Ionic conductivity

About: Ionic conductivity is a research topic. Over the lifetime, 19412 publications have been published within this topic receiving 519167 citations.

Lithium Ionic Conductor Thio-LISICON: The Li2 S ­ GeS2 ­ P 2 S 5 System

Abstract: The new crystalline material family, lithium superionic conductor (thio-LISICON), was found in the Li 2 S-GeS 2 -P 2 S 5 system. The solid solution member x x 0.75 in Li 4-x Ge 1-x P x S 4 shows the highest conductivity of 2.2 x 10 -3 S cm -1 at 25°C of any sintered ceramic together with negligible electronic conductivity, high electrochemical stability, no reaction with lithium metal, and no phase transition up to 500°C. Its material design concepts of changing constituent ions with various ionic radii, valence, and polarizability are described.

Ionic Liquids by Proton Transfer: Vapor Pressure, Conductivity, and the Relevance of ΔpKa from Aqueous Solutions

Abstract: We describe the behavior of the conductivity, viscosity, and vapor pressure of various binary liquid systems in which proton transfer occurs between neat Bronsted acids and bases to form salts with melting points below ambient. Such liquids form an important subgroup of the ionic liquid (IL) class of reaction media and electrolytes on which so much attention is currently being focused. Such “protic ionic liquids” exhibit a wide range of thermal stabilities. We find a simple relation between the limit set by boiling, when the total vapor pressure reaches one atm, and the difference in pKa value for the acid and base determined in dilute aqueous solutions. For ΔpKa values above 10, the boiling point elevation becomes so high (>300 °C) that preemptive decomposition prevents its measurement. The completeness of proton transfer in such cases is suggested by the molten salt-like values of the Walden product, which is used to distinguish good from poor ionic liquids. For the good ionic liquids, the hydrogen bond...

Electrochemical properties of imidazolium salt electrolytes for electrochemical capacitor applications

Abstract: The specific ionic conductivity, dynamic viscosity, and electrochemical stability of several imidazolium salts are reported as neationic liquids and their solutions in several organic solvents. The temperature dependence of conductivity and viscosity are analyzed for 1‐ethyl‐3‐methylimidazolium and 1,2‐dimethyl‐3‐n‐propylimidazolium salts, and the influence of theanions bis(trifluoromethylsulfonyl)imide , bis(perfluoroethylsulfonyl)imide , hexafluoroarsenate , hexafluorophosphate , and tetrafluoroborate on these properties are discussed. These imidazolium salts make possible electrolytes with high concentration (>3 M), high room temperature conductivity (up to 60 mS/cm), and a wide window of stability . Differential scanning calorimetric results confirm a large glass phase for the ionic liquids, with substantial (>80°C) supercooling. Thermal gravimetric results indicate the imidazolium salts with and anions to be thermally more stable than the lithium salt analogs. The Vogel‐Tammann‐Fulcher interpretation accurately describes the conductivity temperature dependence. © 1999 The Electrochemical Society. All rights reserved.

Self-Assembly of Phase-Segregated Liquid Crystal Structures

Abstract: Additional functionality can be incorporated into liquid crystalline materials by using phase segregation and self-assembly. Intermolecular interactions such as hydrogen bonding and ionic interactions play key roles in the formation of these complex structures. One-, two-, and three-dimensional phase-segregated structures on various scales of length are formed by self-assembly of a variety of partially incompatible molecules. Such structures can enhance anisotropic properties such as ionic conductivity.

Mesoscopic fast ion conduction in nanometre-scale planar heterostructures

Abstract: Ion conduction is of prime importance for solid-state reactions in ionic systems, and for devices such as high-temperature batteries and fuel cells, chemical filters and sensors Ionic conductivity in solid electrolytes can be improved by dissolving appropriate impurities into the structure or by introducing interfaces that cause the redistribution of ions in the space-charge regions Heterojunctions in two-phase systems should be particularly efficient at improving ionic conduction, and a qualitatively different conductivity behaviour is expected when interface spacing is comparable to or smaller than the width of the space-charge regions in comparatively large crystals Here we report the preparation, by molecular-beam epitaxy, of defined heterolayered films composed of CaF2 and BaF2 that exhibit ionic conductivity (parallel to the interfaces) increasing proportionally with interface density--for interfacial spacing greater than 50 nanometres The results are in excellent agreement with semi-infinite space-charge calculations, assuming a redistribution of fluoride ions at the interfaces If the spacing is reduced further, the boundary zones overlap and the predicted mesoscopic size effect is observed At this point, the single layers lose their individuality and an artificial ionically conducting material with anomalous transport properties is generated Our results should lead to fundamental insight into ionic contact processes and to tailored ionic conductors of potential relevance for medium-temperature applications