Prelithiated Surface Oxide Layer Enabled High-Performance Si Anode for Lithium Storage

SiO _x coating is an effective strategy to prolong the cycling stability of Si-based anodes due to the robust interaction between Si and the SiO _x layer. However, the SiO _x layer-protected Si anode is limited by the relatively low initial Coulombic efficiency and sluggish Li⁺ diffusion ability induced by the SiO _x layer. Herein, we present the preparation of selectively prelithiated Si@SiO _x (Si@Li₂SiO₃) anode by using a facile strategy to resolve the above issues. As the anode for lithium ion batteries, Si@Li₂SiO₃ exhibits a high initial Coulombic efficiency (ICE) of 89.1%, an excellent rate performance (959 mA h g^-1 at 30 A g^-1), and a superior capacity retention (3215 mA h g^-1). The full cell with LiFePO₄ cathode and Si@Li₂SiO₃ anodes is successfully assembled, disclosing a high ICE of 91.1% and excellent long cycling stability. The superior electrochemical performance of Si@Li₂SiO₃ can be attributed to the coating layer, which can strengthen the integrity of the electrode, decrease irreversible reactions, and provide efficient Li⁺ diffusion channels.