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  • 251.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Multiscale modelling of metal oxide interfaces and nanoparticles2017Conference paper (Other academic)
    Abstract [en]

    Redox-active metal oxide surfaces and interfaces ‒ such as electrodes, catalysts, and sensors ‒ play crucial roles in our society and in the development of new materials and greener technologies. In the scientific literature, a full arsenal of experimental methods are being used to help characterize such interfaces. At the same time, the number of theoretical studies in the literature steadily increases, providing mechanistic information at a detail that is hard to beat by experiment. Are such theoretical results accurate enough?  Here the major challenges are (i) how to build a structural model that captures the complexity and imperfections of the real system at hand, and (ii) how to find an interaction model/a materials relation (say a DFT functional [1] or a force-field) that is good enough.

    A 5 nm metal oxide nanoparticle may be very small to an experimentalist, but it contains many thousand atoms, making standard quantum-mechanical (e.g. regular DFT) methods totally unfeasible. Can force-field calculations be used instead? Well, mimicking the interactions and chemical properties without explicit electrons present is a formidable task, especially when the transfer of electrons is closely coupled to the material's functionality, as is the case for redox-active metal oxides. I will discuss some of our efforts in the development of a multiscale modelling approach for surfaces and interfaces of metal oxides (e.g. CeO2, ZnO, MgO) – with and without interacting molecules (e.g. O2 and water).

    In summary, we combine a range of theoretical methods including DFT [2], tight-binding-DFT [3], and reactive force-field simulations [4] in a consistent multi-scale approach to examine the properties of oxide nanosystems. We generate images and spectra to make direct comparisons with the experimental couterparts (e.g. IRRAS spectra [5] and a new unpublished approach to predict vibrational spectra for OH-covered metal oxides), but we also generate properties that cannot be measured by experiments such as the water dipole moment enhancement on a surface (oftem much larger than in liquid water!). I will also inform about the European Materials Modelling Council (https://emmc.info/), and our efforts to promote the use of materials modelling in industry and the quality of the modelling results; the EMMC is open to everyone interested.

    References:

    [1] G. G. Kebede, D. Spångberg, P. D. Mitev, P. Broqvist, K. Hermansson, "Comparing van der Waals DFT methods for water on NaCl(001) and MgO(001), The Journal of Chemical Physics 146, 064703 (2017).

     [2] M. Hellström, D. Spångberg, K. Hermansson, "Treatment of Delocalized Electron Transfer in Periodic and Embedded Cluster DFT Calculations: The Case of Cu on ZnO (10-10)", Journal of Computational Chemistry 36, 2394 (2015).

     [3] J. Kullgren, M. J. Wolf, K. Hermansson, Ch. Köhler, B. Aradi,Th. Frauenheim, and P. Broqvist, "Self-Consistent-Charge Density-Functional Tight-Binding (SCC-DFTB) Parameters for Ceria in 0D to 3D". J. Phys. Chem. C  121, 4593−4607 (2017).

     [4] P. Broqvist, J. Kullgren, M. J. Wolf, A. C. T. van Duin, K. Hermansson, "A ReaxFF force-field for ceria bulk, surfaces and nanoparticles", J. Phys. Chem. C 119, 13598 (2015).

     [5] S. Hu, Z. Wang, A. Mattsson, L. Österlund, K. Hermansson, "Simulation of IRRAS Spectra for Molecules on Oxide Surfaces: CO on TiO2(110)", J. Phys. Chem. C 119, 5403 (2015).

  • 252.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Multiscale modelling of reactive metal oxide interfaces2017Conference paper (Other academic)
    Abstract [en]

    Chemically active metal oxide surfaces and interfaces ‒catalysts, sensors, electrodes‒ play crucial roles in our society and in the development of new technologies. Modelling such complex systems is by no means easy, and the computational scientist needs to make shrewd decisions about both the choice of structural model for the interface and the choice of total-energy method. This presentation concerns static and dynamic condensed-matter chemistry modelling of metal oxide surfaces, interfaces, nanoparticles.

     

    I will discuss some of our efforts to develop multiscale modelling protocols for metal oxide surfaces, nanoparticles and interfaces (e.g. CeO2 and ZnO) – with and without interacting molecules. We combine a range of theoretical methods including DFT, tight-binding-DFT, and reactive force-field models. A key question here is whether it is really possible to model redox-active metal oxides without including the electrons?

     

    Adequate models for post-processing of simulation data is as important as the data generation itself, since the post-processing links directly to experimental methods for e.g. surface characterization, such as spectra and images.  I will also discuss some of our efforts in this field.

     

    Chemically active metal oxide surfaces and interfaces ‒catalysts, sensors, electrodes‒ play crucial roles in our society and in the development of new technologies. Modelling such complex systems is by no means easy, and the computational scientist needs to make shrewd decisions about both the choice of structural model for the interface and the choice of total-energy method. .   I will discuss some of our efforts to develop multiscale modelling protocols for metal oxide surfaces, nanoparticles and interfaces (e.g. Ceria and ZnO) – with and without interacting molecules. We combine a range of theoretical methods including DFT, tight-binding-DFT, and reactive force-field models. A key question here is: Is it possible to model redox-active metal oxides without including the electrons?   Adequate models for post-processing of simulation data is as important as the data generation itself, since the post-processing links directly to experimental methods for, e.g., surface characterization, such as spectra and images.  I will also discuss some of our efforts in this field.

    References:

     [1] M. Hellström, K. Jorner, M. Bryngelsson, S.E. Huber, J. Kullgren, Th. Frauenheim, P. Broqvist, "An SCC-DFTB Repulsive Potential for Various ZnO Polymorphs and the ZnO-Water System", J. Phys. Chem. C, 2013, 117, 17004.

    [2] P. Broqvist, J. Kullgren, M. J. Wolf, A. C. T. van Duin, K. Hermansson, "A ReaxFF force-field for ceria bulk, surfaces and nanoparticles", J. Phys. Chem. C, 2015, 119, 13598.

    [3] M. Hellström, D. Spångberg, K. Hermansson, "Treatment of Delocalized Electron Transfer in Periodic and Embedded Cluster DFT Calculations: The Case of Cu on ZnO (10-10)", Journal of Computational Chemistry, 2015, 36, 2394.

    [4] S. Hu, Z. Wang, A. Mattsson, L. Österlund, K. Hermansson, "Simulation of IRRAS Spectra for Molecules on Oxide Surfaces: CO on TiO2(110)", J. Phys. Chem. C, 2015, 119, 5403.

  • 253.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Multi-Scale modelling of water and hydroxide in solids and solutions2017In: Contributions, Section of Natural, Mathematical and Biotechnical Sciences, MASA, ISSN 1857-9027, Vol. 38, no 1, p. 17-26Article in journal (Refereed)
    Abstract [en]

    This report discusses some of the most pressing challenges that need to be overcome for computational con-densed-matter chemistry to become fully accepted, at par with experiments. The prospects are rather bright. By means of a few examples, all connected to the bound water molecule and the hydroxide ion, and their mysteries, the unique capabilities of theoretical calculations to provide new insights and sometimes even surpass experiments in accuracy, will be demonstrated.

  • 254.
    Hermansson, Kersti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Aldongarov, Anuar
    Irgibaeva, Irina
    Ågren, Hans
    Theoretical study on passivation of small CdS clusters2014In: Molecular Physics, Vol. 112, p. 674-682Article in journal (Refereed)
  • 255.
    Hermansson, Kersti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Castleton, C
    Lee, Amy
    Kullgren, J
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Description of polarons in ceria using Density Functional Theory2014In: Journal of Physics Conference Series, Vol. 526, no 012002, p. 1-4Article in journal (Refereed)
  • 256.
    Hermansson, Kersti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hu, Shuanglin
    Formic Acid on TiO2-x(110): Dissociation, Motion, and Vacancy Healing2014In: The Journal of Physical Chemistry C, Vol. 118, p. 14876-14887Article in journal (Refereed)
  • 257.
    Hernández, Guiomar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Naylor, Andrew J.
    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.
    Brandell, Daniel
    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.
    Non-Fluorinated Electrolytes for Si-based Li-ion Battery Anodes2018Conference paper (Other academic)
    Abstract [en]

    Although the performance of lithium-ion batteries has been improved to some extent since the initial commercialization,1 cycling stability, safety and sustainability still present some challenges and concerns. In this regard, the battery electrolyte plays an important role. State-of-the-art electrolytes contain the electrolyte salt LiPF6, susceptible to undergo defluorination reactions and form toxic and corrosive compounds, such as HF. Yet, fluorine-containing electrolytes are often considered necessary for enhanced battery performance. On the other hand, replacing LiPF6 with fluorine-free salts would reduce cost, increase safety and decrease toxicity, both in the manufacturing and recycling processes. Among the available fluorine-free salts, lithium bis(oxalato)borate (LiBOB) is a viable candidate due to its enhanced thermal stability.2 Furthermore, additives in the electrolyte are another common source of fluorine, not least fluoroethylene carbonate (FEC) which can form a stable solid electrolyte interface (SEI).3

    Herein, we compare the cell performance of fluorinated and non-fluorinated electrolytes in NMC/Si-Graphite full cells. Three electrolytes are tested: (1) LP57 (1 M LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC) 3:7 vol/vol); (2) LP57 with 10 wt% FEC and 2 wt%  vinylene carbonate (VC); and (3) 0.7 M LiBOB in EC:EMC 3:7 vol/vol and 2 wt% VC.

    The cells containing the conventional electrolyte, LP57, feature a rapid capacity fade and continuous decrease in coulombic efficiency. The cell performance is improved when adding SEI-forming additives to the electrolyte (LP57 with FEC and VC). In addition, stable cycling for over 200 cycles are obtained for both the fluorinated (LP57 with FEC and VC) and non-fluorinated (LiBOB with VC) electrolytes.

    Characterisation by X-ray photoelectron spectroscopy (XPS) of the anode surface showed higher amounts of carbonate species and a thicker SEI layer with the non-fluorinated electrolyte compared to the fluorinated one.

    1 J. Electrochem. Soc. 2017, 164, A5019-A5025.

    2 ChemSusChem 2017, 10, 2431-2448.

    3 J. Electrochem. Soc. 2014, 161, A1933-A1938.

  • 258.
    Herstedt, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Andersson, Anna M
    ABB.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Siegbahn, Hans
    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.
    Characterisation of the SEI formed on natural graphite in PC-based electrolytes2004In: Electrochimica Acta, ISSN 0013-4686, Vol. 49, p. 4939-4947Article in journal (Refereed)
  • 259.
    Herstedt, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Fransson, Linda
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Rate capability of natural graphite as anode material in Li-ion batteries2003In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 124, no 1, p. 191-196Article in journal (Refereed)
    Abstract [en]

    Jet-milled natural Swedish graphite has been evaluated as an anode material for Li-ion battery applications, with a focus on rate capability of the material. The material was found to have a superior rate capability compared to other carbon materials with similar particle sizes. It could also intercalate and deintercalate lithium reversibly in an electrolyte based on propylene carbonate:ethylene carbonate (1:1). Jet-milling was found to increase the amount of rhombohedral phase (3R) in the material from 15 to 40%. However, after repeated electrochemical intercalation and deintercalation of lithium, the amount of 3R phase decreases to ~5%. Neither rate capability nor PC-tolerance can therefore be correlated to the amount of 3R phase.

  • 260.
    Herstedt, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry.
    Rensmo, Håkan
    Siegbahn, Hans
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrolyte additives for enhanced thermal stability of the graphite anode interface in Li-ion batteryIn: Electrochimica Acta, ISSN 0013-4686Article in journal (Refereed)
  • 261.
    Herstedt, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Stjerndahl, Mårten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nytén, Anton
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry. 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.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ravet, Natalie
    Armand, Michel
    Thomas, John O
    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.
    Surface Chemistry of Carbon-Treated LiFePO4 Particles for Li-Ion Battery Cathodes Studied by PES2003In: Electrochemical and Solid-State Letters, ISSN 1099-0062, Vol. 6, no 9, p. A202-A206Article in journal (Refereed)
  • 262.
    Herstedt, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Stjerndahl, Mårten
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nytén, Anton
    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.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ravet, Nathalie
    Armand, Michel
    Thomas, John O
    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.
    The surface chemistry of carbon-treated LiFePO4 particles for Li-ion battery cathodes studied by Photoelectron Spectroscopy2003In: Electrochemical and Solid-State Letters, ISSN 1099-0062, Vol. 6, no 9, p. A202-A206Article in journal (Refereed)
  • 263.
    Hiroto, Takanobu
    et al.
    Department of Materials Science and Technology, Tokyo University of Science, Niijuku, Tokyo 125-8585, Japan.
    Gebresenbut, Girma Hailu
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gómez, Cesar Pay
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Muro, Y
    Liberal Arts and Science, Toyama Prefectural University, Imizu, Toyama 939-0398, Japan.
    Isobe, M
    Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
    Ueda, Y
    Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan.
    Tokiwa, K
    Department of Applied Electronics, Tokyo University of Science, Niijuku, Tokyo 125-8585, Japan.
    Tamura, Ryuji
    Department of Materials Science and Technology, Tokyo University of Science, Niijuku, Tokyo 125-8585, Japan.
    Ferromagnetism and re-entrant spin-glass transition in quasicrystal approximants Au-SM-Gd (SM = Si, Ge)2013In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 25, no 42, p. 426004-Article in journal (Refereed)
    Abstract [en]

    Magnetic susceptibility and specific heat measurements on quasicrystalline approximants Au–Si–Gd and Au–Ge–Gd reveal that a ferromagnetic (FM) transition occurs at Tc = 22.5(5) °K for Au–Si–Gd and at Tc = 13(1) °K for Au–Ge–Gd, which are the first examples of ferromagnetism in crystalline approximants. In addition, a re-entrant spin-glass (RSG) transition is observed at TRSG = 3.3 °K for Au–Ge–Gd in contrast to Au–Si–Gd. The different behaviors are understood based on the recent structural models reported by Gebresenbut et al (2013 J. Phys.: Condens. Matter 25 135402). The RSG transition in Au–Ge–Gd is attributed to a random occupation of the center of the Gd12 icosahedron by Gd atoms; a central Gd spin hinders the long-range FM order.

  • 264.
    Hollmark, H.M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Duda, Laurent-Claudius
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Dahbi, Mohammed
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    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.
    Resonant Soft X-Ray Emission Spectroscopy and X-Ray Absorption Spectroscopy on the Cathode Material LiNi0.65Co0.25Mn0.1O22010In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 8, p. A962-A966Article in journal (Refereed)
  • 265.
    Hollmark, H.M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Maher, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    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.
    Duda, Laurent-Claudius
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Resonant inelastic X-ray scattering and X-ray absorption spectroscopy on the negative electrode material Li0.5Ni0.25TiOPO4 in a Li-ion battery2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 14, p. 6544-6551Article in journal (Refereed)
  • 266.
    Hollmark, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Gustafsson, Torbjörn
    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.
    Duda, Laurent-C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Resonant inelastic X-ray scattering and X-ray absorption spectroscopy on the cathode materials LiMnPO4 and LiMn0.9Fe0.1PO4: A comparative study2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 45, p. 20215-20222Article in journal (Refereed)
    Abstract [en]

    We present a study of the charge-state behavior of the Li-ion battery cathode materials LixMnPO4 and LixMn0.9Fe0.1PO4 usingx-ray absorption spectroscopy (XAS) and resonant inelastic x-ray scattering (RIXS). A set of six identical battery cathodesfor each material have been cycled and left in different charge states in the range of x=0.2...1.0 before disassembly in an Arglove box. Unexpectedly, we find that the Mn 3d-bands are almost inert to the delithiation process, suggesting that Mn ionsparticipate to a very small extent in the charge compensation process. In LixMn0.9Fe0.1PO4 the Fe 3d-band shows much moreresponse to delithiation than the Mn 3d-band. The O 2p-band hybridizes with the bands of the other ions in LixMnPO4 and LixMn0.9Fe0.1PO4 and thus, indirectly, carries useful information about the effects of delithiation at all ion sites. We conclude,that the redox reactions during lithiation/delithiation of these materials are complex and involve repopulation of charges for allconstituent elements.

  • 267.
    Hollmark, Håkan M.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Dahbi, Mohammed
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Gustafsson, Torbjörn
    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.
    Resonant Soft X-Ray Emission Spectroscopy and X-Ray Absorption Spectroscopy on the Cathode Material LiNi0.65Co0.25Mn0.1O22010In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 157, no 8, p. A962-A966Article in journal (Refereed)
    Abstract [en]

    We present a study of the charge-state behavior of the Li-ion battery cathode material LixNi(0.65)Co(0.25)Mn(0.1)O(2) as observed by X-ray absorption spectroscopy (XAS) and resonant soft X-ray emission (RSXE). A set of six identical Li//LixNi0.65Co0.25Mn0.1O2 batteries has been cycled and is studied in different states of charge in the range of x = 1.0, ... ,0.2 before disassembly in an Ar glove box. Site and symmetry selective information about the electronic structure of the conduction and valence bands reveals that Ni as well as Co ions participate in the uptake and release of the extra electron charge that the inserted Li ions provide, but the Ni ion is much less than expected. The net amount of charge on the oxygen varies approximately 0.24 charge units in the range of x, and dramatic changes in the hybridization are evident in XAS and in particular in RSXE at the O K edge. We attribute this to a strong screening behavior of the Li ions between the oxide layers. Structural integrity effects limit the extraction of Li ions to a value of about x = 0.2-0.4. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3454739] All rights reserved.

  • 268.
    Hollmark, Håkan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Maher, Kenza
    ECME, FST Marrakech, University Cadi Ayyad, BP549, Av. A. Khattabi, Marrakech, Morocco.
    Saadoune, Ismael
    ECME, FST Marrakech, University Cadi Ayyad, BP549, Av. A. Khattabi, Marrakech, Morocco.
    Gustafsson, Torbjörn
    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.
    Duda, Laurent-C.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Soft X-Ray Physics.
    Resonant inelastic X-ray scattering and X-ray absorption spectroscopy on the negative electrode material Li0.5Ni0.25TiOPO4 in a Li-ion battery2011In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 13, no 14, p. 6544-6551Article in journal (Refereed)
    Abstract [en]

    We have studied the first lithiation/delithiation cycle of the Li-ion battery electrode material LixNi0.25TiOPO4 applying X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). A set of ten identical LixNi0.25TiOPO4 battery electrodes have been cycled and left in different states of charge in the range of x = 0.5 … 2.5, before disassembly in an Ar filled glove box. We find that Ni-, Ti-, and O-ions are affected simultaneously, rather than sequentially, upon lithiation of the material. In particular, Ni is reduced from Ni2+ to Ni0 but only partially re-oxidized to Ni1+, again, by delithiation. Overall, there is considerable “crosstalk” between the different atomic species and non-linearity in the response of the electronic structure during the lithiation/delithiation process. Fortuitously, the background variation in Ni L-XAS shows to contain valuable information about solid–electrolyte interface (SEI) creation, showing that the SEI is a function of the degree of lithiation.

  • 269.
    House, Robert A.
    et al.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England.
    Maitra, Urmimala
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England;Justus Liebig Univ Giessen, Inst Phys Chem, Heinrich Buff Ring 17,Room B48, D-35392 Giessen, Germany.
    Jin, Liyu
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England.
    Lozano, Juan G.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England.
    Somerville, James W.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England.
    Rees, Nicholas H.
    Univ Oxford, Dept Chem, Mansfield Rd, Oxford OX1 3TA, England.
    Naylor, Andrew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Massel, Felix
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Chadwick, Alan V.
    Univ Kent, Sch Phys Sci, Canterbury CT2 7NH, Kent, England.
    Ramos, Silvia
    Univ Kent, Sch Phys Sci, Canterbury CT2 7NH, Kent, England.
    Pickup, David M.
    Univ Kent, Sch Phys Sci, Canterbury CT2 7NH, Kent, England.
    McNally, Daniel E.
    Paul Scherrer Inst, Swiss Light Source, Photon Sci Div, CH-5232 Villigen, Switzerland.
    Lu, Xingye
    Paul Scherrer Inst, Swiss Light Source, Photon Sci Div, CH-5232 Villigen, Switzerland.
    Schmitt, Thorsten
    Paul Scherrer Inst, Swiss Light Source, Photon Sci Div, CH-5232 Villigen, Switzerland.
    Roberts, Matthew R.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England.
    Bruce, Peter G.
    Univ Oxford, Dept Mat, Parks Rd, Oxford OX1 3PH, England;Univ Oxford, Faraday Inst, Mansfield Rd, Oxford OX1 3TA, England;Univ Oxford, Dept Chem, Mansfield Rd, Oxford OX1 3TA, England.
    What Triggers Oxygen Loss in Oxygen Redox Cathode Materials?2019In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 31, no 9, p. 3293-3300Article in journal (Refereed)
    Abstract [en]

    It is possible to increase the charge capacity of transition metal (TM) oxide cathodes in alkali-ion batteries by invoking redox reactions on the oxygen. However, oxygen loss often occurs. To explore what affects oxygen loss in oxygen redox materials, we have compared two analogous Na-ion cathodes, P2-Na0.67Mg0.28Mn0.72O2 and P2-Na0.78Li0.25Mn0.75O2. On charging to 4.5 V, >0.4e(-) are removed from the oxide ions of these materials, but neither compound exhibits oxygen loss. Li is retained in P2-Na0.78Li0.25Mn0.25O2 but displaced from the TM to the alkali metal layers, showing that vacancies in the TM layers, which also occur in other oxygen redox compounds that exhibit oxygen loss such as Li[Li0.2Ni0.2Mn0.6]O-2, are not a trigger for oxygen loss. On charging at 5 V, P2-Na0.78Li0.25Mn0.75O2 exhibits oxygen loss, whereas P2-Na0.67Mg0.28Mn0.72O2 does not. Under these conditions, both Na+ and Li+ are removed from P2-Na0.78Li0.25Mn0.75O2, resulting in underbonded oxygen (fewer than 3 cations coordinating oxygen) and surface-localized O loss. In contrast, for P2-Na0.67Mg0.28Mn0.72O2, oxygen remains coordinated by at least 2 Mn4+ and 1 Mg2+ ions, stabilizing the oxygen and avoiding oxygen loss.

  • 270.
    Hu, Shuanglin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bopp, Philippe A.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Broqvist, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Herrnansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Formic Acid on TiO2-x (110): Dissociation, Motion, and Vacancy Healing2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 27, p. 14876-14887Article in journal (Refereed)
    Abstract [en]

    The adsorption and dissociation of a formic acid molecule (HCOOH) on a partially reduced rutile TiO2-x (110) surface and the subsequent transformations of the adsorbed fragments are studied via quantum-mechanical molecular dynamics simulations and climbing-image nudged elastic band (CI-NEB) calculations. The electronic structure methods used are self-consistent-charge density functional tight binding (SCC-DFTB) and DFT+U calculations. We address the apparent lack of consensus in the literature regarding the formic acid adsorbate species that heal the O vacancies, where different experiments have suggested the occurrence of one, two, or no such species types. From our calculations, we propose that the formic acid molecule quickly dissociates on the surface into a formate ion and a proton. If no mechanism exists by which the dissociation products can migrate away from each other, three formate species will coexist on the partially reduced TiO2 surface: one majority species bound to the Ti rows and two minority species healing the O vacancies. However, if such a diffusion mechanism does exist, our barrier calculations show that one of the minority species will transform into the other, and only two adsorbate types can be expected on the surface. We also identify a new adsorbate configuration (which we denote C'), where the formate is located on the row of two-coordinated oxygen atoms, healing an O vacancy and accepting an H-bond from the detached H atom.

  • 271.
    Hu, Shuanglin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Li, Shuyi
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ahuja, Rajeev
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Granqvist, Claes-Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Scheicher, Ralph H.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Optical properties of Mg-doped VO2: Absorption measurements and hybrid functional calculations2012In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 101, no 20, p. 201902-Article in journal (Refereed)
    Abstract [en]

    Mg-doped VO2 thin films with thermochromic properties were made by reactive DC magnetron co-sputtering onto heated substrates, and spectral absorption was recorded at room temperature in the 0.5 < <(h)over bar>omega < 3.5 eV energy range. Clear evidence was found for a widening of the main band gap from 1.67 to 2.32 eV as the Mg/(V + Mg) atomic ratio went from zero to 0.19, thereby significantly lowering the luminous absorption. This technologically important effect could be reconciled with spin-polarized density functional theory calculations using the Heyd-Scuseria-Ernzerhof [Heyd et al., J. Chem. Phys. 118, 8207 (2003); ibid. 124, 219906 (2006)] hybrid functional. Specifically, the calculated luminous absorptance decreased when the Mg/(V + Mg) ratio was increased from 0.125 to 0.250.

  • 272.
    Hu, Shuanglin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wang, Zhuo
    Mattsson, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Österlund, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Simulation of IRRAS Spectra for Molecules on Oxide Surfaces: CO on TiO2(110)2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 10, p. 5403-5411Article in journal (Refereed)
    Abstract [en]

    We explore a method that cart sirriulate infrared refiection absotption spectroscopy (IRRAS) spectra for molecules adsjorlied on semiconductor surfaces. The method rakes it possible to directly correlate experimental spectra with possible adsorbate structures. Our example in thiS paper is CO adsoihed on rutile TiO2(110). We present simulated IRRAS spectra for coverages in the range from 0.125 to 1.5 Monolayer (ML) An explanation is provided. for the apparent inconsistency in the literature concerning the tilting geometry of 1 ML CO on this surface. We find that a tilted structure (which is also the lowest-energy configuration) generates IRRAS spectra in excellent agreement with the experimental spectra. Furthermore, we predict the adsorption structure for 1.5 ML CO coverage over TiO2 (110), which consists of very weakly bound CO molecules on top of the monolayer. In all cases, our simulation method) which is based On density functioual theory (PFT) vibrational calculations, produces s- and p-polarized IRRAS spectra in excellent agreement with the experimental spectra.

  • 273.
    Huber, Stefan E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hellström, Matti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Probst, Michael
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Broqvist, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Large-scale SCC-DFTB calculations of reconstructed polar ZnO surfaces2014In: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 628, p. 50-61Article in journal (Refereed)
    Abstract [en]

    We present a theoretical study of a range of surface defects for the most abundant polar ZnO(0001)/(000 (1) over bar) surfaces using a tight binding approach with self-consistent charges (SCC-DFTB). We find that a combination of triangular pits at the Zn-terminated surface and a strongly ordered hexagonal defect pattern at the O-terminated surface constitutes a very stable reconstruction, in excellent agreement with experimental findings. On the whole, the SCC-DFTB method describes the polar surfaces of ZnO very well, and at a low computational cost which allows for the investigation of larger - and more realistic - surface structures compared to previous studies. Such large-scale calculations show that, at the Zn-terminated surface, the reconstruction results in a high density of one-layer deep triangular pit-like defects and surface vacancies which allow for a high configurational freedom and a vast variety of defect motifs. We also present extensive tests of the performance of the SCC-DFTB method in comparison with DFT results.

  • 274.
    Hudl, Matthias
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Nordblad, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Ivanov, Sergey
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bazuev, G.V.
    nstitute of Solid-State Chemistry, Ural Branch of the Russian Academy of Science, Ekaterinburg, Russia.
    Lazor, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Solid Earth Geology.
    Investigation of the magnetic phase transition and magnetocaloric properties of the Mn2FeSbO6 ilmenite2013In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 331, p. 193-197Article in journal (Refereed)
    Abstract [en]

    The magnetic phase transition and magnetocaloric properties of both mineral and synthetic melanostibite Mn2FeSbO6 with ilmenite-type structure have been studied. Mn2FeSbO6 orders ferrimagnetically below 270 K and is found to undergo a second-order magnetic phase transition. The associated magnetic entropy change was found to be 1.7 J/kg K for the mineral and 1.8 J/kg K for the synthetic melanostibite for 5 T field change. For the synthetic Mn2FeSbO6 the adiabatic temperature change was estimated from magnetic- and specific heat measurements and amounts to 0.2 K in 1 T field change. Perspectives of the functional properties of Mn2FeSbO6-based materials are discussed.

  • 275.
    Högström, Jonas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fredriksson, Wendy
    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.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Olsson, Claes-O. A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cation profiling of passive films on stainless steel formed in sulphuric and acetic acid by deconvolution of angle-resolved X-ray photoelectron spectra2013In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 284, p. 700-714Article in journal (Refereed)
    Abstract [en]

    An approach for determining depth gradients of metal-ion concentrations in passive films on stainlesssteel using angle-resolved X-ray photoelectron spectroscopy (ARXPS) is described. The iterative method,which is based on analyses of the oxidised metal peaks, provides increased precision and hence allowsfaster ARXPS measurements to be carried out. The method was used to determine the concentrationdepth profiles for molybdenum, iron and chromium in passive films on 316L/EN 1.4432 stainless steelsamples oxidised in 0.5 M H2SO4 and acetic acid diluted with 0.02 M Na2B4O7 · 10H2O and 1 M H2O,respectively. The molybdenum concentration in the film is pin-pointed to the oxide/metal interface andthe films also contained an iron-ion-enriched surface layer and a chromium-ion-dominated middle layer.Although films of similar composition and thickness (i.e., about 2 nm) were formed in the two electrolytes,the corrosion currents were found to be three orders of magnitude larger in the acetic acid solution.The differences in the layer composition, found for the two electrolytes as well as different oxidationconditions, can be explained based on the oxidation potentials of the metals and the dissolution rates ofthe different metal ions.

  • 276.
    Höök, Niclas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Database and Modeling of Field Test Data fromLithium Ion Batteries in Hybrid Electrical Vehicles.2011Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In this thesis information received from a hybrid vehicle battery test equipment wasstructured and analyzed. This test equipment is currently placed on a fleet of Scaniatrucks with the purpose of emulating hybrid vehicle environment on battery cell level.A Microsoft Access database structure was set up in order to make it possible to savetest data in a structured way. In addition, Matlab scripts were made with the purposeof calculating cell aging from pulse- and capacity tests. Furthermore, drive cycleanalysis was performed looking at statistics for selected parameters. Data collectedfrom late October 2010 until beginning of July does not yet show any aging of the fieldtested battery cells regarding capacity loss or resistance increase. The internalresistance of the batteries was calculated to 2 to 4 milli ohm and the capacity wasfrom the tests found to be around 3 ampere hours. The energy efficiency, which wascalculated from pulse test data, shows an efficiency between 95 to 97%.

  • 277.
    Ihrfors, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Binder-free oxide nanotube electrodes for high energy and power density 3D Li-ion microbatteries2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis covers synthesis and characterisation of TiO2 nanotubes and TiO2 / Li4Ti5O12 composite nanotubes. The aim was to build batteries with high areal capacity and good rate capability. TiO2 nanotubes were synthesized by two step anodization of titanium metal foil and the composite electrodes were synthesized through electrochemical lithiation of TiO2 nanotubes. To improve the battery performance the TiO2 nanotubes were annealed at 350 °C in air atmosphere, while the composite electrodes were annealed in argon at 550 °C. The longest TiO2 nanotubes were measured to 42.5 μm. The 40 μm long nanotubes displayed an areal capacity of 1.0 mAh/cm2 and a gravimetric capacity of 89 mAh/g. Nanotubes having a length of 10 μm had an areal capacity of 0.33 mAh/cm2 and a gravimetriccapacity of 130 mAh/g. When cycled at high rates, 10C, the capacity of the 40 μm nanotubes was 0.25 mAh/cm2, using a current density of 9.3 mA. The capacity of the 40 μm long nanotubes were higher than for the 10 μm long, but the increase was not proportional to the increase in length. A composite electrode was successfully synthesized and was found to have a capacity of 0.25 mAh/cm2 at a rate of C/5.

  • 278.
    Ihrfors, Charlotte
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wei, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic 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.
    Manufacturing and electrochemical characterization of freestanding TiO2 nanotube electrodes for lithium-ion batteries2016Conference paper (Other academic)
    Abstract [en]

    Microelectronic systems are continuously developed towards smaller and smaller devices which increase the demands on the energy and power densities of the batteries that are used to power the devices. As the size of the electronic components decreases the foot print area available for the surface mounted batteries becomes a limiting factor. These high demands on the energy and power densities make three-dimensional (3D) lithium-ion microbatteries a promising alternative while traditional thin film lithium-ion batteries are less suitable [1, 2] as it is difficult to obtain both high energy and power densities for this type of batteries. The 3D microbatteries can, on the other hand, provide high energy densities per footprint area as well as high power densities thanks to the short diffusion paths and increased mass loading when compared to thin film batteries [1, 3, 4].

    It is well-known that self-assembled freestanding TiO2 nanotubes with a hexagonal structure can be synthesized through an anodization of titanium foil in a fluoride containing electrolyte [5]. This 3D structure can then be annealed to convert the as-formed amorphous TiO2 to anatase. Such annealed nanotubes can readily be used as binder-free anode material for lithium-ion batteries. The high capacity per footprint area and good cycling stability of the TiO2 nanotubes make them suitable for applications in 3D microbatteries [3].

    In this work TiO2 nanotubes of different lengths from 4.5 to 40 µm have been synthesized through a two-step anodization process. The material properties of the nanotubes have been analysed with scanning electron microscopy and X-ray diffraction and the electrochemical performances of nanotubes of different lengths have been evaluated, using galvanostatic cycling and cyclic voltammetry in cells containing lithium-foil counter electrodes. The rate limiting factors during the lithiation and delithiation at high cycling rates have been studied for different tube lengths in addition to the cycling stability of nanotubes with different lengths.

     

    References

    1. Roberts M., Johns P., Owen J., Brandell D., Edström K., Enany G. E., Guery C., Golodonitsky D., Lacey M., Lecoeur C., Mazor H., Peled E., Perre E., Shaijumon M. M., Simon P., Taberna P. -L., 3D lithium ion batteries—from fundamentals to fabrication. J. Mater. Chem. 2011, 21, 9876–9890.
    2. Edström K., Brandell D., Gustafsson T., Nyholm L., Electrodeposition as a tool for 3D microbattery fabrication. Electrochem. Soc. Interface. 2011, 20, 41–46.
    3. Wei W., Oltean G., Tai C. –W., Edström K., Björefors F., Nyholm L., High energy and power density TiO2 nanotube electrodes for 3D Li-ion microbatteries. J. Mater. Chem. A. 2013, 1, 8160-8169.
    4. Yiping T., Xiaoxu T., Guangya H., Guoqu Z., Nanocrystalline Li4Ti5O12-coated TiO2 nanotube arrays as three-dimensional anodes for lithium-ion batteries. Electrochimica Acta. 2014, 117, 172–178.
    5. Roy P., Berger S., Schmuki P., TiO2 Nanotubes: Synthesis and Applications. Angew. Chem. Int. Ed. 2011, 50, 2904–2939.
  • 279.
    Ihrfors, Charlotte
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wei, Wei
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic 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.
    Manufacturing of TiO2 nanotubes for lithium-ion batteries2015Conference paper (Other academic)
    Abstract [en]

    Microelectronic equipment is continuously getting smaller and smaller and thus sets higher and higher demands on the energy and power densities of the batteries that are used to drive them. For surface mounted batteries the surface area of the battery becomes more and more important as the size of the electronic components decreases. The high demands on the energy and power densities per footprint area render the traditional thin film lithium-ion batteries unsuitable and 3D microbatteries are instead proposed to meet these new demands [1, 2]. The high surface area, short diffusion paths and increased mass loadings compared to for thin film batteries makes it possible for the 3D microbatteries to provide a higher energy density per footprint area as well as a high power density [1, 3, 4].

    Electrochemical anodization of titanium foil in fluoride containing electrolytes makes it possible to grow self-assembled TiO2 nanotubes with an almost perfect hexagonal structure. This 3D structure has been shown to perform well as a binder free anode material for lithium-ion batteries and the nanotubes are usually annealed to convert the as-formed TiO2 to anatase. The TiO2 nanotubes have shown a high capacity per footprint area and a good cycling stability which makes them suitable for applications in 3D microbatteries [3].

    In the work presented here TiO2 nanotubes of different lengths, i.e. from 4.5 to 40 µm, have been synthesized employing an anodization approach. The obtained nanotubes, which were characterized with scanning electron microscopy and X-ray diffraction experiments, were also evaluated as electrodes in lithium-ion batteries containing lithium foil counter electrodes. The results of these investigations will be discussed.

     

    References

     

    1. Roberts M, Johns P, Owen J, Brandell D, Edstrom K, Enany GE, Guery C, Golodonitsky D, Lacey M, Lecoeur C, Mazor H, Peled E, Perre E, Shaijumon MM, Simon P, Taberna P-L. 3D lithium ion batteries—from fundamentals to fabrication. J. Mater. Chem. 2011;21:9876–90.
    2. Edström K, Brandell D, Gustafsson T, Nyholm L. Electrodeposition as a tool for 3D microbattery fabrication. Electrochem. Soc. Interface. 2011;20:41–6.
    3. Wei W, Oltean G, Tai C-W, Edström K, Björefors F, Nyholm L. High energy and power density TiO2 nanotube electrodes for 3D Li-ion microbatteries. J. Mater. Chem. A. 2013;1:8160-9.
    4. Yiping T, Xiaoxu T, Guangya H, Guoqu Z. Nanocrystalline Li4Ti5O12-coated TiO2 nanotube arrays as three-dimensional anode for lithium-ion batteries. Electrochimica Acta. 2014;117:172–8.
    5. Roy P, Berger S, Schmuki P. TiO2 Nanotubes: Synthesis and Applications. Angew. Chem. Int. Ed. 2011;50:2904–39.
  • 280.
    Imani, Roghayeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Leibniz Univ Hannover, Inst Tech Chem, Callinstr 3, D-30167 Hannover, Germany.;Univ Ljubljana, Fac Elect Engn, Biophys Lab, SI-1000 Ljubljana, Slovenia..
    Dillert, Ralf
    Leibniz Univ Hannover, Inst Tech Chem, Callinstr 3, D-30167 Hannover, Germany.;Leibniz Univ Hannover, Lab Nano & Quantum Engn, Schneiderberg 39, D-30167 Hannover, Germany..
    Bahnemann, Detlef W.
    Leibniz Univ Hannover, Inst Tech Chem, Callinstr 3, D-30167 Hannover, Germany.;St Petersburg State Univ, Lab Photoact Nanocomposite Mat, St Petersburg 198504, Russia..
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Apih, Tomaz
    Jozef Stefan Inst, Jamova 39, SI-1000 Ljubljana, Slovenia..
    Kononenko, Veno
    Univ Ljubljana, Dept Biol, Biotech Fac, Vecna Pot 111, SI-1000 Ljubljana, Slovenia..
    Repar, Neza
    Univ Ljubljana, Dept Biol, Biotech Fac, Vecna Pot 111, SI-1000 Ljubljana, Slovenia..
    Kralj-Iglic, Veronika
    Univ Ljubljana, Fac Hlth Sci, Biophys Lab, SI-1000 Ljubljana, Slovenia..
    Boschloo, Gerrit
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Drobne, Damjana
    Univ Ljubljana, Dept Biol, Biotech Fac, Vecna Pot 111, SI-1000 Ljubljana, Slovenia..
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Iglic, Ales
    Univ Ljubljana, Fac Elect Engn, Biophys Lab, SI-1000 Ljubljana, Slovenia..
    Multifunctional Gadolinium-Doped Mesoporous TiO2 Nanobeads: Photoluminescence, Enhanced Spin Relaxation, and Reactive Oxygen Species Photogeneration, Beneficial for Cancer Diagnosis and Treatment2017In: Small, ISSN 1613-6810, E-ISSN 1613-6829, Vol. 13, no 20, article id 1700349Article in journal (Refereed)
    Abstract [en]

    Materials with controllable multifunctional abilities for optical imaging (OI) and magnetic resonant imaging (MRI) that also can be used in photodynamic therapy are very interesting for future applications. Mesoporous TiO2 sub-micrometer particles are doped with gadolinium to improve photoluminescence functionality and spin relaxation for MRI, with the added benefit of enhanced generation of reactive oxygen species (ROS). The Gd-doped TiO2 exhibits red emission at 637 nm that is beneficial for OI and significantly improves MRI relaxation times, with a beneficial decrease in spin-lattice and spin-spin relaxation times. Density functional theory calculations show that Gd3+ ions introduce impurity energy levels inside the bandgap of anatase TiO2, and also create dipoles that are beneficial for charge separation and decreased electron-hole recombination in the doped lattice. The Gd-doped TiO2 nanobeads (NBs) show enhanced ability for ROS monitored via center dot OH radical photogeneration, in comparison with undoped TiO2 nanobeads and TiO2 P25, for Gd-doping up to 10%. Cellular internalization and biocompatibility of TiO2@xGd NBs are tested in vitro on MG-63 human osteosarcoma cells, showing full biocompatibility. After photoactivation of the particles, anticancer trace by means of ROS photogeneration is observed just after 3 min irradiation.

  • 281.
    Imani, Roghayeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Fernandes, Daniel L. A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mitev, Pavlin D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Unravelling in-situ formation of highly active mixed metal oxide CuInO2 nanoparticles during CO2 electroreduction2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 49, p. 40-50Article in journal (Refereed)
    Abstract [en]

    Technologies and catalysts for converting carbon dioxide (CO2) to immobile products are of high interest to minimize greenhouse effects. Copper(I) is a promising catalytic active state of copper but hampered by the inherent instability in comparison to copper(II) or copper(0). Here, we report a stabilization of the catalytic active state of copper(I) by the formation of a mixed metal oxide CuInO2 nanoparticle during the CO2 electroreduction. Our result shows the incorporation of nanoporous Sn:In2O3 interlayer to Cu2O pre-catalyst system lead to the formation of CuInO2 nanoparticles with remarkably higher activity for CO2 electroreduction at lower overpotential in comparison to the conventional Cu nanoparticles derived from sole Cu2O. Operando Raman spectroelectrochemistry is employed to in-situ monitor the process of nanoparticles formation during the electrocatalytic process. The experimental data are collaborated with DFT calculations to provide insight into the electro-formation of the type of Cu-based mixed metal oxide catalyst during the CO2 electroreduction, where a formation mechanism via copper ion diffusion across the substrate is suggested.

  • 282.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Beran, P.
    Bazuev, G. V.
    Ericsson, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kumar, P. Anil
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Crystal structure and antiferromagnetic spin ordering of LnFe(2/3)Mo(1/3)O(3) (Ln = Nd, Pr, Ce, La) perovskites2015In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 9, article id 094418Article in journal (Refereed)
    Abstract [en]

    Stoichiometric polycrystalline samples of LnFe(2/3)Mo(1/3)O(3) (Ln = Nd, Pr, Ce, La) have been prepared by solid-state reaction and studied by means of x-ray and neutron powder diffraction as well as Mossbauer spectroscopy and magnetic measurements. All samples were found to be of single phase and to have Pnma symmetry with valence state +3 of Fe and Mo. It is demonstrated that the B-site cations of LnFe(2/3)Mo(1/3)O(3) in accord with LnFeO(3) order in a G-type antiferromagnetic structure with the magnetic moments aligned along the b axis. However, with significantly lower Neel temperatures than their LnFeO(3) parent compounds. The Fe-O-Fe bond lengths and bond angles and thus themagnitude of the antiferromagnetic superexchange interaction are found to systematically change with the ionic radius of Ln such that T-N increases with increasing radius. Only the CeFe2/3Mo1/3O3 compound experiences a low temperature spin reorientation from alignment along the b axis to the a axis.

  • 283.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Center of Materials Science, Karpov Institute of Physical Chemistry, Moscow, Russia..
    Bush, A. A.
    Moscow Technol Univ, Moscow 119434, Russia..
    Hudl, M.
    Stockholm Univ, Dept Phys, SE-10691 Stockholm, Sweden..
    Stash, A. I.
    Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow 105064, Russia..
    Andre, G.
    CEA, Lab Leon Brillouin, Saclay, France..
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cherepanov, V. M.
    Kurchatov Inst, Natl Res Ctr, Moscow 123182, Russia..
    Stepanov, A. V.
    Moscow Technol Univ, Moscow 119434, Russia..
    Kamentsev, K. E.
    Moscow Technol Univ, Moscow 119434, Russia..
    Tokunaga, Y.
    RIKEN Ctr Emergent Matter Sci CEMS, Wako, Saitama 3510198, Japan..
    Taguchi, Y.
    RIKEN Ctr Emergent Matter Sci CEMS, Wako, Saitama 3510198, Japan..
    Tokura, Y.
    RIKEN Ctr Emergent Matter Sci CEMS, Wako, Saitama 3510198, Japan.;Univ Tokyo, Dept Appl Phys, Tokyo 1138656, Japan..
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Spin and dipole order in geometrically frustrated mixed-valence manganite Pb3Mn7O152016In: Journal of materials science. Materials in electronics, ISSN 0957-4522, E-ISSN 1573-482X, Vol. 27, no 12, p. 12562-12573Article in journal (Refereed)
    Abstract [en]

    The structural, magnetic, and dielectric properties of Pb3Mn7O15 have been investigated using high-quality single crystals. Pb3Mn7O15 adopts a pseudo-hexagonal orthorhombic structure, with partially filled Kagom, layers connected by ribbons of edge-sharing MnO6 octahedra and intercalated Pb cations. There are 9 inequivalent sites in the structure for the Mn ions, which exist both as Mn3+ and Mn4+. Pb3Mn7O15 undergoes an antiferromagnetic transition below T-N similar to 67 K, with significant geometric frustration. Neutron powder diffraction on crushed single crystals allowed us to determine the low-temperature antiferromagnetic magnetic structure. We discuss the magnetic interaction pathways in the structure and possible interplay between the structural distortions imprinted by the lone-electron pair of Pb2+ cations and Mn3+/Mn4+ charge ordering.

  • 284.
    Ivanov, Sergey A
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    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.
    Politova, E
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ritter, C
    Institute Laue Langevin, Grenoble Frankrike.
    Proidakova, V
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Structural and magnetic properties of Mn3-xCdxTeO6 (x = 0, 1, 1.5 and 2)2012In: Journal of Magnetism and Magnetic Materials, ISSN 0304-8853, E-ISSN 1873-4766, Vol. 324, no 8, p. 1637-1644Article in journal (Refereed)
    Abstract [en]

    Mn(3)TeO(6) exhibits a corundum-related A(3)TeO(6) structure and a complex magnetic structure involving two magnetic orbits for the Mn atoms [Ivanov et al., 2011 [3]]. Mn(3-x)Cd(x)TeO(6) (x = 0, 1, 1.5, and 2) ceramics were synthesized by solid state reaction and investigated using X-ray powder diffraction, electron microscopy, and calorimetric and magnetic measurements. Cd(2+) replaces Mn(2+) cations without greatly affecting the structure of the compound. The Mn and Cd cations were found to be randomly distributed over the A-site. Magnetization measurements indicated that the samples order antiferromagnetically at low temperature with a transition temperature that decreases with increasing Cd doping. The nuclear and magnetic structure of one specially prepared (114)Cd containing sample: Mn(1.5) (114)Cd(1.5)TeO(6), was studied using neutron powder diffraction over the temperature range 2-295 K. Mn(1.5) (114)Cd(1.5)TeO(6) was found to order in an incommensurate helical magnetic structure, very similar to that of Mn(3)TeO(6) [Ivanov et al., 2011 [3]]. However, with a lower transition temperature and the extension of the ordered structure confined to order 240(10) angstrom.

  • 285.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mathieu, Roland
    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.
    Ritter, C.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Golubko, N
    Mosunov, A
    Politova, E D
    Weil, M
    Chemical pressure effects on structural, dielectric and magnetic properties of solid solutions Mn3-xCoxTeO62014In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 50, p. 42-56Article in journal (Refereed)
    Abstract [en]

    The effects of Co2+ doping on the structural, magnetic and dielectric properties of the multiferroic frustrated antiferromagnet Mn3TeO6 have been investigated. Ceramic samples of the solid solution series Mn3-xCoxTeO6 were prepared by a solid-state reaction route. X-ray and neutron powder diffraction and electron microscopy techniques were combined with calorimetric, dielectric and magnetic measurements to investigate the dependence of the crystal structure and physical properties on temperature and composition. It is shown that the compounds with x <= 2.4 adopt the trigonal corundum-related structure of pure Mn3TeO6 (space group 18) in the temperature range 5-295 K and that the lattice parameters a and c and the unit-cell volume V decrease linearly with increasing Co2+ concentration. The low-temperature magnetic susceptibility and heat capacity data evidence the antiferromagnetic ordering of all samples. The Neel temperature linearly increases with Co2+ concentration x. Curie-Weiss fits of the high temperature susceptibility indicate that the magnetic frustration decreases with x. The derived magnetic structure of Mn3TeO6 can be described as an incommensurately modulated magnetic spin state with k = [0, 0, k(z)] and an elliptical spin-spiral order of spins within the chains of MnO6 octahedra. With increasing Co2+ concentration the propagation vector kz changes from 0.453 (x = 0) to 0.516 (x = 2.4). The magnetic anisotropy changes as well, leading to a reorientation of the spiral-basal plane. A possible coexistence of long-range order of electrical dipoles and magnetic moments in Mn3-xCoxTeO6 is discussed.

  • 286.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    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.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ritter, C.
    Politova, E.
    Kaleva, G.
    Mosunov, A.
    Stefanovich, S.
    Weil, M.
    Spin and Dipole Ordering in Ni2InSbO6 and Ni2ScSbO6 with Corundum-Related Structure2013In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 25, no 6, p. 935-945Article in journal (Refereed)
    Abstract [en]

    The complex metal oxides Ni2InSbO6 (NISO) and Ni2ScSbO6 (NSSO) have been prepared in the form of polycrystalline powders by a solid state reaction route. The crystal structure and magnetic properties of the compounds were investigated using a combination of X-ray and neutron powder diffraction, electron microscopy, calorimetric, and magnetic measurements. The compounds adopt a trigonal structure, space group R3, of the corundum related Ni3TeO6 (NTO) type. Only one of the octahedral Ni positions (Ni(2)) of the NTO structure was found to be occupied by In (Sc). NTO has noncentrosymmetric structure and is ferroelectric below 1000 K; dielectric and second harmonic measurements suggest that also NISO and NSSO are correspondingly ferroelectric. Magnetization measurements signified antiferromagnetic ordering below T-N = 60 K (NSSO) and 76 K (NISO). The magnetic structure is formed by two antiferromagnetically coupled incommensurate helices with the spiral axis along the b-axis and propagation vector k = [0, k(y),0] with k(y) = 0.036(1) (NSSO) and k(y) = 0.029(1) (NISO). The observed structural and magnetic properties of NISO and NSSO are discussed and compared with those of NTO.

  • 287.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Karpov Inst Phys Chem, Ctr Mat Sci, Moscow 105064, Russia..
    Ritter, C.
    Inst Laue Langevin, BP 156, F-38042 Grenoble, France..
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Weil, M.
    Vienna Univ Technol, Inst Chem Technol & Analyt, A-1060 Vienna, Austria..
    Carolus, V.
    Univ Bonn, HISKP, Nussallee 14-16, D-53115 Bonn, Germany..
    Lottermoser, Th
    ETH, Dept Mat, Vladimir Prelog Weg 4, CH-8093 Zurich, Switzerland..
    Fiebig, M.
    ETH, Dept Mat, Vladimir Prelog Weg 4, CH-8093 Zurich, Switzerland..
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    New insights into the multiferroic properties of Mn3TeO62017In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 8, article id 085001Article in journal (Refereed)
    Abstract [en]

    Mn3TeO6 has a trigonal corundum related structure (space group R (3) over bar), and orders in an incommensurate antiferromagnetic (AFM) structure at T-N approximate to 24 K. A weak ferroelectric order below T* similar to 21 K has recently been reported. In order to investigate possible structural changes below T-N leading to the observed dipole order, we have performed a detailed study of the crystal and magnetic structures of Mn3TeO6 using neutron powder diffraction (NPD) in the temperature range of 5-40 K. Complementary low-temperature second harmonic generation (SHG) measurements were performed in order to confirm the reported dipole order at T*. No change in the rhombohedral symmetry associated with a possible displacive phase transition at T* was observed in the long-range structural correlations, and it appears that Mn3TeO6 keeps the same incommensurately modulated magnetic spin structure with the propagation vector k = (0; 0; 0.43) in the whole temperature range from 5 to 24 K.

  • 288.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Porcher, F.
    Andre, G.
    Ericsson, T.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Sadovskaya, N.
    Kaleva, G.
    Politova, E.
    Baldini, M.
    Sun, C.
    Arvanitis, Dimitri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics, Physics V. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Kumar, P. Anil
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Structural and magnetic properties of nickel antimony ferrospinels2015In: Materials Chemistry and Physics, ISSN 0254-0584, E-ISSN 1879-3312, Vol. 158, p. 127-137Article in journal (Refereed)
    Abstract [en]

    Spinel-type compounds of Fe-Ni-Sb-O system were synthesized as polycrystalline powders. The crystal and magnetic properties were investigated using X-ray and neutron powder diffraction, Mossbauer and X-ray absorption spectroscopy and magnetization measurements. The samples crystallize in the cubic system, space group Fd - 3 m. The distribution of cations between octahedral and tetrahedral sites was refined from the diffraction data sets using constraints imposed by the magnetic, Mossbauer and EDS results and the ionic radii. The cation distribution and the temperature dependence of the lattice parameter (a) and the oxygen positional parameter (u) were obtained. A chemical formula close to Fe0.8Ni1.8Sb0.4O4 was determined, with Sb5+ cations occupying octahedral sites, and Fe3+ and Ni2+ occupying both tetrahedral and octahedral sites. Fe3+ mainly (85/15 ratio) occupy tetrahedral sites, and conversely Ni2+ mainly reside on octahedral ones. The magnetic unit cell is the same as the crystallographic one, having identical symmetry relations. The results indicate that the compounds have a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Uniquely, the temperature dependence of the net magnetization of this rare earth free ferrimagnet exhibits a compensation point.

  • 289.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Porcher, F.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Mosunov, A.
    Beran, P.
    Korchaginaa, S.K.
    Anil Kumar, Puri
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    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.
    Preparation, structural, dielectric and magnetic properties of LaFeO3-PbTiO3 solid solutions2012In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, no 11, p. 3253-3268Article in journal (Refereed)
    Abstract [en]

    Solid solutions of (1−x)LaFeO3–(x)PbTiO3 (0 < x < 1) have been prepared by conventional solid-state reaction. These complex perovskites have been studied by means of X-ray (XRPD) and neutron powder (NPD) diffraction, complemented with dielectric, magnetic, heat capacity and Mössbauer measurements. Complete solubility in the perovskite series was demonstrated. The NPD and XRPD patterns were successfully refined as orthorhombic (x ≤ 0.7) and tetragonal (x ≥ 0.8). A composition-driven phase transformation occurs within the interval 0.7 < x < 0.8. The samples with x < 0.5 showed evidence of long-range magnetic ordering with an G-type antiferromagnetic arrangement of the magnetic moments of the Fe3+ cations in the B-site with propagation vector k = (0,0,0). Based on the obtained experimental data, a combined structural and magnetic phase diagram has been constructed. The factors governing the structural, dielectric and magnetic properties of (1−x)LaFeO3–(x)PbTiO3 solid solutions are discussed, as well as their possible multiferroicity.

  • 290.
    Ivanov, Sergey A.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ritter, C.
    Institute Laue Langevin, Grenoble, Frankrike.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Andre, G.
    Laboratoire Leon Brillouin, CEA, Saclay, Frankrike.
    Golubko, N. V.
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Politova, E. D.
    Dept of Inorganic Materials, Karpov' Institute of Physical Chemistry, Moskva, Ryssland.
    Weil, M.
    Institute for Chemical Technologies and Analytics, Vienna University of Technology, Wien, Österrike.
    Temperature-dependent multi-k magnetic structure in multiferroic Co3TeO62012In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 47, no 1, p. 63-72Article in journal (Refereed)
    Abstract [en]

    A complex magnetic order of the multiferroic compound Co(3)TeO(6) has been revealed by neutron powder diffraction studies on ceramics and crushed single crystals. The compound adopts a monoclinic structure (s.g. C2/c) in the studied temperature range 2-300 K but exhibits successive antiferromagnetic transitions at low temperature. Incommensurate antiferromagnetic order with the propagation vector k(1) = (0, 0.485, 0.055) sets in at 26 K. A transition to a second antiferromagnetic structure with k(2) = (0, 0, 0) takes place at 21.1 K. Moreover, a transition to a commensurate antiferromagnetic structure with k(3) = (0, 0.5, 0.25) occurs at 17.4 K. The magnetic structures have been determined by neutron powder diffraction using group theory analysis as a preliminary tool. Different coordinations of the Co(2+) ions involved in the low-symmetry C2/c structure of Co(3)TeO(6) render the exchange-interaction network very complex by itself. The observed magnetic phase transformations are interpreted as an evidence of competing magnetic interactions. The temperature dependent changes in the magnetic structure, derived from refinements of high-resolution neutron data, are discussed and possible mechanisms connected with the spin reorientations are described.

  • 291.
    Ivanov, Sergey
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. Karpov Inst Phys Chem, Ctr Mat Sci, Vorontsovo Pole 10, Moscow 105064, Russia.
    Beran, Premysl
    CAS, Inst Nucl Phys, Rez, Czech Republic.
    Bush, Alexandr A.
    Moscow Technol Univ, Moscow 119454, Russia.
    Sarkar, Tapati
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Shafeie, Samrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Wang, Duo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sanyal, Biplab
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Eriksson, Olle
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Kvashnin, Yaroslav
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Tellgren, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nordblad, Per
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Mathieu, Roland
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Cation ordering, ferrimagnetism and ferroelectric relaxor behavior in Pb(Fe1-xScx)(2/3)W1/3O3 solid solutions2019In: European Physical Journal B: Condensed Matter Physics, ISSN 1434-6028, E-ISSN 1434-6036, Vol. 92, no 8, article id 163Article in journal (Refereed)
    Abstract [en]

    Ceramic samples of the multiferroic perovskite Pb(Fe1-xScx)(2/3)W1/3O3 with 0 <= x <= 0.4 have been synthesized using a conventional solid-state reaction method, and investigated experimentally and theoretically using first-principle calculations. Rietveld analyses of joint synchrotron X-ray and neutron diffraction patterns show the formation of a pure crystalline phase with cubic (Fm3(_)m) structure with partial ordering in the B-sites. The replacement of Fe by Sc leads to the increase of the cation order between the B and B '' sites. As the non-magnetic Sc3+ ions replace the magnetic Fe3+ cations, the antiferromagnetic state of PbFe2/3W1/3O3 is turned into a ferrimagnetic state reflecting the different magnitude of the magnetic moments on the B ' and B '' sites. The materials remain ferroelectric relaxors with increasing Sc content. Results from experiments on annealed and quenched samples show that the cooling rate after high temperature annealing controls the degree of cationic order in Pb(Fe1-xScx)(2/3)W1/3O3 and possibly also in the undoped PbFe2/3W1/3O3.

  • 292.
    Izanzar, Ilyasse
    et al.
    Cadi Ayyad University.
    Dahbi, Mouad
    Mohammed VI Polytechnic University (UM6P).
    Younesi, Reza
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    Cadi Ayyad University.
    Hard Carbon//Na3V2(PO4)3 Full Cell Battery Exhibiting Enhanced Performance2018Conference paper (Refereed)
  • 293.
    Jacobsson, T. Jesper
    et al.
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Correa-Baen, Juan-Pablo
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photomol Sci, CH-1015 Lausanne, Switzerland..
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saliba, Michael
    Ecole Polytech Fed Lausanne, Inst Chem Sci & Engn, Lab Photon & Interfaces, CH-1015 Lausanne, Switzerland..
    Schenk, Kurt
    Ecole Polytech Fed Lausanne, CH-1015 Lausanne, Switzerland..
    Gratzel, 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..
    Exploration of the compositional space for mixed lead halogen perovskites for high efficiency solar cells2016In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 9, no 5, p. 1706-1724Article in journal (Refereed)
    Abstract [en]

    Lead halide perovskites have attracted considerable interest as photoabsorbers in PV-applications over the last few years. The most studied perovskite material achieving high photovoltaic performance has been methyl ammonium lead iodide, CH3NH3PbI3. Recently the highest solar cell efficiencies have, however, been achieved with mixed perovskites where iodide and methyl ammonium partially have been replaced by bromide and formamidinium. In this work, the mixed perovskites were explored in a systematic way by manufacturing devices where both iodide and methyl ammonium were gradually replaced by bromide and formamidinium. The absorption and the emission behavior as well as the crystallographic properties were explored for the perovskites in this compositional space. The band gaps as well as the crystallographic structures were extracted. Small changes in the composition of the perovskite were found to have a large impact on the properties of the materials and the device performance. In the investigated compositional space, cell efficiencies, for example, vary from a few percent up to 20.7%. From the perspective of applications, exchanging iodide with bromide is especially interesting as it allows tuning of the band gap from 1.5 to 2.3 eV. This is highly beneficial for tandem applications, and an empirical expression for the band gap as a function of composition was determined. Exchanging a small amount of iodide with bromide is found to be highly beneficial, whereas a larger amount of bromide in the perovskite was found to cause intense sub band gap photoemission with detrimental results for the device performance. This could be caused by the formation of a small amount of an iodide rich phase with a lower band gap, even though such a phase was not observed in diffraction experiments. This shows that stabilizing the mixed perovskites will be an important task in order to get the bromide rich perovskites, which has a higher band gap, to reach the same high performance obtained with the best compositions.

  • 294.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Functional Binders at the Interface of Negative and Positive Electrodes in Lithium Batteries2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    In this thesis, electrode binders as vital components in the fabrication of composite electrodes for lithium-ion (LIB) and lithium-sulfur batteries (LiSB) have been investigated.

    Poly(vinylidene difluoride) (PVdF) was studied as binder for sulfur-carbon positive electrodes by a combination of galvanostatic cycling and nitrogen absorption. Poor binder swelling in the electrolyte and pore blocking in the porous carbon were identified as origins of low discharge capacity, rendering PVdF-based binders an unsuitable choice for LiSBs. More promising candidates are blends of poly(ethylene oxide) (PEO) and poly(N-vinylpyrrolidone) (PVP). It was found that these polymers interact with soluble lithium polysulfide intermediates generated during the cell reaction. They can increase the discharge capacity, while simultaneously improving the capacity retention and reducing the self-discharge of the LiSB. In conclusion, these binders improve the local electrolyte environment at the electrode interface.

    Graphite electrodes for LIBs are rendered considerably more stable in ‘aggressive’ electrolytes (a propylene carbonate rich formulation and an ether-based electrolyte) with the poorly swellable binders poly(sodium acrylate) (PAA-Na) and carboxymethyl cellulose sodium salt (CMC-Na). The higher interfacial impedance seen for the conventional PVdF binder suggests a protective polymer layer on the particles. By reducing the binder content, it was found that PAA-Na has a stronger affinity towards electrode components with high surface areas, which is attributed to a flexible polymer backbone and a higher density of functional groups.

    Lastly, a graphite electrode was combined with a sulfur electrode to yield a balanced graphite-sulfur cell. Due to a more stable electrode-electrolyte interface the self-discharge of this cell could be reduced and the cycle life was extended significantly. This example demonstrates the possible benefits of replacing the lithium metal negative electrode with an alternative electrode material.

    List of papers
    1. Functional, water-soluble binders for improved capacity and stability of lithium-sulfur batteries
    Open this publication in new window or tab >>Functional, water-soluble binders for improved capacity and stability of lithium-sulfur batteries
    2014 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 264, p. 8-14Article in journal (Refereed) Published
    Abstract [en]

    Binders based on mixtures of poly(ethylene oxide) (PEO) and poly(vinylpyrrolidone) (PVP) are here shown to significantly improve the reversible capacity and capacity retention of lithium- sulfur batteries compared to conventional binders. This mixed binder formulation combines the local improvement to the solvent system offered by PEO and the lithium (poly)sulfide-stabilising effect of PVP. Cells with cathodes made of simple mixtures of sulfur powder and carbon black with a binder of 4:1 PEO:PVP exhibited a reversible capacity of over 1000 mAh g(-1) at C/5 after 50 cycles and 800 mAh g(-1) at 1C after 200 cycles. Furthermore, these materials are water soluble, environmentally friendly and widely available, making them particularly interesting for large-scale production and applications in, for example, electric vehicles. 

    Keywords
    Lithium-sulfur, Binder, Poly(vinylpyrrolidone), Poly(ethylene oxide)
    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:uu:diva-228938 (URN)10.1016/j.jpowsour.2014.04.090 (DOI)000337861800002 ()
    Funder
    StandUp
    Available from: 2014-08-11 Created: 2014-07-24 Last updated: 2017-12-30
    2. Porosity Blocking in Highly Porous Carbon Black by PVdF Binder and Its Implications for the Li-S System
    Open this publication in new window or tab >>Porosity Blocking in Highly Porous Carbon Black by PVdF Binder and Its Implications for the Li-S System
    2014 (English)In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 45, p. 25890-25898Article in journal (Refereed) Published
    Abstract [en]

    In this work, the influence of cathode binders on the porosity of composite electrodes for lithiumsulfur (LiS) batteries employing high surface area carbon blacks has been closely scrutinized. This has been accomplished by comparison of PVdF with the related copolymer, PVdF-HFP. Analysis of carbon black porosity after addition of binder in NMP solution reveals that PVdF(-HFP) fills pores of almost any size in carbon black, which can effect a severe reduction in pore volume and surface area accessible to the electrolyte in a LiS cell. Noting the different swelling behavior of both binders, the implications of pore filling by the binder on the electrochemistry of LiS cells can be determined. Because of the low swellability of PVdF in dimethoxyethane:dioxolane (DME:DOL)-based electrolytes, access of the electrolyte to the carbon surface area and pore volume is restricted, with potentially severe detrimental effects on the available capacity of the cell. Furthermore, this effect is still clearly significant for common binder loadings and with preinfiltration of sulfur; this study is therefore a clear demonstration that PVdF is an unsuitable choice of binder for the lithiumsulfur system and that alternatives must be considered.

    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-239773 (URN)10.1021/jp508137m (DOI)000344978000009 ()
    Funder
    StandUp
    Available from: 2014-12-30 Created: 2014-12-30 Last updated: 2017-12-30
    3. Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries
    Open this publication in new window or tab >>Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries
    2015 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, p. 141-150Article in journal (Refereed) Published
    Abstract [en]

    A comparative study of various electrode binders for graphite electrodes was conducted in a carbonate-based electrolyte with a high content of propylene carbonate (PC) as a means to evaluate anode degradation in presence of different binders. Because of its direct contact with the active material, a binder can be interpreted as an interfacial layer and as a local part of the electrolyte, the properties of which greatly depend on the interaction with the liquid electrolyte. In this work we demonstrate how a carefully chosen binder can create a specific surface environment that can protect graphite from exfoliation when the binder exhibits poor solubility in the electrolyte solvent and good surface adhesion to the active material. The exceptional stability of graphite electrodes containing poly(acrylic acid) sodium salt (PAA-Na) and carboxymethyl cellulose sodium salt (CMC-Na), respectively, in a PC-rich electrolyte is explained through the understanding of binder swelling and functionality. Interfacial resistances and electrochemical stability were investigated with impedance spectroscopy and galvanostatic cycling. Electrode morphologies and distributions of material were analysed with SEM and EDX. Evidence is presented that the surface selectivity increases with concentration of functional groups and polymer flexibility. Therefore only the less selective, stiff polymer with less functional groups, CMC-Na, provides sufficient protection at low binder contents.

    Keywords
    Binder, graphite exfoliation, CMC, propylene carbonate, SEI
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-262960 (URN)10.1016/j.electacta.2015.03.072 (DOI)000360178600019 ()
    Funder
    Swedish Research Council, 2012-3837
    Available from: 2015-09-29 Created: 2015-09-23 Last updated: 2017-12-01Bibliographically approved
    4. A stable graphite negative electrode for the lithium-sulfur battery
    Open this publication in new window or tab >>A stable graphite negative electrode for the lithium-sulfur battery
    2015 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 96, p. 17100-17103Article in journal (Refereed) Published
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-267760 (URN)10.1039/C5CC06666B (DOI)000367469400011 ()26451894 (PubMedID)
    Funder
    Swedish Research Council, 2012-3837VINNOVAStandUp
    Available from: 2015-11-26 Created: 2015-11-26 Last updated: 2017-12-30
  • 295.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Polymers at the Electrode-Electrolyte Interface: Negative Electrode Binders for Lithium-Ion Batteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    We are today experiencing an increasing demand for high energy density storage devices like the lithium-ion battery for applications in portable electronic devices, electric vehicles (EV) and as interim storage for renewable energy. High capacity retention and long cycle life are prerequisites, particularly for the EV market. The key for a long cycle life is the formation of a stable solid-electrolyte interphase (SEI) layer on the surface of the negative electrode, which typically forms on the first cycles due to decomposition reactions at the electrode-electrolyte interface. More control over the surface layer can be gained when the layer is generated prior to the battery operation. Such a layer can be tailored more easily and can reduce the loss of lithium inventory considerably. In this context, water-soluble electrode binders, e.g. sodium carboxymethyl cellulose (CMC-Na) and poly(acrylic acid) (PAA), have proven themselves exceptionally useful. Since the binder is a standard component in composite electrodes anyway, its integration into the electrode fabrication process is easily accomplished.

    This thesis work investigates the parameters that govern binder distribution in elec-trode coatings, control the stability and electrochemical performance of the elec-trode and that determine the composition of the surface layer. Several commonly used electrode materials (graphite, silicon and lithium titanate) have been applied in order to study the impact of the binder on the electrode morphology and the differ-ent electrode-electrolyte interfaces. The results are correlated with the electrochemi-cal performance and with the SEI composition obtained by in-house and synchro-tron-based photoelectron spectroscopy (PES).

    The results demonstrate that the poor swellability of these water-soluble binders leads to a protection of the active material, given that the surface coverage is high and the binder evenly distributed. Although on the laboratory scale electrode formu-lations with a high binder content are common, they have little practical use in commercial devices due to the high content of inactive material. As the binder con-tent is decreased, complete surface coverage is more difficult to achieve and the binder distribution is more strongly coupled to the particle-binder interactions during the preparation process. Moreover, it is demonstrated in this thesis how these inter-actions are related to the surface area of the electrode components applied, the surface composition and the electrochemistry of the electrode. As a result of the smaller binder contents the benefits provided by CMC-Na and PAA at the electrode surface are compromised and the performance differs less distinctly from electrodes fabricated with the conventional binder, i.e. poly(vinylidene difluoride) (PVdF). Composites of alloying and conversion materials, on the other hand, typically em-ploy binders in larger amounts. Despite the frequently noted resiliency to volume expansion, which is also a positive side effect of the poor swellability of the binder in the electrolyte, the protection of the surface and the formation of a more stable interface are the major cause for the improved electrochemical behaviour, com-pared to electrodes employing PVdF binders.

    List of papers
    1. Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries
    Open this publication in new window or tab >>Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries
    2015 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, p. 141-150Article in journal (Refereed) Published
    Abstract [en]

    A comparative study of various electrode binders for graphite electrodes was conducted in a carbonate-based electrolyte with a high content of propylene carbonate (PC) as a means to evaluate anode degradation in presence of different binders. Because of its direct contact with the active material, a binder can be interpreted as an interfacial layer and as a local part of the electrolyte, the properties of which greatly depend on the interaction with the liquid electrolyte. In this work we demonstrate how a carefully chosen binder can create a specific surface environment that can protect graphite from exfoliation when the binder exhibits poor solubility in the electrolyte solvent and good surface adhesion to the active material. The exceptional stability of graphite electrodes containing poly(acrylic acid) sodium salt (PAA-Na) and carboxymethyl cellulose sodium salt (CMC-Na), respectively, in a PC-rich electrolyte is explained through the understanding of binder swelling and functionality. Interfacial resistances and electrochemical stability were investigated with impedance spectroscopy and galvanostatic cycling. Electrode morphologies and distributions of material were analysed with SEM and EDX. Evidence is presented that the surface selectivity increases with concentration of functional groups and polymer flexibility. Therefore only the less selective, stiff polymer with less functional groups, CMC-Na, provides sufficient protection at low binder contents.

    Keywords
    Binder, graphite exfoliation, CMC, propylene carbonate, SEI
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-262960 (URN)10.1016/j.electacta.2015.03.072 (DOI)000360178600019 ()
    Funder
    Swedish Research Council, 2012-3837
    Available from: 2015-09-29 Created: 2015-09-23 Last updated: 2017-12-01Bibliographically approved
    2. A stable graphite negative electrode for the lithium-sulfur battery
    Open this publication in new window or tab >>A stable graphite negative electrode for the lithium-sulfur battery
    2015 (English)In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 96, p. 17100-17103Article in journal (Refereed) Published
    National Category
    Chemical Sciences
    Identifiers
    urn:nbn:se:uu:diva-267760 (URN)10.1039/C5CC06666B (DOI)000367469400011 ()26451894 (PubMedID)
    Funder
    Swedish Research Council, 2012-3837VINNOVAStandUp
    Available from: 2015-11-26 Created: 2015-11-26 Last updated: 2017-12-30
    3. Influence of inactive electrode components on degradation phenomena in nano-Si electrodes for Li-ion batteries
    Open this publication in new window or tab >>Influence of inactive electrode components on degradation phenomena in nano-Si electrodes for Li-ion batteries
    Show others...
    2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 325, p. 513-524Article in journal (Refereed) Published
    Abstract [en]

    The electrode morphology and electrochemistry of silicon nanocomposite electrodes containing either carboxymethyl cellulose (CMC-Na) or poly(acrylic acid) (PAA) binders are examined in context of their working surface area. Using porous carbon (Ketjenblack) additives, coatings with poor adhesion properties and deep cracks were obtained. The morphology is also reflected in the electrochemical behavior under capacity-limited conditions. Mapping the differential capacity versus potential over all cycles yields detailed insights into the degradation processes and shows the onset of cell failure with the emergence of lithium-rich silicon alloys at low potentials, well before capacity fading is observed. Fading occurs faster with electrodes containing PAA binder. The surface area of the electrode components is a major cause of increased irreversible reaction and capacity fade. Synchrotron-based X-ray photoelectron spectroscopy on aged, uncycled electrodes revealed accelerated conversion of the native SiOx-layer to detrimental SiOxFy in presence of Ketjenblack. In contrast, a conventional carbon black better preserved the SiOx-layer. This effect is attributed to preferred adsorption of binder on high surface area electrode components and highlights the role of binders as 'artificial SEI-layers'. This work demonstrates that optimization of nanocomposites requires careful balancing of the surface areas and amounts of all the electrode components applied.

    Keywords
    Silicon anode, Carbon black, Binder, Artificial solid-electrolyte interface, X-ray photoelectron spectroscopy
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-307859 (URN)10.1016/j.jpowsour.2016.06.059 (DOI)000381165600059 ()
    Funder
    Swedish Research Council, 2012-3837Swedish Energy AgencyStandUp
    Available from: 2016-11-22 Created: 2016-11-22 Last updated: 2017-12-30
    4. Binder content dependence of electrochemical properties and interphase composition in Graphite:PVdF-HFP electrodes.
    Open this publication in new window or tab >>Binder content dependence of electrochemical properties and interphase composition in Graphite:PVdF-HFP electrodes.
    (English)Manuscript (preprint) (Other academic)
    Abstract
    Keywords
    Li-ion battery, binder, poly(vinylidene difluoride), photoelectron spectroscopy
    National Category
    Chemical Sciences
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317199 (URN)
    Funder
    Swedish Research CouncilStandUp
    Available from: 2017-03-11 Created: 2017-03-11 Last updated: 2018-01-03
    5. The Effects of Binders on Interface Layer Formation on Li4Ti5O12 Electrodes
    Open this publication in new window or tab >>The Effects of Binders on Interface Layer Formation on Li4Ti5O12 Electrodes
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Keywords
    Li-ion battery, Li4Ti5O12 anode, binder, interface layer, photoelectron spectroscopy
    National Category
    Chemical Sciences
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317200 (URN)
    Funder
    Swedish Research CouncilStandUpSwedish Energy Agency, Batterifonden
    Available from: 2017-03-11 Created: 2017-03-11 Last updated: 2017-12-30
    6. Water-Soluble Binders for Lithium-Ion Battery Graphite Electrodes: Slurry Rheology, Coating Adhesion and Electrochemical Performance
    Open this publication in new window or tab >>Water-Soluble Binders for Lithium-Ion Battery Graphite Electrodes: Slurry Rheology, Coating Adhesion and Electrochemical Performance
    2017 (English)In: Energy technology: generation, conversion, storage, distribution, E-ISSN 2194-4296, Vol. 5, no 11, p. 2108-2118Article in journal (Refereed) Published
    Abstract [en]

    Water-processable composite electrodes are attractive both ecologically and economically. The binders sodium carboxymethyl cellulose (CMC-Na) and poly(sodium acrylate) (PAA-Na) were shown to have improved electrochemical performance over conventional binders. In many studies, a binder content of approximately 10 wt % has been applied, which is not suitable for large-scale electrode production due to viscosity and energy-density considerations. Therefore, we examined herein three electrode formulations with binder contents of 4 wt %, namely, CMC-Na:SBR (SBR=styrene butadiene rubber), PAA-Na, and CMC-Na:PAA-Na, on both laboratory and pilot scales. The formulations were evaluated on the basis of slurry rheology, coating adhesion, and electrochemical behavior in half- and full-cells. CMC-Na:SBR composites provided the best coating adhesion, independent of the mass loading and scale, and also showed the best capacity retention after 100 cycles. Previously reported merits of better cycling efficiencies and solid–electrolyte interphase formation for graphite–PAA composites appeared to vanish upon reducing the binder content to realistic levels.

    Keywords
    Li-ion battery, Graphite, Binder, Rheology, Electrode Coating
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317257 (URN)10.1002/ente.201700200 (DOI)000417576700024 ()
    Funder
    Swedish Research Council
    Available from: 2017-03-12 Created: 2017-03-12 Last updated: 2018-03-09Bibliographically approved
    7. Analysis of the solid-electrolyte interphase of water-processed graphite electrodes by photoelectron spectroscopy
    Open this publication in new window or tab >>Analysis of the solid-electrolyte interphase of water-processed graphite electrodes by photoelectron spectroscopy
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract
    Keywords
    Li-ion battery, XPS, HAXPES, CMC-Na, PAA, graphite
    National Category
    Chemical Sciences
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-317258 (URN)
    Funder
    Swedish Research CouncilStandUp
    Available from: 2017-03-12 Created: 2017-03-12 Last updated: 2018-01-03
  • 296.
    Jeschull, Fabian
    et al.
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A stable graphite negative electrode for the lithium-sulfur battery2015In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 51, no 96, p. 17100-17103Article in journal (Refereed)
  • 297.
    Jeschull, Fabian
    et al.
    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.
    Wohlfahrt-Mehrens, Margret
    Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW).
    Memm, Michaela
    Zentrum für Sonnenenergie- und Wasserstoff-Forschung (ZSW).
    Water-Soluble Binders for Lithium-Ion Battery Graphite Electrodes: Slurry Rheology, Coating Adhesion and Electrochemical Performance2017In: Energy technology: generation, conversion, storage, distribution, E-ISSN 2194-4296, Vol. 5, no 11, p. 2108-2118Article in journal (Refereed)
    Abstract [en]

    Water-processable composite electrodes are attractive both ecologically and economically. The binders sodium carboxymethyl cellulose (CMC-Na) and poly(sodium acrylate) (PAA-Na) were shown to have improved electrochemical performance over conventional binders. In many studies, a binder content of approximately 10 wt % has been applied, which is not suitable for large-scale electrode production due to viscosity and energy-density considerations. Therefore, we examined herein three electrode formulations with binder contents of 4 wt %, namely, CMC-Na:SBR (SBR=styrene butadiene rubber), PAA-Na, and CMC-Na:PAA-Na, on both laboratory and pilot scales. The formulations were evaluated on the basis of slurry rheology, coating adhesion, and electrochemical behavior in half- and full-cells. CMC-Na:SBR composites provided the best coating adhesion, independent of the mass loading and scale, and also showed the best capacity retention after 100 cycles. Previously reported merits of better cycling efficiencies and solid–electrolyte interphase formation for graphite–PAA composites appeared to vanish upon reducing the binder content to realistic levels.

  • 298.
    Jeschull, Fabian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew J.
    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.
    Functional binders as graphite exfoliation suppressants in aggressive electrolytes for lithium-ion batteries2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 175, p. 141-150Article in journal (Refereed)
    Abstract [en]

    A comparative study of various electrode binders for graphite electrodes was conducted in a carbonate-based electrolyte with a high content of propylene carbonate (PC) as a means to evaluate anode degradation in presence of different binders. Because of its direct contact with the active material, a binder can be interpreted as an interfacial layer and as a local part of the electrolyte, the properties of which greatly depend on the interaction with the liquid electrolyte. In this work we demonstrate how a carefully chosen binder can create a specific surface environment that can protect graphite from exfoliation when the binder exhibits poor solubility in the electrolyte solvent and good surface adhesion to the active material. The exceptional stability of graphite electrodes containing poly(acrylic acid) sodium salt (PAA-Na) and carboxymethyl cellulose sodium salt (CMC-Na), respectively, in a PC-rich electrolyte is explained through the understanding of binder swelling and functionality. Interfacial resistances and electrochemical stability were investigated with impedance spectroscopy and galvanostatic cycling. Electrode morphologies and distributions of material were analysed with SEM and EDX. Evidence is presented that the surface selectivity increases with concentration of functional groups and polymer flexibility. Therefore only the less selective, stiff polymer with less functional groups, CMC-Na, provides sufficient protection at low binder contents.

  • 299.
    Jeschull, Fabian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Lindgren, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Lacey, Matthew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    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, Biology, Department of Cell and Molecular Biology, Structure and Molecular Biology.
    Influence of inactive electrode components on degradation phenomena in nano-Si electrodes for Li-ion batteries2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 325, p. 513-524Article in journal (Refereed)
    Abstract [en]

    The electrode morphology and electrochemistry of silicon nanocomposite electrodes containing either carboxymethyl cellulose (CMC-Na) or poly(acrylic acid) (PAA) binders are examined in context of their working surface area. Using porous carbon (Ketjenblack) additives, coatings with poor adhesion properties and deep cracks were obtained. The morphology is also reflected in the electrochemical behavior under capacity-limited conditions. Mapping the differential capacity versus potential over all cycles yields detailed insights into the degradation processes and shows the onset of cell failure with the emergence of lithium-rich silicon alloys at low potentials, well before capacity fading is observed. Fading occurs faster with electrodes containing PAA binder. The surface area of the electrode components is a major cause of increased irreversible reaction and capacity fade. Synchrotron-based X-ray photoelectron spectroscopy on aged, uncycled electrodes revealed accelerated conversion of the native SiOx-layer to detrimental SiOxFy in presence of Ketjenblack. In contrast, a conventional carbon black better preserved the SiOx-layer. This effect is attributed to preferred adsorption of binder on high surface area electrode components and highlights the role of binders as 'artificial SEI-layers'. This work demonstrates that optimization of nanocomposites requires careful balancing of the surface areas and amounts of all the electrode components applied.

  • 300.
    Jeschull, Fabian
    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.
    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.
    Binder content dependence of electrochemical properties and interphase composition in Graphite:PVdF-HFP electrodes.Manuscript (preprint) (Other academic)
    Abstract
3456789 251 - 300 of 839
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