Solution Synthesis Of Phosphorus/Silicon Anode Materials For Lithium Ion Batteries

At present,common anode materials in lithium-ion batteries include carbon anode materials,phosphorus-based anode materials,and silicon-based anode materials.The capacity of carbon materials is low while the theoretical specific capacities of phosphorus-based anode and silicon-based anodes are very high,but they also have problems such as poor conductivity,severe volume expansion,and poor cycle stability.In order to solve these problems,the main method is to use the carbon material to limit active materials,and leave sufficient free space to accommodate their expansion,so as to improve the cycle stability and conductivity of the material.In this paper,a simple solution method is designed,in which red phosphorus and chlorosilane are used as raw materials respectively to compound with carbon nanotubes.Then,polyphosphides and silicon dioxide are injected into the carbon nanotubes respectively by condensation and reflux.Phosphorus-based anode materials and silicon-based anode materials with high stability are synthesized.The main experimental content and results of this subject are as follows:1.The solution method is designed by which the red phosphorus is converted into polyphosphide and injected into the carbon nanotubes.Different kinds of carbon nanotubes are used to synthesize MWCNT/PP.It is found that the content of the polyphosphide will increase with the increase of the inner diameter of the carbon nanotubes.The maximum content is 32%.When the material is applied to the lithium-ion battery,the initial discharge capacity is up to 1386 m A h g^-1at a current density of0.1 A g^-1.After 100 cycles,the discharge specific capacity of the battery is 1012 m A h g^-1.Comparing the cell performance with GO/PP,the capacity of GO/PP decays very quickly,which shows the importance of the limitation of carbon nanotubes.This experiment effectively improves the stability and conductivity of the phosphorus-based anode material.2.MWCNT/SiO₂ is prepared by compounding carbon nanotubes with silicon tetrachloride by solution method,and the maximum silica content is 23%,which is applied to the negative electrode of lithium ion batteries.At a current density of 0.1 A g^-1,the initial discharge capacity reaches 600 m A h g-1,and the reversible discharge specific capacity is about 425 m A h g-1.What's more,there is no significant decay after2000 cycles,which indicates that the material is able to effectively limit the active material in the carbon nanotubes,and there is sufficient free space in the nanotubes to accommodate the volume expansion of silicon dioxide.In addition,carbon nanotubes also effectively improves the conductivity of the material.This experiment provides a new idea for the treatment of industrial chlorosilane waste.