A Nanocomposite of Si@C Nanosphere and Hollow Porous Co9S8/C Polyhedron as High-Performance Anode for Lithium-Ion Battery

Silicon (Si) is regarded as one of the most promising anode materials for lithium-ion batteries (LIBs) due to its high capacity and low working voltage. However, dramatic volume expansion and inferior electrical conductivity greatly impede the commercial use of Si anodes. Herein, we design and synthesize a novel nanocomposite of Si nanosphere coated by carbon (Si@C) and hollow porous Co9S8/C polyhedron (Si@C-Co9S8/C). The hollow porous Co9S8/C derived from Co-based zeolitic imidazolate framework can serve as a buffering matrix to accommodate the volume expansion of Si, which is beneficial to improve the cycle performance. The vast conductive carbon layer originated from Co9S8/C and Si@C plays a key role in accelerating the electron transfer and lithium ion transport kinetics, which can significantly enhance the rate performance. As a result, the Si@C-Co9S8/C anodes deliver stable cycle performance with a reversible capacity of 1399 mA h g(-1) after 200 cycles at 100 mA g(-1), improved rate performance and high Coulombic efficiency. This simple route sheds light on designing Si-based composites for LIBs anodes.