Spectral deconvolution in electrophoretic NMR to investigate the migration of neutral molecules in electrolytes

Schmidt, Franz; Pugliese, Andrea; Santini, Catherine C.; Castiglione, Franca; Schönhoff, Monika

doi:10.1002/mrc.4978

Cited by 28 publications

(62 citation statements)

References 45 publications

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“…For mole fractions in the middle of the composition range (0.3 < < 0.8), the situation is rather complex, with no single phase adjustment adequately correcting all the peaks, simultaneously, evidenced in terms of the slight negative intensity around 2.5 -3.0 ppm, the middle spectra in figure 7. Whilst elegant methods to deconvolute such overlapping spectra in electrophoretic NMR experiments have recently been presented, the spectra here do not lend themselves to that level of scrutiny, and a semi-empirical analysis is presented [ 59 ].…”

Section: Resultsmentioning

confidence: 99%

Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

et al. 2020

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Coacervation is widely used in formulations to induce a beneficial character to the formulation but non-equilibrium effects are often manifest. Electrophoretic (eNMR), pulsedgradient spin-echo NMR (PGSE-NMR) and small-angle neutron scattering (SANS) have been used to quantify the interaction between low molecular cationic poly(diallyldimethylammonium chloride) (PDADMAC) and the anionic surfactant sodium dodecylsulphate (SDS) in aqueous solution as a model for the precursor state to such nonequilibrium processes. The NMR data show that within the low surfactant concentration onephase region, an increasing surfactant concentration leads to a reduction in the charge on the polymer and a collapse of its solution conformation, attaining minimum values coincident with the macroscopic phase separation boundary. Interpretation of the scattering data reveals how the rod-like polymer changes over the same surfactant concentration window, with no discernible fingerprint of micellar type aggregates, rather the emergence of disc-like and lamellar structures. At the highest surfactant concentration, the emergence of a weak Bragg peak in both the polymer and surfactant scattering suggest these pre-cursor disc and lamellar structures evolve into paracrystalline stacks which ultimately phase separate. Addition of the non-ionic surfactant hexa(ethylene oxide) dodecyl ether (C12E6) to the system seems to have little effect on the PDADMAC/SDS interaction as determined by NMR, merely displacing the

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Section: Resultsmentioning

confidence: 99%

Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

et al. 2020

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“…Overcoming various experimental challenges, eNMR has recently been applied to various classes of concentrated electrolytes. These include pure ILs, [ 19,20 ] Li‐salt in IL, [ 21,22 ] solvate IL based on glyme, [ 23,24 ] and salt‐in‐polymer electrolytes. [ 25–27 ] eNMR on Li salt in IL systems has provided insight into the dominating transport mechanism, which is a correlated migration of Li with several anions.…”

Section: Introductionmentioning

confidence: 99%

Ionic Liquid in Li Salt Electrolyte: Modifying the Li⁺ Transport Mechanism by Coordination to an Asymmetric Anion

Brinkkötter

Mariani

Jeong

et al. 2020

Adv Energy and Sustain Res

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In binary ionic liquid/Li salt electrolytes for lithium‐ion batteries the use of asymmetric anions reduces the tendency for crystallization and enables liquid systems with high Li concentration. The ionic liquid composed of the N‐(methoxyethyl)‐N‐methylpyrrolidinium (Pyr12O1) cation and the (fluorosulfonyl)(trifluoromethanesulfonyl)imide (FTFSI) asymmetric anion at molar Li FTFSI fractions up to 0.6 are investigated by 19F and 7Li chemical shifts, 1H, 19F, and 7Li electrophoretic nuclear magnetic resonance (NMR) and density functional theory (DFT) calculations. Thereby, the local coordination environment of Li is elucidated and correlated with the Li+ ion transport properties. At low Li salt fraction, the preferred Li+ coordination is to the trifluoromethanesulfonyl side of the anion, resulting in vehicular Li+ transport in stable, net negatively charged Li‐anion clusters causing negative Li transference numbers. The Li coordination is, however, shifting to the fluorosulfonyl group at salt fractions >0.4, as consistently evidenced by DFT and 19F NMR. Herein, Li+ mobilities give evidence of an increasing relevance of structural Li+ ion transport, which is key toward developing efficient ionic liquid–based batteries. This knowledge will serve further tailored design of cations and anions, which reduces crystallization and promote structural transport in ionic liquids for safe and high‐power batteries.

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“…The phase angle was determined by fits of the spectra with phase sensitive Lorentzian profiles as described elsewhere. [ 21 ] The electrophoretic mobility was finally obtained from the slope of the linear regression in a plot of the phase shift as a function of the gradient strength according to Equation (). Mobilities were averaged over at least three independent measurements.…”

Section: Methodsmentioning

confidence: 99%

Polymer‐Induced Inversion of the Li⁺ Drift Direction in Ionic Liquid‐Based Ternary Polymer Electrolytes

Rosenwinkel

Schönhoff

2021

Macro Chemistry & Physics

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While salt-in-ionic liquid (IL) electrolytes provide a promising alternative to organic electrolytes, they suffer from large ionic clusters impeding lithium ion transport. Here, a lithium-coordinating polymer is added and the transition from salt-in-IL to IL-based ternary polymer gel electrolytes is followed, investigating the influence of the composition on Li transport mechanisms. The electrolyte is composed of the salt lithium bis(trifluoromethanesulfonyl)amide (LiTFSA), the IL 1-butyl-1-methylpyrrolidinium (Pyr 14 ) TFSA, and a variable amount of poly(ethylene oxide) (PEO). Impedance spectroscopy, multinuclear ( 1 H, 7 Li, and 19 F) diffusion NMR and electrophoretic NMR (eNMR) yield electrophoretic mobilities, transference numbers, partial conductivities, and effective charges of all ionic species. As the polymer fraction increases, the lithium ion drift direction is inverted. The sign reversal of Li + mobility and transference number occurs at the optimum coordination of 5-6 ethylene oxide units per Li + ion. The dominant Li + transport mechanism shifts from a vehicular transport via anionic clusters to chain-dominated transport mechanisms. It is concluded that the lithium transport properties of IL-based electrolytes can be vastly improved by the addition of PEO. Tuning the composition of the ternary electrolyte reveals optimal Li + transport properties at moderately high polymer contents as well as high salt concentrations.

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Spectral deconvolution in electrophoretic NMR to investigate the migration of neutral molecules in electrolytes

Cited by 28 publications

References 45 publications

Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

Ionic Liquid in Li Salt Electrolyte: Modifying the Li⁺ Transport Mechanism by Coordination to an Asymmetric Anion

Polymer‐Induced Inversion of the Li⁺ Drift Direction in Ionic Liquid‐Based Ternary Polymer Electrolytes

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Spectral deconvolution in electrophoretic NMR to investigate the migration of neutral molecules in electrolytes

Cited by 28 publications

References 45 publications

Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

Interaction of Low Molecular Weight Poly(diallyldimethylammonium chloride) and Sodium Dodecyl Sulfate in Low Surfactant–Polyelectrolyte Ratio, Salt-Free Solutions

Ionic Liquid in Li Salt Electrolyte: Modifying the Li+ Transport Mechanism by Coordination to an Asymmetric Anion

Polymer‐Induced Inversion of the Li+ Drift Direction in Ionic Liquid‐Based Ternary Polymer Electrolytes

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Product

Resources

About

Ionic Liquid in Li Salt Electrolyte: Modifying the Li⁺ Transport Mechanism by Coordination to an Asymmetric Anion

Polymer‐Induced Inversion of the Li⁺ Drift Direction in Ionic Liquid‐Based Ternary Polymer Electrolytes