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

Abstract

The invention provides a silicon-carbon composite negative electrode material for a lithium-ion battery and a preparation method thereof. The method includes steps: step 1, dispersing micron silicon in a solvent, and performing grinding to form nanometer silicon slurry; step 2, adding a carbon matrix, a binder and a conductive agent to the solvent for uniform mixing to obtain slurry 1, and addingthe nanometer silicon slurry in step 1 into the slurry 1 for uniform mixing to obtain slurry 2; step 3, drying the slurry 2 to obtain a precursor material 1, performing fusion on the precursor material 1 and a covering agent to obtain a precursor material 2, and placing the precursor material 2 in a protection atmosphere for thermal treatment to obtain a precursor material 3; step 4, crushing theprecursor material 3, mixing the crushed precursor material 3 with the covering agent, and performing high-temperature thermal covering to obtain a precursor material 4; and step 5, placing the precursor material 4 in the protection atmosphere for high-temperature carbonization treatment to obtain the silicon-carbon composite negative electrode material. According to the material and the preparation method thereof, the silicon-loaded carbon matrix is wrapped by conductive carbon so that direct contact of the silicon negative electrode and electrolyte is isolated, and the cycle performance of the battery is enhanced.

Description

technical field [0001] The invention belongs to the field of negative electrode materials for lithium ion batteries, and relates to a silicon-carbon composite negative electrode material for lithium ion batteries and a preparation method thereof. Background technique [0002] At present, graphite-based carbon materials, such as artificial graphite, natural graphite, soft carbon, and hard carbon, are mainly used as anode materials for lithium-ion batteries. However, the discharge specific capacity of graphite-based negative electrode materials is low (372mAh / g), which cannot meet the development requirements of lithium-ion batteries for high capacity and small volume. Therefore, people are trying their best to find a negative electrode material with high specific capacity that can replace the graphite negative electrode. Among many negative electrode materials, the theoretical specific capacity of silicon is 4200mAh / g, which is much higher than that of graphite negative elec...

AI Technical Summary

Problems solved by technology

However, the liquid-phase coating is not complete in this method, and some nano-silicon is still exposed, which is in direct contact with the electrolyte, resulting in poor cycle performance of the material.

At the same time, when water is used as a solvent, the dispersibility of silicon is poor. When spraying at high temperature, nano-silicon is severely oxidized, resulting in a low efficiency of the material for the first time.

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