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CN-122000310-A - Graphite material, preparation method thereof, electrochemical device and electronic equipment

CN122000310ACN 122000310 ACN122000310 ACN 122000310ACN-122000310-A

Abstract

The invention discloses a graphite material, a preparation method thereof, an electrochemical device and electronic equipment. The graphite material comprises an inner core and an outer shell, wherein the inner core comprises first graphite, the outer shell comprises second graphite, the graphite material meets the following conditions that 6<K is less than or equal to 30, K is a shape coefficient, F is more than or equal to 1.06 and less than or equal to 1.12, F is a pressure-resistant coefficient, L is more than or equal to 0 and less than or equal to 2, and L is bulk phase porosity. The graphite material provided by the invention has good compaction density, and has good quick charge performance and cycle performance when being applied to a battery.

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. The graphite material is characterized by comprising an inner core and an outer shell, wherein the material of the inner core comprises first graphite, and the material of the outer shell comprises second graphite; The graphite material satisfies the following conditions: 6<K is less than or equal to 30, K is a shape coefficient; f is more than or equal to 1.06 and less than or equal to 1.12, F is a withstand voltage coefficient; L is more than or equal to 0 and less than or equal to 2 percent, and L is the bulk phase porosity.
  2. 2. The graphite material of claim 1, wherein the graphite material satisfies one or more of the following conditions (a) - (c): (a)6<K≤20; (b) L is more than or equal to 0 and less than or equal to 1.6 percent; and, a step of, in the first embodiment, (c)1.06≤F≤1.10。
  3. 3. The graphite material of claim 1, wherein the graphite material satisfies one or both of the following conditions (a) - (b): (a) The graphite material has a particle size D V of 7 μm to 13 μm, and, (B) The thickness of the shell is 50nm-100nm.
  4. 4. A method of preparing a graphite material according to any one of claims 1 to 3, comprising the steps of: (1) Hydroxylating the second graphite raw material to obtain a second graphite matrix; hydroxylation treatment is carried out on the first graphite raw material to obtain a first graphite matrix; (2) Calcining the mixture comprising the second graphite matrix and the first graphite matrix 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 second graphite raw material meets the following conditions that La is less than or equal to 72 nm and Lc is less than or equal to 15 nm, wherein La is the lattice constant of graphite crystals in the second graphite raw material on the 110 plane, lc is the lattice constant of graphite crystals in the second graphite raw material on the 002 plane, F1 is more than or equal to 15 mN, and F1 is the crushing force of particles; (b) The second 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 second graphite raw material; (c) The first graphite raw material satisfies that the bulk phase porosity is less than or equal to 0.5 percent, and, (D) The preparation method of the first graphite raw material comprises the following steps of sequentially carrying out full forging treatment, degassing, pressing and graphitization treatment on petroleum needle coke to obtain the first graphite raw material.
  6. 6. The method of preparing a graphite material as recited in claim 5, wherein the method of preparing the first graphite substrate satisfies one or more of the following conditions (a) - (d): (a) Volatile matter V <5% of the petroleum needle coke; (b) The degassing time is 1h-3h; (c) The pressing mode is isostatic pressing, the isostatic pressing pressure is 100 MPa-300 MPa, the isostatic pressing time is 18-36 h, and, (D) The temperature of the degassing is 450-800 ℃.
  7. 7. 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) - (f): (a) The treating agent used in the hydroxylation treatment is an alkali solution; (b) The temperature of the hydroxylation treatment is 50-65 ℃; (c) The mass ratio of the second graphite matrix to the first graphite matrix is (0.02-0.1): 1; (d) The calcination temperature is 900-1200 ℃; (e) The calcination time is 6 to 10 hours, and, (F) In step (2), the mixture further comprises a binder, a solvent, and a surfactant.
  8. 8. The method of claim 7, wherein in step (2), the mixture satisfies one or more of the following conditions (a) - (e): (a) The binder is liquid petroleum asphalt and/or phenolic resin, and the coking value of the liquid petroleum asphalt is less than 25%; (b) The volume ratio of the binder to the solvent is (5-10): 1; (c) The mass ratio of the binder to the first graphite matrix is (3-10) 100; (d) The surfactant is dodecyl trimethyl ammonium bromide; (e) The mass ratio of the first graphite matrix to the surfactant is 1 (0-0.002) and is not 0.
  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 artificial graphite has the remarkable advantages of excellent cycle performance, high-rate charge-discharge efficiency, electrolyte compatibility and the like, and is widely applied to the fields of power batteries for vehicles and medium-high-end electronic products. However, the capacity of the artificial graphite is difficult to break through 360mAh/g, if the quick charge performance is considered, the capacity is difficult to break through 355 mAh/g, the compaction of the artificial graphite is difficult to break through 1.70g/cc -1 after the artificial graphite is made into a pole piece, and the dynamics is extremely poor even if the artificial graphite is forced to be done. In the prior art, if CN 112582592A adopts a liquid phase coating method to treat graphite, although the quick charge performance is improved, the capacity is basically deteriorated, the compaction and high temperature performance are improved, and CN115621443 a improves the quick charge by coating graphene, but the cost and the processing difficulty are increased, and the quick charge is not lost. Although the microcrystalline graphite has good dynamic characteristics, the defect of poor high-temperature performance can be overcome by ultrahigh-temperature treatment, and a large amount of fine powder is removed by shaping to obtain proper compaction, so that the yield of the microcrystalline graphite is reduced, the cost is increased, and therefore, the fine powder is required to be reasonably utilized, and the added value of a product is increased. Disclosure of Invention The invention mainly aims to overcome the defect that artificial graphite in the prior art is difficult to simultaneously have good quick charge performance and good cycle performance when applied to a battery, and provides a graphite material, a preparation method thereof, an electrochemical device and electronic equipment. The graphite material provided by the invention has good compaction density, and has good quick charge performance and cycle performance when being applied to a battery. In a first aspect, the present invention provides a graphite material comprising an inner core and an outer shell, the material of the inner core comprising a first graphite and the material of the outer shell comprising a second graphite; The graphite material satisfies the following conditions: 6<K is less than or equal to 30, K is a shape coefficient; f is more than or equal to 1.06 and less than or equal to 1.12, F is a withstand voltage coefficient; L is more than or equal to 0 and less than or equal to 2 percent, and L is the bulk phase porosity. In a second aspect, the present invention provides a method of preparing a graphite material as described above, comprising the steps of: (1) Hydroxylating the second graphite raw material to obtain a second graphite matrix; hydroxylation treatment is carried out on the first graphite raw material to obtain a first graphite matrix; (2) Calcining the mixture comprising the second graphite matrix and the first graphite matrix 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: the graphite material with the core-shell structure has the advantages of low shape factor, bulk phase porosity and good pressure resistance coefficient, has high compaction density, cohesiveness and processability, and has good quick charge performance and cycle performance when applied to an electrochemical device (especially a lithium ion battery). Detailed Description Graphite material The graphite material provided by the first aspect of the invention comprises an inner core and an outer shell, wherein the material of the inner core comprises first graphite; The graphite material satisfies the following conditions: 6<K is less than or equal to 30, K is a shape coefficient; f is more than or equal to 1.06 and less than or equal to 1.12, F is a withstand voltage coefficient; L is more than or equal to 0 and less than or equal to 2 percent, and L is the bulk phase porosity. In the invention, the sh