Core-shell structured heterohierachical porous Si@graphene microsphere for high-performance lithium-ion battery anodes

Abstract

Core-shell structured heterohierachical porous Si@graphene (HH-P-Si@G) composite with hierarchical porous silicon nano/microsphere as core material and highly conductive graphene as shell layer was designed and experimentally prepared by a selective acid etching strategy followed by a chemical vapor deposition (CVD) process. The synthesized HH-P-Si@G microsphere can deliver a high specific capacity of 2200 mAh g−1 at 0.2 A g−1 and 809 mAh g−1 at 3.2 A g−1, and can still deliver a high specific capacity of 1124 mAh g−1 after 120 cycles at 0.4 A g−1. The good electrochemical performance of HH-P-Si@G microsphere is closely related to the exterior graphene in improving the electrical conductivity of the composite and shielding the diffusion of electrolyte into interior silicon, as well as the hierarchical nano/micro structure in accommodating the volume changes of silicon during lithiation process.