Carbon composite material, preparation method for carbon composite material and battery

Abstract

The invention relates to the field of batteries, in particular to a carbon composite material. The carbon composite material comprises a core, a middle layer covering the core, and an outer layer covering the middle layer, wherein the core is graphite; the middle layer is a silicon-based material or a tin-based material; and the outer layer is porous carbon. According to the carbon composite material, the silicon-based material or the tin-based material is positioned between the graphite and the porous carbon, so that the material pulverization can be inhibited; the porous carbon reserves sufficient space, so that the cyclic stress generated by expansion of the silicon-based material or the tin-based material can be buffered and the pulverization is avoided; and therefore, the carbon composite material has good cyclic performance. In addition, the porous carbon of the outer layer can effectively prevent the silicon-based material or the tin-based material from being in direct contact with an electrolyte solution, reduce the irreversible capacity and improve the conductive performance of the carbon composite material; and the porous carbon is favorable for insertion and extraction of lithium ions due to porosity. The invention furthermore discloses a preparation method for the carbon composite material and a battery.

Description

technical field

[0001] The invention relates to the field of batteries, in particular to a carbon composite material, a preparation method thereof and a battery. Background technique

[0002] Compared with traditional graphite anode materials, silicon has an ultra-high theoretical specific capacity (4200mAh / g) and a lower delithiation potential (<0.5V), and the voltage platform of silicon is slightly higher than that of graphite, which is not easy to charge when charging. The behavior of lithium precipitation on the surface occurs, and the safety performance is better, so it has become a new research direction for the negative electrode material of the battery.

[0003] However, since silicon is a semiconductor material, when it is used as a battery negative electrode material, its own conductivity is low, and the insertion and extraction of lithium ions in the process of charging and discharging will cause the volume of silicon to expand and shrink by more than 300%, whi...

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