WO2022204984A1 - 电化学装置及用电设备 - Google Patents

电化学装置及用电设备 Download PDF

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WO2022204984A1
WO2022204984A1 PCT/CN2021/084098 CN2021084098W WO2022204984A1 WO 2022204984 A1 WO2022204984 A1 WO 2022204984A1 CN 2021084098 W CN2021084098 W CN 2021084098W WO 2022204984 A1 WO2022204984 A1 WO 2022204984A1
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electrode sheet
lithium
oxide
negative electrode
thickness
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PCT/CN2021/084098
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English (en)
French (fr)
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魏红梅
张楠
岳影影
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宁德新能源科技有限公司
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Priority to PCT/CN2021/084098 priority Critical patent/WO2022204984A1/zh
Priority to CN202180006137.6A priority patent/CN114730962A/zh
Publication of WO2022204984A1 publication Critical patent/WO2022204984A1/zh

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    • 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
    • H01M50/463—Separators, membranes or diaphragms characterised by their shape
    • 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
    • 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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • 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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/44—Fibrous material

Definitions

  • the present application relates to the field of battery technology, in particular to an electrochemical device and electrical equipment.
  • Electrochemical devices eg, lithium-ion batteries
  • the width of the negative electrode sheet is larger than the width of the positive electrode sheet.
  • the area of the negative electrode sheet beyond the positive electrode sheet produces an overhang, also known as A/C overhang.
  • A/C overhang also known as A/C overhang.
  • the capacity of the positive electrode is smaller than that of the negative electrode, so as to improve the reliability of the battery and avoid too much lithium ions released from the positive electrode during the charging process, which cannot be completely inserted into the negative electrode active material. Lithium precipitation occurs on the surface of the sheet, which brings safety risks.
  • a first aspect of the present application provides an electrochemical device including a positive electrode sheet, a negative electrode sheet and a separator.
  • the negative electrode sheet includes a first extension area, and the first extension area is along the width direction of the negative electrode sheet, and the negative electrode sheet extends beyond the positive electrode sheet.
  • the isolation layer includes a first area located between the positive electrode sheet and the negative electrode sheet, and a second area located on the surface of the first protruding area, and the thickness of the second area is greater than that of the first area.
  • the thickness of the first region is H1
  • the thickness of the second region is H2
  • the thickness of the positive electrode sheet is Hc, 1/4 ⁇ (H2-H1)/Hc ⁇ 5/4.
  • the isolation layer further includes a second protruding region, the second protruding region is along the width direction of the negative electrode sheet, the isolation layer is beyond the region of the negative electrode sheet, and the thickness of the second protruding region is greater than the thickness of the second region.
  • the thickness of the second extension region is H3, the thickness of the second region is H2, and the thickness of the negative electrode sheet is HA , 1/4 ⁇ (H3-H2)/ HA ⁇ 5 /4.
  • the adhesive force between the first region and the negative electrode sheet is F1
  • the adhesive force between the second region and the negative electrode sheet is F2, satisfying: 1 ⁇ F2/F1 ⁇ 5.
  • the isolation layer includes polymer fibers, and optionally further includes particles including at least one of inorganic oxides, lithium ion conductive inorganics, and organics.
  • the polymer fibers comprise at least one of the following: polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyethylene oxide, polyphenylene oxide, polypropylene carbonate ester, polymethyl methacrylate, polyethylene terephthalate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-chlorotrifluoroethylene) and derivatives thereof.
  • the inorganic oxide includes at least one of the following: hafnium oxide, strontium titanate, tin dioxide, cesium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium oxide, yttrium oxide, Alumina, titania, silica, hydrated alumina, magnesium hydroxide, aluminum hydroxide.
  • the lithium ion conductive inorganic includes at least one of the following: lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanate, lithium germanium thiophosphate, lithium nitride, SiS 2 Glass, P 2 S 5 glass, lithium oxide, lithium fluoride, lithium hydroxide, lithium carbonate, lithium metaaluminate, lithium germanium phosphorus sulfur ceramics, garnet ceramics.
  • the organic material includes at least one of the following: polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyethylene oxide, polyphenylene oxide, polypropylene carbonate, Polymethyl methacrylate, polyethylene terephthalate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-chlorotrifluoroethylene) and derivatives thereof.
  • a second aspect of the present application provides an electrical device, comprising any of the above electrochemical devices.
  • the thickness of the isolation layer in the second region is greater than the thickness of the first region, and the isolation layer in the second region is used to make up for the part of the positive electrode sheet that is not disposed on the surface of the first protruding region , thereby reducing the thickness difference between the overhang region and the non-overhang region of the electrode assembly, which is beneficial to avoid lithium precipitation on the overhang surface and ensure battery performance.
  • 1 to 10 are schematic diagrams of the cooperation of ten kinds of pole pieces and isolation layers of the electrochemical device of the present application;
  • FIG. 11 is a schematic flowchart of a method for preparing an isolation layer according to an embodiment of the present application.
  • FIG. 12 is a schematic view of the microstructure of the isolation layer according to an embodiment of the application.
  • FIG. 13 is a schematic view of the microstructure of the isolation layer according to another embodiment of the present application.
  • an embodiment of the present application provides an electrochemical device that utilizes the thickness difference of the isolation layer to compensate for the thickness difference between the electrode assembly in the overhang area and the non-overhang area, that is, the thickness of the isolation layer in the overhang area is large, and the thickness of the isolation layer in the non-overhang area is large. The thickness is small, so as to ensure the charge and discharge performance of the electrochemical device.
  • the electrochemical devices of the embodiments of the present application include, but are not limited to, all kinds of primary batteries, secondary batteries, fuel cells, solar cells, and capacitor (eg, supercapacitor) batteries.
  • the electrochemical device may preferably be a lithium ion battery, including but not limited to lithium metal secondary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, and lithium ion polymer secondary batteries.
  • the electrochemical devices of the embodiments of the present application may exist in the form of batteries, battery cells, battery modules, or battery modules.
  • the electrochemical device includes a positive electrode sheet 11 , a negative electrode sheet 12 and a separator 13 .
  • the isolation layer 13 is arranged between the positive electrode sheet 11 and the negative electrode sheet 12 to separate the positive electrode sheet 11 and the negative electrode sheet 12 so that the electrons in the electrochemical device cannot pass freely, and the ions in the electrolyte can pass freely.
  • the positive electrode sheet 11, the negative electrode sheet 12 and the separator 13 are wound or stacked to form an electrode assembly of an electrochemical device. It should be understood that the number of positive electrode sheets, negative electrode sheets and isolation layers is not limited in the embodiments of the present application.
  • One of the isolation layers 13 is taken as an example for description herein, and the electrochemical device also includes other isolation layers 14 .
  • the positive electrode sheet 11 includes a positive electrode current collector 111 and a positive electrode active material layer 112 formed on both surfaces of the positive electrode current collector 111, the positive electrode active material layer 112 containing a positive electrode active material.
  • the material of the positive electrode current collector 111 is not particularly limited, and may be any material suitable for use as a positive electrode current collector.
  • the positive electrode current collector 111 includes, but is not limited to, metal materials such as aluminum (Al), stainless steel, nickel (Ni) plating, titanium (Ti), and tantalum (Ta); carbon materials such as carbon cloth and carbon paper.
  • the cathode active material layer 112 may be one or more layers, each layer of the multiple layers of cathode active material containing the same or a different cathode active material.
  • the positive electrode active material is a material capable of reversibly intercalating and deintercalating metal ions such as lithium ions.
  • the chargeable capacity of the positive electrode active material layer 112 is smaller than the discharge capacity of the negative electrode active material layer 122 to prevent lithium metal from precipitating on the negative electrode sheet 12 during charging.
  • the positive electrode active material can be a material containing lithium and at least one transition metal.
  • positive active materials may include, but are not limited to, lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds, transition metals including but not limited to vanadium (V), titanium, chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel, copper (Cu), and the like.
  • a substance having a different composition may be attached to the surface of the positive electrode active material layer 112 .
  • the attached substances include but are not limited to: oxides such as alumina, silica, titania, zirconia, magnesia, calcium oxide, boron oxide, antimony oxide, bismuth oxide; lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, Sulfates such as calcium sulfate, aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, magnesium carbonate; carbon, etc.
  • the method of attaching the substance to the surface of the positive active material includes, but is not limited to: dissolving or suspending the attached substance in a solvent and infiltrating and adding it to the positive active material and drying; A method of reacting by heating or the like after being added to the positive electrode active material, a method of adding to a positive electrode active material precursor while firing, and the like.
  • a method of mechanical attachment can be performed using a carbon material (eg, activated carbon, etc.).
  • Adhering the substance on the surface of the positive electrode active material can suppress the oxidation reaction of the electrolyte on the surface of the positive electrode active material, which is beneficial to improve the life of the electrochemical device.
  • the positive electrode active material and the adhered material on the surface thereof may also be referred to as the positive electrode active material layer 112 .
  • the negative electrode sheet 12 includes a negative electrode current collector 121 and negative electrode active material layers 122 formed on both surfaces of the negative electrode current collector 121, the negative electrode active material layers 122 containing the negative electrode active material.
  • the negative electrode current collector 121 includes, but is not limited to, metal foil, metal film, metal mesh, stamped metal plate, foamed metal plate, etc.; conductive resin plate.
  • the anode active material layer 122 may be one or more layers, and each layer of the multiple layers of anode active material may contain the same or a different anode active material.
  • the negative electrode active material is any material that can reversibly intercalate and deintercalate metal ions such as lithium ions.
  • the negative electrode active material includes, but is not limited to: graphite, hard carbon, soft carbon, carbon materials such as secondary carbon microbeads (MCMB), silicon (Si), represented by SiOx (0 ⁇ x ⁇ 2) Silicon-containing compounds such as silicon oxides, metallic lithium, metals that form alloys with lithium and alloys thereof, amorphous compounds mainly composed of oxides such as tin dioxide, and lithium titanate.
  • the negative electrode sheet 12 includes a first extension area 12a, and the first extension area 12a is along the width direction of the negative electrode sheet 12 (ie, along the direction indicated by the arrow x in FIG. 1 ), and the negative electrode sheet 12 extends beyond the positive electrode
  • the separator 13 is a separator disposed between the positive electrode sheet 11 and the negative electrode sheet 12 . As shown in FIG. 1 , the separator 13 can be provided between the positive electrode active material layer 112 and the negative electrode active material layer 122 .
  • One of the main functions of the isolation layer 13 is to isolate the positive electrode sheet 11 and the negative electrode sheet 12, so that electrons cannot freely pass through, and ions in the electrolyte solution are allowed to pass freely.
  • the isolation layer 13 includes: a first region 13a located between the positive electrode sheet 11 and the negative electrode sheet 12, and a second region 13b located on the surface of the first protruding region 12a.
  • the thickness H2 of the second region 13b is greater than the thickness H1 of the first region 13a, that is, H2>H1. Thickness
  • the thickness of the first region 13a and the thickness of the second region 13b can be measured, respectively, using a test method commonly used in the art, for example, taking pictures at the cross-section through a scanning electron microscope (SEM).
  • the second region 13b can make up for the portion of the positive electrode sheet 11 that is not provided on the surface of the first extension region (ie A/C overhang) 12a, thereby reducing the size of the electrochemical device in the A/C overhang region and the non-A/C overhang region
  • the thickness difference of which is beneficial to avoid the phenomenon of lithium precipitation on the A/C overhang, and ensure the charge-discharge performance of the electrochemical device.
  • the so-called thickness difference represents the difference between the sum of the thicknesses of the structural layers in the A/C overhang region and the non-A/C overhang region.
  • the thickness H2 of the second region 13b can just make up for the part of the positive electrode sheet 11 that is not disposed on the surface of the first protruding region 12a, that is, the electrochemical device is at A/
  • the thickness H2 of the second region 13b may also be larger or smaller than the thickness in the example shown in FIG. 4 within a certain threshold. If the thickness H2 of the second region 13b is too large or too small, it will cause the difference in thickness between the A/C overhang region and the non-A/C overhang region. For example, if H2 is too large, the thickness of the non-A/C overhang region will be smaller than A/C overhang region. The thickness of the C overhang region; and if H2 is too small, the difference in thickness between the A/C overhang region and the non-A/C overhang region will still lead to lithium precipitation in the A/C overhang region.
  • the first The thickness H1 of the region 13a, the thickness H2 of the second region 13b, and the thickness Hc of the positive electrode sheet 11 may satisfy the relationship: 1/4 ⁇ (H2-H1)/Hc ⁇ 5/4.
  • the minimum thickness of the isolation layer 13 (ie, the thickness H1 of the first region 13a ) is within the above range, which can ensure insulation and structural strength, and ensure the rate characteristic and energy density of the electrochemical device.
  • the isolation layer 13 further includes a second protruding area 13c, and the second protruding area 13c is along the width direction of the negative electrode sheet 12 (ie, along the direction indicated by the arrow x in FIG. 1 ), The region where the isolation layer 13 extends beyond the negative electrode sheet 12 is also called S/A overhang.
  • the thickness H3 of the second protruding region 13c is greater than the thickness H2 of the second region 13b, H3>H2.
  • the second overhang area 13c can make up for the part of the negative electrode sheet 12 that is not provided on the surface of the second overhang area (ie S/A overhang) 13c, and can reduce the size of the electrochemical device in the S/A overhang area and the non-S/A overhang area
  • the difference in thickness of the structural layer is beneficial to ensure the performance of the electrochemical device.
  • the thickness H3 of the second extension region 13c may also be greater or less than the thickness in the example shown in FIG. 9 within a certain threshold.
  • H3, H2, and HA may satisfy the following: 1/4 ⁇ (H3-H2)/ HA ⁇ 5 /4.
  • the adhesive force between the isolation layer 13 and the negative electrode sheet 12 satisfies the preset requirements, which can prevent the isolation layer 13 from shrinking at high temperature, or the isolation layer 13 is turned inward at the edge due to the impact of the electrolyte when it is dropped, so as to ensure the positive electrode
  • the tab 11 and the negative tab 12 are isolated to prevent short circuits.
  • the adhesive force between the first region 13a and the negative electrode sheet 12 is F1
  • the adhesive force between the second region 13b and the negative electrode sheet 12 is F2, satisfying: 1 ⁇ F2/F1 ⁇ 5. In some scenarios, 5N/m ⁇ F2 ⁇ 25N/m.
  • the porosity of the isolation layer 13 is ⁇ and the pore size is ⁇ , satisfying at least one of the following conditions:
  • the embodiments of the present application further provide a method for preparing the isolation layer 13 .
  • the following describes the preparation method of the isolation layer 13 by taking the material of the isolation layer 13 as at least polymer fibers as an example.
  • a preparation method according to an embodiment of the present application includes steps S11 and S12.
  • the preparation process and materials of the positive electrode sheet 11 and the negative electrode sheet 12 are not limited in the embodiments of the present application.
  • the negative electrode active material graphite (Graphite), conductive carbon black (Super P), and styrene-butadiene rubber (SBR) can be mixed in a weight ratio of 96:1.5:2.5, and deionized water is added as a solvent to prepare a solid
  • deionized water is added as a solvent to prepare a solid
  • the slurry with a content of 0.7 is mixed evenly, then the slurry is evenly coated on one surface of the negative electrode current collector (eg copper foil) 121, and dried at 110° C. to obtain a negative electrode active material layer 122, and then Another negative electrode active material layer 122 is formed on the other surface of the negative electrode current collector 122 using the same process.
  • the negative electrode sheet 12 is obtained by cutting the pieces and welding the tabs.
  • the positive active material lithium cobalt oxide (LiCoO 2 ), conductive carbon black, and polyvinylidene fluoride (PVDF) are mixed in a weight ratio of 97.5:1.0:1.5, and N-methylpyrrolidone (NMP) is added as a solvent.
  • NMP N-methylpyrrolidone
  • the slurry with a content of 0.75 is uniformly stirred, and then the slurry is uniformly coated on the positive electrode current collector (eg, aluminum foil) 111 and dried at 90° C. to obtain a positive electrode active material layer 112 .
  • another positive electrode active material layer 112 is formed on the other surface of the positive electrode current collector 111 using the same process. Further, the positive electrode sheet 11 is obtained by cutting pieces and welding tabs.
  • the embodiments of the present application also do not limit the types of polymers, in some scenarios, including but not limited to at least one of the following: polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyethylene Ethylene oxide, polyphenylene ether, polypropylene carbonate, polymethyl methacrylate, polyethylene terephthalate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-trifluoride Chlorofluoroethylene) and its derivatives.
  • polyvinylidene fluoride polyimide
  • polyamide polyacrylonitrile
  • polyethylene glycol polyethylene Ethylene oxide
  • polyphenylene ether polypropylene carbonate
  • polymethyl methacrylate polyethylene terephthalate
  • the isolation layer 13 may be formed by a polymer. As shown in FIG. 12 , the isolation layer 13 is a polymer fiber layer, and has a pore size and a porosity that satisfy the passage of reactive ions such as lithium ions.
  • the pore size and porosity of the structural layer formed by the polymer, that is, the polymer fiber layer, may be too large.
  • the isolation layer 13 may also be provided with particles, as shown in FIG. meet the reservation requirements.
  • the particles can be disposed within a layer of polymer fibers.
  • the particles may be provided on a layer of polymer fibers, ie, the isolation layer 13 comprises a two-layer structure, the first layer being a layer of polymer fibers and the second layer being a layer of particles.
  • the particle layer (ie, the second layer) has a porosity of ⁇ 0, a pore diameter of ⁇ 0, a thickness of H0, a resistivity of ⁇ , and an ionic conductivity of ⁇ , which satisfies at least one of the following conditions:
  • the porosity ⁇ 0, the pore diameter ⁇ 0, and the thickness H0 of the particle layer (ie, the second layer) are within the above ranges, which can help ensure the free passage of reactive ions such as lithium ions in the electrolyte.
  • the material of the particles includes at least one of inorganic oxides, lithium-ion conductive inorganics, and organics.
  • Inorganic oxides include at least one of the following: hafnium oxide, strontium titanate, tin dioxide, cesium oxide, magnesium oxide, nickel oxide, calcium oxide, barium oxide, zinc oxide, zirconium oxide, yttrium oxide, aluminum oxide, titanium oxide, Silica, hydrated alumina, magnesium hydroxide, aluminum hydroxide.
  • Lithium ion conductive inorganic substances include at least one of the following: lithium phosphate, lithium titanium phosphate, lithium aluminum titanium phosphate, lithium lanthanum titanate, lithium germanium thiophosphate, lithium nitride, SiS 2 glass, P 2 S 5 Glass, lithium oxide, lithium fluoride, lithium hydroxide, lithium carbonate, lithium metaaluminate, lithium germanium phosphorus sulfur ceramics, garnet ceramics.
  • the organic matter includes at least one of the following: polyvinylidene fluoride, polyimide, polyamide, polyacrylonitrile, polyethylene glycol, polyethylene oxide, polyphenylene ether, polypropylene carbonate, polymethyl methacrylate , Polyethylene terephthalate, poly(vinylidene fluoride-hexafluoropropylene), poly(vinylidene fluoride-chlorotrifluoroethylene) and derivatives thereof.
  • the isolation layer 13 may be formed on one or both surfaces of the positive electrode sheet 11 , and may also be formed on one or both surfaces of the negative electrode sheet 12 , which is not limited in the embodiment of the present application.
  • Yet another embodiment of the present application provides an electrical device, including a load and the electrochemical device of any of the foregoing embodiments, where the electrochemical device is used to supply power to the load.
  • Electrical equipment can be implemented in various specific forms, such as drones, electric vehicles, electric cleaning tools, energy storage products, electric vehicles, electric bicycles, electric navigation tools and other electronic products.
  • the electrical equipment specifically includes but is not limited to: notebook computers, pen input computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, headsets, VCRs, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notepads, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, assisted bicycles, bicycles, Lighting equipment, toys, game consoles, clocks, power tools, flashlights, cameras, large-scale household storage batteries and lithium-ion capacitors, etc.
  • the electrical equipment has the electrochemical device of any of the foregoing embodiments, the electrical equipment can produce the beneficial effects of the electrochemical device of the corresponding embodiment.
  • an element defined by the phrase "comprises a" does not preclude the presence of additional identical elements in a process, method, article, or device that includes the element, and further, in different embodiments Components, features and elements with the same name may have the same meaning or may have different meanings, and their specific meanings need to be determined by their explanations in this specific embodiment or further combined with the context in this specific embodiment.
  • isolation layer Disperse 95% polyvinylidene fluoride, 4.5% acrylonitrile and 0.5% boron trifluoride in a solvent with a weight ratio of dimethylformamide and acetone of 7:3, and stir Homogenize until the viscosity of the slurry is stable to obtain a solution A with a mass fraction of 25%.
  • a polymer fiber layer with H1 of 10 ⁇ m and H2 of 35 ⁇ m was prepared by electrospinning process using solution A as a raw material. After that, a polymer fiber layer was also prepared on the other surface of the negative electrode sheet by the same process. Next, the solvent was removed by vacuum drying at 40°C, and then the temperature was raised to 80°C for 6 h to complete the cross-linking process, and a negative electrode sheet with isolation layers on both sides was obtained.
  • ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC) were first mixed in a mass ratio of 30:50:20, and then the lithium salt lithium hexafluorophosphate (LiPF) was added. 6 ) Dissolving and mixing uniformly to obtain an electrolyte solution with a LiPF 6 concentration of 1.15 mol/L.
  • Example 2 The difference from Example 1 is that H2 is controlled to be 60 ⁇ m.
  • Example 3 The difference from Example 1 is that H2 is controlled to be 85 ⁇ m.
  • Example 4 The difference from Example 1 is that H2 is controlled to be 110 ⁇ m.
  • Example 5 The difference from Example 1 is that H2 is controlled to be 135 ⁇ m.
  • Example 6 The difference from Example 3 is that while electrospinning with solution A, alumina ceramics were deposited by an air spinning process.
  • the spinning solution used in the first area on the surface of the negative electrode sheet is a mixture of 95% polyvinylidene fluoride, 3.8% acrylonitrile, 0.5% boron trifluoride, and 0.7% styrene butadiene rubber. Disperse in a solvent with a weight ratio of dimethylformamide and acetone of 7:3, and stir uniformly until the viscosity of the slurry is stable to obtain a solution with a mass fraction of 25%.
  • the spinning solution used in the second area on the surface of the negative electrode sheet is 95% polyvinylidene fluoride, 4.3% acrylonitrile, 0.5% boron trifluoride, 0.2% styrene-butadiene rubber dispersed in dimethylformamide and In a solvent with an acetone weight ratio of 7:3, and stirring uniformly until the viscosity of the slurry is stable, a solution with a mass fraction of 25% is obtained.
  • the spinning solution used in the first area on the surface of the negative electrode is a mixture of 95% polyvinylidene fluoride, 3.2% acrylonitrile, 0.5% boron trifluoride, and 1.3% styrene butadiene rubber. Disperse in a solvent with a weight ratio of dimethylformamide and acetone of 7:3, and stir uniformly until the viscosity of the slurry is stable to obtain a solution with a mass fraction of 25%.
  • the spinning solution used in the second area on the surface of the negative electrode sheet is 95% polyvinylidene fluoride, 4.3% acrylonitrile, 0.5% boron trifluoride, 0.2% styrene-butadiene rubber dispersed in dimethylformamide and In a solvent with an acetone weight ratio of 7:3, and stirring uniformly until the viscosity of the slurry is stable, a solution with a mass fraction of 25% is obtained.
  • Example 9 The difference from Example 7 is that H3 is controlled to be 115 ⁇ m.
  • Example 10 The difference from Example 7 is that H3 is controlled to be 145 ⁇ m.
  • Example 11 The difference from Example 7 is that H3 is controlled to be 175 ⁇ m.
  • Example 12 The difference from Example 7 is that H3 is controlled to be 205 ⁇ m.
  • Example 13 The difference from Example 7 is that H3 is controlled to be 245 ⁇ m.
  • Comparative Example 1 The difference from Example 1 is that conventional polyethylene is used as the separator.
  • Lithium deposition test The prepared lithium-ion battery was charged at a high rate at 1C rate, charged to 100% SOC, and the battery was disassembled to observe the surface of the negative electrode sheet.
  • the gray metal layer in more than 10% of the area was defined as severe lithium deposition, 5-
  • the presence of gray metal layer in 10% area is defined as slight lithium deposition, and the presence or absence of gray metal layer below 5% area is defined as no lithium deposition.
  • Thickness expansion rate and cycle capacity retention rate test at 25°C, use a micrometer to measure the initial thickness H 0 of the lithium-ion battery, charge the lithium-ion battery to 4.45V at a constant current of 0.5C, and then charge it to a current at a constant voltage of 4.45V It is 0.05C, and then discharge to 3.0V with a constant current of 0.5C to obtain the discharge capacity, which is the first discharge capacity.
  • the above steps were repeated 100 times, the discharge capacity at the 100th time was recorded, and the thickness H 1 of the lithium-ion battery after the 100th cycle was measured with a micrometer.
  • Capacity retention rate at 100 cycles 100th discharge capacity/first discharge capacity.
  • Drop test Take 10 lithium-ion batteries for drop test, and record the number of lithium-ion batteries that pass the test.
  • Drop test pass rate number of lithium-ion batteries that passed the test/10.
  • the electrochemical device of the embodiment of the present application has the following characteristics: the phenomenon of lithium precipitation can be significantly improved, the expansion rate after multiple cycles of charge and discharge is low, and the safety when falling High, the capacity loss after multiple cycles of charge and discharge is small.
  • the thickness H2 of the separator 13 on the A/C overhang satisfies 1/2 ⁇ (H2-H1)/Hc ⁇ 1, and the adhesive force between the separator 13 and the negative electrode sheet 12 satisfies F2/F1 ⁇ 1.5, or at S
  • the thickness H3 on the /A overhang further satisfies 1/2 ⁇ (H3-H2)/ H A ⁇ 1, the electrochemical device can have relatively good performance.

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Abstract

本申请公开一种电化学装置及用电设备。电化学装置包括正极片、负极片和隔离层，负极片包括第一伸出区，即A/C overhang；隔离层包括位于正极片与负极片之间的第一区域，及位于第一伸出区表面的第二区域，第二区域的厚度大于第一区域的厚度。本申请利用第二区域的隔离层弥补正极片未设于第一伸出区上的部分，缩小电极组件在A/C overhang区域和非A/C overhang区域的厚度差异，有利于避免A/C overhang上出现析锂现象，保证电池性能。

Description

电化学装置及用电设备 技术领域
本申请涉及电池技术领域，具体涉及一种电化学装置及用电设备。
背景技术
电化学装置(例如，锂离子电池)具有电压高、体积小、质量轻、比容量高、无记忆效应、无污染、自放电小和循环寿命长等优点，已广泛应用于众多领域。随着电化学装置的广泛应用，其性能也受到越来越多的关注。
在目前的电化学装置中，负极片的宽度大于正极片的宽度，沿负极片的宽度方向，负极片超出正极片的区域产生伸出区(overhang)，又称A/C overhang，研究人员认为，电池设计中增加overhang区域可调节正负极容量，一般正极容量小于负极容量，以提升电池可靠性，避免充电过程中正极脱出的锂离子过多，无法完全插入负极活性材料中，从而在负极片表面出现析锂，带来安全风险。但是，电极组件在overhang区域和其他区域(非overhang区域)存在厚度差异(结构层的厚度之和不同)，在热压化成过程中，电极组件受到的压力不均匀，导致电池界面恶化，充电时容易在overhang表面出现析锂现象，影响充放电性能。
发明内容
本申请第一方面提供一种电化学装置，包括正极片、负极片和隔离层。负极片包括第一伸出区，第一伸出区为沿负极片的宽度方向，负极片超出正极片的区域。隔离层包括位于正极片与负极片之间的第一区域，以及位于第一伸出区表面的第二区域，第二区域的厚度大于第一区域的厚度。
在一些实施方式中，第一区域的厚度为H1，第二区域的厚度为H2，正极片的厚度为Hc，1/4≤(H2-H1)/Hc≤5/4。
在一些实施方式中，5μm≤H1≤30μm。
在一些实施方式中，35μm≤H2≤230μm。
在一些实施方式中，30μm≤Hc≤200μm。
在一些实施方式中，隔离层还包括第二伸出区，第二伸出区为沿负极片的宽度方向，隔离层超出负极片的区域，第二伸出区的厚度大于第二区域的厚度。
在一些实施方式中，第二伸出区的厚度为H3，第二区域的厚度为H2，负极片的厚度为H A，1/4≤(H3-H2)/H A≤5/4。
在一些实施方式中，25μm≤H A≤200μm。
在一些实施方式中，第一区域与负极片之间的粘接力为F1，第二区域与负极片之间的粘接力为F2，满足：1≤F2/F1≤5。
在一些实施方式中，5N/m≤F2≤25N/m。
在一些实施方式中，隔离层包括聚合物纤维，以及可选地进一步包括颗粒，颗粒包括无机氧化物、锂离子传导性无机物以及有机物中的至少一种。
在一些实施方式中，聚合物纤维包括以下至少一种：聚偏二氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯，聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-三氟氯乙烯)及其衍生物。
在一些实施方式中，无机氧化物包括以下至少一种：氧化铪、钛酸锶、二氧化锡、氧化铯、氧化镁、氧化镍、氧化钙、氧化钡、氧化锌、氧化锆、氧化钇、氧化铝、氧化钛、二氧化硅、水合氧化铝、氢氧化镁、氢氧化铝。
在一些实施方式中，锂离子传导性无机物包括以下至少一种：磷酸锂、锂钛磷酸盐、锂铝钛磷酸、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、氧化锂、氟化锂、氢氧化锂、碳酸锂、偏铝酸锂、锂锗磷硫陶瓷、石榴石陶瓷。
在一些实施方式中，有机物包括以下至少一种：聚偏二氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯，聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-三氟氯乙烯)及其衍生物。
本申请第二方面提供一种用电设备，包括上述任一项电化学装置。
在本申请的电化学装置及用电设备中，隔离层在第二区域的厚度大于第一区域的厚度，利用第二区域的隔离层弥补正极片未设置于第一伸出区表面上的部分，从而缩小电极组件在overhang区域和非overhang区域的厚度差异，有利于避免在overhang表面出现析锂现象，保证电池性能。
附图说明
图1至图10是本申请的电化学装置的十种极片与隔离层的配合示意图；
图11是本申请一实施例的隔离层的制备方法的流程示意图；
图12为本申请一实施例的隔离层的微观结构示意图；
图13为本申请另一实施例的隔离层的微观结构示意图。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合各个实施例及各个实施例的附图，对本申请技术方案进行清楚、完整地描述。显然，所描述实施例仅是一部分实施例，而非全部。基于本申请中的实施例，在不冲突的情况下，下述各个实施例及其技术特征可以相互组合。
应理解，在本申请实施例的描述中，术语“中心”、“纵向”、“横向”、“长度”、“宽度”、“厚度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”、“内”、“外”、“顺时针”、“逆时针”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请相应实施例的技术方案和简化描述，而非指示或暗示装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请的限制。
考虑到现有的电化学装置中，负极片超出正极片的区域产生overhang，使得电极组件在overhang区域和非overhang区域存在厚度差异，从而导致在overhang区域出现析锂现象的几率较高，影响充放电性能。针对于此，本申请实施例提供一种电化学装置，利用隔离层的厚度差异来弥补电极组件在overhang区域和非overhang区域的厚度差异，即隔离层在overhang区域的厚度大、在非overhang区域的厚度小，以此保证电化学装置的充放电性能。
在具体场景中，本申请实施例的电化学装置包括但不限于所有种类的原电池、二次电池、燃料电池、太阳能电池和电容器(例如超级电容器)电池。电化学装置可优选为锂离子电池，包括但不限于锂金属二次电池、锂离子二次电池、锂聚合物二次电池和锂离子聚合物二次电池。本申请实施例的电化学装置可以以电池、电池单元、电池模块或者电池模组的形式存在。
请参阅图1，电化学装置包括正极片11、负极片12和隔离层13。隔离层13设于正极片11和负极片12之间，用于隔离正极片11和负极片12并使电化学装置内的电子不能自由穿过，而让电解液中的离子自由通过。正极片11、负极片12和隔离层13卷绕或堆叠形成电化学装置的电极组件。应理解，正极片、负极片和隔离层的数量，本申请实施例不予以限制，本文选取其中一个隔离层13为例进行描述，电化学装置还包括其他隔离层14。
正极片11
正极片11包括正极集流体111和形成于正极集流体111的两个表面上的正极活性物质层112，该正极活性物质层112包含正极活性物质。
正极集流体111的材质没有特别限制，可以为任何适于用作正极集流体的材质。在一些实例中，正极集流体111包括但不限于：铝(Al)、不锈钢、镍(Ni)镀层、钛(Ti)、钽(Ta)等金属材料；碳布、碳纸等碳材料。
在一些实现中，正极活性物质层112可以是一层或多层，多层正极活性物质中的每层包含相同或不同的正极活性物质。正极活性物质为能够可逆地嵌入和脱嵌锂离子等金属离子的物质。优选地，正极活性物质层112的可充电容量小于负极活性物质层122的放电容量，以防止充电时锂金属析出在负极片12上。
本申请实施例并不限定正极活性物质的种类，只要是能够以电化学方式吸藏和释放金属离子(例如，锂离子)即可。在一些实现中，正极活性物质可以为含有锂和至少一种过渡金属的物质。正极活性物质的实例可包括但不限于：锂过渡金属复合氧化物和含锂过渡金属磷酸化合物，过渡金属包括但不限于为钒(V)、钛、铬(Cr)、锰(Mn)、铁(Fe)、钴(Co)、镍、铜(Cu)等。
在正极活性物质层112的表面可附着与其组成不同的物质。该附着物质包 括但不限于：氧化铝、二氧化硅、二氧化钛、氧化锆、氧化镁、氧化钙、氧化硼、氧化锑、氧化铋等氧化物；硫酸锂、硫酸钠、硫酸钾、硫酸镁、硫酸钙、硫酸铝等硫酸盐；碳酸锂、碳酸钙、碳酸镁等碳酸盐；碳等。
物质附着于正极活性物质表面的方法包括但不限于：使附着物质溶解或悬浮于溶剂中而渗入添加到该正极活性物质中并进行干燥的方法；使附着物质溶解或悬浮于溶剂中，在渗入添加到该正极活性物质中后，利用加热等使其反应的方法；添加到正极活性物质前体中同时进行烧制的方法等。在附着碳的实例中，可以使用碳材料(例如活性炭等)进行机械附着的方法。
在正极活性物质表面附着物质，可抑制正极活性物质表面的电解液的氧化反应，有利于提高电化学装置的寿命。本文的描述中，可以将正极活性物质及其表面的附着物质也称为正极活性物质层112。
负极片12
负极片12包括负极集流体121和形成于负极集流体121的两个表面上的负极活性物质层122，该负极活性物质层122包含负极活性物质。
在一些实现中，负极集流体121包括但不限于为：金属箔、金属薄膜、金属网、冲压金属板、发泡金属板等；导电性树脂板。
在一些实现中，负极活性物质层122可以是一层或多层，多层负极活性物质中的每层可以包含相同或不同的负极活性物质。负极活性物质为任何能够可逆地嵌入和脱嵌锂离子等金属离子的物质。
本申请实施例不限定负极活性物质的种类，只要是能够以电化学方式吸藏和释放金属离子即可。在一些实例中，负极活性物质包括但不限于：石墨、硬质碳、软质碳、仲炭微珠(MCMB)等碳材料、硅(Si)、以SiOx(0＜x＜2)表示的硅氧化物等含硅化合物、金属锂、与锂形成合金的金属及其合金、以二氧化锡等氧化物为主体的非晶化合物和钛酸锂。
请继续参阅图1，负极片12包括第一伸出区12a，第一伸出区12a为沿负极片12的宽度方向(即沿图1中箭头x所示的方向)，负极片12超出正极片11的区域，又称为A/C overhang。
隔离层13
隔离层13是设置于正极片11和负极片12之间的一层隔膜，如图1所示，隔离层13可以设置于正极活性物质层112和负极活性物质层122之间。隔离层13的主要作用之一是：隔离正极片11和负极片12，并使电子不能自由穿过，而让电解液中的离子自由通过。
隔离层13包括：位于正极片11与负极片12之间的第一区域13a，以及位于第一伸出区12a表面的第二区域13b。第二区域13b的厚度H2大于第一区域13a的厚度H1，即H2＞H1。厚度可使用本领域常用的测试方法，例如，通过扫描电子显微镜(SEM)拍摄截面处的照片，分别测量第一区域13a和第二区域13b的厚度。于此，第二区域13b能弥补正极片11未设于第一伸出区(即A/C overhang)12a表面上的部分，缩小电化学装置在A/C overhang区域和非A/C overhang区域的厚度差异，从而有利于避免在A/C overhang上出现析锂现象，保证电化学装置的充放电性能。所谓厚度差异表示在A/C overhang区域和非A/C overhang区域的结构层厚度之和的差值。
在一些实例中，例如在图4所示的实例中，第二区域13b的厚度H2可以恰好弥补正极片11未设置于第一伸出区12a表面上的部分，即，电化学装置在A/C overhang区域和非A/C overhang区域的结构层的厚度之和完全相等，此时(H2-H1)＝Hc，Hc为正极片11的厚度。
在其他一些实例中，第二区域13b的厚度H2也可以在一定阈值内大于或小于图4所示实例中的厚度。第二区域13b的厚度H2过大或过小，均会导致A/C overhang区域和非A/C overhang区域的厚度差异，例如H2过大，会使非A/C overhang区域的厚度小于A/C overhang区域的厚度；而H2过小，A/C overhang区域和非A/C overhang区域的厚度差异仍会导致在A/C overhang区域出现析锂现象，对此，在一些实现中，第一区域13a的厚度H1、第二区域13b的厚度H2和正极片11的厚度Hc可满足关系：1/4≤(H2-H1)/Hc≤5/4。
例如，请参阅图1、图6至图10，(H2-H1)/Hc＝3/4；请参阅图2，(H2-H1)/Hc＝1/4；请参阅图3，(H2-H1)/Hc＝1/2；请参阅图4，(H2-H1)/Hc＝1；请参阅图5， (H2-H1)/Hc＝5/4。优选地，1/2≤(H2-H1)/Hc＝1。
在一些具体场景中，5μm≤H1≤30μm。
在一些具体场景中，35μm≤H2≤230μm。
在一些具体场景中，30μm≤Hc≤200μm。
隔离层13的最小厚度(即第一区域13a的厚度H1)在上述范围内，可确保绝缘性和结构强度，保证电化学装置的倍率特性和能量密度。
请参阅图1至图10所示，隔离层13还包括第二伸出区13c，第二伸出区13c为沿负极片12的宽度方向(即沿图1中箭头x所示的方向)，隔离层13超出负极片12的区域，又称为S/A overhang。
第二伸出区13c的厚度H3大于第二区域13b的厚度H2，H3＞H2。第二伸出区13c能够弥补负极片12未设于第二伸出区(即S/A overhang)13c表面上的部分，能够缩小电化学装置在S/A overhang区域和非S/A overhang区域的结构层的厚度差异，有利于保证电化学装置性能。
在一些实例中，例如在图9所示的实例中，第二伸出区13c的厚度H3可以恰好弥补正极片11未设置于第二伸出区13c表面上的部分，即，电化学装置在S/A overhang区域和非S/A overhang区域的结构层厚度之和完全相等，此时(H3-H2)＝H A，H A为负极片12的厚度。
在其他一些实现中，第二伸出区13c的厚度H3也可以在一定阈值内大于或小于图9所示实例中的厚度。在一些实现中，H3、H2和H A可满足如下：1/4≤(H3-H2)/H A≤5/4。
例如，请参阅图6，(H3-H2)/H A＝1/4；请参阅图7，(H3-H2)/H A＝1/2；请参阅图8，(H3-H2)/H A＝3/4；请参阅图10，(H3-H2)/H A＝5/4。优选地，1/2≤(H3-H2)/H A≤1。
在一些具体场景中，25μm≤H A≤200μm。
隔离层13与负极片12之间的粘接力满足预设需求，可以避免隔离层13在高温下发生收缩、或者跌落时由于电解液的冲击导致隔离层13在边缘处内翻等，确保正极片11和负极片12之间隔离以防止短路。在一些实现中，第一区域13a 与负极片12之间的粘接力为F1，第二区域13b与负极片12之间的粘接力为F2，满足：1≤F2/F1≤5。在一些场景中，5N/m≤F2≤25N/m。
为保证在电子不能自由穿过的前提下，有利于电解液中的离子自由通过，在一些实现中，隔离层13的孔隙率为α，孔径为Ф，满足以下条件的至少一者：
a)30％≤α≤95％；
b)10nm≤Ф≤5μm。
本申请实施例进一步提供有隔离层13的制备方法。下文以隔离层13的材质至少聚合物纤维为例，描述该隔离层13的制备方法。
如图11所示，为本申请一实施例的制备方法，包括步骤S11和S12。
S11：采用纺丝工艺将至少含有聚合物的溶液喷涂于正极片11或负极片12的至少一表面上，并烘干形成隔离层13。
S12：将正极片和负极片经预定处理后组装成电化学装置。
正极片11和负极片12的制备工艺及材料，本申请实施例不予以限制。
在一些实例中，可以将负极活性材料石墨(Graphite)、导电炭黑(Super P)、丁苯橡胶(SBR)按照重量比96:1.5:2.5进行混合，加入去离子水作为溶剂，调配成为固含量为0.7的浆料，并搅拌均匀，然后将浆料均匀涂覆在负极集流体(例如铜箔)121的一表面上，在110℃条件下烘干，得到一负极活性物质层122，接着采用相同工艺在负极集流体122的另一表面上形成另一负极活性物质层122。进一步地，再经过裁片和焊接极耳，得到负极片12。
将正极活性材料钴酸锂(LiCoO 2)、导电炭黑、聚偏二氟乙烯(PVDF)按照重量比97.5:1.0:1.5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0.75的浆料，并搅拌均匀，然后将浆料均匀涂覆在正极集流体(例如铝箔)111上，在90℃条件下烘干，得到一正极活性物质层112。接着采用相同工艺在正极集流体111的另一表面上形成另一正极活性物质层112。进一步地，再经过裁片和焊接极耳，得到正极片11。
本申请实施例也不限制聚合物的种类，在一些场景中，包括但不限于以下至少一种：聚偏二氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化 乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯，聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-三氟氯乙烯)及其衍生物。
本申请可以通过聚合物形成隔离层13，如图12所示，隔离层13为一聚合物纤维层，具有满足锂离子等反应离子通过的孔径和孔隙率。
聚合物形成的结构层，即聚合物纤维层的孔径和孔隙率可能过大，于此，隔离层13还可以设有颗粒，如图13所示，通过颗粒使得隔离层13的孔径和孔隙率符合预定要求。
在一些实现中，颗粒可以设于聚合物纤维层内。
在另一些实现中，颗粒可以设于聚合物纤维层上，即，隔离层13包括两层结构，第一层为聚合物纤维层，第二层为颗粒层。
颗粒层(即第二层)的孔隙率为α0，孔径为Ф0，厚度为H0，电阻率为ρ，离子电导率为σ，满足以下条件的至少一者：
a)10％≤α0≤40％；
b)0.1nm≤Ф0≤1μm；
c)0.1μm≤H0≤20μm；
d)ρ＞107Ω·m；
e)10 -2S/cm≤σ≤10 -8S/cm。
颗粒层(即第二层)的孔隙率α0、孔径Ф0、厚度H0在上述范围内，可有利于确保电解液中的锂离子等反应离子自由通过。
在一些实例中，颗粒的材质包括无机氧化物、锂离子传导性无机物以及有机物中的至少一种。
无机氧化物包括以下至少一种：氧化铪、钛酸锶、二氧化锡、氧化铯、氧化镁、氧化镍、氧化钙、氧化钡、氧化锌、氧化锆、氧化钇、氧化铝、氧化钛、二氧化硅、水合氧化铝、氢氧化镁、氢氧化铝。
锂离子传导性无机物包括以下至少一种：磷酸锂、锂钛磷酸盐、锂铝钛磷酸、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、氧化锂、氟化锂、氢氧化锂、碳酸锂、偏铝酸锂、锂锗磷硫陶瓷、石榴石陶瓷。
有机物包括以下至少一种：聚偏二氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯，聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-三氟氯乙烯)及其衍生物。
隔离层13可以形成于正极片11的一个或者两个表面上，也可以形成于负极片12的一个或者两个表面上，本申请实施例不予限制。
本申请又一实施例提供一种用电设备，包括负载以及上述任一实施例的电化学装置，该电化学装置用于为负载供电。
用电设备可以以各种具体形式来实施，例如，无人机、电动车、电动清洁工具、储能产品、电动汽车、电动自行车、电动导航工具等电子产品。在实用场景中，用电设备具体包括但不限于为：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。
本领域技术人员可理解的是，除特别用于移动目的的元件之外，根据本申请实施例的构造也能够应用于固定类型的用电设备。
由于用电设备具有前述任一实施例的电化学装置，因此，该用电设备能够产生对应实施例的电化学装置具有的有益效果。
在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括该要素的过程、方法、物品或者装置中还存在另外的相同要素，此外，不同实施例中具有同样命名的部件、特征、要素可能具有相同含义，也可能具有不同含义，其具体含义需以其在该具体实施例中的解释或者进一步结合该具体实施例中上下文进行确定。
另外，尽管本文采用术语“第一、第二、第三”等描述各种信息，但这些信息不应限于这些术语。这些术语仅用来将同一类型的信息彼此区分开。本文 中所使用的，单数形式“一”、“一个”和“该”旨在也包括复数形式。术语“或”和“和/或”被解释为包括性的，或意味着任一个或任何组合。仅当元件、功能、步骤或操作的组合在某些方式下内在地互相排斥时，才会出现该定义的例外。
以下通过具体实施例对本申请的技术方案做示例性描述：
实施例1
(1)负极片的制备：将负极活性材料石墨、导电炭黑(Super P)、丁苯橡胶(SBR)按照重量比96:1.5:2.5进行混合，加入去离子水作为溶剂，调配成为固含量为0.7的浆料，并搅拌均匀，然后将浆料均匀涂覆在负极集流体铜箔的一表面上，在110℃条件下烘干，得到一负极活性物质层，接着采用相同工艺在负极集流体的另一表面上形成另一负极活性物质层。进一步地，再经过裁片和焊接极耳，得到厚度H A为120μm的负极片。
(2)正极片的制备：将正极活性材料钴酸锂(LiCoO 2)、导电炭黑(Super P)、聚偏二氟乙烯(PVDF)按照重量比97.5:1.0:1.5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0.75的浆料，并搅拌均匀，然后将浆料均匀涂覆在正极集流体铝箔上，在90℃条件下烘干，得到一正极活性物质层。接着采用相同工艺在正极集流体的另一表面上形成另一正极活性物质层。进一步地，再经过裁片和焊接极耳，得到厚度Hc为100μm的正极片。
(3)隔离层的制备：将95％的聚偏二氟乙烯、4.5％丙烯腈和0.5％三氟化硼分散在二甲基甲酰胺与丙酮重量比为7:3的溶剂中，并搅拌均匀至浆料粘度稳定，得到质量分数为25％的溶液A。在负极片的一表面上，利用溶液A作为原料通过电纺丝工艺，制备一层H1为10μm、H2为35μm的聚合物纤维层。之后，采用相同工艺在负极片的另一表面上也制备一层聚合物纤维层。接着，在40℃条件下真空烘干去除溶剂，随后升高温度至80℃热处理6h以完成交联过程，得到双面均有隔离层的负极片。
(4)电解液的制备
在干燥氩气环境中，首先将有机溶剂碳酸乙烯酯(EC)、碳酸甲乙酯(EMC) 和碳酸二乙酯(DEC)以质量比30:50:20混合，然后加入锂盐六氟磷酸锂(LiPF 6)溶解并混合均匀，得到LiPF 6浓度为1.15mol/L的电解液。
(5)锂离子电池的制备：将前述得到的正极片和集成隔离层的负极片相对叠好并卷绕，置于外包装箔中，经注液、封装等工序后得到锂离子电池。
实施例2：与实施例1的区别在于：控制H2为60μm。
实施例3：与实施例1的区别在于：控制H2为85μm。
实施例4：与实施例1的区别在于：控制H2为110μm。
实施例5：与实施例1的区别在于：控制H2为135μm。
实施例6：与实施例3的区别在于：在利用溶液A进行电纺丝的同时，通过气纺丝工艺沉积氧化铝陶瓷。
实施例7
与实施例3的区别在于：在负极片表面的第一区域使用的纺丝溶液为将95％的聚偏二氟乙烯、3.8％丙烯腈、0.5％三氟化硼、0.7％的丁苯橡胶分散在二甲基甲酰胺与丙酮重量比为7:3的溶剂中，并搅拌均匀至浆料粘度稳定，得到质量分数为25％的溶液。在负极片表面的第二区域使用的纺丝溶液为将95％的聚偏二氟乙烯、4.3％丙烯腈、0.5％三氟化硼、0.2％的丁苯橡胶分散在二甲基甲酰胺与丙酮重量比为7:3的溶剂中，并搅拌均匀至浆料粘度稳定，得到质量分数为25％的溶液。
实施例8
与实施例3的区别在于：在负极片表面的第一区域使用的纺丝溶液为将95％的聚偏二氟乙烯、3.2％丙烯腈、0.5％三氟化硼、1.3％的丁苯橡胶分散在二甲基甲酰胺与丙酮重量比为7:3的溶剂中，并搅拌均匀至浆料粘度稳定，得到质量分 数为25％的溶液。在负极片表面的第二区域使用的纺丝溶液为将95％的聚偏二氟乙烯、4.3％丙烯腈、0.5％三氟化硼、0.2％的丁苯橡胶分散在二甲基甲酰胺与丙酮重量比为7:3的溶剂中，并搅拌均匀至浆料粘度稳定，得到质量分数为25％的溶液。
实施例9：与实施例7的区别在于：控制H3为115μm。
实施例10：与实施例7的区别在于：控制H3为145μm。
实施例11：与实施例7的区别在于：控制H3为175μm。
实施例12：与实施例7的区别在于：控制H3为205μm。
实施例13：与实施例7的区别在于：控制H3为245μm。
对比例1：与实施例1的区别在于：使用传统的聚乙烯作为隔离膜。
测试方法
析锂测试：将制得的锂离子电池在1C倍率下进行大倍率充电，充电至100％SOC拆解电池观察负极片表面，10％以上面积存在灰色金属层的定义为严重析锂，5-10％面积存在灰色金属层的定义为轻微析锂，5％面积以下存在或不存在灰色金属层的定义为不析锂。
厚度膨胀率和循环容量保持率测试：在25℃下，利用千分尺测量锂离子电池的初始厚度H 0，将锂离子电池以0.5C恒流充电至4.45V，然后以4.45V恒压充电至电流为0.05C，再以0.5C恒流放电至3.0V，得到放电容量，即为首次放电容量。将上述步骤重复100次，记录第100次的放电容量，并利用千分尺测量锂离子电池第100循环后的厚度H 1。
100次充放电后的膨胀率＝(H 1-H 0)/H 0×100％；
100次循环的容量保持率＝第100次的放电容量/首次放电容量。
跌落测试：取10支锂离子电池进行跌落测试，记录通过测试的锂离子电池数目。跌落测试通过率＝通过测试的锂离子电池数目/10。
实施例1-13与对比例1的结构参数及性能测试结果如下表所示。
Figure PCTCN2021084098-appb-000001
“/”表示不添加或不具备该特征。
结果表明，相比较于传统隔离层的电化学装置，本申请实施例的电化学装置具有如下特点：能够显著改善析锂现象，多次循环充放电后的膨胀率低，在跌落时的安全性高，多次循环充放电后的电容量损耗小。
另外，隔离层13在A/C overhang上的厚度H2满足1/2≤(H2-H1)/Hc≤1，以及与负极片12之间的粘接力满足F2/F1≥1.5，或者在S/A overhang上的厚度H3进一步满足1/2≤(H3-H2)/H A≤1时，电化学装置可具有相对较好的性能。
以上所述仅为本申请的部分实施例，并非因此限制本申请的专利范围，凡是利用本说明书及附图内容所作的等效结构变换，均同理包括在本申请的专利保护范围内。

Claims (11)

  1. 一种电化学装置，包括：
    正极片和负极片，所述负极片包括第一伸出区，所述第一伸出区为沿所述负极片的宽度方向，所述负极片超出所述正极片的区域；
    隔离层，包括位于所述正极片与所述负极片之间的第一区域，以及位于所述第一伸出区表面的第二区域，所述第二区域的厚度大于所述第一区域的厚度。
  2. 根据权利要求1所述的电化学装置，其中，所述第一区域的厚度为H1，所述第二区域的厚度为H2，所述正极片的厚度为Hc，1/4≤(H2-H1)/Hc≤5/4。
  3. 根据权利要求2所述的电化学装置，满足以下条件的至少一者：
    a)5μm≤H1≤30μm；
    b)35μm≤H2≤230μm；
    c)30μm≤Hc≤200μm。
  4. 根据权利要求1所述的电化学装置，其中，所述隔离层还包括第二伸出区，所述第二伸出区为沿所述负极片的宽度方向，所述隔离层超出所述负极片的区域，所述第二伸出区的厚度大于所述第二区域的厚度。
  5. 根据权利要求4所述的电化学装置，其中，所述第二伸出区的厚度为H3，所述第二区域的厚度为H2，所述负极片的厚度为H A，1/4≤(H3-H2)/H A≤5/4。
  6. 根据权利要求4所述的电化学装置，其中，25μm≤H A≤200μm。
  7. 根据权利要求1所述的电化学装置，其中，
    所述第一区域与所述负极片之间的粘接力为F1，所述第二区域与所述负极片之间的粘接力为F2，满足：1≤F2/F1≤5。
  8. 根据权利要求7所述的电化学装置，其中，5N/m≤F2≤25N/m。
  9. 根据权利要求1所述的电化学装置，其中，所述隔离层包括聚合物纤维，以及可选地进一步包括颗粒；所述颗粒包括无机氧化物、锂离子传导性无机物以及有机物中的至少一种。
  10. 根据权利要求9所述的电化学装置，其中，
    所述聚合物纤维包括以下至少一种：
    聚偏二氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯，聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-三氟氯乙烯)及其衍生物；
    所述无机氧化物包括以下至少一种：
    氧化铪、钛酸锶、二氧化锡、氧化铯、氧化镁、氧化镍、氧化钙、氧化钡、氧化锌、氧化锆、氧化钇、氧化铝、氧化钛、二氧化硅、水合氧化铝、氢氧化镁、氢氧化铝；
    所述锂离子传导性无机物包括以下至少一种：磷酸锂、锂钛磷酸盐、锂铝钛磷酸、锂镧钛酸盐、锂锗硫代磷酸盐、锂氮化物、SiS 2玻璃、P 2S 5玻璃、氧化锂、氟化锂、氢氧化锂、碳酸锂、偏铝酸锂、锂锗磷硫陶瓷、石榴石陶瓷；
    所述有机物包括以下至少一种：聚偏二氟乙烯、聚酰亚胺、聚酰胺、聚丙烯腈、聚乙二醇、聚氧化乙烯、聚苯醚、聚碳酸亚丙酯、聚甲基丙烯酸甲酯、聚对苯二甲酸乙二醇酯，聚(偏二氟乙烯-六氟丙烯)、聚(偏二氟乙烯-三氟氯乙烯)及其衍生物。
  11. 一种用电设备，包括根据权利要求1-10中任一项所述的电化学装置。
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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1251215A (zh) * 1997-02-28 2000-04-19 旭化成工业株式会社 无水二次电池及其制造方法
JP2019079690A (ja) * 2017-10-24 2019-05-23 株式会社豊田自動織機 蓄電モジュール
CN109860713A (zh) * 2017-11-30 2019-06-07 宁德新能源科技有限公司 电芯、电化学装置及其制造方法
JP2020053150A (ja) * 2018-09-25 2020-04-02 株式会社Ｓｏｋｅｎ 電池
CN111916670A (zh) * 2020-09-23 2020-11-10 珠海冠宇电池股份有限公司 一种负极片及其应用
CN112086620A (zh) * 2020-09-29 2020-12-15 珠海冠宇电池股份有限公司 一种负极片及其制备方法和应用

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN1251215A (zh) * 1997-02-28 2000-04-19 旭化成工业株式会社 无水二次电池及其制造方法
JP2019079690A (ja) * 2017-10-24 2019-05-23 株式会社豊田自動織機 蓄電モジュール
CN109860713A (zh) * 2017-11-30 2019-06-07 宁德新能源科技有限公司 电芯、电化学装置及其制造方法
JP2020053150A (ja) * 2018-09-25 2020-04-02 株式会社Ｓｏｋｅｎ 電池
CN111916670A (zh) * 2020-09-23 2020-11-10 珠海冠宇电池股份有限公司 一种负极片及其应用
CN112086620A (zh) * 2020-09-29 2020-12-15 珠海冠宇电池股份有限公司 一种负极片及其制备方法和应用

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