Multielement silicon alloy/carbon composite material and preparation method and application thereof

Abstract

The invention relates to a multielement silicon alloy / carbon composite material and a preparation method and an application thereof, belonging to the field of the preparation of the lithium ion battery. The technical problem to be solved is to provide an anode material with large reversible capacity and good cycle performance of the lithium ion battery. The chemical composition of the multielement silicon alloy composite material is SixCoyMmNn / C, wherein M is at least one of B, Ti, Fe, Mn, Ni, Cu and Cr, N is at least one of In, Zn, Al and Mg; x, y, m and n separately represent atomic ratio, wherein 0.2<=x<=5.0, 0.1<=y<=2.0, 0.1<=m<=2.0 and 0.01<=n<=1.0. The multielement silicon alloy / carbon composite material of the invention can be used as the anode material of the lithium battery and is characterized by large specific capacity, long cycle life and stable performance.

Description

technical field [0001] The invention relates to a multi-element silicon alloy negative electrode material of a lithium ion battery and a preparation method thereof, belonging to the field of lithium ion batteries. Background technique [0002] Compared with traditional secondary batteries, lithium-ion batteries have the advantages of high open circuit voltage, high energy density, long service life, no memory effect, no pollution, and small self-discharge, and are more and more widely used. The current commercial lithium-ion battery anode material is a carbon-based anode material, but its theoretical capacity is only 372mAh / g, and it has been developed close to the theoretical value. Extensive demand for high-capacity high-power chemical power supplies. Therefore, a lot of research has turned to finding new anode material systems that can replace carbon materials, among which silicon is an ideal candidate material because it not only has a high lithium storage capacity, but...

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 due to their high volumetric energy density. At present, Ni-Si, Mn-Si, Cu-Si , FeSi, Si-Mn-Al, Si-Fe-Cu, Si-Co alloys have been studied, however, because these alloys have not fully utilized the synergistic effect of multiple metals, although these alloy materials are relatively electrochemical compared to pure silicon The performance has been greatly improved, but the improvement of cycle performance is still very limited, most of which are less than fifty cycles, which is still far away from practical application

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