TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred Components: The first compound is used in an amount of 0.01-10 parts by weight (pbw) based on 100 pbw of the electrolyte. The first compound has a reduction potential versus lithium potential (Li/Li+) of 0-2 Volts. The first compound is reduced and decomposed in advance of the eutectic mixture on the initial charge of the battery to form a solid electrolyte interface (SEI) layer. The electrolyte further comprises a second compound having a higher oxidation potential (versus Li/Li+) than the cathode potential. The second compound consumes an overcharge current. The second compound is at least one compound selected from iodine, ferrocene-based compounds, triazolium salts, tricyanobenzene, tetracyanoquinodimethane, benzene-based compounds, pyrocarbonates and cyclohexylbenzene (CHB). The anode includes an anode active material selected from metal oxides and carbonaceous materials having a reduction potential versus lithium potential (Li/Li+) of lower than 1 V. The lower limit of the electrochemical window of the eutectic mixture is 0.5-2 V; the anode has a reduction potential versus lithium potential (Li/Li+) of 0 to the lower limit of the electrochemical window of the eutectic mixture; and the first compound has a higher potential versus lithium potential (Li/Li+) than the lower limit of the electrochemical window of the eutectic mixture, and is reduced on the initial charge to form a solid electrolyte interface (SEI) layer. The electrolyte comprises a eutectic mixture formed of the amide group-containing compound and the ionizable lithium salt; and the anode is an electrode preliminarily coated with a coating layer partially or totally formed on its surface, the coating layer comprises the first compound reduced at a higher potential versus lithium potential (Li/Li+) than the eutectic mixture or its reduced product. The anode is any one electrode selected from the following: (a) an electrode coated with the first compound on a surface of the electrode active material or a surface of a preliminarily formed electrode; (b) an electrode using the first compound as a material for forming the electrode; and (c) an electrode obtained by dipping the electrode into a solution containing the first compound and by carrying out charge/discharge cycles so that a solid electrolyte interface layer comprising the first compound or its reduced product is formed on its surface.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The first compound is selected from 12-crown-4, 18-crown-6, catechol carbonate, vinylene carbonate, ethylene sulfite, methyl chloroformate, succinimide and methyl cinnamate. The eutectic mixture comprises: (a) an amide group-containing compound; and (b) an ionizable lithium salt. The eutectic mixture is represented by the amide-group containing compound of formula (R)m-X-C(O)-NR1R2 Li+(Y1)- (I), or the linear or cyclic amide-group containing compound of formula (II). The amide group-containing compound is selected from acetamide, urea, methylurea, caprolactam, valerlactam, trifluoroacetamide, methyl carbamate, formate or formamide. The anion in the lithium salt is selected from F-, Cl-, Br-, I-, (NO3)-, (N(CN)2)-, (BF4)-, (ClO4)-, (PF6)-, ((CF3)2PF4)-, ((CF3)3PF3)-, ((CF3)4PF2)-, ((CF3)5PF)-, ((CF3)6P)-, (CF3SO3)-, (CF3CF2SO3)-, ((CF3SO)2)2N)-, ((FSO2)2N)-, (CF3CF2(CF3)2CO)-, ((CF3SO2)2CH)-, (SF5)3C-, ((CF3SO2)3C)-, (CF3(CF2)7SO3)-, (CF3CO2)-, (CH3CO2)-, SCN-, or (CF3CF2SO2)2N-.R, R1 and R2=H, halo, 1-20C alkyl, alkylamine, alkenyl or aryl;X and X1=H, carbon, silicon, oxygen, nitrogen, phosphor and sulfur;Y1=anion forming a salt with lithium;Ra and R1a=H, 1-20C alkyl, alkylamine, alkenyl, aryl or allyl;m=0-3;n=0-10.Provided that:(1) when X is H, then m is 0; when X is O or S, then m is 1; when X is N or P, then m is 2; and when X is C or Si, then m is 3;(2) when X1 is H, then m and n are 0; when X1 is O or S, then m is 0; when X1 is N or P, then m is 1; and when X1 is C or Si, then m is 2; and(3) when n is greater than or equal to 1, then X1 is carbon, silicon, oxygen, nitrogen, phosphorus or sulfur, except H.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The electrolyte is a liquid type electrolyte, which is a gel polymer type electrolyte obtained by polymerizing an electrolyte precursor solution comprising: (i) a eutectic mixture; (ii) a first compound reduced at a higher potential versus lithium potential than the lowest limit of the electrochemical window of the eutectic mixture; and (iii) monomers forming a gel polymer via polymerization. The monomer is at least one vinyl monomer selected from acrylonitrile, methyl methacrylate, methyl acrylate, methacrylonitrile, methyl styrene, vinyl esters, vinyl chloride, vinylidene chloride, acrylamide, tetrafluoroethylene, vinyl acetate, methyl vinyl ketone, ethylene, styrene, para-methoxystyrene or para-cyanostyrene. The electrolyte precursor solution further comprises a polymerization initiator. The electrolyte is formed by in-situ polymerization inside a battery. The electrolyte is obtained by impregnating a polymer or gel polymer with (i) the eutectic mixture; and (ii) the first compound reduced at a higher potential versus lithium potential than the lowest limit of the electrochemical window of the eutectic mixture. The polymer is selected from polymethyl methacrylate, polyvinylidene difluoride, polyvinyl chloride, polyethylene oxide and polyhydroxyethyl methacrylate. EXAMPLE - A secondary battery was prepared. A mixture of purified methyl carbamate (5 g) and lithium salt Li(CF3SO2)2N (6 g) was agitated gradually at room temperature under nitrogen atmosphere for 12 hours to obtain a eutectic mixture (11 g). The eutectic mixture was dried to a water content of less than or equal to 20 ppm under a vacuum. The eutectic mixture was evaluated for and showed physical properties as follows: viscosity (23.5 centipoise (cP)); electric conductivity (1.43 mS/cm); and electrochemical window (0.5-5.5 volts). To the eutectic mixture, vinylene carbonate (2 V versus Li potential) (5 wt.%) was added to obtain an electrolyte. Graphite as an anode active material, artificial graphite and a binder were mixed in a weight ratio of 94:3:3, and N-methylpyrrolidone was added to the resultant mixture to provide slurry. The slurry was applied to a copper foil, and then dried at 130degrees C for 2 hours to provide an anode. LiCoO2 as a cathode active material, artificial graphite as a conductive agent and polyvinylidene fluoride as a binder were mixed in a weight ratio of 94:3:3, and N-methylpyrrolidone was added to the resultant mixture to provide slurry. The slurry was applied to aluminum foil, and dried to provide a cathode. The cathode and the anode obtained were provided, each in a size of 1 cm2, and a separator was inserted between both electrodes, and the electrolyte was injected into the separator to obtain a secondary battery. The battery was subjected to a charge/discharge test, and it was observed that the battery showed excellent energy density and was safe against overcharge, overdischarge, and generation of a short and thermal impact.