WO2025199677A1 - 一种二次电池及其制备方法、电子装置 - Google Patents

一种二次电池及其制备方法、电子装置

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Publication number
WO2025199677A1
WO2025199677A1 PCT/CN2024/083551 CN2024083551W WO2025199677A1 WO 2025199677 A1 WO2025199677 A1 WO 2025199677A1 CN 2024083551 W CN2024083551 W CN 2024083551W WO 2025199677 A1 WO2025199677 A1 WO 2025199677A1
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WO
WIPO (PCT)
Prior art keywords
negative electrode
silicon
secondary battery
current collector
carbon material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2024/083551
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English (en)
French (fr)
Other versions
WO2025199677A9 (zh
Inventor
任文臣
张丽娟
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ningde Amperex Technology Ltd
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Ningde Amperex Technology Ltd
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Priority to PCT/CN2024/083551 priority Critical patent/WO2025199677A1/zh
Publication of WO2025199677A1 publication Critical patent/WO2025199677A1/zh
Publication of WO2025199677A9 publication Critical patent/WO2025199677A9/zh
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

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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
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present application relates to the field of electrochemical technology, and in particular to a secondary battery and a preparation method thereof, and an electronic device.
  • silicon is considered the most promising lithium battery anode material to replace graphite due to its ultra-high theoretical specific capacity (Li 15 Si 4 , 3579 mAh/g) and suitable operating voltage ( ⁇ 0.5 V vs. Li/ Li + ).
  • batteries with silicon added to the anode often suffer from insufficient kinetics, resulting in reduced fast charging capability and interfacial lithium plating.
  • irregularly shaped silicon material particles have sharp edges and corners.
  • the purpose of this application is to provide a secondary battery and its preparation method, as well as an electronic device, to improve the charge rate and discharge rate of the secondary battery.
  • the specific technical solution is as follows:
  • lithium-ion batteries are used as an example of secondary batteries to explain this application, but the secondary batteries of this application are not limited to lithium-ion batteries.
  • the specific technical solutions are as follows:
  • the first aspect of the present application provides a secondary battery, which includes a positive electrode plate, a negative electrode plate, an electrolyte and a separator;
  • the negative electrode plate includes a negative electrode collector and a negative electrode material layer provided on at least one surface of the negative electrode collector, the negative electrode material layer includes a silicon-carbon material;
  • the sphericity of particles with a longest diameter greater than 10 ⁇ m in the silicon-carbon material is A, A is 0.80 to 0.98, wherein the thickness of the negative electrode collector is B ⁇ m, and the relationship between A and B is 3.14/A-0.048B ⁇ 3.7.
  • the sphericity of the silicon-carbon material matches the thickness of the negative electrode collector, the silicon-carbon material particles will not puncture the negative electrode collector, and the silicon-carbon material is improved.
  • the problem of the sharp corners of the material affecting the electron transmission channel of the negative electrode current collector is solved, thereby improving the charge rate and discharge rate of the secondary battery.
  • A is 0.84 to 0.98, which can further improve the charge rate and discharge rate of the secondary battery.
  • the negative electrode current collector has an appropriate thickness that matches the sphericity of the silicon-carbon material, thereby improving the charge rate and discharge rate of the secondary battery.
  • the tensile strength F of the negative electrode current collector is between 451 MPa and 950 MPa.
  • a tensile strength F of the negative electrode current collector within the above range indicates that the negative electrode current collector has good tensile strength.
  • the tensile strength F of the negative electrode current collector is between 470 MPa and 700 MPa.
  • the minimum angle of the cross-section profile of particles with a diameter greater than or equal to 10 ⁇ m in the silicon-carbon material is 107.8° ⁇ ⁇ ⁇ 179.2°.
  • ⁇ is within the above range, it indicates that the silicon-carbon material particles lack sharp edges and corners, making them less likely to puncture the negative electrode current collector.
  • the carbon material's sharp corners also have little impact on the electron transport channels of the negative electrode current collector, thereby facilitating improved charge and discharge rates of the secondary battery.
  • the silicon-carbon material contains silicon at a mass percentage of 40% to 54%.
  • the resulting silicon-carbon compound has a suitable specific capacity and an appropriate impedance when used in a secondary battery, thereby facilitating improved charge and discharge rates of the secondary battery, while also providing a higher energy density.
  • the temperature T3 of the carbonization treatment is 450°C to 700°C, and the time t3 is 1h to 4h;
  • the flow rate V1 of the first compound gas in the atmosphere containing the first compound is 1L/min to 4L/min, and the temperature T4 of the activation treatment is 750°C to 1000°C, and the time t4 is 6h to 20h;
  • a first aspect of the present application provides a secondary battery comprising a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator; the negative electrode sheet comprises a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector, the negative electrode material layer comprising a silicon-carbon material; the sphericity of particles with a longest diameter greater than 10 ⁇ m in the silicon-carbon material is A, A is 0.80 to 0.98, in some embodiments of the present application, A is 0.84 to 0.98, for example, the value of A can be 0.80, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98 or any two thereof.
  • the A value is too small, for example, less than 0.80, the sphericity of the silicon-carbon material is low, and the edges and corners are more, which can easily penetrate into the negative electrode current collector, causing damage to the electron transmission channel of the negative electrode current collector, thereby affecting the charge rate and discharge rate of the secondary battery.
  • the A value is too large, for example, greater than 0.98, the production cost of the silicon-carbon material is high, which increases the cost of the secondary battery.
  • the sphericity of the silicon-carbon material matches the thickness of the negative electrode current collector, the silicon-carbon material particles will not puncture the negative electrode current collector, and the problem of the silicon-carbon material edges affecting the electron transmission channel of the negative electrode current collector is improved, thereby improving the charge rate and discharge rate of the secondary battery.
  • the thickness of the negative electrode current collector is 6 ⁇ m to 20 ⁇ m
  • the tensile fracture strength F of the negative electrode current collector is 451MPa to 950MPa.
  • the tensile fracture strength F of the negative electrode current collector is 470MPa to 700MPa.
  • the tensile fracture strength F can be 451MPa, 460MPa, 470MPa, 500MPa, 600MPa, 700MPa, 800MPa, 900MPa, 950MPa, or a range consisting of any two values therebetween.
  • the tensile fracture strength F of the negative electrode current collector is within the above range, indicating that the negative electrode current collector has good tensile fracture strength.
  • negative electrode current collectors of different thicknesses and tensile fracture strengths can be purchased, and combined with the test methods of "testing the thickness B of the negative electrode current collector” and “testing the tensile fracture strength F of the negative electrode current collector” provided in this application, the negative electrode current collector with the required thickness and tensile fracture strength can be selected.
  • ⁇ is within the above range, it means that there are no sharp edges in the silicon-carbon material particles, which makes it difficult to puncture the negative electrode current collector.
  • the edges of the carbon material also have little effect on the electron transmission channel of the negative electrode current collector, which is beneficial to improving the charge rate and discharge rate of the secondary battery.
  • the minimum angle ⁇ of the cross-section profile of a silicon-carbon material particle refers to the minimum value of the angles of the corners of the outer contour formed by the cross-section of the particle.
  • the corner angle refers to the angle formed by the two tangent lines drawn along the edges of the corner.
  • Figure 1 is a schematic structural diagram of the outer contour formed by the cross-section of a silicon-carbon material particle. If ⁇ 1 is 115°, ⁇ 2 is 108°, ⁇ 3 is 142°, and ⁇ 4 is 140°, then the minimum angle ⁇ of the cross-section profile is 108°.
  • the mass percentage W1 of silicon in the silicon-carbon material is 40% to 54%.
  • the mass percentage W1 of silicon can be 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, or a range consisting of any two values therebetween.
  • the obtained silicon-carbon compound has a suitable specific capacity and has a suitable impedance when used in a secondary battery, which is beneficial to improving the charge rate and discharge rate of the secondary battery, while the secondary battery also has a higher energy density.
  • the mass percentage W3 of carbon element in the silicon-carbon material is 46% to 59%, which can further improve the charge rate and discharge rate of the secondary battery.
  • a second aspect of the present application provides a method for preparing a secondary battery according to any of the aforementioned embodiments, comprising the following steps: preparing a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte, and assembling them to obtain a secondary battery;
  • the method for preparing the silicon-carbon material in the negative electrode plate comprises the following steps:
  • the molar ratio X of the phenolic compound, formaldehyde, and ammonia is 1: (1.5 to 2.5): (0.006 to 0.012), and the phenolic compound includes at least one of phenol, cresol, nonylphenol, aryl alkylphenol, cardanol, octylphenol, bisphenol A, and xylenol; the temperature T1 of the heat preservation reaction is 50°C to 70°C, and the time t1 is 2h to 7h; the mass ratio Y of the emulsifier to the phenolic compound is (0.08 to 0.13): 1; the temperature T2 of the heat preservation reaction is 80°C to 120°C, and the time t2 is 1h to 5h.
  • the molar ratio A can be 1:1.5:0.006, 1:2:0.006, 1:2.5:0.006, 1:1.5:0.009, 1:2:0.009, 1:2.5:0.009, 1:1.5:0.012, 1:2:0.012, 1:2.5:0.012, or a range consisting of any two ratios therebetween.
  • the temperature T1 can be 50°C, 60°C, 65°C, 70°C, or a range consisting of any two values therebetween.
  • the time t1 can be 2h, 3h, 4h, 5h, 6h, 7h, or a range consisting of any two values therebetween.
  • the porous carbon precursor is carbonized in an inert atmosphere, and then activated in an atmosphere containing a first compound to obtain a porous carbon matrix, wherein the first compound includes carbon dioxide or water vapor.
  • the carbonization temperature T3 is 450°C to 700°C, and the time t3 is 1 hour to 4 hours; the flow rate V1 of the first compound gas in the atmosphere containing the first compound is 1 L/min to 4 L/min, and the activation temperature T4 is 750°C to 1000°C, and the time t4 is 6 hours to 20 hours.
  • the temperature T3 may be 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, or a range consisting of any two values therebetween.
  • the time t3 may be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or a range consisting of any two values therebetween.
  • the flow rate V1 may be 1 L/min, 1.5 L/min, 2 L/min, 2.5 L/min, 3 L/min, 3.5 L/min, 4 L/min, or a range consisting of any two values therebetween.
  • the temperature T4 may be 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, or a range consisting of any two values therebetween.
  • time t4 may be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, or a range consisting of any two values therebetween.
  • the porous carbon matrix is pretreated in an inert atmosphere and then treated in a silane-containing atmosphere, and then the temperature is increased for heat preservation and then treated in an atmosphere containing a second compound to obtain a silicon-carbon material, wherein the second compound includes acetylene, propylene or toluene.
  • the pretreatment temperature T5 is 420°C to 550°C, and the time t5 is 1h to 3h;
  • the silane-containing atmosphere includes at least one of monosilane, disilane, trisilane, phenylsilane, and tolylsilane, and the flow rate V2 of the silane gas in the silane-containing atmosphere is 1L/min to 3L/min, and the ventilation time t6 is 220min to 480min;
  • the heat preservation temperature T7 is 450°C. to 600° C., time t7 is 0.5 h to 2 h;
  • the flow rate V3 of the second compound in the atmosphere containing the second compound is 3 L/min to 10 L/min, and the ventilation time t8 is 160 min to 400 min.
  • the temperature T5 can be 420°C, 425°C, 450°C, 475°C, 500°C, 525°C, 550°C, or a range consisting of any two values therebetween.
  • the time t5 can be 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or a range consisting of any two values therebetween.
  • the flow rate V2 can be 1 L/min, 1.2 L/min, 1.5 L/min, 1.8 L/min, 2 L/min, 2.2 L/min, 2.5 L/min, 2.8 L/min, 3 L/min, or a range consisting of any two values therebetween.
  • the ventilation duration t6 can be 220 min, 250 min, 275 min, 300 min, 325 min, 350 min, 375 min, 400 min, 420 min, 440 min, 460 min, 480 min, or a range consisting of any two values therebetween.
  • the temperature T7 can be 450°C, 475°C, 500°C, 525°C, 550°C, 575°C, 600°C, or a range consisting of any two values therebetween.
  • the time t7 can be 0.5h, 0.7h, 0.9h, 1h, 1.2h, 1.4h, 1.5h, 1.7h, 2h, or a range consisting of any two values therebetween.
  • the flow rate V3 can be 3L/min, 4L/min, 5L/min, 6L/min, 7L/min, 8L/min, 9L/min, 10L/min, or a range consisting of any two values therebetween.
  • the ventilation duration t8 can be 160min, 180min, 200min, 225min, 250min, 275min, 300min, 325min, 350min, 375min, 400min, or a range consisting of any two values therebetween.
  • the porous carbon precursor obtained by the above step (1) has fewer sharp corners, which is conducive to obtaining silicon-carbon compounds with high sphericity in the subsequent process.
  • the activation treatment in step (2) makes the pores inside the porous carbon precursor more abundant, and the obtained porous carbon matrix is conducive to the subsequent deposition of silicon materials.
  • step (3) pretreatment is first performed to improve the temperature uniformity of the porous carbon, which is conducive to the uniform deposition of silane in different porous carbon particles; then silane gas is introduced to deposit silicon materials in the pores of the porous carbon matrix; after heating, heat preservation treatment is performed to improve the temperature uniformity of the porous carbon after silicon deposition, which is conducive to the uniform decomposition and coating of the carbon source gas on the surface of different porous carbon particles; finally, the gas containing the second compound is introduced to cover the surface of the silicon material with higher activity with carbon material, thereby preventing the silicon material from oxidizing in the air environment and improving the stability of the silicon-carbon material.
  • the spherical degree A of the silicon-carbon material obtained is 0.80 to 0.98, which cooperates with the negative electrode current collector with a thickness of B ⁇ m.
  • the values of A and 3.14/A-0.048B are regulated within the above range.
  • the spherical degree of the silicon-carbon material matches the thickness of the negative electrode current collector.
  • the silicon-carbon material particles will not puncture the negative electrode current collector, and the problem of the sharp corners of the silicon-carbon material affecting the electron transmission channel of the negative electrode current collector is improved, thereby improving the charging rate and discharge rate of the secondary battery.
  • the term "negative electrode material layer disposed on at least one surface of the negative electrode current collector” means that the negative electrode material layer can be disposed on one surface of the negative electrode current collector along its thickness direction, or on both surfaces of the negative electrode current collector along its thickness direction. It should be noted that the "surface” here can refer to the entire surface of the negative electrode current collector or a portion of the surface of the negative electrode current collector. This is not particularly limited in this application, as long as the purpose of this 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 binder may include, but is not limited to, 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, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polyvinyl pyrrolidone, polyethylene, polypropylene, acrylic acid (ester) styrene-butadiene rubber, epoxy resin or nylon or polyvinylidene fluoride.
  • 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 the purpose of the present application can be achieved.
  • the present application has no particular limitation on the thickness of the negative electrode material layer, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode material layer is 30 ⁇ m to 120 ⁇ m.
  • the present application has no particular limitation on the thickness of the negative electrode current collector, as long as the purpose of the present application can be achieved.
  • the thickness of the negative electrode current collector is 4 ⁇ m to 15 ⁇ m.
  • the negative electrode sheet may further include a conductive layer positioned between the negative electrode current collector and the negative electrode material layer.
  • a conductive layer positioned between the negative electrode current collector and the negative electrode material layer.
  • the present application does not particularly limit the composition of the conductive layer, and it may be any conductive layer commonly used in the art.
  • the conductive layer may include a conductive agent and a binder.
  • the present application does not particularly limit the conductive agent and binder in the conductive layer, and for example, it may be at least one of the above-mentioned conductive agents and binders.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode material layer disposed on at least one surface of the positive electrode current collector.
  • the phrase "positive electrode material layer disposed on at least one surface of the positive electrode current collector” means that the positive electrode material layer can be disposed on one surface of the positive electrode current collector along its thickness direction, or on both surfaces of the positive electrode current collector along its thickness direction.
  • the "surface” here can refer to the entire surface of the positive electrode current collector or a portion of the surface of the positive electrode current collector. This is not particularly limited in the present application, as long as the purpose of this application can be achieved.
  • 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 thickness of the positive electrode current collector and the positive electrode material layer is not particularly limited in this application, as long as the purpose of this application can be achieved.
  • the thickness of the positive electrode current collector is 5 ⁇ m to 20 ⁇ m
  • the thickness of the positive electrode material layer is 30 ⁇ m to 120 ⁇ m.
  • 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 present application is not particularly limited to inorganic particles.
  • inorganic particles may 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 present application is not particularly limited to a binder.
  • a binder may include but is not limited to at least one of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyethylene alkoxy, polymethyl methacrylate, polytetrafluoroethylene or polyhexafluoropropylene.
  • the polymer layer includes a polymer
  • the material of the polymer includes at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylic acid salt, polyvinylpyrrolidone, polyvinyl ether or polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
  • 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.
  • the carbonate compound may include but is not limited to at least one of a chain carbonate compound, a cyclic carbonate compound or a fluorinated carbonate compound.
  • the chain carbonate compound may include but is not limited to dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC) or carbonic acid ester. At least one of ethyl methyl carbonate (EMC).
  • the above-mentioned cyclic carbonate may include but is 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
  • carboxylate compounds may include but are 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, valerolactone or caprolactone.
  • the above-mentioned ether compounds may include but are not limited to at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, 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 a positive electrode sheet, a separator, a negative electrode sheet and an electrolyte, as well as other components known in the field of secondary batteries.
  • a shell for accommodating a positive electrode sheet, a separator, a negative electrode sheet and an 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 has no special restrictions on 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.
  • the flexible shell can be a metal plastic film, such as an aluminum plastic film, a steel plastic film, etc.
  • the secondary battery of the present application includes, but is not limited to: a lithium ion battery or a sodium ion battery. In some embodiments of the present application, the secondary battery includes a lithium ion battery.
  • the third aspect of the present application provides an electronic device comprising the secondary battery or the front battery in any of the aforementioned embodiments.
  • 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.
  • the sphericity of the material is tested using the equivalent diameter method.
  • the complete particles tested above are particles with a longest diameter greater than 10 ⁇ m. The longest diameter of the silicon-carbon material particles refers to the maximum value between two points in the particle section contour.
  • the silicon-carbon material was observed in a cross-section of the negative electrode sheet along its thickness using a ZEISS-SEM (Sigma-02-33).
  • the silicon content of the silicon-carbon material was measured using an energy dispersive spectrometer (EDS).
  • EDS energy dispersive spectrometer
  • the silicon-carbon material in the cross section of the negative electrode sheet along the thickness direction was observed using ZEISS-SEM (sigma-02-33).
  • the silicon content of the silicon-carbon material was tested using an energy dispersive spectrometer (EDS) method, and the silicon content of 50 particles was counted and the average value was calculated.
  • EDS energy dispersive spectrometer
  • the fracture strength F of the negative electrode current collector was tested with reference to the standard "GB/T 5230-1995 Electrolytic copper foil tensile strength, elastic modulus and elongation at break test".
  • the prepared lithium-ion battery was discharged at a constant current rate of 0.2C to 3.0V and allowed to stand for 5 minutes. It was then charged at a constant current rate of 0.5C to 4.5V, and charged at a constant voltage of 4.5V to 0.05C, and allowed to stand for 5 minutes. It was then discharged at a constant current rate of 0.2C to 3.0V, and allowed to stand for 5 minutes. The discharge capacity of this step was recorded as C1. It was then charged at a constant current rate of 0.2C1 to 4.5V, and charged at a constant voltage of 4.5V to 0.05C, and allowed to stand for 5 minutes. The charge capacity of this step was recorded as C2. It was then discharged at a constant current rate of 2C1 to 3.0V, and the discharge capacity of this step was recorded as C3.
  • the prepared lithium-ion battery was discharged at a constant current rate of 0.2C to 3.0V and allowed to stand for 5 minutes; then charged at a constant current rate of 0.5C to 4.5V, and charged at a constant voltage of 4.5V to 0.05C, and allowed to stand for 5 minutes; then discharged at a constant current rate of 0.2C to 3.0V, and allowed to stand for 5 minutes, and the discharge capacity of this step was recorded as C1. Then, the battery was charged at a constant current rate of 0.2C1 to 4.5V, and charged at a constant voltage to 0.05C, and allowed to stand for 5 minutes, and the charge capacity of this step was recorded as C2;
  • the coating weight of the negative electrode material layer was 100.1 mg/1540 mm2 .
  • the above steps were repeated on the other surface of the copper foil to produce a double-sided negative electrode sheet coated with the negative electrode material layer. After cold pressing, cutting, slitting, and welding the tabs, a negative electrode sheet measuring 661 mm x 78 mm was obtained for later use.
  • the thickness of the single-sided negative electrode material layer is 54.5 ⁇ m.
  • the negative electrode active material is obtained by mixing the silicon-carbon material prepared above and graphite in a mass ratio of 1:9, and the gram capacity of the negative electrode active material is 480 mAh/g.
  • the positive electrode active material LiCoO2 , the conductive agent acetylene black, and the binder polyvinylidene fluoride were mixed in a mass ratio of 96.7:1.7:1.6.
  • N-methylpyrrolidone (NMP) was added as a solvent to form a slurry with a solid content of 76 wt%. After vacuum stirring, the slurry was evenly coated on one surface of a 9 ⁇ m thick positive electrode current collector aluminum foil and dried at 120°C to obtain a single-sided positive electrode sheet coated with a positive electrode material layer.
  • the coating weight of the positive electrode material layer was 260 mg/1540 mm2 .
  • a porous polyethylene film with a thickness of 10 ⁇ m (supplied by Celgard) was used as a separator.
  • 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.
  • the minimum angle ⁇ of the cross-sectional profile of the silicon-carbon material, the mass percentage of the silicon element W1, and the mass percentage of the oxygen element W2 vary with the changes in the preparation parameters.
  • the silicon-carbon compound prepared by the preparation method of this application is prepared, the above parameters are all within the scope of this application, and the resulting lithium-ion battery has a high charge rate and discharge rate.
  • FIG2 shows the silicon-carbon compound prepared in Example 9.
  • the cross section of the silicon-carbon compound particles is close to circular.
  • the minimum angle ⁇ of the cross section of the silicon-carbon compound particles is measured to be 179.2.
  • the thickness B and tensile strength F of the negative electrode current collector are positively correlated, which will affect the charge rate and discharge rate of the secondary battery.
  • the thickness B and tensile strength F of the negative electrode current collector are within the range of this application, the lithium-ion battery has a high charge rate and discharge rate.

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Abstract

一种二次电池及其制备方法、电子装置，二次电池包括正极极片、负极极片、电解液以及隔膜；负极极片包括负极集流体和设置在负极集流体至少一个表面上的负极材料层，负极材料层包括硅碳材料；硅碳材料中最长径大于10μm颗粒的球形化度为A度，A为0.80至0.98，其中，负极集流体的厚度为Bμm，A和B的关系为3.14/A-0.048B≤3.7。通过调控A和3.14/A-0.048B的值的在上述范围内，硅碳材料的球形化度与负极集流体的厚度相互匹配，硅碳材料颗粒不会刺破负极集流体，并且改善硅碳材料棱角影响负极集流体电子传输通道的问题，从而二次电池的充电倍率和放电倍率得以提高。

Description

一种二次电池及其制备方法、电子装置 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及其制备方法、电子装置。
背景技术
随着传统能源的持续消耗，以及对大规模存储、电动汽车和便携式电子设备的急迫需求，开发更高能量密度的能源储存设备成为当务之急。二次电池，如锂离子电池，其因无记忆效应、长循环寿命、绿色环保等优点，广泛应用在如今生活的各个方面。近年来，锂离子电池更是在新能源汽车和大规模储能领域得到了迅猛发展。然而，石墨作为传统商品化锂离子电池的负极材料，较低的容量(372mAh/g)阻碍了其进一步应用。开发高能量密度和高安全性的锂离子电池负极材料是目前锂电技术发展的重点。和石墨等碳基材料相比，硅由于超高的理论比容量(Li15Si4，3579mAh/g)和合适的工作电压(<0.5V vs.Li/Li+)等特点，被认为是可以替代石墨的最有前途的锂电负极材料。然而，负极中添加硅的电池常因动力学不足造成快充能力下降和界面析锂。造成这些问题的主要原因之一是不规则形状硅材料颗粒具有尖锐的棱角，这些尖角会在负极加工时刺破铜箔集流体，造成集流体中的电子传输通道被破坏，导致电池内部阻抗增大，继而引发动力学不足的问题，使得锂离子电池的充电倍率和放电倍率降低。
发明内容
本申请的目的在于提供一种二次电池及其制备方法、电子装置，以提高二次电池的充电倍率和放电倍率。具体技术方案如下：
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，其包括正极极片、负极极片、电解液以及隔膜；所述负极极片包括负极集流体和设置在所述负极集流体至少一个表面上的负极材料层，所述负极材料层包括硅碳材料；所述硅碳材料中最长径大于10μm颗粒的球形化度为A度，A为0.80至0.98，其中，所述负极集流体的厚度为Bμm，A和B的关系为3.14/A-0.048B≤3.7。通过调控A和3.14/A-0.048B的值的在上述范围内，硅碳材料的球形化度与负极集流体的厚度相互匹配，硅碳材料颗粒不会刺破负极集流体，并且改善硅碳材 料棱角影响负极集流体电子传输通道的问题，从而二次电池的充电倍率和放电倍率得以提高。
在本申请的一些实施方案中，A为0.84至0.98，可进一步提高二次电池的充电倍率和放电倍率。
在本申请的一些实施方案中，2.2≤3.14/A-0.048B≤3.6，可进一步促进负极集流体电子传输，改善二次电池的充电倍率和放电倍率。在本申请的一些实施方案中，2.7≤3.14/A-0.048B≤3.5。
在本申请的一些实施方案中，3.5≤B≤20。通过调控B的值在上述范围内，负极集流体具有合适的厚度，与硅碳材料的球形化度相互匹配，二次电池的充电倍率和放电倍率得以提高。
在本申请的一些实施方案中，所述负极集流体的拉伸断裂强度为451MPa至950MPa。负极集流体的拉伸断裂强度在上述范围内，说明负极集流体具有较好的拉伸断裂强度，当硅碳材料颗粒的棱角刺入负极集流体时，负极集流体不易破裂且对其电子传输通道影响小，从而有利于提高二次电池的充电倍率和放电倍率。在本申请的一些实施方案中，负极集流体的拉伸断裂强度F为470MPa至700Mpa。
在本申请的一些实施方案中，所述硅碳材料中颗粒直径大于或等于10μm的颗粒的切面轮廓最小角为107.8°≤α≤179.2°。α在上述范围内，说明硅碳材料颗粒中没有尖锐的棱角，从而不易刺破负极集流体，碳材料棱角对负极集流体电子传输通道影响也较小，从而有利于提高二次电池的充电倍率和放电倍率。在本申请的一些实施方案中，110.3°≤α≤179.2°。
在本申请的一些实施方案中，所述硅碳材料中硅元素的质量百分含量为40％至54％。通过调控硅元素的质量百分含量在上述范围内，得到的硅碳化合物具有合适的比容量，且用于二次电池时具有合适的阻抗，从而有利于提高二次电池的充电倍率和放电倍率，同时二次电池还具有较高的能量密度。
在本申请的一些实施方案中，所述硅碳材料中氧元素的质量百分含量小于或等于1.5％。通过调控氧元素的质量百分含量在上述范围内，得到的硅碳化合物不易与电解液发生副反应，从而有利于提高二次电池的首次库伦效率。本申请的第二方面提供了一种前述任一实施方案中的二次电池的制备方法，其包括以下步骤：制备所述正极极片、所述负极极片、所述隔膜和所述电解液，组装得到所述二次电池；
其中，所述负极极片中的所述硅碳材料的制备方法包括以下步骤：
(1)将酚类化合物、甲醛、氨气与水混合，混合均匀后进行保温反应，再加入乳化剂，混合均匀后进行升温反应得到多孔碳前驱体；
其中，所述酚类化合物、甲醛、氨气的摩尔比为1:(1.5至2.5):(0.006至0.012)，所述酚类化合物包括苯酚、甲酚、壬基酚、芳烷基酚、腰果酚、辛基酚、双酚A、二甲酚中的至少一种；所述保温反应的温度T1为50℃至70℃、时间t1为2h至7h；所述乳化剂与所述酚类化合物的质量比为(0.08至0.13):1；所述升温反应的温度T2为80℃至120℃、时间t2为1h至5h；
(2)将所述多孔碳前驱体在惰性气氛下进行碳化处理，然后在含第一化合物的气氛中进行活化处理得到多孔碳基体，所述第一化合物包括二氧化碳或水蒸气；
其中，所述碳化处理的温度T3为450℃至700℃、时间t3为1h至4h；所述含第一化合物气氛中第一化合物气体的流速V1为1L/min至4L/min，所述活化处理的温度T4为750℃至1000℃、时间t4为6h至20h；
(3)将所述多孔碳基体在惰性气氛下进行预处理后在含硅烷气氛下进行处理，然后升温进行保温处理后在含第二化合物的气氛中进行处理得到所述硅碳材料，第二化合物包括乙炔、丙烯或甲苯；
其中，所述预处理的温度T5为420℃至550℃、时间t5为1h至3h；所述含硅烷气氛包括甲硅烷、乙硅烷、丙硅烷、苯基硅烷、甲苯基硅烷中的至少一种，所述含硅烷气氛中硅烷气体的流速V2为1L/min至3L/min、通气时长t6为220min至480min；保温处理的温度T7为450℃至600℃、时间t7为0.5h至2h；所述含第二化合物的气氛中第二化合物的流速V3为3L/min至10L/min、通气时长t8为160min至400min。
本申请的第三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或前述任一实施方案中的制备方法制得的二次电池。
本申请的有益效果：
本申请提供了一种二次电池及其制备方法、电子装置，二次电池包括正极极片、负极极片、电解液以及隔膜；负极极片包括负极集流体和设置在负极集流体至少一个表面上的负极材料层，负极材料层包括硅碳材料；硅碳材料中最长径大于10μm颗粒的球形化度为A度，A为0.80至0.98，其中，负极集流体的厚度为Bμm，A和B的关系为3.14/A-0.048B≤3.7。通过调控A和3.14/A-0.048B的值的在上述范围内，硅碳材料的球形化度与负极集流体的厚度相互匹配，硅碳材料颗粒不会刺破负极集流体，并且改善硅碳材料棱角影响负极集流体电子传输通道的问题，从而二次电池的充电倍率和放电倍率得以提高。
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为本申请一种实施方案中的硅碳材料颗粒的横切面所形成的外轮廓的结构示意图；
图2为本申请的实施例9的硅碳材料电镜照片。
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。具体技术方案如下：
目前，为了解决锂离子电池充电倍率和放电倍率差的问题，多采用降低负极压实密度、增加铜箔厚度、双层涂布以及减小硅材料颗粒尺寸等方法。降低负极压实密度和增加铜箔厚度虽然能在一定程度上缓解铜箔集流体被硅材料尖角刺破的问题，但同时也增加了锂离子电池中非活性物质的体积和重量，会降低锂离子电池的能量密度；双层涂布虽然可以减小硅材料与铜箔集流体的接触概率，但由于硅材料集中在负极片表面，活性物质层表面的电子和离子传输能力均发生恶化，易产生析锂等问题；减小颗粒尺寸虽然可以减弱硅材料尖角对铜箔的刺穿深度，但硅材料比表面积增加会生成更多的固态电解质界面膜(SEI膜)，对锂离子电池的首效有降低作用，因而也不是有效的解决方法。
有鉴于此，本申请提供一种二次电池及其制备方法、电子装置，以提高二次电池的充电倍率和放电倍率。
本申请的第一方面提供了一种二次电池，其包括正极极片、负极极片、电解液以及隔膜；负极极片包括负极集流体和设置在负极集流体至少一个表面上的负极材料层，负极材料层包括硅碳材料；硅碳材料中最长径大于10μm颗粒的球形化度为A度，A为0.80至0.98，在本申请的一些实施方案中，A为0.84至0.98，例如，A的值可以为0.80、0.81、0.82、0.83、0.84、0.85、0.86、0.87、0.88、0.9、0.92、0.94、0.96、0.98或为其间任意两 个数值组成的范围。负极集流体的厚度为Bμm，A和B的关系为3.14/A-0.048B≤3.7。在本申请的一些实施方案中，2.0≤3.14/A-0.048B≤3.7。在本申请的一些实施方案中，2.2≤3.14/A-0.048B≤3.6。在本申请的一些实施方案中，2.7≤3.14/A-0.048B≤3.5。例如，3.14/A-0.048B的值可以为2.0、2.1、2.2、2.3、2.4、2.5、2.6、2.7、2.8、2.9、3.0、3.1、3.2、3.3、3.4、3.5、3.6、3.7或为其间任意两个数值组成的范围。当A值过小时，例如小于0.80，硅碳材料的球形化度较低，棱角较多，容易刺入负极集流体，使得负极集流体的电子传输通道受损，从而影响二次电池的充电倍率和放电倍率。当A值过大，例如大于0.98，硅碳材料的生产成本高，使得二次电池的成本提高。当3.14/A-0.048B的值过大，例如大于3.7时，硅碳材料颗粒的球形化度相对负极集流体的厚度过低，硅碳材料颗粒的棱角刺入负极集流体的深度较深，使得负极集流体的电子传输通道受损，甚至刺破负极集流体，从而影响二次电池的充电倍率和放电倍率。从而，通过调控3.14/A-0.048B的值的在上述范围内，硅碳材料的球形化度与负极集流体的厚度相互匹配，硅碳材料颗粒不会刺破负极集流体，并且改善硅碳材料棱角影响负极集流体电子传输通道的问题，从而二次电池的充电倍率和放电倍率得以提高。
在本申请的一些实施方案中，3.5≤B≤20。在本申请的一些实施方案中，4.0≤B≤8.0。例如，B的值可以为3.5、4、5、6、7、8、9、10、12、14、15、17、19、20或为其间任意两个数值组成的范围。通过调控B的值在上述范围内，负极集流体具有合适的厚度，与硅碳材料的球形化度相互匹配，改善硅碳材料棱角影响负极集流体电子传输通道的问题，从而二次电池的充电倍率和放电倍率得以提高。
在本申请的一些实施方案中，负极集流体的厚度为6μm至20μm，负极集流体的拉伸断裂强度F为451MPa至950MPa。在本申请的一些实施方案中，负极集流体的拉伸断裂强度F为470MPa至700Mpa。例如，拉伸断裂强度F可以为451MPa、460MPa、470MPa、500MPa、600MPa、700MPa、800MPa、900MPa、950MPa、或为其间任意两个数值组成的范围。负极集流体的拉伸断裂强度F在上述范围内，说明负极集流体具有较好的拉伸断裂强度，当硅碳材料颗粒的棱角刺入负极集流体时，负极集流体不易破裂且对其电子传输通道影响小，从而有利于提高二次电池的充电倍率和放电倍率。
在本申请中，不同厚度和拉伸断裂强度的负极集流体可以通过购买得到，并结合本申请提供的“负极集流体的厚度B的测试”、“负极集流体的拉伸断裂强度F的测试”测试方法，选择所需的厚度和拉伸断裂强度的负极集流体即可。
在本申请的一些实施方案中，硅碳材料中颗粒直径大于或等于10μm的颗粒的切面轮廓最小角为107.8°≤α≤179.2°。在本申请的一些实施方案中，110.3°≤α≤179.2°。例如，α可以为107.8、110.3°、110.5°、111°、115°、120°、130°、140°、150°、160°、170°、175°、179°、179.2°或为其间任意两个数值组成的范围。直径大于或等于10μm的颗粒切面轮廓最小角更具代表性，α在上述范围内，说明硅碳材料颗粒中没有尖锐的棱角，从而不易刺破负极集流体，碳材料棱角对负极集流体电子传输通道影响也较小，从而有利于提高二次电池的充电倍率和放电倍率。
在本申请中，硅碳材料颗粒切面轮廓最小角α是指颗粒的横切面所形成的外轮廓的棱角的角度中的最小值，棱角的角度是指沿棱角两侧的边缘做切线，两条切线之间所形成的夹角的角度。具体地，图1为硅碳材料颗粒的横切面所形成的外轮廓的结构示意图，α1为115°、α2为108°、α3为142°、α4为140°，则切面轮廓最小角α为108°。
在本申请的一些实施方案中，硅碳材料中硅元素的质量百分含量W1为40％至54％。例如，硅元素的质量百分含量W1可以为40％、41％、42％、43％、44％、45％、46％、47％、48％、49％、50％、51％、52％、53％、54％或为其间任意两个数值组成的范围。通过调控硅元素的质量百分含量W1在上述范围内，得到的硅碳化合物具有合适的比容量，且用于二次电池时具有合适的阻抗，从而有利于提高二次电池的充电倍率和放电倍率，同时二次电池还具有较高的能量密度。
在本申请的一些实施方案中，硅碳材料中氧元素的质量百分含量W2小于或等于1.5％。在本申请的一些实施方案中，硅碳材料中氧元素的质量百分含量W2为0.01％至1.5％。例如，氧元素的质量百分含量W2可以为0.01％、0.1％、0.2％、0.3％、0.4％、0.5％、0.6％、0.7％、0.8％、0.9％、1％、1.1％、1.2％、1.3％、1.4％、1.5％或为其间任意两个数值组成的范围。通过调控氧元素的质量百分含量W2在上述范围内，得到的硅碳化合物不易与电解液发生副反应，从而有利于提高二次电池的首次库伦效率。
在本申请的一些实施方案中，硅碳材料中碳元素的质量百分含量W3为46％至59％。可进一步提高二次电池的充电倍率和放电倍率。
本申请的第二方面提供了一种前述任一实施方案中的二次电池的制备方法，其包括以下步骤：制备正极极片、负极极片、隔膜和电解液，组装得到二次电池；
其中，负极极片中的硅碳材料的制备方法包括以下步骤：
(1)将酚类化合物、甲醛、氨气与水混合，混合均匀后进行保温反应，再加入乳化 剂，混合均匀后进行升温反应得到多孔碳前驱体。其中，酚类化合物、甲醛、氨气的摩尔比X为1:(1.5至2.5):(0.006至0.012)，酚类化合物包括苯酚、甲酚、壬基酚、芳烷基酚、腰果酚、辛基酚、双酚A、二甲酚中的至少一种；保温反应的温度T1为50℃至70℃、时间t1为2h至7h；乳化剂与酚类化合物的质量比Y为(0.08至0.13):1；升温反应的温度T2为80℃至120℃、时间t2为1h至5h。
例如，摩尔比A可以为1:1.5:0.006、1:2:0.006、1:2.5:0.006、1:1.5:0.009、1:2:0.009、1:2.5:0.009、1:1.5:0.012、1:2:0.012、1:2.5:0.012或为其间任意两个比值组成的范围。例如，温度T1可以为50℃、60℃、65℃、70℃或为其间任意两个数值组成的范围。例如，时间t1可以为2h、3h、4h、5h、6h、7h或为其间任意两个数值组成的范围。例如，质量比B可以为0.08:1、0.09:1、0.10:1、0.11:1、0.12:1、0.13:1或为其间任意两个比值组成的范围。例如，温度T2可以为80℃、85℃、90℃、95℃、100℃、105℃、110℃、115℃、120℃或为其间任意两个数值组成的范围。例如，时间t2可以为1h、1.5h、2h、2.5h、3h、3.5h、4h、4.5h、5h或为其间任意两个数值组成的范围。
(2)将多孔碳前驱体在惰性气氛下进行碳化处理，然后在含第一化合物的气氛中进行活化处理得到多孔碳基体，第一化合物包括二氧化碳或水蒸气。其中，碳化处理的温度T3为450℃至700℃、时间t3为1h至4h；含第一化合物气氛中第一化合物气体的流速V1为1L/min至4L/min，活化处理的温度T4为750℃至1000℃、时间t4为6h至20h。
例如，温度T3可以为450℃、500℃、550℃、600℃、650℃、700℃或为其间任意两个数值组成的范围。例如，时间t3可以为1h、1.5h、2h、2.5h、3h、3.5h、4h或为其间任意两个数值组成的范围。例如，流速V1可以为1L/min、1.5L/min、2L/min、2.5L/min、3L/min、3.5L/min、4L/min或为其间任意两个数值组成的范围。例如，温度T4可以为750℃、800℃、850℃、900℃、950℃、1000℃或为其间任意两个数值组成的范围。例如，时间t4可以为6h、7h、8h、9h、10h、11h、12h、13h、14h、15h、16h、17h、18h、19h、20h或为其间任意两个数值组成的范围。
(3)将多孔碳基体在惰性气氛下进行预处理后在含硅烷气氛下进行处理，然后升温进行保温处理后在含第二化合物的气氛中进行处理得到硅碳材料，第二化合物包括乙炔、丙烯或甲苯。其中，预处理的温度T5为420℃至550℃、时间t5为1h至3h；含硅烷气氛包括甲硅烷、乙硅烷、丙硅烷、苯基硅烷、甲苯基硅烷中的至少一种，含硅烷气氛中硅烷气体的流速V2为1L/min至3L/min、通气时长t6为220min至480min；保温处理的温度T7为450℃ 至600℃、时间t7为0.5h至2h；含第二化合物的气氛中第二化合物的流速V3为3L/min至10L/min、通气时长t8为160min至400min。
例如，温度T5可以为420℃、425℃、450℃、475℃、500℃、525℃、550℃或为其间任意两个数值组成的范围。例如，时间t5可以为1h、1.5h、2h、2.5h、3h或为其间任意两个数值组成的范围。例如，流速V2可以为1L/min、1.2L/min、1.5L/min、1.8L/min、2L/min、2.2L/min、2.5L/min、2.8L/min、3L/min或为其间任意两个数值组成的范围。例如，通气时长t6可以为220min、250min、275min、300min、325min、350min、375min、400min、420min、440min、460min、480min或为其间任意两个数值组成的范围。例如，温度T7可以为450℃、475℃、500℃、525℃、550℃、575℃、600℃或为其间任意两个数值组成的范围。例如，时间t7可以为0.5h、0.7h、0.9h、1h、1.2h、1.4h、1.5h、1.7h、2h或为其间任意两个数值组成的范围。例如，流速V3可以为3L/min、4L/min、5L/min、6L/min、7L/min、8L/min、9L/min、10L/min或为其间任意两个数值组成的范围。例如，通气时长t8可以为160min、180min、200min、225min、250min、275min、300min、325min、350min、375min、400min或为其间任意两个数值组成的范围。
通过上述步骤(1)得到的多孔碳前驱体的颗粒尖角少，在后续有利于得到球形度高的硅碳化合物。通过步骤(2)中的活化处理，使得多孔碳前驱体内部的孔隙更加丰富，得到的多孔碳基体有利于后续沉积硅材料。步骤(3)中，先通过预处理，可以提高多孔碳的温度均匀性，有利于硅烷在不同多孔碳颗粒中均匀沉积；然后通入硅烷气体在多孔碳基体的孔隙中沉积硅材料；升温后进行保温处理，可以提高沉积硅后多孔碳的温度均匀性，有利于碳源气体在不同多孔碳颗粒表面均匀分解包覆；最后通入含第二化合物的气体，可以使活性较高的硅材料表面覆盖碳材料，防止硅材料在空气环境中氧化，提高硅碳材料的稳定性。从而得到的硅碳材料的球形化度A为0.80至0.98，与厚度为Bμm的负极集流体相互配合，调控A和3.14/A-0.048B的值的在上述范围内，硅碳材料的球形化度与负极集流体的厚度相互匹配，硅碳材料颗粒不会刺破负极集流体，并且改善硅碳材料棱角影响负极集流体电子传输通道的问题，从而二次电池的充电倍率和放电倍率得以提高。
本申请对步骤(1)中加入的水的含量没有特别限制，只要能实现本申请的目的即可，例如，水的加入质量为酚类化合物质量的5倍至15倍。本申请对步骤(2)和(3)中惰性气氛中的气体组成和流速不做限定，示例性地，惰性气氛中的气体可以包括但不限于氮气、氩气、氦气等，流速可以为1L/min至10L/min。
在本申请中，上述“设置在负极集流体至少一个表面上的负极材料层”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。
上述硅碳化合物可以作为负极材料层中的负极活性材料，负极材料层还可以包括其它负极活性材料，本申请对其它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，其它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、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，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。例如，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、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、聚乙烯吡咯烷酮、聚乙烯、聚丙烯、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙或聚偏二氟乙烯中的至少一种。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。
在本申请中，正极极片包括正极集流体以及设置于正极集流体至少一个表面上的正极材料层。上述“设置于正极集流体至少一个表面上的正极材料层”是指，正极材料层可以设置于正极集流体沿自身厚度方向上的一个表面上，也可以设置于正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”可以是正极集流体表面的全部区域，也可以是正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，可以是上述导电剂和上述粘结剂中的至少一种。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。
本申请对正极集流体和正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，正极集流体的厚度为5μm至20μm，正极材料层的厚度为30μm至120μm。
任选地，正极极片还可以包含导电层，导电层位于正极集流体和正极材料层之间。导电层的组成没有特别限制，可以是本领域常用的导电层。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。
在本申请中，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，例如粘结剂可以包括但不限于聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯烷氧、聚甲基丙烯酸甲酯、聚四氟乙烯或聚六氟丙烯中的至少一种。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，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(EMC)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。
在本申请中，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。
在本申请的一些实施方案中，本申请的二次电池包括，但不限于：锂离子电池或钠离子电池。在本申请的一些实施方案中，二次电池包括锂离子电池。
本申请的第三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或前 述任一实施方案中的制备方法制得的二次电池。
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：
硅碳材料颗粒切面轮廓最小角α的测试：
将0.47g硅碳材料和0.396g聚丙烯酸分散到水中，在匀浆机中混匀后用刮刀涂布到铜箔表面，烘干后用日本电子/IB-09010CP离子抛光仪进行切片处理。采用ZEIS-SEM(sigma-02-33)拍摄硅碳材料的切面显微图像。选取硅碳材料颗粒直径大于或等于10μm颗粒切面轮廓进行分析，统计50个颗粒的轮廓中最小角的度数并求平均值作为最终结果。硅碳材料颗粒直径是指颗粒切面轮廓中两点之间的最大值。
硅碳材料中最长径大于10μm颗粒的球形化度A的测试：
利用等效直径法测试材料的球形化度，测试方法为采用ZEISS-SEM(sigma-02-33)扫描电子显微镜观察负极极片沿厚度方向的横截面中的硅碳材料，剔除不完整颗粒，对完整颗粒的周长等效直径与颗粒面积等效直径进行计算并求平均值计算球形化度。其中，球形化度＝周长等效直径/面积等效直径。上述测试的完整颗粒为最长径大于10μm的颗粒，硅碳材料颗粒最长径是指颗粒切面轮廓中两点之间的最大值
硅碳材料中硅元素的质量百分含量W1的测试：
采用ZEISS-SEM(sigma-02-33)对负极极片沿厚度方向的横截面中的硅碳材料进行观察。利用能谱仪(EDS)方法测试硅碳材料的硅含量，统计50个颗粒的硅含量并求平均值。
硅碳材料中氧元素的质量百分含量W2的测试：
采用ZEISS-SEM(sigma-02-33)对负极极片沿厚度方向的横截面中的硅碳材料进行观 察。利用能谱仪(EDS)方法测试硅碳材料的硅含量，统计50个颗粒的硅含量并求平均值。
负极集流体的厚度B的测试：
采用千分尺对负极集流体任选10处进行厚度测试，取平均值作为最终结果。
负极集流体的拉伸断裂强度F的测试：
参照标准《GB/T 5230-1995电解铜箔拉伸强度、弹性模量、断裂伸长率试验》对负极集流体的断裂强度F进行测试。
锂离子电池放电倍率性能测试：
在25℃、常压环境下，将制备的锂离子电池以0.2C倍率恒流放电至3.0V，静置5min；以0.5C倍率恒流充电至4.5V，并以4.5V恒压充电至0.05C，静置5min；再以0.2C倍率恒流放电至3.0V，静置5min，记录该步放电容量为C1。以0.2C1倍率恒流充电至4.5V，并以4.5V恒压充电至0.05C，静置5min，记录该步充电容量为C2；以2C1恒流放电至3.0V，记录该步放电容量为C3。
电池的放电倍率性能＝C3/C2×100％。
锂离子电池充电倍率性能测试
在25℃、常压环境下，将制备的锂离子电池以0.2C倍率恒流放电至3.0V，静置5min；以0.5C倍率恒流充电至4.5V，并以4.5V恒压充电至0.05C，静置5min；再以0.2C倍率恒流放电至3.0V，静置5min，记录该步放电容量为C1。以0.2C1倍率恒流充电至4.5V，并恒压充电至0.05C，静置5min，记录该步充电容量为C2；
电池的放电倍率性能＝C2/C1×100％。
实施例1
<硅碳材料的制备>
(1)将酚类化合物间苯酚、甲醛、氨气按照摩尔比X为1:2.0:0.01混合，加入水混合均匀后进行保温反应，水的加入质量为酚类化合物质量的10倍，保温反应的温度T1为60℃、时间t1为6h；再加入乳化剂F127，乳化剂与酚类化合物的质量比Y为0.08:1，搅拌1h，混合均匀后进行升温反应，升温反应的温度T2为100℃、时间t2为4h；反应结束后将反应后的溶液过滤及洗涤后得到多孔碳前驱体。
(2)将1000g多孔碳前驱体在氮气气氛下进行碳化处理，氮气的流速为2L/min，碳化处理的温度T3为600℃、时间t3为3h；升高温度，然后在含第一化合物的气氛中进行活化处理得到多孔碳基体，第一化合物为二氧化碳，第一化合物气体的流速V1为3L/min，活化处 理的温度T4为930℃、时间t4为20h。
(3)将1000g多孔碳基体加入流化床反应器中，在氮气气氛下进行预处理，氮气的流速为10L/min，预处理的温度T5为480℃、时间t5为1h；然后通入含硅烷的气体，含硅烷气体中的硅烷为甲硅烷，硅烷的流速V2为2L/min、通气时长t6为340min；然后继续升温进行保温处理，保温处理的温度T7为500℃、时间t7为1h；然后在含第二化合物的气氛下进行处理得到硅碳材料，第二化合物为乙炔，第二化合物气体的流速V3为8L/min、通气时长t8为300min。
<负极极片的制备>
将上述制备得到的硅碳材料和人造石墨按照质量比1:9进行混合后作为负极活性材料，将负极活性材料、碳纳米管、羧甲基纤维素锂、聚丙烯酸锂按照质量比97.4:0.2:0.4:2，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，粘度为6000mPa.s。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，得到单面涂布负极材料层的负极极片，负极材料层的涂布重量为100.1mg/1540mm2。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材料层的负极极片。经冷压、裁片、分切、焊接极耳后，得到规格为661mm×78mm的负极极片待用。其中，单面负极材料层的厚度为54.5μm。其中，负极活性材料由上述制备的硅碳材料和石墨按照质量比为1:9混合得到，负极活性材料的克容量为480mAh/g。
<正极极片的制备>
将正极活性材料LiCoO2、导电剂乙炔黑、粘结剂聚偏二氟乙烯按照质量比96.7:1.7:1.6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76wt％的浆料，真空搅拌均匀后得到正极浆料。将正极浆料均匀涂覆在厚度为9μm的正极集流体铝箔的一个表面上，120℃条件下烘干，得到单面涂布正极材料层的正极极片，正极材料层的涂布重量为260mg/1540mm2。然后在铝箔的另一个表面上重复以上步骤，即得到双面涂布正极材料层的正极极片。经冷压、裁片、分切、焊接极耳，得到规格为661mm×76.5mm的正极极片待用。其中，单面正极材料层的厚度为42μm。
<电解液的制备>
在含水量小于10ppm的环境下，将氟代碳酸乙烯酯(FEC)、碳酸乙烯酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按照质量比为5:10:15:20:50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，电解质盐的质量百分含量为12.5％，其余为有机溶剂。
<隔膜>
采用厚度为10μm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，化成上限电压为4.15V，化成温度为70℃，化成静置时间为2h。
实施例2至实施例15
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1至对比例2
除了不加入乳化剂并按照表1调整相关制备参数以外，其余与实施例1相同。
对比例3至对比例5
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。
各实施例及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15、对比例1至对比例5可以看出，当硅碳材料的球形化度A和3.14/A-0.048B的值同时在本申请的范围内时，得到的锂离子电池具有高的充电倍率和放电倍率，从而说明锂离子电池的充电倍率和放电倍率得到提高。
从实施例1至实施例15可以看出，硅碳材料的切面轮廓最小角α、硅元素的质量百分含量W1、氧元素的质量百分含量W2随制备参数的变化而变化，当采用本申请中的制备方法制得的硅碳化合物，上述参数均在本申请的范围内，得到锂离子电池具有高的充电倍率和放电倍率。
具体地，图2为实施例9中制备得到的硅碳化合物，从图中可以看出，硅碳化合物颗粒的截面接近圆形，经测量硅碳化合物颗粒的切面轮廓最小角α为179.2。
从实施例1至实施例15可以看出，负极集流体的厚度B和拉伸断裂强度F呈正相关，其会影响二次电池的充电倍率和放电倍率，当负极集流体的厚度B和拉伸断裂强度F在本申请的范围内时，得到锂离子电池具有高的充电倍率和放电倍率。
需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法或物品不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法或物品所固有的要素。
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 (10)

  1. 一种二次电池，其包括正极极片、负极极片、电解液以及隔膜；所述负极极片包括负极集流体和设置在所述负极集流体至少一个表面上的负极材料层，所述负极材料层包括硅碳材料；所述硅碳材料中最长径大于10μm颗粒的球形化度为A，A为0.80至0.98，其中，所述负极集流体的厚度为Bμm，A和B的关系为3.14/A-0.048B≤3.7。
  2. 根据权利1所述的二次电池，其中，3.5≤B≤20。
  3. 根据权利要求1或2所述的二次电池，其中，所述负极集流体的拉伸断裂强度为451MPa至950MPa。
  4. 根据权利要求1至3中任一项所述的二次电池，其中，所述硅碳材料中颗粒直径大于或等于10μm的颗粒的切面轮廓最小角为107.8°≤α≤179.2°。
  5. 根据权利要求1至4中任一项所述的二次电池，其中，所述硅碳材料中硅元素的质量百分含量为40％至54％。
  6. 根据权利要求1至5中任一项所述的二次电池，其中，所述硅碳材料中氧元素的质量百分含量小于或等于1.5％。
  7. 根据权利要求1至6中任一项所述的二次电池，其中，A为0.84至0.98。
  8. 根据权利要求1至7中任一项所述的二次电池，其中，2.2≤3.14/A-0.048B≤3.6。
  9. 一种权利要求1至8中任一项所述的二次电池的制备方法，其包括以下步骤：制备所述正极极片、所述负极极片、所述隔膜和所述电解液，组装得到所述二次电池；
    其中，所述负极极片中的所述硅碳材料的制备方法包括以下步骤：
    (1)将酚类化合物、甲醛、氨气与水混合，混合均匀后进行保温反应，再加入乳化剂，混合均匀后进行升温反应得到多孔碳前驱体；
    其中，所述酚类化合物、甲醛、氨气的摩尔比为1:(1.5至2.5):(0.006至0.012)，所述酚类化合物包括苯酚、甲酚、壬基酚、芳烷基酚、腰果酚、辛基酚、双酚A、二甲酚中的至少一种；所述保温反应的温度T1为50℃至70℃、时间t1为2h至7h；所述乳化剂与所述酚类化合物的质量比为(0.08至0.13):1；所述升温反应的温度T2为80℃至120℃、时间t2为1h至5h；
    (2)将所述多孔碳前驱体在惰性气氛下进行碳化处理，然后在含第一化合物的气氛中进行活化处理得到多孔碳基体，所述第一化合物包括二氧化碳或水蒸气；
    其中，所述碳化处理的温度T3为450℃至700℃、时间t3为1h至4h；所述含第一化合物气氛中第一化合物气体的流速V1为1L/min至4L/min，所述活化处理的温度T4为750℃至 1000℃、时间t4为6h至20h；
    (3)将所述多孔碳基体在惰性气氛下进行预处理后在含硅烷气氛下进行处理，然后升温进行保温处理后在含第二化合物的气氛中进行处理得到所述硅碳材料，第二化合物包括乙炔、丙烯或甲苯；
    其中，所述预处理的温度T5为420℃至550℃、时间t5为1h至3h；所述含硅烷气氛包括甲硅烷、乙硅烷、丙硅烷、苯基硅烷、甲苯基硅烷中的至少一种，所述含硅烷气氛中硅烷气体的流速V2为1L/min至3L/min、通气时长t6为220min至480min；保温处理的温度T7为450℃至600℃、时间t7为0.5h至2h；所述含第二化合物的气氛中第二化合物的流速V3为3L/min至10L/min、通气时长t8为160min至400min。
  10. 一种电子装置，其包括权利要求1至8中任一项所述的二次电池或权利要求9中所述的制备方法制得的二次电池。
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