Button type battery, method of manufacturing pad assembly, and method of assembling button type battery

Abstract

To provide a button type battery capable of improving stability of an internal structure of the battery, a method of assembling the same, and a method of manufacturing a pad.SOLUTION: The present invention provides a button battery and an assembly method thereof, and a preparation method of a spacer, wherein the button battery comprises a positive electrode cover assembly comprising a positive electrode cover and a spacer, a positive electrode current collector and a positive electrode plate, wherein the spacer comprises a spacer portion and an elastic plate portion which are arranged in a staggered manner, and one or both of the elastic plate portion and the spacer portion are provided with a protrusion structure which passes through a through hole of the positive electrode current collector and is fixed to the positive electrode plate.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention claims priority from Chinese patent applications filed with the China Patent Office on June 25, 2024, bearing application numbers 202410832430.3, 202421470730.3, 202410832392.1, and 202421470638.7, and from an international application filed with the China Patent Office on September 30, 2024, bearing application number PCT / CN2024 / 123024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to battery technology, and more particularly to a button cell battery, a method for manufacturing a pad assembly, and a method for assembling a button cell battery. [Background technology]

[0003] As an energy source, a basic requirement for button batteries is the stable supply of power. High internal resistance of a button battery will result in a shortened battery life, reduced capacity, accelerated self-discharge rate, reduced voltage, and battery heat generation. Therefore, the internal resistance of a battery is generally used as one of the important indicators for evaluating the reliability and stability of a button battery. That is, the initial internal resistance of a button battery is required to be less than 10 Ω, and the internal resistance of the battery after storage at 85°C for one week must be less than 20 Ω.

[0004] With the development of society and changes in the market, the application environment for button batteries is becoming increasingly worse. For example, button batteries are required to stably supply power under high temperature, high humidity, high pressure, high frequency vibration, and high speed centrifugation. In other words, the internal resistance of the battery must be less than 15 Ω after storage for 100 hours at 125°C. Summary of the Invention [Problem to be solved by the invention]

[0005] As the storage temperature of button batteries rises from 85°C to 125°C, the positive electrode current collector structure and the assembly process between it and the positive electrode cover in the related art will cause the swelling of the positive electrode cover to increase, increasing the gap between the positive electrode current collector and the positive electrode cover, leading to poor contact between the positive electrode collector and the positive electrode cover and a reduction in the current collecting effect of the positive electrode collector, making it impossible for the battery to supply power stably and failing to meet the requirements of current button battery application scenarios. [Means for solving the problem]

[0006] In a first aspect, embodiments of the present invention provide a button cell battery, the button cell battery comprising: a positive electrode cap assembly including a positive electrode cap and a pad attached to the inside of the positive electrode cap; a positive electrode current collector provided inside the positive electrode cover, the positive electrode current collector having a storage chamber and a through-hole in the bottom wall; a positive electrode sheet located in the accommodation chamber, Here, the pad comprises a pad portion and an elastic sheet portion that are arranged crosswise, and when the length of the pad portion is L1 and the length of the elastic sheet portion is L2, L1>L2, and either or both of the pad portion and the elastic sheet portion are provided with a protrusion structure that passes through the through hole and is fixed to the positive electrode sheet.

[0007] In a second aspect, an embodiment of the present invention provides a method for manufacturing a pad of the above-mentioned button cell battery, the method comprising: manufacturing an elastic sheet set in which a plurality of the elastic sheets are connected to each other and formed into a belt shape by a press molding process; manufacturing a pad set in which a plurality of the pads are connected to each other and formed into a band shape by a press molding process; The method includes adjusting the elastic sheet set and the pad set so that their centers are aligned, and then welding the elastic sheet set and the pad set together using laser welding equipment to form a plurality of connected pads.

[0008] In a third aspect, an embodiment of the present invention provides a method for assembling the above button battery, the method comprising: After adjusting the relative position of the pad assembly and the positive electrode cover, the pad and the positive electrode cover are welded together to form a positive electrode cover assembly; placing the positive electrode sheet in a positive electrode current collector to form a positive electrode assembly; placing the negative electrode sheet in a negative electrode cap to form a negative electrode cap assembly; sequentially placing a separator and the positive electrode assembly within a negative electrode cap assembly to form an assembly; injecting an electrolyte into the assembly; and placing the positive electrode cap assembly over the end of the assembly. [Effects of the Invention]

[0009] The button battery of the present invention adds a pad to the button battery, the pad is connected to the positive electrode cover, the length of the pad portion of the pad is greater than the length of the elastic sheet portion of the pad, both ends of the pad portion are connected to the positive electrode current collector, and either or both of the elastic sheet portion and the pad portion are further provided with a protrusion structure for further fixing the positive electrode sheet. Therefore, even if the positive electrode cover swells, the positive electrode cover continues to be in contact with the positive electrode sheet inside the positive electrode current collector, thereby improving the stability of the internal structure of the battery.

[0010] The pad manufacturing method of the present invention effectively improves pad manufacturing efficiency and reduces assembly process costs by adjusting an elastic sheet set formed in a strip by connecting multiple elastic sheets and a pad set formed in a strip by connecting multiple pads so that their centers overlap, and then welding the elastic sheet set and pad set together to form multiple connected pads.

[0011] The assembly method for a button battery according to the present invention welds a pad to the positive electrode cover and uses a protrusion structure on the pad to further secure the positive electrode sheet. This allows the positive electrode cover to remain in contact with the positive electrode sheet inside the positive electrode current collector even if the positive electrode cover bulges, thereby improving the stability of the internal structure of the battery. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a button battery according to an embodiment of the present invention, taken from one angle; [Figure 2] 2 is a cross-sectional view of a button battery according to an embodiment of the present invention from another angle. FIG. [Figure 3] 4 is a cross-sectional view of a button battery according to another embodiment of the present invention, taken from one angle; FIG. [Figure 4] 1 is a perspective view of a pad according to an embodiment of the present invention; [Figure 5a] FIG. 2 is a material supply tape diagram of a pad assembly according to one embodiment of the present invention. [Figure 5b] FIG. 10 is a material supply tape diagram of a pad assembly according to another embodiment of the present invention. [Figure 6] 1 is a cross-sectional view of an elastic sheet according to an embodiment of the present invention, taken from one angle. [Figure 7a] FIG. 7 is an enlarged view of a portion of FIG. 6 according to one embodiment of the present invention. [Figure 7b] 7 is an enlarged view of a portion of FIG. 6 according to another embodiment of the present invention. [Figure 8] 4 is a cross-sectional view of a pad according to an embodiment of the present invention from another angle. [Figure 9a] FIG. 10 is a perspective view of a pad according to a second embodiment of the present invention. [Figure 9b] FIG. 10 is a perspective view of a pad according to a third embodiment of the present invention. [Figure 9c] FIG. 10 is a perspective view of a pad according to a fourth embodiment of the present invention. [Figure 9d] FIG. 10 is a perspective view of a pad according to a fifth embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view of the pad and the positive electrode cover after being welded together according to the embodiment of the present invention. [Figure 11] FIG. 10 is a cross-sectional view of the pad and the positive electrode cover after being welded together according to an embodiment of the present invention. [Figure 12] FIG. 10 is a front view of the pad and the positive electrode cover after they are welded together according to an embodiment of the present invention. [Figure 13] 10A and 10B are diagrams showing positions of welding points between a pad and a positive electrode cover according to an embodiment of the present invention. [Figure 14] FIG. 2 is a schematic view of a pad and a positive electrode current collector according to an embodiment of the present invention, viewed from one angle. [Figure 15a] FIG. 2 is a line schematic diagram of a pad configuration according to one embodiment of the present invention. [Figure 15b] FIG. 10 is a line schematic diagram of a pad configuration according to another embodiment of the present invention. [Figure 16] 10 is a schematic diagram showing the position of the pad and the positive electrode current collector according to the embodiment of the present invention from another angle. FIG. [Figure 17] 1 is a cross-sectional view of a pad and a positive electrode current collector according to an embodiment of the present invention. [Figure 18a] FIG. 10 is a schematic diagram showing the positions of a pad and a positive electrode current collector according to a comparative example of the present invention. [Figure 18b] FIG. 10 is a schematic diagram showing the positions of a pad and a positive electrode current collector according to another comparative example of the present invention. [Figure 19] 3 is a dimensional schematic diagram of a pad according to an embodiment of the present invention. FIG. [Figure 20a] 1 is a cross-sectional view of a pad according to a first embodiment of the present invention. [Figure 20b] FIG. 1 is a cross-sectional view of a pad according to Comparative Example 1 of the present invention. [Figure 20c] FIG. 10 is a cross-sectional view of a pad according to Comparative Example 2 of the present invention. [Figure 21] 1 is a cross-sectional view of a button cell battery according to an embodiment of the present invention from one perspective. [Figure 22] 2 is a cross-sectional view of a button cell battery according to an embodiment of the present invention from another perspective. [Figure 23] 1 is a cross-sectional view of a button cell battery according to another embodiment of the present invention. [Figure 24] 4 is a cross-sectional view of a button cell battery according to another embodiment of the present invention from another perspective. [Figure 25] 1 is a perspective view of a pad according to one embodiment of the present invention; [Figure 26a] FIG. 2 is a perspective view of a pad portion according to an embodiment of the present invention, viewed from one angle. [Figure 26b] FIG. 10 is a perspective view of a pad portion according to an embodiment of the present invention from another angle. [Figure 26c] FIG. 10 is a perspective view of the pad portion according to the embodiment of the present invention from another angle. [Figure 27a] FIG. 2 is a perspective view of an elastic sheet portion according to an embodiment of the present invention, viewed from one angle. [Figure 27b] FIG. 10 is a perspective view of the elastic sheet portion according to the embodiment of the present invention, viewed from another angle. [Figure 27c] FIG. 10 is a cross-sectional view of the elastic sheet portion according to the embodiment of the present invention from another angle. [Figure 27d] FIG. 10 is a perspective view of an elastic sheet portion according to another embodiment of the present invention. [Figure 28] 5 is a schematic diagram of a welding region between an elastic sheet portion and a pad portion according to an embodiment of the present invention. FIG. [Figure 29a] FIG. 27c is an enlarged view of a portion of the first structure. [Figure 29b] FIG. 27d is an enlarged view of a portion of the second structure of FIG. 27c. [Figure 29c] FIG. 27c is an enlarged view of a portion of the third structure. [Figure 30] 1 is a partial cross-sectional view of a button battery according to an embodiment of the present invention. [Figure 30a] FIG. 2 is a partial cross-sectional view of a button cell battery according to a comparative example of the present invention. [Figure 30b] FIG. 10 is a partial cross-sectional view of a button cell battery according to another comparative example of the present invention. [Figure 31] 1 is a schematic diagram of a welding area between a pad and a positive electrode cover according to the present invention. FIG. [Figure 32a] FIG. 10 is a perspective view of a pad according to another embodiment of the present invention. [Figure 32b] FIG. 10 is a perspective view of a pad according to yet another embodiment of the present invention. [Figure 33]FIG. 10 is a cross-sectional view of a pad according to an embodiment of the present invention after being welded to a positive electrode cover. [Figure 34] FIG. 2 is a perspective view of a pad according to an embodiment of the present invention after being welded to a positive electrode cover. [Figure 35] FIG. 10 is a diagram showing required positions of the second welding points between the pad and the positive electrode cover according to an embodiment of the present invention. [Figure 36a] 1 is a cross-sectional view of a button cell battery according to an embodiment of the present invention when the positive electrode cover is swollen. FIG. [Figure 36b] FIG. 10 is a cross-sectional view of a button battery according to an embodiment of the present invention when the positive electrode cover is swollen, as viewed from another angle. [Figure 37] 1 is a schematic diagram of the positional structure of a pad and a positive electrode current collector according to an embodiment of the present invention; [Figure 38] 2 is a schematic diagram of the positional structure of a pad and a positive electrode current collector according to an embodiment of the present invention; [Figure 39] 3 is a schematic diagram of the positional structure of the pad and the positive electrode current collector according to an embodiment of the present invention; [Figure 40] 4 is a schematic diagram of the positional structure of the pad and the positive electrode current collector according to an embodiment of the present invention; [Figure 41] FIG. 2 is a line schematic diagram of a pad configuration according to one embodiment of the present invention. [Figure 42a] 5 is a schematic diagram of the positional structure of the pad and the positive electrode current collector according to an embodiment of the present invention. [Figure 42b] FIG. 10 is a schematic diagram showing the positional structure of a pad and a positive electrode current collector according to a comparative example of the present invention. [Figure 42c] FIG. 10 is a schematic diagram showing the positional structure of a pad and a positive electrode current collector according to another comparative example of the present invention. [Figure 43a] 1 is a schematic diagram showing the structure of a raw material of a pad set according to an embodiment of the present invention; [Figure 43b] 1 is a schematic diagram showing the structure of a raw material of an elastic sheet set according to an embodiment of the present invention; [Figure 43c] 1 is a structural schematic diagram of a raw material of a pad assembly according to an embodiment of the present invention; [Figure 44a] 1 is a schematic diagram showing a partial structure of an elastic sheet part according to Example 1 of the present invention. [Figure 44b] FIG. 2 is a partial structural schematic view of an elastic sheet part according to Comparative Example 1 of the present invention. [Figure 44c] FIG. 10 is a partial structural schematic view of an elastic sheet part according to Comparative Example 2 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Example 1] In the present invention, unless otherwise stated, directional terms used, such as "up" and "down", generally refer to up and down in the actual use or operation state of the device, specifically in the drawing direction, and "in" and "out" are relative to the profile of the device.

[0014] A button battery mainly comprises a positive electrode cap, a negative electrode cap, a sealing ring, a positive electrode current collector, a positive electrode sheet, a negative electrode active material, a separator, and an electrolyte. In the related art, taking into consideration the cost of the battery assembly process, the positive electrode sheet is usually placed inside the positive electrode current collector, and then the positive electrode current collector is placed inside the positive electrode cap, and the positive electrode cap is tightly attached to the positive electrode current collector by sealing and crimping.

[0015] Because the positive electrode current collector is placed directly inside the positive electrode cover and there is no position-limiting structure between the positive electrode current collector and the positive electrode cover, the positive electrode current collector is prone to movement inside the button battery, and the positive electrode current collector can become significantly misaligned, especially under severe vibration or high-speed centrifugation, resulting in poor contact between internal components and the button battery being prone to problems such as current fluctuation, low voltage, low capacity, and high resistance.In addition, when the button battery is stored at high temperatures, the positive electrode cover swells, forming a gap between the positive electrode current collector and the positive electrode cover, resulting in poor contact between internal components and the button battery suffering from low voltage, poor discharge, and high internal resistance.

[0016] As an energy source, a basic requirement for button batteries is the stable supply of power. High internal resistance of a button battery will result in a shortened battery life, reduced capacity, accelerated self-discharge rate, reduced voltage, and battery heat generation. Therefore, the internal resistance of a battery is generally used as one of the important indicators for evaluating the reliability and stability of a button battery. That is, the initial internal resistance of a button battery must be less than 10 Ω, and the internal resistance of the battery after storage at 85°C for one week must be less than 20 Ω.

[0017] With the development of society and changes in the market, the application environment for button batteries is becoming increasingly worse. For example, button batteries are required to stably supply power under high temperature, high humidity, high pressure, high frequency vibration, and high speed centrifugation. In other words, the internal resistance of the battery must be less than 15 Ω after storage for 100 hours at 125°C.

[0018] However, as the storage temperature of button batteries rises from 85°C to 125°C, the positive electrode current collector structure and the assembly process between it and the positive electrode cover in the related art cause an increase in swelling of the positive electrode cover, increasing the gap between the positive electrode current collector and the positive electrode cover, which in turn leads to poor contact between the positive electrode collector and the positive electrode cover and a decrease in the current collecting effect of the positive electrode collector, and further causes a sharp increase in the internal resistance of the battery, which cannot meet the requirements of current button battery application scenarios.

[0019] In order to improve the stability of the electrical performance of the button battery in extreme environments, the present invention optimizes the internal structure of the button battery to improve the current collection effect.

[0020] 1 to 3, the present invention provides a button battery 1, which includes a positive electrode cover 11, a negative electrode cover 12, a seal ring 13, a positive electrode current collector 14, a positive electrode sheet 15, a negative electrode sheet 16, a separator 17, and an electrolyte 19.

[0021] The positive electrode cover 11 has an open lid-like structure. As shown in Fig. 3, the outer surface of the positive electrode cover 11 may be configured as an upright surface structure, or as shown in Fig. 1, the outer surface of the positive electrode cover 11 may be provided with a boss structure.

[0022] The negative electrode lids 12 each have an open lid-like structure, and the inner and outer diameters of the positive electrode lid 11 are both larger than the inner and outer diameters of the negative electrode lid 12 so that the positive electrode lid 11 can cover the outside of the negative electrode lid 12.

[0023] The seal ring 13 is provided at the connection point between the positive electrode lid 11 and the negative electrode lid 12, and is configured to enclose at least a part of the wall of the negative electrode lid 12 so that the positive electrode lid 11 and the negative electrode lid 12 are hermetically connected. At the same time, the seal ring 13 functions to insulate the positive electrode lid 11 and the negative electrode lid 12 from each other.

[0024] The positive electrode current collector 14 is accommodated in the inner chamber of the positive electrode lid 11. The positive electrode current collector 14 may be any one of a current collecting ring, a current collecting mesh, and a current collecting sheet. As shown in FIG. 1 , the positive electrode current collector 14 is a current collecting ring, and includes an annular bottom wall 141 and a side wall 143 circumferentially connected to the top of the annular bottom wall 141. The annular bottom wall 141 and the side wall 143 surround and form a storage chamber 144. A through hole 142 is formed in the annular bottom wall 141. The inner diameter of the positive electrode current collector 14 is smaller than the inner diameter of the negative electrode lid 12.

[0025] The positive electrode sheet 15 is accommodated inside the accommodation chamber 144 of the positive electrode current collector 14 and contacts the positive electrode cover 11 through the through-hole 142 .

[0026] The negative electrode sheet 16 is housed in the inner chamber of the negative electrode cover 12 .

[0027] The separator 17 is provided between the positive electrode sheet 15 and the negative electrode sheet 16, and separates the positive electrode sheet 15 from the negative electrode sheet 16. The orthogonal projection plane of the negative electrode sheet 16 onto the separator 17 and the orthogonal projection plane of the positive electrode sheet 15 onto the separator 17 roughly coincide with each other.

[0028] The electrolyte 19 is filled inside the entire button battery 1, and after the electrolyte is injected, the internal structure, such as the negative electrode sheet and positive electrode sheet, is immersed in the electrolyte, and the charged ions in the positive electrode sheet and negative electrode sheet communicate with each other via the electrolyte.

[0029] Continuing to refer to Figures 1 to 3, the button battery 1 further includes a pad 20 connected to the inner surface of the positive electrode cover 11, and the pad 20 includes a pad portion 21 and an elastic sheet portion 22 arranged crosswise, the length L1 of the pad portion 21 is greater than the length L2 of the elastic sheet portion 22, both ends of the pad portion 21 are connected to the positive electrode current collector 14, the elastic sheet portion 22 is located inside the positive electrode current collector 14, and either or both of the elastic sheet portion 22 and the pad portion 21 are provided with a protrusion structure 23 for fixing the positive electrode sheet 15.

[0030] A pad 20 is added to the button battery 1, and the pad 20 is connected to the positive electrode cover 11. The length of the pad portion 21 of the pad 20 is greater than the length of the elastic sheet portion 22 of the pad 20. Both ends of the pad portion 21 are connected to the positive electrode current collector 14, and the elastic sheet portion 22 is located inside the positive electrode current collector 14. One or both of the elastic sheet portion 22 and the pad portion 21 are further provided with a protrusion structure 23 for further fixing the positive electrode sheet 15. Thus, the pad 20 is configured to be connected to the positive electrode cover 11 and the positive electrode current collector 14, respectively, and the protrusion structure 23 of the pad 20 is used to further fix the positive electrode sheet 15. Therefore, when the positive electrode cover 11 swells, the positive electrode cover 11 can continue to contact the positive electrode sheet 15 inside the positive electrode current collector 14, thereby improving the stability of the internal structure of the battery.

[0031] 4 and 6, the pad portion 21, elastic sheet portion 22 and protrusion structure 23 of the pad 20 are integrally molded, and the thickness of the pad 20 is t, where 0.05 mm≦t≦0.30 mm.

[0032] The material used to form the pad 20 may be one of SUS44, SUS304, SUS430, SUS316, and SUS444. In one specific implementation, the pad 20 is made of SUS430 and configured to have magnetic properties, which is advantageous in reducing the difficulty of welding the pad 20 to the positive electrode cover 11 or the positive electrode current collector 14 and improving the feasibility of welding.

[0033] The thickness of the pad 20 is set to 0.05 mm to 0.30 mm, and in some embodiments, to 0.10 mm to 0.20 mm. In a specific implementation, the thickness of the pad 20 may be 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, or any two of the above values, or any range between the above values. The inventors have found through research that if the thickness of the pad 20 is less than 0.05 mm, the pad 20 has low strength and is easily deformed, and is unable to exert its elastic connecting function. If the thickness of the pad 20 is more than 0.30 mm, the pad 20 increases in volume, occupies the internal space of the battery, and results in a decrease in battery capacity.

[0034] As shown in Figures 5a and 5b, the present invention further provides a pad manufacturing method, in which the pad is processed and formed using a press molding process, and during the pressing process, multiple pads 20 are rolled from a material with their edges connected to form a roll-shaped multiple pad assembly 200. Continuing with Figure 5a, the multiple pads 20 are connected by connecting the edges of the material, and the single pad 20 formed after two adjacent pads 20 are cut still has protruding ends on its side edges. Continuing with Figure 5b, the multiple pads 20 are directly connected, and the single pad 20 formed after two adjacent pads 20 are cut is configured so that its side edges are flush.

[0035] Continuing to refer to FIG. 4, the protrusion structure 23 provided on the pad 20 for fixing the positive electrode sheet 15 includes a first flange 231 and a second flange 232, and the first flange 231 and the second flange 232 are located at both ends of the elastic sheet portion 22, respectively.

[0036] By providing a first flange 231 and a second flange 232 at both ends of the elastic sheet portion 22, the first flange 231 and the second flange 232 can be fitted into the positive electrode sheet 15. Providing the protrusion structures 23 at both ends of the elastic sheet portion 22 increases the contact area between the pad 20 and the positive electrode sheet 15 compared to providing the protrusion structures 23 at other positions on the elastic sheet portion 22, thereby improving the positional restriction effect of the protrusion structures 23 and the positive electrode sheet 15. In particular, when the button battery 1 is subjected to extreme vibration or centrifugation, the first flange 231 and the second flange 232 effectively reduce the positional movement of the positive electrode current collector 14 and the pad 20 within the battery, reducing the mutual impact force between the battery positive electrode plate 15, the negative electrode plate 16, and the electrolyte, thereby reducing the internal resistance of the battery and improving the stability of battery performance.

[0037] As shown in FIG. 6, when the height of the first flange 231 or the second flange 232 is set to h1, 2*t≦h1≦h10*t is satisfied, and the angle formed between the extension line of the outer cut surface of the first flange 231 or the second flange 232 and the plane on which the elastic sheet portion 22 is located is 90° to 150°.

[0038] In some embodiments, the first flange 231 and the second flange 232 are provided symmetrically with respect to the center of the pad 20, and the protruding height of the first flange 231 from the base surface 24 of the elastic sheet portion 22 and the protruding height of the second flange 232 from the base surface 24 of the elastic sheet portion 22 are the same and are both set to h1. In some examples, h1 may be 2t, 3t, 4t, 5t, 6t, 7t, 8t, 9t, 10t, a value between any two of the above values, or a numerical 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 height h1 of the second flange 232 satisfies 2*t≦h1≦10*t, after the first flange 231 and the second flange 232 are fitted into the positive electrode sheet 15, the entire positive electrode sheet 15 is not damaged by the first flange 231 or the second flange 232, causing the sheet to break or fall off, and the first flange 231 and the second flange 232 are not deformed in the process of fitting into the positive electrode sheet 15. Specifically, when the height h1 of the first flange 231 or the second flange 232 is < 2t, the first flange 231 or the second flange 232 is not fitted into the positive electrode sheet 15 to an insufficient depth, and if the positive electrode cover 11 bulges outward, the first flange 231 or the second flange 232 is likely to detach from the positive electrode sheet 15, causing poor contact between the entire pad 20 and the positive electrode current collector 14. If the height h1 of the first flange 231 or the height h1 of the second flange 232 is greater than 10t, the first flange 231 and the second flange 232 are fitted deep into the positive electrode sheet 15, and therefore, in the process of fitting the first flange 231 or the second flange 232 into the positive electrode sheet 15, the pad 20 is likely to deform and the entire positive electrode sheet 15 is likely to be damaged.

[0039] Continuing to refer to Figure 6, if the angle between the extension line of the outer cut surface of the first flange 231 or the second flange 232 and the plane on which the elastic sheet portion 22 is located is θ1, then θ1 must satisfy 90°≦θ1≦150°.

[0040] In a specific implementation, the first flange 231 or the second flange 232 is disposed symmetrically with respect to the center of the pad 20, and the angle formed between an extension of the outer cut surface of the first flange 231 and the plane on which the elastic sheet portion 22 is located is the same as the angle formed between an extension of the outer cut surface of the second flange 232 and the plane on which the elastic sheet portion 22 is located, and both are set to θ1, where θ1 must satisfy 90°≦θ1≦150°. For example, θ1 may be 90°, 100°, 110°, 120°, 130°, 140°, 150°, or any two of the angles above, or any range of angles between the two angles above. Through research, the inventors have discovered that if θ1<90°, it is difficult for the first flange 231 or the second flange 232 to be fitted into the positive electrode sheet 15, and if θ1>150°, the range over which the first flange 231 or the second flange 232 is fitted into the positive electrode sheet 15 is too large, making the entire positive electrode sheet 15 prone to damage and causing powder shedding.

[0041] The first flange 231 or the second flange 232 may have a linear inclined structure. As shown in Fig. 7a, the first flange 231 or the second flange 232 may have a wave-shaped inclined structure. As shown in Fig. 7b, the first flange 231 or the second flange 232 may have an inclined structure with a pointed end.

[0042] Continuing to refer to FIGS. 4 and 8, the protrusion structure 23 comprises at least two protrusions 233 provided on the pad portion 21, and the at least two protrusions 233 are provided symmetrically on both sides of the elastic sheet portion 22, respectively.

[0043] By providing at least two protrusions 233 on the pad portion 21, the two protrusions 233 are further embedded in the positive electrode sheet 15, increasing the contact area between the pad 20 and the positive electrode sheet 15 and enhancing the restricting effect of the protrusion structure 23 and the positive electrode sheet 15. Even when the button battery 1 is subjected to extreme vibration or centrifugation, the protrusion structure 23 effectively prevents relative displacement between the positive electrode current collector 14 and the pad 20 inside the button battery 1, further 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 battery 1 and ultimately improving the stability of the electrical performance of the button battery 1.

[0044] The pad portion 21 is provided with two protrusions 233 that are provided symmetrically with respect to the elastic sheet portion 22, and a first flange 231 and a second flange 232 that are provided symmetrically with respect to the pad portion 21 are provided at both ends of the elastic sheet portion 22. The pad portion 21 and the elastic sheet portion 22 are provided so as to intersect with each other, the two protrusions 233 are configured to fix the positive electrode sheet 15 in a first direction, and the first flange 231 and the second flange 232 are configured to fix the positive electrode sheet 15 in a second direction, and the positive electrode sheet 15 is fixed by the pad 20 in both the first direction and the second direction, so that the pad 20 can sufficiently limit displacement of the positive electrode sheet 15 with respect to the pad 20 in extreme environments.

[0045] As shown in FIG. 8, the height of the protrusion 233 is set to h2, where 1.5*t≦h2≦3*t.

[0046] In a specific implementation, the height h2 of the protrusions 233 relative to the plane on which the pad portion 21 is located may be set to 1.5t, 2.0t, 2.5t, 3.0t, or any two of the above values, or any range between the two values. The inventors have found through research that if the height h2 of the protrusions 233 is less than 1.5t, the two protrusions 233 are not inserted deep enough into the positive electrode sheet 15, and when the positive electrode cover 11 bulges outward, the two protrusions 233 are likely to detach from the positive electrode sheet 15, resulting in poor contact between the entire pad 20 and the positive electrode current collector 14. If the height h2 of the two protrusions 233 is greater than 3*t, the two protrusions 233 are inserted deep enough into the positive electrode sheet 15, making it difficult to insert the two protrusions 233 into the positive electrode sheet 15 and causing the entire positive electrode sheet 15 to be easily damaged and resulting in powder falling off.

[0047] The overall shape of the two protrusions 233 may be a triangular pyramid or a polygonal columnar structure having a pointed structure.

[0048] Continuing to refer to FIG. 4 and FIGS. 9a to 9d, the orthogonal projection of the pad 20 on the positive electrode cover 11 is a cross shape, an U shape, or a combination of a circle and a cross shape.

[0049] The base surface 24 of the pad 20 can have a cross-shaped structure, and the pad portion 21 and the elastic sheet portion 22 form an intersection by being intersected, the pad portion 21 having a first portion of the pad portion 21 and a second portion of the pad portion 21 that are arranged symmetrically with respect to the intersection, and the elastic sheet portion 22 having a first portion of the elastic sheet portion 22 and a second portion of the elastic sheet portion 22 that are arranged symmetrically with respect to the intersection.

[0050] In some examples, the base surface 24 of the pad 20 has a regular cross-shaped structure in which the two portions of the pad portion 21 and the two portions of the elastic sheet portion 22 are all configured as regular rectangular structures, as shown in Fig. 4. In other select examples, the base surface 24 of the pad 20 may have an irregular cross-shaped structure, such as an irregular cross-shaped structure in which both side edges of the two portions of the pad portion 21 are configured as arc structures, as shown in Fig. 9a, or an irregular cross-shaped structure in which both portions of the pad portion 21 are configured as fan structures and the two portions of the elastic sheet portion 22 are also configured as fan structures, as shown in Fig. 9b, or an irregular cross-shaped structure in which the base surface 24 of the pad 20 has an outer ring portion configured as a closed circular ring structure and an inner portion configured as a cross-shaped structure, and both ends of the pad portion 21 are connected to the edges of the ring, as shown in Fig. 9c. Continuing to refer to FIG. 9d, the base surface 24 of the pad 20 has a U-shaped structure or other polygonal structure, and has multiple extensions on the outside connected to the intersections, i.e., a third extension, a fourth extension or a fifth extension is further provided between the pad portion 21 and the elastic sheet portion 22, and the length of the pad portion 21 is greater than the length of the elastic sheet portion 22, the length of the third extension and the length of the fourth extension.

[0051] Continuing to refer to Figures 10 to 12, the pad 20 is provided with a positioning hole 25, which functions to position the pad 20 when welding it to the positive electrode cover 11, and the pad 20 is welded to the inner surface of the positive electrode cover 11, so that the concentricity between the pad 20 and the positive electrode cover 11 is 0.3 mm or less.

[0052] The pad 20 is connected to the inner surface of the positive electrode cover 11 by welding, a positioning hole 25 is provided in the center of the pad 20, the intersection area between the pad portion 21 and the elastic sheet portion 22 is located at the center of the pad 20, and the positioning hole 25 is located at the center of the intersection area between the pad portion 21 and the elastic sheet portion 22.

[0053] The roll-shaped pad assembly 200 shown in Figures 5a and 5b is transferred to a laser welding device and cut into single pads 20, and the positive electrode cover 11 is fed by a vibrating plate and placed in a jig. In the process of welding the pad 20 and the positive electrode cover 11 together, the jig grasps the positioning hole 25 of the pad 20, places the pad 20 on the inner surface of the positive electrode cover 11, and positions it in the center by the positioning hole 25, and then the pad 20 and the positive electrode cover 11 are welded together by laser welding.

[0054] During the assembly process, the concentricity between the pad 20 and the positive electrode cover 11 must be controlled to be ≦0.3 mm, and in some embodiments, the concentricity between the pad 20 and the positive electrode cover 11 is ≦0.1 mm. The inventors have found through research that if the concentricity between the positive electrode cover 11 and the pad 20 is greater than 0.3 mm, the misalignment between the pad 20 and the positive electrode cover 11 will be severe, which will further severely misalign the pad 20 and the positive electrode current collector 14, thereby reducing the current collecting effect of the positive electrode current collector 14 and further affecting the electrical performance of the button battery 1.

[0055] As shown in FIG. 13, there are at least two first weld points 210 formed by welding the pad 20 and the positive electrode cover 11 together, and the at least two first weld points 210 are provided symmetrically with respect to the center of the pad 20 .

[0056] The inventors have found through research that in the process of welding the pad 20 and the positive electrode cover 11, the number of first weld points 210 formed by welding the pad 20 and the positive electrode cover 11 is set to two, and that the two first weld points 210 contribute to improving the welding strength between the pad 20 and the positive electrode cover 11. If the number of first weld points 210 formed by welding the pad 20 and the positive electrode cover 11 is one, the pad 20 is likely to shift in position and warp relative to the positive electrode cover 11, and if the number of first weld points 210 formed by welding the pad 20 and the positive electrode cover 11 exceeds two, the welding process between the pad 20 and the positive electrode cover 11 becomes complicated and the welding costs increase.

[0057] Still referring to FIG. 13, by optimizing the position of the welding area between the pad 20 and the positive electrode cover 11, the stability performance of the button battery 1 can be further improved.

[0058] The base surface 24 of the pad 20 for welding is divided into five regions, namely, a first region Q1, a second region first portion Q2a, a second region second portion Q2b, a third region first portion Q3a, and a third region second portion Q3b. The first region Q1 is located at the intersection of the pad portion 21 and the elastic sheet portion 22. The second region first portion Q2a and the second region second portion Q2b are provided on both sides of the first region Q1 and are located in the pad portion 21. The third region first portion Q3a and the third region second portion Q3b are provided on both sides of the first region Q1 and are located in the elastic sheet portion 22. If the length of the pad portion 21 is L1, the length d1 of the first region Q1 extending along the pad portion 21 satisfies d1 = 0.5 * L1, and the width of the first region Q1 extending along the elastic sheet portion 22 is equal to the width of the pad portion 21.

[0059] The position of the first welding point 210 between the pad 20 and the positive electrode cover 11 may be provided in the first region Q1 or the second region first portion Q2a and the second region second portion Q2b. In some specific implementations, the first welding point 210 between the pad 20 and the positive electrode cover 11 is located in the second region first portion Q2a and the second region second portion Q2b, and is located outside the third region first portion Q3a and the third region second portion Q3b. Through research, the inventor discovered that when the first welding point 210 between the pad 20 and the positive electrode cover 11 is located in the first part Q3a of the third region and the second part Q3b of the third region, the elasticity of the first part Q3a of the third region and the second part Q3b of the third region where the pad 20 is located is lost, and when the positive electrode cover 11 expands, the area where the first flange 231 and the second flange 232 of the pad 20 are located is welded to the positive electrode cover 11, so that the first flange 231 and the second flange 232 are separated from the positive electrode sheet 15, further causing poor contact between the pad 20 and the positive electrode sheet 15, and the positional restriction function of the positive electrode sheet 15 by the first flange 231 and the second flange 232 becomes ineffective.

[0060] The present invention further provides a method for assembling a button battery, the method comprising: welding the cathode cap 11 and the pad 20 together to form a cathode cap assembly 220; A positive electrode sheet 15 is press-fitted into the inner chamber of the positive electrode current collector 14 to form a color positive electrode; The negative electrode is placed in the inner chamber of the negative electrode cover 12, and then the separator 17 and the colored positive electrode are placed in that order. The sealing ring 13 is wrapped around the outer surface of the negative electrode cover 12, and after the electrolyte is injected, the positive electrode cover assembly 220 is placed on top and sealed to form the button battery 1. After assembly, the button battery 1 is pre-discharged and aged.

[0061] The pad 20 is welded to the inner surface of the positive electrode cover 11, and the positive electrode current collector 14 is placed on the pad 20. However, the positions of the positive electrode current collector 14 and the pad 20 are not completely concentric, i.e., there is a misalignment between the center of the positive electrode current collector 14 and the center of the pad 20.

[0062] As shown in FIGS. 14 to 17, the positive electrode current collector 14 has an annular bottom wall 141, through holes 142 are formed in the annular bottom wall 141, and both ends of the pad portion 21 are connected to the annular bottom wall 141.

[0063] 15a, 15b, 16, and 17, the diameter of the circumscribed circle corresponding to the edge of the pad portion 21 is set to D1, the diameter of the circumscribed circle corresponding to the edge of the elastic sheet portion 22 is set to D2, the diameter of the through hole 142 of the positive electrode current collector 14 is set to D3, the diameter of the annular bottom wall 141 of the positive electrode current collector 14 is set to D4, the thickness of the positive electrode current collector 14 is set to t1, the pad portion 21 has two ends, the side edge on which one of the ends is located has two endpoints, and the included angle between the lines connecting each of the two endpoints and the center of the pad 20 is 2θ2.

[0064] Continuing to show in FIG. 15a, in one embodiment, the pad portion 21 has two pad side edges 215, each of which has a protruding pad end 214, and the side edge on which the pad end 214 is located has two pad end points 2143, and the included angle between the lines connecting each of the two pad end points 2143 and the center of the pad 20 is set to 2θ2.

[0065] Continuing to refer to FIG. 15b, in another embodiment, the pad portion 21 has two pad side edges 215, which are configured as straight edges, and the pad end portion 214 consists of the pad side edges 215 and has two pad endpoints, and the included angle between the lines connecting each of the two pad endpoints and the center of the pad 20 is set to 2θ2.

[0066] To ensure that both ends of the pad portion 21 of the pad 20 always remain in contact with the annular bottom wall 141 of the positive current collector 14, i.e., that both ends of the pad portion 21 are always located in the region Q3 where the annular bottom wall 141 of the positive current collector 14 is located, and that both ends of the pad portion 21 are still overlapping and joined in the region 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 pad portion 21 must satisfy L1=D1*cosθ2, 1.02*D3≦L1 / cosθ2≦0.98*(D4-2t1), i.e., 1.02*D3*cosθ2≦L1≦0.98*(D4-2t1)*cosθ2.

[0067] 18a, when the length of pad portion 21 is L1a, if L1a > 0.98 * (D4 - 2t1) * cos θ2, then as shown in excess region 23a of FIG. 18a, at least a portion of the region where one flange of pad 20 is located extends beyond the edge of positive current collector 14, and as shown in non-excess region 23b of FIG. 18a, the region where the other flange of pad 20 is located does not extend beyond the edge of positive current collector 14. During the sealing process of button battery 1, the strength of the edge of positive current collector 14 is greater than the strength of the plane on which the bottom wall of positive current collector 14 is located. Therefore, the height of excess region 23a of pad 20 that extends beyond the edge of positive current collector 14 becomes greater than the height of non-excess region 23b of pad 20 that does not extend beyond the edge of positive current collector 14. This creates a step inside positive current collector 14, thereby reducing the current collecting effect of positive current collector 14.

[0068] 18b, when the length of the pad portion 21 is L1b, if L1b<1.02*D3*cosθ2, then as shown in the excess region 23a of FIG. 18b, the area where one flange of the pad 20 is located exceeds the area where the through-hole 142 of the positive current collector 14 is located, and as shown in the non-excess region 23b of FIG. 18b, the other flange of the pad 20 is located in the flat area where the bottom wall of the positive current collector 14 is located. During the sealing process of the button battery 1, the height corresponding to the position of one flange of the pad 20 in the excess region 23a where the through-hole 142 of the positive current collector 14 is located becomes larger than the height corresponding to the position of the other flange of the pad 20 in the non-excess region 23b of the flat area where the bottom wall of the positive current collector 14 is located. This creates a step inside the positive current collector 14, thereby reducing the current collecting effect of the positive current collector 14.

[0069] Continuing to refer to Figures 15a, 15b, 17 and 19, the length of the pad portion 21 is set to L1, the length of the elastic sheet portion 22 is set to L2, the width extending along the extension direction of the elastic sheet portion 22 of the pad portion 21 is set to w3, the elastic sheet portion 22 has two elastic sheet ends 222, each elastic sheet end 222 has two elastic sheet end points 2223, the included angle between the lines connecting each of the two elastic sheet end points 2223 and the center of the pad 20 is set to 2*θ3, and the diameter of the through hole 142 of the positive electrode current collector 14 is set to D3.

[0070] The first flange 231 and the second flange 232 of the pad 20 are configured as an inclined structure with a certain inclination angle. When the button battery 1 is packaged, the first flange 231 and the second flange 232 are fitted into the positive electrode sheet 15 to restrict the position of the positive electrode sheet 15. Through research, the inventors have found that, in the event of misalignment between the pad 20 and the positive electrode current collector 14 or the positive electrode cover 11 bulging outward, the length of the elastic sheet portion 22 is L2, and L2 satisfies 1.5*w3≦L2≦0.98*D3*cosθ3 to ensure that the first flange 231 and the second flange 232 of the pad 20 are still fitted into the positive electrode sheet 15 and maintain an elastic connection with the positive electrode sheet 15.

[0071] If the length L2 of the elastic sheet portion 22 is greater than 0.98*D3*cosθ3, the relative positional deviation between the pad 20 and the positive electrode collector 14 is large, and either or both of the first flange 231 and the second flange 232 cannot be fitted into the positive electrode sheet 15. If the length L2 of the elastic sheet portion 22 is less than 1.5*w3, when the positive electrode cover 11 bulges outward, either or both of the first flange 231 and the second flange 232 of the pad 20 move outward together with the positive electrode cover 11, and either or both of the first flange 231 and the second flange 232 detach from the positive electrode sheet 15. As a result, the pad 20 cannot elastically restrict the positive electrode collector 14, and poor contact occurs between the pad 20 and the positive electrode collector 14.

[0072] In the present invention, more specific Example 1, Comparative Example 1, and Comparative Example 2 are provided, and high-temperature storage experiments are conducted on the button batteries 1 according to Example 1, Comparative Example 1, and Comparative Example 2 to further verify the changes in the internal resistance of the batteries in high-temperature environments according to Example 1, Comparative Example 1, and Comparative Example 2.

[0073] Example 1 The button battery 1 of Example 1 includes a pad 20, the cross-sectional structure of which is shown in Figure 20a. The base surface 24 of the pad 20 has a central cross circumferential symmetric structure, with lengths L1 = 0.91 * (D4 - 2t1) * cos θ2, L2 = 0.72 * D3 * cos θ3, t = 0.10, θ1 = 120°, and H1 = 4 * t.

[0074] Comparative Example 1 The button battery of Comparative Example 1 has a pad 20, and the cross-sectional structure of the pad 20 is as shown in Figure 20b, where the base surface 24 of the pad 20 adopts a central cross circumferential symmetric structure, with lengths L1 = 0.91 * (D4 - 2t1) * cos θ2, L2 = 0.72 * D3 * cos θ3, t = 0.10, θ1 = 120°, and H1 = 10 * t.

[0075] Comparative Example 2 The button battery of Comparative Example 2 has a pad 20, and the cross-sectional structure of the pad 20 is as shown in Figure 20c, where the base surface 24 of the pad 20 adopts a central cross circumferential symmetric structure, with lengths L1 = 0.91 * (D4 - 2t1) * cos θ2, L2 = 0.72 * D3 * cos θ3, t = 0.10, θ3 = 120°, and H1 = 2 * t.

[0076] (High temperature storage test: internal resistance evaluation) The button batteries of Example 1, Comparative Example 1, and Comparative Example 2 obtained by the above procedure were subjected to a high-temperature storage test described below to evaluate the change in internal resistance under a high-temperature environment.

[0077] Specifically, first, the internal resistance (Ω) between the positive and negative electrodes of the button batteries obtained in Example 1, Comparative Example 1, and Comparative Example 2 was measured in the same manner, and the initial resistance (Ω) is shown in Table 1 below. Next, the button batteries of Example 1, Comparative Example 1, and Comparative Example 2 were stored in a high-temperature box, the internal temperature of the high-temperature box was set to 125°C, and the storage time was set to one week. After one week of storage, the internal resistance (Ω) between the positive and negative electrodes of the button batteries of Example 1, Comparative Example 1, and Comparative Example 2 was measured in the same manner, and this value is shown in Table 1 below as the internal resistance (Ω) after one week of storage.

[0078] [Table 1]

[0079] Evaluation results As shown in Table 1, Example 1 (flange height 4mm) had an initial internal resistance of 3.461 Ω, clearly demonstrating the superiority of the initial internal resistance of the button battery compared to Comparative Example 1 (flange height 10mm). Analysis of the battery after disassembly revealed that the initial internal resistance of Comparative Example 1 was significantly higher than that of Example 1 because, after the flange of pad 20 was fitted into positive electrode sheet 15, the flange of pad 20 deformed, causing the positive electrode sheet 15 to fall off, resulting in poor internal contact and resulting in a significantly higher initial internal resistance than that of Example 1.

[0080] When comparing Example 1 (flange height: 4t) and Comparative Example 2 (flange height: 2t), the difference in the initial internal resistance of the button battery is not large; however, after storing the button battery at 125°C for one week, the rate of increase in the internal resistance of the button battery of Comparative Example 2 is much higher than the rate of increase in the internal resistance of the button battery of Example 1. When images of the button battery were taken and analyzed using CT, it was found that the flange portion of the pad 20 of the button battery of Comparative Example 2 had detached from the positive electrode sheet 15, and furthermore, the internal contact of the battery had become poor when stored at high temperatures.

[0081] Example 2 In the related art, a button battery mainly comprises a positive electrode cap, a negative electrode cap, a sealing ring, a positive electrode sheet, a negative electrode sheet, a positive electrode current collector, a separator, and an electrolyte. In consideration of the manufacturing process and assembly costs, the positive electrode current collector is usually configured as a sheet, mesh, or ring structure. In the battery assembly process, the positive electrode sheet and the positive electrode current collector are assembled to form a positive electrode assembly, which is placed in the inner chamber of the battery and packaged inside the battery using a mold.

[0082] Because the positive electrode assembly is fixed in the battery's inner chamber by the pressure of the mold package, this single fixing method results in low reliability of the positive electrode assembly's fixation inside the battery. In particular, in button batteries, under high-speed centrifugation and high-temperature conditions, the positive electrode assembly is prone to severe shaking and displacement, and further separation between the positive electrode assembly and the positive electrode cover becomes severe, causing problems such as collisions between the positive electrode sheet and the electrolyte, which further affect the stability of battery performance and prevent the battery from meeting the requirements of harsh application environments.

[0083] For example, when a battery is subjected to high-temperature conditions of 150°C, gas generation from the electrolyte increases the internal pressure of the battery, causing the positive and negative electrode covers to deform and expand, and a gap to form between the positive electrode cover and the positive electrode sheet, increasing the internal resistance of the battery and resulting in unacceptable battery performance.When the battery is subjected to high-speed centrifugal force of 3300g, the positive electrode assembly is placed directly inside the positive electrode cover, and there is no fixed or positional restriction between the current collecting ring / positive electrode current collector / current collecting sheet and the positive electrode cover, so the positive electrode assembly is prone to moving inside the battery, causing collisions between the positive electrode assembly and the electrolyte, further reducing the stability of the electrical performance of the button battery and ultimately causing the button battery to fail.

[0084] As an energy source, a button battery is fundamentally required to provide stable power supply at temperatures between -40°C and 85°C. High internal resistance of a battery can cause problems such as a shortened operating time, reduced battery capacity, accelerated self-discharge rate, voltage drop, and battery self-heating. Therefore, the internal resistance of a battery is used as an important indicator for evaluating the reliability and stability of a button battery. Typically, a button battery is required to have an initial internal resistance of less than 10 Ω and an internal resistance of less than 20 Ω after storage at 85°C for one week.

[0085] With the development of society and changes in the market, the application environment of button batteries is becoming increasingly worse, for example, button batteries are required to stably supply power under conditions of high temperature, high humidity, high pressure, high frequency vibration, and high speed centrifugal force. Tests have shown that when the temperature of the button battery application scene rises from 85°C to 125°C, in the button battery structure of the related art, the positive electrode cover will bulge outward severely with the temperature rise, the gap between the positive electrode cover and the positive electrode current collector will increase, the current collecting effect of the positive electrode current collector will be reduced, and the internal resistance of the button battery will increase sharply, and the button battery will not be able to meet the requirements of current application scenes.

[0086] With increasing market demand for use under high-speed centrifugal conditions, there is a demand for button batteries to be able to operate normally even under the action of a high-speed centrifugal force of 3300 g. However, the positive electrode assembly in the related art moves and shifts under high-speed centrifugation at 3300 g, and there is no elastic contact, which increases the internal resistance of the button battery and makes the electrical performance of the button battery unstable, so that the button battery cannot meet the requirements of current application scenarios.

[0087] In order for the button battery to maintain the stability of its electrical performance in extreme application scenarios, the present invention optimizes the internal structure of the button battery.

[0088] As shown in FIGS. 21 to 24, Example 2 of the present invention provides a button battery 1, which includes a positive electrode cover 11, a negative electrode cover 12, a seal ring 13, a positive electrode current collector 14, a positive electrode sheet 15, a negative electrode sheet 16, a separator 17, and an electrolyte.

[0089] The positive electrode cover 11 is configured as an open lid-like structure, and as shown in Figures 21 and 22, the outer surface of the positive electrode cover 11 may be configured as an upright surface structure, or as shown in Figures 23 and 24, a boss structure may be provided on the outer surface of the positive electrode cover 11.

[0090] The negative electrode lid 12 is configured as an open lid-shaped structure, and the inner and outer diameters of the positive electrode lid 11 are both larger than the inner and outer diameters of the negative electrode lid 12, thereby allowing the positive electrode lid 11 to cover the outside of the negative electrode lid 12.

[0091] The seal ring 13 is provided at the connection point between the positive electrode cover 11 and the negative electrode cover 12, and is configured to enclose at least a portion of the wall of the negative electrode cover 12 so as to form a sealed connection structure between the positive electrode cover 11 and the negative electrode cover 12. At the same time, the seal ring 13 functions to insulate the positive electrode cover 11 and the negative electrode cover 12 from each other.

[0092] The positive electrode current collector 14 includes an annular bottom wall 141 and a side wall 143 circumferentially connected to the top of the annular bottom wall 141, and the annular bottom wall 141 and the side wall 143 surround and define a storage chamber 144. The annular bottom wall 141 is provided with a through-hole 142. The outer diameter of the positive electrode current collector 14 is smaller than the inner diameter of the negative electrode cover 12.

[0093] The positive electrode sheet 15 is accommodated in the accommodation chamber 144 of the positive electrode current collector 14 and contacts the positive electrode cover 11 through the through-hole 142. During the assembly of the button battery, the positive electrode sheet 15 is placed inside the positive electrode current collector 14 to form a positive electrode assembly 100.

[0094] The negative electrode sheet 16 is housed within the interior of the negative electrode lid 12 , and during the battery assembly process, the negative electrode sheet 16 is placed inside the negative electrode lid 12 to form the negative electrode assembly 500 .

[0095] The separator 17 is provided between the positive electrode sheet 15 and the negative electrode sheet 16, separating the positive electrode sheet 15 and the negative electrode sheet 16, and the projection surface of the negative electrode sheet 16 onto the separator 17 roughly coincides with the projection surface of the positive electrode sheet 15 onto the separator 17.

[0096] The electrolyte is filled inside the button battery 1, and after the electrolyte is injected, the internal structure, such as the negative electrode sheet and positive electrode sheet, is immersed in the electrolyte, and the charged ions in the positive electrode sheet and negative electrode sheet communicate with each other through the electrolyte.

[0097] 21, 22, and 25, the button battery 1 further includes a pad 20. The pad 20 includes a pad portion 21 and an elastic sheet portion 22 that are connected to each other, and the pad portion 21 and the elastic sheet portion 22 are provided separately. The length of the pad portion 21 is set to L1, and the length of the elastic sheet portion 22 is set to L2, where L1>L2. The pad portion 21 and the elastic sheet portion 22 are connected to each other crosswise, and both ends of the pad portion 21 are connected to the positive electrode current collector. The pad 20 further includes protrusion structures 23 that pass through through-holes in the positive electrode current collector and are fixed to the positive electrode sheet 15. The protrusion structures 23 may be provided on the pad portion 21, the elastic sheet portion 22, or both the elastic sheet portion 22 and the pad portion 21. In the button battery, the positive electrode sheet 15 is configured as a compacted powder structure, and the protrusion structures 23 can be directly fitted into the positive electrode sheet 15.

[0098] A pad 20 is added to the button battery 1, and the pad 20 is connected to the positive electrode cover 11. The pad 20 has a pad portion 21 and an elastic sheet portion 22 that are connected to each other and cross each other. The length L1 of the pad portion 21 is greater than the length L2 of the elastic sheet portion 22. Both ends of the pad portion 21 are connected to the positive electrode current collector 14. The elastic sheet portion 22 is located within the positive electrode current collector 14. A protrusion structure 23 provided on either or both of the pad portion 21 and the elastic sheet portion 22 is further fixed within the positive electrode piece 15. Therefore, when the positive electrode cover 11 bulges outward, the pad 20 can further maintain contact between the positive electrode cover 11 and the positive electrode piece 15 and the positive electrode current collector 14, thereby improving the stability of the internal structure of the button battery 1.

[0099] 21 , 25 , 26 a, and 27 a, the pad unit 21 includes a pad base 211 and a pad boss 212 protruding from the pad base 211. The pad boss 212 and the pad base 211 define a pad receiving chamber 213, which is configured to receive a portion of the elastic sheet unit 22, thereby forming a stable connection structure between the elastic sheet unit 22 and the pad unit 21. If the elastic sheet unit 22 were directly connected to the pad base 211 of the pad unit 21, the elastic sheet base 221 would protrude from the pad base 211. Therefore, when the pad unit 21 is connected to the positive electrode current collector 14, the elastic sheet unit 22 located inside the current collector 14 would need to be entirely fitted into the positive electrode sheet 15, which can be seen to significantly increase the difficulty of assembling the pad 20 and the positive electrode assembly 100. Therefore, the pad portion 21 is provided with a pad boss 212 that protrudes from its pad base 211, and the pad boss 212 and the pad base 211 define a pad accommodating chamber 213. By placing the elastic sheet portion 22 within the pad accommodating chamber 213, the pad base 211 and the elastic sheet base 221 can be positioned in the same plane, which significantly reduces the difficulty of assembling the pad 20 and the positive electrode assembly 100.

[0100] In another alternative example, as shown in FIG. 27d, the elastic sheet portion 22 includes an elastic sheet base 221 and an elastic sheet boss 223 protruding with respect to the elastic sheet base 221. An elastic sheet accommodation chamber 224 is formed by the elastic sheet boss 223 and the elastic sheet base, and the elastic sheet accommodation chamber 224 is configured to accommodate a part of the pad portion 21.

[0101] Continuing to refer to FIGS. 26a, 26b, 26c, 27a, 27b, and 27c, the thickness of the elastic sheet portion 22 is set to t1, the height of the pad boss 212 is set to H1, H1≧t1, the width of the elastic sheet portion 22 is set to w1, the width of the pad boss 212 is set to w2, and w2 = (1.05 to 1.3) * w1.

[0102] The inventor has discovered through research that when the height H1 of the pad boss 212 and the thickness t1 of the elastic sheet portion 22 satisfy H1≧t1, the elastic sheet portion 22 can be completely accommodated in the pad accommodation chamber 213 defined by the pad boss 212 along its thickness direction. When the height H1 of the pad boss 212 and the thickness t1 of the elastic sheet portion 22 satisfy H1 < t1, at least a part of the elastic sheet portion 22 will protrude with respect to the pad base 211 of the pad portion 21 along its thickness direction, and the space inside the button-type battery 1 occupied by the pad 20 will increase.

[0103] The inventors have found that when the width w2 of the pad boss 212 and the width w1 of the elastic sheet portion 22 satisfy the relationship w2 = (1.05 to 1.3) * w1, the elastic sheet portion 22 can be completely accommodated in the pad receiving chamber 213 defined by the pad boss 212 along its width direction, and a sufficient margin for attachment can be formed between the elastic sheet portion 22 and the pad boss 212. If the width w2 of the pad boss 212 is w2 < 1.05w1, when the elastic sheet portion 22 and the pad portion 21 are both made of a hard material, a portion of the elastic sheet portion 22 cannot be assembled into the pad receiving chamber 213 defined by the pad boss 212. If the width w2 of the pad boss 212 is w2 > 1.3w1, the attachment gap between the elastic sheet portion 22 and the pad boss 212 is too large, resulting in wasted internal space in the button battery 1.

[0104] Similarly, an elastic sheet boss 223 is provided on the elastic sheet portion 22, and an elastic sheet accommodating chamber 224 is defined between the elastic sheet boss 223 and the elastic sheet base 221. When a portion of the pad portion 21 is accommodated in the elastic sheet accommodating chamber 224, the thickness of the pad portion 21 is set to t2, the height of the elastic sheet boss 223 is equal to or greater than the thickness t2 of the pad portion 21, the width of the pad portion 21 is set to w3, and the range of the ratio of the width of the elastic sheet boss 223 to the width of the pad is (1.05 to 1.3).

[0105] If the height of the elastic sheet boss 223 and the thickness t2 of the pad portion 21 do not meet the above dimensional requirements, at least a portion of the pad portion 21 will be installed protruding from the elastic sheet base 221 of the elastic sheet portion 22 along its thickness direction, and the space inside the button battery 1 occupied by the pad 20 will increase.

[0106] If the dimensional ratio between the height of the elastic sheet boss 223 and the width w3 of the pad portion 21 is not within the range of 1.05 to 1.3, the pad cannot be assembled into the elastic sheet accommodating chamber 224 defined by the elastic sheet boss 223, or the assembly gap between the pad and the elastic sheet boss 223 will be too large, resulting in wasted internal space of the button battery 1.

[0107] 27c, the thickness t1 of the elastic sheet portion 22 satisfies the relationship 0.05 mm≦t1≦0.30 mm. In a specific implementation, the thickness t1 of the elastic sheet portion 22 may be 0.05 mm, 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, or any two of the above values, or any range between the two values. The inventors discovered through research that if the thickness t1 of the elastic sheet portion 22 is less than 0.05 mm, the overall strength of the elastic sheet portion 22 is insufficient, and the elastic sheet portion 22 cannot be stably fitted into the positive electrode sheet. If the thickness t1 of the elastic sheet portion 22 is greater than 0.30 mm, the overall size of the elastic sheet portion 22 becomes large, and the pad 20 occupies a large amount of the internal space of the button battery. Through further research, the inventors have found that in some embodiments, by setting the thickness t1 of the elastic sheet portion 22 to 0.10 mm to 0.20 mm, the elastic sheet portion 22 can be optimized to simultaneously satisfy both strength and size ratio.

[0108] Continuing to refer to FIG. 26c, the thickness t2 of the pad portion 21 satisfies the relationship 0.05 mm≦t2≦0.30 mm. In a specific implementation, the thickness t2 of the pad portion 21 may be 0.05 mm, 0.1 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 numerical range between any two of the above values. The inventors' research revealed that if the thickness t2 of the pad portion 21 is less than 0.05 mm, the pad portion 21 lacks overall strength and is not stably fitted into the positive electrode sheet. If the thickness t2 of the pad portion 21 is greater than 0.30 mm, the overall size of the pad portion 21 increases, resulting in the pad assembly occupying a large amount of internal space in the button battery. Through further research, the inventors found that in some embodiments, the pad portion 21 can be optimized to simultaneously satisfy both strength and size ratios by setting the thickness t2 of the pad portion 21 to 0.10 mm to 0.20 mm.

[0109] The thickness t2 of the pad portion 21 and the thickness t1 of the elastic sheet portion 22 may be different as long as they are within a predetermined dimensional range. Further research has revealed that in some embodiments, by setting the thickness t2 of the pad portion 21 and the thickness t1 of the elastic sheet portion 22 to be the same, the strength of each part of the pad 20 formed by connecting the pad portion 21 and the elastic sheet portion 22 becomes the same, which is advantageous for the entire pad 20 to stably connect the positive electrode assembly and the positive electrode cover.

[0110] Suitable materials for manufacturing the pad portion 21 or the elastic sheet portion 22 include stainless steel, including at least one of SUS44, SUS304, SUS430, SUS316, and SUS444. The pad portion 21 and the elastic sheet portion 22 may be manufactured from different stainless steel materials with similar properties. In some embodiments, the pad portion 21 and the elastic sheet portion 22 are both manufactured from SUS430, making the pad portion 21 and the elastic sheet portion 22 magnetic. This facilitates welding between the pad portion 21 and the elastic sheet portion 22, reduces welding difficulty, and improves welding stability. Furthermore, if the pad portion 21 and the elastic sheet portion 22 are manufactured from the same stainless steel, it is advantageous to maintain a potential difference between the pad portion 21 and the elastic sheet portion 22.

[0111] Referring to FIG. 28, the elastic sheet portion 22 is welded to the pad portion 21 to form the pad 20, and the number of second welding points 241 between the elastic sheet portion 22 and the pad portion 21 is an even number, for example, the number of second welding points 241 may be two, four, six or eight, and in some embodiments, the number of second welding points 241 is set to two.

[0112] The inventors have found through research that if the number of second welding points 241 between the elastic sheet portion 22 and the pad portion 21 is one or an odd number greater than one, the welding between the elastic sheet portion 22 and the pad portion 21 is not strong and a relative misalignment occurs between the elastic sheet portion 22 and the pad portion 21. Using three-point or four-point welding between the elastic sheet portion 22 and the pad portion 21 further increases the cost of the welding process and is detrimental to improving production efficiency. Therefore, in a specific implementation, the number of welding points between the elastic piece portion 22 and the pad portion 21 is set to two.

[0113] 28, the welding area formed between the elastic sheet portion 22 and the pad portion 21 is a circular welding area Q5, the distance between the two second welding points 241 is the diameter of the circular welding area Q5, and the center of the circular welding area Q5 overlaps with the center of the pad 20. The diameter of the circular welding area Q5 is equal to or less than the width w1 of the elastic sheet portion 22 and is smaller than the width w3 of the pad portion 21.

[0114] Here, the elastic sheet portion 22 and the pad portion 21 form a circular welding area Q5, and the center of the circular welding area Q5 overlaps with the center of the pad 20, thereby forming a stable weld between the elastic sheet portion 22 and the pad portion 21 and being advantageous for forming a point-symmetric structure of the pad 20.

[0115] By setting the diameter of the circular welding area Q5 to be equal to or less than the width w1 of the elastic sheet portion 22 and the width w3 of the pad portion 21, the circular welding area Q5 is basically located in the central intersection area between the elastic sheet portion 22 and the pad portion 21, and after the elastic sheet portion 22 and the pad portion 21 are welded, the elastic sheet portion 22 and the pad portion 21 do not become asymmetric with respect to the center of the pad 20.

[0116] 22, 25, 27a and 30, the protrusion structure 23 comprises a first flange 231 and a second flange 232 provided on the elastic sheet portion 22, the first flange 231 being located at one end of the elastic sheet portion 22 and the second flange 232 being located at the other end of the elastic sheet portion 22.

[0117] The first flange 231 and the second flange 232 are fitted into the positive electrode sheet 15, and therefore the distance between the first flange 231 and the second flange 232 is configured to be within an effective range in which the entire pad 20 can restrict the positive electrode sheet 15. When the first flange 231 and the second flange 232 are positioned at an intermediate position of the elastic sheet portion 22, the effective range of the first flange 231 and the second flange 232 with respect to the positive electrode sheet 15 becomes smaller, and the restricting effect of the pad 20 on the positive electrode sheet 15 becomes weaker.

[0118] Continuing to refer to FIG. 27c, the first flange 231 and the second flange 232 are arranged symmetrically with respect to the center of the pad 20, and the protruding heights of the first flange 231 and the second flange 232 relative to the elastic sheet base 221 are the same and both are set to h1, and in some embodiments, the height h1 of the first flange 231 or the second flange 232 and the thickness t1 of the elastic sheet portion 22 satisfy 2*t1≦h1≦10*t1.

[0119] In some examples, h1 can be 2t1, 3t1, 4t1, 5t1, 6t1, 7t1, 8t1, 9t1, 10t1, and a number between any two of the above numbers, or a numerical range between any two of the above numbers.

[0120] Through research, the inventors have discovered that if the height h1 of the first flange 231 or the height h1 of the second flange 232 satisfies 2t1≦h1≦10t1, after the first flange 231 and the second flange 232 are fitted into the positive electrode sheet 15, the entire positive electrode sheet 15 will not be damaged by the first flange 231 or the second flange 232, causing the sheet to break or fall off, and the first flange 231 and the second flange 232 will not be deformed during the process of being fitted into the positive electrode sheet 15.

[0121] Referring to FIG. 30a, when the height h1 of the first flange 231 or the height h1 of the second flange 232 is less than 2t, the depth to which the first flange 231 or the second flange 232 is fitted into the positive electrode sheet 15 is insufficient, and when the positive electrode cover 11 bulges outward, the first flange 231 or the second flange 232 is likely to detach from the positive electrode sheet 15, causing poor contact of the entire pad 20 with the positive electrode current collector 14.

[0122] Referring to FIG. 30b, if the height h1 of the first flange 231 or the height h1 of the second flange 232 is greater than 10t1, the depth to which the first flange 231 and the second flange 232 are fitted into the positive electrode sheet 15 becomes greater, and in the process of fitting the first flange 231 or the second flange 232 into the positive electrode sheet 15, the pad 20 is likely to deform and the entire positive electrode sheet 15 is likely to be damaged.

[0123] Continuing to refer to FIG. 29a, the angle formed by the extension line of the outer cut surface of the first flange 231 or the second flange 232 and the plane on which the elastic seat base 221 is located is the same, and both are set to θ1, where θ1 satisfies 90°≦θ1≦150°.

[0124] In a specific implementation, the first flange 231 or the second flange 232 is arranged symmetrically with respect to the center of the pad 20, and the angle between the extension line of the outer cut surface of the first flange 231 and the plane on which the elastic seat base 221 is located is the same as the angle between the extension line of the outer cut surface of the second flange 232 and the plane on which the elastic seat base 221 is located, and both are set at θ1, where θ1 must satisfy 90°≦θ1≦150°. For example, θ1 may be 90°, 100°, 110°, 120°, 130°, 140°, 150°, and an angle between any two of the above angles, or a numerical range between any two of the above angles.

[0125] Through research, the inventors discovered that if θ1<90°, it is difficult for the first flange 231 or the second flange 232 to be fitted into the positive electrode sheet 15, and if θ1>150°, the range over which the first flange 231 or the second flange 232 is fitted into the positive electrode sheet 15 is too large, making the entire positive electrode sheet 15 prone to damage and causing powder to fall off.

[0126] Continuing to refer to Fig. 29a, the first flange 231 or the second flange 232 may be configured as a linear inclined structure. Alternatively, as shown in Fig. 9b, the first flange 231 or the second flange 232 may be configured as a wavy inclined structure. Alternatively, as shown in Fig. 9c, the first flange 231 or the second flange 232 may be configured as an inclined structure having a pointed end.

[0127] 21 and 26a, the protrusion structure 23 further includes a pad boss 212 provided on the pad portion 21, and the pad boss 212 is fitted into the positive electrode sheet 15 through the through hole 142. The pad boss 212 is located at approximately the center of the pad base 211, and is provided to protrude from the plane on which the pad base 211 is located, and defines a pad accommodating chamber 213 that accommodates at least a portion of the elastic sheet portion 22. The pad boss 212 is fitted into the positive electrode sheet 15 and functions to fix the positive electrode sheet 15.

[0128] The pad portion 21 and the elastic sheet portion 22 are welded together to form the pad 20, and the pad boss 212 forms a reinforcing rib-like structure in the elastic sheet portion 22, providing high strength after the pad boss 212 is fitted into the positive electrode sheet 15. The pad boss 212 and the elastic sheet portion 22 are combined to form a protruding structure with high fitting strength, allowing the protruding structure to make strong contact with the positive electrode sheet 15. Therefore, even if the positive electrode cover 11 bulges outward, separation between the positive electrode cover 11 and the positive electrode sheet 15, which would otherwise cause poor contact, is unlikely to occur.

[0129] Furthermore, when the pad portion 21 and the elastic sheet portion 22 are configured as an integral structure, the strength of the pad boss 212 is low, which is equivalent to the pad accommodating chamber 213 defined by the pad boss 212 not accommodating an elastic sheet, and therefore, if the height H1 of the pad boss 212 is high, the pad boss 212 is likely to be fitted into the positive electrode sheet 15 and deformed. If the height H1 of the pad boss 212 is small, the strength of the pad boss 212 can be improved, but the pad boss 212 cannot be fitted into the positive electrode sheet 15, or the depth at which the pad boss 212 is fitted into the positive electrode sheet 15 is insufficient, and an effective fixing effect cannot be achieved.

[0130] 31, the orthogonal projection of the pad 20 onto the positive electrode cover 11 is set to a cross shape, and the orthogonal projections of the pad portion 21 and the elastic sheet portion 22 onto the positive electrode cover 11 are both set to a line shape. The pad 20 and the positive electrode cover 11 are both configured to have a point-symmetric structure, and the center of the pad 20 almost overlaps with the center of the positive electrode cover 11.

[0131] By configuring the pad 20 in a cross-shaped structure so that the orthogonal projections of the pad portion 21 and the elastic sheet portion 22 on the positive electrode cover 11 are both set to a straight line shape, it is advantageous that both ends of the long pad portion 21 of the pad 20 are connected to the positive electrode current collector 14 and the short elastic sheet portion 22 of the pad 20 is located inside the positive electrode current collector 14.

[0132] The cross-shaped structure of the pad 20 may be a regular cross-shaped structure as shown in FIG. 31, or an irregular cross-shaped structure in which both ends of the pad portion 21 are configured as arc-shaped structures as shown in FIG. 32a, or the pad base 211 may have two pad base 211 portions located on either side of the pad boss 212 and both configured as fan-shaped structures as shown in FIG. 32b.

[0133] 31, 33 and 34, the pad 20 is welded to the positive electrode lid 11, the pad 20 and the positive electrode lid 11 are both configured to have a point-symmetric structure, and the concentricity between the pad 20 and the positive electrode lid 11 is 0.3 mm or less.

[0134] During the welding process between the pad 20 and the positive electrode cover 11, the concentricity between the pad 20 and the positive electrode cover 11 needs to be controlled to 0.3 mm or less. In some embodiments, the concentricity between the pad 20 and the positive electrode cover 11 is 0.1 mm or less. The inventors have found through research that if the concentricity between the positive electrode cover 11 and the pad 20 exceeds 0.3 mm, the misalignment between the pad 20 and the positive electrode cover 11 will be severe, which will further severely misalign the pad 20 and the current collector 14, thereby reducing the current collecting effect of the positive electrode current collector 14 and further affecting the electrical performance of the button battery 1.

[0135] Continuing to refer to FIG. 31, the number of third weld points 242 formed by welding the pad 20 and the positive electrode cover 11 is at least two, and the at least two third weld points 242 are provided symmetrically with respect to the center of the pad 20.

[0136] The inventors have found through research that when the number of third weld points 242 formed by welding the pad 20 to the positive electrode cover 11 is set to two in the process of welding the pad 20 to the positive electrode cover 11, the two third weld points 242 contribute to improving the welding strength between the pad 20 and the positive electrode cover 11. If the number of third weld points 242 formed by welding the pad 20 to the positive electrode cover 11 is one, the pad 20 is more likely to be misaligned and warped relative to the positive electrode cover 11, and if the number of third weld points 242 formed by welding the pad 20 to the positive electrode cover 11 exceeds two, the welding process between the pad 20 and the positive electrode cover 11 becomes more complicated and the welding costs increase.

[0137] Continuing to refer to FIGS. 31 and 35, by optimizing the position of the welding area between the pad 20 and the positive electrode cover 11, the stability performance of the button battery 1 can be further improved.

[0138] The weldable base of the pad 20 is divided into five regions, namely, a first region Q1, a second region first portion Q2a, a second region second portion Q2b, a third region first portion Q3a, and a third region second portion Q3b. The first region Q1 is the welding region between the pad portion 21 and the elastic sheet portion 22. The second region first portion Q2a and the second region second portion Q2b are located on both sides of the first region Q1 and are located in the pad portion 21. The third region first portion Q3a and the third region second portion Q3b are located on both sides of the first region Q1 and are located in the elastic sheet portion 22.

[0139] The position of the third welding point 242 between the pad 20 and the positive electrode cover 11 is provided in the first portion Q2a of the second region and the second portion Q2b of the second region, and is located outside the first portion Q3a of the third region and the second portion Q3b of the third region.

[0140] The inventors have found through research that if the third welding point 242 between the pad 20 and the positive electrode cover 11 is located in the first portion Q3a of the third region and the second portion Q3b of the third region, the elasticity of the first portion Q3a of the third region and the second portion Q3b of the third region where the pad 20 is located is lost, and if the positive electrode cover 11 expands, the first flange 231 and the second flange 232 of the pad 20 are welded to the positive electrode cover 11, so the first flange 231 and the second flange 232 are separated from the positive electrode sheet 15, further causing poor contact between the pad 20 and the positive electrode sheet 15 and invalidating the positional restriction effect of the first flange 231 and the second flange 232. Note that the first region Q1 is configured as a welding region between the pad portion 21 and the elastic sheet portion 22, and therefore the first region Q1 cannot be used as a welding region between the pad 20 and the positive electrode cover 11.

[0141] 27b, 31, and 35, the distance between the at least two third weld points 242 is set to d1, where d1 satisfies 0.3*L1+0.7*w1≦d1≦0.9*L1+0.1*w1, where L1 is set to the length of the pad portion 21, and w1 is set to the width of the spring portion 22.

[0142] The inventors have found that to ensure consistent performance after welding between the pad 20 and the positive electrode cover 11, two third welding points 242 are provided between the pad 20 and the positive electrode cover 11, and the two third welding points 242 are distributed symmetrically about the center of the pad 20. Furthermore, to ensure that the button battery can be used at high temperatures and to prevent a non-contact gap between the pad 20 and the positive electrode cover 11 from occurring when the positive electrode cover 11 bulges outward, the distance d1 between the two third welding points 242 is required to satisfy 0.3*L1+0.7*w1≦d1≦0.9*L1+0.1*w1, where L3=0.3*L1+0.7*w1, L4=0.9*L1+0.1*w1, and L3≦d1≦L4, as shown in Figures 35, 36a, and 36b. If the distance d1 between the two third welding points 242 is too large, i.e., if d1 is greater than 0.9*L1+0.1w1, the third welding point 242 is located on the edge close to the pad 20, the welding strength between the pad 20 and the positive electrode cover 11 is low, and if the positive electrode cover 11 bulges outward, the pad 20 and the positive electrode cover 11 are likely to separate, and the connection between the pad 20 and the positive electrode cover 11 will be lost. As shown in Figures 36a and 36b, if the distance d1 between the two third welding points 242 is too small, that is, if d1 is smaller than 0.3*L1+0.7*w1, the third welding point 242 will be located close to the center of the positive electrode cover 11. If the positive electrode cover 11 bulges outward, the pad 20 will bulge outward together with the positive electrode cover 11, making it easier for the pad 20 to separate from the positive electrode sheet 15. This will invalidate the positional restriction function of the pad 20 on the positive electrode sheet 15, resulting in poor contact between the positive electrode sheet 15 and the positive electrode cover 11.

[0143] 35, 37, and 38, the positive electrode current collector 14 has an annular bottom wall 141, which defines a through-hole 142, both ends of the pad portion 21 are connected to the annular bottom wall 141, both ends of the pad portion 21 are pressed between the annular bottom wall 141 and the positive electrode lid 11, and the positive electrode sheet 15 housed inside the positive electrode lid 11 comes into contact with the positive electrode lid 11 through the through-hole 142.

[0144] 37 to 41 and 42a, the diameter of the circumscribed circle corresponding to the edge of the pad portion 21 is set to D1, the diameter of the circumscribed circle corresponding to the edge of the elastic sheet portion 22 is set to D2, the pad portion 21 has a first end portion 2141 and a second end portion 2142 arranged opposite each other, the first end portion 2141 has two first end points 2143, the included angle between lines connecting each of the two first end points 2143 and the center of the pad 20 is 2θ2, the diameter of the through hole 142 of the positive electrode current collector 14 is set to D3, the outer diameter of the annular bottom wall 141 of the positive electrode current collector 14 is set to D4, the thickness of the positive electrode current collector 14 is set to t3, and the length L1 of the pad portion 21 satisfies L1=D1*cosθ2 and 1.02*D3*cosθ2≦L1≦0.98*(D4-2t3)*cosθ2.

[0145] In order to ensure that both ends of the pad portion 21 always contact the annular bottom wall 141 of the positive electrode current collector 14, and that both ends of the pad portion 21 still contact the annular bottom wall 141 of the positive electrode current collector 14 after the button battery 1 is sealed, the inventor has researched and found that in some embodiments, 1.02*D3*cosθ2≦L1≦0.98*(D4-2t3)*cosθ2.

[0146] Furthermore, as shown in FIG. 42b, when the length of the pad portion 21 is set to L1a and L1a>0.98*(D4-2t3)*cosθ2, at least a part of the region where one end of the pad portion 21 is located exceeds the region Q4 where the annular bottom wall 141 of the positive electrode current collector 14 is located, as in the excess region 21a shown in FIG. 42b, and the other end of the pad portion 21 does not contact the region Q4 where the annular bottom wall 141 is located, as in 41b shown in FIG. During the process of sealing the battery 1, the strength of the edge of the positive electrode current collector 14 is greater than the strength of the plane on which the annular bottom wall 141 of the positive electrode current collector 14 is located. Therefore, the height corresponding to the excess region 21a of the pad portion 21 that exceeds the edge of the positive electrode current collector 14 is greater than the height corresponding to the non-excess region 21b of the pad portion 21 that does not exceed the edge of the positive electrode current collector 14. This creates a step inside the positive electrode current collector 14, which reduces the current collection effect of the positive electrode current collector 14.

[0147] Furthermore, as shown in Figure 42c, when the length of the pad portion 21 is set to L1b and L1b<1.02*D3*cosθ2, the region where one end of the pad portion 21 is located, as in the excess region 41c shown in Figure 42c, is located in the region where the through hole 142 of the positive current collector 14 is located, and the other end of the pad portion 21 is located in the planar region Q4 where the annular bottom wall 141 of the positive current collector 14 is located, as in the non-excess region 21d shown in Figure 42c, during the process of sealing the button battery 1, the height of one end of the pad portion 21 corresponding to the excess region 21c where the through hole 142 of the positive current collector 14 is located is greater than the height of the other end of the pad portion 21 corresponding to the non-excess region 21d of the plane where the annular bottom wall 141 of the positive current collector 14 is located, resulting in a step inside the positive current collector 14 and reducing the current collecting effect of the positive current collector 14.

[0148] Continuing to refer to Figures 39 to 42, the elastic sheet portion 22 has a first elastic sheet end portion 2221 and a second elastic sheet end portion 2222, the first elastic sheet end portion 2221 has two elastic sheet end points 2223, the included angle between the lines connecting each of the two elastic sheet end points 2223 and the center of the pad 20 is 2θ3, and the length L2 of the elastic sheet portion 22 satisfies 1.5*w3≦L2≦0.98*D3*cosθ3, where w3 is the width of the pad portion 21 and D3 is the internal diameter of the through hole 142.

[0149] When the button battery 1 is packaged, the first flange 231 and the second flange 232 of the elastic sheet portion 22 are fitted into the positive electrode piece 15 to restrict the position of the positive electrode piece 15. Through research, the inventors have found that when there is a misalignment between the pad 20 and the positive electrode current collector 14, or when the positive electrode cover 11 bulges outward, the length L2 of the elastic sheet portion 22 must satisfy 1.5*w3≦L2≦0.98*D3*cosθ3 to ensure that the first flange 231 and the second flange 232 of the elastic sheet portion 22 are still fitted into the positive electrode piece 15 and maintain an elastic connection with the positive electrode piece 15.

[0150] If the length L2 of the elastic sheet portion 22 is greater than 0.98*D3*cosθ3, the relative positional deviation between the pad 20 and the positive electrode collector 14 is large, and either or both of the first flange 231 and the second flange 232 cannot be fitted into the positive electrode sheet 15. If the length L2 of the elastic sheet portion 22 is less than 1.5w3, when the positive electrode cover 11 bulges outward, either or both of the first flange 231 and the second flange 232 of the elastic sheet portion 22 move outward along with the positive electrode cover 11, and either or both of the first flange 231 and the second flange 232 detach from the positive electrode sheet 15. As a result, the pad 20 can no longer elastically restrict the positive electrode collector 14, and poor contact occurs between the pad 20 and the positive electrode collector 14.

[0151] The present invention further provides a manufacturing method for the pad 20 of the button cell 1. As shown in Figures 43a, 43b and 43c, the manufacturing method for the pad 20 includes: A pad set 400 is manufactured by a press molding process, in which a plurality of pads are connected to each other in a band shape, and adjacent pads are connected by connecting the edges of their materials as shown in FIG. 43a; By a press molding process, an elastic sheet set 300 is manufactured, which is formed into a band shape and is made up of a plurality of elastic sheets connected together, and as shown in FIG. 43b, adjacent elastic sheets are connected by connecting the edges of their materials; After adjusting the elastic sheet set 300 and the pad set 400 so that their centers are overlapped, the elastic sheet set 300 and the pad set 400 are welded together using laser welding equipment to form a plurality of connected pad assemblies, and adjacent pad assemblies are connected by connecting the edges of their materials, as shown in Figure 43c.

[0152] The above-described manufacturing method of the pad 20 can effectively improve the production efficiency of the pad 20 and reduce the cost of the assembly process compared to a manufacturing method in which a single pad and a single elastic sheet are welded together to form the pad 20.

[0153] An embodiment of the present invention further provides a method for assembling a button battery, the method comprising: Step 1: Cutting the connected body of the pad assembly to form a single pad assembly; Step 2: after adjusting the relative position between the pad assembly and the positive electrode cover, as shown in FIG. 44, welding the pad assembly and the positive electrode cover to form a positive electrode cover assembly; Step 3: placing the positive electrode sheet into a positive electrode current collector to form a positive electrode assembly; Step 4: placing the negative electrode sheet in the negative electrode cap to form a negative electrode cap assembly; Step 5: sequentially placing a separator and a positive electrode assembly in the negative electrode cap assembly to form a combination; Step 6: injecting an electrolyte into the assembly; and step 7 of capping the end of the assembly with a positive electrode cap module, sealing and transforming to form a button cell battery.

[0154] It should be noted that the order of the steps in the above manufacturing method can be adjusted according to the needs of the actual assembly process, and is not limited to the order described in the above embodiment.

[0155] In the present invention, a more specific example 2 and comparative examples 3 to 6 are provided, and high-temperature storage experiments are conducted on the button batteries 1 according to example 2 and comparative examples 3 to 6 to further verify the changes in the internal resistance of the batteries in high-temperature environments according to example 2, comparative example 3, comparative example 4, comparative example 5, and comparative example 6.

[0156] Example 2 Referring to Figure 44a, the button battery of Example 2 includes a pad 20, and as shown in Figure 25, the pad base and the elastic sheet base of the pad 20 are configured to have a straight structure, the length of the pad is L1 = 0.91 * (D4 - 2t3) * cos θ2, the length of the elastic sheet is L2 = 0.72 * D3 * cos θ3, the thickness t2 of the pad or the thickness t1 of the elastic sheet 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 = 4 * t1.

[0157] Comparative Example 3 Referring to Figure 44c, the button battery of Comparative Example 3 includes a pad 20, and as shown in Figure 25, the pad base and the elastic sheet base are both configured to adopt a straight structure, the length of the pad is L1 = 0.91 * (D4 - 2t3) * cos θ2, the length of the elastic sheet is L2 = 0.72 * D3 * cos θ3, the thickness t2 of the pad or the thickness t1 of the elastic sheet 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.

[0158] Comparative Example 4 Referring to Figure 44b, the button battery of Comparative Example 4 includes a pad 20, and the pad 20 is configured such that the pad base and the elastic sheet base both adopt a linear structure as shown in Figure 25, the length of the pad is L1 = 0.91 * (D4 - 2t1) * cos θ2, the length of the elastic sheet is L2 = 0.72 * D3 * cos θ3, the thickness t2 of the pad or the thickness t1 of the elastic sheet 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 = 2 * t1.

[0159] Comparative Example 5 The button battery of Comparative Example 5 includes a pad 20, and as shown in FIG. 25, the pad base and the elastic sheet base of the pad 20 are configured to have a straight structure, the length of the pad is L1=(D4-2t1)*cosθ2, the length of the elastic sheet is L2=0.72*D3*cosθ3, the thickness t2 of the pad or the thickness t1 of the elastic sheet 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=4*t1.

[0160] Comparative Example 6 The button battery of Comparative Example 6 includes a pad 20, and as shown in FIG. 25, the pad 20 is configured so that both the pad base and the elastic sheet base adopt a straight structure, the length of the pad is L1=0.90*D3*cosθ2, the length of the elastic sheet is L2=0.72*D3*cosθ3, the thickness t2 of the pad or the thickness t1 of the elastic sheet is t1=t2=0.10*t, the angle θ1 of the first flange or the second flange is θ1=120°, and the height h1 of the second flange satisfies h1=4*t1.

[0161] High temperature storage test (internal resistance evaluation) The button batteries of Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6 obtained by the above procedure were subjected to the high-temperature storage test described below, and the change in internal resistance under high-temperature conditions was evaluated.

[0162] Specifically, first, the internal resistance (Ω) between the positive and negative electrodes of the button batteries obtained in Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6 was measured in the same manner, and the initial resistance (Ω) is shown in Table 2 below. Next, the button batteries of Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6 were stored in a high-temperature box, the internal temperature of the high-temperature box was set to 125°C, and the storage time was set to one week. After one week of storage, the internal resistance (Ω) between the positive and negative electrodes of the button batteries of Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, and Comparative Example 6 was measured in the same manner, and this value is shown in Table 2 below as the internal resistance (Ω) after one week of storage.

[0163] [Table 2]

[0164] Evaluation results As shown in Table 2, comparing Example 2 and Comparative Example 3, the height h1 of the first or second flange of the pad of the button battery of Example 2 is set to 4t1, and the initial internal resistance is 3.259Ω. When the height h1 of the first or second flange of the pad of the button battery of Comparative Example 3 is set to 10t1, the initial internal resistance of the button battery of Example 2 is significantly higher than that of Comparative Example 3. After disassembling and analyzing the batteries, the initial internal resistance of the button battery of Comparative Example 3 was found to be much higher than that of Example 2 because, after the first or second flange of the button battery of Comparative Example 3 was fitted into the positive electrode sheet, the first or second flange of the button battery was deformed, causing the positive electrode sheet to fall off and resulting in poor internal contact. Consequently, the initial internal resistance of the button battery of Comparative Example 3 was much higher than that of the button battery of Example 1.

[0165] As shown in Table 2, comparing Example 2 and Comparative Example 4, when the height of the first or second flange of the pad of the button battery of Example 2 is set to h1 and 4t1, and the height of the first or second flange of the pad of the button battery of Comparative Example 4 is set to h1 and 2t1, the difference in initial internal resistance between the button battery of Example 2 and the button battery of Comparative Example 4 is not large. However, after high-temperature storage at 125°C for one week, the increase in internal resistance of the button battery of Comparative Example 4 is much higher than that of the button battery of Example 2. When images of the button battery were taken and analyzed using CT (computed tomography), it was found that a portion of the first or second flange of the pad assembly of the button battery of Comparative Example 4 detached from the positive electrode sheet, resulting in poor internal contact of the button battery during high-temperature storage.

[0166] As is clear from the results of the examples and comparative examples described above, by setting the height of the first flange or second flange on the pad of a button battery as the h1 parameter according to the conditions specified in the present invention, the internal contact of the battery can be increased, thereby achieving the goal of improving the stability of the battery. Furthermore, poor internal contact due to outward bulging of the positive electrode cover in high-temperature environments can be effectively prevented, so that the characteristics of the button battery do not deteriorate and the stability of the battery's electrical performance is improved.

[0167] Comparing Example 2 and Comparative Example 5, the pad length of the button battery of Example 2 was set to 0.91*(D4-2t1)*cosθ2, and the pad length of the button battery of Comparative Example 5 was set to (D4-2t1)*cosθ2. From the data in Table 2, it was found that when the pad length was too long, the initial internal resistance of the button battery of Comparative Example 5 was close to that of the button battery of Example 2. However, after high-temperature storage at 125°C for one week, the rate of increase in internal resistance of the button battery of Comparative Example 5 was much greater than that of the button battery of Example 2. Visual inspection of the button batteries of Comparative Example 5 and Example 2 revealed obvious dents and protrusions on the positive electrode cover of the button battery of Comparative Example 5. CT scanning of the button batteries of Comparative Example 5 and Example 2 revealed that the length of the pad exceeded the positive electrode current collector at the protrusion on the positive electrode cover of the button battery of Comparative Example 5. As can be seen from this analysis, after the length of a portion of the pad portion exceeds the positive electrode current collector, the pad portion and the positive electrode current collector form a reinforcing rib-like structure. Therefore, when the battery is sealed, the strength of different positions on the pad portion and the positive electrode current collector differs, causing the positive electrode cover of the battery to bulge outward, which makes the internal resistance of the battery unstable and increases after high-temperature storage.

[0168] Comparing Example 2 and Comparative Example 6, when the pad length of the button battery of Example 2 is set to 0.91*(D4-2t1)*cosθ2 and the pad length of the button battery of Comparative Example 6 is set to 0.90*D3*cosθ2, the data in Table 2 show that when the pad length is too short, the initial internal resistance of the button battery of Comparative Example 6 is close to that of the button battery of Example 2. However, after one week of high-temperature storage at 125°C, the increase in internal resistance of the button battery of Comparative Example 6 is as high as 216%, far greater than that of the button battery of Example 2. First, CT observation of the button battery of Comparative Example 6 revealed that one side of the pad was not located in region Q4 where the annular bottom wall of the positive electrode current collector was located, and a small gap existed between the pad and the positive electrode current collector at the outward bulge of the positive electrode cover. When the battery was disassembled, it was found that one side of the pad was not located in region Q4 where the annular bottom wall of the positive electrode current collector was located, and part of the pad was separated from the positive electrode sheet, causing further poor contact and increasing internal resistance. [Explanation of symbols]

[0169] 1. Button cell battery 11...Positive electrode cover 111...Boss structure 12...Negative electrode lid 13...Seal ring 14...Positive electrode current collector 141...Annular bottom wall 142...Through hole 143…Side wall 144…Containment room 15...Positive electrode sheet 16...Negative electrode sheet 17...Separator 19...Electrolyte 20...Pad 21...Pad section 211...Pad base 212...Pad boss 213...Pad Containment Room 214...Pad end 2141...First pad end 2142...Second pad end 2143...Pad end point 215...Pad side edge 22...Elastic sheet portion 221...Elastic seat base 222...Elastic sheet end 2221...First elastic sheet end 2222...Second elastic sheet end 2223...Elastic sheet end point 223...Elastic seat boss 224... Elastic sheet storage room 23…Protrusion structure 231...First flange 232...Second flange 233…protrusion 23a...Excess area 23b…Non-exceeding area 24...Base surface 25...Positioning hole 200...Pad assembly 210...First welding point 241...Second welding point 242...Third welding point 220...Positive electrode cover assembly Q1…First area Q2a…Second area 1st part Q2b…Second area second part Q3a…3rd area 1st part Q3b…3rd area 2nd part Q4: Annular bottom wall position area Q5...Circular welding area 100...Positive electrode assembly 500...Anode assembly 300...Elastic sheet set 400...Pad set

Claims

1. A button cell battery (1) comprising a positive electrode cap assembly (220), a positive electrode current collector (14), and a positive electrode sheet (15); The positive electrode cap assembly (220) comprises a positive electrode cap (11) and a pad (20) attached to the inside of the positive electrode cap (11); The positive electrode current collector (14) is provided inside the positive electrode cover (11), and a storage chamber (144) is provided therein. A through-hole (142) is provided in the bottom wall of the positive electrode current collector (14). The positive electrode sheet (15) is located in the storage chamber (144), The pad (20) comprises a pad portion (21) and an elastic sheet portion (22) that are arranged to intersect with each other, the pad portion (21) has a length L1, the elastic sheet portion (22) has a length L2, and L1>L2, and one or both of the elastic sheet portion (22) and the pad portion (21) are provided with a protrusion structure (23) that passes through the through hole (142) and is fixed to the positive electrode sheet (15). Button cell battery (1).

2. The pad portion (21), the elastic sheet portion (22), and the protrusion structure (23) are integrally molded, and the thickness of the pad (20) is t, where 0.05≦t≦0.30 mm. A button cell battery (1) according to claim 1.

3. The protrusion structure (23) comprises a first flange (231) and a second flange (232), and the first flange (231) and the second flange (232) are provided at both ends of the elastic sheet portion (22), respectively. A button cell battery (1) according to claim 1.

4. The height of the first flange (231) or the second flange (232) is defined as h1, and 2*t<h1<10*t; and / or The angle between an extension line of the outer cut surface of the first flange (231) or the second flange (232) and a plane on which the elastic sheet portion (22) is located is θ1, and θ1 is 90° to 150°. A button cell battery (1) according to claim 3.

5. The protrusion structure (23) comprises at least two protrusions (233) provided on the pad portion (21), the at least two protrusions (233) being provided symmetrically and located on both sides of the elastic sheet portion (22). A button cell battery (1) according to claim 1.

6. The height of the protrusion (233) is h2, and 1.5 * t ≦ h2 ≦ 3 * t. A button cell battery (1) according to claim 5.

7. The orthogonal projection of the pad (20) on the positive electrode cover (11) is configured as a cross, an octagonal cross, or a combination of a circle and a cross. A button cell battery (1) according to claim 1.

8. The pad (20) is provided with a positioning hole (25) configured to determine position when the pad (20) and the positive electrode cover (11) are welded together, and the pad (20) is welded to the positive electrode cover (11), and the concentricity between the pad (20) and the positive electrode cover (11) is 0.3 mm or less. A button cell battery (1) according to any one of claims 1 to 7.

9. There are two or more first welding points (210) between the pad (20) and the positive electrode cover (11), and the at least two first welding points (210) are provided symmetrically with respect to the center point of the pad (20). A button cell battery (1) according to claim 8.

10. the pad (20) comprises a first region (Q1), second regions (Q2a, Q2b) located in the pad portion, and third regions (Q3a, Q3b) located in the elastic sheet portion (22); the first region (Q1) is symmetrical with respect to the center line of the pad portion (21) and the center line of the elastic sheet portion (22); the second regions (Q2a, Q2b) comprise a second region first portion (Q2a) and a second region second portion (Q2b) located on both sides of the first region (Q1); the third regions (Q3a, Q3b) comprise a third region first portion (Q3a) and a third region second portion (Q3b) located on both sides of the first region (Q1); the length of the first region (Q1) is d1, where d1 = 0.5 * L1; the width of the first region (Q1) is equal to the width of the pad portion (21); At least two of the first welding points (210) are located within the first region (Q1), and / or at least two of the first welding points (210) are located within the second region first portion (Q2a) and the second region second portion (Q2b), and at least two of the first welding points (210) are located outside the third region first portion (Q3a) and the third region second portion (Q3b).

10. The button cell battery (1) according to claim 9.

11. The positive electrode current collector (14) has an annular bottom wall (141), and both ends of the pad portion (21) are connected to the annular bottom wall (141). A button cell battery (1) according to any one of claims 1 to 7.

12. The diameter of a circumscribed circle corresponding to the edge of the pad portion (21) is D1, the pad portion (21) has two pad end portions (214), one of which has two pad end points (2143), the included angle between lines connecting each of the two pad end points (2143) and the center of the pad (20) is 2*θ2, the diameter of the through hole (142) of the positive electrode current collector (14) is D3, the diameter of the annular bottom wall (141) of the positive electrode current collector (14) is D4, the thickness of the positive electrode current collector (14) is t3, and the length L1 of the pad portion satisfies L1=D1*cos θ2 and 1.02*D3*cos θ2≦L1≦0.98*(D4-2*t3)*cos θ2. A button cell (1) according to claim 11.

13. The pad portion (21) has two pad side edges (215) that are provided opposite to each other, and the pad end portion (214) is provided so as to protrude from the pad side edges (215), or the pad end portion (214) is provided so as to be flush with the pad side edges (215).

13. The button cell battery (1) according to claim 12.

14. The width of the pad portion (21) is w3, the diameter of the through hole (142) of the positive electrode current collector (14) is D3, the elastic sheet portion (22) has two elastic sheet end portions (222), one of which has two elastic sheet end points (2223), the included angle between lines connecting each of the two elastic sheet end points (2223) and the center of the pad (20) is 2*θ3, and the length L2 of the elastic sheet portion satisfies 1.5*w3≦L2≦0.98*D3*cosθ3.

13. The button cell battery (1) according to claim 12.

15. The pad portion (21) and the elastic sheet portion (22) are molded separately, and the protrusion structure (23) is molded integrally with the pad portion (21) or the elastic sheet portion (22). A button cell battery (1) according to claim 1.

16. The pad portion (21) comprises a pad base (211) and a pad boss (212) protruding from the pad base (211), and the pad boss (212) and the pad base (211) define a pad accommodating chamber (213) configured to accommodate a portion of the elastic sheet portion (22), or The elastic sheet portion (22) comprises an elastic sheet base (221) and an elastic sheet boss (223) protruding from the elastic sheet base (221), and the elastic sheet boss (223) and the elastic sheet base (221) define an elastic sheet accommodating chamber (224) configured to accommodate a portion of the pad portion (21).

16. The button cell battery (1) according to claim 15.

17. the thickness of the elastic sheet portion (22) is t1, the height of the pad boss (212) is H1, the height H1 of the pad boss (212) is equal to or greater than the thickness t1 of the elastic sheet portion (22), and / or the width of the elastic sheet portion (22) is w1, the width of the pad boss (212) is w2, and the ratio of the width w2 of the pad boss (212) to the width w1 of the elastic sheet portion (22) is (1.05 to 1.3):1; Alternatively, the thickness of the pad portion (21) is t2, the height of the elastic sheet boss (223) is equal to or greater than the thickness t2 of the pad portion (21), and / or the width of the pad portion (21) is w3, and the ratio of the width of the elastic sheet boss (223) to the width w3 of the pad portion (21) is (1.05 to 1.3):

1.

17. The button cell battery (1) according to claim 16.

18. The thickness t1 of the elastic sheet portion (22) satisfies 0.05 mm≦t1≦0.30 mm, and / or The thickness t2 of the pad portion (21) satisfies 0.05≦t2≦0.30 mm, and / or The thickness t1 of the elastic sheet portion (22) and the thickness t2 of the pad portion (21) are the same.

18. The button cell battery (1) according to claim 17.

19. The elastic sheet portion (22) is welded to the pad portion (21), and the number of second welding points (241) between the elastic sheet portion (22) and the pad portion (21) is an even number.

18. The button cell battery (1) according to claim 17.

20. The elastic sheet portion (22) is welded to the pad portion (21) within a circular welding region (Q5), and the diameter of the circular welding region (Q5) is smaller than the width w1 of the elastic sheet portion (22) and smaller than the width w3 of the pad portion.

20. The button cell battery (1) according to claim 19.

21. The protrusion structure (23) comprises a first flange (231) and a second flange (232) provided on the elastic sheet portion (22), the first flange (231) being located at one end of the elastic sheet portion (22), and the second flange (232) being located at the other end of the elastic sheet portion (22), and the first flange (231) and the second flange (232) being fitted into the positive electrode sheet (15) through the through hole (142).

18. The button cell battery (1) according to claim 17.

22. The height of the first flange (231) or the second flange (232) is defined as h1, and 2*t1<h1<10*t1; and / or The angle between the extension line of the outer cut surface of the first flange (231) or the second flange (232) and the plane on which the elastic seat base (221) is located is θ1, and θ1 is 90° to 150°; 22. The button cell battery (1) according to claim 21.

23. The protrusion structure (23) further includes the pad boss (212) that passes through the through hole (142) and is fitted into the positive electrode sheet (15).

22. The button cell battery (1) according to claim 21.

24. The orthogonal projection of the pad (20) on the positive electrode cover (11) is a cross, and the orthogonal projections of the elastic sheet portion (22) and the pad portion (21) on the positive electrode cover (11) are both linear. A button cell (1) according to any one of claims 15 to 23.

25. The elastic sheet portion (22) and the pad portion (21) are made of the same stainless steel material.

25. The button cell battery (1) according to claim 24.

26. The pad (20) is welded to the positive electrode cover (11), the pad (20) and the end point of the elastic sheet (11) are configured to have a point-symmetric structure, and the concentricity between the pad (20) and the positive electrode cover (11) is 0.3 mm or less.

17. The button cell battery (1) according to claim 16.

27. At least two third welding points (242) are provided between the pad (20) and the positive electrode cover (11), and the at least two third welding points (242) are provided symmetrically with respect to the center of the pad (20).

27. The button cell battery (1) according to claim 26.

28. The pad (20) comprises a first region (Q1) formed by welding the pad portion (21) and the elastic sheet portion (22), a second region (Q2a, Q2b) located in the pad portion (21), and a third region (Q3a, Q3b) located in the elastic sheet portion (22), the second region (Q2a, Q2b) comprising a second region first portion (Q2a) and a second region second portion (Q2b) located on first opposite sides of the first region (Q1) that face each other, and the third region (Q3a, Q3b) comprising a third region first portion (Q3a) and a third region second portion (Q3b) located on second opposite sides of the first region (Q1) that face each other, At least two of the third welding points (242) are located within the second region first portion (Q2a) and the second region second portion (Q2b), and are located outside the third region first portion (Q3a) and the third region second portion (Q3b).

28. Button cell battery (1) according to claim 27.

29. The distance between at least two of the third weld points (242) is d1, and 0.3*L1+0.7*w1≦d1≦0.9*L1+0.1*w1.

29. The button cell battery (1) according to claim 28.

30. The positive electrode current collector (14) has an annular bottom wall (141) to which both ends of the pad portion (21) are connected.

16. The button cell battery (1) according to claim 15.

31. The diameter of a circumscribed circle corresponding to the edge of the pad portion (21) is D1, the pad portion (21) has a first end (2141) and a second end (2142), the first end (2141) has two pad end points (2143), the included angle between lines connecting each of the two pad end points (2143) and the center of the pad portion (21) is 2θ2, the diameter of the through hole (142) of the positive electrode current collector (14) is D3, the diameter of the annular bottom wall (141) of the positive electrode current collector (14) is D4, the thickness of the positive electrode current collector (14) is t3, and the length L1 of the pad portion satisfies L1 = D1 * cos θ2 and 1.02 * D3 * cos θ2 ≦ L1 ≦ 0.98 * (D4 - 2t3) * cos θ2.

31. The button cell (1) according to claim 30.

32. The elastic sheet portion (22) has a first elastic sheet end portion (2221) and a second elastic sheet end portion (2222), the first elastic sheet end portion has two elastic sheet end points (2223), the included angle between lines connecting each of the two elastic sheet end points (2223) and the center of the elastic sheet portion (22) is 2θ3, and the length L2 of the elastic sheet portion (22) satisfies 1.5*w3≦L2≦0.98*D3*cosθ3.

32. The button cell battery (1) according to claim 31.

33. A method for manufacturing a pad (20) for a button battery according to any one of claims 16 to 23 or 26 to 32, comprising: Manufacturing an elastic sheet set (300) formed into a strip shape by a press molding process and including a plurality of connected elastic sheets; Manufacturing a pad set (400) formed in a band shape by a press molding process and including a plurality of connected pads; and adjusting the elastic sheet set (300) and the pad set (400) so that their centers are overlapped, and then welding the elastic sheet set (300) and the pad set (400) together using laser welding equipment to form a plurality of connected pads (20). A method for manufacturing a pad (20).

34. A method for assembling the button battery according to any one of claims 1 to 7, any one of claims 15 to 23, or any one of claims 26 to 32, comprising: After adjusting the relative position of the pad (20) and the positive electrode cap (11), the pad (20) and the positive electrode cap (11) are welded together to form a positive electrode cap assembly (220); placing a positive electrode sheet (15) in a positive electrode current collector (14) to form a positive electrode assembly (100); placing a negative electrode sheet (16) in a negative electrode cap (12) to form a negative electrode assembly (500); sequentially placing a separator (17) and the positive electrode assembly (100) in the negative electrode assembly (500) to form an assembly; injecting an electrolyte (19) into the assembly; and covering the end of the assembly with the positive electrode cap assembly (220). How to assemble a button cell battery.

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