Nanostructured Si(1-x)Gex for Tunable Thin Film Lithium-Ion Battery Anodes

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• 作者：Paul R. Abel ; Aaron M. Chockla ; Yong-Mao Lin ; Vincent C. Holmberg ; Justin T. Harris ; Brian A. Korgel ; Adam Heller ; C. Buddie Mullins
• 刊名：ACS Nano
• 出版年：2013
• 出版时间：March 26, 2013
• 年：2013
• 卷：7
• 期：3
• 页码：2249-2257
• 全文大小：604K
• 年卷期：v.7,no.3(March 26, 2013)
• ISSN：1936-086X

文摘

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)Ge_x 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鈥檚 composition and physical properties were investigated by X-ray photoelectron spectroscopy, four-point probe conductivity, Raman, and UV鈥搗is 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)Ge_x 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)Ge_x alloys provides a new parameter to use in electrode optimization.

Keywords:

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