Preparation method of silicon alloy-graphene composite negative electrode material

Abstract

The invention relates to a preparation method of a silicon alloy-graphene composite negative electrode material. The preparation method comprises the following steps of: (1) putting Si, Co, Mn, Zn and Mg powder into a ball-milling tank according to proportions of the Si, Co, Mn, Zn and Mg powders needed for a Si2.05Co0.15Mn0.23Zn0.56Mg0.22 material, and carrying out ball-milling to obtain multielement alloy silicon; (2) preparing high-purity nanometer graphene by using graphite powder; and (3) mixing the silicon alloy and the high-purity nanometer graphene, and carrying out ball-milling to obtain the product. According to the silicon alloy-graphene composite negative electrode material prepared by the method for lithium-ion batteries, the silicon and the multiple metals are prepared into the multielement alloy silicon so as to increase the electric conductivity and cycling stability of the silicon alloy, then the multielement alloy silicon is composited with the high-purity nanometer graphene so as to achieve good cycling stability. When being used in the lithium-ion batteries, the composite material has high capacity and long service life.

Description

Technical field [0001] The invention relates to a preparation method of a silicon alloy-graphene composite negative electrode material. Background technique [0002] Energy is an important material basis for the development of human society, but the sharp decline in the stock of mineral energy such as coal, oil, and natural gas has caused human beings to face the pressure of resource depletion, and the problem of environmental pollution is also becoming more and more serious. Therefore, energy and environmental issues have become the focus of attention of countries all over the world. Improving energy efficiency, developing and utilizing renewable energy, protecting the ecological environment, and realizing sustainable development have become the common goals and topics of governments and researchers of all countries. Strategically speaking, the development of renewable energy is fundamental to solving energy problems, so research in this area has received widespread attent...

AI Technical Summary

Problems solved by technology

However, the low initial Coulombic efficiency and extremely poor cycle performance of silicon materials limit its practical application.

To sum up, there are three main reasons that prevent silicon-based materials from being used as anode materials for lithium-ion batteries: first, the serious volume effect of silicon in the process of charging and discharging cycles leads to the collapse of the material structure; The irreversible transformation from the crystalline state to the disordered state causes serious damage to the structure of the material; third, the poor electrical conductivity of silicon, and the uneven reaction with lithium reduces the cycle performance of silicon materials

In recent years, a large number of battery workers have carried out a lot of research on silicon-based materials. Silicon alloys have become a hot spot in the research of silicon powder-based composite materials because of their high volumetric energy density. However, these alloys have not fully utilized the properties of various metals. Synergistic effect, although the electrochemical performance of these alloy materials has been greatly improved compared with pure silicon, the improvement of cycle performance is still very limited