Stabilizing Bulk‐Phase and Accelerating Lithium Transport of Silicon Anode by Integrating Dual‐Encapsulation Architecture and Metal Composite Engineering

ABSTRACT The structural stability of silicon materials during cycling is ensured by a multilevel structural design, which is crucial for developing high‐energy‐density lithium‐ion battery anodes. In this study, a novel silicon composite (Si@SiO x @Cu 3 Si/NC) with a bilayer of silicon suboxide and N‐doped carbon embedded with Cu 3 Si alloy nanocrystals was designed by a nanoscale structural assembly method. The SiO x thin layer contributes to the effective stress release and uniform distribution, and inhibits the agglomeration of silicon nanoparticles, thus ensuring the mechanical stability and structural integrity of the composite. The in situ formation of Cu 3 Si establishes a connection between the silicon core and the carbon shell, providing an efficient electron transport path. The dual‐encapsulation architecture of silicon anode enhances the interface stability, forming a robust and rich‐LiF SEI film, which endows the material with high electrochemical reactivity and mechanical strength. The developed Si@SiO x @Cu 3 Si/NC displays a high reversible capacity (1752 mAh g −1 after 150 cycles at 0.1 A g −1 ), excellent cycling stability (864.1 mAh g −1 after 450 cycles at 1 A g −1 ) and rate performance (1052.3 mAh g −1 under 2 A g −1 ). This research provides a way to enhance the interface stability and transport kinetics of silicon‐based anodes through multifunctional coating design.