High-performance silicon/carbon anode nanocomposite and preparation method thereof

Abstract

The invention provides a high-performance silicon / carbon anode nanocomposite and a preparation method thereof. The high-performance silicon / carbon anode nanocomposite is characterized by containing carbon nano-spherical particles with mesoporous channels, and the spherical particles and / or the mesoporous channels are filled with elementary silicon particles. The prepared silicon / carbon anode nanocomposite is of a porous structure, the elementary silicon particles are dispersed in a carbon skeleton and the mesoporous channels, the volume expansion effect during lithium-ion charge and dischargeis low, and electrochemical cycle performance is stable.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery materials, and in particular relates to a preparation method of a high-performance silicon-carbon negative electrode material. Background technique [0002] In order to meet the energy demands of the new generation, the development of new electrode materials for lithium-ion batteries is necessary to meet the development of future electric vehicles and portable electronic devices. Since silicon is abundant in the earth's crust (26.4%, the second), it is environmentally friendly, and silicon and lithium can be alloyed at room temperature, with a specific capacity ten times that of commercial graphite electrode materials, so silicon-based negative electrodes It is the most potential next-generation anode material to replace graphite anode. However, the volume of silicon anode materials will change too much (300%) during the process of removing and intercalating lithium. After multiple cycles, the ...

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Problems solved by technology

This method is limited by the size of silicon powder and the dispersion process. The compounding of silicon and carbon is only a physical combination, and it is difficult to achieve uniform mixing on the molecular scale.

Patent Application No. 201710270902.0 Silicon-carbon anode material and its preparation method. In the silicon-carbon anode material and its preparation method, the surface of elemental silicon is first treated, and organic functional groups are grafted, and then mixed with modified worm-like graphene, and then another organic substance is introduced into the surface of elemental silicon Polymerization reaction of the organic functional groups of the silicon and graphene strengthens the chemical bonding between silicon and graphene. Although the negative electrode material obtained by this method has a high first-cycle specific capacity of 1764mAh / g, the preparation method is cumbersome. After the graphene is oxidized and modified The electrical conductivity of the material will deteriorate, and the introduction of various organic substances will affect the ion transmission, resulting in the attenuation of the kinetic properties of the material

[0006] The above research shows that these silicon-carbon anode materials are currently mixed with nano-silicon particles and various carbon substrates. progress, the bonding between silicon and carbon becomes increasingly poor, eventually leading to the separation of silicon and carbon materials, thus losing the point contact

And the particle size of elemental silicon used is more than 100nm. After multiple cycles, the SEI film thickens due to volume expansion, which reduces the long-term cycle stability.

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