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  • 1.
    Aktekin, Burak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Marzano, Fernanda
    Scania CV AB.
    Zipprich, Wolfgang
    Volkswagen AG.
    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.
    Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO)—In Situ Neutron Diffraction and Performance in Li-Ion Full Cells2018Conference paper (Refereed)
    Abstract [en]

    LiNi0.5Mn1.5O4 (LNMO) is a promising spinel-type positive electrode for lithium ion batteries as it operates at high voltage and possesses high power capability. However, rapid performance degradation in full cells, especially at elevated temperatures, is a problem. There has been a considerable interest in its crystal structure as this is known to affect its electrochemical performance. LNMO can adopt a P4332 (cation ordered) or Fd-3m (cation disordered) arrangement depending on the synthesis conditions. Most of the studies in literature agree on better electrochemical performance for disordered LNMO [1], however, a clear understanding of the reason for this behaviour is still lacking. This partly arises from the fact that synthesis conditions leading to disordering also lead to oxygen deficiency, rock-salt impurities and therefore generate some Mn3+ [2]. Most commonly, X-ray diffraction is used to characterize these materials, however, accurate structural analysis is difficult due to the near identical scattering lengths of Mn and Ni. This is not the case for neutron diffraction. In this study, an in-situ neutron diffraction heating-cooling experiment was conducted on slightly Mn-rich LNMO under pure oxygen atmosphere in order to investigate relationship between disordering and oxygen deficiency. The study shows for the first time that there is no direct relationship between oxygen loss and cation disordering, as disordering starts prior to oxygen release. Our findings suggest that it is possible to obtain samples with varying degrees of ordering, yet with the same oxygen content and free from impurities. In the second part of the study, highly ordered, partially ordered and fully disordered samples have been tested in LNMO∥LTO (Li4Ti5O12) full cells at 55 °C. It is shown that differences in their performances arise only after repeated cycling, while all the samples behave similarly at the beginning of the test. The difference is believed to be related to instabilities of LNMO at higher voltages, that is, in its lower lithiation states.

    [1] A. Manthiram, K. Chemelewski, E.-S. Lee, Energy Environ. Sci. 7 (2014) 1339.

    [2] M. Kunduraci, G.G. Amatucci, J. Power Sources. 165 (2007) 359–367.

  • 2.
    Aktekin, Burak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Massel, Felix
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Ahmadi, Majid
    Delft Univ Technol, Fac Appl Sci, Kavli Inst Nanosci, NL-2628 CJ Delft, Netherlands..
    Valvo, Mario
    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. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zipprich, Wolfgang
    Volkswagen AG, D-38436 Wolfsburg, Germany..
    Marzano, Fernanda
    Scania CV AB, SE-15187 Sodertalje, Sweden..
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    How Mn/Ni Ordering Controls Electrochemical Performance in High-Voltage Spinel LiNi0.44Mn1.56O4 with Fixed Oxygen Content2020In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 3, no 6, p. 6001-6013Article in journal (Refereed)
    Abstract [en]

    The crystal structure of LiNi0.5O4 (LNMO) can adopt either low-symmetry ordered (Fd (3) over barm) or high-symmetry disordered (P4(3)32) space group depending on the synthesis conditions. A majority of published studies agree on superior electrochemical performance of disordered LNMO, but the underlying reasons for improvement remain unclear due to the fact that different thermal history of the samples affects other material properties such as oxygen content and particle morphology. In this study, ordered and disordered samples were prepared with a new strategy that renders samples with identical properties apart from their cation ordering degree. This was achieved by heat treatment of powders under pure oxygen atmosphere at high temperature with a final annealing step at 710 degrees C for both samples, followed by slow or fast cooling. Electrochemical testing showed that cation disordering improves the stability of material in charged (delithiated) state and mitigates the impedance rise in LNMO parallel to LTO (Li4Ti5O12) and LNMO parallel to Li cells. Through X-ray photoelectron spectroscopy (XPS), thicker surface films were observed on the ordered material, indicating more electrolyte side reactions. The ordered samples also showed significant changes in the Ni 2p XPS spectra, while the generation of ligand (oxygen) holes was observed in the Ni-O environment for both samples using X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). Moreover, high-resolution transmission electron microscopy (HRTEM) images indicated that the ordered samples show a decrease in ordering near the particle surface after cycling and a tendency toward rock-salt-like phase transformations. These results show that the structural arrangement of Mn/Ni (alone) has an effect on the surface and "nearsurface" properties of LNMO, particularly in delithiated state, which is likely connected to the bulk electronic properties of this electrode material.

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  • 3.
    Aktekin, Burak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Smith, Ronald I.
    Rutherford Appleton Lab, ISIS Pulsed Neutron & Muon Source, Harwell Campus, Didcot OX11 0QX, Oxon, England.
    Sörby, Magnus H.
    Inst Energy Technol, Dept Neutron Mat Characterizat, POB 40, NO-2027 Kjeller, Norway.
    Marzano, Fernanda Lodi
    Scania CV AB, SE-15187 Sodertalje, Sweden.
    Zipprich, Wolfgang
    Volkswagen AG, D-38436 Wolfsburg, Germany.
    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.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cation Ordering and Oxygen Release in LiNi0.5-xMn1.5+xO4-y (LNMO): In Situ Neutron Diffraction and Performance in Li Ion Full Cells2019In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, no 5, p. 3323-3335Article in journal (Refereed)
    Abstract [en]

    Lithium ion cells utilizing LiNi0.5Mn1.5O4 (LNMO) as the positive electrode are prone to fast capacity fading, especially when operated in full cells and at elevated temperatures. The crystal structure of LNMO can adopt a P4(3)32 (cation-ordered) or Fd (3) over barm (disordered) arrangement, and the fading rate of cells is usually mitigated when samples possess the latter structure. However, synthesis conditions leading to disordering also lead to oxygen deficiencies and rock-salt impurities and as a result generate Mn3+. In this study, in situ neutron diffraction was performed on disordered and slightly Mn-rich LNMO samples to follow cation ordering-disordering transformations during heating and cooling. The study shows for the first time that there is not a direct connection between oxygen release and cation disordering, as cation disordering is observed to start prior to oxygen release when the samples are heated in a pure oxygen atmosphere. This result demonstrates that it is possible to tune disordering in LNMO without inducing oxygen deficiencies or forming the rock-salt impurity phase. In the second part of the study, electrochemical testing of samples with different degrees of ordering and oxygen content has been performed in LNMO vertical bar vertical bar LTO (Li4Ti5O12) full cells. The disordered sample exhibits better performance, as has been reported in other studies; however, we observe that all cells behave similarly during the initial period of cycling even when discharged at a 10 C rate, while differences arise only after a period of cycling. Additionally, the differences in fading rate were observed to be time-dependent rather than dependent on the number of cycles. This performance degradation is believed to be related to instabilities in LNMO at higher voltages, that is, in its lower lithiation states. Therefore, it is suggested that future studies should target the individual effects of ordering and oxygen content. It is also suggested that more emphasis during electrochemical testing should be placed on the stability of samples in their delithiated state.

  • 4.
    Asfaw, Habtom D.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    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.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Bacsik, Zoltan
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Boosting the thermal stability of emulsion–templated polymers via sulfonation: an efficient synthetic route to hierarchically porous carbon foams2016In: ChemistrySelect, ISSN 2365-6549, Vol. 1, no 4, p. 784-792Article in journal (Refereed)
    Abstract [en]

    Hierarchically porous carbon foams with specific surface areas exceeding 600 m2 g−1 can be derived from polystyrene foams that are synthesized via water-in-oil emulsion templating. However, most styrene-based polymers lack strong crosslinks and are degraded to volatile products when heated above 400 oC. A common strategy employed to avert depolymerization is to introduce potential crosslinking sites such as sulfonic acids by sulfonating the polymers. This article unravels the thermal and chemical processes leading up to the conversion of sulfonated high internal phase emulsion polystyrenes (polyHIPEs) to sulfur containing carbon foams. During pyrolysis, the sulfonic acid groups (-SO3H) are transformed to sulfone (-C-SO2-C-) and then to thioether (-C−S-C-) crosslinks. These chemical transformations have been monitored using spectroscopic techniques: in situ IR, Raman, X-ray photoelectron and X-ray absorption near edge structure spectroscopy. Based on thermal analyses, the formation of thioether links is associated with increased thermal stability and thus a substantial decrease in volatilization of the polymers.

  • 5.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Roberts, Matthew R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Tai, Cheuk-Wai
    Stockholm University.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. DTU.
    Valvo, Mario
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nanosized LiFePO4-decorated emulsion-templated carbon foam for 3D micro batteries: a study of structure and electrochemical performance2014In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 6, no 15, p. 8804-8813Article in journal (Refereed)
    Abstract [en]

    In this article, we report a novel 3D composite cathode fabricated from LiFePO4 nanoparticles deposited conformally on emulsion-templated carbon foam by a sol–gel method. The carbon foam is synthesized via a facile and scalable method which involves the carbonization of a high internal phase emulsion (polyHIPE) polymer template. Various techniques (XRD, SEM, TEM and electrochemical methods) are used to fully characterize the porous electrode and confirm the distribution and morphology of the cathode active material. The major benefits of the carbon foam used in our work are closely connected with its high surface area and the plenty of space suitable for sequential coating with battery components. After coating with a cathode material (LiFePO4nanoparticles), the 3D electrode presents a hierarchically structured electrode in which a porous layer of the cathode material is deposited on the rigid and bicontinuous carbon foam. The composite electrodes exhibit impressive cyclability and rate performance at different current densities affirming their importance as viable power sources in miniature devices. Footprint area capacities of 1.72 mA h cm−2 at 0.1 mA cm−2 (lowest rate) and 1.1 mA h cm−2 at 6 mA cm−2(highest rate) are obtained when the cells are cycled in the range 2.8 to 4.0 V vs. lithium.

  • 6.
    Asfaw, Habtom Desta
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, C. -W
    Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691, Stockholm, Sweden.
    Valvo, Mario
    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.
    Facile synthesis of hard carbon microspheres from polyphenols for sodium-ion batteries: insight into local structure and interfacial kinetics2020In: Materials Today Energy, ISSN 2468-6069, Vol. 18, article id 100505Article in journal (Refereed)
    Abstract [en]

    Hard carbons are the most promising negative active materials for sodium ion storage. In this work, a simple synthesis approach is proposed to produce hard carbon microspheres (CMSs) (with a mean diameter of ~1.3 μm) from resorcinol-formaldehyde precursors produced via acid-catalyzed polycondensation reaction. Samples prepared at 1200, 1400, and 1500 oC showed different electrochemical behavior in terms of reversible capacity, initial coulombic efficiency (iCE), and the mechanism of sodium ion storage. The specific capacity contributions from the flat voltage profile (<0.1 V) and the sloping voltage region (0.1–1 V) showed strong correlation to the local structure (and carbonization temperature) determined by the interlayer spacing (d002) and the Raman ID/IG ratio of the hard carbons (HCs) and the rate of cycling. Electrochemical tests indicated that the HC synthesized at 1500 oC performed best with an iCE of 85–89% and a reversible capacity of 300–340 mAh g−1 at 10 mA g−1, with the majority of charge stored below 0.1 V. The d002 and the ID/IG ratio for the sample were ~3.7 Å and ~1.27, respectively, parameters indicative of the ideal local structure in HCs required for optimum performance in sodium-ion cells. In addition, galvanostatic tests on three-electrode half-cells cells revealed that sodium metal plating occurred as cycling rates were increased beyond 80 mA g−1 leading to considerably high capacity and poor coulombic efficiency, a point that must be considered in full-cell batteries. Pairing the hard CMS electrodes with Prussian white positive electrode, a proof-of-concept cell could provide a specific capacity of almost 100 mAh g−1 maintained for more than 50 cycles with a nominal voltage of 3 V.

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  • 7.
    Bedin, Michele
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Ericsson, Tore (Contributor)
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Synthetic Molecular Chemistry.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    A diiron complex as a structural model of Class 1a Robonucleotide ReductaseIn: Article in journal (Refereed)
  • 8.
    Berastegui, Pedro
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemical reactions of AgFeO2 as negative electrode in Li- and Na-ion batteries2018In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 401, p. 386-396Article in journal (Refereed)
    Abstract [en]

    AgFeO2 nanoparticles synthesized via precipitation at room temperature are investigated in Li- and Na-ion cells through electrode coatings with an alginate binder. The electrochemical reactions of AgFeO2 with Li+ and Na+ions, as well as its role as alternative negative electrode in these cell systems are carefully evaluated. Initial Li uptake causes irreversible amorphization of the AgFeO2 structure with concomitant formation of Ag0 nanoparticles. Further Li incorporation results in conversion into Fe0 nanoparticles and Li2O, together with Li-alloying of these Ag0 clusters. Similar mechanisms are also found upon Na uptake, although such processes are hindered by overpotentials, the capacity and reversibility of the reactions with Na+ ions being not comparablewith those of their Li+ counterparts. The behaviour of AgFeO2 at low potentials vs. Li+/Li displays a synergic pseudo-capacitive charge storage overlapping Li-Ag alloying/de-alloying. This feature is exploited in full cells having deeply lithiated AgFeO2 and LiFePO4 as negative and positive electrodes, respectively. These environmentally friendly iron-based full cells exhibit attractive cycle performances with ≈80% capacity retention after 1000 cycles without any electrolyte additive, average round trip efficiency of ≈89% and operational voltage of 3.0 V combined with built-in pseudo-capacitive characteristics that enable high cycling rates up to≈25C.

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  • 9.
    Bertrand, Philippe
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Doubaji, Siham
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Solhy, Solhy
    Center for Advanced Materials Université Mohammed VI Polytechnique, Lot 660-Hay Moulay Rachid Ben Guerir, Morocco.
    Valvo, Mario
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Passivation Layer and Cathodic Redox Reactions in Sodium-Ion Batteries Probed by HAXPES  2017Conference paper (Other academic)
    Abstract [en]

    In this presentation, we will present a recent example on electrode/electrolyte interfaces of materials for energy storage devices using hard X-rays photoelectron spectroscopy (HAXPES). A nondestructive analysis was made through the electrode/electrolyte interface of the first electrochemical cycle to ensure access to information not only on the active material, but also on the passivation layer formed at the electrode surface and referred to as the solid permeable interface (SPI). [1]

     

    While electrode/electrolyte study has been performed widely on Li-ion battery, not so much attention as been addressed to the Na-ion technology so far. We will focus in this presentation to NaxCo2/3Mn2/9Ni1/9O2, a novel intercalation material that could be be used as cathode in Na-ion batteries. [2] During a typical charge/discharge cycle (i.e. extraction/insertion of Na+ ions), the oxidation state of the various transition metals in the compound changes in a reversible way. A step by step analysis of the first electrochemical cycle was carried out by HAXPES providing unique information on the oxidation state of Ni, Co and Mn as well as a very interesting insight into the passivation layer present at the surface of the electrode, which results from the degradation of the electrolyte components upon reaction. This investigation shows the role of the SPI and the complexity of the redox reactions. [3]

     

     

    [1] B. Philippe, M. Hahlin, K. Edström, T. Gustafsson, H. Siegbahn, H. Rensmo, J. Electrochem. Soc, 2016, 163, A178-A191

    [2] S. Doubaji, M. Valvo, I. Saadoune, M. Dahbi, K.Edström, J. Power Sources, 2014, 266, 275-281

    [3] S. Doubaji, B. Philippe, I. Saadoune, M. Gorgoi, T. Gustafsson, A. Solhy, M. Valvo, H. Rensmo, K. Edström, ChemSusChem, 2016, 9, 97-108

  • 10.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala universitet.
    Sobkowiak, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tengstedt, Carl
    Scania CV AB.
    Valvo, Mario
    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.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Battery Performance of PEDOT Coated LiFeSO4F Cathodes with Controlled PorosityManuscript (preprint) (Other academic)
  • 11.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sobkowiak, Adam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tengstedt, Carl
    Scania CV AB, Södertälje.
    Valvo, Mario
    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.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Identifying the Electrochemical Processes in LiFeSO4F Cathodes for Lithium Ion Batteries2017In: ChemElectroChem, E-ISSN 2196-0216, Vol. 4, no 8, p. 1896-1907Article in journal (Other academic)
    Abstract [en]

    The electrochemical performance of tavorite LiFeSO4F can be considerably improved by coating the material with a conducting polymer (poly(3,4-ethylenedioxythiophene); PEDOT). Herein, the mechanisms behind the improved performance are studied systematically by careful electrochemical analysis. It is shown that the PEDOT coating improves the surface reaction kinetics for the Li-ion insertion into LiFeSO4F. For such coated materials no kinetic limitations remain, and a transition from solid state to solution-based diffusion control was observed at 0.6 mA cm−2 (circa C/2). Additionally, the quantity of PEDOT is optimized to balance the weight added by the polymer and the improved electrochemical function. Post mortem analysis shows excellent stability for the LiFeSO4F-PEDOT composite, and maintaining the electronic wiring is the most important factor for stable electrochemical cycling of LiFeSO4F. The insights and the methodology used to determine the rate-controlling steps are readily transferable to other ion-insertion-based electrodes, and the findings are important for the development of improved battery electrodes.

  • 12.
    Blidberg, Andreas
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Alfredsson, Maria
    Univ Kent, Sch Phys Sci, Canterbury CT2 7NH, Kent, England.
    Tengstedt, Carl
    Scania CV AB, SE-15187 Sodertalje, Sweden.
    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.
    Electronic changes in poly(3,4-ethylenedioxythiophene)-coated LiFeSO4F during electrochemical lithium extraction2019In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 418, p. 84-89Article in journal (Refereed)
    Abstract [en]

    The redox activity of tavorite LiFeSO4F coated with poly (3,4-ethylenedioxythiophene), i.e. PEDOT, is investigated by means of several spectroscopic techniques. The electronic changes and iron-ligand redox features of this LiFeSO4F-PEDOT composite are probed upon delithiation through X-ray absorption spectroscopy. The PEDOT coating, which is necessary here to obtain enough electrical conductivity for the electrochemical reactions of LiFeSO4F to occur, is electrochemically stable within the voltage window employed for cell cycling. Although the electronic configuration of PEDOT shows also some changes in correspondence of its reduced and oxidized forms after electrochemical conditioning in Li half-cells, its p-type doping is fully retained between 2.7 and 4.1 V with respect to Li+/Li during the first few cycles. An increased iron-ligand interaction is observed in LixFeSO4F during electrochemical lithium extraction, which appears to be a general trend for polyanionic insertion compounds. This finding is crucial for a deeper understanding of a series of oxidation phenomena in Li-ion battery cathode materials and helps paving the way to the exploration of new energy storage materials with improved electrochemical performances.

  • 13.
    Carboni, Marco
    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.
    Valvo, Mario
    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.
    Graphite for K-ion Batteries: Stability and Formation of SEI layer2018Conference paper (Other academic)
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  • 14.
    Carboni, Marco
    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.
    Valvo, Mario
    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.
    Unlocking high capacities of graphite anodes for potassium-ion batteries2019In: RSC Advances, E-ISSN 2046-2069, Vol. 9, no 36, p. 21070-21074Article in journal (Refereed)
    Abstract [en]

    Graphite is considered a promising candidate as the anode for potassium-ion batteries (KIBs). Here, we demonstrate a significant improvement in performance through the ball-milling of graphite. Electrochemical techniques show reversible K-intercalation into graphitic layers, with 65% capacity retention after 100 cycles from initial capacities and extended cycling beyond 200 cycles. Such an affinity of the graphite towards storage of K-ions is explained by means of SEM and Raman analyses. Graphite ball-milling results in a gentle mechanical exfoliation of the graphene layers and simultaneous defect formation, leading to enhanced electrochemical performance.

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  • 15.
    Doubaji, Siham
    et al.
    Univ Cadi Ayyad, FST Marrakesh, LCME, Marrakech 40000, Morocco..
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Saadoune, Ismael
    Univ Cadi Ayyad, FST Marrakesh, LCME, Marrakech 40000, Morocco.;Univ Mohammed VI Polytech, Ctr Adv Mat, Ben Guerir, Morocco..
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Mat & Energie, D-12489 Berlin, Germany..
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Solhy, Abderrahim
    Univ Mohammed VI Polytech, Ctr Adv Mat, Ben Guerir, Morocco..
    Valvo, Mario
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Passivation Layer and Cathodic Redox Reactions in Sodium-Ion Batteries Probed by HAXPES2016In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 9, no 1, p. 97-108Article in journal (Refereed)
    Abstract [en]

    The cathode material P2-NaxCo2/3Mn2/9Ni1/9O2, which could be used in Na-ion batteries, was investigated through synchrotron-based hard X-ray photoelectron spectroscopy (HAXPES). Nondestructive analysis was made through the electrode/electrolyte interface of the first electrochemical cycle to ensure access to information not only on the active material, but also on the passivation layer formed at the electrode surface and referred to as the solid permeable interface (SPI). This investigation clearly shows the role of the SPI and the complexity of the redox reactions. Cobalt, nickel, and manganese are all electrochemically active upon cycling between 4.5 and 2.0V; all are in the 4+ state at the end of charging. Reduction to Co3+, Ni3+, and Mn3+ occurs upon discharging and, at low potential, there is partial reversible reduction to Co2+ and Ni2+. A thin layer of Na2CO3 and NaF covers the pristine electrode and reversible dissolution/reformation of these compounds is observed during the first cycle. The salt degradation products in the SPI show a dependence on potential. Phosphates mainly form at the end of the charging cycle (4.5V), whereas fluorophosphates are produced at the end of discharging (2.0V).

  • 16.
    Doubaji, Siham
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. LCME, University Cadi Ayyad, Marrakech, Morocco.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Saadoune, Ismael
    LCME, University Cadi Ayyad, Marrakech, Morocco.
    Dahbi, Mohammed
    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.
    Synthesis and characterization of a new layered cathode material for sodium ion batteries2014In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 266, p. 275-281Article in journal (Refereed)
    Abstract [en]

    Owing to the high abundance of sodium and its low cost compared to lithium, sodium ion batteries have recently attracted a renewed interest as possible candidates for stationary and mobile energy storage devices. Herein, we present a new sodium ion intercalation material, Na5CO2/3Mn2/9Ni1/9O2, which has been synthesized by a sol gel route in air followed by a heat treatment at 800 degrees C for 12 h. Its structure has been studied by X-ray diffraction showing that the material crystallized in a P2-type structure (space group P6(3)/mmc). As far as the electrochemical properties of NaxCo2/3Mn2/9Ni1/9O2 as positive electrode are concerned, this compound offers a specific capacity of 110 mAh g(-1) when cycled between 2.0 and 4.2 V vs. Na+/Na. The electrodes exhibited a good capacity retention and a coulombic efficiency exceeding 99.4%, as well as a reversible discharge capacity of 140 mAh g(-1) when cycled between 2.0 and 4.5 V. These results represent a further step towards the realization of efficient sodium ion batteries, especially considering that the synthesis method proposed here is simple and cost effective and that all the electrochemical measurements were carried out without any use of additives or any optimization for both the materials and the cell components. 

  • 17.
    Feygenson, Mikhail
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics. European Spallat Source ERIC, SE-22363 Lund, Sweden; Forschungszentrum Julich, Julich Ctr Neutron Sci JCNS 1, D-52425 Julich, Germany.
    Huang, Zhongyuan
    Peking Univ, Sch Adv Mat, Shenzhen Grad Sch, Shenzhen 518055, Peoples R China..
    Xiao, Yinguo
    Peking Univ, Sch Adv Mat, Shenzhen Grad Sch, Shenzhen 518055, Peoples R China..
    Teng, Xiaowei
    Worcester Polytech Inst, Dept Chem Engn, Worcester, MA 01609 USA..
    Lohstroh, Wiebke
    Tech Univ Munich, Heinz Maier Leibnitz Zent MLZ, Lichtenbergstr 1, D-85748 Garching, Germany..
    Nandakumaran, Nileena
    Forschungszentrum Julich, Julich Ctr Neutron Sci JCNS 2, D-52425 Julich, Germany.;Forschungszentrum Julich, Peter Grunberg Inst PGI 4, D-52425 Julich, Germany..
    Neuefeind, Jörg C.
    Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA..
    Everett, Michelle
    Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA..
    Podlesnyak, Andrey A.
    Oak Ridge Natl Lab, Neutron Scattering Div, Oak Ridge, TN 37831 USA..
    Salazar-Alvarez, Germán
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Ulusoy, Seda
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Su, Yixi
    Forschungszentrum Julich, Julich Ctr Neutron Sci JCNS 4, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85747 Garching, Germany..
    Ehlert, Sascha
    Forschungszentrum Julich, Julich Ctr Neutron Sci JCNS 1, D-52425 Julich, Germany..
    Qdemat, Asma
    Forschungszentrum Julich, Julich Ctr Neutron Sci JCNS 2, D-52425 Julich, Germany.;Forschungszentrum Julich, Peter Grunberg Inst PGI 4, D-52425 Julich, Germany..
    Ganeva, Marina
    Forschungszentrum Julich, Julich Ctr Neutron Sci JCNS 4, Heinz Maier Leibnitz Zentrum MLZ, Lichtenbergstr 1, D-85747 Garching, Germany..
    Zhang, Lihua
    Brookhaven Natl Lab, Ctr Funct Nanomat, Upton, NY 11973 USA..
    Aronson, Meigan C.
    Univ British Columbia, Stewart Blusson Quantum Matter Inst, Vancouver, BC V6T 1Z4, Canada..
    Probing spin waves in Co3O4 nanoparticles for magnonics applications2024In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 16, no 3, p. 1291-1303Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of spinel nanoparticles can be controlled by synthesizing particles of a specific shape and size. The synthesized nanorods, nanodots and cubic nanoparticles have different crystal planes selectively exposed on the surface. The surface effects on the static magnetic properties are well documented, while their influence on spin waves dispersion is still being debated. Our ability to manipulate spin waves using surface and defect engineering in magnetic nanoparticles is the key to designing magnonic devices. We synthesized cubic and spherical nanoparticles of a classical antiferromagnetic material Co3O4 to study the shape and size effects on their static and dynamic magnetic proprieties. Using a combination of experimental methods, we probed the magnetic and crystal structures of our samples and directly measured spin wave dispersions using inelastic neutron scattering. We found a weak, but unquestionable, increase in exchange interactions for the cubic nanoparticles as compared to spherical nanoparticle and bulk powder reference samples. Interestingly, the exchange interactions in spherical nanoparticles have bulk-like properties, despite a ferromagnetic contribution from canted surface spins.

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  • 18.
    Gustafsson, Olof
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Baur, Christian
    Helmholtz Inst Ulm, Ulm, Germany.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fichtner, Maximilian
    Helmholtz Inst Ulm, Ulm, Germany; Karlsruhe Inst Technol, Inst Nanotechnol, Karlsruhe, Germany.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Electrochemically driven non-equilibrium phase transitions in disordered rock-salt cathode materialManuscript (preprint) (Other academic)
  • 19.
    Görlin, Mikaela
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ojwang, Dickson O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lee, Ming-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renman, Viktor
    Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway.
    Tai, Cheuk-Wai
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Aging and Charge Compensation Effects of the Rechargeable Aqueous Zinc/Copper Hexacyanoferrate Battery Elucidated Using In Situ X-ray Techniques2021In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 13, no 50, p. 59962-59974Article in journal (Refereed)
    Abstract [en]

    The zinc/copper hexacyanoferrate (Zn/CuHCF) cell has gained attention as an aqueous rechargeable zinc-ion battery (ZIB) owing to its open framework, excellent rate capability, and high safety. However, both the Zn anode and the CuHCF cathode show unavoidable signs of aging during cycling, though the underlying mechanisms have remained somewhat ambiguous. Here, we present an in-depth study of the CuHCF cathode by employing various X-ray spectroscopic techniques. This allows us to distinguish between structure-related aging effects and charge compensation processes associated with electroactive metal centers upon Zn2+ ion insertion/deinsertion. By combining high-angle annular dark-field-scanning electron transmission microscopy, X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy, and elemental analysis, we reconstruct the picture of both the bulk and the surface. First, we identify a set of previously debated X-ray diffraction peaks appearing at early stages of cycling (below 200 cycles) in CuHCF. Our data suggest that these peaks are unrelated to hypothetical ZnxCu1–xHCF phases or to oxidic phases, but are caused by partial intercalation of ZnSO4 into graphitic carbon. We further conclude that Cu is the unstable species during aging, whose dissolution is significant at the surface of the CuHCF particles. This triggers Zn2+ ions to enter newly formed Cu vacancies, in addition to native Fe vacancies already present in the bulk, which causes a reduction of nearby metal sites. This is distinct from the charge compensation process where both the Cu2+/Cu+ and Fe3+/Fe2+ redox couples participate throughout the bulk. By tracking the K-edge fluorescence using operando XAS coupled with cyclic voltammetry, we successfully link the aging effect to the activation of the Fe3+/Fe2+ redox couple as a consequence of Cu dissolution. This explains the progressive increase in the voltage of the charge/discharge plateaus upon repeated cycling. We also find that SO42– anions reversibly insert into CuHCF during charge. Our work clarifies several intriguing structural and redox-mediated aging mechanisms in the CuHCF cathode and pinpoints parameters that correlate with the performance, which will hold importance for the development of future Prussian blue analogue-type cathodes for aqueous rechargeable ZIBs

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  • 20. Kocak, Tayfun
    et al.
    Jeschull, Fabian
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Liivat, Anti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Turan, Servet
    Alternative binders for lithium iron silicate (Li2FeSiO4) cathodes2016Conference paper (Refereed)
  • 21.
    Liu, Chenjuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Valvo, Mario
    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.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Dalian Univ Technol, State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    3-D binder-free graphene foam as cathode for high capacity Li-O2 batteries2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 25, p. 9767-9773Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    To provide energy densities higher than those of conventional Li-ion batteries, a Li–O2 battery requires a cathode with high surface area to host large amounts of discharge product Li2O2. Therefore, reversible formation of discharge products needs to be investigated in Li–O2 cells containing high surface area cathodes. In this study, a binder-free oxygen electrode consisting of a 3-D graphene structure on aluminum foam, with a high defect level (ID/IG = 1.38), was directly used as the oxygen electrode in Li– O2 batteries, delivering a high capacity of about 9 *104 mA h g-1 (based on the weight of graphene) at the first full discharge using a current density of 100 mA ggraphene-1 . This performance is attributed to the 3-D porous structure of graphene foam providing both an abundance of available space for the deposition of discharge products and a high density of reactive sites for Li–O2 reactions. Furthermore, the formation of discharge products with different morphologies and their decomposition upon charge were observed by SEM. Some nanoscaled LiOH particles embedded in the toroidal Li2O2 were detected by XRD and visualized by TEM. The amount of Li2O2 formed at the end of discharge was revealed by a titration method combined with UV-Vis spectroscopy analysis. 

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  • 22.
    Lundström, Robin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala university.
    Mogensen, Ronnie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Carboni, Marco
    Valvo, Mario
    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.
    In Pursuit of Optimal Precursors for Hard Carbon Anodes2018Conference paper (Refereed)
  • 23.
    Maibach, Julia
    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.
    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.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Surface Layer Evolution on Graphite During Electrochemical Sodium-tetraglyme Co-intercalation2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 14, p. 12373-12381Article in journal (Refereed)
    Abstract [en]

    One obstacle in sodium ion batteries is the lack of suitable anode materials. As recently shown, the most common anode material of the state of the art lithium ion batteries, graphite, can be used for sodium ion storage as well, if ether based electrolyte solvents are used. These solvents cointercalate with the sodium ions leading to the highly reversible formation of ternary graphite intercalation compounds (t-GIC). In order for the solvent cointercalation to work efficiently, it is expected that only a very thin surface layer forms during electrochemical cycling. In this article, we therefore present the first dedicated study of the surface layer evolution on t-QICs using soft X-ray photoelectron spectroscopy. This technique with its inherent high surface sensitivity and low probing depth is an ideal tool to study the underlying interfacial reactions during the sodiation and desodiation of graphite. In this report, we apply this approach to graphite composite electrodes cycled in Na half cells with a 1 M sodium bis(fluorosulfonyl)imide/tetraethylene glycol dimethyl ether (NaFSI/TEG-DME) electrolyte. We have found a surface layer on the cycled electrodes, mainly composed of salt decomposition products and hydrocarbons, in line with irreversible capacity losses observed in the electrochemical cycling. Although this surface layer does not seem to block cointercalation completely, it seems to affect its efficiency resulting in a low Coulombic efficiency of the studied battery system.

  • 24.
    Meng, Qijun
    et al.
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, S-10044 Stockholm, Sweden.
    Zhang, Biaobiao
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, S-10044 Stockholm, Sweden.
    Fan, Lizhou
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, S-10044 Stockholm, Sweden.
    Liu, Haidong
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    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.
    Cuartero, Maria
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, S-10044 Stockholm, Sweden.
    de Marco, Roland
    Univ Sunshine Coast, Fac Sci Hlth Educ & Engn, 90 Sippy Dows Dr, Sippy Downs, Qld 4556, Australia;Univ Queensland, Sch Chem & Mol Biosci, Brisbane, Qld 4072, Australia.
    Crespo, Gaston A.
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, S-10044 Stockholm, Sweden.
    Sun, Licheng
    KTH Royal Inst Technol, Sch Engn Sci Chem Biotechnol & Hlth, Dept Chem, S-10044 Stockholm, Sweden;Dalian Univ Technol, DUT KTH Joint Educ & Res Ctr Mol Devices, Inst Artificial Photosynth, State Key Lab Fine Chem, Dalian 116024, Peoples R China.
    Efficient BiVO4 Photoanodes by Postsynthetic Treatment: Remarkable Improvements in Photoelectrochemical Performance from Facile Borate Modification2019In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 58, no 52, p. 19027-19033Article in journal (Refereed)
    Abstract [en]

    Water-splitting photoanodes based on semiconductor materials typically require a dopant in the structure and co-catalysts on the surface to overcome the problems of charge recombination and high catalytic barrier. Unlike these conventional strategies, a simple treatment is reported that involves soaking a sample of pristine BiVO4 in a borate buffer solution. This modifies the catalytic local environment of BiVO4 by the introduction of a borate moiety at the molecular level. The self-anchored borate plays the role of a passivator in reducing the surface charge recombination as well as that of a ligand in modifying the catalytic site to facilitate faster water oxidation. The modified BiVO4 photoanode, without typical doping or catalyst modification, achieved a photocurrent density of 3.5 mA cm(-2) at 1.23 V and a cathodically shifted onset potential of 250 mV. This work provides an extremely simple method to improve the intrinsic photoelectrochemical performance of BiVO4 photoanodes.

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  • 25.
    Naylor, Andrew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Carboni, Marco
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    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.
    Interfacial Reaction Mechanisms on Graphite Anodes for K-Ion Batteries2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 49, p. 45636-45645Article in journal (Refereed)
    Abstract [en]

    Potassium-ion (K-ion) batteries (KIBs) potentially offer numerous advantages over conventional lithium-ion batteries as a result of the high natural abundance of potassium and its lower positive charge density compared with lithium. This introduces the possibility of using K-ion in fast charging applications, in which cost effectiveness is also a major factor. Unlike in sodium-ion batteries, graphite can be used as an anode in K-ion cells, for which an extensive supply chain, electrode manufacturing infrastructure, and knowledge already exist. However, the performance of graphite anodes in K-ion cells does not meet expectations, with rapid capacity fading and poor first cycle irreversible capacities often reported. Here, we investigate the formation and composition of the solid electrolyte interphase (SEI) as well as K+ insertion in graphite anodes in KIBs. Through the use of energy-tuned synchrotron-based X-ray photoelectron spectroscopy, we make a detailed analysis at three probing depths up to ∼50 nm of graphite anodes cycled to various potentials on the first discharge-charge cycle. Extensive SEI formation from a KPF6/DEC/EC electrolyte system is found to occur at low potentials during the insertion of potassium ions into graphite. During the subsequent removal of potassium ions from the structure, the thick SEI is partially stripped from the electrode, demonstrating that the SEI layer is unstable and contributes to a significant proportion of the capacity upon both discharge and charge. With this in mind, further work is required to develop an electrolyte system with stable SEI layer formation on graphite in order to advance the KIB technology.

  • 26.
    Nkosi, Funeka P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    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.
    Dzulkurnain, Nurul A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mahun, Andrii
    Czech Acad Sci, Inst Macromol Chem, Prague 16206 6, Czech Republic.;Charles Univ Prague, Fac Sci, Dept Phys & Macromol Chem, Prague 12840 2, Czech Republic..
    Abbrent, Sabina
    Czech Acad Sci, Inst Macromol Chem, Prague 16206 6, Czech Republic..
    Brus, Jiri
    Czech Acad Sci, Inst Macromol Chem, Prague 16206 6, Czech Republic..
    Kobera, Libor
    Czech Acad Sci, Inst Macromol Chem, Prague 16206 6, Czech Republic..
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Garnet-Poly(epsilon-caprolactone-co-trimethylene carbonate) Polymer-in-Ceramic Composite Electrolyte for All-Solid-State Lithium-Ion Batteries2021In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 4, no 3, p. 2531-2542Article in journal (Refereed)
    Abstract [en]

    A composite electrolyte based on a garnet electrolyte (LLZO) and polyester-based co-polymer (80:20 epsilon-caprolactone (CL)-trimethylene carbonate, PCL-PTMC with LiTFSI salt) is prepared. Integrating the merits of both ceramic and co-polymer electrolytes is expected to address the poor ionic conductivity and high interfacial resistance in solid-state lithium-ion batteries. The composite electrolyte with 80 wt % LLZO and 20 wt % polymer (PCL-PTMC and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) at 72:28 wt %) exhibited a Li-ion conductivity of 1.31 X 10(-4) S/cm and a transference number (t(Li+)) of 0.84 at 60 degrees C, notably higher than those of the pristine PCL-PTMC electrolyte. The prepared composite electrolyte also exhibited an electrochemical stability of up to 5.4 V vs Li+/Li. The interface between the composite electrolyte and a LiFePO4 (LFP) cathode was also improved by direct incorporation of the polymer electrolyte as a binder in the cathode coating. A Li/composite electrolyte/LFP solid-state cell provided a discharge capacity of ca. 140 mAh/g and suitable cycling stability at 55 degrees C after 40 cycles. This study clearly suggests that this type of amorphous polyester-based polymers can be applied in polymer-in-ceramic composite electrolytes for the realization of advanced all-solid-state lithium-ion batteries.

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  • 27.
    Ojwang, Dickson O.
    et al.
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Grins, Jekabs
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Wardecki, Dariusz
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renman, Viktor
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Häggström, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mahmoud, Abdelfattah
    Forschungszentrum Julich, JARA FIT, Julich Ctr Neutron Sci JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, JARA FIT, Peter Grunberg Inst PGI, D-52425 Julich, Germany.;Univ Liege, Inst Phys, Inst Chem B63APTIS, LCIS GREENMAT, B-4000 Liege, Belgium..
    Hermann, Raphael P.
    Forschungszentrum Julich, JARA FIT, Julich Ctr Neutron Sci JCNS, D-52425 Julich, Germany.;Forschungszentrum Julich, JARA FIT, Peter Grunberg Inst PGI, D-52425 Julich, Germany.;Oak Ridge Natl Lab, Mat Sci & Technol Div, Oak Ridge, TN 37831 USA..
    Svensson, Gunnar
    Stockholm Univ, Arrhenius Lab, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Structure Characterization and Properties of K-Containing Copper Hexacyanoferrate2016In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 55, no 12, p. 5924-5934Article in journal (Refereed)
    Abstract [en]

    Copper hexacyanoferrate, Cu-II[Fe-III(CN)(6)](2/3)center dot nH(2)O, was synthesized, and varied amounts of IC ions were inserted via reduction by K2S2O3 (aq). Ideally, the reaction can be written as Cu-II[Fe-III(CN)(6)](2/3)-nH(2)O + 2x/3K(+) + 2x/3e(-)K(+) <-> K-2x/3 Cu-II[Fe-x(II).Fe-1-x(II),(CN)(6)](2/3)-nH(2)O. Infrared, Raman, and Mossbauer spectroscopy studies show that Fe-II is continuously reduced to Fell with increasing x, accompanied by a decrease of the a-axis of the cubic Fn (3) over barm unit cell. Elemental analysis of K by inductively coupled plasma shows that the insertion only begins when a significant fraction similar to 10% of the Fe-III, has already been reduced. Thermogravimetric analysis shows a fast exchange of water with ambient atmosphere and a total weight loss of similar to 26 wt % upon heating to 180 degrees C, above which the structure starts to decompose. The crystal structures of Cu-III[Fe-III(CN)(6)](2/3)center dot nH(2)O and K2/3Cu[Fe(CN)(6)](2/3)center dot nH(2)O were refined using synchrotron X-ray powder diffraction data. In both, one-third of the Fe(CN)(6) groups are vacant, and the octahedron around Cull is completed by water molecules. In the two structures, difference Fourier maps reveal three additional zeolitic water sites (8c, 32f, and 48g) in the center of the cavities formed by the-Cu-N-C-Fe- framework. The K-containing compound shows an increased electron density at two of these sites (32f and 48g), indicating them to be the preferred positions for the K+ ions.

  • 28.
    Oltean, Gabriel
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    On the electrophoretic and sol-gel deposition of active materials on aluminium rod current collectors for three-dimensional Li-ion micro-batteries2014In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 562, p. 63-69Article in journal (Refereed)
    Abstract [en]

    Electrophoretic deposition of titanium oxide particles, as well as sol-gel synthesis of thin films of TiO2 employing a titanium isopropoxide precursor solution, were studied as possible deposition routes for the coating of aluminium pillar current collectors intended for three-dimensional Li-ion micro-batteries. While electrophoresis of TiO2 particles was homogeneously covering the two-dimensional aluminium substrates, it was difficult to conformally coat the three-dimensional current collectors with this technique. The sol-gel approach, on the other hand, gave rise to thin and amorphous TiO2 layers on the Al rod based current collectors. The latter could be cycled for 100 cycles indicating that such straightforward sol-gel approaches may be used for the manufacturing of 3D electrodes for Li-ion micro-batteries.

  • 29.
    Oltean, Viorica-Alina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renault, Stéven
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    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.
    Sustainable Materials for Sustainable Energy Storage: Organic Na Electrodes2016In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 9, no 3, article id 142Article, review/survey (Refereed)
    Abstract [en]

    In this review, we summarize research efforts to realize Na-based organic materials for novel battery chemistries. Na is a more abundant element than Li, thereby contributing to less costly materials with limited to no geopolitical constraints while organic electrode materials harvested from biomass resources provide the possibility of achieving renewable battery components with low environmental impact during processing and recycling. Together, this can form the basis for truly sustainable electrochemical energy storage. We explore the efforts made on electrode materials of organic salts, primarily carbonyl compounds but also Schiff bases, unsaturated compounds, nitroxides and polymers. Moreover, sodiated carbonaceous materials derived from biomasses and waste products are surveyed. As a conclusion to the review, some shortcomings of the currently investigated materials are highlighted together with the major limitations for future development in this field. Finally, routes to move forward in this direction are suggested.

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  • 30. Pfeiffer, Tobias V.
    et al.
    Kedia, Puneet
    Messing, Maria E.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Schmidt-Ott, Andreas
    Precursor-Less Coating of Nanoparticles in the Gas Phase2015In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 8, no 3, p. 1027-1042Article in journal (Refereed)
    Abstract [en]

    This article introduces a continuous, gas-phase method for depositing thin metallic coatings onto (nano)particles using a type of physical vapor deposition (PVD) at ambient pressure and temperature. An aerosol of core particles is mixed with a metal vapor cloud formed by spark ablation by passing the aerosol through the spark zone using a hollow electrode configuration. The mixing process rapidly quenches the vapor, which condenses onto the core particles at a timescale of several tens of milliseconds in a manner that can be modeled as bimodal coagulation. Gold was deposited onto core nanoparticles consisting of silver or polystyrene latex, and silver was deposited onto gold nanoparticles. The coating morphology depends on the relative surface energies of the core and coating materials, similar to the growth mechanisms known for thin films: a coating made of a substance having a high surface energy typically results in a patchy coverage, while a coating material with a low surface energy will normally "wet" the surface of a core particle. The coated particles remain gas-borne, allowing further processing.

  • 31.
    Philippe, Bertrand
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Valvo, Mario
    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.
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Investigation of the Electrode/Electrolyte Interface of Fe2O3 Composite Electrodes: Li vs Na Batteries2014In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 26, no 17, p. 5028-5041Article in journal (Refereed)
    Abstract [en]

     We have investigated the properties of the electrode/electrolyte interfaces of composite electrodes based on nanostructured iron oxide cycled in Li- and Na-half cells containing analogous electrolytes (i.e., LiClO4  or NaClO4  in ethylene carbonate:diethyl carbonate (EC:DEC)). A meticulous nondestructive step-by-step analysis of the first discharge/charge cycle has been conducted via soft X-ray photoelectron spectroscopy using synchrotron radiation. In

    this way, diff erent depths were probed by varying the photon energy (hν ) for both electrochemical systems. The results of this thorough study clearly highlight the diff erences and the similarities of their respective solid electrolyte interface (SEI) layers in terms of formation, composition, structure, or thickness, as well as their conversion mechanisms. We specifi cally point out that the SEI coverage is more pronounced, and a homogeneous

    distribution rich in inorganic species exists in the case of Na, compared to the organic/inorganic layered structure observed for the Li system. The SEI formation gradually occurs during the fi rst discharge in both Li- and Na-half cells. For Na, a predeposit layer is formed directly by simple contact of the electrode with the electrolyte. Despite using similar electrolytes, the nature of the cation (Li+  or Na+ ) has signifi cant impact on the overall composition/structure of the resulting SEI.

  • 32.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    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.
    Electrodeposition of Vanadium Oxide/Manganese Oxide Hybrid Thin Films on Nanostructured Aluminum Substrates2014In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 161, no 10, p. D515-D521Article in journal (Refereed)
    Abstract [en]

    Electrodeposition of functional coatings on aluminum electrodes in aqueous solutions often is impeded by the corrosion of aluminum. In the present work it is demonstrated that electrodeposition of vanadium, oxide films on nanostructured aluminum substrates can be achieved in acidic electrolytes employing a novel strategy in which a thin interspacing layer of manganese oxide is first electrodeposited on aluminum microrod substrates. Such deposited films, which were studied using SEM, XPS, XRD, and surface enhances Raman scattering as well as chronopotentiometry, are shown to comprise a mixture of vanadium oxidation states (i.e. IV and V). As this all-electrochemical approach circumvents the problems associated with aluminum corrosion, the approach provides new possibilities for the electrochemical coating of nanostructured Al substrates with functional layers of metal oxides. The latter significantly facilitates the development of new procedures for the manufacturing of three-dimensional aluminum based electrodes for lithium ion microbatteries. (C) The Author(s) 2014. Published by ECS. All rights reserved.

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  • 33.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Ångstrom, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Stockholm University.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Electrochemical fabrication and characterization of Cu/Cu2O multi-layered micro and nanorods in Li-ion batteries2015In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 7, no 32, p. 13591-13604Article in journal (Refereed)
    Abstract [en]

    Electrodes composed of freestanding nano- and microrods composed of stacked layers of copper and cuprous oxide have been fabricated using a straightforward one-step template-assisted pulsed galvanostatic electrodeposition approach. The approach provided precise control of the thickness of each individual layer of the high-aspect-ratio rods as was verified by SEM, EDS, XRD, TEM and EELS measurements. Rods with diameters of 80, 200 and 1000 nm were deposited and the influence of the template pore size on the structure and electrochemical performance of the conversion reaction based electrodes in lithium-ion batteries was investigated. The multi-layered Cu2O/Cu nano-and microrod electrodes exhibited a potential window of more than 2 V, which was ascribed to the presence of a distribution of Cu2O (and Cu, respectively) nanoparticles with different sizes and redox potentials. As approximately the same areal capacity was obtained independent of the diameter of the multi-layered rods the results demonstrate the presence of an electroactive Cu2O layer with a thickness defined by the time domain of the measurements. It is also demonstrated that while the areal capacity of the electrodes decreased dramatically when the scan rate was increased from 0.1 to 2 mV s(-1), the capacity remained practically constant when the scan rate was further increased to 100 mV s(-1). This behaviour can be explained by assuming that the capacity is limited by the lithium ion diffusion rate though the Cu2O layer generated during the oxidation step. The electrochemical performance of present type of 3-D multi-layered rods provides new insights into the lithiation and delithiation reactions taking place for conversion reaction materials such as Cu2O.

  • 34.
    Rehnlund, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Ångström, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sahlberg, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    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.
    Electrochemical fabrication of 3D Cu/Cu2O multilayered nanostructures2015Conference paper (Other academic)
    Abstract [en]

    The possibility of engineering multilayered nanostructures and coatings with a wide variety of compositions has in the last decades attracted a great deal of scientific interest. In fact, multilayered structures with tailored properties have been investigated for solar conversion [1], the semiconductor industry [2] and tribological systems [3].Electrochemical engineering has emerged as a particularly promising technique for fabrication of nanostructured electrodes with excellent control on morphology [4]. The technique shows great promise in the copper system as Cu/Cu2O multilayers have been produced by allowing spontaneous potential oscillations to dictate the deposition [5, 6].Although this natural phenomenon provides a simple route to obtain mixedcomposition, improved control is required to obtain fine detailed multilayers. The presented study has been focused on preventing spontaneous potential oscillations to provide controlled deposition of Cu/Cu2O multilayers. In addition copper based multilayers have hereby been transported into the world of 3D electrodes via a one-step electrodeposition fabrication.

    Figure 1: Multilayered Cu/Cu2O nanopillars fabricated through electrodeposition.

    References

    1. W. Wei, et al.. Advanced Materials, 2010. 22: p. 4770-4774.

    2. G. Binasch, et al.. Physical Review B, 1989. 39: p. 4828-4830.

    3. P. E. Hovsepian, et al.. Surface and Coatings Technology, 1999. 116-119: p.727-734.

    4. K. Edström, et al.. The Electrochemical Society Interface, 2011. 20: p. 41-46.

    5. J. Eskhult, et al.. Journal of Electroanalytical Chemistry, 2006. 594: p. 35-49.6. S. Leopold, et al.. Electrochimica Acta, 2002. 47

  • 35.
    Renman, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ojwang, Dickson O.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Gómez, Cesar Pay
    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.
    Svensson, Gunnar
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Manganese Hexacyanomanganate as a Positive Electrode for Nonaqueous Li-, Na-, and K-Ion Batteries2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 36, p. 22040-22049Article in journal (Refereed)
    Abstract [en]

    K2Mn[Mn(CN)(6)] is synthesized, characterized, and evaluated as possible positive electrode material in nonaqueous Li-, Na-, and K-ion batteries. This compound belongs to the rich and versatile family of hexacyanometallates displaying distinctive structural properties, which makes it interesting for ion insertion purposes. It can be viewed as a perovskite-like compound in which CN-bridged Mn(CN)(6) octahedra form an open framework structure with sufficiently large diffusion channels able to accommodate a variety of insertion cations. By means of galvanostatic cycling and cyclic voltammetry tests in nonaqueous alkali metal half-cells, it is demonstrated that this material is able to reversibly host Li+, Na+, and K+ ions via electrochemical insertion/deinsertion within a wide voltage range. The general electrochemical features are similar for all of these three ion insertion chemistries. An in operando X-ray diffraction investigation indicates that the original monoclinic structure is transformed into a cubic one during charging (i.e., removal of cations from the host framework) and that such a process is reversible upon subsequent cell discharge and cation reuptake.

  • 36.
    Renman, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ojwang, Dickson O.
    Stockholm University, Stockholm, Sweden.
    Valvo, Mario
    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.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Svensson, Gunnar
    Stockholm University, Stockholm, Sweden.
    Structural-electrochemical relations in the aqueous copper hexacyanoferrate-zinc system examined by synchrotron X-ray diffraction2017In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 369, p. 146-153Article in journal (Refereed)
    Abstract [en]

    The storage process of Zn2+ in the Prussian blue analogue (PBA) copper hexacyanoferrate (Cu[Fe(CN)6]2/3-nH2O - CuHCF) framework structure in a context of rechargeable aqueous batteries is examined by means of in operando synchrotron X-ray diffraction. Via sequential unit-cell parameter refinements of time-resolved diffraction data, it is revealed that the step-profile of the cell output voltage curves during repeated electrochemical insertion and removal of Zn2+ in the CuHCF host structure is associated with a non-linear contraction and expansion of the unit-cell in the range 0.36 < x < 1.32 for Znx/3Cu[Fe(CN)6]2/3-nH2O. For a high insertion cation content there is no apparent change in the unit-cell contraction. Furthermore, a structural analysiswith respect to the occupancies of possible Zn2+ sites suggests that the Fe(CN)6 vacancies within the CuHCF framework play an important role in the structural-electrochemical behavior of this particular system. More specifically, it is observed that Zn2+ swaps position during electrochemical cycling, hopping between cavity sites to vacant ferricyanide sites.

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  • 37.
    Renman, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Department of Materials and Environmental Chemistry, Stockholm University.
    Gómez, Cesar Pay
    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.
    Liivat, Anti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Manganese Pyrosilicates as Novel Positive Electrode Materials for Na-Ion Batteries2018In: Sustainable Energy & Fuels, E-ISSN 2398-4902, Vol. 2, p. 941-945Article in journal (Refereed)
    Abstract [en]

    A carbon-coated pyrosilicate, Na2Mn2Si2O7/C, was synthesized and characterized for use as a new positive-electrode material for sodium ion batteries. The material consists of primary 20-80 nm particles embedded in a ≈10 nm-thick conductive carbon matrix. Reversible insertion of Na+ ions is clearly demonstrated with ≈25% of its theoretical capacity (165 mAh/g) accessible at room temperature at a low cycling rate. The material yields an average potential of 3.3 V vs. Na+/Na on charge and 2.2 V on discharge. DFT calculations predict an equilibrium potential for Na2Mn2Si2O7 in the range of 2.8-3.0 V vs. Na+/Na, with a possibility of a complete flip in the connectivity of neighboring Mn-polyhedra – from edge-sharing to disconnected and vice versa. This significant rearrangement in Mn coordination  (≈2 Å) and large volume contraction (>10%) could explain our inability to fully desodiate the material, and illustrates well the need for a new electrode design strategy beyond the conventional “down-sizing/coating” procedure.

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  • 38.
    Renman, Viktor
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Zimmermann, Iwan
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.;EPFL Valais Wallis, EPFL SCI SB MN, Rue IIndustrie 17, CH-1951 Sion, Switzerland..
    Johnsson, Mats
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden..
    Gómez, Cesar Pay
    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.
    Investigation of the Structural and Electrochemical Properties of Mn2Sb3O6CI upon Reaction with Li Ions2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 11, p. 5949-5958Article in journal (Refereed)
    Abstract [en]

    The structural and electrochemical properties of a quaternary layered compound with elemental composition Mn2Sb3O6Cl have been investigated upon reaction with lithium in Li half cells. Operando XRD was used to investigate the potential impact of this particular layered structure on the lithiation process. Although the results suggest that the material is primarily reacted through a conventional conversion mechanism, they also provide some hints that the space between the slabs may act as preferential entry points for lithium ions but not for the larger sodium ions. Cyclic voltammetry, galvanostatic cycling, HRTEM, SAED, and EELS analyses were performed to unravel the details of the reaction mechanism with the lithium ions. It is found that two pairs of reactions are mainly responsible for the reversible electrochemical cycling of this compound, namely, the alloying of Li-Sb and the conversion of MnxOy to metallic Mn with concomitant formation of Li2O upon lithium uptake. A moderate cycling stability is achieved with a gravimetric capacity of 467 mAh g(-1) after 100 cycles between 0.05 and 2.2 V vs Li+/Li despite the large particle sizes of the active material and its nonoptimal inclusion into composite coatings. The electrochemical activity of the title compound was also tested in Na half cells between 0.05 and 2 V vs Ne/Na. It was found that a prolonged period of electrochemical milling is required to fully gain access to the active material, after which the cell delivers a capacity of 350 mAh CI. These factors are demonstrated to clearly limit the ultimate performances for these electrodes.

  • 39.
    Samarasingha, Pushpaka B.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Lee, Ming-Tao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Reactive surface coating of metallic lithium and its role in rechargeable lithium metal batteries2021In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 397, article id 139270Article in journal (Refereed)
    Abstract [en]

    Realization of an outermost layer on the surface of metallic lithium is performed via reactive exposure of a thin lithium foil to a constant flow of pure O-2 gas in a controlled, airtight environment to form spontaneously a ceramic-type, Li-ion conductive film for use in rechargeable lithium metal batteries with a liquid electrolyte. This layer acts as possible intermediate 'buffer' between the underlying lithium and solid electrolyte interphase (SEI) formed in contact with the electrolyte. The impact of this oxygen-containing layer on the cycle performances of thin lithium anodes and associated surface evolution are studied here in cells having LiFePO4 as stable cathode. The influence of this protective layer on 30 mu m-thick lithium metal anodes and related effects on the electrochemical behaviour of corresponding cells are investigated with both standard LiPF6 electrolyte and lithium bis-oxalato-borate (LiBOB) as F-free alternative. Combining lithium oxide coating and LiBOB appears to play a key role in extending cell cycling and hindering dendrite formation, although a clear surface roughening of the cycled lithium is observed too. This protected lithium cycled against LiFePO4 with LiBOB provides good capacity retention at different C-rates, displaying adequate Coulombic and round-trip efficiencies and simultaneously enhancing the number of charge-discharge cycles.

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  • 40. Sharifi, Tiva
    et al.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gracia-Espino, Eduardo
    Sandstrom, Robin
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wagberg, Thomas
    Hierarchical self-assembled structures based on nitrogen-doped carbon nanotubes as advanced negative electrodes for Li-ion batteries and 3D microbatteries2015In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 279, p. 581-592Article in journal (Refereed)
    Abstract [en]

    Hierarchical structures based on carbon paper and multi-walled nitrogen-doped carbon nanotubes were fabricated and subsequently decorated with hematite nanorods to obtain advanced 3D architectures for Li-ion battery negative electrodes. The carbon paper provides a versatile metal-free 3D current collector ensuring a good electrical contact of the active materials to its carbon fiber network. Firstly, the nitrogen-doped carbon nanotubes onto the carbon paper were studied and a high footprint area capacity of 2.1 mAh cm(-2) at 0.1 mA cm(-2) was obtained. The Li can be stored in the inter-wall regions of the nanotubes, mediated by the defects formed on their walls by the nitrogen atoms. Secondly, the incorporation of hematite nanorods raised the footprint area capacity to 2.25 mAh cm(-2) at 0.1 mA cm(-2). However, the repeated conversion/de-conversion of Fe2O3 limited both coulombic and energy efficiencies for these electrodes, which did not perform as well as those including only the N-doped carbon nanotubes at higher current densities. Thirdly, long-cycling tests showed the robust Li insertion mechanism in these N-doped carbonaceous structures, which yielded an unmatched footprint area capacity enhancement up to 1.95 mAh cm(-2) after 60 cycles at 0.3 mA cm(-2) and an overall capacity of 204 mAh g(-1) referred to the mass of the entire electrode. 

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  • 41.
    Thyr, Jakob
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Valvo, Mario
    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, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solid State Physics.
    Cu2O-Coated Copper Nanopillars For Photocatalytic Water Cleaning2022Conference paper (Other academic)
    Abstract [en]

    Water pollution is a severe problem in many parts of the world. In developed countries the increased use of chemicals and urban densification has started to cause stress of previously well-functioning water systems. Advanced oxidation processes (AOPs), is a promising method for degradation of artificial organic pollutants, which are challenging to remove by conventional water treatment techniques. In AOPs hydroxyl radicals (OH•) and reactive oxygen species (O2- and O22-) which are strongly oxidizing species are generated and these subsequently react with and degrade the pollutants. To use nanostructures which are optically active in the visible part of the spectrum is attractive because it both creates a large surface area, promoting surface interface reactions, as well as enables the utilization of a large part of the solar spectrum. In this study flat copper surfaces and 3D nanostructured copper pillars are utilized as base structures. These are subjected to thermal oxidation at low temperature, for a controlled amount of time, creating thin copper oxide layers which makes them photoactive in the visible range. The formed copper oxide and its growth is analysed with SEM, XRD and Raman spectroscopy, and show the formation of Cu2O with a slight incorporation of CuO for the thickest oxide layers. Formation of CuO nano needles, protruding from the Cu2O layer, were observed in the SEM imaging. The photocatalytic performance was tested by degradation of methylene blue in aqueous solution and all of the tested systems showed quite effective performance. The highest degradation rate was seen for copper nanopillars annealed for 4 or 8 min, which exhibited 34% faster degradation than the oxidized flat sample. The study shows that simple and inexpensive thermal oxidation processes can be used to create efficient photoactive Cu2O catalysts even on semi-flat surfaces, and that nanostructuring increases the degradation rates.

  • 42.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Asfaw, Habtom Desta
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ojwang, Dickson O.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    3 - Impact of nanomaterials on Li-ion battery anodes2021In: Nanomaterials for Electrochemical Energy Storage: Challenges and Opportunities / [ed] Rinaldo Raccichini and Ulderico Ulissi, Elsevier, 2021, Vol. 19, p. 55-98Chapter in book (Other academic)
    Abstract [en]

    Anodic materials play a key role in the development of Li-ion batteries, as they influence their overall performances. Demand for improved energy and power densities, enhanced safety, and reduction in environmental impact have driven the attention toward progressive use of alternative materials with respect to state-of-the-art graphite. Developing advanced anodes requires a clear understanding and full exploitation of their underlying electrochemical mechanisms (e.g., Li insertion, Li-alloying, and conversion reactions). Nanostructured anode materials can help in achieving this goal and addressing issues to enable alternative candidates beyond graphite. The impact of nanomaterials on the development of Li-ion battery anodes is here discussed through a two-fold perspective focused on the performances enhancement and critical assessment of practical electrochemical energy storage applications of industrial relevance. A summary of the requirements to realize advanced anodes is provided at the beginning of the chapter, while geometrical aspects and dimensionality of nanostructures, together with their influence on the electrochemical properties of anodic materials and corresponding electrodes, are examined in the subsequent sections. The advantages and disadvantages of nanostructured anode materials are also discussed in detail, followed by examples of rational electrode design and composites for the fabrication of advanced nanostructured anodes. Finally, various anode materials are considered for these purposes and examples of 3D micro-battery anodes are also included.

  • 43.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Chien, Yu-Chuan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Liivat, Anti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden..
    Detecting voltage shifts and charge storage anomalies by iron nanoparticles in three-electrode cells based on converted iron oxide and lithium iron phosphate2023In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 440, article id 141747Article in journal (Refereed)
    Abstract [en]

    Noticeable voltage shifts have been observed in the charge/discharge profiles of a three-electrode cell with a lithium metal reference electrode and having a deeply lithiated iron oxide (Fe/Li2O) negative electrode galvanostatically cycled in a limited potential range against a positive LiFePO4 counterpart. The origin of such shifts has been attributed to charge storage anomalies in the Fe/Li2O nanocomposite due to characteristic reduced Fe nanoparticle sizes. These shifts also affected the extreme points of the voltage profiles of the positive electrode, which was also independently monitored. A combined evaluation of voltage profile slippages with possible changes in internal resistance and/or Li+ inventory loss, including an aimed analysis of current interruptions at the end of each lithiation/de-lithiation half-cycle to monitor the internal resistance and diffusion resistance coefficient of the Fe/Li2O electrode, has enabled a clarification of its altered charge storage. An asymmetric behaviour of the Fe/Li2O electrode during Li+ uptake/release has been revealed, highlighting a progressive, diffusion-controlled-type voltage drift at low potentials vs. Li+/Li, and an unusual tendency to slight oxidation with capacitive variations during the reverse electrochemical processes at higher voltages, instead.

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  • 44.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Doubaji, S.
    Univ Cadi Ayyad, FST Marrakech, LCME, Av A Khattabi,BP 549, Marrakech 40000, Morocco.
    Saadoune, I.
    Univ Cadi Ayyad, FST Marrakech, LCME, Av A Khattabi,BP 549, Marrakech 40000, Morocco;Mohamed VI Polytech Univ, Mat Sci & Nanoengn Dept, Lot 660 Hay Moulay Rachid, Benguerir 43150, Morocco.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pseudocapacitive charge storage properties of Na2/3Co2/3Mn2/9Ni1/9O2 in Na-ion batteries2018In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 276, p. 142-152Article in journal (Refereed)
    Abstract [en]

    The behaviour of Na2/3Co2/3Mn2/9Ni1/9O2 in composite electrodes is studied via Na half-cells utilizing a dedicated cyclic voltammetry approach. The application of increasing sweep rates enabled a detailed analysis of the red-ox peaks of this material. All peak currents due to cathodic/anodic processes demonstrated clear capacitive properties. This finding widens the picture of classical Na+ insertion/ extraction in this complex oxide, as purely diffusive processes of Na+ through its layers do not fully explain the pseudocapacitance displayed by its red-ox peaks, which are typically linked to concomitant oxidation state changes for its transition metal atoms and/or phase transitions. No phase transition was observed during in operando X-Ray diffraction upon charge to 4.2 V vs. Na+/Na, proving good structural stability for P2-NaxCo2/3Mn2/9Ni1/9O2 upon Na+ removal. The origin of such pseudocapacitive properties is likely nested in strong electrostatic interactions among the metal oxide slabs and a tendency to release Na+ from its crystallites, e.g. to form surface by-products upon air exposure. Such a reactivity induces defects (e.g. vacancies) in its lattice and charge compensation mechanisms are required to maintain an overall charge neutrality, thus ultimately influencing the electrochemical properties. Possible limiting factors for the performances of this compound in composite coatings are also discussed.

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  • 45.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Floraki, Christina
    Hellen Mediterranean Univ, Sch Engn, Dept Elect & Comp Engn, Iraklion 71410, Greece..
    Paillard, Elie
    Politecn Milan, Dept Energy, Via Lambruschini 4, I-20156 Milan, Italy..
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Vernardou, Dimitra
    Hellen Mediterranean Univ, Sch Engn, Dept Elect & Comp Engn, Iraklion 71410, Greece.;Hellen Mediterranean Univ, Inst Emerging Technol, Iraklion 71410, Greece..
    Perspectives on Iron Oxide-Based Materials with Carbon as Anodes for Li- and K-Ion Batteries2022In: Nanomaterials, E-ISSN 2079-4991, Vol. 12, no 9, article id 1436Article, review/survey (Refereed)
    Abstract [en]

    The necessity for large scale and sustainable energy storage systems is increasing. Lithium-ion batteries have been extensively utilized over the past decades for a range of applications including electronic devices and electric vehicles due to their distinguishing characteristics. Nevertheless, their massive deployment can be questionable due to use of critical materials as well as limited lithium resources and growing costs of extraction. One of the emerging alternative candidates is potassium-ion battery technology due to potassium's extensive reserves along with its physical and chemical properties similar to lithium. The challenge to develop anode materials with good rate capability, stability and high safety yet remains. Iron oxides are potentially promising anodes for both battery systems due to their high theoretical capacity, low cost and abundant reserves, which aligns with the targets of large-scale application and limited environmental footprint. However, they present relevant limitations such as low electronic conductivity, significant volume changes and inadequate energy efficiency. In this review, we discuss some recent design strategies of iron oxide-based materials for both electrochemical systems and highlight the relationships of their structure performance in nanostructured anodes. Finally, we outline challenges and opportunities for these materials for possible development of KIBs as a complementary technology to LIBs.

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  • 46.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Liivat, Anti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Eriksson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Iron-Based Electrodes Meet Water-Based Preparation, Fluorine-Free Electrolyte and Binder: A Chance for More Sustainable Lithium-Ion Batteries?2017In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 11, p. 2431-2448Article in journal (Refereed)
    Abstract [en]

    Environmentally friendly and cost-effective Li-ion cells are fabricated with abundant, non-toxic LiFePO4 cathodes and iron oxide anodes. A water-soluble alginate binder is used to coat both electrodes to reduce the environmental footprint. The critical reactivity of LiPF6-based electrolytes toward possible traces of H2O in water-processed electrodes is overcome by using a lithium bis(oxalato) borate (LiBOB) salt. The absence of fluorine in the electrolyte and binder is a cornerstone for improved cell chemistry and results in stable battery operation. A dedicated approach to exploit conversion-type anodes more effectively is also disclosed. The issue of large voltage hysteresis upon conversion/de-conversion is circumvented by operating iron oxide in a deeply lithiated Fe/Li2O form. Li-ion cells with energy efficiencies of up to 92% are demonstrated if LiFePO4 is cycled versus such anodes prepared through a prelithiation procedure. These cells show an average energy efficiency of approximately 90.66% and a mean Coulombic efficiency of approximately 99.65% over 320 cycles at current densities of 0.1, 0.2 and 0.3 mAcm(-2). They retain nearly 100% of their initial discharge capacity and provide an unmatched operation potential of approximately 2.85 V for this combination of active materials. No occurrence of Li plating was detected in three-electrode cells at charging rates of approximately 5C. Excellent rate capabilities of up to approximately 30C are achieved thanks to the exploitation of size effects from the small Fe nanoparticles and their reactive boundaries.

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  • 47.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Liivat, Anti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Eriksson, Henrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Department of Materials and Environmental Chemistry - Arrhenius Laboratory, Stockholm University.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Towards more environmentally friendly iron-based Li-ion batteries2017Conference paper (Other academic)
  • 48.
    Valvo, Mario
    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.
    Lafont, Ugo
    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.
    Towards more sustainable negative electrodes in Na-ion batteries via nanostructured iron oxide2014In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 245, p. 967-978Article in journal (Refereed)
    Abstract [en]

    Na-ion technology could emerge as an alternative to Li-ion batteries due to limited costs and vast availability of sodium, as well as its similar chemistry. Several Na-rich compounds have been proposed as positive electrodes, whereas suitable negative counterparts have not been found yet. Nanostructured iron oxide is reported here for the first time as a potentially viable negative electrode for Na-ion cells based on conventional electrolytes and composite coatings with carboxymethyl cellulose. Electrochemical reactions of Na+ and Li+ ions with nanostructured Fe2O3 are analysed and compared. Initial sodiation of Fe2O3 yields a sloping profile in a voltage range characteristic for oxide conversion, which instead generates a typical plateau upon lithiation. Application of such earth-abundant, nontoxic material in upcoming Na-ion batteries is potentially groundbreaking, since it offers important advantages, namely: i. simple and cost-effective synthesis of Fe2O3 nanostructures at low temperatures; ii. cheaper and more sustainable cell fabrication with higher energy densities, e.g., use of natural, water-soluble binders, as well as Al for both current collectors; iii. electrochemical performances with specific gravimetric capacities exceeding 400 mAh g(-1) at 40 mA g(-1), accompanied by decent specific volumetric energy densities, e.g., approximate to 1.22 Wh cm(-3), provided that cycle inefficiencies and long-term durability are addressed.

  • 49.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Lindgren, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Check-Wai, Tai
    Arrhenius Laboratory, Department of Materials and Environmental Chemistry, Stockholm.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Insight into the processes controlling the electrochemical reactions of nanostructured iron oxide electrodes in Li- and Na-half cells2016In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 194, p. 74-83Article in journal (Refereed)
    Abstract [en]

    The kinetics and the processes governing the electrochemical reactions of various types of iron oxide nanostructures (i.e., nanopowders, nanowires and thin-films) have been studied via cyclic voltammetry in parallel with Li- and Na-half cells containing analogous electrolytes (Li+/Na+, ClO4 in EC:DEC). The particular features arising from each electrode architecture are discussed and compared to shed light on the associated behaviour of the reacting nanostructured active materials. The influence of their characteristic structure, texture and electrical wiring on the overall conversion reaction upon their respective lithiation and sodiation has been analyzed carefully. The limiting factors existing for this reaction upon uptake of Li+ and Na+ ions are highlighted and the related issues in both systems are addressed. The results of this investigation clearly prove that the conversion of iron oxide into metallic Fe and Na2O is severely impeded compared to its analogous process upon lithiation, independently of the type of nanostructure involved in such reaction. The diffusion mechanisms of the different ions (i.e., Li+vs. Na+) through the phases formed upon conversion, as well as the influence of various interfaces on the resulting reaction, appear to pose further constraints on an efficient use of these compounds.

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  • 50.
    Valvo, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Rehnlund, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lafont, Ugo
    Hahlin, Maria
    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.
    The impact of size effects on the electrochemical behaviour of Cu2O-coated Cu nanopillars for advanced Li-ion microbatteries2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 25, p. 9574-9586Article in journal (Refereed)
    Abstract [en]

    The generation of a distribution of nanoparticles upon conversion reaction of thin Cu2O layers is demonstrated to produce a wide electrochemical potential window, as well as a distinctive capacity increase in large area three-dimensional electrodes. Cu nanopillars with a 10-15 nm Cu2O coating containing traces of nanocrystattine Fe2O3 yield capacities up to 0.265 mA h cm(-2) (at 61 mA g(-1)), excellent cycling for more than 300 cycles and an electroactive potential window larger than 2 V. due to the size effects caused by the various Cu/Cu2O nanopartictes formed during conversion/deconversion. These 3D Li-ion battery electrodes based on etectrodeposited Cu nanopillars spontaneously coated with a Cu2O layer are compatible with current densities of 16 A g(-1) (i.e. 61 C rates) after aerosol-assisted infiltration with an iron acetate solution followed by low-temperature pyrolysis. The capacity of the composite material increases by 67% during 390 cycles due to the growth of the electroactive area during the electrochemical milling of Cu2O forced by its repeated conversion/de-conversion. The latter generates a distribution of nanoparticles with different sizes and redox potentials, which explains the broad potential window, as well as the significant capacity contribution from double layer charging. These 3D electrodes should be well-suited for Li-ion microbatteries and Li-ion batteries in general, since they combine high capacities per footprint area with excellent power capabilities. More importantly, such electrodes grant access to fundamental understanding of the electrochemical behaviour of these active materials providing new insights into both conversion mechanisms and nanostructured interfaces more in general.

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