Graphene-coated silicon nanoparticle with novel structure, and preparation method thereof

Abstract

The invention relates to the field of lithium ion battery electrode materials, in particular to a graphene-coated silicon nanoparticle with a novel structure, and a preparation method thereof. The graphene-coated silicon nanoparticle is characterized by being formed by a reduced graphene oxide / carbon shell coating an outer layer, a silicon nanoparticle core located in the reduced graphene oxide / carbon shell, and a cavity layer between the reduced graphene oxide / carbon shell and the silicon nanoparticle core. Compared with the prior art, according to the graphene-coated silicon nanoparticle provided by the invention, the thickness of a surface oxidation layer of a silicon particle is easy to control; surface oxidation silicon powder is dispersed in a solvent easily, and hydroxy on the surface of the particle enables the particle to be combined with a modifier easily; graphene coating the particle surface helps increase electric contact between particles as well as between the particle and a current collector, and is beneficial for electron transfer in a composite material to reduce impedance; carbon produced through high-temperature pyrolyzing of a modifier carbon chain and graphene jointly form a shell with a certain strength, and a stable SEI can be formed favorably.

Description

technical field [0001] The invention relates to the field of lithium-ion battery electrode materials, in particular to a novel structure graphene-coated silicon nanoparticle and a preparation method thereof. Background technique [0002] With the development of portable mobile devices and electric vehicles, people's demand for energy storage devices with higher energy density and higher power density is becoming more and more urgent. Lithium-ion batteries (372mAh / g) with graphite as the negative electrode can no longer meet consumer demand. , therefore, it is imminent to find anode materials with higher capacity. Because of its ultra-high theoretical lithium storage capacity (4200mAh / g) and abundant resources, silicon materials are considered to have the most potential to become the anode material of a new generation of lithium-ion batteries. However, silicon materials still have the following problems in the application of anode materials. Problems to be solved urgently: 1...

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Problems solved by technology

[0002] With the development of portable mobile devices and electric vehicles, people's demand for energy storage devices with higher energy density and higher power density is becoming more and more urgent. Lithium-ion batteries (372mAh / g) with graphite as the negative electrode can no longer meet consumer demand. , therefore, it is imminent to find anode materials with higher capacity

Because of its ultra-high theoretical lithium storage capacity (4200mAh / g) and abundant resources, silicon materials are considered to have the most potential to become the anode material of a new generation of lithium-ion batteries. However, silicon materials still have the following problems in the application of anode materials. Problems to be solved urgently: 1. As a semiconductor material, silicon has poor conductivity and slow electron migration rate. When it is used as the negative electrode material of lithium-ion batteries, the rate performance will inevitably be reduced; 2. During the charging and discharging process, due to the intercalation of lithium ions / de-intercalation, resulting in a change in the volume of the silicon material (volume expansion rate of more than 300%). This repeated volume change will inevitably lead to the collapse of the internal structure of the active material particles, reduce the contact between the active material particles, and cause the active material particles and the current collector. Detachment will eventually cause a series of problems such as capacity fading, rate performance reduction, and safety; 3. Unstable active material particle surface causes excessive formation of SEI, resulting in irreversible capacity loss

The composite material has high capacity and good cycle performance, but the preparation conditions are not easy to control, high energy consumption, difficult to batch production, and the resulting waste liquid containing Cu ions pollutes the environment

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