uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
The Lithium Extraction/Insertion Mechanism in Li2FeSiO4
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
Show others and affiliations
2006 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 16, 2266-2272 p.Article in journal (Refereed) Published
Abstract [en]

The lithium extraction and insertion mechanism in the cathode material Li2FeSiO4 has been monitored by in situ X-ray diffraction and Mössbauer spectroscopy during the first two cycles. The residual amounts of Li2FeSiO4 and LiFeSiO4 in the fully charged and discharged states are 5% and 10%, respectively, on the basis of both Mössbauer spectroscopy and powder XRD studies; this is also in good agreement with the results of electrochemical measurements. The observed lowering of the potential plateau from 3.10 to 2.80 V during the first cycle can be explained by a structural rearrangement in which some of the Li ions (in the 4b site) and Fe ions (in the 2a site) become interchanged.

Place, publisher, year, edition, pages
2006. Vol. 16, 2266-2272 p.
National Category
Inorganic Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-93796DOI: 10.1039/B601184EOAI: oai:DiVA.org:uu-93796DiVA: diva2:167387
Available from: 2005-11-17 Created: 2005-11-17 Last updated: 2017-12-14Bibliographically approved
In thesis
1. 3d Transition Metals Studied by Mössbauer Spectroscopy
Open this publication in new window or tab >>3d Transition Metals Studied by Mössbauer Spectroscopy
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Layered crystals with magnetic elements as Co and Fe have been studied. In TlCo2Se2, where Co atoms in one sheet are separated by Tl and Se from the next Co sheet, magnetic interaction within and between the sheets have been studied. Samples doped with 4% 57Fe replaced Co, show a magnetic spiral character with hyperfine fields in a flower shape in the ab-plane. The magnetic moment of 0.46 μB per Co atom derived from the average field is in good agreement with the result from neutron diffraction. In TlCu1.73Fe0.27Se2 the easy axis of magnetisation is the c-axis. The magnetic moment calculated from the Mössbauer data and SQUID magnetrometry is 0.97 μB per Fe atom with TC = 55(5) K.

Multilayers of different elements have been studied. The effect of vanadium atoms on iron atoms at the interface of FeNi/V multilayers has been determined and the intermixing at the interface has been calculated to be 2-3 monolayers. For FeNi/Co 1/1 monolayer the magnetic hyperfine field (Bhf) is 45° out-of-plane, while for superlattices containing 2 to 5 monolayers it is in the plane. An study on Fe/Co superlattice were done by experimental, theoretical and simulational methods. The Bhf is highest for the Fe at the second layer next to the interface and gets the bulk value in the centre of thicker Fe layers.

Studied magnetic nanoparticles coated with a lipid bilayer (magnetoliposomes) are found to have the magnetite structure but being non-stoichiometric as a result of the manufacturing process. The composition was approximately 32% γ-Fe2O3 and 68% Fe3O4. The oxidation evolution and its effect on magnetic properties of Fe clusters were also studied by means of different techniques.

The extraction and insertion mechanism of lithium in the cathode material Li2FeSiO4 has been monitored by in situ x-ray diffraction and Mössbauer spectroscopy during the first two cycles. The relative amount of Fe+3/ Fe+2 at each end state was in good agreement with the results obtained from electrochemical measurements. A possible explanation to the observed lowering of the potential plateau from 3.10 to 2.80 V occurring during the first cycle, involves a structural rearrangement process in which some of the Li ions and the Fe ions are interchanged.

The behaviour of small amounts of Fe in brass is investigated using Mössbauer spectroscopy. It was shown that a heat treatment can increase the amount of the precipitates of γ-Fe and ~650° C is the optimal treatment for having the highest amount of this phase.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2005. viii + 86 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 122
Keyword
Physics, Mössbauer Spectroscopy, SQUID Magnetometry, XRD, Layered Structures, Magnetism, Magnetic Superlattices, Nanoparticles, Li-ion Batteries, Brass, Fysik
National Category
Physical Sciences
Identifiers
urn:nbn:se:uu:diva-6163 (URN)91-554-6409-2 (ISBN)
Public defence
2005-12-09, Polhemssalen, Ångström Laboratoriet, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2005-11-17 Created: 2005-11-17 Last updated: 2009-05-04Bibliographically approved
2. Low-Cost Iron-Based Cathode Materials for Large-Scale Battery Applications
Open this publication in new window or tab >>Low-Cost Iron-Based Cathode Materials for Large-Scale Battery Applications
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There are today clear indications that the Li-ion battery of the type currently used worldwide in mobile-phones and lap-tops is also destined to soon become the battery of choice in more energy-demanding concepts such as electric and electric hybrid vehicles (EVs and EHVs). Since the currently used cathode materials (typically of the Li(Ni,Co)O2-type) are too expensive in large-scale applications, these new batteries will have to exploit some much cheaper transition-metal. Ideally, this should be the very cheapest - iron(Fe) - in combination with a graphite(C)-based anode. In this context, the obvious Fe-based active cathode of choice appears to be LiFePO4. A second and in some ways even more attractive material - Li2FeSiO4 - has emerged during the course of this work.

An effort has here been made to understand the Li extraction/insertion mechanism on electrochemical cycling of Li2FeSiO4. A fascinating picture has emerged (following a complex combination of Mössbauer, X-ray diffraction and electrochemical studies) in which the material is seen to cycle between Li2FeSiO4 and LiFeSiO4, but with the structure of the original Li2FeSiO4 transforming from a metastable short-range ordered solid-solution into a more stable long-range ordered structure during the first cycle. Density Functional Theory calculations on Li2FeSiO4 and the delithiated on LiFeSiO4 structure provide an interesting insight into the experimental result.

Photoelectron spectroscopy was used to study the surface chemistry of both carbon-treated LiFePO4 and Li2FeSiO4 after electrochemical cycling. The surface-layer on both materials was concluded to be very thin and with incomplete coverage, giving the promise of good long-term cycling.

LiFePO4 and Li2FeSiO4 should both be seen as highly promising candidates as positive-electrode materials for large-scale Li-ion battery applications.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 54 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 179
Keyword
Inorganic chemistry, Li-ion battery, cathode material, lithium iron phosphate, lithium iron silicate, X-ray powder diffraction, Mössbauer spectroscopy, photoelectron spectroscopy, Oorganisk kemi
Identifiers
urn:nbn:se:uu:diva-6842 (URN)91-554-6559-5 (ISBN)
Public defence
2006-05-12, Häggsalen, The Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 10:15
Opponent
Supervisors
Available from: 2006-04-21 Created: 2006-04-21 Last updated: 2013-05-17Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Häggström, LennartGustafsson, Torbjörn

Search in DiVA

By author/editor
Häggström, LennartGustafsson, Torbjörn
By organisation
Department of Materials ChemistryDepartment of Physics
In the same journal
Journal of Materials Chemistry
Inorganic Chemistry

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 1157 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf