Showing papers by "Gholam-Abbas Nazri published in 1998"
TL;DR: In this article, the Raman spectra, conductivity, and viscosity of the EC-based binary solvent electrolytes were measured and the salt concentration was optimized for maximum conductivity.
Abstract: Electrolyte solutions formed by the addition of lithium perchlorate to a binary solvent mixture obtained by mixing ethylene carbonate (EC) with propylene carbonate (PC), diethyl carbonate (DEC), or dimethyl carbonate (DMC) were studied. The Raman spectra, conductivity, and viscosity of the EC based binary solvent electrolytes were measured. The salt concentration was optimized for maximum conductivity. Conductivity increases with increasing lithium perchlorate concentration in the EC/PC/LiClO4 electrolyte until a maximum of 6.1 kΩ-1 cm-1 is reached at 0.82 M LiClO4 (EC/PC/LiClO4 = 8/8/1). For the optimized salt concentration, the conductivity and viscosity dependence on the percent EC content of each electrolyte was measured at 25 °C. The maximum conductivity is observed for the EC/DMC/LiClO4 electrolyte at about 60% EC. The temperature dependence of conductivity and viscosity in the −30 ° to 60 °C range was also examined. The spectroscopic evidence for specific Li+ coordination is supported by quantum ch...
177 citations
TL;DR: In this paper, the vibrational spectra of manganese oxides with various amounts of lithium were studied using X-ray diffraction and Rietveld refinement techniques.
Abstract: Lithiated spinel manganese oxides with various amounts of lithium have been prepared through solid-state reaction and electrochemical intercalation and deintercalation. Structures of the LixMn2O4 samples with 0.3≤x≤1.2 are studied using X-ray diffraction and Rietveld refinement techniques. We report vibrational spectra of lithiated manganese oxides as a function of lithium concentration. The spectra of lithiated spinel manganese oxides have been analyzed on the basis of LiO4 tetrahedra and MnO6 octahedra when Li/Mn≤0.5, and LiO4, LiO6, and MnO6 structural units when Li/Mn>0.5. Electrochemical performances of lithium manganese oxide are also studied.
34 citations