TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The electrolyte satisfies a range of a relative self-extinguish time (SET) (1-SETTEM/SETC), of formula (0.67 less than 1-SETTEM/SETC less than 1). In (I), a molar ratio (%) of the amide group-containing compound to the lithium salt is 1:1-8:1. The eutectic mixture containing the amide group-containing compound and the lithium (Li) salt is of formulae ((R)m X-C(=O)-N(R1)(R2) Li+Y1- ) (a) or (b). The electrolyte comprises: a first compound capable of forming a passivation layer by being reduced upon a first charge at a higher potential vs. lithium potential(vs. Li/Li+ ) than a lowest limit of an electrochemical window of the ternary eutectic mixture; and/or a second compound for consuming an overcharged current due to a higher oxidation potential vs. lithium potential (Li/Li+ ) than a cathode potential. The anode has a coating layer partially or totally formed on their surface, where the coating layer comprises a first compound reduced at a higher potential (vs. Li/Li+ ) than the ternary eutectic mixture or their reduced product. The anode is prepared, before a first discharge: by coating the first compound on a surface of an anode active material or a prefabricated anode; or by using the first compound as an anode material.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The amide group containing compound is at least one kind of material of acetamide, N-ethyl acetamide, urea, methyl urea, caprolactam, N-methyl caprolactam, N-ethyl urethane, oxazolidinone, N-hexyl oxazolidinone, valerolactam, trifluoroacetamide, methyl carbamate, ethyl carbamate, butyl carbamate or formamide. The anion of the lithium salt is at least one kind of material of F-, Cl-, Br-, I-, NO3-, N(CN)2-, BF4-, ClO4-, PF6-, (CF3)2PF4-, (CF3)3PF3-, (CF3)4PF2-, (CF3)5PF-, (CF3)6P-, CF3SO3-, (CF3CF2SO2)N2-, (CF3SO2)2N-, (FSO2)2N-, CF3CF2(CF3)2CO-, (CF3SO2)2CH-, (SF5)3C-, (CF3SO2)3C-, CF3(CF2)7SO3-, CF3CO2-, CH3CO2-, SCN- or (CF3CF2SO2)2N-. The carbonate-based compound has a cyclic structure and/or a linear structure, and is substituted or unsubstituted for a halogen atom. The carbonate-based compound is at least one kind of material of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, butylene carbonate, methylpropyl carbonate, ethylpropyl carbonate, dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone, ethylmethyl carbonate or gammabutyrolactone.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The separator comprises a polycarbonate based polymer including at least one polar functional group, a cellulose based polymer, or a copolymer of the polymers and a heteropolymer. The electrolyte is: a liquid type electrolyte; a gel polymer type electrolyte formed by carrying out polymerization of an electrolyte precursor solution (containing the ternary eutectic mixture, and monomers capable of forming a gel polymer via polymerization); or a polymer or gel polymer impregnated with the ternary eutectic mixture. The monomer is at least one kind of material of 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 paracyanostyrene. The polymer is polymethyl methacrylate, polyvinylidene difluoride, polyvinyl chloride, polyethylene oxide or polyhydroxyethyl methacrylate. The electrolyte precursor solution further comprises: polymerization initiators or photoinitiators, and a mixing ratio in the electrolyte precursor solution on the weight basis of 0.5-0.95 : 0.05-0.5 : 0.00-0.05, when expressed in terms of (ternary eutectic mixture) x: (monomer operable for forming a gel polymer by polymerization) y : (polymerization initiator) z, with provided that x+y+z = 1.SETTEM = SET from ignition to extinguishing of a certain amount of the ternary eutectic mixture;SETC = SET from ignition to extinguishing of a certain amount of the carbonate-based compound;R1, R2, R = H, halo, 1-20C alkyl, alkylamine, alkenyl or aryl;X = H, C, Si, O, N, phosphor or S; andY1 = anion capable of forming a salt with a lithium ion.Provided that: when X is H, m=0; when X is O or S, m = 1; X is N or phosphor, m = 2; and when X is C or Si, m = 3, each R is independent from the others. In formula (b),R1, R = H, 1-20C alkyl, alkylamine, alkenyl, aryl or allyl;X = H, C, Si, O, N, phosphor or S;X = C, Si, O, N, phosphor or S, except hydrogen; andY1 = anion capable of forming a salt with a lithium ion; andn = 0-10.Provided that: when X is H, m = 0 and n = 0; when X is O or S, m = 0; when X is N or phosphor, m = 1; when X is C or Si, m=2, each R being independent from the others; and n is greater than or equal to 1. EXAMPLE - Lithium cobalt dioxide as the cathode active material, artificial graphite as a conductive material, polyvinylidene fluoride as a binder were mixed in a weight ratio of 94:3:3, and N-methylpyrrolidone was added to the obtained mixture, to prepare slurry. The slurry was applied to aluminum foil, and dried at 130 degrees C for 2 hours to give the cathode. Lithium titanium oxide (Li4/3Ti5/3O4) as the anode active material, artificial graphite and a binder were mixed in a weight ratio of 94:3:3, and then N-methylpyrrolidone was added to give slurry. The slurry was applied to copper foil, and a dried at 130 degrees C for 2 hours to give the anode. The cathode and the anode with a size of 1 cm2, and a paper separator was intervened with it. Then, an electrolyte of the ternary eutectic mixture (which was prepared by adding purified methyl carbamate (4 g) and lithium (trifluormethyl sulfonyl)amine (6 g) to a flask, and then the mixture was slowly agitated at 40 degrees C under a nitrogen atmosphere for 5 hours to obtain a binary eutectic mixture. Next, ethylene carbonate (1 g) was added to give a ternary eutectic mixture) was injected to give a secondary battery.