Papers by Keyword: LiI

Abstract: Low ionic conductivity and easily attacked by air are among the common issues of lithium salts in lithium based solid electrolytes. Toward this end, our efforts have been focused on the development of a new lithium based electrolyte system which exhibits a good stability against atmosphere and posses high electrical conductivity. Normally, lithium carbonate (Li₂CO₃) alone shows a low electrical conductivity (2×10^-5 Scm^-1). However, the corporation of lithium iodide (LiI) has made a significant impact on the electrical conductivity of the system (4.63×10^-3 Scm^-1). The xLi₂CO₃-yLiI (x = 95-70, y = 5-30 wt.%) solid electrolyte were prepared by mechanical milling technique. The electrical and structural properties of the electrolyte systems were characterized by Electrical Impedance Spectroscopy (EIS) and Fourier Transform Infrared (FTIR) respectively. The highest electrical conductivity (4.6×10^-3 Scm^-1) of the electrolyte system was obtained from the sample containing 20 wt.% of lithium iodide (LiI). The carbonate groups play a role to provide sites for the interaction between interconnected pathways and lithium ions for the fast lithium ion migration.

Abstract: In this study, the two systems of polymethylmethacrylate (PMMA) based polymer electrolyte films have been prepared by the solution casting technique. Lithium iodide (LiI) and ethylene carbonate (EC) were used as inorganic salt and plasticizer, respectively. The highest room temperature conductivity for the plasticized system and unplasticized system is 4.42 x 10^-5 Scm^-1 and 4.37 x 10^-6 Scm^-1, respectively. The conductivity-temperature dependence studies have been performed on these films in the temperature range of 303 K to 373 K. It can be observed that the log σ versus 1000/T plots obey the Arrhenius rule and VTF rule for the plasticized film and unplasticized film, respectively [1-3]. The surface morphology of the plasticized and unplasticized films was observed by using scanning electron microscope (SEM).

Abstract: The prediction of the existence and stability of (meta)-stable phases in a chemical system is realized via a two-step process: identification of structure candidates through global exploration of the classical empirical energy landscape, followed by a local optimization of the candidates on ab-initio level employing a heuristic algorithm. From the computed energy/volume curves, one can then calculate the thermodynamically stable phase at a given pressure and the transition pressures among the phases. In order to gain insight into the kinetic stability of the structure candidates, one computes estimates of the energy and enthalpy barriers around the structures with the so-called threshold algorithm, yielding a tree graph representation of the chemical system. In this work we perform a theoretical and experimental study of the LiI energy landscape. We determine the structure candidates, construct the tree graph representation and compute the abinitio energy/volume curves for the hypothetical structures. We find that the thermodynamically preferred modifications at standard pressure should exhibit the rock salt and the wurtzite structure, respectively. In order to validate our predictions by experiments, we have employed the newly developed ´Low-Temperature - Atomic Beam Deposition` (LT-ABD) technique, which allows to disperse the components of the desired product at an atomic level and in an appropriate ratio. After depositing LiI at T = 77 K, the first crystallization occurs at T » 173 K in the wurtzite-type structure followed by a transition to the more stable rock salt-type structure at T » 273 K. At room temperature only the cubic phase remains.