uu.seUppsala University Publications
Change search
Refine search result
2345678 201 - 250 of 912
CiteExportLink to result list
Permanent 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
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 201.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrode/electrolyte interfaces in lithium and sodium batteries2017Conference paper (Refereed)
    Abstract [en]

    Lithium-ion batteries (LIB) and sodium-ion batteries (SIB) and their materials is today a large research area due to the practical need for efficient energy storage. SIBs show, compared to LIBs, unique electrochemical reactions that mechanistically need to be understood. The kind of materials that can host sodium ions are, for instance, structurally different from the negative and positive electrode materials for LIBs. Also interfacial reactions occurring between the electrode and the electrolyte are different from LIBs.

     

    To understand the chemical properties of electrolyte/electrode interfaces in LIBs and SIBs is one of the core research activities at the Ångström Advanced Battery Centre (ÅABC), Uppsala University. It is at these interfaces, the solid-electrolyte interphase (SEI) on the anode and the cathode electrolyte interface (CEI) on the cathode, charge transfer reactions take place, unwanted side reactions might start and the stability of the interface also influence the thermal stability of the battery. Careful characterization is therefore needed as a base for creating new and more stable interfaces for prolonged battery life. In this presentation we will make a review of several studies we have performed combining electrochemical characterization with in-house and synchrotron-based photoelectron spectroscopy (such as hard X-ray Photoelectron Spectroscopy, HAXPES). We will primarily dwell on the difference in chemical composition of the SEI of anodes used in LIBs and SIBs, respectively. We will also give some examples of ways to improve cycle life: the role of the electrolyte salt, electrolyte additives, but also of ways to protect electrode particle surfaces.

     

    We have investigated materials from three different categories of anodes: i.e. conversion, alloying, and insertion anodes. Our HAXPES results on Fe2O3 as a conversion anode material indicated that the SEI on Fe2O3 anode is thicker and more homogeneous in a SIB compared to that in an analogue Li-ion battery.1 We will discuss our work of silicon anodes for LIBs and we will discuss the dissolution of the SEI components in a SIB which is larger than for a LIB2. We will discuss the results which show that the SEI on a carbonacous anode in a SIB is inferior to that of the LIB counterpart.

     

    The interfaces of positive electrodes are also important. Often corrosion products will form during battery cycling leading to metal dissolution and poisoning of the negative electrode. We will also here compare the interfaces of Ni- and Mn-based oxide cathodes for LIBs and SIBs3.

    .

     

    References:

    [1] B. Philippe; M. Valvo; F. Lindgren; H. Rensmo; K. Edström, Chem. Mater. 2014, 26, 5028–5041.

    [2] R. Mogensen, D. Brandell, R. Younesi, ACS Energy Lett., 2016, 1, 1173–1178.

    [3] S. Doubaji, B. Philippe, I. Saadoune, M. Gorgoi, T. Gustafsson, A. Solhy, Mario Valvo, H. Rensmo, K. Edström. ChemSusChem, 2916, 9, 97-108.

     

  • 202.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Åhlund, John
    Scienta.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Recent progress in high pressure analyser and experimental method development applied to liquid/solid interface studies2015Conference paper (Refereed)
  • 203.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wang, Zhaouhui
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Nanotechnology and Functional Materials.
    Separators As a Tool for Enhanced Battery Performance2019In: International Battery Association 2019: Batteries and Energy Storage / [ed] The electrochemical Society, La Jolla, 2019, article id 117872Conference paper (Refereed)
  • 204.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sodium batteries and their interfaces2017Conference paper (Other academic)
  • 205.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lindgren, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ma, Yue
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Silicon anodes and electrolyte interactions2016Conference paper (Refereed)
  • 206.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    State of the art knowledge about interfaces and interphases in lithium and sodium batteries2018In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Article in journal (Other academic)
  • 207.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yue, Ma
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Flash, Size Tunable Synthesis of SnO2 Nanocrystals Encapsulated in 3d Macroporous Carbon and Its Pseudocapacitive Contribution to High Performance Li+ Storage2015Conference paper (Refereed)
  • 208.
    Egorov, A. V.
    et al.
    St Petersburg State Univ, St Petersburg 199034, Russia.
    Brodskaya, E. N.
    St Petersburg State Univ, St Petersburg 199034, Russia.
    Laaksonen, Aatto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, S-10691 Stockholm, Sweden.
    The Effect of Single-Atomic Ions on the Melting of Microscopic Ice Particles According to Molecular Dynamics Data2018In: Colloid Journal of the Russian Academy of Science, ISSN 1061-933X, E-ISSN 1608-3067, Vol. 80, no 5, p. 484-491Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulation of microscopic ice particles containing Ca2+, F-, Cl-, Na+, and Li+ ions has been performed in the temperature range of 20-200 K. For all the systems under consideration, phase and structural transformations accompanying their heating have been studied in detail, and the melting points have been determined. The main attention has been focused on the determination of the mechanisms of the effect of ions on the phase state of microcrystals.

  • 209.
    Ehrenborg, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Investigation of the Cr solubility in the MC phase where M = Ti, Ta2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this work the chromium solubility in MC, and M in Cr3C2 and Cr7C3 carbides in the Ti-Cr-C and Ta-Cr-C system have been examined experimentally. Special attention is given to the cubic MC phase due to its frequent use in industrial cemented carbides. A sample series was made where half of the samples were arc-melted and all samples were heat-treated at different temperatures. By arc-melting some of the samples it was possible to compare the arc-melted and non arc-melted samples to confirm equilibrium. Three phases were expected in each sample. The microstructure was examined by LOM and SEM. The phases were identified by XRD and the amount of Cr in each phase was measured by WDS in FEG-SEM or by microprobe analysis. A higher temperature for the heat-treatment allows more Cr to dissolve in the cubic carbide. Arc-melted samples allow more Cr to dissolve than the same system which has not been arc-melted. The Cr solubility in the cubic carbide in non arc-melted samples at 1400 degree Celcius is 8,1±0,4 at% in (Ti, Cr)C and 7,6±0,3 at% in (Ta, Cr)C. According to the samples the phase diagrams based on thermodynamic calculations are different to experimental data. Therefore, more experimental data should be made to update existing ternary diagrams.

    Download full text (pdf)
    fulltext
  • 210.
    Ek, Gustav
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A study of poly(vinyl alcohol) as a solid polymer electrolyte for lithium-ion batteries2016Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The use of solid polymer electrolytes in lithium-ion batteries has the advantage in

    terms of safety and processability, however they often lack in terms of performance.

    This is of major concern in applications where high current densities or rapidly

    changing currents are important. Such applications include electrical vehicles and

    energy storage of the electrical grid to accommodate fluctuations when using

    renewable energy sources such as wind and solar.

    In this study, the use of commercial poly(vinyl alcohol) (PVA) as a solid polymer

    electrolyte for use in lithium-ion batteries has been evaluated. Films were prepared

    using various lithium salts such as lithium bis(trifluoromethane)sulfonimide (LiTFSI)

    and casting techniques. Solvent free films were produced by substituting the solvent

    Dimethyl sulfoxide (DMSO) with water and rigouros drying or by employing a

    hot-pressing technique. The best performing system studied was PVA-LiTFSI-DMSO,

    which reached ionic conductivities of 4.5E-5 S/cm at room temperature and 0.45

    mS/cm at 60 °C. The solvent free films showed a drop of ionic conductivity by

    roughly one order of magnitude compared to films with residual DMSO present. High

    ionic conductivities in PVA-LiTFSI-DMSO electrolytes are thus ascribed to fast lithium

    ion transport through the liquid domain of DMSO, or by plasticizing effects of salt and

    solvent on the polymer.

    Thermal analysis of the films showed a clear plasticizing effect of DMSO by a decrease

    in the glass transition temperature. FTIR analysis showed complexation of all the

    lithium salts investigated with the OH-groups of the polymer by a shift in the

    characteristic frequencies of both salts and polymer.

    For the first time, prototype battery cells containing PVA electrolytes were

    manufactured and evaluated by galvanostatic cycling. PVA-LiTFSI-DMSO showed

    stable cycling performance for 15 cycles. Solvent free electrolytes were also

    investigated but did not result in any stable cycling performance.

    Download full text (pdf)
    fulltext
  • 211.
    Ekström, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Förutsättningar för ökad livslängd av sandlåsöverhettare2018Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Superheaters suffer large material loss during combustion of waste and biomass, causing a short life time for these expensive components. During combustion, corrosive ash particles are formed and erosion is caused by circulating bed material and sand particles, all contributing to the material loss. This study examines whether corrosion or erosion has the largest effect on this material loss by investigating two superheaters in loop seal during biomass and waste combustion of an 85 MW, Circulating Fluidized Bed (CFB) boiler in Händelö.

    The samples were investigated by SEM/EDX and XRD with regard to material loss and corrosion products. The superheaters have different thermal conditions since the material temperature in the first superheater that the steam passes is lower than in the one that comes after. In this report, a model to determine the tube temperature in steam boiler superheaters is also described due to the fact that the local tube temperature is of great importance of condensation of corrosive gases such as KCl and NaCl.

    Material loss was significantly greater on the cooler superheater compared with the warmer. The material temperatures on the outside of the tubes, were calculated to be about 574 °C for the cooler superheater and about 617°C for the warmer superheater. Overall, all analyzes showed low levels of corrosive substances, although there was a certain corrosion tendency, which indicates that material loss of the superheaters is caused by corrosion-assisted erosion. Lower material temperature of the superheater resulted in a higher degree of condensation of corrosive species such as alkali chlorides, which might have accelerated the erosion.

    The conclusion is that the dominant mechanism of material loss on the superheaters is erosion. 

  • 212.
    Emera, Flory
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Method development for copper dispersion evaluation and copper-based catalysts characterization2013Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    N2O chemisorption technique for copper dispersion determination was developed and optimized for accurate and reproducible results. With this technique, the bulk oxidation of pre-reduced catalyst can be prevented by N2O decomposition at low temperature (30oC). Only surface copper atoms are oxidized. The amount of freshly oxidized surface coppers is determined from H2-back-titration of fixed oxygen.The impact of temperature and time of exposure during oxidation was studied. Measurements made at higher temperature (60oC) resulted in overestimation of copper dispersion due to oxygen diffusion into the bulk and sub-layers. Much longer exposure time may also have an impact on copper dispersion estimation.For accurate results and good precision, it is recommended to work under mild conditions (isothermal oxidation at 30oC for 45 min.The developed method was successfully applied to fresh and spent catalyst. As expected, the copper dispersion for fresh catalyst was significantly higher than copper dispersion for spent catalyst.

  • 213.
    Engelbrecht, Leon
    et al.
    Stellenbosch Univ, Dept Chem & Polymer Sci, Private Bag X1, ZA-7602 Matieland, South Africa;Univ Cagliari, Dept Chem & Geol Sci, I-09042 Monserrato, Italy;Stockholm Univ, Div Phys Chem, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden.
    Mocci, Francesca
    Univ Cagliari, Dept Chem & Geol Sci, I-09042 Monserrato, Italy.
    Laaksonen, Aatto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Stockholm Univ, Div Phys Chem, Dept Mat & Environm Chem, Arrhenius Lab, S-10691 Stockholm, Sweden;Petru Poni Inst Macromol Chem, Ctr Adv Res Bionanoconjugates & Biopolymers Dept, Aleea Grigore Ghica Voda 41A, Iasi 700487, Romania.
    Koch, Klaus R.
    Stellenbosch Univ, Dept Chem & Polymer Sci, Private Bag X1, ZA-7602 Matieland, South Africa.
    Pt-195 NMR and Molecular Dynamics Simulation Study of the Solvation of [PtCl6](2-) in Water-Methanol and Water-Dimethoxyethane Binary Mixtures2018In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, no 19, p. 12025-12037Article in journal (Refereed)
    Abstract [en]

    The experimental Pt-195 NMR chemical shift, delta((195) Pt), of the [PtCl6](2-) anion dissolved in binary mixtures of water and a fully miscible organic solvent is extremely sensitive to the composition of the mixture at room temperature. Significantly nonlinear delta(Pt-195) trends as a function of solvent composition are observed in mixtures of water-methanol, or ethylene glycol, 2methoxyethanol, and 1,2-dimethoxyethane (DME). The extent of the deviation from linearity of the delta((195) Pt) trend depends strongly on the nature of the organic component in these solutions, which broadly suggests preferential solvation of the [PtCl6](2-) anion by the organic molecule. This simplistic interpretation is based on an accepted view pertaining to monovalent cations in similar binary solvent mixtures. To elucidate these phenomena in detail, classical molecular dynamics computer simulations were performed for [PtCl6](2-) in water-methanol and water-DME mixtures using the anionic charge scaling approach to account for the effect of electronic dielectric screening. Our simulations suggest that the simplistic model of preferential solvation of [PtCl6](2-) by the organic component as inferred from nonlinear delta(Pt-195) trends is not entirely accurate, particularly for water-DME mixtures. The delta(Pt-195) trend in these mixtures levels off for high DME mole fractions, which results from apparent preferential location of [PtCl6](2-) anions at the borders of water-rich regions or clusters within these inherently micro-heterogeneous mixtures. By contrast in water-methanol mixtures, apparently less pronounced mixed solvent micro-heterogeneity is found, suggesting the experimental delta(Pt-195) trend is consistent with a more moderate preferential solvation of [PtCl6](2-) anions. This finding underlines the important role of solvent-solvent interactions and micro-heterogeneity in determining the solvation environment of [PtCl6](2-) anions in binary solvent mixtures, probed by highly sensitive Pt-195 NMR. The notion that preferential solvation of [PtCl6](2-) results primarily from competing ion-solvent interactions as generally assumed for monatomic ions, may not be appropriate in general.

  • 214.
    Eriksson, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Structural Changes in Lithium Battery Materials Induced by Aging or Usage2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Li-ion batteries have a huge potential for use in electrification of the transportation sector. The major challenge to be met is the limited energy storage capacity of the battery pack: both the amount of energy which can be stored within the space available in the vehicle (defining its range), and the aging of the individual battery cells (determining how long a whole pack can deliver sufficient energy and power to drive the vehicle). This thesis aims to increase our knowledge and understanding of structural changes induced by aging and usage of the Li-ion battery materials involved.

    Aging processes have been studied in commercial-size Li-ion cells with two different chemistries. LiFePO4/graphite cells were aged under different conditions, and thereafter examined at different points along the electrodes by post mortem characterisation using SEM, XPS, XRD and electrochemical characterization in half-cells. The results revealed large differences in degradation behaviour under different aging conditions and in different regions of the same cell. The aging of LiMn2O4-LiCoO2/Li4Ti5O12 cells was studied under two different aging conditions. Post mortem analysis revealed a high degree of Mn/Co mixing within individual particles of the LiMn2O4-LiCoO2 composite electrode.

    Structural changes induced by lithium insertion were studied in two negative electrode materials: in Li0.5Ni0.25TiOPO4 using in situ XRD, and in Ni0.5TiOPO4 using EXAFS, XANES and HAXPES. It was shown that Li0.5Ni0.25TiOPO4 lost most of its long-range-order during lithiation, and that both Ni and Ti were involved in the charge compensation mechanism during lithiation/delithiation of Ni0.5TiOPO4, with small clusters of metal-like Ni forming during lithiation.

    Finally, in situ XRD studies were also made of the reaction pathways to form LiFeSO4F from two sets of reactants: either FeSO4·H2O and LiF, or Li2SO4 and FeF2. During the heat treatment, Li2SO4 and FeF2 react to form FeSO4·H2O and LiF in a first step. In a second step LiFeSO4F is formed. This underlines the importance of the structural similarities between LiFeSO4F and FeSO4·H2O in the formation process of LiFeSO4F.

    List of papers
    1. Analysis of aging of commercial composite metal oxide - Li4Ti5O12 battery cells
    Open this publication in new window or tab >>Analysis of aging of commercial composite metal oxide - Li4Ti5O12 battery cells
    Show others...
    2014 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 270, p. 131-141Article in journal (Refereed) Published
    Abstract [en]

    Commercial battery cells with Li4Ti5O12 negative electrode and composite metal oxide positive electrode have been analyzed with respect to aging mechanisms. Electrochemical impedance spectroscopy (EIS), differential capacity analysis (dQ/dV), differential voltage analysis (dV/dQ) and scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX) were used to identify different ageing mechanisms such as lithium inventory loss, loss of active electrode material and surface film growth. The active material of the positive electrode was also examined by X-ray diffraction (XRD). Aging mechanisms were studied for both calendar-aged and cycle-aged cells. Data from half cells prepared from post mortem harvested electrode material, using lithium foil as negative electrode and pouch material as encapsulation, were used as reference to full cell data. Electrochemical analysis of full and half cells combined with material analysis showed to be a powerful method to identify aging mechanisms in this type of commercial cells. The calendar-aged cell showed insignificant aging while the cycle-aged cell showed noticeable loss of positive electrode active material and loss of cyclable lithium, but only minor loss of negative electrode active material. The results imply that Li4Ti5O12 negative electrode material is a good alternative to other materials if high energy density is not the primary goal.

    Keywords
    Hybrid electrical vehicle (HEV), Lithium ion battery, Li4Ti5O12, LiMn2O4, dV/dQ, dQ/dV
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-235294 (URN)10.1016/j.jpowsour.2014.07.050 (DOI)000342245400017 ()
    Available from: 2014-11-11 Created: 2014-10-30 Last updated: 2017-12-05Bibliographically approved
    2. Non-uniform aging of cycled commercial LiFePO4//graphite cylindrical cells revealed by post-mortem analysis
    Open this publication in new window or tab >>Non-uniform aging of cycled commercial LiFePO4//graphite cylindrical cells revealed by post-mortem analysis
    Show others...
    2014 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 257, p. 126-137Article in journal (Refereed) Published
    Abstract [en]

    Aging of power-optimized commercial 2.3 Ah cylindrical LiFePO4//graphite cells to be used in hybrid electric vehicle is investigated and compared for three different aging procedures; (i) using a simulated hybrid electric vehicle cycle within a narrow SOC-range, (ii) using a constant-current cycle over a 100% SOC-range, and (iii) stored during three years at 22 degrees C. Postmortem analysis of the cells is performed after full-cell electrochemical characterization and discharge. EIS and capacity measurements are made on different parts of the disassembled cells. Material characterization includes SEM, EDX, HAXPES/XPS and XRD. The most remarkable result is that both cycled cells displayed highly uneven aging primarily of the graphite electrodes, showing large differences between the central parts of the jellyroll compared to the outer parts. The aging variations are identified as differences in capacity and impedance of the graphite electrode, associated with different SEI characteristics. Loss of cyclable lithium is mirrored by a varying degree of lithiation in the positive electrode and electrode slippage. The spatial variation in negative electrode degradation and utilization observed is most likely connected to gradients in temperature and pressure, that can give rise to current density and potential distributions within the jellyroll during cycling.

    Keywords
    Battery aging, LiFePO4/graphite cells, Hybrid electric vehicle, Synchrotron material characterization, Electrode utilization
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-224557 (URN)10.1016/j.jpowsour.2014.01.105 (DOI)000333780000017 ()
    Funder
    Swedish Energy Agency
    Available from: 2014-05-19 Created: 2014-05-14 Last updated: 2017-12-30
    3. Electrochemical lithium ion intercalation in Li 0.5Ni 0.25TiOPO 4 examined by in situ X-ray diffraction
    Open this publication in new window or tab >>Electrochemical lithium ion intercalation in Li 0.5Ni 0.25TiOPO 4 examined by in situ X-ray diffraction
    Show others...
    2012 (English)In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 225, no SI, p. 547-550Article in journal, Meeting abstract (Refereed) Published
    Abstract [en]

    The complex structural transformations of Li 0.5Ni 0.25TiOPO 4 during electrochemical lithiation have been examined by in situ X-ray diffraction. During the first lithiation two structural changes take place: first a transition to a second monoclinic phase (a = 9.085(4), b = 8.414(5), c = 6.886(5), β = 99.85(4)) and secondly a transition to a third phase with limited long-range order. The third phase is held together by a network of corner sharing Ti-O octahedra and phosphate ions with disordered Ni-Li channels. During delithiation the third phase is partially transformed back to a slightly disordered original phase, Li 0.5Ni 0.25TiOPO 4 without formation of the second intermediate phase. These phase transitions correspond well to the different voltage plateaus that this material shows during electrochemical cycling.

    Keywords
    Batteries, In situ X-ray powder diffraction, Lithium intercalation compounds, Corner sharing, De-lithiation, Electrochemical cycling, Electrochemical lithiation, In-situ, Intermediate phase, Lithiation, Lithium Intercalation, Lithium ions, Long range orders, Monoclinic phase, Phosphate ions, Structural change, Structural transformation, Third phase, Solar cells, X ray diffraction, X ray powder diffraction, Lithium
    National Category
    Natural Sciences Inorganic Chemistry
    Research subject
    Chemistry with specialization in Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-186837 (URN)10.1016/j.ssi.2011.11.001 (DOI)000311873400113 ()
    Conference
    18th International Conference on Solid State Ionics, July 3 -8, 2011, Warsaw, Poland
    Funder
    StandUp
    Available from: 2012-12-06 Created: 2012-11-29 Last updated: 2017-12-30
    4. Electronic and Structural Changes in Ni0.5TiOPO4 Li-ion Battery Cells Upon First Lithiation and Delithiation, Studied by High-Energy X-ray Spectroscopies
    Open this publication in new window or tab >>Electronic and Structural Changes in Ni0.5TiOPO4 Li-ion Battery Cells Upon First Lithiation and Delithiation, Studied by High-Energy X-ray Spectroscopies
    Show others...
    2015 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 18, p. 9692-9704Article in journal (Refereed) Published
    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-243325 (URN)10.1021/jp511170m (DOI)000354339000002 ()
    Funder
    StandUp
    Available from: 2015-02-08 Created: 2015-02-08 Last updated: 2017-12-30
    5. Formation of Tavorite-Type LiFeSO4F Followed by In Situ X-ray Diffraction
    Open this publication in new window or tab >>Formation of Tavorite-Type LiFeSO4F Followed by In Situ X-ray Diffraction
    Show others...
    2015 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 298, p. 363-368Article in journal (Refereed) Published
    Abstract [en]

    The tavorite-type polymorph of LiFeSO4F has recently attracted substantial attention as a positive elec- trode material for lithium ion batteries. The synthesis of this material is generally considered to rely on a topotactic exchange of water (H2O) for lithium (Li) and fluorine (F) within the structurally similar hy- drated iron sulfate precursor (FeSO4·H2O) when reacted with lithium fluoride (LiF). However, there have also been discussions in the literature regarding the possibility of a non-topotactic reaction mechanism between lithium sulfate (Li2SO4) and iron fluoride (FeF2) in tetraethylene glycol (TEG) as reaction medium. In this work, we use in situ X-ray diffraction to continuously follow the formation of LiFeSO4F from the two suggested precursor mixtures in a setup aimed to mimic the conditions of a solvothermal autoclave synthesis. It is demonstrated that LiFeSO4F is formed directly from FeSO4·H2O and LiF, in agreement with the proposed topotactic mechanism. The Li2SO4 and FeF2 precursors, on the other hand, are shown to rapidly transform into FeSO4·H2O and LiF with the water originating from the highly hygroscopic TEG before a subsequent formation of LiFeSO4F is initiated. The results highlight the importance of the FeSO4·H2O precursor in obtaining the tavorite-type LiFeSO4F, as it is observed in both reaction routes.

    National Category
    Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-243324 (URN)10.1016/j.jpowsour.2015.08.062 (DOI)000362146800044 ()
    Funder
    VINNOVA, P37446-1Swedish Energy Agency, 30769-2Swedish Research Council, C0468101StandUp
    Available from: 2015-02-08 Created: 2015-02-08 Last updated: 2017-12-30
    Download full text (pdf)
    fulltext
    Download (jpg)
    presentationsbild
  • 215.
    Eriksson, Rickard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lasri, Karima
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Electronic and Structural Changes in Ni0.5TiOPO4 Li-ion Battery Cells Upon First Lithiation and Delithiation, Studied by High-Energy X-ray Spectroscopies2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 18, p. 9692-9704Article in journal (Refereed)
  • 216.
    Eriksson, Rickard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maher, Kenza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Mansori, Mohammed
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemical lithium ion intercalation in Li 0.5Ni 0.25TiOPO 4 examined by in situ X-ray diffraction2012In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 225, no SI, p. 547-550Article in journal (Refereed)
    Abstract [en]

    The complex structural transformations of Li 0.5Ni 0.25TiOPO 4 during electrochemical lithiation have been examined by in situ X-ray diffraction. During the first lithiation two structural changes take place: first a transition to a second monoclinic phase (a = 9.085(4), b = 8.414(5), c = 6.886(5), β = 99.85(4)) and secondly a transition to a third phase with limited long-range order. The third phase is held together by a network of corner sharing Ti-O octahedra and phosphate ions with disordered Ni-Li channels. During delithiation the third phase is partially transformed back to a slightly disordered original phase, Li 0.5Ni 0.25TiOPO 4 without formation of the second intermediate phase. These phase transitions correspond well to the different voltage plateaus that this material shows during electrochemical cycling.

  • 217.
    Eriksson, Rickard
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sobkowiak, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Formation of Tavorite-Type LiFeSO4F Followed by In Situ X-ray Diffraction2015In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 298, p. 363-368Article in journal (Refereed)
    Abstract [en]

    The tavorite-type polymorph of LiFeSO4F has recently attracted substantial attention as a positive elec- trode material for lithium ion batteries. The synthesis of this material is generally considered to rely on a topotactic exchange of water (H2O) for lithium (Li) and fluorine (F) within the structurally similar hy- drated iron sulfate precursor (FeSO4·H2O) when reacted with lithium fluoride (LiF). However, there have also been discussions in the literature regarding the possibility of a non-topotactic reaction mechanism between lithium sulfate (Li2SO4) and iron fluoride (FeF2) in tetraethylene glycol (TEG) as reaction medium. In this work, we use in situ X-ray diffraction to continuously follow the formation of LiFeSO4F from the two suggested precursor mixtures in a setup aimed to mimic the conditions of a solvothermal autoclave synthesis. It is demonstrated that LiFeSO4F is formed directly from FeSO4·H2O and LiF, in agreement with the proposed topotactic mechanism. The Li2SO4 and FeF2 precursors, on the other hand, are shown to rapidly transform into FeSO4·H2O and LiF with the water originating from the highly hygroscopic TEG before a subsequent formation of LiFeSO4F is initiated. The results highlight the importance of the FeSO4·H2O precursor in obtaining the tavorite-type LiFeSO4F, as it is observed in both reaction routes.

  • 218.
    Eriksson, Susanna K
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Kahk, Juhan Matthias
    Villar-Garcia, Ignacio J
    Webb, Matthew J
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Grennberg, Helena
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Physical Organic Chemistry.
    Yakimova, Rositza
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Edwards, Mårten O M
    Karlsson, Patrik G
    Backlund, Klas
    Ahlund, John
    Payne, David J
    A versatile photoelectron spectrometer for pressures up to 30 mbar2014In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 85, no 7, p. 075119-Article in journal (Refereed)
    Abstract [en]

    High-pressure photoelectron spectroscopy is a rapidly developing technique with applications in a wide range of fields ranging from fundamental surface science and catalysis to energy materials, environmental science, and biology. At present the majority of the high-pressure photoelectron spectrometers are situated at synchrotron end stations, but recently a small number of laboratory-based setups have also emerged. In this paper we discuss the design and performance of a new laboratory based high pressure photoelectron spectrometer equipped with an Al Kα X-ray anode and a hemispherical electron energy analyzer combined with a differentially pumped electrostatic lens. The instrument is demonstrated to be capable of measuring core level spectra at pressures up to 30 mbar. Moreover, valence band spectra of a silver sample as well as a carbon-coated surface (graphene) recorded under a 2 mbar nitrogen atmosphere are presented, demonstrating the versatility of this laboratory-based spectrometer.

  • 219.
    Eriksson, Therese
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Amber, Mace
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Manabe, Yumehiro
    Hokkaido Univ, Fac Engn, Div Appl Chem, Sapporo, Hokkaido 0608628, Japan.
    Yoshizawa-Fujita, Masahiro
    Sophia Univ, Dept Mat & Life Sci, Chiyoda Ku, Tokyo 1028554, Japan.
    Inokuma, Yasuhide
    Hokkaido Univ, Fac Engn, Div Appl Chem, Sapporo, Hokkaido 0608628, Japan.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Polyketones as Host Materials for Solid Polymer Electrolytes2020In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 167, no 7, article id 070537Article in journal (Refereed)
    Abstract [en]

    While solid polymer electrolytes (SPEs) have great potential for use in future lithium-based batteries, they do, however, not display conductivity at a sufficient level as compared to liquid electrolytes. To reach the needed requirements of lithium batteries it is therefore necessary to explore new materials classes to serve as novel polymer hosts. In this work, SPEs based on the polyketone poly(3,3-dimethylpentane-2,4-dione) were investigated. Polyketones are structurally similar to several polycarbonate and polyester SPE hosts investigated before but have, due to the lack of additional oxygen atoms in the coordinating motif, even more electronwithdrawing carbonyl groups and could therefore display better properties for coordination to the salt cation. In electrolyte compositions comprising 25-40 wt% LiTFSI salt, it was observed that this polyketone indeed conducts lithium ions with a high cation transference number, but that the ionic conductivity is limited by the semi-crystallinity of the polymer matrix. The crystallinity decreases with increasing salt content, and a fully amorphous SPE can be produced at 40 wt% salt, accompanied by an ionic conductivity of 3 x 10(-7) S cm(-1) at 32 degrees C. This opens up for further exploration of polyketone systems for SPE-based batteries. 

    Download full text (pdf)
    fulltext
  • 220.
    Eriksson, Therese
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yue, Ma
    Northwestern Polytech Univ, Ctr Nano Energy Mat, Sch Mat Sci & Engn, Youyi West Rd 127, Xian, Shaanxi, Peoples R China.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Effects of nanoparticle addition to poly(epsilon-caprolactone) electrolytes: Crystallinity, conductivity and ambient temperature battery cycling2019In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 300, p. 489-496Article in journal (Refereed)
    Abstract [en]

    It has previously been shown that nanoparticle additives can, in a simple way, significantly improve the ionic conductivity in solid polymer electrolyte systems with the semi-crystalline poly(ethylene oxide) (PEO) as a host material. It has been suggested that the improved ionic conductivity is a result of reduced degree of crystallinity and additional conductivity mechanisms occurring in the material. In this work, this principle is applied to another semi-crystalline polymer host: poly(epsilon-caprolactone) (PCL). This is a polymer with comparable properties (T-g, T-m, etc.) as PEO, and constitute a promising material for use in solid polymer electrolytes for lithium ion batteries. 15 wt% of the respective nanoparticles TiO2, Al2O3 and h-BN have been added to the PCL-LiTFSI solid polymer electrolyte in an attempt to increase the conductivity and achieve stable room temperature cyclability. The crystallinity, ionic conductivity and electrochemical properties were investigated by differential scanning calorimetry, electrochemical impedance spectroscopy and galvanostatic cycling of cells. The results showed that with an addition of 15 wt% Al2O3, the degree of crystallinity is reduced to 6-7% and the ionic conductivity increased to 6-7 x 10(-6) S cm(-1) at room temperature, allowing successful cycling of cells at 30 degrees C, while h-BN did not contribute to similar improvements. The effect of nanoparticles, however, differ significantly from previous observations in PEO systems, which could be explained by different surface-polymer interactions or the degree of ordering in the amorphous phases of the materials.

  • 221.
    Eriksson, Therese
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yue, Ma
    School of Materials Science and Engineering, Center for Nano Energy materials, Northwestern Polytechnical University, Youyi west road 127, Xi'an, China.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nanoparticle Additives in Poly(ε-Caprolactone)-Based Solid PolymerElectrolytes; Towards Lower Crystallinity and Higher Ionic Conductivity.2018Conference paper (Refereed)
  • 222.
    Ershadi, Mahshid
    et al.
    Amirkabir Univ Technol, Dept Chem, Tehran, Iran;Amirkabir Univ Technol, Renewable Energy Res Ctr, Tehran, Iran.
    Javanbakht, Mehran
    Amirkabir Univ Technol, Dept Chem, Tehran, Iran;Amirkabir Univ Technol, Renewable Energy Res Ctr, Tehran, Iran.
    Mozaffari, Sayed Ahmad
    Amirkabir Univ Technol, Renewable Energy Res Ctr, Tehran, Iran;IROST, Dept Chem Technol, Tehran, Iran.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lee, Ming-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zahiri, Beniamin
    Univ British Columbia, Clean Energy Res Ctr, 6250 Appl Sci Lane, Vancouver, BC V6T 1Z4, Canada.
    Facile stitching of graphene oxide nanosheets with ethylenediamine as three dimensional anode material for lithium-ion battery2020In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 818, article id 152912Article in journal (Refereed)
    Abstract [en]

    In this study, we employed an efficient and straightforward synthesis method for the functionalization and stitching of graphene oxide (GO) sheets with ethylenediamine (EDA). 3-D-structured GO-EDA was prepared by low reduction of the oxygen-containing functional groups of GO. The EDA was used as a nitrogen source to create the nitrogen-doped graphene (N-graphene), as well as a factor to control the self-assembly of graphene nanosheets into 3-D structures. The morphology, composition, and covalently grafted functional groups of GO-EDA were investigated by FT-IR and Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and various electrochemical techniques. GO-EDA exhibits a layered structure resembling graphite, with an enhanced d-spacing of 0.373 nm compared with graphite (0.348 nm). The results showed that the porous channels of the synthesized GO-EDA facilitate the efficient transportation of lithium ions through the electrolyte-filled channels. The first discharge and charge showed specific capacities of 830.34 mAh g(-1) and 664 mAh g(-1), respectively at the current density of 100 mA g(-1), corresponding to an initial coulombic efficiency of ca. similar to 80%; superior to the GO reference (27.8%). Moreover, GO-EDA displayed improve cycling stability (maintaining a reversible capacity of similar to 300 mAh g(-1) at 200 mA g(-1) after 100 cycles). The improved electrochemical operation was ascribed to enhanced ion (Li+) transport within the graphitic layers by the increased d-spacing due to the inserted functional groups. 

  • 223.
    Etman, Ahmed
    et al.
    Stockholm University.
    Inge, Ken
    Stockholm University.
    Jiaru, Xu
    Peking University.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Junliang
    Stockholm University, Peking University.
    A Water Based Synthesis of Ultrathin Hydrated Vanadium Pentoxide Nanosheets for Lithium Battery Application: Free Standing Electrodes or Conventionally Casted Electrodes?2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 252, p. 254-260Article in journal (Refereed)
    Abstract [en]

    Abstract: Ultrathin hydrated vanadium pentoxide (V2O5·nH2O) nanosheets are fabricated via a water based exfoliation technique. The exfoliation process involves reflux of the precursor, 1:4 mixture of VO2 and V2O5, in water at 80 °C for 24 h. Operando and ex situ X-ray diffraction (XRD) studies are conducted to follow the structural changes during the exfoliation process. The chemical and thermal analyses suggest that the molecular formula of the nanosheet is H 0.2 V 1.8 V V 0.2 IV O 5 ⋅ 0.5 H 2 O . The V2O5·nH2O nanosheets are mixed with 10% of multi-walled carbon nanotube (MW-CNT) to form a composite material assigned as (VOx-CNT). Free standing electrodes (FSE) and conventionally casted electrodes (CCE) of VOx-CNT are fabricated and then tested as a positive electrode material for lithium batteries. The FSE shows reversible capacities of 300 and 97 mAhg-1 at current densities of 10 and 200 mAhg-1, respectively. This is better than earlier reports for free-standing electrodes. The CCE delivers discharge capacities of 175 and 93 mAhg-1 at current densities of 10 and 200 mAhg-1, respectively.

  • 224.
    Etman, Ahmed S.
    et al.
    Stockholms Universitet.
    Asfaw, Habtom D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yuan, Ning
    Stockholm University and SLU.
    Li, Jian
    Peking University, China.
    Zhou, Zhengyang
    Peking University.
    Peng, Fei
    Stockholm University.
    Persson, Ingmar
    Swedish University of Agricultural Sciences.
    Zou, Xiaodong
    Stockholm University.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Junliang
    Stockholm University and Peking University.
    A one-step water based strategy for synthesizing hydrated vanadium pentoxide nanosheets from VO2(B) as free-standing electrodes for lithium battery applications2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 46, p. 17988-18001Article in journal (Refereed)
    Abstract [en]

    The synthesis of two dimensional (2D) materials from transition metal oxides, chalcogenides, and carbides mostly involve multiple exfoliation steps in which hazardous solvents and reagents are used. In this study, hydrated vanadium pentoxide (V2O5[middle dot]nH2O) nanosheets with a thickness of a few nanometers were prepared via a facile environmentally friendly water based exfoliation technique. The exfoliation process involved refluxing the precursor, vanadium dioxide (VO2(B)), in water for a few days at 60 [degree]C. The proposed exfoliation mechanism is based on the intercalation/insertion of water molecules into the VO2(B) crystals and the subsequent cleavage of the covalent bonds holding the layers of VO2(B) together. The thermal and chemical analyses showed that the approximate chemical composition of the nanosheets is H0.4V2O5[middle dot]0.55H2O, and the percentage of VV content to that of VIV in the nanosheets is about 80(3)% to 20(3)%. The exfoliated aqueous suspension of the V2O5[middle dot]0.55H2O nanosheets was successfully deposited onto multi-walled carbon nanotube (MW-CNT) paper to form free-standing electrodes with a thickness of the V2O5[middle dot]0.55H2O layer ranging between 45 and 4 [small mu ]m. A series of electrochemical tests were conducted on the electrodes to determine the cyclability and rate capability of lithium insertion into V2O5[middle dot]0.55H2O nanosheets. The electrodes with the thinnest active material coating ([similar]4 [small mu ]m) delivered gravimetric capacities of up to 480 and 280 mA h g-1 when cycled at current densities of 10 and 200 mA g-1, respectively.

  • 225.
    Etman, Ahmed S.
    et al.
    Berzelii Center EXSELENT on Porous Materials, Department of Material and Environmental Chemistry (MMK), Stockholm University, Sweden.
    Inge, Andrew Kentaro
    Berzelii Center EXSELENT on Porous Materials, Department of Material and Environmental Chemistry (MMK), Stockholm University, Sweden.
    Jiaru, Xu
    College of Chemistry and Molecular Engineering, Peking University, China.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Junliang
    Berzelii Center EXSELENT on Porous Materials, Department of Material and Environmental Chemistry (MMK), Stockholm University, Sweden; College of Chemistry and Molecular Engineering, Peking University, China.
    Simple and Green Method for Fabricating V2O5·nH2O Nanosheets for Lithium Battery Application2017Conference paper (Other academic)
    Abstract [en]

    During the last few years, the synthesis of inorganic two dimensional (2D) materials tremendously increased, due to their promising surface area1,2. However, the synthesis of these 2D materials can significantly influence our environment, by the use of harmful chemicals and severe reaction conditions3,4.

    Herein, we report on a simple and green strategy for fabricating hydrated vanadium pentoxide (V2O5.nH2O) nanosheets from commercially available vanadium oxides precursors via water based exfoliation technique. Operando and ex situ X-ray diffraction (XRD) studies were conducted to track the structural changes during the exfoliation process. The vanadium oxidation states and the water content of the material were determined by X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA), respectively. Electron microscopy and atomic force microscopy (AFM) showed that the V2O5.nH2O is composed of a few nanometer thick nanosheets. A composite material of the V2O5∙nH2O nanosheets and multi-walled carbon nanotube (MW-CNT) were fabricated and then tested as a free standing electrodes (FSE) and conventionally casted electrodes (CCE) for lithium battery. Both electrodes showed promising capacities and rate capabilities for lithium-ion intercalation.

    References:

    (1) Nicolosi, V.; Chhowalla, M.; Kanatzidis, M. G.; Strano, M. S.; Coleman, J. N. Liquid Exfoliation of Layered Materials. Science (80-. ). 2013, 340 (6139), 1226419.

    (2) Etman, A. S.; Asfaw, H. D.; Yuan, N.; Li, J.; Zhou, Z.; Peng, F.; Persson, I.; Zou, X.; Gustafsson, T.; Edström, K.; Sun, J. A One-Step Water Based Strategy for Synthesizing Hydrated Vanadium Pentoxide Nanosheets from VO2 (B) as Free-Standing Electrodes for Lithium Battery Applications. J. Mater. Chem. A 2016, 4 (46), 17988–18001.

    (3) Wei, Q.; Liu, J.; Feng, W.; Sheng, J.; Tian, X.; He, L.; An, Q.; Mai, L. Hydrated Vanadium Pentoxide with Superior Sodium Storage Capacity. J. Mater. Chem. A 2015, 3, 8070–8075.

    (4) Zhou, K.-G.; Mao, N.-N.; Wang, H.-X.; Peng, Y.; Zhang, H.-L. A Mixed-Solvent Strategy for Efficient Exfoliation of Inorganic Graphene Analogues. Angew. Chem. Int. Ed. Engl. 2011, 50 (46), 10839–10842.

    Download full text (pdf)
    fulltext
  • 226.
    Etman, Ahmed S
    et al.
    Stockholm University.
    Wang, Ligang
    Peking University.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Junliang
    Stockholm University.
    Molybdenum Oxide Nanosheets with Tunable Plasmonic Resonance: Aqueous Exfoliation Synthesis and Charge Storage Applications2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 29, no 4, article id 1806699Article in journal (Refereed)
    Abstract [en]

    Herein, a simple aqueous-exfoliation strategy is introduced for the fabrication of a series of MoO3−x nanosheets (where x stands for oxygen vacancies) using two commercial molybdenum oxide precursors, MoO2 and MoO3. The nanosheets offer a localized surface plasmon resonance (LSPR) effect which is dependent on the structure and local environment of the nanosheets. The LSPR can be efficiently tuned by changing the weight ratio between the molybdenum oxide precursor(s) and/or by solar light irradiation using a low-energy UV lamp (36 W). For the pristine MoO3−x nanosheets, the highest LSPR signal is obtained for nanosheets prepared using 80% MoO2. On the contrary, after solar light irradiation, the nanosheets prepared using pure MoO3 offer the highest LSPR response. The nanosheets also show an outstanding rate capability when used as binder-free supercapacitor electrodes in an acidified Na2SO4 electrolyte. The electrodes exhibit discharge capacities of 110 and 75 C g−1 at a scan rate of 20 and 1000 mV s−1, respectively. The MoO3−x nanosheets can likewise be used as a negative electrode material for lithium-ion batteries. The efficient eco-friendly synthesis and the ability to tune the photochemical and electrochemical properties of the nanosheets make this approach interesting to many energy-related research fields.

  • 227. Etman, Ahmed
    et al.
    Sun, Junliang
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    V2O5·nH2O nanosheets and multi-walled carbon nanotube composite as a negative electrode for sodium-ion batteries2019In: Journal of Energy Chemistry, ISSN 2095-4956, Vol. 30, p. 145-151Article in journal (Refereed)
    Abstract [en]

    Two dimensional (2D) transition metal oxides and chalcogenides demonstrate a promising performance in sodium-ion batteries (SIBs) application. In this study, we investigated the use of a composite of freeze dried V2O5 center dot nH(2)O nanosheets and multi-walled carbon nanotube (MWCNT) as a negative electrode material for SIBs. Cyclic voltammetry (CV) results indicated that a reversible sodium-ion insertion/deinsertion into the composite electrode can be obtained in the potential window of 0.1-2.5 V vs. Na+/Na. The composite electrodes delivered sodium storage capacities of 140 and 45 mAh g(-1) under applied current densities of 20 and 100 mA g(-1), respectively. The pause test during constant current measurement showed a raise in the open circuit potential (OCP) of about 0.46 V, and a charge capacity loss of similar to 10%. These values are comparable with those reported for hard carbon electrodes. For comparison, electrodes of freeze dried V2O5 center dot nH(2)O nanosheets were prepared and tested for SIBs application. The results showed that the MWCNT plays a significant role in the electrochemical performance of the composite material. 

  • 228.
    Etman, Ahmed
    et al.
    Stockholm University.
    Wang, Ligang
    Peking University.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Junliang
    Stockholm University, Peking University.
    One-pot Synthesis of MoO3-x Nanosheets for Supercapacitor Applications2018Conference paper (Other academic)
    Abstract [en]

    Molybdenum oxide nanosheets are interesting materials for energy storage, catalysis, and gas sensor applications.1 However, they are traditionally prepared via a variety of approaches which require the use of high temperature or organic solvents.2,3 Herein, we report the synthesis of MoO3-x nanosheets (where x denotes oxygen vacancy) via a one-step water based exfoliation strategy using bulk molybdenum oxides precursors.4 Scanning and transmission electron microscopy show that the MoO3-x has a typical nanosheet morphology with a few nanometer thickness. The MoO3-x nanosheets display localized surface plasmon resonance (LSPR), which can be enhanced by modifying the morphology and the amount of oxygen vacancies (x) using chemical and/or photochemical treatments.

    The aqueous suspension of the MoO3-x nanosheets was drop-cast onto carbon paper and this material was then used as binder free electrodes for supercapacitor applications. The electrodes showed promising performance regarding capacitance and rate capability in acidified sodium sulphate solutions. The facile green synthesis of MoO3-x nanosheets coupled with their significant photochemical and electrochemical properties pave the way for the use of the nanosheets in a variety of applications.

    References:

    (1)        de Castro, I. A.; Datta, R. S.; Ou, J. Z.; Castellanos-Gomez, A.; Sriram, S.; Daeneke, T.; Kalantar-zadeh, K. Molybdenum Oxides - From Fundamentals to Functionality. Adv. Mater. 2017, 29 (40), 1701619.

    (2)        Xiao, X.; Song, H.; Lin, S.; Zhou, Y.; Zhan, X.; Hu, Z.; Zhang, Q.; Sun, J.; Yang, B.; Li, T.; Jiao, L.; Zhou, J.; Tang, J.; Gogotsi, Y. Scalable Salt-Templated Synthesis of Two-Dimensional Transition Metal Oxides. Nat. Commun. 2016, 7, 11296.

    (3)        Alsaif, M. M. Y. A.; Field, M. R.; Daeneke, T.; Chrimes, A. F.; Zhang, W.; Carey, B. J.; Berean, K. J.; Walia, S.; van Embden, J.; Zhang, B.; Latham, K.; Kalantar-zadeh, K.; Ou, J. Z. Exfoliation Solvent Dependent Plasmon Resonances in Two-Dimensional Sub-Stoichiometric Molybdenum Oxide Nanoflakes. ACS Appl. Mater. Interfaces 2016, 8 (5), 3482–3493.

    (4)      Etman A. S.; Abdelhamid H. N.; Yuan Y.; Wang L.; Zou X.; Sun J. Facile Water Based Strategy for Synthesizing MoO3-x Nanosheets: Efficient Visible Light Photocatalyst for Dye Degradation. ACS Omega. in Press.

  • 229.
    Fang, Hailiang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Li, Jiheng
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Univ Sci & Technol Beijing, State Key Lab Adv Met & Mat, Beijing, Peoples R China.
    Shafeie, Samrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedlund, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Cedervall, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ekström, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gómez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bednarcik, Jozef
    Deutsch Elektronen Synchrotron DESY, Notkestr 85, D-22603 Hamburg, Germany.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Gunnarsson, Klas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Insights into phase transitions and magnetism of MnBi crystals synthesized from self-flux2019In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 781, p. 308-314Article in journal (Refereed)
    Abstract [en]

    To effectively synthesize high purity ferromagnetic low temperature phase (LTP) MnBi with optimal microstructure is still a challenge that needs to be overcome for the system to reach its full potential. Here, the phase transitions and magnetic properties of MnBi crystals are reported. The phase transition between the low and high temperature structure of MnBi was systematically investigated at different heating/cooling rates using in situ synchrotron radiation X-ray diffraction. The material crystallizes in a layered hexagonal structure giving a platelike microstructure. The magnetic characterization of the crystals reveal that the saturation magnetization varies from 645 kA/m at 50 K to 546 kA/m at 300 K. Magnetization measurements also show that the sample upon heating becomes non-magnetic and transforms to the high temperature phase (HTP) at similar to 640 K, and that it regains ferromagnetic properties and transforms back to the LTP at similar to 610 K upon subsequent cooling.

  • 230.
    Farhat, Douaa
    et al.
    Univ Francois Rabelais Tours, France..
    Ghamouss, Fouad
    Univ Francois Rabelais Tours, France..
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lemordant, Daniel
    Univ Francois Rabelais Tours, France..
    Adiponitrile-Lithium Bis(trimethylsulfonyl)imide Solutions as Alkyl Carbonate-free Electrolytes for Li4Ti5O12 (LTO)/LiNi1/3Co1/3Mn1/3O2 (NMC) Li-Ion Batteries2017In: ChemPhysChem, ISSN 1439-4235, E-ISSN 1439-7641, Vol. 18, no 10, p. 1333-1344Article in journal (Refereed)
    Abstract [en]

    Recently, dinitriles (NC(CH2)(n)CN) and especially adiponitrile (ADN, n = 4) have attracted attention as safe electrolyte solvents owing to their chemical stability, high boiling points, high flash points, and low vapor pressure. The good solvation properties of ADN toward lithium salts and its high electrochemical stability (approximate to 6 V vs. Li/Li+) make it suitable for safer Li-ions cells without performance loss. In this study, ADN is used as a single electrolyte solvent with lithium bis(trimethylsulfonyl) imide (LiTFSI). This electrolyte allows the use of aluminium collectors as almost no corrosion occurs at voltages up to 4.2 V. The physicochemical properties of the ADN-LiTFSI electrolyte, such as salt dissolution, conductivity, and viscosity, were determined. The cycling performances of batteries using Li4Ti5O12 (LTO) as the anode and LiNi1/3Co1/3Mn1/3O2 (NMC) as the cathode were determined. The results indicate that LTO/NMC batteries exhibit excellent rate capabilities with a columbic efficiency close to 100 %. As an example, cells were able to reach a capacity of 165 mAhg(-1) at 0.1C and a capacity retention of more than 98% after 200 cycles at 0.5 C. In addition, electrodes analyses by SEM, X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy after cycling confirming minimal surface changes of the electrodes in the studied battery system.

  • 231.
    Farhat, Douaa
    et al.
    Univ Francois Rabelais Tours, UFR Sci & Tech, Lab PCM2E, EA 6296, Parc Grandmont, F-37200 Tours, France.
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Eriksson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lemordant, Daniel
    Univ Francois Rabelais Tours, UFR Sci & Tech, Lab PCM2E, EA 6296, Parc Grandmont, F-37200 Tours, France.
    Ghamouss, Fouad
    Univ Francois Rabelais Tours, UFR Sci & Tech, Lab PCM2E, EA 6296, Parc Grandmont, F-37200 Tours, France.
    Towards high-voltage Li-ion batteries: Reversible cycling of graphite anodes and Li-ion batteries in adiponitrile-based electrolytes2018In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 281, p. 299-311Article in journal (Refereed)
    Abstract [en]

    Due to their low vapor pressure and their promising electrochemical and thermal stability, N C- (CH2)n-C N dinitriles are proposed as an electrolyte solvent for Li-ion batteries. Adiponitrile (ADN) has substantial advantages, especially for applications requiring high potential cathodes, because it has high electrochemical/thermal stability (up to 6 V vs. Li/Li+, > 120 degrees C). However, to obtain very high voltage batteries, ADN electrolytes must also passivate the anode of the battery. In this work, reversible cycling of graphite in adiponitrile was successfully achieved by adding a few percent of fluoroethylene carbonate allowing the realization of Graphite/NMC Li-ion battery. The battery of specific capacity of 135 mAhh.g(-1) showed a cycling stability for more than 40 cycles. The composition of the solid electrolyte interphase (SEI) was determined as a function of the FEC concentration as well as the state of charge of the graphite anode using hard X-ray photoelectron spectroscopy (HAXPES) and XPS. With FEC, the SEI layer is thinner and depends on the SOC of the anode, but does not depend on the FEC concentration. SEM characterizations clearly showed that the surface of the anode is completely covered by the SEI layer, regardless of the concentration of FEC. Indeed, 2% of FEC is sufficient to suppress the reduction of adiponitrile which is explained by a specific adsorption of FEC on the graphite anode.

  • 232. Feng, Feng
    et al.
    Hu, Shuanglin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Guo, Yuqiao
    Zhao, Jiyin
    Chan, Ngai Yui
    Fei, Linfeng
    Yan, Wensheng
    Ning, Wei
    Yang, Jinlong
    Wang, Yu
    Xiea, Yi
    Wu, Changzheng
    Room-temperature large magnetic-dielectric coupling in new phase anatase VTiO42013In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 49, no 89, p. 10462-10464Article in journal (Refereed)
    Abstract [en]

    The synthetic new-phase VTiO4, as a new solid solution structure of anatase type, brings a large magnetodielectric ratio (Delta epsilon/epsilon(0)) of 7.2% at 300 K, representing a new simple-oxide structural catalogue exhibiting a room-temperature large magnetic-dielectric effect.

  • 233. Feng, Jun
    et al.
    Peng, Lele
    Wu, Changzheng
    Sun, Xu
    Hu, Shuanglin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lin, Chenwen
    Dai, Jun
    Yang, Jinlong
    Xie, Yi
    Giant Moisture Responsiveness of VS2 Ultrathin Nanosheets for Novel Touchless Positioning Interface2012In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 24, no 15, p. 1969-1974Article in journal (Refereed)
    Abstract [en]

    Utilizing a thin film of VS2 ultrathin nanosheets with giant and fast moisture responsiveness, a brand-new model of moisture-based positioning interface is put forward here, by which not only the 2D position information of finger tips can be acquired, but also the relative height can be detected as the third dimensionality, representing a promising platform for advanced man-machine interactive systems.

  • 234.
    Flores, Eibar
    et al.
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Novak, Petr
    Paul Scherrer Inst, Electrochem Lab, CH-5232 Villigen, Switzerland.
    Aschauer, Ulrich
    Univ Bern, Dept Chem & Biochem, CH-3012 Bern, Switzerland.
    Berg, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cation Ordering and Redox Chemistry of Layered Ni-Rich LixNi1-2yCoyMnyO2: An Operando Raman Spectroscopy Study2020In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 32, no 1, p. 186-194Article in journal (Refereed)
    Abstract [en]

    Although layered transition metal oxides are state-of-the-art cathode active materials for Li-ion batteries, many fundamental aspects of their operation are poorly understood, in particular, how the local lattice structure and transition metal composition influence their electrochemical activity. In this work, the local structure and redox activity of Ni-rich LixNi1-2yCoyMnyO2 (y = 0.1, 0.2, and 0.33, abbreviated as NCM811, NCM622, and NCM111, respectively) Li-ion cathodes are characterized under standard and overcharge operating conditions with a recently developed operando Raman spectroscopy methodology. Supported by DFT phonon calculations and advanced data analysis methods, we demonstrate that the Raman spectra of NCMs entail spectroscopic signatures of cation ordering phenomena, sequential oxidation/reduction of nickel, and participation of bulk lattice oxygen in the charge-compensation process at a low state of lithiation (SOL). Our methodology enables monitoring such processes during cycling and offers the potential for investigating the mechanisms by which certain strategies (i.e., doping, surface coatings, etc.) ameliorate electrochemical performance.

  • 235.
    Flores, Eibar
    et al.
    Paul Scherrer Inst, Electrochem Lab, Energy & Environm Res Div, Villigen, Switzerland.
    Novak, Petr
    Paul Scherrer Inst, Electrochem Lab, Energy & Environm Res Div, Villigen, Switzerland.
    Jämstorp, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, Energy & Environm Res Div, Villigen, Switzerland.
    In situ and Operando Raman Spectroscopy of Layered Transition Metal Oxides for Li-ion Battery Cathodes2018In: FRONTIERS IN ENERGY RESEARCH, ISSN 2296-598X, Vol. 6, article id 82Article in journal (Refereed)
    Abstract [en]

    In situ and operando Raman spectroscopy is proposed to provide unique means for deeper fundamental understanding and further development of layered transition metal LiMO2 (M = Ni, Co, Mn) oxides suitable for Li-ion battery applications. We compare several spectro-electrochemical cell designs and suggest key experimental parameters for obtaining optimum electrochemical performance and spectral quality. Studies of the most practically relevant LiMO2 compositions are exemplified with particular focus on two experimental approaches: (1) lateral and axial Raman mapping of the electrode's (near-) surface to monitor inhomogeneous electrode reactions and (2) time-dependent single-particle spectra during cycling to analyze the LixMO2 lattice dynamics as a function of lithium content. Raman Spectroscopy is claimed to provide a unique real-time probe of the M-O bonds, which are at the heart of the electrochemistry of LiMO2 oxides and govern their stability. We highlight the need for further fundamental understanding of the relationships between the spectroscopic response and oxide lattice structure with particular emphasis on the development of a theoretical framework linking the position and intensity of the Raman bands to the local LixMO2 lattice con figuration. The use of complementary experimental techniques and model systems for validation also deserve further attention. Several novel LiMO2 compositions are currently being explored, especially containing dopings and coatings, and Raman spectroscopy could offer a highly dynamic and convenient tool to guide the formulation of high specific charge and long cycle life LiMO2 oxides for next-generation Li-ion battery cathodes.

    Download full text (pdf)
    fulltext
  • 236.
    Flores, Eibar
    et al.
    Paul Scherrer Inst, Electrochem Lab, Villigen, Switzerland.
    Vonrüti, Nathalie
    Univ Bern, Dept Chem & Biochem, Bern, Switzerland.
    Novák, Petr
    Paul Scherrer Inst, Electrochem Lab, Villigen, Switzerland.
    Aschauer, Ulrich
    Univ Bern, Dept Chem & Biochem, Bern, Switzerland.
    Berg, Erik Jämstorp
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Paul Scherrer Inst, Electrochem Lab, Villigen, Switzerland.
    Elucidation of LixNi0.8Co0.15Al0.05O2 Redox Chemistry by Operando Raman Spectroscopy2018In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 30, no 14, p. 4694-4703Article in journal (Refereed)
    Abstract [en]

    The local structure evolution of LixNi0.8Co0.15Al0.05O2 (NCA) is linked to its electrochemical response during cycling (and overcharge) by operando Raman spectroscopy with findings supported by complementary techniques, such as online electrochemical mass spectrometry (OEMS) and density functional theory (DFT) phonon calculations. The vibrational motion of lattice oxygens is observed to be highly dependent on the local LixMO2 lattice environment, e.g. M—O bonding strength/length and state of lithiation x. All vibrational modes generally harden upon delithiation due to M—O bond character (ionic → covalent) evolution (disregarding an early bond softening due to Li+ vacancy formation) and evidence the important influence of the local structural lattice configuration on the electrochemical response of NCA. Although the intensities of all Raman active bands generally increase upon delithiation, a major inflection point at x = 0.2 marks the onset of a partly irreversible fundamental transition within NCA that is most likely related to electron removal from MO bonding states and partial oxidation of oxygen sublattice, which is also indicated by the observed concomitant O2 release from the particle surface. Operando Raman spectroscopy with higher time resolution provides unique possibilities for detailed studies of how chemical parameters (Li+ vacancy formation, transition metal cation concentration, and lattice doping, etc.) may govern the onset and nature of processes (such as bond character evolution and stability) that define the performance of the LixMO2 class of oxides. The further insights thus gained can be exploited to guide the development of next-generation layered cathodes for Li-ion batteries operating stably at higher voltages and capacities.

  • 237. Fossépré, Mathieu
    et al.
    Leherte, Laurence
    Laaksonen, Aatto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Vercauteren, Daneil P.
    Understanding the Structure and Dynamics of Peptides and Proteins Through the Lens of Network Science2019In: Biomolecular Simulations in Structure-based Drug Discovery, Wiley-VCH Verlagsgesellschaft, 2019Chapter in book (Refereed)
  • 238.
    Franco, Alejandro A.
    et al.
    Univ Picardie Jules Verne, CNRS, LRCS, Hub Energie,UMR 7314, 15 Rue Baudelocque, F-80039 Amiens 1, France;CNRS, Reseau Stockage Electrochim Energie RS2E, Hub Energie, FR 3459, 15 Rue Baudelocque, F-80039 Amiens 1, France;CNRS, ALISTORE European Res Inst, Hub Energie, FR 3104, 15 Rue Baudelocque, F-80039 Amiens 1, France;Inst Univ France, 103 Blvd St Michel, F-75005 Paris, France.
    Rucci, Alexis
    Univ Picardie Jules Verne, CNRS, LRCS, Hub Energie,UMR 7314, 15 Rue Baudelocque, F-80039 Amiens 1, France;CNRS, Reseau Stockage Electrochim Energie RS2E, Hub Energie, FR 3459, 15 Rue Baudelocque, F-80039 Amiens 1, France.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. CNRS, ALISTORE European Res Inst, Hub Energie, FR 3104, 15 Rue Baudelocque, F-80039 Amiens 1, France.
    Frayret, Christine
    Univ Picardie Jules Verne, CNRS, LRCS, Hub Energie,UMR 7314, 15 Rue Baudelocque, F-80039 Amiens 1, France;CNRS, Reseau Stockage Electrochim Energie RS2E, Hub Energie, FR 3459, 15 Rue Baudelocque, F-80039 Amiens 1, France;CNRS, ALISTORE European Res Inst, Hub Energie, FR 3104, 15 Rue Baudelocque, F-80039 Amiens 1, France.
    Gaberscek, Miran
    CNRS, ALISTORE European Res Inst, Hub Energie, FR 3104, 15 Rue Baudelocque, F-80039 Amiens 1, France;Natl Inst Chem, Dept Mat Chem, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.
    Jankowski, Piotr
    CNRS, ALISTORE European Res Inst, Hub Energie, FR 3104, 15 Rue Baudelocque, F-80039 Amiens 1, France;Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden;Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland.
    Johansson, Patrik
    CNRS, ALISTORE European Res Inst, Hub Energie, FR 3104, 15 Rue Baudelocque, F-80039 Amiens 1, France;Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Boosting Rechargeable Batteries R&D by Multiscale Modeling: Myth or Reality?2019In: Chemical Reviews, ISSN 0009-2665, E-ISSN 1520-6890, Vol. 119, no 7, p. 4569-4627Article, review/survey (Refereed)
    Abstract [en]

    This review addresses concepts, approaches, tools, and outcomes of multiscale modeling used to design and optimize the current and next generation rechargeable battery cells. Different kinds of multiscale models are discussed and demystified with a particular emphasis on methodological aspects. The outcome is compared both to results of other modeling strategies as well as to the vast pool of experimental data available. Finally, the main challenges remaining and future developments are discussed.

    Download full text (pdf)
    fulltext
  • 239.
    Fredriksson, Wendy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    XPS study of duplex stainless steel as a possible current collector in a Li-ion battery2012In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 79, p. 82-94Article in journal (Refereed)
    Abstract [en]

    The surface chemistry and corrosion property of a duplex LDX 2101 steel that had been cycled in a Li-ion battery with a 1 M LiPF6 in EC/DMC 1:1 electrolyte was studied. The results are compared to those of steel stored for the same length of time. Cyclic voltammetry was used to sweep the steel between 0 V and 5 V and the different reduction products were identified with SEM, XRD and XPS. A conversion reaction occurred during the cathodic sweep between 2.0 and 1.5 V where chromium and iron oxides were reduced forming Li2O and metal. At 0.5 V vs. Li+/Li a Solid Electrolyte Interface (SEI) was irreversibly formed predominantly during the first cycle. During the oxidation sweep the typical stainless steel passive layer of chromium and iron oxides/hydroxides formed at 2.5 V vs. Li/Li+. Li2O also decomposed at this potential. Simultaneously metal fluorides are formed. The XPS revealed a thicker SEI containing organic and inorganic species on the cycled electrode than on the stored. The stored sample showed chemical formation of CrF3 on the surface. Depth profiling of the cycled electrode by Ar+ etching showed a thick layer of CrF3 and a thin layer of FeF3. We conclude that the level of corrosion of this duplex steel is acceptable in the 3–4.5 V vs. Li+/Li region. However, in a Li-ion battery it is too reactive at low potentials to be considered as a replacement for copper as an anode current collector. We also observe that the PF6 anion from the electrolyte salt plays an important role in the formation of metal fluorides which is a fact generally neglected in the discussion of conversion reactions of metal-oxide anodes for Li-ion batteries. For stainless steel to be considered as current collectors for Li-ion batteries optimisation of alloy compositions need to be made to reduce corrosion occurring during cycling in organic solvents.

  • 240.
    Fredriksson, Wendy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Olsson, Claes
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    XPS analysis of manganese in stainless steel passive films on 1.4432 and the lean duplex 1.41622010In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 52, no 7, p. 2505-2510Article in journal (Refereed)
    Abstract [en]

    Passive films were compared on two stainless steels: the recent lean duplex EN 1.4162 and EN 1.4432 (316L). For alloys with significant amount of manganese and nickel, the Mn 2p(3/2) peak will overlap with the Ni-LMM. To resolve this overlap, Ni 2p(3/2) to Ni-LMM intensity ratios were recorded on 1.4432, compensated for overlayer thickness, and then used to fix the Ni-LMM intensities in the Mn 2p spectra on the duplex material. Manganese was found in oxidation states II and V/VI: its film content was not dependent on the bulk composition. (C) 2010 Elsevier Ltd. All rights reserved.

  • 241.
    Fredriksson, Wendy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Malmgren, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Full depth profile of passive films on 316L stainless steel based on high resolution HAXPES in combination with ARXPS2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 15, p. 5790-5797Article in journal (Refereed)
    Abstract [en]

    Depth profiles of the passive films on stainless steel were based on analysis with the non-destructive hard X-ray photoelectron spectroscopy (HAXPES) technique in combination with the angular resolved X-ray photoelectron spectroscopy (ARXPS). The analysis depth with ARXPS is within the passive film thickness, while the HAXPES technique uses higher excitation energies (between 2 and 12 keV) also non-destructively probing the chemical content underneath the film. Depth profiles were done within and underneath the passive film of 316L polarized in acidic solution. The passive film thickness was estimated to 2.6 nm for a sample that was polarized at 0.6 V and the main component in the passive film is, as expected, chromium. From the high resolution HAXPES spectra we suggest chromium in three different oxidation states present. Also for iron three oxides were detected. Gradients of chromium and iron concentrations and oxidation states within the film and an enrichment of nickel within a 0.5 nm layer directly underneath the passive film are some of the results discussed. 

  • 242.
    Fredriksson, Wendy
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Petrini, Daniel
    Erasteel Kloster AB, Box 100, Söderfors SE-815 82, Sweden.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Corrosion Resistances and Passivation of Powder Metallurgical and Conventionally Cast 316L and 2205 Stainless Steels2013In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 67, p. 268-280Article in journal (Refereed)
    Abstract [en]

    The corrosion resistances and passivation of austenitic 316L and duplex 2205 powder metallurgical (P/M) steels, produced by employing gas atomizing and hot isostatic pressing (HIP), have been compared with those of their conventional cast and forged counterparts. The P/M 316L steel is shown to have a significantly higher pitting corrosion resistance than the conventional 316L steel in 0.5 M HCl. Since the chemical composition and the total amount of inclusions were analogous for the two steels, the effect is ascribed to the finer grained microstructure for the P/M 316L steel yielding a better passive layer. This is supported by photoelectron spectroscopy data demonstrating differences between the thickness and composition of the passive layers for the two 316 L steels. Differences in the passivation process were also found for the different steels as three mixed potentials were observed in the polarization curves for the P/M and conventional 316L steels whereas only one mixed potential at about +0.7 V vs. Ag/AgCl was observed for the two duplex steels in 0.5 M HCl. The results indicate that discussions of the shapes of polarization curves and mixed potentials should be based on the anodic and cathodic partial currents, including the reduction of oxygen. HIP:ed P/M steels are clearly well-suited for applications requiring high pitting corrosion resistances.

  • 243.
    Freitag, Marina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, Box 523, SE-75120 Uppsala, Sweden.;Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Giordano, Fabrizio
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Yang, Wenxing
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hao, Yan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Zietz, Burkhard
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Graetzel, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Hagfeldt, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Copper Phenanthroline as a Fast and High-Performance Redox Mediator for Dye-Sensitized Solar Cells2016In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 120, no 18, p. 9595-9603Article in journal (Refereed)
    Abstract [en]

    The most commonly used redox mediators in dye-sensitized solar cells (DSCs), iodide/triiodide and cobalt trisbipyridine ([Co(bpy)(3)](2+/3+)), were successfully replaced by bis (2,9-dimethy1-1,10-phenanthroline) copp er (I/H) ([Cu(dmp)(2)](1+/2+)). The use of the copper complex based electrolyte led to an exceptionally high photovoltaic performance of 8.3% for LEG4-sensitized TiO2 solar cells, with a remarkably high open-circuit potential of above 1.0 V at 1000 W m(-2) under AM1.5G conditions. The copper complex based redox electrolyte has higher diffusion coefficients and is considerably faster in dye regeneration than comparable cobalt trisbipyridine based electrolytes. A driving force for dye regeneration of only 0.2 eV is sufficient to obtain unit yield, pointing to new possibilities for improvement in DSC efficiencies. The interaction of the excited dye with components of the electrolyte was monitored using steady-state emission measurements and time-correlated single-photon counting (TC-SPC). Our results indicate bimolecular reductive quenching of the excited LEG4 dye by the [Cu(dmp)(2)](2+) complex through a dynamic mechanism. Excited-state dye molecules can readily undergo bimolecular electron transfer with a suitable donor molecule. In DSCs this process can occur when the excited dye is unable to inject electrons into the TiO2. With a high electrolyte concentration the excited dye can be intercepted with an electron from the electrolyte resulting in the reduced state of the dye. Quenching of the reduced dye by the electrolyte competes with electron injection and results in a lower photocurrent. Quenching of excited LEG4 by complexes of [Cu(dmp)(2)](+), [Co(bpy)(3)](2+), and [Co(bpy)(3)](3+) followed a static mechanism, due ground-state dye-quencher binding. Inhibition of unwanted quenching processes by structural modifications may open ways to further increase the overall efficiency.

  • 244.
    Fu, Lian-Hua
    et al.
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Liu, Yan-Jun
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Ma, Ming-Guo
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Zhang, Xue-Ming
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Xue, Zhi-Min
    Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Microwave-Assisted Hydrothermal Synthesis of Cellulose/Hydroxyapatite Nanocomposites2016In: Polymers, ISSN 2073-4360, E-ISSN 2073-4360, Vol. 8, no 9, article id 316Article in journal (Refereed)
    Abstract [en]

    In this paper, we report a facile, rapid, and green strategy for the synthesis of cellulose/hydroxyapatite (HA) nanocomposites using an inorganic phosphorus source (sodium dihydrogen phosphate dihydrate (NaH(2)PO(4)2H(2)O)), or organic phosphorus sources (adenosine 5-triphosphate disodium salt (ATP), creatine phosphate disodium salt tetrahydrate (CP), or D-fructose 1,6-bisphosphate trisodium salt octahydrate (FBP)) through the microwave-assisted hydrothermal method. The effects of the phosphorus sources, heating time, and heating temperature on the phase, size, and morphology of the products were systematically investigated. The experimental results revealed that the phosphate sources played a critical role on the phase, size, and morphology of the minerals in the nanocomposites. For example, the pure HA was obtained by using NaH(2)PO(4)2H(2)O as phosphorus source, while all the ATP, CP, and FBP led to the byproduct, calcite. The HA nanostructures with various morphologies (including nanorods, pseudo-cubic, pseudo-spherical, and nano-spherical particles) were obtained by varying the phosphorus sources or adjusting the reaction parameters. In addition, this strategy is surfactant-free, avoiding the post-treatment procedure and cost for the surfactant removal from the product. We believe that this work can be a guidance for the green synthesis of cellulose/HA nanocomposites in the future.

    Download full text (pdf)
    fulltext
  • 245.
    Fu, Lixin
    et al.
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Shi, Liyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Wang, Zhuyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhao, Yin
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Yuan, Shuai
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China;Shanghai Univ, Emerging Ind Inst, Jiaxing 314006, Zhejiang, Peoples R China.
    Nanocoating inside porous PE separator enables enhanced ionic transport of GPE and stable cycling of Li-metal anode2019In: Research on chemical intermediates (Print), ISSN 0922-6168, E-ISSN 1568-5675, Vol. 45, no 10, p. 4959-4973Article in journal (Refereed)
    Abstract [en]

    In this paper, a simple and feasible method for preparing gel polymer electrolyte (GPE) with good ionic transport properties and mechanical stability is proposed. A ZrO2/KH570/PU/P123 layer was formed on the outer and inner pore surfaces of PE separator before in situ polymerization by a simple one-step dipping coating process. This coating layer changes the PE separator surface from hydrophobic to hydrophilic, and therefore facilitates the uniform spreading of the GPE precursor solution on the PE surface to enable the formation of highly uniform GPE. Moreover, it effectively compensates the negative effects of in situ gelatinization on the ionic transport behavior of the final PE-supported GPE. This GPE possesses excellent ion transport properties and mechanical stability, as well as improves the static and dynamic interfacial stability with lithium metal anode. When using metallic lithium and LiCoO2 to assemble cells, this PE-supported GPE affords improved C-rate capability, cycling performance and effective dendrite inhibition. [GRAPHICS] .

  • 246. Gao, Feng
    et al.
    Nishihara, Sadafumi
    Brant, William
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Towards Beyond Li-Ion Battery Technologies2017Conference paper (Other academic)
  • 247.
    Gebresenbut, Girma
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Andersson, Mikael Svante
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Beran, Pr™emysl
    Manuel, Pascal
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Gomez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Long range ordered magnetic and atomic structures of the quasicrystal approximant in the Tb-Au-Si system2014In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 26, no 32, p. 322202-Article in journal (Refereed)
    Abstract [en]

    The atomic and magnetic structure of the 1/1 Tb(14)Au(70)Si(16) quasicrystal approximant has been solved by combining x-ray and neutron diffraction data. The atomic structure is classified as a Tsai-type 1/1 approximant with certain structural deviations from the prototype structures; there are additional atomic positions in the so-called cubic interstices as well as in the cluster centers. The magnetic property and neutron diffraction measurements indicate the magnetic structure to be ferrimagnetic-like below 9 K in contrast to the related Gd(14)Au(70)Si(16) structure that is reported to be purely ferromagnetic.

  • 248.
    Gebresenbut, Girma H.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Mikael S.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Gomez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tailoring Magnetic Behavior in the Tb-Au-Si Quasicrystal Approximant System2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 5, p. 2001-2008Article in journal (Refereed)
    Abstract [en]

    A novel synthesis method, "arc-melting-self-flux", has been developed and a series of five Tsai-type 1/1 approximant crystals in the Tb-Au-Si system have been synthesized. The synthesis method, by employing a temperature program which oscillates near the melting and nucleation points of the approximants, has provided high-quality and large single crystals in comparison to those obtained from the standard arc-melting-annealing and self-flux methods. The atomic structures of the approximants have been determined from single-crystal X-ray diffraction data and described using concentric atomic clusters with icosahedral symmetry. The compounds are nearly isostructural with subtle variations; two types of atomic clusters which mainly vary at their cluster centers are observed. One type contains a Tb site at the center, and the other contains a disordered tetrahedron decorated with Au/Si mixed sites. Both cluster types can be found coexisting in the approximants. The compounds have different average weighted ratios of central Tb to disordered tetrahedron in the bulk material. Furthermore, a strategy for chemically tuning magnetic behavior is presented. Magnetic property measurements on the approximants revealed that the magnetic transition temperature (T-c) decreases as the occupancy of the central Tb site increases. T-c decreased from 11.5 K for 0% occupancy of the central Tb to 8 K for 100% occupancy. Enhanced magneto crystalline anisotropy is observed for the approximants with higher central Tb occupancy in comparison to their low central Tb occupancy counterparts. Hence, the previously reported "ferrimagnetic-like" magnetic structure model remains valid.

  • 249.
    Gebresenbut, Girma Hailu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Qureshi, Navid
    Institut Laue Langevin, 6 rue Jules Horowitz, Boîıte Postale 156, F-38042 Grenoble, France.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pay Gómez, Cesar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Single crystal growth, structure determination and magnetic behavior of RE-Au-Si quasicrystal approximants (RE = Ho and Tb)Manuscript (preprint) (Other academic)
  • 250.
    Gebresenbut, Girma Hailu
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tamura, Ryuji
    Eklof, Daniel
    Gomez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Syntheses optimization, structural and thermoelectric properties of 1/1 Tsai-type quasicrystal approximants in RE-Au-SM systems (RE = Yb, Gd and SM = Si, Ge)2013In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, no 13, p. 135402-Article in journal (Refereed)
    Abstract [en]

    Yb-Cd (Tsai-type) quasicrystals constitute the largest icosahedral quasicrystal family where Yb can be replaced by other rare earth elements (RE) and Cd by pairs of p- and d-block elements. YbCd6 is a prototype 1/1 Tsai-type approximant phase which has a similar local structure to the Yb-Cd quasicrystal. In this study, the syntheses of Yb15.78Au65.22Ge19.00, Gd14.34Au67.16Ge18.5 and Gd14.19Au69.87Si15.94 Tsai-type 1/1 quasicrystal approximants are optimized using the self-flux technique. The crystal structures of the compounds are refined by collecting single crystal x-ray diffraction data. The structural refinements indicated that the compounds are essentially isostructural with some differences at their cluster centers. The basic polyhedral cluster unit in all the three compounds can be described by concentric shells of icosahedra symmetry and of disordered tetrahedra and/or a rare earth atom at the cluster center. Furthermore, the thermoelectric properties of the compounds are probed and their dimensionless figures of merit are calculated at different temperatures. A significant difference is observed in their thermoelectric properties, which could arise due to the slight difference in their crystal structure and chemical composition, as we move from Ge to Si and/or Gd to Yb. Therefore, this study shows the systematic effect of the chemical substitution of structurally similar materials on their thermoelectric properties.

2345678 201 - 250 of 912
CiteExportLink to result list
Permanent 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