Details

Autor(en) / Beteiligte

• Ashuri, Maziar
• He, Qianran
• Zhang, Kan
• Emani, Satyanarayana
• Shaw, Leon L.

Titel

Synthesis of hollow silicon nanospheres encapsulated with a carbon shell through sol–gel coating of polystyrene nanoparticles

Ist Teil von

• Journal of sol-gel science and technology, 2017-04, Vol.82 (1), p.201-213

Ort / Verlag

New York: Springer US

Erscheinungsjahr

2017

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• In this study a templating method to form hollow Si nanospheres encapsulated with a carbon shell (HSi@C) has been investigated. The key synthesis parameters and their optimization are studied. The positively charged surface of sacrificial polystyrene (PS) nanospheres is found to be essential in forming a uniform SiO 2 shell on PS through sol–gel reactions of tetraethylorthosilicate in a basic medium. Both the sol–gel reaction time and hydrolysis ratio play an important role in controlling the thickness of the SiO 2 shell. The PS core is burnt via a step-wise programmed heating to prevent the formation of cracks in hollow SiO 2 nanospheres which are subsequently converted to hollow Si nanospheres through magnesiothermic reduction using MgH 2 . Removal of the byproducts from the reduction is critical for superior electrochemical performance. The hollow Si nanospheres are coated with a carbon shell to form HSi@C which are evaluated as the active material for Li-ion battery anodes. Electrochemical results indicate significant improvements in the specific capacity and cycling stability of half-cells in comparison to other designs. The improvement is attributed to the synergistic effects of the engineered void and conductive carbon shell in HSi@C. Graphical Abstract Specific capacity and Coulombic efficiency of HSi@C half cells vs. cycle number at different current densities.