High-capacity rapid charge graphite negative electrode material and preparation method thereof

Abstract

The invention provides a preparation method of a high-capacity rapid charge graphite negative electrode material. According to the method, easily-graphitized coke / high-crystallinity graphite and difficultly-graphitized coke / hard carbon are secondarily granulated, asphalt is mixed to perform composite reaction, mixture is crushed after the composite reaction, the crushed mixture is graphitized, andthe graphitized mixture is modified and carbonized. The negative electrode material prepared by the method takes secondary granules serve as a core, the surfaces of the negative electrode material are wrapped by double layers, and the negative electrode material has the advantages of high capacity and good rapid charge performance and solves the problem that the capacity and rapid charge performance cannot be taken into account in the prior art.

Description

technical field [0001] The invention relates to a carbon material and a preparation method thereof, in particular to a lithium ion battery negative electrode material and a preparation method thereof. Background technique [0002] Graphite anode material has the characteristics of high energy density, good cycle performance, mature preparation technology, and low manufacturing cost. It is the mainstream commercial anode material for lithium-ion batteries; In order to meet the higher requirements, it is generally hoped to improve the fast charging ability at room temperature and low temperature, so that the graphite anode material must be specially designed and processed to meet the fast charging requirements. [0003] People usually use particle design and surface modification methods to further improve the fast charging performance. The common ideas are as follows: ① The carbon material is crushed to a certain particle size, and the secondary granulation is achieved by knea...

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Problems solved by technology

[0003] People usually use particle design and surface modification methods to further improve the fast charging performance. The common ideas are as follows: ① The carbon material is crushed to a certain particle size, and the secondary granulation is achieved by kneading, and finally a secondary particle is obtained by graphitization The structure of graphite anode material; the defect of this structure is that it is difficult to balance capacity and fast charging performance. If you choose easy graphitization raw materials, the capacity can be guaranteed but the fast charging performance is poor; if you choose difficult graphitization raw materials, the fast charging performance is relatively poor. Good but low capacity; after graphitization treatment, the particle surface is highly ordered, which also has a great negative impact on fast charging performance

②The carbon material is pulverized to a certain particle size, and finally carbonized through surface modification to obtain a graphite anode material with a primary particle structure; the defect of this structure is that it is difficult to increase the capacity without graphitization treatment, although surface modification can reduce The interface impedance improves the fast charging performance, but due to the long diffusion path of the primary particle structure, it has a certain negative impact on the fast charging performance

[0004] Patent document 201410784385.5 discloses a fast-charging graphite lithium-ion battery negative electrode material and its preparation method. After mixing natural graphite and pitch - kneading - high-temperature graphitization treatment, a composite graphite material with a secondary particle structure is obtained. Natural graphite is selected as the raw material capacity Easy to guarantee but can not meet the high rate fast charge

[0005] Patent document 201410787061.7 discloses a fast-charging graphite lithium-ion battery negative electrode material and its preparation method. Petroleum coke / pitch coke and pitch are mixed-kneaded-high-temperature graphitization to obtain an artificial graphite material with a secondary particle structure. Due to the petroleum coke / Pitch coke is not the artificial graphite raw material with the highest capacity, nor is it the artificial graphite raw material with the best fast charging performance, so capacity and fast charging performance cannot be taken into account

[0006] Patent document 201711463778.6 discloses a graphite anode material for fast-charging lithium-ion batteries and its preparation method. After mixing carbon material and pitch - kneading - carbonization - high-temperature graphitization, a composite graphite material with a secondary particle structure is obtained. Due to the high degree of ordering of the particle surface after graphitization, it has a negative impact on the fast charging performance

[0007] The common problem in the above-mentioned patent documents is that there is no optimal combination of raw materials, and the particle surface is highly ordered after graphitization treatment, which cannot give consideration to both capacity and fast charging performance.

[0008] Patent document 201610729568.6 discloses a secondary battery negative electrode material, its preparation method and a battery containing the negative electrode material, using a high molecular polymer as a binder to uniformly coat a layer of small particles on the surface of the existing negative electrode active material Carbonaceous materials, the anode materials of secondary batteries obtained after carbonization treatment, lack of graphitization process, the existence of polymer pyrolysis carbon and small particles of conductive carbon have a certain negative impact on capacity

[0009] Patent document 201710683450.9 discloses a fast-charging graphite anode material and its preparation method. By mixing graphite precursors with coating materials, low-temperature treatment and high-temperature graphitization treatment, there is no secondary granulation process and surface modification process, and the diffusion path The improvement of interface impedance and interface impedance is limited, and the fast charging performance cannot be significantly improved.

[0010] The common problem in the above-mentioned patent documents is that there is no optimal combination of raw materials, all of which are primary particle structures, and the capacity and fast charging performance cannot be taken into account.

[0011] Judging from the current situation, none of the existing technologies has achieved satisfactory results from the perspective of industrialization, and none of them can effectively balance capacity and fast charging performance

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