Graphene-silicon composite lithium ion battery negative electrode and preparation method thereof

Abstract

The invention provides a graphene-silicon composite lithium ion battery negative electrode and a preparation method thereof. The graphene-silicon composite lithium ion battery negative electrode is characterized by comprising copper foil and a multi-layer structure arranged on the copper foil, the multi-layer structure comprises graphene layers and silicon-carbon nanotube layers which are arrangedat intervals, and each silicon-carbon nanotube layer comprises silicon nanoparticles and carbon nanotubes, wherein the silicon nanoparticles are coated with the carbon nanotubes. The laminar composite can be applied to a lithium ion battery by serving as a negative electrode material. The negative electrode material has the advantages of being high in specific capacity, stable in cycling performance and the like. By means of the simple step, the silicon nanoparticles are successfully coated with the graphene and the carbon tubes, the volume effect of the silicon material in the charging and discharging process is improved through the laminar special structure, and the conductivity of the electrode is improved by means of the condition of the graphene and the carbon nanotubes, so that theelectrode material is high in specific capacity and coulomb efficiency and good in cycling performance finally.

Description

technical field [0001] The invention relates to a graphene / silicon composite lithium ion battery negative electrode and a preparation method thereof. Background technique [0002] Lithium-ion batteries have the characteristics of high capacity, long cycle life, no pollution, good safety, etc., and have been more and more used in the field of portable electronic products and power batteries. Driven by the development of electric vehicles and the exploration of renewable resources, research on chemical power sources requires higher energy storage and energy conversion equipment, as well as high specific energy, high specific power, and long life. However, there are still many deficiencies in commercial lithium-ion batteries. The negative electrode material of lithium-ion batteries is the key factor affecting battery performance. The current commercial lithium-ion batteries mostly use carbonaceous negative electrodes such as graphite, and their theoretical capacity is 372mAh / g....

AI Technical Summary

Problems solved by technology

By making graphene and silicon materials into a layered structure, the flexibility of graphene can be fully utilized, and the layered coating structure brought by the high surface area can reduce the powdering of electrode materials during the expansion and contraction of silicon. The layered structure also has It is beneficial to improve the conductivity of silicon materials. Patent CN 103579589A describes graphene-silicon-graphene to prepare layered negative electrodes. Although high performance can be obtained, the method is relatively complicated. The raw materials are gaseous carbon sources and silicon sources. The preparation cost is high, the safety is poor, and the equipment requirements are high, which is not conducive to the development of industrialization

And we use carbon nanotubes, graphene, silicon composite system will reduce the difficulty and cost of preparation, high safety, and can be prepared on a large scale; Electrode materials are prepared in this way, but due to their direct mixing, they are not well coated on the structure, resulting in poor cycle performance and low Coulombic efficiency.

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