WO2024082292A1 - 硅掺杂石墨烯的负极活性材料、制备方法、二次电池和用电装置 - Google Patents

硅掺杂石墨烯的负极活性材料、制备方法、二次电池和用电装置 Download PDF

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WO2024082292A1
WO2024082292A1 PCT/CN2022/126798 CN2022126798W WO2024082292A1 WO 2024082292 A1 WO2024082292 A1 WO 2024082292A1 CN 2022126798 W CN2022126798 W CN 2022126798W WO 2024082292 A1 WO2024082292 A1 WO 2024082292A1
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negative electrode
electrode active
active material
silicon
graphene
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PCT/CN2022/126798
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English (en)
French (fr)
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周广鹏
甄晓枫
张海明
王邦勇
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宁德时代新能源科技股份有限公司
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Priority to PCT/CN2022/126798 priority Critical patent/WO2024082292A1/zh
Publication of WO2024082292A1 publication Critical patent/WO2024082292A1/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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids

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  • the present application relates to the technical field of lithium batteries, and in particular to a negative electrode active material of silicon-doped graphene, a preparation method, a secondary battery and an electrical device.
  • lithium-ion batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields.
  • lithium-ion batteries have made great progress, higher requirements have been put forward for their energy density, cycle performance and safety performance.
  • Graphene is one of the commonly used negative electrode active materials for lithium-ion batteries.
  • graphene as a negative electrode material for lithium-ion batteries can effectively increase the specific capacity of the corresponding battery, enhance the conductive contact between the electrode and the electrolyte, and improve its charge/discharge rate performance.
  • the flexible single-atom-layer two-dimensional structure of graphene can also effectively inhibit the expansion and pulverization of the material caused by the volume change of the electrode material during the charge and discharge process, thereby improving the cycle stability of the battery.
  • graphene materials have a very high lithium ion diffusion rate, they are prone to stacking during the synthesis process, which causes the graphene materials to fail to perform a good fast lithium insertion function and only serve as a conductive network and a matrix for fixing materials, reducing the overall capacity and fast charging performance of the active material. Therefore, the existing coated or doped graphene negative electrode active materials still need to be improved.
  • the present application is made in view of the above-mentioned problems, and its purpose is to provide a silicon-doped graphene negative electrode active material, which comprises graphene and a silicon-containing material arranged inside the graphene, wherein the volume of the micropores and mesopores thereof is increased, so that the interlayer spacing of the graphene structure is increased, and the lithium insertion channel inside the negative electrode active material is improved, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the first aspect of the present application provides a silicon-doped graphene negative electrode active material, which comprises graphene and a silicon-containing material arranged inside the graphene, wherein the negative electrode active material comprises pores, wherein the volume of micropores with a pore diameter of less than 2 nm is 0.1-0.80 cm 3 /g, and the volume of mesopores with a pore diameter in the range of 2 to 50 nm is 0.12-0.45 cm 3 /g.
  • the negative electrode active material of the present application includes graphene and a silicon-containing material arranged inside the graphene, so that the volume of its micropores and mesopores is increased, the interlayer spacing of the graphene structure is increased, and the lithium insertion channel inside the negative electrode active material is improved, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the volume ratio of the micropores to the mesopores is 0.3-4: 1.
  • the volume ratio of the micropores to the mesopores is 0.3-4: 1.
  • the volume of macropores with a pore size greater than 50 nm is 0.005-0.20 cm 3 /g.
  • the volume of macropores with a pore size greater than 50 nm is 0.005-0.20 cm 3 /g.
  • the volume ratio of the micropores, mesopores and macropores is (1-10): (0.5-5): 1.
  • the volume ratio of the micropores, mesopores and macropores is further increased, so that the corresponding battery has good fast charging capability and cycle performance.
  • the specific surface area of the negative electrode active material is 10-50 m 2 /g.
  • the gram capacity of the negative electrode active material is further increased, so that the corresponding battery has good fast charging capability and cycle performance.
  • the silicon-containing material is an inorganic particle with an average volume particle size of 100 to 300 nm.
  • the gram capacity of the negative electrode active material is further increased through the parameters of the silicon-containing material, so that the corresponding battery has good fast charging capability and cycle performance.
  • the silicon-containing material is selected from elemental silicon, silicon oxide, silicate, silicon-carbon material and a combination thereof.
  • the gram capacity of the negative electrode active material is further increased by the type of the silicon-containing material, so that the corresponding battery has good fast charging capability and cycle performance.
  • the content of the silicon-containing material is 0.3%-5%, based on the total weight of the negative electrode active material.
  • the content of the silicon-containing material further increases the gram capacity of the negative electrode active material, so that the corresponding battery has good fast charging capability and cycle performance.
  • the graphitization degree of the graphene is 90%-98%.
  • the gram capacity of the negative electrode active material is further increased by the graphitization degree of the graphene, so that the corresponding battery has good fast charging capability and cycle performance.
  • the second aspect of the present application also provides a method for preparing a negative electrode active material, which comprises
  • step (3) drying the product of step (2) to obtain a solid
  • step (3) (4) reducing the solid obtained in step (3) to obtain the negative electrode active material
  • the negative electrode active material comprises graphene and silicon doped inside the graphene, wherein the negative electrode active material comprises pores, wherein the volume of micropores with a pore size of less than 2 nm is 0.1-0.80 cm 3 /g, and the volume of mesopores with a pore size in the range of 2-50 nm is 0.12-0.45 cm 3 /g.
  • the method of the present application is simple to operate and low in cost, and the prepared negative electrode active material contains micropores and mesopores with increased volume, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the solvent used in the graphene oxide solution is water.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • step (2) it is characterized in that the mixing time in step (2) is 30-60 minutes.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • step (4) it is characterized in that in step (4), the reduction is carried out at a temperature of 300-600° C.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • step (4) is carried out in an inert atmosphere for 8 hours to 20 hours.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • a third aspect of the present application provides a secondary battery, characterized in that:
  • the fourth aspect of the present application provides an electrical device, characterized in that it includes the secondary battery described in the third aspect of the present application.
  • the negative electrode active material of the present application contains micropores and mesopores with increased volume, and its specific surface area is increased, so that the interlayer spacing of the graphene structure is increased, and the lithium insertion channel inside the negative electrode active material is improved, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance; and its preparation method is simple to operate, low cost, and easy to scale production.
  • FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.
  • FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .
  • FIG. 3 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.
  • Secondary battery 51. Casing; 52. Electrode assembly; 53. Cover plate; 6. Electrical device.
  • range disclosed in the present application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range.
  • the range defined in this way can be inclusive or exclusive of end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 60-120 and 80-110 is listed for a specific parameter, it is understood that the range of 60-110 and 80-120 is also expected.
  • the numerical range "a-b" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers.
  • the numerical range "0-5" represents that all real numbers between "0-5" have been fully listed herein, and "0-5" is just the abbreviation of these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may also include step (c), which means that step (c) can be added to the method in any order.
  • the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the “include” and “comprising” mentioned in this application represent open-ended or closed-ended expressions.
  • the “include” and “comprising” may represent that other components not listed may also be included or only the listed components may be included or only the listed components may be included.
  • the term "or” is inclusive.
  • the phrase “A or B” means “A, B, or both A and B”. More specifically, any of the following conditions satisfies the condition "A or B”: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • graphene as a negative electrode material for lithium-ion batteries can effectively improve the specific capacity of the corresponding battery, enhance the conductive contact between the electrode and the electrolyte, and improve its charge/discharge rate performance.
  • the flexible single-atom-layer two-dimensional structure of graphene can also effectively inhibit the expansion and pulverization of the material caused by the volume change of the electrode material during the charge and discharge process, thereby improving the cycle stability of the battery.
  • graphene materials have a very high lithium ion diffusion rate
  • graphene materials are prone to stacking during the synthesis process, resulting in the graphene materials being unable to perform a good rapid lithium insertion function, and only serving as a conductive network and a matrix for fixing materials, which reduces the overall capacity and fast charging performance of the active material.
  • Improving the rate performance and cycle performance of materials by means of coating or doping is currently a relatively effective means, but the existing methods will lead to varying degrees of damage to the performance of lithium-ion batteries, for example, the gram capacity of lithium-ion batteries is reduced, the fast charging performance is insufficient, etc. Therefore, the existing coated or doped positive electrode material graphene negative electrode active material still needs to be improved.
  • the negative electrode active material of the first aspect of the present invention includes graphene and a silicon-containing material disposed inside the graphene, so that the volume of its micropores and mesopores is increased, and its specific surface area is increased, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the first aspect of the present application provides a negative electrode active material, comprising graphene and a silicon-containing material disposed inside the graphene, wherein the negative electrode active material comprises pores, wherein the volume of micropores with a pore diameter of less than 2 nm is 0.1-0.80 cm 3 /g, optionally 0.4-0.7 cm 3 /g, and further optionally 0.55-0.62 cm 3 /g, and the volume of mesopores with a pore diameter in the range of 2 to 50 nm is 0.12-0.45 cm 3 /g, optionally 0.25-0.45 cm 3 /g, and further optionally 0.35-0.40 cm 3 /g.
  • the negative electrode active material of the present application includes graphene and a silicon-containing material arranged inside the graphene, and the silicon-containing material increases the interlayer spacing of the graphene structure. Therefore, the volume of the micropores and mesopores of the negative electrode active material increases, which can construct a fast lithium ion channel, improve the lithium insertion channel inside the negative electrode active material, and stabilize the structure of the negative electrode active material. At the same time, the gram capacity of the negative electrode active material is increased, so that the corresponding battery has good fast charging capability and cycle performance.
  • the volume of each type of pore refers to the volume of each type of pore in each gram of the negative electrode active material, with the unit of cm 3 /g; it is measured according to GB/T 21650.2-2008.
  • the volume ratio of the micropores to the mesopores is 0.3-4: 1, optionally 1.1-1.9: 1, and further optionally 1.4-1.6: 1.
  • the volume ratio of the micropores to the mesopores is 0.3-4: 1, optionally 1.1-1.9: 1, and further optionally 1.4-1.6: 1.
  • the sum of the volumes of the micropores and the mesopores is 0.7-0.98 cm 3 /g, optionally 0.85-0.96 cm 3 /g, and further optionally 0.92-0.96 cm 3 /g.
  • the volume of macropores with a pore size greater than 50 nm is 0.005-0.20 cm 3 /g, and optionally 0.09-0.16 cm 3 /g.
  • the volume of macropores with a pore size greater than 50 nm is 0.005-0.20 cm 3 /g, and optionally 0.09-0.16 cm 3 /g.
  • the volume ratio of the micropores, mesopores and macropores is (1-10): (0.5-5): 1, and optionally (3-5): (1.5-2.5): 1.
  • the volume ratio of the micropores, mesopores and macropores is 1-10: (0.5-5): 1, and optionally (3-5): (1.5-2.5): 1.
  • the specific surface area of the negative electrode active material is 10-50m 2 /g, optionally 20-30m 2 /g, and further optionally 24-26m 2 /g; measured according to the gas adsorption BET method of GB/T 19587-2004.
  • the specific surface area of the negative electrode active material is 10-50m 2 /g, optionally 20-30m 2 /g, and further optionally 24-26m 2 /g; measured according to the gas adsorption BET method of GB/T 19587-2004.
  • the silicon-containing material is an inorganic particle with an average volume particle size of 100 to 300 nm.
  • the gram capacity of the negative electrode active material is further increased through the parameters of the silicon-containing material, so that the corresponding battery has good fast charging capability and cycle performance.
  • the particle size distribution of the silicon-containing material further satisfies:
  • D max is the maximum particle size of the particles
  • D v99 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 99%
  • D v90 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 90%
  • D v10 is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 10%
  • the average volume particle size is the particle size corresponding to when the volume cumulative distribution percentage of the sample reaches 50%; it is measured using a laser particle size analyzer, such as the Mastersizer 3000 laser particle size analyzer of Malvern Instruments Ltd., UK.
  • the silicon-containing material is selected from elemental silicon, silicon oxide, silicate, silicon-carbon material and combinations thereof.
  • the gram capacity of the negative electrode active material is further increased by the type of the silicon-containing material, so that the corresponding battery has good fast charging capability and cycle performance.
  • the elemental silicon includes crystalline silicon or amorphous silicon.
  • the silicon oxide includes silicon dioxide, silicon monoxide, silicon peroxide, etc.
  • the silicate includes alkali metal salts and alkaline earth metal salts of silicic acid, etc.
  • the silicon-containing material is selected from elemental silicon, silicon oxide and a combination thereof; can be selected from elemental silicon, silicon dioxide, silicon monoxide and a combination thereof, and can further be selected from elemental silicon.
  • the content of the silicon-containing material is 0.3%-5%, optionally 0.5-2.5%, and further optionally 1.8-2.3%, based on the total weight of the negative electrode active material.
  • the content of the silicon-containing material further increases the gram capacity of the negative electrode active material, so that the corresponding battery has good fast charging capability and cycle performance.
  • the graphitization degree of the graphene is 90%-98%, optionally 93-96%.
  • the gram capacity of the negative electrode active material is further increased by the graphitization degree of the graphene, so that the corresponding battery has good fast charging capability and cycle performance.
  • the graphitization degree is determined according to the "Method for Determining Lattice Parameters of Artificial Graphite" in the "General Rules for X-ray Diffraction Analysis".
  • the average volume particle size D v50 of the negative electrode active material is 10 to 30 um, and may be 15 to 25 um, and the testing method thereof is as described above.
  • the gram capacity of the negative electrode active material is ⁇ 500 mAh/g, and can be 550-600 mAh/g.
  • the second aspect of the present application also provides a method for preparing a negative electrode active material, which comprises
  • step (3) drying the product of step (2) to obtain a solid
  • step (3) (4) reducing the solid obtained in step (3) to obtain the negative electrode active material
  • the negative electrode active material comprises graphene and silicon doped inside the graphene, wherein the negative electrode active material comprises pores, wherein the volume of micropores with a pore size of less than 2 nm is 0.1-0.80 cm 3 /g, and the volume of mesopores with a pore size in the range of 2-50 nm is 0.12-0.45 cm 3 /g.
  • the preparation method of the present application is simple to operate, low in cost, and easy to mass produce.
  • the prepared negative electrode active material contains micropores and mesopores with increased volume, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the solvent used in the graphene oxide solution is water.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the graphene used in step (1) can be a commercially available product, or can be prepared by methods known in the art.
  • the graphene solution can be provided in the following manner:
  • the silicon-containing raw material is elemental silicon, silicon oxide, silicate, silicon-carbon material and combinations thereof, and can be silicon elemental, silicon oxide or silicon sulphide oxide, and can be silicon elemental.
  • the mixing time in step (2) is 30-60 min.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • step (2) when the solvent used in the graphene oxide solution is water, the temperature used is 70-100°C, optionally 80-100°C.
  • step (3) comprises filtering the product of step (2), i.e. the above solution, washing with water until neutral, and drying in a drying oven at -0.1 MPa for 3-9 hours to obtain a solid.
  • the reduction in step (4) is performed at a temperature of 300-600° C.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the reduction in step (4) is carried out in an inert atmosphere for 8 to 20 hours.
  • a negative electrode active material containing micropores and mesopores with increased volume is prepared, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the inert atmosphere includes at least one of nitrogen, helium, and argon.
  • step (4) includes moving the solid from step (3) into a tubular furnace and heating it to a temperature of 300-600° C. in an inert atmosphere for 8 hours to 20 hours, optionally 10-14 hours; after natural cooling, taking out the calcined material and grinding it to obtain the negative electrode active material.
  • the negative electrode active material has all the technical features of the negative electrode active material described in the first aspect of the present application.
  • a third aspect of the present application provides a secondary battery, characterized in that:
  • the maximum current rate of the secondary battery during charging from 10% state of charge (SOC) to 90% SOC (10-90% SOC) at room temperature is ⁇ 4C, where C represents the current rate, and 1C is the current size that can charge the battery from 0% SOC to 100% SOC in 1 hour.
  • the fourth aspect of the present application provides an electrical device, characterized in that it includes the secondary battery described in the third aspect of the present application.
  • a secondary battery is provided.
  • a secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator.
  • active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet.
  • the electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet.
  • the separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material commonly used in the art.
  • the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.
  • the positive electrode current collector may be a metal foil or a composite current collector.
  • aluminum foil may be used as the metal foil.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer.
  • the composite current collector may be formed by forming a metal material on a polymer material substrate.
  • the metal material includes but is not limited to aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.
  • Polymer material substrate such as substrates of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.
  • the positive electrode active material may include a positive electrode active material for a battery known in the art.
  • the positive electrode active material may include at least one of the following materials: an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.
  • the present application is not limited to these materials, and other conventional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more.
  • lithium transition metal oxides may include, but are not limited to , lithium cobalt oxide (such as LiCoO2 ), lithium nickel oxide (such as LiNiO2 ), lithium manganese oxide (such as LiMnO2 , LiMn2O4 ), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi1 / 3Co1 / 3Mn1 / 3O2 (also referred to as NCM333 ), LiNi0.5Co0.2Mn0.3O2 (also referred to as NCM523 ) , LiNi0.5Co0.25Mn0.25O2 (also referred to as NCM211 ) , LiNi0.6Co0.2Mn0.2O2 (also referred to as NCM622 ), LiNi0.8Co0.1Mn0.1O2 (also referred to as NCM811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05
  • lithium-containing phosphates with an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO 4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO 4 ), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.
  • the weight ratio of the positive electrode active material in the positive electrode film layer is 80-100% by weight, based on the total weight of the positive electrode film layer.
  • the positive electrode film layer may also optionally include a binder.
  • the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylate resin.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • the weight ratio of the binder in the positive electrode film layer is 0-20% by weight, based on the total weight of the positive electrode film layer.
  • the positive electrode film layer may further include a conductive agent.
  • the conductive agent may include at least one of superconducting carbon, carbon black (e.g., acetylene black, Ketjen black), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the weight ratio of the conductive agent in the positive electrode film layer is 0-20% by weight, based on the total weight of the positive electrode film layer.
  • the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry, wherein the positive electrode slurry has a solid content of 40-80wt%, and the viscosity at room temperature is adjusted to 5000-25000mPa ⁇ s, the positive electrode slurry is coated on the surface of the positive electrode collector, and after drying, it is cold-pressed by a cold rolling mill to form a positive electrode sheet; the positive electrode powder coating unit area density is 150-350g/m 2 , and the positive electrode sheet compaction density is 3.0-3.6g/cm 3 , and can be optionally 3.3-3.5g/cm 3.
  • the compaction density is calculated by the formula:
  • Compacted density coating surface density/(thickness of the electrode after extrusion - thickness of the current collector).
  • the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer arranged on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes the negative electrode active material described in one aspect of the present application or prepared according to the method of the second aspect of the present application.
  • the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.
  • the negative electrode current collector may be a metal foil or a composite current collector.
  • copper foil may be used as the metal foil.
  • the composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material substrate.
  • the composite current collector may be formed by forming a metal material on a polymer material substrate.
  • the metal material includes but is not limited to copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.
  • the polymer material substrate includes but is not limited to polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) and other substrates.
  • the negative electrode active material may also include other negative electrode active materials for batteries known in the art.
  • other negative electrode active materials may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc.
  • the silicon-based material may be selected from at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys.
  • the tin-based material may be selected from at least one of elemental tin, tin oxide compounds, and tin alloys.
  • the present application is not limited to these other materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These other negative electrode active materials may be used alone or in combination of two or more.
  • the weight ratio of the negative electrode active material in the negative electrode film layer is 70-100 weight %, based on the total weight of the negative electrode film layer.
  • the negative electrode film layer may further include a binder.
  • the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • SBR styrene-butadiene rubber
  • PAA polyacrylic acid
  • PAAS sodium polyacrylate
  • PAM polyacrylamide
  • PVA polyvinyl alcohol
  • SA sodium alginate
  • PMAA polymethacrylic acid
  • CMCS carboxymethyl chitosan
  • the negative electrode film layer may further include a conductive agent.
  • the conductive agent may be selected from at least one of superconducting carbon, carbon black (e.g., acetylene black, Ketjen black), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • the weight ratio of the conductive agent in the negative electrode film layer is 0-20% by weight, based on the total weight of the negative electrode film layer.
  • the negative electrode film layer may further include other additives, such as a thickener (such as sodium carboxymethyl cellulose (CMC-Na)), etc.
  • a thickener such as sodium carboxymethyl cellulose (CMC-Na)
  • the weight ratio of the other additives in the negative electrode film layer is 0-15% by weight, based on the total weight of the negative electrode film layer.
  • the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (such as deionized water) to form a negative electrode slurry, wherein the solid content of the negative electrode slurry is 30-70wt%, and the viscosity at room temperature is adjusted to 2000-10000mPa ⁇ s; the obtained negative electrode slurry is coated on the negative electrode collector, and after a drying process, cold pressing such as rolling, a negative electrode sheet is obtained.
  • the negative electrode powder coating unit area density is 75-220g/ m2
  • the negative electrode sheet compaction density is 1.2-2.0g/ m3 .
  • the electrolyte plays the role of conducting ions between the positive electrode and the negative electrode.
  • the present application has no specific restrictions on the type of electrolyte, which can be selected according to needs.
  • the electrolyte can be liquid, gel or all-solid.
  • the electrolyte is an electrolyte solution, which includes an electrolyte salt and a solvent.
  • the electrolyte salt may be selected from one or more of lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium perchlorate (LiClO 4 ), lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO 2 F 2 ), lithium difluorobis(oxalatophosphate) (LiDFOP) and lithium tetrafluorooxalatophosphate (LiTFOP).
  • concentration of the electrolyte salt is generally 0.5-5
  • the solvent can be selected from one or more of fluoroethylene carbonate (FEC), ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS) and diethyl sulfone (FEC),
  • the electrolyte may further include additives, such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • additives such as negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc.
  • the secondary battery further includes a separator.
  • the present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.
  • the material of the isolation membrane can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride.
  • the isolation membrane can be a single-layer film or a multi-layer composite film, without particular limitation.
  • the materials of each layer can be the same or different, without particular limitation.
  • the isolation film has a thickness of 6-40 ⁇ m, and optionally 12-20 ⁇ m.
  • the positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly by a winding process or a lamination process.
  • the secondary battery may include an outer package that can be used to encapsulate the electrode assembly and the electrolyte.
  • the outer packaging of the secondary battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the secondary battery may also be a soft package, such as a bag-type soft package.
  • the material of the soft package may be plastic, and examples of the plastic include polypropylene, polybutylene terephthalate, and polybutylene succinate.
  • FIG1 is a secondary battery 5 of a square structure as an example.
  • the outer package may include a shell 51 and a cover plate 53.
  • the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate are enclosed to form a receiving cavity.
  • the shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process or a lamination process.
  • the electrode assembly 52 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 52.
  • the number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.
  • secondary batteries may be assembled into a battery module.
  • the number of secondary batteries contained in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.
  • the plurality of secondary batteries 5 may be arranged in sequence along the length direction of the battery module. Of course, they may also be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by fasteners.
  • the battery module may further include a housing having a housing space, and the plurality of secondary batteries 5 are housed in the housing space.
  • the battery modules described above may also be assembled into a battery pack.
  • the battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery pack.
  • the battery pack may include a battery box and a plurality of battery modules disposed in the battery box.
  • the battery box includes an upper box body and a lower box body, and the upper box body can be covered on the lower box body to form a closed space for accommodating the battery modules.
  • the plurality of battery modules 4 can be arranged in the battery box in any manner.
  • the present application also provides an electrical device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application.
  • the secondary battery, battery module, or battery pack can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device.
  • the electrical device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but are not limited to these.
  • a secondary battery, a battery module or a battery pack may be selected according to its usage requirements.
  • FIG3 is an example of an electric device.
  • the electric device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or a battery module may be used.
  • the device may be a mobile phone, a tablet computer, a notebook computer, etc.
  • the device is usually required to be thin and light, and a secondary battery may be used as a power source.
  • step (2) the amount of silicon powder used was 0.5 g.
  • step (2) the amount of silicon powder used was 0.75 g.
  • step (2) the amount of silicon powder used was 1.25 g.
  • the calcined material is dispersed in deionized water, and then 1 g of Si powder is added and stirred at 100°C for 30 min to obtain a mixed solution; then, the solution is filtered using a vacuum filter and dried using a vacuum dryer to obtain the negative electrode active material.
  • the positive electrode active material lithium nickel cobalt manganese oxide, conductive carbon black SP and binder PVDF were dispersed in a solvent NMP at a weight ratio of 98:1:1 and mixed evenly to obtain a positive electrode slurry; the positive electrode slurry was evenly coated on a positive electrode current collector aluminum foil, and after drying and cold pressing, a positive electrode sheet was obtained, and the coating amount per unit area was 0.27g/ 1540.25mm2 .
  • the negative electrode active material of Preparation Example 1 thickener sodium carboxymethyl cellulose, binder styrene butadiene rubber, and conductive agent acetylene black were mixed in a mass ratio of 97:1:1:1, and deionized water was added to obtain a negative electrode slurry under the action of a vacuum mixer; the negative electrode slurry was evenly coated on a copper foil; the copper foil was dried at room temperature and then transferred to a 120°C oven for drying for 1 hour, and then supercooled pressed and cut to obtain a negative electrode sheet, and the coating amount per unit area was 0.17g/ 1540.25mm2 .
  • a 12 ⁇ m thick polypropylene isolation film was selected.
  • the organic solvent is a mixed solution containing ethylene carbonate (EC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC), wherein the volume ratio of EC, EMC and DEC is 20:20:60.
  • EC ethylene carbonate
  • EMC ethyl methyl carbonate
  • DEC diethyl carbonate
  • the volume ratio of EC, EMC and DEC is 20:20:60.
  • argon atmosphere glove box with a water content of ⁇ 10ppm fully dried lithium salt LiPF6 is dissolved in the organic solvent and mixed evenly to obtain an electrolyte.
  • the concentration of the lithium salt is 1 mol/L.
  • the positive electrode sheet, isolation film, and negative electrode sheet are stacked in order, so that the isolation film is placed between the positive and negative electrode sheets to play an isolating role. Then, they are wound into a square bare battery cell, loaded with aluminum-plastic film, and then baked at 80°C to remove water, and 10g of the corresponding non-aqueous electrolyte is injected and sealed. After standing, hot and cold pressing, formation, clamping, capacity division and other processes, a finished battery with a capacity of 4000mAh is obtained.
  • the secondary batteries of Examples 2 to 12 and the secondary batteries of Comparative Examples 1 to 3 were prepared in a similar manner to the secondary battery of Example 1, but the negative electrode active materials of the corresponding preparation examples were used.
  • the battery capacity test is to place the lithium-ion battery at a constant temperature of 25°C for 2 hours, then charge it to 4.35V at 1/3C at 2.5V ⁇ 4.35V, then charge it at a constant voltage at 4.35V to a current ⁇ 0.05mA, let it stand for 5 minutes, and then discharge it to 2.5V at 1C, and record the capacity C of the battery.
  • the gram capacity the capacity C of the battery (mAh)/the mass of the positive electrode active material (g).
  • the charging rates were 1C, 2C, and 3C, respectively, from 0% SOC to 100% SOC, and then discharged at 0.33C to 0% SOC, and the discharge capacity at different charging rates was compared.
  • the battery was charged from 10% SOC to 90% SOC at room temperature.
  • a current test was performed within the SOC range to test the maximum current rate when the anode reached 0 potential.
  • the batteries of the embodiments and comparative examples were prepared according to the above method, and various performance parameters were measured. The results are shown in Table 2 below.
  • the volume of micropores and mesopores in the negative electrode active material of the present application is increased, which improves the lithium insertion channel inside the negative electrode active material, thereby increasing its gram capacity, so that the corresponding battery has good fast charging capability and cycle performance.
  • the gram capacity of the present application is greater than 500mAh/g, and the maximum current rate of 10-90% SOC is greater than 4C.

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Abstract

本申请涉及一种负极活性材料，其包含石墨烯和设置在所述石墨烯内部的含硅材料，其中所述负极活性材料包含孔，其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g；以及涉及其制备方法、二次电池和用电装置。所述负极活性材料的微孔和介孔的体积增大，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。

Description

硅掺杂石墨烯的负极活性材料、制备方法、二次电池和用电装置 技术领域
本申请涉及锂电池技术领域，尤其涉及一种硅掺杂石墨烯的负极活性材料、制备方法、二次电池和用电装置。
背景技术
近年来，随着锂离子电池的应用范围越来越广泛，锂离子电池广泛应用于水力、火力、风力和太阳能电站等储能电源系统，以及电动工具、电动自行车、电动摩托车、电动汽车、军事装备、航空航天等多个领域。由于锂离子电池取得了极大的发展，因此对其能量密度、循环性能和安全性能等也提出了更高的要求。石墨烯是锂离子电池的常用的负极活性材料之一。
与传统锂离子电池负极材料相比较，石墨烯作为锂离子电池负极材料时，可有效提高相应电池的比容量，增强电极和电解液之间的导电接触，改善其充/放电倍率性能。同时，石墨烯柔韧的单原子层二维结构也可有效抑制电极材料在充放电过程中发生体积变化引起的材料膨胀、粉化等，从而提高电池的循环稳定性。
石墨烯材料虽然具有非常高的锂离子扩散速率，但是石墨烯材料在合成过程中易发生堆叠，造成石墨烯材料不能发挥很好的快速嵌锂功能，仅作为导电网络和固定材料的基体，降低了活性材料整体的容量和快充性能。因此，现有的被包覆或掺杂的石墨烯负极活性材料仍有待改进。
发明内容
本申请是鉴于上述课题而进行的，其目的在于，提供一种硅掺杂石墨烯的负极活性材料，其包含石墨烯和设置在所述石墨烯内部的含硅材料，其微孔和介孔的体积增大，使得石墨烯结构层间距增大，改善了负极活性材料内部的嵌锂通道，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
为了达到上述目的，本申请的第一方面提供了一种硅掺杂石墨烯的负极活性材料，其包含石墨烯和设置在所述石墨烯内部的含硅材料，其中所述负极活性材料包含孔， 其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g。
由此，本申请的负极活性材料包含石墨烯和设置在所述石墨烯内部的含硅材料，使得其微孔和介孔的体积增大，使得石墨烯结构层间距增大，改善了负极活性材料内部的嵌锂通道，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述微孔与介孔的体积的比值为0.3-4：1。由此，通过限定微孔和介孔的体积比，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，孔径大于50nm的大孔的体积为0.005～0.20cm 3/g。由此，通过限定大孔的体积，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述微孔、介孔和大孔的体积比为(1-10)：(0.5-5)：1。由此，通过限定微孔、介孔和大孔的体积比，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述负极活性材料的比表面积为10-50m 2/g。由此，通过限定所述负极活性材料的比表面积，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述含硅材料为平均体积粒径为100～300nm的无机颗粒。由此，通过所述含硅材料的参数，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述含硅材料选自单质硅、硅的氧化物、硅酸盐、硅碳材料和其组合。由此，通过所述含硅材料的种类，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述含硅材料的含量为0.3％-5％，基于所述负极活性材料的总重量计。由此，通过所述含硅材料的含量，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，所述石墨烯的石墨化程度为90％-98％。由此，通过所述石墨烯的石墨化程度，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良 好的快充能力和循环性能。
本申请的第二方面还提供一种制备负极活性材料的方法，其包括
(1)提供氧化石墨烯溶液；
(2)在比氧化石墨烯溶液中使用的溶剂的沸点低30℃的温度至氧化石墨烯溶液中使用的溶剂的沸点的温度下，将含硅原料加入所述氧化石墨烯溶液中混合；
(3)将步骤(2)的产物干燥，得到固体；
(4)将步骤(3)的固体还原，制得所述负极活性材料；
其中所述负极活性材料包含石墨烯和掺杂在所述石墨烯内部的硅，其中所述负极活性材料包含孔，其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g。
由此，本申请的方法操作简单，成本低，并且制备的负极活性材料包含体积增大的微孔和介孔，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，在步骤(1)中，所述氧化石墨烯溶液中使用的溶剂为水。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，其特征在于，在步骤(2)中混合时间为30-60min。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，其特征在于，在步骤(4)中所述还原在300-600℃的温度下进行。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在任意实施方式中，其特征在于，在步骤(4)中所述还原在惰性气氛中进行8小时-20小时。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
本申请的第三方面提供一种二次电池，其特征在于，
包括本申请第一方面所述的负极活性材料或根据本申请第二方面所述的方法制备的负极活性材料。
本申请的第四方面提供一种用电装置，其特征在于，包括本申请的第三方面所述 的二次电池。
本申请的负极活性材料包含体积增大的微孔和介孔，并且其比表面积增大，使得石墨烯结构层间距增大，改善了负极活性材料内部的嵌锂通道，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能；并且其制备方法操作简单，成本低廉，易于规模化生产。
附图说明
图1是本申请一实施方式的二次电池的示意图。
图2是图1所示的本申请一实施方式的二次电池的分解图。
图3是本申请一实施方式的二次电池用作电源的用电装置的示意图。
附图标记说明：
5、二次电池；51、壳体；52、电极组件；53、盖板；6、用电装置。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的硅掺杂石墨烯的负极活性材料、制备方法、二次电池和用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60-120和80-110的范围，理解为60-110和80-120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1-3、1-4、1-5、2-3、2-4和2-5。在本申请中，除非有其他说明，数值范围“a-b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0-5”表示本文中已经全部列出了“0-5”之间的全部实数，“0-5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、 10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，可选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
目前，与传统锂离子电池负极材料相比较，石墨烯作为锂离子电池负极材料时，可有效提高相应电池的比容量，增强电极和电解液之间的导电接触，改善其充/放电倍率性能。同时，石墨烯柔韧的单原子层二维结构也可有效抑制电极材料在充放电过程中发生体积变化引起的材料膨胀、粉化等，从而提高电池的循环稳定性。
石墨烯材料虽然具有非常高的锂离子扩散速率，但是石墨烯材料在合成过程中易发生堆叠，造成石墨烯材料不能发挥很好的快速嵌锂功能，仅作为导电网络和固定材料的基体，降低了活性材料整体的容量和快充性能。通过包覆或掺杂等手段来改善材料的倍率性能和循环性能等是目前比较有效的手段，然而现有的方法均会导致对锂离子电池性能不同程度的破坏，例如，锂离子电池的克容量降低、快充性能不足等。因此，现有的被包覆或掺杂的正极材料石墨烯负极活性材料仍有待改进。发明人研究发现本发明的第一方面的负极活性材料通过包含石墨烯和设置在所述石墨烯内部的含硅材料，使得其微孔和介孔的体积增大，并且其比表面积增大，从而增大了其克容量， 使得相应的电池具有良好的快充能力和循环性能。
负极活性材料
在一些实施方式中，本申请的第一方面提供了一种负极活性材料，其包含石墨烯和设置在所述石墨烯内部的含硅材料，其中所述负极活性材料包含孔，其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，可选0.4-0.7cm 3/g，进一步可选为0.55-0.62cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g，可选为0.25-0.45cm 3/g，进一步可选为0.35-0.40cm 3/g。
由此，本申请的负极活性材料包含石墨烯和设置在所述石墨烯内部的含硅材料，所述含硅材料使得石墨烯结构层间距增大，因此，所述负极活性材料的微孔和介孔的体积增大，这能够构筑快速的锂离子通道，改善了负极活性材料内部的嵌锂通道并且所述负极活性材料结构稳定，同时增大了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在本申请中，各类孔的体积意指每克所述负极活性材料中各类孔所具有的体积，单位为cm 3/g；其根据GB/T 21650.2-2008测量。
在一些实施方式中，所述微孔与介孔的体积的比值为0.3-4：1，可选1.1-1.9:1，进一步可选为1.4-1.6:1。由此，通过限定微孔和介孔的体积比，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述微孔与介孔的体积的之和为0.7-0.98cm 3/g，可选0.85-0.96cm 3/g，进一步可选为0.92-0.96cm 3/g。
在一些实施方式中，孔径大于50nm的大孔的体积为0.005～0.20cm 3/g，可选0.09-0.16cm 3/g。由此，通过限定大孔的体积，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述微孔、介孔和大孔的体积比为(1-10)：(0.5-5)：1，可选(3-5)：(1.5-2.5)：1。由此，通过限定微孔、介孔和大孔的体积比，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述负极活性材料的比表面积为10-50m 2/g，可选为20-30m 2/g，进一步可选为24-26m 2/g；根据GB/T 19587-2004气体吸附BET法测定。由此，通过限定所述负极活性材料的比表面积，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述含硅材料为平均体积粒径为100～300nm的无机颗粒。由此，通过所述含硅材料的参数，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述含硅材的颗粒粒度分布还满足：
D max≤1000nm；D v99为600～800nm；D v90为400～600nm；D v10为20～50nm。
D max为颗粒的最大粒径，D v99为样品的体积累计分布百分数达到99％时对应的粒径；D v90为样品的体积累计分布百分数达到90％时对应的粒径；D v10为样品的体积累计分布百分数达到10％时对应的粒径；所述平均体积粒径为样品的体积累计分布百分数达到50％时对应的粒径；其是以采用激光粒度分析仪例如英国马尔文仪器有限公司的Mastersizer 3000型激光粒度分析仪测定。
在一些实施方式中，所述含硅材料选自单质硅、硅的氧化物、硅酸盐、硅碳材料和其组合。由此，通过所述含硅材料的种类，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述单质硅包括晶体硅或无定型硅。所述硅的氧化物包括二氧化硅、氧化亚硅和过氧化硅等。所述硅酸盐包括硅酸的碱金属盐和碱土金属盐等。
在一个可选的实施方式中，所述含硅材料选自单质硅、硅氧化物和其组合；可选选自单质硅、二氧化硅、氧化亚硅和其组合，进一步可选为单质硅。
在一些实施方式中，所述含硅材料的含量为0.3％-5％，可选为0.5-2.5％，进一步可选为1.8-2.3％，基于所述负极活性材料的总重量计。由此，通过所述含硅材料的含量，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述石墨烯的石墨化程度为90％-98％，可选为93-96％。由此，通过所述石墨烯的石墨化程度，进一步提高了所述负极活性材料的克容量，使得相应的电池具有良好的快充能力和循环性能。所述石墨化度根据《X射线衍射分析法通则》中“人造石墨的点阵参数测定方法”进行测定。
在一些实施方式中，所述负极活性材料的平均体积粒径D v50为10～30um，可选15～25um，其测试方式如上所述。
在一些实施方式中，所述负极活性材料的克容量为≥500mAh/g，可选为550-600mAh/g。
本申请的第二方面还提供一种制备负极活性材料的方法，其包括
(1)提供氧化石墨烯溶液；
(2)在比氧化石墨烯溶液中使用的溶剂的沸点低30℃的温度至氧化石墨烯溶液中使用的溶剂的沸点的温度下，将含硅原料加入所述氧化石墨烯溶液中混合；
(3)将步骤(2)的产物干燥，得到固体；
(4)将步骤(3)的固体还原，制得所述负极活性材料；
其中所述负极活性材料包含石墨烯和掺杂在所述石墨烯内部的硅，其中所述负极活性材料包含孔，其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g。
由此，本申请的制备方法操作简单，成本低廉，易于规模化生产，制备的负极活性材料包含体积增大的微孔和介孔，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，在步骤(1)中，所述氧化石墨烯溶液中使用的溶剂为水。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，在步骤(1)中所用的石墨烯可以是市售的商品，也可以通过本领域已知的方法制备。在本申请中所述石墨烯溶液可以以下方式提供：
将10-30g石墨与20-40mL硫酸、1-10g高锰酸钾和1-5g硝酸钠在-10至10温度下混合10-60分钟，然后加入水，加热至80-120℃下混合10-60min，然后，加入5-20ml浓度为30％的双氧水溶液；静置，移走上层液体；加入50-200mL、可选90-110mL水混合均匀，然后将所得的混合物加热至80-120℃混合20-40min，得到氧化石墨烯溶液，备用。
在一些实施方式中，在步骤(2)中，含硅原料为单质硅、硅的氧化物、硅酸盐、硅碳材料和其组合，可选为硅单质、氧化硅或氧化亚硅，可选硅单质。
在一些实施方式中，在步骤(2)中混合时间为30-60min。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，在步骤(2)中，在氧化石墨烯溶液中使用的溶剂为水的情况下，所使用的温度为70-100℃，可选80-100℃。
在一些实施方式中，步骤(3)包括将步骤(2)的产物，即上述溶液，过滤并用水洗涤至中性，放入干燥箱在-0.1MPa下干燥3-9h，得到固体。
在一些实施方式中，在步骤(4)中所述还原在300-600℃的温度下进行。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，在步骤(4)中所述还原在惰性气氛中进行8小时-20小时。由此制备包含体积增大的微孔和介孔的负极活性材料，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能。
在一些实施方式中，所述惰性气氛包括氮气、氦气、氩气中的至少一种。
在一些实施方式中，步骤(4)包括将步骤(3)的固体移至管式炉内加热至300-600℃的温度，在惰性气氛中进行8小时-20小时，可选10-14h；自然冷却后，取出煅烧后的材料，研磨，得到所述负极活性材料。
所述负极活性材料具有本申请的第一方面所述的负极活性材料的所有技术特征。
本申请的第三方面提供一种二次电池，其特征在于，
包括本申请第一方面所述的负极活性材料或根据本申请第二方面所述的方法制备的负极活性材料。
所述二次电池在室温下从10％荷电状态(SOC)充电至90％SOC的过程中(10-90％SOC)的最大电流倍率≥4C，其中C代表代表电流倍率，1C即为1h可以将电池从0％SOC充至100％SOC的电流大小。
本申请的第四方面提供一种用电装置，其特征在于，包括本申请的第三方面所述的二次电池。
以下适当参照附图对本申请的二次电池和用电装置进行说明。
本申请的一个实施方式中，提供一种二次电池。
通常情况下，二次电池包括正极极片、负极极片、电解质和隔离膜。在电池充放电过程中，活性离子在正极极片和负极极片之间往返嵌入和脱出。电解质在正极极片和负极极片之间起到传导离子的作用。隔离膜设置在正极极片和负极极片之间，主要起到防止正负极短路的作用，同时可以使离子通过。
正极极片
正极极片包括正极集流体以及设置在正极集流体至少一个表面的正极膜层，所述 正极膜层包括本领域常用的正极活性材料。
作为示例，正极集流体具有在其自身厚度方向相对的两个表面，正极膜层设置在正极集流体相对的两个表面的其中任意一者或两者上。
在一些实施方式中，所述正极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可采用铝箔。复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料形成在高分子材料基材上而形成。其中，金属材料包括但不限于铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等。高分子材料基材(如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材)
在一些实施方式中，正极活性材料可包含本领域公知的用于电池的正极活性材料。作为示例，正极活性材料可包括以下材料中的至少一种：橄榄石结构的含锂磷酸盐、锂过渡金属氧化物及其各自的改性化合物。但本申请并不限定于这些材料，还可以使用其他可被用作电池正极活性材料的传统材料。这些正极活性材料可以仅单独使用一种，也可以将两种以上组合使用。其中，锂过渡金属氧化物的示例可包括但不限于锂钴氧化物(如LiCoO 2)、锂镍氧化物(如LiNiO 2)、锂锰氧化物(如LiMnO 2、LiMn 2O 4)、锂镍钴氧化物、锂锰钴氧化物、锂镍锰氧化物、锂镍钴锰氧化物(如LiNi 1/3Co 1/3Mn 1/3O 2(也可以简称为NCM 333)、LiNi 0.5Co 0.2Mn 0.3O 2(也可以简称为NCM 523)、LiNi 0.5Co 0.25Mn 0.25O 2(也可以简称为NCM 211)、LiNi 0.6Co 0.2Mn 0.2O 2(也可以简称为NCM 622)、LiNi 0.8Co 0.1Mn 0.1O 2(也可以简称为NCM 811)、锂镍钴铝氧化物(如LiNi 0.85Co 0.15Al 0.05O 2)及其改性化合物等中的至少一种。橄榄石结构的含锂磷酸盐的示例可包括但不限于磷酸铁锂(如LiFePO 4(也可以简称为LFP))、磷酸铁锂与碳的复合材料、磷酸锰锂(如LiMnPO 4)、磷酸锰锂与碳的复合材料、磷酸锰铁锂、磷酸锰铁锂与碳的复合材料中的至少一种。所述正极活性材料在正极膜层中的重量比为80-100重量％，基于正极膜层的总重量计。
在一些实施方式中，正极膜层还可选地包括粘结剂。作为示例，所述粘结剂可以包括聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物及含氟丙烯酸酯树脂中的至少一种。所述粘结剂在正极膜层中的重量比为0-20重量％，基于正极膜层的总重量计。
在一些实施方式中，正极膜层还可选地包括导电剂。作为示例，所述导电剂可以包括超导碳、炭黑(例如乙炔黑、科琴黑)、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在正极膜层中的重量比为0-20重量％，基于正极膜层的总重量计。
在一些实施方式中，可以通过以下方式制备正极极片：将上述用于制备正极极片的组分，例如正极活性材料、导电剂、粘结剂和任意其他的组分分散于溶剂(例如N-甲基吡咯烷酮)中，形成正极浆料，其中所述正极浆料固含量为40-80wt％，室温下的粘度调整到5000-25000mPa·s，将正极浆料涂覆在正极集流体的表面，烘干后经过冷轧机冷压后形成正极极片；正极粉末涂布单位面密度为150-350g/m 2，正极极片压实密度为3.0-3.6g/cm 3，可选为3.3-3.5g/cm 3。所述压实密度的计算公式为
压实密度＝涂布面密度/(挤压后极片厚度-集流体厚度)。
负极极片
负极极片包括负极集流体以及设置在负极集流体至少一个表面上的负极膜层，所述负极膜层包括本申请的一方面所述或者根据本申请的第二方面的方法制备的负极活性材料。
作为示例，负极集流体具有在其自身厚度方向相对的两个表面，负极膜层设置在负极集流体相对的两个表面中的任意一者或两者上。
在一些实施方式中，所述负极集流体可采用金属箔片或复合集流体。例如，作为金属箔片，可以采用铜箔。复合集流体可包括高分子材料基层和形成于高分子材料基材至少一个表面上的金属层。复合集流体可通过将金属材料形成在高分子材料基材上而形成。其中，金属材料包括但不限于铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等，高分子材料基材包括但不限于聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等基材。
在一些实施方式中，负极活性材料还可包含本领域公知的用于电池的其他负极活性材料。作为示例，其他负极活性材料可包括以下材料中的至少一种：人造石墨、天然石墨、软炭、硬炭、硅基材料、锡基材料和钛酸锂等。所述硅基材料可选自单质硅、硅氧化合物、硅碳复合物、硅氮复合物以及硅合金中的至少一种。所述锡基材料可选自单质锡、锡氧化合物以及锡合金中的至少一种。但本申请并不限定于这些其他材料，还可以使用其他可被用作电池负极活性材料的传统材料。这些其他负极活性材料可以 仅单独使用一种，也可以将两种以上组合使用。
所述负极活性材料在负极膜层中的重量比为70-100重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括粘结剂。所述粘结剂可选自丁苯橡胶(SBR)、聚丙烯酸(PAA)、聚丙烯酸钠(PAAS)、聚丙烯酰胺(PAM)、聚乙烯醇(PVA)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的至少一种。所述粘结剂在负极膜层中的重量比为0-30重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括导电剂。导电剂可选自超导碳、炭黑(例如乙炔黑、科琴黑)、碳点、碳纳米管、石墨烯及碳纳米纤维中的至少一种。所述导电剂在负极膜层中的重量比为0-20重量％，基于负极膜层的总重量计。
在一些实施方式中，负极膜层还可选地包括其他助剂，例如增稠剂(如羧甲基纤维素钠(CMC-Na))等。所述其他助剂在负极膜层中的重量比为0-15重量％，基于负极膜层的总重量计。
在一些实施方式中，可以通过以下方式制备负极极片：将上述用于制备负极极片的组分，例如负极活性材料、导电剂、粘结剂和任意其他组分分散于溶剂(例如去离子水)中，形成负极浆料，其中所述负极浆料固含量为30-70wt％，室温下的粘度调整到2000-10000mPa·s；将所得到的负极浆料涂覆在负极集流体上，经过干燥工序，冷压例如对辊，得到负极极片。负极粉末涂布单位面密度为75-220g/m 2，负极极片压实密度1.2-2.0g/m 3。
电解质
电解质在正极极片和负极极片之间起到传导离子的作用。本申请对电解质的种类没有具体的限制，可根据需求进行选择。例如，电解质可以是液态的、凝胶态的或全固态的。
在一些实施方式中，所述电解质采用电解液。所述电解液包括电解质盐和溶剂。
在一些实施方式中，电解质盐可选自六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、高氯酸锂(LiClO 4)、六氟砷酸锂(LiAsF 6)、双氟磺酰亚胺锂(LiFSI)、双三氟甲磺酰亚胺锂(LiTFSI)、三氟甲磺酸锂(LiTFS)、二氟草酸硼酸锂(LiDFOB)、二草酸硼酸锂(LiBOB)、二氟磷酸锂(LiPO 2F 2)、二氟二草酸磷酸锂(LiDFOP)及四氟草酸磷酸 锂(LiTFOP)中的一种或几种。所述电解质盐的浓度通常为0.5-5mol/L。
在一些实施方式中，溶剂可选自氟代碳酸乙烯酯(FEC)、碳酸亚乙酯(EC)、碳酸亚丙基酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
在一些实施方式中，所述电解液还可选地包括添加剂。例如添加剂可以包括负极成膜添加剂、正极成膜添加剂，还可以包括能够改善电池某些性能的添加剂，例如改善电池过充性能的添加剂、改善电池高温或低温性能的添加剂等。
隔离膜
在一些实施方式中，二次电池中还包括隔离膜。本申请对隔离膜的种类没有特别的限制，可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构隔离膜。
在一些实施方式中，隔离膜的材质可选自玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏二氟乙烯中的至少一种。隔离膜可以是单层薄膜，也可以是多层复合薄膜，没有特别限制。在隔离膜为多层复合薄膜时，各层的材料可以相同或不同，没有特别限制。
在一些实施方式中，所述隔离膜的厚度为6-40μm，可选为12-20μm。
在一些实施方式中，正极极片、负极极片和隔离膜可通过卷绕工艺或叠片工艺制成电极组件。
在一些实施方式中，二次电池可包括外包装。该外包装可用于封装上述电极组件及电解质。
在一些实施方式中，二次电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。二次电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对二次电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池5。
在一些实施方式中，参照图2，外包装可包括壳体51和盖板53。其中，壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔 连通的开口，盖板53能够盖设于所述开口，以封闭所述容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件52。电极组件52封装于所述容纳腔内。电解液浸润于电极组件52中。二次电池5所含电极组件52的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
在一些实施方式中，二次电池可以组装成电池模块，电池模块所含二次电池的数量可以为一个或多个，具体数量本领域技术人员可根据电池模块的应用和容量进行选择。
在电池模块中，多个二次电池5可以是沿电池模块的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可以通过紧固件将该多个二次电池5进行固定。
可选地，电池模块还可以包括具有容纳空间的外壳，多个二次电池5容纳于该容纳空间。
在一些实施方式中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以为一个或多个，具体数量本领域技术人员可根据电池包的应用和容量进行选择。
在电池包中可以包括电池箱和设置于电池箱中的多个电池模块。电池箱包括上箱体和下箱体，上箱体能够盖设于下箱体，并形成用于容纳电池模块的封闭空间。多个电池模块4可以按照任意的方式排布于电池箱中。
另外，本申请还提供一种用电装置，所述用电装置包括本申请提供的二次电池、电池模块、或电池包中的至少一种。所述二次电池、电池模块、或电池包可以用作所述用电装置的电源，也可以用作所述用电装置的能量存储单元。所述用电装置可以包括移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于此。
作为所述用电装置，可以根据其使用需求来选择二次电池、电池模块或电池包。
图3是作为一个示例的用电装置。该用电装置为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该用电装置对二次电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
作为另一个示例的装置可以是手机、平板电脑、笔记本电脑等。该装置通常要求 轻薄化，可以采用二次电池作为电源。
实施例
为了使本申请所解决的技术问题、技术方案及有益效果更加清楚，以下将结合实施例和附图对本申请进行进一步详细说明。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。以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本申请及其应用的任何限制。基于本申请中的实施例，本领域普通技术人员在没有付出创造性劳动前提下所获得的所有其他实施例都属于本申请保护的范围。
实施例中未注明具体技术或条件的，按照本领域内的文献所描述的技术或条件或者按照产品说明书进行。所用试剂或仪器未注明生产厂商者，均为可以通过市购获得的常规产品。
一、制备实施例
负极活性材料的制备
制备实施例1
(1)将10g石墨粉末放入250mL烧杯中，加入1g NaNO3、40mL浓H2SO4、6gKMnO4，后在冰水浴中充分搅拌10min，然后置于热水浴中加热至35℃继续搅拌30min；然后加入100mL去离子水，温度加热至100℃继续搅拌30min，最后加入30mL H2O2；将上述混合液静置，吸液管移走上层液体后，加入100mL去离子水搅拌均匀，加热至100℃搅拌30min，得到氧化石墨烯溶液；
(2)向所述氧化石墨烯溶液中加入1g Si粉，在100℃温度下用烧杯搅拌均匀30min，得到混合溶液；
(3)将上述混合溶液用布氏漏斗过滤，并用去离子水洗涤至中性，将滤饼放入真空干燥箱在-0.1MPa下干燥6h，得到固体；
(4)将上述固体移至管式炉内在氮气保护下加热至500℃，保持12h，然后自然冷却至室温；取出煅烧后的材料，在研钵中研磨30min后，即制得所述负极活性材料。所述负极活性材料的产品参数汇总于表1中。
制备实施例2：改变加入硅原料的温度
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中将温度设为70℃。
制备实施例3：改变加入硅原料的温度
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中将温度设为80℃。
制备实施例4：改变加入硅原料的温度
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中将温度设为90℃。
制备实施例5：制备不同硅含量的负极活性材料
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中硅粉用量为0.5g。
制备实施例6：制备不同硅含量的负极活性材料
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中硅粉用量为0.75g。
制备实施例7：制备不同硅含量的负极活性材料
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中硅粉用量为1.25g。
制备实施例8：改变含硅材料的种类
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中用氧化亚硅SiO替换硅粉。
制备实施例9：改变含硅材料的种类
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中用SiO 2物质替换硅粉。
制备实施例10：改变煅烧温度
重复制备实施例1的步骤，其不同之处在于，在步骤(4)中加热至300℃。
制备实施例11：改变煅烧温度
重复制备实施例1的步骤，其不同之处在于，在步骤(4)中加热至400℃。
制备实施例12：改变煅烧温度
重复制备实施例1的步骤，其不同之处在于，在步骤(4)中加热至600℃。
制备对比例1：硅粉加入过多
重复制备实施例1的步骤，其不同之处在于，在步骤(2)中加入硅粉2.0g。
制备对比例2：管式炉加热温度低于300℃
重复制备实施例1的步骤，其不同之处在于，在步骤(4)中加热至250℃。
制备对比例3：
(1)将10g石墨粉末放入250mL烧杯中，加入1g NaNO3、40mL浓H2SO4、6gKMnO4，后在冰水浴中充分搅拌10min，然后置于热水浴中加热至35℃继续搅拌30min；然后加入100mL去离子水，温度加热至100℃继续搅拌30min，最后加入30mL H2O2；将上述混合液静置，吸液管移走上层液体后，加入100mL去离子水搅拌均匀， 加热至100℃搅拌30min，得到氧化石墨烯溶液；
(2)将上述溶液过滤，并用去离子水洗涤至中性，将滤饼放入真空干燥箱在-0.1MPa下干燥6h，得到固体；
(3)将上述固体移至管式炉内在氮气保护下加热至500℃，保持12h，然后自然冷却至室温，得到煅烧后的材料；
(4)将上述煅烧后的材料分散于去离子水中，然后加入1g Si粉在100℃温度下搅拌30min，得到混合溶液；然后利用真空抽滤机过滤并用真空干燥机干燥，制得所述负极活性材料。
制备实施例2-12的负极活性材料和制备对比例1-3的负极活性材料的产品参数详见表1。
表1各制备实施例和制备对比例的产品参数
Figure PCTCN2022126798-appb-000001
二、应用实施例
实施例1
1)正极极片的制备
将正极活性材料镍钴锰酸锂、导电炭黑SP及粘结剂PVDF按照重量比98:1:1分散至溶剂NMP中进行混合均匀，得到正极浆料；将正极浆料均匀涂布于正极集流体铝箔上，经烘干、冷压后，得到正极极片，其单位面积的涂覆量为0.27g/1540.25mm 2。
2)负极极片的制备
将制备实施例1的负极活性材料、增稠剂羧甲基纤维素钠、粘接剂丁苯橡胶、导电剂乙炔黑，按照质量比97:1:1:1进行混合，加入去离子水，在真空搅拌机作用下获得负极浆料；将负极浆料均匀涂覆在铜箔上；将铜箔在室温晾干后转移至120℃烘箱干燥1h，然后过冷压、分切得到负极片，其单位面积的涂覆量为0.17g/1540.25mm 2。
3)隔离膜
选用12μm厚的聚丙烯隔离膜。
4)电解液的制备
有机溶剂为含有碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)和碳酸二乙酯(DEC)的混液，其中，EC、EMC和DEC的体积比为20:20:60。在含水量<10ppm的氩气气氛手套箱中，将充分干燥的锂盐LiPF6溶解于有机溶剂中，混合均匀，获得电解液。其中，锂盐的浓度为1mol/L。
5)电池的制备
将正极片、隔离膜、负极片按顺序叠好，使隔离膜处于正、负极片之间起到隔离的作用，再卷绕成方形的裸电芯后，装入铝塑膜，然后在80℃下烘烤除水后，注入10g相应的非水电解液、封口，经静置、热冷压、化成、夹具、分容等工序后，得到容量为4000mAh的成品电池。
实施例2-12的二次电池和对比例1-3的二次电池与实施例1的二次电池制备方法相似，但是使用对应的制备实施例的负极活性材料。
三、电池性能测试
1.循环性能测试
将电池1C电流恒流充电到4.35V，继续恒压充电，直至充电电流小于0.05C后截 止；暂停5min；1C电流恒流放电到2.5V；暂停5min。以上为电池的一个充放电循环，不断重复，直至电池容量衰减到初始值的80％，记录循环圈数。
2.电池的克容量测试
电池的容量测试将锂离子电池在25℃的恒温环境下静置2h，然后在2.5V～4.35V下，按照1/3C充电至4.35V，然后在4.35V下恒压充电至电流≤0.05mA，静置5min，然后按照1C放电至2.5V，记录该电池的容量C 放。
所述克容量＝所述电池的容量C 放(mAh)/正极活性材料的质量(g)。
3.充电倍率测试
在25℃下，充电倍率分别为1C、2C、3C，从0％SOC充到100％SOC，然后均以0.33C放电至0％SOC，对比不同充电倍率下的放电容量。
4.10-90％SOC的最大的电流倍率
利用三电极叠片电芯，在室温下从10％SOC充电至90％SOC，同时在该SOC范围内进行试电流测试，测试阳极到达0电位时最大的电流倍率。
四、各实施例、对比例测试结果
按照上述方法分别制备各实施例和对比例的电池，并测量各项性能参数，结果见下表2。
表2各实施例和对比例的性能测试
Figure PCTCN2022126798-appb-000002
通过上述实施例和对比例可得知，本申请的负极活性材料中微孔和介孔的体积增 大，改善了负极活性材料内部的嵌锂通道，从而增大了其克容量，使得相应的电池具有良好的快充能力和循环性能，例如，本申请的克容量均大于500mAh/g，10-90％SOC的最大电流倍率均大于4C。
需要说明的是，本申请不限定于上述实施方式。上述实施方式仅为示例，在本申请的技术方案范围内具有与技术思想实质相同的构成、发挥相同作用效果的实施方式均包含在本申请的技术范围内。此外，在不脱离本申请主旨的范围内，对实施方式施加本领域技术人员能够想到的各种变形、将实施方式中的一部分构成要素加以组合而构筑的其它方式也包含在本申请的范围内。

Claims (16)

  1. 一种硅掺杂石墨烯的负极活性材料，其包含石墨烯和设置在所述石墨烯内部的含硅材料，其中所述负极活性材料包含孔，其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g。
  2. 根据权利要求1所述的负极活性材料，其特征在于，所述微孔与介孔的体积的比值为0.3-4：1。
  3. 根据权利要求1或2所述的负极活性材料，其特征在于，孔径大于50nm的大孔的体积为0.005～0.20cm 3/g。
  4. 根据权利要求1-3中任一项所述的负极活性材料，其特征在于，所述微孔、介孔和大孔的体积比为(1-10)：(0.5-5)：1。
  5. 根据权利要求1-4中任一项所述的负极活性材料，其特征在于，所述负极活性材料的比表面积为10-50m 2/g。
  6. 根据权利要求1-5中任一项所述的负极活性材料，其特征在于，所述含硅材料为平均体积粒径D v50为100～300nm的无机颗粒。
  7. 根据权利要求1-6中任一项所述的负极活性材料，其特征在于，所述含硅材料选自单质硅、硅的氧化物、硅酸盐、硅碳材料和其组合。
  8. 根据权利要求1-7中任一项所述的负极活性材料，其特征在于，所述含硅材料的含量为0.3％-5％，基于所述负极活性材料的总重量计。
  9. 根据权利要求1-8中任一项所述的负极活性材料，其特征在于，所述石墨烯的石墨化程度为90％-98％。
  10. 一种制备负极活性材料的方法，其包括
    (1)提供氧化石墨烯溶液；
    (2)在比氧化石墨烯溶液中使用的溶剂的沸点低30℃的温度至氧化石墨烯溶液中使用的溶剂的沸点的温度下，将含硅原料加入所述氧化石墨烯溶液中混合；
    (3)将步骤(2)的产物干燥，得到固体；
    (4)将步骤(3)的固体还原，制得所述负极活性材料；
    其中所述负极活性材料包含石墨烯和掺杂在所述石墨烯内部的硅，其中所述负极活性材料包含孔，其中，孔径＜2nm的微孔的体积为0.1-0.80cm 3/g，孔径在2～50nm范围内的介孔的体积为0.12-0.45cm 3/g。
  11. 根据权利要求7所述的方法，其特征在于，在步骤(1)中，所述氧化石墨烯溶液中使用的溶剂为水。
  12. 根据权利要求7或8所述的方法，其特征在于，在步骤(2)中混合时间为30-60min。
  13. 根据权利要求7-9中任一项所述的方法，其特征在于，在步骤(4)中所述还原在300-600℃的温度下进行。
  14. 根据权利要求7-10中任一项所述的方法，其特征在于，在步骤(4)中所述还原在惰性气氛中进行8小时-20小时。
  15. 一种二次电池，其特征在于，
    包括权利要求1-9中任一项所述的负极活性材料或根据权利要求10-14中任一项所述的方法制备的负极活性材料。
  16. 一种用电装置，其特征在于，包括选自权利要求15所述的二次电池。
PCT/CN2022/126798 2022-10-21 2022-10-21 硅掺杂石墨烯的负极活性材料、制备方法、二次电池和用电装置 WO2024082292A1 (zh)

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KR20130015719A (ko) * 2011-08-04 2013-02-14 연세대학교 산학협력단 메조동공구조 실리콘 산화물/그래핀 복합체 및 그 제조 방법
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