Formation of Si nanoparticles by pulsed discharge of Si strips in distilled water

Abstract

Si nanoparticle features multiple excellent properties, such as high theoretical capacity of 4200 mAh/g and low volume expansion effect, and it is regarded as an outstanding anode electrode material for Li-ion batteries. In this study, we obtained Si nanoparticles through pulsed discharge of Si strips and analyzed the pulsed discharge process based on recorded current data. The recovered samples were characterized by various techniques, such as XRD, Raman spectroscopy, SEM, and TEM. The characterization results confirm that the recovered samples are smooth spherical Si nanoparticles smaller than 200 nm. Our investigation reveals that the charging voltage is a key factor to adjust the size distribution of recovered Si nanoparticles. In the charging voltage range of 4–7 kV, the increase of charging voltage value decreases D90 (the particle size at the 90% undersize point in the size distribution) of recovered Si nanoparticles from 48.7 to 24.9 nm. In the charging voltage range of 7–12 kV, the increase of charging voltage value increases D90 of recovered Si nanoparticles from 24.9 to 66.5 nm. Thus, the critical charging voltage value is 7 kV, at which condition D90 of formed Si nanoparticles is the minimum (24.9 nm). In addition, the analysis of discharge current curves indicates three discharge stages, including semiconductor joule heating, conductor joule heating, and plasma discharge, which possess correlation to the size distribution of formed Si nanoparticles.