The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform

Doron Aurbach - One of the best experts on this subject based on the ideXlab platform.

  • on the oxidation state of manganese ions in li ion battery Electrolyte solutions
    Journal of the American Chemical Society, 2017
    Co-Authors: Anjan Banerjee, Doron Aurbach, Yuliya Shilina, Baruch Ziv, Joseph M Ziegelbauer, Shalom Luski, Ion C Halalay
    Abstract:

    We demonstrate herein that Mn3+ and not Mn2+, as commonly accepted, is the dominant dissolved manganese cation in LiPF6-based Electrolyte solutions of Li-ion batteries with lithium manganate spinel positive and graphite negative electrodes chemistry. The Mn3+ fractions in solution, derived from a combined analysis of electron paramagnetic resonance and inductively coupled plasma spectroscopy data, are ∼80% for either fully discharged (3.0 V hold) or fully charged (4.2 V hold) cells, and ∼60% for galvanostatically cycled cells. These findings agree with the average oxidation state of dissolved Mn ions determined from X-ray absorption near-edge spectroscopy data, as verified through a speciation diagram analysis. We also show that the fractions of Mn3+ in the aprotic Nonaqueous Electrolyte solution are constant over the duration of our experiments and that disproportionation of Mn3+ occurs at a very slow rate.

  • oxidation of dimethyl sulfoxide solutions by electrochemical reduction of oxygen
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Daniel Sharon, Michal Afri, Malachi Noked, Arnd Garsuch, Aryeh A Frimer, Doron Aurbach
    Abstract:

    Oxygen reduction in Nonaqueous Electrolyte solutions containing Li salts is a complex field of research involving solution reactions with oxygen radicals and lithium oxides. The aprotic polar solve...

  • oxidation of dimethyl sulfoxide solutions by electrochemical reduction of oxygen
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Daniel Sharon, Michal Afri, Malachi Noked, Arnd Garsuch, Aryeh A Frimer, Doron Aurbach
    Abstract:

    Oxygen reduction in Nonaqueous Electrolyte solutions containing Li salts is a complex field of research involving solution reactions with oxygen radicals and lithium oxides. The aprotic polar solvent dimethyl sulfoxide presents itself as a most promising candidate for a durable Electrolyte for use in lithium–oxygen batteries. In the present study, we detail our in-depth study on dimethyl sulfoxide (DMSO) stability in the presence of electroactive lithium oxygen species on carbon electrodes. The question of the stability of DMSO is magnified by our use of carbon-fiber electrodes, which have relatively high specific surface-area and utilize low volumes of Electrolyte solutions. This configuration has enabled us to identify even minor side-products such as LiOH, dimethyl sulfone, Li2SO3 and Li2SO4. The proposed mechanism of DMSO decomposition is supported by analytical measurements. These analyses confirm that during the reduction of oxygen on carbon electrodes, the solvent undergoes oxidation by reactive ox...

  • morphological and structural studies of composite sulfur electrodes upon cycling by hrtem afm and raman spectroscopy
    Journal of The Electrochemical Society, 2010
    Co-Authors: Ran Elazari, Gregory Salitra, Y Talyosef, Judith Grinblat, Charislea Scordiliskelley, Ang Xiao, John Affinito, Doron Aurbach
    Abstract:

    In this work, structural and morphological changes in composite sulfur electrodes were studied due to their cycling in rechargeable Li-S cells produced by Sion Power Inc. Composite sulfur cathodes, comprising initially elemental sulfur and carbon, undergo pronounced structural and morphological changes during discharge-charge cycles due to the complicated redox behavior of sulfur in Nonaqueous Electrolyte solutions that contain Li ions. Nevertheless, Li―S cells can demonstrate prolonged cycling. To advance this technology, it is highly important to understand the evolution of the structure and morphology of sulfur cathodes as cycling proceeds. High resolution scanning and tunneling microscopy, scanning probe microscopy, and Raman spectroscopy were used in conjunction with the electrochemical measurements. A special methodology for slicing composite sulfur electrodes and their cross sectioning and depth profiling was developed. The gradual changes in the structure of sulfur cathodes due to cycling is described and discussed herein. Important phenomena include changes in the surface electrical conductivity of sulfur electrodes and pronounced morphological changes due to the irreversibility of the sulfur redox reactions. Based on the observations presented in this work, it may be possible to outline guidelines for improving Li-S battery technology and extending its cycle life.

Zhichang Wang - One of the best experts on this subject based on the ideXlab platform.

  • relationship among the raoult law zdanovskii stokes robinson rule and two extended zdanovskii stokes robinson rules of wang
    Journal of Chemical & Engineering Data, 2009
    Co-Authors: Zhichang Wang
    Abstract:

    In this paper, the Raoult law (C. R. Acad. Sci. Ser. C 1887, 104, 1430), the Zdanovskii−Stokes−Robinson (ZSR) rule (Trudy Solyanoi Laboratorii Akad. Nauk SSSR 1936, No. 6, 5; J. Phys. Chem. 1966, 70, 2126), and two extended ZSR rules of Wang (Acta Metall. Sinica 1980, 16, 195; Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1045) are presented in a unified way. Similar to the Raoult law, which was first noted empirically in pyridine solutions, the ZSR rule for isopiestic mixed Electrolyte and nonElectrolyte aqueous solutions can be extended to every kind of liquid and solid solutions such as organic mixtures, aqueous and Nonaqueous Electrolyte and nonElectrolyte solutions, liquid and solid alloys, molten salt mixtures, slags, and nonstoichiometric solid solutions, resulting in two extended ZSR rules of Wang. Although the solutions obeying the Raoult law (or the related classically ideal solution model) are very few as compared with the classically nonideal solutions, one classically ideal solution {B+C+...+Z} may...

Daniel Sharon - One of the best experts on this subject based on the ideXlab platform.

  • oxidation of dimethyl sulfoxide solutions by electrochemical reduction of oxygen
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Daniel Sharon, Michal Afri, Malachi Noked, Arnd Garsuch, Aryeh A Frimer, Doron Aurbach
    Abstract:

    Oxygen reduction in Nonaqueous Electrolyte solutions containing Li salts is a complex field of research involving solution reactions with oxygen radicals and lithium oxides. The aprotic polar solve...

  • oxidation of dimethyl sulfoxide solutions by electrochemical reduction of oxygen
    Journal of Physical Chemistry Letters, 2013
    Co-Authors: Daniel Sharon, Michal Afri, Malachi Noked, Arnd Garsuch, Aryeh A Frimer, Doron Aurbach
    Abstract:

    Oxygen reduction in Nonaqueous Electrolyte solutions containing Li salts is a complex field of research involving solution reactions with oxygen radicals and lithium oxides. The aprotic polar solvent dimethyl sulfoxide presents itself as a most promising candidate for a durable Electrolyte for use in lithium–oxygen batteries. In the present study, we detail our in-depth study on dimethyl sulfoxide (DMSO) stability in the presence of electroactive lithium oxygen species on carbon electrodes. The question of the stability of DMSO is magnified by our use of carbon-fiber electrodes, which have relatively high specific surface-area and utilize low volumes of Electrolyte solutions. This configuration has enabled us to identify even minor side-products such as LiOH, dimethyl sulfone, Li2SO3 and Li2SO4. The proposed mechanism of DMSO decomposition is supported by analytical measurements. These analyses confirm that during the reduction of oxygen on carbon electrodes, the solvent undergoes oxidation by reactive ox...

Rika Hagiwara - One of the best experts on this subject based on the ideXlab platform.

  • application of low viscosity ionic liquid to the Electrolyte of double layer capacitors
    Journal of The Electrochemical Society, 2003
    Co-Authors: Makoto Ue, Masayuki Takeda, Akiko Toriumi, Asao Kominato, Rika Hagiwara
    Abstract:

    The performance of a double-layer capacitor (DLC) composed of activated carbon electrodes and 1--ethyl-3-methylimidazolium fluoride (EMIF).2.3HF, which has extremely high conductivity with low viscosity, was examined and compared with those using the popular ionic liquid EMIBF 4 , conventional aqueous Electrolyte 35 wt % H 2 SO 4 , and Nonaqueous Electrolyte 1 M Et 3 MeNBF 4 /propylene carbonate. The DLC using EMIF.2.3HF showed an intermediate capacitance and internal resistance between the aqueous and Nonaqueous Electrolyte systems due to its intermediate double-layer capacitance and electrolytic conductivity. EMIF.2.3HF afforded much higher capacitance than EMIBF 4 even at low temperatures, however, it had a lower decomposition voltage (∼2 V), resulting in lower energy density. The capacitance of EMIF.2.3HF was extremely dependent on the applied voltage.

  • application of low viscosity ionic liquid to the Electrolyte of double layer capacitors
    Journal of The Electrochemical Society, 2003
    Co-Authors: Masayuki Takeda, Akiko Toriumi, Asao Kominato, Rika Hagiwara, Yasuhiko Ito
    Abstract:

    The performance of a double-layer capacitor (DLC) composed of activated carbon electrodes and 1--ethyl-3-methylimidazolium fluoride (EMIF).2.3HF, which has extremely high conductivity with low viscosity, was examined and compared with those using the popular ionic liquid EMIBF 4 , conventional aqueous Electrolyte 35 wt % H 2 SO 4 , and Nonaqueous Electrolyte 1 M Et 3 MeNBF 4 /propylene carbonate. The DLC using EMIF.2.3HF showed an intermediate capacitance and internal resistance between the aqueous and Nonaqueous Electrolyte systems due to its intermediate double-layer capacitance and electrolytic conductivity. EMIF.2.3HF afforded much higher capacitance than EMIBF 4 even at low temperatures, however, it had a lower decomposition voltage (∼2 V), resulting in lower energy density. The capacitance of EMIF.2.3HF was extremely dependent on the applied voltage.

Martin Z Bazant - One of the best experts on this subject based on the ideXlab platform.

  • performance and degradation of a lithium bromine rechargeable fuel cell using highly concentrated catholytes
    Electrochimica Acta, 2016
    Co-Authors: Peng Bai, Martin Z Bazant
    Abstract:

    Abstract Lithium-air batteries have been considered as ultimate solutions for the power source of long-range electrified transportation, but state-of-the-art prototypes still suffer from short cycle life, low efficiency and poor power output. Here, a lithium-bromine rechargeable fuel cell using highly concentrated bromine catholytes is demonstrated with comparable specific energy, improved power density, and higher efficiency. The cell is similar in structure to a hybrid-Electrolyte Li-air battery, where a lithium metal anode in Nonaqueous Electrolyte is separated from aqueous bromine catholytes by a lithium-ion conducting ceramic plate. The cell with a flat graphite electrode can discharge at a peak power density around 9 mW cm−2 and in principle could provide a specific energy of 791.8 Wh kg−1, superior to most existing cathode materials and catholytes. It can also run in the regenerative mode to recover the lithium metal anode and free bromine with 80-90% voltage efficiency, without any catalysts. Degradation of the solid Electrolyte and the evaporation of bromine during deep charging are challenges that should be addressed in improved designs to fully exploit the high specific energy of the liquid bromine. The proposed system offers a potential power source for long-range electric vehicles, beyond current Li-ion batteries yet close to envisioned Li-air batteries.

  • performance and degradation of a lithium bromine rechargeable fuel cell using highly concentrated catholytes
    arXiv: Chemical Physics, 2016
    Co-Authors: Peng Bai, Martin Z Bazant
    Abstract:

    Lithium-air batteries have been considered as ultimate solutions for the power source of long-range electrified transportation, but state-of-the-art prototypes still suffer from short cycle life, low efficiency and poor power output. Here, a lithium-bromine rechargeable fuel cell using highly concentrated bromine catholytes is demonstrated with comparable specific energy, improved power density, and higher efficiency. The cell is similar in structure to a hybrid-Electrolyte Li-air battery, where a lithium metal anode in Nonaqueous Electrolyte is separated from aqueous bromine catholytes by a lithium-ion conducting ceramic plate. The cell with a flat graphite electrode can discharge at a peak power density around 9mW cm-2 and in principle could provide a specific energy of 791.8 Wh kg-1, superior to most existing cathode materials and catholytes. It can also run in regenerative mode to recover the lithium metal anode and free bromine with 80-90% voltage efficiency, without any catalysts. Degradation of the solid Electrolyte and the evaporation of bromine during deep charging are challenges that should be addressed in improved designs to fully exploit the high specific energy of liquid bromine. The proposed system offers a potential power source for long-range electric vehicles, beyond current Li-ion batteries yet close to envisioned Li-air batteries.