Preparation method of rate-type lithium ion battery silicon composite oxide material

Abstract

The invention discloses a preparation method of a rate-type lithium ion battery silicon composite oxide material, which comprises the following steps: (1) dispersion: preparing a carbon nanotube dispersion liquid from a surfactant and carbon nanotubes; (2) coating: adding tetraethoxysilane into the carbon nanotube dispersion liquid prepared in the step (1), stirring for reaction at room temperature, and drying to obtain a silicon dioxide coated carbon nanotube; (3) chemical deposition: preparing a carbon-coated silicon dioxide carbon nanotube from the silicon dioxide carbon nanotube obtained in the step (2) by adopting a chemical deposition method; and (4) gas-phase reaction: grinding the carbon-coated silicon dioxide carbon nanotube prepared in the step (3) and magnesium powder in proportion, heating, keeping constant temperature, cooling to room temperature, pickling, washing and drying to obtain the rate-type lithium ion battery silicon composite oxide material. The silicon composite oxide material prepared by the method has excellent rate capability and cycle performance, and the preparation process is simple and practical.

Description

technical field [0001] The invention belongs to the field of lithium-ion battery production, and in particular relates to a method for preparing a silicon composite oxide material for a rate-type lithium-ion battery. Background technique [0002] Compared with other types of secondary batteries, lithium-ion batteries have the advantages of higher energy density, longer cycle life, and smaller self-discharge. The field has a very wide range of applications; with the development of science and technology, electronic equipment has put forward higher requirements for battery energy density and power density. The traditional lithium-ion battery negative electrode material is mainly graphite, and its theoretical capacity is 372mAh / g. In practical applications The capacity of graphite can exceed 360mAh / g, which has basically reached the theoretical limit, and it is difficult to make a breakthrough from the perspective of technology. [0003] Compared with graphite materials, silic...

AI Technical Summary

Problems solved by technology

[0002] Compared with other types of secondary batteries, lithium-ion batteries have the advantages of higher energy density, longer cycle life, and smaller self-discharge. The field has a very wide range of applications; with the development of science and technology, electronic equipment has put forward higher requirements for battery energy density and power density. The traditional lithium-ion battery negative electrode material is mainly graphite, and its theoretical capacity is 372mAh / g. In practical applications The capacity of graphite can exceed 360mAh / g, which has basically reached the theoretical limit, and it is difficult to make a breakthrough from the perspective of technology

[0003] Compared with graphite materials, silicon is currently the material with the highest theoretical capacity among the anode materials of lithium-ion batteries. Silicon can form lithium-silicon alloy Li3.75Si with lithium ions, and the theoretical capacity is as high as 3752mAh / g, which is basically equivalent to ten times that of graphite materials. times, so the application of silicon materials can greatly increase the energy density of lithium-ion batteries; however, silicon materials face two problems in practical applications: one is that when lithium ions form lithium-silicon alloys with silicon, the volume will expand to the original 3 times, a huge internal stress is formed, which makes the silicon negative electrode detach from the current collector, causing the battery to fail; second, silicon is a semiconductor material with a much lower conductivity than graphite. Using silicon as the battery negative electrode material will cause battery internal The resistance is too large to charge and discharge with high current

[0004] In view of the above problems, the method of compounding silicon and carbon materials is currently used to alleviate the expansion of silicon, but the effect is limited. On the other hand, although the capacity of silicon oxide (SiOX) (about 1500mAh / g) is smaller than that of silicon There are many, but it is several times higher than the carbon-based negative electrode capacity (about 360mAh / g), and has a structure in which silicon nanocrystals are uniformly dispersed in a silicon dioxide matrix, which has gradually become a research hotspot

Images