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Title: Size dependent behavior of Fe 3O 4 crystals during electrochemical (de)lithiation: an in situ X-ray diffraction, ex situ X-ray absorption spectroscopy, transmission electron microscopy and theoretical investigation

Here, the iron oxide magnetite, Fe 3O 4, is a promising conversion type lithium ion battery anode material due to its high natural abundance, low cost and high theoretical capacity. While the close packing of ions in the inverse spinel structure of Fe 3O 4 enables high energy density, it also limits the kinetics of lithium ion diffusion in the material. Nanosizing of Fe 3O 4 to reduce the diffusion path length is an effective strategy for overcoming this issue and results in improved rate capability. However, the impact of nanosizing on the multiple structural transformations that occur during the electrochemical (de)lithiation reaction in Fe 3O 4 is poorly understood. In this study, the influence of crystallite size on the lithiation-conversion mechanisms in Fe 3O 4 is investigated using complementary X-ray techniques along with transmission electron microscopy (TEM) and continuum level simulations on electrodes of two different Fe 3O 4 crystallite sizes. In situ X-ray diffraction (XRD) measurements were utilized to track the changes to the crystalline phases during (de)lithiation. X-ray absorption spectroscopy (XAS) measurements at multiple points during the (de)lithiation processes provided local electronic and atomic structural information. Tracking the crystalline and nanocrystalline phases during the first (de)lithiation providesmore » experimental evidence that (1) the lithiation mechanism is non-uniform and dependent on crystallite size, where increased Li + diffusion length in larger crystals results in conversion to Fe 0 metal while insertion of Li + into spinel-Fe 3O 4 is still occurring, and (2) the disorder and size of the Fe metal domains formed when either material is fully lithiated impacts the homogeneity of the FeO phase formed during the subsequent delithiation.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [4] ;  [2] ; ORCiD logo [5] ;  [2] ; ORCiD logo [2]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States)
  2. Stony Brook Univ., Stony Brook, NY (United States)
  3. Columbia Univ., New York, NY (United States)
  4. American Physical Society, Ridge, NY (United States)
  5. Brookhaven National Lab. (BNL), Upton, NY (United States); Stony Brook Univ., Stony Brook, NY (United States)
Publication Date:
Report Number(s):
BNL-114433-2017-JA
Journal ID: ISSN 1463-9076; PPCPFQ; TRN: US1703237
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Physical Chemistry Chemical Physics. PCCP (Print)
Additional Journal Information:
Journal Name: Physical Chemistry Chemical Physics. PCCP (Print); Journal Volume: 19; Journal Issue: 31; Journal ID: ISSN 1463-9076
Publisher:
Royal Society of Chemistry
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V)
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE
OSTI Identifier:
1402423