Superior Lithium-ion storage properties of Si-based composite powders with unique Si@carbon@void@graphene configuration

Seung Ho Choi, Dae Soo Jung, Jang Wook Choi, Yun Chan Kang

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Composite powders of the configuration Si@carbon@ void@graphene were prepared by a one-step spray pyrolysis process, by adding polyvinylpyrrolidone (PVP) to a precursor solution containing graphene oxide (GO) sheets and silicon nanoparticles (NPs). Morphological analysis indicates that the individual Si NPs are coated with amorphous carbon and encapsulated in a micrometer-sized graphene ball structure that offers a large amount of buffer space. The addition of PVP improves the stability of the colloidal spray solution containing the GO sheets and the Si NPs. Consequently, the prepared Si@C@void@graphene composite powders have a relatively more uniform morphology than the Si@void@graphene composite powders prepared from the spray solution without PVP. The first charge and discharge capacities of the Si@C@void@graphene electrode measured at 0.1 Ag-1are as high as 3102 and 2215 mAhg-1, respectively. With an increase in the current rate from 0.5 to 11 Ag-1, 46% of the original capacity (i.e., 2134 mAhg-1) is maintained. After 500 cycles at a high rate of 7 Ag-1, the Si@C@void@graphene electrode shows 84% capacity retention and 99.8% of the average Coulombic efficiency. The superior cycling and rate capabilities of the prepared Si@C@void@graphene electrode could be attributed to the uniform carbon coating of the Si NPs and the graphene ball structure, which facilitates efficient diffusion of Li ions and prevents the penetration of electrolyte into graphene ball during cycling.

Original languageEnglish
Pages (from-to)2076-2082
Number of pages7
JournalChemistry - A European Journal
Volume21
Issue number5
DOIs
Publication statusPublished - 2015 Jan 26

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Keywords

  • Batteries
  • Energy efficiency
  • Graphene
  • Nanoparticles
  • Spray pyrolysis

ASJC Scopus subject areas

  • Chemistry(all)

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