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Title: Direct Evidence of Lithium-Induced Atomic Ordering in Amorphous TiO2 Nanotubes

In this paper, we report the first direct chemical and imaging evidence of lithium-induced atomic ordering in amorphous TiO2 nanomaterials and propose new reaction mechanisms that contradict the many works in the published literature on the lithiation behavior of these materials. The lithiation process was conducted in situ inside an atomic resolution transmission electron microscope. Our results indicate that the lithiation started with the valence reduction of Ti4+ to Ti3+ leading to a LixTiO2 intercalation compound. The continued intercalation of Li ions in TiO2 nanotubes triggered an amorphous to crystalline phase transformation. The crystals were formed as nano-islands and identified to be Li2Ti2O4 with cubic structure (a = 8.375 Å). The tendency for the formation of these crystals was verified with density functional theory (DFT) simulations. The size of the crystalline islands provides a characteristic length scale (~5 nm) at which the atomic bonding configuration has been changed within a short time period. This phase transformation is associated with local inhomogeneities in Li distribution. On the basis of these observations, a new reaction mechanism is proposed to explain the first cycle lithiation behavior in amorphous TiO2 nanotubes.
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [1] ;  [3]
  1. Michigan Technological Univ., Houghton, MI (United States)
  2. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  3. Michigan Technological Univ., Houghton, MI (United States); Univ. of Illinois, Chicago, IL (United States)
  4. Univ. of Illinois, Chicago, IL (United States)
Publication Date:
OSTI Identifier:
Report Number(s):
Journal ID: ISSN 0897-4756; 48146
DOE Contract Number:
Resource Type:
Journal Article
Resource Relation:
Journal Name: Chemistry of Materials; Journal Volume: 26; Journal Issue: 4
American Chemical Society (ACS)
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (United States), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
Country of Publication:
United States
77 NANOSCIENCE AND NANOTECHNOLOGY Environmental Molecular Sciences Laboratory