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CN-122025570-A - Preparation method of high-magnification natural graphite secondary particle anode material

CN122025570ACN 122025570 ACN122025570 ACN 122025570ACN-122025570-A

Abstract

The invention relates to a preparation method of a high-magnification natural graphite secondary particle anode material. Mixing natural graphite with asphalt, heating to coat asphalt on the surface of the natural graphite for physical modification to obtain modified natural graphite A, mixing the modified natural graphite with asphalt for granulation to obtain a natural graphite granulated product B, carrying out high-temperature heat treatment to obtain a natural graphite material C, mixing the natural graphite material C with a coating agent, and carrying out high-temperature carbonization to obtain the natural graphite negative electrode material. According to the invention, the specific surface area and processing difficulty of the natural graphite are reduced by means of single pre-coating modification, granulation and liquid phase post-coating, so that the natural graphite has a stable structure and a three-dimensional network structure, and the isotropy is obviously improved, so that the natural graphite serving as a negative electrode material has excellent cycle performance and multiplying power performance.

Inventors

  • WANG XIAOBO
  • LI ZHENQING
  • SUN TAO
  • ZHANG JIANQI
  • YAN YU

Assignees

  • 湖北宝乾新能源材料有限公司

Dates

Publication Date
20260512
Application Date
20251223

Claims (10)

  1. 1. The preparation method of the high-magnification natural graphite secondary particle anode material is characterized by comprising the following steps of: (1) Mixing natural graphite with concentrated particle size distribution and proper particle size with proper amount of asphalt in a roller furnace, and then heating and scattering to coat asphalt on the surface of the natural graphite to obtain asphalt modified natural graphite particles A; (2) Mixing asphalt modified natural graphite particles A with a proper amount of asphalt in a reaction kettle, and heating, granulating and scattering to obtain natural graphite granules B with proper granularity; (3) Carrying out heat treatment on the natural graphite granules B at 1800-2200 ℃ to obtain a natural graphite material C; (4) And uniformly stirring the natural graphite material C and the liquid phase coating agent S, and obtaining the natural graphite secondary particle anode material after fusion high-temperature carbonization.
  2. 2. The preparation method of the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the preparation process of the liquid phase coating agent in the step (4) comprises the following steps of mixing asphalt with wash oil according to the mass ratio of 1 (2.5-4), wherein the softening point temperature of the asphalt is 160-230 ℃, and stirring the mixture in a heating kettle at 40-80 ℃ for 60-180min to obtain the liquid phase coating agent S.
  3. 3. The preparation method of the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the particle size and the particle size distribution of the natural graphite in the step (1) are D10 more than or equal to 5 mu m, D50 is 8.5+/-2 mu m, and D90 is less than or equal to 16 mu m.
  4. 4. The method for preparing the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the softening point of asphalt in the step (1) is 150-200 ℃, and the asphalt is 20-25% by mass.
  5. 5. The preparation method of the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the granulating temperature in the step (1) is 400-550 ℃, the heating time is 4-8 hours, the granularity D50 of the granulated and modified material is more than or equal to 13.0 mu m, and the granularity D50 of the scattered material is 13.0+/-2.0 mu m.
  6. 6. The preparation method of the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the softening point of asphalt in the step (2) is 200-250 ℃, and the asphalt is used in an amount of 6.0-8.0% by mass.
  7. 7. The preparation method of the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the granulating temperature in the step (2) is 620-680 ℃, the heating time is 4-8h, the granularity D50 of the granulated material is more than or equal to 20.0 mu m, and the granularity of the scattered material is 20+/-1 mu m.
  8. 8. The method for preparing the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the mass ratio of the natural graphite material C to the liquid-phase coating agent S in the step (4) is 8:1-12:1.
  9. 9. The preparation method of the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the highest carbonization temperature in the step (4) is 1150-1300 ℃, the highest temperature treatment time is 4-8h, and the high-temperature carbonized inert gas is any one or mixture of nitrogen, argon, helium and neon.
  10. 10. The method for preparing the high-magnification natural graphite secondary particle anode material according to claim 1, wherein the step (2) is performed by stirring with a spiral stirrer.

Description

Preparation method of high-magnification natural graphite secondary particle anode material Technical Field The invention relates to the technical field of battery electrode materials, in particular to a preparation method of a high-magnification natural graphite secondary particle anode material. Background The lithium ion battery cathode material is an important component in the lithium ion battery, and directly affects the performance and cost of the battery. At present, common lithium ion anode materials in the market comprise natural graphite and artificial graphite, and compared with the artificial graphite, the natural graphite has lower cost and higher theoretical specific capacity, but has slightly poorer performance than the artificial graphite. The natural graphite has perfect crystal structure, is an ideal intercalation lithium ion battery cathode material, has rich earth reserves, simple processing technology and low energy consumption, meets the low-carbon environment-friendly requirement better, and has wide market development prospect. However, due to the anisotropy of natural graphite crystals, lithium ions have directionality in the process of removing/inserting the negative electrode material, the spacing between graphite sheets is smaller, the diffusion efficiency of lithium ions is low, lithium dendrites are easy to form on the surface of a graphite carbon layer during high-current charge and discharge to cause the safety problem of the battery, and the surface property of natural graphite is easy to cause side reactions when the natural graphite contacts with electrolyte, so that the defects of the battery such as the circulation stability, the service life and the like are further influenced. Disclosure of Invention The invention aims to overcome the key technical bottleneck of natural graphite in the application of battery anode materials and promote the large-scale application of the natural graphite in the field of lithium ion battery anode materials. The technical scheme adopted for solving the technical problems is that the preparation method of the high-magnification natural graphite secondary particle anode material comprises the following steps: (1) Mixing natural graphite with concentrated particle size distribution and proper particle size with proper amount of asphalt in a roller furnace with the rotating speed of 0.5-3r/min, and then heating and scattering to coat asphalt on the surface of single natural graphite to obtain asphalt modified natural graphite particles A; (2) Mixing asphalt modified natural graphite particles A with a proper amount of asphalt in a reaction kettle with the rotating speed of 10-500rpm, and heating, granulating and scattering to obtain natural graphite granules B with proper granularity; (3) Carrying out heat treatment on the natural graphite granules B at 1800-2200 ℃ to obtain a natural graphite material C; (4) And uniformly stirring the natural graphite material C and the liquid phase coating agent S, and obtaining the natural graphite secondary particle anode material after fusion high-temperature carbonization. Preferably, the preparation process of the liquid-phase coating agent in the step (4) comprises the following steps of mixing asphalt with wash oil according to the mass ratio of 1 (2.5-4), wherein the softening point temperature of the asphalt is 160-230 ℃, and stirring for 60-180min in a heating kettle at 40-80 ℃ to obtain the liquid-phase coating agent S. Preferably, the particle size and particle size distribution of the natural graphite in the step (1) are D10 more than or equal to 5 mu m, D50 is 8.5+/-2 mu m, and D90 is less than or equal to 16 mu m. Preferably, the softening point of the asphalt in the step (1) is 150-200 ℃, and the amount of the asphalt is 20-25% by mass. Preferably, the granulating temperature in the step (1) is 400-550 ℃, the heating time is 4-8 hours, the granularity D50 of the material after granulating and modifying is more than or equal to 13.0 mu m, and the granularity D50 of the material after scattering is 13.0+/-2.0 mu m. Preferably, the softening point of the asphalt in the step (2) is 200-250 ℃, and the asphalt is used in an amount of 6.0-8.0% by mass. Preferably, the granulating temperature in the step (2) is 620-680 ℃, the heating time is 4-8h, the granularity D50 of the granulated material is more than or equal to 20.0 mu m, and the granularity of the scattered material is 20+/-1 mu m. Preferably, in the step (4), the mass ratio of the natural graphite material C to the liquid-phase coating agent S is 8:1-12:1. Preferably, the carbonization in the step (4) is at the maximum of 1150-1300 ℃, and the highest temperature treatment time is 4-8h. Preferably, the high-temperature carbonization inert atmosphere in the step (4) is any one or a mixture of a plurality of nitrogen, argon, helium and neon. Preferably, in the step (2), the stirring is performed by using a spiral stirrer, and the stirring is i