Bowl-like 3C-SiC Nanoshells Encapsulated in Hollow Graphitic Carbon Spheres for High-Rate Lithium-Ion Batteries

Searching for new electrode materials with high capacities and excellent rate performance is crucial for the development of next-generation lithium-ion batteries (LIBs). Silicon carbide (SiC), which is traditionally considered to be electrochemically inert toward lithiation, has recently been demonstrated to be a potential high-performance anode material upon activation by surface graphitization. Despite the great potential, it remains a grand challenge to synthesize SiC nanostructures with precisely controlled morphologies and surface properties, due to the rather high reaction temperatures (>1200 degrees C) typically required for SiC crystallization. Herein, we designed and synthesized a novel type of SiC nanostructures in which bowl-like, ultrathin SiC nanoshells were encapsulated in hollow graphitic carbon spheres (designated as SiC@HGSs), which exhibited unexpectedly high electrochemical performance when used as LIB anodes. SiC@HGSs retained a stable capacity of 1345 mAh g(-1) at a current density of 0.6 A g(-1) after 600 cycles and 742 mAh g(-1) at 3 A g(-1) after 1000 cycles. Even at a high current density of 6 A g(-1), SiC@HGSs could still deliver a capacity of similar to 400 mAh g(-1). The superior high-rate performance is attributable to the unique architecture and exceptional structural durability of SiC@HGSs.