Abstract
Monolithic carbon/nano-silicon composites with a three-dimensionally ordered macroporous (3DOM) structure were synthesized via a nanocasting route using a macro- and mesoporous silica monolith as a hard template for carbon with similar hierarchical porosity, followed by chemical vapor deposition to infiltrate mesopores with silicon nanoparticles. Diiodosilane was used as the silicon precursor to produce nano-silicon upon thermal decomposition. X-ray photoelectron spectroscopy revealed the presence of both elemental silicon and oxidized silicon in the porous carbon. Silicon was dispersed uniformly inside 3DOM carbon without forming large agglomerates. The as-synthesized material was X-ray amorphous. A lithiation experiment showed an initial charge capacity of 920 mAh g-1 and a reversible Li+ capacity of 332 mAh g-1 for the carbon/nano-silicon composite. The lower-than-expected capacity is attributed to partial oxidation of nanosized silicon in the composite structure. A mechanism for decomposition of diiodosilane in this system is proposed.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1702-1710 |
| Number of pages | 9 |
| Journal | Carbon |
| Volume | 46 |
| Issue number | 13 |
| DOIs | |
| State | Published - Nov 2008 |
Bibliographical note
Funding Information:This research was supported by the Office of Naval Research (Grant Number N00014-07-1-00608, subcontracted from NWU) and the Petroleum Research Foundation administered by the American Chemical Society (ACS-PRF Grant Number 42751-AC10). Parts of this work were carried out in the Institute of Technology Characterization Facility, University of Minnesota, which receives partial support from NSF through the NNIN program. The authors thank Professor W.H. Smyrl for use of the electrochemical equipment. ZW thanks the University of Minnesota Graduate School for a Doctoral Dissertation Fellowship.
