WO2025209249A1 - 一种二次电池和电子装置 - Google Patents

一种二次电池和电子装置

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Publication number
WO2025209249A1
WO2025209249A1 PCT/CN2025/084689 CN2025084689W WO2025209249A1 WO 2025209249 A1 WO2025209249 A1 WO 2025209249A1 CN 2025084689 W CN2025084689 W CN 2025084689W WO 2025209249 A1 WO2025209249 A1 WO 2025209249A1
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WO
WIPO (PCT)
Prior art keywords
positive electrode
secondary battery
current collector
electrode sheet
present application
Prior art date
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Pending
Application number
PCT/CN2025/084689
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English (en)
French (fr)
Inventor
朱修养
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Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Publication date
Application filed by Ningde Amperex Technology Ltd filed Critical Ningde Amperex Technology Ltd
Publication of WO2025209249A1 publication Critical patent/WO2025209249A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes

Definitions

  • the present application relates to the field of electrochemical technology, and in particular to a secondary battery and an electronic device.
  • Secondary batteries such as lithium-ion batteries
  • High-energy-density lithium-ion batteries inevitably require higher electrode density.
  • the positive electrode density is slightly improved. This is mainly because after the compaction density reaches a certain level, the positive electrode is brittle and the unit fracture strength drops sharply, affecting the safety performance of the secondary battery.
  • it is usually difficult to achieve both high density and brittle fracture resistance of the positive electrode and it is also difficult to take into account the energy density and safety performance of the secondary battery.
  • the first aspect of the present application provides a secondary battery, which includes an electrode assembly of a wound structure, the electrode assembly including a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet including a positive electrode current collector and a positive electrode material layer; the positive electrode sheet includes a corner area of the first circle starting from the winding center, the corner area is provided with a plurality of striped protrusions located between the current collector and the positive electrode material layer, and the plurality of striped protrusions are arranged at intervals; the angle ⁇ between a single striped protrusion and the length direction of the positive electrode sheet is 20° to 70°. In some embodiments of the present application, 40° ⁇ 50°.
  • the total area of the orthographic projections of the plurality of striped protrusions on the surface of the positive electrode current collector is S1
  • the area of the positive electrode current collector in the corner region is S2, and 0.057 ⁇ S1/S2 ⁇ 0.500.
  • S1/S2 the distribution density of the striped protrusions on the positive electrode current collector is appropriate, which can enhance the strength of the positive electrode sheet and improve the compaction window of the positive electrode sheet.
  • the height of a single stripe protrusion is h1
  • the thickness of the positive electrode material layer is h2, and 0.01 ⁇ h1/h2 ⁇ 0.21.
  • the force on both sides of the positive electrode current collector can be made more uniform, and the strength improvement can be more ideal. Combining the strength advantages of both sides, a better compression window improvement effect can be achieved. This further reduces the brittle fracture of the high-pressure-density positive electrode pole piece, while taking into account the energy density and safety performance of the secondary battery.
  • the striped convex portion includes an organic material and a conductive material
  • the organic material includes at least one of polyacrylonitrile, polyethylene glycol, styrene-butadiene rubber, nylon, water-based polyamide resin, dimethyl silicone rubber, polyacrylic acid, polymethyl methacrylate or polyvinylidene fluoride
  • the conductive material includes at least one of graphite and conductive fiber
  • the mass ratio of the organic material to the conductive material is (4 to 49): 1.
  • the striped convex portion includes an organic material and a conductive material and regulates the mass ratio X within the above range.
  • the thickness h3 of the positive electrode current collector is 8 ⁇ m to 10 ⁇ m.
  • the positive electrode current collector thickness is appropriate, the resulting secondary battery has a high energy density, and the production process has a high efficiency, which is conducive to industrialization.
  • the positive electrode material layer has a compaction density PD greater than or equal to 4.24 g/cm 3 .
  • a compaction density PD of the positive electrode material layer within the above range indicates high compaction of the positive electrode material layer, thereby facilitating a secondary battery with high energy density.
  • the secondary battery satisfies at least one of the following characteristics:
  • the coating area density of the positive electrode material layer is 240 mg/1540.25 mm 2 to 400 mg/1540.25 mm 2 ;
  • the unit fracture strength of the positive electrode plate is 150 MPa to 270 MPa;
  • the thickness h2 of the positive electrode material layer is 36 ⁇ m to 61 ⁇ m.
  • a secondary battery satisfying at least one of the above characteristics can achieve both energy density and safety performance.
  • the present application provides a secondary battery and an electronic device, wherein the secondary battery includes an electrode assembly of a wound structure, the electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet includes a positive current collector and a positive electrode material layer; the positive electrode sheet includes a corner area of the first corner starting from the winding center, the corner area is provided with a plurality of striped protrusions located between the current collector and the positive electrode material layer, and the plurality of striped protrusions are arranged at intervals; the angle ⁇ between a single striped protrusion and the length direction of the positive electrode sheet is 20° to 70°. In some embodiments of the present application, 40° ⁇ 50°.
  • the strength and compaction window of the positive electrode sheet can be improved, and the brittle fracture of the high-pressure compaction positive electrode sheet can be reduced, thereby taking into account both the energy density and safety performance of the secondary battery.
  • FIG2 is a schematic diagram of a partial structure of a positive electrode sheet in some embodiments of the present application.
  • lithium-ion batteries are used as an example of secondary batteries to explain the present application, but the secondary batteries of the present application are not limited to lithium-ion batteries.
  • the present application provides a secondary battery and an electronic device to reduce the brittle fracture of the high-voltage dense positive electrode plate, while taking into account the energy density and safety performance of the secondary battery.
  • the first aspect of the present application provides a secondary battery comprising a wound electrode assembly, as shown in Figures 1 and 2.
  • the electrode assembly includes a positive electrode sheet 10, a negative electrode sheet 20, and a separator 30.
  • the positive electrode sheet 10 includes a positive current collector 11 and a positive electrode material layer 12, with the positive electrode material layer 12 disposed on both surfaces of the positive electrode collector 11.
  • the positive electrode sheet 10 includes a corner region 13 at the corner of the first turn from the winding center.
  • the corner region 13 is provided with a plurality of striped protrusions 14 located between the positive current collector 11 and the positive electrode material layer 12, with the plurality of striped protrusions 14 spaced apart.
  • the positive electrode sheet 10 is wound from the winding center, i.e., the first turn, i.e., the region between line segment A-A'.
  • the corner region 13 of the first turn is also the region between line segment B-B'.
  • the angle ⁇ formed between a single striped protrusion 14 and the length direction of the positive electrode sheet is 20° to 70°. In some embodiments of the present application, 40° ⁇ 50°.
  • the angle ⁇ can be 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, or a range consisting of any two values therebetween.
  • the striped protrusion layer cannot share the bending deformation force of the positive electrode current collector, resulting in the positive electrode sheet bending and breaking, so that the compaction density window cannot be improved. Therefore, by setting the stripe protrusions and the angle ⁇ within the above range, the strength and compaction window of the positive electrode sheet can be improved, and the brittle fracture of the high-pressure compaction positive electrode sheet can be reduced, thereby taking into account both the energy density and safety performance of the secondary battery.
  • the area where the positive electrode sheet has a fold is recorded as the corner area, specifically the area where the fold extends 2 mm to both sides.
  • multiple stripe protrusions refer to stripes distributed in parallel; the length direction of the positive electrode sheet refers to the direction of the longer side of the positive electrode sheet; and a high-pressure dense positive electrode sheet refers to a positive electrode sheet with a compaction density of the positive electrode material layer greater than 4.24g/ cm3 .
  • the spacing d between two adjacent stripe convex portions is 50 ⁇ m to 500 ⁇ m
  • the width L of a single stripe convex portion is 10 ⁇ m to 300 ⁇ m
  • the height h1 is 0.5 ⁇ m to 10 ⁇ m.
  • d can be 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 120 ⁇ m, 140 ⁇ m, 150 ⁇ m, 170 ⁇ m, 190 ⁇ m, 200 ⁇ m, 250 ⁇ m, 300 ⁇ m, 350 ⁇ m, 400 ⁇ m, 450 ⁇ m, or a range consisting of any two values therebetween.
  • L may be 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m, 60 ⁇ m, 70 ⁇ m, 80 ⁇ m, 90 ⁇ m, 100 ⁇ m, 125 ⁇ m, 150 ⁇ m, 175 ⁇ m, 200 ⁇ m, 225 ⁇ m, 250 ⁇ m, 275 ⁇ m, 300 ⁇ m, or a range consisting of any two values therebetween.
  • the distribution density of the stripe protrusions on the positive electrode current collector is appropriate, the strength of the positive electrode sheet can be enhanced, the compaction window of the positive electrode sheet is improved, and when preparing a high-pressure compaction positive electrode sheet, it is not easy to have a brittle fracture problem, thereby reducing the brittle fracture of the high-pressure compaction positive electrode sheet, taking into account the energy density and safety performance of the secondary battery.
  • the thickness h2 of the positive electrode material layer is 36 ⁇ m to 61 ⁇ m.
  • h2 can be 36 ⁇ m, 37 ⁇ m, 38 ⁇ m, 39 ⁇ m, 40 ⁇ m, 42 ⁇ m, 44 ⁇ m, 45 ⁇ m, 46 ⁇ m, 48 ⁇ m, 50 ⁇ m, 52 ⁇ m, 54 ⁇ m, 55 ⁇ m, 56 ⁇ m, 58 ⁇ m, 60 ⁇ m, 61 ⁇ m, or a range consisting of any two values therebetween.
  • the striped convex portion design can be used to maximize the energy density, while taking into account the energy density and safety performance of the secondary battery.
  • the thickness h3 of the positive electrode current collector is between 8 ⁇ m and 10 ⁇ m.
  • h3 can be 8 ⁇ m, 9 ⁇ m, 10 ⁇ m, or a range consisting of any two values therebetween.
  • the compacted density PD may be 4.24 g/cm 3 , 4.25 g/cm 3 , 4.26 g/cm 3 , 4.27 g/cm 3 , 4.28 g/cm 3 , 4.29 g/cm 3 , 4.3 g/cm 3 , 4.31 g/cm 3 , 4.32 g/cm 3 , 4.33 g/cm 3 , 4.34 g/cm 3 , 4.35 g/cm 3 , 4.36 g/cm 3 , 4.37 g/cm 3 , 4.38 g/cm 3 , or a range consisting of any two values therebetween.
  • the compaction density PD of the positive electrode material layer is within the above range, indicating that the positive electrode material layer is highly compacted, which is beneficial for obtaining a secondary battery with high energy density.
  • the method for preparing the positive electrode sheet may include, but is not limited to, the following steps: adding an organic material and a conductive material to a solvent and mixing them to obtain a protrusion slurry; applying the protrusion slurry to one or both surfaces of the positive electrode current collector; and drying to form striped protrusions; and further providing a positive electrode material layer to obtain a positive electrode sheet.
  • the above-mentioned solvent may include, but is not limited to, at least one of N-methylpyrrolidone and deionized water.
  • the present application does not impose any particular restrictions on the solid content W of the protrusion slurry, as long as the objectives of the present application can be achieved.
  • the solid content W of the protrusion slurry may be 10% to 40%. It is understood that the striped protrusions may be fully or partially covered by the positive electrode material layer, and the selection can be made as required.
  • the present application does not particularly limit the method for regulating d, L, h1, ⁇ , and ⁇ , as long as the purpose of the present application can be achieved.
  • the size of d, L, and h1 can be regulated by controlling the solid content and coating amount of the protrusion slurry during the coating process, and ⁇ and ⁇ can be regulated by the coating angle and method.
  • the present application has no particular limitation on the positive electrode current collector, as long as the purpose of the present application can be achieved.
  • it may include aluminum foil, aluminum alloy foil or a composite current collector (such as an aluminum-carbon composite current collector).
  • the positive electrode material layer includes a positive electrode active material.
  • the present application has no particular limitation on the positive electrode active material as long as the purpose of the present application can be achieved.
  • the positive electrode active material may include but is not limited to at least one of lithium nickel cobalt manganese oxide (such as NCM811, NCM622, NCM523, NCM111), lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium-rich manganese-based material, lithium cobalt oxide ( LiCoO2 ), lithium manganese oxide, lithium iron manganese phosphate or lithium titanate.
  • the positive electrode material layer may also include a conductive agent and a binder.
  • the present application does not particularly limit the types of the conductive agent and the binder, as long as the purpose of the present application can be achieved.
  • the conductive agent may include but is not limited to at least one of conductive carbon black (Super P), carbon nanotubes (CNTs), carbon fibers, flake graphite, graphene, metal materials or conductive polymers, and the conductive carbon black may include but is not limited to at least one of acetylene black or Ketjen black.
  • the above-mentioned carbon nanotubes may include but are not limited to single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the binder may include, but is not limited to, at least one of polyacrylic acid, sodium polyacrylate, potassium polyacrylate, lithium polyacrylate, polyimide, polyvinyl alcohol, carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyimide, polyamide-imide, styrene-butadiene rubber, or polyvinylidene fluoride.
  • the present application does not particularly limit the mass ratio of the positive electrode active material, conductive agent, and binder in the positive electrode material layer. Those skilled in the art may select the binder according to actual needs, as long as the purpose of the present application can be achieved.
  • the present application has no particular restrictions on the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • it may include copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, foam nickel, foam copper or a composite current collector.
  • the composite current collector can be a lithium-copper composite current collector, a carbon-copper composite current collector, a nickel-copper composite current collector, a titanium-copper composite current collector, etc.
  • the negative electrode material layer may further include a conductive agent and a binder.
  • the present application does not particularly limit the types of the conductive agent and binder, as long as they can achieve the purpose of the present application.
  • they can be at least one of the above-mentioned conductive agents and binders.
  • the present application does not particularly limit the mass ratio of the negative electrode active material, conductive agent, and binder in the negative electrode material layer. Those skilled in the art can select according to actual needs, as long as they can achieve the purpose of the present application.
  • the present application does not particularly limit the thickness of the negative electrode material layer, as long as it can achieve the purpose of the present application.
  • the thickness of the negative electrode material layer is 30 ⁇ m to 120 ⁇ m.
  • the present application does not particularly limit the thickness of the negative electrode current collector, as long as it can achieve the purpose of the present application.
  • the thickness of the negative electrode current collector is 4 ⁇ m to 15 ⁇ m.
  • the present application does not particularly limit the separator, as long as it can achieve the purpose of the present application.
  • the material of the separator may include, but is not limited to, at least one of polyethylene (PE), polypropylene (PP)-based polyolefins (PO), polyesters (e.g., polyethylene terephthalate (PET) film), cellulose, polyimide (PI), polyamide (PA), spandex, or aramid.
  • the type of separator may include at least one of a woven membrane, a non-woven membrane, a microporous membrane, a composite membrane, a rolled membrane, or a spun membrane.
  • the separator may include a substrate layer and a surface treatment layer.
  • the substrate layer may be a non-woven fabric, a film, or a composite film having a porous structure
  • the material of the substrate layer may include at least one of polyethylene, polypropylene, polyethylene terephthalate, or polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film may be used.
  • a surface treatment layer is provided on at least one surface of the substrate layer.
  • the surface treatment layer may be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic layer.
  • the inorganic layer includes inorganic particles and a binder.
  • the application is not particularly limited to inorganic particles.
  • inorganic particles can include at least one of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide or barium sulfate.
  • the application is not particularly limited to the binder.
  • the binder can be at least one of the above-mentioned binders.
  • the polymer layer includes polymer, and the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinyl pyrrolidone, polyvinyl ether or polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
  • the thickness of the separator is not particularly limited as long as the purpose of the present application can be achieved.
  • the thickness of the separator may be 3 ⁇ m to 30 ⁇ m.
  • the secondary battery further includes an electrolyte, and the electrolyte includes a lithium salt and a non-aqueous solvent.
  • the present application does not particularly limit the lithium salt, as long as the objectives of the present application can be achieved.
  • the lithium salt may include, but is not limited to, at least one of LiPF6 , LiBF4 , LiAsF6 , LiClO4 , LiB ( C6H5 ) 4 , LiCH3SO3 , LiCF3SO3 , LiN( SO2CF3 ) 2 , LiC( SO2CF3 ) 3 , Li2SiF6 , lithium bis(oxalatoborate) (LiBOB), or lithium difluoroborate.
  • the present application does not particularly limit the content of the lithium salt in the electrolyte, as long as the objectives of the present application can be achieved.
  • non-aqueous solvents can include but are not limited to at least one of carbonate compounds, carboxylate compounds, ether compounds or other organic solvents.
  • carbonate compounds can include but are not limited to at least one of linear carbonate compounds, cyclic carbonate compounds or fluorinated carbonate compounds.
  • linear carbonate compounds can include but are not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC) or methyl ethyl carbonate (MEC).
  • cyclic carbonates can include but are not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC) or vinyl ethylene carbonate (VEC).
  • the fluorinated carbonate compound may include, but is not limited to, at least one of 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, or trifluoromethylethylene carbonate.
  • FEC fluoroethylene carbonate
  • the above-mentioned carboxylate compound may include, but is not limited to, at least one of methyl formate, methyl acetate, ethyl acetate, n-propyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, decanoic acid lactone, valerolactone, or caprolactone.
  • the above-mentioned ether compound may include but is not limited to at least one of dibutyl ether, tetraglyme, diglyme, 1,2-dimethoxyethane, 1,2-diethoxyethane, 1-ethoxy-1-methoxyethane, 2-methyltetrahydrofuran or tetrahydrofuran.
  • the above-mentioned other organic solvents may include but are not limited to at least one of dimethyl sulfoxide, 1,2-dioxolane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, N-methyl-2-pyrrolidone, dimethylformamide, acetonitrile, trimethyl phosphate, triethyl phosphate or trioctyl phosphate.
  • the present application does not particularly limit the content of the non-aqueous solvent in the electrolyte, as long as the purpose of the present application can be achieved.
  • the secondary battery also includes a shell for accommodating the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte, as well as other components known in the field of secondary batteries.
  • This application does not limit the above-mentioned other components.
  • This application does not particularly limit the shell, and it can be a shell known in the art, as long as it can achieve the purpose of this application.
  • the shell can be a hard shell or a flexible shell.
  • the material of the hard shell can be metal.
  • a metal hard shell known in the art can be used, as long as it can achieve the purpose of this application.
  • the flexible shell can be a metal plastic film, such as an aluminum plastic film, a steel plastic film, etc.
  • the preparation process of the secondary battery of the present application is well known to those skilled in the art and is not particularly limited in the present application.
  • the preparation process of the secondary battery may include but is not limited to the following steps: stacking the positive electrode sheets, the separator and the negative electrode sheets in order, and winding, folding and other operations as needed to obtain an electrode assembly with a wound structure, placing the electrode assembly in a shell, injecting the electrolyte into the shell and sealing it to obtain a secondary battery.
  • the second aspect of the present application provides an electronic device, which includes the secondary battery in any of the aforementioned embodiments. Therefore, the electronic device provided by the present application has good performance.
  • the present application does not particularly limit the type of electronic device, and it can be any electronic device known in the prior art.
  • the electronic device can include, but is not limited to, a laptop computer, a pen-type computer, a mobile computer, an electronic 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 television, 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 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.
  • Winding performance At a conveying speed of 35m/min and a tension of 3MPa, the positive electrode sheet is rolled onto a reel with a diameter of 100mm through a roller until the reel diameter reaches 500mm. If there is no bulging, breakage or damage to the electrode sheet during the process, the winding is normal. Otherwise, the winding is abnormal and the problems are recorded.
  • both the winding performance and the winding inner ring fracture performance are normal, it is recorded as normal processing performance; if one of them is abnormal, it is recorded as risky processing performance.
  • Positive electrode sheet compaction density positive electrode material layer mass per unit area (g/cm 2 ) / positive electrode material layer thickness (cm).
  • the positive electrode material layer mass per unit area can be measured using a balance, and the positive electrode material layer thickness can be measured using a micrometer.
  • the highest compaction density that can be processed for the positive electrode sheets of each embodiment and comparative example is the maximum compaction density at which the positive electrode sheets do not have bulging edges, fractures, breakages, or light-transmitting spots.
  • a 600g flat plate was used to press the lithium-ion battery in the thickness direction, and the actual thickness D of the battery cell was measured with a micrometer.
  • the length L' and width M of the lithium-ion battery were measured by scanning with a laser measuring instrument.
  • the area where the positive electrode sheet has a crease is marked as the corner area, specifically the area extending 2 mm to either side of the crease.
  • S1 can be calculated using the above d, L, and the length of the convex portion of the stripe.
  • S2 4 mm ⁇ the width of the positive electrode material layer, and then S1/S2 is calculated.
  • the organic material polyacrylic acid (PAA) and the conductive material graphite were mixed at a mass ratio X of 19:1, added into N-methylpyrrolidone and mixed evenly to obtain a convex portion slurry with a solid content W of 15% and a viscosity of 15000 mPa.s.
  • the positive electrode active material LiCoO 2 , the conductive agent Super P, and the binder polyvinylidene fluoride were mixed in a mass ratio of 97.9:0.9:1.2, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt %.
  • NMP N-methylpyrrolidone
  • the convex slurry was coated using a micro-gravure process onto one surface of an 8 ⁇ m thick aluminum foil for the positive electrode current collector and dried at 100°C to produce multiple striped convex features on one surface of the foil.
  • the multiple striped convex features were applied only to the surface of the positive electrode current collector corresponding to the first circle of the positive electrode sheet.
  • the negative electrode active material, artificial graphite, the binder, styrene-butadiene rubber, and sodium carboxymethyl cellulose were mixed in a mass ratio of 96:2:2.
  • Deionized water was added as a solvent to form a slurry with a solid content of 45 wt%.
  • the mixture was then stirred evenly in a vacuum mixer to obtain a negative electrode slurry.
  • the negative electrode slurry was evenly coated on one surface of a 6 ⁇ m thick negative electrode current collector copper foil and dried at 120°C to obtain a negative electrode sheet coated on one side with a 100 ⁇ m thick layer of negative electrode active material.
  • the above steps were repeated on the other surface of the copper foil to obtain a negative electrode sheet coated on both sides with a negative electrode active material layer.
  • ethylene carbonate (EC), propylene carbonate (PC), and diethyl carbonate (DEC) were mixed in a mass ratio of 1:1:1 to form an organic solvent.
  • the electrolyte salt LiPF 6 was then added to the organic solvent and mixed thoroughly to form an electrolyte solution.
  • the electrolyte salt concentration was 1.15 mol/L based on the mass of the electrolyte solution, with the remainder being the organic solvent.
  • a porous polyethylene film with a thickness of 5 ⁇ m (supplied by Celgard) was used as the separator.
  • the positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in order, with the separator positioned between the positive and negative electrode sheets to act as a separator, and then wound to form an electrode assembly.
  • the electrode assembly is placed in an aluminum-plastic film packaging bag, dehydrated at 80°C, and then injected with the electrolyte prepared above.
  • the lithium-ion battery is produced through vacuum packaging, standing, forming, degassing, and trimming.
  • the forming temperature is 80°C, and the forming standing time is 2 hours.
  • Example 1 Except for the following steps to prepare the positive electrode sheet, the rest is the same as Example 1:
  • the positive electrode active material LiCoO 2 , the conductive agent Super P, and the binder polyvinylidene fluoride were mixed in a mass ratio of 97.9:0.9:1.2, and N-methylpyrrolidone (NMP) was added as a solvent to prepare a slurry with a solid content of 75 wt %.
  • NMP N-methylpyrrolidone
  • the convex slurry was coated using a micro-gravure process on one surface of an 8 ⁇ m thick aluminum foil for the positive electrode current collector. The process was then dried at 100°C. The above steps were repeated on the other surface of the foil to form multiple striped convex features on both surfaces of the foil.
  • the multiple striped convex features were applied to both surfaces of the positive electrode current collector corresponding to the first circle of the positive electrode sheet.
  • the positive electrode slurry was then applied to the surface of the aluminum foil with the multiple striped protrusions, dried at 120°C, and the above steps were repeated on the other surface of the aluminum foil with the multiple striped protrusions. After cutting and welding the tabs, a positive electrode sheet with a size of 74 mm x 867 mm was obtained for future use.
  • the coating weight CW of the positive electrode material layer was 400 mg/1540 mm2 , and the thickness h2 of the positive electrode material layer was 60 ⁇ m.
  • Example 1 Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1.
  • Example 1 Except for adjusting the relevant preparation parameters according to Table 1, the rest is the same as Example 1.
  • Example 1 Except that the striped protrusions are not provided when preparing the positive electrode plate, the rest is the same as that of Example 1.
  • Example 2 The process is the same as in Example 1, except that the positive electrode slurry is prepared according to the following steps when preparing the positive electrode sheet, and no striped protrusions are provided:
  • the positive electrode plate in the embodiment does not have the problems of bulging edge, broken belt, and brittle fracture of the inner ring, and the unit fracture strength F and the highest processable pressure density are high, which means that the positive electrode plate is not easy to be brittle fractured under high pressure density, and the energy density and safety performance of the obtained lithium-ion battery can also be achieved.
  • the arrangement of the striped protrusions on both surfaces of the positive electrode current collector usually affects the energy density of the lithium-ion battery. It can be seen from Examples 36 to 42 that when the striped protrusions are arranged on both surfaces of the positive electrode current collector and the angle ⁇ is within the scope of this application, the inner circle of the obtained positive electrode plate is normal and the unit fracture strength F and the maximum processable pressure density are high, which means that the positive electrode plate is not easy to break brittlely under high pressure density, and the energy density and safety performance of the obtained lithium-ion battery can also be achieved.

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Abstract

一种二次电池和电子装置，二次电池包括卷绕结构的电极组件，电极组件包括正极极片、负极极片和隔膜，正极极片包括正极集流体和正极材料层；正极极片包括从卷绕中心开始的第一圈的拐角区域，拐角区域设置有位于集流体和正极材料层之间的多个条纹凸部，多个条纹凸部间隔设置；单个条纹凸部与正极极片长度方向的夹角α为20°至70°。通过设置条纹凸部和夹角α在上述范围内，可以提升正极极片的强度和压密窗口，降低高压密正极极片的脆断性，从而兼顾二次电池的能量密度和安全性能。

Description

一种二次电池和电子装置
本申请要求于2024年3月31日提交中国专利局、申请号为202410383479.5、发明名称为“一种二次电池和电子装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电化学技术领域，特别是涉及一种二次电池和电子装置。
背景技术
二次电池，例如锂离子电池，因其具有高能量密度、高动力学、长寿命等特性，被广泛应用于消费类、动力、储能等领域，是现阶段新能源领域最为关注的焦点。随着技术的不断进步和革新，人们对于能量密度的需求越来越迫切。
高能量密度的锂离子电池必然需要较高的极片压密，但是对于卷绕工艺性的电极组件，当压力达到一定程度，正极极片压密提升较小，主要因为压实密度达到一定水平后正极极片较脆，单位抗断裂力强度急剧下降，影响二次电池的安全性能，考虑到后续的极片走带、弯折，裁切等工艺优率，正极极片的高压密和抗脆断性通常难以兼得，二次电池的能量密度和安全性能也难以兼顾。
发明内容
本申请的目的在于提供一种二次电池和电子装置，以降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
需要说明的是，本申请的发明内容中，以锂离子电池作为二次电池的例子来解释本申请，但是本申请的二次电池并不仅限于锂离子电池。具体技术方案如下：
本申请的第一方面提供了一种二次电池，其包括卷绕结构的电极组件，所述电极组件包括正极极片、负极极片和隔膜，所述正极极片包括正极集流体和正极材料层；所述正极极片包括从卷绕中心开始的第一圈的拐角区域，所述拐角区域设置有位于所述集流体和所述正极材料层之间的多个条纹凸部，多个所述条纹凸部间隔设置；单个所述条纹凸部与所述正极极片长度方向的夹角α为20°至70°。在本申请的一些实施方案中，40°≤α≤50°。通过设置条纹凸部和夹角α在上述范围内，可以提升正极极片的强度，降低高压密正极极片的脆断性，从而兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，相邻两个所述条纹凸部之间的间距d为50μm至500μm，单个所述条纹凸部的宽度L为10μm至300μm、高度h1为0.5μm至10μm。在本申请的一些实施方案中，50μm≤d≤200μm，20μm≤L≤50μm，1μm≤h1≤4μm。通过调控d、L、h1在上述范围内，条纹凸部在正极集流体上的分布密度合适，可以增强正极极片的强度，提升正极极片的压密窗口，在制备高压密的正极极片时，其不易存在脆断问题，从而降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，多个所述条纹凸部在所述正极集流体表面正投影的总面积为S1，所述拐角区域中正极集流体的面积为S2，0.057≤S1/S2≤0.500。通过调控S1/S2在上述范围内，条纹凸部在正极集流体上的分布密度合适，可以增强正极极片的强度，提升正极极片的压密窗口，在制备高压密的正极极片时，其不易存在脆断问题，从而降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，单个所述条纹凸部的高度为h1，所述正极材料层的厚度为h2，0.01≤h1/h2≤0.21。通过调控h1/h2的值在上述范围内，可以满足不同涂布面密度下的压实密度提升，既不过设计而占用过多的空间造成收益过小，又不会因设计不足导致压实密度提升窗口不足。
在本申请的一些实施方案中，多个所述条纹凸部包括多个第一条纹和多个第二条纹，多个所述第一条纹设置在所述正极集流体的一个表面，多个所述第二条纹设置在所述正极集流体的另一个表面，单个所述第一条纹与单个所述第二条纹形成的夹角β为40°至140°。在正极集流体的两个表面同时设置第一条纹和第二条纹，可以进一步提高正极极片的强度、提升正极极片的压密窗口，从而在制备高压密的正极极片时，其不易存在脆断问题。同时调控夹角β在上述范围内，可以使正极集流体两面的受力更均匀，强度提升更理想，结合两面得强度优点，可以取得更佳的压密窗口提升效果。从而进一步降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，所述条纹凸部包括有机材料和导电材料，所述有机材料包括聚丙烯腈、聚乙二醇、丁苯橡胶、尼龙、水性聚酰胺树脂、二甲基硅橡胶、聚丙烯酸、聚甲基丙烯酸甲酯或聚偏二氟乙烯中的至少一种，所述导电材料包括石墨、导电纤维中的至少一种，所述有机材料和所述导电材料的质量比为(4至49):1。条纹凸部包括有机材料和导电材料并调控质量比X在上述范围内，在改善高压密正极极片易脆断问题的同时，对正极极片的导电性影响也较小，能够兼顾正极极片的强度和导电性。另外，上述有机材料和导电材料广谱性高，有利于拓宽应用范围。
在本申请的一些实施方案中，所述正极集流体的厚度h3为8μm至10μm。通过调控正极集流体的厚度h3在上述范围内，正极集流体厚度合适，得到的二次电池的能量密度高，而且生产制程优率高，有利于产业化。
在本申请的一些实施方案中，所述正极材料层的压实密度PD大于或等于4.24g/cm3。正极材料层的压实密度PD在上述范围内，说明正极材料层的压密高，从而有利于得到能量密度高的二次电池。
在本申请的一些实施方案中，二次电池满足以下特征中的至少一者：
(1)所述正极材料层的涂布面密度为240mg/1540.25mm2至400mg/1540.25mm2；
(2)所述正极极片的单位抗断裂力强度为150MPa至270MPa；
(3)所述正极材料层的厚度h2为36μm至61μm。
二次电池满足以上特征中的至少一者可以兼顾能量密度和安全性能。
本申请的第二方面提供了一种电子装置，其包含前述任一实施方案中的二次电池。
本申请的有益效果：
本申请提供了一种二次电池和电子装置，二次电池包括卷绕结构的电极组件，电极组件包括正极极片、负极极片和隔膜，正极极片包括正极集流体和正极材料层；正极极片包括从卷绕中心开始的第一圈拐角的拐角区域，拐角区域设置有位于集流体和正极材料层之间的多个条纹凸部，多个条纹凸部间隔设置；单个条纹凸部与正极极片长度方向的夹角α为20°至70°。在本申请的一些实施方案中，40°≤α≤50°。通过设置条纹凸部和夹角α在上述范围内，可以提升正极极片的强度和压密窗口，降低高压密正极极片的脆断性，从而兼顾二次电池的能量密度和安全性能。
当然，实施本申请的任一产品或方法并不一定需要同时达到以上所述的所有优点。
附图说明
此处所说明的附图用来提供对本申请的进一步理解，构成本申请的一部分，本申请的示意性实施例及其说明用于解释本申请，并不构成对本申请的不当限定。
图1为本申请一些实施方案中的电极组件沿自身厚度方向的剖面结构示意图；
图2为本申请一些实施方案中正极极片的局部结构示意图；
图3为本申请一些实施方案中设置有条纹凸部的正极集流体的结构示意图；
图4为本申请另一些实施方案中设置有条纹凸部的正极集流体的结构示意图。
具体实施方式
为使本申请的目的、技术方案、及优点更加清楚明白，以下参照附图并举实施例，对本申请进一步详细说明。显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。本领域技术人员基于本申请所获得的所有其他实施例，都属于本申请保护的范围。
需要说明的是，本申请的具体实施方式中，以锂离子电池作为二次电池的例子来解释本申请，但是本申请的二次电池并不仅限于锂离子电池。
目前，在解决高压密正极极片易脆断问题时通常采用以下几种方法：在正极材料层中加入添加剂以软化正极材料层，或者采用高强度的正极集流体。在材料层中加入添加剂，例如石蜡、甘油、片层石墨等，其在一定程度上可以软化正极材料层并提升其压密，但通常会导致粘结剂失效，影响二次电池的安全性能。高强度的正极集流体对于提升压密、改善脆断问题有限，而且其厚度通常较厚，会影响二次电池的能量密度。
基于上述问题，本申请提供了一种二次电池和电子装置，降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
本申请的第一方面提供了一种二次电池，其包括卷绕结构的电极组件，如图1和图2所示，电极组件包括正极极片10、负极极片20和隔膜30，正极极片10包括正极集流体11和正极材料层12，正极材料层12设置在正极集流体11的两个表面上。正极极片10包括从卷绕中心开始的第一圈拐角的拐角区域13，拐角区域13设置有位于正极集流体11和正极材料层12之间的多个条纹凸部14，多个条纹凸部14间隔设置。正极极片10从卷绕中心开始的第一圈也即线段A-A’之间的区域卷绕形成，第一圈的拐角区域13也即线段B-B’之间的区域。如图3所示，单个条纹凸部14与正极极片长度方向的夹角α为20°至70°。在本申请的一些实施方案中，40°≤α≤50°。例如，夹角α可以为20°、25°、30°、35°、40°、45°、50°、55°、60°、65°、70°或为其间任意两个数值组成的范围。条纹凸部设置在正极集流体上且存在夹角α，可以增强正极极片的强度，提升正极极片的压密窗口，从而在制备高压密的正极极片时，其不易存在脆断问题。当夹角α过小时，例如小于20°，条纹凸起和长度方向角度差小，正极极片收卷过程易在固定区域形成凸棱鼓起而断带；当夹角α过大时，例如大于70°，条纹凸起和长度方向角度差过大，压实密度提升后，在卷绕正极极片弯折时，条纹凸起层无法分担正极集流体的弯折变形力，导致正极极片弯折断裂，以致压实密度窗口无法提升。从而，通过设置条纹凸部和夹角α在上述范围内，可以提升正极极片的强度和压密窗口，降低高压密正极极片的脆断性，从而兼顾二次电池的能量密度和安全性能。
在本申请中，卷绕电极组件从卷绕中心开始的第一圈中，正极极片有折痕的区域记为拐角区域，具体为折痕往两侧延伸2mm的区域。
在本申请的一些实施方案中，正极极片第一圈中除拐角区域的其它区域也可以设置多个条纹涂部，更有利于工业化生产。在本申请的一些实施方案中，正极极片第一圈和第二圈的拐角区域均设置多个条纹涂部，可以进一步降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
在本申请中，多个条纹凸部也即各个条纹平行分布；正极极片长度方向也即正极极片的较长边所在的方向；高压密正极极片是指正极材料层压实密度大于4.24g/cm3的正极极片。
在本申请的一些实施方案中，相邻两个条纹凸部之间的间距d为50μm至500μm，单个条纹凸部的宽度L为10μm至300μm、高度h1为0.5μm至10μm。在本申请的一些实施方案中，50μm≤d≤200μm，20μm≤L≤50μm，1μm≤h1≤4μm。例如，d可以为50μm、60μm、70μm、80μm、90μm、100μm、120μm、140μm、150μm、170μm、190μm、200μm、250μm、300μm、350μm、400μm、450μm或为其间任意两个数值组成的范围。例如，L可以为10μm、15μm、20μm、25μm、30μm、35μm、40μm、45μm、50μm、60μm、70μm、80μm、90μm、100μm、125μm、150μm、175μm、200μm、225μm、250μm、275μm、300μm或为其间任意两个数值组成的范围。例如，h1可以为0.5μm、1μm、1.5μm、2μm、2.5μm、3μm、3.5μm、4μm、4.5μm、5μm、5.5μm、6μm、6.5μm、7μm、7.5μm、8μm、8.5μm、9μm、9.5μm、10μm或为其间任意两个数值组成的范围。通过调控d、L、h1在上述范围内，条纹凸部在正极集流体上的分布密度合适，可以增强正极极片的强度，提升正极极片的压密窗口，在制备高压密的正极极片时，其不易存在脆断问题，从而降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，多个条纹凸部在正极集流体表面正投影的总面积为S1，拐角区域中正极集流体的面积为S2，0.057≤S1/S2≤0.500。例如，S1/S2可以为0.057、0.060、0.070、0.080、0.090、0.100、0.150、0.200、0.250、0.300、0.350、0.400、0.450、0.500或为其间任意两个数值组成的范围。通过调控S1/S2在上述范围内，条纹凸部在正极集流体上的分布密度合适，可以增强正极极片的强度，提升正极极片的压密窗口，在制备高压密的正极极片时，其不易存在脆断问题，从而降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，单个条纹凸部的高度为h1，正极材料层的厚度为h2，0.01≤h1/h2≤0.21。例如，h1/h2可以为0.01、0.02、0.03、0.04、0.05、0.06、0.07、0.08、0.09、0.1、0.11、0.12、0.13、0.14、0.15、0.16、0.17、0.18、0.19、0.20、0.21或为其间任意两个数值组成的范围。通过调控h1/h2的值在上述范围内，可以满足不同涂布面密度下的压实密度提升，既不过设计而占用过多的空间造成收益过小，又不会因设计不足导致压实密度提升窗口不足。
在本申请的一些实施方案中，正极材料层的厚度h2为36μm至61μm。例如，h2可以为36μm、37μm、38μm、39μm、40μm、42μm、44μm、45μm、46μm、48μm、50μm、52μm、54μm、55μm、56μm、58μm、60μm、61μm或为其间任意两个数值组成的范围。通过调控正极材料层的厚度h2在上述范围内，可以通过条纹凸部设计获得最大限度的能量密度提升，兼顾二次电池的能量密度和安全性能。
在本申请的一些实施方案中，如图4所示，多个条纹凸部14包括多个第一条纹141和多个第二条纹142，多个第一条纹141设置在正极集流体11的一个表面，多个第二条纹142设置在正极集流体11的另一个表面，单个第一条纹与单个第二条纹形成的夹角β为40°至140°。例如，夹角β可以为40°、50°、60°、70°、80°、90°、100°、110°、120°、130°、140°或为其间任意两个数值组成的范围。在正极集流体的两个表面同时设置第一条纹和第二条纹，可以进一步提高正极极片的强度、提升正极极片的压密窗口，从而在制备高压密的正极极片时，其不易存在脆断问题。同时调控夹角β在上述范围内，可以使正极集流体两面的受力更均匀，强度提升更理想，结合两面得强度优点，可以取得更佳的压密窗口提升效果。从而进一步降低高压密正极极片的脆断性，兼顾二次电池的能量密度和安全性能。在本申请中，夹角β是指沿正极极片厚度方向单个第一条纹的正投影与单个第二条纹正投影的夹角。
在本申请的一些实施方案中，条纹凸部包括有机材料和导电材料，有机材料包括聚丙烯腈、聚乙二醇、丁苯橡胶、尼龙、水性聚酰胺树脂、二甲基硅橡胶、聚丙烯酸、聚甲基丙烯酸甲酯或聚偏二氟乙烯中的至少一种，导电材料包括石墨、导电纤维中的至少一种，有机材料和导电材料的质量比X为(4至49):1。例如，质量比X可以为4:1、5:1、10:1、15:1、20:1、25:1、30:1、35:1、40:1、45:1、49:1或为其间任意两个比值组成的范围。条纹凸部包括有机材料和导电材料并调控质量比X在上述范围内，在改善高压密正极极片易脆断问题的同时，对正极极片的导电性影响也较小，能够兼顾正极极片的强度和导电性。另外，上述有机材料和导电材料广谱性高，有利于拓宽应用范围。
在本申请的一些实施方案中，导电纤维可以包括但不限于碳纳米管(CNTs)、碳纤维、或导电聚合物纤维中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述导电聚合物纤维可以包括但不限于以下化合物中的至少一种形成的纤维：聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯。
在本申请的一些实施方案中，正极集流体的厚度h3为8μm至10μm。例如，h3可以为8μm、9μm、10μm或为其间任意两个数值组成的范围。通过调控正极集流体的厚度h3在上述范围内，正极集流体厚度合适，得到的二次电池的能量密度高，而且生产制程优率高，有利于产业化。
在本申请的一些实施方案中，正极材料层的压实密度PD大于或等于4.24g/cm3。在本申请的一些实施方案中，正极材料层的压实密度PD为4.24g/cm3至4.38g/cm3。例如，压实密度PD可以为4.24g/cm3、4.25g/cm3、4.26g/cm3、4.27g/cm3、4.28g/cm3、4.29g/cm3、4.3g/cm3、4.31g/cm3、4.32g/cm3、4.33g/cm3、4.34g/cm3、4.35g/cm3、4.36g/cm3、4.37g/cm3、4.38g/cm3或为其间任意两个数值组成的范围。正极材料层的压实密度PD在上述范围内，说明正极材料层的压密高，从而有利于得到能量密度高的二次电池。
在本申请的一些实施方案中，正极材料层的涂布面密度CW为240mg/1540.25mm2至400mg/1540.25mm2。例如，涂布面密度CW可以为240mg/1540.25mm2、250mg/1540.25mm2、260mg/1540.25mm2、270mg/1540.25mm2、280mg/1540.25mm2、290mg/1540.25mm2、300mg/1540.25mm2、310mg/1540.25mm2、320mg/1540.25mm2、330mg/1540.25mm2、340mg/1540.25mm2、350mg/1540.25mm2、360mg/1540.25mm2、370mg/1540.25mm2、380mg/1540.25mm2、390mg/1540.25mm2、400mg/1540.25mm2或为其间任意两个数值组成的范围。正极材料层的涂布面密度CW在上述范围内，说明正极材料层的涂布面密度高，从而有利于得到能量密度高的二次电池。
在本申请的一些实施方案中，正极极片的单位抗断裂力强度F为150MPa至270MPa。例如，单位抗断裂力强度F可以为150MPa、160MPa、170MPa、180MPa、190MPa、210MPa、220MPa、230MPa、240MPa、250MPa、260MPa、270MPa或为其间任意两个数值组成的范围。正极极片的单位抗断裂力强度在上述范围内，说明其具有高的强度，有利于提高二次电池的安全性能。
本申请对正极极片的制备方法没有特别限制，只要能实现本申请的目的即可，示例性地，正极极片的制备方法可以包括但不限于以下步骤：将有机材料和导电材料加入溶剂混合，得到凸部浆料，将凸部浆料涂覆在正极集流体的一个表面或两个表面，烘干形成条纹凸部；继续设置正极材料层，得到正极极片。其中，上述溶剂可以包括但不限于N-甲基吡咯烷酮或去离子水中的至少一种。本申请对凸部浆料的固含量W没有特别限制，只要能实现本申请的目的即可，示例性地，凸部浆料的固含量W可以为10％至40％。可以理解的是，条纹凸部可以被正极材料层全部覆盖或部分覆盖，可以根据所需进行选择。
本申请对调控d、L、h1、α、β的方式没有特别限制，只要能实现本申请的目的即可。示例性地，d、L、h1的大小可以通过调控涂覆过程中凸部浆料的固含量和涂覆量来进行调控，α、β可以通过涂覆的角度、方式来进行调控。
本申请对正极集流体没有特别限制，只要能够实现本申请目的即可，例如，可以包含铝箔、铝合金箔或复合集流体(例如铝碳复合集流体)等。
正极材料层包括正极活性材料，本申请对正极活性材料没有特别限制，只要能够实现本申请目的即可，例如，正极活性材料可以包含但不限于镍钴锰酸锂(例如NCM811、NCM622、NCM523、NCM111)、镍钴铝酸锂、磷酸铁锂、富锂锰基材料、钴酸锂(LiCoO2)、锰酸锂、磷酸锰铁锂或钛酸锂中的至少一种。
正极材料层还可以包括导电剂和粘结剂，本申请对导电剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可。例如，导电剂可以包括但不限于导电炭黑(Super P)、碳纳米管(CNTs)、碳纤维、鳞片石墨、石墨烯、金属材料或导电聚合物中的至少一种，导电炭黑可以包括但不限于乙炔黑或科琴黑中的至少一种。上述碳纳米管可以包括但不限于单壁碳纳米管和/或多壁碳纳米管。上述碳纤维可以包括但不限于气相生长碳纤维(VGCF)和/或纳米碳纤维。上述金属材料可以包括但不限于金属粉和/或金属纤维，具体地，金属可以包括但不限于铜、镍、铝或银中的至少一种。上述导电聚合物可以包括但不限于聚亚苯基衍生物、聚苯胺、聚噻吩、聚乙炔或聚吡咯中的至少一种。粘结剂可以包括但不限于聚丙烯酸、聚丙烯酸钠、聚丙烯酸钾、聚丙烯酸锂、聚酰亚胺、聚乙烯醇、羧甲基纤维素、羧甲基纤维素钠、羧甲基纤维素锂、聚酰亚胺、聚酰胺酰亚胺、丁苯橡胶或聚偏二氟乙烯中的至少一种。本申请对正极材料层中正极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。
在本申请中，负极极片包括负极集流体以及设置于负极集流体至少一个表面上的负极材料层。上述“负极材料层设置于负极集流体至少一个表面上”是指，负极材料层可以设置于负极集流体沿自身厚度方向上的一个表面上，也可以设置于负极集流体沿自身厚度方向上的两个表面上。需要说明，这里的“表面”可以是负极集流体表面的全部区域，也可以是负极集流体表面的部分区域，本申请没有特别限制，只要能实现本申请目的即可。
本申请对负极集流体没有特别限制，只要能够实现本申请目的即可，例如，可以包含铜箔、铜合金箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或复合集流体，示例性地，复合集流体可以为锂铜复合集流体、碳铜复合集流体、镍铜复合集流体、钛铜复合集流体等。
负极材料层包括负极活性材料，本申请对负极活性材料没有特别限制，只要能够实现本申请目的即可，例如，负极活性材料可以包含但不限于天然石墨、人造石墨、中间相微碳球、硬碳、软碳、硅、硅-碳复合物、Li-Sn合金、Li-Sn-O合金、Sn、SnO、SnO2、尖晶石结构的锂化TiO2-Li4Ti5O12或Li-Al合金中的至少一种。
在本申请的一些实施方案中，负极材料层还可以包括导电剂和粘结剂，本申请对导电剂和粘结剂的种类没有特别限制，只要能够实现本申请目的即可，例如，可以是上述导电剂和上述粘结剂中的至少一种。本申请对负极材料层中负极活性材料、导电剂、粘结剂的质量比没有特别限制，本领域技术人员可以根据实际需要选择，只要能够实现本申请目的即可。
本申请对负极材料层的厚度没有特别限制，只要能够实现本申请目的即可，例如，负极材料层的厚度为30μm至120μm。本申请对负极集流体的厚度没有特别限制，只要能够实现本申请目的即可，例如，负极集流体的厚度为4μm至15μm。
任选地，负极极片还可以包含导电层，导电层位于负极集流体和负极材料层之间。本申请对导电层的组成没有特别限制，可以是本领域常用的导电层。例如，导电层包括导电剂和粘结剂。本申请对导电层中的导电剂和粘结剂没有特别限制，例如可以是上述导电剂和上述粘结剂中的至少一种。
本申请对隔膜没有特别限制，只要能够实现本申请目的即可。例如，隔膜的材料可以包括但不限于聚乙烯(PE)、聚丙烯(PP)为主的聚烯烃(PO)类、聚酯(例如，聚对苯二甲酸二乙酯(PET)膜)、纤维素、聚酰亚胺(PI)、聚酰胺(PA)、氨纶或芳纶中的至少一种。隔膜的类型可以包括织造膜、非织造膜、微孔膜、复合膜、碾压膜或纺丝膜中的至少一种。
在本申请的一些实施方案中，隔膜可以包括基材层和表面处理层。基材层可以为具有多孔结构的无纺布、膜或复合膜，基材层的材料可以包括聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯或聚酰亚胺中的至少一种。任选地，可以使用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
任选地，基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
在本申请的一些实施方案中，无机物层包括无机颗粒和粘结剂。本申请对无机颗粒没有特别限制，例如无机颗粒可以包括氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙或硫酸钡中的至少一种。本申请对粘结剂没有特别限制，例如粘结剂可以是上述粘结剂中的至少一种。在本申请的一些实施方案中，聚合物层包括聚合物，聚合物的材料包括聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯吡咯烷酮、聚乙烯醚或聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的至少一种。
在本申请中，隔膜的厚度没有特别限制，只要能实现本申请的目的即可，例如隔膜的厚度可以为3μm至30μm。
在本申请中，二次电池还包括电解液，电解液包括锂盐和非水溶剂。
本申请对锂盐没有特别限制，只要能实现本申请的目的即可。例如锂盐可以包括但不限于LiPF6、LiBF4、LiAsF6、LiClO4、LiB(C6H5)4、LiCH3SO3、LiCF3SO3、LiN(SO2CF3)2、LiC(SO2CF3)3、Li2SiF6、双草酸硼酸锂(LiBOB)或二氟硼酸锂中的至少一种。本申请对锂盐在电解液中的含量没有特别限制，只要能实现本申请的目的即可。
本申请对非水溶剂没有特别限制，只要能实现本申请的目的即可，例如非水溶剂可以包括但不限于碳酸酯化合物、羧酸酯化合物、醚化合物或其它有机溶剂中的至少一种。上述碳酸酯化合物可以包括但不限于链状碳酸酯化合物、环状碳酸酯化合物或氟代碳酸酯化合物中的至少一种。上述链状碳酸酯化合物可以包括但不限于碳酸二甲酯(DMC)、碳酸二乙酯(DEC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)或碳酸甲乙酯(MEC)中的至少一种。上述环状碳酸酯可以包括但不限于碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸亚丁酯(BC)或碳酸乙烯基亚乙酯(VEC)中的至少一种。氟代碳酸酯化合物可以包括但不限于氟代碳酸乙烯酯(FEC)、碳酸1,2-二氟亚乙酯、碳酸1,1-二氟亚乙酯、碳酸1,1,2-三氟亚乙酯、碳酸1,1,2,2-四氟亚乙酯、碳酸1-氟-2-甲基亚乙酯、碳酸1-氟-1-甲基亚乙酯、碳酸1,2-二氟-1-甲基亚乙酯、碳酸1,1,2-三氟-2-甲基亚乙酯或碳酸三氟甲基亚乙酯中的至少一种。上述羧酸酯化合物可以包括但不限于甲酸甲酯、乙酸甲酯、乙酸乙酯、乙酸正丙酯、乙酸叔丁酯、丙酸甲酯、丙酸乙酯、丙酸丙酯、γ-丁内酯、癸内酯、戊内酯或己内酯中的至少一种。上述醚化合物可以包括但不限于二丁醚、四甘醇二甲醚、二甘醇二甲醚、1,2-二甲氧基乙烷、1,2-二乙氧基乙烷、1-乙氧基-1-甲氧基乙烷、2-甲基四氢呋喃或四氢呋喃中的至少一种。上述其它有机溶剂可以包括但不限于二甲亚砜、1,2-二氧戊环、环丁砜、甲基环丁砜、1,3-二甲基-2-咪唑烷酮、N-甲基-2-吡咯烷酮、二甲基甲酰胺、乙腈、磷酸三甲酯、磷酸三乙酯或磷酸三辛酯中的至少一种。本申请对非水溶剂在电解液中的含量没有特别限制，只要能实现本申请的目的即可。
二次电池还包括壳体，用于容纳正极极片、隔膜、负极极片和电解液，以及二次电池领域中已知的其它部件，本申请对上述其它部件不做限定。本申请对壳体没有特别限制，可以为本领域公知的壳体，只要能够实现本申请目的即可。例如，壳体可以为硬壳壳体或柔性壳体。硬壳壳体的材料可以为金属，本申请对金属的种类不做限定，可以采用本领域已知的金属硬壳壳体，只要能实现本申请的目的即可。柔性壳体可以为金属塑膜，例如铝塑膜、钢塑膜等。
本申请的二次电池的制备过程为本领域技术人员所熟知的，本申请没有特别的限制，例如，二次电池的制备过程可以包括但不限于以下步骤：将正极极片、隔膜和负极极片按顺序堆叠，并根据需要将其卷绕、折叠等操作得到卷绕结构的电极组件，将电极组件放入壳体内，将电解液注入壳体并封口，得到二次电池。或者，将正极极片、隔膜和负极极片按顺序堆叠，然后用胶带将整个叠片结构的四个角固定好得到叠片结构的电极组件，将电极组件置入壳体内，将电解液注入壳体并封口，得到二次电池。此外，也可以根据需要将防过电流元件、导板等置于壳体中，从而防止二次电池内部的压力上升、过充放电。
本申请的第二方面提供了一种电子装置，其包括前述任一实施方案中的二次电池。从而，本申请提供的电子装置具有良好的使用性能。
本申请对电子装置的种类没有特别限定，其可以是用于现有技术中已知的任何电子装置。在本申请的一些实施方案中，电子装置可以包括但不限于笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池和锂离子电容器等。
实施例
以下，举出实施例及对比例来对本申请的实施方式进行更具体地说明。各种的试验及评价按照下述的方法进行。另外，只要无特别说明，“份”、“％”为质量基准。
测试方法和设备：
正极极片的单位抗断裂力强度测试：
(1)将待测正极极片，用刀片裁切为宽度为20mmХ200mm的长条形，并确认边缘无明显毛刺；
(2)打开三思拉力机电源，指示灯亮，调整限位块到合适位置；
(3)将裁切好的正极极片的两端分别夹持在拉力机的两个夹子上；
(4)设置10mm/min速度，测试范围0mm至100mm，180°平直开始拉动正极极片，直至拉断，测试结束；
(5)根据软件提示保存单位抗断裂力强度测试数据。
加工性能测试：
收卷性能：在走带速度35m/min下，极片在张力为3MPa下，将正极极片经过辊收卷在直径为100mm的卷筒上，直至卷筒直径至500mm为止，过程不出现极片鼓边、断裂、破损即为收卷正常，否则为收卷异常，并记录存在的问题。
卷绕内圈断裂：
1)将隔膜、正极极片、隔膜、负极极片层叠经卷绕做成干电芯后，在压强为0.5Mpa的面压下压实5s，
2)然后将干电芯拆开至有正极材料层弯折的最内圈，将正极极片最内层折痕处在强光下确认，将>200μm的透光孔记为1个透光点，分级判断标准：
a.透光点有1至3个为临界透光，记为内圈临界脆断；
b.透光点>3个或单个透光点＞2mm的记为内圈脆断；
c.将没有透光点的记为内圈正常；
将收卷性能和卷绕内圈断裂性能均正常的记为加工性能正常；将有一项为非正常情况记为加工性能有风险。
直流内阻测试：
将锂离子电池在25℃高低温箱中静置4h；以0.1C恒流充电至电压为4.5V，然后以4.5V恒压充电至截止电流0.05C，静置10min；然后以0.2C电流放电10s，此时电压记为V1，电流为I1；然后以1C恒流放电1s，此时电压记为V2，电流为I2；则将R＝(V1-V2)/(I1-I2)记为锂离子电池对应的直流内阻。当直流内阻小于80mΩ时，记为电阻正常；当直流内阻大于或等于80mΩ时，记为内阻偏大。
正极极片压实密度PD的测试：
正极极片压实密度＝单位面积正极材料层质量(单位为g/cm2)/正极材料层厚度(单位为cm)。单位面积正极材料层质量可以通过天平称量，正极材料层厚度可通过万分尺测量。
各实施例和对比例的正极极片可加工的最高压实密度为正极极片不出现鼓边、断裂、破损和透光点的最大压实密度。
能量密度测试：
将锂离子电池置于25℃的环境中，以1C恒流充电至电压为4.5V，之后以4.5V恒压充电至截止电流0.2C，静置5min，以0.2C恒流放电至电压为3.0V，静置5min，记录此时的放电容量为C，记录恒流电流值为I。
用重量600g的平板将锂离子电池沿厚度方向压持，用万分尺测量电芯的实际厚度D；使用激光测量仪扫描测的锂离子电池的长度L’和宽度M。
则锂离子电池的实际能量密度为：X＝C×I/(D×L’×M)；
能量密度收益率记为Y：Y＝(X-X0)/X0×100％
其中，X0为对比例3中的锂离子电池的能量密度，X为各实施例或对比例中锂离子电池的能量密度。
挤压安全性能测试：
(1)将待测锂离子电池置于25℃的环境中，以0.5C恒流充电至电压为4.5V，之后以4.5V恒压充电至截止电流0.05C，静置5min，为满充状态；
(2)测试前后检查外观并拍照；
(3)在20±5℃测试环境，将锂离子电池放置于测试台面，使用25mm的圆棒放置于锂离子电池中心位置，挤压力5±0.78KN，挤压速度0.1mm/s，挤压力达到设定值保持10s，达到以下条件之一结束：爆炸、冒烟、起火；
(4)测试过程监控锂离子电池的电压内阻，测量使用1KHZ规格；
(5)判定标准:不爆炸、不冒烟、不起火、电压降<1.5V；
每个实施例或对比例测试10个锂离子电池，记录通过的个数，记作：通过数/实验数，如9/10为测试10个锂离子电池，9个通过测试。
d、L、h1、α、β的测量：
将锂离子电池拆解，将正极极片沿自身厚度方向的横截面经过离子抛光，观察凸部，选取其中一个可以测量其d、L、h1。将正极极片放在NMP溶液里浸泡4h，然后使用超声将正极活性层去除只留下正极集流体以及表面的条纹凸部或条纹凸部的印迹，通过条纹凸部或条纹凸部的印迹可以测量其α、β和条纹凸部的长度。上述尺寸测量均测10个，取平均值作为最终结果。
卷绕电极组件从卷绕中心开始的第一圈中，正极极片有折痕的区域记为拐角区域，具体为折痕往两侧延伸2mm的区域。通过以上d、L、条纹凸部的长度可以计算得到S1。S2＝4mm×正极材料层宽度，进而计算得到S1/S2。
实施例1
<正极极片的制备>
将有机材料聚丙烯酸(PAA)和导电材料石墨按照质量比X为19:1混合，加入N-甲基吡咯烷酮中混合均匀，得到固含量W为15％的凸部浆料，粘度为15000mPa.s。
将正极活性材料LiCoO2、导电剂Super P、粘结剂聚偏二氟乙烯按照质量比97.9:0.9:1.2进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75wt％的浆料，真空搅拌均匀后得到正极浆料。
将凸部浆料采用微凹版工艺涂覆在厚度h3为8μm的正极集流体铝箔的一个表面上，100℃下烘干，得到设置在铝箔一个表面的多个条纹凸部。其中，d＝100μm、L＝30μm、h1＝2μm、α＝45°，多个条纹凸部仅设置在正极极片的第一圈所对应的正极集流体的一个表面上。
然后在设置有多个条纹凸部的铝箔表面继续涂覆正极浆料，120℃条件下烘干，然后在铝箔的另一个表面上涂覆正极浆料，120℃条件下烘干后冷压，再经裁片、焊接极耳，得到规格为74mm×867mm的正极极片待用。其中，正极材料层的涂布重量CW为320mg/1540mm2，正极材料层的厚度h2为48μm。
<负极极片的制备>
将负极活性材料人造石墨、粘结剂丁苯橡胶、羧甲基纤维素钠按照质量比96:2:2进行混合，加入去离子水作为溶剂，调配成为固含量为45wt％的浆料，真空搅拌机搅拌均匀后得到负极浆料。将负极浆料均匀涂覆于厚度为6μm的负极集流体铜箔的一个表面上，120℃条件下烘干，得到单面涂布100μm厚的负极活性材料层的负极极片。然后在铜箔的另一个表面上重复以上步骤，即得到双面涂布负极活性材料层的负极极片。120℃条件下烘干后冷压，再经裁片、焊接极耳，得到规格为78mm×875mm的负极极片待用。其中，单面负极材料层的厚度为54.5μm。
<电解液的制备>
在含水量小于10ppm的环境下，将碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)按照质量比为1:1:1混合得到有机溶剂，然后向有机溶剂中加入电解质盐LiPF6，混合均匀，得到电解液。其中，基于电解液的质量，电解质盐的浓度为1.15mol/L，其余为有机溶剂。
<隔膜>
采用厚度为5μm的多孔聚乙烯薄膜(Celgard公司提供)作为隔膜。
<锂离子电池的制备>
将上述制备的正极极片、隔膜、负极极片按顺序叠好，使隔膜处于正极极片和负极极片中间起到隔离的作用，卷绕得到电极组件。将电极组件装入铝塑膜包装袋中，并在80℃下脱去水分，注入上述制备得到的电解液，经过真空封装、静置、化成、脱气、切边等工序得到锂离子电池。其中，化成温度为80℃，化成静置时间为2h。
实施例2至实施例35、实施例43至实施例46
除了按照表1调整相关制备参数以外，其余与实施例1相同。当有机材料和导电材料的质量比X发生变化时，有机材料和导电材料的总质量不变，质量比按照表1所示变化。
实施例36
除了以下步骤制备正极极片以外，其余与实施例1相同：
<正极极片的制备>
将有机材料聚丙烯酸(PAA)和导电材料石墨按照质量比X为19:1混合，加入N-甲基吡咯烷酮中混合均匀，得到固含量W为15％的凸部浆料，粘度为15000mpa.s。
将正极活性材料LiCoO2、导电剂Super P、粘结剂聚偏二氟乙烯按照质量比97.9:0.9:1.2进行混合，加入N-甲基吡咯烷酮(NMP)作为溶剂，调配成为固含量为75wt％的浆料，真空搅拌均匀后得到正极浆料。
将凸部浆料采用微凹版工艺涂覆在厚度h3为8μm的正极集流体铝箔的一个表面上，100℃下烘干，在铝箔的另一个表面重复上述步骤，得到设置在铝箔两个表面的多个条纹凸部。其中，d＝50μm、L＝40μm、h1＝2μm、α＝45°、β＝40°，多个条纹凸部设置在正极极片的第一圈所对应的正极集流体的两个表面上。
然后在设置有多个条纹凸部的铝箔表面继续涂覆正极浆料，120℃条件下烘干，然后在设置有多个条纹凸部的铝箔的另一个表面重复上述步骤，再经裁片、焊接极耳，得到规格为74mm×867mm的正极极片待用。其中，正极材料层的涂布重量CW为400mg/1540mm2，正极材料层的厚度h2为60μm。
实施例37至实施例42
除了按照表1调整相关制备参数以外，其余与实施例1相同。
实施例47
除了制备正极极片时多个条纹凸部仅设置在正极极片的第一圈和第二圈所对应的正极集流体的一个表面上以外，其余与实施例1相同。
对比例1至对比例2
除了按照表1调整相关制备参数以外，其余与实施例1相同。
对比例3
除了在制备正极极片时不设置条纹凸起以外，其余与实施例1相同。
对比例4
除了在制备正极极片时按照以下步骤制备正极浆料，而且不设置条纹凸起以外，其余与实施例1相同：
将正极活性材料LiCoO2、导电剂Super P、粘结剂聚偏二氟乙烯、润滑添加剂甘油按照质量比96.9:0.9:1.2:1进行混合，加入N-甲基吡咯烷酮作为溶剂，调配成为固含量为75wt％的浆料，真空搅拌均匀后得到正极浆料。
各实施例和对比例的制备参数及性能测试如表1所示。


从实施例1至实施例47、对比例1至对比例4可以看出，实施例中的正极极片中均设置有条纹凸部，且夹角α在本申请的范围内，对比例1和对比例2的夹角α不在本申请的范围内，对比例3未设置条纹凸部，对比例4中的正极极片在制备时加入了甘油以提高材料层的柔韧性，改善高压密正极极片易脆断的问题。对比例1得到的正极极片存在鼓边断带问题，无法正常生产，因此没有对应的锂离子电池性能；对比例2中的正极极片存在内圈脆断的问题而且可加工的最高压密低，锂离子电池的能量密度收益率为负，锂离子电池的能量密度和安全性能不能兼得；对比例3中的正极极片存在内圈脆断的问题而且可加工的最高压密低，锂离子电池安全性能差；对比例4中的锂离子电池能量密度收益率为负，锂离子电池的能量密度和安全性能均较差。而实施例中的正极极片，不存在鼓边、断带、内圈脆断的问题，而且单位抗断裂力强度F和可加工的最高压密高，从而说明正极极片在高压密下不易脆断，得到的锂离子电池的能量密度和安全性能也可以兼得。
条纹凸部的尺寸和设置通常会影响锂离子电池的能量密度，从实施例15至实施例35可以看出，当d、L、h1、h1/h2、S1/S2在本申请的范围内，得到的正极极片内圈正常而且单位抗断裂力强度F和可加工的最高压密高，从而说明正极极片在高压密下不易脆断，得到的锂离子电池的能量密度和安全性能也可以兼得。
条纹凸部中的材料通常会影响锂离子电池的能量密度和内阻，从实施例8至实施例11、实施例43至实施例46可以看出，当有机材料的种类、有机材料和导电材料的质量比X在本申请的范围内，得到的正极极片内圈正常而且单位抗断裂力强度F和可加工的最高压密高，从而说明正极极片在高压密下不易脆断，得到的锂离子电池的内阻正常，能量密度和安全性能也可以兼得。
条纹凸部的在正极集流体的两个表面设置通常会影响锂离子电池的能量密度，从实施例36至实施例42可以看出，当条纹凸部的在正极集流体的两个表面设置而且夹角β在本申请的范围内，得到的正极极片内圈正常而且单位抗断裂力强度F和可加工的最高压密高，从而说明正极极片在高压密下不易脆断，得到的锂离子电池的能量密度和安全性能也可以兼得。
以上所述仅为本申请的较佳实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (12)

  1. 一种二次电池，其包括卷绕结构的电极组件，所述电极组件包括正极极片、负极极片和隔膜，所述正极极片包括正极集流体和正极材料层；
    所述正极极片包括从卷绕中心开始的第一圈的拐角区域，所述拐角区域设置有位于所述集流体和所述正极材料层之间的多个条纹凸部，多个所述条纹凸部间隔设置；单个所述条纹凸部与所述正极极片长度方向的夹角α为20°至70°。
  2. 根据权利要求1所述的二次电池，其中，40°≤α≤50°。
  3. 根据权利要求1所述的二次电池，其中，相邻两个所述条纹凸部之间的间距d为50μm至500μm，单个所述条纹凸部的宽度L为10μm至300μm、高度h1为0.5μm至10μm。
  4. 根据权利要求3所述的二次电池，其中，50μm≤d≤200μm，20μm≤L≤50μm，1μm≤h1≤4μm。
  5. 根据权利要求1至4中任一项所述的二次电池，其中，多个所述条纹凸部在所述正极集流体表面正投影的总面积为S1，所述拐角区域中正极集流体的面积为S2，0.057≤S1/S2≤0.500。
  6. 根据权利要求1至4中任一项所述的二次电池，其中，单个所述条纹凸部的高度为h1，所述正极材料层的厚度为h2，0.01≤h1/h2≤0.21。
  7. 根据权利要求1至4中任一项所述的二次电池，其中，多个所述条纹凸部包括多个第一条纹和多个第二条纹，多个所述第一条纹设置在所述正极集流体的一个表面，多个所述第二条纹设置在所述正极集流体的另一个表面，单个所述第一条纹与单个所述第二条纹形成的夹角β为40°至140°。
  8. 根据权利要求1至4中任一项所述的二次电池，其中，所述条纹凸部包括有机材料和导电材料，所述有机材料包括聚丙烯腈、聚乙二醇、丁苯橡胶、尼龙、水性聚酰胺树脂、二甲基硅橡胶、聚丙烯酸、聚甲基丙烯酸甲酯或聚偏二氟乙烯中的至少一种，所述导电材料包括石墨、导电纤维中的至少一种，所述有机材料和所述导电材料的质量比为(4至49):1。
  9. 根据权利要求1至4中任一项所述的二次电池，其中，所述正极集流体的厚度h3为8μm至10μm。
  10. 根据权利要求1至4中任一项所述的二次电池，其中，所述正极材料层的压实密度PD大于或等于4.24g/cm3。
  11. 根据权利要求1至4中任一项所述的二次电池，其满足以下特征中的至少一者：
    (1)所述正极材料层的涂布面密度为240mg/1540.25mm2至400mg/1540.25mm2；
    (2)所述正极极片的单位抗断裂力强度为150MPa至270MPa；
    (3)所述正极材料层的厚度h2为36μm至61μm。
  12. 一种电子装置，其包含权利要求1至11中任一项所述的二次电池。
PCT/CN2025/084689 2024-03-31 2025-03-25 一种二次电池和电子装置 Pending WO2025209249A1 (zh)

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Publication number Priority date Publication date Assignee Title
JP2012049089A (ja) * 2010-08-30 2012-03-08 Hitachi Maxell Energy Ltd 非水電解質二次電池
CN117638254A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 一种电极组件及电池
CN117637990A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 极片、电极组件及电池
CN117637991A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 一种极片、电极组件及电池
CN118281293A (zh) * 2024-03-31 2024-07-02 宁德新能源科技有限公司 一种二次电池和电子装置

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JP2012049089A (ja) * 2010-08-30 2012-03-08 Hitachi Maxell Energy Ltd 非水電解質二次電池
CN117638254A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 一种电极组件及电池
CN117637990A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 极片、电极组件及电池
CN117637991A (zh) * 2024-01-26 2024-03-01 宁德新能源科技有限公司 一种极片、电极组件及电池
CN118281293A (zh) * 2024-03-31 2024-07-02 宁德新能源科技有限公司 一种二次电池和电子装置

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