A rechargeable lithium battery comprising: an electrolyte comprising a non-aqueous organic solvent, a lithium salt, and an additive; a positive electrode comprising a positive electrode active material; and a negative electrode comprising a negative electrode active material, wherein the non-aqueous organic solvent is only composed of a chain carbonate, the positive electrode active material comprises a cobalt-free lithium nickel manganese-based oxide, wherein the positive electrode active material is represented by Chemical Formula 4: Chemical Formula 4 Li a Ni x Mn y M 1 z M 2 w O 2±b X c, and wherein, in Chemical Formula 4, 0.5 ≤ a < 1.8, 0 ≤ b ≤ 0.1, 0 ≤ c ≤ 0.1, 0 ≤ w < 0.1, 0.6 ≤ x < 1.0, 0 < y < 0.4, 0 < z < 0.1, w + x + y + z = 1, M 1 and M 2 are each independently one or more elements selected from among Al, Mg, Ti, Zr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Cr, Fe, and Nb, and X is one or more elements selected from among S, F, P, and Cl, and the additive comprises a compound represented by Chemical Formula 1: and wherein, in Chemical Formula 1, X 1 and X 2 are each independently O, S, or CR a R b, at least one selected from among X 1 and X 2 is O, R a, R b, and R 1 to R 4 are each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C3 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C50 aryl group, a substituted or unsubstituted C7 to C50 alkylaryl group, or a substituted or unsubstituted C6 to C50 heteroaryl group, and n is an integer of 1 or 2, wherein "substituted" refers to replacement of at least one selected from among hydrogen of a substituent or a compound by deuterium, a halogen, a hydroxyl group, an amino group, a C1 to C30 amine group, a nitro group, a C1 to C40 silyl group, a C1 to C30 alkyl group, a C1 to C10 alkylsilyl group, a C6 to C30 arylsilyl group, a C3 to C30 cycloalkyl group, a C3 to C30 heterocycloalkyl group, a C6 to C30 aryl group, a C2 to C30 heteroaryl group, a C1 to C20 alkoxy group, a C1 to C10 fluoroalkyl group, and a cyano group. an electrolyte comprising a non-aqueous organic solvent, a lithium salt, and an additive; a positive electrode comprising a positive electrode active material; and a negative electrode comprising a negative electrode active material, wherein the non-aqueous organic solvent is only composed of a chain carbonate, the positive electrode active material comprises a cobalt-free lithium nickel manganese-based oxide, wherein the positive electrode active material is represented by Chemical Formula 4: Chemical Formula 4 Li a Ni x Mn y M 1 z M 2 w O 2±b X c, and wherein, in Chemical Formula 4, 0.5 ≤ a < 1.8, 0 ≤ b ≤ 0.1, 0 ≤ c ≤ 0.1, 0 ≤ w < 0.1, 0.6 ≤ x < 1.0, 0 < y < 0.4, 0 < z < 0.1, w + x + y + z = 1, M 1 and M 2 are each independently one or more elements selected from among Al, Mg, Ti, Zr, Sr, V, B, W, Mo, Si, Ba, Ca, Ce, Cr, Fe, and Nb, and X is one or more elements selected from among S, F, P, and Cl, and the additive comprises a compound represented by Chemical Formula 1: and wherein, in Chemical Formula 1, X 1 and X 2 are each independently O, S, or CR a R b, at least one selected from among X 1 and X 2 is O, R a, R b, and R 1 to R 4 are each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C3 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C50 aryl group, a substituted or unsubstituted C7 to C50 alkylaryl group, or a substituted or unsubstituted C6 to C50 heteroaryl group, and n is an integer of 1 or 2, wherein "substituted" refers to replacement of at least one selected from among hydrogen of a substituent or a compound by deuterium, a halogen, a hydroxyl group, an amino group, a C1 to C30 amine group, a nitro group, a C1 to C40 silyl group, a C1 to C30 alkyl group, a C1 to C10 alkylsilyl group, a C6 to C30 arylsilyl group, a C3 to C30 cycloalkyl group, a C3 to C30 heterocycloalkyl group, a C6 to C30 aryl group, a C2 to C30 heteroaryl group, a C1 to C20 alkoxy group, a C1 to C10 fluoroalkyl group, and a cyano group. X 1 and X 2 are each independently O, S, or CR a R b, at least one selected from among X 1 and X 2 is O, R a, R b, and R 1 to R 4 are each independently hydrogen, a halogen, a substituted or unsubstituted C1 to C20 alkyl group, a substituted or unsubstituted C1 to C20 alkoxy group, a substituted or unsubstituted C2 to C20 alkenyl group, a substituted or unsubstituted C3 to C20 alkynyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C6 to C50 aryl group, a substituted or unsubstituted C7 to C50 alkylaryl group, or a substituted or unsubstituted C6 to C50 heteroaryl group, and n is an integer of 1 or 2, wherein "substituted" refers to replacement of at least one selected from among hydrogen of a substituent or a compound by deuterium, a halogen, a hydroxyl group, an amino group, a C1 to C30 amine group, a nitro group, a C1 to C40 silyl group, a C1 to C30 alkyl group, a C1 to C10 alkylsilyl group, a C6 to C30 arylsilyl group, a C3 to C30 cycloalkyl group, a C3 to C30 heterocycloalkyl group, a C6 to C30 aryl group, a C2 to C30 heteroaryl group, a C1 to C20 alkoxy group, a C1 to C10 fluoroalkyl group, and a cyano group.