Button cell

Abstract

The utility model provides a button cell, which comprises a positive electrode cover assembly, a negative electrode cover assembly, a positive electrode connecting assembly, a negative electrode connecting assembly, a positive electrode connecting assembly and a negative electrode connecting assembly, the positive electrode current collector is arranged in the positive electrode cover and is provided with an accommodating cavity, and a through hole is formed in the bottom wall of the positive electrode current collector; the positive plate is positioned in the accommodating cavity; wherein the elastic sheet comprises a first extension part and a second extension part which are arranged in a crossed manner, the length of the first extension part is L1, the length of the second extension part is L2, L1 is greater than L2, the second extension part and / or the first extension part are / is provided with a convex structure, and the convex structure penetrates through the through hole and is fixed on the positive plate.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a button cell. Background Art

[0002] As an energy source, stable power supply is a basic requirement for button cells. Since a high internal resistance of a button cell can lead to a shortened battery life, reduced capacity, accelerated self-discharge rate, decreased voltage, and battery heating, the internal resistance of the battery is usually used as one of the important indicators to evaluate the reliability and stability of button cells, that is, it is required that the initial internal resistance of the button cell is lower than 10 Ω, and the internal resistance of the battery is lower than 20 Ω after being stored at 85 °C for one week.

[0003] With the development of society and the change of the market, the application environment of button cells is becoming more and more harsh. For example, it is required that the button cell can supply power stably under high temperature, high humidity, high pressure, high-frequency vibration, and high-speed centrifugation, that is, when stored at 125 °C for 100 h, the internal resistance of the battery is lower than 15 Ω. However, as the storage temperature of the button cell increases from 85 °C to 125 °C, in the related art, the structure of the positive current collector and the assembly process between the positive current collector and the positive electrode cap cause an increase in the bulging degree of the positive electrode cap, an increase in the gap between the positive current collector and the positive electrode cap, and further lead to poor contact between the positive current collector and the positive electrode cap and a decrease in the current collection effect of the positive current collector, thereby causing the battery to be unable to supply power stably and further unable to meet the requirements of the current application scenarios of button cells. Summary of the Utility Model

[0004] An embodiment of the utility model provides a button cell, which can solve the technical problem of unstable internal structure of the button cell.

[0005] An embodiment of the utility model provides a button cell, including:

[0006] A positive electrode cap assembly, including a positive electrode cap and a spring piece, the spring piece is installed inside the positive electrode cap;

[0007] A positive current collector, arranged inside the positive electrode cap and provided with a receiving cavity, and a through hole is arranged on the bottom wall of the positive current collector;

[0008] A positive electrode sheet, located inside the receiving cavity;

[0009] Wherein, the spring piece includes a first extension part and a second extension part which are arranged crosswise, the length of the first extension part is L1, the length of the second extension part is L2, L1 > L2, and the second extension part and / or the first extension part are / is provided with a convex structure, and the convex structure passes through the through hole and is fixed to the positive electrode sheet.

[0010] Advantageous Effects of the Embodiment of the Utility Model:

[0011] In an embodiment of the present utility model, by adding a spring piece in a button cell, the spring piece is connected to the positive electrode cover. The length of the first extension part of the spring piece is greater than that of the second extension part, and both ends of the first extension part are connected to the positive electrode current collector. The second extension part is located within the area where the through hole of the positive electrode current collector is located. The second extension part and / or the first extension part are also provided with a convex structure, which is used to further fix the positive electrode plate, so that when the positive electrode cover bulges, the positive electrode cover remains in contact with the positive electrode plate inside the positive electrode current collector, thereby improving the stability of the internal structure of the battery. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present utility model. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0013] Figure 1 It is a sectional view of a button cell provided by an embodiment of the present utility model from an angle;

[0014] Figure 2 It is another sectional view of a button cell provided by an embodiment of the present utility model from an angle;

[0015] Figure 3 It is a sectional view of a button cell provided by another embodiment of the present utility model from an angle;

[0016] Figure 4 It is a three-dimensional view of the spring piece provided by an embodiment of the present utility model;

[0017] Figure 5a It is a strip diagram of the spring piece assembly provided by an embodiment of the present utility model;

[0018] Figure 5b It is a strip diagram of the spring piece assembly provided by another embodiment of the present utility model;

[0019] Figure 6 It is a sectional view of the spring piece provided by an embodiment of the present utility model from an angle;

[0020] Figure 7a It is provided by an embodiment of the present utility model Figure 6 Partial enlarged view of;

[0021] Figure 7b It is provided by another embodiment of the present utility model Figure 6 Partial enlarged view of;

[0022] Figure 8 It is a sectional view of the elastic piece provided by the embodiment of the present utility model from another angle;

[0023] Figure 9a It is a three-dimensional view of the elastic piece provided by the second embodiment of the present utility model;

[0024] Figure 9b It is a three-dimensional view of the elastic piece provided by the third embodiment of the present utility model;

[0025] Figure 9c It is a three-dimensional view of the elastic piece provided by the fourth embodiment of the present utility model;

[0026] Figure 9d It is a three-dimensional view of the elastic piece provided by the fifth embodiment of the present utility model;

[0027] Figure 10 It is a three-dimensional view of the elastic piece and the positive electrode cover after welding provided by the embodiment of the present utility model;

[0028] Figure 11 It is a sectional view of the elastic piece and the positive electrode cover after welding provided by the embodiment of the present utility model;

[0029] Figure 12 It is a front view of the elastic piece and the positive electrode cover after welding provided by the embodiment of the present utility model;

[0030] Figure 13 It is a position diagram of the welding points of the elastic piece and the positive electrode cover after welding provided by the embodiment of the present utility model;

[0031] Figure 14 It is a position schematic diagram of the elastic piece and the positive electrode current collector from an angle provided by the embodiment of the present utility model;

[0032] Figure 15a It is a schematic diagram of the construction lines of the elastic piece provided by an embodiment of the present utility model;

[0033] Figure 15b It is a schematic diagram of the construction lines of the elastic piece provided by another embodiment of the present utility model;

[0034] Figure 16 It is a position schematic diagram of the elastic piece and the positive electrode current collector from another angle provided by the embodiment of the present utility model;

[0035] Figure 17 It is a sectional view of the elastic piece and the positive electrode current collector provided by the embodiment of the present utility model;

[0036] Figure 18a It is a position schematic diagram of the elastic piece and the positive electrode current collector provided by a comparative example of the present utility model;

[0037] Figure 18bIt is a schematic diagram of the position of the elastic sheet and the positive current collector provided by another comparative example of the present utility model;

[0038] Figure 19 It is a schematic diagram of the size of the elastic sheet provided by the embodiment of the present utility model;

[0039] Figure 20a It is a sectional view of the elastic sheet provided by Embodiment 1 of the present utility model;

[0040] Figure 20b It is a sectional view of the elastic sheet provided by Comparative Example 1 of the present utility model;

[0041] Figure 20c It is a sectional view of the elastic sheet provided by Comparative Example 2 of the present utility model;

[0042] Reference numerals in the drawings:

[0043] 1. Button cell; 11. Positive cap; 12. Negative cap; 13. Sealing ring; 14. Positive current collector; 141. Annular bottom wall; 142. Through hole; 143. Side wall; 144. Receiving cavity; 15. Positive electrode sheet; 16. Negative electrode sheet; 17. Separator; 19. Electrolyte; 20. Elastic sheet; 21. First extension part; 211. First extension side; 212. First extension end; 22. Second extension part; 221. Second extension end; 23. Protrusion structure; 231. First flange; 232. Second flange; 233. Protrusion; 23a. Exceeding area; 23b. Non-exceeding area; 24. Base surface; 25. Positioning hole; 200. Elastic sheet assembly; 210. Welding point; 220. Positive cap assembly; Q1. First area; Q2a. First part of the second area; Q2b. Second part of the second area; Q3a. First part of the third area; Q3b. Second part of the third area; Detailed implementation manners

[0044] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present utility model. In addition, it should be understood that the specific implementation manners described herein are only used to illustrate and explain the present utility model, and are not used to limit the present utility model. In the present utility model, unless otherwise stated, the orientation terms such as "upper" and "lower" usually refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the drawings; and "inner" and "outer" are for the contour of the device.

[0045] The button cell mainly consists of 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 related technologies, considering the cost of battery assembly process, usually after placing the positive electrode sheet inside the positive electrode current collector, then placing the positive electrode current collector inside the positive electrode cap, and then making the positive electrode cap and the positive electrode current collector in close contact through sealing and pressing.

[0046] Since the positive electrode current collector is directly placed inside the positive electrode cap and there is no limiting structure between the positive electrode current collector and the positive electrode cap, the positive electrode current collector is prone to move inside the button cell. Especially under severe vibration and high-speed centrifugation, the positive electrode current collector is severely displaced, resulting in poor contact between internal parts, and making the button cell prone to problems such as current fluctuation, low voltage, low capacity, and high resistance. Further, when the button cell is stored at high temperature, the positive electrode cap bulges, and a gap is formed between the positive electrode current collector and the positive electrode cap, further leading to poor contact between internal parts, and making the button cell have problems such as low voltage, poor discharge, and high internal resistance.

[0047] As an energy source, stable power supply is a basic requirement for the button cell. Since a high internal resistance of the button cell will lead to a shortened battery life, reduced capacity, accelerated self-discharge rate, decreased voltage, and battery heating, usually the battery internal resistance is used as one of the important indicators to evaluate the reliability and stability of the button cell, that is, it is required that the initial internal resistance of the button cell is lower than 10 Ω, and the battery internal resistance is lower than 20 Ω after being stored at 85 °C for one week.

[0048] With the development of society and the change of the market, the application environment of the button cell is becoming more and more harsh. For example, it is required that the button cell can supply power stably under high temperature, high humidity, high pressure, high-frequency vibration, and high-speed centrifugation, that is, when stored at 125 °C for 100 h, the battery internal resistance is lower than 15 Ω.

[0049] However, as the storage temperature of the button cell is increased from 85 °C to 125 °C, the existing structure of the positive electrode current collector and the assembly process between it and the positive electrode cap make the degree of bulging of the positive electrode cap increase, the gap between the positive electrode current collector and the positive electrode cap increase, and further lead to poor contact between the positive electrode current collector and the positive electrode cap and a decrease in the current collection effect of the positive electrode current collector, and then cause a sharp increase in the battery internal resistance, unable to meet the requirements of the current application scenarios of the button cell.

[0050] To improve the stability of the electrical performance of the button cell in extreme environments, the present utility model optimizes the internal structure of the button cell to enhance the current collection effect.

[0051] Reference Figures 1 to 3 As shown, the present utility model provides a button cell 1, which includes a positive electrode cap 11, a negative electrode cap 12, a sealing 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.

[0052] The positive electrode cap 11 is provided as an open cap-shaped structure. As Figure 3 shown, the outer side surface of the positive electrode cap 11 can be configured as a vertical surface structure. As Figure 1 shown, the outer side surface of the positive electrode cap 11 can also be provided with a boss structure.

[0053] The negative electrode cap 12 is provided as an open cap-shaped structure. The inner diameter and outer diameter of the positive electrode cap 11 are both larger than the inner diameter and outer diameter of the negative electrode cap 12, so that the positive electrode cap 11 can be covered on the outside of the negative electrode cap 12.

[0054] The sealing ring 13 is arranged at the connection between the positive electrode cap 11 and the negative electrode cap 12. The sealing ring 13 forms a wrapping structure for at least a part of the wall of the negative electrode cap 12, so that a sealed connection structure is formed between the positive electrode cap 11 and the negative electrode cap 12. At the same time, the sealing ring 13 is also used to provide insulation between the positive electrode cap 11 and the negative electrode cap 12.

[0055] The positive electrode current collector 14 is received in the inner cavity of the positive electrode cap 11. The positive electrode current collector 14 can be set as any one of a current collecting ring, a current collecting net and a current collecting sheet. As Figure 1 described, the positive electrode current collector 14 is set as a current collecting ring. The positive electrode current collector 14 includes an annular bottom wall 141 and a side wall 143 circumferentially connected to the annular bottom wall 141. The annular bottom wall 141 and the side wall 143 enclose a receiving cavity 144. A through hole 142 is provided on 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 cap 12.

[0056] The positive electrode plate 15 is received inside the receiving cavity 144 of the positive electrode current collector 14 and is in contact with the positive electrode cap 11 through the through hole 142.

[0057] The negative electrode plate 16 is received in the inner cavity of the negative electrode cap 12.

[0058] The separator 17 is arranged between the positive electrode plate 15 and the negative electrode plate 16 and is used to separate the positive electrode plate 15 and the negative electrode plate 16. The projection surface of the negative electrode plate 16 on the separator 17 can be substantially coincident with the projection surface of the positive electrode plate 15 on the separator 17.

[0059] The electrolyte 19 is filled inside the entire button cell 1. After the electrolyte is injected, the internal structures such as the negative electrode plate and the positive electrode plate are in a state of being immersed in the electrolyte, and the charged ions in the positive electrode plate and the negative electrode plate are connected by the electrolyte to conduct current.

[0060] For further reference Figures 1 to 3As shown, the button cell 1 further includes a spring piece 20, wherein the spring piece 20 is connected to the inner surface of the positive electrode cap 11. The spring piece 20 includes a first extension portion 21 and a second extension portion 22 which are cross - arranged. The length L1 of the first extension portion 21 is greater than the length L2 of the second extension portion 22. Both ends of the first extension portion 21 are connected to the positive electrode current collector 14. The second extension portion 22 is located inside the positive electrode current collector 14. The second extension portion 22 and / or the first extension portion 21 are provided with a convex structure 23, and the convex structure 23 is used to fix the positive electrode sheet 15.

[0061] By adding the spring piece 20 in the button cell 1, the spring piece 20 is connected to the positive electrode cap 11. The length of the first extension portion 21 of the spring piece 20 is greater than the length of the second extension portion 22. Both ends of the first extension portion 21 are connected to the positive electrode current collector 14. The second extension portion 22 is located inside the positive electrode current collector 14. The second extension portion 22 and / or the first extension portion 21 are further provided with a convex structure 23, and the convex structure 23 is used to further fix the positive electrode sheet 15. The spring piece 20 is arranged to be connected to the positive electrode cap 11 and the positive electrode current collector 14 respectively, and the convex structure 23 on the spring piece 20 is used to further fix the positive electrode sheet 15, so that when the positive electrode cap 11 bulges, the positive electrode cap 11 remains in contact with the positive electrode sheet 15 inside the positive electrode current collector 14, thereby improving the stability of the internal structure of the battery.

[0062] Further referring to Figure 4 and Figure 6 As shown, the first extension portion 21, the second extension portion 22 and the convex structure 23 of the spring piece 20 are integrally formed. The thickness of the spring piece 20 is set to t, and 0.05mm ≤ t ≤ 0.30mm.

[0063] The material for preparing the spring piece 20 can be one of SUS44, SUS304, SUS430, SUS316. In a preferred embodiment, the spring piece 20 is prepared from SUS430, so that the spring piece 20 itself has magnetism, which is beneficial to reducing the welding between the spring piece 20 and the positive electrode cap 11 or the positive electrode current collector 14, reducing the welding difficulty and improving the feasibility of welding.

[0064] The thickness of the elastic member is set to be from 0.05 mm to 0.30 mm. In a further preferred embodiment, the thickness of the elastic sheet 20 is set to be from 0.10 mm to 0.20 mm. In a specific embodiment, the thickness of the elastic sheet 20 can be 0.05 mm, 0.10 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, and the values between any two of the above or the ranges between any two of the above values. The inventor found through research that when the thickness t of the elastic sheet 20 < 0.05 mm, the strength of the elastic sheet 20 is low and it is easy to deform, and the elastic connection function of the elastic sheet 20 cannot be exerted; when the thickness of the elastic sheet 20 > 0.30, the volume of the elastic sheet 20 increases, occupying the internal space of the battery, resulting in a decrease in battery capacity.

[0065] As Figure 5a and Figure 5b shown, the present application also provides a method for manufacturing an elastic sheet. The elastic sheet is processed and formed by a stamping process. During the stamping process, a plurality of elastic sheets are formed into a roll-shaped plurality of elastic sheet assemblies 200 in the form of a connecting edge. Further referring to Figure 5a shown, a plurality of elastic sheets 20 are connected by a convex structure 23. A single elastic sheet 20 formed by cutting two adjacent elastic sheets 20 still includes a protruding end structure at its side. Further referring to Figure 5b shown, a plurality of elastic sheets 20 are directly connected, and the sides of a single elastic sheet 20 formed by cutting two adjacent elastic sheets 20 are arranged flush.

[0066] Further referring to Figure 4 shown, the convex structure 23 for fixing the positive electrode sheet 15 provided on the elastic sheet 20 includes a first flange 231 and a second flange 232, wherein the first flange 231 and the second flange 232 are respectively located at both ends of the second extension portion 22.

[0067] By respectively arranging the first flange 231 and the second flange 232 at both ends of the second extension portion 22, the first flange 231 and the second flange 232 can be embedded into the positive electrode sheet 15. Compared with arranging the convex structure 23 at other positions of the second extension portion 22, arranging the convex structure 23 at both ends of the second extension portion 22 can increase the contact area between the elastic sheet 20 and the positive electrode sheet 15, thereby enhancing the limiting effect of the convex structure 23 on the positive electrode sheet 15. Especially when the button cell 1 is in extreme vibration and centrifugation, the above first flange 231 and second flange 232 can effectively reduce the position movement of the positive electrode current collector 14 and the elastic sheet 20 inside the battery, reduce the mutual impact force between the positive electrode sheet 15, the negative electrode sheet 16 and the electrolyte 19 of the battery, further reduce the internal resistance of the battery, and improve the stability of the battery performance.

[0068] As Figure 6As shown, the height of the first flange 231 or the second flange 232 is set to h1, where 2*t ≤ h1 ≤ 10*t; and / or, the included angle formed by the extension line of the outer tangent plane of the first flange 231 or the second flange 232 and the plane where the second extension portion 22 is located is 90° to 150°.

[0069] In a preferred embodiment, the first flange 231 and the second flange 232 are symmetrically arranged about the center of the elastic piece 20. The height by which the first flange 231 protrudes from the base surface 24 of the second extension portion 22 is the same as the height by which the second flange 232 protrudes from the base surface 24 of the second extension portion 22, and both are set to h1. In some examples, h1 can be 2t, 3t, 4t, 5t, 6t, 7t, 8t, 9t, 10t, a value between any two of the above values, or a range between any two of the above values. The inventor found through research that when the height h1 of the first flange 231 or the second flange 232 satisfies 2*t ≤ h1 ≤ 10*t, after the first flange 231 and the second flange 232 are embedded in the positive electrode sheet 15, the overall structure of the positive electrode sheet 15 will not be damaged by the first flange 231 or the second flange 232 to cause phenomena such as broken sheets or powder falling off, and the first flange 231 and the second flange 232 will not be deformed during the process of being embedded in the positive electrode sheet 15. Specifically, when the height h1 of the first flange 231 or the second flange 232 < 2t, since the depth of the first flange 231 or the second flange 232 embedded in the positive electrode sheet 15 is insufficient, when the positive electrode cover 11 bulges outwards, the first flange 231 or the second flange 232 is likely to be separated from the positive electrode sheet 15, resulting in poor contact between the entire elastic piece 20 and the positive electrode current collector 14; when the height h1 of the first flange 231 or the second flange 232 > 10t, the first flange 231 and the second flange 232 need to be embedded in the positive electrode sheet 15 to a relatively deep depth, such that during the process of the first flange 231 or the second flange 232 being embedded in the positive electrode sheet 15, the elastic piece 20 is likely to be deformed and the overall structure of the positive electrode sheet 15 is also likely to be damaged.

[0070] Continue to refer to Figure 6 As shown, the included angle formed by the extension line of the outer tangent plane of the first flange 231 or the second flange 232 and the plane where the second extension portion 22 is located is θ1, and θ1 needs to satisfy: 90° ≤ θ1 ≤ 150°.

[0071] In a specific implementation, the first flange 231 or the second flange 232 is symmetrically arranged about the center of the elastic sheet 20. The angle formed by the extension line of the outer tangent plane of the first flange 231 and the plane where the second extension part 22 is located is the same as the angle formed by the extension line of the outer tangent plane of the second flange 232 and the plane where the second extension part 22 is located, and both are set as θ1. θ1 needs to satisfy: 90° ≤ θ1 ≤ 150°. For example, θ1 can be 90°, 100°, 110°, 120°, 130°, 140°, 150°, and the angles between any two of the above angles or the ranges between any two of the above angles. The inventor found through research that when θ1 < 90°, it is difficult for the first flange 231 or the second flange 232 to be embedded into the positive electrode sheet 15. When θ1 > 150°, the range corresponding to the embedding of the first flange 231 or the second flange 232 into the positive electrode sheet 15 is too large, which is likely to damage the overall structure of the positive electrode sheet 15 and cause it to shed powder and fall off.

[0072] The above-mentioned first flange 231 or second flange 232 can be set as a straight-edge inclined structure, such as Figure 7a shown. The first flange 231 or the second flange 232 can also be set as a corrugated inclined structure, such as Figure 7b shown. The first flange 231 or the second flange 232 can also be set as an inclined structure with a sharp corner at the end.

[0073] Further referring to Figure 4 and Figure 8 shown, the convex structure 23 includes at least two convexes 233 arranged on the first extension part 21, and at least two of the convexes 233 are symmetrically arranged on both sides of the second extension part 22.

[0074] By arranging at least two convexes 233 on the first extension part 21, the two convexes 233 can be further embedded into the positive electrode sheet 15, thereby increasing the contact area between the elastic sheet 20 and the positive electrode sheet 15, and thus increasing the limiting effect of the convex structure 23 on the positive electrode sheet 15. When the button battery 1 is in an extreme vibration or centrifugal situation, etc., the above-mentioned convex structure 23 can effectively prevent the positive electrode current collector 14 and the elastic sheet 20 from having relative displacement inside the button battery 1, thereby reducing the mutual impact force between the positive electrode sheet 15, the negative electrode sheet 16, and the electrolyte 19, reducing the internal resistance of the button battery 1, and further improving the stability of the electrical performance of the button battery 1.

[0075] Further, two protrusions 233 are provided on the first extension portion 21. The two protrusions 233 are symmetrically arranged with respect to the second extension portion 22. A first flange 231 and a second flange 232 are respectively provided at both ends of the second extension portion 22. The first flange 231 and the second flange 232 are symmetrically arranged with respect to the first extension portion 21. Since the first extension portion 21 and the second extension portion 22 are cross - arranged, the two protrusions 233 are configured to provide a fixing force in a first direction to the positive electrode plate 15, and the first flange 231 and the second flange 232 are configured to provide a fixing force in a second direction to the positive electrode plate 15. The positive electrode plate 15 is simultaneously subjected to the fixing force in the first direction and the fixing force in the second direction provided by the elastic piece 20, so that the elastic piece 20 can fully restrict the displacement of the positive electrode plate 15 relative to the elastic piece 20 in an extreme environment.

[0076] As Figure 8 shown, the height of the protrusion 233 is set to h2, and 1.5*t ≤ h2 ≤ 3*t.

[0077] In a specific implementation, the height h2 of the protrusion 233 protruding from the plane where the first extension portion 21 is located can be set to 1.5t, 2.0t, 2.5t, 3.0t, and values between any two of the above or ranges between any two of the above values. The inventor found through research that when the height h2 of the protrusion 233 < 1.5t, since the two protrusions 233 are not embedded deep enough into the positive electrode plate 15, when the positive electrode cover 11 bulges outwards, the two protrusions 233 are likely to disengage from the positive electrode plate 15, resulting in poor contact between the entire elastic piece 20 and the positive electrode current collector 14; when the height h2 of the two protrusions 233 > 3*t, then the two protrusions 233 need to be embedded deeper into the positive electrode plate 15, making the process of embedding the two protrusions 233 into the positive electrode plate 15 more difficult, and the overall structure of the positive electrode plate 15 is also likely to be damaged, resulting in powder - dropping problems.

[0078] The overall shape of the two protrusions 233 can be set as a triangular pyramid shape or a polygonal prism shape with a sharp - corner structure.

[0079] Further referring to Figure 4 、 Figures 9a to 9d shown, the orthographic projection of the elastic piece 20 on the positive electrode cover 11 is set as a cross shape, a rice - shape, or a combined shape of a circle and a cross.

[0080] The base surface 24 of the elastic piece 20 can be set as a cross - shaped structure. The first extension portion 21 and the second extension portion 22 form a cross - portion through cross - arrangement. The first extension portion 21 includes a first part of the first extension portion 21 and a second part of the first extension portion 21 that are symmetrically arranged with respect to the cross - portion. The second extension portion 22 includes a first part of the second extension portion 22 and a second part of the second extension portion 22 that are symmetrically arranged with respect to the cross - portion.

[0081] In some examples, such as Figure 4 shown, the base surface 24 of the elastic piece 20 is set as a regular cross-shaped structure, wherein the two parts of the first extension part 21 and the two parts of the second extension part 22 are both set as regular rectangular structures. In other alternative examples, the base surface 24 of the elastic piece 20 can be set as an irregular cross-shaped structure, such as Figure 9a shown, the base surface 24 of the elastic piece 20 is set as an irregular cross-shaped structure, wherein the two sides of the two parts of the first extension part 21 are set as arc-edge structures, or such as Figure 9b shown, the base surface 24 of the elastic piece 20 is set as an irregular cross-shaped structure, wherein the two parts of the first extension part 21 are both set as fan-shaped structures, and the two parts of the second extension part 22 are also set as fan-shaped structures, or such as Figure 9c shown, the base surface 24 of the elastic piece 20 includes an outer ring part and an inscribed part. The outer ring part is constructed as a closed circular ring structure, and the inscribed part is set as a cross-shaped structure. The two ends of the first extension part 21 are connected to the circular ring edge. Further referring to Figure 9d shown, the base surface 24 of the elastic piece 20 is set as a cross-star structure or other polygon structures. A plurality of extension parts are arranged on the outer side of the intersection part, that is, a third extension part, a fourth extension part or a fifth extension part is also arranged between the first extension part 21 and the second extension part 22, wherein the length of the first extension part 21 is greater than the lengths of the second extension part 22, the third extension part and the fourth extension part.

[0082] Further referring to Figures 10 to 12 shown, the elastic piece 20 is provided with a positioning hole 25, and the positioning hole 25 is used for positioning when the elastic piece 20 is welded to the positive electrode cover 11. The elastic piece 20 is welded to the inner surface of the positive electrode cover 11, and the concentricity between the elastic piece 20 and the positive electrode cover 11 is less than or equal to 0.3 mm.

[0083] The elastic piece 20 is connected to the inner surface of the positive electrode cover 11 by welding. A positioning hole 25 is arranged at the center position of the elastic piece 20. The intersection area of the first extension part 21 and the second extension part 22 is located at the center position of the elastic piece 20, and the positioning hole 25 is located at the center of the intersection area of the first extension part 21 and the second extension part 22.

[0084] Put Figure 5a and Figure 5bThe coiled shrapnel 20 assembly shown is transferred into a laser welding device and cut into individual shrapnel 20. At the same time, the positive electrode cap 11 is placed in the jig by means of a vibrating disk feeder. During the welding process of the shrapnel 20 and the positive electrode cap 11, the shrapnel 20 is placed on the inner surface of the positive electrode cap 11 through the positioning hole 25 of the shrapnel 20 clamped by the jig and centered through the above-mentioned positioning hole 25, and the shrapnel 20 and the positive electrode cap 11 are welded together by laser welding.

[0085] During the assembly process, it is necessary to control the concentricity between the shrapnel 20 and the positive electrode cap 11 ≤ 0.3 mm. In a preferred embodiment, the concentricity between the shrapnel 20 and the positive electrode cap 11 ≤ 0.1 mm. The inventor found through research that if the concentricity between the positive electrode cap 11 and the shrapnel 20 > 0.3 mm, it will cause serious deviation between the shrapnel 20 and the positive electrode cap 11, and then cause serious deviation between the shrapnel 20 and the positive electrode current collector 14, and further cause the current collection effect of the positive electrode current collector 14 to decline, further affecting the electrical performance of the button cell 1.

[0086] As Figure 13 shown, the solder joints 210 formed by welding the shrapnel 20 and the positive electrode cap 11 are at least two, and at least two of the solder joints 210 are symmetrically arranged about the center of the shrapnel 20.

[0087] The inventor found through research that during the welding process of the shrapnel 20 and the positive electrode cap 11, the number of solder joints 210 formed by welding the shrapnel 20 and the positive electrode cap 11 is preferably two, and the two solder joints 210 help to improve the welding strength between the shrapnel 20 and the positive electrode cap 11. If the number of solder joints 210 formed by welding the shrapnel 20 and the positive electrode cap 11 is one, it will cause the shrapnel 20 to be prone to deviation and warping relative to the positive electrode cap 11. If the number of solder joints 210 formed by welding the shrapnel 20 and the positive electrode cap 11 is more than two, it will cause the welding process between the shrapnel 20 and the positive electrode cap 11 to be complicated and increase the welding cost at the same time.

[0088] Continue to refer to Figure 13 shown, by optimizing the position of the welding area between the shrapnel 20 and the positive electrode cap 11, the stability performance of the button cell 1 can be further improved.

[0089] The weldable base surface 24 of the elastic sheet 20 is divided into five regions, namely the first region Q1, the first part Q2a of the second region, the second part Q2b of the second region, the first part Q3a of the third region, and the second part Q3b of the third region. The first region Q1 is located in the intersection region of the first extension 21 and the second extension 22. The first part Q2a and the second part Q2b of the second region are arranged on both sides of the first region Q1 and located on the first extension 21. The first part Q3a and the second part Q3b of the third region are arranged on both sides of the first region Q1 and located on the second extension 22. The length of the first extension 21 is L3, and the length L3 of the first region Q1 extending along the first extension 21 satisfies: L3 = 0.5L1. The width of the first region Q1 extending along the second extension 22 is equal to the width of the first extension 21.

[0090] The position of the solder joint 210 between the elastic sheet 20 and the positive electrode cover 11 can be set above the first region Q1 or the first part Q2a and the second part Q2b of the second region. In a further preferred embodiment, the position of the solder joint 210 between the elastic sheet 20 and the positive electrode cover 11 is preferably set above the first part Q2a and the second part Q2b of the second region, and the position of the solder joint 210 between the elastic sheet 20 and the positive electrode cover 11 is located outside the first part Q3a and the second part Q3b of the third region. The inventor found through research that if the position of the solder joint 210 between the elastic sheet 20 and the positive electrode cover 11 is located above the first part Q3a and the second part Q3b of the third region, it will cause the first part Q3a and the second part Q3b of the third region where the elastic sheet 20 is located to lose elasticity. When the positive electrode cover 11 bulges, since the regions where the first flange 231 and the second flange 232 on the elastic sheet 20 are welded to the positive electrode cover 11, it will further cause the first flange 231 and the second flange 232 to be separated from the positive electrode sheet 15, and further cause poor contact between the elastic sheet 20 and the positive electrode sheet 15, making the limiting effect of the first flange 231 and the second flange 232 on the positive electrode sheet 15 fail.

[0091] The present invention also provides an assembly method for a button battery, and the assembly method includes:

[0092] Forming a positive electrode cover assembly 220 by welding the positive electrode cover 11 and the elastic sheet 20;

[0093] Pressing the positive electrode sheet 15 into the inner cavity of the positive electrode current collector 14 to form a sleeve positive electrode;

[0094] Placing the negative electrode in the inner cavity of the negative electrode cover 12, and sequentially placing the separator 17 and the sleeve positive electrode. Wrapping a sealing ring 13 on the outer surface of the negative electrode cover 12, injecting the electrolyte 19, and then covering the above positive electrode cover assembly 220 to seal and form a button battery 1. After the assembly is completed, the button battery 1 is pre-discharged and aged.

[0095] The shrapnel 20 is welded to the inner surface of the positive electrode cap 11, and the positive electrode current collector 14 is placed on the shrapnel 20. The positions between the positive electrode current collector 14 and the shrapnel 20 are not completely concentric, that is, there is a positional deviation between the center of the positive electrode current collector 14 and the center of the shrapnel 20.

[0096] As Figures 14 to 17 described, the positive electrode current collector 14 includes an annular bottom wall 141, and through holes 142 are provided on the annular bottom wall 141. Both ends of the first extension portion 21 are connected to the annular bottom wall 141.

[0097] As Figure 15a 、 Figure 15b 、 Figure 16 and Figure 17 shown, the diameter of the circumscribed circle corresponding to the edge of the first extension portion 21 is set as D1, the diameter of the circumscribed circle corresponding to the edge of the second extension portion 22 is set as D2, the diameter of the through hole 142 of the positive electrode current collector 14 is set as D3, the diameter of the annular bottom wall 141 of the positive electrode current collector 14 is set as D4, the thickness of the positive electrode current collector 14 is set as t1. The first extension portion 21 includes two ends, and one of the sides where one end is located includes two endpoints. The included angle between the connecting lines of the two endpoints and the center of the shrapnel 20 is 2θ2.

[0098] Further referring to Figure 15a shown, in one embodiment, the first extension portion 21 includes two first extension sides 211, and a protruding first extension end 212 is provided on each first extension side 211. The side where the first extension end 212 is located includes two first extension endpoints, and the included angle between the connecting lines of the two first extension endpoints and the center of the shrapnel 20 is set as 2θ2.

[0099] Further referring to Figure 15b shown, in another embodiment, the first extension portion 21 includes two first extension sides 211. The first extension sides 211 are set as straight sides, and the first extension end 212 is formed by the first extension sides 211. The first extension end 212 includes two first extension endpoints, and the included angle between the connecting lines of the two first extension endpoints and the center of the shrapnel 20 is set as 2θ2.

[0100] To ensure that both ends of the first extension portion 21 of the elastic piece 20 are always in contact with the annular bottom wall 141 of the positive current collector 14, that is, both ends of the first extension portion 21 are always located in the area Q3 where the annular bottom wall 141 of the positive current collector 14 is located, and both ends of the first extension portion 21 still overlap on the area Q3 where the annular bottom wall 141 of the positive current collector 14 is located after the battery is sealed, the inventor found through research that the length L1 of the first extension portion 21 satisfies: L1 = D1 * cosθ2. In a further preferred embodiment, 1.02 * D3 ≤ L1 / cosθ2 ≤ 0.98 * (D4 - 2t1), that is, 1.02 * D3 * cosθ2 ≤ L1 ≤ 0.98 * (D4 - 2t1) * cosθ2.

[0101] Further referring to Figure 18a As shown, if the length of the first extension portion 21 is set to L1a, L1a > 0.98 * (D4 - 2t1) * cosθ2, then at least a part of the area where one flange of the elastic piece 20 is located exceeds the edge of the positive current collector 14, such as Figure 18a the exceeding area 23a shown, and the area where the other flange of the elastic piece 20 is located does not exceed the edge of the positive current collector 14, such as Figure 18a the non - exceeding area 23b shown. During the sealing process of the button cell 1, since the edge strength of the positive current collector 14 is greater than the strength of the plane where the bottom wall of the positive current collector 14 is located, the height corresponding to the exceeding area 23a where the elastic piece 20 exceeds the edge of the positive current collector 14 is greater than the height corresponding to the non - exceeding area 23b where the elastic piece 20 does not exceed the edge of the positive current collector 14. A height difference appears inside the positive current collector 14, resulting in a poor current collection effect of the positive current collector 14.

[0102] Further referring to Figure 18b As shown, if the length of the first extension portion 21 is set to L1b, L1b < 1.02 * D3 * cosθ2, the area where one flange of the elastic piece 20 is located is in the area where the through - hole 142 of the positive current collector 14 is located, such as Figure 18b the exceeding area 23a shown, and the other flange of the elastic piece 20 is in the plane area where the bottom wall of the positive current collector 14 is located, such as Figure 18b the non - exceeding area 23b shown. During the sealing process of the button cell 1, the height corresponding to the exceeding area 23a where one edge of the elastic piece 20 is in the through - hole 142 of the positive current collector 14 is greater than the height corresponding to the non - exceeding area 23b where the other flange of the elastic piece 20 is in the plane of the bottom wall of the positive current collector 14. A height difference appears inside the positive current collector 14, resulting in a poor current collection effect of the positive current collector 14.

[0103] Further referring to Figure 15a 、 Figure 15b 、 Figure 17 andFigure 19 As shown, the length of the first extension portion 21 is set to L1, the length of the second extension portion 22 is set to L2, the width of the first extension portion 21 extending along the extension direction of the second extension portion 22 is set to w1, the second extension portion 22 includes two second extension end portions 221, each second extension end portion 221 includes two second extension end points, and the included angle between the connection lines between the two second extension end points and the center of the elastic piece 20 is set to 2*θ3, and the diameter of the through hole 142 of the positive current collector 14 is set to D3.

[0104] The first flange 231 and the second flange 232 of the elastic piece 20 are set to have an inclined structure with a certain inclination angle. When the button cell 1 is packaged, the first flange 231 and the second flange 232 are embedded in the positive electrode sheet 15 to limit the positive electrode sheet 15. In order to ensure that when there is a positional deviation between the elastic piece 20 and the positive current collector 14 or the positive electrode cover 11 bulges outward, the first flange 231 and the second flange 232 of the elastic piece 20 can still be embedded in the positive electrode sheet 15 and maintain an elastic connection with the positive electrode sheet 15. The inventor found through research that the length of the second extension portion 22 is preferably set to L2, and L2 satisfies: 1.5*w1 ≤ L2 ≤ 0.98*D3*cosθ3.

[0105] If the length L2 of the second extension portion 22 > 0.98*D3*cosθ3, the relative positional deviation between the elastic piece 20 and the positive current collector 14 is large, resulting in the first flange 231 and / or the second flange 232 not being able to be embedded in the positive electrode sheet 15; if the length L2 of the second extension portion 22 < 1.5*w1, when the positive electrode cover 11 bulges outward, the first flange 231 and / or the second flange 232 of the elastic piece 20 will move outward with the positive electrode cover 11, resulting in the first flange 231 and / or the second flange 232 detaching from the positive electrode sheet 15, the elastic piece 20 losing the elastic limiting effect on the positive current collector 14, and poor contact occurring between the elastic piece 20 and the positive current collector 14.

[0106] In this application, a specific Example 1, Comparative Example 1, and Comparative Example 2 are further provided. By conducting a high-temperature storage experiment on the button cells 1 provided in Example 1, Comparative Example 1, and Comparative Example 2, the changes in the internal resistance of the batteries in Example 1, Comparative Example 1, and Comparative Example 2 in a high-temperature environment are further verified.

[0107] Example 1

[0108] The button cell 1 provided in Example 1 includes an elastic piece 20, and the cross-sectional structure of the elastic piece 20 refers to Figure 20aAs shown, the base surface 24 of the elastic piece 20 adopts a central cross-circular symmetry structure, with length L1 = 0.91*(D4 - 2t1)*cosθ2, L2 = 0.72*D3*cosθ3, t = 0.10, θ1 = 120°, and H1 = 4*t.

[0109] Comparative Example 1

[0110] The button cell provided by Comparative Example 1 includes an elastic piece 20, and the cross-sectional structure of the elastic piece 20 refers to Figure 20b As shown, the base surface 24 of the elastic piece 20 adopts a central cross-circular symmetry structure, with length L1 = 0.91*(D4 - 2t1)*cosθ2, L2 = 0.72*D3*cosθ3, t = 0.10, θ1 = 120°, and H1 = 10*t.

[0111] Comparative Example 2

[0112] The button cell provided by Comparative Example 2 includes an elastic piece 20, and the cross-sectional structure of the elastic piece 20 refers to Figure 20c As shown, the base surface 24 of the elastic piece 20 adopts a central cross-circular symmetry structure, with length L1 = 0.91*(D4 - 2t1)*cosθ2, L2 = 0.72*D3*cosθ3, t = 0.10, θ3 = 120°, and H1 = 2*t.

[0113] (High-temperature storage test: internal resistance evaluation) The button cells of Example 1, Comparative Example 1, and Comparative Example 2 obtained in the above order were subjected to the high-temperature storage test described below, and the change in the internal resistance under high-temperature environment was evaluated therefrom.

[0114] Specifically, first, the internal resistance (Ω) between the positive electrode and the negative electrode of the button cells obtained in Example 1, Comparative Example 1, and Comparative Example 2 was measured respectively by the same method, and is shown as the initial resistance (Ω) in Table 1 below. Then, the button cells of Example 1, Comparative Example 1, and Comparative Example 2 were stored in a high-temperature oven, the internal temperature of the high-temperature oven was set to 125 °C, and the storage time was one week. After storing for one week, the internal resistance (Ω) between the positive electrode and the negative electrode of the button cells of Example 1, Comparative Example 1, and Comparative Example 2 was measured respectively by the same method, and this value was used as the internal resistance after one week of storage (Ω), and is shown in Table 1 below.

[0115] Table 1

[0116]

[0117] Evaluation results:

[0118] As shown in Table 1, Example 1 (flange height is 4t) with an initial internal resistance of 3.461 Ω is compared with Comparative Example 1 (flange height is 10t), and the initial internal resistance of the button cell has an obvious advantage. After disassembling and analyzing the battery, the initial internal resistance of Comparative Example 1 is much higher than that of Example 1. The reason is that after the flange of the shrapnel 20 is embedded in the positive electrode sheet 15, the flange of the shrapnel 20 is deformed and the positive electrode sheet 15 powders, resulting in poor internal contact, and thus the initial internal resistance is much higher than that of Example 1.

[0119] When Example 1 (flange height is 4t) is compared with Comparative Example 2 (flange height is 2t), the difference in the initial internal resistance of the button cell is not significant. However, after the button cell is stored at 125 °C for 1 week, the internal resistance increase rate of the button cell provided by Comparative Example 2 is much higher than that of the button cell provided by Example 1. After taking an imaging analysis of the button cell CT, it is found that the flange part of the shrapnel 20 of the button cell provided by Comparative Example 2 is separated from the positive electrode sheet 15, resulting in poor internal contact of the battery under high-temperature storage.

[0120] The embodiments of the present invention have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A button battery, characterized in that: include: A positive electrode cap assembly, comprising a positive electrode cap and a spring sheet, wherein the spring sheet is installed inside the positive electrode cap; A positive electrode current collector is arranged inside the positive electrode cover and is provided with a receiving cavity, and a through hole is provided on the bottom wall of the positive electrode current collector; A positive electrode sheet, located in the receiving cavity; Wherein, the spring sheet includes a first extension portion and a second extension portion which are cross-arranged, the length of the first extension portion is L1, the length of the second extension portion is L2, L1>L2, the second extension portion and / or the first extension portion are provided with a protruding structure, the protruding structure passes through the through hole and is fixed to the positive electrode sheet.

2. The button battery according to claim 1, characterized in that: The first extension portion, the second extension portion and the protruding structure are integrally formed, and the thickness of the spring sheet is set to t, 0.05≤t≤0.30mm.

3. The button battery according to claim 1, characterized in that: The protruding structure includes a first flange and a second flange, and the first flange and the second flange are respectively arranged at two ends of the second extension portion.

4. The button cell according to claim 3, characterized in that: The height of the first flange or the second flange is set to h1, 2*t<h1<10*t; and / or, An angle formed by an extension line of an outer tangent surface of the first flange or the second flange and a plane where the second extension portion is located is θ1, and θ1 is set to be 90° to 150°.

5. The button battery according to claim 1, characterized in that: The protrusion structure includes at least two protrusions arranged on the first extension portion, and the at least two protrusions are symmetrically arranged and located on both sides of the second extension portion.

6. The button cell according to claim 5, characterized in that: The height of the protrusion is set to h2, 1.5*t≤h2≤3*t.

7. The button cell according to claim 1, characterized in that: The orthographic projection of the spring on the positive electrode cover is arranged in a cross shape, a crisscross shape, or a combination of a circle and a cross shape.

8. The button battery according to any one of claims 1 to 7, characterized in that: The spring sheet is provided with a positioning hole, and the positioning hole is used for positioning the spring sheet when welding with the positive electrode cover. The spring sheet is welded to the positive electrode cover, and the concentricity of the spring sheet and the positive electrode cover is less than or equal to 0.3 mm.

9. The button cell according to claim 8, characterized in that: There are no less than two welding points between the spring sheet and the positive electrode cover, and at least two of the welding points are symmetrically arranged relative to the center point of the spring sheet.

10. The button cell according to claim 9, characterized in that: The spring sheet includes a first area, a second area located on the first extension portion, and a third area located on the second extension portion, the first area is symmetrical about the center line of the first extension portion and the center line of the second extension portion, the second area includes a first part of the second area and a second part of the second area, the first part of the second area and the second part of the second area are respectively located on both sides of the first area, the third area includes a first part of the third area and a second part of the third area, the first part of the third area and the second part of the third area are respectively located on both sides of the first area, the length of the first area is L3, L3=0.5*L1, and the width of the first area is equal to the width of the first extension portion; At least two of the welding spots are located in the first region, and / or at least two of the welding spots are located in the first part of the second region and the second part of the second region; Furthermore, at least two of the welding points are located outside the first portion of the third region and outside the second portion of the third region.

11. The button battery according to any one of claims 1 to 7, characterized in that: The positive electrode current collector includes an annular bottom wall, and both ends of the first extension portion are connected to the annular bottom wall.

12. The button cell according to claim 11, characterized in that: The diameter of the circumscribed circle corresponding to the edge of the first extension portion is set to D1, the first extension portion includes two first extension end portions, one of the first extension end portions includes two first extension endpoints, the angle between the two first extension endpoints and the line connecting the center of the spring is 2*θ2, the diameter of the through hole of the positive current collector is set to D3, the diameter of the annular bottom wall of the positive current collector is set to D4, the thickness of the positive current collector is set to t1, and the length L1 of the first extension portion satisfies: L1=D1*cosθ2, and 1.02*D3*cosθ2≤L1≤0.98*(D4-2*t1)*cosθ2.

13. The button cell according to claim 12, characterized in that: The first extension portion includes two first extension side edges that are arranged opposite to each other, and the first extension end portion is arranged to protrude relative to the first extension side edge; or, the first extension end portion is arranged to be flush with the first extension side edge.

14. The button cell according to claim 12, characterized in that: The width of the first extension portion is set to w1, the diameter of the through hole of the positive electrode collector is set to D3, the second extension portion includes two second extension ends, one of the second extension ends includes two second extension endpoints, the angle between the two second extension endpoints and the line connecting the center of the spring is 2θ3, and the length L2 of the second extension portion satisfies: 1.5*w1≤L2≤0.98*D3*cosθ3.

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