Silicon-based nanometer composite anode material for lithium ion battery and preparation method of silicon-based nanometer composite anode material

Abstract

The invention discloses a novel silicon-based nanometer composite material for a lithium ion battery anode and a preparation method of the novel silicon-based nanometer composite material, belonging to the field of electrochemical sources. The preparation method comprises the following steps: adding a small amount of graphite and ductile metal element tin, thereby preparing a silicon-based nanometer bicontinuous phase structure composite material by adopting a high energy ball milling method. Generally, the atomic percent of silicon in the selected alloying component is over 50 percent, properly 65-80 percent. The high energy ball milling is performed under argon atmosphere protection, and compounding between silicon and the ductile metal tin is realized by utilizing continuous cold welding and tearing under high-energy impact, so that the silicon and the metal element tin with high deformation capacity are interpenetrated, and an open three-dimensional mesh structure is formed in the space. The novel silicon-based nanometer bicontinuous phase structure composite material is simple in preparation process and low in cost and has excellent electrochemical performance and excellent application prospects.

Description

technical field [0001] The invention relates to the technical field of electrochemical power sources, in particular to silicon-based nanocomposite materials for lithium-ion batteries, in particular to a silicon-based nanocomposite negative electrode material for lithium-ion batteries and a preparation method thereof. Background technique [0002] Lithium-ion batteries are widely used as energy storage systems in aerospace, military, automobile industry, electronic equipment and biomedical fields due to their long service life, high output voltage, low self-discharge, and environmental friendliness. However, at present, most commercial lithium-ion batteries use carbon materials as negative electrodes, such as activated carbon and graphite. Due to the low specific capacity of these carbon materials, it is difficult to meet the requirements of high energy density. In order to further improve the performance of lithium-ion batteries and meet the needs of industrial development,...

AI Technical Summary

Problems solved by technology

However, in the common silicon-carbon composite materials, the deformation of carbon materials is only about 10%, which cannot accommodate large-scale volume changes of silicon particles. At the same time, due to the low theoretical specific capacity of carbon materials, its addition reduces The overall specific capacity of the negative electrode material

In addition, the bonding strength between silicon, carbon materials, and copper current collectors is low, and stable electrical contact cannot be formed during charging and discharging. Silicon is a semiconductor with low conductivity, which easily leads to the deposition of lithium ions on the negative electrode. Negative polarization, which reduces cycle life

In terms of preparation of composite anode materials, preparation methods such as electrochemical deposition and magnetron sputtering are complicated in process and high in cost, making it difficult to achieve large-scale industrial production.

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