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US-20260125270-A1 - GRAPHITE MATERIAL AND PREPARATION METHOD THEREOF, ELECTROCHEMICAL DEVICE AND ELECTRONIC APPARATUS

US20260125270A1US 20260125270 A1US20260125270 A1US 20260125270A1US-20260125270-A1

Abstract

Disclosed are a graphite material and a method for preparing the same, an electrochemical device and an electronic apparatus. The graphite material satisfies the following conditions: La≤72 nm, Lc≤15 nm; wherein, La is a lattice constant of a graphite crystal in a 110 plane in the graphite material, Lc is a lattice constant of the graphite crystal in a 002 plane in the graphite material; F≥15 mN, F is a particle crushing force. The electrochemical device (especially lithium-ion battery) containing the same may ensure an excellent initial efficiency and fast-charging performance, while maintaining an excellent self-discharge performance, capacity performance and cycling performance.

Inventors

  • Shuyan Hou

Assignees

  • AESC JAPAN LTD.

Dates

Publication Date
20260507
Application Date
20250916
Priority Date
20241107

Claims (10)

  1. 1 . A graphite material, satisfying the following conditions: a. La≤72 nm, Lc≤15 nm; wherein La is a lattice constant of a graphite crystal in a 110 plane in the graphite material, and Lc is a lattice constant of the graphite crystal in a 002 plane in the graphite material; b. F≥15 mN, wherein F is a particle crushing force.
  2. 2 . The graphite material according to claim 1 , satisfying 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≤0.1, wherein S is a particle size distribution symmetry.
  3. 3 . The graphite material according to claim 1 , satisfying one or more of the following conditions a-d: a. a Dv50 particle size of the graphite material is 10 μm-13 μm; b. a sphericity of the graphite material is 0.5-1.0; c. a carbon content of the graphite material is greater than 99.9%, with a percentage being calculated as a mass percentage of the graphite material; d. the graphite material is microcrystalline graphite.
  4. 4 . A method for preparing the graphite material according to claim 1 , comprising the following steps: S1, conducting a first mixing by mixing a graphite precursor and a binder, adding a solvent to conduct a second mixing to obtain a mixture; wherein a temperature of the first mixing is 5° C.-20° C. below a softening point of the binder; S2, pressing the mixture to obtain a graphite green body; S3, laying the graphite green body on a surface layer of graphitization equipment, laying a graphitization insulation material on the graphite green body, conducting a graphitization treatment, the graphite green body obtaining graphitized graphite green body through the graphitization treatment; S4, conducting a crushing treatment on the graphitized graphite green body to obtain the graphite material.
  5. 5 . The method for preparing the graphite material according to claim 4 , wherein, in step S1, the temperature of the first mixing is 8° C.-15° C. below the softening point of the binder.
  6. 6 . The method for preparing the graphite material according to claim 4 , wherein step S1 satisfies one or more of the following conditions a-i: a. in step S1, a sphericity of the graphite precursor is 0.7-1.0; b. in step S1, the graphite precursor is natural microcrystalline graphite; c. in step S1, a fixed carbon content of the graphite precursor is 88%-91%, with a percentage being a mass percentage of the graphite precursor; d. in step S1, a Dv50 particle size of the graphite precursor is 6 μm-8 μm; e. in step S1, a mass ratio of the graphite precursor to the binder is (4-7): 1; f. in step S1, the binder comprises one or more of petroleum pitch, phenolic resin, epoxy resin, and coal tar; g. in step S1, the softening point of the binder is 100° C.-250° C.; h. in step S1, the solvent is selected from one or more of xylene, toluene, and n-hexane; i. in step S1, a solid content of the mixture is 40%-60%, with a percentage being calculated as a mass percentage of a solid ingredient of the mixture to a total mass of the mixture.
  7. 7 . The method for preparing the graphite material according to claim 4 , wherein step S1 and step S2 satisfy one or more of the following conditions a-d: a. in step S1, the method of performing the first mixing is stirring; b. in step S1, the method of performing the second mixing is stirring; c. in step S1, the method for preparing the graphite precursor comprises the following steps: conducting water washing and flotation on graphite ore, then conducting coarse crushing and a spheroidization treatment to obtain the graphite precursor; d. in step S2, the pressing is isostatic pressing.
  8. 8 . The method for preparing the graphite material according to claim 4 , wherein step S3 and step S4 satisfy one or more of the following conditions a-f: a. in step S3, a temperature of the graphitization treatment is greater than 1600° C.; b. in step S3, a time for the graphitization treatment is 18 hours to 40 hours; c. in step S3, the graphitization insulation material is petroleum coke and/or pitch coke; d. in step S3, the graphitization equipment is a graphitization furnace; e. in step S4, the crushing treatment further comprises sieving and magnetic purification; f. in step S4, the crushing treatment is crushing until a Dv50 particle size of particles is 10 μm-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 according to claim 1 .
  10. 10 . An electronic apparatus, comprising the electrochemical device according to claim 9 .

Description

CROSS-REFERENCE TO RELATED APPLICATION This application claims the priority benefit of China application serial no. 202411585430.4, filed on Nov. 7, 2024. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification. BACKGROUND Technical Field The present disclosure relates to a graphite material and a method for preparing the same, an electrochemical device, and an electronic apparatus. Description of Related Art Microcrystalline graphite is a type of natural graphite characterized by small unit cell and porous structure, which renders microcrystalline graphite greater kinetic advantages compared to conventional flake natural graphite, and higher capacity and compaction compared to conventional synthetic graphite. Furthermore, the raw material cost of microcrystalline graphite is significantly lower, approximately 20% to 30% of that of natural flake graphite of equivalent quality, thereby indicating promising application prospects. However, naturally mined microcrystalline graphite contains a high level of impurities, necessitating purification before being used as a negative electrode material in lithium-ion batteries. The purification treatment is complex, and the cost of impurity removal is approximately 2-3 times that of natural flake graphite of equivalent quality. Consequently, when considering the overall cost, microcrystalline graphite does not possess a cost advantage, significantly limiting the application potential thereof. Existing impurity removal technologies, such as those described in Chinese Patent Application No. CN107555426A, utilize acid-base and high-temperature heat treatment methods to purify microcrystalline graphite. Although these methods claim to be energy-efficient, the processing of waste acids and alkalis, along with the requirement for crucible furnaces, inevitably results in a substantial increase in costs. Additionally, these methods may compromise the structure of the graphite material, thereby impairing the initial efficiency and fast-charging performance of lithium-ion batteries containing such graphite. Chinese Patent Application No. CN109616640A describes a technique involving the coating of microcrystalline graphite by adding inorganic salts in a nitrogen atmosphere to improve the cycling performance of microcrystalline graphite. However, the experimental process is not suitable for large-scale mass production, and the high cost of experimental materials is not conducive to reducing the final product cost. Although the cycling performance of lithium-ion batteries using this microcrystalline graphite shows improvement, there are difficulties in ensuring an excellent initial efficiency and fast-charging performance. Therefore, developing methods that enable lithium-ion batteries containing graphite materials to ensure superior initial efficiency and fast-charging capabilities is crucial. SUMMARY In order to solve the problem that existing lithium-ion batteries containing graphite materials cannot ensure an excellent initial efficiency and fast-charging performance, the present disclosure provides a graphite material and a method for preparing the same, an electrochemical device and an electronic apparatus. The graphite material has extremely small La and Lc, relatively large particle crushing force F, and the electrochemical device (especially lithium-ion battery) containing the same may ensure an excellent initial efficiency and fast-charging performance, while also maintaining an excellent self-discharge performance, capacity performance and cycling performance. To achieve the above objectives, the present disclosure adopts the following technical solutions. In a first aspect, the present disclosure provides a graphite material, which satisfies the following conditions: a. La≤72 nm, Lc≤15 nm; wherein La is a lattice constant of a graphite crystal in a 110 plane in the graphite material, and Lc is a lattice constant of the graphite crystal in a 002 plane in the graphite material;b. F≥15 mN, wherein F is a particle crushing force. In a second aspect, the present disclosure provides a method for preparing the graphite material as described above, which includes the following steps: S1, conducting a first mixing by mixing a graphite precursor and a binder, adding a solvent to conduct a second mixing to obtain a mixture; wherein a temperature of the first mixing is 5° C.-20° C. below a softening point of the binder;S2, pressing the mixture to obtain a graphite green body;S3, laying the graphite green body on a surface layer of graphitization equipment, laying a graphitization insulation material on the graphite green body, conducting a graphitization treatment, the graphite green body obtaining graphitized graphite green body through the graphitization treatment;S4, conducting a crushing treatment on the graphitized graphite green body to obtain the graphite material. In a third aspect, the present