Mechanical Properties and Chemical Reactivity of LixSiOy Thin Films

Yun Xu, Caleb Stetson, Kevin Wood, Eric Sivonxay, Chunsheng Jiang, Glenn Teeter, Svitlana Pylypenko, Sang Don Han, Kristin A. Persson, Anthony Burrell, Andriy Zakutayev

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22 Scopus Citations


Silicon (Si) is a commonly studied candidate material for next-generation anodes in Li-ion batteries. A native oxide SiO 2 on Si is often inevitable. However, it is not clear if this layer has a positive or negative effect on the battery performance. This understanding is complicated by the lack of knowledge about the physical properties of the SiO 2 lithiation products and by the convolution of chemical and electrochemical effects during the anode lithiation process. In this study, Li x SiO y thin films as model materials for lithiated SiO 2 were deposited by magnetron sputtering at ambient temperature, with the goal of (1) decoupling chemical reactivity from electrochemical reactivity and (2) evaluating the physical and electrochemical properties of Li x SiO y . X-ray photoemission spectroscopy analysis of the deposited thin films demonstrate that a composition close to previous experimental reports of lithiated native SiO 2 can be achieved through sputtering. Our density functional theory calculations also confirm that the possible phases formed by lithiating SiO 2 are very close to the measured film compositions. Scanning probe microscopy measurements show that the mechanical properties of the film are strongly dependent on lithium concentration, with a ductile behavior at a higher Li content and a brittle behavior at a lower Li content. The chemical reactivity of the thin films was investigated by measuring the AC impedance evolution, suggesting that Li x SiO y continuously reacts with the electrolyte, in part because of the high electronic conductivity of the film determined from solid-state impedance measurements. The electrochemical cycling data of the sputter-deposited Li x SiO y /Si films also suggest that Li x SiO y is not beneficial in stabilizing the Si anode surface during battery operation, despite its favorable mechanical properties.

Original languageAmerican English
Pages (from-to)38558-38564
Number of pages7
JournalACS Applied Materials and Interfaces
Issue number44
StatePublished - 7 Nov 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5K00-72507


  • chemical reactivity
  • Li SiO
  • lithium ion batteries
  • mechanical properties
  • solid electrolyte interphases


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