Edited by Stephen J. Harris, General Motors, Warren, MI, and accepted by the Editorial Board June 7, 2013 (received for review March 15, 2013)
The rice husk is the outer covering of a rice kernel and protects the inner ingredients from external attack by insects and bacteria. To perform this function while ventilating air and moisture, rice plants have developed unique nanoporous silica layers in their husks through years of natural evolution. Despite the massive amount of annual production near 108 tons worldwide, so far rice husks have been recycled only for low-value agricultural items. In an effort to recycle rice husks for high-value applications, we convert the silica to silicon and use it for high-capacity lithium battery anodes. Taking advantage of the interconnected nanoporous structure naturally existing in rice husks, the converted silicon exhibits excellent electrochemical performance as a lithium battery anode, suggesting that rice husks can be a massive resource for use in high-capacity lithium battery negative electrodes.
↵1D.S.J. and M.-H.R. contributed equally to this work.
Author contributions: D.S.J., S.B.P., and J.W.C. designed research; D.S.J. and M.-H.R. performed research; D.S.J., M.-H.R., and Y.J.S. analyzed data; and D.S.J., M.-H.R., and J.W.C. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission. S.J.H. is a guest editor invited by the Editorial Board.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1305025110/-/DCSupplemental.
