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Title: Probing microstructure and phase evolution of α-MoO 3 nanobelts for sodium-ion batteries by in situ transmission electron microscopy

The fundamental electrochemical reaction mechanisms and the phase transformation pathways of layer-structured α-MoO 3 nanobelt during the sodiation/desodiation process to date remain largely unknown. In this study, to observe the real-time sodiation/desodiaton behaviors of α-MoO 3 during electrochemical cycling, we construct a MoO 3 anode sodium-ion battery inside a transmission electron microscope (TEM). Utilizing in situ TEM and electron diffraction pattern (EDP) observation, α-MoO 3 nanobelts are found to undergo a unique multi-step phase transformation. Upon the first sodiation, α-MoO 3 nanobelts initially form amorphous Na xMoO3 phase and are subsequently sodiated into intermediate phase of crystalline NaMoO 2, finally resulting in the crystallized Mo nanograins embedded within the Na 2O matrix. During the first desodiation process, Mo nanograins are firstly re-oxidized into intermediate phase NaMoO 2 that is further transformed into amorphous Na 2MoO 3, resulting in an irreversible phase transformation. Upon subsequent sodiation/desodiation cycles, however, a stable and reversible phase transformation between crystalline Mo and amorphous Na2MoO 3 phases has been revealed. In conclusion, our work provides an in-deepth understanding of the phase transformation pathways of α-MoO 3 nanobelts upon electrochemical sodiation/desodiation processes, with the hope of assistance in designing sodium-ion batteries with enhanced performance.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4]
  1. Southeast University, Nanjing (China). SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of the Ministry of Education
  2. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
  3. Southeast University, Nanjing (China). Department of Physics, Key Laboratory of MEMS of the Ministry of Education
  4. Southeast University, Nanjing (China). SEU-FEI Nano-Pico Center, Key Laboratory of MEMS of the Ministry of Education; Joint Research Institute of Southeast University and Monash University, Suzhou (China). Center for Advanced Materials and Manufacture
Publication Date:
Report Number(s):
BNL-112456-2016-JA
Journal ID: ISSN 2211-2855; KC0403020
Grant/Contract Number:
SC0012704; SC0012704l
Type:
Accepted Manuscript
Journal Name:
Nano Energy
Additional Journal Information:
Journal Volume: 27; Journal Issue: C; Journal ID: ISSN 2211-2855
Publisher:
Elsevier
Research Org:
Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; Sodium-ion batteries; In situ TEM; MoO3; Sodiation/desodiation; Multi-step phase transformation
OSTI Identifier:
1336074
Alternate Identifier(s):
OSTI ID: 1396391