Dc Ionic Conductivity Research Articles

Crystallization kinetics and structural studies of Li1.25Al0.5Ge1.5P2.75Mo0.25O12 (LAGPM) glass/glass-ceramics based solid state electrolyte

The crystallization kinetics and structural behaviour of Li1.25Al0.5Ge1.5P2.75Mo0.25O12 (LAGPM) glass/glass-ceramics system have been investigated. Glass was prepared by melting the calcined initial charges at 1450 °C using conventional quenching technique. From model free crystallization kinetics, the value of activation energy obtained was 165 kJ mol−1. The nature of nucleation and the dimension of growth of the NASICON crystal were estimated from the kinetics parameters. This glass was converted to glass-ceramics using suitable heat schedule as per DTA data. X-ray diffraction analysis confirmed the formation of desired NASICON phase along with AlPO4 as minor phase. Raman spectroscopy and EXAFS studies showed that molybdenum ions moved to the desired tetrahedral sites in glass-ceramic. The dimension of the crystal growth was clearly seen in SEM image of LAGPM glass-ceramics sample. Impedance spectroscopy was carried out to evaluate the dc ionic conductivity (σdc) of LAGPM glass-ceramics based solid electrolyte. The value of σdc evaluated from the Nyquist plot was found as ∼4.64 × 10−4 S.cm−1 at room temperature.

Nano alumina effect on ionic conductivity of (X)KNO3 – (1-X)Ba(NO3)2

In this research, the dc ionic conductivity of (X)KNO3–(1-X) Ba(NO3)2 systems has been investigated by varying the particle size of diffused nano alumina. Crystals of Ba(NO3)2 and KNO3 were synthesized by slow evaporation method. DSC,DTA and XRD analysis of the diffused systems indicate no new phase has been evolved after the addition of alumina. An increase in ionic conductivity has been observed upto a threshold mole percent in the diffused system with various particle size of Al2O3. Around 2 3 order magnitude difference in conductivity value is also recorded in the diffused samples as compared to unmodified system. The enhancement of ionic conductivity has also been explained on the basis of generation of vacancies and development of space charge region in the system. we have aimed at enhancing the conductivity of this host by studying the influence of γ-Al2O3 with different particle sizes viz. 1 µm, 0.3 µm, 0.06 µm. An attempt has been made to identify the conductivity enhancement mechanism operating in this system.

Understanding Structure-Property Relationships in Deep Eutectic Solvents (DESs)

Deep eutectic solvents (DESs) are an emerging class of highly tunable solvents with unique properties such as high solvent strength, wide electrochemical and thermal stability windows, nonflammability, and biodegradability/nontoxicity. These have given them potential as in many areas, including electrochemical technology applications like redox flow batteries and solar cells. However, they are held back by their relatively high viscosities and low conductivities. For this reason, it would be useful to understand how to improve these materials for target applications based off their molecular identity. Here, we use a variety of experimental techniques to study a series of choline-based DESs which are systematically varied by functional group and its position to examine the changes in local structure and dynamics and that effect on macroscopic properties. Generally, we observe that slight structural changes result in significant changes in the eutectic composition, viscosity, and dc ionic conductivity.

Ion Dynamics and Charge Transport in Imidazolium Chloroaluminate Ionic Liquids

Ion dynamics and charge transport in a homologous series of imidazolium chloroaluminate ionic liquids are investigated by broadband dielectric spectroscopy, rheology, viscometry, and differential scanning calorimetry. The interplay of anion speciation and alkyl chain length on local and mesoscale dynamics and the corresponding influence on the dc ionic conductivities, zero-shear viscosities, and static dielectric permittivities is investigated. These results are presented within a broader framework of current understanding of dynamics and transport properties of aprotic ionic liquids.

Anion Equilibria and Stability of Quaternary Phosphonium Chloroaluminate Ionic Liquids

The anion equilibria and thermal stability in a series of quaternary trialkyloctylphosphonium chloroaluminate ionic liquids are investigated qualitatively by Raman spectroscopy, broadband dielectric spectroscopy, and nuclear magnetic resonance spectroscopy. Results indicate that Lewis acidic chloroaluminate ionic liquids based upon the phosphonium cation are less stable than those based upon other molecular cations. A slow time-dependent drop in room-temperature dc ionic conductivity as well as a step drop at elevated temperatures is tentatively attributed to a reaction involving the Lewis acidic Al2Cl7 - anion and the phosphonium cations. This reaction results in significant changes in the 1H, 13C, and 31P NMR spectra, but only minor changes in the Raman spectra. Furthermore, extended time at elevated temperatures results in a significant quantity of neutral aluminum chloride sublimating from the liquid. These results demonstrate an unusual reactive instability of phosphonium-based Lewis acidic chloroaluminate ILs.

DC Ionic Conductivity in KTP and Its Isomorphs: Properties, Methods for Suppression, and Its Connection to Gray Tracking

We study the DC conductivity in potassium titanyl phosphate (KTiOPO4, KTP) and its isomorphs KTiOAsO4 (KTA) and Rb1%K99%TiOPO4 (RKTP) and introduce a method by which to reduce the overall ionic conductivity in KTP by a potassium nitrate treatment. Furthermore, we create so-called gray tracking in KTP and investigate the ionic conductivity in theses areas. A local unintended reduction of the ionic conductivity is observed in the gray-tracked regions, which also induce additional optical absorption in the material. We show that a thermal treatment in an oxygen-rich atmosphere removes the gray tracking and brings the ionic conductivity as well as the optical transmission back to the original level. These studies can help to choose the best material and treatment for specific applications.

Facile fabrication of NiO doped PVDF-co-HFP/Mg(ClO4)2polymer composite membrane as a counter electrode in low-cost dye-sensitized solar cells

ABSTRACT Poly(vinylidene co-hexafluoropropylene) (PVDF-HFP) has gained considerable attention as an alternative to the commercial separators in energy devices. NiO nanofiller-based solid polymer composite electrolytic thin membranes (PVDF-co-HFP:Mg(ClO4)2:NiO) were prepared using solid PVDF-co-HFP copolymer and Mg(ClO4)2via the solution-casting method. The obtained thin membranes were structurally characterized by FTIR, the porosity of the membrane was analyzed by scanning electron microscope (SEM) and an optimum SEM micrograph of 20.0 μm magnification was taken to analyze the exact porous diameter distribution frequency. XRD analysis was used to confirm the physical state of the PVDF-co-HFP membrane and the composite membrane of (PVDF-co-HFP:Mg(ClO4)2:NiO). Structural studies related to XRD peaks were broadened at an optimized Mg(ClO4)2 salt concentration, confirming the presence of maximum amorphous content in the PVDF-co-HFP:Mg(ClO4)2 composite. Using the Nyquist plot, the ohmic resistance (R Ω ), polarization resistance (R P ), and Warburg impedance (W) were determined to be at their lowest values for an optimum concentration of NiO nanofiller in the PVDF-co-HFP:Mg(ClO4)2:NiO composite. The homogeneous dispersion of the nanofiller significantly improved the contact between electrode and electrolyte interfaces, resulting in high ionic conductivity. The DC and AC ionic conductivities of the pure PVDF-co-HFP and composite membrane of (PVDF-co-HFP:Mg(ClO4)2:NiO) was studied by electrochemical impedance spectroscopy (EIS), and the optimum ionic conductivity was estimated as . A spin-coating technique was employed to prepare dye-sensitized solar cells (DSSC). The fill factor and efficiency (= 11.12532 were estimated from the J-V graph.

Governing mechanism of ion transport in lithium-iron-phosphate glasses

We show a fundamental relationship between network structural attributes and ionic transport of lithium iron phosphate glasses xLi2O–2Fe2O3–3 P2O5 (xLFPO; x = 0.375, 0.75, 1.5, 3.0) used for a cathode in lithium-ion batteries. The glass samples have been synthesized using a solid-state reaction method. We have investigated the electrical characteristics of the glass by combinational measurements of electrical impedance in the frequency 100 Hz – 30 MHz and temperature from ambient to 240 °C, differential thermal analysis, X-ray diffraction pattern, and Raman spectroscopy. The ionic hopping and relaxation processes in xLFPO glasses are analyzed by using Cole-Cole, power law, and modulus representations. We reveal that the exponential increase in dc conductivity with increasing Li2O in xLFPO glasses is caused by the combination of an increase in non-bridging oxygen sites and a change in the bonding forces of iron valence surrounding the iron phosphate clusters inside the network. The power law conductivity, which is driven by the fractional Rayleigh equation, exhibits that the rate of increase in dc ionic conductivity is the same as the rate of increasing numbers of the ionic charge carriers. Raman spectra show that the increase of depolymerization of the iron phosphate network with the addition of Li2O content is due to the conversion of Q2 to Q1 and Q0 species.

Structural and electrochemical studies of proton conducting biopolymer blend electrolytes based on MC:Dextran for EDLC device application with high energy density

This study shows preparation and characterization of solid biopolymer electrolyte based on glycerolized methylcellulose (MC): dextran-doped with ammonium thiocyanate (NH4SCN). The nature of electrolyte composition in terms of interaction is characterized using Fourier transform infrared (FTIR) technique. Lowering and shifting in the intensity of the bands are observed with increasing the quantity of glycerol as a plasticizer, confirming complexation between electrolyte components. Ion transport parameters are determined using both of the methods of EIS and FTIR where the parameters are found to be increased with glycerol concentration. The transport number measurement indicates that ions are the primary charge carrier in the conduction mechanism where tion is found to be 0.961. The maximum DC ionic conductivity value is achieved that found to be 1.63 × 10−3 S cm−1. The ESR values are ranged from 300 to 580 Ω throughout 450 cycles. The technique of linear sweep voltammetry (LSV) shows the electrochemical stability window of 2 V for the conducting samples. The response of cyclic voltammetry (CV) shows an almost rectangular shape without Faradaic peaks. A galvanostatic charge–discharge investigation has shown the initial specific capacitance, energy density, and power density are 133 F g−1, 18.3 Wh Kg−1, and 680 W Kg−1, respectively.

Lithium-salt-based deep eutectic solvents: Importance of glass formation and rotation-translation coupling for the ionic charge transport.

Lithium-salt-based deep eutectic solvents, where the only cation is Li+, are promising candidates as electrolytes in electrochemical energy-storage devices, such as batteries. We have performed broadband dielectric spectroscopy on three such systems, covering a broad temperature and dynamic range that extends from the low-viscosity liquid around room temperature down to the glassy state approaching the glass-transition temperature. We detect a relaxational process that can be ascribed to dipolar reorientational dynamics and exhibits the clear signatures of glassy freezing. We find that the temperature dependence of the ionic dc conductivity and its room-temperature value also are governed by the glassy dynamics of these systems, depending, e.g., on the glass-transition temperature and fragility. Compared to the previously investigated corresponding systems, containing choline chloride instead of a lithium salt, both the reorientational and ionic dynamics are significantly reduced due to variations in the glass-transition temperature and the higher ionic potential of the lithium ions. These lithium-based deep eutectic solvents partly exhibit significant decoupling of the dipolar reorientational and the ionic translational dynamics and approximately follow a fractional Debye-Stokes-Einstein relation, leading to an enhancement of the dc conductivity, especially at low temperatures. The presented results clearly reveal the importance of decoupling effects and of the typical glass-forming properties of these systems for the technically relevant room-temperature conductivity.

Understanding the sodium-ion dynamics in NASICON (Na3Al2P3O12) glass containing NaF: Scaling of electrical conductivity spectra

Quest for high ion-conducting solid electrolyte materials for sodium-ion batteries has been tremendously increasing. Glass materials are a potential solid electrolyte for high-energy Na-ion batteries. Nevertheless, the effective research on glass materials for their applications in Na-ion batteries is dawdling due to its low ionic DC-conductivity and poor understanding of the dynamics of mobile cations. Herein, we have attempted to address the effect of substitution of NaF for Al2O3 on the conductivity of Na3Al2P3O12(NAP) glass (mol%: 37.5P2O5–25.0Al2O3–37.5 Na2O). Raman spectra reveal that the increase in the substituent NaF concentration significantly affects the coordination of Al3+ and the distribution of sodium cations in the network structure of NAP glass. Impedance spectra reveal that the change in conductivity of NAP glass with an increase in the NaF concentration is highly dependent on a specific temperature range. At a lower temperature range, (<150 °C), the conductivity increases initially with the increase in NaF concentration and it decreases with any further increase in the NaF concentration; whereas, at temperatures above 150 °C, the conductivity increases continuously with an increase in the NaF concentration. The frequency-dependent AC-conductivity has been analyzed using the time-temperature scaling principle (TTSP) based on Summerfield and Ghosh scaling procedures to probe the ion conduction mechanism. The NAP glass that contains low NaF concentrations (<7.5 mol%) obeys the AC-conductivity scaling, i.e., it satisfies the TTSP principle, with respect to temperature based on the Summerfield scaling procedure; this indicates that the sodium-ion dynamics are independent of the temperature. The scaled AC-conductivity curves for NAP glass containing high NaF concentrations (>10 mol%) have deviated from Summerfield scaling and further indicate that the fraction of sodium-ions responsible for the ionic conductivity is decreasing with an increase in the temperature. Scaling of AC-conductivity curves for all the glass samples using the Ghosh procedure suggests that the number density along with the hopping distance of sodium ions changes with increasing temperature. The Modified random network structural model has been further utilized to explain the variation in the NAP glass conductivity with an increase in the NaF concentrations. The outcome of this work will certainly aid in designing the chemical compositions of glasses for the development of solid electrolyte materials for their applications in Na-ion batteries.

Ion Dynamics and Charge Transport in Imidazolium Chloroaluminate Ionic Liquids

Imidazolium-based chloroaluminates were the first widely studied room-temperature ionic liquids. Now, following 25 years of intense study of ionic liquids with less reactive anions, researchers are beginning to rediscover chloroaluminates, and other halometallate ILs, because they possess potentially advantageous properties that hold significant promise for applications such as energy storage, electrodeposition, and chemical synthesis. The majority of work characterizing the imidazolium-based chloroaluminates was conducted more than 25 years ago and focused on physical property measurements across limited compositions and/or narrow temperature/frequency ranges. In this study, we employ broadband dielectric spectroscopy, rheology, and differential scanning calorimetry to investigate ion dynamics and charge transport in a series of 1-alkyl-3-methylimidazolium chloroaluminates over much broader frequency and temperature ranges than these prior studies. The influence of cation chemical structure on the time-scales of ion-hopping, structural relaxation, and interfacial polarization associated with mesoscale solvophobic aggregates will be compared with other classes of aprotic imidazolium ionic liquids to highlight important differences observed for chloroaluminates. Finally, the influence of the relaxation time-scales on transport properties including dc ionic conductivity, zero-shear viscosity, and static dielectric permittivity will be presented. These new, in-depth studies, are focused on developing underlying structure-property relationships that are critical to realizing the full potential of chloroaluminate ionic liquids as electrolyte systems.

A DFT-based model to the interpretation of DC conductivity in transition metals doped zinc phosphate glass

Ternary zinc–sodium–phosphate glasses doped with transition metal of the composition Na2MxZn1−xP2O7(x = 0, 1, 2 and 5 mol %) (where M = Ni, Cu and Co) were prepared by the traditional quenching method. The ac conductivity measurements at different temperatures for the prepared glasses have been investigated, and the activation energy for dc conduction has been determined in each transition metal doped sample. The results showed that the evolution of the activation energy of the conductivity depends on the nature of the dopant ions. A model based on formal density functional theory concept in which the electrical charge exchanged between the transition-metal cations and the surrounding material surface is proposed. The outcome is a “simplified” formula which allows us to explain the evolution of the ionic dc conductivity activation energy as a function of the doped ion in interaction with the cation and the surface.

Translational and reorientational dynamics in deep eutectic solvents.

We performed rheological measurements of the typical deep eutectic solvents (DESs) glyceline, ethaline, and reline in a very broad temperature and dynamic range, extending from the low-viscosity to the high-viscosity supercooled-liquid regime. We find that the mechanical compliance spectra can be well described by the random free-energy barrier hopping model, while the dielectric spectra on the same materials involve significant contributions arising from reorientational dynamics. The temperature-dependent viscosity and structural relaxation time, revealing non-Arrhenius behavior typical for glassy freezing, are compared to the ionic dc conductivity and relaxation times determined by broadband dielectric spectroscopy. For glyceline and ethaline, we find essentially identical temperature dependences for all dynamic quantities. These findings point to a close coupling of the ionic and molecular translational and reorientational motions in these systems. However, for reline, the ionic charge transport appears decoupled from the structural and reorientational dynamics, following a fractional Walden rule. In particular, at low temperatures, the ionic conductivity in this DES is enhanced by about one decade compared to expectations based on the temperature dependence of the viscosity. The results for all three DESs can be understood without invoking a revolving-door mechanism previously considered as a possible charge-transport mechanism in DESs.

Effect of TiO2 Nano-Filler on Electrical Properties of Na+ Ion Conducting PEO/PVDF Based Blended Polymer Electrolyte

Nanocomposite polymer electrolyte (NCPE) films based on a blend of two polymers poly (ethylene oxide) (PEO) and poly (vinylidene fluoride) (PVDF) complexed with sodium perchlorate (NaClO4) salt and Nano-filler titanium dioxide (TiO2) (i.e., (80 wt% PEO/20 wt% PVDF) + 7.5 wt% NaClO4 + x wt% TiO2 where x = 3, 6, 9, 12, 15, and 18) were prepared and characterized as potential candidates for battery applications. Electrochemical impedance spectroscopy (EIS) has been employed between the frequencies 10 Hz and 4 MHz to investigate electrical, dielectric and electric modulus properties of the prepared NCPE films. Effect of TiO2 Nano-filler concentration on the structural, ionic conductivity, and dielectric relaxation has been studied. The AC conductivity of the NCPE films at high frequencies obeys Jonscher’s power law. The values of DC ionic conductivity calculated by fitting the AC conductivity spectra to the best fit of Joncher’s power law are consistent with the values of DC ionic conductivity calculated from the bulk resistance (Rb) of the NCPE films. The ionic conductivity that depends on temperature follows the Arrhenius rule between the temperatures 298 and 328 K. The maximum ionic conductivity at ambient temperature 8.75 × 10–5 S/cm was obtained for (80 wt% PEO/20 wt% PVDF) + 7.5wt% NaClO4 + 15 wt% TiO2 NCPE film and it is attributed to the decrease in crystallinity. Using Wagner’s polarization technique ionic transport numbers of various NCPE films were measured.

The Study of Plasticized Sodium Ion Conducting Polymer Blend Electrolyte Membranes Based on Chitosan/Dextran Biopolymers: Ion Transport, Structural, Morphological and Potential Stability.

The polymer electrolyte system of chitosan/dextran-NaTf with various glycerol concentrations is prepared in this study. The electrical impedance spectroscopy (EIS) study shows that the addition of glycerol increases the ionic conductivity of the electrolyte at room temperature. The highest conducting plasticized electrolyte shows the maximum DC ionic conductivity of 6.10 × 10−5 S/cm. Field emission scanning electron microscopy (FESEM) is used to investigate the effect of plasticizer on film morphology. The interaction between the electrolyte components is confirmed from the existence of the O–H, C–H, carboxamide, and amine groups. The XRD study is used to determine the degree of crystallinity. The transport parameters of number density (n), ionic mobility (µ), and diffusion coefficient (D) of ions are determined using the percentage of free ions, due to the asymmetric vibration (υas(SO3)) and symmetric vibration (υs(SO3)) bands. The dielectric property and relaxation time are proved the non-Debye behavior of the electrolyte system. This behavior model is further verified by the existence of the incomplete semicircle arc from the Argand plot. Transference numbers of ion (tion) and electron (te) for the highest conducting plasticized electrolyte are identified to be 0.988 and 0.012, respectively, confirming that the ions are the dominant charge carriers. The tion value are used to further examine the contribution of ions in the values of the diffusion coefficient and mobility of ions. Linear sweep voltammetry (LSV) shows the potential window for the electrolyte is 2.55 V, indicating it to be a promising electrolyte for application in electrochemical energy storage devices.

The curious case of ion migration in solid-state and liquid electrolyte-based perovskite devices: unveiling the role of charge accumulation and extraction at the interfaces.

Electrochemical impedance spectroscopy (EIS) has been extensively used for the detailed investigation and understanding of the plethora of physical properties of variegated electrochemical and solid-state systems. Over the past few years, EIS has revealed many significant findings in hybrid halide perovskite (HHP)-based optoelectronic devices too. Photoinduced ion-migration, negative capacitance, anomalous mid-frequency capacitance, hysteresis, and instability to heat, light and moisture in HHP-based devices are among the few issues addressed by the IS technique. However, performing EIS in perovskite devices presents new challenges related to multilayer solid-state device geometry and complicated material properties. The ions in the perovskite behave in a specified manner, which is dictated by the energy-levels of the transport layer. Electronic-ionic coupling is one of the major challenges to understand ion transport kinetics in solid-state devices. In this work, we have performed impedance measurements in both solid-state (S-S) and liquid-electrolyte (L-E) device geometry to unfold the effect of charge transport layers on the ac ionic conductivity in perovskite materials. We have modelled the impedance spectra using the electrical equivalent circuit (EEC) and compared the behaviour of ions in different controlling environments. It was concluded that the AC as well as dc ionic conductivity and the accumulation of ions in the perovskite material are highly influenced by the nature of the interface in different device geometry. Charge accumulation in the S-S device gives rise to large polarisation, thereby negative capacitance or any inductive loop can be observed in the Nyquist plot while in the L-E device the presence of an electric double layer at the perovskite/electrolyte interface reduces the surface polarisation effect. Ionic conductivity is hopping limited in the low field regime and diffusion limited in the high field regime in the S-S device. Moreover, the perovskite/electrolyte based devices are promising candidates for electrolyte gated field-effect transistors, perovskite-based supercapacitors and electrochemical cells for water splitting or CO2 reduction.

Synthesis of Porous Proton Ion Conducting Solid Polymer Blend Electrolytes Based on PVA: CS Polymers: Structural, Morphological and Electrochemical Properties.

In this study, porous cationic hydrogen (H+) conducting polymer blend electrolytes with an amorphous structure were prepared using a casting technique. Poly(vinyl alcohol) (PVA), chitosan (CS), and NH4SCN were used as raw materials. The peak broadening and drop in intensity of the X-ray diffraction (XRD) pattern of the electrolyte systems established the growth of the amorphous phase. The porous structure is associated with the amorphous nature, which was visualized through the field-emission scanning electron microscope (FESEM) images. The enhancement of DC ionic conductivity with increasing salt content was observed up to 40 wt.% of the added salt. The dielectric and electric modulus results were helpful in understanding the ionic conductivity behavior. The transfer number measurement (TNM) technique was used to determine the ion (tion) and electron (telec) transference numbers. The high electrochemical stability up to 2.25 V was recorded using the linear sweep voltammetry (LSV) technique.

The Study of Electrical and Electrochemical Properties of Magnesium Ion Conducting CS: PVA Based Polymer Blend Electrolytes: Role of Lattice Energy of Magnesium Salts on EDLC Performance.

Plasticized magnesium ion conducting polymer blend electrolytes based on chitosan (CS): polyvinyl alcohol (PVA) was synthesized with a casting technique. The source of ions is magnesium triflate Mg(CF3SO3)2, and glycerol was used as a plasticizer. The electrical and electrochemical characteristics were examined. The outcome from X-ray diffraction (XRD) examination illustrates that the electrolyte with highest conductivity exhibits the minimum degree of crystallinity. The study of the dielectric relaxation has shown that the peak appearance obeys the non-Debye type of relaxation process. An enhancement in conductivity of ions of the electrolyte system was achieved by insertion of glycerol. The total conductivity is essentially ascribed to ions instead of electrons. The maximum DC ionic conductivity was measured to be 1.016 × 10−5 S cm−1 when 42 wt.% of plasticizer was added. Potential stability of the highest conducting electrolyte was found to be 2.4 V. The cyclic voltammetry (CV) response shows the behavior of the capacitor is non-Faradaic where no redox peaks appear. The shape of the CV response and EDLC specific capacitance are influenced by the scan rate. The specific capacitance values were 7.41 F/g and 32.69 F/g at 100 mV/s and 10 mV/s, respectively. Finally, the electrolyte with maximum conductivity value is obtained and used as electrodes separator in the electrochemical double-layer capacitor (EDLC) applications. The role of lattice energy of magnesium salts in energy storage performance is discussed in detail.

Charge Transport and Dynamics in Imidazolium Chloroaluminate Ionic Liquids

Imidazolium based chloroaluminates were the first widely studied room-temperature ionic liquids. However, work in these systems has waned over the past 25 years in favor of ionic liquids with less reactive anions. Researchers are beginning to rediscover chloroaluminates because they possess some very advantageous properties that hold significant promise for applications such as energy storage, electrodeposition, and chemical synthesis. Chloroaluminates are not simple mixtures of a single cation with a single anion. It is more appropriate to think of these systems as binary mixtures of two ionic liquids which share the same cation. The binary nature of the chloroaluimates leads to highly tunable physical and chemical properties including liquidus range, electrochemical stability window, dc ionic conductivity, zero-shear viscosity, and static dielectric permittivity. However, the binary nature also leads to significant experimental challenges with respect to characterization of the structure and anion speciation in the chloroaluminates. The majority of work characterizing the imidazolium based chloroaluminate was conducted more than 25 years ago and focused on physical property measurements across limited compositions and/or narrow temperature/frequency ranges. The data from these early studies revealed important aspects of chloroaluminate physical properties; however, due to their limited scope they failed to make significant progress in understanding underlying structure-property relationships which are critical to realizing the full potential of chloroaluminate ionic liquids as electrolyte systems. Our current work seeks to reexamine imidazolium chloroaluminate ionic liquids leveraging the improved experimental tools and capabilities available today. In this presentation we will discuss our initial studies of imidazolium chloroaluminate ionic liquids using broadband dielectric spectroscopy, oscillatory shear rheology, and Raman spectroscopy. We will present preliminary work on the impact of changes in cation structure and ionic liquid composition on anion speciation, transport properties, and dynamics.