Herein, we report the characteristics of electrolytes using various ether-solvents with molecular composition CH3O[CH2CH2O]nCH3, differing by chain length, and LiCF3SO3 as the lithium salt. The electrolytes, considered as suitable media for lithium-sulfur batteries, are characterized in terms of thermal properties (TGA, DSC), lithium ion conductivity, lithium interface stability, cyclic voltammetry, self-diffusion properties of the various components, and lithium transference number measured by NMR. Furthermore, the electrolytes are characterized in lithium cells using a sulfur-carbon composite cathode by galvanostatic charge-discharge tests. The results clearly evidence the influence of the solvent chain length on the species mobility within the electrolytes that directly affects the behavior in lithium sulfur cell. The results may effectively contribute to the progress of an efficient, high-energy lithium-sulfur battery.

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We propose in this work a polyethylene glycol dimethyl ether (MW 500) dissolving lithium trifluoromethansulfonate (LiCF3SO3) salt as suitable electrolyte media for a safe and efficient use of the lithium metal anode in battery. Voltammetry and galvanostatic tests reveal significant enhancement of the electrolyte characteristics, in terms of cycling life and chemical stability, by the addition of lithium nitrate (LiNO3) to the solution. Furthermore, PFG NMR measurements suggest the applicability of the electrolyte in battery in terms of ionic conductivity, lithium transference number, ionic-association degree and self-diffusion coefficient. Accordingly, the electrolyte is employed in a lithium battery using lithium iron phosphate as the selected cathode. The battery delivers a stable capacity of 150mAhg-1 and flat working voltage of 3.5 V, thus\ud leading to a theoretical energy density referred to the cathode of 520Wh kg-1. This battery is considered a suitable energy storage system for advanced applications requiring both high safety and high energy density

Lithium sulfur and lithium oxygen batteries are a step forward for sustainable energy storage.

We propose lithium metal cells employing LiCF3SO3-tetraethylene glycol dimethy ether (TEGDME)\ud electrolyte solution with LiFePO4 and LiMn0.5Fe0.5PO4 cathodes. The electrolyte is selected due to its nonflammability, herein demonstrated, and considered as a key requirement for application cells employing\ud high energy lithium metal anode. The selected olivine cathodes, i.e., stable materials prepared by solvothermal\ud pathway, have regular submicrometrical morphology suitable for cell operation and homogeneous\ud composition, as confirmed by electron microscopy and energy dispersive X-ray spectroscopy.\ud The electrochemical tests reveal promising cycling performances in terms of delivered capacity, stability\ud and rate capability. The Li/LiCF3SO3-TEGDME/LiFePO4 cell operates at 3.5 V with capacity ranging from\ud 150 mAh g-1 at C/10 to 110 mAh g-1 at 2C, while the Li/LiCF3SO3-TEGDME/LiFe0.5Mn0.5PO4 cell performs\ud following two plateaus at 4.1 V and 3.5 V with capacity ranging from 160 mAh g-1 at C/10 to\ud 75 mAh g-1 at 2C. Hence, the results demonstrate the suitability of TEGDME-based electrolytes in\ud combination with LiFePO4 and LiFe0.5Mn0.5PO4 cathodes for high performances lithium battery