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  • 801.
    Vaughey, J.T.
    et al.
    Argonne National Laboratory US.
    Geyer, Andrea M.
    Fackler, Nathanael
    Johnson, Christopher S.
    Argonne National Laboratory US.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Bryngelsson, Hanna
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Benedek, Roy
    Thackeray, Michael M.
    Argonne National Laboratory.
    Studies of layered lithium metal oxide anodes in lithium cells2007In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 174, no 2, p. 1052-1056Article in journal (Refereed)
    Abstract [en]

    Numerous efforts have been made to use metal oxides as anode materials for lithium-ion batteries. In this study, we examined layered oxides of the type LiMO2 (M = Co, Ni) and Li2MO3 (M = Mn, Mo, Sn) in lithium cells and found them to be electrochemically active while possessing a high capacity. In general, LiMO2 electrodes provide higher reversible capacities than Li2MO3 electrodes. First-principles theoretical calculations were used as a guide to determine the most favorable reaction pathway from possible insertion (addition) reactions, decomposition reactions, and metal displacement reactions. For example, using in situ X-ray diffraction, LiCoO2 was found to discharge first to CoO and Li2O (decomposition reaction) and thereafter, upon further reduction, to Co metal and additional Li2O (displacement reaction). On charging to 3.0 V, only CoO was reformed; the electrode cycled with a reversible capacity of 575 mAh g−1; this reaction pathway is in good agreement with theoretical predictions.

  • 802.
    Wachtler, Mario
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    LIBchallenge: to challenge processes which limit life-time in Li-ion batteries2017Conference paper (Other academic)
    Abstract [en]

    LIBchallenge focusses on the development of high-energy density Li-ion batteries (HE-LIB) for potential automotive applications and on the investigation of dynamic effects and ageing phenomena depending on cell balance, material stability, electrode cross-talk and surface reactions. The HE-LIB will employ a graphite/silicon composite and Ni-rich layered nickel manganese cobalt oxides as high capacity anode and cathode, respectively.

  • 803. Wang, Hong-Yan
    et al.
    Liu, Jia
    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.
    Styring, Stenbjorn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Ott, Sascha
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Thapper, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    A Ru-Co hybrid material based on a molecular photosensitizer and a heterogeneous catalyst for light-driven water oxidation2014In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 16, no 8, p. 3661-3669Article in journal (Refereed)
    Abstract [en]

    A novel approach to anchor a molecular photosensitizer onto a heterogeneous water oxidation catalyst via coordination bonds is presented. A photosensitizer (1) based on [Ru(bpy)(3)](2+) and decorated with two methylenediphosphonate (M2P) groups has been designed and synthesized for this purpose. The M2P groups in complex 1 allow for coordination of cobalt ions to afford a novel molecular-heterogeneous hybrid material P1. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS) were used to characterize P1 as an amorphous, non-uniform material that contains Ru and Co in a ratio of 1:2. A suspension of P1 in a buffered aqueous solution is active as a light-driven water oxidation catalyst in the presence of persulfate (S2O82-) as electron acceptor. The yield of oxygen is higher when P1 is prepared in situ by mixing and illuminating 1 and Co2+ in the presence of S2O82-. After oxygen evolution ceases, a second material P2 can be isolated from the reaction mixture. P2 is characterized by a lower Ru content than P1, and contains Co in a higher oxidation state. Interestingly, P2 as a freshly prepared suspension is also active for light-driven water oxidation. It is shown that 1 resides in the interior of P1 and P2, and is thus in a location where undesirable quenching pathways of the photo-excited state of 1 limit the oxygen production yields for both P1 and P2.

  • 804.
    Wang, Huan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Emanuelsson, Rikard
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Liu, Haidong
    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.
    Mamedov, Fikret
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Molecular Biomimetics.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Sjödin, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Redox-State-Dependent Interplay between Pendant Group and Conducting Polymer Backbone in Quinone-Based Conducting Redox Polymers for Lithium Ion Batteries2019In: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 2, no 10, p. 7162-7170Article in journal (Refereed)
    Abstract [en]

    Conducting redox polymers (CRPs) have attracted increased interest in recent years because of the possibility of combining the favorable electron-transport properties of conducting polymers with the additional functionality provided by the redox active pendant groups (PGs). Herein we present a series of quinone-substituted PEDOT-CRPs where the quinone PGs have been substituted by electron-withdrawing substituents. Introducing electron-withdrawing substituents leads to an increase of the quinone formal potential, making, for example, CF3-substituted CRPs, a promising high-voltage cathode material for lithium ion batteries with a well-defined charge/discharge plateau around 3 V vs Li+/Li0. Interestingly, we find a shift in conductance onset potential concomitant with the quinone formal potential shift, indicating that the polymer backbone conductance is intimately associated with the PG redox chemistry. Through in situ UV–vis, electron paramagnetic resonance (EPR), and electrochemical quartz crystal microbalance experiments as well as by experiments in lithium- and tert-butyl-ammonium-based electrolytes, we show that the conductance delay is caused by the reduced lithiated quinone state, most likely by localizing the polaron charge carrier as indicated by EPR and UV–vis experiments.

  • 805.
    Wang, Shuai
    et al.
    Shanghai Univ.
    Shi, Liyi
    Shanghai Univ.
    Chen, Guorong
    Ba, Chaoqun
    Shanghai Univ.
    Wang, Zhuyi
    Shanghai Univ.
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhao, Yin
    Shanghai Univ.
    Zhang, Meihong
    Shanghai Univ.
    Yuan, Shuai
    Shanghai Univ.
    In Situ Synthesis of Tungsten-Doped SnO2 and Graphene Nanocomposites for High-Performance Anode Materials of Lithium-Ion Batteries2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 20, p. 17163-17171Article in journal (Refereed)
    Abstract [en]

    The composite of tungsten-doped SnO2 and reduced graphene oxide was synthesized through a simple one pot hydrothermal method. According to the structural characterization of the composite, tungsten ions were doped in the unit cells of tin dioxide rather than simply attaching to the surface. Tungsten-doped SnO2 was in situ grown on the surface of graphene sheet to form a three-dimensional conductive network that enhanced the electron transportation and lithium-ion diffusion effectively. The issues of SnO2 agglomeration and volume expansion could be also avoided because the, tungsten-doped SnO2 nanoparticles were homogeneously distributed on a graphene sheet. As a result, the nanocomposite electrodes of tungsten-doped SnO2 and reduced graphene oxide exhibited an excellent long-term cycling performance. The residual capacity was still as high as 1100 mA h g(-1) at 0.1 A g(-1) after 100 cycles. It still remained at 776 mA h g(-1) after 2000 cycles at the current density of lA g(-1).

  • 806.
    Wang, Yanan
    et al.
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Fu, Lixin
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Shi, Liyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Wang, Zhuyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhao, Yin
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Yuan, Shuai
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China;Shanghai Univ, Emerging Ind Inst, Jiaxing 314006, Zhejiang, Peoples R China.
    Gel Polymer Electrolyte with High Li+ Transference Number Enhancing the Cycling Stability of Lithium Anodes2019In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 11, no 5, p. 5168-5175Article in journal (Refereed)
    Abstract [en]

    Lithium anodes suffer from severe safety problems in liquid electrolyte systems that result from an unstable Li plating/stripping process and Li dendrite growth, leading to rapid degradation of Li metal batteries. A polyethylene (PE)-supported gel polymer electrolyte (GPE) with excellent electrolyte uptake/retention capability was simply prepared in this paper by the construction of cross-linked polymer networks (PNs) on the surface of a poly(ethylenimine)-primed PE separator to stabilize the lithium anode. The highly delocalized negative charge of p-styrene sulfonate groups on PNs plays a role in regulating the Li+ and anion transport, giving rise to a high Li+ transference number. This GPE extended the electrochemical stability to 4.8 V and improved the stability of interface between the electrolyte and lithium metal anode (reduced overpotential and suppressed lithium dendrites) during storage and repeated lithium plating/stripping cycling. The Li metal anode-based battery employing this GPE exhibits excellent cycling stability and C-rate capability.

  • 807.
    Wang, Yanan
    et al.
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Shi, Liyi
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Zhou, Hualan
    University of Shanghai for Science and Technology, School of Medical Instrument and Food Engineering, Shanghai.
    Wang, Zhuyi
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Li, Rui
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Qiu, Zhengfu
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Zhao, Yin
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Zhang, Meihong
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Yuan, Shuai
    Shanghai University, Research Center of Nanoscience and Nanotechnology, Shanghai.
    Polyethylene separators modified by ultrathin hybrid films enhancing lithium ion transport performance and Li-metal anode stability2018In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 259, p. 386-394Article in journal (Refereed)
    Abstract [en]

    Poor stability of lithium metal anodes in liquid electrolytes hinders its practical application in rechargeable batteries with very high energy density. Herein, we present an approach to tackle the intrinsic problems of Li metal anodes from the standpoint of separators. By a facile and versatile method based on mussel-inspired surface chemistry, a hybrid polydopamine/octaammonium POSS (PDA/POSS) coating was spontaneously formed on the surface of PE separators through the self-polymerization and strong adhesion feature of dopamine. This ultrathin PDA/POSS coating endows PE separators with different surface characteristics while keeping its microporous structure almost unchanged. The altered surface characteristics influence the separator/electrolyte interaction, and lead to remarkable enhanced ionic conductivity (from 0.36 mS cm−1 to 0.45 mS cm−1) and Li+ ion transference number (from 0.37 to 0.47) of PE separators as well as the improved stability of lithium/electrolyte interface, which effectively decreases the electrode polarization and suppresses the lithium dendrites formation, contributing to superior C-rates capability and cycling performance of cells.

  • 808.
    Wang, Yong-Lei
    et al.
    Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden;Stanford Univ, Dept Chem, Stanford, CA 94305 USA.
    Zhu, You-Liang
    Chinese Acad Sci, Changchun Inst Appl Chem, State Key Lab Polymer Phys & Chem, Changchun 130022, Jilin, Peoples R China.
    Lu, Zhong-Yuan
    Jilin Univ, Inst Theoret Chem, Lab Theoret & Computat Chem, State Key Lab Supramol Struct & Mat, Changchun 130021, Jilin, Peoples R China.
    Laaksonen, Aatto
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Stockholm Univ, Dept Mat & Environm Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden.
    Electrostatic interactions in soft particle systems: mesoscale simulations of ionic liquids2018In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 14, no 21, p. 4252-4267Article in journal (Refereed)
    Abstract [en]

    Computer simulations provide a unique insight into the microscopic details, molecular interactions and dynamic behavior responsible for many distinct physicochemical properties of ionic liquids. Due to the sluggish and heterogeneous dynamics and the long-ranged nanostructured nature of ionic liquids, coarse-grained mesa-scale simulations provide an indispensable complement to detailed first-principles calculations and atomistic simulations allowing studies over extended length and time scales with a modest computational cost. Here, we present extensive coarse-grained simulations on a series of ionic liquids of the 1-alkyl-3-methylimidazolium (alkyl = butyl, heptyl-, and decyl-) family with Cl, [BF4], and [PF6] counterions. Liquid densities, microstructures, translational diffusion coefficients, and re-orientational motion of these model ionic liquid systems have been systematically studied over a wide temperature range. The addition of neutral beads in cationic models leads to a transition of liquid morphologies from dispersed apolar beads in a polar framework to that characterized by bi-continuous sponge-like interpenetrating networks in liquid matrices. Translational diffusion coefficients of both cations and anions decrease upon lengthening of the neutral chains in the cationic models and by enlarging molecular sizes of the anionic groups. Similar features are observed in re-orientational motion and time scales of different cationic models within the studied temperature range. The comparison of the liquid properties of the ionic systems with their neutral counterparts indicates that the distinctive microstructures and dynamical quantities of the model ionic liquid systems are intrinsically related to Coulombic interactions. Finally, we compared the computational efficiencies of three linearly scaling O(NlogN) Ewald summation methods, the particle-particle particle-mesh method, the particle-mesh Ewald summation method, and the Ewald summation method based on a non-uniform fast Fourier transform technique, to calculate electrostatic interactions. Coarse-grained simulations were performed using the GALAMOST and the GROMACS packages and hardware efficiently utilizing graphics processing units on a set of extended [1-decyl-3-methylimidazolium][BF4] ionic liquid systems of up to 131072 ion pairs.

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  • 809.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Li, Mingkai
    Hubei Univ, Sch Mat Sci & Engn, Youyi Rd 368, Wuhan 430062, Hubei, Peoples R China.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials. Southwest Univ, Coll Food Sci, Chongqing 400715, Peoples R China.
    Liu, Chenjuan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhang, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting Polymer Paper-Derived Mesoporous 3D N-doped Carbon Current Collectors for Na and Li Metal Anodes: A Combined Experimental and Theoretical Study2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 41, p. 23352-23363Article in journal (Refereed)
    Abstract [en]

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

  • 810.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Redox-active Separators for High-capacity Lithium-ion Batteries2017In: Advanced SienceArticle in journal (Refereed)
    Abstract [en]

    High capacity lithium-ion batteries (LIBs) with good charge/discharge rate capabilities are profoundly needed to be able to meet next decade´s energy demand. Various new cathode materials and electrode engineering technologies that enhance battery performance have been developed, but less effort has been dedicated to improving capacity beyond optimizing the electrodes. We present an electrochemically active separator designed to enhance the capacity and charge/discharge rate capability of LIBs. The thin, mesoporous separator consists of an insulating nanocellulose layer in contact with an electrochemically active polypyrrole-nanocellulose supporting layer. Introducing polypyrrole into the separator i) minimizes the commonly observed “dead weight/volume”, ii) transforms the separator into a redox-active component with a conducting upper current-collecting layer, and iii) increases the pore size and porosity of the separator. In comparison with commercial batteries, our LIB with a LiFePO4 cathode and a redox-active separator shows an enhanced charge/discharge rate capability and a much greater capacity (320 mAh g-1) with respect to the weight of the cathode. Rendering the mesoporous separator redox-active could potentially also boost the capacity and rate performance of other types of lithium-ion batteries as well as electric energy storage devices in general. 

  • 811.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Redox-Active Separators for Lithium-Ion Batteries2018In: ADVANCED SCIENCE, ISSN 2198-3844, Vol. 5, no 3, article id 1700663Article in journal (Refereed)
    Abstract [en]

    A bilayered cellulose-based separator design is presented that can enhance the electrochemical performance of lithium-ion batteries (LIBs) via the inclusion of a porous redox-active layer. The proposed flexible redox-active separator consists of a mesoporous, insulating nanocellulose fiber layer that provides the necessary insulation between the electrodes and a porous, conductive, and redox-active polypyrrole-nanocellulose layer. The latter layer provides mechanical support to the nanocellulose layer and adds extra capacity to the LIBs. The redox-active separator is mechanically flexible, and no internal short circuits are observed during the operation of the LIBs, even when the redox-active layer is in direct contact with both electrodes in a symmetric lithium-lithium cell. By replacing a conventional polyethylene separator with a redox-active separator, the capacity of the proof-of-concept LIB battery containing a LiFePO4 cathode and a Li metal anode can be increased from 0.16 to 0.276 mA h due to the capacity contribution from the redox-active separator. As the presented redox-active separator concept can be used to increase the capacities of electrochemical energy storage systems, this approach may pave the way for new types of functional separators.

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  • 812.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sun, Rui
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Nanocellulose Structured Paper-Based Lithium Metal Batteries2018In: ACS Applied Energy Materials, ISSN 2574-0962, Vol. 1, no 8, p. 4341-4350Article in journal (Refereed)
    Abstract [en]

    We report for the first time, a lithium metal battery (LMB) design based on low-cost, renewable, and mechanically flexible nanocellulose fibers (NCFs) as the separator as well as substrate materials for both the positive and negative electrodes. Combined with carbon nanofibers, the NCFs yield 3D porous conducting cellulose paper (CCP) current collectors with large surface areas, enabling a low effective current density. The porous structure yields a dendrite-free deposition of lithium (Li), faciliates the mass transport within the electrodes, and also compensates for the volume changes during the cycling. Stable Li electrodes are obtained by electrodepositing Li on CCP substrates while positive electrodes are realized by embedding LiFePO4 (LFP) particles within the flexible CCP matrix. The mesoporous NCF separator features a homogeneous pore distribution which provides uniform current distributions at the electrodes. This effect, which yields a more homogeneous Li deposition on the negative electrode as well as improves the safety, lifespan, and sustainability of the LMB. As a result, the present all-nanocellulose-based LMB demonstrates excellent cycling stability for a Li metal battery obtained to date, with 91% capacity retention after 800 cycles and 85% capacity retention after 1000 cycles at a rate of 2 C (i.e., 1.27 mA cm–2).

  • 813.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pan, Ruijun
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ruan, Changqing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting polymer paper-derived separators for lithium metal batteries2018In: Energy Storage Materials, ISSN 2405-8297, Vol. 13, p. 283-292Article in journal (Refereed)
    Abstract [en]

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

  • 814.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Paper-Based Flexible Si anodes for Lithium-Ion Batteries 2015In: MRS Fall meeting 2015, Boston, 2015Conference paper (Refereed)
  • 815.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Huo, Jinxing
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Mechanics.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Flexible freestanding Cladophora nanocellulose paper based Si anodes for lithium-ion batteries2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 27, p. 14109-14115Article in journal (Refereed)
    Abstract [en]

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

  • 816.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Paper based flexible Si anodes for lithium ion batteries2016Conference paper (Other academic)
  • 817.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tammela, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Zhang, Peng
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strømme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Conducting Polymer Paper-Based Cathodes for High-Areal-Capacity Lithium–Organic Batteries2015In: Energy Technology, ISSN 2194-4296, Vol. 3, no 6, p. 563-569Article in journal (Refereed)
    Abstract [en]

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

  • 818.
    Wang, Zhaohui
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Zhang, Xiaoliang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Physical Chemistry.
    Zhou, Shengyang
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Strömme, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Nanotechnology and Functional Materials.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lightweight, Thin, and Flexible Silver Nanopaper Electrodes for High-Capacity Dendrite-Free Sodium Metal Anodes2018In: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028, Vol. 28, no 48, article id 1804038Article in journal (Refereed)
    Abstract [en]

    Owing to its resource-abundant and favorable theoretical capacity, sodium metal is regarded as a promising anode material for sodium metal batteries. However, uncontrolled Na plating/stripping, including Na dendrite growth during cycling, has hindered its practical application. Herein, a sodiophilic, thin, and flexible silver nanopaper (AgNP) is designed based on interpenetrated nanocellulose and silver nanowires and is used as a dendrite-free Na metal electrode. Due to a network of highly conducting silver nanowire (0.6 Ω sq?1, 8200 S cm?1), the sodiophilic nature of silver, and the reduced internal strain within the flexible AgNP, a compact Na metal layer can be uniformly deposited on and reversibly stripped from the AgNP electrode without any observations of Na dendrites during cycling at 1 mA cm?2 for 800 h. As the AgNP electrode is only 2 µm thick, with a low mass loading of 0.88 mg cm?2, the AgNP?Na anode deposited with a Na deposition charge of 6 mAh cm?2 exhibits a capacity of 995 mAh g?1AgNP?Na, approaching that of a Na metal anode (1166 mAh g?1Na). The present approach provides new possibilities for the development of lightweight and stable metal batteries.

  • 819. Wang, Zhuyi
    et al.
    Guo, Fangling
    Chen, Cheng
    Shi, Liyi
    Yuan, Shuai
    Sun, Lining
    Zhu, Jiefang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Self-Assembly of PEI/SiO2 on Polyethylene Separators for Li-Ion Batteries with Enhanced Rate Capability2015In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 7, no 5, p. 3314-3322Article in journal (Refereed)
    Abstract [en]

    A simple and environmentally friendly self-assembly process of oppositely charged polymer PEI and inorganic oxide SiO2 was demonstrated for the construction of an ultrathin layer on the surface of PE separator. The XPS, FT-IR, SEM, and EDS characterizations give clear evidence of the successful self-assembly of PEI and SiO2 without significantly increasing the thickness and sacrificing the pristine porous structure of PE separator. This process improves a variety of crucial properties of PE separator such as the electrolyte wetting, the electrolyte uptake, the thermal stability, the ionic conductivity, Li+ transference number, the electrochemical stability and the compatibility with lithium electrode, endowing lithium-ion battery (Li as anode and LiCoO2 as cathode) with excellent capacity retention at high C-rates and superior cycling performance. At the current density of 5 C, the cell with PE separator almost loses all the capacity. In contrast, the cell with (PEI/SiO2)-modified PE separator still holds 45.2% of the discharge capacity at 0.2 C. The stabilized SEI formation and high Li+ transference number of (PEI/SiO2)-modified PE separator were interpreted to be the substantial reasons leading to the remarkably enhanced battery performance, rendering some new insights into the role of the separator in lithium-ion batteries.

  • 820.
    Wei, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    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.
    Anodic TiO2 Nanotube Array Electrodes for High Energy Density and Power Density Li-ion and Na-ion Battery Applications2016Conference paper (Other academic)
  • 821.
    Wei, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    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.
    Free-Standing Oxide Nanotube Array Electrodes for High Energy Density and Power Density Li-Ion Batteries2016Conference paper (Other academic)
  • 822.
    Wei, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala Univ, Dept Chem, Angstrom Lab, Angstrom Adv Battery Ctr, SE-75121 Uppsala, Sweden..
    Hybrid Energy Storage Devices Based on Monolithic Electrodes Containing Well-defined TiO2 Nanotube Size Gradients2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 176, p. 1393-1402Article in journal (Refereed)
    Abstract [en]

    Well-defined TiO2 nanotube size gradient thin films, manufactured using a bipolar electrochemistry approach, can be used as versatile monolithic hybrid electrodes for energy storage devices. The nanotube size distribution within the gradients can readily be controlled by altering the bipolar current and/or the length of the bipolar titanium sheet. As the electrochemical properties of the gradient electrodes can be carefully tailored by modifying the nanotube size gradient, this approach provides new possibilities for the manufacturing of hybrid electrodes with integrated energy and power density gradients. The freestanding anatase TiO2 nanotube size gradient electrodes provide unprecedented capacities at cycling rates from C/5 (i.e. 162 mAh cm(-2) or 169 mAh g(-1)) to 50C (i.e. 40 mAh cm(-2) or 42 mAh g(-1)). It is likewise shown that the size gradient electrodes facilitate fundamental studies of the charge/discharge process of TiO2 based electrodes. The results demonstrate that the different shapes of charge and discharge curves of TiO2 nanotube electrode can be explained by inherent differences between the lithiation and delithiation processes.

  • 823.
    Wei, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ihrfors, Charlotte
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    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.
    Binder-free oxide nanotube array electrodes for high energy density and power density Li-ion batteries2015Conference paper (Other academic)
    Abstract [en]

    Over the past few years, with the increasing power demanding for critical applications from portable devices to electric vehicles, more and more emphasis are focused on achieving high energy and power density Li-ion batteries, i.e., to maximize energy density while retaining a high rate capability. So far, the studies have been mainly dedicated to the development of powder type electrode materials and relatively little attention has been paid to studies of other electrode architectures. Composite electrodes containing a mixture of the active material in the form of a powder (60 wt. %-80 wt. %), binders and conductive additives are still commonly used, which however yield poor material utilization, porous electrode arrangements (i.e. porosities of ~50%) and a lot of complex interfaces.

      In the present work, we demonstrate that highly ordered, binder-free anodic oxide nanotube array electrodes can be used for high energy density and power density Li-ion battery applications. By using 9 mm long anatase TiO2 nanotube electrodes, an areal capacity of 0.19 mAh cm-2 (i.e., 76 mAh g-1) at a charge /discharge current density of 3.5 mA cm-2 (10C rate), and 0.37 mAh cm-2 (i.e., 150 mAh g-1) at 0.07 mA cm-2, can be achieved.[1]  The influence of the nanotube geometry, e.g., length and diameter, on the battery performance was investigated. It is also demonstrated that the rate capability of the nanotube electrode depends mainly on the rate of the electron transfer associated with the lithiation /delithiation reaction with the nanotube length up to 14 mm. With further increased nanotube length, the rate capability of nanotube electrode gradually decays but the areal capacity of nanotube electrodes can still be increased up to 1 mAh cm-2 with the tube length of 40 mm. [2] On the other side, well-defined TiO2 nanotube size gradient thin films can be manufactured using a bipolar electrochemistry approach, which contains well controlled nanotube size distribution and can be readily be used as versatile monolithic hybrid electrodes for energy storage devices.[3] Such free-standing anatase TiO2 nanotube size gradient electrodes provide unprecedented areal capacities at cycling rates from C/5 (i.e. 175 mAh cm-2) to 50C (i.e. 40 mAh cm-2).

     

    References

    1. W. Wei, G. Oltean, C. -W. Tai, K. Edström, F. Björefors, L. Nyholm, J. Mater. Chem. A 2013, 1,8160
    2. W. Wei, C. Ihrfors, F. Björefors, L. Nyholm, J. Mater. Chem. A,  in manuscript
    3. W. Wei, F. Björefors, L. Nyholm, J. Mater. Chem. A,  under review

     

  • 824.
    Wei, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Oltean, Gabriel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Tai, Cheuk-Wai
    Stockholm University.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    High energy and power density TiO2 nanotube electrodes for 3D Li-ion microbatteries2013In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 1, no 28, p. 8160-8169Article in journal (Refereed)
    Abstract [en]

    Highly ordered anodic TiO2 nanotube arrays with a tube length of 9 [small mu ]m are shown to provide areal capacities of 0.24 mA h cm-2 (i.e. 96 mA h g-1) at a charge/discharge current density of 2.5 mA cm-2 (corresponding to a rate of 5 C) and 0.46 mA h cm-2 (i.e. 184 mA h g-1) at 0.05 mA cm-2, when used as 3D free-standing anodes in Li-ion microbatteries. The present nanotube electrodes, which could be cycled for 500 cycles with only 6% loss of capacity, exhibited significantly higher energy and power densities, as well as an excellent cycling stability compared to previously reported TiO2-based Li-ion microbattery electrodes. The influence of parameters such as ordering, geometry and crystallinity of the nanotubes on the microbattery performance was investigated. A two-step anodization process followed by annealing of the nanotubes was found to yield the best microbattery performance. It is also demonstrated that the rate capability of the electrode depends mainly on the rate of the structural rearrangements associated with the lithiation/delithiation reaction and that the areal capacity at various charge/discharge rates can be increased by increasing the tube wall thickness or the length of the nanotubes, up to 0.6 mA h cm-2 for 100 cycles.

  • 825.
    Wei, Wei
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Valvo, Mario
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Nyholm, Leif
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Size-dependent Electrochemical Performance of Monolithic Anatase TiO2 Nanotube Anodes for Sodium-ion Batteries2018In: ChemElectroChem, Vol. 5, no 4, p. 674-684Article in journal (Refereed)
    Abstract [en]

    Well-defined, monolithic TiO2 nanotube thin films havebeen used as model anode electrodes to study Na-ion storage in anatase TiO2. It is shown that anatase TiO2 nanotubes with wall thicknesses up to 50 nm can be transformed into amorphous sodium titanate (e.g. Na0.2TiO2) nanotubes via an electrochemical activation process at about 0.2 V vs. Na+/Na. Due to the Na+ insertion and extraction reactions at about 0.55 and 0.75 V vs. Na+/Na, respectively, the activated TiO2 nanotubes exhibit reversible capacities of 170 mAh g-1. For the first time, it is shown that the nanotube length and wall thickness play critical roles in determining the electrochemical performances of this type of electrodes in Na-ion cells. An excellent rate performance, yielding capacities of about 33mAh g-1 at 20C and 161 mAh g-1 at C/5 rates, as well as a capacity retention of more than 97% after more than 350 cycles, could be achieved with nanotubes with a wall thickness of up to 20 nm. Thecycling rate for the nanotubes with a tube length of 4.5 μm should,however, be limited to 1C to guarantee a cycle life of about 200 cycles.

  • 826.
    Wen, Rui-Tao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics. MIT, Ctr Mat Proc, Cambridge, MA 02139 USA..
    Malmgren, Sara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Granqvist, Claes G.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Niklasson, Gunnar A.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Degradation Dynamics for Electrochromic WO3 Films under Extended Charge Insertion and Extraction: Unveiling Physicochemical Mechanisms2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 14, p. 12872-12877Article in journal (Refereed)
    Abstract [en]

    Degradation of electrochromic thin films under extended charge insertion and extraction is a technically important phenomenon for which no in-depth understanding is currently on hand. Here, we report on an explorative study of sputter-deposited WO3 films in a Li-ion-conducting electrolyte by use of cyclic voltammetry, in situ optical transmittance, and impedance spectroscopy. A cycling-dependent decrease of the charge capacity could be accurately modeled by a power-law function, and impedance spectroscopy gave evidence for anomalous diffusion as well as a higher charge transfer resistance during deintercalation than during intercalation. Thus, a consistent conceptual picture emerged for the degradation dynamics; it includes the growth of an interfacial barrier layer and also embraces anomalous diffusion coupled with dispersive power-law chemical kinetics.

    Download full text (pdf)
    fulltext
  • 827.
    Whittle, Thomas A.
    et al.
    Univ Sydney, Sch Chem, Sydney, NSW 2006, Australia..
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Sydney, Sch Chem, Sydney, NSW 2006, Australia..
    Hester, James R.
    Australian Nucl Sci & Technol Org, Kirrawee DC, NSW 2253, Australia..
    Gu, Qinfen
    Australian Synchrotron, 800 Blackburn Rd, Clayton, Vic 3168, Australia..
    Schmid, Siegbert
    Univ Sydney, Sch Chem, Sydney, NSW 2006, Australia..
    Tailoring phase transition temperatures in perovskites via A-site vacancy generation2017In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 46, no 22, p. 7253-7260Article in journal (Refereed)
    Abstract [en]

    The structures across the Sr0.8Ti0.6-xZrxNb0.4O3, 0 <= x <= 0.6, defect perovskite series were investigated using complementary synchrotron X-ray and neutron powder diffraction data. The locations of second order compositional and temperature dependent phase transitions between the high symmetry cubic Pm (3) over barm phase and the lower symmetry tetragonal I4/mcm phase were determined. Deviation of the oxygen x coordinate from the high symmetry value and the B-O-B bond angle from 180 degrees as well as the tetragonal strain squared were each found to be suitable order parameters to monitor the transitions. Tolerance factor calculations confirmed that these A-site deficient perovskites retain a higher symmetry to a lower value than their fully occupied counterparts. Therefore, adjusting vacancy concentrations can be employed as a general strategy to design compounds with specifically tailored phase transition temperatures.

    Download full text (pdf)
    fulltext
  • 828. Whittle, Thomas A.
    et al.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Withers, Ray L.
    Liu, Yun
    Howard, Christopher J.
    Schmid, Siegbert
    Novel insight into the structure and properties of lead-free dielectric Sr3TiNb4O152018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 33, p. 8890-8896Article in journal (Refereed)
    Abstract [en]

    Sr3TiNb4O15 has been synthesised and its structure and dielectric properties characterised. In contrast to previously reported results the compound has been found to form with Pna21 symmetry and unit cell dimensions a = 12.3631(19), b = 12.4027(19) and c = 7.7601(12) Å. Variable temperature studies show a phase transition from orthorhombic to tetragonal symmetry at approximately 625 K, much higher than previously reported. Temperature-dependent dielectric measurements have also been performed and these correlate very well with the observed phase transition temperature.

  • 829.
    Wieczorek, P.
    et al.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Bitner-Michalska, A.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Niedzicki, L.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Zero, E.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Zukowska, G. Z.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wieczorek, W.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Marcinek, M.
    Warsaw Univ Technol, Fac Chem, Polymer Ion Res Grp, Noakowskiego 3, PL-00664 Warsaw, Poland..
    Compatibility of microwave plasma chemical vapor deposition manufactured Si/C electrodes with new LiTDI-based electrolytes2016In: Solid State Ionics, ISSN 0167-2738, E-ISSN 1872-7689, Vol. 286, p. 90-95Article in journal (Refereed)
    Abstract [en]

    A synthesis of new types of Si/C composite anodes for lithium -ion batteries is reported. Thin layers of graphitic carbon decorated in 3D with Si nanoparticles were produced from liquid organic precursors-1-phenyl-2trimethylsilylacetylene and triethoxy(octyl)silane, using a one-step microwave plasma chemical vapor deposition (MPCVD) method. Thin-film Si/C electrodes were electrochemically tested in lithium half cells and produced a good reversible capacity of up to 900 mAh g-1 (after 100 cycles) and -370 mAh g(-1), depending on the precursor type. The electrode easily endured 100 cycles at 1C rate with only a 10% loss in capacity.

  • 830.
    Wijaya, Olivia
    et al.
    TUM CREATE, Singapore 138602, Singapore..
    Hartmann, Pascal
    Univ Giessen, Inst Phys Chem, D-35392 Giessen, Germany..
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Markovits, Iulius I. E.
    Nanyang Technol Univ, Energy Res Inst, Singapore 637141, Singapore..
    Rinaldi, Ali
    TUM CREATE, Singapore 138602, Singapore..
    Janek, Jurgen
    Univ Giessen, Inst Phys Chem, D-35392 Giessen, Germany..
    Yazami, Rachid
    Nanyang Technol Univ, Energy Res Inst, Singapore 637141, Singapore..
    A gamma fluorinated ether as an additive for enhanced oxygen activity in Li-O-2 batteries2015In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 3, no 37, p. 19061-19067Article in journal (Refereed)
    Abstract [en]

    Perfluorocarbons (PFCs) are known for their high O-2 solubility and have been investigated as additives in Li-O-2 cells to enhance the cathode performance. However, the immiscibility of PFCs with organic solvents remains the main issue to be addressed as it hinders PFC practical application in Li-O-2 cells. Furthermore, the effect of PFC additives on the O-2 mass transport properties in the catholyte and their stability has not been thoroughly investigated. In this study, we investigated the properties of 1,1,1,2,2,3,3,4,4-nonafluoro-6-propoxyhexane (TE4), a gamma fluorinated ether, and found it to be miscible with tetraglyme (TEGDME), a solvent commonly used in Li-O-2 cells. The results show that with the TE4 additive up to 4 times higher O-2 solubility and up to 2 times higher O-2 diffusibility can be achieved. With 20 vol% TE4 addition, the discharge capacity increased about 10 times at a high discharge rate of 400 mA g(C)(-1), corresponding to about 0.4 mA cm(-2). The chemical stability of TE4 after Li-O-2 cell discharge is investigated using H-1 and F-19 NMR, and the TE4 signal is retained after discharge. FTIR and XPS measurements indicate the presence of Li2O2 as a discharged product, together with side products from the parasitic reactions of LiTFSI salt and TEGDME.

  • 831.
    Wijaya, Olivia
    et al.
    TUM CREATE, Singapore 138602, Singapore.; Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore.
    Rinaldi, Ali
    TUM CREATE, Singapore 138602, Singapore.; King Fahd Univ Petr & Minerals, Dept Chem, Dhahran 31261, Saudi Arabia.
    Younesi, Reza
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Yazami, Rachid
    TUM CREATE, Singapore 138602, Singapore.; Nanyang Technol Univ, Sch Mat Sci & Engn, Singapore 639798, Singapore.; Nanyang Technol Univ, Energy Res Inst, Singapore 637141, Singapore.
    The Origin of Li-O2 Battery Performance Enhancement Using Fluorocarbon Additive2016In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 163, no 13, p. A2660-A2664Article in journal (Refereed)
    Abstract [en]

    Perfluorocarbon compounds (PFC) are known for their high O2 dissolution capability and have been investigated as additives/electrolyte solvents to improve Li-O2 batteries performance. Nevertheless, systematic studies that go beyond the proof of concept that fluorocarbon additives enhance the performance of Li-O2 batteries have not been carried out yet. In this work, we investigate 1-methoxyheptafluoropropane additive (1-PFC), a fluorocarbon with an ether functional group that has been considered as one of the candidates as additives in the Li-O2 battery. Using electrochemical methods and physical characterization of discharge products, we found that the enhancement of the discharge capacity of Li-O2 cells with 1-PFC additive is most likely correlated with instability of the 1-PFC additive against superoxide radicals, rather than the improvement in O2 solubility.

  • 832.
    Wikberg, J. Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Dahbi, M.
    ECME, LP2E2M, FST Marrakech, University Cadi Ayyad.
    Saadoune, I.
    ECME, LP2E2M, FST Marrakech, University Cadi Ayyad.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Dimensionality crossover and frustrated spin dynamics on a triangular lattice2010In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 81, no 22, p. 224411-Article in journal (Refereed)
    Abstract [en]

    Investigations of the magnetic behavior of the layered oxide, LiNi0.65Co0.25Mn0.10O2, through ac and time-dependent susceptibility, dc linear and nonlinear susceptibility as well as neutron-diffraction measurements are presented. A ferrimagneticlike spin ordering appears at 119 K with a spontaneous magnetization coexisting with spin frustration in two dimensions (2D). At lower temperature, a cluster-glass transition is found at 17.4 K indicating a transformation to a completely frustrated state in three dimensions (3D). A dimensionality crossover with temperature, from 2D to 3D, in a magnetically frustrated system has been demonstrated. The observed magnetic behavior is believed to originate from a percolating system of spin clusters defined by disordered and frustrated exchange interactions and the findings conform well with predictions of the percolation cluster model.

  • 833.
    Wikberg, J. Magnus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Dahbi, Mohammed
    ECME, LP2E2M, FST Marrakech, University Cadi Ayyad.
    Saadoune, Ismael
    ECME, LP2E2M, FST Marrakech, University Cadi Ayyad.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Materials Chemistry, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Svedlindh, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
    Magnetic order, aging, and spin frustration in a percolating spin system, LiNi0.8Co0.1Mn0.1O22010In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 8, p. 083909-Article in journal (Refereed)
    Abstract [en]

    Structural and magnetic properties of the Li layered oxide, LiNi0.8Co0.1Mn0.1O2, have been studied by means of x-ray diffraction, dc magnetization, ac linear, and nonlinear susceptibility as well as by magnetic aging and temperature cycling experiments. A percolating spin system interacting via antiferromagnetic and ferromagnetic superexchange interactions of different strength induce a ferrimagnetic quasilong-range order with a transition temperature Tc ≈ 70 K, a Weiss temperature of −25 K and an effective magnetic moment of 2.07 μB. On cooling below Tc the two-dimensional (2D) triangular lattice built up of edge-sharing metal oxide octahedras first exhibits a 2D spin glass like behavior followed by complete spin frustration in three dimensions below 30 K. The findings correlate well with expectations for a ferrimagnetic reentrant cluster glass system as well as with predictions of the percolating cluster model.

  • 834.
    Wolf, Matthew
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Alexander, Shluger
    Department of Physics and Astronomy, University College London.
    The Structure and Properties of Clean Steps at Oxide Surfaces2015In: Defects at Oxide Surfaces, Springer Publishing Company, 2015, 58, p. 191-214Chapter in book (Refereed)
  • 835.
    Wolf, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Castleton, Christopher W. M.
    Nottingham Trent Univ, Sch Sci & Technol, Nottingham, England;Malardalen Univ, Div Phys & Math Nat Sci Didact, Vasteras, Sweden.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    STM Images of Anionic Defects at CeO2(111)-A Theoretical Perspective2019In: Frontiers in Chemistry, E-ISSN 2296-2646, Vol. 7, article id 212Article in journal (Refereed)
    Abstract [en]

    We present a theoretically oriented analysis of the appearance and properties of plausible candidates for the anionic defects observed in scanning tunneling microscopy (STM) experiments on CeO2(111). The simulations are based on density functional theory (DFT) and cover oxygen vacancies, fluorine impurities and hydroxyl groups in the surface and sub-surface layers. In the surface layer, all three appear as missing spots in the oxygen sublattice in filled state simulated STM images, but they are distinguishable in empty state images, where surface oxygen vacancies and hydroxyls appear as, respectively, diffuse and sharp bright features at oxygen sites, while fluorine defects appear as triangles of darkened Ce ions. In the sub-surface layer, all three defects present more complex patterns, with different combinations of brightened oxygen ion triangles and/or darkened Ce ion triangles, so we provide image maps to support experimental identification. We also discuss other properties that could be used to distinguish the defects, namely their diffusion rates and distributions.

    Download full text (pdf)
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  • 836.
    Wolf, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mitev, Pavlin D.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Briels, Wim
    Computational Biophysics, University of Twente, The Netherlands 3.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fluorine clusters at CeO2(111) - A DFT+U and Monte Carlostudy2017Conference paper (Other academic)
    Abstract [en]

    STM experiments on CeO2(111) reveal depressions in the surface oxygen sub-lattice which are observed to form clusters of various shapes and sizes [1].While these depressions were assumed to be oxygen vacancies, subsequent DFTcalculations have indicated that clusters of oxygen vacancies are energeticallyunstable [2-4]. Recently, we showed theoretically that fluorine impurities shouldappear almost identical to oxygen vacancies in STM experiments, but that theirproperties are more in line with those of the defects observed in experiments [5].Here, I will present the results of a further investigation into the distribution ofF impurity clusters at CeO2(111), using a combination of DFT+U calculations,and Monte Carlo sampling based on a simple but accurate pair potential whichwas fitted to the DFT results. The distribution is characterised in terms of thenumber of clusters of a certain size, and also on their topology, i.e. whetherthey are compact or open/linea r. Our results compare favourably with theexperiments, and also exhibit some interesting physics in their own right.

    [1] F. Esch et al., Science 309, 752 (2005).[2] J. Conesa, Cat. Today 143, 315 (2009).[3] C. Zhang et al., Phys. Rev. B 79, 075433 (2009).[4] X.-P. Wu & X.-Q. Gong, Phys. Rev. Lett. 116, 086102 (2016).[5] J. Kullgren, M. J. Wolf et al., Phys. Rev. Lett. 112, 156102 (2014).

  • 837.
    Wolf, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Broqvist, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Fluorine impurities at CeO2(111): Effects on oxygen vacancy formation, molecular adsorption, and surface re-oxidation2017In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 146, no 4, article id 044703Article in journal (Refereed)
    Abstract [en]

    We investigate the effects of anion doping with fluorine impurities on the chemistry of the CeO2 (111) facet, using the results of DFT+U calculations. We consider three prototypical processes: the formation of oxygen vacancies, the adsorption of O-2 and H2O molecules, and the re-oxidation of the surface with fragments of the two molecules. We find that the first two of these processes are not strongly affected, but that the presence of F lowers the energy gained in the re-oxidation of the surface in comparison to the healing of an oxygen vacancy, by 1.47 eV in the case of O-2 (provided that the F is part of a cluster) and by 0.92 eV in the case of H2O. Based on these results, we suggest that F could enhance the redox chemistry of ceria by toggling between being in the surface and on the surface, effectively facilitating the release of lattice O by acting as a "place holder" for it. Finally, we find that the desorption of F as either 1/2 F-2 or HF is energetically unfavourable, suggesting that F doped ceria should be stable in the presence of O-2 and H2O.

  • 838.
    Wolf, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Broqvist, Peter
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Interaction of Oxygen and Water Molecules with Flourine Impurities at CeO2(111) surface2016In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690Article in journal (Refereed)
  • 839.
    Wolf, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Comment on: "Clustering of Oxygen Vacancies at CeO2(111): Critical Role of Hydroxyls"2016In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 117, no 27, article id 279601Article in journal (Refereed)
  • 840.
    Wolf, Matthew J.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Kullgren, Jolla
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hermansson, Kersti
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Comment on "Clustering og Oxygen Vacancies at CeO2(111): Crytical Role of Hydroxyls"2016In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114Article in journal (Refereed)
  • 841.
    Wu, Yuan
    et al.
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Chen, Guorong
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Wang, Zhuyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Zhao, Yin
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Shi, Liyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhang, Meihong
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Jia, Rongrong
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Yuan, Shuai
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    In situ constructed Ag/C conductive network enhancing the C-rate performance of Si based anode2018In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 17, p. 102-108Article in journal (Refereed)
    Abstract [en]

    Poor intrinsic electrical conductivity as well as considerable volume change during lithium alloying/dealloying process has been a critical defect for high theoretical capacity silicon-based anodes. In our work, we demonstrate the synthesis design of multiscale recombined dendritic Si/Ag/C anode for high energy density LIBs via compositing bulky silicon with uniformly distributed Ag NPs, followed by a carbon source PDA (polydopamine) coating step. Here Ag NPs are generated by an in situ redox reaction between Ag+ and PDA, no need for additional reducing agents. According to the characterization analysis, the robust porous Si/Ag/C structure can provide channels for fast Li+ diffusion and electron conduction, promoting the formation of a thinner and more stable SEI film. As a result, the Si/Ag/C composite anode still yields a relatively high residual capacity of 1422.1 mAh g (1) after 100 cycles at 0.2 A g (1). In addition, it remains 633.1 mAh g (1) after 500 cycles at a high current density of 8 A g (1).

  • 842.
    Xia, Chen
    et al.
    Royal Inst Technol KTH, Dept Energy Technol, SE-10044 Stockholm, Sweden;Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430062, Peoples R China.
    Cai, Yixiao
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences. Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430062, Peoples R China.
    Ma, Yue
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wang, Baoyuan
    Royal Inst Technol KTH, Dept Energy Technol, SE-10044 Stockholm, Sweden;Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430062, Peoples R China.
    Zhang, Wei
    Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430062, Peoples R China.
    Karlsson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
    Wu, Yan
    China Univ Geosci, Fac Mat Sci & Chem, Wuhan 430074, Peoples R China.
    Zhu, Bin
    Royal Inst Technol KTH, Dept Energy Technol, SE-10044 Stockholm, Sweden;Hubei Univ, Fac Phys & Elect Technol, Hubei Collaborat Innovat Ctr Adv Mat, Wuhan 430062, Peoples R China.
    Natural Mineral-Based Solid Oxide Fuel Cell with Heterogeneous Nanocomposite Derived from Hematite and Rare-Earth Minerals2016In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 32, p. 20748-20755Article in journal (Refereed)
    Abstract [en]

    Solid oxide fuel cells (SOFCs) have attracted much attention worldwide because of their potential for providing clean and reliable electric power. However, their commercialization is subject to the high operating temperatures and costs. To make SOFCs more competitive, here we report a novel and attractive nanocomposite hematite LaCePrOx (hematite LCP) synthesized from low-cost natural hematite and LaCePr-carbonate mineral as an electrolyte candidate. This heterogeneous composite exhibits a conductivity as high as 0.116 S cm(-1) at 600 degrees C with an activation energy of 0.50 eV at 400-600 degrees C. For the first time, a fuel cell using such a natural mineral-based composite demonstrates a maximum power density of 625 mW cm(-2) at 600 degrees C and notable power output of 386 mW cm(-2) at 450 degrees C. The extraordinary ionic conductivity and device performances are primarily attributed to the heterophasic interfacial conduction effect of the hematite-LCP composite. These superior properties, along with the merits of ultralow cost, abundant storage, and eco-friendliness, make the new composite a highly promising material for commercial SOFCs.

  • 843.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    All silicon lithium-ion batteries2015Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:uu:diva-253257 (URN)10.1021/acs.chemmater.5b00339 (DOI)000353176100041 ()
    Funder
    StandUp
    Available from: 2015-05-26 Created: 2015-05-25 Last updated: 2020-02-17Bibliographically approved
    2. A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
    Open this publication in new window or tab >>A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
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    2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 301, p. 105-112Article in journal (Refereed) Published
    Abstract [en]

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

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

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

    National Category
    Chemical Sciences Engineering and Technology
    Identifiers
    urn:nbn:se:uu:diva-259178 (URN)10.1039/c5ta02136g (DOI)000357257900006 ()
    Funder
    Swedish Foundation for Strategic Research , RMA-110012SweGRIDS - Swedish Centre for Smart Grids and Energy StorageCarl Tryggers foundation StandUp
    Available from: 2015-07-29 Created: 2015-07-29 Last updated: 2020-02-18Bibliographically approved
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  • 844.
    Xu, Chao
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Non-aqueous Electrolytes and Interfacial Chemistry in Lithium-ion Batteries2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

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

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

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

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

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

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

    Place, publisher, year, edition, pages
    AMER CHEMICAL SOC, 2017
    National Category
    Physical Chemistry
    Identifiers
    urn:nbn:se:uu:diva-319530 (URN)10.1021/acs.chemmater.6b05247 (DOI)000396639400040 ()
    Funder
    Swedish Energy Agency, 34191-1 39036-1Swedish Foundation for Strategic Research Carl Tryggers foundation StandUp
    Available from: 2017-04-06 Created: 2017-04-06 Last updated: 2020-02-18Bibliographically approved
    2. The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/graphite Lithium-ion Batteries at Elevated Temperatures
    Open this publication in new window or tab >>The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/graphite Lithium-ion Batteries at Elevated Temperatures
    Show others...
    (English)Manuscript (preprint) (Other academic)
    Abstract
    National Category
    Natural Sciences
    Identifiers
    urn:nbn:se:uu:diva-320188 (URN)
    Funder
    StandUp
    Available from: 2017-04-17 Created: 2017-04-17 Last updated: 2018-01-03
    3. Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive
    Open this publication in new window or tab >>Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive
    Show others...
    2015 (English)In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 7, p. 2591-2599Article in journal (Refereed) Published
    Abstract [en]

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

    National Category
    Other Chemistry Topics
    Identifiers
    urn:nbn:se:uu:diva-253257 (URN)10.1021/acs.chemmater.5b00339 (DOI)000353176100041 ()
    Funder
    StandUp
    Available from: 2015-05-26 Created: 2015-05-25 Last updated: 2020-02-17Bibliographically approved
    4. A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
    Open this publication in new window or tab >>A hard X-ray photoelectron spectroscopy study on the solid electrolyte interphase of a lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide based electrolyte for Si-electrodes
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    2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 301, p. 105-112Article in journal (Refereed) Published
    Abstract [en]

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

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

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

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

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

    Available from: 2016-07-29 Created: 2016-07-29 Last updated: 2020-02-17Bibliographically approved
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  • 845.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry. Univ Cambridge, Dept Chem, Lensfield Rd, Cambridge CB2 1EW, England.
    Hernández, Guiomar
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Abbrent, Sabina
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Kober, Libor
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Konefal, Rafal
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Brus, Jiri
    Czech Acad Sci, Inst Macromol Chem, Heyrovskeho Nam 2, Prague 16206 6, Czech Republic.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Mindemark, Jonas
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Unraveling and Mitigating the Storage Instability of Fluoroethylene Carbonate-Containing LiPF6 Electrolytes To Stabilize Lithium Metal Anodes for High-Temperature Rechargeable Batteries2019In: ACS APPLIED ENERGY MATERIALS, ISSN 2574-0962, Vol. 2, no 7, p. 4925-4935Article in journal (Refereed)
    Abstract [en]

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

  • 846.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/graphite Lithium-ion Batteries at Elevated TemperaturesManuscript (preprint) (Other academic)
    Abstract
  • 847.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Jeschull, Fabian
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brant, William R.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    The Role of LiTDI Additive in LiNi1/3Mn1/3Co1/3O2/ Graphite Lithium-Ion Batteries at Elevated Temperatures2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, no 2, p. A40-A46Article in journal (Refereed)
    Abstract [en]

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

  • 848.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Lindgren, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Philippe, Bertrand
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Molecular and Condensed Matter Physics.
    Gorgoi, Mihaela
    Helmholtz Zentrum Berlin Germany.
    Björefors, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Improved Performance of the Silicon Anode for Li-Ion Batteries: Understanding the Surface Modification Mechanism of Fluoroethylene Carbonate as an Effective Electrolyte Additive2015In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 27, no 7, p. 2591-2599Article in journal (Refereed)
    Abstract [en]

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

  • 849.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Renault, Stevén
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ebadi, Mahsa
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Wang, Zhaohui
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Björklund, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Guyomard, Dominique
    Univ Nantes, CNRS, UMR 6502, Inst Mat Jean Rouxel IMN, F-44322 Nantes 3, France..
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjörn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    LiTDI: A Highly Efficient Additive for Electrolyte Stabilization in Lithium-Ion Batteries2017In: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 29, no 5, p. 2254-2263Article in journal (Refereed)
    Abstract [en]

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

  • 850.
    Xu, Chao
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Sun, Bing
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Gustafsson, Torbjorn
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Edström, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Brandell, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Hahlin, Maria
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Interface layer formation in solid polymer electrolyte lithium batteries: an XPS study2014In: JOURNAL OF MATERIALS CHEMISTRY A, ISSN 2050-7488, Vol. 2, no 20, p. 7256-7264Article in journal (Refereed)
    Abstract [en]

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

141516171819 801 - 850 of 912
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