Cylindrical battery and electric equipment

Abstract

The invention provides a cylindrical battery and electric equipment, the cylindrical battery comprises an electrode assembly and gummed paper, the electrode assembly is of a winding type structure and is provided with a winding center line, the electrode assembly comprises a first pole piece and a first pole lug, the outermost ring of the first pole piece is connected with the first pole lug, and the first pole piece is provided with a winding ending end; the gummed paper comprises a first part and a second part, the first part is attached to the first pole piece, and the second part is attached to the first tab; in the winding direction of the electrode assembly, the second part comprises a first side and a second side which are oppositely arranged, compared with the first side, the second side is closer to the winding ending end, and the first part is located on the first side; observed from the extending direction of the winding center line, the connecting line of the end, close to the second part, of the first part and the winding center is defined as a first virtual line, the connecting line of the end, away from the second part, of the first part and the winding center is defined as a second virtual line, and the included angle between the first virtual line and the second virtual line is not smaller than 10 degrees; and the possibility of welding edge breakage is reduced.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a cylindrical battery and an electrical device. Background Art

[0002] Currently, cylindrical batteries typically consist of an electrode assembly and a casing. The electrode assembly is housed within the casing and includes a positive electrode sheet, a positive tab, a negative electrode sheet, and a negative tab. The positive electrode sheet and the positive tab are welded together, while the negative electrode sheet and the negative tab are welded together. During the charge and discharge process of a cylindrical battery, the volume of the electrode assembly repeatedly expands and contracts, causing repeated tension on the weld edges between the negative electrode sheet and the negative tab, which can easily break the weld edges and cause the cylindrical battery to fail. Summary of the Invention

[0003] The embodiments of the present application provide a cylindrical battery and an electrical device to reduce the possibility of weld edge breakage.

[0004] In a first aspect, an embodiment of the present application provides a cylindrical battery, comprising an electrode assembly, wherein the electrode assembly is a wound structure, the electrode assembly has a winding centerline, the electrode assembly comprises a first electrode sheet and a first electrode tab, the outermost circle of the first electrode sheet is connected to the first electrode tab, and the first electrode sheet has a winding tail end; The adhesive tape includes a first portion and a second portion connected to each other, the first portion being attached to the first electrode sheet and the second portion being attached to the first electrode tab; the second portion includes a first side and a second side oppositely disposed along the winding direction of the electrode assembly, the second side being closer to the winding end than the first side, and the first portion being located on the first side; Observed from the extension direction of the winding centerline, the line connecting the end of the first part close to the second part and the winding center is defined as the first virtual line, and the line connecting the end of the first part away from the second part and the winding center is defined as the second virtual line. The angle between the first virtual line and the second virtual line is α, and α≥10°.

[0005] In this cylindrical battery, adhesive tape is applied between the first electrode sheet and the first tab. During charge-discharge cycle testing, the tape distributes the pulling force on the first electrode sheet, thereby reducing the strain on the weld and lowering the risk of the first electrode sheet breaking at the weld edge. Setting α ≥ 10° can reduce the possibility of adhesive failure caused by a small adhesive area between the first portion and the first electrode sheet, and better distribute the pulling force on the first electrode sheet.

[0006] In some embodiments of the first aspect of the present application, along the winding direction of the electrode assembly, the length L2 of the second portion satisfies: 1 mm ≤ L2 ≤ W; wherein W is the width of the first electrode tab along the winding direction of the electrode assembly.

[0007] In one or more of the above optional embodiments, setting 1mm≤L2 can reduce the possibility of adhesion failure caused by the small adhesion area between the second part and the first tab, which is beneficial to improving the bonding stability between the tape and the first tab; setting L2≤W, that is, the maximum length of the second part is the width of the first tab along the winding direction of the electrode assembly, so as to achieve the attachment of the second part to the first tab as a whole and reduce the possibility of the second part being suspended relative to the first tab.

[0008] In some embodiments of the first aspect of the present application, the first pole piece of the outermost circle includes a coating area and a hollow foil area, the winding end is one end of the hollow foil area, and the first pole ear is connected to the hollow foil area.

[0009] In one or more optional embodiments above, the first tab is connected to the empty foil area of ​​the outermost circle of the first pole piece, so that the welding point between the first tab and the first pole piece is located at the outermost circle of the first pole piece to facilitate the bonding of the adhesive tape.

[0010] In some embodiments of the first aspect of the present application, along the winding direction of the electrode assembly, the length of the empty foil area between the first electrode tab and the coating area is A, the length of the first part is L1, and L1 ≥ A / 3. In one or more of the above optional embodiments, setting L1≥A / 3 can reduce the possibility of adhesion failure caused by a small adhesion area between the first part and the first electrode, which is beneficial to improving the bonding stability between the tape and the first electrode.

[0011] In some embodiments of the first aspect of the present application, the cylindrical battery further includes a housing, and the electrode assembly is accommodated in the housing; Along the winding direction of the electrode assembly, the length of the first portion is L1, the length of the second portion is L2, the circumference of the inner circumference of the shell is C, the length of the adhesive tape is L, and L1+L2≤L≤C.

[0012] In one or more of the above optional embodiments, a shell is provided to accommodate the motor assembly; L1+L2≤L is set, that is, the minimum length of the adhesive tape is the sum of the length of the first part and the length of the second part. When L>L1+L2, the part of the adhesive tape exceeding the first part and the second part can be attached to the side of the second part close to the winding end to improve the bonding stability of the adhesive tape; L≤C is set, that is, the maximum length of the adhesive tape is not greater than the inner circumference of the shell, which can reduce the impact on assembly. In some embodiments of the first aspect of the present application, the cylindrical battery further includes a housing, and the electrode assembly is accommodated in the housing; The elongation δ of the adhesive tape satisfies: δ≥1.2×((2πR-2πr) / 2πr), where R is the inner radius of the shell, π is pi, and r is the radius of the electrode assembly.

[0013] In one or more of the above optional embodiments, setting δ≥1.2×((2πR-2πr) / 2πr) can reduce the possibility of the adhesive tape breaking while achieving the distribution of the pulling force. In some embodiments of the first aspect of the present application, along the extension direction of the winding centerline, the width of the first pole piece is H, the width of the adhesive tape is h, and 0.2H≤h≤H.

[0014] In one or more optional embodiments above, setting 0.2H≤h can reduce the possibility of less force sharing due to the tape being too narrow; setting h≤H can reduce the possibility of the tape being too wide affecting the assembly of the bare cell. In some embodiments of the first aspect of the present application, the thickness t of the adhesive tape satisfies: 0.01 mm ≤ t ≤ 0.1 mm.

[0015] In one or more of the above optional embodiments, setting 0.01mm≤t can reduce the possibility of less force sharing due to the adhesive tape being too thin; setting t≤0.1mm can reduce the possibility of difficulty in assembly due to the adhesive tape being too thick affecting the diameter of the bare battery cell. In some embodiments of the first aspect of the present application, the adhesive tape is located on a side of the first pole piece away from the winding center line.

[0016] In one or more of the above optional embodiments, adhesive tape is provided on the outermost side of the first pole piece to facilitate bonding. In some embodiments of the first aspect of the present application, the adhesive tape includes a base material layer and an adhesive layer, and the peel strength between the adhesive layer and the first pole piece is F, 0.5 N / mm≤F≤10 N / mm.

[0017] In one or more of the above optional embodiments, 0.5 N / mm≤F≤10 N / mm is set to ensure the bonding strength between the adhesive tape and the first pole piece. In some embodiments of the first aspect of the present application, the adhesive layer includes acrylic resin adhesive, polyimide adhesive, or silicone-fluororubber composite system adhesive.

[0018] In one or more optional embodiments above, the adhesive layer is provided to include one of acrylic resin adhesive, polyimide adhesive or silicone-fluororubber composite adhesive to achieve its bonding properties.

[0019] In some embodiments of the first aspect of the present application, the material of the substrate layer is polypropylene, polyethylene terephthalate or polyimide.

[0020] In one or more optional embodiments above, the material of the substrate layer is one of polypropylene, polyethylene terephthalate or polyimide to achieve the ductility of the adhesive tape.

[0021] In some embodiments of the first aspect of the present application, the first electrode tab and the first electrode piece are welded to form a welding area, and the second portion at least partially covers the welding area.

[0022] In one or more of the above optional embodiments, the second portion is provided to at least partially cover the welding area, which can reduce the pulling on the welding point and reduce the risk of fracture at the welding edge. In some embodiments of the first aspect of the present application, the adhesive tape also includes a third part, the first part, the second part and the third part are connected in sequence, the third part is attached to the first electrode sheet, and the third part is located on the second side along the winding direction of the electrode assembly.

[0023] In one or more of the above optional embodiments, by providing a third part, the adhesive tape can cover the entire welding area, which can not only improve the bonding stability, but also cover the burrs generated at the welding point, thereby reducing the negative impact of the burrs on battery performance.

[0024] In some embodiments of the first aspect of the present application, the electrode assembly further includes a second pole piece and a second pole lug, the second pole piece has opposite polarity to the first pole piece, the outermost circle of the first pole piece is located outside the outermost circle of the second pole piece, and the second pole lug is connected to the second pole piece.

[0025] In one or more optional embodiments above, a second pole piece having a polarity opposite to that of the first pole piece is provided, and a second pole lug connected to the second pole piece is provided to form an electrode assembly.

[0026] In some embodiments of the first aspect of the present application, the first electrode is a negative electrode. In one or more of the above optional embodiments, the first electrode sheet is set as a negative electrode sheet, and correspondingly, the first electrode tab is a negative electrode tab, so that the adhesive tape can be attached to the negative electrode sheet and the negative electrode tab, and the pulling force on the negative electrode sheet is distributed by the adhesive tape, thereby reducing the risk of the negative electrode sheet breaking at the welding edge.

[0027] In a second aspect, an embodiment of the present application provides an electrical device, which includes the cylindrical battery provided by any embodiment of the first aspect.

[0028] In one or more optional embodiments above, the cylindrical battery provided in any embodiment of the first aspect has good safety performance, so that the electrical equipment powered by the cylindrical battery has good power safety and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope.

[0030] Figure 1 Schematic diagram of the cross-sectional structure of a cylindrical battery in some embodiments of the present application; Figure 2 This is a schematic structural diagram of some embodiments of the present application in which the first electrode sheet is flattened and connected to the first electrode tab and the adhesive tape; Figure 3 This is another schematic cross-sectional structure diagram of a cylindrical battery in some embodiments of the present application; Figure 4 This is a schematic diagram of the structure of electrical equipment in some implementations of this application.

[0031] icon: 1000. Electrical equipment; 100. Cylindrical battery; 10. Electrode assembly; 11. First pole piece; 11a. Winding end; 11b. Coating area; 11c. Empty foil area; 111. First current collector; 112. First active material layer; 12. Second pole piece; 13. Separator; 14. First tab; 20. Adhesive tape; 21. First portion; 22. Second portion; 22a. First side; 22b. Second side; 23. Third portion; x, the winding direction of the electrode assembly; z, the extension direction of the winding centerline of the electrode assembly. DETAILED DESCRIPTION

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Generally, the components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application as claimed, but is merely representative of selected embodiments of the present application. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0035] In the description of the embodiments of the present application, it should be noted that the indicated orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the product of the application is conventionally placed when in use, or are the orientations or positional relationships conventionally understood by those skilled in the art. These are merely for the convenience of describing the present application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present application. In addition, the terms "first," "second," "third," etc. are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0036] Currently, market developments indicate that batteries are becoming increasingly widespread. They are used in a wide range of electric vehicles, including electric bicycles, electric motorcycles, and electric vehicles, as well as in power tools, drones, and energy storage devices. As battery applications continue to expand, market demand is also growing.

[0037] As a type of battery, cylindrical batteries include an electrode assembly and a shell. The shell includes a shell and a shell cover. The electrode assembly is accommodated in the shell. The electrode assembly includes a positive electrode sheet, a positive electrode tab, a negative electrode sheet and a negative electrode tab. The positive electrode sheet is welded to the positive electrode tab, and the negative electrode sheet is welded to the negative electrode tab. At the same time, the positive electrode tab is welded to the shell, and the negative electrode tab is welded to the negative electrode post or shell cover.

[0038] During the charge and discharge process of cylindrical batteries, the volume of the electrode assembly repeatedly expands and contracts, causing repeated tension on the weld edge between the negative electrode tab and the negative electrode tab. Ultrasonic welding is typically used to weld the negative electrode tab, which has initial wear and tear. This can easily lead to fractures in the weld edge after the tension, causing the cylindrical battery to fail.

[0039] To reduce the possibility of weld edge fracture, existing techniques typically involve reducing the thickness of the negative electrode tab or increasing the thickness of the negative electrode sheet. Reducing the thickness of the negative electrode tab reduces its thickness, weakening its structural strength and making it more susceptible to deformation due to strain. This reduces stress and the likelihood of fracture, but reducing the thickness of the negative electrode tab will not meet overcurrent requirements. Increasing the thickness of the negative electrode sheet, on the other hand, results in a loss of energy density.

[0040] Based on the above considerations, and to reduce the possibility of weld edge fracture, an embodiment of the present application provides a cylindrical battery comprising an electrode assembly and adhesive tape. The electrode assembly is a wound structure having a winding centerline. The electrode assembly comprises a first electrode sheet and a first tab. The outermost ring of the first electrode sheet is connected to the first tab, and the first electrode sheet has a winding end. The adhesive tape comprises a first portion and a second portion, wherein the first portion is attached to the first electrode sheet and the second portion is attached to the first tab. Along the winding direction of the electrode assembly, the second portion comprises a first side and a second side disposed opposite each other, wherein the second side is closer to the winding end than the first side, and the first portion is located on the first side.

[0041] By attaching adhesive tape between the first electrode sheet and the first electrode tab, the pulling force on the first electrode sheet can be distributed by the adhesive tape during the charge and discharge cycle test, thereby reducing the pulling on the welding point, reducing the risk of the first electrode sheet breaking at the welding edge, and further improving the safety performance of the cylindrical battery.

[0042] The present invention provides an electrical device that uses a cylindrical battery as a power source. The electrical device may include, but is not limited to, a power tool, an electric vehicle, an unmanned aerial vehicle, or an energy storage device. The power tool may include an electric drill, an electric saw, and the like, and the electric vehicle may include an electric car, an electric motorcycle, or an electric bicycle.

[0043] The following further describes the embodiments of the present application in conjunction with the accompanying drawings. In the accompanying drawings, the winding direction x of the electrode assembly corresponds to the length direction of the first and second electrode sheets in a flattened state, and the extension direction z of the winding centerline of the electrode assembly corresponds to the width direction of the first and second electrode sheets in a flattened state.

[0044] See also Figure 1 and Figure 2 The embodiment of the present application provides a cylindrical battery 100, including a cylindrical shell (not shown), an electrode assembly 10 and a tape 20, wherein the electrode assembly 10 is accommodated in the shell.

[0045] In some embodiments, the housing is a flexible packaging bag, such as an aluminum-plastic film. In other embodiments, the housing is a hard housing, such as a plastic housing, or a metal housing comprising at least one of a steel alloy, an aluminum alloy, and a copper alloy.

[0046] In some embodiments, as Figure 1 As shown, the electrode assembly 10 includes a first electrode sheet 11, a second electrode sheet 12, a separator 13, a first electrode tab 14 and a second electrode tab (not shown). The first electrode sheet 11, the separator 13 and the second electrode sheet 12 are stacked and wound to form a wound structure.

[0047] In some embodiments, as Figure 1As shown, the first pole piece 11 includes a first current collector 111 and a first active material layer 112 disposed on the first current collector 111. The second pole piece 12 includes a second current collector and a second active material layer disposed on the second current collector.

[0048] In some embodiments, the first electrode sheet 11 is a positive electrode sheet, the first current collector 111 is a positive electrode current collector, and the first active material layer 112 is a positive electrode active material layer; the second electrode sheet 12 is a negative electrode sheet, the second current collector is a negative electrode current collector, and the second active material layer is a negative electrode active material layer. In other embodiments, the first electrode sheet 11 is a negative electrode sheet, the first current collector 111 is a negative electrode current collector, and the first active material layer 112 is a negative electrode active material layer; the second electrode sheet 12 is a positive electrode sheet, the second current collector is a positive electrode current collector, and the second active material layer is a positive electrode active material layer.

[0049] In some embodiments, at least one of the positive electrode current collector and the negative electrode current collector is a metal layer. As an illustrative example, the positive electrode current collector may be a metal layer comprising at least one of aluminum, nickel, tantalum, and titanium, such as aluminum foil. The negative electrode current collector may be a metal layer comprising at least one of copper, nickel, tantalum, and titanium, such as copper foil. In other embodiments, at least one of the positive electrode current collector and the negative electrode current collector is a composite current collector.

[0050] In some embodiments, the positive electrode active material includes at least one of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese iron phosphate, or lithium manganese oxide.

[0051] In some embodiments, the negative electrode active material includes at least one of graphite, hard carbon, soft carbon, silicon, silicon-oxygen material, and silicon-carbon material.

[0052] In some embodiments, the isolation film 13 is made of insulating film materials such as polyethylene film, polypropylene film, polyester film, or polyimide film.

[0053] In some embodiments, the cylindrical battery 100 further includes an electrolyte (not shown), which is contained in the housing.

[0054] In some embodiments, the electrolyte comprises a lithium salt and a solvent. The lithium salt may be lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium trifluoromethanesulfinate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiN(SO2CF3)2), lithium tris(trifluoromethylsulfonyl)methyl (LiC(SO2CF3)3), or lithium bis(oxalatoborate) (LiBOB). The solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or combinations thereof.

[0055] In some embodiments, see Figure 1 and Figure 2The outermost circle of the first pole piece 11 is connected to the first pole tab 14 , and the first pole piece 11 has a winding tail end 11 a .

[0056] The adhesive tape 20 includes a first portion 21 and a second portion 22. The first portion 21 is attached to the first electrode sheet 11, and the second portion 22 is attached to the first electrode tab 14. Along the winding direction x of the electrode assembly 10, the second portion 22 includes a first side 22a and a second side 22b that are oppositely disposed. Compared to the first side 22a, the second side 22b is closer to the winding end 11a. The first portion 21 is located on the first side 22a.

[0057] Observed from the extension direction z of the winding center line, the line connecting the end of the first part 21 close to the second part 22 and the winding center O is defined as the first virtual line s1, and the line connecting the end of the first part 21 away from the second part 22 and the winding center O is defined as the second virtual line s2. The angle between the first virtual line s1 and the second virtual line s2 is α, and α≥10°.

[0058] Illustratively, the winding center O is located on the winding center line of the electrode assembly 10 .

[0059] The measurement / calculation formula for the angle α between the first virtual line s1 and the second virtual line s2 can be: α=(L1 / 2πr)×360°, where L1 is the length of the first part 21 and r is the radius of the electrode assembly 10. Therefore, the formula can be understood as the length of the first part 21 of the adhesive tape 20 divided by the outer circumference of the electrode assembly 10, and then multiplied by 360° to obtain the angle α.

[0060] In the embodiment of the present application, the value of π is 3.14.

[0061] In the embodiments of the present application, the radius r of the electrode assembly 10 refers to the outer radius of the electrode assembly 10. The outer radius of the electrode assembly 10 is measured by scanning the cylindrical battery 100 using a computed tomography (CT) device. A circumscribed circle is obtained based on the outer contour of the electrode assembly 10. The center of the circumscribed circle is the winding center O, and the winding centerline passes through the winding center O. The diameter of the circumscribed circle is the outer diameter of the electrode assembly 10, and half the length of the outer diameter is the outer radius. The thickness of the first tab 14 must be included in the outer diameter measurement.

[0062] In this cylindrical battery, adhesive tape 20 is attached between the first electrode sheet 11 and the first tab 14. During charge-discharge cycle testing, the pulling force applied to the first electrode sheet 11 can be distributed by the adhesive tape 20, thereby reducing the pulling force on the weld and lowering the risk of the first electrode sheet 11 breaking at the weld edge. Setting α ≥ 10° can reduce the possibility of adhesive failure caused by a small adhesive area between the first portion 21 and the first electrode sheet 11, and is more conducive to distributing the pulling force applied to the first electrode sheet 11.

[0063] In some embodiments, see Figure 1 Along the winding direction x of the electrode assembly 10 , the length L2 of the second portion 22 satisfies: 1 mm ≤ L2 ≤ W. Wherein W is the width of the first electrode tab 14 along the winding direction x of the electrode assembly 10 .

[0064] It should be noted that Figure 1 The case of L2=W is shown. In other embodiments, see Figure 3 , the length L2 of the second portion 22 of the adhesive tape 20 may also satisfy 1mm≤L2<W.

[0065] By setting 1mm≤L2, the possibility of adhesive failure caused by a small adhesion area between the second portion 22 and the first tab 14 can be reduced, thereby improving the adhesive stability between the adhesive tape 20 and the first tab 14. By setting L2≤W, that is, the maximum length of the second portion 22 is equal to the width of the first tab 14 along the winding direction x of the electrode assembly 10, the entire second portion 22 can be attached to the first tab 14, reducing the possibility of the second portion 22 partially overhanging relative to the first tab 14. When the second portion 22 partially overhangs relative to the first tab 14, the overhanging portion of the second portion 22 relative to the first tab 14 is prone to wrinkling or adhesion to structures other than the first tab 14 and first electrode sheet 11 within the cylindrical battery, affecting battery performance. When 1mm≤L2≤W, the possibility of adhesive failure caused by a small adhesion area between the second portion 22 and the first tab 14 can be reduced, and the adhesive stability between the adhesive tape 20 and the first tab 14 can be improved.

[0066] In some embodiments, see Figure 1 and Figure 2 The first pole piece 11 of the outermost circle includes a coated area 11b and a hollow foil area 11c. The winding tail end 11a is one end of the hollow foil area 11c, and the first pole tab 14 is connected to the hollow foil area 11c.

[0067] By arranging the first tab 14 to be connected to the empty foil area 11 c of the outermost circle of the first pole piece 11 , the welding point between the first tab 14 and the first pole piece 11 is located at the outermost circle of the first pole piece 11 , so as to facilitate the bonding of the adhesive tape 20 .

[0068] In some embodiments, see Figure 1 and Figure 2 , along the winding direction x of the electrode assembly 10 , the length L1 of the first portion 21 satisfies: L1 ≥ A / 3. Wherein, A is the length of the empty foil area 11c between the first tab 14 and the coated area 11b along the winding direction x of the electrode assembly 10 . It should be noted that Figure 1 The case of L1>A is shown. In other embodiments, see Figure 3, the length L1 of the first portion 21 of the adhesive tape 20 may also satisfy A≥ L1≥A / 3.

[0069] By setting L1 ≥ A / 3, the possibility of adhesion failure caused by a small adhesion area between the first portion 21 and the first electrode piece 11 can be reduced, which is beneficial to improving the adhesion stability between the adhesive tape 20 and the first electrode piece 11 .

[0070] In some embodiments, see Figure 1 The cylindrical battery 100 further includes a housing (not shown), in which the electrode assembly 10 is housed.

[0071] Along the winding direction x of the electrode assembly 10 , the length L of the adhesive tape 20 satisfies: L1+L2≤L≤C, where L1 is the length of the first portion 21 , L2 is the length of the second portion 22 , and C is the circumference of the inner circumference of the shell.

[0072] The motor assembly can be accommodated by providing a housing. Setting L1+L2≤L, meaning the minimum length of the adhesive tape 20 is the sum of the lengths of the first portion 21 and the second portion 22, allows the portion of the adhesive tape 20 extending beyond the first and second portions 21, 22 to be attached to the side of the second portion 22 near the winding end 11a, improving the adhesive stability of the adhesive tape 20. Setting L≤C, meaning the maximum length of the adhesive tape 20 is no greater than the inner circumference of the housing, reduces the impact on assembly. L1+L2≤L≤C not only improves the adhesive stability of the adhesive tape 20 but also prevents assembly issues caused by excessively long adhesive tape 20.

[0073] In some embodiments, the cylindrical battery further includes a housing, and the electrode assembly 10 is housed in the housing. The electrode assembly 10 is cylindrical.

[0074] The elongation δ of the adhesive tape 20 satisfies: δ≥1.2×((2πR-2πr) / 2πr), where R is the inner radius of the shell, π is pi, and r is the radius of the electrode assembly 10.

[0075] Compared with cylindrical batteries, the size of the adhesive tape 20 is smaller, and the microscale stretching equipment has the advantages of high-resolution mechanical loading, non-contact strain measurement, and non-destructive clamping. Therefore, the microscale stretching equipment can be used to test the elongation δ of the adhesive tape 20. The specific measurement method is as follows: Cut a 2 mm wide and 6 mm long strip of adhesive tape 20, fix the strip with a vacuum micro suction cup, and set the aperture of the vacuum cup to 1–3 μm and the vacuum degree to less than Pa, the adsorption force is greater than 10 mN. First, preload 0.5 mN and hold for 30 seconds to eliminate the clamping gap. Then, stretch the spline at a stretching speed of 0.1 μm / s until the spline breaks. The test is stopped. The sampling frequency is set as follows: the sampling frequency of the elastic section is not less than 100 Hz; the sampling frequency after yielding is not less than 500 Hz (to capture localized deformation). Record the gauge length at the time of fracture, according to The elongation δ of the spline is calculated, where is the original gauge length, and Lf is the gauge length at fracture.

[0076] The inner radius R of the outer shell is measured by scanning the cylindrical battery 100 with a computed tomography (CT) device and measuring the inner diameter of the outer shell, where R is half the length of the inner diameter.

[0077] By setting δ≥1.2×((2πR−2πr) / 2πr), the possibility of the adhesive tape 20 breaking can be reduced while the pulling force is distributed. In some embodiments, see Figure 2 Along the extension direction z of the winding centerline, the width h of the adhesive tape 20 satisfies: 0.2H≤h≤H. Wherein, H is the width of the first pole piece 11.

[0078] By setting 0.2H≤h, the possibility of insufficient force sharing due to the tape 20 being too narrow can be reduced; by setting h≤H, the possibility of the tape 20 being too wide affecting the assembly of the bare cell can be reduced. When 0.2H≤h≤H, the pulling force can be shared as much as possible while also reducing the possibility of the tape 20 being too wide affecting the assembly of the bare cell.

[0079] In some embodiments, the thickness t of the adhesive tape 20 satisfies: 0.01 mm ≤ t ≤ 0.1 mm. t can be one of 0.02 mm, 0.05 mm, 0.07 mm, 0.09 mm, and 0.1 mm.

[0080] By setting 0.01mm≤t, the possibility of insufficient force sharing due to the adhesive tape 20 being too thin can be reduced. By setting t≤0.1mm, the possibility of the adhesive tape 20 being too thick affecting the bare cell diameter and making assembly difficult can be reduced. When 0.01mm≤t≤0.1mm, the pulling force can be shared as much as possible while reducing the possibility of the adhesive tape 20 being too thick affecting assembly.

[0081] In some embodiments, see Figure 1 and Figure 2 The adhesive tape 20 is located on the side of the first pole piece 11 away from the winding center line.

[0082] The adhesive tape 20 is arranged on the outermost side of the first pole piece 11 to facilitate bonding. In some embodiments, the adhesive tape 20 includes a substrate layer and an adhesive layer coated on the substrate layer. The peel strength between the adhesive layer and the first electrode 11 is F, 0.5 N / mm≤F≤10 N / mm. F can be one of 0.8 mm, 1.0 mm, 4.5 mm, 7.3 mm, or 9.5 mm.

[0083] The test method for the peel strength F between the adhesive layer and the first pole piece 11 is as follows: the peel strength between the adhesive layer and the first pole piece 11 is tested using a high-speed rail tensile tester according to GB / T 2792-2014 "Test method for peel strength of adhesive tapes". The test process is as follows: Discharge the cylindrical battery 100 to a cutoff voltage (e.g., 3.0V). Then disassemble the cylindrical battery 100 and remove the first electrode piece 11 and the adhesive tape 20 attached to it as a whole. Wipe the surface of the electrolyte with dust-free paper. Then cut the adhesive tape 20 and the first electrode piece 11 into strips. Along the length of the sample, adhere the side of the first electrode piece 11 not covered with the adhesive tape 20 to a steel plate using double-sided tape (Nitto 5000NS), with the adhesive tape length being no less than 5 mm. Secure the steel plate to the corresponding position on a high-speed rail tensile testing machine. Pull up one end of the adhesive tape 20 on the other side of the sample and clamp it in a chuck. The pulled portion of the adhesive tape 20 forms a 180° angle with the steel plate. Pull the sample at a speed of 5±0.2 mm / s. The average tensile force measured in the plateau region is recorded as the peel strength between the adhesive layer of the adhesive tape 20 and the first electrode piece 11, expressed in N / mm. The stable region refers to a portion of a line graph showing no significant change in the pulling force of the adhesive tape 20 pulled by the clamp over time.

[0084] By setting 0.5 N / mm≤F≤10 N / mm, the bonding strength between the adhesive tape 20 and the first pole piece 11 is ensured. In some embodiments, the adhesive layer comprises one of acrylic resin adhesive, polyimide adhesive, or silicone-fluororubber composite adhesive, and the substrate layer comprises one of polypropylene, polyethylene terephthalate, or polyimide. By selecting different material types and / or qualities, the adhesive strength of the adhesive tape 20 can be adjusted, thereby adjusting the peel strength between the adhesive layer and the first electrode 11.

[0085] It should be noted that the peel strength between the adhesive layer and the first electrode 11 before being soaked in the electrolyte affects the peel strength F between the adhesive layer and the first electrode 11 after being soaked in the electrolyte. Therefore, by selecting different material types and / or qualities to adjust the bonding strength of the adhesive paper 20, F can be adjusted.

[0086] In some embodiments, see Figure 2The first electrode tab 14 is welded to the first electrode piece 11 to form a welding area 15 , and the second portion 22 at least partially covers the welding area 15 .

[0087] By arranging the second portion 22 to at least partially cover the welding area 15 , it is possible to reduce the pulling on the welding point and lower the risk of fracture at the welding edge. In some embodiments, see Figure 1 The adhesive tape 20 also includes a third part 23. The first part 21, the second part 22 and the third part 23 are connected in sequence. The third part 23 is attached to the first electrode sheet 11. Along the winding direction x of the electrode assembly 10, the third part 23 is located on the second side 22b.

[0088] It should be noted that Figure 1 FIG. 2 shows a case where the adhesive tape 20 includes a third portion 23. In other embodiments, see Figure 3 , the adhesive tape 20 may not be provided with the third part.

[0089] By providing the third portion 23 , the adhesive tape 20 can cover the entire welding area 15 , which can not only improve the bonding stability, but also cover the burrs generated at the welding location, thereby reducing the negative impact of the burrs on battery performance.

[0090] In some embodiments, see Figure 1 The electrode assembly 10 also includes a second electrode piece 12 and a second electrode tab (not shown). The second electrode piece 12 has an opposite polarity to the first electrode piece 11. The outermost circle of the first electrode piece 11 is located outside the outermost circle of the second electrode piece 12, and the second electrode tab is connected to the second electrode piece 12.

[0091] The electrode assembly 10 is formed by providing a second electrode piece 12 having a polarity opposite to that of the first electrode piece 11 and providing a second electrode tab connected to the second electrode piece 12 .

[0092] In some embodiments, see Figure 1 The first electrode piece 11 is a negative electrode piece, and the first electrode tab 14 is a negative electrode tab. By setting the first electrode sheet 11 as a negative electrode sheet and the first electrode tab 14 as a negative electrode tab, the adhesive tape 20 can be attached to the negative electrode sheet and the negative electrode tab. The adhesive tape 20 distributes the pulling force on the negative electrode sheet, reducing the risk of the negative electrode sheet breaking at the welding edge.

[0093] In some embodiments, reference Figure 4 , an embodiment of the present application further provides an electric device 1000, comprising the cylindrical battery 100 provided in any of the above embodiments.

[0094] In some embodiments, the cylindrical battery 100 is a secondary battery, such as a lithium-ion battery or a sodium-ion battery; in some embodiments, the cylindrical battery 100 is a button secondary battery.

[0095] The cylindrical battery 100 serves as a power source for the electrical device 1000 , and the cylindrical battery 100 provides electrical energy for the electrical device 1000 to operate.

[0096] The cylindrical battery 100 provided in any of the above embodiments has good safety performance, so that the electrical device 1000 powered by the cylindrical battery 100 has good electrical safety and reliability.

[0097] In order to verify the impact of the solution provided in the embodiment of the present application on the service life of the cylindrical battery 100, the inventors of the present application conducted the following experiments.

[0098] The experiment includes 2 groups of comparative examples and 23 groups of examples, each group of comparative examples and each group of examples includes 10 cylindrical batteries 100. In this experiment, the first electrode 11 is set as the negative electrode, and the second electrode 12 is set as the positive electrode.

[0099] In Example 1, the preparation process of the cylindrical battery cell 100 is as follows: (1) Preparation of the first electrode sheet 11, i.e., the negative electrode sheet: The negative electrode active materials, artificial graphite, silicon carbon material, conductive carbon black (Super P), polyacrylic acid binder (PAA), and lithium difluorophosphate (LDPF), are mixed in a weight ratio of 69:5:6:19:1, deionized water is added as a solvent, and a slurry with a weight percentage of 55 wt% is prepared and stirred evenly. The slurry is evenly coated on the first side of a copper foil with a thickness of 10 μm, dried at 90°C, and the above coating steps are repeated on the second side of the copper foil to obtain a double-sided coated negative electrode sheet. The initial negative electrode sheet is rolled to obtain a negative electrode active material layer. Then, a first electrode tab 14 with a thickness of 60 μm is welded to the tail of the copper foil by ultrasonic welding. The first electrode tab 14 is made of copper, and adhesive tape 20 is pasted on the first electrode tab 14 and the side of the first electrode tab 14 near the winding center.

[0100] (2) Preparation of the second electrode sheet 12, i.e., the positive electrode sheet: The positive electrode active material lithium cobalt oxide (LiCoO2), conductive carbon black (Super P), and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 96.5:1.5:2, and N-methylpyrrolidone (NMP) is added as a solvent to prepare a slurry with a solid content of 75wt%, and stirred evenly. The slurry is evenly coated on the third side of an aluminum foil with a thickness of 10μm, dried at 90°C, and the above coating steps are repeated on the fourth side of the aluminum foil to obtain a double-sided coated positive electrode sheet. The initial positive electrode sheet is cold pressed to obtain a positive electrode active material layer, and then cut and other processes are performed to obtain a positive electrode sheet. A second electrode tab with a thickness of 60μm is welded to the tail of the aluminum foil by ultrasonic welding. The second electrode tab is made of aluminum.

[0101] (3) Preparation of electrolyte: In a dry argon atmosphere, organic solvents ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed at a mass ratio of EC:EMC:DEC = 30:50:20. Then, lithium salt lithium hexafluorophosphate (LiPF6) was added to the organic solvent, dissolved and mixed evenly to obtain an electrolyte with a lithium salt concentration of 1.15 mol / L.

[0102] (4) Preparation of the isolation film 13: A polyethylene (PE) film with a thickness of 9 μm was selected.

[0103] (5) Preparation of cylindrical battery 100: The first electrode sheet 11, the separator 13, and the second electrode sheet 12 are stacked and wound in sequence to obtain an electrode assembly 10 with an outer diameter of 20 mm. The outermost ring of the electrode assembly 10 is the first electrode sheet 11. The electrode assembly 20 is placed in the shell body of the shell, and the first electrode tab 14 is welded to the electrode column along the extension direction z of the winding center line of the electrode assembly 10, and the second electrode tab is welded to the shell body. Then, the electrolyte is injected into the shell body, and the cover of the shell is welded to the shell body. After formation, a secondary battery is obtained. Among them, the outermost ring of the negative electrode sheet is connected to the first electrode tab 14, and the positive electrode sheet is connected to the second electrode tab. The adhesive tape 20 is attached between the outermost ring of the negative electrode sheet and the first electrode tab 14. Specifically, the first part 21 of the adhesive tape 20 is attached to the first electrode sheet 11, and the second part 22 of the adhesive tape 20 is attached to the first electrode tab 14. Among them, the various parameters of the adhesive tape 20 are all shown in Table 1.

[0104] The substrate layer of the adhesive tape 20 is made of PET substrate, and the dimensions of the cylindrical battery 100 are as follows: the inner radius of the shell R = 5 mm, the radius of the electrode assembly r = 4.8 mm; along the winding direction x of the electrode assembly 10, the length A = 6 mm of the empty foil area 11 c between the first electrode tab 14 and the coated area 11 b; the width H = 4 mm of the first electrode sheet 11; the width W = 3 mm of the first electrode tab 14 along the winding direction x of the electrode assembly 10; the thickness of the first electrode sheet 11 is 10 μm; the thickness of the first electrode tab 14 is 60 μm.

[0105] Examples 2 to 23 Examples 2 to 23 include most of the operating steps in Example 1. The difference from Example 1 is that some parameters in the preparation process of the cylindrical battery 100 are adjusted to vary within a certain range. See Table 1 for details.

[0106] Comparative Example 1 Comparative Example 1 includes most of the operating steps in Example 1. The difference from Example 1 is that no adhesive tape is provided in Comparative Example 1. For details, see Table 1.

[0107] Comparative Example 2 Comparative Example 2 includes most of the operating steps in Example 1. The difference from Example 1 is that the angle α between the first virtual line and the second virtual line of the adhesive tape 20 in Comparative Example 2 is less than 10°. See Table 1 for details.

[0108] After the cylindrical batteries 100 in Comparative Examples 1-2 and Examples 1-23 were prepared, a long-cycle test was performed on each group of cylindrical batteries 100. The test process was as follows: the cylindrical batteries 100 to be tested were placed on a test platform and maintained at a test temperature of 25°C. The cylindrical batteries 100, which had reached a constant temperature, were charged at a constant current of 0.2C to a voltage of the cutoff voltage. They were then charged at a constant voltage of the cutoff voltage to a current of 0.02C. They were then discharged at a constant voltage of 0.2C to a voltage of 3.0V. One charge and discharge cycle was defined as one cycle. A total of 800 cycles were performed. After the cycle test was completed, the cells were disassembled and the fracture conditions at the weld edge of the weld between the negative electrode sheet and the first tab 14 in each group of cylindrical batteries 100 were recorded. The experimental results are recorded in Table 1 below.

[0109] Table 1

[0110] Note: In the table, “ / ” means there is no such data.

[0111] As can be seen from Table 1, the number of cylindrical batteries 100 in Examples 1-23 that had cracks or fractures on the weld edge during the cycle test was lower than the number of cylindrical batteries 100 in Comparative Examples 1-2 that had cracks or fractures on the weld edge. This indicates that, in the cylindrical batteries 100 in Examples 1-23, the first portion 21 of the adhesive tape 20 was attached to the first electrode sheet 11, the second portion 22 of the adhesive tape 20 was attached to the first tab 14, and the angle α between the line connecting the end of the first portion 21 close to the second portion 22 and the winding center O (i.e., the first virtual line s1) and the line connecting the end of the first portion 21 away from the second portion 22 and the winding center O (i.e., the second virtual line s2) was ≥10°. Therefore, when the electrode assembly 10 expands in volume during charge and discharge, the adhesive tape 20 can distribute the pulling force on the first electrode sheet 11, thereby reducing the pulling at the weld and reducing the risk of the first electrode sheet 11 fracture at the weld edge.

[0112] It can be seen from Table 1 that in Examples 1-3, the number of cylindrical batteries 100 with cracks or breakage on the weld edge in Examples 1-3 where the length L2 of the second portion 22 of the adhesive tape 20 satisfies 1mm≤L2≤W is lower than that in Comparative Example 1. It can be seen that setting 1mm≤L2≤W can reduce the possibility of adhesive failure caused by the smaller adhesive area between the second portion 22 and the first tab 14, which is beneficial to improving the bonding stability between the adhesive tape 20 and the first tab 14.

[0113] It can be seen from Table 1 that in Examples 3-13, the number of cylindrical batteries 100 with cracks or breakage on the weld edge in Examples 3-13 where the angle α between the line connecting the end of the first portion 21 close to the second portion 22 and the winding center O (i.e., the first virtual line s1) and the line connecting the end of the first portion 21 away from the second portion 22 and the winding center O (i.e., the second virtual line s2) is ≥10° is lower than that in Comparative Examples 1-2. It can be seen that setting α ≥ 10° can reduce the possibility of adhesion failure caused by the smaller adhesion area between the first portion 21 and the first electrode sheet 11, and is more conducive to sharing the pulling force on the first electrode sheet 11. Among them, the number of cylindrical batteries 100 with cracks or breaks on the weld edges in Examples 3, 6-13 where the length L1 of the first part 21 of the adhesive tape 20 satisfies L1≥A / 3 is lower than that in Example 5. It can be seen that setting L1≥A / 3 on the basis of the angle α≥10° can further reduce the possibility of adhesive failure caused by the small adhesive area between the first part 21 and the first electrode 11, which is beneficial to improving the bonding stability between the adhesive tape 20 and the first electrode 11.

[0114] As shown in Table 1, in Examples 3 and 14-18, the number of cylindrical batteries 100 with cracks or fractures on the weld edge in Examples 3 and 15-17, where the width h of the adhesive tape 20 satisfies 0.2H≤h≤H, is lower than in Example 14. This indicates that setting 0.2H≤h≤H can reduce the possibility of insufficient force sharing due to the adhesive tape 20 being too narrow. While the number of cylindrical batteries 100 with cracks or fractures on the weld edge in Example 18, where the width h of the adhesive tape 20 is greater than H, is lower than in Example 14, the adhesive tape 20 is wider than the first electrode sheet 11, resulting in wasted adhesive tape 20 and a loss of energy density.

[0115] As shown in Table 1, in Examples 3 and 19-23, the number of cylindrical batteries 100 with cracks or fractures on the weld edge was lower in Examples 3 and 20-22, where the thickness t of the adhesive tape 20 satisfies 0.01 mm ≤ t ≤ 0.1 mm, than in Example 19. This indicates that setting 0.01 mm ≤ t ≤ 0.1 mm can reduce the possibility of insufficient force sharing due to the adhesive tape 20 being too thin. While the number of cylindrical batteries 100 with cracks or fractures on the weld edge was lower in Example 23, where the thickness t of the adhesive tape 20 was greater than 0.1 mm, was lower than in Example 19, the thicker adhesive tape 20 affected the diameter of the bare cell, making assembly more difficult. The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may be subject to various modifications and variations.

Claims

1. A cylindrical battery, characterized in that: include: An electrode assembly, wherein the electrode assembly is a wound structure, the electrode assembly has a winding centerline, the electrode assembly includes a first pole piece and a first pole tab, the outermost circle of the first pole piece is connected to the first pole tab, and the first pole piece has a winding tail end; Adhesive tape, the adhesive tape comprising a first portion and a second portion connected to each other, the first portion being attached to the first electrode sheet, and the second portion being attached to the first electrode tab; the second portion comprising a first side and a second side oppositely disposed along the winding direction of the electrode assembly, the second side being closer to the winding end than the first side, and the first portion being located on the first side; Observed from the extension direction of the winding centerline, a line connecting one end of the first part close to the second part and the winding center is defined as a first virtual line, and a line connecting one end of the first part away from the second part and the winding center is defined as a second virtual line, and an angle between the first virtual line and the second virtual line is α, α≥10°.

2. The cylindrical battery according to claim 1, characterized in that: Along the winding direction of the electrode assembly, the length L2 of the second portion satisfies: 1 mm ≤ L2 ≤ W; wherein W is the width of the first electrode tab along the winding direction of the electrode assembly.

3. The cylindrical battery according to claim 1, characterized in that: The first pole piece of the outermost circle includes a coating area and a hollow foil area, the winding tail end is one end of the hollow foil area, and the first pole tab is connected to the hollow foil area.

4. The cylindrical battery according to claim 3, characterized in that: Along the winding direction of the electrode assembly, the length of the empty foil area between the first electrode tab and the coating area is A, the length of the first portion is L1, and L1 ≥ A / 3.

5. The cylindrical battery according to claim 1, characterized in that: The cylindrical battery further includes a housing, wherein the electrode assembly is housed in the housing; Along the winding direction of the electrode assembly, the length of the first portion is L1, the length of the second portion is L2, the circumference of the inner circumference of the shell is C, the length of the adhesive tape is L, and L1+L2≤L≤C.

6. The cylindrical battery according to claim 1, characterized in that The cylindrical battery further includes a housing, wherein the electrode assembly is housed in the housing; The elongation δ of the adhesive tape satisfies: δ≥1.2×((2πR-2πr) / 2πr), wherein R is the inner radius of the shell, π is pi, and r is the radius of the electrode assembly.

7. The cylindrical battery according to claim 1, characterized in that: Along the extension direction of the winding center line, the width of the first pole piece is H, the width of the adhesive tape is h, and 0.2H≤h≤H.

8. The cylindrical battery according to claim 1, characterized in that: The thickness t of the adhesive tape satisfies: 0.01 mm ≤ t ≤ 0.1 mm.

9. The cylindrical battery according to claim 1, characterized in that: The adhesive tape is located on a side of the first pole piece away from the winding center line.

10. The cylindrical battery according to claim 1, characterized in that: The adhesive tape includes a base material layer and an adhesive layer. The peeling strength between the adhesive layer and the first electrode is F, and 0.5N / mm≤F≤10N / mm.

11. The cylindrical battery according to claim 10, characterized in that: The adhesive layer includes acrylic resin adhesive, polyimide adhesive or organic silicon-fluororubber composite adhesive.

12. The cylindrical battery according to claim 10, characterized in that: The material of the substrate layer is polypropylene, polyethylene terephthalate or polyimide.

13. The cylindrical battery according to claim 1, characterized in that: The first electrode tab and the first electrode piece are welded to form a welding area, and the second portion at least partially covers the welding area.

14. The cylindrical battery according to claim 1, characterized in that: The adhesive tape also includes a third part. The first part, the second part and the third part are connected in sequence. The third part is attached to the first electrode sheet and is located on the second side along the winding direction of the electrode assembly.

15. The cylindrical battery according to claim 1, characterized in that: The electrode assembly further includes a second pole piece and a second pole tab. The second pole piece has opposite polarity to the first pole piece. The outermost circle of the first pole piece is located outside the outermost circle of the second pole piece. The second pole tab is connected to the second pole piece.

16. The cylindrical battery according to claim 1, characterized in that: The first electrode is a negative electrode.

17. An electrical device, characterized in that: The invention comprises a cylindrical battery according to any one of claims 1 to 16.

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