in the related art, the positive assembly structure moves and is offset and has no elastic contact under the action of 3300g high-speed centrifugal force, which leads to the increase of the internal resistance of the button cell, and further leads to the instability of the electrical performance of the button cell, so that the button cell cannot meet the requirements of the current application scenarios.

[0181] In order to improve the stability of the electrical performance of the button cell in extreme application scenarios, the internal structure of the button cell is optimized in the present application.

[0182] Referring to FIGS. 21-24, the second embodiment of the present application provides a button cell 1, which comprises a positive cover 11, a negative cover 12, a sealing ring 13, a positive current collector 14, a positive sheet 15, a negative sheet 16, a separator 17 and an electrolyte.

[0183] The positive cover 11 is provided as an open cover-like body structure, as shown in FIGS. 21 and 22. The outer side of the positive cover 11 can be configured as a vertical surface structure, as shown in FIGS. 23 and 24. The outer side of the positive cover 11 can also be provided with a boss structure.

[0184] The negative cover 12 is provided as an open cover-like body structure. The inner diameter and the outer diameter of the positive cover 11 are both greater than the inner diameter and the outer diameter of the negative cover 12, so that the positive cover 11 can be covered on the outside of the negative cover 12.

[0185] The sealing ring 13 is arranged at the connection between the positive cover 11 and the negative cover 12. The sealing ring 13 is configured to wrap at least a part of the wall of the negative cover 12, so that a sealed connection structure is formed between the positive cover 11 and the negative cover 12. At the same time, the sealing ring 13 also serves to provide an insulation effect between the positive cover 11 and the negative cover 12.

[0186] The positive current collector 14 comprises an annular bottom wall 141 and a side wall 143 connected circumferentially to the annular bottom wall 141. The annular bottom wall 141 and the side wall 143 form a receiving cavity 144. The annular bottom wall 141 is provided with a through hole 142. The outer diameter of the positive current collector 14 is smaller than the inner diameter of the negative cover 12.

[0187] The positive sheet 15 is received in the inside of the receiving cavity 144 of the positive current collector 14 and is in contact with the positive cover 11 through the through hole 142. In the process of assembling the battery, the positive sheet 15 is placed into the inside of the positive current collector 14 to form a positive assembly 100.

[0188] The negative sheet 16 is received in the inner cavity of the negative cover 12. In the process of assembling the battery, the negative sheet 16 is placed into the inside of the negative cover 12 to form a negative assembly 500.

[0189] The diaphragm 17 is arranged between the positive electrode sheet 15 and the negative electrode sheet 16, and separates the positive electrode sheet 15 and the negative electrode sheet 16. The projected area of the negative electrode sheet 16 on the diaphragm 17 can substantially coincide with the projected area of the positive electrode sheet 15 on the diaphragm 17.

[0190] The electrolyte is filled in the inside of the button cell 1. After the electrolyte is injected, the internal structure such as the negative electrode sheet, the positive electrode sheet and the like is in a state of being soaked in the electrolyte. The charged ions in the positive electrode sheet and the negative electrode sheet are in current communication through the electrolyte.

[0191] Referring to FIG. 21, FIG. 22 and FIG. 25, the button cell 1 further comprises a gasket 20, which comprises a gasket portion 21 and a spring portion 22 connected with each other, wherein the gasket portion 21 and the spring portion 22 are arranged separately. The length of the gasket portion 21 is set as L1, and the length of the spring portion 22 is set as L2, L1>L2. The gasket portion 21 and the spring portion 22 are cross-connected, and the two ends of the gasket portion 21 are connected to the positive current collector. The gasket 20 further comprises a protruding structure 23, which penetrates through the through hole of the positive current collector and is fixed on the positive electrode sheet 15. The protruding structure 23 can be arranged on the gasket portion 21, or the protruding structure 23 can be arranged on the spring portion 22, or the protruding structure 23 is arranged on both the spring portion 22 and the gasket portion 21. In the button cell, the positive electrode sheet 15 is arranged as a compacted powder structure, and the protruding structure 23 can be directly embedded in the positive electrode sheet 15.

[0192] By adding the gasket 20 in the button cell 1, the gasket 20 is connected to the positive cover 11, and the gasket 20 comprises the gasket portion 21 and the spring portion 22 cross-connected with each other, wherein the length L1 of the gasket portion 21 is greater than the length L2 of the spring portion 22, and the two ends of the gasket portion 21 are connected to the positive current collector 14, and the spring portion 22 is located in the positive current collector 14. The protruding structure 23 arranged on any one or both of the gasket portion 21 and the spring portion 22 is further fixed in the positive electrode sheet 15. Therefore, when the positive cover 11 is externally drummed, the gasket 20 can further maintain the contact connection between the positive cover 11 and the positive electrode sheet 15 and the positive current collector 14, thereby improving the stability of the internal structure of the button cell 1.

[0193] Referring to FIG. 21, FIG. 25, FIG. 26a and FIG. 27a, the gasket portion 21 comprises a gasket base 211 and a gasket boss 212 protruding relative to the gasket base 211, the gasket boss 212 and the gasket base 211 define a gasket accommodating cavity 213, the gasket accommodating cavity 213 is configured to accommodate a portion of the spring portion 22, so that the spring portion 22 and the gasket portion 21 can form a stable connection structure. It can be understood that if the spring portion 22 is directly connected on the gasket base 211 of the gasket portion 21, the spring base 221 will protrude relative to the gasket base 211, when the gasket portion 21 is connected on the positive current collector 14, the spring portion 22 located inside the current collector 14 needs to be completely embedded in the positive plate 15, which greatly increases the assembly difficulty between the gasket 20 and the positive assembly 100. Therefore, the gasket boss 212 protruding relative to the gasket base 211 of the gasket portion 21 is arranged on the gasket portion 21, the gasket boss 212 and the gasket base 211 define the gasket accommodating cavity 213, the spring portion 22 is placed in the gasket accommodating cavity 213, so that the gasket base 211 and the spring base 221 can be located in the same plane, thereby greatly reducing the assembly difficulty between the gasket 20 and the positive assembly 100.

[0194] In other alternative examples, as shown in FIG. 27d, the spring portion 22 comprises a spring base 221 and a spring boss 223 protruding relative to the spring base 221, the spring boss 223 and the spring base define a spring accommodating cavity 224, the spring accommodating cavity 224 is configured to accommodate a portion of the gasket portion 21.

[0195] With reference to FIG. 26a, FIG. 26b, FIG. 26c, FIG. 27a, FIG. 27b and FIG. 27c, the thickness of the spring portion 22 is set as t1, the height of the gasket boss 212 is set as H1, H1≥t1; the width of the spring portion 22 is set as w1, the width of the gasket boss 212 is set as w2, w2=(1.05~1.3)*w1.

[0196] The inventor found through research that when the height H1 of the gasket boss 212 and the thickness t1 of the spring portion 22 satisfy H1≥t1, the spring portion 22 can be completely accommodated in the gasket accommodating cavity 213 defined by the gasket boss 212 along the thickness direction of the spring portion 22. If the height H1 of the gasket boss 212 and the thickness t1 of the spring portion 22 satisfy H1

[0197] The inventor found through research that when the width w2 of the gasket boss 212 and the width w1 of the spring piece 22 satisfy w2=(1.05~1.3)w1, the spring piece 22 can be completely accommodated in the gasket accommodation cavity 213 defined by the gasket boss 212 along the width direction of the spring piece 22, and a sufficient assembly allowance is formed between the spring piece 22 and the gasket boss 212. If the width w2 of the gasket boss 212 is less than 1.05w1, when the spring piece 22 and the gasket 21 are both made of hard material, a part of the spring piece 22 cannot be assembled into the gasket accommodation cavity 213 defined by the gasket boss 212. If the width w2 of the gasket boss 212 is greater than 1.3w1, the assembly gap between the spring piece 22 and the gasket boss 212 is too large, which causes waste of the internal space of the button cell 1.

[0198] Similarly, if a spring boss 223 is arranged on the spring piece 22, the spring boss 223 and the spring base body 221 define a spring accommodation cavity 224, and a part of the gasket 21 is accommodated in the spring accommodation cavity 224, correspondingly, the thickness of the gasket 21 is set to t2, the height of the spring boss 223 is not less than the thickness t2 of the gasket 21; the width of the gasket 21 is set to w3, and the ratio between the width of the spring boss 223 and the width of the gasket is in the range of (1.05~1.3).

[0199] If the height of the spring boss 223 and the thickness t2 of the gasket 21 do not satisfy the above size requirement, at least a part of the gasket 21 will protrude relative to the spring base body 221 of the spring piece 22 along the thickness direction of the gasket 21, which causes the gasket 20 to occupy more space inside the button cell 1.

[0200] If the size ratio between the height of the spring boss 223 and the width w3 of the gasket 21 is outside the range of 1.05~1.3, the gasket cannot be assembled into the spring accommodation cavity 224 defined by the spring boss 223, or the assembly gap between the gasket and the spring boss 223 is too large, which causes waste of the internal space of the button cell 1.

[0201] Continuing to refer to FIG. 27c, the thickness t1 of the spring sheet portion 22 satisfies: 0.05 mm≤t1≤0.30 mm. In specific implementations, the thickness t1 of the spring sheet portion 22 can be 0.05 mm, 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, a value between any two of the above values, or a range between any two of the above values. The inventors have found through research that when the thickness t1 of the spring sheet portion 22 is <0.05 mm, the overall strength of the spring sheet portion 22 is insufficient, which in turn causes the spring sheet portion 22 to be unable to stably embed into the positive electrode sheet. When the thickness t1 of the spring sheet portion 22 is >0.30 mm, the overall size of the spring sheet portion 22 is large, which in turn causes the gasket 20 to occupy a large amount of internal space of the button cell. The inventors have further found through research that in some implementations, the thickness t1 of the spring sheet portion 22 is set to 0.10 mm~0.20 mm, such that the spring sheet portion 22 can simultaneously satisfy optimization between its strength and size ratio.

[0202] Continuing to refer to FIG. 26c, the thickness t2 of the gasket portion 21 satisfies: 0.05 mm≤t2≤0.30 mm. In specific implementations, the thickness t2 of the gasket portion 21 can be 0.05 mm, 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, a value between any two of the above values, or a range between any two of the above values. The inventors have found through research that when the thickness t2 of the gasket portion 21 is <0.05 mm, the overall strength of the gasket portion 21 is insufficient, which in turn causes the gasket portion 21 to be unable to stably embed into the positive electrode sheet. When the thickness t2 of the gasket portion 21 is >0.30 mm, the overall size of the gasket portion 21 is large, which in turn causes the gasket assembly to occupy a large amount of internal space of the button cell. The inventors have further found through research that in some embodiments, the thickness t2 of the gasket portion 21 is set to 0.10 mm~0.20 mm, such that the gasket portion 21 can simultaneously satisfy optimization between its strength and size ratio.

[0203] The thickness t2 of the gasket portion 21 and the thickness t1 of the spring sheet portion 22 described above can be set to be different, as long as they are within the specified size range. The inventors have further found through research that in some embodiments, the thickness t2 of the gasket portion 21 and the thickness t1 of the spring sheet portion 22 are set to be the same, such that the gasket portion 21 and the spring sheet portion 22 connected to form the gasket 20 have the same strength at each location, which is conducive to providing stable connection between the gasket 20 and the positive electrode assembly and the positive electrode cover.

[0204] The material suitable for preparing the gasket portion 21 or the spring portion 22 includes a stainless steel material, and suitable stainless steel materials include at least one of SUS44, SUS304, SUS430, SUS316, and SUS444, wherein the gasket portion 21 and the spring portion 22 can be prepared by using different and performance-close stainless steel materials. In some embodiments, the gasket portion 21 and the spring portion 22 are both prepared by using SUS430, so that the gasket portion 21 and the spring portion 22 are both magnetic, facilitating the connection between the gasket portion 21 and the spring portion 22 by welding and reducing the welding difficulty therebetween and improving the stability of the welding. It can be understood that, if the gasket portion 21 and the spring portion 22 are prepared by using the same stainless steel material, it is beneficial to maintain no potential difference between the gasket portion 21 and the spring portion 22.

[0205] Referring to FIG. 28, the spring portion 22 is welded on the gasket portion 21 to form the gasket 20, and the number of the second welding points 241 between the spring portion 22 and the gasket portion 21 is even, for example, the number of the second welding points 241 can be two, four, six, or eight, and in some embodiments, the number of the second welding points 241 is set to two.

[0206] The inventor finds through research that, if the spring portion 22 and the gasket portion 21 are single-point welded or if the number of the second welding points 241 between the spring portion 22 and the gasket portion 21 is an odd number greater than 1, it will cause the problem of unstable welding between the spring portion 22 and the gasket portion 21 and further cause the problem of relative position deviation between the spring portion 22 and the gasket portion 21. If the spring portion 22 and the gasket portion 21 are three-point welded or four-point welded, it will further increase the cost of the welding process, which is not conducive to improving the production efficiency. Thus, in a specific embodiment, the number of the welding points between the spring portion 22 and the gasket portion 21 is set to two.

[0207] Continuing to refer to FIG. 28, the welding area formed between the spring portion 22 and the gasket portion 21 is set as a circular welding area Q5, the distance between the two second welding points 241 is set as the diameter of the circular welding area Q5, and the center of the circular welding area Q5 coincides with the center of the gasket 20. The diameter of the circular welding area Q5 is not greater than the width w1 of the spring portion 22, and the diameter of the circular welding area Q5 is less than the width w3 of the gasket portion 21.

[0208] The spring portion 22 and the gasket portion 21 form the circular welding area Q5, and the center of the circular welding area Q5 coincides with the center of the gasket 20, so that a stable welding is formed between the spring portion 22 and the gasket portion 21, and it is beneficial to form a center-symmetrical structure of the gasket 20.

[0209] The diameter of the circular welding area Q5 is set to be not greater than the width w1 of the spring sheet portion 22, and the diameter of the circular welding area Q5 is set to be not greater than the width w3 of the gasket portion 21, so that the circular welding area Q5 is located substantially in the central intersection area between the spring sheet portion 22 and the gasket portion 21, without causing the problem that the spring sheet portion 22 and the gasket portion 21 are not symmetrical about the center of the gasket 20 after being welded.

[0210] With continued reference to FIGS. 22, 25, 27a and 30, the protruding structure 23 includes a first flange 231 and a second flange 232 arranged on the spring sheet portion 22, where the first flange 231 is located at one end of the spring sheet portion 22, and the second flange 232 is located at the other end of the spring sheet portion 22.

[0211] The first flange 231 and the second flange 232 are respectively embedded in the positive electrode sheet 15, and thus the distance between the first flange 231 and the second flange 232 is configured to be the effective range of the positive electrode sheet 15 that can be limited by the gasket 20 as a whole. If the first flange 231 and the second flange 232 are located at the middle position of the spring sheet portion 22, the effective range of the positive electrode sheet 15 corresponding to the first flange 231 and the second flange 232 will be smaller, and thus the limiting effect of the gasket 20 on the positive electrode sheet 15 will be weakened.

[0212] With continued reference to FIG. 27c, the first flange 231 and the second flange 232 are symmetrically arranged about the center of the gasket 20, and the first flange 231 and the second flange 232 protrude from the spring sheet base 221 with the same height h1, which is configured to be h1. In some embodiments, the height h1 of the first flange 231 or the second flange 232 satisfies 2*t1≤h1≤10*t1 with respect to the thickness t1 of the spring sheet portion 22.

[0213] In some examples, h1 can be 2t1, 3t1, 4t1, 5t1, 6t1, 7t1, 8t1, 9t1, 10t1, a value between any two of the above values, or a range between any two of the above values.

[0214] The inventors have found through research that when the height h1 of the first flange 231 or the second flange 232 satisfies 2*t1≤h1≤10*t1, after the first flange 231 and the second flange 232 are embedded in the positive electrode sheet 15, the overall structure of the positive electrode sheet 15 will not be damaged by the first flange 231 or the second flange 232 to cause sheet decay or powder loss, and the first flange 231 and the second flange 232 will not be deformed during embedding in the positive electrode sheet 15.

[0215] Referring to FIG. 30a, if the height of the first flange 231 or the height of the second flange 232 is h1 < 2t, when the positive electrode cover 11 is externally drummed, the first flange 231 or the second flange 232 is easily separated from the positive electrode tab 15, resulting in poor contact of the gasket 20 as a whole with the positive electrode current collector 14, because the first flange 231 or the second flange 232 is not embedded in the positive electrode tab 15 to a sufficient depth.

[0216] Referring to FIG. 30b, if the height of the first flange 231 or the height of the second flange 232 is h1 > 10t1, the first flange 231 and the second flange 232 need to be embedded in the positive electrode tab 15 to a deep depth, so that the gasket 20 is easily deformed and the overall structure of the positive electrode tab 15 is easily damaged in the process of embedding the first flange 231 or the second flange 232 in the positive electrode tab 15.

[0217] Referring to FIG. 29a, the extension line of the outer side surface of the first flange 231 or the second flange 232 is arranged at the same angle θ1 with the plane in which the spring sheet base 221 is located, and θ1 satisfies 90° ≤ θ1 ≤ 150°.

[0218] In a specific implementation, the first flange 231 or the second flange 232 is symmetrically arranged about the center of the gasket 20, the angle formed by the extension line of the outer side surface of the first flange 231 with the plane in which the spring sheet base 221 is located is the same as the angle formed by the extension line of the outer side surface of the second flange 232 with the plane in which the spring sheet base 221 is located, and both are arranged at θ1, and θ1 needs to satisfy 90° ≤ θ1 ≤ 150°. For example, θ1 can be 90°, 100°, 110°, 120°, 130°, 140°, 150°, and an angle between any two of the above angles or a range between any two of the above angles.

[0219] The inventors have found through research that when θ1 < 90°, the first flange 231 or the second flange 232 is difficult to be embedded in the positive electrode tab 15, and when θ1 > 150°, the range corresponding to the embedding of the first flange 231 or the second flange 232 in the positive electrode tab 15 is too large, which easily damages the overall structure of the positive electrode tab 15, resulting in powder falling off.

[0220] Referring to FIG. 29a, the first flange 231 or the second flange 232 can be arranged in a straight edge inclined structure. Alternatively, as shown in FIG. 9b, the first flange 231 or the second flange 232 can also be arranged in a wave-shaped inclined structure. Alternatively, as shown in FIG. 9c, the first flange 231 or the second flange 232 can also be arranged in an inclined structure with a sharp corner structure at the end.

[0221] With reference to FIG. 21, FIG. 26a, the protruding structure 23 further comprises a gasket boss 212 arranged on the gasket portion 21, the gasket boss 212 penetrates through the through hole 142 and is embedded in the positive plate 15. The gasket boss 212 is located at the central position of the gasket base 211, the gasket boss 212 is arranged protrudingly relative to the plane where the gasket base 211 is located, and the gasket boss 212 defines a gasket accommodating cavity 213 for accommodating at least a part of the pellet portion 22. The gasket boss 212 can be embedded in the positive plate 15, thereby providing a fixing effect on the positive plate 15.

[0222] The gasket portion 21 and the pellet portion 22 are welded to form the gasket 20, the gasket boss 212 forms a reinforcing rib structure on the pellet portion 22, so that the gasket boss 212 has high strength after being embedded in the positive plate 15, and the gasket boss 212 and the pellet portion 22 combine to form a protruding structure with high embedding strength, so that the protruding structure can be in strong contact with the positive plate 15, thereby avoiding the problem that the positive cover 11 and the positive plate 15 are separated and thus the contact is poor when the positive cover 11 is bulged out.

[0223] Further, if the gasket portion 21 and the pellet portion 22 are arranged in an integrated structure, the strength of the gasket boss 212 is low, which is equivalent to that the gasket accommodating cavity 213 defined by the gasket boss 212 does not accommodate the pellet. Therefore, when the height H1 of the gasket boss 212 is high, the gasket boss 212 is prone to deformation when being embedded in the positive plate 15. When the height H1 of the gasket boss 212 is low, although the strength of the gasket boss 212 can be improved, the gasket boss 212 cannot be embedded in the positive plate 15 or the depth of the gasket boss 212 embedded in the positive plate 15 is not enough, thereby failing to provide an effective fixing effect.

[0224] With reference to FIG. 31, the orthographic projection of the gasket 20 on the positive cover 11 is arranged in a cross shape, and the orthographic projection of the gasket portion 21 and the pellet portion 22 on the positive cover 11 is arranged in a straight line shape. The gasket 20 and the positive cover 11 are arranged in a central symmetric structure, and the center of the gasket 20 is substantially coincident with the center of the positive cover 11.

[0225] By arranging the gasket 20 in a cross shape, and arranging the orthographic projection of the gasket portion 21 and the pellet portion 22 on the positive cover 11 in a straight line shape, it is beneficial for the two ends of the gasket portion 21 with a relatively long length in the gasket 20 to be connected with the positive current collector 14, and the pellet portion 22 with a relatively short length in the gasket 20 is located in the inside of the positive current collector 14.

[0226] The cross-shaped structure of the gasket 20 can be a regular cross-shaped structure as shown in FIG. 31. The cross-shaped structure of the gasket 20 can also be an irregular cross-shaped structure as shown in FIG. 32a, in which the two ends of the gasket portion 21 are provided in a circular arc structure. Alternatively, as shown in FIG. 32b, the gasket base body 211 includes two partial gasket base bodies 211 located on both sides of the gasket boss 212, and the two partial gasket base bodies 211 are provided in a fan-shaped structure.

[0227] Referring to FIGS. 31, 33 and 34, the gasket 20 is welded on the positive electrode cover 11, and the gasket 20 and the positive electrode cover 11 are both provided in a central symmetric structure, and the concentricity between the gasket 20 and the positive electrode cover 11 is not greater than 0.3 mm.

[0228] During the welding of the gasket 20 and the positive electrode cover 11, the concentricity between the gasket 20 and the positive electrode cover 11 needs to be controlled to be not greater than 0.3 mm. In some embodiments, the concentricity between the gasket 20 and the positive electrode cover 11 is not greater than 0.1 mm. The inventors have found through research that if the concentricity between the positive electrode cover 11 and the gasket 20 is greater than 0.3 mm, the gasket 20 and the positive electrode cover 11 will be severely misaligned, which will further cause the gasket 20 and the current collector 14 to be severely misaligned, which will further cause the current collection effect of the positive electrode current collector 14 to decrease, further affecting the electrical performance of the button cell 1.

[0229] With continued reference to FIG. 31, the number of third welding points 242 formed by welding between the gasket 20 and the positive electrode cover 11 is at least two, and the at least two third welding points 242 are symmetrically arranged about the center of the gasket 20.

[0230] The inventors have found through research that during the welding of the gasket 20 and the positive electrode cover 11, the number of third welding points 242 formed by welding between the gasket 20 and the positive electrode cover 11 is set to two, which helps to improve the welding strength between the gasket 20 and the positive electrode cover 11. If the number of third welding points 242 formed by welding between the gasket 20 and the positive electrode cover 11 is one, the gasket 20 will be prone to misalignment and edge lifting relative to the positive electrode cover 11. If the number of third welding points 242 formed by welding between the gasket 20 and the positive electrode cover 11 is greater than two, the welding process between the gasket 20 and the positive electrode cover 11 will be complicated, and the welding cost will also be increased.

[0231] With continued reference to FIGS. 31 and 35, by optimizing the position of the welding area between the gasket 20 and the positive electrode cover 11, the stability performance of the button cell 1 can be further improved.

[0232] The base of the gasket 20 available for welding is divided into five regions, i.e., a first region Q1, a second region first part Q2a, a second region second part Q2b, a third region first part Q3a, and a third region second part Q3b. The first region Q1 is set as the welding region of the gasket part 21 and the spring part 22. The second region first part Q2a and the second region second part Q2b are arranged on both sides of the first region Q1 and located on the gasket part 21. The third region first part Q3a and the third region second part Q3b are arranged on both sides of the first region Q1 and located on the spring part 22.

[0233] The third welding point 242 between the gasket 20 and the positive cover 11 is arranged on the second region first part Q2a and the second region second part Q2b. The third welding point 242 between the gasket 20 and the positive cover 11 is arranged outside the third region first part Q3a and the third region second part Q3b.

[0234] The inventor finds that if the third welding point 242 between the gasket 20 and the positive cover 11 is arranged on the third region first part Q3a and the third region second part Q3b, the third region first part Q3a and the third region second part Q3b where the gasket 20 is located will lose elasticity. When the positive cover 11 bulges, the first flange 231 and the second flange 232 on the gasket 20 are welded on the positive cover 11, which causes the first flange 231 and the second flange 232 to separate from the positive plate 15, and further causes the gasket 20 to be in poor contact with the positive plate 15, so that the first flange 231 and the second flange 232 lose the limiting effect on the positive plate 15. It should be noted that the first region Q1 cannot continue to be used as the welding region of the gasket 20 and the positive cover 11 because the first region Q1 is set as the welding region of the gasket part 21 and the spring part 22.

[0235] Continuing to refer to FIGS. 27b, 31 and 35, the distance between the at least two third welding points 242 is set as d1, which satisfies: 0.3*L1+0.7*w1≤d1≤0.9*L1+0.1*w1. Wherein, L1 is set as the length of the gasket part 21, and w1 is set as the width of the spring part 22.

[0236] The inventor found through research that, in order to ensure the consistency of the performance of the gasket 20 after it is welded to the positive cover 11, the third welding points 242 between the gasket 20 and the positive cover 11 are provided as two, and the two third welding points 242 are symmetrically distributed about the center of the gasket 20. Further, in order to ensure that the button cell is applied at high temperature, when the positive cover 11 bulges outward, the gasket 20 is connected to the positive assembly, and a non-contact gap is not generated between the gasket 20 and the positive cover 11, so it is required that the distance d1 between the two third welding points 242 satisfies: 0.3*L1+0.7*w1≤d1≤0.9*L1+0.1*w1, wherein as shown in FIGS. 35, 36a and 36b, L3=0.3*L1+0.7*w1, L4=0.9*L1+0.1*w1, L3≤d1≤L4, when the distance d1 between the two third welding points 242 is too large, i.e. d1 is greater than 0.9L1+0.1w1, the third welding points 242 are arranged at a position close to the edge of the gasket 20, the welding strength between the gasket 20 and the positive cover 11 is low, and when the positive cover 11 bulges outward, the gasket 20 is easily separated from the positive cover 11, thereby causing the connection between the gasket 20 and the positive cover 11 to fail. As shown in FIGS. 36a and 36b, when the distance d1 between the two third welding points 242 is too small, i.e. d1 is less than 0.3*L1+0.7*w1, the third welding points 242 are arranged at a position close to the center of the positive cover 11, and when the positive cover 11 bulges outward, the gasket 20 bulges outward with the positive cover 11, thereby causing the gasket 20 to be easily separated from the positive plate 15, the limiting effect of the gasket 20 on the positive plate 15 is lost, and thereby causing the problem of poor contact between the positive plate 15 and the positive cover 11.

[0237] Referring to FIGS. 35, 37 and 38, the positive current collector 14 includes an annular bottom wall 141 defining a through hole 142, and the two ends of the gasket portion 21 are connected to the annular bottom wall 141, so that the two ends of the gasket portion 21 are pressed between the annular bottom wall 141 and the positive cover 11, and the positive plate 15 accommodated inside the positive cover 11 contacts the positive cover 11 through the through hole 142.

[0238] Referring to FIGS. 37-41 and FIG. 42a, the diameter of the circumscribed circle corresponding to the edge of the gasket portion 21 is set as D1, the diameter of the circumscribed circle corresponding to the edge of the spring portion 22 is set as D2, the gasket portion 21 includes oppositely arranged first and second end portions 2141 and 2142, the first end portion 2141 includes two first end points 2143, the included angle between the line connecting the two first end points 2143 and the center of the gasket 20 is 2θ2, the diameter of the through hole 142 of the positive current collector 14 is set as D3, the outer diameter of the annular bottom wall 141 of the positive current collector 14 is set as D4, the thickness of the positive current collector 14 is set as t3, and the length L1 of the gasket portion 21 satisfies: L1=D1*cosθ2, and 1.02*D3*cosθ2≤L1≤0.98*(D4-2t3)*cosθ2.

[0239] In order to ensure that the two ends of the gasket portion 21 remain in contact with the annular bottom wall 141 of the positive current collector 14, and that the two ends of the gasket portion 21 still overlap the annular bottom wall 141 of the positive current collector 14 after the button cell 1 is sealed, the inventors have found through research that in some embodiments, 1.02*D3*cosθ2≤L1≤0.98*(D4-2t3)*cosθ2.

[0240] Further referring to FIG. 42b, if the length of the gasket portion 21 is set as L1a, L1a>0.98*(D4-2t3)*cosθ2, at least a part of the region where one end of the gasket portion 21 is located exceeds the region Q4 where the annular bottom wall 141 of the positive current collector 14 is located, as shown by the excess region 21a in FIG. 42b, and the other end of the gasket portion 21 does not contact the region Q4 where the annular bottom wall 141 is located, as shown by 41b in FIG. 42b. During the sealing process of the button cell 1, since the edge of the positive current collector 14 has a greater strength than the plane where the annular bottom wall 141 of the positive current collector 14 is located, the height corresponding to the excess region 21a of the gasket portion 21 that exceeds the edge of the positive current collector 14 is greater than the height corresponding to the non-excess region 21b of the gasket portion 21 that does not exceed the edge of the positive current collector 14, a height difference occurs inside the positive current collector 14, which leads to a poor current collecting effect of the positive current collector 14.

[0241] Further referring to Fig. 42c, if the length of the gasket portion 21 is set as L1b, L1b < 1.02 * D3 * cosθ2, one end of the gasket portion 21 is located in the area where the through hole 142 of the positive current collector 14 is located, i.e., the exceeding area 41c shown in Fig. 42c, and the other end of the gasket portion 21 is located in the planar area Q4 where the annular bottom wall 141 of the positive current collector 14 is located, i.e., the non-exceeding area 21d shown in Fig. 42c. During the sealing process of the button cell 1, the height corresponding to the exceeding area 21c where the through hole 142 of the positive current collector 14 is located is greater than the height corresponding to the non-exceeding area 21d where the annular bottom wall 141 of the positive current collector 14 is located, i.e., the other end of the gasket portion 21. As a result, a height difference occurs in the positive current collector 14, which leads to poor current collecting effect of the positive current collector 14.

[0242] Continuing to refer to Figs. 39 to 42, the spring portion 22 includes a first spring end 2221 and a second spring end 2222. The first spring end 2221 includes two spring end points 2223, and the included angle between the two spring end points 2223 and the line connecting the center of the gasket 20 is 2θ3. The length L2 of the spring portion 22 satisfies: 1.5 * w3 ≤ L2 ≤ 0.98 * D3 * cosθ3, where w3 is the width of the gasket portion 21, and D3 is the inner diameter of the through hole 142.

[0243] During the packaging of the button cell 1, the first flange 231 and the second flange 232 of the spring portion 22 are embedded in the positive sheet 15 to limit the positive sheet 15. In order to ensure that the first flange 231 and the second flange 232 of the spring portion 22 can still be embedded in the positive sheet 15 and elastically connected with the positive sheet 15 when there is a positional deviation between the gasket 20 and the positive current collector 14 or the positive cover 11 is outwardly bulged, the inventors have found through research that the length L2 of the spring portion 22 needs to satisfy: 1.5 * w3 ≤ L2 ≤ 0.98 * D3 * cosθ3.

[0244] If the length L2 of the spring portion 22 is greater than 0.98 * D3 * cosθ3, the relative positional deviation between the gasket 20 and the positive current collector 14 is large, which leads to that any one or both of the first flange 231 and the second flange 232 cannot be embedded in the positive sheet 15. If the length L2 of the spring portion 22 is less than 1.5 * w3, when the positive cover 11 is outwardly bulged, any one or both of the first flange 231 and the second flange 232 of the spring portion 22 will move outwardly with the positive cover 11, which leads to that any one or both of the first flange 231 and the second flange 232 is separated from the positive sheet 15. As a result, the gasket 20 loses the elastic limiting effect on the positive current collector 14, and poor contact occurs between the gasket 20 and the positive current collector 14.

[0245] The application also provides a preparation method of the gasket 20 for the button cell 1. Referring to FIGS. 43a, 43b and 43c, the preparation method of the gasket 20 comprises the following steps:

[0246] A plurality of connected gasket assemblies 400 in a strip shape are prepared by a stamping forming process, and adjacent gasket assemblies are connected by a connecting material edge, as shown in FIG. 43a.

[0247] A plurality of connected spring assemblies 300 in a strip shape are prepared by a stamping forming process, and adjacent spring assemblies are connected by a connecting material edge, as shown in FIG. 43b.

[0248] After the spring assembly 300 and the gasket assembly 400 are adjusted to have their centers coincide with each other, the spring assembly 300 and the gasket assembly 400 are welded together by a laser welding device to form a plurality of connected gasket components, and adjacent gasket components are connected by a connecting material edge, as shown in FIG. 43c.

[0249] Compared with the preparation method of welding a single gasket and a single spring to form the gasket 20 one by one, the above preparation method of the gasket 20 can effectively improve the production efficiency of the gasket 20 and the cost of the assembly process.

[0250] The embodiment of the application also provides an assembly method of a button cell, which comprises the following steps:

[0251] Step 1: a single gasket assembly is formed by cutting the connected gasket assembly;

[0252] Step 2: the relative position between the gasket assembly and the positive cover is adjusted, and then the gasket assembly and the positive cover are welded together to form a positive cover assembly, as shown in FIG. 44;

[0253] Step 3: a positive plate is placed in the positive current collector to form a positive assembly;

[0254] Step 4: a negative plate is placed in the negative cover to form a negative cover assembly;

[0255] Step 5: a separator and the positive assembly are sequentially placed in the negative cover assembly to form an assembly;

[0256] Step 6: electrolyte is injected into the assembly;

[0257] Step 7: the positive cover assembly, a seal, and a formation are arranged on the end of the assembly to form a button cell.

[0258] It should be noted that the order of the steps in the above preparation method can be adjusted according to the actual assembly process, and is not limited to the order described in the above embodiment.

[0259] In the present application, further provided is a specific embodiment 2, and comparative examples 3-6. The high-temperature storage experiment is performed on the button cell 1 provided by the embodiment 2 and the comparative examples 3-6, to further verify the change of the internal resistance of the battery in the high-temperature environment of the embodiment 2, the comparative example 3, the comparative example 4, the comparative example 5 and the comparative example 6.

[0260] Embodiment 2

[0261] Referring to FIG. 44a, the button cell provided by the embodiment 2 includes the gasket 20, and the structure of the gasket 20 is shown in FIG. 25, wherein the gasket base body and the spring base body both adopt a linear structure, the length L1 of the gasket satisfies L1=0.91*(D4-2t3)*cosθ2, the length L2 of the spring satisfies L2=0.72*D3*cosθ3, the thickness t2 of the gasket or the thickness t1 of the spring satisfies t1=t2=0.10, the angle θ1 of the first flange or the second flange satisfies θ1=120°, and the height h1 of the first flange or the second flange satisfies h1=4t1.

[0262] Comparative Example 3

[0263] Referring to FIG. 44c, the button cell provided by the comparative example 3 includes the gasket 20, and the structure of the gasket 20 is shown in FIG. 25, wherein the gasket base body and the spring base body both adopt a linear structure, the length L1 of the gasket satisfies L1=0.91*(D4-2t3)*cosθ2, the length L2 of the spring satisfies L2=0.72*D3*cosθ3, the thickness t2 of the gasket or the thickness t1 of the spring satisfies t1=t2=0.10, the angle θ1 of the first flange or the second flange satisfies θ1=120°, and the height h1 of the first flange or the second flange satisfies h1=10*t1.

[0264] Comparative Example 4

[0265] Referring to FIG. 44b, the button cell provided by the comparative example 4 includes the gasket 20, and the structure of the gasket 20 is shown in FIG. 25, wherein the gasket base body and the spring base body both adopt a linear structure, the length L1 of the gasket satisfies L1=0.91*(D4-2t1)*cosθ2, the length L2 of the spring satisfies L2=0.72*D3*cosθ3, the thickness t2 of the gasket or the thickness t1 of the spring satisfies t1=t2=0.10, the angle θ1 of the first flange or the second flange satisfies θ1=120°, and the height h1 of the first flange or the second flange satisfies h1=2t1.

[0266] Comparative Example 5

[0267] The coin cell provided by Comparative Example 5 includes the gasket 20, and the structure of the gasket 20 is shown in FIG. 25, wherein the gasket base and the spring base are both in a linear structure, the length L1 of the gasket is 0.90*D3*cosθ2, the length L2 of the spring is 0.72*D3*cosθ3, the thickness t2 of the gasket or the thickness t1 of the spring satisfies: t1=t2=0.10t, the angle θ1 of the first flange or the second flange satisfies: θ1=120°, and the height h1 of the second flange satisfies: h1=4t1.

[0268] Comparative Example 6

[0269] The coin cell provided by Comparative Example 6 includes the gasket 20, and the structure of the gasket 20 is shown in FIG. 25, wherein the gasket base and the spring base are both in a linear structure, the length L1 of the gasket is 0.90*D3*cosθ2, the length L2 of the spring is 0.72*D3*cosθ3, the thickness t2 of the gasket or the thickness t1 of the spring satisfies: t1=t2=0.10t, the angle θ1 of the first flange or the second flange satisfies: θ1=120°, and the height h1 of the second flange satisfies: h1=4t1.

[0270] High-temperature storage test (internal resistance evaluation):

[0271] The coin cells provided by Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6 obtained in the above order were subjected to the high-temperature storage test described below, whereby the change in internal resistance in a high-temperature environment was evaluated.

[0272] Specifically, first, the internal resistance (Ω) between the positive electrode and the negative electrode of the coin cells obtained in Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6 was measured in the same manner, respectively, as the initial resistance (Ω) and was indicated in Table 2 below. Next, the coin cells of Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6 were stored in a high-temperature chamber, the internal temperature of which was set to 125°C, for one week, and after the storage for one week, the internal resistance (Ω) between the positive electrode and the negative electrode of the coin cells of Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5 and Comparative Example 6 was measured in the same manner, respectively, as the internal resistance (Ω) after storage for one week and was indicated in Table 2 below.

[0273] Table 2

[0274]

[0275] Evaluation results:

[0276] As shown in Table 2, comparing Example 2 and Comparative Example 3, the height h1 of the first flange or the second flange of the gasket of the button cell of Example 2 is set to 4t1, and the initial internal resistance is 3.259 Ω. The height h1 of the first flange or the second flange of the gasket of the button cell of Comparative Example 3 is set to 10t1, and the initial internal resistance of the button cell of Example 2 is obviously better than that of Comparative Example 3. After disassembling and analyzing the battery, the initial internal resistance of the button cell of Comparative Example 3 is much higher than that of Example 2. The reason is that the first flange or the second flange of the button cell of Comparative Example 3 is deformed after embedding the positive plate, and the positive plate is powdery, which leads to poor internal contact, and thus the initial internal resistance of the button cell of Comparative Example 3 is much higher than that of Example 1.

[0277] As shown in Table 2, comparing Example 2 and Comparative Example 4, the height h1 of the first flange or the second flange of the gasket of the button cell of Example 2 is set to 4t1, and the height h1 of the first flange or the second flange of the gasket of the button cell of Comparative Example 4 is set to 2t1. The initial internal resistance of the button cell of Example 2 and that of Comparative Example 4 are not much different, but after 1 week of high-temperature storage at 125℃, the internal resistance increase rate of the button cell of Comparative Example 4 is much higher than that of Example 2. After CT (computed tomography) imaging analysis of the button cell, it is found that a part of the first flange or the second flange of the gasket assembly of the button cell of Comparative Example 4 is separated from the positive plate, which leads to poor internal contact of the button cell under high-temperature storage.

[0278] The results of the above-described examples and comparative examples show that by setting the height h1 of the first flange or the second flange of the gasket of the button cell to the conditions specified in the present application, the internal contact of the battery can be increased, the stability of the battery can be improved, and the internal contact caused by the positive cover bulging under high-temperature environment can be effectively prevented, so that the characteristics of the button cell will not be deteriorated, and the stability of the battery performance is higher.

[0279] Comparing Example 2 and Comparative Example 5, the length of the gasket part of the gasket of the button cell of Example 2 is set as 0.91*(D4-2t1)*cosθ2, and the length of the gasket part of the gasket of the button cell of Comparative Example 5 is set as (D4-2t1)*cosθ2. According to the data in Table 2, when the length of the gasket part is too long, the initial internal resistance of the button cell of Comparative Example 5 is close to that of the button cell of Example 2, but after 1 week of high-temperature storage at 125℃, the internal resistance increase rate of the button cell of Comparative Example 5 is much higher than that of the button cell of Example 2. By observing the appearance of the button cell of Comparative Example 5 and the button cell of Example 2, it is found that there are obvious pits and protrusions on the positive cover of the button cell of Comparative Example 5. By placing the button cell of Comparative Example 5 and the button cell of Example 2 in a CT scan, it is found that the protrusion position of the positive cover of the button cell of Comparative Example 5 is that the length of the gasket part exceeds the positive current collector. Therefore, it can be analyzed that: since part of the length of the gasket part exceeds the positive current collector, the gasket part and the positive current collector form a kind of reinforced rib structure, which leads to different strengths of different positions of the gasket part and the positive current collector when the battery is sealed, and further leads to the outward bulging of the positive cover of the battery, the instability of the internal resistance of the button cell after high-temperature storage, and the increase of the internal resistance.

[0280] Comparing Example 2 and Comparative Example 6, the length of the gasket part of the gasket of the button cell of Example 2 is set as 0.91*(D4-2t1)*cosθ2, and the length of the gasket part of the gasket of the button cell of Comparative Example 6 is set as 0.90*D3*cosθ2. According to the data in Table 2, when the length of the gasket is too short, the initial internal resistance of the button cell of Comparative Example 6 is close to that of the button cell of Example 2, but after 1 week of high-temperature storage at 125℃, the internal resistance increase rate of the button cell of Comparative Example 6 is as high as 216%, much higher than that of the button cell of Example 2. First, by CT observation of the button cell of Comparative Example 6, it is found that one side of the gasket part is not placed in the area Q4 where the annular bottom wall of the positive current collector is located; there is a slight gap between the gasket part and the positive current collector at the outward bulging position of the positive cover. After disassembling the battery, it is found that one side of the gasket part is not placed in the area Q4 where the annular bottom wall of the positive current collector is located, and the gasket part is partially separated from the positive plate, which further leads to poor contact and increased internal resistance.

Claims

1. A button cell battery (1), comprising: A positive electrode cap assembly (220) includes a positive electrode cap (11) and a gasket (20) installed inside the positive electrode cap (11); A positive current collector (14) is disposed inside the positive electrode cover (11) and has a receiving cavity (144). A through hole (142) is provided on the bottom wall of the positive current collector (14). The positive electrode plate (15) is located inside the receiving cavity (144); The gasket (20) includes a gasket portion (21) and a spring portion (22) arranged in a cross manner. The length of the gasket portion (21) is L1, and the length of the spring portion (22) is L2, where L1 > L2. Any one or both of the spring portion (22) and the gasket portion (21) are provided with a protruding structure (23). The protruding structure (23) passes through the through hole (142) and is fixed to the positive electrode plate (15).

2. The button cell (1) according to claim 1, wherein, The gasket part (21), the spring part (22) and the protrusion structure (23) are integrally formed, and the thickness of the gasket (20) is set to t, 0.05≤t≤0.30mm.

3. The button cell (1) according to claim 1, wherein, The protruding structure (23) includes a first flange (231) and a second flange (232), which are respectively disposed at both ends of the spring piece (22).

4. The button cell (1) according to claim 3, wherein, The height of the first flange (231) or the second flange (232) is set to h1, where 2*t < h1 < 10*t; and / or, The angle formed by the extension line of the outer cross section of the first flange (231) or the second flange (232) and the plane where the spring piece (22) is located is θ1, and θ1 is set to 90°~150°.

5. The button cell (1) according to claim 1, wherein, The protrusion structure (23) includes at least two protrusions (233) disposed on the pad portion (21), and the at least two protrusions (233) are symmetrically disposed and located on both sides of the spring portion (22).

6. The button cell (1) according to claim 5, wherein, The height of the protrusion (233) is set to h2, where 1.5*t≤h2≤3*t.

7. The button cell (1) according to claim 1, wherein, The orthographic projection of the gasket (20) onto the positive electrode cover (11) is set to a cross shape, a star shape, or a combination of a circle and a cross shape.

8. The button cell (1) according to any one of claims 1 to 7, wherein, The gasket (20) is provided with a positioning hole (25), which is configured to position the gasket (20) when it is welded to the positive electrode cover (11). The gasket (20) is welded to the positive electrode cover (11) such that the concentricity of the gasket (20) and the positive electrode cover (11) is less than or equal to 0.3 mm.

9. The button cell (1) according to claim 8, wherein, There are at least two first solder joints (210) between the gasket (20) and the positive electrode cap (11), and at least two of the first solder joints (210) are symmetrically arranged with respect to the center point of the gasket (20).

10. The button cell (1) according to claim 9, wherein, The gasket (20) includes a first region (Q1), a second region (Q2a, Q2b) located on the gasket portion, and a third region (Q3a, Q3b) located on the spring portion (22). The first region (Q1) is symmetrical about the center line of the gasket portion (21) and the center line of the spring portion (22). The second region (Q2a, Q2b) includes a first part (Q2a) of the second region and a second part (Q2b) of the second region. The first part (Q2a) of the second region and the second part (Q2b) of the second region... The second part (Q2b) is located on both sides of the first region (Q1). The third region (Q3a, Q3b) includes the first part (Q3a) and the second part (Q3b) of the third region. The first part (Q3a) and the second part (Q3b) of the third region are located on both sides of the first region (Q1). The length of the first region (Q1) is d1, d1=0.5*L1, and the width of the first region (Q1) is equal to the width of the pad part (21). At least two of the first solder joints (210) are located within the first region (Q1), and / or at least two of the first solder joints (210) are located within the first portion (Q2a) and the second portion (Q2b) of the second region; and at least two of the first solder joints (210) are located outside the first portion (Q3a) and the second portion (Q3b) of the third region.

11. The button cell (1) according to any one of claims 1 to 7, wherein, The positive current collector (14) includes an annular bottom wall (141), and the two ends of the gasket portion (21) are connected to the annular bottom wall (141).

12. The button cell (1) according to claim 11, wherein, The diameter of the circumscribed circle corresponding to the edge of the gasket part (21) is set to D1. The gasket part (21) includes two gasket ends (214), one of which includes two gasket endpoints (2143). The angle between the line connecting the two gasket endpoints (2143) and the center of the gasket (20) is 2*θ2. The diameter of the through hole (142) of the positive current collector (14) is set to D3. The diameter of the annular bottom wall (141) of the positive current collector (14) is set to D4. The thickness of the positive current collector (14) is set to t3. The length L1 of the gasket part satisfies: L1=D1*cosθ2, and 1.02*D3*cosθ2≤L1≤0.98*(D4-2*t3)*cosθ2.

13. The button cell (1) according to claim 12, wherein, The gasket portion (21) includes two gasket sides (215) disposed opposite to each other, and the gasket end (214) protrudes relative to the gasket side (215); or, the gasket end (214) is flush with the gasket side (215).

14. The button cell (1) according to claim 12, wherein, The width of the pad portion (21) is set to w3, the diameter of the through hole (142) of the positive current collector (14) is set to D3, the spring portion (22) includes two spring end portions (222), one of the spring end portions (222) includes two spring endpoints (2223), the included angle between the line connecting the two spring endpoints (2223) and the center of the pad (20) is 2*θ3, and the length L2 of the spring portion satisfies: 1.5*w3≤L2≤0.98*D3*cosθ3.

15. The button cell (1) according to claim 1, wherein, The gasket portion (21) and the spring portion (22) are separately formed, and the protruding structure (23) is integrally formed with the gasket portion (21) or the spring portion (22).

16. The button cell (1) according to claim 15, wherein, The gasket portion (21) includes a gasket base (211) and a gasket boss (212) protruding from the gasket base (211). The gasket boss (212) and the gasket base (211) define a gasket receiving cavity (213), which is configured to receive a portion of the spring portion (22). Alternatively, the spring portion (22) includes a spring base (221) and a spring boss (223) protruding from the spring base (221), the spring boss (223) and the spring base (221) defining a spring receiving cavity (224), the spring receiving cavity (224) being configured to receive a portion of the pad portion (21).

17. The button cell (1) according to claim 16, wherein, The thickness of the spring piece (22) is set to t1, the height of the gasket boss (212) is set to H1, and the height H1 of the gasket boss (212) is set to be not less than the thickness t1 of the spring piece (22); and / or, the width of the spring piece (22) is set to w1, the width of the gasket boss (212) is set to w2, and the ratio between the width w2 of the gasket boss (212) and the width w1 of the spring piece (22) is (1.05~1.3):1; Alternatively, the thickness of the pad portion (21) is set to t2, and the height of the spring boss (223) is set to be not less than the thickness t2 of the pad portion (21); and / or, the width of the pad portion (21) is set to w3, and the ratio between the width of the spring boss (223) and the width w3 of the pad portion (21) is (1.05~1.3):

1.

18. The button cell (1) according to claim 17, wherein, The thickness t1 of the spring piece (22) satisfies: 0.05mm ≤ t1 ≤ 0.30mm; and / or, The thickness of the gasket portion (21) satisfies t2: 0.05 ≤ t2 ≤ 0.30 mm; and / or, The thickness t1 of the spring piece (22) is set to be the same as the thickness t2 of the pad piece (21).

19. The button cell (1) according to claim 17, wherein, The spring piece (22) is welded to the gasket piece (21), and the number of the second weld points (241) between the spring piece (22) and the gasket piece (21) is an even number.

20. The button cell according to claim 19, wherein, The spring piece (22) is welded to the gasket piece (21) in the circular welding area (Q5). The diameter of the circular welding area (Q5) is smaller than the width w1 of the spring piece (22), and the diameter of the circular welding area (Q5) is smaller than the width w3 of the gasket piece.

21. The button cell (1) according to claim 17, wherein, The protruding structure (23) includes a first flange (231) and a second flange (232) disposed on the spring plate portion (22). The first flange (231) is located at one end of the spring plate portion (22), and the second flange (232) is located at the other end of the spring plate portion (22). The first flange (231) and the second flange (232) pass through the through hole (142) and are embedded in the positive electrode plate (15).

22. The button cell (1) according to claim 21, wherein, The height of the first flange (231) or the second flange (232) is set to h1, where 2*t1 < h1 < 10*t1; and / or, The angle formed by the extension line of the outer cross section of the first flange (231) or the second flange (232) and the plane where the spring sheet substrate (221) is located is θ1, and θ1 is set to 90°~150°.

23. The button cell (1) according to claim 21, wherein, The protruding structure (23) also includes the gasket boss (212), which passes through the through hole (142) and is embedded in the positive electrode plate (15).

24. The button cell (1) according to any one of claims 15-23, wherein, The orthographic projection of the gasket (20) on the positive electrode cover (11) is set as a cross shape, wherein the orthographic projection of the spring piece (22) and the gasket (21) on the positive electrode cover (11) is set as a straight line.

25. The button cell (1) according to claim 24, wherein, The spring section (22) and the gasket section (21) are made of the same stainless steel material.

26. The button cell (1) according to claim 16, wherein, The gasket (20) is welded to the positive electrode cover (11). Both the gasket (20) and the end point (11) of the spring are set as centrally symmetrical structures, and the concentricity of the gasket (20) and the positive electrode cover (11) is no more than 0.3 mm.

27. The button cell (1) according to claim 26, wherein, The third solder joint (242) between the gasket (20) and the positive electrode cap (11) is provided as at least two, and the at least two third solder joints (242) are arranged symmetrically about the center of the gasket (20).

28. The button cell (1) according to claim 27, wherein, The gasket (20) includes a first region (Q1) formed by welding the gasket portion (21) and the spring portion (22), a second region (Q2a, Q2b) located on the gasket portion (21), and a third region (Q3a, Q3b) located on the spring portion (22). The second region (Q2a, Q2b) includes a first portion (Q2a) and a second portion (Q2b) of the second region located on two opposite first sides of the first region (Q1), respectively. The third region (Q3a, Q3b) includes a first portion (Q3a) and a second portion (Q3b) of the third region located on two opposite second sides of the first region (Q1), respectively. At least two of the third solder joints (242) are located within the first portion (Q2a) and the second portion (Q2b) of the second region; Furthermore, at least two of the third solder joints (242) are located outside the first portion (Q3a) and the second portion (Q3b) of the third region.

29. The button cell (1) according to claim 28, wherein, The distance between the at least two third solder points (242) is set to d1, 0.3*L1+0.7*w1≤d1≤0.9*L1+0.1*w1.

30. The button cell (1) according to claim 15, wherein, The positive current collector (14) includes an annular bottom wall (141), and the two ends of the gasket portion (21) are connected to the annular bottom wall (141).

31. The button cell (1) according to claim 30, wherein, The diameter of the circumscribed circle corresponding to the edge of the gasket part (21) is set to D1. The gasket part (21) includes a first end (2141) and a second end (2142). The first end (2141) includes two gasket endpoints (2143). The angle between the line connecting the two gasket endpoints (2143) and the center of the gasket part (21) is 2θ2. The diameter of the through hole (142) of the positive current collector (14) is set to D3. The diameter of the annular bottom wall (141) of the positive current collector (14) is set to D4. The thickness of the positive current collector (14) is set to t3. The length L1 of the gasket part satisfies: L1=D1*cosθ2, and 1.02*D3*cosθ2≤L1≤0.98*(D4-2t3)*cosθ2.

32. The button cell (1) according to claim 31, wherein, The spring section (22) includes a first spring end (2221) and a second spring end (2222). The first spring end includes two spring endpoints (2223). The angle between the line connecting the two spring endpoints (2223) and the center of the spring section (22) is 2θ3. The length L2 of the spring section (22) satisfies: 1.5*w3≤L2≤0.98*D3*cosθ3.

33. A method for preparing a gasket (20), configured to prepare a gasket (20) in a button cell as described in any one of claims 16-32, the method comprising: A strip-shaped assembly of multiple interconnected spring pieces (300) is prepared using a stamping process. A strip-shaped assembly of multiple interconnected gaskets (400) is prepared using a stamping process. After adjusting the spring assembly (300) and the gasket assembly (400) to coincide at their centers, the spring assembly (300) and the gasket assembly (400) are welded together using a laser welding device to form a plurality of interconnected gaskets (20).

34. A method for assembling a button cell battery, configured to assemble a button cell battery as described in any one of claims 1-32, the method comprising: After adjusting the relative position between the gasket (20) and the positive electrode cap (11), the gasket (20) and the positive electrode cap (11) are welded together to form the positive electrode cap assembly (220). The positive electrode sheet (15) is placed into the positive current collector (14) to form a positive electrode assembly (100). The negative electrode sheet (16) is placed into the negative electrode cover (12) to form a negative electrode assembly (500). A diaphragm (17) and the positive electrode assembly (100) are sequentially placed inside the negative electrode assembly (500) to form an assembly; Electrolyte (19) is injected into the assembly; The positive electrode cap assembly (220) is placed on the end of the assembly.

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