Graphite negative electrode material and preparation method and application thereof

Abstract

The invention discloses a graphite negative electrode material as well as a preparation method and application thereof, and the graphite negative electrode material is prepared by the following method: mixing crystalline flake graphite, a catalyst, a binder and a solvent to prepare mixed slurry, and performing spray drying on the obtained mixed slurry to obtain the graphite negative electrode material. And crushing and spheroidizing the obtained material with the binder and the catalyst mixed and coated on the surface of the crystalline flake graphite, graphitizing the obtained spherical natural graphite with the binder and the catalyst coated on the inner surface and the outer surface, and performing demagnetizing and screening to obtain the graphite negative electrode material. The prepared graphite negative electrode material comprises the spherical natural graphite, the inner surface and the outer surface of the graphite negative electrode material are uniformly coated with the artificial graphite layers, an electrolyte can be effectively prevented from being in contact with the natural graphite, the cycle performance of the material is improved, and the graphite negative electrode material has the advantages of high graphitization degree, high capacity, good cycle performance and the like and can be prepared into a working electrode for preparing a lithium ion battery; the cycle life of the lithium ion battery can be remarkably prolonged, and the lithium ion battery has very high use value and a very good application prospect.

Description

technical field [0001] The invention belongs to the field of negative electrode materials, and relates to a graphite negative electrode material and a preparation method and application thereof. Background technique [0002] Carbon materials have the advantages of high capacity, good reversibility of intercalation / delithiation, low potential platform, and excellent cycle performance. They are the main anode materials for 3C electronic products and have been widely used, and gradually expanded to electric vehicles (EV) and hybrid Power supply for electric vehicles (HEV). Therefore, it is crucial to develop and apply high-performance electrode materials. At present, lithium-ion batteries mainly use graphite materials as negative electrode materials. Traditional graphite-based negative electrode materials have problems such as poor cycle and poor rate performance during their cycle. [0003] Natural graphite is widely used because of its high charge-discharge capacity, good c...

AI Technical Summary

Problems solved by technology

In this patented technology, there are defects: the binder cannot be filled into the interior of natural graphite during the mixing process, resulting in the inability to form an artificial graphite coating layer in the interior of natural graphite during the graphitization process. Therefore, during the battery cycle, Due to the failure to effectively coat the interior of natural graphite, the natural graphite negative electrode material will have a side reaction with the electrolyte, resulting in poor cycle performance of the battery

In this patented technology, the existing defects are: impregnation of asphalt under high temperature and high pressure conditions, there are defects such as complicated preparation process, high energy consumption, and high production cost; at the same time, since the asphalt package on the surface is rinsed with organic solvent This makes the asphalt layer coated on the surface easy to be washed off, resulting in too thin or even no asphalt coating layer on the surface of natural graphite, which makes it difficult for the artificial graphite layer to effectively coat the surface of natural graphite. Similarly, The internal pores of the natural graphite used are closed pores or the pores are too small, which will also make the coating effect of the artificial graphite on the inner surface of the natural graphite poor, and it is difficult to achieve an effective coating of the artificial graphite layer on the inner surface of the natural graphite. Therefore, in the battery cycle process However, due to the failure to effectively coat the inner and outer surfaces of natural graphite, the natural graphite negative electrode material will have a side reaction with the electrolyte, resulting in poor cycle performance of the battery.

In this patented technology, there are defects: the cycle performance of the obtained natural graphite negative electrode material is poor, the reasons may be, one is that the self-pressurization method is difficult to realize the coating modifier in the natural graphite due to the closed pores or the pores are too small. The effective filling inside the natural graphite makes it difficult for the inner surface of the natural graphite to be evenly coated by the coating modifier, which makes the coating effect of the artificial graphite layer on the inner surface of the natural graphite poor, and the possibility of the inner surface of the natural graphite being exposed The second is that after heat treatment, the material is crushed and classified. This operation is relatively easy to cause the soft carbon coating layer to fall off, resulting in the exposure of natural graphite; at the same time, this method requires high temperature and high pressure equipment, which is not conducive to industrialization

Images