Ionic Fluids Research Articles

Screening Lengths in Ionic Fluids.

The decay of correlations in ionic fluids is a classical problem in soft matter physics that underpins applications ranging from controlling colloidal self-assembly to batteries and supercapacitors. The conventional wisdom, based on analyzing a solvent-free electrolyte model, suggests that all correlation functions between species decay with a common decay length in the asymptotic far field limit. Nonetheless, a solvent is present in many electrolyte systems. We show using an analytical theory and molecular dynamics simulations that multiple decay lengths can coexist in the asymptotic limit as well as at intermediate distances once a hard sphere solvent is considered. Our analysis provides an explanation for the recently observed discontinuous change in the structural force across a thin film of ionic liquid-solvent mixtures as the composition is varied, as well as reframes recent debates in the literature about the screening length in concentrated electrolytes.

Graphene-based materials and structures for energy harvesting with fluids – A review

Graphene and graphene-based systems have recently been recognized as promising platforms for energy harvesting, microelectronic components and energy storage owing to their excellent electrical and thermal conductivity, outstanding mechanical properties, good chemical stability, area adaptability, among other significant properties. Integration of energy harvesting systems relying on the graphene/graphene-based materials in contact with fluids has been emphasized in recent years, as well as their potential impact on electric energy generation for a wide range of applications (e.g. innovative medical devices, advanced electronic systems and highly-efficient transduction systems for renewable energy). This review summarizes, for the first time, major breakthroughs carried out in the scope of energy harvesting exploiting graphene-based material systems (comprising graphene films, graphene grids, graphene membranes, 3D graphene composites and tribological structures) in contact with ionic and non-ionic fluids. Several transduction mechanisms for energy harvesting have been thoroughly analyzed. Energy outputs, materials and structures, substrates, types of fluid, manufacture methodologies, and experimental test methodologies are systematically highlighted in this review. Finally, future research directions and innovative applications of these harvesters are proposed.

Surface Modifications of Nanoparticles for Stability in Biological Fluids.

Due to the high surface: volume ratio and the extraordinary properties arising from the nanoscale (optical, electric, magnetic, etc.), nanoparticles (NPs) are excellent candidates for multiple applications. In this context, nanoscience is opening a wide range of modern technologies in biological and biomedical fields, among others. However, one of the main drawbacks that still delays its fast evolution and effectiveness is related to the behavior of nanomaterials in the presence of biological fluids. Unfortunately, biological fluids are characterized by high ionic strengths which usually induce NP aggregation. Besides this problem, the high content in biomacromolecules—such as lipids, sugars, nucleic acids and, especially, proteins—also affects NP stability and its viability for some applications due to, for example, the formation of the protein corona around the NPs. Here, we will review the most common strategies to achieve stable NPs dispersions in high ionic strength fluids and, also, antifouling strategies to avoid the protein adsorption.

Electrolytic Deposition of Hard Chromium Coatings from Electrolyte Based on Deep Eutectic Solvent

Deposition of chromium coatings from an electrolyte based on a deep eutectic solvent (new type of ionic fluids) was studied. The electrolyte used to deposit the coatings contained choline chloride, chromium(III) chloride, and addition of water. It was found that introduction of a certain amount of water makes it possible to raise the electrical conductivity and reduce the viscosity of the electrolyte to values acceptable for its practical application. The manner in which the electrolysis conditions affect the current efficiency for chromium deposition was determined. It was shown that uniform hard chromium coatings with good adhesion to the substrate can be deposited.

Developing Electrolyte Perturbed-Chain Statistical Associating Fluid Theory Density Functional Theory for CO2 Separation by Confined Ionic Liquids

The electrolyte perturbed-chain statistical associating fluid theory (ePC-SAFT) classical density functional theory (DFT) was developed to describe the behavior of pure ionic liquid (IL) and CO2/IL mixture confined in nanopores, in which a new ionic functional based on the ionic term from ePC-SAFT was proposed for electrostatic free-energy contribution. The developed model was verified by comparing the model prediction with molecular simulation results for ionic fluids, and the agreement shows that the model is reliable in representing the confined behavior of ionic fluids. The developed model was further used to study the behavior of pure IL and CO2/IL mixture in silica nanopores where the IL ions and CO2 were modeled as chains that consisted of spherical segments with the parameters taken from the bulk ePC-SAFT. The results reveal that the nanoconfinement can lead to an increased CO2 solubility, and the solubility increases with increasing pressure. The averaged density of pure IL and solubility of CO2 are strongly dependent on pore sizes and geometries. In addition, the choice of IL ions is very important for the CO2 solubility. Overall, the modeling results for silica-confined systems are consistent with available molecular simulation and experimental results.

Ionic fluids with association in dipoles and quadrupoles

The Debye–Hückel theory for an electrolyte solution is considered beyond dipole formation by including neutral clusters with four particles, through association between two positive and two negative ions. The Helmholtz free energy for the interaction between clusters and the ionic solution is evaluated according to Debye–Hückel theory. A simple association constant for the quadrupole complex is used, considering the electrostatic interaction between the ions in a fixed configuration. Hard-core contributions with Carnahan–Starling and free-volume theories are also included. The complete free energy shows phase separation, with a critical point in the region of numerical simulations.

Erratum to: “Fractionation of Wood with Binary Solvent 1-Butyl- 3-methylimidazolium Acetate + Dimethyl Sulfoxide”

In title section and ACKNOWLEDGMENTS Arktika Center of Collective Use of Scientific Equipment should be replaced by Core Facility Center “Arktika.” In abstract, line 7, and on page 666, line 24, exclusion should be replaced by size exclusion. On all pages of the paper, ionic fluid and IF should be replaced by ionic liquid and IL, respectively. On page 664, left column, last line, Kumlet–Taft should be replaced by Kamlet–Taft. On page 665, left column, line 34, frustrated total internal reflection should be replaced by attenuated total reflection. On page 665, left column, lines 35, 36, 40, FTIR should be replaced by ATR. On page 667, left column, line 25, [BMIn]Ac‒DMSO should be replaced by [BMIm]Ac‒DMSO.

High-ionic-strength pre-concentration via ion concentration polarization for blood-based biofluids

Ion concentration polarization (ICP) preconcentration is a pretreatment method that is actively utilized in the analysis of low-abundance biomolecules. In biofluids (e.g. urine, sweat, blood, serum, plasma, saliva, etc.), low-concentrated target analytes presented among large number of background molecules under a high ionic concentration, there still exist several hurdles in the utilization of ICP preconcentration in the such high ionic fluids. This is especially true in the case of blood-based biofluids, such as plasma and serum, wherein on account of the abundance biomolecules as well as high ionic buffer concentration makes the ICP preconcentration process difficult to realize. In this study, we have demonstrated the realization of ICP preconcentration of blood-based biofluids (serum) using a paper-based preconcentrator. We acquired preconcentration factors (PF) for 25.5, 127.5 and 255 mM of human serum were 40, 10, and 5.5 within 20 min. The squared fluorescence intensity is also found to be inversely proportional to ionic concentration, showing that the PF are strongly correlated to the Debye length of the buffer solution. Using the paper-based preconcentrator, we were able to acquire effective preconcentration factor (PFeff) of 5.17, 4.88, 4.58, and 4.23 for the 1X, 0.75X, 0.5X, and 0.1X diluted solutions, demonstrating approximately 5 times increase in PFeff for all prepared human serum samples.

Thermoelectricity in Heterogeneous Nanofluidic Channels.

Ionic fluids are essential to energy conversion, water desalination, drug delivery, and lab-on-a-chip devices. Ionic transport in nanoscale confinements and complex physical fields still remain elusive. Here, a nanofluidic system is developed using nanochannels of heterogeneous surface properties to investigate transport properties of ions under different temperatures. Steady ionic currents are observed under symmetric temperature gradients, which is equivalent to generating electricity using waste heat (e.g., electronic chips and solar panels). The currents increase linearly with temperature gradient and nonlinearly with channel size. Contributions to ion motion from temperatures and channel properties are evaluated for this phenomenon. The findings provide insights into the study of confined ionic fluids in multiphysical fields, and suggest applications in thermal energy conversion, temperature sensors, and chip-level thermal management.

New Insights into Computational Fluid Dynamic (CFD) Modeling of Concentration Overpotential

Salinity gradient power (SGP) is a promising source of sustainable energy production involving technologies such as pressure retarded osmosis (PRO), reverse electrodialysis (RED) and capacitive mixing (CAPMIX). Coupling these technologies to their counterparts used for desalination, salinity gradient batteries can in principle be developed [1], as recently demonstrated for RED/ED [2]. Electrode and membrane processes typically involve an accumulation or depletion of specific ions compared the bulk solution, resulting in so called concentration polarization. Concentration polarization is a considerable challenge in RED/ED, effectively reducing the driving force across the membrane, hence reducing the performance of the process [3]. In addition to concentration polarization, the presence of concentration gradients will result in both Ohmic and non-Ohmic contributions to the electrical potential [3], further influencing the characteristics of the system. Different strategies have been proposed in order to mitigate the influence of concentration gradients, specifically increasing the flow velocity and introducing flow promoters – typically by optimizing the spacer geometry [3, 4] – in order to alter momentum and concentration boundary layers. The interaction between ionic species and fluid flow can be achieved by solving the coupled Navier-Stokes (NS) and Nernst-Planck (NP) equations [5,6], allowing for simultaneous prediction of flow and pressure fields, concentration and electrical potential, all of which of interest for the overall performance of the system. The current work describes a simulation framework for simulation of the NS-NP system based on the open source CFD platform OpenFOAM [7], aiming to predict the influence of flow conditions and geometry on concentration and electrical potential. Figure 1 (left) shows constant, linear and parabolic concentration profiles, corresponding to the extreme conditions of plug and Poiseuille flow in a flat channel, with the corresponding results for electrical potential in Figure 1 (right), clearly demonstrating the strong coupling between the two. The suggested framework is applied to spacer filled channels aiming to describe pros and cons of different configurations such as height and pitch of spacers. The presented approach sheds light on future concentration polarization modeling, providing better descriptions of the mass transfer and electric potential and highlighting the role of spacer-filled channel in membrane based processes.

Fractionation of Wood with Binary Solvent 1-Butyl-3-methylimidazolium Acetate + Dimethyl Sulfoxide

It is suggested to use a binary solvent, 1-butyl-3-methylimidazolium acetate + dimethyl sulfoxide, for full dissolution of wood, followed by its separation into the polysaccharide and lignin components. The optimal conditions of the wood treatment process were determined (temperature 120°C, processing duration 6 h). A scheme is suggested for double-stage fractionation of the lignin‒cellulose biomass. The scheme is based on the successive precipitation of the dissolved components with acetone and water. The isolated polysaccharide and lignin fractions constituting, combined, 70% of the initial mass of wood were characterized by IR and NMR spectroscopy, exclusion chromatography, electron microscopy, and functional analysis. It was found that the polysaccharide fraction has the form of amorphous cellulose (2% degree of crystallinity) containing about 15% lignin. The isolated lignin contains no significant admixtures of polysaccharides, has a mass-average molecular mass of about 5 kDa, and is close to organosolvent lignins. It was found that the lignin fraction contains up to 35% residual ionic fluid. A suggestion is made about the possibility of chemical binding between lignin and butyl-3-methylimidazolium cations.

Vapor-liquid phase behavior of a size-asymmetric model of ionic fluids confined in a disordered matrix: The collective-variables-based approach.

We develop a theory based on the method of collective variables to study the vapor-liquid equilibrium of asymmetric ionic fluids confined in a disordered porous matrix. The approach allows us to formulate the perturbation theory using an extension of the scaled particle theory for a description of a reference system presented as a two-component hard-sphere fluid confined in a hard-sphere matrix. Treating an ionic fluid as a size- and charge-asymmetric primitive model (PM) we derive an explicit expression for the relevant chemical potential of a confined ionic system which takes into account the third-order correlations between ions. Using this expression, the phase diagrams for a size-asymmetric PM are calculated for different matrix porosities as well as for different sizes of matrix and fluid particles. It is observed that general trends of the coexistence curves with the matrix porosity are similar to those of simple fluids under disordered confinement, i.e., the coexistence region gets narrower with a decrease of porosity and, simultaneously, the reduced critical temperature T_{c}^{*} and the critical density ρ_{i,c}^{*} become lower. At the same time, our results suggest that an increase in size asymmetry of oppositely charged ions considerably affects the vapor-liquid diagrams leading to a faster decrease of T_{c}^{*} and ρ_{i,c}^{*} and even to a disappearance of the phase transition, especially for the case of small matrix particles.

A study on the variation of zeta potential with mineral composition of rocks and types of electrolyte

Streaming potential in rocks is the electrical potential developing when an ionic fluid flows through the pores of rocks. The zeta potential is a key parameter of streaming potential and it depends on many parameters such as the mineral composition of rocks, fluid properties, temperature etc. Therefore, the zeta potential is different for various rocks and liquids. In this work, streaming potential measurements are performed for five rock samples saturated with six different monovalent electrolytes. From streaming potential coefficients, the zeta potential is deduced. The experimental results are then explained by a theoretical model. From the model, the surface site density for different rocks and the binding constant for different cations are found and they are in good agreement with those reported in literature. The result also shows that (1) the surface site density of Bentheim sandstone mostly composed of silica is the largest of five rock samples; (2) the binding constant is almost the same for a given cation but it increases in the order KMe(Na+) < KMe(K+) < KMe(Cs+) for a given rock.References Corwin R. F., Hoovert D.B., 1979. The self-potential method in geothermal exploration. Geophysics 44, 226-245. Dove P.M., Rimstidt J.D., 1994. Silica-Water Interactions. Reviews in Mineralogy and Geochemistry 29, 259-308. Glover P.W.J., Walker E., Jackson M., 2012. Streaming-potential coefficient of reservoir rock: A theoretical model. Geophysics, 77, D17-D43. Ishido T. and Mizutani H., 1981. Experimental and theoretical basis of electrokinetic phenomena in rock-water systems and its applications to geophysics. Journal of Geophysical Research, 86, 1763-1775. Jackson M., Butler A., Vinogradov J., 2012. Measurements of spontaneous potential in chalk with application to aquifer characterization in the southern UK: Quarterly Journal of Engineering Geology & Hydrogeology, 45, 457-471. Jouniaux L. and T. Ishido, 2012. International Journal of Geophysics. Article ID 286107, 16p. Doi:10.1155/2012/286107. Kim S.S., Kim H.S., Kim S.G., Kim W.S., 2004. Effect of electrolyte additives on sol-precipitated nano silica particles. Ceramics International 30, 171-175. Kirby B.J. and Hasselbrink E.F., 2004. Zeta potential of microfluidic substrates: 1. Theory, experimental techniques, and effects on separations. Electrophoresis, 25, 187-202. Kosmulski M., and Dahlsten D., 2006. High ionic strength electrokinetics of clay minerals. Colloids and Surfaces, A: Physicocemical and Engineering Aspects, 291, 212-218. Lide D.R., 2009, Handbook of chemistry and physics, 90th edition: CRC Press. Luong Duy Thanh, 2014. Electrokinetics in porous media, Ph.D. Thesis, University of Amsterdam, the Netherlands. Luong Duy Thanh and Sprik R., 2016a. Zeta potential in porous rocks in contact with monovalent and divalent electrolyte aqueous solutions, Geophysics, 81, D303-D314. Luong Duy Thanh and Sprik R., 2016b. Permeability dependence of streaming potential coefficient in porous media. Geophysical Prospecting, 64, 714-725. Luong Duy Thanh and Sprik R., 2016c. Laboratory Measurement of Microstructure Parameters of Porous Rocks. VNU Journal of Science: Mathematics-Physics 32, 22-33. Mizutani H., Ishido T., Yokokura T., Ohnishi S., 1976. Electrokinetic phenomena associated with earthquakes. Geophysical Research Letters, 3, 365-368. Ogilvy A.A., Ayed M.A., Bogoslovsky V.A., 1969. Geophysical studies of water leakage from reservoirs. Geophysical Prospecting, 17, 36-62. Onsager L., 1931. Reciprocal relations in irreversible processes. I. Physical Review, 37, 405-426. Revil A. and Glover P.W.J., 1997. Theory of ionic-surface electrical conduction in porous media. Physical Review B, 55, 1757-1773. Scales P.J., 1990. Electrokinetics of the muscovite mica-aqueous solution interface. Langmuir, 6, 582-589. Behrens S.H. and Grier D.G., 2001. The charge of glass and silica surfaces. The Journal of Chemical Physics, 115, 6716-6721. Stern O., 1924. Zurtheorieder electrolytischendoppelschist. Z. Elektrochem, 30, 508-516. Tchistiakov A.A., 2000. Physico-chemical aspects of clay migration and injectivity decrease of geothermal clastic reservoirs: Proceedings World Geothermal Congress, 3087-3095. Wurmstich B., Morgan F.D., 1994. Modeling of streaming potential responses caused by oil well pumping. Geophysics, 59, 46-56.

An objective measure for the assessment and management of fluid shifts in acute major burns

BackgroundMajor burns are life threatening. Fluid resuscitation is required for survival to maintain intravascular volumes and prevent hypovolemic shock. Bioimpedance spectroscopy (BIS) has been recognised as a potential method of monitoring fluid shifts after burn and in other disease states. The aims of this study were to examine the reliability of BIS across different dressing conditions and electrode positions, establish the influence of Acticoat™ on BIS variable measures and determine the validity of whole-body BIS to assess net fluid shift in the presence of moderate to major burns.MethodsAn observational longitudinal cohort study was conducted from December 2014 to February 2016. Patients with over 15% total body surface area (TBSA) burns and injury less than 48 h were enrolled in the study. BIS triplicate measures were collected in an open wound and with an ActicoatTM dressing (at 5 half hour intervals). Standard and alternate electrode placements were utilised for the reliability analysis and standard placement only for determining the validity of BIS in moderate to major burns. The ImpediMde SFB7 was used to collect whole-body and segmental BIS measures. Stata statistical software, release 14 was utilised to analyse all results. Descriptive analyses were performed and were reported using the means and standard deviations (SD).ResultsBIS-repeated measures established BIS raw resistance (R), and predicted volume variables were reliable in any condition (intra-class correlation coefficient (ICC) 0.996–0.999, 95% confidence intervals (CI) 0.996–0.999) without a systematic difference. Acticoat™ dressings significantly influenced all BIS-predicted volumes (p ≤ 0.01) as determined by multilevel mixed effects (MLME) linear regression analysis. Validity of BIS was demonstrated by resistance variables significantly decreasing with increasing net ionic fluid shift and increased TBSA (severity of injury) and calculated fluid volumes increasing with increasing net fluid shift and TBSA. BIS resistance also decreased with time as oedema reduced. For clinical use, a calculator was developed to adjust BIS variables when an Acticoat™ dressing is in situ, thus facilitating BIS variable change estimates in real time, with dressings intact.ConclusionBIS may be used clinically to monitor fluid volume change in major acute burns.

Verification of the effect of the axon fluid as a highly dielectric medium in the high-speed conduction of action potentials using a novel axon equivalent circuit.

Both sensory neurons and motor neurons transfer signals rapidly through long pathways. Such signals propagate as action potentials through neurons. In myelinated neurons, high conduction velocities of 120 m/s have been reported, even for axons of just 20 μm in diameter. Such a high conduction velocity is enabled by the characteristic morphology of a myelinated axon: repeated regions encased by long uniform myelin sheaths alternating with extremely short exposed regions of the axon called nodes of Ranvier, which generate extremely sharp action potentials. Although the need for the action potential to cross many nodes increases the relay time, it is still able to propagate rapidly. This phenomenon motivated us to derive a new mechanism of the action potential propagation. First, the dielectric effect of the axonal fluid was considered, and it was investigated whether the combination of the characteristic axonal morphology and the dielectric constant of the axonal fluid contributes significantly to the realization of high conduction velocities even with the inclusion of a large loss in the relay time. To this end, we propose a new axon equivalent circuit that incorporates the effect of the dielectric characteristics of the axonal fluid. It was confirmed that a realistically high conduction velocity could be calculated using the proposed circuit and that the dielectric constant calculated using the proposed circuit was in agreement with that of an ionic fluid similar to axonal fluid. Moreover, the contribution of the combination of the axonal morphology and axonal fluid to the conduction velocity was confirmed.

Vapour-liquid critical parameters of a 2:1 primitive model of ionic fluids confined in disordered porous media

We study the vapour-liquid critical parameters of an ionic fluid confined in a disordered porous medium by using the theory which combines the collective variables approach with an extension of the scaled particle theory. The ionic fluid is described as a two-component charge- and size-asymmetric primitive model, and a porous medium is modelled as a disordered matrix formed by hard-spheres obstacles. In the particular case of the fixed valencies 2:1, the coexistence curves and the corresponding critical parameters are calculated for different matrix porosities as well as for different diameters of matrix and fluid particles. The obtained results show that the general trends of the reduced critical temperature and the reduced critical density with the microscopic characteristics are similar to the trends obtained in the monovalent case. At the same time, it is noticed that an ion charge asymmetry significantly weakens the effect of the matrix presence.

Adsorption of mixtures of the Yukawa-ions near a hard wall: A density functional study based on the third-order Ornstein-Zernike relation

We examine the adsorption of the primitive-model “ionic” mixtures modeled in terms of the screened Debye potentials on a hard structureless wall. It is well-known that the screened Debye potentials are of the Yukawa form. They could approach the Coulomb potentials when the screen parameter λ vanishes. Thus the study of the mixtures of repulsive and attractive Yukawa molecules can mimic the ionic fluid behavior at small λ. One of the advantages of using this Yukawa potential is that it avoids the long-range interactions and mitigates the complications inherent in the Coulomb potential.We have previously developed a third-order Ornstein-Zernike relation (OZ3) and have adapted it to the adsorption of many types of fluids on hard walls. Specifically, a new generation of closures was developed for use in the Euler-Lagrange equations of the density functional theory (DFT) for determining the non-uniform densities of various fluid types: such as the Lennard-Jones fluid, as well as the regular Yukawa fluids (with finite λ values) on an inhomogeneous substrate. In this work, we examine the applicability of the OZ3-inspired bridge functions to the adsorption of the “small-λ” Yukawa fluids. The mixtures of these Yukawa fluids are, for simplicity, called the Yukawa ions, in contrast to the Coulomb ions. The results shall mimic the electrical double layers in electrochemistry.The Euler-Lagrange equations for the binary mixtures are solved with new OZ3 closures. Two types of closures are investigated: one derived from the Jackson-Feenberg approximation, and the other derived from the linear cavity approximation. The results are compared with the Monte-Carlo results on primitive-model symmetric ions and asymmetric ions on a neutral hard structureless wall. Satisfactory agreements are obtained. It is noted that the contact value theorems (i.e. the hard-wall sum rules) play an instrumental role in obtaining the accurate results.

Synthesis of Mn2O3 nanoparticles using choline chloride-ethylene glycol deep eutectic solvent: A green solvent

ABSTRACTMn2O3 particles of nano scale were fabricated using deep eutectic solvent of choline chloride-ethylene glycol. Deep Eutectic Solvents (DES) is a new family of ionic fluids. Mn2O3 was fabricated by varying the amount of water in DES. With variation in amount of water, size and shape of particles also varied. Mn2O3 prepared in absence of water is of orthorhombic crystal system and those prepared in presence of water are of tetrahedral crystal system. Photocatalytic property of these Mn2O3 particles was also demonstrated using safranin-O dye. Rate constant calculated by plotting log A vs Time follow: k0.5 ml water > k0.0 ml water > k1 ml water.

Microscopic theory of simple fluids

Analyzing the basic details of a simple fluid, we developed its microscopic theory and discovered that (i) every fluid is a homogeneous mixture of two fluids, SUB1 and SUB2, respectively, composed of non-interacting quasi-particles (QP1) and interacting QP2, and (ii) its behavior is controlled by Pin(q)+Pin(K)=Pex+Pcoh as its equation of state (EOS) where Pin(q) and Pin(K) are two components of its internal pressure, while Pex and Pcoh, respectively, represent external and cohesive pressures. It further reveals the temperature (T) and pressure (P) dependence of compressibility factor (Z) of the fluid and its universal component Z(T)Vc=1+B2(T)/Vc (with B2(T) being its second virial coefficient), the reasons for the coexistence of liquid and vapor and the relation between their particle number densities ρl and ρg. It explains criticality and critical condensation/evaporation and, for the first time, unravels the microscopic origin of important empirical rules such as Trouton rule and Guldberg rule (discovered about 130years back) and several principles of corresponding states (PCS) discovered by Guggenheim. Our results have very good agreement with experiments. We hope our theory may emerge as an important means to (i) explain different properties of simple fluids, (ii) provide necessary foundation to develop similar theories of polar, strongly polar, ionic and complex fluids, and (iii) render useful direction for better understanding of widely different physico-chemical, bio-chemical and bio-physical processes and related aspects.

Influence of anion structure on thermal, mechanical, dielectric and electrochemical properties of ZrO2 nanoparticle-pyrrolidinium ionic liquid hybrid electrolytes for the application in energy storage devices

Influence of the two different anion structures viz. bis(fluorosulfonyl)imide (FSI−) and bis(trifluoromethanesulfonyl) imide (TFSI−), on the thermophysical, dielectric and electrochemical properties of ZrO2-nanoparticle tethered pyrrolidinium based nanoscale hybrid ionic fluids (NHIFs) was investigated. Thermal and mechanical properties of NHIFs were found to depend strongly upon the structure of anions and TFSI− comprising NHIF showed better thermal and mechanical stability then its FSI− analogue. Temperature dependent electrical conductivity, dielectric and electrochemical properties of different NHIFs were studied. FSI-NHIF displayed higher ionic conductivity, associated with faster structural relaxation dynamics. At all the measured temperature, FSI-NHIF displayed superior electrochemical cycling performance than its TFSI-equivalent. While, electrochemical cell with TFSI-NHIF showed 81% capacitance retentivity after 5000 charge/discharge cycles, FSI-NHIF cell was found to retain >90% of its initial specific capacitance value after the same. Results obtained from the study optimize the applicability of pyrrolidinium based hybrid ionic fluids as electrolytes in secondary energy storage devices.