Nanostructured Si(1- x)Gex for tunable thin film lithium-ion battery anodes

Paul R. Abel, Aaron Michael Chockla, Yong Mao Lin, Vincent C. Holmberg, Justin T. Harris, Brian A. Korgel, Adam Heller, C. Buddie Mullins*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

115 Scopus citations

Abstract

Both silicon and germanium are leading candidates to replace the carbon anode of lithium ions batteries. Silicon is attractive because of its high lithium storage capacity while germanium, a superior electronic and ionic conductor, can support much higher charge/discharge rates. Here we investigate the electronic, electrochemical and optical properties of Si (1-x)Gex thin films with x = 0, 0.25, 0.5, 0.75, and 1. Glancing angle deposition provided amorphous films of reproducible nanostructure and porosity. The film's composition and physical properties were investigated by X-ray photoelectron spectroscopy, four-point probe conductivity, Raman, and UV-vis absorption spectroscopy. The films were assembled into coin cells to test their electrochemical properties as a lithium-ion battery anode material. The cells were cycled at various C-rates to determine the upper limits for high rate performance. Adjusting the composition in the Si(1-x)Gex system demonstrates a trade-off between rate capability and specific capacity. We show that high-capacity silicon anodes and high-rate germanium anodes are merely the two extremes; the composition of Si(1-x)Gex alloys provides a new parameter to use in electrode optimization.

Original languageEnglish (US)
Pages (from-to)2249-2257
Number of pages9
JournalACS Nano
Volume7
Issue number3
DOIs
StatePublished - Mar 26 2013

Keywords

  • germanium
  • glancing angle deposition
  • lithium-ion battery
  • SiGe
  • silicon

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)

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