Synthesis of SiOx Nano-Powders Using a Microwave Plasma Torch at Atmospheric Pressure

Abstract

The silicon oxide nano-powders (SiO x -NPs) were obtained in an atmospheric microwave plasma torch using a gas-phase silicon tetrachloride (SiCl 4 ) with N 2 and H 2 . The gas-phase SiCl 4 was injected with H 2 gas into the microwave plasma torch generated by N 2 and air swirl gas, and then the dark brown powders were deposited on the inner wall of a quartz tube. The sample was analyzed by an X-ray photoelectron spectroscopy (XPS), a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS), and an X-ray diffraction (XRD). The average size and oxidation x values of synthesized SiO x -NPs were approximately 230 nm and 0.91, respectively. Furthermore, the volumetric charge capacity is 1127 mAh/g and has 89.2% retention after 100 cycles.

Oxygen Content-Controllable Synthesis of Non-Stoichiometric Silicon Suboxide Nanoparticles by Electrochemical Anodization

“…Nanoparticles are highly valuable for an extensive range of applications due to their high specific surface area. Silicon suboxide nanoparticles (SiO x NPs, 0 < x < 1), in particular, exhibit unique electrical, optical, chemical, and mechanical properties, allowing the particles to be actively used as semiconductors and a coating material [1][2][3]. The properties of SiO x NPs are heavily dependent on the oxidation state of the Si [4][5][6], which determines the oxygen content of the NPs.…”

“…SiO x NPs are being studied largely for their application as the anode material in lithium-ion batteries to potentially meet the high demand for batteries with higher capacity and longer service life [1,4,[7][8][9]. Currently, the batteries are reported to have a high charge capacity [2,[10][11][12] and a low volume expansion ratio [8,13]. Lithium oxides (e.g., Li 2 O and Li 4 SiO 4 ), produced by Li ion insertion into SiO x during initial charging, serve to buffer volume changes, improving charge cycle performance [14,15].…”

“…Si is not very reactive at low temperatures; therefore, conventional SiO x NPs synthesis procedures involve high-temperature reactions. The high-temperature reactions can be classified into two categories: melting-condensation [9] and chemical vapor deposition [1,2,4]. In the former, Si (or Si mixed with silica) is melted and oxygen is injected.…”