Optimizing Stable Initial Coulombic Efficiency of SiO/C enabled by using All in one process

Abstract

Silicon monoxide (SiO) for anode materials is attracted attention as a next substitute for replacing graphite-based anode materials because it has a much higher capacity than graphite and a better capacity retention than Si. However, SiO can also accommodate large volume expansion and large 1st cycle irreversible capacity lead to poor initial coulombic efficiency (ICE). By adding a small amount of Li sources (LiOH·H2O) and reacting at a lower temperature (900℃), amorphous SiO2 in SiO are converted into Crystallization SiO2 (c-SiO) which is lead to reduce the irreversible electrochemical reaction of SiO and enhance the ICE up to ~82.7%. Due to the remaining problems of SiO, recently many researchers mix SiO and graphite with proper proportional for improving the conductivity, cycling ability of SiO and alleviating the overall volume change. We study to compare the electrochemical properties of SiO/C composites depending on whether mixing pre-thermal-treated c-SiO and Graphite separately (Separation) or thermal-treated at once (All in one). All in one SiO/C has stable electrochemical properties than Separation, such as better ICE & Capacity with less amount of Li sources. The understanding and findings will pave the way to design high-capacity SiO/C with high ICE and long cycling ability for practical high energy density Li batteries.