Crystalline Evaluation of Size-Controlled Silicon and Silicon Oxide Nanoparticles Produced by Solution Plasma Discharge

Abstract

Li-ion batteries using Si particles as anode materials have attracted attention because of their extremely high theoretical capacities. However, they experience extensive volume expansion during lithiation in the process of charging, dramatically affecting the battery lifetime. To mitigate these expansion effects and improve the capacity, Si nanoparticles and occasionally SiO_x particles have been effective. Therefore, the production of Si nanoparticles is necessary. For these purposes, the solution plasma discharge method was applied. We improved previous work on the plasma discharge method by adjusting the electrolyte medium conditions via controlling the pH, solution conductivity, electrolyte concentration, and voltage, successfully generating Si nanoparticles with diameters of <10 nm and SiO_x particles of <50 nm in diameter. These crystalline Si and amorphous SiO_x particles were characterized using microscopy and spectroscopy.

SiO_x particles produced by plasma discharge method. (a) HAADF image, and (b) EELS data from boxed area in (a).