Preparation And Research Of Anode Materials For Lithium Ion Batteries Based On Porous Silicon

At present,lithium-ion battery rapidly occupies portable electronic devices with its irreplaceable advantages in performance and environmental.And the energy density continues to improve,has completed the short-term goal of 300 Wh/Kg proposed by the country.At present,graphite is still the mainstream anode material on the market,but the lower specific capacity of graphite has been unable to meet the demand.Si-based materials have obvious advantages in energy density and reserves,and provides an outstanding direction for high-capacity anode materials.But the large volume changes and low electrical conductivity limits its practical application.So far up till now,introducing reserved space and conductive species into silicon-based materials to manufacture novel style silicon anode has been considered the effective strategies to satisfy the demands of the emerging portable electronics.The introduced reserved space can buffer the huge changes in volume of Si during cycling,leading to the enhanced structural integrity and cycling stability.In this paper,the composites of silicon and carbon are studied in the following aspects:(1)The silicon nanoparticles(SiNPs)were modified with 3-aminopro-pyltrimethoxysilane(APTES)to positively charge the surfaces.Then,SiNPs were successively double coated with rigid phenolic resin and silica layers(Si@RF@Si O₂).Finally,carbon nanotubes(CNTs)were in-situ grown on the precursor microspheres via a CVD method.The outer CNTs networks can absorb the large volume expansion of SiNPs and shorten the ion diffusion pathways.This Si/CNTs composite demonstrated excellent cycling stability and rate performance with 912 m Ah g^-1 after 100 cycles at 0.1 A g^-1,and650 m Ah g^-1 at 1 A g^-1 after 1000 cycles.(2)SiNPs were doped into the carbon fiber network by electrospinning process to obtain three-dimensional interlinked Si/carbon nanofiber composite(Si/CNFs),which can directly be used as electrodes.This Si/CNFs composite demonstrated enhanced cycling and rate performance with 718.7 m Ah g^-1 after 100 cycles at 0.1 A g^-1.The three-dimensional interconnected carbon nanofiber network not only can effectively buffer the volume change of SiNPs and improve the overall electrical conductivity,but also act as collector,avoiding the use of binders and conductive additives.