A fast-charging artificial graphite negative electrode material and a preparation method thereof

Abstract

The application provides a kind of fast charging type artificial graphite negative electrode material and its preparation method, belongs to lithium ion battery negative electrode material technical field.The preparation method includes: after mixing salt and graphite precursor uniformly, pre-carbonization treatment is carried out, after washing, drying, the pre-carbonization product is graphitized, and artificial graphite is obtained;The artificial graphite is coated with a coating agent in a liquid phase to obtain coated artificial graphite powder;The coated artificial graphite powder is carbonized to obtain a fast charging type artificial graphite negative electrode material.The graphitization degree of the fast charging type artificial graphite negative electrode material obtained by the application can be adjusted in the range of 83% to 92%, the average discharge specific capacity at 0.1C can be adjusted in the range of 320 to 390mAh / g, the specific capacity at 3C can be adjusted in the range of 130 to 240mAh / g, and the specific capacity at 5C can be adjusted in the range of 50 to 150mAh / g.The preparation method used by the application is simple, easy to operate, and suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery anode material technology, specifically relating to a fast-charging artificial graphite anode material and its preparation method. Background Technology

[0002] With the increasing demands for faster charging speeds in industries such as 3C electronics, energy storage, new energy, and 5G terminals, the main technologies for shortening lithium-ion battery charging time are high-voltage charging and high-current charging. High-voltage charging places high demands on lithium-ion battery design, leading to slow market adoption. In contrast, high-current charging is a more readily achievable approach, and the rate charge / discharge performance of the anode material is crucial for improving the fast-charging performance of lithium-ion batteries. Commonly used fast-charging graphite materials are prepared through graphite modification, coating, and blending different types of graphite. For example, coating the graphite surface with an amorphous carbon layer can improve the rate charge / discharge performance of the graphite anode, but the improvement is limited. Carbon coating after graphite modification through oxidation, alkali activation, and intercalation can effectively improve the fast-charging performance of the graphite anode, but oxidation has limited improvement on interlayer spacing, and excessive oxygen functional groups can worsen cycle life. Intercalation inevitably introduces metal heteroatoms, which are difficult to remove and cause leakage current. Alkali activation places higher demands on equipment and introduces more defects, resulting in higher irreversible capacity. The combination of artificial graphite and natural graphite can improve the high-current charging and discharging performance to a certain extent, but it also introduces the drawbacks of natural graphite into artificial graphite. Summary of the Invention

[0003] To overcome the shortcomings of existing methods for preparing fast-charging artificial graphite anode materials and solve the technical problem hindering the charging and discharging speed of fast-charging artificial graphite, this invention provides a method for preparing fast-charging artificial graphite anodes based on precursor modification. This method is simple to prepare, easy to scale up industrially, applicable to a wide range of raw materials, and has cost advantages.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0005] A method for preparing a fast-charging artificial graphite anode material includes the following steps:

[0006] (1) Mix the graphite precursor and salt in a certain proportion to obtain mixture A;

[0007] (2) The mixture A was pre-carbonized, and after washing and drying, the pre-carbonized product B was obtained.

[0008] (3) Graphitize the pre-carbonized product B to obtain artificial graphite C;

[0009] (4) Artificial graphite C and coating agent are mixed in proportion and dissolved in solvent for liquid phase coating to obtain coated artificial graphite powder;

[0010] (5) Carbonize the coated artificial graphite powder to obtain fast-charging artificial graphite anode material.

[0011] Preferably, in step (1), the graphite precursor is one or more of coal, semi-coke, pitch coke, needle coke, petroleum coke, and carbon black; and the salt is a halide salt.

[0012] Preferably, in step (1), the mass ratio of graphite precursor to salt is 1:0.5 to 1:20.

[0013] Preferably, the temperature of the pre-carbonization treatment in step (2) is 700-1200℃, the atmosphere is one of argon, nitrogen, argon / hydrogen mixture, or nitrogen / hydrogen mixture, and the holding time is 1-6h.

[0014] Preferably, the graphitization temperature in step (3) is 2500-3000℃, and the holding time is 1-8h.

[0015] Preferably, in step (4), the coating agent is one or more of hard carbon-containing organic precursors and soft carbon-containing organic precursors; the solvent is one or more of water, ethanol, furan, pyridine, and dimethylformamide.

[0016] Preferably, in step (4), the mass ratio of artificial graphite C to coating agent is 100:1 to 100:40.

[0017] Preferably, the carbonization temperature in step (5) is 800-1500℃, the atmosphere is one of argon, nitrogen, argon / hydrogen mixture, or nitrogen / hydrogen mixture, and the holding time is 2-6h.

[0018] A fast-charging artificial graphite anode material prepared by the method described above significantly improves the fast-charging performance of artificial graphite by using salt-assisted carbonization to create pores.

[0019] A lithium-ion battery comprising the fast-charging artificial graphite anode material as described above.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) During the pre-carbonization process of graphite precursor, halide salts block the rearrangement of carbon microcrystalline structure and generate structural defects. These defects are conducive to the formation of short-range graphene clusters and large interlayer spacing structure in the subsequent graphitization process, thereby maintaining high electrical conductivity while ensuring rapid lithium ion intercalation.

[0022] (2) Most of the halogen salts used have the effect of molten salt assisted pore formation. During the subsequent removal of molten salt, large pores will be left in the pre-carbonized sample. Some of these large pores are consumed in the subsequent graphitization process, while others are retained. Therefore, their effect on improving the relative surface area is limited, but they can effectively accelerate the diffusion process of lithium ions in artificial graphite.

[0023] (3) Compared with traditional alkali activation pore formation, the halide salt used in this invention will not pyrolyze and volatilize within the pre-carbonization temperature range. Therefore, the cleaning solution of the pre-oxidized sample contains a large amount of dissolved halide salt, which can be reused through crystallization, providing a new approach for low-cost preparation of fast-charging artificial graphite anodes. Attached Figure Description

[0024] Figure 1 The image shows a SEM image of the fast-charging graphite material obtained in Example 1.

[0025] Figure 2 X-ray diffraction pattern (including silicon standard) of the fast-charging artificial graphite material prepared in Example 1;

[0026] Figure 3 This is a scaling factor diagram of the artificial graphite anode material prepared in Example 1. Detailed Implementation

[0027] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0028] Example 1

[0029] A method for preparing a fast-charging artificial graphite anode material includes the following steps: 1) Ball milling 10g of semi-coke and 100g of sodium chloride to obtain mixture A; 2) Pre-carbonizing mixture A in nitrogen at 800℃ for 2h, cooling to room temperature, washing the pre-carbonized sample with warm water, drying to obtain B, collecting the dissolved sodium chloride after recrystallization, and reusing it; 3) Graphitizing B at 2800℃ for 1h to obtain C; 4) Mixing 5g of C with 0.5g of sucrose in water in the liquid phase, drying to obtain coated C; 5) Carbonizing coated C in nitrogen at 1000℃ for 2h to obtain the fast-charging artificial graphite anode material.

[0030] Figure 1 and Figure 2 The images shown are SEM images and XRD patterns of the fast-charging artificial graphite material obtained in Example 1. The graphitization degree of the obtained fast-charging artificial graphite is 89%. Figure 3Electrochemical tests show that the obtained fast-charging artificial graphite anode material has a reversible capacity of 384 mAh / g at 0.1C, a specific capacity of 336 mAh / g at 1C, and specific capacities of 230 mAh / g and 117 mAh / g at 3C and 5C, respectively.

[0031] Example 2

[0032] A method for preparing a fast-charging artificial graphite anode material includes the following steps: 1) 10g of pitch coke and 150g of sodium chloride are ball-milled and mixed to obtain mixture A; 2) Mixture A is pre-carbonized in nitrogen at 900℃ for 2h, cooled to room temperature, washed with warm water, dried to obtain B, and the dissolved potassium chloride is collected after recrystallization and reused; 3) B is graphitized at 2900℃ for 2h to obtain C; 4) 5g of C and 0.5g of pitch are mixed in a liquid phase in furan and dried to obtain coated C; 5) Coated C is carbonized in a nitrogen / hydrogen mixture at 1000℃ for 2h to obtain the fast-charging artificial graphite anode material.

[0033] The obtained fast-charging artificial graphite anode material has a graphitization degree of 86%, a reversible capacity of 364 mAh / g at 0.1C, a specific capacity of 316 mAh / g at 1C, and specific capacities of 223 mAh / g and 142 mAh / g at 3C and 5C, respectively.

[0034] Example 3

[0035] A method for preparing a fast-charging artificial graphite anode material includes the following steps: 1) 10g of anthracite and 50g of calcium chloride are ball-milled and mixed to obtain mixture A; 2) Mixture A is pre-carbonized in nitrogen at 900℃ for 2h, cooled to room temperature, washed with warm water, dried to obtain B, and the dissolved calcium chloride is collected after recrystallization and reused; 3) B is graphitized at 2800℃ for 3h to obtain C; 4) 5g of C and 0.5g of phenolic resin are liquid-phase mixed in ethanol, dried to obtain coated C; 5) Coated C is carbonized in argon at 1000℃ for 3h to obtain the fast-charging artificial graphite anode material.

[0036] The obtained fast-charging artificial graphite anode material has a graphitization degree of 90%, a reversible capacity of 356 mAh / g at 0.1C, a specific capacity of 310 mAh / g at 1C, and specific capacities of 236 mAh / g and 136 mAh / g at 3C and 5C, respectively.

[0037] Example 4

[0038] A method for preparing a fast-charging artificial graphite anode material includes the following steps: 1) Ball milling 10g of petroleum coke and 60g of sodium chloride to obtain mixture A; 2) Pre-carbonizing mixture A in nitrogen at 1000℃ for 1h, cooling to room temperature, washing the pre-carbonized sample with warm water, drying to obtain B, collecting the dissolved sodium chloride after recrystallization, and reusing it; 3) Graphitizing B at 2600℃ for 4h to obtain C; 4) Mixing 5g of C with 0.5g of polyvinyl alcohol in water in the liquid phase, drying to obtain coated C; 5) Carbonizing coated C in argon at 800℃ for 4h to obtain the fast-charging artificial graphite anode material.

[0039] The obtained fast-charging artificial graphite anode material has a graphitization degree of 85%, a reversible capacity of 336 mAh / g at 0.1C, a specific capacity of 280 mAh / g at 1C, and specific capacities of 206 mAh / g and 103 mAh / g at 3C and 5C, respectively.

[0040] Example 5

[0041] A method for preparing a fast-charging artificial graphite anode material includes the following steps: 1) Ball milling 10g of semi-coke and 60g of sodium chloride to obtain mixture A; 2) Pre-carbonizing mixture A in nitrogen at 800℃ for 2h, cooling to room temperature, washing the pre-carbonized sample with warm water, drying to obtain B, collecting the dissolved sodium chloride after recrystallization, and reusing it; 3) Graphitizing B at 2700℃ for 4h to obtain C; 4) Liquid-phase mixing 5g of C and 1g of polyacrylonitrile in dimethylformamide, drying to obtain coated C; 5) Carbonizing coated C in argon at 1200℃ for 2h to obtain the fast-charging artificial graphite anode material.

[0042] The obtained fast-charging artificial graphite anode material has a graphitization degree of 88%, a reversible capacity of 336 mAh / g at 0.1C, a specific capacity of 318 mAh / g at 1C, and specific capacities of 218 mAh / g and 140 mAh / g at 3C and 5C, respectively.

[0043] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a fast-charging artificial graphite anode material, characterized in that, Includes the following steps: (1) Mix the graphite precursor and salt in a certain proportion to obtain mixture A; (2) Mixture A is pre-carbonized, and after washing and drying, pre-carbonized product B is obtained; (3) Graphitize the pre-carbonized product B to obtain artificial graphite C; (4) Mix artificial graphite C with a coating agent in a certain proportion and dissolve in a solvent for liquid phase coating to obtain coated artificial graphite powder; (5) Carbonize the coated artificial graphite powder to obtain fast-charging artificial graphite anode material; The salt is brine; In step (1), the mass ratio of graphite precursor to salt is 1:0.5 ~ 1:

20.

2. The preparation method of a fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step (1), the graphite precursor is one or more of coal, semi-coke, pitch coke, needle coke, petroleum coke, and carbon black; the salt is a halide salt.

3. The method for preparing a fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step (2), the pre-carbonization treatment temperature is 700 ~ 1200℃, the atmosphere is one of argon, nitrogen, argon / hydrogen mixture, or nitrogen / hydrogen mixture, and the holding time is 1 ~ 6 h.

4. The method for preparing a fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step (3), the graphitization temperature is 2500 ~ 3000℃ and the holding time is 1 ~ 8 h.

5. The method for preparing a fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step (4), the coating agent is one or more of hard carbon-containing organic precursors and soft carbon-containing organic precursors; the solvent is one or more of water, ethanol, furan, pyridine, and dimethylformamide.

6. A method for preparing a fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step (4), the mass ratio of artificial graphite C to coating agent is 100:1 ~ 100:

40.

7. A method for preparing a fast-charging artificial graphite anode material as described in claim 1, characterized in that, In step (5), the carbonization temperature is 800 ~ 1500℃, the atmosphere is one of argon, nitrogen, argon / hydrogen mixture, or nitrogen / hydrogen mixture, and the holding time is 2 ~ 6 h.

8. A fast-charging artificial graphite anode material prepared by the preparation method according to any one of claims 1 to 7, characterized in that, Salt-assisted carbonization is used to create pores, which significantly improves the fast-charging performance of artificial graphite.

9. A lithium-ion battery, characterized in that, Including the fast-charging artificial graphite anode material as described in claim 8.

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