Research On Preparation Of Silicon Nanoparticles By Using Spark Discharge And High-energy Ball Milling Technologies

Silicon(Si)nanomaterials are widely employed in ceramic,optics,micro-electronics and other fields.Preparation methods of Si nanoparticles divide into chemical methods and physical methods.Chemical methods(such as CVD)have many shortcomings,such as harsh reaction conditions,complex process route,poor controllability and low yield.While physical methods(such as ball milling)can't meet the application requirements of high efficiency and low cost preparation.This paper,with semiconductor compound machining method,fabricated the micro-,submicro-Si particles from heavily doped boron mono-crystal silicon ingot by means of spark discharge method.The particle size can be further reduced to dozens of nanometers using high-energy ball milling,realized a “top-down” and high-efficient process route to produce Si nanostructures.This paper conducted related electrochemical property tests on this basis,and the specific process is as follows:1.Using heavily doped boron mono-crystal silicon ingot(0.01 ?·cm)as a workpiece and copper tube as a tool,spark discharge fabricated the micro-,submicro-Si particles,particle size(D50)of which is about 1.45?m.Then even-distributed nano-Si particles,particle size(D50)of which is approximately 88 nm,can be prepared by means of high-energy ball milling.2.To verify the weaken effects of nano-Si particles on the significant volume effect associated with lithiation/delithiation processes,this paper conducted related electrochemical property tests on micro-,submicro-Si and nano-Si particles,and the results as follows: The first time discharge specific capacity of the micro-,submicro-Si is extremely high,which is more than 4000 mAh/g.However,after 65 cycles,discharge capacity of the Si-based electrode maintains at about 300 mAh/g,which corresponds to ~8% capacity retention.As a contrast,the first time discharge specific capacity of the nano-Si is 2717.3 mAh/g.And after 65 cycles,discharge capacity of the Si-based electrode maintains at about 1458.6 mAh/g,which corresponds to ~66.84% capacity retention.