Cylindrical batteries and electronic devices

Abstract

Embodiments of the present application provide cylindrical batteries and electronic devices. The cylindrical battery includes a wound electrode assembly, the electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive current collector, a positive active material layer, and an insulating layer, the positive active material layer and the insulating layer are both arranged on at least one side of the positive current collector, the positive current collector includes a first region corresponding to the positive active material layer, a second region corresponding to the insulating layer, and a third region not covered by the positive active material layer or the insulating layer, wherein in the width direction of the positive current collector, the second region is located between the first region and the third region; the insulating layer includes a first portion having a first width W1 and a second portion having a second width W2, W1+2mm≤W2≤W1+10mm, and the second portion is located outside the electrode assembly. The insulating layer of the present application can cover the R corner of the electrode assembly to prevent the electrode assembly from contacting the shell.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical energy storage, and in particular to cylindrical batteries and electronic devices. Background Art

[0002] With the development of electrochemical energy storage technology, higher and higher requirements are placed on the safety performance and energy density of cylindrical batteries (e.g., lithium-ion batteries), and further improvements in this regard are expected. Summary of the Invention

[0003] The present application provides a cylindrical battery, which includes a wound electrode assembly, the electrode assembly includes a positive electrode sheet, the positive electrode sheet includes a positive electrode collector, a positive electrode active material layer and an insulating layer, the positive electrode active material layer and the insulating layer are both arranged on at least one side of the positive electrode collector, the positive electrode collector includes a first region corresponding to the positive electrode active material layer, a second region corresponding to the insulating layer, and a third region not covered by the positive electrode active material layer or the insulating layer, wherein in the width direction of the positive electrode collector, the second region is located between the first region and the third region; the insulating layer includes a first portion having a first width W1 and a second portion having a second width W2, W1+2mm≤W2≤W1+10mm, and the second portion is located outside the electrode assembly.

[0004] In some embodiments, the insulating layer further includes a transition portion between the first and second portions, and the angle α of the transition interface of the transition portion is between 10° and 90°. In some embodiments, the insulating layer and the positive electrode active material layer at least partially overlap in the thickness direction of the positive electrode current collector, and the width W of the overlapping region satisfies the following relationship: 0.5 ≤ W ≤ 3 mm. In some embodiments, the length L2 of the second portion, in conjunction with the electrode assembly diameter d, the first width W1, the second width W2, the thickness h of the positive electrode tab, and the angle α, satisfies the following relationship: πd + (W2 - W1) × cotα ≤ L2 ≤ 2π(dh) + (W2 - W1) × cotα. In some embodiments, the first width W1 is between 1 mm and 5 mm, and the second width W2 is between 3 mm and 15 mm. In some embodiments, the thickness H1 of the insulating layer is between 10 μm and 100 μm. In some embodiments, the thickness H1 of the insulating layer and the thickness H2 of the positive electrode active material layer satisfy the following relationship: 0.1H2 ≤ H1 ≤ 0.5H2. In some embodiments, the flexural stress of the insulating layer is less than or equal to 0.04 N. In some embodiments, the bonding force between the insulating layer and the positive electrode current collector is greater than or equal to 20 N / m.

[0005] An embodiment of the present application further provides an electronic device comprising the above-mentioned cylindrical battery.

[0006] The insulating layer of the present application includes a first portion having a first width W1 and a second portion having a second width W2, W1+2mm≤W2≤W1+10mm, and the second portion is located on the outside of the electrode assembly. In this way, while preventing contact short circuit between the positive electrode sheet and the negative electrode sheet, it can cover the R corner of the electrode assembly to prevent the electrode assembly from contacting the shell. In addition, a gluing process can be eliminated, thereby reducing manufacturing costs while ensuring the safety of the electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 A top view of a positive electrode tab in an unfolded state according to some embodiments is shown.

[0008] Figure 2 A cross-sectional view of a positive electrode sheet according to some embodiments is shown, taken along a plane including a width direction and a thickness direction.

[0009] Figure 3 A schematic diagram of a conventional wound electrode assembly is shown.

[0010] Figure 4 A schematic diagram of a wound electrode assembly according to some embodiments is shown. DETAILED DESCRIPTION

[0011] The following embodiments may enable those skilled in the art to more fully understand the present application, but do not limit the present application in any way.

[0012] The present application provides a cylindrical battery, which includes a wound electrode assembly. In some embodiments, the electrode assembly includes a positive electrode sheet 10. Figure 1 The diagram shows a plan view of the positive electrode tab 10 in an unfolded state. Figure 2 1 shows a cross-sectional view of the positive electrode sheet 10 taken along the planes in the width direction and the thickness direction. Figure 1 As shown, the positive electrode sheet 10 includes a positive electrode current collector 101, an insulating layer 102 and a positive electrode active material layer 103. The positive electrode active material layer 103 and the insulating layer 102 are both arranged on at least one side of the positive electrode current collector 101. It should be understood that although Figure 2 In the figure, the insulating layer 102 and the positive active material layer 103 are shown as being located on both sides of the positive current collector 101 , but this is merely exemplary, and the insulating layer 102 and the positive active material layer 103 may only be present on one side of the positive current collector 101 .

[0013] In some embodiments, as Figure 1As shown, the positive electrode current collector 101 includes a first region 1011 corresponding to the positive electrode active material layer 103, a second region 1012 corresponding to the insulating layer 102, and a third region 1013 not covered by the positive electrode active material layer 103 or the insulating layer 102. In some embodiments, in the width direction ( Figure 1 In the up-down direction shown in ), the second area 1012 is located between the first area 1011 and the third area 1013.

[0014] In some embodiments, the insulating layer 102 includes a first portion 1021 having a first width W1 and a second portion 1022 having a second width W2, W1+2mm≤W2≤W1+10mm, the second portion 1022 is located on the outside of the electrode assembly, and the first portion 1021 of the insulating layer 102 is located on the inside or interior of the electrode assembly.

[0015] Figure 3 A schematic diagram of an existing wound electrode assembly is shown. Generally, after the electrode assembly is prepared, the electrode assembly is encapsulated in a shell (e.g., a metal shell). In order to prevent the electrode assembly from contacting the shell, glue needs to be applied at least at the R corner of the electrode assembly. Figure 4 A schematic diagram of an electrode assembly according to some embodiments of the present application is shown. In the present application, the insulating layer 102 includes a first portion 1021 having a first width W1 and a second portion 1022 having a second width W2, W1+2mm≤W2≤W1+10mm, and the second portion 1022 is located on the outside of the electrode assembly. On the one hand, only by satisfying W1+2mm≤W2 can the R corner of the electrode assembly be effectively covered; on the other hand, only by satisfying W2≤W1+10mm can sufficient space be reserved for welding the current collecting plate, otherwise it is easy to cause poor welding. In this way, the insulating layer 102 can cover the R corner of the electrode assembly while preventing contact short circuit between the positive electrode sheet and the negative electrode sheet, preventing the electrode assembly from contacting the packaging shell. In addition, the above-mentioned existing glue laminating process can be eliminated, thereby reducing manufacturing costs while ensuring the safety of the electrode assembly.

[0016] In some embodiments, as Figure 1 As shown, the insulating layer 102 further includes a transition portion 1023 located between the first portion 1021 and the second portion 1022. The angle α of the transition interface of the transition portion 1023 is 10° to 90°. The angle α of the transition interface of the transition portion 1023 refers to the angle of the outer boundary of the transition portion 1023 relative to the extension direction of the insulating layer 102 ( Figure 1 By setting the angle α to 10° to 90°, the coating process of the insulating layer 102 is simplified.

[0017] In some embodiments, the insulating layer 102 and the positive electrode active material layer 103 at least partially overlap in the thickness direction of the positive electrode current collector 101. For example, the positive electrode active material layer 103 may cover a portion of the insulating layer 102, or the insulating layer 102 may cover a portion of the positive electrode active material layer 103, or a portion of the positive electrode active material layer 103 and a portion of the insulating layer 102 may interpenetrate each other. In some embodiments, the width of the overlapping region satisfies 0.5 mm ≤ W ≤ 3 mm. The presence of the overlapping region can further improve the interfacial stability between the second portion 1022 and the positive electrode active material layer 103, further improving the safety performance of the electrode assembly.

[0018] In some embodiments, the length L2 of the second portion 1022 satisfies the following relationship with the electrode assembly's diameter d, the first width W1, the second width W2, the thickness h of the positive electrode tab 10, and the angle α: πd + (W2 - W1) × cotα ≤ L2 ≤ 2π(dh) + (W2 - W1) × cotα. On the one hand, when L2 ≥ πd + (W2 - W1) × cotα, the last circle of the insulation layer 102 can fully wrap around the R corner of the electrode assembly. On the other hand, when L2 ≤ 2π(dh) + (W2 - W1) × cotα, at most the last two circles of the insulation layer 102 can wrap around the R corner, thus not affecting the subsequent welding area of ​​the current collecting plate.

[0019] In some embodiments, the first width W1 is 1 mm to 5 mm. When the first width W1 is less than 1 mm, it is difficult to achieve the desired result. When the first width W1 is greater than 5 mm, the volumetric energy density of the cylindrical battery is affected. In some embodiments, the second width W2 is 3 mm to 15 mm. When the second width W2 is less than 3 mm, it is difficult to cover the rounded corners of the electrode assembly. When the second width W2 is greater than 15 mm, it will affect the welding area of ​​the current collector, resulting in an unstable weld.

[0020] In some embodiments, as Figure 2 As shown, the thickness H1 of the insulating layer 102 is 10 μm to 100 μm. When the thickness H1 is less than 10 μm, there is a risk of poor insulation effect. When the thickness H1 is greater than 100 μm, the bonding strength and flexibility of the insulating layer 102 will deteriorate. When the tab is flattened, the insulating layer 102 is likely to fall off, resulting in large self-discharge of the electrode assembly. In some embodiments, the thickness H1 of the insulating layer 102 and the thickness H2 of the positive electrode active material layer 103 satisfy the following relationship: 0.1H2≤H1≤0.5H2. If the thickness H1 of the insulating layer 102 is too large, the cold pressing cannot meet the requirements due to the limitations of the material used for the insulating layer 102; if the thickness H1 of the insulating layer 102 is too small, the insulation effect is poor.

[0021] In some embodiments, the flexural stress of the insulating layer 102 is less than or equal to 0.04 N. If the flexural stress of the insulating layer 102 is greater than 0.04 N, the electrode sheet may easily fall off due to insufficient flexibility when the tab is flattened, resulting in increased self-discharge of the electrode assembly. In some embodiments, the bonding force between the insulating layer 102 and the positive electrode current collector 101 is greater than or equal to 20 N / m. If the bonding force between the insulating layer 102 and the positive electrode current collector 101 is less than 20 N / m, the insulating layer 102 may fall off due to insufficient bonding force when the tab is flattened, resulting in increased self-discharge of the electrode assembly.

[0022] In some embodiments, the positive electrode current collector 101 may be made of aluminum foil. Of course, other common positive electrode current collectors in the art may also be used. In some embodiments, the thickness of the positive electrode current collector may be 1 μm to 50 μm.

[0023] In some embodiments, the positive electrode active material layer 103 may include a positive electrode active material, a conductive agent, and a binder. In some embodiments, the positive electrode active material may include at least one of lithium cobalt oxide, lithium iron phosphate, lithium aluminate, lithium manganate, or lithium nickel cobalt manganate. In some embodiments, the conductive agent of the positive electrode plate 10 may include at least one of conductive carbon black, lamellar graphite, graphene, or carbon nanotubes. In some embodiments, the binder in the positive electrode plate 10 may include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, a polyamide, polyacrylonitrile, a polyacrylate, a polyacrylic acid, a polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. In some embodiments, the mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode active material layer 103 is (80-99):(0.1-10):(0.1-10), but this is merely an example, and any other suitable mass ratio may be used.

[0024] In some embodiments, insulating layer 102 may include a binder and inorganic particles. In some embodiments, the binder in insulating layer 102 may include at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, a styrene-acrylate copolymer, a styrene-butadiene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, a polyacrylate, sodium carboxymethyl cellulose, polyvinyl acetate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, or polyhexafluoropropylene. In some embodiments, the inorganic particles may include ceramic particles, etc. The mass ratio of the binder to the inorganic particles in insulating layer 102 may be (20-40):(60-80), but this is merely exemplary, and other suitable mass ratios may also be used.

[0025] In some embodiments, the wound electrode assembly may further include a negative electrode sheet and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet to provide insulation. In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, wherein the negative electrode active material layer is located on one or both sides of the negative electrode current collector. In some embodiments, the negative electrode current collector may be at least one of copper foil, nickel foil, or a carbon-based current collector. In some embodiments, the negative electrode active material layer may include a negative electrode active material, a conductive agent, and a binder. In some embodiments, the negative electrode active material may include at least one of graphite and a silicon-based material. In some embodiments, the silicon-based material includes at least one of silicon, a silicon-oxygen material, a silicon-carbon material, or a silicon-oxygen-carbon material. In some embodiments, the conductive agent in the negative electrode active material layer may include at least one of conductive carbon black, Ketjen black, flake graphite, graphene, carbon nanotubes, or carbon fibers. In some embodiments, the binder in the negative electrode active material layer may include at least one of carboxymethyl cellulose (CMC), polyacrylic acid, polyvinyl pyrrolidone, polyaniline, polyimide, polyamide-imide, polysiloxane, styrene-butadiene rubber, epoxy resin, polyester resin, polyurethane resin, or polyfluorene. In some embodiments, the mass ratio of the negative electrode active material, conductive agent, and binder in the negative electrode active material layer may be (78 to 98.5): (0.1 to 10): (0.1 to 10). It should be understood that the above description is merely exemplary, and any other suitable materials and mass ratios may be employed.

[0026] In some embodiments, the separator includes at least one of polyethylene, polypropylene, polyvinylidene fluoride, polyethylene terephthalate, polyimide, or aramid. For example, the polyethylene includes at least one selected from high-density polyethylene, low-density polyethylene, or ultra-high molecular weight polyethylene. Polyethylene and polypropylene are particularly effective in preventing short circuits and can improve battery stability through the shutdown effect. In some embodiments, the separator has a thickness ranging from approximately 3 μm to 20 μm.

[0027] In some embodiments, the surface of the isolation membrane may further include a porous layer disposed on at least one surface of the isolation membrane. The porous layer includes inorganic particles and a binder. The inorganic particles are selected from at least one of aluminum oxide (Al2O3), silicon oxide (SiO2), magnesium oxide (MgO), titanium oxide (TiO2), hafnium dioxide (HfO2), tin oxide (SnO2), cerium dioxide (CeO2), nickel oxide (NiO), zinc oxide (ZnO), calcium oxide (CaO), zirconium oxide (ZrO2), yttrium oxide (Y2O3), silicon carbide (SiC), boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, or barium sulfate. In some embodiments, the pores of the isolation membrane have a diameter ranging from approximately 0.01 μm to 1 μm. The binder of the porous layer is selected from at least one of polyvinylidene fluoride, a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, sodium carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, and polyhexafluoropropylene. The porous layer on the surface of the separator can improve the separator's heat resistance, oxidation resistance, and electrolyte wettability, and enhance the adhesion between the separator and the electrode.

[0028] In some embodiments, the cylindrical battery includes a lithium-ion battery, but the present application is not limited thereto. In some embodiments, the cylindrical battery further includes an electrolyte, and the electrolyte includes at least one of a fluoroether, a fluoroethylene carbonate, or an ether nitrile. In some embodiments, the electrolyte further includes a lithium salt, and the lithium salt includes lithium bis(fluorosulfonyl)imide and lithium hexafluorophosphate, and the concentration of the lithium salt is 1 mol / L to 2 mol / L, and the mass ratio of lithium bis(fluorosulfonyl)imide to lithium hexafluorophosphate is 0.06 to 5. In some embodiments, the electrolyte may further include a non-aqueous solvent. The non-aqueous solvent may be a carbonate compound, a carboxylate compound, an ether compound, other organic solvents, or a combination thereof.

[0029] The carbonate compound may be a linear carbonate compound, a cyclic carbonate compound, a fluorinated carbonate compound, or a combination thereof.

[0030] Examples of chain carbonate compounds include diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC), methylethyl carbonate (MEC), and combinations thereof. Examples of cyclic carbonate compounds include ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylethylene carbonate (VEC), and combinations thereof. Examples of fluorocarbonate compounds include fluoroethylene carbonate (FEC), 1,2-difluoroethylene carbonate, 1,1-difluoroethylene carbonate, 1,1,2-trifluoroethylene carbonate, 1,1,2,2-tetrafluoroethylene carbonate, 1-fluoro-2-methylethylene carbonate, 1-fluoro-1-methylethylene carbonate, 1,2-difluoro-1-methylethylene carbonate, 1,1,2-trifluoro-2-methylethylene carbonate, trifluoromethylethylene carbonate, and combinations thereof.

[0031] Examples of the carboxylic acid ester compound are methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, γ-butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, methyl formate, or a combination thereof.

[0032] Examples of the ether compound are dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, ethoxymethoxyethane, 2-methyltetrahydrofuran, tetrahydrofuran, or a combination thereof.

[0033] Examples of other organic solvents are dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methylsulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, formamide, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate, trioctyl phosphate, and phosphoric acid esters or combinations thereof.

[0034] The embodiments of the present application also provide an electronic device including the above-mentioned cylindrical battery. The electronic device of the embodiment of the present application is not particularly limited, and it can be any electronic device known in the prior art. In some embodiments, the electronic device may include, but is not limited to, a laptop computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax machine, a portable copier, a portable printer, a head-mounted stereo headset, a video recorder, an LCD TV, a portable cleaner, a portable CD player, a mini disc, a transceiver, an electronic notepad, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a car, a motorcycle, a power-assisted bicycle, a bicycle, a drone, a lighting fixture, a toy, a game console, a clock, a power tool, a flashlight, a camera, a large household battery and a lithium ion capacitor, etc.

[0035] Some specific embodiments and comparative examples are listed below to better illustrate the present application, wherein a lithium-ion battery is used as an example.

[0036] Comparative Example 1

[0037] Preparation of the negative electrode sheet: Copper foil was used as the current collector, artificial graphite as the negative electrode active material, and styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as the binder. The negative electrode active material, SBR, and sodium CMC were mixed in a mass ratio of 98:1:1 and dispersed in deionized water to form a slurry. After stirring evenly, the slurry was applied to copper foil and dried to form a 120μm thick negative electrode active material layer. The negative electrode sheet was then cold-pressed and slit.

[0038] Positive electrode sheet preparation: The positive electrode active material, lithium cobalt oxide, conductive carbon black, and binder polyvinylidene fluoride (PVDF), were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 94.8:2.8:2.4. The mixture was then coated onto aluminum foil to form an 80μm thick positive electrode active material layer. The binder, polyvinylidene fluoride and Al₂O₃, were thoroughly mixed in an N-methylpyrrolidone solvent system at a mass ratio of 40:60. The mixture was then coated onto the aluminum foil on both sides of the width of the positive electrode active material layer to form an insulating layer with a thickness of 30μm. The mixture was then dried and cold-pressed to produce the positive electrode sheet.

[0039] Preparation of isolation film: Stir polyacrylate to form a uniform slurry, apply the slurry to both sides of the porous substrate (polyethylene), and form an isolation film after drying.

[0040] Preparation of the electrolyte: In an environment with a water content of less than 10 ppm, lithium hexafluorophosphate and a non-aqueous organic solvent (ethylene carbonate (EC): diethyl carbonate (DEC): propylene carbonate (PC): propyl propionate (PP): vinylene carbonate (VC) = 20:30:20:28:2, mass percentage ratio) are prepared at a mass percentage ratio of 8:92 to form an electrolyte with a lithium salt concentration of 1 mol / L.

[0041] Preparation of a lithium-ion battery: The positive electrode sheet, separator, and negative electrode sheet are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide insulation. The electrodes are then wound to form an electrode assembly. The electrode assembly is then placed in an aluminum-plastic film package. After dehydration at 80°C, the electrolyte is injected and the battery is packaged. After formation, degassing, and shaping, an 18650 lithium-ion battery with an 18mm diameter is obtained.

[0042] Comparative Example 2 and Examples 1 to 11 are based on Comparative Example 1 with some parameter changes, and the specific differences are shown in Table 1 below.

[0043] In addition, in this application, the following method is used to measure the corresponding parameters.

[0044] Flexural stress (flexibility) test of insulation layer:

[0045] The positive electrode sheet containing the insulating layer was cut into rectangular samples with a length × width = 80 mm × 20 mm using a cutting knife. The flexural stress of the samples was then tested using an Instron 3365 universal tensile testing machine using a three-point bending method.

[0046] Insulation layer adhesion test:

[0047] Use 500-grit sandpaper to smooth the surface of a stainless steel plate measuring 200mm long by 50mm wide, then clean it with alcohol and dry it. Use a knife to cut the 20mm wide double-sided tape into 60mm long rectangles and attach the cut double-sided tape to the stainless steel plate. Then use a cutting knife to cut the positive electrode sheet containing the insulating layer into a rectangular block measuring 80mm long by 20mm wide. Then, align one end of the positive electrode sheet containing the insulating layer and attach it to the double-sided tape, leaving 20cm for the positive electrode sheet. Then, use crepe tape to attach the 80mm long by 20mm wide A4 paper sheet and the reserved electrode sheet together to make a tensile sample. An Instron 3365 universal tensile testing machine was used to measure the electrode adhesion of the samples using the 90° / 180° tensile test method. The specific method was based on the "GJB 446-88 Adhesive 90° Peel Strength Test Method (Metal to Metal)" and "GB T 2790-1995 Adhesive 180° Peel Strength Test Method". Five samples were tested in each group and the average value was taken as the final adhesion value.

[0048] Table 1 shows various parameters and evaluation results of Examples 1 to 11 and Comparative Examples 1 to 2.

[0049]

[0050] By comparing Example 1 and Comparative Example 1, it can be seen that when W1+2mm≤W2, the R corner of the lithium-ion battery can be effectively covered. The same conclusion can be drawn by comparing Example 3 and Comparative Example 2.

[0051] It can be seen from Example 9 that when the thickness H1 of the insulating layer is greater than half of the thickness H2 of the positive electrode active material layer, the cold pressing process of the electrode sheet is affected.

[0052] It can be seen from Example 11 that when the thickness H1 of the insulating layer is too large, the flexural stress of the insulating layer is too large, and the bonding force between the insulating layer and the positive electrode current collector is too small, powdering is likely to occur when the insulating layer is flattened.

[0053] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of disclosure in this application is not limited to technical solutions formed by a specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents. For example, a technical solution formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application.

Claims

1. A cylindrical battery, characterized in that: include: A wound electrode assembly, the electrode assembly comprising a positive electrode sheet, the positive electrode sheet comprising a positive electrode current collector, a positive electrode active material layer, and an insulating layer, the positive electrode active material layer and the insulating layer being disposed on at least one side of the positive electrode current collector, the positive electrode current collector comprising a first region corresponding to the positive electrode active material layer, a second region corresponding to the insulating layer, and a third region not covered by either the positive electrode active material layer or the insulating layer, wherein the second region is located between the first region and the third region in a width direction of the positive electrode current collector; In the winding direction of the electrode assembly, the insulating layer includes a first portion having a first width W1 and a second portion having a second width W2, W1+2mm≤W2≤W1+10mm, and the second portion is located outside the electrode assembly; The insulating layer further includes a transition portion located between the first portion and the second portion, wherein an angle α of a transition interface of the transition portion is 10° to 90°; The length L2 of the second portion, the diameter d of the electrode assembly, the first width W1, the second width W2, the thickness h of the positive electrode sheet, and the angle α satisfy the following relationship: πd+(W2-W1)×cotα≤L2≤2π(dh)+(W2-W1)×cotα; The first width W1 is 1 mm to 5 mm, and the second width W2 is 3 mm to 15 mm.

2. The cylindrical battery according to claim 1, characterized in that: The insulating layer and the positive electrode active material layer at least partially overlap in the thickness direction of the positive electrode current collector, and a width W of the overlapping region satisfies: 0.5 mm ≤ W ≤ 3 mm.

3. The cylindrical battery according to claim 1, characterized in that: The thickness H1 of the insulating layer is 10 μm to 100 μm.

4. The cylindrical battery according to claim 1, characterized in that The thickness H1 of the insulating layer and the thickness H2 of the positive electrode active material layer satisfy: 0.1H2≤H1≤0.5H2.

5. The cylindrical battery according to claim 1, characterized in that: The flexural stress of the insulating layer is less than or equal to 0.04N.

6. The cylindrical battery according to claim 1, characterized in that The bonding force between the insulating layer and the positive electrode current collector is greater than or equal to 20 N / m.

7. An electronic device, characterized in that: The invention comprises a cylindrical battery according to any one of claims 1 to 6.

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