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  • 1.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Åhlund, John
    Scienta.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Recent progress in high pressure analyser and experimental method development applied to liquid/solid interface studies2015Conference paper (Refereed)
  • 2.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lindgren, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ma, Yue
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Silicon anodes and electrolyte interactions2016Conference paper (Refereed)
  • 3.
    Hernández, Guiomar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Abbrent, Sabina
    Czech Acad Sci, Inst Macromol Chem.
    Kobera, Libor
    Czech Acad Sci, Inst Macromol Chem.
    Konefal, Rafal
    Czech Acad Sci, Inst Macromol Chem.
    Brus, Jiri
    Czech Acad Sci, Inst Macromol Chem.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation2019Conference paper (Other academic)
  • 4.
    Hernández, Guiomar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Abbrent, Sabina
    Czech Acad Sci, Inst Macromol Chem.
    Kobera, Libor
    Czech Acad Sci, Inst Macromol Chem.
    Konefal, Rafal
    Czech Acad Sci, Inst Macromol Chem.
    Brus, Jiri
    Czech Acad Sci, Inst Macromol Chem.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fluoroethylene Carbonate Containing Electrolytes: Origin of Poor Shelf Life and Its Mitigation2019Conference paper (Other academic)
  • 5.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Rehnlund, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Karlsruhe Inst Technol, Dept Appl Biol, Inst Appl Biosci, Kaiserstr 12, D-76131 Karlsruhe, Germany.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England.
    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.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    On the Capacity Losses Seen for Optimized Nano-Si Composite Electrodes in Li-Metal Half-Cells2019In: Advanced Energy Materials, ISSN 1614-6832, Vol. 9, no 33, article id 1901608Article in journal (Refereed)
    Abstract [en]

    While the use of silicon‐based electrodes can increase the capacity of Li‐ion batteries considerably, their application is associated with significant capacity losses. In this work, the influences of solid electrolyte interphase (SEI) formation, volume expansion, and lithium trapping are evaluated for two different electrochemical cycling schemes using lithium‐metal half‐cells containing silicon nanoparticle–based composite electrodes. Lithium trapping, caused by incomplete delithiation, is demonstrated to be the main reason for the capacity loss while SEI formation and dissolution affect the accumulated capacity loss due to a decreased coulombic efficiency. The capacity losses can be explained by the increasing lithium concentration in the electrode causing a decreasing lithiation potential and the lithiation cut‐off limit being reached faster. A lithium‐to‐silicon atomic ratio of 3.28 is found for a silicon electrode after 650 cycles using 1200 mAhg−1 capacity limited cycling. The results further show that the lithiation step is the capacity‐limiting step and that the capacity losses can be minimized by increasing the efficiency of the delithiation step via the inclusion of constant voltage delithiation steps. Lithium trapping due to incomplete delithiation consequently constitutes a very important capacity loss phenomenon for silicon composite electrodes.

  • 6.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Maibach, Julia
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Andersson, Anna M.
    Marcinek, Marek
    Niedzicki, Leszek
    Gustafsson, Torbjörn
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes2016In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 301, p. 105-112Article in journal (Refereed)
    Abstract [en]

    This report focuses on the relatively new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), and its functionality together with a silicon based composite electrode in a half-cell lithium ion battery context. LiTDI is a promising alternative to the commonly used LiPF6 salt because it does not form HF which can decompose the oxide layer on Si. The formation of a solid electrolyte interphase (SEI) as well as the development of the active Si-particles are investigated during the first electrochemical lithiation and de-lithiation. Characterizations are carried out at different state of charge with scanning electron microscopy (SEM) as well as hard x-ray photoelectron spectroscopy (HAXPES) at two different photon energies. This enables a depth resolved picture of the reaction processes and gives an idea of the chemical buildup of the SEI. The SEI is formed by solvent and LiTDI decomposition products and its composition is similar to SEI formed by other carbonate based electrolytes. The LiTDI salt or its decomposition products are not in itself reactive towards the active Si-material and no unwanted side reactions occurs with the active Si-particles. Despite some decomposition of the LiTDI salt, it is a promising alternative for electrolytes aimed towards Si-based electrodes.

  • 7.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Niedzicki, Leszek
    Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Marcinek, Marek
    Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Gustafsson, Torbjörn
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 24, p. 15758-15766Article in journal (Refereed)
    Abstract [en]

    An electrolyte based on the new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), is evaluated in combination with nano-Si composite electrodes for potential use in Li-ion batteries. The additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are also added to the electrolyte to enable an efficient SEI formation. By employing hard X-ray photoelectron spectroscopy (HAXPES), the SEI formation and the development of the active material is probed during the first 100 cycles. With this electrolyte formulation, the Si electrode can cycle at 1200 mAh g(-1) for more than 100 cycles at a coulombic efficiency of 99%. With extended cycling, a decrease in Si particle size is observed as well as an increase in silicon oxide amount. As opposed to LiPF6 based electrolytes, this electrolyte or its decomposition products has no side reactions with the active Si material. The present results further acknowledge the positive effects of SEI forming additives. It is suggested that polycarbonates and a high LiF content are favorable components in the SEI over other kinds of carbonates formed by ethylene carbonate (EC) and dimethyl carbonate (DMC) decomposition. This work thus confirms that LiTDI in combination with the investigated additives is a promising salt for Si electrodes in future Li-ion batteries.

  • 8.
    Maibach, Julia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Eriksson, Susanna K.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Ahlund, John
    Gustafsson, Torbjron
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Siegbahn, Hans
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    Rensmo, Hakan
    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.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and condensed matter physics.
    A high pressure x-ray photoelectron spectroscopy experimental method for characterization of solid-liquid interfaces demonstrated with a Li-ion battery system2015In: Review of Scientific Instruments, ISSN 0034-6748, E-ISSN 1089-7623, Vol. 86, no 4, article id 044101Article in journal (Refereed)
    Abstract [en]

    We report a methodology for a direct investigation of the solid/liquid interface using high pressure x-ray photoelectron spectroscopy (HPXPS). The technique was demonstrated with an electrochemical system represented by a Li-ion battery using a silicon electrode and a liquid electrolyte of LiClO4 in propylene carbonate (PC) cycled versus metallic lithium. For the first time the presence of a liquid electrolyte was realized using a transfer procedure where the sample was introduced into a 2 mbar N-2 environment in the analysis chamber without an intermediate ultrahigh vacuum (UHV) step in the load lock. The procedure was characterized in detail concerning lateral drop gradients as well as stability of measurement conditions over time. The X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the solid substrate and the liquid electrolyte can be observed simultaneously. The results show that the solid electrolyte interphase (SEI) composition for the wet electrode is stable within the probing time and generally agrees well with traditional UHV studies. Since the methodology can easily be adjusted to various high pressure photoelectron spectroscopy systems, extending the approach towards operando solid/liquid interface studies using liquid electrolytes seems now feasible. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.

  • 9.
    Massel, Felix
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Hikima, Kazuhiro
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Suzuki, Kota
    Hirayama, Masaaki
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Liu, Yi-Sheng
    Guo, Jinghua
    Kanno, Ryoji
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Excess lithium in transition metal layers of epitaxially grown thin film cathodes of Li2MnO3 leads to rapid loss of covalency during first battery cycle2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 47, p. 28519-28526Article in journal (Refereed)
    Abstract [en]

    We have investigated the initial-cycle battery behavior of epitaxial thin films of Li2MnO3-cathodes by employing resonant inelastic X-ray scattering (RIXS) at the O K- and Mn L3-edges. Thin films (25 nm thickness) with Li/Mn-ratios of 2.06 (stoichiometric) and 2.27 (over-stoichiometric), respectively, were epitaxially grown by pulsed laser deposition and electrochemically cycled as battery cathodes in half-cell setup, stopped at potentials for full charge (delithiation) and complete discharge (relithiation), respectively, for X-ray analysis. Using RIXS, we find that significant anionic reactions take place in both materials upon initial delithiation. However, no signatures of localized oxygen holes are found in O K-RIXS of the Li2MnO3 regardless of Li/Mn-ratio. Instead, the top of the oxygen valence band is depleted of electrons forming delocalized empty states upon delithiation. Mn L-RIXS of the over-stoichiometric cathode material shows a progressive loss of charge transfer state intensity during the first battery cycle, revealing a more rapid loss of Mn--O covalency in the over-stoichiometric material.

  • 10.
    Oltean, Gabriel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Plylahan, Nareerat
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Ihrfors, Charlotte
    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.
    Xu, Chao
    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.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Johansson, Patrik
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Towards Li-ion batteries operating at 80 °C: Ionic liquid versus conventional liquid electrolytes2018In: Batteries, Vol. 4, p. 2-6, article id 10.3390/batteries4010002Article in journal (Refereed)
    Abstract [en]

    Li-ion battery (LIB) full cells comprised of TiO2-nanotube (TiO2-nt) and LiFePO4 (LFP)electrodes and either a conventional organic solvent based liquid electrolyte or an ionic liquid basedelectrolyte have been cycled at 80 °C. While the cell containing the ionic liquid based electrolyteexhibited good capacity retention and rate capability during 100 cycles, rapid capacity fading was found for the corresponding cell with the organic electrolyte. Results obtained for TiO2-nt and LFP half-cells indicate an oxidative degradation of the organic electrolyte at 80 °C. In all, ionic liquidbased electrolytes can be used to significantly improve the performance of LIBs operating at 80 °C.

  • 11.
    Srivastav, Shruti
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    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.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Modelling the morphological background to capacity fade in Si-based lithium-ion batteries2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 258, p. 755-763Article in journal (Refereed)
    Abstract [en]

    Understanding the fundamental processes at the electrode/electrolyte interface during charge and discharge will aid the development of high-capacity Li-ion batteries (LIBs) with long lifetimes. Finite Element Methodology studies are here used to investigate the interplay between morphological changes and electrochemical performance in Si negative electrodes. A one-dimensional battery model including Solid Electrolyte Interphase (SEI) layer growth is constructed for porous Si electrodes in half-cells and used for simulating electrochemical impedance response during charge and discharge cycles. The computational results are then compared with experimental investigations. The SEI layer from the electrolyte decomposition products, different depending on the presence or absence of the fluoroethylene carbonate (FEC) additive, covers the electrode surface porous structure and is leading to an increasing polarization observed in the Nyquist plots during cycling. A continuous reformation of the SEI layer after each cycle can be observed, leading to consumption of Li-|. The electrolyte composition also results in a variation of electrode porosity, which affects the performance of the cell. A more stable porous network is formed when using the FEC additive, rendering a reduction in polarization due to improved Li diffusion inside the electrode composite.

  • 12.
    Sun, Bing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bowden, Tim
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Novel solid polymer electrolytes for large and small Li-battery applications2013Conference paper (Other academic)
  • 13.
    Sun, Bing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjorn
    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.
    At the polymer electrolyte interfaces: the role of the host material for surface decomposition mechanisms in Li-polymer batteriesManuscript (preprint) (Other academic)
    Abstract
  • 14.
    Sun, Bing
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    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.
    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.
    At the polymer electrolyte interfaces: the role of the polymer host in interphase layer formation in Li-batteries2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 26, p. 13994-14000Article in journal (Refereed)
    Abstract [en]

    In this study, X-ray photoelectron spectroscopy was applied for compositional analysis of the interphase layers formed in graphite and LiFePO4 Li-battery half cells containing solid polymer electrolytes (SPEs) consisting of poly(trimethylene carbonate) (PTMC) and LiTFSI salt. Decomposition of PTMC was observed at the anode/SPE interface, indicating different reaction products than those associated with the more conventional host material poly(ethylene oxide). Degradation mechanisms of the PTMC host material at low potentials are proposed. Compared to the LiFePO4/PEO interface, the absence of LiOH - a result of water contamination - was generally seen when using hydrophobic PTMC as the polymer host. A clear correlation of moisture content with the constitution of interphase layers in Li polymer batteries could thus be concluded. At the SPE/LiFePO4 interface, good stability was seen regardless of the polymer host materials.

  • 15.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Li, Mingkai
    Hubei Univ, Sch Mat Sci & Engn, Youyi Rd 368, Wuhan 430062, Hubei, Peoples R China.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Southwest Univ, Coll Food Sci, Chongqing 400715, Peoples R China.
    Liu, Chenjuan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhang, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting Polymer Paper-Derived Mesoporous 3D N-doped Carbon Current Collectors for Na and Li Metal Anodes: A Combined Experimental and Theoretical Study2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 41, p. 23352-23363Article in journal (Refereed)
    Abstract [en]

    Herein, the manufacturing of a free-standing N-doped mesoporous carbon (CPPY) paper by straightforward carbonization of polypyrrole-coated nanocellulose paper is described. The deposition of Na and Li on these CPPY electrodes, which also serve as current collectors, is studied using a combination of experiments and theoretical calculations. The porous CPPY electrodes gave rise to decreased current densities, which helped to prolong the life-time of the Na electrodes. While the density functional theory calculations suggest that both Na and Li should be deposited uniformly on the CPPY electrodes, the experimental results clearly show that the sodium deposition was more well-defined on the surface of the CPPY electrodes. In contrast to Li, dendrite-free Na depositions could be carried out using deposition capacities up to 12 mAh cm(-2 )and a stable Na electrode cycling performance was found during 1000 h at 1 mA cm(-2). The results suggest that it was difficult to predict the Na or Li deposition behavior merely based on calculations of the metal adsorption energies, as kinetic effects should also be taken into account. Nevertheless, the experimental results clearly show that the use of the present type of porous electrodes provides new possibilities for the development of durable Na electrodes for high-performance sodium metal batteries.

  • 16.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting polymer paper-derived separators for lithium metal batteries2018In: Energy Storage Materials, ISSN 2405-8297, Vol. 13, p. 283-292Article in journal (Refereed)
    Abstract [en]

    Overoxidised polypyrrole (PPy) paper has been employed as a mesoporous separator for lithium metal batteries (LMBs) based on its narrow pore size distribution, good thermal stability, high ionic conductivity (1.1 mS cm−1 with a LP40 electrolyte) and high electrolyte wettability. The overoxidised PPy paper was produced from a PPy/cellulose composite using a combined base and heat-treatment process, yielding a highly interrupted pyrrole molecular structure including N-containing polar groups maintaining the readily adaptable mesoporous structure of the pristine PPy paper. This well-defined pore structure gave rise to a homogeneous current distribution which significantly increased the performance of a LiFePO4|Li cell. With the overoxidised PPy separator, a symmetric Li|Li cell could be cycled reversibly for more than 600 h without any short-circuits in a LP40 electrolyte. This approach facilitates the manufacturing of well-defined separators for fundamental investigations of the influence of the separator structure on the performance of LMBs.

  • 17.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    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.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Flexible freestanding Cladophora nanocellulose paper based Si anodes for lithium-ion batteries2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 27, p. 14109-14115Article in journal (Refereed)
    Abstract [en]

    Freestanding, lightweight and flexible Si paper anodes are prepared via a straightforward paper-making process using Cladophora nano-cellulose, silicon nanoparticles and carbon nanotubes as the building blocks. The uniform Si particle distribution and strong adhesion of the Si nanoparticles to the porous, conductive and flexible nanocellulose/carbon nanotube 3D matrix yield specific capacities of up to 800 mA h g(-1) (based on the weight of whole electrode) and very good cycling performances.

  • 18.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Peng
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    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.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting Polymer Paper-Based Cathodes for High-Areal-Capacity Lithium–Organic Batteries2015In: Energy Technology, ISSN 2194-4296, Vol. 3, no 6, p. 563-569Article in journal (Refereed)
    Abstract [en]

    Conducting polymers have been considered for use as cathode materials in rechargeable lithium‐ion batteries (LIBs) since 1981 but problems with poor cycling stability, rapid self‐discharge, and low energy and power densities have so far limited their applicability. Herein it is shown that nanostructured freestanding conducting polymer composites [e.g., polypyrrole (PPy) and polyaniline (PANI)] can be used to circumvent these shortcomings. Freestanding and binder‐free PPy and cellulose‐based composites can straightforwardly be used as versatile organic cathode materials for LIBs. The composite, reinforced with chopped carbon filaments (CCFs), exhibited a large active mass loading of approximately 10 mg cm−2, an areal capacity of 1.0 mAh cm−2 (corresponding to 102 mAh g−1), and stable cycling. With an active mass loading of 4.4 mg cm−2, a capacity of 0.22 mAh cm−2 (corresponding to 58 mAh g−1) was found for current densities of 5 A g−1 yielding discharge times of approximately 40 seconds, and a capacity retention of 91 % over 100 cycles was obtained at 0.2 A g−1. The present method constitutes a straightforward approach for the manufacturing of high‐performance freestanding electroactive conducting‐polymer‐based paper‐like electrodes for use in inexpensive and sustainable, high‐performance organic LIBs.

  • 19.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    All silicon lithium-ion batteries2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lithium-ion batteries have been widely used as power supplies for portable electronic devices due to their higher gravimetric and volumetric energy densities compared to other electrochemical energy storage technologies, such as lead-acid, Ni-Cd and Ni-MH batteries. Developing a novel battery chemistry, ‘‘all silicon lithium-ion batteries’’, using lithium iron silicate as the cathode and silicon as the anode, is the primary aim of this Ph.D project. This licentiate thesis is focused on improving the performance of the silicon anode via optimization of electrolyte composition and electrode formulation. Fluoroethylene carbonate (FEC) was investigated as an electrolyte additive for silicon composite electrodes, and both the capacity retention as well as coulombic efficiency were significantly improved by introducing 10 wt% FEC into the LP40 electrolyte. This is due to the formation of a stable SEI, which mainly consisted of FEC decomposition products of LiF, -CHFOCO2-, etc. The chemical composition of the SEI was identified by synchrotron radiation based photoelectron spectroscopy. This conformal SEI prevented formation of large amounts of cracks and continues electrolyte decomposition on the silicon electrode. An alternative lithium salt, lithium 4,5-dicyano-2-trifluoromethanoimidazole (LiTDI), was studied with the silicon electrode in this thesis. The SEI formation led to a rather low 1st cycle coulombic efficiency of 44.4%, and the SEI layer was found to contain hydrocarbon, ether-type and carbonate-type species. Different to conventional composite silicon electrodes, which require heavy and expensive copper current collector, a flexible silicon electrode, consisted of only silicon nanopowder, Cladophora nanocellulose and carbon nanotube, was facilely prepared via vacuum filtration. The electrode showed good mechanical, long-term cycling as well as rate capability performance.

    List of papers
    1. Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive
    Open this publication in new window or tab >>Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive
    Show others...
    2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 7, p. 2591-2599Article in journal (Refereed) Published
    Abstract [en]

    Silicon as a negative electrode material for lithium-ion batteries has attracted tremendous attention due to its high theoretical capacity, and fluoroethylene carbonate (FEC) was used as an electrolyte additive, which significantly improved the cyclability of silicon-based electrodes in this study. The decomposition of the FEC additive was investigated by synchrotron-based X-ray photoelectron spectroscopy (PES) giving a chemical composition depth-profile. The reduction products of FEC were found to mainly consist of LiF and -CHF-OCO2-type compounds. Moreover, FEC influenced the lithium hexafluorophosphate (LiPF6) decomposition reaction and may have suppressed further salt degradation. The solid electrolyte interphase (SEI) formed from the decomposition of ethylene carbonate (EC) and diethyl carbonate (DEC), without the FEC additive present, covered surface voids and lead to an increase in polarization. However, in the presence of FEC, which degrades at a higher reduction potential than EC and DEC, instantaneously a conformal SEI was formed on the silicon electrode. This stable SEI layer sufficiently limited the emergence of large cracks and preserved the original surface morphology as well as suppressed the additional SEI formation from the other solvent. This study highlights the vital importance of how the chemical composition and morphology of the SEI influence battery performance.

    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:uu:diva-253257 (URN)10.1021/acs.chemmater.5b00339 (DOI)000353176100041 ()
    Funder
    StandUp
    Available from: 2015-05-26 Created: 2015-05-25 Last updated: 2019-12-11
    2. A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
    Open this publication in new window or tab >>A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
    Show others...
    2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 301, p. 105-112Article in journal (Refereed) Published
    Abstract [en]

    This report focuses on the relatively new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), and its functionality together with a silicon based composite electrode in a half-cell lithium ion battery context. LiTDI is a promising alternative to the commonly used LiPF6 salt because it does not form HF which can decompose the oxide layer on Si. The formation of a solid electrolyte interphase (SEI) as well as the development of the active Si-particles are investigated during the first electrochemical lithiation and de-lithiation. Characterizations are carried out at different state of charge with scanning electron microscopy (SEM) as well as hard x-ray photoelectron spectroscopy (HAXPES) at two different photon energies. This enables a depth resolved picture of the reaction processes and gives an idea of the chemical buildup of the SEI. The SEI is formed by solvent and LiTDI decomposition products and its composition is similar to SEI formed by other carbonate based electrolytes. The LiTDI salt or its decomposition products are not in itself reactive towards the active Si-material and no unwanted side reactions occurs with the active Si-particles. Despite some decomposition of the LiTDI salt, it is a promising alternative for electrolytes aimed towards Si-based electrodes.

    Keywords
    Lithium 4, 5-dicyano-2-(trifluoromethyl), imidazolide, Silicon negative electrode, Solid electrolyte interphase, Hard x-ray photoelectron spectroscopy
    National Category
    Materials Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-261159 (URN)10.1016/j.jpowsour.2015.09.112 (DOI)000365060500014 ()
    Funder
    Vinnova, P37446-1EU, FP7, Seventh Framework Programme, 312284
    Available from: 2015-08-31 Created: 2015-08-31 Last updated: 2019-12-11Bibliographically approved
    3. Flexible freestanding Cladophora nanocellulose paper based Si anodes for lithium-ion batteries
    Open this publication in new window or tab >>Flexible freestanding Cladophora nanocellulose paper based Si anodes for lithium-ion batteries
    Show others...
    2015 (English)In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 27, p. 14109-14115Article in journal (Refereed) Published
    Abstract [en]

    Freestanding, lightweight and flexible Si paper anodes are prepared via a straightforward paper-making process using Cladophora nano-cellulose, silicon nanoparticles and carbon nanotubes as the building blocks. The uniform Si particle distribution and strong adhesion of the Si nanoparticles to the porous, conductive and flexible nanocellulose/carbon nanotube 3D matrix yield specific capacities of up to 800 mA h g(-1) (based on the weight of whole electrode) and very good cycling performances.

    National Category
    Chemical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-259178 (URN)10.1039/c5ta02136g (DOI)000357257900006 ()
    Funder
    Swedish Foundation for Strategic Research , RMA-110012SweGRIDS - Swedish Centre for Smart Grids and Energy StorageCarl Tryggers foundation StandUp
    Available from: 2015-07-29 Created: 2015-07-29 Last updated: 2019-12-11
  • 20.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Non-aqueous Electrolytes and Interfacial Chemistry in Lithium-ion Batteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Lithium-ion battery (LIB) technology is currently the most promising candidate for power sources in applications such as portable electronics and electric vehicles. In today's state-of-the-art LIBs, non-aqueous electrolytes are the most widely used family of electrolytes. In the present thesis work, efforts are devoted to improve the conventional LiPF6-based electrolytes with additives, as well as to develop alternative lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI)-based electrolytes for silicon anodes. In addition, electrode/electrolyte interfacial chemistries in such battery systems are extensively investigated.

    Two additives, LiTDI and fluoroethylene carbonate (FEC), are evaluated individually for conventional LiPF6-based electrolytes combined with various electrode materials. Introduction of each of the two additives leads to improved battery performance, although the underlying mechanisms are rather different. The LiTDI additive is able to scavenge moisture in the electrolyte, and as a result, enhance the chemical stability of LiPF6-based electrolytes even at extreme conditions such as storage under high moisture content and at elevated temperatures. In addition, it is demonstrated that LiTDI significantly influences the electrode/electrolyte interfaces in NMC/Li and NMC/graphite cells. On the other hand, FEC promotes electrode/electrolyte interfacial stability via formation of a stable solid electrolyte interphase (SEI) layer, which consists of FEC-derivatives such as LiF and polycarbonates in particular.

    Moreover, LiTDI-based electrolytes are developed as an alternative to LiPF6 electrolytes for silicon anodes. Due to severe salt and solvent degradation, silicon anodes with the LiTDI-baseline electrolyte showed rather poor electrochemical performance. However, with the SEI-forming additives of FEC and VC, the cycling performance of such battery system is greatly improved, owing to a stabilized electrode/electrolyte interface.

    This thesis work highlights that cooperation of appropriate electrolyte additives is an effective yet simple approach to enhance battery performance, and in addition, that the interfacial chemistries are of particular importance to deeply understand battery behavior.

    List of papers
    1. LiTDI: A Highly Efficient Additive for Electrolyte Stabilization in Lithium-Ion Batteries
    Open this publication in new window or tab >>LiTDI: A Highly Efficient Additive for Electrolyte Stabilization in Lithium-Ion Batteries
    Show others...
    2017 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 5, p. 2254-2263Article in journal (Refereed) Published
    Abstract [en]

    The poor stability of LiPF6-based electrolytes has always been a bottleneck for conventional lithium-ion batteries. The presence of inevitable trace amounts of moisture and the operation of batteries at elevated temperatures are particularly detrimental to electrolyte stability. Here, lithium 2trifluoromethy1-4,5-dicyanoimidazole (LiTDI) is investigated as a moisture-scavenging electrolyte additive and can sufficiently suppress the hydrolysis of LiPF6. With 2 wt % LiTDI, no LiPF6 degradation can be detected after storage for 35 days, even though the water level in the electrolyte is enriched by 2000 ppm. An improved thermal stability is also obtained by employing the LiTDI additive, and the moisture-scavenging mechanism is discussed. The beneficial effects of the LiTDI additive on battery performance are demonstrated by the enhanced capacity retention of both the LiNi1/3Mn1/3Co1/3O2 (NMC)/Li and NMC/graphite cells at 55 degrees C. In particular, the increase in cell voltage hysteresis is greatly hindered when LiTDI is presented in the electrolyte. Further development of the LiTDI additive may allow the improvement of elevated-temperature batteries, as well as energy savings by reducing the amount of effort necessary for dehydration of battery components.

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2017
    National Category
    Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-319530 (URN)10.1021/acs.chemmater.6b05247 (DOI)000396639400040 ()
    Funder
    Swedish Energy Agency, 34191-1 39036-1Swedish Foundation for Strategic Research Carl Tryggers foundation StandUp
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2019-12-11
    2. The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/graphite Lithium-ion Batteries at Elevated Temperatures
    Open this publication in new window or tab >>The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/graphite Lithium-ion Batteries at Elevated Temperatures
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-320188 (URN)
    Funder
    StandUp
    Available from: 2017-04-17 Created: 2017-04-17 Last updated: 2018-01-03
    3. Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive
    Open this publication in new window or tab >>Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive
    Show others...
    2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 7, p. 2591-2599Article in journal (Refereed) Published
    Abstract [en]

    Silicon as a negative electrode material for lithium-ion batteries has attracted tremendous attention due to its high theoretical capacity, and fluoroethylene carbonate (FEC) was used as an electrolyte additive, which significantly improved the cyclability of silicon-based electrodes in this study. The decomposition of the FEC additive was investigated by synchrotron-based X-ray photoelectron spectroscopy (PES) giving a chemical composition depth-profile. The reduction products of FEC were found to mainly consist of LiF and -CHF-OCO2-type compounds. Moreover, FEC influenced the lithium hexafluorophosphate (LiPF6) decomposition reaction and may have suppressed further salt degradation. The solid electrolyte interphase (SEI) formed from the decomposition of ethylene carbonate (EC) and diethyl carbonate (DEC), without the FEC additive present, covered surface voids and lead to an increase in polarization. However, in the presence of FEC, which degrades at a higher reduction potential than EC and DEC, instantaneously a conformal SEI was formed on the silicon electrode. This stable SEI layer sufficiently limited the emergence of large cracks and preserved the original surface morphology as well as suppressed the additional SEI formation from the other solvent. This study highlights the vital importance of how the chemical composition and morphology of the SEI influence battery performance.

    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:uu:diva-253257 (URN)10.1021/acs.chemmater.5b00339 (DOI)000353176100041 ()
    Funder
    StandUp
    Available from: 2015-05-26 Created: 2015-05-25 Last updated: 2019-12-11
    4. A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
    Open this publication in new window or tab >>A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
    Show others...
    2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 301, p. 105-112Article in journal (Refereed) Published
    Abstract [en]

    This report focuses on the relatively new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), and its functionality together with a silicon based composite electrode in a half-cell lithium ion battery context. LiTDI is a promising alternative to the commonly used LiPF6 salt because it does not form HF which can decompose the oxide layer on Si. The formation of a solid electrolyte interphase (SEI) as well as the development of the active Si-particles are investigated during the first electrochemical lithiation and de-lithiation. Characterizations are carried out at different state of charge with scanning electron microscopy (SEM) as well as hard x-ray photoelectron spectroscopy (HAXPES) at two different photon energies. This enables a depth resolved picture of the reaction processes and gives an idea of the chemical buildup of the SEI. The SEI is formed by solvent and LiTDI decomposition products and its composition is similar to SEI formed by other carbonate based electrolytes. The LiTDI salt or its decomposition products are not in itself reactive towards the active Si-material and no unwanted side reactions occurs with the active Si-particles. Despite some decomposition of the LiTDI salt, it is a promising alternative for electrolytes aimed towards Si-based electrodes.

    Keywords
    Lithium 4, 5-dicyano-2-(trifluoromethyl), imidazolide, Silicon negative electrode, Solid electrolyte interphase, Hard x-ray photoelectron spectroscopy
    National Category
    Materials Chemistry Inorganic Chemistry
    Identifiers
    urn:nbn:se:uu:diva-261159 (URN)10.1016/j.jpowsour.2015.09.112 (DOI)000365060500014 ()
    Funder
    Vinnova, P37446-1EU, FP7, Seventh Framework Programme, 312284
    Available from: 2015-08-31 Created: 2015-08-31 Last updated: 2019-12-11Bibliographically approved
    5. SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries
    Open this publication in new window or tab >>SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries
    Show others...
    2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 24, p. 15758-15766Article in journal (Refereed) Published
    Abstract [en]

    An electrolyte based on the new salt, lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), is evaluated in combination with nano-Si composite electrodes for potential use in Li-ion batteries. The additives fluoroethylene carbonate (FEC) and vinylene carbonate (VC) are also added to the electrolyte to enable an efficient SEI formation. By employing hard X-ray photoelectron spectroscopy (HAXPES), the SEI formation and the development of the active material is probed during the first 100 cycles. With this electrolyte formulation, the Si electrode can cycle at 1200 mAh g(-1) for more than 100 cycles at a coulombic efficiency of 99%. With extended cycling, a decrease in Si particle size is observed as well as an increase in silicon oxide amount. As opposed to LiPF6 based electrolytes, this electrolyte or its decomposition products has no side reactions with the active Si material. The present results further acknowledge the positive effects of SEI forming additives. It is suggested that polycarbonates and a high LiF content are favorable components in the SEI over other kinds of carbonates formed by ethylene carbonate (EC) and dimethyl carbonate (DMC) decomposition. This work thus confirms that LiTDI in combination with the investigated additives is a promising salt for Si electrodes in future Li-ion batteries.

    Keywords
    lithium 4, 5-dicyano-2-(trifluoromethyl)imidazolide, fluoroethylene carbonate, vinylene carbonate, silicon negative electrode, solid electrolyte interphase, hard X-ray photoelectron spectroscopy
    National Category
    Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-299892 (URN)10.1021/acsami.6b02650 (DOI)000378584800099 ()27220376 (PubMedID)
    Funder
    VINNOVAEU, European Research Council, 312284StandUp
    Note

    Kan vara artikeln från manuskriptet http://uu.diva-portal.org/smash/record.jsf?pid=diva2:915177

    Available from: 2016-07-29 Created: 2016-07-29 Last updated: 2019-12-11
  • 21.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Abbrent, Sabina
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Kober, Libor
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Konefal, Rafal
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Brus, Jiri
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    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.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Unraveling and Mitigating the Storage Instability of Fluoroethylene Carbonate-Containing LiPF6 Electrolytes To Stabilize Lithium Metal Anodes for High-Temperature Rechargeable Batteries2019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 7, p. 4925-4935Article in journal (Refereed)
    Abstract [en]

    Implementing Li metal anodes provides the potential of substantially boosting the energy density of current Li-ion battery technology. However, it suffers greatly from fast performance fading largely due to substantial volume change during cycling and the poor stability of the solid electrolyte interphase (SEI). Fluoroethylene carbonate (FEC) is widely acknowledged as an effective electrolyte additive for improving the cycling performance of batteries consisting of electrode materials that undergo large volume changes during cycling such as Li metal. In this study, we report that while FEC can form a robust SEI on the electrode, it also deteriorates the shelf life of electrolytes containing LiPF6. The degradation mechanism of LiPF6 in FEC solutions is unraveled by liquid-and solid-state NMR. Specifically, traces of water residues induce the hydrolysis of LiPF6, releasing HF and PF5 which further trigger ring-opening of FEC and its subsequent polymerization. These reactions are significantly accelerated at elevated temperatures leading to the formation of a three-dimensional fluorinated solid polymer network. Moisture scavenger additives, such as lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), can delay the degradation reaction as well as improve the cycling stability of LiNi1/3Mn1/3Co1/3O2/Li metal batteries at 55 degrees C. This work highlights the poor shelf life of electrolytes containing FEC in combination with LiPF6 and thereby the great importance of developing proper storage methods as well as optimizing the content of FEC in practical cells.

  • 22.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William R.
    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.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/ Graphite Lithium-Ion Batteries at Elevated Temperatures2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, no 2, p. A40-A46Article in journal (Refereed)
    Abstract [en]

    The poor thermal stability of conventional LiPF6-based electrolytes is one of the major obstacles for today's lithium-ion batteries. Recently, lithium 4,5-dicyano-2-( trifluoromethyl) imidazolide (LiTDI) has demonstrated to be highly efficient in scavenging moisture from the electrolyte and thereby improving electrolyte stability. In this context, effects of the LiTDI additive on LiNi1/3Mn1/3Co1/3O2 (NMC)/graphite cells are evaluated at a temperature of 55 degrees C. With the incorporation of LiTDI, an improved cycling performance of NMC/graphite cells was achieved, and the impedance increase at the NMC/electrolyte interface was significantly mitigated. Furthermore, LiTDI exhibited a profound influence on the interfacial chemistries in the full cell, and LiTDI-derived species were found on the surfaces of both the cathode and the anode. The SEI layer formed on graphite anodes was more homogenous in morphology and consisted of larger amounts of LiF and fewer oxygen-containing species, as compared to graphite in additive-free cells. This study shows that LiTDI is a promising electrolyte additive for NMC/graphite cells operated at elevated temperatures, highlighting that the influence of the LiTDI additive is worth exploring also in other battery chemistries.

  • 23.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lindgren, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Björefors, Fredrik
    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.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 7, p. 2591-2599Article in journal (Refereed)
    Abstract [en]

    Silicon as a negative electrode material for lithium-ion batteries has attracted tremendous attention due to its high theoretical capacity, and fluoroethylene carbonate (FEC) was used as an electrolyte additive, which significantly improved the cyclability of silicon-based electrodes in this study. The decomposition of the FEC additive was investigated by synchrotron-based X-ray photoelectron spectroscopy (PES) giving a chemical composition depth-profile. The reduction products of FEC were found to mainly consist of LiF and -CHF-OCO2-type compounds. Moreover, FEC influenced the lithium hexafluorophosphate (LiPF6) decomposition reaction and may have suppressed further salt degradation. The solid electrolyte interphase (SEI) formed from the decomposition of ethylene carbonate (EC) and diethyl carbonate (DEC), without the FEC additive present, covered surface voids and lead to an increase in polarization. However, in the presence of FEC, which degrades at a higher reduction potential than EC and DEC, instantaneously a conformal SEI was formed on the silicon electrode. This stable SEI layer sufficiently limited the emergence of large cracks and preserved the original surface morphology as well as suppressed the additional SEI formation from the other solvent. This study highlights the vital importance of how the chemical composition and morphology of the SEI influence battery performance.

  • 24.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renault, Stevén
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ebadi, Mahsa
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Björklund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Guyomard, Dominique
    Univ Nantes, CNRS, UMR 6502, Inst Mat Jean Rouxel IMN, F-44322 Nantes 3, France..
    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.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    LiTDI: A Highly Efficient Additive for Electrolyte Stabilization in Lithium-Ion Batteries2017In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 5, p. 2254-2263Article in journal (Refereed)
    Abstract [en]

    The poor stability of LiPF6-based electrolytes has always been a bottleneck for conventional lithium-ion batteries. The presence of inevitable trace amounts of moisture and the operation of batteries at elevated temperatures are particularly detrimental to electrolyte stability. Here, lithium 2trifluoromethy1-4,5-dicyanoimidazole (LiTDI) is investigated as a moisture-scavenging electrolyte additive and can sufficiently suppress the hydrolysis of LiPF6. With 2 wt % LiTDI, no LiPF6 degradation can be detected after storage for 35 days, even though the water level in the electrolyte is enriched by 2000 ppm. An improved thermal stability is also obtained by employing the LiTDI additive, and the moisture-scavenging mechanism is discussed. The beneficial effects of the LiTDI additive on battery performance are demonstrated by the enhanced capacity retention of both the LiNi1/3Mn1/3Co1/3O2 (NMC)/Li and NMC/graphite cells at 55 degrees C. In particular, the increase in cell voltage hysteresis is greatly hindered when LiTDI is presented in the electrolyte. Further development of the LiTDI additive may allow the improvement of elevated-temperature batteries, as well as energy savings by reducing the amount of effort necessary for dehydration of battery components.

  • 25.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Bing
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjorn
    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.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Interface layer formation in solid polymer electrolyte lithium batteries: an XPS study2014In: JOURNAL OF MATERIALS CHEMISTRY A, ISSN 2050-7488, Vol. 2, no 20, p. 7256-7264Article in journal (Refereed)
    Abstract [en]

    The first characterization studies of the interface layer formed between a Li-ion battery electrode and a solid polymer electrolyte (SPE) are presented here. SPEs are well known for their electrochemical stability and excellent safety, and thus considered good alternatives to conventional liquid/gel electrolytes in high-energy density battery devices. This work comprises studies of solid electrolyte interphase (SEI) formation in SPE-based graphite|Li cells using X-ray photoelectron spectroscopy (XPS). SPEs based on high molecular weight poly(ethylene oxide) (PEO) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt are studied. Large amounts of LiOH are observed, and the XPS results indicate a correlation with moisture contamination in the SPEs. The water contents are quantitatively determined to be in the range of hundreds of ppm in the pure PEO as well as in the polymer electrolytes, which are prepared by a conventional SPE preparation method using different batches of PEO and at different drying temperatures. Moreover, severe salt degradation is observed at the graphite-SPE interface after the 1st discharge, while the salt is found to be more stable at the Li-SPE interface or when using LiTFSI-based liquid electrolyte equivalents.

  • 26.
    Zhou, Shengyang
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Kong, Xueying
    Zheng, Bing
    Huo, Fengwei
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Cellulose Nanofiber @ Conductive Metal–Organic Frameworks for High-Performance Flexible Supercapacitors2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 8, p. 9578-9586Article in journal (Refereed)
    Abstract [en]

    Conductive metal–organic frameworks (c-MOFs) show great potential in electrochemical energy storage thanks to their high electrical conductivity and highly accessible surface areas. However, there are significant challenges in processing c-MOFs for practical applications. Here, we report on the fabrication of c-MOF nanolayers on cellulose nanofibers (CNFs) with formation of nanofibrillar CNF@c-MOF by interfacial synthesis, in which CNFs serve as substrates for growth of c-MOF nanolayers. The obtained hybrid nanofibers of CNF@c-MOF can be easily assembled into freestanding nanopapers, demonstrating high electrical conductivity of up to 100 S cm–1, hierarchical micromesoporosity, and excellent mechanical properties. Given these advantages, the nanopapers are tested as electrodes in a flexible and foldable supercapacitor. The high conductivity and hierarchical porous structure of the electrodes endow fast charge transfer and efficient electrolyte transport, respectively. Furthermore, the assembled supercapacitor shows extremely high cycle stability with capacitance retentions of >99% after 10000 continuous charge–discharge cycles. This work provides a pathway to develop flexible energy storage devices based on sustainable cellulose and MOFs.

1 - 26 of 26
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