A New Design Rule for Developing SiO with High Performance: Controlling Short‐Range Ordering of SiO2 Phase

Abstract Simultaneously achieving high initial coulombic efficiency (ICE) with high reversible capacity and excellent cycle retention is a key factor for developing next‐generation SiO anode, but it has never been achieved. Here, a new potential for achieving these desired properties simultaneously by controlling of short‐range ordering of amorphous SiO 2 matrix in SiO anode is reported. The controlled SiO has a unique microstructure that consists of a nano‐crystalline Si phase dispersed within SiO 2 matrix that is short‐range ordered while maintaining an amorphous state in the long‐range. It is found that a high degree of short‐range ordering in SiO 2 phase can change the pathway of the irreversible reactions of SiO anode forming less lithiated Li─Si─O phase, and this can result in high ICE (79.6%) with high reversible capacity after the first cycle (1582 mAh g −1 ) of SiO anode. Furthermore, even though the irreversible reactions can be significantly suppressed in the controlled SiO anode, the resulting material achieved excellent long‐term cycle stability (82.8% up to 100 cycles at 1 C rate). It is demonstrated that control of short‐range ordering of amorphous SiO 2 matrix in SiO while maintaining its long‐range disordering is a key design rule to simultaneously achieve both high ICE and high reversible capacity with long‐term cycle stability.