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Title: Elucidating the Phase Transformation of Li 4Ti 5O 12 Lithiation at the Nanoscale

Here this work provides insight regarding the fundamental lithiation and delithiation mechanism of the popular lithium ion battery anode material, Li 4Ti 5O 12 (LTO). Our results quantify the extent of reaction between Li 4Ti 5O 12 and Li 7Ti 5O 12 at the nanoscale, during the first cycle. Lithium titanate’s discharge (lithiation) and charge (delithiation) reactions are notoriously difficult to characterize due to the zero-strain transition occurring between the end members Li 4Ti 5O 12 and Li 7Ti 5O 12. Interestingly, however, the latter compound is electronically conductive, while the former is an insulator. We take advantage of this critical property difference by using conductive atomic force microscopy (c-AFM) to locally monitor the phase transition between the two structures at various states of charge. To do so, we perform ex situ characterization on electrochemically cycled LTO thin-films that are never exposed to air. We provide direct confirmation of the manner in which the reaction occurs, which proceeds via percolation channels within single grains. We complement scanning probe analyses with an X-ray photoelectron spectroscopy (XPS) study that identifies and explains changes in the LTO surface structure and composition. Additionally, we provide a computational analysis to describe the unique electronic differencesmore » between LTO and its lithiated form.« less
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [1] ;  [1]
  1. Univ. of California, San Diego, CA (United States). Dept. of NanoEngineering
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
  4. Univ. of California, San Diego, CA (United States). Materials Science & Engineering Program
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 10; Journal Issue: 4; Journal ID: ISSN 1936-0851
American Chemical Society (ACS)
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
36 MATERIALS SCIENCE; anode; c-AFM; Li-ion battery; Li4Ti5O12; LTO; thin-film; XPS
OSTI Identifier: