The effect of metallic coatings and crystallinity on the volume expansion of silicon during electrochemical lithiation/delithiation

Matthew T. McDowell, Seok Woo Lee, Chongmin Wang, Yi Cui

Research output: Contribution to journalArticlepeer-review

119 Scopus citations

Abstract

Applying surface coatings to alloying anodes for Li-ion batteries can improve rate capability and cycle life, but it is unclear how this second phase affects mechanical deformation during electrochemical reaction. Here, in-situ transmission electron microscopy is employed to investigate the electrochemical lithiation and delithiation of silicon nanowires (NWs) with copper coatings. When copper is coated on only one sidewall, the NW bilayer structure bends during delithiation due to length changes in the silicon. Tensile hoop stress causes conformal copper coatings to fracture during lithiation without undergoing bending deformation. In addition, in-situ and ex-situ observations indicate that a copper coating plays a role in suppressing volume expansion during lithiation. Finally, the deformation characteristics and dimensional changes of amorphous, polycrystalline, and single-crystalline silicon are compared and related to observed electrochemical behavior. This study reveals important aspects of the deformation process of silicon anodes, and the results suggest that metallic coatings can be used to improve rate behavior and to manage or direct volume expansion in optimized silicon anode frameworks. © 2012 Elsevier Ltd.
Original languageEnglish (US)
Pages (from-to)401-410
Number of pages10
JournalNano Energy
Volume1
Issue number3
DOIs
StatePublished - May 2012
Externally publishedYes

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