Silicon Nanoparticles Preparation by Induction Plasma Technology for Li-ion Batteries Anode Material

The monocrystalline silicon nanoparticles were prepared by induction plasma technology with micron silicon powder as raw material. The mean particle size is 70 and 15 nm silicon nanoparticles prepared with the quenching gas flow rate at 50 and 100 L min −1 , respectively. The particle size, crystallinity and morphology are mainly influenced by the quenching gas flow rate. The fine grit silicon nanoparticles can be formed under the condition of high quenching gas flow rate due to the inhibition of nucleation and growth. The silicon nanoparticles were used to synthesis Si@Graphite composites, the initial discharge capacity and coulombic efficiency of 70 nm Si@Graphite composites are 531.9 mAh g −1 and 83.4%, while 15 nm Si@Graphite composites are 510.6 mAh g −1 and 81.73%, respectively. The capacity retention of 70 nm Si@Graphite composites after 500 cycles is only 52.9%, while 15 nm Si@Graphite composites is 88%. It has been found the fracture of silicon nanoparticles and graphite along with the destruction of electrode structure lead to the capacity loss in the 70 nm Si@Graphite composites electrode. Because the forming of larger solid electrolyte interphase (SEI) film in 15 nm Si@Graphite composites electrode, the charge transfer on the electrode surface is hindered. However, the lithium-ion diffusion ability of 15 nm Si@Graphite composites is little higher than 70 nm Si@Graphite composites.