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CN-122000311-A - Graphite material, preparation method thereof, electrochemical device and electronic equipment

CN122000311ACN 122000311 ACN122000311 ACN 122000311ACN-122000311-A

Abstract

The invention discloses a graphite material, a preparation method thereof, an electrochemical device and electronic equipment. The particles of the graphite material comprise a core and a carbon coating layer, wherein the core comprises a graphite matrix and silicon, the silicon is positioned in the graphite matrix, the graphite material comprises a silicon-rich region, the center of a cross section along the longest diameter of the particles of the graphite material is taken as a circle center, the region extending outwards along the longest diameter direction from the circle center from 75% radius to 95% radius of the particles of the graphite material is a silicon-rich region, the mass ratio of silicon element in the silicon-rich region to the total mass of the graphite material is C1, C1 is 2-4%, and the mass ratio of silicon element in the silicon-rich region to the total mass of silicon element in the graphite material is C2:C2≥90%. The graphite material provided by the invention has high capacity and good structural stability, and has good cycle performance when being used as a battery anode material.

Inventors

  • HOU SHUYAN

Assignees

  • 远景动力技术(江苏)有限公司
  • 远景睿泰动力技术(上海)有限公司

Dates

Publication Date
20260508
Application Date
20241107

Claims (10)

  1. 1. A graphite material, wherein particles of the graphite material comprise a core and a carbon cladding, the core comprising a graphite matrix and silicon, the silicon being located within the graphite matrix; Wherein the graphite material comprises a silicon-rich region; Taking the center of a cross section along the longest diameter of the particles of the graphite material as a circle center, and extending outwards along the longest diameter direction from the circle center, wherein a region from 75% radius to 95% radius of the particles of the graphite material is a silicon-rich region; The mass ratio of silicon element in the silicon-rich region to the total mass of the graphite material is C1, and C1 is 2% -4%; the mass ratio of silicon element in the silicon-rich region to the total mass of silicon element in the graphite material is C2:C2 is more than or equal to 90 percent.
  2. 2. The graphite material of claim 1, wherein the graphite material satisfies one or both of the following conditions (a) - (d): (a) F is more than or equal to 25mN and less than or equal to 35mN, F is more than or equal to 35mN, is a crushing force; (b) 10% < Q less than or equal to 15%, Q is an irreversible deformation amount; (c) C1 is 2.5% -3.5%; (d) C2 is 93% -97%.
  3. 3. The graphite material of claim 1, wherein the graphite material satisfies one or more of the following conditions (a) - (c): (a) The particle size of the graphite material is 6-13 mu m; (b) The thickness of the carbon coating layer is 10 mu m-100 mu m; (c) In the graphite material, the density of holes is 1000-20000 holes/cm 2 .
  4. 4. A method of preparing a graphite material according to any one of claims 1 to 3, comprising the steps of: (1) Pore-forming is carried out on the graphite raw material to obtain a graphite matrix; (2) Carrying out vapor deposition on the graphite matrix by using a silicon source to obtain a graphite material precursor; (3) And (3) coating carbon on the graphite material precursor to obtain the graphite material.
  5. 5. The method of preparing a graphite material as set forth in claim 4, wherein the method of preparing a graphite material satisfies one or more of the following conditions (a) - (d): (a) The mass ratio of the pore-forming agent adopted by the pore-forming to the graphite raw material is (0.005-0.04): 1; (b) The pore-forming agent adopted in the pore-forming is ZnCL 2 and/or aluminum hydroxide; (c) The pore-forming step comprises the steps of carrying out heat treatment on the mixture of the graphite raw material and the pore-forming agent, wherein the temperature of the heat treatment is 500-600 ℃; (d) After the pore formation is completed, washing is also carried out by using alkali solution.
  6. 6. The method of producing a graphite material as claimed in claim 4, wherein the graphite raw material is a microcrystalline graphite raw material which satisfies one or both of the following conditions (a) to (b): (a) La is less than or equal to 72 nm, lc is less than or equal to 15 nm, wherein La is the lattice constant of graphite crystals in the microcrystalline graphite raw material at 110 faces, and Lc is the lattice constant of graphite crystals in the microcrystalline graphite raw material at 002 faces; F1 More than or equal to 15 mN, F1 is the crushing force of the particles; (b) The microcrystalline graphite raw material is prepared by the following method: S1, performing first mixing on a microcrystalline graphite precursor and a binder, and adding a solvent for second mixing to obtain a mixture, wherein the temperature of the first mixing is 5-20 ℃ below the softening point of the binder; S2, pressing the mixture to obtain a microcrystalline graphite rough blank; s3, paving the microcrystalline graphite rough blank on the surface layer of a graphitization furnace, paving a graphitization heat preservation material on the microcrystalline graphite rough blank, and performing graphitization treatment, wherein the microcrystalline graphite rough blank is graphitized to obtain a graphitized microcrystalline graphite rough blank; S4, crushing the graphitized microcrystalline graphite rough blank to obtain a microcrystalline graphite raw material.
  7. 7. The method of preparing a graphite material as recited in claim 4, wherein step (2) satisfies one or more of the following conditions (a) - (d): (a) The temperature of the vapor deposition is 450-750 ℃; (b) The time of the vapor deposition is 6h-10h and, (C) The silicon source is silicon trichloride; (d) The mass ratio of the vapor deposited silicon element to the graphite matrix is 1 (10-20).
  8. 8. The method of preparing a graphite material as recited in claim 4, wherein step (3) satisfies one or more of the following conditions (a) - (c): (a) The carbon source coated by carbon is one or more of petroleum asphalt, phenolic resin, coal tar and coumarone resin; (b) The temperature of the carbon coating is 850-1200 ℃; (c) The carbon coating time is 6-10 h.
  9. 9. An electrochemical device comprising a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode material layer and a negative electrode current collector, the negative electrode material layer comprising the graphite material of any one of claims 1-3.
  10. 10. An electronic device characterized in that it comprises the electrochemical device as claimed in claim 9.

Description

Graphite material, preparation method thereof, electrochemical device and electronic equipment Technical Field The invention relates to a graphite material, a preparation method thereof, an electrochemical device and electronic equipment. Background The graphite material is a common negative electrode material in the field of batteries, and the microcrystalline graphite has low cost and particularly has obvious advantages compared with the conventional crystalline flake graphite in dynamics, but the capacity and the compaction density of the microcrystalline graphite are generally lower than those of the conventional crystalline flake graphite, so that the microcrystalline graphite is limited to be used as the negative electrode material in the field of lithium ion batteries. In the prior art, for example, CN 110416497A adopts a method of mixing a silicon carbon material and microcrystalline graphite by isostatic pressing to improve the capacity, but the method essentially carries out physical compounding on the two materials, the expansion of the silicon material cannot be effectively inhibited, the cycle performance and the high-temperature performance of the material are still short plates, and CN 109592677A adopts an intercalation treatment method to enlarge the lattice spacing to increase the lithium intercalation capability of the microcrystalline graphite, but the treatment can obviously deteriorate the first effect and the structural stability of the material. Therefore, development of microcrystalline graphite having high capacity and good structural stability and cycle performance is of great significance. Disclosure of Invention The invention mainly aims to overcome the defects of low capacity and low compaction density of microcrystalline graphite in the prior art, and poor structural stability and poor cycle performance when the microcrystalline graphite is used as a battery cathode material, and provides a graphite material, a preparation method thereof, an electrochemical device and electronic equipment. The graphite material provided by the invention has high capacity and good structural stability, and has good cycle performance when being used as a battery anode material. The invention provides the following technical scheme for overcoming the technical problems. In a first aspect, the present invention provides a graphite material, the particles of which comprise a core and a carbon coating, the core comprising a graphite matrix and silicon, the silicon being located within the graphite matrix; Wherein the graphite material comprises a silicon-rich region; Taking the center of a cross section along the longest diameter of the particles of the graphite material as a circle center, and extending outwards along the longest diameter direction from the circle center, wherein a region from 75% radius to 95% radius of the particles of the graphite material is a silicon-rich region; The mass ratio of silicon element in the silicon-rich region to the total mass of the graphite material is C1, and C1 is 2% -4%; the mass ratio of silicon element in the silicon-rich region to the total mass of silicon element in the graphite material is C2:C2 is more than or equal to 90 percent. In a second aspect, the present invention provides a method of preparing a graphite material as described above, comprising the steps of: (1) Pore-forming is carried out on the graphite raw material to obtain a graphite matrix; (2) Carrying out vapor deposition on the graphite matrix by using a silicon source to obtain a graphite material precursor; (3) And (3) coating carbon on the graphite material precursor to obtain the graphite material. In a third aspect, the present invention provides an electrochemical device comprising a negative electrode sheet comprising a negative electrode material layer and a negative electrode current collector, the negative electrode material layer comprising a graphite material as described above. In a fourth aspect, the present invention provides an electronic device comprising an electrochemical apparatus as described above. On the basis of conforming to the common knowledge in the field, the above preferred conditions can be arbitrarily combined to obtain the preferred examples of the invention. The reagents and materials used in the present invention are commercially available. The invention has the positive progress effects that: According to the invention, the silicon-rich region with specific silicon distribution is arranged in the graphite matrix, and the carbon coating layer is combined, so that the provided graphite material can inhibit the expansion or the falling of silicon while having larger silicon content, has good structural stability and high capacity, greatly improves the cycle performance when being used as a battery anode material, and further has good high-temperature storage performance and quick charge performance. Detailed Description Graphite material The graphite mat