Silicon-carbon negative electrode material for lithium ion battery and preparation method

Abstract

The invention belongs to the field of lithium ion battery negative electrode materials and electrochemistry, and particularly relates to a silicon-carbon negative electrode material for a lithium ionbattery and a preparation method thereof. The negative electrode material is of a core-shell structure, wherein the core is nano silicon, cracked carbon and a single-walled carbon nanotube, and the shell is a carbon coating layer formed by vapor deposition; the particle size of the nano silicon is 5-100 nm; the softening point of cracked carbon is less than 300 DEG C, and the residual carbon rateis more than 40%; the diameter of the single-walled carbon nanotube is 5-20 nm, preferably 5-10 nm; the tube length is 30 to 500 nm, preferably 30 to 100 nm; and the thickness of the carbon coating layer is 10-200 nm. The preparation method comprises the following steps: (1) carrying out homogeneous compounding on a cracked carbon precursor and the single-walled carbon nanotube; (2) depositing nano silicon CVD in the cracked carbon; (3) carrying out mechanical shaping; and (4) carrying out carbon coating. The silicon-carbon negative electrode material prepared by the method is simple in process, excellent in performance and environment-friendly.

Description

technical field [0001] The invention belongs to the field of negative electrode materials and electrochemistry of lithium ion batteries, and in particular relates to a silicon carbon negative electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] In recent years, with the development of science and technology and the improvement of people's living standards, people have put forward higher requirements for lithium-ion batteries, such as longer service life and lighter weight. However, the theoretical specific capacity of conventional graphite anode materials is only It is 372mAh / g, which can no longer meet the needs of high specific capacity batteries, so the development of high-performance new electrode materials has become a research hotspot. Silicon has an ultra-high theoretical specific capacity (4200mAh / g) and a low delithiation potential (<0.5V), and the voltage platform of silicon is slightly higher than that of ...

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Problems solved by technology

[0002] In recent years, with the development of science and technology and the improvement of people's living standards, people have put forward higher requirements for lithium-ion batteries, such as longer service life and lighter weight. However, the theoretical specific capacity of conventional graphite anode materials is only It is 372mAh / g, which can no longer meet the needs of high specific capacity batteries, so the development of high-performance new electrode materials has become a research hotspot

Silicon has an ultra-high theoretical specific capacity (4200mAh / g) and a low delithiation potential (<0.5V), and the voltage platform of silicon is slightly higher than that of graphite. It is difficult to cause lithium precipitation on the surface during charging, and the safety performance is better. However, during the charging and discharging process of the battery, the intercalation and extraction cycle of lithium will cause a huge change in the volume of silicon, and the serious volume expansion and contraction of silicon will cause the destruction of the material structure and the pulverization of the material, which will lead to a decrease in the cycle performance of lithium-ion batteries. the sharp decline of

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