Preparation And Electrochemical Properties Of Silicon-based Anode Materials For Lithium Ion Batteries

With the development of mobile devices and electric vehicles,higher requirements are placed on the capacity and power of lithium-ion batteries.Silicon has a high theoretical specific capacity,making it an ideal material for increasing the capacity of lithium-ion batteries.However,when the silicon expands and discharges,the volume expands and is easily broken,which causes the electrochemical performance of the material to decrease.The paper uses coated and embedded type to prepare silicon-based/carbon composite materials to improve the electrochemical properties of the materials.The specific research contents are as follows:?1?Study on Direct Coating of Carbon on the Surface of Nano-Si Particles.The paper studied the process of preparing silicon/carbon composites by using glucose and dopamine as carbon sources by hydrothermal method and stirring method.The experimental results show that the capacity retention rate of the material after dopamine coating is 83.8%.Directly coated composites have agglomeration,resulting in a decrease in capacity.?2?Study on further coating of carbon after nano-silicon surface coated with nano-iron oxide.The paper prepared a nano-iron oxide coating on the surface of nano-silicon by chemical method,and then coated the carbon on the surface of nano-silicon/iron oxide by hydrothermal method and stirring method.The results show that the nanosilicon/iron oxide/ carbon composite particles prepared by dopamine coating have the smallest particle size.The initial discharge specific capacity was 663 mAh g^-1 at 100 m A g^-1 current density,and the capacity was stable at 388 mAh g^-1 after 100 cycles.?3?Preparation of nanosilicon/carbon composites with hollow structure by removing iron oxide from nanosilicon/iron oxide/carbon composite by nitric acid immersion.The capacity is stable at 239 mAh g^-1 after 100 cycles.?4?Uniform distribution of nano-iron oxide particles prepared on the surface of multilayer graphene by stirring in a water bath.Preparation of multilayer graphene/carbon nanotube composites using nanometer iron oxide/multilayer graphene composites as catalyst,embedding nano-silicon into a multilayer graphene/carbon nanotube composite having a porous structure by mixing grinding,the effect of the ratio of silicon to carbon on electrochemical performance was investigated.The results show that the material properties are best when the mass ratio of nano-silicon and multi-layer graphene/carbon nanotubes is 1:2,the initial discharge specific capacity at a current density of 100 mAg^-1 was 892 mAh g^-1,and after 100 cycles,the capacity was stable at 411 mAh g^-1.