Browsing by Author "Sujeet Kumar Chaurasia"

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Cation-Cation, Cation-Anion, and Anion-Anion Translation Diffusion in Ionic Liquids─Insight from NMR Relaxometry
(American Chemical Society, 2025) Elzbieta Masiewicz; Roksana Markiewicz; Rajendra K. Singh; Sujeet Kumar Chaurasia; Danuta Kruk
1H and 19F spin-lattice relaxation experiments have been performed for a series of ionic liquids: [HMIM][TFSI], [OMIM][TFSI], and [DMIM][TFSI] including the same anion and cations with progressively longer alkyl chains. The experiments were performed in a wide frequency range from 10 kHz to 10 MHz (referring to the 1H resonance frequency) versus temperature. This extensive data set has been analyzed in terms of a theoretical model including all relevant homonuclear (1H-1H and 19F-19F) and heteronuclear (1H-19F) relaxation pathways and linking the relaxation features to the relative translational diffusion between the ion pairs (cation-cation, cation-anion, and anion-anion). In addition to the comprehensive theoretical approach, closed-form expressions have been provided and applied to determine the diffusion coefficients from the slopes of the linear dependences of the relaxation rates on the square root of the resonance frequency. The combined experimental and theoretical studies have led to the determination of the complete set of diffusion coefficients, forming a consistent picture of the dynamical scenario. In addition to revealing the dynamical properties of the liquids and the influence of the subtle changes in the cation structure on the movement of both cations and anions, the theoretical means for exploiting Nuclear Magnetic Resonance relaxometry for ionic liquids have been provided. © 2024 American Chemical Society.
Development of ionic liquid mediated novel polymer electrolyte membranes for application in Na-ion batteries
(Royal Society of Chemistry, 2016) Varun Kumar Singh; Shalu; Sujeet Kumar Chaurasia; Rajendra Kumar Singh
Polymer electrolyte membranes based on polymer PEO, ionic liquid, 1-butyl-3-methylimidazolium methylsulfate, BMIM-MS, and salt, sodium methylsulfate, NaMS, {PEO + x wt% BMIM-MS for x = 0 and 20 and (PEO + 10 wt% of NaMS) + x wt% BMIM-MS for x = 0, 20 and 60} were prepared and characterized by various experimental techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA)/differential thermogravimetric analysis (DTGA), differential scanning calorimetry (DSC), ac impedance spectroscopy and cyclic voltammetry (CV). The synthesized polymer electrolyte membranes were free-standing and flexible with good mechanical stability. A Fourier transform infrared spectroscopic (FTIR) study showed the complexation of ether oxygen of the PEO backbone with the cations of the Na-salt or IL (BMIM-MS). SEM, XRD and DSC studies show that the crystallinity of the polymer electrolyte membranes decreases on increasing the concentration of IL due to the plasticization effect of the IL. Ionic conductivity of polymer electrolyte membranes was found to increase with the concentration of IL (BMIM-MS) and showed a maximum room temperature (at ∼30°C) ionic conductivity of ∼1.05 × 10-4 S cm-1 for 60 wt% IL loading. The plasticization effect of the IL enhanced the amorphicity of the polymeric membranes. This optimized composition of polymer electrolyte shows high electrochemical potential window (∼4-5 V), cationic transference number (i.e. tNa+ ∼ 0.46) and also good cycling between ∼2.7 and ∼1.6 V through charging-discharging. © The Royal Society of Chemistry 2016.
Dynamical properties of EMIM-SCN confined in a SiO2 matrix by means of 1H NMR relaxometry
(Royal Society of Chemistry, 2017) Danuta Kruk; Milosz Wojciechowski; Yogendra Lal Verma; Sujeet Kumar Chaurasia; Rajendra Kumar Singh
1H nuclear magnetic resonance relaxometry is applied to investigate the translational and rotational dynamics of ionogels composed of an ionic liquid (IL): 1-ethyl-3-methyl-imidazolium-thiocyanate (EMIM-SCN) confined in a nanoporous SiO2 matrix. The relaxation studies were performed in the frequency range of 4 kHz-40 MHz and the temperature range of 223-248 K for different concentrations of the IL; the ratio (no. of moles of IL/no. of moles of SiO2) yields: 1/2, 3/5 and 7/10. A thorough analysis of this large set of experimental data was performed assuming the existence of two fractions of the liquid: a core fraction (near the pore center) and a surface fraction (near the confining walls). It was shown for all concentrations that the confinement does not significantly affect the translational motion near the pore center compared to the dynamics in bulk. The diffusion coefficients in the surface fraction are considerably smaller compared to the core fraction (from one to two orders of magnitude) and the difference becomes larger with increasing temperature. The diffusion coefficients become smaller for higher concentrations-this effect is not large, but visible. Very importantly, it was shown that, despite the interactions with the surface, the diffusion in the surface fraction remains of 3D character. As far as rotational dynamics in the surface fraction is concerned, it slows down compared to the bulk (and the core fraction), but this effect is of the order of factor 2-3. © the Owner Societies 2017.
Dynamics of ionic liquid-polymer gel membranes—Insight from NMR relaxometry for [BMIM][BF4]-PVDF-HFP systems
(American Institute of Physics, 2024) Shitanshu Pratap Singh; Elżbieta Masiewicz; Rajendra Kumar Singh; Sujeet Kumar Chaurasia; Danuta Kruk
1H spin-lattice relaxation experiments have been performed for ionic liquid-polymer gel membranes, including 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) with different proportions. The experiments have been performed in a broad range of resonance frequencies (from about 5 Hz to 40 MHz) vs temperature and complemented with analogous studies for [BMIM][BF4] in bulk as a reference. A model of the relaxation processes in the membranes has been proposed. The model includes two relaxation contributions. One of them corresponds to the concept of restricted, two-dimensional translation diffusion with a residence lifetime, while the second one has the form characteristic of polymers (mathematically similar to the limiting behavior of two-dimensional translation diffusion with a very long residence lifetime). The extensive dataset has been consistently interpreted in terms of the model, revealing two dynamical processes on the time scales of 10−7 s (for the second relaxation contribution) and 10−9 s (for the first one). The relationship of these relaxation contributions to the motion of the polymer or ionic liquid-polymer complexes and to the translation diffusion of BMIM cations in the matrix has been discussed. © 2024 Author(s).
Effect of phosphonium based ionic liquid on structural, electrochemical and thermal behaviour of polymer poly(ethylene oxide) containing salt lithium bis(trifluoromethylsulfonyl)imide
(Royal Society of Chemistry, 2016) Himani Gupta; Shalu; Liton Balo; Varun Kumar Singh; Sujeet Kumar Chaurasia; Rajendra Kumar Singh
Solid polymer electrolytes (SPEs) using polymer poly(ethylene oxide) (PEO), lithium salt bis(trifluoromethylsulfonyl)imide (LiTFSI) and ionic liquid (IL) trihexyltetradeylphosphonium bis(trifluoromethylsulfonyl)imide have been prepared. These prepared solid polymer electrolyte films have been characterised by using different experimental techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), complex impedance spectroscopy, Fourier transform infrared spectroscopy (FTIR), an electrochemical analyser etc. Changes in crystallinity, melting temperature (Tm), glass transition temperature (Tg), thermal stability and ionic transport behaviour of the prepared polymer electrolyte have been observed when the LiTFSI salt and different concentrations of IL were incorporated in the pristine polymer PEO. Ionic conductivity of the prepared solid polymer electrolyte (PEO + 20 wt% LiTFSI) has been found to increase with increasing IL concentration in polymer electrolytes up to 20 wt% IL. Total ionic transference number >0.99 and cationic transference number ∼0.37 with an electrochemical window of ∼3.34 V has been observed for the optimized solid polymer electrolyte (PEO + 20 wt% LiTFSI + 20 wt% IL). Temperature dependant ionic conductivity obeys Arrhenius type thermally activated behaviour. © 2016 The Royal Society of Chemistry.
Electrical conductivity studies on composite polymer electrolyte based on ionic liquid
(2010) Sujeet Kumar Chaurasia; Rajendra Kumar Singh
PEO: IL(1-ethyl-3-methylimidazolium Tosylate) and (PEO: IL) + xAl 2O3 polymer composite films have been obtained by (a) hot press and (b) solution cast techniques. The films prepared by hot press techniques give higher conductivity than their corresponding solution-casted samples. The PEO: IL polymer films conductivity has been found to increase with the amount of IL in PEO polymer matrix at a given temperature. The temperature dependence conductivity of PEO: IL films have been studied and discussed for the films prepared by two preparatory methods (a) hot press and (b) solution cast. The temperature dependence of conductivity exhibited an Arrhenius-type thermally activated behaviour. The ceramic filler Al2O3 concentration-dependent conductivity of PEO + IL (20 wt.%) film shows two conductivity maxima at 2 and 10 wt.%, respectively, which has been explained on the basis of double percolation threshold model. © 2010 Taylor & Francis.
Electrical, mechanical, structural, and thermal behaviors of polymeric gel electrolyte membranes of poly(vinylidene fluoride-co-hexafluoropropylene) with the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate plus lithium tetrafluoroborate
(John Wiley and Sons Inc, 2015) Shalu; Sujeet Kumar Chaurasia; Rajendra Kumar Singh; Suresh Chandra
Polymeric gel electrolyte membranes based on the polymer poly(vinylidene fluoride-co-hexafluoropropylene) [P(VdF-HFP)] with different weight percentages of the ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate plus 0.3M lithium tetrafluoroborate (LiBF4) salt were prepared and characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared (FTIR) spectroscopy, complex impedance spectroscopy, pulse echo techniques, and Vickers hardness (H) testing. After the incorporation of the IL plus the salt solution in the P(VdF-HFP) polymer, the melting temperature, glass-transition temperature (Tg), degree of crystallinity, thermal stability, elastic modulus (E), and hardness (H) gradually decreased with increasing content of the IL-salt solution as a result of complexation between the P(VdF-HFP) and IL. This was confirmed by FTIR spectroscopy. A part of the IL and LiBF4 were found to remain uncomplexed as well. The ionic conductivity (σ) of the polymeric gel membranes was found to increase with increasing concentration of the IL-salt solution. The temperature-dependent σs of these polymeric gel membranes followed an Arrhenius-type thermally activated behavior. © 2014 Wiley Periodicals, Inc.
Impact of ionic liquid incorporation on ionic transport and dielectric properties of PEO-lithium salt-based quasi-solid-state electrolytes: role of ion-pairing
(Springer, 2022) Sujeet Kumar Chaurasia; Manish Pratap Singh; Manoj K. Singh; Pramod Kumar; A.L. Saroj
The present paper reports the preparation and characterization of ionic liquid immobilized quasi-solid-state electrolytes (QS-SEs) “PEO-LiPF6-ionic liquid (IL)” with polymer PEO, dopant salt (LiPF6) and ionic liquid, BMIMPF6 having common anion (PF6-). AC impedance and Raman spectroscopic measurements showed that ionic conductivity (σ) of QS-SEs increases with IL-content and partly controlled by number of free mobile ions and their mobility/polymeric chain flexibility. Differential scanning calorimetry (DSC) results showed that melting temperature (Tm), glass transition temperature (Tg) and degree of crystallinity (Xc) of QS-SEs decreases with IL-content due to the plasticization effect of added IL(BMIMPF6). Furthermore, the composition-dependent conductivity data with IL-concentration is discussed in terms of increasing amorphicity (or deceasing crystallinity) as well as ion-polymer and ion-ion interactions. Ion dynamics of QS-SEs is examined by converting the impedance data into different ionic transport formalisms like ionic mobility (μ), charge carrier density (N) using the loss tangent (tan δ) spectra and showing that amount of added IL/salt are the responsible factors for controlling overall ion transport mechanism. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Structural and transport studies on polymeric membranes of PEO containing ionic liquid, EMIM-TY: Evidence of complexation
(2011) Sujeet Kumar Chaurasia; Rajendra Kumar Singh; Suresh Chandra
PEO:IL(1-ethyl-3-methylimidazolium tosylate, EMIM-TY) polymer electrolyte films are prepared by solvent free hot-pressing and characterized by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and Complex Impedance Spectroscopy. The FTIR/DSC/XRD studies confirm the complexation of the ionic liquid cation (EMIM+) with the ether oxygen, i.e. C-O-C group of PEO polymer backbone. The crystallinity of PEO+IL(EMIM-TY) electrolyte membranes has been found to decrease (plasticization effect) with ionic liquid EMIM-TY content in PEO up to a threshold weight ratio of ∼20 wt.% and then the crystallinity tends to increase. The room temperature ionic conductivity is found to depend both on the ionic liquid, EMIM-TY content and degree of crystallinity. The temperature dependence of the ionic conductivity of pure ionic liquid EMIM-TY, and the same ionic liquid in PEO matrix is also studied and discussed in this paper. © 2010 Elsevier B.V. All rights reserved.
The effect of ceramic nanofillers on conductivity and ion-transport behavior in potato starch-based solid bio-polymer electrolyte for advanced energy storage devices
(Springer Science and Business Media Deutschland GmbH, 2025) Km Jyoti Rai; Deepash Shekhar Saini; Prashant Shahi; Sujeet Kumar Chaurasia; Dipti Yadav; Neelam Srivastava; Rishabh Mishra; Manindra Kumar
The solution cast method was used to synthesize the nanocomposite solid polymer electrolytes, which were composed of potato starch (PS) as the host polymer, sodium iodide (NaI) as an ion source, and dispersed with Ce-substituted cobalt ferrite (CoFe1.95Ce0.05O4). The nanocomposite solid polymer electrolyte was characterized using a variety of techniques, including electrical impedance spectroscopy (EIS), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy and its deconvolution, X-ray diffraction (XRD), linear sweep voltammetry (LSV), cyclic voltammetry (CV), and galvanostatic charge–discharge (GCD). The maximum conductivity of 9.06 × 10−3 S/cm is attained for a system of 1.0 wt.% of Ce-substituted cobalt ferrite nanofillers. Inside the polymer matrix, the ion motion is triggered by the ceramic nanofillers. Therefore, the conductivity of the electrolyte was increased. The FTIR verified complexation behavior in the material. The deconvolution of FTIR spectra in the desired region yielded ion transport parameters, such as diffusion coefficient (D), mobility (µ), and carrier density (n). DSC thermograms indicate an endothermic process, and a broad melting peak at 60 °C is in the electrolyte system consisting of 50 wt.% NaI in potato starch due to the gelatinization of the starch granules, which is followed by another broad peak observed at 137 °C due to the dissociation of the material. TGA thermograms show multistage decomposition mechanisms with three processes. LSV and CV analyses indicate that the material is purely capacitive in nature and contains a broad electrochemical stability window, making it suitable for device applications. © The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature 2025.
Theoretical analysis of acoustic attenuation and nonlinearity in barium monochalcogenides in B2 phase
(2008) Rajendra Kumar Singh; Rishi Pal Singh; Manish Pratap Singh; Sujeet Kumar Chaurasia
Temperature dependence of ultrasonic attenuation due to phonon-phonon interaction and thermoelastic loss have been studied in (CsCl-type) barium monochalcogenides (BaX, X= S, Se, Te), in the temperature range 50-500 K; for longitudinal and shear modes of propagation along <100>, <110> and <111> directions. Second and third order elastic constants have been evaluated using electrostatic and Born repulsive potentials and taking interactions up to next nearest neighbours. Gruneisen parameters, nonlinearity constants, nonlinearity constants ratios and viscous drag due to screw and edge dislocations have also been evaluated for longitudinal and shear waves at 300 K. In the present investigation, it has been found that phonon-phonon interaction is the dominant cause for ultrasonic attenuation. The possible implications of the results have been discussed. © TÜBITAK.