Metal-organic frameworks-derived CoMOF-D@Si@C core-shell structure for high-performance lithium-ion battery anode

Abstract

Silicon (Si) is considered as the most promising candidate for anode materials in the next-generation lithium-ion batteries (LIBs). Regulating the morphology and structure of Si plays a vital role in alleviating the volume expansion and improving electronic conductivity. Herein, an ingenious core-shell structure (denoted as CoMOF-D@Si@C) is synthesized by depositing Si uniformly on the pyrolytic metal-organic frameworks (MOFs) via chemical vapor deposition (CVD) method and then encapsulated with a carbon shell. The CoMOF-D@Si@C exhibits excellent rate capability and cycle performance, which delivers a high-rate capability of ~957 mAh g−1 at 10 A g−1 and a reversible capacity of 1493 mAh g−1 after 400 cycles. In particular, the capacity is maintained at 648 mAh g−1 after 1200 cycles at a high current density of 4 A g−1 with a rapid increase of the Coulombic efficiency (CE) to 99.8% after only 5 cycles and the average CE (99.7%) in the whole cycling at 4 A g−1. Profiting from the outer carbon shell, uniform Si deposition and inner porous pyrolytic MOF structure, this architecture can maintain structural stability and provide constructive conductivity during cycling processes. The superior electrochemical performance of the CoMOF-D@Si@C composite makes it a promising anode material for LIBs.