Electrochemical device and electric equipment

Abstract

The application relates to the technical field of batteries, and discloses an electrochemical device and a power utilization equipment. The electrochemical device comprises a shell, an electrode assembly and a first tab. The electrode assembly comprises a first pole piece, a second pole piece and a separator, and the first tab comprises a first extension part and a second extension part. The first end of the first extension part is electrically connected with the first pole piece, the second end of the first extension part extends along the length direction of the first pole piece, the second end of the first extension part is connected with the first end of the second extension part, and the second end of the second extension part is electrically connected with the shell cover. By arranging the first extension part in the first tab to extend along the length direction of the first pole piece, the force of the first tab on the first pole piece at the connection position can be changed from the width direction to the length direction, the force on the micro crack at the edge of the first pole piece can be effectively reduced to prevent the micro crack from expanding and tearing, the probability of the first pole piece being broken along the width direction can be reduced, and the service life of the electrochemical device is prolonged.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to an electrochemical device and electrical equipment. Background Technology

[0002] A steel-cased button cell battery typically consists of a casing, a cover, and electrode assemblies. The casing houses the electrode assemblies and electrolyte. The electrode assemblies consist of an anode, a cathode, and a separator, which are wound layer by layer in a sequence of "-separator-anode-separator-cathode-". The cathode of the electrode assembly has a first tab, which connects to the cover to conduct the positive polarity. The anode of the electrode assembly has a second tab, which connects to the casing to conduct the negative polarity. The casing and cover are laser-welded to form the battery body.

[0003] However, in existing technologies, the first tab of the cathode electrode assembly is led out directly from one side along the width of the cathode electrode, and the second tab of the anode electrode is led out directly from one side along the width of the anode electrode. In other words, both tabs are led out directly in one direction along the width of the electrode. Under conditions such as drops, impacts, and vibrations, the electrode assembly and the casing will experience relative movement. The first and second tabs will generate stress in the width direction of the current collector on the electrode. Simultaneously, micro-cracks are easily generated at the edges of the anode and cathode electrodes during slitting and cutting. The stress in the width direction can easily cause these cracks to propagate at the cracks, leading to the breakage of the anode and cathode electrodes and a reduction in the battery's energy density. Summary of the Invention

[0004] The main technical problem addressed by this application is to provide an electrochemical device and electrical equipment that can effectively improve the problem that the electrode plates of the electrode assembly are prone to breakage in the width direction.

[0005] The electrochemical device of this application includes a housing, an electrode assembly, and a first tab. The housing includes a shell and a cover, the shell having a receiving cavity, and the cover being connected to the shell to cover the receiving cavity. The electrode assembly is disposed within the receiving cavity and includes a first electrode, a second electrode, and a diaphragm. The first electrode, the diaphragm, and the second electrode are stacked and wound to form a cylindrical electrode assembly, which has a first end face and an opposing second end face. The first tab includes a first extension and a second extension. The first end of the first extension is electrically connected to the first electrode, and the second end of the first extension extends along the length direction of the first electrode and is connected to the first end of the second extension. The second end of the second extension is disposed on the first end face and is electrically connected to the cover.

[0006] In some embodiments, the first extension and the second extension are connected in a near "L" shape.

[0007] In some embodiments, the first electrode tab has a notch located at the corner connection between the first extension and the second extension.

[0008] In some embodiments, along the length direction of the first electrode, the length L1 of the first extension satisfies: 5mm≤L1≤12mm; along the width direction of the first electrode, the width K1 of the first extension satisfies: 3mm≤K1≤10mm.

[0009] In some embodiments, along the width direction of the first electrode, the length L2 of the second extension satisfies: 5mm≤L2≤12mm; along the length direction of the first electrode, the width K2 of the second extension satisfies: 3mm≤K2≤10mm.

[0010] In some embodiments, the first extension and the second extension are connected in a "T" shape. The second extension also has a first reverse end disposed opposite to the second end of the second extension. The first reverse end extends from the first end of the second extension in a direction away from the second end of the second extension, and at least part of the first reverse end is bent and disposed on the second end face. The electrochemical device also includes a first insulating member disposed between the bent first reverse end and the housing.

[0011] In some embodiments, the electrochemical device further includes a second tab, which includes a third extension and a fourth extension. A first end of the third extension is connected to a second electrode, a second end of the third extension extends along the length of the second electrode, and the second end of the third extension is connected to the first end of the fourth extension. The second end of the fourth extension is disposed on a second end face and electrically connected to the housing.

[0012] In some embodiments, the third extension and the fourth extension are connected in a near "L" shape.

[0013] In some embodiments, the third extension and the fourth extension are connected in a "T" shape. The fourth extension is further provided with a second reverse end disposed opposite to the second end of the fourth extension. The second reverse end extends from the first end of the fourth extension in a direction away from the second end of the fourth extension, and at least part of the second reverse end is bent and disposed on the first end face. The electrochemical device also includes a second insulating member disposed between the bent second reverse end and the shell cover.

[0014] To solve the above-mentioned technical problems, another technical solution adopted in the embodiments of this application is to provide an electrical device, including the electrochemical device as described above.

[0015] This application's electrochemical device includes a housing, an electrode assembly, and a first tab. Both the electrode assembly and the first tab are housed inside the housing. The electrode assembly includes a first electrode, a second electrode, and a diaphragm. The first tab includes a first extension and a second extension. A first end of the first extension is electrically connected to the first electrode, and a second end of the first extension extends along the length of the first electrode and connects to the first end of the second extension. The second end of the second extension is electrically connected to the housing cover. By configuring the first extension in the first tab to extend along the length of the first electrode, the force exerted by the first tab on the first electrode at the connection point changes from being oriented towards the width direction to being oriented towards the length direction. This effectively reduces the probability of the first electrode breaking along its width direction due to the relative movement between the electrode assembly and the housing caused by drops or impacts, which could lead to the continued expansion and tearing of small cracks at the edge of the first electrode. This improves the service life of the electrochemical device. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application, the accompanying drawings used in the description of the specific embodiments will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to scale.

[0017] Figure 1 This is an exploded view of the electrochemical device according to an embodiment of this application;

[0018] Figure 2 This is a schematic diagram showing a partial unfolding of the electrode assembly in the electrochemical device of this application embodiment;

[0019] Figure 3 This is an exploded view of the first electrode and the first tab in the electrochemical device of this application embodiment;

[0020] Figure 4 This is a schematic diagram showing the connection between the first electrode and the first tab in the electrochemical device of the first embodiment of this application;

[0021] Figure 5 This is a schematic diagram of the connection between the first electrode and the first tab in the electrochemical device of the second embodiment of this application;

[0022] Figure 6 This is a schematic diagram of the connection between the first electrode and the first tab in the electrochemical device of the third embodiment of this application;

[0023] Figure 7 This is a schematic diagram of the electrode assembly in the electrochemical device according to an embodiment of this application from a first-view perspective;

[0024] Figure 8 This is a schematic diagram of the electrode assembly in the electrochemical device according to an embodiment of this application from a second perspective;

[0025] Figure 9 This is a schematic diagram showing the connection between the first electrode and the first tab in the electrochemical device of the fourth embodiment of this application;

[0026] Figure 10 This is a schematic diagram of the connection between the first electrode and the first tab in the electrochemical device of the fifth embodiment of this application;

[0027] Figure 11 This is a schematic diagram showing the connection between the second electrode and the second tab in the electrochemical device of this application embodiment. Detailed Implementation

[0028] To facilitate understanding of this application, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as "connected" to another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "upper," "lower," "inner," "outer," "vertical," "horizontal," etc., used in this specification indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0029] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the application. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items. Furthermore, technical features involved in the different embodiments of this application described below may be combined with each other as long as they do not conflict with each other.

[0030] Please see Figure 1The electrochemical device 100 includes a housing 10, an electrode assembly 20, a first tab 30, and a second tab 40. The electrode assembly 20, the first tab 30, and the second tab 40 are all located inside the housing 10, which is also filled with an electrolyte (not shown) for the electrochemical reaction to occur in the electrode assembly 20. One end of the first tab 30 is electrically connected to the electrode assembly 20, and the other end is electrically connected to the housing 10 to deflect one polarity of the electrode assembly, such as a positive electrode. One end of the second tab 40 is electrically connected to the electrode assembly 20, and the other end is electrically connected to the housing 10 to deflect the other polarity of the electrode assembly 20, such as a negative electrode. The first and second electrodes formed on the housing 10 are insulated from each other.

[0031] For the aforementioned outer casing 10, please refer to [further details]. Figure 1 The outer casing 10 includes a housing 11 and a cover 12. The housing 11 is generally cylindrical and has a receiving cavity 111 and an opening communicating with the receiving cavity 111. The receiving cavity 111 is used to house the electrode assembly 20, the first electrode tab 30, the second electrode tab 40, and the electrolyte. The cover 12 is connected to the housing 11 to cover the opening, thereby sealing the opening on the housing 11. The first electrode tab 30 is connected to the cover 12 to form a first electrode, and the second electrode tab 40 is connected to the housing 11 to form a second electrode.

[0032] In some embodiments, the housing cover 12 includes an upper cover 121, a composite insulating layer 122, and an electrode post 123. Along the axial direction of the housing 11, the upper cover 121, the composite insulating layer 122, and the electrode post 123 are sequentially stacked. The electrode post 123 is located on the side of the upper cover 121 closest to the receiving cavity 111. The upper cover 121 is welded to the housing 11. The composite insulating layer 122 is used to insulate the electrode post 123 from the upper cover 121. The first electrode tab 30 is electrically connected to the electrode post 123. The upper cover 121 also has a clearance opening 1211 through which a portion of the electrode post 123 extends to the outside to form a first electrode.

[0033] In some embodiments, the bottom of the housing 11 is further provided with a liquid injection hole (not shown), which is used to inject electrolyte into the receiving cavity 111. The bottom of the housing 11 and the opening are disposed opposite to each other along the axial direction of the housing 11. The outer casing 10 also includes a liquid injection plug 13, which is disposed in the liquid injection hole and is used to seal the liquid injection hole to ensure the airtightness of the receiving cavity 111.

[0034] For the electrode assembly 20 described above, please refer to... Figure 2The electrode assembly 20 includes a first electrode 21, a second electrode 22, and a diaphragm 23. The first electrode 21, diaphragm 23, second electrode 22, and diaphragm 23 are stacked sequentially and wound around a winding axis M to form a cylindrical electrode assembly 20. The cylindrical electrode assembly 20 has opposing first end faces 24 and second end faces 25, and insulating adhesive layers 26 are provided on both the first end faces 24 and second end faces 25 to prevent short circuits caused by contact between the first end faces 24 and second end faces 25 and the outer casing 10.

[0035] Please see Figure 3 The first electrode 21 has a first empty foil area 211 and a first welding area 212 at its end along its length direction X, with the first welding area 212 located within the first empty foil area 211. The first electrode tab 30 is partially located within the first empty foil area 211, and the first electrode tab 30 is welded to the first electrode 21 in the first welding area 212, so that the first electrode tab 30 and the first electrode 21 form an electrical connection.

[0036] In some embodiments, the first electrode tab 30 and the first electrode plate 21 can be welded by an ultrasonic welding method. For example, the ultrasonic welding pressure range is set to 0.05-0.3 MPa, the amplitude range is 30%-90%, and the welding energy range is 5-200 J.

[0037] In other embodiments, the first electrode tab 30 and the first electrode plate 21 can be welded by laser welding. For example, the laser power range for laser welding is set to 50%-100%, the laser pulse width is 0-50ms, and the laser welding speed is 50-500mm / s.

[0038] To ensure the stability of the connection between the first electrode tab 30 and the first electrode plate 21, the effective welding area of ​​the first electrode tab 30 and the first electrode plate 21 in the first welding area 212 should be greater than or equal to half the area of ​​the first welding area 212. In addition, the tensile force that the first electrode tab 30 can withstand at the welding point must satisfy F≥5N.

[0039] The second electrode 22 has a second empty foil area and a second welding area at its end along its length, with the second welding area located within the second empty foil area. The second electrode tab 40 is partially located within the second empty foil area, and the second electrode tab 40 is welded to the second electrode 22 in the second welding area, thereby forming an electrical connection between the second electrode tab 40 and the second electrode 22.

[0040] In some embodiments, the second electrode tab 40 and the second electrode plate 22 can be welded by an ultrasonic welding method. For example, the ultrasonic welding pressure range is set to 0.05-0.3 MPa, the amplitude range is 30%-90%, and the welding energy range is 5-200 J.

[0041] In other embodiments, the second electrode tab 40 and the second electrode plate 22 can be welded by laser welding. For example, the laser power range for laser welding is set to 50%-100%, the laser pulse width is 0-50ms, and the laser welding speed is 50-500mm / s.

[0042] To ensure the stability of the connection between the second electrode tab 40 and the second electrode plate 22, the effective welding area of ​​the second electrode tab 40 and the second electrode plate 22 in the second welding area should be greater than or equal to half the area of ​​the second welding area. In addition, the tensile force that the second electrode tab 40 can withstand at the welding point must satisfy F≥5N.

[0043] For the first electrode 30 mentioned above, please refer to Figure 3 The first electrode tab 30 includes a first extension 31 and a second extension 32. The first end of the first extension 31 is welded to the first welding area 212 of the first electrode 21. The second end of the first extension 31 extends along the length direction X of the first electrode 21, and is connected to the first end of the second extension 32. The second end of the second extension 32 is electrically connected to the cover 12. Wherein, the length direction X of the first electrode 21 is the direction in which its long side extends after the first electrode 21 is unfolded, and the width direction Y of the first electrode 21 is the direction perpendicular to its long side after the first electrode 21 is unfolded. Figure 3 As shown; or in the cylindrical wound electrode assembly 20, the length direction X of the first electrode 21 is the winding direction of the first electrode 21, that is, the circumferential direction of the electrode assembly 20, and the width direction Y of the first electrode 21 is approximately parallel to the winding axis M of the electrode assembly 20.

[0044] To ensure that the electrode assembly 20 can be smoothly placed within the receiving cavity 111 of the housing 11 and completely immersed in the electrolyte, a gap exists between the electrode assembly 20 and the housing 10. The electrode assembly 20 is connected to the housing cover 12 via a first tab 30, forming one polarity. The electrode assembly 20 is connected to the housing 11 via a second tab 40, forming the other polarity. During use or transportation of the electrochemical device 100, if the device is dropped or subjected to violent movement, the electrode assembly 20 can move axially or rotate circumferentially relative to the housing 11 within the receiving cavity 111. By configuring the first extension 31 of the first tab 30 to extend along the length direction X of the first electrode 21, the pulling force exerted by the first tab 30 on the first electrode 21 at the welding point is along the length direction X of the first electrode 21. Compared to the design where the first tab 30 extends directly along the width direction Y of the first electrode 21, the tensile force on the first electrode 21 in this application is shifted from the width direction Y to the length direction X. Since the edges of the first electrode 21 are prone to micro-cracks after being cut during manufacturing, changing the direction of the tensile force on the first electrode 21 towards the length direction X effectively reduces the probability of these micro-cracks continuing to expand and tear, thus preventing the first electrode 21 from breaking along the width direction Y.

[0045] It is worth noting that the extension direction of the first extension 31 of the first electrode tab 30 can be approximately parallel to the length direction X of the first electrode 21. In some embodiments, the angle between the extension direction of the first extension 31 and the length direction X of the first electrode 21 can be between 0° and 10°. The connection between the second end of the first extension 31 and the first end of the second extension 32 can be integrally formed or welded.

[0046] Please see Figure 4 In some embodiments, the first extension 31 and the second extension 32 are bent and connected so that the first tab 30 can extend partially approximately toward the length direction X of the first electrode 21, and can also be partially bent and disposed on the first end face 24. Specifically, the included angle R1 between the extension direction of the first extension 31 and the extension direction of the second extension 32 satisfies: 70°≤R1≤150°.

[0047] In some embodiments, please refer to Figure 4 and Figure 5 When the angle R1 between the extending direction of the first extension 31 and the extending direction of the second extension 32 satisfies 80°≤R1≤100°, the first extension 31 and the second extension 32 are approximately "L"-shaped connected, that is, the first extension 31 extends approximately along the length direction X of the first electrode 21, and the second extension 32 extends approximately along the width direction Y of the first electrode 21. Specifically, as... Figure 7 As shown, the first end of the first extension 31 is welded to the first electrode 21, the second end of the first extension 31 is connected to the first end 321 of the second extension 32, the second end 322 of the second extension 32 extends toward the width direction Y of the first electrode 21, and the second end 322 of the second extension 32 is partially bent and disposed on the first end face 24 of the columnar electrode assembly 20, and the second end 322 of the second extension 32 is welded to the electrode post 123 on the shell cover 12.

[0048] Please see Figure 5 In some embodiments, the length L1 of the first extension 31 along the length direction X of the first electrode 21 satisfies: 5mm ≤ L1 ≤ 12mm. If the length of the first extension 31 is too short, the pulling force of the first tab 30 on the first electrode 21 cannot be effectively changed from the width direction Y to the length direction X. If the length of the first extension 31 is too long, it occupies more space in the receiving cavity 111, reducing the energy density of the electrochemical device 100. Therefore, controlling the length of the first extension 31 within a suitable range allows the first extension 31 to both change the direction of the pulling force on the first electrode 21 and to better transition with the housing 11 in the circumferential direction, reducing the probability of the first extension 31 squeezing or scratching the wound first electrode 21. In other embodiments, the length L1 of the first extension 31 satisfies: 6mm ≤ L1 ≤ 9mm.

[0049] Please continue reading. Figure 5 In some embodiments, along the width direction Y of the first electrode 21, the width K1 of the first extension 31 satisfies: 3mm ≤ K1 ≤ 10mm. If the width of the first extension 31 is too small, the rigidity of the first extension 31 is insufficient, and it is prone to breakage; if the width of the first extension 31 is too large, a larger first empty foil area 211 is required, reducing the energy density of the electrochemical device 100. In addition, an excessively wide first extension 31 occupies too much space in the receiving cavity 111, resulting in a reduction in electrolyte capacity and a decrease in the reaction performance of the electrode assembly 20. In other embodiments, the width K1 of the first extension 31 satisfies: 5mm ≤ K1 ≤ 7mm.

[0050] Please continue reading. Figure 5 Along the width direction Y of the first electrode 21, the length L2 of the second extension 32 satisfies: 5mm ≤ L2 ≤ 12mm. Since a portion of the second extension 32 needs to be bent and electrically connected to the first end face 24 of the cylindrical electrode assembly 20, if the length of the second extension 32 is too short, it cannot be bent or will be difficult to connect to the cover 12 after bending; if the length of the second extension 32 is too long, it will exceed the first end face 24. Therefore, it is necessary to control the length of the second extension 32 within a reasonable range. In other embodiments, the length L2 of the second extension 32 satisfies: 8mm ≤ L2 ≤ 10mm.

[0051] Please continue reading. Figure 5 Along the length direction X of the first electrode 21, the width K2 of the second extension 32 satisfies: 3mm ≤ K2 ≤ 10mm. If the width of the second extension 32 is too small, its rigidity is insufficient and it is prone to breakage. If the width of the second extension 32 is too large, it occupies a large space at the bend, wasting space in the receiving cavity 111. Therefore, it is necessary to control the width of the second extension 32 within a reasonable range. In other embodiments, the width K2 of the second extension 32 satisfies: 5mm ≤ K2 ≤ 7mm.

[0052] It is understandable that the first extension 31 and the second extension 32 can be directly cut and integrally formed, or the first extension 31 and the second extension 32 can be formed by welding two independent extensions together.

[0053] Please see Figure 6 In order to avoid excessive stress concentration at the connection corner of the first extension 31 and the second extension 32, which could cause the first extension 31 and the second extension 32 to break, the connection corner of the first extension 31 and the second extension 32 can be arc-shaped.

[0054] Please see Figure 7 and Figure 8 In some embodiments, the first extension 31 and the second extension 32 are generally connected in a "T" shape. That is, as shown... Figure 8 As shown, the second extension 32 also has a first reverse end 323 disposed opposite to the second end 322 of the second extension 32. Along the width direction Y of the first electrode 21, the first reverse end 323 extends from the first end 321 of the second extension 32 in a direction away from the second end 322 of the second extension 32, i.e., the second end 322 of the second extension 32 and the first reverse end 323 are respectively at opposite ends of the first end 321 of the second extension 32. The first reverse end 323 extends toward the second end face 25 of the cylindrical electrode assembly 20, and is partially bent at the second end face 25. The electrochemical device 100 also includes a first insulating member 51, which is disposed between the bent first reverse end 323 and the housing 11, and the bent first reverse end 323 is fixedly connected to the housing 11, for example, by bonding. The first insulating member 51 electrically insulates the bent first reverse end 323 from the housing 11 to prevent short circuits in the electrochemical device 100.

[0055] By arranging the first extension 31 and the second extension 32 in a roughly "T" shape, the second end 322 of the second extension 32 can be bent and disposed on the first end face 24 of the cylindrical electrode assembly 20 and connected and fixed to the cover 12, and the first reverse end 323 can be partially bent and disposed on the second end face 25 of the cylindrical electrode assembly 20 and connected and fixed to the bottom of the housing 11 with insulation, thereby reducing the axial movement of the battery assembly relative to the housing 11 within the receiving cavity 111, and making the force on the second extension 32 in the width direction Y of the first electrode 21 balanced.

[0056] In the embodiment where the first extension 31 and the second extension 32 are generally arranged in a "T" shape, along the width direction Y of the first electrode 21, the length L2 of the second extension 32 satisfies: 10mm ≤ L2 ≤ 20mm, and the length of the first reverse end 323 bent onto the second end face 25 should be greater than or equal to 3mm. It is worth noting that, as... Figure 8 As shown, along the direction perpendicular to the second end face 25, the projection of the first reverse end 323 on the second end face 25 does not overlap with the projection of the second end 422 of the second tab 40 on the second end face 25, thereby preventing the first reverse end 323 from hindering the electrical connection between the second end 422 of the second tab 40 and the bottom of the housing 11.

[0057] In some embodiments, the edge of the first tab 30 is provided with a notch located in the first extension 31 and / or the second extension 32, so that there is a reduced width region in the first extension 31 and / or the second extension 32. The first tab 30 can deform in this reduced width region, thereby further reducing the force transmitted from the outer shell 10 to the first electrode 21 through the first tab 30.

[0058] Please see Figure 9 As one embodiment, the first electrode tab 30 is provided with a first notch 33. The first notch 33 is disposed in the first extension 31 along the width direction Y of the first electrode 21. The first notch 33 is recessed from the edge of the first extension 31 toward the opposite edge of the first extension 31. The position of the first notch 33 is the width reduction area of ​​the first extension 31. The first extension 31 can deflect around the axis perpendicular to the first electrode 21 in this width reduction area.

[0059] In other embodiments, the number of first notches 33 can be one or two. The two first notches 33 are respectively disposed on both sides of the first extension 31 along the length direction X. Further, the two first notches 33 can be symmetrically arranged about the length direction X of the first extension 31.

[0060] In order to enable the first extension 31 to deflect in the region of reduced width, and to ensure the strength of the first extension 31 so that it is not easy to break, the recess depth H of the first notch along the width direction Y of the first electrode 21 satisfies: 0.8mm≤H≤1.5mm.

[0061] Please see Figure 10 In another embodiment, the first tab 30 is provided with a second notch 34, which is located at the corner where the first extension 31 and the second extension 32 connect and is close to the cover 12. The second notch 34 forms a narrower region at the corner, where the first extension 31 and the second extension 32 can be relatively deflected, that is, the included angle between the first extension 31 and the second extension 32 can be changed, thereby giving the first tab 30 deformation characteristics.

[0062] In order to enable the first tab 30 to deflect in the area where the width is reduced, and to ensure that the connection between the first extension 31 and the second extension 32 is not easily broken, a second notch 34 with radius r is formed with the intersection of the extension line of the first extension 31 near the edge of the cover 12 and the extension line of the second extension 32 near the edge of the first extension 31 as the center, wherein the radius r satisfies: 0.8mm≤r≤1.5mm.

[0063] For the second electrode 40 mentioned above, please refer to Figure 2 The second electrode tab 40 includes a third extension 41 and a fourth extension 42. A first end of the third extension 41 is connected to the second electrode 22 to form an electrical connection. A second end of the third extension 41 extends along the length direction X of the second electrode 22 and is connected to the first end of the fourth extension 42. The second end of the fourth extension 42 extends toward the bottom of the housing 11 and is electrically connected to the housing 11 to form the second electrode of the electrochemical device 100. See also... Figure 11 In this context, the length direction X of the second electrode 22 is the direction in which its long side extends after the second electrode 22 is unfolded, and the width direction Y of the second electrode 22 is the direction perpendicular to its long side after the second electrode 22 is unfolded; or in the cylindrical wound electrode assembly 20, the length direction X of the second electrode 22 is the winding direction of the second electrode 22, that is, the circumferential direction of the electrode assembly 20, and the width direction Y of the second electrode 22 is approximately parallel to the winding axis M of the electrode assembly 20.

[0064] It is worth noting that the extension direction of the third extension 41 of the second electrode tab 40 can be approximately parallel to the length direction X of the second electrode 22. In some embodiments, the angle between the extension direction of the third extension 41 and the length direction X of the second electrode 22 can be between 0° and 10°.

[0065] In some embodiments, please refer to Figure 11 The third extension 41 and the fourth extension 42 are bent and connected so that the second electrode tab 40 can extend partially toward the length direction X of the second electrode 22 and can also be bent and disposed on the first end face 24. Specifically, the angle R2 between the extension direction of the third extension 41 and the extension direction of the fourth extension 42 satisfies: 70°≤R2≤150°.

[0066] In some embodiments, please refer to Figure 11 When the angle R2 between the extension direction of the third extension 41 and the extension direction of the fourth extension 42 satisfies 80°≤R2≤100°, the third extension 41 and the fourth extension 42 are approximately "L"-shaped connected, that is, the third extension 41 extends approximately along the length direction X of the second electrode 22, and the fourth extension 42 extends approximately along the width direction Y of the second electrode 22. Specifically, as... Figure 8 As shown, the first end of the third extension 41 is welded to the second electrode 22, the second end of the third extension 41 is connected to the first end 421 of the fourth extension 42, the second end 422 of the fourth extension 42 extends toward the width direction Y (reverse) of the second electrode 22, and a portion of the second end 422 of the fourth extension 42 is bent and disposed on the second end face 25 of the columnar electrode assembly 20, and the bent second end 422 of the fourth extension 42 is welded to the housing 11.

[0067] In some embodiments, please refer to Figure 7 and Figure 8 The third extension 41 and the fourth extension 42 are generally connected in a "T" shape. That is, the fourth extension 42 also has a second reverse end 423 disposed opposite to the second end 422 of the fourth extension 42. Along the width direction Y of the second electrode 22, the second reverse end 423 extends from the first end 421 of the fourth extension 42 in a direction away from the second end 422 of the fourth extension 42. That is, the second end 422 and the second reverse end 423 of the fourth extension 42 are respectively located at opposite ends of the first end 421 of the fourth extension 42. Figure 7 As shown, the second reverse end 423 extends toward the first end face 24 of the cylindrical electrode assembly 20, and a portion of the second reverse end 423 is bent and disposed on the first end face 24. The electrochemical device 100 also includes a second insulating member 52, which is disposed between the bent second reverse end 423 and the housing cover 12, and the bent second reverse end 423 is fixedly connected to the housing cover 12, for example, by bonding. The second insulating member 52 electrically insulates the bent second reverse end 423 from the housing cover 12 to prevent short circuit of the electrochemical device 100.

[0068] By arranging the third extension 41 and the fourth extension 42 in a roughly "T" shape, the second end 422 of the fourth extension 42 can be bent and disposed on the second end face 25 of the cylindrical electrode assembly 20 and connected and fixed to the housing 11, and the second reverse end 423 can be partially bent and disposed on the first end face 24 of the cylindrical electrode assembly 20 and insulatedly connected and fixed to the cover 12, thereby reducing the axial movement of the battery assembly relative to the housing 11 within the receiving cavity 111, and balancing the force on the fourth extension 42 in the width direction Y of the second electrode 22.

[0069] It is worth noting that the structure of the second electrode 40 in this application is similar to that of the first electrode 30. Other structures of the second electrode 40 not mentioned in this application can be referred to the structure of the first electrode 30, which will not be elaborated here.

[0070] This application also provides embodiments of an electrical device, which includes the electrochemical device 100 described above. For details regarding the specific structure and function of the electrochemical device 100, please refer to the above embodiments; further details will not be repeated here.

[0071] The electrochemical device 100 of this application includes a housing 10, an electrode assembly 20, and a first tab 30. Both the electrode assembly 20 and the first tab 30 are housed inside the housing 10. The electrode assembly 20 includes a first electrode 21, a second electrode 22, and a diaphragm 23. The first tab 30 includes a first extension 31 and a second extension 32. A first end of the first extension 31 is electrically connected to the first electrode 21, and a second end of the first extension 31 extends along the length direction X of the first electrode 21, and the second end of the first extension 31 is connected to the first end of the second extension 32. The second end of the second extension 32 is electrically connected to the cover 12 of the housing 10. By configuring the first extension 31 in the first tab 30 to extend along the length direction X of the first electrode 21, the force exerted by the first tab 30 on the first electrode 21 at the connection point can be changed from the width direction Y to the length direction X. This can effectively reduce the probability that the relative movement between the electrode assembly 20 and the housing 10 will cause the small cracks at the edge of the first electrode 21 to continue to expand and tear under stress in the event of a drop or impact on the electrochemical device 100, thereby causing the first electrode 21 to break along the width direction Y, and improve the service life of the electrochemical device 100.

[0072] To facilitate understanding of the technical solution and beneficial effects of the electrochemical device in the embodiments of this application, a steel-cased button battery is used as an example for explanation below.

[0073] A steel-cased button cell battery includes a casing, electrode assembly, a positive electrode tab, a negative electrode tab, and an electrolyte. The electrode assembly, positive electrode tab, negative electrode tab, and electrolyte are housed inside the casing. The casing includes a cover and a housing, with the cover insulated from the housing. The electrode assembly includes a positive electrode plate, a negative electrode plate, and a separator. The positive electrode plate, separator, negative electrode plate, and separator are stacked sequentially and then wound to form a cylindrical electrode assembly. One end of the positive electrode tab is welded to the longitudinal end of the positive electrode plate, and the other end of the positive electrode tab is bent at the first end face of the cylindrical electrode assembly and welded to the cover. The cover forms the positive electrode of the steel-cased button cell battery. One end of the negative electrode tab is welded to the longitudinal end of the negative electrode plate, and the other end of the negative electrode tab is bent at the second end face of the cylindrical electrode assembly and welded to the housing. The housing forms the negative electrode of the steel-cased button cell battery.

[0074] 1. Test methods and equipment:

[0075] (1) Set the ambient temperature to 25℃;

[0076] (2) Pre-treatment of steel-cased button batteries: First, let them stand for 5 minutes, then discharge them to 3.0V with constant current (50mA), let them stand for 5 minutes, then charge them to 3.9V with constant current (500mA), and finally let them stand for 5 minutes.

[0077] (3) Drop test on steel-cased button batteries: The steel-cased button batteries of the comparative example and the embodiment are placed in the roller test fixture and then placed in the roller test device. The roller conditions are set as follows: the steel-cased button battery is dropped from a height of 1m and dropped 2500 times at a speed of 7 revolutions / min (2 drops are counted as 1 revolution).

[0078] (4) Measurement of steel-cased button batteries: Voltage and internal resistance were measured using 1KHz specification. After the steel-cased button batteries completed 2500 drop tests, the voltage and internal resistance of the steel-cased button batteries were tested and the test results were recorded.

[0079] Example

[0080] [Preparation of the positive electrode plate]

[0081] Lithium cobalt oxide (LCO, with an average particle size of 8 μm, obtained by sieving), PVDF, and conductive carbon black (SP) were mixed at a mass ratio of 97:1.5:1.5. NMP was added as a solvent to prepare a positive electrode active material slurry with a solid content of 75 wt%, and the mixture was stirred evenly. The positive electrode active material layer was uniformly coated onto the surface of the positive electrode current collector aluminum foil using a coating process, and then dried at 90°C to obtain a positive electrode active material layer with a thickness of 120 μm. The above steps were then repeated on the other side of the aluminum foil to obtain a positive electrode sheet with positive electrode active material layers coated on both sides. The obtained positive electrode sheet was then cold-pressed, slit, and cut to obtain the positive electrode wafer.

[0082] [Preparation of the negative electrode]

[0083] Artificial graphite, conductive carbon black (SP), styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 97:1:1:1, and deionized water was added to prepare a slurry with a solid content of 75 wt%, which was then stirred evenly. The slurry was uniformly coated onto one surface of a 6 μm thick copper foil used as a negative electrode current collector and dried at 85°C to obtain a 120 μm thick negative electrode active material layer. The above steps were then repeated on the other surface of the copper foil to obtain a negative electrode sheet with double-sided negative electrode active material coating. The obtained negative electrode sheet was then cold-pressed, slit, and cut to obtain the final negative electrode sheet.

[0084] Preparation of Electrolyte

[0085] Ethylene carbonate, propylene carbonate, diethyl carbonate, propyl propionate, and vinylene carbonate were mixed in a mass ratio of 20:30:20:28:2 to obtain a non-aqueous organic solvent. Then, lithium salt LiPF6 was mixed with the non-aqueous organic solvent in a mass ratio of 8:92 to prepare the electrolyte.

[0086] [Preparation of the diaphragm]

[0087] A porous polyethylene film with a thickness of 7μm is used.

[0088] [Preparation of Steel-Cased Button Batteries]

[0089] The positive electrode sheet is partially removed from the end along the length direction to expose the aluminum foil. The positive electrode tab includes a first extension and a second extension. The first end of the first extension is welded to the aluminum foil. The second end of the first extension extends along the length direction of the positive electrode sheet and is connected to the first end of the second extension. The second end of the second extension is bent and disposed on the first end face of the electrode assembly. The first extension and the second extension are connected in an approximately L-shape.

[0090] The negative electrode sheet is partially removed from the end along the length direction to expose the copper foil. The negative electrode tab includes a third extension and a fourth extension. The first end of the third extension is welded to the copper foil. The second end of the third extension extends along the length direction of the negative electrode sheet and is connected to the first end of the fourth extension. The second end of the fourth extension is bent and disposed on the second end face of the electrode assembly. The third extension and the fourth extension are connected in an approximately L-shape.

[0091] The positive electrode, separator, and negative electrode prepared above are stacked and wound to form a wound cylindrical electrode assembly, with the separator positioned between the positive and negative electrode to act as a separator. Insulating adhesive layers are provided on both ends of the cylindrical electrode assembly. The electrode assembly is placed in a cylindrical casing. The second end of the second extension in the positive electrode tab is welded to the casing cover, and the second end of the fourth extension in the negative electrode tab is welded to the casing. After drying, electrolyte is injected, and the steel-cased button battery is obtained through vacuum sealing, settling, formation, and degassing processes.

[0092] Comparative Example: Except for the difference in the structure of the positive electrode tab and the structure of the negative electrode tab in the preparation of the steel-cased button battery compared with the example, the other parameters remain the same. Specifically, the positive electrode tab is set to extend directly along the width direction of the positive electrode sheet after being welded to the positive electrode sheet, and the negative electrode tab is set to extend directly along the width direction of the negative electrode sheet after being welded to the negative electrode sheet.

[0093] It is worth noting that, in order to facilitate data collection and ensure data reliability, the number of steel-cased button batteries used in the experiments of the examples and comparative examples should be three or more. In this experiment, the number of steel-cased button batteries used in the examples and comparative examples was three. In the examples, the batteries were numbered 1, 2, and 3 in sequence, and in the comparative examples, the batteries were numbered 4, 5, and 6 in sequence. The experimental results are shown in Table 1.

[0094] Table 1

[0095]

[0096] Note: Infinite internal resistance of the battery indicates that the positive tab is broken from the positive electrode plate, and / or the negative tab is broken from the negative electrode plate, and the battery loses its power supply capability.

[0097] Conclusion: Based on the embodiments and comparative examples, it can be seen that setting the positive electrode tab as the first extension extending along the length direction of the positive electrode sheet and setting the negative electrode tab as the third extension extending along the length direction of the negative electrode sheet can effectively reduce the risk of the positive and negative electrode sheets being torn and broken, and improve the service life and reliability of the steel-cased button battery.

[0098] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. An electrochemical device, characterized in that, include: An outer casing includes a housing and a cover, the housing having a receiving cavity, and the cover being connected to the housing to cover the receiving cavity; An electrode assembly, disposed within the receiving cavity, includes a first electrode, a second electrode, and a diaphragm. The first electrode, diaphragm, and second electrode are stacked and wound to form a cylindrical electrode assembly. The cylindrical electrode assembly has a first end face and opposing second end faces. The first electrode tab is independent of the first electrode plate. The first electrode tab includes a first extension and a second extension. The first end of the first extension is welded to the first electrode plate. The second end of the first extension extends along the length direction of the first electrode plate and is connected to the first end of the second extension. The second end of the second extension is disposed on the first end face and is electrically connected to the shell cover. Along the winding axis of the electrode assembly, the width of the first extension is smaller than the width of the first electrode sheet.

2. The electrochemical device according to claim 1, characterized in that, The first extension and the second extension are connected in a near "L" shape.

3. The electrochemical device according to claim 2, characterized in that, The first electrode tab has a notch, which is located at the corner connection between the first extension and the second extension.

4. The electrochemical device according to claim 2, characterized in that, Along the length direction of the first electrode, the length L1 of the first extension satisfies: 5mm≤L1≤12mm; Along the width direction of the first electrode, the width K1 of the first extension satisfies: 3mm≤K1≤10mm.

5. The electrochemical device according to claim 2, characterized in that, Along the width direction of the first electrode, the length L2 of the second extension satisfies: 5mm≤L2≤12mm; Along the length direction of the first electrode, the width K2 of the second extension satisfies: 3mm≤K2≤10mm.

6. The electrochemical device according to claim 1, characterized in that, The first extension and the second extension are connected in a "T" shape. The second extension also has a first reverse end disposed opposite to the second end of the second extension. The first reverse end extends from the first end of the second extension in a direction away from the second end of the second extension, and at least part of the first reverse end is bent and disposed on the second end face. The electrochemical device also includes a first insulating member disposed between the bent first reverse end and the housing.

7. The electrochemical device according to any one of claims 1-6, characterized in that, The electrochemical device further includes a second tab, which includes a third extension and a fourth extension. The first end of the third extension is connected to the second electrode, and the second end of the third extension extends along the length direction of the second electrode. The second end of the third extension is connected to the first end of the fourth extension, and the second end of the fourth extension is disposed on the second end face and electrically connected to the housing.

8. The electrochemical device according to claim 7, characterized in that, The third extension and the fourth extension are connected in a near "L" shape.

9. The electrochemical device according to claim 7, characterized in that, The third extension and the fourth extension are connected in a "T" shape. The fourth extension is also provided with a second reverse end disposed opposite to the second end of the fourth extension. The second reverse end extends from the first end of the fourth extension in a direction away from the second end of the fourth extension, and at least part of the second reverse end is bent and disposed on the first end face. The electrochemical device also includes a second insulating member disposed between the bent second reverse end and the shell cover.

10. An electrical appliance, characterized in that, Includes the electrochemical device as described in any one of claims 1-9.

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