Ball Milling Synthesis of Silicon Monoxide Anode Materials for Li-Ion Batteries

Abstract

Li-ion batteries are currently key energy storage devices for various applications such as mobile electronics, electric vehicles, and large-scale energy storage systems. Recently, the global demand for such applications is greatly increasing and in the meantime, high-energy density batteries should be developed to meet the demand. To increase the energy density, the development of high-capacity electrode materials is essential. Currently, graphite is commercially used as anode materials for Li-ion batteries and however, its capacity is limited (theoretical capacity: 372 mAh g­–1). As alternative anode materials, Li-alloy type materials have been intensively investigated to increase the capacity. Among them, Si is one of the most attractive materials because of the high theoretical capacity of 3580 mAh g–1 for Li15Si4 phase. However, it suffers from mechanical degradation caused by large volume change during Li insertion and extraction processes. Recently, silicon monoxide (SiO) materials have attracted great attention due to relatively better cycling stability, which is attributed to the role of oxygen. SiO usually exists in an amorphous form where the oxidation number of Si ranges from 0 to 4. This material can be synthesized by vaporization processes, which is possibly expensive. In this work, SiO materials were prepared by a simple mechanical ball milling process. To improve the electrochemical properties as anodes for Li-ion batteries, carbon incorporation was also performed. The carbon-incorporated SiO materials exhibit the enhanced electrochemical properties.