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CN-121990556-A - Preparation method of carbon-coated hard carbon material used as negative electrode material of sodium ion battery

CN121990556ACN 121990556 ACN121990556 ACN 121990556ACN-121990556-A

Abstract

The invention provides a preparation method of a carbon-coated hard carbon material used as a negative electrode material of a sodium ion battery. The preparation method comprises the following steps of S1, pre-carbonizing a biomass base material for 1-5 hours at 300-600 ℃, crushing the obtained biomass carbon material to obtain a biomass carbon material, S2, uniformly mixing the biomass carbon material obtained in S1 with asphalt according to a mass ratio of 1 (0.01-0.15) to obtain a hard carbon precursor, S3, carbonizing and preserving the hard carbon precursor obtained in S2 for 1-5 hours at 1000-1400 ℃ under inert gas, then cooling to 30-200 ℃, and screening to obtain the carbon-coated hard carbon material. According to the invention, the surface of the biomass carbon material prepared by the biomass base material is coated with a layer of asphalt in situ, and the carbon coated hard carbon material prepared by taking the asphalt as a precursor through a high-temperature carbonization one-step method can effectively improve the specific surface area and the micropore ratio of the material, so that higher reversible capacity and first-circle coulomb efficiency can be obtained in a low-cost high-production-efficiency mode.

Inventors

  • Bao Jingze
  • WANG XIAOWEI
  • LU ZHENBAO

Assignees

  • 内蒙古翔福新能源有限责任公司
  • 包头旭阳硅碳科技有限公司

Dates

Publication Date
20260508
Application Date
20260116

Claims (10)

  1. 1. A preparation method of a carbon-coated hard carbon material comprises the following steps: s1, pre-carbonizing a biomass base material for 1-5 hours at 300-600 ℃, and crushing the obtained product to obtain a biomass charcoal material; S2, uniformly mixing the biomass carbon material obtained in the step S1 with asphalt according to the mass ratio of 1 (0.01-0.15) to obtain a hard carbon precursor; S3, carbonizing and preserving the hard carbon precursor obtained in the S2 for 1-5 hours under the condition of inert gas and 1000-1400 ℃, then cooling to 30-200 ℃, and screening to obtain the carbon-coated hard carbon material.
  2. 2. The preparation method according to claim 1, wherein the preparation method further comprises a step of drying the biomass charcoal material prior to step S1, preferably such that the moisture content of the biomass substrate is reduced to below 12%.
  3. 3. The production method according to claim 1 or 2, wherein, in the step S1, The biomass base material is one or more selected from coconut husk, bamboo fragments and straw, and/or The pre-carbonization operation has a heating rate of 5-10deg.C/min, and/or The pre-carbonization is carried out at a temperature of 500-600 ℃ and/or The pulverizing operation controls the particle size D 50 to be in the range of 6 to 8 μm.
  4. 4. The production process according to any one of claims 1 to 3, wherein in the step S2, The bitumen is petroleum or coal-based bitumen having a softening point in the range of 100-280 ℃, in particular 180-220 ℃, more in particular 200-240 ℃, a particle size D 50 of 2-10 μm, and/or The mass ratio of the biomass charcoal material to the asphalt is 1 (0.06-0.08).
  5. 5. The production method according to any one of claims 1 to 4, wherein in the step S3, The inert gas comprises nitrogen (N 2 ), argon (Ar), N 2 /Ar mixture, and/or The carbonization operation has a heating rate of 3-7deg.C/min, and/or The carbonization heat preservation is carried out under the condition of 1200-1300 ℃, and/or The carbonization heat preservation is carried out for 1.5 to 3 hours, and/or Said cooling to 100-200deg.C, and/or The screening operation adopts a 300-500 mesh screen.
  6. 6. A carbon coated hard carbon material prepared by the method of any one of claims 1 to 5.
  7. 7. The use of the carbon-coated hard carbon material according to claim 6 for preparing a negative electrode material of a sodium ion battery.
  8. 8. Use of the carbon-coated hard carbon material according to claim 6 for the preparation of sodium ion batteries.
  9. 9. A sodium ion battery anode material comprising the carbon-coated hard carbon material of claim 6.
  10. 10. A sodium ion battery comprising the sodium ion battery anode material of claim 9.

Description

Preparation method of carbon-coated hard carbon material used as negative electrode material of sodium ion battery Technical Field The invention belongs to the technical field of sodium ion battery anode materials, and particularly relates to a preparation method of a carbon-coated hard carbon material used as a sodium ion battery anode material. Background The sodium ion battery is an important supplement of a lithium ion battery system by virtue of the characteristics of high abundance of resources, low cost, good comprehensive electrochemical performance and the like, and the sodium ion battery and the lithium ion battery have similarity in core working mechanism and battery constitution. In a sodium ion battery negative electrode material system, a hard carbon material is recognized as a sodium ion battery negative electrode material with the most practical prospect due to the advantages of wide raw material sources, relatively simple preparation process, relatively high reversible sodium storage capacity, proper average working potential, outstanding cycle stability and the like. The sodium storage behavior of hard carbon materials involves multiple mechanisms in which sodium ions can be stored in the surface adsorption sites, lamellar structure interstices, and internal micropores of the hard carbon material. It is worth noting that while surface defects can contribute to a part of capacity, excessive defects can exacerbate interfacial side reactions and cause significant irreversible loss of sodium ions, and meanwhile, internal micropores (particularly wedge-shaped holes of about 1 nm) are key spaces for efficient sodium storage, and pore size distribution needs to be accurately regulated, and excessive or insufficient pore size distribution can cause significant reduction of specific capacity of materials. Therefore, by accurately regulating and controlling the surface defect density and the internal micropore structure (particularly optimizing the pore size distribution) of the hard carbon, the first-week coulomb efficiency of the hard carbon can be effectively improved, the reversible sodium storage space can be expanded, and the capacity and first-effect collaborative optimization can be further realized. Disclosure of Invention In view of this, the present invention aims to address at least one of the drawbacks of the prior art. Therefore, the invention aims to provide a preparation method of a carbon-coated hard carbon material used as a negative electrode material of a sodium ion battery, which can effectively solve the problems that the specific surface area of the hard carbon material meeting the electrochemical performance requirement is difficult to improve and the process cost is high and complex, and the obtained negative electrode product can meet the application requirement of a lithium ion battery in terms of specific surface area, specific capacity and first coulombic efficiency. Accordingly, in one aspect, the present invention provides a method for preparing a carbon-coated hard carbon material, comprising the steps of: s1, pre-carbonizing a biomass base material for 1-5 hours (particularly, 3 hours) at 300-600 ℃, preferably 500-600 ℃, and crushing the obtained biomass base material to obtain a biomass charcoal material; S2, uniformly mixing the biomass carbon material obtained in the step S1 with asphalt according to the mass ratio of 1 (0.01-0.15) to obtain a hard carbon precursor; S3, carbonizing and preserving the hard carbon precursor obtained in S2 for 1-5 hours (such as 1-4 or 1.5-3 hours, especially 1.5, 2, 2.5 or 3 hours) under the condition of inert gas and 1000-1400 ℃ (such as 1050-1350, 1100-1350, 1150-1300 ℃ and the like, especially 1200-1300 ℃), then cooling to 30-200 ℃ (such as 50-200 or 100-200 ℃, especially 150 ℃), and screening to obtain the carbon-coated hard carbon material. In some embodiments, in the step S1, the biomass substrate may be one or more selected from coconut shells, bamboo fragments, and straw. The biomass substrate may have a moisture content of 10-25%. In some embodiments, in the step S1, the temperature rising rate of the pre-carbonization operation may be 5 to 10 ℃. In some embodiments, in step S1, the comminution operation controls the particle size D 50 to be in the range of 6-8 μm. In some embodiments, the preparation method further includes a step of performing a drying operation on the biomass charcoal material before step S1. The torrefaction operation reduces the moisture content of the biomass substrate to below 12%. In some embodiments, in step S2, the pitch is petroleum pitch or coal-based pitch having a softening point in the range of 100-280 ℃ (particularly 180-220 ℃, more particularly 200-240 ℃, e.g., 210, 220, 230 ℃, etc.), and a particle size D 50 of 2-10 μm. In some embodiments, in step S2, the mass ratio of biomass charcoal material to pitch is 1 (0.06-0.08), such as 1:0.06, 1:0.07, 1:0.08. In some embodiments, in the step S3,