Magnesium and magnesium-silicide coated silicon nanowire composite anodes for lithium-ion batteries

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DOIResolve DOI: http://doi.org/10.1039/c2ta00769j
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TypeArticle
Journal titleJournal of Materials Chemistry A
ISSN2050-7488
Volume1
Issue5
Pages16001612; # of pages: 13
SubjectCoulombic efficiency; Degradation mechanism; Electrical contacts; Electrochemical cycling stability; Electrolyte decomposition; Lithium-ion battery anodes; Magnesium silicides; Quantitative information; Anodes; Coated materials; Degradation; Lithium batteries; Magnesium; Polyethylene oxides; Silicides; Silicon; Transmission electron microscopy; Nanowires
AbstractWe synthesized composites consisting of silicon nanowires (SiNWs) coated with magnesium (Mg) and magnesium silicide (Mg2Si) for lithium-ion battery anodes and studied their electrochemical cycling stability and degradation mechanisms. Compared to bare SiNWs, both Mg- and Mg 2Si-coated materials show significant improvement in coulombic efficiency during cycling, with pure Mg coating being slightly superior by ∼1% in each cycle. XPS measurements on cycled nanowire forests gave quantitative information on the composition of the SEI layer and showed lower Li2CO3 and higher polyethylene oxide content for coated nanowires, thus revealing a passivating effect towards electrolyte decomposition. Extensive characterization of the microstructure before and after cycling was carried out by scanning- and transmission electron microscopy aided by focused ion beam cross-sectioning. The formation of large voids between the nanowire assembly and the substrate during cycling, causing the nanowires to lose electrical contact with the substrate, is identified as an important degradation mechanism. © 2013 The Royal Society of Chemistry.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); National Institute for Nanotechnology (NINT-INNT)
Peer reviewedYes
NPARC number21269786
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Record identifier3278cb69-eee9-4827-9356-239d17ca1aa2
Record created2013-12-13
Record modified2016-05-09
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