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Title: EELS Valence Mapping in Electron Beam Sensitive FeFx/C Nanocomposites

Abstract

A new type of positive electrodes for Li-Ion batteries has been synthesized based on FeF{sub 2}/C and FeF3/C nanocomposites with particle size in the 8-12 nm range [1]. The measured high capacities rely on a complete reduction of Fe to its metallic state according to the following reaction: xLi{sup +}+xe{sup -} +Fe{sup x+}Fx = xLiF + Fe{sup 0}, where x=3 and x=2 for FeF3/C and FeF2/C respectively. This electrochemical reaction involves a change in valence state of Fe from 3+ or 2+ to 0 that can be determined uniquely by EELS from the peak energy of the L{sub 3} line and from the L{sub 3}/L{sub 2} line intensity ratio. In this paper, we report EELS mapping results on the electrochemical conversion processes and in particular the mapping of the Fe valence state before and after discharge. This work was performed with a Hitachi HF2000 equipped with a Gatan PEELS and with a FEI CM200 FEG TEM equipped with a Gatan GIF. Both instruments were operated in STEM mode at 200kV with an EELS collection half angle of {beta}=5 mrad and spectrum imaging software.

Authors:
 [1];  [1];  [1];  [2]
  1. Rutgers University
  2. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Shared Research Equipment Collaborative Research Center
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
931892
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: Microscopy and Microanalysis 2007, Fort Lauderdale, FL, USA, 20070805, 20070809
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; 77 NANOSCIENCE AND NANOTECHNOLOGY; METAL-NONMETAL BATTERIES; LITHIUM; IRON FLUORIDES; CARBON; NANOSTRUCTURES; COMPOSITE MATERIALS; ELECTROCHEMISTRY; VALENCE; ENERGY-LOSS SPECTROSCOPY; TEM; EELS; Valence Mapping; nanocomposite; FeF2; beam-sensitive material; battery electrode

Citation Formats

Cosandey, F., Al-Sharab, J.F., Amatucci, Glenn G., and Bentley, James. EELS Valence Mapping in Electron Beam Sensitive FeFx/C Nanocomposites. United States: N. p., 2007. Web.
Cosandey, F., Al-Sharab, J.F., Amatucci, Glenn G., & Bentley, James. EELS Valence Mapping in Electron Beam Sensitive FeFx/C Nanocomposites. United States.
Cosandey, F., Al-Sharab, J.F., Amatucci, Glenn G., and Bentley, James. Mon . "EELS Valence Mapping in Electron Beam Sensitive FeFx/C Nanocomposites". United States. doi:.
@article{osti_931892,
title = {EELS Valence Mapping in Electron Beam Sensitive FeFx/C Nanocomposites},
author = {Cosandey, F. and Al-Sharab, J.F. and Amatucci, Glenn G. and Bentley, James},
abstractNote = {A new type of positive electrodes for Li-Ion batteries has been synthesized based on FeF{sub 2}/C and FeF3/C nanocomposites with particle size in the 8-12 nm range [1]. The measured high capacities rely on a complete reduction of Fe to its metallic state according to the following reaction: xLi{sup +}+xe{sup -} +Fe{sup x+}Fx = xLiF + Fe{sup 0}, where x=3 and x=2 for FeF3/C and FeF2/C respectively. This electrochemical reaction involves a change in valence state of Fe from 3+ or 2+ to 0 that can be determined uniquely by EELS from the peak energy of the L{sub 3} line and from the L{sub 3}/L{sub 2} line intensity ratio. In this paper, we report EELS mapping results on the electrochemical conversion processes and in particular the mapping of the Fe valence state before and after discharge. This work was performed with a Hitachi HF2000 equipped with a Gatan PEELS and with a FEI CM200 FEG TEM equipped with a Gatan GIF. Both instruments were operated in STEM mode at 200kV with an EELS collection half angle of {beta}=5 mrad and spectrum imaging software.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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