WO2023029889A1 - 负极材料及其制备方法、锂离子电池 - Google Patents

负极材料及其制备方法、锂离子电池 Download PDF

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WO2023029889A1
WO2023029889A1 PCT/CN2022/110770 CN2022110770W WO2023029889A1 WO 2023029889 A1 WO2023029889 A1 WO 2023029889A1 CN 2022110770 W CN2022110770 W CN 2022110770W WO 2023029889 A1 WO2023029889 A1 WO 2023029889A1
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negative electrode
electrode material
carbon
active material
mixing
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PCT/CN2022/110770
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English (en)
French (fr)
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何鹏
肖称茂
任建国
贺雪琴
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贝特瑞新材料集团股份有限公司
惠州市鼎元新能源科技有限公司
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Application filed by 贝特瑞新材料集团股份有限公司, 惠州市鼎元新能源科技有限公司 filed Critical 贝特瑞新材料集团股份有限公司
Priority to JP2023516622A priority Critical patent/JP2023542868A/ja
Priority to EP22863030.7A priority patent/EP4207375A1/en
Priority to US18/247,937 priority patent/US20240021833A1/en
Priority to KR1020237008557A priority patent/KR20230051682A/ko
Publication of WO2023029889A1 publication Critical patent/WO2023029889A1/zh

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    • 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
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Definitions

  • the present application relates to the technical field of negative electrode materials, in particular, to negative electrode materials, preparation methods thereof, and lithium ion batteries.
  • the present application provides a negative electrode material, a preparation method thereof, and a lithium ion battery, which can effectively suppress the volume expansion of the negative electrode material and improve battery cycle performance, and the preparation method can reduce the preparation cost.
  • a negative electrode material the negative electrode material includes aggregates, the aggregates include active materials and carbon materials, wherein the porosity of the negative electrode material is ⁇ 10%, and the target area in the negative electrode material Proportion C ⁇ 15%,
  • the target area ratio C is obtained by the following test method:
  • the negative electrode material of this embodiment includes an aggregate, and the aggregate includes an active material, a carbon material, and a conductivity enhancer.
  • the target area ratio C of the negative electrode material is ⁇ 15%. If the target area ratio C is controlled within this range, the active material maintains an appropriate spacing, which effectively avoids the self-agglomeration of the active material, and can avoid the loss of electrical contact during the lithium-deintercalation process. It is also conducive to the penetration of subsequent carbon materials, enhancing the combination of active materials and carbon materials, thereby improving the electrochemical performance of the material; the aggregate has a small porosity, and the electrolyte is not easy to penetrate into the inside of the aggregate. It is beneficial to protect the active material particles inside, can effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, SiO x (0 ⁇ x ⁇ 2), Fe, Mg, Ti, Zn, Al, P and Cu .
  • the median diameter of the active material is 1 nm to 500 nm.
  • the carbon material includes at least one of amorphous carbon, crystalline carbon and mesocarbon microspheres.
  • the mass ratio of the active material to the carbon material is (20-70):(10-80).
  • the aggregates further include metal oxides.
  • the metal oxide is distributed between the active material, and the carbon material is filled between the active material and the metal oxide.
  • pores there are pores between the active material and the metal oxide, and the carbon material is filled in the pores.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, Mg, Al, At least one of Ca and Zn.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2.
  • the mass ratio of the metal oxide to the active material is (1-20):100.
  • the aggregate further includes a conductivity enhancer.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • the conductive carbon includes at least one of carbon nanotubes, carbon fibers, and graphite fibers.
  • the conductivity of the conductivity enhancer is >10 2 S/m.
  • the conductivity enhancer is in the form of flakes and/or strips, and the aspect ratio of the conductivity enhancer is 2-3000.
  • the mass ratio of the conductivity enhancer to the active material is (0.1 ⁇ 10):100.
  • the tensile strength of the conductivity enhancer is ⁇ 500 MPa.
  • the negative electrode material further includes a carbon layer covering at least part of the surface of the aggregate.
  • the material of the carbon layer includes amorphous carbon.
  • the carbon layer has a thickness of 10 nm to 1500 nm.
  • the median particle size of the negative electrode material is 0.5 ⁇ m to 30 ⁇ m.
  • the specific surface area of the negative electrode material is ⁇ 10m 2 /g.
  • the compressive hardness of the negative electrode material is ⁇ 50 MPa.
  • the porosity of the negative electrode material is ⁇ 10%.
  • the aggregate density satisfies the following relationship: the difference between the test density of the aggregate and the average density of the aggregate is ⁇ 5%.
  • the present application provides a method for preparing an anode material, comprising the following steps:
  • the raw materials containing the active material, the first carbon source and the solvent are mixed and fully dispersed to increase the dispersion degree of the active material in the first precursor, and then the obtained first precursor is heated at 600 ° C to 1200 ° C °C for one heat treatment to obtain the second precursor, and then the second precursor is subjected to densification treatment.
  • the above-mentioned substances are agglomerated to form aggregates, which can increase the dispersion of active materials in the aggregates and reduce the density of the aggregates. Porosity, the whole preparation process is simple, and the prepared negative electrode material can effectively inhibit volume expansion, reduce expansion rate, and improve battery cycle performance.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, SiO x (0 ⁇ x ⁇ 2), Fe, Mg, Ti, Zn, Al, P and Cu .
  • the first carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, At least one of polyvinylidene fluoride, polyacrylonitrile, polyvinyl chloride, and asphalt.
  • the mass ratio of the first carbon source to the active material is (5-40):100;
  • the solvent includes an organic solvent.
  • the organic solvent includes at least one of methanol, ethanol, ethylene glycol, propanol, isopropanol, glycerol, n-butanol, isobutanol and pentanol.
  • additives are added in the step of mixing and fully dispersing the raw materials including the active material, the first carbon source and the solvent.
  • the additive includes at least one of a surfactant and a coupling agent.
  • the surfactant includes n-octadecanoic acid, lauric acid, polyacrylic acid, sodium dodecylbenzenesulfonate, n-eicosic acid, palmitic acid, myristic acid, undecanoic acid, At least one of hexaalkyltrimethylammonium bromide and polyvinylpyrrolidone.
  • the coupling agent includes a silane coupling agent
  • the silane coupling agent includes ⁇ -aminopropyltriethoxysilane, ⁇ -glycidyl etheroxypropyltrimethoxysilane, ⁇ -methyl Acryloyloxypropyltrimethoxysilane.
  • the mass ratio of the active substance to the additive is (15-120):(1-10).
  • metal oxides are also added in the step of mixing and fully dispersing the raw materials including the active material, the first carbon source and the solvent.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, Mg, Al, At least one of Ca and Zn.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2.
  • the mass ratio of the metal oxide to the active material is (1-20):100.
  • a conductivity enhancer is also added in the step of mixing and fully dispersing the raw materials including the active material, the first carbon source and the solvent.
  • the mass ratio of the conductivity enhancer to the active material is (0.1-10):100.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • the conductive carbon includes at least one of carbon nanotubes, carbon fibers, and graphite fibers.
  • the conductivity of the conductivity enhancer is >10 2 S/m.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the aspect ratio of the conductivity enhancer is 2-3000.
  • the sufficient dispersion treatment method includes at least one of mechanical stirring, ultrasonic dispersion, and grinding dispersion.
  • the mixing of the raw materials comprising the active material, the first carbon source and the solvent adopts a staged mixing method.
  • the mixing of the raw materials comprising the active material, the first carbon source and the solvent specifically includes: mixing the active material with the solvent to form a first premix, and mixing the first carbon source with the The solvents are mixed to form a second premix, and the first premix is mixed with the second premix.
  • the step of preparing the first precursor includes mixing and fully dispersing the active material, the first carbon source and the solvent, and then performing drying treatment to obtain the first precursor.
  • the temperature of the drying treatment is 40° C. to 600° C. and the time is 1 h to 15 h.
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment, and dipping treatment.
  • the fusion treatment is mechanical fusion.
  • the rotation speed of the fusion machine used for the mechanical fusion is 300r/min-3000r/min.
  • the fusion machine used for the mechanical fusion has a gap width of 0.01 cm to 0.9 cm.
  • the mechanofusion time is at least 0.5 h.
  • the time for the primary heat treatment is 1 h to 10 h.
  • a protective gas is passed through the primary heat treatment process.
  • the protective gas includes at least one of nitrogen, helium, neon, argon and krypton.
  • the method further includes carbon-coating the aggregate.
  • the step of carbon coating treatment includes: mixing the second precursor and the second carbon source, and performing secondary heat treatment.
  • the mass ratio of the second precursor to the second carbon source is (30-100):(10-70).
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source, and secondary heat treatment.
  • the second carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, At least one of polyvinylidene fluoride, polyacrylonitrile, polyvinyl chloride and asphalt.
  • the mass ratio of the aggregates to the second carbon source is (15-100):(10-70).
  • the temperature of the secondary heat treatment is 600° C. to 1200° C.
  • the time of the secondary heat treatment is 1 h to 10 h.
  • a protective gas is passed through the secondary heat treatment process.
  • the protective gas includes at least one of nitrogen, helium, neon, argon and krypton.
  • the present application provides a lithium ion battery, which includes the negative electrode material described in the first aspect or the negative electrode material prepared according to the preparation method described in the second aspect.
  • the negative electrode material of this embodiment includes an aggregate, and the aggregate includes an active material, a carbon material, and a conductivity enhancer.
  • the proportion of the target area of the negative electrode material is C ⁇ 15%.
  • the active material maintains an appropriate spacing, effectively avoiding the self-agglomeration of the active material, and avoiding the loss of electrical contact during the lithium-deintercalation process. It is also beneficial to the subsequent carbon materials. penetration, enhance the combination of active material and carbon material, and then improve the electrochemical performance of the material; the aggregate has a small porosity, and the electrolyte is not easy to penetrate into the aggregate, and the aggregate structure is conducive to protecting the internal activity. Material particles can effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • the raw materials containing the active material, the first carbon source and the solvent are mixed and fully dispersed, which can improve the dispersion degree of the active material in the first precursor, and then the obtained first
  • the precursor is subjected to a heat treatment to obtain the second precursor, and then the second precursor is subjected to densification treatment.
  • the above substances are agglomerated to form aggregates, which can increase the dispersion of active substances in the aggregates and reduce the concentration of aggregates.
  • the porosity is high, the whole preparation process is simple, and the prepared negative electrode material can effectively inhibit the volume expansion, reduce the expansion rate, and improve the battery cycle performance.
  • the preparation method provided in the present application can be applied to scale-up production, and the prepared negative electrode material can effectively improve the stability of lithium battery charging and discharging cycles and effectively reduce the expansion rate of the negative electrode material.
  • Fig. 1 is the schematic flow chart of the preparation method of the negative electrode material that the embodiment of the present application provides;
  • Fig. 2 is the scanning electron microscope (SEM) picture of the negative electrode material that the application embodiment 1 prepares;
  • Fig. 3 is the XRD pattern of the negative electrode material prepared in Example 1 of the present application.
  • Fig. 4 is the first charge-discharge curve of the negative electrode material prepared in Example 1 of the present application.
  • FIG. 5 is a cycle performance curve of the negative electrode material prepared in Example 1 of the present application.
  • the negative electrode material includes aggregates, and the aggregates include active materials and carbon materials, wherein the porosity of the negative electrode material is ⁇ 10%, and the target area ratio C in the negative electrode material is ⁇ 15%,
  • the target area ratio C is obtained by the following test method:
  • the negative electrode material of this embodiment includes an aggregate, and the aggregate includes an active material and a carbon material.
  • the proportion of the target area of the negative electrode material is C ⁇ 15%.
  • the active material maintains an appropriate spacing, effectively avoiding the self-agglomeration of the active material, and avoiding the loss of electrical contact during the lithium-deintercalation process. It is also beneficial to the subsequent carbon materials. penetration, enhance the combination of active material and carbon material, and then improve the electrochemical performance of the material; the aggregate has a small porosity, and the electrolyte is not easy to penetrate into the aggregate, and the aggregate structure is conducive to protecting the internal activity. Material particles can effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • the porosity of the negative electrode material is less than or equal to 10%. At this time, the porosity of the negative electrode material is low, that is, its density is very high. On the one hand, it helps to improve the energy density of the composite material. damage, the electrolyte is not easy to penetrate into the inside of the aggregate, which is conducive to protecting the active material particles inside, reducing the contact probability between the electrolyte and the active material, and thus conducive to the formation of a stable solid electrolyte film; and the highly dense aggregate has High compressive hardness can offset the stress effect caused by expansion, improve the structural stability of the negative electrode material, effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • the porosity of the negative electrode material can be 10%, 9%, 9.5%, 8%, 8.5%, 7.5%, 7%, 6.5%, 6% or 5%, etc., of course, it can also be Other values within the above range are not limited here. It can be understood that the negative electrode material has a low porosity, that is, its density is high, which is conducive to the formation of a stable solid electrolyte film and reduces the contact between the electrolyte and the active material. Preferably, the porosity of the negative electrode material is ⁇ 3%.
  • the compressive hardness of the negative electrode material is greater than or equal to 50 MPa.
  • the compressive hardness of the negative electrode material can be 50MPa, 250MPa, 300MPa, 450MPa, 500MPa, 750MPa, 900MPa, 1150MPa, 1200MPa or 1250MPa, etc., of course, it can also be other values within the above range, which is not limited here .
  • the compressive hardness of the negative electrode material is ⁇ 100 MPa, more preferably, the compressive hardness of the negative electrode material is ⁇ 200 MPa.
  • the aggregate density satisfies the following relationship: the difference between the tested density of aggregates and the average density of aggregates is ⁇ 5%. The closer the density of the aggregate particles is to the average density, the smaller the difference, indicating that the pores inside the particles are less and denser, which is conducive to the formation of a stable solid electrolyte film and reduces the contact between the electrolyte and the active material.
  • the aggregate density is calculated as follows: ( ⁇ 1 ⁇ 2)/ ⁇ 2 ⁇ 5%, where ⁇ 1 is the test density of the aggregate, and ⁇ 2 is the average density of the aggregate.
  • ⁇ 2 is the sum of the value of the mass percentage content of each component in the aggregate * the theoretical density of each component in the aggregate.
  • ⁇ 2 mass percentage of the active material in the aggregate*theoretical density of the active material+mass percentage of the conductive enhancer in the aggregate Content*theoretical density of conductive enhancer+mass percentage content of carbon material in the aggregate*theoretical density of carbon material.
  • ⁇ 2 mass percentage of active materials in aggregates*theoretical density of active materials+mass percentage of metal oxides in aggregates * Theoretical density of metal oxide + mass percentage of conductive enhancer in aggregate * theoretical density of conductive enhancer + mass percentage of carbon material in aggregate * theoretical density of carbon material.
  • the active material refers to a material that can react with lithium to perform lithium intercalation and deintercalation.
  • the active material includes at least one of metal element, metal oxide and metal alloy.
  • the metal includes at least one of Li, Na, K, Sn, Ge, Si, Fe, Mg, Ti, Zn, Al, P and Cu.
  • Elemental metal refers to the above-mentioned elemental metal
  • metal oxide refers to the oxide of the above-mentioned metal
  • metal alloy refers to an alloy containing at least one of the above-mentioned metals, such as silicon-lithium alloy, silicon-magnesium alloy, and the like.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, SiO x (0 ⁇ x ⁇ 2), Fe, Mg, Ti, Zn, Al, P, and Cu.
  • the active material is a particle, and the median diameter of the active material is 1 nm to 500 nm. Specifically, it can be 1nm, 5nm, 10nm, 15nm, 20nm, 30nm, 40nm, 50nm, 100nm, 200nm, 300nm, 400nm or 500nm, etc. Of course, it can also be other values within the above range, which is not limited here.
  • the nanoscale active material has high surface energy and is prone to agglomeration during the charge and discharge process.
  • the particles have a strong structure and can inhibit the volume expansion of silicon.
  • the median diameter of the active material is 1 nm to 200 nm, more preferably 1 nm to 100 nm.
  • the carbon material includes at least one of amorphous carbon, crystalline carbon, and mesocarbon microspheres.
  • the mass ratio of the active material to the carbon material is (20-70):(10-80). Specifically, it can be 20:10, 20:20, 20:30, 20:50, 20:60, 20:80, 40:10, 40:50, 40:80, 50:70, 50:80 and so on. Of course, other values within the above range may also be used, which are not limited here.
  • the aggregates also include metal oxides. Combining the metal oxides with the active material can reduce the expansion of the active material, improve long-term cycle performance, and the aggregate has higher compressive hardness.
  • the metal oxide is distributed among the active materials, and the carbon material is filled between the active material and the metal oxide.
  • pores between the active material and the metal oxide there are pores between the active material and the metal oxide, and the pores are filled with carbon materials. It can be understood that through the pore structure formed by the stacking and aggregation of active materials and metal oxides, the carbon material fills the pores, which can improve the structural stability of the aggregate, resist certain volume expansion stress, and reduce expansion.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, Mg, Al, Ca or at least one of Zn; specifically, the metal oxide may be SiO, GeO 2 , SnO 2 , ZnO, TiO 2 , Fe 3 O 4 , MgO, SiO 2 , CuO, and the like.
  • the volume expansion change rate of the selected metal oxide during the lithium intercalation process is lower than that of the active material. Therefore, compounding the metal oxide with the active material can reduce the expansion of the active material and improve the long-cycle performance.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2. It should be noted that, when the metal oxide is elongated, the aspect ratio specifically refers to the ratio of the length of the particle to the particle diameter of the particle; when the metal oxide is flaky, the aspect ratio specifically refers to the The ratio of the length to width of an oxide. Specifically, the aspect ratio of the metal oxide can be 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 12, 15, 17, 18, 22, etc. Of course, it can also be Other values within the above range are not limited here. According to many experiments, it has been found that when the aspect ratio of the metal oxide is greater than 2, the physical binding force between the metal oxide and the active material can be improved, thereby better buffering the volume expansion change of the active material and improving cycle performance.
  • the mass ratio of the metal oxide to the active material is (1-20):100.
  • the mass ratio of the metal oxide to the active material can be 1:100, 1.5:100, 2:100, 3:100, 4.5:100, 5:100, 6:100, 7:100, 8:100, 9:100 and so on.
  • other values within the above range may also be used, which are not limited here. Too high a metal oxide content will lead to a decrease in the first efficiency of the material, and too low a metal oxide content will lead to a decrease in the rigidity of the aggregate structure and a decrease in particle cycle stability.
  • the aggregate also includes a conductivity enhancer.
  • the tensile strength of the conductivity enhancer is ⁇ 500 MPa
  • the dispersion degree N of the conductivity enhancer in the negative electrode material is greater than or equal to 1; wherein, the dispersion degree N is obtained by the following test method: the SEM section of the negative electrode material particle is divided into A region with an area of A ⁇ B, wherein A and B are both ⁇ 1 micron, counting the distribution of the conductivity enhancer in all regions of a single negative electrode material particle, there will be the number of regions with a distance between the conductivity enhancers ⁇ 10nm
  • the statistics are Na, and the number of areas where the spacing between the conductive enhancers is ⁇ 10nm is counted as Nb.
  • the uniform dispersion of the conductivity enhancer can effectively improve the transport of carriers inside the aggregate, enhance the conductivity of the aggregate, and the conductivity enhancer can effectively improve the structural stability of the aggregate, strengthen the structural strength of the aggregate, and avoid The stress change caused by the expansion effect of the active material maintains the structural stability of the aggregate, thereby improving the cycle stability of the material and reducing the expansion rate. Control the tensile strength of the conductivity enhancer within the range of ⁇ 500MPa.
  • the conductivity enhancer has excellent mechanical properties and can be used as a support for the structure to enhance the stability of the material. By controlling the minimum distance between the conductivity enhancers, it can make
  • the conductive enhancer can be filled with active materials, and the conductive enhancer can be used as a structural support to enhance the stability of the material, thereby buffering the volume expansion change of the active material and improving cycle performance.
  • the tensile strength of the conductivity enhancer can be 500MPa, 800MPa, 1Gpa, 5Gpa, 10Gpa, 25Gpa, 30Gpa, 45Gpa or 50Gpa, etc., of course, it can also be other values within the above range, which is not limited here.
  • the conductivity enhancer is distributed inside and/or on the surface of the aggregate.
  • the conduction enhancer is distributed among the active materials, and carbon material is filled between the active material and the conduction enhancer. It can be understood that by distributing the conductivity enhancer in the active material, the conductivity of the active material can be improved, and the transport of carriers in the active material can be improved.
  • pores are formed between the carbon material and the conductivity enhancer due to stacking and aggregation, and the pores are filled with active materials. It can be understood that the carbon material and the conductivity enhancer form a pore structure, so that the structural strength of the aggregate can be improved in the pores of the active material, and the stress change caused by the expansion of the active material can be resisted through the pore structure to maintain the stability of the aggregate structure.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • alloy material and conductive carbon.
  • any other conductive material with a tensile strength ⁇ 500 MPa can be used as a conductive enhancer.
  • the conductive carbon includes at least one of carbon nanotubes, carbon fibers, and graphite fibers.
  • the alloy material is an alloy with electrical conductivity > 10 2 S/m and tensile strength > 500 MPa.
  • the alloy material includes at least one of silicon alloy, aluminum alloy, copper alloy, aluminum alloy and lithium alloy.
  • the silicon alloy includes at least one of nickel-silicon alloy, iron-silicon alloy, copper-silicon alloy, silicon-manganese alloy and aluminum-silicon alloy.
  • the conductivity enhancer has a conductivity >10 2 S/m.
  • the conductivity of the conductivity enhancer may be 100 S/m, 10 3 S/m, 10 4 S/m, 10 5 S/m, 10 8 S/m, and the like.
  • the conductivity enhancer within this range can effectively improve the transport of carriers inside the aggregate and enhance the conductivity of the aggregate.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the aspect ratio of the conductivity enhancer is 2-3000. It should be noted that when the conductivity enhancer is strip-shaped, the aspect ratio specifically refers to the ratio of the length of the particle to the particle diameter of the particle, where the particle diameter refers to the length perpendicular to the length direction of the strip-shaped conductivity enhancer. The maximum linear distance between two points on the periphery of the section; when the metal oxide is in the form of a sheet, the aspect ratio specifically refers to the ratio of the length to the width of the sheet-shaped conductivity enhancer.
  • the aspect ratio of the conductivity enhancer can be 2, 30, 46, 150, 360, 670, 800, 900, 1500, 2000, or 3000, etc., and of course it can also be other values within the above-mentioned range. Do limited. According to many tests, it has been found that the conductivity enhancer with the aspect ratio within this range has excellent mechanical properties, and can be used as a structural support to enhance the stability of the material, thereby buffering the volume expansion change of the active material and improving cycle performance.
  • the conductivity enhancer has a tensile strength > 500 MPa. It should be noted that when the tensile strength of the conductivity enhancer is too low, it is difficult for the conductivity enhancer to resist the stress change caused by the expansion of the active material, and it is difficult to maintain the stability of the aggregate structure, which is not conducive to improving the cycle performance of the material.
  • the tensile strength of the conductive enhancer can be 500Mpa, 520Mpa, 550Mpa, 580Mpa, 600Mpa, 650Mpa, 700Mpa, 750Mpa or 800Mpa, etc., of course, it can also be other values within the above range , is not limited here.
  • the conductivity enhancer has excellent mechanical properties and can be used as a structural support to enhance the stability of the material, thereby buffering the volume expansion change of the active material , improve cycle performance.
  • the mass ratio of the conductivity enhancer to the active material is (0.1-10):100. Specifically, it can be 0.1:100, 0.5:100, 0.8:100, 1:100, 2:100, 3:100, 5:100, 6:100, 7:100, 8:100, 10:100 and so on. Of course, other values within the above range may also be used, which are not limited here.
  • the negative electrode material also includes a carbon layer covering at least part of the surface of the aggregate.
  • the carbon layer is distributed over the surface of the aggregate.
  • the carbon layer includes amorphous carbon.
  • the carbon layer has a thickness of 10 nm to 1500 nm. It can be understood that the carbon layer covering the surface of the aggregate can reduce the contact between the active material and the electrolyte, reduce the formation of passivation film, and improve the reversible capacity of the battery.
  • the thickness of the carbon layer can be 10nm, 50nm, 180nm, 200nm, 350nm, 400nm, 550nm, 700nm, 850nm, 900nm, 1050nm, 1200nm or 1500nm, etc., of course, it can also be other values within the above range, here No limit. If the carbon layer is too thick and the proportion of carbon is too high, it is not conducive to obtaining a composite material with high specific capacity; if the carbon layer is too thin, it is not conducive to increasing the conductivity of the negative electrode material and the volume expansion inhibition performance of the material is weak, resulting in a long-cycle performance price difference .
  • the thickness of the carbon layer is 50nm-800nm; more preferably, the thickness of the carbon layer is 100nm-500nm.
  • the porosity of the negative electrode material after the carbon layer is coated on the aggregate surface is ⁇ 10%, and the compressive hardness is ⁇ 50 MPa. Keeping the overall porosity and compressive hardness of the negative electrode material within this range can further improve the performance of the negative electrode material.
  • the median particle size of the negative electrode material is 0.5 ⁇ m ⁇ 30 ⁇ m. Specifically, it can be 0.5 ⁇ m, 1 ⁇ m, 5 ⁇ m, 8 ⁇ m, 10 ⁇ m, 13 ⁇ m, 15 ⁇ m, 18 ⁇ m, 20 ⁇ m, 25 ⁇ m or 30 ⁇ m, etc. Of course, it can also be other values within the above range, which is not limited here. It can be understood that controlling the median particle size of the negative electrode material within the above range is beneficial to the improvement of the cycle performance of the negative electrode material.
  • the specific surface area of the negative electrode material is ⁇ 10 m 2 /g. Specifically, it can be 10m 2 /g, 8m 2 /g, 7m 2 /g, 5m 2 /g, 3m 2 /g, 2m 2 /g, 1m 2 /g or 0.5m 2 /g, etc. Of course, it can also be Other values within the above range are not limited here. It can be understood that controlling the specific surface area of the negative electrode material within the above range is beneficial to suppress volume expansion and improve the cycle performance of the negative electrode material.
  • the negative electrode materials in the above embodiments can be combined arbitrarily if there is no conflict with each other, for example, the compressive hardness, porosity and density of the aggregates are limited in combination.
  • the present application provides a method for preparing a negative electrode material, as shown in Figure 1, the method includes the following steps:
  • Step S10 mixing and fully dispersing the raw materials including the active material, the first carbon source and the solvent, and then removing the solvent to obtain the first precursor;
  • Step S20 performing a heat treatment on the first precursor at 600° C. to 1200° C. to obtain a second precursor
  • Step S30 performing densification treatment on the second precursor to obtain aggregates.
  • the raw materials containing the active material, the first carbon source and the solvent are mixed and fully dispersed, which can increase the dispersion degree of the active material in the first precursor, and then the first precursor is heated at 600 ° C to 1200 ° C. °C for one heat treatment to obtain the second precursor, and then the second precursor is subjected to densification treatment.
  • the above-mentioned substances are agglomerated to form aggregates, which can increase the dispersion of active materials in the aggregates and reduce the density of the aggregates. Porosity, the whole preparation process is simple, and the prepared negative electrode material can effectively inhibit volume expansion, reduce expansion rate, and improve battery cycle performance.
  • Step S10 mixing and fully dispersing the raw materials including the active material, the first carbon source and the solvent, and then removing the solvent to obtain the first precursor.
  • the step of mixing the raw materials comprising the active material, the first carbon source and the solvent is performed in a staged mixing manner.
  • the active material can be mixed with a solvent to form a first premix
  • the first carbon source can be mixed with a solvent to form a second premix
  • the first premix can be mixed with the second premix to achieve classification mix.
  • an appropriate step-mixing operation is selected according to the step-wise mixing principle to fully disperse the active material, so as to achieve the target area ratio C ⁇ 15% in the final negative electrode material.
  • the treatment method for sufficient dispersion includes at least one of mechanical stirring, ultrasonic dispersion, and grinding dispersion.
  • sufficient dispersion is not limited to the above methods, and any method that can sufficiently disperse the active material to achieve the target area ratio C ⁇ 15% in the final negative electrode material is fine.
  • the active material refers to a material that can react with lithium to perform lithium intercalation and deintercalation.
  • the active material includes at least one of metal element, metal oxide and metal alloy. Further, the metal includes at least one of Li, Na, K, Sn, Ge, Si, Fe, Mg, Ti, Zn, Al, P and Cu.
  • the active material includes at least one of Li, Na, K, Sn, Ge, Si, SiO x (0 ⁇ x ⁇ 2), Fe, Mg, Ti, Zn, Al, P, and Cu.
  • the active material can be the above-mentioned simple metal, and the further active material can be specifically Si, Sn, Ge, Al.
  • the active material may also be an alloy formed of at least two of the above metals, such as a silicon-lithium alloy, a silicon-magnesium alloy, and the like.
  • the active material may also be oxides of the above metals, such as silicon oxide.
  • the active material includes at least two of metal element, metal alloy and metal oxide.
  • the active material is a particle, and the median diameter of the active material is 1 nm to 500 nm. Specifically, it can be 1nm, 5nm, 10nm, 15nm, 20nm, 30nm, 40nm, 50nm, 100nm, 200nm, 300nm, 400nm or 500nm, etc. Of course, it can also be other values within the above range, which is not limited here. Through many tests, it is found that the nano-scale active substance has a strong particle structure, which can inhibit the volume expansion of the active particle.
  • the median diameter of the active material is 1 nm to 200 nm, more preferably 1 nm to 100 nm.
  • the first carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, polyethylene At least one of vinylidene fluoride, polyacrylonitrile, polyvinyl chloride, and asphalt.
  • the solvent includes an organic solvent; the organic solvent includes at least one of methanol, ethanol, ethylene glycol, propanol, isopropanol, glycerol, n-butanol, isobutanol, and pentanol.
  • additives are also added in the step of mixing and fully dispersing the raw materials comprising the active material, the first carbon source and the solvent.
  • the additive can effectively enhance the stability of the connection between the active material and the first carbon source, thereby forming a firm system and reducing the expansion rate of the pole piece.
  • the mass ratio of the first carbon source to the active material is (5-40):100; specifically, it can be 5:100, 10:100, 15:100, 20:100, 25:100, 30: 100, 35:100, 38:100 or 40:100 etc.
  • the mass ratio of the first carbon source to the active material should not be too high, that is, the content of the first carbon source should not be too high, which is not conducive to the formation of a high-porosity precursor and affects subsequent processing.
  • the additive includes at least one of a surfactant and a coupling agent.
  • Surfactants include octadecanoic acid, lauric acid, polyacrylic acid, sodium dodecylbenzenesulfonate, n-eicosic acid, palmitic acid, myristic acid, undecanoic acid, cetyltrimethyl bromide At least one of chemical amines and polyvinylpyrrolidone.
  • Coupling agents include silane coupling agents, silane coupling agents include ⁇ -aminopropyltriethoxysilane, ⁇ -glycidyloxypropyltrimethoxysilane, ⁇ -methacryloxypropyltrimethoxysilane base silane.
  • a conductivity enhancer is also added in the step of mixing and fully dispersing the raw materials including the active material, the additive, the first carbon source and the solvent.
  • the conductivity enhancer includes at least one of alloy material and conductive carbon.
  • the conductive carbon includes at least one of carbon nanotubes, carbon fibers, and graphite fibers.
  • the conductivity of the conductivity enhancer is >10 2 S/m; specifically, the conductivity of the conductivity enhancer can be 100 S/m, 10 3 S/m, 10 4 S/m, 10 5 S/m m, 10 8 S/m, etc.
  • the conductivity enhancer is in the form of flakes and/or strips.
  • the aspect ratio of the conductivity enhancer is 2-3000. It should be noted that when the conductivity enhancer is strip-shaped, the aspect ratio specifically refers to the ratio of the length of the particle to the particle diameter of the particle, where the particle diameter refers to the length perpendicular to the length direction of the strip-shaped conductivity enhancer. The maximum linear distance between two points on the periphery of the section; when the conductivity enhancer is in the form of a sheet, the aspect ratio specifically refers to the ratio of the length to the width of the sheet-like conductivity enhancer.
  • the aspect ratio of the conductivity enhancer can be 2, 30, 46, 150, 360, 670, 800, 900, 1500, 2000, or 3000, etc., and of course it can also be other values within the above-mentioned range. Do limited. According to many tests, it has been found that the conductivity enhancer with the aspect ratio within this range has excellent mechanical properties, and can be used as a structural support to enhance the stability of the material, thereby buffering the volume expansion change of the active material and improving cycle performance.
  • the mass ratio of the conductivity enhancer to the active material is (0.1 ⁇ 10):100. Specifically, the mass ratio of the conductivity enhancer to the active material is 0.1:100, 0.5:100, 1:100, 2:100, 2.6:100, 3:100, 3.5:100, 4:100, 4.8:100, 6 :100, 7:100, 8.5:100 or 10:100 etc.
  • the mass ratio of the conductivity enhancer to the active material is 0.1:100, 0.5:100, 1:100, 2:100, 2.6:100, 3:100, 3.5:100, 4:100, 4.8:100, 6 :100, 7:100, 8.5:100 or 10:100 etc.
  • other values within the above range may also be used, which are not limited here.
  • metal oxides are also added in the step of mixing and fully dispersing the raw materials including the active material, the additive, the first carbon source and the solvent.
  • the general chemical formula of the metal oxide is M x O y , 0.2 ⁇ y/x ⁇ 3, wherein M includes Sn, Ge, Si, Fe, Cu, Ti, Na, Mg, Al, Ca and at least one of Zn.
  • the metal oxide is in the form of flakes and/or strips.
  • the aspect ratio of the metal oxide is greater than 2.
  • the mass ratio of the metal oxide to the active material is (1-20):100.
  • the mass ratio of the metal oxide to the active material can be 1:100, 1.5:100, 2:100, 3:100, 4.5:100, 5:100, 6:100, 7:100, 8:100, 10:100, 15:100, 20:100, etc.
  • other values within the above range may also be used, which are not limited here. If the content of metal oxide is too high, the initial efficiency of the material will decrease, and if the content of metal oxide is too low, the rigidity of the aggregate structure will decrease, and the cycle stability of the negative electrode material will decrease.
  • the sufficient dispersion treatment includes at least one of mechanical stirring, ultrasonic dispersion and grinding dispersion.
  • grinding and dispersing is used, so that the active substance can be dispersed, avoiding the agglomeration of the active substance, and the active substance can be dispersed into smaller nanoparticles.
  • the dispersion time of wet ball milling can be controlled within 0.5h-10h, and the components can be mixed more uniformly through sufficient grinding, so that the particle size of the active material particles can reach 1nm-500nm.
  • the raw materials including the active material, the first carbon source and the solvent are mixed and fully dispersed, and then the solvent is removed to obtain the first precursor.
  • the method of removing the solvent includes drying treatment.
  • the temperature of the drying treatment is 40°C to 600°C, specifically 40°C, 50°C, 80°C, 100°C, 120°C, 250°C, 380°C, 400°C, 500°C, 580°C or 600°C, etc.
  • the drying time is 1h to 15h, specifically 1h, 3h, 5h, 7h, 9h, 10h, 12h or 15h, etc.
  • the drying method can be furnace drying, freeze drying, stirring, etc. Evaporation to dryness, spray drying, etc., the drying treatment in this embodiment can remove the solvent in the precursor solution as much as possible.
  • the dried first precursor can also be dispersed.
  • the dispersion can be grinding and dispersing.
  • the dispersion time is 0.5h-9h, specifically 0.5h, 1.5h, 2.5h, 3.5h, 4.5h, 5.5h, 7.5h or 9h and so on, grinding and dispersing in this embodiment, control the particle size after dispersing.
  • a second carbon source may also be added during the process of dispersing the dried first precursor, and the mass ratio of the first precursor to the second carbon source is (10-80):10. Secondary drying was carried out after dispersion to obtain the carbon-coated first precursor.
  • Step S20 performing a heat treatment on the first precursor to obtain the second precursor.
  • the primary heat treatment may be, for example, vacuum sintering, hot pressing sintering or normal pressure sintering.
  • the temperature of the primary heat treatment ranges from 600°C to 1200°C, such as 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, etc.
  • the temperature of the primary heat treatment is 600°C-1000°C.
  • the time for one heat treatment is 1h to 10h, for example, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h or 10h.
  • the heating rate during heat treatment is 1°C/min to 30°C/min, specifically 1°C/min, 5°C/min, 10°C/min, 15°C/min, 20°C/min, 25°C/min or 30°C °C/min etc.
  • the heating rate during the heat treatment is 1° C./min to 15° C./min.
  • a protective gas is used in the heat treatment process, and the protective gas includes at least one of nitrogen, helium, neon, argon and krypton.
  • Step S30 performing densification treatment on the second precursor to obtain aggregates.
  • the porosity of the obtained aggregate is ⁇ 10%.
  • the densification treatment includes at least one of fusion treatment, kneading extrusion treatment, molding treatment, isostatic pressing treatment and impregnation treatment.
  • the fusion treatment is mechanical fusion.
  • the fusion treatment of the precursor is used to improve the compressive hardness of the negative electrode material, and then a heat treatment is performed to enhance the stability of the particle structure, and at the same time, it can enhance the connection stability between the active material and the first carbon source and reduce the porosity.
  • other methods can also be used for densification treatment, such as molding, isostatic pressing, impregnation and other processes, as long as the porosity of the aggregate is ⁇ 10%.
  • the compressive hardness of the aggregate is greater than or equal to 50MPa, and the compressive hardness of the aggregate can specifically be 50MPa, 250MPa, 300MPa, 450MPa, 500MPa, 750MPa, 900MPa, 1150MPa, 1200MPa or 1250MPa, etc. Of course, it can also be Other values within the above range are not limited here. Because of its strong rigidity and strong particle structure stability, it can resist a certain volume expansion stress, thereby reducing expansion and improving battery cycle stability.
  • the compressive hardness of the aggregate is ⁇ 100 MPa, more preferably, the compressive hardness of the aggregate is ⁇ 200 MPa.
  • the porosity of the final negative electrode material is ⁇ 10%
  • the compressive hardness of the negative electrode material is ⁇ 50MPa.
  • the porosity and compressive strength of the aggregate can be controlled according to the final carbon coating layer, so as to finally make the The porosity and compressive strength of the negative electrode material reached the target values.
  • the rotation speed of the fusion machine is 300r/min to 3000r/min, specifically 300r/min, 1000r/min, 1500r/min, 2000r/min, 2500r/min or 3000r/min, etc.
  • the fusion machine tool gap width is 0.01cm ⁇ 0.9cm, specifically 0.01cm, 0.05cm, 0.1cm, 0.15cm, 0.2cm, 0.25cm, 0.3cm, 0.5cm, 0.9cm, etc.; the fusion time is at least 0.5 h can specifically be 0.5h, 0.8h, 0.9h, 1.0h, 1.5h or 2h, etc., which is not limited here.
  • step S40 the aggregate is subjected to carbon coating treatment to obtain the negative electrode material.
  • the negative electrode material of this embodiment may not be coated with carbon, and in this case, step S40 may be omitted.
  • the step of carbon coating treatment includes: mixing the aggregate with a second carbon source, and performing secondary heat treatment to form a carbon layer on the surface of the aggregate.
  • the second carbon source includes sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, polyethylene glycol, At least one of vinylidene fluoride, polyacrylonitrile, polyvinyl chloride and asphalt.
  • the mass ratio of the aggregate to the second carbon source is (20-100):(10-120); specifically, the mass ratio of the aggregate to the second carbon source is 100:25, 100:35 , 100:45, 100:55, 100:65, etc., of course, can also be other values within the above range, which are not limited here.
  • the step of carbon coating treatment includes: mixing the second precursor with the second carbon source, and performing secondary heat treatment to A carbon layer is formed on the surface of the second precursor.
  • the mass ratio of the second precursor to the second carbon source is (30-100):(10-70).
  • the mass ratio of the second precursor to the second carbon source is 50:25, 100:20, 100:35, 100:45, 100:55, 100:65, etc.
  • it can also be other values within the above range, It is not limited here.
  • the temperature of the secondary heat treatment is 600°C-1200°C, such as 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, etc.
  • the temperature of the secondary heat treatment is 600°C to 1000°C.
  • the time for the secondary heat treatment is 1 h to 10 h, for example, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, or 10 h.
  • the heating rate during the secondary heat treatment is 1°C/min to 30°C/min, specifically 1°C/min, 5°C/min, 10°C/min, 15°C/min, 20°C/min min, 25°C/min or 30°C/min, etc.
  • the temperature increase rate during the secondary heat treatment is 1° C./min to 15° C./min.
  • a protective gas is passed through the secondary treatment process, and the protective gas includes at least one of nitrogen, helium, neon, argon, and krypton.
  • the mixing method may include magnetic stirring, mechanical stirring, ultrasonic dispersion, grinding dispersion, and the like.
  • the negative electrode material in this embodiment may not be coated with carbon, and is not limited to the above two methods of carbon coating.
  • At least one of crushing, sieving and demagnetization is further performed; preferably, after the secondary heat treatment, crushing, sieving and demagnetization are also performed sequentially.
  • the pulverization method is any one of a mechanical pulverizer, a jet pulverizer, and a low-temperature pulverizer.
  • the screening method is any one of a fixed screen, a drum screen, a resonance screen, a roller screen, a vibrating screen, and a chain screen, and the screening mesh is ⁇ 500 mesh.
  • the screening mesh The mesh number can be 500 mesh, 600 mesh, 700 mesh, 800 mesh, etc., and the particle size of the negative electrode material is controlled within the above range, which is conducive to the improvement of the cycle performance of the negative electrode material.
  • the demagnetization equipment is any one of permanent magnet drum magnetic separator, electromagnetic iron remover, and pulsating high-gradient magnetic separator.
  • the purpose of demagnetization is to finally control the magnetic content of the negative electrode material and avoid The discharge effect of substances on lithium-ion batteries and the safety of batteries during use.
  • the present application also provides a lithium ion battery, including the above-mentioned negative electrode material.
  • the target area ratio C is obtained by the following test methods:
  • the first precursor is placed in a heat treatment furnace, and the temperature is raised to 890° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 4 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 400r/min; the width of the tool gap of the fusion machine used for mechanical fusion is 0.8cm; the mechanical fusion time is 2h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 64.6:35.4.
  • the median particle size of the negative electrode material was 13.2 ⁇ m, the specific surface area was 3.5 m 2 /g, and the average thickness of the carbon layer was 350 nm.
  • the target area ratio C in the negative electrode material is 15%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.0%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 155 MPa.
  • Fig. 2 is the scanning electron microscope (SEM) picture of the negative electrode material prepared by the embodiment 1 of the present application
  • Fig. 3 is the XRD figure of the negative electrode material prepared by the embodiment 1 of the present application, as shown in Fig. 3, there is silicon peak in the negative electrode material bit.
  • the first precursor is placed in a heat treatment furnace, the temperature is raised to 850° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 4 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 600r/min; the width of the tool gap of the fusion machine is 0.7cm; the fusion time is 1.5h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 61.6:38.4.
  • the median particle size of the negative electrode material was 12.2 ⁇ m, the specific surface area was 3.1 m 2 /g, and the average thickness of the carbon layer was 380 nm.
  • the target area ratio C in the negative electrode material is 35%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 1.6%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 231MPa.
  • the first precursor is placed in a heat treatment furnace, and the temperature is raised to 800° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 4 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 400r/min; the width of the tool gap of the fusion machine is 0.6cm; the fusion time is 2.5h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 57.1:42.9.
  • the median particle size of the negative electrode material was 10.2 ⁇ m, the specific surface area was 2.1 m 2 /g, and the average thickness of the carbon layer was 580 nm.
  • the target area ratio C in the negative electrode material is 45%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.3%.
  • a nanoindentation instrument was used to test the negative electrode material particles, and the average compressive hardness of the negative electrode material was 123MPa.
  • the first precursor is placed in a heat treatment furnace, and the temperature is raised to 820° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 4 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 480r/min; the width of the tool gap of the fusion machine is 0.6cm; the fusion time is 3h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 49.4:50.6.
  • the median particle size of the negative electrode material was 10.5 ⁇ m, the specific surface area was 2.0 m 2 /g, and the average thickness of the carbon layer was 680 nm.
  • the target area ratio C in the negative electrode material is 52%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 3.1%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 301MPa.
  • the first precursor is placed in a heat treatment furnace, and the temperature is raised to 720° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 3 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 580r/min; the width of the tool gap of the fusion machine is 0.5cm; the fusion time is 2h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 47.2:52.8.
  • the median particle size of the negative electrode material was 13.5 ⁇ m, the specific surface area was 1.9 m 2 /g, and the average thickness of the carbon layer was 850 nm.
  • the target area ratio C in the negative electrode material is 38%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.4%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 266MPa.
  • the first precursor is placed in a heat treatment furnace, and the temperature is raised to 790° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 3 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 540r/min; the width of the tool gap of the fusion machine is 0.8cm; the fusion time is 2h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes an aggregate and a carbon layer coated on the surface of the aggregate.
  • the aggregate includes nano-Ge powder and carbon material, and the mass ratio of Ge powder and carbon material is 70.8:29.2.
  • the median particle size of the negative electrode material was 14.5 ⁇ m, the specific surface area was 4.9 m 2 /g, and the average thickness of the carbon layer was 310 nm.
  • the target area ratio C in the negative electrode material is 65%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.8%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 89MPa.
  • the first precursor is placed in a heat treatment furnace, and the temperature is raised to 890° C. by passing nitrogen gas, and a heat treatment is performed, and the temperature is kept for 2 hours to obtain the second precursor.
  • the rotation speed of the fusion machine is 640r/min; the width of the tool gap of the fusion machine is 0.8cm; the fusion time is 4h, and aggregates are obtained.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano Sn powder and carbon materials, and the mass ratio of Sn powder and carbon materials is 63.5:36.5.
  • the median particle size of the negative electrode material was 11.5 ⁇ m, the specific surface area was 3.1 m 2 /g, and the average thickness of the carbon layer was 350 nm.
  • the target area ratio C in the negative electrode material is 75%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 1.4%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 117MPa.
  • Embodiment 8 is roughly the same as Embodiment 1, and its difference is:
  • the primary heat treatment temperature in step (2) is 1200°C.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 64.6:35.4.
  • the median particle size of the negative electrode material was 14.8 ⁇ m, the specific surface area was 3.7 m 2 /g, and the average thickness of the carbon layer was 400 nm.
  • the target area ratio C in the negative electrode material is 78%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.6%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 167MPa.
  • Embodiment 9 is substantially the same as Embodiment 1, the difference being that the secondary heat treatment temperature in step (4) is 600°C.
  • the negative electrode material prepared in this embodiment includes an aggregate and a carbon layer coated on the surface of the aggregate.
  • the aggregate includes silicon powder and carbon material, and the mass ratio of silicon powder and carbon material is 64.6:35.8.
  • the median particle size of the negative electrode material was 13.8 ⁇ m, the specific surface area was 3.1 m 2 /g, and the average thickness of the carbon layer was 420 nm.
  • the target area ratio C in the negative electrode material is 40%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 3.5%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 133MPa.
  • Embodiment 10 is substantially the same as Embodiment 1, the difference being that the secondary heat treatment step in step (4) is not performed.
  • the negative electrode material prepared in this embodiment includes aggregates, the aggregates include silicon powder and carbon material, and the mass ratio of silicon powder and carbon material is 64.1:32.8.
  • the median particle size of the negative electrode material was 14.5 ⁇ m, the specific surface area was 3.8 m 2 /g, and the average thickness of the carbon layer was 380 nm.
  • the target area ratio C in the negative electrode material is 26%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 6.7%.
  • a nanoindentation instrument was used to test the negative electrode material particles, and the average compressive hardness of the negative electrode material was 59MPa.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 64.8:35.2.
  • the median particle size of the negative electrode material was 13.8 ⁇ m, the specific surface area was 3.9 m 2 /g, and the average thickness of the carbon layer was 360 nm.
  • the target area ratio C in the negative electrode material is 16%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 9.6%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 95MPa.
  • the negative electrode material was prepared in the same manner as in Example 1, except that metal oxide (SiO) was added in step (1), and the mass ratio of SiO to silicon powder was 5:100.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials.
  • the mass ratio of silicon powder, SiO and carbon materials is 63.8:4.5:31.7.
  • the median particle diameter of the negative electrode material was 11.8 ⁇ m, the specific surface area was 3.5 m 2 /g, and the average thickness of the carbon layer was 320 nm.
  • the target area ratio C in the negative electrode material is 18%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.5%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 195MPa.
  • step (1) has also added the conductivity enhancer (single-walled carbon nanotube) that tensile strength is 59Gpa, the quality of single-walled carbon nanotube and silicon powder The ratio is 1.5:100.
  • the negative electrode material prepared in this embodiment includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano-silicon powder and carbon materials, and the mass ratio of silicon powder, single-walled carbon nanotubes and carbon materials is 64.8:1.1 : 34.1.
  • the median particle size of the negative electrode material was 10.4 ⁇ m, the specific surface area was 2.1 m 2 /g, and the average thickness of the carbon layer was 360 nm.
  • the target area ratio C in the negative electrode material is 18.8%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 2.9%.
  • a nanoindentation instrument was used to test the negative electrode material particles, and the average compressive hardness of the negative electrode material was 175MPa.
  • the negative electrode material was prepared in the same manner as in Example 1, except that the grinding and dispersion treatment was not performed in step (1).
  • the negative electrode material prepared in this example includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 60.8:38.2.
  • the median particle size of the negative electrode material was 10.4 ⁇ m, the specific surface area was 4.6 m 2 /g, and the average thickness of the carbon layer was 320 nm.
  • the target area ratio C in the negative electrode material is 2%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 6.8%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 48MPa.
  • the negative electrode material was prepared in the same manner as in Example 1, except that the fusion treatment was not performed in step (3).
  • the negative electrode material prepared in this example includes aggregates and a carbon layer coated on the surface of the aggregates.
  • the aggregates include nano silicon powder and carbon materials, and the mass ratio of silicon powder and carbon materials is 76.2:35.2.
  • the median particle size of the negative electrode material was 21.6 ⁇ m, the specific surface area was 6.9 m 2 /g, and the average thickness of the carbon layer was 680 nm.
  • the target area ratio C in the negative electrode material is 6%.
  • the negative electrode material particles were tested by mercury porosimetry, and the porosity of the negative electrode material was 13.9%.
  • the negative electrode material particles were tested with a nano-indentation instrument, and the average compressive hardness of the negative electrode material was 44MPa. Test Methods
  • the electrochemical cycle performance was tested by the following method: the prepared silicon-carbon composite negative electrode material, conductive agent and binder were dissolved in a solvent and mixed in a mass percentage of 94:1:5, and the solid content was controlled at 50%.
  • the copper foil current collector vacuum-dried to obtain the negative electrode sheet; then the ternary positive electrode sheet prepared by the traditional mature process, 1mol/L LiPF6/ethylene carbonate+dimethyl carbonate+methyl ethyl carbonate
  • the charge-discharge test of the lithium-ion battery is carried out on the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd., under normal temperature conditions, 0.2C constant current charge and discharge, and the charge-discharge voltage is limited to 2.75 ⁇ 4.2V, get the first reversible capacity, the first cycle charge capacity and the first cycle discharge capacity.
  • the first coulombic efficiency the discharge capacity of the first cycle / the charge capacity of the first cycle.
  • Porosity was measured by mercury intrusion porosimetry. The porosity is measured at least three times, and the arithmetic mean of the at least three times is used as the measurement result.
  • the physical meaning of the median particle size in this application is the particle size corresponding to when the cumulative particle size distribution percentage of the particles reaches 50%, which is tested by a Malvern particle size analyzer.
  • the Malvern Particle Size Analyzer uses the light scattering phenomenon of particles to comprehensively convert the particle size distribution of the measured particles according to the distribution of scattered light energy.
  • the compressive hardness is tested by a nano-indenter, and the indentation hardness test is carried out with a load of 0.6N and an indentation depth of 0.5 ⁇ m.
  • the specific surface area of the negative electrode material was tested by using a Mike specific surface area tester.
  • the tensile strength of the conductivity enhancer was tested using a tensile testing machine.
  • Figure 4 is the initial charge-discharge curve of the negative electrode material prepared in Example 1 of the present application.
  • the active material in the battery maintains an appropriate spacing, which effectively avoids the self-agglomeration of the active material, avoids the loss of electrical contact during the lithium intercalation process, enhances the combination of the active material and the carbon material, and then improves the electrochemical performance of the negative electrode material.
  • Figure 5 is the cycle performance curve of the negative electrode material prepared in Example 1 of the present application.
  • the negative electrode material has excellent cycle performance, and the capacity retention rate of 100 cycles is 93.1%, because the aggregate has a smaller High porosity, the electrolyte is not easy to penetrate into the inside of the aggregate, the aggregate structure is conducive to protecting the active material particles inside, can effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • the negative electrode materials prepared in Examples 1 to 10 include aggregates, wherein the aggregates include active materials and carbon materials, and the dispersion of the active materials is ensured by controlling the spacing of the active materials in the aggregates. It can prevent the active material from tending to agglomerate, and ensure the smooth carrier transport channel inside the aggregate. It can avoid the soft agglomeration of particles, keep the active material at an appropriate distance, and also facilitate the penetration of subsequent carbon materials, improve the binding force between the active material and carbon material, and then improve the electrochemical performance of the material; the aggregate has a small porosity, The electrolyte is also not easy to penetrate into the interior of the aggregate.
  • the aggregate structure is conducive to protecting the active material particles inside, which can effectively inhibit the volume expansion of the negative electrode material, reduce the expansion rate, and improve the battery cycle performance.
  • the primary heat treatment temperature is too high, and a small amount of inactive SiC material will be generated, so that the reversible capacity and the first coulombic efficiency of the negative electrode material will decrease.
  • the secondary heat treatment temperature is too low, the carbon source coated on the surface of the aggregate is not completely carbonized, the conductivity of the negative electrode material decreases, and the first Coulombic efficiency of the negative electrode material decreases.
  • the surface of the aggregate was not coated with carbon, and no carbon layer was formed, the conductivity of the negative electrode material decreased, and the first Coulombic efficiency decreased.
  • metal oxides were also added in the step of graded mixing of the active material, additives, first carbon source and solvent, so that the rigidity of the aggregate structure was improved, and the particle cycle stability was improved.
  • the pole piece expansion rate decreased after cycling.
  • a conductivity enhancer was also added in the step of graded mixing of the active material, additives, first carbon source and solvent, which can effectively improve the transport of carriers inside the aggregate and enhance The conductivity of the aggregate is improved, and the first Coulombic efficiency of the negative electrode material is improved. Moreover, the conductive enhancer can effectively improve the structural stability of the aggregate, improve the cycle stability of the particles, and reduce the expansion rate of the pole piece after cycle.
  • the raw materials in step (1) were not ground and dispersed, the mixing uniformity of the active material and the carbon material decreased, and the active material was not dispersed enough in the raw material, resulting in the aggregation of the negative electrode material.
  • the distance between them decreases obviously, the dispersion degree of the active material decreases, the active material tends to agglomerate, the carrier transport channel inside the aggregate is easily blocked, and the electrochemical performance of the material decreases.
  • the precursor in step (2) is not fused, the overall structure tends to be loose, the connection stability between the active material and the carbon material is poor, and the pores between the active material and the carbon material increase.
  • the structural strength of the aggregate decreases, the compressive strength decreases significantly, it is difficult to resist the stress change caused by the expansion effect of the active material, and the expansion rate increases.

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Abstract

本申请涉及负极材料领域，提供负极材料及其制备方法、锂离子电池，其中，负极材料包括聚集体，聚集体包括活性物质和碳材料，其中，负极材料的孔隙率≤10％，且负极材料中的目标区域比例C≥15％，其中，目标区域比例C通过以下的测试方法获得：将负极材料颗粒的SEM切面分割成面积为A×B的区域，其中A及B均≤1微米，统计单个负极材料颗粒的所有区域内的活性物质的分布情况，将活性物质之间的间距为10nm～300nm的区域的数量计为N1，将活性物质之间的间距小于10nm的区域和大于300nm的区域的总数量计为N2，单个负极材料颗粒的目标区域比例X定义为X＝N1/N2，C为任意5个所述负极材料颗粒的X值的算术平均值。本申请提供的负极材料能够有效抑制负极材料体积膨胀，提升电池循环性能。

Description

负极材料及其制备方法、锂离子电池
本申请要求于2021年09月03日提交中国专利局，申请号为2021110323875、申请名称为“负极材料及其制备方法、锂离子电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及负极材料技术领域，具体地讲，涉及负极材料及其制备方法、锂离子电池。
背景技术
现有的锂离子电池由于具备能量密度大、输出功率高、循环寿命长和环境污染小等优点而被广泛应用于电动汽车以及消费类电子产品中。为了提高电池能量密度，硅负极材料的研究和开发日趋成熟。但是负极材料脱嵌锂过程中体积膨胀较大，特别是硅负极材料在脱嵌锂过程中体积膨胀可以达到300％以上，在充放电过程中会粉化从集流体上掉落，使得负极活性材料与集流体之间失掉电接触，导致电化学性能变差，容量衰减、循环稳定性下降，难以得到商业应用。
因此，如何抑制负极材料的体积膨胀，提高材料的循环稳定性是目前急需解决的问题。
申请内容
鉴于此，本申请提供负极材料及其制备方法、锂离子电池，能够有效抑制负极材料体积膨胀，提升电池循环性能，该制备方法可降低制备成本。
第一方面，一种负极材料，所述负极材料包括聚集体，所述聚集体包括活性物质和碳材料，其中，所述负极材料的孔隙率≤10％，且所述负极材料中的目标区域比例C≥15％，
其中，所述目标区域比例C通过以下的测试方法获得：
将所述负极材料颗粒的SEM切面分割成面积为A×B的区域，其中A及B均≤1微米，统计单个所述负极材料颗粒的所有所述区域内的所述活性物质的分布情况，将所述活性物质之间的间距为10nm～300nm的区域的数量计为N1，将所述活性物质之间的间距小于10nm的区域和大于300nm的区域的总数量计为N2，单个所述负极材料颗粒的目标区域比例X定义为X＝N1/N2，C为任意5个所述负极材料颗粒的X值的算术平均值。
本实施方式的负极材料包括聚集体，聚集体包括活性物质、碳材料和导电增强剂。负极材料目标区域比例C≥15％，将目标区域比例C控制在此范围内，活性物质保持了适当的间距，有效避免了活性物质的自团聚，可以避免脱嵌锂过程中失去电接触，同时也有利于后续碳材料的渗透，增强活性物质与碳材料的结合，进而提高材料的电化学性能；聚集体具有较小的孔隙率，电解液也不容易渗透进聚集体内部，该聚集体结构有利于保护内部的活性物质颗粒，可以有效抑制负极材料体积膨胀，降低膨胀率， 提升电池循环性能。
一实施方式中，所述活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x＜2)、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种。
一实施方式中，所述活性物质的中值粒径为1nm至500nm。
一实施方式中，所述碳材料包括无定形碳、结晶碳及中间相碳微球中的至少一种。
一实施方式中，所述活性物质以及所述碳材料的质量比为(20～70)：(10～80)。
一实施方式中，所述聚集体还包括金属氧化物。
一实施方式中，所述金属氧化物分布于所述活性物质之间，所述活性物质和所述金属氧化物之间填充有所述碳材料。
一实施方式中，所述活性物质与所述金属氧化物之间具有孔隙，所述孔隙中填充有所述碳材料。
一实施方式中，所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种。
一实施方式中，所述金属氧化物呈片状和/或长条状。
一实施方式中，所述金属氧化物的长径比大于2。
一实施方式中，所述金属氧化物与所述活性物质的质量比为(1～20)：100。
一实施方式中，所述聚集体还包括导电增强剂。
一实施方式中，所述导电增强剂包括合金材料及导电碳中的至少一种。
一实施方式中，所述导电碳包括碳纳米管、碳纤维、石墨纤维中的至少一种。
一实施方式中，所述导电增强剂的电导率＞10 2S/m。
一实施方式中，所述导电增强剂呈片状和/或长条状，所述导电增强剂的长径比为2～3000。
一实施方式中，所述导电增强剂与所述活性物质的质量比为(0.1～10):100。
一实施方式中，所述导电增强剂的抗拉强度≥500MPa。
一实施方式中，所述负极材料还包括包覆于所述聚集体的至少部分表面的碳层。
一实施方式中，所述碳层的材料包括无定形碳。
一实施方式中，所述碳层的厚度为10nm至1500nm。
一实施方式中，所述负极材料的中值粒径为0.5μm～30μm。
一实施方式中，所述负极材料的比表面积≤10m 2/g。
一实施方式中，所述负极材料的耐压硬度≥50MPa。
一实施方式中，所述负极材料的孔隙率≤10％。
一实施方式中，所述聚集体密度满足以下关系：所述聚集体的测试密度与所述聚集体的平均密度的差值≤5％。
第二方面，本申请提供一种负极材料的制备方法，包括以下步骤：
将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散后除去所述溶剂得到第一前驱体；
对所述第一前驱体在600℃～1200℃进行一次热处理得到第二前驱体；及
对所述第二前驱体进行密实化处理，得到聚集体。
在上述方案中，将包含活性物质、第一碳源与溶剂的原料进行混合并充分分散，可以提高第一前驱体中活性物质的分散度，再将得到的第一前驱体在600℃～1200℃进行一次热处理得到第二前驱体，再将第二前驱体进行密实化处理，在密实化处理过程中，上述物质团聚形成聚集体，可以提高聚集体中活性物质的分散度，降低聚集体的孔隙率，整个制备过程简单，制备得到的负极材料可以有效抑制体积膨胀，降低膨胀率，提升电池循环性能。
一实施方式中，所述活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x＜2)、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种。
一实施方式中，所述第一碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯、沥青中的至少一种。
一实施方式中，所述第一碳源与所述活性物质的质量比为(5～40)：100；
一实施方式中，所述溶剂包括有机溶剂。
一实施方式中，所述有机溶剂包括甲醇、乙醇、乙二醇、丙醇、异丙醇、丙三醇、正丁醇、异丁醇及戊醇中的至少一种。
一实施方式中，所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了添加剂。
一实施方式中，所述添加剂包括表面活性剂、偶联剂中的至少一种。
一实施方式中，所述表面活性剂包括正十八酸、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、棕榈酸、十四烷酸、十一烷酸、十六烷基三甲基溴化胺及聚乙烯吡咯烷酮中的至少一种。
一实施方式中，所述偶联剂包括硅烷偶联剂，所述硅烷偶联剂包括γ-氨丙基三乙氧基硅烷、γ-缩水甘油醚氧丙基三甲氧基硅烷、γ-甲基丙烯酰氧基丙基三甲氧基硅烷。
一实施方式中，所述活性物质与所述添加剂的质量比为(15～120)：(1～10)。
一实施方式中，所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物。
一实施方式中，所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种。
一实施方式中，所述金属氧化物呈片状和/或长条状。
一实施方式中，所述金属氧化物的长径比大于2。
一实施方式中，所述金属氧化物与所述活性物质的质量比为(1～20)：100。
一实施方式中，所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂。
一实施方式中，所述导电增强剂与所述活性物质的质量比为(0.1～10)：100。
一实施方式中，所述导电增强剂包括合金材料及导电碳中的至少一种。
一实施方式中，所述导电碳包括碳纳米管、碳纤维、石墨纤维中的至少一种。
一实施方式中，所述导电增强剂的电导率＞10 2S/m。
一实施方式中，所述导电增强剂呈片状和/或长条状。
一实施方式中，所述导电增强剂的长径比为2～3000。
一实施方式中，所述充分分散的处理方式包括机械搅拌、超声分散、研磨分散中的至少一种。
一实施方式中，所述将包含活性物质、第一碳源和溶剂的原料进行混合采用分级混合的方式。
一实施方式中，所述将包含活性物质、第一碳源和溶剂的原料进行混合具体为：将所述活性物质与所述溶剂混合形成第一预混物，将所述第一碳源与所述溶剂混合形成第二预混物，再将所述第一预混物与所述第二预混物混合。
一实施方式中，所述制备第一前驱体步骤包括将活性物质、第一碳源和溶剂进行混合并充分分散后，进行干燥处理得到所述第一前驱体。
一实施方式中，所述干燥处理的温度为40℃～600℃，时间为1h～15h。
一实施方式中，所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理、及浸渍处理中的至少一种。
一实施方式中，所述的融合处理为机械融合。
一实施方式中，所述机械融合所用的融合机的转速为300r/min～3000r/min。
一实施方式中，所述机械融合所用的融合机刀具间隙宽度为0.01cm～0.9cm。
一实施方式中，所述机械融合时间至少为0.5h。
一实施方式中，所述一次热处理的时间为1h～10h。
一实施方式中，所述一次热处理过程通有保护性气体。
一实施方式中，所述保护性气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
一实施方式中，所述方法还包括对所述聚集体进行碳包覆处理。
一实施方式中，所述碳包覆处理的步骤包括：将第二前驱体与第二碳源进行混合、二次热处理。
一实施方式中，所述第二前驱体与所述第二碳源的质量比为(30～100)：(10～70)。
一实施方式中，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合、二次热处理。
一实施方式中，所述第二碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种。
一实施方式中，所述聚集体与所述第二碳源的质量比为(15～100)：(10～70)。
一实施方式中，所述二次热处理的温度为600℃～1200℃，所述二次热处理的时间为1h～10h。
一实施方式中，所述二次热处理过程通有保护性气体。
一实施方式中，所述保护性气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
第三方面，本申请提供一种锂离子电池，所述锂离子电池包括第一方面所述的负极材料或根据第二方面所述的制备方法制得的负极材料。
本申请的技术方案至少具有以下有益的效果：
本实施方式的负极材料包括聚集体，聚集体包括活性物质、碳材料和导电增强剂。负极材料目标区域比例C≥15％，在此范围内，活性物质保持了适当的间距，有效避免了活性物质的自团聚，可以避免脱嵌锂过程中失去电接触，同时也有利于后续碳材料的渗透，增强活性物质与碳材料的结合，进而提高材料的电化学性能；聚集体具有较小的孔隙率，电解液也不容易渗透进聚集体内部，该聚集体结构有利于保护内部的活性物质颗粒，可以有效抑制负极材料体积膨胀，降低膨胀率，提升电池循环性能。
其次，本申请提供的负极材料的制备方法，将包含活性物质、第一碳源与溶剂的原料进行混合并充分分散，可以提高第一前驱体中活性物质的分散度，再将得到的第一前驱体进行一次热处理得到第二前驱体，再将第二前驱体进行密实化处理，在密实化处理过程中，上述物质团聚形成聚集体，可以提高聚集体中活性物质的分散度，降低聚集体的孔隙率，整个制备过程简单，制备得到的负极材料可以有效抑制体积膨胀，降低膨胀率，提升电池循环性能。
本申请提供的制备方法，能够适用于扩大化生产，制备得到负极材料能够有效提高锂电池充放电循环的稳定性，有效降低负极材料的膨胀率。
附图说明
图1为本申请实施例提供的负极材料的制备方法的流程示意图；
图2为本申请实施例1制备的负极材料的扫描电子显微镜(SEM)图片；
图3为本申请实施例1制备的负极材料的XRD图；
图4为本申请实施例1制备的负极材料的首次充放电曲线；
图5为本申请实施例1制备的负极材料的循环性能曲线。
具体实施方式
以下所述是本申请实施例的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本申请实施例原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也视为本申请实施例的保护范围。
一实施方式的负极材料，负极材料包括聚集体，聚集体包括活性物质和碳材料，其中，负极材料的孔隙率≤10％，且负极材料中的目标区域比例C≥15％，
其中，目标区域比例C通过以下的测试方法获得：
将负极材料颗粒的SEM切面分割成面积为A×B的区域，其中A及B均≤1微米，统计单个负极材料颗粒的所有区域内的活性物质的分布情况，将活性物质之间的间距为10nm～300nm的区域的数量计为N1，将活性物质之间的间距小于10nm的区域和大于300nm的区域的总数量计为N2，单个负极材料颗粒的目标区域比例X定义为X＝N1/N2，C为任意5个负极材料颗粒的X值的算术平均值。
需要说明的是，如果某区域中既存在间距为10nm～300nm之间的活性物质，又存在间距小于10nm或大于300nm的活性物质，则将该区域的数量计入N1。
本实施方式的负极材料包括聚集体，聚集体包括活性物质和碳材料。负极材料目标区域比例C≥15％，在此范围内，活性物质保持了适当的间距，有效避免了活性物质的自团聚，可以避免脱嵌锂过程中失去电接触，同时也有利于后续碳材料的渗透，增强活性物质与碳材料的结合，进而提高材料的电化学性能；聚集体具有较小的孔隙率，电解液也不容易渗透进聚集体内部，该聚集体结构有利于保护内部的活性物质颗粒，可以有效抑制负极材料体积膨胀，降低膨胀率，提升电池循环性能。
负极材料的孔隙率≤10％，此时，负极材料的孔隙率较低，即其密实度很高，一方面有助于提高复合材料的能量密度，另一方面高密实度的材料即使表层被破坏，电解液也不容易渗透进聚集体内部，有利于保护内部的活性物质颗粒，减少电解液与活性物质的接触几率，从而有利于形成稳定的固体电解质膜；并且高密实化的聚集体具有较高的耐压硬度，能够对冲膨胀所带来的应力效应，提高负极材料的结构稳定性，可以有效抑制负极材料体积膨胀，降低膨胀率，提升电池循环性能。
在一些实施方式中，负极材料的孔隙率具体可以是10％、9％、9.5％、8％、8.5％、7.5％、7％、6.5％、6％或5％等等，当然也可以是上述范围内的其它值，在此不做限定。可以理解地，负极材料的孔隙率较低，即其密实度很高，有利于形成稳定的固体电解质膜，减少电解液与活性物质的接触。优选地，负极材料的孔隙率≤3％。
在一些实施方式中，负极材料的耐压硬度≥50MPa。具体的，负极材料的耐压硬度具体可以是50MPa、250MPa、300MPa、450MPa、500MPa、750MPa、900MPa、1150MPa、1200MPa或1250MPa等等，当然也可以是上述范围内的其它值，在此不做限定。因为其具有较强的刚性，粒子结构稳定性强，可以抵御一定的体积膨胀应力，从而降低膨胀，提升电池循环稳定性。优选地，负极材料的耐压硬度≥100MPa，更优选地，负极材料的耐压硬度≥200MPa。
在一些实施方式中，聚集体密度满足以下关系：聚集体的测试密度与聚集体的平均密度的差值≤5％。聚集体颗粒的密度与平均密度越接近，相差越小，说明颗粒内部的孔隙越少，越密实，有利于形成稳定的固体电解质膜，减少电解液与活性物质的接触。
具体地，聚集体密度计算如下：(ρ1-ρ2)/ρ2≤5％，其中ρ1为聚集体的测试密度，ρ2为聚集体的平均密度。
其中，ρ2为聚集体中各组分在聚集体的质量百分含量*各组分的理论密度的值的总和。
具体的示例中，当聚集体包括活性物质、导电增强剂和碳材料时，ρ2＝活性物质在聚集体中的质量百分含量*活性物质理论密度+导电增强剂在聚集体中的质量百分含量*导电增强剂理论密度+碳材料在聚集体中的质量百分含量*碳材料理论密度。
当聚集体包括活性物质、金属氧化物、导电增强剂和碳材料时，ρ2＝活性物质在聚集体中的质量百分含量*活性物质理论密度+金属氧化物在聚集体中的质量百分含量*金属氧化物理论密度+导电增强剂在聚集体中的质量百分含量*导电增强剂的理论密度+碳材料在聚集体中的质量百分含量*碳材料理论密度。
在一些实施方式中，活性物质指的是可以与锂反应，进行脱嵌锂的物质。
活性物质包括金属单质、金属氧化物及金属合金中的至少一种。进一步的，金属包括Li、Na、K、Sn、Ge、Si、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种。金属单质指的是上述金属单质，金属氧化物指的是上述金属的氧化物，金属合金指的是包含上述至少一种金属的合金，比如硅锂合金、硅镁合金等。
在一些实施方式中，活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x＜2)、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种。
在一些实施方式中，活性物质为颗粒，活性物质的中值粒径为1nm至500nm。具体可以是1nm、5nm、10nm、15nm、20nm、30nm、40nm、50nm、100nm、200nm、300nm、400nm或500nm等等，当然也可以是上述范围内的其他值，在此不做限定。通过多次试验发现，纳米级的活性物质，其表面能高，在充放电过程中容易发生团聚，颗粒的结构性强，可以抑制硅体积膨胀。但由于纳米级硅基活性粒子有较大的表面能，在充放电过程中容易发生团聚。活性物质的粒径过小，生产工艺成本高。优选地，活性物质的中值粒径为1nm～200nm，更优选为1nm-100nm。
在一些实施方式中，碳材料包括无定形碳、结晶碳及中间相碳微球中的至少一种。
在一些实施方式中，活性物质与碳材料的质量比为(20～70)：(10～80)。具体可以为20：10、20：20、20：30、20：50、20：60、20：80、40：10、40：50、40：80、50：70、50：80等等。当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，聚集体还包括金属氧化物，将金属氧化物与活性物质进行复合，可以降低活性物质的膨胀，提升长循环性能，且聚集体有更高的耐压硬度。
在一些实施方式中，在聚集体中，金属氧化物分布于活性物质之间，活性物质和金属氧化物之间填充有碳材料。
具体地，活性物质与金属氧化物之间具有孔隙，孔隙中填充有碳材料。可以理解地，通过活性物质与金属氧化物由于堆叠、聚集形成的孔隙结构，使得碳材料填充孔隙内，可以提高聚集体的结构稳定性，可以抵御一定的体积膨胀应力，降低膨胀。
在一些实施方式中，金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca或Zn中的至少一种；具体地，金属氧化物可以是SiO、GeO 2、SnO 2、ZnO、TiO 2、Fe 3O 4、MgO、SiO 2、CuO等等。选取的金属氧化物在嵌锂过程的体积膨胀变化率低于活性物质，因此，将金属氧化物与活性物质进行复合，可以降低活性物质的膨胀，提升长循环性能。
在一些实施方式中，金属氧化物呈片状和/或长条状。
在一些实施方式中，金属氧化物的长径比值大于2。需要说明的是，当金属氧化物为长条状时，长径比具体是指颗粒的长度与颗粒的粒径的比值；当金属氧化物为片状时，长径比具体是指片状金属氧化物的长度与宽度的比值。具体地，金属氧化物的长径比值可以是2、2.5、3、3.5、4、4.5、5、6、7、8、9、12、15、17、18、22等等，当然也可以是上述范围内的其他值，在此不做限定。根据多次试验发现，金属氧化物的长径比大于2时，可以提升金属氧化物与活性物质的物理结合力，从而更能缓冲活性物质的体积膨胀变化，提升循环性能。
在一些实施方式中，金属氧化物与活性物质的质量比为(1～20)：100。具体地， 金属氧化物与活性物质的质量比可以为1：100、1.5：100、2：100、3：100、4.5：100、5：100、6：100、7：100、8：100、9：100等等。当然也可以是上述范围内的其他值，在此不做限定。金属氧化物含量过高，导致材料的首次效率下降，金属氧化物含量过低，会导致其对聚集体结构的刚性下降，颗粒循环稳定性下降。
在一些实施方式中，聚集体还包括导电增强剂。
在一些实施方式中，导电增强剂的抗拉强度≥500MPa，负极材料中导电增强剂的分散度N≥1；其中，分散度N通过以下的测试方法获得：将负极材料颗粒的SEM切面分割成面积为A×B的区域，其中，A及B均≤1微米，统计单个负极材料颗粒的所有区域内的导电增强剂的分布情况，将存在导电增强剂之间的间距＜10nm的区域的数量统计为Na，将存在导电增强剂之间的间距均≥10nm的区域的数量统计为Nb，单个负极材料颗粒中导电增强剂的分散度C定义为C＝Nb/Na，N为任意5个负极材料颗粒的C值的算术平均值。导电增强剂均匀分散可以有效改善载流子在聚集体内部的传输，增强了聚集体的导电性，并且导电增强剂可以有效提高聚集体的结构稳定性，强化了聚集体的结构强度，能够避免活性物质膨胀效应带了的应力变化，维持聚集体的结构稳定性，从而提高材料的循环稳定性能，降低膨胀率。将导电增强剂的抗拉强度控制≥500MPa的范围内，导电增强剂具有较优异的机械性能，可以作为结构的支撑体增强材料的稳定性，通过控制导电增强剂之间的最小间距，可以使得导电增强剂之间能够填充活性物质，可以将导电增强剂作为结构的支撑体增强材料的稳定性，从而缓冲活性物质的体积膨胀变化，提升循环性能。
其中，导电增强剂的抗拉强度可以是500MPa、800MPa、1Gpa、5Gpa、10Gpa、25Gpa、30Gpa、45Gpa或50Gpa等等，当然也可以是上述范围内的其他值，在此不做限定。
其中，导电增强剂分布于聚集体的内部和/或表面。
在一些实施方式中，导电增强剂分布于活性物质之间，活性物质和导电增强剂之间填充有碳材料。可以理解地，通过将导电增强剂分布于活性物质中，可以提高活性物质的导电性，改善载流子在活性物质内的传输。
在一些实施方式中，碳材料与导电增强剂之间由于堆叠、聚集形成有孔隙，孔隙中填充有活性物质。可以理解地，碳材料与导电增强剂形成孔隙结构，使得活性物质孔隙内，可以提高聚集体的结构强度，可以通过该孔隙结构来抵御活性物质膨胀产生的应力变化，维持聚集体结构稳定性。
在一些实施方式中，导电增强剂包括合金材料及导电碳中的至少一种。当然，可以理解，任何其他抗拉强度≥500MPa的导电材料都可以作为导电增强剂。
在一些实施方式中，导电碳包括碳纳米管、碳纤维、石墨纤维中的至少一种。
在一些实施方式中，合金材料为电导率＞10 2S/m且抗拉强度≥500MPa的合金。
在一些实施方式中，合金材料包括硅合金、铝合金、铜合金、铝合金及锂合金中的至少一种。进一步的，硅合金包括镍硅合金、铁硅合金、铜硅合金、硅锰合金及铝硅合金中的至少一种。
在一些实施方式中，导电增强剂的电导率＞10 2S/m。具体地，导电增强剂的电导 率可以为100S/m、10 3S/m、10 4S/m、10 5S/m、10 8S/m等。此范围内的导电增强剂可有效改善载流子在聚集体内部的传输，增强了聚集体的导电性。
在一些实施方式中，导电增强剂呈片状和/或长条状。
在一些实施方式中，导电增强剂的长径比为2～3000。需要说明的是，当导电增强剂为长条状时，长径比具体是指颗粒的长度与颗粒的粒径的比值，这里的粒径指的是垂直于长条状导电增强剂长度方向的截面周缘上的两点之间的最大直线距离；当金属氧化物为片状时，长径比具体是指片状导电增强剂的长度与宽度的比值。具体地，导电增强剂的长径比值可以是2、30、46、150、360、670、800、900、1500、2000或3000等等，当然也可以是上述范围内的其他值，在此不做限定。根据多次试验发现，长径比在该范围内的导电增强剂，具有较优异的机械性能，可以作为结构的支撑体增强材料的稳定性，从而缓冲活性物质的体积膨胀变化，提升循环性能。
在一些实施方式中，导电增强剂的抗拉强度≥500MPa。需要说明的是，当导电增强剂的抗拉强度过低时，导电增强剂难以抵御活性物质膨胀产生的应力变化，难以维持聚集体结构稳定性，不利于提高材料的循环性能。具体地，导电增强剂的抗拉强度可以是500M pa、520M pa、550M pa、580M pa、600M pa、650M pa、700M pa、750Mpa或800M pa等等，当然也可以是上述范围内的其他值，在此不做限定。根据多次试验发现，将导电增强剂的抗拉强度控制在上述范围内，导电增强剂具有较优异的机械性能，可以作为结构的支撑体增强材料的稳定性，从而缓冲活性物质的体积膨胀变化，提升循环性能。
在一些施方式中，导电增强剂与活性物质的质量比为(0.1～10)：100。具体可以为0.1：100、0.5：100、0.8：100、1：100、2：100、3：100、5：100、6：100、7：100、8：100、10：100等等。当然也可以是上述范围内的其他值，在此不做限定。
进一步地，负极材料还包括包覆于聚集体的至少部分表面的碳层。优选地，碳层分布于聚集体的表面。
在一些实施方式中，碳层包括无定形碳。
在一些实施方式中，碳层的厚度为10nm至1500nm。可以理解地，包覆聚集体表面的碳层能够减少活性物质与电解液接触，减少钝化膜生成，提升电池可逆电容量。
具体地，碳层的厚度可以是10nm、50nm、180nm、200nm、350nm、400nm、550nm、700nm、850nm、900nm、1050nm、1200nm或1500nm等等，当然也可以是上述范围内的其他值，在此不做限定。碳层过厚，碳占比过高，不利于获得高比容量的复合材料；碳层过薄，不利于增加负极材料的导电性且对材料的体积膨胀抑制性能较弱，导致长循环性能价差。优选地，碳层的厚度为50nm～800nm；更优选地，碳层的厚度为100nm～500nm。
需要说明的是，在一些实施例中，聚集体表面包覆碳层后的负极材料的孔隙率≤10％，耐压硬度≥50MPa。负极材料整体孔隙率和耐压硬度保持在这个范围可以进一步提升负极材料的性能。
在一些实施方式中，负极材料的中值粒径为0.5μm～30μm。具体可以是0.5μm、1μm、5μm、8μm、10μm、13μm、15μm、18μm、20μm、25μm或30μm等等，当然也 可以是上述范围内的其他值，在此不做限定。可以理解地，负极材料的中值粒径控制在上述范围内，有利于负极材料循环性能的提升。
在一些实施方式中，负极材料的比表面积为≤10m 2/g。具体可以是10m 2/g、8m 2/g、7m 2/g、5m 2/g、3m 2/g、2m 2/g、1m 2/g或0.5m 2/g等等，当然也可以是上述范围内的其他值，在此不做限定。可以理解地，负极材料的比表面积控制在上述范围内，有利于抑制体积膨胀，有利于负极材料循环性能的提升。
需要说明的是，上述各个实施方式的负极材料在不相互矛盾的情况下，可以任意进行组合，比如聚集体的耐压硬度、孔隙率与密度进行组合限定等。
另一方面，本申请提供一种负极材料的制备方法，如图1所示，方法包括以下步骤：
步骤S10，将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散后除去溶剂得到第一前驱体；
步骤S20，对第一前驱体在600℃～1200℃进行一次热处理得到第二前驱体；及
步骤S30，对第二前驱体进行密实化处理，得到聚集体。
该实施方式的制备方法，将包含活性物质、第一碳源与溶剂的原料进行混合并充分分散，可以提高第一前驱体中活性物质的分散度，再将第一前驱体在600℃～1200℃进行一次热处理得到第二前驱体，再将第二前驱体进行密实化处理，在密实化处理过程中，上述物质团聚形成聚集体，可以提高聚集体中活性物质的分散度，降低聚集体的孔隙率，整个制备过程简单，制备得到的负极材料可以有效抑制体积膨胀，降低膨胀率，提升电池循环性能。
以下结合实施例具体介绍本申请的制备方法：
步骤S10，将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散后除去溶剂得到第一前驱体。
在一些实施方式中，将包含活性物质、第一碳源和溶剂的原料进行混合的步骤是采用分级混合的方式。具体的，可以将活性物质与溶剂混合形成第一预混物，将第一碳源与溶剂混合形成第二预混物，然后将第一预混物与第二预混物混合，以实现分级混合。根据活性物质、第一碳源和溶剂的具体成分按照分级混合原则选取合适的分级混合操作使得活性材料充分分散，以实现最终负极材料中目标区域比例C≥15％。
在一些实施方式中，充分分散的处理方式包括机械搅拌、超声分散、研磨分散中的至少一种。当然，可以理解的是，充分分散不限于采用上述方式，任何可以将活性材料充分分散，以实现最终负极材料中目标区域比例C≥15％的方式都可以。
在一些实施方式中，活性物质指的是可以与锂反应，进行脱嵌锂的物质。
活性物质包括金属单质、金属氧化物及金属合金中的至少一种。进一步的，金属包括Li、Na、K、Sn、Ge、Si、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种。
在一些实施方式中，活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x＜2)、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种。
在一些实施方式中，活性物质可以是上述金属单质，进一步的活性物质具体可以 是Si、Sn、Ge、Al。在另外的一些实施方式中，活性物质也可以是至少两种上述金属形成的合金，比如硅锂合金、硅镁合金等。在另外的一些实施例中，活性物质还可以为上述金属的氧化物，比如氧化亚硅。当然，需要说明的是，在一些情况下，活性物质包括金属单质、金属合金和金属氧化物中的至少两种。
在一些实施方式中，活性物质为颗粒，活性物质的中值粒径为1nm至500nm。具体可以是1nm、5nm、10nm、15nm、20nm、30nm、40nm、50nm、100nm、200nm、300nm、400nm或500nm等等，当然也可以是上述范围内的其他值，在此不做限定。通过多次试验发现，纳米级的活性物质，颗粒的结构性强，可以抑制活性粒子体积膨胀。但由于纳米级活性粒子有较大的表面能，在充放电过程中容易发生团聚，并且活性物质的粒径过小，生产工艺成本高。优选地，活性物质的中值粒径为1nm～200nm，更优选为1nm-100nm。
在一些实施方式中，第一碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯、沥青中的至少一种。
在一些实施方式中，溶剂包括有机溶剂；有机溶剂包括甲醇、乙醇、乙二醇、丙醇、异丙醇、丙三醇、正丁醇、异丁醇及戊醇中的至少一种。
在一些实施方式中，将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中的还加入了添加剂。其中，添加剂可以有效增强活性物质与第一碳源的连接稳定性，从而形成牢固的体系，降低极片膨胀率。
在一些实施方式中，第一碳源与活性物质的质量比为(5～40)：100；具体可以是5:100、10:100、15:100、20:100、25:100、30:100、35:100、38:100或40:100等。第一碳源与活性物质质量比值不宜太高，即第一碳源的含量不宜太高，不利于形成高孔隙率的前驱体，影响后续处理。
在一些实施方式中，添加剂包括表面活性剂、偶联剂中的至少一种。
表面活性剂包括正十八酸、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、棕榈酸、十四烷酸、十一烷酸、十六烷基三甲基溴化胺及聚乙烯吡咯烷酮中的至少一种。
偶联剂包括硅烷偶联剂，硅烷偶联剂包括γ-氨丙基三乙氧基硅烷、γ-缩水甘油醚氧丙基三甲氧基硅烷、γ-甲基丙烯酰氧基丙基三甲氧基硅烷。
在一些实施方式中，将包含活性物质、添加剂、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂。
在一些实施方式中，导电增强剂包括合金材料及导电碳中的至少一种。
在一些实施方式中，导电碳包括碳纳米管、碳纤维、石墨纤维中的至少一种。
在一些实施方式中，导电增强剂的电导率＞10 2S/m；具体地，导电增强剂的电导率可以为100S/m、10 3S/m、10 4S/m、10 5S/m、10 8S/m等。
在一些实施方式中，导电增强剂呈片状和/或长条状。
在一些实施方式中，导电增强剂的长径比为2～3000。需要说明的是，当导电增强剂为长条状时，长径比具体是指颗粒的长度与颗粒的粒径的比值，这里的粒径指的是 垂直于长条状导电增强剂长度方向的截面周缘上的两点之间的最大直线距离；当导电增强剂为片状时，长径比具体是指片状导电增强剂的长度与宽度的比值。具体地，导电增强剂的长径比值可以是2、30、46、150、360、670、800、900、1500、2000或3000等等，当然也可以是上述范围内的其他值，在此不做限定。根据多次试验发现，长径比在该范围内的导电增强剂，具有较优异的机械性能，可以作为结构的支撑体增强材料的稳定性，从而缓冲活性物质的体积膨胀变化，提升循环性能。
在一些实施方式中，导电增强剂与活性物质的质量比为(0.1～10)：100。具体地，导电增强剂与活性物质的质量比为0.1：100、0.5：100、1：100、2：100、2.6：100、3：100、3.5：100、4：100、4.8：100、6：100、7：100、8.5：100或10：100等。当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，将包含活性物质、添加剂、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物。
在一些实施方式中，金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种。
在一些实施方式中，金属氧化物呈片状和/或长条状。
在一些实施方式中，金属氧化物的长径比大于2。
在一些实施方式中，金属氧化物与活性物质的质量比为(1～20)：100。具体地，金属氧化物与活性物质的质量比可以为1：100、1.5：100、2：100、3：100、4.5：100、5：100、6：100、7：100、8：100、10：100、15:100、20:100等等。当然也可以是上述范围内的其他值，在此不做限定。金属氧化物含量过高，导致材料的首次效率下降，金属氧化物含量过低，会导致其对聚集体结构的刚性下降，负极材料循环稳定性下降。
在一些实施方式中，充分分散处理包括机械搅拌、超声分散及研磨分散中的至少一种。优选地，采用研磨分散，从而使得活性物质能够分散开，避免活性物质团聚在一起，并且可以使得活性物质分散为较小的纳米颗粒。优选地，通过采用湿法球磨，湿法球磨分散时间可以控制在0.5h～10h，通过充分研磨可以使得组分混合更加均匀，使得活性物质颗粒粒径达到1nm～500nm。
在一些实施方式中，将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散后除去溶剂得到第一前驱体，去除溶剂的方式包括干燥处理。
在一些实施方式中，干燥处理的温度为40℃～600℃，具体可以是40℃、50℃、80℃、100℃、120℃、250℃、380℃、400℃、500℃、580℃或600℃等等，干燥处理的时间为1h～15h，具体可以是1h、3h、5h、7h、9h、10h、12h或15h等等，干燥处理方式例如可以是炉内烘干、冷冻干燥、搅拌蒸干、喷雾干燥等，本实施例中的干燥处理可以尽可能地将前驱体溶液中的溶剂去除。
干燥后的第一前驱体还可以进行分散，分散可以为研磨分散，分散时间为0.5h-9h，具体可以是0.5h、1.5h、2.5h、3.5h、4.5h、5.5h、7.5h或9h等等，本实施例中的研磨分散，控制分散后的粒度大小。
在一些实施方式中，在对干燥后的第一前驱体进行分散过程中还可以加入第二碳源，第一前驱体与第二碳源的质量比例为(10～80)：10。分散后进行二次干燥获得碳 包覆的第一前驱体。
步骤S20，对第一前驱体进行一次热处理得到第二前驱体。
在一些实施方式中，一次热处理的方式例如可以是真空烧结、热压烧结或者常压烧结。
在一些实施方式中，一次热处理的温度为600℃～1200℃，例如可以是600℃、700℃、800℃、900℃、1000℃、1100℃、1200℃等。优选地，一次热处理的温度为600℃～1000℃。
在一些实施方式中，一次热处理的时间1h～10h，例如可以是1h、2h、3h、4h、5h、6h、7h、8h、9h或10h等。
热处理时的升温速率为1℃/min～30℃/min，具体可以是1℃/min、5℃/min、10℃/min、15℃/min、20℃/min、25℃/min或30℃/min等等。例如可以是，优选地，热处理时的升温速率为1℃/min～15℃/min。
热处理过程通有保护性气体，保护性气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
步骤S30，对第二前驱体进行密实化处理，得到聚集体。通过密实化处理，以使得得到的聚集体的孔隙率≤10％。
在一些实施方式中，密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理及浸渍处理中的至少一种。
在一些实施方式中，融合处理为机械融合。利用对前驱体进行融合处理，提高负极材料的耐压硬度，再进行一次热处理，增强颗粒结构的稳定性，同时可以增强活性物质与第一碳源之间的连接稳定性，降低孔隙率。当然，在其他的实施方式中，还可以采用其他方法进行密实化处理，比如模压、等静压、浸渍等工艺，只要能使得聚集体的孔隙率≤10％即可。
在一些实施方式中，聚集体的耐压硬度≥50MPa，聚集体的耐压硬度具体可以是50MPa、250MPa、300MPa、450MPa、500MPa、750MPa、900MPa、1150MPa、1200MPa或1250MPa等等，当然也可以是上述范围内的其它值，在此不做限定。因为其具有较强的刚性，粒子结构稳定性强，可以抵御一定的体积膨胀应力，从而降低膨胀，提升电池循环稳定性。优选地，聚集体的耐压硬度≥100MPa，更优选地，聚集体的耐压硬度≥200MPa。
在一些实施方式中，最终负极材料的孔隙率≤10％，负极材料的耐压硬度≥50MPa，此时可以根据最终碳包覆层的情况控制聚集体的孔隙率和耐压强度，以最终使负极材料的孔隙率和耐压强度达到目标值。
在一些实施方式中，融合时，融合机的转速为300r/min～3000r/min，具体可以是300r/min、1000r/min、1500r/min、2000r/min、2500r/min或3000r/min等等，融合机刀具间隙宽度为0.01cm～0.9cm，具体可以是0.01cm、0.05cm、0.1cm、0.15cm、0.2cm、0.25cm、0.3cm、0.5cm、0.9cm等等；融合时间至少为0.5h，具体可以是0.5h、0.8h、0.9h、1.0h、1.5h或2h等等，在此不做限定。
步骤S40，将聚集体进行碳包覆处理，得到负极材料。
需要说明的是，本实施方式的负极材料可以不进行碳包覆，此时，步骤S40可以 省略。在一些实施方式中，碳包覆处理的步骤包括：将聚集体与第二碳源进行混合、二次热处理，以在聚集体表面形成碳层。
在一些实施方式中，第二碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种。
在一些实施方式中，聚集体与第二碳源的质量比为(20～100)：(10～120)；具体地，聚集体与第二碳源的质量比为100:25、100:35、100:45、100:55、100:65等等，当然也可以是上述范围内的其他值，在此不做限定。
在另一些实施方式中，还可以采用其他方式对聚集体进行碳包覆，具体地，碳包覆处理的步骤包括：将第二前驱体与第二碳源进行混合、二次热处理，以在第二前驱体的表面形成碳层。
在一些实施方式中，第二前驱体与第二碳源的质量比为(30～100)：(10～70)。第二前驱体与第二碳源的质量比为50:25、100:20、100:35、100:45、100:55、100:65等等，当然也可以是上述范围内的其他值，在此不做限定。
在一些实施方式中，二次热处理的温度为600℃～1200℃，例如可以是600℃、700℃、800℃、900℃、1000℃、1100℃、1200℃等。优选地，二次热处理的温度为600℃～1000℃。
在一些实施方式中，二次热处理的时间1h～10h，例如可以是1h、2h、3h、4h、5h、6h、7h、8h、9h或10h等。
在一些实施方式中，二次热处理时的升温速率为1℃/min～30℃/min，具体可以是1℃/min、5℃/min、10℃/min、15℃/min、20℃/min、25℃/min或30℃/min等等。例如可以是，优选地，二次热处理时的升温速率为1℃/min～15℃/min。
在一些实施方式中，二次处理过程通有保护性气体，保护性气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
在一些实施方式中，混合方式可以包括磁力搅拌、机械搅拌、超声分散、研磨分散等等。
需要说明的是，本实施方式的负极材料可以不进行碳包覆，且不限于上述两种碳包覆的方法。
在一些实施方式中，二次热处理后，还进行粉碎、筛分和除磁中的至少一种；优选地，二次热处理后，还依次进行粉碎、筛分和除磁。
在一些实施方式中，粉碎方式为机械式粉碎机、气流粉碎机、低温粉碎机中任意一种。
在一些实施方式中，筛分的方式为固定筛、滚筒筛、共振筛、滚轴筛、振动筛、链条筛中任意一种，筛分的目数为≥500目，具体地，筛分的目数可以是500目、600目、700目、800目等等，负极材料的粒径控制在上述范围内，有利于负极材料循环性能的提升。
在一些实施方式中，除磁的设备为永磁筒式磁选机、电磁除铁机、脉动高梯度磁选机中任意一种，除磁是为了最终控制负极材料的磁性物质含量，避免磁性物质对锂离子电池的放电效果以及电池在使用过程中的安全性。
本申请还提供一种锂离子电池，包括上述的负极材料。
下面分多个实施例对本申请实施例进行进一步的说明。其中，本申请实施例不限定于以下的具体实施例。在不变主权利的范围内，可以适当的进行变更实施。
目标区域比例C通过以下的测试方法获得：
将负极材料颗粒的SEM切面分割成面积为A×B的区域，其中A及B均≤1微米，统计单个负极材料颗粒的所有区域内的活性物质的分布情况，将活性物质之间的间距10nm～300nm的区域数计为N1，将活性物质之间的间距小于10nm的区域和大于300nm的区域总数计为N2，单个负极材料颗粒的目标区域比例X定义为X＝N1/N2，C为任意5个负极材料颗粒的X值算术平均值。
实施例1
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为100nm的硅粉、烷基酚聚氧乙烯醚和酚醛树脂按照质量比50：3.6：16.4加入到乙二醇溶液中，超声分散60min得到分散溶液，再将分散溶液置于球磨机中研磨分散6小时，得到第一前驱体溶液，然后进行冷冻干燥处理，获得第一前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至890℃，进行一次热处理，保温4h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为400r/min；机械融合所用的融合机刀具间隙宽度为0.8cm；机械融合时间为2h，获得聚集体。
(4)将聚集体与蔗糖按照质量比80：89的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在850℃条件下进行二次热处理，保温4h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为64.6：35.4。
负极材料的中值粒径为13.2μm，比表面积为3.5m 2/g，碳层的平均厚度为350nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为15％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.0％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为155MPa。
图2为本申请实施例1制备的负极材料的扫描电子显微镜(SEM)图片，图3为本申请实施例1制备的负极材料的XRD图，如图3所示，负极材料中存在硅峰峰位。
实施例2
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为40nm的硅粉、γ-氨丙基三乙氧基硅烷和酚醛树脂按照质量比60：2.6：17.4加入到乙二醇溶液中，超声分散60min得到分散溶液，再将分散溶液置于球磨机中研磨分散6小时，得到第一前驱体溶液，然后进行冷冻干燥处理，获得第 一前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至850℃，进行一次热处理，保温4h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为600r/min；融合机刀具间隙宽度为0.7cm；融合时间为1.5h，获得聚集体。
(4)将聚集体与沥青按照质量比70：64的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在850℃条件下进行二次热处理，保温4h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为61.6：38.4。
负极材料的中值粒径为12.2μm，比表面积为3.1m 2/g，碳层的平均厚度为380nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为35％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为1.6％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为231MPa。
实施例3
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为30nm的硅粉、十二烷基苯磺酸钠和柠檬酸按照质量比45：4.6：14.4加入到乙二醇溶液中，超声分散40min得到分散溶液，再将分散溶液置于球磨机中研磨分散6小时，得到前驱体溶液，然后进行冷冻干燥处理，获得前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至800℃，进行一次热处理，保温4h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为400r/min；融合机刀具间隙宽度为0.6cm；融合时间为2.5h，获得聚集体。
(4)将聚集体与沥青按照质量比40:54的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在850℃条件下进行二次热处理，保温2h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为57.1：42.9。
负极材料的中值粒径为10.2μm，比表面积为2.1m 2/g，碳层的平均厚度为580nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为45％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.3％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为123MPa。
实施例4
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为80nm的硅粉、十一烷酸和果糖按照质量比40：2.6：7.4加入 到丁醇溶液中，超声分散60min得到分散溶液，再将分散溶液置于球磨机中研磨分散8小时，得到第一前驱体溶液，然后进行喷雾干燥处理，获得第一前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至820℃，进行一次热处理，保温4h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为480r/min；融合机刀具间隙宽度为0.6cm；融合时间为3h，获得聚集体。
(4)将聚集体与酚醛树脂按照质量比38:63的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在880℃条件下进行二次热处理，保温2h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为49.4：50.6。
负极材料的中值粒径为10.5μm，比表面积为2.0m 2/g，碳层的平均厚度为680nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为52％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为3.1％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为301MPa。
实施例5
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为40nm的硅粉、γ-甲基丙烯酰氧基丙基三甲氧基硅烷和沥青按照质量比46：4.5：13.5加入到丁醇溶液中，超声分散60min得到分散溶液，再将分散溶液置于球磨机中研磨分散4小时，得到第一前驱体溶液，然后进行喷雾干燥处理，获得第一前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至720℃，进行一次热处理，保温3h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为580r/min；融合机刀具间隙宽度为0.5cm；融合时间为2h，获得聚集体。
(4)将聚集体与酚醛树脂按照质量比58:63的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在880℃条件下进行二次热处理，保温2h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为47.2：52.8。
负极材料的中值粒径为13.5μm，比表面积为1.9m 2/g，碳层的平均厚度为850nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为38％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.4％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为266MPa。
实施例6
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为40nm的Ge粉、正十八酸和葡萄糖按照质量比46：4.5：9.5加入到丙醇溶液中，超声分散80min得到分散溶液，再将分散溶液置于球磨机中研磨分散4小时，得到第一前驱体溶液，然后进行喷雾干燥处理，获得第一前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至790℃，进行一次热处理，保温3h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为540r/min；融合机刀具间隙宽度为0.8cm；融合时间为2h，获得聚集体。
(4)将聚集体与酚醛树脂按照质量比88:70的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在980℃条件下进行二次热处理，保温2h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米Ge粉及碳材料，Ge粉及碳材料的质量比为70.8：29.2。
负极材料的中值粒径为14.5μm，比表面积为4.9m 2/g，碳层的平均厚度为310nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为65％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.8％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为89MPa。
实施例7
本实施例的负极材料的制备方法，包括以下步骤：
(1)将中值粒径为80nm的Sn粉、十六烷基三甲基溴化胺和酚醛树脂按照质量比66：4.5：15.5加入到乙醇溶液中，超声分散90min得到分散溶液，再将分散溶液置于球磨机中研磨分散5小时，得到第一前驱体溶液，然后进行喷雾干燥处理，获得第一前驱体。
(2)将第一前驱体置于热处理炉中，通入氮气升温至890℃，进行一次热处理，保温2h，得到第二前驱体。
(3)将第二前驱体放置融合机中，融合机的转速为640r/min；融合机刀具间隙宽度为0.8cm；融合时间为4h，获得聚集体。
(4)将聚集体与沥青按照质量比100:75的比例进行混合，随后将混合后的物料放置到高温箱式炉中，通入氮气，在920℃条件下进行二次热处理，保温2h后，进行粉碎、通过500目筛过筛，获得负极材料。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米Sn粉及碳材料，Sn粉及碳材料的质量比为63.5：36.5。
负极材料的中值粒径为11.5μm，比表面积为3.1m 2/g，碳层的平均厚度为350nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为75％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为1.4％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为117MPa。
实施例8
实施例8与实施例1大致相同，其不同的是：
(1)将中值粒径为100nm的硅粉分散于乙二醇溶液中，并将烷基酚聚氧乙烯醚和酚醛树脂分散于乙二醇溶液中，在搅拌状态下，将上述液体混合，超声分散10min得到分散溶液，再将分散溶液置于球磨机中研磨分散6小时，得到第一前驱体溶液，然后进行冷冻干燥处理，获得第一前驱体。
步骤(2)中的一次热处理温度为1200℃。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为64.6：35.4。
负极材料的中值粒径为14.8μm，比表面积为3.7m 2/g，碳层的平均厚度为400nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为78％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.6％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为167MPa。
实施例9
实施例9与实施例1大致相同，其区别在于，步骤(4)中的二次热处理温度为600℃。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括硅粉及碳材料，硅粉及碳材料的质量比为64.6：35.8。
负极材料的中值粒径为13.8μm，比表面积为3.1m 2/g，碳层的平均厚度为420nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为40％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为3.5％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为133MPa。
实施例10
实施例10与实施例1大致相同，其区别在于，不进行步骤(4)中的二次热处理步骤。
本实施例制得的负极材料包括聚集体，聚集体包括硅粉及碳材料，硅粉及碳材料的质量比为64.1：32.8。
负极材料的中值粒径为14.5μm，比表面积为3.8m 2/g，碳层的平均厚度为380nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为26％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为6.7％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为59MPa。
实施例11
按照与实施例1基本相同的方法制备负极材料，区别在于：步骤(1)中未添加添 加剂(烷基酚聚氧乙烯醚)。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为64.8：35.2。
负极材料的中值粒径为13.8μm，比表面积为3.9m 2/g，碳层的平均厚度为360nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为16％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为9.6％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为95MPa。
实施例12
按照与实施例1基本相同的方法制备负极材料，区别在于：步骤(1)还添加了金属氧化物(SiO)，SiO与硅粉的质量比为5:100。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉、SiO及碳材料的质量比为63.8：4.5：31.7。
负极材料的中值粒径为11.8μm，比表面积为3.5m 2/g，碳层的平均厚度为320nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为18％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.5％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为195MPa。
实施例13
按照与实施例1基本相同的方法制备负极材料，区别在于：步骤(1)还添加了抗拉强度为59Gpa的导电增强剂(单壁碳纳米管)，单壁碳纳米管与硅粉的质量比为1.5:100。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉、单壁碳纳米管及碳材料的质量比为64.8：1.1：34.1。
负极材料的中值粒径为10.4μm，比表面积为2.1m 2/g，碳层的平均厚度为360nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为18.8％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为2.9％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为175MPa。
对比例1
按照与实施例1基本相同的方法制备负极材料，区别在于：步骤(1)未进行研磨分散处理。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为60.8：38.2。
负极材料的中值粒径为10.4μm，比表面积为4.6m 2/g，碳层的平均厚度为320nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为2％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为6.8％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为48MPa。
对比例2
按照与实施例1基本相同的方法制备负极材料，区别在于：步骤(3)未进行融合处理。
本实施例制得的负极材料包括聚集体及包覆于聚集体表面的碳层，聚集体包括纳米硅粉及碳材料，硅粉及碳材料的质量比为76.2：35.2。
负极材料的中值粒径为21.6μm，比表面积为6.9m 2/g，碳层的平均厚度为680nm。
采用上述目标区域比例C的测试方法测试，负极材料中的目标区域比例C为6％。
采用压汞法对负极材料颗粒进行测试，负极材料的孔隙率为13.9％。
采用纳米压痕仪对负极材料颗粒进行测试，负极材料的耐压硬度平均为44MPa。测试方法
(1)扣式电池测试
采用以下方法测试电化学循环性能：将制得的硅碳复合负极材料、导电剂和粘结剂按质量百分比94：1：5将他们溶解在溶剂中混合，控制固含量在50％，涂覆于铜箔集流体上，真空烘干、制得负极极片；然后将传统成熟工艺制备的三元正极极片、1mol/L的LiPF6/碳酸乙烯酯+碳酸二甲酯+甲基乙基碳酸酯(v/v＝1:1:1)电解液、Celgard2400隔膜、外壳采用常规生产工艺装配得到锂离子扣式电池。利用千分尺测量锂离子电池的极片初始厚度为H0，锂离子电池的充放电测试在武汉金诺电子有限公司LAND电池测试***上，在常温条件，0.2C恒流充放电，充放电电压限制在2.75～4.2V，得到首次可逆容量、首圈充电容量和首圈放电容量。首次库伦效率＝首圈放电容量/首圈充电容量。
重复循环50周，利用千分尺测量锂离子电池此时极片的厚度为H1，循环50圈后膨胀率＝(H1-H0)/H0×100％。
重复100周循环，记录放电容量，作为锂离子电池的剩余容量；容量保持率＝剩余容量/初始容量*100％。
(2)聚集体的孔隙率测试：
孔隙率通过压汞法测定。孔隙率至少测定三次，采用至少三次的算术平均作为测定结果。
(3)中值粒径的测试:
本申请中中值粒径的物理意义是颗粒的累计粒度分布百分数达到50％时所对应的粒径，通过马尔文粒度仪测试。马尔文粒度仪利用颗粒对光的散射现象，根据散射光能的分布综合换算出被测颗粒的粒径分布。
(4)耐压硬度的测试：
耐压硬度通过纳米压痕仪测试，采用载荷0.6N，压痕深度0.5μm的方法进行压痕硬度测试。
(5)负极材料的测试密度：
称取空瓶的质量m，注满蒸馏水，称取此时的质量为m1；然后将瓶子清洗，干燥， 在一定量的负极材料加入到比重瓶中，记录此时的总体质量为m2，然后加入蒸馏水，注满比重瓶，称取质量m3，比重瓶的体积v1＝(m1-m)/ρ1，负极材料的体积v2＝(m2-m3)/ρ1,负极材料的测试密度ρ2＝(m3-m)/(V-V1)，ρ1是蒸馏水的密度。
(6)比表面积的测试：
使用麦克比表面积测试仪测试负极材料的比表面积。
(7)抗拉强度测试：
使用拉伸试验机测试导电增强剂的抗拉强度。
上述性能测试的结果如下：
表1.性能比对结果表
Figure PCTCN2022110770-appb-000001
图4为本申请实施例1制备的负极材料的首次充放电曲线，如图4所示，实施例 1制得的负极材料首次充放电容量较高，首次效率也较高，这是因为负极材料中的活性物质保持了适当的间距，有效避免了活性物质的自团聚，可以避免脱嵌锂过程中失去电接触，增强活性物质与碳材料的结合，进而提高负极材料的电化学性能。
图5为本申请实施例1制备的负极材料的循环性能曲线，如图5所示，该负极材料具有优异的循环性能，循环100周容量保持率为93.1％，这是因为聚集体具有较小的孔隙率，电解液也不容易渗透进聚集体内部，该聚集体结构有利于保护内部的活性物质颗粒，可以有效抑制负极材料体积膨胀，降低膨胀率，提升电池循环性能。
如表1所示，实施例1至10制得的负极材料，包括聚集体，其中，聚集体包括活性物质和碳材料，通过控制聚集体中的活性物质的间距，保障活性物质的分散度，可以避免活性物质倾向于团聚，保障聚集体内部的载流子传输通道顺畅。可以避免颗粒的软团聚，活性物质保持适当的间距，也有利于后续碳材料的渗透，提升活性物质与碳材料的结合力，进而提高材料的电化学性能；聚集体具有较小的孔隙率，电解液也不容易渗透进聚集体内部，该聚集体结构有利于保护内部的活性物质颗粒，可以有效抑制负极材料体积膨胀，降低膨胀率，提升电池循环性能。
其中，实施例8的负极材料在制备过程中，一次热处理温度过高，会生成少量不具有活性的SiC材料，使得负极材料的可逆容量和首次库伦效率下降。
实施例9的负极材料在制备过程中，二次热处理温度过低，包覆在聚集体表面的碳源碳化不完全，负极材料的导电性下降，负极材料的首次库伦效率下降。
实施例10的负极材料在制备过程中，聚集体表面未进行碳包覆，没有形成碳层，负极材料的导电性下降，首次库伦效率下降。
实施例11的负极材料在制备过程中，未添加添加剂，活性颗粒与碳材料之间的连接不紧密，因此获得聚集体结构稳定性下降，对膨胀缓冲抑制作用减弱。
实施例12的负极材料在制备过程中，将活性物质、添加剂、第一碳源和溶剂进行分级混合的步骤中还加入了金属氧化物，使得聚集体结构的刚性提升，颗粒循环稳定性提高，循环后极片膨胀率下降。
实施例13的负极材料在制备过程中，将活性物质、添加剂、第一碳源和溶剂进行分级混合的步骤中还加入了导电增强剂，可以有效改善载流子在聚集体内部的传输，增强了聚集体的导电性，负极材料的首次库伦效率提升。并且导电增强剂可以有效提高聚集体的结构稳定性，颗粒循环稳定性提高，循环后极片膨胀率下降。
对比例1的负极材料在制备过程中，步骤(1)中原材料未进行研磨分散，活性物质和碳材料混合均匀度下降，活性物质在原材料中不够分散，导致负极材料的聚集体中，活性物质之间的间距明显下降，活性物质的分散度下降，活性物质倾向于团聚，聚集体内部的载流子传输通道容易堵塞，材料的电化学性能下降。
对比例2的负极材料在制备过程中，步骤(2)前驱体未进行融合处理，整体结构趋向于松散，活性物质与碳材料的连接稳定性差，活性物质与碳材料之间的孔隙增大，导致聚集体的结构强度下降，耐压强度大幅下降，难以抵御活性物质膨胀效应带了的应力变化，膨胀率提高。
本申请虽然以较佳实施例公开如上，但并不是用来限定权利要求，任何本领域技 术人员在不脱离本申请构思的前提下，都可以做出若干可能的变动和修改，因此本申请的保护范围应当以本申请权利要求所界定的范围为准。

Claims (14)

  1. 一种负极材料，其特征在于，包括聚集体，所述聚集体包括活性物质和碳材料，其中，所述负极材料的孔隙率≤10％，且所述负极材料中的目标区域比例C≥15％，
    其中，所述目标区域比例C通过以下的测试方法获得：
    将所述负极材料颗粒的SEM切面分割成面积为A×B的区域，其中A及B均≤1微米，统计单个所述负极材料颗粒的所有所述区域内的所述活性物质的分布情况，将所述活性物质之间的间距为10nm～300nm的区域的数量计为N1，将所述活性物质之间的间距小于10nm的区域和大于300nm的区域的总数量计为N2，单个所述负极材料颗粒的目标区域比例X定义为X＝N1/N2，C为任意5个所述负极材料颗粒的X值的算术平均值。
  2. 根据权利要求1所述的负极材料，其特征在于，所述聚集体还包括金属氧化物。
  3. 根据权利要求1所述的负极材料，其特征在于，所述聚集体还包括导电增强剂。
  4. 根据权利要求2所述的负极材料，其特征在于，包含以下特征(1)至(6)中的至少一种：
    (1)所述金属氧化物分布于所述活性物质之间，所述活性物质和所述金属氧化物之间填充有所述碳材料；
    (2)所述活性物质与所述金属氧化物之间具有孔隙，所述孔隙中填充有所述碳材料；
    (3)所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种；
    (4)所述金属氧化物呈片状和/或长条状；
    (5)所述金属氧化物的长径比大于2；
    (6)所述金属氧化物与所述活性物质的质量比为(1～20)：100。
  5. 根据权利要求3所述的负极材料，其特征在于，包含以下特征(1)至(6)中的至少一种：
    (1)所述导电增强剂包括合金材料及导电碳中的至少一种；
    (2)所述导电碳包括碳纳米管、碳纤维、石墨纤维中的至少一种；
    (3)所述导电增强剂的电导率＞10 2S/m；
    (4)所述导电增强剂呈片状和/或长条状，所述导电增强剂的长径比为2～3000；
    (5)所述导电增强剂与所述活性物质的质量比为(0.1～10)：100；
    (6)所述导电增强剂的抗拉强度≥500MPa。
  6. 根据权利要求1～5任一项所述的负极材料，其特征在于，包含以下特征(1)至(4)中的至少一种：
    (1)所述活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x＜2)、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种；
    (2)所述活性物质的中值粒径为1nm至500nm；
    (3)所述碳材料包括无定形碳、结晶碳及中间相碳微球中的至少一种；
    (4)所述活性物质与所述碳材料的质量比为(20～70)：(10～80)。
  7. 根据权利要求1～6任一项所述的负极材料，其特征在于，包含以下特征(1) 至(8)中的至少一种：
    (1)所述负极材料还包括包覆于所述聚集体的至少部分表面的碳层；
    (2)所述碳层的材料包括无定形碳；
    (3)所述碳层的厚度为10nm至1500nm；
    (4)所述负极材料的中值粒径为0.5μm～30μm；
    (5)所述负极材料的比表面积≤10m 2/g；
    (6)所述负极材料的耐压硬度≥50Mpa；
    (7)所述负极材料的孔隙率≤10％；
    (8)所述聚集体密度满足以下关系：所述聚集体的测试密度与所述聚集体的平均密度的差值≤5％。
  8. 一种负极材料的制备方法，其特征在于，包括以下步骤：
    将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散后除去所述溶剂得到第一前驱体；
    对所述第一前驱体在600℃～1200℃进行一次热处理得到第二前驱体；及
    对所述第二前驱体进行密实化处理，得到聚集体。
  9. 根据权利要求8所述的制备方法，其特征在于，包括以下特征(1)至(22)中的至少一种：
    (1)所述活性物质包括Li、Na、K、Sn、Ge、Si、SiO x(0＜x＜2)、Fe、Mg、Ti、Zn、Al、P及Cu中的至少一种；
    (2)所述第一碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯、沥青中的至少一种；
    (3)所述第一碳源与所述活性物质的质量比为(5～40)：100；
    (4)所述溶剂包括有机溶剂；
    (5)所述有机溶剂包括甲醇、乙醇、乙二醇、丙醇、异丙醇、丙三醇、正丁醇、异丁醇及戊醇中的至少一种；
    (6)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了添加剂；
    (7)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了添加剂，所述添加剂包括表面活性剂、偶联剂中的至少一种；
    (8)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了添加剂，所述添加剂包括表面活性剂，所述表面活性剂包括正十八酸、月桂酸、聚丙烯酸、十二烷基苯磺酸钠、正二十酸、棕榈酸、十四烷酸、十一烷酸、十六烷基三甲基溴化胺及聚乙烯吡咯烷酮中的至少一种；
    (9)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了添加剂，所述添加剂包括偶联剂，所述偶联剂包括硅烷偶联剂，所述硅烷偶联剂包括γ-氨丙基三乙氧基硅烷、γ-缩水甘油醚氧丙基三甲氧基硅烷、γ-甲基丙烯酰氧基丙基三甲氧基硅烷；
    (10)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤 中还加入了添加剂，所述活性物质与所述添加剂的质量比为(15～120)：(1～10)；
    (11)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物；
    (12)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物，所述金属氧化物的化学通式为M xO y，0.2≤y/x≤3，其中，M包括Sn、Ge、Si、Fe、Cu、Ti、Na、Mg、Al、Ca及Zn中的至少一种；
    (13)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物，所述金属氧化物呈片状和/或长条状；
    (14)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物，所述金属氧化物的长径比大于2；
    (15)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了金属氧化物，所述金属氧化物与所述活性物质的质量比为(1～20)：100；
    (16)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂；
    (17)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂，所述导电增强剂与所述活性物质的质量比为(0.1～10)：100；
    (18)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂，所述导电增强剂包括合金材料及导电碳中的至少一种；
    (19)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂，所述导电碳包括碳纳米管、碳纤维、石墨纤维中的至少一种；
    (20)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂，所述导电增强剂的电导率为＞10 2S/m；
    (21)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂，所述导电增强剂呈片状和/或长条状；
    (22)所述将包含活性物质、第一碳源和溶剂的原料进行混合并充分分散的步骤中还加入了导电增强剂，所述导电增强剂的长径比为2～3000。
  10. 根据权利要求8或9所述的制备方法，其特征在于，包括以下特征(1)至(5)中的至少一种：
    (1)所述充分分散的处理方式包括机械搅拌、超声分散、研磨分散中的至少一种；
    (2)所述将包含活性物质、第一碳源和溶剂的原料进行混合采用分级混合的方式；
    (3)所述将包含活性物质、第一碳源和溶剂的原料进行混合具体为：将所述活性物质与所述溶剂混合形成第一预混物，将所述第一碳源与所述溶剂混合形成第二预混物，再将所述第一预混物与所述第二预混物混合；
    (4)所述制备第一前驱体步骤包括将活性物质、第一碳源和溶剂进行混合并充分分散后，进行干燥处理得到所述第一前驱体；
    (5)所述制备第一前驱体步骤包括将活性物质、第一碳源和溶剂进行混合并充分分散后，进行干燥处理得到所述第一前驱体，所述干燥处理的温度为40℃～600℃，时间为1h～15h。
  11. 根据权利要求8～10任一项所述的制备方法，其特征在于，包括以下特征(1) 至(8)中的至少一种：
    (1)所述密实化处理包括融合处理、混捏挤压处理、模压处理、等静压处理、及浸渍处理中的至少一种；
    (2)所述密实化处理包括融合处理，所述融合处理为机械融合；
    (3)所述密实化处理包括融合处理，所述融合处理为机械融合，所述机械融合所用的融合机的转速为300r/min～3000r/min；
    (4)所述密实化处理包括融合处理，所述融合处理为机械融合，所述机械融合所用的融合机刀具间隙宽度为0.01cm～0.9cm；
    (5)所述密实化处理包括融合处理，所述融合处理为机械融合，所述机械融合时间至少为0.5h；
    (6)所述一次热处理的时间为1h～10h；
    (7)所述一次热处理过程通有保护性气体；
    (8)所述一次热处理过程通有保护性气体，所述保护性气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
  12. 根据权利要求8～11任一项所述的制备方法，其特征在于，包括以下特征(1)至(3)中的至少一种：
    (1)所述方法还包括对所述聚集体进行碳包覆处理；
    (2)所述方法还包括对所述聚集体进行碳包覆处理，所述碳包覆处理的步骤包括：将第二前驱体与第二碳源进行混合、二次热处理；
    (3)所述方法还包括对所述聚集体进行碳包覆处理，所述碳包覆处理的步骤包括：将所述聚集体与第二碳源混合、二次热处理。
  13. 根据权利要求12任一项所述的制备方法，其特征在于，包括以下特征(1)至(6)中的至少一种：
    (1)所述第二前驱体与所述第二碳源的质量比为(30～100)：(10～70)；
    (2)所述第二碳源包括蔗糖、葡萄糖、聚乙烯、聚乙烯醇、聚乙二醇、聚苯胺、环氧树脂、酚醛树脂、糠醛树脂、丙烯酸树脂、聚环氧乙烷、聚偏氟乙烯、聚丙烯腈、聚氯乙烯及沥青中的至少一种；
    (3)所述聚集体与所述第二碳源的质量比为(20～100)：(10～120)；
    (4)所述二次热处理的温度为600℃～1200℃，所述二次热处理的时间为1h～10h；
    (5)所述二次热处理过程通有保护性气体；
    (6)所述二次热处理过程通有保护性气体，所述保护性气体包括氮气、氦气、氖气、氩气及氪气中的至少一种。
  14. 一种锂离子电池，所述锂离子电池包括根据权利要求1至7任一项所述的负极材料或根据权利要求8至13任一项所述制备方法制得的负极材料。
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Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101118964A (zh) * 2007-08-31 2008-02-06 深圳市贝特瑞新能源材料股份有限公司 提高锂离子电池电极材料性能的方法
CN109273713A (zh) * 2018-08-22 2019-01-25 广东东岛新能源股份有限公司 一种动力电池负极用整形焦粒及其制备方法
CN109786706A (zh) * 2019-01-17 2019-05-21 新奥石墨烯技术有限公司 负极材料及其制备方法、负极以及电池
CN110718685A (zh) * 2019-10-22 2020-01-21 安普瑞斯（南京）有限公司 一种用于电极材料的硅氧颗粒及其制备方法和应用
CN110885083A (zh) * 2018-09-07 2020-03-17 三星Sdi株式会社 负极活性物质及其制备方法、负电极和可再充电锂电池
CN111204756A (zh) * 2020-02-27 2020-05-29 深圳市翔丰华科技股份有限公司 一种快充石墨负极材料及其制备方法
CN113422029A (zh) * 2021-06-29 2021-09-21 贝特瑞新材料集团股份有限公司 负极材料及其制备方法、锂离子电池

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101118964A (zh) * 2007-08-31 2008-02-06 深圳市贝特瑞新能源材料股份有限公司 提高锂离子电池电极材料性能的方法
CN109273713A (zh) * 2018-08-22 2019-01-25 广东东岛新能源股份有限公司 一种动力电池负极用整形焦粒及其制备方法
CN110885083A (zh) * 2018-09-07 2020-03-17 三星Sdi株式会社 负极活性物质及其制备方法、负电极和可再充电锂电池
CN109786706A (zh) * 2019-01-17 2019-05-21 新奥石墨烯技术有限公司 负极材料及其制备方法、负极以及电池
CN110718685A (zh) * 2019-10-22 2020-01-21 安普瑞斯（南京）有限公司 一种用于电极材料的硅氧颗粒及其制备方法和应用
CN111204756A (zh) * 2020-02-27 2020-05-29 深圳市翔丰华科技股份有限公司 一种快充石墨负极材料及其制备方法
CN113422029A (zh) * 2021-06-29 2021-09-21 贝特瑞新材料集团股份有限公司 负极材料及其制备方法、锂离子电池

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