High-capacity graphite negative electrode material and preparation method and application thereof

Abstract

The invention discloses a high-capacity graphite negative electrode material and a preparation method and application thereof, and the preparation method comprises the following steps: preparing crystalline flake graphite, a doped compound, a binder and a solvent into a mixed slurry, carrying out spray drying, crushing and spheroidizing to obtain spherical natural graphite of which the inner and outer surfaces are coated with the binder and the doped compound, and carrying out carbonization, demagnetization and screening to obtain the high-capacity graphite negative electrode material. The high-capacity graphite negative electrode material is obtained. The prepared high-capacity graphite negative electrode material has the advantages of high capacity, good cycle performance, good rate capability and the like, meanwhile, when the high-capacity graphite negative electrode material is 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 high-capacity graphite negative electrode material has very high use value and very good application prospects. The preparation method disclosed by the invention has the advantages of simple process, convenience in operation, low cost, low energy consumption and the like, is suitable for large-scale production and is beneficial to process application.

Description

technical field [0001] The invention belongs to the field of negative electrode materials, and relates to a high-capacity graphite negative electrode material and a preparation method and application thereof. Background technique [0002] Natural graphite has been widely used because of its high charge-discharge capacity, good charge-discharge platform, wide range of sources, and low cost. However, natural graphite has unstable structure, high internal porosity, and co-intercalation of solvent molecules, causing the layers to fall off and rupture during charging and discharging, exposing more surfaces that can react with the electrolyte, and accelerating the interaction between natural graphite and electrolysis. Lithium-ion batteries have disadvantages such as reduced charge and discharge efficiency, poor cycle performance, and poor safety, which directly reduce the cycle life of lithium-ion batteries. In addition, natural graphite still has the following shortcomings: the ...

AI Technical Summary

Problems solved by technology

However, natural graphite has unstable structure, high internal porosity, and co-intercalation of solvent molecules, causing the layers to fall off and rupture during charging and discharging, exposing more surfaces that can react with the electrolyte, and accelerating the interaction between natural graphite and electrolysis. Lithium-ion batteries have disadvantages such as reduced charge and discharge efficiency, poor cycle performance, and poor safety, which directly reduce the cycle life of lithium-ion batteries.

In addition, natural graphite also has the following shortcomings: the rate performance cannot meet the market demand; the gram capacity can no longer meet the higher energy density requirements of batteries

In order to overcome the above-mentioned shortcomings in natural graphite, a layer of amorphous carbon material is usually coated on the surface of natural graphite. However, the existing coating method mainly mixes natural graphite and coating modifier by physical mixing, Then in the carbonization process, using the liquefaction process of the coating modifier to make it flow and self-coating, there are the following defects: the coating modifier cannot effectively cover the outer surface of natural graphite, especially because the coating modifier is difficult to enter In the internal pores of spherical natural graphite, it is difficult to effectively cover the inner surface of spherical natural graphite, which makes it difficult for amorphous carbon materials to completely cover natural graphite, and finally makes the electrolyte during the battery cycle. Gradually penetrate into these uncoated natural graphite surfaces to continuously form a solid electrolyte interface (SEI) film, and the electrolyte is continuously embedded in the natural graphite layer structure, consuming a large amount of active lithium and destroying the natural graphite structure, resulting in continuous capacity decay

In addition, those skilled in the art have proposed strategies to increase the coating amount of amorphous carbon materials. Although increasing the coating amount of amorphous carbon materials can prevent natural graphite from reacting with the electrolyte to a certain extent, it is inevitable that the Reduce the capacity of natural graphite, resulting in the energy density of the material not meeting the requirements of use

Images