Electrolyte and secondary battery including the same

An electrolyte, comprising one or more selected from among compounds represented by Chemical Formulas 1 to 6 below:

• wherein, in Chemical Formula 1, G is —O—, —ORa—, —N(Rb)—, —Rc—N(Rd)—Re—, —Rf(NRgRh)—, or —Ri—;
• Ra, Rc, Re, Rf, and Ri are independently a linear or branched alkylene group having 1 to 10 carbon atoms;
• Rb, Rd, Rg, and Rh are independently hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms;
• Q1 and Q2 are independently phosphorus (P), sulfur (S), or arsenic (As);
• D1, D2, D3, D4, D5, and D6 are independently oxygen (═O) or one or two unshared electron pairs;
• E1, E2, E3, or E4 is oxygen (O) or carbon (C), wherein, when D2, D3, D5, or D6 is oxygen (═O), E1, E2, E3, or E4 bonded thereto is carbon (C);
• R1, R2, R3, R4, R5, R6, R7, and R8 are independently hydrogen, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkoxycarbonyl group, or an alkoxyalkyl group;
• optionally, R3 and R4 or R7 and R8 may be bonded to each other to form a ring;
• n and k are independently integers from 0 to 5;
• m and l are independently 0 or 1;
• and at least one of n and m and at least one of k and 1 are nonzero.
• wherein, in Chemical Formula 2, A1 and A2 are independently phosphorus (P) or sulfur (S);
• D7 and D8 are independently oxygen (═O) or an unshared electron pair;
• G1 and G2 are independently —O— or —CH2—;
• R9 and R10 are independently a linear or branched alkyl group having 1 to 20 carbon atoms;
• and R11, R12, R13, and R14 are independently a bond or an alkylene group having 1 to 3 carbon atoms.
• wherein, in Chemical Formula 3, X1 and X2 are independently F, Cl, Br, or I;
• E5 and E6 are independently a substituted or unsubstituted hydrocarbon group having 1 to 3 carbon atoms, and the substitution is performed with one or more selected from the group consisting of ═O, —CX′3, and —CH2CX″3;
• X′ and X″ are independently F, Cl, Br, or I;
• and bonds between carbons comprised in E5 and E6 are single bonds or double bonds.
• wherein, in Chemical Formula 4, A is phosphorus (P), sulfur (S), or nitrogen (N);
• and R15, R16, and R17 are independently a linear or branched alkyl group having 1 to 5 carbon atoms comprising substituents, and the substituents comprise one or more selected from the group consisting of halogen elements comprising F, Cl, Br, and I and oxygen (═O).
• wherein, in Chemical Formula 5, R18 and R19 are independently an alkylene group having 1 to 5 carbon atoms;
• E7 is a bond, an alkylene group having 1 to 3 carbon atoms, a cyclic carbonyl group having 2 to 5 carbon atoms, an ether group, or an ester group;
• R20 is a substituted or unsubstituted linear or cyclic carbonate group having 2 to 5 carbon atoms, a carbonyl group, an ether group, a phosphate group, a sulfonate group, or a sulfate group, and the substitution is performed with one or more selected from the group consisting of F, Cl, Br, and I or an alkenyl group having 1 to 3 carbon atoms;
• E8 is a bond, a saturated or unsaturated alkylene group having 1 to 3 carbon atoms, or an ether group;
• and n is 0 or 1.
• wherein, in Chemical Formula 6, P and O are phosphorus and oxygen, respectively;
• A is a bond or oxygen;
• Q is oxygen or an unshared electron pair;
• R21, R22, R23, and R24 are independently hydrogen, a linear or branched alkyl group having 1 to 10 carbon atoms, an alkenyl group, an alkynyl group, an alkoxy group, an alkoxycarbonyl group, an alkoxyalkyl group, fluoroalkyl, or
• optionally, R21 or R22 is bonded to R23 or R24 to form a double bond or ring;
• n is an integer from 0 to 3;
• and * is a bond position.