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| 2. |
- Gejke, Cecilia, 1973, et al.
(författare)
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The effect of lithium insertion on the structure of tin oxide-based glasses
- 2001
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Ingår i: Journal of Power Sources. - 0378-7753. ; 97-98, s. 226-228.
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Tidskriftsartikel (refereegranskat)abstract
- Two different SnO-based glasses, Sn2B3O6.5 and Sn2B2AlO6.5, have been examd. with FT-IR and Raman spectroscopy at different stages during the first electrochemical cycle. Some disruption of the connection between borate units in the network occurred during cycling. There was also an irreversible formation of Li3BO3 that can be related to the large capacity loss.
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| 3. |
- Kus, Hulya, et al.
(författare)
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In-use performance of rendered autoclaved aerated concrete walls by long-term moisture monitoring
- 2004
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Ingår i: Building and Environment. - : Elsevier Ltd. - 0360-1323 .- 1873-684X. ; 39:6, s. 677-687
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Tidskriftsartikel (refereegranskat)abstract
- The importance of long-term performance and durability of building materials and components has received increasing consideration with regard to a sustainable built environment. Degradation due to exposure to environment conditions, particularly driving rain, play a significant role in the service life of porous materials used in external wall components. Microenvironment monitoring data are presented in this paper to show how different surface coatings can contribute to moisture performance of external walls made of autoclaved aerated concrete (AAC). Renderings modifed with hydrophobic products on AAC substrate prove to have less wetting and better drying properties than unmodified renderings according to the performance assessment based on the amount and duration of moisture measured in the material.
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| 4. |
- Gejke, Cecilia, 1973, et al.
(författare)
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Structural investigation of the Li+ ion insertion/extraction mechanism in Sn-based composite oxide glasses
- 2001
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Ingår i: Journal of Physics and Chemistry of Solids. - 0022-3697. ; 62, s. 1213-1218.
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Tidskriftsartikel (refereegranskat)abstract
- The effect of lithium insertion for two Sn-based composite oxide glasses, Sn2BPO6 and Sn2P2O7, was examined during the first electrochemical discharge/charge cycle. Electrodes based on these glasses were analysed with micro-Raman spectroscopy at different steps during the cycle. In-situ X-ray diffraction has been used to confirm the amorphous state during the lithium insertion and extraction process. No alloy formation between Li and Sn could be discerned throughout the first cycle. It was found that when lithium enters the electrode, a reaction at the surface of the glass particles takes place resulting in Li3PO4, Li2O and SnO2 formation. The charge compensation mechanism is thought to be the reduction of Sn2+ to Sn. The formation of Li3PO4 is found to be irreversible and is as such partly responsible for the large observed capacity loss during the first cycle.
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| 5. |
- Neimert-Andersson, Kristina, et al.
(författare)
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Stereoselective Synthesis of Polyhydroxyl Surfactants. Stereochemical Influence on Langmuir Monolayers
- 2004
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Ingår i: Journal of Organic Chemistry. - : American Chemical Society (ACS). - 0022-3263 .- 1520-6904. ; 69:11, s. 3746-3752
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Tidskriftsartikel (refereegranskat)abstract
- Herein is described the synthesis of surfactants featuring polyhydroxylated head groups. Three head groups were prepared via consecutive stereoselective dihydroxylations of a diene. By coupling of these with lipophilic tail groups six novel surfactants have been prepared. The monolayers prepared from four of these have been investigated at the air-water interface. Significant differences were observed between monolayers consisting of enantiomerically pure surfactants contra racemates as well as between diastereomers.
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| 6. |
- Dyson, P J, et al.
(författare)
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Determination of hydrogen concentration in ionic liquids and the effect (or lack of) on rates of hydrogenation
- 2003
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; :19, s. 2418-2419
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Tidskriftsartikel (refereegranskat)abstract
- The solubility of hydrogen and the corresponding Henry coefficients for 11 ionic liquids have been determined in situ at 100 atm H(2) pressure and are much lower than expected; attempts to correlate the solubility of hydrogen in the ionic liquids with the rate of reaction for the hydrogenation of benzene to cyclohexane in these solvents have been made.
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| 7. |
- Schmitt, Thorsten, et al.
(författare)
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Li insertion into V6O13 battery cathodes studies by soft x-ray spectroscopies
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 95:11, s. 6444-6449
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Tidskriftsartikel (refereegranskat)abstract
- Changes in the electronic structure of V6O13 on lithium-ion insertion into battery cathod were studied by soft x-ray absorption (SXA) spectroscopy and resonant soft x-ray emission (SXE) spectroscopy. SXA and resonant SXE spectra were recorded ex situ for cycled battery cathodes discharged to different potentials corresponding closely to distinct lithiated stages (LixV6O13,x=0,1,...,6).Large systematic change were observed in the vanadium and oxygen x-ray spectra, reflecting the effects of electrochemical reduction associated with the Li-ion insertion. Spectral shape analysis indicates that a large fraction of the vanadium ions have been reduced to V3+ ions for the highest degree of, x=6. Neverrtheless, further lithiation may be possible, in view of the linear development of the vanadium and oxygen bands on charge uptake.
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| 8. |
- Wang, Zeng, et al.
(författare)
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Zeolite coated ATR crystals for new applications in FTIR-ATR spectroscopy
- 2004
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Ingår i: Chemical Communications. - : Royal Society of Chemistry (RSC). - 1359-7345 .- 1364-548X. ; :24, s. 2888-2889
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Tidskriftsartikel (refereegranskat)abstract
- Thin silicalite-1 films were grown on ATR crystals and used for detection of low amounts of organic molecules in a gas flow by FTIR spectroscopy.
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| 9. |
- Andersson, Anna S.
(författare)
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Lithium iron phosphates as cathode materials in lithium batteries
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Iron-based oxides are perhaps the only realistic cathode materials for electric and electric-hybrid vehicle applications. Two types of lithium iron phosphate, LiFePO4 andR-Li3Fe2(PO4)3, have been investigated for use within the lithium/lithium-ion polymer batteryconcept. The main techniques exploited have been: electrochemical cycling; X-ray andneutron diffraction - to study structural changes of the host material during lithiuminsertion/extraction; Mössbauer spectroscopy - to probe changes in the local structure of theFe atoms.Lithium extraction/insertion for LiFePO4, (olivine-type structure) has been followed by acombination of in situ X-ray diffraction and in situ Mössbauer spectroscopy. QuantitativeRietveld analysis of diffraction data has given good agreement with electrochemical andMössbauer spectroscopy data: ca. 20% of the LiFePO4 phase remains after charging. Possiblemechanisms to describe the capacity loss are proposed. High-temperature cycling (at 40oC and60oC) has shown the specific capacity to be markedly enhanced at higher temperatures.In situ Mössbauer spectroscopy has also been used to study the insertion of lithium into R-Li3Fe2(PO4)3. The two non-equivalent Fe3+ ions cannot be distinguished, whereas two typesof Fe2+ site appear on lithium insertion. Lithium appears to enter a site closer to one of theFe atoms. Elevated-temperature cycling shows the temperature dependence of R-Li3Fe2(PO4)3to be less marked than for the LiFePO4 system.The magnetic properties of R-Li3Fe2(PO4)3 have been investigated for the first time: a para- to antiferromagnetic transition is seen at 28 ~ K. Neutron powder diffraction shows that the Fe magnetic dipoles lie close to the ab-plane and are ferromagnetically aligned within an Fesheet perpendicular to the c-axis, but are antiferromagnetically coupled to adjacent sheets.
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| 10. |
- Björk, Helen, 1973-
(författare)
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Cooperative Lithium-Ion Insertion Mechanisms in Cathode Materials for Battery Applications
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Understanding lithium-ion insertion/extraction mechanisms in battery electrode materials is of crucial importance in developing new materials with better cycling performance. In this thesis, these mechanisms are probed for two different potential cathode materials by a combination of electrochemical and single-crystal X-ray diffraction studies. The materials investigated are V6O13 and cubic LiMn2O4 spinel.Single-crystal X-ray diffraction studies of lithiated phases in the LixV6O13 system (x=2/3 and 1) exhibit superlattice phenomena and an underlying Li+ ion insertion mechanism which involves the stepwise addition of Li+ ions into a two-dimensional array of chemically equivalent sites. Each successive stage in the insertion process is accompanied by a rearrangement of the Li+ ions together with an electron redistribution associated with the reduction of specific V-atoms in the structure. This results in the formation of electrochemically active sheets in the structure. A similar mechanism occurs in the LiMn2O4 delithiation process, whereby lithium is extracted in a layered arrangement, with the Mn atoms forming charge-ordered Mn3+/Mn4+ layers.Lithium-ion insertion/extraction processes in transition-metal oxides would thus seem to occur through an ordered two-dimensional arrangement of lithium ions extending throughout the structure. The lithium ions and the host structure rearrange cooperatively to form superlattices through lithium and transition-metal ion charge-ordering. A picture begins to emerge of a universal two-dimensional lithium-ion insertion/extraction mechanism analogous to the familiar staging sequence in graphite.
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