Understanding the Relationship Between Stress Change and Electrochemical Performance of a Heated SiO Anode Through In Situ Raman Spectrum

Silicon monoxide (SiO) has drawn researchers’ attention and been widely studied due to its high capacity and excellent cyclability. Compared with pure Si anode, SiO anode exhibits lower specific capacity but better cycling stability due to its unique microstructure formed by Si and O atoms. The disproportionation reaction of SiO can be caused by heating, which can change the distribution of Si and O atoms and is commonly used as pretreatment. The electrochemical properties of SiO with different disproportionation degrees vary a lot. However, the mechanism how disproportionation affects the electrochemical properties of SiO still remains unclear. Also, crystallization takes place during heat treatment at the same time. In this study, different disproportionated SiO materials were obtained by heating raw SiO at various temperatures. The stress change caused by crystallization could hinder the lithiation process of SiO particles, and it was measured by in situ and ex situ Raman spectroscopy to propose a new perspective to illustrate the impact of disproportionation on electrochemical properties. A crystallization phenomenon of Si domains in SiO materials caused by short-wavelength laser was firstly found through ex situ Raman spectroscopy tests.