The Experts below are selected from a list of 6228 Experts worldwide ranked by ideXlab platform
Maria Forsyth - One of the best experts on this subject based on the ideXlab platform.
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Cationic polymer-in-salt electrolytes for fast metal ion conduction and solid-state battery applications
Research Square Platform LLC, 2021Co-Authors: Fangfang Chen, Michel Armand, Xiaoen Wang, Maria ForsythAbstract:Abstract Polymer electrolytes provide a safe solution for all-solid-state high energy density batteries. Materials that meet the simultaneous requirement of high ionic conductivity and high Transference Number remain a challenge, in particular for new battery chemistries beyond Lithium such as Na, K and Mg. Herein, we demonstrate the versatility of a polymeric ionic liquid (PolyIL) as a solid-state solvent to achieve this goal for both Na and K. Using molecular simulations, we predict and elucidate fast metal ion transport in PolyILs through a structural diffusion mechanism in a polymer-in-salt environment, facilitating a high Transference Number. Experimental validation of these computational designed Na and K polymer electrolytes gives high ionic conductivities of 1.010-3 S cm-1 at 80 oC and an exceptional Na+ Transference Number of ~0.57. Electrochemical cycling of a sodium anode also demonstrates an ultra-low overpotential of 40 mV and stable long term performance of more than 100 hours in a symmetric cell. PolyIL-based polymer-in-salt strategies for novel solid-state electrolytes thus offer a promising route to design high performance next generation sustainable battery chemistries.
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na ion solvation and high Transference Number in superconcentrated ionic liquid electrolytes a theoretical approach
Journal of Physical Chemistry C, 2018Co-Authors: Fangfang Chen, Patrick C Howlett, Maria ForsythAbstract:Ionic liquids have been extensively studied for developing next-generation Li- and Na-ion batteries because they are potentially safer replacements for conventional organic solvents in liquid electrolytes. Some recent work has drawn our attention to high lithium and sodium salt concentration ionic liquid systems which demonstrate high alkali-metal-ion Transference Numbers and support cycling at high current densities. Here we present an in-depth theoretical study of ion dynamics in a concentrated room-temperature ionic liquid, N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ([C3mpyr][FSI]) with a sodium salt (NaFSI), focusing on how the solvation structure of a Na ion changes with salt concentration and how this affects its dynamics. These findings will help to understand the behavior of superconcentrated ionic liquid materials that will guide experimentalists in optimizing ionic liquid-based electrolyte materials.
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elucidation of transport mechanism and enhanced alkali ion Transference Numbers in mixed alkali metal organic ionic molten salts
Physical Chemistry Chemical Physics, 2016Co-Authors: Fangfang Chen, Maria ForsythAbstract:Mixed salts of Ionic Liquids (ILs) and alkali metal salts, developed as electrolytes for lithium and sodium batteries, have shown a remarkable ability to facilitate high rate capability for lithium and sodium electrochemical cycling. It has been suggested that this may be due to a high alkali metal ion Transference Number at concentrations approaching 50 mol% Li+ or Na+, relative to lower concentrations. Computational investigations for two IL systems illustrate the formation of extended alkali–anion aggregates as the alkali metal ion concentration increases. This tends to favor the diffusion of alkali metal ions compared with other ionic species in electrolyte solutions; behavior that has recently been reported for Li+ in a phosphonium ionic liquid, thus an increasing alkali Transference Number. The mechanism of alkali metal ion diffusion via this extended coordination environment present at high concentrations is explained and compared to the dynamics at lower concentrations. Heterogeneous alkali metal ion dynamics are also evident and, somewhat counter-intuitively, it appears that the faster ions are those that are generally found clustered with the anions. Furthermore these fast alkali metal ions appear to correlate with fastest ionic liquid solvent ions.
Masayoshi Watanabe - One of the best experts on this subject based on the ideXlab platform.
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solvent effects on li ion Transference Number and dynamic ion correlations in glyme and sulfolane based molten li salt solvates
Physical Chemistry Chemical Physics, 2020Co-Authors: Keisuke Shigenobu, Masayoshi Watanabe, Kaoru Dokko, Kazuhide UenoAbstract:The Li+ Transference Number of electrolytes is one of the key factors contributing to the enhancement in the charge–discharge performance of Li secondary batteries. However, a design principle to achieve a high Li+ Transference Number has not been established for liquid electrolytes. To understand the factors governing the Li+ Transference Number tLi, we investigated the influence of the ion–solvent interactions, Li ion coordination, and correlations of ion motions on the Li+ Transference Number in glyme (Gn, n = 1–4)- and sulfolane (SL)-based molten Li salt solvate electrolytes with lithium bis(trifluoromethansulfonyl)amide (LiTFSA). For the 1 : 1 tetraglyme-LiTFSA molten complex, [Li(G4)][TFSA], the Li+ Transference Number estimated using the potentiostatic polarisation method (tPPLi = 0.028) was considerably lower than that estimated using the self-diffusion coefficient data with pulsed filed gradient (PFG)-NMR (tNMRLi = 0.52). The dynamic ion correlations (i.e., cation–cation, anion–anion, and cation–anion cross-correlations) were determined from the experimental data on the basis of Roling and Bedrov's concentrated solution theory, and the results suggest that the strongly negative cross-correlations of the ion motions (especially for cation–cation motions) are responsible for the extremely low tPPLi of [Li(G4)][TFSA]. In contrast, tPPLi is larger than tNMRLi in the SL-based electrolytes. The high tPPLi of the SL-based electrolytes was ascribed to the substantially weaker anti-correlations of cation–cation and cation–anion motions. Whereas the translational motions of the long-lived [Li(glyme)]+ and [TFSA]− dominate the ionic conduction for [Li(G4)][TFSA], Li ion hopping/exchange conduction was reported to be prevalent in the SL-based electrolytes. The unique Li ion conduction mechanism is considered to contribute to the less correlated cation–cation and cation–anion motions in SL-based electrolytes.
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high Transference Number of na ion in liquid state sulfolane solvates of sodium bis fluorosulfonyl amide
Journal of Physical Chemistry C, 2020Co-Authors: Yukihiro Okamoto, Seiji Tsuzuki, Ryoichi Tatara, Kazuhide Ueno, Kaoru Dokko, Masayoshi WatanabeAbstract:The phase behavior, Na+ coordination structures, and transport and electrochemical properties of binary mixtures of NaN(SO2F)2 (NaFSA) and sulfolane (SL) solvent were investigated. The NaFSA and SL...
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high Transference Number of na ion in liquid state sulfolane solvates of sodium bis fluorosulfonyl amide
The Journal of Physical Chemistry, 2020Co-Authors: Yukihiro Okamoto, Seiji Tsuzuki, Ryoichi Tatara, Kazuhide Ueno, Kaoru Dokko, Masayoshi WatanabeAbstract:The phase behavior, Na⁺ coordination structures, and transport and electrochemical properties of binary mixtures of NaN(SO₂F)₂ (NaFSA) and sulfolane (SL) solvent were investigated. The NaFSA and SL form stable solvates at molar ratios [NaFSA]/[SL] = 1/3 and 1/0.5, and there is a crystallinity gap in the range 1/1.6 ≤ [NaFSA]/[SL] ≤ 1/0.8. In the crystals of both NaFSA–(SL)₃ and NaFSA–(SL)₀.₅, the solvent-bridged Na⁺–SL–Na⁺ and anion-bridged Na⁺–FSA–Na⁺ structures are formed. In the crystallinity gap, the mixtures remain liquid at room temperature and can be regarded as molten SL solvates of NaFSA. The Raman spectra of the molten solvates suggest that the solvent- and anion-bridged structures are partially maintained even in the liquid. However, Na⁺ ions exchange the ligands (solvent and anion) dynamically in the liquids. This significantly affects the Na⁺ ion transport in the liquids under an anion-blocking condition. The Na⁺ ion Transference Numbers (tNₐ₊) of molten solvates were estimated using symmetric Na/Na cells, and a molten solvate of [NaFSA]/[SL] = 1/1 exhibited a high tNₐ₊ of 0.8. Charge and discharge tests of a Na/Na₀.₄₄MnO₂ battery were performed with the molten solvate as the electrolyte. The rate capability of the battery was found to be significantly affected by tNₐ₊ in the electrolyte.
John Newman - One of the best experts on this subject based on the ideXlab platform.
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negative Transference Numbers in poly ethylene oxide based electrolytes
Journal of The Electrochemical Society, 2017Co-Authors: Ksenia Timachova, Danielle M Pesko, Rajashree Bhattacharya, Mackensie C Smith, Irune Villaluenga, John NewmanAbstract:Author(s): Pesko, DM; Timachova, K; Bhattacharya, R; Smith, MC; Villaluenga, I; Newman, J; Balsara, NP | Abstract: © The Author(s) 2017. Published by ECS. All rights reserved. The performance of battery electrolytes depends on three independent transport properties: ionic conductivity, diffusion coefficient, and Transference Number. While rigorous experimental techniques for measuring conductivity and diffusion coefficients are well-established, popular techniques for measuring the Transference Number rely on the assumption of ideal solutions. We employ three independent techniques for measuring Transference Number, t+, in mixtures of polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt. Transference Numbers obtained using the steady-state current method pioneered by Bruce and Vincent, t+,SS, and those obtained by pulsed-field gradient NMR, t+,NMR, are compared against a new approach detailed by Newman and coworkers, t+,Ne, for a range of salt concentrations. The latter approach is rigorous and based on concentrated solution theory, while the other two approaches only yield the true Transference Number in ideal solutions. Not surprisingly, we find that t+,SS and t+,NMR are positive throughout the entire salt concentration range, and decrease monotonically with increasing salt concentration. In contrast, t+,Ne has a non-monotonic dependence on salt concentration and is negative in the highly-concentrated regime. Our work implies that ion transport in PEO/LiTFSI electrolytes at high salt concentrations is dominated by the transport of ionic clusters.
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the measurement of a complete set of transport properties for a concentrated solid polymer electrolyte solution
Journal of The Electrochemical Society, 1995Co-Authors: Marc Doyle, Thomas F Fuller, Marca M Doeff, Lutgard C De Jonghe, John NewmanAbstract:Polymer electrolytes based on alkali metal salts in poly(ethylene oxides) are important for possible use in rechargeable batteries for both electric vehicle and consumer electronics applications. The authors measure a complete set of transport properties for one particular binary salt solution: sodium trifluoromethanesulfonate in poly(ethylene oxide), over a wide range of salt concentrations (0.1 to 2.6M) at 85 C. The properties measured include the conductivity, the salt diffusion coefficient, and the Na ion Transference Number. The mean molar activity coefficient of the salt is also determined. The conductivity and diffusion coefficients of NaCF{sub 3}SO{sub 3} are similar in magnitude to those of LiCF{sub 3}SO{sub 3} in (polyethylene oxide). The Transference Number and thermodynamic factor are found by combining concentration cell data with the results of galvanostatic polarization experiments. A theoretical analysis of the experimental method based on concentrated-solution theory is given. The study verifies that the Transference Numbers derived from the experiments retain fundamental significance in applications involving both steady and transient processes and in systems coupling the polymer electrolyte with electrodes of all types (stoichiometries). The relevant Transference Numbers can be determined independently of any knowledge of speciation of the polymer electrolyte. The Transference Numbers found here for themore » sodium ion are much lower than those reported for the lithium ion, especially in the concentrated solutions. The Transference Number of the sodium ion is negative in the more concentrated solutions and levels off at its maximum value of 0.31 in the dilute concentration range. The Transference Number results are interpreted in terms of complexation of the sodium ion with the anionic species.« less
Bruno Scrosati - One of the best experts on this subject based on the ideXlab platform.
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composite peon natfsi polymer electrolyte preparation thermal and electrochemical characterization
Journal of Power Sources, 2014Co-Authors: Serra J Moreno, Marc B Berman, Steven G. Greenbaum, Bruno Scrosati, Michel Armand, Stefania PaneroAbstract:Abstract Membranes of sodium bis(trifluoromethanesulfonate) imide (NaTFSI) complexed with poly(ethylene oxide) (PEO) salt have been prepared by a solvent-free hot-pressing technique with different EO:Na molar ratio. All membranes show good ionic conductivities in the range of 10 −3 S cm −1 above 70 °C. However, the more NaTFSI-concentrated samples are sticky gums due to the plasticizing nature of the anion. The PEO 20 :NaTFSI sample exhibits the compromise of conductivity, thermal and mechanical properties. The addition of nanometric SiO 2 to the PEO 20 :NaTFSI membranes further enhances their mechanical properties. Moreover, the PEO 20 :NaTFSI + 5 wt.% SiO 2 membranes show similar ionic conductivity and similar anodic electrochemical stability in comparison to the ceramic free PEO 20 :NaTFSI sample. In a Na (s) /polymer electrolyte/Na (s) symmetrical cell followed up to 30 days, the presence of the ceramic filler slightly increased the interface resistance in comparison to the ceramic-free membrane. Nuclear magnetic resonance determinations of anion diffusion coefficients and Na + mobility suggest that presence of filler may have a positive affect on the cation Transference Number that is in accordance with the t Na + Transference Number measurement.
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Enhancement of ion transport in polymer electrolytes by addition of nanoscale inorganic oxides
Journal of Power Sources, 2001Co-Authors: S.h. Chung, Bruno Scrosati, L Persi, Y. Wang, Fausto Croce, Steve Greenbaum, Edward J PlichtaAbstract:Abstract The effect of addition of nanoparticle inorganic oxides to poly(ethylene oxide) (PEO) complexed with LiClO 4 on cation transport properties has been explored by electrochemical and 7 Li nuclear magnetic resonance (NMR) methods. The presence of the nanoparticles generally increases the ionic conductivity and the cation Transference Number, the effect being greatest for TiO 2 . The enhancement in cation Transference Number is directly correlated with increased Li diffusivity measured by NMR. The NMR results also demonstrate that the increased ionic conductivity is not attributable to a corresponding increase in polymer segmental motion, but more likely a weakening of the polyether-cation association induced by the nanoparticles.
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role of the ceramic fillers in enhancing the transport properties of composite polymer electrolytes
Electrochimica Acta, 2001Co-Authors: F Croce, Bruno Scrosati, L Persi, F Serrainofiory, Edward J Plichta, Mary A HendricksonAbstract:A model to account for the role of the ceramic fillers in enhancing the transport properties of PEO-based composite polymer electrolytes is here proposed. The model is supported by a series of specifically addressed electrochemical tests which included the determination of the conductivity and of the lithium Transference Number of various composite electrolyte samples differing from the type of the surface states of the ceramic filler.
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impedance spectroscopy study of peo based nanocomposite polymer electrolytes
Journal of The Electrochemical Society, 2000Co-Authors: Bruno Scrosati, F Croce, L PersiAbstract:The addition of nanometric fillers (e.g., , ) to polymer electrolytes induces consistent improvement in the transport properties. The increase in conductivity and in the cation Transference Number is attributed to the enhancement of the degree of the amorphous phase in the polymer matrix, as well as to some acid‐base Lewis type, ceramic‐electrolyte interactions. This model is confirmed by results obtained from a detailed impedance spectroscopy study carried out on poly(ethylene oxide) [P(EO)]‐based polymer electrolyte samples with and without ceramic fillers. © 2000 The Electrochemical Society. All rights reserved.
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kinetics and stability of the lithium electrode in poly methylmethacrylate based gel electrolytes
Electrochimica Acta, 1995Co-Authors: Giovanni Battista Appetecchi, F Croce, Bruno ScrosatiAbstract:Abstract The transport and electrochemical properties of gel-type ionic conducting membranes formed by immobilizing liquid solutions of lithium salts in a poly(methylmethacrylate) matrix have been determined. In particular, the conductivity, the lithium ion Transference Number and the electrochemical stability window are evaluated and discussed. Finally, particular attention is devoted to the phenomena occuring at the interface between these ionic membranes and the lithium metal electrode.
Kaoru Dokko - One of the best experts on this subject based on the ideXlab platform.
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solvent effects on li ion Transference Number and dynamic ion correlations in glyme and sulfolane based molten li salt solvates
Physical Chemistry Chemical Physics, 2020Co-Authors: Keisuke Shigenobu, Masayoshi Watanabe, Kaoru Dokko, Kazuhide UenoAbstract:The Li+ Transference Number of electrolytes is one of the key factors contributing to the enhancement in the charge–discharge performance of Li secondary batteries. However, a design principle to achieve a high Li+ Transference Number has not been established for liquid electrolytes. To understand the factors governing the Li+ Transference Number tLi, we investigated the influence of the ion–solvent interactions, Li ion coordination, and correlations of ion motions on the Li+ Transference Number in glyme (Gn, n = 1–4)- and sulfolane (SL)-based molten Li salt solvate electrolytes with lithium bis(trifluoromethansulfonyl)amide (LiTFSA). For the 1 : 1 tetraglyme-LiTFSA molten complex, [Li(G4)][TFSA], the Li+ Transference Number estimated using the potentiostatic polarisation method (tPPLi = 0.028) was considerably lower than that estimated using the self-diffusion coefficient data with pulsed filed gradient (PFG)-NMR (tNMRLi = 0.52). The dynamic ion correlations (i.e., cation–cation, anion–anion, and cation–anion cross-correlations) were determined from the experimental data on the basis of Roling and Bedrov's concentrated solution theory, and the results suggest that the strongly negative cross-correlations of the ion motions (especially for cation–cation motions) are responsible for the extremely low tPPLi of [Li(G4)][TFSA]. In contrast, tPPLi is larger than tNMRLi in the SL-based electrolytes. The high tPPLi of the SL-based electrolytes was ascribed to the substantially weaker anti-correlations of cation–cation and cation–anion motions. Whereas the translational motions of the long-lived [Li(glyme)]+ and [TFSA]− dominate the ionic conduction for [Li(G4)][TFSA], Li ion hopping/exchange conduction was reported to be prevalent in the SL-based electrolytes. The unique Li ion conduction mechanism is considered to contribute to the less correlated cation–cation and cation–anion motions in SL-based electrolytes.
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high Transference Number of na ion in liquid state sulfolane solvates of sodium bis fluorosulfonyl amide
Journal of Physical Chemistry C, 2020Co-Authors: Yukihiro Okamoto, Seiji Tsuzuki, Ryoichi Tatara, Kazuhide Ueno, Kaoru Dokko, Masayoshi WatanabeAbstract:The phase behavior, Na+ coordination structures, and transport and electrochemical properties of binary mixtures of NaN(SO2F)2 (NaFSA) and sulfolane (SL) solvent were investigated. The NaFSA and SL...
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high Transference Number of na ion in liquid state sulfolane solvates of sodium bis fluorosulfonyl amide
The Journal of Physical Chemistry, 2020Co-Authors: Yukihiro Okamoto, Seiji Tsuzuki, Ryoichi Tatara, Kazuhide Ueno, Kaoru Dokko, Masayoshi WatanabeAbstract:The phase behavior, Na⁺ coordination structures, and transport and electrochemical properties of binary mixtures of NaN(SO₂F)₂ (NaFSA) and sulfolane (SL) solvent were investigated. The NaFSA and SL form stable solvates at molar ratios [NaFSA]/[SL] = 1/3 and 1/0.5, and there is a crystallinity gap in the range 1/1.6 ≤ [NaFSA]/[SL] ≤ 1/0.8. In the crystals of both NaFSA–(SL)₃ and NaFSA–(SL)₀.₅, the solvent-bridged Na⁺–SL–Na⁺ and anion-bridged Na⁺–FSA–Na⁺ structures are formed. In the crystallinity gap, the mixtures remain liquid at room temperature and can be regarded as molten SL solvates of NaFSA. The Raman spectra of the molten solvates suggest that the solvent- and anion-bridged structures are partially maintained even in the liquid. However, Na⁺ ions exchange the ligands (solvent and anion) dynamically in the liquids. This significantly affects the Na⁺ ion transport in the liquids under an anion-blocking condition. The Na⁺ ion Transference Numbers (tNₐ₊) of molten solvates were estimated using symmetric Na/Na cells, and a molten solvate of [NaFSA]/[SL] = 1/1 exhibited a high tNₐ₊ of 0.8. Charge and discharge tests of a Na/Na₀.₄₄MnO₂ battery were performed with the molten solvate as the electrolyte. The rate capability of the battery was found to be significantly affected by tNₐ₊ in the electrolyte.
