A silicon-based negative electrode material with heterostructure, a preparation method thereof and a lithium ion battery are disclosed

Abstract

The invention provides a heterostructure silicon-based negative electrode material, a preparation method thereof and a lithium ion battery. The negative electrode material comprises carbon nanotubes,silicon distributed on the surface of the carbon nanotubes, and graphene coated on the silicon. 1) mixing that carbon nanotube and the acid, condensing and reflux, and then solid-liquid separation toobtain the carbon oxide nanotube; 2) after that carbon oxide nanotube is dispersed in wat, mixing with an organosilicon source, heating and reacting, and then solid-liquid separation; 3) mixing the product and the magnesium powder, crushing the mixture in an inert atmosphere, heating the mixture in an inert atmosphere, and heat treating the mixture; 4) under vacuum or inert atmosphere, taking carbon source as raw material to produce graphene by chemical vapor deposition on that product of the step 5) pickling to obtain the negative electrode material. The negative electrode material provided by the invention has good cycle stability and rate performance.

Description

technical field [0001] The invention belongs to the technical field of energy storage, and relates to a negative electrode material, in particular to a silicon-based negative electrode material with a heterogeneous structure, a preparation method thereof, and a lithium ion battery. Background technique [0002] With the wide application of consumer electronics and new energy vehicles, high specific energy lithium-ion batteries have become one of the research hotspots of researchers, and the capacity of materials directly affects the specific energy of batteries. At present, the theoretical gram capacity of commercial graphite-based negative electrode materials is only 372mAh / g, and its capacity has been developed and utilized to the limit. In comparison, the theoretical gram capacity of silicon materials is as high as 4200mAh / g (Li 4.4 Si). In addition, silicon also has a slightly higher lithium intercalation platform than graphite (0.2Vvs.Li + / Li), higher safety performa...

AI Technical Summary

Problems solved by technology

[0003] Although the silicon material has such great advantages, it has great defects in practical applications: (1) During the charging and discharging cycle of the silicon material, due to the large volume expansion (~300%), it is easy to cause the active material to break into powder; In addition, the expansion and contraction of silicon particles lead to the continuous rupture and formation of the surface SEI (Solid electrolyte interphase, solid electrolyte interface) film, which consumes the limited electrolyte and lithium in the positive electrode, causing the SEI film to thicken and the internal resistance of the battery to increase. Resulting in poor battery cycle performance; (2) As a semiconductor, silicon has much poorer conductivity than graphite, and the polarization is larger during charge and discharge, and the kinetic process is slower

[0008] However, the above-mentioned schemes all have the problem of cumbersome preparation methods and are not conducive to industrial production. Therefore, there is an urgent need in this field to develop an efficient preparation method that is simple, easy to achieve large-scale production, and has good product rate performance and cycle performance.