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  • 1.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Sahoo, Satyaprakash
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Gaur, Anand P. S.
    Katiyar, Ram S.
    Guinel, Maxime J-F
    WO3 nano-ribbons: their phase transformation from tungstite (WO3·H2O) to tungsten oxide (WO3)2014In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 49, no 17, p. 5899-5909Article in journal (Refereed)
  • 2.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Guinel, Maxime J-F.
    University of Puerto Rico.
    Synthesis of tungsten oxide nanoparticles using a hydrothermal method at ambient pressure2014In: Journal of Materials Research, ISSN 0884-2914, E-ISSN 2044-5326, Vol. 29, no 13, p. 1424-1430Article in journal (Refereed)
  • 3.
    Ahmadi, Majid
    et al.
    University of Puerto Rico.
    Younesi, Reza
    Technical University of Denmark.
    Vegge, Tejs
    Technical University of Denmark.
    Guinel, Maxime J-F
    University of Puerto Rico.
    Nickel oxide crystalline nano flakes: synthesis, characterization and their use as anode in lithium-ion batteries2014In: Materials Research Express, ISSN 2053-1591, Vol. 1, no 2, p. 025501-Article in journal (Refereed)
  • 4.
    Aktekin, Burak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nordh, Tim
    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.
    Tengstedt, Carl
    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.
    Understanding the Capacity Loss in LiNi0.5Mn1.5O4-Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 21, p. 11234-11248Article in journal (Refereed)
    Abstract [en]

    The high-voltage spinel LiNi0.5Mn1.5O4, (LNMO) is an attractive positive electrode because of its operating voltage around 4.7 V (vs Li/Li+) and high power capability. However, problems including electrolyte decomposition at high voltage and transition metal dissolution, especially at elevated temperatures, have limited its potential use in practical full cells. In this paper, a fundamental study for LNMO parallel to Li4Ti5O12 (LTO) full cells has been performed to understand the effect of different capacity fading mechanisms contributing to overall cell failure. Electrochemical characterization of cells in different configurations (regular full cells, back-to-back pseudo-full cells, and 3-electrode full cells) combined with an intermittent current interruption technique have been performed. Capacity fade in the full cell configuration was mainly due to progressively limited lithiation of electrodes caused by a more severe degree of parasitic reactions at the LTO electrode, while the contributions from active mass loss from LNMO or increases in internal cell resistance were minor. A comparison of cell formats constructed with and without the possibility of cross-talk indicates that the parasitic reactions on LTO occur because of the transfer of reaction products from the LNMO side. The efficiency of LTO is more sensitive to temperature, causing a dramatic increase in the fading rate at 55 degrees C. These observations show how important the electrode interactions (cross-talk) can be for the overall cell behavior. Additionally, internal resistance measurements showed that the positive electrode was mainly responsible for the increase of resistance over cycling, especially at 55 degrees C. Surface characterization showed that LNMO surface layers were relatively thin when compared with the solid electrolyte interphase (SEI) on LTO. The SEI on LTO does not contribute significantly to overall internal resistance even though these films are relatively thick. X-ray absorption near-edge spectroscopy measurements showed that the Mn and Ni observed on the anode were not in the metallic state; the presence of elemental metals in the SEI is therefore not implicated in the observed fading mechanism through a simple reduction process of migrated metal cations.

  • 5.
    Aktekin, Burak
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lacey, Matthew
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nordh, Tim
    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.
    Tengstedt, Carl
    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.
    Understanding the Capacity Loss in LiNi0.5Mn1.5O4 - Li4Ti5O12 Lithium-Ion Cells at Ambient and Elevated Temperatures2017Conference paper (Refereed)
    Abstract [en]

    The high voltage spinel LiNi0.5Mn1.5O(LNMO) is an attractive positive electrode due to its operating voltage around 4.7 V (vs. Li/Li+) arising from the Ni2+/Ni4+ redox couple. In addition to high voltage operation, a second advantage of this material is its capability for fast lithium diffusion kinetics through 3-D transport paths in the spinel structure. However, the electrode material is prone to side reactions with conventional electrolytes, including electrolyte decomposition and transition metal dissolution, especially at elevated temperatures1. It is important to understand how undesired reactions originating from the high voltage spinel affect the aging of different cell components and overall cycle life. Half-cells are usually considered as an ideal cell configuration in order to get information only from the electrode of interest. However, this cell configuration may not be ideal to understand capacity fading for long-term cycling and the assumption of ‘stable’ lithium negative electrode may not be valid, especially at high current rates2. Also, among the variety of capacity fading mechanisms, the loss of “cyclable” lithium from the positive electrode (or gain of lithium from electrolyte into the negative electrode) due to side reactions in a full-cell can cause significant capacity loss. This capacity loss is not observable in a typical half-cell as a result of an excessive reserve of lithium in the negative electrode.

    In a full-cell, it is desired that the negative electrode does not contribute to side reactions in a significant way if the interest is more on the positive side. Among candidates on the negative side, Li4Ti5O12 (LTO) is known for its stability since its voltage plateau (around 1.5 V vs. Li/Li+) is in the electrochemical stability window of standard electrolytes and it shows a very small volume change during lithiation. These characteristics make the LNMO-LTO system attractive for a variety of applications (e.g. electric vehicles) but also make it a good model system for studying aging in high voltage spinel-based full cells.

    In this study, we aim to understand the fundamental mechanisms resulting in capacity fading for LNMO-LTO full cells both at room temperature and elevated temperature (55°C). It is known that electrode interactions occur in this system due to migration of reaction products from LNMO to the LTO side3, 4. For this purpose, three electrode cells have been cycled galvanostatically with short-duration intermittent current interruptionsin order to observe internal resistance for both LNMO and LTO electrodes in a full cell, separately. Change of voltage curves over cycling has also been observed to get an insight into capacity loss. For comparison purposes, back-to-back cells (a combination of LNMO and LTO cells connected electrically by lithium sides) were also tested similarly. Post-cycling of harvested electrodes in half cells was conducted to determine the degree of capacity loss due to charge slippage compared to other aging factors. Surface characterization of LNMO as well as LTO electrodes after cycling at room temperature and elevated temperature has been done via SEM, XPS, HAXPES and XANES.

    References

    1. A. Kraytsberg, Y. Ein-Eli, Adv. Energy Mater., vol. 2, pp. 922–939, 2012.

    2. Aurbach, D., Zinigrad, E., Cohen, Y., & Teller, H. Solid State Ionics, 148(3), 405-416, 2002.

    3. Li et al., Journal of The Electrochemical Society, 160 (9) A1524-A1528, 2013.

    4. Aktekin et al., Journal of The Electrochemical Society 164.4: A942-A948. 2017.

    5. Lacey, M. J., ChemElectroChem. Accepted Author Manuscript. doi:10.1002/celc.201700129, 2017. 

  • 6.
    Aktekin, Burak
    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.
    Zipprich, Wolfgang
    Volkswagen AG, Wolfsburg, Germany..
    Tengstedt, Carl
    Scania CV AB, Södertalje..
    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.
    The Effect of the Fluoroethylene Carbonate Additive in LiNi0.5Mn1.5O4 - Li4Ti5O12 Lithium-Ion Cells2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 4, p. A942-A948Article in journal (Refereed)
    Abstract [en]

    The effect of the electrolyte additive fluoroethylene carbonate (FEC) for Li-ion batteries has been widely discussed in literature in recent years. Here, the additive is studied for the high-voltage cathode LiNi0.5Mn1.5O4 (LNMO) coupled to Li4Ti5O12 (LTO) to specifically study its effect on the cathode side. Electrochemical performance of full cells prepared by using a standard electrolyte (LP40) with different concentrations of FEC (0, 1 and 5 wt%) were compared and the surface of cycled positive electrodes were analyzed by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results show that addition of FEC is generally of limited use for this battery system. Addition of 5 wt% FEC results in relatively poor cycling performance, while the cells with 1 wt% FEC showed similar behavior compared to reference cells prepared without FEC. SEM and XPS analysis did not indicate the formation of thick surface layers on the LNMO cathode, however, an increase in layer thickness with increased FEC content in the electrolyte could be observed. XPS analysis on LTO electrodes showed that the electrode interactions between positive and negative electrodes occurred as Mn and Ni were detected on the surface of LTO already after 1 cycle. (C) The Author(s) 2017. Published by ECS. All rights reserved.

  • 7.
    Alimadadi, H.
    et al.
    Chalmers University of Technology.
    Ahmadi, M.
    University of Tehran.
    Aliofkhazraei, M.
    Tarbiat Modares University.
    Younesi, S.R.
    Royal Institute of Technology (KTH).
    Corrosion properties of electrodeposited nanocrystalline and amorphous patterned Ni–W alloy2009In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, ISSN 0261-3069, Vol. 30, no 4, p. 1356-1361Article in journal (Refereed)
    Abstract [en]

    Nickel-tungsten with satisfactory corrosion properties is a promising alloy to replace hard chromium. Relatively high adhesion between copper substrate and electrodeposited Ni-W alloy results in patterned morphology due to crack formation. In this work, corrosion resistance of patterned Ni–W alloys comprising 0-26 at.%.W were studied by potentiodynamic polarization and EIS in a medium containing Cl-. It is shown that corrosion resistance of single phase Ni-W is superior to amorphous and dual phase coated layers. It is also found that crack density is the dominant affecting factor on corrosion resistance of amorphous Ni-W alloys.

  • 8.
    Andersson, M.
    et al.
    YKI Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden.
    Hillerström, A.
    YKI Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden.
    Svensk, A.
    YKI Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden.
    Younesi, S. R.
    YKI Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden.
    Sjöström, E.
    Blute, I.
    Kjellin, M.
    Kizilng, J.
    Kronberg, B.
    Oldgren, J.
    Hansson, A.
    Sjöstrand, S.
    A New Class of Labile Surfactants that Break Down to Non-surface Active Products upon Heating or after a Pre-set Time, without the Need for a pH Change2007In: Tenside Surfactants Detergents, ISSN 0932-3414, E-ISSN 2195-8564, Vol. 44, no 6, p. 366-372Article in journal (Refereed)
    Abstract [en]

    A new class of labile surfactants that break down at a controllable rate without the need for a change in pH will be presented. The invention has been patented by YKI Institute for Surface Chemistry, and is based on use of β-keto acids or their salts as surface-active compounds. These surfactants spontaneously break down through decarboxylation, to form an oil-like ketone and CO 2/HCO 3 -/CO 32 - depending on pH. The rate of breakdown can be controlled within a wide range by temperature or by certain additives, but, unlike most cleavable surfactants, a change in pH is not needed. Furthermore the surfactants can be conveniently activated from a stabile precursor just before use, and one (of many possible) precursors of this kind is already available on the industrial scale in the form of a wellknown chemical that is FDA-approved in other, non-surfactant, applications. The compound in question, alkyl ketene dimer (AKD), is produced in large scale by a number of large chemical producers today, and used for hydrophobization of paper. The present article gives an overview of the surfactant chemistry, with focus on recent studies of the kinetics of activation of the surfactant precursor and breakdown kinetics of the labile surfactant at different conditions. Furthermore, possible industrial applications of the surfactant will be discussed, with one example taken from a recent feasibility study performed within the car washing area. © Carl Hanser Publisher.

  • 9.
    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.

  • 10.
    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.

  • 11.
    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, Structural Chemistry. St. Andrews.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. DTU.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Emulsion-templated bicontinuous carbon network electrodes for use in 3D microstructured batteries2013In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 1, no 44, p. 13750-13758Article in journal (Refereed)
    Abstract [en]

    High surface area carbon foams were prepared and characterized for use in 3D structured batteries. Twopotential applications exist for these foams: firstly as an anode and secondly as a current collector supportfor electrode materials. The preparation of the carbon foams by pyrolysis of a high internal phase emulsionpolymer (polyHIPE) resulted in structures with cage sizes of 25 mm and a surface area enhancement pergeometric area of approximately 90 times, close to the optimal configuration for a 3D microstructuredbattery support. The structure was probed using XPS, SEM, BET, XRD and Raman techniques; revealingthat the foams were composed of a disordered carbon with a pore size in the <100 nm range resultingin a BET measured surface area of 433 m2 g-1. A reversible capacity exceeding 3.5 mA h cm2 at acurrent density of 0.37 mA cm-2 was achieved. SEM images of the foams after 50 cycles showed thatthe structure suffered no degradation. Furthermore, the foams were tested as a current collector bydepositing a layer of polyaniline cathode over their surface. High footprint area capacities of500 mA h cm-2 were seen in the voltage range 3.8 to 2.5 V vs. Li and a reasonable rate performancewas observed.

  • 12.
    Björklund, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hahlin, Maria
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    How the Negative Electrode Influences Interfacial and Electrochemical Properties of LiNi1/3Co1/3Mn1/3O2 Cathodes in Li-Ion Batteries2017In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 13, p. A3054-A3059Article in journal (Refereed)
    Abstract [en]

    The cycle life of LiNi1/3Co1/3Mn1/3O2 (NMC) based cells are significantly influenced by the choice of the negative electrode. Electrochemical testing and post mortem surface analysis are here used to investigate NMC electrodes cycled vs. either Li-metal, graphite or Li4Ti5O12 (LTO) as negative electrodes. While NMC-LTO and NMC-graphite cells show small capacity fading over 200 cycles, NMC-Li-metal cell suffers from rapid capacity fading accompanied with an increased voltage hysteresis despite the almost unlimited access of lithium. X-ray absorption near edge structure (XANES) results show that no structural degradation occurs on the positive electrode even after >200 cycles, however, X-ray photoelectron spectroscopy (XPS) results shows that the composition of the surface layer formed on the NMC cathode in the NMC-Li-metal cell is largely different from that of the other NMC cathodes (cycled in the NMC-graphite or NMC-LTO cells). Furthermore, it is shown that the surface layer thickness on NMC increases with the number of cycles, caused by continuous electrolyte degradation products formed at the Li-metal negative electrode and then transferred to NMC positive electrode.

  • 13.
    Björklund, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The influence of counter electrode on the capacity fading in LiNi0.33Mn0.33Co0.33O2-based Li-ion battery cells2017Conference paper (Other academic)
  • 14.
    Björklund, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Göttlinger, Mara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Investigation of dimethyl carbonate and propylene carbonate mixtures for LiNi0.6Mn0.2Co0.2O2-Li4Ti5O12 cells2019In: Chemelectrochem, E-ISSN 2196-0216, Vol. 6, no 13, p. 3429-3436Article in journal (Refereed)
    Abstract [en]

    It has recently been shown that ethylene carbonate (EC) experience poor stability at high potentials in lithium-ion batteries, and development of electrolytes without EC, not least using ethyl methyl carbonate (EMC), has therefore been suggested in order to improve the capacity retention. In this context, we here explore another alternative electrolyte system consisting of propylene carbonate (PC) and dimethyl carbonate (DMC) mixtures in NMC-LTO (LiNi0.6Mn0.2Co0.2O2, Li4Ti5O12) cells cycled up to 2.95 V. While PC experience wettability problems and DMC has difficulties dissolving LiPF6 salt, blends between these could possess complementary properties. The electrolyte blend showed superior cycling performance at sub-zero temperatures compared to EC-containing counterparts. At 30 degrees C, however, the PC-DMC electrolyte did not show any major improvement in electrochemical properties for the NMC-LTO cell chemistry. Photoelectron spectroscopy measurements showed that thin surface layers were detected on both NMC (622) and LTO electrodes in all investigated electrolytes. The results suggest that both PC and EC will react on the electrodes, but with EC forming thinner layers comprising more carbonates. Moreover, the electrochemical stability at high electrochemical potentials is similar for the studied electrolytes, which is surprising considering that most are free from the reactive EC component.

  • 15.
    Björklund, Erik
    et al.
    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.
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The influence of counter electrode on the capacity fading in LiNi0.33Mn0.33Co0.33O2-based Li-ion battery cells2017Conference paper (Other academic)
  • 16.
    Björklund, Erik
    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.
    Brant, William
    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.
    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.
    Temperature dependence of electrochemical degradation in LiNi1/3Mn1/3Co1/3O2/Li4Ti5O12 cells2019In: Energy Technology, ISSN 2194-4288, Vol. 7, no 9, article id 1900310Article in journal (Refereed)
    Abstract [en]

    Aging mechanisms in lithium‐ion batteries are dependent on the operational temperature, but the detailed mechanisms on what processes take place at what temperatures are still lacking. The electrochemical performance and capacity fading of the common cell chemistry LiNi1/3Mn1/3Co1/3O2 (NMC)/Li4Ti5O12 (LTO) pouch cells are studied at temperatures 10, 30, and 55 °C. The full cells are cycled with a moderate upper cutoff potential of 4.3 V versus Li+/Li. The electrode interfaces are characterized postmortem using photoelectron spectroscopy techniques (soft X‐ray photoelectron spectroscopy [SOXPES], hard X‐ray photoelectron spectroscopy [HAXPES], and X‐ray absorption near edge structure [XANES]). Stable cycling at 30 °C is explained by electrolyte reduction forming a stabilizing interphase, thereby preventing further degradation. This initial reaction, between LTO and the electrolyte, seems to be beneficial for the NMC–LTO full cell. At 55 °C, continuous electrolyte reduction and capacity fading are observed. It leads to the formation of a thicker surface layer of organic species on the LTO surface than at 30 °C, contributing to an increased voltage hysteresis. At 10 °C, large cell‐resistances are observed, caused by poor electrolyte conductivity in combination with a relatively thicker and LixPFy‐rich surface layer on LTO, which limit the capacity.

  • 17.
    Björklund, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wikner, Evelina
    Chalmers University of Technology, Gothenburg, Sweden.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Influence of state-of-charge in commercial LiNi0.33Mn0.33Co0.33O2/LiMn2O4-graphite cells analyzed by synchrotron-based photoelectron spectroscopy2018In: Journal of Energy Storage, ISSN 2352-152X, Vol. 15, p. 172-180Article in journal (Refereed)
    Abstract [en]

    Degradation mechanisms in 26 Ah commercial Li-ion battery cells comprising graphite as the negative electrode and mixed metal oxide of LiMn2O4 (LMO) and LiNi1/3Mn1/3Co1/3O2 (NMC) as the positive electrode are here investigated utilising extensive cycling at two different state-of-charge (SOC) ranges, 10–20% and 60–70%, as well as post-mortem analysis. To better analyze these mechanisms electrochemically, the cells were after long-term cycling reassembled into laboratory scale “half-cells” using lithium metal as the negative electrode, and thereafter cycled at different rates corresponding to 0.025 mA/cm2 and 0.754 mA/cm2. The electrodes were also analyzed by synchrotron-based hard x-ray photoelectron spectroscopy (HAXPES) using two different excitation energies to determine the chemical composition of the interfacial layers formed at different depth on the respective electrodes. It was found from the extensive cycling that the cycle life was shorter for the cell cycled in the higher SOC range, 60–70%, which is correlated to findings of an increased cell resistance and thickness of the SEI layer in the graphite electrode as well as manganese dissolution from the positive electrode.

  • 18.
    Björklund, Erik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wikner, Evelina
    Division of Electric Power Engineering, Chalmers University of Technology, Gothenburg, Sweden.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wachtler, 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.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The influence of temperature and SOC ranges of ageing in commercial  LiNi0.33Mn0.33Co0.33O2/LiMn2O4-graphite commercial cells2017Conference paper (Other academic)
  • 19.
    Brant, William
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mogensen, Ronnie
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Colbin, Simon
    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.
    Schmid, Siegbert
    Univ Sydney, Sch Chem, Sydney, NSW 2006, Australia.
    Häggstrom, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Ericsson, Tore
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Jaworski, Aleksander
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Pell, Andrew J.
    Stockholm Univ, Dept Mat & Environm Chem, SE-10691 Stockholm, Sweden.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Selective Control of Composition in Prussian White for Enhanced Material Properties2019In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 31, no 18, p. 7203-7211Article in journal (Refereed)
    Abstract [en]

    Sodium-ion batteries based on Prussian blue analogues (PBAs) are ideal for large-scale energy storage applications due to the ability to meet the huge volumes and low costs required. For Na2-xFe[Fe(CN)(6)](1-y)center dot zH(2)O, realizing its commercial potential means fine control of the concentration of sodium, Fe(CN)(6) vacancies, and water content. To date, there is a huge variation in the literature of composition leading to variable electrochemical performance. In this work, we break down the synthesis of PBAs into three steps for controlling the sodium, vacancy, and water content via an inexpensive, scalable synthesis method. We produce rhombohedral Prussian white Na1.88(5)Fe[Fe-(CN)(6)]center dot 0.18(9)H2O with an initial capacity of 158 mAh/g retaining 90% capacity after 50 cycles. Subsequent characterization revealed that the increased polarization on the 3 V plateau is coincident with a phase transition and reduced utilization of the high-spin Fe(III)/Fe(II) redox couple. This reveals a clear target for subsequent improvements of the material to boost long-term cycling stability. These results will be of great interest for the myriad of applications of PBAs, such as catalysis, magnetism, electrochromics, and gas sorption.

  • 20.
    Carboni, Marco
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Manzi, Jessica
    Univ Roma La Sapienza, Dipartimento Chim, Rome, Italy.
    Armstrong, Antony Robert
    Univ St Andrews, Sch Chem, EaStCHEM, St Andrews, Fife, Scotland.
    Billaud, Juliette
    Univ St Andrews, Sch Chem, EaStCHEM, St Andrews, Fife, Scotland.
    Brutti, Sergio
    Univ Roma La Sapienza, Dipartimento Chim, Rome, Italy.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Analysis of the Solid Electrolyte Interphase on Hard Carbon Electrodes in Sodium-Ion Batteries2019In: Chemelectrochem, ISSN 2196-0216, Vol. 6, no 6, p. 1745-1753Article in journal (Refereed)
    Abstract [en]

    The composition, morphology, and evolution of the solid electrolyte interphase (SEI) formed on hard carbon (HC) electrodes upon cycling in sodium‐ion batteries are investigated. A microporous HC was prepared by pyrolysis of d‐(+)‐glucose at 1000 °C followed by ball‐milling. HC electrodes were galvanostatically cycled at room temperature in sodium‐ion half‐cells using an aprotic electrolyte of 1 m sodium bis(trifluoromethanesulfonyl)imide dissolved in propylene carbonate with 3 wt % fluoroethylene carbonate additive. The evolution of the electrode/electrolyte interface was studied by impedance spectroscopy upon cycling and ex situ by spectroscopy and microscopy. The irreversible capacity displayed by the HC electrodes in the first galvanostatic cycle is probably due to the accumulation of redox inactive NaxC phases and the precipitation of a porous, organic‐inorganic hybrid SEI layer over the HC electrodes. This passivation film further evolves in morphology and composition upon cycling and stabilizes after approximately ten galvanostatic cycles at low current rates.

  • 21.
    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)
  • 22.
    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, ISSN 2046-2069, 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.

  • 23.
    Carboni, Marco
    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.
    Graphite Anode in K-ion Battery: The Solid Electrolyte Interphase probed by Photoelectron Spectroscopy2017Conference paper (Refereed)
  • 24.
    Christiansen, Ane S.
    et al.
    Technical University of Denmark.
    Stamate, Eugen
    Technical University of Denmark.
    Thydén, Karl
    Technical University of Denmark.
    Younesi, Reza
    Technical University of Denmark.
    Holtappels, Peter
    Technical University of Denmark.
    Plasma properties during magnetron sputtering of lithium phosphorous oxynitride thin films2015In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 273, p. 863-872Article in journal (Refereed)
    Abstract [en]

    The nitrogen dissociation and plasma parameters during radio frequency sputtering of lithium phosphorus oxynitride thin films in nitrogen gas are investigated by mass appearance spectrometry, electrostatic probes and optical emission spectroscopy, and the results are correlated with electrochemical properties and microstructure of the films. Low pressure and moderate power are associated with lower plasma density, higher electron temperature, higher plasma potential and larger diffusion length for sputtered particles. This combination of parameters favors the presence of more atomic nitrogen, a fact that correlates with a higher ionic conductivity. Despite of lower plasma density the film grows faster at lower pressure where the higher plasma potential, translated into higher energy for impinging ions on the substrate, resulted in a compact and smooth film structure. Higher pressures showed much less nitrogen dissociation and lower ion energy with thinner films, less ionic conductivity and poor film structure with large roughness.

  • 25. Das, Supti
    et al.
    Hojberg, Jonathan
    Knudsen, Kristian Basthohn
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Johansson, Patrik
    Norby, Poul
    Vegge, Tejs
    Instability of Ionic Liquid-Based Electrolytes in Li-O-2 Batteries2015In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 119, no 32, p. 18084-18090Article in journal (Refereed)
    Abstract [en]

    Ionic liquids (ILs) have been proposed as promising solvents for Li-air battery electrolytes. Here, several ILs have been investigated using differential electrochemical mass spectrometry (DEMS) to investigate the electrochemical stability in a Li-O-2 system, by means of quantitative determination of the rechargeability (GER/ORR), and thereby the Coulombic efficiency of discharge and charge. None of the IL-based electrolytes are found to behave as needed for a functional Li-O-2 battery but perform better than commonly used organic solvents. Also the extent of rechargeability/reversibility has been found to be strongly dependent on the choice of IL cation and anion as well as various impurities.

  • 26.
    Ebadi, Mahsa
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nasser, Antoine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory. ENSTA ParisTech, 828 Blvd Marechaux, F-91120 Palaiseau, France.
    Carboni, Marco
    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.
    Marchiori, Cleber
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Araujo, Carlos Moyses
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Theory.
    Insights into the Li-Metal/Organic Carbonate Interfacial Chemistry by Combined First-Principles Theory and X-ray Photoelectron Spectroscopy2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 1, p. 347-355Article in journal (Refereed)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) is a widely used technique to study surfaces and interfaces. In complex chemical systems, however, interpretation of the XPS results and peak assignments is not straightforward. This is not least true for Li-batteries, where XPS yet remains a standard technique for interface characterization. In this work, a combined density functional theory (DFT) and experimental XPS study is carried out to obtain the C 1s and O 1s core-level binding energies of organic carbonate molecules on the surface of Li metal. Decomposition of organic carbonates is frequently encountered in electrochemical cells employing this electrode, contributing to the build up of a complex solid electrolyte interphase (SEI). The goal in this current study is to identify the XPS fingerprints of the formed compounds, degradation pathways, and thereby the early formation stages of the SEI. The contribution of partial atomic charges on the core-ionized atoms and the electrostatic potential due to the surrounding atoms on the core-level binding energies, which is decisive for interpretation of the XPS spectra, are addressed based on the DFT calculations. The results display strong correlations between these two terms and the binding energies, whereas electrostatic potential is found to be the dominating factor. The organic carbonate molecules, decomposed at the surface of the Li metal, are considered based on two different decomposition pathways. The trends of calculated binding energies for products from ethereal carbon-ethereal oxygen bond cleavage in the organic carbonates are better supported when compared to the experimental XPS results.

  • 27.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sodium batteries and their interfaces2017Conference paper (Other academic)
  • 28.
    Edström, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    State of the art knowledge about interfaces and interphases in lithium and sodium batteries2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 256Article in journal (Other academic)
  • 29.
    Etman, Ahmed
    et al.
    Stockholm University.
    Inge, Ken
    Stockholm University.
    Jiaru, Xu
    Peking University.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Junliang
    Stockholm University, Peking University.
    A Water Based Synthesis of Ultrathin Hydrated Vanadium Pentoxide Nanosheets for Lithium Battery Application: Free Standing Electrodes or Conventionally Casted Electrodes?2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 252, p. 254-260Article in journal (Refereed)
    Abstract [en]

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

  • 30.
    Etman, Ahmed S.
    et al.
    Berzelii Center EXSELENT on Porous Materials, Department of Material and Environmental Chemistry (MMK), Stockholm University, Sweden.
    Inge, Andrew Kentaro
    Berzelii Center EXSELENT on Porous Materials, Department of Material and Environmental Chemistry (MMK), Stockholm University, Sweden.
    Jiaru, Xu
    College of Chemistry and Molecular Engineering, Peking University, China.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Junliang
    Berzelii Center EXSELENT on Porous Materials, Department of Material and Environmental Chemistry (MMK), Stockholm University, Sweden; College of Chemistry and Molecular Engineering, Peking University, China.
    Simple and Green Method for Fabricating V2O5·nH2O Nanosheets for Lithium Battery Application2017Conference paper (Other academic)
    Abstract [en]

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

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

    References:

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

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

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

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

  • 31.
    Imani, Roghayeh
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pazoki, Meysam
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Fernandes, Daniel L. A.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Mitev, Pavlin D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edvinsson, Tomas
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Tian, Haining
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Unravelling in-situ formation of highly active mixed metal oxide CuInO2 nanoparticles during CO2 electroreduction2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 49, p. 40-50Article in journal (Refereed)
    Abstract [en]

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

  • 32.
    Li, Cuiyan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Cai, Yanling
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhu, Yihua
    Ma, Mingguo
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Photocatalytic and antibacterial properties of Au-decorated Fe3O4@mTiO(2) core-shell microspheres2014In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 156, p. 314-322Article in journal (Refereed)
    Abstract [en]

    A facile approach for the fabrication of Au-decorated mesoporous Fe3O4@TiO2 (Fe3O4@mTiO(2)) core-shell microspheres is demonstrated. The protocol involved the coating of a successive layer of TiO2 onto a magnetic Fe3O4 core via a sol-gel process, followed by TiO2 crystallization and mesopore-formation by a hydrothermal treatment, and then the deposition of Au nanoparticles onto Fe3O4@mTiO(2) microspheres through an in situ reduction of perchloric acid. The mesoporous microspheres (Fe3O4@mTiO(2)) showed stronger magnetic properties than the dense sample (Fe3O4@TiO2) before the hydrothermal treatment. The size and loading amount of Au nanoparticles were controlled by the reduction temperature and concentration of Au salt, respectively. Compared to unmodified Fe3O4@mTiO(2) microspheres, Fe3O4@mTiO(2)@Au microspheres showed higher photocatalytic activity for organic degradation and antibacterial action in water. These core-shell Fe3O4@mTiO(2)@Au microspheres can serve as efficient and recyclable photocatalysts, which have promising applications in environmental treatment.

  • 33.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Rehnlund, David
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Karlsruhe Inst Technol, Dept Appl Biol, Inst Appl Biosci, Kaiserstr 12, D-76131 Karlsruhe, Germany.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Pettersson, Jean
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - BMC, Analytical Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Cambridge CB2 1EW, England.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    On the Capacity Losses Seen for Optimized Nano-Si Composite Electrodes in Li-Metal Half-Cells2019In: Advanced Energy Materials, ISSN 1614-6832, Vol. 9, no 33, article id 1901608Article in journal (Refereed)
    Abstract [en]

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

  • 34.
    Lindgren, Fredrik
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Niedzicki, Leszek
    Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Marcinek, Marek
    Warsaw Univ Technol, Fac Chem, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    SEI Formation and Interfacial Stability of a Si Electrode in a LiTDI-Salt Based Electrolyte with FEC and VC Additives for Li-Ion Batteries2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 24, p. 15758-15766Article in journal (Refereed)
    Abstract [en]

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

  • 35.
    Liu, Chenjuan
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Dong, Yanyan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Beijing Forestry Univ, Coll Mat Sci & Technol, Beijing Key Lab Lignocellulos Chem, Beijing 100083, Peoples R China..
    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..
    Towards an Understanding of Li2O2 Evolution in Li-O2 Batteries: An In-operando Synchrotron X-ray Diffraction Study2017In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 10, no 7, p. 1592-1599Article in journal (Refereed)
    Abstract [en]

    One of the major challenges in developing high-performance Li-O-2 batteries is to understand the Li2O2 formation and decomposition during battery cycling. In this study, this issue was investigated by synchrotron radiation powder X-ray diffraction. The evolution of Li2O2 morphology and structure was observed under actual electrochemical conditions of battery operation. By quantitatively tracking Li2O2 during discharge and charge, a two-step process was suggested for both growth and oxidation of Li2O2 owing to different mechanisms during two stages of both oxygen reduction reaction and oxygen evolution reaction. From an observation of the anisotropic broadening of Li2O2 in XRD patterns, it was inferred that disc-like Li2O2 grains are formed rapidly in the first step of discharge. These grains can stack together so that they facilitate the nucleation and growth of toroidal Li2O2 particles with a LiO2-like surface, which could cause parasitic reactions and hinder the formation of Li2O2. During the charge process, Li2O2 is firstly oxidized from the surface, followed by a delithiation process with a faster oxidation of the bulk by stripping the interlayer Li atoms to form an off-stoichiometric intermediate. This fundamental insight brings new information on the working mechanism of Li-O-2 batteries.

  • 36.
    Liu, Chenjuan
    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.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhu, Jie-Fang
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Insights into the Stability of Discharge Products in Na-O2 BatteriesManuscript (preprint) (Other academic)
  • 37.
    Liu, Chenjuan
    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.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Hedman, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    On the Stability of NaO2 in Na–O2 Batteries2018In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 10, no 16, p. 13534-13541Article in journal (Refereed)
    Abstract [en]

    Na–O2 batteries are regarded as promising candidates for energy storage. They have higher energy efficiency, rate capability, and chemical reversibility than Li–O2 batteries; in addition, sodium is cheaper and more abundant compared to lithium. However, inconsistent observations and instability of discharge products have inhibited the understanding of the working mechanism of this technology. In this work, we have investigated a number of factors that influence the stability of the discharge products. By means of in operando powder X-ray diffraction study, the influence of oxygen, sodium anode, salt, solvent, and carbon cathode were investigated. The Na metal anode and an ether-based solvent are the main factors that lead to the instability and decomposition of NaO2 in the cell environment. This fundamental insight brings new information on the working mechanism of Na–O2 batteries.

  • 38.
    Liu, Chenjuan
    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.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hedman, Jonas
    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.
    Gustafsson, Torbjörn
    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.
    Insights into the Stability of Discharge Products in Na-O2 Batteries2017Other (Other academic)
  • 39.
    Liu, Chenjuan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Qiu, Zhen
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Brant, William
    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, Technology, Department of Engineering Sciences, Applied Mechanics. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ma, Yue
    Northwestern Polytechnical University.
    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, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    A free standing Ru–TiC nanowire array/carbon textile cathode with enhanced stability for Li–O2 batteries2018In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 6, p. 23659-23668Article in journal (Refereed)
    Abstract [en]

    The instability of carbon cathode materials is one of the key problems that hinder the development of lithium–air/lithium–oxygen (Li–O2) batteries. In this contribution, a type of TiC-based cathode is developed as a suitable alternative to carbon based cathodes, and its stability with respect to its surface properties is investigated. Here, a free-standing TiC nanowire array cathode was in situ grown on a carbon textile, covering its exposed surface. The TiC nanowire array, via deposition with Ru nanoparticles, showed enhanced oxygen reduction/evolution activity and cyclability, compared to the one without Ru modification. The battery performance of the Li–O2cells with Ru–TiC was investigated by using in operando synchrotron radiation powder X-ray diffraction (SR-PXD) during a full cycle. With the aid of surface analysis, the role of the cathode substrate and surface modification is demonstrated. The presented results are a further step toward a wise design of stable cathodes for Li–O2 batteries.

  • 40.
    Liu, Chenjuan
    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.
    Brant, William R.
    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.
    Gustafsson, Torbjörn
    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.
    Growth of NaO2 in Highly Efficient Na–O2 Batteries Revealed by Synchrotron In Operando X-ray Diffraction2017In: ACS Energy Letters, E-ISSN 2380-8195, Vol. 2, p. 2440-2444Article in journal (Other academic)
    Abstract [en]

    The development of Na–O2 batteries requires understanding the formation of reaction products, as different groups reported compounds such as sodium peroxide, sodium superoxide, and hydrated sodium peroxide as the main discharge products. In this study, we used in operando synchrotron radiation powder X-ray diffraction (SR-PXD) to (i) quantitatively track the formation of NaO2 in Na–O2 cells and (ii) measure how the growth of crystalline NaO2 is influenced by the choice of electrolyte salt. The results reveal that the discharge could be divided into two time regions and that the formation of NaO2 during the major part of the discharge reaction is highly efficient. The findings indicate that the cell with NaOTf salt exhibited higher capacity than the cell with NaPF6 salt, whereas the average domain size of NaO2 particles decreases during the discharge. This fundamental insight brings new information on the working mechanism of Na–O2 batteries.

  • 41.
    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. 

  • 42.
    Liu, Jia
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Roberts, Matthew
    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.
    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.
    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.
    Accelerated Electrochemical Decomposition of Li2O2 under X-ray Illumination2013In: Journal of Physical Chemistry Letters, ISSN 1948-7185, E-ISSN 1948-7185, Vol. 4, no 23, p. 4045-4050Article in journal (Refereed)
    Abstract [en]

    This work presents the first report detailing the effect of X-rays on the electrochemical decomposition of Li2O2, which is the main reaction during the charging process in a Li-O-2 battery. An operando synchrotron radiation powder X-ray diffraction (SR-PXD) experiment was performed. The results indicate that the electrochemical decomposition of Li2O2 is dramatically accelerated under X-ray irradiation. The accelerated decomposition of Li2O2 follows a zero-order reaction, and the decomposition rate constant is proportional to the intensity of X-ray used. A mechanism for the electrochemical decomposition of Li2O2 under X-ray irradiation is proposed. These results give an insight into the charging process in Li-O-2 batteries.

  • 43.
    Liu, Jia
    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.
    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.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Pt/α-MnO2 nanotube: a highly active electrocatalyst for Li-Obattery2014In: Nano Energy, ISSN 2211-2855, Vol. 10, p. 19-27Article in journal (Refereed)
    Abstract [en]

    The preparation of α-MnO2 nanotubes (M-NT) decorated with platinum nanoparticles (Pt/M-NT) by a simple reduction and mechanical stirring method is presented in this work, which aims to design a highly active catalyst for the Li-O2 battery. The obtained samples were characterized by XRD, SEM, TEM, BET, and XPS techniques. The electrocatalytic performance of the prepared samples was evaluated by tracking the decomposition of Li2O2 during the charging process in a Li-O2 cell using in situ XRD and operando SR-PXD, which gave direct and time resolved information during the whole process. The results indicated that Pt nanoparticles were uniformly dispersed on the surface of M-NT. Even a small amount (1 wt%) of Pt on M-NT did largely enhance the kinetics of the charging process. A cell with 5 wt% Pt/M-NT showed the highest catalytic activity and lowest charging potential. The decomposition of Li2O2 during the charging process in a Li-O2 cell with 5 wt% Pt/M-NT followed a zero-order reaction. This promoting effect from the supported nanocatalyst can be attributed to the high surface area, highly dispersed and uniform Pt deposition, and proper surface state modifications.

  • 44.
    Ma, Le Anh
    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.
    Naylor, Andrew J.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Understanding charge compensation mechanisms in Na0.56Mg0.04Ni0.19Mn0.70O22019In: Communications chemistry, E-ISSN 2399-3669, Vol. 2, article id 125Article in journal (Refereed)
    Abstract [en]

    Sodium-ion batteries have become a potential alternative to Li-ion batteries due to the abundance of sodium resources. Sodium-ion cathode materials have been widely studied with particular focus on layered oxide lithium analogues. Generally, the capacity is limited by the redox processes of transition metals. Recently, however, the redox participation of oxygen gained a lot of research interest. Here the Mg-doped cathode material P2-Na0.56Mg0.04Ni0.19Mn0.70O2 is studied, which is shown to exhibit a good capacity (ca. 120 mAh/g) and high average operating voltage (ca. 3.5 V vs. Na+/Na). Due to the Mg-doping, the material exhibits a reversible phase transition above 4.3 V, which is attractive in terms of lifetime stability. In this study, we combine X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy techniques to shed light on both, cationic and anionic contributions towards charge compensation.

  • 45.
    Ma, Le Anh
    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.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Oxygen redox activity in Na0.67Ni0.25Mg0.05Mn0.7O22018In: Abstract for 5th international conference of sodium batteries 2018 in St. Malo, France (ICNaB 2018) 12th - 15th November 2018., 2018Conference paper (Other academic)
  • 46.
    Ma, Le Anh
    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.
    Solid Electrolyte Interphase (SEI) Formation in Sodium-Based Electrolytes2018In: Abstract for 5th international conference on sodium batteries in St. Malo, France (ICNaB 2018) 12th - 15th November 2018., 2018Conference paper (Other academic)
  • 47.
    Ma, Le Anh
    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.
    The solid electrolyte interphase formation in Na+-based electrolytes2017Conference paper (Other academic)
  • 48.
    Ma, Yue
    et al.
    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..
    Younesi, Reza
    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.
    Lee, Jim Yang
    Natl Univ Singapore, Dept Biomol & Chem Engn, Singapore 119260, Singapore..
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Iron Doping in Spinel NiMn2O4: Stabilization of the Mesoporous Cubic Phase and Kinetics Activation toward Highly Reversible Li+ Storage2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 22, p. 7698-7709Article in journal (Refereed)
    Abstract [en]

    Quaternary oxide structures with a three-dimensional macro/mesoporous network are synthesized via a facile nanocasting method followed by a calcination process. Structural engineering integrates multiscale pores by using a hydrophilic membrane with tunable-porosity as the sacrificial template. Through tailoring the metal precursor ratio, the tetragonal sites of spinel oxide are preferentially occupied by iron, resulting in a stabilized mesoporous cubic phase. Crystal field theory together with compositional characterizations from energy-dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), Mossbauer, and electron energy loss spectroscopy (EELS) direct our detailed analysis of the cation distribution in the spinel structures. Galvanostatic tests based on the best performing electrode exhibits a robust cycle life stable for 1200 cycles at a high current density of 1500 mA g(-1). This good Li+ storage performance could be attributed to the mutually beneficial synergy of the optimal level of iron doping which improves the electrical conductivity and structural robustness, as well as the presence of extended, hierarchical macro/mesoporous network. Finally, we demonstrate three feasible surface modification strategies for the oxide anodes toward better reversibility of Li+ storage.

  • 49.
    Massel, Felix
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Hikima, Kazuhiro
    Rensmo, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Suzuki, Kota
    Hirayama, Masaaki
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Liu, Yi-Sheng
    Guo, Jinghua
    Kanno, Ryoji
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Duda, Laurent
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Excess lithium in transition metal layers of epitaxially grown thin film cathodes of Li2MnO3 leads to rapid loss of covalency during first battery cycleIn: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455Article in journal (Other academic)
    Abstract [en]

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

  • 50.
    Mekonnen, Yedilfana S.
    et al.
    Technical University of Denmark.
    Knudsen, Kristian B.
    Technical University of Denmark.
    Mýrdal, Jon S. G.
    Technical University of Denmark.
    Younesi, Reza
    Technical University of Denmark.
    Højberg, Jonathan
    Technical University of Denmark.
    Hjelm, Johan
    Technical University of Denmark.
    Norby, Poul
    Technical University of Denmark.
    Vegge, Tejs
    Technical University of Denmark.
    Communication: The influence of CO2 poisoning on overvoltages and discharge capacity in non-aqueous Li-Air batteries2014In: The Journal of Chemical Physics, Vol. 140, no 12, p. 121101-1Article in journal (Refereed)
12 1 - 50 of 90
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