TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The imide anion is of formula, N(CxF2x+1SO2)-N(CyF2y+1SO2)-. It includes bis(perfluoroethylsufonyl)imide (N(C2F5SO2)2-, Beti), bis(trifluoromethylsulfonyl)imide (N(CF3SO2)2-, Im), or trifluoromethane sulfonimide, or trifluoromethylsulfonimide. The electrolyte comprises a first salt including LiN(CF3SO2)2, LiN(C2F5SO2)2, or their mixtures; and a second salt including 1-ethyl-3-methylimidazolium bis(perfluoroethylsulfonyl)imide (EMIBeti), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6), or their mixtures. The second salt is present in a liquid state at working temperatures of at most 100 degreesC. The organic cation has a Van der Waals volume of at least 100 Angstrom. It is a cation of a heterocyclic compound including N, O, and/or S as heteroatom. The cation of the heterocyclic compound includes pyridinium, pyridazinium, pyrimidinium, pyrazinium, imidazolium, pyrazolium, thiazolium, oxazolium, triazolium, or their substitutes. The imidazolium compound is 1-ethyl-3-methylimidazolium(EMI), 1,2-dimethyl-3-propylimidazolium (DMPI), and/or 1-butyl-3-methylimidazolium (BMI). The second salt further comprises an anion to be linked with the organic cation and including (N(C2F5SO2)2-, Beti), (N(CF3SO2)2-, Im), trifluoromethane sulfonimide, trifluoromethylsulfonimide, trifluoromethylsulfonate, AsF9-, ClO4-, PF6-, or BF4-. The positive active material is an elemental sulfur, Li2Sn, Li2Sn dissolved in catholytes, an organosulfur compound, or carbon-sulfur polymer (C2Sx)n. The transition metal is scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, tellurium, ruthenium, rhodium, palladium, silver, cadmium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, or mercury. The group IIIA elements include aluminum, gallium, indium, and/or thallium. The group IVA elements include silicon, germanium, tin, and/or lead. The positive electrode further comprises electrically conductive materials that facilitate the movement of electrons within the positive electrode. It further comprises a current collector and a binder to adhere the positive active material to the current collector.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The binder includes poly(vinyl acetate), poly vinyl alcohol, polyethylene oxide, polyvinyl pyrrolidone, alkylated polyethylene oxide, cross-linked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride, a copolymer of polyhexafluoro propylene and polyvinylidene fluoride, poly(ethyl acrylate), polytetrafluoro ethylene, polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, polystyrene, or their derivatives, blends, or copolymers.X and y = natural numbers;n = at least 1 or 2;x = 2.5-50. EXAMPLE - 1 M LiN(CF3SO2)2 was dissolved in a mixed solvent of dimethoxyethane/dioxolane in the volume ratio of 4:1 to obtain an electrolyte. 67.5 wt.% elemental sulfur, 11.4 wt.% ketjen black as a conductive material, and 21.1 wt.% polyethylene oxide as a binder were mixed in an acetonitrile solvent to prepare a positive active material slurry for a lithium-sulfur battery cell. The slurry was coated on a carbon-coated aluminum current collector. The slurry-coated current collector was dried in a vacuum oven at 60 degreesC for more than 12 hours to obtain the positive electrode with a current density of 2 mAh/cm2 and a size of 25x50 mm2. The positive electrode (3), the vacuum dried separator (2), and the negative electrode (4) were laminated and transferred into a pouch. The pouch was sealed and the resultant pouch-type test cell was fabricated.