Anomalous Shape Changes of Silicon Nanopillars by Electrochemical Lithiation

Seok Woo Lee, Matthew T. McDowell, Jang Wook Choi, Yi Cui

Research output: Contribution to journalArticlepeer-review

367 Scopus citations

Abstract

Silicon is one of the most attractive anode materials for use in Li-ion batteries due to its ∼10 times higher specific capacity than existing graphite anodes. However, up to 400% volume expansion during reaction with Li causes particle pulverization and fracture, which results in rapid capacity fading. Although Si nanomaterials have shown improvements in electrochemical performance, there is limited understanding of how volume expansion takes place. Here, we study the shape and volume changes of crystalline Si nanopillars with different orientations upon first lithiation and discover anomalous behavior. Upon lithiation, the initially circular cross sections of nanopillars with 〈100〉, 〈110〉, and 〈111〉 axial orientations expand into cross, ellipse, and hexagonal shapes, respectively. We explain this by identifying a high-speed lithium ion diffusion channel along the 〈110〉 direction, which causes preferential volume expansion along this direction. Surprisingly, the 〈111〉 and 〈100〉 nanopillars shrink in height after partial lithiation, while 〈110〉 nanopillars increase in height. The length contraction is suggested to be due to a collapse of the {111} planes early in the lithiation process. These results give new insight into the Si volume change process and could help in designing better battery anodes. © 2011 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)3034-3039
Number of pages6
JournalNano Letters
Volume11
Issue number7
DOIs
StatePublished - Jul 13 2011
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-11-001-12, KUK-F1-038-02
Acknowledgements: This work is partially supported by the Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under contract DE-AC02-76SF0051 through the SLAC National Accelerator Laboratory LDRD project. Y.C. acknowledges support from the King Abdullah University of Science and Technology (KAUST) Investigator Award (No. KUS-11-001-12). S.W.L. acknowledges support from KAUST (Award No. KUK-F1-038-02). M.T.M. acknowledges support from the Chevron Stanford Graduate Fellowship, the National Defense Science and Engineering Graduate Fellowship, and the National Science Foundation Graduate Fellowship. J.W. C. acknowledges the National Research Foundation of Korea Grant funded by the Korean Government (MEST) for the financial support through the Secondary Battery Program (NRF-2010-0029031) and the World Class University Program for the financial support (R-31-2008-000-10055-0).
This publication acknowledges KAUST support, but has no KAUST affiliated authors.

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