TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The cathode active material comprises amorphous carbon. The amorphous carbon is hard carbon and/or soft carbon. The lithium metal phosphate is lithium iron phosphate having olivine crystalline structure of formula: Li1+aFe1-xM'x(PO4-b)Xb, where M' is aluminum, magnesium, nickel, cobalt, manganese, titanium, gallium, copper, vanadium, niobium, indium, zinc or yttrium, and x is 0-0.5. The lithium iron phosphate having olivine crystalline structure is coated with conductive carbon. The concentration of lithium salt in the electrolyte is 0.5-3 M. The lithium salt is chosen from lithium chloride, lithium bromide, lithium iodide, lithium perchlorate, lithium tetrafluoroborate, lithium boron chloride (LiB10Cl10), lithium hexafluorophosphate, lithium trifluoromethanesulfonate, lithium trifluorroacetate, lithium hexaflouroarsenate, lithium hexafluroantimonate, lithium aluminum chloride, lithium bis(trifluoromethylsulfonyl)imide, lithium trifluoromethanesulfonate, lithium methanesulfonate, lithium tetraphenylborate, and imide. Preferred Property: The binding energy of lithium ion and sulfanyl-based solvent is 0.1-4 eV.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The electrolyte further comprises carbonate-type solvent and/or ether-based solvent. The mix ratio of sulfanyl-based solvent and carbonate-type solvent is 20:80-80:20 based on total volume of electrolyte. The mix ratio of sulfanyl-based solvent and ether-type solvent is 5:95-50:50 based on total volume of electrolyte. The content of sulfanyl-based solvent, carbonate-type solvent and ether-based solvent is 10-80 vol.%, 10-80 vol.% and 1-10 vol.%, respectively with respect to total volume of electrolyte. The sulfanyl-based solvent comprises bis(methylsulfanyl)methane of formula (I), 1,2-bis(methylsulfanyl)ethane of formula (II), 1,2-bis(ethylsulfanyl)ethane of formula (III), 1,5-bis(methylsulfanyl)petane of formula (IV), and/or tetrahydro-thiophene of formula (V). The ether-based solvent is chosen from tetrahydrofuran, 2-methyltetrahydrofuran, dimethoxyethane and dibutyl ether. The linear carbonate is chosen from dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate and ethyl propyl carbonate.    TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The cyclic carbonate is chosen from ethylene carbonate, polypropylene carbonate, 1,2-butylene carbonate, 2,3-butylene carbonate, 1,2-pentylene carbonate and 2,3-pentylene carbonate. The ratio of cyclic carbonate and linear carbonate is 1:4-4:1 with respect to total content of carbonate-type solvent.