Microstructure and Electrochemical Performance of Li2CO3-Modified Submicron SiO as an Anode for Lithium-Ion Batteries

Silicon monoxide (SiO) holds great potential as a next-generation anode material for commercial lithium-ion batteries due to its high theoretical specific capacity. However, poor cycling stability and low initial Coulombic efficiency (ICE) present substantial challenges for its practical application. Herein, we modified the structure of commercial SiO through ball milling, followed by heating with the addition of the network modifier Li2CO3. The submicrometer-sized SiO reduces Li+ diffusion pathways within the SiO bulk, facilitating the Li+ insertion/extraction process and enabling excellent rate performance. Controlling the size of silicon nanodomains within SiO enhances the structural stability of the material during cycling, thereby significantly improving its cycling stability. The increased crystallinity of SiO2 suppresses irreversible reactions, leading to a higher ICE. Moreover, Li+ ions trapped within the Si-O-Si network form a lithium silicate glass-like phase, which provides efficient pathways for Li+ diffusion within the material, thereby enhancing its electrochemical performance. The optimized submicrometer SiO was mixed with graphite and coated with carbon to produce a submicrometer SiO/graphite@carbon composite anode. When assembled into a half-cell, the composite anode exhibited an initial discharge specific capacity of 1277.0 mA h g-1 at 0.1 A g-1, with an ICE of 74.3%. And this anode demonstrated a capacity retention of 79.7% after 300 cycles at 0.5 A g-1. Furthermore, during rate capability testing, it achieved a discharge specific capacity of 428.9 mA h g-1 at 1.6 A g-1.