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CN-121990567-A - Graphite material, preparation method thereof, electrochemical device and electronic equipment

CN121990567ACN 121990567 ACN121990567 ACN 121990567ACN-121990567-A

Abstract

The invention discloses a graphite material, a preparation method thereof, an electrochemical device and electronic equipment. The graphite material meets the following conditions that 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 graphite material on the 110 plane, lc is the lattice constant of graphite crystals in the graphite material on the 002 plane, F is more than or equal to 15 mN, and F is the crushing force of particles. The electrochemical device (especially lithium ion battery) containing the same can ensure excellent initial effect and quick charge performance and has excellent self-discharge performance, capacity performance and cycle performance.

Inventors

  • HOU SHUYAN

Assignees

  • 株式会社AESC日本

Dates

Publication Date
20260508
Application Date
20241107

Claims (10)

  1. 1. A graphite material, characterized in that it meets the following conditions: 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 graphite material on the 110 plane, and Lc is the lattice constant of graphite crystals in the graphite material on the 002 plane; b. f is greater than or equal to 15 mN, F is particle crushing force.
  2. 2. The graphite material according to claim 1, characterized in that it fulfils one or more of the following conditions a-d: a、La≤60 nm; b、Lc≤12 nm; c、15 mN≤F≤25 mN; d. 0<S is less than or equal to 0.1, S is the granularity distribution symmetry.
  3. 3. The graphite material according to claim 1, characterized in that it fulfils one or more of the following conditions a-d: a. the Dv50 particle size of the graphite material is 10-13 mu m; b. The sphericity of the graphite material is 0.5-1.0; c. the carbon content of the graphite material is more than 99.9%, and the percentage is the mass percentage of the graphite material; d. The graphite material is microcrystalline graphite.
  4. 4. A method of preparing a graphite material according to any one of claims 1 to 3, comprising the steps of: S1, carrying out first mixing on a 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 graphite rough blank; s3, paving the graphite rough blank on the surface layer of a graphitizing device, paving a graphitizing heat preservation material on the graphite rough blank, and performing graphitizing treatment, wherein the graphite rough blank is subjected to graphitizing treatment to obtain a graphitized graphite rough blank; And S4, crushing the graphitized graphite rough blank to obtain the graphite material.
  5. 5. The method of claim 4, wherein in step S1, the first mixing temperature is 8-15 ℃ below the softening point of the binder.
  6. 6. The method of preparing a graphite material as claimed in claim 4, wherein step S1 satisfies one or more of the following conditions a-i: a. In the step S1, the sphericity of the graphite precursor is 0.7-1.0; b. in the step S1, the graphite precursor is natural microcrystalline graphite; c. In the step S1, the fixed carbon content of the graphite precursor is 88-91%, and the percentage is the mass percentage of the graphite precursor; d. in the step S1, the Dv50 particle size of the graphite precursor is 6-8 mu m; e. In the step S1, the mass ratio of the graphite precursor to the binder is (4-7): 1; f. in step S1, the binder includes one or more of petroleum asphalt, phenolic resin, epoxy resin, and coal tar; g. in the step S1, the softening point of the binder is 100-250 ℃; h. in step S1, the solvent is selected from one or more of xylene, toluene and n-hexane; i. in step S1, the solid content of the mixture is 40% -60%, and the percentage is the mass of the solid component of the mixture and the mass percentage of the solid component of the mixture.
  7. 7. The method of preparing a graphite material as claimed in claim 4, wherein step S1 and step S2 satisfy one or more of the following conditions a-d: a. In step S1, the first mixing mode is stirring; b. in step S1, the second mixing mode is stirring; c. In the step S1, the preparation method of the graphite precursor comprises the following steps of performing water washing flotation on graphite ore, and then performing coarse crushing and sphericizing treatment to obtain the graphite precursor; d. In step S2, the pressing is isostatic pressing.
  8. 8. The method of preparing a graphite material as claimed in claim 4, wherein steps S3 and S4 satisfy one or more of the following conditions a to f: a. In step S3, the temperature of the graphitization treatment is more than 1600 ℃; b. in the step S3, the graphitization treatment time is 18-40h; c. in the step S3, the graphitized heat preservation material is petroleum coke and/or asphalt coke; d. in step S3, the graphitizing device is a graphitizing furnace; e. in the step S4, sieving and magnetic impurity removal are further included after the crushing treatment; f. in the step S4, the crushing treatment is to crush the particles to have a Dv50 particle diameter of 10-13 μm.
  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 Microcrystalline graphite is a natural graphite with a structure having a small unit cell and rich pores, so that the kinetic advantage of the microcrystalline graphite is greater than that of conventional crystalline flake natural graphite, and the capacity and the compaction are higher than those of conventional artificial graphite. In addition, the microcrystalline graphite raw material is very low, which is about 20-30% of the natural crystalline flake graphite with the same quality, so that the microcrystalline graphite has good application prospect. However, the content of impurities in the natural mined microcrystalline graphite is extremely high, when the natural mined microcrystalline graphite is used as a negative electrode material of a lithium ion battery, impurities are required to be removed firstly, the impurity removal process is complex, the impurity removal cost is about 2-3 times that of the natural crystalline graphite with the same quality, and the application of the microcrystalline graphite is greatly limited by comprehensively considering that the cost is not dominant. The existing impurity removal technology is like that of the Chinese patent application CN107555426A, the microcrystalline graphite is subjected to impurity removal through an acid-base and high-temperature heat treatment mode, low energy consumption is declared, but the waste acid and the waste base are treated, the crucible furnace is required to be occupied, the cost is greatly increased, the structure of a graphite material can be damaged, and the lithium ion battery containing the microcrystalline graphite material cannot guarantee excellent initial effect and quick charge performance. The Chinese patent application CN109616640A is coated in nitrogen atmosphere by adding inorganic salt, so that the cycle performance of microcrystalline graphite is improved, however, the experimental process is not suitable for large-scale industrialized production, and the price of the used experimental product is high, so that the cost reduction of the final product is not facilitated. Although the cycle performance of the lithium ion battery using the microcrystalline graphite is improved, excellent initial efficiency and quick charge performance cannot be ensured. Therefore, how to realize a lithium ion battery containing a graphite material is important to ensure excellent initial efficiency and quick charge performance. Disclosure of Invention The invention provides a graphite material, a preparation method thereof, an electrochemical device and electronic equipment, and aims to solve the problem that the existing lithium ion battery containing the graphite material cannot ensure excellent initial effect and quick charge performance. The graphite material has extremely small La and Lc and larger particle crushing force F, and an electrochemical device (especially a lithium ion battery) containing the graphite material can ensure excellent initial effect and quick charge performance and also has excellent self-discharge performance, capacity performance and cycle performance. In order to achieve the above object, the present invention adopts the following technical scheme. In a first aspect, the present invention provides a graphite material which satisfies the following conditions: 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 graphite material on the 110 plane, and Lc is the lattice constant of graphite crystals in the graphite material on the 002 plane; b. f is greater than or equal to 15 mN, F is particle crushing force. In a second aspect, the present invention provides a method for preparing a graphite material as described above, comprising the steps of: S1, carrying out first mixing on a 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 graphite rough blank; s3, paving the graphite rough blank on the surface layer of a graphitizing device, paving a graphitizing heat preservation material on the graphite rough blank, and performing graphitizing treatment, wherein the graphite rough blank is subjected to graphitizing treatment to obtain a graphitized graphite rough blank; And S4, crushing the graphitized graphite rough blank 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 graphit