High throughput production of nanocomposite SiOx powders by plasma spray physical vapor deposition for negative electrode of lithium ion batteries

Abstract

Nanocomposite Si/SiOx powders were produced by plasma spray physical vapor deposition (PS-PVD) at a material throughput of 480 g h -1. The powders are fundamentally an aggregate of primary ∼20 nm particles, which are composed of a crystalline Si core and SiOx shell structure. This is made possible by complete evaporation of raw SiO powders and subsequent rapid condensation of high temperature SiOx vapors, followed by disproportionation reaction of nucleated SiOx nanoparticles. When CH4 was additionally introduced to the PS-PVD, the volume of the core Si increases while reducing potentially the SiO x shell thickness as a result of the enhanced SiO reduction, although an unfavorable SiC phase emerges when the C/Si molar ratio is greater than 1. As a result of the increased amount of Si active material and reduced source for irreversible capacity, half-cell batteries made of PS-PVD powders with C/Si=0.25 have exhibited improved initial efficiency and maintenance of capacity as high as 1000 mAh g-1 after 100 cycles at the same time. © 2014 National Institute for Materials Science.