Influencing Factors and Promotion Strategies of the First-cycle Coulombic Efficiency of Silicon Suboxide Anodes in Lithium-ion Batteries

The popularity of electric vehicles and various portable electronic devices has led to higher demands on battery energy density. Silicon suboxide (SiOx, 0<x <= 2) shows high specific capacity and low Li-ion insertion potential,and the volume expansion effect is significantly lower than that of pure silicon anode, and therefore is considered to be one of the ideal alternatives to traditional graphite anode materials. However, the solid electrolyte interphase (SEI) and a large number of irreversible products are formed during the first lithiation/delithiation cycle, resulting in low Coulombic efficiency,which seriously hinders the practical application of SiOx anodes. On the basis of SiOx structure,this review systematically explained the lithium storage mechanism of SiOx anode and the reason for the low first-cycle efficiency. Further, strategies of improving the first Coulombic efficiency of SiOx anode in recent years is summarized in detail. Finally, the future direction of improving the first-cycle efficiency of SiOx anode is also forecasted.