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Title: Atomistic Conversion Reaction Mechanism of WO 3 in Secondary Ion Batteries of Li, Na, and Ca

Reversible insertion and extraction of ionic species into a host lattice governs the basic operating principle for both rechargeable battery (such as lithium batteries) and electrochromic devices (such as ANA Boeing 787-8 Dreamliner electrochromic window). Intercalation and/or conversion are two fundamental chemical processes for some materials in response to the ion insertion. The interplay between these two chemical processes has never been established. It is speculated that the conversion reaction is initiated by ion intercalation. However, experimental evidence of intercalation and subsequent conversion remains unexplored. Here, using in situ HRTEM and spectroscopy, we captured the atomistic conversion reaction processes during lithium, sodium and calcium ion insertion into tungsten trioxide (WO3) single crystal model electrodes. An intercalation step right prior to conversion is explicitly revealed at atomic scale for the first time for these three ion species. Combining nanoscale diffraction and ab initio molecular dynamics simulations, it is found that, beyond intercalation, the inserted ion-oxygen bonding formation destabilized the transition-metal framework which gradually shrunk, distorted and finally collapsed to a pseudo-amorphous structure. This study provides a full atomistic picture on the transition from intercalation to conversion, which is of essential for material applications in both secondary ion batteries and electrochromic devices.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5] ;  [2] ;  [1] ;  [2]
  1. Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh PA 15261 USA
  2. Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99352 USA
  3. School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 China
  4. Energy and Environmental Directorate, Pacific Northwest National Laboratory, Richland WA 99352 USA
  5. Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor MI 48109 USA
Publication Date:
OSTI Identifier:
1327104
Report Number(s):
PNNL-SA-114899
Journal ID: ISSN 1433-7851; 48379; KP1704020
DOE Contract Number:
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 55; Journal Issue: 21
Publisher:
Wiley
Research Org:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
WO3; intercalation; conversion; lithium ion batteries; secondary ion batteries; in situ TEM; Environmental Molecular Sciences Laboratory