Interfacial Electronic Coupling in Si@SiC@EG Core-Shell Architectures Enables High-Capacity and Long-Life Lithium-Ion Batteries.

Silicon anodes have attracted considerable attention as next-generation lithium-ion battery materials owing to their exceptionally high theoretical capacity. However, their practical application remains limited by severe volume fluctuations during cycling, which lead to rapid capacity fading. In this work, a Si@SiC@ epitaxial Graphene (EG) core-shell nanocomposite is constructed through in situ epitaxial growth to overcome these challenges. The SiC interlayer functions as a robust mechanical buffer, accommodating the volume expansion of silicon during lithiation and delithiation, while the external graphene shell offers high electronic conductivity, structural resilience, and may provide additional Li+ storage sites. Structural and electrochemical characterizations, including ex situ X-ray diffraction, in situ Raman spectroscopy, and ex situ X-ray photoelectron spectroscopy, verify the reversible Li+ insertion/extraction and the preservation of structural integrity without phase collapse. The Si@SiC@EG anode delivers a high reversible capacity of 1747 mAh g-1 at 0.1 A g-1, outstanding rate performance, and remarkable durability, maintaining 872 mAh g-1 after 2000 cycles at 1 A g-1. Density functional theory calculations further indicate that strong interfacial coupling effectively lowers Li+ migration barriers, thereby improving ion transport kinetics. These findings highlight the potential of the Si@SiC@EG heterostructure as a viable platform for high-energy-density lithium-ion storage.