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Title: Lithium Insertion Chemistry of Some Iron Vanadates

Abstract

Lithium insertion into various iron vanadates has been investigated. Fe{sub 2}V{sub 4}O{sub 13} and Fe{sub 4}(V{sub 2}O{sub 7}){sub 3} {center_dot} 3H{sub 2}O have discharge capacities approaching 200 mAh/g above 2.0 V vs. Li{sup +}/Li. Although the potential profiles change significantly between the first and subsequent discharges, capacity retention is unexpectedly good. Other phases, structurally related to FeVO{sub 4}, containing copper and/or sodium ions were also studied. One of these, {beta}-Cu{sub 3}Fe{sub 4}(VO{sub 4}){sub 6}, reversibly consumes almost 10 moles of electrons per formula unit (ca. 240 mAh g{sup -1}) between 3.6 and 2.0 V vs. Li{sup +}/Li, in a non-classical insertion process. It is proposed that both copper and vanadium are electrochemically active, whereas iron(III) reacts to form LiFe{sup III}O{sub 2}. The capacity of the Cu{sub 3}Fe{sub 4}(VO{sub 4}){sub 6}/Li system is nearly independent of cycling rate, stabilizing after a few cycles at 120-140 mAh g{sup -1}. Iron vanadates exhibit better capacities than their phosphate analogues, whereas the latter display more constant discharge potentials.

Authors:
;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
928486
Report Number(s):
LBNL-61528
Journal ID: ISSN 1388-2481; R&D Project: 000000; BnR: VT0301030; TRN: US200815%%345
DOE Contract Number:
DE-AC02-05CH11231
Resource Type:
Journal Article
Resource Relation:
Journal Name: Electrochemistry Communications; Journal Volume: 9; Journal Issue: 3; Related Information: Journal Publication Date: 03/2007
Country of Publication:
United States
Language:
English
Subject:
25; CAPACITY; CHEMISTRY; COPPER; ELECTRONS; IRON; LITHIUM; PHOSPHATES; RETENTION; SODIUM IONS; VANADATES; VANADIUM

Citation Formats

Patoux, Sebastien, and Richardson, Thomas J. Lithium Insertion Chemistry of Some Iron Vanadates. United States: N. p., 2007. Web. doi:10.1016/j.elecom.2006.10.006.
Patoux, Sebastien, & Richardson, Thomas J. Lithium Insertion Chemistry of Some Iron Vanadates. United States. doi:10.1016/j.elecom.2006.10.006.
Patoux, Sebastien, and Richardson, Thomas J. Fri . "Lithium Insertion Chemistry of Some Iron Vanadates". United States. doi:10.1016/j.elecom.2006.10.006. https://www.osti.gov/servlets/purl/928486.
@article{osti_928486,
title = {Lithium Insertion Chemistry of Some Iron Vanadates},
author = {Patoux, Sebastien and Richardson, Thomas J.},
abstractNote = {Lithium insertion into various iron vanadates has been investigated. Fe{sub 2}V{sub 4}O{sub 13} and Fe{sub 4}(V{sub 2}O{sub 7}){sub 3} {center_dot} 3H{sub 2}O have discharge capacities approaching 200 mAh/g above 2.0 V vs. Li{sup +}/Li. Although the potential profiles change significantly between the first and subsequent discharges, capacity retention is unexpectedly good. Other phases, structurally related to FeVO{sub 4}, containing copper and/or sodium ions were also studied. One of these, {beta}-Cu{sub 3}Fe{sub 4}(VO{sub 4}){sub 6}, reversibly consumes almost 10 moles of electrons per formula unit (ca. 240 mAh g{sup -1}) between 3.6 and 2.0 V vs. Li{sup +}/Li, in a non-classical insertion process. It is proposed that both copper and vanadium are electrochemically active, whereas iron(III) reacts to form LiFe{sup III}O{sub 2}. The capacity of the Cu{sub 3}Fe{sub 4}(VO{sub 4}){sub 6}/Li system is nearly independent of cycling rate, stabilizing after a few cycles at 120-140 mAh g{sup -1}. Iron vanadates exhibit better capacities than their phosphate analogues, whereas the latter display more constant discharge potentials.},
doi = {10.1016/j.elecom.2006.10.006},
journal = {Electrochemistry Communications},
number = 3,
volume = 9,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • The ambient temperature preparation and characterization of Li{sub {ital x}}Fe{sub 2}O{sub 3}, Li{sub {ital x}}WO{sub 2}, and {beta}-LiAl with potential applications as alternative anodes for secondary Li batteries are described. Both {alpha} and {gamma} forms of Fe{sub 2}O{sub 3} were found to insert a maximum of six Li/Fe{sub 2}O{sub 3} both electrochemically and chemically. The potential plateaus associated with the electrochemical reduction of the two forms of Fe{sub 2}O{sub 3} varied slightly. Both {alpha}-Li{sub 6}Fe{sub 2}O{sub 3} and {gamma}-Li{sub 6}Fe{sub 2}O{sub 3} were amorphous and showed a practically useful rechargeable capacity of about 1 equiv of Li at the moderatemore » rate of 0.5 mA/cm{sup 2}. Li{sub {ital x}}WO{sub 2} also loses substantial crystallinity upon Li insertion. However, most of the crystallinity was regained upon removal of the Li. It was found to be capable of cycling nearly 1 equiv of Li at low rates. Several Li-Al alloys having the {beta}-LiAl structure were prepared at ambient temperature from Al powder and Li-naphthalide. The rechargeability of the chemically prepared {beta}-LiAl was poor.« less
  • The lithium insertion chemistry of an iron phosphate withthe lipscombite structure, Fe1.19PO4F0.11(OH)0.46(H2O)0.43, wasinvestigated by X-ray diffraction (XRD), galvanostatic cycling, andpotentiostatic intermittent titration. The compound, prepared by a simplehydrothermal method, contains interconnecting chains of face-sharing FeO6octahedra with about 60 percent Fe occupancy. Assuming that all the ironmay bereduced, the theoretical capacity is about 180 mAh g?1, similar tothat of olivine-type LiFePO4. Reversible intercalation was found toproceed via a single-phase reaction at an average potential of 2.8Vversus Li+/Li. Good structural stability uponntercalation/deintercalation was observed. The unit cell volume increasedlinearly and isotropically with increasing lithium content, reaching 10percent for a Li:Fe ratio ofmore » 0.96.XRD peak widths increased onlithiation, presumably due to disorder created by conversion of Fe3+ tothe larger Fe2+, but decreased onsubsequent delithiation. The ratecapability of this material appears to be diffusion-limited, and maybenefit from a decrease in particle size. The lithium insertion behaviorof a related compound, Ti5O4(PO4)4, was also investigated.« less
  • The mechanism of lithium insertion that occurs in an iron oxyfluoride sample with a hexagonal–tungsten–bronze (HTB)-type structure was investigated by the pair distribution function. This study reveals that upon lithiation, the HTB framework collapses to yield disordered rutile and rock salt phases followed by a conversion reaction of the fluoride phase toward lithium fluoride and nanometer-sized metallic iron. The occurrence of anionic vacancies in the pristine framework was shown to strongly impact the electrochemical activity, that is, the reversible capacity scales with the content of anionic vacancies. Similar to FeOF-type electrodes, upon de-lithiation, a disordered rutile phase forms, showing thatmore » the anionic chemistry dictates the atomic arrangement of the re-oxidized phase. Finally, it was shown that the nanoscaling and structural rearrangement induced by the conversion reaction allow the in situ formation of new electrode materials with enhanced electrochemical properties.« less
  • The mechanism of lithium insertion that occurs in an iron oxyfluoride sample with a hexagonal–tungsten–bronze (HTB)-type structure was investigated by the pair distribution function. This study reveals that upon lithiation, the HTB framework collapses to yield disordered rutile and rock salt phases followed by a conversion reaction of the fluoride phase toward lithium fluoride and nanometer-sized metallic iron. The occurrence of anionic vacancies in the pristine framework was shown to strongly impact the electrochemical activity, that is, the reversible capacity scales with the content of anionic vacancies. Similar to FeOF-type electrodes, upon de-lithiation, a disordered rutile phase forms, showing thatmore » the anionic chemistry dictates the atomic arrangement of the re-oxidized phase. Finally, it was shown that the nanoscaling and structural rearrangement induced by the conversion reaction allow the in situ formation of new electrode materials with enhanced electrochemical properties.« less
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