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

Graphical Grind and coat : A novel nanocomposite of amorphous carbon-coated Si nanosphere and ZIF-67 derived hollow porous cobalt sulfide/carbon polyhedron is fabricated by a simple grinding process. ZIF-67 derived Co 9 S 8 /C can serve as a buffer to alleviate the volume expansion of Si. The vast conductive carbon layer originated from Co 9 S 8 /C and Si@C plays a key role in facilitating the electron transfer and lithium ion transport kinetics. Si@C−Co 9 S 8 /C anodes deliver improved electrochemical performance. 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 Co 9 S 8 /C polyhedron (Si@C−Co 9 S 8 /C). The hollow porous Co 9 S 8 /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 Co 9 S 8 /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−Co 9 S 8 /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.