Process for producing silicon-based carbon composite material for lithium ion battery cathode

Abstract

Disclosed is a process for producing a silicon-based composite material for a lithium ion battery cathode. The process comprises that silicon powder serves as a main material, graphite powder or flocculent carbon black serves as an auxiliary material, the main material and the auxiliary material are mixed and placed in a ball-grinding steel tank, argon serves as a shielding gas, the ball-grinding steel tank inflated with the shielding gas is placed in a planetary ball mill, and powder with granularity of less than 20 mum, which is the silicon-based composite material for the lithium ion battery cathode, is obtained after the mixture is subjected to ball milling at 500 revolutions / minute for 80 hours. The process has the advantages that the silicon material having the good lithium-storing capacity is mixed with the carbon material having the good electrical conductivity, atomic-grade mixing of the silicon material and the carbon material is achieved in a mechanical alloying mode, the electrical conductively of the silicon matrix is fully improved, and the inert carbon material can reduce volume expansion caused by the processes of lithium intercalation and lithium deintercalation of the silicon material in the processes of charging and discharging of the inert carbon material, so that the cycle performance of the silicon material is improved, the electrical conductivity and the cycle performance of the carbon-doped material are better than those of the pure silicon material.

Description

technical field [0001] The invention relates to a preparation technology of lithium-ion battery negative electrode materials, in particular to a preparation method of a lithium-ion battery negative electrode silicon-based carbon composite material. Background technique [0002] Lithium-ion batteries are a new generation of secondary batteries after lead-acid batteries, nickel-cadmium batteries and nickel-metal hydride batteries. Today, when the world is facing continuous shortage of oil resources and deteriorating environment, lithium-ion batteries have become a high-tech development due to their advantages such as high capacity, long cycle life, small self-discharge, no memory effect, no environmental pollution and good safety performance. One of the key points, it is considered to be an ideal choice for high-capacity, high-power batteries, and is an environmentally friendly power source in the 21st century. Since the commercialization of rechargeable lithium-ion batteries...

AI Technical Summary

Problems solved by technology

At present, the negative electrode materials of commercial lithium-ion batteries are mainly graphite materials. Graphite has a layered structure, and its volume expansion is small during charging and discharging, and it is not easy to pulverize the material. However, the theoretical processing capacity of graphite is small, only 400mAh / g

Silicon has attracted widespread attention due to its maximum theoretical processing capacity of 4200mAh / g. However, due to its close-packed structure, silicon has a large volume expansion and serious material pulverization during charge and discharge. In addition, the production cost of nano-silicon and thin-film silicon is high. Restricting its application in lithium-ion batteries

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